阅读说明：本技术 车辆用稳定系统 (Stabilizing system for vehicle ) 是由 田畑雅朗 村田和行 山本将司 于 2021-04-26 设计创作，主要内容包括：在本发明的前轮侧稳定装置、后轮侧稳定装置的每一个中,由1个以上的缸体支承稳定杆,设置将各缸体的两个液室相连的连通路,并且在该连通路配设可选择地实现两个液室相互连通的液室间连通状态和相互截断的液室间截断状态的开闭阀,在液室间截断状态下,发挥车身侧倾抑制效果,在液室间连通状态下,将车身侧倾抑制效果无效化。而且,设置使各稳定装置的两个状态的变更联动的联动机构。(In each of the front wheel side stabilizer and the rear wheel side stabilizer of the present invention, the stabilizer bar is supported by 1 or more cylinders, a communication passage is provided for connecting the two liquid chambers of each cylinder, and an on-off valve is provided in the communication passage for selectively achieving an inter-liquid-chamber communication state in which the two liquid chambers are communicated with each other and an inter-liquid-chamber cutoff state in which the two liquid chambers are blocked from each other. Further, a linkage mechanism for linking the change of the two states of each stabilizer is provided.)

1. A vehicle stabilization system comprising a 1 st stabilization device provided on one of a front wheel and a rear wheel and a 2 nd stabilization device provided on the other of the front wheel and the rear wheel,

the 1 st and 2 nd stabilizing devices are respectively configured,

comprising: a stabilizer bar extending to the left and right; 1 or more cylinders each including a housing and a piston dividing the housing into two liquid chambers, and arranged between the stabilizer bar and a wheel or a vehicle body in a telescopic manner; a communication passage that connects the two liquid chambers of the 1 or more cylinders; and an on-off valve disposed in the communication passage and selectively achieving an inter-liquid-chamber communication state in which the two liquid chambers are communicated with each other and an inter-liquid-chamber cutoff state in which the two liquid chambers are cutoff from each other, wherein the 1 st stabilizing device and the 2 nd stabilizing device exhibit a vehicle-body-roll suppressing effect in the inter-liquid-chamber cutoff state and negate the vehicle-body-roll suppressing effect in the inter-liquid-chamber communication state,

the vehicle stabilization system includes a link mechanism that, when a liquid-chamber cutoff state is achieved in one of the 1 st and 2 nd stabilizing devices, causes a driven stabilizing device that is the other of the 1 st and 2 nd stabilizing devices to also achieve a liquid-chamber cutoff state.

2. The stabilizing system for a vehicle according to claim 1,

the opening and closing valve of the active stabilization device is an electromagnetic valve that can be electrically controlled,

the vehicle stabilization system includes an introduction path that introduces one of the hydraulic pressures in the two liquid chambers of each of the 1 or more cylinders of the active stabilization device into the driven stabilization device, and the on-off valve of the driven stabilization device is a non-electromagnetic valve that operates using the hydraulic pressure introduced from the introduction path as a pilot pressure, thereby configuring the linkage mechanism.

3. The stabilizing system for a vehicle according to claim 2,

the interlocking mechanism includes a switching valve that is a non-electromagnetic valve for introducing the higher one of the hydraulic pressures in the two liquid chambers of the 1 or more cylinders of the active stabilizer to the driven stabilizer.

4. The stabilizing system for a vehicle according to claim 2 or 3,

the on-off valve of the active stabilizer is a normally closed electromagnetic valve that is opened by being excited.

5. The stabilizing system for a vehicle according to any one of claims 2 to 4,

for the 1 or more cylinders of any one of the 1 st and 2 nd stabilizing devices,

all of which have a piston rod, a base end portion of which is coupled to the piston and a tip end portion of which passes through one of the two liquid chambers and protrudes from the housing,

the housing is coupled to one of the stabilizer bar and the wheel or the vehicle body, and the distal end portion of the piston rod is coupled to the other of the stabilizer bar and the wheel or the vehicle body.

6. The stabilizing system for a vehicle according to claim 5,

and an accumulator connected to both the communication path of the 1 st stabilizer and the communication path of the 2 nd stabilizer so that all of the 1 or more cylinders of any one of the 1 st stabilizer and the 2 nd stabilizer can expand and contract in a state where they communicate with each other between liquid chambers.

7. The stabilizing system for a vehicle according to claim 6,

at least one of the communication passage of the 1 st stabilizer and the communication passage of the 2 nd stabilizer is connected to the accumulator via the introduction passage.

8. The stabilizing system for a vehicle according to claim 6 or 7,

the vehicle stabilization system includes a shut-off valve for shutting off the accumulator when both the 1 st and 2 nd stabilization devices are in the inter-liquid-chamber cutoff state.

9. The stabilizing system for a vehicle according to claim 8,

the shut-off valve is an electromagnetic valve which can be electrically controlled.

10. The stabilizing system for a vehicle according to claim 9,

the shut valve is a normally open electromagnetic valve that is excited to close.

11. The stabilizing system for a vehicle according to any one of claims 1 to 10,

at least one of the 1 st stabilizer and the 2 nd stabilizer is a twin cylinder type stabilizer,

in the double-cylinder type stabilizer device,

both ends of the stabilizer bar are connected to a pair of wheel holding portions that hold the left and right wheels and move up and down with the wheels held by the wheel holding portions relative to the vehicle body,

the 1 or more cylinders include a pair of cylinders each configured to: the stabilizer bar is arranged between a pair of supported portions provided on left and right portions of the stabilizer bar, respectively, to be supported by a vehicle body, and is configured to expand and contract according to a rebounding operation and a bouncing operation of a corresponding one of left and right wheels with respect to the vehicle body, wherein a first liquid chamber 1 as one of the two liquid chambers has an increased volume during the rebounding operation of the corresponding wheel, and has a decreased volume during the bouncing operation, and a second liquid chamber 2 as the other of the two liquid chambers has a decreased volume during the rebounding operation of the corresponding wheel, and has an increased volume during the bouncing operation,

the communication path includes a 1 st communication path that communicates the 1 st liquid chamber of one of the pair of cylinders with the 2 nd liquid chamber of the other, a 2 nd communication path that communicates the 2 nd liquid chamber of the one of the pair of cylinders with the 1 st liquid chamber of the other, and an inter-path communication path that communicates the 1 st communication path with the 2 nd communication path with each other, and the on-off valve is disposed in the inter-path communication path.

12. The stabilizing system for a vehicle according to claim 11,

the two-cylinder stabilizer includes a bracket for holding the stabilizer bar to a vehicle body at a held portion provided at a center portion in a vehicle width direction and allowing rotation of the stabilizer bar in accordance with a bouncing operation of one of left and right wheels and a rebounding operation of the other.

13. The stabilizing system for a vehicle according to any one of claims 1 to 12,

at least one of the 1 st stabilizer and the 2 nd stabilizer is a single-cylinder body-type stabilizer,

in the single-cylinder type stabilizing device,

both ends of the stabilizer bar and a pair of wheel holding portions that hold the left and right wheels and that move up and down relative to the vehicle body together with the wheels held by the wheel holding portions are connected to one side of the vehicle body and supported by the other side of the vehicle body and the pair of wheel holding portions,

the 1 or more cylinders include one cylinder configured to: and a pair of liquid chambers which are disposed between the pair of wheel holding portions and one of the vehicle body and the both ends of the stabilizer bar, and which expand and contract in accordance with a rebound operation of one of the left and right wheels and a rebound operation of the other of the left and right wheels, wherein one of the two liquid chambers increases in volume when the cylinder is extended, decreases in volume when the cylinder is retracted, and decreases in volume when the cylinder is extended, and increases in volume when the cylinder is retracted.

14. The stabilizing system for a vehicle according to claim 13,

the single-cylinder type stabilizer is provided for right and left wheels suspended by a rigid axle type suspension.

15. The stabilizing system for a vehicle according to claim 14,

with respect to the single-cylinder body type stabilizer,

the stabilizer bar is supported by an axle housing having both ends serving as the pair of wheel holding portions, and the both ends of the stabilizer bar are coupled to left and right portions of the vehicle body, respectively.

16. The stabilizing system for a vehicle according to any one of claims 1 to 15,

the structure is as follows: when the 1 st and 2 nd stabilizing devices both achieve the inter-liquid-chamber cutoff state, the roll rigidity on the front-wheel side is higher than the roll rigidity on the rear-wheel side.

17. The stabilizing system for a vehicle according to any one of claims 1 to 16,

the vehicle stabilization system is provided with a controller for controlling the vehicle stabilization system.

18. The stabilizing system for a vehicle according to claim 17,

the controller is configured to:

the active stabilizer device is configured to establish a state of communication between the liquid chambers in a situation where a vehicle equipped with the vehicle stabilization system is traveling outdoors or a situation where it is scheduled to travel outdoors.

19. The stabilizing system for a vehicle according to claim 17 or 18,

the controller is configured to:

the active stabilizer device is configured to achieve a state in which the liquid chambers are blocked, on the basis of turning of a vehicle on which the vehicle stabilizer system is mounted.

Technical Field

The present invention relates to a stabilization system mounted on a vehicle.

Background

The stabilizer system is mounted on the vehicle to suppress roll of the vehicle, and the stabilizer bar is configured as a main structural element. In recent years, as development of a stabilizer system has progressed, for example, as described in japanese patent laid-open No. 2009-23650 described below, it has been studied to optimize control relating to roll of a vehicle by controlling a vehicle body roll restraining effect obtained by a stabilizer bar using a hydraulic cylinder.

The above-described stabilization system described in japanese patent application laid-open No. 2009-23650, that is, the stabilization system including the stabilization device to which the hydraulic cylinder is applied, has a lot of room for improvement, and the practicability of the stabilization system can be improved by applying some improvements.

Disclosure of Invention

The present invention has been made in view of such circumstances, and an object thereof is to provide a highly practical vehicle stabilization system.

In order to solve the above problem, a vehicle stabilizer system according to the present invention (hereinafter, sometimes abbreviated as "stabilizer system") includes a first stabilizer device 1 provided on one of a front wheel and a rear wheel, and a second stabilizer device 2 provided on the other of the front wheel and the rear wheel, wherein each of the first stabilizer device and the second stabilizer device is configured to include: (a) a stabilizer bar extending to the left and right; (b)1 or more cylinders each including a housing and a piston defining two liquid chambers in the housing, and arranged between the stabilizer bar and a wheel or a vehicle body in a telescopic manner; (c) a communication passage that connects the two liquid chambers of the 1 or more cylinders; and (d) an on-off valve disposed in the communication passage and selectively operable to establish a liquid chamber communication state in which the two liquid chambers are communicated with each other and a liquid chamber cutoff state in which the two liquid chambers are cutoff, wherein the 1 st stabilizer and the 2 nd stabilizer exhibit a vehicle body roll suppression effect in the liquid chamber cutoff state and negate the vehicle body roll suppression effect in the liquid chamber communication state, and wherein the vehicle stabilization system includes a linkage mechanism that causes the driven stabilizer that is one of the 1 st stabilizer and the 2 nd stabilizer to also achieve the liquid chamber cutoff state when the active stabilizer that is the other of the 1 st stabilizer and the 2 nd stabilizer achieves the liquid chamber cutoff state.

According to the present invention, since the two stabilizer devices disposed respectively on the front wheel and the rear wheel are interlocked by the interlocking mechanism, one of the two stabilizer devices can exhibit the vehicle body roll suppression effect, and the other can also exhibit the vehicle body roll suppression effect, thereby constructing a simple and convenient stabilizer system. Therefore, the stabilization system of the present invention is practical.

In the stabilization system of the present invention, for example, the following may be provided: the interlocking mechanism is configured such that the on-off valve of the active stabilizer is an electromagnetic valve that can be electrically controlled, the interlocking mechanism includes an introduction path that introduces one of the hydraulic pressures in the two liquid chambers of each of the 1 or more cylinders of the active stabilizer into the driven stabilizer, and the on-off valve of the driven stabilizer is a non-electromagnetic valve that operates using the hydraulic pressure introduced from the introduction path as a pilot pressure. With this configuration, the electromagnetic on-off valve of the active stabilizer is electrically controlled, whereby the front and rear stabilizers can be linked to each other with respect to the presence or absence of the vehicle body roll suppression effect. In addition, in the case where the on-off valve is in a state in which the liquid chambers communicate with each other, a relatively large flow rate of the working liquid must be passed through the on-off valve. Since a relatively large-sized electromagnetic valve is relatively expensive, the above-described opening/closing valve of the driven stabilizer can be a non-electromagnetic valve, and thus the stabilizer system can be constructed relatively inexpensively.

The following may be configured: the interlocking mechanism is configured to include a switching valve that is a non-electromagnetic valve for introducing, when the pilot pressure is introduced to the driven stabilizer, the higher one of the hydraulic pressures in the two liquid chambers of the 1 or more cylinders of the active stabilizer to the driven stabilizer. With this configuration, the pilot pressure suitable for the linkage of the two stabilizers can be introduced from the driving stabilizer to the driven stabilizer with a relatively simple configuration and efficiently.

The following may be configured: as the on-off valve of the active stabilizer, a normally closed electromagnetic valve that is opened by being excited is used. If a normally closed electromagnetic valve is used, the vehicle body roll suppression effect of the active stabilizer device is maintained even when an electrical failure occurs in the stabilizer system.

The 1 st and 2 nd stabilizing devices may be configured such that 1 or more cylinders thereof respectively: the stabilizer includes a piston rod, a base end portion of which is coupled to the piston, and a tip end portion of which extends out from a housing through one of the two liquid chambers, the housing is coupled to one of the stabilizer and the wheel or the vehicle body, and the tip end portion of which is coupled to the other of the stabilizer and the wheel or the vehicle body. In brief, as 1 or more cylinders, a general cylinder, that is, a cylinder in which a piston rod extends only from one side of a housing (hereinafter, referred to as a "rod-one-side extending cylinder" in some cases) can be used. The single-sided extension of the rod out of the cylinder is constructionally simple and inexpensive. On the other hand, a cylinder different from the rod one-side extending cylinder may be used, and in detail, a cylinder in which a piston rod extends from both sides of a housing (hereinafter, sometimes referred to as a "rod both-side extending cylinder"), in other words, a cylinder in which a piston rod passes through both liquid chambers may be used. The piston is more expensive than the rod-one-side extension cylinder due to the complexity of the structure, but the pressure receiving area on which the pressure of the working fluid in one of the two fluid chambers acts can be made equal to the pressure receiving area on which the pressure of the working fluid in the other of the two fluid chambers acts.

In the case of the rod-one-side extension cylinder, there is a difference between the inflow and outflow of the working fluid to one of the two liquid chambers and the inflow and outflow of the working fluid to the other of the two liquid chambers, which are caused by the expansion and contraction of the cylinder. In view of this, the following configuration may be adopted: in order to expand and contract in a state where the liquid chambers communicate with each other with respect to one or more cylinders of the 1 st and 2 nd stabilizing devices, an accumulator is provided which is connected to both of the communication path of the 1 st and 2 nd stabilizing devices. According to the form in which this accumulator is provided, the accumulator is shared by the two stabilizer devices, and therefore simplification of the stabilizer system can be achieved. In this aspect, at least one of the communication passage of the 1 st stabilizer and the communication passage of the 2 nd stabilizer may be connected to the accumulator through the introduction passage.

On the other hand, when the accumulator is provided, it is preferable to interrupt the communication path from the accumulator in order to prohibit extension and contraction of the piston when the inter-liquid chamber blocking state is realized. In view of this, in the embodiment in which the accumulator is provided, it is preferable to provide a shut valve for shutting off the accumulator when both the 1 st and 2 nd stabilizing devices are in the inter-liquid-chamber blocked state. Further, the following may be configured: the shut valve is an electrically controllable electromagnetic valve, more specifically, a normally open electromagnetic valve that is excited to close. If the shut-off valve is an electromagnetic valve, it can be electrically operated simultaneously with the on-off valve of the active stabilizer. In addition, in the case of a normally open electromagnetic valve, even if an electrical failure occurs, expansion and contraction of the cylinder in the case where the stabilizer is in a state of communication between the liquid chambers are permitted.

As an example of the applicable stabilizer, for example, a twin cylinder type stabilizer may be used for at least one of the 1 st stabilizer and the 2 nd stabilizer. In the two-cylinder type stabilizer, both ends of the stabilizer bar are connected to a pair of wheel holding portions, respectively, and the pair of wheel holding portions hold the left and right wheels and move up and down with the wheels held by the wheel holding portions with respect to the vehicle body, and the stabilizer bar includes a pair of cylinders as the 1 or more cylinders. The pair of cylinders are respectively configured as follows: the stabilizer bar is disposed between a pair of supported portions provided on left and right portions of the stabilizer bar, and the stabilizer bar is extended and contracted in accordance with a rebound operation and a bounce operation of a corresponding one of left and right wheels with respect to a vehicle body, wherein a first liquid chamber 1 as one of two liquid chambers increases in volume during the rebound operation of the corresponding wheel, decreases in volume during the bounce operation, and a second liquid chamber 2 as the other of the two liquid chambers decreases in volume during the rebound operation of the corresponding wheel, and increases in volume during the bounce operation. The communication path includes a 1 st communication path for communicating the 1 st liquid chamber and the 2 nd liquid chamber of one of the pair of cylinders, a 2 nd communication path for communicating the 2 nd liquid chamber and the 1 st liquid chamber of the other of the pair of cylinders, and an inter-path communication path for communicating the 1 st communication path and the 2 nd communication path with each other, and the on-off valve is disposed in the inter-path communication path.

The 1 st communication passage and the 2 nd communication passage in the two-cylinder stabilizer of the above-described embodiment may be regarded as, for example, cross pipes, and the two-cylinder stabilizer of the above-described embodiment may be regarded as two hydraulic systems each including one of the 1 st communication passage and the 2 nd communication passage and two liquid chambers of a cylinder connected thereto through the one. In the above-described stabilizer, the inter-liquid-chamber communication state and the inter-liquid-chamber blocked state are selectively achieved by controlling the operation of the on-off valve provided in the inter-passage communication path.

When the liquid chamber cutoff state is achieved, the two hydraulic systems are in an independent state, and thereby the extension and contraction of each of the pair of cylinders is restricted, and the positional variation of each of the pair of supported portions of the stabilizer bar, specifically, the positional variation with respect to the vehicle body is prohibited. As a result, when the vehicle body is tilted, the stabilizer bar is twisted as in a normal stabilizer, and the reaction force of the twist acts between the left and right wheels and the vehicle body as a roll restraining force, thereby effectively restraining the roll of the vehicle body.

On the other hand, when the inter-liquid-chamber communication state is achieved, relatively free outflow and inflow of the working fluid to and from the two liquid chambers of the pair of cylinders, that is, to and from each of the 4 liquid chambers are allowed, and thus relatively free positional variation of the pair of supported portions of the stabilizer bar is allowed in accordance with the vertical movement of the left and right wheels. As a result, the generation of the roll-restraining force is restricted, and the road surface input to the left and right wheels can be effectively absorbed when traveling in the open air, that is, when traveling on a road surface (ground surface) having irregularities, a poor road surface, or the like. In other words, it is possible to suppress the relative motion between one of the left and right wheels and the vehicle body due to the road surface input to the other of the left and right wheels, and thereby to maintain the riding comfort of the vehicle during the field traveling and the like in a satisfactory manner.

In the two-cylinder type stabilizer according to the above aspect, since the 1 st communication passage and the 2 nd communication passage extend together over a relatively long distance in the vehicle width direction, the inter-passage communication passage communicates with each other at a portion where the 1 st communication passage and the 2 nd communication passage are close to each other, and thus the inter-passage communication passage can be a relatively short communication passage.

The following may be configured: in the above-described two-cylinder type stabilizer, a bracket for holding the stabilizer bar is provided at a held portion provided at a central portion in the vehicle width direction. The bracket allows the stabilizer bar to rotate in accordance with the bouncing operation of one of the left and right wheels and the rebounding operation of the other, and holds the stabilizer bar to the vehicle body. In the above-described two-cylinder stabilizer device, in the state where the liquid chambers are communicated with each other, for example, the stabilizer bar is simply allowed to rotate such that the pair of supported portions move in the vertical direction by the same distance in the opposite directions to each other. In particular, when the rod is extended to the cylinder on one side, the pressure receiving area of the piston on which the pressure of the working fluid in the 1 st fluid chamber acts is different from the pressure receiving area on which the pressure of the working fluid in the 2 nd fluid chamber acts, and therefore, it is considered that both the pair of supported portions move in the same direction in the vertical direction, that is, the supported portions move in the same direction in a state where the fluid chambers communicate with each other. By providing the bracket, the movement of the supported portion in the same direction can be suppressed. For convenience, for example, the following structure may be adopted: the bracket is configured to include a held portion bushing, and the above-described rotation of the stabilizer bar is permitted by the elasticity of the held portion bushing.

As another example of the applicable stabilizer, for example, a single-cylinder stabilizer may be applied to at least one of the 1 st stabilizer and the 2 nd stabilizer. In this single-cylinder type stabilizer, both ends of the stabilizer bar are connected to one of a pair of wheel holding portions that hold the left and right wheels, respectively, and that move up and down relative to the vehicle body together with the wheels held by the wheel holding portions, respectively, and the vehicle body, and the stabilizer bar is supported by the other of the pair of wheel holding portions and the vehicle body. Further, as the 1 or more cylinders, one cylinder is configured to: the volume of one of the two liquid chambers increases when the cylinder is extended, and decreases when the cylinder is retracted, and the volume of the other of the two liquid chambers decreases when the cylinder is extended, and increases when the cylinder is retracted.

In the single-cylinder type stabilizer described above, the expansion and contraction of one cylinder is restricted by achieving the state of interruption between the liquid chambers, and when the vehicle body rolls, the stabilizer bar is twisted as in the case of a normal stabilizer, and the reaction force of the twist acts between the left and right wheels and the vehicle body as a roll restraining force, thereby effectively restraining the roll of the vehicle body. On the other hand, by realizing the communication state between the liquid chambers, relatively free expansion and contraction of the cylinder is allowed, and, for example, road surface input to each of the left and right wheels in the case of field travel can be effectively absorbed. In addition, the single cylinder type stabilizer has a simple structure in that the presence/absence of the roll suppression effect is switched using only one cylinder, as compared to the double cylinder type stabilizer using a pair of cylinders.

The single-cylinder stabilizer may be provided for left and right wheels suspended by a rigid axle-type suspension, for example, and in this case, may be configured such that: the stabilizer bar is supported by an axle housing having a pair of wheel holding portions at both ends thereof, and both ends of the stabilizer bar are coupled to left and right portions of the vehicle body, respectively. The rigid axle type suspension device is suitable for a vehicle that travels outdoors due to the structural robustness. Therefore, by using the single-cylinder stabilizer capable of switching the presence or absence of the roll-restraining effect for the wheel suspended by the rigid axle-type suspension device, the vehicle can be a high-performance vehicle capable of traveling comfortably on a general road (relatively good road surface) as well as traveling in the open air.

In the stabilization system according to the present invention, for example, the two-cylinder type stabilizer may be disposed on one of the front wheel and the rear wheel, and the one-cylinder type stabilizer may be disposed on the other of the front wheel and the rear wheel. In addition, it is possible to arrange a two-cylinder type stabilizer for both the front wheel and the rear wheel, and to arrange a single-cylinder type stabilizer for both the front wheel and the rear wheel.

The stabilization system of the present invention may be configured as follows: when the 1 st and 2 nd stabilizing devices both achieve the inter-liquid-chamber cutoff state, the roll rigidity on the front-wheel side is higher than the roll rigidity on the rear-wheel side. When the roll rigidity is high, the difference in the ground contact load between the left and right wheels is large, and thus the lateral force or the side reaction force generated is small. Therefore, the vehicle mounted with the stabilizing system of the present embodiment tends to be understeered, and exhibits relatively stable turning behavior. Further, if the configuration is such that, at the time of an electrical failure, the roll suppression effect is exerted on one of the 1 st and 2 nd stabilizing devices provided for the front wheels and the roll suppression effect is not exerted on the other of the 1 st and 2 nd stabilizing devices provided for the rear wheels, it is possible to realize a vehicle that shows a relatively strong understeer tendency during turning at the time of an electrical failure.

The stabilization system of the present invention can be configured to be provided with a controller that manages control of the stabilization system. In this case, the controller may be configured to: in a situation where a vehicle equipped with this stabilization system is traveling outdoors or a situation where it is scheduled to travel outdoors, the active stabilization device realizes a state of communication between the liquid chambers. With this configuration, the stabilizer bar does not exert a rolling-restraining force during traveling in the open air, and effectively absorbs road surface input, so that the riding comfort during traveling in the open air is relatively good. Further, the controller may be configured to: the active stabilizer device is configured to realize the inter-liquid-chamber cutoff state, on the condition that the vehicle mounted with the stabilizer system is turned. With this configuration, the roll of the vehicle caused by the turning of the vehicle can be effectively suppressed.

Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals refer to like elements.

Drawings

Fig. 1 is a schematic view showing a stabilization system of an embodiment in which a stabilizer 1 is disposed with respect to a front wheel and a stabilizer 2 is disposed with respect to a rear wheel as an embodiment.

Fig. 2A is a diagram for explaining a structure relating to a held portion of a stabilizer bar constituting the 1 st stabilizer.

Fig. 2B is a diagram for explaining a supported portion of a stabilizer bar constituting the 1 st stabilizer.

Fig. 2C is a diagram for explaining the structure of a cylinder constituting the 1 st stabilizer.

Fig. 2D is a diagram for explaining the structure of a cylinder constituting the 1 st stabilizer.

Fig. 3A is a sectional view showing the structure of a shuttle valve included in the 1 st stabilizer.

Fig. 3B is a sectional view showing a structure of an opening/closing valve provided in the 2 nd stabilizer.

Fig. 4A is a schematic diagram for explaining the operation of the 1 st stabilizing device.

Fig. 4B is a schematic diagram for explaining the operation of the 1 st stabilizing device.

Fig. 5A is a schematic diagram for explaining the operation of the 2 nd stabilizing device.

Fig. 5B is a schematic diagram for explaining the operation of the 2 nd stabilizing device.

Fig. 6 is a flowchart showing a stabilization control routine executed by an Electronic Control Unit (ECU) as a controller of the stabilization system of the embodiment.

Detailed Description

Hereinafter, a vehicle stabilization system as an embodiment of the present invention will be described in detail with reference to the drawings as an embodiment for carrying out the present invention. The present invention can be implemented in various forms other than the following examples, by making various changes and improvements based on the knowledge of those skilled in the art, and also by making various changes and improvements, which are described in the items of the above [ forms of the present invention ].

[A] Structure of stabilizing system for vehicle

As schematically shown in fig. 1, the stabilizing system of the embodiment includes a 1 st stabilizing device 12 as the stabilizing device of the embodiment mounted on left and right front wheels 10FL, 10FR of the vehicle, and a 2 nd stabilizing device 14 mounted on left and right rear wheels 10RL, 10RR of the vehicle. When it is not necessary to distinguish between the left and right, the left and right front wheels 10FL and 10FR and the left and right rear wheels 10RL and 10RR may be referred to as front wheels 10F and rear wheels 10R, respectively, and when it is not necessary to distinguish between the front and rear, the left and right front wheels 10F and the left and right rear wheels 10R may be referred to as wheels 10, respectively.

i) 1 st stabilising arrangement

The front wheels 10FL and 10FR are suspended by a double-wishbone suspension device as an independently suspended suspension device. The 1 st stabilizer 12 is provided with a stabilizer bar 16 as a main structural element. The stabilizer bar 16 includes a central torsion bar portion 16t and left and right arm portions 16aL and 16aR integrated with each other, and the extending direction of the left and right arm portions 16aL and 16aR intersects the vehicle width direction which is the extending direction of the torsion bar portion 16 t. Both ends of the stabilizer bar 16, i.e., the front ends of the left and right arm portions 16aL, 16aR are coupled to the left and right lower arms 18L, 18R via links 20L, 20R, respectively.

The lower arms 18L, 18R hold the left and right front wheels 10F, respectively, and function as a pair of wheel holding portions that move up and down with respect to the vehicle body together with the held front wheels 10F. Although not shown, the other ends of the suspension spring and the damper, one end of which is supported by the mounting portion of the vehicle body, are connected to the lower arms 18L and 18R, respectively. Note that, a pair of left and right components such as the arm portions 16aL and 16aR and the lower arms 18L and 18R, which are denoted by a suffix L, R in the reference numerals, may be referred to as an arm portion 16a and a lower arm 18, when it is not necessary to distinguish between the left and right components.

To be described in detail later, a held portion 16h is provided at the center of the torsion bar portion 16t of the stabilizer bar 16 in the vehicle width direction, and the stabilizer bar 16 is held by a bracket 22 at the held portion 16h to a portion of the vehicle body (in the drawings, a portion of the vehicle body is shown in hatching) 24. As shown in fig. 2A, the holder 22 includes a held bush 26. The held portion bushing 26 includes an outer cylinder 26o and a rubber elastic body 26g interposed between the outer cylinder 26o and the torsion bar portion 16t of the stabilizer bar 16, and the stabilizer bar 16 is allowed to rotate about the held portion 16h (indicated by a hollow arrow in fig. 1). The held portion bushing 26 allows rotation, i.e., torsion, of the torsion bar portion 16t of the stabilizer bar 16 about the axis.

The 1 st stabilizer 12 includes a pair of cylinders 28L and 28R. In other words, the 1 st stabilizer 12 is a "two-cylinder type stabilizer" that supports the stabilizer bar 16 by a pair of cylinders 28L, 28R. The pair of cylinders 28L, 28R each have: a housing 28 h; a piston 28p disposed in the housing 28 h; and a piston rod 28r having a base end connected to the piston 28p and a tip end (lower end) extending downward from the housing 28h and passing through the liquid chamber. The housing 28h of each of the pair of cylinders 28L and 28R is fixedly coupled to the part 24 of the vehicle body, and the distal end portion of the piston rod 28R of each of the pair of cylinders 28L and 28R is coupled to a corresponding one of a pair of left and right supported portions 16sL and 16sR provided to the torsion bar portion 16t of the stabilizer bar 16 via a bearing 30.

As shown in fig. 2B, the support member 30 includes a supported portion bushing 32. The supported portion bushing 32 includes an outer cylinder 32o and a rubber elastic body 32g interposed between the outer cylinder 32o and the torsion bar portion 16t of the stabilizer bar 16. The supported portion bushing 32 allows rotation, that is, twisting, of the torsion bar portion 16t of the stabilizer bar 16 about the axis, as in the case of the held portion bushing 26.

As is clear from a comparison between fig. 2A and 2B, the rubber elastic body 26g of the supported portion bushing 26 is made thicker than the rubber elastic body 32g of the supported portion bushing 32. Since the rubber elastic bodies 32g and 26g are made of the same material, the spring constant in the vertical direction of the supported portion bushing 26 is made smaller than that of the supported portion bushing 32. That is, the held portion bushing 26 is made softer than the supported portion bushing 32. Therefore, the stabilizer bar 16 is firmly supported by the supported portions 16sL and 16sR, and the resistance to the rotation about the held portion 16h is relatively small.

As indicated by hollow arrows in fig. 1, each of the pair of cylinders 28L and 28R is capable of extending and contracting by vertical movement of a corresponding one of a pair of supported portions 16sL and 16sR provided on the right and left of the torsion bar portion 16t of the stabilizer bar 16, and the interior of the housing 28h is divided by the piston 28p into an upper chamber 28cU and a lower chamber 28cL which are two liquid chambers whose volumes fluctuate due to the extension and contraction. Specifically, the pair of cylinders 28L and 28R each have: the upper chamber 28cU as the 1 st liquid chamber increases the volume of the upper chamber 28cU when each cylinder extends, that is, when the corresponding front wheel 10F performs a rebound operation, and decreases the volume of the upper chamber 28cU when each cylinder contracts, that is, when the corresponding front wheel 10F performs a bounce operation; and a lower chamber 28cL as a 2 nd liquid chamber, wherein the volume of the lower chamber 28cL decreases when each cylinder is extended, and the volume of the lower chamber 28cL increases when each cylinder is contracted.

The 1 st stabilizer 12 includes: a 1 st communication passage 34 for communicating the upper chamber 28cU of the cylinder 28L with the lower chamber 28cL of the cylinder 28R; and a 2 nd communication passage 36 for communicating the lower chamber 28cL of the cylinder 28L with the upper chamber 28cU of the cylinder 28R. The 1 st stabilizer 12 includes an inter-passage communication passage 38 for communicating the 1 st communication passage 34 and the 2 nd communication passage 36 with each other, and an on-off valve 40 disposed in the inter-passage communication passage 38. The on-off valve 40 is a normally closed electromagnetic valve that is excited to open, and switches between communication and blocking of the inter-passage communication passage 38. The on-off valve 40 is opened to achieve a communication state between the passages in which the 1 st communication passage 34 and the 2 nd communication passage 36 communicate with each other, and the on-off valve 40 is closed to achieve a non-communication state between the passages in which the 1 st communication passage 34 and the 2 nd communication passage 36 do not communicate with each other.

In other words, the 1 st stabilizer 12 includes two hydraulic systems each connecting the upper chamber 28cU of one cylinder 28 and the lower chamber 28cL of the other cylinder 28 via a cross pipe, which is formed by using the 1 st communication passage 34 and the 2 nd communication passage 36 as cross pipes, and further includes a switching mechanism configured to include the inter-passage communication passage 38 and the on-off valve 40, that is, a switching mechanism for selectively achieving an inter-passage communication state and an inter-passage non-communication state, as regards the communication between the two hydraulic systems.

Further, it is considered that the present 1 st stabilizer 12 is provided with one communication passage for communicating the upper chamber 28cU and the lower chamber 28cL of each cylinder 28 with the 1 st communication passage 34, the 2 nd communication passage 36, and the inter-passage communication passage 38. From this recognition, it is considered that the open/close valve 40 is set to the open state, and the liquid chamber communication state in which the upper chamber 28cU and the lower chamber 28cL communicate with each other is realized in each cylinder 28, and the liquid chamber blocking state in which the upper chamber 28cU and the lower chamber 28cL are blocked from each other is realized in each cylinder 28 by setting the open/close valve 40 to the closed state.

As will be described in detail later, the cylinders 28L and 28R are cylinders in which piston rods extend only from one side, so-called "rod-one-side extending cylinders", and the total of the internal volume of the casing 28h, that is, the volume of the upper chamber 28cU and the volume of the lower chamber 28cL, changes as the cylinder extends and contracts. In other words, the outflow/inflow amount of the working fluid to the upper chamber 28cU and the outflow/inflow amount of the working fluid to the lower chamber 28cL are different from each other with expansion and contraction. To compensate for this difference, that is, the change in the volume of the cylinders 28L and 28R, the 1 st communication passage 34 and the 2 nd communication passage 36 are connected to an accumulator 48 provided in the 2 nd stabilizer 14 via the non-electromagnetic shuttle valve 42, the orifice 44, and the inter-device communication passage 46. The 1 st stabilizer 12 is provided with an injection port 50 for injecting the working fluid. The injection port 50 is common to the 1 st stabilizer 12 and the 2 nd stabilizer 14, and injects the liquid into the 2 nd stabilizer 14 through the inter-device communication path 46. The 3 valves 52 are normally closed and opened when the working fluid is injected from the injection port 50.

ii) the 2 nd stabilizing device

The rear wheels 10RL, 10RR are suspended by rigid axle type suspension devices, and the 2 nd stabilizer 14 is provided with respect to these rear wheels 10RL, 10 RR. The 2 nd stabilizer 14 includes a stabilizer 60 as a main component, as in the 1 st stabilizer 12. The stabilizer bar 60 of the 2 nd stabilizer apparatus 14 is also configured to include a central torsion bar portion 60t and left and right arm portions 60aL, 60aR integrated with each other, and the extending direction of the left and right arm portions 60aL, 60aR intersects the vehicle width direction which is the extending direction of the torsion bar portion 60 t.

The torsion bar portion 60t of the stabilizer 60 is provided with supported portions 60sL, 60sR on the left and right, and the stabilizer 60 is supported by the axle housing 62 via a bearing 64 at the supported portions 60sL, 60 sR. The axle case 62 functions as a wheel holding portion that holds the rear wheels 10RL and 10RR at both ends thereof, respectively, and is swingable as indicated by hollow arrows in fig. 1 in accordance with vertical movement of the rear wheels 10RL and 10RR with respect to the vehicle body. Although not shown, the bearing 64 has a supported portion bush configured to include an outer cylinder and a rubber elastic body, and allows rotation, that is, torsion, about the axis of the torsion bar portion 60t of the stabilizer 60, similarly to the bearing 30 of the stabilizer 12 1 described above.

Both ends of stabilizer bar 60, that is, the front ends of left and right arm portions 60aL, 60aR are coupled to one portion 24 of the vehicle body, specifically, to portions positioned on the left and right in the vehicle width direction. Specifically, the front end of the right arm portion 60aR is coupled via a link 66, and the front end of the left arm portion 60aL is coupled via links 68 and 70 and a cylinder 72. That is, the 2 nd stabilizer 14 is a "single-cylinder type stabilizer" in which one cylinder 72 is used for connection of the stabilizer 60.

The cylinder 72 is similar to the cylinder 28 of the 1 st stabilizer 12, and includes: a housing 72 h; a piston 72p disposed in the housing 72 h; and a piston rod 72r having a base end connected to the piston 72p and a tip end (lower end) extending downward from the housing 72h through the liquid chamber. The housing 72h is swingably supported to the part 24 of the vehicle body via a bushing, one end of the link 68 is connected to the tip end of the arm portion 60aL, the other end of the link 68 is connected to one end of the link 70, and the other end of the link 70 is connected to the housing 72h of the cylinder 72. Further, by coupling the front end of the piston rod 72r to the intermediate portion of the link 68, the front end of the piston rod 72r is simply coupled to the front end of the left arm portion 60aL of the stabilizer 60, that is, one end of the stabilizer 60.

As indicated by hollow arrows in fig. 1, the cylinder 72 is capable of expanding and contracting in accordance with the swing of the axle case 62, that is, the rebound operation and the bound operation of the rear wheel 10RL, and the interior of the housing 70h is divided by the piston 72p into an upper chamber 72cU and a lower chamber 72cL, which are two liquid chambers whose volumes change by expansion and contraction, in the same manner as the cylinder 28 of the first stabilizer 12. Specifically, the cylinder 72 includes: the upper chamber 72cU, which is the 1 st liquid chamber, has an increased volume when expanded and a decreased volume when contracted; and a lower chamber 72cL as a 2 nd liquid chamber, the volume of which decreases when it extends and increases when it contracts.

The 2 nd stabilizer 14 includes an inter-chamber communication passage 74 for communicating the upper chamber 72cU and the lower chamber 72cL of the cylinder 72, and the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78 are arranged in series with each other in the inter-chamber communication passage 74. The 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78 will be described later in detail, but are non-electromagnetic pilot valves that operate using the pressure of the working fluid introduced through the inter-device communication passage 46 as a pilot pressure, and change from an open state to a closed state when the pressure increases to a set pressure or more. When both the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78 are in the open state, the liquid chamber communication state in which the upper chamber 72cU and the lower chamber 72cL communicate with each other is achieved, and the liquid chamber cutoff state in which the upper chamber 72cU and the lower chamber 72cL are cut off is achieved by closing both the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78. In other words, the 2 nd stabilizing device 14 includes a switching mechanism configured to include the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78, that is, a switching mechanism for selectively achieving a state of communication between the liquid chambers and a state of blocking between the liquid chambers.

Note that, although the details will be described later, the cylinder 72 is a so-called rod one-side extending cylinder, similarly to the cylinder 28 of the 1 st stabilizer 12, and the internal volume of the casing 72h, that is, the total of the volume of the upper chamber 72cU and the volume of the lower chamber 72cL, changes as the cylinder extends and contracts. In other words, the outflow/inflow amount of the working fluid to the upper chamber 72cU and the outflow/inflow amount of the working fluid to the lower chamber 72cL are different from each other with respect to expansion and contraction. In order to compensate for this difference, that is, the change in the volume of the cylinder 72, in the 2 nd stabilizer 14, the accumulator 48 described above is connected to the inter-chamber communication passage 74 between the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78. To explain this accumulator 48, the accumulator 48 functions as both an accumulator necessary for the 1 st stabilizer 12 and an accumulator necessary for the 2 nd stabilizer 14, and is a component common to the 1 st stabilizer 12 and the 2 nd stabilizer 14. As a result, the number of accumulators is reduced in the present stabilization system. Further, it is considered that the hydraulic systems of the 1 st stabilizer 12 and the 2 nd stabilizer 14 are coupled to each other in the present stabilizer system by the inter-device communication path 46 described above.

As described above, the injection of the working fluid into the 2 nd stabilizer 14 is also performed from the injection port 50 provided in the 1 st stabilizer 12 through the inter-device communication passage 46. That is, the injection port 50 may be considered as a single injection port common to the 1 st and 2 nd stabilizing devices 12 and 14, and by using this injection port 50, the working fluid can be injected easily in the present stabilizing system.

The torsion bar portion 60t of the stabilizer bar 60 of the present 2 nd stabilizer apparatus 14 is supported by the axle case 62, and the front ends of the arm portions 60aL and 60aR are coupled to the portion 24 of the vehicle body. In the present stabilization system, instead of such a stabilizer device, a stabilizer device having a structure in which the torsion bar portion of the stabilizer bar 60 is supported by the vehicle body and the respective front ends of the pair of arm portions are coupled to both ends of the axle housing may be employed.

iii) linkage mechanism

In the present stabilization system, a link mechanism is provided that links the 2 nd stabilizer 14 and the 1 st stabilizer 12 with the 1 st stabilizer 12 as a "master stabilizer" and the 2 nd stabilizer 14 as a "slave stabilizer". Specifically, a mechanism is provided for realizing the inter-liquid-chamber shut-off state also in the 2 nd stabilizing device 14 when the 1 st stabilizing device 12 realizes the inter-passage non-communicating state, i.e., the inter-liquid-chamber shut-off state.

Specifically, the shuttle valve 42 included in the first stabilizer 12 is a shuttle valve having the structure shown in fig. 3A, and includes a housing 42h, 3 ports 42p1, 42p2, and 42p3 formed in the housing 42h, 3 liquid chambers 42c1, 42c2, and 42c3 partitioned and formed in the housing 42h and communicating with the ports 42p1, 42p2, and 42p3, respectively, and a valve mechanism 42v selectively connecting these liquid chambers 42c1, 42c2, and 42c 3. The port 42p1 is connected to the 1 st communication path 34, the port 42p2 is connected to the 2 nd communication path 36, and the port 42p3 is connected to the inter-device communication path 46. The valve mechanism 42v has a valve ball 42b, and moves left and right by a difference between the pressure of the working fluid in the fluid chamber 42c1 and the pressure of the working fluid in the fluid chamber 42c 2. When the pressure of the working fluid in the fluid chamber 42c1 is high, that is, when the pressure of the 1 st hydraulic system including the upper chamber 28cU of the cylinder 28L and the lower chamber 28cL of the cylinder 28R connected through the 1 st communication passage 34 is higher than the pressure of the 2 nd hydraulic system including the upper chamber 28cU of the cylinder 28R and the lower chamber 28cL of the cylinder 28L connected through the 2 nd communication passage 36, the valve ball 42b moves rightward, the 1 st hydraulic system and the inter-device communication passage 46 are communicated, and the 2 nd hydraulic system and the inter-device communication passage 46 are blocked. Conversely, when the pressure of the hydraulic fluid in the fluid chamber 42c2 is high, that is, when the pressure of the 2 nd hydraulic system is higher than the pressure of the 1 st hydraulic system, the valve ball 42b moves leftward, communicates the 2 nd hydraulic system with the inter-device communication path 46, and blocks the 1 st hydraulic system from the inter-device communication path 46. Further, a filter 42f for preventing passage of foreign matter is disposed in each of the liquid chambers 42c1, 42c2, and 42c3 of the shuttle valve 42.

According to the above-described operation, the shuttle valve 42 functions as a non-electromagnetic switching valve for introducing one of the pressures of the two hydraulic systems of the 1 st stabilizer 12, specifically, a higher pressure of one of the upper chamber 28cU and the lower chamber 28cL of the cylinders 28L and 28R, to the 2 nd stabilizer 14 via the inter-device communication passage 46. In connection with this function, the inter-device communication passage 46 functions as an introduction passage for introducing the higher pressure of one of the upper chamber 28cU and the lower chamber 28cL of the cylinders 28L and 28R of the 1 st stabilizer 12 into the 2 nd stabilizer 14.

On the other hand, the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78 of the 2 nd stabilizer 14 are opening/closing valves having the structure shown in fig. 3B, and include a housing 76h, a piston 76p disposed in the housing 76h, a pilot pressure chamber 76cP formed to divide the base end side of the piston 76p, two ports 76pU and 76pL connected to the upper chamber 72cU and the lower chamber 72cL of the cylinder 72, respectively, and a port 76pP for introducing the working fluid into the pilot pressure chamber 76 cP. The piston 76p is biased toward the proximal end side by the spring 76s, and when the hydraulic pressure introduced from the 1 st stabilizer 12 via the inter-device communication path 46 exceeds a set pressure, the piston 76p moves toward the distal end side, and the two ports 76pU and 76pL are blocked. That is, the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78 are non-electromagnetic valves that operate using the introduced hydraulic pressure as a pilot pressure.

In a state where the two ports 76pU and 76pL of the two opening/closing valves 76 and 78 are communicated with each other, a liquid-chamber communication state is achieved in which the upper chamber 72cU and the lower chamber 72cL of the cylinder 72 are communicated with each other. In a state where the hydraulic pressure introduced from the 1 st stabilizer 12 exceeds the set pressure and blocks the space between the two ports 76pU and 76pL of the two opening/closing valves 76 and 78, the upper chamber 72cU and the lower chamber 72cL of the cylinder 72 are blocked from each other.

In the case where the opening/closing valve 40 is in the valve-closed state in the 1 st stabilizer 12 as the active stabilizer, the inter-liquid-chamber blocked state is realized as described above. As will be described in detail later, when the 1 st stabilizer 12 is in the inter-liquid-chamber blocked state, for example, when one of the left and right front wheels 10F performs a bounce operation or a rebound operation, the hydraulic pressure of the 1 st hydraulic system or the 2 nd hydraulic system is increased. The increased hydraulic pressure is introduced into the 2 nd stabilizer 14 as a driven stabilizer via the shuttle valve 42 and the inter-device communication passage 46, and the introduced hydraulic pressure acts as a pilot pressure on the 1 st on-off valve 76 and the 2 nd on-off valve 78 of the 2 nd stabilizer 14. By the action of the pilot pressure, the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78 are brought into the closed state, and the above-described liquid chamber shut-off state is also achieved in the 2 nd stabilizing device 14. As can be seen from this operation, in the present stabilization system, the interlocking mechanism is configured to include the shuttle valve 42, the inter-device communication path 46 as the introduction path, the 1 st opening/closing valve 76 as the pilot valve, the 2 nd opening/closing valve 78, and the like, and when the active stabilization device achieves the inter-liquid-chamber blocked state, the driven stabilization device also achieves the inter-liquid-chamber blocked state. Further, a orifice 44 is provided to alleviate a rapid change in the pilot pressure, and the orifice 44 is provided on the 2 nd stabilizing device 14 side of the shuttle valve 42 in the inter-device communication passage 46.

The inter-device communication passage 46 branches into a pilot introduction passage 46p and an accumulator communication passage 46a, and pilot pressure is introduced from the pilot introduction passage 46p into the respective ports 76pP of the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78. The shutoff valve 80 and the orifice 82, which are normally open electromagnetic valves, are disposed in the accumulator communication passage 46a, and the working fluid from the 1 st stabilizer 12 flows to the accumulator 48 in a state where the shutoff valve 80 is not excited, and the pilot pressure is not introduced into the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78, respectively. Therefore, in the present stabilization system, when the 2 nd stabilizer 14 is interlocked with the 1 st stabilizer 12 as described above, that is, when both the 1 st stabilizer 12 and the 2 nd stabilizer 14 are set to the inter-liquid-chamber cutoff state, the shut valve 80 is excited to the closed valve state. The orifice 82 is provided to restrict the inflow of the working fluid from the 1 st stabilizer 12 to the accumulator 48 and the outflow of the working fluid from the accumulator 48 to the 1 st stabilizer 12.

[B] Operation of the stabilizing system

Hereinafter, the operation of the present stabilization system will be described with respect to each of the 1 st and 2 nd stabilization devices 12 and 14.

i) 1 st stabilising arrangement

As described above, when the on-off valve 40 constituting the switching mechanism of the 1 st stabilizing device 12 is set to the valve-closed state, the inter-passage non-communication state in which the 1 st communication passage 34 and the 2 nd communication passage 36 are not in communication, that is, the inter-liquid-chamber blocked state in which the upper chamber 28cU and the lower chamber 28cL of the cylinders 28L and 28R are blocked from each other is realized. As shown in fig. 2C, the cylinder 28 is a so-called "rod-one-side-extending cylinder", and the amount of change in volume of the upper chamber 28cU due to expansion and contraction is different from the amount of change in volume of the lower chamber 28cL because the piston rod 28r penetrates the lower chamber 28cL but the piston rod does not penetrate the upper chamber 28 cU. Therefore, in the inter-passage non-communication state, that is, the inter-liquid-chamber blocked state, the working fluid does not flow out and in between the upper chamber 28cU of the cylinder 28L and the lower chamber 28cL of the cylinder 28R through the 1 st communication passage 34, and the working fluid does not flow out and in between the upper chamber 28cU of the cylinder 28R and the lower chamber 28cL of the cylinder 28L through the 2 nd communication passage 36. That is, both cylinders 28L, 28R are prohibited from extending and contracting.

As shown in fig. 4A, when the vehicle turns, the vehicle body tilts, i.e., rolls, in the left-right direction. Fig. 4A shows a state in which the vehicle body is tilted to the right while turning to the left. In a state where the extension and contraction of the cylinders 28L and 28R are prohibited, the supported portions 16sL and 16sR of the torsion bar portion 16t of the stabilizer bar 16 supported by the front ends of the piston rods 28R of the cylinders 28L and 28R are prohibited from moving up and down with respect to the vehicle body, and therefore the torsion bar portion 16t is twisted. The torsional reaction force acts on the lower arms 18L, 18R via the left and right arm portions 16aL, 16aR, thereby suppressing the roll of the vehicle body. That is, the vehicle body roll suppressing effect is exhibited.

On the other hand, as shown in fig. 4B, when the on-off valve 40 is set to the open state, the inter-passage communication state in which the 1 st communication passage 34 and the 2 nd communication passage 36 communicate with each other, that is, the inter-liquid-chamber communication state in which the upper chamber 28cU and the lower chamber 28cL of the cylinders 28L and 28R communicate with each other is realized, and substantially free inflow and outflow of the working fluid to and from the upper chamber 28cU and the lower chamber 28cL of the cylinders 28L and 28R are permitted. Both cylinders 28L, 28R are allowed to expand and contract almost without restriction.

As shown in fig. 4B, a case where an external input acts on the left and right front wheels 10FL, 10FR while allowing expansion and contraction of the cylinders 28L, 28R is considered. Fig. 4B shows a case where an external input such as a rebound operation of the left front wheel 10FL and a bounce operation of the right front wheel 10FR is applied when the vehicle is traveling in the open air (a place where the ground surface is uneven). In this case, since the supported portions 16sL and 16sR of the stabilizer bar 16 are allowed to move up and down with respect to the vehicle body, the stabilizer bar 16 rotates in accordance with the up-and-down movement (strictly, the relative up-and-down movement) of the left and right front wheels 10FL and 10 FR. Specifically, the cylinders 28L and 28R extend and contract during the rebound operation and the bound operation of the left and right front wheels 10FL and 10FR, and allow the stabilizer bar 16 to rotate. The stabilizer bar 16 is hardly twisted by the vertical movement of the supported portions 16sL, 16sR of the stabilizer bar 16 accompanying this rotation. That is, the stabilizer bar 16 does not urge the lower arms 18L, 18R. That is, the body-roll restraining effect is nullified. Therefore, even when traveling on an uneven ground, the road surface input to each of the left and right front wheels 10FL, 10FR can be effectively absorbed.

As described above, the cylinder 28 employed in the first stabilizer 12 is a so-called "rod-one-side extending cylinder" as shown in fig. 2C, that is, a cylinder in which the piston rod 28r extends through the lower chamber 28cL, which is one of the two liquid chambers. Therefore, when the pressure receiving area SU of the piston 28p on which the pressure of the working fluid in the upper chamber 28cU acts is compared with the pressure receiving area SL of the piston 28p on which the pressure of the working fluid in the lower chamber 28cL acts, the pressure receiving area SU becomes large. Therefore, when the pressure of the hydraulic fluid in the upper chamber 28cU is equal to the pressure of the hydraulic fluid in the lower chamber 28cL, the piston 28p receives a downward force, and the cylinder 28 is extended. Such extension of the cylinder 28 may be accompanied by a so-called cavitation phenomenon, and may cause a problem particularly in a case where the passages communicate with each other, that is, the liquid chambers communicate with each other. With the present 1 st stabilizer 12, the stabilizer bar 16 is held by the bracket 22 at the held portion 16h, and therefore the above-described elongation caused by the cylinder 28 being a bar one-side extending cylinder is effectively prevented.

Instead of the cylinder 28, a cylinder 28' as shown in fig. 2D, that is, a so-called "rod both-side projecting cylinder" may be used. In the cylinder 28 ', the pressure receiving area SL is equal to the pressure receiving area SU, and the cylinder 28' does not extend as described above. However, there are disadvantages that a complicated structure such as sealing of the working fluid is required and the installation space of the cylinders is required to be long, and even if the opening/closing valve 40 is in the closed state, one of the pair of cylinders 28 'is allowed to extend by a certain amount and the other contracts by the same amount, so that it is necessary to take special consideration to effectively inhibit the extension of both of the pair of cylinders 28'. In addition, in the case of using the rod-side extension cylinder, the accumulator 48 can be omitted without causing a change in the internal volume of the casing 28h accompanying the expansion and contraction as described above, in other words, without causing a difference between the inflow and outflow amounts of the working fluid to the upper chamber 28cU and the outflow and inflow amounts of the working fluid to the lower chamber 28cL accompanying the expansion and contraction.

ii) operation of the 2 nd stabilising means

As described above, when both the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78 constituting the switching mechanism of the 2 nd stabilizing device 14 are in the valve-closed state, the liquid chamber cutoff state is realized in which the upper chamber 72cU and the lower chamber 72cL of the cylinder 72 are cut off from each other. In this state, the inflow and outflow of the working fluid to and from the upper chamber 72cU and the lower chamber 72cL are prohibited, and the expansion and contraction of the cylinder 72 are prohibited.

As shown in fig. 5A, when the vehicle turns, the vehicle body tilts, i.e., rolls, in the left-right direction. Fig. 5A shows a state where the vehicle body is tilted to the right while turning to the left. Due to the vehicle body tilting, the axle housing 62 that supports the torsion bar portion 60t of the stabilizer bar 60 at the supported portions 60sL, 60sR swings relative to the vehicle body. In a state where the extension and contraction of the cylinder 72 are prohibited, the positions of the arms 60aL and 60aR of the stabilizer 60 in the vertical direction with respect to the vehicle body are not substantially changed. Therefore, the torsion bar portion 60t of the stabilizer bar 60 is twisted by the oscillation of the axle case 62. The reaction force of the torsion acts on the part 24 of the vehicle body via the left and right arm portions 60aL, 60aR and the cylinder 72, thereby suppressing the roll of the vehicle body. Namely, the vehicle body roll restraining effect is exerted.

On the other hand, as shown in fig. 5B, when both the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78 are in the open state, the state of communication between the liquid chambers in which the upper chamber 72cU and the lower chamber 72cL of the cylinder 72 communicate with each other is achieved, and substantially free inflow and outflow of the working liquid to and from the upper chamber 72cU and the lower chamber 72cL is allowed. The cylinder 72 is allowed to expand and contract almost without restriction.

As shown in fig. 5B, a case where an external input acts on the left and right rear wheels 10RL and 10RR while allowing expansion and contraction of the cylinder 72 is considered. Fig. 5B shows a case where an external input such as a rebound operation of the left rear wheel 10RL and a bounce operation of the right rear wheel 10RR is applied in the field. In this case, the axle case 62 swings, and the stabilizer bar 60 supported by the axle case 62 on the supported portions 60sL and 60sR also swings due to the swing. However, since the expansion and contraction of the cylinder 72 are permitted, the torsion bar portion 60t of the stabilizer bar 60 is hardly twisted even by the oscillation of the stabilizer bar 60. That is, the stabilizer 60 does not urge the axle housing 62 to swing with respect to the vehicle body. That is, the body roll restraining effect is nullified. Therefore, even when traveling on an uneven ground, the road surface input to each of the left and right rear wheels 10RL, 10RR can be effectively absorbed.

iii) roll rigidity provided by the stabilizer

As described above, the 1 st stabilizer 12 exhibits the vehicle body roll suppression effect when the liquid-chamber cutoff state is achieved, and the 2 nd stabilizer 14 exhibits the vehicle body roll suppression effect when the liquid-chamber cutoff state is achieved. To describe the extent of the exertion of the roll suppression effect, the 1 st and 2 nd stabilizing devices 12, 14 are configured such that the roll rigidity on the front wheel 10F side is higher than the roll rigidity on the rear wheel 10R side when both the 1 st and 2 nd stabilizing devices 12, 14 exert the roll suppression effect. With this configuration, the vehicle tends to be under-steered and exhibits a stable turning behavior.

iv) operation in the event of electrical failure

When an electrical failure occurs, in other words, when a failure occurs in which electric power cannot be supplied to the on-off valve 40 of the 1 st stabilizing device 12 and the off-off valve 80 of the 2 nd stabilizing device 14, which are electromagnetic valves, respectively, the on-off valve 40, which is a normally closed electromagnetic valve, is in a closed state, and the off-off valve 80, which is a normally open electromagnetic valve, is in an open state. As a result, although the inter-liquid-chamber blocked state is achieved in the 1 st stabilizing device 12, the pilot pressure from the 1 st stabilizing device 12 via the inter-device communication path 46 does not act on the 1 st on-off valve 76 and the 2 nd on-off valve 78 of the 2 nd stabilizing device 14, and the inter-liquid-chamber communication state is achieved in the 2 nd stabilizing device 14. That is, although the first stabilizer device 12 exerts the body roll suppression effect, the second stabilizer device 14 negates the body roll suppression effect. Therefore, the roll rigidity on the front wheel 10F side becomes high, and the roll rigidity on the rear wheel 10R side becomes low. Therefore, the vehicle exhibits a tendency to understeer even at the time of an electrical failure.

Further, at the time of an electrical failure, although the 1 st stabilizer 12 is in the liquid-chamber cutoff state, the 1 st stabilizer 12 is allowed to flow out and in between the cylinders 28L, 28R of the 1 st stabilizer 12 and the accumulator 48, and more specifically, the flow of the working fluid is allowed along with the resistance of the orifice 44 and the orifice 82, so that the vehicle-body-roll suppressing effect of the 1 st stabilizer 12 is lower than that in the case where the shut-off valve 80 of the 2 nd stabilizer 14 is in the valve-closed state.

[3] Control of a stabilization system

The control of the present stabilization system is executed by a stabilization electronic control unit (hereinafter, referred to as "ECU" in some cases; see fig. 1) 90 as a controller. Specifically, the ECU90 executes the energization control to the on-off valve 40 of the 1 st stabilizer 12 and the off-valve 80 of the 2 nd stabilizer 14. The ECU90 is configured to include a computer having a CPU, ROM, RAM, and the like, and a drive circuit (driver) for opening and closing the valve 40 and the shut-off valve 80.

In the present stabilization system, the ECU90 switches the inter-liquid chamber communication state and the inter-liquid chamber cutoff state of each of the 1 st and 2 nd stabilization devices 12, 14 according to the running state of the vehicle.

Specifically, as one of the situation in which the field travel is being performed and the situation in which the field travel is scheduled, in the latter situation, the 1 st stabilizing device 12 is excited to open the valve 40 to establish the state of communication between the liquid chambers, and the 2 nd stabilizing device 14 is excited to maintain the open state without exciting the closing valve 80 to maintain the open state, thereby prohibiting the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78 from being in the closed state, and as a result, maintaining the state of communication between the liquid chambers. That is, the vehicle body roll restraining effect is nullified on both the front wheel 10F side and the rear wheel 10R side.

The vehicle mounted with the present stabilization system is a vehicle suitable for traveling outdoors, and when traveling outdoors or on a general road, the mode of the transmission of the drive system is switched by the selection of the driver. Whether the vehicle is scheduled to travel outdoors is determined based on whether the mode of the transmission is set to the outdoors travel mode. In addition, in a situation where the vehicle is actually traveling in the open air, the liquid chamber communication state may be realized between both the 1 st stabilizer 12 and the 2 nd stabilizer 14, but in this case, for example, it is sufficient to determine whether or not the vehicle is actually traveling in the open air based on the degree of change in the sprung acceleration detected by an sprung acceleration sensor or the like provided in the vehicle body.

When the situation is not the situation in which the field travel is scheduled, the ECU90 turns the on-off valve 40 off when the degree of turning of the vehicle (for example, the severity) exceeds a set degree, and turns the on-off valve 40 off to a closed state, thereby achieving the state of blocking between the liquid chambers, and turns the off valve 80 off to a closed state in the 2 nd stabilizing device 14, thereby allowing the on-off valve 76, 78 of the 1 st on-off valve and allowing the state of blocking between the liquid chambers to be achieved due to the pilot pressure. In brief, the ECU90 realizes the inter-liquid-chamber cutoff state in both the 1 st stabilizer 12 and the 2 nd stabilizer 14, with the vehicle turning as a requirement.

Whether or not the degree of turning of the vehicle exceeds the set degree may be determined based on the amount of operation of the steering operation member (the operation angle of the steering wheel), the operation speed of the steering operation member (the operation speed of the steering wheel), the steering amount of the wheels, the steering speed of the wheels, the vehicle running speed, the lateral acceleration of the vehicle body, the yaw rate of the vehicle, and the like. In the present stabilization system, specifically, it is determined that the degree of turning of the vehicle exceeds the set degree when one of a) a value obtained by dividing the lateral acceleration Gy by the operation amount (operation angle) θ of the operation member exceeds the threshold value a and B) a change speed (steering speed) d θ of the operation amount θ of the operation member exceeds the threshold value speed B is satisfied.

Specifically, the ECU90 controls the stabilization system by repeatedly executing the stabilization control routine shown in the flowchart of fig. 6 at short time intervals (for example, several to several tens of msec). Hereinafter, the process according to this procedure will be briefly described.

In the process according to the stability control routine, first, at S1, it is determined whether the mode of the transmission is the field travel mode. In the case of the field travel mode, in S2, the 1 st stabilizing device 12 excites the opening/closing valve 40 to open the valve, thereby establishing the communication state between the liquid chambers, and the 2 nd stabilizing device 14 does not excite the closing valve 80 to maintain the open valve, thereby maintaining the open valve state of the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78, thereby establishing the communication state between the liquid chambers.

If it is determined in S1 that the vehicle is not in the field travel mode, the turning degree specifying process of S3 is executed. Specifically, the lateral acceleration Gy, the operation amount θ of the operation member, and the steering speed d θ are determined. Next, at S4, it is determined whether or not the value obtained by dividing the lateral acceleration Gy by the operation amount θ of the operation member exceeds the threshold value a, and at S5, it is determined whether or not the steering speed d θ exceeds the threshold speed B. When at least one of a condition that a value obtained by dividing the lateral acceleration Gy by the operation amount θ of the operation member exceeds the threshold value a and a condition that the steering speed d θ exceeds the threshold value B is satisfied, the 1 st stabilizing device 12 realizes the inter-liquid-chamber block state by maintaining the valve-closed state without exciting the opening/closing valve 40 at S6, and the 2 nd stabilizing device 14 excites the closing valve 80 to the valve-closed state, thereby allowing the valve-closed state by the pilot pressures of the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78 to realize the inter-liquid-chamber block state. When neither of the conditions of S4 and S5 is satisfied, in S2, the 1 st stabilizing device 12 is excited to open the valve 40 to achieve the inter-liquid-chamber communication state, and the 2 nd stabilizing device 14 is not excited to maintain the valve 80 in the open state to maintain the 1 st opening/closing valve 76 and the 2 nd opening/closing valve 78 in the open state to achieve the inter-liquid-chamber communication state.