阅读说明：本技术 缓冲器 (Buffer device ) 是由 岛内壮大 粟野宏一郎 植村将史 于 2020-02-28 设计创作，主要内容包括：缓冲器(A)具备：硬质侧阻尼元件(FH),其对在伸长侧腔室(L1)和压缩侧腔室(L2)之间移动的液体的流动施加阻力；电磁阀(V),其可以对绕过硬质侧阻尼元件与伸长侧腔室(L1)和压缩侧腔室(L2)连通的旁路通道(B)的开口面积进行变更；软质侧阻尼元件(FS),其与电磁阀(V)串联地设置在旁路通道(B)上；以及储液罐(T),其连接压缩侧腔室(L2)；其中,硬质侧阻尼元件(FH)构成为具有节流孔(22)以及与其并列的硬质叶片阀(20,21),软质侧阻尼元件(FS)构成为具有开口面积比节流孔(22)大的节流孔(52)。(A buffer (A) is provided with: a hard side damping element (FH) that applies resistance to the flow of liquid moving between the expansion side chamber (L1) and the compression side chamber (L2); a solenoid valve (V) capable of changing the opening area of a bypass passage (B) that bypasses the hard-side damping element and communicates with the expansion-side chamber (L1) and the compression-side chamber (L2); a soft side damping element (FS) provided on the bypass passage (B) in series with the solenoid valve (V); and a reservoir tank (T) connected to the compression-side chamber (L2); wherein the hard side damping element (FH) is configured to have an orifice (22) and hard leaf valves (20, 21) arranged in parallel therewith, and the soft side damping element (FS) is configured to have an orifice (52) having a larger opening area than the orifice (22).)

1. A kind of buffer is disclosed, which comprises a buffer body,

it is provided with:

a cylinder;

a piston inserted into the cylinder movably in an axial direction and dividing the cylinder into an extension-side chamber and a compression-side chamber;

a piston rod having one end connected to the piston and the other end protruding out of the cylinder;

a liquid storage tank connected to the compression-side chamber and pressurizing the inside of the cylinder;

a hard-side damping element that applies resistance to a flow of liquid that moves between the extension-side chamber and the compression-side chamber;

a solenoid valve capable of changing an opening area of a bypass passage that bypasses the hard side damping element and communicates with the expansion side chamber and the compression side chamber;

and a soft-side damping element provided on the bypass passage in series with the solenoid valve;

wherein the hard side damping element is configured to have an orifice and a hard leaf valve provided in parallel with the orifice,

the soft-side damping element is configured to have a large-diameter orifice having an opening area larger than that of the orifice.

2. The buffer of claim 1, wherein the buffer is a single buffer,

wherein the content of the first and second substances,

the soft-side damping element is configured to have a leaf valve disposed in parallel with the large-diameter orifice.

3. The buffer of claim 1, wherein the buffer is a single buffer,

wherein the content of the first and second substances,

the opening degree of the electromagnetic valve is changed in proportion to the amount of energization.

4. The buffer of claim 1, wherein the buffer is a single buffer,

wherein the content of the first and second substances,

the electromagnetic valve has: a cylindrical holder formed with a port connected to the bypass passage; a valve core which can be inserted into the bracket in a reciprocating way and can open and close the port; an urging spring that urges the valve body in one direction of movement of the valve body; and a solenoid that applies a thrust force to the valve body in a direction opposite to the biasing force of the biasing spring.

5. The buffer of claim 2, wherein the buffer is a single buffer,

wherein the content of the first and second substances,

the leaf valve as the hard-side damping element is provided with: an extension-side hard leaf valve that applies resistance to the flow of liquid from the extension-side chamber to the compression-side chamber; and a compression-side hard leaf valve that applies resistance to the flow of liquid from the compression-side chamber to the extension-side chamber;

the leaf valve as the soft-side damping element is provided with: an extension-side soft leaf valve that applies resistance to a flow of liquid flowing from the extension-side chamber to the compression-side chamber in the bypass channel; and a compression-side soft leaf valve that applies resistance to a flow of liquid flowing from the compression-side chamber to the extension-side chamber in the bypass passage.

6. The buffer of claim 2, wherein the buffer is a single buffer,

wherein the content of the first and second substances,

the leaf valve as the hard-side damping element is provided with: an extension-side hard leaf valve that applies resistance to the flow of liquid from the extension-side chamber to the compression-side chamber; and a compression-side hard leaf valve that applies resistance to the flow of liquid from the compression-side chamber to the extension-side chamber;

the leaf valve as the soft-side damping element is provided only with an extension-side soft valve that applies resistance to the flow of the liquid flowing from the extension-side chamber to the compression-side chamber in the bypass passage.

7. The buffer of claim 4, wherein the buffer is a single buffer,

wherein the content of the first and second substances,

the spool moves along a straight line orthogonal to a central axis passing through the center of the piston rod.

8. The buffer according to any one of claims 1 to 7,

wherein the content of the first and second substances,

a casing for accommodating the solenoid valve and the soft-side damping element is provided inside the soft-side damping element,

and the housing is integrally formed with the cylinder.

Technical Field

The present invention relates to an improvement in a buffer.

Background

Conventionally, in a shock absorber, a cylinder contains a liquid such as hydraulic oil, and when a piston moves in the cylinder, a resistance is applied to the flow of the liquid by a damping element, and a damping force due to the resistance is exerted.

The damper element is configured to include, for example, an orifice and a leaf valve provided in parallel with the orifice. Further, in the case where the piston speed is in the low speed range and the differential pressure between the upstream side and the downstream side of the damping element is smaller than the valve opening pressure of the leaf valve, the liquid flows only through the orifice. On the other hand, when the piston speed is in the medium-high speed range and the differential pressure is equal to or higher than the valve opening pressure of the leaf valve, the liquid flows through the leaf valve.

Therefore, the characteristic of the damping force with respect to the piston speed of the shock absorber (hereinafter referred to as "damping force characteristic") is limited to the opening leaf valve, and changes from the orifice characteristic proportional to the square of the piston speed specific to the orifice to the valve characteristic proportional to the piston speed specific to the leaf valve.

Further, in the shock absorber, for the purpose of adjusting the generated damping force, a bypass passage that bypasses the damping element, a needle valve that adjusts the opening area of the bypass passage, or a pilot valve that controls the back pressure of a leaf valve constituting the damping element are provided (for example, patent documents 1 and 2).

Documents of the prior art

Patent document

Patent document 1: JP2010-7758A

Patent document 2: JP2014-156885A

Summary of The Invention

Problems to be solved by the invention

For example, in the shock absorber provided with the needle valve described in JP2010-7758A, when the needle valve is driven to increase the opening area of the bypass passage, the flow rate of the liquid flowing through the damping element becomes small, and the generated damping force becomes small (soft mode in fig. 6). In contrast, when the opening area of the bypass passage is reduced, the flow rate of the liquid flowing through the damping element increases, and the generated damping force becomes large (hard mode in fig. 6).

The adjustment of the damping force by the needle valve is mainly used for adjusting the magnitude of the damping force when the piston speed is in a low speed range. Further, when the opening area of the bypass passage is adjusted by the needle valve, the magnitude of the damping force in the medium-high speed range of the piston speed can be adjusted more or less, but it is difficult to increase the adjustment range.

On the other hand, in the shock absorber including the pilot valve described in JP2014-156885a, when the valve opening pressure of the pilot valve is reduced and the back pressure of the leaf valve is reduced, the valve opening pressure of the leaf valve is reduced and the generated damping force is reduced (soft mode in fig. 7). In contrast, when the valve opening pressure of the pilot valve is increased and the back pressure of the leaf valve is increased, the valve opening pressure of the leaf valve becomes large and the generated damping force becomes large (hard mode in fig. 7).

In this way, when the back pressure of the leaf valve is controlled and the valve opening pressure is changed, the adjustment range of the damping force when the piston speed is in the medium-high speed range can be increased. However, in this case, since the characteristic curve indicating the damping force characteristic in the medium-high speed range moves up and down without changing the slope thereof, the slope of the characteristic curve changes abruptly particularly in the hard mode when the low speed range is switched to the medium-high speed range. Therefore, when the shock absorber is mounted on the vehicle, the occupant may feel uncomfortable and ride comfort may be deteriorated.

Therefore, in order to solve these problems, an object of the present invention is to provide a shock absorber capable of increasing the adjustment width of the damping force when the piston speed is in the medium-high speed range and improving the riding comfort when mounted on a vehicle.

Means for solving the problems

The buffer for solving the problem comprises: a hard-side damping element that applies resistance to a flow of liquid moving between an extension-side chamber and a compression-side chamber partitioned by a piston movably inserted in a cylinder; a solenoid valve capable of changing an opening area of a bypass passage that bypasses the hard side damping element and communicates with the expansion side chamber and the compression side chamber; a soft side damping element provided on the bypass passage in series with the solenoid valve; and a liquid storage tank connected to the compression-side chamber and pressurizing the inside of the cylinder. The hard side damping element is configured to have an orifice and a leaf valve disposed in parallel with the orifice, and the soft side damping element is configured to have a large-diameter orifice having an opening area larger than that of the orifice.

According to the above configuration, when the piston speed is in the low speed range, the characteristic of the damping force generated by the shock absorber is the orifice characteristic specific to the orifice, and when the piston speed is in the medium-high speed range, the characteristic is the valve characteristic specific to the leaf valve. Further, if the opening area of the bypass passage is changed by the solenoid valve, the distribution ratio of the flow rate flowing through each of the hard side damping element and the soft side damping element in the liquid moving between the expansion side chamber and the compression side chamber changes, so it is possible to freely set both the damping coefficient when the piston speed is in the low speed range and the damping coefficient when the piston speed is in the medium-high speed range, and it is possible to increase the adjustment range of the generated damping force.

Further, in the soft mode in which the distribution ratio of the liquid flowing through the soft-side damping element is increased, both the damping coefficient when the piston speed is in the low speed range and the damping coefficient when the piston speed is in the medium-high speed range can be reduced. In contrast, in the hard mode in which the distribution ratio of the liquid flowing through the soft-side damping element is reduced, both the damping coefficient when the piston speed is in the low speed range and the damping coefficient when the piston speed is in the medium-high speed range can be increased. Accordingly, when the damping force characteristic changes from the orifice characteristic in the low speed range to the valve characteristic in the medium-high speed range, the change in the slope of the characteristic curve is gentle in any mode, and therefore, when the shock absorber according to the present invention is mounted on a vehicle, it is possible to maintain good ride comfort in the vehicle.

In the shock absorber, the soft-side damping element may be configured to have a leaf valve provided in parallel with the large-diameter orifice. Thus, even if a leaf valve having a high valve rigidity is used as the hard-side damping element, the damping force in the soft mode is not excessively large. Therefore, the adjustment width of the damping force when the piston speed is in the medium-high speed range can be further increased.

In the damper, the solenoid valve may be set so that the opening degree thereof changes in proportion to the amount of current supplied. In this way, the opening area of the bypass passage can be adjusted steplessly.

In the damper, the solenoid valve may include: a cylindrical holder formed with a port connected to the bypass passage; a valve core which can be inserted into the bracket in a reciprocating way and can open and close the port; an urging spring that urges the valve body in one direction of movement of the valve body; and a solenoid that applies a thrust force to the valve body in a direction opposite to the biasing force of the biasing spring. Thus, the opening degree of the solenoid valve can be easily increased without increasing the stroke amount of the spool as the solenoid valve body, and therefore the adjustment width of the opening area of the bypass passage can be easily increased. Further, the degree of freedom in setting the relationship between the opening degree of the solenoid valve and the amount of energization can be increased.

In the shock absorber, the leaf valve as the hard side damping element may be provided with: an extension-side hard valve that applies resistance to the flow of liquid from the extension-side chamber to the compression-side chamber; and a compression-side hard leaf valve that applies resistance to the flow of liquid flowing from the compression-side chamber to the expansion-side chamber; meanwhile, as the leaf valve of the soft side damping element, there may be provided: an extension-side soft leaf valve that applies resistance to a flow of liquid flowing from the extension-side chamber to the compression-side chamber in the bypass passage; and a compression-side soft leaf valve that applies resistance to the flow of liquid flowing from the compression-side chamber to the expansion-side chamber in the bypass passage. In this way, the adjustment width of the damping force on both the expansion side and the compression side when the piston speed is in the medium-high speed range can be increased.

In the shock absorber, the leaf valve as the hard side damping element may be provided with: an extension-side hard leaf valve that applies resistance to the flow of liquid from the extension-side chamber to the compression-side chamber; and a compression-side hard leaf valve that applies resistance to the flow of liquid flowing from the compression-side chamber to the expansion-side chamber; meanwhile, as the leaf valve of the soft side damping element, only: and an extension-side soft leaf valve that applies resistance to the flow of liquid that flows from the extension-side chamber to the compression-side chamber in the bypass passage. In this way, the adjustment width of the damping force on the extension side when the piston speed is in the medium-high speed range can be increased.

Further, in the shock absorber described above, the valve body is movable along a straight line orthogonal to a center axis passing through the center of the piston rod. Thus, when the shock absorber is mounted on the vehicle, the valve body can be prevented from vibrating in the moving direction thereof due to vibration during traveling of the vehicle.

Further, in the shock absorber, a housing for accommodating the solenoid valve and the soft-side damping element may be provided inside, and the housing may be integrally formed with the cylinder. Thus, since it is not necessary to connect the housing and the cylinder with a hose, it is possible to prevent an unexpected damping force from being generated due to a resistance when the liquid flows through the hose. Further, since the hose can be omitted, the cost can be reduced.

Effects of the invention

According to the shock absorber of the present invention, the adjustment width of the damping force when the piston speed is in the medium-high speed range can be increased, and the riding comfort when the shock absorber is mounted on a vehicle can be improved.

Drawings

Fig. 1 is a partially cut-away front view illustrating a shock absorber according to an embodiment of the present invention.

Fig. 2 is a partially enlarged vertical cross-sectional view showing a damping force adjustment portion of a shock absorber according to an embodiment of the present invention in an enlarged manner.

Fig. 3 is a hydraulic circuit diagram of a shock absorber according to an embodiment of the present invention.

Fig. 4 is a damping force characteristic diagram showing characteristics of a damping force with respect to a piston speed of the shock absorber according to the embodiment of the present invention.

Fig. 5 is a hydraulic circuit diagram showing a modification of the shock absorber according to the embodiment of the present invention.

Fig. 6 is a damping force characteristic diagram showing a characteristic of a damping force with respect to a piston speed of a conventional shock absorber including a needle valve.

Fig. 7 is a damping force characteristic diagram showing a characteristic of a damping force with respect to a piston speed of a conventional shock absorber including a pilot valve.

Detailed Description

Hereinafter, a buffer according to an embodiment of the present invention will be described with reference to the drawings. The same reference numbers will be used throughout the drawings to refer to the same or corresponding parts. Further, the shock absorber according to the embodiment of the present invention is used for a rear shock absorber that suspends a rear wheel of a straddle-type vehicle. In the following description, the up and down in the state where the bumper is mounted on the vehicle is simply referred to as "up" and "down" unless otherwise specified.

As shown in fig. 1, a buffer a according to an embodiment of the present invention includes: a telescopic shock absorber body D having a housing 10 and a piston rod 3 which enters and exits the housing 10; a suspension spring S provided on an outer periphery of the damper main body D; a damping force adjustment unit E provided integrally with the shock absorber main body D; and a liquid storage tank T which is connected with the damping force adjusting part E through a hose.

Further, the damper a is of an inverted type, and the piston rod 3 protrudes downward from the housing 10. An axle bracket 30 is provided at the lower end of the piston rod 3. The bracket 30 is connected to a swing arm swingably connected to the vehicle body. Since the rear wheel is rotatably supported by the swing arm, the piston rod 3 can be said to be connected to the axle of the rear wheel.

On the other hand, a top cylindrical end cap 11 is screwed to the outer periphery of the upper end of the housing 10. A vehicle body side bracket 12 is provided on the top of the end cover 11, and the housing 10 is connected to the vehicle body via the bracket 12.

Thus, the damper body D is interposed between the vehicle body and the rear wheel axle. Also, when the vehicle runs on an uneven road surface or the like and the rear wheels vibrate up and down with respect to the vehicle body, the piston rod 3 enters and exits the housing 10, and the shock absorber body D expands and contracts. Thus, the expansion and contraction of the damper main body D is also referred to as expansion and contraction of the damper a.

In the present embodiment, the suspension spring S is a coil spring. The upper end of the suspension spring S is supported by an upper spring bracket 13 mounted on the outer circumference of the housing 10. On the other hand, the lower end of the suspension spring S is supported by a lower spring bracket 31 mounted on the axle-side bracket 30. Since the axle-side bracket 30 is coupled to the piston rod 3, it can be said that one end of the suspension spring S is supported by the housing 10 and the other end is supported by the piston rod 3.

When the shock absorber a contracts and the piston rod 3 enters the housing 10, the suspension spring S is compressed and exerts an elastic force to urge the shock absorber a in the extending direction. Thus, the suspension spring S exerts an elastic force according to the amount of compression, and elastically supports the vehicle body.

The direction in which the bumper a is attached is not limited to the illustrated direction, and may be, for example, a direction in which the upper and lower sides in fig. 1 are reversed. The object to which the shock absorber a is attached is not limited to the vehicle, and may be changed as appropriate. Further, the suspension spring S may be a spring other than a coil spring, such as an air spring, and the suspension spring S may be omitted depending on the mounting object of the shock absorber a.

Next, the damper main body D is of a multi-cylinder type, and a cylinder 1 as an inner cylinder is provided inside the housing 10. A piston 2 is slidably inserted into the cylinder 1. The piston 2 is connected to the upper end outer periphery of the piston rod 3 by a nut 32. Further, when the shock absorber a expands and contracts, the piston rod 3 moves in and out of the cylinder 1, and the piston 2 moves up and down (axially) in the cylinder 1.

As described above, the top cylindrical end cap 11 is screwed to the outer periphery of the upper end of the housing 10, and the upper end of the housing 10 is closed by the end cap 11. On the other hand, an annular rod guide 14 that slidably supports the piston rod 3 is attached to the lower end of the housing 10. Seals 15, 16, 17 are mounted on the rod guide 14, and seal the outer periphery of the piston rod 3 and the inner periphery of the housing 10, respectively.

In this way, the inside of the housing 10 is a sealed space, and the liquid contained in the housing 10 including the cylinder 1 is prevented from leaking to the outside. A working chamber L filled with a liquid such as hydraulic oil is formed in the cylinder 1, and the working chamber L is partitioned by the piston 2 into a lower extension side chamber L1 and an upper compression side chamber L2.

The extension-side chamber L1 is a chamber that is compressed by the piston 2 when the shock absorber a extends, of two chambers partitioned by the piston 2. On the other hand, the compression side chamber L2 is a chamber compressed by the piston 2 when the shock absorber a is compressed, of the two chambers divided by the piston 2.

The piston 2 is provided with an extension-side passage 2a and a compression-side passage 2b for communicating the extension-side chamber L1 and the compression-side chamber L2, and a hard-side damping element FH that applies resistance to the flow of liquid that moves between the extension-side chamber L1 and the compression-side chamber L2 after flowing through the extension-side passage 2a or the compression-side passage 2b is attached. The hard side damping element FH includes: an extension-side hard leaf valve 20 that is a leaf valve for opening and closing the extension-side passage 2 a; a compression-side hard leaf valve 21 for opening and closing the compression-side passage 2 b; and an orifice 22 (fig. 3).

The hard leaf valve on the expansion side and the hard leaf valve on the compression side 20 are each a thin annular plate made of metal or the like, or a laminated body in which these annular plates are laminated, and have elasticity. The extension-side hard leaf valve 20 is attached to the upper side of the piston 2 in a state where the outer peripheral side thereof is allowed to bend, and the pressure of the extension-side chamber L1 acts on the extension-side hard leaf valve 20 in a direction in which the outer peripheral portion bends upward. The compression-side hard leaf valve 21 is stacked on the lower side of the piston 2 in a state where the outer peripheral side thereof is allowed to bend, and the pressure of the compression-side chamber L2 acts on the compression-side hard leaf valve 21 in a direction in which the outer peripheral portion bends downward.

The orifice 22 is formed by a notch provided in the outer peripheral portion of one or both of the expansion-side hard leaf valve and the compression-side hard leaf valve 20 and 21 which are unseated or seated on the valve seat of the piston 2, or by an imprint provided on the valve seat. Therefore, the orifice 22 can be said to be provided in parallel with the hard leaf valves on the expansion side and the hard leaf valves on the compression side 20 and 21 in one or both of the expansion side port 2a and the compression side port 2 b.

The expansion-side chamber L1 is compressed by the piston 2 when the shock absorber a expands, and its internal pressure rises and is higher than the pressure of the compression-side chamber L2. On the other hand, the compression side chamber L2 is compressed by the piston 2 when the shock absorber a contracts, and the internal pressure thereof rises and becomes higher than the pressure of the extension side chamber L1. Thus, when the shock absorber a expands and contracts, a differential pressure is generated between the expansion side chamber L1 and the compression side chamber L2. When the shock absorber a expands and contracts, the piston speed is in the low speed range and the differential pressure is smaller than the valve opening pressures of the expansion-side and compression-side hard leaf valves 20 and 21, the liquid flows through the orifice 22 and then flows from the expansion-side chamber L1 to the compression-side chamber L2 during expansion and flows from the compression-side chamber L2 to the expansion-side chamber L1 during contraction. Then, resistance is applied to the flow of the liquid through the orifice 22.

When the piston speed increases and falls within the medium-high speed range when the shock absorber a expands, and the differential pressure increases and becomes equal to or higher than the valve opening pressure of the expansion-side hard leaf valve 20, the outer peripheral portion of the expansion-side hard leaf valve 20 bends upward to form a gap between the outer peripheral portion and the piston 2, and the liquid flows through the gap, flows from the expansion-side chamber L1 to the compression-side chamber L2, and exerts resistance against the flow of the liquid.

When the piston speed increases and falls within the medium-high speed range when the shock absorber a contracts, and the differential pressure increases and becomes equal to or higher than the valve opening pressure of the compression-side hard leaf valve 21, the outer peripheral portion of the compression-side hard leaf valve 21 bends downward to form a gap between the outer peripheral portion and the piston 2, and the liquid flows through the gap, flows from the compression-side chamber L2 to the extension-side chamber L1, and exerts resistance against the flow of the liquid.

As is apparent from the above, the orifice 22 of the hard side damping element FH and the expansion side hard leaf valve 20 function as the expansion side first damping element which applies resistance to the flow of the liquid flowing from the expansion side chamber L1 to the compression side chamber L2 when the shock absorber a expands. Further, the orifice 22 of the hard side damper element FH and the compression side hard leaf valve 21 function as the compression side first damper element, which applies resistance to the flow of the liquid flowing from the compression side chamber L2 to the extension side chamber L1 when the shock absorber a contracts. The resistance of the first damping elements is caused by the orifice 22 when the piston speed is in the low speed range, and is caused by the expansion-side hard leaf valves or the compression-side hard leaf valves 20 and 21 when the piston speed is in the medium-high speed range.

Next, a cylindrical clearance C1 is formed between the cylinder 1 and the housing 10. The clearance C1 is always in communication with the extension-side chamber L1 via a hole 1a formed in the lower end portion of the cylinder 1. Further, the gap C1 communicates with the damping force adjustment portion E through a hole 10a formed in the upper end portion of the housing 10 and an extension side opening 11a formed in the end cover 11. Further, a compression-side opening 11b is formed in the end cover 11, and the compression-side chamber L2 communicates with the damping-force adjustment portion E through the compression-side opening 11 b.

As shown in fig. 2, the damping force adjustment portion E includes: a cylindrical case 4; a cover 40 for closing one end of the housing 4; a bottom member 41 for closing the other end of the housing 4; a valve housing 5 for being held on the bottom part 41 and fixed in the housing 4; and an electromagnetic valve V provided on the cover 40 side of the valve housing 5 in the housing 4.

In the present embodiment, the center axis Y of the damping force adjustment portion E passing through the center of the housing 4 is disposed along a straight line Z orthogonal to the center axis X of the shock absorber body D passing through the center of the piston rod 3 shown in fig. 1. Hereinafter, for convenience of explanation, the left and right sides of the damping force adjuster E in fig. 2 are simply referred to as "left" and "right", but the direction in which the damping force adjuster E is attached may be changed as appropriate. For example, the damping force adjustment portion E may be disposed such that the center axis Y extends in the vehicle width (left-right) direction, or may be disposed such that it extends in the front-rear direction.

In the present embodiment, the case 4 of the damping force adjustment portion E is integrally formed with the end cap 11 for closing the upper end of the housing 10 and the bracket 12 on the vehicle body side. The integral molding herein means that a plurality of members are integrally molded by being joined together at the same time as molding, and does not mean that a plurality of members molded separately are bonded or joined together.

Next, as shown in fig. 2, the housing 4 includes: an auxiliary cylinder portion 4a for accommodating the valve housing 5 therein; and a housing portion 4b for accommodating the solenoid valve V. The interior of the auxiliary cylinder portion 4a is partitioned into a first chamber L3 on the left side (the lid 40 side) and a second chamber L4 on the right side (the opposite lid side) by the valve housing 5. The valve housing 5 is provided with an extension-side soft channel 5a and a compression-side soft channel 5b for communicating the first chamber L3 and the second chamber L4, and a soft-side damper element FS that applies resistance to the flow of liquid that moves between the first chamber L3 and the second chamber L4 after passing through the extension-side soft channel 5a or the compression-side soft channel 5b is attached.

Further, a gap C2 is formed between the housing portion 4b and the solenoid valve V, and a solenoid valve V switch is used for connecting the gap C2 and a portion of the first chamber L3. Further, a through hole (not shown) that opens in the gap C2 and communicates with the extension-side opening 11a is formed in the housing portion 4 b. As described above, the extension side opening 11a communicates with the extension side chamber L1 via the clearance C1 between the cylinder 1 and the housing 10.

On the other hand, a through hole (not shown) is formed in the right side of the valve housing 5 of the auxiliary cylinder portion 4a, and the through hole communicates with the compression-side opening 11b (fig. 1). As described above, the compression-side opening 11b communicates with the compression-side chamber L2, and the second chamber L4 always communicates with the compression-side chamber L2. Further, a tank T is connected to the second chamber L4, so that the compression-side chamber L2 is always in communication with the tank T.

As shown in fig. 1, the reservoir tank T is partitioned into a liquid chamber L5 and a gas chamber G by the free piston 18. The gas chamber G is filled with high-pressure gas, and the liquid chamber L5 is pressurized by the pressure of the gas chamber G, which acts on the inside of the cylinder 1. The pressure in the compression-side chamber L2 is always substantially the same as the pressure in the tank T (tank pressure).

That is, in the present embodiment, the cylindrical clearance C1 formed between the cylinder 1 and the housing 10, the clearance C2 in the housing portion 4B, the first chamber L3, and the second chamber L4 are provided, and the bypass passage B for communicating the extension-side chamber L1 and the compression-side chamber L2 is formed so as to bypass the hard-side damping element FH. The reservoir tank T is connected to the bypass passage B, and the solenoid valve V and the soft-side damper element FS are provided in the bypass passage B in series with the extension-side chamber L1 side of the connection portion of the reservoir tank T. The soft side damping element FS is configured to include: an extension-side soft leaf valve 50 for opening and closing the extension-side soft channel 5 a; a compression-side soft leaf valve 51 for opening and closing the compression-side soft channel 5 b; and an orifice 52 (fig. 3).

The expansion-side and compression-side soft leaf valves 50 and 51 are each a thin annular plate made of metal or the like, or a laminate in which these annular plates are laminated, and have elasticity. The extension-side soft leaf valve 50 is attached to the right side of the valve housing 5 in a state where the outer peripheral side thereof is allowed to flex, and the pressure of the first chamber L3 acts on the extension-side soft leaf valve 50 in a direction in which the outer peripheral portion flexes to the right side. The compression-side soft leaf valve 51 is laminated on the left side of the valve housing 5 in a state where the outer peripheral side thereof is allowed to bend, and the pressure of the second chamber L4 acts on the compression-side soft leaf valve 51 in a direction in which the outer peripheral portion bends to the left.

The orifice 52 is formed by notches provided in the outer peripheral portions of the expansion-side and compression-side soft leaf valves 50 and 51 that are unseated or seated on the valve seat of the valve housing 5, or by markings provided on the valve seat. Therefore, the orifice 52 can be said to be provided in parallel with the expansion-side and compression-side soft leaf valves 50 and 51 in one or both of the expansion-side soft passage 5a and the compression-side soft passage 5 b.

When the shock absorber a extends and when the solenoid valve V is opened, the pressure of the first chamber L3 rises after receiving the pressure of the extension side chamber L1, and is higher than the pressure of the second chamber L4. On the other hand, when the shock absorber a contracts and when the solenoid valve V opens, the pressure of the second chamber L4 rises after receiving the pressure of the compression-side chamber L2 (reservoir pressure), and is higher than the pressure of the first chamber L3. As the shock absorber a expands and contracts, when the solenoid valve V is opened, a differential pressure is generated between the first chamber L3 and the second chamber L4.

When the shock absorber a expands and contracts and the electromagnetic valve V is opened, the piston speed is in the low speed range and the differential pressure is smaller than the valve opening pressures of the expansion-side and compression-side soft leaf valves 50 and 51, the liquid flows through the orifice 52, flows from the first chamber L3 to the second chamber L4 during expansion, that is, from the expansion-side chamber L1 to the compression-side chamber L2, and flows from the second chamber L4 to the first chamber L3 during contraction, that is, from the compression-side chamber L2 to the expansion-side chamber L1, and resistance is applied to the flow of the liquid.

When the shock absorber a extends and the electromagnetic valve V is opened, the piston speed increases and falls within the medium-high speed range, and when the differential pressure increases and becomes equal to or higher than the valve opening pressure of the extension-side soft leaf valve 50, the outer peripheral portion of the extension-side soft leaf valve 50 bends to form a gap between the outer peripheral portion thereof and the valve housing 5, and the liquid flows through the gap from the first chamber L3 to the second chamber L4, that is, from the extension-side chamber L1 to the compression-side chamber L2, and resistance is applied to the flow of the liquid.

When the shock absorber contracts and the electromagnetic valve V opens, the piston speed increases and falls within the medium-high speed range, and when the differential pressure increases and becomes equal to or higher than the valve opening pressure of the compression-side soft leaf valve 51, the outer peripheral portion of the compression-side soft leaf valve 51 bends to form a gap between the outer peripheral portion thereof and the valve housing 5, and the liquid flows through the gap from the second chamber L4 to the first chamber L3, that is, from the compression-side chamber L2 to the extension-side chamber L1, and resistance is applied to the flow of the liquid.

As is clear from the above, the orifice 52 of the soft side damping element FS and the expansion side soft leaf valve 50 function as the expansion side second damping element that applies resistance to the flow of the liquid flowing from the expansion side chamber L1 to the compression side chamber L2 in the bypass passage B when the shock absorber a expands. The orifice 52 of the soft side damper element FS and the compression side soft leaf valve 51 function as a compression side second damper element that applies resistance to the flow of liquid flowing from the compression side chamber L2 to the extension side chamber L1 in the bypass passage B when the shock absorber a contracts. The resistance of the first and second damping elements is caused by the orifice 52 when the piston speed is in the low speed range, and by the expansion-side soft leaf valves or the compression-side soft leaf valves 50 and 51 when the piston speed is in the medium-high speed range.

The extension-side soft leaf valve 50 of the soft-side damper element FS is a valve having a lower valve rigidity (is more flexible) than the extension-side hard leaf valve 20 of the hard-side damper element FH, and has a smaller resistance (pressure loss) to the flow of the liquid when the flow rate is the same. Similarly, the compression-side soft leaf valve 51 of the soft-side damper element FS has a lower valve rigidity (is more flexible) than the compression-side hard leaf valve 21 of the hard-side damper element FH, and has a smaller resistance (pressure loss) to the flow of the liquid at the same flow rate. In other words, under the same conditions, the liquid flows more easily through the soft leaf valves 50 and 51 than through the hard leaf valves 20 and 21. Further, the orifice 52 of the soft side damping element FS is a large diameter orifice having a larger opening area than the orifice 22 of the hard side damping element FH, and the resistance (pressure loss) to the flow of the liquid is small when the flow rate is the same.

Next, the electromagnetic valve V is configured to have: a cylindrical holder 6 fixed in the housing 4; a valve core 7 reciprocatably inserted into the holder 6; an urging spring 8 that urges the valve body 7 in one of the moving directions; and a solenoid 9 that applies a thrust force to the valve body 7 in a direction opposite to the biasing force of the biasing spring 8. Then, the opening degree of the solenoid valve V is adjusted by changing the position of the valve body 7 in the holder 6.

More specifically, the bracket 6 is disposed along the center axis Y of the housing 4 with one end in the axial direction facing the left side (the cap 40 side) and the other end facing the right side (the valve housing 5 side) in the housing 4. Further, the holder 6 is formed with one or more ports 6a penetrating the wall thickness thereof in the radial direction. The port 6a communicates with the extension-side chamber L1 through a clearance C2, and is opened and closed by the valve body 7.

The valve body 7 is cylindrical and is slidably inserted into the holder 6. A plate 70 is laminated on the left end of the valve body 7, and a plunger 9a of the solenoid 9, which will be described later, abuts against the plate 70. On the other hand, the biasing spring 8 abuts on the right end of the valve body 7, and the valve body 7 is biased to the left side (solenoid 9 side) by the biasing spring 8.

Further, the center hole 7a formed in the center portion of the spool 7 communicates with the first chamber L3 via the right end opening of the spool 7. Further, an annular groove 7b is formed in the valve body 7 along the circumferential direction of the outer periphery thereof, and one or more side holes 7c for communicating the inside of the annular groove 7b with the center hole 7a are formed. Thereby, the inside of the annular groove 7b communicates with the first chamber L3 via the side hole 7c and the center hole 7 a.

According to the above configuration, in the case where the valve body 7 is present at the position where the annular groove 7b opposes the port 6a of the carrier 6, the communication of the extension side chamber L1 and the first chamber L3 is permitted. The state where the annular groove 7B faces the port 6a is a state where the annular groove 7B overlaps the port 6a when viewed in the radial direction, and the opening area of the bypass passage B changes depending on the amount of overlap.

For example, when the amount of overlap between the annular groove 7B and the port 6a increases and the opening degree of the solenoid valve V increases, the opening area of the bypass passage B increases. Conversely, when the amount of overlap between the annular groove 7B and the port 6a decreases and the opening degree of the solenoid valve V decreases, the opening area of the bypass passage B decreases. Further, when the spool 7 moves to a position where the annular groove 7B does not completely overlap with the port 6a and closes the electromagnetic valve V, the communication of the bypass passage B is shut off.

Although not shown in detail, the solenoid 9 of the electromagnetic valve V includes: a cylindrical stator including a coil; a cylindrical movable core inserted into the stator so as to be movable; and a plunger 9a attached to the inner periphery of the movable core and having a tip abutting against the plate 70. A wire harness 90 for supplying power to the solenoid 9 protrudes outward from the cover 40 and is connected to a power source.

When the solenoid 9 is energized by the wire harness 90, the movable core is pulled toward the right side, the plunger 9a moves rightward, and the valve body 7 moves rightward against the biasing force of the biasing spring 8. Then, the annular groove 7b is opposed to the port 6a, and the solenoid valve V is opened. The relationship between the opening degree of the solenoid valve V and the energization amount of the solenoid 9 is a proportional relationship having a positive proportional constant, and the opening degree is larger as the energization amount is larger. Further, when the energization to the solenoid 9 is cut off, the electromagnetic valve V is closed.

In this way, the electromagnetic valve V of the present embodiment is of a normally closed type, and the valve element 7 as the valve body is biased in the closing direction by the biasing spring 8, and the valve element 7 is biased in the opening direction by the solenoid 9. Further, the opening degree increases in proportion to the amount of energization of the solenoid valve V, and the opening area of the bypass passage B becomes larger as the opening degree increases. Therefore, it can be said that the opening area of the bypass passage B increases in proportion to the amount of energization of the solenoid valve V.

As described above, as shown in fig. 3, the buffer a according to the present embodiment includes: a cylinder 1; a piston 2 movably inserted into the cylinder 1 and dividing the interior of the cylinder 1 into an extension-side chamber L1 and a compression-side chamber L2; a piston rod 3 having a front end connected to the piston 2 and a rear end protruding outward of the cylinder 1; and a liquid storage tank T connected to the compression-side chamber L2 in the cylinder 1; the pressure in the compression-side chamber L2 is the tank pressure. Further, in the shock absorber a, as passages for communicating the extension side chamber L1 and the compression side chamber L2, an extension side passage 2a, a compression side passage 2B, and a bypass passage B are provided.

Further, an expansion-side hard leaf valve 20 and a compression-side hard leaf valve 21 for opening and closing these passages are provided in the expansion-side passage 2a and the compression-side passage 2b, respectively, and an orifice 22 is provided in one or both of the expansion-side passage 2a and the compression-side passage 2b, and is provided in parallel with the expansion-side hard leaf valve and the compression-side hard leaf valve 20, 21. The hard side damping element FH is configured to have the expansion side hard leaf valve 20, the compression side hard leaf valve 21, and the orifice 22, and to apply resistance to the flow of the liquid.

On the other hand, the reservoir T is connected to the bypass passage B, and the extension-side soft passage 5a and the compression-side soft passage 5B branch off from the extension-side chamber L1 side of the connection portion with the reservoir T in the bypass passage B. Further, the extension-side soft leaf valve 50 and the compression-side soft leaf valve 51 for opening and closing the extension-side soft channel 5a and the compression-side soft channel 5b are provided, respectively, and an orifice 52 is provided in one or both of the extension-side soft channel 5a and the compression-side soft channel 5b in parallel with the extension-side soft leaf valve and the compression-side soft leaf valve 50, 51.

The orifice 52 is a large-diameter orifice having a larger opening area than the orifice 22. The soft leaf valves 50 and 51 are leaf valves having a valve rigidity lower than that of the hard leaf valves 20 and 21. The soft-side damping element FS is configured to have an expansion-side soft leaf valve 50, a compression-side soft leaf valve 51, and an orifice 52, and to reduce resistance applied to the flow of the liquid.

Further, a solenoid valve V is provided in the bypass passage B on the extension side chamber L1 side of the connection portion of the reservoir T in series with the soft side damping element FS, and the opening area of the bypass passage B can be changed by adjusting the amount of current supplied to the solenoid valve V. The solenoid valve V is of a normally closed type, and is set to increase the opening area of the bypass passage B in proportion to the amount of energization.

Next, an operation of the buffer a according to an embodiment of the present invention will be described.

When the shock absorber a extends, the piston rod 3 is retracted from the cylinder 1, and the piston 2 compresses the extension-side chamber L1. Then, while the liquid in the extension side chamber L1 moves to the compression side chamber L2 through the hard side damping element FH or the soft side damping element FS of the bypass passage B, the volumetric amount of the liquid of the piston rod 3 withdrawn from the cylinder 1 is supplied from the reservoir T to the compression side chamber L2. The hard side damper element FH or the soft side damper element FS exerts a resistance on the flow of the liquid flowing from the extension side chamber L1 to the compression side chamber L2, and generates an extension side damping force due to the resistance. When the shock absorber a extends, the distribution ratio of the liquid flowing through the hard side damping elements FH and the soft side damping elements FS changes according to the amount of current supplied to the solenoid valve V.

Specifically, when the shock absorber a extends, the liquid flows through the extension-side hard leaf valve 20 or the orifice 22 which constitutes the first damping element on the extension side of the hard-side damping element FH, or the extension-side soft leaf valve 50 or the orifice 52 which constitutes the second damping element on the extension side of the soft-side damping element FS. In this way, the first damper element and the second damper element on the expansion side are configured to have the orifices 22 and 52, respectively, and the hard leaf valve 20 or the soft leaf valve 50 as leaf valves arranged in parallel therewith. Therefore, when the piston speed is in the low speed range, the damping force characteristic on the extension side is an orifice characteristic proportional to the square of the piston speed specific to the orifice; when the piston speed is in the medium-high speed range, it is a valve characteristic proportional to the piston speed specific to the leaf valve.

When the amount of current supplied to the solenoid valve V is increased to increase the opening degree, the flow rate of the bypass passage B increases, the proportion of the liquid flowing through the extension-side damping element of the soft-side damping element FS increases, and the proportion of the liquid flowing through the extension-side damping element of the hard-side damping element FH decreases. Since the orifice 52, which is the expansion-side damping element of the soft-side damping element FS, is a large-diameter orifice having a larger opening area than the orifice 22, which is the expansion-side damping element of the hard-side damping element FH, the damping coefficient increases in both the low speed range and the medium-high speed range and the expansion-side damping force generated with respect to the piston speed decreases as the proportion of the liquid flowing toward the soft-side damping element FS increases. When the amount of current supplied to the solenoid valve V is maximized, the solenoid valve V is fully opened. Then, the damping coefficient becomes the minimum value, and the extension-side damping force generated with respect to the piston speed becomes the minimum value.

In contrast, when the amount of current supplied to the solenoid valve V is decreased to decrease the opening degree, the flow rate of the bypass passage B decreases, the proportion of the liquid flowing through the extension-side damping element of the soft-side damping element FS decreases, and the proportion of the liquid flowing through the extension-side damping element of the hard-side damping element FH increases. Then, the damping coefficient increases in both the low speed range and the middle and high speed range, and the extension-side damping force generated with respect to the piston speed increases. When the energization of the solenoid valve V is cut off, the solenoid valve V is closed, and the entire flow rate flows through the extension side damping element of the hard side damping element FH. Then, the damping coefficient becomes maximum, and the extension-side damping force generated with respect to the piston speed becomes maximum.

As described above, when the distribution ratio of the liquid flowing through the first damper element and the second damper element on the expansion side of the hard side damper element FH and the soft side damper element FS is changed by the solenoid valve V, the damping coefficient changes in magnitude, and as shown in fig. 4, the slope of the characteristic curve indicating the damping force characteristic on the expansion side changes. The extension-side damping force is adjusted between a hard mode in which the generated damping force is increased while the gradient of the characteristic curve is maximized and a soft mode in which the generated damping force is decreased while the gradient is minimized.

In the soft mode, the slope of the characteristic curve representing the damping force characteristic decreases in both the low speed range and the middle and high speed range, and in the hard mode, the slope of the characteristic curve representing the damping force characteristic increases in both the low speed range and the middle and high speed range. Therefore, in any mode, the change in the damping force characteristic from the orifice characteristic to the valve characteristic is gentle.

Further, the expansion-side damping element of the soft-side damping element FS includes a soft leaf valve 50 that is a leaf valve having low valve rigidity and is arranged in parallel with the orifice 52. Therefore, as a leaf valve constituting the expansion-side damping element of the hard-side damping element FH, a hard leaf valve having high valve rigidity and high valve opening pressure is used, and the damping force in the soft mode is not excessively large even if the adjustment width of the direction for increasing the expansion-side damping force is increased.

In contrast, when the shock absorber a contracts, the piston rod 3 enters the cylinder 1, and the piston 2 compresses the compression-side chamber L2. Then, while the liquid in the compression side chamber L2 moves to the extension side chamber L1 by passing through the hard side damping element FH or the soft side damping element FS of the bypass passage B, the volumetric amount of the liquid entering the piston rod 3 of the cylinder 1 is discharged from the compression side chamber L2 to the reservoir T. The hard side damper element FH or the soft side damper element FS exerts a resistance on the flow of the liquid flowing from the compression side chamber L2 to the extension side chamber L1, and generates a compression side damping force due to the resistance. When the shock absorber a contracts, the distribution ratio of the liquid flowing through the hard side damping element FH and the soft side damping element FS changes according to the amount of energization of the solenoid valve V.

Specifically, when the shock absorber a contracts, the liquid flows through the compression-side hard leaf valve 21 or the orifice 22 constituting the first damping element on the compression side of the hard-side damping element FH, or through the compression-side soft leaf valve 51 or the orifice 52 constituting the second damping element on the compression side of the soft-side damping element FS. In this way, the first and second compression-side damper elements are configured to have the orifices 22 and 52, respectively, and the hard leaf valve 21 or the soft leaf valve 51 as leaf valves arranged in parallel therewith. Therefore, when the piston speed is in the low speed range, the damping force characteristic on the compression side is an orifice characteristic proportional to the square of the piston speed specific to the orifice; when the piston speed is in the medium-high speed range, it is a valve characteristic proportional to the piston speed specific to the leaf valve.

When the distribution ratio of the liquid flowing through the hard side damping elements FH and the soft side damping elements on the compression side first damping elements and the second damping elements is changed during contraction of the shock absorber a, the damping coefficient changes in magnitude, and the slope of the characteristic curve representing the damping force characteristic on the compression side changes, in the same manner as the damping force on the extension side. Further, even when the shock absorber a contracts, the compression-side damping force is adjusted between a hard mode in which the generated damping force is increased while the gradient of the characteristic curve is maximized, and a soft mode in which the generated damping force is decreased while the gradient is minimized, as in the case of the expansion.

In addition, as in the case of the expansion, even in the contraction mode, the slope of the characteristic curve indicating the damping force characteristic decreases in both the low speed range and the middle and high speed range, and increases in both the low speed range and the middle and high speed range in the hard mode, so that the change in the damping force characteristic from the orifice characteristic to the valve characteristic is gentle in either mode. Further, since the compression side damping element of the soft side damping element FS also has the soft leaf valve 51 which is a leaf valve having a low valve rigidity in parallel with the orifice 52, the damping force in the soft mode is not excessively increased even if a hard leaf valve having a high valve rigidity and a high valve opening pressure is used as the leaf valve of the compression side damping element constituting the hard side damping element FH.

Next, the operation and effect of the buffer a according to an embodiment of the present invention will be described.

The buffer a according to the present embodiment includes: a cylinder 1; a piston 2 axially movably inserted into the cylinder 1 and dividing the interior of the cylinder 1 into an extension side chamber L1 and a compression side chamber L2; a piston rod 3 connected to the piston 2 and having one end protruding outward of the cylinder 1; and a reservoir tank T connected to the compression-side chamber L2 and pressurizing the cylinder 1.

Further, the buffer a includes: a hard side damping element FH that applies resistance to the flow of the liquid moving between the extension side chamber L1 and the compression side chamber L2; a solenoid valve V that can change the opening area of a bypass passage B that bypasses the hard side damping element FH and communicates with the extension side chamber L1 and the compression side chamber L2; and a soft-side damping element FS provided on the bypass passage B in series with the electromagnetic valve V. The hard side damping element FH is configured to have an orifice 22 and expansion side and compression side hard leaf valves 20 and 21 as leaf valves provided in parallel therewith. On the other hand, the soft side damping element FS is configured to have an orifice (large diameter orifice) 52 having a larger opening area than the orifice 22.

According to the above configuration, since the inside of the cylinder 1 is pressurized by the reservoir tank T, the responsiveness of generation of the damping force can be maintained well. Further, the damping force generated when the shock absorber a expands and contracts has a characteristic of an orifice characteristic specific to the orifice when the piston speed is in the low speed range, and a valve characteristic specific to the leaf valve when the piston speed is in the medium and high speed range. Further, if the opening area of the bypass passage B is changed by the solenoid valve V, the distribution ratio of the flow rates of the liquid flowing through the hard side damping element FH and the soft side damping element FS in the liquid moving between the expansion side chamber L1 and the compression side chamber L2 during expansion and contraction of the shock absorber a changes, so that both the damping coefficient in the low speed range and the damping coefficient in the medium/high speed range of the piston speed can be freely set, and the adjustment range of the damping force in the medium/high speed range of the piston speed can be increased.

Further, in the soft mode in which the opening area of the bypass passage B is changed and the distribution ratio of the liquid flowing to the soft side damping element FS is increased, both the damping coefficient when the piston speed is in the low speed range and the damping coefficient when the piston speed is in the medium-high speed range are decreased. On the other hand, in the hard mode in which the distribution ratio of the liquid to the soft side damping element FS is reduced, both the damping coefficient when the piston speed is in the low speed range and the damping coefficient when the piston speed is in the medium-high speed range are increased. Therefore, when the damping force characteristic changes from the orifice characteristic in the low speed range to the valve characteristic in the medium and high speed range, the change in the slope of the characteristic curve is gentle in either mode. As a result, when the shock absorber a according to the present embodiment is mounted on a vehicle, the uncomfortable feeling due to the change in the inclination can be reduced, and good riding comfort in the vehicle can be maintained.

In the shock absorber a of the present embodiment, the soft side damping element is configured to include the above-described orifice (large diameter orifice) 52, and the expansion side soft leaf valve and the compression side soft leaf valve 50, 51 as leaf valves provided in parallel with the orifice 52. In this way, when the leaf valve is also provided in the soft side damping element FS, the damping force in the soft mode is not excessively large even if the hard leaf valves 20 and 21, which are the leaf valves of the hard side damping element FH, are valves having high valve rigidity and high valve opening pressure. That is, according to the above configuration, the hard leaf valves 20 and 21 can be used as leaf valves of the hard side damping elements, which are valves having high valve rigidity. In addition, in this way, since the adjustment width of the damping force is increased in the direction of increasing the damping force, the adjustment width of the damping force when the piston speed is in the medium-high speed range can be further increased.

In addition, in the present embodiment, as the leaf valve of the hard side damping element FH, there may be provided: an extension-side hard leaf valve 20 that applies resistance to the flow of liquid from the extension-side chamber L1 to the compression-side chamber L2; and a compression-side hard leaf valve 21 that applies resistance to the flow of liquid from the compression-side chamber L2 to the extension-side chamber L1. Further, as the leaf valve of the soft side damping element FS, there may be provided: an extension-side soft leaf valve 50 that applies resistance to the flow of liquid flowing from the extension-side chamber L1 to the compression-side chamber L2 in the bypass passage B; and a compression-side soft leaf valve 51 that applies resistance to the flow of liquid flowing from the compression-side chamber L2 to the extension-side chamber L1 in the bypass passage B. Accordingly, the adjustment width of the damping force is increased in the direction of increasing the damping force both at the time of extension and at the time of contraction of the shock absorber a, and therefore, the adjustment width of the damping force can be further increased on both the extension side and the compression side when the piston speed is in the middle-high speed range.

However, in the shock absorber a of the present embodiment, since the tank T is connected to the compression side chamber L2, the pressure in the compression side chamber L2 does not become equal to or higher than the tank pressure, and therefore the adjustment width of the compression side damping force cannot be made as large as the adjustment width of the extension side damping force. Therefore, as in the shock absorber a1 shown in fig. 5, the compression-side soft leaf valve 51 of the soft-side damping element FS may be eliminated, and only the orifice 52 may be provided as the compression-side damping element of the soft-side damping element FS. In other words, as the leaf valve of the soft side damping element FS, only the extension side soft leaf valve 50 may be provided, which applies resistance to the flow of the liquid flowing from the extension side chamber L1 to the compression side chamber L2 in the bypass passage B.

Further, in the accumulator T of the present embodiment, a gas chamber G for enclosing high-pressure gas is formed, and the pressure in the cylinder 1 is pressurized by the pressure in the gas chamber G. However, the structure of the reservoir tank T may be modified as appropriate. For example, in the present embodiment, the gas chamber G and the liquid chamber L5 are partitioned by the free piston 18, but an air bag, a bellows, or the like may be used instead of the free piston 18. Further, a metal spring such as a coil spring for biasing the free piston 18 toward the liquid chamber L5 may be provided in the reservoir T, and the interior of the cylinder 1 may be pressurized by the biasing force.

In the present embodiment, the opening degree of the solenoid valve V is set to vary in proportion to the amount of current supplied. With this configuration, the opening area of the bypass passage B can be changed steplessly.

In the present embodiment, the electromagnetic valve V includes: a cylindrical holder 6 formed with a port 6a connected to the bypass passage B; a spool 7 movably inserted into the holder 6 and opening and closing the port 6 a; an urging spring 8 that urges the valve body 7 in one of the movement directions of the valve body 7; and a solenoid 9 that applies a thrust force to the valve body 7 in a direction opposite to the biasing force of the biasing spring 8.

Here, for example, in the case where a needle valve capable of reciprocating is provided as a valve body as in the solenoid valve described in JP2010-7758A and the opening degree is changed by adjusting the size of the gap formed between the tip end of the needle valve and the valve seat, the stroke amount of the valve body needs to be increased in order to increase the adjustment width of the opening degree, but this may not be possible.

Specifically, when the stroke amount of the needle valve is increased, the movable space of the needle valve is increased, and it is difficult to secure the accommodation space. Further, in order to increase the stroke amount of the needle valve, when the stroke amount of the plunger of the solenoid is to be increased, the design of the solenoid needs to be changed, which is very complicated. Further, when the stroke amount of the needle valve is increased without changing the design of the solenoid, a member for increasing the movement amount of the needle valve with respect to the movement amount of the plunger is required, the number of components is increased, and it is difficult to secure the accommodation space.

In contrast, in the solenoid valve V of the present embodiment, the valve body 7 reciprocally inserted into the cylindrical holder 6 opens and closes the port 6a formed in the holder 6, thereby opening and closing the solenoid valve V. Therefore, if the plurality of ports 6a are formed in the circumferential direction of the carrier 6 or formed in a long shape in the circumferential direction, the opening degree of the electromagnetic valve V can be increased without increasing the stroke amount of the spool 7 as the valve body of the electromagnetic valve V. Therefore, the adjustment width of the opening degree of the solenoid valve V can be increased, and the adjustment width of the damping force can be easily increased.

Further, according to the above configuration, the relationship between the opening degree of the solenoid valve V and the amount of energization can be easily changed. For example, when the relationship between the opening degree of the solenoid valve V and the amount of energization is a negative proportional relationship having a negative proportional constant, and the opening degree is desired to be smaller as the amount of energization is larger, the port 6a or the annular groove 7b for opening the port 6a may be disposed at a position at which the port 6a is maximally opened when deenergized.

Further, an extension side port communicating with the extension side soft passage and a compression side port communicating with the compression side soft passage may be provided and opened or closed, respectively. In this way, the configuration of the solenoid valve V and the relationship between the opening degree and the amount of energization of the solenoid valve V can be freely changed.

Further, in the shock absorber A, A1 shown in fig. 1 and 5, the damping forces on both the expansion side and the compression side can be exerted, and the damping forces on both the expansion side and the compression side can be adjusted by the solenoid valve V. However, one of the hard leaf valves on the expansion side and the hard leaf valves on the compression side 20 and 21 of the hard side damping element FH and one or both of the soft leaf valves on the expansion side and the soft leaf valves on the compression side 50 and 51 of the soft side damping element FS may be omitted, the shock absorber A, A1 may be a one-way shock absorber that exerts a damping force only in either of the expansion and contraction states, or the damping force on either of the expansion side and the compression side may be adjusted only by an electromagnetic valve.

In the present embodiment, the valve body 7 moves along the center axis Y of the bottomed cylindrical case 4. The center axis Y of the housing 4 is arranged along a straight line Z (fig. 1) orthogonal to the center axis X passing through the center of the piston rod 3, and therefore the valve element 7 can be said to move along the straight line Z.

According to the above configuration, the valve body 7 moves in the direction orthogonal to the expansion and contraction direction of the shock absorber a, and the moving direction thereof does not coincide with the vibration direction of the vehicle. Therefore, the valve body 7 is not excited in the moving direction by the vibration generated when the vehicle travels. However, the moving direction of the valve body 7 is not necessarily limited thereto. For example, the spool 7 may move obliquely with respect to a central axis X passing through the center of the piston rod 3, or may move along the central axis X.

Further, the buffer a of the present embodiment includes: a solenoid valve V; and a housing 4 that accommodates the soft side damping element FS and is formed integrally with the cylinder 1 in the housing 4. The state where the cylinder 1 and the housing 4 are integrally molded here means a state where the housing 4 is immovably fixed to the cylinder 1 when the shock absorber a is used alone, and these can be used as one (integral) member.

According to the above configuration, the inside of the housing 4 and the inside of the cylinder 1 can be communicated with each other by the hole formed in the portion where the housing 4 and the cylinder 1 are connected, such as the end cover 11. Therefore, since it is not necessary to connect the housing 4 and the cylinder 1 with a hose, it is possible to prevent an unexpected damping force from being generated due to a resistance when the liquid flows through the hose. Further, since the hose can be omitted, the cost can be reduced.

However, the method of attaching the damping force adjusting portion E including the housing 4 may be changed as appropriate. For example, a hose may be used to connect the housing 4 and the cylinder 1. In the present embodiment, the housing 4 and the reservoir tank T are connected by a hose, but the reservoir tank T may be integrally formed with the housing 4. In this case, the case 4, the head cover 11, the bracket 12 on the vehicle body side, and the tank T may be integrally formed.

While the preferred embodiments of the present invention have been illustrated in detail, modifications, variations and changes may be made without departing from the scope of the claims. This application claims priority based on japanese patent application No. 2019-038131 filed on 3/4/2019 to the present patent office, the entire contents of which are incorporated herein by reference.

Description of the symbols

A, A1 buffer

B bypass channel

L1 elongated side Chamber

L2 compression side chamber

FH hard side damping element

FS soft side damping element

T liquid storage tank

V-shaped electromagnetic valve

X center line

Line Z

1 cylinder

2 piston

3 piston rod

4 casing

6 support

6a port

7 valve core

8 force application spring

9 solenoid

20 extension side hard blade valve (blade valve)

21 compression side hard blade valve (blade valve)

22 orifice

50 extension side soft leaf valve (leaf valve)

51 compression side soft leaf valve (leaf valve)

52 orifice (Large diameter orifice)