阅读说明：本技术 电流控制装置 (Current control device ) 是由 铃木文规 笹尾和宽 于 2019-01-16 设计创作，主要内容包括：控制螺线管(44)的电流的电流控制装置(13)应用于电磁阀(31～36),该电磁阀(31～36)具有基于与输出液压相应的反馈力的自调压功能,并具有相对于阀芯(42)的行程变化的输出液压的变化程度相对急剧的液压突变区域(a1、a2)与相对缓慢的液压缓变区域(b)混合存在特性。电流控制装置(13)具备：驱动部(62),根据驱动信号以规定的通电周期对螺线管(44)进行通电；信号输出部(65),基于螺线管(44)的目标电流(Ir)生成并输出驱动信号；以及目标设定部(64),对目标电流(Ir)赋予高频振动振幅(Ad),以使其以比通电周期长的高频振动周期(Td)周期性地变化。目标设定部(64)根据与目标输出液压(Pr)对应的阀芯(42)的目标行程(Sr)和液压缓变区域(b)的位置关系来设定目标电流(Ir)。(A current control device (13) for controlling the current of a solenoid (44) is applied to solenoid valves (31-36), and the solenoid valves (31-36) have a self-pressure-adjusting function based on a feedback force corresponding to an output hydraulic pressure, and have a characteristic that a hydraulic pressure abrupt change region (a1, a2) in which the degree of change of the output hydraulic pressure relative to the stroke change of a spool (42) is relatively abrupt and a hydraulic pressure gradual change region (b) in which the degree of change is relatively slow are mixed. A current control device (13) is provided with: a drive unit (62) that energizes the solenoid (44) with a predetermined energization cycle in accordance with a drive signal; a signal output unit (65) that generates and outputs a drive signal on the basis of the target current (Ir) of the solenoid (44); and a target setting unit (64) that applies a dither amplitude (Ad) to the target current (Ir) so as to periodically change with a dither period (Td) that is longer than the energization period. A target setting unit (64) sets a target current (Ir) on the basis of the positional relationship between a target stroke (Sr) of a spool (42) corresponding to a target output hydraulic pressure (Pr) and a hydraulic pressure gradient region (b).)

1. A current control device is applied to solenoid valves (31-36) and controls the current of a solenoid (44), wherein the solenoid valves (31-36) have a self-pressure-adjusting function based on a feedback force corresponding to an output hydraulic pressure, and have a characteristic that a hydraulic pressure abrupt change region (a1, a2) in which the degree of change of the output hydraulic pressure relative to the change of the stroke of a spool (42) is relatively abrupt and a hydraulic pressure gradual change region (b) in which the degree of change of the output hydraulic pressure is relatively slow are mixed, and the current control device comprises:

a drive unit (62) that energizes the solenoid with a predetermined energization period in accordance with a drive signal;

a signal output unit (65) that generates and outputs the drive signal based on a target current (Ir) of the solenoid; and

a target setting unit (64, 74, 84) that applies a dither amplitude (Ad) to the target current so as to periodically change at a dither period (Td) that is longer than the energization period,

when the stroke of the spool corresponding to the target output hydraulic pressure (Pr) is set as the target stroke (Sr),

the target setting unit sets the target current according to a positional relationship between the target stroke and the hydraulic pressure gradual change region.

2. The current control device of claim 1,

the target setting unit (64, 84) determines the dither cycle based on the positional relationship between the target stroke and the hydraulic pressure retard region.

3. The current control device of claim 2,

the target setting unit includes:

an average calculation unit (66) that calculates an average target current (Irav) based on the target output hydraulic pressure;

an amplitude calculation unit (67) that calculates the dither amplitude based on the average target current;

an evaluation value calculation unit (68) that calculates an evaluation value (Ve) for determining the dither cycle, based on the positional relationship between the target stroke and the hydraulic pressure ramp region; and

and a period determination unit (69) that determines a predetermined first period (T1) as the dither period when the dither amplitude is smaller than the evaluation value, and determines a predetermined second period (T2) that is longer than the first period as the dither period when the dither amplitude is equal to or greater than the evaluation value.

4. The current control device of claim 1,

the target setting unit (74, 84) determines the dither amplitude based on the positional relationship between the target stroke and the hydraulic pressure gradual change region.

5. The current control device of claim 4,

the target setting unit includes:

an average calculation unit (66) that calculates an average target current based on the target output hydraulic pressure;

a first amplitude calculation unit (77) that calculates a first dither amplitude (Ad1) as a first provisional value of the dither amplitude on the basis of the average target current;

a second amplitude calculation unit (78) that calculates a second dither amplitude (Ad2) as a second provisional value of the dither amplitude, based on the positional relationship between the target stroke and the hydraulic pressure retard region; and

and an amplitude determination unit (79) that determines the first dither amplitude as the dither amplitude when the first dither amplitude is smaller than the second dither amplitude, and determines the second dither amplitude as the dither amplitude when the first dither amplitude is equal to or greater than the second dither amplitude.

6. The current control device of claim 5,

the target setting unit (84) has a period determining unit (89), and the period determining unit (89) determines a predetermined first period as the dither period when the first dither amplitude is smaller than the second dither amplitude, and determines a predetermined second period longer than the first period as the dither period when the first dither amplitude is equal to or larger than the second dither amplitude.

Technical Field

The present disclosure relates to a current control device.

Background

Conventionally, a current control device for controlling a current of a solenoid valve is known. Patent document 1 discloses a current control device that controls a current of a solenoid by a pulse width modulation signal (PWM signal). In patent document 1, a valve element of an electromagnetic valve is slightly vibrated by periodically changing a current at a dither (diter) period longer than a pulse period of a PWM signal, thereby suppressing the appearance of hysteresis characteristics due to static friction of the valve element.

Disclosure of Invention

The inventors of the present disclosure have found that, when the current of the solenoid is periodically changed at a high frequency oscillation cycle, the balance of the force applied to the spool of the solenoid valve is broken, and pulsation of the output hydraulic pressure increases, which may cause self-excited oscillation of the spool.

The present disclosure has been made in view of the above points, and an object thereof is to provide a current control device capable of suppressing the generation of self-excited vibration of a solenoid valve.

The inventors of the present disclosure have repeatedly studied the self-excited vibration of the valve body of the electromagnetic valve, and found that the mechanism of occurrence of this phenomenon is as follows. First, as preconditions for occurrence of a phenomenon, the following three conditions can be cited.

The solenoid valve of < precondition 1 > has a self-pressure-adjusting function based on a feedback force corresponding to an output hydraulic pressure.

To ensure linearity of the relationship between the current and the output hydraulic pressure, the solenoid valve has a characteristic in which a hydraulic pressure abrupt change region in which the degree of change in the output hydraulic pressure with respect to the change in the stroke of the spool is relatively rapid and a hydraulic pressure gradual change region in which the degree of change in the output hydraulic pressure is relatively slow coexist.

Precondition 3 applies dither amplitude to the target current of the solenoid so as to periodically change at a dither cycle longer than the energization switching cycle of the solenoid.

When current control is performed under these preconditions, the pulse width of the output hydraulic pressure varies depending on the stroke of the spool even if the same dither amplitude is applied to the target current. Therefore, when the stroke of the spool protrudes from the hydraulic pressure abrupt change region into the hydraulic pressure gradual change region, pulsation of the output hydraulic pressure changes. If the self-pressure-adjusting function is affected by this, and the return amount of the stroke increases, the balance of the forces acting on the valve element is lost. When the stroke of the spool from this state crosses the hydraulic pressure gradual change region and protrudes into the hydraulic pressure abrupt change region, the pulsation of the output hydraulic pressure further changes, and therefore the start of the increase of the output hydraulic pressure is delayed. When these operations are repeated, the force balance is further significantly disrupted, and the pulsation of the output hydraulic pressure is further increased. As a result, when the frequency of the valve body reaches the vicinity of the resonance frequency, the valve body oscillates as self-excited vibration. The inventors of the present disclosure have completed the present disclosure based on this finding.

The present disclosure relates to a current control device for controlling a current of a solenoid. The current control device is applied to a solenoid valve having a self-pressure-adjusting function based on a feedback force corresponding to an output hydraulic pressure, and having a characteristic in which a hydraulic pressure abrupt change region in which a degree of change of the output hydraulic pressure with respect to a stroke change of a spool is relatively abrupt and a hydraulic pressure gradual change region in which the degree of change is relatively slow coexist.

The current control device is provided with: a drive unit that energizes the solenoid with a predetermined energization cycle in accordance with a drive signal; a signal output unit that generates and outputs a drive signal based on a target current of the solenoid; and a target setting unit that applies a dither amplitude to the target current so as to periodically change at a dither cycle that is longer than the energization cycle. When the stroke of the spool corresponding to the target output hydraulic pressure is set as the target stroke, the target setting unit sets the target current according to the positional relationship between the target stroke and the hydraulic pressure ramp region.

Therefore, the target current can be set so that the force balance is not significantly impaired in a positional relationship in which the possibility of generating self-excited vibration is high. For example, the target current may be set such that the oscillation frequency of the spool is away from the resonance frequency, and the target current may be set such that the stroke of the spool does not cross the hydraulic pressure ramping region. Therefore, the generation of self-excited vibration of the solenoid valve can be suppressed.

Drawings

The above and other objects, features and advantages of the present disclosure will become more apparent with reference to the attached drawings and the following detailed description. The attached drawings are as follows,

fig 1 is a schematic diagram showing an automatic transmission to which a current control apparatus of a first embodiment is applied,

figure 2 is a cross-sectional view of a solenoid valve,

FIG. 3 is a characteristic diagram showing a relationship between a stroke of a spool of an electromagnetic valve and an output hydraulic pressure,

fig. 4 is an enlarged view of a main portion of the solenoid valve, and is a diagram showing a state where a stroke is in the first hydraulic pressure abrupt change region of fig. 3,

figure 5 is a cross-sectional view taken along line V-V of figure 4,

fig. 6 is an enlarged view of a main portion of the electromagnetic valve, and is a view showing a state where a stroke is in a hydraulic pressure gradually varying region of fig. 3,

figure 7 is a cross-sectional view taken along line VII-VII of figure 6,

fig. 8 is an enlarged view of a main portion of the solenoid valve, and is a view showing a state where a stroke is in the second hydraulic pressure abrupt change region of fig. 3,

figure 9 is a cross-sectional view taken along line IX-IX of figure 8,

FIG. 10 is a block diagram illustrating a functional part of the current control device,

fig 11 is a timing chart for explaining current control performed by the current control means,

fig. 12 is a stroke-output hydraulic pressure characteristic diagram illustrating the order in which the current control device calculates the evaluation value,

fig. 13 is a current-output hydraulic pressure characteristic diagram illustrating the order in which the current control means calculates the evaluation value,

FIG. 14 is a timing chart showing a state of equilibrium of the force of the spool valve when the current control means executes the current control,

fig. 15 is a flowchart for explaining a process performed by the current control device,

FIG. 16 is a timing chart showing a state of balance among current, stroke, output hydraulic pressure, and force when the current control means executes current control,

FIG. 17 is a block diagram illustrating a functional part of a current control device according to a second embodiment,

FIG. 18 is a timing chart showing a state of equilibrium of the force of the spool valve when the current control means executes the current control,

fig 19 is a flowchart for explaining a process performed by the current control device,

FIG. 20 is a timing chart showing a state of balance among current, stroke, output hydraulic pressure and force when the current control means executes current control,

FIG. 21 is a block diagram illustrating a functional part of a current control device according to a third embodiment,

FIG. 22 is a timing chart showing a state of equilibrium of the force of the spool when the current control means executes the current control,

fig 23 is a flowchart for explaining a process performed by the current control device,

fig. 24 is a timing chart for explaining a mechanism of generation of self-excited vibration of the spool valve by way of a comparative example,

fig. 25 is a timing chart showing a state of balance among the current, the stroke, the output hydraulic pressure, and the force when the current control is executed in the comparative method.

Detailed Description

Hereinafter, a plurality of embodiments will be described with reference to the drawings. The same reference numerals are given to the substantially same components of the embodiments, and descriptions thereof are omitted.

[ first embodiment ]

The current control device of the first embodiment is applied to an automatic transmission shown in fig. 1. First, the automatic transmission 10 will be explained. The automatic transmission 10 includes a transmission mechanism 11, a hydraulic circuit 12, and a current control device 13. The transmission mechanism 11 has a plurality of friction elements 21 to 26 including, for example, clutches and brakes, and changes the transmission ratio stepwise by selectively engaging each of the friction elements 21 to 26. The hydraulic circuit 12 includes a plurality of solenoid valves 31 to 36 that regulate pressure of hydraulic oil fed under pressure from an oil pump 28 and supply the hydraulic oil to the friction elements 21 to 26.

As shown in fig. 2, the solenoid valve 31 includes a sleeve 41, a spool valve 42 serving as a valve body, a spring 43 that biases the spool valve 42 in one axial direction, a solenoid 44 that generates an electromagnetic force that drives the spool valve 42 in the other axial direction, and a plunger 45 provided inside the solenoid 44.

The sleeve 41 has an input port 46, an output port 47, a drain port 48, and a feedback port 49. A part of the working oil output from the output port 47 flows into the feedback port 49. The hydraulic oil flowing into the feedback port 49 generates a feedback force corresponding to the magnitude of the output hydraulic pressure.

The plunger 45 moves in the axial direction in accordance with the magnitude of the excitation current of the solenoid 44. The spool valve 42 moves in the axial direction together with the plunger 45, and changes the degree of communication between the input port 46 and the output port 47 and the degree of communication between the output port 47 and the drain port 48. The IN land 51 opens and closes the input port 46. The EX shoulder 52 opens and closes the discharge port 48.

The stroke of the spool 42 is a position where the electromagnetic force of the solenoid 44, the biasing force of the spring 43, and the feedback force corresponding to the output hydraulic pressure of the hydraulic oil flowing into the feedback port 49 are balanced with each other. The solenoid valve 31 has a self-pressure-adjusting function based on a feedback force.

As shown in fig. 3, the output hydraulic pressure varies corresponding to the stroke of the spool valve 42. As shown in this relationship, the solenoid valve 31 has a characteristic in which the hydraulic pressure abrupt change regions a1 and a2, in which the degree of change in the output hydraulic pressure with respect to the change in the stroke is relatively abrupt, and the hydraulic pressure gradual change region b, in which the degree of change in the output hydraulic pressure is relatively slow, coexist.

As shown in fig. 4 and 5, the hydraulic pressure abrupt change region a1 of fig. 3 is the entire region of the stroke range (i.e., the EX notch communication range a1) corresponding to the "state in which the discharge port 48 communicates with the output port 47 only via the EX notch 54 of the EX land 52". As shown IN fig. 6 and 7, the hydraulic pressure gradual change region B IN fig. 3 is the entire region of the stroke range (i.e., the overlap range B) corresponding to the "state IN which the sealing of the input port 46 by the IN land 51 and the sealing of the EX land 52 by the EX land 52 overlap". As shown IN fig. 8, 9, the hydraulic pressure mutation region a2 of fig. 3 is a part of the stroke range (i.e., the IN notch communication range a2) corresponding to the "state where the input port 46 communicates with the output port 47 only via the IN notch 53 of the IN shoulder 51", and is a region IN this IN notch communication range a2 adjacent to the overlap range B.

The EX open range C1 of fig. 3 is a stroke range corresponding to the "state IN which the discharge port 48 communicates with the output port 47 not only via the EX land 52 but also via the space between the EX land 52 and the IN land 51". The IN open range C2 of fig. 3 is a stroke range corresponding to the "state IN which the input port 46 communicates with the output port 47 not only via the IN land 51 but also via the space between the EX land 52 and the IN land 51".

As shown in fig. 10, the current control device 13 includes a microcomputer 61, a drive circuit 62 as a drive unit, a current detection unit 63 that detects an actual current of the solenoid 44, and the like. The microcomputer 61 executes a program process based on output values of the current detection unit 63, other devices not shown, and sensors. The microcomputer 61 has: a target setting unit 64 for setting a target current of the solenoid 44 according to a target output hydraulic pressure of the solenoid valves 31 to 36; and a signal output section 65 that generates and outputs a drive signal based on the target current. The signal output unit 65 generates a drive signal so that the difference between the current of the solenoid 44 and the target current is small. The drive circuit 62 energizes the solenoid 44 with a predetermined energization cycle in accordance with the drive signal. Thus, the current control device 13 controls the current of the solenoid 44.

(Current control)

Next, the current control performed by the current control device 13 will be described. The current control device 13 controls the current of the solenoid 44 by a pulse width modulation signal (PWM signal). As shown in fig. 11, the solenoid 44 is energized and then de-energized repeatedly in the PWM period Tpwm, and the average value of the current I of the solenoid 44 is maintained near the average target current Irav. At this time, the dither amplitude Ad is given to the target current Ir so that the current I periodically changes with a dither period Td longer than the PWM period Tpwm. This causes the spool 42 to vibrate slightly, and maintains the dynamic friction state of the spool 42.

By periodically changing the current of the solenoid 44 at the dither cycle Td in this way, the hysteresis characteristic due to the static friction of the spool valve 42 can be suppressed from being exhibited. On the other hand, the force balance of the spool 42 is lost, and pulsation of the output hydraulic pressure becomes large, which may cause self-excited vibration of the spool 42. The mechanism of occurrence of this phenomenon is as follows.

As preconditions for generating self-excited vibration, the following three conditions can be cited.

The solenoid valve 31 of < precondition 1 > has a self-pressure-adjusting function based on the feedback force corresponding to the output hydraulic pressure.

To ensure linearity of the relationship between the current and the output hydraulic pressure, the solenoid valve 31 has a characteristic in which abrupt hydraulic pressure transition regions a1 and a2, in which the degree of change in the output hydraulic pressure with respect to the change in the stroke is relatively rapid, and a slow hydraulic pressure transition region b, coexist.

Precondition 3 > the dither amplitude Ad is given to the target current Ir of the solenoid 44 so as to periodically change with a dither period Td that is longer than the energization switching period of the solenoid 44.

When the current control is performed under these preconditions, even if the same dither amplitude is applied to the target current, the pulse width of the output hydraulic pressure differs depending on the stroke of the spool 42. Therefore, at time t101 in fig. 24, when the stroke of the spool 42 protrudes from the hydraulic pressure abrupt change region a1 into the hydraulic pressure gradual change region b, the pulsation of the output hydraulic pressure changes. If the self-pressure adjusting function is activated by this influence and the return amount of the stroke increases, the balance of the forces acting on the spool valve 42 is lost. When the stroke crosses the hydraulic pressure gradual change region b and protrudes into the hydraulic pressure abrupt change region a2 at time t102 in fig. 24 from this state, the pulsation of the output hydraulic pressure also changes. When this is repeated, the start of the rise of the output hydraulic pressure is delayed, the force balance is further significantly disrupted, and the pulsation of the output hydraulic pressure also increases. As a result, when the oscillation frequency of the spool 42 reaches the vicinity of the resonance frequency at the vicinity of time t103 in fig. 24, the spool oscillates as self-excited oscillation. The target setting portion 64 of the current control device 13 includes a functional portion for suppressing generation of such self-excited vibration.

(function part of Current control device)

Next, the target setting unit 64 will be described with reference to fig. 10. The target setting unit 64 gives the dither amplitude Ad to the target current Ir so as to periodically change with a dither period Td longer than the energization switching period (i.e., PWM period Tpwm) of the drive circuit 62. The target setting unit 64 sets the dither cycle Td of the target current Ir based on the positional relationship between the target stroke Sr and the hydraulic pressure gradual change region b. The target stroke Sr is a stroke of the spool 42 corresponding to the target output hydraulic pressure Pr. Specifically, the target setting unit 64 includes an average calculation unit 66, an amplitude calculation unit 67, an evaluation value calculation unit 68, and a cycle determination unit 69.

The average calculation portion 66 calculates the average target current Irav based on the target output hydraulic pressure Pr. In the first embodiment, the target output hydraulic pressure Pr is a value that is input from the outside, but the target output hydraulic pressure Pr is not limited to this, and may be calculated inside the current control device 13.

The amplitude calculation section 67 calculates the dither amplitude Ad based on at least the average target current Irav. In the first embodiment, the amplitude calculation unit 67 calculates the dither amplitude Ad based on the average target current Irav and the oil temperature To of the hydraulic oil supplied To the solenoid valves 31 To 36.

The evaluation value calculation unit 68 calculates the evaluation value Ve for determining the dither cycle Td based on the positional relationship between the target stroke Sr and the hydraulic pressure retard region b. In the first embodiment, the evaluation value Ve is the amount of change in current from the target stroke Sr to the stroke immediately before the hydraulic pressure gradual change region b is crossed. Specifically, in fig. 12, the stroke from the target stroke Sr to immediately before the hydraulic pressure gradual change region b is set to S2. Then, from the stroke-output hydraulic pressure characteristic of fig. 12, the output hydraulic pressure P1 corresponding to the target stroke Sr and the output hydraulic pressure P2 corresponding to the stroke S2 are obtained. Next, from the current-output hydraulic pressure characteristic shown in fig. 13, a current I1 corresponding to the output hydraulic pressure P1 and a current I2 corresponding to the output hydraulic pressure P2 are obtained. The evaluation value Ve is a value obtained by subtracting the current I1 from the current I2.

The period determination unit 69 compares the dither amplitude Ad with the evaluation value Ve. When the dither amplitude Ad is smaller than the evaluation value Ve, the predetermined first period T1 is determined as the dither period Td. On the other hand, when the dither amplitude Ad is equal to or greater than the evaluation value Ve, a predetermined second period T2 longer than the first period T1 is determined as the dither period Td. In order to suppress the appearance of the hysteresis characteristic due to the static friction of the spool valve 42, the first period T1 and the second period T2 are set to values that can maintain the dynamic friction state of the spool valve 42.

As described above, the target setting unit 64 calculates the evaluation value Ve based on the positional relationship between the target stroke Sr and the hydraulic pressure gradual change region b, compares the evaluation value Ve with the dither amplitude Ad, and determines the dither cycle Td based on the comparison result. For example, when the dither amplitude Ad is equal to or greater than the evaluation value Ve, it is determined that the positional relationship between the target stroke Sr and the hydraulic pressure gradual change region b is a positional relationship in which the self-excited vibration is highly likely to occur. Then, the dither period Td is set to a relatively long second period T2 to shift the vibration frequency of the spool valve 42 away from the resonance frequency. By extending the dither cycle Td in this manner, even if the equilibrium state becomes unstable due to slight disruption of the force balance as shown at times t1 to t2 and t3 to t4 in fig. 14, a time until the force balance is restored can be ensured. Therefore, the stable states at times t2 to t3 and t4 to t5 in fig. 14 can be ensured.

The functional units 64 to 69 of the current control device 13 may be realized by hardware processing using a dedicated logic circuit, by software processing using a program stored in advance in a memory such as a computer-readable non-transitory tangible recording medium and executed by a CPU, or by a combination of both. Which part of each of the functional units 64 to 69 is realized by hardware processing and which part is realized by software processing can be appropriately selected.

(processing performed by Current control means)

Next, a process executed by the current control device 13 to set the target current will be described with reference to fig. 15. The routine shown in fig. 15 is repeatedly executed from the start of the current control device 13 to the stop of the start. Hereinafter, "S" denotes a step.

In S1 of fig. 15, the average target current Irav is calculated. After S1, the process moves to S2.

In S2, the dither amplitude Ad is calculated based on the average target current Irav and the oil temperature To. After S2, the process moves to S3.

In S3, an evaluation value Ve for determining the dither cycle Td is calculated based on the positional relationship between the target stroke Sr and the hydraulic pressure gradient region b. After S3, the process moves to S4.

In S4, it is determined whether or not the dither amplitude Ad is smaller than the evaluation value Ve. When the dither amplitude Ad is smaller than the evaluation value Ve (S4: YES), the process proceeds to S5. When the dither amplitude Ad is equal to or greater than the evaluation value Ve (S4: NO), the process proceeds to S6.

In S5, a predetermined first period T1 is determined as a dither period Td. After S5, the process moves to S7.

In S6, a predetermined second period T2 longer than the first period T1 is determined as a dither period Td. After S6, the process moves to S7.

In S7, the target current Ir is set based on the average target current Irav, the dither amplitude Ad, and the dither period Td. After S7, the process exits the routine of fig. 15.

Next, the change of each value (i.e., the balance state of the current, the stroke, the output hydraulic pressure, and the force) in the current control by the current control device 13 is shown by comparison with the conventional comparison method. Fig. 25 is a timing chart showing changes in the respective values in a comparative method in which the dither cycle is set to a constant value regardless of the positional relationship between the target stroke and the hydraulic pressure ramp region. In fig. 25, after the average target current Irav is changed at time t111, the current changes so as to follow the average target current Irav. Thereafter, at time t112, the stroke protrudes from the hydraulic pressure abrupt change region a2 into the hydraulic pressure gradual change region b, and at time t113, pulsation of the output hydraulic pressure increases as the stroke crosses the hydraulic pressure gradual change region b. During this period, the equilibrium state of the force is unstable because the current amplitude appears soon after the equilibrium state of the force is stable. When the oscillation frequency of the stroke reaches the vicinity of the resonance frequency at the vicinity of time t114, the stroke oscillates as self-excited oscillation.

On the other hand, in fig. 16 showing the change in the values of the first embodiment, after the average target current Irav is changed at time t11, the current changes so as to follow the average target current Irav. Thereafter, at time t12, the stroke protrudes from the hydraulic pressure abrupt change region a2 into the hydraulic pressure gradual change region b, and the balance of forces is slightly lost, so that the equilibrium state becomes unstable. However, since the dither period Td is set to be relatively long and a time until the balance of force is restored is secured, the balance of force is not further significantly disrupted and the state is immediately stabilized.

(Effect)

As described above, in the first embodiment, the current control device 13 is applied to the solenoid valves 31 to 36, and the solenoid valves 31 to 36 have a self-pressure-adjusting function based on the feedback force corresponding to the output hydraulic pressure, and have a characteristic in which the hydraulic pressure abrupt change regions a1 and a2, in which the degree of change of the output hydraulic pressure with respect to the stroke change of the spool 42 is relatively abrupt, and the hydraulic pressure gradual change region b, in which the change degree is relatively slow, coexist.

The current control device 13 includes: a drive circuit 62 that energizes the solenoid 44 at a predetermined energization cycle based on a drive signal; a signal output unit 65 that generates and outputs a drive signal based on the target current Ir of the solenoid 44; and a target setting unit 64 for applying the dither amplitude Ad to the target current Ir so as to periodically change with a dither period Td that is longer than the energization period of the drive circuit 62. The target setting unit 64 sets the target current Ir based on the positional relationship between the target stroke Sr and the hydraulic pressure gradual change region b.

Therefore, if the target current Ir is in a positional relationship in which the possibility of generating self-excited vibration is high, the target current Ir can be set so that the balance of forces is not significantly impaired. Therefore, the generation of self-excited vibration of the solenoid valve can be suppressed.

In the first embodiment, the target setting unit 64 determines the dither cycle Td based on the positional relationship between the target stroke Sr and the hydraulic pressure gradually varying region b. Thus, in order to obtain a positional relationship in which the possibility of the occurrence of self-excited vibration is high, the target current is set so that the vibration frequency of the spool 42 is away from the resonance frequency, whereby the occurrence of self-excited vibration can be suppressed.

In the first embodiment, the target setting unit 64 includes an average calculation unit 66, an amplitude calculation unit 67, an evaluation value calculation unit 68, and a cycle determination unit 69. The average calculation portion 66 calculates the average target current Irav based on the target output hydraulic pressure Pr. The amplitude calculation section 67 calculates the dither amplitude Ad based on the average target current Irav. The evaluation value calculation unit 68 calculates the evaluation value Ve for determining the dither cycle Td based on the positional relationship between the target stroke Sr and the hydraulic pressure retard region b. When the dither amplitude Ad is smaller than the evaluation value Ve, the period determination unit 69 determines the predetermined first period T1 as the dither period Td. On the other hand, when the dither amplitude Ad is equal to or greater than the evaluation value Ve, a predetermined second period T2 longer than the first period T1 is determined as the dither period Td.

Therefore, if the high-frequency vibration amplitude Ad, which is a positional relationship in which the possibility of generating self-excited vibration is high, is equal to or greater than the evaluation value Ve, the high-frequency vibration period Td is set relatively long so that the vibration frequency of the spool valve 42 is away from the resonance frequency. By extending the dither period Td in this manner, even if the force balance of the spool valve 42 is slightly lost and the balanced state becomes unstable, a time until the force balance is restored can be secured. Therefore, the generation of self-excited vibration of the solenoid valve can be suppressed.

[ second embodiment ]

In the second embodiment, as shown in fig. 17, the target setting unit 74 of the current control device 73 sets the dither amplitude Ad of the target current Ir in accordance with the positional relationship between the target stroke Sr and the hydraulic pressure gradual change region b. Specifically, the target setting unit 74 includes an average calculation unit 66, a first amplitude calculation unit 77, a second amplitude calculation unit 78, and an amplitude determination unit 79.

The first amplitude calculation section 77 calculates the first dither amplitude Ad1 as a first provisional value of the dither amplitude Ad based on at least the average target current Irav. In the first embodiment, the first amplitude calculation section 77 calculates the first dither amplitude Ad1 based on the average target current Irav and the oil temperature To.

The second amplitude calculation unit 78 calculates the second dither amplitude Ad2 as a second provisional value of the dither amplitude Ad based on the positional relationship between the target stroke Sr and the hydraulic pressure retard region b. In the second embodiment, the second dither amplitude Ad2 is the amount of current change from the target stroke Sr to the stroke immediately before the hydraulic pressure gradual change region b, as in the evaluation value Ve in the first embodiment.

The amplitude determining section 79 compares the first dither amplitude Ad1 with the second dither amplitude Ad 2. Then, when the first dither amplitude Ad1 is smaller than the second dither amplitude Ad2, the first dither amplitude Ad1 is determined as the dither amplitude Ad. On the other hand, when the first dither amplitude Ad1 is equal to or greater than the second dither amplitude Ad2, the second dither amplitude Ad2 is determined as the dither amplitude Ad. In the second embodiment, the dither period Td is set to a predetermined value.

As described above, the target setting unit 74 calculates the second dither amplitude Ad2 based on the positional relationship between the target stroke Sr and the hydraulic pressure retard region b, compares the first dither amplitude Ad1 with the second dither amplitude Ad2, and determines the dither amplitude Ad from the comparison result. For example, when the first dither amplitude Ad1 is equal to or greater than the second dither amplitude Ad2, it is determined that the positional relationship between the target stroke Sr and the hydraulic pressure retard region b is a positional relationship in which the possibility of self-excited vibration is high. Then, the dither amplitude Ad is set to a second dither amplitude Ad2 that is relatively small so that the stroke of the spool valve 42 does not cross the hydraulic ramp region b. By reducing the second dither amplitude Ad2 in this way, even if the equilibrium state becomes unstable due to slight disruption of the force balance as shown at times t21 to t22 and t23 to t24 in fig. 18, the force balance is restored immediately, and the time for the unstable state is short. Therefore, the stable states at times t22 to t23 and t24 to t25 in fig. 18 can be ensured.

(processing performed by Current control means)

Next, a process executed by the current control device 73 to set the target current will be described with reference to fig. 19. The routine shown in fig. 19 is repeatedly executed from the start of the current control device 73 to the stop of the start.

In S11 of fig. 19, the same processing as in S1 of fig. 15 of the first embodiment is performed. After S11, the process moves to S12.

In S12, the first dither amplitude Ad1 is calculated based on the average target current Irav and the oil temperature To. After S12, the process moves to S13.

In S13, the second dither amplitude Ad2 is calculated as the second provisional value of the dither amplitude Ad based on the positional relationship between the target stroke Sr and the hydraulic pressure retard region b. After S13, the process moves to S14.

In S14, it is determined whether the first dither amplitude Ad1 is less than the second dither amplitude Ad 2. In the case where the first dither amplitude Ad1 is smaller than the second dither amplitude Ad2 (S14: yes), the process moves to S15. If the first dither amplitude Ad1 is equal to or greater than the second dither amplitude Ad2 (S14: no), the process proceeds to S16.

In S15, the first dither amplitude Ad1 is determined as the dither amplitude Ad. After S15, the process moves to S17.

In S16, the second dither amplitude Ad2 is determined as the dither amplitude Ad. After S16, the process moves to S17.

In S17, the target current Ir is set based on the average target current Ir, the dither amplitude Ad, and the dither period Td. After S17, the process exits the routine of fig. 19.

Next, the change of each value (i.e., the balance state of the current, the stroke, the output hydraulic pressure, and the force) in the current control by the current control device 73 is shown by comparison with the conventional comparison method. As described above, in the comparative method shown in fig. 25, the equilibrium state of the force is unstable because the current has an amplitude immediately after the equilibrium state of the force is stable. When the oscillation frequency of the stroke reaches the vicinity of the resonance frequency at the vicinity of time t114, the stroke oscillates as self-excited oscillation.

On the other hand, in fig. 20 showing the change in the values of the second embodiment, after the average target current Irav is changed at time t31, the current changes so as to follow the average target current Irav. After that, after the current catches up with the average target current Irav, the stroke does not protrude from the hydraulic pressure abrupt change region a2 into the hydraulic pressure gradual change region b. Therefore, the balance of forces is not significantly disrupted, and a stable region can be ensured.

(Effect)

As described above, in the second embodiment, the target setting unit 74 sets the target current Ir according to the positional relationship between the target stroke Sr and the hydraulic pressure gradually varying region b. Therefore, as in the first embodiment, the generation of self-excited vibration of the solenoid valve can be suppressed.

In the second embodiment, the target setting unit 74 determines the dither amplitude Ad based on the positional relationship between the target stroke Sr and the hydraulic pressure gradual change region b. Thus, in order to obtain a positional relationship in which the self-excited vibration is likely to occur, the target current Ir is set so that the stroke of the spool 42 does not cross the hydraulic pressure retard region b, whereby the self-excited vibration can be suppressed from occurring.

In the first embodiment, the target setting unit 64 includes the average calculation unit 66, the first amplitude calculation unit 77, the second amplitude calculation unit 78, and the amplitude determination unit 79. The first amplitude calculation section 77 calculates the first dither amplitude Ad1 as a first provisional value of the dither amplitude Ad based on the average target current Irav. The second amplitude calculation unit 78 calculates the second dither amplitude Ad2 as a second provisional value of the dither amplitude Ad based on the positional relationship between the target stroke Sr and the hydraulic pressure retard region b. When the first dither amplitude Ad1 is smaller than the second dither amplitude Ad2, the amplitude determining unit 79 determines the first dither amplitude Ad1 as the dither amplitude Ad. On the other hand, when the first dither amplitude Ad1 is equal to or greater than the second dither amplitude Ad2, the second dither amplitude Ad2 is determined as the dither amplitude Ad.

Therefore, in order to achieve a positional relationship in which the possibility of self-excited vibration is high, that is, when the first dither amplitude Ad1 is equal to or greater than the second dither amplitude Ad2, the dither amplitude Ad is set relatively small so that the stroke of the spool 42 does not cross the hydraulic pressure gradually varying region b. By thus reducing the dither amplitude Ad, the force balance of the spool valve 42 is not significantly disrupted. Therefore, the generation of self-excited vibration of the solenoid valve can be suppressed.

[ third embodiment ]

In the third embodiment, as shown in fig. 21, the target setting unit 84 of the current control device 83 sets the dither cycle Td and the dither amplitude Ad of the target current Ir in accordance with the positional relationship between the target stroke Sr and the hydraulic pressure gradual change region b. Specifically, the target setting unit 84 includes an average calculation unit 66, a first amplitude calculation unit 77, a second amplitude calculation unit 78, an amplitude determination unit 79, and a cycle determination unit 89.

The period determination section 89 compares the first dither amplitude Ad1 with the second dither amplitude Ad 2. When the first dither amplitude Ad1 is smaller than the second dither amplitude Ad2, the predetermined first period T1 is determined as the dither period Td. On the other hand, when the first dither amplitude Ad1 is equal to or greater than the second dither amplitude Ad2, a predetermined second period T2 longer than the first period T1 is determined as the dither period Td.

As described above, the target setting unit 74 calculates the second dither amplitude Ad2 based on the positional relationship between the target stroke Sr and the hydraulic pressure ramp region b, compares the first dither amplitude Ad1 with the second dither amplitude Ad2, and determines the dither amplitude Ad and the dither cycle Td based on the comparison result. For example, when the first dither amplitude Ad1 is equal to or greater than the second dither amplitude Ad2, it is determined that the positional relationship between the target stroke Sr and the hydraulic pressure retard region b is a positional relationship in which the possibility of self-excited vibration is high. Then, the dither amplitude Ad is set to a relatively small second dither amplitude Ad2 so that the stroke of the spool valve 42 does not cross the hydraulic ramp region b, and the dither period Td is set to a relatively long second period T2 so that the vibration frequency of the spool valve 42 is away from the resonance frequency. By reducing the second dither amplitude Ad2 and extending the dither period Td in this way, even if the equilibrium state becomes unstable due to slight disruption of the force balance as shown at times t41 to t42 and t43 to t44 in fig. 22, the time until the force balance is restored can be ensured, and the force balance is restored immediately. Therefore, the stable states at times t42 to t43 and t44 to t45 in fig. 22 can be ensured.

(processing performed by Current control means)

Next, a process executed by the current control device 83 to set the target current will be described with reference to fig. 23. The routine shown in fig. 23 is repeatedly executed from the start of the current control device 83 to the stop of the start.

In S21 to S25 and S27 of fig. 22, the same processing as in S11 to S16 of fig. 19 of the second embodiment is performed.

In S26 after S25, a predetermined first period T1 is determined as a dither period Td. After S26, the process moves to S29.

In S28 after S27, a predetermined second period T2 longer than the first period T1 is determined as a dither period Td. After S28, the process moves to S29.

In S29, the target current Ir is set based on the average target current Ir, the dither amplitude Ad, and the dither period Td. After S29, the process exits the routine of fig. 23.

(Effect)

As described above, in the third embodiment, the target setting unit 84 sets the target current Ir according to the positional relationship between the target stroke Sr and the hydraulic pressure gradual change region b. Therefore, as in the first and second embodiments, the generation of self-excited vibration of the solenoid valve can be suppressed.

In the third embodiment, the target setting unit 84 sets the dither cycle Td and the dither amplitude Ad of the target current Ir according to the positional relationship between the target stroke Sr and the hydraulic pressure gradual change region b. Therefore, in order to obtain a positional relationship in which the self-excited vibration is likely to occur, the target current Ir is set so that the stroke of the spool 42 does not cross the hydraulic pressure ramp region b, and the target current is set so that the vibration frequency of the spool 42 is away from the resonance frequency, whereby the occurrence of the self-excited vibration can be suppressed more effectively than in the first and second embodiments.

[ other embodiments ]

In another embodiment, the target setting unit may determine whether or not there is a possibility of generating self-excited vibration based on whether or not the distance between the target stroke and the hydraulic pressure gradual change region is equal to or less than a threshold value, and when the distance is equal to or less than the threshold value, the dither cycle or the dither amplitude may be set smaller than when not.

In other embodiments, the current control of the solenoid is not limited to the PWM control, and may be other dither chopper control. In another embodiment, the self-pressure adjusting function based on the feedback force corresponding to the output hydraulic pressure may be realized by detecting the magnitude of the output hydraulic pressure and applying a force corresponding to the detected value to the spool using, for example, an electromagnetic force.

The control unit and the method thereof described in the present disclosure may be realized by a special purpose computer provided with a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the control unit and the method thereof described in the present disclosure may be implemented by a dedicated computer provided with one or more dedicated hardware logic circuits included in a processor. Alternatively, the control unit and the method thereof described in the present disclosure may be implemented by one or more special purpose computers including a combination of a processor and a memory programmed to execute one or more functions and a processor including one or more hardware logic circuits. The computer program may be stored in a non-transitory tangible recording medium that can be read by a computer as instructions to be executed by the computer.

The present disclosure is described based on the embodiments. However, the present disclosure is not limited to the embodiment and the configuration. The present disclosure also includes various modifications and variations within an equivalent range. In addition, various combinations and modes, and further, other combinations and modes including only one element, more than one element, or less than one element also fall within the scope and the idea of the present disclosure.