阅读说明：本技术 电流控制装置 (Current control device ) 是由 铃木文规 水野雄太 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)应用于具有基于与输出液压相应的反馈力的自调压功能的电磁阀(31～36)。电流控制装置(13)具备：电流检测部(63),检测螺线管(44)的实际电流；驱动部(62),根据驱动信号以规定的通电周期(Tpwm)对螺线管(44)进行通电；信号输出部(65),以实际电流追随目标电流(Ir)的方式设定驱动信号的占空比,生成并输出该驱动信号；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；以及振动判定部(66),基于实际电流的举动,判定与通过对目标电流(Ir)赋予高频振动振幅(Ad)而产生的微振动相比是否产生了过大的振动或者是否已转移至过大的振动。(A current control device (13) for controlling the current of a solenoid (44) is applied to solenoid valves (31-36) having a self-pressure-adjusting function based on a feedback force corresponding to an output hydraulic pressure. A current control device (13) is provided with: a current detection unit (63) that detects the actual current of the solenoid (44); a drive unit (62) that energizes the solenoid (44) with a predetermined energization cycle (Tpwm) in accordance with a drive signal; a signal output unit (65) that sets the duty ratio of the drive signal so that the actual current follows the target current (Ir), and generates and outputs the drive signal; a target setting unit (64) that applies a dither amplitude (Ad) to the target current (Ir) so as to periodically change the dither amplitude with a dither period (Td) that is longer than the energization period; and a vibration determination unit (66) that determines, based on the behavior of the actual current, whether or not excessive vibration has occurred or has shifted to excessive vibration, as compared to the micro-vibration that is generated by applying a dither amplitude (Ad) to the target current (Ir).)

1. A current control device is applied to solenoid valves (31-36) and controls current of a solenoid (44), wherein the solenoid valves (31-36) have a self-pressure-adjusting function based on feedback force corresponding to output hydraulic pressure, and the current control device comprises:

a current detection unit (63) that detects the actual current of the solenoid;

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

a signal output unit (65) that generates and outputs the drive signal by setting the duty ratio of the drive signal so that the actual current follows a target current (Ir);

a target setting unit (64, 94, 104) 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; and

and a vibration determination unit (66, 86) that determines, based on the behavior of the actual current, whether or not excessive vibration has occurred or has shifted to the excessive vibration, as compared to the micro-vibration that is generated by applying the dither amplitude to the target current.

2. The current control device of claim 1,

when the absolute value of the change amount (Δ I) of the actual current over a predetermined time is equal to or greater than a predetermined first threshold value (Th1) and the absolute value of the change amount (Δ D) of the duty ratio over the predetermined time is equal to or greater than a predetermined second threshold value (Th2), the vibration determination unit (66) determines whether the excessive vibration has occurred or whether the excessive vibration has shifted to the excessive vibration, based on the behavior of the actual current.

3. The current control device of claim 2,

the vibration determination unit determines that the excessive vibration has occurred or has shifted to the excessive vibration when a direction of change of the actual current over the predetermined time is different from a direction of change of the duty ratio over the predetermined time.

4. The current control device of claim 1,

when the amount of change of the actual current over a predetermined period of time is not within a design value range determined based on the amount of change of the duty ratio over the predetermined period of time, the vibration determination unit (86) determines that the excessive vibration has occurred or has shifted to the excessive vibration.

5. The current control device according to any one of claims 1 to 4,

when it is determined that the excessive vibration has occurred or has shifted to the excessive vibration, the target setting unit (64) reduces the dither amplitude as compared with a case where the determination is negative.

6. The current control device according to any one of claims 1 to 4,

when it is determined that the excessive vibration has occurred or has shifted to the excessive vibration, the target setting unit (94) extends the dither cycle as compared to when the determination is negative.

7. The current control device according to any one of claims 1 to 4,

the target setting unit (104) sets the target current to zero when it is determined that the excessive vibration has occurred or has shifted to the excessive vibration.

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, it is determined whether or not coupled vibration is generated in the hydraulic circuit based on an output signal of the hydraulic pressure sensor.

Disclosure of Invention

When excessive vibration such as coupling vibration or self-excited vibration is generated in the solenoid valve, the output hydraulic pressure largely pulsates, and controllability is degraded. Therefore, it is important to detect the generation of excessive vibration and implement countermeasures. This determination can be performed based on the detection value of the hydraulic pressure sensor as disclosed in patent document 1. However, providing the hydraulic pressure sensor is not preferable because it increases the size, weight, and cost of the hydraulic circuit.

The present disclosure has been made in view of the above-described points, and an object thereof is to provide a current control device capable of detecting the occurrence of excessive vibration of an electromagnetic valve without a hydraulic pressure sensor.

The inventors of the present disclosure have repeatedly studied the excessive vibration of the solenoid valve, and found that the actual current of the solenoid at the time of generation and transition thereof shows behavior different from that at the normal time. When the pulsation of the output hydraulic pressure increases due to vibration, the phase of the stroke change of the spool becomes slower than when the pulsation of the output hydraulic pressure is small, and the inductance of the solenoid differs. Therefore, even if the duty ratio of the drive signal is set in the same manner as when the pulsation of the output hydraulic pressure is small, the current actually flowing through the solenoid differs. 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 an electromagnetic valve having a self-pressure-adjusting function based on a feedback force corresponding to an output hydraulic pressure. The current control device includes a current detection unit, a drive unit, a signal output unit, a target setting unit, and a vibration determination unit.

The current detection unit detects an actual current of the solenoid. The drive unit energizes the solenoid with a predetermined energization cycle in response to the drive signal. The signal output unit sets the duty ratio of the drive signal so that the actual current follows the target current, and generates and outputs the drive signal. The target setting unit applies a dither amplitude to the target current so as to periodically change at a dither period longer than the energization period. The vibration determination unit determines, based on the behavior of the actual current, whether or not an excessive vibration is generated or has shifted to an excessive vibration, as compared to a micro-vibration generated by applying a dither amplitude to the target current.

By performing the determination based on the behavior of the actual current in this manner, it is possible to detect the occurrence of excessive vibration of the solenoid valve without the need for a hydraulic pressure sensor.

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 view showing a state where a stroke is in the first hydraulic pressure gradually varying 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 solenoid valve, and is a view showing a state where a stroke is in a hydraulic pressure abrupt change 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 gradually varying 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 showing a current and a target current when the current control means executes current control,

FIG. 12 is a graph showing a relationship between a stroke slope and an actual current change amount when the duty change amount is in a predetermined range for a steady period,

FIG. 13 is a graph showing a relationship between a stroke slope and an actual current change amount when the duty change amount is in a predetermined range for a vibration transition period,

FIG. 14 is a graph showing a relationship between a stroke slope and an actual current change amount when the duty change amount is within a predetermined range for an excessive vibration generation period,

FIG. 15 is a timing chart showing a duty ratio, an actual current, a stroke, and a stroke slope in current control in a steady state,

fig. 16 is a timing chart for explaining the processing performed by the current control device,

FIG. 17 is a timing chart showing a current and a target current when the current control device detects excessive vibration,

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 block diagram illustrating a functional part of a current control device according to a second embodiment,

FIG. 21 is a flowchart for explaining a process performed by the current control device of FIG. 20,

FIG. 22 is a block diagram illustrating a functional part of a current control device according to a third embodiment,

FIG. 23 is a timing chart showing a current and a target current when the current control device of FIG. 22 detects excessive vibration,

FIG. 24 is a timing chart showing a force equilibrium state of the spool valve when the current control apparatus of FIG. 22 executes the current control,

FIG. 25 is a flowchart for explaining a process performed by the current control device of FIG. 22,

FIG. 26 is a block diagram illustrating a functional part of a current control device according to a fourth embodiment,

FIG. 27 is a timing chart showing a current and a target current when the current control device of FIG. 26 detects excessive vibration,

FIG. 28 is a flowchart for explaining a process executed by the current control device of FIG. 26,

fig. 29 is a timing chart illustrating a mechanism of generating self-excited vibration of the spool valve by taking a comparative example.

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 (hereinafter, 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 sets the duty ratio of the drive signal so that the actual current of the solenoid 44 follows the target current, that is, so that the difference between the actual current and the target current becomes small, and generates and outputs the drive signal. 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 a 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 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. 29, 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 affected by this 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. 29 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. 29, the spool oscillates as self-excited oscillation.

When excessive vibration such as self-excited vibration or coupled vibration occurs in the solenoid valve 31, the output hydraulic pressure largely pulsates, and controllability is degraded. Therefore, it is important to detect the generation of excessive vibration and implement countermeasures. Conventionally, this determination is performed based on a detection value of a hydraulic pressure sensor. However, providing the hydraulic pressure sensor is not preferable because it increases the size, weight, and cost of the hydraulic circuit.

Therefore, whether or not excessive vibration can be detected without using a hydraulic pressure sensor has been studied, and the following has been found. Fig. 12 to 14 show the relationship between the stroke slope and the actual current change amount Δ I when the duty change amount Δ D is within a predetermined range (-D ± e%), for the stabilization period, the excessive vibration transition period, and the excessive vibration generation period, respectively. The duty change amount Δ D is a change amount of the duty D over a predetermined time period, and is, for example, a change amount of the duty D from a time t1 to a time t2 when the predetermined time period elapses, when the time t1 is taken as a reference in fig. 15. The actual current change amount Δ I is a change amount of the actual current over a predetermined time, and is, for example, a change amount of the average actual current during a period from time t1 to time t2 when the predetermined time has elapsed in fig. 15. The predetermined time is set to a period shorter than the PWM period Tpwm, for example. The average actual current is, for example, an average of actual currents in a period shorter than the PWM period Tpwm.

In the stable period of fig. 12, the positional relationship between the stroke slope and the actual current variation Δ I with respect to the duty ratio D is substantially concentrated in one place, and the deviation is small.

On the other hand, in the excessive vibration transfer period of fig. 13, the actual amount of current change Δ I with respect to the duty ratio D differs according to the stroke slope. In the case where the stroke slope is biased to the + side, the actual amount of current change Δ I is relatively small. In the case where the stroke slope is biased to the minus side, the actual amount of current variation Δ I is relatively large. Here, there is a region where the direction of the actual current change amount Δ I with respect to the duty ratio D is reversed.

In the excessive vibration generating period of fig. 14, the positional relationship of the stroke slope with respect to the duty ratio D and the actual current variation Δ I shows the same tendency as the excessive vibration transfer period. However, since the stroke slope increases due to excessive vibration, the actual current change amount Δ I is also large.

As described above, in the excessive vibration generating period and the excessive vibration transition period, the actual current of the solenoid 44 shows a behavior different from that in the stationary period. This is considered to be because, when the pulsation of the output hydraulic pressure increases due to vibration, the phase of the stroke change of the spool becomes slower than when the pulsation of the output hydraulic pressure is small, and the inductance of the solenoid differs. Therefore, even if the duty ratio of the drive signal is set in the same manner as when the pulsation of the output hydraulic pressure is small, the current actually flowing through the solenoid differs.

The current control device 13 includes: a vibration determination unit 66 for determining whether excessive vibration such as self-excited vibration and coupled vibration has occurred or whether excessive vibration has been transferred; and a target setting unit 64 for suppressing generation of excessive vibration.

(function part of Current control device)

Next, the vibration determination unit 66 and 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 period (i.e., PWM period Tpwm). The vibration determination unit 66 determines, based on the behavior of the actual current, whether or not excessive vibration has occurred or has shifted to excessive vibration, as compared to the micro-vibration that is generated by applying the dither amplitude Ad to the target current Ir. Target setting unit 64 sets dither amplitude Ad of target current Ir based on the determination result of dither determination unit 66.

Specifically, the vibration determination unit 66 includes an average actual current calculation unit 71, a first change amount calculation unit 72, a second change amount calculation unit 73, a first determination unit 74, and a second determination unit 75. The average actual current calculation unit 71 calculates an average actual current Iav which is an average value of actual currents in a certain period.

The first variation calculating section 72 calculates the actual current variation Δ I. The actual current change amount Δ I is a change amount of the average actual current Iav during a period from when the duty ratio D is changed until a predetermined time elapses. When the average actual current Iav before the duty ratio is changed is Iav1 and the average actual current Iav when a predetermined time has elapsed after the duty ratio is changed is Iav2, the actual current change amount Δ I is Iav1 to Iav 2.

The second variation calculating section 73 calculates the duty ratio variation Δ D. The duty ratio change amount Δ D is the change amount of the duty ratio D until a predetermined time elapses after the duty ratio D is changed. That is, the duty ratio change amount Δ D is the difference between the duty ratio D1 before the change and the duty ratio D2 after the change.

When the absolute value of the actual current change amount Δ I is equal to or greater than the predetermined first threshold value Th1 and the absolute value of the duty change amount Δ D is equal to or greater than the predetermined second threshold value Th2, the first determination unit 74 allows the second determination unit 75 to execute the operation. That is, the first judgment unit 74 permits the execution of the second judgment unit 75 when "Δ I ≧ Th 1", or "-Th 1 ≧ Δ I", and "Δ D ≧ Th 2", or "-Th 2 ≧ Δ D". The first threshold value Th1 is a value that is set in advance to exclude a value that causes erroneous determination (i.e., a value close to zero) when determining the trend of the direction of change of the actual current change amount Δ I, and is set to, for example, half or half the maximum design value of the actual current change amount Δ I. However, the present invention is not limited to this, and the first threshold value Th1 may be set to other values. The second threshold value Th2 is a value set in advance to exclude a value (i.e., a value close to zero) that causes an erroneous determination when determining the tendency of the direction of change of the duty ratio change amount Δ D, and is set to, for example, one-half or two-thirds of the maximum design value of the duty ratio change amount Δ D. However, the present invention is not limited to this, and the second threshold value Th2 may be set to other values.

When the direction of change of the actual current change amount Δ I and the direction of change of the duty change amount Δ D are different, the second determination unit 75 determines that excessive vibration has occurred or has shifted to excessive vibration. For example, when the product of the actual current change amount Δ I and the duty ratio change amount Δ D is smaller than zero, it is determined that the two change directions are different.

The target setting unit 64 includes an average target calculation unit 76 and an amplitude calculation unit 77. The average target calculation portion 76 calculates the average target current Irav based on the target output hydraulic pressure Pr. For example, 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.

When the determination by the second determination unit 75 is negative (that is, when excessive vibration is not generated and excessive vibration is not transferred), the amplitude calculation unit 77 calculates the first dither amplitude Ad1 based on at least the average target current Irav and determines the first dither amplitude Ad1 as the dither amplitude Ad. In the first embodiment, the amplitude calculation section 77 calculates the first dither amplitude Ad1 based on the average target current Irav and the oil temperature To. In addition, when the determination by the second determination unit 75 is positive (that is, when an excessive vibration is generated or has shifted to an excessive vibration), the amplitude calculation unit 77 determines the second dither amplitude Ad2, which is smaller than the first dither amplitude Ad1, as the dither amplitude Ad.

As described above, the vibration determination unit 66 determines whether or not excessive vibration has occurred in the solenoid valve 31 or whether or not excessive vibration has shifted to it, based on the behavior of the actual current. As shown in FIG. 16, at times t11 and t15 "Δ D ≧ Th 2", the Δ D detection flag is set to 1. At time t14 when "-Th 2 ≧ Δ D", the Δ D detection flag is set to 2. At time t11 when "Δ I ≧ Th 1", the Δ I detection flag is set to 1. At times t13 and t15 when "-Th 1 ≧ Δ I", the Δ I detection flag is set to 2. Then, the second determination unit 75 is caused to execute at times t11, t15 when the Δ D detection flag is 1 or 2 and the Δ I detection flag is 1 or 2. Then, at t15 where the two flags have different values, the abnormality detection flag is turned on, and it is determined that excessive vibration has occurred or has shifted to excessive vibration.

When the abnormality is detected in this way, as shown in fig. 17, 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 pressure 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.

The functional units 64 to 66, 71 to 78 of the current control device 13 may be realized by hardware processing based on a dedicated logic circuit, by software processing based on 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 66, 71 to 78 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 determine the presence or absence of excessive vibration and to set a target current will be described with reference to fig. 19. The routine shown in fig. 19 is repeatedly executed every time a predetermined time elapses after the duty ratio is changed. Hereinafter, "S" denotes a step.

In S1 of fig. 19, the average target current Irav is calculated. After S1, the process moves to S2.

In S2, an average actual current Iav is calculated. After S2, the process moves to S3.

In S3, the amount of change in the average actual current Iav from when the duty ratio is changed to when the predetermined time has elapsed is calculated as the actual current change amount Δ I. That is, the actual current variation Δ I is the difference between the previous average actual current Iav1 and the present average actual current Iav 2. After S3, the process moves to S4.

At S4, it is determined whether or not the absolute value of the actual current change amount Δ I is equal to or greater than a predetermined first threshold value Th 1. That is, it is determined whether "Δ I ≧ Th 1" or "-Th 1 ≧ Δ I". If "Δ I.gtoreq.Th 1" or "-Th 1.gtoreq.Δ I" (S4: YES), the process proceeds to S5. If "Δ I.gtoreq.Th 1" or "-Th 1.gtoreq.Δ I" (S4: No), the process proceeds to S8.

In S5, the difference between the duty ratio before the change and the duty ratio after the change is calculated as the duty ratio change amount Δ D. That is, the duty change amount Δ D is the difference between the duty D1 in the previous routine and the current duty D2. After S5, the process moves to S6.

At S6, it is determined whether or not the absolute value of the duty change amount Δ D is equal to or greater than a predetermined second threshold value Th 2. That is, it is determined whether "Δ D ≧ Th 2" or "-Th 2 ≧ Δ D". If "Δ D.gtoreq.Th 2" or "-Th 2. gtoreq.Δ D" (S6: YES), the process proceeds to S7. If "Δ D.gtoreq.Th 2" or "-Th 2.gtoreq.Δ D" (S6: No), the process proceeds to S8.

At S7, it is determined whether or not the direction of change of the actual current change amount Δ I is different from the direction of change of the duty change amount Δ D. That is, it is determined whether or not "Δ I × Δ D < 0". If "Δ I × Δ D < 0" (S7: YES), the process proceeds to S9. If not (S7: NO), the process proceeds to S8.

At S8, a first dither amplitude Ad1 is calculated based on the average target current Irav and the oil temperature To, and this first dither amplitude Ad1 is determined as the dither amplitude Ad. After S8, the process moves to S10.

In S9, the second dither amplitude Ad2 smaller than the first dither amplitude Ad1 is calculated, and this second dither amplitude Ad2 is determined as the dither amplitude Ad. After S9, the process moves to S10.

In S10, the target current Ir is set based on the average target current Irav, the dither amplitude Ad, and the dither period Td. The dither period Td is a predetermined value. After S10, the process exits the routine of fig. 19.

(Effect)

As described above, in the first embodiment, the current control device 13 is applied to the solenoid valves 31 to 36 having a self-pressure-adjusting function based on the feedback force corresponding to the output hydraulic pressure.

The current control device 13 includes: a current detection unit 63 for detecting the actual current of the solenoid 44; a drive circuit 62 that energizes the solenoid 44 with a PWM period Tpwm in accordance with a drive signal; a signal output unit 65 that sets a duty ratio D of the drive signal so that the actual current follows the target current Ir, and generates and outputs the drive signal; 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 longer than the PWM period Tpwm. The current control device 13 further includes a vibration determination unit 66, and the vibration determination unit 66 determines whether or not an excessive vibration is generated or has shifted to an excessive vibration, based on the behavior of the actual current, as compared with the micro-vibration generated by applying the dither amplitude Ad to the target current Ir.

By performing the determination based on the behavior of the actual current in this way, it is possible to detect the occurrence of excessive vibration of the solenoid valves 31 to 36 without the need for a hydraulic sensor.

In the first embodiment, when the absolute value of the change amount Δ I of the actual current over the predetermined time is equal to or greater than the first threshold value Th1 and the absolute value of the change amount Δ D of the duty ratio D over the predetermined time is equal to or greater than the second threshold value Th2, the vibration determination unit 66 determines whether or not excessive vibration has occurred or has shifted to excessive vibration, based on the behavior of the actual current. This can prevent erroneous detection.

In the first embodiment, when the direction of change of the actual current over the predetermined time is different from the direction of change of the duty ratio over the predetermined time, the vibration determination unit 66 determines that excessive vibration has occurred or has shifted to excessive vibration. Thus, the occurrence of excessive vibration of the solenoid valves 31 to 36 can be detected.

In the first embodiment, when it is determined that excessive vibration has occurred or has shifted to excessive vibration, the target setting unit 64 reduces the dither amplitude Ad as compared with the case where the determination is negative. By thus reducing the dither amplitude Ad, the force balance of the spool valve 42 is not significantly disrupted. Therefore, the occurrence of vibration of the solenoid valves 31 to 36 can be suppressed.

[ second embodiment ]

In the second embodiment, as shown in fig. 20, the vibration determination unit 86 of the current control device 83 includes the average actual current calculation unit 71, the first change amount calculation unit 72, the second change amount calculation unit 73, and the determination unit 84. When the change amount Δ I of the actual current over the predetermined time is not within the design value range (Δ Id ± α) determined based on the change amount Δ D of the duty D over the predetermined time, the determination unit 84 determines that excessive vibration has occurred or has shifted to excessive vibration. The design value range is a range in which the design value Δ Id of the actual current variation has a width from + a predetermined value α to-a predetermined value α at the center. The design value range (Δ Id ± α) is set to a width of a degree that the sign of the actual current change amount Δ I is not inverted, for example.

(processing performed by Current control means)

Next, with reference to fig. 21, a process executed by the current control device 83 to determine the presence or absence of excessive vibration and to set a target current will be described. The routine shown in fig. 21 is repeatedly executed every time a predetermined time elapses after the duty ratio is changed.

In S11 to S14 and S17 to S19 in fig. 22, the same processing as in S1 to S4 and S8 to S10 in fig. 19 in the first embodiment is performed.

In S15, the design value range (Δ Id ± α) of the actual current variation amount is calculated based on the duty variation amount Δ D. After S15, the process moves to S16.

In S16, it is determined whether or not the actual current change amount Δ I is within the design value range (Δ Id ± α). When the actual current change amount Δ I is within the design value range (Δ Id ± α) (S16: yes), the process proceeds to S17. If the actual current change amount Δ I is not within the design value range (Δ Id ± α) (S16: no), the process proceeds to S18.

(Effect)

As described above, in the second embodiment, the current control device 83 includes the vibration determination unit 86, and the vibration determination unit 86 determines whether or not the excessive vibration is generated or whether or not the excessive vibration has shifted to the excessive vibration, based on the behavior of the actual current. Therefore, as in the first embodiment, the occurrence of excessive vibration of the solenoid valves 31 to 36 can be detected without the need for a hydraulic pressure sensor.

In the second embodiment, when the actual current change amount Δ I is not within the design value range (Δ Id ± α) determined according to the duty change amount Δ D, the determination unit 84 of the vibration determination unit 86 determines that excessive vibration has occurred or has shifted to excessive vibration. Thus, the occurrence of excessive vibration of the solenoid valves 31 to 36 can be detected.

[ third embodiment ]

In the third embodiment, as shown in fig. 22, the target setting unit 94 of the current control device 93 includes an average target calculation unit 76 and a cycle calculation unit 97. When the determination by the second determination unit 75 is negative (that is, when excessive vibration is not generated and excessive vibration is not transferred), the cycle calculation unit 97 determines the predetermined first cycle T1 as the dither cycle Td. When the determination by the second determination unit 75 is affirmative (that is, when excessive vibration occurs or has shifted to excessive vibration), the period calculation unit 97 determines a predetermined second period T2, which is longer than the first period T1, 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.

In this way, when excessive vibration occurs or has shifted to excessive vibration, as shown in fig. 23, a second dither period Td2 having a relatively long dither period is set. 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 t31 to t32 and t33 to t34 in fig. 24, a time until the force balance is restored can be ensured. Therefore, the stable states at times t32 to t33 and t34 to t35 in fig. 24 can be ensured.

(processing performed by Current control means)

Next, with reference to fig. 25, a process executed by the current control device 83 to determine the presence or absence of excessive vibration and to set a target current will be described. The routine shown in fig. 25 is repeatedly executed every time a predetermined time elapses after the duty ratio is changed.

In S21 to S27 and S30 of fig. 25, the same processing as in S1 to S7 and S10 of fig. 19 of the first embodiment is performed.

In S28, a predetermined first period T1 is determined as a dither period Td. After S28, the process moves to S30.

In S29, a predetermined second period T2 longer than the first period T1 is determined as a dither period Td. After S28, the process moves to S30.

(Effect)

As described above, in the third embodiment, since the current control device 93 includes the vibration determination unit 66, the occurrence of excessive vibration of the solenoid valves 31 to 36 can be detected without the need for the hydraulic pressure sensor, as in the first embodiment.

In the third embodiment, when it is determined that excessive vibration has occurred or has shifted to excessive vibration, the target setting unit 94 extends the dither cycle Td more than when the determination is negative. 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 occurrence of vibration of the solenoid valves 31 to 36 can be suppressed.

[ fourth embodiment ]

In the fourth embodiment, as shown in fig. 26, the target setting unit 104 of the current control device 103 includes an average target calculation unit 106 and an amplitude calculation unit 107. The average target calculation portion 106 calculates the average target current Irav based on the target output hydraulic pressure Pr. In addition, when the determination by the second determination unit 75 is affirmative (that is, when excessive vibration occurs or has shifted to excessive vibration), the average target calculation unit 106 sets the average target current Irav to zero. When the determination in the second determination unit 75 is affirmative, the amplitude calculation unit 107 sets the dither amplitude Ad to zero. That is, when the determination by the second determination unit 75 is positive, the target setting unit 104 sets the target current Ir to zero. The target current Ir continues for a predetermined period of time to the extent that voltage regulation is not hindered.

In this way, when excessive vibration occurs or has been transferred to excessive vibration, the electromagnetic force in the vibration energy can be cut off by setting the target current Ir to zero as shown in fig. 27, and thus the oscillation can be cut off.

(processing performed by Current control means)

Next, with reference to fig. 28, a process executed by the current control device 103 to determine the presence or absence of excessive vibration and to set a target current will be described. The routine shown in fig. 28 is repeatedly executed every time a predetermined time elapses after the duty ratio is changed.

In S31 to S38 and S41 of fig. 28, the same processing as in S1 to S7 and S10 of fig. 19 of the first embodiment is performed.

In S39, the average target current Irav is set to zero. After S39, the process moves to S40.

In S40, dither amplitude Ad is set to zero. After S40, the process moves to S41.

(Effect)

As described above, in the fourth embodiment, since the current control device 103 includes the vibration determination unit 66, the occurrence of excessive vibration of the solenoid valves 31 to 36 can be detected without the need for the hydraulic pressure sensor, as in the first embodiment.

In the fourth embodiment, when it is determined that excessive vibration has occurred or has shifted to excessive vibration, the target setting unit 104 sets the target current Ir to zero. By setting the target current Ir to zero in this way, the electromagnetic force in the vibration energy can be cut off, and therefore, oscillation can be interrupted. Therefore, the occurrence of vibration of the solenoid valves 31 to 36 can be suppressed.

[ other embodiments ]

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.