JP7523745B2 - Hydraulic Control Device - Google Patents

Description

The present invention relates to a hydraulic control device, and in particular to a hydraulic control device for an automatic transmission that performs gear changes by switching between engagement and disengagement of multiple frictional engagement elements.

Patent Publication No. 5761337 (Patent Document 1) describes a method and device for controlling an automatic transmission, and an automatic transmission system. The automatic transmission described therein is equipped with a plurality of frictional engagement elements, and is configured so that the gear stage can be changed by selectively engaging these frictional engagement elements to change the power transmission path within the automatic transmission. In other words, when changing the gear stage of the automatic transmission from one gear stage to another, some of the frictional engagement elements that were engaged are released, and other frictional engagement elements that were released are engaged, thereby changing the power transmission path within the automatic transmission.

In addition, generally, when an automatic transmission is shifting, a solenoid valve provided corresponding to a frictional engagement element to be engaged is operated, and this solenoid valve moves a spool to supply hydraulic pressure to the frictional engagement element to engage it. Also, a solenoid valve provided corresponding to a frictional engagement element to be released (disengaged) is operated to stop the supply of hydraulic pressure to the frictional engagement element and release it. When the vehicle starts moving, the frictional engagement elements that constitute the gear stages when the automatic transmission starts, such as first gear and reverse, are engaged to start the vehicle. In the automatic transmission described in Patent Document 1, a precharge is performed so that the timing of the operation of the solenoid valves provided corresponding to the frictional engagement elements to be engaged and the frictional engagement elements to be released is accurately aligned when the vehicle starts moving or when the gears are changed.

Patent No. 5761337

However, the spool, which is moved by the solenoid valve provided for each frictional engagement element to switch the automatic transmission, may become stuck and become difficult to move. If the spool becomes stuck in this way, it takes a long time for the solenoid valve to be activated and the spool to actually move after a control signal is sent to the solenoid valve, and it takes a long time for hydraulic pressure to actually be supplied to the frictional engagement element to be engaged. If the spool becomes stuck in this way, even if pre-charging is performed as in the invention described in Patent Document 1, the engagement of the frictional engagement element is delayed, and the response of the automatic transmission to shift gears becomes poor. In addition, if the spool is stuck when the vehicle starts, there is a problem that the driver cannot start smoothly when he or she intends.

The present invention therefore aims to provide a hydraulic control device for an automatic transmission that can suppress delays in vehicle start caused by delays in hydraulic supply.

In order to solve the above-mentioned problems, the present invention provides a hydraulic control device for an automatic transmission which performs gear changes by switching between engagement and non-engagement of a plurality of frictional engagement elements, the hydraulic control valve including a hydraulic pump, a flow control valve which adjusts the flow rate of hydraulic oil supplied from the hydraulic pump, an engagement hydraulic control valve provided corresponding to each of the frictional engagement elements and which switches between engagement and non-engagement of each of the frictional engagement elements by switching between supplying and non-supplying hydraulic oil to each of the frictional engagement elements from the flow control valve, and a control device which switches between supplying and non-supplying hydraulic oil to each of the frictional engagement elements by supplying a predetermined control current to these engagement hydraulic control valves, the engagement hydraulic control valve including a solenoid valve to which a control current is supplied from the control device, a spool driven by the solenoid valve, a cylinder in which the spool slides, and a clutch mechanism provided between a closed end of the cylinder and the tip of the spool. and a biasing spring positioned at the end of the spool, the spool having, in that order from its tip, a first large diameter portion, a small diameter portion, and a second large diameter portion, the cylinder having a first port connected to the flow control valve, a second port located closer to the solenoid valve than the first port and connected to a frictional fastening element to which hydraulic pressure is to be supplied, and a third port located closer to the solenoid valve than the second port, closeable by the second large diameter portion, and allowing hydraulic oil in the cylinder to flow out, the first port being located closer to the closed end of the cylinder than the second large diameter portion of the spool when the solenoid valve is not energized, and the control device is configured to supply a single pulse-shaped anti-stick current to an engagement hydraulic control valve provided corresponding to one of the frictional fastening elements that is to be engaged when the vehicle starts, after the engine of a vehicle equipped with an automatic transmission is started and before the vehicle starts.

In the present invention configured in this manner, the control device supplies a predetermined control current to the solenoid valve. The solenoid valve is provided for each frictional engagement element of the automatic transmission, and switches between engagement and non-engagement of each frictional engagement element based on the control current of the control device by switching between supplying and not supplying hydraulic pressure to each frictional engagement element. In addition, after the vehicle engine starts and before starting, the control device supplies an anti-sticking current to the solenoid valve provided for each frictional engagement element that is engaged at the time of starting.

The inventor has found that the delay in supplying hydraulic pressure to the frictional engagement element to be engaged is caused by the sticking of the parts driven by the solenoid valve, and that the occurrence of this sticking can be suppressed by supplying a sticking prevention current to the solenoid valve. That is, the inventor has found that if the frictional engagement elements provided in the automatic transmission are left in a non-engaged state for a long period of time when the vehicle is parked or stopped, this causes the element to stick. According to the present invention configured as described above, after the engine of the vehicle is started and before the vehicle starts, the control device supplies a sticking prevention current to the solenoid valve provided corresponding to the frictional engagement element that is to be engaged at the time of starting, among the respective frictional engagement elements, a sticking prevention current is supplied, thereby suppressing the occurrence of sticking. That is, by supplying a sticking prevention current to the solenoid valve, the sticking of the parts driven by the solenoid valve is eliminated, and the vehicle can be started smoothly when the driver performs the start operation. After the vehicle engine starts, the hydraulic pump is operating, so when an anti-stick current is supplied to the solenoid valve, the frictional engagement element provided for that solenoid valve is engaged. However, because the anti-stick current is supplied before the vehicle starts, the engagement of the frictional engagement element does not cause the vehicle to start.

In the present invention, the anti-sticking current supplied after the engine of the vehicle is started and before the vehicle starts moving is preferably set to a current lower than the control current.
According to the present invention configured in this manner, the anti-stick current supplied after the engine is started and before the vehicle starts is set to a current lower than the control current, so that power consumption due to the supply of the anti-stick current can be reduced, and the occurrence of sticking can be suppressed with low power consumption.

In the present invention, preferably, at least one of the solenoid valves is configured so that the corresponding frictional fastening element is switched to the fastened state when a control current is supplied.

According to the present invention configured in this manner, when a control current is supplied to at least one solenoid valve, hydraulic pressure is supplied to the corresponding frictional fastening element, and the solenoid valve is put into an engaged state, so that the solenoid valve can be put into an unfastened state without passing a current through it, thereby reducing current consumption. In addition, the anti-sticking current that is supplied after the engine starts and before the vehicle starts only needs to be a very small current, so the amount of current consumed to prevent sticking can be further reduced.

The present invention also provides a hydraulic control device for an automatic transmission that performs gear changes by switching between engagement and non-engagement of a plurality of frictional engagement elements, the hydraulic control valve being provided for each frictional engagement element and switching between engagement and non-engagement of each frictional engagement element by switching between supplying and non-supplying hydraulic pressure to each frictional engagement element, and a control device that switches between supplying and non-supplying hydraulic pressure to each frictional engagement element by supplying a predetermined control current to these engagement hydraulic control valves, the control device being configured to supply an anti-stick current to an engagement hydraulic control valve provided corresponding to one of the frictional engagement elements that is engaged when the vehicle is started after the engine of a vehicle equipped with the automatic transmission is started and before the vehicle is started, at least one of the plurality of frictional engagement elements is a zero-touch clutch in which the clearance between friction plates that constitute the frictional engagement element is substantially zero, and when the vehicle equipped with the automatic transmission is started, the plurality of frictional engagement elements including the zero-touch clutch are engaged, and the control device being configured to supply an anti-stick current only to a solenoid valve provided corresponding to the zero-touch clutch.

Since the zero-touch clutch has essentially zero clearance between the friction plates, using it as a frictional fastening element for starting the vehicle can improve the responsiveness of the vehicle when starting. Furthermore, according to the present invention configured as described above, before the vehicle starts, a sticking prevention current is supplied only to the solenoid valve provided for the zero-touch clutch, so that it is possible to reliably prevent the vehicle from starting due to the supply of a sticking prevention current.

In the present invention, the control device preferably stops the supply of anti-sticking current to the zero-touch clutch, and then engages frictional engagement elements other than the zero-touch clutch that are engaged when the vehicle equipped with the automatic transmission starts.

According to the present invention configured in this way, after the supply of anti-sticking current to the zero-touch clutch is stopped, frictional fastening elements other than the zero-touch clutch that is engaged when starting are engaged. Therefore, when starting the vehicle, the vehicle can be started simply by supplying a control current to the solenoid valve provided corresponding to the zero-touch clutch, making it possible to achieve extremely good responsiveness when starting the vehicle.

The hydraulic control device for an automatic transmission of the present invention can suppress delays in vehicle start caused by delays in hydraulic supply.

1 is a block diagram showing an entire automatic transmission system equipped with a hydraulic control device according to an embodiment of the present invention. 1 is a diagram showing a schematic configuration of an automatic transmission in which gear positions are changed by a hydraulic control device according to an embodiment of the present invention; 4 is a clutch/brake-gear position correspondence table for an automatic transmission in which gear positions are changed by a hydraulic control device according to an embodiment of the present invention. 1 is a diagram showing a hydraulic control circuit provided in a hydraulic control device according to an embodiment of the present invention. 2 is a cross-sectional view of a fastening hydraulic control valve in an energized state in the hydraulic control device according to the embodiment of the present invention. FIG. 2 is a cross-sectional view of a fastening hydraulic control valve in a non-energized state in the hydraulic control device according to the embodiment of the present invention. FIG. 5 is a graph showing an example of the action of the fastening hydraulic control valve when sticking occurs. FIG. 4 is a diagram showing an example of a waveform of a sticking prevention current supplied to a coil of a fastening hydraulic control valve in the hydraulic control device according to the embodiment of the present invention. 4 is a graph showing the relationship between the current supplied to an engagement hydraulic control valve and the hydraulic pressure supplied to a frictional engagement element provided corresponding thereto in the hydraulic control device according to the embodiment of the present invention. 4 is a flowchart showing a process executed by a control device of an ECU in the hydraulic control device according to the embodiment of the present invention.

Next, a hydraulic control device for an automatic transmission according to an embodiment of the present invention will be described with reference to the accompanying drawings.
Fig. 1 is a block diagram showing an entire automatic transmission system equipped with a hydraulic control device according to an embodiment of the present invention. Fig. 2 is a diagram showing a schematic configuration of an automatic transmission in which gears are shifted by a hydraulic control device according to an embodiment of the present invention. Fig. 3 is a clutch/brake-gear correspondence table in an automatic transmission in which gears are shifted by a hydraulic control device according to an embodiment of the present invention. Fig. 4 is a diagram showing a hydraulic control circuit provided in the hydraulic control device according to an embodiment of the present invention.

As shown in FIG. 1, an automatic transmission system 1 equipped with a hydraulic control device according to an embodiment of the present invention has a vehicle speed sensor 2, a throttle opening sensor 4, a turbine speed sensor 6, an ATF water temperature sensor 8, and an engagement hydraulic sensor 10. Furthermore, the automatic transmission system 1 has an ECU 12 to which signals from the above sensors are input, a hydraulic control circuit 14 controlled by a control signal from the ECU 12, and an automatic transmission 20 in which the gears are changed by the hydraulic pressure supplied from the hydraulic control circuit 14.

The vehicle speed sensor 2 is configured to detect the vehicle speed of a vehicle (not shown) in which the automatic transmission system 1 is mounted, and input a detection signal to the ECU 12 .
The throttle opening sensor 4 is configured to detect the throttle opening of an engine (not shown) of a vehicle (not shown) in which the automatic transmission system 1 is mounted, and input a detection signal to the ECU 12 .
The turbine speed sensor 6 is configured to detect the rotation speed of a turbine of a turbocharger (not shown) provided in the engine of a vehicle in which the automatic transmission system 1 is installed, and input a detection signal to the ECU 12.

The ATF water temperature sensor 8 is configured to detect the temperature of hydraulic oil (automatic transmission fluid) supplied to the automatic transmission 20 and input a detection signal to the ECU 12 .
The engagement hydraulic pressure sensor 10 is configured to detect the temperature of hydraulic oil supplied to each frictional engagement element 22 of the automatic transmission 20 via the hydraulic control circuit 14, and input a detection signal to the ECU 12. As will be described later, the automatic transmission 20 is equipped with a plurality of frictional engagement elements 22, and a plurality of engagement hydraulic pressure sensors 10 are provided corresponding to each of these frictional engagement elements 22. The pressure of the hydraulic oil supplied to each frictional engagement element 22 is detected by the engagement hydraulic pressure sensor 10 provided corresponding to each frictional engagement element 22, and a detection signal is input to the ECU 12.

The ECU (Electric Control Unit) 12 is configured to control the vehicle engine (not shown), the automatic transmission 20, etc., based on the detection signals input from each sensor. Specifically, the ECU 12 is configured to calculate an appropriate gear shift stage of the automatic transmission 20 based on the detection signals detected by the vehicle speed sensor 2, the throttle opening sensor 4, and the turbine speed sensor 6, and to control the automatic transmission 20 based on this. That is, when the ECU 12 calculates an appropriate gear shift stage, it switches between engagement and non-engagement of the first to fifth frictional engagement elements 22a to 22e provided in the automatic transmission 20 so that the gear shift stage is realized. In addition, the engagement and non-engagement of the first to fifth frictional engagement elements 22a to 22e are switched by supplying and not supplying hydraulic pressure to the frictional engagement elements. Therefore, the ECU 12 switches between engagement and non-engagement of the first to fifth frictional engagement elements 22a to 22e by controlling the first to fifth engagement hydraulic control valves 16a to 16e and the flow control valve 18 provided in the hydraulic control circuit 14.

That is, the first to fifth engagement hydraulic control valves 16a to 16e are provided corresponding to the first to fifth frictional engagement elements 22a to 22e provided in the automatic transmission 20, respectively, and the ECU 12 switches between engagement and non-engagement by controlling the engagement hydraulic control valve corresponding to the frictional engagement element to be switched. In the following, the first to fifth engagement hydraulic control valves 16a to 16e are collectively referred to simply as the engagement hydraulic control valve 16, and the first to fifth frictional engagement elements 22a to 22e are collectively referred to simply as the frictional engagement elements 22. Here, the ECU 12 is composed of a microprocessor, various interface circuits, memory, software for operating these (all not shown), etc. Some circuits of the ECU 12 configured in this manner function as a control device 12a that switches between supplying and non-supplying hydraulic pressure to each frictional engagement element 22 by supplying a predetermined control current to the solenoid valve of each engagement hydraulic control valve 16. In addition, the solenoid valves provided in each fastening hydraulic control valve 16 and the control device 12a function as a hydraulic control device according to an embodiment of the present invention. Note that the control device 12a may be configured with hardware separate from the ECU 12 for controlling the vehicle engine (not shown) and the like.

Next, the configuration of an automatic transmission in which gear positions are changed by the hydraulic control device according to the embodiment of the present invention will be described with reference to Figs.
In this embodiment, the automatic transmission 20 is a longitudinally mounted automatic transmission mounted on a vehicle such as an FR vehicle. As shown in FIG. 2, the automatic transmission 20 includes a transmission case 20a, an input shaft 20b inserted into the transmission case 20a from the drive source of the vehicle (left side of the figure), and an output shaft 20c protruding from the inside of the transmission case 20a to the opposite drive source side (right side of the figure). The input shaft 20b and the output shaft 20c are arranged on the same axis along the vehicle front-rear direction, and the automatic transmission 20 is arranged in a longitudinally mounted position with the input shaft 20b located on the front side of the vehicle and the output shaft 20c located on the rear side of the vehicle. For this reason, hereinafter, the drive source side (left side of the figure) may be referred to as the front side, and the opposite drive source side (right side of the figure) may be referred to as the rear side.

A first, second, third and fourth planetary gear set (hereinafter simply referred to as "gear set") PG1, PG2, PG3 and PG4 are arranged on the axis of the input shaft 20b and the output shaft 20c in this order from the front side (drive source side).

In the transmission case 20a, the first clutch CL1 is disposed in front of the first gear set PG1, the second clutch CL2 is disposed in front of the first clutch CL1, and the third clutch CL3 is disposed in front of the second clutch CL2. The first brake BR1 is disposed in front of the third clutch CL3, and the second brake BR2 is disposed radially outside the third gear set PG3. In this way, the frictional engagement elements of the automatic transmission 20 (the first to third clutches CL1 to CL3 and the first and second brakes BR1 and BR2) are disposed axially in the following order from the front side (drive source side): the first brake BR1, the third clutch CL3, the second clutch CL2, the first clutch CL1, and the second brake BR2.

The first to fourth gear sets PG1 to PG4 are all single pinion types in which a pinion supported by a carrier directly meshes with a sun gear and a ring gear. The first gear set PG1 has a first sun gear S1, a first ring gear R1, and a first carrier C1 as rotating elements. The second gear set PG2 has a second sun gear S2, a second ring gear R2, and a second carrier C2 as rotating elements. The third gear set PG3 has a third sun gear S3, a third ring gear R3, and a third carrier C3 as rotating elements. The fourth gear set PG4 has a fourth sun gear S4, a fourth ring gear R4, and a fourth carrier C4 as rotating elements.

The first gear set PG1 is a double sun gear type in which the first sun gear S1 is divided into two in the axial direction. That is, the first sun gear S1 has a front first sun gear S1a arranged on the axial front side and a rear first sun gear S1b arranged on the axial rear side. The pair of first sun gears S1a, S1b have the same number of teeth and mesh with the same pinion supported by the first carrier C1, so the rotation speeds of the first sun gears S1a, S1b are always equal. In other words, the pair of front and rear first sun gears S1a, S1b always rotate at the same speed, and when the rotation of one is stopped, the rotation of the other is also stopped.

In this automatic transmission 20, the first sun gear S1 (more specifically, the rear first sun gear S1b) and the fourth sun gear S4 are always connected, the first ring gear R1 and the second sun gear S2 are always connected, the second carrier C2 and the fourth carrier C4 are always connected, and the third carrier C3 and the fourth ring gear R4 are always connected. The input shaft 20b is always connected to the first carrier C1, and the output shaft 20c is always connected to the fourth carrier C4. Specifically, the input shaft 20b is connected to the first carrier C1 via a power transmission member 24a that passes between the pair of front and rear first sun gears S1a, S1b. The rear first sun gear S1b and the fourth sun gear S4 are connected to each other via a power transmission member 24b. The fourth carrier C4 and the second carrier C2 are connected to each other via a power transmission member 24c.

The first clutch CL1 connects and disconnects the input shaft 20b and the first carrier C1 to and from the third sun gear S3. The second clutch CL2 connects and disconnects the first ring gear R1 and the second sun gear S2 to and from the third sun gear S3. The third clutch CL3 connects and disconnects the second ring gear R2 to and from the third sun gear S3.

Specifically, the first clutch CL1 has a rotatable inner holding member connected to the first carrier C1, a hub side friction plate engaged with the outer peripheral surface of the inner holding member, a rotatable outer holding member connected to the third sun gear S3 via the power transmission members 24d and 24e, a drum side friction plate engaged with the inner peripheral surface of the outer holding member, and a piston P1 that is driven forward and backward in the axial direction to press the hub side friction plate and the drum side friction plate together. A hydraulic chamber F1 into which hydraulic pressure supplied from the hydraulic control circuit 14 is introduced is defined adjacent to the piston P1, and the hub side friction plate and the drum side friction plate are pressed together or released from the pressurization in response to the supply and discharge of hydraulic pressure to the hydraulic chamber F1. The inner holding member and the outer holding member are connected to or separated from each other by the pressing or releasing, and the input shaft 20b and the first carrier C1 are connected to and disconnected from the third sun gear S3.

The second clutch CL2 has a rotatable inner holding member connected to the third sun gear S3 via power transmission members 24d and 24e, a hub side friction plate engaged with the outer circumferential surface of the inner holding member, a rotatable outer holding member connected to the first ring gear R1 and the second sun gear S2 via power transmission member 24f, a drum side friction plate engaged with the inner circumferential surface of the outer holding member, and a piston P2 that is driven forward and backward in the axial direction to press the hub side friction plate and the drum side friction plate together. A hydraulic chamber F2 into which hydraulic pressure supplied from the hydraulic control circuit 14 is introduced is defined adjacent to the piston P2, and the hub side friction plate and the drum side friction plate are pressed or released in response to the supply and discharge of hydraulic pressure to the hydraulic chamber F2, thereby connecting and disconnecting the first ring gear R1 and the second sun gear S2 from the third sun gear S3.

The third clutch CL3 has a rotatable inner holding member connected to the third sun gear S3 via power transmission members 24d and 24e, a hub side friction plate engaged with the outer peripheral surface of the inner holding member, a rotatable outer holding member connected to the second ring gear R2 via power transmission member 24g, a drum side friction plate engaged with the inner peripheral surface of the outer holding member, and a piston P3 that is driven forward and backward in the axial direction to press the hub side friction plate and the drum side friction plate together. A hydraulic chamber F3 into which hydraulic pressure supplied from the hydraulic control circuit 14 is introduced is defined adjacent to the piston P3, and the hub side friction plate and the drum side friction plate are pressed or released in response to the supply and discharge of hydraulic pressure to the hydraulic chamber F3, thereby connecting and disconnecting the second ring gear R2 and the third sun gear S3.

The first brake BR1 connects and disconnects the transmission case 20a and the first sun gear S1 (more specifically, the front first sun gear S1a). The second brake BR2 connects and disconnects the transmission case 20a and the third ring gear R3.

Specifically, the first brake BR1 has a rotatable inner retaining member connected to the front first sun gear S1a via a power transmission member 24h, a hub side friction plate engaged with the outer circumferential surface of the inner retaining member, a non-rotatable outer retaining member connected to the transmission case 20a, a drum side friction plate engaged with the inner circumferential surface of the outer retaining member, and a piston P4 that is driven forward and backward in the axial direction to press the hub side friction plate and the drum side friction plate together. A hydraulic chamber F4 is defined adjacent to the piston P4, into which hydraulic pressure supplied from the hydraulic control circuit 14 is introduced, and the hub side friction plate and the drum side friction plate are pressed or released in response to the supply and discharge of hydraulic pressure to the hydraulic chamber F4, thereby connecting and disconnecting the transmission case 20a and the first sun gear S1.

The second brake BR2 has a rotatable inner retaining member connected to the third ring gear R3, a hub side friction plate engaged with the outer peripheral surface of the inner retaining member, a non-rotatable outer retaining member connected to the transmission case 20a, a drum side friction plate engaged with the inner peripheral surface of the outer retaining member, and a piston P5 that is driven forward and backward in the axial direction to press the hub side friction plate and the drum side friction plate together. A hydraulic chamber F5 into which hydraulic pressure supplied from the hydraulic control circuit 14 is introduced is defined adjacent to the piston P5, and the hub side friction plate and the drum side friction plate are pressed together or released in response to the supply and discharge of hydraulic pressure to the hydraulic chamber F5, thereby connecting and disconnecting the transmission case 20a and the third ring gear R3.

The transmission case 20a has an annular vertical wall portion W1 extending radially inward from the inner peripheral surface of the transmission case 20a at an axial position between the first brake BR1 and the third clutch CL3, and a cylindrical wall portion W2 extending rearward from the inner peripheral end of the vertical wall portion W1. The cylindrical wall portion W2 is formed to extend concentrically along the inner peripheral surface of the power transmission member 24e.

Three housings are formed radially outside the power transmission member 24e and aligned in the axial direction, and these three housings house the pistons P1, P2, and P3 of the first clutch CL1, second clutch CL2, and third clutch CL3, respectively.

The vertical wall portion W1, the cylindrical wall portion W2, and the power transmission member 24e are provided with oil passages for supplying oil pressure to the hydraulic chambers F1, F2, and F3 of the first clutch CL1, the second clutch CL2, and the third clutch CL3, respectively. Specifically, the vertical wall portion W1 and the cylindrical wall portion W2 are provided with oil passages a, and the power transmission member 24e is provided with oil passages b, c, and d. Oil pressure is supplied to the hydraulic chamber F1 of the first clutch CL1 through the oil passages a and b, to the hydraulic chamber F2 of the second clutch CL2 through the oil passages a and c, and to the hydraulic chamber F3 of the third clutch CL3 through the oil passages a and d.

Although not shown, the communication parts between the oil passage a and the oil passages b, c, and d between the outer circumferential surface of the cylindrical wall portion W2 and the inner circumferential surface of the power transmission member 24e are each sealed by a seal ring.

The piston P4 of the first brake BR1 is housed in a housing formed in front of the vertical wall portion W1. The hydraulic chamber F4 defined by the housing is directly connected to an oil passage e from the outside of the transmission case 20a.

The piston P5 of the second brake BR2 is housed in a housing that is fitted to the inner circumferential surface of the rear of the transmission case 20a. The hydraulic chamber F5 defined by this housing is directly connected to the oil passage f from the outside of the transmission case 20a.

According to the automatic transmission 20 configured as described above, as shown in the engagement table in Figure 3, three specific frictional engagement elements out of the five frictional engagement elements (CL1, CL2, CL3, BR1, BR2) are selectively engaged based on the supply and discharge control of hydraulic pressure to the hydraulic chambers F1 to F5, thereby forming either the first to eighth forward gears or reverse gear. Also, as shown in Figure 3, when starting the vehicle in first forward gear, the first clutch CL1, which is the first frictional engagement element 22a, the first brake BR1, which is the fourth frictional engagement element 22d, and the second brake BR2, which is the fifth frictional engagement element 22e, are engaged. In other words, the first clutch CL1, the first brake BR1, and the second brake BR2 form the starting gear for first forward gear. On the other hand, when starting the vehicle in reverse, the third clutch CL3, which is the third frictional engagement element 22c, the first brake BR1, which is the fourth frictional engagement element 22d, and the second brake BR2, which is the fifth frictional engagement element 22e, are engaged. In other words, the third clutch CL3, the first brake BR1, and the second brake BR2 constitute the reverse start gear.

In this embodiment, the second brake BR2 of the automatic transmission 20 is configured as a "zero-touch clutch." In this specification, the term "zero-touch clutch" refers to a clutch or brake in which the friction plates (drive plate and driven plate) constituting the second brake BR2, which is a frictional engagement element, are in a "zero-touch state." The "zero-touch state" refers to a state in which the clearance between the friction plates constituting the frictional engagement element is reduced to the point of being frictionally engaged. Therefore, in this embodiment, it can be said that the clearance between the friction plates constituting the second brake BR2 of the automatic transmission 20 is substantially zero. For this reason, in this embodiment, the second brake BR2, which is a frictional engagement element, is engaged by simply supplying a small amount of hydraulic pressure, and therefore extremely high responsiveness can be obtained.

Next, the hydraulic control circuit 14 in the hydraulic control device according to the embodiment of the present invention will be described with reference to FIG.
4, the hydraulic control circuit 14 has five fastening hydraulic control valves 16a to 16e which are first to fifth fastening hydraulic control valves, and a flow control valve 18 which controls the flow rate of hydraulic oil supplied to these fastening hydraulic control valves 16a to 16e. The hydraulic control circuit 14 also has a hydraulic pump 26 which supplies hydraulic oil to the flow control valve 18, and an oil pan 28 which stores the hydraulic oil pumped up by the hydraulic pump 26.

The hydraulic pump 26 is configured to pump up hydraulic oil stored in the oil pan 28 and supply it to the flow control valve 18. The hydraulic oil whose flow rate is adjusted by the flow control valve 18 is supplied to the first fastening hydraulic control valve 16a to the fifth fastening hydraulic control valve 16e, respectively. In addition, the flow control valve 18 and the hydraulic pump 26 are controlled by the ECU 12 based on detection signals from the ATF water temperature sensor 8 (Figure 1) and the like, and supply appropriate hydraulic pressure to each frictional fastening element.

As shown in FIG. 4, the first engagement hydraulic control valve 16a is connected to the first clutch CL1, which is the first frictional engagement element 22a of the automatic transmission 20. Furthermore, the second engagement hydraulic control valve 16b is connected to the second clutch CL2, which is the second frictional engagement element 22b, and the third engagement hydraulic control valve 16c is connected to the third clutch CL3, which is the third frictional engagement element 22c. Furthermore, the fourth engagement hydraulic control valve 16d is connected to the first brake BR1, which is the fourth frictional engagement element 22d, and the fifth engagement hydraulic control valve 16e is connected to the second brake BR2, which is the fifth frictional engagement element 22e.

For this reason, for example, when the first engagement hydraulic control valve 16a is energized, hydraulic pressure is supplied to the first clutch CL1, which is the corresponding first frictional engagement element 22a of the automatic transmission 20, and this is engaged. Also, when the first engagement hydraulic control valve 16a is de-energized, the hydraulic pressure in the first clutch CL1 is released, the engagement is released, and the hydraulic oil is collected in the oil pan 28 via the first engagement hydraulic control valve 16a. In this way, by energizing the first to fifth engagement hydraulic control valves 16a to 16e provided corresponding to the first to fifth frictional engagement elements 22a to 22e, respectively, each frictional engagement element can be engaged. Furthermore, the first to fifth frictional engagement elements 22a to 22e are provided with first to fifth engagement hydraulic sensors 10a to 10e, which detect the hydraulic pressure supplied to each frictional engagement element.

Next, the configuration and operation of the fastening hydraulic control valve provided in the hydraulic control device according to the embodiment of the present invention will be described with reference to FIGS.
Fig. 5 is a cross-sectional view of the fastening hydraulic control valve in an energized state. Fig. 6 is a cross-sectional view of the fastening hydraulic control valve in a de-energized state. Fig. 7 is a graph showing an example of the action of the fastening hydraulic control valve when sticking occurs. Fig. 8 is a diagram showing an example of a sticking prevention current waveform supplied to a coil of the fastening hydraulic control valve. Fig. 9 is a graph showing the relationship between the current supplied to the fastening hydraulic control valve and the hydraulic pressure supplied to a frictional fastening element provided corresponding to the current.

As shown in FIG. 5, the fifth fastening hydraulic control valve 16e has a cylinder 30, a spool 32 that slides within the cylinder 30, and a solenoid valve 34 that drives the spool. Note that while the configuration of the fifth fastening hydraulic control valve 16e will be described here, the first to fifth fastening hydraulic control valves 16a to 16e provided in the hydraulic control device of this embodiment all have the same configuration.

The cylinder 30 is a cylindrical tube with one end closed and the other end open. Three ports 30a, 30b, and 30c are provided on the outer circumferential surface of the cylinder 30. The first port 30a is connected to the flow control valve 18, and the hydraulic oil flowing out from the flow control valve 18 flows into the cylinder 30 through the first port 30a. The second port 30b is connected to the corresponding frictional fastening element 22. Therefore, the second port 30b of the cylinder 30 of the fifth fastening hydraulic control valve 16e (FIG. 4) is connected to the hydraulic chamber F5 (FIG. 2) of the second brake BR2 of the automatic transmission 20. Furthermore, the third port 30c is configured to allow the hydraulic oil in the cylinder 30 to flow out, and the hydraulic oil flowing out from the third port 30c is collected in the oil pan 28.

The solenoid valve 34 is configured to slide the spool 32 in the cylinder 30 by passing a predetermined control current through the built-in coil 34a. That is, when a predetermined control current is applied to the coil 34a of the solenoid valve 34, the spool 32 is moved to the position shown in FIG. 5, and the fastening hydraulic control valve 16 is in a state of supplying hydraulic pressure to the frictional fastening element 22. On the other hand, when the coil 34a of the solenoid valve 34 is not energized, the spool 32 is moved to the position shown in FIG. 6, and the fifth fastening hydraulic control valve 16e is in a state of not supplying hydraulic pressure to the fifth frictional fastening element 22e. That is, the solenoid valve 34 is a normally closed solenoid configured to switch the corresponding frictional fastening element 22 to an engaged state when a predetermined control current is applied, and switch the frictional fastening element 22 to a non-engaged state when no control current is applied. In addition, in this embodiment, the solenoid valve 34 can basically be an ON/OFF solenoid that is used to move the spool 32 to one of two positions, the position shown in FIG. 5 or the position shown in FIG. 6.

The spool 32 is a stepped cylindrical part that is slidably arranged inside the cylinder 30 and is configured to open and close each port of the cylinder 30. In addition, a biasing spring 36 is arranged between the tip of the spool 32 and the closed end of the cylinder 30. This biasing spring 36 is a coil spring arranged inside the cylinder 30 and biases the spool 32 toward the open end of the cylinder 30. Therefore, when the coil 34a of the solenoid valve 34 is energized, the spool 32 is driven by the solenoid valve 34 to the position shown in FIG. 5 against the biasing force of the biasing spring 36. On the other hand, when the coil 34a of the solenoid valve 34 is de-energized, the spool 32 is moved to the position shown in FIG. 6 by the biasing force of the biasing spring 36.

The spool 32 is formed with a first large diameter portion 32c , a small diameter portion 32b, and a second large diameter portion 32a in that order from the tip, and each large diameter portion is configured to have a diameter substantially equal to the inner diameter of the cylinder 30. Therefore, the sliding of the spool 32 changes the connection state of each port of the cylinder 30. That is, in the energized state of the solenoid valve 34 shown in FIG. 5, the first port 30a and the second port 30b are aligned with the small diameter portion 32b of the spool 32, so that the first port 30a and the second port 30b are communicated with each other. As a result, the hydraulic oil supplied from the flow control valve 18 is supplied to the frictional engagement element 22 provided corresponding to the first port 30a and the second port 30b are switched to the engagement state. On the other hand, the third port 30c is blocked by the second large diameter portion 32a .

6, the second port 30b and the third port 30c are aligned with the small diameter portion 32b of the spool 32, so that the second port 30b and the third port 30c are communicated with each other. As a result, the hydraulic oil in the frictional fastening element 22 flows out to the oil pan 28 via the cylinder 30 of the fastening hydraulic control valve 16. On the other hand, the hydraulic oil that flows into the cylinder 30 from the flow control valve 18 via the first port 30a is stopped by the first large diameter portion 32c of the spool 32 and remains in the cylinder 30.

In this way, the engagement/disengagement of each frictional engagement element 22 is achieved by operating the corresponding engagement hydraulic control valve 16 and switching between supplying and not supplying hydraulic pressure to each frictional engagement element 22. The control device 12a built into the ECU 12 switches between engagement/disengagement of the frictional engagement element 22 provided corresponding to the engagement hydraulic control valve 16 by passing a predetermined control current through the solenoid valve 34 of each engagement hydraulic control valve 16.

However, when control current is not applied to the solenoid valve 34 of the fastening hydraulic control valve 16 for a long period of time, such as when the vehicle is parked or stopped, the spool 32 of the fastening hydraulic control valve 16 may become stuck in the position shown in FIG. 6 within the cylinder 30. In this way, when the spool 32 becomes stuck, even if the control device 12a applies control current to the solenoid valve 34, the fastening hydraulic control valve 16 is not immediately switched, and a delay occurs in switching the fastening hydraulic control valve. In particular, if there is a delay in switching the fifth fastening hydraulic control valve 16e corresponding to the fifth frictional fastening element 22e that is to be fastened when starting, the starting responsiveness of the vehicle decreases.

Figure 7 is a graph showing an example of the behavior of the fastening hydraulic control valve 16 when sticking occurs, with the horizontal axis showing time and the vertical axis showing the hydraulic pressure supplied to the frictional fastening element 22 provided corresponding to the fastening hydraulic control valve 16. In Figure 7, the solid line shows the change in hydraulic pressure in a normal fastening hydraulic control valve 16 where no sticking has occurred, and the dashed line shows the change in hydraulic pressure in a fastening hydraulic control valve 16 where sticking has occurred.

As shown by the solid line in Fig. 7, in the fastening hydraulic control valve 16 where no sticking has occurred, when the supply of electricity to the coil 34a of the solenoid valve 34 starts at time _t0 , the hydraulic pressure starts to rise at time _t1 , approximately 0.7 seconds later. Next, the hydraulic pressure once becomes constant, and then draws a curve in which it rises sharply again at time _t2 . Meanwhile, the dashed line in Fig. 7 shows the change in hydraulic pressure when the coil 34a of the fastening hydraulic control valve 16 is not supplied with electricity for about one hour, and the spool 32 of the fastening hydraulic control valve 16 is intentionally kept stuck, and then the coil 34a is supplied with electricity.

As shown by the dashed line in Fig. 7, in the engagement hydraulic control valve 16 where sticking has occurred, after the start of energization of the coil 34a of the solenoid valve 34 at time _t0 , no increase in hydraulic pressure is observed for a while, and the hydraulic pressure starts to increase at time _t3 , about 2.9 seconds after the start of energization at time _t0 . The behavior of the engagement hydraulic control valve 16 illustrated in Fig. 7 is not based on the actual operating conditions of the automatic transmission 20, but it has been confirmed that if the coil 34a is not energized for a long period of time and the spool 32 sticks, a delay occurs in the supply of hydraulic pressure to the frictional engagement element 22. In this way, when the engagement hydraulic control valve 16 sticks, the increase in hydraulic pressure of the frictional engagement element 22 provided correspondingly is delayed, and the responsiveness of the automatic transmission 20 decreases.

In the hydraulic control device of this embodiment, the control device 12a of the ECU 12 supplies a sticking prevention current to the solenoid valve 34 provided in correspondence with the frictional fastening element 22 that is engaged at the time of starting. That is, in this embodiment, as shown in FIG. 4, the first fastening hydraulic control valve 16a is provided in correspondence with the first frictional fastening element 22a, the second fastening hydraulic control valve 16b is provided in correspondence with the second frictional fastening element 22b, the third fastening hydraulic control valve 16c is provided in correspondence with the third frictional fastening element 22c, the fourth fastening hydraulic control valve 16d is provided in correspondence with the fourth frictional fastening element 22d, and the fifth fastening hydraulic control valve 16e is provided in correspondence with the fifth frictional fastening element 22e. The control device 12a is configured to supply a sticking prevention current to the coil 34a of the solenoid valve 34 of the fifth fastening hydraulic control valve 16e provided in correspondence with one of the frictional fastening elements that is engaged at the time of starting among these fastening hydraulic control valves.

FIG. 8 is a diagram showing an example of a waveform of a sticking prevention current supplied to the coil 34a of the solenoid valve 34 of the fifth fastening hydraulic control valve 16e.
As shown in Fig. 8, the anti-sticking current is supplied in the form of a single pulse. In this embodiment, after the engine of the vehicle is started and before the vehicle starts moving, the anti-sticking current is supplied in the form of a pulse for a period of about 10 mSec. In addition, in this embodiment, the current supplied during the current supply period of about 10 mSec is set to be less than the control current of the fastening hydraulic control valve 16. In this manner, by supplying the anti-sticking current to the coil 34a of the fifth fastening hydraulic control valve 16e, the spool 32, which is in the position shown in Fig. 6, moves slightly toward the position shown in Fig. 5 and returns to its original position.

Next, referring to FIG. 9, the relationship between the current supplied to the coil 34a of the fastening hydraulic control valve 16 and the hydraulic pressure supplied to the frictional fastening element 22 provided correspondingly thereto will be described. As described above, when a "control current" is supplied to the coil 34a of the solenoid valve 34 of the fastening hydraulic control valve 16, the spool 32 is moved to the state shown in FIG. 5. In this state, the first port 30a and the second port 30b of the cylinder 30 are fully opened, so that the hydraulic pressure from the flow control valve 18 is sufficiently supplied to the corresponding frictional fastening element 22, and the frictional fastening element 22 is brought into a fastened state. As shown in FIG. 9, in this embodiment, the control current for the fastening hydraulic control valve 16 is about 1 [A].

On the other hand, in this embodiment, the "anti-sticking current" supplied to the coil 34a of the fifth fastening hydraulic control valve 16e is supplied in a pulsed manner as shown in FIG. 8. This "anti-sticking current" is set to about 0.5 [A], which is less than the "control current". In this way, by supplying the pulsed "anti-sticking current" to the coil 34a of the solenoid valve 34 of the fastening hydraulic control valve 16, the spool 32 of the fastening hydraulic control valve 16 starts to move from the state shown in FIG. 6 to the position shown in FIG. 5. However, since the energization period of the "anti-sticking current" is very short, high oil pressure is not generated in the fifth frictional fastening element 22e provided corresponding to the fifth fastening hydraulic control valve 16e. However, at the moment when the anti-sticking current flows to the coil 34a, the spool 32 moves, so a thin oil film is formed between the cylinder 30 and the spool 32, and the occurrence of sticking of the spool 32 is suppressed.

In this embodiment, the current supplied in pulses as the "anti-sticking current" is set to approximately 0.5 A, which is less than the "control current." However, as a modified example, the "anti-sticking current" can be set to a current value approximately equal to that of the "control current."

Next, the operation of the hydraulic control device according to the embodiment of the present invention will be described with reference to FIG.
Fig. 10 is a flowchart showing the process executed by the control device 12a of the ECU 12 in the hydraulic control device according to the embodiment of the present invention. The process according to the flowchart shown in Fig. 10 is executed when the power of the vehicle equipped with the automatic transmission 20 while parked or stopped is turned on. The flowchart in Fig. 10 also shows the process for setting the current to be supplied to the coil 34a of the solenoid valve 34 of the fifth engagement hydraulic control valve 16e, which is a "zero touch clutch".

First, in step S1 of FIG. 10, it is determined whether or not the engine (not shown) of the vehicle equipped with the automatic transmission 20 has been started. If the driver has performed an operation to start the engine (not shown), the process proceeds to step S2, and if the driver has not performed the start operation, the process in step S1 is repeated. When the engine (not shown) is started, the hydraulic pump 26 is operated and hydraulic pressure is supplied to the hydraulic control circuit 14.

Next, in step S2, it is determined whether the multiple frictional fastening elements 22 are engaged. Whether each frictional fastening element 22 is engaged is determined based on the detection signal of the fastening hydraulic sensor 10 (Figure 4) provided corresponding to each frictional fastening element 22. If the pressure detected by the fastening hydraulic sensor 10 is equal to or greater than a predetermined pressure, it is determined that the frictional fastening element 22 provided corresponding to that fastening hydraulic sensor 10 is engaged. If it is determined that multiple frictional fastening elements 22 are engaged, the process proceeds to step S12, and if there is zero or one frictional fastening element 22 that is engaged, the process proceeds to step S3.

In step S3, the supply of anti-stick current to the solenoid valve 34 of the fifth engagement hydraulic control valve 16e corresponding to the second brake BR2, which is the fifth frictional engagement element 22e, is started. Here, as described above, since the second brake BR2 is a zero-touch clutch, there is a risk that the second brake BR2 will be engaged even if the anti-stick current is supplied for only a short period of time. In such a case, for example, if the first engagement hydraulic control valve 16a (first clutch C1) and the fourth engagement hydraulic control valve 16d (first brake BR1) are engaged, there is a risk that the vehicle will start unintentionally due to the engagement of the second brake BR2.

However, since it is confirmed in step S2 that zero or one frictional fastening element 22 is engaged, it is possible to reliably prevent the vehicle from starting unexpectedly. That is, as shown in FIG. 3, in this embodiment, the automatic transmission 20 is configured to transmit power when three frictional fastening elements 22 are simultaneously engaged, so that even if the second brake BR2 is engaged when zero or one frictional fastening element 22 is engaged, no power is transmitted. As a modified example, the present invention can be configured so that the anti-stick current is supplied only when there are no frictional fastening elements in an engaged state, or it can be confirmed that no power is transmitted by the automatic transmission based on other conditions.

Next, in step S4, it is determined whether or not a predetermined time has elapsed after the supply of the anti-sticking current was started in step S3. As described above, in this embodiment, the period during which the anti-sticking current is supplied is about 10 mSec (FIG. 8).
If the predetermined time has not elapsed since the start of the supply of the anti-sticking current, the process proceeds to step S6, where it is determined whether or not a shifter (not shown) provided in the vehicle has been switched to the drive range. If the shifter has not been switched to the drive range in step S6, the process returns to step S4, and thereafter, the process of steps S4 → S6 → S4 is repeated until the predetermined time has elapsed.

After the supply of the anti-sticking current has started, and a predetermined time has elapsed, the process proceeds to step S5, where the supply of the anti-sticking current to the solenoid valve 34 of the fifth fastening hydraulic control valve 16e is stopped. This ends the supply of the anti-sticking current for the predetermined time of about 10 mSec, and the process proceeds to step S8. This supply of the anti-sticking current drives the spool 32 of the fifth fastening hydraulic control valve 16e from the state shown in FIG. 6 to the left in the figure, and then returns to the state shown in FIG. 6. This resolves the sticking of the spool 32 to the cylinder 30, even if it had been stuck.

On the other hand, if the driver switches the vehicle's shifter (not shown) to the drive range before the predetermined time has elapsed after the supply of the anti-sticking current has started in step S3, the process in the flowchart proceeds from step S6 to step S7. In step S7, the supply of the anti-sticking current to the solenoid valve 34 of the fifth engagement hydraulic control valve 16e is stopped midway before the predetermined time has elapsed. That is, if the shifter (not shown) is switched to the drive range while the anti-sticking current is being supplied, the frictional engagement elements (first clutch C1 and first brake BR1) that are engaged when starting off other than the second brake BR2 may be engaged, causing the vehicle to start. For this reason, if the shifter (not shown) is switched to the drive range while the anti-sticking current is being supplied, the supply of the anti-sticking current is stopped (step S7) and the process proceeds to step S8.

In this embodiment, the anti-stick current is supplied for an extremely short period of time (approximately 10 mSec), and the possibility that the shifter (not shown) will be switched to the drive range during this period is extremely low. In this embodiment, steps S6 and S7 are included to deal with this extremely low risk. Also, by including steps S6 and S7, it is possible to set the period during which the anti-stick current is supplied to be relatively long.

On the other hand, if it is determined in step S2 that multiple frictional engagement elements 22 are engaged, the process proceeds to step S8. That is, if multiple frictional engagement elements 22 are engaged after the engine (not shown) is started, the supply of an anti-sticking current is not executed because there is a risk that the vehicle will start unexpectedly if the fifth frictional engagement element 22e (second brake BR2) is engaged due to the supply of an anti-sticking current. Note that when the vehicle is parked or stopped, the automatic transmission 20 is normally in neutral and all frictional engagement elements 22 are disengaged. However, even if any of the frictional engagement elements 22 are engaged due to a malfunction or the like, the state of the frictional engagement elements 22 is checked in step S2 to prevent the vehicle from starting unexpectedly.

Next, in step S8, it is determined whether the driver has switched the vehicle's shifter (not shown) to the drive range, and if it has not been switched, the process of step S8 is repeated. That is, after the supply of the anti-stick current is terminated in step S5, or after it is determined in step S2 that the multiple frictional engagement elements 22 are engaged, the process waits until the driver switches the shifter (not shown) to the drive range, and then proceeds to step S9. Note that if it is determined in step S6 that the shifter (not shown) has already been switched to the drive range, the process proceeds to step S9 without waiting.

In step S9, the control device 12a supplies a control current to the solenoid valves 34 of the first engagement hydraulic control valve 16a and the fourth engagement hydraulic control valve 16d, and engages the corresponding first frictional engagement element 22a (first clutch C1) and fourth frictional engagement element 22d (first brake BR1). As a result, of the frictional engagement elements 22 that are engaged when the vehicle starts, the frictional engagement elements 22 other than the fifth frictional engagement element 22e, which is a zero-touch clutch, are engaged.

Next, in step S10, it is determined whether a start command has been input to the ECU 12, and if a start command has not been input, the process of step S10 is repeated. In this embodiment, if the depression amount of the accelerator pedal (not shown) detected by the throttle opening sensor 4 is equal to or greater than a predetermined threshold value and the brakes (foot brake and parking brake) are turned off, it is determined that a start command has been input to the ECU 12.

When a start command is input, the process proceeds to step S11, where the control device 12a supplies a control current to the solenoid valve 34 of the fifth engagement hydraulic control valve 16e, and engages the corresponding fifth frictional engagement element 22e (second brake BR2). In this way, by engaging the fifth frictional engagement element 22e when the vehicle starts, the automatic transmission 20 transmits the power of the engine (not shown), and the vehicle starts. Here, since the fifth frictional engagement element 22e (second brake BR2) is configured as a zero-touch clutch, when a control current is supplied, it is brought into an engaged state in an extremely short time. Therefore, the vehicle starts in immediate response to the driver's start operation.

Next, in step S12, normal shift control of the automatic transmission 20 is started, and the process of the flowchart shown in FIG. 10 ends. In normal shift control, the control device 12a sets an appropriate gear based on detection signals from the vehicle speed sensor 2, throttle opening sensor 4, turbine speed sensor 6, etc. Then, the control device 12a sends control signals to each engagement hydraulic control valve 16 to selectively engage the first through fifth frictional engagement elements 22a through 22e so that the gear is achieved.

According to the hydraulic control device of the embodiment of the present invention, after the engine of the vehicle is started and before starting, the control device 12a supplies an anti-sticking current to the solenoid valve 34 of the fifth engagement hydraulic control valve 16e, which is provided corresponding to the fifth frictional engagement element 22e that is engaged at the time of starting, among the frictional engagement elements 22 (step S3 in FIG. 10). This suppresses the occurrence of sticking of the spool 32 of the fifth engagement hydraulic control valve 16e. In other words, by supplying an anti-sticking current to the solenoid valve 34, the sticking of the spool 32, which is a part driven by the solenoid valve 34, is eliminated, and the vehicle can be started smoothly when the driver performs a start operation. In addition, since the hydraulic pump 26 is operating after the vehicle engine starts, when an anti-stick current is supplied to the solenoid valve 34, the fifth frictional engagement element 22e provided in correspondence with that solenoid valve 34 is brought into an engaged state. However, since the anti-stick current is supplied before the vehicle starts, the engagement of the fifth frictional engagement element 22e does not cause the vehicle to start.

In addition, according to the hydraulic control device of this embodiment, the anti-stick current supplied after the engine starts and before the vehicle starts is set to a current lower than the control current (Figure 8), so that the power consumption due to the supply of the anti-stick current can be reduced, and the occurrence of sticking can be reduced with low power consumption.

Furthermore, according to the hydraulic control device of this embodiment, when a control current is supplied to the solenoid valve 34, hydraulic pressure is supplied to the corresponding frictional fastening element 22 (Figure 9) and the solenoid valve 34 is put into an engaged state, so the solenoid valve 34 can be put into an unfastened state without current being passed through it, reducing current consumption. In addition, the anti-sticking current that is supplied after the engine starts and before the vehicle starts only needs to be a very small current, so the amount of current consumed to prevent sticking can be further reduced.

In addition, according to the hydraulic control device of this embodiment, before the vehicle starts, the anti-stick current is supplied only to the solenoid valve 34 provided for the fifth frictional fastening element 22e, which is a zero-touch clutch (step S3 in FIG. 10), so that the supply of the anti-stick current can reliably prevent the vehicle from starting.

Furthermore, according to the hydraulic control device of this embodiment, after the supply of anti-sticking current to the fifth frictional engagement element 22e, which is the zero-touch clutch, is stopped (step S5 in FIG. 10), the frictional engagement elements other than the zero-touch clutch that is engaged when starting are engaged (step S9 in FIG. 10). Therefore, when starting the vehicle, the vehicle can be started simply by supplying a control current to the solenoid valve 34 provided corresponding to the zero-touch clutch (step S11 in FIG. 10), thereby making it possible to achieve extremely good responsiveness when starting the vehicle.

Although an embodiment of the present invention has been described above, various modifications can be made to the above-described embodiment. In particular, in the above-described embodiment, the present invention is applied to an automatic transmission equipped with six clutches including a zero-touch clutch and two brakes, but the present invention can be applied to any type of automatic transmission.

In the above-described embodiment, a normally closed solenoid was used as the solenoid valve 34 provided in the fastening hydraulic control valve 16, which is supplied with hydraulic pressure by supplying a control current to fasten the frictional fastening element 22. In contrast, as a modified example, a normally open solenoid can be used, in which hydraulic pressure is supplied by stopping the control current to fasten the frictional fastening element 22. In this case, when hydraulic pressure is supplied to the frictional fastening element 22, the control current to the solenoid valve is stopped (current = 0), and when the supply of hydraulic pressure to the frictional fastening element 22 is stopped, a predetermined control current is supplied to the solenoid valve. Furthermore, the anti-sticking current is supplied intermittently. It is also possible to mix normally closed solenoids and normally open solenoids in a hydraulic control circuit.

REFERENCE SIGNS LIST 1 Automatic transmission system 2 Vehicle speed sensor 4 Throttle opening sensor 6 Turbine rotation speed sensor 8 ATF water temperature sensor 10 Fastening hydraulic pressure sensor 12 ECU
Reference Signs List 12a Control device 14 Hydraulic control circuit 16 Fastening hydraulic control valve 18 Flow control valve 20 Automatic transmission 20a Transmission case 20b Input shaft 20c Output shaft 22 Friction fastening element 24a Power transmission member 24b Power transmission member 24c Power transmission member 24d Power transmission member 24e Power transmission member 24f Power transmission member 24g Power transmission member 24h Power transmission member 26 Hydraulic pump 28 Oil pan 30 Cylinder 30a First port 30b Second port 30c Third port 32 Spool 32a Second large diameter portion
32b small diameter portion 32c first large diameter portion
34 Solenoid valve 34a Coil 36 Spring

Claims (5)

A hydraulic control device for an automatic transmission that performs gear shifting by switching between engagement and non-engagement of a plurality of frictional engagement elements,
A hydraulic pump;
a flow control valve that adjusts the flow rate of hydraulic oil supplied from the hydraulic pump;
an engagement hydraulic control valve provided corresponding to each of the frictional engagement elements, for switching between supply and non-supply of hydraulic oil, supplied from the flow control valve, to each of the frictional engagement elements, thereby switching between engagement and non-engagement of each of the frictional engagement elements;
a control device that switches between supplying and not supplying hydraulic pressure to each of the frictional engagement elements by supplying a predetermined control current to the engagement hydraulic control valves;
having
The fastening hydraulic control valve is
a solenoid valve to which a control current is supplied from the control device;
a spool driven by the solenoid valve;
a cylinder in which the spool slides;
a biasing spring disposed between the closed end of the cylinder and the tip of the spool;
having
The spool is
A first large diameter portion, a small diameter portion, and a second large diameter portion are formed in this order from the tip,
The cylinder is
A first port connected to the flow control valve;
a second port located closer to the solenoid valve than the first port and connected to a frictional fastening element to which hydraulic pressure is to be supplied;
a third port that is located closer to the solenoid valve than the second port, that can be closed by the second large diameter portion, and that allows the hydraulic oil in the cylinder to flow out;
Equipped with
the first port is located closer to the closed end of the cylinder than the second large diameter portion of the spool is when the solenoid valve is de-energized,
The control device is a hydraulic control device configured to supply a single pulse-shaped anti-stick current to the engagement hydraulic control valve provided corresponding to one of the frictional engagement elements that is engaged when the vehicle starts, after an engine of a vehicle equipped with the automatic transmission is started and before the vehicle starts. A hydraulic control device for an automatic transmission that performs gear shifting by switching between engagement and non-engagement of a plurality of frictional engagement elements,
an engagement hydraulic control valve provided for each of the frictional engagement elements, for switching between supplying and not supplying hydraulic pressure to each of the frictional engagement elements, thereby switching between engagement and non-engagement of each of the frictional engagement elements;
a control device that switches between supplying and not supplying hydraulic pressure to each of the frictional engagement elements by supplying a predetermined control current to the engagement hydraulic control valves;
having
the control device is configured to supply an anti-sticking current to the engagement hydraulic control valve provided corresponding to a frictional engagement element that is engaged when the vehicle is started, among the frictional engagement elements, after an engine of a vehicle equipped with the automatic transmission is started and before the vehicle is started,
At least one of the plurality of frictional fastening elements is a zero-touch clutch in which the clearance between the friction plates constituting the frictional fastening element is substantially zero, and when a vehicle equipped with the automatic transmission starts, the plurality of frictional fastening elements including the zero-touch clutch are engaged, and the control device is configured to supply the anti-sticking current only to an engagement hydraulic control valve provided corresponding to the zero-touch clutch. The hydraulic control device according to claim 2, wherein the control device engages a frictional engagement element other than the zero-touch clutch that is engaged when the vehicle equipped with the automatic transmission starts after stopping the supply of the anti-sticking current to the zero-touch clutch. The hydraulic control device according to any one of claims 1 to 3, wherein the anti-sticking current supplied after the engine of the vehicle is started and before the vehicle starts moving is set to a current lower than the control current. 5. The hydraulic control device according to claim 1, wherein at least one of the engagement hydraulic control valves is configured such that, when the control current is supplied, a corresponding frictional engagement element is switched to an engagement state.

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