JP4289059B2 - Hydraulic control device for automatic transmission for vehicle - Google Patents

Description

  The present invention relates to a hydraulic control device for an automatic transmission for a vehicle, and more particularly to a hydraulic control device that electrically switches forward and backward according to a switch operation of a driver.

2. Description of the Related Art A hydraulic control device for a vehicular automatic transmission in which a forward shift stage is established by forward hydraulic pressure and a reverse shift stage is established by reverse hydraulic pressure is widely used. Generally, a manual valve is operated according to a driver's shift lever operation. Is moved mechanically, the hydraulic circuit is switched to establish the forward shift stage, the reverse shift stage, the neutral for interrupting power transmission, and the like. On the other hand, in recent years, it has been proposed to electrically switch the forward / reverse movement of the automatic transmission according to the driver's switch operation. For example, in Patent Document 1, two solenoid valves (S3, S4) and three solenoid valves are proposed. Using the switching valve, the forward gear, the reverse gear, and the neutral are switched. That is, as shown in FIG. 4 of the same document, the reverse gear is established when both the solenoid valves S3 and S4 are ON, the neutral is established when both the solenoid valves S3 and S4 are OFF, S3 is ON and S4 is OFF. At this time, the forward gear is established.
JP-A-5-209683

  By the way, in such a conventional hydraulic control device, when the solenoid valve S4 is turned OFF due to disconnection or the like, the reverse shift speed is changed to the forward shift speed, so that it does not move forward when the reverse travel switch is selected. For example, when the reverse travel switch is selected and operated at the time of failure of the solenoid valve S4, it is necessary to electrically achieve fail-safe such that the solenoid valve S3 is also turned OFF to be neutral.

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to prevent forward / reverse movement from being changed by a failure of a switching device such as a solenoid valve.

In order to achieve this object, the first invention provides a hydraulic control device for an automatic transmission for a vehicle in which a forward shift stage is established by forward hydraulic pressure and a reverse shift stage is established by reverse hydraulic pressure. A forward valve that switches between output and output stop of the forward hydraulic pressure, (b) a reverse valve that switches between output and output stop of the backward hydraulic pressure, and (c) forward switching hydraulic pressure when the forward switching signal is ON or OFF. A forward switching device for switching the forward valve to an output state by outputting, and (d) a reverse switching for switching the reverse valve to an output state by outputting a reverse switching hydraulic pressure when the reverse switching signal is turned ON or OFF. And (e) the forward valve outputs an output stop of the forward hydraulic pressure regardless of the presence of the forward switching hydraulic pressure when the reverse switching hydraulic pressure is output. The reverse valve is held in the output stop state of the reverse hydraulic pressure regardless of the presence of the reverse switch hydraulic pressure when the forward switch hydraulic pressure is output, and (f) the forward switch When the hydraulic pressure is output and the reverse switching hydraulic pressure is stopped, the forward hydraulic pressure is output from the forward valve to establish the forward shift speed, and (g) the reverse switching hydraulic pressure is output and By stopping the output of the forward switching hydraulic pressure, the backward hydraulic pressure is output from the reverse valve to establish the reverse shift stage, and (h) both the forward switching hydraulic pressure and the reverse switching hydraulic pressure stop outputting. As a result, both the forward hydraulic pressure and the reverse hydraulic pressure are in an output stop state, and a neutral for interrupting power transmission is established, and (i) the forward switching hydraulic pressure and the reverse hydraulic pressure are established. May conversion hydraulic pressure is outputted together, the neutral the forward hydraulic and the reverse hydraulic pressure becomes both an output stop state is characterized in that is established.

According to a second aspect of the invention, in the hydraulic control device for an automatic transmission for a vehicle according to the first aspect of the invention, (a) the forward switching device outputs the forward switching hydraulic pressure when the forward switching signal is OFF. The reverse switching device is characterized in that the reverse switching hydraulic pressure is output when the reverse switching signal is ON.

  In the hydraulic control device according to the first aspect of the present invention, since the operating states of the forward switching device and the reverse switching device are different between the forward shift stage and the reverse shift stage, an electrical failure (disconnection or short circuit) of the forward switch signal or the reverse switch signal is caused. ) And the like, and only one of the forward switching device and the reverse switching device fails, there is no fear that the forward / reverse movement will change, and a fail-safe measure will be facilitated. Further, in the present invention, since the forward / reverse switching can be performed by the two switching devices and the two valves, the device is simple and inexpensive.

In addition, even if one of the forward switching device and the reverse switching device fails, the operating state of the other switching device is switched by the driver's switch operation, etc. Therefore, the minimum necessary traveling such as limp home can be ensured. Further, when the forward switching hydraulic pressure is output from the forward switching device, the reverse valve is in the output stop state, and when the reverse switching hydraulic pressure is output from the reverse switching device, the forward valve is in the output stopped state. There is no possibility that both the forward hydraulic pressure and the reverse hydraulic pressure are output and the automatic transmission is locked.

In the second aspect of the invention, when the vehicle is traveling forward, the forward switching signal is turned off and the forward switching hydraulic pressure is output from the forward switching device, and the reverse switching signal is turned off and the backward switching hydraulic pressure is output. By stopping, the forward hydraulic pressure is output from the forward valve, so that both the forward switching signal and the reverse switching signal are OFF, reducing the current consumption and improving the fuel consumption. In addition, the most likely failure is when the power is cut off due to disconnection or poor contact, but in the present invention, when the forward switching signal or the backward switching signal is turned OFF due to an electrical failure, Reverse travel is not possible, but forward travel and neutral are possible, so that travel in an emergency such as a limp home is easier than when reverse travel is possible.

  The present invention is preferably applied to a planetary gear type automatic transmission that shifts by engagement and release of a hydraulic friction engagement device such as a clutch or a brake. It can be applied to various automatic transmissions. In general, a plurality of shift speeds with different gear ratios are established in the forward shift speed, but it is sufficient that at least forward / reverse shift is switched, and a plurality of forward shift speeds are not necessarily required, and the speed ratio is changed. A stepped transmission or a continuously variable transmission may be provided separately.

  The forward switching device and the reverse switching device are, for example, a solenoid valve that opens and closes an oil passage when the solenoid is excited by an exciting current as a forward switching signal or a backward switching signal. Excitation means ON of the forward switching signal and reverse switching signal, and non-excitation of the solenoid due to non-energization of the excitation current means OFF of the forward switching signal and reverse switching signal. The forward switching signal and the backward switching signal are configured to be output in response to a selection operation of a range selection switch that can select, for example, the forward travel range, the reverse travel range, and the neutral.

Further, the forward valve and the reverse valve are normally held in an output stop state by an urging means such as a spring or hydraulic pressure, and forward switching hydraulic pressure, reverse switching hydraulic pressure, etc. are applied in the opposite direction to the urging means. Thus, the valve body such as the spool is moved and switched to the output state. Further, for example, the backward switching hydraulic pressure is introduced into the forward valve and the forward switching hydraulic pressure is introduced into the backward valve so as to bias the valve body in the same direction as the biasing means .

The setting, when the output stop forward movement switching hydraulic and reverse switching hydraulic pressure together and, in the case of forward movement switching hydraulic and reverse switching hydraulic both outputs, both while the neutral is established, either one as a normal neutral during However, it is desirable that the other neutral is established when the neutral at the normal time is not possible due to the failure.

In the second invention, the forward switching signal is forward movement switching hydraulic pressure at the time of OFF is outputted, but reverse switching hydraulic when reverse switching signal is ON is output, when the implementation of the first invention, the addition (a ) The forward switching hydraulic pressure is output when the forward switching signal is ON, and the reverse switching hydraulic pressure is output when the reverse switching signal is ON. (B) The forward switching hydraulic pressure is output when the forward switching signal is OFF. The reverse switching hydraulic pressure is output when the reverse switching signal is OFF, or (c) the forward switching hydraulic pressure is output when the forward switching signal is ON and the reverse switching hydraulic signal is output when the reverse switching signal is OFF. Three combinations of switching oil pressure output are possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 (a) is a skeleton diagram of a vehicular automatic transmission 10 to which the present invention is applied, and FIG. 1 (b) is an operation table for explaining engaging elements when a plurality of shift stages are established. The automatic transmission 10 for a vehicle is for horizontal installation of an FF vehicle or the like, and includes a first transmission unit 14 mainly composed of a single pinion type first planetary gear device 12 and a single pinion type second gear. The second transmission unit 20 mainly composed of the planetary gear unit 16 and the double pinion type third planetary gear unit 18 is provided on the coaxial line, and the rotation of the input shaft 22 is shifted and output from the output gear 24. . The input shaft 22 corresponds to an input member, such as a turbine shaft of a torque converter that is rotationally driven by an engine 48 (see FIG. 2) as a travel drive source, and the output gear 24 corresponds to an output member. The left and right drive wheels are rotationally driven via the differential gear device. The automatic transmission 10 for a vehicle is configured substantially symmetrically with respect to the center line, and the lower half of the center line is omitted in FIG.

  The first planetary gear unit 12 constituting the first transmission unit 14 includes three rotating elements, that is, a sun gear S1, a planetary carrier CA1, and a ring gear R1, and the sun gear S1 is connected to the input shaft 22 to rotate. When the ring gear R1 is driven and fixed to the case 26 through the third brake B3 so as not to rotate, the planetary carrier CA1 is decelerated and rotated with respect to the input shaft 22 as an intermediate output member. Further, the second planetary gear device 16 and the third planetary gear device 18 constituting the second transmission unit 20 are partially connected to each other to constitute four rotating elements RM1 to RM4. Specifically, the first rotating element RM1 is configured by the sun gear S3 of the third planetary gear unit 18, and the ring gear R2 of the second planetary gear unit 16 and the ring gear R3 of the third planetary gear unit 18 are connected to each other to perform the second rotation. The element RM2 is configured, and the planetary carrier CA2 of the second planetary gear unit 16 and the planetary carrier CA3 of the third planetary gear unit 18 are connected to each other to configure the third rotating element RM3, and the sun gear S2 of the second planetary gear unit 16 is configured. Thus, the fourth rotation element RM4 is configured. In the second planetary gear device 16 and the third planetary gear device 18, the planetary carriers CA2 and CA3 are made of a common member, and the ring gears R2 and R3 are made of a common member, and The planetary gear of the two planetary gear unit 16 is a Ravigneaux type planetary gear train that also serves as the second planetary gear of the third planetary gear unit 18.

  The first rotating element RM1 (sun gear S3) is selectively coupled to the case 26 by the first brake B1 and stopped rotating, and the second rotating element RM2 (ring gears R2, R3) is selectively selected by the second brake B2. The fourth rotation element RM4 (sun gear S2) is selectively connected to the input shaft 22 via the first clutch C1, and the second rotation element RM2 (ring gears R2, R3) is connected to the case 26 and stopped. Is selectively connected to the input shaft 22 via the second clutch C2, and the first rotating element RM1 (sun gear S3) is integrally connected to the planetary carrier CA1 of the first planetary gear unit 12 as an intermediate output member. The third rotation element RM3 (planetary carriers CA2, CA3) is integrally connected to the output gear 24 to output rotation.The first brake B1 to the third brake B3, the first clutch C1, and the second clutch C2 are all multi-plate hydraulic friction engagement devices that are frictionally engaged by a hydraulic cylinder.

  Then, the solenoid valve SR, SD (see FIG. 2) is switched between excitation and non-excitation according to the shift range R, N, D selected by the driver, so that the D range pressure PD for forward travel, reverse travel The output of the R range pressure PR is turned on and off, and the clutches C1 and C2 and the brakes B1 to B3 are engaged and released as shown in FIG. Is established. In the forward shift speed of the D range, the engagement and disengagement states of the clutches C1 and C2 and the brakes B1 to B3 are changed by switching between excitation and non-excitation of the solenoid valves SL1 to SL5 (see FIG. 2), The first shift speed “1st” to the sixth shift speed “6th” having different ratios are established. In the operation table of FIG. 1 (b), “◯” indicates engagement, and “×” indicates disengagement, and the gear ratios of the respective gear stages are the first planetary gear unit 12, the second planetary gear unit 16, and the first planetary gear unit 16. It is appropriately determined by the gear ratios ρ1, ρ2, and ρ3 of the three planetary gear unit 18.

FIG. 2 is a block diagram illustrating a control system provided in the vehicle for controlling the automatic transmission 10 and the engine 48 of FIG. 1. The operation amount A _CC of the accelerator pedal 50 is determined by the accelerator operation amount sensor 51. It is to be detected. The accelerator pedal 50 is largely depressed according to the driver's required output amount, and corresponds to an accelerator operation member, and the accelerator pedal operation amount A _CC corresponds to an output request amount. The intake pipe of the engine 48 is provided with an electronic throttle valve 56 that has an opening angle (opening) θ _TH corresponding to the accelerator pedal operation amount A _CC by a throttle actuator 54. Further, in the bypass passage 52 for bypassing the electronic throttle valve 56 for idle rotation speed control, the intake air amount when the electronic throttle valve 56 is fully closed is controlled in order to control the idle rotation speed NE _IDL of the engine 48. An ISC (idle rotational speed control) valve 53 is provided. In addition, an intake air amount sensor 60 for detecting an intake air quantity Q of the engine rotational speed sensor 58, an engine 48 for detecting the rotational speed NE of the engine 48, the intake for detecting the temperature T _A of intake air An air temperature sensor 62, a throttle sensor 64 with an idle switch for detecting the fully closed state (idle state) of the electronic throttle valve 56 and its opening θ _TH , vehicle speed V (corresponding to the rotational speed N _OUT of the output gear 24) a vehicle speed sensor 66 for detecting a coolant temperature sensor 68 for detecting the cooling water temperature T _W of the engine 48, a brake switch 70 for detecting the operation of the brake, the range selector switch 74 is selectively operated by a driver, turbine speed NT turbine speed sensor 76 for detecting (= rotational speed N _iN of the input shaft 22), the hydraulic control Such as AT oil temperature sensor 78 for detecting the the temperature of the hydraulic fluid of the road within 98 AT oil temperature T _OIL is provided with, from the sensors, the engine rotational speed NE, the intake air quantity Q, intake air temperature Signals representing T _A , throttle valve opening θ _TH , vehicle speed V, engine cooling water temperature T _W , brake operating state BK, selected shift range P _SH , turbine rotational speed NT, AT oil temperature T _OIL are electronically controlled. The apparatus 90 is supplied. The range selection switch 74 is for electrically selecting any one of the D range for establishing the forward shift stage, the R range for establishing the reverse shift stage, and the N range for interrupting power transmission, and corresponds to a shift lever. It is.

  The electronic control unit 90 includes a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU uses a temporary storage function of the RAM, and signals according to a program stored in the ROM in advance. By performing the processing, output control of the engine 48, shift control of the automatic transmission 10, and the like are executed, and the engine control and the shift control are divided as necessary.

  FIG. 3A is a hydraulic circuit diagram for switching the vehicle automatic transmission 10 to a forward shift stage, a reverse shift stage, and a neutral that cuts off power transmission in accordance with the selection operation of the range selection switch 74. In addition to the electronic control unit 90 and solenoid valves SR and SD, a reverse valve 100 that outputs an R range pressure PR as a reverse hydraulic pressure and a forward valve 102 that outputs a D range pressure PD as a forward hydraulic pressure are provided. Yes. The solenoid valve SR corresponds to a reverse switching device. In this embodiment, a normally closed (N / C) type is used, and an excitation current SSR is supplied from the electronic control device 90 as a reverse switching signal. The reverse switching hydraulic pressure PSR is output, and when the supply of the excitation current SSR is stopped, the output of the reverse switching hydraulic pressure PSR is stopped. The solenoid valve SD corresponds to a forward switching device. In this embodiment, a normally open (N / O) type is used, and an excitation current SSD is supplied from the electronic control device 90 as a forward switching signal. The output of the forward switching hydraulic pressure PSD is stopped, and when the supply of the excitation current SSD is stopped, the forward switching hydraulic pressure PSD is output.

  The reverse valve 100 is normally held in an output stop state in which the output of the R range pressure PR is stopped by the spring 104. However, when the reverse switching hydraulic pressure PSR is supplied from the solenoid valve SR, the biasing force of the spring 104 is maintained. The spool is moved against this, and the output state is switched to output the line hydraulic pressure PL as the R range pressure PR. Further, the forward switching hydraulic pressure PSD output from the solenoid valve SD is introduced into the reverse valve 100 through the oil passage 106, and the spool is biased in the same direction as the biasing direction of the spring 104, so Regardless of the presence or absence of the switching hydraulic pressure PSR, the output stop state in which the output of the R range pressure PR is stopped is maintained.

  The forward valve 102 is configured in the same manner as the reverse valve 100, and is normally held in an output stop state in which the output of the D range pressure PD is stopped by the spring 108. However, the forward switching hydraulic pressure PSD is supplied from the solenoid valve SD. Is supplied, the spool is moved against the urging force of the spring 108, and the output state is switched to output the line oil pressure PL as the D range pressure PD. Further, the reverse switching hydraulic pressure PSR output from the solenoid valve SR is introduced through the oil passage 110, and the spool is biased in the same direction as the biasing direction of the spring 108. Regardless, the output stop state in which the output of the D range pressure PD is stopped is maintained.

  FIG. 3B shows the range selected by the range selection switch 74, the excitation “◯”, the non-excitation “×” of the solenoid valves SR and SD, the output “◯” of the reverse switching hydraulic pressure PSR and the forward switching hydraulic pressure PSD, and the output. The output of the stop “×” and the R range pressure PR and D range pressure PD is shown together. The solenoid valves SR and SD are energized and de-energized in the shift range selected by the range selection switch 74. Accordingly, the excitation currents SSR and SSD supplied from the electronic control unit 90 are switched by ON (energized) and OFF (non-energized). Note that “N (failure)” at the bottom of FIG. 3 (b) is established when the neutral “N” during normal operation is not possible due to a failure such as disconnection or short-circuit. Specifically, the solenoid valve SR is This is established when the motor cannot be de-energized by failing ON or when the solenoid valve SD is failing by failing OFF.

  4 to 7 are diagrams for specifically explaining each shift range and N (fail), and each dotted line represents an output stop state. FIG. 4 shows the case where the R range is selected by the range selection switch 74. The electronic control unit 90 outputs the excitation current SSR to excite the solenoid valve SR, and outputs the excitation current SSD to turn on the solenoid valve SD. Excited. As a result, the reverse switching hydraulic pressure PSR is output, the output of the forward switching hydraulic pressure PSD is stopped, and the reverse switching hydraulic pressure PSR switches the reverse valve 100 to the output state, whereby the R range pressure PR is output and the automatic shift is performed. The reverse gear is established in the machine 10.

  FIG. 5 shows the case where the N range is selected by the range selection switch 74. The electronic control unit 90 stops the output of the excitation current SSR to de-energize the solenoid valve SR and outputs the excitation current SSD. Energize solenoid valve SD. As a result, the output of both the reverse switching hydraulic pressure PSR and the forward switching hydraulic pressure PSD is stopped, the reverse valve 100 and the forward valve 102 are both held in the output stopped state, and the R range pressure PR and D range pressure PD are both Is not output, and the automatic transmission 10 is set to a neutral position that interrupts power transmission.

  FIG. 6 shows the case where the D range is selected by the range selection switch 74, and the electronic control unit 90 stops both the output of the excitation currents SSR and SSD and de-energizes both the solenoid valves SR and SD. As a result, the output of the reverse switching hydraulic pressure PSR is stopped and the forward switching hydraulic pressure PSD is output. When the forward switching hydraulic pressure PSD is switched to the output state, the D range pressure PD is output and the automatic shift is performed. The machine 10 is established at the forward shift speed.

  FIG. 7 shows a case where the automatic transmission 10 is set to neutral when the solenoid valve SR fails to be de-energized due to ON failure, or when the solenoid valve SD fails to be excited due to OFF failure. When SR is in an on-fail state, the output of the other excitation current SSD is stopped, while when the solenoid valve SD is in an off-failure state, the other excitation current SSR is output. Thus, in any case, the solenoid valve SR is excited and the solenoid valve SD is de-energized, and both the reverse switching hydraulic pressure PSR and the forward switching hydraulic pressure PSD are output, and the reverse valve 100 and the forward valve 102 are Both are held in an output stopped state, and neither the R range pressure PR nor the D range pressure PD is output, and the automatic transmission 10 is set to neutral.

  As described above, in the hydraulic control apparatus according to the present embodiment, the operating states of the solenoid valves SR and SD, that is, the output of the excitation currents SSD and SSR, in the D range that establishes the forward shift stage and the R range that establishes the reverse shift stage. The states are all different. That is, the solenoid valves SR and SD are both de-energized in the D range, while the solenoid valves SR and SD are both excited in the R range. For this reason, if only one of them fails due to a disconnection or a short circuit, there is no fear that the output hydraulic pressures PR and PD change and the forward / backward movement is switched, and a fail-safe measure is facilitated.

  In addition, since the operating states of the solenoid valves SR and SD are different between the D range and the R range, even if one of the solenoid valves SR and SD fails, the other solenoid can be operated by operating the range selection switch 74 or the like. By switching the operating state of the valve SD or SR, either one of the forward and backward shift stages is established and neutral N or N (fail) is possible. Can be secured. In particular, the most probable failure is when the solenoid valves SR and SD fail OFF (de-energized) due to disconnection or poor contact. In this embodiment, the solenoid valves SR and SD are in the D range. Since both are originally non-excited, the forward shift stage is established in the D range even if either one of them fails OFF, and emergency travel such as limp home can be easily performed by forward travel.

  Further, since the solenoid valves SR and SD are both non-excited in the forward traveling D range where the vehicle is used most frequently, the current consumption is reduced and the fuel consumption is improved.

  Further, when the forward switching hydraulic pressure PSD is output from the forward solenoid valve SD, the reverse valve 100 is held in an output stop state in which the output of the R range pressure PR is stopped regardless of the presence or absence of the reverse switching hydraulic pressure PSR. When the reverse switching hydraulic pressure PSR is output from the reverse solenoid valve SR, the control valve 102 is maintained in the output stop state in which the output of the D range pressure PD is stopped regardless of the presence or absence of the forward switching hydraulic pressure PSD. Thus, there is no possibility that the R range pressure PR and the D range pressure PD are both output and the automatic transmission 10 is locked.

  Further, since the four solenoid valves SR, SD and the reverse valve 100 and the forward valve 102 can be used to switch the forward / reverse movement, the apparatus is simple and inexpensive.

  In the above embodiment, a normally closed type is used as the solenoid valve SR, and a normally open type is used as the solenoid valve SD. Therefore, in the D range, the solenoid valves SR and SD are both de-energized. Specifically, it is sufficient that the operating states of the solenoid valves SR and SD are different between the D range and the R range, and it is possible to configure as shown in (a) to (c) of FIG. is there. 8A shows a normally closed (N / C) type solenoid valve SR that outputs a reverse switching hydraulic pressure PSR when the excitation current SSR is ON, and a forward switching hydraulic pressure PSD when the excitation current SSD is ON. When normally closed (N / C) type solenoid valve SD is used, (b) shows normally open (N / O) that outputs reverse switching hydraulic pressure PSR when excitation current SSR is OFF. When a normally open (N / O) type solenoid valve SD that outputs a forward switching hydraulic pressure PSD when the exciting current SSD is OFF is used, (c) indicates that the exciting current SSR is Normally open (N / O) type solenoid valve SR that outputs reverse switching hydraulic pressure PSR when OFF, and excitation current S D is a case where the normally-closed (N / C) type solenoid valve SD for outputting a forward movement switching hydraulic PSD when ON was used.

  As mentioned above, although the Example of this invention was described in detail based on drawing, these are one embodiment to the last, and this invention is implemented in the aspect which added the various change and improvement based on the knowledge of those skilled in the art. be able to.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the automatic transmission for vehicles provided with the hydraulic control apparatus which is one Example of this invention, (a) is a skeleton diagram, (b) is the operation | movement table | surface for establishing each gear stage. It is a block diagram explaining the control system of the vehicle drive device containing the automatic transmission of FIG. FIG. 2 is a diagram for explaining a hydraulic control device for switching between forward and backward movements of the automatic transmission of FIG. 1, (a) is a hydraulic circuit diagram, and (b) is a diagram for explaining an operating state of each part in each shift range. In FIG. 3, it is a figure explaining the operation state of each part concretely when R range is selected. In FIG. 3, it is a figure explaining the operation state of each part concretely when the N range is selected. In FIG. 3, it is a figure explaining the operating state of each part concretely when D range is selected. In FIG. 3, it is a figure explaining concretely the operation state of each part of neutral "N (failure)" established at the time of a failure. It is a figure explaining the other Example of this invention, and is a figure equivalent to (b) of FIG.

Explanation of symbols

  10: Automatic transmission 90: Electronic control device 100: Reverse valve 102: Forward valve SR: Solenoid valve (reverse switching device) SD: Solenoid valve (forward switching device) SSR: Excitation current (reverse switching signal) SSD: Excitation Current (forward switching signal) PSR: Reverse switching hydraulic pressure PSD: Forward switching hydraulic pressure PR: R range pressure (reverse hydraulic pressure) PD: D range pressure (forward hydraulic pressure)

Claims (2)

In a hydraulic control device for a vehicle automatic transmission in which a forward shift stage is established by forward hydraulic pressure and a reverse shift stage is established by reverse hydraulic pressure,
A forward valve for switching between output and output stop of the forward hydraulic pressure;
A reverse valve for switching between output and output stop of the reverse hydraulic pressure;
A forward switching device that switches the forward valve to an output state by outputting a forward switching hydraulic pressure when the forward switching signal is ON or OFF;
A reverse switching device for switching the reverse valve to an output state by outputting a reverse switching hydraulic pressure when the reverse switching signal is ON or OFF;
And the forward valve is held in the output stop state of the forward hydraulic pressure regardless of the presence of the forward switching hydraulic pressure when the reverse switching hydraulic pressure is output, and the reverse valve is When the switching hydraulic pressure is output, regardless of the presence of the reverse switching hydraulic pressure, it is held in the output stop state of the reverse hydraulic pressure,
When the forward switching hydraulic pressure is output and the reverse switching hydraulic pressure is stopped, the forward hydraulic pressure is output from the forward valve to establish the forward shift stage,
When the reverse switching hydraulic pressure is output and the forward switching hydraulic pressure is stopped, the reverse hydraulic pressure is output from the reverse valve to establish the reverse gear.
By stopping the output of both the forward switching hydraulic pressure and the reverse switching hydraulic pressure, both the forward hydraulic pressure and the reverse hydraulic pressure are in the output stop state, and a neutral for interrupting power transmission is established,
The automatic transmission for vehicles is characterized in that both the forward switching hydraulic pressure and the reverse switching hydraulic pressure are output, and both the forward hydraulic pressure and the reverse hydraulic pressure are in an output stopped state and the neutral is established. Hydraulic control device. The forward switching device outputs the forward switching hydraulic pressure when the forward switching signal is OFF,
The hydraulic control device for an automatic transmission for a vehicle according to claim 1 , wherein the reverse switching device outputs the reverse switching hydraulic pressure when the reverse switching signal is ON.

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