JP2666645B2 - Hydraulic control unit for shift-by-wire automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device for an automatic transmission, and more particularly to a hydraulic control device for a shift-by-wire automatic transmission configured to switch a traveling range based on an electric signal.

[0002]

2. Description of the Related Art As is well known, an automatic transmission for a vehicle is configured to perform a shift by changing the state of engagement / disengagement of a friction engagement device such as a clutch or a brake by hydraulic pressure. The determination of the shift is generally made based on the engine load represented by the throttle opening and the vehicle speed.
Shifting based on such a running state is performed for a plurality of forward gears, but a running range such as a reverse range or a neutral range in which engine braking is effective at a middle to low speed is conventionally selected by a shift lever. Was manually operated.

On the other hand, recently, there has been proposed an automatic transmission configured to electrically select a traveling range by operating a switch. This is basically configured to drive a valve for switching a travel range by operating a predetermined actuator by operating a switch. In this type of apparatus, a means for dealing with an abnormality in an electric system or a valve mechanism, that is, a fail-safe means is generally provided. example
If the JitsuHiraku Akira 62-184249 discloses a device provided with the emergency valve is described. The device described in this publication is configured to execute a shift by operating a rotary valve by a motor,
An emergency valve is provided in parallel with the rotary valve, and when an abnormality occurs in the rotary valve, the supply of hydraulic pressure to the rotary valve is shut off, and the hydraulic pressure is applied to a specific frictional engagement device via the emergency valve. Is supplied.

[0004]

In the conventional apparatus provided with the above-described emergency valve, even if the rotary valve for performing the shift operation does not operate normally, the hydraulic pressure is not reduced via the emergency valve. A predetermined gear position can be set by engaging a specific frictional engagement device supplied with. However, the gear position that can be set in this way is a specific one of the forward gear positions. Therefore, even if the vehicle can travel forward, it can be driven according to various conditions such as road conditions. However, there is a problem that the method is not practical.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and sets a plurality of forward gears or forward gears and neutral even if an abnormality occurs in an electrically controlled range switching mechanism. It is an object of the present invention to provide a hydraulic control device capable of performing the following.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a range switch for selectively outputting a hydraulic pressure for setting a plurality of forward gears and a hydraulic pressure for setting a reverse gear. A hydraulic control device for a shift-by-wire automatic transmission that controls a mechanism based on an electric signal, wherein the range switching mechanism selectively outputs hydraulic pressure from at least two output ports under the control of an electric signal. and 1 of the range switching valve, when said at least the first range switching valve
Based on the outputs and the electric signal switches to set a plurality of ranges including a forward range to set the reverse range and the forward stage for setting the reverse stage two output ports or we output the oil pressure A second range switching valve that is switch-controlled, and selectively shuts off the supply of a hydraulic pressure output from the second range switching valve to a friction engagement device for setting a reverse stage. Is provided.

[0007]

In the present invention, the hydraulic pressure for setting the forward gear or the hydraulic pressure for setting the reverse gear is output by controlling the range switching mechanism based on the electric signal. Output is cut off to neutral. In this range switching mechanism, the hydraulic pressure supplied to the second range switching valve from one of the ports of the first range switching valve is set such that the reverse range is set by the second range switching valve or the other. And the hydraulic pressure supplied to the second range switching valve from the other port of the first range switching valve sets another range by the second range switching valve. And output. Even if the first range switching valve of these two range switching valves or the hydraulic mechanism or the electric system for operating the first range switching valve is abnormal and the hydraulic pressure is output only from the one port,
A reverse range and another range can be set by the second range switching valve, and when the hydraulic pressure is output only from the other port, the range can be switched to the other at least two ranges. Even if an abnormality occurs such that the second range switching valve is not switched, at least two ranges can be selected and set by switching the first range switching valve. If the first range switching valve has been switched to the state of setting the reverse range, the supply of hydraulic pressure to the friction engagement device for setting the reverse speed is controlled by the reverse speed control valve. Blocking and setting the reverse gear is prohibited.

[0008]

Next, an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 and 2 are hydraulic circuit diagrams showing a main part of a hydraulic control device according to the present invention. The hydraulic control device shown here is intended for, for example, a shift-by-wire automatic transmission shown in FIG. . The automatic transmission A shown in FIG. 3 has a plurality of transmission mechanisms including a torque converter 2 having a lock-up clutch 1, a second transmission section 3 having a set of planetary gear mechanisms, and two sets of planetary gear mechanisms. A first transmission unit 4 for setting a forward speed and a reverse speed is provided.

The second speed change section 3 performs two-stage switching between high and low, and has a carrier 5 of the planetary gear mechanism.
Are connected to a turbine runner 6 of the torque converter 2, and a clutch C0 and a one-way clutch Fo are provided between the carrier 5 and the sun gear 7 in a mutually parallel relationship. H
u is provided with a brake B0.

The sun gears 8 and 9 in each planetary gear mechanism of the first transmission unit 4 are provided on a common sun gear shaft 10, and the left side (front side) of the first transmission unit 4 in the drawing.
Gear 11 and second transmission portion 3 in the planetary gear mechanism of
A first clutch C1 is provided between the sun gear shaft 10 and the ring gear 12 of the second transmission unit 3, and a second clutch C2 is provided between the sun gear shaft 10 and the ring gear 12 of the second transmission unit 3. The carrier 13 of the planetary gear mechanism on the left side in the figure and the ring gear 14 of the planetary gear mechanism on the right side (rear side) in the first transmission portion 4 are integrally connected, and the output shaft is connected to the carrier 13 and the ring gear 14. 15 are connected.

A first brake B1 as a band brake is provided to stop the rotation of the sun gear shaft 10,
More specifically, the first one-way clutch F1 and the second brake B2 are arranged in series between the sun gear shaft 10 and the housing Hu and are provided on the outer peripheral side of the clutch drum of the second clutch C2. A second one-way clutch F2 and a third brake B3 are arranged in parallel between the carrier 16 and the housing Hu in the rear planetary gear mechanism.

The hydraulic control device 17 for supplying and discharging the hydraulic pressure to the clutches C0, C1, C2 and the brakes B0, B1, B2, B3 is used to execute the first to fourth speed shifts. The first and second solenoid valves S1,
S2, a linear solenoid valve SLU for controlling the lock-up clutch 1, and third and fourth solenoid valves S3 and S4 for switching the traveling range. These solenoid valves S1, S2, SL
In order to control the first and second solenoid valves S1 and S2 and the linear solenoid valve SLU among U, S3 and S4, a shift electronic control unit (hereinafter referred to as a shift EC) is used.
U), and a traveling range switching electronic control device (hereinafter referred to as a range switching E) for controlling the third and fourth solenoid valves S3 and S4 to switch the traveling range.
CU) 19 are provided. Each of these EU
C18 and C19 are mainly composed of a central processing element, a storage element, and an input / output interface.
Similar to the conventional ECU, signals such as a throttle opening signal, a vehicle speed signal, a pattern select signal, an engine coolant temperature signal, and a brake signal are input to the shift ECU 18, and the shift ECU 18 receives these input signals. And calculating the gear position to be set based on the shift map stored in advance and outputting a signal to the first and second solenoid valves S1 and S2 to set the gear position.
A signal is output to the linear solenoid valve SLU.

On the other hand, the range switching ECU 19 includes:
Range selection switch 2 for selecting parking (P) range, reverse (R) range, neutral (N) range, drive (D) range, S range, and L range
0 is connected, and the range switching ECU 19 controls the third and fourth solenoid valves S3 and S4 to turn on and off so as to set the travel range selected by the range selection switch 20, and simultaneously shifts the range position signal. ECU1
8 and a range display (not shown). A shift signal indicating a shift speed is input from the shift ECU 18 to the range switching ECU 19.

The hydraulic control device 17 is shown in FIGS.
The hydraulic circuit shown in FIG. Note that the circled numbers in FIGS. 1 and 2 indicate that the lines with the same numbers are connected to each other. As shown in FIG. 1, two range switching valves 200 and 300 for switching a traveling range are provided. The first range switching valve 200 includes a spool 201 having four lands.
And a spring 20 provided at one end (lower end in the figure)
The third solenoid valve S3 is connected to a control port 203 at the end opposite to the end where the spring 202 is provided. The third solenoid valve S3 supplies and discharges a line pressure PL obtained by regulating oil pressurized by the hydraulic pump 100 by the primary regulator valve 101 to the control port 203, and is in an off state. To generate a line pressure PL at the control port 203, and open the drain port to release the pressure from the control port 203 in the on state. And this first range switching valve 2
00 is an input port to which the line pressure oil passage 102 is connected when the spool 201 is pushed by the spring 202 and is at the position shown in the right half of FIG. When the second solenoid valve 204 is connected to the first output port 205 and the second output port 206 is communicated to the drain port 207 and the third solenoid valve S3 is off, the spool 201
Is located at the position shown in the left half of FIG. 1 against the elastic force of the spring 202, the input port 204 communicates with the second output port 206 and the first output port 205 communicates with the drain port 208. It has become.

The second range switching valve 300 has a spool 301 having six lands and a spring 302 disposed at one end of the spool 301. The spring 302 is formed at an end opposite to the spring 302. The fourth solenoid valve S4 is connected to the control port 303.
The fourth solenoid valve S4 is for supplying and discharging the line pressure PL to and from the control port 303. As in the case of the third solenoid valve S3, the drain port is closed in the off state and the line pressure is supplied to the control port 303. PL is generated, and the drain port is opened to release the pressure from the control port 303 in the ON state. This second
The range switching valve 300 includes the first range switching valve 20.
0, a first input port 304 connected to the first output port 205, and a second input port 305 connected to the second output port 206 of the first range switching valve 200, and an R range port 306; D
It has three output ports, a range port 307 and an engine brake port 308. When the spool 301 is at the position shown in the right half of FIG. 1 with the fourth solenoid valve S4 being in the ON state, the second range switching valve 300 is connected to the first input port 304 and the R range port 306. And the second input port 3
05 and the engine brake port 308, and the D range port 307 and the drain port 309. When the fourth solenoid valve S4 is off and the spool 301 is at the position shown in the left half of FIG. 1, the first input port 304 communicates with the D range port 307, and the R range port The 306 and the engine brake port 308 communicate with the drain ports 310 and 309, respectively.

The aforementioned R range port 306 is connected to the reverse stage control valve 400. The reverse speed control valve 400 is a valve that selectively shuts off the hydraulic pressure applied to the third brake B3 to be engaged to set the reverse speed and selectively inhibits the reverse speed. The spring 402 is disposed, and the spring 402
A control port 404 for applying a hydraulic pressure so as to push the spool 401 toward the hold port 403 is formed at the end where the is disposed. The R range port 306 is connected to the control port 404 and the input port 405, the hold port 403 is connected to the second solenoid valve S2, and the input port 405 and the drain port 406 are switched to communicate with each other. The port 407 is connected to the third brake B3 via a check ball valve 103 having two input ports and one output port.

The D range port 307 and the engine brake port 308 of the second range switching valve 300
Are connected to respective input ports of the check ball valve 104 having two input ports and one output port. And this check ball valve 10
The fourth output port is connected to the first clutch C1.

Further, a 1-2 shift valve 500, a 2-3 shift valve 600, a 3-4 shift valve 700, and a cutoff valve 800 are provided. These valves are used to execute a shift between the first speed and the fourth speed in the forward gear, and have basically the same configuration as those conventionally known. That is, 1-2 shift valve 500
Has a spring 502 disposed at one end of a spool 501 having four lands, a hold port 503 formed at an end where the spring 502 is disposed, and a control port at an end opposite to the hold port 503. The port 504 is formed, and the control port 5
04 is connected to a second solenoid valve S2. The second solenoid valve S2 is for supplying and discharging the line pressure PL from the line pressure oil passage 102.
In the on state, the drain port is opened to release the pressure, and in the off state, the drain port is closed to generate a line pressure PL at the control port 504 of the 1-2 shift valve 500 and the hold port 403 of the reverse stage control valve 400. It has become. When the second solenoid valve S2 is turned on, or when the line pressure PL acts on the hold port 503, the 1-2 shift valve 5 is turned on.
00 is located as shown in the left half of FIG. 2 so that the first input port 505 communicates with the first brake port 506 and the check ball valve 1
Second input port 507 connected to output port 04
Communicates with the second brake port 508, the third input port 509 is closed, and the third brake port 51
0 communicates with the drain port. Hold port 50
3 and the second solenoid valve S2 is turned off, whereby the spool 501 of the 1-2 shift valve 500 is positioned as shown in the right half of FIG. 2, and as a result, the first input port 505 and Second input port 507
Is closed, and the third input port 509 communicates with the third brake port 510. And the first brake port 5
06 is connected to the cutoff valve 800, the second brake port 508 is connected to the second brake B2, and the third brake port 510 is connected to the third brake B3 via the check ball valve 103.

The 2-3 shift valve 600 is switched by a first solenoid valve S1. A spring 602 is disposed at one end of a spool 601 having six lands.
02, a control port 603 is formed at the end opposite to the first solenoid valve S.
1 is connected. This first solenoid valve S1
Represents the hydraulic pressure sent from the D range port 307 of the second range switching valve 300 or the engine brake port 308 via the check ball valve 104,
This is for supplying and discharging to and from the control port 603. When the drain port is closed in the off state, a line pressure PL is generated in the control port 603, and in the on state, the drain port is opened to discharge from the control port 603. Pressure. Then, the line pressure PL acts on the control port 603 of the 2-3 shift valve 600 and the spool 60
1 is pushed down to the position shown in the left half of FIG. 2, the first input port 604 to which the line pressure oil passage 102 is connected communicates with the clutch port 605, and the engine brake of the second range switching valve 300 Port 3
08 is connected to the hold output port 607, and the third input port 608 connected to the engine brake port 308 is closed. When the pressure is released from the control port 603 and the spool 601 is pushed up to the position shown in the right half of FIG.
The first input port 604 communicates with the hold output port 607, the second input port 606 communicates with the first brake port 609, and the third input port 608 communicates with the second brake port 610. Of these ports, the first brake port 609 is connected to the first input port 505 of the 1-2 shift valve 500, and the clutch port 60
5 is connected to a second clutch C2 via a check ball valve 105 having two input ports and one output port.
And hold port 503 of 1-2 shift valve 500
The second brake port 610 is connected to the 1-2 shift valve 5 through the modulator valve 106.
00 is connected to the third input port 509. In addition,
The other input port of the check ball valve 105 is connected to the output port 407 of the reverse stage control valve 400.

The 3-4 shift valve 700 has a spool 701 having four lands and a spring 702 disposed at one end of the spool 701. The 2-3 shift valve is provided at the end where the spring 702 is disposed. Hold port 70 connected to hold output port 607 in 600
3 is formed, and a control port 70 to which the second solenoid valve S2 is connected is provided at an end opposite to the control port 70.
4 are formed. When the pressure is released from the hold port 703 and the line pressure PL is generated in the control port 704, the spool 701 is pushed down to the position shown in the left half of FIG. When the pressure is released from the control port 704, the spool 701 is pushed up to the position shown in the right half of FIG. 2 and the input port 705 is connected to the clutch C0. Connected to the clutch port 707.

The cut-off valve 800 reduces the flow area from the input port 802 to the output port 803 by pushing down the spool 801 to the position shown in the right half of FIG. 2 by increasing the throttle pressure according to the throttle opening. The input port 802 is connected to the 1-2 shift valve 5 via the modulator valve 107.
00 is connected to the first brake port 506. The output port 803 is connected to the first brake B1.

In the automatic transmission having the above-described hydraulic control device, each of the friction engagement devices is controlled by controlling the first to fourth solenoid valves S1 to S4 to be turned on and off as shown in the operation table of FIG. Are engaged or released as shown in the operation table of FIG. In FIG. 4, for the solenoid valve, the mark オ ン indicates ON, the mark X indicates OFF, and the other marks indicate either ON or OFF. For the friction engagement device, ○ indicates engagement, X indicates release, Other marks indicate that either engagement or release may be performed.

As is apparent from FIG. 4, in the hydraulic control apparatus described above, the traveling range is determined by the combination of the on / off states of the third solenoid valve S3 and the fourth solenoid valve S4, and the second solenoid valve S in the R range.
2 can forcibly change to the N range.

When the R range is selected by the range selection switch 20, the third solenoid valve S3 and the fourth solenoid valve S4 are both turned on, and if there is no abnormality, the second solenoid valve S2 is turned off. Therefore, in the first range switching valve 200, the control port 20
3 and the spool 201 is pushed up to the position shown in the right half of FIG. 1, so that the hydraulic pressure is output from the first output port 205. Further, in the second range switching valve 300, the pressure is released from the control port 303 and the spool 301 is pushed up to the position shown in the right half of FIG. 1, so that the hydraulic pressure is supplied from the first output port 205 of the first range switching valve 200. First input port 304 is R range port 30
6 from which hydraulic pressure is supplied to the control port 404 and the input port 405 of the reverse drive control valve 400. In this case, if the second solenoid valve S2 is turned off due to no abnormality, the line pressure PL acts on the hold port 403 of the reverse stage control valve 400. As a result, the input port 405 communicates with the output port 407, from which hydraulic pressure is supplied to the third brake B3 via the check ball valve 103, and the third brake B3 is engaged. Combine. Since the output port 407 of the reverse control valve 400 is connected to the second clutch C2 via another check ball valve 105, hydraulic pressure is also supplied to the second clutch C2 and the second clutch C2 is engaged. That is, the second clutch C2, the third brake B3, and the clutch C0 are engaged to set the reverse speed.

In the state where the reverse gear is set, the third
Solenoid valve S3 or fourth solenoid valve S
4 If there is an abnormality in any of the range switching valves 200 and 300, the second solenoid valve S2 is switched to the ON state. As a result, the pressure is released from the hold port 403 of the reverse drive control valve 400, and the spool 401 is moved by the hydraulic pressure acting on the control port 404 in FIG.
Is pushed down to the position shown in the left half of Accordingly, the input port 405 is closed and the output port 407 is closed.
Communicates with the drain port 406, the second clutch C
The pressure is released from the second and third brakes B3, and these are released. That is, the vehicle is in the neutral state, in other words, the reverse gear is prohibited.

When the N range is selected by the range selection switch 20, the third and fourth solenoid valves S3 and S4 are turned off. Therefore, in the first range switching valve 200, the line oil pressure PL is applied to the control port 203.
Acts to push down the spool 201 to the position shown in the left half of FIG. 1, so that the input port 204 communicates with the second output port 206 and hydraulic pressure is output therefrom.
Since the spool 301 of the range switching valve 300 is pushed down to the position shown in the left half of FIG. 1 by the hydraulic pressure acting on the control port 303, the second input port 305 supplied with the hydraulic pressure from the first range switching valve 200 is closed. Will remain. That is, since the hydraulic pressure is not output from the second range switching valve 300, the first clutch C1 and the third brake B3 are not engaged, so that the output shaft 1
Since no torque is transmitted to 5, the engine is neutral.

When the D range is selected by the range selection switch 20, the third solenoid valve S3 is turned on and the fourth solenoid valve S4 is turned off. Therefore, in the first range switching valve 200, the hydraulic pressure is output from the first output port 205 in the same manner as in the above-described R range, but in the second range switching valve 300, the hydraulic pressure is output as in the above-described N range. Since 301 is pushed down as shown in the left half of FIG. 1, the first input port 304 to which the hydraulic pressure is supplied from the first range switching valve 300 communicates with the D range port 307, from which the hydraulic pressure is output. . Accordingly, the hydraulic pressure is supplied to the first clutch C1 via the check ball valve 104 and is engaged, so that the shift valves 500, 600,
The first to fourth speeds are set according to the state of 700. In that case, the engine brake does not work at the first speed and the second speed. That is, the first brake B1 and the second one-way clutch F which are in a parallel relationship with the first one-way clutch F1.
The third brake B3 in a parallel relationship with the second shift valve 500, as shown in FIGS.
-3 second range switching valve 3 via shift valve 600
When the D range is selected, the engine brake port 308 communicates with the drain port 309, thereby connecting the first brake B1 and the third brake B1.
3 does not engage, and the engine brake does not work.

On the other hand, when the L range is selected by the range selection switch 20, the third solenoid valve S3
Is turned off, and the fourth solenoid valve S4 is turned on. Therefore, in the first range switching valve 200, the hydraulic pressure is output from the second output port 206 in the same manner as in the case of the N range.
As in the case of the range, the spool 301 is lowered to the position shown in the left half of FIG.
A second input port 305, to which hydraulic pressure is supplied from 00, communicates with the engine brake port 308, from which hydraulic pressure is output. Since the engine brake port 308 is connected to the first clutch C1 via the check ball valve 104, it is engaged, and the engine brake port 308 is connected to the first brake B1 and the third brake B3 as described above. 2 shift valve 500 and 2-3
Since the communication is performed via the shift valve 600, when the first solenoid valve S1 is turned on and the second solenoid valve S2 is turned off to set the first speed, the 1-2 shift valve 500 is shown in the right half of FIG. 2 and the 2-3 shift valve 600 is in the state shown in the right half of FIG.
The hydraulic pressure is supplied to the third brake B3 to be engaged.
That is, in setting the first speed, not only the second one-way clutch F2 but also the third brake B3 applies a reaction force to the carrier 16 on the rear side of the first transmission portion 4, so that the engine brake can be applied at the first speed. Can be made.

When the S range is selected by the range selection switch 20, the third solenoid valve S3 is turned on and the fourth solenoid valve S4 is turned off at the first speed, similarly to the D range, so that the second speed and the third speed are set. At a high speed, the third solenoid valve S3 is turned off and the fourth solenoid valve S4 is turned on. Therefore, the first speed in the S range is the same as the state in which the D range is selected, so that the engine brake is not effective at this speed, but the engine brake port 308 is in the second speed as in the case where the L range is selected. When the first solenoid valve S1 and the second solenoid valve S2 are turned on to set the second speed, the hydraulic pressure is supplied to the first brake B1 and the first brake B1 is engaged. That is, in setting the second speed, not only the first one-way clutch F1 but also the first brake B1 applies a reaction force to the sun gear shaft 10, so that the engine brake can be made effective.

As described above, in the range switching mechanism shown in FIG. 1, the range is selected by operating the two range switching valves 200 and 300. Even if the solenoid valves S3 and S4 fail, a plurality of shift speeds and a neutral state can be set, so that a so-called limp form (limp form) is possible. That is, in the case of a failure in which the first range switching valve 200 cannot be switched, the first output port 205 or the second output port 20
6, the oil pressure is output only from the first output port 205.
R range port 3 by the second range switching valve 300
The hydraulic pressure can be output by switching to the 06 and D range ports 307, and the reverse gear is prohibited by the reverse gear control valve 400. When the hydraulic pressure is output only from the second output port 206, the hydraulic pressure can be output from the engine brake port 308 by the second range switching valve 300, or the output of the hydraulic pressure can be stopped. Therefore, since any two ranges of the D range, the S range, the L range, and the N range can be set, the vehicle can travel in a plurality of forward gears.

When the second range switching valve 300 or the fourth solenoid valve S4 for operating the second range switching valve 300 fails and the spool 301 is fixed to the state shown in the left or right half of FIG. 1, the R range and the engine brake range are set. Alternatively, a D range and an N range can be set. That is, when the spool 301 is fixed at the position shown in the right half of FIG. 1, the first range switching valve 200 can be operated to supply hydraulic pressure.
6 and the engine brake port 308 can output hydraulic pressure. In that case, the reverse gear is prohibited by the reverse gear control valve 400. When the spool 301 is fixed at the position shown in the left half of FIG.
00, the D range port 30
Since the hydraulic pressure is output from 7 or no hydraulic pressure is output, the N range can be set. Therefore, in the above-described apparatus, even if a failure occurs in the range switching mechanism, the vehicle can travel forward in accordance with various conditions.

The present invention is not limited to the above embodiment, but may be directed to an automatic transmission having a gear train other than the gear train shown in FIG. The hydraulic circuit is not limited to the configuration shown in FIG.

[0033]

As described above, according to the hydraulic control apparatus of the present invention, the reverse gear is inhibited even if any of the range switching valves in the range switching mechanism malfunctions, and the plurality of forward gears and the neutral state are established. Therefore, according to the device of the present invention, stable limp-home running at the time of a failure becomes possible.

[Brief description of the drawings]

FIG. 1 is a partial hydraulic circuit diagram showing a part of a hydraulic circuit according to an embodiment of the present invention.

FIG. 2 is a partial hydraulic circuit diagram showing another portion of the hydraulic circuit in one embodiment of the present invention.

FIG. 3 is a schematic block diagram including a gear train showing one embodiment of the present invention.

FIG. 4 is a chart showing an operation table of each solenoid valve and each friction engagement device for setting each shift speed.

[Explanation of symbols]

 200 First range switching valve 300 Second range switching valve 400 Reverse speed control valve B3 Third brake

Claims (1)

(57) [Claims] 1. A hydraulic control for a shift-by-wire automatic transmission that controls a range switching mechanism that selectively outputs a hydraulic pressure for setting a plurality of forward gears and a hydraulic pressure for setting a reverse gear based on an electric signal. in the device, the range switching mechanism, a first range switch valve for selectively outputting the oil pressure from at least two output ports is controlled based on the electric signal, before this first range switching valve
Based on the serial outputs and an electric signal switching to set a plurality of ranges including a forward range to set the reverse range and the forward stage for setting the reverse stage the hydraulic pressure output at least two output ports or al -Stage control having a second range switching valve which is controlled to be switched by a switch, and selectively interrupting supply to a friction engagement device for setting a reverse stage output from the hydraulic pressure output from the second range switching valve A hydraulic control device for a shift-by-wire automatic transmission, comprising a valve.