JP3398019B2 - Hydraulic control device for 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 fail-safe technique of a hydraulic circuit for achieving engine braking.

[0002]

2. Description of the Related Art In a conventional automatic transmission, one of different friction engagement elements is released and the other friction engagement element is released in order to prevent a shift shock due to tie-up of both friction engagement elements at the time of gear shifting. There is a one in which a one-way clutch is incorporated in a gear train in order to cancel the torque supporting state of the friction engagement element on the side of the gear train as the shift progresses. In such a transmission, the torque applied to the reaction force element reverses when the engine is driven at the gear position where the reaction force element of the planetary gear is locked by the one-way clutch and the coast state is reached. Be free. Therefore, torque from the wheel side is not transmitted to the engine via the gear train, and the engine braking effect cannot be obtained as it is. Therefore, conventionally, a friction engagement element capable of supporting torque in both directions, such as a multi-disc brake, is provided in parallel with the one-way clutch, and the friction engagement element is engaged to achieve engine braking. As an example of such a gear train, JP-A-61-41
There is a technique disclosed in Japanese Patent Publication No. 063.

By the way, the engine braking effect is
This is useful when traveling on a downhill road or the like, but when traveling on a congested road or the like, the frequent on / off of the accelerator pedal gives a jerky feeling, so it should not occur for smooth traveling. Therefore, in the conventional normal automatic transmission, the friction engagement element in parallel with the one-way clutch is released at the speed reduction stage of the "D" (drive) range in which all forward speed stages can be achieved for normal traveling. In order to prevent the engine braking effect from occurring, it is possible to achieve a limited number of gears on the low speed side. At low speeds in the range position such as "2" (second) range or "L" (low) range, The frictional engagement element is engaged so that an engine braking effect is produced. The selection of the range position is performed by mechanically switching a manual valve provided in the hydraulic control device of the automatic transmission with a shift lever.

In recent years, there has been proposed an automatic transmission that can be operated like a manual transmission in which the driver can directly select the gear stage. As an example of such a technique, there is a technique disclosed in JP-A-5-60210. This technique employs a circuit configuration in which the frictional engagement element for achieving engine braking is engaged by controlling the solenoid valve while the manual valve of the hydraulic control device remains in the "D" range position.

[0005]

By the way, in the automatic transmission according to the latter proposal, when the shift solenoid valve fails due to a lack of a signal or the like while traveling at the second speed in a state where the engine brake can be achieved. , The shift valve operated by the signal pressure is switched to the first speed achievement state.
At the time of this switching, the brake for achieving the second speed and the brake for achieving the second speed engine brake are released, and the brake for achieving the first speed engine brake is engaged, so that the automatic transmission is set to the first speed. The engine brake can be achieved. In particular, if such a downshift occurs during coasting, unexpectedly strong engine braking will be applied, and the driver will feel a great deal of discomfort.

Therefore, in the present invention, even if a failure occurs in the shift solenoid valve in the engine brake achievable state, the resulting downshift is identified as a normal downshift and the automatic braking is avoided. A first object of the present invention is to provide a hydraulic control device for a transmission.

A second object of the present invention is to mechanically guarantee the operation of the hydraulic control device by the hydraulic circuit configuration only so that the engine braking effect will not occur at the time of downshifting due to the occurrence of the failure. And

A third object of the present invention is to minimize the increase in the number of parts for adopting the above circuit configuration.

A fourth object of the present invention is to most effectively exert the effect of reducing the uncomfortable feeling given to the driver.

[0010]

Means for Solving the Problems In order to achieve the above-mentioned first object, the present invention engages different frictional engagement elements at a predetermined shift speed and another shift speed to establish an engine braking state. An achievable automatic transmission, wherein a hydraulic control device that controls the friction engagement element includes a switching valve that controls supply and discharge of hydraulic pressure to and from the friction engagement element, and the hydraulic pressure supply and discharge to and from the switching valve. A first solenoid valve that outputs a signal pressure for controlling the above, and a second solenoid valve that outputs a different signal pressure between the predetermined shift stage and another shift stage. And an engine break at a predetermined shift stage in a state where the hydraulic pressure can be supplied by the switching valve.
Of the hydraulic pressure supply to the frictional engagement element to achieve the
An engine at a predetermined shift stage , which has a control valve for applying a signal pressure output from a second solenoid valve to the switching valve when shifting from another shift stage to a predetermined shift stage at the time of disconnection.
Hydraulic supply to the frictional engagement element that makes it possible to achieve the braking state.
When shifting from another gear to a predetermined gear when the supply is cut off , the signal pressure output from the second solenoid valve is
By being applied to the switching valve by the control valve,
By cutting off the supply of hydraulic pressure that due to the switching valve, the predetermined
It is characterized in that the achievement of the engine braking state by the engagement of the frictional engagement element that makes it possible to achieve the engine braking state at the shift speed is avoided.

Further, in order to achieve the above-mentioned second object, the control valve connects the second solenoid valve to the switching valve by a signal pressure applied by shifting to the predetermined gear. To be done.

Further, in order to achieve the third object, a shift valve that switches between the predetermined shift stage and another shift stage is arranged between the switching valve and the friction engagement element. It is composed.

In order to achieve the above-mentioned fourth object,
The predetermined shift speed is the first speed, and the other shift speeds are shift speeds on the higher speed side.

[0014]

According to the present invention, the second solenoid valve causes the switching valve to release the frictional engagement element for achieving the engine brake at the predetermined shift speed at the shift speed other than the predetermined shift speed. Since the signal pressure is output to switch to such a position, in the unlikely event that the stick of the shift valve or the fail of the shift solenoid valve fails, the engine can be braked to another gear by the predetermined gear while running. Even if the shift down occurs, the control valve is switched to apply the signal pressure from the second solenoid valve to the switching valve when the predetermined shift speed is reached, so that the switching valve is switched by the second solenoid valve. The supply of hydraulic pressure to the frictional engagement element for achieving engine braking at a predetermined shift speed is cut off . Therefore, according to the present invention, it is possible to reduce the uncomfortable feeling due to the downshift not intended by the driver when the engine brake is applied.

Further, in the structure according to the second aspect, the control valve is opened by the signal pressure applied by the shift to the predetermined shift stage, whereby the second solenoid valve is connected to the switching valve. Since the operation of discharging the hydraulic pressure is caused by the switching valve, the frictional engagement element for achieving the engine brake is released only by mechanical switching of the hydraulic circuit of the hydraulic control device, and the engine brake operates. It is possible to mechanically ensure the effect of reducing the discomfort caused by the driver's unexpected downshift.

Further, according to the third aspect of the invention, since the shift valve can switch the hydraulic pressure supply between the switching valve and the friction engagement element in accordance with the shift speed, the shift valve can change the speed. Since it is possible to control a plurality of different friction engagement elements for achieving engine braking according to the number of stages, it is possible to reduce the number of valves and realize cost reduction.

According to the fourth aspect of the present invention, it is possible to prevent the engine braking effect from occurring in the first speed state, which gives the greatest deceleration feeling, by downshifting at the time of failure. Therefore, even if a failure occurs, it is possible to reduce the discomfort felt by the driver.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. As shown by a skeleton gear train in FIG. 2, this transmission uses a torque converter T with a lock-up clutch as a starting device and combines two planetary gear units U1 and U2 as speed change elements to form three forward gears and one reverse gear. As an automatic transmission having a four-speed structure, an overdrive mechanism including a planetary gear unit U0 is arranged in the preceding stage as the transmission mechanism.

The planetary gear unit U0 be connected to the torque converter T is connected to the carrier C ₀ to the turbine output shaft, clutch the sun gear S _0, parallel C-
0 and the one-way clutch F-0 are connected to the carrier C ₀ , and the sun gear S ₀ can be locked by the brake B-0. The ring gear R _0, which constitutes the output element of the planetary gear unit U0, is connected to the transmission mechanism at the subsequent stage via the parallel clutches C-1 and C-2.

The ring gear R ₁ of the planetary gear unit U1 is connected to the clutch C- ₁ and the clutch C-2 is connected.
Are both sun gears S ₁ and S of both gear units U 1 and U 2.
_Two are connected. The carrier C ₁ of the planetary gear unit U1 is connected to the ring gear R ₂ of the planetary gear unit U2, and the carrier C ₁ and the ring gear R ₂ are connected to the output shaft as an output element of the automatic transmission. Further, both sun gears S ₁ and S ₂ can be locked by a brake B-1, and can also be locked by a one-way clutch F-1 and a brake B-2 which are connected in series, so that the carrier C of the planetary gear unit U2 can be locked.
₂ is a parallel one-way clutch F-2 and brake B
It can be locked by -3.

As shown in the engagement chart of FIG. 3, the automatic transmission having the above-mentioned structure is arranged so that each selected range position,
That is, "P" (parking), "R" (reverse),
Each clutch C-0 to C-2 and brake B-0 to B corresponding to "N" (neutral), "D", "2", "L"
-3 engagement or disengagement, one-way clutch (OW.
C) It operates by locking or freeing F-0 to F-2. In the figure, a circle indicates engagement for each clutch and brake, a lock for one-way clutch, and a cross indicates release for the same clutch and brake, and free for one-way clutch.

As can be seen by referring to FIGS. 2 and 3 as well, in the third speed of the automatic transmission, the clutch C-0 is engaged and the planetary gear unit U0 is directly connected, and the clutch C-1 and the clutch C-1 are connected. This is achieved when C-2 is engaged and both planetary gear units U1 and U2 are directly connected. Further, in the fourth speed, the carrier C takes a reaction force to the sun gear S ₀ locked by the engagement of the brake B-0.
This is achieved by increasing the rotation speed of the ring gear R ₀ by the rotation of the _0- supported pinion and by directly connecting the two planetary gear units U1, U2 with both the clutch C-1 and the clutch C-2 engaged. Overdrive status is entered.

The second speed in the "D" range manual (MANUAL) mode according to the subject matter of the present invention is different from the second speed in the "D" range auto (AUTO) mode. The engagement state of the brake B-1 similar to the second speed in the L "range is obtained to obtain the engine braking effect during coasting. At this time, in the engine driven state, the ring gear R
_With the input to ₁ , the one-way clutch F-1 is locked and the brake B-2 is engaged, and the revolution of the pinion due to the reaction force of the sun gear S ₁ is output as the rotation of the carrier C ₁ . On the other hand, during coasting, the input to the carrier C ₁ takes a reaction force due to the engagement of the brake B- ₁ to lock the sun gear S ₁ , and is output to the ring gear R ₁ in the reverse path.

Further, the "D" range manual (MAN
In the first speed in the (UAL) mode, when the engine is driven, the input to the ring gear R ₁ locks the carrier C ₂ by locking the one-way clutch F-2, and the reaction force rotation due to the reverse rotation of the sun gear S ₁ causes the ring gear R _{1 to} rotate. It is output as a normal rotation of ₂ . On the other hand, during coasting, the input to the ring gear R ₂ is the engagement of the brake B-3 to lock the carrier C ₂ , and the reaction force rotation due to the reverse rotation of the sun gear S ₁ is output as the forward rotation of the ring gear R _1. To be done.

Next, the structure of the engine brake control circuit portion of the hydraulic control device for controlling the clutch and brake of the gear train will be described with reference to FIG. This circuit
The line pressure (P _L ), which is obtained by adjusting the discharge pressure of the pump (not shown) by the primary regulator valve according to the vehicle running load, is supplied to the “D” range pressure (P _D) according to the switching position by operating the shift lever. ), "2" range pressure,
A manual valve 1 for outputting the “L” range pressure (P _L ) and the “R” range pressure (P _R ) to each oil passage is provided. The figure shows the neutral state of the manual valve 1.

The engine brake is applied to the oil passages L1 and L2 to which the "D" range pressure (P _D ) and the "L" range pressure (P _L ) are supplied from the manual valve 1 at the first speed and the second speed. To achieve this, a coast brake relay valve 2 is inserted as a switching valve. This relay valve 2
A frictional engagement element for achieving selective engine braking of either "D" range pressure (P _D ) or "L" range pressure (P _L ), that is, the brake B-3 in this embodiment.
And a control of the supply to the brake B-1, more specifically, a switching valve having a function of supplying to one side and shutting off and discharging the other. Therefore, the coast brake relay valve 2
Has lands 21 and 22 at both ends and is slidable in the valve hole, a return spring 23 that exerts a spring return force on one end of the spool 20, and a displacement force caused by a signal pressure on the other end. Therefore, the plunger 24 is slidable in the valve hole.

The oil passage L3, which is supplied with the oil pressure through the coast brake relay valve 2, is branched into two, and the signal pressure output by the shift solenoid valve S1 shown by the symbol in the drawing (hereinafter, in each of the embodiments, The hydraulic pressure generated in the oil passage due to the closing of the solenoid valve is switched between the second speed and the third speed in accordance with (Solenoid pressure) (P _{S 1} ) to connect the circuit to the oil passage capable of achieving each shift speed. The 2-3 shift valve 3 which makes it a state is connected.

2-3 One output oil passage L4 of the shift valve 3
Is an oil passage that can achieve the respective shift speeds by switching between the first speed and the second speed according to the solenoid pressure (P _{S 2} ) output by the shift solenoid valve S2, which is also indicated by the symbol. It is connected to the 1-2 shift valve 4 which is brought into the connected state. Output oil passage L5 of 1-2 shift valve 4 corresponding thereto
Is connected to a brake B-3 as a friction engagement element for achieving the first speed engine brake. The valve inserted in the oil passage L4 that connects the 2-3 shift valve 3 and the 1-2 shift valve 4 is the low coast modulator valve 5. The modulator valve 5 reduces the "D" range pressure (P _D ) supplied via the 2-3 shift valve 3 in accordance with the required engagement torque of the brake B-3 when the engine brake of the first speed is achieved. It is for supplying to the 1-2 shift valve 4.

2-3 The other output oil passage L6 of the shift valve 3
Is directly connected to the 1-2 shift valve 4, and the corresponding output oil passage L7 of the 1-2 shift valve 4 passes through the second coast modulator valve 6 and is a brake as a friction engagement element for achieving the second speed engine brake. It is connected to B-1. The second coast modulator valve 6 is also in the "D" range supplied via the 2-3 shift valve 3 and the 1-2 shift valve 4 in accordance with the required engagement torque of the brake B-1 when the second speed engine brake is achieved. It is for reducing the pressure (P _D ).

The second coast modulator valve 6
The valve 7 inserted in the oil passage L7 that connects the brake B-1 for achieving the second speed engine brake is a cut-off valve. The cutoff valve 7 is switched between the manual mode and the automatic speed change mode to change the hydraulic pressure supply speed to the brake B-1 as the friction engagement element for achieving the second speed engine brake. Functions to improve the brake engagement response.

Further, the hydraulic pressure (P _L ) of the line pressure oil passage is supplied to the outer end of the plunger 24 of the coast brake relay valve 2 through the orifice, and the signal pressure oil passage LS3 is supplied with a solenoid. A signal is released when it is turned on or applied when it is turned off (in this specification, output including both release and application of signal pressure; therefore, output of signal pressure does not necessarily mean supply of pressure). The on-off solenoid valve S3 is attached as the first solenoid valve according to the present invention. The signal pressure oil passage LS3 is also connected to the spool end of the cutoff valve 7 so that the signal pressure can be applied.

In accordance with the features of the present invention, the coast brake relay valve 2 is provided with a separate plunger 24 that comes into contact with the end of the spool 20 thereof, and has a second pressure receiving portion at the end of the spool 20. Therefore, the spool 20 applies the solenoid pressure (P _{S 3} ) to the outer end of the plunger 24 and the solenoid pressure (P _{S 3} ) to the end of the spool 20 which will be described in detail later.
"D" range pressure oil passage L by any application of _{S 4} )
It is possible to cut off 1 and connect the drains of the oil passages L3 to L7 downstream thereof.

The hydraulic pressure (P _L ) of the line pressure oil passage is supplied to the signal pressure oil passage LS4 for applying the solenoid pressure (P _{S 4} ) to the second pressure receiving portion through the orifice, and the hydraulic pressure is applied to the solenoid signal. A normally-closed on / off solenoid valve S4 that is released when turned on or applied when turned off is attached. A coast brake control valve 8 is inserted in the oil passage LS4. The coast brake control valve 8 is
The spool return valve is a spring-return type spool valve that opens and closes when a signal pressure is applied to its spool end. In this embodiment, the signal pressure for detecting the first speed is the friction engagement engaged to achieve the gear position. Supply pressure to brake B-2 (P _{B 2} )
It is said that. It should be noted that this signal pressure (P _{B 2} ) is always supplied at the second speed or higher, as can be seen with reference to FIG. 3, and therefore the coast brake control valve 8
Is always kept in the shut-off state except when the first speed is achieved.

FIG. 4 shows the first of the solenoid valves shown in FIG.
The solenoid signal pattern is shown by excerpting the operation diagrams at the second speed and the second speed. As shown in the figure, the shift solenoid valve S1 is always on (released in this embodiment) in both the first speed (1st) and the second speed (2nd). Further, the shift solenoid valve S2 is turned on at the second speed (also released).
It is said that The solenoid valve S3 is turned on (also released) only when the engine brake (E / G) is achieved, whereas the solenoid valve S4 is turned on (also released) only when the engine brake of the first speed is achieved. Has been done. Therefore, in the second speed, the solenoid valve S2 is turned off due to a missing signal or the like, and the signal pattern when the engine brake is achieved in the normal first speed is the solenoid valve S4.
The signals can be identified by turning them on and off.

The hydraulic circuit having such a structure operates as follows. First, at the first speed in the AUTO mode, the solenoid pressure (P _{S 1} ) that has been applied to the spool end of the 2-3 shift valve 3 is turned on by the normally closed shift solenoid valve S1 being turned on. Since it is released, the spool switches to the position shown in the right half of the figure. Further, since the solenoid valve S3 is turned off, the coast brake relay valve 2 is applied with the solenoid pressure (P _{S 3} ) at the outer end of the plunger 24 thereof, and the land 22 of the spool 20 causes the manual valve 1 to operate. Oil path L1 from
Is closed, and the oil passages L3 to L5 downstream thereof are drain-connected via the oil passage L2 and the manual valve 1. As a result, the brake B-3 for achieving the first speed engine brake is obtained.
The hydraulic pressure of is discharged and engine braking is not achieved.

On the other hand, a manual (MANUA
L) mode 1st speed, shift solenoid valve S
1 and both solenoid valves S3 and S4 are turned on. As a result, the coast brake relay valve 2 releases the application of the solenoid pressure (P _S3 ) to the end of the plunger 24,
The spool 20 is at the right half position in the figure. Also, 2-3
The shift valve 3 is in the spool position shown in the right half of the figure for the above reason. Further, the 1-2 shift valve 4 is in the spool position shown in the right half of the figure because the solenoid pressure (P _{S 2} ) is being applied. Therefore, in this case, the "D" range pressure (P _D ) supplied from the manual valve 1 is supplied to the low coast modulator valve 5 via the coast brake relay valve 2 and the 2-3 shift valve 3 and is reduced in pressure there. The modulator pressure is supplied to the brake B-3 via the 1-2 shift valve 4. This state is shown by marking the oil passages with ● and ○ marks.

Next, in the second speed in the AUTO mode, both shift solenoid valves S1 and S2 are operated.
Is turned on and the solenoid valve S3 is turned off. At this time, the coast brake relay valve 2 is applied with the solenoid pressure (P _{S 3} ) to the outer end of the plunger 24 thereof, as in the case of the first speed in the automatic mode. Supply oil passage L1
Is cut off, and the oil passages L3, L5, L6 downstream thereof are drain-connected via the oil passage L2 and the manual valve 1.
As a result, the hydraulic pressure of the brake B-1 for achieving the second speed engine brake is discharged, and the engine brake is not achieved.

Further, the second speed in the manual mode is achieved by turning on both shift solenoid valves S1 and S2 and solenoid valve S3. In this case, the coast brake relay valve 2 is released from the application of the solenoid pressure (P _{S 3} ) to the end of the plunger 24, and becomes the spool position in the right half of the drawing. Further, the 2-3 shift valve 3 is in the spool position shown in the right half of the figure for the above reason. Furthermore,
The 1-2 shift valve 4 is also in the spool position shown in the left half of the figure because the solenoid pressure (P _{S 2} ) is released.
Therefore, in this case, the "D" range pressure (P _D ) supplied from the manual valve 1 is supplied to the low coast modulator valve 5 via the coast brake relay valve 2 and the 2-3 shift valve 3 and is reduced in pressure there. The modulator pressure (P _DM ) is supplied to the 1-2 shift valve 4, but is shut off by the shift valve 4 and is not supplied to the brake B-3. On the other hand, coast brake relay valves 2 to 2-
The “D” range pressure (P _D ) supplied to the second coast modulator valve 6 via the 3 shift valve 3 and the 1-2 shift valve 4 is reduced by the modulator valve 6 and reaches the cutoff valve 7, where After that, it is supplied to the brake B-1. Therefore, in this case, engine braking is achieved by the engagement of the brake B-1.

In the third speed in this embodiment,
Although there is a difference between on and off of the solenoid valve S3 in the auto mode and the manual mode, in this case, regardless of whether the coast brake relay valve 2 has an output or not, the 2-3 shift valve 3 causes the hydraulic pressure to the engine brake related oil passage. Supply is not made. In this case, the gear train is directly connected.

Next, at the other shift speed according to the subject of the present invention, that is, when the second speed is achieved, the solenoid valve S for shifting is used.
In the unlikely event that 2 fails in the off state due to a missing signal or the like, the 1-2 shift valve 4 is switched to the 1st speed (right half) position by the application of the solenoid pressure (P _{S 2} ). The gear train is downshifted to achieve the first speed. At this time, if no special measures are taken, the circuit is in the state where the first mode engine braking in the manual mode can be achieved, and a stronger engine braking state than expected by the driver during coasting occurs.

On the other hand, in this embodiment to which the present invention is applied, the second solenoid valve S4 is turned off so that the first speed engine brake is not applied. That is, in this case, the brake B being supplied to the coast brake control valve 8 at the second speed or higher.
The -2 pressure (P _{B 2} ) is released by the shift to the first speed, which opens the coast brake control valve 8. As a result, the solenoid pressure (P _{S 4} ) is applied to the coast brake relay valve 2 via the coast brake control valve 8, and the spool 20 is pushed down to cut off the “D” range pressure oil passage L1. The oil passages L3 to L5 downstream thereof are drain-connected via the oil passage L2 and the manual valve 1. As a result, despite the first speed state in the manual mode, the oil pressure in the oil passage indicated by the circle in the figure is discharged, and the engine brake avoidance state can be obtained.

Thus, according to this embodiment, "D"
Addition of control valve and solenoid valve to various failures such as lack of solenoid signal, failure of solenoid valve, shift valve stick, etc. in hydraulic control circuit that can achieve first and second speed engine braking in range By doing so, it is possible to avoid the discomfort when the downshift to the first speed occurs due to the failure by canceling the engine braking achievement state.

The present invention has been described above based on the embodiment. However, the present invention can be modified by changing the concrete constitution of various details within the scope of matters described in each claim of the present invention. It can be carried out.

[Brief description of drawings]

FIG. 1 is a partial circuit diagram of a hydraulic control device of an embodiment to which the present invention is applied.

FIG. 2 is a skeleton diagram showing a gear train of the automatic transmission according to the above embodiment.

FIG. 3 is an operation chart of the automatic transmission according to the above embodiment.

FIG. 4 is a chart showing a solenoid signal pattern by extracting the operation chart.

[Explanation of symbols]

B-1 Brake (friction engagement element) B-3 Brake (friction engagement element) S3 Solenoid valve (first solenoid valve) S4 solenoid valve (second solenoid valve) 2 Coast brake relay valve (switching valve) 3 2-3 shift valve 4 1-2 shift valve (shift valve) 8 Coast brake control valve (control valve)

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuto Yamada 10 Takane, Fujii-cho, Anjo City, Aichi Prefecture Aisin AW Co., Ltd. (72) Inventor Jiji 23 Takane Fujii-cho, Anjo City, Aichi Prefecture No. 10 Aisin AW Co., Ltd. (72) Inventor Hiroyuki Tsukamoto Takane Fujii-cho, Anjo City, Aichi Prefecture No. 10 Aisin AW Co., Ltd. (72) Inventor Kazunori Ishikawa Takane Fujii-cho, Anjo City, Aichi Prefecture No. 10 Aisin AW Co., Ltd. (72) Inventor Kunihiro Iwatsuki 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Toru Matsubara 1 Toyota Town, Aichi Prefecture Toyota City In-vehicle Co., Ltd. (72) Inventor Kagenori Fukumura 1 Toyota-cho, Toyota-shi, Aichi Toyota Automobile Co., Ltd. (72) Inventor Hiji Shinji 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Koji Taniguchi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (56) Reference JP 62-17452 (JP) , A) JP-A-1-288654 (JP, A) JP-A-3-14964 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (4)

(57) [Claims] 1. An automatic transmission capable of attaining an engine braking state by engaging different friction engagement elements at a predetermined shift speed and another shift speed, and a hydraulic pressure for controlling the friction engagement element. The control device includes a switching valve that controls supply and discharge of hydraulic pressure to and from the friction engagement element, and a first solenoid valve that outputs a signal pressure for controlling the hydraulic supply and discharge to the switching valve. In a hydraulic control device for an automatic transmission, a second solenoid valve that outputs a different signal pressure between the predetermined shift speed and another shift speed, and a predetermined shift speed in a hydraulic pressure supply enabled state by the switching valve
Friction engagement element that can achieve the engine braking state of the vehicle
During the shift from the other speed stage to a predetermined gear stage at the time of interruption of the supply of hydraulic pressure to, and a control valve for applying a signal pressure output from the second solenoid valve to the switching valve, a predetermined gear stage The engine braking condition at
Other shifts when the hydraulic pressure supply to the friction engagement element is interrupted
When shifting from a gear to a predetermined gear, the second solenoid
The signal pressure output from the valve is changed by the control valve to the switching valve.
By being applied to the hydraulic supply of the that by the switching valve
To shut off the engine brake at the specified gear.
A hydraulic control device for an automatic transmission, characterized in that the achievement of an engine braking state by the engagement of a frictional engagement element capable of achieving the state is avoided. 2. The hydraulic control of an automatic transmission according to claim 1, wherein the control valve connects the second solenoid valve to a switching valve by a signal pressure applied by shifting to the predetermined gear stage. apparatus. 3. Between the switching valve and the friction engagement element,
3. The hydraulic control device for an automatic transmission according to claim 1, wherein a shift valve that switches between the predetermined shift speed and another shift speed is arranged. 4. The hydraulic control of the automatic transmission according to claim 1, wherein the predetermined gear is the first gear and the other gears are gears on the higher gear side. apparatus.