JP2909942B2 - Hydraulic control device for automatic transmission for vehicles - 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 system for an automatic transmission for a vehicle, and more particularly to a hydraulic control system for a vehicle when a predetermined condition is satisfied even when a shift range is set to a forward drive range. Automatic transmission for vehicles that releases clutches (clutches that are engaged to achieve forward running) via control valves (including substantial release by reducing oil pressure) and forms a neutral state to prevent creep from occurring The present invention relates to a hydraulic control device for a machine.

[0002]

2. Description of the Related Art Conventionally, in an automatic transmission for a vehicle, if a shift range is set to a driving range such as a drive range, even if the vehicle speed is substantially zero, the gear of the automatic transmission will The transmission is set to the first speed (or the second speed) without being in the neutral state. Therefore, the output of the internal combustion engine is always transmitted to the forward clutch of the gear transmission via the torque converter, so that so-called creep occurs. As a result, in order to keep the vehicle stopped, the brake pedal must be depressed. I needed to.

[0003] Further, the drag of the torque converter at this time deteriorates the fuel consumption efficiency, and further causes a problem that the temperature of the hydraulic oil of the torque converter rises.

In view of the above, a control valve for controlling the hydraulic pressure of the forward clutch is newly provided. When the accelerator pedal is released and the vehicle is substantially stopped, the shift range is set to the drive range. Even when the vehicle is in the forward travel range, the forward clutch is released or depressurized through the control valve, automatically forming a neutral state to prevent the occurrence of creep and improve fuel consumption efficiency. In addition, there is known a technique for suppressing a rise in the temperature of hydraulic oil in a torque converter (for example, Japanese Patent Application Laid-Open No.
106449).

[0005] Normally, when such transition control to the neutral state (hereinafter referred to as creep reduction control) is performed, the vehicle can be prevented from retreating on a slope or the like in order to prevent the vehicle from retreating. In the hydraulic control unit)
The so-called hill hold control for engaging the brake is also performed.

In order to better understand the present invention,
A specific example of an automatic transmission configured to perform such creep reduction control and hill hold control will be described in some detail.

FIG. 4 shows an overall outline of an automatic transmission for a vehicle. This automatic transmission includes a torque converter section 20, an overdrive mechanism section 40, and an underdrive mechanism section 60 having three forward stages and one reverse stage.

The torque converter section 20 includes a pump 2
1, a turbine 22, a stator 23, and a lock-up clutch 24.
Is transmitted to the overdrive mechanism 40.

The overdrive mechanism 40 includes a sun gear 43, a ring gear 44, a planetary pinion 42,
And a set of planetary gear units consisting of
The rotational state of the planetary gear unit is controlled by a clutch C0, a brake B0, and a one-way clutch F0.

The underdrive mechanism 60 includes two sets of planetary gear units including a common sun gear 61, ring gears 62 and 63, planetary pinions 64 and 65, and carriers 66 and 67. The rotation state and the connection state with the overdrive mechanism 40 are controlled by clutches C1, C2, brakes B1 to B3, and one-way clutches F1, F2.

The automatic transmission includes the above-described transmission unit and a computer 84. The computer 84 has a throttle sensor 80 for detecting a throttle opening θ for reflecting the load of the engine 1 and a vehicle speed N.
Signals for various controls such as a vehicle speed sensor (rotation speed sensor of the output shaft 70) 82 for detecting 0 and a C0 rotation speed sensor 99 for detecting the rotation speed of the clutch C0 are input.

The computer 84 controls the hydraulic control circuit 8 in accordance with a preset throttle opening-vehicle speed shift point map.
The solenoid valve in 6 is driven and controlled, and a shift is executed by performing a combination of engagement of each clutch and brake as shown in FIG.

Here, the clutch C1 corresponds to a forward clutch released during creep reduction control, and the brake B1 corresponds to a brake engaged during hill hold control.

When the shift range is in the forward running range, the forward clutch C1 is normally in the engaged state,
The vehicle is ready for forward running. However, even if the shift range is the forward running range, the throttle opening θ
Is zero (or the idle contact is ON) and the vehicle speed is zero (including substantially zero), the engagement pressure of the clutch C1 is reduced to shift the automatic transmission to a neutral state. At the same time as (creep reduction control), the brake B1 is engaged to activate the hill hold function (hill hold control).

Next, an example of a hydraulic control device for executing creep reduction control and hill hold control will be described with reference to FIGS. 6 and 7. FIG.

In the drawing, reference numeral 110 denotes a manual shift valve. This manual shift valve 1
10 has a hydraulic input port 114. The hydraulic pressure input port 114 is supplied with a line pressure PL sucked up by an oil pump 120 and regulated by a primary regulator valve 124 via an oil passage 126.

The manual shift valve 110 has a spool 112 driven by a manual shift lever (not shown), and connects a hydraulic input port 114 to a D range port 116 when the manual shift range is the D range. When the manual shift range is the S range (two ranges), the hydraulic input port 114
To the S range port 118.

D range port 116 is connected to oil passages 300, 30.
The S range port 118 is connected to the port 146 of the 2-3 shift valve 140 through the oil passage 304.
−3 is connected to the port 148 of the shift valve 140.

The 2-3 shift valve 140 is provided on the spool 1
42. When no hydraulic pressure is supplied to the port 144, the spool 142 is in the raised position shown in the right half of the drawing, and connects the port 146 to the port 150,
In addition, the port 148 communicates with the port 152.

On the other hand, when the hydraulic pressure is supplied to the port 144, the port 144 is at the lower position shown in the left half of the figure, and the communication between the port 146 and the port 150 is cut off. Cut off,
The port 152 communicates with the drain port 154.

The supply of hydraulic pressure to the port 144 is performed by a solenoid valve (not shown) in a known manner, and the hydraulic pressure is supplied to the port 144 only when the third speed or the overdrive speed (fourth speed) is achieved. It has become so. Therefore, the spool 142 is at the raised position when the first speed or the second speed is achieved, and is at the lowered position when the third speed or the overdrive speed is achieved.

The port 150 is connected to a port 186 of the B1 control valve 180 by an oil passage 306. The port 152 is connected to the port 172 of the check valve 170 via the oil passage 308, the second coast modulator valve 160, and the oil passage 310.

The check valve 170 is connected to the inlet port 17.
In addition to the inlet port 174 and the outlet port 174, when an oil pressure is supplied to the inlet port 172 by the action of the check ball 178, the inlet port 174 is closed. When the hydraulic pressure is supplied to the inlet port 172, the inlet port 172 is closed.

The inlet port 174 is connected to the
1 The outlet port 176 is connected to the port 188 of the control valve 180, and the outlet port 176 is connected to the port 136 of the 1-2 shift valve 130 by an oil passage 314.

The 1-2 shift valve 130 has a spool 13
2 When hydraulic pressure is not supplied to the port 134, the spool 132 is in the raised position shown in the left half of the figure and communicates the ports 136 and 138. On the other hand, when hydraulic pressure is supplied to the port 134, the right half of the figure is The port 136 is disconnected from the drain port 139 by shutting off the ports 136 and 138 at the lower position shown in FIG.

A hydraulic pressure is supplied to the port 134 only when the first speed is achieved by the action of a solenoid valve (not shown).
Thus, the spool 132 is set to the raised position when the second speed, the third speed, or the overdrive speed is achieved, and is set to the lowered position only when the first speed is achieved.

The port 138 is connected to the brake B1 by an oil passage 316.

The B1 control valve 180 has a spool 182 and a plug 184. When the spool 182 is in the raised position shown in the right half of FIG.
86 and 188 and ports 190 and 192
And the port 192 is communicated with the drain port 198.

On the other hand, when in the lowered position shown in the left half of the figure, the port 186 is closed and the port 18 is closed.
8 to the drain port 187 and the port 190
And 192 are communicated.

Port 190 is connected to oil passage 314 and oil passage 300
Is connected to the D range port 116 of the manual shift valve 110, and the port 192 is connected to the port 208 of the C1 control valve 200 by an oil passage 316.

The spool 182 has ports 194 and 196
Driven by hydraulic pressure applied to ports 194 and 1
96, a signal oil pressure P equal to or more than a predetermined value Psset.
When s is supplied, it is located at the left half position, that is, the hill hold control release position. Also, port 194
And 196, the signal oil pressure Ps equal to or more than the predetermined value Psset
Is not supplied, the position is at the right half position, that is, the hill hold control position.

The port 194 is connected to the oil passage 3 by the oil passage 318.
20 and is supplied with the signal oil pressure Ps of the oil passage 320. The port 196 is supplied with throttle oil pressure or servo oil pressure (engagement pressure) for the clutch C1 through an oil passage (not shown).

The solenoid valve 240 operates according to the duty ratio D of the pulse signal applied to the electromagnetic coil.
A signal pressure Ps corresponding to the duty ratio D is generated in the oil passage 320. The solenoid valve 240 is constituted by a so-called normally-closed solenoid valve.
Decreases as the duty ratio D applied to the electromagnetic coil increases.

The oil passage 320 passes through the throttle 280, the oil passage 322, the modulator valve 250, and the oil passage 324, and
, Whereby the oil pressure 322 regulated to a predetermined constant pressure by the modulator valve 250 is supplied to the oil passage 322.

The oil passage 320 is connected to the oil passage 318 by B1.
It is connected to the port 194 of the control valve 180 and is also connected to the port 210 of the C1 control valve 200 via the oil passage 326 and the throttle 282.

The C1 control valve 200 has a spool 202 and two plugs 204 and 206.
Spool 202 is connected to oil passage 3 by oil passages 328 and 314.
00 and a port 21 to which the line pressure PL is supplied.
By controlling the degree of communication with the second drain port 216, the hydraulic pressure at the outlet port 214 is adjusted.

The pressure adjustment value increases in accordance with the urging force applied to the spool 202 by the compression coil spring 218 and the pressing force applied directly to the spool 202 by the plugs 204 and 206. Exit port 21
Reference numeral 4 is connected to the clutch C1 via the throttle 284 and the oil passage 330.

The oil passages 328 and 330 are connected to the oil passage 31
4. Connected by a check valve 260. The check valve 260 is configured to allow only the flow of the oil from the oil passage 330 to the oil passage 328, that is, the drain flow of the oil.

Next, the operation will be described.

When the manual shift range is set to the D range and the first speed is established, the spool 132 of the 1-2 shift valve 130 is at the lowered position,
The spool 142 of the 2-3 shift valve 140 is in the raised position.

The creep reduction control and the hill hold control have not been started yet, and the solenoid valve 240 is turned off.
While the F signal is given, the signal oil pressure P
s is set to the same oil pressure as the output oil pressure Pm of the modulator valve 250, and this oil pressure is set to the B1 control valve 18
0 port 194 and port 210 of the C1 control valve 200.

Accordingly, at this time, the spool 180 of the B1 control valve 180 is located at the left position, that is, the hill hold control start position, whereby the port 186 is closed and the port 188 is connected to the drain port 187.

When the port 190 communicates with the port 192, the line pressure PL from the oil passages 300 and 314 is increased.
Enters the port 208 of the C1 control valve 200 through the oil passage 316, and the C1 control valve 2
00 is located at the left position, that is, the normal mode position, by the action of the line pressure PL supplied to the port 208 in addition to the signal oil pressure Ps applied to the port 210.

As a result, the line pressure PL applied to the port 212 due to the complete closing of the drain port 216 is introduced into the clutch C1 from the port 214 via the oil passage 330 without being reduced.

Therefore, at this time, the clutch C1 is completely engaged, and the first speed is achieved. Further, since the port 186 of the B1 control valve 180 is closed, the port 188 is drain-connected, and the port 136 of the 1-2 shift valve 130 is also closed, and the port 138 is drain-connected. Is not supplied, and the brake B1 maintains the released state.

When the manual shift range is set to the D range, the throttle opening of the engine 1 is returned to the idle opening position (idle contact O
N) When the vehicle speed falls below a predetermined value close to zero, a predetermined signal is given to the solenoid valve 240 in order to perform creep reduction control and hill hold control, and the duty ratio D increases with time. Done.

As the duty ratio D increases, the oil passage 3
The signal pressure Ps at 20 gradually decreases over time,
When the signal oil pressure Ps decreases to a predetermined value Psset, B
1 The spool 182 of the control valve 180 switches to the right position in the figure, and the communication port of the port 188 switches from the drain port 187 to the port 186. Also, the communication port of the port 192 is changed from the port 190 to the drain port 1.
Switch to 98.

Accordingly, since the line pressure PL is not supplied to the port 208, the pressure adjustment value of the C1 control valve 200, that is, the engagement pressure of the clutch C1 is set by the signal oil pressure Ps applied to the port 210, and the signal oil pressure Ps The drain port 216 is opened with the decrease.

As a result, the clutch C1
The clutch C1 is caused to slip. Thus, the automatic transmission is in the same state as in the neutral state, and the occurrence of creep is prevented at the same time as the idle vibration is reduced. That is, creep reduction control is executed.

On the other hand, at this time, since the ports 186 and 188 of the B1 control valve 180 are in communication with each other as described above, the spool 142 of the 2-3 shift valve 140 is in the raised position, that is, the first gear or the second gear. In the switching position to achieve the step, the manual shift valve 11
If the line pressure PL of the D range port 116 of 0 is
0, 302, port 146 of 2-3 shift valve 140
And 150, oil passage 306, B1 control valve 18
0 through ports 186 and 188, an oil passage 312, a check valve 170, and an oil passage 314.
It reaches port 136 at 0.

Therefore, at this time, the 1-2 shift valve 1
30 if the spool 132 is in the raised position,
Line, the line pressure PL at port 136 is at port 1
The brake gear 38 is supplied to the brake B1 through the oil passage 316 so that the brake B1 is engaged and the sun gear is fixed.
Therefore, the rotation of each of the front sun gear and the rear sun gear is prevented, and the output shaft is prevented from rotating in the backward direction of the vehicle by the action of the one-way clutch F2, so that a so-called hill hold control is executed.

[0052]

By the way, when the above-mentioned control is to be performed by the above-mentioned device, if the spool 202 of the C1 control valve 200 sticks in a reduced pressure state due to a defect such as a foreign matter or a processing defect, the control is thereafter performed. Even if a signal (duty ratio = 0) is given from the computer to the solenoid valve 240 so that the vehicle travels forward in the normal mode, the engagement pressure of the clutch C1 becomes only the oil pressure values of a to b or b to c in FIG. A problem arises in that the transmission capacity of the clutch C1 is insufficient and the vehicle cannot travel forward.

If the driver depresses the accelerator pedal strongly in this state, the engine speed and the input member of the clutch C1 (the ring gear 4
The rotation speed of 4) increases, and the clutch C1 keeps slipping, which may cause damage to the friction material of the clutch C1.

Similarly, the B1 control valve 18
If 0 is stuck in the hill hold control position (the right position in the figure), the D range line pressure PL for depressing the pressure reducing function of the C1 control valve 200 is not guided to the port 208, so the hydraulic pressure of the clutch C1 Figure 8
Pc1 ', and as a result, the clutch transmission torque capacity becomes insufficient, causing the same problem as described above.

Therefore, in order to prevent these problems,
The present applicant is concerned with a vehicle for which forward traveling can be ensured even if a failure occurs in a control valve for a forward clutch for performing creep reduction control or a control valve for a brake for performing hill hold control. Developed a hydraulic control device for an automatic transmission and filed an application as Japanese Patent Application No. 2-264644 (October 2, 1990).
Date application = unpublished).

Hereinafter, the contents of the hydraulic control device previously filed will be described with reference to FIG.

In this apparatus, the drain port 216 of the C1 control valve 200 and the drain tank 279
A C1 drain control valve 270 is arranged in the middle of an oil passage 338 that communicates with the valve. Then, the drain port 216 of the C1 control valve 200 and the port 276 of the C1 drain control valve 270 are connected to the oil passage 3
38.

The C1 drain control valve 270
Port 272 and the drain tank 279 are connected by an oil passage 340. Further, the D range line pressure PL generated at the D range port 116 of the manual valve 110 is led to the port 274 of the C1 drain control valve 270 by the oil passage 336.

This C1 drain control valve 270
The hydraulic pressure Ps (the hydraulic pressure for controlling the engagement of the clutch C1) from the linear solenoid valve 240 is applied via the oil passage 332 as the hydraulic pressure for controlling the pressure. Instead of the hydraulic pressure Ps of the linear solenoid valve 240, the hydraulic pressure from the port 192 of the B1 control valve 180 (the engagement pressure to be directed to the clutch C1) is applied to the oil passage 334.
The same effect can be obtained by acting in the same direction via (shown by a dotted line).

The port 274 and the port 276 are designed to communicate with each other in the state of the normal traveling mode (that is, the Ps pressure is large in the above-described configuration) by the action of the hydraulic pressure Ps. In addition,
As the switching Ps pressure, the Ps pressure in FIGS.
Set the oil pressure higher than the sset pressure.

Since the prior art is configured as described above, even if one or both of the B1 control valve 180 and the C1 control valve 200 fail, the linear solenoid valve 240
As long as the output pressure Ps of the C1 rises above a predetermined value, the line pressure PL from the D range port 116 of the manual valve 110 is connected to the port 276 of the C1 drain control valve 270.
, The pressure-reducing function of the C1 control valve 200 is depressed and the engagement pressure of the clutch C1 is not reduced, so that the vehicle can travel forward.

Further, the newly added C1 drain control valve 270 itself is connected to the ports 272 and 276, for example.
When the stick sticks in the communication state, the C1 control valve 200 (and the B1 control valve 1
As long as 80) operates normally, the D range line pressure is guided to the oil passage 330, so that the vehicle can travel forward without any trouble.

The C1 drain control valve 270
When the ports 276 and 274 are stuck in communication with each other, the creep reduction control by the C1 control valve 200 becomes impossible, but forward running is possible.

That is, according to this device, the fail-safe function for securing the forward running is improved in each step as compared with the prior art.

The C1 drain control valve 27
As the control pressure of 0, a throttle pressure can also be added. Thus, the higher the throttle pressure Pth, the faster the C1 drain control valve 270 can be switched, and the more quickly the pressure reducing function of the C1 control valve can be depressed. Even in the event that the solenoid valve 240 fails, forward travel can be performed by depressing the accelerator pedal (increase in throttle pressure).

The previously developed technology has the above-described structure and function, but as a result of subsequent studies, it has been found that the following problems may newly occur.

(1) In the hydraulic control device shown in FIG.
As the switching control signal pressure of the C1 drain control valve 270, the control pressure Ps (oil pressure from the oil passage 332) controlled by the linear solenoid valve 240 or the line pressure PL of the D range via the B1 control valve 180
(Oil pressure from the oil passage 334). Also in this case, the switching of the B1 control valve 180 is performed by the pressure Ps.

Therefore, when the pressure Ps decreases due to the foreign matter stick of the solenoid valve 240 or the pressure Ps decreases due to the pressure decrease of the modulator valve 250, the C1 drain control valve 270
Cannot be switched. That is, in the case of, the direct pressure P
When s decreases, switching becomes impossible.
Since the switching of the B1 control valve 180 is incomplete due to the decrease in the pressure Ps, the D range line pressure PL via the B1 control valve 180 becomes low, so that the switching of the C1 drain control valve 270 becomes impossible. This makes forward traveling impossible.

(2) When a hydraulic pressure (eg, throttle pressure) corresponding to the driver's accelerator operation is used as the switching control signal for the C1 drain control valve 270, when all the elements are functioning normally, the foot brake When OFF, the engagement hydraulic pressure of clutch C1 gradually increases,
Although creep running is possible without shock, when the C1 control valve 200 fails, the C1 drain control valve 2 is turned on in response to the increase in throttle pressure.
70 is switched, the line pressure PL is supplied to the clutch C1, and the vehicle can run forward.

However, since the throttle pressure tends to increase only when the accelerator is considerably opened,
When the C1 control valve 200 fails and creep running becomes impossible, the driver may feel the abnormality and open the accelerator to operate.

As a result, the C1 drain control valve 270 is suddenly switched by the increased throttle pressure,
The clutch C1 is suddenly engaged by the line pressure PL, and a strong acceleration shock may occur.

The present invention has been made in view of such a problem, and it is possible to secure forward traveling even when a modulator valve or a linear solenoid valve fails, and furthermore, a forward operation by an accelerator opening operation by a driver. It is an object of the present invention to solve the above-mentioned problem by providing a hydraulic control device for an automatic transmission for a vehicle that can avoid sudden engagement of a clutch.

[0073]

According to the present invention, as shown in FIG. 1, even when the shift range of the automatic transmission is set to the forward traveling range, when a predetermined condition is satisfied, a forward clutch is provided. C1 is the control valve 20
A hydraulic control device for an automatic transmission for a vehicle, which is released through a control valve 200 and forms a neutral state to prevent the occurrence of creep. A drain control valve 270 capable of switching between communication between the port and the drain tank 279 and communication between a drain port of the control valve 200 and an oil passage in which the line pressure PL is generated in the forward traveling range. A first control means for switching control of the drain control valve 270 by a control oil pressure applied to the control valve 200, and a switching control of the drain control valve 270 in a system different from the first control means. Second control means for performing By a, it is obtained by solving the above problems.

[0074]

In the hydraulic control device according to the present invention, two means for controlling the drain control valve 270 are provided in separate systems. Therefore, for example, even if the first control means fails, the drain control valve is switched by the second control means, which is different from the first control means, so that the state of the control valve 200 is not affected. Instead, the forward clutch is communicated with an oil passage in which line pressure is generated in the forward travel range, and can perform forward travel.

[0075]

An embodiment of the present invention will be described below with reference to the drawings.

In the following, only portions different from the above-described prior art (shown by thick lines in FIGS. 2 and 3) will be described, and the same portions will be denoted by the same reference numerals and description thereof will be omitted.

FIG. 2 is a circuit diagram of a hydraulic control device for an automatic transmission according to the embodiment, and FIG. 3 is a circuit diagram of a main part thereof. In the device of this embodiment, an ON-OFF solenoid valve 40 is newly added.
0 is provided.

The ON-OFF solenoid valve 400 is
The ON / OFF operation controls the oil pressure of the oil passage 410 to a high pressure or a low pressure (drain). Oil passage 41
Numeral 0 is connected via a throttle 411 and an oil passage 412 to an oil passage 126 that is adjusted to a line pressure PL by a primary regulator valve 124.

The drain control valve 270 has two control signal input (pilot) ports 277 and 278 for switching control of its own spool position in the same direction, and at least one of the ports 277 and 278.
When a hydraulic pressure higher than the set pressure is introduced to the port 278, it is located at the right half position in FIG.
6 to 274. Also, both ports 277, 2
When both pressures at 78 are lower than the set pressure, it is located in the left half position of FIG.
The port 272 is communicated with the drain tank 279.

The one port 277 is connected to an oil passage 320 via an oil passage 332, and the pressure Ps for controlling the C1 control valve controlled by the linear solenoid valve 240 is introduced into the port 277. ing.

The other port 278 is connected to the oil passage 410 via the oil passage 413, and the port 278 is
The hydraulic pressure controlled by the OFF solenoid valve 400 is introduced.

The port 196 for inputting the control signal of the B1 control valve 180 is not a means for generating a throttle pressure, but an ON-OFF solenoid valve 400.
Is connected via an oil passage 414 to an oil passage 410 whose pressure is controlled by the oil passage.

Here, the linear solenoid valve 24
0, oil passage 320 and oil passage 332 correspond to first control means for switching control of drain control valve 270 and are ON.
-OFF solenoid valve 400, oil passage 410, oil passage 4
Reference numeral 13 corresponds to second control means for switching control of the drain control valve 270.

In the apparatus of the present embodiment, when the linear solenoid valve 240 and the modulator valve 250 function normally and the pressure Ps maintains a normal value, the same function as described above is performed.

On the other hand, when the linear solenoid valve 240 or the modulator valve 250 fails, the pressure Ps
If a situation occurs where the value falls below the normal value,
If the pressure Ps is reduced as it is, the drain control valve 270 will be located at the left half position in FIG. 2, and the communication state of the ports 274 and 276 cannot be maintained. Becomes

However, before such a state is reached, after a decision is made that the foot brake is OFF, O
Activate the N-OFF solenoid valve 400 and set the oil passage 4
The hydraulic pressure in 10 is increased. As a result, the line pressure PL is introduced into another control port 278 of the drain control valve 270, and the drain control valve 27
0 is in the right half of FIG. As a result, the line pressure PL from the D range port 116 of the manual valve 110 is led to the drain port 216 of the C1 drain control valve 270.
Since the zero pressure reducing function is depressed and the engagement pressure of the clutch C1 is not reduced, the vehicle can travel forward.

When the pressure Ps drops below the normal value, the pressure introduced into the port 194 of the B1 control valve 180 decreases, causing the B1 control valve 180 to engage the brake B1. 2 (the left half position in FIG. 2). That is, when the second speed of the D range is set in this state, the D range line pressure PL from the port 150 of the 2-3 shift valve 140 is set.
Passes through the oil passage 306 and the ports 186 and 188 of the B1 control valve 180 and further passes through the check valve 17.
0, oil passage 314, port 1 of 1-2 shift valve 130
The brake B1, which is introduced to the brake B1 via the wheels 36 and 138 and is not to be engaged in the D range, is instantaneously engaged.

As a result, in the D range state, when the upshift from the first gear to the second gear is performed, the one-way clutch F2, which is the reaction element of the first gear, is moved from the one-way clutch F2 to the reaction element of the second gear. The "clutch-to-clutch" switching to the one-way clutch F1 can be controlled at a predetermined timing, and the brake B1 should not be engaged, but instantaneously when the second speed signal is output. The brake B1 for the engine brake is engaged, so that the original smooth shifting cannot be performed. As a result, the torque drop due to the engagement of the brake B1 becomes large, and the shift time is instantaneous, so that a strong shift shock occurs.

Similarly, during a manual shift from the D range to the S range (= 2 range), the operating pressure applied to the brake B1 is not the second coast modulator pressure, which is lower than the line pressure, but the line pressure. It will be great.

However, in the apparatus of this embodiment, the ON-OF
Since high pressure oil pressure can be applied to the control port 196 of the B1 control valve 180 by the F solenoid valve 400, the B1 control valve 180 must be held at the switching position on the brake B1 non-engagement side before the above situation occurs. Can be. Therefore, the same function as in the normal state can be guaranteed.

In the above-described embodiment, the linear solenoid valve 240 has a characteristic in which the output pressure Ps decreases as the duty ratio increases. However, the linear solenoid valve 240 increases the duty ratio. At the same time, the output pressure Ps may have a characteristic that increases. In this case, the control pressure Ps should be introduced to the C1 control valve from the opposite direction.

[0092]

As described above, according to the present invention, in the automatic transmission employing the creep reduction control, the vehicle can travel forward even if the control valve for executing the creep reduction control fails. It is possible to prevent the occurrence of a state of disappearing. In addition, since two control means of different systems are provided as switching control means of the drain control valve provided to realize the fail-safe function, even if a failure occurs in one system, the other system may be used. Thus, an excellent effect that a more complete fail-safe function can be provided can be obtained.

Further, even when the first control means fails, forward travel can be ensured by the second control means. Therefore, it is necessary to adopt a configuration in which the drain control valve is switched and controlled by the throttle pressure. In addition, it is possible to avoid a problem when the throttle pressure is used.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the gist of the present invention.

FIG. 2 is a hydraulic control circuit diagram showing a configuration of a device portion for executing basic creep reduction control and hill hold control in one embodiment of the present invention.

FIG. 3 is a hydraulic control circuit diagram schematically showing functions of main parts of the circuit diagram of FIG. 2;

FIG. 4 is a skeleton diagram showing a transmission section of the vehicle automatic transmission in question here.

FIG. 5 is a diagram showing engagement and disengagement states of a friction engagement device at each shift speed in the automatic transmission.

FIG. 6 is a hydraulic control circuit diagram showing a configuration of a device portion for performing conventional basic creep reduction control and hill hold control.

FIG. 7 is a hydraulic control circuit diagram schematically showing functions of main parts of the circuit diagram of FIG. 6;

FIG. 8 is a diagram showing hydraulic characteristics of the above device.

FIG. 9 is a hydraulic control circuit diagram showing a main part of the prior art of the present invention.

[Explanation of symbols]

C1 ... clutch (forward clutch), B1 ... brake (brake to be engaged during hill hold control), 110 ... manual valve, 180 ... B1 control valve, 200 ... C1 control valve, 240 ... linear solenoid valve (first control means) 270: drain control valve; 400: ON-OFF solenoid valve (main element of the second control means).

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-88055 (JP, A) JP-A-2-125165 (JP, A) JP-A-61-235243 (JP, A) JP-A-63-1988 106449 (JP, A) JP-A-4-140570 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (1)

(57) [Claims] When a predetermined condition is satisfied, a forward clutch is released via a control valve to form a neutral state even when the shift range of the automatic transmission is set to a forward traveling range. A hydraulic control apparatus for an automatic transmission for a vehicle, which prevents creep from occurring, comprising: a communication port between a drain port of the control valve and a drain tank, a drain port of the control valve; A drain control valve capable of switching between communication between oil passages in which a line pressure is generated in a forward traveling range; and as a switching control means of the drain control valve, the drain control valve is controlled by a control oil pressure applied to the control valve. First control means for performing switching control; Hydraulic control device for the control means and another system at the drain control vehicular automatic transmission and a second control means for switching control of the valve, comprising the to.