JPH06174079A - Creep control device for automatic transmission of vehicle - Google Patents

Abstract

(57) [Abstract] [Purpose] Even if the control valve that controls the engagement pressure of the forward clutch in order to execute the creep control fails, forward travel is ensured. [Constitution] In a device for reducing the engagement pressure of a forward clutch to prevent creep when a predetermined condition is satisfied, a turbine rotation speed in a neutral range and an automatic transmission are shifted from a neutral range to a forward drive range. When the difference (Nc01-Nc0) from the turbine rotation speed after a predetermined time has elapsed is smaller than the predetermined value (ΔNc0), it is determined as fail and a fail flag F3 is set (steps 741 and 742). Then, depending on the judgment of the failure, the control for reducing the engagement pressure of the forward clutch is prohibited, the relay valve is switched, and the hydraulic pressure is supplied to the forward clutch through the oil passage not passing through the control valve (steps 611 to 615). .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a creep control device for an automatic transmission for a vehicle, and particularly to a forward control when a predetermined condition is satisfied even when a shift range is set to a forward drive range. Creep control of a vehicle automatic transmission that forms a neutral state by releasing a clutch (a clutch that is engaged to achieve forward travel) (including substantial release by reducing hydraulic pressure) to prevent creep from occurring Regarding the device.

[0002]

2. Description of the Related Art Conventionally, in an automatic transmission for a vehicle, when a shift range is set to a forward traveling range such as a drive range (D range), even if the vehicle speed is substantially zero, The gear transmission of the automatic transmission does not enter the neutral state, but is set to the first speed (or the second speed). Therefore, since the output of the internal combustion engine is always transmitted to the output shaft via the torque converter and the forward clutch of the gear transmission, so-called creep occurs, and as a result, the brake pedal is depressed to keep the vehicle stopped. It was necessary to maintain the condition. Further, the drag of the torque converter at this time may cause a problem that the fuel consumption efficiency is deteriorated and further the temperature of the working oil of the torque converter rises.

In view of such a point, a control valve for controlling the hydraulic pressure of the forward clutch is newly provided, and when the accelerator pedal is released and the vehicle is substantially stopped, the shift range is set to the drive range. Even if it is in the forward running range like the above, the forward clutch is released or decompressed through the control valve to automatically form the neutral state to prevent the occurrence of creep and improve the fuel consumption efficiency. In addition, technology that suppresses the temperature rise of the hydraulic oil of the torque converter (hereinafter, this control is called "creep control").
Alternatively, it is known as "neutral control" (for example, Japanese Patent Laid-Open No. 61-278650).

[0004]

By the way, in the automatic transmission for performing such neutral control, when the control valve for controlling the engagement pressure of the forward clutch fails (off stick), hydraulic pressure is supplied to the forward clutch. It disappears and it becomes impossible to drive forward.

The present invention has been made in view of the above-mentioned conventional problems, and when a control valve for controlling the engagement pressure of the forward clutch fails, appropriate measures are taken at an early stage. The above problems are solved by providing a creep prevention control device that prevents an inconvenient situation from occurring.

[0006]

As shown in FIG. 1, the present invention provides a forward clutch when a predetermined condition is satisfied even when the shift range of the automatic transmission is set to the forward drive range. In a creep control device for an automatic transmission for a vehicle, which forms a neutral state by reducing the engagement pressure of the vehicle through a control valve to prevent the occurrence of creep, hydraulic pressure is supplied to a forward clutch through the control valve. The first oil passage,
A second oil passage for supplying hydraulic pressure to the forward clutch without going through the control valve, the first oil passage and the second oil passage.
A switching valve that selectively connects the oil passage of the automatic transmission to the forward clutch, a means for detecting that the automatic transmission has been shifted from the neutral range to the forward drive range, and a turbine rotation of the hydraulic torque converter of the automatic transmission. The means for detecting the speed, the turbine rotation speed in the neutral range (N range), and the turbine rotation speed a predetermined time after the automatic transmission is shifted from the neutral range to the forward travel range (for example, D range). A means for calculating the difference, a means for judging a failure when the difference calculated by the means is smaller than a predetermined value, a prohibition control for reducing the engagement pressure of the forward clutch, and the switching according to the judgment of the failure. Means for switching the valve to connect the second oil passage to the forward clutch is provided to solve the above problems. It is intended.

According to the second aspect of the present invention, as shown in FIG. 2, even when the shift range of the automatic transmission is set to the forward drive range, when the predetermined condition is satisfied, the forward clutch is operated. A creep control device for an automatic transmission for a vehicle, which forms a neutral state by reducing an engagement pressure via a control valve to prevent the occurrence of creep, wherein a hydraulic pressure is supplied to a forward clutch via the control valve. Oil passage 1
A second oil passage for supplying hydraulic pressure to the forward clutch without going through the control valve, the first oil passage and the second oil passage.
A switching valve that selectively connects the oil passage of the automatic transmission to the forward clutch, a means for detecting that the automatic transmission has been shifted from the neutral range to the forward drive range, and a turbine rotation of the hydraulic torque converter of the automatic transmission. A means for detecting the speed, a means for calculating a difference between the turbine rotation speed in the neutral range and a turbine rotation speed after a predetermined time has elapsed after the automatic transmission was shifted from the neutral range to the forward drive range, and the means. When the calculated difference is less than a predetermined value, means for determining a failure, means for detecting a condition that does not cause a sudden start of the vehicle, and a condition for determining a failure and not causing a sudden start of the vehicle are detected, The control for reducing the engagement pressure of the forward clutch is prohibited, and the switching valve is switched to switch the second oil passage to the forward clutch. Means for connecting the switch, by providing the one in which the above-mentioned problems are eliminated.

[0008]

When the automatic transmission is operated in the neutral range, the forward clutch is in the disengaged state (generally the slip state rather than the full disengagement state). Therefore, the turbine rotation speed of the torque converter becomes substantially equal to the engine rotation speed. When the shift operation is performed from the neutral range state to the forward drive range, if normal, the forward clutch is completely engaged by supplying hydraulic pressure after a predetermined time has elapsed. Therefore, the turbine rotation speed of the torque converter becomes lower than the turbine rotation speed in the neutral range (it becomes zero when the vehicle speed is zero).

However, if the control valve that supplies the hydraulic pressure to the forward clutch is failing (off-stick), the hydraulic pressure is not supplied, and the forward clutch does not engage. Therefore, the turbine rotational speed is not reached even after a predetermined time elapses. Will not decrease.

The present invention focuses on this point. That is, when the difference between the turbine rotation speed during the neutral range and the turbine rotation speed after a predetermined time after the automatic transmission is shifted from the neutral range to the forward travel range is smaller than a predetermined value, that is, the turbine rotation speed is If it does not become lower as expected, it is determined that the forward clutch is in a state where it cannot be completely engaged and the control valve is failing.

In that case, the neutral control is prohibited and the hydraulic pressure is supplied to the forward clutch from the oil passage not passing through the control valve. As a result, the forward clutch is engaged regardless of the control valve, and it becomes possible to travel forward.

Since the above-mentioned failure detection is carried out based on the change in turbine rotational speed during the shift operation,
This is possible even when the condition for executing the neutral control (creep control) is not satisfied, for example, when the engine water temperature is low after the engine is started, and the situation where the vehicle cannot travel forward immediately can be avoided.

By the way, when the neutral control is prohibited and the second oil passage side is immediately switched to, the vehicle is ready to start including the creep from that time. Therefore, in the device according to the second aspect of the present invention, even when the fail is detected, the neutral control is prohibited only when the condition that the vehicle does not suddenly start, for example, the condition that the brake is ON and the idle contact is ON, is detected. Switch to the 2 oil passage side. This increases safety.

When a fail judgment is made, it is desirable to display or warn that fact as necessary.

[0015]

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

FIG. 3 is an overall schematic view of an automatic transmission combined with an automobile electronic fuel injection engine.

This automatic transmission has a torque converter section 2
0, overdrive mechanism 40, forward 3 speeds reverse 1
And a stepped underdrive mechanism portion 60.

The torque converter section 20 includes a pump 2
1, a turbine 22, a stator 23, and a lock-up clutch 24 are well-known, and the output of the crankshaft 10 of the engine 1 is supplied to the overdrive mechanism unit 4.
Transmit to 0.

The overdrive mechanism 40 comprises a sun gear 43, a ring gear 44, a planetary pinion 42,
And a set of planetary gears consisting of a carrier 41,
The rotation state of this planetary gear device is controlled by a clutch C0, a brake B0, and a one-way clutch F0.

The underdrive mechanism section 60 is provided with two sets of planetary gear units consisting of 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 section 40 are controlled by the clutches C1 and C2, the brakes B1 to B3, and the one-way clutches F1 and F2.

The computer 84 for controlling the automatic transmission includes a throttle sensor 80 for detecting a throttle opening θ for reflecting the load of the engine 1, a vehicle speed sensor for detecting a vehicle speed N0 (a rotational speed sensor for the output shaft 70). 82,
An Nc0 sensor 99 that detects the rotational speed Nc0 of the clutch C0, a shift position switch 5 that outputs a shift position signal, a brake switch 6 that outputs a signal when the foot brake is stepped on, and a Ne sensor 7 that detects the engine rotational speed Ne. Signals for various controls such as the idle switch 8 for outputting the state of the idle contact, the water temperature switch 9 for detecting the cooling water temperature T of the engine, and the like are input.

The rotation speed Nc0 of the clutch C0 is
From the first speed to the third speed, the torque converter unit 20
Since this is the same as the turbine rotation speed nc0, the Nc0 sensor 99 is used as the turbine rotation speed detection means in this embodiment.

The computer 84 uses the input signals from the respective sensors, switches, etc. as parameters, and in accordance with a preset throttle opening-vehicle speed shift point map, solenoid valves S1, S in a hydraulic control circuit 106 described later.
2, S3, S4 and the like are driven and controlled, and the shift control is performed by engaging the clutches and brakes as shown in FIG.

Here, the clutch C1 corresponds to a forward clutch that is released during the creep reduction control, and the brake B1 corresponds to a hill hold brake that prevents the vehicle from moving backward during the creep reduction control.

When the shift range is in the forward drive range, the forward clutch C1 is in the engaged state, and the forward drive is enabled. Even if the shift range is the forward drive range, if the throttle opening θ is zero (or the idle contact is ON) and the vehicle speed is zero (including substantially zero), the engagement of the forward clutch C1 is When the combined pressure is reduced, the automatic transmission is shifted to the neutral state (creep control), and the brake B1 is engaged to operate the hill hold function (hill hold control).

Next, an example of the hydraulic control device for executing the creep control and the hill hold control will be described with reference to FIG.

In the figure, reference numeral 110 indicates a manual shift valve. This manual shift valve 1
10 has a hydraulic pressure input port 114. The line pressure PL that is sucked up by the oil pump 120 and regulated by the primary regulator valve 124 is supplied to the hydraulic pressure input port 114 through the oil passage 126. The manual shift valve 110 has a spool 112 driven by a manual shift lever (not shown), and connects the hydraulic pressure input port 114 to the D range port 116 when the manual shift range is the D range. When the manual shift range is the S range (2 ranges), the hydraulic pressure input port 114 is connected to the S range port 118.

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

The 2-3 shift valve 140 includes the spool 1
42. The spool 142 is in the raised position shown in the right half of the figure when the hydraulic pressure is not supplied to the port 144, and allows the port 146 to communicate with the port 150.
Moreover, the port 148 is connected to the port 152. On the other hand, when the hydraulic pressure is being supplied to the port 144, it is in the lowered position shown in the left half of the figure, and the communication between the port 146 and the port 150 is blocked and the communication between the port 148 and the port 152 is blocked. , Port 152 communicates with drain port 154.

The supply of the control oil pressure to the port 144 is
Done in a known manner by means of solenoid valve S1,
The hydraulic pressure is supplied to the port 144 only when the speed stage or the overdrive stage (the fourth speed stage) is achieved. Therefore, the spool 142 is in the raised position when the first speed or the second speed is achieved, and is in the lowered position when the third speed or the overdrive speed is achieved.

The solenoid valve S1 is of a normally closed type, and when it is "OFF", the pressure is supplied to the port 144, and when it is "ON", the pressure disappears. Therefore, when the first speed or the second speed is achieved, the solenoid valve S1 is turned on to release the pressure, and when the third speed or the overdrive is achieved, the solenoid valve S1 is turned off to supply the pressure. To do.

The port 150 is provided with an oil passage 306 so that a B1 control valve 18 for hill hold control described later can be provided.
0 port 186. Port 152
Oil passage 308, second coast modulator valve 16
0, through oil passage 310 and port 1 of check valve 170
It is connected to 72.

The check valve 170 has an inlet port 17
In addition to 2, it has another inlet port 174 and one outlet port 176. When the hydraulic pressure is supplied to the inlet port 172 by the action of the check ball 178, the inlet port 174 is closed and the inlet port 174 is closed. The inlet port 172 is closed when the hydraulic pressure is being supplied to the inlet port 172. The inlet port 174 is connected to the port 188 of the B1 control valve 180 by an oil passage 312, and the outlet port 176 is connected by an oil passage 314 to the 1-
It is connected to the port 136 of the 2-shift valve 130.

The 1-2 shift valve 130 is the spool 13
Have two. When the hydraulic pressure is not being supplied to the port 134, the spool 132 is in the raised position shown in the left half of the figure, and makes the ports 136 and 138 communicate with each other, while when the hydraulic pressure is being supplied to the port 134, the right half of the figure is shown. In the lowered position shown in FIG. 3, the ports 136 and 138 are cut off so that the port 138 communicates with the drain port 139.

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

At the port 134, the solenoid valve S2
The hydraulic pressure is supplied when the 1st speed stage and the overdrive stage are achieved by the action of
C2 hydraulic pressure is supplied to 37, which causes 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.

This solenoid valve S2 is also a normally closed type, and when it is "OFF", the port 134
Is supplied to, and when "ON", the pressure disappears.

The relationship between the operation signals to the solenoid valves S1 and S2 and the shift speed is shown in the table below.

[0039]

The B1 control valve 180 provided for hill hold control includes a spool 182 and a plug 18
4 and. When the spool 182 is in the raised position shown in the right half of the drawing, the ports 186 and 188 communicate with each other, and the ports 190 and 192 are cut off so that the port 1
92 is connected to 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 so that the port 188 communicates with the drain port 187, and the ports 190 and 192 communicate with each other.

The port 190 is connected to the oil passage 314 and the 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 provided for neutral control (creep reduction control) by the oil passage 316.

The spool 182 of the B1 control valve 180 is driven by the hydraulic pressure applied to the ports 194 and 196, and when the signal hydraulic pressure Ps of a predetermined value Psset or more is supplied to at least one of the ports 194 and 196, the left half position is set. That is, it is located at the hill hold control release position. Further, when the signal hydraulic pressure Ps equal to or higher than the predetermined value Psset is not supplied to any of the ports 194 and 196, it is located at the right half position, that is, the hill hold control position. Port 194 is oil passage 318
Is connected to the oil passage 320 to supply the signal oil pressure Ps of the oil passage 320.

The solenoid valve S3 provided as the main control means of the C1 control valve 200 for neutral control and the B1 control valve 180 for hill hold control is in accordance with the duty ratio D of the pulse signal given to its electromagnetic coil. The signal pressure Ps corresponding to the duty ratio D is generated in the oil passage 320. The solenoid valve S3 is constituted by a so-called normally closed solenoid valve, whereby the signal oil pressure Ps of the oil passage 320 decreases as the duty ratio D given to the electromagnetic coil increases. Oil passage 32
0 is throttle 280, oil passage 322, modulator valve 25
0, the oil pressure is connected to the oil path 126 via the oil path 324, whereby the oil pressure 322 is supplied to the oil path 322 with the modulated hydraulic pressure Pm adjusted to a predetermined constant pressure by the modulator valve 250.

The oil passage 320 is connected to the port 194 of the B1 control valve 180 by an oil passage 318, 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.
The spool 202 is connected to the oil passage 3 by the oil passages 328 and 314.
21 connected to 00 and supplied with line pressure PL
By controlling the degree of communication between the second drain port 216 and the drain port 216, the hydraulic pressure of the outlet port 214 is adjusted. This pressure adjustment value increases in accordance with the urging force applied to the spool 202 by the compression coil spring 218 and the increase in the pressing force directly applied to the spool 202 by the plugs 204 and 206. Exit port 214
Is connected to the clutch C1 via a C1 relay valve (switching valve) 270 provided for fail-safe of the C1 control valve 200.

That is, the C1 relay valve 270 is arranged between the port 214 of the C1 control valve 200 and the clutch C1. Then, the port 214 of the C1 control valve 200 and the C1 relay valve 270
Port 272 is connected by an oil passage 330. Further, the clutch C1 and the port 276 of the C1 relay valve 270 are connected by the oil passage 340. Further, the D range line pressure PL generated at the D range port 116 of the manual valve 110 is guided to the port 274 of the C1 relay valve 270 by the oil passage 336.

As a result, the C1 control valve 20
A first oil passage for supplying hydraulic pressure to the clutch C1 via 0 and a second oil passage for supplying hydraulic pressure to the clutch C1 without passing through the C1 control valve 200 are formed.

A throttle 284 is provided in the middle of the oil passage 340.
Is provided. The oil passage 340 and the oil passage 300 are
It is connected via a check valve 260. The check valve 260 is configured to allow only the oil flow from the oil passage 340 to the oil passage 300, that is, the oil drain flow.

The hydraulic control system of this embodiment is further provided with another solenoid valve S4. The solenoid valve S4 is turned on / off to control the hydraulic pressure of the oil passage 410 to a high pressure or a low pressure. The oil passage 410 is connected to an oil passage 126 whose line pressure PL is adjusted by the primary regulator valve 124 via the throttle 411 and the oil passage 412.

The C1 relay valve 270 has two control signal input (pilot) ports 277 and 278 for controlling the spool position of the C1 relay valve 270 in the same direction. At least one of the ports 277 is provided. , 27
When a hydraulic pressure higher than the set pressure is introduced into the port 8, the port is located at the right half position of FIG.
Communicate with. Further, when the pressures of both ports 277 and 278 are both lower than the set pressure, they are located at the left half position in FIG. 5, and thereby the port 276 is communicated with 272.

The one control signal input port 277.
Is connected to the oil passage 320 via the oil passage 334, and at the port 277, C adjusted by the solenoid valve S3.
1 Pressure Ps for control valve control is introduced. The other control signal input port 27
No. 8 is connected to the oil passage 410 via the oil passage 413, and the hydraulic pressure controlled by the solenoid valve S4 is introduced into the port 278.

The port 196 for inputting the control signal of the B1 control valve 180 is connected to the oil passage 410 whose pressure is controlled by the solenoid valve S4 via the oil passage 414.

Here, the linear solenoid valve S3,
Oil passage 320 and oil passage 334 are first control means for switching control of C1 relay valve 270, and ON-OFF solenoid valve S4, oil passage 410 and oil passage 413 are second control means for switching control of C1 relay valve 270. Are configured.

Further, in this apparatus, the drain port 216 for adjusting the pressure of the C1 control valve 200 is connected to the port 192 of the B1 control valve 180.
1 Control valve 180 is in the brake release position (Fig. 5
The left half position of the), the D range line pressure PL is
It is adapted to be introduced into the drain port 216 together with the control port 208 of the C1 control valve 200.

Next, the operation of the hydraulic control device having the above structure will be described.

When the manual shift range is set to "D range" and the solenoid valve S2 is "OFF",
When the first speed stage is established by turning ON the solenoid valve S1, the 1-2 shift valve 1
The spool 132 of 30 is in the lowered position and the spool 142 of the 2-3 shift valve 140 is in the raised position.

While the creep control and the hill hold control are not yet started and the OFF signal is given to the solenoid valve S3, the signal hydraulic pressure Ps of the oil passage 320 becomes the same hydraulic pressure as the output hydraulic pressure Pm of the modulator valve 250. The set hydraulic pressure is supplied to the port 194 of the B1 control valve 180 and the port 210 of the C1 control valve 200. Therefore, at this time, the spool 180 of the B1 control valve 180 is at the left position,
That is, it is located at the hill hold control release position, whereby the port 186 is closed and the hill hold control output port 188 is connected to the drain port 187.

Further, since 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 via the oil passage 316, and from this, the C1 control valve 2
00 is located at the left side position, that is, the normal mode position due to the action of the line pressure PL supplied to the port 208 in addition to the signal oil pressure Ps given to the port 210.

As a result, the line pressure PL applied to the port 212 is not reduced by completely closing the drain port 216, and is introduced into the clutch C1 through the oil passage 330 from the port 214 as it is. Therefore, at this time, the clutch C1 is completely engaged and the first speed is achieved.

Since the port 186 of the B1 control valve 180 is closed, the port 188 is drain-connected, and the port 13 of the 1-2 shift valve 130 is connected.
Since 6 is also closed and port 138 is drain connected,
No hydraulic pressure is supplied to the brake B1 and the brake B1
Remain open.

Next, under the condition that 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 ON), and the vehicle speed is close to zero. When the value becomes equal to or less than a predetermined value, a control command is issued to each of the solenoid valves S1 to S4 in order to execute the creep control and the hill hold control.

That is, a pulse signal is given to the solenoid valve S3, and its duty ratio D is increased with the passage of time. As the duty ratio D increases, the signal oil pressure Ps of the oil passage 320 gradually decreases with the passage of time, and when the signal oil pressure Ps drops to a predetermined value Psset, the spool 182 of the B1 control valve 180 is moved to the position shown in FIG. To the right side (hill hold control side), and the communication port of port 188 is the drain port 187.
To port 186. Further, the communication port of the port 192 is switched from the port 190 to the drain port 198.

Therefore, since the line pressure PL is not supplied to the port 208, the regulated value of the C1 control valve 200, that is, the engagement pressure of the clutch C1 is set by the signal hydraulic pressure Ps supplied to the port 210, and the signal hydraulic pressure Ps is set.
The drain port 216 comes to be opened with the decrease of. As a result, the engagement pressure supplied from the port 214 to the clutch C1 is reduced, which causes the clutch C1 to slip. As a result, the automatic transmission is brought into a state similar to that in the neutral state, idle vibration is reduced and at the same time creep is prevented from occurring. That is, the creep control is executed.

At the same time, at the same time, both solenoid valves S1 and S2 are turned "ON" in order to achieve the second speed state.
Operated. 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 solenoid valve S1 is turned "ON" so that the spool 142 of the 2-3 shift valve 140 is in the raised position, that is, the first speed. The manual shift valve 11 is operated by being operated to a switching position that achieves the second speed or the second speed
The line pressure PL of the D range port 116 of 0 is the oil passage 30.
0, 302, 2-3 shift valve 140 port 146
And 150, oil passage 306, B1 control valve 18
0 through the ports 186 and 188, the oil passage 312, the check valve 170, and the oil passage 314, and the 1-2 shift valve 13
0 to port 136.

Then, the solenoid valve S2 is turned "ON".
As a result, the spool 132 of the 1-2 shift valve 130 is operated to the raised position, that is, the switching position for achieving the second speed, the third speed, or the overdrive stage (4th speed), and thus the port 136 is reached. Line pressure PL reached
Is supplied from the port 138 to the brake B1 via the oil passage 316, the brake B1 is engaged, and the sun gear 61 (see FIG.
(See) will be fixed. Therefore, sun gear 6
Since the reverse rotation of the carrier 67 is blocked by the fixing of No. 1 and the action of the one-way clutch F2, the planetary pinion 65 is blocked by the reverse rotation of the gear 67.
The reverse rotation of No. 3 is prevented, the output shaft 70 is prevented from rotating in the backward direction of the vehicle, and so-called hill hold control is executed.

That is, even when the manual shift range is the "D range", the brake B1 is engaged to achieve the same shift speed as the second speed of the "S range". , The backward movement of the vehicle is prevented.

By the way, although the above description is for the case where the above hydraulic control devices are all functioning normally, among these elements, especially when the C1 control valve 200 fails (off-stick). May have the inconvenience of being unable to move forward.

Therefore, in the apparatus of the present embodiment, when such a situation may occur, a fail judgment is made, the neutral control is prohibited based on the judgment, and the C1 relay valve 270 is turned on. The function to switch the line pressure directly to the clutch C1 is incorporated.

When the C1 control valve 200 fails, the output pressure P of the linear solenoid valve S3
As long as s rises above a specified value, C1 relay valve 270
Since the line pressure PL from the D range port 116 of the manual valve 110 is guided to the clutch C1 via the ports 274 to 276 and the oil passage 340, the vehicle can travel forward.

As the control pressure of the C1 relay valve 270, a throttle pressure may be added in addition to this.
As a result, the higher the throttle pressure Pth, the faster the C1 relay valve can be switched, and the more quickly the line pressure from the D range port 116 of the manual valve 110 can be guided to the clutch C1. Even if the solenoid valve S3 fails, the accelerator pedal can be depressed (the throttle pressure can be increased) to allow the vehicle to travel forward.

The fail-safe function will be described in detail below with reference to the flowchart of FIG. Prior to the description of the contents of the flowcharts, the meanings of symbols and flags used in each flowchart will be described. The symbols and flags have the following meanings.

Nc01 = Turbine rotation speed in N range nc0 = actual turbine rotation speed F1 = Flag indicating that the clutch is completely engaged due to neutral control start-return F2 = To perform hill hold control 2 Flag F3 indicating that the solenoid valve S2 is in the ON state in order to achieve the speed state F3 = Flag indicating a state in which a failure has occurred =
Flag for canceling neutral control F4 = Flag indicating feedback control in neutral control F5 = Sweep mode state (mode in which clutch hydraulic pressure is gradually reduced) before starting neutral control and entering feedback control Flag indicating that there is F01 = Flag indicating that it is in the N range F02 = Flag indicating that the clutch C1 is in a state until it is completely engaged after the N → D shift

FIG. 6 shows the contents of creep control including the fail-safe function. This routine is repeatedly executed periodically, and when this routine is started, the conditions for establishing the creep prevention control are determined in steps 600 to 606. The conditions are as follows.

Shift range is drive range (step 600) Idle contact signal is on (step 601) Fail flag F3 is "0" (step 602) Foot brake signal is on (step 603) Vehicle speed V is a predetermined value V0 close to zero Below (step 604) The engine rotation speed Ne is below a predetermined value Ne0 (step 605) The engine cooling water temperature THW is above a predetermined value T1 (step 606) When all of these conditions are met, the creep prevention control is executed.

Here, the conditions of ,, and correspond to the conditions for substantially fulfilling the creep prevention control, and the conditions of and correspond to the conditions detected for confirmation from the viewpoint of fail-safe. The condition of is a condition indicating the presence or absence of fail safe.

If all these conditions are met, step 60
Proceed to 7 to execute neutral control. Then, in step 608, a flag F1 indicating that neutral control has been started is set, in step 609 an ON signal is output to the solenoid valve S2 to engage the hill hold brake, and in step 610, hill hold is in progress. The flag F2 shown is set, and in step 730, the N range flag F01 is reset to "0".

On the other hand, if any of the steps 600 to 606 determines that the condition is not satisfied, the creep prevention control is prohibited or released. In this case, steps 600-60
How to cancel depends on which condition out of 6 is not satisfied.

When the creep prevention control is prohibited or canceled by the condition of step 601, that is, when the idle contact is turned off (depressing the accelerator pedal),
The routine proceeds to step 611, where it is checked whether or not the flag F2 indicating that the hill hold is in progress is set. If the flag F2 is set, it is determined in step 612 whether or not the vehicle speed is equal to or lower than the predetermined value V1, and if the vehicle speed is equal to or lower than V1, the signal to the solenoid valve S2 is turned off in step 613 to perform the hill hold control. To stop. Then,
In step 614, the flag F2 is reset, and in step 6
Fully engage the forward clutch at step 15, step 6
At 16, the flag F1 indicating the neutral control state is reset. Then, in this case, the process proceeds to step 731 and N
→ Reset the flag F02 indicating the D shift mode to "0".

If it is determined in step 611 that the flag F2 is not set (NO), or if it is determined in step 612 that the vehicle speed is not equal to or lower than the predetermined value V1, step 613 is jumped to step 6
Proceed to 14.

If the creep control is stopped because the condition of step 602 is not satisfied, that is, if the flag F3 indicating that some failure has occurred in the hydraulic control device is set, the process proceeds to step 611, and thereafter. In the process of (1), the neutral control is prohibited, and the clutch C1 is completely engaged by operating the relay valve.

On the other hand, the creep prevention control is step 603.
If any of the above items (1) to (606) is prohibited or canceled due to the failure, the process proceeds to step 732.

In step 732, it is determined whether or not the shift range was the N range up to the previous time by the flag F01. If F01 = 1, the flag F02 = 1 is set in step 733 to execute the N → D shift, and step 734. Then, the timer t is set to "0". Next, at step 735, it is judged by the flag F02 whether or not it is the N → D shift mode. When F02 = 1, the routine proceeds to step 621.

If not completely engaged, the clutch C1 is gradually engaged in step 622, and the process proceeds to step 739. In step 739, it is determined whether the N → D shift mode is set. When it is determined that the mode is the N → D shift mode, it is determined in step 740 whether the time after the N → D shift is the predetermined value t02 or more.
At 1, it is determined whether the deviation between the turbine rotation speed Nc01 and the actual turbine rotation speed Nc0 in the N range is less than or equal to a predetermined value ΔNc0.

If it is less than the predetermined value, that is, if the change in turbine rotation does not decrease even after the predetermined time t02 has elapsed, it is determined that the control valve has failed (off-stick), and in step 742, the fail flag F3 =
Set to 1.

On the other hand, if it is determined in step 621 that the clutch C1 is completely engaged, then in step 736 N →
If it is in the N → D shift mode, that is, in the case of F02 = 1, it is determined whether or not the D shift mode is selected.
At, it is determined whether the time from the N → D shift to the complete engagement of the clutch C1 is a predetermined value t01 or less. If the time is less than or equal to the predetermined value, it is determined that the control valve has failed, and the fail flag F3 = 1 is set in step 738. That is, when the engagement is completed in a very short time (the line pressure PL seems to be input immediately), the control valve is determined to be fail (on-stick).

In summary, steps 736-738
In step 73, the on-stick of the control valve is detected depending on whether the hydraulic pressure of the clutch C1 is equal to the line pressure.
9 to 742 detects the off stick of the control valve depending on whether or not the oil pressure of the clutch C1 is zero.

On the other hand, if the N → D shift mode is not set,
If the determination in step 735 is no, the process proceeds to step 618 to determine the state of the flag F1. If the flag F1 has not been set, the process proceeds to step 619 to determine the state of the flag F2. If the flag F2 is not set, the process proceeds to step 614.

If the flag F2 is set, it is judged in step 736 whether the flag F02 = 1 or not, and NO.
In the case of, it is determined in step 620 whether or not the vehicle speed is equal to or lower than the predetermined value V1, and in the case of NO, the routine proceeds to step 614 and YES.
In the case of, the process proceeds to step 615.

If the flag F1 is set, the determination in step 618 is YES and step 6
At 21, it is judged whether the clutch is completely engaged,
In the case of YES, the process proceeds to step 736, and in the case of NO, the process proceeds to step 622 to gradually engage the clutch.

If it is determined that the shift range is not the drive range, the process proceeds to step 617 or step 623. Creep control is not executed when the shift range is not the drive range. Therefore, if the range is the 2 range or the L range, the process proceeds to step 732.

On the other hand, when it is determined that the shift range is neither the drive range, the two ranges nor the L range,
Proceeding to step 624, the clutch is fully opened, the flag F1 is reset in step 625, and the flag F2 is reset in step 626. Further, the N range flag F01 = 1 is set in step 743, and the flag F0 is set in step 744.
2 = 0, and the turbine rotation speed Nc0 detected in step 745 is set as the turbine rotation speed Nc01 in the N range.

As described above, even when the neutral control condition is not satisfied, the fail (off-stick) of the control valve is detected according to the change in the turbine rotation speed during the N → D shift, so that the failure can be detected early. Yes, it is possible to always maintain a state in which the vehicle can travel forward.

Next, a second embodiment of the present invention will be described.

FIG. 7 is a flow chart of the second embodiment, and FIG.
Shows the details of one of the steps 800.

In this embodiment, the flag type is divided depending on the fail mode of the control valve, that is, the on-stick or off-stick mode, and different configurations are made to correspond to the respective fail modes.

Specifically, as shown in FIG. 7, when the on-stick of the control valve is detected, the flag F30 = 1 indicating the on-stick is set in step 738A. When the off stick of the control valve is detected, the flag F31 = 1 indicating the off stick is set in step 742A.

These flags have the following meanings: F30 = flag indicating a fail when the fail phenomenon is the same as the normal D range F31 = flag indicating a fail when the fail phenomenon is the same as the neutral state

At the beginning of the flow of FIG. 7, step 800 for determining the N control prohibition time is added, and step 602 for determining the fail flag F3 is omitted because the fail flag F3 is not used in this embodiment. is doing. Since the rest is the same as the flowchart in FIG. 6, the same step numbers are assigned.

In step 800 of N-control prohibition time determination, specifically, the processing is performed in the flow as shown in FIG.

First, at step 801, the flag F30 =
If it is determined that the failure phenomenon is the same as in the normal D range, the process proceeds to steps 614, 615 and 616 to immediately inhibit the N control after the failure is detected and engage the clutch C1.

On the other hand, if the flag F30 = 1 is not satisfied, it is determined in step 802 whether the flag F31 = 1.
When the fail phenomenon is the same as the neutral state, the brake is ON (condition 1) in steps 803 to 806, the idle contact is ON, and the engine speed Ne is the predetermined value Ne1.
It is determined whether or not (condition 2) below, and when all the conditions are satisfied, it is determined that sudden start does not occur, and at this point, the process proceeds to steps 614, 615, and 616 for the first time, and neutral control is prohibited and the clutch C1 Engage.

By doing so, even if the line pressure is supplied to the clutch C1 due to the cancellation of the neutral control, it is possible to prevent the occurrence of creep due to the satisfaction of the conditions 1 and 2.

[0103]

As described above, according to the creep prevention control device of the present invention, it is possible to travel forward even if the control valve fails. Moreover, since this failure can be detected before the creep control is executed, it can be dealt with early.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing the gist of the invention of claim 2.

FIG. 3 is a schematic configuration diagram of an entire system including an automatic transmission to which an embodiment of the present invention is applied.

FIG. 4 is a view showing an engaged / disengaged state of a friction engagement device at each shift stage in the automatic transmission.

FIG. 5 is a diagram showing a structure of a hydraulic control device for an automatic transmission according to the above-described embodiment.

FIG. 6 is a flowchart showing the control contents in the embodiment.

FIG. 7 is a flowchart showing the control contents of another embodiment.

FIG. 8 is a step 800 in the flowchart of FIG.
Flowchart showing details of contents

[Explanation of symbols]

 C1 ... Forward clutch 20 ... Torque converter 22 ... Turbine 200 ... C1 control valve 270 ... C1 relay valve (switching valve)

Claims (2)

[Claims] 1. A neutral position is obtained by reducing an engagement pressure of a forward clutch via a control valve when a predetermined condition is satisfied even when a shift range of an automatic transmission is set to a forward drive range. A creep control device for an automatic transmission for a vehicle, which forms a state to prevent occurrence of creep, comprising: a first oil passage for supplying hydraulic pressure to a forward clutch via the control valve; and a forward oil passage not via the control valve. A second oil passage for supplying oil pressure to the clutch, a switching valve for selectively connecting the first oil passage and the second oil passage to a forward clutch, and an automatic transmission from a neutral range to a forward travel range. A means to detect that the shift operation has been performed and a turbine rotation speed of the hydraulic torque converter of the automatic transmission Means for calculating the difference between the turbine rotation speed during the neutral range and the turbine rotation speed for a predetermined time after the automatic transmission shifts from the neutral range to the forward drive range, and the calculation by the means. When the difference is smaller than a predetermined value, it is determined as a failure, and in accordance with the determination of the failure, the reduction control of the engagement pressure of the forward clutch is prohibited, and the switching valve is switched to switch the second oil passage to the forward clutch. A creep control device for an automatic transmission for a vehicle, comprising: 2. The neutral pressure is reduced by reducing the engagement pressure of the forward clutch through the control valve when a predetermined condition is satisfied even when the shift range of the automatic transmission is set to the forward drive range. A creep control device for an automatic transmission for a vehicle, which forms a state to prevent occurrence of creep, comprising: a first oil passage for supplying hydraulic pressure to a forward clutch via the control valve; and a forward oil passage not via the control valve. A second oil passage for supplying oil pressure to the clutch, a switching valve for selectively connecting the first oil passage and the second oil passage to a forward clutch, and an automatic transmission from a neutral range to a forward travel range. A means to detect that the shift operation has been performed and a turbine rotation speed of the hydraulic torque converter of the automatic transmission Means for calculating the difference between the turbine rotation speed during the neutral range and the turbine rotation speed for a predetermined time after the automatic transmission shifts from the neutral range to the forward drive range, and the calculation by the means. When the difference is smaller than a predetermined value, a means for judging a failure, a means for detecting a condition that does not cause a sudden start of the vehicle, and a condition for judging a failure and not causing a sudden start of the vehicle, the forward clutch And a means for connecting the second oil passage to the forward clutch by prohibiting the engagement pressure reduction control described in 1. above, and a creep control device for an automatic transmission for a vehicle.