JP3052218B2 - Creep 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 creep control device for a vehicular automatic transmission, which is configured to execute a creep control of a vehicle in a forward traveling range.

[0002]

2. Description of the Related Art An automatic transmission for a vehicle generally includes a hydraulic torque converter that receives rotational power from an engine, and a gear transmission that receives rotational power from the hydraulic torque converter. Is switched in accordance with a predetermined shift pattern in accordance with the vehicle speed and the depression amount of the accelerator opening.

As is well known, a drive range, a neutral range, a parking range,... When the shift range is set to the drive range, so-called creep occurs in which the vehicle moves forward little by little.

[0004] When the drive range is set, the gear transmission is set to the first speed state and the engine is rotating at the idle speed, so that a slight torque is applied to the wheels via the torque converter. Because it is transmitted.

The creep phenomenon can be eliminated by setting the shift range to the neutral range. However, the shift range is maintained at the drive range during running, particularly when starting and stopping are performed frequently. It is common to suppress this creep phenomenon by foot brake.

In view of such a point, there has been conventionally proposed a technique in which even when the shift range is the drive range, a neutral state is formed when a predetermined condition is satisfied to prevent creep. Have been.

More specifically, the predetermined condition is often when the accelerator pedal is released, the foot brake is depressed, and the vehicle speed is detected to be substantially zero.

In order to form the neutral state,
Specifically, the forward clutch (the clutch that is engaged when performing forward running) is slid.

By executing such creep control, the occurrence of creep is prevented, the vibration during idling is reduced, and the fuel consumption efficiency during idling is prevented from deteriorating due to dragging of the torque converter. Will be able to

When the condition for executing the creep prevention control is not satisfied and the creep prevention control is canceled, a load due to the drag of the torque converter is applied to the engine which has been close to no load. Therefore, a phenomenon occurs in which the engine rotation speed temporarily decreases. This phenomenon may lead to engine stall when adverse conditions are overlapped, so some countermeasures must be taken.

In Japanese Patent Application Laid-Open No. 60-250353, the idle speed of the engine during the creep prevention control is controlled to be higher than the idle speed during the non-creep control. There is disclosed a technique that prevents an instantaneous decrease in engine rotation speed due to the action of power steering or the like, and prevents engine stall even if a drag load of a torque converter is applied when creep prevention control is canceled.

In Japanese Patent Application Laid-Open No. 60-60353, when it is determined that the condition for executing the creep prevention control is not satisfied, that is, when the creep prevention control is released, the driver of the idle-up actuator is driven. There is disclosed a technique for giving an instruction to idle up an engine.

[0013]

However, the method of setting the idling rotational speed higher during the creep prevention control as in the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 60-250353 does not employ the creep prevention control. There is a problem that it is not possible to satisfactorily achieve the reduction of the vibration of the vehicle and the improvement of the fuel efficiency, which are one of the main objects of the invention.

Further, the method of idling up the engine at the time of canceling the creep prevention control as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 60-60353 discloses a method in which the time between the engagement of the forward clutch and the idle-up is reduced. If the timing is slightly deviated, there is a problem that an overshoot of the idle-up (injection of the engine) occurs instantaneously, which may give the driver a feeling of strangeness or discomfort.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and suppresses the engine speed during the creep prevention control to reduce the vibration of the vehicle during the creep prevention control and improve the fuel efficiency. The present invention has been made to solve the above-mentioned problem by providing a technique for preventing the engine speed from decreasing and causing engine stall when the creep prevention control is canceled.

[0016]

SUMMARY OF THE INVENTION As shown in FIG. 1, the present invention provides an automatic transmission which can be used when a predetermined condition is satisfied even when a shift range of an automatic transmission is set to a forward traveling range. In a creep control device for an automatic transmission for a vehicle configured to form a neutral state to prevent creep, an idle speed of the engine during the creep prevention control may be equal to an idle speed during non-control. Means for controlling, means for detecting whether or not the cause when the predetermined condition is not satisfied is intended to be a sudden start; and for causing when the predetermined condition is not satisfied, If the intention is to release the creep prevention control by controlling the hydraulic pressure at a high speed, the cause when the predetermined condition is not satisfied is a sudden start. When there is provided with the means for releasing the anti-creep control is controlled at a slower rate while raw hydraulic, is obtained by solving the above problems.

[0017]

According to the present invention, the engine is controlled so that the idling rotational speed during the creep prevention control is equal to the idling rotational speed during the uncontrolled operation. As a result, compared to the technique of setting the engine rotation speed higher than necessary, one of the original purposes of the creep prevention control is to reduce the vibration of the vehicle,
Fuel economy can be reliably improved.
Further, since the engine rotation sound is always constant, the driver does not feel uncomfortable.

In addition, according to the present invention, it is determined whether or not the cause when the predetermined condition for executing the creep prevention control is not satisfied is a sudden start. In this determination, for example, when a predetermined condition is not satisfied by turning off the idle contact, it is determined that sudden start is intended. In addition, when it is detected that the depression amount or the depression speed of the accelerator pedal is equal to or more than a predetermined value, it is determined that sudden start is intended. And the like.

When it is determined that sudden start is intended, the oil pressure is controlled at a high speed to cancel the creep prevention control. As a result, the automatic transmission immediately enters the first speed state, so that a starting posture with good responsiveness can be formed. In addition, since the accelerator pedal is depressed, the driving force of the engine itself is increased, and the problem of engine stall does not occur. Furthermore,
When the driving force is strong, the engagement is performed with a minimum slip, so that the durability of the forward clutch can be improved.

On the other hand, when it is determined that the sudden start is not intended, the creep prevention control is released by controlling at a low speed while smoothing the hydraulic pressure. As a result, the forward clutch is slowly engaged, so that the load torque of the torque converter is gradually applied to the engine, and there is no sudden decrease in the engine rotation speed, and no engine stall occurs. Further, it is possible to prevent the occurrence of a shock at the time of canceling the creep prevention control.

[0021]

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

FIG. 2 shows an overall outline of an automatic transmission for a vehicle to which the embodiment of the present invention is applied.

This automatic transmission has a torque converter 20
, An overdrive mechanism 40, and an underdrive mechanism 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. The output of the crankshaft 10 of the engine 1 is
Transmit to 0.

The lock-up clutch 24 is engaged when conditions are satisfied, and connects the pump 21 and the turbine 22. As a result, fuel consumption efficiency is improved.

The overdrive mechanism has a set of planetary gear units including a sun gear 43, a ring gear 44, a planetary pinion 42, and a carrier 41. The rotational state of the planetary gear unit is determined by a clutch C0 and a brake B0.
, And is controlled by 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 are controlled by clutches C1, C2, brakes B1 to B3, and one-way clutches F1, F2.

Since the specific configuration of the transmission portion of this automatic transmission is well known per se, only the skeleton is shown in FIG. 2 and detailed description is omitted.

This automatic transmission includes the above-described transmission unit and the computer 84. The computer 84 includes a throttle sensor 80 with an idle switch for detecting the throttle opening θ for reflecting the load of the engine 1, a vehicle speed sensor (rotation speed sensor for the output shaft 70) 82 for detecting the vehicle speed N0, and a foot brake. A foot brake switch 90 for detecting that the switch has been turned on,
Engine speed sensor 9 for detecting engine speed
2. Signals for various controls such as an engine coolant temperature sensor 94 and a shift range sensor 99 for detecting a shift range are input.

The computer 84 drives and controls the solenoid valves S1 and S2 in the hydraulic control circuit 86 in accordance with a preset throttle opening-vehicle speed shift point map, and each clutch and brake as shown in FIG. The shift is executed by performing a combination of engagements such as.

In this automatic transmission, as apparent from FIG. 3, the clutch C1 corresponds to a forward clutch that is slipped during creep control. That is, when the shift range is in the forward running range, the forward clutch C1
Are in the engaged state at any of the gear positions, and thereby, the vehicle can travel forward.

However, in this embodiment, when the throttle opening θ is zero (or the idle contact is on), the brake pedal is depressed, and the vehicle speed is zero (including substantially zero), the vehicle is driven in the forward traveling range. Even if this occurs, the engagement pressure of the clutch C1 is reduced, and the automatic transmission is in a neutral state.

In order to execute the creep control, a well-known duty relay Sd (or a linear solenoid) capable of arbitrarily controlling the engagement pressure of the forward clutch C1 is interposed in the hydraulic path of the forward clutch C1. I have.

In this embodiment, when a predetermined signal is sent from the computer 84 to the duty solenoid Sd, a sudden start is intended when the creep prevention control is released and the forward clutch C1 is engaged. The engagement pressure is controlled to be smooth depending on whether or not the engagement is performed, or the engagement pressure is stopped to immediately complete the engagement.

Since the configuration for arbitrarily controlling the rise of the engagement pressure by means of the duty relay Sd is widely known in the past, a detailed description of the configuration will be omitted here.

On the other hand, the engine 1 is controlled by an engine control computer 96 such that its ignition timing and fuel injection amount are controlled so that a predetermined output is obtained.

Here, reference numeral 95 in the figure is a known idle speed control valve, which is disposed in a bypass passage of the intake system. When the opening degree of the control valve 95 is commanded by a computer 96, the idle speed is reduced. It can be controlled.

In this embodiment, the idle speed is controlled to a target value as shown in FIG. As is apparent from the figure, the idle speed is set to be the same regardless of whether creep prevention control is being executed or not, according to the on / off state of the air conditioner and the on / off states of various electric loads. For this reason, there is no change in the engine rotation sound whether the anti-creep control is being performed, or whether or not the anti-creep control is performed. As a result, it is possible to reduce the vibration of the vehicle during the creep prevention control and improve the fuel efficiency.

Next, a specific control flow executed in the apparatus of this embodiment will be described.

In FIG. 4, steps 201 to 206 correspond to steps for judging the conditions for establishing the creep prevention control according to the present invention.

That is, in this embodiment, the shift range is the drive range (step 201), the idle contact signal is on (step 202), the foot brake signal is on (step 203), and the vehicle speed V is less than or equal to a predetermined value V0 close to zero. (Step 20
4) The engine speed Ne is equal to or less than a predetermined value Neo (step 2).
05), the engine coolant temperature T is equal to or higher than a predetermined value T0 (step 20).
6) When all of the conditions are satisfied, the creep prevention control is executed.

Here, the conditions (1) to (4) correspond to conditions for substantially realizing the creep prevention control, and the conditions (4) to (4) correspond to conditions detected for confirmation from the viewpoint of fail-safe.

When all of these conditions are satisfied, the routine proceeds to step 208, in which the forward clutch C1 is released, a neutral state is formed, and a creep preventing state is set.

On the other hand, if it is determined that any one of the steps 201 to 206 does not satisfy the condition, the creep prevention control is released.

In this case, the way of release differs depending on which of the conditions in steps 202 to 206 is not satisfied.

If the condition is not satisfied due to the idle contact not being turned on in step 202,
It is determined that a sudden start is intended, and the routine proceeds to step 212, where the forward clutch C1 is quickly engaged without performing the smoothing control, and the full clutch is directly engaged.

On the other hand, if any of the conditions in steps 203 to 206 is not satisfied, it is determined that sudden start is not intended, and the routine proceeds to step 214, where the forward clutch C1 is first fully engaged. Is determined. Initially, it is determined that full engagement has not yet been achieved, so the routine proceeds to step 218, where the forward clutch C1 is engaged while slowing.

Thus, a small release of the shock can be realized. Also, it is possible to prevent the engine speed from dropping sharply.

When it is determined in step 214 that full engagement has been reached, the process proceeds to step 212, where the full engagement is maintained.

When it is determined that the shift range is not the drive range, the process proceeds to step 213 or step 216. When the shift range is not the drive range, the creep prevention control is not executed. That is, when it is determined that the drive range is not the drive range and the two ranges are determined in the step 213, or the L range is determined in the step 216, it is determined in a step 214 whether the forward clutch C1 is completely engaged. When it is determined that the forward clutch C1 is engaged, the forward clutch C1 is smoothly engaged in step 218. When the forward clutch C1 is fully engaged, the process proceeds from step 214 to step 212, where the forward clutch C1 is completely engaged. Is maintained.

On the other hand, when it is determined that the shift range is not the drive range, 2 range, or L range,
Since it is not in the forward range, the forward clutch C1 is completely released in step 220.

With the above configuration, when the anti-creep control is released by turning on the accelerator pedal, the problem of engine stall does not occur in the first place. Therefore, the responsiveness of starting and the durability of the forward clutch C1 are taken into consideration. As a result, the forward clutch C1 is quickly engaged without smoothing control.

On the other hand, when the creep prevention control is released because the other conditions are not satisfied, the word clutch C1 is slowly engaged while the smoothing control is being performed, so that the shock at the time of release is reduced, and Engine stall is reliably prevented.

As a result, as shown by the one-dot chain line in FIG. 6, in the conventional control for executing the idle-up of the engine together with the release of the creep prevention control, the engine rotational speed Ne sometimes overshoots. However, in this embodiment, such a situation does not occur, and the engine speed can always be stabilized.

In this embodiment, "sudden start"
Is defined as when the idle contact is turned off, but as described above, in the present invention, how to define "sudden start" is limited. is not.

For example, after a negative determination is made in step 202, a step of determining the accelerator pedal depressing speed or the like is provided, and the idle contact is turned off, and only when the accelerator pedal depressing speed is equal to or higher than a predetermined value is " It is also possible to adopt a configuration in which it is determined that the vehicle suddenly starts and the process proceeds to step 212.

[0057]

As described above, according to the present invention, the cause at which the anti-creep control is canceled is determined, and when the cause is intended to suddenly start (the problem of engine stall was originally caused). Since the friction engagement device is rapidly engaged, it is possible to ensure the response of starting. This also improves the durability of the friction engagement device.

On the other hand, when it is determined that sudden start is not intended, the friction engagement device is slowly engaged, so that the shock at the time of canceling the creep prevention control can be reduced, and the engine rotational speed drops rapidly. As a result, the engine stall can be reliably prevented.

[Brief description of the drawings]

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

FIG. 2 is a schematic configuration diagram of an automatic transmission for a vehicle to which an embodiment of the present invention is applied;

FIG. 3 is a diagram showing an operation state of each friction engagement device of the automatic transmission.

FIG. 4 is a flowchart showing a control flow executed by the automatic transmission.

FIG. 5 is a diagram showing a set value of an idle rotation speed.

FIG. 6 is a diagram showing the effect of this embodiment in comparison with a conventional example.

[Explanation of symbols]

 C1: forward clutch, Sd: duty solenoid (for smoothing control), 80: throttle sensor (with idle contact switch), 82: vehicle speed sensor, 84: computer, 90: foot brake switch, 92: engine speed sensor, 94: engine cooling water sensor, 95: idle speed control valve, 99: shift range sensor.

Claims (1)

(57) [Claims] An automatic transmission for a vehicle configured to form a neutral state to prevent creep when a predetermined condition is satisfied even when the shift range of the automatic transmission is a forward travel range. A creep control device for controlling the engine so that an idle rotation speed of the engine during the creep prevention control is equal to an idle rotation speed during the non-creep control; and a cause when the predetermined condition is not satisfied. Means for detecting whether or not a sudden start is intended; and, when the predetermined condition is not satisfied, when the sudden start is intended, the hydraulic pressure is controlled at a high speed to prevent creep. In addition to canceling the control, if the above-mentioned predetermined condition is not satisfied and the cause of the sudden start is not intended, the control is performed at a low speed while smoothing the hydraulic pressure to perform the clutch. Creep control apparatus for a vehicular automatic transmission, characterized in that it comprises a means for releasing the-loop prevention control, the.