JP2004052809A - Control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a vehicle capable of eliminating giving a sense of discomfort to any driver or passenger owing to a shock when the driver's foot is released from an accelerator pedal during the smooth lockup control in the low vehicle speed range and of enhancing the performance about the fuel consumption. <P>SOLUTION: In case the lockup differential pressure command value has become greater than the specified reference value LUSO when a foot release is conducted during the smooth lockup control, transition to the lockup disengagement due to insufficient capacity is precluded by increasing the lockup differential pressure command value at ▵LUS intervals until the value becomes a predetermined higher set value. At the time of foot release, a trigger signal is emitted to an engine control unit, and the decreasing rate is limited at the degree of opening TVO1 or below of an electronically controlled throttle valve, and thereby a steep change in torque due to a quick change of the degree of throttle opening is relieved. This enables reducing the fuel consumption by maintaining the fuel cut to the engine. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for a vehicle equipped with an automatic transmission having a lock-up clutch.
[0002]
[Prior art]
In an automatic transmission for a vehicle having a torque converter disposed between the engine and the vehicle, a lock-up clutch is provided in the torque converter, and the lock-up clutch is engaged in a high vehicle speed region in order to reduce fuel consumption. I have.
Further, even in a low vehicle speed range, by engaging the lock-up clutch, it is possible to cut off the fuel supply to the engine (fuel cut) while driving the engine from the wheel side to prevent the engine from stopping. Attempts have been made to reduce consumption.
[0003]
When the lock-up clutch is engaged in this low vehicle speed range, a step in the driving force generated at the time of engagement becomes a shock. Therefore, in order to reduce the shock, the operating pressure of the lock-up clutch, that is, the lock-up difference in the automatic transmission control, is reduced. A so-called smooth lock-up control in which the pressure command value is gradually increased is employed.
[0004]
[Problems to be solved by the invention]
However, when the driver releases his / her foot from the accelerator pedal during the smooth lockup control (foot return), the throttle opening is fully closed, and the driving force from the engine suddenly changes from positive torque to negative torque. Therefore, if the lock-up clutch remains engaged while the lock-up differential pressure command value is higher than the predetermined value, a shock occurs.
[0005]
In order to prevent this phenomenon, as shown in FIG. 6, when the foot is returned during the smooth lock-up control, the lock-up is released. However, this makes it impossible to maintain the fuel cut of the engine. However, the goal of reducing fuel consumption cannot be achieved.
Further, there is a problem in that the frequency of engagement and disengagement of the lock-up clutch increases, thereby affecting the friction surface and other durability of the lock-up clutch.
[0006]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a control apparatus for a vehicle that does not give a passenger an uncomfortable feeling due to a shock while improving fuel consumption performance in view of the above problems.
[0007]
[Means for Solving the Problems]
Therefore, according to the present invention, in a vehicle equipped with an automatic transmission equipped with an engine and having a lock-up clutch, when the accelerator pedal for engine control is returned, the engine is switched from the engine to the automatic transmission. And a sudden change in drive torque.
[0008]
The invention according to claim 2 further includes a lock-up clutch control means for maintaining the lock-up on state when the lock-up clutch is in a predetermined lock-up on state at the time of returning the foot.
[0009]
According to a third aspect of the present invention, the engine is provided with an electronically controlled throttle valve, and the drive torque sudden change mitigation means limits the rate of decrease of the opening of the electronically controlled throttle valve, thereby mitigating a sudden change in drive torque. It is.
According to a fourth aspect of the present invention, the drive torque sudden change reducing means limits the decrease rate after the opening of the electronically controlled throttle valve becomes equal to or less than a predetermined reference value.
[0010]
According to a fifth aspect of the present invention, when the predetermined lock-up ON state is a smooth lock-up ON state, and the lock-up clutch control means is in the smooth lock-up ON state, the lock to the lock-up solenoid for operating the lock-up clutch is controlled. The lock-up ON state is maintained by increasing the up differential pressure command value until it reaches a predetermined set value.
[0011]
The lock-up clutch control means increases the lock-up differential pressure command value when the lock-up differential pressure command value is larger than a predetermined reference value.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a diagram showing an embodiment.
The automatic transmission 5 is connected to the engine 1 via a torque converter 6 having a lock-up clutch 9.
The engine 1 is controlled by an engine control unit 4. The engine 1 includes an electronically controlled throttle valve 10 controlled by an engine control unit 4 based on an operation of an accelerator pedal 2.
[0013]
The engine control unit 4 controls the opening of the throttle valve 10 in accordance with the amount of depression of the accelerator pedal 2, and also, based on the opening (throttle opening) TVO of the throttle valve 10 and the current engine speed. And controls the fuel injection amount and the ignition timing.
The engine control unit 4 also sends a signal of the throttle opening TVO to a later-described transmission control unit 20 via the in-vehicle network L.
[0014]
The automatic transmission 5 is controlled by a transmission control unit 20.
A vehicle speed sensor 15 is attached to the output shaft 8 of the automatic transmission 5, and a signal corresponding to the vehicle speed is input to the transmission control unit 20. The transmission control unit 20 obtains the vehicle speed Vsp by converting the output shaft speed.
The transmission control unit 20 is connected to an accelerator pedal sensor 3 for detecting a state in which the accelerator pedal 2 is released by returning the foot.
[0015]
The transmission control unit 20 determines the traveling state based on the throttle opening TVO obtained via the in-vehicle network L and the vehicle speed Vsp obtained from the vehicle speed sensor 15, and automatically determines a transmission ratio corresponding to the traveling state. A control signal is output to the transmission 5. This control signal includes a control signal to the lock-up solenoid 9a of the control valve 7 of the automatic transmission 5.
[0016]
In the present embodiment, the control area at the time of returning the foot shown in FIG. 2 is a main control target.
That is, when the foot is returned from the accelerator pedal 2 during the smooth lock-up control (SM L / U ON), the lock-up differential pressure command value LUS to the lock-up solenoid 9a becomes equal to the predetermined reference value LUS0. When it is larger, the lock-up ON is assured by raising the lock-up differential pressure command value until a predetermined higher set value LUS1 is reached as the return control.
Further, at the time of returning the foot, the trigger signal Q is output to the engine control unit 4 via the in-vehicle network L to limit the decrease rate of the throttle opening, thereby alleviating a sudden change in torque due to a sudden change in the throttle opening.
[0017]
On the other hand, even if the lock-up clutch 9 is in a smooth lock-up, the normal control state is continued unless the foot is returned.
If the state is other than the smooth lockup, the normal control state is continued regardless of whether the foot is in the return state.
[0018]
FIG. 3 is a flowchart showing a control flow in the transmission control unit 20 during the smooth lockup.
In step 100, the transmission control unit 20 first checks whether the smooth lockup control is being performed (ON) in the low vehicle speed range.
When the smooth lock-up control is being performed, it is checked in step 101 whether or not the vehicle is in the foot-return state based on a signal from the accelerator pedal sensor 3.
When it is in the foot return state, the process proceeds to step 102. If the smooth lock-up control is not being performed in the check in step 100, or if the vehicle is not in the returning state in the check in step 101, the process returns to step 100.
[0019]
In step 102, a trigger signal Q for engine control is output to the engine control unit 4 via the in-vehicle network L.
Then, in step 103, it is checked whether the lock-up differential pressure command value LUS is larger than the reference value LUS0. If the lock-up differential pressure command value is larger than the reference value LUS0, the process proceeds to step 104; Proceed to step 107.
[0020]
In step 104, the lock-up differential pressure command value LUS is increased by a predetermined unit amount ΔLUS, and in the next step 105, this increased new lock-up differential pressure command value LUS is output to continue the smooth lock-up control. I do.
Thereafter, in step 106, it is checked whether or not the new lock-up differential pressure command value LUS has reached a predetermined set value LUS1.
[0021]
Steps 104 and 105 are repeated until the lock-up differential pressure command value LUS reaches the set value LUS1 to end one flow.
This prevents the automatic transmission from shifting to lock-up release due to lack of lock-up capacity during smooth lock-up in response to engine torque change due to foot release.
FIG. 5A shows a change in the lockup differential pressure command value due to the above control.
Steps 103 to 106 described above constitute the lock-up clutch control means in the present invention.
[0022]
On the other hand, in step 107 when the lockup differential pressure command value LUS is equal to or less than the reference value LUS0, a smooth off control for gradually releasing (off) the lockup clutch is performed. This is because if the reference value LUS0 or less, the required lock-up capacity cannot actually be met by increasing the unit amount ΔLUS.
[0023]
Next, FIG. 4 is a flowchart showing a flow of control of the electronic control throttle valve 10 in the engine control unit 4 at the time of returning the foot.
First, in step 201, it is checked whether or not a trigger signal Q indicating the time of returning the foot is input from the transmission control unit 20.
If the trigger signal Q has been input, in step 202, the throttle opening command value under control is checked in accordance with the depression amount of the accelerator pedal 2, and when the throttle opening TVO becomes equal to or less than the predetermined reference value TVO1, Check if it is.
[0024]
Here, if the throttle opening TVO is equal to or less than TVO1, the routine proceeds to step 203, where the throttle opening command value is set to TVO = TVO-ΔTVO using the preset reduction ΔTVO.
And returns to step 201.
Thus, while the trigger signal Q is being input, the throttle opening command value decreases only by ΔTVO below the throttle opening TVO1 and the rate of decrease is limited.
It should be noted that if the trigger signal Q is not input in the check in step 201, and if the throttle opening is larger than the reference value TVO1 in the check in step 202, the process returns to step 201 again.
FIG. 5B shows a change in the throttle opening command value due to the above control. Steps 202 and 203 of the above flow constitute drive torque sudden change reduction means in the present invention.
[0025]
The embodiment is configured as described above. When the foot is released from the accelerator pedal 2 during the smooth lock-up control in the low vehicle speed range, the transmission control unit 20 sets the lock-up differential pressure command value LUS to the reference value. When the value is larger than LUS0, the lockup differential pressure command value is increased until the set value LUS1 becomes higher, thereby preventing the shift to the lockup release due to the shortage of the lockup capacity. The frequency of engagement and disengagement of the up-clutch 9 can be reduced to improve durability, and the fuel cut can be maintained in the engine 1, so that the fuel consumption can be surely reduced.
[0026]
In addition, since the engine control unit 4 limits the rate of decrease when the throttle opening is equal to or less than the reference value TVO1, a sudden change in torque due to a sudden change in the accelerator pedal 2 foot return is prevented, and the limitation of the rate of decrease is limited to the reference value TVO1. Since it starts after lowering, there is no feeling of idle running due to response delay.
[0027]
【The invention's effect】
As described above, the present invention has the drive torque sudden change mitigation means for alleviating the sudden change in the drive torque from the engine to the automatic transmission when the accelerator pedal is released, so that, for example, lock-up at low vehicle speed Even when the fuel consumption is reduced by turning on the fuel, a shock due to a sudden change in torque is prevented.
[0028]
Further, when the state of the lock-up clutch is a predetermined lock-up ON state such as a smooth lock-up ON, the lock-up clutch has a lock-up clutch control means for holding the lock-up ON state. The shift to lock-up off due to insufficient capacity of the battery is prevented. As a result, for example, the fuel cut for reducing fuel consumption can be reliably maintained, and the frequency of lock-up ON / OFF is reduced, thereby improving the durability of the lock-up clutch.
[0029]
The sudden change in drive torque can be easily reduced by limiting the rate of decrease in the opening of the electronically controlled throttle valve.
At this time, the reduction rate is limited after the opening of the throttle valve is equal to or less than the predetermined reference value, thereby alleviating a sudden change in torque, not causing a delay in response to returning to the foot, and providing an idling feeling. Absent.
[0030]
Also, the lock-up clutch control means can easily maintain the lock-up ON state by increasing the lock-up differential pressure command value to a predetermined set value in the smooth lock-up ON state.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the present invention.
FIG. 2 is a diagram showing a control area in the embodiment.
FIG. 3 is a flowchart showing a control flow in a transmission control unit.
FIG. 4 is a flowchart showing a flow of control of an electronic control throttle valve in the engine control unit.
FIG. 5 is a diagram showing changes in a lockup differential pressure command value and a throttle opening.
FIG. 6 is a diagram showing an operation of a conventional lock-up control.
[Explanation of symbols]
Reference Signs List 1 engine 2 accelerator pedal 3 accelerator pedal sensor 4 engine control unit 5 automatic transmission 6 torque converter 7 control valve 8 output shaft 9 lock-up clutch 9a lock-up solenoid 10 electronic control throttle valve 15 vehicle speed sensor 20 transmission control unit L in the vehicle network

Claims (6)

In a vehicle equipped with an automatic transmission equipped with an engine and a lock-up clutch,
A control device for a vehicle, comprising: a drive torque sudden change reducing unit configured to reduce a sudden change in drive torque from an engine to an automatic transmission when an accelerator pedal for engine control is released. In a vehicle equipped with an automatic transmission equipped with an engine and a lock-up clutch,
A drive torque sudden change reducing means for reducing a sudden change in drive torque from the engine to the automatic transmission when the accelerator pedal for engine control is returned,
A control device for a vehicle, comprising: a lock-up clutch control unit that holds the lock-up on state when the lock-up clutch is in a predetermined lock-up on state when the foot is returned. The engine has an electronically controlled throttle valve,
3. The vehicle control device according to claim 1, wherein the drive torque sudden change alleviating means reduces a sudden change in drive torque by limiting a rate of decrease in an opening degree of the electronically controlled throttle valve. 4. The control device for a vehicle according to claim 3, wherein the drive torque sudden change reducing unit limits the decrease rate after the opening of the electronically controlled throttle valve becomes equal to or less than a predetermined reference value. The predetermined lock-up on state is a smooth lock-up on state,
The lock-up clutch control unit increases the lock-up differential pressure command value to the lock-up solenoid for operating the lock-up clutch until a predetermined set value is reached when the lock-up clutch is in the smooth lock-up ON state, thereby performing lock-up. The vehicle control device according to any one of claims 2 to 4, wherein the on-state is maintained. 6. The vehicle control device according to claim 5, wherein the lock-up clutch control means increases the lock-up differential pressure command value when the lock-up differential pressure command value is larger than a predetermined reference value.

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