JP7647633B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device.

When a vehicle accelerates by depressing the accelerator from an off-accelerator state, for example, backlash is eliminated in the power transmission system of the vehicle. In other words, when the vehicle transitions from a driven state to a driving state, the input direction of the torque in the power transmission system changes, eliminating backlash that has occurred in the engagement parts and fitting parts included in the power transmission system. Conventionally, there is known a vehicle control device that determines whether the vehicle is in a driven state, and when it is determined that the vehicle is in a driven state, performs torque control to reduce the impact associated with backlash elimination (see, for example, Patent Document 1). Whether the vehicle is in a driven state is determined by comparing an estimated value of the drive torque in the vehicle with a preset driven state determination value.

JP 2020-197138 A

Vehicles are equipped with auxiliary equipment such as an air conditioner and an alternator. The auxiliary equipment is driven by a drive source included in the drive transmission system. For this reason, the operation of the auxiliary equipment affects the drive torque of the vehicle. However, the vehicle control device disclosed in Patent Document 1 does not take the auxiliary equipment into consideration, and it is anticipated that there may be cases where the shock caused by the backlash is not sufficiently mitigated.

Therefore, the vehicle control device disclosed in this specification aims to reduce the impact caused by the backlash, regardless of the state of the auxiliary equipment equipped on the vehicle.

The above objective can be achieved by a vehicle control device including: a drive torque estimation value acquisition unit that acquires a drive torque estimation value, which is an estimate of the drive torque input to the power transmission device of the vehicle; a drive judgment value setting unit that sets a drive judgment value for determining whether the vehicle is in a driven state or not to a value higher than the drive judgment value when the accessories are in a non-operating state when the operating state of the accessories equipped in the vehicle affects the drive torque estimation value; and a torque increase rate suppression control unit that suppresses the increase rate of the torque generated by the drive source of the vehicle when the drive torque estimation value is lower than the drive judgment value set by the drive judgment value setting unit.

The present invention can reduce the impact caused by removing rattle, regardless of the state of the vehicle's auxiliary equipment.

FIG. 1 is a schematic diagram of a vehicle equipped with a vehicle control device (ECU) according to an embodiment. FIG. 2 is a flowchart showing an example of the torque increase rate suppression control executed by the ECU according to the embodiment. FIG. 3 is a time chart showing an example of the transition of each value during torque increase rate suppression control by the ECU according to the embodiment. FIG. 4 is an example of a map for acquiring the engine torque. FIG. 5 is a diagram showing an example of the relationship between the driven determination value, the driving torque estimate value, and the actual driving torque value when the air conditioner is ON/OFF. FIG. 6 is a diagram showing an example of setting the driven determination value based on the output of the air conditioner.

Below, an embodiment of the present invention will be described with reference to the attached drawings. However, the dimensions, ratios, etc. of each part in the drawings may not be illustrated to be exactly the same as the actual ones. Also, some details may be omitted in some drawings. Furthermore, the scale of each element depicted in each drawing may differ.

[General configuration of the vehicle]
1 is a schematic diagram of a vehicle 1. The vehicle 1 includes a power transmission system in which an engine 10, a power transmission device 20, and drive wheels 30 are arranged in this order. The vehicle 1 also includes an air conditioner (hereinafter simply referred to as "air conditioner") 40 as an auxiliary device, and an ECU (Electronic Control Unit) that functions as a vehicle control device.

The engine 10 is an internal combustion engine and is the driving source for propelling the vehicle 1. The engine 10 is, for example, a gasoline engine that uses gasoline as fuel or a diesel engine that uses diesel as fuel. The driving source for propelling the vehicle 1 is not limited to an engine, but may be a motor, or may be a combination of an engine and a motor.

The power transmission device 20 transmits the output of the engine 10, i.e., the driving torque, to the driving wheels 30. The power transmission device 20 includes a transmission, a differential, and a drive shaft. The transmission may be a manual transmission or an automatic transmission including a torque converter. The transmission may be a CVT (Continuously Variable Transmission), or may have a conventionally known configuration such as a DCT (Dual Clutch Transmission). The power transmission device 20 may include a transfer and a propeller shaft. Furthermore, if the vehicle 1 is a hybrid vehicle equipped with an engine and a motor as driving sources, the power transmission device includes a disconnecting mechanism between the engine and the motor.

The drive wheels 30 transmit the drive torque of the engine 10, which is transmitted from the power transmission device 20, to the road surface, and the resulting frictional force causes the vehicle 1 to move. The drive wheels 30 may be the left and right front wheels, the left and right rear wheels, or both.

While the vehicle 1 is traveling, the power transmission device 20 switches between a driving state and a driven state depending on the generation state of the driving torque from the engine 10. In the driving state, the driving torque generated by the engine 10 is transmitted toward the downstream side of the power transmission device 20 in the power transmission direction, and the driving wheels 30 are driven. On the other hand, in the driven state, the driving torque from the engine 10 is reduced, and the rotation resistance of the driving wheels 30 is transmitted to the engine 10 side. In the driven state, the power transmission device 20 is in a state where the gears included in the transmission and the engagement parts and fitting parts included in the differential and drive shaft are loosened, causing backlash (backlash). When the vehicle 1 transitions from the driven state to the driving state, this backlash is eliminated. In this embodiment, the torque rise rate suppression control is executed to suppress the torque rise rate of the engine 10 when this backlash is eliminated, thereby mitigating the impact when the backlash is eliminated. The torque rise rate suppression control will be described later.

The ECU 100 is an electronic control unit that performs various control processes related to the vehicle 1. The ECU 100 is mainly composed of a computer including, for example, a CPU (Central Processing Unit), a memory device such as a RAM (Random Access Memory), an auxiliary storage device such as a ROM (Read Only Memory), and an interface device for input and output. The ECU 100 realizes various control processes related to the vehicle 1 by executing, on the CPU, a program installed in the auxiliary storage device.

The air conditioner 40 is an air conditioning device that conditions the air inside the vehicle 1. The air conditioner 40 includes a compressor and a blower fan that are driven by the engine 10. Therefore, when the air conditioner 40 is operating, it may affect the drive torque transmitted to the power transmission device 20, and the degree of this effect varies depending on the operating status of the air conditioner 40.

The ECU 100 is electrically connected to an engine speed sensor 51, an air flow meter 52, an air-fuel ratio sensor 53, an accelerator opening sensor 54, a throttle opening sensor 55, and an input shaft speed sensor 56.

The engine speed sensor 51 detects the rotation speed of the engine 10 (hereinafter referred to as "engine speed"). The engine speed sensor 51 is, for example, a crank sensor or a cam sensor. The output (detection result) of the engine speed sensor 51 is input to the ECU 100. This allows the ECU 100 to obtain the engine speed.

The air flow meter 52 detects the amount of intake air drawn into the cylinders of the engine 10. The output (detection result) of the air flow meter 52 is input to the ECU 100. This allows the ECU 100 to obtain the amount of intake air.

The air-fuel ratio sensor 53 detects the air-fuel ratio of the exhaust gas from the engine 10. The output (detection result) of the air-fuel ratio sensor 53 is input to the ECU 100. This allows the ECU 100 to obtain the air-fuel ratio.

The accelerator opening sensor 54 detects the opening of an accelerator pedal (not shown), i.e., the degree to which the accelerator pedal is depressed (hereinafter referred to as "accelerator opening"). The output (detection result) of the accelerator opening sensor 54 is input to the ECU 100. This allows the ECU 100 to obtain the accelerator opening.

The throttle opening sensor 55 detects the opening of a throttle valve (not shown) provided in the engine 10.

The input shaft speed sensor 56 detects the rotation speed of the input shaft of the transmission included in the power transmission device 20.

In addition, various other sensors are electrically connected to the ECU 100, and various detection results are input, but their description will be omitted here.

The ECU 100 includes a driven state determination value setting unit 101, a driving torque estimation value acquisition unit 102, a driven state determination unit 103, and a torque increase rate suppression control unit 104.

The driven determination value setting unit 101 sets a driven determination value, which is a threshold value for determining whether the vehicle 1 is in a driven state or not, depending on the operating status of the air conditioner 40. Referring to FIG. 3, the driven determination value setting unit 101 sets the driven determination threshold value when the air conditioner 40 is in the ON state to a value higher than the driven determination value when the air conditioner 40 is in the OFF state. This point will be described in detail later.

The drive torque estimation value acquisition unit 102 estimates the value of the drive torque output by the engine 10 and input to the power transmission device 20.

The driven state determination unit 103 compares the driven state determination value set by the driven state determination value setting unit 101 with the drive torque estimation value estimated by the drive torque estimation value acquisition unit 102. Then, based on the comparison result, the driven state determination unit 103 determines whether the vehicle 1 is in a driven state.

The torque increase rate suppression control unit 104 executes control to suppress the increase rate of the torque generated by the drive source of the vehicle 1 when the drive torque estimate value is lower than the driven judgment value, that is, when it is judged that the vehicle is in a driven state.

[Torque increase rate suppression control]
Next, the torque increase rate suppression control in the vehicle 1 will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a flowchart showing an example of the torque increase rate suppression control executed by the ECU 100. Fig. 3 is a time chart showing an example of the transition of each value during the torque increase rate suppression control by the ECU 100. The ECU 100 repeatedly executes the control based on the flowchart shown in Fig. 2 from the end of the initial process when the ignition of the vehicle 1 is turned on to the start of the termination process when the ignition of the vehicle 1 is turned off.

First, in step S1, the driving torque estimation value acquisition unit 102 acquires a driving torque estimation value. The driving torque estimation value is acquired based on the engine torque calculated from the engine speed acquired by the engine speed sensor 51 and the throttle opening acquired by the throttle opening sensor 55. For example, as shown in FIG. 4, the engine torque is calculated based on a map (engine torque map) showing a predetermined relationship between the engine torque, the engine speed, and the throttle opening. The driving torque estimation value acquisition unit 102 acquires a driving torque estimation value taking into consideration factors that affect the engine torque acquired based on the map shown in FIG. 4. Here, the factors that affect the engine torque include the ignition timing in the engine 10, the auxiliary load torque, the torque loss of each part of the engine, and the air-fuel ratio acquired by the air-fuel ratio sensor 53. Values for evaluating these factors are acquired in advance by the ECU 100 prior to acquiring the driving torque estimation value, and the engine torque is corrected by these values to obtain the driving torque estimation value. The torque loss of each part of the engine includes friction torque and pumping loss torque in each part of the engine. These torque losses can be obtained in advance through experiments and simulations using an actual vehicle. With reference to FIG. 3, the drive torque estimate changes in accordance with changes in the accelerator opening. In other words, the change in the drive torque estimate roughly coincides with the change in the accelerator opening. For example, when the accelerator opening increases at time t1 shown in FIG. 3, the drive torque estimate also increases accordingly.

In step S2, which is executed following step S1, the driven judgment value setting unit 101 determines whether the air conditioner 40 is operating. If the driven judgment value setting unit 101 makes a positive determination (Yes determination) in step S2, the process proceeds to step S3, and if the driven judgment value setting unit 101 makes a negative determination (No determination) in step S2, the process proceeds to step S4. In step S3, the driven judgment value setting unit 101 selects a driven judgment value when the air conditioner 40 is operating (ON), and in step S4, selects a driven judgment value when the air conditioner 40 is stopped (not operating) (OFF).

In the example shown in FIG. 3, the air conditioner 40 starts operating at time t2. Therefore, the driven judgment value setting unit 101 selects the driven judgment value when the air conditioner 40 is stopped (non-operating state) at a timing before time t2. Then, the driven judgment value is switched at time t2, and the driven judgment value when the air conditioner 40 is operating is selected at a timing after time t2. Here, the driven judgment value when the air conditioner 40 is operating is a higher value than the driven judgment value when the air conditioner 40 is in a non-operating state. The driven judgment value is compared with the driving torque estimation value in step S5, which will be described in detail later, and when the air conditioner 40 is operating, its operating state affects the driving torque estimation value. In other words, it is assumed that the estimation accuracy of the driving torque estimation value decreases when the air conditioner 40 is operating. Therefore, when the air conditioner 40 is operating and its operating state affects the torque estimation value, the driven judgment value is set to a higher value than when the air conditioner 40 is in a non-operating state. This point will be described in detail later.

The driven judgment value setting unit 101 then proceeds to step S5, whether or not it has gone through step S3 or step S4. In step S5, the driven state judgment unit 103 judges whether the vehicle 1 is in a state in which it is accelerating from the driven state. In the example shown in FIG. 3, the accelerator opening decreases at time t3, and the driving torque estimate value decreases accordingly. Then, the driving torque estimate value is generally below the driven judgment value at time t4. In this way, when the driving torque estimate value falls below the driven judgment value, it is judged that the vehicle 1 is in a driven state. Then, when the accelerator opening increases at time t5, the driving torque estimate value also increases accordingly, and transitions to a state in which it exceeds the driven judgment value. When the accelerator opening starts to increase, it is judged that the vehicle 1 is in an accelerating state. In the example shown in FIG. 3, the accelerator opening starts to increase at time t5, and the driven state judgment unit 103 judges that the vehicle 1 is in a driven state at time t5. That is, a positive determination is made in step S5. Note that in this embodiment, since the drive torque estimate value is below the driven determination value at approximately time t4, it may be determined that the vehicle 1 is in a driven state at this timing.

Here, referring to FIG. 5, the accuracy of the driven determination of the vehicle 1 will be described. The vehicle 1 is determined to be driven when the driving torque estimated value falls below the driven determination value. When the air conditioner 40 is operating in the vehicle 1, the operating status of the air conditioner 40 may affect the driving torque estimated value, so that the deviation between the driving torque estimated value and the actual driving torque value may become large. As illustrated in FIG. 5, a case is assumed in which the driving torque estimated value is larger than the actual driving torque value. In such a case, although the actual driving torque value is lower than the driven determination value when the air conditioner 40 is in a non-operating state, the driving torque estimated value exceeds the driven determination value when the air conditioner 40 is in a non-operating state. For this reason, the vehicle 1 is determined to be in a driving state, and is not determined to be in a driven state. As a result, even though the vehicle is in a state in which backlash is actually eliminated, the torque rise rate suppression control described later is not executed, and the impact at the time of backlash elimination cannot be mitigated. In contrast, by setting the driven determination value to a value higher than the value when the air conditioner 40 is in a non-operating state, the vehicle is determined to be driven even when the driving torque estimated value is estimated to be higher than the actual driving torque value. As a result, torque increase rate suppression control is implemented, mitigating the impact caused by the backlash.

If the ECU 100 judges in step S5 as positive, it proceeds to step S6, and if the ECU 100 judges in step S5 as negative, it proceeds to step S7. In step S6, the torque increase rate suppression control unit 104 executes torque increase rate suppression control. The torque increase rate suppression control extends the time until the target drive torque (engine torque) is reached, and slows down the rate at which the drive torque increases, compared to when such control is not executed. This allows the backlash to be gradually eliminated, and the shock at that time is mitigated. By mitigating this shock, the generation of abnormal noise during backlash is also suppressed. On the other hand, in the engine torque control in step S7, the torque increase rate is made to reach the target drive torque at a higher torque increase rate than the torque increase rate in the torque increase rate suppression control executed in step S6. This improves the responsiveness of the vehicle speed to the accelerator operation, and ensures a good acceleration feeling of the vehicle 1. In addition, in the engine torque control in step S7, the torque increase rate may also be changed according to the accelerator opening acquired by the accelerator opening sensor 54. After step S7 is completed, the process ends.

In step S8, which is executed following step S6, the torque increase rate suppression control unit 104 determines whether the condition for canceling the torque increase rate suppression control is satisfied. In the example shown in FIG. 3, the condition for canceling the torque increase rate suppression control is satisfied at time t7. The condition for canceling the torque increase rate suppression control can be set as appropriate. In this embodiment, it is determined that the condition for cancellation is satisfied when the amount of change in the input shaft rotation speed detected by the input shaft rotation speed sensor 56 becomes larger than a preset threshold value. Specifically, if the amount of change in the transmission rotation speed within the most recent specified period is larger than the threshold value, it is determined that the rotation speed of the transmission has changed in the forward rotation direction and transitioned to a driving state, and it is determined that the cancellation condition is satisfied. Note that the threshold value in this case is preset as a value (lower limit value) that can be determined that the rotation speed of the entire power transmission mechanism of the transmission has changed in the forward rotation direction, for example, through experiments on an actual vehicle or computer simulation.

Other conditions for canceling the torque increase rate suppression control include the following conditions. For example, the fluctuation range of the accelerator opening is within a certain range for a predetermined period after the acceleration determination, and the fluctuation range of the drive torque estimate is within a certain range for a predetermined period after the drive torque estimate increases. In the example shown in FIG. 3, the accelerator opening and drive torque estimate are almost constant for a predetermined period after time t6, and it is determined that the cancellation condition is satisfied. These cancellation conditions can be adopted alone or in combination with multiple conditions as appropriate.

If the torque increase rate suppression control unit 104 judges in step S8 as positive, it proceeds to step S9. On the other hand, if the torque increase rate suppression control unit 104 judges in step S8 as negative, it repeats the process until the torque increase rate suppression control unit 104 judges in step S9 as positive, and ends the series of processes.

[Modification]
In the above embodiment, the driven judgment value is set depending on whether the air conditioner 40 is in an operating state or not, but the driven judgment value may be set further taking into consideration the output of the air conditioner 40. For example, as shown in FIG. 6, the greater the output of the air conditioner 40, the greater the driven judgment value may be. When a higher driven judgment is selected, the more likely it is that the driven judgment will be made, and the more likely it is that the torque rise rate suppression control will be executed. This makes it possible to mitigate the impact when backlash is eliminated. In addition, because the opportunities for executing the torque rise rate suppression control are finely set, it becomes easier to both mitigate the impact when backlash is eliminated and maintain the acceleration feeling of the vehicle 1.

[effect]
In the above embodiment, when the air conditioner 40 is operating and the driving torque estimated value is affected, the driven determination value is set to a value higher than the value when the air conditioner 40 is being driven. This makes it possible to execute the torque increase rate suppression control even when the air conditioner 40 is operating and the driving torque estimated value is likely to deviate from the actual driving torque value. This makes it possible to reduce the impact caused when the backlash is eliminated.

In the above embodiment, control based on the operating status of the air conditioner 40 as an auxiliary device has been described, but control based on the operating status of an alternator included in the auxiliary devices may also be performed. The operating status of the alternator can be incorporated into the control in a similar manner to that of the air conditioner 40. In addition, the auxiliary devices are not limited to the air conditioner 40 and the alternator, and include devices whose operation may affect the drive torque estimate value. In other words, devices that are operated by a drive source for running the vehicle 1 and that affect the drive torque transmitted to the power transmission device 20 are included in the auxiliary devices.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims.

REFERENCE SIGNS LIST 1 vehicle 10 engine 20 power transmission device 30 drive wheels 40 air conditioner 51 engine speed sensor 52 air flow meter 53 air-fuel ratio sensor 54 accelerator opening sensor 55 throttle opening sensor 56 input shaft speed sensor 100 ECU (vehicle control device)
101 Driven state determination value setting unit 102 Drive torque estimated value acquisition unit 103 Driven state determination unit 104 Torque increase rate suppression control unit

Claims (1)

a drive torque estimated value acquisition unit that acquires a drive torque estimated value that is an estimate of a drive torque input to a power transmission device of a vehicle;
a driven determination value setting unit that sets a driven determination value for determining whether or not the vehicle is in a driven state, when an operating state of an auxiliary device provided in the vehicle affects the drive torque estimation value, to a value higher than the driven determination value when the auxiliary device is in a non-operating state;
a torque increase rate suppression control unit that suppresses an increase rate of torque generated by a drive source of the vehicle when the drive torque estimated value is lower than the driven determination value set by the driven determination value setting unit;
A vehicle control device comprising:

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