JP3937124B2 - Vehicle motor torque control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor torque control device that controls a motor mounted as a power source in a vehicle.
[0002]
[Related background]
In general, an electric vehicle or a hybrid vehicle can arbitrarily stop a motor that is a drive source. For example, a so-called creep phenomenon such as a vehicle having an internal combustion engine with an automatic transmission, that is, torque via a torque converter when the vehicle is stopped, etc. The phenomenon in which the vehicle moves slightly forward by transmission basically does not occur. However, this creep phenomenon has advantages such as being able to easily advance the vehicle at a slow speed in a traffic jam, or preventing the vehicle from moving backward from the brake to the accelerator when starting on an uphill road. In the present situation where vehicles that cause such a creep phenomenon are widespread, there is a possibility that the user may feel uncomfortable if the creep phenomenon does not occur. Therefore, in order to answer such a demand, a vehicle has been proposed in which a minute torque is applied to the motor even when the accelerator is off to generate a creep phenomenon.
[0003]
However, in a state where the creep phenomenon is suppressed by a brake operation, for example, when waiting for a signal, the driver is forced to use the brake operation unnecessarily and power is consumed unnecessarily. Rather, it is directly linked to disadvantages. Therefore, for example, in the electric vehicle described in JP-A-11-8912, creep torque is generated only when the brake is not operated.
[0004]
[Problems to be solved by the invention]
However, in the electric vehicle described in the publication, since the creep torque is uniquely set to 0 at the time of brake operation, it cannot be said that the control is always according to the driving state. For example, if the brake operation is stopped to start from waiting for a signal, the creep torque is suddenly started and the vehicle is suddenly started, giving the driver a sense of incongruity. In addition, when the distance from the preceding vehicle is adjusted by braking while moving forward at a slow speed due to traffic jams, etc., creep torque is generated intermittently depending on the presence or absence of the brake operation, and in addition, smooth distance adjustment cannot be performed. Like the above, it causes a sense of incongruity.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle motor torque control device that can generate an appropriate creep torque according to a brake operation and realize a smooth operation without a sense of incongruity.
[0006]
[Means for Solving the Problems]
To achieve the above object, according to the present invention, in a motor torque control device for a vehicle having a motor as a power source, vehicle speed detecting means for detecting the vehicle speed, road gradient detecting means for detecting the road gradient, and braking force of the vehicle Braking force detection means for detecting the vehicle speed, and creep torque calculation means for calculating the creep torque to be generated on the drive wheels of the vehicle based on the vehicle speed detected by the vehicle speed detection means and the road gradient detected by the road gradient detection means And, based on the braking force detected by the braking force detecting means, a braking torque calculating means for calculating a braking side torque acting on the drive wheel by a brake operation, and when the driver's accelerator operation is not performed, Subtract the braking torque calculated by the braking torque calculation means from the creep torque calculated by the creep torque calculation means. And a motor torque control means for controlling the motor based on Riputoruku.
[0007]
Accordingly, the creep torque to be generated on the driving wheel is calculated based on the vehicle speed and the road gradient, and the braking side torque acting on the driving wheel is calculated based on the braking force, and the creep after subtracting the braking side torque is calculated. The motor is controlled based on the torque. As a result, for example, creep torque is generated below a predetermined vehicle speed that requires a creep phenomenon, or the creep torque is increased as the slope of the uphill road becomes steep. Will be reduced. As a result, the necessary minimum creep torque is set by subtracting the useless torque consumed by the brake operation, the power consumption of the motor is reduced, and the braking force required to stop and hold the vehicle is reduced. The driver's labor is reduced.
[0008]
And since the creep torque is corrected steplessly according to the braking force in this way, the creep torque consistent with the driving state is always realized. For example, when the brake operation is stopped to start from the signal wait, When the creep torque is gradually raised as the force decreases, the vehicle can start smoothly, and when the distance from the preceding vehicle is adjusted by the brake while moving forward at a slow speed in a traffic jam, The creep torque gradually increases / decreases according to the braking force, and the distance can be adjusted smoothly.
Moreover, the net creep torque applied to motor control is calculated by subtracting the braking torque based on the braking force from the original creep torque that should be generated on the drive wheels due to the creep phenomenon. Since the calculation process is executed according to the procedure in accordance with the torque generation situation at the time, it is possible to accurately control the creep torque reflecting the braking force.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is embodied in a motor torque control device for a hybrid vehicle will be described.
FIG. 1 is an overall configuration diagram showing a torque control device for a hybrid vehicle of this embodiment. As shown in this figure, the hybrid vehicle of this embodiment includes an engine 1 side and a motor 2 side including a drive system. The front wheels 3 a are driven by the engine 1, and the rear wheels 3 b are driven by the motor 2. More specifically, an automatic transmission 5 is connected to the gasoline engine 1 mounted on the front side of the vehicle via a clutch 4, and the rotation of the engine 1 is moved to the front wheel 3 a side via the automatic transmission 5 and the differential 6. Communicated. The basic configuration of the automatic transmission 5 is the same as that of a general mechanical transmission that performs manual shift operation. However, as described later, the shift operation, the clutch operation, and the throttle operation of the engine 1 are automated. The automatic transmission is configured to be possible.
[0010]
A planetary gear type speed reducer 7 is connected to the motor 2 mounted on the rear side of the vehicle, and the rotation of the motor 2 is transmitted to the rear wheel 3b side as a drive wheel through the speed reducer 7 and the differential 8. Is done. A traveling battery 10 is connected to the motor 2 via an inverter 9, and the rotation of the motor 2 is controlled by the inverter 9.
On the other hand, an input / output device (not shown), a storage device (ROM, RAM, etc.) used for storage of a control program, a control map, a central processing unit (CPU), a timer counter, etc. Control unit) is installed. On the input side of the ECU 11, there are an accelerator sensor 12 for detecting the accelerator operation amount APS by the driver, a throttle sensor 13 for detecting the throttle opening TPS of the engine 1, and a rotational speed Nc on the output side (transmission side) of the clutch 4. A clutch rotation speed sensor 14 to detect (in place of this sensor 14, the clutch rotation speed Nc may be estimated from the vehicle speed V), a brake hydraulic pressure sensor 15 as a brake force detection means for detecting a brake hydraulic pressure Pbk, Various sensors such as a vehicle speed sensor 16 as vehicle speed detecting means for detecting the vehicle speed V are connected. Further, on the output side of the ECU 11, a shift actuator 17 that performs a shift operation of the automatic transmission 5, a clutch actuator 18 that performs a connection / disconnection operation of the clutch 2, a throttle actuator 19 that opens and closes a throttle valve of the engine 1, And the inverter 9 and the like are connected.
[0011]
In the hybrid vehicle of this embodiment, the start is basically performed by the motor 2, and the subsequent travel is performed by the engine 1. However, when the charge amount of the traveling battery 10 is equal to or less than a predetermined value, the engine 1 is also started. The battery 10 for traveling is charged by transmitting the driving force of the engine 1 to the motor 2 via the road surface during normal traveling, and regenerating the motor 2 by disconnecting the clutch 4 during deceleration. Do that.
[0012]
During the above-described traveling or the like, the throttle control of the engine 1 is performed according to a throttle control map (not shown), and the ECU 11 controls the throttle actuator so as to achieve the target throttle opening tgtTPS obtained from the map based on the accelerator operation amount APS. 19 is driven and controlled.
Further, the shift control is performed according to a shift control map (not shown), and the ECU 11 performs the shift, clutch, and throttle so as to achieve the target shift stage obtained from the map based on the accelerator operation amount APS and the vehicle speed V. The actuators 17 to 19 are driven and controlled.
[0013]
Next, the control state of the motor torque performed by the motor torque control device of the hybrid vehicle configured as described above when the motor is running will be described.
FIG. 2 is a flowchart showing a target motor torque setting routine, and the ECU 11 executes this routine at a predetermined control interval. First, the ECU 11 calculates the accelerator torque apsT from the following equations (1) and (2) in step S2.
[0014]
MTR1 = tgti × defi / moti (1)
apsT = apsET × MTR1 (2)
Here, MTR1 is a coefficient for converting the torque on the engine 1 side to the torque on the motor 2 side, tgti is the gear ratio of the target gear set by the shift control, defi is the gear ratio of the differential 6, and moti is This is the overall gear ratio of the speed reducer 7 and differential 8 on the motor 2 side. Further, apsET is the accelerator equivalent engine torque, and is obtained from the clutch rotational speed Nc and the accelerator operation amount APS based on the torque map set from the characteristics of the engine 1.
[0015]
That is, the torque map is defined by the engine rotational speed and the throttle opening TPS, but the engine 1 is separated from the front wheel 3a side and stopped by clutch disconnection while the motor is running. Instead of this, the clutch rotational speed Nc is applied. Further, since the throttle opening TPS correlates with the accelerator operation amount APS via the throttle control map, after reflecting this correlation on the torque map, the direct throttle operation amount APS is replaced with the throttle opening TPS. Applicable. The accelerator equivalent engine torque apsET determined in this way means the engine torque achieved during engine running by the current accelerator operation amount APS, and the driving force equivalent to the driving force generated on the front wheels 3a is reduced by the engine torque. A motor torque that can be generated in the wheel is calculated as an accelerator torque apsT.
[0016]
In the subsequent step S4, the creep torque creepT is calculated from the following equations (3) and (4) (creep torque calculating means, braking torque calculating means) .
MTR2 = 1 / moti (3)
creepT = {[(K + g × sinθ) × W−Fbk] × Rty} × MTR2 (4)
Here, MTR2 is a coefficient for converting the torque of the rear wheel 3b into motor torque, K is a target acceleration at the time of creep on a flat road, g is gravitational acceleration, sinθ is a gradient of a road on which the vehicle is traveling, and W is The vehicle weight, Fbk, which is known in advance, is the braking force acting on the front and rear wheels 3a, 3b, and Rtyre is the tire radius.
[0017]
The target acceleration K at the time of creep is obtained from the map of FIG. 3, and is set at a vehicle speed V equal to or lower than a predetermined value that requires the creep phenomenon. Although not described in detail, the road gradient sin θ is based on the difference between the driving force of the vehicle and various resistances such as acceleration resistance and traveling resistance acting on the vehicle, as described in, for example, JP-A-11-8912. Calculated (road gradient detection means). The brake force Fbk is obtained from a preset map (brake force detecting means) based on the brake oil pressure Pbk detected by the brake oil pressure sensor 15 (correlating with the brake force Fbk).
[0018]
That is, in the present embodiment, the original creep torque ([(K + g × sinθ) × W] × Rtyre in the above equation (4), which is to be applied to the rear wheel 3b in order to generate the creep phenomenon , and the creep torque calculating means The braking side torque (Fbk × Rtyre , calculated by the braking torque calculating means ) obtained from the braking force Fbk is subtracted from the calculated value obtained by (1 ). As a result, a value obtained by subtracting the useless torque consumed by the brake operation is calculated as the net creep torque creepT (motor torque control means).
[0019]
Next, in step S6, the temporary motor torque 0-MT is calculated from the following equation (5).
0-MT = apsT × gainC + creepT × (1-gainC) (5)
Here, gainC is a weighting coefficient, and is set based on the accelerator operation amount APS according to the map of FIG. As shown in the figure, in a region where the accelerator operation amount APS is small, a small weighting coefficient gainC (<0.5) is set, and a value closer to the creep torque creepT than the accelerator torque apsT is calculated as the temporary motor torque 0-MT. The As the accelerator operation amount APS increases, the weighting coefficient gainC also increases with a predetermined gradient, and accordingly, a value close to the accelerator torque apsT is calculated as the temporary motor torque 0-MT, and the accelerator operation amount APS greater than or equal to the predetermined value. Then, the weighting coefficient gainC is set to 1.0, and the accelerator torque apsT is calculated as the temporary motor torque 0-MT.
[0020]
In the subsequent step S8, the accelerator torque apsT and the temporary motor torque 0-MT are compared, the larger value is set as the target motor torque tgtMT, and then the routine is terminated. Then, based on the target motor torque tgtMT set as described above, the inverter 9 controls the motor torque at the time of shifting.
As a result of the above processing, when the vehicle stops, for example, when waiting for a signal on a flat road, the accelerator operation amount APS and the vehicle speed V are both 0, so the accelerator torque apsT is set to 0 or a minute value according to the above equation (2). On the other hand, the creep torque creepT is set to the maximum value by the above equation (4). In the above equation (5), a small weighting coefficient gainC is applied to calculate the temporary motor torque 0-MT close to the creep torque creepT, and the temporary motor torque 0-MT is set as the target motor torque tgtMT. Therefore, a motor torque close to the creep torque creepT is generated and a creep phenomenon is produced.
[0021]
On the other hand, when the accelerator is stepped on to start the vehicle from the stopped state, the accelerator torque apsT increases as the accelerator operation amount APS increases, while the creep torque creepT decreases as the vehicle speed V increases. Since the weighting coefficient gainC increases as the accelerator operation amount APS increases, the temporary motor torque 0-MT calculated by the above equation (5) gradually increases from the creep torque creepT to a value close to the accelerator torque apsT. Change. The temporary motor torque 0-MT is balanced to a value determined by the accelerator operation amount APS, the vehicle speed V, and the like. For example, after shifting from start to constant speed running, a weighting coefficient of about 1.0 with the increase of the accelerator operation amount APS. gainC is set, and the temporary motor torque 0-MT is balanced with the accelerator torque apsT. In this way, the accelerator torque apsT is reflected in the motor torque, and the start according to the accelerator operation is realized.
[0022]
Here, depending on various conditions such as the accelerator operation amount APS and the vehicle speed V, the temporary motor torque 0-MT may be transiently set to a value smaller than the driver's accelerator operation amount APS. For example, when the creep torque creepT decreases due to an increase in the vehicle speed V, a transient drop occurs in the temporary motor torque 0-MT. At this time, the accelerator torque apsT which means the driver's required torque is selected in step S8, and a temporary drop of the motor torque is prevented beforehand.
[0023]
In this embodiment, according to the above equation (4), not only the road gradient sinθ but also the braking force Fbk is considered in the creep torque creepT, and the creep torque according to the braking side torque (Fbk × Rtyre) obtained from the braking force Fbk. CreepT is corrected to decrease. As a result, the necessary minimum creep torque creepT obtained by always subtracting the useless torque consumed by the brake operation is set, so that the power consumption of the motor 2 is reduced and the brake force Fbk required for holding the vehicle stopped is reduced. This reduces the driver's labor.
[0024]
In addition, since the creep torque creepT is corrected steplessly in accordance with the braking force Fbk as described above, a creep torque consistent with the driving state is always realized. For example, when the brake operation is stopped to start from waiting for a signal, the creep torque creepT is gradually raised according to the decrease in the braking force Fbk, so that the vehicle can start smoothly, and the vehicle moves forward at a slow speed in a traffic jam. However, even when the distance from the preceding vehicle is adjusted by the brake, the creep torque creepT gradually increases / decreases according to the braking force Fbk, and the smooth distance adjustment becomes possible. As a result, according to the vehicle motor torque control apparatus of the present embodiment, it is possible to generate an appropriate creep torque in accordance with the brake operation and to realize a smooth operation without a sense of incongruity.
[0025]
This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in the above-described embodiment, the vehicle is embodied as a hybrid vehicle in which the front wheel 3 a is driven by the engine 1 and the rear wheel 3 b is driven independently by the motor 2. 3b may be driven, and a motor 2 may be connected to the transmission 5 of the engine 1 so that the motor 2 can drive the rear wheels 3b. Moreover, it may replace with a hybrid vehicle and may be actualized as a motor torque control apparatus of an electric vehicle.
[0026]
【The invention's effect】
As described above, according to the motor torque control device for a vehicle of the present invention, it is possible to generate an appropriate creep torque in accordance with a brake operation and to realize a smooth driving without a sense of incongruity.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing a torque control device for a hybrid vehicle according to an embodiment.
FIG. 2 is a flowchart showing a target motor torque setting routine executed by an ECU.
FIG. 3 is an explanatory diagram showing a map for setting a target acceleration K during creep.
FIG. 4 is an explanatory diagram showing a map for setting a weighting coefficient gainC.
[Explanation of symbols]
2 Motor 11 ECU (road gradient detection means, brake force detection means, motor torque control means)
15 Brake sensor (brake force detection means)
16 Vehicle speed sensor (vehicle speed detection means)

Claims (1)

In a motor torque control device for a vehicle equipped with a motor as a power source,
Vehicle speed detection means for detecting the vehicle speed;
Road gradient detecting means for detecting the road gradient;
Braking force detection means for detecting the braking force of the vehicle;
A creep torque calculating means for calculating a creep torque to be generated on the drive wheels of the vehicle based on the vehicle speed detected by the vehicle speed detecting means and the road gradient detected by the road gradient detecting means;
Braking torque calculating means for calculating a braking-side torque acting on the drive wheel by a brake operation based on the braking force detected by the braking force detecting means;
When the driver's accelerator operation is not being performed, the braking torque calculated by the braking torque calculating means is subtracted from the creep torque calculated by the creep torque calculating means, and based on the creep torque after subtraction. motor torque control apparatus for a vehicle, characterized in that a motor torque control means for controlling the motor.

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