JP2002142304A - Motor torque controller for electric vehicle, and motor torque controller for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor torque controller for a hybrid vehicle which can easily drive the vehicle with the same acceleration feeling without discom fort, in both engine driving and motor driving. SOLUTION: In motor driving, an acceleration proportionate engine torque 'apsET' achieved in an engine driving is estimated from a present acceleration and is multiplied by a correction factor MTR, according to a gear ratio to obtain an acceleration torque apsT which is the torque of a motor side (step S2). A target motor torque tgtMT is set according to the acceleration torque apsT and a creep torque 'creepT' obtained by a separated process (step S8). A motor torque is controlled, according to the target motor torque. Using such a constitution, a driving force equivalent to that in the engine driving can always bee obtained in the motor driving, with the same acceleration operation value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor torque control device for electric vehicles and hybrid vehicles.

[0002]

2. Description of the Related Art As a conventional motor torque control apparatus for a vehicle of this type, for example, Japanese Patent Application Laid-Open No.
Japanese Unexamined Patent Publication (Kokai) No. H10-15064 can be mentioned. This motor torque control device is applied to a hybrid vehicle, and controls the engine torque as well as the motor torque. However, since the torque characteristics are different between the engine and the motor, the torque generation state with respect to the accelerator operation amount is reduced. Are different. Specifically, the engine has a characteristic in which the torque is maximum in the middle rotation range, so that the engine torque sharply increases in a region where the accelerator operation amount is small, and the engine torque increases gradually with the increase in the accelerator operation amount. On the other hand, the motor linearly increases the torque in proportion to the accelerator operation amount because of the characteristic that the motor increases the torque with the rotation speed.

[0003]

As is well known, in a hybrid vehicle, engine running and motor running are switched according to running conditions such as acceleration, constant speed running, and deceleration, or the amount of battery charge. Therefore, as described above, when the torque generation states of the engine and the motor with respect to the accelerator operation amount of the driver are different, not only does the driver feel uncomfortable, but also the driving operation becomes difficult.

[0004] On the other hand, for example, in the case of a commercial vehicle, it is often the case that a plurality of salesmen change over to the same vehicle type so as not to be confused by the driving operation. However, when an engine vehicle and an electric vehicle are mixed in this business vehicle, the torque generation state differs with respect to the accelerator operation amount due to the difference in torque characteristics, and when the engine vehicle and the electric vehicle are switched, In this case, the above-mentioned inconvenience such as discomfort occurs.

Accordingly, an object of the present invention is to provide a motor torque control device for an electric vehicle that can be easily driven with the same accelerator operation feeling without feeling uncomfortable even when switching from an engine vehicle. Is to do. It is another object of the present invention to provide a motor torque control device for a hybrid vehicle that can be easily driven with the same accelerator operation feeling without discomfort when the engine is running and when the motor is running. It is in.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, the accelerator operation amount and the torque generated on the drive wheels by the motor are compared with the torque characteristics of the engine vehicle driven by the engine. The motor torque is controlled so that the relationship between them is the same. Therefore, for example, when an engine vehicle and an electric vehicle of the same vehicle type are set as commercial vehicles, torque characteristics with respect to the accelerator operation amount and the engine rotation speed are obtained based on the engine torque map of the engine vehicle. When the same gear ratio as that of the drive system of the engine vehicle is adopted in the electric vehicle, the motor torque is controlled according to this torque characteristic,
When different gear ratios are employed, the motor torque is controlled in accordance with the torque characteristics corrected according to the gear ratio. As a result, a driving force equal to that of the engine vehicle is always obtained with the same accelerator operation amount.

According to a second aspect of the present invention, there is provided a hybrid vehicle capable of switching between engine running and motor running.
An engine torque estimating means for estimating an engine torque achieved at the time of engine running based on a current accelerator operation amount during motor running, a target motor torque setting means for setting a motor torque corresponding to the estimated engine torque as a target value, and a target motor Motor torque control means for controlling the motor torque based on the torque.

[0008] Therefore, when the engine is running, the engine torque is adjusted in accordance with the accelerator operation by the driver, and acceleration,
A desired traveling state such as constant speed traveling and deceleration can be obtained. On the other hand, at the time of motor traveling, the engine torque achieved at the time of engine traveling by the current accelerator operation amount is estimated by the engine torque estimating means, and corresponds to the estimated engine torque. The target motor torque to be set is set by target motor torque setting means. For example, when the gear ratio for the drive wheels is the same for the engine and the motor, a target motor torque equivalent to the engine torque is set, and when the gear ratio for the drive wheels is different, a correction according to the gear ratio is added. And a target motor torque is set. Since the motor is controlled based on the target motor torque, a driving force equivalent to that at the time of engine running is always obtained with the same accelerator operation amount.

Further, according to the invention of claim 3, the engine torque estimating means calculates the engine torque based on the accelerator operation amount correlated with the throttle opening of the engine and the rotational speed of the drive source shaft correlated with the engine rotational speed. It was configured to estimate. While the motor is running, the engine is stopped after being disconnected from the drive wheels by disengaging the clutch. However, even in this case, the throttle opening of the engine can be controlled mechanically with a wire or the like or according to a map. It can be estimated on the basis of the accelerator operation amount having a predetermined correlation, and the engine rotation speed can be estimated from the rotation speed of the drive source shaft. Then, by comparing the throttle opening and the engine rotation speed with a torque map specific to the engine, it is possible to estimate the engine torque corresponding to the running state at that time.

On the other hand, in the invention of claim 4, since the rotation speed of the drive source shaft is used as the output rotation speed of the clutch, the engine rotation speed can be estimated from the output rotation speed of the clutch.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a motor torque control device for a hybrid vehicle will be described below. FIG. 1 is an overall configuration diagram showing a torque control device for a hybrid vehicle according to the present embodiment. As shown in FIG.
In the hybrid vehicle of the present embodiment, the engine 1 side and the motor 2 side are configured independently of each other including a drive system, and the front wheels 3a are driven by the engine 1 and the rear wheels 3b are driven by the motor 2. It has become. To elaborate,
An automatic transmission 5 is connected to a gasoline engine 1 mounted on the front side of the vehicle via a clutch 4, and the engine 1 is connected via the automatic transmission 5 and a differential 6.
Is transmitted to the front wheel 3a side. The basic configuration of the automatic transmission 5 is the same as that of a general mechanical transmission that performs a manual gear shift operation. However, as described later, the automatic gear shift operation, the clutch operation, and the throttle operation of the engine 1 are automated. , So that automatic shifting is possible.

A reduction gear 7 of a planetary gear type is connected to the motor 2 mounted on the rear side of the vehicle, and the rotation of the motor 2 is transmitted through the reduction gear 7 and the differential 8 to rear wheels 3b as drive wheels. Transmitted to the side. A running 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, in the vehicle interior, an input / output device (not shown) and a storage device (ROM, RAM
Etc.), an ECU 11 (electronic control unit) including a central processing unit (CPU), a timer counter, and the like. An accelerator sensor 12 for detecting an accelerator operation amount APS by the driver, an engine 1
Throttle sensor 1 that detects the throttle opening TPS of the throttle
3. A clutch rotational speed sensor 14 for detecting the rotational speed Nc on the output side (transmission side) of the clutch 4 (the clutch rotational speed Nc may be estimated from the vehicle speed V instead of the sensor 14), and the brake Various sensors such as a brake oil pressure sensor 15 for detecting the oil pressure Pbk of the vehicle and a vehicle speed sensor 16 for detecting the vehicle speed V are connected. On the output side of the ECU 11, a shift actuator 17 for performing a shift operation of the automatic transmission 5, a clutch actuator 18 for connecting and disconnecting the clutch 2, a throttle actuator 19 for opening and closing a throttle valve of the engine 1, And the inverter 9 and the like.

In the hybrid vehicle of the present embodiment, the start is basically performed by the motor 2 and the subsequent running 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 also starts. or,
The charging of the traveling battery 10 is performed by transmitting the driving force of the engine 1 to the motor 2 via the road surface during normal traveling, and by regenerating the motor 2 by disengaging the clutch 4 during deceleration. Do.

At the time of running or the like, the throttle control of the engine 1 is performed according to a throttle control map (not shown), and the ECU 11 determines a target throttle opening degree tgtTPS obtained from the map based on the accelerator operation amount APS.
Is controlled to achieve the above. The shift control is performed according to a shift control map (not shown), and the ECU 11 controls the shift, clutch, and throttle so as to achieve the target shift speed obtained from the map based on the accelerator operation amount APS and the vehicle speed V. Of each of the actuators 17 to 19 is controlled.

Next, a description will be given of the control state of the motor torque performed by the motor torque control device of the hybrid vehicle configured as described above during motor running. FIG. 2 is a flowchart showing a target motor torque setting routine.
1 executes this routine at a predetermined control interval. First, in step S2, the ECU 11 calculates the accelerator torque apsT from the following equations (1) and (2).

MTR1 = tgti × defi / moti (1) apsT = apsET × MTR1 (2) where MTR1 is a coefficient for converting the torque on the engine 1 side into the torque on the motor 2 side. Here, 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 the overall gear ratio of the speed reducer 7 and the differential 8 on the motor 2 side. or,
apsET is the accelerator-equivalent engine torque, which is obtained from the clutch rotation speed Nc and the accelerator operation amount APS based on the torque map set from the characteristics of the engine 1 (engine torque estimating means).

That is, the torque map is defined by the engine rotational speed and the throttle opening TPS. During the motor running, the engine 1 is separated from the front wheels 3a by the clutch disconnection and stopped. The clutch rotation speed Nc is applied instead of the engine rotation speed. Also, since the throttle opening TPS is correlated with the accelerator operation amount APS via the throttle control map,
After reflecting this correlation in the torque map, the accelerator operation amount APS is directly applied instead of the throttle opening TPS. The accelerator-equivalent engine torque apsET obtained in this way means the engine torque achieved during the engine running with the current accelerator operation amount APS, and the rearward driving force equivalent to the driving force generated in the front wheels 3a by the engine torque is obtained. The motor torque that can be generated on the wheels is
It is calculated as accelerator torque apsT (target motor torque setting means).

In the following step S4, a creep torque creepT is calculated from the following equations (3) and (4). MTR2 = 1 / moti (3) creepT = {[(K + g × sinθ) × W-Fbk] × Rtyre} × MTR2 (4) where MTR2 is the torque of the rear wheel 3b as the motor torque. K is the target acceleration during creep on a flat road, g is the gravitational acceleration, sinθ is the gradient of the road on which the vehicle is traveling, W is the vehicle weight known in advance, and Fbk is the front and rear wheels 3a, The braking force acting on 3b, Rtyre, is the tire radius.

The target acceleration K during creep is obtained from the map shown in FIG. 3, and is set at a vehicle speed V equal to or lower than a predetermined value that requires a 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 running resistance acting on the vehicle, as described in Japanese Patent Application Laid-Open No. 11-8912. Is calculated.
Further, the braking force Fbk is determined by the brake oil pressure sensor 1 described above.
Based on the brake oil pressure Pbk (correlated with the brake force Fbk) detected at step 5, it is determined from a preset map.

That is, in the present embodiment, the original creep torque to be applied to the rear wheel 3b in order to generate the creep phenomenon ([(K + g × sin θ) × W] × R in the above equation (4))
(tyre), the braking torque (Fbk × Rtyre) calculated from the braking force Fbk is subtracted. As a result, a value obtained by subtracting unnecessary torque consumed by the brake operation is calculated as a net creep torque creepT.

Next, in step S6, a provisional 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. You. Then, as the accelerator operation amount APS increases, the weighting coefficient gainC
Also increases with a predetermined gradient, and a value close to the accelerator torque apsT is calculated as the provisional motor torque 0-MT accordingly, and the weighting coefficient gainC is set to 1.0 for the accelerator operation amount APS equal to or larger than the predetermined value, and Torque aps
T is calculated as temporary motor torque 0-MT.

In the following step S8, the accelerator torque aps
T is compared with the provisional motor torque 0-MT, and the larger value is set as the target motor torque tgtMT, and then the routine ends. Then, based on the target motor torque tgtMT set as described above, the motor torque at the time of shifting is controlled by the inverter 9 (motor torque control means).

According to the above processing, for example, when the vehicle is stopped due to a signal waiting on a flat road, etc., the accelerator operation amount APS and the vehicle speed V are both 0. Therefore, according to the above equation (2), the accelerator torque apsT becomes 0 or a very small value. While
According to the above equation (4), the creep torque creepT is set to the maximum value. Then, in the above equation (5), a small weighting coefficient gainC
Is applied to calculate the provisional motor torque 0-MT close to the creep torque creepT, and the provisional motor torque 0-MT is set as the target motor torque tgtMT. Therefore,
A motor torque close to creep torque creepT is generated, and a creep phenomenon is produced.

On the other hand, when the accelerator is depressed 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 gain C increases with the increase in the accelerator operation amount APS, the provisional motor torque 0-MT calculated by the above equation (5) gradually becomes creep torque creep torque creep.
It changes from T to a value close to the accelerator torque apsT. The provisional 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 the vehicle shifts from the start to the constant speed running, a weighting coefficient of about 1.0 is increased with the increase in the accelerator operation amount APS. When the gain C is set, the provisional 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.

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, the provisional motor torque 0-MT
, A transient drop occurs. At this time, the accelerator torque ap which means the required torque of the driver is determined in step S8.
sT is selected to prevent a temporary drop in the motor torque.

As is clear from the above description,
When the motor is running other than at the time of stopping or starting which causes the creep phenomenon, the motor 2 is controlled substantially based on the accelerator torque apsT. Then, the above-described step S
In the case of No. 2, the accelerator-equivalent engine torque apsET achieved at the time of engine running with the current accelerator operation amount APS
Is calculated, and the value is converted into the torque on the motor 2 side to calculate the accelerator torque apsT. In other words, the motor 2 is controlled with a torque characteristic simulating the torque characteristic of the engine 1, and a driving force equivalent to that during engine running is generated with the same accelerator operation amount APS.

As a result, the driver can easily drive with exactly the same accelerator operation feeling during engine running and motor running without feeling uncomfortable. In addition, since the driving force of the vehicle does not fluctuate even when switching is performed between the engine traveling and the motor traveling, there is an advantage that a shock caused by the fluctuation of the driving force can be prevented beforehand.

Although the embodiment has been described above, aspects of the present invention are not limited to this embodiment. For example, in the above embodiment, the present invention is embodied as a motor torque control device for a hybrid vehicle, but may be embodied as a motor torque control device for an electric vehicle. For example, if an engine vehicle and an electric vehicle of the same model are set as business vehicles,
In order for a plurality of salesmen to drive without confusion, it is desirable to unify the accelerator operation feeling between the engine vehicle and the electric vehicle. Therefore, in such a case, the engine vehicle is regarded as a simulation target, and the motor torque of the electric vehicle is controlled so as to generate a driving force equivalent to that of the engine vehicle at the same accelerator operation amount APS.

More specifically, a torque characteristic (a characteristic of an accelerator equivalent engine torque apsET) with respect to an accelerator operation amount APS and an engine rotational speed is obtained in advance based on a torque map of the engine vehicle to be simulated. If the same gear ratio as that of the drive system of the engine vehicle is used, the motor torque is controlled in accordance with this torque characteristic, and if a different gear ratio is used, correction according to the gear ratio is performed. If the motor torque is controlled in accordance with the added torque characteristics, the same driving force as that of the engine vehicle is always obtained with the same accelerator operation amount APS. As a result, even if the vehicle is switched from the engine vehicle, the same driving force can be obtained without discomfort. Driving can be easily performed with an accelerator operation feeling.

Further, in the above-described embodiment, a hybrid vehicle in which the front wheel 3a is driven by the engine 1 and the rear wheel 3b is driven independently by the motor 2 is embodied. However, the configuration of the vehicle is not limited to this. 1, the rear wheel 3b may be driven, and the motor 2 may be connected to the transmission 5 of the engine 1 so that the motor 2 can drive the rear wheel 3b.

[0031]

As described above, according to the motor torque control device for an electric vehicle according to the first aspect of the present invention, even when the vehicle is switched from the engine vehicle, the driver can easily drive with the same accelerator operation feeling without feeling uncomfortable. can do. or,
According to the motor torque control device for a hybrid vehicle according to the second to fourth aspects of the present invention, it is possible to easily drive the vehicle with the same accelerator operation feeling without discomfort when the engine is running and when the motor is running.

[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 illustrating 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]

Reference Signs List 1 engine 2 motor 3b rear wheel (drive wheel) 11 ECU (engine torque estimation means, target motor torque setting means, motor torque control means)

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Claims (4)

[Claims] The motor torque is controlled such that the relationship between the accelerator operation amount and the torque generated on the drive wheels by the motor is the same as the torque characteristic of the engine vehicle driven by the engine. Motor torque control device for an electric vehicle. 2. A hybrid vehicle capable of switching between engine traveling and motor traveling, wherein during the motor traveling, an engine torque estimating means for estimating an engine torque achieved during the engine traveling by a current accelerator operation amount; Motor torque control for a hybrid vehicle, comprising: target motor torque setting means for setting a motor torque corresponding to torque as a target value; and motor torque control means for controlling motor torque based on the target motor torque. apparatus. 3. The engine torque estimating means estimates an engine torque based on an accelerator operation amount correlated with a throttle opening of the engine and a rotation speed of a drive source shaft correlated with the engine rotation speed. The motor torque control device for a hybrid vehicle according to claim 2. 4. The motor torque control device for a hybrid vehicle according to claim 3, wherein the rotation speed of the drive source shaft is an output rotation speed of a clutch.