JP2795445B2 - Electric vehicle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vehicle equipped with a motor (electric motor) as a driving force source, and more particularly to an electric vehicle provided with a motor corresponding to each wheel. It is.

[Prior Art] Conventionally, an electric vehicle equipped with one motor as a driving force source is known. In such an electric vehicle, there is a limitation that the driving force is limited, and if the driving force is increased, slipping or the like is likely to occur.

On the other hand, as shown in FIG. 6, there has been proposed an electric vehicle having a four-wheel independent drive system in which a motor is provided as a driving force source corresponding to each wheel. 6, 61 to 64 indicate wheels, and 65 to 68 indicate motors. In such an electric vehicle, slipping is less likely to occur and driving performance is improved as compared to the electric vehicle equipped with only one motor as described above. However, even in the conventional one, since the plurality of motors 65 to 68 are always controlled to be balanced so as to have the same output,
There were still slips on hills, sudden accelerations and sudden braking. This is because, for example, during rapid acceleration, the load is generally applied to the rear wheel more than the front wheel, and the frictional force between the rear wheel and the road surface increases, but the front wheel slips because the frictional force between the front wheel and the road surface decreases. It is a mess.

[Problem to be Solved by the Invention] The present invention is to solve the above-mentioned problem, and based on a load on each wheel and a driving force value required for the vehicle, For wheels with a large load, the driving force distribution increases according to the driving force required,
In addition, according to the driving force required for the wheels whose load is small, the motor driving each wheel is controlled so that the driving force distribution is reduced, and the necessary driving force for the entire vehicle is secured. It is an object of the present invention to provide an electric vehicle having good running performance, high stability, and high safety.

[Means for Solving the Problems] For that purpose, the electric vehicle described in claim 1 is
In an electric vehicle in which motors are individually connected to a plurality of wheels as driving force sources, a load detecting means (1) for detecting a load on each wheel of the electric vehicle, and a driving force required for the electric vehicle is detected. Required driving force detecting means (21)
And, based on the load on each wheel and the required driving force detected by the load detecting means and the required driving force detecting means, drive the wheels of the respective wheels having a large load in accordance with the required driving force. A calculating means (2) for determining a driving force command value for each of the motors so that the wheels having a smaller load have a smaller driving force distribution in accordance with the required driving force so that the force distribution is increased; Control means (3) for controlling the driving force of each motor based on the driving force command value determined by the calculating means.

An electric vehicle according to claim 2, wherein the electric vehicle according to claim 1, wherein a steering angle detecting means (24) for detecting a steering angle of the electric vehicle.
Wherein the calculating means includes first correcting means (34) for correcting the determined driving force command value based on the steering angle from the steering angle detecting means. I do.

An electric vehicle according to a third aspect of the present invention is the electric vehicle according to the first aspect, further comprising a temperature detection unit (25) for detecting a temperature of each of the motors, and the arithmetic unit (2). A second correcting means for correcting the determined driving force command value based on the temperature from the temperature detecting means;
It is characterized by having.

An electric vehicle according to a fourth aspect of the present invention is the electric vehicle according to the first aspect, wherein the calculating means (2) is configured to execute the determination when a slip of a wheel of the electric vehicle is detected. A third correction means (36) for correcting the set driving force command value.

[Operation and Effect of the Invention] In the electric vehicle according to claim 1, the load among the wheels is determined based on the load on the wheels and the required driving force detected by the load detecting means and the required driving force. Each wheel is driven such that the driving force distribution is increased in accordance with the required driving force for wheels that are large and the driving force distribution is decreased in accordance with the required driving force for wheels that are small in load. The motor is controlled.

The validity and rationality of this is clear. This is because the frictional force F between the wheels and the road surface is represented by F = μ × N, where μ is the road surface friction coefficient and N is the load on the wheels. The road surface friction coefficient μ is the same for all wheels. This is because the frictional force of the wheel with a large load on the road surface increases, and the frictional force of the wheel with a small load on the road surface decreases.

Therefore, for a wheel motor with a large load,
Even if a large distribution of the driving force is given according to the required driving force, no slip occurs because the frictional force between the wheel and the road surface is large. In addition, for a motor of a wheel whose load is small, the frictional force between the wheel and the road surface is small, so that the distribution of the driving force is reduced according to the required driving force, so that the slip does not occur. ing. Therefore, according to the first aspect of the invention, no slip occurs on all the wheels.

Further, since the slip means that the wheels are idling, the conventional vehicle can transmit only a driving force less than the required driving force to the road surface. Therefore, the driving force corresponding to the required driving force can be transmitted to the road surface properly.

As described above, according to the present invention, it is possible to reliably prevent the occurrence of slippage of each wheel while sufficiently securing the driving force required as a vehicle, and to improve traveling performance. In addition, stability during running can be improved.

In the electric vehicle described in claim 2, the driving force command value determined based on the steering angle of the electric vehicle is corrected, so that the driving force can be commanded in consideration of the inner wheel difference.

Further, in the electric vehicle described in claim 3, since the driving force command value determined based on the temperature of each motor is corrected, disconnection and seizure of each motor coil can be prevented.

Further, in the electric vehicle according to the present invention, when the wheels of the electric vehicle slip, the determined driving force command values are corrected, so that even when the wheels slip, the road surface grip is optimized. be able to.

Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an electric vehicle according to the present invention, FIG. 2 is a diagram showing an embodiment thereof, and FIG. 3 is a diagram showing processing by a calculation means in the embodiment shown in FIG. FIG. 4 is a view for explaining the flow, FIG. 4 is a view showing an embodiment of a load sensor, and FIG. 5 is an explanatory view of an embodiment using an acceleration sensor as the load sensor. FIG. 6 is a diagram showing a configuration example of an electric vehicle suitable for applying the present invention.

First, as shown in FIG. 1, the present invention provides a detecting means 1 for detecting a load on each wheel 61 to 64 of an electric vehicle, a detection value of the detecting means 1 and a driving force value required for the electric vehicle. Calculating means 2 for determining a driving force command value for each of the motors 65 to 68 corresponding to the wheels 61 to 64 based on the driving force command values of the motors 65 to 68 based on the driving force command value of the calculating means 2. Control means 3 for controlling the driving force (output).

FIG. 2 shows an embodiment of the present invention, in which a detection value of a load sensor 1 is input to a calculating means 2 and an accelerator pedal of the vehicle is used as a signal of a driving force value required for the electric vehicle.
A value of 21 is input. As the motors 65 to 68 in this case, for example, DC brushless motors can be used. In addition, an output signal of the forward / reverse / neutral switch 23 is input to the arithmetic means 2 to determine the direction of the driving force of each of the motors 65 to 68, that is, the rotation direction, and the driving force at the time of braking is determined. Therefore, the value of the amount of depression of the brake pedal 22 is input. Further, in this embodiment, in order to correct the driving force command value of each of the motors 65 to 68, in addition to the above values, the detection value of the steering angle sensor 24 and the motor temperature provided for each of the motors 65 to 68 The detection values of the sensors 25 to 28 are input. In FIG. 2, 3 (1) to 3 (4)
Is a motor driver as motor control means.

The flow of processing in the arithmetic means 2 in the embodiment of FIG. 2 will be described with reference to FIG.

In the calculating means 2 in this embodiment, after taking in the values of the respective sensors and the like (31), first, the depression amount of the accelerator pedal 21 and the depression amount of the brake pedal 22 are compared to judge whether it is during driving or braking. (32). Here, when the signal of the accelerator pedal depression amount is input,
It is determined that the motor is being driven (YES), and the motor 65- is determined based on the accelerator pedal depression amount and the detected value of the load applied to each wheel.
The driving force command value for each 68 is determined (33).

Here, in order to detect the load applied to each of the wheels 61 to 64,
For example, a load sensor may be provided for each of the wheels 61 to 64.
FIG. 4 shows an example of the configuration of the load sensor in this case. 4th
In the figure, 41 is a wheel, 42 is a motor, 43 is a torque link, 44 is a suspension spring, 45 is a vehicle body frame, and 46 is a load sensor body. In this embodiment, the load sensor body 46 is configured as a potentiometer, and one of a non-sliding body (resistor) and a sliding body is moved to the vehicle body frame 45 and the other is moved integrally with the motor 42. Attached to. The load applied to the wheel 41 is detected from the amount of compression of the suspension spring 44.

When the detected load values of the wheels 61 to 64 thus detected are a, b, c, and d, respectively, in the process (33), the driving force command value for each of the motors 65 to 68 is determined. Is determined as follows, for example, according to the ratio of these load detection values.

-Command value for motor 65: (a / K) x A-Command value for motor 66: (b / K) x A-Command value for motor 67: (c / K) x A-Command value for motor 68: ( d / K) × A (where K = a + b + c + d, or A is the amount of depression of the access pedal) FIG. 5 shows still another configuration example for detecting the load applied to each of the wheels 61 to 64.

In this configuration example, the acceleration sensor 51 is mounted on the electric vehicle. The acceleration sensor 51 is preferably installed near the center of gravity of the electric vehicle. Then, the inclination of the vehicle body is detected from the detection value of the acceleration sensor 51. Since the inclination of the vehicle body indicates the direction in which the load is applied, an amount corresponding to the load applied to each of the wheels 61 to 64 can be detected in this case as well.

In the embodiment of FIG. 5, the amount proportional to the component force of the detected value (vector) of the acceleration sensor 51 is a in the axial direction of the vehicle body and b in the direction orthogonal thereto as shown in FIG. In this case, in the process (33), the driving force command value for each of the motors 65 to 68 is determined based on these values of a and b, for example, as follows.

-Command value for motor 65: (A / 4)-ab-Command value for motor 66: (A / 4)-a + b-Command value for motor 67: (A / 4) + a-b-Command for motor 68 Value: (A / 4) + a + b (where A is the accelerator pedal depression amount) Normally, the driving force command value obtained by the process (33) in this manner can be used as it is. Then, the driving force command value is set to the value of the steering angle,
Correction is made based on the motor temperature and the presence or absence of wheel slip. Here, in the correction (34) based on the value of the steering angle, for example, when the steering angle is large, the driving force command value of the motor driving the innermost wheel is processed in consideration of the so-called "inner wheel difference". The driving force command value obtained by (33) is reduced. In addition, in the correction (35) based on the motor temperature, when the motor temperature exceeds or is predicted to exceed the allowable amount, the driving force command value is suppressed in order to prevent disconnection or burn-in of the motor coil. ing. Further, in the correction by wheel slip (36), when wheel slip is detected, in order to optimize the grip on the road surface, the driving force command value for the motor driving the wheel on which the slip has been detected is set. Is to be reduced. It should be noted that these corrections are not essential components of the present invention and can be omitted, and it is needless to say that other corrections can be added as needed.

Returning to the determination (32), when a signal indicating the amount of depression of the brake pedal 22 is input, it is determined that braking is being performed (NO), and a braking force command value is determined based on the amount of depression of the brake pedal ( 37). In the electric vehicle, at the time of braking, regenerative braking in which a drive source motor operates as a regenerative brake can be performed.

When the driving force command value or the braking force command value is determined by the above processes (33 to 37) as described above, finally, the rotation direction of the motor is determined based on the input value from the forward / reverse / neutral switch 23. (38). The driving force command value or the braking force command value and the rotation direction determined in this way are controlled by the control means 3 shown in FIG.
The power is transmitted to (1) to 3 (4) (39), and the power supplied to each of the motors 65 to 68 is controlled to control the driving force (output).

As is clear from the above description, according to the present invention, the driving force command value of the motor corresponding to each wheel is determined based on the load value for each wheel and the driving force required for the vehicle. Since each motor is separately determined and controlled, it is possible to reliably prevent the occurrence of slippage of each wheel while ensuring sufficient driving force required for the vehicle, and to improve running performance. And stability and safety during running can be enhanced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an electric vehicle according to the present invention, FIG. 2 is a diagram showing one embodiment thereof, and FIG. 3 is a flow chart showing a process flow in a calculation means in the embodiment shown in FIG. Figure to do
FIG. 4 is a diagram showing an embodiment of a load sensor, FIG. 5 is an explanatory view of an embodiment using an acceleration sensor as a load sensor, and FIG. 6 is a configuration example of an electric vehicle suitable for applying the present invention. FIG. 1 ... Load detecting means, 2 ... Calculating means, 3, 3 (1) ~
3 (4) Control means 21 Accelerator pedal 22
Brake pedal, 23: Forward / reverse / neutral switch, 24: Steering angle sensor, 25-28 ...
… Motor temperature sensor, 41, 61-64 …… Wheels, 42, 65-68
………………………………………………………………………………………………………………………………………………………………………………………………….

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-195033 (JP, A) JP-A-63-163906 (JP, A) JP-A-63-133804 (JP, A) JP-A-57-133 78855 (JP, A) Japanese Utility Model Showa 59-141405 (JP, U) Japanese Patent Publication No. 48-30340 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60L 15/20

Claims (4)

(57) [Claims] An electric vehicle in which motors are individually connected to a plurality of wheels as a driving force source. A load detecting means (1) for detecting a load on each wheel of the electric vehicle; Required driving force detecting means (21) for detecting a driving force, and a load among the wheels based on the load on each wheel and the required driving force detected by the load detecting means and the required driving force detecting means. For each of the motors, a larger wheel is provided with a larger distribution of driving force according to the required driving force, and a smaller load is provided for each of the motors such that the distribution of driving force is reduced according to the required driving force. An electric vehicle comprising: a calculating means (2) for determining a driving force command value; and a control means (3) for controlling a driving force of each motor based on the driving force command value determined by the calculating means. . 2. A steering angle detecting means (24) for detecting a steering angle of the electric vehicle, wherein the calculating means (2) determines the steering angle based on a steering angle from the steering angle detecting means. The electric vehicle according to claim 1, further comprising a first correction unit (34) configured to correct the driving force command value. 3. A temperature detecting means (25) for detecting a temperature of each of the motors, wherein the calculating means (2) outputs the determined driving force command value based on the temperature from the temperature detecting means. The electric vehicle according to claim 1, further comprising a second correction unit (35) for performing correction. 4. The operation means (2) includes a third correction means (36) for correcting the determined driving force command value when slippage of a wheel of the electric vehicle is detected. The electric vehicle according to claim 1, wherein