JPH02262806A - Electromobile - Google Patents

Abstract

PURPOSE:To perform 4WS or 4WD control without complicating the structure by arranging a drive motor independently for each drive wheel then controlling drive torque and brake torque of the drive motor independently based on signals related to traveling condition of vehicle. CONSTITUTION:Each wheel is provided with a wheel rotation sensor 34 for producing a wheel rotation signal which is employed for calculation of angular acceleration of each wheel. Required brake force and angular acceleration of wheel are obtained based on brake signal, steering signal, vehicle speed, and previously stored limit brake force, then brake force or drive force of a drive motor is operated and corrected in due consideration of pavement condition. Limit value of rotary acceleration of wheel is previously stored in the storage medium of a computer 31 then required driving force and angular acceleration of wheel are operated based on acceleration signal, vehicle speed and limit driving force, thereafter driving force of each drive motor is operated, in due consideration of pavement condition, based on the rotary angular acceleration derived from wheel rotation signal and the required angular acceleration of wheel.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an electric vehicle whose wheels are driven by a motor, and particularly relates to improving the running performance of the electric vehicle.

(Conventional technology) With the recent advancements in automobile technology, 4WS (four-wheel steering) and 4WD have become popular as technologies to improve the driving performance of automobiles.
(four-wheel drive), ABS (anti-skid brake),
New technologies such as traction control have been proposed.

However, since these new technologies involve the driving force of each wheel, implementing them requires adding a new mechanical configuration to the conventional vehicle configuration and controlling it appropriately based on the required conditions. is necessary.

(Problems to be Solved by the Invention) Conventional automobiles have a drive system that distributes the power from a single drive source, the engine, to multiple drive wheels. Mechanisms to be added and mechanical configurations associated with the addition of new mechanisms tend to become complicated due to their relationship with the configuration of the drive system, and this situation is the same in electric vehicles.

The present invention was made based on this background, and aims to provide an electric vehicle concept that does not complicate the mechanical structure and facilitates the implementation of these new technologies.

(Means for Solving the Problems) For this purpose, the present invention provides an electric vehicle in which drive wheels are provided on both sides of the vehicle body, in which a drive motor is installed independently on each of the drive wheels, and these drive motors The driving torque and braking torque of the vehicle are controlled independently using signals based on the running of the vehicle.

(Function) According to the present invention, it is possible to completely avoid the problem of the conventional driving force distribution, and by independently controlling the driving torque and braking torque of each drive motor, the driving force on both sides of the vehicle body can be controlled. It is easy to freely and independently change the circumferential speed of the wheels, the driving force, and the braking force.

Therefore, it is easy to implement these new technologies that involve adjusting the driving force of each wheel, and there is no need for a special mechanical configuration, and new technologies can be implemented with a relatively simple mechanical configuration. It is possible to provide an electric vehicle concept that can implement the following.

(Example) The present invention will be explained below with reference to an example shown in the drawings. This example is a four-wheel electric vehicle configured with a four-wheel drive (hereinafter referred to as 4WD) type, and a four-wheel steering (four-wheel steering) system. Below, 4
WS) function, anti-skid brake (ABS)
It has a traction control function and a traction control function.

First, the configuration of the electric vehicle will be explained with reference to FIGS. 1 and 2.
) A vehicle body 4 is supported by two front wheels 2a, 2b and two rear wheels 3a, 3b arranged on both sides of the vehicle, and a front seat 6 and a rear seat 7 are installed in a vehicle interior 5 formed in the vehicle body 4. ing.

A steering handle 8 is provided in front of the front seat 6, and the steering handle 8 is equipped with a steering device (not shown) such as an Ackermann mechanism.
The front wheels 2a and 2b are connected via the front wheels, and are given the function of a steered wheel.

In addition, front and rear wheels 2a are located in front of the front seat 6.

An accelerator pedal 11 that adjusts the rotational speed of the motors 2b, 3a, and 3b, and a brake pedal 12 that operates a hydraulic brake device (not shown) are installed.

Below the rear seat 7, a battery 13 for driving each drive motor (described later) that drives the front wheels 2a, 2b and rear wheels 3a, 3b is arranged, and behind the rear seat 7, a controller 14 for each drive motor (described later) is arranged. is set up.

The drive device of this electric vehicle 1 is constructed as shown in FIG.

That is, left and right front wheels 2a, 2b and left and right rear wheels 3a.
, 3b are formed in the same way, and a drive motor 21a serves as a drive source for the respective front wheels 2a, 2b and rear wheels 3a, 3b.

A drive shaft 23a extends from 2lb, 22a, 22b.

23 b, 24 a, 24 b are connected to gear boxes 25 a, 25 made up of bevel gears, etc.
b, 261L+26b, and the axle 27a of these front and rear wheels.

27b, 28a, and 28b are configured to be rotationally driven.

Here, the drive motors 21a, 21b, 22a.

22b is driven by the current supplied from the driving battery 13, but each of these is controlled by a signal from the controller 14 and driven independently of each other.

Drive motors 21a and 21b of this electric vehicle 1.

The controller 14 that controls 22a and 22b is configured as shown in FIG.

That is, the controller 14 controls the computers 31 and 4.
two motor controllers 32a, 32b.

33, a, and 33b, and these motor controllers 32a, 32b, 33a, 33
Drive motors 21 a, 2 l b, 22 a, 22 corresponding to the output signals from b
b is independently controlled.

The computer 31 also includes each drive motor 21a,
Rotation speed signals (hereinafter referred to as
(referred to as a wheel rotation signal) and the steering handle 8
Steering angle sensor 3 installed on the steering shaft of
Steering angle signal from 5 (hereinafter referred to as steering signal)
and an accelerator sensor 3 installed on the accelerator pedal 11.
The acceleration command signal detected at step 6 (hereinafter referred to as an accelerator signal) and the braking command signal (hereinafter referred to as a brake signal) detected by a brake sensor 37 installed on the brake pedal 12 are input.

In addition, when obtaining a wheel rotation signal for a non-driven wheel that does not have a drive motor, the wheel rotation sensor 34 may be attached to a wheel or an axle.

These signals are stored in the ROM in the computer 31.
It is calculated according to a program stored in a storage medium such as (Read Only Memory), compared with the stored running data of the electric vehicle 1, and outputs the required output to each motor controller 32a.

32b, 33a, 33b, each drive motor 21a, 2lb,
22a and 22b to an appropriate rotational state and control the driving force and braking force of each wheel.

Hereinafter, 4W Sma, 4WD in this example
The functions, ABSm function, and traction control function will be explained.

First, the 4WS function will be explained with reference to Figures 4 and 5. First, Figure 4 shows that the 4WS function is
The W3 function will be explained.

MO is the turning center of the vehicle caused by operating the steering device with the steering handle 8, and the driving forces ΔFl and ΔF of the front wheels 2b and rear wheels 3b on the outside of the turning are
3, the driving force ΔF of the front wheels 2a and 3a on the inside of the turn
If the corresponding drive motors of each wheel are controlled so as to reduce 2 or to generate braking forces ΔR2 and ΔR4, a steering effect similar to that of a caterpillar vehicle will be produced between the left and right rear wheels 3a and 3b, so the turning center will be The position of M is closer to the vehicle than the MO, and the turning radius of the vehicle becomes smaller4.
WS effect occurs.

In this case, it is preferable to carry out the test under the condition that the resultant force in the longitudinal direction of the vehicle of the driving force generated at each wheel is equalized, since no acceleration in the traveling direction of the vehicle occurs and the running stability of the vehicle is maintained.

Next, the 4WS effect during high-speed running will be explained with reference to FIG.

Generally, when turning at high speed, a transient yawing moment causes the vehicle body to take an attitude facing inward with respect to the instantaneous direction of travel, which may impair the running stability of the vehicle.

In contrast, in this embodiment, the driving force and braking force of each wheel are controlled to generate and offset a moderate amount of yawing moment in the opposite direction, thereby ensuring high-speed stability by matching the instantaneous direction of travel and the orientation of the vehicle body. It aims to improve the quality of life.

In other words, when we consider a right turn as shown in Figure 5, a transient yawing moment occurs in the clockwise direction of the center of gravity in the center of the vehicle, but by controlling each drive motor, driving force is applied to each wheel. Change ΔF2. ΔF4 and braking force changes ΔR1 and ΔR3 are applied, thereby applying a counterclockwise yawing moment to the vehicle body and increasing the clockwise yawing moment to control the vehicle body attitude.

In this case, as the braking force to be applied, regenerative braking by each drive motor may be used.

In addition, in order to prevent acceleration of the construction vehicle in the traveling direction due to the force for controlling the vehicle body posture, the 4WS function during low-speed driving is used to control the resultant force in the longitudinal direction of the vehicle to be equal. The same is true for .

In this way, this embodiment achieves a four-wheel drive (intersecting IF) by appropriately controlling the XK motors of each axle.
Driving stability can be improved, and there is no need to add any special mechanism.

Next, to explain the 4WD function, this electric vehicle 1 has drive motors 21 a, 2 l b, and 22 a for each wheel 2 a, 2 b, 3 a, and 3 b, respectively.

22b, the full-time 4WD function can be achieved by controlling each drive motor to equalize the rotational speed of each wheel in a straight-ahead state.

Generally, when a vehicle with a selective 4WD function turns in four-wheel drive, the distance traveled by the outer wheel and the inner wheel are not equal due to the difference between the inner wheels caused by the turn. , a braking phenomenon occurs due to the inability to differentially move between the front and rear wheels.

However, in the electric vehicle 1 of this embodiment, each of the wheels 2a, 2b, 3a, and 3b has a drive motor, so based on the steering signal from the steering angle sensor 35, Therefore, the rotation speed of the drive motor (e.g., 22a) of the wheel whose distance from the turning center is shortest (e.g., the shortest rear wheel 3a) is changed from that of the wheel whose distance from the turning center is the longest (e.g., the front wheel 2b). This braking phenomenon can be improved by controlling the rotational speed of the drive motor (for example, 21b) by an appropriate amount.

Next, to explain the ABS function, in the electric vehicle of this embodiment, each iL transport 2a, 2b.

A wheel rotation sensor 34 is installed at each of 3a and 3b, and the angular acceleration of each wheel is determined from the wheel rotation signals of these sensors 34, and the angular acceleration of each wheel is determined from the wheel rotation signal of these sensors 34. The required braking force and required wheel angular acceleration are determined from the power, and the braking force and driving force of each drive motor are calculated and corrected after taking into account the road surface conditions.

Note that the limit braking force may be a calculated value of signals from each sensor, and the braking force may be adjusted by adjusting the regenerative braking force and driving force of each drive motor.

Since the driving force and braking force of each drive motor are corrected in this way, the driving force and braking force of each drive motor will not exceed the limit braking force, preventing side skidding that occurs during sudden braking, and providing anti-skid function. can meet.

Next, the traction control 4j will be explained. It is applied to the electric vehicle 1 of this embodiment on a road with a small coefficient of friction such as a snowy road. The limit value of the wheel rotational acceleration is stored in advance in the storage medium of the computer 31, and the required driving force and the required wheel angular acceleration are calculated from the accelerator signal, the vehicle speed, and the limit driving force, and the wheel rotation obtained from the wheel rotation signal is calculated. Using the angular acceleration and the required wheel angular acceleration, the driving force of each drive motor can be calculated in consideration of the road surface condition.

Note that the limit driving force may be a calculated value of signals from each sensor.

Is the acceleration command from the accelerator sensor 36 limited to V? −
Even if the driving force is exceeded, the 5il calculation result will not exceed the limit value, and by restricting the transmission of the acceleration command from the accelerator sensor 36 to the drive motor, the driving force exceeding the limit value will not exceed the limit value. This prevents the wheels from rotating, suppressing slippage on snowy roads where the coefficient of friction is small, and allowing the traction control system to function on its own.

At the same time, the braking force is also detected, and the AB
By performing the eight functions simultaneously, it is possible to reliably prevent the occurrence of slips on road surfaces with a small coefficient of friction.

In this embodiment, in order to comprehensively exhibit the above functions, signal processing as shown in FIG. 6 is performed by the OgI computer 31 program.

First, the computer 31 has each wheel 2a, 2b.

3a, 3b drive motors 21a, 2lb,
22 a.

22b are manually input from the wheel rotation sensors 34 installed in each wheel rotation sensor 22b, and the vehicle speed is calculated from these signals (A).

Then, the accelerator signal from the accelerator sensor 36 installed on the accelerator pedal 11 and the brake signal from the brake sensor 37 installed on the brake pedal 12 are input, and from these accelerator signal and brake signal i
It is determined whether the l1 car is decelerating or not (B). If it is decelerating, the process proceeds to (C), and if it is constant speed or accelerating, the process proceeds to (G).

When the vehicle is decelerating and the process proceeds to (C), the required braking force and required wheel angular acceleration are calculated from the brake signal, vehicle speed, and limit braking force, and the process proceeds to (D).

In (D), each 111 obtained from each wheel rotation signal
From the wheel angular acceleration and the required wheel angular acceleration, calculate ml+power (torque) and driving force (torque) of each drive motor in consideration of the road surface condition, and proceed to (E).

Then, based on the steering signal from the steering angle sensor 35, it is determined whether the vehicle is in the 1''x rotation or not (
E), if YES, proceed to (F); if No, output is directly to the appropriate motor controller.

In (F), the required wheel angular acceleration is corrected based on the steering signal and vehicle speed by considering the cornering force caused by the vehicle's turning and comparing it with the limit braking force, and outputs the calculation result of the operation amount of each motor to each motor controller. do.

Note that (D) to (F) above correspond to the ABS function.

On the other hand, if it is determined in (B) that the vehicle is not decelerating,
Proceeding to (G), the required driving force and required wheel angular acceleration are calculated from the accelerator signal, vehicle speed, and limit driving force, and (H)
Proceed to.

In (H), the braking force and driving force of each drive motor in consideration of the road surface condition are calculated from each wheel angular acceleration obtained from each wheel rotation signal and the requested wheel angular acceleration, and the process proceeds to (J).

Note that these (G) and (H) correspond to the traction control function.

Then, based on the steering signal from the steering angle sensor 35, it is determined whether the vehicle is in the 57th turn or not (J
), in the case of YES, proceed to (K), and in the case of NO, the calculation result of the operation amount of each motor is outputted to each motor controller.

In (K), the driving force and braking force of each drive motor are calculated based on the steering signal and the differential amount of wheels on both sides from each wheel rotation signal, and a correction value (braking prevention function in 4WD) Obtain and proceed to (L).

In (L), it is determined from the vehicle speed whether the vehicle is running at a high speed or not, and if the vehicle is running at a high speed, the process proceeds to (P), and if it is not, the process proceeds to (Q).

If it is determined that you are driving at high speed at (L), (
In P), the yawing moment of the vehicle is calculated from the steering signal, each wheel rotation signal, and the vehicle speed, and correction values for each driving force that cancel this yawing moment are obtained (4WS function during high-speed driving).

On the other hand, if it is determined in (L) that the vehicle is not traveling at high speed, in (Q), the driving force difference between each driving wheel is calculated from the steering signal, each wheel rotation signal, and the vehicle speed in order to minimize the vehicle turning radius. Then, the correction value for each drive force of each drive wheel is obtained (4WS function during low speed driving).

The correction value of each driving force obtained in this way is inputted to the motor controller for each drive motor based on the calculation result, and the driving force and braking force of the wheels are appropriately adjusted.

As explained above, this embodiment is configured comprehensively as a single computer system, utilizes signals based on the running of the vehicle in multiple ways, and controls the driving force and braking force of each wheel. This is preferable from the viewpoint of the running stability of the vehicle, since the running control and attitude control of the vehicle are performed.

Furthermore, although this embodiment has been described with four functions of 4WS, 4WD, ABS, and traction control, it goes without saying that the present invention can be carried out without necessarily having four functions. do not have.

(Effects) Since the present invention is configured as described above, it is possible to completely avoid the conventional problem of distribution of driving force.
By independently controlling the drive torque and braking torque of each drive motor, it is easy to independently and freely change the circumferential speed and drive force of the drive wheels on both sides of the vehicle body.

Therefore, it is easy to implement these new technologies that involve adjusting the driving force of each wheel, and there is no need for a special mechanical configuration, and new technologies can be implemented with a relatively simple mechanical configuration. It is possible to provide an electric vehicle concept that can implement the following.

[Brief explanation of drawings]

The drawings relate to an embodiment of the present invention, and FIG. 1 is a plan view of the configuration of a drive device for an electric vehicle, FIG. 2 is a schematic structural diagram of the electric vehicle, FIG. 3 is a block diagram of a control device for the drive device, and FIG. FIG. 4 is an explanatory diagram of the 4WS function during low-speed running, FIG. 5 is an explanatory diagram of the 4WS function during high-speed running, and FIG. 6 is a flow diagram. 1; Electric car, 2 a. 2 b. Front wheel, 3 a. 3 b; Rear wheel, 1b 2 2 a. 2b drive motor,

Claims (1)

[Claims] In an electric vehicle having drive wheels on both sides of the vehicle body, each of the drive wheels is provided with a drive motor independently,
An electric vehicle characterized in that the drive torque and braking torque of these drive motors are independently controlled by signals based on the running of the vehicle.