KR20140051681A - Front and rear wheel power distribution method and apparatus - Google Patents

Abstract

The present invention relates to a method and device for distributing a driving force of front and rear wheels which improves the performance of a vehicle by determining a mode according to driver demand torque and a vehicle speed and reflecting driving features of a motor and wills of a driver. The method for distributing the driving force of the front and rear wheels of a four-wheel-drive vehicle includes a demand torque calculating step which calculates the driver demand torque based on the information of an acceleration will of the driver; a mode determining step which determines a mode for distributing the driving force of the front and rear wheels of the vehicle; a motor torque input step which calculates motor torque utilized for the front and rear wheel of the vehicle according to the determined mode then inputs the calculated motor torque to the front and rear wheels; an estimated torque calculating step which operates the motor based on the inputted motor torque and calculates the estimated torque of the motor based on a current value; and a change step which compares the calculated estimated torque and the input torque then changes the driver demand torque.

Description

TECHNICAL FIELD [0001] The present invention relates to a front and rear wheel power distribution method and apparatus,

The present invention relates to a front-rear wheel drive force distribution method and apparatus. More particularly, the present invention relates to a front-rear wheel driving force distribution method and apparatus for determining a mode according to a driver's requested torque and a vehicle speed to improve a vehicle performance by reflecting a driver's will and a driving characteristic of the motor.

An electronically controlled four-wheel drive system of a vehicle is a system that drives a vehicle only by a front wheel or a rear wheel, and distributes the engine torque to rear wheels or front wheels when a slip occurs in the drive wheels, thereby securing a driving force.

Or to secure the driving force of the vehicle in accordance with the driver's acceleration intention and steering operation.

Generally, in an electronically controlled four-wheel drive system of a vehicle, a front wheel is a main driving force, and a four-wheel drive is required, a multi-plate clutch is operated to distribute a driving force to rear wheels, and a driving force distribution amount is controlled according to a slip ratio of the clutch.

In an in-wheel motor vehicle capable of independent driving of a four-wheel drive vehicle, particularly front and rear wheels, a difference in energy consumption rate and a charging distance occurs depending on the driving force distribution.

In the in-wheel vehicle, the motor capacity, the driving range, and the reduction ratio of the front and rear wheels are different. Therefore, the motor driving efficiency according to the rotational speed and torque of the motor becomes different between the front wheel and the rear wheel during traveling of the vehicle.

This conventional four-wheel drive system is easy to secure the driving force on a hill or a road with low friction coefficient. However, the influence of the four-wheel drive system on the stability of the vehicle, There is an insignificant problem.

SUMMARY OF THE INVENTION The present invention has been conceived to solve the problems described above, and it is an object of the present invention to provide a four-wheel-drive vehicle which determines a mode according to a driver's requested torque and a vehicle speed, And a rear wheel drive force distribution method and apparatus.

A front and rear wheel driving force distribution method for achieving the above object is a method for distributing front and rear wheel driving forces of a four-wheel drive vehicle, comprising: a required torque calculation step of calculating a driver's requested torque using acceleration will information of a driver; A mode determining step of determining a front and rear wheel driving force distribution mode of the vehicle using the calculated driver requested torque information and vehicle speed information; A motor torque input step of calculating a motor torque to be used for front and rear wheels of the vehicle in accordance with the determined mode and inputting the calculated motor torque to the front and rear wheels; An estimated torque calculating step of calculating the estimated torque of the motor by driving the motor using the input motor torque and using the current value; And a changing step of comparing the calculated estimated torque with the input torque to change the driver's requested torque.

Preferably, the driving force distribution mode is at least one of an ECO mode, an ECO-Assist mode, a Power-Assist mode, and a Power mode.

Preferably, the boundary between the ECO mode, the ECO-Assist mode, the Power-Assist mode, and the Power mode is changed in consideration of at least one of the weight of the vehicle, the difference in motor capacity of the front and rear wheels, .

A front and rear wheel drive force distribution device for solving the above problems is characterized in that the front and rear wheel drive force distribution device for a four-wheel drive vehicle includes a demand torque calculation section for calculating a driver's requested torque using acceleration will information of a driver; A mode determination unit for determining a front wheel drive force distribution mode of the vehicle using the calculated driver requested torque information and vehicle speed information; A motor torque input unit for calculating a motor torque to be used for front and rear wheels of the vehicle according to the determined mode and inputting the calculated motor torque to the front wheels and the rear wheels; An estimated torque calculating unit for calculating the estimated torque of the motor by using the input motor torque to drive the motor; And a changing unit for comparing the calculated estimated torque with the input torque to change the driver's requested torque.

Preferably, the front-rear wheel drive force distribution mode is at least one of an ECO mode, an ECO-Assist mode, a Power-Assist mode, and a Power mode.

Preferably, the boundary between the ECO mode, the ECO-Assist mode, the Power-Assist mode, and the Power mode is changed in consideration of at least one of the weight of the vehicle, the difference in motor capacity of the front and rear wheels, .

The present invention can improve the one charge distance increase and the power performance due to the increase of the energy efficiency by reflecting the will of the driver in distributing the driving force to the front wheel and the rear wheel of the four wheel drive vehicle.

Further, the present invention makes it possible to quickly compensate the drive torque reduction caused by hill driving and load increase by compensating the drive input torque by comparing the drive torque with the inverter estimated torque, in accordance with the driver acceleration will.

1 is a block diagram of a front-rear wheel drive force distribution device according to a preferred embodiment of the present invention.
2 is a diagram showing an example of an efficiency torque diagram for explaining the efficiency torque.
3 is a diagram showing an example of a back torque chart for explaining a back torque curve.
4 is a diagram showing an example of a mode reference for determining a mode in the mode determination unit of the front-rear wheel drive force distribution device according to the present invention.
5 is a block diagram of a front-rear wheel driving force distribution method according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description and the accompanying drawings, substantially the same components are denoted by the same reference numerals, respectively, and redundant description will be omitted. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

In this specification, a singular form may include plural forms unless specifically stated in the phrase. It is noted that the terms "comprises" and / or "comprising" used in the specification are intended to be inclusive in a manner similar to the components, steps, operations, and / Or additions.

1 is a block diagram of a front-rear wheel drive force distribution device according to a preferred embodiment of the present invention.

1, a front and rear wheel drive force distribution device 100 according to a preferred embodiment of the present invention includes a demand torque calculation unit 110, a mode determination unit 120, a motor torque input unit 130, an estimated torque calculation unit 140 and a changing unit 150. [

The required torque calculation unit 110 calculates the driver's requested torque using the acceleration desired by the driver to accelerate the vehicle through the accelerator pedal. A known method can be used as a concrete method for calculating the driver's requested torque, which is the torque required by the driver for accelerating the vehicle, using the acceleration request information of the driver by the required torque calculating unit 110. [

The four-wheel drive vehicle or the in-wheel vehicle receives the driver's requested torque and drives the vehicle with the front wheel efficiency torque. When the front wheel efficiency torque is insufficient due to the increase of the vehicle speed or the driver's requested torque, the rear wheel efficiency torque is added, .

In a four-wheel drive vehicle or an in-wheel vehicle, the rear-wheel efficiency torque is converted into a rear-wheel torque line and the front-wheel efficiency torque is converted into a front-wheel-side torque line.

Fig. 2 is a diagram showing an example of an efficiency torque diagram for explaining the efficiency torque, and Fig. 3 is a diagram showing an example of a back torque diagram for explaining the back torque diagram.

Referring to Figs. 2 and 3, front wheel efficiency torque, rear wheel efficiency torque, front wheel torque line and rear wheel torque line will be described.

The efficiency torque is the torque at which the maximum efficiency per motor rotational speed calculated by the motor efficiency map is generated. The back torque refers to the torque per motor rotational speed at which efficiency is not taken into consideration.

That is, the front wheel efficiency torque is the motor torque line with the best efficiency according to the rotational speed of the front wheel motor, and the rear wheel torque is the motor torque line with the most efficiency according to the rotational speed of the rear wheel motor.

The front wheel torque line is a motor torque line corresponding to the rotational speed of the front wheel motor, and the rear wheel torque line is a motor torque line corresponding to the rotational speed of the rear wheel motor.

The mode determination unit 120 determines the drive distribution mode of the front wheels and the rear wheels of the vehicle based on the driver's requested torque and the vehicle speed information calculated by the required torque calculation unit 110. [

The driving distribution mode determined by the mode determination unit 120 may be determined to be one of the four divided modes.

More specifically, the mode determination unit 120 may determine a drive distribution mode of the motor in at least one of ECO mode, ECO-Assist mode, Power-Assist mode, and Power mode.

4 is a diagram showing an example of a reference of a mode for determining a mode in the mode determination unit of the front-rear wheel drive force distribution device according to the present invention.

Because of the motor torque characteristics of a four-wheel drive vehicle or an in-wheel vehicle, a maximum torque is generated at a low speed, and the torque tends to decrease from the base speed. Therefore, as the speed increases, the motor torque decreases. As the speed increases, the torque that the motor can produce decreases with the same driver's demand torque, so that the front and rear wheels move to the maximum motor torque range to meet the driver's demand torque in efficiency-driven operation.

Accordingly, an example in which the mode determination unit 120 divides the ECO mode, the ECO-Assist mode, the Power-Assist mode, and the Power mode in consideration of the driver's requested torque and the vehicle speed can be illustrated as shown in FIG.

In FIG. 4, the criterion for dividing the four modes may be changed according to the weight of the vehicle, the capacity difference of the front and rear wheels, or the reduction ratio. Basically, the mode determination unit 120 can determine the driving force distribution mode in the ECO-assist mode and the ECO mode in the low-speed region and in the ECO-Assist mode as the vehicle speed increases. In addition, the mode determination unit 120 can determine the driving force distribution mode in the Power-Assist mode when the driver's requested torque is high at a low vehicle speed and in the Power mode when the driver's requested torque and the vehicle speed are both high. Here, the driver's demand torque and the reference value of the vehicle speed, which serve as a reference for dividing each mode, can be set in advance and can be changed according to the weight of the vehicle, the capacity difference of the front and rear wheels, or the reduction ratio, as described above.

More specifically, the ECO mode is a mode determined by the mode determination unit 120 when the driver's requested torque is low and the vehicle speed is low. The ECO mode controls the front and rear wheel drive torques so that the front wheels and the rear wheels can be driven within a predetermined constant range efficiency. The front wheel motor generates the main driving force and the rear wheel motor is used as the auxiliary driving force only when the front wheel motor does not support the driver's requested torque. When the driver's requested torque occurs outside the efficiency range, the mode determination unit 120 can change the driving force distribution mode from the ECO mode to the power-assist mode.

In the ECO-Assist mode, as the vehicle speed increases, the torque that the motor can drive depends on the characteristics of the motor. Therefore, a driving torque assisting force is required to maintain the vehicle speed. The ECO-Assist mode is able to assist the insufficient torque of the front-wheel motor in consideration of efficiency by driving the rear-wheel motor in terms of the torque assist power without driving it in a constant efficiency range. The ECO-Assist mode therefore allows the rear-wheel motor to provide torque assist to a maximum torque.

In the Power-Assist mode, the front wheel motor torque is larger than that of the rear wheels. Therefore, when the driver's demand torque is high at low speed, the front wheel motor is operated from a torque point of view, not efficiency point. That is, in the power-assist mode, when the driver's requested torque exceeds the front wheel motor driving torque, the rear wheel motor assists the insufficient torque, and the rear wheel motor is driven in terms of efficiency.

In the power mode, as the driver's demand torque and vehicle speed increase, the motor drive torque is driven from the torque point of view rather than the efficiency point of view. That is, the power mode is driven by the maximum torque that the front wheel and the rear wheel can drive. Power mode is a mode that maximizes the driver's acceleration will.

That is, the four modes of the mode determination unit 120 can be described as shown in Table 1.

ECO ECO-Assist Power-Assist Power Front wheel efficiency torque Front wheel efficiency torque Front wheel torque Front wheel torque Rear wheel efficiency torque Rear wheel torque Rear wheel efficiency torque Rear wheel torque

The mode of the mode determination unit 120 may be subdivided into four or more modes.

The motor torque input unit 130 calculates the motor torque to be used for the front and rear wheels of the vehicle according to the mode determined by the mode determination unit 120 and inputs the calculated motor torque to the front and rear wheels.

The torque input from the motor torque input unit 130 drives the motor through the inverter, and the estimated torque calculation unit 140 calculates the estimated torque of the motor by the current value applied to the motor.

The changing unit 150 compares the input torque with the torque estimated by the estimated torque calculating unit 140 and reduces the driver's requested torque when the input torque contrast estimated torque value is large.

The changing unit 150 compares the torque estimated by the estimated torque calculating unit 140 with the input torque and increases the driver's requested torque when the input torque contrast estimated torque value is small so as to select the mode of the mode determining unit 120 So that the front and rear wheel torque distribution is performed again.

The front and rear wheel driving force distribution device 100 according to the preferred embodiment of the present invention is capable of reducing the motor driving torque due to the hill or load increase, Can be compensated faster than compensating depending on driver acceleration will.

The front and rear wheel driving force distribution device 100 according to the preferred embodiment of the present invention improves the one charging distance and the power performance due to the increase of the energy efficiency by reflecting the driver's intention in distributing the driving force to the front wheel and the rear wheel of the four- .

5 is a block diagram of a front-rear wheel driving force distribution method according to a preferred embodiment of the present invention.

Referring to FIG. 5, a description will be made of a front-rear wheel driving force distribution method according to a preferred embodiment of the present invention. The required torque calculation unit 110 calculates a driver's requested torque using the driver's acceleration intention information (step S510).

The mode determination unit 120 determines a driving force distribution mode using the calculated driver's requested torque information and vehicle speed information (step S520).

The motor torque input unit 130 calculates the motor torque to be used for the front and rear wheels of the vehicle according to the mode determined by the mode determination unit 120 and inputs the calculated motor torque to the front and rear wheels in step S530.

The estimated torque calculating unit 140 drives the motor using the motor torque input from the motor torque input unit 130 and calculates the estimated torque of the motor using the current value of the motor (step S540).

The changing unit 150 compares the estimated torque calculated in the estimated torque calculating unit 140 with the input torque input in the motor torque input unit 130 to change the driver's requested torque (step S550).

It should be understood that the block diagram of the front-wheel drive force distribution device 100 according to the preferred embodiment of the present invention represents exemplary conceptual aspects embodying the principles of the invention. Similarly, all of the flowcharts should be understood to represent various processes that may be substantially represented on a computer-readable medium and executed by a computer or processor, whether the computer or processor is explicitly shown.

The functions of the various elements shown in the drawings, including the functional blocks shown in a processor or similar concept, may be provided by use of dedicated hardware as well as hardware capable of executing software in connection with appropriate software. When provided by a processor, the functions may be provided by a single dedicated processor, a single shared processor, or a plurality of individual processors, some of which may be shared.

Also, the explicit use of terms such as processor, control, or similar concepts should not be interpreted exclusively as hardware capable of running software, and may be used without limitation as a digital signal processor (DSP) (ROM), random access memory (RAM), and non-volatile memory. Other hardware may also be included.

It will be apparent to those skilled in the art that various modifications, substitutions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. will be. Therefore, the embodiments disclosed in the present invention and the accompanying drawings are intended to illustrate and not to limit the technical spirit of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments and the accompanying drawings . The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (6)

A method for distributing front and rear wheel driving force of a four-wheel drive vehicle,
A required torque calculating step of calculating a driver's requested torque using acceleration will information of the driver;
A mode determining step of determining a front and rear wheel driving force distribution mode of the vehicle using the calculated driver requested torque information and vehicle speed information;
A motor torque input step of calculating a motor torque to be used for front and rear wheels of the vehicle in accordance with the determined mode and inputting the calculated motor torque to the front wheel and the rear wheel;
An estimated torque calculating step of calculating the estimated torque of the motor by driving the motor using the input motor torque and using the current value; And
And changing the driver's requested torque by comparing the calculated estimated torque with the input torque.
The method according to claim 1,
Wherein the driving force distribution mode is at least one of an ECO mode, an ECO-Assist mode, a Power-Assist mode, and a Power mode.
3. The method of claim 2,
The boundary for distinguishing the ECO mode, the ECO-Assist mode, the Power-Assist mode, and the Power mode can be changed in consideration of at least one of the weight of the vehicle, the difference in motor capacity of the front and rear wheels, To-rear drive force distribution method.
1. A front-wheel drive force distribution device for a four-wheel drive vehicle,
A required torque calculating section for calculating a driver's requested torque using acceleration will information of the driver;
A mode determination unit for determining a front wheel drive force distribution mode of the vehicle using the calculated driver requested torque information and vehicle speed information;
A motor torque input unit for calculating a motor torque to be used for front and rear wheels of the vehicle according to the determined mode and inputting the calculated motor torque to the front wheels and the rear wheels;
An estimated torque calculating unit for calculating the estimated torque of the motor by using the input motor torque to drive the motor; And
And a changing unit for comparing the calculated estimated torque with the input torque to change the driver's requested torque.
5. The method of claim 4,
Wherein the front-rear wheel drive force distribution mode is at least one of an ECO mode, an ECO-Assist mode, a Power-Assist mode, and a Power mode.
6. The method of claim 5,
The boundary for distinguishing the ECO mode, the ECO-Assist mode, the Power-Assist mode, and the Power mode can be changed in consideration of at least one of the weight of the vehicle, the difference in motor capacity of the front and rear wheels, Rear-wheel drive force distribution device.

Images