JP2906785B2 - Vehicle driving force control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for a rear wheel drive vehicle (FR vehicle) which can obtain an optimum engine driving force according to a turning state of the vehicle.

[0002]

2. Description of the Related Art When a drive slip occurs on a drive wheel,
As a conventional example of a vehicular driving force control device that performs a so-called traction control that controls so as to reduce the driving force supplied to the driving wheels in accordance with the driving slip state, for example, JP-A-58-16948, There is one disclosed in JP-A-60-56662.

In these prior arts, a drive slip state is determined by using a slip amount (slip ratio) of a drive wheel as a parameter, and a driving force supplied to the drive wheel is reduced based on the determination result to reduce the drive slip. Is to be suppressed.

[0004]

Generally, when a rear wheel drive vehicle turns, a cornering resistance _Rf as shown below is generated. In FIG. 8, for example the front and rear wheels and the vehicle schematically illustrating, front-wheel steering angle when the vehicle turns (the angle between the center line L of the front wheel and the vehicle) and theta _f, the vector of the vehicle speed V is the vehicle assuming that what occurs in the traveling direction of the center line L (shown above), a force perpendicular to the tire on the front wheel is a driven wheel, i.e. the side force SF _f occurs, the side force SF _f, the vehicle body The centripetal force = SF _f · cos θ _f which is a component perpendicular to the speed V, and the cornering resistance R _f which is a component parallel to the vehicle speed V = SF _f · sin θ _f
And Since the cornering resistance _Rf has a vector opposite to the vehicle body speed V as shown in the figure, it acts as a deceleration force on the vehicle body speed V.
The engine driving force for generating the vehicle speed V is reduced as compared with the non-turning state.

However since the conventional example was not subjected to control to compensate for the decrease in engine driving force by the cornering resistance R _f which occurs to the driven wheels as described above, as the turning state of the vehicle is strong (theta _f is Larger (larger) leads to large acceleration failure. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problem by correcting the target slip amount of the drive torque reduction control so as to compensate the engine driving force by an amount corresponding to the cornering resistance generated in the driven wheels.

[0006]

For this purpose, the vehicle driving force control apparatus of the present invention has a slip detecting means for detecting a driving slip amount of a driving wheel as shown in FIG. In the vehicle driving force control device for a rear-wheel drive vehicle, the driving torque reduction control means controls the engine driving torque to reduce the engine driving torque so as to achieve the target slip amount based on the detection result of the slip amount. Cornering resistance detecting means for detecting a cornering resistance generated in a direction parallel to the vehicle speed, and a correction amount setting for setting a correction amount for the target slip amount so as to compensate for a decrease in engine driving force due to the detected cornering resistance. Means.

[0007]

According to the present invention, during traveling of a rear wheel drive vehicle, the drive torque reduction control means achieves the target slip amount based on the drive slip amount of the drive wheel (rear wheel) detected by the slip detection means. When the control for reducing the engine drive torque is performed, the correction amount setting means, based on the cornering resistance generated in the direction parallel to the vehicle speed of the driven wheel (front wheel) during vehicle turning detected by the cornering resistance detection means, Since the correction amount with respect to the target slip amount is set so as to compensate for the decrease in the engine driving force due to the cornering resistance, it is possible to realize optimal driving force control that does not cause poor acceleration in any turning state.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows a first embodiment of the vehicle driving force control device according to the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a configuration of an embodiment, wherein 1L and 1R denote left front wheels, right front wheels, 2L and 2R denote left rear wheels, right rear wheels, and 3 denotes an engine. This vehicle is a rear-wheel drive vehicle in which rear wheels 2L and 2R, which are drive wheels, are driven by an engine 3.
Wheel rotation sensors 4, 5, 6, and 7 are provided near L, 1R, 2L, and 2R, respectively. Wheel rotation sensors 4-7
Detects the number of rotations of each wheel as a pulse signal having a frequency corresponding to the number of rotations. The obtained pulse signal having a frequency corresponding to the number of rotations VFL, VFR, VRL, VRR of each wheel is a driving force. It is input to the F / V converter 9 of the control unit 8.

The driving force control unit 8 includes an F / V converter 9 and an A / V converter 9.
The F / V converter 9 includes an A / D converter 10 and a CPU 11, and the F / V converter 9 converts the input signals from the wheel sensors 4 to 7 into a voltage and inputs the converted signals to the A / D converter 10. Converts each input signal into a digital signal and inputs it to the CPU 11. The CPU 11 uses, for example, a microcomputer.

[0010] The lateral acceleration (lateral G) sensor 14 for detecting the turning state of the vehicle is provided in this example, the lateral G signal Y _g of the lateral G sensor 14 detects and inputs to the A / D converter 10 (Note vehicle here Although the lateral G sensor is used as a means for detecting the turning state of the vehicle, a lateral slip angle sensor for detecting the lateral slip angle of the driven wheels 1L and 1R may be used instead.) Furthermore the steering angle sensor 15 for detecting a front wheel steering angle theta _f provided in this example,
Inputting a front-wheel steering angle signal theta _f the steering angle sensor 15 detects the A / D converter 10.

[0011] CPU11 each wheel rotation speed (the wheel speed) input VFL, VFR, VRL, VRR, by executing the control program of the lateral G value Y _g and based on the front-wheel steering angle theta _f FIGS. 3 and 4 Target slip amount correction control for variably controlling the correction amount for the target slip amount used when performing traction control (driving force reduction control) in accordance with the cornering resistance is performed.

That is, in the control program of FIG. 3 which is repeatedly executed by a periodic interrupt at predetermined intervals by an operation system (not shown), first, in step 10
1 in the lateral G sensor 14 from reading the lateral G value Y _g of the vehicle, makes a decision as to whether or not to correct the target slip amount in the next step 102. High lateral G of the lateral G value Y _g This determination is read in step 101 for example is equal to a predetermined value Y _g0 or (Y _g ≧ Y _g0)
In the case of cornering performed correction steps 103-105 described below, Y _g <Clear correction amount S _d0 in step 106 if the Y _g0 low lateral G turning (or running straight) (S _d0 = 0) to prevent the correction from being performed.

In step 103, the front wheel 1 is detected by the steering angle sensor 15.
L, based a steering angle theta _f of 1R reads in the front-wheel steering angle theta _f in the next step 104 determines the cornering resistance R _f by looking up the map of FIG. Here, the map of FIG. 6 shows that the cornering resistance R _f is R _f = f
₁ (θ _f ) as a function of the front wheel steering angle θ _f , and this map is stored in a memory or the like (not shown) in advance. R _f obtained in step 104
In step 105, a correction amount S _d0 for a target slip amount S _d described later is obtained by looking up the map of FIG. Here, the map shown in FIG. 7 shows that the correction amount S _d0 is _{calculated based on the} cornering resistance R by S _d0 = f ₂ (R _f ).
This map is represented as a function of _f , and this map is stored in a memory or the like (not shown) in advance. After the execution of the control program in FIG. 3, the control program for setting the correction amount of the target slip amount in FIG. 4 is subsequently executed.

In the control program shown in FIG.
Target slip amount S in step 111_dMake the settings for This goal
Slip amount S_dIs set, for example, by setting the vehicle speed V as a parameter
(Note that the target
Lip amount S_dIs the slip rate). Next Step 11
In step 2, the correction amount S obtained in step 105 described above is used._d0The above
Target slip amount S_d(S_d= S_d+ S_d0)thing
The target slip amount S_dIs corrected. Note that FIG.
If it is determined that no correction is made in
The correction amount S_d0Becomes zero, so step 112
Even if you execute _dDoes not change. Sought in this way
Target slip ratio S_dIn step 113 using
Control (engine driving force reduction control)
You.

FIG. 5 shows a control program corresponding to the traction control in step 113. In this embodiment, a program for cutting off the fuel supply to each of the cylinders 13-1 to 13-6 of the engine 3 is used. That is, first, in step 121 of FIG. 5, the rotational speeds VFL, V
FR and rotation speeds VRL, VR of left and right rear wheels as drive wheels
R is read from the corresponding wheel rotation sensors 4 to 7, respectively.
In step 122, the average rotational speeds VF, VR of the front wheels and the rear wheels
VF = (VFL + VFR) / 2, VR = (VRL + V
RR) / 2, and in the next step 123, the slip ratio S is calculated by S = (VR-VF) / VR. Performing S ≧ S _d determination of whether or not at step 124 using the target slip ratio S _d obtained in the slip ratio S and the step 112. If YES in S ≧ S _d In this determination, it is determined that the driving slip amount is larger than the target slip amount, a step for suppressing the drive slip
At 125, a fuel cut signal FC is output from the CPU 11 to the fuel supply control unit 12. In response to this signal FC, the fuel supply control unit 12 sends a signal to each cylinder of the engine 3.
The injection pulse IP output to each of 13-1 to 13-6 is cut off, and fuel cut is performed. On the other hand, if S < _Sd is NO in the determination of step 124, it is determined that the drive slip amount has become smaller than the target slip amount and the drive slip has been eliminated, and in step 126, a normal fuel cut is not performed. Perform driving force control.

The output of the fuel cut signal FC is
For example, by executing a control program (not shown), the number of cylinders (for example, 3/6 cylinder cut → 6/6) for which fuel supply is cut off according to the drive slip amount (in this case, the slip ratio S)
Cylinder cut or 2/6 cylinder cut → 4/6 cylinder cut → 6 /
6 cylinder cut pattern is typical), and at the same time, the cylinder arrangement for actually cutting the fuel supply and the timing of the fuel cut are determined based on the pattern. In the case of the cylinder cut, three cylinders among the cylinders 13-1 to 13-6 are cut evenly during the fuel supply cut.

The operation of the above control will be described with reference to FIG.
FIG. 8 schematically shows the front wheels, the rear wheels, and the vehicle. In the turning state where the front wheel steering angle = θ _f (rear wheel = neutral), the vector of the vehicle speed V moves in the traveling direction on the center line L of the vehicle (shown in FIG. The description will be expanded assuming that the above occurs. Here, when the side force SF _f generated in the front wheels, side force SF _f deceleration force is a component F consisting perpendicular centripetal force on the vehicle body speed V, a component parallel to the vehicle speed V relative to the vehicle speed V (Cornering resistance) R _f , where F = SF _f · cos θ _f and R _f = SF _f · sin θ _f
Become (Note front wheel side slip angle is small enough in comparison with the front-wheel steering angle theta _f can be regarded 0 and, the two equations do not take into account the side slip angle of the front wheels).

The cornering resistance R _f can be expressed as R _f = F · tan θ _f , as is apparent from FIG. Here, the force F perpendicular to the vehicle speed V is F = M _f ·
Y _g (provided that M _f: front wheel mass, Y _g: lateral acceleration), and since the F and tan theta _f increases both as the time Koyoko G turning, even cornering resistance R _f as when high lateral G turning large In the end, the function f _{1 of} θ _f is shown in the map of FIG.
(Θ _f ). Therefore, step 104 in FIG. 3 for obtaining the cornering resistance _Rf functions as a cornering resistance detecting means.

The above-mentioned cornering resistance R_fIs engine driven
Acts to reduce force, preventing poor acceleration.
To compensate for this decrease in engine drive power.
More specifically, the target scan used for engine drive power reduction control
Rip rate S_dShould be increased. Therefore, in FIG.
R_fFunction f_Two(R_f), S _d
Correction amount S for_d0The step 105 in FIG.
It will function as an amount setting means.

Using the correction amount S _d0 , step 11 in FIG.
The target slip amount (target slip ratio) S _d corrected in 2
Since that is acquired by compensating for the decrease by R _f of the engine driving force, the engine drive force reduction control in step 113 using the S _d (i.e. step 121 to 126 in FIG. 5), also acceleration during turning Optimal engine driving force control to be ensured can be performed.

In the above embodiment, the engine driving force reduction control by fuel cut is employed. However, the present invention is not limited to this. For example, a throttle opening control for electrically controlling the throttle valve of the engine, Control of ignition timing of the engine or brake control for directly applying pressure to the wheel cylinder may be used. Further, step 11 in FIG.
The target slip amount set in 1 may be variably controlled according to the turning state in order to secure running stability during turning.

[0022]

As described above, the vehicle driving force control apparatus of the present invention corrects the target slip amount of the driving torque reduction control so as to compensate the engine driving force by an amount corresponding to the cornering resistance generated in the driven wheels. Thus, it is possible to realize optimal driving force control that does not cause poor acceleration in any turning state.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of the present invention.

FIG. 2 is a diagram showing a configuration of a first embodiment of a vehicle driving force control device of the present invention.

FIG. 3 is a flowchart showing a control program of a CPU in the example.

FIG. 4 is a flowchart showing a control program of a CPU in the same example.

FIG. 5 is a flowchart showing a control program of a CPU in the same example.

FIG. 6 is a diagram illustrating a map of a cornering resistance used in the example.

FIG. 7 is a diagram illustrating a map of a correction amount with respect to a target slip amount used in the example.

FIG. 8 is a schematic diagram of a vehicle for explaining the operation of the example.

[Explanation of symbols]

 1L, 1R Front wheel (driven wheel) 2L, 2R Rear wheel (drive wheel) 3 Engine 4-7 Wheel rotation sensor 11 CPU 12 Fuel supply control unit 13-1-13-6 Cylinder 14 Lateral G sensor 15 Steering angle sensor

Claims (1)

(57) [Claims] 1. A system comprising: a slip detecting means for detecting a driving slip amount of a driving wheel; and a driving torque reduction control means for reducing an engine driving torque based on a detection result of the driving slip amount so as to achieve a target slip amount. A driving force control device for a rear-wheel drive vehicle, wherein a cornering resistance detecting means for detecting a cornering resistance generated in a direction parallel to a vehicle speed of a driven wheel during turning of the vehicle; A driving amount control device for a vehicle, comprising: a correction amount setting means for setting a correction amount for the target slip amount so as to compensate for a decrease in engine driving force.