JPH01275225A - Differential limiting torque control device - Google Patents

Abstract

PURPOSE:To aim at enhancing the control accuracy by setting a differential rotational speed which is produced when a differential limiting torque is given in accordance with a running condition, as a desired value, and by controlling the value of differential limiting torque so as to make a detected value of a differential rotational speed coincident with the desire value. CONSTITUTION:A differential limiting torque control means 4 controls the fastening force of a differential limiting clutch 1 so as to change the differential limiting torque between drive wheels 2, 3 of front and rear or lift and right. In this arrangement, a means 5 detects a running condition of a vehicle, and a means 6 detects a differential rotational speed between drive wheels. Further, the control means 4 sets a differential rotational speed which is produced when a differential limiting torque is given in accordance with a running condition, as a desired value, and obtains a desired differential rotational speed value upon running in accordance with a detected value of the running condition. Thereafter, the value of the differential limiting torque is controlled so as to make a detected value of the differential rotational speed coincident with the desired differential rotational speed value.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a differential limiting torque system that variably controls the differential limiting torque between left and right or front and rear drive wheels by externally controlling the clamping force. Regarding a control device.

(Prior Art) Conventionally, a differential limiting torque control device uses a hydraulic clutch as a differential limiting clutch, and the clutch engagement pressure is variably controlled by an external hydraulic control means, thereby establishing a proportional relationship with the clutch engagement pressure. A device for controlling differential limiting torque is known in
6, JP-A-62-103227, etc.).

(Problem to be Solved by the Invention) However, in such a conventional differential limiting torque control device, the driving state of the vehicle (for example, turning radius, lateral acceleration, etc.) is ) was set as a target value for the differential limiting torque corresponding to If there are variations or changes in characteristics of control output system members such as a limiting clutch, the differential limiting torque actually generated by the differential limiting clutch will also vary or change in accordance with the variations or changes, and the differential will always be constant. There was a problem in that the limit torque could not be controlled and the control accuracy decreased.

Note that variations in control output system members refer to variations due to the parts themselves or their assembly, and changes in characteristics refer to changes in the characteristics of the differential limiting torque relative to the clutch engagement pressure of the differential limiting clutch due to changes over time, oil deterioration, etc. This refers to changes in the clutch engagement pressure characteristics with respect to the current value to the hydraulic control valve.

(Means for Solving the Problems) The present invention aims to solve the above-mentioned problems, that is, to set the differential rotation speed that can occur when differential limiting torque is applied depending on the running condition as a target value. By setting the differential rotation speed target value and controlling the increase/decrease of the differential limit torque so that the detected value of the differential rotation speed that actually occurs matches the differential rotation speed target value, the control accuracy of the differential limit torque can be improved. The purpose of this invention was to provide a differential limiting torque control device.

In order to achieve the above-mentioned object, the differential limiting torque control device of the present invention, as shown in the conceptual diagram of the claim in FIG. In a vehicle equipped with a differential limiting torque control means 4 capable of variably controlling differential limiting torque of the driving wheels 2, a driving state detecting means 5 detecting the driving state of the vehicle, and a driving state detecting means 5 for detecting the driving state of the vehicle;
. The rotational speed is set as a target value, a differential rotational speed target value is determined during driving based on the driving state detection value obtained from the driving state detection means 5, and the difference obtained from the differential rotational speed detection means 6 is determined. The present invention is characterized in that the differential rotation speed detection value is controlled to increase or decrease the differential limiting torque in a direction that makes the detected value of the differential rotation speed coincide with the differential rotation speed target value.

(Function) When the vehicle is running, the differential limiting torque control means 4 determines the differential rotation speed target value for that running state based on the running state detection value from the running state detection means 5 and a preset target value. is determined, and the differential rotation speed detection value obtained from the differential rotation speed detection means 6 is made to match the differential rotation speed target value, that is, when the detected value is larger than the target value, the differential limiting torque is On the other hand, if the detected value is smaller than the target value, increase/decrease control is performed to decrease the differential limiting torque.

Therefore, control is performed in which the differential rotation speed actually generated is taken in as feedback information with respect to the target value, so the hydraulic control valve between the control unit that outputs the differential limiting torque control command and the drive wheels is performed. This eliminates the influence of control output system members such as the control output system members and differential limiting clutches, and regardless of variations in the control output system members or changes in characteristics, a constant control accuracy of the differential limiting torque is always ensured, and the desired differential limiting performance can be obtained.

(Example) Embodiments of the present invention will be described below based on the drawings.

First, the configuration will be explained.

As shown in FIG. 2, the rear wheel drive vehicle to which the differential limiting torque control device of the embodiment is applied includes an engine 10, a transmission 11, a propeller shaft 12, a differential 13, drive shafts 14, 15, rear wheels 16, 1
γ, and has a front wheel of 18°19.

The left and right rear wheels 16.
Differential limit torque control that variably controls the differential limit torque of No. 7 applies pressurized oil from an external hydraulic source 30 to hydraulic control valve 3.
This is done by setting the clutch engagement pressure ΔP to a predetermined value through the clutch clutch 1 and guiding it to the differential limiting clutch 20.

A predetermined differential limiting command current value ■ to the hydraulic control valve 31
The controller 32 that outputs the memory circuit (RAM, R
This controller 32 includes a vehicle speed sensor 33
and detection signals from the lateral acceleration sensor 34, right rear wheel speed sensor 35, and left rear wheel speed sensor 36, YCI, NRR,
NRL is input.

Next, the effect will be explained.

First, the flow of the differential limiting control operation in the controller 32 will be described based on the flowchart shown in FIG.

At step 100, vehicle speed V and lateral acceleration Y9 are read.

In step 101, a turning radius R is calculated based on the vehicle speed V and the lateral acceleration Y9.

The calculation formula is as follows.

R=V'/Y9 In step 102, the turning radius R, the lateral acceleration Y9, and the preset differential rotation speed target value map (Fig. 4)
Accordingly, the differential rotation speed target value ΔN IJAP is calculated.

Note that the differential rotation speed target value ΔN shown in the differential rotation speed target value map in FIG. This is the value that occurs when driving with the optimum value (approximately 01). Based on the differential rotation speed characteristics with respect to the turning radius R, correction is made so that the value of the differential rotation speed becomes smaller when the lateral acceleration Y9 is large. Adding.

In step 103, the right rear wheel speed NRR and the left rear wheel speed NRL are determined.
is loaded.

In step +04, the right rear wheel speed NRR and the left rear wheel speed N
A differential rotation speed detection value ΔNREAL is calculated from RL.

The calculation formula for ΔNnEAL is as follows.

ΔN REAL=l N RR - N RL + At step 105, the differential rotation speed detection value ΔNREAL and the differential rotation speed target value ΔN are compared.

Then, when ΔNII, >ΔN, , AP, the process proceeds from step 105 to step 106, and the differential limiting command current value (■) output to the hydraulic control valve 31 is increased.

Further, when ΔNnEAL=ΔN1jAP, the process proceeds from step 105 to step 107, and the hydraulic control valve 31
The differential limit command current value I output to is held.

Further, when ΔNIIEAL<ΔNLIAr', the process proceeds from step 105 to step 108, and the differential limiting command current value (■) output to the hydraulic control valve 31 is decreased.

Next, the operation during driving will be explained.

When the vehicle is running, the differential limit command current value (■) in steps 106 to 108, which are the output steps, is determined based on the comparison between the differential rotation speed detection value ΔN0 and the differential rotation speed target value ΔN. °increase′°゛maintain′.

``' One of the following actions is performed.

Due to this output operation, the differential limiting torque is controlled so that the differential rotational speed detection value △NREAI matches the differential rotational speed target value △N. , the content of the control is such that the drive slip ratio converges to the optimum value (approximately 0.1), as shown in the differential rotation speed target value map in FIG.

Therefore, if one wheel slips on a split μ road or inner wheel spin occurs during a sharp turn on a dry road, the differential rotation speed detection value △NREAL increases, causing △NREA to increase.
The relationship is I->ΔN, and by increasing the command current value (■) in step 106, the differential limiting torque is strengthened, and one-wheel slip, inner-wheel spin, etc. are suppressed.

In addition, under driving conditions where tight corner play kink occurs, the actual differential rotation speed detection value ΔNI+ or - or the differential rotation speed target value ΔNi will not be reached, and ΔN REAL
<ΔNIJAP is established, and the differential limiting torque is weakened by decreasing the command current value in step 108, and tight corner play kink is effectively suppressed.

Furthermore, when turning, the higher the lateral acceleration Y9, the higher the differential rotation speed target value ΔN.
Since the relationship NREAL>ΔN often occurs, the higher the lateral acceleration Y9 is, the higher the differential limiting torque will be, making it possible to obtain sufficient driving torque during turns and also enable power sliding. .

As explained above, in the differential limiting torque control device of the embodiment, the effects described below can be obtained.

■ Set the differential rotation speed detection value ΔN REAL, which is the differential rotation speed actually occurring, to the differential rotation speed target value ΔN.

Since the control is performed by taking in as feedback information, the hydraulic control valve 31 and the differential limiting clutch 20 between the controller 32 that outputs the command current value (■) of the differential limiting torque and the left and right rear wheels 16° 17 are controlled. The influence of the control output system components is eliminated, and regardless of variations or changes in characteristics of the control output system components, constant differential limiting torque control accuracy is always ensured, and as mentioned above, the desired difference can be achieved. It is possible to obtain motion-limited performance.

■ When setting the differential rotation speed target value map shown in Figure 4, the differential rotation speed target value map was set including the control details of the differential limit torque, so the differential rotation speed target value map was set separately. The differential limiting torque can be controlled by a processing operation with a small storage capacity and a small number of processing steps.

Although the embodiments have been described above based on the drawings, the specific configuration is not limited to these embodiments, and the present invention includes any changes that do not depart from the gist of the present invention.

For example, in the embodiment, an example is shown in which the differential is limited between the left and right drive wheels, but the present invention can also be applied to a differential limiting device that limits the differential between the front and rear wheels. In this case, the differential rotation speed is defined as the difference in rotation speed between the front and rear wheels.

Further, in the embodiment, an example was shown in which the vehicle running state is obtained using a lateral acceleration sensor and a vehicle speed sensor, but a steering angle sensor, a yaw rate sensor, etc. may also be used. Although an example of control using the turning radius R and centripetal acceleration Y9 has been shown, the specific control content is not limited to the embodiment.

In addition, in the example, since the differential rotation speed target value map was set including the control details of the differential limit torque, the differential rotation speed target value is determined according to the driving condition and the increase/decrease control of the differential limit torque is controlled. We have shown an example of how to do this, but by setting the differential limit torque target value characteristic map for the driving condition and the differential rotation speed target value characteristic map for the differential limit torque in advance, The differential limiting torque target value is determined based on the differential limiting torque target value characteristic map, and the differential rotation speed that can occur when this differential limiting torque target value is given is calculated based on the differential rotation speed target value characteristic map. It may be an example in which a numerical target value is determined and control is performed to increase or decrease the differential limiting torque target value in a direction to make the differential rotation speed detection value coincide with the differential rotation speed target value.

(Effects of the Invention) As explained above, in the differential limiting torque control device of the present invention, the differential limiting torque control means is configured to control the differential limiting torque generated when differential limiting torque is applied depending on the running condition. The differential rotation speed to be obtained is set as a target value, and the differential rotation speed target value is determined during driving based on the driving condition detection value obtained from the driving condition detection means, and the differential rotation speed target value is obtained from the differential rotation speed detection means. Since the means is used to increase/decrease the differential limiting torque in the direction of making the differential rotational speed detection value match the differential rotational speed target value, the control unit that outputs the differential limiting torque control command and the drive wheels are This creates a feedback control system that eliminates the influence of control output system members such as hydraulic control valves and differential limiting clutches between The control accuracy of dynamic limiting torque is ensured, and the effect that desired differential limiting performance can be obtained is obtained.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of a claim showing the differential limiting torque control device of the present invention, Fig. 2 is an overall view showing a rear wheel drive vehicle to which the differential limiting torque control device of the embodiment is applied, and Fig. 3 is an implementation diagram. FIG. 4, which is a flowchart showing the flow of differential limiting operation in the example controller, is a differential rotation speed target value map with respect to turning radius and lateral acceleration. 1...Differential opening clutch 2.3...Drive wheel 4...Differential limiting torque control means 5...Running state detection means 6...Differential rotation speed detection means

Claims (1)

[Scope of Claims] 1) A vehicle equipped with a differential limiting torque control means capable of variably controlling the differential limiting torque between left and right or front and rear drive wheels by controlling the engagement force of a differential limiting clutch, comprising: A driving condition detection means for detecting a driving state and a differential rotation speed detection means for detecting a differential rotation speed of the drive wheels are provided, and the differential limiting torque control means controls the differential limiting torque according to the driving condition. The differential rotation speed that can be generated when the differential rotation speed 1. A differential limiting torque control device, characterized in that said differential limiting torque is controlled to increase or decrease in a direction in which a differential rotational speed detection value obtained from a differential rotational speed detection means coincides with said differential rotational speed target value.