JPS63207730A - Differential control device - Google Patents

Abstract

PURPOSE:To improve a turning performance by comparing the detected value of the difference in rotating speed between right and left wheels with the threshold of the rotating speed difference with respect to a vehicle speed, and controlling so as to operate a differential limiting mechanism when the detected valve of the rotating speed difference is larger than the threshold. CONSTITUTION:A vehicle speed detecting means 14 for detecting vehicle speed and rotating speed detecting means 16, 18 for detecting the rotating speeds of right and left driving wheels are provided in a differential control device 10 for controlling the differential movement of a differential device having a differential limiting mechanism 12. The output signals of the detecting means 14, 16, 18 are inputted into a controller 20, which operates the difference in rotating speeds between right and left driving wheels while obtaining the threshold value of the rotating speed difference corresponding to vehicle speed by a map. And, the operated rotating speed difference is compared with the threshold and, when the former is larger than the latter, a current controlling pressure- reducing valve 30 which forms an operating means 22 for the differential limiting mechanism 12 is controlled so as to limit the differential movement of the differential device.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a differential control device, and more particularly, to a device for controlling the differential of a differential device equipped with a differential limiting mechanism and installed in a vehicle. .

(Prior art) In a differential device equipped with a differential limiting mechanism built into a vehicle, when the difference in rotation speed between left and right drive wheels exceeds a reference value, the differential of the differential device is limited and one drive wheel is Are the wheels on soft ground or other low ground? ! A device has been proposed that compensates for the reduction in driving force caused by entering a road surface with an OX coefficient (
(Japanese Patent Application Laid-open No. 133920/1983).

(Problems to be Solved by the Invention) In the device according to the above proposal, when the vehicle turns at an angle greater than a certain angle, the differential is not locked. Care has been taken to ensure that there are no hindrances.

However, even when turning at the same radius at an angle less than a certain angle, as the vehicle speed increases, the difference in rotation speed between the left and right wheels increases and exceeds the fixed reference value. Become. As a result, the differential of the differential is limited,
Turning performance deteriorates.

An object of the present invention is to provide a differential control device that can improve turning performance by changing a reference value depending on vehicle speed.

(Means for solving interlayer points) The present invention is a device for controlling the differential of a differential gear having a differential limiting mechanism, which includes means for detecting vehicle speed and detecting the rotation speed of the left wheel. a means for detecting the rotational speed of the right wheel; and a controller receiving signals from these means, which calculates the rotational speed difference between the left and right wheels and determines a threshold value of the rotational speed difference corresponding to the vehicle speed. , a controller that compares the threshold value with the calculated rotational speed difference, and a means for operating the differential limiting mechanism, which limits the differential of the differential limiting mechanism when the calculated rotational speed difference is larger than the threshold value. and an operating means controlled by the controller to do so.

In a preferred embodiment, the controller is a CPU, and the relationship between the vehicle speed and the rotation speed difference threshold is stored in the controller as a map. In this map, the threshold value of the rotational speed difference tends to increase as the vehicle speed increases.

(Operations and Effects) The controller calculates the rotation speed difference between the left and right wheels, and at the same time calculates the rotation speed difference threshold corresponding to the vehicle speed from the map.

Then, the calculated rotational speed difference is compared with a threshold value, and when the former is larger than the latter, the operating means is controlled to limit the differential.

If the threshold value is selected so that as the vehicle speed increases, the threshold value that should serve as the standard for the difference in rotation speed between the left and right wheels increases, and as the vehicle speed increases, the threshold value also increases, and as a result, the differential of the differential gear is reduced. The differential can now be limited only when it is necessary, improving turning performance.

(Embodiment) As shown in FIG. 1, the differential control device IO controls the differential of a differential device having a differential limiting mechanism 12, and includes means 14 for detecting vehicle speed and a left It includes means 16 for detecting the number of rotations of the drive wheel, means 18 for detecting the number of rotations of the right drive wheel, a controller 20, and an operating means 22.

As the differential device, a known device including a differential limiting mechanism can be used. A differential limiting mechanism generally includes a plurality of friction plates, and differential movement is limited by bringing these friction plates into contact with each other using a hydraulic device. Furthermore, by releasing the hydraulic pressure, the restriction on differential movement is canceled and the differential device can freely differentially move.

The means 14 for detecting the vehicle speed, the means 16 for detecting the rotation speed of the left drive wheel and the means 18 for detecting the rotation speed of the right drive wheel are tachometers or other detectors known per se.

The controller 20 is a CPU or a computer, and receives signals from the vehicle speed detection means t4, the left rotation speed detection means 16, and the right rotation speed detection means 18, performs calculations and comparisons to be described later, and controls the operation means 22. do.

In the illustrated embodiment, the operating means 22 comprises a liquid pump 24, an unload relief valve 26, an accumulator 28, a current-controlled pressure reducing valve 30, and a check valve 32.

A tube 34 is connected to pump 24 and differential limiting mechanism 12 . The unload relief valve 26 is installed in the pipe 34 , and the current-controlled pressure reducing valve 30 is installed in the portion leading from the unload relief valve 26 to the differential limiting mechanism 12 . Further, an accumulator 28 is connected between the unload relief valve 26 and the current-controlled pressure reducing valve 30, and a check valve 32 is installed between the unload relief valve 26 and the accumulator 28. Check valve 32 only allows liquid flow or pressure transfer from unload relief valve 26 to accumulator 28 .

When pressure fluid is supplied from the pump 24, the unload seat of the unload relief valve 26 is closed, and the check valve 32 is closed.
opens. As a result, pressurized fluid from pump 24 is directed via tube 34 to accumulator 28, where the fluid pressure increases. The pressure in the accumulator 28 is increased by the unload relief valve 2.
When the adjusted pressure of 6 is reached, the unload relief valve 26 opens instantly and the pressure liquid from the pump 24 is transferred to the reservoir tank 3.
6, and the check l#32 closes. Thus, a constant pressure is stored in the accumulator 28.

The current-controlled pressure reducing valve 30 is equipped with a DC solenoid in its pilot section, and controls the pressure continuously and steplessly by controlling the input current to this solenoid (il+lJ). The control pressure in this case is then substantially proportional to the input terminal. So, by the controller 20? J, if the current given to the flow control pressure reducing valve 30 is controlled,
You can get the right amount of pressure.

The controller 20 makes a determination as shown in FIG. 2, for example, and controls the operating means 2z. After initialization (40) L/, read the vehicle speed U (42), read the rotation speed ω of the left middle wheel (44), and read the rotation speed ω2 of the right wheel (46).
). Then, calculate the absolute value Δω of the left and right rotational speed difference (
48).

The controller 20 stores a map 50 that is a graph of the relationship between the vehicle speed U and the rotational speed difference threshold value ω◇. As shown in detail in FIG. 3, the map 50 is drawn as a graph in which the threshold value ω0 tends to increase proportionally as the vehicle speed U increases. The trend of the graph can be determined experimentally or empirically.

After calculating the left and right rotational speed difference Δω, the controller 20 calculates the threshold value ω0 corresponding to the 4L speed U from the map 50 (
52), compare the calculated rotational speed difference Δω with the threshold value ω0 (
54).

When the calculated rotational speed difference Δω is larger than the threshold value ω0, the controller 20 controls the operating means 22 to limit the differential of the differential limiting mechanism 12. The operation of the differential limiting mechanism 12 by the operating means 22 limits the differential of the differential M1 limiter 12 or cancels the limitation of the differential, so to speak.
-OFF may also be used, but in the illustrated embodiment, since the operating means 22 is provided with a current-controlled pressure reducing valve 30, the controller 20 is configured to change the differential limiting amount according to the vehicle speed υ. ,Control.

A graph obtained by experimentally or empirically determining the pressure P to be applied to the differential limiting mechanism 12 depending on the magnitude of the vehicle speed U,
A graph showing the relationship between the pressure P to be output by the current control pressure reducing valve 30 and the current i is stored in advance as a map in the controller 20, and the pressure P corresponding to the vehicle speed U is determined from the map to obtain the pressure P. Find the current i (56)
.

Then, the current i is output to the current-controlled pressure reducing valve 30 of the operating means 22 (58). As a result, the differential limiting mechanism 12 limits the differential depending on the vehicle speed.

When the calculated rotational speed difference Δω is less than or equal to the threshold value ω◇, the controller 20 decides to release the restriction on the differential of the differential limiting mechanism 12 (60) and applies zero current to the current-controlled pressure reducing valve 30 of the operating means 22. Output (58).

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the differential control device, FIG. 2 is a control flowchart, and FIG. 3 is a graph showing the correlation between the vehicle speed and the rotation speed difference threshold stored in the controller as a map. 10: differential control device, 12: differential limiting mechanism, I4: vehicle speed detection means. 16: Left rotation speed detection means, 18: Right rotation speed detection means, 20: Controller, 22: Operation means, 30: Current-controlled pressure reducing valve. Agent Patent Attorney Nobuyuki Matsunaga Figure 1 Figure 2

Claims (1)

[Claims] A device for controlling the differential of a differential gear having a differential limiting mechanism, comprising means for detecting vehicle speed, means for detecting the number of revolutions of a left wheel, and means for detecting the number of revolutions of a right wheel. ,
A controller that receives signals from these means and calculates the rotation speed difference between the left and right wheels, determines a threshold value for the rotation speed difference corresponding to the vehicle speed, and compares the threshold value with the calculated rotation speed difference; means for operating the differential limiting mechanism, the operating unit being controlled by the controller to limit the differential of the differential limiting mechanism when the calculated rotational speed difference is greater than the threshold; dynamic control device.