JPS62110531A - Differential limiting clutch pressure controller for vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is used in differentials that distribute driving force between left and right wheels, center differentials of four-wheel drive vehicles that distribute driving force between front and rear wheels, etc. The present invention relates to a differential limiting clutch pressure control device for a vehicle that applies a clutch engagement force to a wet friction clutch means, which is a limiting means, using external fluid pressure.

(Prior Art) As a differential device equipped with a conventional differential limiting means, for example, the one described in "Complete Book of Automotive Engineering, Volume 9, Power Transmission Device" (November 15, 1980 ■Sankaido Publishing), pages 321 to 321 3
Devices such as those described on page 24 are known.

In this conventional device, a wet multi-disc friction clutch provided between the differential case and the side gear is used as the differential limiting means. The thrust force generated by the cam mechanism is used as clutch engagement force, and this clutch engagement force generates differential limiting torque.

It was a device equipped with so-called torque proportional differential limiting means.

Note that the differential limiting means here refers to a means for exerting a differential limiting function, and a device usually referred to as a limited slip differential is distinguished from the other as a differential device with a built-in differential limiting device. When simply written as a differential device (differential means), it refers to an ordinary differential device (conventional differential) that does not have a limiting function.

(Problems to be Solved by the Invention) However, in such conventional devices, a wet multi-disc friction clutch was used as the differential limiting means, so this wet multi-disc friction clutch was When the oil temperature of the cooling oil filled in the friction clutch increases due to frictional heat, such as when driving for a long time in the engaged or engaged state, the clutch friction coefficient decreases as the oil temperature increases, and at the same time There was a problem in that the differential limiting torque also decreased, and the differential limiting torque changed due to changes in oil temperature.

In other words, although the friction coefficient characteristics of a wet multi-disc friction clutch depend somewhat on the material and number of clutch plates, in general, as shown in Figure 9, when the engagement pressure is constant, the oil temperature t is large. The friction coefficient W decreases as the surface becomes more slippery.

The differential limiting torque T obtained by engaging the wet multi-disc friction clutch is: TOCP-g・n-r-A n; number of clutches r; clutch average radius A: pressure receiving area; therefore, the differential limiting torque characteristic is is as shown in FIG. 10, and if the oil temperature (t+<t2) is different, the differential limiting torque T will also be different.

Therefore, even if the same engagement pressure P is applied to the wet multi-disc friction clutch, the differential limiting torque gradually decreases due to the increase in oil temperature, and a sufficient differential limiting effect may not be exhibited.

Additionally, instead of using a cam mechanism, a device that applies clutch engagement pressure to a friction clutch using fluid pressure from the outside (Japanese Unexamined Patent Publication Nos. 53-45832 and 1989-199331) etc.) becomes especially noticeable when clutch engagement pressure is applied for a long time,
Even if the same fluid pressure is applied to the wet friction clutch, the desired differential limiting torque may not be obtained due to changes in the oil temperature E.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above-mentioned problems, and in order to achieve this purpose, the present invention has adopted the following solving means. .

The solution of the present invention will be described with reference to the conceptual diagram of the claim shown in FIG. A wet friction clutch means 4 is provided between the drive input part and the drive output part of the drive means 3 and makes the differential limiting torque variable by control fluid pressure, and a fluid pressure generating means connected to the wet friction clutch means 4. means 5 and an actuator 6 for controlling the fluid pressure from the fluid pressure generating means 5.

In the differential limiting clutch pressure control device for a vehicle, comprising: a control means 8 for outputting a control signal for controlling fluid pressure based on an input signal from a predetermined input sensor; 4 includes an oil temperature sensor 701 that detects the oil temperature of the clutch engagement part 4, and the control means 8 corrects the fluid pressure to the wet friction clutch means 4 in a direction in which the differential limiting torque does not change in response to changes in oil temperature. It was used as a means to do so.

(Function) Therefore, in the vehicle differential limiting clutch pressure control device of the present invention, as described above, the fluid pressure to the wet friction clutch means is corrected in a direction in which the differential limiting torque does not change in response to changes in oil temperature. By using this means, changes in the friction coefficient of the friction clutch due to changes in oil temperature are corrected, and differential limiting torque corresponding to changes in oil temperature can be obtained.

Furthermore, even in cases where differential limiting is controlled in accordance with driving conditions, driving operations, etc., a desired differential limiting torque can be obtained by using it for correction control of output fluid pressure.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In describing this embodiment, an automobile differential limiting clutch pressure control device equipped with a wet multi-disc friction clutch means operated by external hydraulic pressure will be taken as an example.

First, the configuration of the embodiment will be explained.

As shown in FIGS. 2 to 4, the embodiment device has a differential bag @
(Differential means) 10, wet multi-disc friction clutch means (wet friction clutch means) 11, hydraulic pressure generator (fluid pressure generation means) 12. It is equipped with a control unit (control means) 13 and an input sensor 14, and each configuration will be described below.

The differential bag 3110 has a differential function that provides a speed difference between the left and right wheels according to the rotational speed difference in a driving state where a rotational speed difference occurs between the left and right wheels, and a differential function that equalizes the engine driving force to the left and right driving wheels. This is a device that has a driving force distribution function that distributes and transmits the driving force.

This differential device 10 is housed in a housing 16 that is attached to the vehicle body by a stud port 15, and includes a ring gear 17, a differential case 18,
It includes a pinion mate shaft 19, a differential pinion 20, and side gears 21 and 21'.

The differential case 18 includes a housing 16
It is rotatably supported by tapered roller bearings 22°22'.

The ring gear 17 is connected to a differential case 18.
The propeller shaft 23 is fixed to the propeller shaft 23 and meshes with a drive pinion 24 provided on the propeller shaft 23, from which rotational driving force is input.

The side gears 21, 21' include a left wheel drive shaft 25 and a right wheel drive shaft 2, which are drive output shafts.
6 is provided for each.

The wet multi-plate friction clutch means 11 includes the differential bags J and l.
This means is provided between the drive input part and the drive output part of Q, and is applied with clutch engagement force by external hydraulic pressure to generate differential limiting torque.

This wet type multi-plate friction clutch means 11 includes a housing 16
And the items housed in the differential case 18 include a wet multi-plate friction clutch 27.27', a pressure ring 28.28', a reaction plate 29.29', a thrust bearing 30.30', a spacer 31.31', Push port/end 32, hydraulic piston 33. It is equipped with an oil chamber 34 and a hydraulic boat 35.

The wet multi-plate friction clutch 27, 27' has friction plates 27a, 27'a fixed in the rotational direction to the differential case (drive input part) 18, and fixed in the rotational direction to the side gear (drive output part) 21, 21'. pressure rings 28 and 28' on both axial end faces.
and reaction brake) 29.29' are arranged.

The housing 16 is filled with cooling oil in which the friction plates 27a, 27'a and the friction disks 27b, 27'b, which serve as clutch fastening parts, are immersed, and an oil temperature sensor detects the temperature of the cooling oil. 141 is provided at this position.

The pressure ring 28, 28' is provided in a fitted state on the pinion mate shaft 19 as a member receiving the clutch engagement force, and its fitting portion has a rectangular cross section as shown in FIG. The shaft end portion 19a is fitted into the shaft end portion 19a through square grooves 28a and 2B'a, and the structure is such that no thrust force is generated due to a difference in rotation, unlike the conventional torque proportional differential limiting mechanism.

The hydraulic piston 33 moves in the axial direction (to the right in the drawing) by supplying hydraulic pressure to the hydraulic port 35, and engages both the warm type multi-disc friction clutches 27 and 27' according to the oil pressure level. The multi-disc friction clutch 27 has a fastening force of the bushing rod 32 → spacer 31 → thrust bearing 30.
→It is transmitted to the reaction plate 29 and is engaged using the pressure rings 2 and 8 as reaction force receivers, and the other wet type multi-plate friction clutch 27' is engaged by the engagement reaction force from the housing 16 serving as the engagement force.

As shown in FIG. 4, the hydraulic pressure generating device 12 is an external device that generates hydraulic pressure for clutch engagement force, and is a hydraulic pump 40.
, pump motor 41. It includes a pump pressure oil passage 42, a drain oil passage 43, a control pressure oil passage 44, and an electromagnetic proportional pressure reducing valve 46 having a valve solenoid 45.

The pump motor 41 is a motor that is activated or deactivated by a motor signal (m) from the control unit 13, and is activated or deactivated when the vehicle is running and there is a possibility that differential restriction is being performed or differential restriction is being performed. When the vehicle is stopped, a motor signal (m) is output when the vehicle is energized, and when no differential restriction is required, such as when the vehicle is stopped, a motor signal (m) is output when the vehicle is not energized.

The electromagnetic proportional pressure reducing valve 46 converts the hydraulic oil at the pump pressure supplied from the hydraulic pump 40 via the pump pressure oil line 42 into the control current signal (i) from the control unit 13.
, the pressure is controlled to a control oil pressure P proportional to the magnitude of the control m'it flow value l, and the pressure is controlled from the control pressure oil path 44 to the oil pressure port 35.
and a valve actuator that sends the control hydraulic pressure P to the oil chamber 34, and the control current signal (i) is the electromagnetic proportional pressure reducing valve 46.
is output to the valve solenoid 45.

The control unit 13 uses an on-vehicle microcomputer, and includes an input circuit 131, a RAM (random access memory) 132, a ROM (IJ-D,
133. CPU (central, processing, unit) 134, clock circuit 135,
An output circuit 136 is provided.

Incidentally, as the input sensors 14, an oil temperature sensor 141 and an accelerator opening sensor 142 are provided.

The input circuit 131 is a circuit that converts the input signals (t) and (a) from the input sensor 14 into signals that can be processed by the CPU.

The RAM 132 is a readable and writable memory, and input signals from the sensors 141 and 142 are written therein, as well as information during calculation by the CPU 134.

The ROM 133 is a read-only memory,
Information necessary for arithmetic processing by the CPU 134 is stored in advance, and is read out from the CPU 134 as needed.

The CPU 134 is a device that performs arithmetic processing on various input information according to predetermined processing conditions.

The clock circuit 135 is a circuit that sets the calculation processing time of the CPU 134.

The output circuit 136 is a circuit that outputs a control current signal (i) to the valve solenoid 45 based on a calculation result signal from the CPU 134.

The oil temperature sensor 141 is a sensor having a semiconductor sensor structure or the like that can obtain a signal with characteristics according to the oil temperature.
Output.

The accelerator opening sensor 142 detects the accelerator opening (also referred to as throttle opening) and outputs an accelerator opening signal (a
) is a sensor that outputs

Note that the accelerator opening sensor 142 is used as a sensor that determines the control current value l based on the magnitude of the accelerator opening A.

Moreover, in the ROM 133 of the control unit 13,
As shown in FIG. 5, a control characteristic map of the control current value P with respect to the accelerator opening degree A is set in advance, and as shown in FIG. 6, the correction value K increases in proportion to the oil temperature t. A correction value map is set in advance.

Next, the operation of the embodiment will be explained.

First, let us explain the operation of the embodiment and the operational flow of the differential limiting control in the seventh section.
This will be explained using the flowchart shown in the figure.

The flow of operation is as follows: step 200→step 2゜l→step 202→step 203→step 204, and in step 204, -i' is changed to the corrected control current value.
A control current signal (i) is output.

Note that step 200 is an input signal (t) from the oil temperature sensor 141 and the accelerator opening sensor 142.

(a) is the reading step, and step 201 is the accelerator opening signal (a) read in step 200.
) is a search step for searching the control current value 1 from the control characteristic map shown in FIG. This is a search step in which a correction value K is searched from the correction value map shown in FIG. 6 based on the correction value map shown in FIG. This is a calculation step of calculating -i'.

Here, as a specific example, the accelerator opening degree A is A1,
The case where the oil temperature t is tl will be described.

First, since the accelerator opening degree A is A1, the fifth
As shown in the figure, the control current value 18 becomes i*I. Since the oil temperature t is 1+, the correction value becomes + as shown in FIG. Therefore, the corrected control current value at this time is +.11.

Next, when the accelerator opening degree A remains A1 and the oil temperature t rises from tl to tl, the correction value K changes from 1 to 2, so the correction control current value also changes to 1. f'+
It changes to 2 ・i＊+.

In other words, as shown in FIG. 8, even if the accelerator opening degree A is constant, the control oil pressure P increases as the oil temperature t increases, and the control oil pressure P As a result, the desired differential limiting torque T can be obtained for a predetermined accelerator opening A regardless of changes in the oil temperature t.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. included.

For example, in the embodiment, an accelerator opening sensor is provided in addition to the oil temperature sensor as an input sensor, and the differential limiting amount is gradually changed, but differential limiting clutch pressure control is performed in an ON-OFF manner. It can also be used to correct the oil temperature of the device.
No. 9-187781, Japanese Patent Application No. 59-191270, Japanese Patent Application No. 60-157837, etc., in a control means that performs differential restriction control according to vehicle conditions such as vehicle speed and deceleration, the output It may also be used as a correction control means for correcting the oil temperature of the signal, and in this case as well, the desired differential limiting torque can be obtained without being affected by the oil temperature.

Further, in the embodiment, an electromagnetic proportional pressure reducing valve is shown as an actuator, but an example in which an electromagnetic valve that opens and closes or the like may be used to perform hydraulic control by using a control signal as a duty signal may also be used.

(Effects of the Invention) As explained above, in the vehicle differential limiting clutch pressure control device of the present invention, the wet friction clutch means is controlled in a direction in which the differential limiting torque does not change in response to changes in oil temperature. Since the fluid pressure is corrected, changes in the friction coefficient of the friction clutch due to changes in oil temperature are corrected, and a substantially constant differential limiting torque can be obtained even if the oil temperature changes.

Furthermore, even in cases where differential limiting is controlled in accordance with driving conditions, driving operations, etc., a desired differential limiting torque can be obtained by using it for correction control of output fluid pressure.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a claim showing a differential limiting clutch pressure control device for a vehicle according to the present invention, FIG. 2 is a sectional view showing a differential device incorporating a differential limiting means of an embodiment of the device of the present invention, and FIG. 2 is a Z-direction arrow view, FIG. 4 is a diagram showing the hydraulic pressure generator and control device of the embodiment device, and FIG. 5 is a diagram showing the accelerator opening degree and control current stored in advance in the control unit of the embodiment device. FIG. 6 is a map of the correction value between the oil temperature and the correction value, which is stored in advance in the control unit of the device of the embodiment, and FIG. 7 is a map of the differential limiting control operation of the device of the embodiment. Flowchart showing the flow, FIG. 8 is a control oil pressure characteristic diagram with respect to oil temperature in the example device, FIG. 9 is a clutch friction coefficient characteristic diagram with respect to oil temperature, and FIG. 10 is a differential limiting torque characteristic diagram with respect to accelerator opening. be. 1.2... Drive wheel 3... Differential means 4... Wet friction clutch means 5... Fluid pressure generation means 6... Actuator 7... Input sensor 701... Oil temperature sensor 8 ...control means

Claims (1)

[Claims] 1) A differential means for distributing and transmitting engine driving force to left and right or front and rear drive wheels while allowing a differential, and a drive input section and a drive output section of the differential means. and a wet friction clutch means for making the differential limiting torque variable by controlled fluid pressure, a fluid pressure generation means connected to the wet friction clutch means, and an actuator for controlling the fluid pressure from the fluid pressure generation means. , a control means for outputting a control signal for controlling fluid pressure based on an input signal from a predetermined input sensor; The control means includes an oil temperature sensor that detects the oil temperature of the clutch engagement portion, and the control means is a means for correcting the fluid pressure to the wet friction clutch means in a direction in which the differential limiting torque does not change in response to changes in oil temperature. A vehicle differential limiting clutch pressure control device characterized by: