JPS61178232A - Driving force transmission for four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To prevent a friction part from seizing or binding, by altering the torque transmitted to either of front wheels or rear wheels continuously, while having a friction clutch, controlling a distribution ratio of driving force for both front and rear wheels, completely released or clamped when temperature in the friction part exceeds the specified value. CONSTITUTION:In this device bearing the above caption, either of a font-wheel propeller shaft 12a or a rear-wheel propeller shaft 13a is directly connected to an output shaft 11a of a transmission 11, while the other side of the said propeller shaft 12a or 13a is connected to the output shaft 11a of the transmission 11 via a friction clutch 14. Also it alters transmission torque of this friction clutch 14 and controls the driving force transmitted to the other side of the propeller shaft 12a or 13a. In the abovementioned, there is provided with a temperature detector 15 which detects temperature of a friction part in a friction disc of the friction clutch 14. And, when the temperature of the friction part exceeds the specified one, the friction clutch 14 is made to come into a state of being completely clamped or released to the full by a heating check device 16, thus overheating in the friction part is restrained before it happens, preventing the seizure or binding from occurring.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a driving force transmission device for a four-wheel drive vehicle that can change the driving force transmitted to one of the front wheels or the rear wheels using a friction clutch. In particular, the present invention relates to a driving force transmission device that completely engages or completely releases a friction clutch when the friction clutch becomes overheated.

(Prior art) A four-wheel drive vehicle that can drive both the front wheels and the rear axle has superior rough terrain driving performance when driving both the front and rear wheels. However, on the other hand, there are also disadvantages such as tight corner braking phenomenon. For this reason, four-wheel drive vehicles generally have a friction multi-disc clutch interposed between the engine and one of the front wheels or rear wheels, and this friction multi-disc clutch drives only one of the front wheels or the rear axle. It is possible to switch between drive driving and four-wheel drive driving.

By the way, a four-wheel drive vehicle has different steering characteristics when running in four-wheel drive and when running in two-wheel drive, and tends to understeer when running in four-wheel drive. Therefore, 4 like this
Wheel drive vehicles have had the problem that if the driver inadvertently switches between four-wheel drive and two-axle drive while turning, the steering characteristics will suddenly change, impairing driving stability. .

For this reason, the present applicant has proposed a driving force transmission device for a 4-axle drive vehicle that solves these problems in Japanese Patent Application No. 59-2.
This is proposed in the specification of No. 09246.

The driving force transmission device for a four-wheel drive vehicle according to this prior application connects the rear output shaft directly to the output shaft from the transmission, and connects the front output shaft to the output shaft from the transmission via a friction clutch. A fastening force applying means that can continuously change the transmission torque of the friction clutch is provided to prevent sudden changes in steering characteristics.

(Problem to be solved by this invention) However,
In the driving force transmission device for a 4-axle drive vehicle according to such a prior application, by continuously changing the transmission torque of the friction clutch, it is possible to change from a 4-wheel drive state to a 2-wheel drive state or a 2-wheel drive state. In order to gradually change from a wheel drive state to a four-wheel drive state, if the driver frequently performs a switching operation, there is a problem in that the friction portion of the friction clutch becomes overheated. In other words, the general structure of a friction clutch is to press a friction plate into frictional contact and transmit torque (power) using the frictional force of the friction plate, but in order to gradually change the transmitted torque, it is necessary to You have to let it slide. Therefore, when the transmitted torque is changed continuously, the friction plates slip, generating heat and increasing the temperature, which may cause the friction plates to seize up.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above problems, and as shown in FIG. 1, the front wheel propulsion shaft 12a or One of the rear wheel propulsion shafts 13a is directly connected, and the other of the front wheel propulsion shaft 12a or the rear wheel propulsion shaft 13a is connected to the output shaft 11a of the transmission 11 via a friction clutch 14, and the transmission torque of the friction clutch 14 is Change the front wheel propulsion shaft 12a or the rear wheel propulsion shaft 1
A driving force transmission device for a four-wheel drive vehicle that controls the driving force transmitted to the other of the friction clutches 3a includes a temperature sensor 15 that detects the temperature of the friction portion of the friction plate of the friction clutch 14; A heat generation prevention means 16 is provided which completely engages or completely releases the friction clutch 14 when the temperature of the friction portion exceeds a predetermined temperature based on the output signal.

(Function) According to this driving force transmission device for a four-wheel drive vehicle, when the friction parts such as the friction plates of the friction clutch 14 overheat, the friction clutch 14 is completely engaged so that the friction plates do not slip. or be placed on complete release. therefore,
In the friction clutch 14, the temperature of the friction portion thereof does not further rise, and the friction plates and the like can be prevented from seizing.

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

FIGS. 2 to 6 are diagrams showing one embodiment of the present invention.

First, an overview of a four-wheel drive vehicle will be explained with reference to FIG. is two wheels-
It is connected to a rear propeller shaft (rear propulsion shaft) 24R and a front propeller shaft (front propulsion shaft) 24F via a transfer 23 for switching four wheels. The rear wheel propeller shaft 24 is connected to the left and right rear axle 2 through the rear wheel differential 25FL and the left and right axles 26RL and 26R'k.
Similarly, the front wheel propeller shaft 24F connects to the left and right front wheels 27F via the front wheel differential 25F and the left and right axles 26FL'' and 26FR.
L, connected to 28FR.

In the transfer 23, as shown in FIG. 3'', an input shaft 30 directly connected to the output shaft of the transmission 22 is rotatably housed in a transfer case 28, which is formed by joining two members 28a and 28b with bolts 29. In addition, the rear export force shaft 3 is connected to the rear propeller shaft 24.
1 is rotatably supported by a bearing 32.

The input shaft 30 and the rear export force shaft 31 are each coaxially spline-coupled to a joint member 33 and connected to rotate together with the joint member 33. The coupling member 33 has a drum 44 of a hydraulic friction multi-disc clutch, which will be described later, arranged on its outer periphery, and is rotatably inserted into a bearing holder 34 fixed to the transfer case 28 with bolts 34a.

A first hollow shaft 38 is rotatably inserted into the input shaft 30, and a second hollow shaft 39 spline-coupled with the first hollow shaft 38 is rotatably inserted into the input shaft 30 via a needle bearing 43. . A drive gear 38a meshing with a counter gear 40a is integrally formed on the outer periphery of the first hollow shaft 38. The counter gear 40a is integrally formed with a counter shaft 40 rotatably supported by the transfer case 28 via a bearing 41, and meshes with a driven gear 42 provided on a front export force shaft connected to the front propeller shaft 24F. ing. The second hollow shaft 39 has a hub 39a that is integrally formed and projects outward in the radial direction, and a friction multi-disc clutch 49 (friction clutch) is installed between the hub 39a and the drum 44 described above. .

The friction multi-disc clutch 49 includes a plurality of drive plates (friction plates) 45 that are spline-coupled to the inner peripheral wall of the drum 44 and spline-coupled to the hub 39a of the second hollow shaft 39.
A plurality of driven plates (friction plates) 46 are arranged alternately in the axial direction with the live plate 45, and both the inner and outer circumferential surfaces of the drum 44 and the joint member 33 are in liquid-tight and slidable contact with the drum 44 and the joint member 33, respectively. a substantially annular piston 48 that defines an oil chamber 47; a spring 53 that is compressed between a retainer 52 attached to the joint member 33 and the piston 48 and urges the piston 48 toward the oil chamber 47; It is equipped with The oil chamber 47 is connected to the first oil passage 35 formed in the joint member 33.
a, second oil passage 35b formed in the bearing holder 34
and the third oil passage 3 formed in the transfer case 28
Hydraulic boat 35 of transfer case 28 via 5c
It is connected to d. When high-pressure oil is supplied from a control device 51 (described later) to an oil chamber 47 via a hydraulic boat 35d and first, second, and third oil passages 35a, 35b, and 35c, the friction multi-disc clutch 49 is activated by a piston. 48 moves to the left in the figure against the elastic force of the spring 53, and the drive plate 45
and the driven plate 46 are brought into frictional contact, and the joint member 3
3 and the second hollow shaft 39, that is, the input shaft 30 and the front export force shaft.

Note that 30a is a first lubricating oil passage formed in the input shaft 30;
31a is a second lubricating oil passage formed in the rear export force shaft 31;
9b is a first clutch lubricating oil passage formed in the second hollow shaft 39, 39c is a second clutch lubricating oil passage formed in the hub 39a of the second hollow shaft 39, and 44a is a third clutch lubricating oil passage formed in the drum 44. The first and second lubricating oil passages 30a and 31a supply lubricating oil to the needle bearing 43, etc., and the first, second and third clutch lubricating oil passages 39b, 39c and 44a supply lubricating oil to the needle bearing 43, etc. The drive plate 45 and driven plate 46 of the multi-plate clutch 49 and the sliding surfaces (
Supply lubricating oil to friction parts). Further, an oil temperature sensor (temperature detector) 37 is attached to the member 28a of the transfer case 28 at a position corresponding to the third clutch lubricating oil passage 44a of the drum 44. This oil temperature sensor 37 is
The sliding surface between the drive plate 45 and the driven plate 46 is lubricated, and the temperature of the lubricating oil flowing out from the third clutch lubricating oil path 44a into the transfer case 28 is detected as the temperature of the sliding surface.

Again in FIG. 2, 51 is a control device (heat generation prevention means)
This control device 51 includes the oil temperature sensor 37, a gear position sensor 56 that detects the gear position of the transmission 22, a vehicle speed sensor 54 that detects the vehicle speed, and a lateral acceleration that acts on the vehicle body. Acceleration sensor 55
and an accelerator sensor 50 that detects the valve opening of the throttle valve of the engine 21 are connected. As described above, the oil temperature sensor 37 detects the temperature of the lubricating oil and outputs a signal indicating the temperature to the control device 51, and the gear position sensor 56 outputs a signal indicating the gear position of the transmission 22 to the control device. 51, and the acceleration sensor 5
5 outputs a signal indicating lateral acceleration to the control device 51, and an accelerator sensor 50 outputs a signal indicating the valve opening of the throttle valve to the control device 51. Note that the accelerator sensor 50 can also be configured to detect the amount of depression of the accelerator pedal.

As shown in FIGS. 4 and 5, the control device 51 includes a hydraulic circuit 57 that supplies pressure oil to the oil chamber 47 of the friction multi-disc clutch 49, and an electric control system that controls the hydraulic pressure generated by this hydraulic circuit 57. A circuit 58 is provided.

As shown in FIG. 4, the hydraulic circuit 57 is interposed between a pump 59 connected to the oil chamber 47 of the friction multi-disc clutch 49, and the oil chamber 47 of the friction multi-disc clutch 49 and the reservoir tank 61. and a solenoid valve 60. The pump 59 is driven by the engine 21 via a belt 62, pressurizes oil in the reservoir tank 61, and discharges pressurized oil at a constant pressure. The solenoid 60a of the solenoid valve 6o is connected to an electric control circuit 58, and the oil chamber 47 is opened at an opening degree according to the current value supplied to the solenoid 60a by the electric control circuit 58.
and the reservoir tongue 61. That is, this solenoid valve 6o communicates between the oil chamber 47 and the reservoir tank 61 with an opening area corresponding to the current value supplied to the solenoid 60a, and transfers the pressure oil at a constant pressure discharged by the pump 59 to the reservoir tank 61. and controls the oil pressure (clutch pressure) in the oil chamber 47. Note that this solenoid valve 60 has a relief function, and when the hydraulic pressure in the circuit becomes excessive, the solenoid 6
The oil chamber 47 is opened to the reservoir tank 61 regardless of whether or not 0a is energized.

As shown in FIG. 5, the voltage control circuit 58 includes a driving force calculation circuit 63 to which a gear position sensor 56, a vehicle speed sensor 54, and an accelerator sensor 50 are connected, and a distribution ratio determining circuit 64 to which an acceleration sensor 55 is connected. , driving force calculation circuit 63
, an arithmetic circuit 65 to which the distribution ratio determining circuit 64 and the oil temperature sensor 37 are connected, and a drive circuit 6 to which the arithmetic circuit 65 is connected.
It is equipped with 6 and. The driving force calculation circuit 63 calculates the driving force of the vehicle based on the gear position of the transmission 22, the vehicle speed, and the valve opening of the throttle valve and outputs a signal displaying the driving force. Based on the directional acceleration, the front wheels 27F and 27F, and the rear axle 271
i! A driving force distribution ratio of 5.27 Yu is determined and a signal indicating the distribution ratio is output. Then, the arithmetic circuit 65
When the lubricating oil temperature is below a predetermined temperature, a signal that calculates the oil pressure (clutch pressure) to be supplied to the oil chamber 47 of the friction multi-disc clutch 49 based on the driving force and distribution ratio and displays the clutch pressure. However, when the lubricating oil temperature exceeds a predetermined temperature, the friction multi-disc clutch 49 releases the clutch pressure, that is, the friction multi-disc clutch 49 disconnects between the input shaft 3° and the front export force shaft. When this occurs, a signal indicating the latch pressure (for example, zero) is output. The drive circuit 66' is the arithmetic circuit 6.
A current having a value corresponding to the clutch pressure determined in step 5 is output to the relenoid 60a of the solenoid valve 60.

Next, the effect will be explained.

This driving force transmission device for a four-wheel drive vehicle has a control device 51 that repeatedly executes a series of processes shown in the flowchart of FIG. 49 transmission torque, that is, front wheel 27FL,
By changing the driving force transmitted to the 27FR according to the driving force and lateral acceleration of the vehicle,
Controls the distribution ratio of the driving force between 27 and 27RR, and
When the lubricating oil temperature exceeds a predetermined temperature, that is, when the friction multi-disc clutch 49 is in an overheated state, the friction multi-disc clutch 49 is released regardless of the driving force or lateral acceleration of the vehicle.

Hereinafter, a detailed explanation will be given based on the flowchart of FIG.

First, in step P0, the lubricating oil temperature T is read from the output signal of the oil temperature sensor 37, and in the next step P2, it is determined whether or not the lubricating oil temperature T exceeds a predetermined temperature TI. It is determined whether the clutch 49 is in an overheated state. Then, in step P2, the lubricating oil temperature T becomes a predetermined temperature T. If it is determined that it exceeds (T>T,),
In step P3, the friction multi-disc clutch 49 is released. That is, in step P3, the solenoid valve 60 has the maximum opening degree, the clutch pressure is set to the minimum value, and the friction multi-disc clutch 49 is set in the released state. As a result, the lubricating oil temperature T becomes the predetermined temperature T. If it is determined that the friction multi-disc clutch 49' is in an overheated state, the friction multi-disc clutch 49 will no longer generate heat, and the drive plate 45 and driven plate 46 may seize. It disappears.

On the other hand, in step P2, the lubricating oil temperature T or the predetermined temperature T is determined. If it is determined that the following is true, the process proceeds to step P4.

In step P4, the lateral acceleration is read from the output signal of the acceleration sensor 55, and in the next step P5, the distribution ratio determination circuit 64 determines the distribution ratio of the driving force between the front and rear axes based on the lateral acceleration. Then, the next step P6
Then, the vehicle speed is read from the output signal of the vehicle speed sensor 54, the valve opening of the throttle valve is read from the output signal of the accelerator sensor 50 in step P7, and the gear position of the transmission 22 is read from the output signal of the gear position sensor 56 in step P8. In the next step P, the driving force calculation circuit 63 calculates the driving force of the vehicle based on the vehicle speed, the opening degree of the throttle valve, and the gear position of the transmission 22. Thereafter, in step P1o, clutch pressure is calculated based on the distribution ratio determined in step P and the driving force calculated in step P9. Then, in the next step P1□, a current having a value corresponding to the clutch pressure calculated in the above step P1o is energized to the solenoid 60a of the electromagnetic valve 60,
By changing the opening degree of this solenoid valve 60, the clutch pressure can be adjusted to step P.
,. The value calculated by Therefore, the friction multi-disc clutch 49 transfers torque to the input shaft 30 according to the clutch pressure.
and the front export power shaft, and the driving force corresponding to the lateral acceleration is transmitted to the front wheels 27F and 27, and the distribution ratio of the driving force between the front and rear wheels is continuous according to the lateral acceleration. controlled by. As a result, it is possible to improve the driving performance of the vehicle, such as enabling power slide driving. That is, this driving force transmission device includes a friction multi-plate latch 49.
is functioning normally, the steering characteristic is controlled by continuously changing the transmission l/lux of the friction multi-disc clutch 49 to control the distribution ratio of the driving force between the front and rear axes to a value that corresponds to the lateral acceleration. Sudden changes, etc., are prevented.

In the embodiment described above, when the friction multi-disc clutch 49 overheats, the clutch pressure is set to the minimum value and the friction multi-disc clutch 49 is released, but the clutch pressure is set to the maximum value and the friction multi-disc clutch 49 is fully engaged. Even in a state where there is no space between the drive plate 45 and the driven plate 46, heat generation is prevented.

(Effects of the Invention) As explained above, according to the drive force transmission device for a four-axle drive vehicle according to the present invention, the torque transmitted to one of the front wheels or the rear wheels is continuously changed to generate the drive force of the front and rear axles. The friction clutch, which controls the distribution ratio, is completely released or fully engaged when the temperature of the friction part exceeds a predetermined temperature, so the friction part does not overheat and seize, improving its reliability. improves.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a driving force transmission device for a four-axis drive vehicle according to the present invention. 2 to 6 are diagrams showing a driving force transmission device for a four-axis drive vehicle according to an embodiment of the present invention, in which FIG. 2 is a schematic overall view, and FIG. 3 is a sectional view of main parts of the mechanism. FIG. 4 is a circuit diagram, FIG. 5 is a block diagram, and FIG. 6 is a flow chart. 11.22...Transmission, 11a...Output shaft, 12a, 2.4F...Front wheel propulsion shaft, 13a, 2
4.・・・・・・Rear propulsion shaft, 14.49・・・・・・
Friction multi-plate clutch (friction clutch), 15.37...
... Temperature detector, 16.51 ... Heat generation prevention means.

Claims (1)

[Claims] One of the front wheel propulsion shaft or the rear wheel propulsion shaft is directly connected to the output shaft of the transmission, and the other of the front wheel propulsion shaft or the rear wheel propulsion shaft is connected to the output shaft of the transmission via a friction clutch. In a driving force transmission device for a four-wheel drive vehicle that controls the driving force transmitted to the other of the front wheel propulsion shaft or the rear wheel propulsion shaft by changing the transmission torque, the temperature of the friction portion of the friction plate of the friction clutch is detected. The present invention is characterized in that it is provided with a temperature detector and a heat generation prevention means that completely engages or completely releases the friction clutch when the temperature of the friction portion exceeds a predetermined temperature based on the output signal of the temperature detector. A driving force transmission device for four-wheel drive vehicles.