JP2652674B2 - Power distribution device for four-wheel drive vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a power distribution device for a four-wheel drive vehicle equipped with a wet hydraulic multi-plate clutch that distributes power to front and rear wheels.

[Prior art]

As such a power distribution device for a four-wheel drive vehicle, Japanese Patent Application Laid-Open
The thing described in 61-155027 is known conventionally. This is one in which two wet-type hydraulic multi-plate clutches for front wheel drive and rear wheel drive are arranged in a case of a transfer device that transmits power by branching from a transmission output shaft to front and rear wheels,
According to the hydraulic control, power can be continuously distributed to the front and rear wheels at an arbitrary ratio. Here, these wet hydraulic multi-plate clutches are configured such that the hydraulic oil is shared with the lubricating oil of gears and bearings in the transfer device, and the hydraulic piston for pressing the clutch plate rotates together with the clutch drum. ing.

[Problems to be solved by the invention]

Since the hydraulic piston rotates together with the clutch drum in this way, centrifugal hydraulic pressure is generated in the hydraulic chamber for driving the hydraulic piston with the rotation of the clutch drum, and this is added to the control hydraulic pressure and acts on the hydraulic piston. I will be. Therefore, the wet hydraulic multi-plate clutch cannot perform desired hydraulic control because the transmission torque is excessively larger than the set value corresponding to the control hydraulic pressure, and when the vehicle reaches a middle to high speed range and the centrifugal hydraulic pressure is large, the linear The internal hydraulic torque generated by the difference in the effective weight of the front and rear wheels due to the difference in the axle weight distribution of the vehicle during running and the shift of the center of gravity during acceleration running cannot be sufficiently absorbed by the wet hydraulic multi-plate clutch as a torque limiter. In addition, there are inconveniences such as deterioration of acceleration performance, deterioration of fuel efficiency, generation of vibration noise, and the like. In addition, the wet hydraulic multi-plate clutch uses the same lubricating oil as the working oil for gears, so that when the four-wheel drive running state causes large turning and slipping action occurs, appropriate friction characteristics can be obtained. However, there is a problem that a stick-slip is caused and vibration noise is generated. Accordingly, the present invention prevents the generation of centrifugal oil pressure in the hydraulic chamber of the wet-type hydraulic multi-plate clutch and the occurrence of stick-slip when the sliding action is performed in order to solve the above-mentioned inconveniences. It is an object of the present invention to be able to maximize the turning performance and sufficiently satisfy the driver's driving preference.

[Means for Solving the Problems]

For this purpose, the present invention relates to a four-wheel drive vehicle in which the front and rear wheels are configured to transmit power in accordance with pressure control of hydraulic oil to two wet-type hydraulic multi-plate clutches. Interposed between the final gear and the differential case in the horizontal transaxle with transfer, and the other wet hydraulic multi-plate clutch is divided and arranged in the independent differential after the transfer and installed in the middle of the transmission shaft. The hydraulic piston in these wet hydraulic multi-plate clutches is configured such that the case member of the transaxle or the independent differential, which is an immovable member, is prevented from rotating as a cylinder, and is slidably fitted to the cylinder. The working end opposite to the working hydraulic chamber is connected to a retainer plate fitted inside the end of the clutch drum of the wet hydraulic multi-plate clutch through a bearing. FF running, in which the clutch plate in the clutch drum is pressed to press the clutch plate, and the control system of the double wet hydraulic multi-plate clutch transmits power only to the front wheels via one wet hydraulic multi-plate clutch. A switch that allows selection of each driving mode between FR traveling that transmits power only to the rear wheel via the other wet hydraulic multi-plate clutch and 4WD traveling that transmits power to front and rear wheels via both wet hydraulic multi-plate clutches A group is provided.

[Action]

In such a means, even if the clutch plate in the clutch drum rotates due to the rotation of the final gear and the transmission shaft, the hydraulic pistons in the respective wet hydraulic multi-plate clutches do not rotate, and the hydraulic pistons and the transaxle case members are not rotated. No centrifugal hydraulic pressure is generated in each hydraulic chamber formed between them. In addition, one or both wet hydraulic multi-plate clutches can obtain desired friction characteristics by using an appropriate hydraulic oil having a predetermined composition, and can be used when internal circulation torque between the front and rear wheels is generated or when four-wheel drive is used. If you steer heavily in the state,
The clutch plate works smoothly without stick-slip. By controlling each wet hydraulic multi-plate clutch in accordance with the operation of the switch group, the driver can select each of the FF, FR, and 4WD running modes capable of distributing power between the front and rear wheels.

【Example】

Hereinafter, an embodiment of the present invention will be specifically described with reference to the drawings. FIG. 2 shows a power transmission system of a four-wheel drive vehicle equipped with a transversal transaxle with a transfer to which one embodiment is applied, wherein an engine 1, a clutch 2, and a manual transmission 3 are arranged laterally in front of the vehicle body. The front wheel differential device 4, the transfer device 5, the propeller shaft 6, and the rear wheel differential device 8 are disposed behind these components. And from engine 1 to clutch 2
The power input to the manual transmission 3 through the gearbox is appropriately shifted there, and is input from the output gear 9 to the front wheel differential 4 through the final gear 10 and the first wet hydraulic multi-plate clutch 7. Power is transmitted to the left and right front wheels from the vehicle. Further, the transfer gear 11 of the transfer device 5 meshes with the final gear 10, and the power from the transfer device 5, which is taken out rearward from the transfer gear 11 via the transfer shaft 21 and the pair of deflection bevel gears 12, The power is input to the rear wheel differential 8 via the propeller shaft 6, the second wet hydraulic multi-plate clutch 28, and the final gear 13, from which power is transmitted to the left and right rear wheels. Here, the first and second two wet hydraulic multiple disc clutches 7,
Numeral 28 denotes oil pumps 14a and 14b, regulator valves 15a and 15b, transfer clutch valves 16 which are directly driven by an electric motor or an engine, respectively, as shown in FIG.
a, 16b, duty solenoid valves 17a, 17b, and a dedicated hydraulic control system having pilot valves 18a, 18b supply an appropriate control oil pressure according to the traveling state. Since these hydraulic control systems have substantially the same configuration, one of them will be described. Duty pressure is controlled by a hydraulic circuit system which is adjusted to a predetermined hydraulic pressure from an oil pump 14a by a regulator valve 15a and reaches a wet hydraulic multi-plate clutch 7. A transfer clutch valve 16a is interposed, and a duty solenoid valve 17a for discharge control is inserted into a pilot pressure circuit system having a pilot valve 18a. By controlling the duty solenoid valves 17a and 17b in both hydraulic control systems to the desired duty pressures respectively according to the duty signal from the control unit 19, the transfer clutch valves 16a and 16b
Are individually adjusted to a desired clutch pressure. The relationship between the duty ratio, the duty pressure and the clutch pressure is as shown in FIG. As shown in FIG. 1 (a), a first wet-type hydraulic multi-plate clutch 7 having such a hydraulic control system is provided with a final gear 10 in a horizontal transaxle with a transfer and a differential case for a front-wheel differential device 4. It is interposed between 22 and. That is, the first wet hydraulic multi-plate clutch 7 uses the differential case 22 as the clutch hub 7b,
One end of the clutch drum 7a covering this
The other end of the clutch drum 7a is rotatably supported by a case member 24 via a support plate 23 with a window. On the inner periphery of the clutch drum 7a, a plurality of ring-shaped clutch plates 7c are spline-fitted together with retainer plates 7d at both ends, while the clutch hub 7b
A plurality of ring-shaped clutch discs 7e are alternately arranged on the outer periphery of the clutch plate 7c and are spline-fitted.
d, a clutch disc 7e constitutes a multi-plate clutch. Here, a piston 7f for applying a pressing force to the retainer plate 7d has a ring shape, and is a case member which is an immovable member.
A hydraulic chamber 7g that is slidably fitted to 24 and is prevented from rotating through a knock pin 25, and forms a hydraulic chamber 7g communicating with the transfer clutch valve 16a between itself and the case member 24. The working end opposite to the hydraulic chamber 7g is brought into contact with the retainer plate 7d via a release bearing 27 of an angular contact. In the release bearing 27, the outer race 27a is in contact with the piston 7f, and the inner race 27b is as shown in FIG.
As shown in the figure, a retainer portion 27 that penetrates through the window 23a of the support plate 23 and is spline-fitted to the inner periphery of the clutch drum 7a.
It is in contact with the retainer plate 7d via c. On the other hand, as shown in FIG. 1B, the second wet-type hydraulic multi-plate clutch 28 is compactly arranged together with its hydraulic control system in a differential carrier portion which is a case member of the rear wheel differential device 8. In other words, the differential carrier 29 is connected to the extension case 32 around the input shaft 31 by projecting forward so as to cover the loose fit portion between the drive pinion 30 of the rear wheel differential 8 and the input shaft 31 on the propeller shaft 6 side. A cylinder unit 33 is integrally formed as a stationary member, and a valve unit 26 integrally formed with the valves 15b, 16b, 17b, and 18b is provided on a lower surface of the cylinder unit 33, as shown in FIG. The motor-driven oil pumps 14b are respectively fixed, and the second wet-type hydraulic multi-plate clutch 28 is disposed in the cylinder portion 33. Here, in the second wet hydraulic multi-plate clutch 28, the clutch drum 28a is welded and fixed to the flange 31a at the rear end of the input shaft 31, and the clutch hub 28b is spline-fitted to the shaft 30a of the drive pinion 30. Then, it is locked to the end of the input shaft 31 via a thrust washer 34. On the inner periphery of the clutch drum 28a, a plurality of ring-shaped clutch plates 28c are spline-fitted together with the retainer plates 28d at both ends, while on the outer periphery of the clutch hub 28b, a plurality of ring-shaped clutch disks 28e are provided. The clutch plate 28c, the retainer plate 28d, and the clutch disk 28e constitute a multi-plate clutch by being alternately arranged with the clutch plates 28c and spline-fitted. A ring-shaped piston 28f for applying a pressing force to the retainer plate 28d is provided on the cylinder portion 3 as an immovable member.
A hydraulic chamber 28g communicating with the transfer clutch valve 16b is formed between the partition wall 33a and the inner guide cylinder 33b so as to be slidably fitted in the inside 3 and an operating end opposite to the hydraulic chamber 28g. The portion is in contact with the retainer plate 28d via a release bearing 35 of an angular contact. The release bearing 35 is configured such that the outer race 35a abutting on the piston 28f is connected to the inner guide cylinder 33 via a claw 35b.
The inner race 35c is spline-fitted to the inner periphery of the clutch drum 28a, and the rotation of the outer race 35a prevents the piston 28f from rotating relative to the cylinder portion 33. . On the other hand, the shaft 30a of the input shaft 31 and the drive pinion 30
Are formed with oil passages 31b, 30b so as to communicate the outer peripheral side of the clutch drum 28a and the inner peripheral side of the clutch hub 28b. Then, the hydraulic oil in the cylinder section 33 is supplied to the clutch drum 28
The oil is drawn up on the outer periphery of a and supplied to the oil passage 30b by an oil guide (not shown), and the hydraulic oil is guided to the inner peripheral side of the clutch hub 28b through the oil passage 30b, so that the spline portion is provided in the radial direction (not shown). Through the oil passage, clutch plate
The multi-plate clutch such as the clutch disk 28c and the clutch disk 28e is lubricated. In order to prevent the hydraulic oil from leaking, oil seals 36, 37 are provided on the inner peripheral portion of the partition wall 33a of the cylinder portion 33 and the inner peripheral portion of the front portion of the extension case 32, respectively.
Is installed. Further, since the characteristics of the lubricating oil for hypoid gear and the hydraulic oil in the differential device are different, the partition wall 33a
The oil seal 36 on the inner peripheral portion is configured to maintain liquid tightness with each other. The control unit 19 receives various signals such as a throttle opening signal, a rear wheel rotation signal, a front wheel rotation signal, a range signal, and an idle signal to constantly determine the running state of the vehicle. An optimal duty ratio signal is output to each of the duty solenoid valves 17a, 17b from a table map preset as a parameter to control the clutch pressure of the first and second wet hydraulic multi-plate clutches 7, 28. ing. Here, the control unit 19 receives the FF from the FF switch 40a.
Drive command signal, FR drive command signal from FR switch 40b, 4WD capable of power distribution between front and rear wheels from control 4WD switch 40c
The driving command signals are input. The control unit 19 outputs a duty ratio signal of 0% only to one duty solenoid valve 17a based on the FF running command signal, and conversely outputs only the other duty solenoid valve 17b based on the FR running command signal. A duty ratio signal of 0% is output, and both duty solenoid valves 17 are output based on a 4WD running command signal capable of distributing power between the front and rear wheels.
A duty ratio signal in the range of 0% to 100% is output from the table maps preset in a and 17b. In the four-wheel drive vehicle having the above configuration, the power transmitted from the engine 1 to the manual transmission 3 via the clutch 2 is appropriately shifted there, and one of the power is transmitted from the final gear 10 to the first gear.
To the front wheel differential 4 via the wet hydraulic multi-plate clutch 7 and the other to the rear wheel differential 8 via the second wet hydraulic multi-plate clutch 28 to drive four wheels. . In this case, the power is distributed to the front wheel side and the rear wheel side according to the transmission torque of each wet hydraulic multi-plate clutch 7, 28. The distribution ratio gradually increases from the FF state of the front wheels 100% and the rear wheels 0% by the change of the clutch pressure according to the duty ratio signal from the control unit 19, and the rear wheel side is gradually increased to directly connect the front and rear wheels to the 4W.
After the D state, it changes within a range until the front wheel becomes 0% and the rear wheel becomes 100% in the FR state. If the difference in the axle weight distribution between the front and rear wheels of the vehicle, the sudden acceleration, and the movement of the center of gravity during climbing a hill causes a difference in the effective diameter of the front and rear wheels during the four-wheel drive, the difference between the front and rear wheels is determined. Relative rotation occurs. In such a case, the first or second wet hydraulic multi-plate clutch 7, 28 functions as a torque limiter by being controlled to a desired clutch pressure, and the clutch plate 7c or 28c on the clutch drum 7a or 28a side.
And clutch disc 7e on the clutch hub 7b or 28b side
Alternatively, a slip occurs between the front wheel and the wheel 28e to absorb the internal circulation torque caused by the rotation difference between the front and rear wheels. Therefore, acceleration performance and fuel efficiency during four-wheel drive traveling can be improved. Also, 4
If the vehicle is steered significantly while the wheel drive vehicle is running, internal circulation torque is generated between the front and rear wheels due to the difference in turning radius between the front and rear wheels. At the time of insertion, inconvenience such as occurrence of engine stall occurs. In such a case, the first or second wet hydraulic multi-plate clutch 7, 28 detects the above-mentioned front-rear rotation speed,
Pressure reduction is controlled to a desired clutch pressure in accordance with the rotation ratio or the rotation difference, and slippage occurs in the first or second wet-type hydraulic multiple disc clutches 7, 28 to address this problem. Therefore, the tight corner braking phenomenon at the time of turning can be avoided. When the first or second wet hydraulic multi-plate clutches 7, 28 perform such a sliding action, the clutch plates such as the clutch plates 7c or 28c and the clutch discs 7c or 28e may be placed in an appropriate hydraulic oil having a predetermined composition. , The desired frictional properties are obtained and no stick-slip occurs. Therefore, unpleasant vibrations and noises do not occur particularly at the time of low-speed maximum steering, and desired reliability and durability can be obtained for the friction material. In such a four-wheel drive vehicle, each drive mode of FF, FR, and 4WD capable of distributing power between the front and rear wheels can be selected. For example, when the FF switch 40a is operated, a duty ratio signal of 0% is output only to one of the duty solenoid valves 17a, and only the first wet hydraulic multi-plate clutch 7 is directly connected, and the second wet hydraulic multi-plate clutch 28 Is released, power is transmitted only to the front wheels, and the vehicle enters the FF running mode. When the FR switch 40b is operated, a 0% duty ratio signal is output only to the other duty solenoid valve 17b to release the first wet hydraulic multi-plate clutch 7 and directly connect only the second wet hydraulic multi-plate clutch 28. Therefore, power is transmitted only to the rear wheels, and the vehicle enters the FR running mode. When the control 4WD switch 40c is operated, the two-duty solenoid valve 17
A duty ratio signal in the range of 0% to 100% is output to each of a and 17b, and the pressure of the hydraulic oil to the first and second wet-type hydraulic multi-plate clutches 7 and 28 is changed according to the traveling state. In this way, the control 4WD driving mode in which power is always distributed to the front and rear wheels is set. Therefore, by appropriately selecting each traveling mode, the vehicle's stability, starting performance, and turning performance can be maximized, and the driver's driving preference can be sufficiently satisfied. Looking at the behavior of each wet hydraulic multi-plate clutch 7, 28 itself, as the final gear 10, the input shaft 31 rotates, the clutch drums 7a, 28a together with the clutch plates 7c, 28c, the inner race 27b of the release bearings 27, 35 Even when the pistons 7f and 28f rotate, the pistons 7f and 28f are prevented from rotating by the case member 24 and the cylinder 33, which are immovable members, and do not rotate. Therefore, no centrifugal hydraulic pressure is generated in the hydraulic chambers 7g, 28g formed between the pistons 7f, 28f, the case member 24, and the cylinder portion 33, and the hydraulic pressure is not applied to the clutch plates 7c, 28c and the like except for the pressing force by the control hydraulic pressure. Unnecessary pressing force is not applied. Therefore, hydraulic chamber 7g, 2
The 8g hydraulic control will be accurate and delicate hydraulic control will be possible. Also, in each of the wet hydraulic multi-plate clutches 7, 28, since the hydraulic chambers 7g, 28g are formed in the case member 24 and the cylinder portion 33, a hydraulic chamber is provided in the rotating member, and a seal ring is provided between the stationary member and the rotating member. Compared to the method of forming the hydraulic circuit to be used, there is no need for a seal ring or the like, so there is less danger of pressure drop due to leakage. . Since the responsiveness of the working oil pressure is good, the behavior of the vehicle can be controlled by instantaneously changing the power distribution ratio when the front wheel or the rear wheel slips. In addition, since one of these wet hydraulic multi-plate clutches 7, 28 is arranged on the outer periphery of the differential in a horizontal transaxle with a transfer and the other is arranged in an independent differential, the transaxle is The length is not increased, and the configuration of the transfer device becomes compact. Therefore, the transaxle maintains its rigidity and does not increase vibration or noise. Also, the space in the vehicle interior is not reduced. Although the above embodiment is based on a four-wheel drive vehicle with a front engine, it may be configured on a four-wheel drive vehicle with a rear engine. The present invention can be applied to not only manual transmission vehicles but also automatic transmission vehicles and vehicles with continuously variable transmissions.

【The invention's effect】

As described above, according to the present invention, even when the clutch drum is rotated by the rotation of the final gear and the transmission shaft, the hydraulic piston in each wet hydraulic multi-plate clutch does not rotate, and the transaxle or the independent differential No centrifugal hydraulic pressure is generated in each hydraulic chamber formed between the case members. Therefore, each wet-type hydraulic multi-plate clutch distributes power at an arbitrary ratio to the front and rear wheels by an appropriate transmission torque according to the control oil pressure. When internal circulation torque is generated due to a rotation difference between the front wheel and the rear wheel, one or two wet-type hydraulic multi-plate clutches use appropriate hydraulic oil having a predetermined composition so that the wet-type hydraulic multi-plate This allows the clutch to exhibit the desired friction characteristics and smoothly absorbs without stick-slip and absorbs this sufficiently, thus avoiding tight corner braking when turning and accelerating when traveling straight ahead. The performance and fuel efficiency can be improved, and the generation of vibration noise can be prevented. By operating the switch group, it becomes possible to select each driving mode of FF, FR, and control 4WD that can distribute power between front and rear wheels, so that the vehicle's stability, starting performance, turning performance can be maximized, It can also respond to the driver's driving preferences.

[Brief description of the drawings]

1 (a) and 1 (b) are cross-sectional views of an essential part showing an embodiment of the present invention, FIG. 1 (c) is a cross-sectional view taken along line CC of FIG. 1 (a), and FIG. FIG. 1D is a sectional view taken along line DD of FIG. 1B.
FIG. 2 is a skeleton diagram of a transmission system of a four-wheel drive vehicle to which one embodiment is applied, FIG. 3 is a hydraulic circuit diagram used in one embodiment,
FIG. 4 is a characteristic diagram of the duty pressure and the clutch pressure. 1 ... engine, 2 ... clutch, 3 ... manual transmission,
4 ... Differential device for front wheels, 5 ... Transfer device, 6 ...
... Propeller shaft, 7 ... First wet hydraulic multi-plate clutch, 7a ... Clutch drum, 7b ... Clutch hub, 7c ...
… Clutch plate, 7d …… Retainer plate, 7e ……
Clutch disk, 7f …… Piston, 7g …… Hydraulic chamber, 8
... differential gear for rear wheels, 9 ... output gear, 10 ... final gear, 11 ... transfer gear, 12 ... bevel gear,
13 ... Final gear, 14a, 14b ... Oil pump, 15
a, 15b …… Regulator valve, 16a, 16b …… Transfer clutch valve, 17a, 17b …… Duty solenoid valve, 18a, 18b …… Pilot valve, 19 …… Control unit, 21 …… Transfer shaft, 22 …… Differential Case, 23: Support plate, 23a: Window, 24: Case member, 25: Dowel pin, 26: Valve unit, 27 ...
… Release bearing, 27a …… Outer race, 27b ……
Inner race, 27c Retainer section, 28 Second wet hydraulic multi-plate clutch, 28a Clutch drum, 28b Clutch hub, 28c Clutch plate, 28d Retainer plate, 28e Clutch disc , 28f ... piston, 28g ... hydraulic chamber, 29 ... differential carrier, 30 ... drive pinion, 30a ... shaft, 30b ... oil passage, 31 ... input shaft, 31a ... ... flange, 31b ... … Oilway,
32 …… Extension case, 33 …… Cylinder part, 33
a… Partition wall, 33b… Inner guide tube, 34… Thrust washer, 35… Release bearing, 35a… Outer race, 35b… Claw, 35c… Inner race, 36, 37… Oil seal, 40a …… FF switch, 40b …… FR switch,
40c ... Control 4WD switch.

Claims (1)

(57) [Claims] 1. A four-wheel drive vehicle in which power is distributed between front and rear wheels according to pressure control of hydraulic oil to two wet-type hydraulic multi-plate clutches, wherein the one wet-type hydraulic multi-plate clutch is provided with a transfer-side lateral. The other wet-type hydraulic multi-plate clutch is interposed between the final gear and the differential case in the stationary transaxle, and is separately arranged in the independent differential after the transfer, and is interposed in the middle of the transmission shaft. The hydraulic piston in the wet-type hydraulic multi-plate clutch of the present invention is configured such that the transaxle or the case member of the independent differential device, which is an immovable member, is stopped as a cylinder, and is slidably fitted to these cylinders. The opposite working end is pressed into contact with a retainer plate fitted inside the end of the clutch drum of the wet hydraulic multi-plate clutch via a bearing. And the control system of the wet-type hydraulic multi-plate clutch includes an FF drive that transmits power only to the front wheels via one wet-type hydraulic multi-plate clutch, and the other. A switch group is provided to select the driving mode between FR running, which transmits power only to the rear wheels via the wet hydraulic multi-plate clutch, and 4WD running, which transmits power to the front and rear wheels via the wet hydraulic multi-plate clutch. Power distribution device for four-wheel drive vehicles.