JPS62261739A - Power transmitting device - Google Patents

Abstract

PURPOSE:To make automatic on-off switching of torque possible and improve responsiveness by combining an oil pump driven by relative rotation between input and output shafts and a slip type clutch which makes engagement between the input and output shafts by means of discharge pressures of the pump. CONSTITUTION:When slip occurs at a rear wheel, a difference in rpm is produced between an input shaft 13 and a 2nd output shaft 18, and an oil pump 60 is driven by this relative rpm. And since the discharge oil pressure of the pump 60 increases with the relative rpm, the oil pressure in an oil pressure chamber 45 becomes higher, and clutch plates 41 and 42 increase engagement force while they are slipping to distribute torque of an input shaft 13 to the 2nd output shaft 18. As a result, the rpm of the output shaft 18 increases and approaches the rpm of an output shaft 15 to reduce or eliminate the slip at the rear wheel. Since the relative rpm between the output shafts 15 and 18 becomes smaller as the slip is reduced, the discharge pressure of the oil pump 60 is also reduced and transmitted torque is also reduced. Accordingly, tight corner braking is prevented when the relative rpm is small and, at high speeds, fuel economy is improved.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is applicable to power transmission devices that automatically transmit torque according to the relative rotational speed between an input shaft and an output shaft, particularly transfer devices and differentials of four-wheel drive vehicles. The present invention relates to a power transmission device suitable as a restriction device.

BACKGROUND ART Conventionally, viscous couplings have been widely known as a power transmission device that automatically transmits torque according to the relative rotational speed between an input shaft and an output shaft. This viscous coupling consists of alternating discs with many slits fitted into the splines on the shaft side and discs with many round holes fitted into the splines inside the drum. It is made by enclosing viscous silicone oil, and when there is no relative rotation between the input side and output side, no torque is transmitted, but as the relative rotation speed increases, shear resistance between the silicone oil and the disk It is a mechanism for transmitting torque.

The above-mentioned viscous coupling allows extremely smooth power transmission and does not require any switching operations, so for example
When used as a transfer device for a wheel drive vehicle, it can achieve efficient driving similar to a two-wheel drive during normal driving, and fully demonstrate the characteristics of a four-wheel drive when driving on rough or snowy roads.

However, viscous coupling has the following two drawbacks. The first is the torque of the viscous coupling.
The relative rotational speed characteristic shows an upwardly convex curve, and the transmitted torque is relatively large even when the relative rotational speed is small. For example, this may cause tight braking during low-speed cornering, and when there is a difference in rotational speed between the front and rear wheels due to an unbalance in the effective diameter of the front and rear wheels, the product of the relative rotational speed and the transmitted torque The second problem is that the energy loss increases proportionally, which has a negative effect on fuel efficiency, especially in the region of low relative rotation speed when driving at high speeds.
Processing of the disks is complicated and requires high precision, and moreover, a large number of disks are required for one viscous coupling, resulting in high costs.

OBJECTS OF THE INVENTION The purpose of the present invention is to provide a power transmission device that eliminates the drawbacks of the above-mentioned viscous coupling, can transmit torque regardless of the direction of relative rotation between the person and the output shaft, has a simple structure, and has excellent responsiveness. Our goal is to provide the following.

Structure of the Invention In order to achieve the above object, the present invention provides a power transmission device that transmits torque according to the relative rotation speed between the input shaft and the output shaft. Inside a hydraulic pump body that rotates integrally with the input shaft or the output shaft, which is equipped with a rotationally driven hydraulic pump and a sliding clutch that engages the input and output shafts using the discharged hydraulic pressure of the hydraulic pump. A pair of one-way valves having different directions are provided on the discharge side and the suction side of the hydraulic pump.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 shows an example in which the present invention is applied to a transfer device for a four-wheel drive vehicle. Power is distributed to two transmission shafts 4.5. One transmission shaft 4 drives the front wheels 7 via a differential device 6, and the other transmission shaft 5 drives rear wheels 9 via a differential device 8.

FIG. 2 shows the internal structure of the transfer device 3. In the center of the housing 10. A first output shaft 15 is rotatably supported by bearings 16 and 17, and the first output shaft 15 is rotatably supported by bearings 16 and 17.
It is connected to a transmission shaft 5 for driving. Further, a cylindrical second output shaft 18 is attached to a bearing 20 on the outer periphery of the input shaft 13.
．． 21 so as to be relatively rotatable, and the second output shaft 1
A sprocket 22 is spline-coupled to the outer periphery of the right end of the wheel 8, and the sprocket 22 is connected via a chain 23 to a transmission shaft 4 for driving the front wheel 7.

A front case 30 is spline-coupled to the input shaft 13, and a rear case 31 is fitted on the outside of the front case 30, with a cylinder 32 and an oil pump body 33 interposed between them. are joined together by. The internal space of the case 30, 31 is filled with hydraulic oil, and the oil seal 35
．． The filling of the zero hydraulic oil sealed by the bolt 36 is carried out through the bolt insertion hole 31a of the rear case 31. In particular, since the bolt hole 32a of the cylinder 32 has a U-shaped opening on the outer circumferential side, it is difficult to insert the bolt 34. By injecting oil from the bolt insertion hole 31a of the rear case 31 in the pulled out state, the inside of the case 30.31 can be easily filled.

A sliding clutch 40 and an oil pump 60 are connected to the cylinder 32 between the second output shaft 18 and the case 30.31.
They are placed in parallel with each other. That is, a clutch hub 19 is integrally formed at the left end of the second output shaft 18, and a clutch plate 41 is provided between the front case 30 and the clutch hub 19, which are spline-engaged with the front case 30 and the clutch hub 19, respectively. .42 are arranged alternately. The clutch plate 4 is located inside the cylinder 32.
A piston 43 for press-fitting the piston 1.42 is disposed so as to be movable in the axial direction, and the piston 43 is formed with an orifice hole 44 for restricting the flow rate of hydraulic oil leaking from the hydraulic chamber 45. Further, as shown in FIG. 3, a relief valve 46 is provided on the outer peripheral thick part of the cylinder 32, and the hydraulic chamber 46 is provided with a relief valve 46 as shown in FIG.
When the internal pressure of 5 exceeds a predetermined value, it overcomes the spring 47 and opens the drain oil passage 48.49. A cylindrical strainer 50 having a predetermined thickness is arranged on the outer circumferential side of the crassochi plates 41 and 42, and the case 3
0.31 The oil pump 60 is protected by filtering out dirt in the oil circulating inside.

An internal gear type oil pump 60 is provided inside the oil pump body 33 as shown in FIG. is rotatably fitted inside the oil pump body 33. On the inner surface of the rear case 31 facing the oil pump 60, there is a discharge port 63 (which becomes a suction port when the oil pump 60 rotates in the counterclockwise direction in FIG. The oil pump body 33 is provided with a pair of one-way valves 65 and 66 in different directions that communicate with the discharge port 63 and the suction port 64, respectively. . Therefore, hydraulic oil can be discharged to the hydraulic chamber 45 even when the oil pump 60 is driven in either the forward or reverse direction. The hydraulic oil discharged from the oil pump 60 is transferred from the discharge port 63 to the one-way valve 66, the communication hole 32b of the cylinder 32, the hydraulic chamber 45, the orifice hole 44, the clutch plate 41, 42, and the strainer 5 as shown by the arrow in FIG.
0, the oil is circulated through the suction oil passage 67 and the one-way valve 65 to the suction port 64. In particular, since the oil pump 60 sucks hydraulic oil from the outer circumferential side of the case 30, 31, it is affected by centrifugal oil pressure. This solves the problem of air entering the suction port 64 and causing suction failure, and since the suction oil passage is formed in the thin outer peripheral part of the rear case 31,
The hydraulic fluid is effectively cooled.

As mentioned above, the inside of the case 30.31 is almost filled with hydraulic oil, so even if centrifugal hydraulic pressure is generated inside the hydraulic chamber 45 due to the rotation of the case 30.31, the inside and outside of the hydraulic chamber 45 are connected. Since the centrifugal hydraulic pressure is canceled out by the centrifugal hydraulic pressure, there is no problem that the piston 43 engages the clutch plates 41 and 42 as the input rotational speed increases.
Since the clutch plates 41 and 42 are always in oil and the oil is forcibly circulated by the oil pump 60, heat generation of the clutch plates 41 and 42 is suppressed, and deterioration and wear of the clutch plates can be reduced.

In addition, the inside of the case 30.31 has an oil seal 35°3.
6, so there is no risk of oil leaking to the outside.Therefore, this power transmission device is not limited to being installed inside the housing 10.11.12, and even if it is exposed to the outside. There are no problems and there are no restrictions on placement location.

Description of Operation The operation of the power transmission device having the above configuration will be explained. First, front wheel 7
When the rear wheels 9 and 9 are rotating at the same speed, the input shaft 1
3 and the second output shaft 18, the oil pump 60 is not driven at all, and the discharge oil pressure is zero. Therefore, the clutch 40 is not engaged, and the torque of the input shaft 13 is not distributed to the second output shaft 1.

If slip occurs in the rear wheel 9, the input shaft 13
There is a difference in the rotational speed between the first output shaft 15 and the second output shaft 18, and the oil pump 60 is driven according to this relative rotational speed. Since the discharge oil pressure of the oil pump 60 increases in accordance with the relative rotation speed, the oil pressure in the oil pressure chamber 45 increases, and the clutch plates 41 and 42 increase their engagement force while slipping, thereby converting the torque of the input shaft 13 to the second output. distribution to axis 18;

As a result, the rotation speed of the second output shaft 18 increases and approaches the rotation speed of the first output shaft 15, and the slip of the rear wheels 9 is reduced or eliminated.

If the slip of the rear wheel 9 decreases, the relative rotational speed between the first output shaft 15 and the second output shaft 18 decreases, so the discharge oil pressure of the oil pump 60 also decreases, and the transmitted torque decreases.

The torque-relative rotational speed characteristic of the power transmission device of the present invention is the fifth
As shown by the solid line in the figure, it exhibits a downwardly convex quadratic curve characteristic, which is significantly different from the upwardly convex characteristic of the conventional viscous coupling (broken line in Figure 5). In other words, in the case of a viscous coupling, it has a relatively large transmitted torque even when the relative rotational speed is small, so when it is applied to a transfer device, it tends to cause tight corner braking during low-speed cornering, and it also causes problems when driving at high speeds. When the relative rotational speed is relatively small, such as when the vehicle is moving, the energy loss increases in proportion to the product of the relative rotational speed and the transmitted torque, which worsens fuel efficiency, especially during high-speed driving. In contrast, in the present invention, since the transmitted torque is minute when the relative rotational speed is small, it is possible to prevent the tight corner braking phenomenon, and also to reduce energy loss during high-speed driving and improve fuel efficiency.

Although the above embodiment shows a case in which hydraulic oil is sealed in the case and circulated within the case, the present invention is not limited to this, and the hydraulic oil may be supplied to the oil pump from the outside, for example. Further, the power transmission device of the present invention is not limited to one in which the clutch plate, piston, and hydraulic pump are arranged in parallel in this order as in the embodiment, but in the case of the embodiment, the oil passage can be the simplest and shortest, and the response is In addition to improving the properties, the structure becomes more compact.

In addition, although an example of a wet multi-plate clutch mechanism is shown as a slip clutch, a cone clutch mechanism may also be used.
A bellows may be used instead of a piston. Further, the rotary drive type hydraulic pump is not limited to a gear type oil pump, and a vane pump can also be used.

Effects of the Invention As is clear from the above explanation, according to the present invention, there is provided a hydraulic pump driven by the relative rotation of the input and output shafts, and a sliding clutch that engages the input and output shafts by the discharged hydraulic pressure of the hydraulic pump. By combining these, it is possible to automatically switch on and off the torque without inputting any external signals, similar to a viscous coupling, and the transmitted torque is also small when the relative rotational speed of the input and output shafts is small. For,
This solves the problems of viscous couplings such as tight corner braking and poor fuel efficiency when driving at high speeds.

Further, in the present invention, since existing technology can be used for both the hydraulic pump and the slip type clutch, it is possible to provide a product that is less expensive than a viscous coupling and has high reliability.

Furthermore, a pair of one-way valves with different orientations are provided on the discharge and suction sides of the hydraulic pump body, so the hydraulic pump can always discharge working fluid regardless of the direction of relative rotation of the input and output shafts, allowing the clutch to can be activated. In addition, since the oil passage can be made very short, responsiveness is excellent and the structure can be made compact.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a four-wheel drive vehicle to which the present invention is applied;
FIG. 2 is a sectional view of an example of a power transmission device according to the present invention;
Fig. 3 is a partial sectional view of a portion of the above device that is different from Fig. 2, Fig. 4 is a sectional view taken along the line IV-IV in Fig. 2, and Fig. 5 is a comparison diagram of the characteristics of the present invention and a viscous coupling. be. 3... Transfer device, 7... Front wheel, 9... Rear wheel, 13... Input shaft, 15... First output shaft, 18 River second output shaft, 30.31... Case , 32... Cylinder, 33... Oil pump body, 40... Slip type clutch, 41.42... Clutch plate, 43...
・Piston, 44... Orifice hole, 45... Hydraulic chamber, 60... Oil pump, 63... Discharge port, 64
...Suction port, 65.66...One-way valve. Applicant Daihatsu Motor Co., Ltd. Agent Patent attorney Hidetaka Tsutsui ○ Wall (turn) -L-, a)

Claims (1)

[Claims] (1) In a power transmission device that transmits torque according to the relative rotation speed between an input shaft and an output shaft, a rotary drive type hydraulic pump that is driven by the relative rotation between the input shaft and the output shaft; It is equipped with a sliding clutch that engages the input and output shafts using the discharge hydraulic pressure of the hydraulic pump, and is equipped with a sliding clutch on the discharge side and the suction side of the hydraulic pump, inside the hydraulic pump body that rotates integrally with the input shaft or output shaft. A power transmission device characterized by having a pair of one-way valves each oriented in a different direction.