JPS62253531A - Power transmitting device - Google Patents

Abstract

PURPOSE:To prevent a slip at the time of quick advancing or quick braking by providing an orifice hole so that a mass body is moved in the longitudinal direction of a vehicle and restricting the liquid quantity leaking from the orifice hole with the longitudinal acceleration. CONSTITUTION:When the large longitudinal acceleration is applied to a vehicle, a mass body 52 arranged on the inner periphery of a cylinder 32 is moved in the longitudinal direction against springs 54, 55 and squeezes the opening of an orifice hole 51 to decrease the oil leakage quantity. Thereby, a clutch 40 is firmly engaged by even the slight discharge oil pressure of an oil pump 60. That is, a four-wheel driving condition is automatically attained before a slip is generated by detecting the longitudinal acceleration. Accordingly, a slip is decreased at the time of quick advancing, and an anti-skid effect can be attained at the time of quick braking.

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 filled with viscous silicone oil, and when there is no relative rotation between the input side and the output side, no torque is transmitted, but as the relative rotation speed increases, the torque is transmitted due to the shear resistance between the silicone oil and the disc. It is a mechanism for communicating.

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. This term means that, for example, when tight braking is likely to occur during low-speed cornering, or 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 The second reason is that the energy loss is large (because of this, it 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.

OBJECT OF THE INVENTION The object of the present invention is to provide a power transmission device that eliminates the drawbacks of the viscous coupling described above, prevents slips during sudden starts and sudden braking, and provides steering stability when climbing and descending. 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. It is equipped with a hydraulic pump to be driven and a sliding clutch that engages input and output shafts by the discharge hydraulic pressure of the hydraulic pump, and the sliding clutch is provided with an orifice hole for clutch hydraulic pressure control, A mass body capable of adjusting the opening area of the orifice hole is provided so as to be movable in the longitudinal direction of the vehicle, so that the amount of liquid leaking from the orifice hole can be limited by the longitudinal acceleration of the vehicle.

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. A transmission 2 is connected to the rear of an engine 1, and the output of the transmission 2 is transmitted through a transfer device 3. The power is distributed to two transmission shafts 4.5. and,
One transmission shaft 4 drives the front wheels 7 via a differential device 6,
The other transmission shaft 5 drives rear wheels 9 via a differential gear 8.

FIG. 2 shows the internal structure of the transfer device 3. In the center of the housing 10. The first output shaft 15 is rotatably supported by a bearing 16.17, and the first output shaft 15 is connected to the rear wheel 9.
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 3o is spline-coupled to the input shaft 13, and a rear case 31 is fitted on the outside of the front case 3o, 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
, 36. The filling of hydraulic oil 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 is about to open in a U-shape on the outer circumferential side, the bolt of the rear case 31 is filled with the bolt 34 with the bolt 34 pulled out. By injecting oil through the insertion hole 31a, 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 that presses the cylinder 32 is disposed so as to be movable in the axial direction, and a hydraulic chamber 45 is formed between the piston 43 and the cylinder 32.

An orifice hole 51 for controlling the clutch hydraulic pressure is formed in the inner circumferential portion of the cylinder 32 facing the hydraulic chamber 45, and a cylindrical mass is provided on the inner circumferential side of the orifice hole 51 as shown in FIG. A body 52 is disposed to be movable in the axial direction (vehicle longitudinal direction), and both front and rear ends of the mass body 52 are elastically supported by springs 54 and 55. A communication hole 53 having a larger diameter than the orifice hole 51 is formed in a portion of the mass body 52 corresponding to the orifice hole 51. When the longitudinal acceleration of the vehicle is zero or slight, the orifice hole 5
1 corresponds to the communication hole 53, so the amount of oil leaking from the hydraulic chamber 45 is maximum, and when a large longitudinal acceleration is applied, the orifice hole 51 and the communication hole 53 are misaligned, and the amount of oil leaking from the hydraulic chamber 45 is maximized. The amount of leaked oil is reduced.

Further, as shown in FIG. 4, a relief valve 46 is provided in the thick outer circumference of the cylinder 32, and when the internal pressure of the hydraulic chamber 45 exceeds a predetermined value, it overcomes the spring 47 and closes the drain oil passages 48, 49. It is designed to open. A cylindrical strainer 50 having a predetermined thickness is arranged on the outer peripheral side of the clutch plate 41.42, and the case 30.31
The oil pump 60 filters dirt in the oil circulating inside.
is protected.

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 counterclockwise 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 transmitted from the discharge port 63 to the one-way valve 66, the communication hole 32b1 of the cylinder 32, the hydraulic chamber 45, the orifice hole 51, the communication hole 53, and the clutch plate 41, 42, as shown by the arrow in FIG. The oil is circulated through the strainer 50, suction oil passage 67, and 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, the centrifugal hydraulic pressure is This solves the problem of air entering the suction port 64 and causing poor suction, and since the suction oil passage is formed in the thin outer peripheral portion of the rear case 31, the hydraulic oil 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 offset by , there is no problem of the piston 43 erroneously engaging the clutch plate 4L42 as the input rotational speed increases. Also, clutch plate 41.4
2 is always in oil, and the oil is forcibly circulated by the oil pump 60, so heat generation of the clutch plate 4L42 is suppressed, and deterioration and wear and tear of the clutch plate 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 18.

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 I8.

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 sixth
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 6). In other words, in the case of a viscous coupling, it has a relatively large transmission torque even when the relative rotational speed is small, so if it is used in a transfer device, it is likely to cause tight corner braking during low-speed cornering, and it will be difficult to drive 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.

By the way, when starting suddenly or braking suddenly, the wheels tend to slip or skid, and when climbing or descending, the shared load between the front and rear wheels becomes unbalanced, resulting in poor steering stability. It is necessary to switch to the driving state. In the present invention, when a large longitudinal acceleration is applied to the vehicle, the mass body 52 disposed in the inner part of the cylinder 32 moves in the longitudinal direction against the spring 54, 55, narrowing the opening of the orifice hole 51 and causing oil leakage. In order to reduce the amount of oil pressure discharged from the oil pump 60, the clutch 40
can be strongly engaged. In other words, since the vehicle can sense longitudinal acceleration and automatically enter the four-wheel drive state before slippage actually occurs, it is possible to reduce slippage during sudden starts and achieve an anti-skid effect during sudden braking. Moreover, since the mass body 52 moves back and forth even when climbing up or descending from the platform, the vehicle can be in a four-wheel drive state, thereby increasing steering stability.

In the above embodiment, an example was shown in which the orifice hole was provided in the cylinder, but it can also be provided in the piston, for example, as long as it is on the wall surface facing the hydraulic chamber. Therefore, the shape and location of the mass body are not limited to the above embodiments.

The power transmission device of the present invention is not limited to a case in which hydraulic oil is sealed in a case and circulates within the case, and the hydraulic oil may be supplied to the oil pump from the outside. In addition, although we have shown an example of a wet multi-plate clutch mechanism as a slip clutch, a cone clutch mechanism may also be used, and the hydraulic pump is not limited to a gear type oil pump, but also a vane pump or a piston pump. .

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, when acceleration is applied to the vehicle in the longitudinal direction, the mass body squeezes the orifice hole so that the clutch can be easily engaged, so when the present invention is applied to a transfer device,
It can sense the longitudinal acceleration of the vehicle and automatically switch to 4-wheel drive before actual slip occurs, reducing slip when starting suddenly, achieving anti-skid effect during sudden braking, and when climbing or descending from the vehicle. It is possible to improve fi11 stability.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a four-wheel UA 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, and FIG. 3 is a partially enlarged view of FIG. Fig. 4 is a partial sectional view of a portion of the above device that is different from Fig. 2, Fig. 5 is a sectional view taken along the line V-V in Fig. 2, and Fig. 6 is a comparison diagram of the characteristics of the present invention and the viscous coupling. be. 3... Transfer device, 7... Front wheel, 9... Rear wheel, 13... Input shaft, 15... First output shaft, 18...
...Second output shaft, 30.31...Case, 32...
Cylinder, 33...Oil pump pod, 40...
Slip type clutch, 41.42...Clutch plate, 43
... Piston, 45 ... Hydraulic chamber, 51 ... Orifice hole, 52 ... Mass body, 53 ... Communication hole, 54.
55...Spring, 60...Oil pump, 63
...Discharge port, 64...Suction port, 65.66...One-way valve. Applicant Daihatsu Motor Co., Ltd. Agent Patent Attorney Hidetaka Tsutsui To Figure 4 Figure 5: rYe Figure

Claims (1)

[Claims] (1) In a power transmission device that transmits torque according to the relative rotation speed between the input shaft and the output shaft, there is a hydraulic pump driven by the relative rotation between the input shaft and the output shaft, and the hydraulic pump. a sliding clutch that engages between input and output shafts by discharged hydraulic pressure, the sliding clutch is provided with an orifice hole for clutch hydraulic pressure control, and a mass body capable of adjusting the opening area of the orifice hole. What is claimed is: 1. A power transmission device, characterized in that it is movable in the longitudinal direction of a vehicle, and is capable of limiting the amount of liquid leaking from an orifice hole depending on the longitudinal acceleration of the vehicle.