JPH0449376Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention mainly relates to improvements in power transmission devices for automobiles, and particularly in power transmission devices that transmit power from a power transmission mechanism having an output shaft to a propeller shaft or the like.

(Prior art) As an automobile power transmission mechanism, for example,
As described in Publication No. 157930, there is a known 2-4 wheel drive switching device for 4-wheel drive vehicles that allows engine output to be output not only to the rear wheels but also to the front wheels as needed. It is being This type of power transmission mechanism generally has an output shaft 2 rotatably supported within a housing 1, as shown in FIG. 6, and a propeller shaft 4 having a yoke shaft 3 at one end is connected to the output shaft 2. However, in that case, the yoke shaft 3 is made hollow and the output shaft 2
Generally, the yoke shaft 3 and the output shaft 2 are spline-coupled by splines 3a and 2a formed on the inner and outer peripheral surfaces of the yoke shaft 3 and the output shaft 2, respectively. An oil seal 5 is attached to the protrusion of the output shaft 2 in the housing 1, and the oil seal 5 slides on the outer peripheral surface of the yoke shaft 3 fitted onto the output shaft 2. Constructed to prevent leakage.

According to such a configuration, when power is transmitted to the output shaft 2 and the shaft 2 is rotated, the yoke shaft 3 spline-coupled thereto is rotated integrally with the output shaft 2. Power will be taken out to the propeller shaft 4. In this case,
For example, when the propeller shaft 4 is a 2-wheel-4-wheel drive switching device in a 4-wheel drive vehicle shown in the above-mentioned publication and is connected to the front wheel drive shaft, The propeller shaft 4 is moved in the axial direction in relation to the relative vertical movement of the front wheels, and along with this, the yoke shaft 3 attached to one end of the propeller shaft 4 is also rotated in the axial direction. I will have to move. Therefore, the oil seal 5 mounted on the housing 1 and the outer peripheral surface of the yoke shaft 3 slide simultaneously in the rotational direction and axial direction of the shaft 3, resulting in wear of the oil seal 5. This causes problems such as shortening of lifespan.

(Purpose of the invention) The present invention addresses the above-mentioned problems in the connection between the output shaft of a power transmission mechanism and a power transmission shaft such as a propeller shaft having a yoke shaft at one end. By preventing the oil seal attached to the protrusion of the output shaft in the housing from sliding in the rotational direction and the axial direction at the same time, the durability of the oil seal is improved. The purpose is to prevent foreign matter from entering the mounting portion and the spline fitting portion between the output shaft and the yoke shaft.

(Structure of the invention) In order to achieve the above object, the power transmission device according to the invention is structured as follows.

That is, a power transmission mechanism includes an output shaft that is rotatably supported within a housing and has one end protruding from an opening provided in the housing, and a power transmission shaft that has a yoke shaft connected to the output shaft at one end. In the power transmission device, the output shaft is hollow, and the yoke shaft is fitted inside the output shaft. Then, the two shafts are connected by splines provided on the inner circumferential surface of the output shaft and the outer circumferential surface of the yoke shaft, and an oil seal that slides on the outer circumference of the output shaft is installed in the opening in the housing. is provided with a dust cover having one end fixed to the yoke shaft and the other end extending toward the opening side of the housing to cover the mounting portion of the oil seal from the outside, and further includes a dust cover and an oil seal on the output shaft. A sealing member for preventing dust intrusion is installed between the sliding contact portion and the outer peripheral surface on the yoke shaft side.

According to such a configuration, when power is transmitted to the output shaft and the shaft is rotated, the power is transmitted to the power transmission shaft via the yoke shaft fitted therein and spline-coupled. Become. Further, in the case where the power transmission shaft is connected to a front wheel drive shaft of a four-wheel drive vehicle, for example, the power transmission shaft is moved in the axial direction by the vertical movement of the front wheels, and at this time, The yoke shaft is moved in the axial direction while rotating integrally with the output shaft. However, even in such a case, the output shaft does not move in the axial direction, so the oil seal that is in sliding contact with the outer circumferential surface of the output shaft slides only in the rotational direction with respect to the outer circumferential surface of the shaft. That will happen. Further, according to the above configuration, one end of the dust cover is fixed to the yoke shaft and the other end of the dust cover covers the oil seal mounting portion from the outside, so that foreign matter is prevented from entering the oil seal mounting portion. Furthermore, the sealing member installed between the dust cover and the output shaft outer circumferential surface allows
The spline fitting portion between the output shaft and the yoke shaft is sealed from the outside.

(Effect of the invention) According to the invention as described above, in the power transmission device in which the yoke shaft attached to one end of the power transmission shaft is spline-coupled to the output shaft of the power transmission mechanism, The oil seal attached to the protrusion of the output shaft comes into sliding contact with the outer circumferential surface of the output shaft that does not move in the axial direction, thereby preventing it from sliding in the rotational direction and the axial direction at the same time. As a result, the load on the oil seal is significantly reduced compared to the case where the oil seal slides in the rotational direction and the axial direction simultaneously, and in particular, one end of the mounting portion of the oil seal is fixed to the yoke shaft The oil seal is protected by a dust cover that prevents foreign matter from entering from the outside, thereby preventing premature wear of the oil seal and improving durability. Furthermore, since the spline fitting portion between the output shaft and the yoke shaft is sealed from the outside by a sealing member for preventing dust intrusion, foreign matter is prevented from entering or getting caught in the fitting portion, and the spline The durability of the fitting portion will also be improved.

(Example) Next, a specific example of the present invention will be described based on the drawings.

FIG. 1 is a front view showing the appearance of a power line section in a four-wheel drive vehicle having a two-wheel-to-four-wheel drive switching device, which is an example of a power transmission device according to the present invention. Shion 1
2, where the gear is changed according to the operation of the gear shift lever 13, and then the two-wheel-four-wheel drive switching device 14
It is now entered into . Also, the engine 1 input to this two-wheel-four-wheel drive switching device 14
The output of transmission 1 or transmission 12 is for two wheels.
By operating the four-wheel drive switching lever 15,
The output is switched to two-wheel drive or four-wheel drive as needed.

In other words, this two-wheel-four-wheel drive switching device 14 is
As shown in FIG. 2, there is a drive shaft 19 that is integrally or directly connected to the output shaft of the transmission 12 and rotatably supported by a pair of housings 16 and 17 by bearings 18a and 18b, and a lower part of the drive shaft 19. bearings 20a, disposed parallel to the shaft 19 and within the housings 16, 17;
Output shaft 21 rotatably supported via 20b
In addition, a drive gear 22 is loosely fitted to the drive shaft 19, and a driven gear 23 is integrally formed with the output shaft 21, and a chain 24 is wound between both gears 22 and 23. . Further, an engaging portion 22a having a spline on the outer periphery is formed on the side of the drive gear 22, and a hub 25 having a spline with the same specifications as the spline on the outer periphery is attached to the drive shaft 19. Drive gear 22
It is fitted and fixed on the side. A sleeve 26 is spline-fitted to the outer circumference of the hub 25, and a shift fork 27 is engaged with a circumferential groove 26a formed on the outer circumference of the sleeve 26. By moving the sleeve 26 in the axial direction in conjunction with the two-wheel/four-wheel drive switching lever 15, the sleeve 26 changes from spline-fitting only to the hub 25 as shown in the figure to the hub 25 and the drive gear 22. The spline-fitting state can be switched to a spline-fitted state across the engaging portion 22a. This creates a two-wheel drive state in which the output of the engine 11 or transmission 12 is transmitted only to the rear wheels by the drive shaft 19 via the rear yoke 29 attached to the rear end, and furthermore, the drive shaft 1
9, the drive gear 22, the chain 24, and the output gear 23 are connected to the hub 25, the sleeve 26, the drive gear 22, the chain 24, and the output gear 23.

As shown in FIGS. 2 and 3, one end of the output shaft 21 projects outward from a cylindrical wall 16a provided on the housing 16, and a differential gear (not shown) and a differential gear (not shown) are attached to the projecting portion. A propeller shaft 30 that transmits power to the left and right front wheels via a front wheel drive shaft is connected. Next, the structure of the connecting portion between the propeller shaft 30 and the output shaft 21 will be described. A yoke shaft 32 having a spline formed on the outer periphery is attached to one end of the propeller shaft 30 via a universal joint 31. On the other hand, the output shaft 21 is internally spaced and has a spline formed on its inner peripheral surface. Then, the yoke shaft 32 is fitted into the output shaft 21 and the two are spline-coupled, so that the output shaft 21 and the yoke shaft 32 or the propeller shaft 30 are connected to each other.
The yoke shaft 32 rotates integrally with the yoke shaft 32 and is connected to the yoke shaft 32 so as to be slidable in the axial direction.

In addition, this output shaft 21 and propeller shaft 30
An oil seal 33 is installed inside the cylindrical wall 16a of the housing 16 at the connection portion with the output shaft 21, and the seal 33 is in sliding contact with the outer peripheral surface of the output shaft 21. The yoke shaft 32 includes:
A cylindrical dust cover 37 is attached, one end of which is fixed to the yoke shaft 32, and the other end of which extends to the outside of the tip opening of the cylindrical wall 16a to cover the mounting portion of the oil seal 33 from the outside. Further, the output shaft 2 is attached to the dust cover 37.
A seal member 38 for preventing dust intrusion is attached to the outer circumferential surface of the output shaft 21 on the side closer to the yoke shaft 32 than the sliding contact portion of the oil seal 33 in FIG.

According to the above configuration, by operating the 2-wheel-4-wheel switching lever 15 to the 4-wheel drive side as described above, the engine 11 or the transmission 12
The output is transmitted to the output shaft 21 to rotate the shaft 21, and the propeller shaft 30 is also rotated via the yoke shaft 32 fitted therein and spline-coupled, thereby driving the front wheels. It becomes a four-wheel drive state.

However, when the front wheels relatively move up and down while being driven in this manner, the propeller shaft 30 is moved in the axial direction, and at this time, one end of the propeller shaft 30 The yoke shaft 32 of the output shaft 21 rotates integrally with the output shaft 21 and is moved in the axial direction within the output shaft 21. However, even in such a case, the output shaft 21 and the yoke shaft 32 are slidably spline-coupled, and the output shaft 21 is connected to the bearing 2.
Since it is supported by the housings 16 and 17 via 0a and 20b, the output shaft 21 is not moved in the axial direction in conjunction with the axial movement of the yoke shaft 32. Therefore, the cylindrical wall 16 of the housing 16
The oil seal 33 attached to the output shaft 21 in sliding contact with the outer circumferential surface of the output shaft 21 keeps the output shaft 2
The oil seal 33 is slid against the outer circumferential surface of the oil seal 33 only in the rotational direction, thereby reducing the burden on the oil seal 33. Furthermore, since one end of the oil seal 33 is covered from the outside by a dust cover 37 fixed to the yoke shaft 32, it is protected from foreign matter entering from the outside. Early wear of the oil seal 33 is effectively prevented. Furthermore, the dust cover 37 has an oil seal 3 on the output shaft 21.
Since a sealing member 38 for preventing dust intrusion is attached to the outer circumferential surface on the tip side from the sliding contact portion of No. 3, the spline fitting portion between the output shaft 21 and the yoke shaft 32 is sealed from the outside. This will prevent foreign matter from entering or getting caught in the fitting portion.

In addition, according to the above configuration, in addition to the effect of reducing the wear of the oil seal 33 and the effect of preventing the intrusion of foreign matter,
The effect of improving productivity during assembly can be obtained. In other words, in the conventional structure shown in FIG. 6, the power transmission mechanism (2-wheel-4-wheel drive switching device) is assembled as a single unit, that is, the yoke shaft 3 is not spline-fitted to the output shaft 2. Housing 1 in condition
When lubricating oil is injected into the output shaft 2, since there is no yoke shaft 3 that comes into sliding contact with the oil seal 5, the lubricating oil flows out from between the oil seal 5 and the output shaft 2. Therefore, in this case, it is necessary to install a cap member that closes the gap between the oil seal 3 and the output shaft 2, and then inject lubricating oil. On the other hand, according to the configuration of the present invention, even if the yoke shaft 32 is not fitted, the oil seal 33 is in sliding contact with the outer peripheral surface of the output shaft 21, so that as shown in FIGS. By closing the rear end side of the hollow part of the output shaft 21 in advance with a plug 39, or by forming the hollow part so as not to penetrate to the rear end side, the housings 16 and 17 can be made airtight from the outside. can do. Therefore, lubricating oil can be injected without using a cap member as in the conventional case.

In the above embodiment, as shown in an enlarged view in FIG. the main lip 34, which is also in sliding contact with the outer peripheral surface of the output shaft 21, and prevents foreign substances such as dust and water from entering the housings 16, 17.
5b, and a dust cover fixed to the yoke shaft 32 by extending a core metal 36 in the circumferential direction and bending its tip in the axial direction for the purpose of reinforcing the oil seal 33. 37 to more effectively prevent foreign matter from entering from the outside.

Further, in the embodiment shown in FIG. 5, the output shaft 21' is supported in the housings 16', 17' via bearings 20a', 20b' before and after the driven gear 23', as in the above embodiment. In addition, the front portion of the shaft 21' is also supported via a bearing 40' immediately behind the oil seal 33' on the cylindrical wall 16a'. As a result, the output shaft 2
This is intended to prevent vibration during rotation of the oil seal 33' and avoid adverse effects on the oil seal 33'.

Note that the present invention is not limited to the two-wheel-to-four-wheel drive switching device in a four-wheel drive vehicle as shown in the above embodiment, but also applies to the connection between the output shaft of a transmission and a propeller shaft in a front engine-rear drive vehicle, and furthermore, can also be widely applied to other power transmission mechanisms with similar configurations.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a front view showing the appearance of a power line section in a four-wheel drive vehicle having a two-wheel-to-four-wheel drive switching device, which is an example of a power transmission device. The figure is an enlarged cross-sectional view of the 2-wheel-4-wheel drive switching device in Figure 1,
4 is an enlarged sectional view of a part of an oil seal used in the present invention, and FIG. 5 is an enlarged sectional view of an essential part showing another embodiment. Also,
FIG. 6 is a sectional view of a main part showing a conventional example. 14... Power transmission mechanism (2-wheel-4 wheel drive switching device), 16, 17... Housing, 16a... Opening (cylindrical wall), 21... Output shaft, 30... Power transmission shaft (propeller shaft) ), 32... Yoke shaft,
33...Oil seal, 37...Dust cover,
38... Seal member for preventing dust intrusion.

Claims (1)

[Scope of utility model registration request] A power transmission mechanism having an output shaft rotatably supported within a housing and having one end protruding outward from an opening provided in the housing, and a power transmission mechanism having a yoke shaft connected to the output shaft at one end. A power transmission device consisting of a shaft, wherein the output shaft is hollow, the yoke shaft is fitted inside the output shaft, and both have splines formed on their inner and outer peripheral surfaces. combined by
On the other hand, an oil seal is installed in the opening of the housing so as to be in sliding contact with the outer peripheral surface of the output shaft, and one end of the yoke shaft is fixed to the yoke shaft, and the other end is attached to the opening of the housing. A dust cover is provided that extends to cover the mounting portion of the oil seal from the outside, and is provided between the outer circumferential surface of the output shaft on the yoke shaft side with respect to the sliding contact portion of the oil seal and the dust cover to prevent dust from entering. A power transmission device characterized by being equipped with a sealing member.