JPH08320060A - Differential device - Google Patents

Abstract

PURPOSE: To provide a differential device in which dust or moisture is not taken into a lip part of an oil seal. CONSTITUTION: A cylindrical surface 12A formed on a torque converter housing 12 and a cylindrical surface 11A formed on a drive shaft 11 are faced to each other in the outward position in the axial direction from an oil seal 21C and overlapped in the axial direction. The oil seal 21C is arranged in such a position as not to be directly seen from the outside through the clearance between the cylindrical surfaces 11A, 12B. Since only the drive shaft 11 can be pulled out in the axial direction by loosening a through bolt 16 without disassembling the parts on the periphery, work efficiency in the assembly is improved, and replacement of the oil seal 21C can be easily performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential device for driving left and right moving wheels so that they can rotate relative to each other.

[0002]

2. Description of the Related Art A horizontal type automatic transmission that drives front wheels may incorporate a differential device integrally. The differential device drives the left and right moving wheels so that they can rotate relative to each other, and absorbs a difference in rotation speed between the inner and outer wheels due to steering of the vehicle. The differential device includes a pair of drive shafts that transmit driving force to the left and right driving wheels, respectively.
A differential case that holds a pair of drive shafts so that they can rotate relative to each other, with a built-in gear mechanism that interlocks a pair of drive shafts, and the gear case of the differential case is placed in a position that sandwiches the gear mechanism in the axial direction. It has a pair of bearing devices that rotatably hold it, and a seal device that is attached to the housing to rotatably seal the drive shaft and separates the differential case and the bearing device inside the housing.

An example of an automatic transmission incorporating a differential device is "Workshop Manual Pas".
sat 1988 (Volkswagen), Chapter 39, paragraph 41, Figures 39-1381, and Kaikaihei 7-126.
No. 50 publication. In the former, a conical gear (bevel gear) connected to the driving wheel of the gear mechanism is fixed to the drive shaft by fitting a pair of snap rings to the drive shaft inside and outside the differential case.

In the latter case, a conical gear (bevel gear) connected to the driving wheel of the gear mechanism is fixed to the drive shaft by a through bolt that penetrates the drive shaft in the axial direction. The conical gear has a spline that meshes with the spline of the drive shaft.A female screw member that strikes the surface of the conical gear on the opposite side of the drive shaft and limits the axial movement of the conical gear is stored in the differential case, and the through bolt is inserted. To fix. Here, since the protrusion that meshes with the drive shaft in common with the spline of the conical gear is formed in the female screw member to restrain the rotation of the female screw member, unlike the former, a differential case or a gear mechanism is provided in the housing. After assembly, the drive shaft can be inserted from the outside and assembled with through bolts.

[0005]

In the differential device, the seal device is provided between the housing and the drive shaft to isolate the differential case and the bearing device from each other inside the housing. Therefore, if the seal device is damaged, There is a possibility that dust and water may get inside and rust or damage the precision finishing surface and sliding surface of the mechanism. Here, since the sealing device assumes normal environmental conditions and life,
If the bonnet is flooded by operating in a desert area or a sandy beach for a long time, crossing a river, or suffering water damage, the sealing device may be damaged by being exposed to more severe conditions than usual. is there.

Further, in the above-mentioned two conventional examples, since the flange portion for connecting the shaft on the driving wheel side to the drive shaft is formed in a bowl shape, sand and water are sealed along the slope of the bowl shape. There is a possibility of being guided to the lip part of. In addition, the structure allows the sealing device to be viewed directly from the annular gap between the flange and the housing, so particles that fly up in the hood due to vibration of the vehicle body can jump directly into the contact surface between the lip of the sealing device and the drive shaft. There is also a nature. However, in order to prevent these, if the bowl-shaped flange is moved to the outside in the axial direction, or if a collar or groove is formed on the outside of the seal device of the drive shaft, the overall axial length will increase. However, the mountability on the vehicle body will be impaired.

According to the present invention, the sealing device is less likely to be damaged even when exposed to harsh conditions, and even when the flange portion and the axial length of the conventional structure are adopted, the contact surface between the lip portion and the drive shaft is It is an object of the present invention to provide a differential device in which dust and water do not directly enter.

[0008]

According to a first aspect of the present invention, a pair of drive shafts for transmitting a driving force to the left and right driving wheels, respectively, and a gear mechanism for interlocking the pair of drive shafts are built into the pair of drive shafts. A differential case that holds the drive shaft rotatably relative to each other; and a pair of bearing devices that are arranged at positions that sandwich the gear mechanism of the differential case in the axial direction and that rotatably hold the entire differential case with respect to the housing. A differential device that is attached to the housing, rotatably seals the drive shaft, and has a seal device that isolates the differential case and the bearing device inside the housing, wherein An inner cylindrical surface surrounding the drive shaft on the outer side in the direction An outer peripheral rotating surface that faces the surface via a narrow gap and overlaps in the axial direction on the drive shaft, and at least the lip portion of the sealing device cannot be directly viewed from the gap between the inner cylindrical surface and the outer peripheral rotating surface. It was done.

According to a second aspect of the present invention, in the differential device according to the first aspect, the inner cylindrical surface and the outer peripheral rotating surface are parallel cylindrical surfaces each having a diameter larger than a lip portion of the sealing device. The drive shaft is prevented from interfering with each other when the drive shaft is moved in the axial direction with respect to the housing.

According to a third aspect of the present invention, in the differential device according to the second aspect, the gear mechanism abuts against the conical gear from a center of the differential case and a conical gear having a spline that meshes with a spline of the drive shaft. The internal surface of the differential case to limit the axial movement of the conical gear, and a thread for axially penetrating the drive shaft and fixing the female screw member to the drive shaft. The female screw member is formed with a protrusion having a bolt and meshing with the spline of the conical gear in common with the drive shaft.

[0011]

In the differential device according to the first aspect of the present invention, the inner cylindrical surface on the housing side and the outer peripheral rotating surface on the drive shaft side overlap in the axial direction through a narrow gap to directly influence the external environment on the sealing device. Alleviate. That is, unlike the two conventional differential devices described above,
At least the lip portion of the sealing device cannot be directly viewed from the outside through the gap between the drive shaft (flange portion) and the housing. As a result, there is no concern that sand dust or water scattered in the bonnet will directly enter the lip surface of the sealing device and the sliding surface of the drive shaft or its vicinity.

In the differential device according to the second aspect, since the inner cylindrical surface and the outer peripheral rotating surface are parallel cylindrical surfaces, when the drive shaft and the housing are axially adjusted in position or axially attached and detached, The cylindrical surface does not interfere with the outer peripheral rotating surface.

In the differential device according to the third aspect of the present invention, since the rotation of the female screw member is constrained to the drive shaft on the opposite side from the conical gear through the gear mechanism, the gear mechanism and the differential case are assembled into the housing, and then from the outside. , Drive shaft can be installed or removed. With the configuration in which the drive bolt can be removed by loosening the through bolt from the outside, it is possible to replace the bearing device and the seal device by inserting a tool from the space occupied by the drive shaft.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A differential device of an embodiment will be described with reference to FIGS. FIG. 1 is a sectional view of a differential device incorporated in an automatic transmission, FIG. 2 is an enlarged view of an oil seal mounting portion, and FIG. 3 is a partial enlarged view of a differential case. The differential device shown in FIG. 1 is a part of a horizontal type automatic transmission that is arranged directly on an engine of a hood of a passenger car. And, except for a part of the housing and the drive shaft, the actual flat plate 7-126
It has substantially the same structure and function as the device shown in Japanese Patent Laid-Open No. 50.

The housing of the differential device occupies a part of the housing of the automatic transmission, and is constructed by connecting a transmission housing 10 on the right side of the drawing to a converter housing 12 on the left side of the drawing. A differential case 17 accommodating a gear mechanism is provided inside the casing with bearing devices 22A and 2A.
It is rotatably held by 2B. The gear mechanism includes conical gears 13 and 14, an internal thread member 15, a shaft 18, and the like. The position on the left side of the differential case 17, which sandwiches the gear mechanism, is supported by the converter housing 12 by the bearing device 22A, and the position on the opposite side is the bearing device 22B.
Is supported by the transmission case 10.
The entire differential case 17 is rotationally driven by an output gear (not shown) of the automatic transmission via a final gear 19 attached to the right side portion. The gear 23 attached to the left side portion of the differential case 17 drives a pinion gear (not shown) meshing with the gear 23. The vehicle speed is detected from the output of a magnetic sensor that measures the rotation angle of this pinion gear.

The central gear mechanism has a pair of left and right conical gears (bevel gears) 14 and a pair of upper and lower conical gears (bevel gears) 13 in the figure.
Is linked with. The pair of conical gears 13 is rotatably supported by a shaft 18 fixed to a differential case 17. The left conical gear 14 is fixed to the drive shaft 11 by using a through bolt 16 and a female screw member 15, as shown in detail in FIG. The male screw 16A formed at the tip of the through bolt 16 is replaced with the female screw 15A of the female screw member 15.
Fixed to. The drive shaft 11 is urged outward by a spring 24 shown in FIG. 1, and the conical gear 14 is pulled outward through the female screw member 15 and pressed against the side washer 27 so that the conical gear 14 in the differential case 17 is pushed. Position 14 axially.

A spline 14S is formed on the conical gear 14. The spline 11S formed on the drive shaft 11 and the protrusion 15S formed on the female screw member 15 mesh with the spline 14S in common. The conical gears 13, 14, the shaft 18, the female screw member 15 and the like are assembled in the differential case 17 through openings (not shown) formed on the front side and the back side of the differential case 17 shown in FIG.

An end portion of the spring 24 on the differential case 17 side is a spring retainer 24R shown in FIG.
The cone ring 25 is pushed into the conical surface formed on the differential case 17 via. Cone ring 25
Holds the drive shaft 11 rotatably and attaches the drive shaft 11 to the differential case 1.
Position on the center line of 7.

An oil seal 21C attached to the converter housing 12 seals the periphery of the drive shaft 11. The oil seal 21C cooperates with the oil seal 21D attached to the transmission case 10 to isolate the precision machine component inside from the external environment. Differential case 17, bearing devices 22A, 22B,
In addition to the cone ring 25, the entire transmission mechanism (not shown) that transmits power to the final gear 19 includes an oil seal 21.
Protected from external dust and water by C and 21D.

As shown in detail in FIG. 2, the oil seal 21C is inserted into the cylindrical surface formed on the converter housing 12 to slide the lip portion 21A on the cylindrical surface formed on the drive shaft 11. The configuration described so far is almost the same as that of the device disclosed in Japanese Utility Model Laid-Open No. 7-12650, but in the present embodiment, in addition to this, a protector portion A (opposed cylindrical surface 11A) is provided outside the oil seal 21C. , 12A). In the following, the protector portion A provided on the oil seal 21C on the torque converter housing 12 side will be mainly described, but in the present embodiment, as shown by being surrounded by a broken line in FIG.
Oil seal 21D on the transmission case 10 side
A similar protector is also formed on the outside of.

The protector portion A is formed by axially overlapping a cylindrical surface 12A formed on the end of the converter housing 12 and a cylindrical surface 11A formed on the drive shaft 11. Moreover, since the cylindrical surface 11A is formed by enlarging the diameter of the cylindrical surface of the drive shaft 11 on which the lip portion 21A of the oil seal 21C slides, the lip portion from the outside through the gap between the cylindrical surfaces 11A and 12A. Not only 21A but also a part of the oil seal 21C cannot be directly looked at. Also, the diameter D of the cylindrical surface 11A
1 is set to about 98% of the diameter D2 of the cylindrical surface 12A,
A gap of about 0.7 mm is secured between the cylindrical surface 11A and the cylindrical surface 12A.

According to the differential device of the embodiment,
Providing a protector section A, let alone the lip section 21A,
Since the oil seal 21C is configured so that it cannot be directly viewed from the outside, dust and water on the outside can prevent the oil seal 21C from seeing.
Directly affects the rubber material and deteriorates the lip portion 2
It is less likely that the drive shaft 11 adjacent to 1A will be attached to the drive shaft 11 and caught in the lip portion 21A. Therefore, the life of the sealing device 21C is extended, and even under severe operating conditions and long-term use, the transmission case 10
The parts of the differential device held in the inner space of the converter housing 12 are maintained in a new condition without any rust or damage.

Further, when assembling or transporting the automatic transmission, there is no risk of damaging the oil seal 21C by mistakenly inserting a tool or packing material into the gap between the converter housing 12 and the drive shaft 11. Further, the cylindrical surface 12A of the converter housing 12 also functions as a surface for centering and guiding the insertion arm of the assembly machine when the oil seal is automatically assembled to the converter housing 12.

Further, since the protector portion A is constituted by the opposing cylindrical surfaces 11A and 11B so that the drive shaft 11 does not interfere with the converter housing 12 when the drive shaft 11 is attached or detached in the axial direction, Similar to the device disclosed in Kaihei 7-12650, the degree of freedom in the entire assembling procedure is increased, and the assembling of the automatic transmission can be efficiently performed. Further, since a bowl-shaped flange portion for connecting the shaft on the driving wheel side is formed integrally with the drive shaft 11 at the end portion of the drive shaft 11, as compared with the case where a flange of another component is connected to the drive shaft. Thus, the structure of the drive shaft 11 is simplified, and the axial length can be shortened. Further, the female screw member 15 and the drive shaft 1 are connected by the through bolt 16.
Since 1 is firmly integrated, the drive shaft 11 can better resist axial pulling as compared with the case where a snap ring is fitted to the drive shaft on the center side of the differential case to lock the conical gear. The rattling of the direction is also small.

Further, since the protector section A is secured by a slight modification of the conventional transmission case and drive shaft (a pair of cylindrical surfaces 11A, 12A), the axial dimension of the drive shaft 11 can be increased and the design can be improved. It is not necessary to reduce the degree of freedom of the above, add the total number of parts, or increase the weight. In addition, in the embodiment, the differential device incorporated in the automatic transmission for driving front wheels is described, but the present invention is also applicable to a differential device for driving rear wheels.

[0026]

According to the first aspect of the present invention, the inner cylindrical surface and the outer peripheral rotating surface are opposed to each other outside the sealing device so that the lip portion of the sealing device cannot be directly viewed from the outside. Water does not directly act on the sealing device, and there is no risk of damaging the lip of the sealing device or the sliding surface of the drive shaft. Further, since this protective structure can be formed by a slight design change of existing parts, there is no concern that the number of parts of the device will increase or the entire size will increase and the mountability on the vehicle will be impaired.

According to the second aspect of the present invention, the inner cylindrical surface and the outer peripheral rotating surface are axially overlapped with each other to form a pair of cylindrical surfaces. Does not interfere with shaft attachment / detachment or axial movement.

According to the invention of claim 3, since the drive shaft is assembled to the gear mechanism by the female screw member and the through bolt, the degree of freedom of assembly similar to that of the differential device shown in Japanese Utility Model Laid-Open No. 7-12650 is provided. Can be secured. Further, since the flange portion that connects the shaft on the driving wheel side can be configured integrally with the drive shaft, the number of parts can be reduced, and the overall size can be reduced. Settings etc. become easy.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a differential device incorporated in an automatic transmission.

FIG. 2 is an enlarged view of an oil seal mounting portion.

FIG. 3 is a partial enlarged view of a differential case.

[Explanation of symbols]

 10 Transmission Case 11 Drive Shaft 11A, 12A Cylindrical Surface 11S, 14S Spline 12 Converter Housing 13, 14 Conical Gear 15 Female Thread Member 15A Female Thread 15S Projection 16 Through Bolt 16A Male Thread 17 Differential Case 18 Shaft 19 Final Gear 21A Lip Part 21C, 21D Oil seal 22A, 22B Bearing device 23 Gear 24 Spring 24R Spring retainer 25 Cone ring A Protector structure

Claims (3)

[Claims] 1. A differential case that incorporates a pair of drive shafts that respectively transmit a driving force to the left and right driving wheels, and a gear mechanism that interlocks the pair of drive shafts, and holds the pair of drive shafts so that they can rotate relative to each other. A pair of bearing devices that are arranged at positions that sandwich the gear mechanism of the differential case in the axial direction and rotatably hold the entire differential case with respect to a housing; and the drive shaft that is attached to the housing. A rotatably sealing the differential case and a seal device for isolating the bearing device from the inside of the housing, wherein the inner cylinder encloses the drive shaft on the outer side in the axial direction of the seal device. The surface is provided on the housing and faces the inner cylinder surface with a narrow gap. Provided the outer peripheral surface of revolution overlapping in a direction to the drive shaft, differential gear, characterized in that the structure can not be direct at least a lip portion of the sealing device from the gap of the outer peripheral rotary surface and the inner cylindrical surface. 2. The inner cylindrical surface and the outer peripheral rotating surface are parallel cylindrical surfaces each having a diameter larger than a lip portion of the sealing device, and the drive shaft is axially arranged with respect to the housing. The differential device according to claim 1, wherein the differential device has a structure that does not interfere with the movement of the differential device. 3. The conical gear, wherein the gear mechanism forms a spline that meshes with a spline of the drive shaft, and urges the conical gear from the center of the differential case toward the conical gear toward the inner wall surface of the differential case. , A female screw member that limits the axial movement of the conical gear, and a through bolt that axially penetrates the drive shaft to fix the female screw member to the drive shaft, the spline of the conical gear, 3. The differential device according to claim 2, wherein a projection that meshes with the drive shaft in common is formed on the female screw member.