JP3945977B2 - Rack and pinion type hydraulic power steering system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a so-called drop-in structure rack and pinion type hydraulic power steering apparatus.
[0002]
[Prior art]
A rack-and-pinion hydraulic power steering apparatus 100 having a drop-in structure shown in FIG. 4 covers a pinion 102 integrally formed on the outer periphery of an output shaft 101 rotated by steering with a pinion housing 103 and is separated from the pinion 102 in the axial direction. A hydraulic control valve 104 provided around the output shaft 101 at a position is covered by a valve housing 105, and a steering assist force is generated by a hydraulic actuator (not shown) that operates according to the hydraulic pressure controlled by the hydraulic control valve 104. The outer periphery on one end side of the valve housing 105 is fitted to the inner periphery on one end side of the pinion housing 103 via an O-ring 113. In the pinion housing 103, the output shaft 101 is supported by a rolling bearing 106 between the pinion 102 and the hydraulic control valve 104, and supported by a bearing 107 on the side farther from the hydraulic control valve 104 than the pinion 102. The inner ring 106 a of the rolling bearing 106 is fixed to the output shaft 101 by being sandwiched between an inner ring receiving portion 110 formed on the outer periphery of the output shaft 101 and a retaining ring 111 fitted to the output shaft 101. In the pinion housing 103, a receiving portion 108 for receiving the pinion side end surface of the outer ring 106b of the rolling bearing 106 is provided. The outer ring 106 b is fixed to both the housings 103 and 105 by being sandwiched between the receiving portion 108 and the end surface 105 a of the valve housing 105. An oil seal 112 that seals between the outer periphery of the output shaft 101 and the inner periphery of the valve housing 105 is disposed between the hydraulic control valve 104 and the rolling bearing 106. Further, the O-ring 113 is disposed between the inner periphery on one end side of the pinion housing 103 and the outer periphery on the one end side of the valve housing 105, so that water enters the housings 103 and 105 from between the connecting portions of both. Is prevented.
[0003]
In the above structure, the hydraulic control valve 104 and the output shaft 101 are assembled into the valve housing 105 to form an assembly, and then the valve housing 105 is inserted after the drop-in process of inserting the output shaft 101 in the assembly into the pinion housing 103. Since the assembly is completed simply by connecting the pinion housing 103 and the pinion housing 103, the assembly is simplified.
[0004]
[Problems to be solved by the invention]
However, due to processing tolerances and assembly tolerances, the distance between the receiving portion 108 and the end surface 105a of the valve housing 105 is larger than the axial dimension of the outer ring 106b of the rolling bearing 106. Therefore, there is a problem that the output shaft 101 rattles in the axial direction with respect to the housings 103 and 105. Therefore, although a shim corresponding to the gap is interposed between the receiving portion 108 and the outer ring 106b, there is a problem that the number of parts and assembly man-hours increase.
[0005]
In addition, the need for a waterproof member such as an O-ring 113 to prevent water from entering the housings 103 and 105 also increases the number of parts and the number of assembly steps.
[0006]
An object of the present invention is to provide a rack and pinion type hydraulic power steering apparatus that can solve the above-described problems.
[0007]
[Means for Solving the Problems]
The present invention includes an output shaft that rotates by steering, a pinion that is integrally formed on the outer periphery of the output shaft, a rack that meshes with the pinion, a pinion housing that covers the pinion, and an axial direction away from the pinion In the position, the present invention is applied to a rack and pinion type hydraulic power steering apparatus including a hydraulic control valve provided around the output shaft and a valve housing that covers the hydraulic control valve and is coupled to the pinion housing.
According to the present invention, a rolling bearing that supports the output shaft is provided between the pinion and the hydraulic control valve, an inner ring of the rolling bearing is fixed to the output shaft, and an outer ring of the rolling bearing is mounted on the pinion housing. A pinion-side receiving portion for receiving the pinion-side end surface is provided, and an end surface of the valve housing has a valve-side receiving portion for receiving the valve-side end surface of the outer ring, between the outer periphery of the output shaft and the inner periphery of the valve housing. An oil seal is disposed between the hydraulic control valve and the rolling bearing, and the oil seal has an annular metal core covered with a sealing material, and the output shaft is radially outward from the metal core. An intermediate portion that is integrally formed with the core metal, and the intermediate portion is disposed between the valve-side receiving portion and the valve-side end surface of the outer ring. An outer portion disposed between the end surface of the valve housing and the end surface of the pinion housing on the outer side in the radial direction of the output shaft with respect to the valve side end surface of the outer ring, and the outer portion of the interposition portion and the pinion An annular elastic member disposed between the end face of the housing is bonded to the outer part of the interposition part, and the outer ring and the inner part of the interposition part are connected to each other by the connection between the pinion housing and the valve housing. An elastic member sandwiched between the side receiving portion and the valve side receiving portion and sandwiched between both housings together with the outer portion of the interposition portion is compressed in the output shaft axial direction.
According to the configuration of the present invention, the inner ring of the rolling bearing that supports the output shaft is fixed to the output shaft, and the outer ring and the inner part of the interposition part together with the pinion side receiving part provided in the pinion housing and the valve side provided in the valve housing Since it is pinched | interposed with a receiving part, the shakiness of the axial direction of the output shaft with respect to both housings can be prevented.
Since the elastic member sandwiched between the two housings together with the outer portion of the interposition portion is compressed in the axial direction of the output shaft, the two housings can be connected to each other without rattling, and water can enter the two housings by the elastic member. Can be prevented. That is, the elastic member serves both as a shim for preventing the output shaft from rattling with respect to both housings of the rolling bearing and a water stop member for preventing water from entering the two housings.
Further, the elastic member is bonded to the interposition part, and the interposition part is integrally formed with an oil seal metal core that seals between the outer periphery of the output shaft and the inner periphery of the valve housing. The elastic member can be incorporated at the same time, and the number of assembly steps can be reduced.
[0008]
The end surface of the pinion housing is arranged closer to the pinion side than the valve side end surface of the outer ring, and the thickness of the elastic member in the output shaft axial direction in the natural state is the end surface of the pinion housing and the valve side end surface of the outer ring. It is preferable to be larger than the output shaft axial distance between the two.
As a result, the outer ring can be reliably sandwiched between the receiving portions and the elastic member can be compressed.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A rack and pinion hydraulic power steering apparatus 1 shown in FIG. 1 includes an input shaft 2 connected to a steering wheel (not shown), and an output shaft 4 connected to the input shaft 2 via a torsion bar 3. Yes. The torsion bar 3 is connected to the input shaft 2 via a pin 5 and connected to the output shaft 4 via a serration 6. Thereby, the input shaft 2 and the output shaft 4 are elastically rotated relative to each other according to the steering torque. A pinion 7 is integrally formed on the outer periphery of the output shaft 4 so as to rotate together, and a rack 8 that meshes with the pinion 7 is connected to a wheel (not shown). The rotation of the input shaft 2 due to the steering is transmitted through the torsion bar 3, so that the output shaft 4 rotates together with the pinion 7, and the rack 8 moves in the vehicle width direction. As the rack 8 moves, the steering angle of the wheels changes. A support yoke 16 that supports the rack 8 is pressed against the rack 8 by the elasticity of the spring 17.
[0010]
A hydraulic cylinder 12 is provided as a hydraulic actuator for generating steering assist force. The hydraulic cylinder 12 includes a cylinder tube configured by a pinion housing 21 that covers the pinion 7 and the rack 8, a piston 13 that is formed integrally with the rack 8, and a pair of oil chambers 14 that are partitioned by the piston 13, 15.
[0011]
A rotary hydraulic control valve 11 is provided around the output shaft 4 at a position away from the pinion 7 in the axial direction. The hydraulic control valve 11 is covered with a valve housing 22 connected to the pinion housing 21 and is connected to the output shaft 4 so as to rotate along with the output shaft 4, and the first valve member 24 and a second valve member 25 provided integrally on the outer periphery of the input shaft 2. The first valve member 24 rotates relative to the valve housing 22 about the axis of the output shaft 4 by the rotation of the output shaft 4. The two valve members 24 and 25 are relatively rotated by elastic relative rotation of the input / output shafts 2 and 4 according to the steering torque. Between the valve members 24 and 25 is an inter-valve oil passage 27. In the inter-valve oil passage 27, the oil chambers 14 and 15 of the pump P and the hydraulic cylinder 12 are ports 22 a and 22 c provided in the valve housing 22. 22e and oil passages 24a, 24b, 24c formed in the first valve member 24, and a port 22d in which a tank T is provided in the valve housing 22 in the inter-valve oil passage 27, The oil passages 2 a and 2 b formed in the input shaft 2 and the input shaft 2 and the torsion bar 3 are connected to each other. The ports 22a, 22c, 22d, and 22e are sealed by a seal ring 26 that is disposed between the outer peripheral surface of the first valve member 24 and the inner peripheral surface of the valve housing 22. In the inter-valve oil passage 27, a throttle whose opening changes in accordance with the relative rotation amount of both valve members 24 and 25 can control the hydraulic pressure of the pressure oil discharged from the pump P in accordance with the relative rotation amount. Is provided. The pressure oil is supplied to one of the oil chambers 14 and 15 of the hydraulic cylinder 12 according to the steering direction, and returns to the tank T via the hydraulic control valve 11 from the other. As a result, the hydraulic cylinder 12 is operated according to the hydraulic pressure controlled by the hydraulic control valve 11, thereby generating a steering assist force that acts on the rack 8. A known valve can be used as the hydraulic control valve 11.
[0012]
The input shaft 2 is supported by a ball bearing 31 provided in the valve housing 22 and a bush 32 fitted in a recess formed at the end of the output shaft 4. The hydraulic control valve 11 is disposed between the bearing 31 and the bush 32. An oil seal 33 that seals between the outer periphery of the input shaft 2 and the inner periphery of the valve housing 22 is provided on the anti-pinion side of the hydraulic control valve 11.
[0013]
The output shaft 4 is supported by a ball bearing (rolling bearing) 41 provided in the valve housing 22 between the pinion 7 and the hydraulic control valve 11, and on the side farther from the hydraulic control valve 11 than the pinion 7. It is supported by a needle bearing 49.
[0014]
As shown in FIGS. 2 and 3, the inner ring 41 a of the ball bearing 41 includes an inner ring receiving portion 42 formed by a step formed on the outer periphery of the output shaft 4, and a retaining ring fitted on the outer periphery of the output shaft 4. It is fixed to the output shaft 4 by being sandwiched by 43.
[0015]
A step formed on the inner periphery of the pinion housing 21 constitutes a pinion-side receiving portion 44 that receives the pinion-side end surface of the outer ring 41 b of the ball bearing 41. The inner side of the end surface 22a of the valve housing 22 is a valve-side receiving portion 45 that receives the valve-side end surface of the outer ring 41b.
[0016]
An oil seal 51 that seals between the outer periphery of the output shaft 4 and the inner periphery of the valve housing 22 is disposed between the hydraulic control valve 11 and the ball bearing 41. The oil seal 51 of the present embodiment is positioned by being disposed between the step 22 ′ formed on the inner periphery of the valve housing 22 and the ball bearing 41. The oil seal 51 has a configuration in which a metal core 51a is covered with a rubber seal material 51b, and a lip portion 51b 'that is in contact with the outer periphery of the output shaft 4 is provided on the inner peripheral side of the seal material 51b.
[0017]
A plate-shaped annular interposition part 52 extending from the metal core 51a of the oil seal 51 to the outside in the radial direction of the output shaft 4 is integrally formed with the metal core 51a. The interposition part 52 has an inner part 52a and an outer part 52b. The inward portion 52a is disposed between the valve side receiving portion 45 and the valve side end surface of the outer ring 41b. The outer portion 52b is disposed between the end surface 22a of the valve housing 22 and the end surface 21a of the pinion housing 21 on the outer side in the radial direction of the output shaft than the valve side end surface of the outer ring 41b. The outer peripheral surface of the outer portion 52 b of the interposition part 52 is set along a cylindrical surface concentric with the inner peripheral surface of the oil seal 51 in contact with the outer periphery of the output shaft 4.
[0018]
An annular elastic member 53 disposed between the outer part 52 b of the interposition part 52 and the end surface 21 a of the pinion housing 21 is bonded to the outer part 52 b of the interposition part 52. The elastic member 53 is made of the same rubber as the sealing material 51b in this embodiment. The end surface 21a of the pinion housing 21 is arranged on the pinion side only as indicated by t1 in FIG. 3 from the valve side end surface of the outer ring 41b. The thickness of the elastic member 53 in the output shaft axial direction in the natural state is indicated by t2 in FIG. 2, and the thickness t2 is the output shaft axis between the end surface of the pinion housing 21 and the valve side end surface of the outer ring 41b. It is made larger than the direction distance t1. For example, t1 = 0.3 mm and t2 = 0.5 mm.
[0019]
The pinion housing 21 and the valve housing 22 have flanges 21b and 22b projecting outward, and a bolt 55 inserted into one flange 22b is screwed into a female screw formed on the other flange 21b. The housings 21 and 22 are connected. Due to the connection between the pinion housing 21 and the valve housing 22, the outer ring 41 b and the inner part 52 a of the interposition part 52 are sandwiched between the pinion side receiving part 44 and the valve side receiving part 45, and The elastic member 53 sandwiched between the housings 21 and 22 together with the outer portion 52b is compressed in the output shaft axial direction. For example, when t1 = 0.3 mm and t2 = 0.5 mm, the elastic member 53 is reliably compressed by 0.2 mm. The end faces 21b 'and 22b' of both flanges 21b and 22b are separated from each other by an output shaft axial distance t1 between the end face 21a of the pinion housing 21 and the valve side end face of the outer ring 41b. Thereby, by fastening both the flanges 21b and 22b with the bolt 55, both the flanges 21b and 22b are elastically bent toward the respective end surfaces. Thereby, the elasticity for preventing loosening of the bolt 55 can be imparted.
[0020]
The end surface 22 b ′ of the flange 22 b of the valve housing 22 has a pinion as much as the thickness of the interposition portion 52 formed by the core metal 51 a of the oil seal 51 rather than the end surface 22 a of the valve housing 22 that forms the valve side receiving portion 45. Located on the side. Thereby, a peripheral wall surface 61 extending from the end face of the valve housing 22 toward the pinion side is formed so as to surround the interposition part 52.
[0021]
According to the above configuration, after the hydraulic control valve 11 and the output shaft 4 are assembled into the valve housing 22 to form an assembly, the valve housing is formed after the drop-in process of inserting the output shaft 4 in the assembly into the pinion housing 21. 22 and the pinion housing 21 are connected by a bolt 55. The inner ring 41 a of the ball bearing 41 that supports the output shaft 4 is fixed to the output shaft 4, and the outer ring 41 b is provided in the pinion side receiving part 44 provided in the pinion housing 21 and the valve housing 22 together with the inner part 52 a of the interposition part 52. Since it is sandwiched between the valve-side receiving portion 45 to be driven, it is possible to prevent the output shaft 4 from rattling in the axial direction with respect to both the housings 21 and 22. The elastic member 53 bonded to the outer part 52b of the interposition part 52 is compressed in the output shaft axial direction by being sandwiched between the housings 21 and 22 together with the outer part 52b of the interposition part 52. 21 and 22 can be connected without rattling, and the elastic member 53 can prevent water from entering the housings 21 and 22. That is, the elastic member 53 includes a shim for preventing the output shaft 4 from rattling with respect to both the housings 21 and 22 of the ball bearing 41, and a water stop member for preventing water from entering the both housings 21 and 22. Combined use. Further, the interposition part 52 to which the elastic member 53 is bonded is integrally formed with a core metal 51a of an oil seal 51 that seals between the outer periphery of the output shaft 4 and the inner periphery of the valve housing 22. The oil seal 51 and the elastic member 53 can be assembled at the same time, and the number of assembly steps can be reduced.
[0022]
The present invention is not limited to the above embodiment. For example, the support of the output shaft between the pinion and the hydraulic control valve is not limited to the ball bearing, and may be a rolling bearing.
[0023]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the rack and pinion type hydraulic power steering apparatus which can reduce the number of parts for the prevention of rattling of the output shaft with respect to a housing and waterproofing, and an assembly man-hour can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a steering device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view before assembling a main part of a steering device according to an embodiment of the present invention. Sectional view after assembling the part [Fig. 4] Cross-sectional view of a conventional steering device [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rack and pinion type hydraulic power steering device 4 Output shaft 7 Pinion 8 Rack 11 Hydraulic control valve 12 Hydraulic cylinder 21 Pinion housing 22 Valve housing 24 First valve member 41 Ball bearing 41a Inner ring 41b Outer ring 44 Pinion side receiving part 45 Valve side receiving part 51 oil seal 51a metal core 51b seal material 52 interposition part 52a inner part 52b outer part 53 elastic member

Claims (2)

An output shaft that rotates by steering;
A pinion integrally formed on the outer periphery of the output shaft;
A rack meshing with the pinion,
A pinion housing that covers the pinion;
A hydraulic control valve provided around the output shaft at a position axially away from the pinion;
In a rack and pinion type hydraulic power steering apparatus that covers the hydraulic control valve and includes a valve housing connected to the pinion housing,
Between the pinion and the hydraulic control valve, a rolling bearing that supports the output shaft is provided,
The inner ring of the rolling bearing is fixed to the output shaft,
The pinion housing is provided with a pinion side receiving portion for receiving the pinion side end surface of the outer ring of the rolling bearing,
The end surface of the valve housing has a valve side receiving portion that receives the valve side end surface of the outer ring,
An oil seal that seals between the outer periphery of the output shaft and the inner periphery of the valve housing is disposed between the hydraulic control valve and the rolling bearing,
The oil seal has an annular core covered with a sealing material,
An interposition part extending from the cored bar outward in the radial direction of the output shaft is integrally formed with the cored bar,
The interposition part includes an inner part disposed between the valve side receiving part and the valve side end face of the outer ring, and an end face of the valve housing and a pinion on the outer side in the output shaft radial direction than the valve side end face of the outer ring. An outer portion disposed between the end surface of the housing and
An annular elastic member disposed between the outer part of the interposition part and the end surface of the pinion housing is bonded to the outer part of the interposition part,
Due to the connection between the pinion housing and the valve housing, the outer ring and the inner part of the interposition part are sandwiched between the pinion side receiving part and the valve side receiving part, and are sandwiched by both housings together with the outer part of the interposition part. A rack and pinion type hydraulic power steering device, wherein the elastic member is compressed in the axial direction of the output shaft. The end surface of the pinion housing is arranged on the pinion side with respect to the valve side end surface of the outer ring,
2. The rack according to claim 1, wherein the thickness of the elastic member in the output shaft axial direction in the natural state is larger than the distance in the output shaft axial direction between the end surface of the pinion housing and the valve side end surface of the outer ring. Pinion type hydraulic power steering device.

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