JP5251001B2 - Bush bearing and automotive rack and pinion type hydraulic power steering apparatus using the same - Google Patents

Description

  The present invention relates to a bush bearing, and more particularly to a bush bearing suitable for use in movably supporting a rack shaft in a rack and pinion type hydraulic power steering apparatus of an automobile.

Japanese Utility Model Publication 1-17-1775 Japanese Utility Model Publication No. 5-49566 Registered Utility Model No. 2576192 JP 11-115773 A JP 2001-10511 A

  As described in Patent Documents 1 to 5, in a rack and pinion type steering device, in particular, a rack and pinion type hydraulic power steering device, a rack shaft having rack teeth that mesh with the teeth of the pinion houses oil. It is movably supported at one end of the outer cylinder (housing) via a bush bearing. As a bush bearing, an inner cylinder made of metal or resin that is fitted to the inner peripheral surface of one end of the outer cylinder, and an outer peripheral surface of the rack shaft that is mounted on the inner peripheral surface of the inner cylinder and is the inner peripheral surface There have been proposed various types including a synthetic resin bush that is slidably in contact with the bush.

  In such a bush bearing, if there is a gap between the inner peripheral surface of the bush and the outer peripheral surface of the rack shaft, a collision sound between the bush and the rack shaft may be generated when the vehicle is running, which may cause discomfort to the passengers. If the rack shaft is tightly tightened with a large bushing with a bush so as not to cause a gap, the sliding frictional resistance in the axial direction increases, and the rack shaft cannot be supported with good movement characteristics, but is supported. If the rack shaft is tightened loosely with a small allowance, good axial movement characteristics with low sliding friction resistance against the rack shaft can be expected. A gap or the like is easily generated between them, and the radial rigid support is also lowered.

  For this reason, a technique has been proposed in which an elastic ring such as an O-ring is interposed between the outer peripheral surface of the bush and the inner peripheral surface of the inner cylinder so as to generate a gap and perform appropriate tightening. According to the technology, since a groove for fitting an elastic ring such as an O-ring is formed on the inner peripheral surface of the inner cylinder, it takes time for processing and causes an increase in price.

  On the other hand, the rack shaft is normally movably supported by the bush bearings at two portions, the side adjacent to the pinion and the side away from the pinion. In particular, the rack shaft is separated from the pinion in the rack and pinion type hydraulic power steering device. In addition to the movable support of the rack shaft by the bush bearing, the oil liquid from the inside of the outer cylinder to the outside is provided at one end of the opening side of the outer cylinder in which the oil liquid is accommodated. The leakage prevention is performed with a seal ring. However, if such a leakage prevention seal ring and bush bearing must be individually installed inside the outer cylinder, it becomes a complicated operation, which also increases the price. May be invited.

  The present invention has been made in view of the above-described points, and an object of the present invention is to obtain a good axial movement characteristic with a low sliding frictional resistance with respect to the rack shaft without causing a gap. Bush bearings that can support the rack shaft with an appropriate tightening allowance so that the number of processing steps and assembly steps can be reduced and the cost can be reduced, and the rack and pinion type hydraulic power steering device of an automobile using the same Is to provide.

  The bush bearing according to the present invention is fitted into the inner surface of the outer cylinder at one end of the outer cylinder through which the rack shaft is inserted, and penetrates through the inner cylinder through one end of the rack shaft inserted into the outer cylinder. Made of a synthetic resin that can be reduced in diameter, having an inner cylinder with a hole, and a bush through hole that is fitted to the inner cylinder inner surface of the inner cylinder and through which one end of the rack shaft is inserted into the outer cylinder. The inner cylinder is formed on the outer surface of the inner cylinder so as to receive the outer surface of the inner cylinder fitted to the inner surface of the outer cylinder and the seal ring that is elastically pressed into contact with the inner surface of the outer cylinder. An annular inner cylinder outer surface groove, an inner cylinder inner surface defining an inner cylinder through-hole, and an annular end portion of the outer cylinder connected to one end in the axial direction of the inner cylinder inner surface and connected to the outer cylinder inner surface One annular outer end surface that contacts the inner end surface of the step portion and the other connected to the other axial end of the inner surface of the inner cylinder The inner cylindrical inner surface has a cylindrical large-diameter inner peripheral surface connected to one annular outer end surface at one end in the axial direction, and a diameter of the large-diameter inner peripheral surface. One intermediate inner peripheral surface of a small diameter, an annular large-diameter stepped end surface connected to the other axial end of the large inner peripheral surface and one axial end of the intermediate inner peripheral surface, and one intermediate inner peripheral A cylindrical small-diameter inner peripheral surface having a smaller diameter than the surface diameter, and one annular small-diameter stepped end surface connected to the axial other end of the intermediate inner peripheral surface and one axial end of the small-diameter inner peripheral surface, respectively. The other intermediate inner peripheral surface of the cylinder having a diameter larger than the diameter of the small inner peripheral surface, the other axial end of the small inner peripheral surface, and one axial end of the other intermediate inner peripheral surface are connected to each other. The bush has an inner peripheral surface of a cylindrical bush that slidably contacts the outer peripheral surface of the rack shaft and a small inner peripheral surface of the inner cylinder. A cylindrical portion having a respective outer peripheral surface and a slit extending from one axial end surface to the other axial end surface, and projecting radially outward from the outer circumferential surface of one axial end portion of the cylindrical portion. And one flange portion contacting one annular small-diameter step end surface, and the other annular small-diameter step portion projecting radially outward from the outer peripheral surface of the other axial end portion of the cylindrical portion. The inner peripheral surface of the bush is integrally formed with a cylindrical surface extending in parallel with the outer peripheral surface of the rack shaft, and is connected to the cylindrical surface. And a bulging cylindrical surface that bulges radially inward at a portion that faces the portion in the radial direction.

  According to the bush bearing of the present invention, in the synthetic resin bush, the bush inner peripheral surface of the cylindrical portion is connected to the cylindrical surface extending in parallel with the outer peripheral surface of the rack shaft and connected to the cylindrical surface. And a bulging cylindrical surface that bulges radially inward at a portion that is radially opposed to the flange portion of the rack, so that the outer circumferential surface of the rack shaft and the bush of the cylindrical portion are formed by the bulging cylindrical surface. The rack shaft can be supported with an appropriate tightening margin so that a good movement characteristic in the axial direction can be obtained with a low sliding friction resistance with respect to the rack shaft. Moreover, it is not necessary to provide a groove for mounting an elastic ring such as an O-ring interposed between the outer peripheral surface of the bush and the inner peripheral surface of the inner cylinder on the inner peripheral surface of the inner cylinder. The inner surface of the inner cylinder is at one end in the axial direction. Cylindrical large-diameter inner peripheral surface connected to an annular outer end surface, an axial other end of the large-diameter inner peripheral surface, and an annular large-diameter stepped end surface connected to one axial end of the intermediate inner peripheral surface Therefore, one end of the outer cylinder of the bush bearing is fitted with a seal ring that prevents leakage of the oil from the inside of the outer cylinder to the outside in a hole defined by the large-diameter inner peripheral surface. As a result, the assembly man-hour can be reduced, and the cost can be reduced in combination with the reduction of the processing man-hour.

  The inner cylinder may be formed of a metal material such as aluminum or iron, or may be formed of a synthetic resin material instead.The synthetic resin as a bushing material has excellent wear resistance and low friction characteristics. In addition, those having predetermined flexibility and rigidity and less thermal expansion and contraction are preferable. Specifically, a synthetic resin containing at least one of polyacetal resin, polyamide resin, polyolefin resin, and fluororesin is used. Can be mentioned.

  In a preferred example, the inner cylinder extends in the axial direction from one end that opens at the outer end surface, and has a plurality of recesses that are arranged between the outer circumferential groove of the inner cylinder that is annular in the radial direction and the large-diameter inner peripheral surface. In this case, the plurality of recesses may be arranged at equiangular intervals in the direction around the axis, and in another preferred example, the inner cylindrical inner surface is the diameter of the other intermediate inner peripheral surface. Other large-diameter inner peripheral surfaces having a larger diameter than the other, an annular other end connected to the other axial end of the other intermediate inner peripheral surface and the other axial end of the other larger-diameter inner peripheral surface. The inner cylinder extends in the axial direction from one end opened at the other large-diameter step end face and is radially outer and the inner cylinder outer face and the other intermediate inner peripheral face. And a plurality of other recesses disposed between the inner peripheral surface of the small diameter, and the other plurality of recesses are equiangular in the direction around the axis When the bushing is fitted to the inner peripheral surface of one end portion of the outer cylinder, the dimensions of the inner peripheral surface of one end portion of the outer cylinder are arranged with a space and the inner cylinder has these recesses. Even if the accuracy is somewhat poor, this can be absorbed by the recess, so that the outer circumferential surface of the rack shaft is excessively pressed and biased by the bulging cylindrical surface or the cylindrical surface, or the bulging cylindrical surface and the outer circumferential surface of the rack shaft It is possible to prevent a gap from being generated.

  The slit may extend in parallel with the axial direction, or alternatively, may extend while being inclined with respect to the axial direction.The width of the slit is determined by inserting a bush from one end of the inner cylinder. The bush may be elastically reduced in diameter to such an extent that the bush can be fitted to the inner surface.

  A rack and pinion type hydraulic power steering device for an automobile according to the present invention is slidable between an outer cylinder through which a rack shaft is inserted into an oil-filled interior and one end portion of the rack shaft inserted into the outer cylinder. In order to support, the bush bearing according to any one of the above-described aspects is fitted to the inner surface of the outer cylinder at one end of the outer cylinder, the seal ring received in the inner cylinder outer surface groove of the inner cylinder, and the outer cylinder in the axial direction. It is arranged between the inner end surface of the annular step portion at one end and the end surface of the large-diameter step portion of the inner cylinder and contacts the large-diameter inner peripheral surface of the inner cylinder on the outer peripheral side, while on the outer peripheral surface of the rack shaft on the inner peripheral side And another seal ring that slidably contacts.

  As the seal ring received in the annular inner cylinder outer surface groove of the inner cylinder of the bush bearing, a generally used O-ring can be preferably used, and the other seal rings are circular, oval, rectangular or flat in cross section. May have other oval shapes such as an X-shaped cross-section, a U-shaped cross-section or a trapezoidal cross-section, and preferably made of natural rubber or synthetic Although it is made of rubber, it may be a thermoplastic synthetic resin having other elasticity, such as a polyester elastomer.

  According to the present invention, it is possible to support the rack shaft with an appropriate tightening margin so that good movement characteristics in the axial direction can be obtained with low sliding friction resistance with respect to the rack shaft without causing a gap. In addition, it is possible to provide a bush bearing that can reduce the number of processing steps and assembly steps and can reduce the price, and a rack and pinion type hydraulic power steering device for an automobile using the bush bearing.

  The invention will now be described in more detail with reference to the preferred embodiment examples shown in the drawings. The present invention is not limited to these examples.

  1 to 7, a rack and pinion type hydraulic power steering apparatus 1 for an automobile of this example includes an outer cylinder (housing) 4 in which a rack shaft 3 is inserted into an interior 2 filled with an oil liquid, and an outer cylinder 4 A bush fitted to the cylindrical inner peripheral surface 7 of the one end portion 6 of the outer cylinder 4 so as to slidably support the one end portion 5 of the rack shaft 3 inserted through the inside 2 in the A direction which is the axial direction. The bearing 8, the seal ring 11 received in the annular inner cylinder outer surface groove 10 of the inner cylinder 9 of the bush bearing 8, the annular step inner end surface 12 of the one end 6 of the outer cylinder 4 in the A direction, and the bush bearing 8 is arranged between the large-diameter stepped end surfaces 13 of the inner cylinder 9 and contacts the large-diameter inner peripheral surface 15 of the inner cylinder 9 of the bush bearing 8 on the outer periphery 14 side, while the rack shaft is on the inner peripheral surface 16 side. 3, another seal ring 18 slidably contacting the outer peripheral surface 17 in the A direction; One end portion 21 and a bellows-shaped elastic cover 22 for preventing anchored mud and dust penetration by tightening ring 20 to the inner cylinder outer surface 19 of the cylinder 9.

  A meshing mechanism with a pinion rotated by rotation of a steering wheel (steering wheel) on the other end side of the rack shaft 3, a mechanism for supplying oil to the inside 2 of the outer cylinder 4, and one end portion 5 of the rack shaft 3 Since a connecting mechanism with a tie rod or the like for transmitting the movement of the rack shaft 3 in the A direction on the side to the axle is well known, detailed description thereof will be omitted.

  One end portion 6 of the outer cylinder 4 having a long cylindrical outer cylinder main body 23 and a cylindrical collar 24 fitted to the inner peripheral surface 7 of the outer cylinder main body 23 is a cylindrical shape of the outer cylinder main body 23. Of the outer cylinder body 23 extending in a direction orthogonal to the A direction by connecting to the outer surface 25 at the outer peripheral end in the radial direction and the inner peripheral surface 7 at the inner peripheral end in the radial direction. An outer end surface 27 having an annular shape is formed, and a hole 28 for fitting the bush bearing 8 which is defined on the inner surface 26 of the outer tube and opened at the outer end surface 27 is formed at one end portion 6 of the outer tube 4. Has been.

  The outer cylinder inner surface 26 includes a cylindrical inner peripheral surface 7 extending in the A direction of the outer cylinder main body 23, a step portion inner end surface 12 extending in a direction orthogonal to the A direction of the outer cylinder main body 23, and the cylinder of the rack shaft 3. The outer peripheral surface 17 is opposed to the outer peripheral surface 17 with an annular gap 31 and has a small-diameter inner peripheral surface 32 of a collar 24 which is smaller in diameter than the inner peripheral surface 7 and extends in the A direction. The stepped inner end surface 12 is connected to the inner peripheral surface 7 at the outer peripheral end in the radial direction, and to the small inner peripheral surface 32 at the inner peripheral end in the radial direction. A location 33 is formed, and the interior 2 communicates with the hole 28 through a gap 31. The outer cylinder 4 may be a thick cylindrical body formed by integrally forming the outer cylinder main body 23 and the collar 24 instead of including the outer cylinder main body 23 and the collar 24. You may comprise the outer cylinder main body 23 and the elongate cylindrical body fitted by the inner peripheral surface 7 of the outer cylinder main body 23. FIG.

  The bush bearing 8 is fitted on the inner peripheral surface 7 of the outer cylinder inner surface 26 of the one end portion 6 of the outer cylinder 4 through which the rack shaft 3 is inserted, and is also inserted into the inner 2 of the outer cylinder 4. Of the inner cylinder 9 having an inner cylinder through-hole 40 through which one end 5 of the outer cylinder 3 passes, and the rack shaft 3 fitted into the inner cylinder inner surface 41 of the inner cylinder 9 and inserted into the inside 2 of the outer cylinder 4. A bush 43 made of a synthetic resin with a freely reducing diameter having a bush through hole 42 through which the one end portion 5 passes is provided.

  The inner cylinder 9 is fitted to the inner peripheral surface 7 of the outer cylinder inner surface 26 of the one end portion 6 of the outer cylinder 4 and is elastic to the inner cylinder outer surface 19 extending in the A direction and the inner peripheral surface 7 of the outer cylinder inner surface 26. An annular inner cylinder outer surface groove 10 formed in the outer surface 19 of the inner cylinder so as to receive the seal ring 11 that is pressed and contacted, and an inner cylinder through hole 40 through which the one end portion 5 of the rack shaft 3 passes are defined. An inner cylinder inner surface 41 extending in the A direction, and an outer cylinder 4 connected to one end in the A direction of the inner cylinder inner surface 41 at the inner peripheral end in the radial direction and connected to the inner peripheral surface 7 on the outer cylinder inner surface 26. One annular outer end 46 that contacts the annular inner end surface 12 of the annular end of the one end 6 and extends in the direction perpendicular to the A direction, and the other end in the A direction of the inner cylindrical inner surface 41 The other annular outer end surface 47 connected at the peripheral end and extending in the direction orthogonal to the A direction; 6 extends from the one end opened in the A direction and is arranged between the annular inner cylindrical outer surface groove 10 and the large inner diameter surface 15 of the inner cylindrical inner surface 41 in the radial direction, and around the axis. A plurality of recesses 48 arranged at equiangular intervals in the R direction, and the inner cylinder 9 extending in the A direction from one end opened at the large-diameter stepped end surface 49 of the inner cylinder inner surface 41 and in the radial direction. The inner cylinder outer surface 19 and the inner cylinder inner surface 41 are arranged between the intermediate inner peripheral surface 50 and the small-diameter inner peripheral surface 51, and are arranged at equiangular intervals in the R direction, which is the direction around the axis. And a plurality of recesses 52.

  The inner cylinder inner surface 41 of the inner cylinder 9 is connected to an annular outer end surface 46 at one end in the A direction and has a cylindrical large diameter inner peripheral surface 15 extending in the A direction, and a large diameter inner peripheral surface 15. A cylindrical intermediate inner peripheral surface 55 having a smaller diameter than the diameter and extending in the A direction; the other end in the A direction of the large inner peripheral surface 15; and one end in the A direction of the intermediate inner peripheral surface 55 An annular large-diameter stepped end surface 13 that is connected at the end and the inner peripheral end and extends in a direction perpendicular to the A direction, and a cylindrical shape that is smaller in diameter than the intermediate inner peripheral surface 55 and extends in the A direction. Are connected to the other end in the A direction of the intermediate inner peripheral surface 55 and one end in the A direction of the small inner peripheral surface 51 at the outer peripheral end and the inner peripheral end in the radial direction, respectively, and are orthogonal to the A direction. An annular small-diameter stepped end surface 56 extending in the direction, a cylindrical intermediate inner peripheral surface 50 that is larger than the diameter of the small-diameter inner peripheral surface 51 and extends in the A direction, and a small diameter An annular small-diameter stepped portion extending in a direction perpendicular to the A direction, connected to the other end in the A direction of the peripheral surface 51 and one end in the A direction of the intermediate inner peripheral surface 50 at the inner peripheral end and the outer peripheral end in the radial direction. An end surface 57, a cylindrical large-diameter inner peripheral surface 58 that is larger than the diameter of the intermediate inner peripheral surface 50 and extends in the A direction, the other end in the A direction of the intermediate inner peripheral surface 50, and a large-diameter inner periphery An annular large-diameter stepped end surface 49 is provided at one end in the A direction of the surface 58 and extends in a direction orthogonal to the A direction, connected to the inner peripheral end and the outer peripheral end in the radial direction.

  The inner cylinder outer surface 19 of the inner cylinder 9 has a small-diameter cylindrical shape in which an inner cylinder outer surface groove 10 is formed and extends in the A direction in addition to the annular outer end surfaces 46 and 47 extending in a direction orthogonal to the A direction. The outer peripheral surface 65, a cylindrical outer peripheral surface 66 that is larger than the diameter of the outer peripheral surface 65 and extends in the A direction, the other end of the outer peripheral surface 65 in the A direction, and one end of the outer peripheral surface 66 in the A direction. And an annular step end surface 67 which is connected to the outer peripheral end and the inner peripheral end in the direction and extends in a direction perpendicular to the A direction. An annular protrusion 68 projecting outward in the direction is integrally formed, and an annular groove 69 and a circle deeper than the groove 69 are connected to the groove 69 in the A direction on the outer peripheral surface 66. An annular groove 70 is formed.

  The inner cylinder 9 has an outer end surface 46 in contact with the stepped inner end surface 12, an outer peripheral surface 65 in contact with the inner peripheral surface 7, and a stepped end surface 67 in contact with the outer end surface 27, and a projection 68 is fitted in the recess 33. The seal ring 11 made of an O-ring that is fitted to the inner peripheral surface 7 of the one end 6 of the outer cylinder 4 and received in the inner cylinder outer surface groove 10 is elastically pressed against the inner peripheral surface 7. The telescopic cover 22 has one end 21 fitted in the grooves 69 and 70 and is fixed to the outer surface 19 of the inner cylinder 9 by the fastening ring 20 at the one end 21.

  The bush 43 slidably contacts the outer peripheral surface 17 of the rack shaft 3 and contacts the cylindrical bush inner peripheral surface 75 extending in the A direction and the small diameter inner peripheral surface 51 of the inner cylinder 9 and extends in the A direction. A cylindrical portion 80 having a cylindrical bush outer peripheral surface 76 and a slit 79 extending from one end surface 77 in the A direction to the other end surface 78 in the A direction, and one end portion 81 in the A direction of the cylindrical portion 80. The outer peripheral surface 76 of the other end portion 83 in the A direction of the cylindrical portion 80 and the one flange portion 82 that protrudes radially outward from the bush outer peripheral surface 76 and contacts the annular small-diameter stepped end surface 56. And the other flange portion 84 that protrudes radially outward and contacts the annular small-diameter stepped end surface 57.

  The cylindrical outer peripheral surface 90 of the flange 82 that contacts the intermediate inner peripheral surface 55 and extends in the A direction is between the pair of semi-annular outer peripheral surfaces 91 and 92 and the semi-annular outer peripheral surfaces 91 and 92 in the R direction. The intermediate inner peripheral surface 55 has a shape complementary to the cylindrical outer peripheral surface 90 of the flange portion 82, and is a pair of semi-annular outer peripheral surfaces 91 and 92. A pair of semi-annular inner peripheral surfaces 94 and 95 which are in contact with each other, and a flat surface 96 which is disposed between the semi-annular inner peripheral surfaces 94 and 95 in the R direction and which contacts the flat surface 93. Thus, the bush 43 cannot be rotated in the R direction with respect to the inner cylinder 9.

  The inner peripheral surface 75 of the bush swells radially inward at a cylindrical surface 98 extending parallel to the outer peripheral surface 17 of the rack shaft 3 and connected to the cylindrical surface 98 and opposed to the flange 82 in the radial direction. And a protruding bulging cylindrical surface 99.

  The bush 43 loosely tightens the outer peripheral surface 17 of the rack shaft 3 with a small tightening allowance at the cylindrical surface 98 and relatively tightens the outer peripheral surface 17 of the rack shaft 3 with a relatively large tightening allowance at the bulging cylindrical surface 99.

  In the rack and pinion hydraulic power steering device 1 having the bush bearing 8 described above, the cylindrical inner surface 75 of the cylindrical portion 80 has a cylindrical inner surface 75 extending in parallel with the outer peripheral surface 17 of the rack shaft 3 in the A direction. And the bulging cylindrical surface 99 connected to the cylindrical surface 98, the bulging cylindrical surface 99 causes the outer peripheral surface 17 of the rack shaft 3 and the bush inner peripheral surface 75 of the cylindrical portion 80 to It is possible to support the rack shaft 3 with an appropriate tightening margin so that no gap is generated between the rack shaft 3 and good movement characteristics in the A direction can be obtained with a low sliding friction resistance with respect to the rack shaft 3. In addition, it is necessary to provide the inner cylinder inner surface 41 of the inner cylinder 9 with a groove for mounting an elastic ring such as an O-ring interposed between the bush outer peripheral surface 76 of the bush 43 and the inner cylinder inner surface 41 of the inner cylinder 9. Results, no processing man-hours In addition, the inner cylinder inner surface 41 of the inner cylinder 9 is connected to the annular outer end face 46 at one end in the A direction in the A direction of the cylindrical large diameter inner peripheral surface 15 and the large diameter inner peripheral surface 15. Leakage of oil from the inside 2 of the outer cylinder 4 to the outside because it has an annular large-diameter stepped end surface 13 connected to the other end and one end in the A direction of the intermediate inner peripheral surface 55, respectively. The seal ring 18 can be fitted in the hole defined by the large-diameter inner peripheral surface 15 in advance to reduce the assembly man-hours. sell.

  In the rack and pinion hydraulic power steering device 1, the annular end surface 102 in the A direction of the bush 43 including the annular end surface 101 in the A direction of the one end surface 77 and the flange 82 is the A direction of the seal ring 18. Since the cylindrical end portion 80 of the bulging cylindrical surface 99 is prevented from passing through the bulging cylindrical surface 99, the bulging cylindrical surface 99 can be prevented from passing over. The effect can be maintained.

It is sectional explanatory drawing of an example of preferable embodiment of this invention. It is an expanded sectional explanatory view of the bush bearing and seal ring of the example shown in FIG. It is a left view of the bush bearing shown in FIG. It is a right view of the bush bearing shown in FIG. It is an expanded sectional explanatory view of the bush of the example shown in FIG. It is a left view of the bush shown in FIG. FIG. 6 is an enlarged explanatory view of a part of the bush shown in FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rack and pinion type hydraulic power steering apparatus 2 Inside 3 Rack shaft 4 Outer cylinder 5, 6 One end part 7 Inner peripheral surface 8 Bush bearing 9 Inner cylinder 10 Inner cylinder outer surface groove 11 Seal ring 12 Step part inner end surface 13 Large diameter step part end surface 14 Outer periphery 15 Large diameter inner peripheral surface 16 Inner peripheral surface 17 Outer peripheral surface 18 Seal ring 40 Inner cylinder through-hole 41 Inner cylinder inner surface 42 Bushing through-hole 43 Bush

Claims (4)

An inner cylinder fitted with an inner surface of an outer cylinder at one end of an outer cylinder through which the rack shaft is inserted and having an inner cylinder through-hole through which one end of the rack shaft is inserted into the outer cylinder; A bush made of a synthetic resin that can be reduced in diameter and has a bush through-hole that is fitted into the inner cylinder inner surface of the inner cylinder and through which one end of the rack shaft is inserted into the outer cylinder. The inner cylinder has an inner cylinder outer surface fitted to the inner surface of the outer cylinder, and an annular inner cylinder outer surface groove formed on the outer surface of the inner cylinder so as to receive a seal ring that elastically presses and contacts the inner surface of the outer cylinder. The inner cylinder inner surface defining the inner cylinder through-hole, and the inner end surface of the annular cylinder at one end of the outer cylinder connected to the axial inner end of the inner cylinder inner surface and the outer cylinder inner surface. One annular outer end surface and the other annular outer end surface connected to the other axial end of the inner cylinder inner surface The inner cylindrical inner surface has a cylindrical large-diameter inner peripheral surface connected to one annular outer end surface at one end in the axial direction, and one intermediate inner peripheral surface smaller in diameter than the large-diameter inner peripheral surface. An annular large-diameter stepped end surface connected to the other axial end of the large-diameter inner peripheral surface and one axial inner end of the intermediate inner peripheral surface, and a diameter smaller than the diameter of one intermediate inner peripheral surface A cylindrical small-diameter inner peripheral surface, one annular small-diameter stepped end surface connected to the other axial end of one intermediate inner peripheral surface and one axial end of the small-diameter inner peripheral surface, and a small-diameter inner peripheral surface The other cylindrical small inner diameter connected to the other cylindrical inner peripheral surface having a larger diameter than the other diameter, the other axial end of the small inner peripheral surface, and one axial end of the other intermediate inner peripheral surface. The bush has an inner peripheral surface of a cylindrical bush that is slidably in contact with the outer peripheral surface of the rack shaft, and an outer peripheral surface of the bush that is in contact with a small inner diameter surface of the inner cylinder. One from one end face in the axial direction and a cylindrical portion having a elongated slit to the other end surface in the axial direction, with protruding from the outer peripheral surface of one axial end of the cylindrical portion radially outward with a respective The outer peripheral surface that contacts the intermediate inner peripheral surface of the ring, and one flange portion that contacts the end surface of one annular small-diameter stepped portion, and the outer peripheral surface of the other end portion in the axial direction of the cylindrical portion radially outward And the other flange portion that protrudes and contacts the other annular small-diameter stepped end surface, and the bush inner peripheral surface has a cylindrical surface that extends parallel to the outer peripheral surface of the rack shaft, and A bush bearing having a bulging cylindrical surface that is connected to the cylindrical surface and that bulges radially inward at a portion facing one flange portion in the radial direction.   The inner cylinder extends in the axial direction from one end opening at the outer end surface and has a plurality of recesses arranged between the outer ring groove on the inner cylinder in the radial direction and the large-diameter inner peripheral surface, The bush bearing according to claim 1, wherein the plurality of recesses are arranged at equiangular intervals in a direction around the axis.   The inner cylinder inner surface is composed of another cylindrical large inner peripheral surface having a diameter larger than the diameter of the other intermediate inner peripheral surface, the other axial end of the other intermediate inner peripheral surface, and another large inner peripheral surface. And an annular other large-diameter stepped end surface connected to one end in the axial direction of the inner tube, and the inner cylinder extends in the axial direction from one end opened at the other large-diameter stepped end surface. It has a plurality of other recesses arranged between the outer surface of the inner cylinder in the radial direction and the other intermediate inner peripheral surface and the small-diameter inner peripheral surface, and the other plurality of recesses are directions around the axis. The bush bearing according to claim 1, wherein the bush bearings are arranged at equiangular intervals.   An outer cylinder through which the rack shaft is inserted into the oil-filled interior and one end of the rack shaft inserted into the outer cylinder are slidably supported on the inner surface of the outer cylinder at one end of the outer cylinder. The bush bearing according to any one of claims 1 to 3, the seal ring received in the inner cylinder outer surface groove of the inner cylinder, and an annular step inner end face of one end of the outer cylinder in the axial direction In addition to being arranged between the large-diameter stepped end surfaces of the inner cylinder and contacting the large-diameter inner peripheral surface of the inner cylinder on the outer peripheral side, the inner peripheral side is slidably in contact with the outer peripheral surface of the rack shaft. An automotive rack and pinion type hydraulic power steering apparatus having a seal ring.

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