JP2010247609A - Rack-and-pinion type steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent generation of noise by surely regulating oscillation of a pinion shaft in a rack and pinion type steering device. <P>SOLUTION: A resin elastic body 16 fixed to a lower end 71 of the pinion shaft 7 includes a semi-spherical body 15 as a projecting part projecting downward from the lower end 71 of the pinion shaft 7. A spherical surface part 15a forming a part of a spherical surface is provided on a surface of the body 15. The spherical surface part 15a is received by a receiving recessed part 17 of a conical surface shape provided in the pinion housing 12. A contact region 19 of the spherical surface part 15a and the receiving recessed part 17 is arranged on a lower side of the lower end 71 of the pinion shaft 7. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rack and pinion type steering apparatus.

In this type of rack and pinion type steering device, the upper part of the pinion shaft is supported by a ball bearing, and the lower part of the pinion shaft is supported by a needle roller bearing.
The ball bearing has a predetermined axial gap. In addition, there is a predetermined radial gap between the pinion shaft and the needle roller bearing. For this reason, the pinion shaft is oscillated and displaced with the upper side ball bearing as a fulcrum while performing the grinding motion by the radial gap of the needle roller bearing.

  On the other hand, it has been proposed that a spherical portion protruding from the bottom of the housing is fitted into a concave portion formed on the lower end surface of the pinion shaft, and the concave portion is received by the spherical portion (see, for example, Patent Document 1).

JP 2000-128001 A

However, since the contact region between the concave portion and the spherical portion formed on the lower end surface of the pinion shaft is disposed above the lower end surface of the pinion shaft, the contact region from the ball bearing serving as the fulcrum of the swing of the pinion shaft The distance to is shortened. For this reason, when the pinion shaft receives a high swing input, the pinion shaft may be swung and displaced.
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a rack and pinion type steering device that can reliably restrain the occurrence of noise by reliably regulating the swing of the pinion shaft.

  In order to achieve the above object, the present invention provides a rack for supporting the upper part (7b) and the lower part (7c) of the pinion shaft (7) by a pair of rolling bearings (13, 14) supported by the housing (12). In the pinion type steering device (1), a convex part (15) projecting downward from the lower end (71) of the pinion shaft, and a spherical part (15a) provided on the surface of the convex part and forming a part of a spherical surface A conical concave receiving portion (17) that is provided in the housing and receives the spherical portion, and a contact area (19) between the spherical portion and the receiving concave portion is disposed below the lower end of the pinion shaft. It is characterized by.

  In the present invention, since the contact area between the spherical surface portion and the receiving recess is disposed below the lower end of the pinion shaft, the span between the rolling bearing on the upper side of the pair of rolling bearings and the contact area can be increased. it can. Therefore, the receiving recess contacting the spherical surface portion can provide a centering effect that reliably regulates the swing of the pinion shaft, and can reliably suppress the generation of noise due to the swing displacement. Further, there is no response delay due to the rocking displacement of the pinion shaft at the start of steering, and the steering feeling can be improved.

  The resin elastic body (16) may be fixed to the lower end of the pinion shaft and elastically compressed in the axial direction (Y1) of the pinion shaft, and the resin elastic body may include the convex portion. 2). In this case, the pinion shaft can be elastically biased upward in the axial direction, and the axial gap of the upper rolling bearing (for example, a ball bearing) can be removed. By regulating the swing angle of the rolling bearing as the fulcrum, the swing displacement of the pinion shaft can be more reliably regulated.

  The resin elastic body includes a press-fit portion (18) elastically press-fitted into a holding hole (73) formed in a lower end surface (72) of the pinion shaft, and a hemisphere as the convex portion having the spherical portion. And a main body (15) having a shape (claim 3). In this case, since it can be handled as a subassembly in which a resin elastic body is attached to the lower end of the pinion shaft, it is sufficient to assemble the subassembly into the pinion housing when assembling the rack and pinion type steering device. It becomes easy.

  The main body of the resin elastic body includes a pressure receiving surface (15b) facing the lower end surface of the pinion shaft, and a metal elastic body is interposed between the pressure receiving surface and the lower end surface of the pinion shaft. There is a case (Claim 4). In this case, since the resin elastic body and the metal elastic body are arranged in series, the spring constant of the both elastic bodies as a whole can be reduced. Accordingly, since a hard resin elastic body can be used as much as possible, it is possible to prevent the resin elastic body from sagging due to a change in the years. As a result, the urging force for urging the pinion shaft in the axial direction can be maintained over a long period of time, and the noise suppression effect can be maintained over a long period of time.

  In the above description, the alphanumeric characters in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

1 is a schematic diagram showing a schematic configuration of a rack and pinion steering device according to an embodiment of the present invention. It is sectional drawing of the principal part of a rack and pinion type steering device. It is the expanded sectional view which expanded a part of FIG. It is an expanded sectional view of the principal part of the rack and pinion type steering device of another embodiment of the present invention.

A preferred embodiment of the present invention will be described with reference to the accompanying drawings.
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
Referring to FIG. 1, a rack and pinion type steering device 1 includes a steering shaft 3 connected to a steering member 2 such as a steering wheel, an intermediate shaft 5 connected to the steering shaft 3 via a universal joint 4, A pinion shaft 7 connected to the intermediate shaft 5 via a universal joint 6 and a rack 8a meshing with a pinion 7a provided in the vicinity of the end of the pinion shaft 7 as a steered shaft extending in the left-right direction of the automobile And a rack shaft 8. The pinion shaft 7 and the rack shaft 8 constitute a rack and pinion mechanism A as a steering mechanism.

  The rack shaft 8 is supported in a rack housing 9 fixed to the vehicle body through a plurality of bearings (not shown) so as to be linearly reciprocable along the axial direction Z1. Both end portions of the rack shaft 8 protrude to both sides of the rack housing 9, and tie rods 10 are coupled to the respective end portions. Each tie rod 10 is connected to a corresponding steered wheel 11 via a corresponding knuckle arm (not shown).

When the steering member 2 is operated and the steering shaft 3 is rotated, this rotation is converted into a linear motion of the rack shaft 8 along the left-right direction of the automobile by the pinion 7a and the rack 8a. Thereby, the turning of the steered wheel 11 is achieved.
With reference to FIG. 2, the pinion 7 a of the pinion shaft 7 and the rack 8 a of the rack shaft 8 are meshed with each other in the pinion housing 12. The pinion shaft 7 has an upper portion 7b and a lower portion 7c sandwiching the pinion 7a with respect to the axial direction Y1 of the pinion shaft 7. The upper part 7b of the pinion shaft 7 is rotatably supported by a ball bearing 13 as a rolling bearing. The lower part 7c of the pinion shaft 7 is rotatably supported by a needle roller bearing 14 as a rolling bearing.

A resin elastic body 16 including a hemispherical main body 15 is attached to the lower end 71 of the pinion shaft 7, and the main body 15 constitutes a convex portion protruding downward from the lower end 71 of the pinion shaft 7. The main body 15 is received by a receiving recess 17 provided in the pinion housing 12.
As shown in FIG. 3, the resin elastic body 16 includes a shaft-like press-fit portion 18 that is elastically press-fitted into a holding hole 73 formed in a lower end surface 72 of the pinion shaft 7, and the main body 15 that forms a convex portion. And have. The shape of the press-fit portion 18 in the free state may be a columnar shape, or may be provided with a diameter-enlarged portion in the middle or at the end to make the press-fit of the press-fit portion 18 stronger.

  The surface of the convex portion constituted by the hemispherical body 15 constitutes a spherical portion 15a that forms a part of a spherical surface. Further, the pinion housing 12 is formed with a conical receiving recess 17 for receiving the spherical portion 15a. A contact area 19 between the spherical portion 15 a and the conical receiving recess 17 is disposed below the lower end surface 72 of the pinion shaft 7. The contact region 19 has an annular shape centered on the axis of the pinion shaft 7.

  Referring to FIG. 2 again, the rack and pinion type steering device 1 is equipped with a rack shaft support device 20. The rack shaft support device 20 includes a housing 22 having a holding hole 21 formed of a circular hole, and is accommodated in the holding hole 21 so as to be slidable along the depth direction X1 of the holding hole 21 and the rear surface of the rack 8a of the rack shaft 8. And a support yoke 23 as a rack shaft support member that slidably supports 8b.

The rack shaft support device 20 is interposed between a sealing screw 24 as a sealing member that is screwed and fixed to the inlet of the holding hole 21, and between the support yoke 23 and the sealing screw 24, and the support yoke 23. And a biasing member 25 that biases the rack toward the rack shaft 8 side. The biasing member 25 is made of a compression coil spring, for example.
The housing 22 is formed integrally with the pinion housing 12 and is disposed on the opposite side of the pinion shaft 7 with the rack shaft 8 therebetween. The pinion housing 12 and the housing 22 are manufactured by die casting, for example.

A female screw portion 21b is formed on the inner peripheral surface 21a at the entrance of the holding hole 21, and the sealing screw 24 is screwed and fixed to the female screw portion 21b.
The support yoke 23 as the rack shaft support member is formed on the front surface 23 a facing the rack shaft 8, the rear surface 23 b facing the sealing screw 24, and the rear surface 23 b, and accommodates the urging member 25. It has a recess 23c and an outer peripheral surface 23d made of a cylindrical surface.

  On the front surface 23 a of the support yoke 23, a concave surface 26 that substantially matches the shape of the back surface 8 b of the rack shaft 8 is formed. A sliding contact plate 27 is attached along the concave surface 26, and the sliding contact plate 27 is in sliding contact with the back surface 8 b of the rack shaft 8. As the sliding contact plate 27, a plate having a low friction coefficient is preferably used. For example, a metal plate or a metal plate coated with a fluororesin can be used.

  A pair of receiving grooves 28 extending in the circumferential direction and having an annular shape are formed on the outer peripheral surface 23 d of the support yoke 23, and each receiving groove 28 accommodates an annular elastic member 29 made of, for example, an O-ring. . On the outer peripheral surface of the sealing screw 24, an annular accommodating groove 30 extending in the circumferential direction is formed, and an annular elastic member 31 made of, for example, an O-ring is accommodated in the accommodating groove 30.

  According to the present embodiment, the contact area 19 between the spherical portion 15a of the main body 15 of the resin elastic body 16 and the receiving recess 17 is disposed below the lower end 71 of the pinion shaft 7, so that the upper ball bearing 13 and The span between the contact area 19 can be increased. Therefore, a centering effect that reliably restricts the swinging of the pinion shaft 7 can be achieved by the receiving recess 17 in contact with the spherical surface portion 15a.

  As a result, for example, even if an impact load is applied to the pinion shaft 7, it is possible to reliably suppress the generation of noise due to the swinging displacement of the pinion shaft 7. In addition, there is no response delay due to the rocking displacement of the pinion shaft 7 at the start of steering, and the steering feeling can be improved. In order to further suppress noise and improve steering feeling, a lubricant such as grease may be applied to the contact region 19.

  Further, since the resin elastic body 16 fixed to the lower end 71 of the pinion shaft 7 includes the main body 15 as the convex portion and is elastically compressed in the axial direction Y1 of the pinion shaft 7, the pinion shaft 7 is It can be elastically biased upward in the axial direction Y1, and the axial gap of the upper ball bearing 13 can be removed. As a result, the rocking displacement of the pinion shaft 7 can be more reliably regulated by regulating the rocking angle of the upper ball bearing 13 as a pivot point of the pinion shaft 7.

  Further, since the resin elastic body 16 includes the press-fit portion 18 that is elastically press-fitted into the holding hole 73 of the lower end surface 72 of the pinion shaft 7 and the hemispherical main body 15 as the convex portion, the pinion shaft 7 It can be handled as a subassembly having a resin elastic body 16 attached to the lower end. Therefore, when the rack-and-pinion type steering apparatus 1 is assembled, the sub-assembly may be incorporated into the pinion housing 12, and as a result, the assembly is facilitated.

The resin used for the resin elastic body 16 is a polyacetal resin, a polyamide resin, or a phenol resin having a low coefficient of friction for reducing the frictional resistance between the resin elastic body 16 and the receiving recess 17 of the pinion housing 12 made of, for example, an aluminum alloy. Alternatively, it is preferable to use a peak resin.
Further, the contact angle θ of the spherical portion 15a with respect to the receiving recess 17 (corresponding to the angle formed by the normal line in the contact region 19 and the central axis C1 of the pinion shaft 7) is set in a range of 8 ° ≦ θ ≦ 38. Is preferred. When the contact angle θ is less than 8 °, the centering effect is reduced. On the contrary, when the contact angle θ exceeds 38 °, the distance between the contact region 19 and the central axis C1 becomes long, so that when the resin elastic body 16 rotates with respect to the receiving recess 17 (that is, the pinion shaft 7). The friction torque (especially the rotation starting torque when starting to rotate) increases.

Therefore, by setting the contact angle θ to an angle range of 8 ° ≦ θ ≦ 38, the friction torque of the pinion shaft 7 is reduced and a sufficient centering effect can be obtained.
Next, FIG. 4 shows another embodiment of the present invention. Referring to FIG. 4, the present embodiment is different from the embodiment of FIG. 3 between the pressure receiving surface 15 b of the main body 15 of the resin elastic body 16 and the recess provided in the lower end surface 72 of the pinion shaft 7. The metal elastic body 32 is interposed. It is not necessary to provide a recess in the lower end surface 72. As the metal elastic body 32, for example, a single or a plurality of stacked disc springs may be used, or a compression coil spring may be used. When a disc spring is used as the metal elastic body 32, there is almost no increase in space, which can contribute to downsizing.

  In the present embodiment, the same operational effects as the embodiment of FIG. 3 can be obtained. Furthermore, since the resin elastic body 16 and the metal elastic body 32 are arranged in series, the spring constant of both the elastic bodies 16 and 32 as a whole can be reduced. Therefore, since the hard thing can be used as the resin elastic body 16 as much as possible, it is possible to prevent the resin elastic body 16 from sag due to a change in the diameter of the resin elastic body 16. As a result, the urging force that urges the pinion shaft 7 in the axial direction Y1 can be maintained over a long period of time, and the noise suppression effect can be maintained over a long period of time.

  In addition, various modifications can be made within the scope of the claims of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Rack and pinion steering device, 7 ... Pinion shaft, 7a ... Pinion, 7b ... Upper part, 7c ... Lower part, 8 ... Rack shaft, 12 ... Pinion housing, 13 ... Ball bearing (rolling bearing), 14 ... Needle roller bearing ( Rolling bearing), 15 ... main body (convex part), 15a ... spherical part, 15b ... pressure receiving surface, 16 ... resin elastic body, 17 ... receiving concave part, 18 ... press-fitting part, 19 ... contact region, 32 ... metal elastic body, 71 ... Lower end, 72 ... Lower end face, 73 ... Holding hole

Claims (4)

In the rack and pinion type steering device that supports the upper and lower portions of the pinion shaft by a pair of rolling bearings supported by the housing,
A convex portion projecting downward from the lower end of the pinion shaft;
A spherical portion provided on the surface of the convex portion and forming a part of a spherical surface;
A conical receiving recess provided in the housing and receiving the spherical portion,
A rack and pinion type steering device, wherein a contact area between the spherical portion and the receiving recess is disposed below the lower end of the pinion shaft. The resin elastic body according to claim 1, comprising a resin elastic body fixed to the lower end of the pinion shaft and elastically compressed in the axial direction of the pinion shaft,
The rack-and-pinion type steering device, wherein the resin elastic body includes the convex portion.   The resin elastic body according to claim 2, wherein the resin elastic body includes a press-fit portion elastically press-fitted into a holding hole formed in a lower end surface of the pinion shaft, and a hemispherical main body as the convex portion having the spherical portion. A rack and pinion type steering device comprising:   4. The resin elastic body according to claim 3, wherein the main body of the resin elastic body includes a pressure receiving surface facing a lower end surface of the pinion shaft, and a metal elastic body is interposed between the pressure receiving surface and the lower end surface of the pinion shaft. A rack and pinion type steering device.

Images