JP2012214192A - Vehicle steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a vehicle rack and pinion type steering device.SOLUTION: A vehicle steering device 10 which transmits a steering torque from a steering wheel to steered wheels 21 and 21 via a rack-and-pinion mechanism 15 includes: a rack shaft 16 in which a rack 32 is formed; two rack support parts 50 and 50 positioned to both sides of a longitudinal direction of the rack shaft relative to the position of a pinion 31; and an urging part 60 positioned between the two rack support parts. The two rack support parts are positioned close to each other to support only a back surface 16a of the region where the rack is formed in the rack shaft which is positioned in a steering neutral position, the back surface being supported to be able to slide in the longitudinal direction. The urging direction of the urging part is set so that the rack shaft can be energized at least a direction other than towards the rack.

Description

  The present invention relates to an improved technique of a rack and pinion type steering device mounted on a vehicle.

  The rack and pinion type steering device transmits a steering torque generated by steering a steering wheel from a steering wheel to a steering wheel via a rack and pinion mechanism. The rack and pinion mechanism converts the rotational movement of the steering wheel into a linear movement. Various techniques are known as such a rack and pinion type steering device (for example, refer to Patent Document 1).

  The rack and pinion type steering device known from Patent Document 1 includes three rack support portions for slidably supporting a rack shaft on which a rack of a rack and pinion mechanism is formed. The three rack support portions support the rack shaft so as to be slidable in the axial longitudinal direction. The rack shaft is supported by a rack guide so that the back surface of the portion where the rack is formed is slidable in the longitudinal direction of the shaft.

  However, the length of the rack shaft known in Patent Document 1 needs to be at least twice the range in which the rack moves in the linear direction. For this reason, the rack and pinion mechanism must be large in the longitudinal direction of the rack. Since the housing for storing the rack and pinion mechanism is also increased in size, it is disadvantageous in reducing the size and weight of the steering device. In particular, when such a steering device is mounted on a small vehicle having a small vehicle width, there are great restrictions on arrangement, and there are also restrictions on the length of tie rods connected to both ends of the rack shaft. There is room for further improvement in order to increase the degree of freedom in vehicle design.

JP 2006-088978 A

  It is an object of the present invention to provide a technique capable of reducing the size of a rack and pinion type steering device.

In the invention according to claim 1, in the vehicle steering device that transmits the steering torque generated by steering the steering wheel to the steering wheel from the steering wheel via the rack and pinion mechanism,
A rack shaft on which a rack of the rack and pinion mechanism is formed, two rack support portions located on both sides in the longitudinal direction of the rack shaft with respect to the position of the pinion of the rack and pinion mechanism, An urging portion located between the rack support portions,
The two rack support parts are configured to support only the back surface of the rack shaft in a state where the rack shaft is positioned at a neutral position of steering so as to be slidable in the longitudinal direction of the shaft. Located close to each other,
The urging direction of the urging portion is set so as to be able to urge the rack shaft in at least a direction other than the rack.

  In the invention according to claim 2, the urging portion includes a rack guide that slidably supports the back surface of a portion of the rack shaft where the rack is formed in a longitudinal direction of the rack, and the rack guide is supported on the back surface. And the rack guide has a pressing surface for pressing the back surface, and the pressing surface is orthogonal to the center line of the rack shaft in the back surface. And it is formed so that it can contact only any one surface with respect to the pinion orthogonal reference line orthogonal to the centerline of the said pinion.

  In the invention according to claim 3, at least the back surface of the rack shaft is formed in a substantially arc-shaped cross section, the pressing surface is formed in a substantially arc-shaped cross section along the back surface, and the arc-shaped radius of the pressing surface. Is set to be larger than the arcuate radius of the back surface, and the center of the pressing surface is offset in the tooth width direction of the rack with respect to the center line of the rack shaft.

  In the invention according to claim 4, the urging portion includes a rack guide that supports the back surface of the rack shaft at a portion where the rack is formed so as to be slidable in a longitudinal direction of the rack, and the rack guide is supported on the back surface. And a center line of the rack guide and a center line of the compression coil spring are orthogonal to the center line of the rack shaft and orthogonal to the center line of the pinion. Inclined in the axial direction of the pinion with respect to a reference line.

  In the invention according to claim 5, the two rack support portions are constituted by cylindrical bearings, and the center line of the rack shaft is offset in a direction away from the pinion with respect to the center line of the bearing. And it is offset along the centerline of the pinion.

  In the invention according to claim 6, a straight line perpendicular to the center line of the rack shaft and parallel to the center line of the pinion is used as a pinion parallel reference line, and the two rack support portions are configured by cylindrical bearings. The two rack-opposite convex portions that can be supported by the two bearings are formed on the same circumference of the outer peripheral surface of the rack shaft, and the two rack-opposite convex portions are It is located on the opposite side of the rack with respect to the pinion parallel reference line and on both sides of the pinion orthogonal reference line.

  In the invention according to claim 7, two rack approaching side convex portions that can be supported by the two bearings are formed on the same circumference of the outer peripheral surface of the rack shaft. The approaching convex portions are located between the pinion parallel reference line and the rack, and are located on both sides of the pinion orthogonal reference line.

  In the invention according to claim 8, the rack shaft is made of a hollow material, and the two rack opposite side convex portions and the two rack approaching side convex portions are radially outward from the inside of the hollow material. It is the part formed by extruding toward.

  The invention according to claim 9 is characterized by further comprising a swing restricting portion for restricting the rack guide from swinging around the pinion orthogonal reference line.

  In the invention according to claim 10, the rack guide is a circular member centered on the pinion orthogonal reference line, and is housed in a rack guide housing, and the rack guide housing includes the rack guide that is orthogonal to the pinion. A circular support hole that can be slidably supported along a reference line, and the swing restricting portion is formed in a circumferential direction of the outer peripheral surface of the rack guide, It is comprised by the at least 2 convex part which can contact a surrounding surface, It is characterized by the above-mentioned.

  In the invention according to claim 11, the rack guide is a circular member centered on the pinion orthogonal reference line, and is housed in a rack guide housing, and the rack guide housing includes the rack guide that is orthogonal to the pinion. A circular support hole that can be slidably supported along a reference line, and the swing restricting portion is provided between an outer peripheral surface of the rack guide and an inner peripheral surface of the support hole. It is characterized by being comprised by the filling layer which has viscoelasticity, such as a liquid packing, with which the clearance gap was filled.

  In the invention according to claim 12, the rack guide is a circular member centered on the pinion orthogonal reference line, and an annular groove for mounting an O-ring is formed on the outer peripheral surface. The rack guide housing has a circular support hole capable of slidably supporting the rack guide along the pinion orthogonal reference line, and the swing restricting portion is It is comprised by the O-ring with which the annular groove was mounted | worn, The outer peripheral surface of this O-ring is contacting the inner peripheral surface of the said support hole over the perimeter.

  The invention according to claim 13 is characterized in that the center of the annular groove is offset with respect to the center line of the rack guide.

  In the invention which concerns on Claim 14, the said urging | biasing part urges | biases the said pinion in the direction which meshes with the said rack, It is characterized by the above-mentioned.

  According to a fifteenth aspect of the present invention, the rack is a straight tooth whose tooth traces are perpendicular to the rack axis.

  In the invention according to claim 1, the two rack support portions can support only the back surface of the portion where the rack is formed on the rack shaft, and are positioned close to each other. There is no rack on the back. The urging portion positioned between the two rack support portions can urge the rack shaft at least in a direction other than the rack. In other words, the urging portion can press the rack shaft toward the pinion and can further press the back surface of the rack shaft against each rack support portion (add a preload). A reaction force corresponding to the preload is generated in each rack support portion. Each rack support portion supports the back surface of the rack shaft. This rack shaft support configuration corresponds to a so-called “support configuration under a balancing condition in which a beam projects from both sides of two fulcrums and a concentrated load (reaction force of pinion) acts on the longitudinal center of the beam”. In this way, the back surface of the rack shaft is reliably supported by the three points of the pinion and the two rack support portions so as to be slidable in the longitudinal direction of the shaft. In addition, the rack itself is not supported by each rack support portion (not in contact). There is no need to provide a separate support member for supporting the rack shaft, and the support structure for supporting the rack shaft can be simplified.

  Furthermore, since the two rack support portions can support only the rear surface of the portion where the rack is formed on the rack shaft, they can be positioned close to each other. Since each rack support part can be located within the range of the length of the rack, the total length of the rack shaft can be shortened compared to the conventional case where the rack support part is located outside the range. For this reason, the rack and pinion mechanism can be reduced in size in the longitudinal direction of the rack. Since the rack shaft is shortened, the tie rods connected to both ends of the rack shaft are lengthened. However, the diameter of the tie rod is smaller than the diameter of the rack shaft. For this reason, the total weight of the weight of the rack shaft plus the weight of the tie rod is reduced. Further, the housing for housing the rack and pinion mechanism can be reduced in size as the rack shaft can be shortened. As described above, the steering device can be reduced in size and weight, and the cost can be reduced.

  Furthermore, the tie rod connected to the rack shaft can be lengthened as much as the rack shaft is shorter than the conventional one. For this reason, the freedom degree of design of a steering device and the vehicle carrying this steering device can be raised. For example, the degree of freedom in designing the suspension geometry formed by the tie rod of the steering device and the suspension device can be increased. In particular, when such a steering device is mounted on a small vehicle having a small vehicle width, there are few restrictions on arrangement. In addition, if the tie rod is lengthened, the influence of the toe change can be suppressed when the left and right steering wheels bump or rebound. As a result, the controllability of the vehicle can be improved.

  In general, when a long tie rod is used, the axial longitudinal force acting on the rack shaft (thrust force) particularly in a steering region where the steering angle is large, such as when steering a stopped vehicle (so-called stationary steering). It is easy to set to steering geometry, which can reduce the axial force). That is, the steering geometry can reduce the thrust acting on the rack shaft in a steering region where the steering angle is large. By reducing the thrust, the steering torque for steering the steering wheel is reduced. Since the steering torque is small, the burden on the rack and pinion mechanism is reduced. Accordingly, since the strength and durability of the rack and pinion mechanism can be afforded, the reliability of the rack and pinion mechanism is enhanced.

  In addition, when a so-called electric power steering device is adopted in which the auxiliary torque generated by the electric motor according to the steering torque is added to the rack and pinion mechanism, the steering torque is reduced. The auxiliary torque generated by the electric motor can be reduced correspondingly. Therefore, the electric motor can be reduced in size. For this reason, the weight of the entire steering apparatus can be reduced, and the power consumption of the steering apparatus can be reduced. Accordingly, the burden on the engine is reduced, and the fuel efficiency of the vehicle equipped with the steering device is increased.

  In the invention which concerns on Claim 2, an urging | biasing part is comprised by the rack guide and the compression coil spring. The pressing surface of the rack guide is formed so as not to contact the entire back surface of the rack shaft but to contact only one side with respect to the pinion orthogonal reference line. With such an extremely simple pressing surface, the rack shaft can be pressed toward the pinion, and the back surface of the rack shaft can be pressed against each rack support portion. It is not necessary to provide a separate component for pressing the back surface of the rack shaft against each rack support.

  In addition, only one half of the pressing surface of the rack guide is in contact with the back surface of the rack shaft, and the other half corresponding to the conventional rack guide is in contact with the rack support portion. That is, only the frictional resistance of one conventional rack guide acts. The conventional steering device is subjected to a frictional resistance that is the sum of the frictional resistance of the rack guide and the frictional resistance of the rack support portion that supports the rack shaft in the longitudinal direction. On the other hand, since only the frictional resistance corresponding to one rack guide acts on the steering device of the second aspect, the frictional resistance when the rack shaft slides can be suppressed.

  In the invention according to claim 3, the arcuate radius of the pressing surface of the rack guide is set larger than the arcuate radius of the back surface of the rack shaft. The center of the pressing surface is offset in the rack tooth width direction with respect to the center line of the rack shaft. With such an extremely simple pressing surface, the rack shaft can be pressed toward the pinion, and the back surface of the rack shaft can be pressed against each rack support portion. In addition, it is not necessary to provide a separate support member for supporting the rack shaft.

  In the invention according to claim 4, the center line of the rack guide is inclined in the axial direction of the pinion with respect to the pinion orthogonal reference line. With such a rack guide having an extremely simple configuration, the rack shaft can be pressed toward the pinion, and the back surface of the rack shaft can be pressed against each rack support portion. In addition, it is not necessary to provide a separate support member for supporting the rack shaft.

  In the invention which concerns on Claim 5, the two rack support parts are comprised by the cylindrical bearing. The center line of the rack shaft is offset in the direction away from the pinion with respect to the center line of the bearing and is offset along the center line of the pinion. For this reason, it can prevent more reliably that the rack itself is supported (contacted) by the two bearings.

  In the invention according to claim 6, the rack shaft has two convex portions on the opposite side of the rack that can be supported by cylindrical bearings on the same circumference of the outer circumferential surface except for the portion having the rack. Is formed. The two rack opposite convex portions are located on the opposite side of the rack from the pinion parallel reference line and on both sides of the pinion orthogonal reference line. Further, the center line of the rack guide is inclined in the axial direction of the pinion with respect to the pinion orthogonal reference line. For this reason, each bearing does not support the entire back surface of the rack shaft, but can support at least one of the two convex portions on the opposite side of the rack.

  In general, when steering during traveling, a relatively small steering force is required because the frictional force between the road surface and the steering wheel is small. When the steering force transmitted from the pinion to the rack is small, the pressing force pressing the back surface of the rack shaft against each bearing side is small. In this case, the rack opposite-side convex portion located on the opposite side of the rack guide with respect to the pinion orthogonal reference line is supported by each bearing. Of the rack shaft, the support point supported by each bearing is determined reliably.

  As the steering force transmitted from the pinion to the rack increases, the pressing force that presses the back surface of the rack shaft against each bearing side also increases. In this case, both of the two rack-opposite convex portions located on both sides with respect to the pinion orthogonal reference line are supported by each bearing. For this reason, since excessive steering force does not act on one point of each bearing, durability of a rack shaft and a bearing increases.

  In the invention which concerns on Claim 7, the two rack approaching side convex parts are formed on the same periphery of the outer peripheral surface of a rack shaft. The two rack approaching side convex portions are located between the pinion orthogonal reference line and the rack, and are located on both sides of the pinion orthogonal reference line.

  When steering a stopped vehicle, so-called stationary steering, the frictional force between the road surface and the steering wheel is large. In other words, since the road surface reaction force is increased, a larger steering force is required. Greater steering force is transmitted from the pinion to the rack. The rack shaft support configuration is a configuration in which the rack shaft projects from both sides of the two bearings, and a concentrated load (pinion pressing force) acts on the longitudinal center of the rack shaft. A larger pressing force acts on the longitudinal center of the rack shaft from the pinion, so that both sides of the rack shaft tend to bend toward the rack side. For this reason, the rack formed on the rack shaft tends to contact each bearing. However, in this case, since at least one of the two rack approaching side convex portions comes into contact with each bearing first, the rack does not come into contact with each bearing. Therefore, the rack shaft can slide more smoothly.

  In the invention according to claim 8, the two rack opposite convex portions and the two rack approaching convex portions are formed by extrusion from the inside of the rack shaft made of a hollow material toward the radially outward direction. Has been. For this reason, each surface of a rack opposite side convex part and a rack approaching side convex part becomes smoother (surface roughness becomes favorable). Accordingly, it is possible to suppress the frictional resistance of each convex portion with respect to each bearing when the rack shaft slides.

  In addition, the hardness of the rack opposite side convex part and the rack approaching side convex part is increased by work hardening by cold forging. As a result, it is possible to effectively increase the hardness of only the rack opposite side convex portion and the rack approaching side convex portion that are in contact with each bearing, that is, only the sliding portion. As a result, the rack opposite convex portion and the rack approaching convex portion can reduce wear due to sliding.

  In the invention according to claim 9, it is possible to restrict the swing of the rack guide around the pinion orthogonal reference line by the swing restricting portion. For this reason, the contact state of the pressing surface of the rack guide with respect to the back surface of the rack shaft can be maintained satisfactorily. In addition, this makes it possible to ensure a good meshing state between the pinion and the rack, thereby improving the strength and durability of the pinion and the rack. Furthermore, since the meshing state of the pinion and the rack is good, the frictional resistance due to the meshing can be reduced. As a result, the steering feeling of the steering device can be enhanced.

  In the invention which concerns on Claim 10, the rocking | fluctuation control part is comprised by the at least 2 convex part formed in the circumferential direction of the outer peripheral surface of a rack guide. For this reason, a rocking | fluctuation control part can be made into a very simple structure.

  In the invention according to claim 11, the swing restricting portion is constituted by a packed layer having a viscoelasticity such as a liquid packing, which is filled in a gap between the outer peripheral surface of the rack guide and the inner peripheral surface of the support hole. ing. For this reason, a rocking | fluctuation control part can be made into a very simple structure.

  In the invention according to claim 12, the swing restricting portion has a configuration in which an O-ring is mounted in an annular groove formed in the outer peripheral surface of the rack guide. The swing restricting portion can be configured with an extremely simple configuration in which an O-ring is simply mounted in an annular groove formed on the outer peripheral surface of the rack guide.

  In the invention according to claim 13, the center of the annular groove is offset with respect to the center line of the rack guide. When the rack guide is fitted into the support hole, the contact pressure of the O-ring with the inner surface of the support hole varies depending on the portion of the outer peripheral surface of the O-ring. That is, the contact pressure differs in the circumferential direction of the O-ring. Since the contact pressure varies depending on the portion of the outer peripheral surface of the O-ring, it is possible to further restrict the rack guide from swinging about the pinion orthogonal reference line.

  In the invention which concerns on Claim 14, the urging | biasing part is urging | biasing the direction which mesh | engages a pinion with a rack. For this reason, the rack is pressed against the pinion. The back surface of the rack shaft is reliably supported by the three points of the pinion and the two rack support portions so as to be slidable in the longitudinal direction of the shaft. Moreover, the rack itself is not supported by each rack support portion. For this reason, it is not necessary to provide a separate support member for supporting the rack shaft, and the support configuration can be simplified.

  In the invention according to claim 15, the rack is a “quick tooth”. For the pinion that meshes with this rack, it is set as “immediate teeth”. Alternatively, by making the pinion “a tooth” and tilting the pinion shaft by an angle corresponding to the torsion angle of the “a tooth”, the pinion can be substantially an “immediate tooth”. And can be configured. As described above, the meshing configuration of the pinion and the rack is substantially the same configuration as the case where both the pinion and the rack are “quick teeth”. For this reason, the direction of the teeth of the pinion coincides with the direction of the teeth of the rack.

  Therefore, when an external force (including vibration) in the direction of the tooth trace of the rack is applied to the rack, the rack is easily displaced in the direction of the “tooth trace”. For example, when vibration in the direction of the tooth trace of the rack is transmitted from the outside to the rack, the rack can vibrate in the direction of the tooth trace. For this reason, the vibration in the rack direction of the rack is converted into the vibration in the rotation direction of the pinion and is not easily transmitted to the steering wheel. As a result, the steering feeling given to the driver is enhanced. Also, the rack of “immediate teeth” acts to regulate the vibration in the rotation direction of the pinion. For this reason, vibration in the rotational direction of the pinion is difficult to be transmitted to the steering wheel. As a result, the steering feeling given to the driver is enhanced.

  Further, when the rack is a “helical tooth”, the tooth is formed obliquely with respect to the center line of the rack shaft. For this reason, in any cross section orthogonal to the center line of the rack shaft, there are rack teeth in part. On the other hand, according to the fifteenth aspect, since the rack is “immediately toothed”, when the rack is sectioned one after another along the center line of the rack axis, the tooth tip portion and the tooth bottom portion are repeated. In other words, depending on the cross section, there is a part having only the tooth bottom. The cross-sectional secondary moment of the part having only the tooth bottom is smaller than the cross-sectional secondary moment of the other part. Therefore, if the entire rack shaft is captured, it is relatively easy to bend as compared with the case where the rack is a “helical tooth”. Moreover, as described above, when an external force (including vibration) in the direction of the tooth trace of the rack is applied to the rack, the rack is easily displaced in the direction of the “tooth trace”. Therefore, the back surface of the rack shaft is reliably supported by the three points of the pinion and the two rack support portions so as to be slidable in the shaft longitudinal direction.

  Furthermore, since the rack is “quickly toothed”, when the rack shaft is subjected to a large road reaction force, such as during stationary steering, the rack shaft is displaced in the direction of the “tooth line” (tooth width direction) of the rack. Easy to do. For this reason, the rack shaft can rise along the surface of the support hole of each rack support portion in accordance with the road surface reaction force. That is, an indefinite support structure is formed in which the support position for supporting the rack shaft by the rack support portion changes according to the magnitude of the reaction force applied to the rack shaft. Therefore, the rack shaft can be sufficiently supported at the three points of the meshing point between the pinion and the rack and the support point by each rack support portion, and the reaction force can be received sufficiently and reliably. In addition, each rack support portion supports the rack shaft at the most appropriate portion corresponding to the magnitude of the reaction force, and therefore has high durability.

  Further, since the entire length of the rack shaft is short as described above, the pinion can be positioned at the center of the vehicle width. On the other hand, the steering wheel is biased to the left or right. That is, the pinion shaft is inclined in the longitudinal direction of the rack shaft. The direction of inclination of the pinion shaft is opposite between the right-hand drive vehicle and the left-hand drive vehicle. However, since the rack is “quickly toothed”, it can be shared by right-hand drive cars and left-hand drive cars. Management of parts of the steering device becomes easy and productivity is increased.

1 is a schematic diagram of a vehicle steering apparatus according to a first embodiment of the present invention. It is sectional drawing which shows the assembly structure of the pinion shaft shown in FIG. 1, a rack and pinion mechanism, a rack shaft, and two rack support parts. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. FIG. 3 is a perspective view showing an assembly configuration of a rack and pinion mechanism, a rack shaft, and two rack support portions shown in FIG. 2. FIG. 5 is a sectional view taken along line 5-5 of FIG. It is the figure which represented typically the relationship between the rack and pinion mechanism shown in FIG. 3, a rack shaft, and an urging | biasing part. It is a figure explaining the effect | action of the steering apparatus for vehicles shown by FIG. It is sectional drawing which shows the assembly structure of the rack and pinion mechanism of the steering apparatus for vehicles of Example 2 which concerns on this invention, a rack shaft, and an urging | biasing part. It is sectional drawing which shows the assembly structure of the rack shaft and rack support part of the steering device for vehicles of Example 2 which concerns on this invention. It is sectional drawing which shows the assembly structure of the rack and pinion mechanism of the steering apparatus for vehicles of Example 3 which concerns on this invention, a rack shaft, and an urging | biasing part. It is sectional drawing which shows the assembly structure of the rack and pinion mechanism of the steering apparatus for vehicles of Example 4 which concerns on this invention, a rack shaft, and an urging | biasing part. It is sectional drawing which shows the assembly structure of the rack shaft and rack support part of the vehicle steering device of Example 5 which concerns on this invention. It is sectional drawing which shows the assembly structure of the rack and pinion mechanism of the steering apparatus for vehicles of Example 6 which concerns on this invention, a rack shaft, and an urging | biasing part. FIG. 14 is a cross-sectional view of the rack shaft shown in FIG. 13. It is sectional drawing which shows the assembly structure of the rack shaft and rack support part of the steering device for vehicles of Example 6 which concerns on this invention. It is a perspective view of the rack axis | shaft of the steering apparatus for vehicles of Example 7 which concerns on this invention. It is a figure which shows the manufacturing method of the rack axis | shaft shown by FIG. FIG. 18 is a cross-sectional view of a pair of split molds for secondary forming for additionally processing the semi-finished rack shaft shown in FIG. 17. It is sectional drawing of the rack guide of the steering device for vehicles of Example 8 which concerns on this invention. FIG. 20 is a cross-sectional view illustrating a configuration in which the rack guide illustrated in FIG. 19 is fitted into a rack guide housing. It is sectional drawing which shows the assembly structure of the rack shaft and rack guide of the vehicle steering device of Example 9 which concerns on this invention. FIG. 22 is a cross-sectional view taken along line 22-22 of FIG. It is sectional drawing which shows the structure which has an O-ring in the rack guide of the vehicle steering device of Example 10 which concerns on this invention. It is sectional drawing which shows the structure which has O-ring offset by the rack guide of the steering apparatus for vehicles of Example 11 which concerns on this invention. It is sectional drawing which shows the assembly structure of the rack shaft and rack guide of the vehicle steering device of Example 11 which concerns on this invention. It is sectional drawing which shows the assembly structure of the rack and pinion mechanism of the vehicle steering device of Example 12 which concerns on this invention, a rack shaft, and an urging | biasing part. It is a perspective view which shows the assembly structure of the rack and pinion mechanism shown in FIG. 26, a rack shaft, and two rack support parts. It is sectional drawing which shows the assembly structure of the rack axis | shaft and rack support part of the vehicle steering device of Example 12 which concerns on this invention. It is a figure explaining the effect | action of the steering apparatus for vehicles shown by FIG. FIG. 30 is a sectional view taken along line 30-30 in FIG. 29. It is sectional drawing which shows the assembly structure which is urging | biasing the pinion of the steering apparatus for vehicles of Example 13 which concerns on this invention by the urging | biasing part in the direction which meshes with a rack. FIG. 32 is a cross-sectional view taken along line 32-32 in FIG. 31. FIG. 32 is a perspective view showing an assembly configuration of a rack and pinion mechanism, a rack shaft, and two rack support portions shown in FIG. 31. It is sectional drawing which shows the assembly structure of the rack shaft and rack support part of the steering device for vehicles of Example 13 which concerns on this invention.

  EMBODIMENT OF THE INVENTION The form for implementing this invention is demonstrated below based on an accompanying drawing.

  A vehicle steering apparatus according to a first embodiment will be described with reference to FIGS.

  As shown in FIG. 1, the vehicle steering apparatus 10 according to the first embodiment has a pinion shaft 14 (rotary shaft 14) connected to a steering wheel 11 via a steering shaft 12 and universal shaft joints 13, 13. A rack shaft 16 is connected to the shaft 14 via a rack and pinion mechanism 15, and left and right steering wheels 21, 21 are connected to both ends of the rack shaft 16 via ball joints 17, 17, tie rods 18, 18 and knuckles 19, 19. Are concatenated.

  According to the vehicle steering device 10 (hereinafter simply referred to as “steering device 10”), the steering torque generated when the driver steers the steering wheel 11 is transmitted from the steering wheel 11 to the rack and pinion mechanism 15 and the left and right steering wheels. It can be transmitted to the left and right steering wheels 21, 21 via the tie rods 18, 18.

  The rack and pinion mechanism 15 includes a pinion 31 formed on the pinion shaft 14 and a rack 32 formed on the rack shaft 16. The pinion 31 and the rack 32 are configured as “helical teeth”. The pinion shaft 14 extends in the vertical direction of the vehicle. The rack shaft 16 is composed of a round bar having a perfect circular cross section extending in the vehicle width direction.

  As shown in FIGS. 2 and 3, the rack shaft 16 has at least a back surface 16 a of a portion where the rack 32 is formed in a substantially arc-shaped cross section. The pinion shaft 14, the rack-and-pinion mechanism 15, and the rack shaft 16 are housed in a housing 41 at least at a substantial part. The housing 41 is an elongated cylindrical member that penetrates in the vehicle width direction and opens upward from the upper end of the longitudinal center. Both ends of the rack shaft 16 extend outward in the vehicle width direction from both ends of the housing 41. A space between both ends of the housing 41 and the left and right tie rods 18 and 18 is covered with boots 42 and 42.

  The pinion shaft 14 has an upper portion and a lower end portion sandwiching the pinion 31 so that the pinion shaft 14 can be rotated by two bearings (an upper first bearing 43 and a lower second bearing 44) mounted in the housing 41. Supported to regulate directional movement. Although the two bearings 43 and 44 are constituted by ball bearings, the second bearing 44 may be a radial bearing such as a needle bearing.

  The steering device 10 includes two rack support portions 50 and 50 positioned on both sides in the longitudinal direction of the rack shaft 16 with respect to the position of the pinion 31 (the meshing position of the pinion 31 and the rack 32). And an urging portion 60 positioned between the rack support portions 50 and 50.

  As shown in FIGS. 2, 4, and 5, the two rack support portions 50 and 50 are members that support the rack shaft 16, and are configured by cylindrical bearings (for example, bushes). Each rack support part 50, 50 is mounted in the housing 41 by press-fitting (interference fitting) or the like, and has perfect circular support holes 51, 51, respectively. The diameters of the support holes 51 and 51 are set slightly larger than the diameter of the rack shaft 16. For this reason, the clearance gap between the rack shaft 16 and each support hole 51 and 51 is few.

  Each rack support portion 50, 50 is preferably made of a material having wear resistance and a low frictional resistance when the rack shaft 16 slides. For example, each rack support 50, 50 is made of a copper-based metal bush having a surface coated with a fluororesin such as polytetrafluethylene resin (abbreviation; PTFE, Teflon (registered trademark)).

  In addition, the rack support portions 50 and 50 may be, for example, a polyacetal resin or a resin containing polyacetal, a polytetrale, or the like when the support rigidity for supporting the rack shaft 16 can be lowered as compared with the copper-based metal. It can be constituted by a resin product such as a fluororesin such as full ethylene resin (abbreviation: PTFE, Teflon (registered trademark)). For example, each rack support part 50 and 50 can be comprised by the resin-made bushes which can be elastically deformed. When such a resin bush is employed, the gap between the rack shaft 16 and each support hole 51, 51 can be set to zero or almost zero.

  As shown in FIG. 2, the length Ler of the rack 32 is set in advance to a fixed range considering the rotation range of the steering wheel 11 (see FIG. 1), for example, about 3.5 rotations. In a state where the rack 32 is positioned at the neutral position of the steering, the length Ler of the rack 32 is distributed substantially evenly on both sides in the axial direction with reference to the meshing position with the pinion 31. Both ends of the rack 32 extend outward in the vehicle width direction from both ends of the housing 41 in a state where the rack 32 is positioned at the neutral position of steering.

  As shown in FIG. 2 and FIG. 4, the two rack support portions 50, 50 are arranged so that the rack 32 of the rack shaft 16 is in the neutral position of steering (the position where the vehicle travels straight). Only the back surface 16a of the formed part is located close to each other so as to be slidably supported in the axial longitudinal direction (vehicle width direction).

  As shown in FIG. 3, the urging direction of the urging unit 60 is set such that the rack shaft 16 can be urged at least in a direction other than the rack 32. More specifically, the urging portion 60 is configured by a rack guide mechanism for pressing the rack shaft 16 against the pinion 31. The urging unit 60 (rack guide mechanism 60) includes a rack guide 61 that contacts the rack shaft 16 from the side opposite to the rack 32, and a compression coil spring that urges the rack guide 61 toward the back surface 16a of the rack shaft 16. 62 and an adjusting bolt 63 for adjusting the urging force by pushing the rack guide 61 through the compression coil spring 62.

  The rack guide 61 has a pressing surface 61a (a supporting surface 61a for supporting the back surface 16a) for pressing the back surface 16a of the portion of the rack shaft 16 where the rack 32 is formed. That is, the rack guide 61 supports the back surface 16a so as to be slidable in the axial longitudinal direction. The rack guide 61 is made of a material having wear resistance and low frictional resistance, such as polyacetal resin or resin containing polyacetal, polytetrafluethylene resin (abbreviation: PTFE, Teflon (registered trademark)), or the like. Resin products such as fluororesin are preferred. Only the portion of the pressing surface 61a of the rack guide 61 can be the above-described resin product. Further, the rack guide 61 can be made of sintered metal.

  Here, the rack shaft 16 is defined as follows based on FIG. In addition, in order to show the structure of the vehicle steering apparatus 10 simply, it demonstrates with FIG. 6 with which the pinion shaft 14 and the rack shaft 16 orthogonally crossed. However, the same configuration is possible even when the pinion shaft 14 is inclined in the longitudinal direction of the rack shaft 16, that is, when the pinion shaft 14 and the rack shaft 16 have a crossing angle that is not orthogonal to each other.

  FIG. 6A is a perspective view schematically showing the rack and pinion mechanism 15 shown in FIG. FIG. 6B is a plan view of the rack and pinion mechanism 15 shown in FIG. FIG. 6C is a cross-sectional view schematically showing the relationship between the rack and pinion mechanism 15 and the rack guide 61 shown in FIG.

  As shown in FIGS. 6A to 6C, a straight line Lc orthogonal to the center line Pr of the rack shaft 16 and orthogonal to the center line Pp of the pinion 31 is referred to as a “pinion orthogonal reference line Lc”. A straight line Lp perpendicular to the center line Pr of the rack shaft 16 and parallel to the center line Pp of the pinion 31 is referred to as a “pinion parallel reference line Lp”. The pinion parallel reference line Lp is orthogonal to the pinion orthogonal reference line Lc.

  As shown in FIGS. 3 and 6, the center line Lg of the rack guide 61 and the center line Lg of the compression coil spring 62 coincide with the pinion orthogonal reference line Lc. The rack guide 61 is a perfect circular columnar member centered on the pinion orthogonal reference line Lc. The rack guide 61 and the compression coil spring 62 are accommodated in a rack guide housing 64. The rack guide housing 64 is formed integrally with the housing 41, and has a circular (perfectly circular) support hole 64a capable of supporting the rack guide 61 slidably along the pinion orthogonal reference line Lc. have. The gap between the outer peripheral surface of the rack guide 61 and the inner surface of the support hole 64a is extremely small enough to allow the rack guide 61 to slide.

  The pressing surface 61 a of the rack guide 61 is formed in a substantially arc-shaped cross section along the back surface 16 a of the rack shaft 16. The pressing surface 61a is formed so as to be in contact with only one surface of the back surface 16a of the rack shaft 16 with respect to the pinion orthogonal reference line Lc. For example, the pressing surface 61a can contact only the upper or lower surface with respect to the horizontal pinion orthogonal reference line Lc.

  More specifically, the arc-shaped radius r1 of the pressing surface 61a is set larger than the arc-shaped radius r2 of the back surface 16a (r1> r2). The center of the radius r2 of the back surface 16a of the rack shaft 16 is located on the pinion orthogonal reference line Lc. On the other hand, the center of the arc-shaped radius r1 of the pressing surface 61a is offset above or below the pinion orthogonal reference line Lc, that is, in the tooth width direction of the rack 32. As a result, the pressing surface 61a contacts only the upper or lower surface of the back surface 16a of the rack shaft 16 with respect to the horizontal pinion orthogonal reference line Lc. 3 and 6, the pressing surface 61a contacts only the surface above the back surface 16a with respect to the pinion orthogonal reference line Lc.

  As shown in FIG. 5, the cross-sectional center Pr (center line Pr) of the rack shaft 16 is along the center line Pp of the pinion 31 with respect to the cross-sectional center Pj (center line Pj) of the two bearings 50 and 50. The rack 32 is offset by an offset amount Δ2 in the tooth width direction. For this reason, the rack shaft 16 has a contact point Qu on an action line connecting the cross-sectional center Pj of each bearing 50, 50 and the cross-sectional center Pr of the rack shaft 16, that is, on the pinion parallel reference line Lp. This contact point Qu is a point where the back surface 16a of the rack shaft 16 contacts the support holes 51 of each bearing. Thus, the contact point Qu of the rack shaft 16 with respect to the support holes 51, 51 of the bearings 50, 50 is at the intersection of the pinion parallel reference line Lp and the support holes 51, 51. As shown in FIGS. 5 and 6C, the contact point Qu is located on the opposite side of the pressing surface 61a of the rack guide 61 with respect to the pinion orthogonal reference line Lc. In FIG. 5, the contact point Qu is below the pinion orthogonal reference line Lc. The reaction force F2 is generated in the direction from the contact point Qu to the pinion parallel reference line Lp. Thus, since the contact point Qu is away from the rack 32 (located at a far site), the rack 32 itself is more reliably supported (contacted) by the two bearings 50 and 50. Can be prevented.

  Next, the operation of the steering device 10 according to the first embodiment will be described with reference to FIGS. 3, 5, and 7 (a) to 7 (c). FIG. 7A schematically illustrates the steering device 10 in a plan view in a state where the rack 32 is located at a neutral position of steering (a position where the vehicle travels straight). FIG. 7B schematically shows the steering device 10 in a plan view in a state where the rack 32 is slid to the right by steering the steering device 10 to the right. FIG. 7C schematically illustrates the steering device 10 in a plan view in a state where the rack 32 is slid to the left by steering the steering device 10 to the left.

  As shown in FIG. 3, the pressing surface 61a of the substantially arc-shaped cross section formed on the rack guide 61 is only on one surface of the back surface 16a of the rack shaft 16 with respect to the pinion orthogonal reference line Lc. In contact. For this reason, the rack guide 61 presses the rack shaft 16 toward the pinion 31 by the urging force F1 of the compression coil spring 62, and the rear surface 16a of the rack shaft 16 is supported by the bearings 50 and 50 as shown in FIG. That is, they are pressed against the rack support portions 50, 50 (preload is applied). As a result, as shown in FIG. 5 and FIG. 7A, a reaction force F2 is generated in each rack support portion 50,50. Each rack support portion 50, 50 supports the back surface 16 a of the rack shaft 16. This rack shaft support configuration corresponds to a so-called “support configuration under a balancing condition in which a beam projects from both sides of two fulcrums and a concentrated load (reaction force of the pinion 31) acts on the longitudinal center of the beam”.

  In this way, the back surface 16a of the rack shaft 16 is reliably supported by the three points of the pinion 31 and the two rack support portions 50 and 50 so that the slide in the longitudinal direction of the shaft is possible and there is no backlash. The In addition, the rack 32 itself is not supported by the rack support portions 50 and 50 unless the bending amount of the rack shaft 16 increases due to an excessive bending force acting on the rack shaft 16 (contacts). Not) There is no need to provide a separate support member for supporting the rack shaft 16, and the support configuration for supporting the rack shaft 16 can be simplified.

  Further, the rack shaft 16 is formed by a pressing surface 61a having an extremely simple configuration that is formed so as to be able to contact only one of the upper and lower surfaces with respect to the substantially horizontal pinion orthogonal reference line Lc (see FIG. 3). Can be pressed toward the pinion 31, and the back surface 16 a of the rack shaft 16 can be pressed against the rack support portions 50, 50. For this reason, it is not necessary to provide a separate component for pressing the back surface 16a of the rack shaft 16 against the rack support portions 50, 50.

  Moreover, only one half (substantially upper half) of the pressing surface 61a contacts the back surface 16a of the rack shaft 16, and the other half (substantially lower half) corresponding to the conventional rack guide is the rack support portion. 50, 50 contact. That is, only the frictional resistance of the conventional rack guide acts. The conventional steering device is subjected to a frictional resistance that is the sum of the frictional resistance of the rack guide and the frictional resistance of the rack support portion that supports the rack shaft in the longitudinal direction. On the other hand, since only the frictional resistance corresponding to the rack guide 61 is applied to the steering device 10 of the first embodiment, the frictional resistance when the rack shaft 16 slides can be suppressed.

  Further, the rack guide 61 has a configuration of only the upper half, and the lower half is not necessary, so that the weight can be reduced. Since the rack support portions 50 and 50 have a simple cylindrical configuration, the rack support portions 50 and 50 are lightweight and hardly increase in the weight of the steering device 10 as a whole.

  Further, since the rack shaft 16 can be shortened, the bending rigidity of the rack shaft 16 is increased. For this reason, the deflection angle of the rack shaft 16 in the rack support portions 50 and 50 is reduced, and the contact state between the rack shaft 16 and the support holes 51 and 51 of the rack support portions 50 and 50 becomes extremely good. Although the rack shaft 16 is shortened and the distance between the rack support portions 50, 50 is shortened, the reaction force of the rack support portions 50, 50 due to the bending force acting on the rack shaft 16 is increased, but each support hole The contact surfaces 51 and 51 can be used effectively. For this reason, since it is not necessary to almost increase the contact area of each rack support part 50 and 50, each rack support part 50 and 50 does not enlarge.

  Further, the two rack support portions 50, 50 can support only the back surface 16a of the portion where the rack 32 is formed on the rack shaft 16, and are positioned close to each other. Since each rack support part 50 and 50 is located in the range of the length of the rack 32, the full length of the rack shaft 16 can be shortened compared with the conventional one located outside the range. For this reason, the rack and pinion mechanism 15 can be reduced in size in the longitudinal direction of the rack 32. Since the housing 41 (see FIG. 3) for housing the rack and pinion mechanism 15 can also be reduced in size, the steering device 10 can be reduced in size and weight.

  Furthermore, the tie rods 18 and 18 connected to the rack shaft 16 can be set longer because the rack shaft 16 is shorter than the conventional one. For this reason, the freedom degree of design of the steering apparatus 10 and the vehicle which mounts this steering apparatus 10 can be raised. For example, the design freedom of the suspension geometry formed by the tie rods 18 and 18 of the steering device 10 and the suspension device (not shown) can be increased.

  In particular, when such a steering device 10 is mounted on a small vehicle having a small vehicle width, restrictions on arrangement are small. In addition, if the tie rods 18 and 18 are set long, the influence of the toe change can be suppressed when the left and right steering wheels 21 and 21 bump or rebound. As a result, the controllability of the vehicle can be improved.

  Furthermore, since the rack shaft 16 is shortened, the tie rods 18 and 18 can be set longer. Therefore, the inclination angle φ (also referred to as tension angle φ) of the tie rods 18 and 18 with respect to the rack shaft 16 can be set small. Therefore, as shown in FIGS. 7B and 7C, when the rack shaft 16 is slid in the vehicle width direction, a force fb (bending force fb) acting in a direction perpendicular to the rack shaft 16 is obtained. ) Is small. Since the bending force fb is small, the bending moment generated on the rack shaft 16 is small. Therefore, the bending strength of the rack shaft 16 can be sufficiently increased and the deflection of the rack shaft 16 can be suppressed. Since the deflection of the rack shaft 16 is small, the accuracy of the turning angle of the left and right steering wheels 21 and 21 during steering can be increased. In addition, the meshing state of the rack 32 with the pinion 31 can be kept good, and as a result, the durability of the rack and pinion mechanism 15 can be sufficiently ensured.

  In general, when long tie rods 18 and 18 are used, the steering geometry is set so that the axial force (thrust, axial force) acting on the rack shaft 16 can be reduced, particularly in a steering region where the steering angle is large. Is easy. That is, it is possible to set so that the arrangement relationship (steering geometry) between the rack shaft 16, the tie rods 18, 18 and the knuckles 19, 19 in a steering region where the steering angle is large is good. As an example of use in a steering region where the steering angle is large, for example, when steering a stopped vehicle, there is a so-called stationary steering.

  By reducing the thrust acting on the rack shaft 16, the steering torque for steering the steering wheel 11 is reduced. Since the steering torque is small, the load on the rack and pinion mechanism 15 is reduced. Therefore, since the strength and durability of the rack and pinion mechanism 15 can be afforded, the reliability of the rack and pinion mechanism 15 is enhanced.

  Furthermore, when a so-called electric power steering device is adopted in which the auxiliary torque generated by the electric motor in accordance with the steering torque is added to the rack and pinion mechanism 15, the steering torque is small. As a result, the electric motor can be miniaturized. For this reason, the weight of the entire steering apparatus 10 can be reduced, and the power consumption of the steering apparatus 10 can be reduced. Accordingly, the burden on the engine is reduced, and the fuel efficiency of the vehicle equipped with the steering device 10 is increased.

  As shown in FIG. 7A, the vibrations of the respective steering wheels 21 and 21 generated due to disturbance applied to the left and right steering wheels 21 and 21 during traveling, for example, road surface unevenness, are 21 and 21 are transmitted to the rack shaft 16 through the tie rods 18 and 18.

  On the other hand, in the first embodiment, when the rack 32 is located near the neutral position of steering, preload is applied to the left and right rack support portions 50, 50 from the back surface 16a of the rack shaft 16. For this reason, there is no gap between the back surface 16 a of the rack shaft 16 and the rack support portions 50, 50. Since the preload is applied and there is no gap, it is possible to sufficiently prevent the sound that the rear surface 16a of the rack shaft 16 hits the rack support portions 50 and 50, that is, the hitting sound, due to the vibration.

  For example, during the right steering shown in FIG. 7B or the left steering shown in FIG. 7C, the direction of the reaction force received by the rack support portions 50, 50 is the back surface 16a of the rack shaft 16. The preload is applied to the left and right rack support portions 50, 50. For this reason, when the right steering and the left steering are reversed, it is possible to sufficiently prevent the occurrence of a sound (sounding sound) in which the back surface 16a of the rack shaft 16 hits the rack support portions 50 and 50.

  Moreover, since the rack shaft 16 is shorter than the conventional one, it is lightweight. Even if a large disturbance exceeding the preload is transmitted to the rack shaft 16, the hitting sound can be suppressed. Therefore, noise transmitted from the steering device 10 to the vehicle compartment can be sufficiently prevented, and as a result, the environment in the vehicle compartment can be further enhanced.

  A vehicle steering apparatus according to a second embodiment will be described with reference to FIGS. FIG. 8 is shown corresponding to FIG. FIG. 9 is shown corresponding to FIG. The vehicle steering apparatus 10A according to the second embodiment includes the rack shaft 16, the rack support portion 50, and the biasing portion 60 (rack guide mechanism 60) shown in FIGS. 3 and 5 as shown in FIGS. Since the rack shaft 16A, the rack support portion 50A, and the biasing portion 60A (rack guide mechanism 60A) shown in FIG. 1 are changed, the other configurations are the same as those shown in FIGS. Is omitted.

  Specifically, the rack shaft 16A according to the second embodiment has a back surface 16Aa on the surface on which the rack 32 is formed, having a substantially tapered cross section when viewed from the longitudinal direction of the shaft. The taper of the back surface 16Aa is formed symmetrically with respect to the pinion orthogonal reference line Lc. For this reason, the entire cross section of the rack shaft 16A is also vertically symmetrical with respect to the pinion orthogonal reference line Lc.

  The rack guide mechanism 60A (biasing portion 60A) includes a rack guide 61A that contacts the rack shaft 16A from the side opposite to the rack 32, a compression coil spring 62, and an adjustment bolt 63. The pressing surface 61Aa of the rack guide 61A is formed as an inclined surface along the back surface 16Aa of the rack shaft 16A. The pressing surface 61Aa is formed so as to be in contact with only one surface of the back surface 16Aa of the rack shaft 16 with respect to the pinion orthogonal reference line Lc. For example, the pressing surface 61Aa can contact only the upper or lower surface with respect to the horizontal pinion orthogonal reference line Lc. In FIG. 8, the pressing surface 61Aa is in contact with only the upper surface with respect to the pinion orthogonal reference line Lc.

  As shown in FIG. 9, the two rack support portions 50 </ b> A and 50 </ b> A are members that support the back surface 16 </ b> Aa of the rack shaft 16 </ b> A and are configured by protruding portions that protrude into the housing 41. The support surface 50Aa of the rack support portion 50A is an inclined surface corresponding to the substantially tapered back surface 16Aa. Since the pressing surface 61Aa (see FIG. 8) is in contact with only the upper surface with respect to the pinion orthogonal reference line Lc, the support surface 50Aa is on the opposite side, that is, the lower surface with respect to the pinion orthogonal reference line Lc. Only touching. Each rack support portion 50A, 50A is preferably made of a material having low frictional resistance when the pinion shaft 14 slides.

  According to the second embodiment, the same operations and effects as those of the first embodiment are exhibited. Further, by using the rack shaft 16A having such a cross-sectional shape, the bending rigidity of the rack shaft 16A is improved and the deflection angle of the rack shaft 16A is reduced. As a result, the contact state of the contact portions 16Aa and 50Aa (the back surface 16Aa and the support surface 50Aa) between the rack shaft 16A and the rack support portions 50A and 50A is further improved. As a result, there is a margin in the bearing capacity (allowable load) of each rack support 50A, 50A. Therefore, if the bearing capacity is equal to that of the first embodiment, the rack support portions 50A and 50A can be downsized. Further, since the amount of deflection of the rack shaft 16A is reduced, the accuracy of the turning angle of the steering wheels 21 and 21 (see FIG. 1) generated by the deflection of the rack 32 is improved, leading to the improvement of maneuverability.

  A vehicle steering apparatus according to a third embodiment will be described with reference to FIG. FIG. 10 is shown corresponding to FIG. In the vehicle steering apparatus 10B according to the third embodiment, the urging unit 60 (rack guide mechanism 60) illustrated in FIG. 3 is changed to the urging unit 60B (rack guide mechanism 60B) illustrated in FIG. Since the other configuration is the same as the configuration shown in FIGS. 1 to 7, the description is omitted.

  Specifically, the rack guide mechanism 60 </ b> B (urging portion 60 </ b> B) of the third embodiment includes a rack guide 61 </ b> B that contacts the rack shaft 16 from the side opposite to the rack 32, a compression coil spring 62, and an adjustment bolt 63. The pressing surface 61Ba of the rack guide 61B is formed in a substantially arc-shaped cross section along the back surface 16a of the rack shaft 16. The pressing surface 61Ba is formed so as to be in contact with only one surface of the back surface 16a of the rack shaft 16 with respect to the pinion orthogonal reference line Lc. For example, the pressing surface 61Ba can contact only the upper or lower surface with respect to the horizontal pinion orthogonal reference line Lc.

  In the rack guide mechanism 60B, the center line Lg of the rack guide 61B and the center line Lg of the compression coil spring 62 are offset above or below the pinion orthogonal reference line Lc by the offset amount δ1. That is, the center of the pressing surface 61Ba is offset in the tooth width direction of the rack 32 with respect to the center of the rack shaft 16. The arc-shaped radius r3 of the pressing surface 61Ba is set larger than the arc-shaped radius r2 of the back surface 16a (r3> r2).

  More specifically, the center of the radius r2 of the back surface 16a of the rack shaft 16 is located on the pinion orthogonal reference line Lc. On the other hand, the center of the arc-shaped radius r3 of the pressing surface 61Ba is offset above or below the pinion orthogonal reference line Lc, that is, in the tooth width direction of the rack 32. As a result, the pressing surface 61Ba contacts only the upper or lower surface with respect to the horizontal pinion orthogonal reference line Lc. In FIG. 10, the pressing surface 61Ba is in contact with only the upper surface with respect to the pinion orthogonal reference line Lc.

  According to the third embodiment, the same operations and effects as those of the first embodiment are exhibited. Furthermore, according to the third embodiment, the arc-shaped radius r3 of the pressing surface 61Ba of the rack guide 61B is set larger than the arc-shaped radius r2 of the back surface 16a of the rack shaft 16, and the center of the pressing surface 61Ba is The rack shaft 16 is pressed toward the pinion 31 by the pressing surface 61Ba having a very simple configuration that is offset in the tooth width direction of the rack 32 with respect to the center of the rack shaft 16, and the back surface 16a of the rack shaft 16 is It can be pressed against the rack support portions 50, 50. Moreover, it is not necessary to provide a separate support member for supporting the rack shaft 16.

  By the way, in the configuration of the first embodiment shown in FIG. 3, even if the rack guide 61 is installed upside down with respect to the rack guide housing 64, the frictional resistance of the steering device 10 (see FIG. 1) does not change. Cannot be detected.

  Further, in the configuration of the second embodiment shown in FIGS. 8 and 9, when the rack guide 61A is assembled upside down with respect to the rack guide housing 64, the rack shaft 16A is arranged in the direction where the rack support portions 50A and 50A are not present. It will be pushed.

  On the other hand, in the configuration of the third embodiment, even if the rack guide 61B is assembled upside down with respect to the rack guide housing 64, the direction of the force is the same, there is no fear of being assembled incorrectly, and productivity is increased.

  A vehicle steering apparatus according to Embodiment 4 will be described with reference to FIG. FIG. 11 is shown corresponding to FIG. In the vehicle steering apparatus 10C of the fourth embodiment, the urging unit 60 (rack guide mechanism 60) shown in FIG. 3 is changed to the urging unit 60C (rack guide mechanism 60C) shown in FIG. Since the other configuration is the same as the configuration shown in FIGS. 1 to 7, the description is omitted.

  Specifically, the rack guide mechanism 60 </ b> C (biasing portion 60 </ b> C) of the fourth embodiment includes a rack guide 61 </ b> C that contacts the rack shaft 16 from the side opposite to the rack 32, a compression coil spring 62, and an adjustment bolt 63. The pressing surface 61Ca of the rack guide 61C is formed in a substantially arc-shaped cross section along the back surface 16a of the rack shaft 16. The center line Lg of the rack guide 61C and the center line Lg of the compression coil spring 62 pass through the cross-sectional center (center line Pr) of the rack shaft 16, and are inclined in the axial direction of the pinion 31 with respect to the pinion orthogonal reference line Lc. Just leaning. The shape of the pressing surface 61Ca is not a Gothic arch shape but a single arc shape. The arc-shaped radius r4 of the pressing surface 61Ca is set to be the same as or slightly larger (substantially the same) as the arc-shaped radius r2 of the back surface 16a (r4 ≧ r2).

  According to the fourth embodiment, the same operations and effects as those of the first embodiment are exhibited. Similarly to the third embodiment, even if the rack guide 61C is assembled upside down with respect to the rack guide housing 64, the direction of the force is the same, there is no fear that it will be assembled incorrectly, and the productivity is increased. Furthermore, according to the fourth embodiment, the center line Lg of the rack guide 61C passes through the cross-sectional center of the rack shaft 16, and is inclined by the inclination angle θ in the axial direction of the pinion 31 with respect to the pinion orthogonal reference line Lc. With the rack guide 61C having such an extremely simple configuration, the rack shaft 16 can be pressed toward the pinion 31 and the back surface 16a of the rack shaft 16 can be pressed against the rack support portions 50 and 50. Moreover, it is not necessary to provide a separate support member for supporting the rack shaft 16.

  A vehicle steering apparatus according to Embodiment 5 will be described with reference to FIG. FIG. 12 is shown corresponding to FIG. The vehicle steering apparatus 10D of the fifth embodiment is characterized in that the offset configuration of the rack shaft 16 with respect to the bearings 50, 50 shown in FIG. 5 is changed, and the basic configuration is the embodiment shown in FIG. Same as Example 4. As described above, the other configurations of the fifth embodiment are the same as those illustrated in FIGS. 1 to 7 and FIG.

  Specifically, the cross-sectional center Pr (center line Pr) of the rack shaft 16 of the fifth embodiment is pinion 31 (see FIG. 6) with respect to the cross-sectional center Pj (center line Pj) of each rack support 50, 50. Is offset by an offset amount Δ1 in a direction away from the rack 32 and offset by an offset amount Δ2 in the tooth width direction of the rack 32. As a result, as shown in FIG. 12, the rack shaft 16 has a contact point Qw on the action line WL connecting the cross-sectional center Pj of the rack support portions 50 and 50 and the cross-sectional center Pr of the rack shaft 16. A reaction force F2 is generated in the direction of the action line WL. Each rack support portion 50, 50 supports the back surface 16 a of the rack shaft 16. This rack shaft support configuration corresponds to a so-called “support configuration under a balancing condition in which a beam projects from both sides of two fulcrums and a concentrated load (reaction force of the pinion 31) acts on the longitudinal center of the beam”. The offset amount Δ1 may not be offset. In that case, a reaction force F2 is generated from the rack lower point Qu.

  In this way, the back surface 16a of the rack shaft 16 is reliably supported by the three points of the pinion 31 and the two rack support portions 50 and 50 so as to be slidable in the longitudinal direction of the shaft. Moreover, the rack 32 itself can be more reliably prevented from being supported (contacted) by the two bearings 50 and 50.

  A vehicle steering apparatus according to Embodiment 6 will be described with reference to FIGS. FIG. 13 is shown corresponding to FIG. FIG. 14 shows a cross-sectional shape of the rack shaft 16E according to the sixth embodiment which is cut into a ring. FIG. 15 is a view corresponding to FIG. 12, and shows a configuration in which the rack shaft 16E is supported by two bearings 50 and 50. FIG.

  The vehicle steering apparatus 10E according to the sixth embodiment is characterized in that the rack shaft 16 shown in FIGS. 11 and 12 is changed to the rack shaft 16E shown in FIGS. The urging unit 60C (rack guide mechanism 60C) is substantially the same as the configuration of the fourth embodiment shown in FIG. 11, but the configuration of the first or third embodiment may be used. The other configuration of the vehicle steering device 10E is the same as the configuration shown in FIGS.

  As shown in FIG. 14, the rack shaft 16 </ b> E is a forged product, except for a portion having the rack 32, on the same circumference of the outer circumferential surface (a perfect circular circumferential surface shown by an imaginary line in FIG. 14 16Es) are formed with two rack opposite side convex portions 16Ea and 16Eb and two rack approaching side convex portions 16Ec and 16Ed that can be supported by two bearings 50 and 50 (see FIG. 15). Has been. Each of these convex portions 16Ea, 16Eb, 16Ec, 16Ed is a projecting portion having an arcuate cross section projecting radially outward from the circumferential surface 16Es, and extends in the longitudinal direction of the shaft over the entire length of the rack shaft 16E.

  The two rack opposite-side convex portions 16Ea and 16Eb are located on the opposite side of the rack 32 with respect to the pinion parallel reference line Lp and on both sides of the pinion orthogonal reference line Lc. That is, the rack opposite side convex portions 16Ea and 16Eb are located on the back surface 16Ee of the portion where the rack 32 of the rack shaft 16E is formed. On the other hand, the two rack approaching side convex portions 16Ec and 16Ed are located between the pinion parallel reference line Lp and the rack 32, and are located on both sides of the pinion orthogonal reference line Lc.

  For example, the radius r11 of the rack-opposite convex portions 16Ea and 16Eb having an arcuate cross section is set to be smaller than the radius r12 of the perfect circular circumferential surface 16Es. The center Pd of the radius r11 of the rack opposite-side convex portions 16Ea and 16Eb is offset by an offset amount Δ11 on the opposite side of the rack 32 with respect to the pinion parallel reference line Lp, and only by a both-side offset amount Δ12 of the pinion orthogonal reference line Lc. It is offset.

  Here, in FIG. 14, the rack opposite side convex portion 16 </ b> Ea in the upper right of the drawing is referred to as “first rack opposite side convex portion 16 </ b> Ea”. The rack opposite-side convex portion 16Eb in the lower right of the drawing is referred to as a “second rack opposite-side convex portion 16Eb”. The rack approaching side convex part 16Ec at the lower left of the drawing is referred to as a “first rack approaching side convex part 16Ec”. The rack approaching side convex portion 16Ed at the upper left of the drawing is referred to as a “second rack approaching side convex portion 16Ed”.

  As shown in FIG. 15, the bearings 50, 50 support the second rack opposite side convex portion 16 </ b> Eb so as to be slidable in the longitudinal direction of the rack shaft 16 </ b> E.

  According to the sixth embodiment, the same operations and effects as those of the first embodiment are exhibited. Furthermore, in the sixth embodiment, the rack shaft 16E is opposite to the first rack and can be supported by the cylindrical bearings 50 and 50 on the same circumference of the outer circumferential surface except for the portion having the rack 32. Side convex portions 16Ea and second rack opposite side convex portions 16Eb are formed. The two rack opposite-side convex portions 16Ea and 16Eb are located on the opposite side of the rack 32 with respect to the pinion parallel reference line Lp and on both sides of the pinion orthogonal reference line Lc. Further, the center line Lg of the rack guide 61C passes through the cross-sectional center Pr (center line Pr) of the rack shaft 16, and is inclined by the inclination angle θ in the axial direction of the pinion 31 with respect to the pinion orthogonal reference line Lc.

  For this reason, each bearing 50, 50 does not support the entire back surface of the rack shaft 16E but can support at least one of the two rack-opposite convex portions 16Ea, 16Eb. For example, in the sixth embodiment shown in FIG. 13, the rack guide 61C is inclined upward with respect to the pinion orthogonal reference line Lc. For this reason, normally, the second rack opposite-side convex portion 16Eb positioned below the pinion orthogonal reference line Lc is supported by the bearings 50 and 50, respectively.

  In general, when steering during traveling, the frictional force between the road surface and the steering wheels 21 and 21 (see FIG. 1) is small, so a relatively small steering force is sufficient. At this time, the bending force fb (see FIG. 7) applied to the rack shaft 16E out of the reaction forces acting from the tie rods 18 and 18 via the knuckles 19 and 19 from the steering wheels 21 and 21 is small. The pressing force for pressing 16Ee against the bearings 50 and 50 is small. In this case, the rack-opposite convex portion located on the opposite side of the rack guide 61C with respect to the pinion orthogonal reference line Lc is supported by each bearing. Of the rack shaft 16E, the support points supported by the bearings 50 are determined reliably.

  When the bending force fb (see FIG. 7) acting on the rack shaft 16E out of the reaction forces input from the tie rods 18 and 18 via the knuckles 19 and 19 from the steering wheels 21 and 21, the rear surface 16Ee of the rack shaft 16E is increased. The pressing force that presses the bearings 50 and 50 toward the bearings 50 also increases. In this case, both the two rack-opposite convex portions 16Ea and 16Eb located on both sides with respect to the pinion orthogonal reference line Lc are supported by the bearings 50 and 50, and each bearing 50 caused by the lateral load fb. , 50 is distributed in two places. For this reason, since an excessive steering force does not act on one point of each bearing 50 and 50, durability of the rack shaft 16E and the bearings 50 and 50 increases.

  Further, in the sixth embodiment, the first rack approaching side convex portion 16Ec and the second rack approaching side convex portion 16Ed that can be supported by the two bearings 50 and 50 on the same circumference of the outer peripheral surface of the rack shaft 16E. Is formed. The two rack approaching side convex portions 16Ec and 16Ed are located between the pinion parallel reference line Lp and the rack 32, and are located on both sides of the pinion orthogonal reference line Lc.

  When steering a stopped vehicle, so-called stationary steering, the frictional force between the road surface and the steering wheels 21 and 21 (see FIG. 1) is large. In other words, since the road surface reaction force is increased, a larger steering force is required. A larger steering force is transmitted from the pinion 31 to the rack 32. The rack shaft support configuration is a configuration in which the rack shaft 16E projects from both sides of the two bearings 50 and 50, and a concentrated load (pressing force of the pinion 31) acts on the longitudinal center of the rack shaft 16E. A larger pressing force acts on the longitudinal center of the rack shaft 16E from the pinion 31, whereby both sides of the rack shaft 16E try to bend toward the rack 32 side. For this reason, the rack 32 formed on the rack shaft 16E tends to contact the bearings 50 and 50. However, in this case, since at least one of the two rack approaching side convex portions 16Ec and 16Ed contacts the bearings 50 and 50 first, the rack 32 does not contact the bearings 50 and 50. Therefore, the rack shaft 16E can slide more smoothly.

  With such a configuration, it is not necessary to offset the center Pj of the housing 40 and the bearings 50 and 50. Further, the center of the arc of the pressing surface 61Ca of the rack guide 61C can be single. For this reason, the productivity of the vehicle steering apparatus 10E increases.

  A vehicle steering apparatus according to a seventh embodiment will be described with reference to FIGS. The vehicle steering apparatus 10F of the seventh embodiment is characterized in that the rack shaft 16E shown in FIG. 14 is changed to the rack shaft 16F shown in FIG. Since the configuration is the same as that shown in FIG. 7 and FIGS.

  As FIG. 16 shows, the rack shaft 16F of Example 7 is comprised by carrying out the plastic working of the hollow material. This hollow material consists of metal pipes, such as a steel pipe. The two rack opposite side convex portions 16Ea and 16Eb and the two rack approaching side convex portions 16Ec and 16Ed are formed by extrusion from the inside of the hollow material 16F (rack shaft 16F) toward the radially outward direction. Part.

  An example of a method for manufacturing the rack shaft 16F will be described as follows. First, a pipe material having a predetermined length made of a steel pipe is prepared (first step). Next, the middle part of the pipe material is flattened by a press to form a flat portion (second step). Next, a rack is formed by subjecting the flat portion to plastic processing, for example, rolling (third step). 17 and 18 show a semi-finished rack shaft 16Fh (semi-finished rack shaft 16Fh) in which a rack is formed on the pipe material as described above.

  The procedure from the first step to the third step, that is, the manufacturing method for manufacturing the semi-finished rack shaft 16Fh from the pipe material is disclosed in, for example, Japanese Patent Publication No. 3-5892 and Japanese Patent Application Laid-Open No. 2001-163228. As described above, there are various types, and an arbitrary method can be adopted, and thus detailed description thereof is omitted.

  Next, as shown in FIGS. 17 and 18, a pair of secondary forming split dies 71 </ b> A and 71 </ b> B and a punch 72 for additionally processing the semi-finished rack shaft 16 </ b> Fh are prepared. The pair of split molds 71A, 71B are combined to form a cylindrical shape as a whole, and the inner peripheral surface has recesses 71a for forming the protrusions 16Ea, 16Eb, 16Ec, 16Ed shown in FIG. 71b, 71c, 71d. On the other hand, on the outer peripheral surface of the punch 72, convex portions 72a, 72b, 72c, 72d for forming the convex portions 16Ea, 16Eb, 16Ec, 16Ed are formed.

  After the semi-finished rack shaft 16Fh is set in the pair of split molds 71A and 71B and clamped, the punch 72 is forcibly press-fitted into the semi-finished rack shaft 16Fh, whereby the outer peripheral surface of the semi-finished rack shaft 16Fh. Each convex part 16Ea, 16Eb, 16Ec, 16Ed is formed. As a result, as shown in FIG. 16, the rack shaft 16F having the convex portions 16Ea, 16Eb, 16Ec, and 16Ed is completed.

  In the above, an example of division processing has been shown for the sake of explanation. Actually, in order to improve the accuracy of the rack tooth profile after molding and the convex portions 16Ea, 16Eb, 16Ec, and 16Ed, the process of the third step and the convex portions In the molding process of the portions 16Ea, 16Eb, 16Ec, and 16Ed, it is possible to perform simultaneous molding by providing the punch 72 with a convex portion for a rack tooth forming mold.

  According to the seventh embodiment, the same operations and effects as those of the sixth embodiment are exhibited. Furthermore, in Example 7, the two rack opposite-side convex portions 16Ea and 16Eb and the two rack-accessing side convex portions 16Ec and 16Ed are extruded from the inside of the rack shaft 16F made of a hollow material toward the radially outer side. It is formed by being. For this reason, each surface of rack opposite side convex part 16Ea, 16Eb and rack approaching side convex part 16Ec, 16Ed becomes smoother (surface roughness becomes favorable). Therefore, the frictional resistance of the convex portions 16Ea to 16Ed with respect to the bearings 50 and 50 when the rack shaft 16F slides can be suppressed.

  Moreover, each rack opposite side convex part 16Ea, 16Eb and each rack approaching side convex part 16Ec, 16Ed increase hardness by the work hardening by cold forging. Thereby, it is possible to effectively increase the hardness of only the rack opposite side convex portions 16Ea and 16Eb and the rack approaching side convex portions 16Ec and 16Ed that are in contact with the bearings 50 and 50, that is, only the sliding portions. As a result, each rack opposite convex part 16Ea, 16Eb and each rack approaching side convex part 16Ec, 16Ed can reduce the abrasion by sliding.

  Further, since the weight of the rack shaft 16F is reduced, the hitting sound generated due to the disturbance from the steering wheels 21 and 21 (see FIG. 1) is reduced. Moreover, the preload load of the compression coil spring 62 of the rack guide mechanism 60C (see FIG. 13) can be reduced by reducing the weight of the rack shaft 16F. As a result, the frictional resistance of the steering device 10F is reduced, and good steering characteristics can be obtained.

  A vehicle steering apparatus according to an eighth embodiment will be described with reference to FIGS. 19 and 20. The vehicle steering apparatus 10G according to the eighth embodiment includes the rack guide 61 of the urging unit 60 (rack guide mechanism 60) shown in FIGS. 3 and 6 and the urging unit 60G (see FIG. 19 and FIG. 20). The rack guide mechanism 60G) is changed to the rack guide 61G, and the other configurations are the same as those shown in FIGS.

  In general, a static frictional force is generated between the outer surface of the rack guide 61G and the inner surface of the support hole 64a (wall surface forming the hole). On the other hand, when the rack shaft 16 (see FIG. 3) slides, a dynamic friction force larger than the static friction force is generated between the rack shaft 16 and the rack guide 61G. For this reason, due to the difference in magnitude between the static frictional force and the dynamic frictional force when the rack shaft 16 slides, the rack guide 61G has a force to swing (swing) around the pinion orthogonal reference line Lc. A so-called rocking force can act. As a result, the rack guide 61G tries to vibrate intermittently (self-excited vibration). Such a phenomenon is disadvantageous in maintaining a smooth sliding operation of the rack shaft 16 and maintaining a good meshing state of the rack 32 with the pinion 31.

  On the other hand, in the eighth embodiment, the rack guide 61G includes a swing restricting portion 81G for restricting the swing of the rack guide 61G with respect to the pinion orthogonal reference line Lc. For this reason, when a swinging force that swings around the pinion orthogonal reference line Lc is applied to the rack guide 61G fitted in the support hole 64a, the swing guide 61G swings the rack guide 61G. Can be regulated. Therefore, the smooth sliding operation of the rack shaft 16 can be maintained, the good meshing state of the rack 32 with the pinion 31 can be sufficiently maintained, and the durability of the rack and pinion mechanism 15 can be enhanced. Furthermore, the durability of the rack guide 61G itself can be enhanced.

  Further, the swing restricting portion 81G includes at least two convex portions 81Ga and 81Ga formed in the circumferential direction of the outer peripheral surface of the rack guide 61G. The convex portions 81Ga and 81Ga are formed in an arc shape having a radius r21 when the rack guide 61G is viewed along the pinion orthogonal reference line Lc. The radius r21 of each convex part 81Ga and 81Ga is smaller than the radius r22 of the rack guide 61G. In this way, the swing restricting portion 81G can be configured extremely simply by providing at least two convex portions 81Ga and 81Ga on the outer peripheral surface of the rack guide 61G. In addition, it is extremely easy to form the convex portions 81Ga and 81Ga on the rack guide 61G by configuring the rack guide 61G with sintered metal, resin, or the like.

  According to the eighth embodiment, the same operations and effects as those of the first embodiment are exhibited.

  A vehicle steering apparatus according to Embodiment 9 will be described with reference to FIGS. 21 and 22. The vehicle steering apparatus 10H according to the ninth embodiment includes a rack guide 61G and a swing restricting portion 81G of the urging portion 60G (rack guide mechanism 60G) shown in FIGS. 19 and 20, as shown in FIGS. The biasing portion 60H (rack guide mechanism 60H) is changed to a rack guide 61H and a swing restricting portion 81H. Other configurations are shown in FIGS. 1 to 7, 19 and 20 above. Since it is the same as the configuration, the description is omitted.

  Specifically, the rack guide 61H of the ninth embodiment includes a swing restricting portion 81H for restricting the swing of the rack guide 61H with respect to the pinion orthogonal reference line Lc. The swing restricting portion 81H is formed by a filling layer 81Ha having viscoelasticity such as liquid packing, which is filled in a gap between the outer peripheral surface of the rack guide 61H and the inner peripheral surface of the support hole 64a of the rack guide housing 64. It is configured. By simply providing the filling layer 81Ha in the gap, the swing restricting portion 81H can be configured extremely simply.

  A vehicle steering apparatus according to Embodiment 10 will be described with reference to FIG. The vehicle steering apparatus 10I according to the tenth embodiment includes a rack guide 61H and a swing restricting portion 81H of the biasing portion 60H (rack guide mechanism 60H) shown in FIGS. The biasing portion 60I (rack guide mechanism 60I) is characterized in that it is changed to a rack guide 61I and a swing restricting portion 81I, and the other configurations are the same as those shown in FIGS. .

  Specifically, the rack guide 61I according to the tenth embodiment includes a swing restricting portion 81I for restricting the swing of the rack guide 61I around the pinion orthogonal reference line Lc. The rack guide 61 </ b> I has an annular groove 61 </ b> Ia for mounting the O-ring 82 on the outer peripheral surface and is housed in the rack guide housing 64. The annular groove 61Ia can be provided, for example, by cutting the rack guide 61I. The rack guide housing 64 is formed with a support hole 64a that slidably supports the rack guide 61I on which the O-ring 82 is mounted.

  The swing restricting portion 81I is configured by an O-ring 82 attached to the annular groove 61Ia. The outer peripheral surface of the O-ring 82 is in contact with the inner surface of the support hole 64a throughout. As described above, the swing restricting portion 81I can be configured with an extremely simple configuration in which the O-ring 82 is mounted in the annular groove 61Ia formed on the outer peripheral surface of the rack guide 61I.

  Moreover, the step of forming the annular groove 61Ia on the outer peripheral surface of the rack guide 61I in order to provide the swing restricting portion 81I in the narrow gap between the outer peripheral surface of the rack guide 61I and the inner peripheral surface of the support hole 64a; This can be achieved by a simple process including the process of mounting the O-ring 82 in the annular groove 61Ia and the process of fitting the rack guide 61I with the O-ring 82 mounted into the support hole 64a.

  A vehicle steering apparatus according to Embodiment 11 will be described with reference to FIGS. The vehicle steering apparatus 10J according to the eleventh embodiment includes a rack guide 61I and a swing restricting portion 81I of the biasing portion 60I (rack guide mechanism 60I) shown in FIG. The biasing portion 60J (rack guide mechanism 60J) is characterized by being changed to a rack guide 61J and a swing restricting portion 81J, and the other configurations are the same as those shown in FIG.

  Specifically, the swing restricting portion 81J of the eleventh embodiment is configured by an O-ring 82 attached to the annular groove 61Ia, like the swing restricting portion 81I shown in FIG. Furthermore, the center 61Ib of the annular groove 61Ia of the rack guide 61J of the eleventh embodiment is offset by the offset amount Δ21 with respect to the center line Lg of the rack guide 61J. For this reason, the depth of the annular groove 61Ia differs depending on the circumferential position of the rack guide 61J. Accordingly, the amount of protrusion of the O-ring 82 fitted in the annular groove 61Ia from the outer peripheral surface of the rack guide 61J varies depending on the position of the rack guide 61J in the circumferential direction. The direction of the offset is opposite to the portion where the pressing surface 61a contacts the back surface 16a of the rack shaft 16 with respect to the center line Lg of the rack guide 61J.

  In this way, when the rack guide 61J is fitted in the support hole 64a, the contact pressure of the O-ring 82 against the inner peripheral surface of the support hole 64a depends on the portion of the outer peripheral surface of the O-ring 82. Different. That is, the contact pressure varies in the circumferential direction of the O-ring 82. Since the contact pressure varies depending on the portion of the outer peripheral surface of the O-ring 82, it is possible to further restrict the rack guide 61J from swinging around the pinion orthogonal reference line Lc. For this reason, the holding performance for holding the rack guide 61J in an appropriate position by the rack guide housing 64 is enhanced. As a result, the smooth sliding operation of the rack shaft 16 can be maintained, and the good meshing state of the rack 32 with the pinion 31 can be sufficiently maintained. The vehicle steering device 10 </ b> J can ensure a good steering interval with no response delay in the operation of the rack and pinion mechanism 15.

  Further, the offset direction of the annular groove 61Ia is opposite to the portion where the pressing surface 61a contacts the back surface 16a of the rack shaft 16 with respect to the center line Lg of the rack guide 61J. The groove depth on the part side where the pressing surface 61a contacts the back surface 16a is the largest with respect to the center line Lg. For this reason, when the rack guide 61J is fitted into the support hole 64a, the elastic deformation amount of the O-ring 82 at the portion where the groove depth is large is large. The O-ring 82 has a large spring characteristic at a portion where the amount of elastic deformation is large.

  Moreover, since the O-ring 82 is mounted offset to the rack guide 61J, it is easy to visually confirm the fitting direction when the rack guide 61J is fitted into the support hole 64a. For this reason, the assembly reliability of the rack guide 61J increases.

  A vehicle steering apparatus according to Embodiment 12 will be described with reference to FIGS. FIG. 26 is shown corresponding to FIG. FIG. 27 is shown corresponding to FIG. FIG. 28 is shown corresponding to FIG. The vehicle steering apparatus 10K of the twelfth embodiment includes the rack and pinion mechanism 15 and the urging unit 60 (rack guide mechanism 60) shown in FIGS. 3 to 5 and the rack shown in FIGS. The configuration is changed to the and pinion mechanism 15K and the urging unit 60K (rack guide mechanism 60K), and the other configurations are the same as those shown in FIGS.

  Specifically, as shown in FIGS. 26 and 27, the rack and pinion mechanism 15K of the twelfth embodiment includes a pinion 31K and a rack 32K. The pinion 31K and the rack 32K correspond to the pinion 31 and the rack 32 shown in FIG. However, both the pinion 31K and the rack 32K of the twelfth embodiment have a “quick tooth” configuration. That is, the pinion 31K has a “quick tooth” configuration in which the tooth traces are orthogonal to the center line Pp of the pinion 31K. The rack 32K has a “quick tooth” configuration in which the tooth traces are perpendicular to the rack shaft 16 (to the center line Pr of the rack shaft 16). In this case, the pinion shaft 14 and the rack shaft 16 are orthogonal to each other. That is, the pinion shaft 14 is not inclined in the longitudinal direction of the rack shaft 16.

  Note that only the rack 32K may be “immediate teeth”, and the pinion 31K that meshes with the rack 32K may have a “helical tooth” configuration in which the tooth streaks have a predetermined twist angle. In this case, the pinion shafts 14 are so-called obliquely inclined with respect to the longitudinal direction of the rack shaft 16 by an angle corresponding to the twist angle of the “helical teeth” of the pinion 31K. For this reason, the meshing configuration of the pinion 31K and the rack 32K is substantially the same configuration as when both the pinion 31K and the rack 32K are “quick teeth”.

  As shown in FIG. 26, the rack guide mechanism 60K (biasing portion 60K) of the twelfth embodiment includes a rack guide 61K that contacts the rack shaft 16 from the opposite side to the rack 32K, a compression coil spring 62, and an adjustment bolt 63. Consists of.

  The rack guide 61K is a perfect circular columnar member centered on the center line Lg in the sliding direction. A center line Lg in the sliding direction is parallel to the pinion orthogonal reference line Lc. That is, the rack guide 61K is formed in a circular cross section with the center line Lg as a reference. The rack guide 61K and the compression coil spring 62 are accommodated in a rack guide housing 64. The rack guide housing 64 is formed integrally with the housing 41, and has a circular (perfectly circular) support hole 64a capable of slidably supporting the rack guide 61K along the center line Lg. is doing.

  The pressing surface 61Ka of the rack guide 61K is formed in a substantially arc-shaped cross section along the back surface 16a of the rack shaft 16. The pressing surface 61Ka is formed so as to be in contact with only one surface of the back surface 16a of the rack shaft 16 with respect to the pinion orthogonal reference line Lc. For example, the pressing surface 61Ka can contact only the upper or lower surface with respect to the horizontal pinion orthogonal reference line Lc.

  More specifically, the arc-shaped radius r5 of the pressing surface 61Ka is set larger than the arc-shaped radius r2 of the back surface 16a (r5> r2). The center of the radius r2 of the back surface 16a of the rack shaft 16 is located on the pinion orthogonal reference line Lc. On the other hand, the center of the arc-shaped radius r5 of the pressing surface 61Ka is offset above or below the pinion orthogonal reference line Lc, that is, in the tooth width direction (tooth direction) of the rack 32K. As a result, the pressing surface 61Ka contacts only the upper or lower surface of the rear surface 16a of the rack shaft 16 with respect to the horizontal pinion orthogonal reference line Lc. In FIG. 26, the pressing surface 61Ka is in contact with only the surface above the back surface 16a with respect to the pinion orthogonal reference line Lc.

  As described above, since there is a relationship of “r5> r2”, the pressing surface 61Ka contacts the back surface 16a of the rack shaft 16 only at one contact portion Qs. The contact portion Qs of the pressing surface 61Ka with respect to the back surface 16a extends linearly in the axial direction of the rack shaft 16, and is positioned such that the size of the rack guide 61K is maximized in the axial direction of the rack shaft 16. . More specifically, the center line Lg of the rack guide 61K in the sliding direction and the center line Lg of the compression coil spring 62 are offset by an offset amount δ2 in the direction in which the pressing surface 61Ka contacts the back surface 16a with respect to the pinion orthogonal reference line Lc. It is offset. That is, the center of the pressing surface 61Ka is offset from the center of the rack shaft 16 in the tooth width direction of the rack 32K.

  Next, the operation of the twelfth embodiment will be described. As shown in FIGS. 26 and 27, the rack 32 </ b> K is a “quick tooth”. The pinion 31K meshing with the rack 32K is set to “immediate teeth”. Alternatively, the pinion 31K is changed to a “helical tooth”, and the pinion shaft 14 is tilted in the longitudinal direction of the rack shaft 16 by an angle corresponding to the twist angle of the “helical tooth”. It is possible to have a configuration that can be. Thus, the meshing configuration of the pinion 31K and the rack 32K is substantially the same configuration as when both the pinion 31K and the rack 32K are “quick teeth”. For this reason, the direction of the tooth trace of the pinion 31K matches the direction of the tooth trace of the rack 32K.

  Therefore, when an external force (including vibration) in the direction of the tooth trace of the rack 32K is applied to the rack 32K, the rack 32K is easily displaced in the direction of the “tooth trace” (tooth width direction). For example, when the vibration in the direction of the teeth of the rack 32K is transmitted from the outside to the rack 32K, the rack 32K can vibrate in the direction of the teeth. For this reason, the vibration in the tooth trace direction of the rack 32K is converted into the vibration in the rotation direction of the pinion 31K and is not easily transmitted to the steering wheel 11 (see FIG. 1). As a result, the steering feeling given to the driver is enhanced. Further, the “quick tooth” rack 32 </ b> K acts in a restricting direction against vibration in the rotational direction of the pinion 31 </ b> K. For this reason, vibration in the rotational direction of the pinion 31K is difficult to be transmitted to the steering wheel 11. As a result, the steering feeling given to the driver is enhanced.

  As shown in FIG. 7A, when the steering device is not being steered, there is no reaction force transmitted from the steering wheels 21 and 21 to the rack shaft 16 via the tie rods 18 and 18 in accordance with the steering. Therefore, as shown in FIG. 26, the rack guide 61K contacts the back surface 16a of the rack shaft 16 only at one contact portion Qs, and the rack shaft 16 is moved to the pinion 31K by the urging force F1 of the compression coil spring 62. As shown in FIGS. 27 and 28, the back surface 16a of the rack shaft 16 is pressed against the rack support portions 50 and 50 (preload is applied).

  The cross-sectional center Pr (center line Pr) of the rack shaft 16 is in the tooth width direction of the rack 32K along the center line Pp of the pinion 31K with respect to the cross-sectional center Pj (center line Pj) of the two bearings 50 and 50. The offset is offset by Δ2. For this reason, the rack shaft 16 has a contact point Qu on an action line connecting the cross-sectional center Pj of each bearing 50, 50 and the cross-sectional center Pr of the rack shaft 16, that is, on the pinion parallel reference line Lp. The contact point Qu is a point where the back surface 16a of the rack shaft 16 contacts the support holes 51, 51 of the bearings 50, 50. As a result, a reaction force F2 is generated in each bearing 50, 50. Each bearing 50, 50 supports the back surface 16 a of the rack shaft 16. Thus, the back surface 16a of the rack shaft 16 is supported by the three points of the pinion 31 and the two bearings so as to be slidable in the longitudinal direction of the shaft.

  Thereafter, when the steering device is steered, the operation is as follows. FIG. 29 schematically illustrates the steering device 10K in a plan view in a state where the rack 32K is slid to the right by steering the steering device 10K to the right. The tie rods 18, 18 are inclined with respect to the rack shaft 16 in the vehicle longitudinal direction by an inclination angle φ (see FIG. 7A). Therefore, when the rack shaft 16 is slid and displaced in the vehicle width direction, forces fb and fb (bending forces fb and fb) are applied to the rack shaft 16 in a direction perpendicular to the rack shaft 16.

  For example, when the steering device 10K is steered to the right, a road surface reaction force is generated according to the frictional force between the road surface and the steering wheels 21 and 21. This road surface reaction force acts on the rack shaft 16 from the steering wheels 21 and 21 via the tie rods 18 and 18. For this reason, a bending force fb toward the rear of the vehicle acts on the left end of the rack shaft 16, and a bending force fb toward the front of the vehicle acts on the right end of the rack shaft 16.

  When the bending force fb is small, the back surface 16a of the rack shaft 16 is supported by the three points of the pinion 31 and the two bearings 50 and 50 so as to be slidable in the longitudinal direction of the shaft. The frictional force when the rack shaft 16 slides is only a relatively small frictional force corresponding to the urging force F1 that the rack guide 61K shown in FIG. Accordingly, the steering device 10K having a small frictional force and good friction characteristics is obtained.

  On the other hand, even when the bending force fb exceeds the frictional force corresponding to the urging force F1, the bearings 50 and 50 can slide the back surface 16a of the rack shaft 16 in the axial longitudinal direction. It is preferable that it can be supported. That is, the back surface 16a of the rack shaft 16 is supported and the rack 32K is prevented from being affected by the reaction force as much as possible. Therefore, in the twelfth embodiment, when the bending force fb is increased, the statically supported form at three points, that is, the meshing point between the pinion 31K and the rack 32K and the support points by the bearings 50 and 50. Was formed.

  More specifically, the rack shaft 16 that has received a large bending force fb has the left end retracted and the right end advanced (counterclockwise in FIG. 29) with the meshing point of the pinion 31K and the rack 32K as a fulcrum. Try to swing back and forth. That is, the left side of the rack shaft 16 tends to retreat while sliding to the right in the vehicle width direction. At this time, the portion on the left side of the rack shaft 16 in the state shown in FIG. 28 attempts to move backward along the surface of the support hole 51 of the left bearing 50 while rising upward (in the direction of the arrow Up). To do. The so-called “lifting amount” in which the rack shaft 16 rises increases as the bending force fb increases.

  As described above, the meshing configuration of the pinion 31K and the rack 32K is substantially the same configuration as when both the pinion 31K and the rack 32K are “quick teeth”. For this reason, the direction of the tooth trace of the pinion 31K matches the direction of the tooth trace of the rack 32K. Accordingly, when an external force in the upward direction, that is, an external force in the direction of the teeth of the rack 32K is applied to the rack 32K, the rack 32K is easily displaced in the direction of the “tooth lines” (tooth width direction). Thus, since the rack 32K is “immediately toothed”, the rack shaft 16 can be easily lifted.

  FIG. 30 shows the result of the rack shaft 16 retreating while rising. In FIG. 30, the contact point Qr where the back surface 16 a of the rack shaft 16 contacts the support holes 51, 51 of the bearings 50, 50 is positioned on the pinion orthogonal reference line Lc as the rack shaft 16 rises. It shows the state. Since the rear end of the rear surface 16a of the rack shaft 16 is in contact with the rear surface of the support hole 51 of the left bearing 50, the bearing 50 can sufficiently support the rack shaft 16, and the reaction force can be sufficiently and reliably ensured. I can take it.

  As described above, when a large reaction force is applied to the rack shaft 16, the bending force fb increases according to the magnitude of the reaction force. In response to this bending force fb, the rack shaft 16 rises rearward and upward while sliding along the surface of the support hole 51 of the bearing 50. That is, an indefinite support structure in which the support position at which the rack shaft 16 is supported by the bearing 50 (rack support portion 50) changes according to the magnitude of the reaction force applied to the rack shaft 16 is configured. The bearing 50 can firmly support the most appropriate portion of the back surface 16a of the rack shaft 16 according to the magnitude of the reaction force, for example, the contact point Qr. As a result, the rack shaft 16 is supported at three points: a meshing point between the pinion 31K and the rack 32K and a support point by the bearings 50 and 50. In addition, since the bearing 50 supports the back surface 16a of the rack shaft 16 at the most appropriate portion corresponding to the magnitude of the reaction force, the durability is high.

  By the way, when the rack 32K is a “helical tooth”, the teeth are formed obliquely with respect to the center line Pr of the rack shaft 16. For this reason, in any cross section orthogonal to the center line Pr of the rack shaft 16, there are teeth of the rack 32K in part. On the other hand, in the twelfth embodiment, since the rack 32K is “immediately toothed”, when the rack 32K is successively cross-sectioned along the center line Pr of the rack shaft 16, the tooth tip portion and the tooth bottom portion Is repeated. In other words, depending on the cross section, there is a part having only the tooth bottom. The cross-sectional secondary moment of the part having only the tooth bottom is smaller than the cross-sectional secondary moment of the other part. Accordingly, if the rack shaft 16 is viewed as a whole, the rack 32K is relatively easy to bend as compared to the case where the rack 32K is a “helical tooth”. Moreover, as described above, when an external force (including vibration) in the direction of the tooth trace of the rack 32K is applied to the rack 32K, the rack 32K is easily displaced in the direction of the “tooth trace”. Therefore, the back surface of the rack shaft 16 is reliably supported by the three points of the pinion 31K and the two rack support portions 50 and 50 so as to be slidable in the longitudinal direction of the shaft.

  Thus, even when a large reaction force is applied, the rack shaft 16 is sufficiently supported by the three points of the left and right bearings 50 and 50 and the pinion 31K.

  The displacement at the right end of the rack shaft 16 is in the reverse direction with respect to the displacement at the left end, and a description thereof will be omitted. Note that the rack shaft 16 is preferably configured as the rack shaft 16E of the sixth embodiment shown in FIGS. This is because when the rack shaft 16E approaches the pinion 31K side, at least one of the two rack approaching side convex portions 16Ec and 16Ed comes into contact with the bearings 50 and 50 first, so that the rack 32K is connected to the bearings 50 and 50, respectively. It is because it does not contact 50.

  Furthermore, since the overall length of the rack shaft 16 is short as described above, the pinion 31K can be positioned at the center of the vehicle width. On the other hand, the steering wheel 11 is biased to the left or right. That is, the pinion shaft 14 is inclined in the longitudinal direction of the rack shaft 16. The inclination direction of the pinion shaft 14 is opposite between the right-hand drive vehicle and the left-hand drive vehicle. However, since the rack 32K is “immediately toothed”, it can be shared by right-hand drive cars and left-hand drive cars. Management of the components of the steering device 10K is facilitated, and productivity is increased.

  According to the twelfth embodiment, the same operations and effects as those of the first embodiment are exhibited.

  A vehicle steering apparatus according to Embodiment 13 will be described with reference to FIGS. In the vehicle steering device 10L of the thirteenth embodiment, the urging portion 60 (rack guide mechanism 60) shown in FIG. 3 is changed to the urging portions 91 and 91 shown in FIGS. Since the other configuration is the same as the configuration shown in FIGS. 1 to 7, the description thereof is omitted.

  Specifically, the biasing portions 91 and 91 of the thirteenth embodiment bias the pinion 31 in a direction in which the pinion 31 meshes with the rack 32. The two urging portions 91, 91 are configured by strip plate-like “plate springs” provided between the housing 41 and the outer peripheral surfaces of the two bearings 43, 44.

  The plate springs 91, 91 are latched to the housing 41 by fitting both ends into the housing 41 while bending the plate springs 91, 91 like a bow in the plate thickness direction. The leaf springs 91 and 91 attached to the housing 41 are bent in an arc shape so as to individually enclose the outer peripheral surfaces of the two bearings 43 and 44. For this reason, the leaf springs 91 and 91 urge the pinion 31 in the direction of meshing with the rack 32 via the bearings 43 and 44 and the pinion shaft 14. For this reason, the favorable meshing state of the pinion 31 and the rack 32 can be maintained.

  As shown in FIG. 31, the resultant force F3 of the urging forces F1 and F2 of the leaf springs 91 and 91 is transmitted from the pinion 31 to the rack shaft 16 via the rack 32. At this time, as shown in FIG. 33, reaction forces F11 and F12 are generated in the two bearings 50 and 50 supporting the back surface 16a of the rack shaft 16, respectively. In this way, the back surface 16a of the rack shaft 16 is reliably supported by the three points of the pinion 31 and the two bearings 50 and 50 so as to be slidable in the longitudinal direction of the shaft. This rack shaft support configuration corresponds to a so-called “support configuration under a balancing condition in which a beam projects from both sides of two fulcrums and a concentrated load (the resultant force F3) acts on the longitudinal center of the beam”. In addition, the rack 32 itself is not supported by the bearings 50 and 50. For this reason, it is not necessary to provide a separate support member for supporting the rack shaft 16, and the support configuration can be simplified.

  In the thirteenth embodiment, the pinion 31 and the rack 32 have a “helical tooth” configuration. However, the rack 32 is an “immediate tooth” orthogonal to the rack shaft 16 and the pinion 31 is a “helical tooth”. The pinion shaft 14 can be tilted in the longitudinal direction of the rack shaft 16. It is also possible for both the pinion 31 and the rack 32 to be “quick teeth”.

  The vehicle rack-and-pinion steering devices 10 to 10L according to the present invention are suitable for mounting on a small vehicle having a small vehicle width.

  DESCRIPTION OF SYMBOLS 10,10A-10L ... Steering device for vehicles, 11 ... Steering wheel, 14 ... Pinion shaft, 15 ... Rack and pinion mechanism, 16 ... Rack shaft, 16a ... Back surface, 16Ea, 16Eb ... Rack opposite side convex part, 16Ec, 16Ed ... rack approaching side convex part, 16E ... hollow rack axis, 21 ... steering wheel, 31 ... pinion, 32 ... rack, 50 ... rack support part (cylindrical bearing), 51 ... support hole, 60, 60A-60J ... Biasing portion 61, 61A to 61C, 61G to 61K ... Rack guide, 61a ... Pressing surface, 61Ia ... Annular groove, 62 ... Compression coil spring, 64 ... Rack guide housing, 64a ... Support hole, 81G ... Oscillation Restriction part, 81Ga81Gb ... convex part, 81H ... swing restriction part, 81Ha ... filling layer, 82 ... O-ring, 91 ... urging part (leaf spring), P ... bearing center line, Pr ... rack shaft cross-sectional center (rack shaft center), Pp ... pinion center line, Lc ... pinion orthogonal reference line, Lp ... pinion parallel reference line, r1, r3, r4, r5 ... pressing The arcuate radius of the surface, r2 ... the arcuate radius of the back surface, θ ... the tilt angle.

Claims (15)

In a vehicle steering apparatus for transmitting a steering torque generated by steering a steering wheel from a steering wheel to a steering wheel via a rack and pinion mechanism,
A rack shaft on which a rack of the rack and pinion mechanism is formed;
Two rack support portions located on both sides in the longitudinal direction of the rack shaft with respect to the position of the pinion of the rack and pinion mechanism;
An urging portion positioned between the two rack support portions,
The two rack support parts are configured to support only the back surface of the rack shaft in a state where the rack shaft is positioned at a neutral position of steering so as to be slidable in the longitudinal direction of the shaft. Located close to each other,
The urging direction of the urging portion is set so as to be able to urge the rack shaft in at least a direction other than the rack. The biasing part is
A rack guide that slidably supports the back surface of the rack shaft at a position where the rack is formed;
A compression coil spring that urges the rack guide toward the back surface, and
The rack guide has a pressing surface for pressing the back surface,
The pressing surface is formed so as to be able to contact only one surface of the back surface with respect to a pinion orthogonal reference line orthogonal to the center line of the rack shaft and orthogonal to the center line of the pinion. The vehicle steering apparatus according to claim 1. At least the back surface of the rack shaft is formed in a substantially arc-shaped cross section,
The pressing surface is formed in a substantially arc-shaped cross section along the back surface,
The arcuate radius of the pressing surface is set larger than the arcuate radius of the back surface,
The vehicle steering apparatus according to claim 2, wherein the center of the pressing surface is offset in a tooth width direction of the rack with respect to a center line of the rack shaft. The biasing part is
A rack guide that slidably supports the back surface of the rack shaft at a position where the rack is formed;
A compression coil spring that urges the rack guide toward the back surface, and
A center line of the rack guide and a center line of the compression coil spring are inclined in the axial direction of the pinion with respect to a pinion orthogonal reference line orthogonal to the center line of the rack axis and orthogonal to the center line of the pinion. The vehicle steering apparatus according to claim 1, wherein: The two rack support portions are constituted by cylindrical bearings,
The center line of the rack shaft is offset in a direction away from the pinion with respect to the center line of the bearing and is offset along the center line of the pinion. The vehicle steering device according to claim 1. A straight line perpendicular to the center line of the rack axis and parallel to the center line of the pinion is defined as a pinion parallel reference line,
The two rack support portions are constituted by cylindrical bearings,
On the same circumference of the outer peripheral surface of the rack shaft, two rack-opposite convex portions that can be supported by the two bearings are formed,
5. The two rack opposite convex portions are located on the opposite side of the rack with respect to the pinion parallel reference line, and are located on both sides of the pinion orthogonal reference line. The steering apparatus for vehicles as described. Two rack approaching convex portions that can be supported by the two bearings are formed on the same circumference of the outer peripheral surface of the rack shaft,
7. The vehicle according to claim 6, wherein the two rack approaching side convex portions are located between the pinion parallel reference line and the rack and are located on both sides of the pinion orthogonal reference line. Steering device. The rack shaft is made of a hollow material,
The two rack opposite side convex portions and the two rack approaching side convex portions are portions formed by extruding from the inside of the hollow material toward the radially outer side. The vehicle steering device according to claim 7.   The vehicle steering apparatus according to claim 2, further comprising a swing restricting portion for restricting the rack guide from swinging around the pinion orthogonal reference line. The rack guide is a circular member centered on the pinion orthogonal reference line, and is housed in a rack guide housing.
This rack guide housing has a circular support hole capable of slidably supporting the rack guide along the pinion orthogonal reference line,
The rocking restricting portion is formed of at least two convex portions that are formed in a circumferential direction of the outer peripheral surface of the rack guide and are capable of contacting the inner peripheral surface of the support hole. Item 10. The vehicle steering device according to Item 9. The rack guide is a circular member centered on the pinion orthogonal reference line, and is housed in a rack guide housing.
This rack guide housing has a circular support hole capable of slidably supporting the rack guide along the pinion orthogonal reference line,
The swing restricting portion is configured by a filling layer having viscoelasticity such as liquid packing, which is filled in a gap between the outer peripheral surface of the rack guide and the inner peripheral surface of the support hole. The vehicle steering device according to claim 9. The rack guide is a circular member centered on the pinion orthogonal reference line, and an annular groove for mounting an O-ring is formed on the outer peripheral surface, and is housed in a rack guide housing.
This rack guide housing has a circular support hole capable of slidably supporting the rack guide along the pinion orthogonal reference line,
The swing restricting portion is configured by an O-ring attached to the annular groove,
The vehicle steering apparatus according to claim 9, wherein an outer peripheral surface of the O-ring is in contact with an inner peripheral surface of the support hole over the entire periphery.   The vehicle steering apparatus according to claim 12, wherein the center of the annular groove is offset with respect to the center line of the rack guide.   The vehicle steering apparatus according to claim 1, wherein the biasing portion biases the pinion in a direction in which the pinion meshes with the rack.   The vehicle steering apparatus according to any one of claims 1 to 14, wherein the rack is an immediate tooth having a tooth line perpendicular to the rack shaft.

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