JP2008132870A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a center take-off type steering system. <P>SOLUTION: A steering system 1 includes an attachment bracket 39 to attach inner ends 28b of a pair of tie rods 28, which are taken out of a center position 9a in the lateral direction of a vehicle body 9, to a rack shaft 14. The attachment bracket 39 includes a base 39a and a supporting part 39b. Fixing screws 41 are inserted through a pair of screw insertion holes 39c on the base 39a, thereby, the attachment bracket 39 is secured to the rack shaft 14. The base 39a extends parallel to the direction X2 of the rack shaft 14. The supporting part 39b rises from one end 39f of the base 39a with respect to the axial direction X1 of the rack shaft 14 and respectively supports the inner ends 28b of the pair of tie rods 28 through hemispheric bearings 40. The base 39a and the supporting part 39b form an L-shaped structure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a steering device.

  As the steering device, there is a so-called center take-off type steering device. In this type of steering device, the tie rod connected to the wheel is taken out from the center position in the left-right direction of the vehicle body. For example, the steering mechanism includes a rack shaft and a long cylindrical rack housing that receives the rack shaft. A long hole is formed in an intermediate portion of the rack housing in the longitudinal direction. Through this long hole, the rack shaft and the tie rod are connected to each other via a mounting bracket (see, for example, Patent Documents 1 and 2).

  In Patent Document 1, the mounting bracket has a rectangular parallelepiped shape, and the mounting bracket is fixed to the rack shaft with bolts so that the longitudinal direction thereof is parallel to the rack shaft. The bolt passes through the mounting bracket at a right angle to the longitudinal direction of the mounting bracket. A tie rod is connected to the end face of the mounting bracket in the longitudinal direction via a spherical bearing.

In Patent Document 2, the mounting bracket has a T-shape, and includes a base fixed to the rack shaft by a pair of bolts and a support stay rising from the center of the base. A tie rod is connected to the support stay via a spherical bearing. Moreover, the bolt is arrange | positioned on both sides on both sides of the support stay.
Japanese Patent Laid-Open No. 11-321694 JP 2001-151140 A

  However, in Patent Document 1, with respect to the axial direction of the rack shaft, since the bolt is disposed between the pair of spherical bearings, the distance between the spherical bearings becomes long, and the tie rod becomes short. As a result, steering stability and high-speed stability of the vehicle tend to decrease.

  In Patent Document 2, since the support stay is interposed between the pair of fixing bolts with respect to the axial direction of the rack shaft, the interval between the fixing bolts is increased, resulting in an increase in the size of the rack shaft and consequently the steering device.

  Therefore, an object of the present invention is to provide a steering device that is excellent in steering stability and suitable for downsizing.

  The present invention converts the rotation of the pinion (13) rotating in conjunction with the steering member (3) into a linear displacement of the rack shaft (14) extending in the left-right direction (X) of the vehicle body (9). In the center take-off type steering device in which a pair of tie rods (28) for receiving and turning each of the pair of wheels (2) are taken out from the center position (9a) in the left-right direction of the vehicle body, A mounting bracket (39) for attaching the end (28b) to the rack shaft is provided, and this mounting bracket is a screw insertion hole (39c) through which a fixing screw (41) for fixing the mounting bracket to the rack shaft is inserted. ) Having a base (39a) and one end (39f) of the base, and supporting the ends of a pair of tie rods via spherical bearings (40), respectively. That is characterized in that it comprises a support and (39 b).

  According to the present invention, for example, when the base is fixed by two fixing screws arranged in the axial direction of the rack shaft, the fixing screw can be arranged without being regulated by the support portion. As a result of being shortened, the interval between the screw holes into which the fixing screws are screwed in the rack shaft can be shortened, and consequently the rack shaft can be shortened. Therefore, the steering device can be reduced in size. In addition, with respect to the axial direction of the rack shaft, it is not necessary to secure a space for passing the fixing screw between the spherical bearings, so that it is possible to shorten the interval between the spherical bearings and thus to increase the length of the tie rod. Become. As a result, the toe change at the time of the tire stroke can be reduced, and the steering stability and the high-speed stability of the vehicle can be improved.

  In the present invention, the base and the support portion may be connected to each other to form an L shape. In this case, since the shape of the mounting bracket can be simplified, the manufacturing cost can be reduced.

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

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Although the present embodiment will be described based on the case where the steering device is an electric power steering device, the present invention is not limited thereto, and for example, a steering device for manual steering may be used. FIG. 1 is a schematic diagram showing a schematic configuration of a steering apparatus according to an embodiment of the present invention.

  Referring to FIG. 1, a steering device 1 steers a wheel 2 by a steering shaft 4 that transmits a steering torque applied to a steering wheel 3 as a steering member to steer the wheel 2, and the steering torque from the steering shaft 4. For example, a steering mechanism 5 comprising a rack and pinion mechanism, and an intermediate shaft 6 provided between the steering shaft 4 and the steering mechanism 5 as a shaft coupling for transmitting rotation therebetween.

  The steering shaft 4 is inserted into the steering column 7 and is rotatably supported by the steering column 7. The steering column 7 is supported on the vehicle body 9 via a bracket 8. A steering wheel 3 is connected to one end of the steering shaft 4 and is rotatably supported. An intermediate shaft 6 is connected to the other end of the steering shaft 4.

  The intermediate shaft 6 includes a power transmission shaft 10, a universal joint 11 provided at one end of the intermediate shaft 6, and a universal joint 12 provided at the other end of the intermediate shaft 6.

  The steering mechanism 5 supports a pinion 13 as an input shaft, a rack shaft 14 as a steered shaft extending in the left-right direction X of the automobile (a direction orthogonal to the straight traveling direction), the pinion 13 and the rack shaft 14. And a rack housing 15. The pinion teeth 13a of the pinion 13 and the rack teeth 14a of the rack shaft 14 mesh with each other.

  The pinion 13 is rotatably supported by the rack housing 15. The rack shaft 14 is supported by the rack housing 15 so as to be linearly reciprocable. The rack housing 15 is fixed to the vehicle body 9. The rack shaft 14 is connected to the corresponding wheel 2 via a tie rod 28 and a knuckle arm (not shown) which will be described later.

  When the steering wheel 3 is steered, the steering torque is transmitted to the steering mechanism 5 via the steering shaft 4 and the intermediate shaft 6, and the rotation is caused by the pinion teeth 13 a and the rack teeth 14 a along the left-right direction X of the automobile. Is converted into a linear motion of the rack shaft 14. Thereby, the wheel 2 can be steered.

  The steering device 1 can obtain a steering assist force according to the steering torque. That is, the steering device 1 includes a torque sensor 16 that detects steering torque, an ECU (Electronic Control Unit) 17 as a control unit, an electric motor 18 for assisting steering, and a speed reducer 19 as a gear device. And have. In the present embodiment, the electric motor 18 and the speed reducer 19 are provided in association with the steering column 7.

  The steering column 7 has a column tube 20 and a housing 21. A housing 21 accommodates and supports the torque sensor 16, supports the electric motor 18, and constitutes a part of the speed reducer 19.

  The steering shaft 4 includes an input shaft 22, an output shaft 23, and a torsion bar 24 as a lower portion in the axial direction, and a connecting shaft 25 as an upper portion in the axial direction. The input shaft 22 and the output shaft 23 are connected to each other on the same axis via a torsion bar 24. The input shaft 22 is connected to the steering wheel 3 via the connecting shaft 25. The output shaft 23 is connected to the intermediate shaft 6. When steering torque is input to the input shaft 22, the torsion bar 24 is elastically torsionally deformed, whereby the input shaft 22 and the output shaft 23 are relatively rotated.

  The torque sensor 16 is provided in association with the torsion bar 24 of the steering shaft 4 and detects torque based on the amount of relative rotational displacement between the input shaft 22 and the output shaft 23 via the torsion bar 24. The torque detection result is given to the ECU 17.

  The ECU 17 controls the electric motor 18 based on the above torque detection result, a vehicle speed detection result given from a vehicle speed sensor (not shown), and the like.

  When the steering wheel 3 is operated, the steering torque is detected by the torque sensor 16, and the electric motor 18 generates a steering assist force according to the torque detection result and the vehicle speed detection result. The steering assist force is transmitted to the steering mechanism 5 via the speed reducer 19. At the same time, the movement of the steering wheel 3 is also transmitted to the steering mechanism 5. As a result, the steering wheel 2 is steered and the steering is assisted.

  The steering device 1 of the present embodiment is configured as a center take-off type steering device. That is, the pair of tie rods 28 is led out from the center position 9 a in the left-right direction X of the vehicle body 9.

  The steering mechanism 5 supports the pinion 13, the rack shaft 14, the rack housing 15, the cylindrical rack bush 26 that supports the axial end of the rack shaft 14, and the central portion of the rack shaft 14 in the axial direction. A supporting device 27, a pair of tie rods 28, a connecting portion 29 for connecting the pair of tie rods 28 and the rack shaft 14 to each other, and a dust cover 30.

  The rack bush 26 is supported at one end of the rack housing 15 with respect to the axial direction X1 of the rack shaft 14. The rack bush 26 has a cylindrical shape. The rack shaft 14 is inserted through the rack bush 26. The rack bush 26 supports the rack shaft 14 so as to be relatively slidable in the axial direction X1.

  The support device 27 supports the rack shaft 14 so as to be movable in the axial direction X1 while biasing the rack shaft 14 in a predetermined biasing direction toward the pinion 13, that is, in a direction orthogonal to the axial direction X1. . The support device 27 is disposed at the same position as the pinion shaft 13 in the intermediate portion of the rack housing 15 with respect to the axial direction X1. With respect to the direction orthogonal to the axial direction X1, the support device 27 and the pinion 13 are disposed on opposite sides of the rack shaft 14 therebetween.

  A pair of tie rods 28 are connected to a portion of the rack shaft 14 between the rack bush 26 and the support device 27 with respect to the axial direction X1 via a connecting portion 29.

  Each tie rod 28 is a rod-like connecting member that receives the linear displacement of the rack shaft 14 and steers the wheel 2 along with this, and connects the rack shaft 14 and the corresponding wheel 2 to each other. An outer end 28 a as an outer end portion of each tie rod 28 is connected to the wheel 2. An inner end 28b as an inner end portion of each tie rod 28 is disposed at a substantially central position of the vehicle body 9 in the left-right direction X of the vehicle body 9, and is connected to an intermediate portion of the rack shaft 14 in the axial direction X1 of the rack shaft 14. Has been.

  FIG. 2 is a partial cross-sectional view of a main part of the steering mechanism 5 of FIG. FIG. 3 is a partial cross-sectional view taken along the line III-III of FIG. FIG. 4 is a perspective view of the main part of the steering mechanism 5, schematically showing the peripheral part.

  Referring to FIGS. 1 and 2, the rack shaft 14 has a pair of attachment portions 31 for attaching the connecting portion 29 to an intermediate portion in the axial direction X1. Each attachment portion 31 has a recess 31a that receives a spacer 44 (described later) of the connecting portion 29 in a positioned state, and a screw hole 31c formed in the bottom 31b of the recess 31a. A fixing screw 41 (to be described later) of the connecting portion 29 is screwed into the screw hole 31c.

  The rack housing 15 supports the rack shaft 14 slidably along the axial direction X1 of the rack shaft 14. The rack housing 15 includes a gear housing 32 in which the pinion 13 is accommodated, and a long cylindrical tube portion 33 that is connected to the gear housing 32. The gear housing 32 supports the pinion 13 and the support device 27. The longitudinal direction of the cylindrical portion 33 (also referred to as the longitudinal direction of the rack housing 15) is arranged in parallel with the axial direction X1 of the rack shaft 14. One end of the cylindrical portion 33 is fixed to the gear housing 32. The cylindrical portion 33 accommodates the rack shaft 14 therein, supports the rack bush 26 at the other end, and supports the rack shaft 14 via the rack bush 26. An intermediate portion of the cylindrical portion 33 in the longitudinal direction of the rack housing 15 has a long hole 34.

  The long hole 34 extends in the longitudinal direction of the rack housing 15. The connecting portion 29 is passed through the long hole 34. A long hole 34 is formed in accordance with the movement range of the connecting portion 29 so that the connecting portion 29 can move as the rack shaft 14 is displaced in the axial direction X1.

  The dust cover 30 has a cylindrical shape extending in one direction, and is formed to be extendable in a direction (longitudinal direction) in which the dust cover 30 extends by a rubber member or a synthetic resin member as an elastic member. The longitudinal direction of the dust cover 30 is arranged in parallel to the longitudinal direction of the rack housing 15. The dust cover 30 covers the long hole 34 of the rack housing 15.

  Both end portions 35 of the dust cover 30 in the longitudinal direction of the dust cover 30 are fixed to the cylindrical portion 33 of the rack housing 15. The central portion 36 of the dust cover 30 in the longitudinal direction of the dust cover 30 is adapted to move along with the connecting portion 29 and has a pair of holes 36 c penetrating into and out of the dust cover 30. The hole 36 c is provided to connect the tie rod 28 and the rack shaft 14 to each other, and is penetrated by a slider 38 and a fixing screw 41 described later of the connecting portion 29.

  Referring to FIGS. 2 and 3, the connecting portion 29 is moved integrally with the rack shaft 14 and slides on the inner periphery of the long hole 34 of the rack housing 15, and a pair of tie rods 28 are attached to the slider 38. A mounting bracket 39 for mounting, a spherical bearing 40 as a pair of joints that swingably connect the mounting bracket 39 and the pair of tie rods 28, a mounting bracket 39 and a slider 38 are fixed to the rack shaft 14. A plurality of, for example, two fixing screws 41 as fixing members. The inner end 28 b of the tie rod 28 is connected to the rack shaft 14 via a spherical bearing 40, a mounting bracket 39, and a slider 38.

  The spherical bearing 40 includes a ball and a receiving member having a concave curved shape for receiving the ball. The ball forms a partial spherical surface and is fixed to the inner end 28 b of the tie rod 28. The center of the partial spherical surface of the ball is the center 40 c of the spherical bearing 40. The tie rod 28 is swingable around the center 40c. Further, the receiving member forms a partial spherical surface. The receiving member is provided with a male screw for mounting to the mounting bracket 39.

  Referring to FIGS. 2 and 4, the mounting bracket 39 is provided for mounting the inner end 28 b of each tie rod 28 to the rack shaft 14. The mounting bracket 39 has a base 39a as a base portion facing the slider 38, and a support portion 39b as an arm portion protruding from the base 39a. The base 39a and the support portion 39b are integrally formed of a single member and have an L shape.

  The base 39a is a long plate-like member and extends in a direction X2 parallel to the axial direction X1 of the rack shaft 14. The direction in which the base 39a extends is only required to be substantially parallel to the axial direction X1 of the rack shaft 14, and is a minute angle with respect to the direction X2 parallel to the axial direction X1, for example, an angle within a range of 0 degrees to 10 degrees. May extend.

  The base 39a has a pair of screw insertion holes 39c penetrating the base 39a. The pair of screw insertion holes 39c is adjacent to the axial direction X1. The fixing screw 41 is inserted through the screw insertion hole 39c. Further, the base 39 a has a facing portion 39 d that faces the dust cover 30. At least a part of the facing portion 39 d is in contact with the dust cover 30.

  The support portion 39b rises from one end 39f of the base 39a with respect to the direction X2 parallel to the axial direction X1 of the rack shaft 14, and extends in a direction away from the rack shaft 14 in a direction perpendicular to the axial direction X1. The above-mentioned one end 39f is, for example, an end portion relatively far from the pinion 13. A pair of spherical bearings 40 are connected to the support portions 39b, and the inner ends 28b of the pair of tie rods 28 are supported via the spherical bearings 40, respectively. In other words, the support portion 39b has a screw hole extending in the axial direction X1 of the rack shaft 14. The male screw of the spherical bearing 40 is screwed into the screw hole.

  The fixing screw 41 passes through the mounting bracket 39 and the slider 38 and is fixed to the rack shaft 14. The fixing screw 41 is specifically a bolt, and has a head portion 41a and a shaft portion 41b on which a male screw is formed. In this embodiment, the center axis 41c of the fixing screw 41 intersects the center axis 14c of the rack shaft 14 perpendicularly. However, the center axis 41c of the fixing screw 41 intersects the center axis 14c of the rack shaft 14 obliquely, or the rack shaft 14 It is also conceivable that they are arranged in parallel to the direction intersecting with the central axis 14c. The male screw of the shaft portion 41 b of the fixing screw 41 is screwed into the screw hole 31 c of the mounting portion 31 of the rack shaft 14. A mounting bracket 39 and a slider 38 are sandwiched between the head 41 a of the fixing screw 41 and the bottom 31 b of the recess 31 a of the mounting portion 31 of the rack shaft 14.

  2 and 3, the slider 38 is fixed to the mounting portion 31 of the rack shaft 14 so that the slider 38 can move integrally with the rack shaft 14. The slider 38 is interposed between the mounting bracket 39 and the rack shaft 14, and connects the both 14 and 39. The slider 38 holds the central portion 36 of the dust cover 30 so that it can move integrally.

  The slider 38 includes a first connecting portion 38 a that is fixedly connected to the rack shaft 14, a second connecting portion 38 b that is fixedly connected to the mounting bracket 39, and an inner periphery of the long hole 34 of the rack housing 15. A sliding contact portion 38c that is slidably fitted to the mounting bracket 39, a holding portion 38d that faces the mounting bracket 39 and holds the dust cover 30 in a sandwiched state, and an insertion hole 38e through which the fixing screw 41 is inserted. ing.

  The slider 38 includes a main body 42 and two convex portions 43. The two convex portions 43 are formed in the same manner. The main body portion 42 is disposed closer to the rack shaft 14 than the holding portion 38d. The main body 42 has the first connecting portion 38a, the sliding contact portion 38c, and the holding portion 38d. The convex portion 43 is constituted by a portion of the slider 38 that is on the tip side of the holding portion 38d, and protrudes from the main portion 42 in a direction that intersects the axial direction X1 of the rack shaft 14 at a right angle. The convex part 43 has the 2nd connection part 38b. Further, the insertion hole 38 e passes through the main body portion 42 and the convex portion 43.

  Specifically, the slider 38 includes a pair of cylindrical spacers 44 and a connecting member 45 that connects the pair of spacers 44 to each other. The pair of spacers 44 and the connecting member 45 are formed separately from each other, and constitute a slider 38 by being combined.

  Referring to FIG. 4, the steering device 1 of the present embodiment converts the rotation of the pinion 13 that rotates in conjunction with the steering wheel 3 as a steering member into a linear displacement of the rack shaft 14 that extends in the left-right direction X of the vehicle body 9. The center take-off type steering device is configured to take out the pair of tie rods 28 for turning the pair of wheels 2 in response to the linear displacement from the center position 9a in the left-right direction X of the vehicle body 9. The steering device 1 includes an attachment bracket 39 for attaching an inner end 28 b as an end portion of the pair of tie rods 28 to the rack shaft 14. The mounting bracket 39 includes (1) a base 39a having a screw insertion hole 39c through which a fixing screw 41 for fixing the mounting bracket 39 to the rack shaft 14 is inserted, and (2) rising from one end 39f of the base 39a. In addition, support portions 39b for supporting the inner ends 28b of the pair of tie rods 28 via the spherical bearings 40 are included.

  According to the present embodiment, since the support portion 39b is disposed at the one end 39f of the base 39a, the fixing screw 41 can be disposed without being restricted by the support portion 39b, so that the two fixings are performed with respect to the axial direction X1 of the rack shaft 14. As a result of shortening the interval between the screws 41, the interval between the screw holes 31c into which the fixing screws 41 are screwed in the rack shaft 14 can be shortened. As a result, the rack shaft 14 can be shortened. Therefore, the steering device 1 can be reduced in size.

  Since the rack shaft 14 can be shortened as described above, the interval between the rack housings 15 for supporting the rack shaft 14 with respect to the axial direction X1 of the rack shaft 14, that is, the rack bush 26 and the support device 27. The interval can be shortened. Further, since the interval between the fixing screws 41 can be shortened, the long hole 34 of the rack housing 15 can be shortened, and as a result, the rigidity of the rack housing 15 can be increased and the rack housing 15 can be hardly damaged.

  Further, since it is not necessary to secure a space for passing the fixing screw 41 between the spherical bearings 40 with respect to the axial direction X1 of the rack shaft 14, it is possible to shorten the interval between the spherical bearings 40, and thus the tie rod 28. It can be made longer. When the tie rod 28 is lengthened, the toe change at the time of the tire stroke, that is, when the wheel 2 moves in the vertical direction can be reduced. As a result, steering stability and high-speed stability of the vehicle can be improved.

  The base 39a and the support portion 39b are connected to each other to form an L shape. In this case, since the shape of the mounting bracket 39 can be simplified, the manufacturing cost can be reduced.

  Moreover, the following modifications can be considered about this embodiment. In the following description, differences from the above-described embodiment will be mainly described, and the same components are denoted by the same reference numerals and description thereof is omitted.

  For example, FIG. 5 is a perspective view of a mounting bracket 39 as a main part of the steering apparatus according to the second embodiment of the present invention, and schematically shows a peripheral portion. Referring to FIG. 5, the mounting bracket 39 is fixed to the rack shaft 14 by a single fixing screw 41. The base 39a of the mounting bracket 39 has a single screw insertion hole 39c. The rack shaft 14 has a single mounting portion 31.

  In the present embodiment, with respect to the axial direction X1 of the rack shaft 14, the rack shaft 14 can be shortened because the screw shaft 31c into which the fixing screw 41 is screwed in the rack shaft 14 is only required in one place. Therefore, the steering device 1 can be reduced in size. Further, as in the first embodiment, with respect to the axial direction X1 of the rack shaft 14, the interval between the portions of the rack housing 15 for supporting the rack shaft 14 can be shortened. 34 can be shortened, the rigidity of the rack housing 15 can be increased, and the rack housing 15 can be hardly damaged. It becomes possible to lengthen the pair of tie rods 28, and toe change at the time of tire stroke can be reduced. As a result, steering stability and high speed stability of the vehicle can be improved.

  Further, in each of the above-described embodiments, it may be considered that the support portion 39b rises from the end portion of the base 39a that is relatively closer to the pinion 13 in the direction X2.

  Moreover, although the above-described steering device 1 uses an electric motor as a drive source for obtaining a steering assist force, a hydraulic power cylinder as a hydraulic actuator may be used. Further, a drive source for obtaining a steering assist force may be provided in the rack housing 15 in addition to the steering column 7. In addition, various design changes can be made within the scope of matters described in the claims.

It is a mimetic diagram showing a schematic structure of a steering device of one embodiment of the present invention. FIG. 4 is a partial cross-sectional view of a main part of the steering mechanism of FIG. 1, showing a II-II cross section of FIG. 3. FIG. 3 is a partial cross-sectional view taken along the line III-III in FIG. 2. It is a perspective view of the principal part of the steering mechanism of FIG. 1, and one part is shown typically. It is a perspective view of the principal part of the steering device of the 2nd Embodiment of this invention, and has shown the peripheral part typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Steering device, 2 ... Wheel, 3 ... Steering wheel (steering member), 9 ... Vehicle body, 9a ... Center position, 13 ... Pinion, 14 ... Rack shaft, 28 ... Tie rod, 28b ... Inner end (end part of tie rod) , 39 ... mounting bracket, 39a ... base, 39b ... support portion, 39c ... screw insertion hole, 39f ... one end, 40 ... spherical bearing, 41 ... fixing screw, X ... left and right direction of vehicle body, X1 ... axial direction of rack shaft

Claims (2)

The rotation of the pinion that rotates in conjunction with the steering member is converted into a linear displacement of the rack shaft that extends in the left-right direction of the vehicle body, and a pair of tie rods for turning the pair of wheels in response to this linear displacement are converted to the left and right sides of the vehicle body. In the center take-off type steering device that is taken out from the center position in the direction,
A mounting bracket for mounting the ends of the pair of tie rods to the rack shaft;
The mounting bracket includes a base having a screw insertion hole through which a fixing screw for fixing the mounting bracket to the rack shaft is inserted, and ends of the pair of tie rods via spherical bearings. A steering device comprising: a supporting portion that supports the steering device.   The steering apparatus according to claim 1, wherein the base and the support portion are connected to each other to form an L shape.

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