JPH0640540Y2 - Rack and pinion gearing - Google Patents

Description

The present invention relates to a rack and pinion gear device, for example, a rack and pinion gear device provided in a steering system of an automobile.

(Prior Art) Generally, a rack-and-pinion gear device has a simple structure in which a pinion and a rack are meshed with each other to change the direction of motion. For example, a steering force that rotates a steering wheel causes a steering wheel to move to a steering angle. It is provided as a steering gear in a steering system of an automobile that provides In such a rack and pinion gear device, the rotation of the pinion based on the rotation of the steering wheel is reliably transmitted to the rack to suppress steering loss, and unnecessary vibration and impact from the wheels input to the rack are damped. Therefore, it is necessary to maintain an appropriate steering force.

A conventional rack-and-pinion gear device of this type is disclosed in, for example, Japanese Patent Application Laid-Open No. 55-24262, and is shown in FIGS.

In FIG. 3, 1 is a pinion, and the pinion 1 is rotatably supported by the housing 2. A rack 3 is provided below the pinion 1 so as to penetrate the housing 2, and the pinion 1 and the rack 3 are formed with teeth having a predetermined shape that mesh with each other. The pinion 1 is connected to the steering wheel S, rotates based on the rotation of the steering wheel S, and moves the rack 3 in the axial direction. The rack 3 is connected to the steered wheels W via tie rods L at both ends, and the steering wheel W is provided with a steering angle by the axial movement of the rack 3.

As shown in FIG. 4, the rack 3 is formed in a wedge shape having a rear surface 3a and sliding surfaces 3b and 3c on the side opposite to the pinion 1, and the rear surface 3a is provided with a roller support 4 and a leaf spring 5 therebetween. It is elastically supported by the cover 2a of the housing 2. The roller support 4 rolls into contact with the rack 3 to reduce the movement resistance of the rack 3 and reduce the steering force. The leaf spring 5 urges the rack 3 to the pinion 1 via the roller support 4 and suppresses backlash between the pinion 1 and the rack 3. In addition, the leaf spring 5 receives a shock from the road surface or the like on the steered wheels W while traveling and the pinion 1
When the meshing pressure of the rack 3 reaches a predetermined value, it is compressed by the repulsive force acting in the direction perpendicular to the axis of the pinion 1 and the rack 3 due to the pressure angle.
That is, the rack 3 can be displaced in a direction in which the engagement depth between the pinion 1 and the rack 3 becomes shallow. When the rack 3 is displaced by a predetermined amount, the rack 3 is slidably contacting the slidable contact portions 6a and 6b of the slidable contact member 6 supported by the housing 2, and the slidable contact portions 6a and 6b are not easily inserted. By increasing the sliding resistance between the members 6, the impact force or the like from the steered wheels W input to the rack 3 is attenuated to reduce the impact transmitted to the steering wheel S, and at the time of impact input, the rack 3 Sliding surfaces 3b, 3c of the sliding contact member 6 of the sliding contact member 6
By being supported by a and 6b, the back surface 3a of the rack 3 and the roller support 4 are prevented from being damaged due to bottom abutment. Therefore, the sliding surfaces 3b, 3c of the rack 3 and the sliding contact portions 6a, 6b of the sliding contact member 6 are separated by a predetermined gap g so as not to increase the sliding resistance during normal traveling.

FIG. 5 shows another example described in the publication.
In FIG. 5, the rack 3 is supported by the housing 2 via a rack support 7 having a centering function, and the rack support 7 rolls on the sliding surfaces 3b, 3c of the rack 3 and rolls 8, 9 And a pair of sliding contact portions 10a, 10b arranged on both sides of the rollers 8, 9 in the rack 3 axial direction. Laura 8,9
Is rotatably supported by the support member 10 via roller shafts 11 and 12 that are cantilevered by the support member 10, and the sliding surface 3 of the rack 3 is supported.
The rack 3 is biased so as to make rolling contact with b and 3c.
The sliding contact portions 10a, 10b are formed on the support member 10 and are adapted to engage with the sliding surfaces 3b, 3c of the rack 3 to give sliding resistance, like the sliding contact portions 6a, 6b in the above-mentioned example. There is. Further, when the rack 3 is displaced by the above-mentioned repulsive force in the direction in which the meshing depth becomes shallow, the rack 3 bends the roller shafts 11 and 12 via the rollers 8 and 9. Further, the rack support 7 is adjusted in position by the adjusting member 13 screwed to the housing 2, the sliding contact portions 10a, 10b of the supporting member 10 are separated from the rack 3 by a predetermined gap, and the roller shafts 11, 12 are slightly separated. The rack 3 is biased by the pinion 1 by bending at a bending angle. Reference numeral 14 is a set screw for fixing the fixed end sides of the roller shafts 11 and 12 to the support member 10.

(Problems to be Solved by the Invention) However, in the former rack-and-pinion gear device shown in FIGS. 3 and 4, since the rack 3 and the sliding contact member 6 are separated by a gap g, If the pinion 1 has a spiral tooth profile with a steep angle and the rack 3 does not have a tooth profile orthogonal to the axial direction, the rack 3 is displaced in the axial direction of the pinion 1 by the lateral force acting on the rack 3 during steering. There was a problem that steering loss occurs at the beginning of turning. Further, in the latter rack-and-pinion gear device shown in FIG. 5, although the rack support 7 has an aligning function, the above-mentioned problems can be solved.
When an impact load or the like from the steering wheel W is input to the rack 3, the roller shaft 1 cantilevered by the support member 10
Since it was configured to displace while bending 1 and 12, the shaft length of the roller shafts 11 and 12 could not be shortened, and the roller shaft 1
The supporting member 10 that supports the members 1 and 12 has a complicated shape, and the supporting member 10 needs to have strength to withstand an impact load. Therefore, there is a problem that the rack support 7 becomes large and complicated and the manufacturing cost of the rack and pinion gear device increases.

Therefore, an object of the present invention is to provide a low-cost rack-and-pinion gear device that has no steering loss, is small in size, and has a simple structure.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention has a pinion rotatably supported by a support, meshes with the pinion, and moves in the axial direction by the rotation of the pinion. A rack-and-pinion gear device including a rack displaceable in a direction in which the meshing depth becomes shallower as the meshing pressure increases, and a rolling support portion supported by a support so as to support the rack by rolling contact with the rack. In, the rolling support portion,
A support member supported by a support body, a roller shaft supported by the support member so as to be substantially orthogonal to the rack, and a roller shaft rotatably and movably in the axial direction, and moved in the axial direction by displacement of the rack. So as to sandwich the rack, at least a pair of rollers, an elastic member that applies an urging force to the rollers so that the rollers make rolling contact with the back side of the rack, and after a predetermined amount of movement of the rollers, slide them into contact with the back side of the rack. And a sliding contact member that supports the sliding contact member.

(Operation) In the present invention, the pair of rollers arranged with the rack sandwiched therebetween is biased to the rack by the elastic member, and the rollers are moved in the axial direction of the roller shaft by the displacement of the rack according to the meshing pressure between the pinion and the rack. Be moved.

Therefore, when the meshing pressure is temporarily increased by the impact load or the like input from the steering wheel to the rack, the roller moves on the roller shaft while bending the elastic member, and after the predetermined amount of movement, The rack is supported by the sliding contact member.

(Example) Hereinafter, the present invention will be described with reference to the drawings.

1 and 2 are views showing an embodiment of a rack and pinion gear device according to the present invention, which is an example in which the present invention is applied to a steering gear of an automobile.

First, the configuration will be described. In FIG. 1, reference numeral 21 is a pinion, and the pinion 21 is rotatably supported by a housing 22 (support) having a bearing 22a and a cover 22b.
A rack 23 is provided below the pinion 21 so as to penetrate the housing 22 (support) so as to intersect with the pinion 21 at a predetermined angle. The pinion 21 and the rack 23 are formed with teeth of a predetermined shape that mesh with each other. ing. The pinion 21 is connected to a steering wheel (not shown) outside the housing 22 (support), and the pinion 21 moves the rack 23 in the axial direction while rotating in accordance with the rotation of the steering wheel. The rack 23 is connected to steering wheels (not shown) at both ends, and the steering wheel is given a steering angle as the rack 23 moves in the axial direction.

A rolling support portion 23 is provided on the opposite side of the rack 23 from the pinion 21, and the rolling support portion 24 includes a support member 25 and a roller shaft.
It has a roller 26 and an elastic member 28. Support member
25 is supported by a cover 22b of the housing 22 (support) via a coil spring 29, and a pair of roller shafts 26 are fixed to the support member 25 so as to be orthogonal to the rack 23. A roller 27 is supported on each roller shaft 26 so as to be rotatable and axially movable, and at least one pair of rollers 27 are provided with the rack 23 interposed therebetween. The rollers 27 are biased by an elastic member 28 such as a disc spring so that the rollers 27 come close to each other and come into rolling contact with the curved back surface 23a of the rack 23. The rack 23 is aligned while being urged by the pinion 21. The elastic member 28 and the coil spring 29 are installed in the rack 23.
When the meshing pressure between the pinion 21 and the rack 23 reaches a predetermined value due to the impact from the steering wheel, etc., while backlash is suppressed between the pinion 21 and the rack 23 by urging the , And is compressed by the repulsive force acting in the direction perpendicular to the axis of the pinion 21 and the rack 23 due to the pressure angle. That is, the repulsive force allows the rack 23 to be displaced in the direction in which the engagement depth between the pinion 21 and the rack 23 becomes shallow, and the rollers 27 can move axially away from each other.

On the other hand, the support member 25 of the rolling support portion 24 is formed with a concave sliding contact portion 25a facing the curved back surface 23a of the rack 23, and the supporting member 25 also functions as a sliding contact member. When the rollers 27 are separated from each other by a predetermined amount due to the displacement of the rack 23, the roller 23 presses the curved back surface 23a of the rack 23. Then, the impact or the like input from the steering wheel to the rack 23 is attenuated while being attenuated by the sliding resistance of the rack 23 and the support member 25 so that the support member 25 receives the pressure.

Incidentally, 30 is a washer, and the washer 30 is interposed between the support member 25 and the elastic member 28.

Next, the operation will be described.

When the steering wheel is steered, the pinion 21 rotates according to the rotation of the steering wheel, the rack 23 is moved in the axial direction, and the steering wheel is given a steering angle. At this time, the rack 23 is supported by the rolling support portion 24, and the rack 23 can be moved only by the rolling resistance of the rollers 27, so that the steering force is reduced. Further, since the rack 23 does not move to the side during steering due to the centering function of the roller 27, and the rack 23 is biased to the pinion 21 by the elastic member 28 and the coil spring 29, the gap between the pinion 21 and the rack 23 is reduced. Backlash does not occur. Therefore, the rotation of the steering wheel can be immediately transmitted from the pinion 21 to the rack 23, and there is no steering loss.

Now, for example, if an impact is applied to the steering wheel and a large impact load is input in the axial direction of the rack 23, a repulsive force in the direction perpendicular to the axis due to the pressure angle acts at the meshing portion of the pinion 21 and the rack 23, 23 is displaced in the direction in which the engagement depth becomes shallower. At this time, the rollers 27, which are in rolling contact with the curved back surface 23a of the rack 23, move in the axial direction while compressing the elastic member 28 and separate from each other. Next, the curved back surface 23a of the rack 23 is pressed against the sliding contact portion 25a of the support member 25, and the rack 23
The impact load input to is damped by the sliding resistance of the rack 23 and the support member 25. Therefore, a large impact from the steered wheels is effectively mitigated, kicking back to the steering wheel is suppressed, and the steering feeling is not impaired. Also,
By receiving the shock load at the sliding contact portion 25a, the roller 27 does not bottom out and the curved back surface 23a of the rack 23 and the contact portion of the roller 27 are not damaged.

Further, since the roller shaft 26, the roller 27, and the elastic member 28 can be housed in a small space and have a simple structure, it is possible to provide a small-sized and low-cost rack and pinion gear device.

In this embodiment, the pair of roller shafts 26 are arranged so as to intersect the axes at a predetermined angle, but the present invention is not limited to this, and the roller shafts 26 are arranged on the same straight line, for example. Alternatively, the pair of roller shafts 26 may be connected to each other. Further, in this embodiment, the supporting member 25 is used as the sliding contact member and the sliding contact portion 25a is formed on the supporting member 25, but the sliding contact portion may be formed on the housing 22 (support).

(Effect) According to the present invention, a pair of rollers arranged with the rack interposed therebetween are urged toward the back surface of the rack to make rolling contact, and
Since the roller is moved in the axial direction of the roller shaft by the displacement of the rack according to the meshing pressure between the rack and the pinion, the impact or the like input from the steering wheel to the rack is mitigated without bending the roller shaft. The steering feeling can be maintained well and the durability of the rack can be improved because it does not damage the back of the rack or the rollers, and the steering loss is suppressed by eliminating the lateral movement of the rack during normal steering. You can Then, these can be realized by a rack-and-pinion gear device having a simple structure, small size, and low cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are views showing an embodiment of a rack and pinion gear device according to the present invention, and FIG. 1 is a front sectional view of the rack and pinion gear device, and FIG. Is a plan view of the rolling support portion, FIGS. 3 to 5 are views showing a conventional rack and pinion gear device, and FIG. 3 is an overall configuration diagram of a steering system using the rack and pinion gear device,
FIG. 4 is a front sectional view of the rack and pinion gear device, and FIG. 5 is a front sectional view showing another conventional rack and pinion gear device. 21 …… Pinion, 22 …… Housing (support), 23 …… Rack, 23a …… Curved back (rear), 24 …… Rolling support, 25 …… Support member (sliding contact), 26 …… Roller shaft, 27 …… Roller, 28 …… Elastic member.

Claims (1)

[Scope of utility model registration request] 1. A pinion rotatably supported by a support, and a pinion that meshes with the pinion, moves axially by rotation of the pinion, and is displaceable in a direction in which the meshing depth decreases as the meshing pressure increases. In a rack-and-pinion gear device including a rack and a rolling support portion supported by a support so as to support the rack by rolling contact with the rack, a support member in which the rolling support portion is supported by the support body. A roller shaft supported by a support member so as to be substantially orthogonal to the rack, and rotatably and axially movably supported by the roller shaft. The rack is arranged so as to move in the axial direction by the displacement of the rack. And at least a pair of rollers, an elastic member that applies an urging force to the rollers so that the rollers make rolling contact with the rear surface of the rack, and the rack rear surface after a predetermined amount of movement of the rollers. Rack and pinion gearing, characterized in that it comprises a sliding member for supporting the sliding contact, the.