JP2948890B2 - Rack and pinion steering system - Google Patents

Description

The present invention relates to a rack and pinion type steering device,
In particular, it is suitable as a steering device for a vehicle having a large steering reaction force.

(Prior Art) FIGS. 6 and 7 show a conventional rack-and-pinion type hydraulic power steering apparatus, which is a helical pinion 101 interlocked with a steering handle and meshes with the pinion 101. FIG. A rack bar 103 on which a helical rack 102 is formed, a rack housing 104 that covers the pinion 101 and the rack 102, and a cylinder tube 105 integrated with the rack housing 104 and externally fitted to the rack bar 103 are provided. ing.

Ball joints 106 and tie rods are provided at both ends of the rack bar 103.
A steered wheel (not shown) is interlocked and connected via a knuckle arm 107, and the steered wheel is steered by the movement of the rack bar 103 in the rack axis direction due to the rotation of the pinion 101.

Further, an oil chamber 110 which is made oil-tight by a pair of seal members 108 and 109 is formed between the inner and outer circumferences of the rack bar 103 and the cylinder tube 105.

A piston 111 is provided on the outer periphery of the rack bar 103, and pressure oil is supplied to the one side and the other side in the longitudinal direction of the oil chamber 110 partitioned by the piston 111 via pipes 112, 112 according to the steering direction. As a result, the assisting force of the steering operation is applied to the rack bar 103.

The rack bar 103 is supported on the inner peripheral surface of the cylinder tube 105 via the bush 113 on one side in the axial direction, and is supported by the rack housing 104 via a support yoke 114 built in the rack housing 104. I have. That is, the rack bar 103 is supported at two points via the bush 113 and the support yoke 114 (the rack bar 103 is connected to the inner peripheral surface of the cylinder tube 105 via the seal members 108 and 109 and the seal member 116 on the outer periphery of the piston 111). , But the seal member is not a supporting point because it is easily deformed).

The position of the support yoke 114 can be freely changed in the direction of adjusting the engagement between the rack 102 and the pinion 101 (the left-right direction in FIG. 6) by advancing and retracting the plug 115 screwed into the rack housing 104 in the screwing direction. ing. Thereby, by changing the position of the rack bar 103 in the direction of adjusting the engagement between the rack 102 and the pinion 101 via the support yoke 114,
It is assumed that a smooth meshing state can be obtained.

Further, the support yoke 114 is urged by the compression spring 117 to come into contact with the rack bar 103, thereby allowing the rack bar 103 to move in the meshing adjustment direction due to a gear cutting manufacturing error or the like, thereby obtaining a smooth meshing state. It is assumed.

(Problems to be Solved by the Invention) When the steering device having the above configuration is used for a large vehicle, or when the inclination between the rack bar 103 and the tie rod 107 becomes large due to the layout of the vehicle,
Since the steering reaction force acting on the rack bar 103 from the steered wheels increases, it is necessary to take measures for reducing the deformation of the rack bar 103 and improving the strength.

To cope with this, the diameter of the rack bar 103 is increased, or the rack bar 103 is moved not only through the bush 113 but also through a plurality of bushes to the cylinder tube 105.
For example, it is conceivable to increase the number of support points by supporting the inner peripheral surface.

However, if the diameter of the rack bar 103 is increased,
There is a problem that the entire device is unnecessarily increased in size due to an increase in the center distance between the pinion 101 and the pinion 101 and an increase in the effective length of the tooth portion of the pinion 101.

When the rack bar 103 is supported on the inner peripheral surface of the cylinder tube 105 at a plurality of positions, the rack bar 103 cannot move in the mesh adjustment direction, and the mesh adjustment between the rack 102 and the pinion 101 via the support yoke 114 cannot be performed. There is a problem.

Further, when the pinion 101 and the rack 102 are helical, the meshing portion is meshed while generating a force to rotate the rack bar 103 about the rack axis. Therefore, when a large force acts to rotate the rack bar 103 around the rack axis based on the steering reaction force, the meshing state changes in the conventional structure, and a smooth meshing state cannot be obtained. There is.

(Means for Solving the Problems) It is an object of the present invention to provide a rack and pinion type steering device that can solve the above-described problems of the conventional technology.

The features of the present invention include a helical pinion for transmitting steering operation input, a rack bar formed with a helical rack meshing with the pinion, and a steering rod interlocked with steered wheels, The steering rod has a cylindrical shape, and a cutout for exposing the rack is formed in the steering rod, into which the rack bar is inserted. The rack bar moves along with the steering rod in the axial direction of the rack and the axis of the rack. The point is that it is connected to the center so as to be relatively rotatable.

Further, the rack bar is connected to the steering rod so as to be repositionable in the direction of adjusting the engagement of the rack with the pinion, and the support member supporting the rack bar so as to allow movement in the direction of adjusting the engagement includes a rack supporting the pinion. The support member is attached to the housing, the through hole of the support member is formed in the steering rod, and the support member and the through hole are engaged so that the rotation of the rack around the axis of the rack with respect to the pinion of the steering rod is restricted. Is preferred.

(Operation) According to the configuration of the present invention, the transmission of the steering operation input from the pinion causes the rack bar and the steering rod to move together so as to steer the steered wheels.

In addition, the reduction of the deformation and the improvement of the strength due to the steering reaction force between the steering rod and the rack bar can be performed by increasing the diameter of the steering rod or by increasing the number of supporting portions of the steering rod. There is no need to increase.

Further, even if the position of the steering rod cannot be changed in the direction of adjusting the meshing of the rack with the pinion due to an increase in the number of support points, the position of the rack bar is changed in the direction of adjusting the meshing of the steering rod with respect to the steering rod. The meshing can be adjusted.

Further, since the rack bar is connected to the steering rod so as to be relatively rotatable about the rack axis, a force for rotating the steering rod about the rack axis based on the steering reaction force is transmitted to the rack bar. Even if the pinion and the rack are helical, it is possible to prevent the meshing state from changing.

Also, if the steering rod rotates about the rack axis with respect to the pinion, it may interfere with the pinion.
The rotation of the steering rod is regulated. Rather than providing a dedicated configuration for this rotation control, the rotation is controlled by engaging the support member of the rack bar with the through hole of the support member formed on the steering rod, thereby simplifying the structure. It is planned.

(Example) Hereinafter, an example of the present invention is described with reference to drawings.

FIGS. 1 to 4 show a rack-and-pinion type hydraulic power steering device for an automobile. A helical pinion 2 connected to a handle (not shown) via an input shaft 1 and a helical rack 3 meshing with the pinion 2 are formed. Rack bar 4 is provided.

The input shaft 1 and the pinion 2 are connected to a rack housing 6.
(The left and right sides of the rack housing 6 are symmetrical in FIG. 1, so that a part of the right side is Not shown).

Flanges 8 are formed on both sides of the rack housing 6 in the vehicle width direction, and cylindrical cylinder tubes 9 are connected by bolts 10 via the flanges 8 to be integrated. The cylinder tube 9 is fixed to a vehicle body (not shown).

To the rack housing 6 and each cylinder tube 9,
A cylindrical steering rod 11 is inserted, and the rack bar 4 is inserted into the steering rod 11.

At approximately the center of the steering rod 11 in the vehicle width direction,
A notch 5 is provided so that the rack 3 is exposed to the outside of the steering rod 11.
Are engaged with the pinion 2.

The rack bar 4 and the steering rod 11 are connected so as to move along the rack axis direction,
Steering wheels (not shown) are connected to each end of the steering rod 11 via a ball joint 12. As a result, the rotation of the pinion 2 causes the rack bar 4 and the steering rod 11 to move together in the rack axis direction, and the steered wheels are steered.

A bush 13 is attached to each outer end of the cylinder tube 9 in the vehicle width direction, and a steering rod 11 is inserted into the bush 13 via seal members 14 and 15 so as to be slidable in the rack axis direction. .

Further, pistons 16 are provided on the outer periphery of the steering rod 11 on both sides of the rack housing 6, respectively.
Each piston 16 has a sealing member 17 with respect to the cylinder tube 9.
Slidably in the rack axis direction.

Thereby, a pair of oil chambers 18 closed by the bush 13 and the piston 16 are formed between the inner and outer circumferences of the steering rod 11 and the cylinder tube 9.

By supplying the pressure oil to one of the pair of oil chambers 18 according to the steering direction, an assisting force of the steering operation is applied to the steering rod 11 via the piston 16.

In order to adjust the engagement between the pinion 2 and the rack 3, the position of the rack bar 4 can be adjusted relative to the pinion 2 in the horizontal direction in FIG.

That is, a circumferential groove 19 is formed on each of the outer circumferences at both ends in the axial direction of the rack bar 4, and an O-ring 20 as an elastic body is fitted into the circumferential groove 19, and the ring
21 is fitted outside. An O-ring 23, which is an elastic body, is fitted into a circumferential groove 22 formed on the outer periphery of the ring body 21, and the ring body 21 is inserted into the steering rod 11 via the O-ring 23.

As a result, the rack bar 4 is supported by the steering rod 11 via the O-rings 20 and 23, and the position thereof can be changed in the direction of adjusting the engagement between the pinion 2 and the rack 3 by the elastic deformation of the O-rings 20 and 23. ing.

The rack bar 4 and the steering rod 11 are relatively rotatable about the rack axis. That is,
The rack bar 4 is slidable relative to the steering rod 11 about the center of the rack axis via the O-rings 20 and 23 and the ring body 21.

As a result, the steering rod 11
Is prevented from being transmitted to the rack bar 4. Therefore, pinion 2
And the rack 3 are helical and mesh with each other while generating a force to rotate the rack bar 4 about the rack axis at the meshing portion, even if a large steering reaction force acts. The smooth engagement between the pinion 2 and the rack 3 can be maintained.

A support yoke 24 is attached to the rack housing 6 as a support member for the rack bar 4.
The support yoke 24 has a cylindrical outer surface, one end of which is in contact with the outer peripheral surface of the rack bar 4, and the other end of which is inserted into the plug 25. The plug 25 is screwed into the rack housing 6 via a male screw on the outer periphery, and a lock nut
Fixed by 26. In addition, a compression spring 27 that engages with the support yoke 24 and the plug 25 is built in the support yoke 24 and urges the support yoke 24 in the direction of contact with the rack bar 4.

The support yoke 24 can be moved and adjusted in the direction of adjusting the engagement between the pinion 2 and the rack 3 by moving the plug 25 in and out of the rack housing 6 in the screwing direction.

The position change of the support yoke 24 adjusts the position of the rack bar 4 in the engagement adjustment direction, and the engagement between the pinion 2 and the rack 3 is adjusted, so that a smooth engagement state is obtained.

Further, since the support yoke 24 is urged in the direction of contact with the rack bar 4 via the compression spring 27, the movement of the rack bar 4 in the direction of adjusting the meshing due to a manufacturing error of the gear cutting is allowed, and the support yoke 24 is smoothly moved. It is assumed that a proper meshing state is obtained.

Since the support yoke 24 passes through the steering rod 11, a through hole 28 is formed in the steering rod 11. The through hole 28 is a long hole elongated in the rack axis direction so that the steering rod 11 does not interfere with the support yoke 24 when moving in the rack axis direction.

The short diameter of the through hole 28 is substantially equal to the outer diameter of the support yoke 24. Thus, rotation of the steering rod 11 about the rack axis with respect to the pinion 2 is restricted by engaging the outer periphery of the support yoke 24 with the inner periphery of the through hole 28.

As described above, the rotation of the steering rod 11 about the rack axis with respect to the pinion 2 is restricted, so that the steering rod 11 is prevented from interfering with the pinion 2.

Note that, as a structure in which the outer periphery of the plug 25 is engaged with the inner periphery of the through hole 28 as a support member, the rotation of the steering rod 11 about the rack axis with respect to the pinion 2 may be restricted.

The rack bar 4 and the steering rod 11 are connected so as to move together in the rack axis direction as described above. For this reason, a stopper is provided for restricting relative movement of the rack bar 4 with respect to the steering rod 11 in the rack axis direction. In this embodiment, the ball joints 12 at both ends of the steering rod 11 also serve as stoppers.

That is, the ball joint 12 includes a ball holding cylinder 29, a ball 30 rotatably held in the ball holding cylinder 29, a block 31 for supporting the ball 30 via a seat 33, and a ball 31 and a block 31. A cap 32 screwed into the ball holding cylinder 29 to prevent the ball holding cylinder 29 from coming off the
A compression spring 34 is provided in the cap 32 and presses and biases the block 31 against the ball 30. Further, a connection shaft 35 is connected and fixed to the ball 30.

Each ball joint 12 is screwed to a female thread 37 formed on the inner circumference of both ends of the steering rod 11 via a male thread 36 formed on the outer circumference of the ball holding cylinder 29.
The ball joint 12 comes into contact with each end face of the rack bar 4.

Accordingly, relative movement of the rack bar 4 in the rack axis direction with respect to the steering rod 11 is restricted by the ball joint 12 also serving as a stopper, and the rack bar 4 and the steering rod 11 are steered in the rack axis direction, that is, steered wheels. It is assumed that they move together in the direction in which they are made to move.

Also, the relative movement of the rack bar 4 in the rack axis direction with respect to the steering rod 11 is regulated,
It is possible to prevent the steering wheel from rattling during the steering operation.

As described above, the mounting of the ball joint 12 also serving as the stopper is performed by screwing into the female thread portions 37 formed on the inner circumferences at both ends of the steering rod 11, utilizing the fact that the steering rod 11 is formed in a cylindrical shape. As a result, the structure is simplified.

The relative movement of the ring body 21 in the rack axis direction with respect to the rack bar 4 is restricted by being sandwiched between the ball joint 12 and the inner peripheral step 39 of the steering rod 11.

Further, a lock nut 38 that is in contact with the end surface of the steering rod 11 is screwed into the male screw portion 36 of each of the ball holding cylinders 29 to prevent the ball holding cylinder 29 from loosening. The lock nut 38 is integrally formed with a restricting portion 40 that protrudes radially outward to prevent overstroke. When the restricting portion 40 contacts the bush 13, the steering rod 11 is restricted from moving more than necessary in the rack axis direction.

A connection block 42 is screwed to the connection shaft 35 via a lock nut 41, and a steering wheel is connected to the connection block 42 via a knuckle arm or the like. This allows
By adjusting the screwing amount of the connecting block 42 into the connecting shaft 35, the toe-in of the vehicle can be adjusted.

The supply of pressurized oil to the oil chamber 18 is performed by a rotary valve 43 fitted to the input shaft 1 and connected to the pinion 2.
Done through.

That is, pressure oil supplied from a tank (not shown) via a pump reaches an oil passage between the inner and outer circumferences of the rotary valve 43 and the input shaft 1 from a supply hole 44 formed in the rack housing 6. A connection hole 45 communicating from this oil passage to the right steering oil chamber 18
And a connection hole 46 connected to the left steering oil chamber 18 are formed in the rack housing 6. The rotary valve 43 rotates together with the pinion 2. The input shaft 1 and the rotary valve 43
Rotary valve 43 and input shaft 1
An oil passage between the inner and outer circumferences is communicated with the connection hole 45 or the connection hole 46, and pressure oil is supplied to one oil chamber 18 according to the steering direction, and oil is supplied from the other oil chamber 18 to the rack housing 6. It is returned to the tank from the formed discharge hole 47.

In order to communicate the connection holes 45 and 46 with the oil chamber 18, the pipes are not used in the above embodiment, and the blocks 48 integrated with the cylinder tube 9 and the rack housing 6 on both sides of the rack housing 6 in the vehicle width direction are used. And an oil passage hole 49 for connecting the connection holes 45, 46 and the oil chamber 18 to each block 48.
Is formed.

An bellows cover 50 made of an elastic material is provided so as to cover the steering rod 11 and the ball joint 12 protruding from both ends of the cylinder tube 9, and is fixed to the outer periphery of the connecting shaft 35, the ball holding cylinder 29 and the cylinder tube 9. It is fixed by a ring or the like.

According to the steering device, the steering rod
The support 11 is supported at three places via the support yoke 24 and the two bushes 13, and is more supported than the conventional support at two places via the support yoke and one bush. And the bending deformation of the steering rod 11 and the rack bar 4 due to the steering reaction force is reduced, which is suitable for use in a large vehicle having a large steering reaction force.

Further, in order to improve the strength against the steering reaction force and reduce the deformation, it is sufficient to increase the diameter of the steering rod 11, and it is not necessary to increase the rack bar 4, and the distance between the shafts of the pinion 2 and the rack 3 and the pinion The effective length of 2 can be made constant,
The entire device is not unnecessarily enlarged.

In addition, even if the position of the steering rod 11 cannot be changed in the direction of adjusting the engagement between the pinion 2 and the rack 3 due to an increase in the number of supporting portions of the steering rod 11, the position of the rack bar 4 is changed in the direction of adjusting the engagement. A good meshing state can be obtained.

The present invention is not limited to the above embodiment.

For example, in the above embodiment, the ball joint 12 also serves as a stopper that regulates the relative movement of the rack bar 4 and the steering rod 11 in the rack axis direction. However, as shown in FIG. , A stopper 60 may be provided separately.

That is, each stopper 60 has a male screw portion 61 formed on the outer circumference, is screwed into a female screw portion 37 formed on the inner circumference of both ends of the steering rod 11, and comes into contact with both ends of the rack bar 4. This restricts the relative movement with respect to 11 in the rack axis direction. The stopper 60 has a tool engagement hole 62 formed therein.

In the embodiment of FIG. 5, a ring portion 63 is formed integrally with the stopper 60 in place of the ring body 21 in the above embodiment, and the peripheral groove 22 is formed in the ring portion 63 so that the O-ring 23 is formed.
Is fitted to have a function similar to that of the ring body 21.

Further, in the above-described embodiment, the toe-in adjustment of the vehicle is enabled by adjusting the screwing amount of the connection block 42 into the connection shaft 35.In this embodiment, the ball joint 12 needs to have a stopper function. Since there is no ball joint 12
The toe-in adjustment is performed by adjusting the amount of screwing into the steering rod 11. For this reason, the connecting shaft 35 and the connecting block 42 do not need to be separated from each other. Therefore, the connecting shaft 35 and the connecting block 42 are integrally formed and reduced in size, and are suitable for a case where there is not enough space.

Other configurations are the same as those of the above-described embodiment, and the same portions are denoted by the same reference numerals.

In the above embodiment, the joint 12 is a ball joint, but may be a pin joint, for example.

Further, the number of supporting portions of the steering rod 11 may be increased or decreased as compared with the above embodiment.

Further, the present invention is applicable not only to a hydraulic power steering device but also to a manual steering device and an electric power steering device.

(Effect of the Invention) According to the present invention, the steering rod has a cylindrical shape,
Since the rack bar is inserted into the steering rod, the reduction and improvement of the strength due to the steering reaction force can be performed by increasing the diameter of the steering rod and the number of supporting points, etc. It is not necessary, and it is possible to prevent the entire apparatus from becoming unnecessarily large.

In addition, since the rack bar is connected to the steering rod so as to be rotatable relative to the center of the rack axis, it is possible to prevent the meshing state between the helical pinion and the helical rack from being changed by steering reaction force, and to achieve a smooth meshing state. Can be maintained.

In addition, since the rotation of the steering rod about the center of the rack axis with respect to the pinion is restricted, interference between the steering rod and the pinion is prevented. Simplification can be achieved.

[Brief description of the drawings]

1 to 5 relate to an embodiment of the present invention. FIG. 1 is a front sectional view of a steering device, FIG. 2 is a side sectional view of the steering device, and FIG. FIG. 4 is a rear view of a main part of the steering apparatus, FIG. 5 is a front sectional view of a main part of the steering apparatus according to a different embodiment, FIG. 6 is a side sectional view of a conventional steering apparatus,
FIG. 7 is a partially cutaway front view of a conventional steering device. 2 ... pinion, 3 ... rack, 4 ... rack bar, 5
…… Notch, 6… Rack housing, 11… Steering rod, 24… Support yoke (support member), 28 ……
Through holes.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-49-61828 (JP, A) JP-A-4-118371 (JP, A) JP-A-54-104132 (JP, A) JP-A 61-61 125968 (JP, A) JP 2-3752 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) B62D 5/00-5/30 B62D 3/12

Claims (2)

(57) [Claims] A helical pinion for transmitting a steering operation input, a rack bar formed with a helical rack meshing with the pinion, and a steering rod interlocked to a steering wheel, the steering rod being a cylinder The steering rod is formed with a notch for inserting the rack bar and exposing the rack,
A rack and pinion type steering device, wherein the rack bar is connected to the steering rod so as to move in the axial direction of the rack and to be relatively rotatable about the axis of the rack. 2. A rack bar is connected to a steering rod so as to be repositionable in a direction in which the rack meshes with the pinion, and a support member for supporting the rack bar so as to allow movement in the direction of meshing adjustment. The support member is attached to the supporting rack housing, and a through hole of the support member is formed in the steering rod, and the support member and the through hole are engaged with each other so that rotation of the rack around the axis of the steering rod with respect to the pinion is restricted. The rack-and-pinion type steering apparatus according to claim 1, wherein: