JP3284289B2 - Rack and pinion steering system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rack and pinion type steering device which is widely used as one type of steering device for automobiles.

[0002]

2. Description of the Related Art A rack-and-pinion type steering apparatus houses a rack shaft slidably in an axial direction inside a rack housing extending in the left-right direction of a vehicle body. The pinion shaft is supported rotatably around the axis inside a gear housing integrally provided by intersecting the pinion and the pinion shaft is meshed with a part of the rack shaft, while the rack housing Both ends of the rack shaft projecting from both sides are connected to left and right steering wheels (generally, front wheels), and the tip of a pinion shaft projecting from the gear housing is connected to a steering wheel (steering wheel) to perform steering operation. The rotation of the pinion shaft generated in accordance with the above is converted into the movement of the rack shaft in the axial direction, and the left and right steering wheels are steered, that is, the steering is performed.

In the above-described rack and pinion type steering apparatus, it is important that an appropriate preload is applied to a meshing portion between the pinion shaft and the rack shaft so that the two mesh substantially without backlash. For this reason, conventionally, a pressing member (support yoke) is fitted in a mounting hole formed at a corresponding position of the housing, and the rack shaft is pressed from the back side by the support yoke, and the rack shaft meshes with the pinion shaft. Pressing means configured to press against the part is used.

FIG. 3 is a longitudinal sectional view showing a main part of a conventional rack and pinion type steering apparatus provided with a general pressing means. Pinion shaft 2 with pinion 20 around the middle
As shown, a pair of ball bearings 21 and 22 on both sides of the pinion 20 are
Thus, the pinion shaft 2 is rotatably supported coaxially inside the gear housing A, and the projecting end of the pinion shaft 2 projecting upward from the gear housing A is connected to a steering wheel (not shown).

A rack housing B having a cylindrical shape is provided in the middle of the gear housing A in such a manner that the shaft centers are crossed, and the rack housing B is slidable in the axial direction in the rack housing B. The rack shaft 3 is supported on the rack. Rack axis 3
Are rack teeth 30 formed over a suitable length outside the middle part.
The rack teeth 30 are meshed with the pinion 20 at the intersection with the gear housing A. Further, both ends of the rack shaft 3 projecting to both sides of the rack housing B are respectively connected to left and right steering wheels (not shown), and the rotation of the pinion shaft 2 caused by the steering operation is performed by the pinion 20. The gear is converted into sliding of the rack shaft 3 by meshing with the rack teeth 30, and the left and right steering wheels are steered.

The rack and pinion type steering device constructed as described above has a yoke housing C integrally projecting at a crossing position of the gear housing A and the rack housing B in a direction substantially orthogonal to each of them. The pressing means is formed inside the yoke housing C.

That is, the yoke housing C is provided with a mounting hole 40 having a circular cross section penetrating the shaft center portion. The support yoke 4 having a cylindrical shape is fitted in the mounting hole 40 in the axial direction. It is freely inserted. The distal end of the support yoke 4 facing the inside of the gear housing A has an arch shape corresponding to the outer shape of the rack shaft 3, and has a sliding plate 41 on the outer periphery of the rear side of the rack shaft 3 (opposite to the meshing portion with the pinion 20). Are in sliding contact with each other. The base end of the support yoke 4 is screwed into the inner periphery of the other side of the yoke housing C to lock nut 43.
The support cap 42 is fixed to the inner surface of the support cap 42, and is pressed inward, that is, urged toward the rack shaft 3 by a pressing spring 44 interposed between the support cap 42 and the support cap 42. I have.

The support yoke 4 is pressed against the rear surface of the rack shaft 3 by the spring force of the pressing spring 44,
The rack shaft 3 is supported while being pressed toward the pinion shaft 2, and a preload is applied to a meshing portion between the rack teeth 30 and the pinion 20 to maintain a good meshing state between the two. The preload is appropriately adjusted by increasing or decreasing the screwing amount of the support cap 42.

Further, a road surface reaction force applied to the steered wheels is introduced into the rack shaft 3 during the steering operation as a reverse input acting in the axial direction, and the rack shaft 3 exerts a component force of the reverse input. To be displaced in a direction away from the pinion 20. The support yoke 4 includes a support cap
The slide shaft can slide along the mounting hole 40 within a predetermined gap secured between the rack shaft 3 and the pinion shaft. 2 stably maintains a good meshing state. Furthermore, a helical gear is often used as the pinion 20 and the rack teeth 30. In this case, the reverse input component acts on the support yoke 4 in the axial direction of the pinion shaft 2. The arch shape at the tip of the support yoke 4 is necessary to support this component force.

[0010]

In the conventional rack and pinion type steering apparatus having the pressing means constructed as described above, the sliding of the rack shaft 3 accompanying the rotation of the pinion shaft 2 causes the rear surface of the rack shaft 3 to move. On the other hand, the contact area between the support yoke 4 and the support yoke 4 is large because the front end of the support yoke 4 has the above-mentioned arch shape, which is a resistance that hinders the sliding of the rack shaft 3 and the pinion shaft. There is a disadvantage that the transmission efficiency from the rack 2 to the rack shaft 3 is inevitably reduced, and the steering feeling is deteriorated.

The force acting on the rack shaft 3 due to the above-described reverse input is a force in a direction perpendicular to the pressure surface of the rack teeth 30 and the pinion 20, and the support yoke 4 only has its own axial length direction. Instead, the direction perpendicular to the plane of FIG.
The axial component of the rack shaft 3 also acts. Therefore, due to repetition of sliding of the support yoke 4 in the mounting hole 40, uneven wear easily occurs on the inner surface of the mounting hole 40 and / or the support yoke 4. The support yoke 4 vibrates inside, causing unpleasant noises due to the collision between the two, and also has the disadvantage that the purpose of maintaining a good meshing state between the pinion shaft 2 and the rack shaft 3 cannot be fulfilled.

In order to solve these difficulties, Japanese Patent Application Laid-Open No. 2-270674 filed by the applicant of the present invention discloses a pivot shaft orthogonal to the axis of the rack shaft 3 at the tip of the support yoke 4 inserted into the mounting hole 40. There is disclosed a rack and pinion type steering device in which a support roller is rotatably mounted around, and the support roller is brought into rolling contact with the rear surface of the rack shaft 3 to constitute a pressing means.

According to this configuration, the sliding of the rack shaft 3 accompanying the rotation of the pinion shaft 2 occurs against the rolling resistance of the support roller, so that the sliding resistance of the rack shaft 3 is maintained at a low level. The former difficulty is solved. Further, the axial component of the rack shaft 3 generated by the reverse input from the steered wheels is absorbed by the rotation of the support roller, and does not hinder the sliding of the support yoke 4. The latter difficulty associated with the occurrence of wear is also eliminated.

However, when the pinion 20 and the rack teeth 30 are helical gears, the acting force on the support yoke 4 is, as described above, the axial component of the pinion shaft 2 generated by the inclination of the pinion 20 and the rack teeth 30. The rotational force in the plane including the axes of the pinion shaft 2 and the rack shaft 3 acts on the support yoke 4 by the action of the component force.
Therefore, the orthogonal relationship between the pivot axis of the support roller pivotally supported by the support yoke 4 and the axis of the rack shaft 3 cannot be maintained, and
Rolling of the support roller caused by sliding of the rack shaft 3 is hindered, and the sliding resistance of the rack shaft 3 fluctuates, so that a stable steering feeling may not be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and the support of the rack shaft at the meshing portion with the pinion shaft and the maintenance of the proper meshing state between the pinion shaft and the rack shaft are performed for steering. An object of the present invention is to provide a rack-and-pinion type steering device that can surely perform smooth sliding of a rack shaft without obstructing it and stably obtain a good steering feeling.

[0016]

A rack and pinion type steering apparatus according to the present invention supports a pinion shaft and a rack shaft in a common housing, meshes with each other, and operates the pinion shaft by operating a steering wheel. The rotation is converted into sliding in the axial direction of the rack shaft to perform steering,
In a rack-and-pinion type steering device, the rack shaft is pressed against the pinion shaft by a supporting roller that rolls and contacts the pinion shaft, and pressing means for applying a predetermined preload to a meshing portion of both shafts is provided inside a mounting hole provided in the housing.
The pressing means is fixed inside the mounting hole.
Fixed holder and the support roller are rotatably held,
A roller holder fitted <br/> the through hole of rectangular cross section which penetrates the axial center portion of the fixing holder, the urging force is added to the roller holder, and urging means for pressing the support rollers to the rack shaft it characterized by comprising a.

[0017]

According to the present invention, a rectangular cross section penetrating the shaft center is provided.
A fixed holder with a through hole is fixedly supported in the mounting hole provided in the housing, and the support roller is rotatable.
The roller holder for holding fitted in the through hole, the through hole
Restricts rotation relative to the fixed holder and housing.
Presses the rack shaft via the support rollers added biasing force Ri by the biasing means into a bundle has been roller holder, and configured to impart a preload to meshing portions of the pinion shaft, the pressing due to the axial force of the pinion shaft Rotate the means in a rectangular cross-section through-hole
The rotation of the support shaft is prevented by the rotation constraint of the roller holder, and the rolling of the support roller accompanying the sliding of the rack shaft is performed stably.

Further, the rotation restraining action of the roller holder is performed not by the housing itself but by a through hole having a rectangular cross section provided in a fixed holder fixed inside the housing.
Allowed to facilitate the processing required for rotation restraint and said
During over time damage of the through holes, the replacement of the fixed holder
Be prepared to respond .

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a longitudinal sectional view showing a main part of a rack and pinion type steering device according to the present invention.

In FIG. 1, reference symbol A denotes a gear housing, and a pinion shaft 2 is disposed inside the gear housing A. The pinion shaft 2 includes a pinion 20 formed at an appropriate length in the middle thereof, and is rotatably supported coaxially inside the gear housing A by a pair of ball bearings 21 and 22 on both sides of the pinion 20. Have been. A rack housing B having a cylindrical shape is integrally connected to the gear housing A with the axes thereof crossing each other. A rack shaft 3 is slidably supported in the rack housing B in the axial direction. Have been. The rack shaft 3 penetrates through the inside of the gear housing A so as to intersect one side of the pinion 20, and rack teeth 30 formed over the rack shaft 3 over an appropriate length are formed on the pinion 20. It is engaged.

One end of the pinion shaft 2 is connected to a gear housing A
And is connected to a steering wheel (steering wheel) not shown. Further, both ends of the rack shaft 3 are projected from both sides of the rack housing B, respectively.
They are respectively connected to left and right steering wheels (not shown).

The above configuration is the same as that of the conventional rack and pinion type steering apparatus shown in FIG. 3, but the feature of the apparatus of the present invention is that the pre-load is applied to the meshing portion between the pinion 20 and the rack teeth 30 so as to improve the performance. In order to maintain a proper meshing state, the pressing means for pressing the rack shaft 3 against the pinion shaft 2 is provided. The pressing means is formed inside a yoke housing C which is integrally provided at a crossing position between the gear housing A and the rack housing B in a direction substantially orthogonal to the gear housing A and the rack housing B.

[0023] attached to the yoke housing C, which is open at the intersection of the pinion shaft 2 and the rack shaft 3, from the rear side of the rack shaft 3 (opposite side of the engagement portion of the pinion shaft 2) in the interior of the gear housing A Hole 10 is formed through ,
A fixed holder 11 is fitted in the mounting hole 10.
Fixing holder 11 includes a stepped surface provided on the inner back side of the mounting hole 10, both sides were sandwiched with the and the distal end surface of the other side support cap 12 screwed into the opening of the mounting hole 10, the inside of the yoke housing C It is fixed to. Support cap 12
After being screwed into the mounting hole 10, the positioning can be fixed by tightening the lock nut 13 to the outer periphery.

The fixed holder 11 has a through hole penetrating the shaft center.
A hole 14 is formed, and a roller holder is formed in the through hole 14.
15 are fitted slidably in the axial direction and non-rotatable. The roller holder 15 rotatably holds the support roller 1 having a drum-shaped outer shape. The support roller 1 is provided with a mounting hole formed in the yoke housing C.
10, it faces the inside of the gear housing A through an opening on one side, and as shown in the drawing, the rear side of the rack shaft 3 (pinion 20).
(On the opposite side of the meshing part).

FIG. 2 shows a fixed holder 11, a roller holder 15,
FIG. 2 is an exploded perspective view of the support roller 1. Fixed holder 11
Is a member of the short-sized cylindrical shape having an outer diameter corresponding to the mounting hole 10, transmural penetrating the axial center portion of the fixing holder 11
Through holes 14 are formed to have a rectangular cross-section.

The roller holder 15 inserted into the through hole 14
Is a configuration in which a pair of side plates 15a, 15a having a width corresponding to the length of one side of the through hole 14 are opposed to each other at a distance corresponding to the length of the other side, and are connected in a gate shape by a connecting plate 15b. The support roller 1 is inserted between the side plates 15a and 15a, and a support hole formed therethrough at a corresponding position thereof.
The support pins 16 are supported by pivot pins 17 which are driven from the outside. This pivot is, as shown in FIG.
The sliding plates 1a, 1a are interposed between both side plates 15a, 15a of the supporting roller 1 and the sliding bushes 1b are interposed between the pivot pin 17 and the pivot hole of the supporting roller 1, respectively. Thus, the rotation of the support roller 1 is generated without resistance.

The roller holder 15 to which the support roller 1 is attached as described above is fitted into the through hole 14 of the fixed holder 11 inserted into the mounting hole 10 of the yoke housing C, and is fixed by screwing the support cap 12. It is mounted by the procedure of holding and fixing the holder 11. The screwing of the support cap 12 is performed by interposing a pressing spring 18 between the inner surface of the supporting cap 12 and the connecting plate 15b of the roller holder 15 facing the supporting cap 12, and presses the roller holder 15 after mounting. The spring 18 biases inward, that is, toward the rack shaft 3 side.

The fixed holder 11 before the support cap 12 is tightened can be rotated in the mounting hole 10 of the yoke housing C. By utilizing this, the rotation of the support roller 1 with respect to the rack shaft 3 is utilized. The contact state can be optimized. This optimization is performed, for example, by a procedure in which the rack shaft 3 is appropriately slid when the support cap 12 is appropriately screwed. That is, when the rolling contact state of the support roller 1 is not appropriate, frictional resistance accompanying the sliding of the rack shaft 3 is applied to the support roller 1, and the support roller 1 is rotated together with the roller holder 15 and the fixed holder 11 around the axis of the mounting hole 10. The support roller 1 is rotated to a position where the frictional resistance is minimized, specifically, the pivot pin 17 of the support roller 1 is equilibrated to a position orthogonal to the axial direction of the rack shaft 3, and the rolling contact state of the support roller 1 is changed. Be optimized.

[0029] clamping the support cap 12 after this, while when positioned by screwing a lock nut 13, the solid <br/> constant holder 11, which is non-rotatably restrained in within the attachment hole 10, the fixing holder 11 The relative rotation between the roller and the roller holder 15 is restrained at the stage of assembling the latter into the rectangular through hole 14 formed in the former, so that the support roller 1 obtained as described above The proper rolling contact state with the rack shaft 3 is stably maintained thereafter.

In the device of the present invention constructed as described above, when a steering operation for steering is performed, the pinion shaft 2 rotates by an amount corresponding to the operation amount in this operation direction, and this rotation is performed by the pinion. The engagement between the rack teeth 30 and the rack teeth 30 converts the sliding into sliding in the axial direction of the rack shaft 3 and is transmitted to the left and right steering wheels. Steering according to the steering operation is performed by these steering operations. At this time, the rack shaft 3 comes into contact with the outer periphery of the rack shaft 3 and is supported by the support roller 1 urged by the spring force of the pressing spring 18.
As a result, an appropriate preload is applied to the meshing portion between the rack teeth 30 on the rack shaft 3 side and the pinion 20 on the pinion shaft 2 side, and a good meshing state can be obtained between the two. I have.

A road surface reaction force applied to the steered wheels is introduced to the rack shaft 3 during the steering operation as a reverse input acting in the axial direction, and the rack shaft 3 is displaced in a direction away from the pinion 20. However, the supporting roller 1 that comes into contact with the rack shaft 3 is provided together with the roller holder 15 that holds the supporting roller 1 in the through hole.
14 can be slid within a predetermined gap secured between the support cap 12 and the support cap 12, whereby the rack shaft 3 can be supported while following the displacement by this sliding. And a good meshing state with the above can be stably maintained.

Further, the supporting roller 1 which comes into contact with the rack shaft 3
As described above, the force in the axial direction of the rack shaft 3 and the force in the axial direction of the pinion shaft 2 act on each other as described above, but the former is absorbed by the rotation of the support roller 1 about the pivot axis, and The rotation that occurs in the plane including the axis of the shaft 2 and the rack shaft 3 is performed by a roller holder that holds the support roller 1.
15 is surely regulated by being restricted in rotation. Accordingly, the sliding of the rack shaft 3 is smoothly performed against the rolling resistance of the support roller 1 that rolls while maintaining an appropriate rolling contact state, so that a good steering feeling can be stably obtained. Become.

[0033]

Further, in the device of the present invention, the through hole 14 provided in the fixed holder 11 fixed to the yoke housing C
Roller holder 15 is inserted, and the operation from the rack shaft 3
If the through-hole 14 is damaged over time due to the sliding of the roller holder 15 due to the force , or if a processing error is found during assembly , the fixing of the fixed holder 11 can be performed without forcing the entire housing to be replaced . By replacing
Can be. In addition, the axis of the cylindrical fixed holder 11
The through-hole 14 penetrates without using a special processing method
The roller holder 15 can be formed with high precision,
Make sure that the bundle
It can be done without resistance.

[0035]

As described in detail above, in the device according to the present invention, the fixing hook fixed to the mounting hole provided in the housing is provided.
A roller holder is fitted into the through-hole having a rectangular cross-section penetrating the shaft center portion of the rudder, and the rack shaft is pressed against the pinion shaft by a supporting roller rotatably held by the roller holder. The sliding of the rack shaft during the steering operation is guided by the rolling of the rack shaft, so that the rack shaft slides against the external force acting in various directions while properly maintaining the meshing state with the pinion shaft. The steering can be performed smoothly, and a good steering feeling can be stably obtained.

Further, since the through-hole into which the roller holder is inserted is formed in the fixed holder fixed inside the housing, the through-hole can be processed easily and with high precision.
Thus , the present invention has excellent effects such as easy replacement in the event of damage over time or processing errors.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a device of the present invention.

FIG. 2 is an exploded perspective view of a pressing means in the device of the present invention.

FIG. 3 is a longitudinal sectional view showing a main part of a conventional rack and pinion type steering device.

[Explanation of symbols]

Reference Signs List 1 support roller 2 pinion shaft 3 rack shaft 10 mounting hole 11 fixing holder 12 support cap 14 through hole 15 roller holder 17 pivot pin 18 push spring 20 pinion 30 rack tooth A gear housing B rack housing C yoke housing

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B62D 3/12

Claims (1)

(57) [Claims] 1. A pinion shaft and a rack shaft are supported in a common housing and meshed with each other to convert rotation of the pinion shaft caused by operation of a steering wheel into sliding in the axial direction of the rack shaft. The rack shaft is pressed against the pinion shaft by a supporting roller that is in contact with the rack shaft, and pressing means for applying a predetermined preload to a meshing portion of the both shafts is provided in the mounting hole provided in the housing. In the rack and pinion type steering device provided in the inside, the pressing means may be fixed inside the mounting hole.
A holder, said support roller rotatably held, the solid
And fitting interpolated roller holder into the through hole of rectangular cross section which penetrates the axial center portion of the constant holder, a biasing force on the roller holder addition,
A rack and pinion type steering device comprising: urging means for pressing the support roller against the rack shaft.