JP2576836Y2 - Pinion shaft structure in rack and pinion type steering device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pinion shaft structure suitable for use in a rack and pinion type steering device.

[0002]

2. Description of the Related Art A rack-and-pinion type steering device is lightweight, has a relatively simple structure, is superior in steering performance, and is advantageous in terms of space for installation in a vehicle. It has advantages and has been widely adopted in recent years. In particular, this type of rack-and-pinion type steering device can satisfy requirements to some extent in recent automobiles that are required to have conflicting demands for downsizing and a large living space. large.

[0003] Even in such a rack and pinion type steering device, there is still room for improvement in reducing the size, weight, and size of an automobile. One of the conventional techniques is to provide bearings on both sides of the meshing portion of the pinion shaft with the rack so as to maintain proper meshing. In the bearing section provided on the seat side, the dimension in the axial direction on the inner diameter side of the bearing must be ensured, and the area of the shaft support section must be ensured. The pinion type steering device was lengthened. As a result, the operation space of the driver's seat is narrowed, which is against the demand for expanding the living space.

In particular, power steering systems have recently become popular, and since their control valves are provided on the side end sides of the pinion shafts, it is desirable to minimize their axial length.

[0005] To meet such demands,
For example as viewed from the engagement portion between the rack pinion shaft, the bearing supporting portion of the pinion shaft provided on the input shaft, and configured to perform support actions by fitted the inner diameter portion of the bearing press-fitting or the like, the support portion Has been conventionally provided as close as possible to an incomplete gear portion that is continuous with a complete gear portion of a pinion that meshes with a rack.

[0006]

However, in the conventional structure, in addition to the above-described problem of lengthening the device, when a sporty and quick steering characteristic is required, the gear ratio between the pinion and the rack is reduced. Therefore, it is necessary to increase the stroke of the rack with respect to the rotation of the pinion, and inevitably the specifications of the pinion gear part tend to be large. However, this has caused a problem in terms of mounting characteristics of the bearing.

That is, the above-mentioned bearing support portion is formed at a position as close as possible to the incomplete gear portion of the pinion on the pinion shaft, with an outer diameter dimension substantially equal to the outer diameter of the pinion gear portion. Then, the bearing is press-fitted from the tip end of the pinion shaft into the support portion to perform the support action. In this case, however, the burrs at the time of gear machining in the incomplete gear portion of the pinion are provided. Due to the influence, there is a problem that it is difficult to fit and it is not possible to fit and provide a regular support portion.

This is because the pinion described above is gear-machined by, for example, hobbing, as is apparent from FIG. 3 (b) described later. It can be easily understood that such burrs inevitably cause the burrs to protrude to the outside of the gear portion, resulting in impaired mountability of the bearing. Of course, the flash in such an imperfect gear part is
Removal by a brush or the like is usually performed, but it is difficult to remove it reliably. Therefore, it is desired to take some measure that can eliminate the above-described problem when mounting the bearing.

[0009]

In order to respond to such a demand, the pinion shaft structure of the rack and pinion type steering device according to the present invention includes an incomplete gear portion which is continuous with a complete gear portion of the pinion meshing with the rack. Biting with the rack
Fit portion forming a bearing support portion at a position close from the opposite side of the, meshes with the rack of the pinion shaft on the supporting portion unit
When fitting the inner diameter portion of the bearing from the front end side, at least close to the bearing support portion with the imperfect gear portion of the pinion
The contact portion is a small diameter portion smaller than the outer diameter of the complete gear portion of the bearing support portion and the pinion.

[0010]

According to the present invention, in an incomplete gear portion of a pinion where burrs are likely to occur during gear machining of the pinion ,
Both the part close to the bearing support part is formed as a small diameter part compared to the complete gear part and the bearing support part, so when fitting the bearing to the pinion and mounting it on the support part, The effect of the generated burrs can be prevented, and the mounting of the bearing can be improved.

[0011]

1 to 3 illustrate an embodiment of a pinion shaft structure in a rack and pinion type steering device according to the present invention.
In this embodiment, a case will be described in which the present invention is applied to a rack and pinion type power steering device used for power steering illustrated in FIG.

First, the schematic structure of a power steering body in a rack and pinion type power steering apparatus to which the present invention is applied will be briefly described with reference to FIG. 2. In the figure, reference numeral 1 is connected to a steering handle (not shown). The stub shaft 2 serving as an input shaft is connected to the inner end (left end) side of the stub shaft 1 via a torsion bar 3 and has a rack tooth 4a on a rack 4 constituting a steering link mechanism (not shown). A pinion shaft having a pinion 5 to be meshed, and a projection and a groove are provided between the two shafts 1 and 2 as a fail-safe mechanism that allows relative rotation displacement within a predetermined angle range by torsion of the torsion bar 3. A safety spline portion 6 is provided interposed. The inner end of the torsion bar 3 is press-fitted and fixed to the pinion shaft 2, and the outer end extends through the stub shaft 1 to the outer end (right end) of the shaft 1. The coupling serration portion 1a of the shaft 1 with the steering handle side is connected by a connecting pin 3a which is driven into a pin insertion hole formed in co-operation with the torsion bar 3.

Reference numeral 7 denotes a body (housing) which constitutes a power steering main body. The two shafts 1 and 2 have a plurality of bearings 8 such as needle bearings and ball bearings.
A, 8B, 8C and the like are rotatably supported, and an oil seal or the like is provided at an appropriate position.

A rotor 11 constituting a rotary flow path switching valve 10 is provided inside the body 7 on the inner end side of each of the shafts 1 and 2.
And the sleeve 12 are provided integrally with each other, and are configured to switch the flow path between the oil pump P and oil tank T (not shown) and the power cylinder left and right chambers CL and CR by relative rotational displacement. I have. The rotor 11
Is formed integrally with the stub shaft 1 side, the sleeve 12 is integrally connected with the pinion shaft 2 side by pin connection, and is combined with the torsion bar 3 in a state where it can be relatively rotated and displaced. It is installed inside.

The structure of the hydraulic circuit in the rotor 11 and the sleeve 12 and the valve housing (body 7) constituting the rotary type flow path switching valve 10 is well known, and the rotors 11 slidingly contact each other are opposed to each other. A plurality of passage grooves are formed at predetermined intervals in the circumferential direction on the outer peripheral surface of the sleeve 12 and the inner peripheral surface of the sleeve 12, and a plurality of fluid supply holes and fluid discharge holes are formed at appropriate locations. The hydraulic circuit is formed by switching selectively as needed by selectively communicating and blocking these passage grooves and the like.

In the figures, reference numerals 15 and 16 denote inlet ports into which pressure oil from the oil pump P flows and return ports for returning the pressure oil to the oil tank T, and 17A and 17B denote left and right cylinder chambers of the power cylinder. Left connected to CL, CR,
At the right output port, the hydraulic displacement between these ports is arbitrarily connected and interrupted by the rotational displacement accompanying the steering operation of the flow path switching valve 10 described above, and the generation of a steering assist force by a power cylinder (not shown). Is known in the art.

According to the present invention, in the power steering apparatus as described above, as is apparent from FIGS. 1 and 2, the rack 4 which is the output shaft is a complete gear portion 5a of the pinion 5.
And the incomplete gear portion 5b of the pinion shaft 2
Wherein the bearing supporting portion 21 formed at a position close from the opposite side of the engagement portion between the rack 4, the inner diameter of the bearing 8B which supports the pinion shaft 2 in the body 7 of the pinion shaft 2 la
At the time of fitting by press fitting or the like from the front end side of the meshing portion side with the pin 4 , at least the incomplete gear portion 5 b of the pinion 5
As is clear from FIG. 3A , a portion close to the bearing support portion 21 is a small-diameter portion 20 smaller than the outer diameter of the bearing support portion 21 and the outer diameter of the complete gear portion 5a of the pinion 5. It has features in the place where it is formed.

Here, in FIG. 1 and FIG.
Reference numeral 2 denotes an annular groove formed in a portion of the bearing support 21 near the pinion 5 (that is, in the bearing fitting direction).
2 is a locking ring as locking means for locking the movement of the bearing 8B in the detaching direction. As such locking means, as conventionally known, a C-shaped retaining ring,
Various locking methods including knurling and the like can be considered. However, the present invention is not limited to this, and if the entire structure of the device can lock the bearing 8B in the axial direction and can maintain the assembled state in a required state, the above-described locking means and its annular shape can be used. It goes without saying that the groove may be omitted.

According to the above-described configuration, the incomplete gear portion 5b, which is liable to generate burrs when gearing the pinion 5, is replaced with the complete gear portion 5a and the bearing support portion 2 on the outer peripheral portion of the pinion shaft 2.
Since formed as small-diameter portion 20 outer diameter is smaller than 1, the inner diameter of the bearing 8B of the rack 4 of the pinion shaft 2
In fitting the bearing support portion 21 from the tip end side of the meshing portion side, as is apparent from FIG.
The burrs generated in the imperfect gear portion 5b described above are
Since it is easy to occur within the outer diameter of a and the inner diameter of the bearing 8B,
There is an advantage that the mountability of the bearing 8B can be improved. This is easily understood in comparison with FIG. 3B showing a conventional example .

Further, according to the present invention, if the imperfect gear portion 5b, which is the small diameter portion 20 described above, is formed of only the minimum necessary portion that interferes with the burrs when the above-described bearing 8B is fitted by fitting, In addition, the reliability of the pinion shaft 2 in terms of strength can be ensured.

The present invention is not limited to the structure of the embodiment described above, and the shape, structure, etc. of each part can be freely modified and changed as needed, and various modifications can be considered.

In the above embodiment, the case where the pinion shaft structure according to the present invention is applied to a steering device for power steering has been described. However, the present invention is not limited to this, and the steering device for manual steering is used. It will be easily understood that the above can also be applied.

[0023]

As described above, according to the pinion shaft structure of the rack-and-pinion type steering device according to the present invention, at least the bearing support is provided at an incomplete gear portion where burrs are easily generated on the pinion shaft when gearing the pinion. Close to part
Is formed as a small diameter portion smaller than the outer diameter of the complete gear portion of the bearing support portion and the pinion .
In spite of its simple structure,
The effect is excellent. That is, according to the present invention, when fitting the bearing inner diameter portion to the bearing support portion of the pinion shaft, the burrs generated in the incomplete gear portion may be located inside the outer diameter of the complete gear portion of the pinion or the inner diameter of the bearing. What happens to
Et al., Is the upper direction of the mounting of the predetermined portion of the pinion shaft bearing
Can be Also, according to the present invention, on the pinion shaft
The bearing of the bearing that supports the input shaft side of the pinion with
Because it is provided near the incomplete gear part of the ON,
The pinion shaft can be
Minimize the overall length by minimizing the axial length as much as possible
Can be achieved.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part showing an embodiment of a pinion shaft structure in a rack and pinion type steering device according to the present invention.

FIG. 2 is an overall schematic cross-sectional view showing an example of a rack and pinion type steering device for power steering suitable for applying the present invention.

FIG. 3 is a diagram for explaining the relationship between the incomplete gear portion of the pinion and the bearing, which is a feature of the present invention, in comparison with a conventional example, and (a) is a schematic exploded perspective view according to the present invention; b) is a schematic exploded perspective view showing a conventional example.

[Explanation of symbols]

 Reference Signs List 1 stub shaft 2 pinion shaft (input shaft) 4 rack (output shaft) 4a rack teeth 5 pinion 5a complete gear portion 5b incomplete gear portion 7 body (housing) 8B bearing (ball bearing) 10 flow path switching valve 20 small diameter portion 21 Bearing support 22 Ring groove 23 Locking ring (locking means)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B62D 5/22 B62D 3/12 F16H 19/04

Claims (1)

(57) [Scope of request for utility model registration] To 1. A position adjacent the opposite side of the engagement portion between the rack imperfect gear portion in the pinion shaft to perform the engagement with complete gear portion of the rack and pinion which is an output shaft, the pinion shaft In a pinion shaft structure in a rack and pinion type steering device forming a support portion of a bearing fitted from a tip end side of a meshing portion side with a rack, at least the bearing support is provided by an incomplete gear portion of the pinion.
A pinion shaft structure in a rack and pinion type steering device , wherein a portion close to the portion is formed as a small diameter portion smaller than the outer diameter of the bearing support portion and a complete gear portion of the pinion.