JP2003063414A - Vehicle steering extension rod - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit the torque in the high rigid condition by implementing a stable sliding load and securely preventing the generation of looseness. SOLUTION: Three needle rollers 7 and 8 are interposed in three pairs of axial grooves 3, 4 and 5 formed in a male shaft 1 and a female shaft 3, and these needle rollers 7 and 8 work as a key when transmitting the torque, and while work as a sliding surface (sliding feeling) when sliding. When not transmitting the torque, since the needle rollers 7 and 8 are previously pressurized to a degree to prevent generation of looseness in the inner peripheral surface of the female shaft 2, the generation of looseness between the male shaft 1 and the female shaft 2 is securely prevented, and the male shaft 1 and the female shaft 2 can thereby slide on each other in the axial direction with a stable sliding load without generating looseness. When transmitting the torque, a plate spring 9 is elastically deformed to constrain the needle roller 7 in the circumferential direction to securely prevent the generation of looseness in the rotating direction between the male shaft 1 and the female shaft 2, and the torque can be thereby transmitted in the high rigid condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telescopic shaft for a vehicle steering that realizes a stable sliding load, reliably prevents rattling, and can transmit torque in a highly rigid state.

[0002]

2. Description of the Related Art FIG. 8 shows a steering mechanism of a general automobile. In the figure, a and b are expansion and contraction axes. The telescopic shaft a is formed by spline-fitting a male shaft and a female shaft. The telescopic shaft a absorbs axial displacement generated when a vehicle travels, and is mounted on the steering wheel. Performance that does not transmit displacement or vibration is required. In such performance, the vehicle body has a sub-frame structure, a portion c for fixing the upper portion of the steering mechanism and a frame e to which the steering rack d is fixed are separate bodies, and an elastic body f such as rubber is provided between them. It is generally required in the case of a structure that is fastened and fixed via. As another case, when the steering shaft joint g is fastened to the pinion shaft h, an operator sometimes needs a telescopic function because the telescopic shaft is once contracted and then fitted and fastened to the pinion shaft h. . Further, the telescopic shaft b at the upper part of the steering mechanism is also the one in which the male shaft and the female shaft are spline-fitted, and such an telescopic shaft b has an optimum position for the driver to drive the automobile. In order to obtain the above, the function of moving the position of the steering wheel i in the axial direction and adjusting the position is required. Therefore, the function of expanding and contracting in the axial direction is required. In all of the above cases, the telescopic shaft is required to reduce rattling noise at the spline, reduce rattling on the steering wheel, and reduce sliding resistance during axial sliding movement. To be done.

For this reason, the expansion / contraction shafts a and b have been conventionally used.
Nylon film is coated on the spline part of the male shaft, and grease is applied to the sliding part to prevent metal noise,
In addition to absorbing or mitigating metal tapping noise, etc., we have reduced sliding resistance and rotation direction play. In this case, in the step of forming the nylon film, cleaning of the shaft → application of a primer → heating → nylon powder coating → rough cutting → finish cutting → selective fitting with a female shaft is performed. The final cutting process is performed by selecting a die according to the accuracy of the female shaft that has already been processed.

[0004]

However, since it is necessary to minimize the backlash while minimizing the sliding load of the expansion / contraction shaft, in the final cutting process, the overpin diameter size differs by several microns. It is inevitable to select and process the blades according to the female axis, resulting in higher processing costs. In addition, the wear of the nylon film progresses over the course of use, and the play in the rotational direction increases.

Further, under the condition of being exposed to high temperature in the engine room, the volume of the nylon film changes, the sliding resistance becomes extremely high, and the abrasion is significantly promoted, so that the play in the rotating direction becomes large.

Therefore, there is a demand for a simple and inexpensive structure that can suppress, for a long period of time, the expansion and contraction shafts used for automobile steering shafts from generating abnormal noise due to rotational direction play and deterioration of steering feeling.

The present invention has been made in view of the above-mentioned circumstances, and realizes a stable sliding load, reliably prevents backlash in the rotational direction, and provides torque in a highly rigid state. An object is to provide a telescopic shaft for vehicle steering that can be transmitted.

[0008]

In order to achieve the above object, the telescopic shaft for vehicle steering according to the present invention is incorporated in a steering shaft of a vehicle, and a male shaft and a female shaft are non-rotatably and slidably fitted. In the telescopic shaft for vehicle steering, the at least three needle rollers interposed in at least three pairs of axial grooves formed on the outer peripheral surface of the male shaft and the inner peripheral surface of the female shaft, respectively, and The needle roller is interposed between the needle roller and the axial groove of the male shaft, and when the torque is not transmitted, the needle roller is preloaded on the inner peripheral surface of the female shaft, and when the torque is transmitted, the needle roller is elastically deformed. And at least one elastic body that constrains in the circumferential direction.

Further, in the telescopic shaft for vehicle steering according to the present invention, it is preferable that the elastic body is a leaf spring.

As described above, according to the present invention, the three needle rollers are respectively provided in the three pairs of axial grooves formed on the male shaft and the female shaft, and these needle rollers are used for transmitting torque. In addition to playing the role of a key, it also plays the role of a sliding surface (sliding contact) during sliding.

Further, when torque is not transmitted, the needle roller is preloaded by the leaf spring, which is an elastic body, to the extent that there is no rattling on the inner peripheral surface of the female shaft, so there is rattling between the male shaft and the female shaft. This can be reliably prevented, and the male shaft and the female shaft can slide in the axial direction with a stable sliding load without rattling.

Further, during torque transmission, the leaf spring, which is an elastic body, is elastically deformed to restrain the needle roller in the circumferential direction, so that there is certain play in the rotational direction between the male shaft and the female shaft. Therefore, the torque can be transmitted in a highly rigid state.

Incidentally, Japanese Patent Laid-Open No. 2001-50293,
German Patent Publication DE 3730393 A1 discloses a structure in which a plurality of balls are inserted in axial grooves formed in a male shaft and a female shaft and preloaded by an elastic body. On the other hand, the present invention has the advantages that the number of parts is small (there are at most six rollers and no cage is required), so that the assembly is easy and the cost is low. Also, since the balls are in point contact, the surface pressure rises when torque is applied to the shaft, so many balls should be arranged or
Both the male and female shafts must be heat treated to increase the hardness. Further, in the ball type, it is necessary to pre-load with a spring or the like from the left and right axial directions so as to prevent the balls and the cage from becoming loose, and hold the fixed position. Further, in the above-mentioned German publication, the assembly order is "inner shaft → ball → compression spring → outer shaft", but in the present invention, "inner shaft (male shaft) → compression spring → roller → outer shaft ( Female shaft) ", and the assembly order is different. Due to this difference, in the present invention, by disposing the leaf spring on the inner shaft (male shaft), the leaf spring can be easily fixed to the male shaft side by the retaining ring. Since the leaf spring can be fixed by the retaining ring, the desired preload can be obtained without slipping between the male shaft and the female shaft even when there is only one leaf spring when torque is applied.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A telescopic shaft for vehicle steering according to an embodiment of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 (a) is a side view of a telescopic shaft for vehicle steering according to a first embodiment of the present invention, and FIG. 1 (b) is a perspective view thereof. . Figure 2
[FIG. 2] is a transverse sectional view taken along the line AA of FIG. FIG. 3 is a perspective view showing a state in which the male shaft and the female shaft of the telescopic shaft shown in FIG. 1 are separated. 4 (a) is a plan view of the leaf spring, and FIG. 4 (b) is an exploded perspective view of the vehicle steering telescopic shaft shown in FIG.

As shown in FIG. 1, a telescopic shaft for vehicle steering (hereinafter referred to as an "expandable shaft") comprises a male shaft 1 and a female shaft 2 which are fitted in a mutually non-rotatable and slidable manner.

On the outer peripheral surface of the male shaft 1, three axial grooves 3 and 4 are formed extending at equal intervals in the circumferential direction at 120 degrees, and at the inner peripheral surface of the female shaft 2. Also, three axial grooves 5 are equally formed in the circumferential direction at equal intervals of 120 degrees. As shown in FIG. 2, among these axial grooves, the male shaft 1
Steps 6 are formed on both sides of the axial groove 3 for locking a leaf spring 9 described later.

Three needle rollers 7 and 8 of the same shape are interposed in these three pairs of axial grooves 3, 4, and 5.
These needle rollers 7 and 8 function as keys during torque transmission and also as sliding surfaces (sliding contact) during sliding.

A leaf spring 9 is interposed between the one axial groove 3 of the male shaft 1 and its needle roller 7. When the torque is not transmitted, the leaf spring 9 prevents the needle roller 7,
8 is preloaded against the female shaft 2 to the extent that there is no rattling, while elastically deforming during torque transmission, the needle roller 7 acts to restrain the needle roller 7 in the circumferential direction between the male shaft 1 and the female shaft 2. Has become.

As shown in FIG. 4B, two circumferential grooves 10 are formed in the male shaft 1 where the three needle rollers 7 and 8 and both ends of the leaf spring 9 are located. I am doing it.
Further, as shown in FIG. 4A, projections 9a are formed on both end portions of the leaf spring 9 in the axial direction. As a result, as shown in FIG. 3, the two retaining rings 11 are fitted in the circumferential groove 10 to fix the three needle rollers 7 and 8 in the axial direction, and the projection 9a of the leaf spring 9 is provided. To lock the leaf spring 9 in the axial direction. Further, at the time of assembling this telescopic shaft, as shown in FIG. 3, in a state where the three needle rollers 7, 8 and the leaf spring 9 are fixed to the axial grooves 3, 4 of the male shaft 1 by the retaining ring 11, The male shaft 1 is fitted to the female shaft 2.

As shown in FIG. 2, the leaf spring 9 is engaged with the step portions 6 on both sides of the axial groove 3 of the male shaft 1 at both ends thereof, whereby the torque is transmitted in the circumferential direction. The entire leaf spring 9 does not move.

The leaf spring 9 has a corrugated shape and has a recess at the center, and the needle roller 7 is provided in the recess at the center.
Is to be placed. Since the radius of curvature (R1) of the central depression of the leaf spring 9 is smaller than the radius of curvature (R2) of the needle roller 7, the leaf spring 9 and the needle roller 7 have two points (X) in FIG. ) Contact. Further, the leaf spring 9 comes into contact with both edges of the axial groove 3 of the male shaft 1 at two points (Y) in FIG. As a result of such two-point contact (X, Y), a minute gap (Z) is formed between the leaf spring 9 and the needle roller 7.
x) exists, and a minute gap (Zy) exists between the leaf spring 9 and the axial groove 3.

In the telescopic shaft configured as described above, when the torque is not transmitted, the leaf rollers 9 cause the needle rollers 7, 8 to move.
Is preloaded against the female shaft 2 to the extent that there is no rattling, it is possible to reliably prevent rattling between the male shaft 1 and the female shaft 2, and the male shaft 1 and the female shaft 2 are It can slide in the axial direction with a stable sliding load without rattling.

When the torque is not transmitted, the needle roller 7 is located in the center of the axial groove 3 of the male shaft 1, and a minute gap (Zx) exists between the leaf spring 9 and the needle roller 7. , A small gap (Z
y) is present.

On the other hand, at the time of torque transmission, the leaf spring 9 is elastically deformed to restrain the needle roller 7 between the male shaft 1 and the female shaft 2 in the circumferential direction. Therefore, it is possible to reliably prevent looseness in the rotation direction between the male shaft 1 and the female shaft 2,
Torque can be transmitted in a highly rigid state.

During torque transmission, the minute gap (Zx) between the leaf spring 9 and the needle roller 7 and the leaf spring 9
The minute gap (Zy) between the axial groove 3 and the axial groove 3 becomes smaller, and when the torque input further increases, the leaf spring 9 is sandwiched between the needle roller 7 and the axial groove 3, The contact point (X) between the leaf spring 9 and the needle roller 7 and the contact point (Y) between the leaf spring 9 and both edges of the axial groove 3 are substantially aligned in the circumferential direction to which torque is applied. Torque can be transmitted in a highly rigid state.

Further, two needle rollers 8 are attached to the male shaft 1.
When it is arranged, the surface of the male shaft 1 in the vicinity of the needle roller 8 may be caulked so that the needle roller 8 may be integrated so as not to separate from the male shaft 1. The needle rollers 7 and 8 may be heat-treated and polished. You may use the thing which gave the resin film process to the surface of the needle rollers 7 and 8. Needle roller 7,
A resin film containing molybdenum disulfide may be formed on the surface of No. 8. A resin film of PTFE (tetrafluoroethylene) may be formed on the surfaces of the needle rollers 7 and 8. Male shaft 1
A solid or hollow steel material manufactured by cold drawing may be used. A solid or hollow aluminum material produced by cold drawing the male shaft 1 may be used. A solid steel material manufactured by cold forging the male shaft 1 may be used. A hollow steel material manufactured by cold drawing the female shaft 2 may be used. A hollow aluminum material manufactured by cold drawing the female shaft 2 may be used. The female shaft 2 may be carbonitrided. The axial groove 5 of the female shaft 2 may be arranged such that arcs larger than the radius of the needle roller 8 face each other with the center portion of the groove as a boundary, and in this case, the needle roller 8 and the axial groove 5 are aligned with each other. Two
Touched by points. The axial groove 4 of the male shaft 1 may be arranged such that arcs larger than the radius of the needle roller 8 face each other with the center portion of the groove as a boundary, and in this case, the needle roller 8 and the axial groove 4 are aligned. They are touching at two points. A resin film of PTFE (tetrafluoroethylene) may be formed on the surface of the axial groove 5 of the female shaft 2.

As described above, the needle rollers 7 and 8 serve as a key for transmitting torque between the male shaft 1 and the female shaft 2, and also on the sliding surface which makes sliding contact with the inner peripheral surface of the female shaft 2. is there. The advantages of the conventional spline fitting are as follows.・ Needle rollers are mass-produced products and are extremely low cost.・ Since the needle roller is polished after heat treatment,
High surface hardness and excellent wear resistance. -Since the needle roller is polished, the surface roughness is fine and the friction coefficient when sliding is low, so the sliding load can be kept low.・ The length and arrangement of the needle roller can be changed according to the operating conditions, so without changing the design concept.
It can support various applications.・ Depending on the conditions of use, it may be necessary to further reduce the friction coefficient during sliding. At this time, the sliding characteristics can be changed by surface-treating only the needle roller, so there is no need to change the design concept. , Can be applied to various applications. -By applying a preload between the male shaft, the needle roller and the female shaft, there is always no backlash and a stable sliding load can be obtained. -Because a leaf spring is used as an elastic body, it has much better heat resistance than rubber and polymer materials and can withstand use in the engine room. -Because the male and female shafts are made of drawn material, they have excellent straightness and can stabilize the sliding load. -Because a drawing material is used for the male shaft and the female shaft, even if the cross-sectional shape is irregular, the desired shape can be made at low cost without cutting. -The weight of the male shaft can be reduced by using a material such as aluminum that has a lower specific gravity than steel. At this time, since a needle roller having excellent wear resistance is used for the sliding surface, it is possible to reduce the weight without impairing the wear resistance performance.

Comparing these, the following can be said compared with the conventional products.・ Low cost.・ Stable low slide load can be obtained.・ There is no play.・ Excellent wear resistance. -Excellent heat resistance. -It is possible to reduce weight. -Easy to assemble. -It can be used for all usage conditions without changing the design concept.

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention.
FIG. 3 is a perspective view showing a state in which a male shaft and a female shaft of the telescopic shaft for vehicle steering according to the embodiment are separated. FIG. 6 is an exploded perspective view of the telescopic shaft shown in FIG.

In the present embodiment, two sets of structures composed of the needle rollers 7 and 8, the leaf spring 9 and the retaining ring 11 described above are provided, and these two sets of structures are arranged in parallel in the axial direction. . Other configurations and the like are similar to those of the above-described first embodiment.

In the present embodiment, the needle roller is divided in the axial direction even when the male shaft and the female shaft have a long fitting length, so that the sliding resistance of the first embodiment is smaller than that of the first embodiment. It is possible to prevent the increase and to maintain the rigidity in the direction perpendicular to the axis. Further, even when the straightness of the male shaft or the female shaft or both of them is not good or there is a bend, the influence can be reduced by dividing the needle roller in the axial direction, which is desirable. The sliding load can be obtained.

(Third Embodiment) FIG. 7 shows a third embodiment of the present invention.
FIG. 3 is an exploded perspective view of the telescopic shaft for vehicle steering according to the embodiment.

In this embodiment, the needle roller 8 that does not come into contact with the leaf spring 9 is composed of two roller segments 8a that are axially separated. Other configurations and the like are similar to those of the above-described first embodiment. In addition, also in this embodiment, the same effect as that of the second embodiment can be obtained.

The present invention is not limited to the above-described embodiment, but can be modified in various ways.

When the telescopic shaft is cut in the direction perpendicular to the axis,
Although the present application uses three rollers, it will be compared with the case of using two or four rollers. When a preload is applied, the preload is evenly applied if the contact is made at three points, and a stable sliding load is obtained. When the load is applied in two directions perpendicular to the axis. Due to the 0 ° 90 ° phase difference, the rigidity is significantly different. At 4 places, there is always one place where you can play.

[0037]

As described above, according to the present invention,
Three needle rollers are installed in each of the three pairs of axial grooves formed on the male shaft and the female shaft. These needle rollers function as keys for torque transmission and sliding during sliding. It plays a role of surface (sliding contact).

Further, when the torque is not transmitted, the leaf roller is preloaded by the leaf spring to the extent that there is no rattling on the inner peripheral surface of the female shaft, so that rattling between the male shaft and the female shaft is reliably prevented. In addition, the male shaft and the female shaft can slide in the axial direction with a stable sliding load without rattling.

Further, during torque transmission, the leaf spring elastically deforms to constrain the needle roller in the circumferential direction, so that it is possible to reliably prevent looseness in the rotational direction between the male shaft and the female shaft. The torque can be transmitted in a highly rigid state.

[Brief description of drawings]

FIG. 1A is a side view of a telescopic shaft for vehicle steering according to a first embodiment of the present invention, and FIG. 1B is a perspective view thereof.

FIG. 2 is a cross-sectional view taken along the line AA of FIG.

FIG. 3 is a perspective view showing a state in which a male shaft and a female shaft of the telescopic shaft shown in FIG. 1 are separated.

FIG. 4A is a plan view of a leaf spring, and FIG.
It is an exploded perspective view of the expansion-contraction shaft shown in FIG.

FIG. 5 is a perspective view showing a state in which a male shaft and a female shaft of a telescopic shaft for vehicle steering according to a second embodiment of the present invention are separated.

6 is an exploded perspective view of the telescopic shaft shown in FIG.

FIG. 7 is an exploded perspective view of a telescopic shaft for vehicle steering according to a third embodiment of the present invention.

FIG. 8 is a side view of a steering mechanism portion of a general automobile.

[Explanation of symbols]

1 male axis 2 female shaft 3,4 axial groove 5 Axial groove 6 steps 7,8 Needle roller 9 leaf spring 10 circumferential groove 11 retaining ring

Claims (2)

[Claims] 1. A telescopic shaft for vehicle steering, wherein a male shaft and a female shaft are non-rotatably and slidably fitted to a steering shaft of a vehicle, the outer peripheral surface of the male shaft and the inner peripheral surface of the female shaft. At least three needle rollers respectively inserted in at least three pairs of axial grooves formed in the above, and between one of the needle rollers and the axial groove of the male shaft, when torque is not transmitted. At least one elastic body that pre-loads the needle roller on the inner peripheral surface of the female shaft and elastically deforms during torque transmission to constrain the needle roller in the circumferential direction. Telescopic shaft for vehicle steering. 2. The telescopic shaft for vehicle steering according to claim 1, wherein the elastic body is a leaf spring.