JP2003118593A - Vehicle steering expansion shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a stable sliding load, surely prevent play and transmit torque in a highly rigid condition. SOLUTION: An angular key 8 is fitted in an axially unmovable manner to an approximately square axial groove 5 of a female shaft 2 via a preload wavy plate spring 7, and an approximately triangular head portion of the angular key 8 is slidably fitted to an approximately triangular axial groove 3 of a male shaft 1. An approximately triangular protruding portion 9 formed ranging from the inner periphery face of the female shaft 2 inward to the radial direction is slidably fitted to an approximately triangular axial groove 4 of the male shaft 1. The angular key 8 and the protruding portion 9 play the roles of a key during torque transmission and of a sliding surface (sliding contact) during sliding, respectively.

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. 5 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 combined telescopic shaft for vehicle steering, an angular key is axially immovably fitted to an axial groove formed on the inner peripheral surface of the female shaft through an elastic body, and is attached to the outer peripheral surface of the male shaft. The substantially square head of the square key is slidably fitted in the formed axial groove, and the inner circumference of the female shaft is formed in at least one axial groove formed on the outer peripheral surface of the male shaft. It is characterized in that at least one angular protrusion formed inward in the radial direction from the surface is slidably fitted.

Further, in the telescopic shaft for vehicle steering of the present invention, the two axial grooves formed on the outer peripheral surface of the male shaft,
It is preferable to slidably fit two angular protrusions formed inward in the radial direction from the inner peripheral surface of the female shaft.

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

As described above, according to the present invention, the rectangular key is fitted in the axial groove formed on the inner peripheral surface of the female shaft through the elastic body for preload so as to be immovable in the axial direction. A substantially square head of a square key is slidably fitted in an axial groove formed on the outer peripheral surface of the male shaft. An angular groove formed on the outer peripheral surface of the male shaft and radially inward from the inner peripheral surface of the female shaft is slidably fitted. The square key and the ridge portion function as a key during torque transmission and also as a sliding surface (sliding contact) during sliding.

When torque is not transmitted, the rectangular key is preloaded by the leaf spring, which is an elastic body, to the extent that there is no play in the axial groove of the male shaft, so there is no play between the male and female shafts. 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.

At the time of transmitting torque, since the leaf spring which is an elastic body can restrain the square key and the ridge portion in the circumferential direction, the looseness in the rotation direction between the male shaft and the female shaft is surely secured. It is possible to prevent the torque from being 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, in the present invention, since the number of parts is small (no roller or retainer is required), there is an advantage that the assembly is easy and the cost is low. Also, since the balls are in point contact, the surface pressure increases when torque is applied to the shaft.Therefore, many balls should be arranged, or both male and female shafts should be heat treated to increase their hardness. There must be. 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.

[0015]

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) shows the telescopic shaft separated. It is a perspective view of a state. FIG. 2 is a cross-sectional view taken along the line AA of FIG. FIG. 3 is an exploded perspective view of the telescopic shaft for vehicle steering 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.

As shown in FIG. 2, on the outer peripheral surface of the male shaft 1,
Three substantially triangular axial grooves 3 and 4 are formed extending at equal intervals in the circumferential direction at 120 ° intervals. The inner peripheral surface of the female shaft 2 accommodates a square bottom portion of a square key 8 to be described later 1
A number of substantially rectangular axial grooves 5 are formed.

A square key 8 is fitted in a substantially square axial groove 5 of the female shaft 2 through a corrugated leaf spring 7 for preload so as to be immovable in the axial direction. The substantially triangular head portion of the square key 8 is slidably fitted in the substantially triangular axial groove 3.

Two substantially triangular axial grooves 4 of the male shaft 1.
2 formed inward in the radial direction from the inner peripheral surface of the female shaft 2.
Individual substantially triangular projections 9 are slidably fitted.

The square key 8 and the protruding portion 9 serve as a key when transmitting torque and also as a sliding surface (sliding contact) when sliding.

Several screw holes 10 are formed in the female shaft 2, and correspondingly, several holes 1 are also formed in the leaf spring 7.
1 is formed, and corresponding to this, a square key 8
Several recesses 12 are also formed in the flat bottom of the.

A male screw 13 screwed into the screw hole 10 is fitted into the concave portion 12 of the square key 8 through the hole 11 of the leaf spring 7, whereby the square key 8 and the leaf spring 7 are axially moved. I am unable to move. Further, the male screw 13 can adjust the elastic force of the leaf spring 7.

In the expansion / contraction shaft configured as described above, the square key 8 and the ridge portion 9 function as a key when transmitting torque and also as a sliding surface (sliding contact) during sliding. It is like this.

When torque is not transmitted, the leaf spring 7 pre-loads the square key 8 into the axial groove 3 of the male shaft 1 to such an extent that it does not rattle, so that there is a play between the male shaft 1 and the female shaft 2. The sticking can be reliably prevented, and the male shaft 1 and the female shaft 2 can slide in the axial direction with a stable sliding load without rattling.

At the time of torque transmission, the leaf spring 7 can restrain the square key 8 and the ridge portion 9 in the circumferential direction, so that the rotation direction play between the male shaft 1 and the female shaft 2 is surely secured. Therefore, the torque can be transmitted in a highly rigid state.

The square key 8 may be heat-treated and polished. It is also possible to use a rectangular key 8 whose surface is treated with a resin film. A resin film containing molybdenum disulfide may be formed on the surface of the rectangular key 8. PTFE on the surface of the axial grooves 3, 4 of the male shaft 1
A resin film of (tetrafluoroethylene) may be formed. A solid or hollow steel material produced by cold drawing the male shaft 1 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. Further, on the surface of the protrusion 9 of the female shaft 2 and the surface of the rectangular key 8, PTF is
A resin film of E (ethylene tetrafluoride) may be formed.

As described above, the square key 8 and the protrusion 9 are
It also serves as a key for transmitting torque between the male shaft 1 and the female shaft 2, and is also a sliding surface that makes sliding contact with the inner peripheral surface of the female shaft 2. The advantages of the conventional spline fitting are as follows. -By applying a preload between the male shaft, the square key and the female shaft, there is no play and a stable sliding load can be obtained. -The surface pressure can be kept lower than when using rolling elements such as conventional needle rollers. -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.

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. 4 shows a second embodiment of the present invention.
It is a cross-sectional view of a telescopic shaft for vehicle steering according to an embodiment.

In the second embodiment, the outer peripheral surface of the male shaft 1 is formed with two substantially triangular axial grooves 3 and 4 extending equidistantly at intervals of 180 degrees in the circumferential direction. There is. Male axis 1 of 1
One substantially triangular protrusion portion 9 formed in the substantially triangular axial groove 4 from the inner peripheral surface of the female shaft 2 toward the inner side in the radial direction.
Is slidably fitted. Other configurations and the like are similar to those of the above-described first embodiment.

The groove formed on the male shaft, the ridge formed on the female shaft, and the square key shown in the above-described embodiment have a substantially triangular shape, but the force applied to the groove during torque transmission is small. A substantially trapezoidal shape in which a surface orthogonal to the contact surface is arranged may be used.

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

[0034]

As described above, according to the present invention,
In the axial groove formed on the inner peripheral surface of the female shaft, through the elastic body,
A square key is attached, and a substantially square head of the square key is slidably fitted in an axial groove formed on the outer peripheral surface of the male shaft. An angular groove formed on the outer peripheral surface of the male shaft and radially inward from the inner peripheral surface of the female shaft is slidably fitted. The square key and the ridge portion function as a key during torque transmission and also as a sliding surface (sliding contact) during sliding.

When torque is not transmitted, the rectangular key is preloaded by the leaf spring, which is an elastic body, to the extent that there is no rattling in the axial groove of the male shaft, so there is no rattling between the male and female shafts. 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.

At the time of torque transmission, since the leaf spring which is an elastic body can restrain the rectangular key and the ridge portion in the circumferential direction, the looseness in the rotational direction between the male shaft and the female shaft is surely secured. It is possible to prevent the torque from being 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 of the telescopic shaft in a separated state.

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

3 is an exploded perspective view of the telescopic shaft for vehicle steering shown in FIG. 1. FIG.

FIG. 4 is a transverse cross-sectional view of a telescopic shaft for vehicle steering according to a second embodiment of the present invention.

FIG. 5 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 7 Leaf spring (elastic body) 8 square key 9 ridges 10 screw holes 11 holes 12 recess 13 male screw

Claims (3)

[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, wherein an axial groove formed on an inner peripheral surface of the female shaft. , A rectangular key is fitted through an elastic body so as to be immovable in the axial direction, and a substantially angular head of the rectangular key is slidably fitted in an axial groove formed on the outer peripheral surface of the male shaft. The at least one axial groove formed on the outer peripheral surface of the male shaft, and the at least one angular protrusion formed radially inward from the inner peripheral surface of the female shaft. Telescopic shaft for vehicle steering, which is fitted so that it can move freely. 2. The two axial grooves formed on the outer peripheral surface of the male shaft are provided with two angular protrusions formed radially inward from the inner peripheral surface of the female shaft. The telescopic shaft for vehicle steering according to claim 1, wherein the telescopic shaft is movably fitted. 3. The telescopic shaft for vehicle steering according to claim 1, wherein the elastic body is a leaf spring.