JP2000168598A - Assembling method for power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To establish an assembling method for a power steering device capable of installing a worm shaft and a torsion bar in the condition that the neutral position of a rotary valve is kept accurately and suppressing the component costs, etc. SOLUTION: A torsion bar 9 is pressed to a hollow 6 of a worm shaft 7 by a provisionally setting screw 37 driven into a threaded hole 36 in a worm shaft 7, and pin holes are bored in the worm shaft 7 and torsion bar 9 from the side opposite the acting direction of the pressing force of the screw 37, and a fix pin is inserted into the pin hole so that the worm shaft 7 and torsion bar 9 are coupled together. In the boring process for the pin holes, holes having a diameter greater than that of the threaded hole 36 are formed while the force acting direction of a machining tool is put identical to the axis of the provisionally setting screw 37.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of assembling a power steering device for operating a power assist actuator by switching a rotary valve while generating a pseudo reaction force with a torsion bar.

[0002]

2. Description of the Related Art A conventional integral type power steering apparatus shown in FIGS. 4 to 6 is provided with a rotary pool 2 and a valve sleeve 3 in a valve case 1 of a rotary valve V. The rotary pool 2 is connected to a stub shaft 5 via a pin 4, and the stub shaft 5 is linked to a steering wheel (not shown). Therefore, when the steering wheel is turned, the stub shaft 5 rotates and the rotary pool 2 also rotates. The valve sleeve 3 is provided with a worm shaft 7 having a hollow portion 6 formed therein.
And is rotatably supported by a bearing 8 provided on the valve case 1.

The stub shaft 5 and the worm shaft 7 are connected via a torsion bar 9. That is, one end of the torsion bar 9 is fixed to the stub shaft 5 by the fixing pin 10, and the other end is fixed by the fixing pin 11 in the hollow portion 6 of the worm shaft 7.

The power assisting actuator A has a piston 13 slidably incorporated in a housing 12 and pressure chambers 14 and 15 on both sides. One of the pressure chambers 14 and 15 communicates with the pump and the other communicates with the tank in accordance with the switching position of the rotary valve V. A ball screw 17 that meshes with a worm gear 16 formed on the outer periphery of the worm shaft 7 is provided at the center of the piston 13. On one side of the piston 13 thus formed, a rack 18 is formed, and a sector gear 19 is engaged with the rack 18. The sector gear 19 is linked to a pitman arm (not shown). Therefore, when the piston 13 moves, the sector gear 19 rotates to rotate the pitman arm, and steers wheels (not shown) in a predetermined direction.

When the stub shaft 5 is rotated by turning the steering wheel, the rotational force is transmitted to the worm shaft 7 via the torsion bar 9. At this time, since the worm shaft 7 is linked to the wheel via the piston 13 and the sector gear 19, the worm shaft 7 does not rotate due to the frictional force of the wheel and the like. Therefore, when the stub shaft 5 rotates as described above, the torsion bar 9 is twisted.

Accordingly, the rotary pool 2 fixed to the stub shaft 5 and the valve sleeve 3 fixed to the worm shaft 7 rotate relative to each other, and the rotary valve V
Switch. For example, by switching the rotary valve V, if one pressure chamber 14 communicates with the pump and the other pressure chamber 15 communicates with the tank, the piston 1
3 moves to the right in the drawing, and the sector gear 19 rotates clockwise in the drawing. Conversely, when one of the pressure chambers 14 communicates with the tank and the other pressure chamber 15 communicates with the pump, the sector gear 19 rotates counterclockwise. The turning direction of the wheel is determined according to the turning direction of the sector gear 19.

As described above, in the power assisting device that generates the pseudo reaction force by the torsion bar 9, when the rotary valve V is maintained at the neutral position, the torsion bar 9 must be in a normal state without being twisted. However, depending on the fixing position of the fixing pins 10 and 11 for fixing the torsion bar 9, the torsion bar 9
Is in the normal state, the rotary valve V may deviate from the neutral position.

Therefore, conventionally, as shown in FIG. 5, a fixed pin 1 is attached to the stub shaft 5 and one end of the torsion bar 9.
Pin holes 20 and 21 for inserting 0 are formed, and the other end of the torsion bar 9 is left as it is. Also,
As shown in FIG. 6, a pair of temporary fixing screw holes 27 and 28 are formed in the worm shaft 7 in the radial direction.
The angle θ1 from the axis 29 of the fixing pin 11 to be inserted,
θ2 is made equal to each other within a range of 90 degrees or less.
However, a space is provided between the two temporary fixing screw holes 27 and 28 so that the fixing pin 11 can be inserted.

After the above, first, the pin hole 2
The stub shaft 5 and one end of the torsion bar 9 are fixed by inserting the fixing pins 10 into 0 and 21. Then, by combining the rotary pool 2 fixed to the stub shaft 5 and the valve sleeve 3 fixed to the worm shaft 7, the torsion bar 9 is incorporated into the hollow portion 6 of the worm shaft 7 while adjusting their neutral positions. Next, the temporary fixing screw 3 is inserted into each of the temporary fixing screw holes 27 and 28.
The torsion bar 9 is temporarily fixed in the hollow portion 6 of the worm shaft 7 by screwing the 0 and 31. At this time, since the temporary fixing screws 30 and 31 maintain the same angles θ1 and θ2 with respect to the axis 29 as described above, the torsion bar 9 is pressed against the pressure contact p in the hollow portion 6. Therefore, the torsion bar 9 is stably supported at the three points of the press contact point p and the pair of temporary fixing screws 30 and 31.

With the torsion bar 9 supported at three points as described above, the fixing pin 11 is inserted between the temporary fixing screw holes 27 and 28 from the direction of the arrow 32 which is the direction of the pressure contact p. The hole processing of the pin holes 33 and 34 is performed. When the hole is drilled in the direction of arrow 32 in this manner, the force at the time of the drilling acts on the pressure contact p. Therefore, the position of the torsion bar 9 does not shift even if any strong force acts during the processing. The above pin hole 3
After forming 3, 34, the fixing pin 11 is inserted therein to fix the torsion bar 9 and the worm shaft 7 integrally formed with the valve sleeve 3. Then, after fixing the torsion bar 9 and the valve sleeve 3, the temporary fixing screws 30, 31 are removed. With this configuration, when the torsion bar 9 is in the normal state, the rotary valve V does not deviate from the neutral position.

[0011]

In the above-mentioned conventional assembling method, two temporary fixing screw holes 27 and 28 must be formed, so that a processing cost is required. In addition, these two temporary fixing screw holes 27 and 28
1 must be assembled, so that the assembling work cost is also increased. Moreover, since the two temporary fixing screws 30 and 31 assembled in this manner are to be removed again, the operation cost is further increased. SUMMARY OF THE INVENTION It is an object of the present invention to provide a power steering system capable of assembling a worm shaft and a torsion bar while accurately maintaining a neutral position of a rotary valve V, and capable of reducing parts costs, machining costs, and assembling work costs. An object of the present invention is to provide a method for assembling the device.

[0012]

According to the present invention, a rotary valve is constituted by a rotary pool which rotates integrally with a stub shaft, and a valve sleeve which rotates relative to the rotary pool and rotates integrally with a hollow worm shaft. It is premised on a method of assembling a power steering device in which one end of a torsion bar is fixed to a stub shaft, and then the other end of the torsion bar is fixed to the worm shaft with a fixing pin penetrating through the hollow portion of the worm shaft.

A temporary fixing screw hole is formed in the worm shaft in the radial direction, and a torsion bar is connected to one side of the worm shaft by a temporary fixing screw projecting from the temporary fixing screw hole into a hollow portion of the worm shaft. And a hole forming step of forming a pin hole in the worm shaft and the torsion bar from a direction opposite to the direction of action of the pressing force of the temporary fixing screw, and inserting a fixing pin into the pin hole to form the worm shaft. And a connection step of connecting the torsion bar, and in the hole processing step,
A pin hole having a diameter equal to or larger than the diameter of the temporary fixing screw hole is formed, while the direction of action of the force by the cutting tool coincides with the axis of the temporary fixing screw.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 3 showing an embodiment are sectional views of a portion where a fixing pin 35 is inserted into a worm shaft 7. FIG. All other structures are the same as before,
The same components are denoted by the same reference numerals as in the related art, and detailed description thereof is omitted.

The worm shaft 7 is provided with a temporary fixing screw hole 36 penetrating to the hollow portion 6 in the radial direction. Then, a temporary fixing screw 37 is screwed into the temporary fixing screw hole 36 to temporarily fix the torsion bar 9. In this temporary fixing state, the torsion bar 9 is pressed against the pressure contact point a of the hollow portion 6 by the temporary fixing screw 37. After the torsion bar 9 is pressed against the pressure contact a in this way, the pin holes 39, 4 are cut in a direction opposite to the direction in which the pressing force acts, that is, in the direction of arrow 38 using a cutting tool such as a drill.
0 is drilled. At this time, the force of the cutting tool in the direction of the arrow 38 acts so as to coincide with the axis of the temporary screw 37.

Since the acting direction of the force of the cutting tool coincides with the axis of the temporary fixing screw 37 as described above, even if the force acts on the worm shaft 7 and the torsion bar 9, both of them are applied. The relative position does not shift.
Moreover, even after the cutting tool has penetrated the torsion bar 9, the tip of the cutting tool cuts the screw 37 along the axis of the temporary fixing screw 37.
After cutting through, the tip of the cutting tool does not run out. Since the tip of the cutting tool does not swing in this way, the pin hole 39
Will be formed with their axes accurate.

The diameter D of the pin holes 39 and 40 formed as described above is larger than the diameter d of the temporary screw hole 36. The reason for increasing the diameter D in this way is to completely remove the temporary fixing screw 37 screwed into the temporary fixing screw hole 36 in the cutting process. If the temporary fixing screw 37 is scraped off in the cutting process as described above, it takes a lot of time to remove the temporary fixing screw 37 after the cutting. Therefore, the diameter D of the pin holes 39 and 40 is the
6 or more.
By setting the diameter to be D ≧ d (the diameter of the temporary fixing screw hole 36), the temporary fixing screw 37 can be scraped off in the cutting process.

Further, since the pin hole 39 is formed in the place where the temporary fixing screw hole 36 is located, the temporary fixing screw holes 27 and 28 other than the pin hole 33 do not remain in the worm shaft 7 as in the related art. If the temporarily-fixed screw holes 27 and 28 remain as in the conventional case, the thickness of the portion is lost, and the strength is inevitably reduced. However, according to this embodiment, the strength of the worm shaft 7 does not decrease.

The pin holes 39, 4 formed as described above
At 0, a fixing pin 35 having a diameter substantially equal to those of the pin holes 39 and 40 is press-fitted. FIG. 3 shows a state in which the fixing pin 35 is press-fitted into the pin holes 39 and 40. If the fixing pin 35 is press-fitted in this way, the neutral position of the rotary valve V is accurately maintained in advance. Therefore, the relative positions of the worm shaft 7 and the torsion bar 9 are connected while maintaining the neutral state accurately.

The fixing pin 35 to be press-fitted as described above is tapered at the distal end side in the insertion direction and is narrowed. The reason for narrowing the tip in this way is as follows. That is, after the pin holes 39 and 40 are processed, these pin holes 3
When an attempt is made to press-fit the fixing pins 35 into the holes 9 and 40, the worm shaft 7 and the torsion bar 9 may rotate relative to each other for some reason, and the pin holes 39 and 40 may shift. This is because the fixing pin 35 can be press-fitted. If the tip of the fixing pin 35 is made thinner as described above, the tip can be inserted into the pin holes 39 and 40 even if the pin hole 39 and the pin hole 40 are slightly shifted. As long as the tip of the fixing pin 35 can be inserted into the pin hole 40, the fixing pin 35 can be press-fitted. Then, by press-fitting the fixing pin 35, the deviation of the relative rotation between the worm shaft 7 and the torsion bar 9 is also corrected. Therefore, the neutral position is set accurately.

According to the method of the above embodiment, with the torsion bar 9 pressed against the pressure contact point a by one temporary fixing screw 37, the pin hole 39 is cut with a cutting tool or the like from the direction opposite to the direction in which the pressing force acts. , 40 are drilled, and at this time, the force of the cutting tool acting on the worm shaft 7 and the torsion bar 9 is made to coincide with the axis of the temporary screw 37, so that the worm shaft 7 and the torsion bar 9 are drilled. Relative position does not shift.
In other words, the position of the worm shaft 7 and the position of the torsion bar 9 do not shift regardless of what strong force is applied during drilling. Therefore, even if there is only one temporary fixing screw hole 36 and one temporary fixing screw 37, the torsion bar 9 at the time of assembling is used.
Can be prevented from shifting. In addition, since only one temporary fixing screw hole 36 and one temporary fixing screw 37 are required, the processing cost and the assembly operation cost can be reduced.

Further, when the pin holes 39 and 40 are machined, the temporary fixing screw 37 is also removed together with the temporary fixing screw hole 36, so it is necessary to remove the temporary fixing screw 37 after assembling the fixing pin 35. Nor. As described above, since it is not necessary to remove the temporary fixing screw 37, the assembling workability is further improved. In this embodiment, the fixing pin 35 is press-fitted into the pin holes 39 and 40.
A fixing pin 35 having a diameter slightly smaller than that of the fixing pins 9 and 40 may be inserted into the pin holes 39 and 40, and the fixing pins 35 may be fixed to the pin holes 39 and 40 with an adhesive or the like.

[0023]

According to the present invention, after the torsion bar is pressed against one side of the worm shaft with the temporary fixing screw and temporarily fixed, the working direction of the pressing force of the temporary fixing screw is applied to the worm shaft and the torsion bar. Drilling of a pin hole is performed from the opposite direction. In this drilling, the direction of the force applied by the cutting tool is made to coincide with the axis of the temporary fixing screw. For this reason, the position of the torsion bar does not shift with respect to the worm shaft regardless of what kind of strong force is applied during the processing of the pin hole. Therefore, if the neutral position between the torsion bar and the worm shaft is accurately set at the time of the temporary fixing, the fixing pin is inserted into the pin hole, and the torsion bar and the worm shaft are maintained in a state where the neutral position of the rotary valve is accurately maintained. It can be connected to a shaft.

When assembling the torsion bar and the worm shaft in this manner, if only one temporary fixing screw and one temporary fixing screw hole are required, two temporary fixing screws and two temporary fixing screw holes are required. Parts costs, machining costs and assembling work costs can be reduced as compared with the conventional assembling direction. In addition, since the diameter of the pin hole is set to be equal to or larger than the diameter of the temporary fixing screw hole, the temporary fixing screw together with the temporary fixing screw hole can be removed when the pin hole is formed. Therefore, after the torsion bar and the worm shaft are assembled, it is not necessary to remove the temporary fixing screw. Therefore, the assembling work cost can be further reduced. Further, since the pin hole is formed at the place where the temporary fixing screw hole was, no temporary fixing screw hole remains except the pin hole as in the related art. Therefore, it is possible to prevent a decrease in the strength of the worm shaft due to the temporary screw holes.

[Brief description of the drawings]

FIG. 1 is a sectional view of an apparatus according to an embodiment, showing a state in which a worm shaft 7 and a torsion bar 9 are temporarily fixed with a temporary fixing screw 37. FIG.

FIG. 2 is a sectional view of the device of the embodiment, showing pin holes 39, 4 penetrating through the worm shaft 7 and the torsion bar 9;
It is a figure which shows the state which processed 0.

FIG. 3 is a view showing a state in which a fixing pin 35 is pressed into pin holes 39 and 40;

FIG. 4 is a cross-sectional view of the power steering device.

FIG. 5 is a sectional view of a portion showing a connection state between the stub shaft 5 and the worm shaft 7;

FIG. 6 is a sectional view of a portion where the worm shaft 7 and the torsion bar 9 are fixed with the fixing pin 11.

[Description of Signs] 2 Rotary pool 3 Valve sleeve 5 Stub shaft 6 Hollow portion 7 Worm shaft 9 Torsion bar 35 Fixing pin 36 Temporary fixing screw hole 37 Temporary fixing screw 39 Pin hole 40 Pin hole V Rotary valve

Claims (1)

[Claims] 1. A rotary valve comprising: a rotary pool which rotates integrally with a stub shaft; and a valve sleeve which rotates relative to the rotary pool and rotates integrally with a hollow worm shaft. After fixing the torsion bar, the other end of the torsion bar is fixed to the worm shaft with a fixing pin penetrating through the hollow portion of the worm shaft. A temporary fixing step of pressing the torsion bar against one side of the worm shaft with a temporary fixing screw protruding from the temporary fixing screw hole into the hollow portion of the worm shaft, and a direction opposite to a direction in which the pressing force of the temporary fixing screw acts. From the worm shaft and torsion bar A hole forming step of forming a hole, and a connecting step of connecting a worm shaft and a torsion bar by inserting a fixing pin into the pin hole, wherein in the hole forming step, the action direction of a force by a cutting tool is temporarily fixed. A method for assembling a power steering device, wherein a pin hole having a diameter equal to or greater than the diameter of the temporary screw hole is formed while being aligned with the axis of the screw.