JPH1134896A - Power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an input shaft with a preset force despite of a simple constitution. SOLUTION: A first pin 33 is fixed to one end 31 of a torsion bar 3 and a second pin 34 is fixed to the other end 32. A first through hole 22 in which the first pin is inserted relatively rotationally in relation to an input shaft 2 and a second through hole 23 in which the second pin is inserted relatively rotationally in relation to the input shaft are formed in the input shaft 2. A first recess part 43 in which the first pin is inserted relatively rotationally in relation to an output shaft and a second recess part 44 in which the second pin is inserted relatively rotationally in relation to the output shaft are formed in the output shaft 4. The torsion bar 3 is assembled between the input and output shafts in a twisted state so that its one end 31 energizes the input and output shafts in one direction of the rotation direction through the first pin and the input and output shafts are energized in the other direction of the rotation direction through the second pin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering apparatus having a torsion bar for connecting an input shaft and an output shaft so as to be relatively rotatable.

[0002]

2. Description of the Related Art Conventionally, as this kind of technique, for example, a technique disclosed in Japanese Utility Model Publication No. 7-2356 is known. This includes an input shaft that is rotated by operating a steering wheel, an output shaft coaxially arranged with the input shaft, a torsion bar that connects the input shaft and the output shaft so as to be relatively rotatable, and an output shaft and a wheel. And a steering assist device that generates a steering assist force according to a relative rotation amount of the input shaft with respect to the output shaft to steer the wheels. Here, one end of the torsion bar is connected to the input shaft via a first pin, and the other end is connected to the output shaft via a second pin.

Further, a hydraulic reaction force device is provided to restrain relative rotation between the input shaft and the output shaft in the initial state (ie, to apply a predetermined preset force to the input shaft). This is a reaction force receiving portion provided integrally with the input shaft and having a concave portion, a flange portion provided integrally with the output shaft to face the reaction force receiving portion and having a guide hole, and inserted into the guide hole. And a reaction pinion that receives hydraulic pressure and thereby presses the ball against the concave portion of the reaction force receiving portion.

[0004]

However, in this case, as described above, in order to provide a preset force,
Since at least the ball and a reaction force piston for pressing the ball toward the input shaft are indispensable, the number of parts increases correspondingly, which is disadvantageous in cost. In addition, hydraulic pressure is required to act on the reaction force piston, and as a result, a hydraulic supply source and a supply passage are required, resulting in a further disadvantageous configuration in terms of cost.

Therefore, an object of the present invention is to apply a preset force to an input shaft with a simple configuration.

[0006]

According to a first aspect of the present invention, there is provided a power steering apparatus comprising: an input shaft which is rotated by operating a steering wheel; An output shaft, a torsion bar that connects the input shaft and the output shaft so as to be relatively rotatable, and a torsion bar that is connected between the output shaft and the wheels, according to a relative rotation amount of the input shaft with respect to the output shaft. A steering assist device that generates a steering assist force and steers the wheels, wherein the input shaft is arranged around the torsion bar, the output shaft is arranged around the input shaft, and one end of the torsion bar is provided. A first engagement member is fixed, and a second engagement member is fixed to the other end, and the input shaft is rotatable with respect to the input shaft in a circumferential direction of the input shaft. First to insert
A through-hole, a second through-hole for inserting the second engagement member in a circumferential direction of the input shaft so as to be relatively rotatable with respect to the input shaft, and forming the first engagement member on the output shaft; And a first concave portion for inserting the second engagement member in the circumferential direction of the output shaft so as to be relatively rotatable with respect to the output shaft, and inserting the second engagement member in a circumferential direction of the output shaft so as to be relatively rotatable with respect to the output shaft. And a second concave portion that urges the input shaft and the output shaft in one direction of rotation through the first engagement member, and urges the input shaft and the output shaft through the second engagement member. The input shaft and the output shaft are assembled between the input and output shafts in a twisted state so as to bias the input shaft and the output shaft in the other direction of rotation. That is, the torsion bar in a twisted state urges the first engagement member in the direction opposite to the torsion direction of one end of the torsion bar, and the second engagement member opposes the torsion direction of the other end of the torsion bar. Biased in the direction. That is, the first and second engagement members are urged in directions opposite to each other.

The operation of the invention of claim 1 will be described below.

When the input shaft is rotated in the torsion direction of one end of the torsion bar (hereinafter, referred to as a first direction), the input shaft is rotated by the one end of the torsion bar through the first engagement member in a direction opposite to the first direction. That is, the direction against the rotation direction)
It is urged to. At this time, the output shaft is urged by the other end of the torsion bar in the direction opposite to the torsion direction of the other end of the torsion bar (ie, the first direction) via the second engagement member. Even if the rotational torque is transmitted to the other end of the torsion bar via the first engagement member and one end of the torsion bar, the other end (the second engagement member) of the torsion bar is turned in the opposite direction to the torsion direction (the first direction). Direction). Therefore, a preset force according to the torsion bar torsion state is reliably applied to the input shaft.

When the rotation torque of the input shaft exceeds the predetermined preset force, the input shaft further twists one end of the torsion bar via the first engagement member, and moves relative to the output shaft in the first direction. Rotate. As a result, a steering assist force is generated by the steering assist device in accordance with the relative rotation amount, and the wheels are steered in one direction.

On the other hand, when the input shaft is rotated in the torsion direction of the other end of the torsion bar (hereinafter referred to as the second direction), the input shaft is connected to the second direction by the other end of the torsion bar via the second engaging member. Are biased in the opposite direction (i.e., in the direction opposite to the direction of rotation). At this time, since the output shaft is urged by the one end of the torsion bar through the first engagement member in the direction opposite to the torsion direction of the one end of the torsion bar (that is, in the second direction), the rotational torque of the input shaft is increased. Is transmitted to one end of the torsion bar via the second engagement member and the other end of the torsion bar, the one end of the torsion bar is prevented from rotating in the direction opposite to the twisting direction. Therefore, a preset force according to the torsion bar torsion state is reliably applied to the input shaft.

When the rotational torque of the input shaft exceeds the predetermined preset force, the input shaft further twists the other end of the torsion bar through the second engagement member, and moves in the second direction with respect to the output shaft. Relative rotation. As a result, a steering assist force is generated by the steering assist device in accordance with the relative rotation amount, and the wheels are steered in the other direction.

As described above, with a simple configuration, a preset force can be applied to the input shaft.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A power steering apparatus according to the present embodiment will be described below with reference to the accompanying drawings.

(First Embodiment) As shown in FIG. 1, the power steering device 1 has a first housing 10 and a second housing 11, both of which are fixed. The input shaft 2 is rotatably supported in the first housing 10 and is configured to rotate by operating a steering wheel (not shown) of the vehicle. Input shaft 2 is torsion bar 3
Is connected to an output shaft 4 arranged coaxially with the input shaft 2 so as to be relatively rotatable.

In the second housing 11, a power cylinder 5 for assisting a steering operation force to steer wheels of the vehicle is provided. The power cylinder 5 has a cylinder 51, a piston 52 slidably disposed on the cylinder 51, and two pressure chambers 53 and 54 formed by the piston 52. A rack 55 is formed on a part of the outer peripheral portion of the piston 52, and the sector gear 6 interlocking with the wheels meshes with the rack 55. Therefore, the sector gear 6 is rotated by the reciprocating motion of the piston 52.

An insertion hole 56 is formed in the piston 52 on the same axis as the output shaft 4.
The spiral worm 41 formed on the left side of FIG. A spiral ball screw groove 57 is formed in the insertion hole 56, and a ball 58 is disposed in the ball screw groove 57. The worm 41 is connected to the piston 5 via a ball 58.
2 is engaged with the second insertion hole 56. Therefore, the rotational movement of the output shaft 4 is converted into a linear movement of the piston 52. still,
The right end of the piston 52 in the figure is closed by a stopper 59.

In the first housing 10, input / output shafts 2,
4 based on the relative rotation amount of the pressure cylinder 5 of the power cylinder 5.
3, 54 are provided with rotary valves 7 for controlling the supply and discharge of pressure fluid. The rotary valve 7 has the input shaft 2
An inner valve 71 provided integrally with the outer peripheral portion of the first valve and an outer valve 72 disposed around the inner valve 71. The outer valve 72 is integrally rotatably connected to the output shaft 4 via the pin 8 and is arranged coaxially with the input / output shafts 2 and 4.

The rotary valve 7 is normally located at a first position (non-operating position) that connects the first and second pressure chambers 53 and 54 to a reservoir (not shown). When the input shaft 2 rotates relative to the output shaft 4 in one direction, the inner valve 71 also rotates relative to the outer valve 72 in the same direction, and the rotary valve 7 moves the first pressure chamber 53 only to a hydraulic pump (not shown). The position is switched to a second position (first operating position) in which the communication and the second pressure chamber 54 communicate only with the reservoir. Then, since the volume of the first pressure chamber 53 of the power cylinder 5 is increased, the piston 52 moves leftward in the drawing, and the wheels are steered in one direction. On the other hand, when the input shaft 2 rotates relative to the output shaft 4 in the other direction, the inner valve 71 also rotates relative to the outer valve 72 in the same direction, and the rotary valve 7 rotates.
Is switched to a third position (second operating position) in which the first pressure chamber 53 communicates only with the reservoir and the second pressure chamber 54 communicates only with the hydraulic pump. Then, since the volume of the second pressure chamber 54 of the power cylinder 5 is increased, the piston 52 moves rightward in the drawing, and the wheels are steered in the other direction. Here, the force acting on the piston 52 due to the differential pressure between the first and second pressure chambers 53 and 54 becomes the steering assist force.

Hereinafter, the main part of the first embodiment will be described.

As shown in FIG. 1, the output shaft 4 has a cavity 42.
Is formed, and the input shaft 2 is disposed in the cavity 42.
A cavity 21 is formed in the input shaft 2, and the torsion bar 3 is arranged inside the cavity 21. Torsion bar 3
A first pin (first engaging member) 33 is press-fitted and fixed to one end (right end in the drawing), and a second pin (second engaging member) 34 is press-fitted and fixed to the other end (left end in the drawing). ing.

As shown in FIG. 2, two first inner through holes 22 are formed at one end of the input shaft 2 in the circumferential direction.
The first pin 33 is inserted into the first inner through holes 22, 22 so as to be rotatable relative to the input shaft 2 in the circumferential direction of the input shaft 2. Also,
One end of the output shaft 4 has a first inner through hole 2 in an initial state.
2, two first outer through holes (first concave portions) 43, 43 are formed. The first pins 33 are also inserted into the first outer through holes 43 and 43 so as to be rotatable relative to the output shaft 4 in the circumferential direction of the output shaft 4.

As shown in FIG. 3, two second inner through holes 23 are formed in the other end of the input shaft 2 in the circumferential direction.
The second pin 34 is inserted into the second inner through holes 23, 23 so as to be rotatable relative to the input shaft 2 in the circumferential direction of the input shaft 2. The second inner through-hole 23 is connected to the first inner through-hole 22 by the input shaft 2.
Are shifted by a predetermined angle in the circumferential direction. The other end of the output shaft 4 is provided with two second outer through holes (second concave portions) 4 so as to face the second inner through holes 23 in the initial state.
4, 44 are formed. These second outer through holes 4
The second pins 34 are also inserted into the output shafts 4 and 44 so as to be rotatable relative to the output shaft 4 in the circumferential direction of the output shaft 4. The second outer through hole 44 is also shifted by a predetermined angle in the circumferential direction of the output shaft 4 with respect to the first outer through holes 43.

The torsion bar 3 is assembled between the input shaft 2 and the output shaft 4 in a twisted state. That is, one end 31 of the torsion bar 3 is twisted in the direction of FIG. 2A (counterclockwise), and the other end 32 is twisted in the direction of FIG. 3B (clockwise). That is, the first pin 33 is urged by the torsion bar 3 in the direction opposite to the direction A, and the second pin 34 is urged in the direction opposite to the direction B. Thereby, the first pin 33 is connected to the first inner through hole 22 and the first
The second pin 34 is pressed against the A-side end surfaces of the second inner through-hole 23 and the second outer through-hole 44 while being pressed against the B-direction end surface of the outer through-hole 43. In other words, one end 31 of the torsion bar 3 moves the input shaft 2 and the output shaft 4 via the first pin 33 in the direction opposite to the direction A (that is, in the direction B).
Direction) and the other end 32 of the torsion bar 3.
Are configured to urge the input shaft 2 and the output shaft 4 via the second pin 34 in the direction opposite to the direction B (ie, the direction A).

The first and second outer through holes 4 of the output shaft 4
The grooves 3 and 44 need not be limited to through holes, but may be provided with grooves extending in the axial direction, for example. Further, the inner through holes 22 and 23 and the outer through holes 43 and 44 are provided two each, but one or three or more may be provided.

The operation of the power steering device 1 will be described.

When the driver rotates the steering wheel in one direction to rotate the input shaft 2 in the direction of FIG. 2A (that is, the torsion direction of one end of the torsion bar), the input shaft 2 is moved by one end 31 of the torsion bar 3. It is urged through the first pin 33 in the direction opposite to the direction A (that is, the direction shown in FIG. 3B).

At this time, the second pin 34 is pressed against the end surface of the second outer through hole 44 of the output shaft 4 in the direction A by the urging force of the other end 32 of the torsion bar 3.
Is transmitted to the other end 32 of the torsion bar 3 via the first pin 33 and the one end 31 of the torsion bar 3, the second pin 34 and the other end 32 of the torsion bar 3
Is prevented from rotating in the direction A (that is, in the direction opposite to the torsion direction of the other end 32 of the torsion bar).

As described above, as shown in FIG. 4, a predetermined preset force Tp1 based on the torsion state of the torsion bar 3 is reliably applied to the input shaft 2.

When the rotational torque TM of the input shaft 2 exceeds the preset force Tp1, the input shaft 2 further twists the one end 31 of the torsion bar 3 via the first pin 33, and the input shaft 2 Rotate relatively. That is, the first pin 3
3 is separated from the end surface of the first outer through hole 43 on the B direction side. As a result, as described above, a steering assist force is generated according to the relative rotation amount between the input and output shafts, and the wheels are steered in one direction. At this time, as shown in FIG. 4, as the rotation angle of the input shaft 2 (the amount of relative rotation between the input and output shafts) increases, the input torque increases.

When the first pin 33 comes into contact with the end surface of the first outer through hole 43 in the direction A, the input shaft 2 and the output shaft 4 rotate integrally. Here, the first pin 33 contacts the A-direction end surface of the first outer through-hole 43 before the B-direction end surface of the second inner through-hole 23 contacts the second pin 34. Therefore, the first
The diameter of the first pin 33 is larger than the diameter of the second pin 34 so that the first pin 33 does not break when the pin 33 abuts.

On the other hand, when the driver rotates the steering wheel in the other direction to rotate the input shaft 2 in the direction of FIG. 3B (that is, the torsion direction of the other end 32 of the torsion bar 3), Accordingly, the input shaft 2 is urged via the second pin 34 in the direction opposite to the direction B (ie, the direction A).

At this time, the first pin 33 is pressed against the B-direction end surface of the first outer through hole 43 of the output shaft 4 by the urging force of the one end 31 of the torsion bar 3.
Is transmitted to the one end 31 of the torsion bar 3 via the second pin 34 and the other end 32 of the torsion bar 3, the first pin 33 and the one end 31 of the torsion bar 3
Is prevented from rotating in the direction B (that is, the direction opposite to the twisting direction of the one end 31 of the torsion bar).

As described above, as shown in FIG. 4, a predetermined preset force Tp2 based on the torsion state of the torsion bar 3 is reliably applied to the input shaft 2.

When the rotation torque TM of the input shaft 2 exceeds the preset force Tp2, the input shaft 2 further twists the other end 32 of the torsion bar 3 via the second pin 34, and the output shaft 4 in the B direction. Rotate relative to. That is, the second pin 3
4 is separated from the end surface on the A direction side of the second outer through hole 44. As a result, as described above, a steering assist force is generated according to the relative rotation amount between the input and output shafts, and the wheels are steered in the other direction. Also at this time, as shown in FIG.
As the (relative rotation amount between the input and output shafts) increases, the input torque TM increases.

When the end surface of the input shaft 2 on the side of the first inner through hole 22 in the direction A contacts the first pin 33, the input shaft 2 and the output shaft 4 rotate integrally.

FIG. 4 also shows the relationship between the rotation angle θM of the input shaft and the input torque TM of the technique in which the torsion bar is assembled without twisting, as is apparent from FIG.
No preset power is given.

(Second Embodiment) As shown in FIGS. 5 and 6, in the power steering device of the second embodiment, one end 31 of the torsion bar 3 is connected to the input shaft 2 via the first pin 330.
The only difference from the first embodiment is that the outer valve 72 that rotates integrally with the output shaft 4 is urged in the direction opposite to the twisting direction. Therefore, the operation is substantially the same.

In the first aspect, it is described that "one end of the torsion bar urges the input shaft and the output shaft via the first engagement member in the direction opposite to the torsion direction."
The output shaft mentioned here also includes the outer valve.

[0039]

According to the first aspect of the invention, since the torsion bar is assembled between the input and output shafts in a twisted state, a preset force based on the torsion state of the torsion bar can be applied to the input shaft. As described above, since the preset force can be applied using the existing torsion bar, the number of parts can be reduced correspondingly, which is advantageous in cost.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a power steering device according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line AA of FIG.

FIG. 3 is an enlarged sectional view taken along line BB of FIG. 1;

FIG. 4 is a graph showing a relationship between an input angle and an input torque of the power steering device according to the first embodiment.

FIG. 5 is an enlarged sectional view of a main part of a power steering device according to a second embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view taken along the line CC of FIG. 5;

FIG. 7 is an enlarged sectional view taken along the line DD of FIG. 5;

[Explanation of symbols]

 Reference Signs List 1 power steering device 2 input shaft 22 first inner through hole (first through hole) 23 second inner through hole (second through hole) 3 torsion bar 31 one end of torsion bar 32 other end of torsion bar 33 first pin (1st engaging member) 34 2nd pin (2nd engaging member) 4 Output shaft 43 1st outside through-hole (1st recess) 44 2nd outside through-hole (2nd recess) 5 Power cylinder (steering assistance device) 7) Rotary valve (steering assist device)

Claims (1)

[Claims] An input shaft that is rotated by operating a steering wheel; an output shaft coaxially arranged with the input shaft; a torsion bar that connects the input shaft and the output shaft so as to be relatively rotatable; A power steering device that is connected between an output shaft and wheels and includes a steering assist device that generates a steering assist force according to a relative rotation amount of the input shaft with respect to the output shaft and steers wheels. The output shaft is disposed around the input shaft, the first engagement member is fixed to one end of the torsion bar,
A second engagement member fixed to the other end; the input shaft, a first through hole for inserting the first engagement member in a circumferential direction of the input shaft so as to be relatively rotatable with respect to the input shaft; A second through-hole for inserting a second engaging member in a circumferential direction of the input shaft so as to be relatively rotatable with respect to the input shaft; and the output shaft is configured to connect the first engaging member to the output shaft. A first recess inserted to be rotatable relative to the output shaft in a circumferential direction, and a second recess inserted to be rotatable relative to the output shaft in a circumferential direction of the output shaft, the second engagement member. The torsion bar urges the input shaft and the output shaft in one direction of rotation via the first engagement member, and the input shaft and the output shaft via the second engagement member. The output shaft is assembled between the input and output shafts in a twisted state so as to urge the output shaft in the other direction of rotation. Power steering apparatus are.