JPH11278291A - Power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power steering device having a steering rod which can be corrected in a short time from a bent state produced by heat treatment. SOLUTION: A torque detection mechanism for detecting steering torque and an assisting mechanism which imparts an assisting force to a steering rod are linked with the steering rod via transmission means such as screws and gears, and of the transmission means constituting the torque detection means, the screws or gears formed at the steering rod are made to differ in cross-sectional shape from the screws or gears formed at the steering rod, among the transmission means constituting the assisting mechanism. Thus, the steering rod is divided into a first rod part 20 where the screw or gears for the torque detection mechanism are formed and a second rod part 22 where the screws or gears for the assisting mechanism are formed, and the rods parts are connected together via connections provided at the rod parts.

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 in which a steering wheel and a steering mechanism for applying an assist force are linked to a steering rod for steering a steered wheel.

[0002]

2. Description of the Related Art In the conventional apparatus shown in FIGS. 11 and 12, a steering rod 2 is inserted into a case 1. FIG. The steering rod 2 is configured to be movable in the axial direction, but the rotation thereof is restricted. The steering rod 2 thus configured is provided with link members 41 at both ends thereof, and is linked to steered wheels (not shown) via the link members 41. A torque detecting mechanism is provided on one side of the steering rod 2. The torque detecting mechanism includes a rack 3 formed on the steering rod 2, a pinion 4 meshing with the rack 3, and a pinion 4. And a torque sensor 5 linked to the torque sensor 4. The torque sensor 5 detects a steering reaction force when the steering wheel (not shown) is turned, and outputs a detection signal to a controller (not shown). Then, the controller receiving this output signal controls the output of the electric motor M described later.

An assist mechanism is provided on the left side of the case 1 in the drawing, that is, on the side opposite to the rack 3. The assist mechanism includes an electric motor M, and a cover 7 of the electric motor M is fixed to the case 1 by bolts B. The stator 8 of the electric motor M
Is fixed to the cover side 7, and the rotors 9, 9 are connected to the output shaft 1.
It is fixed to the 0 side. The output shaft 10 has a cylindrical shape, and the turning rod 2 is movably inserted therein. On the left side of the output shaft 10 in the drawing, an enlarged diameter portion 10a is formed as shown in FIG. 12, and a step portion is formed at an inner end of the enlarged diameter portion 10a.
The rotating member 11 is inserted into the enlarged diameter portion 10a as described above, and the rotating member 11 is sandwiched between the nut 19 fitted from the outside of the enlarged diameter portion 10a and the stepped portion, and the output member is rotated. It is configured to rotate integrally with the shaft 10.

A ball screw groove 6a is formed on the inner periphery of the rotating member 11 which rotates integrally with the output shaft 10. On the other hand, a ball screw groove 6b is also formed on the surface of the steering rod 2, and a ball r is interposed between the ball screw grooves 6a and 6b. A step 10b is formed on the outer periphery of the output shaft 10 on the right side in the figure, and bearings 13 and 14 are provided on the right side in the figure with respect to the step 10b. A nut 15 is provided on the right side of the bearing 13, and the bearings 13 and 14 are fixed to the output shaft 10 between the nut 15 and the step 11b.

On the other hand, a nut 16 is provided on the left side of the bearing 13 so as to fit into the case 1, and the bearings 13 and 14 are interposed between the nut 16 and the step 17 of the case 1, so that the output shaft 10 with respect to the case 1 is formed. In the axial direction. The output shaft 10
A bearing 18 is also provided on the outer periphery of the enlarged diameter portion 10a. The bearing 18 and the bearing 1
The output shaft 10 is rotatably supported with respect to the case 1 by 3 and 14.

[0006] As described above, the output shaft 10 is rotatably supported while its movement in the axial direction is restricted, and the steering rod 2 is supported in a state where it is movable in the axial direction and the rotation thereof is prevented. When the output shaft 10 rotates, the torque of the rotating member 11 is transmitted to the steering rod 2 via the ball screw, and the torque is transmitted to the steering rod 2.
Is converted to an axial moving force. Therefore, when the steering wheel (not shown) is turned, the torque sensor 5 detects the steering torque, and this detection signal is input to a controller (not shown). The controller operates the electric motor M based on the signal, rotates the output shaft 10, moves the steered rod 2 in the axial direction, and steers steered wheels (not shown).

[0007]

In the above-mentioned conventional apparatus,
The rack 3 and the ball screw groove 6b are formed on one steering rod 2. These racks 3 and ball screw grooves 6b
After being processed, it is subjected to a heat treatment to harden its surface. When the heat treatment is performed in this manner, the rack 3 and the ball screw groove 6b are bent. Therefore, after the heat treatment, the steering rod 2 is straightened by correcting the bending.

However, the rack 3 and the ball screw groove 6b
Since the section has a different cross-sectional shape, the degree of bending when heat-treated is different. It was very difficult to correct a single rod having a different bending state. For example, if the bending on the ball screw groove 6b side is corrected after correcting the bending on the rack 3 side, the force for correcting the ball screw groove 6b side also affects the rack 3 side. For this reason, the rack 3 side previously corrected may bend, and the rack 3 side may have to be corrected again. Further, when the rack 3 is corrected again, the ball screw groove 6b may be bent this time due to the influence. As described above, since the correction work has to be performed many times, there is a problem that the correction work takes time. SUMMARY OF THE INVENTION An object of the present invention is to provide a power steering device provided with a steering rod capable of correcting bending caused by heat treatment in a short time.

[0009]

According to the present invention, there is provided a steering rod having steering wheels linked to both ends thereof, and a torque detecting means for linking the steering rod via a transmission means such as a screw or gear to detect a steering torque. A steering mechanism, and an assist mechanism that is linked to the steering rod via a transmission means such as a screw or a gear to apply an assist force to the steering rod. And a power steering device in which the cross-sectional shape of the screw or gear formed on the steering rod is different from that of the transmission means constituting the assist mechanism.

The first invention is based on the premise of the above-mentioned device. The first invention is characterized in that the steering rod comprises a first rod portion formed with a screw or gear on the torque detecting mechanism side and a second rod portion formed with a screw or gear on the assist mechanism side. It is characterized in that it is divided into two rod parts and these two rod parts are connected via connecting parts provided respectively. According to a second aspect of the present invention, the torque detection mechanism includes a rack formed on the first rod portion, and a pinion provided on the torque sensor side.
An electric motor having a rotating member provided around the steering rod, a screw groove formed on the inner periphery of the rotating member, a screw groove formed on the steering rod, and a ball interposed between the two screw grooves. It is characterized by points.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus according to an embodiment of the present invention will be described with reference to FIGS. However, since the configuration other than the steering rod is the same as that of the above-described conventional example, the following description focuses on the steering rod, and the same reference numerals are given to the same components as those in the related art, and detailed description thereof will be omitted.

The first embodiment shown in FIGS. 1 (a), 1 (b) and 2 shows a first rod portion 20 and a second rod portion 22 which constitute a steered rod. The part 20 has a rack 21 which is an element of the torque detecting mechanism, and the second rod part 22 has a ball screw groove 23 which is an element of the assist mechanism. Further, a female screw portion 24 is formed in the axial direction on the left side of the first rod portion 20 in the drawing, and a male screw portion 25 is formed on the right side of the second rod portion 22 in the drawing. Are fitted to connect the first rod portion 20 and the second rod portion 22. Therefore, these two screw portions 24 and 25 constitute the connecting portion of the present invention.

As shown in FIG. 2, the female thread 24 of the first rod 20 is connected to the male thread 25 of the second rod 22.
To fit. After the screw portions 24 and 25 are fitted in this way, a radial through hole 26 is opened in the rod portion of the fitted portion, and the pin p is inserted into the through hole 26. In this way, both rod portions 20, 22 can be connected in a state where relative rotation is prevented. In the first embodiment, the female thread 24 is formed on the first rod 20 and the male thread 25 is formed on the second rod 22. However, the male thread is formed on the first rod 20. Alternatively, a female screw portion may be formed on the second rod portion 22. Also,
The two rod portions 20 and 22 are connected to the female screw portion 24 and the male screw portion 25.
However, they may be connected by press-fitting without forming these screw portions.

In the first embodiment, since the rack 21 is formed on the first rod portion 20 and the ball screw groove 23 is formed on the second rod portion 22, the rack 21 and the ball screw are formed as described above. Since the grooves 23 are formed in separate rods, they can be separately heat-treated. Therefore, even if the rod is bent during the heat treatment, the bending can be corrected independently for each rod. In other words, when correcting the bend of the first rod portion 20, the second
There is no adverse effect on the rod portion 22 side. Therefore, the rod portions 20 and 22 need only correct the bending separately and connect the corrected portions. Therefore, each rod portion needs to be corrected only once, and the work time required for the correction can be reduced as compared with the related art.

Further, the first rod portion 20 is provided with the first rod portion 2.
At 0, the second rod portion 22 is the second rod portion 22 and its degree of bending is substantially constant. Therefore, considering the rod unit, the same bending state is repeatedly corrected. Repeatedly correcting the same bending condition makes the straightening work easier. In this embodiment, a rack and a pinion are used on the torque detection mechanism side, and a ball screw is used on the assist mechanism side.
The present invention can be applied to all the screws and racks formed on the first rod portion 20 and the second rod portion 22 as long as they have different cross-sectional shapes.

The second to eighth embodiments shown in FIGS. 3 to 10 show another example in which the first rod portion 20 and the second rod portion 22 are connected. In the second embodiment shown in FIG. 3, a concave portion 27 is formed in the male screw portion 25, and after the male screw portion 25 and the female screw portion 24 are screwed together, the outer periphery of the first rod portion 20 is positioned at the position of the concave portion 27. I'm crouching. By doing so, the first rod portion 20 and the second rod portion 22 are formed by the swaged portions.
Can be prevented, and their relative rotation can be regulated. Further, even when the concave portion 27 is located all around the male screw portion 25, the relative movement in the axial direction can be regulated, so that the relative rotation of the rod portions 20, 22 can be prevented in combination with the screw connection.

In the second embodiment, since a part of the first rod portion 20 is caulked, the first rod portion 20 is caulked.
The rod portion 20 must be made of a material that can be easily caulked. Therefore, there is a problem that the material that can be used for the first rod portion 20 is limited. Also, the caulking part cannot be redone over and over again just because the caulking operation failed. Therefore, in the second embodiment in which one end of the first rod portion 20 is swaged, if the swaging operation fails,
There is also a problem that the first rod portion 20 is wasted. Therefore, the third and fourth embodiments shown in FIGS. 4 and 5 have solved these problems.

FIG. 4 shows a third embodiment in which annular recesses 20a, 20a
2a is formed. And these annular concave portions 20a,
A ring-shaped connecting member 28 is inserted into the outer periphery of the connecting member 22a.
It is swaged at the position 2a. In this way, the relative movement of the rods 20 and 22 in the axial direction and the relative rotation thereof are also restricted. On the other hand, in the fourth embodiment shown in FIG. 5, the shape of one end 20b of the first rod portion 20 is made octagonal, and the same octagonal cylindrical connecting member 29 is inserted outside the one end 20b. I have to. Also,
The connecting member 29 has a claw portion 29a protruding in the axial direction.
Are formed. Then, this claw portion 29a is
A plurality of concave portions 22b formed on the outer periphery of the rod portion 22 are swaged. In this way, both rod portions 20,
22 is regulated.

According to the third and fourth embodiments, the relative movement of both rod portions 20, 22 is restricted by the connecting members 28, 29, which are members separate from the rod portions.
The material of the rod portion 20 can be freely selected. Further, even when the caulking operation has failed, the connecting members 28 and 29 may be replaced, so that the first rod portion 20 is not wasted. In addition, the shape of the one end 20b of the first rod portion 20 and the shape of the connecting member in the fourth embodiment are not limited to the octagonal shape, and the polygonal shape can regulate the relative rotation between the rod portions 20 and 22.

In the fifth embodiment shown in FIGS. 6 and 7, the distal end side of the male screw portion 25 in the insertion direction is formed into a cracked shape, and a claw portion 30 is formed at the distal end. Further, an annular groove 31 is formed on the inner periphery of the female screw portion 24 of the first rod portion 20. Then, as shown in FIG. 5, when the male screw portion 25 is screwed into the female screw portion 24, the claw portion 30 is hooked on the annular groove 31. In this way, the first and second rods 20, 22
Relative movement in the axial direction can be restricted. In the fifth embodiment, a pin may be used as a rotation stopper, or an adhesive or the like may be used.

In the sixth embodiment shown in FIG. 8, a connecting groove 32 penetrating in the radial direction is formed in the first rod portion 20, and this connecting groove 32 is formed on the opposite side of the shaft tip. The end portion in the axial direction is an enlarged portion 32a. Further, a connecting projection 33 having the same planar shape as the connecting groove 32 is formed at one end of the second rod 22 on the second rod portion 22, and the connecting protrusion 33 is fitted to the connecting groove 32. ing. When the connecting protrusion 33 is fitted into the connecting groove 32, a through hole 34 is formed in the radial direction, and a pin p is inserted into the through hole 34 to prevent separation and relative rotation of the rod portions 20, 22. doing.

The seventh embodiment shown in FIG. 9 is of a ball joint type and has a spherical support 3 on the first rod portion 20 side.
7, and a ball 38 is provided on the second rod portion 22 side. After the ball 38 is fitted into the spherical receiver 37, a through hole (not shown) is opened, and a pin (not shown) is inserted into the through hole to regulate the relative rotation between the rod portions 20, 22. I have. In the eighth embodiment shown in FIG. 10, a shaft hole 39 is made to pass through the first rod portion 20 in the axial direction, and the small diameter portion 40 of the second rod portion 22 is passed through the shaft hole 39 from one end to the other end. Inserted. A screw hole 42 is formed at the distal end side of the small diameter portion 40, and a linking member 41 linked to the steered wheels is screw-connected to the screw hole 42. With this configuration, the second rod portion 22 does not come off the first rod portion 20. In addition, the small diameter portion 4
0 and the shaft hole 39 may be connected by a screw connection. Also in the eighth embodiment, the relative rotation of the rods 20, 22 may be prevented by an adhesive or a pin.

[0023]

According to the first aspect of the present invention, a transmitting means such as a screw or a gear on the torque detecting mechanism formed on the steering rod is provided.
Even if the cross-sectional shape of the transmission mechanism such as a screw or gear formed on the assist mechanism side is different, the bending that occurs when they are heat-treated can be separately corrected. Therefore, when the rod portion provided with one transmission means is corrected, the other transmission means is not adversely affected unlike the related art. As described above, since the correction work can be performed separately on both transmission means sides, the correction work only needs to be performed once in the unit of the first and second rod portions, and the work time can be reduced. As long as the cross-sectional shape is the same, the degree of bending of the rod portion is the same, so that the straightening work is also easy.

According to the second aspect of the present invention, since the ball screw can be used on the assist mechanism side, the transmission of the force is smooth. However, the use of a ball screw on the assist mechanism side is conventionally known. However, since a rack and a pinion are more suitable on the torque detection mechanism side, if a ball screw is used on the assist mechanism side, two types of grooves, a rack and a ball screw groove, having different cross-sectional shapes are formed on the steered rod. Not get. Even if grooves having different cross-sectional shapes are formed in the steering rod in this manner, in the second invention, the straightening of the bending of the steering rod is simplified, so that while maximizing the advantages of the ball screw, The manufacturing process can also be improved.

[Brief description of the drawings]

FIG. 1 is a view showing a steering rod according to a first embodiment, and FIG.
Is a sectional view showing a first rod part, and (b) is a sectional view showing a second rod part.

FIG. 2 is an enlarged sectional view of a connecting portion between a first rod portion and a second rod portion.

FIG. 3 is an enlarged sectional view of a connection portion between a first rod portion and a second rod portion of the second embodiment.

FIG. 4 is an enlarged sectional view of a connection portion between a first rod portion and a second rod portion of the third embodiment.

FIG. 5 is an enlarged cross-sectional view of a connection portion between a first rod portion and a second rod portion according to a fourth embodiment.

FIG. 6 is an enlarged sectional view of a connecting portion of a first rod portion and a connecting portion of a second rod portion in a fifth embodiment.

FIG. 7 is an enlarged sectional view of a connecting portion according to a fifth embodiment.

FIG. 8 is a partial perspective view of the sixth embodiment with a connecting portion cut off.

FIG. 9 is an enlarged sectional view of a connection portion between a first rod portion and a second rod portion of a seventh embodiment.

FIG. 10 is an enlarged sectional view of a connection portion between a first rod portion and a second rod portion of the eighth embodiment.

FIG. 11 is an overall view of a conventional power steering device.

FIG. 12 is a partially enlarged view of a conventional device.

[Explanation of symbols]

 2 Steering rod 4 Pinion 11 Rotating member 20 First rod part 21 Rack 22 Second rod part 23 Ball screw groove 24 Female screw part constituting connecting part of the present invention 25 Male screw part forming connecting part of the present invention r Ball M electric motor

Claims (2)

[Claims] A steering rod having steering wheels linked to both ends;
The steering rod is linked to the steering rod via a transmission means such as a screw or gear to detect the steering torque. The steering rod is linked to the steering rod via a transmission means such as a screw or gear to assist the steering rod. Equipped with an assist mechanism for applying force,
Among the transmission means constituting the torque detection mechanism, the screw or gear formed on the steering rod and the transmission means constituting the assist mechanism have different cross-sectional shapes from the screw or gear formed on the steering rod. In the power steering device, the steering rod is divided into a first rod portion formed with a screw or gear on the torque detection mechanism side and a second rod portion formed with a screw or gear on the assist mechanism side. A power steering device in which parts are connected via connecting parts provided respectively. 2. A torque detection mechanism comprising a rack formed on a first rod portion, and a pinion provided on a torque sensor side, wherein the assist mechanism comprises: an electric motor having a rotating member provided around a steering rod; 2. The power steering apparatus according to claim 1, comprising a screw groove formed on an inner periphery of the rotating member, a screw groove formed on the steering rod, and a ball interposed between the screw grooves.