JPH11342856A - Power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power steering device in which molding efficiency of a limit plate, which is one of structural elements of a torque limiter and required to have both meshing accuracy with a shaft and surface accuracy for a friction clutch, is improved. SOLUTION: A limit plate 124 inside a torque limiter 122 is formed separately out of a cylindrical part 124A on which a plurality of spline grooves 32 to be meshed with splines 21A formed over the outer circumferential surface of an input shaft 21 in the axial direction of the inner circumferential surface, and of a flange part 124B functioning as a friction clutch in such a way as to be pressed onto the bottom surface side of a limit cover 23, and they are thereby integrally combined with each other by a bush 140.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering device for providing an auxiliary steering force when steering a vehicle such as a four-wheeled vehicle.

[0002]

2. Description of the Related Art As this kind of power steering apparatus, for example, the one shown in FIGS. 7 to 9 has been proposed (unpublished application: Japanese Patent Application No. 9-127665). An output shaft 20 of a driving device (electric motor) 10 and an input shaft 21 connected to a steering device (not shown) of a vehicle or the like are connected via a torque limiter 22. The driving device 10 includes a bracket 11,
It is a known electric motor including a yoke 12, an armature 13, a coil 14, a core 15, a magnet 16, a commutator 17, a brush 18, a bearing 19, and an output shaft 20. The torque limiter 22 includes a limit cover 23 rotatably mounted integrally with the output shaft 20, a limit plate 24 rotatably mounted integrally with the input shaft 21,
This limit plate 24 is connected to the limit cover 23 via a pair of cover disks (friction plates) 25A and 25B.
And a pressing member 26 which is pressed to rotate integrally by the frictional force.

[0003] The output shaft 20 is formed in a stepped shape whose front end protruding from the bracket 11 of the drive device 10 is reduced in diameter by one step toward the front end side, and a large diameter at the rear end side is formed. A number of spline grooves 27 extending in the direction of the axis O of the output shaft 20 are formed on the outer periphery of the portion 20A.
On the other hand, in the present embodiment, the limit cover 23 is formed in a substantially cylindrical shape having a bottom with a lightweight metal material such as aluminum, and a mounting hole is provided at the center of the bottom plate portion 23A along the central axis of the limit cover 23. 23B are formed.
The large-diameter portion 2 of the output shaft 20 is inserted into the mounting hole 23B.
0A is press-fitted so that the limit cover 23
The spline grooves 27 bit into the inner wall of the mounting hole 23B of the limit cover 23, and the small diameter portion 20B of the output shaft 20 projects from the bottom surface 23C of the limit cover 23. It is fixed so as to be coaxial and integrally rotatable.

The cylindrical portion 2 of the limit cover 23
On the inner periphery of the 3D, an annular groove (recess) 28 having the center axis as a center is formed on the opening side. A plurality of engaging recesses 29 extending in the central axis direction are formed at equal intervals in the circumferential direction on the inner periphery of the cylindrical portion 23D, and the bottom surface 23C side of these engaging recesses 29. Are formed so as to penetrate the bottom plate portion 23A.

The limit plate 24 has an annular plate-like flange portion 24B at one end of a cylindrical mounting portion 24A.
The inner periphery of the mounting portion 24A has a multi-stage mounting hole 3 having a large diameter portion 30A on the flange portion 24B side and a small diameter portion 30B on the opposite side.
The cylindrical metal bush (sintered bearing) 31 is press-fitted and attached to the large diameter portion 30A. And this limit plate 24
The small diameter portion 20B of the output shaft 20 protruding from the bottom surface 23C of the limit cover 23 is
1 to be accommodated in the limit cover 23 coaxially with the output shaft 20 and the output shaft 2
It is relatively rotatable around the axis O with respect to the zero and the limit cover 23, and is capable of moving back and forth in the direction of the axis O.

Further, the small-diameter portion 30B of the mounting hole 30 of the limit plate 24 is provided with the limit plate 2
4, a number of spline grooves 32 extending in the direction of the axis O, are formed at equal intervals in the circumferential direction. On the other hand, at the end of the input shaft 21, a number of splines 21A meshing with these spline grooves 32 are formed.
Each of the limit plates 24 is formed so as to extend in the direction of the axis X of the input shaft 21, and the input shaft 21 is inserted into the small-diameter portion 30 </ b> B of the mounting hole 30 by engaging the splines 21 </ b> A with the spline grooves 32. As a result, as described above, the input shaft 21 is rotatable integrally with the input shaft 21 around the axis X, and the input shaft 2
The input shaft 21 is attached to the input shaft 21 so as to be able to advance and retreat with respect to 1.

On the other hand, the pair of cover disks 25A,
25B is formed in a substantially annular plate shape whose outer diameter is large enough to be fitted into the inner periphery of the cylindrical portion 23D of the limit cover 23, and the outer periphery thereof has the engaging recesses 29 ...
Are protrudingly provided. However, these engaging projections 25C are connected to the engaging recesses 29 ...
Is engaged with the cover disks 25A, 25A.
B is accommodated in the limit cover 23 so as to be rotatable integrally with the limit cover 23 and to be able to advance and retreat in the direction of the axis O.

Further, these cover disks 25A, 25A
5B shows a state in which one cover disk 25A is in close contact with the bottom surface 23C of the
And the other cover disk 2
5B is located closer to the opening of the limit cover 23 than the flange 24B of the limit plate 24,
The flange portion 24B is arranged so as to be sandwiched in the axis O direction. The cover disks 25A, 25A
B-shaped facing members 33 formed by compression-molding a mixed material of, for example, fibrous material and phenol resin are adhered to the opposing end surfaces of B so that they can be in close contact with each other. The facing members 33 are formed in a ring body having a rectangular cross section.
Four radial grooves 33 a are provided on the surface in close contact with 4 B, and the depth of the grooves 33 a is approximately half the thickness of the facing material 33. The groove 33a has a function as an escape groove for abrasion powder of the facing material 33. The reason why the facing material 33 is not divided into four by the grooves 33a is that the cover disk 2 can be formed integrally.
This is because attachment to 5A and 25B becomes easy.

A C-ring 34 is fitted in the annular groove 28 formed on the opening side of the limit cover 23 as a ring-shaped member in the present embodiment. Between the other cover disk 25B disposed on the opening side, a disc spring is interposed as the pressing member 26 in a compressed state.

Here, as the C ring 34, for example, a retaining ring for a hole specified in JIS B 2804 or a JIS
A C-shaped retaining ring such as a concentric retaining ring for a hole defined in B 2806 is used, and its inner diameter is smaller than the inner diameter of the cylindrical portion 23D of the limit cover 23 as shown in FIG. By fitting such a C-ring 34 into the annular groove 28 with a slightly reduced diameter,
The elastic member is urged in a direction to expand the diameter and is fixed in the limit cover 23. Further, the disc spring serving as the pressing member 26 is formed in a flat conical shape that can be loosely inserted into the inner periphery of the cylindrical portion 23D of the limit cover 23, and the outer peripheral edge thereof is brought into contact with the C-ring 34 and , The inner peripheral edge of which is in contact with the other cover disk 25B, and the cover disks 25A, 25B and the limit plate 24 are pressed against the bottom surface 23C of the limit cover 23 by a pressing force based on the elasticity of the disc spring. Have been.

However, in the power steering apparatus provided with the torque limiter 22 configured as described above, the pressing member 26 is provided with the annular groove 28 formed in the inner peripheral portion of the limit cover 23 via the C ring 34. The pressing member is supported by a cover that covers the outer periphery of the limit cover (for example, Japanese Patent Laid-Open No. 9-84).
As disclosed in the power steering apparatus of Japanese Patent Application Laid-Open No. 300-300, the outer diameter of the torque limiter 22 does not become larger than the outer diameter of the limit cover 23, and the inertia of the torque limiter 22 can be reduced. Drive device 10 for rotationally driving input / output shafts 20, 21
, The input shaft 21 can quickly follow the rotation of the output shaft 20 during normal steering, and high steering responsiveness can be obtained.

[0012]

By the way, the small diameter portion 30B of the mounting hole 30 of the limit plate 24 has:
As described above, a large number of spline grooves 32 extending in the central axis direction of the limit plate 24 are formed at equal intervals in the circumferential direction, and mesh with the large number of splines 21A formed at the end of the input shaft 21. , Limit plate 24
Are attached to the input shaft 21 so as to be rotatable integrally with the input shaft 21 about the axis X and coaxial with the input shaft 21 and to be able to advance and retreat with respect to the input shaft 21 in the axis X direction.

In other words, in the manufacture of the limit plate 24, a meshing accuracy without play and a strength as a power transmission portion to the outside are required for the meshing connection with the input shaft 21. Since the flange portion 24B of the 24 is a portion that carries out power interruption as a slip clutch (torque limiter), in manufacturing this portion,
Surface accuracy is required to generate the necessary sliding friction force. It is difficult to integrally mold such members requiring different types of precision, and therefore, there is a problem that the molding efficiency is poor and the management items increase in terms of precision and strength requirements. The present invention has been made under such a background, and is a component of a torque limiter, and is a component of a torque limiter, and is required to have both a meshing accuracy with a shaft and a surface accuracy required to function as a friction clutch. It aims to increase efficiency.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and to achieve such an object, the present invention relates to a method of connecting an output shaft of a drive device and an input shaft of a steering device via a torque limiter. In the power steering apparatus, the torque limiter is configured to be rotatable integrally with one of the output shaft and the input shaft, and to be rotatable integrally with the other of the output shaft and the input shaft. A rotating body pressed against the rotating body by means, and a plurality of splines are formed in the axial direction on the other outer peripheral surface of the output shaft and the input shaft. A cylindrical portion formed with a plurality of splines that mesh with splines formed on the other outer circumferential surface of the output shaft and the input shaft in the axial direction of the inner circumferential surface; Is Is characterized by having a flange portion that functions as a friction clutch as separate bodies by. Here, one of the meshed splines is formed as a groove side, and the other is formed as a mountain side.

[0015] In the torque limiter of the power steering device thus configured, a plurality of splines are formed on the inner peripheral surface, and a cylindrical portion into which a shaft having a spline that can mesh with the splines is inserted; Since the flange portions required for the respective components are separate from each other, efficient production in consideration of the formation accuracy required for each portion can be performed. Further, these two members may be formed of different materials. That is, according to the above means, the forming efficiency of the limit plate can be increased, and the manufacturing cost can be reduced.

Further, the cylindrical portion and the flange portion can be connected via, for example, a bush. Alternatively, one end side of the cylindrical portion may be fixed by engaging with the flange portion. In this case, for example, a concave portion sandwiching the flange portion (that is, the plate portion) is formed on the flange portion side of the cylindrical portion, One end side of the cylindrical portion can be caulked to the flange portion and fixed. When one end of the cylindrical portion is directly engaged with the flange portion, the portion extending from the one end of the cylindrical portion to the flange portion is in a state of being pulled out of the tube. May be.

[0017]

FIG. 1 shows a torque limiter (12) of a power steering apparatus according to a first embodiment of the present invention.
It is sectional drawing which shows 2). This torque limiter is an improvement of the torque limiter in the power steering apparatus shown in FIGS. 7 to 9 described above, and the same reference numerals are given to the same parts as those in the above-mentioned drawings, and description thereof will be omitted.

In this embodiment, a limit plate 124 is provided instead of the limit plate 24 shown in FIG. As described above, the limit plate 24
Is an integral type in which an annular plate-shaped flange portion 24B is formed at one end of a cylindrical mounting portion 24A. However, the limit plate 124 according to the present embodiment includes a cylindrical portion 124A corresponding to the mounting portion 24A and a flange. An annular plate-like flange portion 124B corresponding to the portion 24B is connected via a bush 140.

The bush 140 includes a small diameter portion 140A press-fit into the cylindrical portion 124A and a large diameter portion 140B coupled to the flange portion 124B.
An annular fitting portion 140C is formed around the axis of the cylindrical portion 124A (coincident with the central axis X in the figure). Also,
At the center of the flange portion 124B, a mounting hole 124C for mounting to the bush 140 is provided, and at its inner diameter portion, an uneven spline for maintaining a strong connection state with the bush 140 is provided. ing. I have. As a configuration procedure, a bush 140 serving as a lid is swaged in the mounting hole 124C of the flange portion 124B so that an edge of the flange portion on the mounting hole 124C side engages with the annular fitting portion 140C. Cylindrical part 124
Press it into A and fix it. FIG. 2 is a partially broken side view showing a state of the limit plate 124 after the press-fitting, wherein an upper half side is a side view and a lower half side is a cross-sectional view from an alternate long and short dash line AA ′.

Here, on the inner peripheral surface 130 of the cylindrical portion 124A, a number of spline grooves 32 extending in the central axis direction of the limit plate 124, that is, in the direction of the axis O, are formed at equal intervals in the circumferential direction. On the other hand, at the end of the input shaft 21, a number of splines 21A meshing with the spline grooves 32 are formed so as to extend in the direction of the axis X of the input shaft 21, respectively.
4, the input shaft 21 is inserted around the axis X coaxially with the input shaft 21 by being inserted into the cylindrical portion 124A by engaging the splines 21A with the spline grooves 32 as described above. The input shaft 21 is rotatable and freely reciprocates with respect to the input shaft 21 in the axis X direction.
Attached to.

With the above-described structure, the limit plate 124 as the rotating body of the present invention is pressed against the bottom plate side of the limit cover 23 as the rotating body. Incidentally, in the conventional example shown in FIGS.
In the output shaft 120 of the present embodiment, the limit plate 0 is formed in a stepped shape whose front end protruding from the bracket 11 of the drive device 10 is reduced by one step toward the front end. Only the portion of 120A corresponding to the large diameter portion 20A of the output shaft 20 protrudes from the bracket so as to conform to the form of 124.

In the present embodiment, as described above, in the limit plate, the cylindrical portion on which the spline is formed and the flange portion requiring surface accuracy as a friction clutch are separately formed. The molding can be performed without waste considering the precision to be performed, and the efficiency is high. In addition, it is possible to form both of these members from different materials, and the cylindrical portion 124A, which requires higher accuracy and strong strength, is obtained by cutting a central hole of, for example, a cylindrical iron, into a flange portion 124B. For example, a material capable of generating a stable frictional force, for example, a material obtained by stamping a flat stainless steel material can be used, and a more flexible design can be performed. That is, the limit plate can be manufactured under conditions that are advantageous in terms of molding efficiency.

FIG. 3 is a sectional view showing a torque limiter (222) of a power steering apparatus according to a second embodiment of the present invention. In this figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The basic configuration of this embodiment is the same as that of the first embodiment shown in FIG.
In the mechanism for pressing the limit plate against the bottom plate side of the limit cover 23, the limit plate 124 is replaced with the limit member 124 instead of the pressing member (disc spring) 26 provided adjacent to the C-ring 34. A coned disc spring 250 and a washer 251 are provided at a position in contact with the bottom plate portion, and such a configuration is also possible.

By the way, in the above configuration, there is a possibility that a lateral load indicated by an arrow F in the figure will be applied due to vibration or the like during transportation of the finished product. In this case, there is a possibility that a position shift occurs in a portion including the limit plate 124, the bush 140, the cover disks 25 and 25B, and the facing material 33 fixed via the frictional force, and the adjusted torque limiter may be displaced. Incidentally, the C ring 34 and the adjacent cover disk 25B are each formed by press molding. Therefore, the toughness (toughness) applied to the cylindrical portion 124A can be increased by combining the edge (burr) existing on the side punched when the C-ring 34 is formed with the one on the cover disk 25B side. For example, when the cover disk 25B is formed into a shape as shown in the front view of FIG. 10 and the side with the wholly contacts the C-ring 34, the edge cuts into the surface on the wholly side of the cover disk 25B and is indicated by an arrow in the figure. When such a portion is engaged, the toughness against the lateral load can be increased.

FIG. 4 is a sectional view showing a torque limiter (322) of a power steering apparatus according to a third embodiment of the present invention. In this figure, parts common to those in FIGS. 1 and 3 are denoted by the same reference numerals, and description thereof will be omitted.
The basic configuration of this embodiment is the same as that of the second embodiment shown in FIG.
24A (corresponding to 124A in FIG. 3) and flange portion 124B
(Same as FIG. 3) are directly connected without interposing the bush 140 as shown in FIG. That is, one end of the cylindrical portion 324A on the flange portion side is provided with an annular groove 32 centered on the central axis X.
4C is formed, and the flange portion is caulked and fixed such that the edge of the flange portion on the side of the mounting hole 124C at the center of the flange portion 124B is sandwiched by the annular groove 324C.

In the case of this structure, since there is no need for a bush for connecting the cylindrical portion and the flange portion, there is an effect that the number of parts of the limit plate and the number of manufacturing steps can be reduced.

FIG. 5 is a sectional view showing a torque limiter (422) of a power steering apparatus according to a fourth embodiment of the present invention. In this figure, parts common to those in FIGS. 1, 3 and 4 are denoted by the same reference numerals, and description thereof will be omitted. In the present configuration, the cylindrical portion 424A (corresponding to 324A in FIG. 4) and the flange portion 124B (same as in FIG. 4) forming the limit plate 424 are directly connected in the same manner as in the fourth embodiment. Is press-fitted. As shown in FIG. 5, a portion 424C of the cylindrical portion 424A where the lid 450 is arranged has an inner diameter increased by one step. In this configuration, as in FIG. 1, a disc spring (here, two discs) is used.
26 is provided on the C ring 34 side. Also,
According to this configuration, the input shaft 21 and the limit plate 424
There is also an effect that the intrusion of grease or the like applied to the cylindrical portion 424A can be prevented.

FIG. 6 is a sectional view showing a torque limiter (522) of a power steering apparatus according to a fifth embodiment of the present invention. In this figure, parts common to those in FIGS. 1 and 4 are denoted by the same reference numerals, and description thereof is omitted.
The torque limiter 522 in the present embodiment has the same limit plate 324 as the third embodiment shown in FIG. 4, but has a structure in which a flange portion 124B of the limit plate is pressed against the cover to generate a sliding friction force. The assembly process is different.

In FIG. 6, reference numeral 500 denotes a bottomless cylindrical case having no bottom on the output shaft 120 side.
The input shaft 21 has an annular edge 500A having a predetermined width. In the assembling of the present embodiment, the flange portion 124B of the limit plate 324 is arranged on the back side of the edge 500A of the case 500 via the annular facing material 510, and further, the annular slide member 520 and the disc spring 530 are provided.
The base 540 is attached to the case 500 via.

The base 540 has a shape having an annular portion 540A around a central portion which is press-fitted into the drive device (to which the tip of the output shaft 120 is inserted). To attach the base 540 to the case 500, a screw groove is formed in each of the outer peripheral portion of the annular portion 540A and the corresponding inner peripheral portion of the case 500, and the base 540 is attached to the case 50.
It is performed by screwing it to zero, but by adjusting the amount of screwing, the sliding friction force can be changed. Alternatively, a notch may be provided on the outer peripheral portion of the annular portion 540A, and the case 500 may be fixed to the notch by caulking.

The sliding member 520 transmits the load received from the disc spring 530 to the flange portion 124B of the limit plate 324 and participates in the sliding between the disc spring 530 and the limit plate 324. Use a material that can maintain its shape for a long period of time after receiving it. Further, the limit plate 324 of the sliding material 520 is used.
As shown in FIG. 6, it is preferable that the surface on the side contacting with the flange portion 124B has a curved surface and is in line contact with the flange portion 124B in an annular manner. This is the flange 12
This is to prevent a change in the surface in contact with 4B from affecting the slip torque. Also, the fading material 510
Is adhered to the back side of the edge 500A of the case 500,
Alternatively, the back side of the edge 500A may be roughened to be in a non-adhered state.

In the present embodiment, the assembly assembled in this way is pressed into the drive (motor) side.
The aging adjustment and the adjustment of the sliding torque can be performed independently by temporarily fixing the fixing member 40.

[0033]

As described above, according to the present invention,
In a limit plate of a torque limiter of a power steering device, a plurality of splines are formed on an inner peripheral surface, a cylindrical portion into which a shaft having a spline that can mesh with the spline is inserted, and a flange portion that requires surface accuracy as a friction clutch. Are separate from each other, so that efficient production can be performed in consideration of the forming accuracy required for each part. Further, these two members may be formed of different materials, so that the molding efficiency of the limit plate can be increased, and the accuracy and strength requirements can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a torque limiter 122 according to a first embodiment of the present invention.

FIG. 2 is a partially broken side view of a limit plate portion in the torque limiter of FIG.

FIG. 3 is a sectional view of a torque limiter 222 according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a torque limiter 322 according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a torque limiter 422 according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view of a torque limiter 522 according to a fifth embodiment of the present invention.

FIG. 7 is a sectional view showing a conventional power steering device.

8 is an (enlarged) cross-sectional view of a portion of the conventional torque limiter 22 shown in FIG.

9 is a front view of a portion of the conventional torque limiter 22 shown in FIG. 7 as viewed from the input shaft 21 side.

10 is a front view of the torque limiter 222 shown in FIG. 3 as viewed from the input shaft 21 side.

[Explanation of symbols]

Reference Signs List 21 input shaft 21A spline 23 limit cover 25A, 25B cover disk 26 pressing member (disc spring) 32 spline groove 33 facing material 34 C ring (ring-shaped member) 120 output shaft 122, 222, 322, 422, 522 torque limiter 124, 324, 424 Limit plate 124A, 324A, 424A Cylindrical part 124B Flange part 124C Mounting hole 140 Bush 250 Belleville spring 251 Washer 324C Annular groove 450 Lid 500 Case 510 Fading material 520 Sliding material 530 Belleville spring 540 Base O Axis line of output shaft 120 X Axis line of input shaft 21

Claims (4)

[Claims] 1. A power steering device comprising an output shaft of a drive device and an input shaft of a steering device connected via a torque limiter, wherein the torque limiter is rotatable integrally with one of the output shaft and the input shaft. And a driven body that is rotatable integrally with the other of the output shaft and the input shaft and is pressed against the rotating body by pressing means, and the other of the output shaft and the input shaft. A plurality of splines are formed on the outer peripheral surface of the shaft in the axial direction. The rotating body meshes with the splines formed on the other outer peripheral surfaces of the output shaft and the input shaft in the axial direction of the inner peripheral surface. And a flange portion functioning as a friction clutch when pressed by the rotating member by the pressing member. Power steering device that. 2. The power steering device according to claim 1, wherein the cylindrical portion and the flange portion are connected via a bush. 3. The power steering apparatus according to claim 1, wherein one end of the cylindrical portion is engaged with and fixed to the flange portion. 4. A power steering apparatus according to claim 3, wherein a lid for preventing grease from entering the flange portion from the one end side of the cylindrical portion is press-fitted into the cylindrical portion. .