JP2000153767A - Power steering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque limiter structure capable of easily and properly setting sliding torque, and having excellent power-transmission efficiency. SOLUTION: A flange portion 124B of a limit plate 324 is located on the back of an edge 500A of a case 500 through an annular facing member 510. Moreover, a base 540 is attached to the case 500 through an annular sliding member 520 and a belleville spring 530 for generating a pressing force between the limit plate 324 and the base 540 and achieving integral rotation by that frictional force. Since the torque limiter is assembled in this manner, the base 540 can be temporarily fixed before being mounted to a driving apparatus, so that engine adjustment and sliding torque adjustment can be done independently.

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Related Art As this type of power steering apparatus, for example, the one shown in FIGS. 2 and 3 has been proposed (unpublished application: Japanese Patent Application No. 10-91971, FIGS. 3 and 7). The output shaft 120 of the driving device (motor) 10 for generating the auxiliary steering force and the input shaft 21 connected to a steering device (not shown) of a vehicle or the like are connected to the torque limiter 2.
22 are connected.

[0003] A driving device 10 is a known direct current having a bracket 11, a yoke 12, an armature (armature) 13, a coil 14, a core 15, a magnet 16, a commutator 17, a brush 18, a bearing 19, and an output shaft 120. It is a motor. The torque limiter 222 includes a limit cover 23 that is rotatably mounted integrally with the output shaft 120,
A limit plate 124 attached to the input shaft 21 so as to be integrally rotatable, and a pair of cover disks (facing unit 25) for pressing the limit plate 124 against the limit cover 23 and rotating the limit plate 124 integrally by the frictional force. Friction plates) 25A and 25B, a disc spring 250 and a washer 251 provided at positions contacting the bottom plate of the limit cover.

[0004] The limit plate 124 has a cylindrical portion 124.
A and an annular plate-like flange portion 124B are connected via a metal bush 140. The bush 140 has a small-diameter portion 140 press-fit into the cylindrical portion 124A.
A and a large-diameter portion 140B coupled to the flange portion 124B. The large-diameter portion 140B has an annular fitting portion 1 centered on the axis of the cylindrical portion 124A (coincident with the center axis X in the figure).
40C are formed.

At the center of the flange 124B, there is provided a mounting hole 124C for mounting to the bush 140. The inner diameter of the mounting hole 124C is a concavo-convex shape for maintaining a firm connection with the bush 140. Are provided. The configuration procedure is as follows.
A bush 140 serving as a lid is swaged into the mounting hole 124C of B so that the edge of the flange portion on the mounting hole 124C side engages with the annular fitting portion 140C, and the bush 140 is pressed into the cylindrical portion 124A. And fix it. This bush 1
Reference numeral 40 also functions as a lid for preventing grease applied to the input shaft 21 provided with a spline to be described later from flowing into a friction surface with the facing unit 25 and affecting slip torque. In this configuration example, since the cylindrical portion 124A on which the spline is formed and the flange portion 124B which is required to have surface accuracy as a friction clutch are formed separately, the forming is performed in consideration of the accuracy required for each member. There is an effect that can be.

Here, a large number of spline grooves 32 extending in the direction of the central axis of the limit plate 124, that is, in the direction of the axis X of the input shaft 21, are formed in the inner peripheral surface 130 of the cylindrical portion 124A.
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, respectively.
4, the input shaft 21 is inserted into the cylindrical portion 124A by engaging the splines 21A with the spline grooves 32, so that the axis X is coaxial with the input shaft 21.
The input shaft 21 is attached to the input shaft 21 so as to be rotatable integrally therewith and to be able to advance and retreat with respect to the input shaft 21 in the axis X direction.

On the other hand, the output shaft 120 is
A number of spline grooves 27 extending in the direction of the axis O of the output shaft 120 are formed on the outer periphery of a portion 120A protruding from the bracket 11. In the present example, the limit cover 23 is formed in a substantially bottomed cylindrical shape from a lightweight metal material such as aluminum, and a mounting hole 23B is formed in the center of the bottom plate portion along the central axis of the limit cover 23. Are formed. When the protrusion 120A of the output shaft 120 is press-fitted into the mounting hole 23B, the limit cover 23 is
... bite into the inner wall of the mounting hole 23B of the limit cover 23, and are fixed to the output shaft 120 coaxially (with respect to the axis O) and integrally rotatable.

The pair of cover disks 25A, 25B
Are formed in a substantially annular plate shape whose outer diameter is a size that can be inserted into the inner periphery of the cylindrical portion 23 of the limit cover 23,
By engaging an engagement projection (not shown) with an engagement projection (not shown) provided on the limit cover 23, the engagement projection can rotate integrally with the limit cover 23, and can move forward and backward in the axis O direction. Is housed in

On the opposite end faces of the cover disks 25A, 25B, for example, annular facing members 33 formed by compression-molding a mixture of fibrous material and phenol resin are used.
Are attached so as to be able to adhere to each other. A plurality of radial grooves are provided on a surface of the facing material 33 that is in close contact with the flange portion 124B of the limit plate 124, and the depth of the groove is approximately half the thickness of the facing material 33. This groove has a function as an escape groove for wear powder of the facing material 33.

Further, a C-ring 34 (for example, JIS) is formed in the annular groove 28 formed on the opening side of the limit cover 23.
B 2804 or JIS B 28
C-shaped retaining ring such as a concentric retaining ring for a hole specified in No. 06 is fitted therein, and the inner diameter thereof is smaller than the inner diameter of the cylindrical portion 23D of the limit cover 23. By being fitted into the annular groove 28 in a slightly reduced diameter state, it is urged in a direction to expand the diameter by its elasticity and is fixed in the limit cover 23.

[0011]

In the above configuration,
Due to the pressing force of the disc spring 250, the limit plate 124 as the rotating body is pressed against the bottom plate side of the limit cover 23 as the rotating body, and the frictional force is applied between the limit plate 124 and the facing unit 25. Is generated and the motor torque is transmitted. In this case, there are the following concerns.

(1) After press-fitting the limit cover 23 into the motor, that is, the drive unit 10, the torque limiter 222 is mounted, and the aging adjustment and the slip torque are measured and adjusted. Become. In addition, there is a possibility that the degree of freedom of the above measurement and adjustment work may be limited. (2) The number of components is increased by the provision of the bush 140 for preventing the inflow of grease affecting the slip torque. Note that a configuration without a bush may be used as long as there is no problem in grease inflow. (3) In the process of transmitting the motor torque, that is, the power from the armature 13 from the limit cover 23 to the facing unit 25, rattling occurs at the fitting portion. For example, input shaft 2
FIG. 4 shows a positional relationship between the facing unit 25 and the limit cover 23 as viewed from the first side, and a circle A indicated by a broken line.
And so on. In addition, the limit plate 12
4 is sandwiched between the two cover disks 25A and 25B constituting the facing unit 25, and the power transmission path is set on both sides of the flange 124B, so that it is difficult to transmit power directly to the limit plate. It can be said. (4) Since many components are stacked, the dimensional variation from the mounting surface of the torque limiter on the drive device 10 side to the tip of the limit plate 124 is large due to tolerance due to the product pressure.

The present invention has been made under such a background, and an object of the present invention is to provide a power steering device having a torque limiter structure capable of easily and appropriately setting a sliding torque and having a high power transmission efficiency. And It is another object of the present invention to provide a power steering device having a torque limiter structure with small dimensional variations.

[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. A power steering device comprising: a cylindrical case; a base having an axial hole into which the output shaft is press-fitted; a base attached to the case; a driven body rotatable integrally with the input shaft; A torque limiter that is provided between the rotating body and a pressing unit that generates a pressing force by a frictional force. The torque limiter is configured to press-fit the output shaft into a shaft hole of the base, thereby driving the driving device. It is characterized by being connected to

Typically, the base has an annular portion around the shaft hole, and the rotated body has an annular portion facing the annular portion of the base via the pressing means. Have. The pressing means has a disc spring and a sliding member for transmitting a load received from the disc spring. The sliding material is
It is preferable to have a friction coefficient large enough to neglect the influence on slip torque when grease flows in from the input shaft. Further, the sliding member may be formed in an annular shape having one surface formed into a curved surface, and the sliding member may be pressed into contact with the rotating body so as to linearly contact the rotating body.

Further, an outer peripheral portion of the annular portion of the base has a thread groove, and the base can be assembled to the case by screwing with a thread groove formed on an inner peripheral surface of the case. . Furthermore, an annular portion may be provided inside the input shaft side end of the cylindrical case, and a friction material may be interposed between the annular portion and the annular portion of the rotating member. Further, when a cylindrical portion into which the input shaft is inserted is provided in the body to be rotated, and the output shaft is press-fitted into a shaft hole of the base, a push pin is inserted from the input shaft side end of the cylindrical portion. And pushing the base toward the output shaft.

[0017]

FIG. 1 shows a torque limiter (522) of a power steering apparatus according to an embodiment of the present invention.
FIG. In this figure, parts common to those in FIGS. 2 and 3 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 1, reference numeral 500 denotes a bottomless cylindrical case having no bottom on the output shaft 120 side, and the input shaft 21 side of the case 500 has an annular edge 500A having a predetermined width.

In the assembly of this embodiment, the flange portion 124B of the limit plate 324 is disposed on the back side of the edge 500A of the case 500 via an annular facing material 510 as a friction material.
A ring-shaped sliding member 5 for generating a pressing force between the base member 540 and the base member 540 and rotating the same integrally by the frictional force.
20, the base 540 is connected to the case 50 via the disc spring 530.
0 is attached. That is, the facing material 510 is
Since the case 500 is adhered and fixed to the case 500 which rotates integrally with the output shaft 120, there is no play as described in the problem (3) in the above-described conventional configuration.

The base 540 has a shape having an annular portion 540A around a central portion which is press-fitted into the drive device side (the tip of the output shaft 120 is press-fitted). The mounting of the base 540 to the case 500 is performed by cutting thread grooves in the outer peripheral portion of the annular portion 540A and the corresponding inner peripheral portion of the case 500, and screwing the base 540 into the case 500. This makes the sliding friction force variable. Further, notches are set at several places on the outer periphery of the annular portion 540A,
After adjusting the screwing amount of the case 500, the case 5
The adjusted sliding frictional force may be maintained more reliably by caulking the end of 00 against these notches.

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. Here, metal is used, but resin satisfying the above conditions may be used. Further, as the sliding material 520, a material having a friction coefficient μ so small that the influence on the sliding torque can be ignored even if grease flows in from the input shaft side. Thereby, even when the inflow of grease is concerned,
The conventional bush (140) functioning as a lid is not required. The sliding material 520 is a disc spring 530.
Can be transmitted to the flange portion 124B, and the shape is not limited as long as the friction coefficient μ at the contact portion with the flange portion 124B is so small as to be negligible.

In addition, by forming the cylindrical portion and the flange portion of the limit plate 324 as separate members, it is possible to perform the forming in consideration of the precision required for each member as described above. If the demands on the precision are not so high, they may be formed integrally. In addition, it is preferable that the surface of the sliding member 520 on the side of the limit plate 324 that contacts the flange portion 124B is, as shown in FIG. This is because the flange 124
This is to prevent a change in the surface in contact with B from affecting the slip torque.

The facing material 510 is provided in the case 5
The edge 500A may be adhered to the back side of the edge 500A, or the back side of the edge 500A may be roughened to be in a non-adhered state.
In the present embodiment, the assembled assembly is press-fitted into the drive (motor) side. This press-fitting is performed by inserting a push pin along the inner peripheral surface (spline surface) of the cylindrical portion 324A of the limit plate 324 and directly pressing the base 540. At this time, by inserting the push pins a predetermined distance with the tip 324L of the limit plate 324 as a position reference, it is possible to reduce the dimensional variation up to the mounting surface on the drive device 10 side. Therefore, it is possible to temporarily fix the base 540 and adjust the aging and the slip torque alone in a process before assembling the driving device, thereby reducing the line tact.

In the conventional configuration shown in FIG. 3, the flange portion 124B of the limit plate 124 is connected to two cover disks 25 constituting the facing unit 25.
A, 25B, that is, the power transmission path is set on both sides. On the other hand, in the configuration in the present embodiment, the driving device 10
, A power transmission path is set only in the direction toward, so that it is easy to set the slip torque and to easily transmit the power from the armature 13 directly to the limit plate via the base 540.

FIG. 5 is a cross-sectional view showing a configuration of a torque limiter as a modification of the above-described embodiment, and portions common to FIG. 1 are denoted by the same reference numerals and description thereof is omitted.
In FIG. 5, a step 500B for positioning the facing material 510 is provided on an edge 500A of the case 500. As a result, the facing material 510 is
Since a part of the outer peripheral surface abuts on the case 500 in addition to the surface in contact with 0A, this is effective in stably disposing the case.
In this modification, the facing material 510 is only positioned at the positioning step 500B of the case 500 and is not bonded. In this case, the friction coefficient between facing material 510 and case 500
By setting it higher than that of B, when a sliding torque is applied, it always slides on the flange portion 124B side. Then, the sliding material 520 and the flange portion 1
Sliding in a state of contact with 24B is performed similarly to the example of FIG. This makes it possible to omit the step of bonding the facing material 510 to the case 500.

FIG. 6 is a cross-sectional view showing the structure of a torque limiter as another modification of the above-described embodiment. Parts common to FIG. 1 are denoted by the same reference numerals and description thereof is omitted. In the present modification, the shape of the annular sliding member 520 on the side that contacts the flange portion 124B of the limit plate 324 does not have a curved line shape as shown in FIG.
As shown in FIG. 6, the pressure applied to the sliding member 520 is more dispersed than that of the line contact type because the shape is such that the flange portion 124B comes into (annular) surface contact with the flange portion 124B. Therefore, when importance is attached to the durability of the sliding material 520, an advantageous structure is obtained. Further, in this example, a screw groove is formed on the outer periphery of the annular portion 540A of the base 540, and a screw groove is formed on the corresponding inner peripheral surface of the case 500 (see reference numeral 500B). The sliding friction force is adjusted by adjusting the amount of screwing into the screw. Then, the screw portion is further crimped from the outside, and the screw portion is crushed to fix the two.

[0026]

As described above, according to the present invention,
Since the torque limiter of the power steering device is assembled and the assembly unit is press-fitted into the drive device, the aging adjustment and slip torque adjustment must be performed independently by temporarily fixing the base in the process before assembling to the drive device Is possible, and the line tact can be shortened. Further, pressing means for generating a pressing force between a base rotatable integrally with the output shaft and a rotating body rotatable integrally with the input shaft, and rotating these integrally by the frictional force. Is provided, the power transmission path is set only in the direction from the driven body toward the driving device, and the setting of the slip torque is easy, and the power from the armature is directly transmitted to the driven body via the base. It's easier.

Further, by using a material having a friction coefficient small enough to neglect the influence on the sliding torque as a sliding material for transmitting the load received from the disc spring, even if the inflow of grease is suspended, Such a bush functioning as a lid becomes unnecessary. In addition, as the sliding material, an annular shape having one surface formed into a curved surface is used, and the curved surface is brought into contact with the rotated object so as to make a line contact with the object to be rotated. It is possible to prevent a change in the contact surface from affecting the slip torque.

Furthermore, when a screw groove is provided on the outer peripheral portion of the annular portion of the base, and the base is assembled to the case by screwing with the screw groove cut on the inner peripheral surface of the case,
By adjusting the amount of screwing, the sliding friction force can be changed. Further, an annular portion may be provided inside the input shaft side end of the cylindrical case, and a friction material may be inserted between the annular portion and the annular portion of the rotated body. Since the friction material can be directly arranged on the case rotating integrally with the output shaft, it is possible to prevent the occurrence of the play as described in the above-mentioned problem (3) in the conventional configuration.

The rotary member is provided with a cylindrical portion into which the input shaft is inserted, and the press-fitting of the output shaft into the shaft hole of the base is pressed from the input shaft end of the cylindrical portion. This can be performed by inserting a pin and pushing the base toward the output shaft side.In this case, the push pin is inserted by a predetermined distance with the tip end of the rotated body as a position reference, so that the drive device side Variations in dimensions up to the mounting surface can be reduced. That is, according to the present invention, it is possible to realize a power steering device having a torque limiter structure that can easily and appropriately set the slip torque and has a good power transmission efficiency.

[Brief description of the drawings]

FIG. 1 shows a torque limiter 5 according to an embodiment of the present invention.
It is sectional drawing of 22 parts.

FIG. 2 is a sectional view showing a conventional power steering device.

3 is an (enlarged) cross-sectional view of a portion of a conventional torque limiter 222 shown in FIG.

FIG. 4 shows the facing unit 25 and the limit cover 23 in the torque limiter 222 of the conventional example shown in FIG.
FIG. 3 is a schematic front view for explaining the positional relationship between the input shaft 21 and the input shaft 21.

FIG. 5 is a sectional view of a torque limiter which is a modification of the embodiment.

FIG. 6 is a sectional view of a torque limiter which is another modification of the embodiment.

[Explanation of symbols]

 21 Input shaft 120 Output shaft 522 Torque limiter 324 Limit plate 324A Cylindrical part 124B Flange part 500 Case 510 Facing material 520 Sliding material 530 Disc spring 540 Base O Axis of output shaft 120 X Axis of input shaft 21

Claims (9)

[Claims] 1. A power steering device comprising an output shaft of a driving device and an input shaft of a steering device connected via a torque limiter, comprising: a cylindrical case; and a shaft hole into which the output shaft is press-fitted. Torque comprising: a base assembled to the case; a rotatable body rotatable integrally with the input shaft; and a pressing means provided between the base and the rotatable body and configured to generate a pressing force by a frictional force. A power steering device comprising a limiter, wherein the torque limiter is connected to a driving device by press-fitting the output shaft into a shaft hole of the base. 2. The base has an annular portion around the shaft hole, and the rotating body has an annular portion facing the annular portion of the base via the pressing means. 2. The power steering device according to 1. 3. The apparatus according to claim 1, wherein said pressing means has a disc spring.
A power steering device according to item 1. 4. The power steering apparatus according to claim 3, wherein said pressing means further includes a sliding member for transmitting a load received from said disc spring. 5. The power steering apparatus according to claim 4, wherein the sliding member has a friction coefficient large enough to ignore an influence on slip torque when grease flows from the input shaft. 6. The sliding member according to claim 4, wherein the sliding member has an annular shape with one surface being a curved surface, and the curved surface is brought into contact with the rotating member so as to linearly contact the rotating member. Power steering device. 7. An outer peripheral portion of an annular portion of the base has a thread groove, and the base is assembled to the case by screwing into a thread groove formed on an inner peripheral surface of the case. A power steering device according to item 1. 8. An annular portion is provided inside the end of the cylindrical case on the input shaft side, and a friction material is inserted between the annular portion and the annular portion of the driven body. Claim 2
A power steering device according to item 1. 9. The rotating body has a cylindrical portion into which the input shaft is inserted, and press-fitting of the output shaft into a shaft hole of the base is performed at an end of the cylindrical portion on the input shaft side. The power steering apparatus according to claim 1, wherein the power steering is performed by inserting a push pin from below to push the base toward the output shaft.