JP2013104444A - Shaft coupling mechanism for electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft coupling mechanism for an electric power steering device that hardly causes rattling, even after long-term use, in the direction around an axis between one rotary shaft and the other rotary shaft, for example, between a rotary shaft connected to an output rotary shaft of an electric motor and a steering shaft connected to a steering wheel, and can reduce an impact occurring upon reverse rotation of the electric motor and transfer of a brush vibration to the steering wheel for achieving excellent durability and giving a comfortable steering feeling.SOLUTION: The shaft coupling mechanism 1 for an electric power steering device includes: a coupling base 3 coupled to the rotary shaft 2; a coupling base 5 coupled to the steering shaft 4; and a rotation transmitting member 6 arranged between both coupling bases 3 and 5 to transmit the rotation in the R direction of the coupling base 3 to the coupling base 5 as the rotation in the R direction.

Description

  The present invention relates to a shaft coupling mechanism suitable for coupling a rotation shaft on a rotation source side such as an electric motor in an electric power steering apparatus and a rotation shaft on an operation side such as a steering shaft of an automobile.

  The electric power steering apparatus can easily perform manual steering of the steering wheel by adding the rotational force based on the rotation of the output rotation shaft of the electric motor to the rotational force based on the rotation of the manually operated steering wheel (handle). In such an electric power steering device, the steering shaft on the steering wheel side and the rotating shaft on the output rotating shaft side of the electric motor are coupled via a shaft coupling mechanism (coupling). Yes. When the steering shaft and the rotating shaft are connected via the shaft connecting mechanism, the impact when the output rotating shaft of the electric motor is reversed and the brush vibration of the electric motor are transmitted to the steering wheel via the shaft connecting mechanism and the steering shaft. There is a possibility of causing an unpleasant steering feeling to the driver, and in order to avoid this, it has been proposed to provide a spacer such as rubber in the shaft coupling mechanism as disclosed in Patent Document 1, for example.

JP 2006-177505 A

  By the way, if the spacer is made more flexible by placing importance on the reduction of impact and vibration, the flexible spacer is likely to undergo creep deformation. Therefore, the shaft coupling mechanism is not rattled by permanent deformation of the spacer due to repeated load on the spacer. This may also cause the driver's steering feeling to be uncomfortable.

  On the other hand, if the spacers are made harder with emphasis on durability, the steering feeling will be better in the absence of backlash, but the steering feeling is uncomfortable due to the impact and vibration transmitted to the steering wheel as described above. It will be a thing.

  The present invention has been made in view of the above-mentioned points. The object of the present invention is to provide a rotary shaft connected to an output rotary shaft of an electric motor, for example, the rotary shaft and the other rotary shaft, even after long-term use. For example, a backlash in the direction around the shaft center hardly occurs between the rotating shaft and the steering shaft connected to the steering wheel, for example, and it is possible to reduce the transmission of the shock and brush vibration to the steering wheel when the electric motor is reversed. Accordingly, it is an object of the present invention to provide a shaft coupling mechanism for an electric power steering apparatus that has excellent durability and does not make the steering feeling uncomfortable.

  The shaft coupling mechanism according to the present invention, which is arranged between two rotating shafts so as to transmit the rotation of one rotating shaft to the other rotating shaft and connects the two rotating shafts, is connected to one rotating shaft. The other connecting base, the other connecting base connected to the other rotating shaft, and the other connecting base being rotated between the one and the other connecting base and rotating around the axis of the one connecting base. Each of the one and the other connecting bases has a base and a protrusion integrally protruding in the axial direction from the base, and the rotation transmitting member is A base, and one fitting recess formed inside the outer peripheral edge of the base and fitted with the protrusion of one coupling base, and one fitting recess in the direction around the axis. And is formed inside the outer peripheral edge of the base and the other Has and a other of the fitting recess projection of the connecting base body is fitted, the rotation transmission member is elastically deformable in the direction about the axis.

  According to the shaft coupling mechanism of the present invention, in particular, the rotation transmission member that can be elastically deformed in the direction around the axis is formed on the inner side of the base and the outer peripheral edge of the base, and the projection of one of the coupling bases Is spaced from one fitting recess in the direction around the axis, and is formed inside the outer peripheral edge of the base and protrudes from the other connecting base. And the other fitting concave portion into which the portion is fitted, so that the compressive deformation in the direction around the axis at the portion between one of the base portion of the rotation transmitting member and the other fitting concave portion is transmitted through the rotation. As a result of being restrained by the outer peripheral edge of the base portion of the member, it is possible to prevent repeated large compressive deformation in the direction around the axis of the portion between the one and the other fitting recesses of the base portion of the rotation transmission member, and the rotation transmission member by creep Can reduce the permanent deformation of In addition, it is possible to reduce the transmission of shock and brush vibration to the steering wheel when the electric motor is reversed, and it is possible to eliminate backlash in the direction around the axis between the two rotation shafts, and to make the steering feeling uncomfortable. It can have excellent durability and stable characteristics.

  In the shaft coupling mechanism of the present invention, the base of the rotation transmission member is annular, and one and the other fitting recesses may be formed outside the inner peripheral edge of the base of the rotation transmission member.

  In the shaft coupling mechanism of the present invention, the base of the rotation transmitting member has a pair of annular surfaces opposed in the axial direction, and the one and the other fitting recesses may be bottomed recesses. In addition to or instead of these, a through hole extending in the axial direction from one annular surface to the other annular surface may be used.

  In the present invention, the rotation transmission member functioning as a spacer may be formed from a rubber elastic body such as urethane rubber or polyester elastomer, but may be formed from other elastic bodies.

  The shaft coupling mechanism of the present invention may be for an electric power steering apparatus. In this case, one rotating shaft is coupled to the output rotating shaft of the electric motor, and the other rotating shaft. The shaft may be connected to the steering shaft of the automobile.

  According to the present invention, even when used for a long time, between one rotating shaft, for example, the rotating shaft connected to the output rotating shaft of the electric motor, and the other rotating shaft, for example, the steering shaft connected to the steering wheel. Electric type that does not cause backlash in the direction around the shaft center, and that can reduce the impact of reversal of the electric motor and the transmission of brush vibrations to the steering wheel. A shaft coupling mechanism for a power steering apparatus can be provided.

FIG. 1 is an exploded perspective view of a preferred example of an embodiment of the present invention. FIG. 2 is an assembled front view of the example shown in FIG. 3 is a cross-sectional view taken along line III-III shown in FIG.

  Next, embodiments of the present invention will be described in more detail based on preferred examples shown in the drawings. The present invention is not limited to these examples.

  1 to 3, a shaft coupling mechanism 1 for an electric power steering apparatus according to this embodiment includes a coupling base 3 coupled to a rotating shaft 2 on the electric motor side of the electric power steering apparatus, and a steering as a rotating shaft. The connection base 5 connected to the shaft 4 and the rotation between the connection bases 3 and 5 and the direction around the axis of the connection base 3, that is, the rotation in the R direction, is transmitted to the connection base 5 as the rotation in the R direction. And a rotation transmitting member 6 that performs the above-described operation.

  The rigid connecting base 3 projects integrally from an annular base 11 and one annular surface 12 of the base 11 from the annular surface 12 in the axial direction, that is, the A direction, and in the direction around the axis, that is, R. Three rectangular parallelepiped protrusions 13 arranged at equal angular intervals of 120 ° in the direction, and through holes 14 provided on the base 11 and fitted with the rotary shaft 2 are provided.

  Each of the protrusions 13 has rectangular side surfaces 21 and 22 as a pair of rigid rotation transmission surfaces in the R direction, and the corners of the protrusions 13 where the side surfaces 21 and 22 intersect and the corners. A line connecting the corners of the protrusions 13 located diagonally passes through the center of the base 11.

  The rigid connection base 5 formed in the same manner as the connection base 3 is formed by integrating an annular base 16 concentrically with the base 11 and one annular surface 17 of the base 16 in the A direction from the annular surface 17. Three rectangular parallelepiped projections 18 that are projected in the R direction and arranged at equal angular intervals of 120 ° in the R direction, and through holes 19 that are provided on the base portion 16 and into which the steering shaft 4 is fitted. It has.

  Each of the protrusions 18 has rectangular side surfaces 23 and 24 as a pair of rigid rotation transmission surfaces in the R direction, and 13 corners of the protrusions intersected by the side surfaces 23 and 24 and the corners. The line connecting the corners of the protrusions located diagonally passes through the center of the base 16.

  A rotation transmission member 6 having a rigidity smaller than that of the connection bases 3 and 5 and elastically deformable and formed of a rubber elastic body such as urethane rubber or polyester elastomer is a circle arranged concentrically with the base portions 11 and 16. An annular base 31 is formed on the base 31 on the inner side of the annular outer peripheral edge 32 of the base 31 and outside the annular inner peripheral edge 33 of the base 31, and the protrusions 13 of the connection base 3 are respectively formed. One of the three fitting recesses 36 inserted is separated from each of the fitting recesses 36 in the R direction, inside the outer peripheral edge 32 of the base 31 and outside the inner peripheral edge 33. The other three fitting recesses 37 are formed in the base portion 31 and into which the protrusions 18 of the connecting base body 5 are respectively inserted.

  The base 31 arranged concentrically with the bases 11 and 16 has a pair of annular surfaces 34 and 35 facing in the A direction. The annular surface 34 is on the annular surface 12 and the annular surface 35 is on the annular surface 17. Contact.

  In this example, each of the fitting recesses 36 and 37 is a through hole extending in the A direction from the annular surface 34 to the annular surface 35, and the three fitting recesses 36 are equiangular intervals of 120 ° in the R direction. The three fitting recesses 37 are spaced apart from each other at equal angular intervals of 120 ° in the R direction, and the fitting recesses 36 and 37 are arranged in the R direction. Are arranged adjacent to each other at equal angular intervals of 60 °.

  In the R direction, one fitting recess 37 of the three fitting recesses 37 is between the two fitting recesses 36 of the three fitting recesses 36. Between the two fitting recesses 37, one of the three fitting recesses 36 is disposed, and each of the fitting recesses 36 and 37 is a side surface of the base 31 in the R direction. 38 and 39.

  The protrusions 13 of the connection base 3 are respectively in contact with the side surfaces 38 and 39 in the R direction which face each other in the R direction and define the fitting recesses 36 at the respective side surfaces 21 and 22 in the R direction. Each protrusion 18 of the base body 5 faces each other in the R direction on the side surfaces 23 and 24 in the R direction, and contacts the side surfaces 38 and 39 in the R direction that define the fitting recesses 37, respectively.

  In the electric power steering apparatus provided with the shaft coupling mechanism 1 that couples the rotating shaft 2 and the steering shaft 4 as the above two rotating shafts, when the steering wheel is manually operated by the driver, the steering shaft 4 Rotated in the R direction, the rotation of the steering shaft 4 in the R direction is transmitted as a reciprocating motion to a drag link or the like via a transmission mechanism such as a gear (not shown) to give a steering force to the steered wheels (wheels). In the manual operation of the steering wheel by the driver, when the electric motor controlled by the detection signal from the torque detector that detects the torque applied to the steering wheel is operated, the rotary shaft 2 is rotated in the R direction, and The rotation of the connecting base 3 in the R direction to the protruding portion 18 of the connecting base 5 is caused by the compression deformation in the R direction of the portion between the fitting recesses 36 and 37 of the base 31 of the rotation transmitting member 6 by the portion 13 in the R direction. Thus, the rotational force in the R direction of the rotating shaft 2 is added to the rotational force in the R direction of the steering shaft 4, thereby assisting the driver to manually operate the steering wheel. .

  The connection base 3 connected to the rotation shaft 2, the connection base 5 connected to the steering shaft 4, and the rotation of the connection base 3 in the R direction is transmitted to the connection base 5 while being arranged between the connection bases 3 and 5. The rotation transmission member 6 and the connection bases 3 and 5 respectively include base portions 11 and 16 and protrusions 13 and 18 projecting integrally from the base portions 11 and 16 in the A direction. The rotation transmitting member 6 is fitted in the R direction with a base 31 and a fitting recess 36 formed inside the outer peripheral edge 32 of the base 31 and fitted with the protrusion 13 of the connecting base 3. It is spaced apart from the concave portion 36, and is formed inside the outer peripheral edge 32 of the base portion 31, and has a fitting concave portion 37 into which the projection 18 of the coupling base 5 is fitted, and transmits rotation. The shaft linkage of this example in which the member 6 is elastically deformable in the R direction According to the mechanism 1, the compression deformation in the R direction at the portion between the fitting recesses 36 and 37 of the base 31 of the rotation transmission member 6 is suppressed by the outer peripheral edge 32 of the base 31 of the rotation transmission member 6. As a result, the rotation It is possible to prevent a large amount of repeated compression deformation in the R direction at the portion between the fitting recesses 36 and 37 of the base 31 of the transmission member 6, and to reduce permanent deformation of the rotation transmission member 6 due to creep. In addition to being able to reduce the transmission of shock and brush vibration to the steering wheel during reverse rotation, it is possible to eliminate rattling in the R direction between the rotating shaft 2 and the steering shaft 4, and to make the steering feel uncomfortable and excellent in durability The characteristic can be stable.

DESCRIPTION OF SYMBOLS 1 Shaft coupling mechanism 2 Rotating shaft 3, 5 Connecting base 4 Steering shaft 6 Rotation transmission member

Claims (4)

  An axis coupling mechanism that is arranged between two rotary shafts so as to transmit the rotation of one rotary shaft to the other rotary shaft and connects the two rotary shafts. The connecting base, the other connecting base connected to the other rotating shaft, and the rotation of the connecting base in the direction around the axis of the one connecting base to the other connecting base. A rotation transmitting member for transmitting, and each of the one and the other connecting base includes a base portion and a protrusion integrally protruding in the axial direction from the base portion. A base, one fitting recess formed inside the outer peripheral edge of the base and fitted with a projection of one connection base, and one fitting recess in the direction around the axis Spaced apart, formed inside the outer periphery of the base and connected to the other Has and a other of the fitting recess the body protrusion is fitted, the shaft coupling mechanism rotation transmission member is elastically deformable in the direction about the axis.   2. The shaft coupling mechanism according to claim 1, wherein the base of the rotation transmission member is annular, and one and the other fitting recesses are formed outside the inner peripheral edge of the base of the rotation transmission member.   The base of the rotation transmitting member has a pair of annular surfaces facing each other in the axial direction, and one and the other fitting recesses are formed of through holes extending in the axial direction from one annular surface to the other annular surface. The shaft coupling mechanism according to claim 1 or 2.   A shaft coupling mechanism for an electric power steering apparatus, wherein one rotating shaft is coupled to an output rotating shaft of an electric motor, and the other rotating shaft is coupled to a steering shaft of an automobile. The shaft coupling mechanism according to any one of claims 1 to 3, wherein the shaft coupling mechanism is configured as described above.

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