JP2017032105A - Shaft coupling mechanism for electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft coupling mechanism for electric power steering device which can avoid collision in a radial direction between a rotary shaft and a rotation transmission member, and which can suppress occurrence of abnormal noise which imparts an uncomfortable steering feeling to an operator.SOLUTION: A shaft coupling mechanism 1 for an electric power steering device includes: a coupling base body 3 connected to a rotary shaft 2; a coupling base body 5 connected to a rotary shaft 4; a rigid rotation transmission member 6 arranged between the rotary shaft 2 and the rotary shaft 4 via both coupling base bodies 3 and 5, and for transmitting the rotation in a direction R around a shaft center around a shaft center line O of the rotary shaft 2 to the rotary shaft 4; a pair of elastic members 7 and 8 for sandwiching the rotation transmission member 6 in the axial direction X and overlapped with the rotation transmission member 6 in the axial direction X; and connection means 9 for mutually connecting the elastic members 7 and 8 so as to prohibit mutual separation of the elastic members 7 and 8 in the axial direction X.SELECTED DRAWING: Figure 1

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 device and a rotation shaft on an operation side such as a steering shaft of an automobile.

  Electric power steering that 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 manually operated steering wheel (handle). In the apparatus, the steering shaft on the steering wheel side and the rotating shaft on the output rotating shaft side of the electric motor are connected via a shaft connecting mechanism (coupling).

  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 or soft resin in the shaft coupling mechanism.

Special table 2002-518242 gazette JP 2004-148990 A JP 2004-149070 A JP 2006-183676 A

  By the way, in Patent Document 4, a pair of rigid members that are arranged between the rotating shaft on the electric motor side and the rotating shaft on the steering side and transmit the rotation of the rotating shaft on the electric motor side to the rotating shaft on the steering side. A shaft coupling mechanism in which a rotation transmitting member and an elastic elastic member arranged between the pair of rotation transmitting members are mounted on a rotating shaft is disclosed. In such a shaft connecting mechanism, between the rotating shafts is disclosed. When a shaft center displacement (center misalignment) occurs and the rotation shaft and the rotation transmission member collide in the radial direction, since the rotation shaft and the rotation transmission member are rigid to each other, an abnormal noise (collision sound) is generated. When such a shaft coupling mechanism is used in an electric power steering apparatus for an automobile, it gives an unpleasant feeling to the occupant of the automobile, particularly an unpleasant steering feeling to the driver.

  The present invention has been made in view of the above-described points, and an object of the present invention is to provide an abnormal noise that can avoid a radial collision between the rotating shaft and the rotation transmitting member and give an unpleasant steering feeling to the driver. An object of the present invention is to provide a shaft coupling mechanism for an electric power steering apparatus that can prevent the occurrence of the above.

  A shaft according to the invention arranged between the first and second rotary shafts and connecting the first and second rotary shafts so as to transmit the rotation of the first rotary shaft to the second rotary shaft The coupling mechanism includes a rotation transmission member and a pair of elastic members that are overlapped with the rotation transmission member in the axial direction with the rotation transmission member sandwiched in the axial direction. A first base portion having an inner peripheral surface and a first outer peripheral surface, and at least a pair of first diameters spaced apart from each other in a direction around the axis and extending in a radial direction from the first outer peripheral surface Each of the pair of elastic members is overlapped with the first base in the axial direction and has a cylindrical second inner peripheral surface and a second outer peripheral surface. The second base and the first radial protrusion in the axial direction. And at least a pair of second radial protrusions extending in a radial direction from the second outer peripheral surface, and each of the second base portions has rigidity smaller than that of the first base portion and is elastic. Each of the second radial protrusions of each pair has a rigidity smaller than that of the pair of first radial protrusions and is elastically deformable, and the second diameter And having a width larger than the width in the direction around the axis of the first radial protrusion that is sandwiched in the axial direction by the directional protrusion and overlapped in the axial direction with the second radial protrusion. Each second inner peripheral surface of the second base portion sandwiching the first base portion in the axial direction has a diameter smaller than the diameter of the first inner peripheral surface.

  According to the shaft coupling mechanism of the present invention, since each of the second inner peripheral surfaces has a diameter smaller than the diameter of the first inner peripheral surface, the penetration defined by the first inner peripheral surface. When one of the first and second rotary shafts is inserted into the hole, even if an axial misalignment occurs between the first and second rotary shafts, Steering that is uncomfortable for the driver can prevent contact and collision of one rotating shaft with at least one of the pair of elastic members, thus avoiding radial collision between one rotating shaft and the rotation transmitting member. Generation of abnormal sounds that give a sense can be suppressed.

  In addition, according to the shaft coupling mechanism of the present invention, each of the pair of second radial protrusions has a rigidity smaller than that of the pair of first radial protrusions and is elastically deformable. In addition, since the first radial projecting portion that is overlapped in the axial direction with the second radial projecting portion has a width that is larger than the width in the direction around the axis, one rotating shaft As a result of the transmission of the rotation of one rotation shaft to the other rotation shaft through the elastic deformation of each pair of second radial protrusions, the transmission of the minute rotation of one rotation shaft to the other rotation shaft is performed for each pair. Each pair of second radial projections can transmit or receive a large relative rotation of one rotary shaft with respect to the other rotary shaft. Can also be carried out through a pair of first radial projections having great rigidity, and each The pair of first radial projections having a large rigidity in each of the second radial projections in the direction around the axial center of the second radial projections is a large pair of second radial projections. Since the deformation can be prevented, the mechanical fatigue due to the large deformation of the second radial protrusions of each pair can be reduced, and the resin material having low rigidity and flexibility with respect to the second radial protrusions of each pair Can be used to reduce permanent deformation of each pair of second radial protrusions due to creep of the resin material, and also through elastic deformation of each pair of second radial protrusions. Since the rotation of one rotating shaft is transmitted to the other rotating shaft, each pair of second radial protrusions can be made of a flexible and rigid resin material and one pair of second protruding portions. Reduction or prevention of transmission of minute rotation of one rotary shaft to the other rotary shaft due to the sag of the radial protrusion Since the decline or loss of fruit can be compensated by the other of the pair of second radial projections, we can maintain the reduction or blocking effect over a long period of time.

  In the present invention, the rotation transmission member is preferably formed from a hard resin such as polyacetal resin or polyamide resin, but may be formed from a hard resin exhibiting other rigidity, while a pair of elastic members. Each of these may be formed of a rubber elastic body such as urethane rubber or polyester elastomer, but instead of this, a core portion formed of a hard resin similar to the rotation transmission member, and this core It may be made of a so-called two-color molded body that covers a portion and has a covering portion made of rubber such as urethane rubber or polyester elastomer, for example, each second base portion of a pair of elastic members is A core portion made of a rigid resin such as polyacetal resin or polyamide resin, and a rigidity smaller than that of the first base and elastic deformation And a covering portion that covers the core portion, and the second base portion covering portion of the rigid rotation transmission member may be made of a rubber elastic body such as urethane rubber or polyester elastomer. It is also possible to elastically prevent contact and collision of one rotating shaft with one inner peripheral surface, and similarly, each of the second radial protrusions of each pair includes polyacetal resin, polyamide resin, etc. The core portion is made of a rubber elastic body such as urethane rubber and polyester elastomer that has a rigidity smaller than that of the first radial protrusion and is elastically deformable, and is made of a hard resin. And a small rotation of one rotating shaft to the other rotating shaft by elastic deformation of each covering portion of each pair of second radial protrusions. May be reduced or prevented, and each pair It is not necessary for the entire second radial protrusion or its covering portion to be formed of a rubber elastic body such as urethane rubber or polyester elastomer. For example, the radial direction can be deformed elastically in the direction around the axis. Each of the pair of second radial protrusions may be formed with a gap extending in a straight line.

  In a preferred example of the present invention, each of the second outer peripheral surfaces has a diameter larger than the diameter of the first outer peripheral surface.

  The shaft coupling mechanism according to the present invention includes at least a rotation transmission member disposed between two rotation shafts as a spacer in a direction around the axis and a pair of elastic members sandwiching the rotation transmission member in the axial direction. In a preferred example, the first connection base connected to the first rotation shaft and the second connection base connected to the second rotation shaft are further provided. The connection base includes a first connection base and a first axial protrusion integrally protruding in the axial direction from the first connection base, and the second connection base is a second connection base. And a second axial protrusion integrally protruding in the axial direction from the second connection base, and at least one of the first and second connection bases is The first inner peripheral surface and a pair of bullets extend in the axial direction from the central portion of one end surface in the axial direction. A shaft penetrating through a through-hole defined by the second inner peripheral surface of at least one of the elastic members, and the first axial protrusion is a pair of first in the direction around the axis. Between one radial protrusion between one radial protrusion and between one radial protrusion among each pair of second radial protrusions in the direction around the axis. The second axial projection is a second diameter of each pair in the direction between the other radial projections and in the direction around the axis among the pair of first radial projections in the direction around the axis. In order to prevent play from occurring in the initial rotation relative to the other rotation axis of one of the rotation shafts, it is arranged between the other radial projections among the direction protrusions. The first and second axial protrusions are on their respective sides in the direction around the axis, and the shafts are less than a certain relative rotation of the first and second rotational axes. Around the axis of the first radial projection facing in the direction around the axis, while contacting the side surface in the direction around the axis of each pair of second radial projections facing in the surrounding direction The first and second rotating shafts may be in non-contact with the side surface in the direction of contact, and may be in contact with the first and second rotating shafts with a relative rotation of more than a certain amount.

  In the case of this example, the first connecting base may be directly connected to and fixed to one rotating shaft, but indirectly to one rotating shaft via another rotation transmission mechanism such as a gear mechanism. The other connecting base of the second connecting base is the same.

  In the above example, the first and second shafts may be formed integrally with the central portion of the axial end surface of at least one of the first and second connection bases. It may consist of an axial end portion of at least one of the rotating shafts. In this case, each of the second outer peripheral surfaces has a diameter larger than the diameter of the first outer peripheral surface. Even if an axial misalignment occurs between the first and second rotating shafts, contact of the radially inner surfaces of the first and second axial projections with the first outer peripheral surface can be avoided. Thus, it is also possible to suppress the generation of abnormal noise that gives the driver an unpleasant steering feeling.

  In a preferred example, the shaft coupling mechanism according to the present invention further includes coupling means for coupling the pair of elastic members to each other so as to prohibit the axial separation of the pair of elastic members. In a preferred example, a first flange projecting in an axial direction from one axial end face of the first radial projecting part and integrally provided on the one end face, and a first radial projecting In the axial direction from the other end surface in the axial direction of the first portion in the axial direction to the second flange portion integrally provided on the other end surface and the first radial projecting portion A first through hole that is provided in the second radial protrusion facing the first through hole and that receives the first flange, and is provided in the second radial protrusion in the first through hole. The first step portion on which the first flange portion is hooked and the other end surface in the axial direction of the first radial protrusion A second through hole provided in the second radial protrusion facing in the axial direction and receiving the second flange; and provided in the second radial protrusion in the second through hole. And a second step portion on which the second collar portion is hooked.

  In a preferred example of the shaft coupling mechanism of the present invention including the rotation transmission member and the pair of elastic members, as described above, when the pair of elastic members are coupled to each other and the rotation transmission member via the coupling means, The assembling property can be improved and the axial separation of the pair of elastic members can be eliminated, and the spread of the pair of elastic members in the axial direction can be kept constant.

  In the present invention, each of the first and second axial protrusions may have a radially inner surface in contact with each of the second outer peripheral surfaces.

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

  According to the present invention, there is provided a shaft coupling mechanism for an electric power steering device that can avoid a collision in the radial direction between a rotating shaft and a rotation transmitting member and can suppress generation of abnormal noise that gives an unpleasant steering feeling to the driver. can do.

FIG. 1 is an exploded perspective view of the example shown in FIG. FIG. 2 is an explanatory front view of a preferred example of the embodiment of the present invention. FIG. 3 is an explanatory front sectional view of FIG. FIG. 4 is an explanatory front sectional view of the rotation transmitting member and the elastic member of FIG. FIG. 5 is a cross-sectional explanatory view taken along the line VV in FIG. 6 is a cross-sectional explanatory view taken along the line VI-VI in FIG. FIG. 7 is an explanatory diagram on the right side of the connecting base on the electric motor side in FIG. 2. FIG. 8 is a left side explanatory view of the coupling base on the steering shaft side of FIG. FIG. 9 is an explanatory side view of the rotation transmitting member of FIG. FIG. 10 is a cross-sectional explanatory view taken along the line XX in FIG. FIG. 11 is an explanatory side view of one elastic member of FIG. 12 is a cross-sectional explanatory view taken along line XII-XII in FIG. FIG. 13 is an explanatory side view of the other elastic member of FIG. 14 is a cross-sectional explanatory view taken along the line XIV-XIV 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 14, the shaft coupling mechanism 1 for the electric power steering apparatus of this example includes a coupling base 3 coupled to a rotating shaft 2, a coupling base 5 coupled to the rotating shaft 4, and both coupling bases. Rigidity that is arranged between the rotary shaft 2 and the rotary shaft 4 via 3 and 5 and transmits the rotation in the direction R around the axis O of the rotary shaft 2 to the rotary shaft 4. , A pair of elastic members 7 and 8 superimposed on the rotation transmission member 6 in the axial direction X with the rotation transmission member 6 sandwiched in the axial direction X, and the axial direction X of the elastic members 7 and 8 in the axial direction X A coupling means 9 for coupling the elastic members 7 and 8 to each other is provided so as to inhibit the mutual separation.

  The rotating shaft 2 is a rotating shaft on the electric motor side of the electric power steering apparatus, and is connected to, for example, an output rotating shaft of the electric motor, and the rotating shaft 4 rotates on the steering shaft side of the automobile. For example, it is connected to a steering shaft of an automobile.

  The rigid connection base 3 includes a disk-shaped connection base 11, a cylindrical outer peripheral surface 12 of the connection base 11, and one circular end surface 13 in the axial direction X of the connection base 11. Two pairs of axial projections 14 integrally projecting in the axial direction X from the end surface 13 and at an equal angular interval of 90 ° in the direction R, and the center of the end surface 13. A cylindrical shaft portion 15 as a shaft having a cylindrical outer peripheral surface 15a having a diameter r1 and integrally provided so as to protrude in the axial direction X from the center portion of the end surface 13; A cylindrical protrusion 17, a connecting base 11, and a protrusion 17 that are integrally provided in the central portion of the other circular end surface 16 in the axial direction X so as to protrude in the axial direction X from the central portion of the end surface 16. And one end of the rotary shaft 2 is a key and a key. Through which comprises a recess 18 which is fitted.

  Each of the axial protrusions 14 includes a pair of side surfaces 21 and 22 as a pair of rigid rotation transmission surfaces facing each other in the direction R, and arcuate protrusions connected to the side surfaces 21 and 22 and facing each other in the radial direction A. An arcuate concave inner peripheral surface 24 having a circular outer peripheral surface 23 and a diameter r2 larger than the diameter r1, and side surfaces 21 and 22 and one axial end surface 25 connected to the outer peripheral surface 23 and the inner peripheral surface 24. The side surfaces 21 and 22, the outer peripheral surface 23, and the end surface 16 are connected to each other, and the end surface 16 has the other axial end surface 26 that is flush with the end surface 16.

  The rigid connection base 5 includes an annular connection base 31 having a cylindrical outer peripheral surface 30, one annular surface 32 in the axial direction X of the connection base 31, and an axial direction X from the annular surface 32. Two pairs of axial protrusions 33 that protrude integrally and are provided integrally at an equal angular interval of 90 ° in the direction R and one end of the rotating shaft 4 are fitted via a key and a key groove. Through-holes 34.

  Each of the axial protrusions 33 also has side surfaces 41 and 42 as a pair of rigid rotation transmission surfaces facing each other in the direction R, and an arc-shaped outer periphery connected to each of the outer peripheral surface 30 and the side surfaces 41 and 42. An arc-concave inner peripheral surface 44 opposite to the outer peripheral surface 43 in the radial direction A and having the same diameter r2 as the inner peripheral surface 24, the side surfaces 41 and 42, and the outer peripheral surface 43 and the inner peripheral surface. 44 and an axial end face 45 connected to 44.

  A rigid rotation transmission member 6 integrally formed of polyacetal resin, polyamide resin or the like is arranged concentrically with the connecting base portions 11 and 31 with respect to the axis O and has a diameter larger than the diameter r1 and smaller than the diameter r2. Cylindrical inner peripheral surface 51 having r3 and cylindrical outer peripheral surface 52 and inner peripheral surface 51 having a diameter r4 larger than the diameter r3 of the inner peripheral surfaces 24 and 44 and larger than the diameter r3 of the inner peripheral surface 51. And an annular base 55 having one and the other annular end faces 53 and 54 in the axial direction X connected to the outer peripheral surface 52, and extending outwardly in the radial direction A from the outer peripheral surface 52 and integrally formed with the base 55. And four pairs of radial protrusions 56 that are spaced apart from each other at equal angular intervals of 45 ° in the direction R and that have a width d in the direction R.

  Each of the radial protrusions 56 includes an outer peripheral surface 52 and end surfaces 57 and 58 in addition to one end surface 57 in the axial direction X flush with the end surface 53 and the other end surface 58 in the axial direction X flush with the end surface 54. And side surfaces 61 and 62 as a pair of rigid rotation transmission surfaces in the direction R.

  Each of the elastic members 7 and 8 formed in the same manner has rigidity smaller than that of the connection bases 3 and 5 and the rotation transmission member 6 and is elastically deformable, and is made of a rubber elastic body such as urethane rubber or polyester elastomer. It is integrally formed.

  The elastic member 7 is concentric with the base portion 55 and overlapped with the end surface 53 at one end surface 71 in the axial direction X and has a diameter r1 smaller than the diameter r3 of the inner peripheral surface 51 and the same as the diameter r1 of the shaft portion 15. An annular base 74 having a cylindrical outer peripheral surface 73 having a diameter r2 which is the same as the diameter r2 of the cylindrical inner peripheral surface 72 and the inner peripheral surfaces 24 and 44 and larger than the diameter r4 of the outer peripheral surface 52. And extending in the radial direction A from the outer peripheral surface 73 of the base 74 that is elastically deformable with a rigidity smaller than the rigidity of the base 55 and is provided integrally with the base 74 and 45 ° in the direction R, etc. In the radial projections 56 that are spaced apart from each other at angular intervals and that are elastically deformable with a rigidity smaller than that of the radial projections 56 and that overlap in the axial direction X. Greater than width d in direction R It is provided with a radially projecting portion 75 of the four pairs having a D.

  Each of the four pairs of radial protrusions 75 includes one end face 76 in the axial direction X that is flush with the end face 71 and the other end face in the axial direction X that is flush with the other end face 77 in the axial direction X of the base 74. 78, and is connected to the outer peripheral surface 73 and the end surfaces 76 and 78 and has side surfaces 79 and 80 in the direction R.

  The elastic member 8 is concentric with the base portion 55 and overlaps the end face 54 at one end face 81 in the axial direction X and has a cylindrical inner peripheral face 82 having the same diameter r1 as the diameter r1 of the inner peripheral face 72. And an annular base 84 having a cylindrical outer peripheral surface 83 having the same diameter r2 as the diameter r2 of the outer peripheral surface 73, and a base 84 having a rigidity smaller than the rigidity of the base 55 and capable of being elastically deformed. It extends in the radial direction A from the cylindrical outer peripheral surface 83 and is provided integrally with the base 84 and is spaced apart from each other at an equal angular interval of 45 ° in the direction R, and the radial protrusion 56. It is elastically deformable with a rigidity smaller than the rigidity of the radial protrusions 56, and is larger than the width d of the radial protrusions 56 in the axial direction X and the same width as the width D of the radial protrusions 75. With four pairs of radial protrusions 85 having D To have.

  Each of the four pairs of radial protrusions 85 includes one end face 86 in the axial direction X that is flush with the end face 81, and the other end face in the axial direction X that is flush with the other end face 87 in the axial direction X of the base 84. 88 and the outer peripheral surface 83 and the end surfaces 86 and 88, and side surfaces 89 and 90 in the direction R.

  The bases 74 and 84 sandwich the base 55, and the radial projections 75 and 85 sandwich the radial projection 56 in the axial direction X, respectively. The radial projections 56, 75, and 85 are respectively It has arc-shaped outer peripheral surfaces 95, 96, and 97 having the same diameter as the outer peripheral surfaces 12, 30, and 43, respectively.

  The shaft portion 15 is passed through the through hole 98 defined by the inner peripheral surface 51 with a gap of {(r3-r1) / 2} between the outer peripheral surface 15a and the inner peripheral surface 51, and The shaft portion 15 is passed through the through hole 99 defined by the peripheral surface 72 leaving an insertion gap with respect to the inner peripheral surface 72, and the through hole 99 defined by the inner peripheral surface 82 has an inner periphery. A part of the shaft portion 15 is inserted into the surface 82 leaving an insertion gap.

  The elastic members 7 and 8 and the rotation transmitting member 6 sandwiched between the elastic members 7 and 8 in the axial direction X have bases 74 and 84 and a base 55 arranged concentrically, and these bases 74 and 84 And the base 55, and the radial protrusions 75 and 85 and the radial protrusion 56 are arranged in a line in the axial direction X so as to face each other in the axial direction X. They are connected to each other via means 9.

  The coupling means 9 has one flange 101 provided integrally with each end face 57 so as to protrude from each end face 57 in the axial direction X, and each end face 58 provided with the flange 101 in the axial direction X from the end face 58. And the other flange part 102 provided integrally in the opposite direction, the through hole 103 provided in each of the radial protrusions 75 corresponding to each of the flange parts 101, and the through hole 103 respectively. The step 104 provided in the radial protrusion 75, the through hole 105 provided in each of the radial protrusions 85 corresponding to each of the flanges 102, and the radial protrusion 85 in each of the through holes 105. And a stepped portion 106 provided on the surface.

  Each of the collar portions 101 and 102 protrudes outward in the radial direction A from the collar body 111 to the plate-shaped collar body 111 provided integrally with each of the end surfaces 57 and 58 at one end and the collar body 111, respectively. And a claw 112 provided integrally therewith.

  The coupling means 9 is configured such that each heel body 111 of the heel portion 101 is inserted into each of the corresponding through holes 103, and each of the claws 112 is hooked on the corresponding step portion 104, so that each heel body of the heel portion 102 is 111 is inserted into each of the corresponding through holes 105, and each of the claws 112 is hooked on the corresponding step portion 106, the elastic members 7 and 8 are attached to the rotation transmission member 6, and the elastic members 7 and 8 are mutually connected. The elastic members 7 and 8 are positioned with respect to the rotation transmission member 6.

  In the direction R, each of the axial protrusions 14 is between the radial protrusions 56, between the radial protrusions 75, and between the radial protrusions 85, between the radial protrusions 56, and in the radial protrusion. In the direction R, each of the axial projections 33 is arranged between the radial projections 56, between the radial projections 75, and between the radial projections 85. Among the remaining radial projections 56, between the radial projections 75 and between the radial projections 85, the relative rotation (twisting) of the rotating shafts 2 and 4 in a direction R below a certain value is provided. In other words, in the relative rotation (twisting) in the direction R below {(D−d) / 2}, each axial projection 14 has its side surfaces 21 and 22 facing each other in the direction R. 80 and 79 and 90 and 89 are in contact with each other, while the side surfaces 62 and 61 facing in the direction R are not in contact with each other. Each axial protrusion 33 is in contact with the side surfaces 80 and 79 and 90 and 89 facing in the direction R at the respective side surfaces 41 and 42 in the direction R, while the side surfaces 62 and 61 are not in contact with each other.

  The shaft connecting mechanism 1 is provided between the rotating shafts 2 and 4 and connects the rotating shafts 2 and 4 to each other so as to transmit the rotation of the rotating shaft 2 in the direction R to the rotating shaft 4. In the electric power steering apparatus, when the steering wheel is manually operated by the driver, the rotating shaft 4 is rotated in the direction R, and the rotation of the rotating shaft 4 in the direction R is performed via a transmission mechanism such as a gear (not shown). It is transmitted as a reciprocating motion to a drag link or the like 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 rotating shaft 2 is rotated in the direction R and rotated. When the rotation shaft 2 is to be rotated relative to the shaft R in the direction R to a certain value or more, that is, about half or more of the difference between the width D and the width d, the radial protrusion 75 by the axial protrusion 14 is used. , 85 after the deformation in the direction R of 85 and axial protrusions based on contact of the side surface 22 with the side surface 61 and contact of the side surface 62 with the side surface 41 or contact of the side surface 21 with the side surface 62 and contact of the side surface 61 with the side surface The rotation of the connecting base 3 in the direction R is transmitted to the axial protrusion 33 through the pressing of the radial protrusion 56 in the direction R by 14, and the connecting base 5 is rotated by the rotation of the axial protrusion 33 in the direction R. direction In the rotation, so as to assist the manual operation of the steering wheel by the addition to the driver the rotational force in the direction R of the rotary shaft 2 relative to the rotational force in the direction R of the rotary shaft 4.

  As described above, in the electric power steering apparatus provided with the shaft coupling mechanism 1, the rotation shaft 2 is rotated relative to the rotation shaft 4 in the direction R to a certain value or more, that is, about half or more of the difference between the width D and width d. In this case, the rotation of the rotating shaft 2 in the direction R is performed in response to the relative rotation in the direction R of a certain level or more by pressing the radial protrusion 56 in the direction R by the axial protrusion 14. The rotation shaft 4 is transmitted to assist the rotation of the rotation shaft 4.

  According to such a shaft coupling mechanism 1, since each of the inner peripheral surfaces 72 and 82 has a diameter r 1 smaller than the diameter r 3 of the inner peripheral surface 51, the shaft portion 15 is inserted into the through hole 98. In this case, even if an axial misalignment occurs between the rotary shafts 2 and 4, the contact and collision of the shaft portion 15 with the inner peripheral surface 51 can be prevented by at least one of the elastic members 7 and 8, and thus Collision in the radial direction A between the rotating shaft 2 and the rotation transmitting member 6 can be avoided, and generation of abnormal noise that gives an unpleasant steering feeling to the driver can be suppressed.

  In the shaft coupling mechanism 1, the steering wheel is not manually operated by the driver and the rotating shaft 4 is not rotated in the direction R, or the steering wheel is manually operated by the driver and the rotating shaft 4 is rotated in the direction R. In any of these states, when the relative rotation in the direction R of the rotating shaft 2 with respect to the rotating shaft 4 is minute within about half of the difference between the width D and the width d, the radial protrusions 75 and 85 are used. As a result, the relative rotation in the minute direction R of the rotating shaft 2 with respect to the rotating shaft 4 is hardly transmitted to the rotating shaft 4, and thus, via the shaft coupling mechanism 1 and the rotating shaft 4. The impact at the time of reversal of the electric motor and the transmission of brush vibration to the steering wheel can be reduced, and the steering feeling can be made uncomfortable. The contact of the side surface 22 and the contact of the side surface 62 with the side surface 41 or the contact of the side surface 21 with the side surface 62 and the contact of the side surface 61 with the side surface 42 are prevented, and further compression deformation of the radial protrusions 75 and 85 is suppressed. As a result, the radial protrusions 75 and 85 can be prevented from sag due to creep, and the side surfaces 21 and 22 and 41 and 42 in the direction R between the axial protrusions 14 and 33 and the radial protrusions 75 and 85. The mutual contact with the side surfaces 80 and 90 and 79 and 89 can be maintained over a long period of time, and the occurrence of backlash in the direction R between the rotating shaft 4 and the rotating shaft 2 can be eliminated. It can be made uncomfortable and has excellent durability and stable characteristics.

  That is, in the shaft coupling mechanism 1, each of the radial protrusions 75 and 85 has a rigidity smaller than that of the radial protrusion 56 and can be elastically deformed. Since the radial protrusion 56 overlapped in the axial direction X has a width D larger than the width d in the direction R, the transmission of the rotation in the direction R of the rotary shaft 2 to the rotary shaft 4 is radial. As a result of the elastic deformation of the protrusions 75 and 85, the transmission of the rotation in the minute direction R of the rotation shaft 2 to the rotation shaft 4 can be reduced or prevented by the elastic deformation of the radial protrusions 75 and 85 and the rotation. Transmission of the relative rotation in the large direction R of the shaft 2 with respect to the rotation shaft 4 to the rotation shaft 4 can be performed as it is through the radial projections 56 having rigidity greater than the radial projections 75 and 85, and , Direction R in radial projections 75 and 85 Since the radial protrusion 56 having a large rigidity can prevent large deformation of each of the radial protrusions 75 and 85 when the elastic deformation exceeds a certain level, mechanical fatigue due to the large deformation of the radial protrusions 75 and 85 is prevented. When a resin material that is flexible and has low rigidity is used for the radial protrusions 75 and 85, permanent deformation of the radial protrusions 75 and 85 due to creep of the resin material can also be reduced. Further, since the rotation in the direction R of the rotary shaft 2 is transmitted to the rotary shaft 4 through the elastic deformation of the radial projections 75 and 85, the radial projections 75 and 85 are flexible and have low rigidity. A resin material can be used, and transmission of the rotation in the minute direction R of the rotary shaft 2 to the rotary shaft 4 by one of the radial protrusions 75 and 85 can be reduced or reduced or eliminated. Of the radial protrusions 75 and 85 Since can be compensated by Chino other hand, for a long time it can be maintained the reduction or blocking effect and, moreover, since the elastic members 7 and 8 are connected to each other via the coupling means 9, thereby improving the assemblability.

  Further, according to the shaft coupling mechanism 1, since the elastic members 7 and 8 are positioned with respect to the rotation transmission member 6 with respect to the direction R and the radial direction A via the coupling means 9, The effects of the elastic members 7 and 8 can be evenly obtained with respect to both rotations in the general direction R.

  In addition, in the shaft coupling mechanism 1, since the outer peripheral surfaces 73 and 83 that contact the inner peripheral surfaces 24 and 44 have a diameter r 2 that is larger than the diameter r 4 of the outer peripheral surface 52, the inner peripheral surfaces 24 and 44. And the outer peripheral surface 52 can be avoided, and the generation of an abnormal noise that gives the driver an unpleasant steering feeling due to such a collision can also be suppressed.

  The shaft coupling mechanism 1 in the above example is composed of one elastic member 7 and 8, respectively. Alternatively, the shaft coupling mechanism 1 may be composed of two or more elastic members 7 and 8, respectively. Each of these may also consist of more than one. Further, the axial protrusions 14 and 33 of the connecting base bodies 3 and 5, the radial protrusion 56 of the rotation transmission member 6, and the radial protrusions 75 and 85 of the elastic members 7 and 8 are not limited to the above number. Further, the shaft portion 15 may be provided on the connection base portion 31, and the shaft portion 15 may be composed of an axial end portion of at least one of the rotating shafts 2 or 4.

DESCRIPTION OF SYMBOLS 1 Axis connection mechanism 2, 4 Rotating shaft 3, 5 Connection base 6 Rotation transmission member 7, 8 Elastic member

Claims (8)

  A shaft coupling mechanism that is arranged between the first and second rotary shafts and connects the first and second rotary shafts so as to transmit the rotation of the first rotary shaft to the second rotary shaft. A rotation transmission member and a pair of elastic members that are overlapped in the axial direction with the rotation transmission member sandwiched in the axial direction. The rotation transmission member is a cylindrical first member. A first base portion having an inner peripheral surface and a first outer peripheral surface, and at least a pair of first radial directions that are spaced apart from each other in a direction around the axis and that extend radially from the first outer peripheral surface Each of the pair of elastic members is overlapped with the first base portion in the axial direction and has a cylindrical second inner peripheral surface and a second outer peripheral surface. And the second radial portion and the second radial protrusion in the axial direction. And at least a pair of second radial protrusions extending in the radial direction from the outer peripheral surface, and each of the second base portions has rigidity smaller than that of the first base portion and is elastically deformable. And each of the second radial protrusions of each pair has a rigidity smaller than the rigidity of the pair of first radial protrusions and is elastically deformable, and the second radial protrusions. And having a width larger than the width in the direction around the axial center of the first radial protrusion that is sandwiched in the axial direction and superimposed on the second radial protrusion in the axial direction, Each of the second inner peripheral surfaces of the second base portion sandwiching the first base portion in the axial direction has a smaller diameter than the diameter of the first inner peripheral surface.   The shaft coupling mechanism according to claim 1, wherein each of the second outer peripheral surfaces has a diameter larger than that of the first outer peripheral surface.   A first connection base connected to the first rotation shaft; and a second connection base connected to the second rotation shaft. The first connection base is a first connection base. And a first axial protrusion that protrudes integrally in the axial direction from the first connection base, and the second connection base includes the second connection base and the second connection And a second axial protrusion integrally protruding in the axial direction from the base, and at least one of the first and second connecting bases is from a central portion of one end face in the axial direction. An axis extending in the axial direction and penetrating a through hole defined by the first inner peripheral surface and the second inner peripheral surface of at least one of the pair of elastic members; The axial protrusion is between one of the pair of first radial protrusions in the direction around the axial center and around the axial center. Between each pair of second radial protrusions, the second axial protrusion being a pair of first radial directions in a direction around the axis The other radial projections are disposed between the other radial projections between the projections and between the other radial projections of each pair in the direction around the axis. 2. The shaft coupling mechanism according to 2.   The first and second axial protrusions are on their respective sides in the direction around the axis, and for each pair of opposite rotations of the first and second rotational axes, each pair of faces facing in the direction around the axis. While contacting the side surface in the direction around the axis of the second radial projection, the side surface in the direction around the axis of the first radial projection facing in the direction around the axis, The shaft coupling mechanism according to claim 3, wherein the second rotation shaft is in non-contact when the relative rotation is less than a certain level, and is in contact when the first and second rotation shafts are more than a certain rotation.   5. The shaft coupling mechanism according to claim 3, wherein the shaft is formed of a shaft portion integrally provided at a central portion of an end surface in the axial direction of at least one of the first and second coupling bases.   The shaft coupling mechanism according to claim 3 or 4, wherein the shaft comprises an axial end portion of at least one of the first and second rotating shafts.   The shaft coupling mechanism according to any one of claims 1 to 6, further comprising coupling means for coupling the pair of elastic members to each other so as to prohibit the axial separation of the pair of elastic members. .   A shaft coupling mechanism for an electric power steering apparatus, wherein a first rotating shaft is coupled to an output rotating shaft of an electric motor, and a second rotating shaft is coupled to a steering shaft of an automobile. The shaft coupling mechanism according to any one of claims 1 to 7, wherein the shaft coupling mechanism is configured.

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