JP2005231487A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain rigidity in a rotation direction of a shaft coupling part and to reduce elastic restoration force in a radial direction applied from a metal plate of the shaft coupling to a driving gear. <P>SOLUTION: The electric power steering device is provided with the driving gear 3 interlocked/connected to an output shaft 1a of an electric motor 1 for steering assistance; and a driven gear 4 engaged with the driving gear 3 and connected to a steering means. The output shaft 1a and the driving gear 3 are interlocked/connected by the metal plate 23 having a plurality of eccentric pins 21, 22 projectedly provided on the output shaft 1a and the driving gear 3 and transmission holes 23a, 23b having edge parts internally fitted with the respective eccentric pins 21, 22 and having flexibility. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electric power steering apparatus using an electric motor as a generation source of a steering assist force.

  The electric power steering device for a vehicle includes an electric motor for assisting steering and a reduction gear mechanism that transmits a rotational force of the electric motor to the steering means, and the operation of the steering means according to the operation of the steering wheel is described above. It is configured to assist by the rotation of the electric motor and reduce the labor burden on the driver for steering.

  The reduction gear mechanism includes a drive gear coupled to the output shaft of the electric motor via a shaft coupling, and a driven gear that meshes with the drive gear and is connected to the steering means. The shaft coupling uses a serration cylinder that is serrated and fitted to the output shaft and the drive gear, and the rotational force of the output shaft is transmitted from the serration cylinder to the drive gear (for example, Patent Document 1). .

The driving gear and the driven gear are supported by rolling bearings, and the driving gear and the driven gear are engaged with each other in the direction in which the distance between the rotation centers of the driving gear and the driven gear is shortened. There is also known an electric power steering device configured to apply a preload to a portion to reduce a backlash amount of the meshing portion so as to eliminate a rattling noise caused by backlash during turning (for example, Patent Document 1). ).
JP 2002-211943 A

  However, in the electric power steering apparatus having a shaft coupling made of a serration cylinder as in Patent Document 1, an appropriate radial is used to absorb the dimensional tolerances of the serration cylinder, the output shaft, and the serration portion of the drive gear. A gap is necessary. When this radial gap becomes large, rattling occurs in the shaft coupling portion, and abnormal noise due to the rattling leaks into the passenger compartment, causing discomfort to the driver.

  In order to eliminate the backlash of the shaft coupling portion, it is desirable to use a rubber elastic body having a plurality of transmission recesses on the outer peripheral portion (see JP 2002-145083 A). However, in a shaft coupling made of an elastic body, since the rotational force of the output shaft is transmitted from the elastic body to the drive gear, it is necessary to eliminate rattling while maintaining the rigidity in the rotational direction. However, maintaining the rigidity in the rotational direction increases the overall rigidity of the elastic body, in other words, it becomes difficult to bend in the radial direction, and the elastic restoring force in the radial direction applied from the elastic body to the drive gear increases. There is a problem that the load on the rolling bearing that supports the gear increases, the rotational performance of the drive gear decreases, and the durability of the elastic body decreases. Further, when the transmission recess is bent due to the deterioration of the durability of the elastic body, the shaft coupling portion is rattled, causing abnormal noise.

  Further, when the preload is applied to the meshing portion, the drive gear swings with the support portion of the rolling bearing as a fulcrum and deviates with respect to the axis of the output shaft. In order to allow swinging with the support portion as a fulcrum, it is necessary to reduce the rigidity of the elastic body, and the rigidity in the rotational direction cannot be maintained. In addition, when the drive gear swings with the support portion of the rolling bearing as a fulcrum, the elastic body of the shaft coupling is bent in the radial direction by the elastic pressure of the elastic means, and the elastic restoring force of the elastic body is the end of the drive gear on the electric motor side. Therefore, the preload of the drive gear by the elastic means is reduced, and the drive gear may be separated from the driven gear by a meshing reaction force or the like.

  The present invention has been made in view of such circumstances, and the main object is to maintain the rigidity in the rotational direction of the shaft coupling portion, and in the radial direction applied to the drive gear from a flexible metal plate. An object of the present invention is to provide an electric power steering device that can reduce elastic restoring force. Another object is to provide an eccentric pin on the output shaft and the drive gear, and when the transmission hole for fitting the eccentric pin is provided on the elastic body of the shaft coupling, the eccentric pin can be securely attached to the transmission hole. An object of the present invention is to provide an electric power steering device that can be inserted. Another object is to provide an electric power steering device capable of preventing the eccentric pin and the transmission hole portion fitted in the transmission hole from relatively moving in the axial direction.

  An electric power steering apparatus according to a first aspect of the present invention includes a drive gear that is interlocked and connected to an output shaft of an electric motor, and a driven gear that meshes with the drive gear and is connected to steering means, and is steered by the rotation of the electric motor. In the assisting electric power steering apparatus, the output shaft and the drive gear have a transmission portion at an edge portion, and are interlocked and connected by a flexible metal plate.

  In the first invention, when the rotational force of the output shaft is transmitted from the flexible metal plate to the drive gear, the rotational force is applied in a direction orthogonal to the plate thickness direction of the metal plate. The rigidity in the rotation direction of the metal plate that is easily bent in the plate thickness direction can be maintained, and the durability of the metal plate can be obtained. Further, when the drive gear is decentered or deviated with respect to the output shaft, a metal plate having a transmission portion at the edge and configured to be easily bent in the plate thickness direction is bent in the plate thickness direction. Therefore, the radial elastic restoring force applied to the drive gear from the metal plate can be reduced. Therefore, the burden on the rolling bearing that supports the drive gear can be reduced, and the rotation of the drive gear can be maintained. Further, when the preload is applied to the meshing portion of the drive gear and the driven gear, the reduction of the preload applied by the elastic pressure means to the meshing portion can be reduced, and the state where the backlash amount of the meshing portion is small is maintained. be able to.

  An electric power steering apparatus according to a second aspect of the present invention includes a drive gear that is interlocked and connected to an output shaft of an electric motor, and a driven gear that meshes with the drive gear and is connected to steering means, and is steered by the rotation of the electric motor. In the electric power steering apparatus configured to assist, the output shaft and the drive gear are interlocked and connected by an elastic body having a bending suppression unit that suppresses bending of the output shaft in the rotation direction. .

  In the second aspect of the invention, when the rotational force of the output shaft is transmitted from the elastic body to the drive gear, the elastic body suppresses the bending of the output shaft in the rotational direction by the bending suppression means. The torque transmission function in the rotational direction can be enhanced. In addition, when the drive gear is eccentric or deviated with respect to the output shaft, the elastic body that is not restrained from bending in the direction intersecting the axis of the output shaft can be deflected in the direction intersecting the axis of the output shaft. Therefore, the radial elastic restoring force applied from the elastic body to the drive gear can be reduced. Therefore, the burden on the rolling bearing that supports the drive gear can be reduced, and the rotation of the drive gear can be maintained. Further, when the preload is applied to the meshing portion of the drive gear and the driven gear, the reduction of the preload applied by the elastic pressure means to the meshing portion can be reduced, and the state where the backlash amount of the meshing portion is small is maintained. be able to. In addition, when a torque in the rotational direction is applied to the elastic body, the elastic body can be twisted and the elastic body can be displaced in the axial direction, so that the steering load in the steering region where the electric motor is not driven can be reduced. The steering feeling can be improved.

  According to a third aspect of the present invention, there is provided an electric power steering apparatus comprising: a drive gear coupled to an output shaft of an electric motor; and a driven gear meshing with the drive gear and connected to a steering means; and steering by rotation of the electric motor. In the electric power steering apparatus configured to assist, the output shaft and the drive gear include a plurality of eccentric pins projecting from the output shaft and the drive gear, and the eccentric pins are internally fitted, and the inner peripheral portion is reinforced. It is interlockedly connected by the elastic body which has the transmission hole reinforced with the member, It is characterized by the above-mentioned.

  In the third aspect of the invention, when the rotational force of the output shaft is transmitted from the elastic body to the drive gear, the inner periphery of the transmission hole of the elastic body is reinforced by the reinforcing member, and the output shaft is bent in the rotational direction. Since it is suppressed, the rigidity of the elastic body in the rotation direction can be maintained, and the durability of the elastic body can be obtained. Further, when the drive gear is eccentric or deviated with respect to the output shaft, the elastic body can be bent in a direction intersecting the axis of the output shaft, so that the elastic recovery in the radial direction applied from the elastic body to the drive gear Power can be reduced. Therefore, the burden on the rolling bearing that supports the drive gear can be reduced, and the rotation of the drive gear can be maintained. Further, when the preload is applied to the meshing portion of the drive gear and the driven gear, the reduction of the preload applied by the elastic pressure means to the meshing portion can be reduced, and the state where the backlash amount of the meshing portion is small is maintained. be able to. Further, when the preload is applied to the meshing portion of the drive gear and the driven gear, the reduction of the preload applied by the elastic pressure means to the meshing portion can be reduced, and the state where the backlash amount of the meshing portion is small is maintained. be able to. In addition, when a torque in the rotational direction is applied to the elastic body, the elastic body can be twisted and the elastic body can be displaced in the axial direction, so that the steering load in the steering region where the electric motor is not driven can be reduced. The steering feeling can be improved.

  An electric power steering apparatus according to a fourth aspect of the invention is characterized in that the electric power steering apparatus includes blocking means for blocking relative movement of the eccentric pin and the transmission hole portion in the axial length direction.

  In the fourth invention, since the relative movement in the axial length direction of the eccentric pin and the transmission hole portion is blocked by the blocking means, the drive gear is eccentric or deviated with respect to the output shaft. However, it is possible to eliminate the relative movement of the eccentric pin and the transmission hole portion in the axial length direction, it is possible to eliminate wear due to the relative movement, and the durability of the elastic body and the eccentric pin can be improved. .

  According to the first invention, it is possible to maintain the rigidity in the rotation direction of the flexible metal plate that is easily bent in the plate thickness direction, to obtain the durability of the metal plate, and to drive from the metal plate. The radial elastic restoring force applied to the gear can be reduced, the load on the rolling bearing supporting the drive gear can be reduced, and the reduction of the preload applied to the meshing portion by the elastic means can be reduced, and the backlash of the meshing portion can be reduced. A state where the amount is small can be maintained.

  According to the second invention, the rigidity of the elastic body in the rotational direction can be maintained, the durability of the elastic body can be obtained, and the elastic restoring force in the radial direction applied from the elastic body to the drive gear can be reduced. In addition to reducing the burden on the rolling bearing that supports the drive gear, it is possible to reduce the decrease in the preload applied by the elastic means to the meshing portion, and to maintain the state where the backlash amount of the meshing portion is small. In addition, the steering load in the steering region where the electric motor is not driven can be reduced, and the steering feeling can be improved.

  According to the third invention, the rigidity of the elastic body in the rotational direction can be maintained, the durability of the elastic body can be obtained, and the radial elastic restoring force applied to the drive gear from the elastic body can be reduced. In addition to reducing the burden on the rolling bearing that supports the drive gear, it is possible to reduce the decrease in the preload applied by the elastic means to the meshing portion, and to maintain the state where the backlash amount of the meshing portion is small. In addition, the steering load in the steering region where the electric motor is not driven can be reduced, and the steering feeling can be improved.

  According to the fourth invention, even if the drive gear is eccentric or deviated with respect to the output shaft, it is possible to eliminate relative movement of the eccentric pin and the transmission hole portion in the axial length direction. It is possible to eliminate wear due to relative movement, and the durability of the elastic body and the eccentric pin can be improved.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.
Embodiment 1
FIG. 1 is an enlarged cross-sectional view of a reduction gear mechanism portion showing the configuration of the first embodiment of the electric power steering device according to the present invention, FIG. 2 is a cross-sectional view showing the entire configuration of the electric power steering device, and FIG. FIG. 4 is an enlarged cross-sectional view of a main part.

  The electric power steering device includes an electric motor 1 for assisting steering, a worm 3 as a driving gear interlocked and connected to an output shaft 1 a of the electric motor 1 via a shaft coupling 2, and a driven gear meshing with the worm 3. The reduction gear mechanism A having the worm wheel 4 and the steering means 5 connected to the worm wheel 4 are provided.

  The steering means 5 has one end connected to a steering wheel B for steering and a first steering shaft 51 having a cylindrical portion 51a at the other end, and is inserted into the cylindrical portion 51a, and one end thereof is the first. A torsion bar 52 that is connected to a cylindrical portion 51 a of one steering shaft 51 and is twisted by the action of a steering torque applied to the steering wheel B, and the other end is connected to the other end of the torsion bar 52 and is connected to the worm wheel 4. The second steering shaft 53 is connected to, for example, a rack and pinion type steering mechanism (not shown) via a universal joint.

  The worm 3 of the reduction gear mechanism A has shaft portions 3 a and 3 b at both ends, and one shaft portion 3 a is electrically driven in a state of being rotatably accommodated and supported by an aluminum support member 7 via a rolling bearing 6. The other shaft portion 3 b is housed and supported by the support member 7 via the bearing member 8 while being interlocked with the output shaft 1 a of the motor 1. The shaft portion 3 a is press-fitted into the inner ring of the rolling bearing 6. The rolling bearing 6 is an ordinary deep groove ball bearing.

  The worm wheel 4 includes a synthetic resin annular tooth body 41 having teeth on the outer peripheral portion and a metal core member 42 coupled to the inside of the annular tooth body 41. The core member 42 is a second steering member. The shaft 53 is fitted and fixed in the middle. Further, the ringing teeth 41 made of synthetic resin reduce the noise caused by the meshing with the worm 3.

  The support member 7 accommodates the worm 3, the first accommodating portion 7 a that rotatably supports the shaft portions 3 a and 3 b of the worm 3 via the rolling bearing 6 and the bearing member 8, and the worm wheel 4. It has the 2nd accommodating part 7b which supported this worm wheel 4 via the 2nd steering shaft 53 and the two rolling bearings 9 and 10 fitted to this 2nd steering shaft 53. As shown in FIG.

  The first accommodating portion 7a is elongated in the axial direction of the worm 3, and at one end in the longitudinal direction, a support hole 71 for supporting the rolling bearing 6 by loose fitting, a stepped portion 72 connected to the support hole 71, and A screw hole 73 and a motor mounting part 74 are provided, and a screw ring 11 for contacting the outer ring of the rolling bearing 6 and fixing the outer ring to the stepped part 72 is screwed into the screw hole 73. . Further, the electric motor 1 is attached to the motor attachment portion 74 with a plurality of bolts.

  The output shaft 1a of the electric motor 1 and the shaft portion 3a of the worm 3 are composed of two eccentric pins 21 and 21 protruding from the output shaft 1a, two eccentric pins 22 and 22 protruding from the shaft portion 3a, A metal plate having transmission holes 23a, 23a, 23b, and 23b as transmission portions in which the eccentric pins 21 and 22 are fitted in the edge portions, the plate thickness direction being the axial direction of the output shaft 1a, and flexibility 23 are linked together.

  The eccentric pins 21 and 21 are integrally provided at the end portions of the arms 21b and 21b extending in the radial direction from the cylindrical portion 21a fitted on the end portion of the output shaft 1a. The eccentric pins 22 and 22 are integrally provided at the ends of the arms 22b and 22b extending in the radial direction from the cylindrical portion 22a that is externally fitted to the shaft portion 3a.

  The metal plate 23 is made of spring steel, has a substantially + -shape in which four plate pieces are radially extended from the center, and a transmission hole that penetrates in the plate thickness direction at the tip of each plate piece serving as an edge. 23a and 23b are provided. Eccentric pins 21 and 21 are fitted in the transmission holes 23a and 23a of the two plate pieces at symmetrical positions, and the eccentric pins 22 and 22 are fitted in the transmission holes 23b and 23b of the remaining plate pieces. The end edges of 22 are joined together by caulking, so that the entire metal plate 23 is easily bent in the thickness direction. In addition, the metal plate 23 may have a substantially + character shape, or may be a disk shape or a square shape. The shape of the metal plate 23 is not particularly limited, but includes a recess between adjacent transmission holes 23a and 23b as illustrated. By doing so, the entire metal plate 23 can be more easily bent in the thickness direction. The eccentric pins 21 and 22 may be coupled to the metal plate 23 by caulking, or may be coupled by a coupling means such as welding.

  A receiving hole 75 for receiving the bearing member 8 and a through hole 76 facing the center of the receiving hole 75 are provided at the other end of the first receiving part 7a. A seat 77 is projected.

  The bearing member 8 includes a rolling bearing 81 having an inner ring fitted on the shaft portion 3b, and a bearing housing 82 fitted and fixed to the outer ring of the rolling bearing 81. The bearing housing 82 is externally fitted to the rolling bearing 81 and has a bottomed cylindrical portion 82a loosely fitted in the receiving hole 75. The bottom of the cylindrical portion 82a is concentrically provided with the cylindrical portion 82a, and has a through hole. The elastic member 12 includes a tension coil spring on the shaft portion 82b and the seat 77, and the worm 3 and the worm 3 and the distance between the rotational centers of the worm wheel 4 and the shaft portion 82b are inserted into the shaft portion 82b. It is repressing in the direction that H becomes shorter.

  An annular groove 83 is provided on the outer peripheral portion of the cylindrical portion 82a, and an elastic ring 84 made of a rubber O-ring is held in the annular groove 83. Further, a gap is provided between the bottom of the bearing housing 82 and the accommodation hole 75 so that the bottom does not come into contact with the support member 7.

  Further, the shaft portion 82b of the bearing housing 82 has a hooking hole drilled in a direction in which the distance H between the rotation centers becomes longer and shorter, and one end portion of the elastic member 12 (tensile coil spring) is fitted into the hooking hole. As a result, the circumferential position of the bearing housing 82 is maintained.

  The support member 7 includes a torque sensor 13 for detecting a steering torque applied to the steering wheel B by a relative rotational displacement amount of the steering shafts 51 and 53 according to the twist of the torsion bar 52, and the torque sensor The electric motor 1 is configured to be driven and controlled based on the torque and the like detected by 13.

  In the electric power steering apparatus configured as described above, when the worm 3 and the electric motor 1 are assembled, the worm 3 in which the rolling bearing 6 is externally fitted to the shaft portion 3a and the bearing member 8 is externally fitted to the shaft portion 3b. The cylindrical portion 22a of each eccentric pin 21 inserted into the first accommodating portion 7a of the support member 7 and integrally coupled with the metal plate 23 is externally fitted to the shaft portion 3a, and output to the cylindrical portion 21a of each eccentric pin 21. The electric motor 1 is attached to the motor attachment portion 74 while the shaft 1a is fitted therein, and both ends of the compression member (tensile coil spring) 12 are hooked on the shaft portion 82b and the receiving seat 77 inserted into the through hole 76 of the support member 7. By stopping, the worm 3 is elastically pressed in the direction in which the distance H between the rotation centers is shortened, and preload is applied to the meshing portion.

  The worm 3 to which the preload is applied swings in the direction in which the distance H between the rotation centers becomes shorter around the position O in the vicinity of the center in the axial direction of the rolling bearing 6, and the metal plate 23 bends in the thickness direction. In this case, the elastic pressure of the elastic member 12 is applied in the F direction, the preload is applied in the F1 direction, the force for bending the metal plate 23 is applied in the F2 direction, and the electric motor 1 side end of the worm 3 is applied to the end of the metal plate 23. Since the elastic restoring force is applied in the opposite direction to F2, the preload applied to the meshing portion is reduced. However, the eccentric pins 21 and 21 on the output shaft 1a side and the eccentric pins 22 and 22 on the worm 3 side are coupled to the edge of the metal plate 23 so that the entire metal plate 23 is easily bent in the thickness direction. Therefore, the elastic restoring force in the radial direction applied from the metal plate 23 to the worm 3 can be reduced. Since the two eccentric pins 21 and 21 and the two eccentric pins 22 and 22 are coupled to the illustrated metal plate 23 at intervals of 1/4 of the circumference, the metal plate is connected to each of the eccentric pins 21 and 22. The whole 23 can be bent in the thickness direction. Therefore, the burden on the rolling bearing 6 that supports the worm 3 can be reduced, the worm 3 can be maintained in rotation, and the decrease in the preload applied by the elastic member 12 to the meshing portion can be reduced. It is possible to maintain a state in which the amount of backlash is small. When the annular tooth body 41 of the worm wheel 4 is made of synthetic resin, the annular tooth body 41 expands due to the ambient temperature, and the annular tooth body 41 swells due to the ambient humidity. The body 41 contracts, and the annular tooth body 41 contracts due to the ambient humidity, and the deflection angle of the worm 3 also changes by this expansion and contraction.

  When the rotational force of the output shaft 1a is transmitted from the metal plate 23 to the worm 3, the rotational force is applied from the eccentric pins 21 and 22 in a direction orthogonal to the thickness direction of the metal plate 23. The rigidity in the rotation direction of the metal plate 23 that is easily bent in the plate thickness direction can be maintained, and the durability of the metal plate 23 can be obtained.

Embodiment 2
5 is an enlarged exploded perspective view of a main part showing the configuration of the electric power steering apparatus according to Embodiment 2, FIG. 6 is an enlarged sectional view of an elastic body, and FIG. 7 is a sectional view taken along line VII-VII in FIG. .
The electric power steering apparatus according to the second embodiment is a plate having a relatively thick plate such as a synthetic rubber or a synthetic resin instead of the metal plate 23 having a relatively thin plate thickness as in the first embodiment. The elastic body 24 is provided with a bending suppression means 25 that suppresses the bending of the output shaft 1a in the rotational direction.

  In the second embodiment, the elastic body 24 is formed in a disk shape having a thickness having flexibility, and the eccentric pins 21 and 21 on the output shaft 1a side and the eccentrics on the worm 3 side are provided on the outer peripheral portion. Transmission holes 24a, 24a, 24b and 24b are equally arranged as transmission parts into which the pins 22 and 22 are fitted.

  The bending suppression means 25 is a cavity in which a synthetic yarn is wound in an oval shape a plurality of times on the molding pin of a molding die in which four molding pins corresponding to the transmission holes 24a and 24b are projected from the cavity. By filling and molding a flexible material such as synthetic rubber or synthetic resin, the periphery of each transmission hole 24a, 24b and between each transmission hole 24a, 24b is reinforced with synthetic fiber 25a, and the output shaft 1a It is difficult to bend in the direction of rotation. In this case, since the synthetic fiber 25a is wound around the molding pin in an oval shape, the bending suppression effect is small in the plate thickness direction, and the bending is easy. The synthetic yarn 25a is wound around two molding pins adjacent in one direction and then wound around two molding pins adjacent in different directions, whereby both edges of the transmission holes 24a and 24b It is reinforced over the vicinity (see FIGS. 6 and 7). The material is filled between the wound synthetic yarns 25a so as to be integrated.

  In the second embodiment, the eccentric pins 21 and 21 on the output shaft 1a side are fitted in the transmission holes 24a and 24a, and the eccentric pins 22 and 22 on the worm 3 side are fitted in the transmission holes 24b and 24b. Thus, the worm 3 is pressed by the pressing member 12, and a preload is applied to the meshing portion. When the rotational force of the output shaft 1a is transmitted from the elastic body 24 to the worm 3, the rotational force is transmitted to the elastic body 24 from the transmission holes 24a, 24a in which the bending in the rotational direction is suppressed. , And the torque transmission function in the rotational direction can be enhanced. Further, durability of the elastic body 24 can be obtained.

  The worm 3 to which the preload is applied by the elastic member 12 swings in the direction in which the distance H between the rotation centers becomes smaller around the position near the center in the axial direction of the rolling bearing 6, and the elastic body 24 bends in the plate thickness direction. Since the elastic body 24 has a small effect of suppressing bending in the plate thickness direction and is easily bent, the elastic restoring force in the radial direction applied from the elastic body 24 to the worm 3 can be reduced.

  When torque in the rotational direction is applied to the elastic body 24, the elastic body 24 increases or decreases in angle θ = 90 ° between the transmission holes 24a and 24b, and the elastic body 24 is twisted to cause the transmission holes 24a and 24b. Since the axial displacement occurs during this time, in other words, a buffering effect equivalent to that of the axial damper occurs, so that the steering load in the steering region where the electric motor 1 is not driven can be reduced, and the steering feeling can be reduced. Can be improved. In other words, the electric power steering apparatus is configured such that the electric motor 1 is not driven when the steering angle is as small as about 1 °, such as when the vehicle is traveling at high speed, and the electric motor 1 is driven when the steering angle exceeds an appropriate value. Therefore, during steering in a region near the steering neutral position where the electric motor 1 is not driven, the steering force of the steering wheel A is transmitted to the output shaft 1a of the electric motor 1 via the worm wheel 4 and the worm 3, A load for rotating the output shaft 1a is applied to the steering wheel A and the steering load increases. However, since the worm 3 and the output shaft 1a are interlocked and connected by the elastic body 24, the torsional displacement of the elastic body 24 causes The steering load in the steering region where the electric motor 1 is not driven can be reduced, and the steering feeling can be improved.

  In addition, the bending suppression means 25 has a configuration including a synthetic fiber 25a wound in an oval shape around each of the adjacent transmission holes 24a and 24b, and a cylindrical body having an oval shape like the wound synthetic fiber 25a. It is good also as a structure which consists of a cylindrical body arrange | positioned around each transmission hole 24a, 24b, and a structure which consists of a plate-shaped core body.

FIG. 8 is an enlarged cross-sectional view showing another configuration of the deflection suppressing means, and FIG. 9 is a cross-sectional view taken along the line IX-IX in FIG. The bending suppression means 25 includes a substantially + -shaped core body 25b in which the plate thickness direction is the axial direction of the output shaft 1a, and four plate pieces 25c are radially extended from the center. The core body 25b is disposed in the cavity of a molding die in which four molding pins corresponding to the transmission holes 24a and 24b are projected from the cavity. In this state, synthetic rubber, synthetic resin, or the like can be placed in the cavity. By filling and molding a material having flexibility, the space between the transmission holes 24a and 24b of the elastic body 24 is reinforced by the core body 25b so that it is difficult to bend in the rotation direction of the output shaft 1a. The core body 25b is made of a material such as an iron plate, an aluminum plate, or a synthetic resin plate having higher rigidity than the elastic body 24. Even in the configuration having the deflection suppressing means 25 including the core body 25b and the like, it is possible to reduce the steering load in the steering region where the electric motor 1 is not driven.
Since other configurations and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals, and detailed description thereof and description of operations and effects are omitted.

Embodiment 3
10 is an exploded perspective view of the main part showing the configuration of the third embodiment of the electric power steering apparatus, FIG. 11 is an enlarged sectional view showing a state before the main part is assembled, and FIG. 12 is a state after the main part is assembled. It is an expanded sectional view shown.
The electric power steering apparatus according to the third embodiment includes an elastic body 24 according to the second embodiment and blocking means 26 for blocking the relative movement of the eccentric pins 21, 22 and the transmission holes 24a, 24b in the axial length direction. It is set as the structure provided with these.

  In the third embodiment, the blocking means 26 can be reduced in diameter until an annular groove 26a provided in the outer peripheral portion of each eccentric pin 21 on the output shaft 1a side and the same diameter as each eccentric pin 21 in the annular groove 26a. And a substantially C-shaped ring body 26b fitted outside. The annular groove 26a is provided at a position that is longer than the internal fitting dimension of each eccentric pin 21 to each transmission hole 24a so as to be deeper than the thickness of the annular body 26b.

  The ring body 26b has a slit at a circumferential position, and is formed with a diameter larger than the outer diameter of each eccentric pin 21 by a flexible material such as synthetic resin or metal. The outer peripheral portion of the ring body 26b has curved surfaces that are continuous with both side surfaces, and the curved surfaces can reduce the insertion resistance into each transmission hole 24a. Moreover, the both-ends edge part of each transmission hole 24a is also diameter-expanded in the taper shape.

In the third embodiment, each eccentric pin 22 on the worm 3 side is press-fitted into each transmission hole 24b, and each eccentric pin 21 on the output shaft 1a side is fitted into each transmission hole 24a. In this case, since each eccentric pin 21 is provided with an annular body 26b, when each eccentric pin 21 is fitted into each transmission hole 24a, the annular body 26b contacts the edge of the transmission hole 24a and each eccentric pin 21 is inserted. The diameter of each eccentric pin 21 is reduced to the same diameter as 21 and the entire eccentric pin 21 is inserted into each transmission hole 24a. After the whole eccentric pin 21 is fitted, the ring body 26b is elastically restored to a larger diameter than the transmission hole 24a, the ring body 26b comes into contact with the edge of the transmission hole 24a, and each eccentric pin 21 and each transmission hole The relative movement of the portion 24a in the axial length direction is prevented. Thus, since each eccentric pin 22 press-fits and each eccentric pin 21 is inserted without press-fitting, the insertion resistance of each eccentric pin 21 can be reduced. Accordingly, the elastic body 24 is attached to the shaft portion 3a of the worm 3 inserted into the first housing portion 7a via the eccentric pins 22 and 22, and the eccentric pins 21 and 21 are attached to the output shaft 1a. When the motor 1 is mounted on the motor mounting portion 74, each eccentric pin 21 can be surely fitted into each transmission hole 24a even when the electric motor 1 cannot see each transmission hole 24a of the elastic body 24 from the outside. Is possible.
Further, since the elastic body 24 is suppressed from being bent in the rotation direction of the output shaft 1a by the bending suppressing means 25, the same effect as that of the second embodiment is obtained. Since other configurations and operations are the same as those of the first and second embodiments, the same components are denoted by the same reference numerals, and the detailed description and description of the operations and effects are omitted.

Embodiment 4
13 is an exploded perspective view of the main part showing the configuration of the electric power steering apparatus according to Embodiment 4, FIG. 14 is an enlarged cross-sectional view of the elastic body, and FIG. 15 is an enlarged cross-sectional view showing a state after the main part is assembled. .
The electric power steering apparatus according to the fourth embodiment includes the elastic body 24 according to the second embodiment and a blocking means 27 that blocks relative movement of each eccentric pin 21 and each transmission hole 24a in the axial length direction. It is a thing.

  In the fourth embodiment, the blocking means 27 includes a cylindrical body 27a that can be expanded in each transmission hole 24a in which each eccentric pin 21 on the output shaft 1a side is fitted, and the eccentricity that is fitted in this cylindrical body 27a. The pin 21 expands the diameter of the cylindrical body 27a, couples each eccentric pin 21 and each transmission hole 24a without any gap, and prevents relative movement in the axial length direction of each eccentric pin 21 and each transmission hole 24a. It is like that.

  The cylindrical body 27a has a flange portion 27b at one end portion, an engaging convex portion 27c at the other end portion, a slit 27d from the other end to one end portion, and a small diameter portion 27e at the other end side of the inner peripheral surface. And is inserted into each transmission hole 24a. The eccentric pin 21 expands the diameter of the cylindrical body 27a when the tip of the eccentric pin 21 fitted in the cylindrical body 27a contacts the small diameter portion 27e.

In the fourth embodiment, each eccentric pin 22 on the worm 3 side is press-fitted into each transmission hole 24b, and each eccentric pin 21 on the output shaft 1a side is fitted into a cylindrical body 27a in each transmission hole 24a. In this case, the tip of each eccentric pin 21 comes into contact with the small diameter portion 27e of the cylindrical body 27a, the eccentric pin 21 expands the entire diameter of the cylindrical body 27a, and a gap is formed between each eccentric pin 21 and each transmission hole 24a. In this state, the eccentric pins 21 and the transmission holes 24a can be prevented from moving relative to each other in the axial length direction. Thus, each eccentric pin 22 is press-fitted and each eccentric pin 21 is fitted into the cylinder 27a in each transmission hole 24a without being press-fitted, so that the insertion resistance of each eccentric pin 21 can be reduced. Accordingly, the electric motor 1 is mounted with the elastic body 24 attached to the shaft portion 3a of the worm 3 inserted into the first housing portion 7a via the eccentric pins 22 and 22 and the eccentric pin 21 attached to the output shaft 1a. When the motor mounting portion 74 is mounted, even when the electric motor 1 cannot see the transmission holes 24a of the elastic body 24 from the outside, the eccentric pins 21 can be securely inserted into the transmission holes 24a. is there.
Further, since the elastic body 24 is suppressed from being bent in the rotation direction of the output shaft 1a by the bending suppressing means 25, the same effect as that of the second embodiment is obtained.

In the fourth embodiment, each cylindrical body 27a may have a configuration in which the flange portion 27b is connected by a circular or semicircular connecting plate portion. In this case, since the bending of the elastic body 24 in the plate thickness direction can be suppressed by the connecting plate portion, the bending of the elastic body 24 can be suppressed when each eccentric pin 21 is fitted into each transmission hole 24a. The eccentric pins 21 are easily fitted into the transmission holes 24a. Further, the cylindrical body 27a is tapered on the engagement convex portion side of the inner peripheral surface, and the eccentric pin 21 is tapered on the peripheral surface on the distal end side, whereby the insertion resistance of the eccentric pin 21 can be further reduced.
Since other configurations and operations are the same as those of the first to third embodiments, the same components are denoted by the same reference numerals, and detailed description thereof and description of the operations and effects are omitted.

Embodiment 5
16 is an exploded perspective view of the main part showing the configuration of Embodiment 5 of the electric power steering apparatus, FIG. 17 is an enlarged sectional view of the elastic body, FIG. 18 is an enlarged sectional view taken along line XVIII-XVIII in FIG. FIG. 3 is an enlarged sectional view of an elastic body.
In the electric power steering apparatus according to the fifth embodiment, the gaps between the transmission holes 24a and the eccentric pins 21 and the gaps between the transmission holes 24b and the eccentric pins 22 are relatively set in the inner peripheral portion. It is configured to be eliminated by a cylinder 28 such as a synthetic resin cylinder or a metal cylinder having a thin elastic layer 29.

  In the fifth embodiment, the cylindrical body 28 is, for example, circular or oval and is attached when the elastic body 24 is molded. Further, the elastic layer 29 is formed when the elastic body 24 is formed. In this molding, four molding pins corresponding to the transmission holes 24a and 24b are externally fitted to the molding pins of the molding die protruding from the cavity, and a material such as synthetic rubber or synthetic resin is placed in the cavity. By this molding, the inside of each elastic layer 29 becomes each transmission hole 24a, 24b by this molding, each transmission hole 24a, 24b is reinforced by each cylinder 28, and each transmission hole 24a, 24b portion is an output shaft. It becomes difficult to bend in the rotation direction of 1a. In this case, since the cylindrical body 28 is provided around each of the transmission holes 24a and 24b, the bending suppression effect is small in the plate thickness direction of the elastic body 24 and is easily bent. The cylindrical body 28 is mounted by molding, and an elastic layer 29 is provided at the time of molding, and the cylindrical body 28 provided with the elastic layer 29 on the inner peripheral portion is provided with holes corresponding to the transmission holes 24 a and 24 b of the elastic body 24. It may be mounted by a mounting means such as an adhesive or press fitting. The elastic layer 29 has the same hardness as the elastic body 24, but may have a lower hardness than the elastic body 24.

  In the fifth embodiment, since the inner side of the elastic layer 29 provided on the inner peripheral portion of the cylindrical body 28 is the transmission holes 24 a and 24 b, the eccentric pins 21 and 22 are brought into contact with the elastic layer 29. And the gap between each transmission hole 24a and each eccentric pin 21 and the gap between each transmission hole 24b and each eccentric pin 22 can be eliminated by the elastic layer 29. Occurrence can be suppressed. Moreover, since the cylinder 28 is provided around each transmission hole 24a, 24b, when the rotational force of the output shaft 1a is transmitted to each worm 3 from each eccentric pin 21, the elastic body 24, and each eccentric pin 22, The reaction force of the rotational force is applied to the outer peripheral surface of each cylindrical body 28. Since each cylinder 28 has a larger diameter than each transmission hole 24a, 24b and is inflexible, the region to which the reaction force is applied can be increased as compared with the case of only the transmission holes 24a, 24b, Accordingly, it is possible to make it difficult to bend around the transmission holes 24a and 24b. Since the rotational force is transmitted to the elastic body 24 from each transmission hole 24a in which the bending in the rotation direction is suppressed by the cylindrical body 28 in this way, the rigidity in the rotation direction of the elastic body 24 can be maintained, and the elasticity The durability of the body 24 can be obtained.

  The worm 3 to which the preload is applied by the elastic member 12 moves in the direction in which the distance H between the rotation centers becomes smaller around the position O in the vicinity of the center in the axial direction of the rolling bearing 6, and the elastic body 24 bends in the thickness direction. Since the elastic body 24 has a small effect of suppressing bending in the plate thickness direction and is easily bent, the elastic restoring force in the radial direction applied from the elastic body 24 to the worm 3 can be reduced.

Further, in the fifth embodiment, when an oval cylindrical body 28 having an elastic layer 29 on the inner peripheral portion is used as shown in FIG. 19, the distance H between the rotation centers of the elastic layer 29 is increased or decreased. The amount of bending and the amount of bending in the rotation direction of the output shaft 1a can be made different.
Since other configurations and operations are the same as those of the first and second embodiments, the same components are denoted by the same reference numerals, and the detailed description and description of the operations and effects are omitted.

In the above-described embodiment, the electric power steering device in which the distance H between the rotation centers can be adjusted has been described. However, other electric power steering devices in which the distance H between the rotation centers cannot be adjusted are also described. Good.
In the embodiment described above, the elastic member 12 made of a tension coil spring is used as the elastic means. However, an elastic member made of a compression coil spring may be used, and the structure of the elastic means and the elastic means The arrangement position is not particularly limited.
In the embodiment described above, the reduction gear mechanism A is a worm gear provided with a drive gear that is the worm 3 and a driven gear that is the worm wheel 4, but may be a bevel gear, a hypoid gear, or a helical gear. .

It is an expanded sectional view of the reduction gear mechanism part which shows the structure of Embodiment 1 of the electric power steering apparatus which concerns on this invention. It is sectional drawing which shows the whole structure of the electric power steering apparatus which concerns on this invention. It is the expansion perspective view by which the principal part was decomposed | disassembled. It is an expanded sectional view of the principal part. It is the disassembled perspective view to which the principal part which shows the structure of Embodiment 2 of the electric power steering apparatus which concerns on this invention was expanded. It is an expanded sectional view of an elastic body. It is sectional drawing of the VII-VII line of FIG. It is an expanded sectional view which shows the other structure of a bending suppression means. It is sectional drawing of the IX-IX line of FIG. It is a disassembled perspective view of the principal part which shows the structure of Embodiment 3 of the electric power steering apparatus which concerns on this invention. It is an expanded sectional view showing the state before the main part is assembled. It is an expanded sectional view showing the state after the main part is assembled. It is a disassembled perspective view of the principal part which shows the structure of Embodiment 4 of the electric power steering apparatus which concerns on this invention. It is an expanded sectional view of an elastic body. It is an expanded sectional view showing the state after the main part is assembled. It is a disassembled perspective view of the principal part which shows the structure of Embodiment 5 of the electric power steering apparatus which concerns on this invention. It is an expanded sectional view of an elastic body. It is an expanded sectional view of the XVIII-XVIII line of FIG. It is an expanded sectional view of an elastic body.

Explanation of symbols

1 Electric motor 3 Worm (drive gear)
4 Worm wheel (driven gear)
5 Steering means 21 Eccentric pin 22 Eccentric pin 23 Metal plate 23a, 23b, 24a, 24b Transmission hole (transmission part)
24 Elastic body 25 Deflection suppressing means 28 Reinforcing member 26 Blocking means 27 Blocking means

Claims (4)

  In an electric power steering apparatus comprising a driving gear interlocked with an output shaft of an electric motor, and a driven gear meshing with the driving gear and connected to a steering means, the steering assisting by rotation of the electric motor. The output shaft and the drive gear each have a transmission portion at an edge, and are interlocked and connected by a flexible metal plate.   In an electric power steering apparatus comprising a driving gear interlocked with an output shaft of an electric motor, and a driven gear meshing with the driving gear and connected to a steering means, the steering assisting by rotation of the electric motor. The electric power steering apparatus, wherein the output shaft and the drive gear are interlocked and connected by an elastic body having a deflection suppressing unit that suppresses the deflection of the output shaft in the rotation direction.   In an electric power steering apparatus comprising a driving gear interlocked with an output shaft of an electric motor, and a driven gear meshing with the driving gear and connected to a steering means, the steering assisting by rotation of the electric motor. The output shaft and the drive gear include an elastic body having a plurality of eccentric pins protruding from the output shaft and the drive gear, a transmission hole in which each eccentric pin is fitted, and an inner peripheral portion is reinforced by a reinforcing member. And an electric power steering device characterized by being linked to each other. The electric power steering apparatus according to claim 3, further comprising blocking means for blocking relative movement of the eccentric pin and the transmission hole portion in the axial length direction.

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