JP2009001240A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device capable of preventing a snap ring for fixing a bearing from being detached from a bearing supporting member and determining propriety of an assembling state of the snap ring on the bearing supporting member during an assembling process. <P>SOLUTION: A bearing 21 for supporting the output shaft 32 is internally fitted into the bearing supporting member 20 and is fixed in a non-movable state in the axial direction by the ring-shaped snap ring 27 latched to an annular groove 20a of the bearing supporting member 20. A radial direction dimension of a gap G1 between an inner periphery of the snap ring 27 and an outer periphery of the output shaft 32 or a separate member externally fitted to the output shaft 32, which is formed by a difference of an inner diameter of the snap ring 27 and an outer diameter of the output shaft 32 or a separate member fixed to the output shaft 32, is set to be smaller than a radial direction length G2 of a margin in relation to the annular groove 20a of the snap ring 27. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention detects a steering torque applied to a steering wheel by a torque sensor, generates an auxiliary steering torque from a motor corresponding to the detected steering torque, decelerates it by a speed reduction mechanism, and transmits it to an output shaft of the steering mechanism. The present invention relates to an electric power steering apparatus.

  In a steering system of an automobile, a so-called power steering device that performs steering assist using an external power source is widely adopted. Conventionally, vane type hydraulic pumps have been used as power sources for power steering devices, and many of these hydraulic pumps are driven by an engine. However, this type of power steering device has a large engine drive loss due to the constant drive of the hydraulic pump (several horsepower to about 10 horsepower at the maximum load), so it can be used in small vehicles with small displacement. It was difficult, and it was unavoidable that the fuel consumption of a car with a relatively large displacement was reduced to a level that could not be ignored.

  Therefore, in order to solve these problems, an electric power steering apparatus using a motor as a power source has been attracting attention in recent years. The electric power steering system uses an in-vehicle battery as the power source of the motor, so there is no direct engine drive loss, and since the motor is started only at the steering assist time, the fuel consumption can be prevented from being lowered. Is very easy to do.

  In the electric power steering apparatus, an auxiliary steering torque is generated from the motor in response to the steering torque applied to the steering wheel, and is decelerated by the power transmission mechanism (deceleration mechanism) and transmitted to the output shaft of the steering mechanism. It has become.

  In an electric power steering apparatus using a worm reduction mechanism as the power transmission mechanism, a worm wheel meshes with a worm attached to a motor shaft, and this worm wheel is an output shaft of a steering mechanism, for example, a pinion shaft. And is fitted to the column shaft.

  On the other hand, as a steering gear for passenger cars, a rack and pinion type is currently mainstream because of its high rigidity and light weight. The electric power steering device adopting the rack and pinion type steering gear includes a pinion assist type (or column assist type) in which a motor is provided on the side of the column in order to drive the steering shaft and the pinion itself. A ball screw type rack assist type in which a rack shaft is driven by a ball screw mechanism is also used.

For example, the applicant of the present application provides an electric power steering device according to Patent Document 1 of the prior application, and the output shaft includes a core metal portion of a worm wheel that meshes with a worm that is integral with a power auxiliary motor shaft, or The inner rings of the bearings are respectively fitted and fixed at positions adjacent to (or close to) the cored bar. This bearing is press-fitted into the inner peripheral surface of the annular bearing support member up to the enlarged diameter step portion formed on the output shaft, and is locked by a retaining ring that is latched in the annular groove of the bearing support member. Thus, it is fixed in a fixed state in the output shaft direction with respect to the bearing support member.
Japanese Patent Application No. 2006-120915

  The present invention improves the electric power steering device disclosed in the above-mentioned prior application, and even when an unexpected load is applied to the retaining ring portion, the retaining ring can be prevented from coming off from the bearing support member, It is another object of the present invention to provide an electric power steering device capable of determining whether or not the retaining ring is attached to the bearing support member during the assembly process of the output shaft.

In order to achieve the above object, an electric power steering apparatus according to the first aspect of the present invention detects a steering torque applied to a steering wheel by a torque sensor, and responds to the detected steering torque from an electric motor. A speed reduction portion that transmits the auxiliary steering torque to be generated to the output shaft of the steering mechanism is provided, and a bearing that supports the output shaft is fitted into the bearing support member, and the bearing is formed on the inner periphery of the bearing support member. In the electric power steering apparatus fixed in the axial direction by a ring-shaped retaining ring that is hooked in an annular groove and a member different from the retaining ring that is externally fitted to the output shaft,
The inner circumference of the retaining ring, the inner circumference and the diameter of the retaining ring, which are formed by the difference between the inner diameter dimension of the retaining ring and the outer diameter dimension of the output shaft or the other member fitted on the output shaft. The radial dimension of the gap between the output shaft facing in the direction or the outer periphery of the other member fitted on the output shaft is set to be smaller than the radial length of the retaining margin with respect to the annular groove of the retaining ring. It is characterized by.

According to a second aspect of the present invention, there is provided an electric power steering apparatus that detects a steering torque applied to a steering wheel by a torque sensor, and generates an auxiliary steering torque generated from an electric motor in response to the detected steering torque. A reduction gear that transmits to the output shaft of the steering mechanism is provided, and a bearing that supports the output shaft is fitted into a bearing support member, and the bearing is latched by an annular groove formed on the inner periphery of the bearing support member. An electric power steering apparatus fixedly fixed in the axial direction by a ring-shaped retaining ring and a member different from the retaining ring, which is externally fitted to the output shaft,
A shaft of a gap formed by an end surface on one side in the axial direction of the retaining ring and an end surface of the separate member that is externally fitted to the output shaft and that is opposed to the end surface on the one side of the retaining ring in the axial direction. The dimension in the direction is set to be smaller than the axial length of the hooking allowance with respect to the annular groove of the retaining ring.

Preferably, in the electric power steering apparatus according to the third aspect of the present invention, auxiliary steering that detects a steering torque applied to the steering wheel by a torque sensor and generates from the electric motor in response to the detected steering torque. A speed reduction portion that transmits torque to the output shaft of the steering mechanism is provided, and a bearing that supports the output shaft is fitted into a bearing support member, and the bearing is engaged with an annular groove formed on the inner periphery of the bearing support member. In the electric power steering apparatus fixedly fixed in the axial direction by a ring-shaped retaining ring to be stopped and a member different from the retaining ring, which is externally fitted to the output shaft,
The inner circumference of the retaining ring, the inner circumference and the diameter of the retaining ring, which are formed by the difference between the inner diameter dimension of the retaining ring and the outer diameter dimension of the output shaft or the other member fitted on the output shaft. The radial dimension of the gap between the output shaft facing in the direction or the outer periphery of the other member fitted on the output shaft is set to be smaller than the radial length of the retaining margin with respect to the annular groove of the retaining ring. And an end face on one side in the axial direction of the retaining ring, and an end face of the separate member that is externally fitted to the output shaft, facing the end face on the one side of the retaining ring in the axial direction. The axial dimension of the gap is set to be smaller than the axial length of the hooking allowance of the retaining ring with respect to the annular groove.

According to a fourth aspect of the present invention, there is provided an electric power steering apparatus that detects a steering torque applied to a steering wheel by a torque sensor, and generates an auxiliary steering torque generated from the electric motor in response to the detected steering torque. A reduction gear that transmits to the output shaft of the steering mechanism is provided, and a bearing that supports the output shaft is fitted into a bearing support member, and the bearing is latched by an annular groove formed on the inner periphery of the bearing support member. An electric power steering apparatus fixedly fixed in the axial direction by a ring-shaped retaining ring and a member different from the retaining ring, which is externally fitted to the output shaft,
A radius r of a retaining ring insertion hole formed in the bearing support member, a radial width L of the retaining ring, and an inner circumference and a diameter of the separate member that are externally fitted to the output shaft. The relation with the radius R of the outer periphery facing in the direction is r−L <R.

Preferably, the electric power steering device according to claims 1 to 3 detects a steering torque applied to the steering wheel by a torque sensor, and generates an auxiliary steering torque generated from the electric motor corresponding to the detected steering torque. A speed reduction portion that transmits to the output shaft of the steering mechanism, and a bearing that supports the output shaft is fitted into a bearing support member;
The bearing is axially formed by a ring-shaped retaining ring that is latched by an annular groove formed on the inner periphery of the bearing support member, and a member that is externally fitted to the output shaft and is separate from the retaining ring. In the electric power steering device fixedly fixed to
A radius r of a retaining ring insertion hole formed in the bearing support member, a radial width L of the retaining ring, and an inner circumference and a diameter of the separate member that are externally fitted to the output shaft. The relation with the radius R of the outer periphery facing in the direction is r−L <R.

  As described above, according to the first aspect of the present invention, the radial clearance between the retaining ring and the output shaft or another member that is externally fitted to the output shaft is equal to the diameter of the allowance for the annular groove of the retaining ring. Since the length is set to be smaller than the length in the direction, even when an unexpected load is applied to the retaining ring, even if the retaining ring is displaced in the axial direction, the engagement allowance is not completely detached from the annular groove. Even if the retaining ring shifts in the axial direction and comes into contact with the output shaft or another member that is externally fitted to the output shaft, it can return to its original position when a reverse load is applied. In this case, it is possible to prevent the retaining ring from being completely removed from the annular groove and causing backlash in the output shaft, which can lead to a serious failure.

  According to the second aspect of the present invention, the axial clearance between the retaining ring and another member fitted on the output shaft is set to be smaller than the axial length of the allowance for the annular groove of the retaining ring. Therefore, when an unexpected load is applied to the retaining ring, even if the retaining ring is displaced in the axial direction, the engagement allowance is not completely removed from the annular groove.

  According to the invention described in claim 3, the radial clearance between the retaining ring and the output shaft or another member fitted on the output shaft is the radial length of the allowance with respect to the annular groove of the retaining ring. Since the axial clearance dimension between the retaining ring and another member fitted on the output shaft is set smaller than the axial length of the hooking allowance with respect to the annular groove of the retaining ring, it is unexpected. When the retaining ring is loaded on the retaining ring, even if the retaining ring is displaced in the radial direction or the axial direction, the engagement allowance is not completely removed from the annular groove.

  According to the invention of claim 4, the radius r of the retaining ring insertion hole formed in the bearing support member, the radial width L of the retaining ring, and the separate member fitted on the output shaft Since the relationship between the inner periphery of the retaining ring and the radius R of the outer periphery that is opposed in the radial direction is set to r−L <R, the outer ring is fitted to the retaining ring and the output shaft during the assembly process of the output shaft. It is possible to determine whether the assembly state of the retaining ring to the bearing support member is good or not.

  Furthermore, according to the invention described in claim 5, during the assembly process of the output shaft, it is possible to judge whether the retaining ring is assembled to the bearing support member, and an unexpected load is applied to the retaining ring. In this case, even if the retaining ring is displaced in the radial direction or the axial direction, the engagement allowance is not completely detached from the annular groove.

  Hereinafter, an electric power steering apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a pinion assist type electric power steering device, and FIG. 2 is a partial cross-sectional view showing a unit portion and a rack housing of the electric power steering device of FIG.

  First, an outline of the overall configuration of a pinion assist type electric power steering apparatus according to the present invention will be described.

  In FIG. 1, the steering wheel 1 is connected to an upper shaft 2 a that constitutes an upper portion of the steering shaft 2. The lower end of the upper shaft 2a is connected to the upper end of the lower shaft 2b via the universal joint 4, and the lower end of the lower shaft 2b is connected to the input shaft 31 of the electric power steering device via the universal joint 5. ing.

  A rack shaft 22 (see FIG. 2) is inserted into the rack housing 8, and the rack shaft 22 is connected to tie rods 9 and 10 at both ends thereof. The tie rods 9 and 10 are connected to a steering mechanism (not shown).

  The electric power steering apparatus includes an input shaft 31, an output shaft 32, a torque sensor unit 3, a controller 13, an electric motor 23, and a speed reduction unit.

  The torque sensor unit 3 detects the steering torque transmitted to the input shaft 31, for example, converts the steering torque into a torsional angular displacement of a torsion bar 33 interposed between the input shaft 31 and the output shaft 32, The torsional angle displacement is configured to be detected magnetically or mechanically, and the magnitude and direction of torsion generated between the input shaft 31 and the output shaft 32 when the operator steers the steering wheel 1. A torque detection signal Tv composed of an analog voltage corresponding to is output to the controller 13.

  For example, when the steering wheel 1 is in a neutral state, the torque sensor unit 3 outputs a predetermined neutral voltage as the torque detection signal Tv. When the steering wheel 1 is turned clockwise from this, the steering at that time is performed. When the voltage that increases from the neutral voltage according to the torque is counterclockwise, a voltage that decreases from the neutral voltage according to the steering torque at that time is output.

  A pinion 30 (see FIG. 3) is provided at the lower end of the output shaft 32, and the pinion 30 meshes with the rack teeth of the rack shaft 22. As will be described later, the driving force of the motor 23 is transmitted to the output shaft 32 via a worm gear mechanism that is a speed reducing portion. The input / output shafts 31 and 32, the motor 23, the worm gear mechanism, and the like are incorporated in the unit portion 25 (see FIG. 2).

  A controller 13 is provided as a control unit for driving and controlling the motor 23 and controlling the steering assist force to the steering system. The controller 13 operates by being supplied with power from a vehicle-mounted battery 16. The negative electrode of the battery 16 is grounded, and its positive electrode is connected to the controller 13 via an ignition switch 14 and a fuse 15a for starting the engine, and directly connected to the controller 13 via a fuse 15b. The power supplied via 15b is used for memory backup, for example.

  The controller 13 can drive and control the motor 23 based on a torque detection signal Tv from the torque sensor unit 3 and a vehicle speed detection signal Vp from a vehicle speed sensor 17 disposed on an output shaft of a transmission (not shown), for example. it can.

  FIG. 3 is an axial sectional view showing the pinion assist type electric power steering apparatus according to the first embodiment of the present invention, and FIG. 4 is a partially enlarged view showing a portion A of FIG.

  As shown in FIG. 3, the torsion bar 33 extends inside the hollow input shaft 31, and its proximal end is press-fitted into the output shaft 32, and its distal end is fixed to the input shaft 31 by the fixing pin 34. It is fixed to the end of the.

  A torque sensor unit 3 is provided around the input shaft 31. That is, the detection groove 35 of the torque sensor unit 3 is formed on the vehicle front side of the input shaft 31 (the lower side in FIG. 3), and the torque sensor unit 3 is formed radially outward of these grooves 35. The sleeve 36 is arranged. The sleeve 36 is fixed to the output shaft 32 by caulking or the like. A coil 37, a circuit board, and the like are provided outside the sleeve 36 in the radial direction. In the sleeve 36, a plurality of rectangular windows 36b extending in the axial direction facing the detection groove 35 are formed at equal intervals.

  A worm wheel 39 meshing with a worm 38 attached to the shaft of the electric motor 23 is fixed to the output shaft 32. The worm wheel 39 is composed of a core metal 39a fitted and fixed to the output shaft 32, and resin gear teeth 39b formed on the core metal 39a.

  In the present embodiment, the torque sensor unit 3, the input / output shafts 31 and 32, the speed reduction unit, and the electric motor 23 form a unit unit 25 and are detachably attached to the rack housing 8.

  The worm 38 and the worm wheel 39 are accommodated in the gear housing 24 and the bearing support member 20 formed integrally with the gear housing 24. The gear housing 24 is integrally formed with a sensor housing 24b extending rearward of the vehicle (upward in FIG. 3).

  The input shaft 31 of the unit portion 25 is pivotally supported by a first bearing 18 interposed on the inner wall of the sensor housing 24 b, and the output shaft 32 is a second bearing 21 fitted inside the inner peripheral surface of the annular bearing support member 20. It is supported by. In the second bearing 21, the vehicle axial rear end surface of the inner ring 21 b is in contact with the vehicle axial front end surface of the base portion 39 c formed on the metal core 39 a of the worm wheel 39. 39c, the output shaft 32, and the inner ring 21b are fixed so as to be integrally rotatable.

  Therefore, the steering force generated when the driver steers the steering wheel 1 is transmitted to the steered wheels (not shown) via the input shaft 31, the torsion bar 33, the output shaft 32, and the rack and pinion type steering device. . Further, the rotational force of the electric motor 23 is transmitted to the output shaft 32 through the worm 38 and the worm wheel 39, and the controller 13 appropriately controls the rotational force and the rotational direction of the electric motor 23. Accordingly, an appropriate steering assist torque can be applied to the output shaft 32.

  As shown in an enlarged view in FIG. 4, the second bearing 21 is fitted into an annular groove 20 a provided in the bearing support member 20 by press-fitting an outer ring 21 a to the stepped portion 20 b on the inner peripheral surface of the bearing support member 20. By being locked by the retaining ring 27, it is fixed to the bearing support member 20 in a fixed state in the axial direction of the output shaft 32. The second bearing 21 is preferably a four-point contact bearing.

  As shown in FIG. 4, the inner ring dimension of the retaining ring 27 is determined by the difference between the inner diameter dimension of the retaining ring 27 and the outer diameter dimension of the base portion 39 c of the metal core 39 a that is externally fitted to the output shaft 32. The radial dimension of the gap G1 formed between the circumference and the outer circumference of the base portion 39c of the cored bar 39a is smaller than the radial length G2 of the engagement margin with respect to the annular groove 20a of the retaining ring 27 (G1 <G2 ) Is set as follows.

  In the above configuration, as shown in FIG. 4, the radial dimension of the gap G1 between the inner periphery of the retaining ring 27 and the outer periphery of the base portion 39c of the core metal 39a is the radial direction of the allowance for the annular groove 20a of the retaining ring 27. Therefore, even when an unexpected load is applied to the retaining ring 27, even if the retaining ring 27 is displaced in the axial direction, the allowance for the retaining ring 27 is not limited to the annular groove 20 a. There will be no departure. Even if the retaining ring 27 is displaced in the axial direction and the inner periphery of the retaining ring 27 comes into contact with the outer periphery of the base portion 39c of the cored bar 39a, when the load in the reverse direction is applied, the retaining ring 27 is in a predetermined position. Since it is also possible to return, the retaining ring 27 is not completely detached from the annular groove 20a. Therefore, it is possible to prevent the output shaft 32 from becoming loose and developing into a serious failure.

  Since the radial dimension of the gap G1 between the retaining ring 27 and the cored bar 39a is set to be relatively small as described above, when the bearing support member 20 in which the second bearing is fitted is assembled to the output shaft 32. If the retaining ring 27 is not assembled at an appropriate position, the retaining ring 27 and the cored bar 39a are easily in contact with each other. Therefore, in the assembly process, it can be determined whether the retaining ring 27 is assembled properly. Therefore, it is possible to double check the check at the time of assembling the retaining ring 27 and the check after the assembling.

  FIG. 5 shows a modification of the first embodiment, and is an enlarged view corresponding to a portion A in FIG. In the first modification, the outer periphery of the vehicle front side end portion of the base portion 39c formed on the core metal 39a of the worm wheel 39 forms a reduced diameter portion 39e. In this modification, the shape and configuration of the bearing support member 20 are the same as those of the first embodiment of FIG. 4, and the bearing ring 27 and the nut 50 are latched by the annular groove 20 a formed on the inner periphery. Two bearings 21 are supported and fixed in the axial direction. In this modification, the gap G1 between the retaining ring 27 and the cored bar 39a is between the inner peripheral surface of the retaining ring 27 and the outer periphery of the reduced diameter part 39e formed in the base part 39c of the cored bar 39a. 27 and the radial gap G1) of the metal core 39a) <(radial length G2 of the hooking ring 27a with respect to the annular groove 20a).

  FIG. 6 shows only a part different from the first embodiment (that is, a part corresponding to part A in FIG. 3) in the second embodiment of the present invention. In the second embodiment, the part shown in FIG. 6 different from the first embodiment will be described.

  Also in the second embodiment, the arrangement of the constituent members of the input shaft 31, the output shaft 32, the cored bar 39a, the retaining ring 27, the second bearing 21 and the nut 50 is the same as in the first embodiment. In the second embodiment, the base portion 39c of the cored bar 39a is, as in the modification of the first embodiment shown in FIG. 5, the vehicle front side end portion being the reduced diameter portion 39e, and the inner periphery of the retaining ring 27 is the reduced diameter portion. It faces the outer periphery of 39e in the radial direction. The second embodiment is different from the first embodiment in the arrangement state of the retaining ring 27.

  In the second embodiment, as shown in FIG. 6, the gap G <b> 3 formed by the vehicle axial direction rear end surface of the retaining ring 27 and the vehicle axial direction front end surface of the base portion 39 c of the core metal 39 a that is externally fitted to the output shaft 32. The dimension in the axial direction is set to be smaller than the axial length G4 of the engagement allowance of the retaining ring 27 with respect to the annular groove 20a (G3 <G4).

  In the above configuration, as shown in FIG. 6, the axial dimension of the gap G3 between the rear end surface in the vehicle axial direction of the retaining ring 27 and the front end surface in the vehicle axial direction of the cored bar 39a depends on the annular groove 20a of the retaining ring 27. Since the axial length G4 is set to be smaller than the allowance G4, even when an unexpected load is applied to the retaining ring 27, even if the retaining ring 27 is displaced in the axial direction, the engagement allowance G4 remains in the annular groove 20a. There will be no departure. Even if the retaining ring 27 is displaced in the axial direction, it is possible to return to a predetermined position when a load in the opposite direction is applied, so that the retaining ring 27 is completely detached from the annular groove 20a. It is possible to prevent the output shaft 32 from becoming loose and developing into a serious failure.

  Thus, the axial dimension of the gap G3 between the retaining ring 27 and the cored bar 39a is set to be relatively small, and the retaining ring 27 and the cored bar 39a are easily in contact with each other. When the bearing support member 20 fitted inside is assembled to the output shaft 32, if the retaining ring 27 is not assembled at an appropriate position, the retaining ring 27 and the metal core 39a come into contact with each other. Can be judged whether or not. Therefore, as in the first embodiment, a double check can be performed when the retaining ring 27 is assembled and after the assembly.

  FIG. 7 shows a third embodiment of the present invention. Also in the third embodiment, the arrangement of the constituent members of the input shaft 31, the output shaft 32, the core metal 39a, the retaining ring 27, the second bearing 21 and the nut 50 is the same as in the first and second embodiments.

  The third embodiment includes both characteristic configurations of the first embodiment and the second embodiment. That is, in the third embodiment, the radial gap relationship between the retaining ring 27 and the cored bar 39a (G1 <G2) is the same as that of the first embodiment, and the shaft of the retaining ring 27 and the cored bar 39a is the same. The relationship between the direction gaps (G3 <G4) is the same as in the second embodiment. Therefore, the third embodiment has the effects of both the first and second embodiments.

  FIG. 8 shows a fourth embodiment of the present invention, and FIG. 9 shows a modification of the fourth embodiment, in which the bearing support member 20 having the second bearing 21 fitted therein is assembled to the output shaft 32. The inside state is shown.

  In the fourth embodiment shown in FIGS. 8 and 9 and its modification, the arrangement of the constituent members of the input shaft 31, the output shaft 32, the cored bar 39a, the retaining ring 27, the second bearing 21 and the nut 50 is the above-described embodiment. Is the same. In the fourth embodiment, the reduced diameter portion 39e is not formed on the base portion 39c of the cored bar 39a fitted on the output shaft 32. In the modified example, the reduced diameter portion 39e is formed.

  In the fourth embodiment and its modification, the radius r of the retaining ring insertion hole 20c on the inner diameter side of the bearing support member 20, the radial width L of the retaining ring 27, the outer periphery of the base portion 39c of the core metal 39a, or There is a relationship of (r−L <R) with the radius R of the outer periphery of the reduced diameter portion 39e formed in the base portion 39c.

  The relationship between the radius r of the retaining ring insertion hole 20c, the radial width L of the retaining ring 27, and the radius R of the outer periphery of the base portion 39c of the core metal 39a or the outer periphery of the reduced diameter portion 39e formed in the base portion 39c. By setting in this way, it is possible to determine whether the retaining ring 27 is assembled or not when the bearing support member 20 in which the second bearing 21 is fitted is assembled to the output shaft. That is, in FIG. 8 and FIG. 9, when the inner ring 21 b is tightened to the vehicle rear side by the nut 50 after the bearing support member 20 in which the second bearing 21 is fitted is fitted on the output shaft 32, the retaining ring 27 is If it is not locked in the annular groove 20a, which is a predetermined assembly position, the rear end surface in the vehicle axial direction of the outer ring 21a contacts the retaining ring 27, and it can be detected that the retaining ring 27 is incompletely assembled. Even if the retaining ring 27 is not completely assembled, the retaining ring 27 can finally fit into the annular groove 20a by tightening the nut 50. For this reason, even if the nut 50 is tightened, the incomplete assembly of the retaining ring 27 can be prevented from flowing out.

  On the other hand, if the retaining ring 27 is properly assembled in the annular groove 20a, the bearing 21 in the vehicle axial direction rear end surface of the inner ring 21b is in the vehicle axial direction of the base portion 39c of the cored bar 39a or the reduced diameter portion 39e of the base portion 39c. It can be tightened until it comes into contact with the front end surface, that is, to a predetermined tightening position.

  Thus, the radius r of the retaining ring insertion hole 20c of the bearing support member 20, the radial width L of the retaining ring 27, and the reduced diameter portion 39e formed on the outer periphery or the base portion 39c of the base portion 39c of the cored bar 39a. (R−L <R) with the relationship between the outer peripheral radius R and the base portion of the retaining ring 27 and the cored bar 39a when the bearing support member 20 fitted with the second bearing 21 is assembled to the output shaft 32. Since 39c contacts, it can be judged whether the retaining ring 27 is assembled in the assembling process.

  Also, the fourth embodiment and the first to third embodiments described above can be combined. For example, in the combination of the first embodiment and the fourth embodiment, the relationship of the radial gap between the retaining ring 27 and the cored bar 39a is (G1 <G2), and the bearing support member 20 is used for inserting the retaining ring. The relationship between the radius r of the hole 20c, the radial width L of the retaining ring 27, and the radius R of the outer periphery of the base portion 39c of the metal core 39a or the outer periphery of the reduced diameter portion 39e formed in the base portion 39c is (r−L <R). In this case, the effects of both the first and fourth embodiments are obtained. In the case of the combination of the second embodiment and the fourth embodiment, the combination of the third embodiment and the fourth embodiment also has the effects of the respective embodiments.

  FIG. 10 shows a fifth embodiment of the present invention. In the fifth embodiment, a steering shaft 102 is rotatably supported in a column tube 100 by a bearing (not shown).

  A power assist mechanism is provided on the front side of the column tube 100 in the vehicle. The housing of the power assist mechanism portion includes a gear housing 124 on the vehicle rear side and a cover 114 fixed to the vehicle housing on the vehicle front side.

  The gear housing 124 accommodates a torque sensor portion 103 (to be described later) in the vehicle rear side axially extending portion 113a.

  The gear housing 124 stores a speed reducing portion in a space formed with the cover 114 on the front side of the vehicle as will be described later.

  A shaft member 131 on the steering wheel (not shown) side extends into the gear housing 124 on the front side of the vehicle and serves as an input shaft of the power assist mechanism (hereinafter, the shaft member 131 is referred to as an input shaft). To do).

  A first rolling bearing 118 and a second rolling bearing 121 are provided on the inner diameter side of the substantially middle portion of the gear housing 124 and the bearing support member 120 formed on the inner diameter portion of the cover 114, respectively. An output shaft 132 of the power assist mechanism is supported on the gear housing 124 coaxially with the input shaft 131 via rolling bearings 118 and 121. The output shaft 132 has a rear end portion of the vehicle that extends rearward in the axially extending portion 113a of the gear housing 124 and faces the end surface of the front end portion of the input shaft 131.

  The base end of the torsion bar 133 is press-fitted and fixed to the vehicle front side enlarged diameter end portion 131c of the input shaft 131, and the torsion bar 133 extends inside the output shaft 132 formed in a hollow shape. The tip is fixed to the end of the output shaft 132 by a fixing pin 105a. An intermediate shaft (not shown) is connected to the vehicle front side of the output shaft 132 via a universal joint (not shown). The vehicle front side of the output shaft 132 is connected to the steered wheels via a universal joint (not shown), an intermediate shaft (not shown), a rack and pinion mechanism (not shown), and the like.

  A worm wheel 139 meshing with a worm 138 attached to the shaft of the electric motor 123 is fixed to the output shaft 132. The worm wheel 139 includes a metal core 139a that is externally fixed to the output shaft 132, and resin gear teeth 139b that are formed on the metal core 139a.

  In the present embodiment, the torque sensor unit 103, the speed reduction unit, the input / output shafts 131 and 132, and the electric motor 123 are integrally configured to form a unit unit 125.

  The worm 138 and the worm wheel 139 are housed in a gear housing 124 and a bearing support member 120 press-fitted and fitted into the gear housing 124. That is, the bearing support member 120 is supported by the gear housing 124 so as not to move in the axial direction and the radial direction.

  The output shaft 132 is pivotally supported by a first bearing 118 interposed on the inner wall of the gear housing 124 and a second bearing 121 fitted on the inner peripheral surface of the bearing support member 120. In the second bearing 121, the vehicle axial rear end surface of the inner ring 121 b is in contact with the vehicle axial front end surface of the base portion 139 c formed on the core metal 139 a of the worm wheel 139. 139c, the output shaft 132, and the inner ring 121b are fixed so as to be integrally rotatable.

  The second bearing 121 has an outer ring 121 a that is press-fitted into the inner peripheral surface of the bearing support member 120 and is locked by a retaining ring 127 that is hooked into an annular groove 120 a provided on the inner peripheral surface of the bearing support member 120. Then, the inner ring 121b is pressed against the end surface 132a of the enlarged diameter portion of the output shaft 132 via the core bar 139a by the nut 150 screwed to the output shaft 132, so that the bearing support member 120 is axially moved in the axial direction of the output shaft 132. Fixed in a stationary state.

  The structure of the A part shown in FIG. 10 can be directly replaced with the structure of each embodiment described with reference to FIGS.

  Next, with reference to FIGS. 11 to 18, sixth to tenth embodiments of the present invention will be described. The embodiment shown in FIG. 11 and subsequent figures is different from the above-described embodiment in that, in the above-described embodiment, the retaining ring 27 or 127 is arranged on the rear side in the vehicle axial direction of the second bearing 21 or 121. 11 to 18, the retaining ring 227 or 327 is arranged on the front side in the vehicle axial direction of the second bearing 221 or 321.

  This will be described in detail below with reference to FIG.

  FIG. 11 is an axial sectional view showing a pinion assist type electric power steering apparatus according to a sixth embodiment of the present invention, and FIG. 12 is a partially enlarged view showing a portion A of FIG.

  As shown in FIG. 11, the torsion bar 233 extends inside the hollow input shaft 231, and its proximal end is press-fitted into the output shaft 232, and the distal end is fixed to the input shaft 231 by the fixing pin 234. It is fixed to the end of the.

  A torque sensor unit 203 is provided around the input shaft 231. That is, detection grooves 235 of the torque sensor unit 203 are formed on the vehicle front side of the input shaft 231 (the lower side in FIG. 11), and the torque sensor unit 203 is formed radially outward of these grooves 235. The sleeve 236 is disposed. The sleeve 236 is fixed to the output shaft 232 by caulking or the like. A coil 237, a circuit board, and the like are provided outside the sleeve 236 in the radial direction. In the sleeve 236, a plurality of rectangular windows 236b extending in the axial direction facing the detection groove 235 are formed at equal intervals.

  A worm wheel 239 that meshes with a worm 238 attached to the shaft of the electric motor 223 is fixed to the output shaft 232. The worm wheel 239 includes a metal core 239a that is externally fixed to the output shaft 232, and resin gear teeth 239b that are formed on the metal core 239a.

  In the present embodiment, the torque sensor unit 203, the speed reduction unit including the input / output shafts 231 and 232, and the electric motor 223 form a unit unit 225 and are detachably attached to a rack housing (not shown).

  The worm 238 and the worm wheel 239 are accommodated in a gear housing 224 and a bearing support member 220 formed integrally with the gear housing 224. The gear housing 224 is integrally formed with a sensor housing 224b extending rearward of the vehicle (upward in FIG. 3).

  The input shaft 231 of the unit portion 225 is pivotally supported by a first bearing 218 interposed on the inner wall of the sensor housing 224b, and the output shaft 232 is a second bearing 221 that is fitted on the inner peripheral surface of the annular bearing support member 220. It is supported by. In the second bearing 221, the vehicle axial rear end surface of the inner ring 221 b is in contact with the vehicle axial front end surface of the base portion 239 c formed on the metal core 239 a of the worm wheel 239. 239c, the output shaft 232, and the inner ring 221b are fixed so as to be integrally rotatable.

  As shown in an enlarged view in FIG. 12, the second bearing 221 is press-fitted to the stepped portion 220 b formed on the inner peripheral surface of the bearing support member 220 at the rear end surface in the vehicle axial direction of the outer ring 221 a, and the front end surface in the vehicle axial direction. Is locked by a retaining ring 227 that is latched in an annular groove 220 a provided in the bearing support member 220, and the inner ring 221 b is tightened in the axial direction by a nut 250 that is screwed to the output shaft 232, whereby the bearing support member 220. On the other hand, the output shaft 232 is fixed in a fixed state in the axial direction. The inner periphery of the retaining ring 227 is opposed to the outer periphery of the nut 250 screwed to the output shaft 232 in the radial direction.

  As shown in FIG. 12, the inner ring dimension of the retaining ring 227 is formed by the difference between the inner diameter dimension of the retaining ring 227 and the outer diameter dimension of the nut 250 screwed into the output shaft 232. The dimension in the radial direction of the gap G1 between the circumference and the outer circumference of the nut 250 is set to be smaller than the radial length G2 of the engagement margin with respect to the annular groove 220a of the retaining ring 227 (G1 <G2).

  In the above configuration, as shown in FIG. 12, the radial dimension of the gap G1 between the inner periphery of the retaining ring 227 and the outer periphery of the nut 250 is the radial length G2 of the engagement margin with respect to the annular groove 220a of the retaining ring 227. Since it is set to be smaller, when an unexpected load is applied to the retaining ring 227, even if the retaining ring 227 is displaced in the axial direction, the engagement margin of the retaining ring 227 is not released from the annular groove 220a. Absent. Even if the retaining ring 227 is displaced in the axial direction and the inner periphery of the retaining ring 227 comes into contact with the outer periphery of the nut 250, it can return to a predetermined position when a reverse load is applied. Therefore, the retaining ring 227 is not completely detached from the annular groove 220a. Therefore, it is possible to prevent the output shaft 232 from becoming loose and developing into a serious failure.

  Thus, since the dimension in the radial direction of the gap G1 between the retaining ring 227 and the nut 250 is set to be relatively small, when the bearing support member 220 with the second bearing 221 fitted therein is assembled to the output shaft 232, If the retaining ring 227 is not assembled at an appropriate position, the retaining ring 227 and the nut 250 are easily brought into contact with each other. Therefore, in the assembly process, it can be determined whether the retaining ring 227 is assembled properly. Therefore, it is possible to double check the check when assembling the retaining ring 227 and the check after assembling.

  FIG. 13 shows a first modification of the sixth embodiment. In the first modification, the outer periphery of the rear end portion of the nut 250 in the vehicle axial direction forms a reduced diameter portion 250e. In the present modification, the shape and configuration of the bearing support member 220 are the same as those of the sixth embodiment of FIG. 12, and the bearing ring 227 and the nut 250 are latched by the annular groove 220a formed on the inner periphery. Two bearings 221 are supported in the axial direction. The inner periphery of the retaining ring 227 is opposed to the outer periphery of the reduced diameter portion 250e of the nut 250 screwed to the output shaft 232 in the radial direction.

  In this modification, the gap G1 between the retaining ring 227 and the nut 250 is between the inner periphery of the retaining ring 227 and the outer periphery of the reduced diameter portion 250e of the nut 250 (the clearance in the radial direction between the retaining ring 27 and the nut 50). G1) <(the radial length G2 of the hooking allowance of the retaining ring 27 with respect to the annular groove 20a).

  Since the retaining ring 227 is arranged in this way, this modification has the same effect as the first modification of the first embodiment.

  FIG. 14 shows only a part different from the sixth embodiment (that is, a part corresponding to part A in FIG. 11) in the seventh embodiment of the present invention. In the seventh embodiment, a part shown in FIG. 14 different from the sixth embodiment will be described.

  Also in the seventh embodiment, the arrangement of the constituent members of the input shaft 231, the output shaft 232, the cored bar 239a, the retaining ring 227, the second bearing 221 and the nut 250 is the same as that of the sixth embodiment. In the seventh embodiment, the rear end portion of the nut 250 in the vehicle axial direction is the reduced diameter portion 250e as in the modification of the sixth embodiment shown in FIG. 13, and the inner periphery of the retaining ring 227 is the reduced diameter portion. Opposite to the outer periphery of 250e in the radial direction.

  The seventh embodiment is different from the sixth embodiment in the arrangement state of the retaining ring 227.

  In the seventh embodiment, as shown in FIG. 14, the axial direction of the gap G3 formed by the vehicle axial direction front end surface of the retaining ring 227 and the vehicle axial direction rear end surface 250d of the nut 250 screwed to the output shaft 232 The dimension is set to be smaller than the axial length G4 of the hooking allowance with respect to the annular groove 220a of the retaining ring 227 (G3 <G4).

  In the above configuration, as shown in FIG. 14, the axial dimension of the gap G3 between the front end surface in the vehicle axial direction of the retaining ring 227 and the end surface 250d on the vehicle rear side of the nut 250 is set as the engagement allowance for the annular groove 220a of the retaining ring 227. Is set to be smaller than the axial length G4, and when an unexpected load is applied to the retaining ring 227, even if the retaining ring 227 is displaced in the axial direction, the engagement allowance is removed from the annular groove 220a. There is nothing. Even if the retaining ring 227 is displaced in the axial direction, it is possible to return to a predetermined position when a load in the opposite direction is applied, so that the retaining ring 227 is completely detached from the annular groove 220a, It is possible to prevent the output shaft 232 from becoming loose and developing into a serious failure.

  As described above, the axial dimension of the gap G3 between the retaining ring 227 and the nut 250 is set to be relatively small, and the retaining ring 227 and the nut 250 are easily in contact with each other. When the bearing support member 220 is assembled to the output shaft 232, the retaining ring 227 and the nut 250 come into contact with each other unless the retaining ring 227 is assembled at an appropriate position. Judgment can be made. Therefore, a double check can be performed at the time of assembling the retaining ring 227 and after the assembling.

  FIG. 15 shows an eighth embodiment of the present invention. Also in the eighth embodiment, the arrangement of the constituent members of the input shaft 231, the output shaft 232, the core metal 239a, the retaining ring 227, the second bearing 221 and the nut 250 is the same as in the sixth and seventh embodiments.

  The eighth embodiment includes both characteristic configurations of the sixth embodiment and the seventh embodiment. That is, in the eighth embodiment, the radial clearance relationship (G1 <G2) between the retaining ring 227 and the nut 250 is the same as that in the sixth embodiment, and the axial clearance between the retaining ring 227 and the nut 250 is the same. (G3 <G4) is the same as that in the seventh embodiment. Therefore, the eighth embodiment has the effects of both the sixth and seventh embodiments.

  FIG. 16 shows a ninth embodiment of the present invention, and FIG. 17 shows a modification of the ninth embodiment, in which the bearing support member 220 having the second bearing 221 fitted therein is assembled to the output shaft 232. The inside state is shown.

  In the ninth embodiment and its modification shown in FIGS. 16 and 17, the arrangement of the constituent members of the input shaft 231, the output shaft 232, the cored bar 239a, the retaining ring 227, the second bearing 221 and the nut 250 is the same as that described above. To the eighth embodiment. In the ninth embodiment and modifications thereof, the radius r of the retaining ring insertion hole 220c on the inner peripheral side of the bearing support member 220, the radial width L of the retaining ring 227, the outer periphery of the nut 250, or the nut 250 There is a relationship of (r−L <R) between the radius R of the outer periphery of the reduced diameter portion 250e formed at the vehicle rear side end.

  The relationship between the radius r of the retaining ring insertion hole 220c, the radial width L of the retaining ring 227, and the radius R of the outer periphery of the nut 250 or the outer periphery of the reduced diameter portion 250e formed on the nut 250 is set in this way. Thus, when the bearing support member 220 fitted with the second bearing 221 is assembled to the output shaft 232, it is possible to determine whether the retaining ring 227 is assembled or not. That is, in FIGS. 16 and 17, after the bearing support member 220 in which the second bearing 221 is fitted is fitted on the output shaft 232, the nut 250 is tightened toward the rear of the vehicle in the axial direction. If it is not assembled in the annular groove 220a, which is the assembly position, it is possible to detect that the vehicle rear side end surface of the nut 250 contacts the retaining ring 227 and that the retaining ring 227 is incompletely assembled. Even if the retaining ring 227 is not completely assembled, the retaining ring 227 can finally fit into the annular groove 220a by tightening the nut 250. For this reason, the outflow of incomplete assembly of the retaining ring 227 can be prevented even in the tightening process of the nut 250.

  On the other hand, if the retaining ring 227 is properly assembled in the annular groove 220a, the bearing 221 is tightened until the front end surface of the inner ring 221b in the vehicle axial direction contacts the rear end surface of the nut 250 in the vehicle axial direction. Can be tightened to position. (See FIGS. 12 and 13).

  Thus, the radius r of the retaining ring insertion hole 220c of the bearing support member 220, the radial width L of the retaining ring 227, and the radius R of the outer periphery of the nut 250 or the outer periphery of the reduced diameter portion 250e formed on the nut 250. (R−L <R), the retaining ring 227 and the nut 250 come into contact with each other when the bearing support member 232 fitted with the second bearing 221 is assembled to the output shaft 232. The quality of the assembled state of the retaining ring 227 can be determined.

  Further, the ninth embodiment and the sixth to eighth embodiments described above can be combined. For example, in the combination of the sixth embodiment and the ninth embodiment, the relationship of the radial gap between the retaining ring 227 and the cored bar 239a is (G1 <G2), and the retaining ring insertion hole of the bearing support member 220 The relationship between the radius r of 220c, the radial width L of the retaining ring 227, and the radius R of the outer periphery of the nut 250 or the outer periphery of the reduced diameter portion 250e formed on the nut 250 is (r−L <R). . In this case, the effects of both the sixth and ninth embodiments are obtained. In the case of the combination of the seventh embodiment and the ninth embodiment, the combination of the sixth embodiment and the ninth embodiment also has the effects of the respective embodiments.

FIG. 18 shows a tenth embodiment of the present invention.
In the tenth embodiment, a steering shaft 302 is rotatably supported in a column tube 300 by a bearing (not shown).

  A power assist mechanism is provided on the front side of the column tube 300 in the vehicle. The housing of the power assist mechanism section includes a gear housing 324 on the vehicle rear side and a cover 314 fixed to the vehicle housing on the vehicle front side.

  The gear housing 324 accommodates a torque sensor portion 303, which will be described later, in a vehicle rear side axially extending portion 313a.

  The gear housing 324 stores a speed reducing portion in a space formed with the cover 314 on the front side of the vehicle as will be described later.

  A shaft member 331 on the steering wheel (not shown) side extends into the gear housing 324 on the front side of the vehicle and serves as an input shaft for the power assist mechanism (hereinafter, the shaft member 331 is referred to as an input shaft). To do).

  A first rolling bearing 318 and a second rolling bearing 321 are provided on a bearing support member 320 formed on the inner diameter side of the substantially intermediate portion in the axial direction of the gear housing 324 and the inner diameter portion of the cover 314, respectively. The output shaft 332 of the power assist mechanism is supported on the gear housing 324 coaxially with the input shaft 331 via the rolling bearings 318 and 321. The output shaft 332 has a rear end of the vehicle that extends rearward in the axially extending portion 313 a of the gear housing 324 and faces the end surface of the input end of the input shaft 331.

  The base end of the torsion bar 333 is press-fitted and fixed to the vehicle front side enlarged diameter end portion 331c of the input shaft 331. The torsion bar 333 extends inside the hollow output shaft 332, and The tip is fixed to the end of the output shaft 332 by a fixing pin 305a. An intermediate shaft (not shown) is connected to the front side of the output shaft 332 via a universal joint (not shown). The vehicle front side of the output shaft 332 is connected to the steered wheels via a universal joint (not shown), an intermediate shaft (not shown), a rack and pinion mechanism (not shown), and the like.

  A worm wheel 339 engaged with a worm 338 attached to the shaft of the electric motor 323 is fixed to the output shaft 332. The worm wheel 339 includes a metal core 339a that is externally fixed to the output shaft 332, and resin gear teeth 339b that are formed on the metal core 339a.

  In the present embodiment, the torque sensor unit 303, the speed reduction unit, the input / output shafts 331 and 332, and the electric motor 323 are integrally configured to form a unit unit 325.

  The worm 338 and the worm wheel 339 are housed in a gear housing 324 and a bearing support member 320 that is press-fitted and fitted into the gear housing 324. That is, the bearing support member 320 is supported by the gear housing 324 so as not to move in the axial direction and the radial direction.

  The output shaft 332 is pivotally supported by a first bearing 318 interposed on the inner wall of the gear housing 324 and a second bearing 321 fitted inside the inner peripheral surface of the bearing support member 320. In the second bearing 321, the rear end surface in the vehicle axial direction of the inner ring 321 b is in contact with the front end surface in the vehicle axial direction of the base portion 339 c formed on the core metal 339 a of the worm wheel 339. 339c, the output shaft 332, and the inner ring 321b are fixed so as to be integrally rotatable.

  The second bearing 321 has an outer ring 321 a that is press-fitted into the inner peripheral surface of the bearing support member 320 and is locked by a retaining ring 327 that is hooked into an annular groove 320 a provided on the inner peripheral surface of the bearing support member 320. The inner ring 321b is pressed against the bearing support member 320 in the axial direction of the output shaft 332 by being pressed against the side surface 320b of the enlarged diameter portion of the output shaft 332 via the core bar 339a by the nut 350 screwed to the output shaft 332. Fixed in a stationary state.

  The structure of the portion A shown in FIG. 18 can be replaced as it is with the structure of each embodiment described with reference to FIGS.

  As described above, the present invention can be applied to various types of electric power steering devices, and is not limited to the above embodiments and modifications.

  In each of the above-described embodiments and modifications, the method of setting the size of the radial gap G1 between the retaining ring and the core metal of the worm wheel and the radial length G2 of the engagement margin with respect to the annular groove of the retaining ring is as follows. The clearance G1 can be set smaller by making the inner diameter of the retaining ring smaller while keeping the length G2 of the hanging allowance unchanged. However, the present invention is not limited to this method, and the gap G1 can be set to be larger while the gap G1 is left as it is.

  In the latter case, it is necessary to make the outer diameter of the retaining ring engaging margin larger and to form a deep annular groove by the bearing support member, which changes two parts, so the gap G1 is made smaller. The change process will increase more than the case. In consideration of such points, an optimum method can be appropriately selected according to circumstances.

1 is an overall schematic configuration diagram showing a pinion assist type electric power steering apparatus. It is a fragmentary sectional view which shows the unit part and rack housing of the electric power steering apparatus of FIG. 1 is an axial cross-sectional view showing a pinion assist type electric power steering device according to a first embodiment of the present invention. FIG. 4 is a partially enlarged view showing a portion A in FIG. 3. FIG. 5 is an enlarged view of a portion corresponding to a portion A in FIG. 3, showing a pinion assist type electric power steering device according to a modification of the first embodiment of the present invention. FIG. 4 is an enlarged view of a portion corresponding to a portion A in FIG. 3, showing a pinion assist type electric power steering device according to a second embodiment of the present invention. FIG. 5 is an enlarged view of a portion corresponding to a portion A in FIG. 3, showing a pinion assist type electric power steering device according to a third embodiment of the present invention. FIG. 7 is an enlarged view of a portion corresponding to a portion A in FIG. 3, showing a pinion assist type electric power steering device according to a fourth embodiment of the present invention. FIG. 10 is an enlarged view of a portion corresponding to a portion A in FIG. 3, showing a pinion assist type electric power steering device according to a modification of the fourth embodiment of the present invention. It is an axial direction sectional view showing a column assist type electric power steering device concerning a 5th embodiment of the present invention. It is an axial direction sectional view showing a pinion assist type electric power steering device concerning a 6th embodiment of the present invention. It is the elements on larger scale which show A part in FIG. FIG. 12 is an enlarged view of a portion corresponding to a portion A in FIG. 11, showing a pinion assist type electric power steering device according to a modification of the sixth embodiment of the present invention. FIG. 12 is an enlarged view of a portion corresponding to a portion A in FIG. 11, showing a pinion assist type electric power steering apparatus according to a seventh embodiment of the present invention. FIG. 12 is an enlarged view of a portion corresponding to a portion A in FIG. 11, showing a pinion assist type electric power steering device according to an eighth embodiment of the present invention. FIG. 12 is an enlarged view of a portion corresponding to a portion A in FIG. 11, showing a pinion assist type electric power steering device according to a ninth embodiment of the present invention. FIG. 12 is an enlarged view of a portion corresponding to a portion A in FIG. 11, showing a pinion assist type electric power steering device according to a modification of the ninth embodiment of the present invention. It is an axial direction sectional view showing the column assist type electric power steering device concerning a 10th embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering wheel 2, 102, 302 Steering shaft 2a Upper shaft 2b Lower shaft 3, 103, 203, 303 Torque sensor part 4, 5 Universal joint 8 Rack housing 9, 10 Tie rod 13 Controller (control part)
14 Ignition switch 15a, 15b Fuse 16 Battery 17 Vehicle speed sensor 18, 118, 228, 318 First bearing 20, 120, 220, 320 Bearing support member 20a, 120a, 220a, 320a Annular groove 20b, 120b, 220b, 320b Stepped part 20c, 220c Retaining ring insertion hole 21, 121, 221, 321 Second bearing 21a, 121a, 221a, 321a Outer ring 21b, 121b, 221b, 321b Inner ring 22 Rack shaft 23, 123, 223, 323 Motor 24, 124, 224 324 Gear housing 24b, 224b Sensor housing 25, 125, 225, 325 Unit part 27, 127, 227, 327 Retaining ring 30, 230 Pinion 31, 131, 231, 331 Input shaft 32, 132, 232 332 Output shaft 32a, 132a, 232a, 332a End face of expanded diameter portion 33, 133, 233, 333 Torsion bar 35, 235 Detection groove 36, 136, 236, 336 Sleeve 37 237 Coil 38, 138, 238, 338 Warm 39 139, 239, 339 Worm wheel 39a, 139a, 239a, 339a Core metal 39b, 139b, 239b, 339b Gear teeth 39c, 139c, 239c, 339c Base portion 39e Reduced diameter portion 50 150 250 250 350 Nut 113a, 313a Extension portion 114 314 Cover 250e Reduced diameter part

Claims (5)

A torque sensor detects a steering torque applied to the steering wheel, and includes a deceleration unit that transmits auxiliary steering torque generated from the electric motor in response to the detected steering torque to the output shaft of the steering mechanism,
A bearing that supports the output shaft is fitted into a bearing support member,
The bearing is axially formed by a ring-shaped retaining ring that is latched by an annular groove formed on the inner periphery of the bearing support member, and a member that is externally fitted to the output shaft and is separate from the retaining ring. In the electric power steering device fixedly fixed to
The inner circumference of the retaining ring, the inner circumference and the diameter of the retaining ring, which are formed by the difference between the inner diameter dimension of the retaining ring and the outer diameter dimension of the output shaft or the other member fitted on the output shaft. The radial dimension of the gap between the output shaft facing in the direction or the outer periphery of the other member fitted on the output shaft is set to be smaller than the radial length of the retaining margin with respect to the annular groove of the retaining ring. An electric power steering device. A torque sensor detects a steering torque applied to the steering wheel, and includes a deceleration unit that transmits auxiliary steering torque generated from the electric motor in response to the detected steering torque to the output shaft of the steering mechanism,
A bearing that supports the output shaft is fitted into a bearing support member,
The bearing is axially formed by a ring-shaped retaining ring that is latched by an annular groove formed on the inner periphery of the bearing support member, and a member that is externally fitted to the output shaft and is separate from the retaining ring. In the electric power steering device fixedly fixed to
A shaft of a gap formed by an end surface on one side in the axial direction of the retaining ring and an end surface of the separate member that is externally fitted to the output shaft and that is opposed to the end surface on the one side of the retaining ring in the axial direction. The electric power steering device is characterized in that a direction dimension is set to be smaller than an axial length of a hooking allowance of the retaining ring with respect to the annular groove. A torque sensor detects a steering torque applied to the steering wheel, and includes a deceleration unit that transmits auxiliary steering torque generated from the electric motor in response to the detected steering torque to the output shaft of the steering mechanism,
A bearing that supports the output shaft is fitted into a bearing support member,
The bearing is axially formed by a ring-shaped retaining ring that is latched by an annular groove formed on the inner periphery of the bearing support member, and a member that is externally fitted to the output shaft and is separate from the retaining ring. In the electric power steering device fixedly fixed to
The inner circumference of the retaining ring, the inner circumference and the diameter of the retaining ring, which are formed by the difference between the inner diameter dimension of the retaining ring and the outer diameter dimension of the output shaft or the other member fitted on the output shaft. The radial dimension of the gap between the output shaft facing in the direction or the outer periphery of the other member fitted on the output shaft is set to be smaller than the radial length of the retaining margin with respect to the annular groove of the retaining ring. And an end face on one side in the axial direction of the retaining ring, and an end face of the separate member that is externally fitted to the output shaft, facing the end face on the one side of the retaining ring in the axial direction. The electric power steering device is characterized in that the axial dimension of the gap is set smaller than the axial length of the hooking allowance of the retaining ring with respect to the annular groove. A torque sensor detects a steering torque applied to the steering wheel, and includes a deceleration unit that transmits auxiliary steering torque generated from the electric motor in response to the detected steering torque to the output shaft of the steering mechanism,
A bearing that supports the output shaft is fitted into a bearing support member,
The bearing is axially formed by a ring-shaped retaining ring that is latched by an annular groove formed on the inner periphery of the bearing support member, and a member that is externally fitted to the output shaft and is separate from the retaining ring. In the electric power steering device fixedly fixed to
A radius r of a retaining ring insertion hole formed in the bearing support member, a radial width L of the retaining ring, and an inner circumference and a diameter of the separate member that are externally fitted to the output shaft. An electric power steering device characterized in that a relationship with a radius R of an outer periphery facing in a direction is r−L <R. A torque sensor detects a steering torque applied to the steering wheel, and includes a deceleration unit that transmits auxiliary steering torque generated from the electric motor in response to the detected steering torque to the output shaft of the steering mechanism,
A bearing that supports the output shaft is fitted into a bearing support member,
The bearing is axially formed by a ring-shaped retaining ring that is latched by an annular groove formed on the inner periphery of the bearing support member, and a member that is externally fitted to the output shaft and is separate from the retaining ring. In the electric power steering device fixedly fixed to
A radius r of a retaining ring insertion hole formed in the bearing support member, a radial width L of the retaining ring, and an inner circumference and a diameter of the separate member that are externally fitted to the output shaft. The electric power steering apparatus according to any one of claims 1 to 3, wherein a relationship with a radius R of an outer periphery facing in a direction is r-L <R.

Images