JP4799019B2 - Power steering apparatus and assembling method thereof - Google Patents

Description

  The present invention relates to a power steering apparatus including an assembly in which an input shaft to which a steering force from a handle is transmitted and an output shaft coupled to the input shaft via a torsion bar are integrated, and an assembling method thereof.

  In a power steering apparatus, an input shaft to which a steering force from a steering wheel is input is coupled to an output shaft through a torsion bar, and a steering torque detected by an actuator (for example, an electric motor) based on a twist amount of the torsion bar. Auxiliary steering force according to the is generated. At this time, the relative positions of the input shaft and the output shaft integrated via the torsion bar in the direction of the rotation center line occupy a neutral position where the torque sensor for detecting the steering torque generates a detection signal serving as a reference point. The input shaft and the output shaft at the set relative position are integrated and assembled to the housing.

For example, in the electric power steering apparatus disclosed in Patent Document 1, a subassembly in which an input shaft, an output shaft, a torsion bar, a steering torque detecting means, and a worm wheel are assembled is inserted into a housing as one unit. Next, the output shaft and the bearing are set by the lock nut inserted from the opening at the lower end of the housing, and the output shaft is supported on the housing via the bearing. In the subassembly, the torsion bar is connected to the input shaft and the output shaft by pins, and the steering torque detecting means is attached to the input shaft by bolts.
JP-A-9-309447

  By the way, when assembling an assembly in which the input shaft and the output shaft are integrated into the housing, the assembly is pressed when the bearing held by the output shaft is press-fitted into the housing, or when the output shaft is press-fitted into the bearing held by the housing. It is necessary to apply a press-fitting load in the press-fitting direction. In that case, when a press-fit load is applied to the input shaft, the relative position of the input shaft and the output shaft may deviate from the set position. In this case, the relative position needs to be adjusted so that the torque sensor occupies the neutral position, and the work efficiency of the assembly of the power steering device is lowered.

  The present invention has been made in view of such circumstances, and the relative position of the input shaft and the output shaft is set from a predetermined relative position when the assembly in which the input shaft and the output shaft are integrated is assembled to the housing. It is an object of the present invention to provide a power steering device and an assembling method thereof that are prevented from shifting and that can improve the work efficiency of assembly.

  According to a first aspect of the present invention, there is provided an assembly in which an input shaft to which a steering force from a steering wheel is input and an output shaft coupled to the input shaft via a torsion bar are integrated, and the assembly is output to the output shaft. A housing that is rotatably supported by a shaft; and a torque sensor that detects a steering torque based on a torsion amount of the torsion bar; and a predetermined amount between the input shaft and the output shaft set in the assembly In a power steering apparatus in which a reference position of the torque sensor is set corresponding to a relative position, the assembly is inserted in the press-fitting direction on the output shaft in order to press-fit the assembly into an assembly position in the housing. It is a power steering device provided with an engaging portion that can engage a tool to be moved.

  According to this, since the press-fitting load is applied to the output shaft through the engaging portion when the assembly is press-fitted into the housing, the relative positions of the input shaft, the torsion bar, and the output shaft may change due to the press-fitting load. In addition, when the assembly of the assembly is completed, the predetermined relative positions of the input shaft and the output shaft set in the state of the assembly are maintained, so that the torque sensor occupies the reference position after the assembly of the assembly is completed. Thus, there is no need to adjust the relative positions of the input shaft and the output shaft.

  According to a second aspect of the present invention, in the power steering device according to the first aspect, the assembly is press-fitted into the housing via a bearing held by the output shaft or a bearing held by the output shaft. The housing is provided with an opening on the extension of the output shaft in the assembly direction, and the engaging portion is opposite to the side on which the input shaft is located in the rotation center line direction of the output shaft. At the end of the housing, the assembly is provided at a position that does not protrude from the opening to the outside of the housing in a state immediately before being pressed into the bearing or the housing.

  According to this, since the engaging portion is at the end of the output shaft opposite to the input shaft, the press-fitting operation can be performed without being obstructed by the input shaft. In addition, a press-fitting load can be applied to the engaging portion by inserting a tool into the housing through the opening in the engaging portion located in the housing at the position of the assembly just before the press-fitting into the housing. In order to apply the press-fit load, it is not necessary to position the engaging portion outside the housing.

  According to a third aspect of the present invention, in the power steering device according to the second aspect, the end portion includes a journal portion supported by another bearing held by the housing, and the another bearing is connected to the rotation center line. And a screw portion into which a lock nut fixed in a direction is screwed, and the engagement portion is located closer to the tip of the end portion than the screw portion.

  According to this, since the tool engages with the engaging portion closer to the tip than the screw portion, the thread of the screw portion is crushed by the tool, unlike when a press-fitting load is applied while the screw portion is sandwiched by the tool. It will not be.

According to a fourth aspect of the present invention, there is provided an assembly in which an input shaft to which a steering force from a steering wheel is input and an output shaft coupled to the input shaft via a torsion bar are integrated, and the assembly is output to the output shaft. and Ruha Ujingu be rotatably supported in the axial, on the basis of the torsion of the torsion bar and a detection to belt Rukusensa steering torque, and said output shaft and the input shaft which is set in the assembly In a method of assembling a power steering apparatus in which a reference position of the torque sensor is set corresponding to a predetermined relative position between the output shaft, a press-fit load in a direction of press- fitting the assembly into an assembly position in the housing , or by adding by press-fitting tool engagement portion constituting the assembly together is relatively immovably coupled to said output shaft, said assembly in said housing It is an assembly method of a power steering apparatus characterized by press-fitting the urging position.

  According to this, since the press-fitting load is applied to the output shaft or the component member when the assembly is press-fitted into the housing, the assembly is completed even when the assembly of the assembly is completed as in the first aspect of the invention. Since the predetermined relative position of the input shaft and output shaft set in the three-dimensional state is maintained, the relative position of the input shaft and output shaft should be adjusted so that the torque sensor occupies the reference position after assembly of the assembly is completed. There is no need to adjust.

  According to invention of Claim 1, the following effect is show | played. That is, the assembly of the assembly to the housing prevents the relative position of the input shaft and the output shaft from deviating from a predetermined relative position, and there is no need to adjust the relative position after the assembly is assembled. The work efficiency of assembling the apparatus is improved.

  According to invention of Claim 2, in addition to the effect of the invention of the cited claim, there exists the following effect. That is, the press-fitting work can be performed without being hindered by the input shaft, so that the press-fitting work is facilitated, and it is not necessary to position the engaging portion outside the housing before the press-fitting starts. An increase in size in the direction of the center line is suppressed.

  According to invention of Claim 3, in addition to the effect of the invention of the cited claim, there exist the following effects. That is, the thread of the thread portion is not crushed by the tool, and damage to the thread portion by the tool is prevented.

  According to the fourth aspect of the invention, the same effect as that of the first aspect of the invention can be achieved.

Embodiments of the present invention will be described below with reference to FIGS.
Referring to FIG. 1, a power steering device 1 to which the present invention is applied includes a gear box 3 into which a steering force applied to a steering wheel 2 by a driver is input via an interlocking mechanism (not shown), and a gear box 3. A transmission mechanism having a pair of tie rods 4a and 4b for transmitting the output steering force to the steering wheel, and an auxiliary steering force generation mechanism 5 having an electric motor 25 for generating an auxiliary steering force for reducing the steering force by the driver; A rack and pinion type electric power steering apparatus.

  The gear box 3 includes a housing 6 attached to the vehicle body, an input unit 10 having an input shaft 11 to which a steering force from the handle 2 is transmitted, and a steering force from the input unit 10 housed in the housing 6 to transmit the steering force. A rack and pinion mechanism including a rack shaft 22 that outputs to the mechanism.

  The housing 6 has a first end housing 7 as a first housing that rotatably supports the input shaft 11, and a cylinder having an end 9 a that is coupled to the end 7 b of the first end housing 7 in the axial direction. An intermediate housing 9 as a second housing having a cylindrical shape, and a second end housing 8 as a cylindrical third housing having an end 8 a coupled to another end 9 b of the intermediate housing 9. The rack shaft 22 is accommodated across the three housings 7-9.

Referring also to FIG. 2, the first end housing 7 includes a first housing portion 7 c having a cylindrical portion 7 e extending along the rack shaft 22, and a first housing portion 7 c coupled to the first housing portion 7 c by a bolt B 1. It is comprised from the 2nd housing part 7d which forms the storage chamber G in cooperation with the housing part 7c. The cylindrical tubular portion 7e has an end portion 7b and another end portion 7a to which a dustproof boot D that covers a joint portion between the end portion 22a of the rack shaft 22 and the tie rod 4a is attached. The second end housing 8 has an end portion 8a and another end portion 8b to which a dustproof boot D covering between the other end portion 22b of the rack shaft 22 and the tie rod 4b is attached. The intermediate housing 9 is constituted by a thin cylindrical member as compared with the cylindrical portion 7e and the cylindrical second end housing 8, and has a substantially uniform diameter small portion 9c having an end portion 9a, and an end portion. And a large-diameter portion 9d having an inner diameter and an outer diameter larger than the small-diameter portion 9c and a substantially uniform diameter.
The first housing portion 7c, the intermediate housing 9, and the second end housing 8 form an insertion hole H through which the rack shaft 22 is inserted. A pair of end openings Ha and Hb of the insertion hole H are formed in both end portions 7a and 8b, respectively.

  In the specification or claims, the axial direction, the radial direction, and the circumferential direction are respectively the direction in which the central axis L2 of the rack shaft 22 extends, the radial direction centered on the central axis L2, and the central axis L2. The cross section is a cross section in a plane perpendicular to the central axis L2.

  The input portion 10 is relatively connected to the input shaft 11 rotatably supported by the second housing portion 7d via a bearing 15 held by a torque sensor 14 to be described later, coaxially with the input shaft 11 and via a torsion bar 13. An output shaft 12 that is integrally coupled so as to be rotatable is provided, and a torque sensor 14 that detects a steering torque based on the amount of twist of the torsion bar 13. The output shaft 12 to which the torsion bar 13 is coupled at the serration portion 13a as the coupling portion is rotatably supported by the first housing portion 7c in the storage chamber G via bearings 16 and 17 comprising a pair of ball bearings. The

  Referring to FIGS. 2 and 3, the input shaft 11, the torsion bar 13 and the output shaft 12 together with the worm wheel 26b, the torque sensor 14 and the second housing part 7d, which will be described later, before being assembled to the first housing part 7c, A single assembly M is assembled and integrated in advance, and is assembled to the first housing portion 7c in the state of the assembly M. At this time, the torsion bar 13 is coupled to the input shaft 11 by a pin 18 as a coupling means, and is coupled to the output shaft 12 by press-fitting as a coupling means in a serration portion 13a provided in the torsion bar 13. In the assembly M, the relative positions of the input shaft 11, the torsion bar 13 and the output shaft 12 in the rotation center line direction A described later occupy a reference position where the torque sensor 14 generates a detection signal serving as a reference point. It is set at a predetermined relative position.

  The torque sensor 14 attached to the second housing portion 7d outside the storage chamber G is in proportion to the direction A of the rotation center line L1 of the input shaft 11 in proportion to the amount of twist of the torsion bar 13 (hereinafter referred to as “rotation center line direction A”). And a pair of coils 14b and 14c as a detector for detecting the position of the core 14a.

  More specifically, a cylindrical holder 14d that holds the core 14a is fitted to the input shaft 11 and the output shaft 12 so as to be movable parallel to the rotation center line direction A, and holds a pair of coils 14b and 14c. The sensor main body 14e to be fixed is fixed to the second housing part 7d by the bolt B2. A pin (not shown) that fits in a spiral groove (not shown) provided on the peripheral wall of the holder 14d is fixed to the input shaft 11, and the output shaft 12 is provided on the peripheral wall of the holder 14d. The pair of pins 14g are fixed so as to fit in the pair of guide grooves 14f and guide the holder 14d so as to be movable parallel to the rotation center line direction A.

Here, the predetermined relative position and the neutral position as the reference position set based on the position of the core 14a with respect to the pair of coils 14b and 14c are set as follows.
The input shaft 11 is inserted into a torsion bar 13 coupled to the output shaft 12, and is assembled to the output shaft 12 and the torsion bar 13 in a rotatable state. Next, after the input shaft 11 and the output shaft 12 are inserted into the second housing portion 7d, and the holder 14d is fitted to the input shaft 11 and the output shaft 12, the sensor is inserted into the input shaft 11 so as to cover the holder 14d. The main body 14e is coupled to the second housing part 7d by a bolt B2. In this state, the input shaft 11 is rotated with respect to the torsion bar 13, and the holder 14d is moved in the rotation center line direction A through the spiral groove, whereby the pair of coils 14b and 14c are rotated in the rotation center line direction A. The neutral position is determined by adjusting the position of the core 14a. The relative position of the input shaft 11 with respect to the output shaft 12 and the torsion bar 13 when this neutral position is obtained becomes the predetermined relative position. In this state, an insertion hole 11c aligned with an insertion hole 13c formed in advance in the torsion bar 13 is formed in the input shaft 11, and a pin 18 is press-fitted into the insertion holes 11c, 13c, whereby an assembly M is obtained. . Therefore, in the assembly M in which at least the input shaft 11, the output shaft 12, the torsion bar 13, and the torque sensor 14 are integrated, torque corresponding to the predetermined relative position between the input shaft 11 and the output shaft 12. The neutral position of the sensor 14 is set.

When the input shaft 11 and the output shaft 12 rotate relative to each other while twisting the torsion bar 13, the core 14a moves from the neutral position to the rotation center line direction A with respect to the input shaft 11 and the coils 14b and 14c. Due to the displacement, the inductances of the coils 14b and 14c change according to the relative displacement amount and the displacement direction, and the steering torque is detected based on the change in the inductance.
The torque sensor 14 is partially covered with a protective cover 19 (see FIG. 1) for preventing a collision with a foreign object during traveling of the vehicle.

  1 to 3, the rack and pinion mechanism includes a pinion 21 formed on the output shaft 12 and rotating integrally with the output shaft 12, and a rack shaft 22 formed with a rack portion 23 that meshes with the pinion 21. With. The pair of bearings 16 and 17 respectively support a pair of journal portions 12c and 12d provided at both end portions 12a and 12b located on the output shaft 12 with the pinion 21 in the rotation center line direction A, respectively. The rotation center line of the output shaft 12 and the pinion 21 coincides with the rotation center line L1.

  The first housing portion 7c is provided with an opening 70 in an end portion 7c2 opposite to the end portion 7c1 to which the second housing portion 7d is attached in the rotation center line direction A. The opening 70 is positioned on the extension of the output shaft 12 in the assembly direction of the output shaft 12 to the first housing portion 7c, and is closed by a plug 71 as a closing member that is screwed into and fixed to the end portion 7c2. . Here, the assembly direction is the same as the rotation center line direction A.

  Then, in the output shaft 12, the journal portion 12 d and the journal portion 12 d are arranged in order from the end near the pinion 21 on the end portion 12 b that is opposite to the side where the input shaft 11 is positioned in the rotation center line direction A and passes through the opening 70. A screw part 12e into which a lock nut 72, which is a screw part for fixing the bearing 17 different from the bearing 16 in the rotation center line direction A, and a tool 80 for moving the assembly M in the assembling direction are provided. Engaging portions 73 that can be engaged with each other are integrally formed on the output shaft 12. Therefore, the engaging portion 73 located closer to the tip of the output shaft 12 than the journal portion 12d and the screw portion 12e has an outer diameter smaller than the outer diameter of the journal portion 12d and the screw portion 12e, and at the tip of the output shaft 12. The large-diameter portion 73a, and the small-diameter portion 73b having an outer diameter smaller than that of the large-diameter portion 73a and positioned closer to the pinion 21. Further, the small-diameter portion 73b of the engaging portion 73 has a shape that is sandwiched by a tool 80 from a direction orthogonal to the press-fitting direction (corresponding to the assembly direction). In the sandwiched state, the output shaft 12 rotates. Be blocked.

  Referring to FIGS. 1 and 2, a rack shaft 22 that extends in the left-right direction in a state where the power steering device 1 is mounted on a vehicle has an outer peripheral surface that is substantially cylindrical except for the rack portion 23. The power steering device 1 is supported by the housing 6 so as to be capable of reciprocating in the axial direction by a support structure described later. The rack portion 23 having a tooth portion 23a formed in a notch portion in which a part of the rack shaft 22 is cut out in parallel with the central axis L2 over a predetermined range in the axial direction is the outer peripheral surface of the rack shaft 22. The rack 23 is pressed against the pinion 21 by a rack guide 31 that presses the rack 23 against the back 23b.

  The transmission mechanism includes a pair of tie rods 4a and 4b connected to both end portions 22a and 22b of the rack shaft 22 via ball joints 24a and 24b as coupling portions, and each tie rod 4a and 4b and a steering wheel. And a link mechanism (not shown) for connecting the two.

  The auxiliary steering force generating mechanism 5 that adds an auxiliary steering force to the rack shaft 22 at the time of turning is electrically operated as an actuator controlled by an electronic control unit (not shown) to which the steering torque detected by the torque sensor 14 is input. A motor 25 and a worm gear 26 as a transmission mechanism that transmits the rotational force of the electric motor 25 to the rack shaft 22 are provided. The worm gear 26 housed in the storage chamber G is coupled to the rotating shaft of the electric motor 25 attached to the first housing portion 7c and the rotating shaft of the electric motor 25. The worm gear 26 is coupled to the output shaft 12 and rotates together with the output shaft 12. Worm wheel 26b.

  Therefore, in the power steering apparatus 1, when the steering force applied by the driver to the steering wheel 2 to be steered is transmitted to the input shaft 11, the input shaft 11 causes the torsion bar 13 to twist and the output shaft 12 and The pinion 21 is rotated, and the rack shaft 22 driven by the pinion 21 moves in the axial direction. At the same time, the electric motor 25 that operates in proportion to the steering torque detected by the torque sensor 14 moves the rack shaft 22 in the axial direction via the worm gear 26, the output shaft 12, and the pinion 21. For this reason, the auxiliary steering force generated by the electric motor 25 is transmitted to the rack shaft 22, and the driver's steering force is reduced.

The support structure for the rack shaft 22 will be described.
The support structure includes support means that is held by the housing 6 and supports the rack shaft 22 so as to be movable in the axial direction, and stopper means that restricts movement of the support means with respect to the housing 6.

  The support means includes a rack guide 31 held in the first housing portion 7c, a first end bush 41 as a first support member, and a second support member as a second support member held in the second end housing 8. It comprises an end bush 51 and an intermediate bush 61 as a third support member that is held in the intermediate housing 9 and disposed between the end bushes 41 and 51 in the axial direction. After the bushes 41, 51, 61 are held in the corresponding housings 7, 8, 9, the rack shaft 22 is inserted into the annular bushes 41, 51, 61.

  The columnar rack guide 31 formed in the first housing portion 7c and inserted into the insertion hole 30a of the holding portion 30 protruding from the cylindrical portion 7e is made of a low friction member in surface contact with the back surface 23b of the rack portion 23. A sheet member 31a is provided. The rack guide 31 slides the rack shaft 22 in the axial direction by pressing the rack portion 23 against the pinion 21 by the elastic force of the spring 33 disposed between the cap 32 screwed to the holding portion 30. Support movably.

  Referring to FIG. 1, an annular bush 41 made of synthetic resin is disposed on the opposite side of the bush 61 in the axial direction with the meshing portion of the pinion 21 and the rack portion 23 or the rack guide 31 interposed therebetween. A rack portion 23 is inserted through the rack portion 23. The bush 41 is held between the rack guide 31 and the end opening Ha by a holding portion 40 which is a part of the cylindrical portion 7e, and supports the rack shaft 22 slidably on the back surface 23b.

  The third insertion hole H2 provided in the end portion 7a and having the end opening Ha is a ball joint as a contact portion provided in the rack shaft 22 that defines a rack stroke in one axial direction in the insertion hole H. 24a is an accessible part. The bush 41 inserted in the state of light press-fitting from the end opening Ha into the holding portion 40 abuts on the stepped portion 40c of the holding portion 40, the movement in the insertion direction is restricted, and the bush 41 is press-fitted into the holding portion 40 and fixed. The metal annular ring 49 serving as a stopper is restricted from moving in the anti-insertion direction (that is, the direction opposite to the insertion direction), and is prevented from being removed from the holding portion 40. The ring 49 that is in contact with the stepped portion 40d of the holding portion 40 and is restricted from moving in the insertion direction also serves as a stopper that defines the rack stroke since the ball joint 24a contacts the ring 49. Therefore, as for the bush 41, the step portion 40c and the ring 49 constitute the stopper means.

  An annular bush 51 made of synthetic resin is a part of an end portion 8b as a stopper that contacts a ball joint 24b as a contact portion provided on the rack shaft 22 so as to define a rack stroke in the other direction in the axial direction. Is held by the holding unit 50. The bush 51 supports the rack shaft 22 so as to be slidable on the entire inner peripheral surface thereof. The holding portion 50 is inserted with a diameter larger than that of the insertion hole portion H3 with a portion of the insertion hole H between the end opening Hb and an insertion hole portion H3 provided in the second end housing 8. A hole 50a is provided. The bush 51, which has been reduced in diameter and inserted into the insertion hole 50a from the end opening Hb through the insertion hole portion H3, has a pair of step portions 50b formed by the insertion hole H and the insertion hole 50a in the holding portion 50. Abutting on 50c, the movement in the insertion direction and the anti-insertion direction is restricted. Therefore, for the bush 51, the stopper means is constituted by both step portions 50b and 50c. Note that the bush 51 may be provided with a slit in order to easily reduce the diameter.

  An annular bush 61 made of synthetic resin is provided at a position where the rack portion 23 is not inserted in the range of the rack stroke, and between the holding portions 40 and 50 or between the holding portions 30 and 50. The rack shaft 22 is slidably supported by a curved portion 61c which is held in a part of the holding portion 60 and protrudes radially inward. Therefore, the bush 61 is positioned between the bushes 41 and 51 or between the rack guide 31 and the bush 51 in the axial direction. The stopper means for restricting the movement of the bush 61 in the axial direction includes a step portion 60c constituted by a step portion of a small diameter portion 9c and a large diameter portion 9d, and a thin plate material made of metal, for example, steel. And a ring 62 formed by pressing.

  The bush 61 and the ring 62 are arranged axially from the opening H4a of the insertion hole H4 that is a part of the insertion hole H and provided at the end 9b before the intermediate housing 9 is coupled to the second end housing 8. Are inserted into the insertion hole portion H4. In the holding portion 60, the step portion 60c restricts the movement of the bush 61 in the insertion direction, and the ring 62 is inserted into the holding portion 60 in the same insertion direction as the bush 61 and the bush 61 in the anti-insertion direction. Restrict movement.

A procedure for assembling the power steering apparatus 1 will be described with reference to FIGS.
First, after the worm wheel 26b is integrally coupled to the output shaft 12, the torsion bar 13, the input shaft 11, the second housing portion 7d, and the torque sensor 14 are integrally coupled as described above, so that the input shaft 11, An assembly M in which the bar 13, the output shaft 12, the worm wheel 26b, the torque sensor 14 and the second housing part 7d are integrated is obtained.

  The bearing 16 is arranged so that the assembly M moves toward the assembly position in the first housing part 7c in a state where the rack shaft 22 is inserted into the first housing part 7c and the worm 26a is rotatably supported. Is inserted into the first housing part 7c fixed by press-fitting. Then, the engaging portion 73, the screw portion 12e, the journal portion 12d, and the pinion 21 are sequentially inserted into the bearing 16. In a state where the journal portion 12c of the output shaft 12 to be press-fitted into the bearing 16 is in a position immediately before being press-fitted into the bearing 16, the engaging portion 73 does not protrude from the opening 70 to the outside of the first housing portion 7c. is there.

  Thereafter, in order to press-fit the journal portion 12 c into the bearing 16, a tool 80 engaged with the engaging portion 73 is inserted into the first housing portion 7 c through the opening 70, and the tool 80 engaged with the engaging portion 73 is inserted. Then, by applying a press-fitting load (load for press-fitting) that pulls the assembly M in the assembling direction to the engaging portion 73, the journal portion 12c is press-fitted into the bearing 16, and the output shaft 12, and consequently the assembly M, The first housing portion 7c is press-fitted into the assembly position and assembled (see FIG. 3B). In this state, the pinion 21 meshes with the rack portion 23, and the worm wheel 26b meshes with the worm 26a. Then, the second housing part 7d is fixed to the first housing part 7c by the bolt B1.

  Next, after the tool 80 is removed from the engaging portion 73 and the bearing 17 supporting the journal portion 12d is inserted into the first housing portion 7c and the journal portion 12d through the opening 70, the lock nut 72 is attached to the screw portion 12e. By screwing, after the bearing 17 is prevented from being pulled out in the rotation center line direction A with respect to the output shaft 12, the plug 71 is screwed into the end portion 7c2 of the first housing portion 7c so as to close the opening 70. Thus, the outer ring of the bearing 17 is fixed to the first housing portion 7c.

Next, operations and effects of the embodiment configured as described above will be described.
In the power steering apparatus 1 in which the neutral position of the torque sensor 14 is set corresponding to the predetermined relative position between the input shaft 11 and the output shaft 12 set in the assembly M, the output shaft 12 includes: In order to press-fit the assembly M into the assembly position in the first housing portion 7c, an engaging portion 73 that can be engaged with a tool 80 that moves the assembly M in the press-fitting direction is provided, whereby the first housing portion 7c. Since the press-fitting load is applied to the output shaft 12 through the engaging portion 73 when the assembly M is press-fitted into the assembly M, the relative positions of the input shaft 11, the torsion bar 13, and the output shaft 12 may change due to the press-fitting load. Even when the assembly of the assembly M is completed, the predetermined relative positions of the input shaft 11 and the output shaft 12 set in the state of the assembly M and the neutral position of the torque sensor 14 are maintained. After assembly of M, It is not necessary to adjust the relative positions of the input shaft 11 and the output shaft 12 so that the lux sensor 14 occupies the neutral position. As a result, the assembly of the assembly M to the first housing portion 7c causes the relative positions of the input shaft 11 and the output shaft 12 to deviate from the predetermined relative positions, and thus the rotation between the core 14a and the coils 14b and 14c. Since the deviation of the torque sensor 14 from the neutral position based on the relative position in the center line direction A is prevented and the relative position does not need to be adjusted after the assembly M is assembled, the assembly operation of the power steering device 1 is not necessary. Efficiency is improved.

  The assembly M is press-fitted into a bearing 16 held by the first housing part 7c in the output shaft 12, and the first housing part 7c is provided with an opening 70 on the extension of the output shaft 12 in the assembly direction. The engagement portion 73 is an end portion 12b opposite to the side on which the input shaft 11 is positioned in the rotation center line direction A of the output shaft 12, and is open in a state immediately before the assembly M is press-fitted into the bearing 16. From the first housing portion 7c. Thereby, since the engaging part 73 exists in the edge part 12b on the opposite side to the input shaft 11 in the output shaft 12, it can press-fit without being interrupted by the input shaft 11. Further, the tool 80 is inserted into the first housing part 7c through the opening 70 into the engaging part 73 located in the first housing part 7c at the position of the assembly M just before the start of press-fitting into the first housing part 7c. Thus, since the press-fit load can be applied, it is not necessary to position the engaging portion 73 outside the first housing portion 7c in order to apply the press-fit load to the engaging portion 73. As a result, since the press-fitting work can be performed without being blocked by the input shaft 11, the press-fitting work becomes easy, and it is not necessary to position the engaging portion 73 outside the first housing part 7c before the press-fitting starts. The shaft 12 and thus the power steering device 1 are prevented from being enlarged in the rotation center line direction A.

  At the end 12b of the output shaft 12, a threaded portion into which a journal portion 12d supported by the bearing 17 held by the first housing portion 7c and a lock nut 72 for fixing the bearing 17 in the rotation center line direction A are screwed. 12e is provided, and the engaging portion 73 is positioned closer to the tip of the end portion 12b than the screw portion 12e, so that the tool 80 engages the engaging portion 73 closer to the tip than the screw portion 12e. More specifically, since it engages with the engaging portion 73 with the small-diameter portion 73b being sandwiched, unlike the case where a press-fit load is applied while the screw portion 12e is sandwiched with the tool 80, the thread of the thread portion 12e is The screw part 12e is not damaged by the tool 80 without being crushed by the tool 80.

Hereinafter, an embodiment in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration.
The engaging portion 73 may protrude from the opening 70 to the outside of the first housing portion 7c in a state immediately before the start of press-fitting.
The assembly M has a bearing 16 held on the output shaft 12, and the assembly M is pressed into the first housing portion 7 c so that the assembly M is inserted into the first housing via the bearing 16 on the output shaft 12. It may be press-fitted into the part 7c.

The engaging portion 73 may be configured by a member that is attached to the output shaft 12 and is separate from the output shaft 12. The assembly M may be press-fitted into an assembly position in the first housing portion 7c by being coupled to the output shaft 12 so as not to move relative thereto and applying a press-fitting load to the constituent members constituting the assembly M.
In the above embodiment, the rotational force of the electric motor 25 is transmitted to the rack shaft 22 via the worm gear 26, the output shaft 12 and the pinion 21, but the worm gear 26 is not coupled to the output shaft 12, and therefore the output shaft. 12 may be an electric power steering device of a type that transmits the rotational force of the electric motor to the rack shaft 22 without passing through the pinion 21 and the pinion 21, or an electric power steering device that does not use the worm gear 26 as the transmission mechanism. Good. Furthermore, the power steering apparatus to which the present invention is applied may be a power steering apparatus in which the auxiliary steering force generation mechanism includes an actuator other than the electric motor. In these cases, when the bearing 17 is prevented from being pulled out of the output shaft 12 by the lock nut 72, the rotation of the output shaft 12 is caused by clamping the small diameter portion 73b of the engaging portion 73 with the tool 80. Therefore, when the lock nut 72 for fixing the bearing 17 is screwed to the output shaft 12, the lock nut 72 and the output shaft 12 are prevented from rotating together, so that the assembly work of the bearing 17 is facilitated. Thus, the work efficiency of assembling the power steering device is improved.

1 is a schematic overall view showing a part of a power steering device to which the present invention is applied in cross section. FIG. 2 is a cross-sectional view of a cross section including a rotation center line of an input shaft in the power steering device of FIG. 1. It is a figure explaining the assembly procedure of the power steering apparatus of FIG. 1, (A) shows the state before the assembly is press-fitted into the housing, and (B) is after the assembly is press-fitted into the housing. Indicates the state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Power steering apparatus, 2 ... Handle, 3 ... Gear box, 5 ... Auxiliary steering force generation mechanism, 6-9 housing, 10 ... Input part, 11 ... Input shaft, 12 ... Output shaft, 13 ... Torsion bar, 14 ... Torque sensor, 15-17 ... bearing, 18 ... pin, 19 ... protective cover, 21 ... pinion, 22 ... rack shaft, 23 ... rack part, 25 ... electric motor, 26 ... worm gear, 30 ... holding part, 31 ... rack guide 32 ... Cap, 33 ... Spring, 40 ... Holding part, 41 ... Bushing, 49 ... Ring, 50 ... Holding part, 51 ... Bushing, 60 ... Holding part, 60c ... Step part, 61 ... Bushing, 62 ... Ring, 70 ... Opening, 71 ... Plug, 72 ... Lock nut, 73 ... Engagement part, 80 ... Tool,
B1, B2 ... bolts, G ... storage chamber, D ... dustproof boot, H ... insertion hole, M ... assembly, A ... direction of rotation center line.

Claims (4)

An assembly in which an input shaft to which a steering force from a handle is input and an output shaft coupled to the input shaft via a torsion bar are integrated, and a housing that rotatably supports the assembly on the output shaft And a torque sensor for detecting a steering torque based on a torsion amount of the torsion bar, and the torque corresponding to a predetermined relative position between the input shaft and the output shaft set in the assembly In the power steering device in which the reference position of the sensor is set,
The output shaft is provided with an engaging portion capable of engaging with a tool for moving the assembly in the press-fitting direction in order to press-fit the assembly into an assembly position in the housing. apparatus.   The assembly is press-fitted into the housing via a bearing held in the housing on the output shaft or a bearing held on the output shaft, and the housing has an extension of the output shaft in the assembly direction. An opening is provided, and the engaging portion is an end of the output shaft opposite to the side where the input shaft is located in the direction of the rotation center line, and the assembly is press-fitted into the bearing or the housing. 2. The power steering apparatus according to claim 1, wherein the power steering apparatus is provided at a position that does not protrude from the opening to the outside of the housing in a state immediately before.   The end portion is provided with a journal portion supported by another bearing held by the housing, and a screw portion into which a lock nut for fixing the another bearing in the rotation center line direction is screwed, The power steering apparatus according to claim 2, wherein the engaging portion is positioned closer to a tip of the end portion than the screw portion. Steering force and assembly and output shaft coupled through a torsion bar is integrated with the input shaft and the input shaft is input from the steering wheel, you rotatably supporting said assembly at said output shaft and housings, and a detection to belt Rukusensa the steering torque based on the torsion of the torsion bar, corresponding to a predetermined relative position between the input shaft and the output shaft which is set in the assembly In the method of assembling the power steering apparatus in which the reference position of the torque sensor is set,
A press-fitting load in a direction in which the assembly is press-fitted into an assembly position in the housing is applied to the output shaft or the engaging portion constituting the assembly by a press-fitting tool, which is coupled to the output shaft or the output shaft so as not to be relatively movable. Thus, the assembly method of the power steering apparatus, wherein the assembly is press-fitted into an assembly position in the housing.

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