JP2012111418A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering device capable of preventing a lowering in belt tension.SOLUTION: A belt tension adjustment mechanism of the EPS has a circular adjustment pin insertion hole 51a in a second motor attachment part 51 of an end housing 13. Further, the belt tension adjustment mechanism has an adjustment pin 55 inserted to the adjustment pin insertion hole 51a. A cylindrical shaft part 56 which is rotatably inserted and supported by an adjustment pin insertion hole 51a is formed on the adjustment pin 55 and a through-hole 58 to which a second bolt 53 is inserted is formed on a position off-centered from the center C2 of the shaft part 56.

Description

  The present invention relates to an electric power steering apparatus that applies power of a motor to a rack shaft as an assist force for assisting a steering operation.

  As this kind of electric power steering device (EPS), for example, Patent Document 1 is cited. In the electric power steering apparatus of Patent Document 1, an electric motor is fixed to a gear housing in which a rack shaft is accommodated via a collar (end housing). The power generated by the driving of the electric motor is transmitted to the rack shaft via the belt type transmission mechanism. As shown in the schematic diagram of FIG. 5, the belt-type transmission mechanism includes an input pulley 91 that is rotationally driven by an electric motor 90, an output pulley 92 that is connected to the rack shaft via a ball screw mechanism, an input pulley 91, and A belt 93 wound around an output pulley 92.

  Further, the electric power steering apparatus includes a belt 93 tension adjusting section (belt tension adjusting mechanism). The tension adjusting portion is configured by bolt insertion holes 95 a and 95 b formed in the pair of coupling portions 95 of the collar 94. One of the two bolt insertion holes 95a and 95b (left side in FIG. 5) is formed in a circular hole shape, and the other (right side in FIG. 5) bolt insertion hole 95b extends in the vertical direction. It is formed in a hole shape. Adjustment bolts B inserted into the respective bolt insertion holes 95a and 95b (in FIG. 5, only the adjustment bolt B inserted into the other bolt insertion hole 95b is shown) are screwed into the gear housing.

  The tension of the belt 93 is adjusted by causing the collar 94 to swing with respect to the gear housing with the circular bolt insertion hole 95a as a swing fulcrum. At this time, the collar 94 is swung within an adjustment region T that is allowed by the length of the long hole-like bolt insertion hole 95b. When the distance D between the rotation center line 91a of the input pulley 91 and the rotation center line 92a of the output pulley 92 is adjusted by the swing of the collar 94 and the tension of the belt 93 is adjusted appropriately, each adjustment is performed. The tension adjustment of the belt 93 is completed by screwing the bolt B into the gear housing.

JP 2005-343434 A

  By the way, the input pulley 91 is always pulled toward the output pulley 92 by the tension of the belt 93. In the electric power steering device of Patent Document 1, the length direction of the long hole-like bolt insertion hole 95b extends in the direction in which the input pulley 91 is pulled toward the output pulley 92 side. For this reason, there is a problem that the tension of the belt 93 causes the electric motor 90 to be drawn toward the output pulley 92 side along the elongated hole insertion hole 95b, and the belt 93 is loosened and the tension is lowered.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an electric power steering apparatus capable of preventing a decrease in belt tension.

  In order to solve the above-described problems, the invention according to claim 1 is directed to a housing that accommodates a rack shaft, and a fixing member that penetrates the housing is fixed to the motor so that the motor is fixed. In the electric power steering apparatus that transmits the power generated by the driving of the motor to the rack shaft through a belt from the output shaft of the motor, and applies the power to the rack shaft as an assisting force for assisting a steering operation. As the belt tension adjustment mechanism, the housing has a circular adjustment pin insertion hole in the housing and an adjustment pin inserted into the adjustment pin insertion hole. The adjustment pin is inserted into the adjustment pin insertion hole. A shaft portion that is rotatably inserted and supported is formed, and the fixing member is fixed to the motor at a position eccentric from the center of the shaft portion. The fixing member is summarized in that the through hole is inserted is formed to.

  According to the above invention, when the adjustment pin is rotated in the adjustment pin insertion hole, the fixing member revolves around the center of the shaft portion, and the motor to which the fixing member is fixed moves along with the revolution. For this reason, the output shaft of the motor moves relative to the rack shaft, and the distance between the two shafts changes, so that the belt tension is adjusted. When the belt tension is adjusted, the belt tension causes a pulling force to the rack shaft side to act on the motor output shaft, and the pulling force to the rack shaft side also to the fixing member that fixes the motor to the housing. Is working. At this time, the fixing member is inserted and supported by the adjustment pin, and the adjustment pin is inserted and supported by the circular adjustment pin insertion hole. The end face of the adjustment pin located on the side attracted by the drawing force is the adjustment pin. It contacts the inner surface of the insertion hole and is always supported. For this reason, even if a pulling force is applied to the fixing member, the fixing member is prevented from moving toward the rack shaft, and a decrease in belt tension is prevented.

  The invention according to claim 2 is the electric power steering device according to claim 1, wherein a head having a diameter larger than that of the shaft portion is formed at one axial end of the shaft portion. To do.

According to the said invention, an adjustment pin can be easily rotated by operating a head.
According to a third aspect of the present invention, in the electric power steering apparatus according to the second aspect, a latching portion is formed on one of the head and the housing, and the fixing member is on the other. The gist of the invention is that a hooked portion for hooking the hooking portion is formed along with the fixing to the motor.

According to the above invention, the adjustment pin can be prevented from rotating by the latching of the latching portion with respect to the latched portion, and the fixing member can be prevented from moving due to the rotation of the adjustment pin.
According to a fourth aspect of the present invention, in the electric power steering apparatus according to any one of the first to third aspects, the housing is inserted with a fixing member different from the fixing member. The gist is that a hole is formed and the insertion hole is formed in a long hole shape.

  According to the above invention, when adjusting the belt tension, when the adjustment pin is rotated and the motor is moved, the other fixing member moves in the length direction of the insertion hole. Therefore, the motor is allowed to move by the length of the insertion hole, and the belt tension can be adjusted.

  According to a fifth aspect of the present invention, in the electric power steering apparatus according to the fourth aspect, the housing is formed with an output shaft receiving hole through which the output shaft is inserted, and the rack through which the rack shaft is inserted. A shaft housing hole is formed, and a straight line connecting the center shafts of the output shaft housing hole and the rack shaft housing hole is defined as a center line, the center line of the insertion hole intersects the center line. The gist is that it is formed.

  According to the above invention, even if a pulling force to the rack shaft side based on the belt tension acts on the output shaft, the inner surface of the insertion hole comes into contact with another fixing member to suppress the movement of the motor, This can contribute to prevention of belt tension drop.

  According to the present invention, it is possible to prevent a decrease in belt tension.

The schematic block diagram of an electric power steering apparatus. (A) is a disassembled perspective view which shows the tension adjustment mechanism of a belt, (b) is a perspective view which shows an adjustment pin. (A)-(c) is a front view of the state which adjusted the belt tension by rotating the adjustment pin. FIG. 4B is a cross-sectional view taken along line 4-4 of FIG. The schematic diagram which shows background art.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, in an electric power steering apparatus (EPS) 10, a housing 12 into which a rack shaft 11 is inserted includes a substantially cylindrical first housing 14 in which almost the entire rack shaft 11 is accommodated, and a rack shaft. 11 is formed by joining a substantially cylindrical second housing 15 in which a part of 11 is accommodated. An end housing 13 for fixing the electric motor 40 as a motor to the housing 12 is formed on the outer peripheral surface of the first housing 14 on the second housing 15 side.

  In the housing 12, tie rods 17 are connected to both ends of the rack shaft 11 via rack ends 16. A known ball joint is used for the rack end 16 of the present embodiment. The tip of the tie rod 17 is connected to a knuckle (not shown) that supports the steered wheel 18.

  In the housing 12, a pinion shaft 20 constituting the proximal end side of the steering shaft 19 is rotatably supported in a state of intersecting with the rack shaft 11. The steering shaft 19 according to the present embodiment includes a pinion shaft 20, a column shaft 22 provided with a steering 21 at one end, and an intermediate shaft 23 that connects the pinion shaft 20 and the column shaft 22. The rack teeth 11 a formed on the peripheral surface of the rack shaft 11 are meshed with the pinion shaft 20.

  That is, the rack shaft 11 is connected to the steering shaft 19 via a well-known rack and pinion mechanism 24, and the rotation of the steering shaft 19 due to the operation of the steering 21 is performed by the rack and pinion mechanism 24. Converted to reciprocating motion. And the rudder angle of the steered wheel 18 is changed by the movement of the rack shaft 11 in the axial direction.

  The EPS 10 of the present embodiment is a so-called rack assist type EPS that applies assist force to the steering system by converting the rotation (power) of the electric motor 40 into reciprocation of the rack shaft 11 using the ball screw device 30. It is configured. More specifically, as a rack parallel type EPS in which the electric motor 40 is disposed with respect to the housing 12 so that the output shaft 40a of the electric motor 40 and the rack shaft 11 are substantially parallel to each other in the rotation center lines P1 and P2. It is configured.

  The rack shaft 11 is configured as a screw shaft by forming a screw portion 11b having a screw groove formed on the outer periphery thereof. The ball screw device 30 is formed by screwing a ball screw nut 33 to the screw portion 11b via a plurality of balls 32.

  The ball screw nut 33 is configured to be rotatable integrally with the driven pulley 34, and a drive pulley 36 that is drivingly connected via a belt 35 is arranged in parallel on the radially outer side of the driven pulley 34. . A drive pulley 36 is connected to the output shaft 40 a of the electric motor 40, and a belt 35 is stretched between the drive pulley 36 and the driven pulley 34. The rotational power of the output shaft 40a in the electric motor 40 is transmitted to the ball screw nut 33 through the drive pulley 36, the belt 35, and the driven pulley 34, and the relative rotation of the ball screw nut 33 with respect to the rack shaft 11 is reduced to the rack shaft. 11 reciprocating motions. Therefore, the EPS 10 of the present embodiment assists the steering operation with the axial pressing force (driving force) based on the motor torque via the belt-type transmission mechanism including the driven pulley 34, the belt 35, and the driving pulley 36. Therefore, it is configured to apply to the steering system as an assist force (auxiliary steering force).

Next, the tension adjusting mechanism of the belt 35 in the EPS 10 of the present embodiment will be described.
First, the belt tension adjusting mechanism on the electric motor 40 side will be described. As shown in FIG. 2A, in the electric motor 40, an end plate 42 is joined to the projecting side end surface of the output shaft 40 a from the motor housing 41. A cylindrical support portion 42a that rotatably supports the output shaft 40a is projected on one end face of the end plate 42, and a pair of flange portions 43 that form a plate shape are supported on the end plate 42. It extends outward from 42a. Each flange portion 43 is formed with a screw hole 43a.

Next, the tension adjusting mechanism of the belt 35 on the first housing 14 side will be described.
As shown in FIGS. 2A and 3A, the first housing 14 is formed with a rack shaft housing hole 14a for housing the rack shaft 11, and the end housing 13 has an electric motor 40. The output shaft accommodating hole 13a for accommodating the output shaft 40a is formed. In the first housing 14, a plate-shaped first motor mounting portion 50 (left side in FIGS. 2A and 3A) and a second motor mounting portion 51 are formed on the outer peripheral surface of the end housing 13. (The right side in FIG. 2A and FIG. 3A) is formed so as to extend in directions opposite to each other across the output shaft accommodation hole 13a. The first motor mounting portion 50 is formed with a bolt insertion hole 50a as an insertion hole having a long hole shape.

  Here, in the first housing 14, a virtual line (straight line) connecting the central axis L1 of the output shaft accommodating hole 13a and the central axis L2 of the rack shaft accommodating hole 14a is defined as a central line C of the first housing 14. In this case, the center line N extending in the length direction of the bolt insertion hole 50a intersects the center line C obliquely. A first bolt 52 as another fixing member for fixing the electric motor 40 is inserted into the bolt insertion hole 50a, and the first motor mounting portion 50 (housing 12) is inserted through the bolt insertion hole 50a. The first bolt 52 penetrating through is screwed into the screw hole 43 a of the electric motor 40.

  The second motor mounting portion 51 is formed with a circular adjustment pin insertion hole 51a. Further, in the second motor mounting portion 51, a latching recess 51b as a hooked portion is formed in an annular shape around the adjustment pin insertion hole 51a so as to surround the adjustment pin insertion hole 51a.

  As shown in FIG. 2B, the adjustment pin 55 inserted into the adjustment pin insertion hole 51 a includes a cylindrical shaft portion 56 and a positive portion extending outwardly from one outer peripheral surface of the shaft portion 56. The head portion 57 is formed with a larger diameter than the shaft portion 56. No screw is formed on the outer peripheral surface of the shaft portion 56, and the outer diameter of the shaft portion 56 is set to be slightly smaller than the hole diameter of the adjustment pin insertion hole 51a. For this reason, the shaft portion 56 is rotatably supported in the adjustment pin insertion hole 51a in a state where movement in the radial direction is restricted.

  The adjustment pin 55 is formed with a through hole 58 penetrating from the head portion 57 to the entire shaft portion 56. The through hole 58 is formed at a position where the center C <b> 1 is shifted outward from the center C <b> 2 of the shaft portion 56, and the through hole 58 is formed at a position eccentric with respect to the shaft portion 56. Further, a pair of conical hooking portions 57 a are provided on the rear surface of the head 57 so as to protrude from a position sandwiching the shaft portion 56. The latching portion 57a is formed so as to be latchable in the latching recess 51b of the second motor mounting portion 51 in a state where the adjustment pin 55 is inserted into the adjustment pin insertion hole 51a.

  As shown in FIG. 4, the second bolt 53 as a fixing member is inserted into the through hole 58 of the adjustment pin 55, and the second motor mounting portion 51 (housing 12) is connected to the adjustment pin 55 through the adjustment pin insertion hole 51a. The penetrated second bolt 53 is screwed into the screw hole 43 a of the electric motor 40. The adjustment pin 55 is rotatable relative to the second bolt 53 screwed into the screw hole 43a. In the present embodiment, the adjustment pin insertion hole 51 a of the second motor mounting portion 51, the adjustment pin 55, and the second bolt 53 constitute a tension adjustment mechanism for the belt 35.

  Next, a structure for fixing the electric motor 40 to the end housing 13 will be described. The first bolt 52 is inserted into the bolt insertion hole 50 a of the first motor attachment portion 50, and penetrates the first motor attachment portion 50 and is screwed into the screw hole 43 a of the electric motor 40. The adjustment pin 55 is inserted into the adjustment pin insertion hole 51 a of the second motor mounting portion 51, and the second bolt 53 that has passed through the through hole 58 of the adjustment pin 55 is inserted into the screw hole 43 a of the electric motor 40. It is screwed. Further, in a state where the second bolt 53 is screwed into the screw hole 43 a, the latching portion 57 a of the head 57 is latched on the latching recess 51 b of the second motor mounting portion 51, and the adjustment pin 55 is rotated. It is regulated. The electric motor 40 is fixed to the end housing 13 by screwing the first and second bolts 52 and 53 into the screw holes 43a.

Next, tension adjustment of the belt 35 will be described.
First, the second bolt 53 is slightly screwed out of the screw hole 43a, and the adjustment pin 55 is retracted from the adjustment pin insertion hole 51a until the latching portion 57a is detached from the latching recess 51b. The adjustment pin 55 is rotatably supported in the adjustment pin insertion hole 51a while being retracted from the adjustment pin insertion hole 51a. When the head 57 of the adjustment pin 55 is gripped with a tool (hexagon wrench or the like) and the adjustment pin 55 is rotated in the adjustment pin insertion hole 51a, the second bolt 53 is attached to the shaft portion 56 (adjustment pin 55). Revolving around the center C2 with the center C2 as the center of rotation. Then, the electric motor 40 to which the second bolt 53 is screwed moves as the second bolt 53 revolves. At this time, as the electric motor 40 moves, the other first bolt 52 screwed to the electric motor 40 also moves. However, the movement of the first bolt 52 is permitted by the elongated hole insertion hole 50a. . As the first bolt 52 moves in the bolt insertion hole 50a, the electric motor 40 swings with the first bolt 52 as a fulcrum.

  As shown in FIG. 3A, when the adjustment pin 55 is rotated so that the second bolt 53 is positioned below the adjustment pin insertion hole 51a (closer to the rack shaft 11), the electric motor 40 causes the rack shaft 11 to rotate. Move to get closer. Then, in the output shaft accommodation hole 13a, the output shaft 40a and the drive pulley 36 both move so as to approach the rack shaft 11 and the driven pulley 34. As a result, the distance between the rotation center line P1 of the output shaft 40a (drive pulley 36) and the rotation center line P2 of the rack shaft 11 (driven pulley 34) is adjusted to D1.

  As shown in FIG. 3B, when the adjustment pin 55 is rotated and the second bolt 53 is positioned to the left (close to the output shaft 40a) in the adjustment pin insertion hole 51a, the electric motor 40 is slightly moved from the rack shaft 11. Move away. Then, in the output shaft accommodation hole 13a, both the output shaft 40a and the drive pulley 36 move so as to be slightly separated from the rack shaft 11 and the driven pulley 34. As a result, the distance between the rotation center line P1 of the output shaft 40a (drive pulley 36) and the rotation center line P2 of the rack shaft 11 (driven pulley 34) is adjusted to D2. This distance D2 is slightly longer than the distance D1.

  As shown in FIG. 3C, when the adjustment pin 55 is rotated and the second bolt 53 is positioned above the adjustment pin insertion hole 51a (a position away from the rack shaft 11), the electric motor 40 is moved to the rack. Move away from the axis 11. Then, the output shaft 40a and the drive pulley 36 both move away from the rack shaft 11 and the driven pulley 34 in the output shaft accommodation hole 13a. As a result, the distance between the rotation center line P1 of the output shaft 40a (drive pulley 36) and the rotation center line P2 of the rack shaft 11 (driven pulley 34) is adjusted to D3. This distance D3 is slightly longer than the distances D1 and D2.

  Then, the electric motor 40 is moved to adjust the distance between the output shaft 40a and the drive pulley 36, the rack shaft 11 and the driven pulley 34, and when the tension of the belt 35 is adjusted to an appropriate tension, the adjustment pin 55 The shaft portion 56 is inserted into the adjustment pin insertion hole 51a, and the latching portion 57a is latched to the latching recess 51b. Thereafter, the first bolt 52 and the second bolt 53 are further tightened into the screw hole 43a of the flange portion 43 while preventing the position of the second bolt 53 from fluctuating, and the first housing 52 and the second bolt 52, 53 are attached to the end housing 13. The electric motor 40 is fixed.

Next, the operation of the tension adjusting mechanism of the belt 35 will be described.
As shown in FIGS. 3A to 3C, when the tension of the belt 35 is adjusted and the electric motor 40 is fixed to the end housing 13, the driving pulley 36 (the electric motor 40 is driven by the tension of the belt 35. ) Has a pulling force acting on the driven pulley 34 side. Therefore, the pulling force toward the driven pulley 34 based on the tension of the belt 35 also acts on the second bolt 53 that fixes the electric motor 40 to the end housing 13 via the electric motor 40. At this time, the second bolt 53 is inserted and supported by the adjustment pin 55, and the adjustment pin 55 is inserted into the adjustment pin insertion hole 51a in a state where the cylindrical shaft portion 56 is inserted into the circular adjustment pin insertion hole 51a. It is supported. That is, the adjustment pin 55 that supports the second bolt 53 has the inner surface of the adjustment pin insertion hole 51a positioned on the outer peripheral side of the shaft portion 56, and the peripheral surface of the adjustment pin 55 positioned on the side attracted by the pulling force. The (end face) is always supported in contact with the inner surface of the adjustment pin insertion hole 51a. For this reason, even if a pulling force acts on the second bolt 53, the adjustment pin 55 that supports the second bolt 53 is prevented from moving to the driven pulley 34 side. Moving to the driven pulley 34 side is prevented. As a result, the drive pulley 36 is not pulled toward the driven pulley 34, and the belt 35 is prevented from loosening due to the pulling.

According to the above embodiment, the following effects can be obtained.
(1) In the tension adjustment mechanism of the belt 35, the shaft portion 56 of the adjustment pin 55 is inserted and supported in the circular adjustment pin insertion hole 51a, and the second bolt 53 that revolves as the adjustment pin 55 rotates is adjusted. The pin 55 is inserted at a position eccentric from the center C2. For this reason, even if a pulling force toward the driven pulley 34 based on the tension of the belt 35 acts on the second bolt 53 fixed to the electric motor 40, the second bolt 53 moves toward the driven pulley 34. As a result, the tension of the belt 35 can be prevented from decreasing as a result of the drive pulley 36 not being pulled toward the driven pulley 34.

  (2) The second bolt 53 is inserted at a position eccentric from the center C2 of the shaft portion 56, and the adjustment pin 55 is rotatably inserted into the circular adjustment pin insertion hole 51a. The tension of the belt 35 is adjusted by rotating the adjustment pin 55 in the adjustment pin insertion hole 51a and causing the second bolt 53 to revolve. Therefore, unlike the background art, the tension adjusting mechanism of the present embodiment is different from the case where the belt tension is adjusted using a long hole extending in the direction in which the pulling force acts due to the belt tension. The oblong holes used for this purpose have been abolished. Therefore, in this embodiment, even if the pulling force toward the driven pulley 34 acts on the second bolt 53, the electric motor 40 does not move along the long hole as in the background art, and the belt No decrease in the tension of 35 occurs.

  (3) In the adjustment pin 55, the cylindrical shaft portion 56 is integrally formed with a head portion 57 having a larger diameter than the shaft portion 56. By gripping the head 57 with a tool and operating the tool, the adjustment pin 55 can be easily rotated, and the tension of the belt 35 can be easily adjusted.

  (4) A latching portion 57a is formed on the head 57 of the adjustment pin 55, and the latching portion 57a is latched on the second motor mounting portion 51 when the second bolt 53 is tightened to the screw hole 43a. The recess 51b is hooked. By this latching, the adjustment pin 55 can be prevented from rotating due to vibrations of the electric motor 40, and the second bolt 53 is prevented from moving along with the rotation of the adjustment pin 55, and the tension of the belt 35 is reduced. Can be prevented.

  (5) In the tension adjusting mechanism of the belt 35, the first bolt 52 is used in addition to the second bolt 53 in order to fix the electric motor 40 to the end housing 13. The first bolt 52 is inserted into an elongated bolt insertion hole 50 a formed in the first motor mounting portion 50 of the end housing 13. When adjusting the tension of the belt 35, the electric motor 40 is allowed to move by the length of the bolt insertion hole 50a. Here, the center line N of the bolt insertion hole 50 a obliquely intersects the center line C of the first housing 14. For this reason, even if a pulling force toward the driven pulley 34 based on the tension of the belt 35 acts on the drive pulley 36, the inner surface of the bolt insertion hole 50 a contacts the first bolt 52 and the electric motor 40 moves. This can contribute to prevention of a decrease in the tension of the belt 35.

  (6) The tension adjustment mechanism of the belt 35 includes an adjustment pin insertion hole 51 a formed in the second motor attachment portion 51, a bolt-shaped adjustment pin 55, and a second bolt 53. The belt 35 can be prevented from loosening with a simple and inexpensive configuration in which the adjustment pin insertion hole 51a is formed in a predetermined shape and the through hole 58 is formed at a predetermined position of the adjustment pin 55.

  (7) The shaft portion 56 of the adjustment pin 55 is formed in a cylindrical shape, and the through hole 58 is formed at a position eccentric from the center C2 of the shaft portion 56. Then, the adjustment pin 55 is rotated with the center C2 as the rotation center, and the tension of the belt 35 is adjusted by the position change of the second bolt 53 accompanying the rotation. Since the position of the second bolt 53 is an arbitrary position on the rotation locus of the second bolt 53, fine tension adjustment is possible.

In addition, you may change the said embodiment as follows.
In the embodiment, the bolt insertion hole 50a is formed in a long hole shape. However, when adjusting the tension of the belt 35, if the movement of the electric motor 40 with the rotation of the adjustment pin 55 is allowed, the bolt insertion hole 50a The shape is not limited to a long hole shape.

In the embodiment, only two hooks 57a are formed on the head 57, but the number of hooks 57a may be arbitrarily changed.
In the embodiment, the latching recess 51b for latching the latching portion 57a is formed in the second motor mounting portion 51. However, the latching recess 51b may not be provided, and in this case, the following change is made. Also good. By fitting the latching portion 57a around the adjustment pin insertion hole 51a in the second motor attachment portion 51 (housing 12), the second motor attachment portion 51 is plastically deformed, and the plastically deformed second motor attachment portion. The latching portion 57a may be latched with 51 as the latched portion. In this case, the latching portion 57a (adjustment pin 55) is formed of a material having high hardness (iron or the like), and the second motor mounting portion 51 (housing 12) serving as the latched portion is harder than the latching portion 57a. It is preferable to form with a low material (aluminum etc.). In addition, when the latching portion is fitted into the latched portion, the latching portion and the material of the latched portion may be appropriately changed so that the latched portion is elastically deformed.

O The latching part 57a of the 2nd volt | bolt 53 and the latching recessed part 51b of the 2nd motor attachment part 51 are not necessary.
In the embodiment, the latching portion 57a is projected from the adjustment pin 55, and the latching recess 51b is recessed from the second motor mounting portion 51. However, the latching portion is projected from the second motor mounting portion 51, A hooking recess as a hooked portion may be provided in the head 57 of the adjustment pin 55. Alternatively, a latching portion may be provided on the second motor mounting portion 51, and the head 57 of the adjustment pin 55 may be a latched portion, and the latching portion may be fitted into the head 57 to be latched.

  In the embodiment, the adjustment pin 55 is rotated by operating the head 57 of the adjustment pin 55 with a tool. However, the head 57 may be omitted, and is projected from the shaft portion 56 instead of the head 57. The adjusting pin 55 may be rotated by operating the operating unit.

In the embodiment, the electric motor 40 is embodied as a motor, but a motor driven by an external drive source such as an engine may be used.
In the embodiment, the second bolt 53 is embodied as a fixing member. However, the fixing member is press-fitted into a fixing hole formed in the electric motor 40 as long as the electric motor 40 can be fixed to the end housing 13. It may be a pin, or may be a fixing member having another fixing type.

  In the embodiment, the second bolt 53 is used as the fixing member. However, after the tension of the belt 35 is adjusted using the second bolt 53 and tightened, another bolt is used in addition to the first bolt 52. The electric motor 40 may be fixed to the end housing 13.

  In the embodiment, the belt 35 is stretched over the drive pulley 36 connected to the output shaft 40a and the driven pulley 34 connected to the rack shaft 11 to enable power transmission. However, the power transmission mechanism is not limited to this. , May be changed as appropriate. For example, the sprocket connected to the output shaft 40a and the sprocket connected to the rack shaft 11 may be connected by a chain so that power can be transmitted.

  In the embodiment, the adjustment pin insertion hole 51a is formed in a circular shape. However, the adjustment pin insertion hole 51a can rotate the shaft portion 56 of the adjustment pin 55 on the inner side, and draw toward the driven pulley 34 side. Even if a force is applied, as long as the peripheral surface of the adjustment pin 55 on the drawing side abuts and the movement of the adjustment pin 55 can be restricted, an ellipse or polygonal shape that is almost circular may be used.

  In the embodiment, the shaft portion 56 of the adjustment pin 55 is formed in a cylindrical shape. However, if the shaft portion 56 is rotatable in the adjustment pin insertion hole 51a, the shaft portion 56 has a substantially cylindrical or polygonal tube shape. Also good.

  C ... center line, C2 ... shaft center, L1, L2 ... center axis, N ... center line, 10 ... EPS (electric power steering device), 11 ... rack shaft, 12 ... housing, 13a ... output shaft receiving hole, 14a ... Rack shaft accommodation hole, 35 ... Belt, 40 ... Electric motor as motor, 40a ... Output shaft, 50a ... Bolt insertion hole as insertion hole, 51a ... Adjustment pin insertion hole, 51b ... Hook as hooked portion Stop recess 52... First bolt as another fixing member 53. Second bolt as a fixing member 55. Adjustment pin 56. Shaft portion 57. Head portion 57 a. .

Claims (5)

In the housing that houses the rack shaft, the motor is fixed by fixing a fixing member penetrating the housing to the motor, and the power generated by driving the motor is transmitted from the motor output shaft through the belt. In the electric power steering device that transmits the power to the rack shaft and applies the power to the rack shaft as an assist force for assisting a steering operation.
As the tension adjustment mechanism of the belt,
While having a circular adjustment pin insertion hole in the housing,
It has an adjustment pin inserted through the adjustment pin insertion hole,
A shaft portion that is rotatably inserted and supported in the adjustment pin insertion hole is formed in the adjustment pin, and the fixing member is fixed to the motor at a position eccentric from the center of the shaft portion. An electric power steering apparatus, wherein a through-hole through which a member is inserted is formed.   The electric power steering apparatus according to claim 1, wherein a head portion having a larger diameter than the shaft portion is formed at one axial end of the shaft portion.   A latching portion is formed on one of the head and the housing, and a latched portion on which the latching portion is latched when the fixing member is fixed to the motor is formed on the other. The electric power steering apparatus according to claim 2. The housing is formed with an insertion hole through which a fixing member different from the fixing member is inserted, and the insertion hole is formed in a long hole shape. The electric power steering device according to the item. The housing is formed with an output shaft receiving hole through which the output shaft is inserted, and a rack shaft receiving hole through which the rack shaft is inserted, and the output shaft receiving hole and the central axis of the rack shaft receiving hole are The electric power steering apparatus according to claim 4, wherein the insertion hole is formed such that a center line of the insertion hole intersects the center line, where a straight line connecting the two is a center line.

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