ELECTRIC POWER STEERING UNIT, RACK AND PINION TYPE WITH BELT TENSIONER

Abstract

Rack and pinion type electric power steering device comprising: a rack housing (320; 420; 520) surrounding a rack (109) coupled to a driven pulley (290), having a through hole (380) through which a motor shaft (221) of a motor (130) coupled to a driving pulley (280) passes, and having a guide hole (326; 426; 526) spaced from the through hole (380) and having a first inclined portion (324; 424; 524) on any one of the upper surface and the lower surface thereof, the cross section of which changes in a direction in which the motor (130) is coupled; a motor housing (330; 430; 530) to which the rack housing (320; 420; 520) is coupled, to which the motor (130) is mounted such that the motor shaft (221) passes through the through hole (380), and which has a coupling recess (332; 432; 532) at a location corresponding to the guide hole (326; 426; 526), ​​and a support body (312; 412; 512) passing through the guide hole (326; 426; 526) to be coupled to the coupling recess (332; 432; 532), and a second inclined portion (314; 414; 514) on any one of the upper surface and the lower surface thereof corresponding to the first inclined portion (324; 424; 524) such that the support body (312; 412; 512) corresponds to the guide hole (326; 426; 526) and the driving pulley (280) is moved away from the driven pulley (290) when they are coupled.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The present invention relates to a rack-type electric power steering apparatus. More particularly, it relates to a rack-type electric power steering apparatus in which the tensile force of a belt increases as the distance between a motor shaft and a rack increases, since a second inclined portion of a support body passing through a guide hole is moved upward along a first inclined portion to be inserted into a coupling groove, and thus noise and damage to the belt can be prevented. Furthermore, when the support body is inserted into a coupling groove through a third inclined portion of a coupling groove and a motor housing is moved upward, the tensile force of the belt increases as the distance between the motor shaft and the tension rod increases, and thus noise and damage to the belt can be prevented. 2. Description of the state of the art

[0002] Generally, a steering device refers to a device that allows the driver to turn a steering wheel to freely change the direction of travel of a vehicle, and it is a device that arbitrarily changes the center of rotation around which the front wheels are turned to help the driver drive the vehicle in a desired direction.

[0003] Fig. 1 is a partial sectional view of a prior art rack and pinion type electric power steering apparatus.

[0004] As in Fig. 1, the rack-type electric steering apparatus according to the related art includes a rack 109 extending in a transverse direction of a vehicle and having a rack gear part on one side of its outer peripheral surface, a pinion shaft 104 having a pinion gear part engaged with the rack gear part, a ball screw part 150 having balls 201, a ball screw 203, and a ball nut 205 engaged with the ball screw 203 via the balls 201, a belt-type transmission unit 140 connecting the ball nut 205 and a motor shaft 221, a motor 130, and a motor housing 240 fixed to a rack housing 223 by bolt coupling and surrounding the motor 130.

[0005] The pinion shaft 104 is connected to a steering wheel via a steering shaft, and the rack 109, which has a spindle of predetermined length on one side of its outer surface, is installed inside the rack housing 223.

[0006] The ball screw part 150 includes a ball nut 205 formed coaxially with the rack 109 and surrounding the rack 109, and the balls 201 that make contact with the ball screw 203 formed on the outer surface of the rack 109.

[0007] The ball nut 205 is rotated together with the motor shaft 221 when the motor shaft 221 rotates, and a bearing 207 is arranged between an outer peripheral surface of the ball nut 205 and an inner peripheral surface of the rack housing 223 for smooth rotation of the ball nut 205.

[0008] The belt-type transmission unit 104 includes a belt 230 connecting the motor shaft 221 and the ball nut 205, and transmits an assist force generated by the motor 130 through the ball nut 205 to the rack 109 in proportion to a steering torque applied to the steering wheel.

[0009] That is, when the motor shaft 221 is rotated, the ball nut 205, which receives a rotational force of the motor shaft 221 via the belt 230, is also rotated, and when the ball nut 205 rotates, the rack 109 is moved axially linearly according to the movements of the balls 201 and the ball screw 203.

[0010] Fig. 2 is a side view of a motor housing and a rack housing of the rack-and-pinion type electric power steering apparatus according to the related art.

[0011] The motor 130 is fixed by coupling the motor housing 240 surrounding the motor 130 to the rack housing 223 by means of bolts 270.

[0012] When the motor shaft 221 drives the belt 230 while being rotated to rotate the ball nut 205 during a steering operation, a force that attracts the motor shaft 221 and a shaft of the rack 109 including the ball nut 205 toward each other is exerted by a tensile force of the belt 230.

[0013] Since the generated force is concentrated on a coupling area of ​​the bolts of the motor housing 240 and the rack housing 223, which is mechanically most sensitive, and the motor shaft 221 is moved toward the rack 109 including the ball nut 205 by a phenomenon in which the bolts 300 are relieved due to vibration and a shock that occurs while the motor shaft 221 is rotated during a steering operation, the tensile force of the belt 230 decreases, noise occurs between the belt 230 and a drive pulley 280 or a driven pulley 290, and the belt 230 is damaged.

[0014] From JP 2013-159 161 A, a rack-type electric power steering device is known, which comprises: a rack housing surrounding a rack coupled to a driven pulley, having a through hole through which a motor shaft of a motor coupled to a driving pulley passes, and having a guide hole spaced from the through hole and having a first inclined portion; a motor housing to which the rack housing is coupled, to which the motor is mounted such that the motor shaft passes through the through hole, and having a coupling groove at a location corresponding to the guide hole; and a support body passing through the guide hole to be coupled to the coupling groove such that the driving pulley is moved away from the driven pulley when they are coupled.Further power steering devices with belt tensioning devices are known from JP 2013-224 114 A, US 2014 / 0 302 954 A1, DE 103 04 189 A1 and JP 2014- 108 670 A. SUMMARY OF THE INVENTION

[0015] The present invention was made in an effort to solve the aforementioned problems and provides a rack-type electric power steering apparatus in which the tensile force of a belt increases as the distance between a motor shaft and a rack increases. This is because a second inclined portion of a support body passing through a guide hole is moved upward along a first inclined portion to be inserted into a coupling groove, and thus noise and damage to the belt can be prevented. Also, when the support body is inserted into a coupling groove through a third inclined portion of a coupling groove and a motor housing is moved upward, the tensile force of the belt increases as the distance between the motor shaft and the rack increases, and thus noise and damage to the belt can be prevented.

[0016] To achieve the object, there is provided a rack-type electric power steering apparatus according to claim 1, which specifically includes: a rack housing surrounding a rack coupled to a driven pulley, having a through hole through which a motor shaft of a motor coupled to a driven pulley passes, a guide hole spaced from the through hole, and a first inclined portion whose cross section changes in a direction in which the motor is coupled; a motor housing to which the rack housing is coupled, to which the motor is fixed such that the motor shaft passes through the through hole and has a coupling recess at a location corresponding to the guide hole;and a support body passing through the guide hole to be coupled with the coupling recess and having a second inclined portion corresponding to the first inclined portion such that the driving pulley is moved away from the driven pulley when they are coupled.;

[0017] As described above, according to the present invention, since the second inclined portion of the support body passing through the guide hole is moved upward along the first inclined portion to be inserted, the tensile force of the belt becomes larger as the distance between the motor shaft and the rack becomes larger, and accordingly, noise and damage of the belt can be prevented.

[0018] Furthermore, when the support body is inserted through the third inclined portion of the coupling groove and the motor housing is moved upward, the tensile force of the belt becomes larger as the distance between the motor shaft and the rack increases, and accordingly, noise and damage of the belt can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings in which: Fig. 1 is a partial sectional view of a rack and pinion type electric power steering apparatus according to the related art; Fig. 2 is a side view of a motor housing and a rack housing of a rack-and-pinion type electric power steering apparatus according to the related art; Fig. 3 is a side view of a motor housing and a rack housing of a rack-type electric power steering apparatus according to a first embodiment of the present invention; Fig. 4 is a front view of the motor housing and the rack housing of the rack-type electric power steering apparatus according to the first embodiment of the present invention; Fig. 5 is a perspective view illustrating a support body of the rack-and-pinion type electric power steering apparatus according to the first embodiment of the present invention; Fig. 6 is a partial sectional view illustrating a process of coupling the support body to the rack housing and the motor housing in the rack-type electric power steering apparatus according to the first embodiment of the present invention; Fig. 7 is a partial sectional view illustrating a state in which the support body is coupled to the rack housing and the motor housing according to the first embodiment of the present invention; Fig. 8 is a partial sectional view illustrating a process of coupling a support body to a rack housing and a motor housing in a rack-type electric power steering apparatus according to a second embodiment of the present invention; and Fig. 9 is a partial sectional view illustrating a state in which a support body is coupled to a rack housing and a motor housing in a rack-type electric power steering apparatus according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the elements of the present invention, terms "first," "second," "A," "B," "(a)," "(b)," and the like may be used. These terms are used merely to distinguish one structural element from other structural elements, and a property, order, sequence, and the like of a corresponding structural element are not limited by the term. It should be noted that when the description states that one component is "connected," "coupled," or "joined" to another component, a third component may be "connected," "coupled," and "joined" between the first and second components, although the first component may be directly connected, coupled, or joined to the second component.

[0021] Unless otherwise stated in the detailed description of the present invention, the upper side of Fig. 4 described as an upper side, the lower side of Fig. 4 is described as a lower side, the left side of Fig. 4 is described as one side, and the right side of Fig. 4 is described as a facing page to make the description easy.

[0022] Fig. 3 is a side view of a motor housing and a rack housing of the rack-type electric power steering apparatus according to a first embodiment of the present invention.

[0023] Fig. 4 is a front view of the motor housing and the rack housing of the rack type electric power steering apparatus according to the first embodiment of the present invention.

[0024] Fig. 5 is a perspective view illustrating a support body of the rack and pinion type electric power steering apparatus according to the first embodiment of the present invention.

[0025] Fig. 6 is a partial sectional view illustrating a process of coupling the support body to the rack housing and the motor housing in the rack-type electric power steering apparatus according to the first embodiment of the present invention.

[0026] Fig. 7 is a partial sectional view illustrating a state in which the support body is coupled to the rack housing and the motor housing according to the first embodiment of the present invention.

[0027] According to the Fig. 3 to 7, in a detailed description of a feature structure of the first embodiment of the present invention, the rack-type electric power steering apparatus according to the first embodiment of the present invention includes: a rack housing 320 surrounding a rack 109 coupled to a driven pulley 290, having a through-hole 380 through which a motor shaft 221 of a motor 130 coupled to a driving pulley 280 passes in an axial direction of the rack 109, and a guide hole 326 spaced from the through-hole 380, extending in the axial direction of the rack 109, and having a first inclined portion 324 whose cross section changes such that a vertical width thereof becomes narrower in a direction in which a motor 130 is coupled; a motor housing 330 to which the rack housing 320 is coupled;to which the motor 130 is mounted such that the motor shaft 221 passes through the through hole 380 and has a coupling recess 332 at a location corresponding to the guide hole 326, and a support body 312 passing through the guide hole 326 to be coupled to the coupling recess 332 and having a second inclined portion 314 corresponding to the first inclined portion 324 such that the driving pulley 280 is moved away from the driven pulley 290 when they are coupled.

[0028] A belt-type transmission unit 300 includes a driving pulley 280 coupled to the motor shaft 221, a driven pulley 290 coupled to a ball nut 205, and a belt 230 connecting the driving pulley 280 and the driven pulley 290, and an assist force generated by the motor 130 in proportion to a steering torque applied to a steering wheel is transmitted to the rack 109 through the ball nut 205.

[0029] That is, the ball nut 205, which receives a rotational force of the motor shaft 221, is also rotated by the belt 230 when the motor shaft 221 is rotated, and the rack 109 is axially linearly moved by balls and a ball screw when the ball nut 205 is rotated.

[0030] The rack housing 320 surrounds the rack 109 to which the driven pulley 290 is coupled, has a through hole 380 through which the motor shaft 221 of the motor 130 to which the driving pulley 280 is coupled passes in the axial direction of the rack 109, and has a guide hole 326 spaced from the through hole 380, extending in the axial direction of the rack 109, and having a first inclined portion 324 whose cross section changes so that a vertical width thereof becomes narrower in a direction in which a motor 130 is coupled.

[0031] Here, the through hole 380 may be a slot such that a portion of the motor housing 330 is inserted into the slot and the motor shaft 221 is moved up and down.

[0032] The guide hole 326 has a first flat portion 322 extending from the first inclined portion 324 and having a constant vertical width in a direction in which the motor 130 is coupled.

[0033] That is, the guide hole 326 has a first flat portion 322 having a constant vertical width on a side where the motor 130 is coupled, and a first inclined portion 324 whose vertical width becomes larger as it goes from the first flat portion 322 to an opposite side.

[0034] The guide hole 326 has the first inclined portion 324 on any one of the upper surface and the lower surface thereof, and a support body 312 having a second inclined portion 314 corresponding to the first inclined portion 324 on any one of the upper surface and the lower surface thereof, such that the support body 312 is coupled to the guide hole 326 to correspond thereto.

[0035] In the first embodiment of the present invention, since the first inclined portion 324 is formed on the lower surface of the guide hole 326 and the second inclined portion 314 is formed on the lower surface of the support body 312 so that the second inclined portion 314 of the support body 312 passing through the guide hole 326 is moved upward along the first inclined portion 324 of the guide hole 326 to be inserted into the coupling recess 332, the motor housing 330 is moved upward so that the distance between the motor shaft 221 and the rack 109 becomes larger, thereby increasing the tensile force of the belt 230, and accordingly, noise and damage to the belt 230 are prevented.

[0036] The motor 130 is coupled to the motor housing 330 surrounding the motor 130 by bolts.

[0037] The motor housing 330 is coupled to the rack housing 320 such that the motor 130 is attached to the motor housing 330 and the motor shaft 221 passes through the through hole 380, and the coupling recess 332 is formed at a location corresponding to the guide hole 326.

[0038] One or more slots 390 are formed in the rack housing 320 such that the driving pulley 280 coupled to the motor shaft 221 is moved away from the driven pulley 290 coupled to the rack 109, and one or more screw holes are formed in the motor housing 330 so that the tensile force of the belt 230 is adjusted by preliminarily coupling the bolts 270 to the screw holes after the bolts 270 are passed through the slots 390 and moving the motor housing 330 up and down, and the motor housing 330 is fixed to the rack housing 320 by fastening the bolts 270 in the state where the tensile force of the belt 230 is adjusted.

[0039] The coupling recess 332 has a third inclined portion 334 on its upper surface such that a vertical width thereof becomes narrower as it goes to a side on which the motor 130 is coupled.

[0040] Accordingly, when the support body 312 is inserted into the coupling groove 332 through the third inclined portion 334 of the coupling groove 332 and the motor housing 330 is simultaneously moved upward, the distance between the motor shaft 221 and the rack 109 becomes larger, thereby increasing the tensile force of the belt 230 and thus preventing noise and damage to the belt 230.

[0041] When the support body 312 passes through the guide hole 326 and is coupled with the coupling recess 332, the second inclined portion 314 is formed corresponding to the first inclined portion 324 so that the driving pulley 280 is moved away from the driven pulley 290.

[0042] That is, the support body 312 has the second inclined portion 314 corresponding to the first inclined portion 324 of the guide hole 326 on any one of the upper surface and the lower surface thereof.

[0043] In addition, the support body 312 has a knob 310 projecting from one end in a direction in which a vertical width thereof becomes larger in an axial direction of the rack 109.

[0044] In the rack type electric power steering apparatus according to the first embodiment of the present invention, when the motor housing 330 is preliminarily coupled to the rack housing 320 as shown in Fig. 6A and then the support body 312 is inserted into the guide hole 326 of the rack housing 320, as shown in Fig. 6B, the support body 312 having the second inclined portion 314 guides the motor housing 330 upward along the first inclined portion 324 of the rack housing 320 to be inserted into the guide hole 326.

[0045] As in Fig. 6C, when the support body 312 is inserted and the motor housing 330 is simultaneously moved upward through the third inclined portion 334 of the motor housing 330, the tensile force of the belt 230 is increased in proportion to the distance h by which the motor housing 330 is moved along the inclined portion.

[0046] Accordingly, since the second inclined portion 314 of the support body 312 passing through the guide hole 326 is moved upward along the first inclined portion 324 of the guide hole 326 and inserted into the coupling recess 332, the motor housing 330 is moved upward and the distance between the motor shaft 221 and the rack 109 becomes larger, thereby increasing the tensile force of the belt 230 and thus preventing noise and damage to the belt 230.

[0047] When the support body 312 is inserted into the coupling groove 332 through the third inclined portion 334 of the coupling groove 332 and the motor housing 330 is simultaneously moved upward, the tensile force of the belt 230 increases as the distance between the motor shaft 221 and the rack 109 increases, and accordingly, noise and damage to the belt 230 can be prevented.

[0048] Here, as in Fig. 7, the inserted support body 312 may be fixed to the rack housing 320 by a fastening method such as gluing 340, welding or caulking.

[0049] Fig. 8 is a partial sectional view illustrating a process of coupling a support body to a rack housing and a motor housing in a rack-type electric power steering apparatus according to a second embodiment of the present invention.

[0050] The second embodiment of the present invention is the same as the first embodiment of the present invention except for a guide hole 426 and a support body 412, and therefore only the structures and operations of the guide hole 426 and the support body 412 will be described.

[0051] As illustrated, in the rack-type electric power steering apparatus according to the second embodiment of the present invention, two or more first inclined portions 424 and two or more first flat portions 422 formed in the guide hole 426 are sequentially repeatedly formed inward, and the support body 412 is configured such that second inclined portions 414 and second flat portions 416 are sequentially repeatedly formed to correspond to the first inclined portions 424 and the first flat portions 422.

[0052] That is, in the guide hole 426, a first flat portion 422a having a constant vertical width is formed on one side in a direction in which the motor 130 is coupled, a first inclined portion 424a is formed such that a vertical width thereof becomes larger as it goes from the first flat portion 422a to an opposite side, and in sequence, a first flat portion 422b is formed from the first inclined portion 424a to an opposite side, and a first inclined portion 424b is formed from the first flat portion 422b to an opposite side such that a vertical width thereof becomes larger.

[0053] In the guide hole 426, according to the embodiment of the present invention, three second inclined portions 314 and three first flat portions 422 are sequentially repeatedly formed, and also in the support body 412, three second inclined portions 414 and three second flat portions 416 are sequentially repeatedly formed corresponding to the guide hole 426.

[0054] That is, in the support body 412, a second flat portion 416a having a constant vertical width is formed on one side in a direction in which the motor 130 is coupled, a second inclined portion 414a is formed such that a vertical width thereof becomes larger as it goes from the second flat portion 416a to an opposite side, and in turn, a second flat portion 416b is formed from the second inclined portion 414a to an opposite side, and a second inclined portion 414b is formed such that a vertical width thereof becomes larger from the second flat portion 416b to an opposite side.

[0055] In the guide hole 426 and the support body 412 formed in this way, since the inclined portions 414 and 424 and the flat portions 416 and 422 are repeatedly formed, the tensile force of the belt 230 can be adjusted in steps.

[0056] In the rack-type electric power steering apparatus according to the second embodiment of the present invention, when the motor housing 430 is preliminarily coupled to the rack housing 420 as shown in Fig. 8A, and then the support body 412 is inserted into the guide hole 426 of the rack housing 420, as shown in Fig. 8B, the support body 412 having the second inclined portions 414 guides the motor housing 430 upward along the first inclined portions 424 of the rack housing 420 to be inserted.

[0057] As in Fig. 8C, the support body 412 is inserted and the motor housing 430 is moved upward through the third inclined portion 434 of the motor housing 430, and the tensile force of the belt 230 is increased by the distance h by which the motor housing 430 is moved along the inclined portion.

[0058] Here, when the pulling force is high, a knob 410 of the support body 412 is pulled to fix the support body 412 to the rack housing 420 such that the upper second inclined portion 414a is located at the lower first inclined portion 424b and the upper second flat portion 416a is located at the lower first flat portion 422b.

[0059] Fig. 9 is a partial sectional view illustrating a state in which a support body is coupled to a rack housing and a motor housing in a rack-type electric power steering apparatus according to a third embodiment of the present invention.

[0060] The third embodiment of the present invention is the same as the first embodiment of the present invention except for a guide hole 526 and a support body 512, and thus only the structures and operations of the guide hole 526 and the support body 512 will be described.

[0061] As in Fig. 9, the rack-type electric power steering apparatus according to the third embodiment of the present invention further includes a fixing member 528 coupled to or formed at one end in a direction in which a vertical width of the guide hole 526 becomes larger, and a plug screw 550 coupled to the fixing member 528 while supporting the support body 512.

[0062] That is, the fixing member 528 having an internal thread portion 560a is coupled to or formed at one end of the guide hole 526 in a direction in which a vertical end thereof becomes larger, and the locking screw 550 having an external thread portion 560b is coupled to the internal thread portion 560a of the fixing member 528 to support the support body 512.

[0063] Alternatively, an external thread portion may be formed in the fixing part 528, and an internal thread portion may be formed in the locking screw 550, so that the locking screw 550 may be coupled to the fixing part 528 and the locking screw 550 may be connected to the fixing part 528 by press fitting.

[0064] Thereafter, a fixing recess 510 is formed in a surface of the support body 512 facing the locking screw 550, and a fixing bead 552 inserted into the fixing recess 510 is formed in the locking screw 550.

[0065] Accordingly, since the fixing bead 552 of the locking screw 550 is fitted into the fixing recess 510 of the support body 512, the support body 512 is supported by the rack housing 520 without being moved, thereby supporting the motor housing 530 more firmly.

[0066] Furthermore, since a coupling tool recess 554 is formed in a surface opposite to the surface on which the fixing bead 552 of the locking screw 550 is formed, and a coupling tool is inserted into the coupling tool recess 554 to fix the locking screw 550, the locking screw 550 is firmly fixed to the fixing part 528.

[0067] As described above, according to the present invention, since the second inclined portion of the support body passing through the guide hole is moved upward along the first inclined portion to be inserted into the coupling groove, the tensile force of the belt becomes larger as the distance between the motor shaft and the rack increases, and accordingly, noise and damage of the belt can be prevented.

[0068] Furthermore, when the support body is inserted into the coupling groove through the third inclined portion of the coupling groove and the motor housing is moved upward, the tensile force of the belt becomes larger as the distance between the motor shaft and the rack increases, and accordingly, noise and damage of the belt can be prevented.

Claims

[1] Rack and pinion type electric power steering device comprising: a rack housing (320; 420; 520) surrounding a rack (109) coupled to a driven pulley (290), having a through hole (380) through which a motor shaft (221) of a motor (130) coupled to a driving pulley (280) passes, and having a guide hole (326; 426; 526) spaced from the through hole (380) and having a first inclined portion (324; 424; 524) on any one of the upper surface and the lower surface thereof, the cross section of which changes in a direction in which the motor (130) is coupled; a motor housing (330; 430; 530) to which the rack housing (320; 420; 520) is coupled, to which the motor (130) is mounted such that the motor shaft (221) passes through the through hole (380), and which has a coupling recess (332; 432; 532) at a location corresponding to the guide hole (326; 426; 526), ​​and a support body (312; 412; 512) passing through the guide hole (326; 426; 526) to be coupled to the coupling recess (332; 432; 532), and a second inclined portion (314; 414; 514) on any one of the upper surface and the lower surface thereof corresponding to the first inclined portion (324; 424; 524) such that the support body (312; 412; 512) corresponds to the guide hole (326; 426; 526) and the driving pulley (280) is moved away from the driven pulley (290) when they are coupled. [2] A rack and pinion type electric power steering apparatus according to claim 1, wherein said through hole (380) is a slit extending upward and downward in such a manner that said motor shaft (221) is moved upward and downward. [3] The rack-and-pinion type electric power steering apparatus according to claim 1 or 2, wherein the guide hole (326; 426; 526) is configured to form a first flat portion (322; 422) having a constant vertical width from the first inclined portion (324; 424; 524) to a side on which the motor (130) is coupled. [4] The rack-type electric power steering apparatus according to any one of claims 1 to 3, wherein two or more first inclined portions (424) and two or more first flat portions (422) formed in the guide hole (426) are sequentially repeatedly formed inwardly, and the support body (412) is configured such that second inclined portions (414) and second flat portions (416) are sequentially repeatedly formed to correspond to the first inclined portions (424) and the first flat portions (422). [5] A rack-type electric power steering apparatus according to any one of claims 1 to 4, wherein said coupling recess (332; 432; 532) has a third inclined portion (334; 434; 534) on the upper surface thereof such that a vertical width thereof becomes narrower as it goes toward a side on which said motor (130) is coupled. [6] A rack and pinion type electric power steering apparatus according to any one of claims 1 to 5, further comprising: a fixing part (528) coupled to or formed at one end in a direction in which a vertical width of the guide hole (526) becomes larger; and a locking screw (550) coupled to the fixing part (528) while supporting the support body (512). [7] A rack-type electric power steering apparatus according to claim 6, wherein screw parts (560a; 560b) are formed on an inner peripheral surface of the fixing part (528) and an outer peripheral surface of the plug screw (550) such that the plug screw (550) is screw-coupled to the fixing part (528). [8] The rack-type electric power steering apparatus according to any one of claims 6 to 7, wherein the support body (512) is configured such that a fixing recess (512) is formed in a surface thereof facing the plug screw (550), and a fixing bead (552) fitted into the fixing recess (512) is formed on the plug screw (550). [9] A rack-type electric power steering apparatus according to any one of claims 1 to 8, wherein the support body (312; 412) is configured such that a knob (310; 410) protrudes from one end in a direction in which a vertical width thereof becomes larger in an axial direction of the rack shaft (109).

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