JP2011079396A - Vehicular steering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive vehicular steering apparatus capable of highly precisely centering a rotating shaft of a motor with a transmission shaft of a transmission apparatus. <P>SOLUTION: The inside of an accommodation chamber R1 partitioned by an intermediate housing 29 and a first transmission housing 27 is partitioned into an external space S1 and an internal space S2, and a cylindrical centering member 50 for centering the rotating shaft 23 with the transmission shaft 32 is provided. A third cylindrical surface 50a of the centering member 50 is fluid-tightly fitted onto a first cylindrical surface 38a formed on a first transmission housing 27 and concentric with the transmission shaft 32. A fourth cylindrical surface 50b of the centering member 50 is fluid-tightly fitted onto a second cylindrical surface 49a formed on the intermediate housing 29 and concentric with the rotating shaft 23. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle steering apparatus.

As an electric power steering apparatus as a vehicle steering apparatus, there is an electric power steering apparatus that includes an electric motor for assisting steering and a transmission device that transmits an output of the electric motor.
In the electric power steering device of Patent Document 1, a control housing in which a control device is accommodated is interposed between a motor housing of an electric motor and a transmission housing in which the transmission device is accommodated. In addition, in order to prevent foreign matter (for example, lubricant and abrasion powder) from the transmission device from entering the control housing, a cylindrical partition that divides the space in the control housing into a central space and a surrounding space. The member is used.

Japanese Patent Application No. 2009-46045

By the way, in patent document 1, in order to ensure the space of said surrounding space widely, the cross section of the fitting part of a control housing and a transmission housing is made into the rectangle. For this reason, there exists a problem that the center of the rotating shaft of an electric motor and the transmission shaft of a transmission device tends to shift | deviate.
On the other hand, in the example of FIGS. 3 and 4 of Patent Document 1, the partition member is screwed to the end face of the control housing. Moreover, in the example of FIG. 5 of patent document 1, the edge part of a partition member is screwed in the screw hole of the end surface of a control housing. However, with such screw coupling, it is difficult to couple the control housing and the transmission housing with such an accuracy that the rotation shaft of the electric motor and the transmission shaft of the transmission can be accurately aligned.

  The present invention has been made based on such a background, and an object thereof is to provide an inexpensive vehicle steering apparatus capable of accurately aligning the rotation shaft of the electric motor and the transmission shaft of the transmission device. To do.

  In order to achieve the above object, the present invention provides a control device (16) for controlling driving of an electric motor (18) having a motor housing (22) and a rotating shaft (23), and a torque via the rotating shaft and a joint. A transmission device (19) having a transmission shaft (32) connected so as to be able to transmit, a transmission housing (26) for housing the transmission device, and an intermediate housing (29) interposed between the motor housing and the transmission housing ), And the inside of the accommodation chamber (R1) defined by the intermediate housing and the transmission housing, the outer space (S1) in which the control device is accommodated, and the inner space (in which the transmission shaft and the rotation shaft are inserted) And the transmission housing and the intermediate housing are cylindrical surfaces (38a, 5) so that the transmission shaft and the rotation shaft are aligned with each other. a; 49a, 50b) if a cylindrical centering member for coupling (50) by Shino fit, to provide a vehicle steering apparatus having a.

  In the present invention, since the cylindrical centering member connects the transmission housing and the intermediate housing by fitting the cylindrical surfaces, the transmission shaft and the rotation shaft can be accurately aligned. The transmission housing includes a first cylindrical surface (38a) concentric with the transmission shaft, and the intermediate housing includes a second cylindrical surface (49a) concentric with the rotating shaft, and the centering member. A third cylindrical surface (50a) that fits liquid-tightly to the first cylindrical surface, a fourth cylindrical surface (50b) that fits liquid-tightly to the second cylindrical surface, (Claim 2). In this case, the outer space and the inner space can be reliably sealed without using an O-ring or other sealing structure, and the structure can be simplified.

  The intermediate housing includes a first cylindrical portion (38) having the first cylindrical surface, and the transmission housing includes a second cylindrical portion (49) having the second cylindrical surface. (Claim 3). In this case, since the centering member is fitted to the first and second cylindrical portions extending from the intermediate housing and the transmission housing, positions of the rotary shaft, the transmission shaft, the joint, and the like disposed in the inner space The length and diameter of the first cylindrical portion and the second cylindrical portion can be freely set according to the shape, and the degree of freedom in design can be increased.

  In the above description, the alphanumeric characters in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

It is a mimetic diagram showing a schematic structure of an electric power steering device as a vehicle steering device of one embodiment of the present invention. It is a partial cross section side view of the steering auxiliary mechanism cut along the axial direction of the rotating shaft of the electric motor. It is sectional drawing to which a part of FIG. 2 was expanded. It is the schematic which looked at the steering assist mechanism from the axial direction of the steering shaft. It is a schematic sectional drawing of the fastening part of the control housing and transmission housing of a steering assist mechanism.

Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of an electric power steering apparatus 1 as a vehicle steering apparatus according to an embodiment of the present invention. Referring to FIG. 1, an electric power steering device 1 includes a steering shaft 3 connected to a steering member 2 such as a steering wheel, an intermediate shaft 5 connected to the steering shaft 3 via a universal joint 4, A pinion shaft 7 connected to the shaft 5 via a universal joint 6 and a rack 8a meshing with the pinion 7a provided in the vicinity of the end of the pinion shaft 7 and extending in the axial direction X1 as the left-right direction of the automobile. It has a rack shaft 8 as a rudder shaft. The pinion shaft 7 and the rack shaft 8 constitute a turning mechanism A1 including a rack and pinion mechanism.

  The rack shaft 8 is supported in a housing 9 fixed to the vehicle body through a plurality of bearings (not shown) so as to be linearly reciprocable along the axial direction X1. Both end portions of the rack shaft 8 protrude to both sides of the housing 9, and tie rods 10 are coupled to the respective end portions. Each tie rod 10 is connected to a corresponding steered wheel 11 via a corresponding knuckle arm (not shown).

When the steering member 2 is operated and the steering shaft 3 is rotated, this rotation is converted into a linear motion in the axial direction X1 of the rack shaft 8 by the pinion 7a and the rack 8a. Thereby, the turning of the steered wheel 11 is achieved.
The steering shaft 3 includes an input shaft 12 connected to the steering member 2 and an output shaft 13 connected to the intermediate shaft 5. The input shaft 12 and the output shaft 13 are connected via a torsion bar 14 so as to be relatively rotatable on the same axis. That is, when a steering torque of a predetermined value or more is input to the steering member 2, the input shaft 12 and the output shaft 13 rotate in the same direction while rotating relative to each other.

A torque sensor 15 arranged around the steering shaft 3 detects the steering torque input to the steering member 2 based on the relative rotational displacement amounts of the input shaft 12 and the output shaft 13. The torque detection result of the torque sensor 15 is input to an ECU 16 (Electronic Control Unit) as a control device.
The electric power steering apparatus 1 includes a steering assist mechanism 17. The steering assist mechanism 17 includes an electric motor 18 for assisting steering, and a speed reduction mechanism 19 as a transmission device for transmitting the output torque of the electric motor 18 to the steering mechanism A1. For example, a three-phase brushless motor is used as the electric motor 18. Further, as the speed reduction mechanism 19, for example, a staggered shaft gear mechanism such as a worm gear, a parallel shaft gear mechanism constituted by a plurality of spur gears or bevel gears, or the like can be used.

  In the present embodiment, a parallel shaft gear mechanism having a small-diameter drive gear 20 and a large-diameter driven gear 21 meshed with the drive gear 20 is used as the speed reduction mechanism 19. The drive gear 20 is rotationally driven by the electric motor 18, and the driven gear 21 is rotationally driven by the drive gear 20. The driven gear 21 is provided so as to be able to rotate together with the output shaft 13 of the steering shaft 3.

  When the electric motor 18 rotationally drives the drive gear 20, the driven gear 21 is rotationally driven by the drive gear 20, and the driven gear 21 and the output shaft 13 rotate together. The rotation of the output shaft 13 is transmitted to the pinion shaft 7 through the intermediate shaft 5. The rotation of the pinion shaft 7 is converted into movement of the rack shaft 8 in the axial direction X1. Thereby, the steered wheel 11 is steered. That is, by rotating the drive gear 20 by the electric motor 18, the steered wheels 11 are steered to assist the driver's steering.

The electric motor 18 is controlled by the ECU 16. The ECU 16 controls the electric motor 18 based on a torque detection result from the torque sensor 15 or a vehicle speed detection result from a vehicle speed sensor (not shown).
FIG. 2 is a schematic partial sectional side view of the steering assist mechanism 17. FIG. 3 is an enlarged view of a part of FIG. FIG. 4 is a schematic view of the steering assist mechanism 17 as viewed along the axial direction of the steering shaft 3.

  As shown in FIG. 2, the electric motor 18 includes a cylindrical motor housing 22, a rotating shaft 23, an annular stator 24 fixed to the inner periphery of the motor housing 22, and the stator 24 facing the rotating shaft 23. And a ring-shaped rotor 25 that rotates together. The stator 24 is fixed to the inner periphery of the motor housing 22 and includes an annular stator core 24a having a plurality of teeth, and a coil 24b wound around each tooth of the stator core 24a. The rotor 25 has an annular rotor core 25a connected to the rotary shaft 23 so as to be able to rotate together with it, and a ring-shaped permanent magnet 25b provided on the outer periphery of the rotor core 25a so as to be able to rotate together. The ring-shaped permanent magnet 25b has a plurality of magnetic poles arranged in the circumferential direction.

The speed reduction mechanism 19 as a transmission device is accommodated in the transmission housing 26. The transmission housing 26 is configured by combining a first transmission housing 27 and a second transmission housing 28 that can be divided in the axial direction Y1 of the steering shaft 3.
A cylindrical intermediate housing 29 is interposed between the motor housing 22 and the first transmission housing 27. The intermediate housing 29 has a first end portion 30 made of an annular protrusion fitted to one end of the motor housing 22 and a second end portion 31 fitted to the first transmission housing 27. .

  The drive gear 20 of the speed reduction mechanism 19 is connected to the outer periphery of the transmission shaft 32 so as to be able to rotate together. The transmission shaft 32 is rotatably supported by the transmission housing 26 via first and second bearings 33 and 34 on both sides of the drive gear 20. The first bearing 33 is held by the first transmission housing 27, and the second bearing 34 is held by the second transmission housing 28. The first bearing 33 is configured by a known seal bearing in which an annular oil seal is interposed between the inner and outer rings, so that the lubricant in the transmission housing 26 does not leak into a partition unit U1 described later. I have to.

  The first transmission housing 27 includes a first outer peripheral wall 35 that surrounds the drive gear 20 and the driven gear 21, an end wall 36 that closes one end of the first outer peripheral wall 35, and the end wall 36 toward the electric motor 18 side. A second outer peripheral wall 37 having a rectangular cross section that extends and a first cylindrical portion 38 that protrudes from the end wall 36 toward the electric motor 18 are provided. One end of the second outer peripheral wall 37 of the first transmission housing 27 is fitted to, for example, the outer periphery of the second end 31 of the intermediate housing 29, whereby the intermediate housing 29 and the first transmission housing 27 are engaged. Thus, a storage chamber R1 for storing the ECU 16 or the like is partitioned.

  An insertion hole 39 for inserting the transmission shaft 32 is formed in the end wall 36. The first bearing 33 supports the transmission shaft 32 rotatably while being held by the bearing holding portion 39 a on the inner periphery of the insertion hole 39. The outer peripheral surface of the first cylindrical portion 38 is formed on a first cylindrical surface 38 a concentric with the bearing holding portion 39 a of the insertion hole 39. Therefore, the first cylindrical surface 38 a of the first cylindrical portion 38 is disposed concentrically with the transmission shaft 32.

On the other hand, the motor housing 22 of the electric motor 18 includes a tubular portion 40 and an end wall 41 that closes one end of the tubular portion 40. A bearing holding portion 42 made of a cylindrical protrusion is formed inside the end wall 41, and the first bearing of the rotating shaft 23 of the electric motor 18 is held by the third bearing 43 held on the inner periphery of the bearing holding portion 42. The end 23a is rotatably supported.
The intermediate housing 29 has an outer peripheral wall 44 having a rectangular cross section, an end wall 45 that closes one end of the outer peripheral wall 44, and an annular protrusion (fitting from the end wall 45 toward the motor housing 22 and fitted to the motor housing 22. Corresponding to the first end 30). The end wall 45 functions as a partition wall that partitions the motor chamber in the motor housing 22 from the storage chamber R1.

An insertion hole 47 through which the rotary shaft 23 of the electric motor 18 is inserted is formed in the end wall 45 as the partition wall. A middle portion of the rotating shaft 23 is rotatably supported by a fourth bearing 48 held by a bearing holding portion 47 a on the inner periphery of the insertion hole 47.
The intermediate housing 29 has a second cylindrical portion 49 extending from the end wall 45 to the speed reduction mechanism 19 side. The outer peripheral surface of the second cylindrical portion 49 is formed on a second cylindrical surface 49 a concentric with the bearing holding portion 47 a of the insertion hole 47. Therefore, the second cylindrical surface 49 a of the second cylindrical portion 49 is disposed concentrically with the rotating shaft 23.

For aligning the rotation shaft 23 of the electric motor 18 and the transmission shaft 32 of the speed reduction mechanism 19 with the first cylindrical portion 38 of the first transmission housing 27 and the second cylindrical portion 49 of the intermediate housing 29. A cylindrical core alignment member 50 is fitted.
As shown in FIG. 3, the centering member 50 has a third cylindrical surface 50a fitted to the first cylindrical surface 38a of the first cylindrical portion 38 at one end, and the other end has a third cylindrical surface 50a. And a fourth cylindrical surface 50b fitted to the second cylindrical surface 49a of the second cylindrical portion 49. The first tubular portion 38, the second tubular portion 49, and the centering member 50 constitute a tubular partition unit U1.

  As described above, the storage chamber R <b> 1 is defined by the intermediate housing 29 and the first transmission housing 27. The partition unit U1 partitions the inside of the storage chamber R1 into an outer space S1 around the partition unit U1 and an inner space S2 inside the partition unit U1. An ECU 16 as a control device is accommodated in the outer space S1. Further, in the inner space S <b> 2, the transmission shaft 32 and the rotating shaft 23 of the electric motor 18 are connected coaxially via a joint 52 so that torque can be transmitted.

The ECU 16 includes a power board 161 on which an FET and other switching elements are mounted, a control board 162 for controlling a power circuit mounted on the power board 161, and a plurality of ripples for removing ripples of current flowing in the electric motor 18. And a relay for cutting off the current flowing through the electric motor 18 as necessary.
A rotational position sensor 71 that detects the rotational position of the rotor 25 of the electric motor 18 is accommodated in the motor housing 22. The rotational position sensor 71 includes a stator 72 fixed to the intermediate housing 29, and a rotor 73 provided so as to be able to rotate together with the rotating shaft 23. A bus bar terminal 74 from each coil 24 b of the stator 24 of the electric motor 18 and a signal line 75 from the rotational position sensor 71 penetrate the end wall 45 and are connected to the power board 161 and the control board 162.

  The centering member 50 includes a large cylinder 53, a small cylinder 54, an annular plate portion 55 that connects the large cylinder 53 and the small cylinder 54, and an annular shape that extends radially inward from the end of the small cylinder 54. The end wall 56 is provided. On the inner periphery of the large cylinder 53, a third cylindrical surface 50a that fits into the first cylindrical surface 38a on the outer periphery of the first cylindrical portion 38 is provided. Further, a fourth cylindrical surface 50 b that fits into the second cylindrical surface 49 a on the outer periphery of the second cylindrical portion 49 is provided on the inner periphery of the end wall 56.

  The joint 52 includes a first member 57 connected to the second end portion 23b of the rotating shaft 23 of the electric motor 18 so as to be able to rotate together with, for example, serration fitting, and an end portion of the transmission shaft 32, for example, press fit. Torque can be transmitted between the first member 57 and the second member 58 by interposing between the second member 58 and the first member 57 and the second member 58 that are coupled to each other so as to be able to rotate together. And an elastic member 59 connected to the.

  As shown in FIG. 4, the outer peripheral wall 44 of the intermediate housing 29 has a rectangular shape, and a pair of mounting flanges 60 are extended from positions facing each other on the outer peripheral wall 44. On the other hand, as shown in FIG. 5, a pair of mounting flanges 61 facing the pair of mounting flanges 60 of the intermediate housing 29 are extended from the second outer peripheral wall 37 of the first transmission housing 27. A screw insertion hole 60 a is inserted into the mounting flange 60, and a screw hole 61 a is formed in the mounting flange 61. The fixing screw 62 is inserted into the screw hole 61a of the corresponding mounting flange 61 of the first transmission housing 27 through the mounting flanges 60 and 61 through the screw insertion holes 60a of the mounting flanges 60 of the intermediate housing 29. The intermediate housing 29 and the first transmission housing 26 are fastened to each other.

According to the present embodiment, the cylindrical centering member 50 connects the first transmission housing 27 and the intermediate housing 29 by fitting the corresponding cylindrical surfaces 38a, 50a; 49a, 50b. The transmission shaft 32 of the mechanism 19 and the rotation shaft 23 of the electric motor 18 can be accurately aligned.
Further, the third cylindrical surface 50a of the centering member 50 is liquid-tightly fitted to the first cylindrical surface 38a concentric with the transmission shaft 32 formed in the first transmission housing 27, and the intermediate Since the fourth cylindrical surface 50b of the centering member 50 is fluid-tightly fitted to the second cylindrical surface 49a formed on the housing 29 and concentric with the rotating shaft 23, an O-ring or other sealing structure is adopted. Even if not, the space between the outer space S1 and the inner space S2 can be reliably sealed, and thus the structure can be simplified.

  Since the centering member 50 is fitted to the first cylindrical portion 38 extending from the first transmission housing 27 and the second cylindrical portion 49 extending from the intermediate housing 29, it is disposed in the inner space S2. The length and diameter of the first cylindrical portion 38 and the second cylindrical portion 49 can be freely set according to the position and shape of the rotary shaft 23, the transmission shaft 32, the joint 52, etc., and the degree of design freedom is high. can do.

  At the time of assembly, the intermediate housing 29 and the transmission housing 26 are assembled together with the centering member 50 mounted in advance on the second cylindrical portion 49 of the intermediate housing 29. The second end portion 23b of the supported rotating shaft 23 and the transmission shaft 32 supported by the transmission housing 26 and the first member 57 of the joint 52 can be serrated.

The present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, the centering member 50 is formed of a two-stage cylinder. Alternatively, it may be a cylinder having three or more stages.
Further, either one of the first cylindrical portion 38 and the second cylindrical portion 49 is abolished, and a core is formed on the inner peripheral cylindrical surface of the insertion hole formed in the first transmission housing 27 or the intermediate housing 29. You may make it fit the corresponding cylindrical surface of a matching member.

  Further, the core alignment member 50 may be integrally formed with either one of the first cylindrical portion 38 and the second cylindrical portion 49 with a single material. In addition, the present invention can be variously modified within the scope of the claims.

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering device (vehicle steering device), 2 ... Steering member, 3 ... Steering shaft, A ... Steering mechanism, 16 ... ECU (control device), 17 ... Steering assist mechanism, 18 ... Transmission motor, 19 ... Deceleration mechanism (transmission device), 20 ... drive gear, 21 ... driven gear, 22 ... motor housing, 23 ... rotating shaft, 26 ... transmission housing, 27 ... first transmission housing, 28 ... second transmission housing, 29 ... Intermediate housing 32 ... transmission shaft 38 ... first cylindrical portion 38a ... first cylindrical surface 49 ... second cylindrical portion 49a ... second cylindrical surface 50 ... centering member 50a ... 3rd cylindrical surface, 50b ... 4th cylindrical surface, U1 ... Centering unit, R1 ... Storage chamber, S1 ... Outer space, S2 ... Inner space

Claims (3)

A control device for controlling the driving of an electric motor having a motor housing and a rotating shaft;
A transmission device having a transmission shaft coupled to the rotary shaft via a joint so as to transmit torque;
A transmission housing that houses the transmission device;
An intermediate housing interposed between the motor housing and the transmission housing;
The inside of the accommodation chamber defined by the intermediate housing and the transmission housing is partitioned into an outer space in which the control device is accommodated and an inner space in which the transmission shaft and the rotation shaft are inserted, and the transmission shaft and the above A vehicle steering apparatus comprising: a cylindrical centering member that connects the transmission housing and the intermediate housing by fitting between cylindrical surfaces so as to center the rotation shaft. In claim 1,
The transmission housing includes a first cylindrical surface concentric with the transmission shaft,
The intermediate housing includes a second cylindrical surface concentric with the rotation shaft,
The centering member includes a third cylindrical surface that is liquid-tightly fitted to the first cylindrical surface, and a fourth cylindrical surface that is liquid-tightly fitted to the second cylindrical surface. Vehicle steering system. In Claim 2, the intermediate housing includes a first cylindrical portion having the first cylindrical surface,
The transmission housing includes a second cylindrical portion having the second cylindrical surface.

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