JP2590689Y2 - Electric power steering device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus, and more particularly to an electric power steering apparatus having a backlash adjusting mechanism such as a bevel gear or a hypoid gear mechanism.

[0002]

2. Description of the Related Art In a vehicle or the like, an electric motor that detects a steering torque generated in a steering system by a torque sensor, drives an electric motor connected to the steering system in accordance with the detected value, and outputs an auxiliary torque to the steering system. 2. Description of the Related Art A power steering apparatus is known.

[0003] Some electric power steering devices are arranged such that the rotation axis of the electric motor is orthogonal to the output shaft of the steering system due to restrictions on the mounting space and the like. In such an electric steering apparatus, the rotating shaft of the electric motor and the output shaft of the steering system are connected by, for example, a bevel gear or a hypoid gear mechanism, and power is transmitted while reducing the speed.

[0004]

One problem with the electric power steering apparatus described above is that it is necessary to appropriately set the backlash that occurs between the gears that mesh with the bevel gear or the hypoid gear mechanism.
If the backlash is too small, the meshing gears will compete with each other, and if the backlash is too large, the meshing tooth surfaces will collide due to sudden torque fluctuations, which may cause hammering noise and tooth damage. And smooth torque transmission becomes difficult.

Therefore, in the prior art, in such a gear mechanism, one of a bevel gear or a hypoid gear mechanism is mounted on a shaft member and supported by a bearing so as to be relatively movable with respect to the other gear. A configuration in which the backlash is adjusted by interposing a spacer between the shaft member and the bearing has been considered. However, in such a configuration, it is necessary to measure and measure the backlash before assembling before assembling, or measure the backlash once after assembling, replace the spacer again, and perform adjustment by trial and error. , The work was troublesome.

On the other hand, Japanese Patent Application Laid-Open No. 4-5168 discloses that one gear of a bevel gear or a hypoid gear mechanism is mounted on a shaft member, supported by a bearing so as to be relatively movable with respect to the other gear, and is adjusted by an adjusting plug. A configuration is described in which the backlash is adjusted by adjusting the axial position of the bearing.

In this configuration, the backlash can be adjusted by using an adjusting plug from the outside after the assembly, but the axial direction of the shaft member is suppressed by one bearing. Therefore, when excessive torque is transmitted, the shaft member may move largely in the axial direction within the range of the play existing in the bearing, and the backlash may increase depending on the magnitude of the auxiliary steering force. Was caused. Further, if a small backlash is set from the beginning of the assembly in consideration of an increase in the backlash of the bevel gear or the hypoid gear mechanism, a problem of the backlash being too small during a normal operation is caused.

An object of the present invention is to make it possible to easily adjust the backlash of the bevel gear mechanism and to apply a preload to the bearing, so that the axial movement of the shaft member can be restricted, so that it is compact and inexpensive. An object of the present invention is to provide an electric power steering device having a simple backlash mechanism.

[0009]

To achieve the above object, an electric power steering apparatus according to the present invention comprises a housing, a steering torque detecting means for detecting a steering torque generated in a steering system, and a steering torque detecting means. An electric motor having a rotating shaft that generates a rotating force according to the detection result of the means,
A transmission mechanism for transmitting the torque of the electric motor to the steering system, the transmission mechanism being connected to a small gear connected to a rotation shaft of the electric motor, and an output shaft of the steering system,
In addition, in an electric power steering apparatus including a bevel gear mechanism that meshes with a large gear having an axis that is not parallel to the axis of the pinion, the rotary shaft connected to the pinion cannot rotate in the axial direction but rotates. The gear is supported by the housing so as to be freely movable, and the large gear is coupled to move in the rotational direction and the axial direction integrally with the output shaft of the steering system, and the output shaft is connected to the housing. Are supported by first and second bearings so as to be rotatable with respect to each other. Each of the bearings includes an outer ring, an inner ring, and a rolling element sandwiched between the two wheels. The outer ring of the bearing is supported so as to be movable in the axial direction with respect to the housing, and the inner ring of the first bearing is restricted from moving with respect to the output shaft at least in a direction away from the second bearing. To be taken The inner ring of the second bearing is supported so as to be movable in the axial direction with respect to the output shaft, and further includes an outer ring of the first bearing with respect to the housing. A first moving member for driving the inner ring of the second bearing relative to the output shaft, and a second moving member for driving the inner ring of the second bearing relative to the output shaft in the axial direction. By driving the first moving member, the output shaft is moved in the axial direction through the outer ring, the rolling element, and the inner ring of the first bearing, whereby the tooth surfaces of the pinion and the large gear are moved. After the outer ring of the second bearing abuts on the first moving member by the driving of the second moving member, the outer rings of the first and second bearings are connected to each other. In a state where movement in the approaching direction is prevented,
Further, since the inner rings of the first and second bearings are moved in a direction in which the inner rings approach each other, play generated in the first and second bearings is eliminated.

[0010]

According to the electric power steering apparatus of the present invention, the output shaft is moved in the axial direction via the outer ring, the rolling element and the inner ring of the first bearing by driving the first moving member. Accordingly, the tooth surface of the small gear and the tooth surface of the large gear are brought close to each other, and the outer ring of the second bearing is brought into contact with the first moving member by driving the second moving member. After the contact, the inner rings of the first and second bearings are further moved in a direction in which the inner rings of the first and second bearings are in a state where the outer rings of the first and second bearings are prevented from moving in the direction of being closer to each other. Thereby, the play generated in the first and second bearings is eliminated. Thus, by performing a simple operation with a simple configuration, the backlash of the bevel gear mechanism and the play of the bearing can be eliminated.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a main part of an electric power steering apparatus according to a first embodiment of the present invention. In FIG. 1, an input shaft 2 and an output shaft 3 extend inside a housing 1 including a main body 1a and a lid member 1b. The hollow input shaft 2 has an upper end connected to a steering shaft (not shown) and is rotatably supported by the housing 1 by a bearing 4. Note that the inner ring of the bearing 4 is loosely fitted to the outer periphery of the input shaft 2 for a reason described later. A torsion bar 5 having one end connected to the input shaft 2 and the other end connected to the output shaft 3 extends inside the input shaft 2.

A detection device is provided around the lower end of the input shaft 2 for detecting the steering torque based on the torsion bar 5 being twisted in proportion to the torque received.
This detection device comprises a slider 6 fitted externally so as to be rotatable relative to the input shaft 2 and movable in the axial direction, an inner end inserted into a groove formed at an upper end of the output shaft 3 and an outer end And a helical groove 2a formed in the outer periphery of the lower end side of the input shaft 3 and a concave portion 6 of the slider 6.
a steel ball 8 that is movable in the space defined by
, A spring 12 for urging the slider 6 upward, and a potentiometer 10 connected to the outer periphery of the slider 6 for measuring the amount of movement of the slider 6. This detecting device is, for example, disclosed in Japanese Utility Model Laid-Open No.
As disclosed in Japanese Patent Application Laid-Open No. H10-264, the configuration is not described in detail below.

A pinion gear 3a is formed at the center of the output shaft 3, and a rack shaft 11 extending in the direction perpendicular to the plane of the drawing.
With the rack teeth 11a. The rack shaft 11 is connected to wheels via a steering mechanism (not shown). The rack shaft 11 includes a rack guide 12a, a spring 12b,
Known rack support device 1 including lock member 12c
2, and is pressed toward the pinion gear 3a.

A large bevel gear 13 as a large gear is fixedly mounted on the outer periphery of the upper end of the output shaft 3 by shrink fitting or the like. An upper bearing 14 is fitted near the large bevel gear 13 at the upper end of the output shaft 3. The upper bearing 14, which is the first bearing, includes an outer ring 14a, an inner ring 14b, and a ball 14c sandwiched between the two rings. The outer ring 14a is loosely fitted to the housing 1 for a reason described later. On the other hand, the inner ring 14b is in contact with a step 3b formed at the upper end of the output shaft 3a, and
4 is configured not to move upward with respect to the output shaft 3.

A lower bearing 15 as a second bearing is fitted to a lower end of the output shaft 3. The lower bearing 15 is
5a, inner ring 15b, and ball 15c sandwiched between both wheels
The outer ring 15a is provided with a substantially annular adjusting screw 16
And is supported by the housing 1. The adjusting screw 16 has a structure in which the depth is reduced, and the output shaft 3
When the inner ring 15b of the lower bearing 15 is moved upward by tightening the lock nut 17 screwed into the male screw portion 3c formed at the lower end of the outer ring 15a, the outer ring 15a and the adjusting screw 16 come into contact with each other. I have. The male screw 3c and the lock nut 17 constitute a second moving member.

Further, an external thread 16 a is formed on the outer periphery of the adjusting screw 16 and is screwed to the internal thread 1 c of the housing 1. Nut 18 screwed into male thread 16a
Has a screw lock function. As is clear from FIG. 1, there is a predetermined clearance between the inner ring of the lower bearing 15 and the pinion teeth 3a of the output shaft 3, and the output shaft 3
, The lower bearing 15 is allowed to move in the axial direction.

A substantially tubular movable sleeve 19 is provided around the output shaft 3. The upper end of the movable sleeve 19 is in contact with the outer ring 14 a of the upper bearing 14, and the lower end is in contact with the bottom of the adjusting screw 16.
Around the rack shaft 11 of the movable sleeve 19, the rack shaft 11
A notch 19a is formed which is larger than the cross section of the pinion 3a, so that even when the movable sleeve 19 moves, the engagement between the pinion gear 3a and the rack teeth 11a is not hindered. In the vicinity of the lower end of the movable sleeve 19, a vertical groove 19b extending a predetermined distance in the axial direction is formed, and the detent pin 20 implanted in the housing 1 is inserted into the vertical groove 19b. . Thereby, the movable sleeve 19 is connected to the housing 1.
Can move in the axial direction, but cannot rotate relatively. Note that the adjusting screw 16 and the movable sleeve 19 constitute a first moving member.

An electric motor 21 is provided at the left end of the housing 1.
Is attached. The electric motor 21 includes a bearing 22,
A rotation shaft 21 a is rotatably supported by the housing 1 with respect to the housing 1. A large-diameter portion 21b is formed at the center of the rotating shaft, with both sides sandwiched by bearings 22 and 23. The right side of the bearing 23 is in contact with a step 1e formed in the housing 1. On the other hand, the left side of the bearing 22 is in contact with the tubular screw member 24. By screwing a male screw portion 24a formed on the outer periphery of the tubular screw member 24 into a female screw portion 1d formed on the housing 1, the bearings 22, 2 are formed.
3 is attached to the housing 1 so as to be immovable in the axial direction. The nut 25 screwed into the male screw portion 24a has a screw lock function. The electric motor 21 is connected to a drive device (not shown). The drive device inputs information such as the output of the potentiometer 10 and the vehicle speed, supplies predetermined electric power to the electric motor, and supplies an appropriate auxiliary torque. To be generated.

The rotation shaft 21a is disposed so that its axis is orthogonal to the output shaft 3, and the rotation shaft 21a
A small bevel gear 21c, which is a small gear engaged with the large bevel gear 13, is formed at the tip of the small bevel gear 21c. The large bevel gear 13 and the small bevel gear 21c form a bevel gear mechanism.

Next, the operation of the embodiment of the present invention will be described below. When the vehicle is in a straight running state and no steering force is input to the input shaft 2 via a steering wheel and a steering shaft (not shown), the slider 6 does not move relative to the input shaft 2 and the potentiometer 10 outputs No signal is generated, and the electric motor 21 does not generate auxiliary steering torque.

When the driver steers a steering wheel (not shown) when the vehicle is about to make a curve, the torsion bar 5 twists according to the steering force, and the rotational phase difference between the input shaft 2 and the output shaft 3 is increased. Occur. Based on the rotational phase difference, the slider 6 moves up and down with respect to the input shaft 2 in a known manner, and the potentiometer 10 outputs a signal according to the moving direction and amount of the slider 2. Based on this signal,
The electric motor 21 generates an auxiliary steering force.

Next, an operation for appropriately setting the backlash between the bevel gears will be described. First, when the backlash is to be appropriately set at the time of assembling, the adjusting screw 16 is tightened or loosened while the lock nut 17 and the nut 18 are removed so that the movable sleeve 19 is moved upward or downward. Since the outer ring of the upper bearing 14 is loosely fitted to the housing 1 and the inner ring of the bearing 4 is loosely fitted to the input shaft 2, the input shaft 2, the output shaft 3, and the large bevel gear 13 are similarly fitted. The lower bearing 15 moves upward or downward together with the upper bearing 14. By this operation, the distance between the tooth surfaces of the small bevel gear 21c and the large bevel gear 13 changes, and the backlash is adjusted. Even if the adjusting screw 16 is rotated, the action of the detent pin 20 causes
The movable sleeve 19 does not rotate. Finally lock nut 1
7 and nut 18 are tightened. By tightening the lock nut 17 with an appropriate torque, the inner ring and the outer ring of the upper bearing 14 and the lower bearing 15 move in the direction of pressing the ball, thereby removing play in the bearing while allowing rotation. As a result, the play of the output shaft 3 in the axial direction is reduced.

Next, in order to reduce the backlash after assembly, the nut 18 is removed, the adjusting screw 16 is tightened, and the movable sleeve 19 is moved upward. Thereby, the input shaft 2, the output shaft 3, the large bevel gear 13
The lower bearing 15 moves upward together with the upper bearing 14. By this operation, the distance between the tooth surfaces of the small bevel gear 21c and the large bevel gear 13 is reduced, and the backlash is reduced.

On the other hand, if an attempt is made to increase the backlash after assembly, the nut 18 is loosened, and the adjusting screw 16 (right screw) is rotated to the left. Thus, the lower bearing 15, the output shaft 3, the input shaft 2, the large bevel gear 13, the upper bearing 14, and the movable sleeve 19 move downward integrally. With this operation, the distance between the tooth surfaces of the small bevel gear 21c and the large bevel gear 13 increases, and the backlash also increases. At this time, a relative slip is required between the movable sleeve 19 and the adjusting screw 16, but this can be sufficiently coped with by appropriately setting the preload amounts of the bearings 14 and 15. It is not necessary to loosen the lock nut 17 in principle at the time of backlash adjustment after assembly.

Although the present invention has been described in detail with reference to the embodiments, the present invention should not be construed as being limited to the above-described embodiments, and can be appropriately changed and improved without impairing the spirit thereof. Of course. For example, the bevel gear mechanism may be a hypoid gear instead of a bevel gear, or may be a simple bevel gear.

[0026]

As described above, according to the electric power steering apparatus of the present invention, the output shaft is driven in the axial direction through the rolling element of the first bearing and the inner ring by driving the first moving member. , So that the tooth surface of the small gear and the tooth surface of the large gear are close to each other.
After the outer ring of the second bearing abuts on the first moving member by the driving of the moving member, the outer ring of the first and second bearings is prevented from moving in the approaching direction. Further, since the inner rings of the first and second bearings are moved in a direction in which the inner rings approach each other, play generated in the first and second bearings is eliminated. Thus, by performing a simple operation with a simple configuration, the backlash of the bevel gear mechanism and the play of the bearing can be eliminated.

[Brief description of the drawings]

FIG. 1 is a sectional view of an essential part in an axial direction of an electric power steering device according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Housing 2 ... Input shaft 3 ... Output shaft 16 ... Adjustment screw 17 ... Lock nut 19 ...・ Movable sleeve

Claims (1)

(57) [Scope of request for utility model registration] An electric motor having a housing, a steering torque detecting means for detecting a steering torque generated in a steering system, a rotating shaft for generating a rotational force in accordance with a detection result of the steering torque detecting means, A transmission mechanism for transmitting the torque of the electric motor to the steering system, the transmission mechanism being connected to a small gear connected to a rotation shaft of the electric motor, and an output shaft of the steering system, and An electric power steering apparatus including a bevel gear mechanism that meshes with a large gear having an axis that is not parallel to the axis of the pinion, wherein the rotary shaft connected to the pinion is rotatable but cannot move in the axial direction. The gear is connected to the output shaft of the steering system so as to move in the rotational direction and the axial direction integrally with the output shaft of the steering system, and the output shaft is connected to the housing. versus Are supported by first and second bearings so as to be freely rotatable. Each bearing includes an outer ring, an inner ring, and a rolling element sandwiched between the two wheels. The outer race is supported so as to be movable in the axial direction with respect to the housing, and the inner race of the first bearing is restricted from moving relative to the output shaft at least in a direction away from the second bearing. The inner ring of the second bearing is supported so as to be movable in the axial direction with respect to the output shaft, and the outer ring of the first bearing is fixed to the housing. A first moving member that is driven to relatively move in the axial direction, and a second moving member that is driven to relatively move the inner ring of the second bearing relative to the output shaft in the axial direction. The first bearing is driven by driving the first moving member. The outer ring,
The output shaft is moved in the axial direction via the rolling element and the inner ring, whereby the tooth surface of the small gear and the tooth surface of the large gear are brought close to each other, and the driving of the second moving member is performed. Thus, after the outer ring of the second bearing abuts on the first moving member, the outer ring of the first and second bearings is prevented from moving in a direction in which the outer rings approach each other. An electric power steering device in which a play generated in the first and second bearings is removed by moving the inner rings of the first and second bearings in a direction in which the inner rings approach each other.