JP2003028180A - Joint mechanism and steering auxiliary device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-priced joint mechanism capable of connecting an output shaft of an electric motor to a rotary shaft to be driven for rotation by the output shaft without generating the striking noise, and to provide a steering auxiliary device using the same. SOLUTION: The inner periphery of a joint 81 is provided with a spline hole (engagement part) 81a to be engaged with a worm shaft 70 for integral rotation, and a buffer agent 83 having viscosity is interposed between the spline hole 81a and the worm shaft 70. A seal member 84 is provided at an end of the joint 81 to seal between the joint 81 and the worm shaft 70.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint mechanism for connecting an output shaft and a rotary shaft of an electric motor and a steering assist device using the joint mechanism.

[0002]

2. Description of the Related Art Conventionally, as a steering assist device for an automobile,
As shown in FIG. 5, a first steering shaft 102 to which steering wheels (handles) 101 are attached, and a second steering shaft 104 provided in series below the first steering shaft 102 via a torsion bar 103. Based on the relative rotational displacement of the first steering shaft 102 and the second steering shaft 104,
The steering torque is detected by the torque sensor 105, and the electric motor 106 for assisting steering is driven based on the detection result of the torque sensor 105, the vehicle speed, the steering angle of the steering wheel, etc., and the rotation of the electric motor 106 is reduced by the speed reduction mechanism 109.
There is provided a device that assists the manual steering force by the steered wheels 101 by decelerating by and transmitting to the second steering shaft 104.

As shown in FIG. 6, the speed reduction mechanism 109 is made of a worm shaft 107 provided with a worm, and is made of a synthetic resin which is integrally rotatably attached to the second steering shaft 104 while being engaged with the worm shaft 107. Worm wheel 10
And one end of the worm shaft 107 is integrally rotatably connected to the output shaft 106a of the electric motor 106 via a joint 111.

The joint 111 is generally used in which a spline hole 113 is formed on the inner periphery of one end side of a cylindrical body 112, and a spline shaft 114 formed at one end of the worm shaft 107 is formed in the spline hole 113. The output shaft 106a of the electric motor 106 at the other end.
The output shaft 10 is fitted to the output shaft 10 so as to be integrally rotatable.
The rotation of 6a can be transmitted to the worm shaft 107.

[0005]

However, in the above steering assist device, the spline hole 1 of the joint 111 is used.
A rattling noise was generated due to the backlash (meshing error) of the meshing portion of the worm shaft 107 with the spline shaft 114 of the worm shaft 107, which propagates into the vehicle and may cause discomfort to the driver and passengers. . Therefore, spline hole 1
The accuracy of the spline hole 113 and the spline shaft 114 is improved in order to reduce the play in the meshing portion between the spline shaft 13 and the spline shaft 114.

However, in order to improve the accuracy of the spline hole 113 and the spline shaft 114, there is a problem that the cost increases. Furthermore, spline hole 11
When the spline shaft 114 is fitted to the shaft 3 with high accuracy, the eccentricity or inclination between the worm shaft 107 and the output shaft 106a makes it difficult to connect the shafts 106a and 107, or causes shaft runout. Noise is generated, and the rotation resistance of the worm shaft 107 increases. The present invention has been proposed in view of the above circumstances, and it is possible to connect an output shaft of an electric motor and a rotation shaft that is rotationally driven by the output shaft at low cost and without producing a tapping sound. An object of the present invention is to provide a joint mechanism and a steering assist device using the joint mechanism.

[0007]

The present invention employs the following means in order to achieve the above object. That is, the joint mechanism of the present invention is a joint mechanism that integrally rotatably connects the rotary shaft to the output shaft of the electric motor, is formed on the inner circumference of the joint, and is engaged with the rotary shaft so as to be integrally rotatable. A means for interposing a viscous cushioning agent between the engaging portion and the rotating shaft and providing a seal member for sealing between the joint and the rotating shaft at the end of the joint is adopted. (Claim 1).

According to the joint mechanism constructed as described above, since the cushioning agent is interposed between the engaging portion and the rotary shaft, the shock is caused due to the looseness between the engaging portion and the rotary shaft. It is possible to suppress the generation of sound. As a result, the play between the engagement portion and the rotary shaft can be increased, so that the eccentricity and inclination between the output shaft of the electric motor and the rotary shaft can be absorbed or allowed. Further, the seal member can prevent the buffer agent from leaking out from the inside of the joint.

Further, it is preferable that an axial groove portion for venting air inside the joint is provided on the inner circumference of the joint (claim 2). In this case, when connecting the rotary shaft and the output shaft to the joint, the air inside the joint can be extracted from the groove.

Further, in the steering assist device of the present invention, the rotation of the electric motor is transmitted to the steering shaft via a worm shaft as a rotating shaft provided with a worm and a worm wheel meshing with the worm of the worm shaft. In the steering assist device that assists the steering by doing so, a means is employed in which the output shaft of the electric motor and the worm shaft are connected using the joint mechanism according to claim 1 or 2. Claim 3).

According to the steering assist device constructed as described above, since the cushioning agent is interposed between the engaging portion and the worm shaft, there is a play between the engaging portion and the worm shaft. It is possible to suppress the generation of tapping sound. As a result, the play between the engaging portion and the worm shaft can be increased, so that eccentricity and inclination between the output shaft of the electric motor and the worm shaft can be absorbed or allowed. Further, the seal member can prevent the buffer agent from leaking out from the inside of the joint.

Further, it is preferable that the worm shaft is biasedly supported toward the worm wheel, and the worm shaft is biased toward the worm wheel by a biasing means (claim 4). In this case, since the worm shaft can be biased toward the worm wheel, it is possible to absorb or allow the eccentricity and inclination of the worm shaft with respect to the output shaft of the electric motor, and the worm shaft toward the worm wheel. It can be moved easily. Therefore, the urging means can surely move the worm shaft following the wear of the worm wheel.

[0013]

1 is a cross-sectional view showing an electric motor and a speed reduction mechanism portion in an embodiment of a steering assist device according to the present invention, and FIG. 2 (a) is a joint mechanism shown in FIG. It is an expanded sectional view, (b) is IIb-II of (a).
FIG. 3 is a sectional view taken along line b, and FIG. 3 is a sectional view showing the overall structure of the steering assist device. The joint mechanism and the steering assist device using the joint mechanism will be described below with reference to the drawings. As shown in FIG. 3, the steering assist device includes a first steering shaft 2 to which steering wheels 1 are attached at the upper end, and a cylindrical second steering shaft 2 connected to the lower end of the first steering shaft 2 via a torsion bar 3.
The steering shaft 4, a torque sensor 5 that detects a steering torque based on the relative rotational displacement of the first steering shaft 2 and the second steering shaft 4, and the torque sensor 5 is driven based on the detection results of the torque sensor 5 and the like. An electric motor 6 for steering assistance, and a reduction mechanism 7 for decelerating the rotation of the electric motor 6 and transmitting the decelerated rotation to the second steering shaft 4.
It has and.

The first steering shaft 2 is supported while being surrounded by the first steering column 9 and the second steering column 10. The first steering column 9 is attached to the vehicle body A via the bracket 12. There is. The torque sensor 5 is housed in the sensor housing H1, the reduction mechanism 7 is housed in the gear housing H2, and the electric motor 6 is housed in the gear housing H2.
Is attached to.

The first steering shaft 2 has a cylindrical first shaft 2a having the steered wheels 1 attached to the upper end thereof, and a lower end of the first shaft 2a is allowed to move in the axial direction. In this state, the rod-shaped second shaft body 2b is fitted so as to be integrally rotatable, and the cylindrical third shaft body 2d is connected to the second shaft body 2b by the pin 2c. The first shaft body 2a has a cylindrical first steering column 9 with an intermediate portion interposed by a bearing 13.
It is rotatably supported by. In addition, the first and second
A buffer member 2e made of synthetic resin is provided between the shafts 2a and 2b for absorbing the impact energy acting on the steered wheels 1 from the driver at the time of a collision of the automobile. Further, the torque sensor 5 is arranged between the third shaft body 2d and the second steering shaft 4.

The upper end of the second steering column 10 is slidably fitted in the first steering column 9 and the lower end thereof is fitted in the sensor housing H1 to absorb the impact energy. The first steering column 9 can be moved in the axial direction with respect to the second steering column 10. A torsion bar 3 is introduced inside the second steering shaft 4, and a lower end portion of the second steering shaft 4 is integrally and rotatably connected to the torsion bar 3 by a pin 4a. The axial middle portion of the second steering shaft 4 has a pair of bearings 14, 1
The worm wheel 72 is rotatably supported by the gear housing H2 through the bearing 5, and the inner circumference of the worm wheel 72 is integrally rotatably fitted between the bearings 14 and 15b.

As shown in FIG. 1, the reduction mechanism 7 includes a joint mechanism 8 of the present invention on the output shaft 60 of the electric motor 6.
And a worm wheel 70 that is fitted to the second steering shaft 4 so as to be integrally rotatable.
2 and. A worm 71 is integrally formed at an axially intermediate portion of the worm shaft 70, and the worm 71 is meshed with a worm wheel 72. Therefore, the rotation of the output shaft 60 of the electric motor 6 can be decelerated by the worm shaft 70 and the worm wheel 72 and transmitted to the second steering shaft 4. The rotation of the second steering shaft 4 is transmitted to, for example, a rack and pinion type steering mechanism connected to wheels via a universal joint J (see FIG. 3).

The worm shaft 70 is arranged in a state of being orthogonal to the axis of the second steering shaft 4, and one end and the other end of the worm shaft 70 are respectively interposed by the first and second bearings 16 and 17, respectively. First and second bearing holes 91, 9 of the housing H2
It is rotatably supported by 2 (see FIG. 1). First above
The bearing 16 is formed of a rolling bearing, one end of the worm shaft 70 is press-fitted into the inner ring, and the outer ring is inserted into the first bearing hole 91. Also, this first
In the bearing hole 91, a cylindrical screw body 18 is screwed into contact with the outer ring of the first bearing 16 to prevent rattling of the worm shaft 70 in the axial direction. The second bearing 17
Is composed of a metal bearing and has a second bearing hole 92 so that it can be biased toward the worm wheel 72.
Is attached to. That is, as also shown in FIG. 4, a gap 92a is provided between the inner rear portion of the second bearing hole 92 and the second bearing 17, and the second bearing 17 is warmed by the gap 92a. It can be moved to the wheel 72 side. When the second bearing 17 is biased toward the worm wheel 72, the bias on the one end side of the worm shaft 70 is allowed due to the rattling due to the radial clearance of the first bearing 16.

The plug 3 is provided on the opening side of the second bearing hole 92.
4 is screwed into the plug 34 and the second bearing 17
Between the second bearing 17 and the worm wheel 72.
Compression coil spring 3 as a biasing means for constantly biasing in the direction
2 is interposed in an elastically contracted state. In the case of the figure,
The compression coil spring 32 is housed inside a bottomed cylindrical projection 17 b that projects from the outer circumference 17 a of the second bearing 17. The biasing force of the compression coil spring 32 is adjusted to an optimum value by adjusting the screwing amount of the plug 34 into the second bearing hole 92. The plug 34 is fixed by a lock nut 35.

The joint mechanism 8 is shown in FIGS.
As shown in (a) and (b), a joint 81, a spacer 82 attached to this joint 81, a viscous cushioning agent 83 interposed between the joint 81 and the worm shaft 70, and a joint 81 An O-ring 84, which is provided at the end and seals between the joint 81 and the worm shaft 70, is provided. The joint 81 has a cylindrical shape, and a spline hole 81a as an engaging portion with which the worm shaft 70 is integrally rotatably engaged is formed on the inner periphery of the joint 81. A cylindrical hole 81b is formed at one end of the joint 81, and a spacer 82 is press-fitted therein. The spacer 82 has a cylindrical shape, and the output shaft 60 is press-fitted from one end side.

The buffering agent 83 is grease, molybdenum disulfide, silicon or the like, and is applied to the surface of the spline shaft 70b, for example.
It is interposed in the meshing portion between the tooth portion 70b1 of 0b and the spline hole 81a. In addition, the O-ring 84
Is mounted in an annular groove portion provided on the worm shaft 70, and when the worm shaft 70 is inserted into the joint 81, the worm shaft 70 contacts the inner peripheral surface portion 81c provided on the other end side of the joint 81. , Joint 81 and worm shaft 7
Seal between 0 and. When the spacer 82 is press-fitted into the joint 81 with the output shaft 60 press-fitted, the interior of the joint 81 is sealed and the buffer 83 is prevented from leaking from the interior of the joint 81 to the outside. Can be prevented.

A groove portion 81d having a semicircular cross section, for example, is axially provided in the inner peripheral surface portion 81c so as to communicate the inside and outside of the joint 81. By providing the groove portion 81d, the output shaft 60 and the worm shaft 7 are provided.
0, the joint 81, and the air inside the joint 81 surrounded by the spacer 82 are exhausted to the outside through a minute gap between the tooth portion 70b1 and the spline hole 82a and the groove portion 81d. Accordingly, while the air inside the joint 81 is discharged to the outside by the groove 81d, the work of connecting the worm shaft 70 and the joint 81, the joint 81 and the spacer 82, or the spacer 82 into which the output shaft 60 is press-fitted. Can be connected.

As described above, in the steering assist device of the present embodiment, the cushioning agent 83 is driven due to the play between the spline hole 81a (engaging portion) of the joint 81 and the spline shaft 70b due to its damper effect. It is possible to suppress the generation of sound. Thereby, the play between the spline hole 81a and the spline shaft 70b can be increased. As a result, since it is not necessary to finish the spline hole 81a and the spline shaft 70b with high precision, the cost can be reduced, and the eccentricity and inclination between the output shaft 60 and the worm shaft 70 can be absorbed or allowed. The work of connecting the output shaft 60 and the worm shaft 70 can be easily performed, and further, it is possible to prevent the occurrence of abnormal vibration due to shaft runout and the increase of the rotational resistance of the worm shaft 70. . Further, by sealing the joint 81 and the worm shaft 70 by the O-ring 84, it is possible to prevent the buffer agent 83 from leaking from the inside of the joint 81.

Further, in this embodiment, while the air inside the joint 81 is discharged to the outside by the groove 81d,
Since the connecting work between the worm shaft 70 and the joint 81 and the connecting work between the joint 81 and the spacer 82 or the spacer 82 into which the output shaft 60 is press-fitted can be performed, the joint work can be performed during each of these connecting works. Air can be prevented from being compressed inside 81, and each connecting operation can be performed more easily.

Further, in this embodiment, the worm shaft 70 is supported so as to be biased toward the worm wheel 72, and the worm shaft 70 is biased toward the worm wheel 72 by the compression coil spring 32. The worm 70a of 70 can be elastically pressed against the worm wheel 72. Further, in combination with the fact that the eccentricity and inclination between the output shaft 60 and the worm shaft 70 can be absorbed or allowed, the worm shaft 70 can be moved without difficulty toward the worm wheel 72. Therefore, when the worm 70a is used for a long period of time,
And even if the tooth surface of the worm wheel 72 is worn,
The worm 70a can be made to follow this wear reliably, and it is possible to effectively prevent the occurrence of backlash in the meshing portion of the worm 70a and the worm wheel 72. Further, when the synthetic resin worm wheel 72 expands due to water absorption, heat, or the like, it is possible to prevent the worm shaft 70 from escaping to the opposite side of the worm wheel 72 and increasing the rotational torque. Further, as described above, the worm 70a of the worm shaft 70 is attached to the worm wheel 7
Since it can be elastically pressed against 2, it is possible to adjust the play at the meshing portion of the worm 70a and the worm wheel 72 without being affected by the dimensional error of the parts including both when assembling them. .

In the above description, the structure using the joint 81 and the spacer 82 press-fitted into the joint 81 has been described, but the joint mechanism 8 of the present invention is not limited to this, and for example, The joint 81 and the spacer 82 may be integrally formed. Further, in the above description, the configuration in which the output shaft 60 is press-fitted into the spacer 82 has been described, but the spacer 82 may be any member that can be integrally rotatably engaged with the output shaft 60, and the tip of the output shaft 60 can be used. The spacer 82 may be provided with a spline hole or a serration hole that engages with a spline shaft or a serration provided in the portion. Further, in the above description, the configuration in which the worm shaft 70 and the joint 81 are connected by fitting the spline shaft 70b into the spline hole 81a has been described, but the present invention interposes the viscous buffer agent 83. The structure is not limited as long as it has an engaging portion that engages with the rotating shaft so as to rotate integrally therewith, and the worm shaft 70 and the joint 81 may be provided with serrations and serration holes, respectively, for connection.

The joint mechanism 8 of the present invention not only connects the output shaft 60 of the electric motor 6 and the worm shaft 70, but also connects the output shaft and various rotary shafts driven to rotate by the output shaft. It can also be suitably used as a mechanism.

[0028]

The present invention constructed as described above has the following effects. According to the joint mechanism of the first aspect, it is possible to suppress the tapping sound from being generated due to the backlash between the engaging portion and the rotating shaft of the cushioning agent. The play between them can be increased. As a result, it is possible to reduce the cost without having to finish the engaging portion and the rotary shaft with high accuracy, and it is possible to absorb or allow eccentricity and inclination between the output shaft and the rotary shaft.
Since it is not necessary to align the output shaft and the rotary shaft with high accuracy, the connection work between them can be easily performed. Further, since the buffering agent can be prevented from leaking from the inside of the joint, the effect of suppressing the tapping sound by the buffering agent can be maintained for a long period of time.

According to the joint mechanism of the second aspect, when the rotary shaft and the output shaft are connected to the joint, the air inside the joint can be discharged from the groove portion, so that the connecting work of the rotary shaft and the output shaft to the joint is performed. Can be performed more easily.

According to the steering assist device of the third aspect, it is possible to suppress the generation of a tapping sound due to the play of the cushioning agent between the engaging portion and the worm shaft. The play between the worm shaft and the worm shaft can be increased. As a result, it is not necessary to finish the engaging portion and the worm shaft with high accuracy, and it is possible to reduce the cost, and it is possible to absorb or allow the eccentricity and inclination between the output shaft and the worm shaft. The aligning work with the worm shaft can be simplified, and the connecting work between them can be easily performed correspondingly. Further, since the buffering agent can be prevented from leaking from the inside of the joint, the effect of suppressing the tapping sound by the buffering agent can be maintained for a long period of time.

According to the steering assist device of the fourth aspect, since the worm shaft can be biased toward the worm wheel,
Coupled with the fact that the eccentricity and inclination between the output shaft and the worm shaft can be absorbed or allowed, the worm shaft can be reasonably moved toward the worm wheel.
Therefore, the urging means can easily move the worm following the wear of the worm wheel, and can easily and surely prevent rattling between the worm and the worm wheel.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an electric motor and a deceleration mechanism portion in an embodiment of a steering assist device according to the present invention.

2A is an enlarged sectional view of the joint mechanism shown in FIG. 1, and FIG. 2B is a sectional view taken along line IIb-IIb of FIG.

FIG. 3 is a sectional view showing the overall structure of a steering assist device of the present invention.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a sectional view showing the overall structure of a conventional steering assist device.

FIG. 6 is a cross-sectional view showing an electric motor and a speed reduction mechanism portion in another conventional steering assist device.

[Explanation of symbols]

2 First steering shaft 4 Second steering shaft 6 electric motor 60 output shaft 70 Worm axis 70a warm 70b spline shaft 72 worm wheel 8 joint mechanism 81 joints 81a Spline hole (engagement part) 83 Buffer 84 O-ring (seal member)

Claims (4)

[Claims] 1. A joint mechanism for integrally connecting a rotating shaft to an output shaft of an electric motor, the engaging mechanism being formed on an inner circumference of the joint, and engaging the rotating shaft so as to rotate integrally. A joint mechanism characterized in that a viscous buffer is interposed between the rotary shaft and a seal member for sealing between the joint and the rotary shaft at the end of the joint. 2. An inner circumferential surface of the joint is provided with an axial groove portion for venting air inside the joint.
Joint mechanism described in. 3. A steering system for assisting steering by transmitting the rotation of an electric motor to a steering shaft via a worm shaft as a rotary shaft provided with a worm and a worm wheel meshing with the worm of the worm shaft. The auxiliary device, wherein the output shaft of the electric motor and the worm shaft are connected using the joint mechanism according to claim 1 or 2. 4. The steering assist device according to claim 3, wherein the worm shaft is supported so as to be biased toward the worm wheel, and the worm shaft is biased toward the worm wheel by biasing means.