JP2000318626A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the assembling of a shaft having a major diameter key lock collar by providing a protruding part on either one of a first shaft and a second shaft, providing a recessed part to be slid and engaged with the protruding part in connection on the other shaft, and also providing a means for regulating the sliding resistance between the protruding part and the recessed part. SOLUTION: A female serration part 20a as recessed part is formed on the lower end inside of an input shaft 20. On the other hand, a male serration part 23a as protruding part is formed on the upper end outside of a sensor shaft 23. Further, a retainer ring 25 having a circumferentially partially cut ring shape and formed of spring steel is arranged on the outer circumference of the input shaft 20. According to this structure, since the sensor shaft 23 can be easily connected to the input shaft 20 after the sensor shaft 23 as the first shaft is inserted to a lower housing, a large-sized key lock collar can be mounted on the circumference of the input shaft 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an electric power steering apparatus.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of improving fuel efficiency, an electric power steering apparatus capable of generating an auxiliary steering force without removing power directly from an engine is mounted on a vehicle with a small displacement, particularly from a viewpoint of improving fuel efficiency. It is becoming. As one type of such an electric power steering apparatus, an auxiliary steering force output portion is provided at a lower portion of a column tube, and an input shaft extending downward in the column tube is directly connected to the auxiliary steering force output portion. There is something.

FIG. 5 shows a conventional example of such an electric power steering apparatus. In FIG. 5, in such a configuration, a torsion bar 105 is provided between an input shaft 102 that receives a steering force from a steering wheel (not shown) and an output shaft 103 that transmits the steering force to the wheels.
By detecting the twist of the torsion bar 105, the steering torque required for the auxiliary steering force output control can be detected.

[0004] A detecting device 106 for detecting the steering torque includes:
For example, it is disclosed in JP-A-9-101212,
Sensor housing 101a below column tube 101
The impedance of the coil 106c is changed according to the steering torque applied to the input shaft 102, and the steering torque is detected based on the impedance.

[0005] The input shaft 102 is assembled by inserting the column tube 101c into the column tube 101c from the sensor housing 101a side after the column tube 101c is fixed to the sensor housing 101a and the coil 106c of the detecting device 106 is assembled. It is supposed to be.

[0006]

By the way, in order to prevent theft of the vehicle, the vehicle is usually provided with an anti-theft mechanism. According to such an anti-theft mechanism, when the driver removes the key, the input shaft is fixedly rotated with respect to the column tube, so that the steering wheel cannot be rotated, or the input shaft is provided with resistance to rotation, and the steering is performed. It requires a lot of power to do it.

[0007] Such an anti-theft mechanism includes a cylindrical member called a key lock collar provided at the center of the input shaft. A hole is formed on the outer peripheral surface of the key lock collar, and when the driver pulls out the key,
A shaft extending in the radial direction from the column tube side,
The rotation of the input shaft is restricted by fitting into the hole of the key lock collar.

However, in FIG. 5, for example, when the key lock collar 110 is attached to the center of the input shaft 102, in order to insert the key lock collar 110 into the column tube 101c, the detection device already attached to the sensor housing 101a is used. 106 must pass through the coil 106c. Therefore, the outer diameter φB of the key lock collar needs to be smaller than the outer diameter φA of the coil 106c (φB <φA).

By the way, in order to secure the function of restricting the rotation of the key lock collar 110, it is preferable that its outer diameter is large. Further, a resistance ring or the like for applying resistance may be provided between the key lock collar 110 and the input shaft 102. In such a case, the outer diameter of the key lock collar 110 is often larger. Therefore, the key lock collar 1 having such a large diameter is used.
Some measure is needed to arrange the coil 10 inside the small-diameter coil 106c.

In order to solve such a problem, the detection device 106 is simply used.
Although it is considered that the inner diameter of the coil 106c should be increased, a new design of the coil requires a considerable amount of time and a new problem that the cost of the electric power steering apparatus increases. On the other hand, there is a thought that the input shaft 102 may be divided into two parts, inserted in the directions facing each other, and coupled using a fastening means such as a bolt in the housing. However, there is a problem in that connecting the shafts to each other in the housing is considerably troublesome.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a steering apparatus which can easily assemble an input shaft having a large diameter key lock collar or the like without significantly increasing the cost.

[0012]

In order to achieve the above object, a steering device according to the present invention comprises a housing means comprising a sensor housing and a column tube, and a detecting device provided in the sensor housing and having an opening. A first shaft, one end of which can be inserted into the opening of the detection device, a second shaft, and the one end of the first shaft;
Connecting means for connecting the second shaft in the column tube so as to be integrally rotatable, wherein the connecting means is provided on one of the first shaft and the second shaft. A convex portion, a concave portion provided on the other side and slidingly engaging with the convex portion when connecting the first shaft and the second shaft, and a convex portion and the concave portion; Adjusting means for adjusting the sliding resistance generated therebetween.

[0013]

According to the electric power steering apparatus of the present invention, the connecting means is provided on one of the first shaft and the second shaft and the other, and is provided on the other of the first shaft and the second shaft. A concave portion that slides and engages with the convex portion when connecting the second shaft and the second shaft, and adjusting means that adjusts a sliding resistance generated between the convex portion and the concave portion; Has
After inserting the first shaft into the opening of the detection device,
The first shaft and the second shaft can be easily connected by the connecting means, so that if the first shaft and the second shaft are integral with each other, the opening is formed. For example, a large key lock collar or the like, which cannot be attached because it cannot pass through, can be attached to the outer periphery of the second shaft. The adjusting means may be, for example, a retainer ring or a resin-coated serration.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described in detail below with reference to the drawings. FIG. 1 is an axial sectional view showing an electric power steering apparatus according to a first embodiment of the present invention.

In FIG. 1, a lower housing 1 comprising a sensor housing 1a and a lid member 1b arranged below.
The output shaft 3 extends in the vertical direction. The upper end of the lower housing 1 and the lower end of the elongated cylindrical column tube 1c are connected by bolts 24, and the inside of the column tube 1c is connected to the input shaft 20 and the sensor connected in series as described later. The shaft 23 extends. Lower housing 1 and column tube 1
and c form housing means.

A steering wheel (not shown) is mounted on the upper end of the hollow input shaft 20. The lower housing 1 and the column tube 1c are attached to a chassis (not shown) via a bracket (not shown).

The input shaft 20 is rotatably supported on the column tube 1c by a bearing 22, and the output shaft 3 is rotatably supported on the lower housing 1 by bearings 14 and 15. The upper end of the torsion bar 5 extending in the hollow output shaft 3 is connected to the lower end of the sensor shaft 23,
Is connected to the lower end of the output shaft 3.

A detection device, ie, a torque sensor 6, for detecting a steering torque is provided around the upper end of the output shaft 3 based on the fact that the torsion bar 5, which is an elastic deformation member, is twisted in proportion to the torque received. This torque sensor 6 is a rotary type non-contact torque sensor,
Two coil bobbins 6a around which coils are wound, two cylindrical coil yokes 6b accommodating the coil bobbins 6a inside, a circuit board 6c for detecting a current generated in the coils, and a sleeve 6e attached to the output shaft 3. It is composed of

A cylindrical recess 1d is formed on the inner peripheral surface of the lower housing 1, and a coil yoke 6b is fitted into the recess 1d. The torque sensor 6 detects the relative angular displacement between the sensor shaft 23 and the output shaft 3 based on the torsion of the torsion bar 5 by a coil as a change in impedance in a predetermined magnetic circuit, and outputs it as an electric signal to a control circuit (not shown). Since it is disclosed in, for example, JP-A-9-101212,
Details are not described below.

A worm wheel 13 is fixedly mounted on the outer periphery of the central portion of the output shaft 3 by press fitting or the like.
The worm wheel 13 meshes with a worm 30a connected to a rotating shaft 30 of an electric motor (not shown). This electric motor is connected to a control circuit (not shown),
The control circuit inputs information such as the output of the torque sensor 6 and the vehicle speed, and supplies predetermined electric power to the electric motor to generate an appropriate auxiliary torque.

An upper bearing 14 is fitted above the worm wheel 13 on the output shaft 3, and a lower bearing 15 is fitted below the worm wheel 13. The inner ring of the lower bearing 15 is attached to the output shaft 3 by screwing the lock nut 17 to the output shaft 3. The lower end of the output shaft 3 is connected to a steering device (not shown) such as a rack and pinion mechanism.

FIG. 2 is a view of the configuration of FIG. 1 cut along the line II-II and viewed in the direction of the arrow. The hollow input shaft 20 is provided with four elongated cutouts 20b that extend from the lower end in FIG. 1 in parallel with the axis. Further, a female serration portion 20 a as a concave portion is formed on the inner periphery of the lower end of the input shaft 20. On the other hand, a male serration 23a as a convex is formed on the outer periphery of the upper end of the sensor shaft 23 in FIG. By engaging the male serration portion 23a with the female serration portion 20a, the input shaft 20 and the sensor shaft 23 are connected to each other so as not to rotate relatively.

Further, on the outer periphery of the input shaft 20, a ring shape is formed by cutting a part in the circumferential direction.
A retainer ring 25 made of spring steel or the like is arranged. The retainer ring 25 is, due to its elastic force,
The female serration portion 20a of the input shaft 20 is
The sensor shaft 23 is pressed toward the male serration portion 23a.

In this embodiment, a key lock collar 26 having a cylindrical shape for preventing vehicle theft is integrally attached to a central outer periphery of the input shaft 20, and its outer diameter is φD. I have.

Next, the operation of the embodiment according to the present invention will be described below with reference to FIG. If the vehicle is running straight and no steering force is input to the input shaft 20 via a steering wheel (not shown) and the steering shaft 20 (not shown), the torque sensor 6 does not generate an output signal. Does not generate force.

When the driver steers a steering wheel (not shown) when the vehicle is going to make a curve, the torsion bar 5 is twisted in accordance with the steering force transmitted via the input shaft 20, and the output from the sensor shaft 20 is reduced. Relative rotation occurs with the shaft 3. The torque sensor 6
A signal is output according to the direction and amount of the relative rotation.
Based on this signal, the electric motor rotates to generate an auxiliary steering force. The rotation of the electric motor is reduced by the worm gear mechanisms 30a and 13 and transmitted to the output shaft 3,
This supports the operation of the steering mechanism (not shown).

Next, an assembling mode of the electric power steering apparatus according to the present embodiment will be described. First,
Referring to FIG. 1, a torque sensor 6 is incorporated in a concave portion 1 d in the lower housing 1 before being connected to the column tube 1 c. Here, the inner diameter of the coil of the torque sensor 6 of the present embodiment is φC, and the relationship with the outer diameter φD of the key lock collar 26 satisfies φC <φD. Therefore, according to the dimensional relationship, the input shaft 20 to which the key lock collar 26 is attached cannot be inserted from the lower housing 1 side in which the torque sensor 6 is incorporated in a state where the input shaft 20 is connected to the sensor shaft 23.

Therefore, in the present embodiment, the sensor shaft 23 as the first shaft is independently inserted into the lower housing 1 before being coupled to the input shaft 20 as the second shaft. . The maximum outer diameter of the sensor shaft 23 is the coil inner diameter φC of the torque sensor 6.
Because it is smaller, such insertion is easily performed. Thereby, the upper end of the sensor shaft 23 is
It will protrude upward from inside.

In parallel with the above steps, a key lock collar 26 is attached to the center of the input shaft 20, a retainer ring 25 is fitted to the lower end thereof, and then the input shaft 20 is inserted into the column tube 1c. The assembly thus formed is integrally lowered from above toward the lower housing 1, and the male serration portion 23a of the sensor shaft 23 projecting upward.
The female serration portion 20a of the input shaft 20
And slide relatively.

At this time, since the slit 20b is formed on the input shaft 20, the lower end of the input shaft 20 can be easily opened outward in the radial direction. The male serration 23a and the female serration 20a can be easily fitted even if there is an inclination or misalignment.

On the other hand, once the male serration portion 23a and the female serration portion 20a have been fitted, the male serration portion 23a is elastically applied by the retainer ring 25.
a and the female serration portion 20a are pushed in a direction in which they approach each other, so that play between them is eliminated.

Since the elastic force of the retainer ring 25 can be changed by changing the thickness of the retainer ring 25, the pushing load when fitting the input shaft 20 to the sensor shaft 23 is adjusted by changing the applied elastic force. it can. That is, the retainer ring 25 constitutes an adjusting unit.

Thereafter, the column tube 1c is connected to the lower housing 1 by using the bolt 24, and other components are assembled, whereby the assembly of the electric power steering device is completed.

As described above, according to the present embodiment, the input shaft 20 having the key lock collar 26 having an outer diameter φD larger than the inner diameter φC of the coil, which is impossible with the prior art, can be easily connected to the column tube 1c. Can be incorporated within.

FIG. 3 shows a modification of the present embodiment.
It is sectional drawing similar to. 3 differs from the embodiment of FIG. 1 in the shape of the column tube. That is, the steering device shown in FIG. 3 is a so-called collapsible steering device, and functions to reduce the impact on the driver by reducing the length of the column tube at the time of a vehicle collision.

Specifically, the column tube has a shape in which a lower column tube 1c and an upper column tube 1e are connected in a nested manner. When a large load is applied in the vertical direction due to a vehicle collision or the like, the connection between the lower column tube 1c and the upper column tube 1e is disconnected, and the column tube is contracted.

As is apparent from the above description, the electric power steering apparatus according to the present embodiment can be changed to the type shown in FIG. 1 or the type shown in FIG. 3 by changing the column tube. Can be
As a result, parts can be shared between different vehicle types,
This will contribute to cost reduction. In addition, as another modified example, by replacing the column tube with a telescopic mechanism, a telescopic type steering device can be obtained.

FIG. 4 is a sectional view similar to FIG. 1 showing the second embodiment. The second embodiment differs from the embodiment of FIG. 1 in that instead of providing a retainer ring and a slot, a resin coating is applied to a serration portion as an adjusting means.

More specifically, the male serration portion 23a
And female serration 20a (only one is acceptable)
In addition, a resin capable of reducing the friction coefficient of the surface is entirely coated. According to the present embodiment,
Since the coated resin reduces the sliding resistance when the male serration portion 23a and the female serration portion 20a are fitted, the assembly can be easily performed without providing a slot or the like.

Although the present invention has been described in detail with reference to the exemplary embodiments, the present invention should not be construed as being limited to the above-described exemplary embodiments, but may be modified as appropriate without departing from the spirit of the present invention. Of course, it can be improved. For example, according to the prior art, the bearing that rotatably supports the input shaft was in a clearance-fitted state with respect to the input shaft, but since the input shaft can be previously assembled to the column tube and the bearing,
The bearing can be interference fitted to the input shaft. Alternatively, a male serration may be formed on the input shaft, and a female serration may be provided on the hollow sensor shaft. In any combination,
Since the inner shaft of the column-side bearing and the input shaft can be tightly fitted, the rattling of the steering wheel can be reduced.

[0041]

According to the electric power steering apparatus of the present invention, the connecting means is provided on one of the first shaft and the second shaft and the other is provided on the other. When connecting a shaft and the second shaft, a concave portion that slides and engages with the convex portion, and an adjusting unit that adjusts sliding resistance generated between the convex portion and the concave portion. Since the first shaft is inserted into the opening of the detection device, the first shaft and the second shaft can be easily connected by the connecting means, whereby the second shaft can be connected. If the first shaft and the second shaft are integral with each other, a large key lock collar, for example, which cannot be mounted because it cannot pass through the opening, is also mounted on the outer periphery of the second shaft. Can be.

[Brief description of the drawings]

FIG. 1 is an axial sectional view showing an electric power steering apparatus according to a first embodiment of the present invention.

FIG. 2 is a view of the configuration of FIG. 1 cut along a line II-II and viewed in a direction of an arrow.

FIG. 3 is a cross-sectional view similar to FIG. 1, illustrating a modification of the present embodiment.

FIG. 4 is a sectional view similar to FIG. 1, showing a second embodiment.

FIG. 5 is a diagram showing a conventional example of an electric power steering device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower housing 1c Column tube 3 Output shaft 6 Torque sensor 20 Input shaft 20a Female serration part 20b Slot 23 Sensor shaft 23a Male serration part 25 Retainer ring 26 Key lock collar

Claims (1)

[Claims] 1. A housing means comprising a sensor housing and a column tube, a detection device provided in the sensor housing and having an opening, and a first shaft one end of which is insertable into the opening of the detection device. A second shaft; and a connecting means for connecting the one end of the first shaft and the second shaft in the column tube so as to be able to rotate integrally with the second shaft. A protrusion provided on one of the first shaft and the second shaft, and a protrusion provided on the other, for connecting the first shaft and the second shaft with respect to the protrusion. An electric power steering apparatus, comprising: a concave portion that slides and engages with the first portion; and an adjusting unit that adjusts sliding resistance generated between the convex portion and the concave portion.