JPH10329732A - Rack pinion type steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the fluctuation of the meshed state between a rack and a pinion and prevent the degradation of steering feeling by providing the rack meshed with the pinion on an output shaft transmitting the steering torque, and providing a means adjustably applying a pre-load to a bearing supporting the output shaft on a housing. SOLUTION: The steering torque generated by the steering of steering wheels is transmitted to a pinion 4 by a steering shaft 3, a rack 5 meshed with the pinion 4 is moved in the axial direction to steer wheels via a knuckle arm. A motor 8 is driven in response to the steering torque detected by a torque sensor 7, and its power is transmitted to an output shaft 3b via a worm 9 and a worm wheel 10 as steering auxiliary power. The other end of the output shaft 3b is protruded to the outside from a rack housing section 6, a pre-load adjusting nut 71 and a rock nut 72 are screwed to the protruded end, a pre-load is applied to ball bearings 26, 27, and the backlash of the steering shaft 3 is resolved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rack and pinion type steering device in which a rack is meshed with a pinion integrated with an output shaft for transmitting steering torque.

[0002]

2. Description of the Related Art An output shaft for transmitting a steering torque, a pinion integrated so as to rotate together with the output shaft, a rack meshing with the pinion, and a bearing mounted on the output shaft A rack-and-pinion type steering device has been conventionally used, which includes a housing that supports the vehicle via a pinion, and the vehicle is steered by the movement of the rack by the rotation of the pinion (Japanese Patent Application Laid-Open No. 9-20256). In the conventional rack and pinion type steering device, the meshing state of the rack and the pinion fluctuates due to the backlash in the axial direction of the output shaft,
There was a problem that the steering feeling was reduced.

In order to provide a steering assisting force in the rack-and-pinion type steering device, an input shaft connected to an output shaft so as to be axially displaceable and elastically relatively rotatable in accordance with a steering torque; A torque sensor for detecting a steering torque based on a change in magnetic resistance between a magnetic material member fixed to the magnetic member and a magnetic material member fixed to the output shaft, and a steering operation corresponding to the detected steering torque. Means for providing an assisting force is provided. However, when the output shaft rattles in the axial direction, the distance between the magnetic material member fixed to the input shaft and the magnetic material member fixed to the output shaft fluctuates. There is a problem that fluctuates from.

[0004] An actuator for generating a steering assist force corresponding to the detected steering torque in order to apply a steering assist force corresponding to the steering torque detected by the torque sensor, and a drive gear rotated by the steering assist force When,
A driven gear meshed with the drive gear and fitted to the output shaft is provided. If the backlash between the driving gear and the driven gear is not appropriate, the operation of replacing the driven gear is performed. However, when the output shaft is supported by a single housing, it is only possible to determine whether the backlash is appropriate only after the rack is engaged with the pinion. In this case, replacing the driven gear and optimizing the backlash requires a lot of troublesome disassembling and assembling work, including releasing the engagement between the pinion and the rack.

Conventionally, a retaining ring or a nut has been fitted to the output shaft to prevent the driven gear from being displaced in the axial direction. However, when a retaining ring or a nut is used, the axial dimension of the output shaft is correspondingly increased, and therefore, the steering device may not be arranged inside the vehicle body where space is limited.

In order to fail-safe when the output shaft of the actuator is locked, the driven gear is fitted to the output shaft via a torque limiter mechanism. When a steering torque greater than a preset limit torque is applied, the driven gear is driven. It is supposed to rotate relative to the output shaft. However, when a retaining ring is used to prevent the axial displacement of the driven gear, the frictional force that prevents relative slip between the driven gear and the retaining ring becomes excessive based on machining tolerances and assembly tolerances. In some cases, the torque limiter mechanism cannot function.

[0007] It is an object of the present invention to provide a rack and pinion type steering device which can solve the above problems.

[0008]

SUMMARY OF THE INVENTION A rack and pinion type steering apparatus according to the present invention includes an output shaft for transmitting a steering torque, a pinion integrated so as to rotate with the output shaft, and a rack meshing with the pinion. ,
It is characterized by comprising a housing for supporting the output shaft via a bearing, and a means for adjustingably applying a preload to the bearing. According to this configuration, by applying an appropriate preload to the bearing, the rattling of the output shaft in the axial direction is prevented, the fluctuation of the meshing state of the rack and the pinion is prevented, and the steering feeling is reduced. Can be prevented.

An input shaft connected to the output shaft so as to be relatively displaceable in the axial direction and to be relatively rotatable elastically in accordance with a steering torque, a magnetic member fixed to the input shaft, and fixed to the output shaft. It is preferable to include a torque sensor for detecting a steering torque based on a change in magnetic resistance between the magnetic member and the magnetic member, and a means for applying a steering assist force according to the detected steering torque. According to this configuration, the play between the magnetic member fixed to the input shaft and the magnetic member fixed to the output shaft is changed by preventing the output shaft from rattling in the axial direction. Can be prevented. As a result, it is possible to prevent the value detected by the torque sensor from varying from an appropriate value, and to apply an appropriate steering assist force.

In the present invention, the output shaft is the first shaft.
An outer ring displacement prevention portion that is supported by the housing via a rolling bearing and a second rolling bearing, and that prevents the outer rings of the two rolling bearings from being displaced toward each other; and an inner ring of the first rolling bearing, And a preload adjusting member screwed to the output shaft of the rolling bearing for preventing displacement in a direction away from the inner ring of the rolling bearing, and the preload adjusting member is screwed into the output shaft in accordance with an amount of screwing of the preload adjusting member into the output shaft. It is preferable that the inner ring of the second rolling bearing can be pushed toward the inner ring of the first rolling bearing. According to this configuration, the outer races of the two rolling bearings are prevented from being displaced toward each other by the outer race displacement prevention portion, and the inner race of the first rolling bearing is displaced in a direction away from the inner race of the second rolling bearing. Because it is blocked by the displacement block,
Depending on the amount of preload adjusting member screwed into the output shaft,
By pressing the inner race of the second rolling bearing toward the inner race of the first rolling bearing, a preload can be easily and adjustably applied to both rolling bearings.

A torque sensor for detecting the steering torque, an actuator for generating a steering assist force according to the detected steering torque, a drive gear rotated by the steering assist force, and meshed with the drive gear. And a driven gear fitted to the output shaft, wherein the housing includes a gear housing portion that covers the drive gear and the driven gear, and a rack housing that is separate from the gear housing portion and covers the pinion and the rack. And the output shaft is supported by the gear housing portion via the first rolling bearing, so that the driven gear can be meshed with the driven gear, and the output shaft is controlled by the gear housing portion. After supporting
The output shaft is moved to the second position by the rack housing portion.
It is preferable that the rack can be meshed with the pinion by supporting through a rolling bearing and connecting the rack housing to the gear housing. According to this configuration, before connecting the gear housing portion and the rack housing portion, the drive gear and the driven gear are engaged with the output shaft supported by the gear housing portion, so that the backlash between the two gears is reduced. It is possible to determine whether or not it is appropriate. Thus, the operation of replacing the driven gear for optimizing the backlash can be performed before the rack is engaged with the pinion. Therefore, the disassembly and assembly work for optimizing the backlash can be simplified.

A torque sensor for detecting the steering torque, an actuator for generating a steering assist force according to the detected steering torque, a drive gear rotated by the steering assist force, and meshed with the drive gear. And a driven gear fitted to the output shaft.The driven gear is fitted via a torque limiter mechanism such that the driven gear rotates relative to the output shaft when a steering torque greater than a preset limit torque acts on the output shaft. The driven gear is disposed between the inner ring of the first rolling bearing and the inner ring displacement prevention portion, and the inner ring of the first rolling bearing is moved by the inner ring displacement prevention portion via the driven gear. Preferably, displacement of the second rolling bearing away from the inner ring is prevented. According to this configuration, the axial displacement of the driven gear can be restricted by the inner ring of the first rolling bearing that supports the output shaft, so that a dedicated displacement restricting member such as a retaining ring is not required. Thus, the axial dimension of the output shaft can be reduced, and the size of the output shaft can be reduced. Further, by adjusting the preload applied to the first rolling bearing, it is possible to prevent the frictional force for preventing the relative slip between the inner ring of the first rolling bearing and the drive gear from becoming excessive. Thereby, the torque limiter mechanism can function properly.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

The rack and pinion type electric power steering apparatus shown in FIG. 1 has a steering wheel (not shown).
The steering torque generated by the steering of the vehicle is transmitted to the pinion 4 by the steering shaft 3 supported by the housing 1.
To communicate. Due to the rotation of the pinion 4 due to the steering torque, the rack 5 meshing with the pinion 4 moves.
The movement of the rack 5 changes the steering angle of wheels connected to the rack 5 via a knuckle arm or the like. The housing 1 is configured by connecting a gear housing 2 and a rack housing 6.

In order to apply a steering assisting force corresponding to the steering torque transmitted by the steering shaft 3, a torque sensor 7 for detecting the steering torque and a steering device driven in accordance with the detected steering torque. A motor (actuator) 8 that generates an assisting force, a worm (drive gear) 9 that is rotationally driven by the steering assisting force generated by the motor 8, and a worm wheel (driven gear) 10 that meshes with the worm 9 are provided. ing.

The worm 9 and the worm wheel 10 are covered by the gear housing 2. The pinion 4 and the rack 5 are covered by a rack housing 6 separate from the gear housing 2. The gear housing 2 is connected to the rack housing 6 and the sensor housing 21 of the torque sensor 7.

In the sensor housing 21, the steering shaft 3 is divided into an input shaft 3a and an output shaft 3b. A steering wheel is connected to one end of the input shaft 3a. One end of an output shaft 3b is fitted to the other end of the input shaft 3a via a bush 25 so as to be relatively rotatable.

The input shaft 3a is supported by the sensor housing 21 via a ball bearing 31. The output shaft 3b is connected to the gear housing 2
Are supported via first ball bearings (first rolling bearings) 26, and are supported by the rack housing portion 6 via second ball bearings (second rolling bearings) 27. The outer ring 26b of the first ball bearing 26 comes into contact with a step surface (outer ring displacement prevention portion) 2a formed on the inner periphery of the gear housing portion 2, thereby restricting displacement of the outer ring 26b toward the second ball bearing 27. You. The outer ring 27b of the second ball bearing 27 is provided with a step surface (outer ring displacement prevention portion) 6 formed on the inner periphery of the rack housing portion 6.
By being in contact with “a”, displacement toward the first ball bearing 26 is restricted. That is, the outer race 26b of the first ball bearing 26 and the second ball bearing 2
7 are restricted from being displaced toward each other.

The pinion 4 is integrally provided on the outer periphery of the output shaft 3b so as to rotate together with the output shaft 3b. The worm wheel 10 is fitted to the output shaft 3b via a torque limiter mechanism 11 described later. The worm 9 is supported inside the gear housing 2 via a bearing (not shown).

A torsion bar 23 is inserted along the center of each shaft 3a, 3b. One end of the torsion bar 23 is connected to the input shaft 3a by the pin 22 and the other end is connected to the output shaft 3b by the serration 24. Thus, the input shaft 3a and the output shaft 3b can be relatively rotated elastically according to the steering torque. Also, the torsion bar 23
And the output shaft 3b are connected by the serration 24, so that the input shaft 3a and the output shaft 3b can be relatively displaced in the axial direction.

The torque sensor 7 includes first and second detection coils 33 and 34 held by the sensor housing 21.
A first detection ring (magnetic material member) 36 made of a magnetic material and a third detection ring 38 made of a magnetic material fixed to the outer periphery of the input shaft 3a, and a magnetic material fixed to the outer periphery of the output shaft 3b. A second detection ring (a member made of a magnetic material) 37 made of a material is provided. One end face of the first detection ring 36 and one end face of the second detection ring 37 are disposed so as to face each other, and teeth 36a, 37a are respectively provided on one end faces of the detection rings 36, 37 along the circumferential direction. A plurality is provided. The other end surface of the first detection ring 36 and one end surface of the third detection ring 38 are arranged so as to face each other. A plurality of teeth 38a are provided on one end surface of the third detection ring 38 along the circumferential direction. No teeth are provided on the other end surface of the first detection ring 36. The first detection coil 33 is arranged so as to cover the space between the first detection ring 36 and the second detection ring 37, and the second detection coil 34 covers the space between the first detection ring 36 and the third detection ring 38. Are arranged as follows. Each detection coil 33, 34 is connected to a printed circuit board 41.

The signal processing circuit shown in FIG. 2 is formed on the substrate 41. That is, the first detection coil 33 is connected to the oscillator 46 via the resistor 45, the second detection coil 34 is connected to the oscillator 46 via the resistor 47, and the detection coils 33 and 34 are connected to the differential amplifier circuit 48. Is done. Thus, when the torsion bar 23 is twisted by the steering torque and the first detection ring 36 and the second detection ring 37 rotate relatively, the teeth 36a of the two detection rings 36, 37,
The area of the opposing portion 37a changes. The change in the area causes a change in the magnetic resistance of the first detection coil 33 with respect to the magnetic flux generated between the opposing teeth 36a and 37a. Therefore, the output of the first detection coil 33 changes based on the change, and corresponds to the output. The detected steering torque is detected. Further, the output fluctuation of the first detection coil 33 due to the temperature fluctuation is as follows.
It is set equal to the output fluctuation of the second detection coil 34 due to the temperature fluctuation. Thus, the output fluctuation of the first detection coil 33 due to the temperature fluctuation is canceled by the differential amplifier circuit 48, and the fluctuation of the detected value of the steering torque due to the temperature is compensated.

A signal corresponding to the steering torque output from the differential amplifier circuit 48 is sent to a control device (not shown) via a wiring 61. The control device drives the steering assist motor 8 according to the detected steering torque. The rotation of the motor 8 is transmitted to the output shaft 3b via the worm 9 and the worm wheel 10, so that a steering assist force is applied.

As shown in FIG. 3, the torque limiter mechanism 11 has a torque setting member 51 which is deformed in the radial direction by being sandwiched between the outer periphery of the output shaft 3b and the inner periphery of the worm wheel 10. The torque setting member 51
Are arranged in a circumferential groove 3h formed on the outer periphery of the output shaft 3b. As shown in FIGS. 4A and 4B, the torque setting member 51 includes a metal ring main body 51b having a split groove 51a, and a plurality of semi-cylindrical protrusions formed integrally with the main body 51b. A portion 51c. The protrusions 51c are arranged at regular intervals in the circumferential direction,
Projects radially outward. A radial force corresponding to the amount of radial deformation of each protrusion 51c acts on the output shaft 3b and the worm wheel 10. As such a torque setting member 51, for example, a tolerance ring (manufactured by Rencor Tolerance Rings, SV type) can be used.

FIG. 5 shows the relationship between the amount of radial deformation of the torque setting member 51 and the radial force. When the amount of radial deformation is equal to or less than a constant value δa, the radial force increases in proportion to the amount of radial deformation. In the region exceeding the fixed value δa, there is a region A in which the increasing ratio of the radial force to the radial deformation is smaller than the increasing ratio in the region less than the fixed value δa. The value δb in the area A exceeding the constant value δa
Is set to the amount of radial deformation of the torque setting member 51.

As shown in FIG. 3, the worm wheel 10 includes a ring-shaped flange (inner ring displacement preventing portion) 3d integrally formed on the outer periphery of the output shaft 3b and the first ball fitted to the output shaft 3b. Bearing 26
And the inner ring 26a. The inner ring 26a of the first ball bearing 26 is
The second ball bearing 27 is prevented from being displaced away from the inner ring 27a by the flange 3d. The axial displacement of the worm wheel 10 is restricted by the flange 3d and the inner ring 26a of the first ball bearing 26.

By applying a radial force corresponding to the amount of radial deformation of the torque setting member 51 to the steering shaft 3 and the worm wheel 10, the inner circumference of the torque setting member 51 and the outer circumference of the steering shaft 3 are moved. The torque can be transmitted between the steering shaft 3 and the worm wheel 10 due to the frictional resistance between the steering shaft 3 and the worm wheel 10 due to the frictional resistance between the outer circumference of the torque setting member 51 and the inner circumference of the worm wheel 10. The limit torque is determined according to the frictional resistance. In the present embodiment, the frictional resistance between the inner circumference of the torque setting member 51 and the outer circumference of the steering shaft 3 is made smaller than the frictional resistance between the outer circumference of the torque setting member 51 and the inner circumference of the worm wheel 10. You. The torque at which the inner circumference of the torque setting member 51 and the outer circumference of the steering shaft 3 relatively start to slip is the limit torque of the torque limiter mechanism 11. The limit torque is set to an appropriate value in advance by experiments. When a steering torque greater than the limit torque acts, the output shaft 3b and the worm wheel 10 rotate relative to each other.

As shown in FIG. 1, the rack 5 is supported by one end of a support yoke (rack support member) 66. The support yoke 66 is connected to the rack housing 6.
Are inserted movably in a direction approaching the rack 5 and a direction away from the rack 5. The movement of the support yoke 66 causes the pinion 4 and the rack 5 to move.
The machining error of the teeth and the bending of the rack 5 are absorbed, and the meshing between the rack 5 and the pinion 4 is facilitated. A coil spring 69 compressed by the other end of the support yoke 66 and a plug 68 screwed into the holding hole 65 is arranged. The support yoke 66 is pressed against the rack 5 by the elasticity of the spring 69. At the outer end of the plug 68, a tool engaging recess 68a is formed. By adjusting the amount of screwing of the plug 68 into the holding hole 65,
The elasticity of the spring 69 is adjusted, and the rack 5 and the pinion 4 are adjusted.
Is optimized. A lock nut 67 is screwed onto the outer periphery of the plug 68.

The other end of the output shaft 3b projects from an opening formed in the rack housing 6. A preload adjusting nut (preload adjusting member) 71 and a lock nut 72 are screwed to the other end of the output shaft 3b. One end surface 71 ′ of the preload adjusting nut 71 contacts the inner ring 27 a of the second ball bearing 27. A cap 73 covering the preload adjusting nut 71 and the lock nut 72.
Are fitted to the rack housing portion 6.

The inner ring 26 of the first ball bearing 26
a is prevented from being displaced in a direction away from the inner ring 27a of the second ball bearing 27, so that the inner ring 27a of the second ball bearing 27 is changed according to the amount of screwing of the preload adjusting nut 71 into the output shaft 3b. Can be pushed toward the inner race 26a of the first ball bearing 26. Outer rings 26b, 27 of both ball bearings 26, 27
b are restricted from being displaced toward each other as described above, and by screwing the preload adjusting nut 71 into the output shaft 3b, the two ball bearings 26, 2
7, a preload can be applied, thereby preventing the steering shaft 3 from rattling in the axial direction. The preload can be adjusted by adjusting the amount of screwing of the preload adjusting nut 71 into the output shaft 3b.

When assembling the steering device,
First, the input shaft 3a to which the first detection ring 36 and the third detection ring 38 are attached is connected to the worm wheel 1
0, the torque limiter mechanism 11, and the output shaft 3b to which the second detection ring 37 is attached.
Fit through 5. Next, the torsion bar 23
Is inserted into the input shaft 3a and the serration 2
4 to the output shaft 3b. The assembly including the input shaft 3a and the output shaft 3b is supported via the first ball bearing 26 by the gear housing 2 to which the worm 9 is attached. Thereby, the worm 9 and the worm wheel 10 can be engaged. Next, it is measured whether or not the backlash between the worm 9 and the worm wheel 10 is appropriate. If not, the worm 9 is disassembled and the worm wheel 10 is replaced. If the backlash is appropriate, the input shaft 3
The assembly including a, the output shaft 3b, and the gear housing part 2 is supported via the ball bearing 31 by the sensor housing 21 to which the first and second detection coils 33 and 34 are attached. The torque sensor 7 is configured by connecting the sensor housing 21 with bolts (not shown) and mounting the substrate 41. next,
When the steering wheel connected to the input shaft 3a is positioned in the straight steering state, the input shaft 3a is positioned relative to the output shaft 3b in the circumferential direction so that the output of the torque sensor 7 becomes zero. After the positioning, the pin 22 connects the torsion bar 23 to the input shaft 3a. Next, the assembly including the input shaft 3a, the output shaft 3b, the gear housing part 2, and the torque sensor 7 is supported by the rack housing part 6 covering the rack 5 via the second ball bearing 27, and the gear housing The part 2 and the rack housing part 6 are connected by bolts (not shown). Thereby, the pinion 4 and the rack 5 can be engaged. Next, the preload applied to the first ball bearing 26 and the second ball bearing 27 is adjusted by the preload adjusting nut 71 screwed to the output shaft 3b, and after the adjustment, the lock nut 72 is screwed to the output shaft 3b.
The cap 73 is attached to the rack housing 6. Then, by adjusting the amount of screwing of the plug 68 into the holding hole 65, the elasticity of the coil spring 69 pressing the rack 5 via the support yoke 66 is adjusted, and the meshing state between the rack 5 and the pinion 4 is optimized. . Thereafter, the lock nut 67 is screwed to the plug 68.

According to the above configuration, by applying an appropriate preload to the pair of ball bearings 26 and 27 that support the output shaft 3b, it is possible to prevent the output shaft 3b from rattling in the axial direction. Thereby, the fluctuation of the meshing state between the rack 5 and the pinion 4 can be prevented, and the steering feeling can be improved. Also, by preventing the output shaft 3b from rattling in the axial direction, the first detection ring 3 of the torque sensor 7 is prevented.
Variation in the distance between the second detection ring 37 and the second detection ring 37 can be prevented. Accordingly, it is possible to prevent the value of the steering torque detected based on the change in the magnetic resistance between the two detection rings 36 and 37 from fluctuating from an appropriate value, and to apply an appropriate steering assist force. Further, by simply adjusting the screwing amount of the preload adjusting nut 71, the preload can be easily and variably applied to the ball bearings 26 and 27. Before the gear housing 2 and the rack housing 6 are connected to each other, the worm 9 and the worm wheel 10 are engaged with the output shaft 3b supported by the gear housing 2 so that the worm 9 and the worm wheel It can be determined whether or not the backlash during 10 is appropriate. As a result, the worm wheel 1 for optimizing the backlash
0 can be replaced before the rack 5 is engaged with the pinion 4. Therefore, the disassembly and assembly work for optimizing the backlash can be simplified. In the above embodiment, the axial displacement of the worm wheel 10 is controlled by the inner race 26 of the first ball bearing 26 that supports the output shaft 3b.
Since it can be regulated by a, a dedicated displacement regulating member such as a retaining ring is not required. Thereby, the axial dimension of the output shaft 3b can be shortened, and downsizing can be achieved. further,
Since the preload applied to the ball bearings 26 and 27 can be adjusted as described above, it is possible to prevent the frictional force for preventing the relative slip between the inner ring 26a of the first ball bearing 26 and the worm wheel 10 from becoming excessive. This allows
The torque limiter mechanism 11 can function properly.

The present invention is not limited to the above embodiment. For example, the drive gear and the driven gear for transmitting the steering assist force are not limited to the worm and the worm wheel, but may be any gear.

[0034]

According to the present invention, a reduction in steering feeling can be easily prevented, an appropriate steering assist force can be applied, the assembling process can be simplified, the size can be reduced, and a proper fail-safe function can be achieved. And a rack-and-pinion type steering device that can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an electric power steering device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a circuit configuration of the torque sensor according to the embodiment of the present invention.

FIG. 3 is a sectional view of a main part of the electric power steering device according to the embodiment of the present invention;

FIG. 4 is a sectional view of a torque setting member in the torque limiter mechanism according to the embodiment of the present invention, and FIG.

FIG. 5 is a diagram illustrating a relationship between a radial deformation amount and a radial force of the torque setting member according to the embodiment of the present invention.

[Explanation of symbols]

 2 Gear housing part 2a, 6a Step surface (outer ring displacement prevention part) 3a Input shaft 3b Output shaft 3d Flange (inner ring displacement prevention part) 4 Pinion 5 Rack 6 Rack housing part 7 Torque sensor 8 Motor 10 Worm wheel 11 Torque limiter mechanism 26 First ball bearing 27 Second ball bearing 36 First detection ring 37 Second detection ring 71 Preload adjusting nut

Claims (5)

[Claims] 1. An output shaft for transmitting a steering torque, a pinion integrated with the output shaft so as to rotate together with the output shaft, a rack meshing with the pinion, a housing supporting the output shaft via a bearing, Means for applying a preload to the bearing in an adjustable manner. 2. An input shaft connected to the output shaft so as to be axially displaceable and elastically relatively rotatable in accordance with a steering torque, and a magnetic material member fixed to the input shaft and an output shaft. The method according to claim 1, further comprising: a torque sensor for detecting a steering torque based on a change in magnetic resistance between the fixed magnetic material member and a steering assisting force applying means corresponding to the detected steering torque. A rack and pinion type steering device as described in the above. 3. The output shaft is supported by the housing via a first rolling bearing and a second rolling bearing, and an outer ring displacement preventing portion for preventing the outer rings of the two rolling bearings from being displaced toward each other. An inner ring displacement preventing portion for preventing the inner ring of the first rolling bearing from being displaced away from the inner ring of the second rolling bearing; and a preload adjusting member screwed to the output shaft. The rack and pinion type steering device according to claim 1, wherein an inner ring of the second rolling bearing can be pushed toward an inner ring of the first rolling bearing according to an amount of screwing of the adjusting member into the output shaft. 4. A torque sensor for detecting the steering torque, an actuator for generating a steering assist force according to the detected steering torque, a drive gear rotated by the steering assist force, and meshed with the drive gear. And a driven gear fitted to the output shaft. The housing includes a gear housing portion that covers the drive gear and the driven gear, and a rack housing that is separate from the gear housing portion and covers the pinion and the rack. And the output shaft is supported by the gear housing portion via the first rolling bearing, whereby the driven gear can be meshed with the driven gear. The output shaft is formed by the gear housing portion. , The output shaft is moved by the rack housing through the second rolling bearing. The rack and pinion type steering apparatus according to claim 3, wherein the rack and pinion can be engaged with the pinion by supporting the gear housing and the rack housing with the gear housing. 5. A torque sensor for detecting the steering torque, an actuator for generating a steering assist force according to the detected steering torque, a drive gear rotated by the steering assist force, and meshed with the drive gear. And a driven gear fitted to the output shaft, and the driven gear is fitted via a torque limiter mechanism so that the driven shaft relatively rotates when a steering torque greater than a preset limit torque acts on the output shaft. The driven gear is disposed between an inner ring of the first rolling bearing and an inner ring displacement preventing portion, and the inner ring of the first rolling bearing is moved by the inner ring displacement preventing portion via the driven gear. 4. Displacement in a direction away from the inner ring of the second rolling bearing is prevented.
4. The rack and pinion type steering device according to 1.