JPH09323661A - Vehicle steering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve power assist according to a steering torque by decreasing a change in a meshing condition between a rack and opinion to secure a predetermined rigidity. SOLUTION: A vehicle steering apparatus 10 comprises: a pinion shaft 12 meshed with a rack shaft supported by a support beam 200 in a cantilever support. The support beam 200 has an flexibility and thereby a displacement of the pinion shaft 12 together with the support beams 200 along an axial direction of a rack shaft 24 is possible. Therefore, when steering, the pinion shaft 12 can be displaced along the axial direction of the rack shaft 24 according to a steering torque together with the support beam 200 and a change in a meshed condition between a rack and a pinion is alleviated, so that a predetermined rigidity can be secured. Power assist can be realized in accordance with the steering torque by detecting a displacement of the pinion shaft 12 (support beam 200).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering apparatus in which a pinion shaft connected to a steering wheel is connected to a rack shaft for turning steered wheels.

[0002]

2. Description of the Related Art In a vehicle steering system in which a pinion shaft connected to a steering wheel is connected to a rack shaft for steering steered wheels, a power assist based on an input torque of the pinion shaft is performed to rotate the pinion shaft. A steering device (power steering device) configured to steer a steering wheel is known (for example, Japanese Patent Laid-Open No. 167869/1982).

In the steering device disclosed in the above publication, the pinion shaft meshing with the rack shaft is swingably supported.
It swings according to the steering torque. Further, a hydraulic control valve is connected to the pinion shaft, and the hydraulic control valve is operated by the swing of the pinion shaft. As a result, the hydraulic pressure is controlled according to the steering torque and predetermined power assist is performed.

However, in the conventional steering device disclosed in the above publication, since the pinion shaft is configured to swing around the fulcrum and displace with respect to the rack shaft, the pinion shaft is displaced due to the displacement of the pinion shaft. And the meshing condition of the teeth of the rack shaft changes. That is, the rack and pinion meshing is displaced in a direction away from each other, and the meshing rigidity is lowered, and the rigidity is lowered, and the operation accuracy is also lowered.

[0005]

SUMMARY OF THE INVENTION In consideration of the above facts, the present invention can reduce the change in the meshing state of the teeth of the pinion shaft and the rack shaft to secure a predetermined rigidity, and can respond to the steering torque. It becomes possible to perform power assist,
In addition, it is an object of the present invention to obtain a vehicle steering system that can suppress transmission of an excessive reverse input to the pinion shaft.

[0006]

According to a first aspect of the present invention, there is provided a vehicle steering system in which a pinion shaft connected to a steering wheel is connected to a rack shaft for steering steered wheels. In the picking device, one end is attached to the housing, and the other end rotatably supports the pinion shaft and also supports the pinion shaft so as to be displaceable along the rack shaft according to the magnitude of steering torque. It is characterized by having a member.

In the vehicle steering apparatus according to the first aspect, when the pinion shaft is steered via the steering wheel,
This steering force is transmitted via the rack shaft, and the steered wheels are steered.

Immediately after steering, since the resistance of the rack shaft (that is, the steered wheel side) is large, the rack shaft is immovable, and therefore the pinion shaft is displaced along the rack shaft via the support member. In this case, the pinion shaft is not configured to simply swing around the fulcrum to be displaced with respect to the rack shaft, but is supported by the support member so as to be displaceable along the rack shaft. Therefore, even if the pinion shaft is displaced. Changes in the meshing state of the teeth of the pinion shaft and the rack shaft are reduced. That is, a predetermined rigidity can be secured without the engagement rigidity of the rack and pinion being displaced in the direction away from each other and the engagement rigidity being lowered, so that the operation accuracy is not lowered due to the rigidity reduction.

A vehicle steering system according to a second aspect of the invention is
The vehicle steering apparatus according to claim 1, further comprising a displacement detection unit that detects a displacement of the support member in the rack axial direction, and power assist is performed based on a detection result of the displacement detection unit. .

In the vehicle steering apparatus according to the second aspect, the displacement of the support member in the rack axis direction is detected by the displacement detecting means, and the power assist is performed based on the detection result.

Here, the displacement of the support member in the rack axis direction corresponds to the magnitude of the steering torque from the pinion shaft. Therefore, the steering torque can be detected by detecting the displacement of the support member in the rack axis direction by the displacement detecting means, and the power assist based on the steering torque can be performed. it can.

A vehicle steering system according to a third aspect of the invention is
The vehicle steering apparatus according to claim 1 or 2, wherein the support member displaceably supports the pinion shaft along an axial direction of the pinion shaft, and supports the pinion shaft when the pinion shaft is displaced in the axial direction. It is characterized in that a friction damping portion is provided which abuts and attenuates the rotation of the pinion shaft by a frictional force.

In the vehicle steering apparatus according to the third aspect, the pinion shaft is not only displaceable along the rack shaft but also displaceable along its own axial direction. Therefore,
For example, when a reverse input is transmitted from the steered wheels via the rack shaft due to a curb collision, etc., the component force of this reverse input causes the pinion shaft to displace along its own axial direction, causing friction. The damping portion contacts the pinion shaft. Thus, the rotation of the pinion shaft is attenuated by the frictional force, an excessive reverse input is suppressed from being transmitted to the pinion shaft (that is, the steering wheel), and kickback is reduced.

[0014]

1 to 5 are schematic sectional views showing the overall construction of a vehicle steering system 10 according to a first embodiment of the present invention.

The vehicle steering system 10 is applied, for example, as an electric power steering system for a vehicle.
A pinion shaft (steering shaft) 12 is provided. Pinion shaft 1
2, a steering wheel (not shown) is attached, and is arranged in a direction substantially orthogonal to the rack shaft 24,
The housing 19 is supported by the support beam 200 as a support member.
It is supported by 4. The support beam 200 has four legs 201.
Each of the leg portions 201 has a tip end fixed to the housing 194. The pinion shaft 12 is rotatably supported by bearings 203 and 205 on the top of the support beam 200. That is, the pinion shaft 12 is cantilevered by the support beam 200. A pinion 196 is provided on the pinion shaft 12 and meshes with the rack gear 198 of the rack shaft 24.

Here, the support beam 200 that rotatably supports the pinion shaft 12 has flexibility along the axial direction of the rack shaft 24. Therefore, the pinion shaft 12 has the axial line of the rack shaft 24. It can be displaced along the direction.

One end of a lever 202 is connected to the top of the support beam 200 (in the vicinity of the bearing 203). Therefore, when the pinion shaft 12 is displaced along with the support beam 200 along the rack shaft 24, the lever 202 is moved along the longitudinal direction.

The vehicle steering system 10 further includes a motor section 34. The motor unit 34 is a so-called print motor, and includes an armature 36, a first magnetic pole piece 38 and a second magnetic pole piece 4 which are provided on both sides of the armature 36 so as to face each other.
0. A motor rotation shaft 42 is fixed to the center of the armature 36, and the motor rotation shaft 42 is rotatably supported by the housing 16. Armature 3
The motor rotation shaft 42 of No. 6 is provided with a gear 204, and is further connected to a rack gear 210 of the rack shaft 24 via a reduction gear 206 and a pinion 208.

On the other hand, the first magnetic pole piece 38 and the second magnetic pole piece 40 are fixed to the housing 16 so as to face both sides of the armature 36.

A limit switch 214 is integrally provided on the motor section 34. As shown in FIG. 5, the limit switch 214 is the lever 202 described above.
By operating the contact 216 connected to the right and left to contact the fixed contacts 217 and 219 respectively, it is possible to detect the steering state of the pinion shaft 12 (right / left switching state). The limit switch 214 is connected to the brush 76 and the brush 78 of the motor unit 34, and can switch the energization direction to the motor unit 34 (armature 36) according to the steering direction of the pinion shaft 12.

Further, a displacement sensor 207 as a displacement detecting means is arranged corresponding to the intermediate portion of the lever 202. When the displacement sensor 207 engages with the lever 202, the displacement amount of the lever 202, that is, the support beam 20.
A displacement of 0 (pinion shaft 12) can be detected.
The displacement sensor 207 is connected to the ECU 209. The ECU 209, based on the displacement amount of the support beam 200 (pinion shaft 12) detected by the displacement sensor 207,
Limit switch 214 (brush 76 of the motor unit 34,
It controls the value of the current supplied to the brush 78).

Next, the operation of the first embodiment will be described. In the vehicle steering apparatus 10 having the above-described configuration, when the steering wheel (pinion shaft 12) is not steered (vehicle straight ahead state), as shown in FIG.
The operation contact 216 of 14 does not move, the limit switch 214 is turned off, and the motor section 34 is not energized.

Steering wheel (pinion shaft 12)
When is steered, the motor unit 34 is operated according to the steering torque.

That is, when the pinion shaft 12 is steered to the left or right, the steering force of the pinion shaft 12 is passed through the pinion 196 and the rack gear 198 when turning to the right as shown by arrow A in FIG. When transmitted to the rack shaft 24, the rack shaft 24 is driven in the axial direction (arrow D direction) and the steered wheels are steered.

In this case, immediately after the steering of the pinion shaft 12, the rack shaft 24 is immovable because the resistance of the rack shaft 24 (that is, the tire side) is large. Therefore, the pinion shaft 12 and the support beam 200 together with the rack shaft 24. Displaced slightly along. Therefore, the lever 202 is moved along the longitudinal direction by the displacement of the pinion shaft 12. As the lever 202 moves, the displacement sensor 207 moves the lever 2
02 movement amount, that is, support beam 200 (pinion shaft 12)
Is detected, and the ECU 20 is detected based on the detection result.
9 controls the value of the current supplied to the limit switch 214. Furthermore, the movement of the lever 202 causes the movement of FIG.
As shown in FIG.
Moves, the limit switch 214 is turned on, the motor section 34 (armature 36) is energized, and the armature 36 of the motor section 34 rotates.

As a result, the driving force of the motor section 34 acts on the rack shaft 24 to which the motor rotating shaft 42 is connected, and is applied as an auxiliary driving force. Therefore, the pinion shaft 12
The steering force of the (steering wheel) is reduced.

On the other hand, when the pinion shaft 12 is steered to the left (direction of arrow C in FIG. 1), the steering force of the pinion shaft 12 is applied to the rack shaft 2 via the pinion 196 and the rack gear 198.
4 to drive the rack shaft 24 in the axial direction (direction of arrow B) to steer the steered wheels.

Also in this case, immediately after the steering of the pinion shaft 12, the rack shaft 24 is immovable because the resistance of the rack shaft 24 (that is, the tire side) is large. There is a slight displacement along the axis 24. Therefore, the lever 202 is moved along the longitudinal direction by the displacement of the pinion shaft 12. With the movement of the lever 202, the displacement sensor 207 causes the movement amount of the lever 202, that is, the support beam 200 (the pinion shaft 1).
2) The displacement is detected, and based on the detection result, the ECU
209 controls the value of the current supplied to the limit switch 214. Further, by moving the lever 202, the
As shown in (A), as the lever 202 moves, the operating contact 216 of the limit switch 214 moves in the opposite direction to the one described above, the limit switch 214 turns on, and the motor unit 3
4 (armature 36) is energized and the armature 3 of the motor unit 34
6 rotates in the opposite direction to the above.

As a result, the driving force of the motor section 34 acts on the rack shaft 24 to which the motor rotating shaft 42 is connected, and is applied as an auxiliary driving force. Therefore, the pinion shaft 12
The steering force of the (steering wheel) is reduced.

In this case, the displacement amount of the lever 202 detected by the displacement sensor 207, that is, the displacement amount of the support beam 200 supporting the pinion shaft 12 corresponds to the magnitude of the steering torque from the pinion shaft 12, The detection value of the sensor 207 is changed according to the magnitude of the steering torque. Therefore, the driving force of the motor unit 34 increases or decreases according to the steering torque, and power assist is performed based on the steering torque from the pinion shaft 12 as in the case of the conventional hydraulic power steering apparatus, and a predetermined value is obtained. Output torque can be applied to the rack shaft 24.

When the steering wheel (pinion shaft 12) is switched to the left or right, the energization direction of the motor section 34 to the armature 36 is switched by the operation of the lever 202 and the limit switch 214 as described above.
The rotation direction of the motor rotation shaft 42 is switched to correspond to the steering direction of the pinion shaft 12.

Furthermore, in the vehicle steering system 10, when the pinion shaft 12 is displaced along the rack shaft 24 via the support beam 200 (during steering steering), the pinion shaft 12 simply swings around the fulcrum. Move the rack shaft 24
Since it is supported by the support beam 200 so as to be displaceable along the rack shaft 24, instead of being displaced with respect to
Even if the pinion shaft 12 is displaced, changes in the meshing state of the teeth of the pinion 196 of the pinion shaft 12 and the rack gear 198 of the rack shaft 24 are reduced. That is, the pinion 19
The predetermined rigidity can be ensured without the engagement rigidity of 6 and the rack gear 198 being displaced in the direction away from each other and the engagement rigidity being lowered. Therefore, the operation accuracy does not decrease due to the decrease in rigidity.

As described above, in the vehicle steering system 10 according to the first embodiment, the pinion shaft 12 is attached to the support beam 200.
Since it is supported so as to be displaceable along the rack shaft 24, the meshing rigidity of the pinion 196 and the rack gear 198 can be secured. Furthermore, the pinion shaft 12
The displacement sensor 207 detects the displacement of the (support beam 200), and the drive control of the motor unit 34 is performed according to the steering torque, so that the steering force can be favorably assisted. Further, the structure is simple, and the cost and the size and weight can be significantly reduced.

If a strain gauge is attached to the support beam 200 instead of the displacement sensor 207, the steering torque can be detected with high sensitivity and accuracy, and a phenomenon such as flutter in a relatively high frequency range can be detected. Can be detected. Further, by appropriately adjusting the rigidity of the support beam 200, the rack guide or the like for supporting the rack shaft 24 may be omitted.

Next, another embodiment of the present invention will be described. The same components as those in the first embodiment are basically assigned the same reference numerals as those in the first embodiment, and the description thereof will be omitted.

6 to 8 are schematic sectional views showing the overall structure of a vehicle steering system 220 according to a second embodiment of the present invention.

This vehicle steering system 220 has the same structure as the pinion shaft 12 and the support beam 200 as the above-described vehicle steering system 10, and further has a hydraulic control valve 222 in place of the motor section 34. Has been. This hydraulic control valve 22
2 is connected to the pump 224, and the rack shaft 24
It is connected to the left and right cylinder chambers 226 and 228 provided in, and can adjust and supply the oil liquid to each cylinder chamber 226 and 228. In addition, the spool 22 of the hydraulic control valve 222
3 is connected to the lever 202 described above, and is configured to be actuated by the displacement of the pinion shaft 12 (support beam 200).

In this vehicle steering system 220, when the steering wheel (pinion shaft 12) is steered, the pinion shaft 12 is displaced along with the support beam 200 along the rack shaft 24 in accordance with the steering torque as described above. To do. Therefore, the lever 202 is moved along the longitudinal direction by the displacement of the pinion shaft 12. With the movement of the lever 202, the hydraulic control valve 222 is actuated, and the left and right cylinder chambers 2
The oil liquid is adjusted and sent to 26 and 228. As a result, the auxiliary drive force is applied to the rack shaft 24, and the steering force of the pinion shaft 12 (steering wheel) is reduced.

In this case, the operation amount of the hydraulic control valve 222 by the lever 202, that is, the displacement amount of the support beam 200 supporting the pinion shaft 12 corresponds to the magnitude of the steering torque from the pinion shaft 12, and the hydraulic control is performed. The operation amount of the valve 222 is changed according to the magnitude of the steering torque. Therefore, the hydraulic pressure applied to the cylinder chambers 226 and 228 increases or decreases according to the steering torque, and power assist based on the steering torque from the pinion shaft 12 is performed as in the conventional hydraulic power steering apparatus. A predetermined output torque can be applied to the rack shaft 24.

Further, also in this vehicle steering system 220, the pinion shaft 12 is supported by the support beam 200 so as to be displaceable along the rack shaft 24, as in the first embodiment described above. , The pinion 196 of the pinion shaft 12 and the rack shaft 24 even if the pinion shaft 12 is displaced.
The change in the meshing state of the teeth with the rack gear 198 is reduced. That is, the pinion 196 and the rack gear 198.
The predetermined rigidity can be ensured without the engagement rigidity being displaced in the direction in which it disengages and the engagement rigidity being reduced.
Therefore, the operation accuracy does not decrease due to the decrease in rigidity.

As described above, in the vehicle steering system 220 according to the second embodiment, the pinion shaft 12 is attached to the support beam 20.
Since it is supported by 0 so that it can be displaced along the rack shaft 24, the meshing rigidity of the pinion 196 and the rack gear 198 can be secured. Furthermore, pinion shaft 1
The hydraulic control valve 222 is operated by the displacement of 2 (support beam 200) to perform hydraulic control according to the steering torque.
It is possible to favorably assist the steering force. Further, the structure is simple, and the cost and the size and weight can be significantly reduced.

9 to 10 are schematic sectional views showing the overall construction of a vehicle steering system 230 according to a third embodiment of the present invention.

The vehicle steering device 230 includes the motor section 34 of the vehicle steering device 10 and the vehicle steering device 22 described above.
It is configured as a manual steering device in which the zero hydraulic control valve 222 is omitted. The configurations of the pinion shaft 12, the support beam 200, and the like are the same as those of the vehicle steering devices 10 and 22 described above.
Basically the same as 0, but the leg 201 of the support beam 200
Has a thin intermediate portion as shown in FIG.
Thus, the pinion shaft 12 is supported so as to be displaceable even in the axial direction.

A friction damping portion 232 is provided on the housing 194 facing the tip of the pinion shaft 12. A slight clearance is provided between the friction damping portion 232 and the pinion shaft 12, and the pinion shaft 12 is normally separated from the friction damping portion 232. Further, the housing 194 facing the inner race 203A of the bearing 203 supporting the pinion shaft 12 is provided with a friction damping portion 234. A slight clearance is provided between the friction damping portion 234 and the inner race 203A of the bearing 203, and the inner race 203A is normally separated from the friction damping portion 234.

In this vehicle steering system 230, when the steering wheel (pinion shaft 12) is steered, the steering force of the pinion shaft 12 is changed by the pinion 196 and the rack gear 1.
It is transmitted to the rack shaft 24 via 98, and the rack shaft 24
Is driven in the axial direction to steer the steered wheels.

Here, in this vehicle steering system 230,
The pinion shaft 12 (support beam 200) can be displaced not only along the rack shaft 24, but also along its own axial direction. Therefore, when a reverse input is transmitted from the steered wheel side through the rack shaft 24 due to, for example, a curb collision, the pinion shaft 1 is caused by the component force of the reverse input.
2 is displaced along its own axial direction, and the tip end portion of the pinion shaft 12 and the friction damping portion 232 or the inner race 203A of the bearing 203 and the friction damping portion 234 come into contact with each other.
As a result, the friction force between the two causes the pinion shaft 12
Is dampened, the excessive reverse input is suppressed from being transmitted to the pinion shaft 12 (that is, the steering wheel), and kickback is reduced.

As described above, in the vehicle steering system 230 according to the third embodiment, not only the meshing rigidity of the pinion 196 and the rack gear 198 can be ensured, but also an excessive reverse input can prevent an excessive reverse input. Can be suppressed from being transmitted to.

In the third embodiment,
Although an example in which the vehicle steering device 230 is configured as a so-called manual steering device and the friction damping portion 232 and the friction damping portion 234 are provided in the vehicle steering device 230 has been described, the invention is not limited to this, and the vehicle steering device 10 described above may be used. Such as an electric power steering device or a hydraulic power steering device such as the vehicle steering device 220.
Of course, it is also possible to apply the friction damping portion 234.

[0049]

As described above, in the vehicle steering system according to the first aspect, it is possible to reduce the change in the meshing state of the teeth of the pinion shaft and the rack shaft and to secure a predetermined rigidity. The operation accuracy does not decrease due to the decrease, and the vehicle steering apparatus according to the second aspect has an excellent effect that the power assist can be performed according to the steering torque. Furthermore, the vehicle steering apparatus according to the third aspect has an excellent effect that it is possible to suppress transmission of an excessive reverse input to the pinion shaft.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a vehicle steering system according to a first embodiment of the present invention as viewed from the front side.

FIG. 2 is a sectional view showing the configuration of the vehicle steering system according to the first embodiment of the present invention, as viewed from the back side.

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 1, showing the configuration of the vehicle steering system according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 1 showing the configuration of the vehicle steering system according to the first embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing an operating state of a limit switch of the vehicle steering system according to the first embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a configuration of a vehicle steering system according to a second embodiment of the present invention, as viewed from the front side.

FIG. 7 is a cross-sectional view showing a configuration of a vehicle steering system according to a second embodiment of the present invention, as viewed from the back side.

FIG. 8 is a cross-sectional view taken along line 8-8 of FIG. 6 showing a configuration of a vehicle steering system according to a second embodiment of the present invention.

FIG. 9 is a sectional view showing a configuration of a vehicle steering system according to a third embodiment of the present invention, as viewed from the front side.

FIG. 10 is a cross-sectional view taken along the line 10-10 in FIG. 9 showing the configuration of the friction damping portion of the vehicle steering system according to the third embodiment of the invention.

[Explanation of symbols]

 10 Vehicle Steering Device 12 Pinion Shaft 24 Rack Shaft 34 Motor Section 194 Housing 202 Lever 214 Limit Switch 200 Support Beam (Supporting Member) 201 Leg 207 Displacement Sensor (Displacement Detection Means) 220 Vehicle Steering Device 222 Hydraulic Control Valve 230 Vehicle Steering Device 232 Friction Damping Section 234 Friction Damping Section

Claims (3)

[Claims] 1. A steering apparatus for a vehicle, wherein a pinion shaft connected to a steering wheel is connected to a rack shaft for steering steered wheels, wherein one end is attached to a housing and the other end is the pinion. A steering device for a vehicle, comprising: a support member that rotatably supports a shaft and also supports the pinion shaft so that the pinion shaft can be displaced along the rack shaft according to a magnitude of a steering torque. 2. The vehicle according to claim 1, further comprising displacement detecting means for detecting displacement of the support member in the rack axis direction, and performing power assist based on a detection result of the displacement detecting means. Steering device. 3. The support member supports the pinion shaft so as to be displaceable along the axial direction thereof, and contacts the pinion shaft when the pinion shaft is displaced in the axial direction to rotate the pinion shaft by a frictional force. A friction damping portion for damping the friction is provided.
The vehicle steering device described.