JP2006205887A - Support structure for power steering assisting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid unnecessary driving of an electric motor even when reverse input is given from the wheel side as the steering wheel is rotated to the maximum in a power steering assisting device. <P>SOLUTION: This support structure for a power steering assisting device 10 is provided between an upper steering shaft 1 on the steering wheel side and a lower steering shaft 2 on the wheel side. A steering angle regulating means 200 to limit the maximum steering angle of the lower steering shaft 2 is provided between the lower steering shaft 2 and the vehicle body side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a support structure for an electric steering assist device.

  In rough terrain vehicles such as buggy vehicles, an electric steering assist device is interposed between the upper steering shaft on the steering handle side and the lower steering shaft on the wheel side, as described in Patent Document 1, and driving Some assist the steering force applied to the steering handle by the torque generated by the electric motor.

In the electric steering assist device of Patent Document 1, an input shaft to which the upper steering shaft is connected, an output shaft to which the lower steering shaft is connected, a torque sensor provided between the input shaft and the output shaft, A single unit in which a housing encloses an electric motor driven according to the detected torque, a worm gear coupled to the rotating shaft of the electric motor, and a worm wheel coupled to the output shaft and meshing with the worm gear. Built into the body, the housing can be attached to the body frame (vehicle body side bracket). When steering torque is applied to the steering handle, steering torque is also applied to the torsion bar connecting the input shaft and the output shaft via the upper steering shaft, and the torsion bar twists between the input shaft and the output shaft. To rotate relatively. As a result, the torque sensor detects the steering torque based on the displacement of the input shaft and the output shaft in the rotational direction, and the electric motor is controlled to apply an assist force corresponding to the steering torque to the output shaft.
JP2004-231011

In the conventional electric steering assist device provided on the rough terrain vehicle, when the steering wheel is steered to the maximum, if a reverse input continues from the wheel side due to a rock being caught on the wheel, the lower steering shaft and The output shaft continues to twist the torsion bar, and as a result, the torque sensor continues to detect the steering torque. For this reason, the electric motor continues to be driven despite the output shaft and the lower steering shaft reaching the end of the steering stroke, resulting in damage such as burning.
SUMMARY OF THE INVENTION An object of the present invention is to avoid driving of an electric motor even when a reverse input is input from the wheel side in a state where the steering handle is fully steered in an electric steering assist device.

  The invention according to claim 1 limits the maximum steering angle of the lower steering shaft in the support structure of the electric steering assist device interposed between the upper steering shaft on the steering handle side and the lower steering shaft on the wheel side. The steering angle restricting means is provided between the lower steering shaft and the vehicle body side.

  According to a second aspect of the present invention, in the first aspect of the invention, the steering angle restricting means further comprises a stopper portion provided on the vehicle body side and a stopper portion provided on the lower steering shaft, and the lower steering shaft is operated at maximum steering. When the corner is reached, the stopper portion of the lower steering shaft is stopped by the stopper portion on the vehicle body side.

(Claim 1)
(a) When the steering wheel is steered to the maximum and a reverse input is input from the wheel side, the steering angle restricting means limits the maximum steering angle of the lower steering shaft. Therefore, in the maximum steering angle state, the lower steering shaft and the output shaft do not continue to twist the torsion bar, and the torque sensor does not continue to detect the steering torque. The electric motor does not continue to drive after the output shaft and the lower steering shaft reach the steering stroke end.

(Claim 2)
(b) The steering angle restricting means can be simply configured by a stopper portion on the vehicle body side and a stoppered portion of the lower steering shaft.

  1 is a schematic diagram showing a support structure of an electric steering assist device, FIG. 2 is a sectional view taken along line II-II in FIG. 1, FIG. 3 is a sectional view taken along line III-III in FIG. FIG. 5 is a cross-sectional view showing the steering angle regulating means for the upper steering shaft along line IV-IV in FIG. 1, and FIG. 5 is a sectional view showing the steering angle regulating means for the lower steering shaft along line V-V in FIG.

  The electric steering assist device 10 is applied to rough terrain vehicles such as buggy cars and snowmobiles, for example. As shown in FIG. 1, an upper steering shaft 1 on the steering handle side and a lower steering shaft 2 on the wheel side are provided. The steering force is interposed between them and assists the steering force applied to the steering handle by the torque generated by the electric motor 24.

  The electric steering assist device 10 supports the upper steering shaft 1 on the upper vehicle body stay 3 so as to be rotatable via a bearing by a support member 4, and a steering handle mounting member 5 is fixed to an upper end portion. The lower steering shaft 2 is rotatably supported by a lower vehicle body stay 6 via a bearing by a support member 7, and a pitman arm 8 is fixed to an intermediate portion. The pitman arm 8 is connected to the front wheels via left and right tie rods. The upper vehicle body stay 3 and the lower vehicle body stay 6 are supported by the vehicle body frame.

  As shown in FIGS. 1 to 3, the electric steering assist device 10 includes a first housing (upper housing or upper cover) 11, a second housing (main body housing) 12, and a third housing (lower housing or lower cover) 13. The unit body 10A is configured to include an input shaft 21, an output shaft 22, a torque sensor 23, an electric motor 24, a worm gear 25, and a worm wheel 26.

  In the electric steering assist device 10, the upper end of the input shaft 21 to which the upper steering shaft 1 is connected by the connector 1A is supported by the first housing 11 by the bearing 31 (FIG. 2), and the lower steering shaft 2 is connected by the connector 2A. Are supported by the second housing 12 and the third housing 13 by upper and lower bearings 32A and 32B (FIG. 2). The input shaft 21 is provided with a serration 21A for connection with the connection tool 1A on the upper outer periphery, and the output shaft 22 is provided with a serration 22A for connection with the connection tool 2A on the lower outer periphery. A torsion bar 27 is inserted into the hollow portion of the input shaft 21, one end of the torsion bar 27 is connected to the input shaft 21 with a connecting pin 27 </ b> A, and the other end of the torsion bar 27 is inserted into the hollow portion of the output shaft 22. Serrated combined.

  When a steering torque is applied to the steering handle, the steering torque is also applied to the torsion bar 27 connecting the input shaft 21 and the output shaft 22 via the upper steering shaft 1, and the input shaft 21 and the output shaft 22 are torsioned. The bar 27 rotates relative to the twisted portion. Thereby, the torque sensor 23 detects the steering torque based on the displacement of the input shaft 21 and the output shaft 22 in the rotational direction, and the electric motor 24 is controlled to apply the assist force corresponding to the steering torque to the output shaft 22. become.

  As shown in FIG. 2, the torque sensor 23 includes two detection coils 23 </ b> A and 23 </ b> B surrounding the cylindrical core 23 </ b> C engaged with the input shaft 21 and the output shaft 22 in the first housing 11. The core 23 </ b> C includes a vertical groove 23 </ b> E that engages with the guide pin 23 </ b> D of the output shaft 22 and can move only in the axial direction, and includes a spiral groove 23 </ b> G that engages with the slider pin 23 </ b> F of the input shaft 21. As a result, a steering torque applied to the steering handle is applied to the input shaft 21, and when a relative displacement in the rotational direction occurs between the input shaft 21 and the output shaft 22 due to elastic torsional deformation of the torsion bar 27, the input shaft 21. The displacement in the rotational direction of the output shaft 22 causes the core 23C to be displaced in the axial direction, and the inductance of the detection coils 23A and 23B caused by the magnetic change around the detection coils 23A and 23B due to the displacement of the core 23C. Change. That is, when the core 23C moves toward the input shaft 21, the inductance of the detection coil 23A closer to the core 23C increases, and the inductance of the detection coil 23B farther away from the core 23C decreases. Torque can be detected.

  The electric motor 24 is mounted and supported on the second housing 12 by mounting bolts 28, and is driven by a controller (not shown) according to the torque detected by the torque sensor 23. A worm gear 25 is coupled to a rotating shaft 24A of the electric motor 24 by a joint 24B, and a worm wheel 26 that meshes with the worm gear 25 is fixed to the output shaft 22. As shown in FIG. 3, the worm gear 25 is supported on both ends of the second housing 12 by left and right bearings 41 and 42. The worm wheel 26 is fixed to the output shaft 22 directly below the upper bearing 32 </ b> A of the output shaft 22 inside the second housing 12.

  The joint 24B that couples the rotating shaft 24A of the electric motor 24 and the worm gear 25 is provided with a torque limiter 24C formed of an elastic ring in the fitting gap therebetween (FIG. 3). The torque limiter 24C continues to couple the rotating shaft 24A and the joint 24B with the normal use torque of the electric steering assist device 10, slips with the abnormal torque, and does not transmit the torque of the electric motor 24 to the joint 24B side.

  Therefore, in the electric steering assist device, the upper end portion of the input shaft 21 and the torque sensor 23 are supported on the first housing 11, and the upper end portion of the output shaft 22, the electric motor 24, and the worm gear 25 are supported on the second housing 12. The worm wheel 26 is supported, the lower end portion of the output shaft 22 is supported on the third housing 13, the first housing 11 and the second housing 12 are fastened by the mounting bolts 14, and the second housing 12 and the third housing 13 are attached. The unit unit 10A is formed by fastening with bolts 15 (FIG. 2). An oil seal 33 is sealed in the upper opening of the bearing 31 in the first housing 11, and an oil seal 34 is sealed in the lower opening of the bearing 32 </ b> B in the third housing 13 (FIG. 2).

  And the electric steering assistance apparatus 10 enables the 2nd housing 12 to be attached to the vehicle body side. As shown in FIGS. 1 and 2, the electric steering assist device 10 includes elastic members 51 such as rubber bushes on both sides of mounting bosses 12 </ b> A provided at a plurality of circumferential positions (for example, three positions) on the outer periphery of the second housing 12. 52, and between the upper and lower support pieces 18A, 18B of the bifurcated support portion 18 provided at a plurality of positions corresponding to the mounting boss 12A of the vehicle body side bracket 17, the mounting boss is interposed via the elastic members 51, 52. 12A is sandwiched. The upper and lower support pieces 18A, 18B are mounted by mounting bolts 16 (nuts 16A) inserted into bolt holes provided in the support pieces 18A, 18B, the elastic members 51, 52, and the mounting bosses 12A of the bifurcated support portion 18, respectively. The mounting boss 12A is held in a floating fixed state via the elastic members 51 and 52. The vehicle body side bracket 17 is supported by the vehicle body frame.

  However, in the electric steering assist device 10, (A) the first steering angle restricting means 100 for avoiding the actuating drive of the electric motor 24 in the state where the steering handle is fully steered; B) The second steering angle restricting means 200 is provided as follows for avoiding the need to drive the electric motor 24 even when a reverse input is input from the wheel side with the steering handle fully steered.

(A) First steering angle regulating means 100 (FIGS. 1 and 4)
The first steering angle restricting means 100 is provided between the upper steering shaft 1 and the vehicle body side, and restricts the maximum steering angle of the upper steering shaft 1.

  As shown in FIGS. 1 and 4, the first steering angle restricting means 100 includes both left and right side portions of the opening 4 </ b> B in which the annular wall 4 </ b> A of the annular support member 4 provided in the upper vehicle body stay 3 is partially cut in the circumferential direction. Are the left and right stopper portions 101A and 101B, and the protrusions provided on the outer periphery of the upper steering shaft 1 and between the left and right stopper portions 101A and 101B of the opening 4B are the stopper portions 102. The opening 4B is provided so as to face the front or back of the annular wall 4A facing the front of the vehicle, for example. When the steering handle is in the neutral position, the stopper portion 102 of the upper steering shaft 1 is in the center in the rotation direction with respect to the left and right stopper portions 101A and 101B of the support member 4, and between the stopper portion 102 and the stopper portion 101A. The left steering angle θ1 is interposed between the stopper portion 102 and the stopper portion 101B, and the right steering angle θ2 is interposed (θ1 = θ2). When the steering handle and the input shaft 1 reach the left or right maximum steering angle θ1M, θ2M (θ1M = θ2M), the stopper portion 102 of the upper steering shaft 1 is moved to the left or right stopper portion 101A of the support member 4. , 101B to stop and stop. θ1M = θ1 and θ2M = θ2.

According to the present embodiment, the following operational effects can be obtained.
(a) When the steering handle is steered to the maximum, the maximum steering angle of the upper steering shaft 1 connected to the steering handle is limited by the first steering angle restricting means 100. Accordingly, in the maximum steering state, the upper steering shaft 1 and the input shaft 21 do not continue to twist the torsion bar 27, and the torque sensor 23 does not continue to detect the steering torque. The electric motor 24 is not continuously driven after the output shaft 22 and the lower steering shaft 2 reach the end of the steering stroke.

  (b) The first steering angle regulating means 100 can be simply configured by the body-side stopper portions 101A and 101B and the stoppered portion 102 of the upper steering shaft 1.

(B) Second steering angle regulating means 200 (FIGS. 1 and 5)
The second steering angle restricting means 200 is provided between the lower steering shaft 2 and the vehicle body side, and restricts the maximum steering angle of the lower steering shaft 2.

  As shown in FIGS. 1 and 5, the second steering angle restricting means 200 is provided with the support member 7 on the lower vehicle body stay 6, for example, the front (or rear) vehicle body stay 6 facing the front of the vehicle. Left and right stopper portions 201A and 201B are provided, and a C-shaped stoppered portion 202 is provided on the outer periphery of the lower steering shaft 2 and between the left and right stopper portions 201A and 201B. The stopper portion 202 includes plate-like pieces 202A and 202B that are welded to the left and right two positions on the outer periphery of the lower steering shaft 2 and have a C-shape.

  When the steering handle is in the neutral position, the stopper portion 202 of the lower steering shaft 2 is in the center of the rotation direction with respect to the left and right stopper portions 201A and 201B of the vehicle body side stay 6, and the stopper portion 202 and the stopper portion 201A A left steering angle θ1A is interposed therebetween, and a right steering angle θ2A is interposed between the stopper portion 202 and the stopper portion 201B (θ1A = θ2A). When the lower steering shaft 2 reaches the maximum steering angles θ1M and θ2M (θ1M = θ2M) together with the upper steering shaft 1 by the operation applied to the steering handle and the input shaft 1, the stopper portion 202 of the lower steering shaft 2 is moved. The left or right stopper portions 201A, 201B of the vehicle body side stay 6 are brought into close contact with each other or stopped. θ1M = θ1A and θ2M = θ2A.

  In the present embodiment, the first steering angle restricting means 100 on the upper steering shaft 1 side and the second steering angle restricting means 200 on the lower steering shaft 2 side are provided side by side. When the input shaft 1 is rotated to the maximum steering angle position, and the lower steering shaft 2 is set to the maximum steering angle position, the stopper portion 102 of the first steering angle restricting means 100 is placed before the stopper portions 101A and 101B. It is preferable that the stoppered portion 202 of the second steering angle restricting means 200 abuts with the stopper portions 201A and 201B (θ1 <θ1A, θ2 <θ2A).

According to the present embodiment, the following operational effects can be obtained.
(a) When the steering wheel is steered to the maximum and a reverse input is input from the wheel side, the second steering angle restricting means 200 limits the maximum steering angle of the lower steering shaft 2. Therefore, in the maximum steering angle state, the lower steering shaft 2 and the input shaft 22 do not continue to twist the torsion bar 27, and the torque sensor 23 does not continue to detect the steering torque. The electric motor 24 is not continuously driven after the output shaft 22 and the lower steering shaft 2 reach the end of the steering stroke.

  (b) The second steering angle restricting means 200 can be simply configured by the vehicle body side stopper portions 201A and 201B and the stoppered portion 202 of the lower steering shaft 2.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention. In the present invention, the gear train that transmits the rotation of the electric motor to the output shaft is not limited to a worm gear and a worm wheel.

FIG. 1 is a schematic diagram showing a support structure of an electric steering assist device. FIG. 2 is a sectional view taken along line II-II in FIG. FIG. 3 is a sectional view taken along line III-III in FIG. FIG. 4 is a cross-sectional view showing the steering angle regulating means for the upper steering shaft along the line IV-IV in FIG. FIG. 5 is a cross-sectional view showing the steering angle regulating means for the lower steering shaft along the line V-V in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper steering shaft 2 Lower steering shaft 10 Electric steering assist device 200 Steering angle restricting means 201A, 201B Stopper portion 202 Stopped portion

Claims (2)

In the support structure of the electric steering assisting device interposed between the upper steering shaft on the steering handle side and the lower steering shaft on the wheel side,
A support structure for an electric steering assist device, characterized in that a steering angle restricting means for limiting the maximum steering angle of the lower steering shaft is provided between the lower steering shaft and the vehicle body side.   The steering angle restricting means comprises a stopper portion provided on the vehicle body side and a stopper portion provided on the lower steering shaft. When the lower steering shaft reaches the maximum steering angle, the stopper portion of the lower steering shaft is The support structure for the electric steering assist device according to claim 1, wherein the electric steering assist device is stopped by a stopper on the vehicle body side.

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