JPH10119796A - Motor-driven power steering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To connect an input shaft and a torsion bar by a pin in the correct position relation without dislocation of relative position relation between the input shaft and torsion bar caused by vibration or the like generated at the time of machining a pinhole or pressing in the pin and without the anxiety of dislocation of a neutral point or the like of a steering torque detecting means. SOLUTION: A steering torque detecting means for detecting a relative angle of torsion between an input shaft and an output shaft is provided between the input shaft and the output shaft with a torsion bar interposed, and auxiliary torque is generated on the basis of information of the steering torque detecting means. In a motor-driven power steering of such constitution, a constricted part 31b is provided near the tip of the input shaft 31, and this constricted part 31b is provided with nearly parallel clamping faces 31c, 31c for clamping. The torsion bar is connected to the tip part side from the clamping faces 31c, 31c by a pin 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement in an electric power steering device mounted on a vehicle.

[0002]

2. Description of the Related Art In recent years, electric power steering devices have been frequently used in order to reduce the steering force of a steering wheel to provide a comfortable steering feeling. This type of electric power steering apparatus generates an auxiliary torque according to a steering torque by an electric motor and transmits the auxiliary torque to a steering system via a mechanical clutch. Technology for Compensating Temperature Characteristics of Sensor ". In this technique, according to FIG. 1 of the publication, the input shaft 6 and the output shaft 7 are connected via a torsion bar 8 (the numbers are cited in the publication. The same applies hereinafter). The steering torque sensor 1 detects the relative torsion angle between the output shafts 6 and 7 by the steering torque detecting means including the detection coils 2a and 2b and the core 4. Such a steering torque sensor 1 generally adjusts the neutral position of the steering torque detecting means after assembly, and pin-connects the input shaft 6 and the torsion bar 8 at the adjusted position. The joining method will be described below.

FIG. 12 is a diagram for explaining a method of connecting a pin of an input shaft and a torsion bar of a general electric power steering apparatus. The reference numerals have been re-assigned. As the pin connection procedure, first, the subassembly 1 of the electric power steering device is used.
And the input shaft 103, the output shaft 104, and the torsion bar 105 are respectively fixed to the input shaft fixing jig 106, the output shaft fixing jig 107, and the torsion bar fixing jig 108. Fixed to. Next, the neutral position of the steering torque detecting means 109 is adjusted. Then, at the adjusted position, the input shaft 103 and the torsion bar 105 are
The input shaft 103 and the torsion bar 105 are connected by press-fitting the pin 113 into the pin hole.

[0004]

However, FIG.
In the pin connection method 2, the input shaft 103 which is a large-diameter cylinder
Is very slippery, an extremely large pressing force must be applied to clamp with the input shaft fixing jig 106.
If the pressing force is too large, the input shaft 103, which is a hollow cylinder, may be elliptical, which is inconvenient. Further, if the pressing force is insufficient, there is a concern that the neutral point of the steering torque detecting means 109 may be shifted due to the vibration generated during the processing of the pin hole.

[0005] Further, since the position of the pin hole is relatively close to the steering torque detecting means 109, there is a concern that the neutral point of the steering torque detecting means 109 may be displaced by vibration during the processing of the pin hole.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a technique capable of accurately pin-connecting the neutral point of the steering torque detecting means when the input shaft and the torsion bar are pin-connected. is there.

[0007]

In order to achieve the above object, the invention according to claim 1 is directed to a method of forming a relative torsion angle between an input shaft and an output shaft between an input shaft and an output shaft via a torsion bar. In an electric power steering device for providing an auxiliary torque based on information of the steering torque detecting means, a constricted portion is provided near a tip of the input shaft, and the constricted portion is provided for clamping. Are provided, and the torsion bar is connected to a tip portion of the clamp surface with a pin.

The input shaft can be easily and securely clamped by clamping the clamp surfaces of the constricted portion that are substantially parallel to each other. Therefore, when the input shaft and the torsion bar are connected to each other with a pin, the relative positional relationship between the input shaft and the torsion bar does not deviate due to vibration generated at the time of pin hole processing or pin press-fitting. Therefore, since the input shaft and the torsion bar can be pin-coupled with an accurate positional relationship, there is no fear that the neutral point or the like of the steering torque detecting means is shifted. In addition, since the input shaft and the torsion bar are pin-connected at the tip of the clamp surface to be clamped, there is no concern that the neutral point of the steering torque detecting means may shift due to vibrations generated during pin hole processing or pin press-fitting. Absent. As described above, since the neutral point or the like of the steering torque detecting means does not shift, the input shaft and the torsion bar can be accurately pin-coupled.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference numerals. FIG. 1 is a system diagram of an electric power steering device according to the present invention. The electric power steering device 1 includes a rack and pinion mechanism 3 (including a pinion 4 and a rack shaft 5) connected to a steering handle 2, and steering. A steering torque detecting means 6 for detecting a steering torque of the steering system generated by the steering wheel 2, a control means 7 for generating a control signal based on a detection signal of the steering torque detecting means 6, and a control signal of the control means 7 And a ball screw 9 for transmitting the auxiliary torque of the electric motor 8 to the rack shaft 5.
Tie rods 11, 11 and knuckle arms 12, 1
This is a device that steers wheels (steered wheels) 13 through the wheel 2.

FIG. 2 is an overall configuration diagram of an electric power steering apparatus according to the present invention. The electric power steering apparatus 1 includes a rack and pinion mechanism 3 shown in FIG.
The motor 8 and the ball screw 9 are housed in a steering gear box 21 extending in the vehicle width direction, and an input shaft 31 is connected via a universal joint 23 to a steering shaft 22 connected to the steering handle 2.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2. The electric power steering apparatus 1 has a tubular input shaft 31 connected to the steering shaft (see FIG. 2), and penetrates through the input shaft 31. A torsion bar 33 having an upper portion pin-connected to the input shaft 31 and an output shaft 34 having a serration coupled to a lower portion of the torsion bar 33 and having the pinion 4 provided at a lower portion constitute a main steering system.

More specifically, the input shaft 31 has a serration groove 31a formed on the outer peripheral surface of the tip (upper end), and a constricted portion 31b provided midway in the longitudinal direction (near the tip) of the serration groove 31a. The torsion bar 33 has a tip fitted into the through hole 31d of the input shaft 31 and the input shaft 3
A large-diameter base portion 33a protruding from the front end of the first base portion 1 is formed, and the large-diameter base portion 33a extends below the constricted portion 31b. Tip of input shaft 31 and torsion bar 33
The large-diameter base portion 33a is formed by connecting the pin 32 at the distal end portion from the constricted portion 31b.

The steering torque detecting means 6 is provided between the input and output shafts 3.
The steering torque of the steering system is detected by detecting the relative torsion angles 1 and 34, and includes a torsion bar 33, a slider 35, a sensor 36, and a slider spring compression spring 37. See Torsion Bar 3
Numeral 3 is a member that literally generates a torsion angle with respect to torque, and generates a relative torsional displacement between the input shaft 31 and the output shaft 34. Cylindrical slider 35 having an inclined groove 35a and a vertically long straight groove 35b
Between the input shaft 31 and the output shaft 34, the slider 35 can be displaced in the axial direction according to the relative torsional displacement. The displacement at this time is proportional to the torque, and the displacement is converted into an electric signal by the variable inductance sensor 36. The input shaft 31, the torsion bar 33, and the output shaft 34 are concentric.

The steering gear box 21 has a first housing 41 and a second housing 42 assembled on an upper portion thereof, and the steering torque detecting means 6 and the input / output shafts 31, 34 are provided in the first and second housings 41, 42. Is stored. The rack shaft 5 extending in the front and back directions in this figure is provided with a rack 5a that meshes with the pinion 4. In the figure, reference numeral 43 denotes a bearing for supporting the input shaft 31;
45 is a bearing that supports the output shaft 34, and 46 is a rack guide.

FIGS. 4 (a) and 4 (b) are views showing the configuration of the distal end portion of the input shaft according to the present invention, wherein FIG. 4 (a) is a perspective view and FIG. The input shaft 31 is provided with two substantially parallel clamp surfaces 31c, 31c formed in a constricted portion (small diameter portion) 31b by a two-chamfering process for clamping. 3
1c has a straight portion long enough to be clamped, and is a surface conforming to the shape of a clamper to be described later, for example, a flat surface. The coupling position of the pin 32 is located at a tip portion of the clamp surfaces 31c, 31c and near the clamp surfaces 31c, 31c.

FIGS. 5 (a) and 5 (b) are views showing the configuration of a tip portion (modification) of the input shaft according to the present invention, wherein FIG. 5 (a) is a perspective view and FIG. FIG. In the modified example, the two clamp surfaces 31c, 31c substantially parallel to each other, are formed by circular grooves extending in a direction orthogonal to the axis of the input shaft 31, and the radius of curvature of these circular grooves is the outer peripheral surface of a round bar-shaped clamper described later. (Clamp surface) is approximately equal to the radius of curvature. (B)
As shown in the figure, two clamp surfaces 31 formed by arc grooves
c, 31c have the same extending direction of the groove, and as a result, can be said to be substantially parallel to each other.

FIGS. 6 (a) and 6 (b) are views showing the construction of a connecting portion between the input shaft and the universal joint according to the present invention.
(A) is a perspective view, (b) is the b arrow view of (a). The input shaft 31 is formed by serration-connecting the universal joint 23 to the tip and tightening the universal joint 23 with a bolt 24 passed along the constricted portion 31b. Since the bolt 24 is hooked on the constricted portion 31b, the universal joint 23 and the input shaft 31 do not come off.

Next, a device for neutral adjustment and pin connection of the electric power steering device 1 having the above configuration will be described.
A description will be given based on FIG. 7 and FIG. In this device, a subassembly A of an electric power steering device is neutrally adjusted and pin-coupled. The sub-assembly A is an assembly (the rack shaft 5 and the steering shaft 5 and the steering shaft) formed by assembling the steering torque detecting means 6 and the input / output shafts 31 and 34 shown in FIG. (Gearbox 21 removed).

FIG. 7 is a perspective view of the neutral adjustment / pin connection device according to the present invention. The neutral adjustment / pin connection device 50 includes a common base 51, a work clamp / neutral adjustment portion 52 attached to the common base 51, and , A hole processing portion 53 and a pin connecting portion 54. The work clamp / neutral adjustment unit 52 includes a slide base 61 mounted on the common base 51 so as to be slidable left and right, and a slide base 61.
A housing fixing jig 62, an input shaft fixing jig 63 and an output shaft fixing jig (collect chuck) 64 for setting the subassembly A horizontally, and an output shaft rotating motor 65 for rotating the output shaft 34. A torque meter 66 for measuring the torque of the output shaft 34, and a slide motor 67 for driving the slide base 61 to slide. Hole processing part 5
Reference numeral 3 includes a drill 53a and a reamer 53b. The pin connecting portion 54 presses the pin 32 into the input shaft 31 by hydraulic pressure.

In the neutral adjusting / pin connecting device 50 having such a configuration, after the neutral adjustment and the hole processing of the subassembly A set horizontally on the slide base 61, the slide base 61 is moved to connect the pins. Will do.
In the figure, 71 is a hydraulic pump, 72 is a coolant pump, 73 is a start operation box, 74 is an operation panel, 75 is a control panel, 76
Is an XY recorder.

FIG. 8 is a sectional view of a main part of an input shaft fixing jig according to the present invention. An input shaft fixing jig 63 is provided with a pedestal 81 installed on a slide base 61 and a vertically rotatable rotation of the pedestal 81. And a hydraulic drive unit 83 that presses and drives the clamp arm 82.
The lower clamper 84 provided on the pedestal 81 and the upper clamper 85 provided on the clamp arm 82 form a constricted portion 31b of the input shaft 31 (the clamp surface 31c shown in FIGS. 4 and 5).
31c) is clamped up and down. In the figure, 86
Is a support base for supporting the input shaft 31.

FIGS. 9 (a) and 9 (b) show the lower part according to the present invention.
FIG. 4 is a perspective view illustrating a configuration example of an upper clamper. The lower and upper clampers 84 and 85 in (a) are formed of round bars, and clamp the clamp surfaces 31c and 31c formed of the arc grooves in FIG. The lower and upper clampers 84 and 85 in (b) are made of rods having a substantially wedge-shaped cross section, and clamp the flat clamping surfaces 31c and 31c in FIG. The lower and upper clampers 84 and 85 may be rods having a substantially rectangular cross section.

Next, the neutral adjustment and the pin connection procedure of the electric power steering apparatus 1 having the above configuration will be described with reference to FIGS.
1 will be described. It should be noted that the adjustment / combination procedure has been described for facilitating the understanding of the above configuration, and is not limited to this procedure. FIG. 10 is an operation view showing a state where a subassembly is set in the neutral adjustment / pin coupling device according to the present invention. FIG. 11 is a flowchart of the neutral adjustment and pin connection procedure according to the present invention, where STxx indicates step numbers. Hereinafter, the operation will be described with reference to the operation diagram of FIG. 10 and the flowchart of FIG. 11.

ST01: The subassembly A is set horizontally on the neutral adjustment / pin coupling device 50. Specifically, the first
-The second housings 41 and 42 are fixed to the housing fixing jig 62.
, The input shaft 31 is placed on the support base 86, and the output shaft 34 is
Is fixed to the output shaft fixing jig 64. And the input shaft 31
Air-blowing the part to be clamped, and connect the performance measuring harness to the sub-assembly A.

ST02: Clamp surface 31 of input shaft 31
c, 31c are clamped by lower and upper clampers 84, 85. The clamping force at this time is 700 kgf. ST03: Mechanical neutral adjustment of the steering torque detecting means 6 is performed. Specifically, the output shaft rotating motor 65 of FIG. 7 is rotated to adjust the neutral point of the slider 35 with respect to the relative torsion angle between the input / output shafts 31 and 34. This adjustment data is X-
It is recorded on the Y recorder 76. ST04: If the result of the neutral adjustment is good, proceed to the next step; otherwise, return to ST02.

ST05: Electric neutral adjustment of the steering torque detecting means 6 is performed. Specifically, the output shaft rotating motor 65 in FIG. 7 is rotated to adjust the electrical neutral point of the variable inductance sensor 36 with respect to the relative torsion angle between the input / output shafts 31 and 34. ST06: If the result of the neutral adjustment is good, proceed to the next step; otherwise, return to ST02.

ST07: Lower and upper clampers 84, 85
Is increased to 2000 kgf, and the input shaft 31 and the torsion bar 33 are temporarily tightened (caulked). Thus, the input shaft 31 is located at the positions of the clamp surfaces 31c, 31c.
And the torsion bar 33 are caulked, so that the mechanical and electrical neutral state of the steering torque detecting means 6 can be easily maintained. Further, there is no fear that the neutral point or the like of the steering torque detecting means 6 is shifted due to vibration generated at the time of pin hole processing or pin press-fitting described later. Further, there is no need to clamp the torsion bar 33 with a different clamping member.

ST08: Temporarily measure the performance of the steering torque detecting means 6. Specifically, with the input shaft 31 and the torsion bar 33 fixed, the output shaft rotating motor 65 of FIG.
To measure the mechanical and electrical performance of the steering torque detector 6 with respect to the relative twist angle between the input / output shafts 31 and 34. This adjustment data is recorded on the XY recorder 76. ST09: If the performance is good, proceed to the next step; otherwise, return to ST02.

ST10: Input shaft 31 and torsion bar 3
3 and a pin hole 31e is opened with a drill 53a. In this case, the pin hole 31e is formed at the tip of the clamp surface 31c. ST11: After finishing the pin hole 31e with the reamer 53b,
Wash with air blow. ST12: The subassembly A is moved to the position of the pin connecting portion 54 by sliding the slide base 61 of FIG. The input shaft 31 and the torsion bar 33 are connected by press-fitting the pin 32 into the pin hole 31e.

Since the connecting position of the pin 32 is near the clamp surfaces 31c, 31c, the support span from the lower and upper clampers 84, 85 is extremely short. Therefore,
When the pin hole 31e is machined by the drill 53a and the reamer 53b, the input shaft 31 hardly bends. For this reason, the pin hole processing accuracy is good, and the relative positional relationship between the input shaft 31 and the torsion bar 33 does not shift. As a result, there is no fear that the neutral point of the steering torque detecting means 6 shifts.

ST13: Lower and upper clampers 84, 85
Is adjusted to 1300 kgf. ST14: The final performance of the steering torque detecting means 6 is measured. Specifically, while the input shaft 31 and the torsion bar 33 are fixed, the output shaft rotating motor 65 of FIG. 7 is rotated, and the steering torque detecting means 6 for the relative twist angle between the input / output shafts 31 and 34 is rotated. Measure mechanical and electrical performance. This adjustment data is recorded on the XY recorder 76. ST15: If the performance is good, proceed to the next step; otherwise, proceed to ST18.

ST16: Remove the subassembly A from the neutral adjustment / pin coupling device 50. ST17: Move to the next step as a subassembly A having good performance of the steering torque detecting means 6. ST18: Remove the subassembly A from the neutral adjustment / pin coupling device 50. ST19: Process as a sub-assembly A having poor performance of the steering torque detecting means 6. Thus, the neutral adjustment and the pin connection work of one sub-assembly A are completed.

In the above embodiment of the present invention,
The substantially parallel clamping surfaces 31c, 31c provided on the constricted portion 31b of the input shaft 31 are a pair of surfaces for clamping the input shaft 31, and in addition to a pair,
Multiple pairs may be used. Further, the clamp surfaces 31c, 31
The shape of c may be any surface that matches the shape of the lower and upper clampers 84 and 85 for clamping the input shaft 31.
Further, the steering torque detecting means 6 includes input / output shafts 31, 3
What is necessary is just to detect the relative torsion angle between the four, and for example, a configuration of a potentiometer may be used.

[0034]

According to the present invention, the following effects are exhibited by the above configuration. According to the first aspect of the present invention, a steering torque detecting means for detecting a relative torsion angle between an input and an output shaft is provided between an input shaft and an output shaft via a torsion bar, and information of the steering torque detecting means is provided. An electric power steering device that generates an auxiliary torque based on the input shaft, wherein a constricted portion is provided in the vicinity of the distal end of the input shaft, and the constricted portion is provided with substantially parallel clamping surfaces for clamping, and the distal end portion is located closer to the distal end than these clamping surfaces. And the torsion bar is connected with a pin.

The input shaft can be easily and reliably clamped by clamping the substantially parallel clamping surfaces of the constricted portion. Therefore, when the input shaft and the torsion bar are connected to each other with a pin, the relative positional relationship between the input shaft and the torsion bar does not deviate due to vibration generated at the time of pin hole processing or pin press-fitting. Therefore, since the input shaft and the torsion bar can be pin-coupled with an accurate positional relationship, there is no fear that the neutral point or the like of the steering torque detecting means is shifted. In addition, since the input shaft and the torsion bar are pin-connected at the tip of the clamp surface to be clamped, there is no concern that the neutral point of the steering torque detecting means may shift due to vibrations generated during pin hole processing or pin press-fitting. Absent. As described above, since the neutral point or the like of the steering torque detecting means does not shift, the input shaft and the torsion bar can be accurately pin-coupled.

[Brief description of the drawings]

FIG. 1 is a system diagram of an electric power steering device according to the present invention.

FIG. 2 is an overall configuration diagram of an electric power steering device according to the present invention.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a configuration diagram of a tip portion of an input shaft according to the present invention.

FIG. 5 is a configuration diagram of a tip portion (modification) of the input shaft according to the present invention.

FIG. 6 is a configuration diagram of a connection portion between an input shaft and a universal joint according to the present invention.

FIG. 7 is a perspective view of a neutral adjustment / pin coupling device according to the present invention.

FIG. 8 is a sectional view of an essential part of the input shaft fixing jig according to the present invention.

FIG. 9 is a perspective view showing a configuration example of a lower / upper clamper according to the present invention.

FIG. 10 is an operation view showing a state where a subassembly is set in the neutral adjustment / pin coupling device according to the present invention.

FIG. 11 is a flowchart of a neutral adjustment and pin connection procedure according to the present invention.

FIG. 12 is an explanatory view of a method of connecting a pin of an input shaft and a torsion bar of a general electric power steering device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric power steering device, 2 ... Steering handle, 6 ... Steering torque detection means, 8 ... Electric motor, 31 ...
Input shaft, 31a ... serration groove, 31b ... constriction,
31c: clamping surface, 31d: through hole, 32: pin, 3
3 ... torsion bar, 34 ... output shaft, A ... partial assembly.

Claims (1)

[Claims] 1. A steering torque detecting means for detecting a relative torsion angle between an input and an output shaft between an input shaft and an output shaft via a torsion bar, and based on information of the steering torque detecting means, In an electric power steering apparatus for generating an auxiliary torque, a constricted portion is provided near a tip of the input shaft, and substantially parallel clamping surfaces for clamping are provided in the constricted portion. An electric power steering device wherein the bars are connected by pins.