JPH1178923A - Comparison switch of electric power steering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To convert a steering torque into a mechanical displacement amount with a simple structure by forming a comparison switch which displaces according to an output from an input torque detector with a pair of electrodes which have arc-shaped contacts and installed rotatably about a center shaft and brushes which are brought in contact with the contacts of the electrodes. SOLUTION: A comparison switch 50 is structured so that it compares the amount of displacement according to an output from a steering torque detector with the amount of displacement according to an output from a proportional solenoid which detects an additional torque of an assist motor for controlling a control range. Also it is provided with first and second electrodes 70 and 80 which are provided with arc-shaped contacts 73 and 83, a close-fitted tube part of which is installed rotatably about the center shaft 54 in a case 51, and one side surface of which is pressed against a stopper 61. Then, during steering, the electrode 70 or 80 is rotated through a driving lever 59 in a judgment direction so as to detect whether the current carrying condition through a brush 89 which displaces according to an output from the proportional solenoid, i.e., an assist torque is appropriate or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a comparison switch in an abnormality detection control device of an electric power steering system for improving operability by adding an assist torque to a steering torque when a steering wheel is operated.

[0002]

2. Description of the Related Art In a conventional electric power steering system, as disclosed in, for example, Japanese Patent Application Laid-Open No. 64-56274 or Japanese Patent Application Laid-Open No. 2-293260, an electric power steering system uses steering signals and assist torques as electric signals. And convert them into electric control units (hereinafter referred to as ECUs).
Is controlled by

[0003] The ECU, together with these control circuits,
A failure detection mechanism and an assist prohibition mechanism are provided.
That is, when the relationship between the steering torque and the assist torque exceeds the permissible range, the two are compared by software to detect a failure, and further, the assist inhibition control is performed based on this detection signal.

The ECU of this electric power steering system is provided with a control circuit for calculating an assist torque from a steering torque, as well as an electrically configured failure detecting mechanism and an assist inhibiting mechanism. Since hardware and software are required, there is a problem that the system becomes complicated and costs increase.

[0005] The applicant discloses in Japanese Patent Application No. 9-32302 a basic invention which solves these problems.
An object of the present invention is to convert a steering torque and an assist torque into a mechanical displacement amount, directly compare these, and integrate a failure detection mechanism and an assist prohibition mechanism to expand a control allowable range.

[0006]

SUMMARY OF THE INVENTION In the above-mentioned invention, there is provided a means for efficiently transmitting the mechanical displacements of the steering torque and the assist torque to a comparison switch. There is a new problem that a small size is required. As a result of extensive research, the applicant
The present invention has been completed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a comparison switch of an electric power steering system capable of converting a steering torque into a mechanical displacement with a simple configuration. is there.

[0008]

Means adopted by the present invention to solve this problem are denoted by the reference numerals used in the embodiments and will be described. An input torque detecting device for detecting the steering torque of the steering wheel 1 will be described. 20, a proportional solenoid 30 for detecting an additional torque of the assist motor 10 corresponding to a detection signal of the input torque detecting device 20, and a displacement and proportional solenoid 30 corresponding to an output of the input torque detecting device 20.
In the electric power steering system having a comparison switch 50 for comparing a displacement amount corresponding to the output of the motor and managing a control range, the comparison switch 50 is provided with a stopper 61 on a peripheral portion and a center shaft 54 is attached. The case 51 and the fitting cylindrical portion 71a having an arc-shaped contact 73 are fitted to the center shaft 54 of the case 51 so as to be rotatably mounted around the center shaft 54, and one side surface is provided to the stopper 61. A first electrode 70 to be pressed and an arc-shaped contact 83 have a fitting cylindrical portion 81a.
The electrode 70 is fitted around the outer periphery of the fitting tube portion 71a, and the center portion 71d of the first electrode 70 is accommodated in the concave portion 81d at the upper end of the fitting tube portion 81a so as to rotate around the center axis 54 of the case 51. Then, the second electrode 80 whose one side surface is pressed against the stopper 61 and the respective contact points 7 of the first and second electrodes 70 and 80.
3 and 83, and the brush 89 is displaced in accordance with the output of the proportional solenoid 30, so that both electrodes 70, 8
0 is rotationally displaced inside the case 51, so that the whole can be made smaller than in the case of linear movement.
Since the members 3 and 83 move on the same plane, the manufacture of the brush 89 in contact with the members 3 and 8 is simplified.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. First, the electric power steering system will be described with reference to FIGS. When the steering wheel 1 is operated, the steering torque is transmitted to the input shaft 3 of the gear case 2 and drives the rack 5 via the pinion at the lower end of the output shaft 4. This rack 5 changes the direction of wheels 7 via a steering link 6.

On the other hand, a torque sensor 8 attached to the gear case 2 detects a steering torque, and an electric signal thereof is input to an electric control device (hereinafter referred to as an ECU) 9. Then, based on a signal from the ECU 9, the assist motor 10
Is driven. The assist motor 10 has a motor shaft 1
A worm gear 12 is connected to the worm wheel 1, and assist torque is transmitted to the rack 5 via a worm wheel 13 meshing with the worm gear 12 and a pinion (not shown) integrated with the worm wheel 13. The rack 5 includes the output shaft 4 of the steering wheel 1 and the assist motor 1.
Since it is driven by the zero output shaft 14, operability is significantly improved. In this embodiment, a speed reducer using a worm gear is used. However, the present invention is not limited to this, and any structure may be used as long as the speed reducer is used.

Next, a torsion bar type input torque detecting device 20 for detecting a steering torque will be described with reference to FIGS. The input shaft 3 and the output shaft 4
Each is rotatably attached to the gear case 2. The upper end of the torsion bar 21 is integrated with the input shaft 3 by the pin 22, and the lower end is integrally press-fitted into the hole 4 a of the output shaft 4. Therefore, the torque input to the input shaft 3 is transmitted to the output shaft 4 via the torsion bar 21.

On the other hand, a sleeve 23 is fitted outside the input shaft 3. The sleeve 23 has a long groove 24 parallel to the axial direction and an inclined groove 25. Then, a pin 26 fixed to the output shaft 4 is inserted into the long groove 24,
A pin 27 fixed to the input shaft 3 is inserted into the inclined groove 25. That is, the sleeve 23 moves in the axial direction with respect to the output shaft 4, but does not rotate in the circumferential direction.

Here, the steering torque is changed from the input shaft 3 to the output shaft 4.
When the torque is transmitted to the torsion bar 21, a torsion angle is generated in the torsion bar 21, and a circumferential displacement occurs between the input shaft 3 and the output shaft 4. Therefore, the pin 27 fixed to the input shaft 3 moves in the inclined groove 25, and the sleeve 23 is raised in the axial direction by a predetermined amount, for example, the dimension H. Input torque detector 2
Numeral 0 indicates that the dimension H is taken out as a detection amount, and a groove 28 is formed on the outer peripheral surface of the sleeve 23.

Next, a proportional solenoid 30 for detecting the additional torque of the assist motor 10 will be described with reference to FIGS. The housing 31 has a bottomed cylindrical shape, and a rotor shaft 33 is rotatably attached to a ball bearing 32 attached to the center. Actuator 34
Is formed by winding coils 36 around four magnetic poles of a core 35, respectively, and a stator pipe 37 press-fitted at the center is inserted into a rotor shaft 33 and fixed to the housing 31. Both ends of the coil 36 are attached to a terminal block 38 of the housing 31, and are connected to the assist motor 10 in series.

The permanent magnet 39 has a bottomed cylindrical yoke 40.
It is attached to the inner peripheral part. The central portion of the yoke 40 is fixed to the lower end of the rotor shaft 33, whereby the permanent magnet 39 is rotatably arranged on the outer peripheral portion of the actuator 34. Slot 4 on the bottom of the yoke 40
1 is formed, and a pin 42 projecting from the actuator 34 is inserted into this, thereby regulating the rotation angle of the yoke 40.

The upper end of the rotor shaft 33 projects from the housing 31 to the opposite side of the actuator 34, and the center of the spiral spring 43 is fixed here. Further, the outer peripheral free end of the spiral spring 43 is fixed to the housing 31 via a fixing frame 44. The position where the fixing frame 44 is fixed to the housing 31 can be arbitrarily changed along the spiral spring 43 (shown by a two-dot chain line in FIG. 5).
As a result, the effective length of the spiral spring 43 changes,
The spring constant of the spiral spring 43 can be adjusted.

Note that the cover 4 is so covered as to cover the spiral spring 43.
5 is attached to the housing 31. A brush 89 of the comparison switch 50 described later is attached to the outer bottom of the yoke 40 via an insulating plate 46.

Next, the comparison switch 50 will be described with reference to FIGS. The case 51 has a cylindrical shape, and mounting pieces 52 are provided on both side surfaces at the center. Cylindrical parts 51a and 51b are provided above and below the mounting piece 52, respectively.
However, a bearing 51c is formed at the center. The displacement lever 53 includes a lever shaft 54 that also functions as a central shaft.
And a disk 55 fixed to the end of the lever shaft 54 in the cylindrical portion 51b, and a pin 56 protruding from the peripheral edge of the disk 55. The displacement lever 53 is rotatably attached to the case 51 with the lever shaft 54 fitted in the bearing portion 51c.

The spring 57 includes a case 51 and a displacement lever 53.
, The displacement lever 53 is urged in one direction, and when the comparison switch 50 is mounted on the input torque detecting device 20, the pin 56 is engaged with the groove 2 of the sleeve 23.
8 without any gap. A drive disk 58 is fixed to an intermediate portion of the lever shaft 54 in the cylindrical portion 51a, and a drive lever 59 is attached to an end of the drive disk 58. A terminal block 60 is attached to the edge of the case 51, and both end surfaces of the terminal block 60 serve as stoppers 61.

In the case 51, a first electrode 70 and a second electrode 80, which form a pair on both sides of the terminal block 60, are disposed with their side surfaces facing each other. The first electrode 70
When the steering wheel 1 is operated in one direction, for example, in the right direction, the steering lever 1 is driven in the clockwise direction in FIG. The second electrode 80 is driven counterclockwise when the steering wheel 1 is operated in another direction, for example, leftward. These will be described below.

The first electrode 70 includes a first holder 71
And a first contact board 72 made of an insulating plate fixed to the upper surface of the first holder 71. The first contact board 72 has a Z-shaped first contact 73 on the surface thereof. It is arranged in one state. The first contact 73 is formed such that an arcuate contact 73a on the inner periphery is short and an arcuate contact 73b on the outer periphery is long, and both are connected by a connection piece 73c.

The first holder 71 has a fan shape, and has a fitting cylinder 71a projecting from the center thereof, and the fitting cylinder 71a is fitted to the lever shaft 54. The first holder 71 is provided with a large-diameter large rib 71b and a small-diameter small rib 71c protruding concentrically, between which the first contact substrate 72 is inserted so as to be movable in the circumferential direction. ing.
After the position of the first contact 73 is adjusted as desired, the first contact board 72 is fixed to the first holder 71 by screws 75 inserted into the two long holes 74.

Incidentally, one reference line 76a is engraved on the first holder 71 and a plurality of reference lines corresponding to the reference line 76a are formed on the first contact board 72 so as to be a guide for position adjustment. The scale line 76b is engraved. This first electrode 70
Is biased in the center direction by a spring 77 inserted into the lever shaft 54, and the contact portion 78 on the outer peripheral edge is in contact with the stopper 61.

The second electrode 80 is connected to a second holder 81
And a second contact board 82 made of an insulating plate fixed to the upper surface of the second holder 81. A Z-shaped second contact 83 is formed on the surface of the second contact board 82. It is arranged in one state. Like the first contact 73, the second contact 83 has a short inner circumferential contact 83 a and a longer outer circumferential contact 83 b, and both are connected by a connecting piece 83 c. ing.

The second holder 81 has a fan shape which is symmetrical to the first holder 71, and a fitting cylinder portion 81a protruding from the center portion is fitted to the fitting cylinder portion 71 of the first holder 71.
a. The central portion 71d of the first holder 71 is accommodated in a concave portion 81d formed at the upper end of the fitting tube portion 81a.

The second holder 81 is also provided with a large-diameter large rib 81b and a small-diameter small rib 81c protruding concentrically, during which the second contact board 82 can move in the circumferential direction. Has been inserted. Then, the second contact board 8
After adjusting the second contact point 83 to a desired position, 2 is fixed to the second holder 81 by screws 85 inserted into the two long holes 84. Note that, similarly to the first electrode 70, a reference line 86a and a graduation line 86b are provided on the second holder 81 and the second contact board 82 as a guide for position adjustment.

The second electrode 80 has a
The contact portion 88 on the outer peripheral edge is in contact with the stopper 61 by being urged in the center direction by a spring 87 inserted into the fitting tube portion 81a.

The contact portion 78 of the first electrode 70 and the second
A drive lever 59 is inserted between the contact portions 88 of the electrodes 80 so that both side portions contact each other.

Two contact pieces 62 are attached to the terminal block 60, and the tips of the two contact pieces 62 are in contact with a contact 73a inside the first contact 73 and a contact 83a inside the second contact 83, respectively. .

The brush 89 is attached to the outer bottom of the yoke 40 of the proportional solenoid 30 via the insulating plate 46. It has contact pieces 89a projecting from both ends of the base, and the ends of the contact pieces 89a are respectively connected to the first contacts 7a.
The third contact 73b and the second contact 83 are in contact with the outer contact 83b. The two lead wires 63 shown in FIG. 2 are connected to the terminal block 60. The brush 89 and the contact piece 62 are in an energized state while they are in contact with the contacts 73 and 83, and are disconnected when separated. Switch to power state.

The comparison switch 50 includes a displacement lever 53
Is inserted into the groove 28 of the sleeve 23 of the input torque detecting device 20, and the mounting piece 52 of the case 51 is fixed to the input torque detecting device 20. Next, the housing 31 of the proportional solenoid 30 is mounted on the periphery of the other surface of the case 51.
And the brush 89 is brought into contact with the contact points 73b and 83b, and the housing 31 is fixed to the case 51 with screws (not shown). As a result, the proportional solenoid 30 is assembled concentrically with the comparison switch 50.

According to the comparison switch 50, the following effects can be obtained. (1) The fitting cylindrical portion 81a of the second electrode 80 is
The first electrode 70 and the second electrode 80 rotate around the central axis of the case 51 since the first electrode 70 and the second electrode 80 have been fitted into the fitting cylinder portion 71a. Therefore, it is possible to easily compare the output of the proportional solenoid 30 with the concentrically rotating brush 89 converted.

(2) In addition, since the central portion 71d of the first electrode 70 is accommodated in the concave portion 81d at the upper end of the fitting cylindrical portion 81a, the first electrode 70 and the second electrode 80 are connected to the first electrode 7
0 are arranged on the same plane. Therefore, the assembly is easy, and the height of the tip of the brush 89 can be easily adjusted.

(3) Further, the first electrode 70 and the second electrode 80 are arranged with their side surfaces facing each other and move alternately in opposite directions, so that the moving space can be shared, and the entirety can be used. Can be downsized.

Here, the procedure by which the comparison switch 50 manages the control range will be described. The detection amount of the input torque detection device 20 based on the steering torque (the first and second electrodes 70,
The relationship between the amount of movement of the brush 89 and the amount of detection of the second detection device 30 by the assist torque (the amount of movement of the brush 89) is shown in FIG.
Is controlled along the control line C shown in FIG. At this time, in FIG. 9, as will be described later, the control allowable range surrounded by qrstq'r's't 'is such that the contact 73 of the first electrode 70 and the contact 83 of the twenty-first electrode 80 are normal. The contact via the brush 89 indicates that the power supply line is energized and operates in a normal state. In a hatched portion beyond the control allowable range, the brush 89 is connected to the contact 73 of the first electrode 70 or the second contact.
This indicates that the power supply line deviates from the contact point 83 of the first electrode 80 and is switched to the cut-off state, and the abnormal state (fail area) occurs.

Next, the operation of the comparison switch 50 will be described with reference to FIGS. When the steering wheel 1 is operated to the right, the contact 73 of the first electrode 70 is moved clockwise in FIG. 7, and when the steering wheel 1 is operated to the left, the contact 83 of the 21st electrode 80 is turned counterclockwise. Moved in the direction. Since the operation is the same, a case where the steering wheel 1 is operated rightward will be described as an example.

1, when neither the steering torque nor the assist torque is applied (STEP 10 in FIG. 8),
, The contact 73 of the first electrode 70 and the 21st electrode 8 as shown in FIG.
The brush 89 is in contact with the zero contact point 83 and is in an energized state.

2. When the steering torque and the assist torque are in a normal relationship (moving along the control line C) (STEP
11) This corresponds to the point H in FIG.
And the brush 89 moves while maintaining the relationship shown in FIG. The brush 89 is connected to the contact 83 of the twenty-first electrode 80.
Although it moves upward, the energized state is maintained (FIG. 11). Then, when the brush 89 further moves and reaches the point J shown in FIG. 9, the power source is switched to the cut-off state beyond the contact point 73 of the first electrode 70 as shown in FIG. 12 (STEP 12).

3. When the assist torque is too large than the steering torque (STEP 13) The brush 89 advances faster than the contact 73 of the first electrode 70. The energized state is maintained until the brush 89 reaches the q't line (FIG. 11). When the brush 89 exceeds the q't line {point K (fail area) shown in FIG.
Reference numeral 9 passes through the contact 73 of the first electrode 70 and moves onto the insulating substrate, the power supply is turned off, and a failure is detected (FIG. 12).

4. If the assist torque is too small compared to the steering torque (STEP 13), the contact 73 of the first electrode 70 advances faster than the brush 89. The energized state is maintained until the brush 89 reaches the sr line (FIG. 11). Then, when the brush 89 exceeds the sr line {point L (fail area) shown in FIG. 9}, the brush 89 or the contact piece 62 passes through the contact 73 of the first electrode 70 and moves onto the insulating substrate, The power supply is turned off, and a failure is detected (FIG. 13).

5, when the assist torque acts in the opposite direction (STEP 14, FIG. 14) Since the brush 89 moves in the opposite direction, the brush 89
It is in an energized state until it reaches the r-line. And brush 8
When 9 exceeds the qr line {point M (fail area) shown in FIG. 9}, the brush 89 moves on the insulating substrate through the contact 83 of the 21st electrode 80, and the power supply is cut off,
Detect a failure.

Next, the control circuit and the fail-safe function will be described with reference to FIG. When the ignition switch 91 is turned on, the contact 92 of the engine starter interlock relay is turned on, and the DC power supply 93 is connected to the circuit. A relay coil 94 is connected in series to the engine starter contact 92. Even when the contact 92 of the engine starter interlocking relay is turned off, the contact 95 and the contact 96 are held by themselves. The contact 95 is connected in series to the comparison switch 50 and the relay coil 94,
The contact 96 is connected to the assist motor 10 and the proportional solenoid 30 in series. Note that a capacitor 97 is connected in parallel with the relay 94. Further, the contact 92 may be connected in parallel with the contact 95.

Next, in FIG. 16, when the steering wheel 1 is operated, the input torque detecting device 20 detects the steering torque, and the proportional solenoid 30 detects the assist torque. Then, the two are compared by the comparison switch 50 (STEP 20 in FIG. 16). If the relationship is within the control allowable range, the comparison switch 50 holds the energized state (STEP 24), and the power assist is continued.

On the other hand, when the relationship falls within the abnormal range, that is, when the vehicle enters the fail area, as described above, the comparison switch 50 detects a failure and enters a power cutoff state, and the relay 94 is turned off (STEP 21). The contacts 95 and 96 are simultaneously turned off. As a result, the motor 10 is turned off (STEP 22), the assist torque becomes zero, and the assist is prohibited. That is, when an abnormality is detected, the fail-safe function is activated to switch to manual steering (STEP 23).

In this embodiment, even if the comparison switch 50 is momentarily cut off due to a sudden steering wheel, vibration, or the like, the contact 95 is turned on for a time corresponding to the capacity of the capacitor 97.
Since the contact 96 is held by itself, the occurrence of erroneous failure can be prevented by that much.

[0046]

According to the electric power steering system of the present invention, the first and second electrodes of the comparison switch, which is displaced in accordance with the output of the input torque detecting device, are arranged so as to be rotatable around the central axis. Was easy to assemble,
The contact between the contact and the brush can be reliably made. Further, the present invention has an excellent effect that the entire device can be downsized.

[Brief description of the drawings]

FIG. 1 is a perspective view of a comparative switch and a proportional solenoid, partially cut away.

FIG. 2 is a vertical sectional front view of a comparison switch and a proportional solenoid.

FIG. 3 is an exploded view of a comparison switch and a proportional solenoid.

FIG. 4 is a plan view showing a relationship between an actuator of a proportional solenoid and a magnet.

FIG. 5 is a plan view of the proportional solenoid with a cover removed.

FIG. 6 is an exploded perspective view of first and second electrodes.

FIG. 7 is a plan view of first and second electrodes.

FIG. 8 is a flowchart illustrating a control mode of a comparison switch.

FIG. 9 is a graph showing an assist characteristic and a fail area.

FIG. 10 is a diagram illustrating a first state of the mechanical displacement of the comparison switch.

FIG. 11 is a diagram illustrating a second state of the mechanical displacement of the comparison switch.

FIG. 12 is a diagram illustrating a third state of the mechanical displacement of the comparison switch.

FIG. 13 is a diagram illustrating a fourth state of the mechanical displacement of the comparison switch.

FIG. 14 is a diagram illustrating a fifth state of the mechanical displacement of the comparison switch.

FIG. 15 is a control circuit diagram.

FIG. 16 is a flowchart showing control.

FIG. 17 is a block diagram illustrating a system.

FIG. 18 is a vertical sectional front view of a main part.

FIG. 19 is a vertical sectional front view of the input torque detection device.

FIG. 20 is a front view of a sleeve of the input torque detection device.

[Explanation of symbols]

 Reference Signs List 1 steering wheel 9 electric control device 10 assist motor 20 input torque detection device 30 proportional solenoid 50 comparison switch 51 case 53 displacement lever 54 lever shaft (center shaft) 59 drive lever 61 stopper 70 first electrode 71 first holder 71a fit Joint part 71d Central part 72 First contact board 73 Contact 80 Second electrode 81 Second holder 81a Fitting cylinder part 81d recess 82 Second contact board 83 Contact 89 Brush

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Yoshinori Ogiso, Inventor 2-4-1, Hamamatsucho, Minato-ku, Tokyo World Trade Center Building Kayaba Industry Co., Ltd. (72) Inventor Asahi Kani 2 Hamamatsucho, Minato-ku, Tokyo Chome 4-1 World Trade Center Building Kayaba Industry Co., Ltd.

Claims (1)

[Claims] An input torque detection device for detecting a steering torque of a steering wheel; a proportional solenoid for detecting an additional torque of an assist motor corresponding to a detection signal of the input torque detection device; and an output of the input torque detection device. An electric power steering system comprising: a comparison switch for managing a control range by comparing a displacement amount corresponding to the output of the proportional solenoid with a displacement amount corresponding to the output of the proportional solenoid. A case having a central axis attached thereto, a fitting cylindrical portion having an arc-shaped contact point fitted to the central axis of the case and attached rotatably around the central axis, and one side surface serving as a stopper. A first electrode to be pressed and an arc-shaped contact, a fitting cylinder portion fitted to the outer periphery of the fitting cylinder portion of the first electrode, and the first cylinder fits into the recess at the upper end of the fitting cylinder portion. electrode And the second electrode is rotated around a central axis of the case while one side surface thereof is pressed against a stopper, and the second electrode contacts the respective contacts of the first and second electrodes. A comparison switch for an electric power steering system, comprising: a brush that is displaced in accordance with an output of a solenoid.