JPH03224867A - Electromagnetic booster - Google Patents

Abstract

PURPOSE:To minimize effect at the time of breakdown of an electromagnetic type magnification device that is utilized as a motor-operated type power steering device or the like, by controlling an electric current, which is controlled at a value in accordance with input torque, according to the presence or absence and operation direction of input torque by means of a changeover switch. CONSTITUTION:The rotor 10 of a motor 9 is provided around an output shaft 6 which is arranged coaxially with an input shaft 1 given steering torque by a steering wheel, and which is connected with the input shaft 1 through a torsion bar 15. This rotor 10 is rotated with a pair of magnets 40 provided on the inner perimeter surface of a case 2, and transmits its rotation to the output shaft 6 through a planetary gear deceleration device 48, and gives the auxiliary power of steering to the output shaft 6. The current flowed in the rotor 10 is controlled by an electric current value control means consisting of a transistor circuit, and a changeover switch 68 responding to the presence or absence and direction of input torque, on the basis of the output of a torque sensor 65 containing a detection plate 24 that links with the relative rotation of input and output shafts 1, 6.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electromagnetic booster used as an electric power steering device for an automobile.

(Prior art) An electromagnetic booster has an electric motor inside, and operates the electric motor when rotational torque is applied to the input shaft, generates auxiliary torque, and outputs large rotational torque to the output shaft. have

Conventionally, as this type of electromagnetic booster, one described in US Pat. No. 3,983,953 and the like is known. This electromagnetic booster uses a torsion bar to connect an input shaft connected to a steering wheel and an output shaft connected to a steering wheel so that they can rotate relative to each other, and to respond to the relative rotation direction of these input and output shafts. A switch for detecting the relative rotation angle of the input and output shafts is provided, and these switches and sensors are connected to a computer to control the electric motor, and the electric motor assists steering.

(Problem to be Solved by the Invention) However, in the conventional electromagnetic booster described above, the output signals from the switches and sensors are processed by a computer to control the motor, so the computer may malfunction. A computer failure can have a large impact on the entire system. Therefore, it is necessary to add various devices as a countermeasure against a computer failure, and there is a problem that the apparatus as a whole becomes complicated.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electromagnetic booster whose overall configuration can be simplified.

(Means for Solving the Problems) The present invention provides an electromagnetic booster that controls a DC motor based on the direction and magnitude of input torque applied to an input shaft to provide auxiliary torque to an output shaft. a changeover switch that controls the presence or absence and direction of current flowing to the DC motor in response to the presence or absence and direction of the input torque; a torque sensor that detects the magnitude of the input torque; and a torque sensor that detects the magnitude of the input torque, based on the output signal of the torque sensor. The gist is that a current value control means for controlling the value of the current flowing through the DC motor is provided, and the current value control means and the changeover switch are connected in series.

(Function) In the electromagnetic booster of the present invention, the presence or absence of energization of the electric motor is determined by the operation of the changeover switch, that is, the presence or absence of input torque by the driver. If the changeover switch is not operated, no current is applied to the motor, and the influence of failure of the current value control means can be minimized. Therefore, the number of devices added as a countermeasure against failure can be reduced, and the entire apparatus can be simplified.

(Embodiment) A preferred embodiment of the present invention will be described below based on the accompanying drawings.

In Figure 1, 1 is the input shaft, and this input shaft 1 is connected to the case 2.
Bearing 4 supported by end plate 3 fixed to the right end opening of
is rotatably supported by.

The input shaft 1 is surrounded by a steering column 5 fixed to the outer surface of the end plate 3, and has a steering wheel at its outer end. Therefore, the input shaft 1 is given a steering torque (input torque) from the steering wheel.

6 is an output shaft, and the output shaft 6 is connected to the cylindrical case 2.
It is rotatably supported by a bearing 8 on an annular diaphragm 7 attached to the inside of the diaphragm. Inside the case 2, a rotor 10 of an electric motor 9 is provided concentrically around the output shaft 6.
The cylindrical shaft 11 of 0 is rotatably supported by a bearing 12, and a needle-shaped bearing 13,
14 is interposed to enable rotation of the output shaft 6 and the cylindrical shaft 11.

The inner ends of the input shaft 1 and the output shaft 6 that face each other are
The end of the input shaft 1 is inserted into the hole at the end of the output shaft 6 so that they are in fitting engagement with each other, and the torsion bar 1 is an elastic member.
They are connected by 5. Therefore, when the input shaft 1 rotates, the torque is transmitted to the output shaft 6 while being twisted by the torsion bar 15.

Next, flanges 16 and 17 are fixedly installed on the outer peripheral surfaces of the fitting portions of the input shaft 1 and the output shaft 6, respectively.
For example, three planetary gears 18..., 19... having the same number of teeth are rotatably supported on each of the gears 6.17, and a common ring-shaped internal gear 20 is arranged outward in the radial direction. This internal gear 20 is equipped with a planetary gear 18.
..., 19... are internally meshed, and sun gears 21 and 22 having the same number of teeth are meshed with each planetary gear. Here, the sun gear 22 is fixed to the partition plate 7, while the sun gear 21 has a flange portion 21a and is rotatably provided. The right side edge of the internal gear 20 in FIG.

The mechanism of the planetary gears 18, 19, sun gears 21, 22, and internal gear 20 produces the following effects. First, when no relative rotation occurs between the input shafts 1.6, the sun gear 21 is held stationary regardless of the rotation of the input and output shafts 1.6. However, if the input shaft 1 is twisted relative to the output shaft 6, a relative rotational angle difference will occur between the flanges 16, 17, so that the sun gear 21 is It rotates in the same direction with respect to the fixed side at a rotation angle larger than the relative rotation angle of 16. That is, the relative rotation angle generated between the input shaft 1 and the output shaft 6 is amplified and produced as the rotation angle of the sun gear 21.

A detection plate 24 is provided on the right side of the flange 21a of the sun gear 21.
can be installed. This detection plate 24 rotates together with the sun gear 21.

A front view of the detection plate 24 is shown in FIG. Semi-circular arc-shaped conductor plates 25 and 26 are provided at symmetrical positions on the inner peripheral edge of the detection plate 24, and arc-shaped resistance plates 27 and 28 are provided at symmetrical positions on the outer peripheral edge of the detection plate 24. It will be done. Contactors 29.30 are provided for the conductor plates 25.26, and the contacts 29.30 abut on the detection plate 24 at symmetrical positions as shown in FIG. It is supported by a spring plate 32 fixed to a fixed mounting plate 31.

The contacts 29.30 are located in the gap between the conductor plates 25.26 when there is no relative angular difference between the input shaft 1 and the output shaft 6, and when there is a relative angular difference, the respective contacts 29.30
contacts the conductive plate 25 or 26 and slides. Contact 29.
Conductive wires 33 and 34 are connected to 30, and terminals a and b are drawn out, while conductive wires 35 and 35 are connected to the center point of conductive plate 25 and 26.
．． 36 is connected, and terminals c and d are pulled out. Further, the resistance plates 27, 28 are provided with contacts 37, 38, which are similarly supported by spring plates fixed to the mounting plate 31. The contactor 37.38 is normally located in the center position of the resistive plate 27.28, and when the input/output 1.6 rotates with twisting, the resistive plate 27
．． 28. The center point of contactor 27 and contactor 38
are connected, and the center point of the resistor plate 28 is also installed. According to the connection relationship between the resistance plate 27.28 and the contactor 37.38, when a relative angle difference occurs between the input and output shafts 1.6, the contactor 37.38 moves from the center point of the resistance plate 27.28. A resistance value is generated in proportion to this distance. As long as the contact 37.38 is at the center point of the resistive plate 27.28, the resistance is zero.

The resistance plates 27, 28 and contacts 37, 38 described above constitute a torque sensor 65, and the conductor plates 25, 26 and contacts 29, 30 constitute a changeover switch 68.

The electric motor 9 includes, for example, a pair of magnets 40 and 40 arranged at symmetrical positions on the inner peripheral surface of the case 2, and the rotor 10 rotatably mounted on the output shaft 6. Therefore case 2
forms the yoke of the electric motor.

Further, in the rotor 10, a laminated iron core 4 is attached to the cylindrical shaft 11.
1 is provided, and a rotor winding 42 is provided thereon. The terminals of the rotor winding 42 are connected to a commutator 43, and a power supply brush 44 is pressed into contact with the commutator 43. The brush 44 is supported by a coil spring 47 in a brush holder 46 attached to the square plate 7 via an insulating plate 45, and is brought into sliding contact with the commutator 43.

A planetary gear reduction device 48 is provided on the left side of the case 2 in FIG.
Consists of. The gear 50 formed at the left end of the leading edge 11 of the planetary gear mechanism 48A in the previous stage is a sun gear. In the planetary gear mechanism 48B at the latter stage, the gear 52 formed on the cylindrical shaft 51a of the first carrier 51 is used as a sun gear. Then, the cylindrical shaft 53a of the second carrier 53 is fixed to the output shaft 6 with a bolt 54. Further, the planetary gears 55 . . . , 56 .

9 The torque generated by the electric motor 9 is reduced in speed via the reduction gear device 48 and transmitted to the output shaft 6.

A lid 59 is attached to the left end opening of the case 2 with screws 58.

Next, the control circuit will be explained based on FIG.

60 is a battery, and current from the battery 60 is supplied via a key switch 61 and a fuse 62 to a transistor circuit (current value control means) 63 consisting of two stages of transistors. On the other hand, the constant current outputted from the constant current circuit 64 is applied to the torque sensor 65, and the terminal voltage (2) generated at the torque sensor 65 is inputted to the non-inverting terminal of the operational amplifier 66. As mentioned above, the torque sensor 65 has a variable resistance value depending on the input torque, and the resistance plate 2
This is the resistance synthesized by 7.28.

The output terminal of the operational amplifier 66 is connected to the control terminal 63a of the transistor circuit 63 via a resistor 67. The output terminal 68b of the transistor circuit 63 is connected to the changeover switch 68.
The terminal C of the selector switch 68 is connected to the upstream terminals 68a and 6810-a2. Furthermore, the downstream terminals 68b□ and 68b2 of the changeover switch 68 are connected to the terminal d, and the terminals a and b are connected to the electric motor 9. The terminal d is grounded through a resistor 69, and the terminal voltage 2 generated across the resistor 69 is input to the inverting terminal of the operational amplifier 66. The changeover switch 68 has terminal a.

As is clear from the relationships b, c, and d, the functions of the conductor plates 25, 26 and the contacts 29, 30 of the detection plate 24 are electrically shown, and the relative relationship between the input shaft 1 and the output shaft 6 is terminal 68a depending on the direction of rotation, that is, the direction of action of the input torque.
1, 68b2 and 68a2, 68b2 are selectively connected to terminal a.

b, to switch the direction of armature current to the motor 6, and to stop energizing the motor 9 when the rotation angle relative to the input shaft 6 is O1, that is, the input torque is O.

In the electromagnetic booster of this embodiment, when a relative angle difference occurs between the input shaft 1 and the output shaft 6, the detection plate 24
As the resistance value of the torque sensor 65 increases, a voltage V proportional to the input torque is generated in the torque sensor 65.

This voltage v4 is input to the transistor circuit 63 via the operational amplifier 66, controls the armature current, and supplies it to the motor 9. At this time, the changeover switch 68
．． 26 and contacts 29 and 30, they are connected in a desired positional relationship, and the electric motor 9 rotates in the same direction as the rotation direction of the input shaft 1. The voltage v2 produced by the armature current across the resistor 69 is fed back to the operational amplifier 66. If the armature current flows too much due to this feedback, the armature current will be controlled.

In this electromagnetic booster, a transistor circuit 63 and a changeover switch 68 are connected in series between the battery 60 and the electric motor 9, and the transistor circuit 63 switches the current controlled to a value according to the input torque. The switch 68 turns on and off and switches the current direction depending on the presence and direction of input torque.

Therefore, even if a failure occurs in the transistor circuit 63 (particularly an ON failure) or a failure occurs in the operational amplifier 66, the electric motor 9 will be energized unless the driver applies input torque to the steering wheel. This does not occur, and the influence of failures in the transistor circuit 63 and the like is extremely small. Therefore, as a countermeasure against a failure, it is sufficient to simply add, for example, a device for controlling excessive current, and the overall configuration does not become complicated with failure countermeasure devices.

(Effects of the Invention) As is clear from the explanation below, according to the present invention, the changeover switch and the current value control means are connected in series between the power supply and the electric motor, and the input torque is controlled by the current value control means. Since the current is controlled to a value according to the current value and the current is turned on or off using a changeover switch depending on the presence or absence of input torque and the direction of action, failures have occurred in the current value control means or sensors, etc. Even if the driver does not operate the steering wheel, the electric motor will not be energized.
The influence of failures can be extremely minimized, and failure countermeasures can be simplified.

[Brief explanation of drawings]

=13 Figure 1 shows a longitudinal section of the electromagnetic booster according to the present invention,
In the electric motor section, the cutting line is bent 90 degrees to form a vertical cross-section, Figure 2 is a front view of the detection plate, and Figure 3 is the
The sectional view taken along the line A-A in the figure and FIG. 4 are control circuit diagrams. In the drawing, 1 is an input shaft, 5 is a steering column, 6 is an output shaft, 9 is an electric motor, 10 is rotating, 15 is a torsion bar, 24 is a detection plate, 25.26 is a conductor plate, and 27.28 is a resistance plate. , 63 is a transistor circuit (current value control means);
65 is a torque sensor, and 68 is a changeover switch. Patent applicant: Honda Motor Co., Ltd. Agent
Person Patent Attorney Part 2 1) Part 1 Patent Attorney
Kuni Ohashi Patent Attorney Koyama
4 Japanese Patent Publication No. 3-224867 (5)

Claims (1)

[Claims] In an electromagnetic type booster that controls a DC motor based on the direction and magnitude of input torque applied to the input shaft to provide auxiliary torque to the output shaft, the DC motor is A changeover switch that controls the presence or absence of energizing current to the motor and the direction of energization, a torque sensor that detects the magnitude of the input torque, and a current value that controls the value of the energizing current of the DC motor based on the output signal of this torque sensor. 1. An electromagnetic booster comprising: a control means, and the current value control means and the changeover switch are connected in series.