JPS61201101A - Angle sensor for power steering - Google Patents

Abstract

PURPOSE:To obtain a small-sized durable device by linking the operating shaft and the driving shaft with a spring steel shaft in the magnetic circuit and constituting the magnetic circuit through a magnetic pole by the electromagnet. CONSTITUTION:When a driving shaft 2 is fixed to the neutral position, an operating shaft 1 is rotated in the left or right direction, the torque due to the displacement of the steel shaft 4 is gradually increased, and the position to which a stopper shaft 3 contacts with a slot 1c, namely, the rotating angle goes to be T, and then, the torque to the shaft 2 is directly communicated and increased. At such a time, when the central angle between the tooth shape and the tooth shape is made into 2T respectively and a wave shape 9a and a wave shape 10a are faced by an angle T only, the tooth shape 10a is turned in the right or left direction, thereby the facing area is gradually made larger or smaller, and the magnetic resistance of the magnet circuit is increased. As this result, by impressing a constant voltage from the constant alternating current voltage source to the circuit, amplifying the voltage of the resistance by an amplifier and obtaining the output voltage, thus, the servo motor to execute the power steering is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an angle sensor for power steering of an automobile, and more particularly to a small sensor for detecting the operating angle of electric power steering of a passenger car.

[Background of the invention]

In recent years, power steering using servo motors has come to be widely used in automobile steering, but in order to control the drive of this servo motor, the shaft that transmits the steering angle to the axle is divided into an operating shaft and a drive shaft. -
A common method is to elastically connect these axes and detect the torque during steering as a relative angle of deviation between these two axes to control the servo motor. Various proposals have been made in the past as means for detecting this relative deviation angle C (referred to as the operating angle), such as the U.S.P.
As described in No. 4,173,265 (N(IV, 6.1979)), the operation shaft and the drive shaft are connected with an elastic body, and a permanent magnet and a differential magnetic field sensor are provided on each, and the operation shaft is connected via a ribbon connector. A method has been proposed for detecting and controlling the operation of a servo motor, but this proposal has the problem that the ribbon connector becomes fatigued when the handle is operated many times, so the ribbon connector must be durable. Ta. In addition, this proposal requires a large space because the drive shaft is connected to the inner diameter of the operating shaft via an approximately cylindrical elastic body, and no consideration was given to reducing the space as in passenger cars. .

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its object is to provide a compact and durable angle sensor for power steering.

[Summary of the invention]

The present invention configures a magnetic circuit by providing opposing disc-shaped magnetic poles with phase-shifted tooth profiles on opposing surfaces on each of the operating shaft and the driving shaft that make up the power steering for an automobile. In order to convert the relative deviation angle between the operating shaft and the drive shaft into an electric signal as a change in coil impedance due to a change in magnetic resistance, and to miniaturize the angle sensor. The operating shaft and the driving shaft are connected by a stopper shaft that is loosely fitted into the operating shaft through an elongated hole and fixed to the drive shaft, and the stopper shaft and the driving shaft are connected in the axial direction by a spring steel shaft. The spring steel shaft is fixed integrally at right angles to the operating shaft, and the spring steel shaft is attached to the operating shaft so as to impart torque to the operating angle to achieve the intended purpose.

[Embodiments of the invention]

An embodiment of the power steering angle sensor according to the present invention will be described below with reference to the drawings.

An embodiment of the present invention is shown in FIGS. 1, 2, and 3.
A blind hole 1b into which the drive shaft 2 is fitted is formed on the inner diameter side of the enlarged diameter flange portion 1a at the bottom of the operation shaft 1.
The upper end of the drive shaft 2 is fitted into this hole 1b. A long hole 1 into which a stopper shaft 3 is inserted is provided on the outer periphery of the flange portion 1a.
c passes through the center of the operating shaft 1 and is formed at right angles to this operating shaft 1, and the stopper shaft 3 also passes through the center of the shaft near the upper end of the driving shaft 2 and is formed at right angles to this driving shaft 2. It is press-fitted into the through hole 2a. Therefore, although the stopper shaft 3 is fixed to the drive shaft 2, a space X is formed between the operation shaft 1 and the elongated hole 1c.

Rotation within this range is possible. Through holes 3a and 2b are formed in the stopper shaft 3 and the drive shaft 2, respectively, at right angles to the axial direction.
A spring steel shaft 4 is press-fitted into a and 2b to prevent relative movement between the stopper shaft 3 and the drive shaft 2. Both ends of this spring steel shaft 4 are inserted into a spring steel shaft mounting hole 1d formed in the flange portion 1a of the operating shaft 1 and having an inner diameter larger than the outer diameter of the spring steel shaft 4. It is fixed to the flange portion 1a via. Therefore, when the operating shaft 1 is rotated, the spring steel shaft 4 is elastically deformed within the space Y within the mounting hole 1d, and torque is transmitted to the drive shaft 2. This drive shaft 2 is rotatably supported by a fixed case 7 via a bearing 6.
is designed to steer wheels (not shown) via a transmission mechanism (not shown).

Next, a sensor for detecting the relative angle of deviation between the operating shaft 1 and the drive shaft 2 will be described. A ring-shaped distance piece 8 made of a non-magnetic material such as brass is press-fitted into the upper part of the drive shaft 2, and a ring-shaped distance piece 8 made of a magnetic material with teeth 9a formed on the upper surface is further attached to the outer periphery of this distance piece 8. A ring-shaped magnetic pole 9 is press-fitted and fixed. Further, a ring-shaped magnetic pole 10 made of a magnetic material and having a tooth profile 10a formed on the lower surface in the figure is fixed at a position facing the magnetic pole 9 at the lower end of the operating shaft 1. They are arranged opposite to each other and are out of phase with each other. An electromagnet 15, which is made by winding a coil 12 around a coil bobbin 11 and sandwiching it between a yoke 13 and an end bracket 14, is fixed to a cover 16 that is fixed to the fixed case 7 with screws (not shown). A magnetic circuit is formed which extends through the operating shaft 1, the tooth profile 10a of the magnetic pole 10, and the tooth profile 9a of the magnetic pole 9 to the end bracket 14 with a gap 17 in between.

The operation of this embodiment configured as described above will be explained below. As shown in Fig. 4, when the drive shaft 2 is fixed at the neutral position, as the operating shaft 1 is rotated to the right or left, the torque due to the displacement of the spring steel shaft 4 gradually increases, and the stopper shaft The torque to the drive shaft 2 is directly transmitted and increases only when the rotation angle reaches T, that is, the position where the drive shaft 3 contacts the elongated hole IC.

At this time, the tooth profile 9a and the tooth profile 10a are set so that the center angle between the tooth profile and the tooth profile is 2T, respectively, as shown in FIGS. If they are made to face each other, as the tooth shapes 10a rotate to the right or left, the opposing areas will gradually increase or decrease, respectively, and the magnetic resistance of the magnetic circuit will increase or decrease. and the tooth profile 10a up to the angle T.
When rotated, the opposing area becomes maximum or minimum. As a result, as shown in FIG. 7, a constant voltage is applied from a constant AC voltage source 18 to a circuit including a coil 12 and a resistor 19 in series, and the voltage across the resistor 19 is amplified by an amplifier 20, as shown in FIG. This output voltage can be used to control the servo motor that performs power steering.

As described above, according to this embodiment, the relative angle of deviation can be detected even when the operation shaft 1 and the drive shaft 2 rotate, and the flexibility due to large deformation of the elastic body as in the conventional example can be detected. There are no parts, so there is little chance of damage even if the number of operations is increased. Furthermore, since the operation shaft 1 and the drive shaft 2 are coupled within the magnetic circuit by a relatively small spring steel shaft, the entire sensor can be made smaller.

〔Effect of the invention〕

As mentioned above, according to the present invention, the operation shaft and the drive shaft are connected by a small spring steel shaft within a magnetic circuit for detecting the angle of deviation, and the magnetic circuit is connected through magnetic poles having tooth profiles provided on each shaft. Since it is constructed using an electromagnet, it is possible to provide a small and durable angle sensor for power steering.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, FIG. 3 is a view taken along arrow B in FIG.
The figure is a graph showing the relationship between the rotation angle of the operating shaft and the torque applied to the drive shaft, FIGS. 5 and 6 are partial plan views showing tooth profile portions provided on the drive shaft and the operating shaft, respectively, and FIG. The figure is a detection circuit diagram, and FIG. 8 is a graph showing the relationship between the rotation angle of the operating shaft and the output voltage, which shows the characteristics of the sensor. 1 ・Operation shaft, IC...long hole, LD...spring steel shaft mounting hole. 2... Drive shaft, 2a, 2b, 3a... Through hole, 3.
...Stopper shaft, 4...Spring steel shaft, 5...Fixing bracket, 9゜10...Magnetic pole, 9a, 10a...Tooth profile, 15
...electromagnet, 17...gap.

Claims (1)

[Claims] 1. In a power steering angle sensor that magnetically detects a deviation angle between an operating shaft and a drive shaft that are elastically connected, an angle sensor that is arranged concentrically with each of the operating shaft and the drive shaft. Almost disk-shaped magnetic poles are provided at opposing positions and have tooth profiles formed with a phase shift on these opposing surfaces, and magnetic poles are provided on the outer periphery of these magnetic poles and are connected to each other through a gap between the magnetic poles and the magnetic poles. An angle sensor for power steering characterized by being provided with an electromagnet constituting a magnetic circuit. 2. In a power steering angle sensor that magnetically detects the deviation angle between an operating shaft and a drive shaft that are elastically connected, the sensor is fitted loosely into a long hole formed perpendicular to the axial direction of the operating shaft. , a stopper shaft fixedly installed in a through hole formed perpendicularly to the axial direction of the drive shaft; and a spring steel fixedly installed through each of the operation shaft, the drive shaft, and the stopper shaft perpendicularly to the axial direction. An angle sensor for power steering characterized by having a shaft. 3. The inner diameter of the spring steel shaft mounting hole formed in the drive shaft is larger than the outer diameter of the spring steel shaft, and both ends of the spring steel shaft are fixed to the drive shaft via fixing fittings. An angle sensor for power steering according to claim 2, characterized in that: