JP2741388B2 - Relative displacement detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relative displacement detection device that detects a relative change between a first shaft and a second shaft, and is particularly suitable for an electric power steering device. The present invention relates to a relative displacement detection device.

[Prior Art] Conventionally, after detecting a torsion direction and a change amount among relative angle changes of a first shaft body and a second shaft body connected via a torsion bar (torsion bar) which is a continuous body. An apparatus configured to apply a driving force having a direction and a change amount according to a detection result of a relative angle change to the second shaft body has been proposed. As an application example thereof, an electric power steering apparatus has been proposed. Are known.

The relative displacement detecting device of the electric power steering device includes a first shaft body, that is, an input shaft to which the rotational force of a steering wheel steered by a driver is directly transmitted, and a second shaft body including a steering gear. An output shaft connected to the device, and a relative displacement detecting device for detecting a relative angle between the first shaft body and the second shaft body that changes according to the magnitude of the load of the steering force is provided. However, as such a relative displacement detecting device, a sliding contact type device is mainly used.

The sliding contact type includes a detecting portion composed of a sliding contact and a resistance wire for detecting a change in relative angle between the input shaft and the output shaft, a first shaft member and a second shaft member. And a take-out portion constituted by a brush and a slip ring for taking out the detection result of the relative angle between the main body and the main body.

Japanese Utility Model Application Laid-Open No. 63-122226 and Japanese Utility Model Application Laid-Open No. 63-121387 have also been proposed as types of position detection devices used in such power steering devices.

Since the detection part and the take-out part are based on a sliding contact principle, the slip ring is subjected to a gold plating process or the like in consideration of vehicle safety standards, and is excellent in temperature characteristics but expensive. Thoroughness was ensured by forming resistance wires on the ceramic substrate.

Since the sliding contact type relative displacement detection device thus configured is expensive and has poor reliability and durability, the applicant of the present application claims that it is expensive and poor in reliability and durability. Japanese patent application for a relative displacement detector that solves the problem
63-24454 (Japanese Patent Laid-Open No. 2-9332).

[Problems to be Solved by the Invention] However, since the magnetic sensor provided in the relative displacement detecting device proposed in this way is provided so as to be sandwiched in the magnetic circuit, the accuracy of the mutual positional relationship is ensured. In particular, there is a first problem that the degree of freedom in assembling is significantly limited.

On the other hand, the output of the magnetic sensor provided in the relative displacement detection device is obtained by detecting the change and the change amount of the movement amount of the number K tooth-like bodies provided at intervals of the angle in the radial direction: θ by the magnetic sensor. As a result of amplification, pulsation occurs in accordance with the number of teeth of the magnetic core, so that the second problem that detection becomes unstable, and an abnormal state such as breakage of the magnetic sensor cannot be detected. There was a third problem.

Therefore, the relative displacement detection device of the present invention has been made in view of the above-described problems, and its purpose is to improve the degree of freedom in assembling, and to use a magnetic sensor. It is an object of the present invention to provide a relative displacement detection device that enables stable detection without causing pulsation in the detected displacement and the amount of change.

Further, in addition to the above object, it is an object of the present invention to provide a relative displacement detection device that can detect an abnormal state such as breakage of a magnetic sensor by obtaining an output from the magnetic sensor as a voltage change.

[Means for Solving the Problems] In order to solve the above-mentioned problems and achieve the object, a relative angle detecting device of the present invention has the following configuration. That is,
A first shaft rotatably supported by the housing; a multipolar magnetized permanent magnet fixed to the first shaft; and a first shaft rotatably supported by the housing and rotatably supported by the housing. A second shaft body disposed to face the shaft body, a magnetic core fixed to the second shaft body and having a tooth-shaped body corresponding to the multipolar magnetization number, and fixed to the housing; And a magnetic sensor sandwiched by a magnetic member disposed near an outer peripheral surface of the magnetic core, the relative displacement detecting device comprising: a relative displacement between the permanent magnet and the magnetic core; The resulting change in magnetic flux is defined as the direction of relative position change and the amount of change in displacement about the rotation axis of the first shaft body and the second shaft body,
In order to detect by the magnetic sensor, the angle K in the radial direction as the number K of the teeth is θ:
The magnetic sensor is a pair of first magnetic sensor and second magnetic sensor, and the first magnetic sensor and the second magnetic sensor are radially angled to each other: It is characterized by being provided at a distance.

Further, an output result obtained by operatively amplifying the positive output of the first magnetic sensor and the negative output of the second sensor, and an output obtained by operatively amplifying the negative output of the first magnetic sensor and the positive output of the second magnetic sensor. By obtaining a voltage change from the result, the torsion angle is measured, and the abnormal state of the first magnetic sensor and the second magnetic sensor can be detected by the abnormality detection of the voltage change.

[Operation] With the above configuration, the direction of relative position change and the amount of change in displacement of the first shaft body and the second shaft body around the rotation axis are changed by the permanent magnet fixed to the first shaft body and the second shaft. When a change in magnetic flux between the magnetic cores fixed to the body occurs, the pulsation is generated by a pair of magnetic sensors fixed to the housing and clamped by a magnetic member disposed near the outer peripheral surface of the magnetic core. It becomes possible to prevent and detect.

Further, an output result obtained by operatively amplifying the positive output of the first magnetic sensor and a negative output of the second sensor and an output result obtained by operatively amplifying the negative output of the first magnetic sensor and the positive output of the second magnetic sensor are used. In addition, an abnormal state of the first magnetic sensor and the second magnetic sensor can be detected.

Examples Examples will be described below in detail with reference to the drawings.

First Embodiment FIG. 1 (A) is a center sectional view of a relative displacement detecting device of a first embodiment, and FIG. 1 (B) is a sectional view taken along line XX of FIG. .

In both figures, a lower end of the first shaft body 1 is connected to a rotating means (not shown) or the like, and is rotatably supported by a bearing 101 of the main body 100.

In the vicinity of the upper end portion, multi-pole magnetized magnet wheels 4 and 40 having the outer diameter of the first shaft body 1 as the inner diameter are fixed as shown in the figure.

The upper end surface of the first shaft 1 is provided with a hole for inserting and fixing a torsion bar 3 shown by a dashed line in the figure. And the torsion bar 3 are integrally formed.

That is, the turning operation of the first shaft body 1 becomes the turning operation of the magnet wheels 4 and 40.

On the other hand, at the lower end of the second shaft body 2 which is rotatably supported by the bearing 101 of the main body 100, a hole for inserting and fixing the above-mentioned torsion bar body 3 is formed.
As shown in the drawing, the first shaft 1 and the second shaft 2 are integrally rotated via a torsion bar 3.

On the other hand, the flange body 7 having the lower surface 7A is fixed to the second shaft body 2 and is configured to be integrated with the second shaft body 2. A lower tooth-shaped core 80 made of a magnetic material is provided on the lower surface 7A of the flange body 7, and the lower tooth-shaped core 80 and an upper tooth-shaped core 8 described later are a single tooth-shaped core plate. The magnetic flux is prevented from wetting outside.

Here, the above-mentioned tooth-shaped core plate is not necessarily required to be a single structure, but may be a structure in which a plurality of tooth-shaped core plates are stacked.

A spacer 9 made of a non-magnetic material is provided below the lower tooth-shaped core 80. The upper and lower surfaces of the spacer 9 are made of a magnetic material,
The upper tooth-shaped core 80 and the upper tooth-shaped core 8 are integrally provided via the spacer 9 as shown in FIG.

The above-mentioned magnet wheels 4 and 40 are provided such that the magnet wheel 4 and the upper tooth-shaped core 80 have the same positional relationship in the vertical direction, as shown in the figure, and the magnet wheel 40 and the upper tooth-shaped core 80 respectively. .

Next, the magnetic sensor 11 wired on the substrate 110 is provided so as to be sandwiched between sensor members 6 and 60 made of a magnetic material as shown in the figure. The tooth-shaped core 80 is provided in the main body 100 at a position close to the outer peripheral surface.

Therefore, even if the above-described tooth-shaped core, shaft, and the like rotate, the magnetic sensor 11 fixed to the main body 100 does not move. Further, the magnetic sensor 11 provided so as to be sandwiched between the sensor members 6 and 60 can be incorporated from the rotation axis direction of the shaft body, and the degree of freedom in design and assembly is increased.

Next, FIG. 1 (B) shows the positional relationship between the magnet wheel 4, the upper tooth-shaped core 8 and the lower tooth-shaped core 80. In the figure, the first shaft 1 and the second shaft 2 are shown. Are in a neutral state with respect to each other, and the magnet wheel 4 is, as shown,
A total of twelve magnet parts 4B are arranged in the concentric circle direction of the first shaft body 1 and alternately magnetized to the N pole and the S pole, and have an inclination of 30 degrees in the radial direction. Is multi-polarized.

Here, the magnet part is not limited to the above-described twelve parts, and the detection angle can be made finer or rougher by increasing or decreasing the number of magnetized poles, that is, by changing the division angle of the circumference in the radial direction. Needless to say, this is possible.

On the other hand, as shown, the upper tooth-shaped core 8 and the lower tooth-shaped core 80 each formed by laminating a plurality of plate-shaped magnetic materials have a total of six core pieces 8A and six core pieces 80A, respectively. The change in magnetic flux of the magnet wheels 4 and 40 is detected by the tip of the core piece 8A, and these core pieces 8A and 80A are provided at intervals of an angle θ (60 degrees in the figure) as shown in the figure. .

Next, the aforementioned magnetic sensor 11 is a pair of magnetic sensors 11A, 1A.
The magnetic sensor 11 is provided between the sensor members 6 and 60 as 1B, and these magnetic sensors 11 have an angle of 30 degrees as shown in FIG. It is provided at a distance. Thus, a pair of magnetic sensors
By providing 11A and 11B, pulsation of the output of the magnetic sensor 11 generated according to the number of teeth of the tooth-shaped core is corrected.

Here, the example in which the six core pieces 8A and 80A are formed in total at intervals of 60 degrees has been described above as the first embodiment, but as described above, the core pieces are detected as the number increases. Accuracy is improved.

In order to describe the generality, when the interval at which the core pieces are provided is an angle θ and the number of the core pieces is K, the above 1
The angle at which the pair of magnetic sensors 11A and 11B is provided is represented by the following equation.

In other words, in the case where the interval between the core pieces is set to the angle θ of 60 degrees as described above, when K = 6, the angle in the radial direction is set to 30 degrees so that the number of teeth generated according to the number of teeth of the tooth-shaped core is increased. The pulsations in the output of the magnetic sensor 11 cancel each other, thereby eliminating the influence of the pulsation.

[Second embodiment] Fig. 2 (A) is a center sectional view of a relative displacement detecting device of a second embodiment, and Fig. 2 (B) is a sectional view taken along line XX of Fig. 1.

In both figures, the basic configuration is the same as that of the first embodiment described with reference to FIG. 1. Therefore, the same parts are denoted by the same reference numerals as those in FIG. 1, and the description is omitted. I will explain only.

First, in FIG. 2 (A), as shown, the magnet wheel 4 is alternately magnetized in the N-pole and the S-pole toward the concentric direction of the first shaft body 1 and has a radial angle of 60 degrees. Multi-pole magnetization is performed such that six inclined magnet portions 4B are arranged in total.

On the other hand, from the upper tooth-shaped core 8 and the lower tooth-shaped core 80 which are formed by laminating a plurality of plate-shaped magnetic materials, the core piece 8A and the core piece 80A are formed as shown in FIG. Three pieces are formed so as to surround the surface, and a total of six pieces are formed, and a change in magnetic flux of the magnet wheel 4 is detected by the tips of the core pieces 8A and 80A.

With this configuration, only one magnet wheel 4 is required, and the core pieces 8A and 80A face all the magnet portions 4B of the magnet wheel 4; As described in the embodiment, the magnetic force of the magnet portion 4B is transmitted to the core pieces 8A and 80A very efficiently as compared with the configuration in which the magnetic force generated from the magnet portion 4B is transmitted to every other core piece 8A and 80A. Will be done.

In addition, the magnetic sensor 11 is disposed based on the above equation, so that the magnetic sensor 11 is generated according to the number of teeth of the tooth-shaped core.
The pulsation of the output of 11 is corrected.

Third Embodiment FIG. 3A is a center sectional view of a relative displacement detection device of a third embodiment, and FIG.
It is X sectional view taken on the arrow.

In both figures, the basic configuration has been described with reference to FIG. Since there is no difference from the first embodiment, the same parts are denoted by the same reference numerals as in FIG. 1 and the description is omitted, and only different parts will be described.

In FIG. 3 (A), as shown, the magnet wheel 4 is alternately magnetized in the longitudinal direction of the first shaft body 1 with the north pole and the south pole, and the radial direction has an inclination of 60 degrees. The magnet portion 4B is multipolar magnetized so that the magnet portions 4B are arranged to be a total of six portions.

On the other hand, the upper tooth core 8 and the lower tooth core 80 formed by laminating a plurality of plate-shaped magnetic materials form a core piece 8A and a core piece 80A as shown in FIG. , Three in total, and six in total, are formed so that the change in magnetic flux of the magnet wheel 4 is detected by the tips of the core pieces 8A, 80A.

With this configuration, only one magnet wheel 4 is required, and the core pieces 8A and 80A face all the magnet portions 4B of the magnet wheel 4; As described in the embodiment, as compared with the configuration in which the magnetic force generated from the magnet portion 4B is transmitted to every other core piece 8A, 80A, the magnetic force of the magnet portion 4B is very efficiently transferred to the core pieces 8A, 80A.
It will be transmitted to A.

In addition, the magnetic sensor 11 is disposed based on the above equation, so that the magnetic sensor 11 is generated according to the number of teeth of the tooth-shaped core.
The pulsation of the output of 11 is corrected. FIG. 4 shows a pulsation waveform diagram of the output of the magnetic sensor 11. Since the phases of the output waveforms (11A) and (11B) from the magnetic sensor 11 are opposite to each other, it is shown that they cancel each other based on a reference voltage a described later.

Next, FIG. 5 is an operation amplification circuit diagram of an example connected to the relative displacement detection device having the above-described configuration.

In FIG. 5, the magnetic sensor 11 composed of a magnetoresistive element (MR element) and a Hall element is a magnetic sensor 11A as described above.
And a magnetic sensor 11B. Among these sensors, a voltage signal obtained by amplifying the positive output of the magnetic sensor 11A and the negative output of the magnetic sensor 11B by the amplifier A2 is used as a subsidiary output S, while the magnetic sensor A voltage signal obtained by operating and amplifying the negative output of the magnetic sensor 11B and the positive output of the magnetic sensor 11B with the amplifier A1 is output as the main output M.

The main output M and the slave output S are sent to a comparator 50 to obtain a final output signal.

Here, RN indicates a resistor, A1 and A2 indicate amplifiers such as transistors, and input signals having polarities input to the amplifiers A1 and A2 are indicated by b, c, d, and e, respectively.

FIG. 6 is a signal waveform diagram in the operational amplifier circuit diagram shown in FIG.

As shown in FIG. 6, the input signals b, c, d, and e are
The output waveforms of the main output M and the slave output are output as the waveforms passing through the reference voltage a and the reference angle 0 °, respectively, as shown in FIG. .

When an abnormal trouble such as breakage occurs in one of the magnetic sensor 11A and the magnetic sensor 11B, an output waveform that is substantially coincident with the main output M and the sub output S during normal operation is indicated by a broken line. Waveform indicated by F1 and broken line
Since output waveforms separated into the waveform indicated by F2 are output, these waveforms are detected by the comparator 50,
It is possible to detect the occurrence of abnormality.

[Effects of the Invention] As described above, the relative displacement detection device of the present invention provides a relative displacement detection device that can improve the degree of freedom during assembly, does not generate pulsation in the detection result, and can detect stably. can do.

Further, it is possible to provide a relative displacement detection device capable of detecting an abnormal state such as breakage of the magnetic sensor.

[Brief description of the drawings]

1 (A) is a central sectional view of the relative displacement detecting device of the first embodiment, FIG. 1 (B) is a sectional view taken along the line XX of FIG. 1, and FIG. 2 (A) is a second embodiment. FIG. 2 (B) is a sectional view taken along line XX of FIG. 1, and FIG. 3 (A) is a central sectional view of the relative displacement detection device of the third embodiment. 3 (B) is a sectional view taken along the line XX of FIG. 3 (A), FIG. 4 is a pulsation waveform diagram of the output of the magnetic sensor 11, and FIG. FIG. 6 is a signal waveform diagram in the operational amplifier circuit diagram shown in FIG. 5 as an example of an operational amplifier circuit connected. In the drawing, 1... The first shaft body, 2... The 2nd shaft body, 3... A torsion bar, 4, 40...
Sensor member, 7: Flange body, 8: Upper tooth-shaped core, 50: Comparator, 80: Lower tooth-shaped core, 8A, 80A ...
... Core piece, 9 ... Spacer, 11, 11A, 11B ... Magnetic sensor, 100 ... Main body, 110 ... Substrate, 101 ... Bearing, a ...
Reference voltage, b, c, d, e: input signal, K: number of core pieces, θ: angle.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shigekazu Nakamura 2-16-20 Shimura, Itabashi-ku, Tokyo Inside Copal Co., Ltd. (56) References JP-A-56-107140 (JP, A) JP-A-63 JP-A-2769 (JP, A) JP-A-58-73833 (JP, A) JP-A-56-157810 (JP, A) JP-A-1-202669 (JP, A) JP-A-58-219411 (JP, A) ) JP-A-63-253218 (JP, A)

Claims (2)

(57) [Claims] A first shaft rotatably supported by a housing;
A multi-pole magnetized permanent magnet fixed to the first shaft body, and a second shaft body rotatably supported by the housing and opposed to the first shaft body. A magnetic core fixed to the second shaft body and having a toothed body corresponding to the number of multipolar magnetizations; and a magnetic core fixed to the housing and disposed near an outer peripheral surface of the magnetic core. A relative displacement detection device comprising a magnetic sensor sandwiched between magnetic members, wherein a change in magnetic flux caused by a relative displacement between the permanent magnet and the magnetic core is determined by the first shaft member and the second shaft member. In order to detect, by the magnetic sensor, the direction of the relative position change and the change amount of the displacement around the rotation axis of the body, K teeth are provided in the radial direction at an angular interval of θ: The magnetic sensor is a pair of a first magnetic sensor and a second magnetic sensor Angle in the radial direction between the first magnetic sensor and the second magnetic sensor with each other: A relative displacement detection device, which is provided at a distance. 2. The method of operating the positive output of the first magnetic sensor and the negative output of the second sensor, and operating the amplified result, and operating the negative output of the first magnetic sensor and the positive output of the second magnetic sensor. By obtaining a voltage change from the amplified output result, the torsion angle is measured, and the abnormal state of the first magnetic sensor and the second magnetic sensor can be detected by detecting the abnormality of the voltage change. The relative displacement detection device according to claim 1.