JPH0618213A - Position sensor - Google Patents

Abstract

PURPOSE:To obtain a position sensor producing a digital value with desired different resolution for each detection range through a single A/D converter. CONSTITUTION:In a sensor for magnetically detecting throttle opening through a Hall element 21, output voltage from the Hall element 21 is amplified through two amplifier circuits 55, 57 having different amplification characteristic to produce voltage signals V1, V2, which are then fed to a subtractor circuit 59 where the differential voltage(V1-V2) is determined thus obtaining a detection signal VS which is nonlinear to the throttle opening. In the circuitry, detection characteristic of the sensor can be set arbitrarily depending on the amplification characteristic of the amplifier circuits 55, 57 and A/D conversion results with high resolution can be obtained only in a low throttle opening region, for example.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position sensor for detecting linear displacement and rotational displacement of an object to be measured.

[0002]

2. Description of the Related Art Conventionally, a voltage is applied to both ends of a resistor,
A potentiometer that slides on the resistor with a brush or the like connected to the object to be measured to electrically detect the displacement of the object to be measured, or, for example, as disclosed in JP-A-2-122205, 2. Description of the Related Art Various position sensors are known, such as a magnetic sensor in which a magnet is provided on an object to be measured and the displacement of the object to be measured is detected from the magnetic field strength and the magnetic field direction generated by the magnet.

[0003]

However, such a conventional position sensor outputs a detection signal which is a linear detection signal which changes linearly or sinusoidally with respect to the position of the object to be measured. Therefore, when the detection signal is A / D converted in order to digitally control the DUT, the A / D conversion result has a resolution that is uniform or proportional to the derivative of the linear function in the entire detection range of the position sensor. It will be.

Therefore, for example, even when a high resolution A / D conversion result is required only in a specific detection range, a high resolution A / D conversion result can be obtained in the entire detection range of the position sensor. It was necessary to use an available A / D converter. Further, by changing the A / D converter used in the detection range requiring a high-resolution A / D conversion result and the detection range other than that, the high-resolution A / D conversion is performed only in a specific detection range. The results can be obtained, but in this case multiple A / D converters are required.

The present invention has been made in view of these problems, and an object thereof is to provide a position sensor which can obtain a digital value of a desired resolution which is different for each detection range by using one A / D converter. I am trying.

[0006]

A position sensor according to claim 1, which has been made to achieve the above object, detects a position of an object to be measured and detects a position to generate a voltage signal corresponding to the detected position. Means for converting the voltage signal from the position detecting means into a non-linear voltage signal preset for the detection position, and outputting the voltage signal to the outside as a detection signal representing the position of the object to be measured. And a circuit.

According to a second aspect of the present invention, in the position sensor according to the first aspect, the signal processing circuit according to the first aspect is different in amplification characteristic with respect to an input voltage, and has a plurality of amplification circuits for amplifying the voltage signals from the position detection means. And an arithmetic circuit for adding or subtracting the voltage signals amplified by the plurality of amplifier circuits.

Further, the position sensor according to claim 3 is
The position sensor according to claim 1 or 2, further comprising temperature signal output means for detecting an ambient temperature and outputting a voltage signal according to the temperature to the outside.

[0009]

In the position sensor according to claim 1 configured as described above, the signal processing circuit detects the voltage signal corresponding to the position of the measured object output from the position detecting means. The voltage signal is converted into a non-linear voltage signal preset with respect to the position, and the voltage signal is output to the outside as a detection signal representing the position of the measured object.

Therefore, according to the position sensor of the first aspect, for example, when the object to be measured is in a predetermined detection area, the detection signal greatly changes with respect to the amount of displacement of the object to be measured, The change in the detection signal with respect to the displacement amount of the object to be measured becomes smaller as the value deviates from the predetermined detection area. It is possible to obtain a detection signal that changes non-linearly with the changing characteristics of.

Therefore, when a high resolution A / D conversion result is required in a specific detection area of the object to be measured, the detection signal should be changed greatly with respect to the displacement amount of the object to be measured in the detection area. With this, it becomes possible to obtain an A / D conversion result with a desired resolution by using one A / D converter without using a high resolution A / D converter. Therefore, it is possible to simplify the configuration of the control device that receives various detection signals from the position sensor and performs various controls.

In the position sensor according to the second aspect of the invention, a plurality of amplifier circuits having different amplification characteristics with respect to the input voltage respectively amplify the voltage signals output from the position detecting means, and the arithmetic circuit amplifies the voltage signals. By adding or subtracting the plurality of voltage signals, the voltage signal output from the position detecting means is converted into a non-linear voltage signal with respect to the detected position of the object to be measured. Therefore, by combining the amplification characteristics of the amplifier circuits, it is possible to freely set the non-linear characteristics with respect to the detection position of the detection signal, and as the number of amplification circuits used increases, Can be smooth.

Further, in the position sensor according to the third aspect, unlike the position sensor according to the first or the second aspect, not only the non-linear voltage signal is output with respect to the detected position, but also the temperature is detected. The signal output means outputs a voltage signal according to the ambient temperature to the outside. Therefore, on the control device side that receives various detection signals from the position sensor and performs various controls, the ambient temperature of the object to be measured can be known from the voltage signal from the temperature signal output means, and the temperature detection sensor can be used. It is not necessary to newly provide it, and the configuration of the control device can be simplified also by this.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. First, the configuration of a throttle position sensor for detecting the opening of a throttle valve (throttle opening) of an internal combustion engine of a vehicle, to which the present invention is applied, will be described with reference to FIGS. 3 to 5.

3 is a sectional view showing the internal structure of the throttle position sensor of this embodiment, FIG. 4 is a sectional view taken along the line ABCA in FIG. 3, and FIG. 5 is a throttle position sensor. It is a bottom view. As shown in FIGS. 3 to 5, the throttle position sensor of the present embodiment includes a resin-made hollow housing 1. A bearing 3 is embedded in the center of the housing 1, and a hollow rotor 5 made of a magnetic material is rotatably provided in the bearing 3. A lever 7 for receiving the rotation of the throttle valve is fixed to the lower end portion of the rotor 5 shown in FIG. 3, and a coil spring 9 is provided between the lever 7 and the housing 1.

As shown in FIG. 5, hook portions 9a and 9b are formed at both ends of the coil spring 9, and the hook portions 9a and 9b are formed on the housing 1, and the protrusion portion 1a and the lever 7 are respectively formed. It is locked in the groove portion 7a formed in. As a result, the coil spring 9 urges the lever 7 and the rotor 5, which rotate in conjunction with the throttle valve, in the throttle valve closing direction (arrow X direction).

On the other hand, a washer 10 is fixedly provided on the outer peripheral portion of the upper end of the rotor 5 in FIG.
Between the bearing 3 and the outer periphery of the upper end of FIG.
A wave-like elastic washer 11 is provided. That is, the washer 11 prevents the play in the Z direction shown in FIG. 3 from occurring.

The inner peripheral portion of the rotor 5 has an arc shape,
A pair of permanent magnets 15 and 16 made of a rare earth element such as Nd-Fe-B system magnetized so as to form a magnetic path from one magnet surface to the opposite magnet surface direction is fixed by magnetic force and adhesion. There is. Next, four feedthrough capacitors 17 are electrically connected and fixed by solder or the like above the permanent magnets 15 and 16 in FIG. 3, and a hole portion 20a is formed in the center,
A case 20 made of a non-magnetic conductive material is provided around which a mounting hole for the housing 1 is formed.

Further, above the case 20, a hall element 21, various circuit elements 23, and four terminals 24 are mounted, and a holder 25 accommodating the hall element 21 is fixed to a printed circuit board 27. Is provided. The case 20 and the printed circuit board 27 are
It is fixed to the housing 1 with a screw 29. The holder 25 is a printed circuit board 27 of the hall element 21.
For fixing and positioning.

Further, since the hall element 21 is positioned and fixed to the printed board 27 via the holder 25 in this manner, the position of the hall element 21 is determined by the above-described structure of the housing 1, the printed board 27 and the holder 25. In the present embodiment, in the Hall element 21, the centers of the permanent magnets 15 and 16 are the chip centers of the Hall element 21 on the rotation axis of the rotor 5 and are orthogonal to the rotation axis of the rotor 5, although this is determined by the dimensions and accuracy. It is designed to be in a position to sense a magnetic field.

Next, in the connector portion 31 of the housing 1,
The four connector terminals 32 connected to the four terminals 24 mounted on the printed circuit board 27 via the four feedthrough capacitors 17 fixed to the case 20 are provided. ,
It is possible to externally supply power to the various circuit elements 23 mounted on the printed circuit board 27 to operate the circuit elements 23, and to take out the detection signal obtained by this operation to the outside.

A rubber packing 34 is provided in the housing opening 1b above the printed circuit board 27 in FIG. 3, and a magnetic material cover 35 is further provided thereon.
These parts are fixed by caulking the periphery of the housing opening 1b. Printed circuit board 2
The upper part of FIG. 3 of FIG. 7 is filled or coated with a moisture-proof agent 36 such as a Humi-seal so as to protect the inside sealed by the rubber packing 34 from moisture. Further, as shown in FIG. 4, mating attachment portions 1c in which bushes 38 are embedded are formed at two locations outside the housing 1 and symmetrical with respect to the rotation axis of the rotor 5.

In the throttle position sensor of this embodiment constructed as described above, the lever 7 is connected to the rotary shaft of the throttle valve of the internal combustion engine, and the rotor 5 rotates with the rotation thereof. Then, with this rotation, the permanent magnets 15 and 16 rotate around the Hall element 21,
The magnetic field direction with respect to the magnetically sensitive surface of the Hall element 21 is shown in FIG.
It changes as shown in.

As a result, the output VH from the Hall element 21
Changes as in the following equation (1): VH = VA.sin θ (1) As shown in FIG. 6 (b), the rotor 5 moves from −90 ° to +90.
A linear voltage signal that continuously changes on the sine wave from −VA to + VA while rotating to °.

Next, the sensor circuit for operating the Hall element 21 which obtains such an output characteristic to take out the detection signal is formed by the circuit pattern formed on the printed board 27 and the circuit element 23 mounted on the printed board. , Figure 1
It is configured as shown in. As shown in FIG. 1, the sensor circuit is connected between the terminal T1 to which the power supply voltage Vcc is supplied from the outside and the ground terminal T4 among the four connector terminals 32, and the sensor circuit shown in FIG. The temperature compensating circuit 51 having a temperature sensitive resistor having a positive temperature characteristic for generating the reference voltage VT shown in FIG. A drive circuit 53 including an operational amplifier OP1 and a resistor R1, two amplifier circuits 55 and 57 for amplifying the voltage signal VH output from the Hall element 21, and voltage signals output from the amplifier circuits 55 and 57. The difference (V1-V2) between V1 and V2 is taken, and the difference voltage VS is used as a detection signal representing the rotation angle (that is, the throttle opening) of the rotor 5, which is one of the four connector terminals 32.
Subtraction circuit 59 that outputs from 3 to the outside, and temperature compensation circuit 5
A buffer circuit 61 for outputting the reference voltage VT having a positive temperature characteristic output from the terminal 1 as a temperature detection signal from the terminal T2 which is one of the four connector terminals 32 to the outside.
It consists of and.

Further, the amplifier circuit 55 amplifies the voltage signal VH output from the Hall element 21 as it is, and outputs it to the rotor 5
2A according to the rotation angle of the Hall element 2 and the amplifier circuit 57 is configured to output the voltage signal V1 shown in FIG.
When the voltage signal VH output from No. 1 is inverted and input, the smaller the voltage signal VH, the larger the rotation angle of the rotor 5 becomes equal to or greater than the predetermined opening θ1 and the voltage signal VH becomes saturated when the voltage signal VH exceeds a predetermined level. Then, the voltage signal V2 shown in FIG. 2A, which becomes a predetermined low level, is output.

In the throttle position sensor of this embodiment, the difference (V1−V2) between the voltage signals V1 and V2 output from the amplifier circuits 55 and 57 is calculated by the operation of the subtraction circuit 59 to determine the rotation angle of the rotor 5. Detection signal V
Since it is output as S, its detection signal VS is
As shown in (b), in the low rotation angle region where the rotation angle of the rotor 5 is θ1 or less, the change with respect to the rotation angle of the rotor 5 is large, and the rotation angle of the rotor 5 exceeds θ1 and the maximum opening θ2
In the high rotation angle region up to, the change with respect to the rotation angle of the rotor 5 has a small nonlinear characteristic.

For this reason, the throttle position sensor of this embodiment has a low opening region (0 <θ <θ
In 1), the detection sensitivity is high, and in the high opening range of the throttle valve (θ1 <θ <θ2), the detection sensitivity is low. As shown in FIG. 1, this sensor output (detection signal) VS
By directly inputting to the A / D converter 70, it is possible to obtain an A / D conversion result with high resolution in the low opening region of the throttle valve and low resolution in the high opening region of the throttle valve.

Therefore, it is not necessary to use a high resolution A / D converter in order to obtain a high resolution A / D conversion result in the low opening range of the throttle valve, unlike the conventional case.
By using one ordinary A / D converter, it is possible to obtain a high resolution A / D conversion result only in the low opening region of the throttle valve.

Further, the throttle position sensor of this embodiment is provided with a temperature compensating circuit 51 for compensating the temperature of the detection signal VS.
The reference voltage VT output from the device is output to the outside as a temperature detection signal.

Therefore, on the control device side which receives the detection signal VS from the throttle position sensor of the present embodiment and controls the engine and the like, the sensor temperature can be known from this temperature detection signal VT, and the sensor temperature or the throttle Since it is not necessary to provide another temperature sensor to detect the temperature around the valve, the configuration of the control device can be simplified.

In this embodiment, the Hall element 21 corresponds to the position detecting means of the present invention, the amplifier circuits 55 and 57 and the subtraction circuit 59 correspond to the signal processing circuit of the present invention, and the temperature compensating circuit 51 and the buffer. The circuit 61 corresponds to the temperature signal output means. Here, in the above embodiment, in order to increase the detection sensitivity in the low opening range of the throttle valve (0 <θ <θ1), the amplifier circuit 55 is used to amplify the voltage signal VH output from the hall element 21 as it is. The amplifier circuit 57,
The voltage signal VH output from the Hall element 21 is inverted and amplified to be saturated when the voltage signal VH exceeds a predetermined level. For example, the output characteristics of the amplifier circuits 55 and 57 are shown in FIG. 8B, as shown in FIG. 8B, in the low rotation angle region where the rotation angle of the rotor 5 is θ1 or less, the detection signal VS increases as the rotation angle of the rotor 5 increases.
Is gradually decreased, and in the high rotation angle region in which the rotation angle of the rotor 5 exceeds θ1 and reaches the maximum opening θ2, the detection signal VS is sharply reduced as the rotation angle of the rotor 5 increases. You can also

Further, in the above embodiment, the two amplification circuits 55 and 57 having different amplification characteristics are used to obtain the non-linear detection signal VS with respect to the rotation angle (that is, the throttle opening) of the rotor 5. However, for example, as shown in FIG. 9, n amplifier circuits A1 to An having the amplification characteristics as shown in FIG. 10A are provided in the sensor circuit, and output from each of these amplifier circuits A1 to An. Voltage signals V1 to Vn
10 by using (n-1) subtraction circuits B1 to Bn-1.
As shown in (b) and (c), if the subtraction is sequentially performed, the detection signal V as shown in FIG. 10 (d) smoothly changes with respect to the rotation angle of the rotor 5, that is, the throttle opening.
S can be obtained.

Furthermore, in the above embodiment, the amplifier circuit 5
By subtracting the voltage signals V1 and V2 output from the inverters 5 and 57 using the subtraction circuit 59, a detection signal V that is non-linear with respect to the rotation angle of the rotor 5 (that is, the throttle opening) is obtained.
Although S is obtained, an addition circuit may be used instead of the subtraction circuit 59 so that a non-linear detection signal VS with respect to the rotation angle of the rotor 5 (that is, the throttle opening) can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram illustrating a configuration of a sensor circuit according to an embodiment.

FIG. 2 is a diagram showing an amplification characteristic of an amplification circuit in the sensor circuit and an output characteristic of a detection signal from the sensor circuit.

FIG. 3 is a cross-sectional view showing the overall configuration of a throttle position sensor of the embodiment.

4 is a cross-sectional view taken along the line ABCA in FIG.

FIG. 5 is a bottom view of the throttle position sensor of the embodiment.

FIG. 6 is an explanatory diagram showing the arrangement of the hall element 21 and the permanent magnets 15 and 16 and the output characteristics of the hall element.

FIG. 7 is a diagram showing a reference voltage VT output from a temperature compensation circuit in a sensor circuit.

FIG. 8 is a diagram showing another example of amplification characteristics of an amplification circuit in a sensor circuit and output characteristics of a detection signal from the sensor circuit.

FIG. 9 is a circuit configuration diagram illustrating a configuration of a sensor circuit including n amplifier circuits.

10 is an explanatory diagram illustrating an operation of the sensor circuit illustrated in FIG. 9 and characteristics of a detection signal output from the sensor circuit.

[Explanation of symbols]

5 ... Rotor 15, 16 ... Permanent magnet 21 ... Hall element 27 ... Printed circuit board 51 ... Temperature compensation circuit 53 ...
Drive circuit 55, 57 ... Amplification circuit 59 ... Subtraction circuit 61 ... Buffer circuit 70 ... A / D converter A1 to An ... Amplification circuit B
1 to Bn ... Subtraction circuit

Front Page Continuation (72) Inventor Hitoshi Tasaka 1-1, Showa-cho, Kariya city, Aichi Nihon Denso Co., Ltd.

Claims (3)

[Claims] 1. A position detecting means for detecting a position of an object to be measured and generating a voltage signal corresponding to the detected position, and a voltage signal from the position detecting means is set in advance with respect to the detected position. A position sensor, comprising: a signal processing circuit for converting the voltage signal into a different voltage signal and outputting the voltage signal to the outside as a detection signal representing the position of the object to be measured. 2. A signal processing circuit, which has different amplification characteristics with respect to an input voltage, adds a plurality of amplification circuits for amplifying the voltage signals from the position detecting means, respectively, and adds the voltage signals amplified by the plurality of amplification circuits. The position sensor according to claim 1, further comprising: an arithmetic circuit that subtracts or. 3. The position sensor according to claim 1 or 2, further comprising temperature signal output means for detecting an ambient temperature and outputting a voltage signal according to the temperature to the outside. Position sensor to do.