JP3086553B2 - Throttle position sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throttle position sensor mounted on an internal combustion engine, and more particularly to a non-contact type throttle position sensor using a ferromagnetic element.

[0002]

2. Description of the Related Art In an internal combustion engine equipped with an electronically controlled fuel injection device, a throttle position sensor is mounted, and its output signal is used for fuel injection control and the like. This throttle position sensor is connected to a throttle valve shaft and usually has a throttle valve opening (hereinafter, referred to as a throttle valve opening).
A throttle opening signal that changes according to the throttle opening) and an idle signal that is turned on and off depending on whether the engine is in an idle region or an output region are output. With respect to such a throttle position sensor, a magnetic sensor has been used for the purpose of forming a non-contact mechanism or reducing the inertia loss of the shaft, and a magnetic sensor is provided so as to face a permanent magnet mounted on the tip of the shaft. A resistance element is provided.

As the above-mentioned magnetoresistive element, a semiconductor magnetoresistive element and a ferromagnetic magnetoresistive element are known. The former utilizes the property that the electric resistance of a semiconductor changes in a magnetic field. The latter utilizes the property that the resistance of the ferromagnetic material in a magnetic field changes anisotropically depending on the angle between the magnetization direction and the current direction. This is called an anisotropic magnetoresistive effect and is distinguished from a negative magnetoresistive effect due to the magnitude of a magnetic field. That is, in a normal ferromagnetic material, the resistance becomes the maximum when the current and the magnetization direction become parallel due to the anisotropic magnetoresistance effect, and becomes the minimum when the current and the magnetization direction cross each other. In order to make use of this effect, a ferromagnetic metal thin film is linearly adhered to the surface of the substrate to form a ferromagnetic magnetoresistive element. For example, as described in JP-A-62-237302. A rotary position detecting device in which a ferromagnetic magnetoresistive element is provided on one of an end face of a shaft and a position facing the end face and a permanent magnet is provided on the other is known.

Japanese Unexamined Patent Publication No. 2-298802 proposes a throttle position sensor that utilizes a non-contact type rotation angle sensor and can detect not only the throttle opening but also the idle range. That is, for detection of the idling region, a pattern-shaped magnetoresistive element whose longitudinal component is deviated by a predetermined angle with respect to the magnetic flux direction of the magnet member at the throttle valve closed position is used, and the magnetoresistive element near the stop position of the shaft is used. The input / output signal characteristic is set so that the output signal is linear with respect to the rotation angle of the shaft.

[0005]

The throttle position sensor is required to have a switch function, and a position detecting switch, for example, an idle switch for detecting an idle region is provided. This idle switch can be configured using a ferromagnetic magnetoresistive element. In this case, however, the ferromagnetic magnetoresistive element also has a resistance value change rate that fluctuates according to a temperature change, and has a temperature characteristic. Therefore, it is necessary to make correction in accordance with the ambient temperature when the idle region is detected. For this reason, Japanese Patent Laid-Open No. 2-29
Also in the throttle position sensor described in Japanese Patent Publication No. 8802, it is necessary to take measures such as providing a temperature compensation resistor separately, and the circuit configuration becomes complicated.

In view of the above, the present invention provides a non-contact type throttle position sensor using a ferromagnetic magnetoresistive element and a switch function that is not affected by changes in the surrounding temperature. The purpose is to be.

[0007]

In order to achieve the above object, a throttle position sensor according to the present invention comprises: a shaft which rotates in conjunction with a throttle valve; a housing which rotatably supports the shaft; A detection element having a pair of blocks whose longitudinal components are orthogonal to each other and is attached to the substrate, and a connection point between the pair of blocks as an output terminal; And a magnet member that forms a rotating magnetic field including a resistance element, such that the direction of the magnetic flux of the rotating magnetic field at the initial position forms an angle of 45 ° with respect to the longitudinal component of each block of the ferromagnetic magnetoresistive element. , One of the magnet member and the ferromagnetic magnetoresistive element is disposed at an end of the shaft, and the housing is disposed at a position facing the end. It is obtained by the placing the other stone members and said ferromagnetic magnetoresistive element.

[0008]

In the throttle position sensor having the above structure, when the shaft rotates in conjunction with the throttle valve, the magnet member rotates relative to the detecting element. In accordance with the relative rotation, the magnetic field of the parallel magnetic flux including the pair of blocks constituting the ferromagnetic magnetoresistive element of the detection element rotates, so that the resistance value of each block is increased by the anisotropic magnetoresistance effect. Change. In this case, the ferromagnetic magnetoresistive element and the magnet member have an angle of 45 ° with respect to a longitudinal component of a pair of blocks of the ferromagnetic magnetoresistive element whose magnetic flux direction at the initial position of the magnetic field is orthogonal to each other. The output characteristics of the connection point between the two blocks of the ferromagnetic magnetoresistive element at the initial position do not change due to a change in ambient temperature. Thus, the resistance value of each block of the ferromagnetic magnetoresistive element changes in accordance with the relative position change between the ferromagnetic magnetoresistive element and the magnet member, and the signal output from the connection point between the two blocks becomes the surrounding signal. The desired switch output is obtained without being affected by the temperature change.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 3 and 4 show the overall configuration of the throttle position sensor 1 according to one embodiment of the present invention, and FIG. 1 schematically shows the arrangement of the ferromagnetic magnetoresistive element 12 and the rotor magnet 20. The throttle position sensor 1 is mounted on a throttle body (not shown), and the shaft 2 is supported so as to rotate in conjunction with a throttle shaft (not shown). As shown in FIG. 3, the throttle position sensor 1 has two adjacent recesses 3a, 3b.
The shaft 2 is rotatably supported via a bearing 4 on a partition wall 3c between the recesses 3a and 3b.

A lever 5 housed in one recess 3a of the housing 3 is fixed to one end of the shaft 2.
The lever 5 is connected to a throttle shaft (not shown). A return spring 6 is interposed between the housing 3 and the lever 5, and the lever 5 is biased in a predetermined initial position direction. Therefore, with the opening operation of the throttle valve (not shown), the lever 5 linked to the throttle shaft is driven against the urging force of the return spring 6, and the shaft 2 rotates.

At the other end of the shaft 2, a rotor magnet 20, which is a magnet member according to the present invention, is fixed.
In the other concave portion 3b. The rotor magnet 20 is a rectangular permanent magnet, and is adhered to the tip of the shaft 2 as shown in FIG. The shape of the rotor magnet 20 is not limited to a rectangle, but may be a square, a circle, or the like.

The detection element 10 is arranged so as to face the rotor magnet 20. Detection element 10
Has a rectangular element substrate 11 as shown in FIG. 1, and has a ferromagnetic magnetoresistive element 12 (hereinafter simply referred to as a magnetoresistive element 1) made of a strip-shaped thin-film ferromagnetic alloy such as a Ni—Co alloy on its plate surface.
2) is attached. Note that the shape of the element substrate 11 may be a square, a circle, or the like.

The magnetoresistive element 12 is formed by bending a strip-shaped thin-film ferromagnetic alloy in order to increase the resistance and forming a pattern as shown in FIG. That is, the magnetoresistive element 12 is composed of a pair of blocks having the same shape and having a longitudinal component, and the longitudinal components of both blocks are formed in a pattern shape orthogonal to each other. Terminals 12a to 12c are formed at the ends and connection points of each block.
The constant voltage Vcc is applied to the terminal 12a, and the terminal 12b is grounded. The terminal 12c is a terminal at a connection point between the two blocks, and is connected to a non-inverting input terminal of a comparator CP shown in FIG.

The detecting element 10 is mounted on a hybrid IC board 30 (hereinafter simply referred to as IC board 30) as shown in FIGS. 3 and 4, and one end of a plurality of lead members 7 is connected to its end. . The concave portion 3b of the housing 3 is sealed by a cover 9 made of synthetic resin via a seal member 19 made of rubber. The main body of the lead member 7 is the housing 3
A connector 8 is formed integrally with the housing 3 with the other end extending sideways. It should be noted that a detection circuit element for processing the output signal of the detection element 10 and the like are mounted on the IC substrate 30, but the description is omitted because it is well known.

FIG. 2 shows a comparison circuit 13 connected to the magnetoresistive element 12. The comparator 13 has a comparator CP, and its inverting input terminal has substantially the same resistance value and substantially the same resistance temperature coefficient. The connection point of the resistor R1 and the resistor R2 is connected, a constant voltage Vcc is applied to the resistor R1,
2 is grounded (GND). Therefore, the constant voltage Vcc
Is divided by a resistor R1 and a resistor R2 having the same temperature characteristic, and a predetermined reference voltage Vi is input to the inverting input terminal of the comparator CP. The terminal 12c is connected to the non-inverting input terminal of the comparator CP, the output voltage of the terminal 12c is compared with the reference voltage Vi, and a high (H) or low (L) level voltage signal is output from the comparator CP according to the comparison result. It is configured to output from the output terminal IDL. That is,
Switching operation is performed, and an idle switch output is obtained from the output terminal IDL.

According to the throttle position sensor 1 of this embodiment, the lever 5 is driven in conjunction with the throttle valve (not shown), and the shaft 2 rotates in the bearing 4. The resistance value of each resistance Ra and Rb of the magnetoresistive element 12 changes according to the rotation of the shaft 2. That is, with the rotation of the shaft 2, the magnetic field generated by the rotor magnet 20 also rotates, and the magnetic field of the parallel magnetic flux including the magnetic field changes with respect to the magnetoresistive element 12.
Each resistance value of a and Rb changes. On the other hand, since the current is supplied to the magnetoresistive element 12 from the terminal 12a, the voltage at the terminal 12c changes as shown in FIG. 5 according to the change in the resistance value of each of the resistors Ra and Rb.

Then, in the comparator CP, the terminal 1
2c is compared with a reference voltage Vi, and this reference voltage V
When the value is i or more, the output of the comparator CP, that is, the output of the output terminal IDL is a low (L) level output as shown in FIG. When the voltage falls below the reference voltage Vi, the output of the comparator CP goes high (H), and is output from the output terminal IDL as an idle signal indicating that the throttle valve is in an idle range. In other words, the reference voltage V
An idle (H) or off (L) idle switch output is obtained according to the result of comparison with i.

In this case, the direction of the magnetic flux of the magnetic field by the rotor magnet 20 as the magnet member is
Are in a positional relationship of 45 ° with respect to the longitudinal component of each block, the total resistance of the resistors Ra and Rb changes due to a change in ambient temperature, but the resistances are equal. Does not change with changes in ambient temperature. Therefore, as shown in FIG. 5, by setting the above position to the throttle opening of 0 ° and setting the output value at this position as the threshold level to set the reference voltage Vi, the temperature characteristic of the magnetoresistive element 12 is affected. The idling range can be distinguished without the need.

As described above, in the present embodiment, the magnetoresistive element 12 is located at a position where the longitudinal components of the two blocks make an angle of 45 ° with the magnetic field of the rotor magnet 20, that is, the output fluctuation due to the temperature change. Is located at a position where no noise occurs, it is possible to suppress a detection error in an idle region due to a change in ambient temperature. Therefore, stable detection accuracy can be ensured even in a severe external environment.

FIG. 6 shows another embodiment of the throttle position sensor according to the present invention, in which a magnetoresistive element 14 having the same function as the idling area detecting magnetoresistive element 12 of the above-described embodiment is opened. It is formed on the same element substrate 11 as the magnetoresistive element 15 for detecting the degree, that is, the rotation angle. In this case, the rotor magnet 20 is arranged such that the initial position is indicated by a two-dot chain line. The other configuration is the same as that of the above-described embodiment.
The configuration of No. 5 is the same as the conventional one, and therefore the description is omitted.

The magnetoresistive element 14 of this embodiment is formed such that the longitudinal components of both blocks form an angle of 45 ° with the longitudinal components of each block of the magnetoresistive element 15. The longitudinal components of both blocks of the resistance element 14 are orthogonal to each other and form an angle of 45 ° with respect to the magnetic field at the initial position of the rotor magnet 20, which is substantially the same as that of the magnetoresistance element 12 of the above-described embodiment. And has a similar effect. Further, when a bias magnet (not shown) is additionally provided in addition to the above configuration, the magnetoresistive element 14 may be arranged so as to form an angle of 45 ° with the direction of the magnetic field at the initial position of the rotor magnet 20. .

[0022]

Since the present invention is configured as described above, the following effects can be obtained. That is, according to the throttle position sensor of the present invention, the direction of the magnetic flux at the initial position of the magnetic field of the magnet member forms an angle of 45 ° with respect to the mutually orthogonal longitudinal components of both blocks of the ferromagnetic magnetoresistive element. Since the output characteristics of the ferromagnetic magnetoresistive element at the initial position do not change due to a temperature change, a signal is output from the detecting element according to a change in the relative position between the ferromagnetic magnetoresistive element and the magnet member. As a result, it is possible to secure an appropriate switch function that is not affected by the temperature change, and it is possible to appropriately detect the idle region without being affected by the ambient temperature change.

[Brief description of the drawings]

FIG. 1 is a plan view showing an arrangement of a ferromagnetic magnetoresistive element and a rotor magnet housed in a throttle position sensor according to one embodiment of the present invention.

FIG. 2 is a circuit diagram of a comparison circuit used in a throttle position sensor according to one embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of a throttle position sensor according to one embodiment of the present invention.

FIG. 4 is a plan view of the throttle position sensor according to the embodiment of the present invention with a cover removed.

FIG. 5 is an output characteristic diagram of a throttle position sensor according to one embodiment of the present invention.

FIG. 6 is a plan view showing an arrangement of a ferromagnetic magnetoresistive element and a rotor magnet housed in a throttle position sensor according to another embodiment of the present invention.

[Explanation of symbols]

 2 Shaft 3 Housing 10 Detecting element 11 Element substrate 12 Ferromagnetic magnetoresistive element 20 Rotor magnet (magnet member)

Claims (1)

(57) [Claims] 1. A ferromagnetic magnetoresistive element comprising: a shaft rotating in conjunction with a throttle valve; a housing rotatably supporting the shaft; and a pair of blocks housed in the housing and having longitudinal components orthogonal to each other. A detection element having an element attached to a substrate and having a connection point between the pair of blocks as an output terminal, and a magnet member for forming a rotating magnetic field including at least the ferromagnetic magnetoresistance element; Either the magnet member or the ferromagnetic magnetoresistive element is connected to the end of the shaft so that the direction of the magnetic flux of the rotating magnetic field at the initial position forms an angle of 45 ° with the longitudinal component of each block of the element. Wherein the other of the magnet member and the ferromagnetic magnetoresistive element is disposed in the housing at a position facing the end. Yonsensa.