JPH02298802A - Throttle position sensor - Google Patents

Abstract

PURPOSE:To enable easy detection of an idle area by a method wherein a pattern-shaped magnetoresistance element of which a component in the longitudinal direction is biased by a prescribed angle from the magnetic flux of a magnet at a position of closure of a valve is provided on a base. CONSTITUTION:A magnet member 20 located at the fore end of a shaft 2 rotating in gearing with a throttle valve is provided rotatably opposite to a magnetic sensor 10. The magnetic sensor 10 is provided with a first magnetoresistance element 12 and also a second magnetoresistance element 13 which is shaped in a pattern and of which a component in the longitudinal direction is biased by a prescribed angle alpha from the magnetic flux of a magnet 21 at the time when the valve is at a position of closure. In this constitution, a voltage being proportional to the degree of opening of a throttle is obtained from the resistance element 12, while input and output signals out of which an output signal is linear to the angle of rotation of the shaft are obtained in the vicinity of a position of stop of the shaft 2 from the resistance element 13. Therefore, an idle area is distinguished sharply and can be detected reliably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a throttle position sensor installed in an internal combustion engine, and particularly to a throttle position sensor using a magnetic sensor.

[Prior art] In an internal combustion engine equipped with an electronically controlled fuel injection device,
A throttle position sensor is installed, and its output signal is used for fuel injection control. This throttle position sensor is connected to the throttle valve shaft, and normally outputs a throttle opening signal that changes depending on the throttle valve opening (hereinafter referred to as throttle opening) and an idle signal that turns on and off depending on whether it is in the idle range or output range. be done.

The former throttle opening signal is sometimes referred to as an on/off signal that is output according to the throttle opening, but it was
As described in Japanese Utility Model Application No. 41708, Japanese Utility Model Application No. 59-115304, or Japanese Utility Model Application No. 62-81004, an analog voltage output proportional to the throttle opening is generally used. For this reason, the throttle position sensor includes a potentiometer that is linked to the throttle valve as described in the above-mentioned publication. That is, the movable contact slides on the resistor in response to the closing operation of the throttle valve, and a voltage between one end of the resistor and the movable contact is output. Further, when the throttle valve is closed, another movable contact interlocked with the throttle valve closes the normally open idle signal fixed contacts, and an on signal indicating the idle range is output.

[Problems to be Solved by the Invention] Since a potentiometer is used in the above-mentioned conventional throttle position sensor, sliding movement between the resistor and the movable contact brush is essential, and the mechanical contact relationship between the two is essential. It is basic. Therefore, it is necessary to take various measures against problems caused by mechanical contact, such as wear of brushes or resistors. As a solution to this problem, the use of a non-contact rotation angle sensor is effective and can be used relatively easily to detect the throttle opening, but it is not easy to detect the idle range and requires a separate switch means etc. The significance of adopting a contactless model will be diminished. for example,
When a magnetic sensor having a magnetoresistive element is used, it is difficult to set an accurate threshold level because the output changes slowly in a region where the throttle opening, that is, the rotation angle is small.

Therefore, an object of the present invention is to use a non-contact rotation angle sensor having a magnetic sensor as a throttle position sensor, and to easily detect not only the throttle opening but also the idle range.

[Means for Solving the Problems] In order to achieve the above object, the throttle position sensor of the present invention includes a shaft that rotates in conjunction with a throttle valve, a housing that rotatably supports the shaft, and a shaft that rotates in a predetermined direction. a magnet member that forms a magnetic field having a parallel magnetic flux; and a detection element that faces the magnet member and is housed in the housing, the detection element having a longitudinal component with respect to the magnetic flux direction of the magnet member in the closed position of the throttle valve. a detection element formed by attaching a pattern-shaped magnetoresistive element deviated at a predetermined angle to a plate surface of a substrate, one of the detection element and the magnet member is attached to one end of the shaft, and the other is attached to the housing. It is fixed at a predetermined position opposite to one end of the shaft inside.

Further, the throttle position sensor of the present invention includes a shaft that rotates in conjunction with a throttle valve, a housing that rotatably supports the shaft, and a detection element housed in the housing. a detection element comprising a first magnetoresistive element having a predetermined pattern shape and a second magnetoresistive element having a pattern shape offset at a predetermined angle with respect to the pattern shape of the first magnetoresistive element; a magnet member facing the detection element, one of the magnet member and the detection element is attached to one end of the shaft, and the other is fixed at a predetermined position facing the one end of the shaft within the housing. You can also use it as

The magnet member preferably has a pair of magnetic poles facing each other on both sides of the substrate, and forms a magnetic field that includes at least the plate surface of the substrate.

[Operation] In the throttle position sensor configured as described above, a detection element having a magnetoresistive element in a predetermined pattern shape is used for detecting the idle region where the throttle valve is substantially in the closed position. In other words, since the longitudinal component of the magnetoresistive element is deviated by a predetermined angle with respect to the direction of the magnetic flux of the magnet member at the throttle valve closed position, the output signal of the magnetoresistive element changes to the rotation angle of the shaft near the shaft stop position. Input/output signal characteristics can be set so as to be linear with respect to the input/output signal. Thereby, the idle region within the predetermined throttle opening range is clearly distinguished and detected reliably.

In addition, in a device equipped with the first and second magnetoresistive elements, the first magnetoresistive element is used as a rotation angle sensor that detects the rotation angle of the shaft that rotates in accordance with rotation of the throttle valve. , a second magnetoresistive element is used for idle range detection. Thus, the throttle opening degree is detected as an output signal of the first magnetoresistive element, and whether or not the throttle valve is in an idle state is detected as an output signal of the second magnetoresistive element. At this time, the second
Since the magnetoresistive element is offset by a predetermined angle with respect to the first magnetoresistive element, the output signal of the second magnetoresistive element is linear with respect to the rotation angle of the shaft near the stop position of the shaft. Input and output signal characteristics can be set. This ensures that the idle area is detected.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

1 to 3 relate to an embodiment of a magnetic sensor used in the throttle position sensor of the present invention, and FIG. 1 shows first and second ferromagnetic magnetoresistive elements 12 constituting a magnetic sensor 10 .13 (hereinafter simply referred to as first and second magnetoresistive elements 12°13).

The first magnetoresistive element 12 is a strip-shaped N
A thin film ferromagnetic alloy such as an i-Co alloy is bent and formed into a pattern as shown in FIG. That is, blocks centered on elements whose longitudinal directions are horizontal and blocks whose centers are centered on elements whose longitudinal directions are vertical are alternately connected to form four blocks. Terminals 12a to 12d are formed at connection points between each block. Terminals 12a and 12b are so-called current terminals, and terminal 12a is connected to the power supply V.
c, and the terminal 12b is grounded. terminal 12
C and 12d are so-called voltage terminals, from which detection signals are output.

The second magnetoresistive element 13 constitutes a pattern-shaped magnetoresistive element in which the longitudinal component is deviated at a predetermined angle with respect to the magnetic flux direction according to the present invention, and is made of the same material as the first magnetoresistive element 12 in the horizontal direction. A pattern shape is formed in which blocks forming an angle α with respect to the vertical direction and blocks forming an angle α with respect to the vertical direction are connected. The second magnetoresistive element 13 is offset by an angle α with respect to the pattern of the first magnetoresistive element 12, as shown in FIG. It is preferable that this angle α is around 40°, avoiding 45°.
b is a current terminal, terminal 13a is connected to power supply Vc, and terminal 13b is grounded. Terminal 13c is a voltage terminal, from which a detection signal is output. The second magnetoresistive element 13 is connected to the operational amplifier oP together with resistors R1 and R2 to form a comparison circuit, as shown in FIG.

Thus, the first magnetoresistive element 12 is used for detecting the throttle opening, and the second magnetoresistive element is used for detecting the idle range. As shown in FIG.
Terminals 12a to 12d and terminals 13a to 13c are mounted on a plurality of leads 31 printed on a circuit board 30.
is connected.

A magnet member 20 is placed opposite the magnetic sensor 10 with a predetermined gap therebetween as shown in FIG. The magnet member 20 consists of a permanent magnet 21 and a pair of magnetic arms 22, 2°3 having an abbreviated cross-section, which are joined to both sides of the permanent magnet 21. 2 is fixed to a permanent magnet 21. Magnetic arm 22
, 23 are bonded to the side surfaces of the permanent magnet 21 by adhesive or the like so that the end surfaces of the tip portions 22a, 23a of each bending portion face each other, and a gap is formed between the end surfaces of the tip portions 22a, 23a. Thus, the permanent magnet 21 causes the magnetic arm 2 to
N8i, S&
is formed, and a magnetic field of parallel magnetic flux with uniform magnetic flux density is formed between the two.

The magnetic sensor 10 and magnet member 20 are shown in FIGS. 4 and 5.
As shown in the figure, it is housed within a throttle position sensor 1. The throttle position sensor 1 is attached to a throttle body (not shown), and is supported so that the shaft 2 rotates in conjunction with a throttle shaft (not shown). That is, the throttle position sensor 1 includes a synthetic resin housing 3 having two adjacent recesses 3a and 3b, and a partition wall 3C between these recesses 3a and 3b.
A shaft 2 is rotatably supported via a bearing 4.

A lever 5 housed in one recess 3a of the housing 3 is fixed to one end of the shaft 2, and 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 urged toward a predetermined initial position, that is, toward a closed position of a throttle valve (not shown).

Therefore, as the throttle valve opens, the lever 5 that is linked to the throttle shaft is moved to the return spring 6.
The shaft 2 is configured to rotate by being driven against the urging force of the shaft 2. Note that although a sintered oil-impregnated bearing is used as the bearing 4 in this embodiment, it goes without saying that a ball bearing or the like may also be used.

A magnet member 20 is fixed to the other end of the shaft 2 and housed in the other recess 3b of the housing 3. and,
The magnetic sensor 10 is disposed so as to face the permanent magnet 21 constituting the magnet member 20 and to be located between the magnetic arms 22 and 23 at both ends thereof. A plurality of terminals 32 and a plurality of board members 7 are connected to a circuit board 30 on which these magnetic sensors 10 are mounted. The lead member 7 is embedded in the housing 3 and extends laterally to the housing 3.
A connector 8 is formed integrally with the connector. The circuit board 30 is housed and fixed in a recess 3b of the housing 3, and the recess 3b is sealed with a cover 9 made of synthetic resin.

In other words, according to the throttle position sensor 1 of this embodiment, the lever 5 shown in FIG. 4 is driven in conjunction with a throttle valve (not shown), and the shaft 2 rotates within the bearing 4. The first magnetoresistive element 1 responds to the rotation of the shaft 2.
The resistance value of 2 changes. In the first magnetoresistive element 12, a bridge circuit is formed by each block between the terminals 12a and 12a, and a constant current is supplied to this bridge circuit. Therefore, the output voltages of the terminals 12c and 12d change according to changes in the resistance value of each block of the first magnetoresistive element 12, and a voltage output as a throttle opening signal is obtained through a differential amplifier circuit (not shown).

That is, the first magnetoresistive element 12 has magnetic arms 22 and 23.
The plate and surface of the element substrate 11 are located parallel to this in a uniform parallel magnetic field formed between the tip portions 22a and 23a, and therefore the first magnetoresistive element 12 has a magnetic field parallel to the plate surface. Uniform magnetic flux is provided. When the permanent magnet 21 rotates around the magnetic sensor 10 due to the rotation of the shaft 2, the magnetic field between the tips 22a and 23a rotates, and the angle between the magnetization direction and the current direction with respect to the first magnetoresistive element 12 changes. . In this case, the current supplied to the first magnetoresistive element 12 and the tip 22a.

When the magnetization direction due to the magnetic field between 23a becomes parallel, the first
The resistance value of the magnetoresistive element 12 becomes maximum and becomes minimum when they are perpendicular to each other. As a result, the outputs of the terminals 12c and 12d become substantially sinusoidal waves, and an output characteristic that is substantially linear with respect to the rotation angle of the shaft 2 is obtained except for the vicinity of the maximum and minimum values.

In the operation of the throttle position sensor, if the shaft 2 is displaced in the axial direction due to the support structure of the shaft 2 or displaced in a direction parallel to the magnetic sensor 10 due to misalignment, the magnetic member 20 sensor 1
Although the tip portions 22a and 23 will be displaced relative to 0,
The magnetic field formed between a is a uniform parallel magnetic flux, so the first
The magnetic flux applied to the magnetoresistive element 12 does not change. Therefore, a stable voltage signal is output from the terminals 12c and 12d without being affected by the displacement of the shaft 2.

In addition, according to the rotation of the shaft 2, the N2 of the magnetic sensor 10 is
The resistance value of the magnetoresistive element 13 changes. That is, when the magnetic arms 22 and 23 of the magnet member 20 are in the initial position, a magnetic field of parallel magnetic flux including the second magnetoresistive element 13 is applied in the horizontal direction in FIG. 1. Therefore, the output voltage at the terminal 13c of the second magnetoresistive element 13 is below the threshold level determined by the resistors R1 and R2 in FIG. 6, as shown in FIG.

As the shaft 2 rotates, the magnetic arm 22.2
3 also rotates, the output voltage of the terminal 13c increases linearly, and when the rotation angle of the shaft 2 reaches a predetermined angle, it exceeds the above threshold level.

The potential of the terminal 13c in FIG. 6 changes as shown in FIG. 7(b), and the output shown in FIG. 7(a) is obtained from the operational amplifier oP based on the threshold level. As a result, the throttle opening range indicated by α in FIG. 7 is sharply divided into an idle range. On the other hand, as shown in FIG. 8, which shows the input/output characteristics when the idle region is detected using the output voltage of the first magnetoresistive element 12, when the second magnetoresistive element 13 is not used, The output voltage near the throttle opening in the idle range is not clearly distinguished from the threshold level, and therefore the throttle opening range α over which the idle range signal is output becomes unstable.

As described above, according to this embodiment, the first magnetoresistive element 1
2, the throttle opening degree is detected, and at the same time, the second magnetoresistive element 13 reliably detects the idle range.

[Effects of the Invention] Since the present invention is configured as described above, it produces the effects described below.

That is, in the throttle position sensor of the present invention, the magnet member is configured to rotate relative to the detection element, and the detection element has a longitudinal component that is deviated by a predetermined angle with respect to the magnetic flux direction at the throttle valve closed position. Since the input/output characteristics can be easily distinguished from the threshold level, the idle range of the throttle valve can be detected with high accuracy.

In the case of using a detection element including the first and second magnetoresistive elements, the throttle opening degree can be simultaneously detected with high precision, resulting in a reduction in the number of parts.

In addition, if the magnet member has a pair of magnetic poles facing both sides of the substrate of the detection element, a magnetic field is formed that includes the plate surface of the substrate, and the magnetoresistive element attached to the substrate is constantly exposed to a uniform magnetic field. Therefore, even if the shaft is displaced in the axial direction or in the direction parallel to the substrate, the output of the detection element does not change, and stable detection accuracy can be ensured.

[Brief Description of the Drawings] Fig. 1 is a plan view of a magnetic detection element constituting a magnetic sensor housed in a throttle position sensor according to an embodiment of the present invention, and Fig. 2 is a circuit in which the magnetic sensor is mounted. Figure 3 is a plan view of the board, Figure 3 is a perspective view of the magnetic sensor and magnet member, Figure 4 is a longitudinal sectional view of the throttle position sensor, and Figure 5 is the same, with the throttle position sensor cover removed. flat. - Figure 6 is the same circuit diagram for detecting the idle range, 11' Figure 7 (a) is the characteristic diagram of the idle range signal, Figure i7 (b) is the magnetic resistance element for detecting the idle range. Figure 8 (a) is a characteristic diagram of the idle range signal when the magnetoresistive element for throttle opening detection is used for idle range detection, and Figure 8 (b) is the input/output characteristic diagram for throttle opening detection. It is a human output characteristic diagram of a magnetoresistive element. 1... Throttle position sensor. 2...shaft, 3...housing. 10... Magnetic sensor (detection element). 11... Element substrate, 12... First magnetoresistive element. 13...Second magnetoresistive element. 20... Magnet member, 21... Permanent magnet. 22.23...Magnetic arm. 22a, 23a...Tip portion, 30...Circuit board.

Claims (3)

[Claims] (1) A shaft that rotates in conjunction with a throttle valve, a housing that rotatably supports the shaft, a magnet member that forms a magnetic field having parallel magnetic flux in a predetermined direction, and a magnet member that is located inside the housing and that faces the magnet member. a detection element housed in the throttle valve, the detection element comprising 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 in the closed position of the throttle valve, and which is attached to the plate surface of the substrate. a throttle position sensor, characterized in that either the detection element or the magnet member is attached to one end of the shaft, and the other is fixed at a predetermined position in the housing opposite to the one end of the shaft. . (2) A shaft that rotates in conjunction with the throttle valve, a housing that rotatably supports the shaft, and a detection element housed in the housing, the detection element having a predetermined pattern shape on the plate surface of the substrate. a detection element having a magnetoresistive element attached thereto and a second magnetoresistive element having a pattern shape deviated at a predetermined angle with respect to the pattern shape of the first magnetoresistive element; and a magnet facing the detection element. A throttle position sensor comprising a member, wherein one of the magnet member and the detection element is attached to one end of the shaft, and the other is fixed at a predetermined position in the housing opposite to the one end of the shaft. . (3) The throttle according to claim 1 or 2, wherein the magnet member has a pair of magnetic poles facing each other on both sides of the substrate, and forms a magnetic field that includes at least a plate surface of the substrate. position sensor.