JP2015105872A - Rotation angle detection sensor and throttle device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation angle detection sensor capable of achieving the reduction in cost.SOLUTION: A rotation angle detection sensor 1 includes: a rotor 20 rotationally moving by receiving external force; a sensor element 31 in which characteristic change is generated by strain generated on the basis of the rotational motion; and a cam projection 23 for converting the rotational motion of the rotor 20 into the strain. The rotor 20 rotationally moves, so that the cam projection 23 generates the characteristic change in the sensor element 31 on the basis of the rotational motion. A rotation angle θ of the rotor 20 is identified by detecting the characteristic change.

Description

  The present invention relates to a rotation angle detection sensor, and more particularly to a sensor that detects rotation angles of various members.

  Various sensors are used to detect the rotation angle. For example, a Hall sensor applies a magnetic field horizontal to the surface of a sensor chip provided with a magnetoelectric conversion element by a permanent magnet, and detects an absolute angle around the rotation axis of the permanent magnet (for example, Patent Document 1). The resolver has a stator and a rotor, and detects according to the rotation angle of the rotor with respect to the stator by utilizing the fact that the mutual inductance between the stator and the rotor changes depending on the rotation position of the rotor with respect to the stator. A signal is output (for example, Patent Document 2). In addition, MR sensors, optical encoders, potentiometers, and the like are also known.

  There are many applications for detecting the rotation angle, and a sensor suitable for the application is selected in consideration of factors such as detection accuracy, reliability, and cost. For example, in an electronically controlled fuel injection system (Fuel Injection System) used in an internal combustion engine that is the driving source of automobiles (four-wheels) and motorcycles, the rotation angle of the throttle valve (Throttle Valve) Hall sensors and potentiometers are mainly applied to the sensors to be detected.

JP 2013-2835 A JP 2010-239893 A

Since the FI system can control the air-fuel ratio with high accuracy, it is combined with the exhaust gas purification effect due to the synergistic effect with the catalyst, leading to the introduction to automobiles and large motorcycles, and then a small two-wheeled vehicle including a motorbike. The application of the FI system is also progressing. However, since small motorcycles have lower vehicle prices than automobiles and large / medium-sized motorcycles, it is necessary to reduce the cost of the FI system even if environmental effectiveness is considered. In particular, when a motor-equipped bicycle is an application target, there is a great demand for cost reduction.
Speaking of the sensor that detects the rotation angle of the throttle valve, which is a component of the FI system, the Hall sensor and potentiometer are lower in cost than the MR sensor and optical encoder, but are even lower in cost when a small motorcycle is assumed. Is required.
The present invention has been made based on such a background, and an object of the present invention is to provide a rotation angle detection sensor that can realize cost reduction.
Another object of the present invention is to provide a throttle device for an internal combustion engine including such a rotation angle detection sensor.

For this purpose, the rotational angle detection sensor according to the present invention includes a rotor that rotates in response to an external force, a sensor element that changes in characteristics due to a strain generated based on the rotational motion, and a rotational motion of the rotor. And a cam member for conversion.
In the rotation angle detection sensor of the present invention, when the rotor receives a force and rotates, the cam member causes a change in characteristics of the sensor element based on the rotation. Since the characteristic change fluctuates in accordance with the rotation angle of the rotor, the rotation angle of the rotor can be specified by detecting the characteristic change.

In the rotation angle detection sensor of the present invention, the cam member is preferably provided integrally with the rotor.
By providing the cam member integrally with the rotor, the cam member can be rotated together with the rotor.

Moreover, a strain gauge can be used for the sensor element of the rotation angle detection sensor of the present invention.
By using a strain gauge for the sensor element, it is possible to capture the rotational displacement of the cam member due to the rotation as a variation in strain. Furthermore, since a strain gauge is inexpensive, a rotation angle detection sensor can be produced at low cost by using it as a sensor element.

  The present invention also provides a throttle device for an internal combustion engine including the rotation angle detection sensor.

  According to the present invention, the sensor element that causes a change in characteristics by the rotating rotor and the cam member is a main component, so that a rotation angle detection sensor that can reduce the cost is provided.

It is a figure which shows the rotation angle detection sensor in this Embodiment. It is a figure which shows operation | movement of the cam member of FIG. It is a graph which shows the correlation data regarding the change of the voltage of a rotation angle detection sensor. It is a figure which shows the example which applies the rotation angle detection sensor of FIG. 1 to the detection of the opening degree of the throttle valve of FI system.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
As shown in FIG. 1, the rotation angle detection sensor 1 according to this embodiment is provided in a stator 10 including a detection unit 11 and a support unit 16, a rotor 20 supported by the support unit 16, and the detection unit 11. And a detection unit 30 having a sensor element 31 in which a characteristic change occurs based on the rotation of the rotor 20.

[Stator 10]
The stator 10 includes a detection unit 11 and a support unit 16. In the following description, the side on which the detection unit 11 is provided is defined as the upper side.
The detection unit 11 includes a detection chamber 13 separated from the outside by a shell 12. A support column 14 is built in the detection chamber 13, and one end of a holding plate 15 is fixed to the side surface thereof.
The plane of the holding plate 15 is fixed along the vertical direction. The holding plate 15 is provided with elasticity that can be flexed without difficulty when a cam projection 23 described later is pressed.
The support portion 16 has a support hole 17 penetrating in the axial direction. The rotor 20 is rotatably supported in the support hole 17. In the rotor 20, a pair of flanges 18 sandwich the support portion 16, and displacement in the axial direction is restricted.

[Rotor 20]
The rotor 20 is a member in which a cam projection 23 is integrally formed at the tip. A portion excluding the cam projection 23 has a cylindrical shape, and a lever 25 is provided at a lower end.
When the rotor 20 receives an external force and rotates, the cam protrusion 23 is pressed against the holding plate 15 to bend the holding plate 15. Hereinafter, the direction in which the holding plate 15 bends is defined as the front. The lever 25 is operated when rotating the rotor 20. The rotor 20 rotates counterclockwise when the lever 25 rotates counterclockwise (hereinafter sometimes referred to as forward rotation), and conversely rotates when the lever 25 rotates clockwise.
The cam protrusion 23 includes a start point 23s and an end point 23e. The line segment connecting the start point 23s and the center C and the line segment connecting the end point 23e and the center C are orthogonal to each other. As will be described later, the cam projections 23 flex the holding plate 15 by continuously contacting the back surface 15b of the holding plate 15 from the start point 23s to the end point 23e as the rotor 20 rotates.

[Detection unit 30]
The detection unit 30 includes a sensor element 31 provided on the holding plate 15 of the stator 10 and a detector 33 that detects a change in characteristics of the sensor element. The sensor element 31 is electrically connected to a detector 33 disposed outside the stator 10.
The sensor element 31 is fixed to the front surface 15a of the holding plate 15, and stress is generated according to the bending of the holding plate 15. In the present embodiment, the sensor element 31 uses a strain gauge.
As the strain gauge, for example, a foil strain gauge including a thin electric insulator and a metal resistor formed by etching on the electric insulator and continuously meandering can be used. When this metal resistor is distorted, the electrical resistance value changes, so if a voltage is detected while a current is passed through the metal resistor, it can be detected whether or not the metal resistor is distorted from the change. Can do. As the strain gauge, a foil strain gauge, a wire strain gauge, a semiconductor strain gauge, or the like can be used.
The position where the sensor element 31 is provided is not particularly limited, but it is preferable to provide the sensor element 31 in a region where the deflection of the holding plate 15 based on the rotation of the rotor 20 is large in order to obtain high detection sensitivity.

The detector 33 supplies a current to the sensor element 31 and detects the voltage V of the sensor element 31.
The detector 33 holds correlation data regarding the rotation angle θ corresponding to the voltage V. For the correlation data, the rotation angle detection sensor 1 is used to measure the voltage V corresponding to each rotation angle θ each time the lever 25 is rotated by a predetermined angle, for example, 0 degree, 1 degree, 2 degrees, etc. You can get it. FIG. 3 shows an example in which the rotation angle θ and the voltage V are in a proportional relationship. However, this is only an example.
The detector 33 specifies the rotation angle θ of the lever 25 (rotor 20) by comparing the detected voltage V with the correlation data.

The operation of the rotation angle detection sensor 1 configured as described above will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1B, the rotation angle θ is set to 0 degree when the starting point 23s of the cam projection 23 is arranged to be a contact point on the back surface 15b without applying a load to the holding plate 15. Has been. By arranging in this way, the degree of bending of the holding plate 15, that is, the voltage V can be specified when the rotation angle θ of the rotor 20 is in the range of 0 to 90 degrees.
When the lever 25 is rotated forward, the cam protrusion 23 is also rotated forward in synchronization. Then, as shown in FIG. 2A, the cam projection 23 deflects the holding plate 15 forward, and the sensor element 31 is distorted. At this time, the cam projection 23 converts the rotational motion of the rotor 20 into the strain of the sensor element 31. When the sensor element 31 is distorted, the electric resistance value of the metal resistor changes, so that the detector 33 detects the voltage Va corresponding to the changed electric resistance value.
When the lever 25 is further rotated forward, the cam protrusion 23 is rotated forward as shown in FIG. The detector 33 further detects a voltage Vb (Vb> Va) corresponding to the changed electric resistance value.
The detector 33 can identify the rotation angles θa and θb of the lever 25 by collating the detected voltages Va and Vb with the correlation data.

[Application example]
As one of the uses of the rotation angle detection sensor 1 of this embodiment, it can be used to detect the rotation angle of a throttle valve that is a component of the FI system.
FIG. 4 shows a schematic configuration. The throttle valve 40 is a butterfly valve, and the valve body 43 opens and closes a flow path provided in a valve box (not shown) by rotating the valve shaft 41 by 90 degrees. The valve shaft 41 is connected to an electric actuator 45, and the electric actuator 45 opens and closes the valve body 43 via the valve shaft 41 by a control signal given from an ECU (Engine Control Unit) 35. The ECU 35 controls the opening degree of the valve body 43 to supply an optimal amount of air-fuel mixture including fuel injected from an injector (Engine Control Unit) (not shown) into the cylinder of the engine. As a premise for controlling the valve body 43, the ECU 35 needs to continuously recognize the opening degree of the valve body 43. The rotation angle detection sensor 1 is used to detect the opening degree of the valve body 43. The ECU 35 also has the function of the detector 33 shown in FIG.

  In the rotation angle detection sensor 1, the rotor 20 is connected to the valve shaft. At this time, the shaft of the rotor 20 is connected so as to coincide with the valve shaft 41. Therefore, when the valve shaft 41 is driven by the electric actuator 45, the rotor 20 rotates following the valve shaft 41. When the rotor 20 rotates, the cam protrusion 23 rotates accordingly, and the degree of distortion of the sensor element 31 changes. Therefore, the ECU 35 can detect the rotation angle θ of the lever 25, that is, the opening degree of the valve body 43 based on the voltage V. The ECU 35 sends a control signal to the electric actuator 45 while referring to the detected opening of the valve body 43.

Although the present embodiment has been described above, the configuration described in the above embodiment can be selected or changed to other configurations as appropriate without departing from the spirit of the present invention. is there.
The present invention is not limited to the present embodiment as long as the cam protrusion 23 causes the sensor element 31 to change its characteristics as the rotor 20 rotates. For example, even if the cam projection 23 is provided on the support column 14 and the holding plate 15 provided with the sensor element 31 is provided on the rotor 20, the same effect can be obtained.
In the present invention, the characteristics of the sensor element 31 may be changed by the cam protrusion 23. Therefore, the sensor element 31 can be provided not on the holding plate 15 but on the cam protrusion 23. In this case, since the cam projection 23 is loaded with a reaction force corresponding to the stress applied to the holding plate 15 by the rotation of the rotor 20, the sensor element 31 can be distorted.

  In the present embodiment, a strain gauge has been described as an example of the sensor element 31, but as another element whose characteristics change due to strain, for example, a piezoelectric element that outputs a voltage corresponding to the pressure received by the strain is used as the sensor element. You can also.

  In the present embodiment, the sensor element 31 is provided on the holding plate 15 fixed to the support column 14. However, as long as the characteristics of the sensor element are changed by the cam protrusion 23, the position where the sensor element 31 of the present invention is provided is not limited. . For example, even if the sensor element 31 is fixed to the shell 12 of the stator 10 and the cam protrusion 23 of the rotor 20 is pressed against the shell 12, the characteristics of the sensor element 31 can be changed. However, as in the present embodiment, if a support column 14 independent of the shell 12 is built in the detection chamber 13 and the holding plate 15 provided with the sensor element 31 is fixed to the support column 14, an external force is temporarily applied to the shell 12. Even if acted, the detection result by the sensor element 31 is hardly affected by the external force.

  In the present embodiment, the detection chamber 13 isolated by the shell 12 is provided in the stator 10, and the main element for detection including the sensor element 31 is accommodated therein. However, the present invention does not necessarily provide the isolated detection chamber 13 and can detect the rotation angle even if the main element for detection is exposed. However, the main element can be protected by accommodating it in the isolated detection chamber 13.

DESCRIPTION OF SYMBOLS 1 Rotation angle detection sensor 10 Fixed body 11 Detection part 12 Shell 13 Detection chamber 14 Support | pillar 15 Holding plate 15a Front surface 15b Back surface 16 Support part 17 Support hole 18 Flange 20 Rotor 23 Cam protrusion 23s Start point 23e End point 25 Lever 30 Detector 31 Sensor element 33 Detector 35 ECU
40 Throttle valve 41 Valve shaft 43 Valve body 45 Electric actuator θ Rotation angle V Voltage C Center

Claims (4)

A rotor that rotates in response to an external force;
A sensor element in which a characteristic change is caused by strain generated based on the rotational motion;
A cam member that converts the rotational movement of the rotor into the strain;
A rotation angle detection sensor comprising: The cam member is provided integrally with the rotor;
The rotation angle detection sensor according to claim 1. The sensor element comprises a strain gauge;
The rotation angle detection sensor according to claim 1 or 2. A throttle valve for controlling the supply amount of the air-fuel mixture in the internal combustion engine;
A rotation angle detection sensor that detects an opening of the throttle valve as a rotation angle,
The said rotation angle detection sensor is a rotation angle detection sensor as described in any one of Claims 1-3, The throttle device of the internal combustion engine characterized by the above-mentioned.

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