JP2015105871A - 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 includes: a pair of screw elements engaging with each other; a displacement mechanism in which one screw element is displaced if the other rotates by receiving external force; and a sensor element in which characteristic change is generated on the basis of the displacement. The pair of screw elements and the sensor element are the main components, so that the rotation angle detection sensor can achieve the reduction in cost.

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 rotation angle detection sensor according to the present invention includes a pair of screw elements that mesh with each other, and when any one of the screw elements is rotated by receiving an external force, any one of the screw elements is displaced in the axial direction. It is characterized by comprising a displacement mechanism and a sensor element that causes a characteristic change based on the displacement.
When any one of the pair of screw elements rotates, any one of the screw elements is displaced, so that a characteristic change can be caused in the sensor element based on the displacement. Therefore, since the characteristic change fluctuates corresponding to the rotation angle of the screw element, the rotation angle of the screw element can be specified by detecting the characteristic change.

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, the displacement of the screw element due to rotation can be understood 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.

Further, in the rotation angle detection sensor of the present invention, the pair of screw elements engaged with each other includes a male element in which a male screw is formed and a female element in which a female screw is formed. It is preferred that the element is displaced in the axial direction.
By adopting a configuration in which the male element is rotated, the rotation of the detection target can be transmitted to the male element only by matching the output axis of the detection target that rotates and the axis of the male element.

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

  According to the present invention, since the pair of screw elements and the sensor element are the main constituent elements, the rotation angle detection sensor can be provided at low cost.

It is a figure which shows the rotation angle detection sensor in this Embodiment. It is a figure which shows operation | movement of the rotation angle detection sensor 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 includes a stator 10 in which a female screw 18 is formed, a mover 20 in which a male screw 21 is formed, and an axial direction of the mover 20. And a detection unit 30 having a sensor element 31 in which a characteristic change occurs based on the displacement. The stator 10 and the movable element 20 forming a pair of screw elements constitute a screw mechanism by meshing with each other. This screw mechanism is constrained so that the stator 10 does not rotate.

[Stator 10]
The stator 10 includes a detection unit 11 and a guide unit 16. In the following description, the side on which the detection unit 11 is provided is defined as the upper side and the description proceeds.
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 the holding plate 15 is fixed to the upper end thereof. The holding plate 15 is provided with elasticity that can be flexed without difficulty when a later-described action end 23 is pressed.
The guide portion 16 is formed with a screw hole 17 penetrating in the axial direction. A female screw 18 is formed on the inner peripheral surface of the screw hole 17. The female screw 18 meshes with a male screw 21 provided on the mover 20.

[Mover 20]
The mover 20 is a member in which a male screw 21 that meshes with the female screw 18 of the stator 10 is formed in a predetermined range in the axial direction, a hemispherical working end 23 at one end, a lever 25 at the other end, Integrated.
When the movable element 20 receives an external force and is displaced in the axial direction, the action end 23 is pressed against the holding plate 15 to bend the holding plate 15 upward. The lever 25 is operated when the mover 20 is displaced. The mover 20 is displaced upward in the axial direction when the lever 25 is rotated clockwise (hereinafter may be referred to as forward rotation), and is displaced downward in the axial direction when the lever 25 is rotated counterclockwise.

The mover 20 is inserted into the screw hole 17 so that the male screw 21 of the mover 20 meshes with the female screw 18 of the stator 10. When the lever 20 is operated to rotate the mover 20, the movement of the stator 10 is restricted, so that the mover 20 is displaced in the axial direction while being guided by the stator 10.
As described above, the rotation angle detection sensor 1 according to this embodiment includes a displacement mechanism including the stator 10 and the mover 20.

[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 when the holding plate 15 is bent, distortion occurs according to the bending. 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 bending of the holding plate 15 based on the displacement of the mover 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 (movable element 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. 1, a state in which the working end 23 of the mover 20 is in contact with the back surface 15 b without applying a load to the holding plate 15 is set so that the rotation angle θ is 0 degree. However, this setting is an example, and the rotation angle θ in a state where a load is applied to the holding plate 15 can be set to 0 degree.
When the lever 25 is rotated forward, the mover 20 is displaced upward in the axial direction. Then, as shown in FIG. 2A, the action end 23 pushes up the holding plate 15, and the sensor element 31 is distorted. 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 movable element 20 is displaced upward in the axial direction 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 mover 20 is connected so that the axis of the mover 20 and the valve shaft 41 coincide. Therefore, when the valve shaft 41 is driven by the electric actuator 45, the mover 20 rotates following the valve shaft 41. When the mover 20 rotates, the voltage V detected from the sensor element 31 changes as the working end 23 moves up and down, so that the ECU 35 rotates the rotation angle θ of the lever 25 based on the voltage V, that is, the valve body 43. Can be detected. 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 rotation angle detection sensor 1 according to the present embodiment has been described with respect to the displacement mechanism in which the mover 20 is displaced in the axial direction when the mover 20 on which the male screw 21 is formed receives an external force and rotates. It is not limited to. For example, a member (hereinafter referred to as a female element) on which a female screw is formed can be displaced in the axial direction while rotating a member (hereinafter referred to as a male element) on which a male screw is formed. In this case, the male screw is restrained from displacement in the axial direction. Further, the male element can be displaced in the axial direction while rotating the female element, and the female element can be displaced in the axial direction while rotating the female element. That is, in the displacement mechanism of the present invention, by selecting an element that restrains displacement in the axial direction, when any one of the screw elements rotates, either one of the screw elements can be displaced.
However, among these displacement mechanisms, the displacement mechanism that rotates the male element described in the embodiment is preferable. Although the detection target in the present embodiment rotates, the rotation of the detection target can be transmitted to the male element only by connecting the output shaft that rotates along with the rotation and the axis of the male element so as to coincide with each other. On the other hand, when rotating the female element, if the outer diameter of the female element is considerably larger than the output shaft, another mechanical element (for example, for transmitting the rotation of the output shaft to the female element) (Gear) may be necessary.

  In the present embodiment, the strain gauge is described as an example of the sensor element 31, but other elements whose characteristics change based on the displacement of the screw element, for example, a piezoelectric element that outputs a voltage corresponding to the received pressure are used. It can also be used for sensor elements.

  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.

  Further, in the present embodiment, the sensor element 31 is provided on the holding plate 15 fixed to the support column 14, but as long as the characteristics of the sensor element change based on the displacement of the screw element, the site where the sensor element of the present invention is provided is It is not limited. For example, even if the sensor element 31 is fixed to the shell 12 of the stator 10 and the working end 23 of the movable element 20 is pressed against the shell 12, the characteristics of the sensor element 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.

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 Guide part 17 Screw hole 18 Female screw 20 Movable element 21 Male screw 23 Working end 25 Lever 30 Detection Part 31 sensor element 33 detector 35 ECU
40 Throttle valve 41 Valve shaft 43 Valve body 45 Electric actuator θ Rotation angle V Voltage

Claims (4)

A displacement mechanism that includes a pair of screw elements meshing with each other, and when any one of the screw elements is rotated by receiving an external force, the one screw element is displaced in the axial direction;
A sensor element in which a characteristic change occurs based on the displacement;
A rotation angle detection sensor comprising: The sensor element is a strain gauge;
The rotation angle detection sensor according to claim 1. A pair of screw elements that mesh with each other
It consists of a male element in which a male screw is formed and a female element in which a female screw is formed.
The male screw element is rotated in response to an external force, so that the male element is displaced in the axial direction.
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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