| 摘要 |
PURPOSE:To make it possible to detect the opening degree of a throttle valve without adding an additional component to the torque to open and close the valve by a method wherein the variation of the opening degree of the throttle valve is detected as the variation of an output voltage due to the variation of the amount of light received by a light receiver. CONSTITUTION:A semicircular shielding member 17 is formed on one end of a shaft 10a of the throttle valve 10 in such a manner that the member 17 projects from the shaft 10a in the direction normal to the latter and a projector 14 and a light receiver 16 are arranged in a throttling degree detector 12 so as to sandwich the shielding member 17. In this case, the center O of the shielding member 17 is made to lie on the center line of a projected beam of light B and the diameter 2r of the member 17 is made equal to the width of the projected beam of light B. Thus, when the throttle valve 10 is opened to the full, the surface 17a of the shielding member 17 comes to lie parallel to the center line of the projected beam of light B as shown in the drawing so that the amount of light B reaching the light receiver 16 becomes maximum. As a result, the amount of light received by the light receiver 16 decreases as the valve 10 opens and a voltage signal proportional to the opening degree of the valve 10 is obtained through an amplifying circuit 15. |
