| 摘要 |
<p>Speed Sensing Apparatus A sensing apparatus (10) determines motion of a movable element (24) by detecting fluctuations in magnetic flux density. These fluctuations are caused by, for example, the teeth on a gear (34), where rotation of the gear (34) sequentially presents each of the teeth and a corresponding recess in close proximity with the sensor (18). The flux density is consequently altered at a frequency directly related to the rotational speed of the gear (34). Optimizing the system requires a high signal to noise ratio, thus the air gap between the gear (34) and apparatus (10) must be established at a minimum valve. Eccentricity of the gear (34), as well as actual radial movement of the gear (34), are accommodated by the use of a plunger element (14) which is axially movable within a first body (12) in response to contact with the gear (34). A coiled spring (26) annularly disposed about the plunger (14) in an endless configuration engage the plunger (14) and an inner surface (22) of the body (12) to provide a frictional force of a magnitude sufficient to maintain the plunger (14) at a selected position and allow movement in response to actual contact between the apparatus (10) and the gear (34) which prevents damage to the plunger (14) and establishes a minimum axial air gap. Alternately, a segmented spring (30) is connected to the plunger (14) and contacts the inner surface (22) of the body (12).</p> |
