Multi-displacement detecting apparatus

• US 5,339,030 A
• Filed: 09/22/1992
• Issued: 08/16/1994
• Est. Priority Date: 09/25/1991
• Status: Expired due to Fees

• Current Assignee: Hunt Manufacturing Co. (Newell Brands Inc.), Okuma Corporation
• Original Assignee: Okuma Corporation
• Inventors: Hayashi, Yasukazu
• Primary Examiner(s): Wieder, Kenneth A.
• Assistant Examiner(s): Patidar, Jay M.
• Application Number:
  US07/948,309
• Time in Patent Office: 693 Days
• Field of Search: 324/207.17, 324/207.21, 324/207.23, 324/207.25, 324/207.26, 324/207.24, 318/661, 318/652, 318/653, 364/571.01, 364/167.01, 341/112, 341/116, 310/168, 310/83
• US Class Current: 324/207.23
• CPC Class Codes: G01B 7/312 for measuring eccentricity, i.e. lateral shift between two parallel axes
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: G01D 5/2046 by a movable ferromagnetic element, e.g. a core

Abstract

According to the present invention, multiple output signals of rotary displacement sensors are processed to detect a displacement different from a radial displacement in a moving direction. This results in a reduced number of displacement sensors. The present invention is a multi-displacement detecting apparatus, comprising: a moving section whose surface is continuously irregular in the moving direction; a stationary section including a plurality of sensors each outputting a signal that contains an output component whose level is proportional to a sine-wave value of a displacement in the moving direction and has an amplitude modulated in proportion to a variation in the gap from the irregular surface; and an arithmetic logic means for inputting the output signals of a plurality of sensors and outputting a displacement in the moving direction and other at least another displacement of the moving section.

Claims

1. A multi-displacement detecting apparatus, comprising:

a moving section whose surface is continuously irregular in the moving direction;

a stationary section including a plurality of sensors each outputting a signal that contains an output component whose level is proportional to a sine-wave value of a displacement in said moving direction and has an amplitude modulated in proportion to a variation in a gap from said irregular surface; and

an arithmetic logic means for inputting the output signals of said plurality of sensors and for outputting a displacement in said moving direction and another at least one displacement of said moving section;

wherein said arithmetic logic means converts the output signals of said plurality of sensors into a sine-wave value signal whose level is proportional to a sine-wave value of a displacement in said moving direction and a cosine-wave value signal whose level is proportional to a sine-wave value of a displacement in said moving direction and whose phase differs 90°

from said sine-wave value signal, and applies an inverse tangent to said sine-wave value signal and cosine-wave value signal, and provides a displacement in said moving direction, and wherein said arithmetic logic means also converts the output signals of said plurality of sensors into a first signal that varies according to a displacement in said moving direction and a second signal which is provided by modulating said first signal in amplitude proportionally to said variation in the gap, and dividing said second signal by said first signal, and providing a displacement in the gap direction.

2. A multi-displacement detecting apparatus according to claim 1, wherein said moving section is a cylindrical rotor made of a magnetic substance.

3. A multi-displacement detecting apparatus according to claim 2, wherein each of said plurality of sensors opposes the irregular surface of said moving section and has a plurality of teeth provided with a plurality of secondary coils and a primary coil that is excited by an AC signal.