Acceleration sensor and acceleration sensing system

• US 5,233,872 A
• Filed: 08/16/1990
• Issued: 08/10/1993
• Est. Priority Date: 08/28/1989
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd., Zexel Corporation
• Original Assignee: Nissan Motor Co., Ltd., Zexel Corporation
• Inventors: Kushida, Takeo, Kurozu, Tomotaka, Ohmura, Issei, Takeuchi, Mikio
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US07/568,050
• Time in Patent Office: 1,090 Days
• Field of Search: 73/497, 73/516 R, 73/517 R, 73/517 B, 73/654
• US Class Current: 73/497
• CPC Class Codes: G01P 1/006 used for thermal compensation
• CPC Class Codes: G01P 15/11 by inductive pick-up

Abstract

An acceleration sensor includes a tubular bobbin only one end of which is fixed to a body whereas the other end is movable relative to the body axially of the bobbin. Supported on the body are magnets for attracting a magnetic member, mounted within the bobbin, to a reference position. A detection member is mounted around the bobbin so as to detect a displacement of the magnetic member from the reference position. A gel can be filled in a receiving space of the body in which the bobbin is received. The body can be of a tubular shape, with covers fixedly secured respectively to opposite ends of the body, in which case opposite ends of the bobbin are disposed in opposed, spaced relation to inner sides of the covers, respectively. The body can be received in a housing, and a circuit board can be received in an auxiliary receiving space in the housing. An acceleration sensing system incorporating such a sensor includes a processing circuit for processing an output of the detection member to output a detection signal representative of the direction and magnitude of the acceleration. The processing circuit has a temperature compensation circuit for compensating for a temperature variation so as to keep the detection signal at a constant level when the acceleration is zero.

Claims

1. An acceleration sensor comprising:

(a) a housing having an internal space;

(b) a body having a receiving space, said body being received in said internal space, and that portion of said internal space other than the portion of said housing occupied by said body serving as an auxiliary receiving space;

(c) a tubular bobbin received in said receiving space of said body, said tubular bobbin being fixed at only one of its opposite ends to said body, and the other end of said bobbin being movable relative to said body in a direction of the axis of said bobbin;

(d) a magnetic member received within said bobbin for movement in the direction of the axis of said bobbin;

(e) magnet means for attracting said magnetic member to a reference position within said bobbin, said magnet means being disposed radially outwardly of said bobbin and supported on said body;

(f) detection means mounted on an outer periphery of said bobbin so as to detect a displacement of said magnetic member from said reference position; and

(g) a circuit board electrically connected to said detection means, said circuit board being received in said auxiliary receiving space of said housing;

wherein said body has a tubular shape, a partition plate being secured to one end of said body, and said partition plate separating said receiving space of said body from said auxiliary receiving space of said housing;

wherein the bobbin is positioned in such a manner that one end of said bobbin is disposed close to said auxiliary receiving space of the housing whereas the other end of said bobbin is disposed remote from said auxiliary receiving space; and

wherein a rigid resin is filled in said auxiliary receiving space of said housing, and a gel material is filled in said receiving space of said body.

2. An acceleration sensor comprising:

(a) a housing having an internal space;

(b) a body having a receiving space, said body being received in said internal space, and that portion of said internal space other than that portion of said housing occupied by said body serving as an auxiliary receiving space;

(c) a tubular bobbin received in said receiving space of said body, said tubular bobbin being fixed at only one of its opposite ends to said body, and the other end of said bobbin being movable relative to said body in a direction of the axis of said bobbin;

(d) a magnetic member received within said bobbin for movement in the direction of the axis of said bobbin;

(e) magnet means for attracting said magnetic member to a reference position within said bobbin, said magnet means being disposed radially outwardly of said bobbin and supported on said body;

(f) detection means mounted on an outer periphery of said bobbin so as to detect a displacement of said magnetic member from said reference position; and

(g) a circuit board electrically connected to said detection means, said circuit board being received in said auxiliary receiving space of said housing;

wherein said body has a tubular shape, a partition plate being secured to the one end of said body, and said partition plate separating said receiving space of said body from said auxiliary receiving space of said housing;

wherein the bobbin is positioned in such a manner that one end of said bobbin is disposed close to said auxiliary receiving space of the housing whereas the other end of said bobbin is disposed remote from said auxiliary receiving space;

wherein said bobbin has an end wall formed at the one end thereof, a plurality of terminals being formed on said end wall and extending through said partition wall toward said auxiliary receiving space of said housing, and said detection means being electrically connected to said circuit board via said terminals; and

wherein a rigid resin is filled in said auxiliary receiving space of said housing, and a gel material is filled in said receiving space of said body.

3. An acceleration sensor comprising:

(a) a housing having an internal space;

(b) a body having a receiving space, said body being received in said internal space, and that portion of said internal space other than that portion of said housing occupied by said body serving as an auxiliary receiving space;

(c) a tubular bobbin received in said receiving space of said body, said tubular bobbin being fixed at only one of its opposite ends to said body, and the other end of said bobbin being movable relative to said body in a direction of the axis of said bobbin;

(d) a magnetic member received within said bobbin for movement in the direction of the axis of said bobbin;

(e) magnet means for attracting said magnetic member to a reference position within said bobbin, said magnet means being disposed radially outwardly of said bobbin and supported on said body;

(f) detection means mounted on an outer periphery of said bobbin so as to detect a displacement of said magnetic member from said reference position; and

(g) a circuit board electrically connected to said detection means, said circuit board being received in said auxiliary receiving space of said housing;

wherein said circuit board has a processing circuit for processing an output of said detection means to produce a detection signal representative of the direction and magnitude of the acceleration, said processing circuit having a temperature compensation circuit for compensating for a variation of the output of said detection means due to a variation of the relative position between said magnet means and said detection means in the direction of the axis of said bobbin, so as to keep said detection signal at a constant level when the acceleration is zero, and said variation of the relative position being caused by a temperature variation; and

wherein a rigid resin is filled in said auxiliary receiving space of said housing, and a gel material is filled in said receiving space of said body.

4. An acceleration sensor according to claim 3, in which said detection means comprises a differential transformer having a primary coil and a pair of secondary coils, said processing circuit comprising a primary exciting signal-generating circuit for outputting a primary exiting signal of high frequency to said primary coil of said differential transformer, a synchronous rectifying-smoothing circuit for effecting synchronous rectification and smoothing of a differential output of said second coils, and an output circuit for amplifying a voltage difference between a reference voltage and an output of said synchronous rectifying-smoothing circuit and for adding said reference voltage to the amplified voltage difference, and said output circuit having an element for varying said reference voltage in accordance with a temperature variation, so that said output circuit functions as said temperature compensation circuit.

5. An acceleration sensing system comprising:

(a) a body;

(b) a tubular bobbin which is fixed at only one of its opposites ends to said body, the other end of said bobbin being movable relative to said body in a direction of the axis of said bobbin;

(c) a magnetic member received within said bobbin for movement in the direction of the axis of said bobbin;

(d) magnet means for attracting said magnetic member to a reference position within said bobbin, said magnet means being disposed radially outwardly of said bobbin and supported on said body;

(e) detection means received on an outer periphery of said bobbin so as to detect a displacement of said magnetic member from said reference position; and

(f) a processing circuit for processing an output of said detection means to produce a detection signal representative of the direction and magnitude of the acceleration, said processing circuit having a temperature compensation circuit for compensating for a variation of the output of said detection means due to a variation of the relative position between said magnet means and said detection means in the direction of the axis of said bobbin, so as to keep said detection signal at a constant level when the acceleration is zero, and said variation of the relative position being caused by a temperature variation.