Acceleration detecting device

• US 5,914,470 A
• Filed: 05/08/1997
• Issued: 06/22/1999
• Est. Priority Date: 06/29/1994
• Status: Expired due to Term

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Suzuki, Kyojiro, Nagura, Keiji, Kuwahara, Sadayuki
• Primary Examiner(s): Friedhofer, Michael A.
• Application Number:
  US08/853,490
• Time in Patent Office: 775 Days
• Field of Search: 73/1.37-1.39, 73/488, 73/514.01, 73/514.14, 73/514.36, 73/514.33, 73/514.38, 200/61.45 R-61.45 M, 280/735, 307/10.1
• US Class Current: 200/61.45R
• CPC Class Codes: G01P 15/135 by making use of contacts which are actuated by a movable inertial mass
• CPC Class Codes: H01H 35/14 Switches operated by change of acceleration, e.g. by shock or vibration, inertia switch wherein the liquid constitutes a contact of the switch H01H29/002

Abstract

When an acceleration more than a predetermined level is applied to a weight, a rotational moment is applied to a center of gravity of the weight, and therefore, the weight rotates around a shaft as a rotational center in a direction to be opposite to an elastic force given by plate springs. At this time, a rotor rotates in accordance with the rotation of the weight, the plate springs contacting respectively first cam and second cam move so as to narrow the clearance between the plate springs. When the rotor is rotated to a predetermined angle, contact points of the plate springs contact, and the contact state can be detected as an acceleration detecting signal through signal-output terminals. A stopper has two ends, and the two end are fixed to a cover to have a clearance portion between the cover and the stopper. When the weight and the stopper contact, the stopper is bent to the clearance portion side to absorb a shock due to the rotation of the weight.

Claims

1. An acceleration detecting device comprising:

a weight to rotate in correspondence with acceleration;

a shaft which is fixed to said weight and becomes a rotational center when said weight rotates;

a rotor which includes a cam portion and is supported in said shaft to rotate integrally with said weight;

a pair of plate springs of which a contact state changes in an actuating state when said rotor rotates by a predetermined angle;

a housing for fixing said shaft and said pair of plate springs;

a cover installed on said housing for covering said shaft and said pair of plate springs fixed to said housing; and

an shock-reducing member for regulating a further rotation of said weight after said contact state of said plate springs becomes in said actuating state and for elongating said actuating state, which is fixed to at least one of said housing and said cover and is disposed in a rotation passage of said weight to absorb a shock due to a rotational energy of said weight,

wherein said shock reducing member is an elastic member which absorbs the shock due to the rotational energy of said weight by deforming during contact with said weight, and

wherein said elastic member has opposite two ends, and

said two ends of said elastic member are fixed to said cover or said housing to have a space for bending said elastic member when said weight and said elastic member contact.

2. An acceleration detecting device according to claim 1, wherein

said elastic member has a cylindrical shape or a square-pole shape.

3. An acceleration detecting device according to claim 1, wherein

said elastic member has a plate shape that is formed integrally with said cover.

4. An acceleration detecting device according to claim 1, wherein

said weight has a hole formed thereon.

5. An acceleration detecting device according to claim 4, wherein

said hole penetrates through said weight.

6. An acceleration detecting device according to claim 4, wherein

said hole has a round shape.

7. An acceleration detecting device according to claim 1, wherein

said space for bending said elastic member is formed by reducing a thickness of said cover.

8. An acceleration detecting device comprising:

a weight to rotate in correspondence with acceleration;

a shaft which is fixed to said weight and becomes a rotational center when said weight rotates;

a rotor which includes a cam portion and is supported in said shaft to rotate integrally with said weight;

a pair of plate springs of which a contact state changes in an actuating state when said rotor rotates by a predetermined angle;

a housing for fixing said shaft and said pair of plate springs;

a cover installed on said housing for covering said shaft and said pair of plate springs fixed to said housing; and

an shock-reducing member for regulating a further rotation of said weight after said contact state of said plate springs becomes in said actuating state and for elongating said actuating state, which is fixed to at least one of said housing and said cover and is disposed in a rotation passage of said weight to absorb a shock due to a rotational energy of said weight,

wherein said elastic member is composed of a coil spring or a plate spring.

9. An acceleration detecting device comprising:

a weight to rotate in correspondence with acceleration;

a shaft which is fixed to said weight and becomes a rotational center when said weight rotates;

a rotor which includes a cam portion and is supported in said shaft to rotate integrally with said weight;

a pair of plate springs of which a contact state changes in an actuating state when said rotor rotates by a predetermined angle;

a housing for fixing said shaft and said pair of plate springs;

a cover installed on said housing for covering said shaft and said pair of plate springs fixed to said housing; and

an shock-reducing member for regulating a further rotation of said weight after said contact state of said plate springs becomes in said actuating state and for elongating said actuating state, which is fixed to at least one of said housing and said cover and is disposed in a rotation passage of said weight to absorb a shock due to a rotational energy of said weight,

wherein said pair of plate springs are disposed with a predetermined clearance interposed therebetween and respectively have tip portions,

at least one of said tip portion of said plate springs contacts said cam portion of said rotor for urging said rotor in a direction opposite to a direction of rotation of said rotor, and

said contact state becomes in said actuating state by rotation of said rotor when a predetermined acceleration is applied to said weight.

10. An acceleration detecting device according to claim 9, wherein

said cam portion of said rotor includes a first cam portion and a second cam portion,

said first and second plate springs respectively contact said first cam portion and said second cam portion, and

said first and second cam portions are disposed to contact said first plate spring and second plate spring when said predetermined acceleration is applied to weight.