Acceleration detector

• US 4,825,696 A
• Filed: 10/28/1987
• Issued: 05/02/1989
• Est. Priority Date: 03/20/1986
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Seipler, Dieter
• Primary Examiner(s): Levy, Stewart J.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/130,228
• Time in Patent Office: 552 Days
• Field of Search: 73/517 R, 73/517 B, 73/493, 73/518, 73/862.65, 338/2, 338/5, 338/46, 280/735
• US Class Current: 73/514.33
• CPC Class Codes: G01P 15/12 by alteration of electrical resistance G01P15/0897, G01P15/105 take precedence

Abstract

An acceleration detector, the spring is a substrate plate, e.g., of Al₂ O₃, which is fixed at one end in a housing. The resistors and the evaluating circuit are arranged on the spiral spring and can be applied to the substrate plate in a single work step using thick-film technology.

Claims

1. An acceleration detector for triggering passenger protection devices in motor vehicles, comprising a plate-like spring;

means for fixing one end portion of said spring while leaving the opposite end portion free;

means for retaining an intermediate portion of said spring to define a non-bending spring area between the intermediate and the fixed end portions, and a flexible spring area between the free end and the intermediate portions;

a seismic mass secured to said free end portion to form therewith a flexural resonator;

at least one expansion sensitive resistor arranged on said flexible spring area; and

an active evaluation circuit arranged on said non-bending spring area and being connected to said at least one expansion sensitive resistor to evaluate its condition.

2. An accelerator detector as defined in claim 1 wherein said spring is a flexible substrate plate of a ceramic material.

3. An accelerator detector as defined in claim 2 wherein said flexible substrate plate is formed of aluminum oxide.

4. An accelerator detector as defined in claim 2 wherein said at least one expansion sensitive resistor and said evaluation circuit are applied on said flexible substrate plate by a thick-film technology.

5. An accelerator detector as defined in claim 1 wherein said one end portion of said spring is fixed in a plastic housing.

6. An accelerator detector as defined in claim 1 wherein said retaining means almost contact intermediate upper and lower regions of said plate-like spring.