Sensor for measuring acceleration and tilt with a bubble level

• US 5,351,539 A
• Filed: 05/26/1992
• Issued: 10/04/1994
• Est. Priority Date: 11/29/1989
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Foell, Uwe, Kippelt, Ulrich, Ziegenbein, Botho
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US07/839,757
• Time in Patent Office: 861 Days
• Field of Search: 73/500, 73/516 LM, 33/366, 338/22 SD, 338/27, 338/44
• US Class Current: 73/500
• CPC Class Codes: G01C 9/06 Electric or photoelectric indication or reading means
• CPC Class Codes: G01C 9/36 of the spherical type, i.e. for indicating the level in all directions
• CPC Class Codes: G01P 15/008 by using thermal pick-up
• CPC Class Codes: G01P 15/12 by alteration of electrical resistance G01P15/0897, G01P15/105 take precedence

Abstract

A sensor is proposed which is used for detecting the acceleration and the inclination of a movable object (10), in particular a motor vehicle. A bubble level (11) is fixed on the object (10). The bubble level (11) comprises a housing (12), a liquid (16) contained in the housing (12) and a gas bubble (17) contained in the housing (12). The liquid (16) and the gas bubble (17) together completely fill the hollow chamber (15) enclosed by the housing (12), so that the gas bubble (17) is not completely enclosed by the liquid (16), but lies against the interior of the housing (12), so that the surface separating the liquid and the gas pushes against the interior of the housing (12). The gas bubble (17) is in an initial position inside the housing (12) when the acceleration and the inclination of the bubble level (11) are equal to zero or their effects are mutually canceled out. On the inside of the housing (12), within that area over which the gas bubble (17) extends in the said initial position, an electrically heatable, temperature-sensitive electrical circuit element (RS) is disposed, which is a component of an evaluation circuit, which generates an output signal (U_D) which is a function of the acceleration and the inclination of the bubble level (11).

Claims

1. A sensor for detecting the acceleration and the inclination of a movable object (10), with the aid of a bubble level (11) secured to the movable object (10),

comprising

a housing (12),

a liquid (16) partially filling the housing (12), while leaving a gas bubble (17) in a portion of the housing,

where the liquid (16) and the gas bubble (17) together completely fill a hollow chamber (15) defined by the housing (12), so that the gas bubble is not completely enclosed by the liquid (16), but lies against the interior of the housing (12), so that an interface separating the liquid and the gas contacts the interior of the housing (12) and

where the gas bubble (17) is in an initial position inside the housing (12) when the acceleration and the inclination of the bubble level (11) are equal to zero or their effects cancel each other,

where furthermore the sensor has an electrically heatable, temperature-sensitive electrical circuit element (RS) and the electrical circuit element (RS) is a component of an evaluation circuit, which generates an output signal (U_D) which is a function of the acceleration and the inclination of the bubble level (11), and wherein,

on the inside of the housing (12), within that area over which the gas bubble (17) extends in said initial position, the housing (12) consists of a lower housing body (13) and a cover plate (14),

the electrical circuit element (RS) is disposed on a surface side of the cover plate (14) oriented towards the lower housing body (13), and

the circuit element (RS) is formed on the cover plate (14) by thick-film production techniques.

2. A sensor in accordance with claim 1, further comprising means for heating the electrical circuit element is heatable by causing an electric current to flow through the electrical circuit element (RS).

3. A sensor in accordance with claim 1,

wherein the electrical circuit element (RS) is an ohmic resistance element.

4. A sensor in accordance with claim 3,

wherein the ohmic resistance element (RS) is a film resistance element.

5. A sensor in accordance with claim 4,

wherein the ohmic resistance element (RS) is housed in a bubble (21) consisting of a glass-ceramic material, which is arched on the inside of the housing (12), on the surface side of the cover plate (14) oriented towards the lower housing body (13).

6. A sensor in accordance with claim 5,

wherein the bubble (21) contains a diaphragm (23) produced in thick-film technique, on which the film resistance element (RS) is disposed.

7. A sensor in accordance with claim 1,

characterized in that

further electric circuit elements (RT₁, RT₂, D₁, D₂, D₃) are applied to the cover plate (14) formed as a hybrid plate, which are components of the evaluation circuit.

8. A sensor in accordance with claim 7,

wherein said further electric circuit elements (RT₁, RT₂, D₁, D₂, D₃) are disposed on the surface side of the cover plate (14) oriented towards the lower housing body (13).

9. A sensor in accordance with claim 1,

wherein

the hollow chamber (15) enclosed by the housing (12) has the shape of a truncated cone, at least in the vicinity of the initial position of the gas bubble (17).

10. A sensor in accordance with claim 9,

wherein the gradient of slope of the truncated cone is 21°

.

11. A sensor in accordance with claim 2,

characterized in that

further electric circuit elements (RT₁, RT₂, D₁, D₂, D₃) are applied to the cover plate (14) formed as a hybrid plate, which are components of the evaluation circuit.

12. A sensor in accordance with claim 3,

characterized in that

further electric circuit elements (RT₁, RT₂, D₁, D₂, D₃) are applied to the cover plate (14) formed as a hybrid plate, which are components of the evaluation circuit.

13. A sensor in accordance with claim 4,

characterized in that

further electric circuit elements (RT₁, RT₂, D₁, D₂, D₃) are applied to the cover plate (14) formed as a hybrid plate, which are components of the evaluation circuit.

14. A sensor in accordance with claim 5,

characterized in that

further electric circuit elements (RT₁, RT₂, D₁, D₂, D₃) are applied to the cover plate (14) formed as a hybrid plate, which are components of the evaluation circuit.

15. A sensor in accordance with claim 6,

characterized in that

further electric circuit elements (RT₁, RT₂, D₁, D₂, D₃) are applied to the cover plate (14) formed as a hybrid plate, which are components of the evaluation circuit.