Differential pressure sensor having symmetrically-provided sensor chips and pressure introduction passages

• US 20080000302A1
• Filed: 06/28/2007
• Published: 01/03/2008
• Est. Priority Date: 06/29/2006
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Ueno, Masato
• Granted Patent: US 7,516,667 B2
• Time in Patent Office: Days
• US Class Current: 73/717
• CPC Class Codes: G01L 15/00 Devices or apparatus for measuring two or more fluid pressure values simultaneously
• CPC Class Codes: G01L 19/0038 being part of the housing other details about the housing G01L19/14
• CPC Class Codes: G01L 19/141 Monolithic housings, e.g. molded or one-piece housings
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation

Abstract

A differential pressure sensor includes a case, a first and a second pressure sensing element, a first and a second pressure introduction passage, and a differential pressure determining element. The first and second pressure sensing elements work to respectively sense a first and a second pressure. The first and second pressure introduction passages are provided to respectively introduce the first and second pressures to the first and second pressure sensing elements. The differential pressure determining element works to determine a differential pressure as the difference between the first and second pressures sensed by the first and second sensing elements. The first and second pressure sensing elements have the same shape and size and are symmetrically arranged in the case with respect to a reference. The first and second pressure introduction passages also have the same shape and size and are symmetrically positioned in the case with respect to the reference.

Claims

1. A differential pressure sensor comprising:

a case;

a first and a second pressure sensing element received in the case, the first pressure sensing element working to sense a first pressure and output a first electrical signal representative of the sensed first pressure, the second pressure sensing element working to sense a second pressure and output a second electrical signal representative of the sensed second pressure;

a first and a second pressure introduction passage which are provided in the case to introduce the first and second pressures to the first and second pressure sensing elements, respectively; and

a differential pressure determining element working to determine a differential pressure, which is the difference between the first and second pressures, based on the first and second electric signals output from the first and second pressure sensing elements, the differential pressure determining element also working to output an electrical signal representative of the determined differential pressure,

wherein the first and second pressure sensing elements have the same shape and size and are symmetrically arranged in the case with respect to a reference, and

the first and second pressure introduction passages also have the same shape and size and are symmetrically positioned in the case with respect to the reference.

2. The differential pressure sensor as set forth in claim 1, wherein a separation wall is provided in the case to separate the first and second pressure introduction passages, and

the reference, with respect to which the first and second pressure sensing elements are symmetrically arranged and the first and second pressure introduction passages are symmetrically positioned, is made up of the separation wall.

3. The differential pressure sensor as set forth in claim 2, wherein at least part of the separation wall is made of a material having higher heat conductivity than that of the case.

4. The differential pressure sensor as set forth in claim 1, wherein the reference is made up of a hypothetical center line of the case so that when viewed along the center line, the first and second pressure sensing elements and the first and second pressure introduction passages are respectively in point symmetry with respect to the center line.

5. The differential pressure sensor as set forth in claim 1, wherein each of the first and second pressure introduction passages has a circular cross-section portion,

the circular cross-section portions of the first and second pressure introduction passages have the same shape and size and are symmetrically positioned with respect to the reference, and

the first and second pressure sensing elements are coaxially arranged with the circular cross-section portions of the first and second pressure introduction passages, respectively.

6. The differential pressure sensor as set forth in claim 1, wherein the differential pressure determining element is symmetrically arranged in the case with respect to the reference.

7. The differential pressure sensor as set forth in claim 1, wherein the case is made of a resin and an additive, and

the additive is substantially symmetrically distributed in the case with respect to the reference.

8. The differential pressure sensor as set forth in claim 1, further comprising a first and a second pressure transmission medium that are filled in the first and second pressure introduction passages to transmit the first and second pressures to the first and second pressure sensing elements, respectively,

wherein the first and second pressure transmission mediums are formed to have the same shape and size and be symmetric with respect to the reference.

9. The differential pressure sensor as set forth in claim 8, wherein the first and second pressure transmission mediums are made of the same gel-like material.

10. The differential pressure sensor as set forth in claim 1, further comprising a third and a fourth pressure introduction passages which are provided in the case to introduce a reference pressure respectively to the first and second pressure sensing elements,

wherein the case has a first and a second end face that are opposite to each other,

the first and second pressure introduction passages are formed through the first end face of the case, and the third and fourth pressure introduction passages are formed through the second end face of the case,

the first pressure sensing element is configured to sense the first pressure as a first relative pressure to the reference pressure, and the second pressure sensing element is configured to sense the second pressure as a second relative pressure to the reference pressure, and

the differential pressure determining element is configured to determine the differential pressure as the difference between the first and second relative pressures.

11. The differential pressure sensor as set forth in claim 10, further comprising a third and a fourth pressure transmission medium which are filled in the third and fourth pressure introduction passages to transmit the reference pressure to the first and second pressure sensing elements and absorb heat from the first and second pressure introduction passages, respectively,

wherein the third pressure transmission medium is formed with a larger amount of a gel-like material than the fourth pressure transmission medium.

12. The differential pressure sensor as set forth in claim 10, further comprising a pressure transmission medium which is filled only in the third one of the third and fourth pressure introduction passages to transmit the reference pressure to the first pressure sensing element and absorb heat from the first pressure introduction passage.