Pressure sensor device

A pressure sensor device prevents foreign matters from reaching a pressure sensor at the back of a pressure introducing passage, is superior in resistance against both fouling and freezing, and includes a temperature sensor. The pressure sensor device comprises a pressure sensor including a pressure detecting element is disposed to define an enclosed reference chamber and an enclosed pressure introducing chamber and is deformed depending on a pressure difference between the reference chamber and the pressure introducing chamber for detecting the pressure of an object to be measured, a pipe connected to the pressure introducing chamber, and a lead-out portion; a temperature sensor including a heat sensitive element for detecting the temperature of the measured object and a lead-out portion; and a sensor container containing the pressure sensor and the temperature sensor therein and including a pressure introducing passage formed therein which has one end air-tightly connected to the pipe and the other end being open to the exterior, and also has a labyrinth structure, the sensor container including a temperature sensor containing projection formed to accommodate the heat sensitive element embedded in its distal end portion.

What is claimed is:

1. A sensor device comprising:

a pressure sensor having a pressure detecting element, a pipe, and a lead-out portion, said pressure detecting element having an enclosed reference chamber and an enclosed pressure introducing chamber, wherein said pressure detecting element is deformed depending on a pressure difference between a pressure inside said reference chamber and a pressure inside said pressure introducing chamber for detecting the pressure of an external object to be measured, and wherein said pipe is connected to said pressure introducing chamber for introducing said external object to be measured to said pressure introducing chamber, and wherein said lead-out portion outputs a value detected by said pressure detecting element;

a temperature sensor disposed adjacent to said pressure sensor, said temperature sensor having a heat sensitive element for detecting the temperature of the measured object and a second lead-out portion extending from said beat sensitive element for outputting a value detected by said heat sensitive element; and

a sensor container for containing said pressure sensor and said temperature sensor therein, said sensor container having a pressure introducing passage and a temperature sensor containing projection formed therein, wherein said pressure introducing passage has one end air-tightly connected to said pipe and an other end open to the exterior so that the pressure of said external object to be measured can be transmitted to said pressure sensor, and wherein said pressure introducing passage has a labyrinth structure capable of preventing intrusion of foreign material into said pressure sensor, and wherein said temperature sensor containing projection is formed to project from the vicinity of the opening at said other end of said pressure introducing passage, and wherein said heat sensitive element is embedded in a distal end portion of said temperature sensor containing projection.

2. A sensor device comprising:

a pressure sensor having an enclosed reference chamber, a pressure detecting element which comprises an enclosed pressure introducing chamber inside said reference chamber and which is deformed depending on a pressure difference between said reference chamber and said pressure introducing chamber for detecting the pressure of an external object to be measured, a pipe connected to said pressure introducing chamber for introducing said external object to be measured to said pressure introducing chamber, and a lead-out portion for outputting a value detected by said pressure detecting element; and

a sensor container containing said pressure sensor therein, said sensor container having a pressure introducing passage formed therein, said pressure introducing passage having one end air-tightly connected to said pipe and an other end open to the exterior so that the pressure of said external object to be measured can be transmitted to said pressure sensor, said pressure introducing passage also having a labyrinth structure capable of preventing intrusion of foreign material into said pressure sensor,

wherein said labyrinth structure comprises a cylindrical sub-chamber having one end air-tightly connected to said pipe and an other end given by a bottom portion, and a small passage formed by boring a part of said bottom portion corresponding to a maximum inner diameter of said sub-chamber such that said sub-chamber is open to the exterior through said small passage, and wherein an opening of said small passage made open to the exterior is positioned radially outward of an inner wall of said sub-chamber.

3. A sensor device as claimed in claim 1, wherein said labyrinth structure comprises a cylindrical sub-chamber having one end air-tightly connected to said pipe and an other end given by a bottom portion, and a small passage formed by boring a part of said bottom portion corresponding to a maximum inner diameter of said sub-chamber such that said sub-chamber is open to the exterior through said small passage, and wherein an opening of said small passage made open to the exterior is positioned radially outward of an inner wall of said sub-chamber.

4. A sensor device as claimed in claim 3, wherein said small passage is formed in plural number such that said plural number of small passages are positioned at intervals in a circumferential direction around said maximum inner diameter of said sub-chamber.

5. A sensor device as claimed in claim 3, wherein said bottom portion has a generally conical shape with a raised central area.

6. A sensor device as claimed in claim 3, wherein said sub-chamber has a volume not less than 0.2 cm.sup.3 and said small passage has a sectional area not more than 0.1 cm.sup.2.

7. A sensor device as claimed in claim 3, further comprising a protective plate disposed between said sub-chamber and said pipe, said protective plate having through holes bored in a primary surface of said protective plate and shield portions formed to cover said through holes while leaving a predetermined distance between said shield portions and said primary surface, whereby said external object to be measured passes said through holes after going around said shield portions.

8. A sensor device as claimed in claim 7, wherein said protective plate is made of a material having a specific heat less than a specific heat of a material included in said sensor container.

9. A sensor device as claimed in claim 7, wherein a piece of unwoven cloth is disposed between said primary surface of said protective plate and said shield portions so as to cover said through holes, and wherein said piece of unwoven cloth is impregnated with at least one of oil and grease.

10. A sensor device as claimed in claim 7, wherein a metal mesh filter is disposed between said primary surface of said protective plate and said shield portions so as to cover said through holes.

11. A sensor device as claimed in claim 1, wherein said sensor container is attached to an attachment hole bored in a wall of a system such that an attachment surface formed along an outer peripheral portion of said sensor container is air-tightly engaged with an inner surface of said attachment hole, and wherein said temperature sensor containing projection is projected so that a portion thereof extends into an interior space of said system, and wherein said temperature sensor containing projection has a bottom-equipped tubular portion containing said heat sensitive element in a distal end portion, and wherein a resin having high thermal conductivity is disposed around said heat sensitive element so that an air layer is formed between said resin and said attachment surface.

12. A sensor device as claimed in claim 1, wherein a circuit board is disposed in said sensor container and wherein said temperature sensor is electrically connected to said circuit board through a flexible board.

13. A sensor device as claimed in claim 2, further comprising a protective plate disposed between said sub-chamber and said pipe, said protective plate having through holes bored in a primary surface of said protective plate and shield portions formed to cover said through holes while leaving a predetermined distance between said shield portions and said primary surface, whereby said external object to be measured passes said through holes after going around said shield portions.

14. A sensor device as claimed in claim 2, wherein said small passage is formed in plural number such that said plural number of small passages are positioned at intervals in a circumferential direction around said maximum inner diameter of said sub-chamber.

15. A sensor device as claimed in claim 2, wherein said bottom portion has a generally conical shape with a raised central area.

16. A sensor device as claimed in claim 2, wherein said sub-chamber has a volume not less than 0.2 cm.sup.3 and said small passage has a sectional area not more than 0.1 cm.sup.2.

17. A sensor device as claimed in claim 13, wherein a metal mesh filter is disposed between said primary surface of said protective plate and said shield portions so as to cover said through holes.

18. A sensor device as claimed in claim 13, wherein said protective plate is made of a material having a specific heat less than a specific heat of a material included in said sensor container.

19. A sensor device as claimed in claim 13, wherein a piece of unwoven cloth is disposed between said primary surface of said protective plate and said shield portions so as to cover said through holes, and wherein said piece of unwoven cloth is impregnated with at least one of oil and grease.