JP2009264945A - Pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure sensor which is usable, even in a high-temperature region. <P>SOLUTION: This pressure sensor 10 includes a housing 20 fixed to a pipe for measurement; a connector case 30 with a specific heat smaller than that of the housing 20; a sensor element 44 for outputting an electrical signal, according to the deformation of a diaphragm 42 by the pressure of a medium to be detected, and an annular substrate 50 for generating an output signal, according to the electric signal. The sensor element 44 and annular substrate 50 are arranged in and cooling liquid W is filled into a cooling chamber Sc formed, by assembling the housing 20 to the connector case 30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pressure sensor used in a high temperature region.

  Conventionally, the pressure sensor shown in the following patent document 1 is known as a pressure sensor used in a high temperature region. This pressure sensor includes a metal stem having a diaphragm that can be deformed according to the detected pressure, and the detected pressure based on the resistance value of the strain gauge that changes according to the diaphragm that is deformed by the detected pressure. Is detected.

In this pressure sensor, the PN junction portion is eliminated by configuring the strain gauge with only a single conductivity type impurity (for example, P-type impurity). For this reason, current leakage at the PN junction portion is eliminated, and use in a high temperature region is possible.
JP 2007-271280 A

  However, if it is possible to use in a high temperature region by adopting a special strain gauge as described above, it is necessary to provide other elements with higher heat resistance, which increases the manufacturing cost of the pressure sensor. is there.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a pressure sensor that can be used even in a high temperature region.

  In order to achieve the above object, in the pressure sensor according to claim 1, a housing (20) capable of being attached to a mounted member through which a detected medium flows, wherein the detected medium is introduced. A housing in which an introduction hole (24) is formed, a connector case (30) having a terminal (31) for exchanging signals with the outside, and a connector case having a smaller specific heat than the housing; A diaphragm (42) that is displaced according to a detected pressure of the detected medium introduced through the introduction hole, a sensor element (44) that detects the detected pressure based on a displacement of the diaphragm, and A sealed space (Sc) formed by assembling a housing and the connector case, wherein the sensor element is disposed therein; And Technical characterized in that it comprises an insulating liquid (W) is filled in the sealed space.

  According to the first aspect of the present invention, a sealed member is formed by assembling a mounted member through which a medium to be detected flows, for example, a housing that can be mounted on an engine measurement pipe, and a connector case having a specific heat smaller than that of the housing. The sensor element is disposed in the space and filled with an insulating liquid.

  When the detected medium and the mounted member through which the detected medium flows are at a high temperature, the housing attached to the mounted member is at a high temperature. On the other hand, since the specific heat of the connector case is smaller than that of the housing, the heat of the housing is difficult to be transmitted, so the temperature is lower than that of the housing.

  For this reason, the temperature of the insulating liquid near the housing in the sealed space is higher than that of the insulating liquid near the connector case in the sealed space. When a temperature difference occurs in the insulating liquid in this way, the insulating liquid convects in the sealed space, and the housing is cooled by heat exchange between the housing that is the high temperature portion and the insulating liquid, and the connector that is the low temperature portion. The insulating liquid itself is cooled by heat exchange between the case and the insulating liquid.

Further, heat is transmitted to the sensor element from a housing or the like which is a high temperature part. At this time, since the sensor element is disposed in the sealed space where the insulating liquid convects, heat exchange is performed between the sensor element and the insulating liquid, and the sensor element can be cooled. In particular, since the sensor element is cooled, it is not necessary to increase the heat resistance of other peripheral elements as compared to the case of using a sensor element with increased heat resistance for use in a high temperature region, and the heat resistance An increase in manufacturing cost can be suppressed.
Therefore, the pressure sensor configured as described above can be used even in a high temperature region.

  In the invention of claim 2, a circuit element for processing a signal output from the sensor element and outputting it to the outside via a terminal of the connector case is provided, and this circuit element is disposed in the sealed space. . Thereby, a circuit element can be cooled similarly to a sensor element.

  In the invention of claim 3, one or a plurality of concave grooves are formed on the outer periphery of the housing. Thereby, since the surface area of the outer periphery of a housing becomes large, the heat dissipation effect of a housing can be improved. As a result, since the temperature rise of the insulating liquid is suppressed, the cooling effect of the sensor element or the like can be improved.

  According to the fourth aspect of the present invention, one or a plurality of convex protrusions are formed on the outer periphery of the housing. Even in this case, since the surface area of the outer periphery of the housing is increased, the heat dissipation effect of the housing can be enhanced. As a result, since the temperature rise of the insulating liquid is suppressed, the cooling effect of the sensor element or the like can be improved.

  In the invention of claim 5, one or a plurality of concave grooves are formed on the inner periphery of the housing constituting the sealed space. Thereby, since the surface area of the inner periphery of the housing is increased, heat exchange between the housing and the insulating liquid can be promoted. As a result, the cooling effect of the housing is improved, so that an increase in temperature of the sensor element due to heat transfer from the housing can be suppressed.

  According to the sixth aspect of the present invention, one or a plurality of convex projections are formed on the inner periphery of the housing constituting the sealed space. Even in this case, since the surface area of the inner periphery of the housing is increased, heat exchange between the housing and the insulating liquid can be promoted. As a result, the cooling effect of the housing is improved, so that an increase in temperature of the sensor element due to heat transfer from the housing can be suppressed.

  In the invention of claim 7, the connector case is formed with an internal pressure adjusting space partitioned by an elastic film with respect to the sealed space. The insulating liquid filled in the sealed space thermally expands as the temperature rises. At this time, the connector case is formed with an internal pressure adjusting space partitioned by the elastic film with respect to the sealed space, so that the elastic film elastically enters the internal pressure adjusting space according to the thermal expansion of the insulating liquid. The sealed space is widened by the deformation. Thereby, since the pressure of the insulating liquid in the sealed space is kept constant, it is possible to suppress the pressure caused by the thermal expansion of the insulating liquid from affecting the displacement of the diaphragm.

  In the invention of claim 8, the connector case is formed with a communication hole for communicating the internal pressure adjusting space with the atmosphere. Thereby, the pressure of the internal pressure adjusting space is adjusted so as to be always equal to the atmospheric pressure without changing according to the ambient temperature, so that the influence of the thermal expansion of the insulating liquid in the sealed space can be reliably suppressed. .

  Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view illustrating a schematic configuration of a pressure sensor 10 according to the present embodiment.

The pressure sensor 10 is a sensor that detects, for example, the pressure of a medium to be detected (detected pressure) flowing in a measurement pipe of an engine in a high temperature region.
As shown in FIG. 1, the pressure sensor 10 includes a housing 20 that can be attached to a measurement pipe as a member to be attached, and a connector case 30 in which a pin-shaped terminal 31 is integrally formed by insert molding or the like. .

  The housing 20 is formed in a hollow shape from a metal such as stainless steel, for example, and a male screw portion 21 that can be fastened to the measurement pipe is formed on the outer peripheral surface of the lower portion of the housing 20. An opening 23 surrounded by the peripheral wall 22 is formed in the upper portion of the housing 20. Further, a pressure introducing hole 24 communicating with the opening 23 is formed on the lower surface of the housing 20, and when the housing 20 is fastened and fixed to the measurement pipe by the male screw portion 21, The detected medium flowing in the pipe is introduced into the pressure introducing hole 24.

  Three long slits 25 are formed on the outer periphery of the peripheral wall 22 of the housing 20. As a result, the surface area of the outer peripheral surface of the peripheral wall 22 is increased. The slit 25 is not limited to be formed in a long groove shape, and may be formed so that a plurality of concave groove portions are provided. Further, the slit 25 is not limited to three places, and may be formed at one place, two places, or four places or more.

  A metal stem 40 processed into a bottomed cylindrical shape is fixed to the upper portion of the pressure introducing hole 24 of the housing 20. The stem 40 is fixed by fastening a male screw portion 41 formed on the lower outer peripheral surface thereof and a female screw portion 24 a formed on the upper inner peripheral surface of the pressure introducing hole 24 of the housing 20.

  The stem 40 has a thin-walled diaphragm 42 that can be displaced by the pressure of the medium to be detected introduced through the pressure introduction hole 24 at an upper portion thereof, and an opening 43 that communicates with the diaphragm 42 at a lower portion thereof. Yes.

  When the stem 40 is fastened to the pressure introduction hole 24, the pressure introduction hole 24 and the opening 43 communicate with each other, and the detected medium is introduced into the diaphragm 42 through the pressure introduction hole 24 and the opening 43. Become.

  On the outer surface of the diaphragm 42, a sensor element 44 having a strain gauge or the like that outputs an electrical signal corresponding to the deformation of the diaphragm 42 is provided. When the diaphragm 42 is displaced by the pressure introduced into the opening 43 through the pressure introducing hole 24, the sensor element 44 converts a change in the resistance value of the strain gauge according to the displacement into an electric signal and outputs it. It functions as a detection unit.

  In the opening portion 23 of the housing 20, an annular substrate 50 that generates an output signal corresponding to an electrical signal from the sensor element 44 is disposed via an annular spacer 51. Specifically, the annular substrate 50 includes an IC chip having a signal conversion function, a signal processing circuit for processing an electrical signal input from the sensor element 44 and generating an output signal corresponding to the processing, a wiring pattern, and the like. It has a function as a circuit element provided with.

  The sensor element 44 and the annular substrate 50 are connected by a bonding wire 52 and are electrically connected, and a signal from the sensor element 44 is input to a circuit and an IC chip arranged on the annular substrate 50. ing.

  The annular spacer 51 is formed in an annular shape with a resin such as PPS (polyphenylene sulfide), and is disposed on the bottom wall of the opening 23 of the housing 20 so that the upper portion of the stem 40 is inserted into the inner peripheral hole thereof. . By arranging the annular substrate 50 on the annular spacer 51 formed in this way, the annular substrate 50 is brought close to the sensor element 44 on the diaphragm 42 of the stem 40.

  A seal material 53 such as silicone rubber is filled between the annular spacer 51 and the opening 23 and the stem 40. With this sealing material 53, the annular spacer 51 is fixed in the opening 23, and airtightness between the opening 23 and the pressure introducing hole 24 is ensured.

  The connector case 30 is formed of a material having a specific heat smaller than that of the housing 20 such as a synthetic resin. An upper opening 33 surrounded by a peripheral wall 32 is formed in the upper part of the connector case 30. One end of the terminal 31 protrudes into the upper opening 33.

  Two openings 34 and 35 are formed in the lower part of the connector case 30, and the other end of the terminal 31 is exposed in the opening 34.

  The opening 35 is provided with an internal pressure adjusting diaphragm 36 so as to seal the opening 35 against the lower surface of the connector case 30, and the internal pressure adjusting chamber Sa is defined by the opening 35 and the internal pressure adjusting diaphragm 36. Has been. The internal pressure adjusting diaphragm 36 is formed of, for example, a soft elastic body such as synthetic rubber, and is configured to be elastically deformed according to the pressure difference between the pressure in the internal pressure adjusting chamber Sa and the pressure outside the internal pressure adjusting chamber Sa. Has been. In addition, a communication hole 37 that communicates the opening 35 and the upper opening 33 is formed so that the pressure in the internal pressure adjusting chamber Sa becomes equal to the atmospheric pressure without changing according to the ambient temperature.

  The lower end portion of the connector case 30 configured in this manner is fitted to a cut portion 22 a formed on the inner peripheral surface of the peripheral wall 22 of the housing 20, and the distal end portion of the peripheral wall 22 of the housing 20 is connected to the outer wall of the connector case 30. The housing 20 and the connector case 30 are integrated by caulking. At that time, the circuit on the annular substrate 50 is electrically connected to one end side of the corresponding terminal 31 via the terminal 54 or the like. Then, the other end of the terminal 31 is connected to an external connector (not shown) or the like, thereby being electrically connected to an external counterpart circuit or the like via a wiring member. An O-ring 60 is disposed between the lower portion of the outer peripheral surface of the connector case 30 and the cut portion 22a of the housing 20 to ensure airtightness between them.

  Further, when the housing 20 and the connector case 30 are integrated as described above, a sealed space (hereinafter referred to as “the sealed wall”) defined by the inner peripheral surface of the peripheral wall 22 of the housing 20, the lower surface of the connector case 30, the stem 40, the annular substrate 50, and the like. The cooling liquid W is filled in the cooling chamber Sc). The coolant W is a fluorine-based liquid or a silicon-based liquid having a low viscosity and excellent insulating properties, and directly contacts the sensor element 44 on the diaphragm 42 of the stem 40 or the circuit on the annular substrate 50 to exchange heat. To play a role.

  The pressure sensor 10 configured in this manner is attached to a measurement pipe through which a medium to be detected flows to be in an operating state. When the medium to be detected is introduced into the opening 43 of the stem 40 through the pressure introducing hole 24 of the housing 20, the diaphragm 42 is deformed by the pressure of the medium to be detected. When a signal corresponding to the deformation of the diaphragm 42 is output from the sensor element 44 to the annular substrate 50, a signal processed by the circuit of the annular substrate 50 or the like is output to an external counterpart circuit or the like via the terminal 31 or the like. The

  At this time, since the medium to be detected and the measurement pipe through which the medium to be detected flow are at a high temperature, the housing 20 attached to the measurement pipe and the stem 40 fixed to the housing 20 are at a high temperature. On the other hand, since the connector case 30 is made of a resin having a small specific heat with respect to the housing 20, the heat of the housing 20 is difficult to be transmitted, so that the temperature is lower than that of the housing 20 and the stem 40.

  For this reason, the temperature of the coolant W in the vicinity of the housing 20 and the stem 40 (lower part of the cooling chamber Sc) is higher than the temperature of the coolant W in the vicinity of the connector case 30 (upper part of the cooling chamber Sc). Then, the coolant W having a high temperature in the lower portion of the cooling chamber Sc flows toward the upper portion of the cooling chamber Sc, and is cooled by exchanging heat with the connector case 30 and the like in the upper portion of the cooling chamber Sc. It flows toward. That is, due to a temperature difference between the housing 20 and the connector case 30 and the like, the coolant W convects in the cooling chamber Sc up and down.

  For this reason, the housing 20 is cooled by heat exchange between the housing 20 which is a high temperature part and the coolant W, and the coolant W itself is cooled by heat exchange between the connector case 30 which is a low temperature part and the coolant W.

  Further, heat is transmitted to the sensor element 44, the annular substrate 50, and the like from the housing 20, the stem 40, and the like that are high-temperature portions. At this time, since the sensor element 44 and the annular substrate 50 are disposed in the cooling chamber Sc in which the coolant W convects, heat is exchanged between the sensor element 44 and the annular substrate 50 and the coolant W. The sensor element 44 and the annular substrate 50 can be cooled.

  In particular, since the surface area of the outer peripheral surface of the peripheral wall 22 is increased by forming three slits 25 on the outer periphery of the peripheral wall 22 of the housing 20, the heat dissipation effect of the housing 20 is improved and the temperature of the coolant W is increased. Is suppressed.

  Further, when the coolant W filled in the cooling chamber Sc is thermally expanded, the internal pressure adjusting diaphragm 36 is elastically deformed so as to enter the opening 35 by the thermal expansion of the coolant W in the internal pressure adjusting chamber Sa. As a result, the cooling chamber Sc becomes wider. Thereby, the pressure of the coolant W in the cooling chamber Sc is kept constant. In particular, since the opening 35 communicates with the upper opening 33 through the communication hole 37, the pressure in the internal pressure adjusting chamber Sa is always equal to the atmospheric pressure without changing according to the ambient temperature. Will be adjusted.

  As described above, in the pressure sensor 10 according to the present embodiment, the inside of the cooling chamber Sc formed by assembling the housing 20 fixed to the measurement pipe and the connector case 30 having a specific heat smaller than that of the housing 20. In addition, the sensor element 44 and the annular substrate 50 are disposed and the coolant W is filled.

  When the detection medium and the measurement pipe through which the detection medium flows are at a high temperature, the housing 20 attached to the measurement pipe is at a high temperature, while the connector case 30 having a lower specific heat than the housing 20 is compared with the housing 20. Temperature decreases.

  For this reason, the cooling liquid W in the lower part of the cooling chamber Sc has a higher temperature than the cooling liquid W in the upper part of the cooling chamber Sc, and the cooling liquid W convects in the cooling chamber Sc. The housing 20 is cooled by heat exchange with the liquid W, and the coolant W itself is cooled by heat exchange between the connector case 30 which is a low temperature portion and the coolant W.

At this time, since the sensor element 44 and the annular substrate 50 are disposed in the cooling chamber Sc in which the coolant W convects, heat is exchanged between the sensor element 44 and the annular substrate 50 and the coolant W, and the sensor The element 44 and the annular substrate 50 can be cooled. In particular, since the sensor element 44 and the annular substrate 50 are cooled, the heat resistance of other peripheral elements is increased as compared with the case where a sensor element or a substrate with improved heat resistance for use in a high temperature region is employed. It is not necessary, and an increase in manufacturing cost related to heat resistance can be suppressed.
Therefore, the pressure sensor 10 configured as described above can be used even in a high temperature region.

  In the pressure sensor 10 according to this embodiment, three slits 25 are formed on the outer periphery of the outer wall 22 of the housing 20. Thereby, since the surface area of the outer periphery of the housing 20 becomes large, the heat dissipation effect of the housing 20 can be enhanced. As a result, since the temperature rise of the cooling liquid W is suppressed, the cooling effect of the sensor element 44 and the annular substrate 50 can be improved.

  Further, in the pressure sensor 10 according to the present embodiment, the connector case 30 is formed with an internal pressure adjusting chamber Sa partitioned by an internal pressure adjusting diaphragm 36 with respect to the cooling chamber Sc. Accordingly, the cooling chamber Sc is widened by elastically deforming the inner pressure adjusting diaphragm 36 so as to enter the inner pressure adjusting chamber Sa according to the thermal expansion of the coolant W. As a result, since the pressure of the coolant W in the cooling chamber Sc is kept constant, it is possible to suppress the pressure caused by the thermal expansion of the coolant W from affecting the displacement of the diaphragm 42 of the stem 40.

  Furthermore, in the pressure sensor 10 according to the present embodiment, the connector case 30 is formed with a communication hole 37 that allows the internal pressure adjusting chamber Sa to communicate with the atmosphere. Thereby, the pressure of the internal pressure adjusting chamber Sa is adjusted so as to be always equal to the atmospheric pressure without changing according to the ambient temperature, so that the influence of the thermal expansion of the cooling liquid W in the cooling chamber Sc can be reliably suppressed. Can do.

In addition, this invention is not limited to the said embodiment, You may actualize as follows, and even in that case, an effect | action and effect equivalent to the said embodiment are acquired.
(1) FIG. 2 is a cross-sectional view showing a schematic configuration of the pressure sensor 10 in the first modification.
As shown in FIG. 2, in the housing 20 described above, a plurality of fins 26 protruding outward from the outer peripheral surface of the peripheral wall 22 may be provided instead of the long groove-shaped slit 25 provided on the outer periphery of the peripheral wall 22. Good. Even in this case, the surface area of the outer periphery of the housing 20 can be increased. Further, the outer peripheral surface of the peripheral wall 22 may be formed in a mesh shape to increase the surface area.

(2) FIG. 3 is a cross-sectional view showing a schematic configuration of the pressure sensor 10 in the second modification.
As shown in FIG. 3, in the housing 20 described above, instead of the long groove-like slit 25 provided on the outer periphery of the peripheral wall 22, a protrusion that protrudes in a convex shape long in the vertical direction inward from the inner peripheral surface of the peripheral wall 22. A plurality of portions 27 may be provided. Thereby, since the surface area of the inner periphery of the housing 20 is increased, heat exchange between the housing 20 and the coolant W can be promoted. As a result, the cooling effect of the housing 20 is improved, so that the temperature rise of the sensor element 44 and the annular substrate 50 due to heat transfer from the housing 20 can be suppressed. Further, the surface area may be increased by forming one or a plurality of concave grooves on the inner peripheral surface of the peripheral wall 22.

(3) FIG. 4 is a cross-sectional view showing a schematic configuration of the pressure sensor 10 in the third modification.
As shown in FIG. 4, in the housing 20 described above, a plurality of the protruding portions 27 described above may be provided in addition to the long groove-shaped slits 25 provided on the outer periphery of the peripheral wall 22. Thereby, since the surface area of the outer periphery and the inner periphery of the housing 20 is increased, the heat dissipation effect of the housing 20 can be enhanced and heat exchange between the housing 20 and the coolant W can be promoted.

It is sectional drawing which shows the structure outline | summary of the pressure sensor which concerns on this embodiment. It is sectional drawing which shows the structure outline | summary of the pressure sensor in a 1st modification. It is sectional drawing which shows the structure outline | summary of the pressure sensor in a 2nd modification. It is sectional drawing which shows the structure outline | summary of the pressure sensor in a 3rd modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Pressure sensor 20 ... Housing 22 ... Peripheral wall 24 ... Pressure introduction hole (introduction hole)
DESCRIPTION OF SYMBOLS 25 ... Slit 26 ... Fin 27 ... Projection part 30 ... Connector case 31 ... Terminal 35 ... Opening part 36 ... Internal pressure adjustment diaphragm 37 ... Communication hole 40 ... Stem 42 ... Diaphragm 44 ... Sensor element 50 ... Annular substrate (circuit element)
Sa ... Internal pressure adjustment chamber (Internal pressure adjustment space)
Sc ... Cooling room (sealed space)
W ... Coolant (insulating liquid)

Claims (8)

A housing that can be attached to an attachment member through which a medium to be detected flows, and in which an introduction hole for introducing the medium to be detected is formed;
A connector case having a terminal for exchanging signals with the outside and having a specific heat smaller than that of the housing; and
A diaphragm that is displaced according to a detected pressure of the detected medium introduced through the introduction hole;
A sensor element for detecting the detected pressure based on the displacement of the diaphragm;
A sealed space formed by assembling the housing and the connector case, the sealed space in which the sensor element is disposed;
An insulating liquid filled in the sealed space;
A pressure sensor comprising: A circuit element that processes a signal output from the sensor element and outputs the signal to the outside via the terminal,
The pressure sensor according to claim 1, wherein the circuit element is disposed in the sealed space.   The pressure sensor according to claim 1 or 2, wherein one or a plurality of concave grooves are formed on an outer periphery of the housing.   The pressure sensor according to claim 1 or 2, wherein one or a plurality of convex protrusions are formed on an outer periphery of the housing.   The pressure sensor according to any one of claims 1 to 4, wherein one or a plurality of concave grooves are formed on an inner periphery of the housing constituting the sealed space.   The pressure sensor according to any one of claims 1 to 4, wherein one or a plurality of convex protrusions are formed on an inner periphery of the housing constituting the sealed space.   The pressure sensor according to any one of claims 1 to 6, wherein an internal pressure adjusting space defined by an elastic film is formed in the connector case with respect to the sealed space.   The pressure sensor according to claim 7, wherein the connector case includes a communication hole that communicates the internal pressure adjustment space with the atmosphere.

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