CA1152180A - Pressure transducer - Google Patents
Pressure transducerInfo
- Publication number
- CA1152180A CA1152180A CA000345064A CA345064A CA1152180A CA 1152180 A CA1152180 A CA 1152180A CA 000345064 A CA000345064 A CA 000345064A CA 345064 A CA345064 A CA 345064A CA 1152180 A CA1152180 A CA 1152180A
- Authority
- CA
- Canada
- Prior art keywords
- pressure
- terminals
- closed housing
- casing
- plug
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
- G01L19/14—Housings
- G01L19/147—Details about the mounting of the sensor to support or covering means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
- G01L19/0007—Fluidic connecting means
- G01L19/0038—Fluidic connecting means being part of the housing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
- G01L19/0061—Electrical connection means
- G01L19/0084—Electrical connection means to the outside of the housing
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
- G01L19/06—Means for preventing overload or deleterious influence of the measured medium on the measuring device or vice versa
- G01L19/0627—Protection against aggressive medium in general
- G01L19/0654—Protection against aggressive medium in general against moisture or humidity
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
- G01L19/14—Housings
- G01L19/142—Multiple part housings
- G01L19/143—Two part housings
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
- G01L19/14—Housings
- G01L19/148—Details about the circuit board integration, e.g. integrated with the diaphragm surface or encapsulation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L23/00—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid
- G01L23/24—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid specially adapted for measuring pressure in inlet or exhaust ducts of internal-combustion engines
Abstract
PRESSURE TRANSDUCER
Abstract of the Disclosure The invention concerns a pressure transducer for automobiles including a closed housing, means for detect-ing the pressure in a suction pipe of an engine and for converting the pressure detected into electric signals, an amplification circuit disposed in the closed housing, and air passages. The air passages communicate with the atmosphere, and prevent water from penetrating therethrough into the closed housing. The air passages include an air hole formed in a member defining the closed housing about terminals provided for leading the electric signals out of the closed housing. In this way, the pressure trans-ducer can be mounted directly within an automobile engine without loss of performance due to water contamination.
Abstract of the Disclosure The invention concerns a pressure transducer for automobiles including a closed housing, means for detect-ing the pressure in a suction pipe of an engine and for converting the pressure detected into electric signals, an amplification circuit disposed in the closed housing, and air passages. The air passages communicate with the atmosphere, and prevent water from penetrating therethrough into the closed housing. The air passages include an air hole formed in a member defining the closed housing about terminals provided for leading the electric signals out of the closed housing. In this way, the pressure trans-ducer can be mounted directly within an automobile engine without loss of performance due to water contamination.
Description
This invention relates to a pressure transducer suitable for use as a pressure detector for automobiles.
Pressure transducers are widely used ln automobiles.
The following uses are given as examples. They are used for maintaining the most suitable combustion condition of an engine by controlling the amount of fuel injected by an electronic fuel injector and the advance angle of an electronic angle-advancing device, by means of electric signals obtained by detecting the pressure difference between the pressure in the suction pipe of the engine and atmospheric pressure or absolute pressure. They are also used for compensating for altitude by detecting atmospheric pressure changes, and a method for indicating the pressure in the suction pipe of an engine to the driver, etc.
Hitherto, a Bourdon-tube pressure gauge has been used as a means for indicating the suction pipe pressure of an engine of a car to the driver operating the car. In such a case, the gauge is located within the passenger compart-ment of the car, and the pressure in the suction pipe is supplied from the engine to the gauge through a pressure induction pipe. In such an arrangement of the pressure gauge, if the induction pipe becomes disengaged from the - pressure gauge, non-combustion gases and combustion sases for EGR (exhaust gas recirculation~ enter the passenger compartment o~ the car, thus endangering the driver and passengers. Therefore, it has been proposed to provide a mere indication device in the passenger compartment, and to provide a pressure detector in the engine which trans-mits electrical signals to the indication device on which the pressure in the suction pipe is displayed.
When a pressure detector such as a pressure transducer q~
21~(~
is disposed in the engine, particularly when an amplifier is incorporated within the pressure detector to amplify the electrical signals generated by pressure differences, it is necessary for the pressure detector to be waterproof, because changes in the characteristics of the pressure detector, diminished conductivity, etc. due to rust may occur. On the other hand, if the pressure detector is made completely airtight as shown in Figures 2, 6, 7 of :.5. patent 3,568,124, the reference pressure in the airtight chamber changes with temperature, therefore the precision or performance of the pressure detector is greatly reduced.
An object of the invention is to provide a pressure transducer which is able to prevent water from penetrating into the interior of the pressure transducer and to maintain the reference pressure substantially constant, irrespective of the change of temperature in the surroundings.
According to the inventon there is provided a pressure transducer for automobiles comprising a closed housing means including a pressure sensing means, means for communicating pressure to be sensed to said pressure sensing means, means disposed in the closed housing means for converting the pressure sensed by the pressure sensing means into electric energy, terminals electrically connected to said means for converting pressure into electric energy and partially disposed out of said closed housing means, an air hole in said closed housing means for passing air therethrough so that the interior of said closed housing means communicates with the atmosphere, whereby the reference pressure in the interior of said 18~
closed housing means is kept substantially constant, a cylindrical wall on the ex~erior of said closed housing means surrounding said terminals disposed out of said closed housing means and also surrounding said air hole, and a plug having therein outer terminals and lead wires electrically connected to said outer terminals, said plug being shaped to fit within said cylindrical wall while leaving small gaps between said plug and said walls so that said terminals contact with said outer terminals, wherein said plug and said cylindrical walls shield said air hole to substantially prevent penetration of water into said closed housing means while allowing atmospheric air to reach said air hole by virtue of said small gaps.
An advantage of the invention, at least in preferred - 2a -21~30 forms, is that it can provide a waterproof pressure transducer which is of high quality and reliability, and can detect peessure with accuracy.
Another object of the invention, at least in preferred forms, is that it can provide a waterproof pressure trans-ducer which can be disposed in the engine of an automobile and can precisely detect the pressure in the suction pipe of the engine.
The air passage means can cause the closed chamber of the pressure transducer therein containing means for con-verting the pressure detected into electric signals to communicate with the atmosphere, and prevent water from penetrating into the closed chamber.
The air passage means, for example, comprises an air hole provided in a casing defining the closed chamber about the portion where terminals electrically connected to the converting means are exposed outside the closed chamber. The air hole communicates with the atmosphere through a plurality of gaps defined by the casing, a plug with outer terminals inserted to contact the abovemen-tioned terminals with the outer terminals provided, and the terminals, so that the closed chamber can communicate with the atmosphere through the-complicated air passage.
The invention will be described in further detail with reference to the accompanying drawings, in which:-Figure 1 is a sectional view of an embodiment of apressure transducer according to the invention;
Figure 2 is a sectional view of a part of the pressure transducer shown in Figure 1 and a plug inserted into the casing of the pressure transducer; and Figure 3 is a sectional view of another embodiment of a pressure transducer according to the invention.
An embodiment of a pressure transducer for automobiles according to the invention will be described hereinafter in detail with reference to the drawings.
In Figure 1 showing a section of a pressure transducer for automobiles, a casing 3 is made of resin, and has a bottom portion 301 and a side wall portion 302. An open end 303 of the casing 3 is closed and made airtight by a cover 4 and an O-ring 6 so that a closed chamber 8 is formed. The bottom portion 301 has a hole 304 in which a glass support 5 is inserted and secured in an airtight manner to the casing 3 by bonding means 7. The glass support 5 has an axially extending hole 10 which communi-cates with a hole 305 made in the bottom 301 of the casing 3, thereby providing a pressure induction passage. A
silicon diaphragm 9 is joined onto the glass support 5 so as to be subjected to the pressure in the pressure induction passage. Diffused resistances 11 and electrodes 13 are formed on the diaphragm 9.
A ceramic base plate 15 is joined onto the bottom portion 301 of the casing 3. An operational amplifier 17 is integrated onto the ceramic base plate 15 and electrically connected to the diffused resistances 11 through lead wires 19 so that electrical energy or electrical signals into which the detected pressure is converted are amplified. The electrical signals thereby produced are led to a pair of terminals 21 which are each inserted into the bottom portion 301 of the casing 3, and partially disposed outside the casing 3. The portions of the terminals 21 disposed outside are surrounded by a cylindrical projection 23 which is constructed so as to form a coupler in cooperation with a plug 25, shown in Figure 2.
A fine vent hole 27 is formed in the bottom portion 301 near the terminals 21, preferably between the termi-nals 21 as shown. The plug 25 has a pair of female outer terminals 29 which are connected to a pair of lead wires 31 coated with insulating material. When the plug 25 is inserted into the projection 23, the terminals 21 are inserted in the female outer terminals 29. In this condition, the air vent hole 27 communicates with the atmosphere through an expanded air passage or space 33 defined by the casing 3 and the plug 25 and a plurality of fine air passages or gaps 35 defined between the projection 23 and the plug 25 and gaps 37 between the terminals 21 and the female terminals 29.
A flexible cover 39 made of a resilient material e.g.
rubber is provided on the coupler portion, and one end 38 forms an airtight seal around the projection 23, and the other 40 is mounted on the palr of lead wires 31. Fine air passages are formed between the cover 39 and the adja-cent portions 42 of the pair of lead wires 31, so that the interior of the cover 39 communicates therethrough with the atmosphere. Therefore, when the resilient cover 39 is provided, the above-mentioned air passage means further includes the fine air passages 41.
When the pressure transducer is used for detecting the pressure in the suction pipe of an engine, the pressure transducer can be located in the engine (not shown) of an automobile, with the pressure induction passage 305 communicating with the suction pipe (not shown) of the engine. The lead wires 31 are electrically connected to a pressure indicator (not shown) disposed in the passenger compartment of the automobile.
When the pressure in the suction pipe of the engine acts upon the silicon diaphragm 9, the pressure differ-ence between that pressure and the reference pressure or atmospheric pressure in the closed chamber 8 is detected and electric signals are produced by the piezoresistance effects of the silicon diaphragm 9, the electrical signals are amplified by the operational amplifier 17, and trans-mitted to the pressure indicator through the terminals 21, the outer terminals 29, and the lead wires 31, whereby the driver operating the engine in the passenger compartment of the car is informed of the pressure in the suction pipe of the engine.
If the temperature in the surroundings of the trans-ducer changes, the volume of air in the closed chamber 8 changes, so that the air or other atmosphere flows out of or into the closed chamber 8 through the air passage means, that is, through the air vent hole 27, the space 33, the gaps 35, 37 and the fine air passage 41, so that the reference pressure is kept substantially constant.
Water in the surroundings of the pressure transducer is prevented from penetrating into the closed chamber 8 through the air passage means, because the air passage means comprises the air vent hole 27 disposed near the terminals 21, and direct communication between the closed chamber 8 and the atmosphere by the air vent hole 27 can be prevented by the plug 25 located the cylindrical projection 23. When the plug 25 is inserted, the air passage means comprises, in addition to the air vent hole 27, the gaps 35 between the projection 23 and the plug ~2~
25, the gaps 37 between the terminals 21 and the outer terminals 29, and the fine air passage formed between the pair of lead wires 31 and the cover 39. Therefore, the air passage means is a complicated arrangement of fine passageways so that it is difficult for water to penetrate into the closed chamber 8. Further, the air passage means includes the space 35, so that the sectional area of the air passage means changes greatly from the air vent hole 27 toward the fine air passage 41. Therefore, it is very ]o difficult for water to penetrate into the closed chamber 8. Further, the air vent hole 27 is disposed under the bottom face 306 of the closed chamber 8, so that water is further inhibited from penetrating into the closed chamber 8.
Thus, in this embodiment of the pressure transducer, changes of the reference pressure due to change of the surrounding temperature can be prevented while also preventing water from penetrating into the closed chamber -: 8, so that the pressure transducer has good performance and reliability. Further, the pressure transducer can be installed in ~he engine itself. Therefore, even if posi-tive pressure is applied, for example, in the suction pipe of a turbocharged car engine so tha~ a pressure induction passage is disengaged, the driver in the passenger compart-ment cannot be harmed. Additionally, the cylindrical projection 23 is provided on the casing 3 as a unitary piece. Therefore, the terminals 21 can be inserted securely into the outer terminals 27.
Another embodiment of a pressure transducer for auto-mobiles will be explained referring to Figure 3. Thisembodiment differs from the above-mentioned embodiment only in that a casing 3A has a cylindrical boss 50 and that a sealing member 51 is provided on the air vent hole 27. The other construction is the same as the construc-- tion shown in Figure 1 so that detailed explanation is not necessary.
In Figure 3, an air vent hole 27a is made in the bottom 301 and the boss 50 oE the casing 3A so that the air passage of the air vent hole 27a is longer than the air vent hole 27 of the previous embodiment. The sealing member 51 is porous and non wettable, and it is disposed on the bottom portion 301 of the casing 3A so that air in the closed chamber 8 passes through the sealing member 51, and the air vent hole 27a. Unwoven cloth and sponge having continuous air holes are examples of the materials useful as the sealing member 51. When coated with silicon resin, the non-wettability of these materials is further increased.
In this embodiment, when the temperature in the surroundings changes, the air in the closed chamber 8 or the atmosphere in the surroundings of the transducer flows out of or into the closed chamber 8 through the sealing member 51, air vent hole 27a, so that the reference pressure is kept substantially constant. Water pene-tration into the closed chamber 8 is prevented by the elongated air vent 27a, and the sealing member 51. The cylindrical boss 50 prevents water on the outer surface of the casing 3A from penetrating into the air vent hole 27a by spreading of water on the surface 307.
When the plug 25 is inserted into the cylindrical projection 23, the space 33, the gaps 35, 37 and the fine air passage 41 are formed in the same manner as the embodiment in Figures 1, 2 so that water proofing is further increased.
Pressure transducers are widely used ln automobiles.
The following uses are given as examples. They are used for maintaining the most suitable combustion condition of an engine by controlling the amount of fuel injected by an electronic fuel injector and the advance angle of an electronic angle-advancing device, by means of electric signals obtained by detecting the pressure difference between the pressure in the suction pipe of the engine and atmospheric pressure or absolute pressure. They are also used for compensating for altitude by detecting atmospheric pressure changes, and a method for indicating the pressure in the suction pipe of an engine to the driver, etc.
Hitherto, a Bourdon-tube pressure gauge has been used as a means for indicating the suction pipe pressure of an engine of a car to the driver operating the car. In such a case, the gauge is located within the passenger compart-ment of the car, and the pressure in the suction pipe is supplied from the engine to the gauge through a pressure induction pipe. In such an arrangement of the pressure gauge, if the induction pipe becomes disengaged from the - pressure gauge, non-combustion gases and combustion sases for EGR (exhaust gas recirculation~ enter the passenger compartment o~ the car, thus endangering the driver and passengers. Therefore, it has been proposed to provide a mere indication device in the passenger compartment, and to provide a pressure detector in the engine which trans-mits electrical signals to the indication device on which the pressure in the suction pipe is displayed.
When a pressure detector such as a pressure transducer q~
21~(~
is disposed in the engine, particularly when an amplifier is incorporated within the pressure detector to amplify the electrical signals generated by pressure differences, it is necessary for the pressure detector to be waterproof, because changes in the characteristics of the pressure detector, diminished conductivity, etc. due to rust may occur. On the other hand, if the pressure detector is made completely airtight as shown in Figures 2, 6, 7 of :.5. patent 3,568,124, the reference pressure in the airtight chamber changes with temperature, therefore the precision or performance of the pressure detector is greatly reduced.
An object of the invention is to provide a pressure transducer which is able to prevent water from penetrating into the interior of the pressure transducer and to maintain the reference pressure substantially constant, irrespective of the change of temperature in the surroundings.
According to the inventon there is provided a pressure transducer for automobiles comprising a closed housing means including a pressure sensing means, means for communicating pressure to be sensed to said pressure sensing means, means disposed in the closed housing means for converting the pressure sensed by the pressure sensing means into electric energy, terminals electrically connected to said means for converting pressure into electric energy and partially disposed out of said closed housing means, an air hole in said closed housing means for passing air therethrough so that the interior of said closed housing means communicates with the atmosphere, whereby the reference pressure in the interior of said 18~
closed housing means is kept substantially constant, a cylindrical wall on the ex~erior of said closed housing means surrounding said terminals disposed out of said closed housing means and also surrounding said air hole, and a plug having therein outer terminals and lead wires electrically connected to said outer terminals, said plug being shaped to fit within said cylindrical wall while leaving small gaps between said plug and said walls so that said terminals contact with said outer terminals, wherein said plug and said cylindrical walls shield said air hole to substantially prevent penetration of water into said closed housing means while allowing atmospheric air to reach said air hole by virtue of said small gaps.
An advantage of the invention, at least in preferred - 2a -21~30 forms, is that it can provide a waterproof pressure transducer which is of high quality and reliability, and can detect peessure with accuracy.
Another object of the invention, at least in preferred forms, is that it can provide a waterproof pressure trans-ducer which can be disposed in the engine of an automobile and can precisely detect the pressure in the suction pipe of the engine.
The air passage means can cause the closed chamber of the pressure transducer therein containing means for con-verting the pressure detected into electric signals to communicate with the atmosphere, and prevent water from penetrating into the closed chamber.
The air passage means, for example, comprises an air hole provided in a casing defining the closed chamber about the portion where terminals electrically connected to the converting means are exposed outside the closed chamber. The air hole communicates with the atmosphere through a plurality of gaps defined by the casing, a plug with outer terminals inserted to contact the abovemen-tioned terminals with the outer terminals provided, and the terminals, so that the closed chamber can communicate with the atmosphere through the-complicated air passage.
The invention will be described in further detail with reference to the accompanying drawings, in which:-Figure 1 is a sectional view of an embodiment of apressure transducer according to the invention;
Figure 2 is a sectional view of a part of the pressure transducer shown in Figure 1 and a plug inserted into the casing of the pressure transducer; and Figure 3 is a sectional view of another embodiment of a pressure transducer according to the invention.
An embodiment of a pressure transducer for automobiles according to the invention will be described hereinafter in detail with reference to the drawings.
In Figure 1 showing a section of a pressure transducer for automobiles, a casing 3 is made of resin, and has a bottom portion 301 and a side wall portion 302. An open end 303 of the casing 3 is closed and made airtight by a cover 4 and an O-ring 6 so that a closed chamber 8 is formed. The bottom portion 301 has a hole 304 in which a glass support 5 is inserted and secured in an airtight manner to the casing 3 by bonding means 7. The glass support 5 has an axially extending hole 10 which communi-cates with a hole 305 made in the bottom 301 of the casing 3, thereby providing a pressure induction passage. A
silicon diaphragm 9 is joined onto the glass support 5 so as to be subjected to the pressure in the pressure induction passage. Diffused resistances 11 and electrodes 13 are formed on the diaphragm 9.
A ceramic base plate 15 is joined onto the bottom portion 301 of the casing 3. An operational amplifier 17 is integrated onto the ceramic base plate 15 and electrically connected to the diffused resistances 11 through lead wires 19 so that electrical energy or electrical signals into which the detected pressure is converted are amplified. The electrical signals thereby produced are led to a pair of terminals 21 which are each inserted into the bottom portion 301 of the casing 3, and partially disposed outside the casing 3. The portions of the terminals 21 disposed outside are surrounded by a cylindrical projection 23 which is constructed so as to form a coupler in cooperation with a plug 25, shown in Figure 2.
A fine vent hole 27 is formed in the bottom portion 301 near the terminals 21, preferably between the termi-nals 21 as shown. The plug 25 has a pair of female outer terminals 29 which are connected to a pair of lead wires 31 coated with insulating material. When the plug 25 is inserted into the projection 23, the terminals 21 are inserted in the female outer terminals 29. In this condition, the air vent hole 27 communicates with the atmosphere through an expanded air passage or space 33 defined by the casing 3 and the plug 25 and a plurality of fine air passages or gaps 35 defined between the projection 23 and the plug 25 and gaps 37 between the terminals 21 and the female terminals 29.
A flexible cover 39 made of a resilient material e.g.
rubber is provided on the coupler portion, and one end 38 forms an airtight seal around the projection 23, and the other 40 is mounted on the palr of lead wires 31. Fine air passages are formed between the cover 39 and the adja-cent portions 42 of the pair of lead wires 31, so that the interior of the cover 39 communicates therethrough with the atmosphere. Therefore, when the resilient cover 39 is provided, the above-mentioned air passage means further includes the fine air passages 41.
When the pressure transducer is used for detecting the pressure in the suction pipe of an engine, the pressure transducer can be located in the engine (not shown) of an automobile, with the pressure induction passage 305 communicating with the suction pipe (not shown) of the engine. The lead wires 31 are electrically connected to a pressure indicator (not shown) disposed in the passenger compartment of the automobile.
When the pressure in the suction pipe of the engine acts upon the silicon diaphragm 9, the pressure differ-ence between that pressure and the reference pressure or atmospheric pressure in the closed chamber 8 is detected and electric signals are produced by the piezoresistance effects of the silicon diaphragm 9, the electrical signals are amplified by the operational amplifier 17, and trans-mitted to the pressure indicator through the terminals 21, the outer terminals 29, and the lead wires 31, whereby the driver operating the engine in the passenger compartment of the car is informed of the pressure in the suction pipe of the engine.
If the temperature in the surroundings of the trans-ducer changes, the volume of air in the closed chamber 8 changes, so that the air or other atmosphere flows out of or into the closed chamber 8 through the air passage means, that is, through the air vent hole 27, the space 33, the gaps 35, 37 and the fine air passage 41, so that the reference pressure is kept substantially constant.
Water in the surroundings of the pressure transducer is prevented from penetrating into the closed chamber 8 through the air passage means, because the air passage means comprises the air vent hole 27 disposed near the terminals 21, and direct communication between the closed chamber 8 and the atmosphere by the air vent hole 27 can be prevented by the plug 25 located the cylindrical projection 23. When the plug 25 is inserted, the air passage means comprises, in addition to the air vent hole 27, the gaps 35 between the projection 23 and the plug ~2~
25, the gaps 37 between the terminals 21 and the outer terminals 29, and the fine air passage formed between the pair of lead wires 31 and the cover 39. Therefore, the air passage means is a complicated arrangement of fine passageways so that it is difficult for water to penetrate into the closed chamber 8. Further, the air passage means includes the space 35, so that the sectional area of the air passage means changes greatly from the air vent hole 27 toward the fine air passage 41. Therefore, it is very ]o difficult for water to penetrate into the closed chamber 8. Further, the air vent hole 27 is disposed under the bottom face 306 of the closed chamber 8, so that water is further inhibited from penetrating into the closed chamber 8.
Thus, in this embodiment of the pressure transducer, changes of the reference pressure due to change of the surrounding temperature can be prevented while also preventing water from penetrating into the closed chamber -: 8, so that the pressure transducer has good performance and reliability. Further, the pressure transducer can be installed in ~he engine itself. Therefore, even if posi-tive pressure is applied, for example, in the suction pipe of a turbocharged car engine so tha~ a pressure induction passage is disengaged, the driver in the passenger compart-ment cannot be harmed. Additionally, the cylindrical projection 23 is provided on the casing 3 as a unitary piece. Therefore, the terminals 21 can be inserted securely into the outer terminals 27.
Another embodiment of a pressure transducer for auto-mobiles will be explained referring to Figure 3. Thisembodiment differs from the above-mentioned embodiment only in that a casing 3A has a cylindrical boss 50 and that a sealing member 51 is provided on the air vent hole 27. The other construction is the same as the construc-- tion shown in Figure 1 so that detailed explanation is not necessary.
In Figure 3, an air vent hole 27a is made in the bottom 301 and the boss 50 oE the casing 3A so that the air passage of the air vent hole 27a is longer than the air vent hole 27 of the previous embodiment. The sealing member 51 is porous and non wettable, and it is disposed on the bottom portion 301 of the casing 3A so that air in the closed chamber 8 passes through the sealing member 51, and the air vent hole 27a. Unwoven cloth and sponge having continuous air holes are examples of the materials useful as the sealing member 51. When coated with silicon resin, the non-wettability of these materials is further increased.
In this embodiment, when the temperature in the surroundings changes, the air in the closed chamber 8 or the atmosphere in the surroundings of the transducer flows out of or into the closed chamber 8 through the sealing member 51, air vent hole 27a, so that the reference pressure is kept substantially constant. Water pene-tration into the closed chamber 8 is prevented by the elongated air vent 27a, and the sealing member 51. The cylindrical boss 50 prevents water on the outer surface of the casing 3A from penetrating into the air vent hole 27a by spreading of water on the surface 307.
When the plug 25 is inserted into the cylindrical projection 23, the space 33, the gaps 35, 37 and the fine air passage 41 are formed in the same manner as the embodiment in Figures 1, 2 so that water proofing is further increased.
Claims (5)
1. A pressure transducer for automobiles comprising a closed housing means including a pressure sensing means, means for communicating pressure to be sensed to said pressure sensing means, means disposed in the closed housing means for converting the pressure sensed by the pressure sensing means into electric energy, terminals electrically connected to said means for converting pressure into electric energy and partially disposed out of said closed housing means, an air hole in said closed housing means for passing air therethrough so that the interior of said closed housing means communicates with the atmosphere, whereby the reference pressure in the interior of said closed housing means is kept substantially constant, a cylindrical wall on the exterior of said closed housing means surrounding said terminals disposed out of said closed housing means and also surrounding said air hole, and a plug having therein outer terminals and lead wires electrically connected to said outer terminals, said plug being shaped to fit within said cylindrical wall while leaving small gaps between said plug and said walls so that said terminals contact with said outer terminals, wherein said plug and said cylindrical walls shield said air hole to substantially prevent penetration of water into said closed housing means while allowing atmospheric air to reach said air hole by virtue of said small gaps.
2. A pressure transducer for automobiles comprising:
a casing having a bottom portion, a side wall extending generally perpendicularly to said bottom portion to form an open end;
means for closing said open end airtightly thereby to provide a closed chamber;
means mounted in said casing for receiving pressure to be detected and converting the pressure into electric signals;
means disposed in said closed chamber for amplifying electric signals;
terminals electrically connected to said amplifying means and partially inserted in said bottom portion of said casing so that one end of said terminals are disposed out of said closed chamber;
air passage means formed in said casing about the positions of said terminals, said passage means communicating with the atmosphere and preventing water from penetrating into said closed chamber;
a cylindrical projection projecting from said bottom portion of said casing so as to surround said terminals and said air passage; and a plug having therein outer terminals and lead wires electrically connected to said outer terminals and inserted in said cylindrical projection so that said terminals contact with said outer terminals, wherein said air passage comprises an air hole made in said bottom portion of said casing, and said air hole communicates with a space defined by said cylindrical wall, gaps between said cylindrical wall and said plug and gaps between said terminals and said outer terminals.
a casing having a bottom portion, a side wall extending generally perpendicularly to said bottom portion to form an open end;
means for closing said open end airtightly thereby to provide a closed chamber;
means mounted in said casing for receiving pressure to be detected and converting the pressure into electric signals;
means disposed in said closed chamber for amplifying electric signals;
terminals electrically connected to said amplifying means and partially inserted in said bottom portion of said casing so that one end of said terminals are disposed out of said closed chamber;
air passage means formed in said casing about the positions of said terminals, said passage means communicating with the atmosphere and preventing water from penetrating into said closed chamber;
a cylindrical projection projecting from said bottom portion of said casing so as to surround said terminals and said air passage; and a plug having therein outer terminals and lead wires electrically connected to said outer terminals and inserted in said cylindrical projection so that said terminals contact with said outer terminals, wherein said air passage comprises an air hole made in said bottom portion of said casing, and said air hole communicates with a space defined by said cylindrical wall, gaps between said cylindrical wall and said plug and gaps between said terminals and said outer terminals.
3. The pressure transducer for automobiles as defined in claim 2, further including a flexible cover provided over said cylindrical projection, said plug, and said lead wire near said plug for preventing water from contacting these elements, wherein said air passage means further includes gaps defined between said cover and said lead wires.
4. The pressure transducer for automobiles as defined in claim 2 or 3 wherein a member is disposed in said air passage, said member having a plurality of fine air passages and a property of non wettability.
5. The pressure transducer for automobiles as defined in claim 2, wherein said air passage means includes a cylindrical boss defining a part of said air hole provided in said bottom portion of said casing, said cylindrical boss projecting slightly from said bottom portion of said casing within said projection surrounding said terminals.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1144979A JPS55103438A (en) | 1979-02-05 | 1979-02-05 | Pressure converter |
| JP11449/1979 | 1979-02-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1152180A true CA1152180A (en) | 1983-08-16 |
Family
ID=11778395
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000345064A Expired CA1152180A (en) | 1979-02-05 | 1980-02-05 | Pressure transducer |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4325260A (en) |
| EP (1) | EP0014452B1 (en) |
| JP (1) | JPS55103438A (en) |
| AU (1) | AU531193B2 (en) |
| CA (1) | CA1152180A (en) |
| DE (1) | DE3061837D1 (en) |
Families Citing this family (24)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57169644A (en) * | 1981-04-14 | 1982-10-19 | Nippon Denso Co Ltd | Semiconductor type pressure sensor |
| US4414851A (en) * | 1981-08-28 | 1983-11-15 | Motorola, Inc. | Gauge pressure sensor |
| JPS59142744U (en) * | 1983-03-15 | 1984-09-25 | 三菱電機株式会社 | electronic circuit housing |
| JPH0761031B2 (en) * | 1984-09-07 | 1995-06-28 | 株式会社日立製作所 | Digital automatic hybrid circuit |
| ATE35321T1 (en) * | 1985-01-28 | 1988-07-15 | Kristal Instr Ag | TRANSDUCER INSERT, PROCESS FOR ITS MANUFACTURE AND USE IN A TRANSDUCER FOR MEASUREMENT OF MECHANICAL QUANTITIES. |
| DE3784063T2 (en) * | 1987-05-27 | 1993-07-15 | Smc Corp | PRESSURE MEASURING DEVICE. |
| FI81911C (en) * | 1987-12-07 | 1990-12-10 | Vaisala Oy | TRYCKSAENDARE. |
| US4797007A (en) * | 1987-12-18 | 1989-01-10 | Emhart Industries, Inc. | Temperature and line pressure probe |
| US5049421A (en) * | 1989-01-30 | 1991-09-17 | Dresser Industries, Inc. | Transducer glass bonding technique |
| DE3919059A1 (en) * | 1989-06-10 | 1991-01-03 | Bosch Gmbh Robert | Pressure sensor esp. for vehicle engine compartment - has sensor resistances on membrane in sensor substrate base body |
| DE3937573A1 (en) * | 1989-11-11 | 1991-05-16 | Gewerk Eisenhuette Westfalia | ELECTRICAL PRESSURE GAUGE FOR MEASURING HYDRAULIC PRESSURES, ESPECIALLY FOR USE IN MINING HYDRAULICS |
| JPH0465643A (en) * | 1990-07-05 | 1992-03-02 | Mitsubishi Electric Corp | Semiconductor pressure sensor and its manufacture |
| FR2666411B1 (en) * | 1990-08-29 | 1995-07-07 | Souriau & Cie | METHOD AND APPARATUS FOR DETERMINING OPERATING CHARACTERISTICS OF AN EXPLOSION ENGINE WITH INDEPENDENT CYLINDER SUPPLY. |
| JPH06207870A (en) * | 1993-01-11 | 1994-07-26 | Mitsubishi Electric Corp | Semiconductor pressure sensor |
| US5868678A (en) * | 1993-06-30 | 1999-02-09 | Medex, Inc. | Two-part medical pressure transducer with diaphragm stand-offs |
| WO1997001364A1 (en) * | 1993-06-30 | 1997-01-16 | Medex, Inc. | Medical pressure transducer with sliding components |
| JPH08233848A (en) * | 1995-02-28 | 1996-09-13 | Mitsubishi Electric Corp | Semiconductor sensor |
| US5703296A (en) * | 1995-06-27 | 1997-12-30 | Delco Electronics Corp. | Pressure sensor having reduced hysteresis and enhanced electrical performance at low pressures |
| US5747694A (en) * | 1995-07-28 | 1998-05-05 | Nippondenso Co., Ltd. | Pressure sensor with barrier in a pressure chamber |
| US5763787A (en) * | 1996-09-05 | 1998-06-09 | Rosemont Inc. | Carrier assembly for fluid sensor |
| JP2004309212A (en) * | 2003-04-03 | 2004-11-04 | Denso Corp | Pressure sensor, and suction system pressure measuring apparatus |
| US7530826B2 (en) * | 2006-09-15 | 2009-05-12 | Honeywell International Inc. | Sealed cavity with vent hole method and apparatus for use in sensor modules |
| FR2942875A3 (en) * | 2009-03-03 | 2010-09-10 | Renault Sas | Sensor for measuring e.g. temperature, of gas circulating inside gas guiding tube of internal combustion heat engine of motor vehicle, has mechanical fixing unit formed of rib and groove to fix electric conductor on sensor |
| JP2019052571A (en) * | 2017-09-14 | 2019-04-04 | ホシデン株式会社 | Sensor and operation state monitoring system |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1785861A (en) * | 1927-10-26 | 1930-12-23 | Ralph L Skinner | Air-cooled internal-combustion engine |
| US1921162A (en) * | 1930-07-24 | 1933-08-08 | Nat Electric Prod Corp | Electrical wiring appliance |
| US3520191A (en) * | 1968-08-22 | 1970-07-14 | Kistler Instr Corp | Strain gage pressure transducer |
| JPS5112437B2 (en) * | 1971-10-01 | 1976-04-19 | ||
| NL7415668A (en) * | 1974-12-02 | 1976-06-04 | Philips Nv | PRESSURE TRANSMITTER. |
| CH592300A5 (en) * | 1975-07-08 | 1977-10-31 | Keller Hans W | |
| US4131088A (en) * | 1976-11-08 | 1978-12-26 | The Bendix Corporation | Multiple function pressure sensor |
| US4129042A (en) * | 1977-11-18 | 1978-12-12 | Signetics Corporation | Semiconductor transducer packaged assembly |
| JPS5492382A (en) * | 1977-12-29 | 1979-07-21 | Nissan Motor | Pressure detector |
| JPS54113379A (en) * | 1978-02-23 | 1979-09-04 | Nec Corp | Pressure gauge |
-
1979
- 1979-02-05 JP JP1144979A patent/JPS55103438A/en active Pending
-
1980
- 1980-01-31 US US06/117,078 patent/US4325260A/en not_active Expired - Lifetime
- 1980-02-04 DE DE8080100540T patent/DE3061837D1/en not_active Expired
- 1980-02-04 EP EP80100540A patent/EP0014452B1/en not_active Expired
- 1980-02-05 AU AU55229/80A patent/AU531193B2/en not_active Ceased
- 1980-02-05 CA CA000345064A patent/CA1152180A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| AU531193B2 (en) | 1983-08-11 |
| DE3061837D1 (en) | 1983-03-17 |
| AU5522980A (en) | 1980-08-14 |
| EP0014452A3 (en) | 1980-10-29 |
| US4325260A (en) | 1982-04-20 |
| EP0014452B1 (en) | 1983-02-09 |
| JPS55103438A (en) | 1980-08-07 |
| EP0014452A2 (en) | 1980-08-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |