JP2003329651A - Gas sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify the configuration of a sensor by simplifying the electric wiring of a detecting element and a circuit board in a gas sensor and to optimize the arrangement position of an element for measuring the temperature of gas. <P>SOLUTION: This gas sensor detects the property of gas in a detecting chamber 28 using a detecting element body 40 and a thermistor 60. The thermistor 60 is provided in a temperature measuring chamber 25 different from the detecting chamber 28 and located not to project from an inlet thereof. The detecting element body 40 has metal piece terminals 55a, 55b, and also the thermistor 60 has metal piece terminals 64a, 64b. These elements 40, 60 are respectively connected to an electronic circuit board 70 so that the terminals 55a, 55b, 64a, 64b are arranged side by side in the same direction. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas sensor for detecting a property of gas depending on a predetermined property and temperature of the gas.

[0002]

2. Description of the Related Art Conventionally, there has been known a gas sensor which detects a property of a gas existing in a flow path, for example, a concentration of a specific component, a temperature, a humidity or the like by using a detection element. In such a gas sensor, the signal from the detection element is electrically processed and output as an electric signal corresponding to the property of the gas. As an example of such a gas sensor, a gas concentration sensor that is provided in a transportation device such as an automobile equipped with an internal combustion engine and that detects the concentration of gasoline, light oil, or the like by utilizing the change in the propagation velocity of ultrasonic waves will be taken up. Such a gas concentration sensor is provided, for example, in the middle of a purge line connected from a canister mounted in an automobile to an intake pipe of an internal combustion engine, and a vaporized fuel containing gasoline or the like is included in a passage of a predetermined volume formed in the sensor. It is configured to allow gas to pass. When the concentration of gasoline vapor changes, the speed of the ultrasonic wave passing through the evaporated fuel gas changes, so this change is detected by the ultrasonic receiver, the signal is processed, and output as a signal corresponding to the gasoline concentration. To do. The following technologies are known as such gas sensors.

[Patent Document 1] Japanese Unexamined Patent Publication No. 2000-249691

FIG. 15 is a sectional view showing an example of the structure of a conventional gas concentration sensor 100. This gas concentration sensor 1
00 has a metal flow path forming member 110, and the flow path forming member 110 constitutes a measurement chamber 120 and a circuit board housing chamber 130. A piezoelectric element 140 is installed at the upper end of the measurement chamber 120, and a circuit board 150 is installed in the circuit board housing chamber 130. A temperature sensor 160 is externally inserted on the side surface of the measurement chamber 120 at the center thereof. The circuit board 150 is electrically connected to the piezoelectric element 140 and the temperature sensor 160. The concentration of the component (for example, gasoline) in the gas introduced into the measurement chamber 120 is determined according to the propagation time of ultrasonic waves in the measurement chamber 120 and the temperature of the gas.

In the conventional gas concentration sensor 100, the temperature sensor 160 is provided on the side surface of the measuring chamber 120 as in this example. The reason for this is that the propagation time of the ultrasonic wave depends not only on the concentration of the gas component but also on the temperature of the gas, so that the temperature of the gas should be measured accurately.

[0005]

However, in the conventional gas concentration sensor 100, there is a problem that the wiring between the temperature sensor 160 and the circuit board 150 becomes long and the routing thereof becomes complicated. There is also a problem that a protective material is required to prevent the wiring from being cut. In addition, the temperature sensor 160 is
Because it is fixed from the outside on the side of 0,
There may be a problem with the airtightness of the measurement chamber 120.

Further, depending on the method of detecting the characteristics of the gas, it may not be desirable to provide the temperature sensor in the measuring chamber. For example, in the gas concentration sensor 100 of the type shown in FIG. 15, since the measurement is performed using the ultrasonic wave transmitted from the piezoelectric element 140, the measurement chamber 120 in which the ultrasonic wave propagates has a spatial symmetry. There has been a demand to avoid placing members that cause disturbance. However, if the temperature sensor 160 is provided outside the measurement chamber 120, for example, in the passage 170 through which gas flows into the measurement chamber 120,
Before the temperature of the gas in the measurement chamber 120 changes, the passage 1
Since the temperature change of the gas inside 70 is detected, there is a problem that the temperature of the gas inside the measurement chamber 120 cannot be accurately detected.

The above-mentioned problem is not limited to the gas concentration sensor, but is also applicable to a gas sensor using a characteristic detecting element for detecting a predetermined characteristic of gas and a temperature detecting element for detecting the temperature of the gas. It was a common problem.

The present invention has been made to solve the above-mentioned conventional problems, and simplifies the structure of the sensor by simplifying the electrical wiring between the detection element of the gas sensor and the circuit board. The purpose is to provide the technology that can do. Another object of the present invention is to provide a technique capable of accurately detecting the temperature of gas in the characteristic measuring chamber even when the temperature detecting element is provided outside the characteristic measuring chamber in which the characteristic detecting element is arranged.

[0009]

[Means for Solving the Problems and Their Actions and Effects] In order to solve at least a part of the above problems, the first aspect of the present invention
The gas sensor is a gas sensor for detecting a property of the gas according to a predetermined property and temperature of the gas, and a characteristic detection element for detecting the predetermined property of the gas, and an electrical connection to the characteristic detection element. A characteristic detecting element assembly having a first metal piece terminal connected to the temperature detecting element, a temperature detecting element detecting the temperature of the gas, and a second metal piece terminal electrically connected to the temperature detecting element. And a circuit board electrically connected to the characteristic detection element and the temperature detection element via the first and second metal piece terminals, respectively. Further, the characteristic detecting element assembly and the temperature detecting element assembly are respectively connected to the circuit board in a state where the first and second metal piece terminals are arranged in parallel along the same direction. The point is that it is installed.

In this gas sensor, the first characteristic detecting element is used.
And the second metal piece terminal of the temperature detecting element are respectively connected to the circuit board in a state where they are arranged in parallel along the same direction. Therefore, these two detecting element and the circuit are connected. The electrical wiring with the substrate is simplified, and the configuration of the sensor can be simplified.

The gas sensor further includes a characteristic measuring chamber for detecting a predetermined characteristic of the gas by using the characteristic detecting element, and a temperature measuring device for detecting the temperature of the gas by using the temperature detecting element. A temperature measuring chamber may be provided at a position different from the characteristic measuring chamber in the middle of the gas flow path in the gas sensor.

According to this structure, since the temperature measuring chamber is provided at a position separate from the characteristic measuring chamber, the measuring error of the characteristic detecting element which may be caused by adjoining the temperature measuring chamber to the characteristic measuring chamber is reduced. can do. As a result, it is possible to improve the accuracy of the measurement itself of the property of gas.

The gas sensor further includes a circuit board housing chamber for housing the circuit board, the circuit board housing chamber, the characteristic measuring chamber, the temperature measuring chamber, and the gas flow path. Is a flow path forming member integrally formed of resin so that the circuit board storage chamber and the characteristic measurement chamber and the circuit board storage chamber and the temperature measurement chamber communicate with each other. The characteristic detection element assembly is fixed in a state of sealing between the circuit board storage chamber and the characteristic measurement chamber, and the temperature detection element assembly is connected to the circuit board storage chamber. The temperature measuring chamber may be fixed in a sealed state.

According to this structure, since the characteristic detecting element assembly and the temperature detecting element assembly are arranged in the space formed by the flow path forming member, some problems may occur in the sealed state. Even if it does, it is possible to prevent the gas from leaking to the outside immediately.

The temperature measuring chamber is formed as a concave portion provided in the gas sensor so as to face the gas flow passage, and the temperature detecting element is connected to the temperature detecting element through an inlet of the concave portion facing the flow passage. The ratio of the distance to the tip to the inner diameter of the recess may be set in the range of 0 to 2.0.

The value of the ratio of the distance from the inlet of the recess facing the flow path to the tip of the temperature detecting element and the inner diameter of the recess is determined by the temperature of the gas measured in the temperature measuring chamber and the temperature in the characteristic measuring chamber. It was found that there was an effect on the difference between the temperature of the gas and. Further, it has been found that when the value of this ratio is set in the range of 0 to 2.0, this temperature difference is small and the measurement accuracy of the properties of the gas is improved.

The gas sensor further includes a bypass flow passage that bypasses the characteristic measurement chamber so that a larger amount of gas can pass through than the characteristic measurement chamber, and the temperature measurement chamber has a surface on the bypass flow passage. It may be provided at a different position.

According to this structure, since the temperature measuring chamber is provided at the position facing the bypass passage, the temperature of the gas can be measured more accurately.

The characteristic detecting element is an element for detecting the propagation velocity of the ultrasonic wave of the gas, and the gas sensor is included in the gas according to the propagation velocity of the ultrasonic wave and the temperature of the gas. It may be a sensor that detects the concentration of at least one type of gas component.

According to this gas sensor, it is possible to accurately measure the concentration of the gas component.

The second gas sensor of the present invention is a gas sensor for detecting the property of the gas according to a predetermined property and temperature of the gas, and the property measurement of the inflow of the gas for detecting the property. Of the gas in a temperature measuring chamber provided facing the chamber and detecting a predetermined characteristic of the gas in the characteristic measuring chamber, and a temperature measuring chamber provided facing the flow path of the gas flowing into the characteristic measuring chamber. A temperature detecting element for detecting a temperature; and a circuit for processing the output of the characteristic detecting element using the output of the temperature detecting element and calculating at least a parameter relating to the property of the gas, the temperature detecting element The gist of the present invention is to dispose the tip at a position where it does not project with respect to the inlet of the temperature measuring chamber.

In such a gas sensor, even if the temperature detecting element is provided in the temperature measuring chamber separated from the characteristic measuring chamber in which the characteristic detecting element for detecting the characteristic of the gas is arranged, the gas flowing into the characteristic measuring chamber is Since the temperature measuring chamber flows through the facing channel, the temperature of the gas in the characteristic measuring chamber can be detected with high accuracy.

In this case, the position of the temperature detecting element is set such that the ratio of the distance from the inlet of the temperature measuring chamber to the tip of the temperature measuring chamber and the inner diameter of the temperature measuring chamber is in the range of 0 to 2.0. Can be set. By adopting such a relationship, the measurement error can be sufficiently suppressed.

Further, the temperature measuring chamber can be provided substantially at right angles to the flow direction of the gas in the flow path. Further, it is also desirable to set the outer diameter of the temperature detecting element to 1/2 or less of the inner diameter of the temperature measuring chamber from the viewpoint of gas replacement in the temperature measuring chamber.

The present invention can be realized in various modes, for example, a gas sensor, a method of manufacturing a gas sensor, a method of detecting or measuring a characteristic or property of gas, and the like. it can.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below based on Examples. FIG. 1 is an exploded perspective view of a gas sensor as a first embodiment of the present invention. The gas sensor 10 is a sensor that detects the concentration of gasoline vapor by utilizing the fact that the propagation velocity of ultrasonic waves changes depending on the gas concentration. This gas sensor is arranged, for example, in a passage for purging gasoline from an canister mounted on a vehicle powered by an internal combustion engine to an intake passage, and is used for the purpose of detecting the concentration of purged gasoline.

(A) Overall Structure of Gas Sensor: As shown in FIG. 1, the gas sensor 10 is roughly composed of a flow path forming member 20 which forms a flow path through which a gas whose concentration is to be detected passes. The detection element body 40 housed in the housing 22 integrally formed in the flow path forming member 20, the thermistor 60 for detecting the temperature of the gas passing through the flow path, and the detection element body 40 are arranged above the detection element body 40. It is composed of an electronic circuit board 70 and a metal case 80 fitted in the housing portion 22. The detection element body 40 is fixed by ultrasonic welding to the mounting recess 24 provided in the housing 22, and the thermistor 60 is inserted and fixed in the mounting thermistor insertion hole 25. As will be described later, the detection element body 40 and the thermistor 60 have terminals for exchanging electrical signals, and these terminals are inserted into corresponding mounting holes of the electronic circuit board 70 and fixed by soldering. To be done. The gas sensor 10 has the detection element body 40 and the thermistor 60 fixed to the housing portion 22,
The electronic circuit board 70, which is a board for signal processing, is attached, the case 80 is further fitted into the housing portion 22, and the whole is molded with a resin such as urethane. The manufacturing process of the gas sensor 10 will be described in detail in (F).

(B) Structure of the flow path forming member 20: The flow path forming member 20 of the gas sensor 10 is formed by molding a synthetic resin containing glass filler, and its elastic modulus is adjusted to an appropriate value for the gas sensor. ing. This flow path forming member 20, as shown in FIG.
A storage portion 22 for storing 0 is provided, and a flow path through which a gas for detection flows is provided below the storage portion 22. As a main flow path, an introduction path 27 for introducing a gas containing gasoline vapor into the gas sensor 10, a measurement chamber 28 for ultrasonically detecting the gasoline concentration in this gas, and a gas bypassing the measurement chamber 28. A bypass channel 29 is formed. The measurement chamber 28 is provided substantially directly below the detection element body 40, and the bypass flow path 29 is provided substantially directly below the thermistor 60.

To explain such a flow channel structure in detail, a vertical cross section of the gas sensor 10 is shown in FIG. Figure 2
The gas sensor 10 is connected to the introduction path 27 and the detection element body 4
It is sectional drawing cut | disconnected by the plane containing the 0 axis line. Although the gas sensor 10 is finally filled with resin (for example, urethane) and molded, in FIG. 2, the resin for molding the whole is not drawn for the sake of simplicity of illustration. Figure 2
As shown in FIG. 4, the inside of the flow path forming member 20 is focused on the flow path, the introduction path 27, the measurement chamber 28, and the bypass flow path 29.
It is divided into These can be easily molded by movably providing a mold for molding. Introductory route 2
7 communicates with the bypass flow path 29 at a right angle, and also communicates with the measurement chamber 28 via the introduction hole 32. An outlet 34 is formed below the bypass passage 29, and the introduction passage 2
Gas including gasoline vapor introduced from the
And is connected to the intake passage of the internal combustion engine by a hose (not shown). An end portion of the bypass flow passage 29 opposite to the outlet 34 is formed as an insertion hole 25 to which the thermistor 60 is attached. Therefore, the thermistor 60 has a predetermined relationship with the temperature of the gas flowing from the introduction passage 27 and detects it.

The measurement chamber 28 has a detection element body 40 at the top.
Is communicated with a concave portion 24 (FIG. 1) to which is attached, and a reflection portion 33 for reflecting ultrasonic waves is formed below the concave portion 24. Although the function of the reflecting portion 33 will be described later, it is structured such that it is lifted by a predetermined distance (several millimeters in this embodiment) from the bottom of the measuring chamber 28, and the void around the reflecting portion 33 is As it is, it is connected to the bypass flow passage 29 via the discharge flow passage 35 that communicates with the bottom of the measurement chamber 28. Therefore, the gas flowing from the introduction passage 27 through the introduction hole 32 fills the inside of the measurement chamber 28 and exits from the discharge passage 35 to the bypass passage 29 at a predetermined ratio. Since the discharge flow path 35 is provided at the bottom of the measurement chamber 28, when water vapor or gasoline vapor in the measurement chamber 28 is condensed and liquefied, it serves as a drain for discharging these water and oil droplets. Also works. The peripheral outer shape of the reflecting portion 33 is inclined toward the discharge flow path 35 so that the liquid accumulated in the groove around the reflecting portion 33 can be easily discharged.

As described above, the accommodating portion 22 formed on the flow path forming member 20 is provided with the mounting recess 24 having the opening communicating with the measuring chamber 28, the thermistor mounting insertion hole 25, and the like. This storage part 2
A metal plate 36 is insert-molded at a position corresponding to 2. The metal plate 36 has a cut-and-raised portion 83 at one corner thereof. After the insert-molding, the cut-and-raised portion 83 is erected inside the housing portion 22 as shown in FIG. 1, and is inserted into the mounting hole 72 on the board when the electronic circuit board 70 is mounted. To be done. In the mounting hole 72, a land connected to the ground line is prepared,
The cut-and-raised portion 83 is soldered to this land.
Note that the inner size of the mounting hole on the electronic circuit board 70 side is made smaller than the cut-and-raised portion 83, and the cut-and-raised portion 83 is press-fitted into the mounting hole 72 having a conductive material plated inside, so that the mechanical electrical It is also possible to realize physical contact. Of course, it is also possible to adopt methods such as press contact, fitting, and engagement.

A connector 31 for exchanging electrical signals is formed on the outside of the storage portion 22, and a terminal (not shown) forming the connector 31 penetrates the outer wall of the storage portion 22 at this portion. ing.

As can be understood from FIG. 2, at the time of molding the flow path forming member 20, the circuit board housing chamber 23 for housing the electronic circuit board 70 and the measuring chamber 28 (also called "characteristic measuring chamber") communicate with each other. The flow path forming member 20 is integrally molded with resin so that the circuit board housing chamber 23 and the thermistor insertion hole 25 (also referred to as “temperature measuring chamber”) communicate with each other.
However, in the state after assembly, the space between the circuit board housing chamber 23 and the measurement chamber 28 is sealed by the detection element body 40, and the circuit board housing chamber 23 and the thermistor insertion hole 25 are provided.
The space between and is also sealed by the thermistor 60.

As will be described later, the detection element body 4
0 includes an element for detecting the speed of sound of ultrasonic waves and another member (for example, a terminal for electrical connection), and thus is also referred to as a “sound speed detecting element assembly (sound speed detecting element assembly)”. Further, for the same reason, the thermistor 60 is also called a "thermistor assembly (thermistor assembly)". In addition,
A sensor such as a thermocouple other than the thermistor can be used as the temperature sensor.

(C) Structure of the detecting element body 40 and the thermistor 60: The structure of the detecting element body 40 is shown in the sectional view of FIG. As shown in FIG. 1, the detection element body 40 has a disk shape after assembly, but this is inside a synthetic resin element case 42 having a flange portion 41.
This is because urethane is filled inside after accommodating a piezoelectric element described later. The flange portion 41 of the element case 42 has a mounting recess 24 provided in the storage portion 22.
(See FIG. 1) The diameter is larger than that of the flange portion 41, and the accommodating portion 43 below the flange portion 41 is smaller than the recess 24. In the state of the element case 42 alone, the lower surface of the housing portion 43 is opened, and the outer edge of the end surface 45 thereof is
A step portion 46 is formed. At the time of manufacturing, a circular protective film 48 made of a gasoline resistant material is adhered to the inside of the step portion 46.

A cylindrical acoustic matching plate 50 is bonded and fixed to the center of the protective film 48, and a piezoelectric element 51 for transmitting and receiving ultrasonic waves by utilizing the piezoelectric effect is provided on the upper surface of the acoustic matching plate 50. Is glued and fixed. The acoustic matching plate 50 efficiently transmits the vibration of the piezoelectric element 51 to the air (in the present embodiment, the measuring chamber 28 through the protective film 48).
It is provided for sending. Sound waves and ultrasonic waves
Since it is easy to be reflected in a place where there is a difference in the density of the medium, the piezoelectric element 51 is not directly adhered to the protective film 48, but is joined via the acoustic matching plate 50 to efficiently vibrate the piezoelectric element 51. The ultrasonic waves can be transmitted into the measurement chamber 28. In this embodiment, the acoustic matching plate 50
As the material, a large number of small glass beads hardened with an epoxy resin were used. Further, a cylindrical body 52 is arranged so as to surround the acoustic matching plate 50 and the piezoelectric element 51. The tubular body 52 is obtained by laminating a copper foil 52c on a polyethylene terephthalate film 52a via an adhesive layer 52b, and winding it in a cylindrical shape with the side of the copper foil 52c inside and laminating the end faces. is there. Since the inner diameter of the tubular body 52 is substantially the same as the outer diameter of the acoustic matching plate 50, the tubular body 52 is in close contact with the outer periphery of the acoustic matching plate 50. The two are not glued.

The piezoelectric element 51 is formed by forming an electrostrictive element such as a piezo into a columnar shape. When a voltage is applied to the electrodes formed on the upper and lower surfaces in the axial direction, distortion occurs only in the axial direction. It is cut out by adjusting the direction of the lattice. As will be described later, the piezoelectric element 51 functions as a transmitter that sends ultrasonic waves into the measurement chamber 28, but at the same time, it also functions as a receiver that receives ultrasonic vibrations and outputs electric signals. Of course, it is also possible to make a gas sensor by separately providing a transmitting element and a receiving element. As the piezoelectric element 51, piezoelectric ceramics, a crystal body such as quartz, or the like can be appropriately used. Although not particularly shown, the electrodes may be formed on the upper and lower surfaces of the piezoelectric element 51 by a method such as vapor deposition, or may be configured by attaching a thin metal plate.

The element case 42 has a substantially inverted "L" -shaped cross section, and its inner peripheral surface is tapered at a predetermined angle (about 11 degrees in this embodiment) with respect to the vertical plane. It is attached. Therefore, the portion corresponding to the outer wall of the housing portion 43 is
The thickness increases toward the lower portion, that is, the protective film 48. As a result, the accommodating portion 43 of the element case 42 has a thin outer wall near the base of the flange portion 41 and is highly flexible, and at its lower end, a sufficient area for attaching the protective film 48 is prepared. There is. Although the element case 42 is formed in a substantially cylindrical shape, it has a shape that protrudes inward only at the portions where the terminals 55a and 55b are embedded. The terminals 55 embedded in the protrusions 56a and 56b
The a and 55b are bent in an "L" shape, and the lead wires 54a and 54b are soldered to the lower ends thereof. The upper ends of the terminals 55a and 55b are inserted into the corresponding mounting holes of the electronic circuit board 70, and are soldered to the lands prepared at the positions. Thus, the lead wire 5 of the piezoelectric element 51
After the mounting of 4a and 54b is completed, the inside of the element case 42 is filled with urethane.

The element case 42 is provided with a protrusion 59 for welding in a circumferential shape substantially at the center of the lower surface of the flange portion 41. The protrusion 59 is melted during ultrasonic welding, and the flange portion 4
1 is firmly fixed to the mounting recess 24 of the storage portion 22.

FIG. 4 is a sectional view showing the structure of the thermistor 60. This thermistor 60 has a cylindrical first holder 62 holding a heat-sensitive portion 61 having a thermistor element.
However, it has a configuration in which it is inserted into a concave portion on the lower side of the slightly larger second holder 63 and fixed with an adhesive. Above the second holder 63, the two terminals 64a, 6 of the metal piece are provided.
4b is fixed and protrudes. The two lead wires 65a and 65b of the heat-sensitive portion 61 are taken out above the holder 63 through a through hole formed in the center of the second holder 63 and connected to the two terminals 64a and 64b, respectively. . In addition, two lead wires 65 are provided in the through hole in the center.
Insulating sheaths 66a, 6b are attached to the lead wires 65a, 65b to prevent the a, 65b from electrically contacting each other.
6b is attached. This insulating sheath 66a, 6
As 6b, for example, a polyimide tube can be used. The thermistor 60 thus assembled is fixed in the thermistor insertion hole 25 (FIG. 1). This fixing can be performed by various methods such as an adhesive or ultrasonic welding.

As shown in FIG. 2, the detection element body 40 and the thermistor 60 are provided with a metal piece terminal 55 thereof.
The a, 55b, 64a and 64b are connected to the electronic circuit board 70 in a state of being arranged in parallel in the same direction.
Therefore, in particular, the electrical connection structure between the thermistor 60 and the circuit board 70 is greatly simplified as compared with the conventional structure. Also, at the time of assembly, each terminal 55a, 55b, 64a,
This connecting step is also simplified because the 64b may be passed through a through hole provided in the electronic circuit board 70 in advance and soldered to a land provided on the upper side of the electronic circuit board 70. As described above, according to the configuration of the gas sensor of the present embodiment, it is possible to assemble the detection element body 40 and the thermistor 60 at the same time, and as a result, the reliability at the time of assembly can be improved and the cost can be reduced. . Further, since the terminals 55a, 55b, 64a, 64b do not pass through the outside of the flow path forming member 20 but only through the inside thereof, the terminals 55a are filled with the filler (resin mold) filled in the circuit board housing chamber 23. , 55b, 64a, 64
b is also protected. Therefore, there is also an advantage that it is not necessary to provide a special protective material for these terminals.

As described above, the flow path forming member 20.
At the time of molding, the thermistor insertion hole 25 (temperature measurement chamber) to which the thermistor 60 is attached, and the circuit board storage chamber 23
And are integrally formed as a communicating space. Therefore, even if the airtightness of the mounting portion of the thermistor assembly 60 is lowered to some extent, the gas in the temperature measuring chamber 25 is not likely to directly leak to the outside and only spreads to the circuit board housing chamber 23 side. . This circuit board storage room 23
Since it is resin-molded, there is no risk of gas leaking out. Therefore, the gas sensor of the present embodiment has an advantage that the gas sensor is highly reliable in preventing leakage of gas to the outside, as compared with the conventional gas sensor shown in FIG.

(D) Electronic circuit board 70 and its circuit and method for detecting gas concentration: Next, the structure of the electronic circuit board 70 and its mounting will be described. The electronic circuit board 70 is
A circuit pattern is formed in advance on a glass epoxy substrate by etching or the like, and lands and through holes are provided at component mounting positions. Further, a mounting hole having a size corresponding to the shape of each terminal is provided in a portion where the detecting element body 40, the thermistor 60, or the terminal of the connector 31 is mounted, and a land pattern surrounds the mounting hole. Therefore, the completed electronic circuit board 7
0 has various parts for signal processing, such as an integrated circuit (IC) for signal processing, resistors, capacitors, etc., attached at predetermined positions.
The electrical circuit configuration is completed by mounting the or thermistor 60 in the housing 22 where the mounting is completed and soldering. The gas sensor 10 is finally manufactured by resin molding, which will be collectively described later in the section of the manufacturing method.

The electrical structure of the gas sensor 10 thus completed is shown in the block diagram of FIG. As shown,
The electronic circuit board 70 is mainly composed of a microprocessor 91. Each circuit element connected to the microprocessor 91, that is, a timer 90, a digital-analog converter (D / A converter) 92, a driver 9 is provided.
3. A comparator 97 to which an amplifier 96 is connected is provided. The thermistor 60 is directly connected to the analog input port PAP of the microprocessor 91. Further, the driver 93 and the amplifier 96 are connected to the detection element body 40.

The timer 90 is for precisely measuring the time, and in the concentration detection of gasoline described later,
The ultrasonic wave transmitted from the detection element body 40 is used to accurately measure the time taken for the ultrasonic wave to be reflected by the reflecting portion 33 and returned in the measurement chamber 28 in which gasoline vapor exists. The driver 93 is a circuit that receives a command from the microprocessor 91 and drives the piezoelectric element 51 of the detection element body 40 for a short time (about 20 microseconds in the embodiment). When the rectangular wave signal output from the driver 93 is received, the piezoelectric element 51 vibrates and functions as a transmitter to send an ultrasonic wave into the measurement chamber 28.

The ultrasonic wave sent into the measuring chamber 28 goes straight while maintaining a relatively high directivity, and is reflected by the reflecting portion 33 at the bottom of the measuring chamber 28 and returns. When the returned ultrasonic waves reach the protective film 48, the vibration is transmitted to the piezoelectric element 51 through the protective film 48 and the acoustic matching plate 50, and the piezoelectric element 51 functions as a receiver this time and responds to the vibration. Output electrical signal. This state is shown in FIG. In the figure, a section P1 is a period during which the driver 93 is outputting a signal and the piezoelectric element 51 functions as a transmitter, and a section P2 is a vibration of the piezoelectric element 51 due to the ultrasonic waves reflected by the reflecting section 33. Each of the periods during which the piezoelectric element 51 is transmitted and functions as a receiver is shown.

The signal of the piezoelectric element 51 when functioning as a receiver is input to the amplifier 96 and amplified. In the embodiment, the amplifier 96 uses a differential amplifier that is resistant to noise. The output of the amplifier 96 is input to the comparator 97, where it is compared with a threshold value Vref prepared in advance. The threshold value Vref is set to the amplifier 9 due to the influence of noise or the like.
This is a level at which an erroneous signal output by 6 can be discriminated. The erroneous signal includes not only noise, but also reverberation of the detection element body 40 itself.

The comparator 97 compares the signal from the amplifier 96 with the threshold value Vref to invert the output when the magnitude of vibration received by the piezoelectric element 51 exceeds a predetermined level. The output of the comparator 97 is monitored by the microprocessor 91, and from the output timing of the first ultrasonic wave from the piezoelectric element 51 (timing t1 in FIG. 6) until the output of the comparator 97 is inverted (timing t2 in FIG. 6). By measuring the time Δt, it is possible to know the time required for the ultrasonic wave to travel back and forth the distance L to the reflecting portion 33 in the measurement chamber 28. It is known that the velocity C of ultrasonic waves propagating in a certain medium follows the following equation (1).

[0049]

[Equation 1]

This equation (1) is a general equation that holds for a gas in which a plurality of components are mixed, and the variable n is the nth
It is a suffix indicating that it is for a component. Therefore, Cpn is the constant pressure specific heat of the nth component of the gas existing in the measurement chamber 28, Cvn is the constant volume specific heat of the nth component of the gas in the measurement chamber 28, Mn is the molecular weight of the nth component, and Xn is the nth component. It represents the concentration ratio. Further, R is a gas constant, T is a measurement chamber 2
The temperature of the gas in 8. Since the specific heat of the gas is known, the propagation velocity C is determined only by the temperature T of the gas in the measurement chamber 28 and the concentration ratio Xn. The propagation velocity C of the ultrasonic wave can be expressed as C = 2 × L / Δt (2) using the distance L from the piezoelectric element 51 to the reflecting portion 33. Therefore, if Δt is measured, the concentration ratio Xn, that is,
The gasoline concentration can be calculated. Although the concentration of gasoline vapor is detected in the present embodiment, if the concentration is known, it can be used as a sensor for obtaining the temperature T and the distance L.

The microprocessor 91 performs the calculation according to the above equation at high speed and outputs a signal corresponding to the obtained gasoline concentration via the D / A converter 92. This signal SGNL is output to the outside via the terminal of the connector 31. In the embodiment, this signal SGNL is output to a computer that controls the fuel injection amount of the internal combustion engine, where the amount of gasoline purged from the canister is taken into consideration.
It is used for processing such as correcting the fuel injection amount. Although lines related to the power supply are not shown in FIG. 5, the elements such as the microprocessor 91 are not shown.
In both cases, a power supply line for supplying a DC voltage Vcc and a ground (ground line) are connected. Of these, the ground line is connected to the metal plate 36 insert-molded at the position of the housing portion 22 of the flow path forming member 20 and the case 80, as already described. Although these members are schematically illustrated in FIG. 5, the metal plate 36 (see FIG. 2) and the case 8 are illustrated.
0 (see FIG. 1) is combined with each other to form a box that covers the detection element body 40 (see FIG. 2), and since it is kept at the same potential, it is electrically electromagnetic shielded. Has been realized. Therefore, the detection element body 40 and the electronic circuit board 70 housed inside are effectively protected against noise from the outside.

(E) Relationship between the structure of the thermistor 60 and the measurement accuracy: FIG. 7 shows the thermistor 60 and the thermistor insertion hole 2.
5 is an enlarged sectional view showing the periphery of FIG. In addition, below, the thermistor insertion hole 25 is referred to as a “temperature measurement chamber 25”. Part of the gas passing through the gas introduction path 27 is guided into the measurement chamber 28, and the other part flows through the bypass flow path 29. Measuring room 28
The amount of gas introduced into the bypass passage 29 is smaller than the amount of gas flowing in the bypass passage 29, and most of the gas flows in the bypass passage 29. The reason for this is that if a turbulent flow occurs in the measurement chamber 28, the measurement error will increase, so that the flow in the measurement chamber 28 will be kept as close to the laminar flow as possible.

The temperature measuring chamber 25 is provided in the flow path upstream of the measuring chamber 28. Particularly, in this embodiment, the temperature measuring chamber 25 is provided at a position facing the bypass flow path 29. Since a large amount of gas is flowing at this position, there is an advantage that the gas temperature can be measured more accurately.

As can be understood from the above equations (1) and (2), the measurement of the gas concentration depends on the gas temperature T. The gas temperature T is originally the temperature of the gas in the measurement chamber 28. However, as described in the related art, when the thermistor is installed in the measurement chamber 28, there is a problem that the structure for electrical connection of the thermistor becomes complicated. Further, by installing the thermistor, dust, water, and the like are likely to accumulate in the measurement chamber 28, which may adversely affect the measurement accuracy. Therefore, in this embodiment,
These problems are avoided by installing the thermistor 60 in a space different from the measurement chamber 28.

If the thermistor 60 is arranged in a space different from the measuring chamber 28, the accuracy of measuring the gas temperature T becomes a problem. For example, when a high temperature gas suddenly flows into the introduction path 27, the gas in the temperature measurement chamber 25 immediately becomes high temperature, but the gas in the measurement chamber 28 remains low temperature. The opposite case is also possible. In these cases, the temperature of the gas that is the object of sound velocity detection and the temperature of the gas that is the object of temperature measurement (thermistor indicated value)
And will not match. The error in the temperature measurement results in an error in the concentration measurement as shown in FIG.

The inventors of the present invention have found that such a problem relating to temperature measurement can be solved by appropriately setting the relationship between the size of the thermistor 60 and the size of the temperature measuring chamber 25. As described above, the heat sensitive portion 61 including the thermistor element is embedded in the holder 62. The smaller the outer diameter φd of the holder 62 (that is, the smaller the heat capacity of the holder 62) is, the less heat is transferred between the heat-sensitive portion 61 and the holder 62. Therefore, the measurement error due to the temperature fluctuation in the heat-sensitive portion 61 is reduced. There is a tendency. Further, as the length c of the first holder 62 exposed from the second holder 63 is longer, the heat transfer between the heat-sensitive portion 61 and these holders 62, 63 is reduced, so that the temperature in the heat-sensitive portion 61 is reduced. Measurement errors due to fluctuations tend to decrease. In other words, the accuracy of temperature measurement can be improved by making the outer diameter φd of the holder 62 as small as possible and making its length c as long as possible.

It was also found that the relationship between the distance b from the inlet of the temperature measuring chamber 25 to the heat-sensitive portion 61 and the inner diameter φa of the temperature measuring chamber 25 has a great influence on the error in temperature measurement.
FIG. 9 is a graph showing the effect of the ratio b / φa of these dimensions on the error in temperature measurement. When the value of the ratio b / φa is excessively small, the temperature instruction value by the thermistor 60 becomes higher than the gas temperature in the measurement chamber 28 when a high temperature gas suddenly flows. As a result, due to the characteristics of FIG. 8, the measured density value is higher than the actual density. On the other hand, when the value of the ratio b / φa is excessively large, when the high temperature gas suddenly flows, the thermistor 6
The temperature indication value of 0 is smaller than the gas temperature in the measurement chamber 28. As a result, due to the characteristics of FIG. 8, the measured density value becomes lower than the actual density. It should be noted that when the low-temperature gas suddenly flows, the tendency is opposite to the above.

Thus, it was found that the temperature measurement error and the resulting concentration measurement error depended on this ratio b / φa. FIG. 10 is an explanatory diagram showing the influence on the concentration measurement error when there is a change in the gas temperature, and FIG. 10 (A) shows the measurement error for this ratio b / φa ratio, and FIG.
Is a graph in which an error is plotted with respect to this ratio b / φa. As shown in the figure, the experimental results are obtained when the gas at about 80 ° C. is suddenly flown from the room temperature. As shown in this graph, by setting the value of the ratio b / φa in the range of more than 0 and 2.0 or less, it is possible to suppress the influence of the temperature change of the gas on the concentration measurement error. Is. If the ratio b / φa is larger than 0, it means that at least the heat sensitive portion 61 at the tip of the thermistor 60 is in the temperature measuring chamber 25.
It means that it does not protrude from the entrance of. Further, if the diameter φd of the thermistor 60 is 1/2 or less of the inner diameter φa of the temperature measuring chamber 25, the gas in the temperature measuring chamber 25 can be smoothly replaced, and a temperature error due to the retention of the gas also occurs. Hateful.

(F) Method for manufacturing gas sensor: Next, regarding the method for manufacturing the gas sensor 10 in the present embodiment,
explain. FIG. 11 is a process chart showing the manufacturing process of the gas sensor. As shown in the figure, when manufacturing the gas sensor 10, first, a piezoelectric element is assembled (step S1).
00). On the other hand, an element case 42 (FIG. 3) enclosing the thus obtained piezoelectric element assembly is prepared (step S11).
0). The element case 42 is manufactured by pouring a synthetic resin containing a glass filler into a mold, but a method such as shaving may be used.

Next, the work of assembling the detection element body 40 is performed (step S120). In this step, first, in step S100, the element case 42 manufactured in step S110 is formed.
Assemble the piezoelectric element assembly assembled in. In this state,
The cylindrical body 52 is inserted from the opening side of the element case 42 and fitted into the outer periphery of the acoustic matching plate 50 (step S13).
0). Prior to the work, the copper foil 52c bonded to the polyethylene terephthalate film 52a via the adhesive layer 52b is wound in advance on the inner diameter matched with the outer diameter of the acoustic matching plate 50 to manufacture the tubular body 52. Cylinder 52
Is not particularly adhered, but is simply fitted to the acoustic matching plate 50.

In this state, the work of connecting the two lead wires 54a and 54b extending from the piezoelectric element 51 to the terminals 55a and 55b by soldering or the like is performed (step S1).
40). Through the above processing, all the necessary parts are assembled to the detection element body 40. Therefore, next, a process of filling urethane from the opening side of the element case 42 is performed (step S150). Note that urethane is omitted in FIGS. 2 and 3.

The flow path forming member 20 (FIG. 2) is manufactured separately from the manufacturing of the detection element body 40 described above. This step is shown below step S200. When the flow path forming member 20 is manufactured, first, a metal plate is pressed to form a metal plate 36 for insert molding (step S200).

Next, the flow path forming member 20 is insert-molded so that the metal plate 36 is provided therein (step S210). The flow path forming member 20 is molded using a synthetic resin containing glass filler.

After the flow path forming member 20 is manufactured in this way,
The recess 24 at the bottom of the housing 22 of the flow path forming member 20
Then, the operation of welding the already-manufactured detection element body 40 is performed (step S230). The welding is performed by ultrasonic welding. After mounting the detection element body 40 on a predetermined jig, the detection element body 40 is attached to the center of the recess 24.
The centers of the jigs are made to coincide with each other, and the jig is vibrated at a frequency in the ultrasonic range to strongly hit the lower surface of the flange portion 41 (FIG. 3) to the joint surface of the housing portion 22. As shown in FIG.
Since the projection 59 is formed on the lower surface of the flange portion 41, all the force due to the ultrasonic vibration is concentrated on the projection 59, and the projection 59 is heated by the concentration of mechanical energy, and eventually the projection 59 is heated. To melt. As a result, the detection element body 40 is welded on the lower surface of the flange portion 41 to the joint surface of the housing portion 22 of the flow path forming member 20 without any gap. The state before and after the attachment of the detection element body 40 is shown in FIG.
The results are shown in (A) and (B). It should be noted that the welding includes hot plate welding,
It may be based on another method.

Before or after the detection element body 40 is attached, the operation of attaching the thermistor 60 to the thermistor insertion hole 25 of the flow path forming member 20 is also performed (step S240).
After that, the cushioning material 88 is placed on the detection element body 40 (step S250). The cushioning material 88 is the detection element body 4
It is a foam having an outer diameter substantially the same as that of 0, and its thickness is several millimeters. The buffer material 88 is also provided with an opening through which the terminals 55a and 55b protruding upward from the detection element body 40 pass. The cushioning material 88 is used for the electronic circuit board 70 and the detection element body 40 to be attached in the subsequent steps.
The urethane foam having a thickness that can be interposed between and is used for the purpose of not filling the periphery of the detection element body 40 with the urethane foam filled in the step described later.

After arranging the cushioning material 88, as shown in FIG. 13A, the electronic circuit board 70 is mounted while fitting the following four members into the mounting holes prepared on the electronic circuit board 70. , From above, in the storage unit 22 (step S2
60). That is, a cut-and-raised portion 83 that is cut and raised from the metal plate 36 and stands upright on the bottom of the storage portion 22,
b, the terminals 64a and 64b of the thermistor 60, the four terminals of the connector 31, and the four members are fitted into predetermined mounting holes of the electronic circuit board 70. Of these, the terminals for GND, SGNL, and Vcc shown in FIG. 5 among the plurality of terminals of the connector 31 are soldered to lands provided around the mounting holes on the electronic circuit board 70.

Next, as shown in FIG. 13B, the work of attaching the case 80 to the storage portion 22 is performed (step S270). At this time, one terminal 31d of the plurality of terminals of the connector 31 is passed through the insertion hole 85 provided in the case 80, and then this is soldered or brazed. This completes the mounting work of the case 80. After that, the work of filling the resin into the storage portion 22 (urethane in this embodiment) is performed (step S280). The detection element body 40 and the electronic circuit board 70 are molded with urethane. In FIG. 13, the resin molded resin is not drawn. Then, a gas containing gasoline vapor whose concentration is detected by another detection device is introduced into the measurement chamber 28, the gas sensor 10 is operated, and the output is calibrated (step S290). In this embodiment, the calibration of the gas sensor 10 is based on the detection result,
The calibration curve showing the relationship between the output of the gas sensor 10 and the gasoline concentration detected by another measuring device was obtained, and the calibration curve was written in the EEPROM incorporated in the microprocessor 91. It may be performed by adjusting a trimmer or the like prepared on the circuit board 70. In the latter case, it is desirable to provide an opening for inserting an adjustment tool in the case 80 and perform the adjustment with the case 80 attached (state in which resin molding has not been performed).

According to the method of manufacturing the gas sensor described above, the metal plate 36 is arranged at the bottom of the housing portion 22 when the flow path forming member 20 is formed of the synthetic resin using the technique of insert molding. The detection element body 40 and the electronic circuit board 70 can be easily arranged in the space surrounded by the case 80 electrically connected to the detection element body 40. Therefore, it is possible to achieve both ease of manufacturing and ensuring the effect of the electromagnetic shield on the functional component as the sensor.

(G) Second Embodiment: FIG. 14 is a sectional view showing the structure of a gas sensor according to a second embodiment of the present invention. In this gas sensor, the thermistor 60
It is different from the first embodiment in that it is provided on the side surface of. However, the thermistor insertion hole 25a (temperature measurement chamber) is integrally formed with the measurement chamber 28 and the circuit board storage chamber 23a by the flow path forming member 20a, which is the same as in the first embodiment. Further, the terminals 55a and 55b of the detection element body 40a, the terminals 64a of the thermistor 60,
It is also the same as the first embodiment in that it is connected to the electronic circuit board 70 in a state in which 64b and the 64b are arranged in parallel along the same direction. In order to realize such an arrangement, in the second embodiment, the electronic circuit board 70 is arranged in parallel in the longitudinal direction of the measurement chamber 28.

Like the gas sensor of the first embodiment, the gas sensor of the second embodiment also has a simplified electrical connection structure between the thermistor 60 and the electronic circuit board 70, and when assembled, the thermistor 60. And the detection element body 40a can be electrically connected to the electronic circuit board 70 almost at the same time. Further, even if the airtightness of the thermistor 60 is slightly lowered, the gas does not immediately leak to the outside, and the leak is prevented by the filler (not shown) in the electronic circuit board housing chamber 23a. There is an advantage.

In the second embodiment, the temperature measuring chamber 25a
Since it faces the measurement chamber 28, there is an advantage that the temperature measurement error has less influence on the concentration measurement error as compared with the first embodiment. On the other hand, in the first embodiment, the temperature measuring chamber 25 is provided at a position different from the measuring chamber 28, and the measuring chamber 2
Since there is no unevenness for the thermistor 60 in 8, the liquid and the like can be prevented from staying in the measurement chamber, and as a result, the accuracy of sound velocity measurement is improved, which is more preferable than the second embodiment.

Although some embodiments of the present invention have been described above, the present invention is not limited to these embodiments and can be modified within the scope not changing the gist of the present invention. .

For example, the present invention can be applied to a specific heat sensor using ultrasonic waves, or a sensor for detecting various properties of gas by a method other than ultrasonic waves. That is, the present invention has a characteristic detecting element for detecting a predetermined characteristic of gas, and a temperature detecting element for detecting the temperature of the gas, and has a predetermined characteristic and temperature of the predetermined gas of the gas. Accordingly, it is applicable to a gas sensor for detecting the property of gas.

Further, in the present embodiment, the temperature measuring chamber 25 is designed to have a circular sectional shape in the direction orthogonal to the axial direction of the thermistor 60, and the inner diameter φa and the temperature measuring chamber 25 are designed.
The proper position of the thermistor 60 was specified using the ratio b / φa of the distance b from the inlet of the thermistor 60 to the heat-sensitive portion 61 of the thermistor 60, but if the cross-sectional shape of the temperature measuring chamber 25 is not circular, its area is The effective inner diameter φa ′ may be calculated from D and applied. Further, the heat-sensitive portion 6 in the thermistor 60
When the position of 1 is recessed from the outer end of the thermistor 60, the effective distance b ′ may be similarly calculated and applied. Here, the effective inner diameter and distance are the introduction path 2
7, it can be defined as a value to be converted with reference to the time taken for the gases having different temperatures reaching the inlet of the temperature measuring chamber 25 to reach the heat-sensitive portion 61.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a schematic configuration of a gas sensor 10 of an embodiment.

FIG. 2 is a cross-sectional view showing the structure of the gas sensor 10.

FIG. 3 is a cross-sectional view showing a structure of a detection element body 40.

FIG. 4 is a sectional view showing a structure of a thermistor 60.

5 is an explanatory diagram showing an electrical configuration inside the electronic circuit board 70. FIG.

FIG. 6 is an explanatory diagram illustrating the principle of gas concentration detection using ultrasonic waves.

FIG. 7 is an enlarged sectional view showing the periphery of the thermistor 60 and the temperature measuring chamber 25.

FIG. 8 is a graph showing a relationship between an error in temperature measurement and an error in concentration measurement.

FIG. 9 is a graph showing the influence of the dimensional ratio b / φa related to the thermistor 60 on the temperature measurement error.

FIG. 10 is an explanatory diagram showing the influence on the concentration measurement error when the gas temperature changes, with respect to the ratio b / φa.

FIG. 11 is a process drawing showing the manufacturing method of the gas sensor 10 in the example.

FIG. 12 is an explanatory diagram showing a state in which the detection element body 40 is assembled into the storage portion 22 of the flow path forming member 20.

FIG. 13 is an explanatory diagram showing how the electronic circuit board 70 and the case 80 are attached.

FIG. 14 is a cross-sectional view showing the configuration of the gas sensor of the second embodiment.

FIG. 15 is a sectional view showing an example of the structure of a conventional gas concentration sensor 100.

[Explanation of symbols]

10 ... Gas sensor 20 ... Flow path forming member 22 ... Storage section 23 ... Circuit board storage room 24 ... Recess 25 ... Thermistor insertion hole (temperature measurement chamber) 27 ... Introduction route 28 ... Measuring room 29 ... Bypass channel 31 ... Connector 31d ... Terminal 32 ... Introduction hole 33 ... Reflector 34 ... Exit 35 ... Discharge channel 36 ... Metal plate 40 ... Detection element body (sound velocity detection element assembly) 41 ... Flange 42 ... Element case 43 ... Housing section 45 ... End face 46 ... Step 48 ... Protective film 50 ... Acoustic matching plate 51 ... Piezoelectric element 52 ... Cylindrical body 52a ... Polyethylene terephthalate film 52b ... Adhesive layer 52c ... Copper foil 54a, 54b ... Lead wire 55a, 55b ... Metal terminal 56a, 56b ... Projection 59 ... Protrusion 60 ... Thermistor (thermistor assembly) 61 ... Thermal part 62, 63 ... Holder 64a, 64b ... Metal piece terminal 65a, 65b ... Lead wire 66a, 66b ... Insulating sheath 70 ... Electronic circuit board 72 ... Mounting hole 80 ... Case 83 ... Cut and raised part 85 ... insertion hole 88 ... cushioning material 90 ... Timer 91 ... Microprocessor 92 ... D / A converter 93 ... Driver 96 ... Amplifier 97 ... Comparator 100 ... Gas concentration sensor 110 ... Flow path forming member 120 ... Measuring room 130 ... Circuit board storage room 140 ... Piezoelectric element 150 ... Circuit board 160 ... Temperature sensor 170 ... passage

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideki Ishikawa             14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi Japan special             Within Toyo Co., Ltd. (72) Inventor Keigo Banno             14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi Japan special             Within Toyo Co., Ltd. (72) Inventor Takeo Sasanamu             14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi Japan special             Within Toyo Co., Ltd. (72) Inventor Noboru Ishida             14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi Japan special             Within Toyo Co., Ltd. F term (reference) 2G047 AA01 BA03 BC02 BC15 EA10                       EA14 GA01 GA03 GA18 GG43                       GJ19

Claims (10)

[Claims] 1. A gas sensor for detecting a property of the gas according to a predetermined property and temperature of the gas, wherein the property detection element detects a predetermined property of the gas, and the property detection element is electrically connected to the property detection element. Characteristic detecting element assembly having a first metal piece terminal electrically connected, a temperature detecting element detecting the temperature of the gas, and a second metal piece terminal electrically connected to the temperature detecting element. And a circuit board electrically connected to the characteristic detection element and the temperature detection element via the first and second metal piece terminals, respectively. The assembly and the temperature detecting element assembly are installed so as to be respectively connected to the circuit board in a state where the first and second metal piece terminals are arranged in parallel along the same direction. Special The gas sensor to be. 2. The gas sensor according to claim 1, further comprising: a characteristic measuring chamber for detecting a predetermined characteristic of the gas by using the characteristic detecting element; and a characteristic measuring chamber for detecting the characteristic of the gas by using the temperature detecting element. A gas sensor for detecting a temperature, comprising: a temperature measuring chamber provided at a position different from the characteristic measuring chamber in the middle of the gas flow path in the gas sensor. 3. The gas sensor according to claim 2, further comprising a circuit board housing chamber for housing the circuit board, wherein the circuit board housing chamber, the characteristic measuring chamber, and the temperature measuring device. The chamber and the gas flow passage are integrally formed of resin so that the circuit board storage chamber and the characteristic measurement chamber and the circuit board storage chamber and the temperature measurement chamber communicate with each other. The characteristic detecting element assembly is fixed in a state that seals between the circuit board housing chamber and the characteristic measuring chamber, and the temperature detecting element assembly. Is a gas sensor fixed in a state of sealing between the circuit board housing chamber and the temperature measuring chamber. 4. The gas sensor according to claim 2 or 3, wherein the temperature measurement chamber is formed as a concave portion provided facing a flow path of the gas in the gas sensor. The ratio of the distance from the entrance of the recess facing the road to the tip of the temperature detecting element and the inner diameter of the recess is 0 to
A gas sensor set to a range of 2.0. 5. The gas sensor according to claim 2, further comprising a bypass flow path that bypasses the characteristic measurement chamber so that a larger amount of gas passes through the characteristic measurement chamber. A gas sensor, wherein the temperature measuring chamber is provided at a position facing the bypass flow path. 6. The gas sensor according to claim 1, wherein the characteristic detection element is an element that detects a propagation velocity of ultrasonic waves of the gas, and the gas sensor is the A gas sensor, which is a sensor that detects the concentration of at least one type of gas component contained in the gas according to the propagation velocity of a sound wave and the temperature of the gas. 7. A gas sensor for detecting a property of the gas according to a predetermined property and temperature of the gas, the gas sensor being provided facing a property measuring chamber into which the gas for detecting the property flows. A characteristic detecting element for detecting a predetermined characteristic of the gas in the characteristic measuring chamber, and a temperature detecting element for detecting the temperature of the gas in a temperature measuring chamber provided facing the flow path of the gas flowing into the characteristic measuring chamber, A circuit for processing the output of the characteristic detection element using the output of the temperature detection element and calculating at least a parameter relating to the property of the gas, wherein the temperature detection element has a tip at the temperature A gas sensor arranged at a position that does not protrude from the entrance of the measurement chamber. 8. The gas sensor according to claim 7, wherein a position of the temperature detection element is a ratio of a distance from an inlet of the temperature measurement chamber to a tip of the temperature detection element and an inner diameter of the temperature measurement chamber. Is set as a position in the range of 0 to 2.0. 9. The temperature measuring chamber is provided at a right angle to a flow direction of the gas in the flow path.
Alternatively, the gas sensor according to claim 8. 10. The gas sensor according to claim 7, wherein an outer diameter of the temperature detecting element is 1/2 or less of an inner diameter of the temperature measuring chamber.