JP2003302387A - Element housing unit, sensor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an element housing unit which can simplify steps of assembling and the like by housing an element such as an ultrasonic element or the like and which has high reliability. <P>SOLUTION: A detecting element body 40 houses a piezoelectric element 51 in a housing part 43 of a case 42. Lead wires 54a, 54b from its electrode are respectively soldered to terminals 55a, 55b insert molded in the part 43. Thereafter, the part 43 is filled with urethane resin. As a result, the wires 54a, 54b mounted at the element 51 are not disconnected by mistake at assembling time. Since the part 43 of the case 42 is formed thinly at a flange 41 side, even when the filled urethane is thermally expanded so that a stress is generated in the case 42, the part 43 of the case 42 is deformed to prevent an internal stress from being stored. As a result, a useless stress is not applied to the element 51, and hence its reverberation can be reduced. <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 an element housing body in which an element for exchanging ultrasonic waves and electric signals is housed in a case, and at least a portion where the element is present is filled with a filling material, and the same. The present invention also relates to a manufacturing method, and further to a sensor using the element housing and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, an element for exchanging ultrasonic waves and electric signals is housed in a case and used as a sensor or an ultrasonic wave generator. Ultrasonic waves propagate in various media, and the state of their propagation is affected by the properties of the media, such as the concentration and thickness of the media, the temperature, and so on, so they are used as sensors using ultrasonic waves. For example, a gas sensor is known in which an ultrasonic wave generator is provided at a position facing the flow path, and the concentration, temperature, or humidity of the gas existing in the flow path is detected. 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 the 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 speed 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 on an automobile to an intake pipe of an internal combustion engine, and a passage of a predetermined volume formed on the sensor is connected to an evaporated fuel containing gasoline or the like. It is configured to allow gas to pass. When the concentration of gasoline vapor changes, the speed of the ultrasonic wave passing through the medium changes, so this change is detected by the ultrasonic receiver, the signal is processed and output as a signal corresponding to the gasoline concentration. is there. Normally, the gasoline concentration is obtained by detecting the time required for the ultrasonic wave output from the transmitter to propagate through a predetermined distance and reach the receiver.

There are few elements such as such a gas concentration sensor that can directly convert a change in gas properties into a large electric signal, and the electric signal output from the detection element is often weak. Therefore, in the conventional gas sensor, an electric signal from the detection element is taken out to the outside through a lead wire or the like, and amplified and processed by a dedicated signal processing circuit.

[0004]

However, in general,
The element that exchanges ultrasonic waves and electric signals is a piezoelectric ceramic, etc., and its electrodes are only connected with thin wires by welding or soldering, which poses the problem of being difficult to handle. It was A thin wire lead wire is easily broken during assembly and is difficult to handle when connecting to a signal processing circuit. Alternatively,
It was also considered that the joint portion of the lead wire might come off due to vibration or the like during use.

An object of the present invention is to solve the above problems, to provide an element housing which is easy to handle and is easy to manufacture such as assembling.

[0006]

Means for Solving the Problem and Its Action / Effect The element housing of the present invention which solves at least a part of the above-mentioned problems, accommodates at least an element for exchanging ultrasonic waves and electric signals in a case, and An element container in which a portion where the element is present is filled with a filling material, wherein the case has a terminal for exchanging the electric signal with an external circuit, and the element is provided before the filling material is filled. And a lead wire that completes electrical connection between one end of the terminal and the terminal, and the lead wire and the location of the connection between the lead wire and the terminal are filled with the filler, and the terminal The gist is that the other end of is projected outward from the case.

In such an element container, a case for accommodating the element has a terminal, and the element is connected to the terminal by a lead wire. After the connection between the terminal and the lead wire is completed, the part where the element is present and the lead wire, and the part where the lead wire and the terminal are connected are sealed by the filling material. Therefore, the lead wire is not accidentally cut at the time of handling as an element housing. Moreover, since the other end of the terminal protrudes from the case to the outside, connection between the element housing and the outside may be performed using this terminal, and the element housing can be easily handled and assembled.

The case of such an element housing can be molded of synthetic resin. In this case, the terminal can be insert-molded in a case made of synthetic resin. Of course, the terminal may be attached to the case of synthetic resin by a method such as press fitting, but if it is insert-molded, the manufacturing becomes easier. In addition, the terminals are unlikely to fall off due to vibration during use.

As for the shape of such an element housing, the case may be composed of a tubular main body, a flange portion connected to one end of the main body, and a sealing member for sealing the other end of the main body. it can. By adopting such a configuration, it becomes easy to attach the element or other elements of the entire element housing. Further, in such a shape, if both ends of the terminal, which are connected to the lead wire, are projected from the inner peripheral surface of the main body of the case and the other end side is projected from the flange portion of the case, the lead wire This is preferable because the connection distance can be shortened. Further, since the other end of the terminal can be projected outward by the flange portion, connection from the element housing to an external device becomes easy.

In the structure having such a flange portion, the main body of the case may be formed in such a shape that the wall thickness increases from the flange portion side toward the side where the sealing member is present. In this case, since the terminal can be firmly held by the thickened portion, it is possible to satisfy the demand for ensuring the thickness for embedding the element in the main body. On the other hand, when the main body receives stress due to thermal expansion of the filler, for example, the main body is likely to be deformed to the outside in the vicinity of the joint portion with the thin flange portion, so the stress is released and the main body is released. Generation of internal stress can be suppressed.

If the case is conductive, the case itself may be used as a signal line for exchanging electrical signals with the outside, and the number of terminals may be one. However, if the case is made of synthetic resin having high insulation properties, Since the case cannot be used as a conductor, two signal lines are usually required for exchanging electrical signals. At this time, at least two terminals are provided, and they are respectively connected to different electrodes of the element. In this case, the two or more terminals may be provided symmetrically with respect to the axial center of the case body, or may be provided adjacent to the case body.
In the former configuration, the distance between the terminals can be sufficiently set, and thus the insulating distance between the terminals can be set large. On the other hand, if the latter configuration is adopted, the shape of the terminal of the element becomes asymmetrical, and therefore, if the terminal has a polarity, it cannot be mistakenly installed in the opposite direction. Further, there is an advantage that the signal lines can be easily routed when the signal from the terminal is connected to the input of the differential amplifier or the like.

The other end of the terminal projecting from the case may be directly connected to a signal processing circuit board for processing an electric signal from the element. If the terminal projects from the flange of the element housing, it is easy to provide the signal processing circuit board above the terminal, and the connection between the two can be simplified.

A sensor can be constructed using the above-mentioned element housing. That is, the sensor of the present invention is a sensor provided with a signal processing circuit board for processing a signal from an element housing, wherein the element receives an ultrasonic wave and generates an electric signal corresponding to the received ultrasonic wave. It is an element that functions as a receiver that outputs a signal, and the gist is that the other end of the terminal protruding from the element housing is directly connected to the signal processing circuit board.

Such a sensor is composed of an element housing and a signal processing circuit board for processing a signal from the element housing, and both of them are directly connected by the terminals of the element housing, so that the assembly is easy. The advantage is that it is present and highly reliable.

On the other hand, the invention of the method of manufacturing the element housing of the present invention is a method of manufacturing an element housing in which an element for exchanging ultrasonic waves and electric signals is housed in a case, wherein the case is , A terminal for exchanging the electric signal with an external circuit, one end of which protrudes inside the case,
The other end of the terminal is formed by insert molding into a shape protruding to the outside of the case, the element is arranged in the case, and then the element and one end of the terminal are electrically connected by a lead wire. Further, the gist of the present invention is that at least the portion where the element and the lead wire are present is filled with a filling material.

According to the method of manufacturing the element housing, in the case for housing the element, the terminal for exchanging an electric signal with an external circuit has one end protruding inside the case and the other end protruding outside the case. It is insert-molded into the desired shape. Then, after arranging the element in the case, the element and one end of the terminal are electrically connected by a lead wire. Since the terminals are insert-molded in the case,
Both can be connected easily. Moreover, since at least the portion where the element and the lead wire are present is filled with the filling material, in the element container manufactured by such a manufacturing method, the risk of disconnection of the lead wire can be reduced.

Further, according to the method of manufacturing a sensor of the present invention, an element housing in which an element for exchanging ultrasonic waves and electric signals is housed in a case, and a signal for processing the electric signal from the element housing. A method of manufacturing a sensor including a processing circuit board, comprising: a case for accommodating the element, a shape having an accommodating portion capable of accommodating the element, and a mounting flange portion of the accommodating portion. Molded from a synthetic resin in a shape continuous to one end, the case has a terminal for exchanging the electric signal with an external circuit, one end of which protrudes inside the accommodating portion of the case, After insert-molding the other end of the terminal into a shape projecting to the outside of the case, disposing the element in the housing portion of the case, electrically connecting the element and one end of the terminal, and At least the element The sites present in, and filled by the filling material, the other end of the pin projecting outwardly from said element housing, and summarized in that a direct connection to the signal processing circuit board.

According to the sensor manufacturing method, the sensor is composed of an element housing containing an element for exchanging ultrasonic waves and electric signals, and a signal processing circuit board for processing the electric signals from the element housing. Reduces the labor of manufacturing
Moreover, the reliability of the manufactured sensor can be improved.

[0019]

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 an embodiment of the present invention. This gas sensor 1
0 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 10: As shown in FIG. 1, the gas sensor 10 is roughly composed of a flow path forming member 20 forming a flow path through which a gas whose concentration is to be detected passes. The detection element main 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 main body 40 are arranged above the detection element main body 40. Electronic circuit board 7
0, it is composed of a metal case 80 which is fitted into the storage portion 22. The detection element body 40 is fixed to the mounting recess 24 provided in the housing 22 by ultrasonic welding, and the thermistor 60 has the mounting insertion hole 2 for mounting.
It is inserted and fixed in 5. As will be described later, the detection element body 40 and the thermistor 60 have terminals for exchanging electrical signals, and these terminals are used for the electronic circuit board 7.
It is inserted into the corresponding mounting hole of 0 and fixed by soldering. In the gas sensor 10, after fixing the detection element body 40 and the thermistor 60 to the housing portion 22, an electronic circuit board 70, which is a board that performs signal processing, is attached,
Further, the case 80 is fitted in the housing portion 22, and the whole is molded with a resin such as urethane, and is manufactured. Regarding the manufacturing process of the gas sensor 10,
This will be described in detail in (G).

(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 tensile elastic modulus is adjusted to an appropriate value as a gas sensor. Has been done. As shown in FIG. 1, the flow path forming member 20 includes a storage portion 22 that stores the detection element body 40 in the upper portion, and has a flow passage through which the detection gas flows in the lower portion. As the main flow path,
An introduction path 27 for introducing a gas containing gasoline vapor to the gas sensor 10, a measurement chamber 28 for ultrasonically detecting the gasoline concentration in this gas, and a bypass flow path 29 for bypassing the gas to the measurement chamber 28 are formed. ing. The measurement chamber 28 is located immediately below the detection element body 40.
The bypass flow paths 29 are provided substantially directly below the thermistor 60.

In order 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 to which is attached, and a reflecting portion 33 for reflecting an ultrasonic wave is formed below the concave portion 24. Although the function of the reflecting portion 33 will be described later, the reflecting portion 33 has a structure in which it is lifted by a predetermined distance (several millimeters in this embodiment) from the bottom of the measuring chamber 28.
The void around the area is directly connected to the bypass flow path 29 via the discharge flow path 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 measurement 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 shape that substantially follows the shape of the bottom surface of the storage section 22. The metal plate 36 is provided with a cut-and-raised portion 83 for making an electrical connection. 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 attachment hole 72 on the board when the electronic circuit board 70 is attached. It A land connected to the ground line is prepared in the mounting hole 72, and the cut and raised portion 83 is
Solder to this land.

At one of the four corners inside the storage section 22 adjacent to the cut-and-raised portion 83, the electronic circuit board 7 is provided.
The terminal convex portion is provided also as a support table on which 0 is placed. A connector 31 for exchanging electrical signals is formed on the outer side, and a terminal forming the connector 31 penetrates the outer wall of the housing portion 22 at this portion.
The connector 31 is provided with three terminals on the entrance side, and two terminals on both sides of the three terminals are connected to a power supply line (ground and DC voltage) for supplying power to the gas sensor 10 from the outside. And the terminal GND and the terminal Vcc, and the center is the terminal SGNL connected to the signal output line from the gas sensor 10 (see FIG. 5). These connectors 31 have four terminals on the storage section 22 side. This is the terminal G for the ground line.
This is because the ND has a bifurcated shape on the way. One of the bifurcated terminals (terminal G in FIG. 5)
ND1) is connected and soldered to the electronic circuit board 70, and the other one (reference numeral G terminal 2 in FIG. 5) is extended upward, and when the case 80 is assembled, the correspondence of this case 80 Insertion hole 85 prepared at the position
(See FIG. 1). After insertion, the terminal is case 8
Soldered or brazed to zero. As a result, the entire case 80 is electrically coupled to the ground line. Of the corners of the storage part 22, the remaining two places are
A support base (not shown) is formed for the purpose of mounting the electronic circuit board 70.

(C) Structure of the detecting element body 40: The structure of the detecting element body 40 is shown in the sectional view of FIG. As shown in FIG. 1, the detection element main body 40 has a disk shape after assembly, and this has a piezoelectric element 51, which will be described later, inside a synthetic resin element case 42 having a flange portion 41.
This is because the urethane is filled inside after storing such items. The flange portion 41 of the element case 42 is formed to have a larger diameter than the mounting recess 24 provided in the housing portion 22, and the housing portion 43 below the flange portion 41 is formed to have a smaller diameter than the recess portion 24. In the state of the element case 42 alone, the lower surface of the housing portion 43 is opened, and a step portion 46 is formed at the outer edge portion of the end surface 45 thereof. 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 adhered and fixed to the center of the protective film 48, and a piezoelectric element 51 which is an ultrasonic element is adhered and fixed to the upper surface of the acoustic matching plate 50. . The acoustic matching plate 50 is provided to efficiently send the vibration of the piezoelectric element 51 into the air (to the measurement chamber 28 in this embodiment) via the protective film 48. Since sound waves and ultrasonic waves are likely to be reflected at a place where there is a difference in the density of the medium, the piezoelectric element 51 is not directly bonded to the protective film 48, but is bonded via the acoustic matching plate 50. The vibration of 51 can be efficiently transmitted as ultrasonic waves into the measurement chamber 28. In this embodiment, as the acoustic matching plate 50, a large number of small glass beads hardened with an epoxy resin is used. Also, to surround the acoustic matching plate 50 and the piezoelectric element 51,
A tubular body 52 is arranged. The tubular body 52 is obtained by laminating a copper foil 52c on a polyethylene terephthalate film 52a via an adhesive layer 52b.
The c side is the inner side, and it is wound in a cylindrical shape, and the end faces are overlapped and pasted together. The inner diameter of the cylindrical body 52 is equal to the acoustic matching plate 5
The cylindrical body 52 is in close contact with the outer periphery of the acoustic matching plate 50, because the cylindrical body 52 has an outer diameter substantially equal to 0. The two are not glued.

The piezoelectric element 51 is formed by forming an electrostrictive element such as a piezo into a cylindrical 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 outer diameter of the piezoelectric element 51 is the same as that of the acoustic matching plate 5.
It is smaller than the outer diameter of 0. Therefore, between the inner surface of the cylindrical body 52 surrounding this and the side surface of the piezoelectric element 51,
A gap will be formed. Cylindrical body 52 and acoustic matching plate 5
The relationship between 0 and the piezoelectric element 51 is shown in FIG. Figure 4
FIG. 6 is an exploded perspective view showing a relationship among the acoustic matching plate 50, the piezoelectric element 51, and the cylindrical body 52. As shown in the figure, the cylindrical body 52 is provided with twelve openings 53. This opening 53
Are provided at positions displaced upward along the axial direction of the piezoelectric element 51. Therefore, after the assembly, the opening 53 of the cylindrical body 52 is not on the outer periphery of the acoustic matching plate 50, but on the piezoelectric element 5.
It exists at a position corresponding to the outer circumference of 1. In addition,
In FIG. 4, for convenience of understanding, the layers 52a, 52b, 52c forming the tubular body 52 are integrally drawn.

The element case 42, as shown in FIG.
The cross section has a substantially inverted "L" shape, and the inner peripheral surface thereof is tapered at a predetermined angle (about 11 degrees in this embodiment) with respect to the vertical plane. Therefore, the portion corresponding to the outer wall of the housing portion 43 increases in thickness as it approaches 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,
Only the portions where the terminals 55a and 55b are embedded have a shape protruding inward. Terminals 55a and 55b are insert-molded on the protrusions 56a and 56b. The terminals 55 a and 55 b are bent in an “L” shape, and the lower ends thereof project to the inner surface of the housing portion 43. Lead wires 54a and 54b are soldered to the lower end. After the lead wires 54a and 54b of the piezoelectric element 51 have been attached in this way, the inside of the element case 42 is filled with urethane. The upper ends of the terminals 55a and 55b project upward from the upper surface of the element case 42. These terminals are inserted into the corresponding mounting holes of the electronic circuit board 70 when the electronic circuit board 70 is mounted on the upper portion thereof, and are soldered to the lands prepared at that location.

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 storage section 22.

(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, as described above, the detection element body 40, the thermistor 60, or the terminals of the connector 31, the cut-and-raised parts 83, and the like are provided with mounting holes having sizes corresponding to the respective terminal shapes. , The land pattern surrounds it. Therefore, the completed electronic circuit board 70 has various parts for signal processing, such as an integrated circuit (IC) for signal processing, resistors, capacitors, etc., attached at predetermined positions, which are used for detection. The electrical circuit configuration is completed by mounting the element body 40 and the thermistor 60 in the housing 22 where the mounting is completed and performing soldering. The gas sensor 10 is finally manufactured by resin molding, which will be collectively described later in the section of the manufacturing method.

When various terminals are soldered to the electronic circuit board 70, the outermost terminal GND2 (see FIG. 5) among the terminals of the connector 31 does not have the corresponding land on the electronic circuit board 70 and the terminal GND2 is an electronic circuit board 70
It only passes through the through hole provided in the. The terminal GND2 passes through a through hole provided in the electronic circuit board 70 and is inserted into the insertion hole 85 of the case 80, where it is soldered or brazed to the case 80.

The electrical configuration 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, and each circuit element connected to the microprocessor 91, that is, a digital-analog converter (D / A converter) 92, a driver 93, an amplifier 96.
Are connected to the comparator 97 and the like. 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 driver 93 is a circuit which receives a command from the microprocessor 91 and drives the piezoelectric element 51 of the detection element body 40 for a predetermined time. This driver 93
Receives a command from the microprocessor 91 and outputs a plurality of rectangular waves. 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. The output of the amplifier 96 is input to the comparator 97,
Here, it is compared with a threshold value Vref prepared in advance. Threshold V
ref is a level capable of discriminating an erroneous signal output from the amplifier 96 due to the influence of noise or the like. 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 the vibration received by the piezoelectric element 51 exceeds a predetermined level. The output of the comparator 97 is monitored by the microprocessor 91, and the time Δt 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, 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 medium follows the following equation (1).

[0039]

[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 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. In this embodiment, the concentration of gasoline vapor was detected, but if the concentration is known, it can be used as a sensor for obtaining the temperature T and the propagation 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 is output to the outside via the terminal SGNL of the connector 31. In the embodiment, this terminal SGNL is connected to a computer (ECU) that controls the fuel injection amount of the internal combustion engine, and the signal corresponding to the gasoline concentration is EC
It is read by U and is used for processing such as correcting the fuel injection amount in consideration of the purge amount of gasoline from the canister. Although lines related to the power supply are not shown in FIG. 5, a power supply line for supplying a DC voltage Vcc and a ground (ground line) are connected to each element including the microprocessor 91. Has been done. 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 and the case 80 (see FIG. 1) are combined with each other to form a box body that covers the detection element body 40 (see FIG. 2). (See), because this is kept at the same potential, it has realized an electromagnetic shield electrically. Therefore, the detection element body 40 and the electronic circuit board 70 housed inside are effectively protected against noise from the outside.

(E) Operation / Effect of Embodiment: According to the gas sensor of this embodiment described above, the concentration of gasoline vapor in the gas introduced into the measurement chamber 28 of the flow path forming member 20 is determined by using ultrasonic waves. Can be detected accurately. The detection element body 40 uses a piezoelectric element 51 as an element for exchanging ultrasonic waves and electric signals, and its lead wires 54a and 54b are extremely thin.
Rather than connecting a and 54b to the electronic circuit board 70 by routing them, these are soldered to the lower ends of the terminals 55a and 55b, and the piezoelectric element 51 and the lead wires 54a and 54b are filled with urethane resin. As a result, the detection element body 4
When assembling 0, the lead wires 54a and 54b are not accidentally cut. Moreover, the detection element body 40
As for the exchange of electrical signals, the terminal 55
Since a and 55b are used, they are easy to handle and easy to assemble.

Further, in this embodiment, the detecting element body 40 is used.
The case 42 has a wall thickness that is thin on the flange portion 41 side and thick on the film 48 side in the housing portion 43.
Therefore, for example, even if the temperature of the urethane resin filled in the accommodating portion 43 rises and thermally expands, and stress is generated inside the element body, the wall thickness of the connecting portion with the flange portion 41 is thin. Therefore, there is an advantage that it is deformed here and stress is less likely to be accumulated inside. In fact, the case 42 is made of metal,
If the outer wall of the accommodating portion 43 is not deformed, the film 48 receives internal stress and projects toward the measurement chamber 28 when the urethane resin thermally expands. When the wall thickness is reduced on the flange portion 41 side, the accommodating portion 43 is deformed, so that the film 48
The amount of protrusion of the above to the measurement chamber 28 side is reduced. It has been observed that when the accumulation of the internal stress is reduced in this way, the influence of the stress acting on the piezoelectric element 51 is reduced, and the influence of the reverberation in the piezoelectric element 51 is also reduced. Moreover, in this embodiment, the wall thickness of the entire housing portion 43 is not thin, but is thick on the film 48 side. Therefore, the wall thickness is sufficient to insert-mold the terminals 55a and 55b. Can be secured.

(F) Modification: Another modification of the present invention will be described. 7A and 7B are sectional views showing the shape of the first modification of the detection element body. The element main body 40A in this modified example has substantially the same configuration as that of the above-described embodiment, but the wall thickness of the housing portion 43A is the same as that of the flange portion
The one side and the film 48 side are the same. Further, the wall thickness is a thickness necessary for insert molding the terminals 55a and 55b. Also in this modified example, the lead wires 54a and 54b are soldered to the lower ends of the terminals 55a and 55b, which facilitates the assembly of the element body and leads 54a and 54b.
The effect of preventing the disconnection of 54b is similarly obtained.
In addition, the flange portion 4 is provided against the thermal expansion of the urethane resin.
The case 42 is made of synthetic resin, though the effect of reducing the thickness is not obtained as in the above-mentioned embodiment in which one side is thin.
Due to the deformation, the stress is somewhat reduced.
Of course, if a soft resin such as a phenolic resin is used, the case 42 having the shape shown in FIG. 7 can be deformed according to the thermal expansion of the urethane resin, and the internal stress can be sufficiently reduced.

Of course, as shown in FIG. 7 (B), a groove 49 is provided in a part of the accommodating portion 43B, and the accommodating portion 43B is here
It is also possible to adopt a configuration in which the deformation of (1) easily occurs. When the groove 49 is provided in the accommodation portion 43B over the entire circumference, the insert-molded terminal 55a, depending on the depth of the groove,
It is possible that part of 55b is exposed at this part,
Since it is inside the element body 40B and is filled with urethane resin, no particular problem occurs.

FIG. 8 shows a second modification. The configuration of this modification is almost the same as that of the above-described embodiment, and only the shape of the terminal is different. In the detection element body 40C according to this modification, the lower ends of the terminals 55c and 55d not only simply project inside the housing portion 43C, but also extend in the direction in which the piezoelectric element 51 exists. Therefore, the lower ends of the terminals 55c and 55d have short lead wires 54
With c and 54d, the electrodes can be soldered and electrically connected to the electrodes of the piezoelectric element 51. In this case, the lengths of the lead wires 54c and 54d can be shortened, and the possibility of disconnection accidents that are likely to occur due to the long lead wires being routed can be reduced.

Further, a third modification is shown in FIG. In the detection element body 40D of this example, the terminals 55a and 55b are provided not at the positions adjacent to each other, but at positions that are substantially opposite to each other. Therefore, the element body 40D is excellent in symmetry, the lead wires 54a and 54b can have the same length, and the mass distribution of the element body 40D can be substantially symmetrical. Therefore, even if the ultrasonic wave transmitted from the piezoelectric element 51 leaks in the radial direction of the element, the behavior is considered to be in contrast, and the reverberation is reduced. In addition, since the distance between the terminals 55a and 55b can be widened, it is possible to reduce the electrostatic capacitance between the parallel terminals 55a and 55b, and it is also possible to obtain the advantage that noise due to the electrostatic capacitance is less likely to travel. .

(G) Method of manufacturing gas sensor: Next, with respect to a method of manufacturing the gas sensor 10 in this embodiment,
explain. FIG. 10 is a process drawing showing the manufacturing process of the gas sensor. As shown in the figure, when manufacturing the gas sensor 10, an operation of assembling the piezoelectric element is first performed (step S100). In this step, as shown in FIG. 11, the protective film 48 is cut into a predetermined shape (circular in the embodiment), and the acoustic matching plate 50 is bonded to the center thereof. Further, the piezoelectric element 51 is adhered on it with its center aligned. At this time, a jig may be used to align the centers. FIG. 11 (A) shows the state during adhesion, and FIG. 11 (B) shows the state after adhesion. As shown in the figure, after bonding, the piezoelectric element 5
Lead wires 54a and 54b are connected to the first electrode by a method such as soldering or discharge welding.

On the other hand, an element case 42 for enclosing the piezoelectric element assembly thus obtained is prepared (step S110). As shown in FIG. 12A, the element case 42 is manufactured by injection molding a synthetic resin containing glass filler. Of course, a method such as shaving may be used. Element case 4
Terminals 55a and 55b are insert-molded on the protrusions 56a and 56b provided on the inside of 2.

Next, the work of assembling the detection element body is performed (step S120). In this step, first, step S
The piezoelectric element assembly assembled in step S100 is assembled to the element case 42 manufactured in 110. This work is shown in Figure 1.
As shown in FIG. 2B, the piezoelectric element is assembled by attaching the outer periphery of the protective film 48 to the lower end surface 45 of the element case 42 with an adhesive and fixing the same. Since the step portion 46 is provided on the outer circumference of the end surface 45, it is easy to position and adhere the protective film 48 to the end surface 45. In this state, as shown in FIG.
2 is inserted from the opening side of the element case 42 and fitted into the outer periphery of the acoustic matching plate 50 (step S130).
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. The tubular body 52 is not attached to the acoustic matching plate 50, and 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, as shown in FIG. 13B, 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). At this time, the urethane as the filler covers the piezoelectric element 51 and the lead wires 54a and 54b pulled out from the upper end thereof,
Moreover, the filling is performed to the extent that it does not reach the upper side of the flange portion 41. The state after filling is shown in FIG.

The flow path forming member 20 is manufactured separately from the manufacturing of the detecting 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 S).
200). The metal plate 36 used in the present embodiment is integrally formed by pressing a substantially rectangular metal plate (tin-plated steel plate in the embodiment).

Then, the flow path forming member 20 is subjected to insert molding 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. The metal plate 36 is
At the time of molding the flow path forming member 20, it is held at a position to be embedded in the bottom portion of the storage portion 22 after being formed by using a jig or the like.
At the same time, the terminals housed in the connector 31 are also insert-molded.

After the flow path forming member 20 is manufactured in this way,
The operation of welding the already-manufactured detection element body 40 to the housing portion 22 of the flow path forming member 20 is performed (step S230). The welding is performed by ultrasonic welding. This is performed by mounting the detection element body 40 on a predetermined jig, aligning the center of the detection element body 40 with the center of the recess 24, and then moving the detection element body 40 to a frequency in the ultrasonic region. Then, the lower surface of the flange portion 41 is strongly struck against the joint surface of the housing portion 22. 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 states before and after the attachment of the detection element body 40 are shown in FIGS. The welding may be based on another method such as hot plate welding.

Before and after the detection element body 40 is attached, the work of attaching the thermistor 60 to the insertion hole 25 of the flow path forming member 20 is also performed (step S240). Thereafter, the cushioning material 88 is placed on the detection element body 40 (step S
250). The cushioning material 88 is a foamed body formed to have substantially the same outer diameter as the detection element body 40, 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 has a thickness such that it can be interposed between the electronic circuit board 70 to be attached in the subsequent step and the detection element body 40, and urethane filled in the step described later is included in the detection element body 40. It is used for the purpose of not filling the surrounding area.

After arranging the cushioning material 88, as shown in FIG. 15A, the following four members are fitted into the mounting holes prepared on the electronic circuit board 70 while the board 70 is being fitted.
Is stored in the storage unit 22 from above (step S26).
0). 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 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 parts other than the terminals 31d of the connector 31 are soldered to lands provided around the mounting holes on the electronic circuit board 70.

Next, as shown in FIG. 15B, the work of attaching the case 80 to the storage section 22 is performed (step S270). At this time, the terminal 31d of the connector 31 is penetrated 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. Note that FIG.
Then, the resin used for the resin mold 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 the calibration of the gas sensor 10, in this embodiment, a calibration curve showing the relationship between the output of the gas sensor 10 and the gasoline concentration detected by another measuring device is obtained from the detection result, and the calibration curve is stored in the EEPROM 91 incorporated in the microprocessor 91. However, it may be performed by adjusting a trimmer or the like prepared on the electronic circuit board 70 before filling the urethane. 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 detection element body 40 has a configuration in which the upper ends of the terminals 55a and 55b are erected on the flange portion 41 side, and this is electrically connected to the electronic circuit board 70. Connection is easy. Since members such as lead wires that require careful handling are not exposed to the outside, there is an advantage that the assembly thereof is extremely simplified. In addition, since the manufactured detection element body 40 and the gas sensor 10 using the detection element body are less likely to have a disconnection failure, their reliability is sufficiently high.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments of the present invention at all, and a temperature sensor using ultrasonic waves, a temperature sensor using ultrasonic waves, or the like can be used without departing from the scope of the present invention. Of course, it can be applied to a sensor for detecting various properties of gas by a specific heat sensor or a method other than ultrasonic waves. Further, in the embodiment, the synthetic resin is used as the element case 42, but a metal case or a case made of another material such as wood or paper can be appropriately adopted.

[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 an exploded perspective view showing the structures of an acoustic matching plate 50, a piezoelectric element 51, and a cylindrical body 52.

5 is an explanatory diagram showing an internal electrical configuration of 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 explanatory diagram showing a first modification of the embodiment.

FIG. 8 is an explanatory diagram showing a second modification of the embodiment.

FIG. 9 is an explanatory diagram showing a third modification of the embodiment.

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

FIG. 11 is an explanatory diagram showing a state of piezoelectric element assembly.

FIG. 12 is an explanatory diagram showing a procedure of assembling the piezoelectric element assembly to the element case.

FIG. 13 is an explanatory diagram sequentially showing the process of manufacturing the detection element body 40.

FIG. 14 is an explanatory diagram showing a state in which the detection element body 40 is assembled into the housing portion 22 of the flow path forming member 20.

FIG. 15 is an explanatory diagram showing how the electronic circuit board 70 and the case 80 are attached.

[Explanation of symbols]

10 ... Gas sensor 20 ... Flow path forming member 22 ... Storage section 24 ... Recess 25 ... Insertion hole 27 ... Introduction route 28 ... Measuring room 29 ... Bypass channel 31 ... Connector 32 ... Introduction hole 33 ... Reflector 34 ... Exit 35 ... Discharge channel 36 ... Metal plate 40, 40A ... Detection element body 41 ... Flange 42 ... Element case 43, 43A ... Housing section 45 ... End face 46 ... Step 48 ... film 50 ... Acoustic matching plate 51 ... Piezoelectric element 52 ... Cylindrical body 52a ... Polyethylene terephthalate film 52b ... Adhesive layer 52c ... Copper foil 53 ... Opening 54a to 54d ... Lead wire 55a to 55d ... Terminal 56a, 56b ... Projection 59 ... Protrusion 60 ... Thermistor 70 ... Electronic circuit board 72 ... Mounting hole 80 ... Case 83 ... Cut and raised part 85 ... insertion hole 88 ... cushioning material

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Keigo Banno             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. (72) Inventor Takafumi Oshima             14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi Japan special             Within Toyo Co., Ltd. F term (reference) 2G047 AA01 BA03 BC02 BC15 CA01                       EA11 EA14 GA02 GA03 GB21                       GB28 GB32 GB35 GB36 GF06                       GG28 GG33                 5D019 AA20 AA26 EE02 FF01 GG09                       HH03

Claims (11)

[Claims] 1. An element container in which an element for exchanging ultrasonic waves and electric signals is housed in a case, and at least a portion where the element is present is filled with a filling material, the case comprising: A terminal for exchanging the electric signal with an external circuit, and having a lead wire for completing electrical connection between the element and one end of the terminal before filling the filling material, and the lead wire and the The location of the connection between the lead wire and the terminal is
An element container filled with the filling material, the other end of the terminal projecting outward from the case. 2. The element housing according to claim 1, wherein the case is formed by molding a synthetic resin, and the terminals are insert-molded in the case. 3. The element container according to claim 1, wherein the case has a tubular main body, a flange portion connected to one end of the main body, and the other end of the main body. An element formed of a sealing member for sealing, the side of the terminal connected to the lead wire protruding from the inner peripheral surface of the main body, and the other end of the terminal protruding from the flange portion. Containment body. 4. The element container according to claim 3, wherein the main body is formed in a shape in which the thickness increases from the side of the flange portion toward the side where the sealing member is present. 5. The element housing according to claim 1, wherein at least two terminals are provided and are respectively connected to different electrodes of the element. 6. The at least two terminals are respectively provided at symmetrical positions with respect to an axial center of the main body.
The described element container. 7. The element container according to claim 5, wherein the two or more terminals are provided adjacent to the main body. 8. The element housing according to claim 1, wherein the other end of the terminal projecting from the case is directly connected to a signal processing circuit board that processes an electric signal from the element. . 9. A sensor comprising the element housing according to claim 1 and a signal processing circuit board for processing a signal from the element housing, wherein the element is An element that functions as a receiver that receives a sound wave and outputs an electric signal corresponding to the ultrasonic wave, and the other end of the terminal protruding from the element housing is directly connected to the signal processing circuit board. Sensor. 10. A method of manufacturing an element housing in which an element for exchanging ultrasonic waves and an electric signal is housed in a case, wherein the case has terminals for exchanging the electric signal with an external circuit. One end of the terminal protrudes inside the case, and the other end of the terminal is formed by insert molding in a shape protruding outside of the case. After arranging the element in the case, the element and the terminal A method of manufacturing an element container, which is electrically connected to one end by a lead wire and further fills at least the portion where the element and the lead wire exist with a filler. 11. A sensor including an element housing in which an element for exchanging ultrasonic waves and electric signals is housed in a case, and a signal processing circuit board for processing an electric signal from the element housing. A method for molding the case into a shape having an accommodating portion capable of accommodating the element therein and a mounting flange portion continuously provided at one end of the accommodating portion, using a synthetic resin. Then, in the case, a terminal for exchanging the electric signal with an external circuit is insert-molded in such a shape that one end of the terminal projects inside the housing and the other end of the terminal projects outside the case, After arranging the element in the accommodating portion of the case, electrically connecting the element and one end of the terminal, filling at least a portion of the element in the accommodating portion with a filler, the element accommodating Out of the body Method for producing a sensor and the other end of the protruding terminal, directly connected to the signal processing circuit board.