JPH11148880A - Pressure transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure transmitter in which the inside of a case can be made to communicate with the open air and which can ensure a sufficient waterproof property and a sufficient dustproof property. SOLUTION: A pressure transmitter 5 is provided with a case 61 in which a pressure sensor 51 is housed, with a first connector part 62 which is integrated with the case 61 and with a second connector part 63 which can be fitted to, and removed from, the first connector part 62. In the pressure transmitter 5, the inside space of the case 61 is made to communicate with the open air via a through hole 64 in the first connector part 62, via a space between the first connector part 62 and the second connector part 63 and via a ventilation passage 67 in the second connector part 63. An opening 64A on the side of the case 61 in the through hole 64 is sealed with a filter 65 which is provided with a ventilation property and a waterproof property. Thereby, it is possible to prevent water, dust particles and the like from intruding and the ventilation between the inside and the outside of the case 61 can be ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure transmitter, and more particularly, to a pressure sensor for detecting a pressure difference between a detected pressure and an atmospheric pressure and converting it into an electric signal, and a case in which the pressure sensor is housed. The present invention also relates to a pressure transmitter including a first connector unit integrated with the case to hermetically seal the case, and a second connector unit provided in the first connector unit so as to be able to be fitted and detached from the first connector unit.

[0002]

2. Description of the Related Art A pressure transmitter that accommodates a pressure sensor that detects a pressure difference between a detected pressure and an atmospheric pressure and converts the pressure into an electric signal is used for measuring a fluid pressure. A pressure sensor having a structure using a diaphragm is known. That is, one surface of the diaphragm is a pressure-sensitive surface that receives the detected pressure, the other surface is an atmospheric pressure-receiving surface that receives the atmospheric pressure, and only the fluid to be measured is introduced into the pressure-sensitive surface, and the atmospheric pressure-receiving surface is applied. The surface is opened to the space in the case, whereby the diaphragm is deformed by the pressure difference between the detected pressure and the atmospheric pressure. As this type of pressure sensor, for example, a strain gauge type pressure sensor that converts the deformation of the diaphragm into an electric signal by a strain gauge, a capacitance type pressure sensor that detects the deformation of the diaphragm as capacitance, and the like are known. I have.

[0003] Wires such as signal cables and power cables are usually connected to such pressure transmitters. For this connection, a pair of connector parts that fit together are often used. That is, by integrating the case and the first connector portion, for example, the male connector portion, and fitting the second connector portion, specifically, the female connector portion provided with an electric wire, to the male connector portion. Connect the wires.

By the way, when the measurement environment in which the pressure transmitter is installed is severe, etc., in order to protect the pressure sensor,
The case has a sealed structure to improve the waterproof and dustproof functions. However, when the case is sealed, the pressure in the case fluctuates due to temperature changes and deformation of the diaphragm, and the pressure applied to the atmospheric pressure receiving surface is not the same as the atmospheric pressure.

In order to solve such a problem, a through hole is provided in the male connector portion to communicate with the inside of the case, and the through hole communicates with a gap in the electric wire of the female connector portion. There is a method in which the inside of the case is opened to the atmosphere while the connector portion is fitted (Japanese Utility Model Publication No. 7-49398).

[0006]

In this method, when the female connector is detached from the male connector, the through-hole of the male connector is exposed, so that water, dust, and the like enter the case through the through-hole. There is a problem that there is a possibility that the water may enter and sufficient waterproofness and dustproofness cannot be obtained.

An object of the present invention is to provide a pressure transmitter capable of communicating the inside of a case with the atmosphere and securing sufficient waterproofness and dustproofness.

[0008]

SUMMARY OF THE INVENTION The present invention has a pressure-sensitive surface for receiving a detected pressure of a portion to be measured and an atmospheric pressure receiving surface for receiving an atmospheric pressure, and detects a pressure difference between the detected pressure and the atmospheric pressure. Pressure sensor that converts the pressure into an electric signal, a case in which the pressure sensor is housed, a first connector unit that is integrated with the case and hermetically seals the case, and is detachable from the first connector unit. And a second connector provided in the first connector, wherein the first connector communicates a space between the first connector and the second connector with an internal space of the case. A through hole is provided, the second connector portion is provided with an air passage communicating from the space between the first connector portion and the second connector portion to the atmosphere, and the case-side opening of the through hole has air permeability and waterproofness. Having filter closed by It is characterized in that is.

According to the present invention, the internal space of the case is communicated with the atmosphere through the through hole of the first connector, the space between the first and second connector, and the air passage of the second connector. Therefore, ventilation inside and outside the case is ensured. Of these, the through-hole of the first connector portion is sealed by a filter having air permeability and waterproofness, so even if the through-hole is exposed in a state where the second connector portion is detached from the first connector portion, The filter can prevent water, dust, etc. from entering the case, and can introduce only air excluding water, dust, dust, etc., into the case, providing excellent waterproof and dustproof properties. Parts in the case including the can be reliably protected.

Since the filter is provided so as to seal the opening of the through hole on the case side, the entire filter is not exposed to the outside and is protected by the case and the first connector portion. Collision, adhesion of mud, pebbles, etc. to the filter can be prevented. Therefore, even when the measurement environment is severe, clogging of the filter due to adhesion of dust and the like can be prevented, and the air permeability can be continuously maintained.
Since the filter can be prevented from being damaged by dust or the like, the waterproofness of the filter can be maintained.

[0011] The above-mentioned filter is preferably provided with a connecting portion on a peripheral portion thereof, and the connecting portion is preferably ultrasonically welded to the opening end of the case side opening. When the connection portion of the filter is ultrasonically welded in this manner, the connection portion of the filter and the opening end of the case-side opening can be securely brought into close contact with each other without any gap in a short time.

Further, a lid member for covering the pressure sensor from the first connector portion side is press-fitted into the case, and a ventilation hole is formed in the lid member, and the lid member and the case are desirably made of metal. .

When such a cover member is provided, the pressure sensor and the first connector portion are shut off, so that even if dust, dirt, water, or the like enters through the through hole, it can be prevented from entering the pressure sensor. . On the other hand, since the air flow is hindered by the lid member, there is a possibility that the same pressure as the atmospheric pressure will not be applied to the atmospheric pressure receiving surface of the pressure sensor. Since air can be circulated between the pressure sensor and the first connector portion through the pores, the pressure received by the atmospheric pressure receiving surface can be reliably made equal to the atmospheric pressure.

Further, since the lid member and the case are made of a conductive metal material, the inside of the case is shielded, so that noise due to electromagnetic interference can be reduced. further,
Since the lid member is press-fitted into the case, the lid member and the case can be easily and reliably connected to each other, and the case does not need to be provided with a special structure for holding and conducting the lid member. Thus, the structure can be simplified.

When a connection pin for electrically connecting the pressure sensor and the first connector portion is provided through the lid member in such a case, a penetrating capacitor is inserted through the lid member. The connection pin may be inserted into the through capacitor, which is electrically connected to the lid member.

As described above, if the connection pin is inserted into the feedthrough capacitor grounded to the case via the lid member, noise on the connection pin is effectively cut, and the noise resistance of the pressure transmitter is further improved. it can. In addition, since the feedthrough capacitor is attached to the lid member, the lid member can also be used as the ground line of the feedthrough capacitor, so that an increase in the number of members can be suppressed and the size of the pressure transmitter can be reduced.

In the above, the second connector portion may include an electric wire electrically connected to the first connector portion, and the air passage may be formed by a gap in the electric wire that is continuous in a longitudinal direction. Here, as the electric wire, for example, one having a structure in which a single core wire formed by knitting a thin conductive wire is covered with a sheath, and one in which a plurality of core wires such as lead wires are collectively covered with a sheath can be adopted. In this case, the continuous gap in the longitudinal direction in the electric wire, in the former case, for example, the gap between the core wire and the jacket, or the core wire itself, that is, the gap between the conductors, in the latter case, for example, the core wire And a gap between the outer sheath and the inside of the core wire. In addition, a ventilation pipe through which air can flow may be positively provided inside the electric wire, and this ventilation pipe may be used as a gap in the electric wire, that is, a ventilation path.

As described above, if the ventilation path is formed by utilizing the gap in the electric wire, it is not necessary to separately form a hole for the ventilation path in the second connector portion, so that the ventilation path can be easily formed. In addition, the use of an electric wire can make the ventilation path longer than providing a hole directly in the second connector portion.
The end that is open to the atmosphere is often connected to an electronic device or a power supply that is installed in an environment with little water or mud, so that water or the like does not enter the ventilation path.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a pressure transmitter 5 of the present embodiment. The pressure transmitter 5 connects a wire 66 using a pair of connector portions 62 and 63, and is, for example, a vehicle-mounted pressure transmitter. The pressure transmitter 5 according to the present embodiment includes a detection unit 50 that detects a pressure difference between a detected pressure and an atmospheric pressure and converts the pressure difference into an electric signal.
0, and a first connector portion 62 that is integrated with the case 61 and hermetically seals the case 61.
And a second connector 63 provided so as to be able to be fitted to and detached from the first connector 62, and a joint 70 for connecting the case 61 to the portion to be measured.

The detection unit 50 includes a pressure sensor 51 having a pressure sensing surface 51A for receiving a detected pressure and an atmospheric pressure receiving surface 51B for receiving an atmospheric pressure, and a circuit having a circuit for processing an electric signal from the pressure sensor 51 mounted thereon. And a substrate 52. Although not shown, the pressure sensor 51 has a diaphragm and a converting means for detecting deformation of the diaphragm and converting it to an electric signal, and both surfaces of the diaphragm are respectively a pressure-sensitive surface 51A and an atmospheric pressure receiving surface 51A.
B. The pressure sensor 51 of the present embodiment is a strain gauge type pressure sensor in which a strain gauge is provided on the atmospheric pressure receiving surface 51B of the diaphragm. The pressure sensor is not limited to this strain gauge type pressure sensor.For example, a diaphragm and an electrode are arranged to face each other, and the displacement of the diaphragm is changed by the capacitance of the electrode and the electrode provided on the diaphragm. Another pressure sensor such as a capacitance type pressure sensor that detects a change may be used.

The pressure sensor 51 is held in a resin holder 512 provided with a plurality of claws 512A (only one is shown in FIG. 1) on the peripheral edge. The circuit board 52 is locked to these claw portions 512A, and the circuit board 5
2 is stacked on the pressure sensor 51. Circuit board 5
Reference numeral 2 denotes a substrate in which a flexible substrate 522 is mounted on a substrate 521, and is electrically connected to the pressure sensor 51 by wire bonding or the like. On the circuit board 52, connection pins 524 for electrically connecting the pressure sensor 51 and a later-described first connector portion 62 via the circuit board 52 are provided upright.

The pressure sensor 51 and the circuit board 5
2 is housed in a metal cylindrical case 61.
The case 61 includes a pressure sensor 51 and a circuit board 5.
2 from the first connector portion 62 side
Is press-fitted, and the connection pins 524 of the circuit board 52 are inserted through the lid member 53. The cover member 53 has a connection surface 53A that rises along the case 61 on the peripheral edge thereof. When the cover member 53 is pressed into the case 61, the connection surface 53A
Is pressed against the case 61 so that the lid member 53 is held in the case 61 and is electrically connected to the case 61.

A through capacitor 531 is inserted through the lid member 53, and the outer peripheral surface thereof is electrically connected to the lid member 53 by soldering or the like. The connection pin 524 described above is inserted into the feedthrough capacitor 531 and is electrically connected to the inner peripheral surface thereof. Further, the cover member 53 is formed with a ventilation hole 532 for passing air through the cover member 53.

One end of a metal joint 70 is inserted into the opening of the case 61 on the pressure sensor 51 side, and is fixed to the case 61 and the pressure sensor 51 by welding. Thus, the joint 70 and the case 61 are electrically connected. Further, inside the joint 70, a flow hole 70A for flowing the fluid along the axis is formed, and the fluid can be guided from the measured portion to the pressure-sensitive surface 51A of the pressure sensor 51 through the flow hole 70A. I have.

In this embodiment, the metal joint 70, the case 61 and the cover member 53 are electrically connected to each other and are electrically connected to a ground line (not shown). The pressure sensor 51 and the circuit board 52 are completely covered by the joint 70, the case 61, and the cover member 53, so that noise due to electromagnetic interference can be removed. Further, since the outer peripheral surface of the feedthrough capacitor 531 is electrically connected to the case 61 via the lid member 53, the outer peripheral surface is electrically connected to the ground line, so that noise on the connection pin 524 can be removed.

On the other hand, the first connector portion 62 is fitted and caulked into the opening of the case 61 on the side of the lid member 53, and is integrated with the case 61. A resin mold 54 for preventing air leakage is applied between the first connector portion 62 and the lid member 53 along the inner peripheral surface of the case 61.
The airtightness and watertightness within 1 are ensured. The first connector portion 62 is a male connector, and includes a contact 621 connected to the circuit board 52 via the flexible board 55 and the connection pins 524.

The first connector portion 62 has a space between the first connector portion 62 and the second connector portion 63,
A through hole 64 communicating with the internal space of the case 61 is provided. The case-side opening 64A of the through hole 64 is covered and closed by a filter 65 having air permeability and waterproofness. The filter 65 has both air permeability that allows air to pass and waterproofness that does not allow moisture to pass, and is made of, for example, a porous fluororesin-based material. The filter 65 is provided with a connection portion 65A made of metal, resin, or the like on a peripheral portion thereof.
Is ultrasonically welded to the open end of the case-side opening 64A.

The second connector portion 63 is provided with an electric wire 6 electrically connected to the contact 621 of the first connector portion 62 by fitting the first and second connector portions 62 and 63 together.
6 is provided. The electric wire 66 has a continuous gap in the longitudinal direction inside thereof, and the gap forms a ventilation path 67 communicating from the space between the first connector section 62 and the second connector section 63 to the atmosphere. This electric wire 66
Is, for example, an electric wire having a structure in which a single core wire formed by knitting a thin conductive wire is covered with a jacket, and a continuous gap in the wire in the longitudinal direction is a gap between the core wire and the jacket, or the core wire itself. This is the gap between the conductors. The structure and type of the electric wire 66 are not particularly limited as long as the electric wire 66 has a gap that is continuous in the longitudinal direction, and the electric wire 66 is used for signal transmission, for power supply, and for performing both signal transmission and power supply. Any electric wire can be adopted.

When installing the pressure transmitter 5 configured as described above, the second connector section 63 is detached from the first connector section 62 and separated, and the case 61 and the second After attaching one connector part 62 to the part to be measured, the second connector part 63 is fitted to the first connector part 62, and the electric wire 66 is connected to the contact 621 of the first connector part 62.

In the pressure transmitter 5 of the present embodiment, when the pressure inside the case 61 becomes lower than the outside air, the air outside the pressure transmitter 5 is opposite to the second connector 63 side of the electric wire 66. From the end on the side through the internal gap into the space between the second connector portion 63 and the first connector portion 62, and from the through hole 64 of the first connector portion 62 to the filter 6.
5 is led to the internal space of the case 61. In the filter 65, moisture, dust, and the like are removed, and only the atmosphere passes. Therefore, dust, water, and the like do not enter the inside of the case 61 together with the atmosphere. The air introduced into the case 61 flows into the pressure sensor 51 through the ventilation hole 532 of the cover member 53, and the atmospheric pressure receiving surface 51B of the pressure sensor 51.
The pressure in the side space becomes the same pressure as the atmosphere. This allows
Atmospheric pressure of the same pressure as the atmosphere is applied to the atmospheric pressure receiving surface 51B.

Conversely, when the pressure inside the case 61 becomes higher than the atmosphere, the air flows in the opposite direction to the flow of the air and is exhausted from the end of the electric wire 66 to the outside. Thereby, the same atmospheric pressure as the atmosphere outside the pressure transmitter 5 is constantly applied to the atmospheric pressure receiving surface 51B. On the other hand, the fluid of the measured part is introduced into the pressure sensing surface 51A of the pressure sensor 51 through the flow hole 70A of the joint 70, and the pressure sensing surface 51A
A is applied with the pressure of the fluid, that is, the detected pressure.

As described above, the pressure-sensitive surface 51A of the pressure sensor 51
On the other hand, on the atmospheric pressure receiving surface 51B, the diaphragm is displaced due to the difference between the detected pressure and the atmospheric pressure, and the displacement is detected and converted into an electric signal. This electric signal is processed in the circuit board 52 or the like,
The data is sent to an external device such as a display device or a control device via the electric wire 66.

According to this embodiment, the following effects can be obtained. That is, the internal space of the case 61 is
The case 61 is communicated with the atmosphere through the through hole 64 of the first connector portion 62, the space between the first and second connector portions 62 and 63, and the air passage 67 of the second connector portion 63.
Internal and external ventilation can be secured. Of these, the first connector 6
Since the second through-hole 64 is sealed by the filter 65 having air permeability and waterproofness, the first connector 6
Even when the through-hole 64 is exposed in a state where the second connector portion 63 is detached from the second connector 2, the filter 65 can prevent water, dust and the like from entering the case 61, and
Since only air excluding water, dust, dust and the like can be introduced into the case 61, excellent waterproof and dustproof properties can be obtained, and components in the case 61 including the pressure sensor 51 can be reliably protected.

Since the filter 65 is provided so as to seal the case-side opening 64A of the through hole 64, the entire filter 65 is not exposed to the outside. Because it is protected, trash, mud, pebbles, etc. will collide with the filter 65,
Adhesion can be prevented. Further, even if the first and second connector portions 62 and 63 are separated from each other and placed in an environment exposed to a strong wind or the like, it is less likely to be directly hit by the strong wind or the like. Therefore, even when the measurement environment is severe, it is possible to prevent the filter 65 from being clogged due to the attachment of dust and the like, to continuously maintain the air permeability, and to prevent the filter 65 from being damaged by dust and strong wind. Can maintain waterproofness.

The connecting portion 65A of the filter 65 is
Since the ultrasonic welding is performed on the opening end of the case-side opening 64A, the filter 65 can be securely brought into close contact with the case-side opening 64A without any gap in a short time.

Further, the case 61 includes a pressure sensor 51.
Is provided from the first connector portion 62 side, so that the pressure sensor 51 and the first connector portion 62 are shut off. Therefore, even if dust, dust, water, or the like enters through the through hole 64, , Can be prevented from entering the pressure sensor 51 side. Since air holes 532 are formed in the lid member 53, air can flow between the pressure sensor 51 and the first connector portion 62 through the air holes 532. The received pressure can be reliably made equal to the atmospheric pressure.

Then, the lid member 53 and the case 61
Since the case 61 is made of a conductive metal material, the inside of the case 61 is shielded, so that noise due to electromagnetic interference can be reduced. Further, since the lid member 53 is press-fitted into the case 61, the lid member 53 and the case 61 can be easily and reliably connected to each other.
Since there is no need to provide a special structure for holding and conducting the 3, the structure can be simplified.

Further, a penetrating capacitor 531 that is electrically connected to the case 61 through the lid member 53 is inserted through the lid member 53, and a connection pin 524 is inserted into the penetrating capacitor 531.
, The noise on the connection pin 524 can be effectively cut, so that the noise resistance of the pressure transmitter 5 can be further improved. Further, the feedthrough capacitor 531
Is attached to the lid member 53,
Can also be used as the ground line of the feedthrough capacitor 531, so that an increase in the number of members can be suppressed and the size of the pressure transmitter 5 can be reduced.

Since the air passage 67 is formed by using the gap in the electric wire 66, it is not necessary to separately form a hole for the air passage in the second connector portion 63. Can be configured. In addition, when the electric wire 66 is used, the ventilation path 67 can be made longer than when a hole is directly provided in the second connector portion 63, and the end of the electric wire 66 that is open to the atmosphere has little water or mud. Since it is often connected to an electronic device or a power supply installed in the environment, water or the like does not enter the ventilation path 67.

It should be noted that the present invention is not limited to the above-described embodiment, but includes other configurations that can achieve the object of the present invention, and the following modifications are also included in the present invention.

In the above embodiment, the filter 65 is mounted so as to cover the case-side opening 64A of the through hole 64.
As shown in FIG. 2, the filter 68 may be press-fitted into the through hole 64, and the surrounding connection portion 68A may be fixed by ultrasonic welding, an adhesive or the like. Further, the filter may be joined by a method other than ultrasonic welding, for example, may be fixed with only an adhesive, or may be fixed by caulking to an opening on the case side.

In the above-described embodiment, the air passage 67 of the second connector portion 63 is formed by a gap in the electric wire 66.
As shown by a two-dot chain line, a hole 631 communicating with the atmosphere may be provided in the second connector portion 63, and the hole 631 may be used as the ventilation path 69.

Further, the fitting structure of the first and second connector parts is not particularly limited. Contrary to the above embodiment, the first connector part may be a female connector and the second connector part may be a male connector. .

[0044]

As described above, according to the present invention,
A pressure sensor, a case in which the pressure sensor is housed,
In a pressure transmitter including a first connector unit integrated with the case and a second connector unit provided so as to be able to be fitted to and detached from the first connector unit, the internal space of the case is the first space. Since it communicates with the atmosphere through the through hole of the connector part, the space between the first and second connector parts, and the ventilation path of the second connector, ventilation inside and outside the case is ensured.

Since the through-hole of the first connector is sealed by a filter having air permeability and waterproofness, the through-hole is exposed when the second connector is detached from the first connector. Even so, since the filter can prevent water, dust and the like from entering the case, excellent waterproof and dustproof properties can be obtained. Further, since the filter has air permeability, only air excluding water, dust, dust and the like can be introduced into the case, so that components in the case including the pressure sensor can be reliably protected. And since the filter is provided so as to seal the case-side opening of the through hole, the entire filter is not exposed to the outside,
Since it is protected by the case and the first connector portion, it is possible to prevent dust, mud, pebbles and the like from colliding with and attaching to the filter. Therefore, even when the measurement environment is severe, it is possible to prevent the filter from being clogged due to the attachment of dust and the like, to continuously maintain the air permeability, and to prevent the filter from being damaged by pebbles, etc., thereby maintaining the waterproofness of the filter. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing another pressure transmitter of the present invention.

[Explanation of symbols]

 5 Pressure Transmitter 51A Pressure Sensing Surface 51B Atmospheric Pressure Receiving Surface 51 Pressure Sensor 53 Cover Member 61 Case 62 First Connector 63 Second Connector 64 Through Hole 64A Case Side Opening 67,69 Vent 65,68 Filter 65A, 68A Connection Part 66 Electric wire 524 Connection pin 531 Through capacitor 532 Vent hole

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takayuki Yokoyama Nagano Keiki Co., Ltd. 1-30-4 Higashimagome, Ota-ku, Tokyo

Claims (5)

[Claims] 1. A pressure sensor having a pressure-sensitive surface for receiving a detected pressure of a portion to be measured and an atmospheric pressure receiving surface for receiving an atmospheric pressure, and detecting a pressure difference between the detected pressure and the atmospheric pressure and converting it into an electric signal. A case in which the pressure sensor is housed, a first connector unit integrated with the case to hermetically seal the case, and a second connector unit provided so as to be able to be fitted to and removed from the first connector unit. Wherein the first connector portion is provided with a through hole that communicates a space between the first connector portion and the second connector portion and an internal space of the case, The second connector portion is provided with an air passage that communicates with the atmosphere from the space between the first connector portion and the second connector portion, and the case-side opening of the through hole is formed by a filter having air permeability and waterproofness. Sealed Pressure transmitter. 2. The pressure transmitter according to claim 1, wherein the filter includes a connection portion at a peripheral portion thereof, and the connection portion is ultrasonically welded to an opening end of the case-side opening. Characterized pressure transmitter. 3. The pressure transmitter according to claim 1, wherein a lid member that covers the pressure sensor from the first connector side is press-fitted into the case, A pressure transmitter, wherein pores are formed, and the lid member and the case are made of metal. 4. The pressure transmitter according to claim 3, wherein a connection pin for electrically connecting the pressure sensor and the first connector portion is provided through the lid member in the case. A pressure transmitter, wherein a penetrating capacitor is inserted through the lid member and is electrically connected to the lid member, and the connection pin is inserted through the penetrating capacitor. 5. The pressure transmitter according to claim 1, wherein the second connector section includes an electric wire electrically connected to the first connector section, and the ventilation path. Is a pressure transmitter constituted by a gap continuous in the longitudinal direction in the electric wire.