JP2000121470A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure sensor which makes it possible to form an atmospheric pressure leading-in element by a simple construction without forming a special hole in a housing, makes it possible to prevent water and dust from entering directly, and besides makes it possible to lead an atmospheric pressure into the housing surely. SOLUTION: This is a pressure sensor which has a sensor element arranged in a state of receiving the pressure of a medium to be measured to be led in from a pressure leading-in hole, a housing 11 which houses the sensor element, and an electric cord 9 for supplying an electric signal outputted from the sensor element to the outside, and a hose 22 which is drawn outside from the housing 11 along with the electric cord 9 and connects the inside of the housing 11 to the outside of the housing 11 is provided, and a protective pipe 23 for protecting the electric cord 9 is provided outside the housing 11, and the end section of the hose 22 is positioned inside the protective pipe 23 and provided as an opening 22A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor for detecting the pressure of a medium to be measured.

[0002]

2. Description of the Related Art A pressure sensor for detecting the pressure of a medium to be measured, such as a liquid or a gas, particularly a so-called relative pressure detecting type sensor for measuring the pressure difference between the atmospheric pressure and the medium to be measured, It is necessary to provide an atmospheric pressure introducing portion for introducing atmospheric pressure to a predetermined location of the housing for housing the sensor element to make the outside of the housing and the inside of the housing have the same pressure, and generally a part of the housing. Are provided as holes. In this case, in order to prevent intrusion of moisture, dust, etc., the position of the hole for introducing atmospheric pressure is set in consideration of the installation state of the pressure sensor, or moisture or dust is directly introduced from the hole for introducing atmospheric pressure. For example, a maze-like structure or a filter is provided to prevent intrusion of dust or the like. In other words, in the case of providing a hole in the housing as described above, in order to prevent moisture and dust from entering the inside of the housing from the hole, the position of the hole is considered, It is necessary to perform some processing, which has become a factor of complicating the structure.

[0003] As a structure of an atmospheric pressure introducing portion in a pressure sensor that has already been proposed to improve this point, for example, Japanese Patent No. 2568963 discloses an electric cord for supplying a signal from a sensor element to the outside. It has been shown to introduce atmospheric pressure via. That is, there is disclosed an apparatus in which a slight gap between an insulating tube constituting an electric cord and a stranded wire located in the insulating tube is used as an atmospheric pressure introducing section to introduce atmospheric pressure.

[0004]

In the above-described atmospheric pressure introducing structure of the conventional pressure sensor, the existing parts can be used as the atmospheric pressure introducing portion by using the electric cord as the atmospheric pressure introducing portion. Although there is no need to provide special holes, it is effective in preventing the intrusion of moisture and dust, but the use of the small gap between the insulating tube and the stranded wire that make up the electric cord makes it very large. It takes a considerable amount of time to completely introduce atmospheric pressure to the inside of the housing, and the introduction of atmospheric pressure becomes uncertain, and accurate pressure detection may not be performed. You can say that.

According to the present invention, it is possible to form an atmospheric pressure introducing portion with a simple structure without providing a special hole in a housing, to prevent direct entry of moisture and dust, and to introduce atmospheric pressure into the housing. It is an object of the present invention to provide a pressure sensor capable of reliably performing the pressure sensor.

[0006]

According to the present invention, there is provided a sensor element disposed under a pressure of a medium to be measured introduced from a pressure introducing hole, a housing for accommodating the sensor element, and a sensor element. A pressure sensor having an electric cord that supplies an electric signal to be output to the outside, wherein a hose that is drawn out of the housing together with the electric cord and communicates the inside of the housing and the outside of the housing is provided, A protection tube for protecting the electric cord is provided outside the housing, and an end of the hose is provided as an opening positioned inside the protection tube.

Further, the housing has a drawer for drawing out the electric cord and the hose, and a filler is provided in the drawer.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a pressure sensor according to the present invention, a pressure is converted into an electric signal by a sensor element arranged in a state of receiving a pressure of a medium to be measured introduced from a pressure introducing hole, and the electric signal is converted to an external signal. A pressure sensor adapted to be supplied by using an electric cord, having a housing for accommodating the sensor element, being drawn out of the housing together with the electric cord, and communicating with the inside of the housing and the outside of the housing. And a protective tube for protecting the electric cord outside of the housing, and an opening is provided in which an end of the hose is located inside the protective tube. In this way, the atmospheric pressure can be reliably introduced into the housing by the hose, the atmospheric pressure and the interior of the housing can be made equal, and accurate pressure detection can be performed. At this time, since the end of the hose is open to the atmosphere in a protective tube for protecting the electric cord, it is possible to prevent moisture, dust and the like from entering the end of the hose by the protective tube.

The hose is drawn out from the inside of the housing to the outside of the housing together with the electric cord through a drawer of the housing, and is sealed and fixed by the filler together with the electric cord at the drawer. ,
The electric cords are bundled similarly to the electric cords drawn out from the same drawer, and can be held together by the protective tube. Since the base portion of the electric cord and the hose with respect to the housing is sealed with the filler, it is possible to prevent moisture, dust and the like from entering from the base portion.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 3 show one embodiment of the present invention. The pressure sensor according to the present embodiment detects the pressure of a medium to be measured such as water, oil or gas, and is formed by insert-molding a metal pressure introducing cylinder 2 having a mounting screw portion 1 at a lower portion. A lower housing 3 made of resin, a base plate 4 disposed at an upper end of the pressure introducing cylinder 2, a semiconductor sensor element 5 disposed on the base plate 4 under pressure, and a sensor element 5. Printed circuit board 6 electrically connected to the circuit board, and amplifying circuit section 7 mounted on printed circuit board 6
A terminal 8 provided at an end of the printed circuit board 6 for supplying an output signal to the outside, an electric cord 9 connected to the terminal 8, and a drawer 10 supporting the electric cord 9, made of synthetic resin. And the upper housing 11.

The lower housing 3 is made of a heat-resistant and creep-resistant synthetic resin material, for example, polyphenylene sulfide (PPS), and the metal pressure introducing cylinder 2 is integrally insert-molded and the sensor element 5 is housed therein. It is a function to perform. The pressure introducing cylinder 2 insert-molded in the lower housing 3 is opened at the inlet side, and the pressure of the medium to be measured is transmitted through the pressure introducing hole 12 to the sensor element 5.
Serve to communicate to A screw portion 1 made of a synthetic resin is formed integrally with the lower housing 3 at a lower portion of the lower housing 3, and the screw portion 1 is screwed and fixed to a measuring portion composed of, for example, a vehicle engine.

The pressure introducing cylinder 2 is formed in a tubular shape by a metal material made of, for example, stainless steel. One end of the pressure introducing hole 12 is opened to serve as an inlet for introducing pressure, and the other end is provided with a base. Placement part 13 for disposing plate 4
Is provided.

The base plate 4 is made of a substantially circular member and made of a metal material such as Kovar having a thermal expansion coefficient close to the thermal expansion coefficient of the sensor element 5. Flange section 1 for disposing on mounting section 13
4, a projection 15 which fits into the pressure introducing hole 12 of the pressure introducing cylinder 2, and which determines the disposition position of the base plate 4 with respect to the pressure introducing cylinder 2, and a sensor element which communicates with the pressure introducing hole 12. 5 is formed with a hole 16 for transmitting pressure.

The base plate 4 is a flange 1 of the base plate 4.
4 is welded to the mounting portion 13 of the pressure introducing cylinder 2 so that the pressure introducing cylinder 2 is hermetically disposed on the pressure introducing cylinder 2. The base plate 4 is interposed between the sensor element 5 and the pressure introducing cylinder 2 and serves as an intermediate member for absorbing a difference in deformation due to a difference in thermal expansion coefficient between the two.

The sensor element 5 converts the pressure of the medium to be measured into an electric signal. The sensor element 5 is air-tight by anodic bonding of a thin diaphragm having a semiconductor strain gauge formed on a glass pedestal. The glass pedestal is formed with a hole 17 for transmitting the pressure to the diaphragm. Also,
The sensor element 5 has a metallized layer formed on a surface facing the glass pedestal and the base plate 4.
6 and the hole 17 of the sensor element 5 are combined so as to communicate with each other and soldered onto the base plate 4 to be mounted in an airtight manner.

The printed board 6 is electrically connected to the sensor element 4 by wire bonding.
It is formed by FPC (Flexible Printed Circuit). A printed circuit board 6 made of the FPC includes a sensor connection portion 18 that is wire-bonded to the sensor element 5, an amplification circuit section 7 that amplifies an electric signal from the sensor element 5 and performs a predetermined noise removal process, and an amplification circuit. All the terminals 8 for connecting to an electric cord 9 for supplying the electric signal amplified by the unit 7 to the outside are provided on one printed circuit board 6. This printed circuit board 6
Is made of an FPC, is bent at a predetermined location, and is housed in a housing constituted by the lower housing 3 and the upper housing 11.

The amplifier circuit section 7 is provided as an IC package having a function of removing external noise by the amplifier circuit section 7, a temperature compensation function, a voltage range adjustment function, and the like. There is no need to provide this, and the electrical connection can be simplified. The amplifying circuit section 7 made of this IC package is provided between the sensor connection section 18 and the terminal 8, and the printed circuit board 6 made of FPC is provided. The reinforcing plate 19 is attached to one surface, and the amplifier circuit 7 is surface-mounted on the other surface, and is electrically connected to the printed circuit board 6 by soldering. The amplification circuit section 7 includes a reinforcing plate 19 and a holder 20.
And is fixed on the lower housing 3.

The terminal 8 is provided at an end of the printed circuit board 6 and is connected by soldering to a cord 9 for supplying a signal detected by the sensor element 5 and amplified by the amplifier circuit section 7 to the outside. .

The electric cord 9 is combined with the lower housing 3 by a drawer 10 of the upper housing 11 which houses the sensor element 5, the printed circuit board 6, and the amplifier circuit section 7.
It is guided and supported via the grommet 21 and is led out of the upper housing 11.

In the present invention, the electric cord 9 is used.
Further, a hose 22 is provided which is drawn out of the drawer 10 of the upper housing 11 and communicates the inside of the upper housing 11 and the outside of the upper housing 11.

The hose 22 is formed of a hollow flexible member, is supported by the upper housing 11 via the grommet 21 together with the electric cord 9, and is bundled together with the electric cord 9 outside the upper housing 11. It is inserted through a protective tube 23 to be protected.

The protective tube 23 is made of a hollow flexible member, and accommodates the electric cord 9 and the hose 22 therein, and the electric cord 9 and the hose 22 are rubbed with other members when the pressure sensor is mounted. It is provided for the purpose of preventing damage and preventing the covering of the electric cord 9 and the melting and deterioration of the hose 22 due to contact with other members that become hot. The electric cord 9 and the hose 22 are bundled and accommodated. Possible inner diameter is secured.

In this case, the aforementioned hose 22 is
With one end located in the upper housing 11,
The other end located outside the upper housing 11 is connected to the protective tube 2.
3 are provided as openings 22A.
By doing so, the atmospheric pressure can be reliably introduced into the housing by the hose 22, and the same pressure can be applied between the atmosphere and the inside of the housing. At this time, the end of the hose 22 is opened to the atmosphere in the protective tube 23 by the opening 22A of the hose 22 located in the protective tube 23 for protecting the electric cord 9. 23 prevents moisture, dust, and the like from entering the opening 22A of the hose 22, and at the same time prevents moisture, dust, and the like from entering the housing. In this case, since the atmosphere is introduced from the inside of the protective tube 23 for protecting the electric cord 9 by the hollow hose 22, for example, the inside of the conventional electric cord (the gap between the insulating tube and the stranded wire is used. The air can be reliably introduced into a wider space as compared with the ventilation described in (1), and accurate pressure detection can be performed.

The upper housing 11 is formed of a resin material made of, for example, polybutylene terephthalate (PBT). A concave portion 24 is formed in an upper portion. The cord 9 and the hose 22 are formed from the inside of the upper housing 11 toward the concave portion 24. The recess 24 is drawn out.
The filler 9 made of epoxy resin flows in from the upper part of the grommet 21 disposed in the
In addition, the hose 22 is fixedly supported and prevents dust and moisture from entering the upper housing 11 from the cord 9 and the base of the hose 22.

By doing so, the hose 22 is connected to the upper housing 1 via the drawer 10 in the same manner as the electric cord 9.
1 is drawn out from the inside, and the lead-out portion 10 is sealed with a filler 25, so that intrusion of moisture, dust, and the like from the lead-out portion 10 is prevented, and the lead-out portion 10 is put together with the electric cord 9 by the protective tube 23. There is also an effect that can be done.

After being assembled with the lower housing 3, the upper housing 11 is fixed to the lower housing 3 by heat caulking so that the entire lower end of the upper housing 11 is bent inward.

Further, a drawer is provided on the lower housing side without providing the upper housing 11 as shown in the above-described embodiment, and a simple cover member having no drawer is provided as the upper housing. The pressure sensor may be configured by caulking and fixing in combination with the housing.

The length of the hose 22 extending from the inlet of the protection tube 23 to the inside position is set to such a length that air can be introduced into the housing, and the protection tube 23 covers the end 22A of the hose 22. The length may be appropriately set so that moisture or dust cannot directly enter.

[0029]

As described above, according to the present invention, the atmospheric pressure introducing portion can be formed by a simple structure without providing a special hole in the housing, and it is possible to prevent moisture and dust from directly entering the housing and to enter the inside of the housing. Pressure sensor that can reliably introduce atmospheric pressure.

[Brief description of the drawings]

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

FIG. 2 is an external view showing an embodiment of the present invention.

FIG. 3 is a sectional view of a main part showing one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 3 Lower housing 5 Sensor element 9 Electric cord 10 Leader 11 Upper housing 12 Pressure introducing hole 22 Hose 22A Opening 23 Protective tube 25 Filler

Claims (2)

[Claims] 1. A sensor element disposed under a pressure of a medium to be measured introduced from a pressure introducing hole, a housing for accommodating the sensor element, and an electric signal output from the sensor element to the outside. A pressure sensor having an electric cord to be supplied, wherein a hose is drawn out of the housing together with the electric cord and communicates with the inside of the housing and the outside of the housing, and the electric cord is provided outside the housing. A pressure sensor, wherein a protective tube for protection is provided, and an end of the hose is provided as an opening positioned inside the protective tube. 2. The pressure sensor according to claim 1, wherein a drawer for drawing out the electric cord and the hose is provided in the housing, and a filler is provided in the drawer.