JP2010197119A - Liquid level detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid level detector capable of detecting a quantity of liquid in a tank in a superior manner, even when the tank is a small fuel tank. <P>SOLUTION: The liquid level detector includes a pair of plate members 1, 2 at least one of which has openings 1a, 2a; a spacer member 3, disposed so as to form a housing space between the plate members 1, 2; thin-film members 4, 5 which are disposed so as to face the openings 1a, 2a, and receive the pressure of the liquid varying along with the liquid level from the openings 1a, 2a; and a pressure sensor 8 which is disposed in the housing space so as to face the thin-film members 4, 5, and detects the displacements of the thin-film members 4, 5 accompanying the variations in the pressure of the liquid. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid level detection device that detects the amount of liquid stored in a tank.

  Conventionally, as a liquid level detection device that detects the amount of liquid such as fuel in a fuel tank of a vehicle, for example, a float that follows up and down according to the liquid level, a float arm that includes this float at one end, A housing that rotatably supports the other end of the float arm, a permanent magnet that is provided in the housing and rotates in conjunction with the movement of the float arm, and an electrical resistance value is obtained by the rotation of the permanent magnet. A liquid level detection device provided with a changing semiconductor sensor has been proposed (see, for example, Patent Document 1).

JP-A-8-94413

  By the way, especially the fuel tank in a vehicle has been in the trend of miniaturization in recent years, and if the shape becomes more complicated, the operating range of the float may become insufficient and the liquid level may not be detected by the float. There was room for further improvement as a device.

  Accordingly, the present invention has been made in view of the above points, and an object of the present invention is to provide a liquid level detection device that can satisfactorily detect the amount of liquid in a small fuel tank.

  In the present invention, in order to solve the above problems, at least one of the pair of plate members having an opening, a spacer member disposed so as to form a storage space between the plate members, and the opening A thin film member that is disposed so as to face the liquid and receives a pressure of a liquid that changes in conjunction with a liquid level from the opening, and is disposed so as to face the thin film member in the storage space, And a pressure sensor for detecting a displacement of the thin film member accompanying a change in pressure.

  Further, the thin film member is sandwiched between the plate member and the spacer member.

  In addition, a transmission member is provided between the thin film member and the pressure sensor, and transmits a displacement of the thin film member to the pressure sensor.

  The opening is formed so as to face at least the pressure sensor.

  The opening is formed in a plurality so as to surround the pressure sensor.

  In addition, the spacer member includes an introduction portion for introducing an external atmospheric pressure into the storage space from an introduction pipe communicating with the outside.

  Further, a wiring member electrically connected to the pressure sensor is inserted into the introduction pipe.

  The first and second plate-like members are formed in a disc shape.

  The pressure sensor is a semiconductor pressure sensor.

  The liquid level detection device of the present invention can satisfactorily detect the liquid level in the tank even in a small fuel tank.

The perspective view which shows the liquid level detection apparatus which is embodiment of this invention. Sectional drawing which shows a liquid level detection apparatus same as the above.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  As shown in FIGS. 1 and 2, the liquid level detection device includes a first plate member 1, a second plate member 2, a spacer member 3, a first thin film member 4, and a second plate member 2. It is mainly composed of a thin film member 5, a first metal plate (transmission member) 6, a second metal plate (transmission member) 7, a pressure sensor 8, an introduction tube 9, and a wiring member 10. Is. The liquid level detection device is disposed, for example, in a fuel tank of a vehicle, and detects the amount of liquid (fuel) in the tank.

  The first and second plate-like members 1 and 2 are made of, for example, a metal material such as SUS in a disc shape, and are opposed to each other with a predetermined interval. The first and second plate-like members 1 and 2 have a plurality of openings 1a and 2a, respectively. The openings 1a and 2a are formed one by one in the approximate center of the first and second plate-like members 1 and 2 so as to face the pressure sensor 8, and further on the same circumference so as to surround the pressure sensor 8. A plurality are formed.

  The spacer member 3 is made of, for example, a metal material such as SUS, and is formed in a ring shape so as to form a storage space for storing each member such as the pressure sensor 8 between the first and second plate-like members 1 and 2. And a flange portion 3b extending from the spacer portion 3a. The first and second plate members 1 and 2 and the spacer member 3 are fixed by means such as screws. An insertion hole 3c into which the introduction tube 9 is inserted is formed in the flange portion 3b. In addition, the spacer member 3 is formed with an introduction hole (introduction portion) 3 d for introducing the atmospheric pressure in the tank, which is the outside, from the introduction pipe 9 to the storage space and leading the wiring member 10 into the introduction pipe 9. .

  The first thin film member 4 is formed by forming a flexible resin material such as polyimide in a disc shape, and is sandwiched between the first plate member 1 and the spacer member 3. It arrange | positions so that 1 opening part 1a may be opposed. The first thin film member 4 receives the pressure of the liquid that changes in conjunction with the liquid level of the liquid from the opening 1a and is displaced. Specifically, when the pressure of the liquid is received, bending occurs in the pressure sensor 8 side direction.

  The second thin film member 5 is formed by forming a resin material such as polyimide into a disk shape, and is sandwiched between the second plate member 2 and the spacer member 3, and the opening of the second plate member 2. It is arrange | positioned so that 2a may be opposed. The second thin film member 5 receives the pressure of the liquid that changes in conjunction with the liquid level of the liquid from the opening 2a and is displaced. Specifically, when the pressure of the liquid is received, bending occurs in the pressure sensor 8 side direction.

  The first metal plate 6 is formed, for example, by forming a metal material such as SUS into a disc shape, and is disposed in the storage space so as to be positioned between the first thin film member 4 and the pressure sensor 8. Is. The first metal plate 6 is disposed such that one surface (upper surface in FIG. 2) is in contact with the first thin film member 4 and the other surface (lower surface in FIG. 2) is in contact with the detection portion 8a of the pressure sensor 8. Has been.

  The second metal plate 7 is formed, for example, by forming a metal material such as SUS into a disc shape, and is disposed so as to be positioned between the second thin film member 5 and the pressure sensor 8 in the storage space. Is. The second metal plate 7 is disposed so that one surface (the lower surface in FIG. 2) is in contact with the second thin film member 5, and the pressure sensor 8 is mounted on the other surface (the upper surface in FIG. 2). It is mounted via.

  As the pressure sensor 8, for example, a semiconductor pressure sensor capable of detecting a minute displacement is used, and the pressure received from the detection unit 8a is converted into an electric signal using a strain (strain) gauge. The pressure sensor 8 is disposed in the storage space so as to face the first and second thin film members 4, 5, and the first and second thin film members 4, 5 according to the change in the pressure of the liquid. Detect displacement. In the present embodiment, the pressure sensor 8 is placed on a pedestal 8 b disposed on the second metal plate 7.

  The introduction tube 9 is made of a metal material such as SUS, and one end thereof is inserted into the insertion hole 3 c of the spacer member 3. The other end of the introduction pipe 9 communicates with the inside of the tank, and introduces the atmospheric pressure in the tank into the storage space through the introduction hole 3d. Further, the wiring member 10 is inserted into the introduction tube 9 through the introduction hole 3d.

  The wiring member 10 is composed of a conductor having good conductivity such as copper and an insulating film covering the conductor, and is electrically connected to the pressure sensor 8, energizing the pressure sensor 8, and an electric signal from the pressure sensor 8. Is output to the outside. The wiring member 10 is drawn out of the tank through the introduction hole 3d and the introduction pipe 9.

  Next, the detection of the liquid level of the liquid level detection device of the present embodiment will be described.

  The first and second thin film members 4 and 5 receive the pressure of the liquid interlocked with the liquid level in the tank via the openings 1a and 2a, respectively, and are displaced (pressure) (Flexion toward the sensor 8 side direction). The displacement of the first thin film member 4 is transmitted to the pressure sensor 8 when the first metal plate 6 applies pressure to the detection portion 8 a of the pressure sensor 8 according to the displacement of the first thin film member 4. Moreover, about the displacement of the 2nd thin film member 5, the 2nd metal plate 7 presses the pressure sensor 8 against the 1st metal plate 6 according to the displacement of the 2nd thin film member 5, and a pressure is applied to the detection part 8a. Is transmitted to the pressure sensor 8. That is, the pressure sensor 8 detects the displacement of the first and second thin film members 4 and 5 together. The pressure sensor 8 outputs a detection signal corresponding to the displacement of the first and second thin film members 4 and 5 to an external device (not shown), and the amount of liquid in the tank is detected.

  In the present embodiment, as a structure for detecting the amount of liquid in the tank, the displacement of the thin film members 4 and 5 receiving the pressure of the liquid from the openings 1a and 2a formed in the pair of plate-like members 1 and 2 is pressure-controlled. By adopting a structure for detecting by the sensor 8, it is not necessary to use a float as in the prior art, so that the liquid level detecting device can be miniaturized, and even in the tank having a small and complicated shape, It becomes possible to detect the liquid amount satisfactorily. In addition, the structure which forms the opening part in only one of the 1st, 2nd plate-shaped members 1 and 2 by using the thin film members 4 and 5 may be sufficient. However, the openings 1 a and 2 a are formed in both the first and second plate-like members 1 and 2, and the two thin film members 4 and 5 are disposed in the vertical direction of the pressure sensor 8. A change in the pressure of the liquid can be sensed from above and below, and even when the change in the pressure of the liquid is small, the amount of liquid in the tank can be detected satisfactorily.

  In addition, first and second metal plates 6 and 7 are disposed between the first and second thin film members 4 and 5 and the pressure sensor 8, respectively. By transmitting the displacement of the first and second thin film members 4 and 5 to the pressure sensor 8, the displacement of the first and second thin film members 4 and 5 made of a flexible material is good with the pressure sensor 8. Can be detected.

  Further, by forming the openings 1a and 2a so as to face the pressure sensor 8, the first and second thin film members 4 and 5 are displaced near the pressure sensor 8, and the first, The displacement of the second thin film members 4 and 5 can be accurately detected by the pressure sensor 8. Further, by forming a plurality of openings 1a and 2a so as to surround the pressure sensor 8, it is possible to increase the displacement amount of the first and second thin film members 4 and 5 and further increase the detection accuracy. .

  The spacer member 3 is formed with an introduction hole 3d for introducing the air pressure in the tank into the storage space from the introduction pipe 9 communicating with the inside of the tank, so that the air pressure in the storage space is equal to the external air pressure. As a result, the displacement of the thin film members 4 and 5 can be detected well. Further, by inserting a wiring member 10 electrically connected to the pressure sensor 8 into the introduction pipe 9, the liquid is prevented from entering and the detection signal of the pressure sensor 8 is reliably transmitted outside the tank. Is possible.

  The present invention is applicable to a liquid level detection device that detects the amounts of various liquids in a tank.

DESCRIPTION OF SYMBOLS 1 1st plate-shaped member 2 2nd plate-shaped member 3 Spacer member 4 1st thin film member 5 2nd thin film member 6 1st metal plate (transmission member)
7 Second metal plate (transmission member)
8 Pressure sensor 9 Introduction pipe 10 Wiring member

Claims (9)

A pair of plate-like members at least one of which has an opening;
A spacer member disposed so as to form a storage space between the plate-like members;
A thin film member that is disposed so as to face the opening and receives a pressure of a liquid that changes in conjunction with a liquid level from the opening; and
A liquid level detecting device, comprising: a pressure sensor disposed in the storage space so as to face the thin film member, and detecting a displacement of the thin film member accompanying a change in pressure of the liquid. . The liquid level detection device according to claim 1, wherein the thin film member is sandwiched between the plate-like member and the spacer member. The liquid level detection device according to claim 1, further comprising a transmission member that is disposed between the thin film member and the pressure sensor and transmits a displacement of the thin film member to the pressure sensor. The liquid level detection device according to claim 1, wherein the opening is formed so as to face at least the pressure sensor. The liquid level detection device according to claim 4, wherein a plurality of the openings are formed so as to surround the pressure sensor. The liquid level detection device according to claim 1, wherein the spacer member includes an introduction portion that introduces an external atmospheric pressure into the storage space from an introduction pipe communicating with the outside. The liquid level detection device according to claim 6, wherein a wiring member electrically connected to the pressure sensor is inserted into the introduction pipe. The liquid level detection device according to claim 1, wherein the first and second plate-like members are formed in a disc shape. The liquid level detection device according to claim 1, wherein the pressure sensor is a semiconductor pressure sensor.

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