JP2007003269A - Liquid level detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid level detector allowing high detection precision by raising/lowering a liquid level in a case suddenly in accordance with a sudden rise/drop in a liquid level when the container is refueled and by reducing fluctuations in the liquid level in the case when the liquid level fluctuates caused by a temporary tilting of the container. <P>SOLUTION: The liquid level detector comprises the container containing liquid, a float 4 for liquid level detection, the case 3 including the float 4, and a liquid communication hole 3f allowing communication between the inside of the case 3 and the container containing the liquid. A variable means 1 is provided which changes the flow channel area of the liquid communication hole 3f. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid level detection device.

  Conventionally, as a device for detecting the amount of liquid in a fuel tank of an automobile, as shown in FIG. 10, a cylindrical case 101 is fixed in a container 100 containing fuel or the like from the bottom of the container 100 to the upper wall. A float 102 is provided in the case 101 so as to be movable up and down, and further includes a guide shaft 103 that penetrates the center of the float 102 and is arranged so that the float 102 can be raised and lowered. A liquid level detection device that detects a liquid level by raising and lowering the float 102 using a reed switch 104 provided in the shaft 103 and a magnet 105 embedded in the float 102 is known. A communication hole 101a for introducing the liquid in the container 100 into the case 101 or for flowing the liquid in the case 101 into the container 100 is formed on the side surface of the case 101 (see Patent Document 1). ).

Further, as another example of the means for detecting the vertical position of the float as described above, as shown in FIG. 11, a float 202 disposed substantially immovably in a case 201 in a container 200, and the float 202 There is also known a displacer-type liquid level detection device that detects a liquid level with a liquid level detection element 203 that changes in voltage according to a change in buoyancy exerted on the float 202. A fuel introduction window 204 that is long in the vertical direction is formed on the side wall of the case 201, and liquid enters and exits the case 201 through the fuel introduction window 204 (see Patent Document 2).
JP 2001-31654 A JP 2003-307160 A

  In the liquid level detection devices described in Patent Documents 1 and 2, since the communication hole 101a and the fuel introduction window 204 are formed to be relatively small, the liquid in the containers 100 and 200 flows into the case 101. At the same time, the amount of inflow is regulated. For this reason, there is a problem that the rise of the float 102 or the buoyancy of the float 202 is slowed even with a sudden rise in the liquid level when fuel is supplied, and the liquid level detection reaction becomes slow.

  In addition, with the temporary inclination of the containers 100 and 200 due to the movement of the vehicle or the like on which the containers 100 and 200 are mounted, not a little liquid flows out into and out of the cases 101 and 201 from the communication hole 101a and the fuel introduction window 204. As a result, fluctuations in detection of the liquid level occur, and when the inclined state of the containers 100 and 200 continues, the liquid gradually flows into the cases 101 and 201 from the communication hole 101a and the fuel introduction window 204, and the liquid in the cases 101 and 201 The surface also rises or descends, and there is a risk of erroneous detection with respect to the original liquid level.

  Accordingly, an object of the present invention is to provide a liquid level detection apparatus that solves the above-described problems.

  In order to solve the above-mentioned problem, the invention according to claim 1 includes a container containing a liquid, a float for detecting a liquid level, a case containing the float, an inside of the case, and a liquid contained therein. A liquid level detection apparatus having a liquid communication hole that enables communication with a container is provided with variable means for changing the flow area of the liquid communication hole.

  According to the present invention, the amount of liquid flowing from the container into the case can be adjusted by the variable means in accordance with each situation such as a sudden increase / decrease in the liquid in the container or a change in the liquid level due to the inclination of the container. .

  According to a second aspect of the present invention, in the first aspect of the present invention, when the liquid is supplied to the container containing the liquid, the variable means sets the flow passage area of the communication hole so that the container is substantially horizontal and non- It is characterized by being larger than that at the time of supply.

  According to the present invention, when a large amount of liquid suddenly flows into the container when the liquid is supplied into the container, the flow passage area of the communication hole is increased by the variable means, and the large amount of liquid is immediately discharged. Can flow into the case.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the variable means may be configured so that the flow path area of the communication hole is substantially horizontal when the container containing the liquid is inclined and the container is not supplied. It is characterized in that it is smaller than the time or the communication hole is closed.

  According to the present invention, when the container is inclined, the flow area of the communication hole is made smaller by the variable means than when the container is horizontal, or the communication hole is closed so that the liquid flows out between the container and the case. The amount of input can be reduced or eliminated.

The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the communication hole is provided in a bottom portion of the case, and the variable means is disposed on a bottom wall of the container. This is characterized in that it is provided opposite to.
According to the present invention, the variable means can be arranged below the case.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, the float detects the liquid level by moving linearly in the vertical direction.

  According to the present invention, the float can be moved up and down in the vertical direction with the horizontal sectional area of the float and the horizontal sectional area of the case being substantially the same.

  According to the first aspect of the present invention, the flow area of the communication path of the case is controlled by the variable means corresponding to the change in the liquid amount or the liquid level in the container, and the liquid level is detected even by the liquid level fluctuation in the container. Can improve the accuracy.

  According to the second aspect of the present invention, when the liquid level in the container suddenly changes due to fuel supply or the like, the flow passage area in the communication hole is made larger than usual by the variable means so By following a large amount of liquid supply and allowing a large amount of liquid to flow from the inside of the container into the case, it is possible to detect the liquid level with a good response to the rapid liquid supply.

  According to the third aspect of the present invention, when the container is tilted, the communication hole is closed by the variable means to stop the inflow of the liquid into the case, and the liquid level against the temporary tilt and the continuation of the tilted state. False detection can be prevented. Further, by reducing the flow passage area of the communication hole by the variable means, it is possible to suppress the inflow of the liquid into the case and to reduce the liquid level detection fluctuation due to the temporary inclination of the container.

  According to the fourth aspect of the present invention, the variable means can be easily arranged on the lower side of the case, and the apparatus can be downsized.

  According to the fifth aspect of the present invention, the volume of the case is reduced to reduce the influence of the liquid level fluctuation in the case at the time of tilting, and in combination with the variable means, the liquid level detection at the time of the liquid level tilting is further achieved. The influence of can be reduced.

  The best mode for carrying out the present invention will be described based on the embodiment shown in FIGS.

  FIGS. 1 to 4 show Embodiment 1 of the present invention, which is applied to a liquid level detecting device for moving up and down variable means (hereinafter also referred to as variable means) for changing the flow channel area in the present invention.

  As shown in FIG. 1, a cylindrical case 3 made of a resin or the like that is less affected by fuel immersion in a container 2 such as a fuel tank or an oil tank for storing a liquid such as fuel changes the flow path area described later. It is fixed from the vicinity of the upper part of the variable means 1 to the upper wall of the container 2.

  As shown in FIG. 2, a cylindrical float 4 made of a nonmagnetic resin or the like is housed in the case 3 so as to be movable up and down. A cylindrical through hole 4a penetrating in the vertical direction is formed at the center of the. A cylindrical guide shaft 5 made of a non-magnetic resin and the like is suspended from the upper portion of the case 3 at the center of the case 3 and is less affected by fuel immersion. The float 4 can be moved up and down through the through hole 4a of the float 4. That is, when the case 3 and the guide shaft 5 are substantially perpendicular to the horizontal plane, there is a predetermined gap between the outer peripheral surface 4b of the float 4 and the inner peripheral surface 3a of the case 3, and the float 4 There is also a predetermined gap between the inner peripheral surface 4 c of the through hole 4 a and the outer peripheral surface 5 a of the guide shaft 5, and the float 4 is disposed so as to be movable up and down between the guide shaft 5 and the case 3. Therefore, the float 4 moves vertically up and down in a direction perpendicular to the upper and lower wall surfaces of the container 2 and parallel to the case 3 and the guide shaft 5. The lower end of the guide shaft 5 is spaced above the variable means 1 so as not to hinder the operation of the variable means 1 described later.

  Inside the guide shaft 5, a plurality of reed switches 6, which are magnetoelectric conversion elements, are arranged in the axial direction with a predetermined interval, that is, from the lower end portion to the upper end portion of the guide shaft 5. , The required liquid level detection accuracy is set. A magnet 7 made of a permanent magnet is embedded in the float 4 on the inner peripheral surface 4c side, and when the float 4 moves up and down, the reed switch 6 at a position facing the magnet 7 is turned on by a magnetic force. A signal is output to the outside, and the liquid level is detected based on this signal.

  Further, a bottom wall 3b is formed inside the lower portion of the case 3, and the bottom wall 3b is disposed at a position that enters a predetermined amount above the lower end opening 3c of the case 3 and is below the bottom wall 3b. On the side, a case lower space 3e is formed by extending the side wall 3d of the case 3 downward, the periphery being surrounded by the peripheral wall 3d ', and the lower side opening. Further, a circular communication hole 3f is formed through the center of the bottom wall 3b, and a liquid such as gasoline in the container 2 flows through the case 3 from the communication hole 3f.

  The flow passage area of the communication hole 3f is, for example, a large flow passage area that increases the amount of liquid flow so that the liquid level in the case 3 also rises rapidly following a sudden rise in the liquid level when gasoline is supplied. Is formed.

Below the case 3, variable means 1 for changing the flow path area is provided.
The variable means 1 for changing the channel area will be described.

  A substrate 9 is fixed to the bottom surface of the container 2. A sealing valve 8 is provided above the substrate 9, and the sealing valve 8 is a disc-shaped main body 10 and a conical valve section that is integrally formed at the center of the main body 10 and protrudes upward. 10a, the main body portion 10 moves up and down in the case lower space 3e, and the valve portion 10a with a sharp upper portion moves up and down in the communication hole 3f. Further, the relationship between the outer diameter of the valve portion 10a and the inner diameter of the communication hole 3f is that the area of the annular passage formed by the outer peripheral surface of the valve portion 10a and the communication hole 3f increases as the valve portion 10a descends. Further, when the valve portion 10a is raised to the maximum, the valve portion 10a closes the communication hole 3f.

  Further, the outer diameter of the main body portion 10 of the sealing valve 8 is formed smaller than the inner diameter of the peripheral wall 3d ′ of the case 3, and the main body portion 10 is accommodated so as to move up and down in the case lower space 3e. ing.

  The blocking valve 8 is formed of a resin or the like that is less affected by the immersion of fuel such as gasoline.

  Between the main body 10 of the blocking valve 8 and the substrate 9, there is interposed a biasing means 11 that biases the blocking valve 8 upward, which is always on the side of the communication hole 3f. In the embodiment, a coil spring is used as the biasing means. In the embodiment, as shown in the figure, a plurality is provided on the circumference centered on the axis of the blocking valve 10 at a position shifted by a predetermined distance from the center of the main body 10 to the outside.

  Further, the urging force of the coil spring 11 as the urging means 11 is set to be predetermined so that the blocking valve 8 can be opened and closed as will be described later, and the elastic performance is maintained even if immersed in the liquid material for a long time. It is made of a material that is not lost, such as SUS304.

  Further, a magnet 12 made of a permanent magnet is embedded in the center of the back surface (lower surface) of the main body 10 in the block valve 8 so that the magnet 12 is attracted downward by excitation of an electromagnet 13 described later. It has become.

  An electromagnet 13 is concentrically opposed to the magnet 12 and is relatively spaced apart from the substrate 9, and the spring 11 is disposed on the outer periphery of the electromagnet 13. The electromagnet 13 generates a magnetic force when excited by a signal from the outside, attracts the magnet 12 provided in the blocking valve 8 downward, and resists the blocking valve 8 against the upward biasing force of the spring 11. It is designed to be pulled downward.

  As described above, when the blocking valve 8 is moved downward to increase the flow area of the communication hole 3f, a sudden increase or decrease (liquid level change) of the liquid amount occurs. Therefore, the electromagnet 13 may be excited when such a rapid increase / decrease in liquid amount (liquid level change) occurs.

  In the present embodiment, when such a sudden increase in liquid amount (change in liquid level) occurs, the fuel tank of an automobile is at the time of refueling, so the refueling gun provided at the refueling port is inserted. A signal is output so that the electromagnet 13 is excited by an on operation of a detection means such as an open / close switch for detection or a switch provided in a filler pipe connecting a fuel filler port and a fuel tank to sense liquid during fueling. It has become.

  In the present embodiment, a plurality of springs 11 are arranged around the center of the blocking valve 8, but a single spring wound around the same diameter as the surroundings may be used.

Next, the operation will be described taking the case where the present invention is used for a fuel tank of a vehicle as an example.
When the fuel tank (also referred to as a container) of the vehicle on which the liquid level detection device of the first embodiment is mounted is in a normal horizontal state, as shown in FIG. 2, the main portion 10 of the blocking valve 8 is in a horizontal state, The stationary weight Mg in the vertical direction of the blocking valve 8 and the repulsive force R of the spring 11 urging the blocking valve 8 upward balance the position shown in FIG.

  In this state, the tip of the valve portion 10a of the blocking valve 8 is inserted into the case 3 in a small amount from the communication hole 3f formed at the center of the bottom wall 3b of the case 3 (referred to as a reference position). It is kept. Further, the electromagnet 13 provided on the substrate 9 is not excited and does not exert a downward attractive force on the blocking valve 8. Therefore, in this state, a predetermined amount of annular gap is secured between the inner peripheral surface of the communication hole 3f and the outer peripheral surface of the valve portion 10a, and the communication hole 3f is set to a predetermined opening amount.

  Such a state is when the amount of liquid consumption in the fuel tank (container) 2 is moderate, for example, when the amount of oil in the container 2 gradually decreases due to fuel consumption by the internal combustion engine. Is slightly open so that the liquid level in the container 2 and the liquid level in the case 3 are kept at the same liquid level.

  Accordingly, the float 4 mounted in the case 3 follows the decrease in the liquid level in the container 2 and is positioned at the same liquid level as the liquid level in the container 2, and the liquid level position is set to the reed switch 6. A normal signal level is detected by outputting a signal to the outside by a detecting means such as for example.

  Next, when a large amount of fuel suddenly flows into the fuel tank (container) 2 at the time of refueling, an open / close switch that detects insertion of a refueling gun inserted into a refueling port (not shown), or a connection between the refueling port and the fuel tank. The oil supply process is detected by detection means such as a switch for detecting the liquid (fuel) in the filler pipe, and the electromagnet 13 is excited by this detection.

  When the electromagnet 13 is excited, a magnetic force is generated, and the attraction force for attracting the magnet 12 of the blocking valve 8 by the magnetic force of the electromagnet 13 is superior to the biasing force for biasing the blocking valve 8 by the spring 11 upward. 8 descends as shown in FIG. By using a magnet as a member to be attracted on the side of the blocking valve 8, the attractive force due to the magnetic force of both the magnet 12 and the electromagnet 13 is increased, and the electromagnet 13 can be downsized.

  Further, when the blocking valve 8 is lowered, the annular gap formed by the outer peripheral surface of the valve portion 10a and the inner peripheral surface of the communication hole 3f, that is, the flow area becomes larger than that during the normal fuel consumption. Therefore, a large amount of fuel flows into the case 3 from the container 2 through the communication hole 3f, and even in the case of a sudden increase in fuel into the container, the fuel is promptly supplied into the case 3 according to the amount of supplied oil. This makes it possible to accurately detect the oil amount.

  In addition, when the liquid is rapidly discharged from the container, that is, when the fuel tank (container) 2 is damaged and the fuel leaks to the outside of the container 2, a switch that detects that the liquid is discharged suddenly. And the electromagnet 13 may be excited by the switch.

Next, a case where the vehicle or the like is inclined due to the undulation of the ground will be described.
At this time, since the fueling gun is not inserted into the fueling port, the electromagnet 13 is not excited, and the downward attractive force is not acting on the blocking valve 8. At this time, the liquid level is inclined as shown in FIG. When this inclination is so inclined that the liquid is collected on the case 3 side in the container 2, the liquid tends to flow into the case 3 from the communication hole 3f.

  At this time, the blocking valve 8 is also tilted as shown in FIG. The gravity component Mg ′ in the movable direction of the blocking valve 8 due to this inclination is Mg ′ = Mg · cos θ with respect to the self-weight component Mg in the horizontal state of the blocking valve 8, and Mg ′ is smaller than Mg. Thus, the block valve 8 is pushed up by the repulsive force R ′ of the spring 11 and the block valve 8 is raised by the amount of the gravity component Mg ′ in the movable direction of the block valve 8 being reduced. That is, the repulsive force of the spring 11 generated to keep the balance of the force applied to the blocking valve 8 is reduced by the inclination of the container 2, so that the amount of contraction of the spring 11 is less than that in the horizontal state. As a result, the position of the blocking valve 8 connected to the spring 11 moves upward, and the diameter of the communication hole 3f can be reduced or the communication hole 3f can be closed.

  As described above, when the blocking valve 8 is pushed up, the valve portion 10a formed in the blocking valve 8 is inserted deeply into the communication hole 3f of the bottom surface 3b of the case 3, and the peripheral surface of the communication hole 3f and the valve portion 10a are inserted. The opening amount due to the annular area is reduced, or the communication hole 3f is closed by the valve portion 10a. Therefore, the distribution amount of the liquid between the case 3 and the container 2 is smaller than that in the normal state, or the distribution is prevented by being fully closed. Therefore, the change in the flow rate in the case 3 due to the inclination is extremely small, or the flow rate in the case does not change, so the float 4 is maintained at the liquid surface part before the inclination, and the influence on the liquid amount detection due to the inclination of the container 2 Is reduced or eliminated.

  In addition, since the magnet 12 can adsorb iron-based foreign matter mixed in the liquid, the iron-based foreign matter floats in the vicinity of the detection device in the case 3 when refueling the container 2 or when vibration is generated. Can be prevented, a stable operation of the float 4 can be secured, and a normal water level can be detected.

  Thus, in the present invention, when the container 2 is in a normal state, when fuel is supplied into the container 2, or when the container 2 is tilted, the variable means 1 is controlled in accordance with these. This makes it possible to detect the liquid level with high accuracy in any situation.

  FIG. 7 shows an example in which the variable means 1 for changing the flow path area of the first embodiment is applied to a displacer type liquid level detection device.

  In the second embodiment, as shown in FIG. 7, a cylindrical float 24 that is less affected by fuel immersion and that is made of a non-magnetic resin or the like and that is long in the vertical direction can freely move up and down. In the center of the lower portion of the float 24, a cylindrical long hole 24a is formed upward from the lower surface. A spring 30 wound about the same diameter as the cross section of the long hole 24a is inserted into the long hole 24a. The spring 30 is in contact with the upper surface 30a of the long hole 24a and the bottom wall 3b of the case 3. ing. Further, a predetermined gap is provided between the outer peripheral surface 24b of the float 24 and the inner peripheral surface 3a of the case 3, and the float 24 is disposed so as to be movable up and down in the case 3.

  With the above-described structure, the float 24 is supported by being urged upward by the spring 30 from the bottom wall 3b of the case 3, and the buoyancy generated in the float 24 is changed by the increase or decrease of the liquid in the case 3, and according to the buoyancy. The liquid level is detected by a liquid level detecting element (piezoelectric element or resistor) (not shown) provided on the upper part of the float 24. A displacer type liquid level detection device having such a liquid level detection element is described in Patent Document 2.

  In such a displacer type, as shown in FIG. 7, the variable means 1 similar to that of the first embodiment is disposed, and the communication hole 3f similar to that of the first embodiment is formed in the case 3. Yes. The same parts as those in the first embodiment are denoted by the same reference numerals as those described above, and the description thereof is omitted.

  Also in the second embodiment, the same operation and effect as the first embodiment can be exhibited by the control of the variable means 1.

  Further, as shown in the first and second embodiments, the horizontal cross-sectional area of the case 3 at the horizontal cross-section YY is obtained by configuring the float as shown in FIG. 8 so as to move linearly in the vertical direction. Since the diameter of the float 4 in the horizontal section is substantially the same, the influence of the liquid level fluctuation in the case 3 when the container 2 is inclined can be reduced. Therefore, combined with the reduction of the influence of the liquid level fluctuation in the case 3 and the control of the variable means 1, the liquid level detection accuracy can be further increased, and the case 3 can be further downsized.

  As another embodiment of the present invention, as shown in FIG. 9, the float 4A is supported by a rotation fulcrum 40 in the case 3A, and the liquid level is detected by moving the curve around the rotation fulcrum 40. It can also be applied to things.

  The present invention can also be applied to a container for storing a liquid other than the fuel tank of the vehicle, and is not limited to the fuel tank of the vehicle.

1 is a longitudinal sectional view showing Example 1 of the present invention. FIG. 2 is an enlarged vertical cross-sectional view of the liquid level detection device unit of FIG. The longitudinal cross-sectional view which showed the force component in FIG. The longitudinal cross-sectional view which sucked and lowered the blocking valve in FIG. The longitudinal cross-sectional view which shows the state which the container inclined in FIG. FIG. 6 is a longitudinal sectional view showing force components in FIG. 5. The longitudinal cross-sectional view which shows Example 2 of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is schematic of this invention, (a) is a schematic longitudinal cross-sectional view, (b) is the YY sectional view taken on the line of (a). It is the schematic which shows the other Example of this invention, (a) is a schematic longitudinal cross-sectional view, (b) is the XX sectional view taken on the line of (a). The longitudinal stage figure which shows the container and liquid level detection apparatus which used the detection method by the conventional reed switch. The longitudinal cross-sectional view which shows the container and liquid level detection apparatus which used the detection method by the conventional displacer type.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid level detection apparatus 2 Container 3 Case 3f Communication hole 4 Float 8 Sealing valve which is variable means

Claims (5)

  A liquid level having a container containing liquid, a float for detecting the liquid level, a case containing the float, and a liquid communication hole enabling communication between the inside of the case and the container containing the liquid The liquid level detection apparatus according to claim 1, further comprising variable means for changing a flow path area of the liquid communication hole.   2. The variable means according to claim 1, wherein when the liquid is supplied to the container containing the liquid, the flow passage area of the communication hole is made larger than when the container is substantially horizontal and not supplied. Liquid level detection device.   The variable means is characterized in that when the container containing liquid is inclined, the flow passage area of the communication hole is made smaller than when the container is substantially horizontal and not supplied, or the communication hole is closed. The liquid level detection device according to claim 1 or 2.   The said communication hole is provided in the bottom part of the said case, The said variable means is arrange | positioned on the bottom wall of a container, and it provided in opposition to the said communication hole, The Claim 1 thru | or 3 characterized by the above-mentioned. Liquid level detection device.   The liquid level detection device according to claim 1, wherein the float detects a liquid level by moving linearly in a vertical direction.

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