JP2014085140A - Liquid level sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level sensor capable of measuring even a low liquid level.SOLUTION: A float 3 mounted with a magnet 4 is floated on a liquid level of liquid stored in a tank 2 and vertically moves in response to changes in the liquid level of the liquid. A rod 5 is inserted into a through hole 3a of the float 3 to guide vertical movement of the float 3. The rod 5 is mounted with magnetic sensors 6a, 6b. Further, the rod 5 is provided with a stopper 5a that comes into contact with the bottom of the float 3 to prevent the float 3 from going through. The bottom of the float 3 is provided with a protrusion 3c protruding toward a tank bottom side other than a contact surface contacting the stopper 5a.

Description

  The present invention relates to a liquid level sensor, and more particularly, to a liquid level sensor that is mounted on a tank that stores liquid such as automobile gasoline or engine oil and that measures the liquid level of the liquid using magnetic force. Is.

  Conventionally, a liquid level sensor as shown in FIG. 4 is known as an example of this type of liquid level sensor (Patent Document 1). As shown in the figure, the liquid level sensor 100 is floated on the liquid level of the liquid stored in the tank 200, and moves up and down according to the change in the liquid level of the liquid. A magnet 102, a rod 103 that is inserted into a through hole provided in the float 101 and guides the vertical movement of the float 101, and magnetic sensors 104a and 104b attached to the upper and lower ends of the rod 103 are provided. ing. According to the above configuration, the float 101 moves up and down according to the fluctuation of the liquid level, and the outputs of the magnetic sensors 104a and 104b also fluctuate accordingly. Therefore, the liquid level is based on the outputs of the magnetic sensors 104a and 104b. Level can be measured.

  The float 101 and the rod 103 described above are accommodated in an accommodation case 105. The storage case 105 covers the cylindrical housing 105a in which the float 101 and the rod 103 are stored, the lower lid 105b attached so as to block the lower opening of the cylindrical housing 105a, and the upper opening of the cylindrical housing 105a. And an upper lid 105c attached to the head. An opening for the liquid level sensor 100 is provided in the ceiling of the tank 200. The housing case 105 is attached by inserting the housing case 105 into the tank 200 through the opening and overlapping the upper lid 105c on the ceiling of the tank 200. ing.

  Since the storage case 105 is attached to the ceiling of the tank 200 as described above, the lower lid 105 b is disposed slightly above the bottom surface of the tank 200. Therefore, as shown in FIG. 5, when the liquid level becomes lower than (the height H1 from the bottom surface of the tank to the lower lid 106) + (the draft H2 of the float 101), the lower lid 105b in which the bottom surface of the float 101 serves as a stopper. There is a problem that the liquid level cannot be detected any more because the liquid level is lower than that of the lower lid 105b. The draft H2 is the distance from the liquid level when the float 101 is floating to the bottom surface of the float 101.

  Therefore, it is conceivable to provide the rod 103 and the housing case 105 so that the lower lid 105b is at the same height as the bottom surface of the tank 200. However, the tank 200 ceiling-bottom surface due to variations in the distance between the tank 200 ceiling-bottom surface and the liquid weight. Considering the absorption of the change in the distance between them, it is difficult to provide it with such accuracy. In addition, it is conceivable to provide the lower lid 105b integrally on the bottom surface of the tank 200. However, providing the lower lid 105b integrally with the tank 200 complicates the structure and causes a problem in cost.

Japanese Utility Model Publication No. 60-20019

  Then, this invention makes it a subject to provide the liquid level sensor which can also measure a low liquid level.

  The invention according to claim 1 for solving the above-described problem is a float floated on a liquid level of a liquid stored in a tank and moves up and down according to a change in the liquid level of the liquid, and is attached to the float A magnetic member attached to the guide member, and a guide member for guiding the float to move up and down, and a magnetic sensor attached to the guide member, based on the output of the magnetic sensor. In the liquid level sensor for measuring the liquid level of the liquid, the guide member is provided with a stopper that is in contact with the bottom surface of the float to prevent the float from being removed, and the stopper is disposed on the bottom surface of the float. The liquid level sensor is provided with a convex portion that protrudes toward the bottom surface of the tank with respect to the abutting surface that abuts against the tank.

  According to a second aspect of the present invention, the float is provided with a through-hole through which the guide member passes, and the protrusion is provided on the entire bottom surface of the float excluding the peripheral edge of the through-hole. It exists in the liquid level sensor of Claim 1 characterized by these.

  As described above, according to the first aspect of the present invention, the bottom surface of the float is provided with the convex portion that protrudes more toward the tank bottom surface than the contact surface that contacts the stopper. Even if it is provided slightly above, the tip of the convex portion may abut against the tank bottom surface. In this case, it is possible to measure a liquid level that is lower by the height from the bottom surface of the tank to the stopper than a float having no convex portion. Even when the tip of the convex portion does not reach the bottom surface of the tank, it is possible to measure a liquid level that is lower than the float without the convex portion by the amount that the convex portion protrudes.

  According to invention of Claim 2, a convex part can be provided with the simple structure which only makes the through-hole periphery provided in the float into a recessed part. Moreover, the volume of a convex part can be enlarged and the draft of a float can be made low.

(A) is a longitudinal cross-sectional view which shows one Embodiment of the liquid level sensor of this invention, (B) is the figure which looked at the float shown to FIG. 1 (A) from the bottom face side. It is a partial longitudinal section of the liquid level sensor of the present invention in other embodiments. It is the figure which looked at the float in other embodiments from the bottom side. It is a longitudinal cross-sectional view which shows an example of the conventional liquid level sensor. It is a fragmentary longitudinal cross-sectional view of FIG. 4 for demonstrating the conventional problem.

  Hereinafter, an embodiment of the liquid level sensor of the present invention will be described with reference to FIG. FIG. 1A is a longitudinal sectional view showing an embodiment of the liquid level sensor of the present invention. FIG. 1B is a view of the float shown in FIG. As shown in FIG. 1A, the liquid level sensor 1 is floated on the liquid level of the liquid stored in the tank 2 and moves up and down in accordance with the change in the liquid level. An attached magnet 4, a float 3 is fitted so as to be movable up and down, a rod 5 as a guide member for guiding the up and down movement of the float 3, and magnetic sensors 6 a and 6 b attached to the rod 5 are provided. Yes.

  The rod 5 is provided in a bar shape extending in the vertical direction, and the float 3 is fitted in a freely movable manner by passing through a through hole 3 a provided in the float 3. A flange-like stopper 5 a that contacts the bottom surface of the float 3 and prevents the float 3 from coming off is provided at the lower end of the rod 5. The stopper 5 a is provided in a disk shape, and the diameter thereof is larger than the diameter of the through hole 3 a provided in the float 3. The stopper 5a is in contact with the bottom surface of the float 3 so that the magnet 4 built in the float 3 is not positioned below the magnetic sensor 6a, and restricts downward movement. The stopper 5a may be formed integrally with the rod 5, or may be provided separately from the rod 5 and attached to the rod 5.

  A flange-shaped mounting flange 5 b for mounting the liquid level sensor 1 to the tank 2 is provided at the upper end of the rod 5. The mounting flange 5b is provided in a disk shape, for example, and the diameter thereof is larger than the diameter of the opening 2a for inserting the liquid level sensor 1 provided on the ceiling of the tank 2 into the tank 2. . In addition, the attachment flange 5b should just be provided larger than the opening 2a, and the shape is not restricted to a disk shape. The rod 5 passes the float 3 between the mounting flange 5b and the stopper 5a, and the float 3 moves up and down along the rod 5 between the mounting flange 5b and the stopper 5a.

  As shown in FIG. 1, the float 3 is formed in a columnar shape, and a through hole 3 a that penetrates the rod 5 is formed in the center thereof. Further, the bottom surface of the float 3 is provided with a recess 3b at the peripheral edge of the through hole 3a, and a stopper 5a abuts against the bottom surface of the recess 3b to prevent the rod 5 from coming off. And the convex part 3c provided in the outer side rather than this recessed part 3b protrudes in the tank 2 bottom face side rather than the contact surface contact | abutted with the stopper 5a.

  The magnet 4 is built in the float 3 described above. The magnetic sensors 6a and 6b are mounted in a rod 5 formed in a pipe shape. Specifically, the magnetic sensor 6a is attached above the stopper 5a at the lower end of the rod 5. The magnetic sensor 6 b is attached below the attachment flange 5 b at the upper end of the rod 5. The magnetic sensors 6a and 6b are composed of, for example, a Hall element, a magnetoresistive element, or the like, and detect the strength of the magnetic field that changes according to the distance from the magnet 4 that moves up and down.

  Therefore, when the liquid level increases, for example, the float 3 rises following the increasing liquid level, the distance between the magnet 4 and the upper magnetic sensor 6b approaches, and the magnetic field detected by the magnetic sensor 6b increases. The distance between the magnet 4 and the lower magnetic sensor 6a is increased, and the magnetic field detected by the magnetic sensor 6a is weakened. In contrast, when the liquid level decreases, the float 3 descends following the decreasing liquid level, the distance between the magnet 4 and the upper magnetic sensor 6b increases, and the magnetic field detected by the magnetic sensor 6b is weak. At the same time, the distance between the magnet 4 and the lower magnetic sensor 6a becomes closer, and the magnetic field detected by the magnetic sensor 6a becomes stronger. That is, the liquid level can be measured based on the difference between the magnetic fields detected by the magnetic sensor 6a and the magnetic sensor 6b.

  The liquid level sensor 1 having the above-described configuration is inserted into the tank 2 from the opening 2a for the liquid level sensor 1 provided on the ceiling of the tank 2, and is attached to the tank 2 by overlapping the mounting flange 5b on the ceiling of the tank 2. It is done. At this time, the lower end of the rod 5 is positioned slightly above the bottom surface of the tank 2. In the example shown in FIG. 1, since the distance between the bottom surface of the tank 2 and the stopper 5a is lower than the height of the convex portion 3c, when the liquid level is low, the tip of the convex portion 3c is moved before the float 3 hits the stopper 5a. It contacts the bottom surface of the tank 2. In this case, when the liquid level becomes higher than the draft H2 of the float 3, the float 3 floats up, and the liquid level can be measured. Compared to the conventional float 101 shown in FIG. The liquid level can be measured as low as the height H1 from the bottom surface to the stopper 5a.

  Further, in the example shown in FIG. 2, since the distance H1 between the bottom surface of the tank 2 and the stopper 5a is higher than the height H3 of the convex portion 3c, the convex portion even when the float 3 hits the stopper 5a when the liquid level is low. 3c does not reach the bottom of the tank 2. Even in this case, when the liquid level becomes higher than (draft 3 of the float 3) + (distance H4 between the convex portion 3c and the bottom surface of the tank 2) (<H1), the float 3 is lifted and the liquid level is increased. It becomes possible to measure, and it is possible to measure to a liquid level lower by the height H3 of the convex portion 3c than the conventional float 101 shown in FIG. 4 having no convex portion 3c.

  Further, according to the liquid level sensor 1 described above, since the convex portion 3c is provided on the entire portion of the bottom surface of the float 3 except the peripheral portion of the through hole a, the peripheral portion of the through hole 3a provided in the float 3 is recessed. The convex portion 3c can be provided with a simple configuration that is only 3b. Moreover, the volume of the convex part 3c can be enlarged and the draft H2 of the float 3 can be made low.

  Further, according to the liquid level sensor 1 described above, the stopper 5a is in contact with the bottom surface of the float 3 so that the magnet 4 built in the float 3 is not located below the magnetic sensor 6a, and the stopper 5a The movement is restricted. Thereby, even if the liquid level is lowered, the magnet 4 is not positioned below the magnetic sensor 6a. Therefore, the direction of the magnetic field input to the magnetic sensor 6a is such that the magnet 4 is positioned above the magnetic sensor 6a. This is the opposite of the case where the liquid level is not measured.

  According to the liquid level sensor 1 described above, the concave portion 3b is provided only in the center of the float 3, and the entire outside of the concave portion 3b is the convex portion 3c. However, the present invention is not limited to this. For example, as shown in FIG. 3, you may make it provide the some convex part 3c so that the through-hole 3a may be enclosed. However, as shown in FIG. 1, the volume of the convex part 3c can be increased and the draft H2 can be lowered by making the entire outside of the concave part 3b a convex part 3c.

  Further, according to the liquid level sensor 1 described above, the two magnetic sensors 6a and 6b are provided at the upper and lower ends of the rod 5, but the present invention is not limited to this. The present invention may be applied to the liquid level sensor 1 in which three or more magnetic sensors are arranged in the vertical direction of the rod 5.

  Further, according to the liquid level sensor 1 described above, the rod 5 penetrates the through hole 3a provided in the float 3, but the present invention is not limited to this. For example, the rod 5 may be provided in a pipe shape and applied to the liquid level sensor 1 in which the float 3 is accommodated.

  Further, the above-described embodiments are merely representative forms of the present invention, and the present invention is not limited to the embodiments. That is, various modifications can be made without departing from the scope of the present invention.

2 Tank 3 Float 3a Through-hole 3b Concave part 3c Convex part 4 Magnet 5 Rod 5a Stopper 6a Magnetic sensor 6b Magnetic sensor

Claims (2)

A float that floats on the liquid level of the liquid stored in the tank and moves up and down in response to a change in the liquid level of the liquid, a magnet attached to the float, and the float are fitted so as to freely move up and down. In a liquid level sensor that includes a guide member that guides the vertical movement of the float, and a magnetic sensor attached to the guide member, and that measures the liquid level of the liquid based on the output of the magnetic sensor,
The guide member is provided with a stopper that comes into contact with the bottom surface of the float to prevent the float from coming off,
The liquid level sensor, wherein the bottom surface of the float is provided with a convex portion that protrudes toward the bottom surface of the tank from the contact surface that contacts the stopper. The float is provided with a through hole through which the guide member passes,
2. The liquid level sensor according to claim 1, wherein the convex portion is provided on an entire portion of the bottom surface of the float except for a peripheral edge portion of the through hole.

Images