JP2016145743A - Liquid level detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level detector in which the number of sensors for detecting a position of a float in a fuel tank is reduced.SOLUTION: A slide part 28 is connected to one end of a link mechanism 35 and slides a magnetic substance according to vertical movement of a float 38. A magnetic sensor 24 that outputs a detection result corresponding to a distance from the slide part 28 is disposed at a position most closest to the slide part 28 when the float 38 is at a predetermined reference position. A processing part 23 detects a position of a liquid surface of a fuel on the basis of the detection result received from the magnetic sensor 24. The processing part 23 stores high/low information indicating that the float 38 is at a position higher or lower than the reference position, switches high/low of the high/low information upon detecting that the detection result of the magnetic sensor 24 reaches the reference position, and outputs a different calculation result for the detection result of the magnetic sensor 24 between a case when the high/low information shows high and a case when the high/low information shows low.SELECTED DRAWING: Figure 1

Description

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

  Patent Document 1 discloses a level gauge that displays the amount of gasoline in a tank of a motorcycle or the like. The level gauge disclosed in Patent Document 1 is switched to a float that floats on gasoline in a tank, an instruction lever that swings through an arm when the float moves up and down, a magnet provided at the tip of the instruction lever, and an instruction lever A plurality of reed switches and a plurality of lamps respectively connected to each reed switch. The indicator lever swings according to the vertical movement of the float, and activates one of the reed switches. Depending on the operation of the reed switch, a lamp indicating that the gasoline amount is full or a lamp indicating that the gasoline is empty is turned on.

  Patent Document 2 includes an annular float that floats on fuel and includes a magnet, a cylinder that is inserted through the float, and a plurality of magnetoresistive elements that are arranged in a line along the depth direction of the fuel in the cylinder. And a microcomputer for receiving outputs of a plurality of magnetoresistive elements. The microcomputer detects the position of the float based on the magnitude of the magnetic resistance detected by the plurality of magnetoresistive elements.

Japanese Utility Model Publication No. 58-8127 JP 2002-71431 A

  In the technique disclosed in Patent Document 1, the upper and lower positions of the float are detected by providing a plurality of switches such as a switch corresponding to a full gasoline amount and a switch corresponding to an empty gasoline amount. In the technique disclosed in Patent Document 2, a plurality of magnetoresistive elements are arranged in a line along the depth direction of the fuel, and the upper and lower positions of the float are determined depending on which magnetoresistive element detects the largest magnetoresistance. To detect. As described above, in the technologies disclosed in Patent Document 1 and Patent Document 2, the upper and lower positions of the float are detected by using a plurality of sensors, which increases the cost.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a liquid level detection device capable of reducing the number of sensors for detecting the position of a float in a fuel tank.

  In order to solve the above-described problem, an aspect of the present invention is a liquid level detection device that is attached to a fuel tank and detects the position of a fuel liquid level, and one end portion of the float disposed in the fuel tank has one end. The connected link mechanism, connected to the other end of the link mechanism, and outputs a detection result according to the distance between the slide part that slides the magnetic body in accordance with the vertical movement of the float and the slide part. A magnetic sensor provided at a position closest to the slide portion when located at a predetermined reference position; and a processing unit for detecting a position of a fuel level based on a detection result received from the magnetic sensor. The processing unit holds high and low information indicating whether the float is at a position higher or lower than the reference position, and when detecting that the reference position has been reached from the detection result of the magnetic sensor, the processing unit switches between high and low information. Different calculation results are output with respect to the detection result of the magnetic sensor depending on whether the information indicates that the float is higher than the reference position or lower.

  According to this aspect, the height information is used to identify whether the float is higher or lower than the reference position, and when the detection result of the magnetic sensor corresponds to two positions of the slide portion, the height information The position can be specified.

  ADVANTAGE OF THE INVENTION According to this invention, the liquid level detection apparatus which reduces the number of sensors for detecting the position of the float in a fuel tank can be provided.

It is a figure for demonstrating the liquid level detection apparatus of an Example. It is an enlarged view for demonstrating a magnetic sensor and a slide part. It is a figure for demonstrating the detection result of the magnetic sensor according to the distance with a slide part. It is a figure for demonstrating the calculation process of the fuel quantity in a process part.

  FIG. 1 is a diagram for explaining a liquid level detection device 10 according to the embodiment. The liquid level detection device 10 is provided in the fuel tank 12 and detects the position of the liquid level 14 of the fuel in the fuel tank 12. The calculation result of the liquid level detection device 10 is sent to a display meter on the instrument panel and displayed as a fuel gauge.

  The fuel tank 12 has an opening 12a, and a fuel pump 16 for supplying fuel to the opening 12a is provided. The liquid level detection device 10 is fixed to the fuel pump 16 and is attached to the fuel tank 12 together with the fuel pump 16.

  The liquid level detection apparatus 10 includes a base unit 20, a support unit 22, a processing unit 23, a magnetic sensor 24, a lid unit 26, a rail 27, a slide unit 28, a link mechanism 35, and a float 38. The lid portion 26 closes the opening 12a of the fuel tank 12. The liquid level detection device 10 is divided into a member disposed outside the fuel tank 12 from the lid portion 26 and a member disposed inside the lid portion 26. The liquid level detection device 10 includes a base unit 20, a support unit 22, a processing unit 23, and a magnetic sensor 24 as members provided outside the fuel tank 12 that do not come into contact with the fuel in the fuel tank 12. A rail 27, a slide portion 28, a link mechanism 35, and a float 38 are provided as members provided in the fuel tank 12 that come into contact with the fuel.

  The float 38 floats on the fuel and is displaced in the vertical direction in accordance with a change in the position of the liquid level 14 of the fuel. FIG. 1 shows the position of the float 38 with respect to the liquid level 14 indicated by a solid line, the position of the float 38a with respect to the liquid level 14a indicated by a one-dot chain line, and the position of the float 38b with respect to the liquid level 14b indicated by a two-dot chain line.

  The link mechanism 35 connects the float 38 to the slide portion 28 on the fuel pump 16 side, and rotates according to the displacement of the float 38. The link mechanism 35 includes a first joint 30, a first arm 32, a second joint 34, and a second arm 36.

  One end portion of the first arm 32 is rotatably connected to the slide portion 28 by the first joint 30, and the other end portion of the first arm 32 is connected to one end portion of the second arm 36 by the second joint 34. . The other end of the second arm 36 is connected to the float 38. One end portion of the link mechanism 35 is connected to the float 38, and the other end portion of the link mechanism 35 is connected to the slide portion 28. The second joint 34 is rotatably connected to the fuel pump 16 and swings the first arm 32 and the second arm 36 by rotation.

  The slide portion 28 is coupled to the link mechanism 35 and is supported by the rail 27 so as to be slidable. The rail 27 is provided so as to be substantially horizontal. The slide portion 28 slides in a substantially horizontal direction according to the displacement of the float 38. As shown in FIG. 1, when the position of the float 38 becomes higher, the slide portion 28 moves to the right side, and when the position of the float 38 becomes lower, the slide portion 28 moves to the left side. Thus, the position of the fuel liquid level 14 corresponds to the vertical position of the float 38 and corresponds to the position of the slide portion 28.

  The lid 26 closes the opening 12a of the fuel tank 12 so that the processing unit 23 and the magnetic sensor 24 do not come into contact with fuel. A magnetic sensor 24 is provided above the lid portion 26. The magnetic sensor 24 outputs an output signal corresponding to the distance from the slide unit 28 to the processing unit 23. The processing unit 23 detects the position of the fuel level 14 based on the output signal output from the magnetic sensor 24. In this way, the magnetic sensor 24 can be configured to be non-contact with the fuel outside the lid portion 26.

  The magnetic sensor 24 is fixed to the support portion 22 of the base portion 20. The base portion 20 is integral with the lid portion 26 and can be removed from the opening 12a. The magnetic sensor 24 is provided at a position close to the rail 27 while being shielded from the slide portion 28 by the lid portion 26. The magnetic sensor 24 is provided at a position vertically above a predetermined position of the rail 27, and is eccentric from the center position of the rail 27. As a result, the detection result of the magnetic sensor 24 can be set differently when the slide portion 28 sliding left and right moves to the rightmost side and when moved to the leftmost side.

  In the liquid level detection device 10, the slide amount of the slide portion 28 relative to the displacement amount of the float 38 can be shortened by the link mechanism 35. Thereby, the slidable distance of the slide part 28 is shortened, and the displacement of the float 38 can be detected by one magnetic sensor 24.

  FIG. 2 is an enlarged view for explaining the magnetic sensor 24 and the slide portion 28. The magnetic sensor 24 is attached, for example, at a position slightly decentered from the position vertically above the center of the rail 27, and is provided at a position closest to the slide portion 28 when the float 38 is at the predetermined reference position 40. The reference position 40 corresponds to the vicinity of the central position where the liquid level 14 is between the highest and the lowest. Compared with the case where the magnetic sensor 24 is attached to one end of the rail 27, the distance near the center of the rail 27 is set as the reference position 40, whereby the distance that the slide portion 28 is farthest from the magnetic sensor 24 can be shortened. The number of can be reduced.

  The slide portion 28 includes a ferromagnetic material 28a. The ferromagnetic body 28a is a magnet formed of, for example, iron or nickel. The slide part 28 slides according to the vertical movement of the float 38. The magnetic sensor 24 outputs a detection result corresponding to the distance between the magnetic sensor 24 and the slide portion 28.

  FIG. 3 is a diagram for explaining the detection result of the magnetic sensor 24 in accordance with the distance from the slide portion 28. The vertical axis shown in FIG. 3 indicates the magnetoresistance change rate output by the magnetic sensor 24, and the horizontal axis indicates the distance.

  The horizontal axis in FIG. 3 corresponds to the distance between the magnetic sensor 24 and the slide portion 28, and the magnetoresistance change rate on the vertical axis in FIG. 3 is a value that changes according to the distance between the magnetic sensor 24 and the slide portion 28. The distance shown in FIG. 3 is indicated by a plus when the slide part 28 is on the right side of the reference position 40 and is indicated by a minus when the slide part 28 is on the left side of the reference position 40.

  The magnetic sensor 24 detects the largest magnetoresistance change rate R at the reference position 40 and detects the magnetoresistance change rate R that decreases as the distance from the reference position 40 increases. Although the magnetic sensor 24 has a magnetoresistance change rate R, the distance D to the slide portion 28 is unknown.

  The magnetoresistance change rate R1 when the distance is minus D1, that is, the detection result when the fuel level 14 is the lowest, the magnetoresistance change rate R0 when the distance is plus D2, that is, the fuel level 14 is the highest. It is set to be larger than the detection result at the time. When the distance is plus D2, the magnetoresistance change rate R is the smallest and the minimum value R0 is detected. That is, when the magnetoresistive change rate R, which is the detection result of the magnetic sensor 24, is R1 or less, it indicates that the liquid level 14 of the fuel tank 12 is on the full side. Whether the magnetoresistance change rate R is equal to or less than R1 is determined by a process described later. The magnetic sensor 24 outputs an output signal of the magnetoresistance change rate R to the processing unit 23 as a detection result.

  The processing unit 23 calculates a fuel amount indicating the remaining amount of fuel in the fuel tank 12 based on the detection result from the magnetic sensor 24. The processing unit 23 holds in advance advance information for determining the level of the liquid level 14 with respect to the reference position 40. The processing unit 23 includes a magnetoresistance change rate R0 detected at the highest position of the fuel liquid level 14, a magnetoresistance change rate R1 detected at the lowest position, and a magnetoresistance change detected at the reference position 40. The rate R2 is held as prior information. The processing unit 23 determines whether the current liquid level 14 is higher or lower than the reference position 40 using the prior information, and holds the determination result as high / low information.

  The processing unit 23 executes height determination processing for determining the height with respect to the reference position 40 based on the detection result of the magnetic sensor 24. When the detection result of the magnetic sensor 24 is equal to or less than the predetermined value R1, the processing unit 23 determines that the liquid level 14 of the fuel tank 12 is full, and the liquid level 14 is higher than the reference position 40 as height information. Information indicating this is retained. When the fuel decreases and the detection result of the magnetic sensor 24 reaches the maximum value R2, the processing unit 23 determines that the liquid level 14 is at the reference position 40, and when the detection result of the magnetic sensor 24 decreases from the maximum value R2, the liquid level 14 Is determined to be lower than the reference position 40, and information indicating that the liquid level 14 is lower than the reference position 40 is held as height information. Thus, the processing unit 23 holds the height information indicating the current level of the liquid level 14 with respect to the reference position 40, and the float 38 reaches the reference position 40 when the detection result of the magnetic sensor 24 reaches the maximum value. As high and low information is switched.

  After the height determination process, the processing unit 23 changes the calculation result according to the height information with respect to the detection result of the magnetic sensor 24 and outputs the result to the display meter to display the fuel amount in the fuel tank 12.

  FIG. 4 is a diagram for explaining fuel amount calculation processing in the processing unit 23. The graph shown in FIG. 4A shows the result of executing the inversion process on the detection result of the magnetic sensor 24, and the graph shown in FIG. 4B shows the correction process after the inversion process of the detection result of the magnetic sensor 24. Indicates the execution result. In FIG. 4A, the detection result of the magnetic sensor 24 before performing the inversion process is indicated by a dotted line, and the detection result of the magnetic sensor 24 after executing the inversion process is indicated by a solid line.

  As illustrated in FIG. 4A, the processing unit 23 receives the detection result of the magnetoresistance change rate R <b> 3 from the magnetic sensor 24. At this time, since it is unknown whether the distance to the magnetoresistance change rate R3 is d1 or d2, the processing unit 23 determines whether the distance is d1 or d2 based on the height information.

The processing unit 23 determines the execution of the detection result reversal processing based on the height information indicating that it is higher than the reference position 40. The processing unit 23 obtains a magnetoresistance change rate R4 that has been inverted by the following equation from the magnetoresistance change rate R2 at the reference position 40 and the magnetoresistance change rate R3 at d1 by reversal processing.
R4 = R2 + (R2-R3)

  The processing unit 23 outputs the magnetoresistive change rate R3 or the magnetoresistive change rate R4 according to the height information with respect to the magnetoresistive change rate R3 that is the detection result of the magnetic sensor 24. As described above, the processing unit 23 calculates different results for the detection result of the magnetic sensor 24 depending on whether the height information indicates that the float 38 is at a higher position than the reference position 40 or indicates that the float 38 is at a lower position. Is output.

  As shown in FIG. 4B, a correction process for calibrating the magnetoresistance change rate after the reversal process shown in FIG. 4A is performed to calculate the fuel amount indicating the remaining amount of fuel as an analog value. . In this example, a fuel amount of 10 indicates that the fuel tank 12 is full, and a fuel amount of 0 indicates that the fuel tank 12 is empty. The processing unit 23 outputs the calculation result to the display meter, and displays the fuel amount on the display meter. The processing unit 23 may calculate the fuel amount based on the height information and the magnetic resistance change rate with reference to a table held in advance.

  In addition, although the process part 23 showed the aspect provided integrally with the magnetic sensor 24, it is not restricted to this aspect, It may be contained in some ECUs and may be provided in a display meter.

  The present invention is not limited to the above-described embodiments and modifications, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. The configuration shown in each drawing is for explaining an example, and can be appropriately changed as long as the configuration can achieve the same function.

  DESCRIPTION OF SYMBOLS 10 Liquid level detection apparatus, 12 Fuel tank, 12a Opening part, 14 Liquid level, 16 Fuel pump, 20 Base part, 22 Support part, 23 Processing part, 24 Magnetic sensor, 26 Cover part, 27 Rail, 28 Slide part, 28a Ferromagnetic material, 30 First joint, 32 First arm, 34 Second joint, 35 Link mechanism, 36 Second arm, 38 Float, 40 Reference position.

Claims (1)

A liquid level detection device that is attached to a fuel tank and detects the position of a fuel liquid level,
A link mechanism having one end connected to a float disposed in the fuel tank;
A slide part connected to the other end of the link mechanism and sliding the magnetic body in accordance with the vertical movement of the float;
A magnetic sensor provided at a position closest to the slide portion when the float is at a predetermined reference position;
A processing unit for detecting the position of the liquid level of the fuel based on the detection result received from the magnetic sensor,
The processing unit holds height information indicating whether the float is located at a position higher or lower than the reference position, and detects that the reference position has been reached from the detection result of the magnetic sensor. When the height information indicates that the float is at a position higher than the reference position, and when the position information indicates that the float is at a lower position, different calculation results are output with respect to the detection result of the magnetic sensor. A liquid level detection device characterized by that.

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