JP6032844B2 - Liquid level detector - Google Patents

Description

  The present invention relates to a liquid level detection device, and more particularly, to a liquid level detection that is mounted on a tank for storing a liquid such as gasoline or engine oil of an automobile and detects the liquid level using the magnetic force. It relates to the device.

  Conventionally, a magnetic liquid level gauge as shown in FIG. 23 is known as an example of this type of liquid level detector (Patent Document 1). As shown in the figure, the magnetic liquid level gauge 800 is attached to the outside of the oil tank, and can move within the glass tube 851 constituting a part of the liquid introducing portion 850 according to the change in the liquid level. The float 801 is provided. A first magnet 802A and a second magnet 802B are provided on the upper and lower surfaces of the float 801 so that the polarities are opposite to each other (that is, the same poles face each other). A sensor case 803 is attached to the glass tube 851, and a plurality of sensor portions 804A to 804E are accommodated in the sensor case 803 at intervals in the vertical direction. Each of the sensor units 804A to 804E includes an angle sensor that detects the angle formed by the magnetic lines of force of the first magnet 802A and the second magnet 802B, and a magnetic strength sensor that detects that the float 801 has reached the vicinity due to the magnetic strength. It is equipped with.

  According to the magnetic liquid level meter 800 described above, first, the sensor unit 804A to 804E having the maximum output from the magnetic intensity sensor is selected, and then the angle sensor output from the selected sensor unit is set to the liquid level. Is converted into That is, in the above-described magnetic liquid level gauge 800, the sensor unit that maximizes the output of the magnetic sensor is specified as the sensor unit closest to the float, and the angle sensor of the specified sensor unit, that is, the closest to the float 801. The liquid level is detected using an angle sensor.

JP 2009-236615 A

  However, in the above-described magnetic liquid level gauge 800, in order to specify a sensor unit having an angle sensor closest to the float 801, it is necessary to provide a magnetic intensity sensor in each of the sensor units 804A to 804E. A plurality of types of sensors are provided in each of the sensor units 804A to 804E, which causes a problem that the device configuration becomes complicated.

  Therefore, as a result of intensive studies on the relationship between the position of the magnet and the output value of the magnetic intensity sensor arranged in a row, the present inventors have obtained a plurality of values by using the difference value of the output values of the adjacent magnetic intensity sensors. It was found that the liquid level can be detected using only the magnetic intensity sensor.

  Hereinafter, the detection of the liquid level using only the magnetic intensity sensor will be described with reference to FIGS.

  FIG. 24 shows the magnet position and the output value of the magnetic intensity sensor S [k] (k is a natural number of 1 from 1 to N−1), the output value of the magnetic intensity sensor S [k + 1], and these outputs. It is an example of the graph which shows the relationship with the difference value D [k] of a value. Considering the difference value D [k] obtained by subtracting the output value of the magnetic strength sensor S [k + 1] adjacent thereto from the output value of the magnetic strength sensor S [k], as shown in FIG. There is a magnet position where the output of each sensor is balanced between [k] and the magnetic intensity sensor S [k + 1], and the difference value D [k] is 0 at that magnet position. This magnet position is defined as a zero cross position P [k]. When the magnet is positioned on the magnetic strength sensor S [k] side (left side in the figure) from the zero cross position P [k], the output value of the magnetic strength sensor S [k] is greater than the output value of the magnetic strength sensor S [k + 1]. It becomes larger and the sign of the difference value D [k] becomes positive (that is, D [k]> 0). Conversely, when the magnet is positioned on the magnetic strength sensor S [k + 1] side (right side in the figure) from the zero cross position P [k], the output value of the magnetic strength sensor S [k + 1] is larger than the output value of S [k]. Therefore, the sign of the difference value D [k] is negative (that is, D [k] <0). Further, when the magnet is closest to the magnetic intensity sensor S [k], the difference value D [k] is the maximum value, and when the magnet is closest to the magnetic intensity sensor S [k + 1], the difference value D [k] is the minimum value. It becomes. In the sign determination, when D [k] = 0, it may be included in either positive (D [k]> 0) or negative (D [k] <0).

  FIG. 25 is an example of a graph showing the relationship between the magnet position and a plurality of difference values D [i] (i is a plurality of natural numbers from 1 to N−1). In FIG. 25, as an example, the difference values D [1] to D [3] in the configuration including the magnetic intensity sensors S [1] to S [4] (N = 4) are shown.

  In the section T [1] on the left side of the figure from the zero cross position P [1], all the signs of the difference values D [1] to D [3] are positive. The section T [1] includes the magnet position where the difference value D [1] is the maximum value, and the difference values D [2] and D [3] are the maximum magnet position and the minimum value. Does not include the magnet position.

  In the section T [2] between the zero cross position P [1] and the zero cross position P [2], the sign of the difference value D [1] is negative, and the sign of the difference values D [2] and D [3] is It is positive. The section T [2] includes a magnet position where the difference value D [1] is the minimum value and a magnet position where the difference value D [2] is the maximum value. The maximum magnet position and the minimum magnet position are not included.

  In the section T [3] between the zero cross position P [2] and the zero cross position P [3], the sign of the difference values D [1] and D [2] is negative, and the sign of the difference value D [3] is It is positive. The section T [3] includes a magnet position where the difference value D [2] is the minimum value and a magnet position where the difference value D [3] is the maximum value. The maximum magnet position and the minimum magnet position are not included.

  In the section T [4] on the right side of the figure from the zero cross position P [3], all the signs of the difference values D [1] to D [3] are negative. The section T [4] includes a magnet position at which the difference value D [3] is a minimum value. For the difference values D [1] and D [2], the magnet position and the minimum value are at a maximum value. Does not include the magnet position.

  From this, if the sign of the difference value D [1] is positive, it can be specified that the magnet position is in the section T [1], and the difference values D [2] and D are included in the section T [1]. Since [3] does not include the maximum magnet position and the minimum magnet position, the difference values D [2] and D [3] monotonously change (monotonically increase) in the section T [1]. That is, the magnet position (that is, the liquid level) is uniquely determined with respect to the difference values D [2] and D [3]. Therefore, the liquid level can be detected based on one or both of the difference values D [2] and D [3].

  If the sign of the difference value D [1] is negative and the sign of the difference value D [2] is positive, it can be specified that the magnet position is in the section T [2], and the section T [2] Does not include the maximum magnet position and the minimum magnet position for the difference value D [3], the difference value D [3] changes monotonously in the section T [2]. The magnet position is uniquely determined with respect to the value of D [3]. Therefore, the liquid level can be detected based on the difference value D [3].

  If the sign of D [2] is negative and the sign of the difference value D [3] is positive, it can be specified that the magnet position is in the section T [3], and the section T [3] Since the difference value D [1] does not include the maximum magnet position and the minimum magnet position, the difference value D [1] changes monotonously in the section T [3], that is, the difference value D [ 1] uniquely determines the magnet position. Therefore, the liquid level can be detected based on the difference value D [1].

  If the sign of the difference value D [3] is negative, it can be specified that the magnet position is in the section T [4], and the difference values D [1] and D [2] are included in the section T [4]. ] Does not include the magnet position having the maximum value and the magnet position having the minimum value, the difference values D [1] and D [2] change monotonously in the section T [4], that is, the difference value D [ The magnet position is uniquely determined for the values of 1] and D [2]. Therefore, the liquid level can be detected based on one or both of the difference values D [1] and D [3].

  In FIG. 25, the number N of the magnetic intensity sensors S is 4, but even when the number N is 5 or more, the magnetic intensity sensors S [1] to S [N] are spaced apart from each other in the vertical direction. If they are sequentially arranged, each difference value D [i] appears so that each maximum value and minimum value are sequentially arranged in the left-right direction in the figure, as in FIG. ] Are also arranged in order in the left-right direction in the figure, and can be considered in the same manner as described above. In FIG. 26, as an example of a graph showing the relationship between the magnet position and a plurality of difference values D [i] (i is a plurality of natural numbers from 1 to N−1), magnetic intensity sensors S [1] to S [ 8] Difference values D [1] to D [7] in the configuration with (N = 8) will be described.

  That is, the difference value D [j] of the difference value D [i] (j is a natural number of 1 from 1 to N−2) is negative and the difference value D [i] When the sign of the difference value D [j + 1] is positive, it can be specified that the magnet position is in the section T [j + 1], and the difference value D [j] and the difference value D [j + 1] are included in the section T [j + 1]. ] Is not included, and the magnet position that is the maximum value and the magnet position that is the minimum value are not included for the difference value D [a] other than] (where a is one or a plurality of natural numbers other than j and j + 1 from 1 to N−1). Therefore, the difference value D [a] changes monotonously in the section T [j + 1]. Therefore, the liquid level can be detected based on the difference level D [a] and the liquid level detection reference information H [a] corresponding to the difference value D [a].

  When the sign of the difference value D [1] is positive, it is specified that the magnet position is in the section T [1], and the difference value D [other than the difference value D [1] is included in the section T [1]. b] (b is one or a plurality of natural numbers from 2 to N−1), and does not include the magnet position that is the maximum value and the magnet position that is the minimum value. D [b] changes monotonously. Therefore, the liquid level can be detected based on the difference level D [b] and the liquid level detection reference information H [b] corresponding to the difference value D [b].

  Further, when the sign of the difference value D [N−1] is negative, it is specified that the section T [N] has a magnet position, and the section T [N] has a value other than the difference value D [N−1]. Since the difference value D [c] (c is one or a plurality of natural numbers from 1 to N−2) does not include the maximum magnet position and the minimum magnet position, the section T [N] The difference value D [c] changes monotonously. Therefore, the liquid level can be detected based on the difference level D [c] and the liquid level detection reference information H [c] corresponding to the difference value D [c].

  Therefore, since the liquid level can be detected using only a plurality of magnetic intensity sensors, a simple configuration using only one type of sensor can be achieved.

  However, in the detection of the liquid level using the configuration as described above, since the liquid level is detected using the difference value D that changes monotonously with respect to the position of the magnet in the section T, such a difference value D is The ratio of the change of the difference value D to the change of the position of the magnet, that is, the liquid level (that is, the absolute value of the inclination of the change) is small, so that it is difficult to detect a minute change in the liquid level with high accuracy. There was room for improvement in terms of detection accuracy at the liquid level.

  The present invention aims to solve this problem. That is, an object of the present invention is to provide a liquid level detecting device having a simple configuration using only one type of sensor and good detection accuracy.

  In order to achieve the above object, the invention described in claim 1 includes a magnet that is moved in the vertical direction according to the liquid level of the liquid stored in the tank, as shown in the basic configuration diagram of FIG. A plurality of magnetic intensity sensors S [1] to S [N] (N is a natural number of 4 or more), which are sequentially arranged in the vertical direction and spaced from each other and output a value corresponding to the distance from the magnet. The difference value D [i] is calculated by subtracting the output value of the magnetic intensity sensor S [i + 1] from the output value of the magnetic intensity sensor S [i] (i is a plurality of natural numbers from 1 to N-1). The difference value calculation means P1 to perform, and a part or all of the range between the position of the magnet where the difference value D [i] is maximum and the position of the magnet where the difference value D [i] is minimum The relationship between the difference value D [i] and the liquid level. High-accuracy liquid level detection reference information G [i] between the position of the magnet where the difference value D [i] is maximum and the position of the magnet where the difference value D [i] is minimum. Standard precision liquid level detection reference information H [i] indicating the relationship between the difference value D [i] and the liquid level in part or all of the range other than the range, and predetermined high precision detection conditions are stored. Information storage means Q1 and liquid level detection means P2, and the liquid level detection means P2 (A) the difference value D [j] (j of the difference value D [i] (Aα) when the sign of 1 is a negative natural number from 1 to N−2) and the sign of the difference value D [j + 1] of the difference values D [i] is positive. The difference value D [a] (a is 1 to N−1) other than the difference value D [j] and the difference value D [j + 1]. High-precision liquid level detection reference information corresponding to the difference value D [j] and the difference value D [j] when one or more natural numbers other than j and j + 1) satisfy the high-precision detection condition. G [j], or the liquid level is detected based on high-precision liquid level detection reference information G [j + 1] corresponding to the difference value D [j + 1] and the difference value D [j + 1], and (Aβ ) When the difference value D [a] does not satisfy the high accuracy detection condition, the difference value D [a] and the standard accuracy liquid level detection reference information H [a] corresponding to the difference value D [a] (Bα) a difference other than the difference value D [1] when the sign of the difference value D [1] of the difference value D [i] is positive. The value D [b] (b is one or more natural numbers from 2 to N-1) is the high precision When the degree detection condition is satisfied, the liquid level is detected based on the difference value D [1] and high-precision liquid level detection reference information G [1] corresponding to the difference value D [1], and (Bβ ) When the difference value D [b] does not satisfy the high accuracy detection condition, the standard accuracy liquid level detection reference information H [b] corresponding to the difference value D [b] and the difference value D [b] And (Cα) the difference value D [N−1] when the sign of the difference value D [N−1] of the difference value D [i] is negative. ] Other than the difference value D [c] (where c is one or more natural numbers from 1 to N−2) satisfy the high-precision detection condition, the difference value D [N−1] and the difference Detecting the liquid level based on high-precision liquid level detection reference information G [N-1] corresponding to the value D [N-1], (Cβ) When the difference value D [c] does not satisfy the high-precision detection condition, standard accuracy liquid level detection reference information H [c corresponding to the difference value D [c] and the difference value D [c] The liquid level detection device is configured to detect the liquid level based on the above.

  In order to achieve the above object, the invention described in claim 2 includes a magnet that is moved up and down in accordance with the liquid level of the liquid stored in the tank, as shown in the basic configuration diagram of FIG. A plurality of magnetic intensity sensors S [1] to S [N] (N is a natural number of 4 or more), which are sequentially arranged in the vertical direction and spaced from each other and output a value corresponding to the distance from the magnet. The difference value D [i] is calculated by subtracting the output value of the magnetic intensity sensor S [i + 1] from the output value of the magnetic intensity sensor S [i] (i is a plurality of natural numbers from 1 to N-1). The difference value calculation means P1 to perform, and a part or all of the range between the position of the magnet where the difference value D [i] is maximum and the position of the magnet where the difference value D [i] is minimum The relationship between the difference value D [i] and the liquid level. High-accuracy liquid level detection reference information G [i] between the position of the magnet where the difference value D [i] is maximum and the position of the magnet where the difference value D [i] is minimum. Standard precision liquid level detection reference information H [i] indicating the relationship between the difference value D [i] and the liquid level in part or all of the range other than the range, and predetermined high precision detection conditions are stored. Information storage means Q1 and liquid level detection means P2, and the magnetic strength sensor S [1] outputs an output value when the position of the magnet is at one end in the movable range. The magnetic strength sensor S [N] is disposed so as to be maximized, and is disposed so that the output value is maximized when the position of the magnet is the other end in the movable range. The detection means P2 is (A Of the difference values D [i], the difference value D [j] (j is a natural number of 1 from 1 to N−2) is negative and the difference value D [i] When the sign of the difference value D [j + 1] is positive, (Aα) the difference value D [a] other than the difference value D [j] and the difference value D [j + 1] (a is 1 to N−1). High-precision liquid level detection reference information corresponding to the difference value D [j] and the difference value D [j] when one or more natural numbers other than j and j + 1) satisfy the high-precision detection condition. G [j], or the liquid level is detected based on high-precision liquid level detection reference information G [j + 1] corresponding to the difference value D [j + 1] and the difference value D [j + 1], and (Aβ ) When the difference value D [a] does not satisfy the high-precision detection condition, the difference value D [a] and the difference value D The liquid level is detected based on the standard accuracy liquid level detection reference information H [a] corresponding to a], and (B ′) the sign of the difference value D [1] among the difference values D [i]. Is positive, the liquid level is detected based on the difference value D [1] and high-precision liquid level detection reference information G [1] corresponding to the difference value D [1], and (C ′) When the sign of the difference value D [N-1] in the difference value D [i] is negative, the high-precision liquid corresponding to the difference value D [N-1] and the difference value D [N-1] The liquid level detecting device is configured to detect the liquid level based on surface level detection reference information G [N-1].

  The invention described in claim 3 is the invention described in claim 1 or 2, wherein the liquid level detecting means P2 is (A1) one difference value D selected from the difference value D [i]. [M] (M is a natural number of 1 from 1 to N−1), the sign determination is started. (A2) When the sign of the difference value D [M] is determined to be positive, the difference value D The sign determination is sequentially advanced toward [1], and the sign is finally determined to be positive and the difference value D [j [j + 1] (j is a natural number of one of M−1 to 1). j] when the sign is first determined to be negative, (A2α) When the difference value D [a] satisfies the high-precision detection condition, the difference value D [j] and the high-precision liquid level detection Reference information G [j], or the difference value D [j + 1] and the high-accuracy liquid level detection reference information The liquid level is detected based on [j + 1], and (A2β) When the difference value D [a] does not satisfy the high accuracy detection condition, the difference value D [a] and the standard accuracy liquid level detection The liquid level is detected based on the reference information H [a]. (A3) When the sign of the difference value D [M] is determined to be negative, toward the difference value D [N−1]. The determination of the sign is sequentially advanced, the sign is finally determined to be negative in the difference value D [j] (j is one natural number from M to N−2), and the sign is first determined in the difference value D [j + 1]. (A3α) When the difference value D [a] satisfies the high-precision detection condition, the difference value D [j] and the high-precision liquid level detection reference information G [j] Or the difference value D [j + 1] and the high-accuracy liquid level detection reference information G [j 1], and (A3β) when the difference value D [a] does not satisfy the high accuracy detection condition, the difference value D [a] and the standard accuracy liquid level detection criterion The liquid level is detected based on the information H [a].

  In the invention described in claim 4, in the invention described in claim 3, when the number N of the magnetic intensity sensors S [1] to S [N] is an even number, the difference value D [i] N / 2 is selected in advance as the code determination start number M of the difference value D [M] for starting the code determination, or when the number N is an odd number, the code determination start number M is (N−1) / 2 or (N + 1) / 2 is selected in advance.

  The invention described in claim 5 is the difference value D [k] () in which, in the invention described in claim 3, the liquid level detection means determines the sign last in the difference value D [i]. k is the difference value D [M] for starting the code determination of the difference value D [i] so that the determination of the code in the next detection starts from the first natural number of 1 to N−1. ] Is selected as the code determination start number M.].

  The invention described in claim 6 is the invention described in any one of claims 1 to 5, wherein the difference value D [a] is a difference value D [j] of the difference values [i]. −1] and the difference value D [j + 2].

  According to the first aspect of the present invention, (A) the difference value D [j] (j is a natural number of 1 from 1 to N−2) among the plurality of difference values D [i] When the sign is negative and the sign of the difference value D [j + 1] among the plurality of difference values D [i] is positive, (Aα) other than the difference value D [j] and the difference value D [j + 1] When the difference value D [a] (a is one or more natural numbers other than j and j + 1 from 1 to N−1) satisfies the predetermined high-precision detection condition, the difference value D [j] and the difference value D High-precision liquid level detection reference information G [j] corresponding to [j] or high-precision liquid level detection reference information G [j + 1] corresponding to difference value D [j + 1] and difference value D [j + 1]. The liquid level is detected on the basis of the difference value D [a] and the difference value D when the difference value D [a] does not satisfy the high-precision detection condition. When the liquid level is detected based on the standard accuracy liquid level detection reference information H [a] corresponding to [a], and the sign of (B) difference value D [1] is positive, (Bα) difference value When the difference value D [b] other than D [1] (b is one or more natural numbers from 2 to N−1) satisfies the high-precision detection condition, the difference value D [1] and the difference value D When the liquid level is detected based on the high-precision liquid level detection reference information G [1] corresponding to [1] and the difference value D [b] does not satisfy the high-precision detection condition, the difference value D The liquid level is detected based on the standard precision liquid level detection reference information H [b] corresponding to [b] and the difference value D [b]. (C) The sign of the difference value D [N−1] is negative. In the case of (Cα) difference value D [c] other than difference value D [N−1] (c is one or more natural numbers from 1 to N−2) is high. When the degree detection condition is satisfied, the liquid level is detected based on the high accuracy liquid level detection reference information G [N-1] corresponding to the difference value D [N-1] and the difference value D [N-1]. , (Cβ) When the difference value D [c] does not satisfy the high accuracy detection condition, based on the standard accuracy liquid level detection reference information H [c] corresponding to the difference value D [c] and the difference value D [c]. To detect the liquid level.

  The operation of the first aspect of the invention will be described with reference to FIGS.

  FIG. 2 is an example of a graph showing the relationship between the magnet position and a plurality of difference values D [i] (i is a plurality of natural numbers from 1 to N−1). In FIG. 2, as an example, the difference values D [1] to D [3] in the configuration including the magnetic intensity sensors S [1] to S [4] (N = 4) are shown.

  In FIG. 2, the difference values D [1] to D [3] in the sections T [1] to T [4] partitioned by the zero cross positions P [1] to P [3] have a predetermined relationship with each other. Have

  That is, in the section T [1], the difference value D [2] that changes monotonously in the section T [1] and the difference value D [1] that has the maximum magnet position in the section T [1]. The difference value D [1] is at the maximum value when the difference value D [2] is at the magnet position at which the predetermined value w1 is reached. Therefore, in the magnet position range (A) in which the difference value D [2] in the section T [1] is equal to or greater than the predetermined value w1, the difference value D [1] changes monotonously in the range from the maximum value to 0. In this range (A), the amount of change of the difference value D [1] is larger than the amount of change of the difference value D [2], that is, the difference value D [1] is greater than the difference value D [2]. However, the change of the value with respect to the change of the magnet position (that is, the change of the liquid level) is large (the absolute value of the gradient of the change of the difference value is large). Therefore, when it is specified that the magnet position is in the section T [1], when the difference value D [2] is equal to or larger than the predetermined value w1 (that is, when a predetermined high-precision detection condition is satisfied), the magnet position is In the range (A), the detection accuracy can be improved by detecting the liquid level using the difference value D [1] instead of the difference value D [2]. Further, the difference value D [3] and the difference value D [1] that change monotonously in the section T [1] have the same relationship.

  In the section T [2], the difference value D [3] that changes monotonously in the section T [2] and the difference value D [1] that has a minimum magnet position in the section T [2] When the magnet position is such that the value D [3] is the predetermined value w2, the difference value D [1] has a minimum value. Therefore, in the range (B) of the magnet position where the difference value D [3] in the section T [2] is equal to or less than the predetermined value w2, the difference value D [1] changes monotonously in the range from 0 to the minimum value. In this range (B), the amount of change of the difference value D [1] is larger than the amount of change of the difference value D [3], that is, the difference value D [1] is greater than the difference value D [3]. However, the change of the value with respect to the change of the magnet position is large. Therefore, when it is specified that the magnet position is in the section T [2], when the difference value D [3] is equal to or smaller than the predetermined value w2 (that is, when a predetermined high-precision detection condition is satisfied), the magnet position is In the range (B), the detection accuracy can be improved by detecting the liquid level using the difference value D [1] instead of the difference value D [3].

  Further, in the section T [2], the difference value D [3] that changes monotonously in the section T [2] and the difference value D [2] that has the maximum magnet position in the section T [2] The relationship between the difference value D [2] and the difference value D [1] in the section T [1] is the same. Therefore, when the difference value D [3] is greater than or equal to the predetermined value w3 when the magnet position is specified in the section T [2], the difference between the magnet position is the difference value D [2] from the maximum value to zero. In this case, the detection accuracy can be improved by detecting the liquid level using the difference value D [2] instead of the difference value D [3].

  In the section T [3], the difference value D [1] that changes monotonously in the section T [3] and the difference value D [2] that has a minimum magnet position in the section T [3] The relationship is the same as the relationship between the difference value D [3] and the difference value D [1] in the section T [2]. Therefore, when the difference value D [1] is equal to or smaller than the predetermined value w4 when the magnet position is specified in the section T [3], the difference between the magnet position is 0 to the minimum value. In this case, the detection accuracy can be improved by detecting the liquid level using the difference value D [2] instead of the difference value D [1].

  In addition, in the section T [3], the difference value D [1] that changes monotonously in the section T [3] and the difference value D [3] that has the maximum magnet position in the section T [3] The relationship between the difference value D [2] and the difference value D [1] in the section T [1] is the same. Therefore, when the difference value D [1] is greater than or equal to the predetermined value w5 when the magnet position is specified in the section T [3], the difference between the magnet position and the difference value D [3] is 0 from the maximum value. In this case, the detection accuracy can be improved by detecting the liquid level using the difference value D [3] instead of the difference value D [1].

  In the section T [4], the difference value D [2] that changes monotonously in the section T [4] and the difference value D [3] that has a minimum magnet position in the section T [4] The relationship is the same as the relationship between the difference value D [3] and the difference value D [1] in the section T [2]. Therefore, when the difference value D [2] is equal to or smaller than the predetermined value w6 when the magnet position is specified in the section T [4], the difference between the magnet position is 0 to the minimum value. In this case, the detection accuracy can be improved by detecting the liquid level using the difference value D [3] instead of the difference value D [2].

  In FIG. 2, the number N of the magnetic intensity sensors S is 4, but even when the number N is 5 or more, the magnetic intensity sensors S [1] to S [N] are sequentially arranged in the vertical direction with a space therebetween. If they are arranged, as in FIG. 2, each difference value D [i] appears so that each maximum value and minimum value are arranged in order in the left-right direction in the figure, and each difference value D [i] Zero-cross positions P [1] to P [N-1] that become 0 are also arranged in order in the left-right direction in the figure, and can be considered in the same manner as described above. In FIG. 3, as an example of a graph showing the relationship between the magnet position and a plurality of difference values D [i] (i is a plurality of natural numbers from 1 to N−1), magnetic intensity sensors S [1] to S [ 8] Difference values D [1] to D [7] in the configuration with (N = 8) will be described.

  That is, (A) the sign of the difference value D [j] (j is a natural number of 1 from 1 to N−2) among the plurality of difference values D [i] is negative and the plurality of differences When the sign of the difference value D [j + 1] among the values D [i] is positive, it is specified that the magnet position is in the section T [j + 1] partitioned by the zero cross position P [i], and (Aα) A difference value D [a] (a is one or a plurality of natural numbers other than j and j + 1 from 1 to N−1) monotonously changing in this section T [j + 1] is a predetermined high-precision detection condition When this condition is satisfied, the high-accuracy liquid level detection reference information G [j] corresponding to the difference value D [j] and the difference value D [j] having a minimum magnet position in the section T [j + 1], or A difference value D [j + 1] having a maximum magnet position in this section T [j + 1] and By detecting the liquid level based on the high-precision liquid level detection reference information G [j + 1] corresponding to the fraction value D [j + 1], the detection accuracy is improved as compared with the detection using the difference value D [a]. it can. Further, when (Aβ) difference value D [a] does not satisfy the high-precision detection condition, standard accuracy liquid level detection reference information H [a] corresponding to difference value D [a] and difference value D [a] By detecting the liquid level based on this, it is possible to detect the standard level liquid level using the difference value D [a] when the high-precision detection condition is not satisfied.

  (B) When the sign of the difference value D [1] is positive, it is specified that the magnet position is in the section T [1], and (Bα) changes monotonously in the section T [1]. When the difference value D [b] (b is one or a plurality of natural numbers from 2 to N−1) satisfies the high-precision detection condition, the difference in which the magnet position becomes the maximum value in this section T [1]. By detecting the liquid level based on the highly accurate liquid level detection reference information G [1] corresponding to the value D [1] and the difference value D [1], detection using the difference value D [b] is performed. Compared to the detection accuracy. Further, when (Bβ) difference value D [b] does not satisfy the high accuracy detection condition, standard accuracy liquid level detection reference information H [b] corresponding to difference value D [b] and difference value D [b] By detecting the liquid level based on this, it is possible to detect the standard level liquid level using the difference value D [b] when the high-precision detection condition is not satisfied.

  Also, (C) when the sign of the difference value D [N−1] is negative, it is specified that the magnet position is in the section T [N], and (Cα) is monotonous in this section T [N]. When the changing difference value D [c] (c is one or more natural numbers from 1 to N−2) satisfies the high-precision detection condition, the magnet position that is the minimum value in this section T [N] By detecting the liquid level based on the high-accuracy liquid level detection reference information G [N-1] corresponding to a certain difference value D [N-1] and the difference value D [N-1], the difference value D The detection accuracy can be improved as compared with the detection using [c]. Further, when the (Cβ) difference value D [c] does not satisfy the high accuracy detection condition, the standard accuracy liquid level detection reference information H [c] corresponding to the difference value D [c] and the difference value D [c] By detecting the liquid level based on this, it is possible to detect the standard level liquid level using the difference value D [c] when the high-precision detection condition is not satisfied.

  Therefore, when a predetermined high-precision detection condition is satisfied, the liquid level can be detected using a difference value having a larger rate of change with respect to a change in the magnet position, so a simple configuration using only one type of sensor. Can accurately detect the liquid level.

  According to the second aspect of the present invention, the magnetic intensity sensor S [1] is arranged so that the output value becomes maximum when the position of the magnet is one end in the movable range, and the magnetic intensity sensor S [1] The sensor S [N] is arranged so that the output value becomes maximum when the position of the magnet is the other end in the movable range, and (A) the difference value of the difference values D [i] When the sign of D [j] (j is a natural number of 1 from 1 to N−2) is negative and the sign of the difference value D [j + 1] of the difference values D [i] is positive (Aα) difference value D [a] other than difference value D [j] and difference value D [j + 1] (a is one or more natural numbers other than j and j + 1 from 1 to N−1). When the predetermined high-precision detection condition is satisfied, the high precision corresponding to the difference value D [j] and the difference value D [j] The liquid level is detected based on the liquid level detection reference information G [j] or the high-precision liquid level detection reference information G [j + 1] corresponding to the difference value D [j + 1] and the difference value D [j + 1]. , (Aβ) When the difference value D [a] does not satisfy the high accuracy detection condition, based on the standard accuracy liquid level detection reference information H [a] corresponding to the difference value D [a] and the difference value D [a]. When the level of the liquid level is detected and (B ′) the difference value D [1] of the difference value D [i] is positive, it corresponds to the difference value D [1] and the difference value D [1]. When the liquid level is detected based on the high-accuracy liquid level detection reference information G [1], and the sign of the difference value D [N−1] of the difference value D [i] is negative, Based on the difference value D [N-1] and the highly accurate liquid level detection reference information G [N-1] corresponding to the difference value D [N-1] To detect the Le.

  According to the second aspect of the present invention, when the predetermined high-precision detection condition is satisfied by the same operation as the first aspect of the present invention, a larger difference value of the rate of change with respect to the change of the magnet position is obtained. Therefore, the liquid level can be detected with high accuracy with a simple configuration using only one type of sensor. Further, in the section T [1] on the magnetic strength sensor S [1] side from the zero cross position P [1], the difference value D [1] monotonously toward the maximum value as the distance from the zero cross position P [1] increases. In addition, the difference value D [N−1] is separated from the zero cross position P [N−1] in the section T [N] on the magnetic intensity sensor S [N] side from the zero cross position P [N−1]. Accordingly, the magnet position (that is, the liquid level) is uniquely determined with respect to the difference value D [1] or the difference value D [N−1] in these sections. The liquid level can be detected based on the value D [1] or the difference value D [N−1]. Further, in these sections T [1] or T [N], the difference value D [1] or the difference value D [N−1] changes monotonously from 0 to the maximum value or from 0 to the minimum value. The absolute value of the gradient of change is large, so that the liquid level can be detected with high accuracy.

  According to the third aspect of the invention, (A1) sign from one difference value D [M] selected from the difference value D [i] (M is one natural number from 1 to N−1). (A2) When the sign of the difference value D [M] is determined to be positive, the sign determination is sequentially advanced toward the difference value D [1], and the difference value D [j + 1] (j is , M-1 to 1 (natural number 1) when the sign is finally determined to be positive and the difference value D [j] is first determined to be negative (A2α) difference value D [ When a] satisfies the high-precision detection condition, the difference value D [j] and the high-precision liquid level detection reference information G [j], or the difference value D [j + 1] and the high-precision liquid level detection reference information G [ j + 1] is detected, and when the difference value D [a] does not satisfy the high-precision detection condition, the difference is detected. The liquid level is detected based on the fraction value D [a] and the standard accuracy liquid level detection reference information H [a], and (A3) the difference is determined when the sign of the difference value D [M] is determined to be negative. The sign determination is sequentially advanced toward the value D [N−1], and finally the sign is determined to be negative in the difference value D [j] (j is one natural number from M to N−2) and When the sign is first determined to be positive in the difference value D [j + 1], (A3α) When the difference value D [a] satisfies the high-precision detection condition, the difference value D [j] and the high-precision liquid level detection The liquid level is detected based on the reference information G [j] or the difference value D [j + 1] and the high-precision liquid level detection reference information G [j + 1], and the (A3β) difference value D [a] is high-precision. When the detection condition is not satisfied, based on the difference value D [a] and the standard accuracy liquid level detection reference information H [a] To detect the liquid level.

  That is, the sign of one difference value D [M] selected from a plurality of difference values D [i] is determined, and if the sign is positive, the difference value D [N− Since the sign up to 1] is positive, the sign is judged toward the difference value D [1] opposite to the difference value D [N−1], or if the sign is negative, the difference value D Since the sign from [M] to the difference value D [1] is negative, by determining the sign toward the difference value D [N−1] opposite to the difference value D [1], By determining the sign only for a part of the difference values D without determining the sign for all of the plurality of difference values D [i], the section where the magnet position is located can be specified. Detection can be performed faster.

  According to the fourth aspect of the present invention, when the number N of the magnetic intensity sensors S [1] to S [N] is an even number, the difference value for starting the code determination among the plurality of difference values D [i]. N / 2 is selected in advance as the code determination start number M of D [M], or (N−1) / 2 or (N + 1) / 2 is selected in advance as the code determination start number M when the number N is an odd number. Has been. Accordingly, since the determination of the sign is started from the difference value D [M] at the center or substantially the center among the plurality of difference values D [i], for example, the difference located at both ends of the plurality of difference values D [i]. The maximum number of code determinations can be reduced as compared with the case where the code determination is started from the value D [1] or the difference value D [N-1], and therefore the liquid level is detected faster. Can do.

  According to the fifth aspect of the present invention, the difference value D [k] (k is one natural number from 1 to N−1) of which the sign is finally determined among the plurality of difference values D [i]. ) Is selected as the code determination start number M of the difference value D [M] for starting the code determination from the difference value D [i] so that the code determination in the next detection is started. Thereby, since the determination of the sign is started in the next detection of the liquid level for the difference value D [k] in which the determination of the sign is finally performed in the detection of the current liquid level, the difference value D [k] is used. There is a high possibility that there is a magnet position in the vicinity of the defined zero-cross position P [k]. Therefore, by detecting the sign from the difference value D [k], the liquid level can be detected more quickly. it can.

  According to the sixth aspect of the present invention, the difference value D [a] is at least one of the difference value D [j−1] and the difference value D [j + 2]. When the magnet position is specified to be in a certain section T [h] (h is a natural number from 1 to N), the minimum value of the difference value D [j] is present in this section T [h]. There is a minimum value of the difference value D [j−1] in a section T [h−1] (where h ≧ 2) immediately adjacent to the section T [h], and this section T [h] Has the maximum value of the difference value D [j + 1], and the maximum value of the difference value D [j + 2] is present in the section T [h + 1] (where h ≦ N−1) immediately adjacent to the section T [h]. There is. Therefore, by detecting the liquid level using at least one of the difference value D [j−1] and the difference value D [j + 2], the change most occurs in the section T [h] specified as having a magnet position. The liquid level can be detected using the difference value D having a large absolute value of the inclination, and the liquid level can be detected with higher accuracy.

It is a figure which shows the basic composition of the liquid level detection apparatus of this invention. It is an example (the number N of magnetic intensity sensors = 4) which shows the relation between a magnet position and a plurality of difference values D [i]. It is an example (the number N of magnetic intensity sensors = 8) which shows the relation between a magnet position and a plurality of difference values D [i]. It is a schematic block diagram of the liquid level detection apparatus of the 1st Embodiment of this invention. It is the figure which showed typically the connection relation of the structural member of the liquid level detection apparatus of FIG. The position of the magnet in the liquid level detection apparatus of FIG. 4, a plurality of difference values D [1] to D [3], high accuracy liquid level detection reference information G [1] to G [3], and standard accuracy liquid level It is an example of the graph which shows the relationship between level detection reference information H [1] -H [3]. It is a flowchart which shows an example of the process (liquid level detection process 1) based on this invention which CPU of the microcomputer with which the control part of FIG. 5 is provided performs. The position of a magnet and a plurality of difference values D [1] to D [4], high accuracy in a liquid level detecting apparatus provided with five magnetic intensity sensors as a modification of the liquid level detecting apparatus of the first embodiment It is an example of the graph which shows the relationship between liquid level detection reference information G [1] -G [4] and standard precision liquid level detection reference information H [1] -H [4]. The process according to the present invention (liquid level) executed by the CPU of the microcomputer provided in the control unit of the liquid level detecting apparatus having five magnetic intensity sensors as a modification of the liquid level detecting apparatus of the first embodiment It is a flowchart which shows an example of the detection process 1a). FIG. 10 is a continuation of the flowchart of FIG. 9. The position of the magnet and a plurality of difference values D [1] to D [5] in the liquid level detecting device including six magnetic intensity sensors as a modification of the liquid level detecting device of the first embodiment, high accuracy It is an example of the graph which shows the relationship between liquid level detection reference information G [1] -G [5] and standard precision liquid level detection reference information H [1] -H [5]. The process according to the present invention (liquid level) executed by the CPU of the microcomputer provided in the control unit of the liquid level detecting apparatus having six magnetic intensity sensors as a modification of the liquid level detecting apparatus of the first embodiment It is a flowchart which shows an example of the detection process 1b). It is a continuation of the flowchart of FIG. It is a schematic block diagram of the liquid level detection apparatus of the 2nd Embodiment of this invention. The position of the magnet and a plurality of difference values D [1] to D [3] and high-precision liquid level detection reference information G [1] to G [3] in the liquid level detection device of the second embodiment of the present invention. 4 is an example of a graph showing a relationship between standard accuracy liquid level detection reference information H [1] and H [3]. It is a flowchart which shows an example of the process (liquid level detection process 2) which concerns on this invention which CPU of the microcomputer with which the control part of the liquid level detection apparatus of 2nd Embodiment is provided is performed. The position of the magnet and a plurality of difference values D [1] to D [4], high accuracy in a liquid level detector having five magnetic intensity sensors as a modification of the liquid level detector of the second embodiment It is an example of the graph which shows the relationship between liquid level detection reference information G [1] -G [4] and standard precision liquid level detection reference information H [1] -H [4]. The process according to the present invention (liquid level) executed by the CPU of the microcomputer provided in the control unit of the liquid level detecting apparatus having five magnetic intensity sensors as a modification of the liquid level detecting apparatus of the second embodiment It is a flowchart which shows an example of the detection process 2a). It is a continuation of the flowchart of FIG. The position of a magnet and a plurality of difference values D [1] to D [6], high accuracy in a liquid level detecting apparatus provided with six magnetic intensity sensors as a modification of the liquid level detecting apparatus of the second embodiment It is an example of the graph which shows the relationship between liquid level detection reference information G [1] -G [5] and standard precision liquid level detection reference information H [1] -H [5]. The process according to the present invention (liquid level) executed by the CPU of the microcomputer provided in the control unit of the liquid level detection apparatus having six magnetic intensity sensors as a modification of the liquid level detection apparatus of the second embodiment It is a flowchart which shows an example of the detection process 2b). It is a continuation of the flowchart of FIG. It is a figure which shows an example of the magnetic-type liquid level meter as the conventional liquid level detection apparatus. It is an example of the graph which shows the relationship between a magnet position, the output value of magnetic intensity sensor S [k], the output value of magnetic intensity sensor S [k + 1], and the difference value D [k] of these output values. It is an example (the number N of magnetic intensity sensors = 4) which shows the relation between a magnet position and a plurality of difference values D [i]. It is an example (the number N of magnetic intensity sensors = 8) which shows the relation between a magnet position and a plurality of difference values D [i].

(First embodiment)
Below, the liquid level detection apparatus of the 1st Embodiment of this invention is demonstrated with reference to FIGS.

  FIG. 4 is a schematic configuration diagram of the liquid level detecting device according to the first embodiment of the present invention. FIG. 5 is a diagram schematically showing the connection relationship of the constituent members of the liquid level detecting device of FIG. 6 shows the position of the magnet in the liquid level detection apparatus of FIG. 4, a plurality of difference values D [1] to D [3], high-precision liquid level detection reference information G [1] to G [3], and It is an example of the graph which shows the relationship between standard precision liquid level detection reference information H [1] -H [3]. FIG. 7 is a flowchart showing an example of the process (liquid level detection process 1) according to the present invention executed by the CPU of the microcomputer included in the control unit of FIG.

  As shown in FIG. 4, the liquid level detection device of the present embodiment (indicated by reference numeral 1 in the figure) includes a magnet 3, a rod 4, and a plurality of magnetic intensity sensors S [1] to S [4]. And a control unit 10 (FIG. 5). The liquid level detecting device 1 is disposed in the tank 2.

  The magnet 3 is formed in, for example, an annular shape through which an after-mentioned rod 4 can be inserted through the inner edge 3a. The magnet 3 is, for example, one in which a magnet is attached to a float member having a large buoyancy, or a synthetic resin containing a material that generates magnetic force in the form of a foam so as to float on the liquid surface of the liquid stored in the tank 2 Etc.

  The rod 4 is formed in a long cylindrical shape, for example. The rod 4 is disposed in the tank 2 so that the axial direction is parallel to the vertical direction (vertical direction).

  A flange-like stopper 4 a is provided at the lower end of the rod 4. The stopper 4 a has a disc shape and is formed in a disc shape having a diameter larger than the diameter of the inner edge 3 a of the magnet 3. The stopper 4a prevents the magnet 3 from falling off the rod 4.

  A mounting flange 4 b is provided at the upper end of the rod 4. The mounting flange 4b is formed in a disk shape having a diameter larger than the diameter of the opening 2a provided on the ceiling of the tank 2 in order to insert the liquid level detection device 1 into the tank 2, for example. The liquid level detecting device 1 is mounted on the tank 2 by the mounting flange 4b being fixedly mounted on the tank 2 so as to close the opening 2a of the tank 2.

  The rod 4 is inserted through the inner edge 3 a of the magnet 3. Thereby, the movement of the magnet 3 is guided by the rod 4 in a state where it floats on the liquid level of the liquid stored in the tank 2, and the stopper 4a and the mounting flange 4b as a movable range according to the liquid level. Is moved up and down.

  The plurality of magnetic intensity sensors S [1] to S [4] are composed of, for example, a Hall element or a magnetoresistive effect element, and output a voltage signal corresponding to the detected magnetic strength (intensity). The plurality of magnetic intensity sensors S [1] to S [4] output the same voltage signal for the same magnetic intensity. Each of the plurality of magnetic intensity sensors S [1] to S [4] is embedded in the rod 4, and is arranged so as to be sequentially arranged at intervals from above to below. The plurality of magnetic intensity sensors S [1] to S [4] are preferably arranged at equal intervals.

  The magnetic intensity sensor S [1] is disposed at a distance from the mounting flange 4b. Further, the magnetic intensity sensor S [4] is arranged with a gap from the stopper 4a.

  As shown in FIG. 5, the control unit 10 includes a difference value calculation unit 11 and a microcomputer 20 (hereinafter referred to as “μCOM 20”).

  The difference value calculation unit 11 includes a change-over switch 12 and a subtracter 13, and the difference value D [i] of output values of the magnetic intensity sensors S [1] to [4] arranged adjacent to each other. (I is a natural number from 1 to 3) is calculated.

  The change-over switch 12 is a two-circuit, three-contact switch (switch), and switches and connects three contacts provided corresponding to the two circuits at the same time. Magnetic intensity sensors S [1], S [2], and S [3] are connected to input terminals I11, I12, and I13 of the changeover switch 12. Input terminals I11, I12, and I13 are connected to an output terminal O1 serving as a first circuit by switch switching. Magnetic intensity sensors S [2], S [3], and S [4] are connected to input terminals I21, I22, and I23 of the changeover switch 12. The input terminals I21, I22, and I23 are connected to an output terminal O2 as a second circuit by switching a switch. Thereby, the changeover switch 12 (1) when the voltage signal of the magnetic intensity sensor S [1] is output from the output terminal O1, the voltage signal of the magnetic intensity sensor S [2] is output from the output terminal O2. (2) When the voltage signal of the magnetic intensity sensor S [2] is output from the output terminal O1, the voltage signal of the magnetic intensity sensor S [3] is output from the output terminal O2, and (3) the magnetism is output from the output terminal O1. When the voltage signal of the intensity sensor S [3] is output, the voltage signal of the magnetic intensity sensor S [4] is output from the output terminal O2. The control terminal Ic of the changeover switch 12 is connected to the μCOM 20, and the switch is switched according to a control signal from the μCOM 20.

  The subtractor 13 is composed of an operational amplifier, for example, and outputs a differential voltage signal obtained by subtracting the voltage signal input to the other input terminal from the voltage signal input to one input terminal. The output terminal O1 of the changeover switch 12 is connected to one input terminal of the subtractor 13, and the output terminal O2 of the changeover switch 12 is connected to the other input terminal, and output from the voltage signal of the output terminal O1. A differential voltage signal (that is, a differential value) obtained by subtracting the voltage signal of the terminal O2 is output from the output terminal.

  In the difference value calculation unit 11, each time the changeover switch of the changeover switch 12 is switched, (1) a difference voltage signal obtained by subtracting the voltage signal of the magnetic intensity sensor S [2] from the voltage signal of the magnetic intensity sensor S [1] ( That is, difference value D [1]), (2) difference voltage signal obtained by subtracting voltage signal of magnetic intensity sensor S [3] from voltage signal of magnetic intensity sensor S [2] (that is, difference value D [1]) (3) A differential voltage signal obtained by subtracting the voltage signal of the magnetic intensity sensor S [4] from the voltage signal of the magnetic intensity sensor S [3] (that is, the difference value D [3]) is output.

  The μCOM 20 includes a CPU, a ROM, a RAM, and the like, and controls the entire liquid level detection device 1. The ROM stores in advance a control program for causing the CPU to function as various means such as a liquid level detecting means, and the CPU functions as various means by executing the control program. Various parameters are stored in the ROM of the μCOM 20.

  The μCOM 20 further includes an external interface unit including an output port PO, an analog-digital conversion input port ADI, and a communication port (not shown) for communication with an external device. The control port Ic of the changeover switch 12 is connected to the output port PO, and the changeover switch 12 performs switch switching based on the control signal output from the output port PO. The analog-to-digital conversion input port ADI is connected to the difference value calculation unit 11 (specifically, the output of the subtractor 13), and the difference voltage signal output from the difference value calculation unit 11 is input thereto. And a numerical value corresponding to the signal, that is, a numerical value indicating the difference values D [1] to D [3] of the output values of the magnetic intensity sensors arranged adjacent to each other is passed to the CPU. Another electronic control unit or the like is connected to a communication port (not shown) via a wire harness (not shown), and a liquid level detection result is transmitted.

  In the ROM of the μCOM 20, the difference values D [1] to D [3] of the voltage signals (output values) of the magnetic intensity sensors arranged adjacent to each other and the position of the magnet 3 (that is, the liquid stored in the tank 2) High-precision liquid level detection reference information G [1] to G [3] and standard accuracy liquid level detection reference information H [1] to H [3] indicating the relationship with the liquid level) are stored in advance. .

  In the present embodiment, (1) the position of the magnet 3 and the difference value D in the range of the position of the magnet 3 where the difference value D [1] is [maximum value to 0 to minimum value], which is indicated by a thick solid line in FIG. High-accuracy liquid level detection reference information G [1] indicating the relationship with [1], (2) Magnet in the range of the position of the magnet 3 where the difference value D [2] is [maximum value to 0 to minimum value]. High-precision liquid level detection reference information G [2] indicating the relationship between the position 3 and the difference value D [2], and (3) a magnet in which the difference value D [3] is [maximum value to 0 to minimum value]. High-precision liquid level detection reference information G [3] indicating the relationship between the position of the magnet 3 in the range of position 3 and the difference value D [3] is stored in the ROM of the μCOM 20.

  Further, as shown in FIG. 6, the position of the magnet 3 is four sections T [1] at zero cross positions P [1] to P [3] where the difference values D [1] to D [3] are zero. ~ T [4]. In this embodiment, (1) standard accuracy liquid level detection reference information H indicating the relationship between the difference value D [1] in the section T [3] and the position of the magnet 3 indicated by a thick solid line in FIG. [1], (2) Standard accuracy liquid level detection reference information H [2], (3) indicating the relationship between the difference value D [2] in the sections T [1] and T [4] and the position of the magnet 3 Standard accuracy liquid level detection reference information H [3] indicating the relationship between the difference value D [3] in the section T [2] and the position of the magnet 3 is stored in the ROM of the μCOM 20.

  The high precision liquid level detection reference information G [1] to G [3] and the standard precision liquid level detection reference information H [1] to H [3] are stored in the form of, for example, a conversion table or a calculation formula. ing. The ROM of the μCOM 20 corresponds to information storage means.

  In the present embodiment, the high-accuracy liquid level detection reference information G [1] to G [3] has the difference values D [1] to D [3] of [maximum value to 0 to minimum value]. Although the entire range of the position of the magnet 3 is stored, the present invention is not limited to this. The high-accuracy liquid level detection reference information G [i] (i is a plurality of natural numbers from 1 to N−1) indicates that the difference value D [i] is [maximum value to 0 to minimum value] of the magnet 3. Of the range of positions, a range required in the liquid level detection process 1 described later may be stored. Further, the standard accuracy liquid level detection reference information H [1] to H [3] is stored only for the necessary section T, but is not limited thereto. The standard accuracy liquid level detection reference information H [i] is a liquid level detection described later in a range other than the range of the position of the magnet 3 where the difference value D [i] is [maximum value to 0 to minimum value]. What is necessary is just to memorize | store about the range required in the process 1. The high precision liquid level detection reference information G [i] and the standard precision liquid level detection reference information H [i] are stored for a range of magnet positions where the position of the magnet 3 is uniquely determined for the difference value D [i]. Yes. Further, all of the high precision liquid level detection reference information G [i] (G [1] to G [N-1]) and all of the standard precision liquid level detection reference information H [i] (H [1] to H [N-1]) need not be stored, and the information that is not used in the liquid level detection process may not be stored.

  Further, the ROM of the μCOM 20 stores high-precision liquid level detection reference information G [1] to G [3] and standard precision liquid level detection reference information H [1] to H [3] in detection of the liquid level. High-precision detection conditions for determining which one to use are stored in advance.

  In the present embodiment, the high accuracy detection condition is set as follows.

  That is, the high-precision detection condition in the section T [1] is that the difference value D [1] changes monotonically within the range from the maximum value to 0 to the minimum value, and the absolute slope of the change of the difference value D [1]. The range of the position of the magnet 3 is specified in which the value is larger than the absolute value of the gradient of change of the difference value D [2]. Specifically, in the section T [1], the high accuracy detection condition is that the value of the difference value D [2] when the magnet 3 is at a position where the difference value D [1] is the maximum value is w1. The high-precision detection condition is set such that the difference value D [2] is greater than or equal to a predetermined value W1 greater than the value w1 (difference value D [2] ≧ W1> w1).

  In addition, the high-precision detection condition in the section T [2] is that the difference value D [1] changes monotonically within the range of the maximum value to 0 to the minimum value, and the absolute slope of the change of the difference value D [1]. The range of the position of the magnet 3 is specified in which the value is larger than the absolute value of the gradient of change of the difference value D [3]. Specifically, in the section T [2], the high accuracy detection condition is that the value of the difference value D [3] when the magnet 3 is at a position where the difference value D [1] is the minimum value is w2. The high-precision detection condition is set such that the difference value D [3] is equal to or smaller than a predetermined value W2 that is smaller than the value w2 (difference value D [3] ≦ W2 <w2).

  Further, the high-precision detection condition in the section T [3] is that the difference value D [3] changes monotonically within the range of the maximum value to 0 to the minimum value, and the absolute slope of the change of the difference value D [3]. The range of the position of the magnet 3 is defined in which the value is larger than the absolute value of the gradient of change of the difference value D [1]. Specifically, in the section T [3], the high-precision detection condition is that the value of the difference value D [1] when the magnet 3 is at a position where the difference value D [3] is the maximum value is w5. At this time, the high-precision detection condition is set such that the difference value D [1] is greater than or equal to a predetermined value W5 greater than the value w5 (difference value D [1] ≧ W5> w5).

  In addition, the high-precision detection condition in the section T [4] is that the difference value D [3] changes monotonically within the range from the maximum value to 0 to the minimum value and the slope of the change of the difference value D [3] is absolute. The range of the position of the magnet 3 is specified in which the value is larger than the absolute value of the gradient of change of the difference value D [2]. Specifically, in the section T [4], the high-precision detection condition is that the value of the difference value D [2] when the magnet 3 is at a position where the difference value D [3] is the minimum value is w6. At this time, the high-precision detection condition is set such that the difference value D [2] is equal to or less than a predetermined value W6 smaller than the value w6 (difference value D [3] ≦ W6 <w6).

  That is, the high-accuracy detection condition is that the difference in which the position of the magnet 3 having the minimum value in the section T [j + 1] is present in the section T [j + 1] in the section T [j + 1] (j is one natural number from 1 to N−2). The value D [j] changes monotonically within the range of the maximum value to 0 to the minimum value, and the slope of the change of the difference value D [j] is the difference value D [a] (a is from 1 to N−1. The range of the position of the magnet 3 that is larger than the absolute value of the gradient of the change of one or more natural numbers other than j and j + 1) is defined. Alternatively, the high-precision detection condition is that, in the section T [j + 1], the difference value D [j + 1] in which the position of the magnet 3 having the maximum value in the section T [j + 1] is within the range of the maximum value to 0 to the minimum value. The range of the position of the magnet 3 is defined which changes monotonously and the slope of the change of the difference value D [j + 1] is larger than the absolute value of the slope of the change of the difference value D [a].

  Further, the high-precision detection condition is that, in the section T [1], the difference value D [1] in which the position of the magnet 3 having the maximum value in the section T [1] is within the range of the maximum value to 0 to the minimum value. The absolute value of the slope of change of the difference value D [b] (b is one or more natural numbers from 2 to N−1) that is monotonously changed and the slope of the change of the difference value D [1] is the absolute value. The range of the position of the magnet 3 that is larger than the value is defined.

  Further, the high-precision detection condition is that the difference value D [N−1] in which the position of the magnet 3 having the minimum value in the section T [N] is in the range T [N] is in the range from the maximum value to 0 to the minimum value. Change of the difference value D [N-1] is a change in the difference value D [c] (where c is a natural number of one or more of 1 to N-2). The range of the position of the magnet 3 that is larger than the absolute value of the inclination is defined.

  In this embodiment, the high-precision liquid level detection reference information G [1] to G [3], the standard precision liquid level detection reference information H [1] to H [3], and the high-precision detection condition are all Although stored in the ROM of one μCOM 20, the present invention is not limited to this, and each may be stored in separate storage means. In this case, a combination of the storage means corresponds to the information storage means.

  Next, an example of the process according to the present invention (liquid level detection process 1) executed by the CPU of the above-described μCOM 20 will be described with reference to the flowchart shown in FIG.

  The CPU of μCOM 20 advances the process to step S110 periodically (for example, every minute) in order to execute the liquid level detection process 1.

  In step S110, difference values D [1] to D [3] are acquired. Specifically, the CPU outputs a control signal from the output port PO and sequentially switches the changeover switch 12, thereby (1) the magnetic strength sensor S [1] from the output terminal O1 and the output terminal O2 of the changeover switch 12. Voltage signal of the magnetic strength sensor S [2], (2) voltage signal of the magnetic strength sensor S [2] and voltage signal of the magnetic strength sensor S [3], and (3) magnetic strength sensor S [3]. And the voltage signal of the magnetic intensity sensor S [4] are sequentially output. Thereby, the differential voltage signal of these voltage signals calculated in the subtractor 13 is input to the analog-digital conversion input port ADI, and the difference values D [1] to D [3] corresponding to the differential voltage signals are acquired. To do. Then, the process proceeds to step S120.

  In step S120, the CPU determines whether or not the sign of the difference value D [2] is positive. If the sign is positive, the process proceeds to step S130 (Y in S120), and if the sign is negative, step S140. (N in S120). In the present embodiment, when the difference value D [2] ≧ 0, the sign is determined to be positive, and when the difference value D [2] <0, the sign is determined to be negative. The same applies to the sign determination in the following steps. Alternatively, the sign may be determined to be positive when the difference value D [2]> 0, and the sign may be determined to be negative when the difference value D [2] ≦ 0.

  In step S130, the CPU determines whether or not the sign of the difference value D [1] is positive. If the sign is positive, it is determined that the position of the magnet 3 is in the section T [1], and the process proceeds to step S150. (Y in S130) If the sign is negative, it is assumed that the position of the magnet 3 is in the section T [2], and the process proceeds to step S180 (N in S130).

  In step S140, the CPU determines whether or not the sign of the difference value D [3] is positive. If the sign is positive, it is determined that the position of the magnet 3 is in the section T [3], and the process proceeds to step S210. (Y in S140) If the sign is negative, it is determined that the position of the magnet 3 is in the section T [4], and the process proceeds to step S240 (N in S140).

  In step S150, it is determined whether or not a high-precision detection condition is satisfied. Specifically, when the difference value D [2] is equal to or greater than the predetermined value W1, the CPU proceeds to step S160 as satisfying the high accuracy detection condition (Y in S150), and when the difference value D [2] is less than the predetermined value W1, Assuming that the accuracy detection condition is not satisfied, the process proceeds to step S170 (N in S150). Here, the predetermined value W1 is a value larger than the value w1 when the value of the difference value D [2] is w1 when the magnet 3 is at a position where the difference value D [1] is the maximum value. (That is, W1> w1). In this way, a margin is provided in the high-precision detection condition, and the absolute value of the change slope is excluded by excluding a relatively small portion of the absolute value of the change slope near the maximum value in the difference value D [1]. Only the part with the larger value can be used.

  In step S160, the CPU applies the difference value D [1] to the high-accuracy liquid level detection reference information G [1] to thereby position the magnet 3, that is, the liquid level of the liquid stored in the tank 2. Is detected. And the process of this flowchart is complete | finished.

  In step S170, the CPU applies the difference value D [2] to the standard precision liquid level detection reference information H [2] to thereby position the magnet 3, that is, the liquid level of the liquid stored in the tank 2. Is detected. And the process of this flowchart is complete | finished.

  In step S180, it is determined whether or not a high-precision detection condition is satisfied. Specifically, when the difference value D [3] is equal to or smaller than the predetermined value W2, the CPU proceeds to step S190 (Y in S180), assuming that the high-precision detection condition is satisfied. Assuming that the accuracy detection condition is not satisfied, the process proceeds to step S200 (N in S180). Here, the predetermined value W2 is a value smaller than the value w2 when the value of the difference value D [3] is w2 when the magnet 3 is at a position where the difference value D [1] is the minimum value. (That is, W2 <w2). In this way, a margin is provided in the high-precision detection condition, and the absolute value of the change slope is excluded by excluding a relatively small portion of the absolute value of the change slope near the minimum value in the difference value D [1]. Only the part with the larger value can be used.

  In step S190, the CPU applies the difference value D [1] to the high-accuracy liquid level detection reference information G [1] to thereby position the magnet 3, that is, the liquid level of the liquid stored in the tank 2. Is detected. And the process of this flowchart is complete | finished.

  In step S200, the CPU applies the difference value D [3] to the standard precision liquid level detection reference information H [3] to thereby position the magnet 3, that is, the liquid level of the liquid stored in the tank 2. Is detected. And the process of this flowchart is complete | finished.

  In step S210, it is determined whether or not a high-precision detection condition is satisfied. Specifically, when the difference value D [1] is equal to or greater than the predetermined value W5, the CPU proceeds to step S220 as satisfying the high accuracy detection condition (Y in S210), and when the difference value D [1] is less than the predetermined value W5 Assuming that the accuracy detection condition is not satisfied, the process proceeds to step S230 (N in S210). Here, the predetermined value W5 is a value larger than the value w5 when the value of the difference value D [1] is w5 when the magnet 3 is at a position where the difference value D [3] is the maximum value. (That is, W5> w5). In this way, a margin is provided for the high-precision detection condition, and the absolute value of the change gradient is excluded by excluding a relatively small portion of the absolute value of the change gradient near the maximum value in the difference value D [3]. Only the part with the larger value can be used.

  In step S220, the CPU applies the difference value D [3] to the high-accuracy liquid level detection reference information G [3] to thereby determine the position of the magnet 3, that is, the liquid level of the liquid stored in the tank 2. Is detected. And the process of this flowchart is complete | finished.

  In step S230, the CPU applies the difference value D [1] to the standard precision liquid level detection reference information H [1] to thereby position the magnet 3, that is, the liquid level of the liquid stored in the tank 2. Is detected. And the process of this flowchart is complete | finished.

  In step S240, it is determined whether or not a high-precision detection condition is satisfied. Specifically, when the difference value D [2] is equal to or smaller than the predetermined value W6, the CPU proceeds to step S250 as satisfying the high accuracy detection condition (Y in S240). Assuming that the accuracy detection condition is not satisfied, the process proceeds to step S260 (N in S240). Here, the predetermined value W6 is a value smaller than the value w6 when the value of the difference value D [2] is w6 when the magnet 3 is at a position where the difference value D [3] is the minimum value. (That is, W6 <w6). In this way, a margin is provided for the high-precision detection condition, and a relatively small portion of the absolute value of the change slope near the minimum value in the difference value D [3] is excluded, and the absolute value of the change slope is excluded. Only the part with the larger value can be used.

  In step S250, the CPU applies the difference value D [3] to the high-accuracy liquid level detection reference information G [3] to thereby position the magnet 3, that is, the liquid level of the liquid stored in the tank 2. Is detected. And the process of this flowchart is complete | finished.

  In step S260, the CPU applies the difference value D [2] to the standard precision liquid level detection reference information H [2] to thereby position the magnet 3, that is, the liquid level of the liquid stored in the tank 2. Is detected. And the process of this flowchart is complete | finished.

  Then, after completing the processing of this flowchart, the CPU transmits the detection result of the liquid level to another electronic control device or the like through the communication port. Then, display or recording of the liquid level is performed in another electronic control device or the like.

  In the present embodiment, the high-accuracy liquid level detection reference information G [2] is stored in the ROM as information, but is not used in the liquid level detection process 1 described above. Of course, a process using the high-accuracy liquid level detection reference information G [2] may be used.

  Next, an example of the operation in the control unit 10 of the liquid level detection device 1 described above will be described.

  The control unit 10 of the liquid level detecting device 1 acquires the difference values D [1] to D [3] of the magnetic intensity sensors that are periodically arranged adjacent to each other (S110).

  When it is determined that the sign of the difference value D [2] is positive (Y in S120) and the sign of the difference value D [1] is positive (Y in S130), the difference value D [1 ] Is positive, it is specified that the position of the magnet 3 is in the section T [1]. If the high-precision detection condition is satisfied in this state (difference value D [2] ≧ W1, Y in S150), the difference value D [1] having the maximum magnet position in this section T [1] and the high-precision liquid Based on the surface level detection reference information G [1], the liquid level corresponding to the position of the magnet 3 is detected (S160), and the high-precision detection condition is not satisfied (difference value D [2] <W1, S150 N) The liquid level corresponding to the position of the magnet 3 is detected based on the difference value D [2] monotonously changing in the section T [1] and the standard accuracy liquid level detection reference information H [2]. (S170).

  Alternatively, when it is determined that the sign of the difference value D [2] is positive (Y in S120) and the sign of the difference value D [1] is negative (N in S130), the difference value D [1 ] Is negative and the sign of the difference value D [2] is positive, it is specified that the position of the magnet 3 is in the section T [2]. If the high-precision detection condition is satisfied in this state (difference value D [3] ≦ W2, Y in S180), the difference value D [1] having the minimum magnet position in this section T [2] and the high-precision liquid Based on the surface level detection reference information G [1], the liquid level corresponding to the position of the magnet 3 is detected (S190), and the high-precision detection condition is not satisfied (difference value D [3]> W2, S180) N) The liquid level corresponding to the position of the magnet 3 is detected based on the difference value D [3] monotonously changing in the section T [2] and the standard accuracy liquid level detection reference information H [3]. (S200).

  Alternatively, when it is determined that the sign of the difference value D [2] is negative (N in S120) and the sign of the difference value D [3] is positive (Y in S140), D [2] Since the sign is negative and the sign of the difference value D [3] is positive, it is specified that the position of the magnet 3 is in the section T [3]. If the high-precision detection condition is satisfied in this state (difference value D [1] ≧ W5, Y in S210), the difference value D [3] having the maximum magnet position in this section T [3] and the high-precision liquid Based on the surface level detection reference information G [3], the liquid surface level corresponding to the position of the magnet 3 is detected (S220), and the high-precision detection condition is not satisfied (difference value D [1] <W5, S210 N) Based on the difference value D [1] monotonously changing in this section T [3] and the standard accuracy liquid level detection reference information H [1] corresponding to this difference value D [1], A liquid level corresponding to the position is detected (S230).

  Alternatively, when it is determined that the sign of the difference value D [2] is negative (N in S120) and the sign of the difference value D [3] is negative (N in S140), the difference value D [3 ] Is negative, it is specified that the position of the magnet 3 is in the section T [4]. When the high-precision detection condition is satisfied in this state (difference value D [2] ≦ W6, Y in S240), the difference value D [3] having a minimum magnet position in this section T [4] and the high-precision liquid Based on the surface level detection reference information G [3], the liquid level corresponding to the position of the magnet 3 is detected (S250), and the high-precision detection condition is not satisfied (difference value D [2]> W6, S240) N) Based on the difference value D [2] that changes monotonously in the section T [4] and the standard accuracy liquid level detection reference information H [2] corresponding to the difference value D [2], The liquid level according to the position is detected (S260).

  The liquid level detection device 1 according to the present embodiment includes a magnet 3 that is moved in the vertical direction according to the liquid level of the liquid stored in the tank 2, and a magnet 3 that is sequentially arranged at intervals in the vertical direction. Output values of a plurality of magnetic intensity sensors S [1] to S [4] that output a value corresponding to a distance from 3 and a magnetic intensity sensor S [i] (i is a plurality of natural numbers from 1 to 3). The difference value calculation unit 11 that calculates the difference value D [i] obtained by subtracting the output value of the magnetic intensity sensor S [i + 1] from the position of the magnet 3 where the difference value D [i] is maximum and the difference value D [i ] Is the liquid level level high-precision liquid level detection reference information G [i] indicating the relationship between the difference value D [i] and the liquid level in the range between the position 3 of the magnet and the difference value D [i]. ] Is the largest magnet position 3 and the difference value D [i] is the smallest. Of the μCOM 20 in which standard accuracy liquid level detection reference information H [i] indicating the relationship between the difference value D [i] and the liquid level in a part of the range other than the range between the position of the magnet 3 is stored. An information storage unit including a ROM and a liquid level detecting unit including a CPU of the μCOM 20, and the liquid level detecting unit includes (A) a difference value among the difference values D [1] to D [3]. When the sign of D [j] (j is 1 or 2) is negative and the sign of the difference value D [j + 1] of the difference values D [i] is positive, (Aα) the difference value D [ difference value D [a] other than j] and difference value D [j + 1] (a is a natural number of 1 other than j and j + 1 from 1 to 3) satisfies the predetermined high-precision detection condition, the difference value D [J] and high-accuracy liquid level detection reference information G [j] corresponding to the difference value D [j] or the difference The liquid level is detected based on the high-precision liquid level detection reference information G [j + 1] corresponding to the value D [j + 1] and the difference value D [j + 1], and (Aβ) the difference value D [a] is detected with high precision. When the condition is not satisfied, the liquid level is detected based on the difference value D [a] and the standard accuracy liquid level detection reference information H [a] corresponding to the difference value D [a], and (B) the difference value D When the sign of [1] is positive and (Bα) the difference value D [2] satisfies the high-precision detection condition, the high-precision liquid level corresponding to the difference value D [1] and the difference value D [1] When the liquid level is detected based on the detection reference information G [1] and the difference value D [2] does not satisfy the high-precision detection condition, the difference value D [2] and the difference value D [2] are detected. The liquid level is detected based on the corresponding standard accuracy liquid level detection reference information H [2], and (C) the difference value D [3] When the sign of (Cα) is the difference value D [2] satisfying the high-precision detection condition, the high-precision liquid level detection reference information corresponding to the difference value D [3] and the difference value D [3] When the liquid level is detected based on G [3] and (Cβ) difference value D [2] does not satisfy the high-precision detection condition, the standard corresponding to difference value D [2] and difference value D [2] The liquid level is detected based on the accurate liquid level detection reference information H [2].

  Further, the liquid level detecting means starts to determine the sign from the difference value D [2] selected from (A1) difference values D [1] to D [3], and (A2) difference value D [2]. ] Is determined to be positive toward the difference value D [1], the sign is determined to be positive at the end of the difference value D [2], and the difference value D [1] When (A2α) difference value D [3] satisfies the high-precision detection condition when the sign is first determined to be negative, the difference value D [1] and high-precision liquid level detection reference information G [1] And (A2β) when the difference value D [3] does not satisfy the high precision detection condition, the liquid level is detected based on the difference value D [3] and the standard precision liquid level detection reference information H [3]. When the liquid level is detected and (A3) the sign of the difference value D [2] is determined to be negative, the difference value D [3] (A3α) difference value D when the sign is determined to be negative in the difference value D [2] and the sign is finally determined to be positive in the difference value D [3]. When [1] satisfies the high-precision detection condition, the liquid level is detected based on the difference value D [3] and the high-precision liquid level detection reference information G [3], and (A3β) difference value D [1] When the high precision detection condition is not satisfied, the liquid level is detected based on the difference value D [1] and the standard precision liquid level detection reference information H [1].

  Further, the number N of the magnetic intensity sensors S [1] to S [4] is four, which is an even number, and the difference value D [M] for starting the sign determination among the difference values D [1] to D [3]. N / 2 = 2 (that is, the difference value D [2]) is selected in advance as the code determination start number M.

  Further, when the position of the magnet 3 is specified to be in the section T [1] or the section T [4], the difference value D [2] is used to determine the high-precision detection condition and the difference value D The liquid level is detected based on [2] and standard accuracy liquid level detection reference information H [2] corresponding to the difference value D [2].

  As described above, according to the present embodiment, when a predetermined high-precision detection condition is satisfied, the liquid level can be detected using a difference value having a larger rate of change with respect to a change in the position of the magnet 3. The liquid level can be accurately detected with a simple configuration using only one type of sensor.

  Further, the sign of one difference value D [2] (M = 2) selected from the plurality of difference values D [1] to D [3] is determined, and if the sign is positive, the difference value D Since the sign from [2] to the difference value D [3] is positive, the sign is determined toward the difference value D [1] opposite to the difference value D [3], or the sign is negative In this case, since the sign from the difference value D [2] to the difference value D [1] is negative, the sign determination is performed toward the difference value D [3] opposite to the difference value D [1]. By doing this, it is possible to specify a section where the magnet position is present by determining the codes for some of the difference values D without determining the codes for all of the plurality of difference values D [1] to D [3]. Therefore, the liquid level can be detected more quickly.

  In addition, the number N of the magnetic intensity sensors S [1] to S [4] is four, which is an even number, and the difference value D [for starting the code determination among the plurality of difference values D [1] to D [3]. Since 4/2 = 2 is selected in advance as the code determination start number M of M], for example, the code is determined from the ends of the plurality of difference values D (difference value D [1] or difference value D [3]). The maximum number of code determinations can be reduced as compared with the case where the liquid level is started, so that the liquid level can be detected faster.

  Further, when the position of the magnet 3 is specified to be in the section T [1] or the section T [4], the difference value D [2] is used to determine the high-precision detection condition and the difference value D Since the liquid level is detected on the basis of [2] and the standard accuracy liquid level detection reference information H [2] corresponding to the difference value D [2], the section T [2 next to the section T [1] is detected. ] Has the maximum value of the difference value D [2], and the section T [3] immediately adjacent to the section T [4] has the minimum value of the difference value D [2]. In T [1], the difference value D [2] has the largest absolute value of the change slope, and in the interval T [4], the difference value D [2] has the largest absolute value of the slope of change. In the sections T [1] and T [4] that are identified as having the position of the magnet 3, the absolute value of the gradient of change is the largest. Can determine and liquid level detection of high accuracy detection conditions using a hearing difference value D [2], it is possible to improve the detection accuracy.

  In the present embodiment described above, in the section T [2], when the difference value D [3] is equal to or less than the predetermined value W2, the high-precision detection condition is satisfied, and the difference value D [1] and the high-precision liquid level detection reference information Although the liquid level is detected based on G [1], the present invention is not limited to this. For example, in the section T [2], when the value of the difference value D [3] when the magnet 3 is at the position where the difference value D [2] is the maximum value is w3, the same as the section T [1]. If the difference value D [3] is equal to or greater than a predetermined value W3 that is greater than the value w3, the liquid level is detected based on the difference value D [2] and the high-precision liquid level detection reference information G [2]. You may do it. In this case, the high-precision detection condition is that the difference value D [3] is equal to or greater than the predetermined value W3.

  Similarly, in the section T [3], when the value of the difference value D [1] when the magnet 3 is at a position where the difference value D [2] is the minimum value is w4, the section T [4] ] If the difference value D [1] is equal to or smaller than a predetermined value W4 smaller than this value w4, the liquid level is determined based on the difference value D [2] and the high-precision liquid level detection reference information G [2]. May be detected. In this case, the high-precision detection condition is that the difference value D [1] is equal to or less than the predetermined value W4.

  Further, in the present embodiment, in each of the sections T [1] to T [4], the high-precision detection condition is determined using the 1 difference value D, and the 1 difference value D and the difference value D are supported. Although the liquid level is detected based on the standard accuracy liquid level detection reference information H, the present invention is not limited to this.

  For example, in the present embodiment, the difference values D [2] and D [3] monotonously change in the section T [1], and thus the difference values D [2] and D [3] in the section T [1]. ] Is prepared, and when one of the difference values D [2] and D [3] satisfies the high-precision detection preliminary condition, or both satisfy the high-precision detection preliminary condition In some cases, the processing may be performed assuming that the high-precision detection condition is satisfied.

  Also, standard accuracy liquid level detection reference information H [2] and H [3] corresponding to the difference values D [2] and D [3] are prepared in the section T [1], and the position of the magnet 3 is set to the section T [1]. When the high-precision detection condition is not satisfied when it is specified as T [1], the standard value liquid level level detection reference information H [2] corresponding to the difference value D [2] and the difference value D [2] is obtained. The first preliminary liquid level is detected based on the difference value D [3] and the standard accuracy liquid level detection reference information H [3] corresponding to the difference value D [3]. The preliminary liquid level may be detected, and the average value of the first and second preliminary liquid levels may be detected as the liquid level. The same applies to the section T [4]. That is, the high accuracy detection condition may be determined based on the plurality of difference values D, and the liquid level is detected based on the plurality of difference values D and the plurality of standard accuracy liquid level detection reference information H. May be. Alternatively, in the section T [1] and the section T [4], instead of the difference value D [2], the difference value D [3] (section T [1]) and the difference value D [1 that monotonously change in the section. ] (Section T [4]), the high-precision detection condition may be determined, or the liquid level may be detected.

  In the present embodiment, the configuration includes four magnetic intensity sensors S [1] to S [4]. However, the present invention is not limited to this. For example, five or six magnetic intensity sensors are provided. Etc., or a configuration including four or more magnetic intensity sensors S [1] to S [N] (N is an even number of 4 or more). Even in such a configuration, the liquid level can be detected in the same manner as the liquid level detecting apparatus 1 described above.

  For example, five magnetic intensity sensors S [1] to S [5] are embedded in the rod 4 and arranged so as to be sequentially arranged at intervals from above to below, and the changeover switch of the difference value calculation unit 11 The configuration in which 12 is a two-circuit four-contact is the same as that of the liquid level detecting device 1 described above. FIG. 8 shows the position of a magnet and a plurality of difference values D [1] to D [4] and high-precision liquid level detection reference information G [1] to G in a liquid level detection apparatus having five magnetic intensity sensors. An example of the graph which shows a relationship with [4] and standard precision liquid level detection reference information H [1] -H [4] is shown. FIG. 10 and FIG. 11 are flowcharts showing an example of the process (liquid level detection process 1a) according to the present invention which is executed by the CPU of the microcomputer provided in the control unit of the liquid level detection apparatus having five magnetic intensity sensors. , And the subsequent flowchart.

  Alternatively, for example, six magnetic intensity sensors S [1] to S [6] are embedded in the rod 4 and arranged so as to be sequentially arranged at intervals from above to below the difference value calculation unit 11. The configuration in which the changeover switch 12 has two circuits and five contacts is the same as that of the liquid level detection device 1 described above. FIG. 11 shows the position of a magnet and a plurality of difference values D [1] to D [5] and high-precision liquid level detection reference information G [1] to G in a liquid level detection apparatus having six magnetic intensity sensors. FIG. 12 and FIG. 13 show an example of a graph showing the relationship between [5] and standard accuracy liquid level detection reference information H [1] to H [5], and FIG. 12 and FIG. 13 show the liquid level provided with six magnetic intensity sensors. The flowchart which shows an example of the process (liquid level detection process 1b) which concerns on this invention which CPU of the microcomputer with which the control part of a detection apparatus is provided performs the following flowchart.

(Second Embodiment)
Below, the liquid level detection apparatus of the 2nd Embodiment of this invention is demonstrated with reference to FIGS.

  FIG. 14 is a schematic configuration diagram of a liquid level detecting device according to the second embodiment of the present invention. FIG. 15 shows the position of a magnet and a plurality of difference values D [1] to D [3] and high-accuracy liquid level detection reference information G [1] to G [1] in the liquid level detection apparatus of the second embodiment of the present invention. It is an example of the graph which shows the relationship between G [3] and standard precision liquid level detection reference information H [1], H [3]. FIG. 16 is a flowchart illustrating an example of a process (liquid level detection process 2) according to the present invention which is executed by the CPU of the microcomputer provided in the control unit of the liquid level detection apparatus of the second embodiment.

  The liquid level detection apparatus 1A of the present embodiment is different from the liquid level detection apparatus 1 of the first embodiment described above in that the arrangement of the magnetic intensity sensors S [1] to S [4] is different and the control unit 10 The configuration is the same except that the liquid level detection process 2 shown in FIG. 15 is executed instead of the liquid level detection process 1. For this reason, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 14, in the liquid level detection device 1A, the magnetic intensity sensor S [1] is disposed immediately below the mounting flange 4b. As a result, the output value of the magnetic intensity sensor S [1] becomes maximum when the position of the magnet 3 is the upper end in the movable range. Further, the magnetic intensity sensor S [4] is disposed immediately above the stopper 4a. As a result, the output value of the magnetic intensity sensor S [4] becomes maximum when the position of the magnet 3 is the lower end in the movable range.

  In the ROM of the μCOM 20, the difference values D [1] to D [3] of the voltage signals (output values) of the magnetic intensity sensors arranged adjacent to each other and the position of the magnet 3 (that is, the liquid stored in the tank 2) High-precision liquid level detection reference information G [1] to G [3] and standard precision liquid level detection reference information H [1], H [3] indicating the relationship with the liquid level) are stored in advance. .

  In the present embodiment, (1) the position of the magnet 3 and the difference value D in the range of the position of the magnet 3 where the difference value D [1] is [maximum value to 0 to minimum value], which is indicated by a thick solid line in FIG. High-accuracy liquid level detection reference information G [1] indicating the relationship with [1], (2) Magnet in the range of the position of the magnet 3 where the difference value D [2] is [maximum value to 0 to minimum value]. High-precision liquid level detection reference information G [2] indicating the relationship between the position 3 and the difference value D [2], and (3) a magnet in which the difference value D [3] is [maximum value to 0 to minimum value]. High-precision liquid level detection reference information G [3] indicating the relationship between the position of the magnet 3 in the range of position 3 and the difference value D [3] is stored in the ROM of the μCOM 20.

  As shown in FIG. 15, the position of the magnet 3 is four sections T [1] at zero cross positions P [1] to P [3] where the difference values D [1] to D [3] are zero. ~ T [4]. In the present embodiment, standard accuracy liquid level detection reference information H indicating the relationship between the difference value D [1] in the section T [3] and the position of the magnet 3 indicated by a thick solid line in FIG. [1], (2) Standard accuracy liquid level detection reference information H [3] indicating the relationship between the difference value D [3] in the section T [2] and the position of the magnet 3 is stored in the ROM of the μCOM 20. Yes.

  Further, in the ROM of the μCOM 20, as in the first embodiment, high-precision liquid level detection reference information G [1], G [3] and standard precision liquid level detection reference information H in the detection of the liquid level. High-precision detection conditions for determining whether to use [1] or H [3] are stored in advance.

  In the present embodiment, since the magnetic intensity sensor S [1] is disposed immediately below the mounting flange 4b, the magnetic intensity sensor S [1] is output when the position of the magnet 3 is the upper end in the movable range. The value is the maximum. Thereby, in the section T [1], the difference value D [1] changes monotonously (monotonically decreases) as the position of the magnet 3 moves from the upper end in the movable range to the zero cross position P [1].

  Further, since the magnetic strength sensor S [4] is disposed immediately above the stopper 4a, the magnetic strength sensor S [4] has a maximum output value when the position of the magnet 3 is the lower end in the movable range. Become. Thereby, in the section T [4], the difference value D [3] monotonously changes (monotonically decreases) as the position of the magnet 3 moves from the zero cross position P [3] to the lower end in the movable range.

  Therefore, in the present embodiment, in the section T [1] and the section T [4], the difference value D [1] monotonically changing in each section and the high-precision liquid level detection reference information G [1], In addition, the liquid level is detected using the difference value D [3] and the high-precision liquid level detection reference information G [3].

  Next, an example of the process (liquid level detection process 2) according to the present invention executed by the CPU of the μCOM 20 included in the control unit 10 will be described below with reference to the flowchart shown in FIG.

  The CPU of the μCOM 20 advances the process to step T110 periodically (for example, every minute) in order to execute the liquid level detection process.

  Steps T110, T120, T160, T180 to T230, and T250 execute the same processing as Steps S110, S120, S160, S180 to S230, and S250 of the first embodiment described above. Will be described.

  In step T130, the CPU determines whether or not the sign of the difference value D [1] is positive. If the sign is positive, it is determined that the position of the magnet 3 is in the section T [1], and the process proceeds to step T160. (Y in T130) If the sign is negative, it is determined that the position of the magnet 3 is in the section T [2], and the process proceeds to Step T180 (N in T130). That is, when it is specified that the position of the magnet 3 is in the section T [1], the process proceeds to processing for detecting the liquid level without determining the high-precision detection condition.

  In step T140, the CPU determines whether or not the sign of the difference value D [3] is positive. If the sign is positive, it is determined that the position of the magnet 3 is in the section T [3], and the process proceeds to step T210. (Y in T140) If the sign is negative, it is determined that the position of the magnet 3 is in the section T [4], and the process proceeds to Step T250 (N in T140). That is, when it is specified that the position of the magnet 3 is in the section T [4], the process proceeds to processing for detecting the liquid level without determining the high-precision detection condition.

  Then, after completing the processing of this flowchart, the CPU transmits the detection result of the liquid level to another electronic control device or the like through the communication port. Then, display or recording of the liquid level is performed in another electronic control device or the like.

  Next, an example of the operation in the control unit 10 of the liquid level detection device 1A described above will be described.

  The control unit 10 of the liquid level detection device 1A acquires the difference values D [1] to D [3] of the magnetic intensity sensors periodically arranged adjacent to each other (T110).

  When it is determined that the sign of the difference value D [2] is positive (Y in T120) and the sign of the difference value D [1] is positive (Y in T130), the difference value D [1 ] Is positive, it is specified that the position of the magnet 3 is in the section T [1]. At this time, the liquid level corresponding to the position of the magnet 3 based on the difference value D [1] having a maximum magnet position in the section T [1] and the high-accuracy liquid level detection reference information G [1]. The level is detected (T160).

  Alternatively, when it is determined that the sign of the difference value D [2] is positive (Y in T120) and the sign of the difference value D [1] is negative (N in T130), the difference value D [1 ] Is negative and the sign of the difference value D [2] is positive, it is specified that the position of the magnet 3 is in the section T [2]. When the high-precision detection condition is satisfied in this state (difference value D [3] ≦ W2, T180 is Y), the difference value D [1] having a minimum magnet position in this section T [2] and the high-precision liquid Based on the surface level detection reference information G [1], the liquid level corresponding to the position of the magnet 3 is detected (T190), and the high-precision detection condition is not satisfied (difference value D [3]> W2, T180 N) The liquid level corresponding to the position of the magnet 3 is detected based on the difference value D [3] monotonously changing in the section T [2] and the standard accuracy liquid level detection reference information H [3]. (T200).

  Alternatively, when it is determined that the sign of the difference value D [2] is negative (N in T120) and the sign of the difference value D [3] is positive (Y in T140), D [2] Since the sign is negative and the sign of the difference value D [3] is positive, it is specified that the position of the magnet 3 is in the section T [3]. If the high-precision detection condition is satisfied in this state (difference value D [1] ≧ W5, Y at T210), the difference value D [3] having the maximum magnet position in this section T [3] and the high-precision liquid Based on the surface level detection reference information G [3], the liquid level corresponding to the position of the magnet 3 is detected (T220), and the high-precision detection condition is not satisfied (difference value D [1] <W5, T210 N) Based on the difference value D [1] monotonously changing in this section T [3] and the standard accuracy liquid level detection reference information H [1] corresponding to this difference value D [1], A liquid level corresponding to the position is detected (T230).

  Alternatively, when it is determined that the sign of the difference value D [2] is negative (N in T120) and the sign of the difference value D [3] is negative (N in T140), the difference value D [3 ] Is negative, it is specified that the position of the magnet 3 is in the section T [4]. At this time, the liquid level corresponding to the position of the magnet 3 based on the difference value D [3] having a minimum magnet position in the section T [4] and the high-accuracy liquid level detection reference information G [3]. The level is detected (T250).

  The liquid level detecting device 1A of the present embodiment includes a magnet 3 that is moved in the vertical direction according to the liquid level of the liquid stored in the tank 2, and a magnet that is sequentially arranged with a gap in the vertical direction. Output of a plurality of magnetic intensity sensors S [1] to S [4] that output a value corresponding to a distance from 3 and the magnetic intensity sensor S [i] (i is a plurality of natural numbers from 1 to 3). A difference value calculation unit 11 for calculating a difference value D [i] obtained by subtracting the output value of the magnetic intensity sensor S [i + 1] from the value; a position of the magnet 3 where the difference value D [i] is maximum; and a difference value D High-precision liquid level detection reference information G [i] indicating the relationship between the difference value D [i] and the liquid level in the range between the position of the magnet 3 where [i] is minimum, and the difference value D The position of the magnet 3 where [i] is maximum and the difference value D [ ] Is stored in the standard accuracy liquid level detection reference information H [i] indicating the relationship between the difference value D [i] and the liquid level in a range other than the range between the position of the magnet 3 where the Information storage means comprising a ROM and liquid level detection means comprising a CPU of μCOM 20, and the magnetic intensity sensor S [1] is output when the position of the magnet 3 is at the upper end in its movable range. The magnetic level sensor S [4] is arranged to maximize the output value, and the magnetic level sensor S [4] is arranged to maximize the output value when the position of the magnet 3 is at the lower end in the movable range. (A) The difference value D [j] (j is 1 or 2) among the difference values D [1] to D [3] is negative, and the difference values D [1] to D [ 3] has a positive sign of the difference value D [j + 1] The difference value D [a] other than (Aα) difference value D [j] and the difference value D [j + 1] (a is one or a plurality of natural numbers other than j and j + 1 from 1 to 3). When a predetermined high-precision detection condition is satisfied, high-precision liquid level detection reference information G [j] corresponding to the difference value D [j] and the difference value D [j], or the difference value D [j + 1] and the difference value When the liquid level is detected based on the high-accuracy liquid level detection reference information G [j + 1] corresponding to D [j + 1] and (Aβ) the difference value D [a] does not satisfy the high-precision detection condition, the difference The liquid level is detected based on the standard precision liquid level detection reference information H [a] corresponding to the value D [a] and the difference value D [a], and (B ′) the sign of the difference value D [1] is When positive, the differential value D [1] and the high-precision liquid level detection reference information G [corresponding to the differential value D [1] The liquid level is detected based on the difference value D [3] and the difference level D [3] is negative when the sign of the difference value D [3] is negative. The liquid level is detected based on the detection reference information G [3].

  Further, the liquid level detecting means starts to determine the sign from the difference value D [2] selected from (A1) difference values D [1] to D [3], and (A2) difference value D [2]. ] Is determined to be positive toward the difference value D [1], the sign is determined to be positive at the end of the difference value D [2], and the difference value D [1] When (A2α) difference value D [3] satisfies the high-precision detection condition when the sign is first determined to be negative, the difference value D [1] and high-precision liquid level detection reference information G [1] And (A2β) when the difference value D [3] does not satisfy the high precision detection condition, the liquid level is detected based on the difference value D [3] and the standard precision liquid level detection reference information H [3]. When the liquid level is detected and (A3) the sign of the difference value D [2] is determined to be negative, the difference value D [3] (A3α) difference value D when the sign is determined to be negative in the difference value D [2] and the sign is finally determined to be positive in the difference value D [3]. When [1] satisfies the high-precision detection condition, the liquid level is detected based on the difference value D [3] and the high-precision liquid level detection reference information G [3], and (A3β) difference value D [1] When the high precision detection condition is not satisfied, the liquid level is detected based on the difference value D [1] and the standard precision liquid level detection reference information H [1].

  Further, the number N of the magnetic intensity sensors S [1] to S [4] is four, which is an even number, and the difference value D [M] for starting the sign determination among the difference values D [1] to D [3]. N / 2 = 2 (that is, the difference value D [2]) is selected in advance as the code determination start number M.

  As described above, according to the present embodiment, similarly to the first embodiment described above, when a predetermined high-precision detection condition is satisfied, the liquid level is determined using a difference value having a larger rate of change with respect to a change in the magnet position. Therefore, the liquid level can be accurately detected with a simple configuration using only one type of sensor. Further, in the section T [1] on the magnetic strength sensor S [1] side from the zero cross position P [1], the difference value D [1] monotonously toward the maximum value as the distance from the zero cross position P [1] increases. In addition, in the section T [4] on the side of the magnetic intensity sensor S [4] from the zero cross position P [3], the difference value D [3] tends to the minimum value as the distance from the zero cross position P [3] increases. Therefore, in these sections, the magnet position (that is, the liquid level) is uniquely determined with respect to the difference value D [1] or the difference value D [3], and the difference value D [1] or the difference value is determined. The liquid level can be detected based on D [3]. Furthermore, in these sections T [1] or T [4], the difference value D [1] or the difference value D [3] changes monotonically from 0 to the maximum value or from 0 to the minimum value. The absolute value of the inclination is large, so that the liquid level can be detected with high accuracy.

  Further, the sign of one difference value D [2] (M = 2) selected from the plurality of difference values D [1] to D [3] is determined, and if the sign is positive, the difference value D Since the sign from [2] to the difference value D [3] is positive, the sign is determined toward the difference value D [1] opposite to the difference value D [3], or the sign is negative In this case, since the sign from the difference value D [2] to the difference value D [1] is negative, the sign determination is performed toward the difference value D [3] opposite to the difference value D [1]. By doing this, it is possible to specify a section where the magnet position is present by determining the codes for some of the difference values D without determining the codes for all of the plurality of difference values D [1] to D [3]. Therefore, the liquid level can be detected more quickly.

  In addition, the number N of the magnetic intensity sensors S [1] to S [4] is four, which is an even number, and the difference value D [for starting the code determination among the plurality of difference values D [1] to D [3]. Since 4/2 = 2 is selected in advance as the code determination start number M of M], for example, the code is determined from the ends of the plurality of difference values D (difference value D [1] or difference value D [3]). The maximum number of code determinations can be reduced as compared with the case where the liquid level is started, so that the liquid level can be detected faster.

  In the present embodiment, the configuration includes four magnetic intensity sensors S [1] to S [4]. However, the present invention is not limited to this. For example, five or six magnetic intensity sensors are provided. Etc., or a configuration including four or more magnetic intensity sensors S [1] to S [N] (N is an even number of 4 or more). Even with such a configuration, the liquid level can be detected in the same manner as the liquid level detection apparatus 1A described above.

  For example, five magnetic intensity sensors S [1] to S [5] are embedded in the rod 4 and arranged so as to be sequentially arranged at intervals from above to below, and the changeover switch of the difference value calculation unit 11 The configuration in which 12 is a two-circuit four-contact is the same as that of the liquid level detecting device 1A. FIG. 17 shows the position of a magnet and a plurality of difference values D [1] to D [4] and high-accuracy liquid level detection reference information G [1] to G in a liquid level detection apparatus having five magnetic intensity sensors. An example of the graph which shows a relationship with [4] and standard precision liquid level detection reference information H [1] -H [4] is shown. FIG. 18 and FIG. 19 are flowcharts showing an example of the process (liquid level detection process 2a) according to the present invention executed by the CPU of the microcomputer provided in the control unit of the liquid level detection apparatus having five magnetic intensity sensors. , And the subsequent flowchart.

  Alternatively, for example, six magnetic intensity sensors S [1] to S [6] are embedded in the rod 4 and arranged so as to be sequentially arranged at intervals from above to below the difference value calculation unit 11. The configuration in which the changeover switch 12 has two circuits and five contacts is the same as that of the liquid level detection device 1A. FIG. 20 shows the position of a magnet and a plurality of difference values D [1] to D [5] and high-accuracy liquid level detection reference information G [1] to G in a liquid level detection apparatus having six magnetic intensity sensors. FIG. 21 and FIG. 22 show an example of a graph showing the relationship between [5] and standard accuracy liquid level detection reference information H [1] to H [5]. FIG. 21 and FIG. The flowchart which shows an example of the process (liquid level detection process 2b) which concerns on this invention which CPU of the microcomputer with which the control part of a detection apparatus is provided performs, and the subsequent flowchart are shown.

  In the present embodiment, the configuration includes four magnetic intensity sensors S [1] to S [4]. However, the present invention is not limited to this. For example, five or six magnetic intensity sensors are provided. Etc., or a configuration including four or more magnetic intensity sensors S [1] to S [N] (N is an even number of 4 or more). Even with such a configuration, the liquid level can be detected in the same manner as the liquid level detection apparatus 1A described above.

  For example, the configuration includes five magnetic intensity sensors S [1] to S [5], each of which is embedded in the rod 4, and is arranged so as to be sequentially arranged at intervals from above to below. Then, the configuration of the changeover switch 12 of the difference value calculation unit 11 is changed to two circuits and four contacts. FIG. 15 shows the position of a magnet and a plurality of difference values D [1] to D [4] and high-precision liquid level detection reference information G [1] to G in a liquid level detection device having five magnetic intensity sensors. An example of the graph which shows a relationship with [4] and standard precision liquid level detection reference information H [1] -H [4] is shown. FIG. 16 is a flowchart showing an example of the process (liquid level detection process 2a) according to the present invention which is executed by the CPU of the microcomputer provided in the control unit of the liquid level detection apparatus including five magnetic intensity sensors.

  Further, for example, six magnetic intensity sensors S [1] to S [6] are provided, each embedded in the rod 4, and arranged so as to be sequentially arranged at intervals from above to below. In the configuration, the configuration of the changeover switch 12 of the difference value calculation unit 11 is changed to two circuits and five contacts. FIG. 17 shows the position of a magnet and a plurality of difference values D [1] to D [5] and high-accuracy liquid level detection reference information G [1] to G in a liquid level detection apparatus having six magnetic intensity sensors. FIG. 18 shows an example of a graph showing the relationship between [5] and standard accuracy liquid level detection reference information H [1] to H [5], and FIG. 18 shows a liquid level detection apparatus having six magnetic intensity sensors. The flowchart which shows an example of the process (liquid level detection process 2b) which concerns on this invention which CPU of the microcomputer with which a control part is provided performs this invention is shown.

  In the first embodiment and the second embodiment described above, in the liquid level detection process 1 and the liquid level detection process 2, the difference value D [2] for starting the code determination is selected in advance. However, the present invention is not limited to this. For example, the next liquid level from the difference value D [k] (k is a natural number of 1 from 1 to 3) for which the sign is finally determined among the plurality of difference values D [1] to D [3]. Select k as the code determination start number M of the difference value D [M] for starting the code determination among the plurality of difference values D [1] to D [3] so as to start the code determination in the level detection You may make it do. The fact that the sign is finally determined for the difference value D [k] means that the interval T defined by the zero cross position P [k] of the difference value D [k] (that is, the right or left interval of P [k]). T) means that the position of the magnet 3 is present.

  For example, when the sign is finally determined for the difference value D [1] in the current liquid level detection, the sign determination is started from the difference value D [1] in the next detection, and (1) the difference value D When it is determined that the sign of [1] is positive, all the signs of the difference values D [1] to D [3] are positive, and it is specified that the position of the magnet 3 is in the section T [1]. (2) When it is determined that the sign of the difference value D [1] is negative and the sign of the difference value D [2] is positive, the sign of the difference value D [1] is negative and the difference The signs of the values D [2] and D [3] are positive, and it is specified that the position of the magnet 3 is in the section T [2]. (3) The sign of the difference values D [1] and D [2] Is negative and the sign of the difference value D [3] is determined to be positive, the position of the magnet 3 may be in the section T [3]. Is constant, (4) All the sign of the difference value D [1] ~D [3] is when it is determined to be negative, the position of the magnet 3, it is specified that in the interval T [4].

  Therefore, if the position of the magnet 3 is in the section T [1] or T [2] defined by the zero cross position P [1] of the difference value D [1], the magnet 3 can be determined once or twice. It is possible to identify the section where the position is. Further, when the sign is finally determined for the difference value D [3] in the current liquid level detection, the sign determination is also performed when the sign determination is started from the difference value D [3] in the next detection. It is the same except that it advances in the reverse direction.

  Therefore, in the next detection, the difference value D [k] (k is a natural number of 1 out of 1 to 3) in which the sign is determined lastly among the plurality of difference values D [1] to D [3]. If k is selected as the code determination start number M of the difference value D [M] for starting the code determination among the difference values D [1] to D [3] so as to start the code determination, For the difference value D [k] for which the sign is finally determined in the detection of the liquid level, the determination of the sign is started in the next detection of the liquid level. Since (liquid) does not decrease, there is a high possibility that there is a magnet position in the vicinity of the zero cross position P [k] defined by the difference value D [k]. Therefore, from this difference value D [k] By starting the sign determination, Level detection can be performed more quickly.

  In the first embodiment and the second embodiment described above, when the difference value D [2] (2 = N / 2) is 0, the sign of the difference value D [2] is positive and the process proceeds. Yes, when the difference value D [2] is 0, the position of the magnet 3 is considered to be at the middle point (or the vicinity thereof) of the movable range. However, depending on the performance and arrangement of the magnetic intensity sensors S [1] to S [N], the difference value D [N / 2] becomes 0 even when the position of the magnet 3 is near both ends of the movable range. It may become. Therefore, in such a configuration, when the difference value D [N / 2] is 0, the difference value D [(N / 2) −1] and the difference value D [(N / 2) +1] on both sides thereof are The accuracy of the liquid level can be further improved by determining the sign of the value obtained by adding the values and proceeding with the determined sign as the sign of the difference value D [N / 2].

  Further, in the first embodiment and the second embodiment described above, the difference value calculation unit 11 as the difference value calculation means is configured by the changeover switch 12 and the subtractor 13. It is not limited. For example, the μCOM 20 is provided with a plurality of analog-digital conversion input ports ADI, and the magnetic intensity sensors S [1] to S [4] are connected to the plurality of input ports ADI to thereby generate the magnetic intensity sensor S [1]. It is good also as a structure which takes in the output of -S [4] into CPU, and calculates a difference value in CPU. In the case of this configuration, the CPU of the μCOM 20 functions as a difference value calculation unit.

  In addition, embodiment mentioned above only showed the typical form of this invention, and this invention is not limited to embodiment. That is, various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1, 1A Liquid level detection apparatus 2 Tank 3 Magnet 4 Rod 10 Control part 11 Difference value calculation part (difference value calculation means)
12 changeover switch 13 subtractor 20 microcomputer (liquid level detection means, information storage means)
S Magnetic strength sensor D Difference value G High-precision liquid level detection reference information H Standard-precision liquid level detection reference information

Claims (6)

A magnet that moves up and down according to the liquid level of the liquid stored in the tank;
A plurality of magnetic intensity sensors S [1] to S [N] (N is a natural number of 4 or more), which are sequentially arranged in the vertical direction and spaced from each other and output a value corresponding to the distance from the magnet;
A difference value D [i] is calculated by subtracting the output value of the magnetic intensity sensor S [i + 1] from the output value of the magnetic intensity sensor S [i] (i is a plurality of natural numbers from 1 to N-1). Difference value calculating means;
The difference value D [i] in part or all of the range between the position of the magnet where the difference value D [i] is maximum and the position of the magnet where the difference value D [i] is minimum High-precision liquid level detection reference information G [i] indicating the relationship with the liquid level, the position of the magnet at which the difference value D [i] is maximized, and the difference value D [i] is minimized. Standard accuracy liquid level detection reference information H [i] indicating the relationship between the difference value D [i] and the liquid level in part or all of the range other than the range between the magnet position, and a predetermined value Information storage means in which the high-precision detection conditions are stored;
Liquid level detection means,
The liquid level detection means
(A) The difference value D [j] (j is a natural number of 1 from 1 to N−2) of the difference values D [i] is negative, and the difference value D [i ], The sign of the difference value D [j + 1] is positive,
(Aα) The difference value D [a] other than the difference value D [j] and the difference value D [j + 1] (a is one or a plurality of natural numbers other than j and j + 1 from 1 to N−1). When the high-precision detection condition is satisfied, the high-precision liquid level detection reference information G [j] corresponding to the difference value D [j] and the difference value D [j], or the difference value D [j + 1] and Detecting the liquid level based on high-precision liquid level detection reference information G [j + 1] corresponding to the difference value D [j + 1],
(Aβ) When the difference value D [a] does not satisfy the high-precision detection condition, standard accuracy liquid level detection reference information H [a corresponding to the difference value D [a] and the difference value D [a] ] To detect the liquid level based on
(B) When the sign of the difference value D [1] of the difference values D [i] is positive,
(Bα) When a difference value D [b] other than the difference value D [1] (b is one or more natural numbers from 2 to N−1) satisfies the high-precision detection condition, the difference value Detecting the liquid level based on high-precision liquid level detection reference information G [1] corresponding to D [1] and the difference value D [1],
(Bβ) When the difference value D [b] does not satisfy the high-precision detection condition, standard accuracy liquid level detection reference information H [b corresponding to the difference value D [b] and the difference value D [b] ] To detect the liquid level based on
(C) When the sign of the difference value D [N−1] of the difference values D [i] is negative,
(Cα) When a difference value D [c] other than the difference value D [N−1] (c is one or more natural numbers from 1 to N−2) satisfies the high-precision detection condition, The liquid level is detected based on a difference value D [N-1] and high-precision liquid level detection reference information G [N-1] corresponding to the difference value D [N-1],
(Cβ) When the difference value D [c] does not satisfy the high-precision detection condition, standard accuracy liquid level detection reference information H [c corresponding to the difference value D [c] and the difference value D [c] ] To detect the liquid level based on the liquid level. A magnet that moves up and down according to the liquid level of the liquid stored in the tank;
A plurality of magnetic intensity sensors S [1] to S [N] (N is a natural number of 4 or more), which are sequentially arranged in the vertical direction and spaced from each other and output a value corresponding to the distance from the magnet;
A difference value D [i] is calculated by subtracting the output value of the magnetic intensity sensor S [i + 1] from the output value of the magnetic intensity sensor S [i] (i is a plurality of natural numbers from 1 to N-1). Difference value calculating means;
The difference value D [i] in part or all of the range between the position of the magnet where the difference value D [i] is maximum and the position of the magnet where the difference value D [i] is minimum High-precision liquid level detection reference information G [i] indicating the relationship with the liquid level, the position of the magnet at which the difference value D [i] is maximized, and the difference value D [i] is minimized. Standard accuracy liquid level detection reference information H [i] indicating the relationship between the difference value D [i] and the liquid level in part or all of the range other than the range between the magnet position, and a predetermined value Information storage means in which the high-precision detection conditions are stored;
Liquid level detection means,
The magnetic intensity sensor S [1] is arranged so that the output value becomes maximum when the position of the magnet is one end in the movable range,
The magnetic intensity sensor S [N] is arranged so that the output value becomes maximum when the position of the magnet is the other end in the movable range,
The liquid level detection means
(A) The difference value D [j] (j is a natural number of 1 from 1 to N−2) of the difference values D [i] is negative, and the difference value D [i ], The sign of the difference value D [j + 1] is positive,
(Aα) The difference value D [a] other than the difference value D [j] and the difference value D [j + 1] (a is one or a plurality of natural numbers other than j and j + 1 from 1 to N−1). When the high-precision detection condition is satisfied, the high-precision liquid level detection reference information G [j] corresponding to the difference value D [j] and the difference value D [j], or the difference value D [j + 1] and Detecting the liquid level based on high-precision liquid level detection reference information G [j + 1] corresponding to the difference value D [j + 1],
(Aβ) When the difference value D [a] does not satisfy the high-precision detection condition, standard accuracy liquid level detection reference information H [a corresponding to the difference value D [a] and the difference value D [a] ] To detect the liquid level based on
(B ′) When the sign of the difference value D [1] of the difference values D [i] is positive, the high-accuracy liquid level corresponding to the difference value D [1] and the difference value D [1] Detecting the liquid level based on detection reference information G [1],
(C ′) When the sign of the difference value D [N−1] of the difference values D [i] is negative, it corresponds to the difference value D [N−1] and the difference value D [N−1]. A liquid level detection apparatus configured to detect the liquid level based on high-precision liquid level detection reference information G [N-1]. The liquid level detection means
(A1) Starting the code determination from one difference value D [M] (M is a natural number from 1 to N−1) selected from the difference value D [i],
(A2) When the sign of the difference value D [M] is determined to be positive, the sign determination is sequentially advanced toward the difference value D [1], and the difference value D [j + 1] (j is M− When the sign is finally determined to be positive in 1) and the sign is first determined to be negative in the difference value D [j],
(A2α) When the difference value D [a] satisfies the high-precision detection condition, the difference value D [j] and the high-precision liquid level detection reference information G [j] or the difference value D [j + 1] And the high-precision liquid level detection reference information G [j + 1], the liquid level is detected,
(A2β) When the difference value D [a] does not satisfy the high accuracy detection condition, the liquid level is determined based on the difference value D [a] and the standard accuracy liquid level detection reference information H [a]. Detect
(A3) When the sign of the difference value D [M] is determined to be negative, the sign determination is sequentially advanced toward the difference value D [N−1], and the difference value D [j] (j is When the sign is finally determined to be negative in M to N−2) and the sign is first determined to be positive in the difference value D [j + 1],
(A3α) When the difference value D [a] satisfies the high-precision detection condition, the difference value D [j] and the high-precision liquid level detection reference information G [j] or the difference value D [j + 1] And the high-precision liquid level detection reference information G [j + 1], the liquid level is detected,
(A3β) When the difference value D [a] does not satisfy the high accuracy detection condition, the liquid level is determined based on the difference value D [a] and the standard accuracy liquid level detection reference information H [a]. The liquid level detection device according to claim 1, wherein the liquid level detection device is configured to detect.   When the number N of the magnetic intensity sensors S [1] to S [N] is an even number, the sign determination start number M of the difference value D [M] for starting the sign determination of the difference value D [i] The number N / 2 is selected in advance, or when the number N is an odd number, (N-1) / 2 or (N + 1) / 2 is selected in advance as the code determination start number M. 4. The liquid level detecting device according to 3.   In the next detection from the difference value D [k] (k is a natural number of 1 from 1 to N-1) in which the liquid level detection means determines the sign last among the difference values D [i]. It is configured to select k as the code determination start number M of the difference value D [M] for starting the code determination among the difference values D [i] so as to start the code determination. The liquid level detecting device according to claim 3.   The difference value D [a] is at least one of the difference value D [j-1] and the difference value D [j + 2] of the difference value [i]. The liquid level detection apparatus as described in any one of -5.

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