ITEM QUANTITY RECORDING DEVICE

Abstract

An object quantity detection device comprises a container configured to hold a solidifiable liquid object, an electrode extending vertically in the container and configured to detect a change in capacitance associated with a change in position in the vertical direction of a liquid surface of the object or an external surface of the solidified object, and a determination unit configured to continuously or intermittently detect, based on the electrode's capacitance, a position of the liquid surface or the external surface of the object in the container in order to obtain an object permittivity from the electrode's capacitance and to determine a state of the object based on the obtained permittivity.

Description

TECHNICAL FIELD

[0001] The present disclosures relate to an article quantity detecting device for a solidifiable liquid article, etc. BACKGROUND

[0002] Conventionally, an item quantity detecting device that detects a water quantity, etc., is known, and the item quantity detecting device is provided and used in an ice making device. A conventional ice making device includes an ice tray formed of an insulator, a water supply part for supplying water to the ice tray, an electrostatic capacitance sensor having two or more electrodes attached to the ice tray and each insulated, a water quantity detecting section for detecting a water quantity in the ice tray supplied by the water supply part based on a change in electrostatic capacitance between the electrodes of the electrostatic capacitance sensor, and a driving part for rotating and elastically deforming the ice container into a state where an opening of the ice container is directed downward after detectingthat the water in the ice container is frozen, and wherein the electrodes of the electrostatic capacitance sensor are fixed to an outer surface of the ice container by a displacement absorption member that can be elastically deformed (see, for example, Patent Literature (PTL) 1). CITATION LISTPATENT LITERATURE

[0003] [PTL 1] Japanese Patent Laid-Open Publication No. 2012-207824 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] It should be noted that the article quantity detecting device in question, which is used for an ice making device, detects an amount of water and determines whether the water is frozen, but cannot determine to what extent the water is frozen or how much water is present.

[0005] Therefore, the present embodiment aims to provide an article quantity detecting apparatus capable of determining the quantity and state of a solidifiable liquid article in a container. MEANS TO SOLVE THE PROBLEM

[0006] An object quantity detection device includes a container configured to contain a solidifiable liquid object, an electrode extending in a vertical direction in the container and configured to enable detection of a capacitance change accompanying a position change in the vertical direction of a liquid surface of the object or an outer surface of the object that has solidified, and a determination unit configured to continuously or intermittently detect, based on the capacitance of the electrode, a position of the liquid surface or the outer surface of the object in the container, to obtain a permittivity of the object from the capacitance of the electrode, and to determine a state of the object based on the obtained permittivity. EFFECT OF THE INVENTION

[0007] An object quantity detecting device capable of determining the quantity and state of a solidifiable liquid object in a container may be provided. BRIEF DESCRIPTION OF THE DRAWINGS [ Fig. 1] A drawing illustrating a configuration of an article quantity detecting device 100 of the embodiment. [ Fig. 2] A drawing showing an electrostatic sensor 110. [ Fig. 3] A drawing showing an example of a result of calculating the height of a water surface. [ Fig. 4] A drawing describing a difference in the capacitance of the electrostatic sensor 110 depending on a difference in the height of a surface of a washing liquid 20A. [ Fig. 5A] A drawing showing the electrostatic sensor 110 used for a third correction method. [ Fig. 5B] A drawing of a result of an actual measurement by the third correction method. [ Fig. 6] A drawing illustrating a sixth correction method. [ Fig. 7] A drawing showing a flowchart describing processes for detecting the surface height H and a freezing state of the washing liquid 20A. [ Fig. 8] A drawing describing a method for correcting a change in capacitance associated with a gradient. DESCRIPTION OF THE PREFERRED EMBODIMENT

[0008] An embodiment of the present invention will be described below with reference to the accompanying drawings. <AUSFÜHRUNGSFORM>

[0009] Fig. 1 is a drawing illustrating a configuration of an article quantity detecting device 100 of the embodiment. Fig. 1 shows a vehicle system 10 in addition to the object quantity detection device 100. The vehicle system 10 includes an ECU (Electronic Control Unit) 11 and a power source 12. The vehicle system 10 is, as an example, a system for controlling electronic devices of the vehicle, and any type of electronic device may be applicable. For example, ADAS (Advanced Driver-Assistance Systems) may be used. The ECU 11 controls the vehicle system 10. The power source 12 supplies 12 V DC from an electrical power source, a vehicle battery, and the like.

[0010] The object quantity detection device 100 is a device for detecting the amount of washer fluid 20A stored in a vehicle washer fluid tank 20. When mud, dust, insects, etc., adhere to a camera or optical sensor of a self-driving vehicle or a vehicle with an automatic driving function equipped with a vehicle system 10 such as ADAS, correct images or optical information cannot be obtained; accordingly, systems for cleaning the camera of the optical sensor with washer fluid have been developed.

[0011] The vehicle system 10 detects the amount of washer fluid 20A in the tank 20 to determine whether safe driving is possible. It should be noted that at low outside temperatures, such as in winter, the washer fluid may be frozen. If the washer fluid 20A is frozen, it may not be able to be sprayed as a liquid.

[0012] Therefore, the article quantity detecting device 100 detects a vertical position of a liquid surface of the washing liquid 20A or the surface of the washing liquid 20A in the state of being at least partially frozen, and determines whether the washing liquid 20A is frozen.

[0013] In the present embodiment, a state of the washing liquid 20A refers to whether it is in a non-frozen liquid state or a frozen state. The frozen state may refer to a completely frozen state, but may also refer to a state in which the washing liquid 20A is difficult to spray out of the tank 20. In the present embodiment, the frozen state refers to the state in which the washing liquid 20A is difficult to spray out of the tank 20.

[0014] Furthermore, the washing liquid 20A is an example of a solidifiable (freezable) liquid object. Hereinafter, the washing liquid 20A may refer not only to a liquid state, but also to a solid state or a mixture of a liquid and a solid. Furthermore, a surface height of the washing liquid 20A refers to the vertical position of the liquid surface of the washing liquid 20A in the liquid state or the vertical position of the surface of the washing liquid 20A in the frozen state.

[0015] The object quantity detection device 100 includes a control board 101, an electrostatic sensor 110, an IC (Integrated Circuit) chip 120, and an LDO (Low Dropout) 130. In one example, the electrostatic sensor 110, the IC chip 120, and the LDO 130 are arranged on one control board 101, but they may also be arranged on different control boards, etc. The control board 101 is a conductor substrate. Furthermore, the electrostatic sensor 110 is arranged in addition to Fig. 1 based on Fig. 2 described. Fig. 2 is a drawing showing an electrostatic sensor 110 and illustrating a front view of the electrostatic sensor 110.

[0016] As in Fig. 2, the electrostatic sensor 110 is configured to have electrodes S0, S1, S2, S3, SS1 and SS2 on an insulated substrate (not shown) and attached to an outer surface of the tank 20 by a tape or an adhesive, etc. Fig. Figure 1 is a simplified drawing in which the electrodes SS1 and SS2 are omitted. As in Fig. 1, the electrostatic sensor 110 is provided so as to extend along the vertical direction on a side wall of the tank 20 to enable the detection of the vertically changing liquid surface. Fig. The shapes of the electrodes S0, S1, S2, S3, SS1, and SS2 shown in Figure 2 are the shapes of the surfaces arranged on the side surface of the tank 20. The electrodes S0, S1, S2, S3, SS1, and SS2 are plate-shaped electrodes.

[0017] Electrodes S0, S1, S2, S3, SS1, and SS2 are capacitively coupled to a metallic part (ground part) of a ground potential of a vehicle body and the like, on which vehicle system 10 and object quantity detection device 100 are mounted. Hereinafter, the capacitances of electrodes S0, S1, S2, S3, SS1, and SS2 refer to the values ​​of the electrostatic capacitances between electrodes S0, S1, S2, S3, SS1, and SS2 and the ground part of the vehicle.

[0018] Electrodes S0, S1, S2, S3, SS1, and SS2 are connected to the IC chip 120. Electrodes S0, S1, S2, and S3 are provided to detect a vertical position of the liquid surface of the washing liquid 20A and to detect the state of the washing liquid 20A. Electrodes SS1 and SS2 are used to correct the capacitances of electrodes S0, S1, S2, and S3.

[0019] The electrodes S0, S1, S2, and S3 are arranged in this order from the bottom to the top. The electrodes S0, S1, S2, and S3 are shaped to divide a rectangle, whose surface shape is vertically elongated and which is arranged on the side surface of the tank 20, by three parallel oblique lines. The lowest and uppermost of the three lines each pass through a highest and lowest vertex of the rectangle, and the longitudinal center of the one middle line passes through the center of the rectangle.

[0020] Both electrodes S0 and S3 have triangular surfaces located on the lateral surface of the tank 20, and they correspond in shape. The triangles of electrodes S0 and S3 are the triangles obtained by dividing a quadrilateral by its diagonal.

[0021] The shapes of the electrodes S1 and S2 correspond to the surfaces to be arranged in the side surface of the tank 20, and they are parallelograms resulting from the combination of the shapes of the two electrodes S0 and S3. Thus, the electrodes S1 and S2 consist of two triangles resulting from the division of a quadrilateral by its diagonal.

[0022] The heights of the lower end of electrode S0 and the lower end of electrode S1 are equal, and they are higher than the lower end of the tank 20. The heights of the upper end of electrode S3 and the upper end of electrode S2 are equal, and they are lower than the upper end of the tank 20. The heights of the lower end of electrode S0 and the lower end of electrode S1 are denoted as X0, and the heights of the upper end of electrode S3 and the upper end of electrode S2 are denoted as X3. When the height of the surface of the washing liquid 20A in the tank 20 is between X0 and X3, the surface of the washing liquid 20A always coincides with two of the electrodes S0-S3. Therefore, the electrodes S0 and S1, which are vertically adjacent, are an example of an electrode pair, the electrodes S1 and S2 are an example of an electrode pair, and the electrodes S2 and S3 are an example of an electrode pair.In addition, the details of the heights X0-X3 are described below. Furthermore, the distances between electrodes S0 and S1, between electrodes S1 and S2, and between electrodes S2 and S3 are sufficiently small that they can be neglected during the actual measurement while ensuring insulation.

[0023] The IC chip 120 is a chip element including an AFE (Analog Front End) 120A and an MCU (Microcomputer Unit) 120B. The IC chip 120 is connected to the ECU 11 of the vehicle system 10, for example, via a communication cable 40 for a LIN (Local Interconnect Network).

[0024] The AFE 120A is connected to the electrodes S0, S1, S2, S3, SS1, and SS2 of the electrostatic sensor 110 and digitally converts the capacitances of the electrodes S0, S1, S2, S3, SS1, and SS2 and outputs the capacitances to the MCU 120B. Furthermore, voltage is applied to the electrodes S0, S1, S2, S3, SS1, and SS2 of the electrostatic sensor 110 by applying an AC voltage from a power source (not shown) or a shield electrode (not shown) and capacitively coupling it with the shield electrode.

[0025] The MCU 120B is realized by a computer including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), an input-output interface, an internal bus, and the like.

[0026] The MCU 120B includes a determination unit 121, a detector 122, and a memory 123. The determination unit 121 and the detector 122 represent the functions of the programs that the MCU 120B executes as functional blocks. Furthermore, the memory 123 represents the function of the memory of the MCU 120B. Furthermore, the description of other processing parts of the MCU 120B, except for the determination unit 121 and the detector 122, will be omitted.

[0027] The determination unit 121 determines the height of the liquid surface of the washing liquid 20A, or the surface of the washing liquid 20A in the state in which it is at least partially frozen, as a continuous or intermittent height value. Furthermore, the determination unit 121 determines whether the washing liquid 20A is frozen based on the detected surface height, the relative permittivity in the frozen state of the washing liquid 20A, and the capacitance of the electrostatic sensor 110. To determine whether the washing liquid 20A is frozen, a difference between the relative permittivity (80.4) in the liquid state and the relative permittivity (4.2) in the frozen state of the washing liquid 20A is used.

[0028] When the height of the washing liquid 20A is determined, the determination unit 121 determines the height of the center of gravity of the washing liquid 20A and determines the height of the liquid surface of the washing liquid 20A by doubling the height of the center of gravity. The determination unit 121 determines the Fig. 2 when determining the height of the center of gravity of the washing liquid 20A.

[0029] X0 refers to the height of the lower end of the electrode S0, X1 refers to the height of the vertical center of the electrode S1, X2 refers to the height of the vertical center of the electrode S2, and X3 refers to the height of the upper end of the electrode S3. For example, if the height from the lower end to the upper end of the electrodes S0-S3 is 300 mm, X0 = 0 mm, X1 = 100 mm, X2 = 200 mm, and X3 = 300 mm, and the values ​​of X0-X3 are fixed.

[0030] The determination unit 121 determines the height H of the washing liquid 20A according to the following formula (1). [Formula 1] H=2×∑(Xn×An) / ∑An

[0031] In Formula 1, X refers to n to the values ​​X0-X3. A n refers to the electrostatic capacitances of the electrodes S0, S1, S2 and S3.

[0032] The following describes one meaning of Formula 1. First, the values ​​of the electrostatic capacitance of the respective electrodes are proportional to the vertical areas of the liquids or solids with which the respective electrodes come into contact. Furthermore, the vertical areas are proportional to the masses of the liquids or solids within the vertical range of the respective electrodes. That is, the values ​​of the electrostatic capacitance of the respective electrodes correspond to the masses of the liquids or solids within the range corresponding to the respective electrodes. It should be noted that the position of a center of gravity can generally be determined by a weighted average of the masses and distances of the respective elements. Therefore, the center of gravity of the liquid or solid can be determined by a weighted average of the capacitances (corresponding to the masses) and the distances of the respective electrodes (Σ (X n × An ) / ΣA n ) can be determined. Since the height of the liquid or solid is twice as high as the position of the center of gravity (Σ (X n × A n ) / ΣA n ), the surface height can be calculated using formula 1.

[0033] The following shows an example of a result of actual calculation of the liquid surface height in a case where the washing liquid is liquid using Formula 1, and describes that the liquid surface height can actually be found by Formula 1. Fig. Figure 3 is a drawing showing an example of the result of calculating the liquid surface height. Table 1 is a drawing showing an example of the result of calculating the liquid surface height.

[0034] Example 1 is shown in Table 1, assuming that the liquid surface is at a height of 250 mm, as in Fig. shown. In addition to Example 1, four calculation results are listed in Table 1.

[0035] Since the relative permittivity of the washing liquid is similar to water and sufficiently higher than the permittivity of air, the capacitances measured at the respective electrodes are proportional to the areas of the electrodes immersed in the liquid. Assume that the capacitance is 50 pF when the entire electrode S0 is immersed in the liquid. In Example 1, S0 and S1 are completely immersed in the liquid, and the area of ​​electrode S1 is twice that of electrode S0, therefore, S0 = 50 pF and S1 = 100 pF are measured. For electrode S2, the value corresponding to the range 100-200 mm is 50 pF. and the capacitance corresponding to the range 200-250 mm and the area of ​​the range 200-300 mm is 50 pF × (1 - 1 / 2 × 1 / 2) = 37.5 pF, and the capacitance of electrode S2 is 50 + 37.5 = 87.5 pF. The capacitance of electrode S3, as the area corresponding to the range 200-250 mm, is 50 pF × (1 / 2 × 1 / 2) = 12.5 pF.

[0036] Furthermore, by calculating the height of the liquid surface using Formula 1 according to the measured values ​​of the respective electrodes to be measured, H = 2 × (0×50 + 100×100 + 200×87.5 + 300×12.5) / (50 + 100 + 87.5 + 12.5) = 250 mm, which corresponds to the assumed height of the liquid surface from Example 1. The height of the liquid surface can therefore be determined from the capacitances of the respective electrodes.

[0037] Similarly, the results of determining the capacitances of the respective electrodes that change an assumed liquid surface height and examples of the results of calculating the liquid surface height obtained from the capacitances of these respective electrodes are shown in Table 1. As can be seen from Table 1, the assumed liquid surface height is consistent with the liquid surface height calculated from the capacitances, and it is confirmed that the liquid surface height can be obtained from Formula 1. Since the capacitance is proportional to the permittivity, as can be seen from Formula 1, the calculated value of H does not change even if the permittivity changes. It should be noted that when all the capacitances of the electrodes S1, S2, and S3 are zero, although the denominator of Formula 1 becomes zero, the water level height in this case is zero.

[0038] Furthermore, the determination unit 121 determines whether the washing liquid 20A is frozen or liquid based on the detected surface height, the capacitance of the electrostatic sensor 110, and the relative permittivity of the washing liquid 20A in the frozen state or in the liquid state by the following formula 2. A coefficient C is configured taking into account the relative permittivity of the washing liquid 20A in the liquid state or in the frozen state. The value of the coefficient C can be configured by determining the extent to which the washing liquid 20A is frozen when it becomes difficult to spray, according to a shape or volume of the tank 20.That is, since the capacitance is proportional to the permittivity, there are few capacitances to be measured according to the surface height, and when Formula 2 is applicable, the determination unit 121 determines that the washing liquid 20A is frozen, assuming that the permittivity is low.

[0039] Furthermore, the relative permittivity of water is 80.4 and the relative permittivity of ice is 4.2, and the relative permittivities of the washing liquid 20A in the liquid and frozen states are similar to these values. Since the relative permittivity values ​​vary greatly between the liquid and frozen states, it is easy to determine whether the washing liquid 20A is frozen by correctly configuring the coefficient C. [Formula 2] H×C≧∑A(n)

[0040] Similarly, it can be determined whether a liquid state is present by determining whether the capacitance measured according to the surface height is greater than that in the frozen state. Furthermore, by appropriately determining a threshold value, it is also possible to determine a state that is still in development, e.g., a sorbet-like state during a liquid-to-solid transition.

[0041] The detector 122 reports data regarding the surface height H of the washer fluid 20A determined by the determination unit 121 to the ECU 11 of the vehicle system 10. If the determination unit 121 determines that the washer fluid 20A is frozen, the detector 122 also reports data related to the freezing to the ECU 11 of the vehicle system 10.

[0042] The memory 123 stores the data of the capacitances of the electrodes S0, S1, S2, S3, SS1, and SS2, the heights X0-X3, the surface height H of the washing liquid 20A, and the like. To determine a moving average of the height H or to refer to the results of the determination of the last five seconds, which represent continuous freezing, the memory 123 stores the data of the height H found in the past, the data of the results of the past determination, or the like.

[0043] The LDO 130 is connected to the power source 12 of the vehicle system 10 via a power cable 30. The LDO 130 is a regulator capable of outputting a fixed voltage lower than an input voltage and is a power supply IC. The LDO 130 lowers the voltage of the DC power supplied by the power source 12 of the vehicle system 10 from 12 V to 5 V and supplies the power to the MCU 120B.

[0044] Corrections are described below. Furthermore, corrections are not always necessary. <ERSTES KORREKTURVERFAHREN>

[0045] First, a first correction method will be described. As described above, the water level is basically obtained by Formula 1, but since the denominator of Formula 1 is a sum of the measured values ​​of each electrode, there is a problem that a deviation between the calculated value of the surface height and the actual surface height becomes large, especially in the case where all the measured values ​​are small, that is, in the case where the water level is low, there is a problem that needs to be solved when high-accuracy detection is required. One of the causes is the capacitance C2 caused by water located below the sensing range of the sensor. That is to say, the capacitances of each electrode in an area below the sensing range of the sensor should be zero in the first place, but in fact, the capacitance C2 caused by the water below the sensing range is measured.Therefore, the capacitance used to measure the water level must be a value at which C2 is subtracted from the measured value. Furthermore, a correction of electrode S0, which is performed for correction in the low water level region, is described as mentioned above, and a corresponding correction can be performed in electrode S1. The following is a description based on . Fig. 4.

[0046] Fig. Fig. 4 is a diagram illustrating a difference in the capacitance of the electrostatic sensor 110 depending on a difference in the surface height of the washing liquid 20A. Furthermore, the electrodes S0, S1, S2, S3, SS1, and SS2 are omitted. In a Fig. In the example shown in Figure 4 (A), a vertical distance between a ground part GND and the tank is configured to 20 mm, a vertical distance between a bottom of the tank 20 and the lower end of the electrode S0 is configured to 20 mm, and a vertical distance between the lower end and the upper end of the electrode S0 is configured to 100 mm. This is the same in Fig. 4 (B) and Fig. 4 (C).

[0047] In Fig. 4 (A), the washing liquid 20A is not contained in the tank 20. In this case, the capacitance C1 between the electrode S0 and the ground part GND, neglecting the thickness of the tank 20, can be considered equal to the capacitance Ca0 of the case where air is present between the electrode S0 and the ground part GND, and can be approximated by Ca0 = 1 × ε0 × S / 140. The value of 1 multiplied by ε0 is the relative permittivity of the air. S refers to the surface areas of the electrodes S0-S3 of the electrostatic sensor 110. The reference numeral 140 denotes the distance between GND and the electrode S0.

[0048] In Fig. 4 (B), the surface height of the washing liquid 20A (liquid state) in the tank 20 is as high as the lower end of the electrode S0. In this case, the capacitance C2 between the electrode S0 and the ground part GND is a sum of the capacitance Ca1 of the upper part higher than the washing liquid 20A, the capacitance Cw of the inner part of the washing liquid 20A, and the capacitance Ca2 of a part between the tank 20 and the ground part GND. They can be approximately calculated as follows: Ca1 = 1 × ε0 × S / 100, Cw = 80.4 × ε0 × S / 20, and Ca2 = 1 × ε0 × S / 20. The value 80.4 multiplied by ε0 with respect to Cw is a relative permittivity of the washing liquid 20A in the liquid state.

[0049] In Fig. 4 (C), the surface height of the washing liquid 20A (liquid state) in the tank 20 is equal to the top of the electrode S0. In this case, the capacitance C3 between the electrode S0 and the ground part GND is a sum of the capacitance Cw of the inner part of the washing liquid 20A and the capacitance Ca2 of a part between the tank 20 and the ground part GND. They can be approximated as Cw = 80.4 × ε0 × S / 120 and Ca2 = 1 × ε0 × S / 20.

[0050] Consequently, a ratio of the capacitance C1 between the electrode S0 and the ground part GND in the Fig. 4 (A), the capacitance C2 between the electrode S0 and the ground part GND in the state shown in Fig. 4 (B) and the capacitance C3 between the electrode S0 and the ground part GND in the state shown in Fig. 4 (C) shown condition 100 : 116 : 651.

[0051] When the surface of the washing liquid 20A is higher than the lower end of the electrode S0, it is considered that a change in capacitance corresponding to the water level of the washing liquid 20A is appropriately detected, but when the surface of the washing liquid 20A is lower than the lower end of the electrode S0, because the washing liquid 20A and the electrode S0 do not coincide vertically, it is considered that a value measured at the electrode S0 has a large error, and the water level obtained by Formula 1 also has a large error. Therefore, when the capacitance measured at the electrode S0 is equal to or larger than the capacitance of the state where the tank 20 contains no water, the correction is performed here.

[0052] Specifically, if the capacitance of C1 is denoted as k × 100 (k is a constant) F, C2 is k × 116F, and C3 is k × 651F. Since C3 is the largest capacitance measured by electrode S0 here, it is 500 pF. Therefore, in this example, k = 0.77, C1 = 77 pF, C2 = 89 pF, and C3 = 500 pF. When the capacitance of electrode S0 is between C1 and C2, that is, between the state without washing liquid 20A and the state reaching the bottom of electrode S0, the measured value is reduced and the capacitance of electrode S0 is corrected to zero. In addition, the measured value of the electrode S0 is corrected by subtracting C2 when the value of the electrode S0 is above C2 and equal to C3 or less, that is, when the level of the washing liquid 20A is as high as from the lower end of the electrode S0 to the upper end of the electrode S0 or higher, then the measured value of the electrode S0 is corrected by subtracting C2.

[0053] In addition, if the measured value of electrode S0 is C2 or less, a correction can be made to zero the value, and if it exceeds C2, a correction can be made to subtract C2. A similar correction can also be made to electrode S1. If the value of electrode S0 is above C2 and equal to or less than C3, the maximum capacity would be C3 - C2 if only a simple correction were made by subtracting C2; if the value of electrode S0 exceeds C2, a correction can be made by subtracting C2 and multiplying the resulting value by C3 / (C3 - C2). Furthermore, the water level is determined according to formula 1, and the freezing state of the washing liquid is determined according to formula 2 using the measured values ​​thus corrected. <ZWEITES KORREKTURVERFAHREN>

[0054] A second correction method is described below, which is used for low water levels. In this correction method, an electrode is extended below the water level measuring range. That is, in the Fig. In the examples shown in Figures 4 (A)-(C), the vertical distance between the bottom of the tank 20 and the lower end of the electrode S0 is 20 mm, and there are no electrodes, but the electrode S0 is extended and provided in the area. Thus, the capacity of the electrode S0 can be increased even when the surface of the washing liquid 20A is 20 mm away from the bottom of the tank 20, as shown in Figure 4. Fig. 4 (B). The actual liquid surface height of X0 can then be determined by determining the distance between the bottom of the tank 20 and the surface of the washing liquid and subtracting 20 mm from the determined surface height. In this way, the measurement accuracy within the measurement range can be improved. <DRITTES KORREKTURVERFAHREN>

[0055] A third correction method, which is used in the case of low water levels, is described below. Although the second correction method is a method in which an electrode is actually provided, the third method does not provide an electrode and performs a similar process to the second correction by calculation. Fig. 5A is a drawing showing the electrostatic sensor 110 used for the third correction method.

[0056] In particular, as in Fig. 5A, virtual electrodes S01 and SX having the same shape as the electrodes S1 and S0 within the height X0-X1 are provided. The value of the capacitance of the electrode S01 found by the calculation corresponding to the washing liquid between the height XA and the height X0 is added to the actually measured value of the electrode S0, and the capacitance of the electrode SX corresponding to the washing liquid between the height XA and the height X0 is found. In addition, the surface height of XA is obtained by Formula 1. In addition, the actual surface height of X0 is obtained by subtracting the height between the height XA and the height X0 from the obtained surface height. This can increase the measurement accuracy because the denominator of Formula 1 can be increased in the measurement range of the water level.

[0057] Fig. Figure 5B is a drawing of the actual measurement result by the third correction method. In Fig. In Figure 5B, the horizontal axis represents the actual water level, and the vertical axis represents the calculated water level obtained by calculation from the actual measured data of each electrode. The thin solid line represents the ideal values ​​where the calculated values ​​are consistent with the actual water level, the dashed line represents the calculated water level values ​​without correction, and the thick solid line represents the water level calculation results by the third correction method. In the low water level range, the actual water level values ​​and the calculated values ​​are almost consistent. <VIERTES KORREKTURVERFAHREN>

[0058] As a fourth correction method, the water level can be detected by applying a γ-correction with an exponent greater than one, e.g., two, to perform a correction in which a smaller capacitance is reduced by a greater amount compared to a larger capacitance. This increases the effectiveness of the electrode in the area where the washing liquid is present. Furthermore, in such cases, the γ-correction can be applied only to the low water level area, rather than applying it to the surface height measurement across the entire measurement area. <FÜNFTES KORREKTURVERFAHREN>

[0059] Since the respective electrodes represent a predetermined value due to the effects of stray capacitance even when the washing liquid is not included, errors occur in the calculations, and a fifth correction method is described as a correction method for the errors.

[0060] The fifth correction method is a method for correcting all values ​​of the electrodes S(n+1), S(n+2), and S(n+3) to zero when the value of an electrode Sn is a predetermined value or less. That is, when the value of the electrode Sn is a predetermined value or less, the surface is positioned near the lower end of the electrode Sn; therefore, the electrodes S(n+1), S(n+2), and S(n+3) positioned higher than the electrode Sn are determined not to be immersed in the washing liquid; accordingly, an effect of capacitances measured in the state where the washing liquid is not contained can be reduced by correcting the capacitances to zero. <SECHSTES KORREKTURVERFAHREN>

[0061] A sixth correction method is shown below, which has the same purpose as the fifth correction method. In the sixth correction method, the Fig. 6 is used. Fig. 6 is a drawing showing the sixth correction method and a cross section of the electrostatic sensor 210.

[0062] In addition, elements corresponding to those of the electrostatic sensor 110 are designated and described with the same reference numerals. Although the electrodes designated S0-S3, SS1, and SS2 actually consist of separate parts, and a reference electrode SR also consists of a plurality of separate parts, these electrodes are Fig. 6, each shown as a single part. The reference electrode SR is an example of reference electrodes. The electrostatic sensor 210 differs from the electrostatic sensor 110 in that the reference electrode SR and the shield electrode SS are provided, and this aspect is included in the following description.

[0063] Like the electrostatic sensor 110, the electrodes S0-S3, SS1, and SS2 are formed on the same surface of the substrate B and arranged opposite the tank 20. The reference electrode SR has the same shape as the electrodes S0-S3, SS1, and SS2 and is provided on a surface opposite the surface on which the electrodes S0-S3, SS1, and SS2 are provided. The shield electrode SS is arranged between the electrodes S0-S3, SS1, and SS2 and the reference electrode SR in the thickness direction of the substrate B. The shield electrode SS is capacitively coupled to the electrodes S0-S3, SS1, SS2, and the reference electrode SR by being connected to ground or driven by alternating current. Therefore, although the capacitances of the electrodes S0-S3, SS1, and SS2 are affected by the washing liquid 20A in the tank 20, the electrode SR is not affected by the washing liquid 20A.

[0064] Subsequently, a correction is performed by subtracting the capacitances of the parts of the reference electrode that have the same shape as the corresponding electrodes S0-S3, SS1, and SS2 from the capacitances of these electrodes. In this way, the capacitance caused by the presence of the washing liquid 20A can be determined. That is, although a predetermined capacitance is measured and this varies according to a temperature change without the washing liquid, the effect can be reduced. In addition, the water level is determined by applying the corrected value to Formula 1, and whether it is frozen is determined by Formula 2.

[0065] Note that in this example, the reference electrode has the same shape as electrodes S0-S3, SS1, and SS2. However, this is not limited; it can, for example, be an electrode with a different area. In this case, the value to be subtracted from the measured value is determined by converting it to the areas of electrodes S0-S3.

[0066] Furthermore, in the present example, the shield electrode SS is arranged between the reference electrode SR and the electrodes S0-S3, SS1 and SS2 along an insulated layer of the substrate B, and furthermore, another shield electrode may be arranged on the surface opposite the electrodes S0-S3, SS1 and SS2 of the reference electrode SR along an insulated layer of the substrate B, ie the reference electrode SR may be arranged between the two shield electrodes along the insulated layers of the substrate.

[0067] In addition, the correction of the washer fluid 20A at the lower end of the Fig. 4 and below after the correction has been performed with the electrostatic sensor 210.

[0068] It should be noted that a combination of any of the first to fourth corrections and any of the fifth and sixth corrections may be performed. In this case, any of the first to fourth corrections shall be performed after any of the fifth and sixth corrections. Furthermore, a combination of corrections may be applied, if possible.

[0069] Fig. 7 is a drawing illustrating a flowchart describing processes for detecting the surface height H and the freezing state of the washer liquid 20A in the electrostatic sensor 110 or the electrostatic sensor 210. These operations are performed by the determination unit 121. Note that, although the operations of the determination unit 121 are different in the electrostatic sensor 110 and the electrostatic sensor 210, corresponding operations are denoted by the same reference numerals.

[0070] When the determination unit 121 starts the processes, a power-on reset process is performed (a step S1). Specifically, a process for resetting values ​​of the ROM or RAM or the like is executed.

[0071] The determination unit 121 configures a count value i relating to a number of detections of the heights H to zero (i = 0) (a step S2).

[0072] The determination unit 121 determines the capacitances of the electrode S0-S3 (a step S3).

[0073] With respect to the electrostatic sensor 110, the determination unit 121 performs the aforementioned fifth correction and then the aforementioned first correction. That is, if the capacitance of the electrode S0 is 77-89 pF, the value is corrected to zero. If the value is higher, a correction is performed to subtract 89 pF (step S4). In this case, as mentioned above, a corresponding correction may be made to the electrode S1 during the first correction.

[0074] In addition, with respect to the electrostatic sensor 210, the above-mentioned sixth correction and the above-mentioned first correction are performed (a step S4).

[0075] It should be noted that, as mentioned above, correction itself is not always necessary, depending on the required accuracy, and correction can be either one of the above-mentioned correction methods or a combination of them.

[0076] The determination unit 121 determines the height H according to Formula 1 (step S5). Calculating the height H according to Formula 1 is equivalent to determining the height H.

[0077] The determination unit 121 calculates a moving average of the height H calculated in step S5 and the height H calculated in the last 19 times (a step S6). The moving average can be determined by Formula 3 below. However, j is an integer from 1 to 20, which refers to the twenty heights H between the current step S5 and the step S5 of the last 19 times. Furthermore, N refers to the number of values ​​of the heights H, and N = 20. [Formula 3] H=1 / N×∑j=120Hj

[0078] In step S6, the determination unit 121 detects the height H of the surface of the washing liquid 20A a plurality of times as time passes, and determines the average of the heights H detected a plurality of times as the height H of the surface of the washing liquid 20A.

[0079] The determination unit 121 increments a count value i (i = i + 1) (a step S7).

[0080] The determination unit 121 waits for 250 ms (a step S8).

[0081] The determination unit 121 determines whether i ≥ 20 (a step S9). That is, it determines whether the heights H have been detected 20 or more times.

[0082] If the determination unit 121 determines that i ≥ 20 (S9: NO), the flow returns to step S3. This is because repeated detection of the altitude H is required. If i is less than 20, the determination unit 121 also skips the process of step S6. This is because the necessary altitude data H for finding a moving average is not obtained.

[0083] When the determination unit 121 determines in step S9 that i ≥ 20 (S9: YES), it is determined according to Formula 2 whether a frozen state exists (a step S10).

[0084] If the determination unit 121 determines that there is no freezing condition (S10: NO), a counter value f for determining freezing is set to zero (step S11). That is, f = 0.

[0085] The determination unit 121 causes the notifier 122 to report the moving average of the altitude H determined in S6 to the ECU 11 of the vehicle system 10 (a step S12). Reporting only the altitude H means that no freezing occurs, but data representing that no freezing occurs (non-freezing information) may be reported with the altitude H. When the process of step S12 is completed, the determination unit 121 returns the flow to step S3.

[0086] If the determination unit 121 determines in step S10 that a frozen state exists (S10: YES), it increments a counter value f (step S13). That is, f = f + 1.

[0087] The determination unit 121 determines whether a frozen state has been detected for 20 consecutive times since step S10 out of 19 times after the current step S10 (S10: YES) (a step S14). Since the determinations are performed every 250 ms, the process of step S14 is a process for determining whether a frozen state has been detected for the past five seconds (S10: YES).

[0088] When the determination unit 121 determines that a frozen state has not been present 20 times in a row (S14: NO) (S10: YES), the flow proceeds to step S12.

[0089] If the determination unit 121 determines that a frozen state exists 20 times consecutively (S10: YES) in step S14, it determines that the washer fluid 20A in the tank 20 is frozen, and causes the detector 122 to inform the ECU 11 of the vehicle system 10 of the moving average of the heights H found in step S6 and the data representing the occurrence of freezing (freezing information) (step S15). This completes a series of processes.

[0090] Thus, the determination unit 121 finds the height H of the surface of the washing liquid 20A according to the height of the center of gravity of the washing liquid 20A by Formula 1. In addition, the determination unit 121 determines whether the washing liquid 20A is frozen based on the detected surface height, the relative permittivity in the frozen state of the washing liquid 20A, and the capacitance of the electrostatic sensor 110 according to Formula 2.

[0091] Consequently, the article amount detecting device 100 that can determine the amount and state of the solidifiable liquid article (the washing liquid 20A) in the container (the tank 20) ​​can be provided.

[0092] Since the electrodes S0-S3 are plate-shaped electrodes with electrode pairs having triangular sections obtained by dividing rectangles by their diagonals, and are arranged on the lateral surface of the tank 20, no matter how high the surface of the washing liquid 20A is, two vertically adjacent electrodes (electrode pair) of the electrodes S0-S3 always coincide with the surface. Therefore, if there were an area that did not coincide with the surface, a section would occur where the detected value did not change noticeably. However, since the surface always coincides with the electrodes, non-changing sections in the detected values ​​of the water level do not occur, and it is possible to reduce a detected value of the water level according to the lowering of the water level, and the water level can be measured accurately.

[0093] Furthermore, the determination unit 121 detects the surface of the washing liquid 20A according to the weighted average of a plurality of electrodes S0-S3, and determines the state of the surface position of the washing liquid 20A according to the detected surface height H of the washing liquid 20A, the capacitance of the electrostatic sensor 110, and the coefficient C according to the relative permittivity of the washing liquid 20A in a liquid state or in a solid state. Since the surface position is determined by the weighted average of the heights and capacitances of a plurality of electrodes, the surface height can be measured even when the permittivity of the solid and the liquid are different.Since the permittivities can be determined by the detected height and the value of the electrostatic capacity, and a relative permittivity of water (80.4) and a relative permittivity of ice (4.2) are largely different, the state of the washing liquid 20A can be accurately detected using the difference in the relative permittivities.

[0094] In addition, since the electrodes S0-S3 comprise a plurality of electrode pairs and a plurality of electrode pairs are arranged vertically, the height H and the state of the washing liquid 20A can be detected even if the surface height of the washing liquid 20A varies continuously along a relatively wide vertical range.

[0095] In addition, the surface height was calculated by reducing the capacitance of the washing liquid corresponding to the lower end of the electrostatic sensor. Therefore, the surface height H of the washing liquid 20A can be accurately detected even when the amount of the washing liquid 20A is small.

[0096] Furthermore, the surface height was calculated by arranging the electrodes S0-S3 toward the tank 20, placing the reference electrode SR on the opposite surface along the shield electrode, and subtracting the capacitance of the reference electrode SR from the capacitances of the electrodes S0-S3 to correct to zero. Therefore, the surface height H of the washing liquid 20A can be accurately detected.

[0097] In addition, since the determination unit 121 detects the surface height H of the washing liquid 20A a plurality of times over time and determines the average of the multiple detected heights H as the height H of the surface of the washing liquid 20A, the height H can be accurately detected.

[0098] Furthermore, the detector 122 is included, which informs the ECU 11 of the vehicle system 10 of the freezing information when the determination unit 121 determines the state of the washer fluid 20A as a frozen state, so that the ECU 11 of the vehicle system 10 can be informed of the availability of the washer fluid 20A. When the washer fluid 20A, which is used to clean, in particular, mud, dust, insects, etc., adhering to a camera or optical sensor mounted on a self-driving vehicle or a vehicle with an automatic driving function on which a vehicle system 10 such as ADAS is mounted, is frozen, cleaning cannot be performed, so that the provided object quantity detection device 100 can contribute to safe travel of vehicles.

[0099] Furthermore, in this example, the surface position measurement begins at every predetermined time period; however, it can begin shortly after the pump for spraying the washing liquid has been operated. Otherwise, measurements can be taken at short intervals after the pump for spraying the washing liquid has been operated, whereas conventional measurements are taken at long intervals. Since in this case, the measurements are taken at a time when the surface is changing, the measurements can be accurate and power consumption can be reduced.

[0100] In addition, water level measurement can be reduced or stopped when the vehicle is temporarily stopped and idling is interrupted. In this case, power consumption can be reduced when the current output is low.

[0101] In addition, the water level measurement can be reduced or stopped when a noise level measured by the sensor is small to detect that the vehicle is stopped.

[0102] Furthermore, when the vehicle is driven, the vehicle may be tilted relative to the horizontal surface, and in this case, the tank 20 may also be tilted, and the surface of the washer fluid 20A may be tilted relative to the electrostatic sensor 110. The capacitance fluctuations caused by such tilting can be corrected using the electrodes SS1, SS2.

[0103] Fig. Figure 8 is a drawing describing a method for correcting a capacity fluctuation caused by a tilt. Fig.8 shows the states when the tank 20 is tilted and the positions of the parts of the electrodes SS1 and SS2 immersed in the washing liquid 20A. The electrodes SS1 and SS2 are examples of tilt detection electrodes.

[0104] In this case, a gradient D (%) with respect to the inclination of the tank 20 can be determined by the following formula 4. [Formula 4] D(%)=(1−SS1 / SS2)×100

[0105] The capacitances of the electrodes S0-S3 can be corrected using the gradient D, and the surface height H of the washing liquid 20A can be determined from the corrected capacitances. Furthermore, the state of the washing liquid 20A can be determined using the surface height H of the washing liquid 20A according to the corrected capacitances.

[0106] Specifically, the gradient D can be determined according to Formula 4, wherein the surface area of ​​the washing liquid 20A within the electrodes S0-S3 between the electrodes SS1 and SS2 can be corrected according to the gradient D, and the surface height H of the washing liquid 20A can be determined according to the corrected capacitances. Subsequently, the state of the washing liquid 20A can be determined using the surface height H of the washing liquid 20A according to the corrected capacitances.

[0107] It should be noted that in the previous description, a plurality of electrodes were arranged vertically, and the surface height of the washing liquid 20A was continuously detected along a relatively wide vertical range; however, detection electrodes may be provided, for example, every 10 mm, and heights of 10 mm each, that is, intermittent heights, may be detected.

[0108] Furthermore, the present invention is not limited to these embodiments, but various variations and modifications may be made without departing from the scope of the present invention.

[0109] This application is based on and claims priority from Japanese Patent Application No. 2022-028511 filed with the Japan Patent Office on February 25, 2022, the entire contents of which are hereby incorporated by reference. LIST OF REFERENCE SYMBOLS 10 Vehicle system 20 tanks 20A Washer fluid 100 Item Quantity Detection Device 110 electrostatic sensor S0, S1, S2, S3, SS1, SS2 electrodes 120 IC chips 120B MCU 121 Determination unit 122 detectors QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2022-028511

[0109]

Claims

[1] An object quantity detection device comprising: a container configured to contain a solidifiable liquid article; an electrode extending vertically in the container and configured to enable detection of a change in capacitance associated with a change in position in the vertical direction of a liquid surface of the object or an outer surface of the object that has solidified; and a determination unit configured to continuously or intermittently detect, based on the capacitance of the electrode, a position of the liquid surface or the outer surface of the object in the container, to obtain a permittivity of the object from the capacitance of the electrode, and to determine a state of the object based on the obtained permittivity. [2] The article quantity detecting device according to claim 1, wherein the electrode is a plate-shaped electrode having a plurality of pairs of electrodes having triangular sections obtained by dividing rectangles by their diagonals and is arranged on a side surface of the container. [3] The object quantity detecting device according to claim 2, wherein the determining unit is configured to detect the liquid surface or the outer surface of the object based on a weighted average of capacitances and positions of the plurality of electrode pairs, and to determine the state of the object based on the detected position of the liquid surface or the outer surface of the object and a relative permittivity of the object in a liquid state or in a solid state. [4] The object quantity detecting device according to claim 2 or 3, wherein the plurality of electrode pairs are arranged along a vertical direction. [5] The article quantity detecting device according to any one of claims 2 to 4, further comprising a reference electrode arranged on a side opposite to the electrode and the container along a shield electrode; wherein the determination unit is configured to correct the capacitances of the electrode pairs based on the capacitance of the reference electrode. [6] The object quantity detecting device according to any one of claims 2 to 4, wherein the determining unit is configured to set the capacitance of one or more electrodes to zero when one of a plurality of electrode pairs has a capacitance exceeding a predetermined value, the one or more electrodes being arranged higher than the one of the plurality of electrode pairs. [7] The object quantity detecting device according to any one of claims 2 to 4, wherein the determining unit is configured to correct the capacitance of the electrode pairs when the position of the liquid surface or the outer surface of the object is lower than or equal to a predetermined height. [8] The article quantity detecting device according to any one of claims 2 to 4, wherein the determining unit is configured to calculate a liquid level height by incorporating a capacitance of a virtual electrode pair provided below the plurality of electrode pairs into the calculation. [9] The article quantity detecting device according to any one of claims 1 to 8, wherein the determining unit is configured to detect the position of the liquid surface or the outer surface of the article a plurality of times as time passes, and to obtain an average of the positions of the liquid surface or the outer surface of the article detected a plurality of times as the position of the liquid surface or the outer surface of the article. [10] The article quantity detecting device according to any one of claims 1 to 4, further comprising a notifier configured to notify an external device of the information that the article is in a frozen state when the determining unit determines that the state of the article is the frozen state. [11] An article quantity detecting device according to any one of claims 1 to 10, wherein the article is a washing liquid for a vehicle.

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