JP6680001B2 - Liquid detector - Google Patents

Description

  The present invention relates to a liquid detection device.

  BACKGROUND ART Conventionally, there is known a device that detects the amount of water adhering to an exhaust sensor mounted on an exhaust pipe of an internal combustion engine (for example, see Patent Document 1). In this device, the amount of water adhering to the exhaust sensor is detected based on the change in the resistance value of the heating resistor embedded in the insulating substrate.

JP, 2014-062889, A

  However, with the above device, it is difficult to identify the position where the liquid such as a water drop is attached. This is because when the liquid adheres to the end of the insulating substrate, the adhering liquid is not sufficiently absorbed by the insulating substrate, which lowers the detection accuracy, and it takes a long time for the adhered liquid to reach the heating resistor. This is because it takes time and the responsiveness deteriorates.

  Further, when a droplet such as a water droplet collides with the end portion of the element, the element does not absorb the entire amount of the droplet and a part of the droplet scatters, so that there is a problem that the quantitative accuracy of the droplet decreases.

  Therefore, in view of the above problem, it is an object of the present invention to provide a liquid detection device capable of specifying the liquid adhesion position with high accuracy and quantifying the liquid adhesion amount with high accuracy.

In order to achieve the above object, a liquid detection device according to one aspect of the present invention,
A liquid detection device for detecting a liquid adhesion position and an adhesion amount,
An insulating substrate,
A first detection unit provided on the surface of the insulating substrate, the first detection unit including a plurality of resistors each having a resistance value that changes according to a temperature change;
A second detection unit provided on a side surface of the insulating substrate, the second detection unit including a plurality of resistors each having a resistance value that changes according to a temperature change;
A droplet holding layer formed so as to cover the first detection unit and the second detection unit;
The liquid adhesion position is calculated based on the variation amount of the resistance value of the first detection unit and the variation amount of the resistance value of the second detection unit when the liquid is attached, and the liquid adhesion position is calculated according to the attachment position. And a control unit that corrects the adhered amount.

  According to the disclosed liquid detection device, the liquid attachment position is calculated based on the change amount of the resistance value of the first detection unit and the change amount of the resistance value of the second detection unit when the liquid is attached, Since the liquid adhesion amount is corrected according to the adhered position, it is possible to specify the liquid adhesion position with high accuracy and quantify the liquid adhesion amount with high accuracy.

Schematic of the liquid detection device of the present embodiment Schematic perspective view of the liquid detection element of the present embodiment (1) Schematic perspective view of the liquid detection element of the present embodiment (2) Exploded perspective view of the liquid detection element of the present embodiment (1) Exploded perspective view of the liquid detection element of the present embodiment (2) Schematic cross-sectional view of the liquid detection element of the present embodiment Diagram illustrating the liquid adhesion position Graph showing the waveform of sensor output when liquid adheres to the liquid detection element Flowchart (1) explaining the liquid detection processing of the present embodiment Flowchart (2) explaining the liquid detection processing of the present embodiment Flowchart (3) explaining the liquid detection processing of the present embodiment Flow chart (4) explaining the liquid detection processing of the present embodiment Graph showing the relationship between the liquid adhesion position and the sensor output change amount ratio Graph showing the relationship between the liquid adhesion position and the output correction amount of the first detection unit Graph showing the relationship between the liquid adhesion position and the output change amount of the first detection unit Graph showing the relationship between the liquid adhesion position and the output change amount of the first detection unit before and after correction

  Hereinafter, embodiments for carrying out the invention will be described with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, and duplicate description will be omitted.

  The liquid detection device of the present embodiment is, for example, a device used to detect the adhesion position and the adhesion amount of the liquid that adheres to the exhaust sensor mounted on the exhaust pipe of the internal combustion engine. The liquid detection device according to the present embodiment is not limited to the exhaust pipe of the internal combustion engine, may be mounted on the intake pipe, may be mounted on the duct of the building, and further, like the air conditioner. It may be installed in the duct of various home appliances.

(Liquid detection device)
The liquid detection device of this embodiment will be described based on FIGS. 1 to 6. FIG. 1 is a schematic view of the liquid detection device of this embodiment.

  As shown in FIG. 1, the liquid detection device includes a liquid detection element 10 and a control unit 20. The control unit 20 includes, for example, an arithmetic unit 21, a data collector 22, and a circuit 23.

  2 and 3 are schematic perspective views of the liquid detection element of the present embodiment, and FIG. 3 shows a state in which the liquid droplet holding layer in the liquid detection element of FIG. 2 is omitted. 4 and 5 are exploded perspective views of the liquid detection element of the present embodiment, and show states when the liquid detection element is viewed from the directions of the viewpoint 3A and the viewpoint 3B in FIG. 3, respectively. FIG. 6 is a schematic cross-sectional view of the liquid detection element of the present embodiment, showing a cross section taken along one-dot chain line 2A-2B in FIG.

  The liquid detection element 10 includes an insulating substrate 11, first detection units 12a and 12b, second detection units 13a and 13b, a heater 14, a droplet holding layer 15, leads 16a, 16b, 16c and 16d, 16e and terminals 17a and 17b are included.

The insulating substrate 11 is a long flat plate-shaped member made of an insulating material, and is made of, for example, aluminum oxide (Al ₂ O ₃ ).

  The first detectors 12 a and 12 b are provided in a meandering shape on the surface of the insulating substrate 11. The first detectors 12a and 12b are formed of a resistor whose resistance value changes according to temperature changes, and are formed of, for example, a metal thin film of platinum (Pt) or the like. As a result, when liquid adheres to the first detectors 12a and 12b, the latent heat of vaporization of the liquid lowers the temperature of the first detectors 12a and 12b, and this temperature decrease reduces the resistance value of the resistor. Both ends of the first detectors 12a and 12b are electrically connected to the terminals 17a and 17b through the leads 16a and 16b and the through holes 18a and 18b.

  In the present embodiment, as shown in FIG. 6, the first detection unit 12 a is formed on the upper surface of the insulating substrate 11, and the first detection unit 12 b is formed on the lower surface of the insulating substrate 11. This makes it possible to detect the liquid attached to the surface (upper surface and lower surface) of the insulating substrate 11. The first detectors 12 a and 12 b are each formed by three detectors along the longitudinal direction of the insulating substrate 11. This makes it possible to easily detect the liquid adhesion position in the longitudinal direction of the surface (upper surface and lower surface) of the insulating substrate 11.

  The second detectors 13 a and 13 b are provided on the side surface of the insulating substrate 11. The second detectors 13a and 13b are formed of a resistor whose resistance value changes with temperature changes, and are formed of, for example, a metal thin film such as Pt. As a result, when liquid adheres to the second detectors 13a and 13b, the temperature of the second detectors 13a and 13b decreases due to the latent heat of vaporization of the liquid, and the resistance value of the resistor decreases due to this temperature decrease. Both ends of the second detectors 13a and 13b are electrically connected to the terminals 17a and 17b through the leads 16c and 16d and the through holes 18c and 18d.

  In the present embodiment, as shown in FIG. 6, the second detection units 13a and 13b are formed inside the insulating substrate 11, and a part of the second detecting units 13a and 13b is formed to be exposed at the side surface of the insulating substrate 11. Is provided on the side surface of the insulating substrate 11. More specifically, the second detectors 13a and 13b are formed on the outer peripheral portion of the insulating substrate 11 as shown in FIGS. It is formed so as to be exposed from the insulating substrate 11 on both sides in the longitudinal direction of the flexible substrate 11. Thereby, the liquid adhering to the side surfaces (one side surface in the lateral direction and both side surfaces in the longitudinal direction) of the insulating substrate 11 can be detected.

  The heater 14 is formed inside the insulating substrate 11 between the second detection unit 13a and the second detection unit 13b. The heater 14 is formed in a meandering shape with a heating resistor, and is formed of, for example, a metal thin film of Pt or the like. Both ends of the heater 14 are electrically connected to the terminals 17a via the leads 16e and the through holes 18e. As a result, the heater 14 generates heat by being supplied with current from the power supply device (not shown) through the terminal 17a, the through hole 18e, and the lead 16e.

The droplet holding layer 15 is formed of a porous material so as to cover (cover) the first detection portions 12a and 12b, and is formed of, for example, a porous body of Al ₂ O ₃ . As a result, even if the liquid splashes on the portion of the surface of the insulating substrate 11 where the first detection portions 12a and 12b are formed, the splashed liquid is captured (held) by the droplet retaining layer 15. . Therefore, the flying liquid is prevented from being repelled and immediately separated from the liquid detection element 10, and most of the flying liquid diffuses in the droplet holding layer 15 and reaches the first detection portions 12a and 12b. . As a result, it is possible to change the temperatures of the first detection units 12a and 12b according to the amount of the attached liquid.

  Further, the droplet holding layer 15 may be formed so as to cover the portions of the second detection portions 13a and 13b exposed from the side surface of the insulating substrate 11. As a result, even if the liquid splashes on the exposed side surfaces of the insulating substrate 11 where the second detection units 13a and 13b are exposed, the splashed liquid is retained by the droplet retaining layer 15. Therefore, the flying liquid is prevented from being repelled and immediately separated from the liquid detection element 10, and most of the flying liquid diffuses in the droplet holding layer 15 and reaches the second detection portions 13a and 13b. . As a result, the temperatures of the second detectors 13a and 13b can be changed according to the amount of the attached liquid.

  The leads 16 a, 16 b, 16 c, 16 d, 16 e are formed inside the insulating substrate 11. The leads 16a, 16b, 16c, 16d, 16e are made of a conductive material, for example, a metal thin film of Pt or the like. The lead 16a electrically connects the first detection unit 12a and the terminal 17a. The lead 16b electrically connects the first detection unit 12b and the terminal 17b. The lead 16c electrically connects the second detection unit 13a and the terminal 17a. The lead 16d electrically connects the second detector 13b and the terminal 17b. The lead 16e electrically connects the heater 14 and the terminal 17a.

  The terminals 17a and 17b are formed on the surface of the insulating substrate 11. The terminals 17a and 17b are made of a conductive material, for example, a metal thin film of Pt or the like. In the present embodiment, the terminals 17a are formed on the upper surface of the insulating substrate 11, and the terminals 17b are formed on the lower surface of the insulating substrate 11. The terminals 17a and 17b are electrically connected to the circuit 23 of the control unit 20.

  The control unit 20 detects the liquid amount based on the change amount of the resistance value of the first detection units 12a and 12b and the change amount of the resistance value of the second detection units 13a and 13b when the liquid adheres to the liquid detection element 10. The adhesion position is calculated, and a process of correcting the adhesion amount of the liquid according to the calculated adhesion position is executed. The control unit 20 uses, for example, a calculator 21 that performs calculations, a data collector 22 that stores programs, data, maps (or calculation formulas, tables, etc.), and resistance values output from the liquid detection element 10 as voltage values. A circuit 23 for converting and outputting is included. The map is created in advance by a preliminary experiment or the like and stored in the data collector 22.

  In the present embodiment, the change amount of the resistance value of the first detection unit 12a, 12b and the second detection unit 13a, 13b is converted into the change amount of the voltage value, and the change amount of the converted voltage value (hereinafter referred to as "output change amount"). Of the liquid), the liquid adhesion position is calculated, and the liquid adhesion amount is corrected according to the calculated adhesion position. However, the present invention is not limited to this form, and the liquid resistance of the liquid can be determined based on the change amount of the resistance value without converting the resistance values of the first detection units 12a and 12b and the second detection units 13a and 13b into voltage values. The adhesion position may be calculated and the calculated liquid adhesion amount may be corrected.

(Operation of liquid detection device)
Next, the operation of the liquid detection device will be described based on FIGS. 7 and 8. FIG. 7 is a diagram for explaining the liquid adhering position, and shows a cross section taken along one-dot chain line 6A-6B in FIG. FIG. 8 is a graph showing the waveform of the sensor output when liquid adheres to the liquid detection element, and shows changes in the sensor output (outputs of the first detection unit and the second detection unit) with respect to time. In FIG. 8, a curve S shows the output waveform of the first detector, and a curve I shows the output waveform of the second detector.

  An example of the operation of the liquid detection device will be described when the liquid adheres to the vicinity of the center of the upper surface of the liquid detection element 10 (area Xa in FIG. 7).

  When the liquid adheres to the vicinity of the center of the upper surface of the liquid detection element 10, the adhered liquid diffuses in the droplet holding layer 15 formed so as to cover the first detection unit 12a and reaches the first detection unit 12a. To do. At this time, a part of the liquid that has diffused in the droplet holding layer 15 reaches the second detection unit 13a, though a little. As a result, as shown in FIG. 8, the output of the first detector 12a and the output of the second detector 13a decrease. This is because when the liquid adheres to the first detection unit 12a and the second detection unit 13a, the temperatures of the first detection unit 12a and the second detection unit 13a locally decrease due to the latent heat of vaporization of the liquid. The time t1 in FIG. 8 is the time when the liquid is attached to the liquid detection element 10.

  When a time elapses after the liquid is attached to the upper surface of the liquid detection element 10, the output of the first detection unit 12a and the output of the second detection unit 13a turn from decrease to increase and gradually increase. This is because the temperature of the first detection unit 12a gradually returns to the temperature before the liquid adheres due to the heating by the heater 14 formed inside the liquid detection element 10.

At this time, as shown in FIG. 8, the output change amount of the first detection unit 12a becomes larger than the output change amount of the second detection unit 13a. This is because the amount of the liquid reaching the first detection unit 12a is larger than the amount of the liquid reaching the second detection unit 13a among the liquids attached to the upper surface of the liquid detection element 10. The output change amount of the first detection unit 12a is the output when the first detection unit 12a does not detect the liquid adhesion and the change in the output after the first detection unit 12a detects the liquid adhesion. It is the absolute value of the difference from the output when the amount becomes zero (indicated by " _VA " in FIG. 8). Further, the output change amount of the second detection unit 13a means the output when the liquid detection is not detected by the second detection unit 13a and the change in the output after the liquid detection is detected by the second detection unit 13a. It is the absolute value of the difference from the output when the amount becomes zero (indicated by “V _B ” in FIG. 8).

(Liquid detection processing)
Next, the liquid detection process executed by the control unit 20 will be described based on FIGS. 9 to 16. In the following description, the first detectors 12a and 12b are also referred to as the first detector 12, and the second detectors 13a and 13b are also referred to as the second detector 13.

  The liquid adhesion determination process in the first detection unit 12 will be described based on FIG. FIG. 9 is a flowchart for explaining the liquid detection process of this embodiment, and shows the flow of the liquid adhesion determination process in the first detection unit 12.

First, the control unit 20 acquires the output S _s and the time T _s of the first detection unit 12 (step S11).

Subsequently, the control unit 20 calculates the amount of change in the output _{S s} of the first detection unit 12 for a time _{T s} (slope _{A s)} (step S12). The calculation method of the slope A _s may be, for example, the differential value of the output S _s of the first detection unit 12 or the change amount of the output S _s of the first detection unit 12 at two different times. .

Subsequently, the control unit 20 determines whether or not the absolute value | A _s | of the inclination A _s is equal to or larger than the first predetermined value α (step S13). The first predetermined value α is the change in the output S _s of the first detection unit 12 when the liquid does not adhere to the first detection unit 12 changes to the state where the liquid adheres to the first detection unit 12. It can be the absolute value of the quantity. The first predetermined value α is predetermined, for example, according to the material used for the first detection unit 12, the shape of the first detection unit 12, and the like.

When it is determined in step S13 that the absolute value | A _s | of the slope A _s is equal to or larger than the first predetermined value α, the control unit 20 controls the output S _s1 of the first detection unit 12 and the time T at this time. _s1 is written in the data collector 22 and stored (step S14). When it is determined in step S13 that the absolute value | A _s | of the slope A _s is smaller than the first predetermined value α, the process returns to step S11.

Subsequently, the control unit 20 determines whether or not the slope A _s reaches zero (A _s = 0) (step S15).

When it is determined in step S15 that A _s = 0 has been reached, the control unit 20 writes the output S _s2 of the first detection unit 12 and the time T _s2 at this time into the data collector 22 and stores the data (step S 15 S16), the process ends. When it is determined in step S15 that A _s = 0 has not been reached, step S15 is repeated.

  Next, the liquid adhesion determination process in the second detector 13 will be described based on FIG. FIG. 10 is a flowchart for explaining the liquid detection process of the present embodiment, and shows the flow of the liquid adhesion determination process in the second detection unit 13.

First, the control unit 20 acquires the output S _i and the time T _i of the second detection unit 13 (step S21).

Subsequently, the control unit 20 calculates the amount of change (gradient A _i ) in the output S _i of the second detection unit 13 with respect to the time T _i (step S22). The calculation method of the slope A _i may be, for example, the differential value of the output S _i of the second detection unit 13, or the change amount of the output S _i of the second detection unit 13 at two different times. .

Subsequently, the control unit 20 determines whether or not the absolute value | A _i | of the slope A _i is equal to or larger than the second predetermined value β (step S23). The second predetermined value β is the change in the output S _i of the second detector 13 when the liquid is not attached to the second detector 13 from the state where the liquid is attached to the second detector 13. It can be the absolute value of the quantity. The second predetermined value β is predetermined according to, for example, the material used for the second detection unit 13, the shape of the second detection unit 13, and the like.

When it is determined in step S23 that the absolute value | A _i | of the slope A _i is greater than or equal to the second predetermined value β, the control unit 20 controls the output S _i1 of the second detection unit 13 and the time T at this time. _i1 is written in the data collector 22 and stored (step S24). When it is determined in step S23 that the absolute value | A _i | of the slope A _i is smaller than the second predetermined value β, the process returns to step S21.

Subsequently, the control unit 20 determines whether or not the slope A _i has reached zero (A _i = 0) (step S25).

When it is determined in step S25 that A _i = 0 has been reached, the control unit 20 writes and stores the output S _i2 of the second detection unit 13 and the time T _{i2 at} this time in the data collector 22 ( In step S26), the process ends. When it is determined in step S25 that A _i = 0 has not been reached, step S25 is repeated.

  Next, the liquid attachment position calculation process will be described based on FIG. FIG. 11 is a flow chart for explaining the liquid detection processing of this embodiment and shows the flow of the liquid adhesion position calculation processing.

First, the control unit 20 calculates the output change amount in the first detection unit 12 and the second detection unit 13 when the liquid adheres to the liquid detection element 10 (step S31). Specifically, the control unit 20 uses the outputs S _s1 and S _s2 of the first detection unit 12 stored in the data collector 22 in steps S14 and S16 to perform liquid detection using the following equation (1). The output change amount V _A of the first detection unit 12 when the liquid adheres to the element 10 is calculated.
V _A = S _s1 −S _s2 (1)
Further, the control unit 20 uses the outputs S _i1 and S _i2 of the second detection unit 13 stored in the data collector 22 in steps S24 and S26 to determine the liquid detection element 10 by the following equation (2). The output change amount V _B of the second detector 13 when the liquid adheres is calculated.
V _B = S _i1 −S _i2 (2)
Subsequently, the control unit 20, the ratio of the output change amount V _B of the output variation of the first detection unit 12 V _A and the second detection unit 13 (hereinafter referred to as "the sensor output variation ratio R".) To calculate the (Step S32). Specifically, the control unit 20 calculates the sensor output change amount ratio R by the following equation (3).

R = V _B / V _A (3)
Subsequently, the control unit 20 calculates the liquid adhesion position X based on the sensor output change amount ratio R (step S33), and ends the process. Specifically, the control unit 20 calculates in step S32 using, for example, a map showing the relationship between the liquid adhesion position X on the first detection unit 12 and the sensor output change amount ratio R as shown in FIG. The liquid adhesion position X corresponding to the calculated sensor output change amount ratio R is specified, and the process ends. Note that FIG. 13 is a graph showing the relationship between the liquid adhesion position X and the sensor output change amount ratio R. When the liquid adheres to a predetermined position between the position X0 and the position X1 on the arrow X in FIG. Shows the sensor output change ratio R of.

  As described above, in the present embodiment, the liquid attachment position is calculated based on the output change amount of the first detection unit 12 and the output change amount of the second detection unit 13 when the liquid is attached. The position where the liquid adheres can be specified with high accuracy.

  Next, the correction amount calculation process in the first detection unit 12 will be described based on FIG. FIG. 12 is a flowchart for explaining the liquid detection processing of this embodiment, and shows the flow of the output correction processing in the first detection unit 12.

  First, the control unit 20 determines the output correction amount of the first detection unit 12 based on the liquid adhesion position X calculated in the liquid adhesion position calculation process (step S41). Specifically, using the map regarding the relationship between the liquid adhesion position X to the first detection unit 12 and the output correction amount (V) as shown in FIG. 14, the liquid adhesion position X corresponding to the liquid adhesion position X calculated in step S33 is used. Output correction amount (V) to be determined. Note that FIG. 14 is a graph showing the relationship between the liquid adhesion position X and the output correction amount of the first detection unit, and the liquid adheres to a predetermined position between the position X0 and the position X1 on the arrow X in FIG. The output correction amount of the first detection unit 12 at the time is shown.

  Subsequently, the control unit 20 corrects the output change amount of the first detection unit 12 by adding the output correction amount to the output change amount of the first detection unit 12 (step S42), and ends the process. Specifically, the control unit 20 adds the output correction amount calculated in step S41 to the output change amount of the first detection unit 12 at the liquid adhesion position X calculated in step S33 to perform the first detection. The output change amount of the unit 12 is corrected, and the process ends.

  The control unit 20 performs such liquid detection processing on a plurality of positions between the position X0 and the position X1 on the arrow X of FIG. The amount of change in the output of the detection unit 12 can be corrected.

  Specifically, as shown in FIG. 15, the output change amount that differs depending on the liquid attachment position X on the first detection unit 12 is changed by the liquid attachment position X on the first detection unit 12 as shown in FIG. Instead, it can be corrected to be substantially constant. Note that FIG. 15 is a graph showing the relationship between the liquid adhesion position X and the output change amount of the first detection unit, and the liquid is adhered to a predetermined position between the position X0 and the position X1 on the arrow X in FIG. The amount of change in the output of the first detection unit is shown. 16 is a graph showing the relationship between the liquid adhesion position and the output change amount of the first detection unit before and after the correction, and is shown at a predetermined position between the position X0 and the position X1 on the arrow X in FIG. The output change amount of the first detection unit 12 before and after the correction when the liquid adheres is shown. The circles in FIG. 16 indicate the output change amount of the first detection unit 12 before correction, and the triangle marks indicate the output change amount of the first detection unit 12 after correction.

  As described above, in the present embodiment, the output correction amount of the first detection unit 12 is determined according to the liquid adhesion position X calculated in the liquid adhesion position calculation process, and the output change of the first detection unit 12 is determined. The output change amount of the first detector 12 is corrected by adding the output correction amount to the amount. As a result, the liquid adhesion amount can be corrected according to the liquid adhesion position X, so that the liquid adhesion amount can be quantified with high accuracy.

  Although the liquid detection device has been described with reference to the embodiments, the present invention is not limited to the above embodiments, and various modifications and improvements can be made within the scope of the present invention.

10 Liquid Detection Element 11 Insulating Substrate 12 First Detection Section 13 Second Detection Section 20 Control Section 21 Computer 22 Data Collector 23 Circuit

Claims (1)

A liquid detection device for detecting a liquid adhesion position and an adhesion amount,
An insulating substrate,
A first detection unit provided on the surface of the insulating substrate, the first detection unit including a plurality of resistors each having a resistance value that changes according to a temperature change;
A second detection unit provided on a side surface of the insulating substrate, the second detection unit including a plurality of resistors each having a resistance value that changes according to a temperature change;
A droplet holding layer formed so as to cover the first detection unit and the second detection unit;
The liquid adhesion position is calculated based on the variation amount of the resistance value of the first detection unit and the variation amount of the resistance value of the second detection unit when the liquid is attached, and the liquid adhesion position is calculated according to the attachment position. A liquid detection device having a control unit that corrects the adhered amount.

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