JP2008180531A - Distance-measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distance-measuring device capable of detecting an accurate water level, by comparing both the data by adopting a reception quantity (voltage) data other than distance data calculated, based on the time until a reflected wave returns, when detecting a full state of drain water stored in a drain water receiver, by using an ultrasonic sensor as a water level sensor. <P>SOLUTION: This distance-measuring device for measuring a distance by using as a measuring medium, ultrasonic waves, emitted from the ultrasonic sensor used as the water level sensor 5, are provided with a means for outputting a distance based on the time until the received waves are measured, and a means for outputting the quantity received. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a distance measuring device used as, for example, a drain water detecting device for a freezer / refrigerated showcase.

  As shown in FIG. 13, an open type vertical refrigerated showcase installed in a store such as a supermarket is composed of a condenser 2 and a compressor in a machine room 3 formed at the bottom of the showcase body. A refrigeration apparatus is provided to cool the product stored in the product storage 1 with the cool air cooled by the cooler installed on the back side of the showcase body, and the cool air is circulated. In the figure, 6 is a condenser fan, and 7 is an evaporation plate.

  As described above, the cool air is circulated in the cabinet, but since the front surface of the product storage 1 is opened as a product entrance, warm outside air flows from here, and moisture contained therein is Condensation occurs in the cooler and forms frost

  And in order to prevent that the capacity | capacitance of a cooler falls by this frost formation, although it defrosts suitably, the defrosted water | moisture content generate | occur | produces as drain water.

  The drain water is usually connected to a drain pipe and led to a drain groove outside the store by this pipe. When the pipe is connected, the installation position of the showcase is fixed by this pipe. Therefore, in a showcase in which a compressor is incorporated for easy movement, drain water is also stored in a drain water receiver 4 such as a drain pan or drain tank installed in the showcase so as not to impair mobility. .

  In this way, when drain water is stored in the drain water receiver 4, it is necessary to drain the water regularly. However, the amount of drain water generated depends on the weather, the size and temperature range of the showcase, It depends on the amount.

As a method for detecting the fullness of drain water, there is a method of using an ultrasonic sensor as a water level sensor. A water level sensor 5 is installed above the drain water receiver 4 and the ultrasonic wave transmitted from here toward the water surface is applied to the water surface. The time from reflection to reception is measured to measure the distance between the water level sensor 5 and the water surface, that is, the water level (see, for example, Patent Document 1).
JP 2001-59765 A

  As shown in FIGS. 15 and 16, the method of using the ultrasonic sensor is a pulse transmitted from a transmission circuit unit 12 that is a pulse oscillation unit that controls the water level sensor sound wave oscillation unit 11 of the ultrasonic sensor that is the water level sensor 5. The time until the signal is reflected on the water surface and returns to the receiving circuit unit 13 is measured, and the arithmetic processing circuit unit 14 calculates the distance between the water level sensor 5 and the water surface based on this time, that is, the water level. The circuit unit 13 is connected to the showcase controller 8.

  In general, in order to extend the measurement distance in an ultrasonic sensor, it is necessary to increase the sound pressure by raising the input to the ultrasonic oscillation element in consideration of the attenuation of the ultrasonic signal. In order to reduce the influence of the transmission waveform, it is necessary to lower the sound pressure so that the reception waveform does not overlap the transmission waveform. Nevertheless, at a frequency of 20 KHz that can be normally used with a PZT element, the noise and stability of the drive voltage affect the accuracy, making it impossible to accurately measure 70 mm or less.

  As shown in FIG. 17, the distance over which the received waveform overlaps the transmitted waveform is actually about 80 mm, and the distance at which reception cannot be confirmed due to attenuation of the received waveform is about 200 mm. Thereby, it can be seen that the range that can be normally measured is 80 mm or more.

  FIG. 14 is a front view showing an example of the relationship with the drain water receiver 4 when an ultrasonic sensor is used as the water level sensor 5. The height of the machine room 3 is 300 mm as an example, and the water level described in FIG. The range in which the distance can be normally measured by the sensor 5 can be secured. The water level sensor 5 and the drain water receiver 4 are disposed within this limited height range of the machine room 3, and the drain water receiver 4 has a height in order to secure a distance from the water level sensor 5. As a low one (shallow depth), for example, about 40 mm.

  Then, with the lip of the drain water receiver 4 as a limit level, the distance between the limit level and the ultrasonic wave transmitting / receiving element 10 of the water level sensor 5 is 70 mm which is the minimum value within the range in which the water level sensor 5 can normally measure. And the full water level is set 10 mm below this limit level.

  As a result, the full water level is located at a height of 80 mm away from the transmitter of the water level sensor 5, and the full water level can be reliably positioned within the normal measurable range, and 10 mm until the drain water overflows from the drain water receiver 4. The full water level is reported at this full water level.

  As described above, ultrasonic waves are used as a method for measuring the water level, the time from when this ultrasonic wave is transmitted until it returns is measured, this time is converted into a corresponding signal and output to the outside. In the case of the method that the controller receives and calculates the distance, if the water level sensor itself has a defect at the manufacturing stage, or if dust is attached to the water level sensor, the mounting angle of the water level sensor was not normal Depending on various factors, the transmitted ultrasonic wave may not be received as a correct reflected wave.

  As a result, the water level cannot be measured accurately, resulting in problems such as increased malfunction due to disturbance and a reduced detection distance range as shown in FIG.

  Also, when outputting data as distance, it is not possible to determine whether the correct reflected wave is actually received, and furthermore, the water level sensor itself is the reason why the water level cannot be detected accurately, or it was in the work of installing the water level sensor However, it was difficult to obtain an appropriate coping method.

  The object of the present invention is to eliminate the inconvenience of the conventional example, and adopt data other than the distance data when detecting the full water of the drain water stored in the drain water receiver using the ultrasonic sensor as the water level sensor. It is an object of the present invention to provide a distance measuring device capable of detecting an accurate water level by detecting.

  In order to achieve the above object, the present invention provides a distance measuring device that measures a distance using an ultrasonic wave transmitted from an ultrasonic sensor as a water level sensor as a measurement medium. It is characterized in that means for outputting the distance based on the time until it is done and means for outputting the received amount are provided.

  As described above, the distance measuring device of the present invention has a time until the received wave is measured when detecting the fullness of the drain water stored in the drain water receiver using the ultrasonic sensor as the water level sensor. In addition to the distance data calculated as described above, it is possible to detect the accurate water level by using the received wave amount data and detecting the water level from both data.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a control block diagram of a first embodiment of the distance measuring device of the present invention, FIG. 2 is a perspective view of the water level sensor, and the entire configuration of the showcase in which the present invention is implemented is the same as the conventional example described with reference to FIG. Since they are the same, the same reference numerals are attached and detailed description thereof is omitted here.

  The distance measuring device according to the present invention is a water level sensor 5 using an ultrasonic sensor, which includes an ultrasonic transmission / reception element 10 and a control unit 17, and is connected to the output side of the control unit 17 via an ultrasonic transmission circuit 15. The ultrasonic wave transmitting / receiving element 10 is connected, and the ultrasonic wave transmitting / receiving element 10 is connected to the input side via the ultrasonic receiving circuit 16.

  Further, a distance numerical value output and a received peak value output from the control unit 17 are output to the connector 18 attached to the water level sensor 5. In FIG. 2, reference numeral 18a denotes a sensor power source, 18b denotes a distance numerical signal output, and 18c denotes a received peak value signal output.

  Thereby, when the ultrasonic wave transmitted from the ultrasonic wave transmitting / receiving element 10 toward the water surface of the drain water in the drain water receiver 4 is reflected on the water surface and returned to the ultrasonic transmitting / receiving element 10, The time from when the signal is transmitted through the ultrasonic receiving circuit 16 to when it is received is input to the control unit 17, and the control unit 17 outputs the distance data based on the time and the signal output of the distance numerical information of the connector 18. 18b, and the reception amount (voltage) of the received wave is output to the signal output 18c of the received wave height value.

  Thus, the received wave is not only converted into distance data but also converted into voltage. In this case, as the distance increases, the voltage value (received peak value) decreases and decreases as it returns. Therefore, the distance data converted and output to the signal output 18b is compared with the received peak value output to the signal output 18c, and if there is consistency, both data are determined to be correct, and the mounting position of the water level sensor 5 is determined. Is determined to be normal.

  3 and 4 show the second embodiment, and the basic configuration is the same as that of the first embodiment, but the output side of the control unit 17 that outputs the distance numerical value output and the received peak value output and the connector 18 are shown. An output changeover circuit 19 is interposed therebetween, and a changeover switch 20 is connected to the output changeover circuit 19.

  The connector 18 attached to the case of the water level sensor 5 is provided with a signal output 18d for outputting a signal selected from either a distance numerical value output or a received peak value output.

  The selector switch 20 includes a distance output switch 20a and a peak value output switch 20b.

  Therefore, when determining the mounting position of the water level sensor 5 and the like, if the distance switch 20a is turned on by operating the changeover switch 20, the distance numerical value is output, and if the peak value output switch 20b is turned on, the HL output is output. When the distance is 100 mm or less, 0 V is output, and when the distance is 100 mm or more, 5 V is output.

  FIG. 5 and FIG. 6 show a third embodiment, and a setting is made so that the numerical value output and the peak value output are alternately output from the control unit 17 to the connector 18. The distance numerical value output and the peak value output are not output at the same time, and even if they are output alternately, it is sufficient for comparison, and there is no shortage of information to be provided to a service person or the like.

  7 and 8 show a fourth embodiment, in which the showcase controller 8 is provided with a connector 21 for connecting a water level sensor, and the showcase controller 8 and the water level sensor 5 are connected. Then, according to the output switching request signal output from the showcase controller 8 side to the water level sensor 5, the control unit 17 of the water level sensor 5 outputs either a distance output or a peak value output to the showcase controller 8.

  As a result, a serviceman or the like can operate the showcase controller 8 to know either the distance data or the crest value, when obtaining the desired data. In this case, it is not necessary to attach the changeover switch as in the second embodiment to the water level sensor 5.

  9 and 10 show the fifth embodiment, and the basic configuration is that either distance output or peak value output is output via the connector 18 as in the fourth embodiment, but the constant configuration immediately after turning on the power is constant. Only the peak value data is output from the water level sensor 5 to the showcase controller 8 within the time, for example, for 4 seconds.

  Thereby, the voltage before being A / D converted into distance data and digitally displayed can be directly known as peak value data, and data accuracy can be improved.

  FIG. 11 and FIG. 12 show a sixth embodiment, which is a method for setting a range of distance that is determined to be normal when measuring the distance between the water surface of the drain water and the water level sensor 5. A normal range measurement method for the flow church of FIG. 11 will be described.

  When the drain water surface distance measurement mode is set (step 1) and the power is turned on, the voltage of the received waveform received by the water level sensor 5 was within the normal range when compared with the calculated distance data. When (step 2), a gain correction coefficient is calculated (step 3).

  Gain correction coefficient = received waveform voltage / distance−voltage characteristic center value, and using the gain correction coefficient obtained in this way, the normal drain water surface distance is then measured (step 4).

  In the water surface distance measurement using the gain correction coefficient, as shown in the graph of FIG. 12, the normal range is normal not only by the distance by the voltage characteristic center value but also by a certain width before and after the normal value. The normal limit was set.

  If it is determined in the stage of (Step 2) that it is not in the normal range, it is determined that the water level sensor is abnormal and a distance abnormality determination signal is output (Step 5).

  As an output of the distance abnormality determination, for example, an LED lamp for abnormality alarm is attached to the main body of the water level sensor 5, a dedicated output line is provided for the water level sensor 5, a sensor abnormality code is assigned to the data list of distance information, and Various methods such as outputting a code are conceivable, and the method is selected according to the needs of the user.

  The abnormality determination by the self-determination of the showcase controller 8 may be performed every measurement, but a filter function for preventing disturbance on software may be provided.

It is a control block diagram which shows 1st Embodiment of the distance measuring device of this invention. It is a perspective view of the water level sensor which shows 1st Embodiment of the distance measuring device of this invention. It is a control block diagram which shows 2nd Embodiment of the distance measuring device of this invention. It is a perspective view of the water level sensor which shows 2nd Embodiment of the distance measuring device of this invention. It is a control block diagram which shows 3rd Embodiment of the distance measuring device of this invention. It is an output figure which shows 3 embodiment of the distance measuring apparatus of this invention. It is a control block diagram which shows 4th Embodiment of the distance measuring device of this invention. It is an output figure showing a 4th embodiment of a distance measuring device of the present invention. It is a control block diagram which shows 5th Embodiment of the distance measuring device of this invention. It is an output figure showing a 5th embodiment of a distance measuring device of the present invention. It is a flowchart of the distance measurement operation | movement which shows 6th Embodiment of the distance measurement apparatus of this invention. It is a graph which shows the distance of the normal range which shows 6th Embodiment of the distance measuring device of this invention. It is a perspective view of the freezer / refrigeration showcase provided with the drain water detection apparatus. It is a front view of a drain water detection apparatus. It is a control block diagram of a water level sensor. It is a wave form diagram of a water level sensor. It is a graph which shows the measurable range by a water level sensor. It is a graph which shows the relationship between the peak value of a received waveform, and distance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Commodity storage 2 Condenser 3 Machine room 4 Drain water receptacle 5 Water level sensor 6 Condenser fan 7 Evaporating plate 8 Showcase controller 9 Full water warning lamp 10 Ultrasonic transmitter / receiver 11 Water level sensor sound wave generator 12 Transmitter circuit unit DESCRIPTION OF SYMBOLS 13 Reception circuit part 14 Arithmetic processing circuit part 15 Ultrasonic transmission circuit 16 Ultrasonic reception circuit 17 Control part 18 Connector 18a Sensor power supply 18b, 18c, 18d Signal output 19 Output switching circuit 20 Changeover switch 20a, 20b Switch 21 Water level sensor connection connector

Claims (7)

  In a distance measuring device for measuring a distance using an ultrasonic wave transmitted from an ultrasonic sensor as a water level sensor as a measurement medium, means for outputting a distance based on a time until a received wave is measured, and a received amount And a distance measuring device.   2. The distance measuring device according to claim 1, wherein the output of the reception amount is performed by an external signal.   The received amount is output by inputting a signal to a distance information output unit.   2. The distance measuring device according to claim 1, wherein the reception amount is output within a predetermined time immediately after the power is turned on.   In a distance measuring device that measures the distance using ultrasonic waves transmitted from an ultrasonic sensor as a water level sensor, the measured distance data is compared with the received data of the received wave. In this case, the distance measuring device comprises means for self-determining that it is abnormal.   In a distance measurement device that measures distance using ultrasonic waves transmitted from an ultrasonic sensor as a water level sensor, the distance data measured under specified conditions is compared with the sensitivity of the received wave data. And a distance measuring device comprising means for determining a correction value for the received amount.   The distance measuring device according to claim 6, wherein the correction value of the reception amount notifies the value to the outside.

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