JP5336790B2 - Sensor circuit and high-pressure water injection device - Google Patents

Description

  The present invention relates to a sensor circuit capable of reliably detecting drought even when using water containing foreign matter such as mud, sand and stone, and high-pressure water capable of reliably detecting drought and stopping driving. The present invention relates to an injection device.

  There is known a high-pressure water injection device that injects water, which is pressurized by a high-pressure pump, from an injection nozzle. In the high-pressure water injection device, the high-pressure pump is driven by the drive device, but if the high-pressure pump motor is driven during drought, it may cause damage or failure. Therefore, the drive device is provided with a sensor for detecting a drought state. . The driving device is stopped based on a drought detection signal from the sensor, and so-called idling is prevented.

  As a sensor for detecting the drought, for example, a pressure sensor, a paddle type sensor, a water level sensor, an area flow meter sensor, and the like are known, and such a sensor is provided on the inflow side or the outflow side of the high-pressure pump. It was like that.

  Among the high-pressure water jetting devices that have an idling prevention function, a type that supplies tap water by connecting to a high-pressure pump and water, for example, mud and sand that are used in civil engineering work sites and are not fresh water such as tap water For example, muddy water containing stones (hereinafter collectively referred to as foreign materials) can be used. Hereinafter, water that is not tap water and contains foreign substances will be collectively referred to as muddy water.

  When muddy water is used, of the above sensors, the water level sensor is a movable part of the float, the paddle type sensor is a movable part of the paddle, and the movable part becomes inoperable, while the pressure sensor is provided with a diaphragm. There is a problem that the foreign matter is clogged in the hole, and the area flow meter sensor has a foreign matter clogged in the flow rate measurement part, which makes it impossible to detect drought or cause erroneous detection.

  Therefore, instead of using the above-described measurement type sensors such as water level and flow rate as a means of detecting drought in a high-pressure water injection device having a function of preventing idling, an electric current such as current value and capacitance during drought is used. The following Patent Documents 1 to 3 propose to use a sensor circuit that detects a mechanical change.

Japanese Patent Laid-Open No. 2002-257077 Japanese Patent Laid-Open No. 2005-220895 JP 2007-315367 A

  Patent Document 1 is connected to a drive circuit of a motor of a high-pressure pump, monitors the operating current of the high-pressure pump, and determines that the water is drought when the current value is lower than the current value during normal operation. Yes.

  Patent Documents 2 and 3 are configured to include a capacitance determination circuit that detects a capacitance according to a change in water level of a circuit formed through water. In this capacitance determination circuit, a conductor covered with an insulator is electrically connected via a detection unit switching circuit, and a metal tip electrically connected to the conductor is connected to a water storage container. It is formed by providing at least two places.

  However, in Patent Document 1, foreign matter contained in muddy water is accumulated or bitten between the impeller and the casing, and thus there is a possibility of causing a malfunction that the motor load increases and does not stop even in a drought state. In addition, since the muddy water has a higher load on the motor than the tap water, there is a possibility that the motor load decreases and stops when a clear water is suddenly supplied from the muddy water.

  In Patent Documents 2 and 3, a foreign substance is clogged between the conductor and the tip part which are conducted by water at the tip part, and it may be in a conduction state even during drought and may cause a malfunction. In addition, if the water quality changes due to foreign matter accumulated in the water storage container, the relative permittivity changes, which may cause a malfunction.

  The problem to be solved by the present invention is that, in Patent Document 1, the motor current value fluctuates due to a factor other than drought, and in Patent Documents 2 and 3, when a foreign object is clogged between the conductor and the tip portion, it becomes conductive. In addition, since the relative permittivity changes due to the change in water quality due to turbidity of foreign matter, accurate drought cannot be detected.

In order to solve the above problems, the sensor circuit of the present invention, water from the pole among exposed by projecting into the inclined portion of the connection tube having an inclined portion and a vertical portion for supplying the water source, one end Is connected to the power source via the inner pole resistance R1, and the other end is grounded via the outer pole resistance R2 which is the sum of the resistance Ra of the water in the connection pipe and the resistance Rb of the connection pipe. When the divided output of the outer electrode resistance R2 is connected to a comparator and the outer electrode resistance R2 becomes infinite, 1 / {(inner electrode resistance R1 / outer electrode resistance R2) in relation to the inner electrode resistance R1. When +1} ≈1, the drought was detected .

In addition, the high-pressure water injection device of the present invention has an inclined portion and a vertical portion so as to supply water to the high-pressure pump, one end toward the high-pressure pump, the other end toward the water inflow side, and the other end toward the one end. One end is connected to the power source through the inner pole resistor R1 and the other end from the connecting pipe connected by providing a drop by the section and the exposed inner pole protruding into the inclined portion on the water inflow side of the connecting pipe There is grounded through the outer pole resistor R2 is the sum of the resistance Rb of the resistor Ra and the connecting pipe of the water connection pipe, connecting the divided output of the internal electrode resistance R1 and the outer electrode resistor R2 to the comparator, outside When the pole resistance R2 becomes infinite, it is detected as drought when 1 / {(inner pole resistance R1 / outer pole resistance R2) +1} ≈1 in relation to the inner pole resistance R1, and this comparator And a sensor circuit for providing the output to the driving device.

  Since the sensor circuit according to the present invention does not detect the load of the motor, that is, the current value as in Patent Document 1, the sensor circuit is not affected by the specific gravity of the muddy water or the foreign matter contained in the muddy water. Since the electrostatic capacity is not detected as described above, it is not affected by the moisture remaining between the conductor and the tip portion or the water quality of the foreign matter, so that the drought state can be reliably detected without malfunction.

That is, the sensor circuit of the present invention, the inner electrode is exposed in the inclined portion of the connection tube, has no outer pole in the vicinity of the inner electrode. Therefore, since there is no situation where the foreign matter is clogged with the outer pole, stable drought detection is possible even when muddy water is used.

In the sensor circuit of the present invention, instead of having the outer pole in the vicinity of the inner pole, the outer pole resistance R2 and the ground point are made to function as the outer pole on the circuit. In this way, the (mud) divided output when water is present in the connection pipe, the outer pole resistors R2 / (inner electrode resistance R1 + outer pole resistor R2).

The outer electrode resistance R2 is, for example, the sum of the resistance value of water, the resistance value of the connecting pipe , and the like, and the resistance value of water among the above is involved in the fluctuation of the outer electrode resistance R2. That is, when the inner pole resistance R1 is fixed, the variable element becomes the outer pole resistance R2. Here, the inner pole resistance R1 is fixed to a resistance value that does not greatly depend on the fluctuation even if the outer pole resistance R2 fluctuates.

  In order to function as a sensor, the following conditions may be satisfied. When detecting drought, when the outer pole resistance R2 becomes infinite, 1 / {(inner pole resistance R1 / outer pole resistance R2) +1} ≈1 in relation to the inner pole resistance R1. Good.

That is, the inner electrode resistor R1, for example, at least when the resistance value when tap water (the inner electrode resistor R1 close to 0) to, even if there is water in the outer pole resistance in the connecting pipe regardless of the value of R2 drought When the inner pole resistance R1 is made close to infinity, drought is not detected regardless of the value of the outer pole resistance R2.

That is, the sensor circuit of the present invention sets the inner pole resistance R1 to an appropriate value, so that the drought detection point is appropriately set between the drought state and the other state within the fluctuation range of the outer pole resistance R2. be able to. Thus, the sensor circuit of the present invention, the presence of water in the connecting pipe, be varied outer electrode resistor R2 by water, by the inner pole resistors R1, or drought or not within the variation range of the outer pole resistor R2 Since it detects, false detection is prevented.

The high-pressure water injection device of the present invention uses the sensor circuit of the present invention, and the inner pole of the sensor circuit is directed from the other end connected to the water inflow side to one end connected to the high-pressure pump side. Since it is provided inside the water inflow side of the connecting pipe connected with a drop by the inclined part and the vertical part , unnecessary moisture that induces false detection flows quickly from the vicinity of the inner pole due to the inclination of the connecting pipe. (Removed), it is possible to reliably detect drought only during true drought.

  The present invention can be implemented in the forms shown in FIGS. 1-3 is a figure which shows the sensor circuit and high pressure water injection apparatus of this invention. As shown in FIG. 1, the high-pressure water injection device 1 of the present invention is configured to inject water, which is pressurized by a high-pressure pump 3 driven by a drive device 2, from an injection nozzle 4 through a hose h. ing.

  The high-pressure water injection device 1 includes a water source 5 for supplying water to the high-pressure pump 3. In this example, the water source 5 is provided with a water storage container, which means this. However, the water storage container is omitted, the intake pipe P is connected to a water supply or a river, and the connection destination of the intake pipe P is meant. It doesn't matter.

  Further, the high-pressure water injection device 1 is provided with a connection pipe 6 for supplying water from the water source 5 to the high-pressure pump 3, and the sensor circuit 7 of the present invention for detecting drought is electrically connected to the connection pipe 6. Has been.

  The connecting pipe 6 is configured as shown in FIG. The connecting pipe 6 employs an insulating resin pipe H, and as shown in FIG. 2A, in this example, the connecting end 6a connected to the bottom of the water source 5 which is a water storage container is provided. A vertical portion α having an elevation difference of 25 cm or more is formed with the connection end 6b connected to the high-pressure pump 3 as the upper side and the lower side as the lower side. In this example, the vertical portion α of the connection end 6a and the connection end 6b is, for example, 30 cm in this example.

  In addition, an inclined portion β having a height difference of 1 cm or more is formed on the connecting end 6a side up to the vertical portion α of the connecting pipe 6 on the connecting end 6b side, that is, on the high pressure pump 3 side. Has been. In this example, it is 2.5 cm, for example. On the other hand, a portion from the vertical portion α of the connection pipe 6 to the connection end 6b (up to the high pressure pump 3) is provided with a normal elbow and is horizontal.

  Further, a sensor case C having an inner pole 7 </ b> A in the sensor circuit 7 is provided on the inclined portion β of the connection pipe 6. As shown in FIG. 2 (b), the sensor case C is attached at an inclined portion β in the range of −90 ° to 90 ° with respect to the axial center of the connecting pipe 6 at the axis center. In this example, the sensor case C is at a position of −45 ° (45 ° from the horizontal position).

  As shown in FIG. 3, in the sensor case C, the casing C1 is made of an insulating resin, and the inside thereof is filled with an insulating portion C2 made of a resin material. The inner pole 7A is provided so as to protrude from the center of the insulating portion C2 toward the liquid level inside the connecting pipe 6.

  With reference to FIG. 3, the sensor circuit 7 of the present invention will be described focusing on the inner pole 7A. One end of the inner pole 7A is connected to the power source via the inner pole resistance R1, and the other end is grounded via the outer pole resistance R2. The inner pole resistance R1 is fixed in the range of 100 KΩ to 100 MΩ. In this example, the inner pole resistance R1 is 1 MΩ. The outer pole resistance R2 corresponds to the resistance Ra of water when water is present, and the resistance Rb of the connection pipe 6 when drought occurs.

  Then, the inner pole resistance R1 and the outer pole resistance R2 are resistance-divided, and this divided voltage value is output to the comparator 7B. The comparator 7B compares the divided voltage value with the reference voltage value, and outputs a signal to that effect (a drought signal) to the stop circuit 7C when the reference voltage value is exceeded. The stop circuit 7 </ b> C generates a stop signal based on the drought signal and outputs it to the drive device 2. The driving device 2 stops driving based on a stop signal from the stop circuit 7C.

  According to the high pressure water injection device 1 and the sensor circuit 7 of the present example, first, the connecting pipe 6 is provided with the vertical portion α and the inclined portion β, so that water from the water source 5 does not stay in the vicinity of the inner pole 7A. Therefore, erroneous detection that the water source 5 is not drought in spite of the drought state is prevented.

  Further, the inner pole 7A protrudes toward the liquid surface in the connecting pipe 6 at the inclined portion β in the range of −90 ° to 90 ° at the center of the axis from the upper orthogonal position of the axis of the connecting pipe 6. Therefore, the inner pole 7A is well drained, and the erroneous detection can be prevented as described above.

  Further, since the sensor circuit 7 is configured to be grounded from the power source via the inner pole resistance R1, the inner pole 7A, and the outer pole resistance R2, is the outer pole resistance R2 present when water is present (water resistance Ra)? Since it is easy to determine whether it is drought (resistance R2 of the connecting pipe 6), false detection can be reduced. That is, in the sensor circuit 7, although the outer pole resistance R2 fluctuates, the inner pole resistance R1 that assumes this fluctuation range is provided in advance to output this divided value, so that erroneous detection can be prevented. it can.

  Hereinafter, the results of experiments on the high-pressure water injection device 1 according to the present invention and the sensor circuit 7 according to the present invention will be described. In addition, in each experiment, also as a comparison object structure, each part name and reference code which were used for the high-pressure water-injection apparatus 1 of this invention and the sensor circuit 7 which concerns on this invention shown in the said FIGS. 1-3 are used. I will do it. Therefore, in the configuration to be compared, a configuration not included in the present invention is not given a reference symbol.

(Experiment 1): Sensor arrangement In Experiment 1, the material of the sensor case C, the material of the connecting pipe 6, and the arrangement of the sensor case C were set to the states A to D and A ′ to D ′, and humic soil was mixed therein. Muddy water was supplied and the sensor operation time was considered.

  The sensor used in A to D in Experiment 1 is provided with a conventional sensor, that is, an inner pole 7A and an outer pole. When water is present between the inner pole 7A and the outer pole, the sensor is conducted and no water is present. In this case, a normal so-called oil sensor that is in a non-conductive state (drought detection) was used. Hereinafter, it is referred to as “normal sensor”.

  The sensor used in A ′ to D ′ in Experiment 1 omits the outer pole in the conventional oil sensor, and instead has a configuration in which the outer pole is grounded via the sensor case C and the connecting pipe 6 (the present invention). The sensor circuit having a configuration without the internal resistance R1 is used. Hereinafter, it is referred to as “body earth sensor”.

(A and A ')
The connection pipe 6 was made of “metal” and the connection was “horizontal”. The sensor case C was made of “metal” teeth, and the straight part was connected to the connecting pipe 6 so that the orthogonal part was in the upper orthogonal position.
(B and B ')
The connection pipe 6 was made of “metal” and the connection was “horizontal”. The sensor case C was made of “resin” tees, and the straight part was connected to the connecting pipe 6 so that the orthogonal part was in the upper orthogonal position.

(C and C ′)
The connection pipe 6 was made of “resin” and the connection was “horizontal”. The sensor case C was made of “resin” tees, and the straight part was connected to the connecting pipe 6 so that the orthogonal part was in the upper orthogonal position.
(D and D ')
The connecting pipe 6 is made of “resin”, the connection is provided with a vertical difference α of 30 cm in height and the inclination difference of the inclined portion β is 2.5 cm. The sensor case C is made of “resin” linear, The connection pipe 6 was connected at 0 ° (upper orthogonal position) from the upper orthogonal position of the axis of the connecting pipe 6.

  The result was that A stopped working with a supply of about 6 minutes (muddy water), i.e. no longer detected drought. B stopped working with a supply of about 5 minutes. C stopped working with a supply of about 4 minutes. D stopped working with a supply of about 5 minutes.

  A 'ceased to work with a (mud) supply for about 5 hours, i.e. no longer detected drought. B 'stopped working with a supply of about 4.5 hours. C 'stopped working with a supply of about 33.5 hours. D 'did not work after approximately 105 hours of supply.

  From this result, when the normal sensor is used, even if the material of the sensor case C, the material of the connection pipe 6 and the sensor case arrangement are changed to the states A to D, the muddy water is supplied, and the inner pole 7A When the foreign electrode is once clogged or adhered (as it is) to the conductive state, the proper detection cannot be maintained for more than 10 minutes.

  On the other hand, in the case of A ′ to D ′ using the body earth sensor, foreign matter is not clogged between the inner electrode 7A and the outer electrode as compared with the normal sensor, so that both are 20 hours compared to A to D. However, there is a case where foreign matter or moisture adheres to the connecting pipe 6 and the sensor case C, and the inner pole 7A is brought into a conductive state through the foreign matter or moisture.

  Summarizing Experiment 1, it was found that using a body earth sensor (A 'to D') is extremely effective in situations where muddy water is used. In addition, in A ′ to D ′, it was found that D ′ can stabilize the detection accuracy for a very long time because foreign matter and moisture do not stay in the inner electrode 7 </ b> A, the sensor case C, and the connecting pipe 6.

(Experiment 2): Sensor circuit Since the body earth sensor used in the experiment 1 did not employ the configuration of the present invention as a sensor circuit, from the above results, it was compared with others (A to D). Although detection for a long time was possible, finally, a foreign substance or moisture adhered to the connecting pipe 6 and the sensor case C, and this was brought into conduction with the inner pole 7A, thereby causing erroneous detection. Based on the above, in Experiment 2, the body earth sensor and the sensor circuit of the present invention were compared and considered.

  When the body earth sensor operates properly, when muddy water is present, the outer pole resistance R2 (muddy water resistance Ra and the resistance Rb of the connecting pipe 6) becomes a resistance of about 2k to 10kΩ and conducts, thus detecting drought. On the other hand, when no muddy water is present, the outer pole resistance R2 becomes larger than this, and a non-conductive state is detected.

  If the body earth sensor is to be operated properly without detection error, the outer pole resistance R2 may be set to a resistance value range that should be set to 2 k to 10 kΩ when (mud) water is present. Therefore, the body earth sensor detects drought when the output voltage Vout = {outer pole resistance R2 / (inner pole resistance R1 + outer pole resistance R2)} × Vin exceeds the reference voltage. .

  The case where the body earth sensor does not operate properly is when the drought is not detected when the (mud) water is not present, or when the drought is detected when the water is present. This is because foreign matter or moisture adheres to the connecting pipe 6 and the sensor case C and becomes conductive with the inner pole 7A. In the latter, the resistance value of the outer pole resistance R2 is set too low, and the water quality is low. This is due to the change in the resistance value Ra of the water due to the change and the length of the connecting pipe 6.

  Therefore, it is necessary to consider a resistance error that varies due to adhesion of foreign matter or moisture in an actual drought state and a resistance error that varies depending on a change in water quality. However, if the outer pole resistance R2 is increased in consideration of this resistance error, drought may be detected based on the water quality (Ra) despite the presence of water. On the other hand, when the outer electrode resistance R2 is set to be smaller than 2 k to 10 kΩ, naturally drought is not detected.

  Therefore, an inner pole resistance R1 is provided as in the sensor circuit 7 of the present invention, and the resistance is divided from the outer pole resistance R2, and this divided voltage is output to the comparator 7B. That is, in the configuration of the present invention, the output voltage Vout is {outer pole resistance R2 / (inner pole resistance R1 + outer pole resistance R2)} × Vin, and is affected by fluctuations in the outer pole resistance R2 (water resistance Ra). Disappear.

  Based on the above, in Experiment 2, an operation comparison between the body earth sensor and the sensor circuit 7 of the present invention was performed. In Experiment 2, when D ′ using the body earth sensor of Experiment 1 (Comparative Example) and when using the sensor circuit 7 of the present invention in D ′ of Experiment 1 (Example), Experiment 1 Thus, the sensor operating time was considered.

  As a result of Experiment 2, the comparative example did not operate in about 105 hours as in Experiment 1, but the example operated for over 105 hours. From this, it was found that the sensor circuit 7 of the present invention has extremely high reliability.

(Experiment 3): Numerical value setting The reason why the height difference of the vertical portion α is 25 cm or more is based on the following experiment 3-1. Experiment 3-1 confirmed the operational stability of the sensor circuit 7 in the case where the height difference of the vertical portion α was smaller than 25 cm in D ′ of Experiment 1 using the sensor circuit 7 of the present invention.

  If the height difference of the vertical part α is smaller than 25 cm, the sensor circuit 7 operates normally, but water does not flow quickly, so it takes more time to detect than the set operation, and during that time the high-pressure pump 3 is idling. . In addition, when the height difference of the vertical part α is larger than 35 cm, a height higher than necessary is required, and the entire high-pressure water injection device 1 is enlarged.

  The reason why the height difference of the inclined portion β is 1 cm or more is based on the following Experiment 3-2. Experiment 3-2 confirmed the operational stability of the sensor circuit 7 when the height difference of the inclined portion β was smaller than 1 cm in D ′ of Experiment 1 using the sensor circuit 7 of the present invention.

  If the height difference of the inclined portion β is smaller than 1 cm, the sensor circuit 7 operates normally, but water does not flow quickly, so detection may take longer than the set operation. When the detection time became longer, the high-pressure pump 3 was idled. In addition, if the height difference of the inclined part β is larger than 5 cm, an unnecessarily high height is required, and the entire high-pressure water injection device 1 is enlarged.

  The reason why the inclination angle of the sensor case C is in the range of −90 ° to 90 ° from the upper orthogonal position (0 °) of the inclined portion β of the connecting pipe 6 is based on the following Experiment 3-3. In Experiment 3-3, in D ′ of Experiment 1 using the sensor circuit 7 of the present invention, the inclination angle of the sensor case C is set to the lower orthogonal position of the axis of the inclined portion β of the connecting pipe 6 (that is, the upper orthogonal position is set to 0 °). The position of the sensor circuit 7 was appropriately changed in the range of −91 ° to 91 ° from the position of 180 ° in the case of the above, and the operational stability of the sensor circuit 7 was confirmed.

  When the inclination of the inclined portion β of the sensor case C is −91 ° to 91 °, moisture b and foreign matter remaining in the inclined portion β flows into the sensor case C, and near the inner pole 7A in the sensor case C. In some cases, moisture or foreign matter remains and drought is not detected.

  The reason why the inner resistance R1 is set to 100 KΩ to 100 MΩ is based on the following Experiment 3-4. In Experiment 3-4, the operational stability of the sensor circuit 7 was confirmed for the case where the inner pole resistance R1 was smaller than 100 KΩ and the case where it was larger than 100 MΩ.

  If the inner pole resistance R1 is smaller than 100 KΩ, it becomes close to the resistance value of water. Therefore, in the case of {outer pole resistance R2 / (inner pole resistance R1 + outer pole resistance R2)} × Vin, drought may be detected even when the water is full. there were. On the other hand, if the inner pole resistance R1 is larger than 100 MΩ, it becomes close to the resistance value of air. Therefore, there is a case where drought is not detected in {outer pole resistance R2 / (inner pole resistance R1 + outer pole resistance R2)} × Vin. It was.

  The sensor circuit of the present invention is particularly suitable for use in a high-pressure water injection device, but if it is used for a pumping device (device) in a civil engineering work site where, for example, muddy water is pumped, an unnecessary load is applied when pumping is completed. It can prevent giving to a pump.

It is a block diagram which shows schematic structure of the high pressure water injection apparatus of this invention. It is a figure which shows the piping condition in the high pressure water injection apparatus of this invention. It is a circuit diagram which shows roughly the sensor circuit of this invention in the high pressure water injection apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High pressure water injection apparatus 2 Drive apparatus 3 High pressure pump 4 Injection nozzle 5 Water source 6 Connection pipe 7 Sensor circuit 7A Inner pole 7B Comparator 7C Stop circuit C Sensor case C1 Case C2 Insulation part R1 Inner pole resistance R2 Outer pole resistance Ra Water Resistance Rb Connection tube resistance α Vertical part β Inclined part

Claims (3)

In the sensor circuit for detecting a drought, water from the pole among exposed by projecting into the inclined portion of the inclined portion and the connecting tube having a vertical portion for supplying the water source, through the inner pole resistor R1 and one end And the other end is grounded via an outer electrode resistance R2, which is the sum of the resistance Ra of the water in the connection pipe and the resistance Rb of the connection pipe, and the inner resistance R1 and the outer resistance R2. Is connected to a comparator, and when the outer electrode resistance R2 becomes infinite, 1 / {(inner resistance R1 / outer resistance R2) +1} ≈ in relation to the inner resistance R1 A sensor circuit that detects drought when 1 is satisfied . Sensor circuit according to claim 1, wherein the inner electrode resistor R1, wherein the 100KΩ~100MΩ der Turkey. In a high-pressure water injection device that injects water, which is pressurized by a high-pressure pump driven by a driving device, from an injection nozzle, one end is on the high-pressure pump side and the other end is on water to supply water to the high-pressure pump. From the connecting pipe connected to the inflow side from the other end toward the one end by a drop due to the inclined portion and the vertical portion, and from the exposed inner pole protruding into the inclined portion on the water inflow side of the connecting pipe , One end is connected to a power source via an inner pole resistance R1, and the other end is grounded via an outer pole resistance R2 which is the sum of the resistance Ra of the water in the connecting pipe and the resistance Rb of the connecting pipe, When the divided voltage output of the pole resistance R1 and the outer pole resistance R2 is connected to a comparator and the outer pole resistance R2 becomes infinite, 1 / {(inner pole resistance R1) in relation to the inner pole resistance R1. / External pole resistance R2) +1} ≒ 1 is detected as drought A sensor circuit for providing an output of the comparator to the driving device, high-pressure water-jet apparatus characterized by comprising a.

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