Automatic exhaust device for water pump

Abstract

The present invention discloses an automatic exhaust device for a water pump, which specifically comprises an exhaust valve, a first connecting piece, a second connecting piece, a liquid level sensor and a controller. Through the technical solution, the operating condition of the water pump can be further monitored, and the risk of damage to the device caused by gas accumulation can be further effectively reduced. In addition, the automatic exhaust device also has the advantages of high automation, reliable performance, simple structure, easy assembly and easy promotion.

Description

Technical Field

[0001] The invention relates to the field of water equipment accessories, and in particular to an automatic exhaust device for a water pump. Background Art

[0002] During the use of the water pump, gas accumulation is one of the main factors that may affect the working condition of the water pump: due to the presence of gas in the pipe network system, the water flow will carry the water pump body, causing cavitation and damage; when the gas is in the water pump zone, it may also burn the mechanical seal, causing the water pump to leak, etc. It can be seen that gas accumulation has a great harm to the working condition of the water pump.

[0003] At present, the commonly used function is to install an automatic air intake and exhaust valve on the water inlet pipe section of the water pump, and automatically open the air intake and exhaust valve to exhaust gas when the gas pressure exceeds the preset threshold of the air intake and exhaust valve. However, there is a large error in the detection of gas accumulation by relying solely on the air intake and exhaust valve; at the same time, when the exhaust speed of the air intake and exhaust valve is lower than the gas accumulation speed, it is still easy to damage the water pump, so a safer, more effective and simple exhaust structure is urgently needed to be set in each water pump device. Summary of the invention

[0004] In view of the above problems existing in the prior art, an automatic exhaust device for a water pump is now provided, and the specific technical solution is as follows:

[0005] An automatic exhaust device for a water pump is applied to a water pump. The water pump comprises an exhaust port and a control cabinet. The control cabinet is used to control the operating condition of the water pump. The automatic exhaust device for the water pump is arranged at the exhaust port, and specifically comprises:

[0006] an exhaust valve, comprising an air intake hole and an air exhaust hole, for exhausting the gas in the water pump;

[0007] A first connecting member, comprising a main pipe and a branch pipe connected to the main pipe, one end of the main pipe being connected to the air intake hole through a first connecting pipe;

[0008] a second connecting member, one end of which is connected to the exhaust port, and the other end of which is connected to the other end of the main pipe via a second connecting pipe;

[0009] A liquid level sensor connected to the branch pipe, used to detect whether the liquid level in the main pipe reaches a preset liquid level and output a corresponding detection electrical signal;

[0010] A controller is arranged in the control cabinet and electrically connected to the liquid level sensor and the exhaust valve. According to the detected electrical signal, when the liquid level in the main pipe does not reach the preset liquid level, the exhaust valve is controlled to continue the exhaust work and the water pump is controlled to stop working.

[0011] Preferably, in the automatic exhaust device for a water pump, the exhaust valve is an automatic exhaust valve;

[0012] The automatic exhaust valve is preset with a pressure threshold. When the internal gas pressure of the water pump exceeds the preset pressure threshold, the automatic exhaust valve starts to work.

[0013] Preferably, in the automatic exhaust device for water pump, the exhaust valve is an electrically controlled exhaust valve;

[0014] The electronically controlled exhaust valve operates according to the control signal of the controller.

[0015] Preferably, the automatic exhaust device for a water pump further comprises a first pressure sensor and a second pressure sensor;

[0016] The first pressure sensor is arranged inside the water pump and electrically connected to the control end, and is used to detect the water inlet pressure of the water pump and output the water inlet pressure value;

[0017] The second pressure sensor is arranged inside the water pump and electrically connected to the control end, and is used to detect the outlet water pressure of the water pump and output the outlet water pressure value;

[0018] The controller controls the exhaust valve to continue exhausting and the water pump to stop working according to the detection electrical signal, water inlet pressure value and water outlet pressure value, when the liquid level in the main pipe does not reach the preset liquid level, the water inlet pressure value is not zero, and the water outlet pressure value is zero.

[0019] Preferably, in the automatic exhaust device for a water pump, the first connecting pipe comprises a DN15 monofilament head and a short tube, one end of the DN15 monofilament head is fixedly connected to one end of the short tube, and the other end of the DN15 monofilament head is fixedly connected to the suction hole by a threaded connection.

[0020] Preferably, in the automatic exhaust device for a water pump, the second connecting pipe comprises a first oblique pipe and a second oblique pipe;

[0021] One end of the first oblique tube is fixedly connected to the second connecting piece, and the other end of the first oblique tube has a wedge-shaped cross section;

[0022] One end of the second oblique tube is fixedly connected to the first connecting piece, and the other end of the second oblique tube matches and is fixedly connected to the other end of the first oblique tube.

[0023] Preferably, in the automatic exhaust device for a water pump, the second connecting pipe is a bendable sealing hose;

[0024] The first connecting member is fixed by an external bracket.

[0025] Preferably, in the automatic exhaust device for water pumps, a surface thread is provided near the front end of the liquid level sensor;

[0026] The inner wall of the branch pipe is provided with a thread matching the liquid level sensor, and the liquid level sensor and the branch pipe are fixedly connected by a threaded connection.

[0027] Preferably, in the automatic exhaust device for water pumps, the liquid level sensor is a photoelectric liquid level sensor, comprising a photoelectric detection device arranged at the front end of the liquid level sensor and an indicator light arranged at the rear end of the liquid level sensor;

[0028] The photoelectric detection device is electrically connected to the indicator light.

[0029] A control method for a water pump automatic exhaust device is applied to the aforementioned water pump automatic exhaust device and comprises:

[0030] Step A1: The liquid level sensor continuously detects the liquid level in the main pipe to determine whether the liquid level has reached a preset level:

[0031] If yes, return to step A1;

[0032] If not, go to step A2;

[0033] Step A2, the controller controls the water pump to stop working, and controls the exhaust valve to continue exhausting work until the liquid level sensor detects that the liquid level reaches a preset liquid level;

[0034] In step A3, the controller controls the water pump to work and returns to step A1.

[0035] A control method for a water pump automatic exhaust device is applied to the aforementioned preferred water pump automatic exhaust device and comprises:

[0036] Step B1, the liquid level sensor continuously detects the liquid level in the main pipe to determine whether the liquid level reaches a preset liquid level; and

[0037] The first pressure sensor and the second pressure sensor respectively continuously detect the water inlet pressure and the water outlet pressure of the water pump to determine whether the water inlet pressure value and the water outlet pressure value are zero:

[0038] If the liquid level reaches the preset liquid level and the water inlet pressure value is not zero and the water outlet pressure value is zero, go to step B2;

[0039] If the liquid level does not reach the preset liquid level, and / or the water inlet pressure value is zero, and / or the water outlet pressure value is not zero, return to step B1;

[0040] Step B2, the controller controls the water pump to stop working, and controls the exhaust valve to continue exhausting work until the liquid level sensor detects that the liquid level reaches a preset liquid level;

[0041] Step B3, the controller controls the water pump to work and returns to step B1.

[0042] This technical solution has the following advantages or beneficial effects:

[0043] Through this technical solution, it is possible to further monitor the operating conditions of the water pump, while further effectively reducing the risk of damage to the device due to gas accumulation. In addition, this type of automatic exhaust device also has the advantages of high degree of automation, reliable performance, simple structure, easy assembly and easy promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a structural schematic diagram of an automatic exhaust device for a water pump of the present invention;

[0045] Figure 2 The figure is an exploded view of an automatic exhaust device for a water pump according to the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0048] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0049] In view of the above problems existing in the prior art, an automatic exhaust device for a water pump is now provided, and the specific technical solution is as follows:

[0050] An automatic exhaust device for a water pump is applied to a water pump. The water pump comprises an exhaust port and a control cabinet. The control cabinet is used to control the operating conditions of the water pump. The automatic exhaust device for the water pump is arranged at the exhaust port. Figure 1-2 As shown, specifically including:

[0051] An exhaust valve 1, comprising an air intake hole 11 and an air exhaust hole 12, for exhausting the gas in the water pump;

[0052] A first connecting member 2, comprising a main pipe 21 and a branch pipe 22 connected to the main pipe 21, one end of the main pipe 21 is connected to the air intake hole 11 through a first connecting pipe 23;

[0053] a second connecting member 3, one end of which is connected to the exhaust port, and the other end of which is connected to the other end of the main pipe 21 through a second connecting pipe 31;

[0054] A liquid level sensor 4, connected to the branch pipe 22, for detecting whether the liquid level in the main pipe 21 reaches a preset liquid level, and outputting a corresponding detection electrical signal;

[0055] A controller 5 is arranged in the control cabinet and electrically connected to the liquid level sensor 4 and the exhaust valve 1. According to the detected electrical signal, when the liquid level in the main pipe 21 does not reach the preset liquid level, the exhaust valve 1 is controlled to continue the exhaust work and the water pump is controlled to stop working.

[0056] A specific embodiment is now provided to explain and illustrate the technical solution in detail:

[0057] In the first specific embodiment of the present invention, the automatic exhaust device of the water pump includes an exhaust valve 1, a first connecting piece 2, a second connecting piece 3, a liquid level sensor 4 and a controller 5, wherein the exhaust valve 1 is used to exhaust the gas accumulated in the water pump; the first connecting piece 2 is a welded tee, the main pipe 21 is arranged in parallel in the vertical direction, and the automatic exhaust valve 1 and the second connecting piece 3 are connected by the first connecting pipe 23 and the second connecting pipe 31 respectively, the branch pipe 22 is arranged vertically to the main pipe 21 and together with the main pipe 21, the liquid level sensor 4 is arranged through the branch pipe 22 to detect the water level in the main pipe 21 - when the water pump is operating normally, according to the setting position of the first connecting piece 2 The water level should exceed the detection surface of the liquid level sensor 4; and when the body in the water pump begins to gather and exceeds a certain safe working threshold, the liquid level in the main pipe 21 will drop accordingly. When the liquid level sensor 4 cannot detect the water level, it means that the gas in the water pump is in an excessive state. At this time, the liquid level sensor 4 sends a detection electrical signal (i.e., a switching signal) to the controller 5 arranged in the control cabinet. The controller 5 will make a judgment based on the detection electrical signal. When the liquid level in the main pipe 21 does not reach the detection surface of the liquid level sensor, the controller 5 sends a pump stop instruction to the water pump and controls the exhaust pump 1 to continue to maintain the exhaust working state. In this way, automatic detection and control of the water pump working condition can be realized.

[0058] In the first specific embodiment, the detectable surface of the liquid level sensor 4 is the preset liquid level. Before setting the automatic exhaust device of the water pump, it is necessary to detect and determine the setting height of the first connecting member 2 in advance. Figure 1-2 As shown, the setting height of the first connecting member 2 corresponds to the height of the horizontal liquid level that can be detected by the liquid level sensor 4. In particular, the setting of the detectable surface of the liquid level sensor 4 needs to be slightly higher than the liquid level corresponding to the safety threshold of the gas contained in the water pump when the water pump is working, so as to reserve a certain space to ensure that the water pump will not have excessive gas.

[0059] In the first specific embodiment, since the entire operation of the water pump is controlled by a control cabinet, and the control cabinet must include at least one PLC control unit, the controller 5 can be integrated into the PLC control unit of the control cabinet.

[0060] As a preferred embodiment, in the automatic exhaust device for water pump, the exhaust valve 1 is an automatic exhaust valve;

[0061] The automatic exhaust valve is preset with a pressure threshold. When the internal gas pressure of the water pump exceeds the preset pressure threshold, the automatic exhaust valve starts to work.

[0062] In a preferred embodiment of the present invention, the exhaust valve 1 is an automatic exhaust valve, which belongs to the prior art and can activate the automatic exhaust function when the gas accumulated in the water pump exceeds the design threshold of the automatic exhaust valve itself, and cooperate with the liquid level sensor 4 to form a double guarantee for the suction and discharge of gas in the water pump.

[0063] As a preferred embodiment, in the automatic exhaust device for water pump, the exhaust valve 1 is an electrically controlled exhaust valve;

[0064] The electrically controlled exhaust valve works according to the control signal of the controller 5 .

[0065] In another preferred embodiment of the present invention, the exhaust valve 1 is an electrically controlled exhaust valve, which will open and perform exhaust work only after receiving a control signal from the controller 5. Compared with an automatic exhaust valve, it is more conducive to automated electronic control.

[0066] As a preferred embodiment, the automatic exhaust device for water pumps further comprises a first pressure sensor and a second pressure sensor;

[0067] The first pressure sensor is arranged inside the water pump and electrically connected to the control terminal 5, and is used to detect the water inlet pressure of the water pump and output the water inlet pressure value;

[0068] The second pressure sensor is arranged inside the water pump and electrically connected to the control terminal 5, and is used to detect the outlet water pressure of the water pump and output the outlet water pressure value;

[0069] The controller 5 controls the exhaust valve to continue exhausting and controls the water pump to stop working according to the detected electrical signal, the water inlet pressure value and the water outlet pressure value, when the liquid level in the main pipe 21 does not reach the preset liquid level, the water inlet pressure value is not zero, and the water outlet pressure value is zero.

[0070] Another specific embodiment is now provided to further illustrate and explain the technical solution:

[0071] In the second specific embodiment of the present invention, different from the first specific embodiment described above, in addition to the setting of the liquid level sensor 4, two additional pressure sensors are set inside the water pump and new judgment conditions are set accordingly: the additional pressure sensors inside the water pump are used to detect the water inlet pressure and water outlet pressure of the water pump respectively. When the water inlet pressure is not zero and the water outlet pressure is zero, it means that the external water inlet has not stopped but the water outlet has stopped, and the water pump is in an abnormal working state. At this time, if the liquid level sensor 4 sends an electrical signal indicating that the liquid level in the main pipe 21 has not reached the preset liquid level at the same time, it means that too much gas has indeed accumulated in the water pump, and the controller 5 needs to issue a corresponding instruction to make the water pump start to stop the pump for self-protection and exhaust. In the above second specific embodiment, by adding a pressure sensor, the water pump is stopped only when the three judgment conditions are met at the same time, which can avoid other damages caused by the sudden start and stop of the water pump in a short time due to misjudgment to a certain extent.

[0072] As a preferred embodiment, the automatic exhaust device of the water pump is as follows: Figure 2 As shown, the first connecting pipe 23 includes a DN15 single-wire head 231 and a short tube 232, one end of the DN15 single-wire head 231 is fixedly connected to one end of the short tube 232, and the other end of the DN15 single-wire head 231 is fixedly connected to the suction hole 11 by a threaded connection.

[0073] In another preferred embodiment of the present invention, the first connecting pipe 23 includes a DN15 monofilament head 231 and a short pipe 232. Figure 1-2 As shown, the two ends of the short tube 232 are respectively welded and fixedly connected to the DN15 single-wire head 231 and the first connecting member 2 to enhance the overall structural strength and sealing of the exhaust structure; and the DN15 single-wire head 231 is connected to the automatic exhaust valve 1 by a threaded connection, which facilitates the disassembly, inspection and maintenance of the automatic exhaust valve 1 while maintaining the sealing.

[0074] As a preferred embodiment, the automatic exhaust device of the water pump is as follows: Figure 1-2 As shown, the second connecting pipe 31 includes a first oblique pipe 311 and a second oblique pipe 312;

[0075] One end of the first oblique tube 311 is fixedly connected to the second connecting member 3, and the other end of the first oblique tube 311 has a wedge-shaped cross section;

[0076] One end of the second oblique tube 312 is fixedly connected to the first connecting member 2 , and the other end of the second oblique tube 312 matches and is fixedly connected to the other end of the first oblique tube 311 .

[0077] In another preferred embodiment of the present invention, the second connecting pipe 31 is configured to extend obliquely to the side and then vertically upward in order to avoid the outward extending and expanding appearance structure of the upper part of the water pump, thereby preventing the occurrence of setting interference, wherein the inclination angles of the first oblique pipe 311 and the second connecting member 3 need to be set according to the overall shape of the water pump.

[0078] As a preferred embodiment, in the water pump automatic exhaust device, the second connecting pipe 31 is a bendable sealing hose;

[0079] The first connecting member 2 is fixed by an external bracket.

[0080] In another preferred embodiment of the present invention, in order to avoid the outward extending and expanding appearance structure of the upper part of the water pump, the second connecting pipe 31 can also be set as a bendable sealing hose. At this time, the first connecting member 2 needs an external bracket for fixation because it has no hard pipe as support.

[0081] As a preferred embodiment, the automatic exhaust device of the water pump is as follows: Figure 2 As shown, a surface thread is provided near the front end of the liquid level sensor 4;

[0082] The inner wall of the branch pipe 22 is provided with a thread matching the liquid level sensor 4 , and the liquid level sensor 4 and the branch pipe 22 are fixedly connected by threaded connection.

[0083] In another preferred embodiment of the present invention, the liquid level sensor 4 is connected to the branch pipe 22 by threaded connection, so as to facilitate the disassembly and inspection of the liquid level sensor 4.

[0084] As a preferred embodiment, in the automatic exhaust device for water pumps, the liquid level sensor 4 is a photoelectric liquid level sensor, including a photoelectric detection device arranged at the front end of the liquid level sensor 4 and an indicator light 41 arranged at the rear end of the liquid level sensor 4;

[0085] The photoelectric detection device is electrically connected to the indicator light 41 .

[0086] In another preferred embodiment of the present invention, the liquid level sensor 4 is limited to a photoelectric liquid level sensor, which can further improve the accuracy of liquid level detection. The photoelectric detection device used for detection is electrically connected to the indicator light 41 arranged at the tail of the sensor. When the liquid level cannot be detected, an electrical signal is sent to the indicator light 41 to control the indicator light 41 to light up, so that the user can more intuitively observe whether there is a problem with the operating condition of the water pump.

[0087] A control method for a water pump automatic exhaust device is applied to the water pump automatic exhaust device in the first specific embodiment, and comprises:

[0088] Step A1: The liquid level sensor continuously detects the liquid level in the main pipe to determine whether the liquid level has reached a preset level:

[0089] If yes, return to step A1;

[0090] If not, go to step A2;

[0091] Step A2, the controller controls the water pump to stop working, and controls the exhaust valve to continue exhausting work until the liquid level sensor detects that the liquid level reaches a preset liquid level;

[0092] In step A3, the controller controls the water pump to work and returns to step A1.

[0093] A control method for a water pump automatic exhaust device is applied to the water pump automatic exhaust device in the second specific embodiment, and comprises:

[0094] Step B1, the liquid level sensor continuously detects the liquid level in the main pipe to determine whether the liquid level reaches a preset liquid level; and

[0095] The first pressure sensor and the second pressure sensor respectively continuously detect the water inlet pressure and the water outlet pressure of the water pump to determine whether the water inlet pressure value and the water outlet pressure value are zero:

[0096] If the liquid level reaches the preset liquid level and the water inlet pressure value is not zero and the water outlet pressure value is zero, go to step B2;

[0097] If the liquid level does not reach the preset liquid level, and / or the water inlet pressure value is zero, and / or the water outlet pressure value is not zero, return to step B1;

[0098] Step B2, the controller controls the water pump to stop working, and controls the exhaust valve to continue exhausting work until the liquid level sensor detects that the liquid level reaches a preset liquid level;

[0099] Step B3, the controller controls the water pump to work and returns to step B1.

[0100] To sum up, through this technical solution, it is possible to further monitor the operating conditions of the water pump, while further effectively reducing the risk of damage to the device due to gas accumulation. In addition, this type of automatic exhaust device also has the advantages of high degree of automation, reliable performance, simple structure, easy assembly and easy promotion.

[0101] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. An automatic exhaust device for a water pump, applied to a water pump, the water pump comprising an exhaust port and a control cabinet, the control cabinet being used to control the operating condition of the water pump, characterized in that: The water pump automatic exhaust device is arranged at the exhaust port, and specifically comprises: an exhaust valve, comprising an air intake hole and an air exhaust hole, for exhausting the gas in the water pump; A first connecting member, comprising a main pipe and a branch pipe connected to the main pipe, one end of the main pipe being connected to the air suction hole through a first connecting pipe; a second connecting member, one end of which is connected to the exhaust port, and the other end of which is connected to the other end of the main pipe via a second connecting pipe; a liquid level sensor connected to the branch pipe, used to detect whether the liquid level in the main pipe reaches a preset liquid level, and output a corresponding detection electrical signal; A controller is arranged in the control cabinet and electrically connected to the liquid level sensor and the exhaust valve. According to the detection electrical signal, when the liquid level in the main pipe does not reach the preset liquid level, the exhaust valve is controlled to continue the exhaust operation and the water pump is controlled to stop working.

2. The automatic exhaust device for a water pump according to claim 1, characterized in that: The exhaust valve is an automatic exhaust valve; The automatic exhaust valve is preset with a pressure threshold. When the internal gas pressure of the water pump exceeds the preset pressure threshold, the automatic exhaust valve starts to work.

3. The automatic exhaust device for a water pump according to claim 1, characterized in that: The exhaust valve is an electrically controlled exhaust valve; The electrically controlled exhaust valve operates according to a control signal from the controller.

4. The automatic exhaust device for a water pump as claimed in claim 1, characterized in that: The water pump automatic exhaust device also includes a first pressure sensor and a second pressure sensor; The first pressure sensor is disposed inside the water pump and electrically connected to the controller, and is used to detect the water inlet pressure of the water pump and output the water inlet pressure value; The second pressure sensor is arranged inside the water pump and electrically connected to the controller, and is used to detect the outlet water pressure of the water pump and output the outlet water pressure value; The controller controls the exhaust valve to continue exhausting and controls the water pump to stop working according to the detection electrical signal, the water inlet pressure value and the water outlet pressure value, when the liquid level in the main pipe does not reach the preset liquid level, the water inlet pressure value is not zero, and the water outlet pressure value is zero.

5. The automatic exhaust device for a water pump as claimed in claim 1, characterized in that: The first connecting pipe includes a DN15 single-wire head and a short tube, one end of the DN15 single-wire head is fixedly connected to one end of the short tube, and the other end of the DN15 single-wire head is fixedly connected to the suction hole by means of a threaded connection.

6. The automatic exhaust device for a water pump as claimed in claim 1, characterized in that: The second connecting pipe includes a first oblique pipe and a second oblique pipe; One end of the first oblique tube is fixedly connected to the second connecting piece, and the other end of the first oblique tube has a wedge-shaped cross section; One end of the second oblique tube is fixedly connected to the first connecting member, and the other end of the second oblique tube matches and is fixedly connected to the other end of the first oblique tube.

7. The automatic exhaust device for a water pump as claimed in claim 1, characterized in that: The second connecting pipe is a bendable sealing hose; The first connecting member is fixed by an external bracket.

8. The automatic exhaust device for a water pump as claimed in claim 1, characterized in that: The liquid level sensor is a photoelectric liquid level sensor, comprising a photoelectric detection device arranged at the front end of the liquid level sensor and an indicator light arranged at the rear end of the liquid level sensor; The photoelectric detection device is electrically connected to the indicator light.

9. A control method for a water pump automatic exhaust device, characterized in that: The automatic exhaust device for a water pump as claimed in claim 1 comprises: Step A1: The liquid level sensor continuously detects the liquid level in the main pipe to determine whether the liquid level reaches a preset liquid level. If yes, return to step A1; If not, go to step A2; Step A2, the controller controls the water pump to stop working, and controls the exhaust valve to continue exhausting work, until the liquid level sensor detects that the liquid level reaches the preset liquid level; In step A3, the controller controls the water pump to work and returns to step A1.

10. A control method for a water pump automatic exhaust device, characterized in that: Applicable to the automatic exhaust device for a water pump as claimed in claim 4, and comprising: Step B1, the liquid level sensor continuously detects the liquid level in the main pipe to determine whether the liquid level reaches a preset liquid level; and The first pressure sensor and the second pressure sensor respectively continuously detect the water inlet pressure and the water outlet pressure of the water pump to determine whether the water inlet pressure value and the water outlet pressure value are zero: If the liquid level reaches the preset liquid level and the water inlet pressure value is not zero and the water outlet pressure value is zero, go to step B2; If the liquid level does not reach the preset liquid level, and / or the water inlet pressure value is zero, and / or the water outlet pressure value is not zero, return to step B1; Step B2, the controller controls the water pump to stop working, and controls the exhaust valve to continue exhausting work, until the liquid level sensor detects that the liquid level reaches the preset liquid level; In step B3, the controller controls the water pump to work and returns to step B1.

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