Control method and system for protecting vacuum pump

Abstract

The present invention proposes a control method and system for protecting a vacuum pump, the method comprising: using a temperature sensor to sense the temperature of a pump casing in real time; step 1, according to the temperature of the pump casing, the PLC mainboard of the vacuum pump determines whether it is necessary to turn on the fan of the unit and change the speed; step 2, according to the temperature of the pump casing, the PLC mainboard of the vacuum pump determines whether the motor needs to run to the first speed. The present invention solves the problem of heat dissipation of the unit and the problem of temperature difference between the inside and outside of the unit.

Description

Technical Field

[0001] The invention belongs to the field of vacuum pumps, and in particular relates to a control method and system for protecting a vacuum pump. Background Art

[0002] The vacuum pump comprises a pumping element which is arranged in a pumping chamber formed by the pump housing and which serves to convey a fluid, in particular a gas such as air. The pumping element is usually driven by an electric motor. In order to simply change the rotation speed of the vacuum pump, it is known to use a frequency converter in order to be able to change the motor speed in a simple manner. The frequency converter is a sensitive electronic component.

[0003] The dry vacuum pump uses water to help dissipate heat for the entire unit, but when the unit is running at rated current and the frequency is higher than 60Hz, the temperature may be higher. At this time, when the process cooling water cannot completely take away the heat emitted by the unit, the unit will also add a cooling fan.

[0004] Defects in the prior art:

[0005] 1. After the cooling fan is turned on, the temperature trend of the unit cannot be controlled. When the purge is continuous, the temperature of the outer shell is too low, which will increase the temperature difference between the inside and outside, causing different mechanical expansion amounts and leading to wear.

[0006] 2. If the heat dissipation of the fan is reduced, the unit will have different risks when used by the client due to factors such as water temperature, working current, and environment. Summary of the invention

[0007] The purpose of the present invention is to provide a control method and system for protecting a vacuum pump, which solves the problem of heat dissipation of the unit and the problem of temperature difference between the inside and outside of the unit.

[0008] A control method for protecting a vacuum pump is based on a vacuum pump, the vacuum pump comprising: a pump body, an oil tank and a cooling water tower, the pump body comprising a housing and provided with a water inlet and a water outlet, the cooling water tower being connected to the water inlet and the water outlet via pipelines, the pump body comprising a pump housing forming a pumping cavity, a temperature sensor being arranged on the pump housing, at least one pumping element, a motor for driving the at least one pumping element, and a frequency converter connected to the motor for changing the rotation speed of the motor being arranged in the pumping cavity, the control method comprising the following steps:

[0009] The temperature of the pump casing is sensed in real time by a temperature sensor;

[0010] Step 1: According to the temperature of the pump casing, the PLC mainboard of the vacuum pump determines whether the fan of the unit needs to be turned on and the speed needs to be changed, which specifically includes the following steps:

[0011] When the pump housing temperature is ≤X℃, the PLC mainboard of the vacuum pump sends a control signal to the unit fan, and the unit fan is turned off;

[0012] When the pump casing temperature is ≥Y℃, the PLC mainboard of the vacuum pump sends a control signal to the unit fan, and the unit fan turns on;

[0013] When the pump housing temperature is less than A℃, the PLC mainboard of the vacuum pump sends the first control signal to the inverter, the inverter does not act, and the motor keeps running at the first speed;

[0014] When the pump housing temperature is ≥A℃, the PLC mainboard of the vacuum pump sends a second control signal to the inverter, the inverter operates, and the motor runs at the second speed; at this time, the motor runs to B Hz;

[0015] Among them, X<Y<A; the second speed<the first speed;

[0016] Step 2: Based on the pump housing temperature, the PLC mainboard of the vacuum pump determines whether the motor needs to run to the first speed, including the following steps:

[0017] When the pump casing temperature is ≤A-10℃, the PLC mainboard of the vacuum pump sends a third control signal to the inverter, the inverter operates, and the motor returns to the first speed.

[0018] Preferably, the first control signal is used to indicate that the running speed of the motor is within a safety threshold under the current pump housing temperature.

[0019] Preferably, the second control signal is used to indicate that the amount of heat removed by the fan of the unit is insufficient.

[0020] Preferably, the third control signal is used to indicate that the heat dissipated by the fan of the unit is sufficient, and the operating speed of the motor can be restored to the first speed at the temperature of the pump casing after the heat dissipation.

[0021] Preferably, A=120°C, B=30 Hz, X=60°C, and Y=110°C.

[0022] A monitoring system for protecting a vacuum pump, comprising: a pump body, an oil tank and a cooling water tower, wherein the pump body comprises a housing and is provided with a water inlet and a water outlet, the cooling water tower is respectively connected to the water inlet and the water outlet via pipelines, the pump body comprises a pump housing forming a pumping chamber, at least one pumping element, a motor for driving the at least one pumping element, and a frequency converter connected to the motor for changing the rotation speed of the motor are arranged in the pumping chamber, and the monitoring system comprises:

[0023] a temperature sensor disposed on the pump housing, for sensing the pump housing temperature of the pump housing in real time;

[0024] A monitoring unit is configured to obtain the pump housing temperature, the water inlet temperature and the water outlet temperature, calculate the temperature difference, and perform steps 1 and 2;

[0025] The unit fan unit comprises at least one unit fan.

[0026] Preferably, the unit fan is installed on the pump housing.

[0027] Preferably, it also includes a water inlet temperature sensor arranged at the water inlet, which is used to sense the water inlet temperature of the vacuum pump in real time;

[0028] The outlet water temperature sensor is arranged at the outlet water, and is used to sense the outlet water temperature of the vacuum pump in real time.

[0029] Preferably, the vacuum pump is a dry vacuum pump, and the temperature sensor is a PT1000 temperature sensor.

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] 1. Increase industrial adaptability: Facing different terminals, the unit can operate stably without being affected by the water quality at the plant end.

[0032] 2. Increase process adaptability: It can operate stably with different processes and different heat generation.

[0033] 3. Reduce energy consumption: When the water flow of the unit is stable or the unit operating requirements are low, turning off the fan can reduce the energy consumption of the unit.

[0034] 4. Increase operational reliability: This method can control the internal and external temperatures of the unit within a certain range, reduce the impact of client water flow, and dissipate the heat of the unit.

[0035] 5. Meet the needs of lean production: fans with uniform air volume requirements can be installed to reduce the error rate of production line installation and reduce the amount of inventory.

[0036] 6. The water temperature monitoring method of properly arranging two-way temperature sensing devices replaces the water flow meter that is indispensable in the existing solution, which reduces the hardware cost and provides a more cost-effective solution. At the same time, its long-term use is not affected by water quality and will not cause adverse conditions such as damage to the sensing element, so it has the advantage of higher long-term reliability. In the prior art, the operation of vacuum pumps, especially dry screw vacuum pumps, depends on water for cooling, so the size of the water flow rate is related to the stable operation of the vacuum pump. For the above reasons, vacuum pumps generally use water flow meters to directly monitor the size of the water flow and output alarm signals. However, the monitoring of water flow meters still has certain defects, such as high cost, stability depends on the water quality of the client, insufficient performance stability of the water flow meter itself or inaccurate monitoring results, high maintenance costs, and low cost performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Flow chart for reducing the unit frequency to control the temperature;

[0038] Figure 2 Flow chart for unit fan temperature control

[0039] Figure 3 Diagram of the control system for protecting the vacuum pump. DETAILED DESCRIPTION

[0040] The control method and system of the protective vacuum pump of the present invention will be described in more detail below in conjunction with the schematic diagram, wherein the preferred embodiment of the present invention is shown, and it should be understood that the present invention described herein can be modified by a person skilled in the art, while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as being widely known to a person skilled in the art, and not as a limitation of the present invention.

[0041] like Figures 1-2 As shown, a control method for protecting a vacuum pump is provided, based on a vacuum pump, the vacuum pump comprises: a pump body, an oil tank and a cooling water tower, the pump body comprises a shell and is provided with a water inlet and a water outlet, the cooling water tower is respectively connected to the water inlet and the water outlet via a pipeline, the pump body comprises a pump shell forming a pumping chamber, a temperature sensor is arranged on the pump shell, a water inlet temperature sensor is arranged at the water inlet, and a water outlet temperature sensor is arranged at the water outlet, at least one pumping element, a motor for driving at least one pumping element, and a frequency converter connected to the motor for changing the rotation speed of the motor are arranged in the pumping chamber, and the control method comprises the following steps:

[0042] The temperature of the pump housing is sensed in real time by the temperature sensor PT1000;

[0043] Step 1: According to the temperature of the pump casing, the PLC mainboard of the vacuum pump determines whether the fan of the unit needs to be turned on and the speed needs to be changed, which specifically includes the following steps:

[0044] When the pump housing temperature is ≤X℃, the PLC mainboard of the vacuum pump sends a control signal to the unit fan, and the unit fan is turned off;

[0045] When the pump casing temperature is ≥Y℃, the PLC mainboard of the vacuum pump sends a control signal to the unit fan, and the unit fan turns on;

[0046] When the pump housing temperature is less than A℃, the PLC mainboard of the vacuum pump sends the first control signal to the inverter, the inverter does not act, and the motor keeps running at the first speed;

[0047] When the pump casing temperature is ≥A℃, the PLC mainboard of the vacuum pump sends a second control signal to the inverter, the inverter operates, and the motor runs at the second speed; at this time, the motor runs to B Hz.

[0048] Among them, X<Y<A; the second speed is <the first speed.

[0049] In this embodiment, A=120°C, B=30 Hz, X=60°C, and Y=110°C.

[0050] The first control signal is used to indicate that the running speed of the motor is within a safety threshold under the current pump housing temperature.

[0051] The second control signal is used to indicate that the heat dissipated by the fan of the unit is insufficient.

[0052] Step 2: Based on the pump housing temperature, the PLC mainboard of the vacuum pump determines whether the motor needs to run to the first speed, including the following steps:

[0053] When the pump casing temperature is ≤A-10℃, the PLC mainboard of the vacuum pump sends a third control signal to the inverter, the inverter operates, and the motor returns to the first speed.

[0054] The third control signal is used to indicate that the heat dissipated by the fan of the unit is sufficient, and the operating speed of the motor can be increased at the temperature of the pump casing after the heat is dissipated.

[0055] In addition, the control method for protecting the vacuum pump also includes the following steps:

[0056] Using a water inlet temperature sensor and a water outlet temperature sensor to respectively sense the water inlet temperature and the water outlet temperature of the vacuum pump in real time;

[0057] Calculate a first temperature difference between the water inlet temperature and the water outlet temperature;

[0058] Determine whether the first temperature difference value is continuously greater than the upper limit value of the inlet and outlet water temperature difference to reach a first time threshold, and if so, output a first alarm signal; the first alarm signal is used to indicate that the water flow of the vacuum pump is insufficient during operation.

[0059] Determine whether the first temperature difference value is continuously less than the lower limit value of the inlet and outlet water temperature difference and reaches a second time threshold. If so, output a second alarm signal; the second alarm signal is used to indicate insufficient water flow when the vacuum pump is turned on.

[0060] The upper limit of the inlet and outlet water temperature difference, the first time threshold, the lower limit of the inlet and outlet water temperature difference, the second time threshold, and the temperature change threshold depend on the motor power, operating frequency, and heat generation of the vacuum pump at the operating vacuum degree of the vacuum pump.

[0061] The upper limit of the inlet and outlet water temperature difference is in the range of 15°C-25°C, the lower limit of the inlet and outlet water temperature difference is in the range of 3°C-10°C, the temperature change threshold is in the range of 3°C-10°C, and the first time threshold and the second time threshold are in the range of 30-120 seconds.

[0062] like Figure 3 As shown, a monitoring system for protecting a vacuum pump comprises:

[0063] A vacuum pump, comprising: a pump body, an oil tank and a cooling water tower, wherein the pump body comprises a housing and is provided with a water inlet and a water outlet, the cooling water tower is respectively connected to the water inlet and the water outlet via pipelines, the pump body comprises a pump housing forming a pumping chamber, at least one pumping element is arranged in the pumping chamber, a motor for driving the at least one pumping element, and a frequency converter connected to the motor for changing the rotation speed of the motor;

[0064] a temperature sensor disposed on the pump housing, for sensing the pump housing temperature of the pump housing in real time;

[0065] A water inlet temperature sensor arranged at the water inlet, which is used to sense the water inlet temperature of the vacuum pump in real time;

[0066] A water outlet temperature sensor arranged at the water outlet, which is used to sense the water outlet temperature of the vacuum pump in real time;

[0067] The monitoring unit is a PLC mainboard of the vacuum pump, which is configured to obtain the pump housing temperature, the water inlet temperature, the water outlet temperature, calculate the temperature difference, and execute steps 1 and 2;

[0068] The unit fan unit comprises at least one unit fan which is mounted on the pump housing.

[0069] Furthermore, the frequency converter is arranged in a frequency converter housing which is closely connected to the pump housing, and the frequency converter housing and the pump housing are formed integrally.

[0070] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A control method for protecting a vacuum pump, based on a vacuum pump, the vacuum pump comprises: a pump body, an oil tank and a cooling water tower, the pump body comprises a shell and is provided with a water inlet and a water outlet, the cooling water tower is respectively connected to the water inlet and the water outlet via a pipeline, the pump body comprises a pump shell forming a pumping cavity, a temperature sensor is arranged on the pump shell, at least one pumping element, a motor for driving at least one pumping element, and a frequency converter connected to the motor for changing the rotation speed of the motor are arranged in the pumping cavity, characterized in that, The control method controls the pumping element to achieve cooperative heat dissipation when the heat dissipation taken away by the fan of the unit is insufficient, and includes the following steps: The temperature of the pump casing is sensed in real time by a temperature sensor; Step 1: According to the temperature of the pump casing, the PLC mainboard of the vacuum pump determines whether the fan of the unit needs to be turned on and the speed needs to be changed, which specifically includes the following steps: When the pump housing temperature is ≤X℃, the PLC mainboard of the vacuum pump sends a control signal to the unit fan, and the unit fan is turned off; When the pump casing temperature is ≥Y℃, the PLC mainboard of the vacuum pump sends a control signal to the unit fan, and the unit fan turns on; When the pump casing temperature is less than A℃, the PLC mainboard of the vacuum pump sends a first control signal to the frequency converter, the frequency converter does not act, and the motor keeps running at the first speed; the first control signal is used to indicate that the running speed of the motor is within the safety threshold under the current pump casing temperature; When the pump housing temperature is ≥A℃, the PLC mainboard of the vacuum pump sends a second control signal to the inverter, the inverter operates, and the motor runs at the second speed; at this time, the motor runs to B Hz; Among them, X<Y<A; the second speed is <the first speed; Step 2: Based on the pump housing temperature, the PLC mainboard of the vacuum pump determines whether the motor needs to run to the first speed, including the following steps: When the pump casing temperature is ≤A-10℃, the PLC mainboard of the vacuum pump sends a third control signal to the inverter, the inverter operates, and the motor returns to the first speed.

2. The control method for protecting a vacuum pump according to claim 1, characterized in that: The second control signal is used to indicate that the heat dissipated by the fan of the unit is insufficient.

3. The control method for protecting a vacuum pump according to claim 1, characterized in that: The third control signal is used to indicate that the heat dissipated by the fan of the unit is sufficient, and the operating speed of the motor can be restored to the first speed at the temperature of the pump casing after the heat is dissipated.

4. The control method for protecting a vacuum pump according to claim 1, characterized in that: A=120℃, B=30Hz, X=60℃, Y=110℃.

5. A monitoring system for a protective vacuum pump, used to implement the control method for a protective vacuum pump according to any one of claims 1 to 4, comprising: a pump body, an oil tank and a cooling water tower, the pump body comprising a shell and provided with a water inlet and a water outlet, the cooling water tower being connected to the water inlet and the water outlet via pipelines, the pump body comprising a pump shell forming a pumping chamber, at least one pumping element being arranged in the pumping chamber, a motor for driving at least one pumping element, and a frequency converter connected to the motor for changing the rotation speed of the motor, characterized in that: The monitoring system comprises: a temperature sensor disposed on the pump housing, for sensing the pump housing temperature of the pump housing in real time; A monitoring unit is configured to obtain the temperature of the pump casing, calculate the temperature difference, and execute step 1 and step 2; The unit fan unit comprises at least one unit fan.

6. The monitoring system for protecting a vacuum pump according to claim 5, characterized in that: The fan of the unit is installed on the pump housing.

7. The monitoring system for protecting a vacuum pump according to claim 5, characterized in that: Also includes: A water inlet temperature sensor arranged at the water inlet, which is used to sense the water inlet temperature of the vacuum pump in real time; The outlet water temperature sensor is arranged at the outlet water, and is used to sense the outlet water temperature of the vacuum pump in real time.

8. The monitoring system for protecting a vacuum pump according to claim 5, characterized in that: The vacuum pump is a dry vacuum pump, and the temperature sensor is a PT1000 temperature sensor.

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