Claw pump

Abstract

A claw pump (10) for generating a vacuum, the claw pump comprising: a housing having an inlet and an outlet; at least one pump stage (12) constructed as a claw pump stage in the housing, driven by the electric motor to convey the gaseous medium from the inlet to the outlet; a temperature sensor (18) connected to the outlet to detect the temperature of the claw pump (10); and a controller (20) connected to the temperature sensor (18), where the controller (20) is configured to generate a first control signal if the temperature of the claw pump (10) exceeds a first temperature threshold.

Description

[0001] The present invention relates to a claw pump for generating a vacuum and a method for operating such a claw pump.

[0002] A typical claw pump consists of a housing with an inlet and an outlet. The housing defines a pump chamber in which the claw pump stage is arranged. The claw pump stage typically comprises two rotors (each with a pump element) acting as claws, which interact with each other when rotated by an electric motor. Thus, through the interaction of the claws, the gaseous medium is conveyed from the inlet to the outlet of the claw pump. The operation of the claw pump is primarily non-contact, meaning there is little or no contact between the individual claws of the pump stage and between the claws and the housing, reducing the risk of jamming and preventing damage to the pump. If the temperature of the claw pump exceeds a certain threshold, due to thermal expansion, the rotating parts of the claw pump may come into contact with the housing or with each other, increasing the risk of jamming or damage to the vacuum pump. This occurs particularly when the claw pump approaches its ultimate pressure / maximum vacuum, as less gaseous medium is pumped and less heat is dissipated by the pumped gaseous medium itself.

[0003] To prevent damage to claw pumps, it is well known to implement a vacuum relief valve, which is typically constructed as a biased reflux valve. If the vacuum at the inlet is higher than a certain threshold (i.e., the pressure is lower than a threshold), this biased reflux valve opens against the bias, allowing ambient air to be introduced into the claw pump inlet. This additional ambient air cools the claw pump stage by dissipating heat and prevents damage or seizure of the pump stage. However, implementing a vacuum relief valve limits the maximum pressure achievable by the claw pump. Simultaneously, the additional gas flow through the vacuum relief valve results in a reduced flow rate, leading to a decrease in pump efficiency.

[0004] The purpose of this invention is to provide a claw pump and an operating method to provide improved efficiency while preventing the claw pump from jamming or being damaged.

[0005] This objective is achieved by the claw pump according to claim 1 and the method for operating the claw pump according to claim 8.

[0006] The claw pump for generating a vacuum according to the invention includes a housing having an inlet and an outlet. Further, at least one pump stage is disposed within the housing, wherein the at least one pump stage is constructed as a claw pump stage and driven by an electric motor to deliver a gaseous medium from the inlet to the outlet. Of course, the claw pump may include additional pump stages, which may also be constructed as claw pump stages, or may include different pumping mechanisms, such as screw pump stages, rotary vane pump stages, etc. Further, according to the invention, a temperature sensor is connected to the housing to detect the temperature of the claw pump. The temperature sensor is connected to the outlet. Typically, the highest temperature of the claw pump is detected at the outlet, thus providing a good indication of the temperature of the claw pump stage itself.

[0007] According to the present invention, the claw pump includes a controller connected to a temperature sensor and receiving a temperature detected by the temperature sensor. The controller is configured to generate a first control signal if the temperature of the claw pump exceeds a first temperature threshold.

[0008] Specifically, the claw pump does not include a vacuum release valve. Therefore, there is no vacuum release valve to limit the ultimate pressure of the claw pump. Furthermore, there is no additional or extra gas flow through the vacuum release valve, which would otherwise reduce the efficiency of the claw pump, especially near its ultimate pressure. However, at the same time, since the temperature of the claw pump is directly measured by a temperature sensor, an indication of the claw pump's temperature is provided, thus preventing an increase in damage or jamming of the claw pump.

[0009] Preferably, a warning signal is generated via the first control signal, thereby providing indication information to the user or operator of the claw pump. Therefore, the first control signal can trigger a warning signal, which can be an optical signal, an acoustic signal, or any other type of warning signal indicating an increase in the temperature of the claw pump. The warning signal can be generated by the controller itself or transmitted to another device via any type of data connection to provide indication information to the user.

[0010] Preferably, the controller is configured to reduce the motor speed of the electric motor in response to a first control signal. Therefore, when a temperature above a first temperature threshold is detected, the motor speed of the electric motor is reduced to decrease heat generation in the claw pump stage and to prevent further temperature increases. In this configuration, the controller uses the first control signal to control the electric motor of the claw pump. Specifically, the controller is configured to reduce the motor speed of the electric motor as the temperature increases. In particular, a continuous reduction in the motor speed of the electric motor can be applied as the temperature increases. Therefore, the controller can provide a correlation between temperature and motor speed. This correlation can be linear, or it can be any other kind of relationship between the motor speed and temperature.

[0011] Preferably, the controller is configured to generate a second control signal to shut down the claw pump if the motor speed of the claw pump is equal to or below a motor speed threshold. Specifically, the claw pump requires a minimum motor speed, particularly to maintain lubrication of the gears and other moving parts within the pump. Therefore, if the motor speed of the claw pump drops below the motor speed threshold, damage to these moving parts may occur. To prevent damage, the claw pump is shut down.

[0012] Preferably, the controller is configured to generate a second control signal to shut down the claw pump if the temperature of the claw pump exceeds a second temperature threshold. The second temperature threshold is greater than the first temperature threshold. Therefore, if the temperature of the claw pump exceeds the second temperature threshold, there is a risk of serious damage. Therefore, shutting down the claw pump prevents any damage. Specifically, in conjunction with a reduction in motor speed, if, as described above, the temperature continues to increase despite a reduction in motor speed, the claw pump is shut down when the second temperature threshold is exceeded to prevent damage to the claw pump.

[0013] Preferably, a warning signal is generated via the second control signal, thereby providing indication information to the user or operator of the claw pump. Therefore, the second control signal can trigger the warning signal, which can be an optical signal, an acoustic signal, or any other type of warning signal indicating an increase in the temperature of the claw pump. Specifically, the warning signal indicates to the user that the shutdown of the claw pump is caused by an increase in temperature reaching or exceeding a second temperature threshold. The warning signal can be generated by the controller itself or can be transmitted to another device via any type of data connection to provide indication information to the user.

[0014] In another aspect of the invention, a method for operating a claw pump is provided. The claw pump includes a housing having an inlet and an outlet. Further, the claw pump includes at least one pump stage configured as a claw pump stage disposed within the housing and driven by an electric motor to deliver a gaseous medium from the inlet to the outlet. The method includes: Monitor the temperature of the claw pump during operation, and If the temperature exceeds the first temperature threshold, a first control signal is generated.

[0015] Therefore, the temperature of the claw pump is directly measured and used to generate a first control signal. This first control signal can trigger a warning signal indicating an increase in temperature. This prevents the claw pump from jamming or being damaged due to the increased temperature exceeding a first temperature threshold.

[0016] In particular, the claw pump of this method can be further constructed according to the characteristics of the claw pump described above.

[0017] Preferably, in response to the first control signal, the motor speed of the electric motor is reduced. Therefore, if the temperature of the claw pump exceeds a first temperature threshold, the heat generation of the claw pump is reduced by decreasing the motor speed of the electric motor. Preferably, the motor speed decreases as the temperature increases.

[0018] Preferably, the claw pump is shut down if the motor speed is equal to or below the motor speed threshold.

[0019] Preferably, the claw pump is shut down if the temperature exceeds a second temperature threshold. The second temperature threshold is greater than the first temperature threshold.

[0020] The invention is described in more detail below with reference to the accompanying drawings.

[0021] The attached diagram shows: Figure 1 A claw pump schematically illustrated according to the present invention, Figure 2 The diagram shows the operation of the claw pump according to the invention, and Figure 3 A flowchart of the method according to the present invention.

[0022] refer to Figure 1 The diagram illustrates a claw pump 10 according to the invention. The claw pump 10 includes at least one pump stage 12, which is configured as a claw pump stage having an inlet 14 and an outlet 16. The claw pump stage 12 is driven by an electric motor connected to a controller 20. The controller may integrate a motor controller, or an external motor controller may be located between the electric motor of the claw pump 10 and the controller 20, such that control signals from the controller 20 can be further processed by the motor controller and transmitted to the electric motor. Further, the claw pump 10 includes a temperature sensor 18 connected to the outlet 16. Other locations are also possible. The temperature of the claw pump stage 12 is detected by the temperature sensor 18. The controller 20 receives the temperature detected by the temperature sensor 18 and is configured to generate a first control signal if the temperature detected by the temperature sensor 18 exceeds a first temperature threshold. The first control signal can generate a warning signal indicating an increase in temperature in the claw pump 10, which can be used to prevent jamming and / or damage to the claw pump 10.

[0023] Specifically, in response to the first control signal generated by controller 20, the motor speed of claw pump stage 12 decreases. This is in Figure 2An example is provided, illustrating the motor speed "rpm" of the claw pump stage 12. Below a first temperature threshold T1, the claw pump stage 12 is allowed to operate at full motor speed (indicated as RPM1). As the temperature increases and exceeds the first temperature threshold T1, a reduction in motor speed is applied by the controller 20. This means that the motor speed "rpm" decreases with the temperature of the claw pump 10. Figure 2 In the example, the relationship between temperature T and motor speed "rpm" is shown as linear. However, other relationships between temperature T and "rpm" are also possible. If temperature T increases further and reaches a second temperature threshold T2, the claw pump 10 is shut off to prevent damage and the motor speed is reduced to 0. Specifically, the second temperature threshold T2 may correspond to a minimum motor speed RPM2. In particular, the claw pump 10 requires a minimum motor speed to maintain lubrication of moving parts (such as the gears of the claw pump). If temperature T exceeds the second temperature threshold T2, the motor speed of the electric motor will need to be controlled below the minimum motor speed RPM2 of the claw pump 10, which may lead to damage to the moving parts. Therefore, the claw pump 10 is shut off.

[0024] It is mentioned below Figure 3 The figure shows a schematic flowchart of the method according to the present invention. Figure 3 The methods shown include: In step S01, the temperature of the claw pump is detected during operation.

[0025] In step S02, if the temperature exceeds the first temperature threshold, a first control signal is generated.

[0026] Specifically, the method is further constructed according to the characteristics of the claw pump described above. Specifically, a first control signal is used to reduce the motor speed of the electric motor, and a second control signal is generated to shut down the claw pump if the temperature exceeds a second temperature threshold.

[0027] Therefore, this invention provides a claw pump and a method for operating the claw pump, wherein improved ultimate pressure can be achieved more efficiently than in the prior art and the need for any vacuum relief valve is eliminated. Simultaneously, damage to the claw pump due to overheating can be prevented by detecting the temperature of the claw pump.

[0028] List of reference numerals 10 Claw Pumps 12 Claw Pump Stage 14 Entrances 16 Exports 18 Temperature Sensor 20 Controllers

Claims

1. A claw pump for generating a vacuum, comprising: A shell having an inlet and an outlet; At least one pump stage, constructed as a claw pump stage within the housing, is driven by an electric motor to deliver a gaseous medium from the inlet to the outlet; A temperature sensor is connected to the outlet to detect the temperature of the claw pump; as well as A controller connected to the temperature sensor, wherein the controller is configured to generate a first control signal if the temperature of the claw pump exceeds a first temperature threshold.

2. The claw pump according to claim 1, wherein, The first control signal triggers a warning signal, which provides instruction information to the user.

3. The claw pump according to claim 1 or 2, wherein, The controller is configured to reduce the motor speed of the electric motor in response to the first control signal.

4. The claw pump according to any one of claims 3, wherein, The controller is configured to reduce the motor speed of the electric motor as the temperature increases.

5. The claw pump according to claim 3 or 4, wherein, The controller is configured to generate a second control signal to shut down the claw pump if the motor speed of the claw pump is equal to or below a motor speed threshold.

6. The claw pump according to any one of claims 1 to 5, wherein, The controller is configured to generate a second control signal to shut down the claw pump if the temperature of the claw pump exceeds a second temperature threshold.

7. The claw pump according to any one of claims 1 to 6, wherein, The claw pump does not include a vacuum release valve.

8. A method for operating a claw pump, the claw pump comprising: A shell having an inlet and an outlet; And at least one pump stage constructed as a claw pump stage within the housing, driven by an electric motor to deliver a gaseous medium from the inlet to the outlet; the method includes: The temperature of the claw pump is monitored during operation; as well as If the temperature exceeds a first temperature threshold, a first control signal is generated.

9. The method according to claim 8, wherein, In response to the first control signal, the motor speed of the electric motor is reduced.

10. The method according to claim 9, wherein, The motor speed decreases as the temperature increases.

11. The method according to claim 8 or 10, wherein, If the motor speed is equal to or below a motor speed threshold, a second control signal is generated to shut down the claw pump.

12. The method according to any one of claims 8 to 11, wherein, If the temperature exceeds the second temperature threshold, a second control signal is generated to shut down the claw pump.

13. The method according to any one of claims 8 to 12, wherein, The claw pump is constructed as described in any one of claims 1 to 7.

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