Method for controlling an air-cooled compressor or vacuum pump device and an air-cooled compressor or vacuum pump device

1 . A method for controlling an air-cooled compressor or vacuum pump device ( 1 ) for compressing a gas, which is provided with a motor ( 5 ) having a fixed speed, wherein the compressor or vacuum pump device ( 1 ) is provided with an air-cooled cooler ( 14 ) having a fan ( 15 ) for cooling a cooling medium that is injected into a compressor or vacuum pump element of the compressor or vacuum pump device, respectively, characterized in that the method comprises the step of switching off the fan ( 15 ) when the compressor or vacuum pump device ( 1 ) is running unloaded, and that the fan ( 15 ) is provided with a timer ( 27 ) that measures the time after the fan ( 15 ) has been switched on and in that the fan ( 15 ) is switched off or reduced in speed according to the method only if the time measured by the timer ( 27 ) is also greater than a preset value.

2 . The method according to claim 1 , characterized in that the method comprises the additional step of switching off the fan ( 15 ) when the compressor or vacuum pump device ( 1 ) is running unloaded if the temperature at an outlet ( 4 ) of the compressor or vacuum pump element ( 2 ) is below a certain threshold temperature, wherein the threshold temperature is higher than the dew point of compressed gas.

3 . The method according to claim 1 , characterized in that, when the compressor or vacuum pump device ( 1 ) is running unloaded, the method comprises the additional step of controlling the fan ( 15 ) according to the following rule:

when the temperature at an outlet ( 4 ) of the compressor or vacuum pump element ( 2 ) exceeds a first temperature (T 1 ): switch on the fan ( 15 ).

4 . The method according to claim 3 , characterized in that the fan ( 15 ) has a fixed speed and in that the method comprises the following step:

when the temperature at the outlet ( 4 ) of the compressor or vacuum pump element ( 2 ) falls below a second temperature (T 2 ): switch off the fan ( 15 ).

5 . The method according to claim 4 , characterized in that the aforementioned first temperature (T 1 ) is equal to the second temperature (T 2 ) multiplied by a specific value.

6 . The method according to claim 5 , characterized in that the aforementioned specific value is between 5 and 20° C.

7 . The method according to claim 6 , characterized in that the aforementioned specific value is between 10 and 15° C.

8 . The method according to claim 4 , characterized in that the aforementioned second temperature (T 2 ) is at least equal to a dew point of the gas at the outlet of the compressor or vacuum pump device ( 1 ), wherein said dew point is measured or calculated based on a measurement of environmental parameters.

9 . The method according to claim 8 , characterized in that the dew point is measured or calculated at regular intervals or on a continuous basis.

10 . The method according to claim 3 , characterized in that the fan ( 15 ) has N different fixed speeds, and in that the method comprises the following steps:

when the fan ( 15 ) is switched on because the temperature at the outlet ( 4 ) of the compressor or vacuum pump element ( 2 ) exceeds a: the certain-first temperature (T 1 ): run the fan ( 15 ) at maximum speed;

if the temperature at the outlet ( 4 ) drops after the fan ( 15 ) is switched on, the speed of the fan ( 15 ) is gradually reduced when the temperature falls below the first temperature (T 1 ) reduced by a constant, wherein the constant becomes progressively larger for each further reduction in the speed of the fan ( 15 );

when the temperature at the outlet ( 4 ) does not decrease after the fan ( 15 ) is switched on or after the speed of the fan ( 15 ) is reduced, gradually increase the speed of the fan ( 15 ) until the temperature at the outlet ( 4 ) no longer increases or remains the same or until the maximum speed of the fan ( 15 ) is reached;

when the temperature at the outlet ( 4 ) of the compressor or vacuum pump element ( 2 ) falls below a certain second temperature (T 2 ): switch off the fan ( 15 ).

11 . The method according to claim 3 , characterized in that the fan ( 15 ) has a variable speed and in that the method comprises the following steps:

regulating the speed of the fan ( 15 ) so that the temperature at the outlet ( 4 ) is between the first temperature (T 1 ) and a second temperature (T 2 ).

12 . An air-cooled compressor or vacuum pump device provided with a motor ( 5 ) having a fixed speed, wherein the compressor or vacuum pump device ( 1 ) is provided with an air-cooled cooler ( 14 ) having a fan ( 15 ) for cooling a cooling medium that is injected into a compressor or vacuum pump element of the compressor or vacuum pump device, respectively, characterized in that the fan ( 15 ) is provided with a controller ( 19 ) that is provided with a control algorithm for carrying out a method according to claim 1 .

13 . The air-cooled compressor or vacuum pump device according to claim 12 , characterized in that the compressor or vacuum pump device ( 1 ) is provided with an after-cooler ( 18 ), wherein the after-cooler ( 18 ) is part of or integrated with the aforementioned air-cooled cooler ( 14 ).