A method for controlling the rotational speed (S) of an electric motor driven air compressor (2) that supplies compressed air to a pneumatically operated system (5) of a vehicle (1), characterized by the preliminary steps of: a) determining the efficiency (e) of the air compressor (2) for different values (Si) of the rotational speed (S) of the air compressor (2), the efficiency (e) of the air compressor (2) corresponding to the ratio between the pneumatic power (PI) produced by the air compressor (2) and the power (PO) given to the air compressor (2); b) determining one or several specific values (S2, S4) among said different values (Si), for which the efficiency (e) of the air compressor (2) is higher than a threshold value (emin) and/or comparatively higher than those determined for values (SI, S3) close to said specific value(s) (S2, S4); the preliminary steps a) and b) being preferably implemented only once; and characterized by the further repetitive steps of: c) determining the air consumption rate of the pneumatically operated system (5) receiving compressed air from the air compressor (2); d) determining a minimum rotational speed (Smin) of the air compressor (2) to obtain an air production rate of the air compressor (2) that is equal or substantially equal to said determined air consumption rate; e) determining if the specific value or one of the specific values (S2, S4) is greater than said determined minimum rotational speed (Smin); f) if no specific value is greater than said determined minimum rotational speed (Smin), controlling the rotational speed (S) of the air compressor (2) based on said minimum rotational speed (Smin); g) if only one specific value (S4) is greater than said determined minimum rotational speed (Smin), controlling the rotational speed (S) of the air compressor (2) based on said only one specific value (S4); h) if a plurality of specific values (S2, S4) is greater than said determined minimum rotational speed (Smin), determining the specific value (S2) with the best efficiency among said plurality of specific values (S2, S4) and controlling the rotational speed (S) of the air compressor (2) based on said specific value (S2) with the best efficiency.

The invention relates to a method for controlling a rotary screw compressor, having at least a first and a second air-end, wherein both air-ends are driven separately from one another and speed controlled. According to the invention, the following steps are carried out: detection of a volume flow taken at the outlet of the second air-end; adjustment of the rotational speed of both air-ends, when the removed volume flow fluctuates in a range between a maximum value and a minimum value; opening of a pressure-relief valve, if the volume flow falls below the minimum value; and reduction of the rotational speed of at least the first air-end to a predetermined idling speed (V1.sub.L) to reduce the volumetric flow delivered by the first to the second air-end.

A method for controlling the speed of a compressor with a controller as a function of the available gas flow comprising the following steps: setting a desired value for the inlet pressure; determining the inlet pressure; determining the speed; controlling the speed of the compressor by reducing or increasing it depending on whether the inlet pressure is less than or greater than the set desired value until the inlet pressure is equal to the set desired value; providing the characteristic data of the compressor relating to the efficiency and/or the Specific Energy Requirement (SER) as a function of the speed and the inlet pressure; adjusting the desired value of the inlet pressure on the basis of the aforementioned characteristic data and in such a way that the efficiency of the compressor is a maximum or the SER is a minimum.

The invention relates to a method for controlling a rotary screw compressor, having at least a first and a second air-end, wherein both air-ends are driven separately from one another and speed controlled. According to the invention, the following steps are carried out: detection of a volume flow taken at the outlet of the second air-end; adjustment of the rotational speed of both air-ends, when the removed volume flow fluctuates in a range between a maximum value and a minimum value; opening of a pressure-relief valve, if the volume flow falls below the minimum value; and reduction of the rotational speed of at least the first air-end to a predetermined idling speed (V1.sub.L) to reduce the volumetric flow delivered by the first to the second air-end.

A pneumatic wrench including a pneumatic motor that includes a rotor, a rotor housing, an endplate, and a wear plate. The rotor has an output shaft configured to rotate about an axis and a plurality of vanes that extend radially from the axis that compressed air exerts work against to drive the rotor. The rotor housing has a cavity configured to house the rotor, receive the compressed air, and direct the compressed air about the rotor and out of the rotor housing. The endplate is coupled to the rotor housing and configured to receive the output shaft. The endplate includes a channel that is in fluid communication with the cavity. The wear plate is disposed between the endplate and the rotor housing and defines an exhaust port between the cavity and the channel for directing airflow from the cavity to the channel in an axial direction.

The invention relates to a method for controlling a rotary screw compressor, having at least a first and a second air-end, wherein both air-ends are driven separately from one another and speed controlled. According to the invention, the following steps are carried out: detection of a volume flow taken at the outlet of the second air-end; adjustment of the rotational speed of both air-ends, when the removed volume flow fluctuates in a range between a maximum value and a minimum value; opening of a pressure-relief valve, if the volume flow falls below the minimum value; and reduction of the rotational speed of at least the first air-end to a predetermined idling speed (V1.sub.L) to reduce the volumetric flow delivered by the first to the second air-end.

Techniques are provided for tuning a rotary positive displacement pump. The techniques include apparatus featuring a signal processor configured to the present invention may take the form of apparatus comprising a signal processor that may be configured to receive signaling containing information about actual pump performance data related to the operation of a rotary positive displacement pump; and determine corrected published pump performance data to operate the rotary positive displacement pump by compensating published pump performance data based at least partly on the actual pump performance data. The corrected published pump performance data may include a corrected published rated power, flow and slip factor, and the actual pump performance data contains information about actual power, specific gravity and viscosity related to the operation of the rotary positive displacement pump and received from a pump controller or controlling device, including a variable frequency drive.

The invention relates to a method for controlling a rotary screw compressor, having at least a first and a second air-end, wherein both air-ends are driven separately from one another and speed controlled. According to the invention, the following steps are carried out: detection of a volume flow taken at the outlet of the second air-end; adjustment of the rotational speed of both air-ends, when the removed volume flow fluctuates in a range between a maximum value and a minimum value; opening of a pressure-relief valve, if the volume flow falls below the minimum value; and reduction of the rotational speed of at least the first air-end to a predetermined idling speed (V1.sub.L) to reduce the volumetric flow delivered by the first to the second air-end.