Most multistage compressors specify a maximum inlet pressure that may be supplied to the compressor to stay within designed limits. If the supply gas to be compressed is at a higher pressure than the specified maximum inlet pressure, then its pressure must be reduced before connecting it to the compressor. This pressure reduction is inefficient. The present invention avoids reducing the inlet pressure by routing the supply gas directly to the appropriate compression stage depending on its inlet pressure such that the compressor loads are still within the specified limits of the equipment.

Most multistage compressors specify a maximum inlet pressure that may be supplied to the compressor to stay within designed limits. If the supply gas to be compressed is at a higher pressure than the specified maximum inlet pressure, then its pressure must be reduced before connecting it to the compressor. This pressure reduction is inefficient. The present invention avoids reducing the inlet pressure by routing the supply gas directly to the appropriate compression stage depending on its inlet pressure such that the compressor loads are still within the specified limits of the equipment.

A method for operating a pressure control system having a multi-stage compressor includes providing a multiply compressed pressure medium by the multi-stage compressor for filling a pressure medium reservoir or pressure medium chambers of the pressure control system. Providing the multiply compressed pressure medium includes (i) providing, by a first compression stage, a pre-compressed pressure medium and additionally compressing, at least by a second compression stage, the pre-compressed pressure medium, and/or (ii) introducing an already-compressed charging pressure medium into an intermediate volume between the first compression stage and the second compression stage of the multi-stage compressor and further compressing the charging pressure medium at least by the second compression stage. The charging pressure medium simultaneously passes via a control line to a control input of a shut-off valve that interacts with the first compression stage, such that a charging pressure of the charging pressure medium predefines a control pressure.

The inflating device has a body, a large cylinder, a small cylinder, a handle, a switching mechanism, and a switching device. The large cylinder is mounted moveably in the body and has an upper input gap, an inner bottom base, and a bottom base. The upper input gap is defined between an outer surface of a bottom end of the large cylinder and an inner surface of a first chamber of the body. The bottom base is connected with the large cylinder, is located below the inner bottom base, and has a first annular holding recess and a first O-ring. The small cylinder is mounted moveably in a second chamber of the large cylinder and has a piston base. The handle is mounted on the top end of the small cylinder. The switching mechanism is mounted on the top end of the large cylinder.

A variable-capacity compressor that includes a housing having an inlet for receipt of refrigerant and an outlet for return of refrigerant, and a plurality of compressing elements contained in the housing between the inlet and the outlet. The variable capacity compressor includes a valve having an electrical control. The valve is dedicated to fewer than all of the compressing elements. The valve is movable between a first state which communicates refrigerant flow to the compressing elements, and a second state that reduces or stops flow to the compressing elements. In an embodiment of the invention, an unloading controller has an operational modulation mode that includes cycling the valve between on and off states to provide a portion of compressor capacity. The unloading controller is further programmed to provide a minimum delay time between transitions between the first and second states, but no maximum dwell time between transitions.

A variable-capacity compressor that includes a housing having an inlet for receipt of refrigerant and an outlet for return of refrigerant, and a plurality of compressing elements contained in the housing between the inlet and the outlet. The variable capacity compressor includes a valve having an electrical control. The valve is dedicated to fewer than all of the compressing elements. The valve is movable between a first state which communicates refrigerant flow to the compressing elements, and a second state that reduces or stops flow to the compressing elements. In an embodiment of the invention, an unloading controller has an operational modulation mode that includes cycling the valve between on and off states to provide a portion of compressor capacity. The unloading controller is further programmed to provide a minimum delay time between transitions between the first and second states, but no maximum dwell time between transitions.

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.

Systems and methods of the invention relate to monitoring a change in a rotational speed of a crankshaft to identify a failure related to a crankcase breather valve. A reciprocating compressor can include a detection component that is configured to track a rotational speed of a crankshaft of a compressor to identify a change in rotational speed. In an embodiment, the rotational speed can be monitored while unloaded and/or below approximately 800 Revolutions Per Minute (RPM). Based on a change in a rotational speed of the crankshaft, a controller can be configured to communicate an alert which corresponds to a failure related to the crankcase breather valve.

Systems and methods of the invention relate to monitoring a change in a rotational speed of a crankshaft to identify a failure related to a crankcase breather valve. A reciprocating compressor can include a detection component that is configured to track a rotational speed of a crankshaft of a compressor to identify a change in rotational speed. In an embodiment, the rotational speed can be monitored while unloaded and/or below approximately 800 Revolutions Per Minute (RPM). Based on a change in a rotational speed of the crankshaft, a controller can be configured to communicate an alert which corresponds to a failure related to the crankcase breather valve.

The present disclosure relates to a reciprocating-piston compressor (10), including a control device (12), which control device is designed to control a flow rate of the reciprocating-piston compressor (10), in particular in a continuously variable manner, and which control device has an input (18) for feeding input information, in particular suction pressure or high pressure of a corresponding compressor (10), and has at least one output (20) for controlling a control element (16), wherein the control device (12) is designed to generate a digital output signal, wherein the control element has a digitally controllable control valve (16), wherein the reciprocating-piston compressor (10) has at least one suction-gas volume (22) and at least one high-pressure volume (24), wherein a connection (26) is formed between the at least one suction-gas volume (22) and the at least one high-pressure volume (24) of the reciprocating-piston compressor (10), wherein the digitally controllable control valve (16) is arranged in the connection (26), wherein the reciprocating-piston compressor (10) has a shut-off device, in particular a valve, further in particular a check valve (28), which is arranged downstream of the high-pressure volume (24), as regarded in a flow direction of the refrigerant during normal operation of the reciprocating-piston compressor (10), wherein the at least one suction-gas volume and the at least one high-pressure volume and the control valve (16) are integrated into the reciprocating-piston compressor (10). The disclosure further relates to a refrigerating or air-conditioning installation or heat pump having a corresponding compressor (10), and to a corresponding control method.