Abstract: A cartridge hand pump is disclosed. The cartridge hand pump comprises a housing; a lever extending from the housing; a cylinder provided in the housing wherein the cylinder is connected to a supply passage for receiving hydraulic fluid and to an actuator passage for sending pressurised hydraulic fluid; and a piston slidably positioned in the cylinder, the piston being operably connected to the lever for movement between a first position and a second position wherein the movement of the piston from the first to the second position sends pressurised fluid to the actuator passage characterised by a pressure relief valve accommodated in the housing wherein the pressure relief valve is in communication with the actuator passage such that pressurised hydraulic fluid is discharged through the pressure relief valve when pressure in the actuator passage exceeds a predetermined value.

Abstract: Providing pressurized fracturing fluid with a fracturing pump transport comprising a first fracturing pump and a second fracturing pump that are coupled on opposite sides of a dual shaft electric motor. A first drive line assembly comprising a first engagement coupling that allows for selective engagement and/or disengagement of the first fracturing pump with the dual shaft electric motor. A second drive line assembly comprising a second engagement coupling that allows for selective engagement and/or disengagement of the second fracturing pump with the dual shaft electric motor. The fracturing pump transport also comprising an engagement panel that allows for selective engagement or disengagement at the first engagement coupling based on receiving a remote command.

Abstract: An electro hydrostatic actuator system for retracting/extending a landing gear includes a plurality of hydraulic actuators, a plurality of hydraulic supply sources each including a single hydraulic pump and a single electric motor, provided in parallel to each other and joined at the downstream ends, a plurality of switching valves provided in parallel on a supply path that connects the hydraulic actuators to a junction of the hydraulic supply sources, and a controller configured to sequentially operate the hydraulic actuators. The hydraulic supply sources each include a check valve which prevents operation oil from flowing toward the hydraulic pump. In a normal state, the hydraulic supply sources together supply operation oil sequentially to the hydraulic actuators. When any of the hydraulic supply sources is failed, the other hydraulic supply source(s) other than the failed hydraulic supply source supplies operation oil sequentially to the hydraulic actuators.

Abstract: An industrial fluid circulating system having at least one fluid circulation circuit, includes a plurality of pumps connected in parallel to circulate the fluid through each of the fluid circulation circuit, a separate motor driving each pump, a load detector to sense operating loads on the system and each circuit, and a speed control to vary the speed of each motor to thereby vary the pumping capacity of each pump in response to the detected load on the system, each pump of each respective circuit running simultaneously at a substantially similar speed or a predetermined equal reduced speed of the respective circuit or an almost equal reduced speed or a similar reduced speed.

Abstract: A cooling system includes a fan group with a number of fans arranged in a row, a rail extending in a direction parallel to the row of the fans. A backup fan slidably mounted to the rail, a motor configured to control the movement of the backup fan, and a control board to determine whether there exists one malfunction fan in the fan group. When one abnormal fan exists in the fan group, the control board outputs a control signal to the motor, to enable the motor to drive the backup fan to move to a location corresponding to the abnormal fan.

Abstract: The invention relates to a separable device for the application of compression and thermal therapy to a patient. A first section includes a reservoir, liquid pump and a thermal exchange system for the application of thermal therapy as well as a dock. The second section of the device includes an air compressor and at least one controller for the application of compression therapy and can be operated independently from the first section. Additionally, the second section may be engaged with a dock of the first section.

Abstract: Pumping systems and methods for delivering a plurality of different pumpable materials serially at a location at substantially the same flow rate includes a plurality of diaphragm pumps, wherein each diaphragm pump has a first chamber for receiving a hydraulic fluid from a first and/or second hydraulic fluid source and a second chamber for receiving a material to be pumped from one of a plurality of pumpable material sources. A sensor is provided for detecting the pressure of the hydraulic fluid in each of the first chambers of the plurality of diaphragm pumps and is operable to activate the source of hydraulic fluid to ensure that the hydraulic fluid in each of the first chambers of the plurality of diaphragm pumps has an equivalent pressure.

Abstract: An apparatus for generating negative pressure in an installation for filling containers with liquid bulk product includes a vacuum device, and a control-and-regulating unit. The vacuum device has a controllable suction power, and has a plural electrically-powered vacuum pumps. These are configured to operate in parallel. The control-and-regulating unit is configured to control the number of vacuum pumps that are active, thereby controlling the suction power.

Abstract: Provided are sampling pumps and gas analyzers using the sampling pumps. The sampling pump may include at least one reciprocating pump set and a control system. Each reciprocating pump set can include two reciprocating pumps. The control system can output drive signals for controlling reciprocating drawing and compressing operations of the reciprocating pumps, where the control system may be designed to output the drive signals that cause the two reciprocating pumps within the same set to provide opposing impact directions at the same time.

Abstract: The invention relates to a wind turbine being provided with a fluid displacement means for ensuring a certain increased pumping capacity at a certain reduced rotational speed of the main shaft of the rotor and thus of a drive shaft from a gear box of the wind turbine. The invention also relates to a wind turbine being provided with fluid displacement means for ensuring a certain increased pumping capacity at a certain increased rotational speed of the main shaft of the rotor and thus of a drive shaft from a gear box of the wind turbine. The means may be mechanical, hydraulic, pneumatic or electrical. Additionally, the invention relates to a method for operating a wind turbine being provided with such fluid displacement means.

Abstract: A hydraulic power device for effecting operation of at least one load, the hydraulic power device including a motor having a predetermined motor speed rating and motor power rating, at least one pump operably coupled to the motor, the pump being configured to provide, to the at least one load, a predetermined hydraulic fluid flow at the predetermined motor speed rating, and a variable frequency drive connected to the motor, the variable frequency drive being configured to effect operation of the motor at a speed above the predetermined motor speed rating such that the at least one pump operates to provide an excess hydraulic fluid flow during operation of the motor substantially above the predetermined motor speed rating where the excess fluid flow is greater than the predetermined hydraulic fluid flow.

Abstract: A vehicle control system includes: a power unit including an engine and a rotating electrical machine; a power supply apparatus connected to the rotating electrical machine; an oil pump unit including a mechanical oil pump and an electric oil pump for cooling the rotating electrical machine; and a control apparatus. The control apparatus is constituted by an EOP idling determination unit that determines an idling state of the electric oil pump, and an engine starting processing unit that performs processing to drive the mechanical oil pump by starting the engine in accordance with the determination of the EOP idling determination unit.

Abstract: For refrigeration units, maintenance machines are required that can receive and compress the refrigerant from the refrigeration unit. Furthermore, a vacuum pump is required, which is connected to the emptied lines and pumps out humidity and air. The maintenance machine according to the invention includes a motor that drives a compressor via a freewheel in one rotational direction. The same motor drives a vacuum pump via a second freewheel in the other rotational direction. The maintenance machine, which can perform two different functions, includes only one single motor. The machine is lightweight, so that it can be carried by the maintenance personnel. Furthermore, it is small and can be produced in a cost-effective manner.

Abstract: The invention is an apparatus and method of varying power output and decrease noise generation of spa pumps by powering them with a variable frequency power device, digital signals capable of controlling cascaded pumps using ganged controls, and to decrease safety concerns of spas using an integrated water level and motion detectors.

Abstract: A fluid supply apparatus which supplies fluid to a medical apparatus includes: a pump mechanism including a first pump capable of a suction operation of the fluid after a feeding operation of the fluid, and a second pump capable of a suction operation of the fluid during the feeding operation and a feeding operation of the fluid during the suction operation; a flow path which includes an elastic member and which communicates with the first pump and the second pump and supplies the fluid to the medical apparatus; and a flow path deforming unit which deforms a part of the flow path. The flow path deforming unit starts first deformation of the flow path before the first pump switches from the feeding operation to the suction operation, and completes the first deformation and starts second deformation of the flow path during the feeding operation by the second pump.

Abstract: A pump apparatus configured with a first pump for pumping working fluid in accordance with a reciprocation of a piston using a space between a first open/close valve for suction and a second open/close valve for discharge as a pump chamber. The pump apparatus is also configured a first flow passage for supplying the working fluid from a supply source to an operation subject via the first open/close valve, the pump chamber, and the second open/close valve in accordance with an operation of the first pump. A second flow passage supplies the working fluid pumped by a second pump, which is different from the first pump, to the pump chamber. A selector is configured to select either the first flow passage or the second flow passage.

Abstract: A fan system includes: two circuit breakers, a control module for controlling two circuit breakers, two electric motors to which their operating voltage UB is supplied via the circuit breakers, and at least one temperature sensor on a board on which the circuit breakers are located. The control module evaluates a signal TNTC from the temperature sensor, and sets the pulse duty factors TV1, TV2 of pulsed control voltages at the circuit breakers, while taking into account this signal as well as a requested fan power, in such a way that no power loss PV exceeding a specified value occurs at any circuit breaker.

Abstract: An oil pump unit with a variable flow rate includes lubrication pumps and a control pump that are driven by rotation of a crankshaft of an engine, and changes an oil supply amount from the control pump to each part of the engine, in which the control pump includes a plurality of oil pumps that have different discharge rates.

Abstract: The invention relates to a vacuum generator module comprising a substantially rectangular box housing: the pneumatic vacuum generator means and their channels for connection to an admission orifice for admitting a gas under pressure, to a gas exhaust orifice, and to a suction orifice, each orifice opening to the outside via one of the faces of the box; and electronic means for controlling and monitoring the operation of the pneumatic means and their electrical connections with an electrical power supply and external control members using a defined program, including two connectors, one being an input connector, and the other being an output connector likewise installed in one of the faces of the box; the set being characterized in that: the electronic means comprise a multi-network I/O microcontroller suitable for imparting a master or slave function to the module depending on whether the module is or is not directly connected to a fieldbus present in a vacuum handling machine incorporating the module.

Abstract: A fan array fan section in an air-handling system includes a plurality of fan units arranged in a fan array and positioned within an air-handling compartment. One preferred embodiment may include an array controller programmed to operate the plurality of fan units at peak efficiency. The plurality of fan units may be arranged in a true array configuration, a spaced pattern array configuration, a checker board array configuration, rows slightly offset array configuration, columns slightly offset array configuration, or a staggered array configuration.

Abstract: A counter-rotating axial-flow fan may be controlled to improve both cooling efficiency and operating efficiency. A first motor and a second motor are started in a given starting mode. Then, if the temperature of an object to be cooled is higher than a given reference temperature, the rotational speed of the first motor and the rotational speed of the second motor are controlled in a predetermined cooling efficiency mode that gives priority to cooling the object to be cooled over the operating efficiency of the counter-rotating axial-flow fan. If the temperature of the object to be cooled is equal to or lower than the given reference temperature, the rotational speeds of the first and second motors are controlled in a predetermined operating efficiency mode that maintains the object to be cooled at a temperature equal to or lower than the given reference temperature and reduces the power consumption of the counter-rotating axial-flow fan.

Abstract: A sealed compressor has an outer housing and a separator plate received within the outer housing. The separator plate defines a suction chamber and a discharge pressure chamber within the outer housing. A locating plate is positioned within the suction pressure chamber. The locating plate has a plurality of positioning locations for receiving separate compressor housings. The separator plate has a plurality of positioning openings for receiving the separate compressors. A plurality of compressors are each received within their own housing, and include compressor pump units. The plurality of compressors extend between the openings in the locating plate and through the openings in the separator plate. The separate compressors deliver compressed refrigerant into the discharge pressure chamber.

Abstract: A fuel supply installation for a turbojet including two volumetric pumps for combining their flow rates is disclosed. The pumps include a main pump dimensioned for the full gas rate and an auxiliary pump controlled and dimensioned to provide the supplementary flow rate necessary on ignition.

Abstract: A refrigeration device includes an interior that is divided up into two refrigeration zones with each refrigeration zone having an evaporator and a compressor for supplying the evaporator with a refrigerant. A control for operating the compressors can be operated in different modes of operation depending on predetermined conditions. In a normal mode, the at least two compressors are exclusively operated at different times.

Abstract: A compressor assembly includes at least two tandem compressors. Tandem compressors have at least one common suction manifold, communicating a source of working fluid to be compressed by each of at least two compressors, and at least one common discharge manifold communicating a compressed fluid downstream for further use. A common intermediate pressure manifold communicates with intermediate pressure ports in at least two compressors. The intermediate manifold may communicate fluid to or out of the at least two compressors. There is normally no direct communication between suction and discharge manifolds.

Abstract: A variable displacement rotary pump includes a main pump unit, an auxiliary pump unit, a discharge passage, a bypass passage, a suction passage, a check valve and a control valve. The suction passage is in communication with the discharge passage through the bypass passage and a second discharge port. The check valve is disposed in the discharge passage for preventing fluid in a first discharge port of the main pump unit from flowing into the bypass passage. The control valve is operable for opening and closing the bypass passage. When the control valve opens the bypass passage and the check valve closes the discharge passage, flow rate of the fluid discharged from the discharge passage is reduced. A throttle passage is provided in the bypass passage or the control valve for regulating flow of the fluid in early phase of operation of the control valve to open the bypass passage.

Abstract: A controller for a system having at least one variable-capacity, pulse-width modulated compressor and at least one fixed-capacity compressor is provided. The controller may include processing circuitry that modulates the at least one variable-capacity, pulse-width modulated compressor to any capacity substantially between ten percent capacity and one hundred percent capacity. The processing circuitry may determine a desired capacity of the at least one variable capacity, pulse-width modulated compressor based on a load sensor signal and a current run percentage of the at least one variable capacity, pulse-width modulated compressor and may toggle the at least one fixed-capacity compressor between a run mode and a shutdown mode based on the desired capacity of the at least one variable-capacity, pulse-width modulated compressor.

Abstract: The present invention comprehends a gerotor or gear pump driven by a permanent magnet motor which exhibits cogging torque, i.e., resistance to rotation when de-energized caused by interaction between permanent magnets in the rotor and teeth on the stator. Such interaction causes the rotor to come to rest in one of many defined rotational positions and resist rotation when electrical power to the motor has been terminated. The permanent magnet motor is coupled, preferably directly, to a gerotor pump having meshing rotors or a gear pump having meshing gears. When the motor is de-energized, the pump rotors or gears come to rest and their rotation is resisted by the cogging torque of the motor. The invention finds particular application in automotive transmissions and systems with parallel pumps.

Abstract: A multi-stage compression installation is formed of a main pipe (2) emerging in a baffle plate (3), where at least two compressors (4, 5) are mounted in series each having its own drive member (9, 10). The installation is equipped with a system for determining the pressure at the output of the main pipe (2), the installation being connected to a control box (8). Typically, the control box (8) is connected to at least two of the drive members (9, 10) of the compressors (4, 5) and ensures monitoring of the compressors such that the latter rotate jointly whether charged or uncharged. Thus, the compressors (4, 5) are jointly charged based on the pressure prevailing in the baffle plate (3), such that the charging of the compressor representing the overpressure stage, the compressor(s) of the lower compression stages are automatically and jointly charged.

Abstract: A marine vessel control apparatus is arranged to start and stop engines that are respectively provided in multiple propulsion devices. The marine vessel control apparatus includes multiple individual start/stop switches arranged to correspond to the respective multiple propulsion devices and arranged to be operated by an operator to individually start and stop the engines in the respective multiple propulsion devices, an all-device start/stop switch arranged to be operated by the operator to collectively start and stop the engines in the multiple propulsion devices, an operating state acquiring unit arranged to acquire operating states of the engines in the respective multiple propulsion devices, and a control unit. The control unit includes multiple input ports corresponding to the respective multiple individual start/stop switches. Each of the input ports is connected with the corresponding individual start/stop switch. All of the input ports are connected commonly with the all-device start/stop switch.

Abstract: A sealed compressor has an outer housing and a separator plate received within the outer housing. The separator plate defines a suction chamber and a discharge pressure chamber within the outer housing. A locating plate is positioned within the suction pressure chamber. The locating plate has a plurality of positioning locations for receiving separate compressor housings. The separator plate has a plurality of positioning openings for receiving the separate compressors. A plurality of compressors are each received within their own housing, and include compressor pump units. The plurality of compressors extend between the openings in the locating plate and through the openings in the separator plate. The separate compressors deliver compressed refrigerant into the discharge pressure chamber.

Abstract: Optimisation of components of a fuel supply installation for a turbojet. The installation comprises two volumetric pumps for combining their flow rates, a main pump (14) dimensioned for the full gas rate and an auxiliary pump (16) controlled and dimensioned to provide the supplementary flow rate necessary on ignition.

Abstract: Apparatus for maintaining differential internal fluid pressure in a dual fluid chamber object where it is desired for one chamber to have greater internal pressure than the other includes a sensor for generating a differential signal indicating the difference in pressure between the chambers, a pressure sensor for generating a pressure signal indicating the pressure inside the chamber desired to have less pressure, a comparator for generating a first output when the differential signal is less than a predetermined minimum differential value, a second comparator for generating a second output when the pressure signal is less than a predetermined minimum pressure value, where the predetermined minimum pressure value biased by the first output, and blowers coupled to the respective chambers and responsive to said first and second outputs respectively.

Abstract: Method for adjusting a compressed air installation using several electrically driven compressors of what is called the “loaded/unloaded” type and/or the turbo compressor type and/or the compressor type with variable rotational speed, wherein these compressors are each connected to a single compressed air network with their outlets, and wherein use is made of a control box which makes it possible to adjust the pressure in the compressed air network around a target pressure to be set. The adjustment takes place by controlling the flow of one or several of the compressors, in particular in order to increase the overall flow supplied by the compressors when the pressure drops too much, and in order to lower the overall supplied flow when the pressure becomes too high.

Abstract: A fan array fan section in an air-handling system includes a plurality of fan units arranged in a fan array and positioned within an air-handling compartment. One preferred embodiment may include an array controller programmed to operate the plurality of fan units at peak efficiency. The plurality of fan units may be arranged in a true array configuration, a spaced pattern array configuration, a checker board array configuration, rows slightly offset array configuration, columns slightly offset array configuration, or a staggered array configuration.

Abstract: A compressor control system includes at least one variable compressor, at least one fixed-capacity compressor, and a controller. The controller modulates the variable compressor based on a suction pressure reading of the variable compressor. In addition, the controller selectively toggles the fixed-capacity compressor between a run mode and a shutdown mode based on an operating parameter of the variable compressor.

Abstract: A fan array fan section in an air-handling system includes a plurality of fan units arranged in a fan array and positioned within an air-handling compartment. One preferred embodiment may include an array controller programed to operate the plurality of fan units at peak efficiency. The plurality of fan units may be arranged in a true array configuration, a spaced pattern array configuration, a checker board array configuration, rows slightly offset array configuration, columns slightly offset array configuration, or a staggered array configuration.

Abstract: A control apparatus for controlling two oil pumps which are provided on a vehicle wherein the two oil pumps are selectively driven by respective different drive power sources such that one of the two oil pumps is operated while the other oil pump is held at rest, the control apparatus including an air removal control portion configured to temporarily operate the above-indicated other oil pump during an operation of the above-indicated one oil pump, to remove air staying at and around an oil inlet of the above-indicated other oil pump.

Abstract: An electronic system, an apparatus for cooling an electronic system, an electronics cooling apparatus, and associated method use a clutch to operate a cooling fan. An electronics cooling fan for usage in cooling an electronic system comprises a clutch that disengages upon failure wherein the electronics cooling fan is configured to freewheel upon disengagement of the clutch.

Abstract: The invention relates to a pump assembly for the synchronous pressurization of two fluid circuits. Two internal gear pumps are disposed together in a pump housing and rotationally driven by drive shafts thereof. Pinions of the pumps are located in an associated pump chamber and engage in an internal gear thereof. The pump chambers of the internal gear pumps are separated from each other by a common separating wall or partition, which is designed as a separate housing part and engages in a hollow cross-section of a housing part forming the circumferential wall of one of the internal gear pumps. Suction channels and pressure channels associated with the internal gear pumps transition into a radially extending longitudinal section in the pump housing following an axial longitudinal section in the lateral boundary wall of the associated pump chamber. According to the invention, a suction channel and a pressure channel of one of the internal gear pumps are integrated in the separating wall.

Abstract: A system for cancelling or attenuating noise in at least two positive displacement compressors proximately located from each other for use with a heating or cooling system. A lead compressor and a lag compressor have a controllable rotational speed and phase of operation. A controller selectably controls the rotational speed and the phase of operation of each of the compressors. The controller controls the rotational speed of the compressors at substantially the same speed for each compressor, with a phase-lock loop and a comparator circuit for each compressor. The controller controls the phase of operation of the compressors through an oscillator so that the lead and lag compressor pressure pulses are spaced between successive outlet pressure pulses to effectively double the combined pulsation frequency for noise attenuation.

Abstract: A modular system for the control of at least one compression system for the compression a fluid medium, said compression system comprising compressors (C1-C7) and their controllers (A1-A7) for the compression of the fluid medium, secondary treatment devices for the treatment of the medium delivered from the compressors, and piping systems (17-19, 23) for conducting the fluid medium to a place of consumption (16, 22), said control system comprising a control unit (3) containing a data processing system (34) for controlling the compression system, a user interface (35) including a display associated with it and transmission means for the transmission of control data between the control unit, the controllers and pressure sensors. The transmission means consist of data communication buses, preferably serial communication buses (30-32) and a data communication port unit (33) serving to connect the bus to the control unit (34). The controllers and pressure sensors are connected to common data communication buses.

Abstract: A downhole pump assembly for removing volumes of liquids, crude oils, gases, and produced waters, from oil or gas wells is described based on a downhole controllable electric drive, and a positive displacement pump, wherein the electric drive powers a hydraulic pump that powers the positive displacement pump.

Abstract: A method for optimizing the operation of several compressor units in a natural gas compression station. After a second or further compressor unit is started, the speeds of the running compressor units are set according to a fixed speed ratio in relation to characteristic data established for each compressor unit. The fixed speed ratio is altered by adjusting the rate of flow to the same percentage via the speed of rotation until the preventive pump valves of the gas compressor station are closed, whereupon the operating points of the compressor units are guided, where possible, in the characteristic data thereof, to the maximum efficiency. The optimum set speed values are determined according to continuous operating characteristics of the gas compression station by coordinated variation of the set speeds of the compressors, taking into account fuel consumption of the gas compression station. The stored fixed speed ratio is adjusted according to the optimum set speed values thus determined and stored.

Abstract: A blower unit for generating air for cooling a heat exchanger includes a plurality of blowers, a single motor, a driving shaft, gears, gear boxes and a joint. The blowers are arranged in parallel with each other with respect to a flow of air passing through the heat exchanger. The driving shaft extends from the motor and is connected to rotation shafts of the blowers through the gears. The gear boxes house the gears therein and support the driving shaft and the rotation shafts of the blowers to be rotatable. The driving shaft is divided into a plurality of shaft parts in a longitudinal direction thereof. The adjacent shaft parts are connected to each other through the joint.

Abstract: A hydraulic system for an electro-mechanical transmission includes an electrically-powered main pump, a battery powered auxiliary pump and an output pump. The main pump provides fluid to transmission components such as a torque-transmitting mechanism. The auxiliary pump provides fluid pressure to engage the torque-transmitting mechanism when electric power to the main pump is unavailable or the main pump is otherwise inoperable. The engaged torque-transmitting mechanism enables rotation of an output member which mechanically powers the output pump so that it may provide fluid to the transmission components in lieu of the main pump. A method of providing fluid to transmission components is also provided.

Abstract: Insulating oil in electric power generation, transmission and distribution equipment such as circuit breakers, regulators, phase shifters, tank diverter switches and capacitor banks for respectively separated phases of a plural phase transmission or distribution line is filtered for removal of accumulated water, carbon particles and other contaminants by filters in oil circuits respective to each phase in the plurality. Each oil circuit respective to each circuit breaker includes a respective filter and circulation pump. However, all pumps in the plural phase power system, for example, are driven by the same motor and drive line whereby a fluid condition or circulation interruption of one oil circuit that requires termination of pump operation in the one oil circuit terminates the pump operation in all oil circuits. Pump motor power is preferably drawn from an energy source that may be independent of that served by the transmission and/or distribution power source.

Abstract: A fan array fan section in an air-handling system includes a plurality of fan units arranged in a fan array and positioned within an air-handling compartment. One preferred embodiment may include an array controller programmed to operate the plurality of fan units at peak efficiency. The plurality of fan units may be arranged in a true array configuration, a spaced pattern array configuration, a checker board array configuration, rows slightly offset array configuration, columns slightly offset array configuration, or a staggered array configuration.

Abstract: A system is provided for attenuating noise in at least two positive displacement compressors proximately located from each other for use with at least one heating or cooling system. A lead compressor and a lag compressor have a selectably controllable rotational speed and a selectably controllable phase of operation. A controller selectably controls the rotational speed and the phase of operation of each of the compressors. The controller controls the rotational speed of the compressors at a predetermined rotational speed that is substantially the same for each of the compressors. The controller controls the phase of operation of the compressors by shifting the phase of operation of the lag compressor so that an outlet pressure pulse operatively produced by the lag compressor is substantially evenly spaced between successive outlet pressure pulses operatively produced by the reference compressor.

Abstract: A compressor system includes a pair of compressors located in a common shell. A common drive shaft drives both compressors and the drive shaft is powered by a single motor. One or both of the compressors can be equipped with a pulse width modulated capacity control system and a vapor injection system. When one compressor is equipped with these systems, the capacity can be varied between 50% and 110%. When both compressors are equipped with these systems, the capacity can be varied between 0% and 120%.