Abstract: A diaphragm is provided in a pump case so as to define a pump chamber communicated with an external member having an air chamber. A motor actuates the diaphragm to introduce air into the pump chamber and to supply the introduced air to the air chamber. An exhaust valve exhausts air in the pump chamber to lower a pressure in the air chamber. The exhaust valve is provided with a valve body and an actuator which is driven by the motor to actuate the valve body so as to open or close an exhaust port communicated with the pump chamber.

Abstract: A fluid conveyance system includes: a fluid conveyance device including a micro pump module which compresses a flexible tube communicating with a fluid containing receptacle and discharges a fluid, a memory device furnished on the micro pump module which stores individual identification data of the micro pump module, and a power source; a discharge data processing device which stores basic data for driving the fluid conveyance device; and a communication device having a communication unit which interconnects the fluid conveyance device and the discharge data processing device, wherein the discharge data processing device inputs discharge data, for discharging a desired discharge amount of a fluid, calculated from the identification data and the basic data read via the communication device, into the memory device via the communication device, and the fluid conveyance device is driven based on the discharge data.

Abstract: A method of controlling operation of a liquid-fuel combustion appliance. The method is characterized by including an “antiseize operating mode” in which an electric motor and a fuel pump, powered by the electric motor, are started periodically to prevent oxidation and/or polymerization of the liquid fuel in the fuel pump when the fuel pump is idle. More specifically, the fuel pump is a gear pump.

Abstract: An oscillating type piston is connected to an output shaft of an electric motor through a crankshaft. The piston is provided with a lip ring that slidingly contacts a cylinder. The motor is rotated forward and reversely by using a control circuit. Thus, different regions of the piston are subjected to a load during forward rotation of the motor and during reverse rotation thereof. Accordingly, wear of the lip ring can be distributed to different regions thereof.

Abstract: The method of managing time M, at which maintenance of a gas compressor multiple system incorporating therein a plurality of gas compressors should be carried out, involves making a comparison between a value of M and a predetermined time N for necessary maintenance to carry out the maintenance when the value of M is larger than or substantially equal to a value of N, where M is equal to the product of the operating time T of the system, the average load factor L, and a safety factor C.

Abstract: A system and method for diagnosing and protecting a compressor includes a sensor, logic circuitry, a motor protector and an intelligent device. The logic circuitry is associated with the sensor and the motor protector and operable to determine a trip frequency of the motor protector and identify a specific fault cause. The intelligent device communicates with the logic circuitry and indicates the fault cause.

Abstract: A swimming pool backwash control arrangement includes a timing device incorporated with a valve for controlling normal re-circulating flow and backwash flow through a swimming pool filter. The timer is constructed to be in series with the electric power circuit to the pool pump and is activated when the valve is moved to the backwash flow position. The timer functions to maintain electric power to the pump for a user-specified or a pre-set period. At the end of the period the timer will cause the circuit to open thereby disabling the pump. Power can be restored to the pump by returning the valve to its normal re-circulating flow position.

Abstract: A centrifugal fluid pump apparatus includes a control mechanism including an emergency impeller rotation function. The emergency impeller rotation function includes a rotation termination function when the failure detection function detects a failure; impeller magnetic counterforce application function to apply a current to the electromagnet sufficient to overcome the magnetic attraction force of the rotor to the impeller caused by the magnet; hydrodynamic levitation control detection function to detect rotation of the impeller and the rotor by using a motor current monitored by the motor current monitoring function; motor speed control function for increasing the motor speed up to a predetermined value after the hydrodynamic levitation control detection function detects that the hydraulic bearing coupling between the impeller and the rotor has been made; and impeller magnetic counterforce termination function to terminate current to the electromagnet once the predetermined impeller rotation speed is reached.

Abstract: A compressed air system, wherein a decision to de-energize a compressor motor is made with consideration of the likely need for the operation of the compressor at a future point in time. A rate of pressure decay in an air reservoir may be extrapolated over a predetermined time period to predict the need for operation of the compressor within the time period. If operation of the compressor is predicted to be needed within the time period, the compressor is allowed to continue to run in an unloaded mode beyond a normal cool down period.

Abstract: The methods serves for activating an electric motor of a metering pump with which the fluid quantity (Vnom) to be delivered is set by an external impulse trigger, wherein a predetermined delivery quantity (Vnom) is allocated to each impulse (t). The control detects the temporal interval (?t) of the two last-received impulses and activates the electric motor such that the fluid quantity to be delivered, taking the previously evaluated interval as a basis, is distributed over the subsequent impulse interval.

Abstract: A unitary control for operating at least the fan and compressor of a climate control apparatus in response to signals received from a thermostat, the unitary air conditioning control includes a circuit board, a microprocessor on the circuit board; a first relay on the circuit board operable by the microprocessor, to connect a fan connected thereto to line voltage, and having first and second contacts at least one of which is connected to the microprocessor; and a second relay on the circuit board operable by the microprocessor, to connect a fan connected thereto to line voltage, and having first and second contacts connected to the microprocessor.

Abstract: A hot water circulating system to provide instant hot water including a hot water source connected to one or more fixtures and a hot water return line from the fixture to the hot water source including a check valve and a continuous circulation pump in the return line.

Abstract: A controller for controlling the pump unit of an oil well includes a sensor having a first and second probe for placement in the flow of oil from the well bore. Each of the probes contains a heater. A constant power source is selectively connected to one of the heaters. Each of the probes also include a linear RTD at each of their tips respectively for generating a signal indicative of the temperature measured at each of the first and second probes. A control unit receives signals from the RTD's and determines a flow rate therefrom. A pump control signal is generated in response to the flow rate, wherein pump control signal continuously varies a predetermined parameter of a pumping unit during operation of the pumping unit.

Abstract: A compressor assembly having a first compression mechanism operatively coupled to a first motor and a second compression mechanism operatively coupled to a second motor. The first compression mechanism compresses the vapor from a low pressure to an intermediate pressure and the second compression mechanism compresses the vapor from the intermediate pressure to a discharge pressure. An electrical circuit supplies electrical current to the first and second motors during operation of the compressor assembly. The electrical circuit includes means for, during start-up of the compressor assembly, initiating the supply of electrical current to the first motor at a first time and initiating the supply of electrical current to the second motor at a second time wherein the first time precedes the second time by a time lapse.

Abstract: This is a method and means for maintaining a constant supply of a fluid with specific characteristics within a fluid supply conduit from a supply source of the fluid with specific characteristics at a point of service of the fluid with specific characteristics in which a first open end of a recirculation conduit is located within the fluid with specific characteristics supply conduit adjacent the point of service. A second end of the recirculation conduit is connected to pump means in such manner that a portion of the fluid with specific characteristics within the fluid with specific characteristics supply conduit adjacent the point of service is constantly circulated back. In an alternate embodiment a similar recirculation conduit is utilized in a manner to prevent freezing of conduits in a total fluid supply line which includes portions in relatively warm areas and in areas subject to freezing.

Abstract: A method for operating a multi-family/commercial plumbing system includes sensing an event and recording for each sensed event at least one parameter selected from the group consisting of date, day of the week, start time, duration of the event, water flow, water temperature, and humidity. The parameters are analyzed to determine a pattern and thereafter water flow, circulation, water temperature, and water use are controlled in accordance with the determined pattern.

Abstract: A compressor torque estimate device is used for a variable displacement compressor whose displacement is variable based on a compressor control signal for estimating a compressor torque of the compressor. The compressor torque estimate device includes a torque calculator and a corrector. The torque calculator calculates a torque required for driving the compressor based on the compressor control signal, thereby obtaining a calculated torque. The corrector corrects the calculated torque by a procedure of first-order lag, thereby obtaining a corrected torque. The corrector also estimates the corrected torque to be the compressor torque.

Abstract: A pressure sensor subsystem measures the pressure within a fuel pump and outputs an under-pressure signal when the measured pressure is below a predetermined threshold pressure value. A temperature sensor subsystem measures the temperature within the fuel pump and outputs an over-temperature signal when the measured temperature is above a predetermined threshold temperature value. A timing circuit monitors the pressure sensor subsystem and the temperature sensor subsystem for output of the under-pressure and over-temperature signals and outputs a pump disconnect signal when at least one of the signals is output for a prescribed time duration. A power controller disengages power from the pump upon output of a pump disconnect signal by the timing circuit.

Abstract: A system for providing a user with water at a desired temperature comprising a piping system that includes a hot water pipe and a cold water pipe, a pump coupled to the piping system and a smart water delivery device coupled to the piping system and to the pump and operative to allow circulation of water from the hot water pipe to the cold water pipe prior to delivery of water at a desired temperature to the user. The smart water delivery device includes two smart valves coupled to hot and cold water inlets, a smart outlet valve coupled to a device outlet, a microcontroller for controlling the actuation of the pump and of the smart valves, and at least one temperature sensor coupled to the microcontroller and used for sensing the water temperature.

Abstract: A method and apparatus which provides a pressure sensor and/or temperature sensor connected to the low pressure side of a refrigeration system, or the discharge line of a scroll compressor. When the scroll compressor rotates backward, the change of pressure or temperature immediately sends a signal to work with a time-delay relay and a normally closed relay to immediately cut off the electrical power supply to the compressor. Thus, causing the scroll compressor to stop rotating in the undesirable direction.

Abstract: Disclosed are an air conditioning system with two compressors and a method for operating the same, so as to variably change a compression capacity of a refrigerant according to the variation of cooling load. Herein, when a full operation order is inputted to the two compressors in order to satisfy increased cooling load, the first compressor is first operated, and then the second compressor having a compression capacity of a refrigerant smaller than that of the first compressor is additionally operated, so that a current peak value for operating the compressors does not exceed an allowable current range of a circuit breaker installed in a home or building, thereby safely controlling the air conditioning system and simultaneously allowing the current to be provided to other electric appliances, thus improving users' convenience.

Abstract: A free piston gas compressor comprising a cylinder, a piston reciprocable within the cylinder and a reciprocating linear electric motor derivably coupled to the piston having at least one excitation winding. A measure of the reciprocation time of the piston is obtained, any change in the reciprocation time is detected and the power input to said excitation winding is adjusted in response to any detected change in reciprocation time.

Abstract: A transducer calibration apparatus and method for transforming both previously established transducer parameters for a transducer calibrated to a first target object material and measured transducer parameters for the transducer monitoring a second different target object material into a calibration parameter and transforming the output of the transducer and thus, the use of the transducer, from the first target object material used to calibrate the transducer to the second different target object material being subsequently monitored by the transducer by linearizing the output of the transducer into gap values as a function of the calculated calibration parameter and then, generating alarms based on the linearized output of the transducer exceeding established limits and using the alarms to automatically shut down a machine being monitored by the transducer and/or automatically annunciate machine problems to personnel.

Abstract: Disclosed are an apparatus and a method for controlling a plurality of compressors of an air conditioner. The apparatus comprises a counter, a timer, and a controller. The counter serves to count the number of times of operations/stoppages of the plural compressors according to loads. The timer serves to sense a time taken for the plural compressors to be operated/stopped a designated number of times counted by the counter. The controller serves to control the operations of the plural compressors based on the time sensed by the timer. The apparatus senses the time taken for the plural compressors to be operated/stopped the designated number of times, and determines whether or not a load is eliminated based on the sensed time, thereby properly controlling the operations of the compressors. Accordingly, the apparatus of the present invention reduces the consumption of power and increases air conditioning efficiency of the compressors.

Abstract: A method and apparatus for controlling a compressor suitable for delivery of pressurized fluid to a pressurized fluid system, wherein the delivery of the pressurized fluid to the pressurized fluid system can be cycled on and off as a function of a temperature signal received from a temperature sensor. The delivery of pressurized fluid is turned off when the temperature signal exceeds a temperature limit value that is based on the backpressure caused by the pressurized fluid system. Time criteria can be superposed on the temperature limits for controlling the activation and deactivation of the compressor. A preferred area of application of the invention is in vehicle pneumatic suspension systems, including systems having multiple modes of operation.

Abstract: A system and method for reducing the collection of debris in a fluid pumping system. The system and method may be used in pools, spas, or other applications in which fluids are circulated through a fluid-containing vessel. The system includes a first pump that circulates fluid. A screen is coupled to the input of the first pump and acts to prevent debris from reaching the first pump. A second pump may be used to remove debris from the screen.

Abstract: Pumping requirements for chromatograph applications are for constant flow at high and variable pressures and for accurate programmable control of liquid composition. A two-cylinder pump, pumping system, and associated controls provide an accurate, fixed flow rate. A low pressure gradient former controls composition. During the initial portion of the pumping stroke of a first piston in which fluid is being compressed due to its finite bulk modulus of elasticity its check valve remains closed, a second piston provides all the flow required at a fixed rotational speed. Then, once the first piston has reached its bottom dead center, the control system switches to a constant-pressure control mode, thereby maintaining the flow rate at a fixed value. Constant-pressure control is again switched off either when the second piston's discharge check valve closes, or when the second piston's inlet check valve opens, and pump control returns to fixed rotational speed.

Abstract: A system and method for reducing the collection of debris in a fluid pumping system. The system and method may be used in pools, spas, or other applications in which fluids are circulated through a fluid-containing vessel. The system includes a first pump that circulates fluid. A screen is coupled to the input of the first pump and acts to prevent debris from reaching the first pump. A second pump may be used to remove debris from the screen.

Abstract: A method for controlling a hybrid compressor system is disclosed. The hybrid compressor system includes a variable displacement hybrid compressor that is selectively driven by one of an engine and an electric motor to cool a passenger compartment of a vehicle. The method includes the steps of transmitting a demand signal to activate an electric motor drive mode of the hybrid compressor system, whereby the electric motor drives the hybrid compressor, transmitting a compressor displacement signal to the hybrid compressor to set a displacement of the compressor to a minimum level, waiting a predefined time period, activating the electric motor to drive the compressor, determining a suction pressure of a suction chamber of the hybrid compressor, determining whether the displacement of the hybrid compressor is sufficient based on the suction pressure determination, and changing the displacement of the compressor if the displacement is insufficient.

Abstract: A bilge pump having a mounting member adapted to be mounted to a vessel and a base movably engageable with the mounting member and positionable in at least two positions relative to the mounting member. A housing is releasably coupled to the base and defines a cavity for receiving a motor. A locking ring is engageable with the motor and the housing to secure the motor in the cavity while allowing the motor to be movable with respect to the housing. The cavity in the housing communicates with an outlet portion defining a socket. An outlet nozzle having an outlet end is movably received in the socket so that the outlet end can be moved relative to the housing. These features can be employed individually or in combination to make the bilge pump highly adaptable, thereby facilitating installation.

Abstract: There is provided an emergency motor shut off for a closed air system having a low pressure threshold and a high pressure threshold. In a preferred embodiment, the closed air system includes a compressor and motor for charging the pressure of the system. Typically, any suitable electric power source provides power to the motor. A pair of electric contactorss electrically disposed between the power source and the motor are pneumatically controlled to allow electric current to either pass through or to prevent current from reaching the motor. A timer determines the run time for a single run cycle of the motor. A shut off that is responsive to the timer impedes the flow of electric current to the motor after a predetermined amount of run time. The timer is reset to zero after each run cycle of the motor. Typically the shut off comprises a relay timer having an internal relay. The invention also provides for an alarm to signal when the system when the predetermined amount of time is reached on the timer.

Abstract: Motor speed, motor amps, float position and elapsed run time are monitored to determine whether a sump pump is in a normal condition, a jammed condition, an inadequate pumping rate condition, a dry running condition or a stuck float condition. A processor is configured to increase the motor speed in response to an inadequate pumping rate condition, and to rapidly energize the motor clockwise and counterclockwise in response to a jammed condition or a stuck float condition. The processor provides signals to a display for displaying information about the condition that the pump is in. The pump is set up to receive power from either an AC power source or a battery power source. Availability of the AC power source is monitored and the pump is switched to operate from the battery power source when AC power is unavailable.

Abstract: A method for controlling the operation of one or more electrically-operated pumps (11, 12) to pump a liquid from a well or sump (10) which, in use, receives a substantially continuous inflow of said liquid, characterized in that the method includes the step of starting or stopping each pump in relation to the approach of a change of tariff for the electricity supplied for the operation of each said pump (11, 12).

Abstract: A system and method for controlling a compressor (1) is provided that prevents the piston (5) of the compressor from colliding against the valve system (8, 9) provided therein. The system and method of the present invention control the stroke of the piston (5), allowing the piston (5) to advance as far as the end of its mechanical stroke in extreme conditions of load, without allowing the piston (5) to collide with the valve system (8,9). The present invention controls the compressor (1) by measuring a movement time of the piston (5); comparing the movement time with a foreseen movement time; and altering the voltage (Vm) if the first movement time is different from the foreseen movement time, the foreseen movement time being such that the movement of the piston (5) will reach a maximum point (M).

Abstract: Improved method for cleaning a pump, fluid hose, and spray gun is provided by, for example, repeatedly changing the flow rate of the cleaning fluid pumped through the system to generate turbulence or increased turbulence and increased frictional resistance for enhanced cleaning action. A pressure control can cyclically vary the speed of the pump motor and pump connected thereto to generate the turbulence. The pumping cycle can alternate between a first and second power level and at a desired time interval for each speed. With a suitable solvent as the pumped fluid, the turbulence that is generated by the cyclical pumping action causes an increase in the scrubbing action of the solvent to quickly loosen residual material in the fluid passageways.

Abstract: In a vehicle air conditioner, a control unit includes determining means for determining a first start of a compressor for compressing refrigerant in a refrigerant cycle after being mounted on the vehicle, and control means for controlling operation of the compressor so that the compressor is operated for a predetermined time by a rotation speed equal to or lower than a predetermined rotation speed when the determining means determines the first start of the compressor. Accordingly, breaking-in operation of the compressor can be accurately performed for the predetermined time by an automatic control.

Abstract: A pneumatic pump control system for sequentially switching on and off an electrically operated pump disposed in a waste water liquid storage tank The pneumatic pump control system comprises a pneumatic pressure accumulator that is disposed within the liquid storage tank at a predetermined level. The pneumatic pressure accumulator is a dome-type that defines an interior air chamber for containing air, and a lower opening disposed at an elevation that represents a zero reference level within the tank. The lower opening is in communication with the liquids in the liquid storage tank when the level of liquid is as high as the lower opening. A pressure transducer is operatively connected to the pneumatic pressure accumulator for communication with the interior air chamber to measure the differential air pressure between the air within the interior air chamber and the upper layer of air within the liquid storage tank.

Abstract: A method and apparatus which provides a pressure sensor and/or temperature sensor connected to the low pressure side of a refrigeration system, or the discharge line of a scroll compressor. When the scroll compressor rotates backward, the change of pressure or temperature immediately sends a signal to work with a time-delay relay and a normally closed relay to immediately cut off the electrical power supply to the compressor. Thus, causing the scroll compressor to stop rotating in the undesirable direction.

Abstract: A semiautomatic electronic system for sensing and accordingly raising if such is determined to be required, the fluid level of a liquid present in swimming pools, animal water drinking troughs, or any other liquid containment vessels. For the accomplishment of this task an electronic circuit periodically, in accordance with a schedule prescribe by a user, samples the environment of the space in a liquid containment vessel to determine if a liquid level has fallen below a predetermine level prescribed by the user. If such is the case, either a pump or a solenoid valve can be automatically activated, so as to cause liquid to be added to the containment vessel, only until the liquid in the containment vessel is restored to the required predetermined level.

Abstract: A pump-off control system for use with an electric motor driven pump jack assembly for operation of a down hole pump in which a circuit interrupter device is attached to the top of the polished rod of the pump jack and upon occurrence of fluid pound, the polished rod imparts sufficient force on the circuit interrupter device to open the electrical contacts of the device momentarily interrupting power to the electric motor shutting down the pump for a period of time determined by a time delay relay that controls the shut down time for the well.

Abstract: A pump-off control system for use with an electric motor driven pump jack assembly for operation of a down hole pump in which a circuit interrupter device is attached to the top of the polished rod of the pump jack and upon occurrence of fluid pound, the polished rod imparts sufficient force on the circuit interrupter device to open the electrical contacts of the device momentarily interrupting power to the electric motor shutting down the pump for a period of time determined by a time delay relay that controls the shut down time for the well.

Abstract: A vacuum management and regeneration apparatus and method for operating an energy storage flywheel system having a flywheel supported by a bearing system inside an evacuated chamber enclosed within a container. A motor/generator stores and retrieves energy by accelerating and decelerating the flywheel. A vacuum is maintained in the container with a vacuum level sufficient to reduce the aerodynamic drag on the flywheel, typically between 10−1 Torr to 10−3 Torr depending on the flywheel construction and its operating tip speed. The vacuum management system, including a vacuum pump and a timer, maintains the vacuum level in the container. The timer periodically enables operation of the vacuum pump, such as a mechanical vacuum pump or a getter pump, to reduce the pressure in the container.

Abstract: A washing appliance having a thermally actuated diverter valve to allow for the diversion of water through the water holding receptacle of the washing appliance, where control means controls the turning on and off of an inlet valve and energizing of the thermally actuated diverter valve. A method of controlling a thermally activated valve in the cycle of the washing appliance is also disclosed. This method provides for the operation of a thermally actuated diverter valve during a recirculation wash phase in a washing appliance. The present invention allows for the thermally actuated diverter valve's “on time” life to be conserved, particularly in situations where the flow of water into the appliance is low, for example when the appliance is used in areas where water pressure is low, or when valves or pipes are blocked or obscured.

Abstract: The modular timer for an air circulator comprises a timer for energizing an air circulator motor for a predetermined amount of time. A first connector connects the timer to an air circulator motor while a second connector connects the timer to a power switch. A selection switch controls the timer setting of the timer such that the time period corresponds to at least one time period of a work shift. A housing limits access to the selection switch and protects it.

Abstract: A pump assembly for a pressurized water system includes a pressure sensitive switch (27) arranged to monitor the water pressure in a pipe (14) extending between a water delivery pump (13) and a tap (15), the switch (27) controlling operation of the pump (13) dependent upon pressure in the pipe (14). A timer switch (30) is disposed in series with the pressure sensitive switch (27), to inhibit pump operation other than for a limited period of time following triggering of the timer switch (30).

Abstract: A bilge pump having a mounting member adapted to be mounted to a vessel and a base movably engageable with the mounting member and positionable in at least two positions relative to the mounting member. A housing is releasably coupled to the base and defines a cavity for receiving a motor. A locking ring is engageable with the motor and the housing to secure the motor in the cavity while allowing the motor to be movable with respect to the housing. The cavity in the housing communicates with an outlet portion defining a socket. An outlet nozzle having an outlet end is movably received in the socket so that the outlet end can be moved relative to the housing. These features can be employed individually or in combination to make the bilge pump highly adaptable, thereby facilitating installation.

Abstract: A fan assembly includes a first fan and a second fan. The first fan has a first housing and a first blade assembly. The first blade assembly includes a plurality of blades attached to a hub, and is configured to rotate about a first axis of rotation in a first direction. The second fan includes a second housing and a second blade assembly. The second blade assembly also includes a plurality of blades attached to a hub. The second blade assembly, however, is configured to rotate about a second axis of rotation in a second direction that is opposite the first direction of rotation. The first axis of rotation and the second axis of rotation can be coincidental or they can be slightly offset.

Abstract: An electronic control system dynamically varies the output capacity of a compressor by controlling plural valves associated with the compressor to provide pressurized air to a distribution system at an appropriate rate. The control system operates in any of three modes for standalone operation, including continuous run, auto/dual pressure band, and target pressure modes. In the first two modes, pressure bands are dynamically calculated based on load and unload values entered by an operator. These electronic control systems can also be connected in a peer-to-peer network to coordinate control of up to 16 compressors feeding the same distribution system, so as to maintain a desired target pressure in the system. A modem connected to the system supports remote diagnostics, monitoring, and control. Specialized startup, operating, and shutdown diagnostic algorithms prevent damage to the compressor and avert unsafe operating conditions.

Abstract: Provided is a low-noise, long-life electromagnetic blower that has a simple, low-priced configuration and can realize two different outputs, high and low. When the electromagnetic blower is operated with low output, coils of an electromagnet are connected in series with each other, and an alternating current is supplied from an AC power source. When the blower is operated with high output, on the other hand, current is supplied to the one coil only. In the case where the electromagnetic blower is used for sewage disposal, the electromagnetic blower is operated with low output during aeration and with high output during reverse cleaning operation. Thereupon, the electromagnetic blower can operate with low noise during aeration, and the efficiency of reverse cleaning can be improved. In order to operate the electromagnetic blower with high output, moreover, the coils of the electromagnet may be connected in parallel with each other.

Abstract: A system and method for controlling a compressor (1) is provided that prevents the piston (5) of the compressor from colliding against the valve system (8, 9) provided therein. The system and method of the present invention control the stroke of the piston (5), allowing the piston (5) to advance as far as the end of its mechanical stroke in extreme conditions of load, without allowing the piston (5) to collide with the valve system (8,9). The present invention controls the compressor (1) by measuring a movement time of the piston (5); comparing the movement time with a foreseen movement time; and altering the voltage (Vm) if the first movement time is different from the foreseen movement time, the foreseen movement time being such that the movement of the piston (5) will reach a maximum point (M).