The present invention relates to rotary screw positive displacement machines used as a vacuum pump wherein additional intake air is provided allowing cooling to the invention which permits extended operation at extreme vacuum pressure. The rotary screw nature of the vacuum pump allows operation without additional lubrication with the additional intake air ensuring that thermal expansion will not disrupt the tight tolerances of the invention. The invention allows simultaneous operation as a vacuum pump and air compressor.

The present invention relates to rotary screw positive displacement machines used as a vacuum pump wherein additional intake air is provided allowing cooling to the invention which permits extended operation at extreme vacuum pressure. The rotary screw nature of the vacuum pump allows operation without additional lubrication with the additional intake air ensuring that thermal expansion will not disrupt the tight tolerances of the invention. The invention allows simultaneous operation as a vacuum pump and air compressor.

A hydraulic pump is described, comprising at least one inlet duct for a fluid, at least one outlet duct for the fluid and at least one pumping unit interposed between the inlet and outlet ducts. At least one multifunction valve is interposed between the inlet duct, upstream of the pumping unit, and the outlet duct, downstream of the pumping unit, which valve is configured to divert the flow of fluid from the inlet duct to the outlet duct without the fluid flowing into the pumping unit. The multifunction valve comprises a valve body that defines an inner bypass channel in which a shutter element is axially movable, an actuator member operatively associated with the shutter element and configured to move it from a closing position to an opening position of the bypass channel, and an elastic contrast element operatively associated with the shutter element and configured to keep it in the first closing position of the bypass channel when such shutter element is not actuated by the actuator member. The actuator member consists of a bias spring manufactured with a shape memory alloy, configured to move the shutter element from the first closing position to the second opening position of the bypass channel when a predefined temperature value is reached.

The present invention relates to a redundant vacuum pumping system (300) and a pumping method using this system, comprising a primary roots pump (302), a first pumping sub-system (310) and a second pumping sub-system (320), wherein the first pumping sub-system (310) and the second pumping sub-system (320) are arranged to pump in parallel the gas evacuated by the primary roots pump (302), the first pumping sub-system (310) comprising a first secondary roots pump (311) and a first positive displacement pump (312) and a first valve (313) positioned between the gas discharge outlet (302b) of the primary roots pump (302) and the gas suction inlet (311a) of the first secondary roots pump (311), and the second pumping sub-system (320) comprising a second secondary roots pump (311) and a second positive displacement pump (312) and a second valve (323) positioned between the gas discharge outlet (302b) of the primary roots pump (302) and the gas suction inlet (321a) of the second secondary roots pump (321). According to the invention, the first pumping sub-system (310) and the second pumping sub-system (320) are configured to pump at a same flow rate, and the primary roots pump (302) is configured to be able to pump at a flow rate F equal to the pumping flow rate of the primary pumping sub-system (310) plus the pumping flow rate of the secondary pumping sub-system (320).

In a method for operation control of a compressor, full-load running in which a gas intake control valve is fully open and a target rotation speed of a drive source is set to a full-load rotation speed that is a maximum rotation speed in a speed control band when pressure of compressed gas supplied to the consumption side is a datum pressure or less is carried out; then no-load running in which the valve is fully closed and a no-load rotation speed is set as the target rotation speed of the drive source when the supply pressure is a no-load running pressure or less that is a pressure higher than the datum pressure is carried out. The no-load running is started from the standard no-load rotation speed, however, after a transition time, the target rotation speed is reduced to a low speed no-load rotation speed.

In a method for operation control of a compressor, full-load running in which a gas intake control valve is fully open and a target rotation speed of a drive source is set to a full-load rotation speed that is a maximum rotation speed in a speed control band when pressure of compressed gas supplied to the consumption side is a datum pressure or less is carried out; then no-load running in which the valve is fully closed and a no-load rotation speed is set as the target rotation speed of the drive source when the supply pressure is a no-load running pressure or less that is a pressure higher than the datum pressure is carried out. The no-load running is started from the standard no-load rotation speed, however, after a transition time, the target rotation speed is reduced to a low speed no-load rotation speed.

The present invention is directed to a minimum pressure valve comprising a housing (13) with a valve inlet (11) and a valve outlet (12) which are connected by means of a chamber (16), said minimum pressure valve (10) further comprising a valve body (17) movable in said chamber (16) between a closed position in which said valve inlet (11) is closed off, and an open position in which said valve inlet (11) is open, whereby said minimum pressure valve (10) further comprises a regulation unit (18) for setting the value of the pressure at which the valve body (17) moves into an open position.

The present invention is directed to a minimum pressure valve comprising a housing (13) with a valve inlet (11) and a valve outlet (12) which are connected by means of a chamber (16), said minimum pressure valve (10) further comprising a valve body (17) movable in said chamber (16) between a closed position in which said valve inlet (11) is closed off, and an open position in which said valve inlet (11) is open, whereby said minimum pressure valve (10) further comprises a regulation unit (18) for setting the value of the pressure at which the valve body (17) moves into an open position.

Power systems and methods of controlling an engine driven air compressor include an air compressor driven by an engine via a clutch. A first pressure sensor configured to sense a pressure level at an outlet of the air compressor. An inlet valve configured to close in response to the first pressure sensor sensing a pressure level above a first pressure level. In addition, a second pressure sensor to sense a pressure level below a second pressure level at a housing of the air compressor, wherein the clutch is configured to disengage in response to the second pressure level, wherein the first pressure level is higher than the second pressure level.

Power systems and methods of controlling an engine driven air compressor include an air compressor driven by an engine via a clutch. A first pressure sensor configured to sense a pressure level at an outlet of the air compressor. An inlet valve configured to close in response to the first pressure sensor sensing a pressure level above a first pressure level. In addition, a second pressure sensor to sense a pressure level below a second pressure level at a housing of the air compressor, wherein the clutch is configured to disengage in response to the second pressure level, wherein the first pressure level is higher than the second pressure level.