Even when abnormal heat generation occurs during operation in a state where the temperature of a compressor is not increased, abnormality cannot be detected. A fluid machine includes a fluid machine body; a motor that drives the fluid machine body; a temperature sensor that measures a temperature of the fluid machine body; and a control unit that controls the fluid machine body. The control unit changes a temperature threshold value based on at least one of a pressure of a fluid discharged by the fluid machine body and a frequency of a voltage input into the motor, and issues a notification when the temperature of the compressor body measured by the temperature sensor exceeds the temperature threshold value.

A thrust vector control system is provided. The thrust vector control system may comprise an anti-stall hydraulic pump configured to deliver hydraulic fluid to at least one actuator, wherein each actuator may be configured to move an exhaust nozzle of a space vehicle. The anti-stall hydraulic pump may provide thermal conditioning to the thrust vector actuation control system during ground operation and/or periods of low output operation.

Surgical systems can include evacuation systems for evacuating smoke, fluid, and/or particulates from a surgical site. A surgical evacuation system can be intelligent and may include one or more sensors for detecting one or more properties of the surgical system, evacuation system, surgical procedure, surgical site, and/or patient tissue, for example.

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.

Control systems and methods for increasing efficiency of a compressor while the compressor capacity exceeds compressor load, by using a mechanical unloader such as a slide valve to reduce the internal volume ratio of the compressor and allow a more efficient speed to be maintained by a variable frequency drive (VFD) while reducing the compressor capacity based on the load. Control systems include the VFD, a controller for the VFD and the mechanical unloader, and temperature sensors. Compressor embodiments further include one or more compressors and mechanical unloaders operated by the control systems.

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.

In order to reduce operation in a rotation-prohibited frequency range and to prevent resonance in a gas compressor wherein inverter control is performed, this gas compressor has: a compressor main body that compresses a gas; a motor that rotationally drives the compressor main body; an inverter that changes the rotational speed of the motor; a check valve arranged downstream from the compressor main body; a pressure detection means that detects load-side pressure downstream from the check valve; and a control device that, in accordance with the pressure detected by the pressure detection means, controls the frequency output by the inverter. The control device performs a control whereby compressed gas having a prescribed pressure is generated/maintained by increasing/decreasing the frequency, and when the frequency that generates the compressed gas having the prescribed pressure includes a specific frequency, the inverter's output frequency is increased or decreased when the pressure detected by the pressure detection means reaches a pressure corresponding to a frequency that has a more constant pressure width than the prescribed pressure and does not include the specific frequency.

Device for controlling the oil temperature of an oil-injected compressor installation (1) with a compressor element (2) that is provided with a gas inlet (3) and an outlet (5) for compressed gas that is connected to an oil separator (8) that is connected by means of an injection pipe (12) to the aforementioned compressor element (2), and whereby a cooler (17) is affixed in a part (19) of the injection pipe (12) that can be bypassed by means of a bypass pipe (18), characterised in that the device (20) is provided with an extra pipe (21) that is intended to be connected in parallel with the bypass pipe (18) and the cooler (17), and in which an energy recovery system (22) can be connected, and that the device (20) is provided with flow distribution means (23) through the cooler (17), the bypass pipe (18) and the extra pipe (21), and a controller (28) for controlling these temperature (T.sub.out) control means at the aforementioned outlet (5) of the compressor element (2).

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 thrust vector control system is provided. The thrust vector control system may comprise an anti-stall hydraulic pump configured to deliver hydraulic fluid to at least one actuator, wherein each actuator may be configured to move an exhaust nozzle of a space vehicle. The anti-stall hydraulic pump may provide thermal conditioning to the thrust vector actuation control system during ground operation and/or periods of low output operation.