An electric oil pump device includes an electric oil pump driven by a motor and a microcomputer that adjusts a control parameter of feedback control related to a motor current value or a motor rotation speed based on an oil temperature estimated based on a relationship between at least one of a hydraulic pressure, the motor current value, or a torque of the electric oil pump and at least one of an oil discharge amount or the motor rotation speed of the electric oil pump.

Provided is an air compressor improved in terms of reliability by taking into consideration of the condensation of the water vapor in the compressed air. According to the present invention, an air compressor includes: a compressor main body; a compression chamber of the compressor main body compressing sucked-in air; an oil supply port supplying a lubricating oil to the compression chamber; an oil separator separating compressed air discharged from the compression chamber and the lubricating oil from each other; oil temperature adjustment means adjusting temperature of the lubricating oil supplied to the oil supply port; control means controlling the oil temperature adjustment means; sucked-in air temperature detection means detecting temperature of the sucked-in air; and sucked-in air humidity detection means detecting humidity of the sucked-in air, wherein the oil temperature adjustment means is controlled on the basis of detection information of the sucked-in air temperature detection means and of the sucked-in air humidity detection means.

A compressor may include a shell containing a motor, a compression mechanism and a lubricant sump. The compressor may also include first and second temperature sensors, and a control module. The first temperature sensor may be at least partially disposed within the lubricant sump and may measure a first temperature of a lubricant at a first position. The second temperature sensor may be at least partially disposed within the lubricant sump and may measure a second temperature of the lubricant at a second position that is vertically higher than the first position. The control module is in communication with the first and second temperature sensors. The control module may determine a first difference between the first temperature and the second temperature. The control module may determine whether a liquid level of the lubricant in the lubricant sump is below a predetermined level based on the first difference.

A compressor includes a shell, a first temperature sensor, a second temperature sensor, and a control module. The shell includes a motor, a compression mechanism and a lubricant sump. The first temperature sensor is at least partially disposed within the shell and configured to measure a first temperature of a lubricant at a first position. The second temperature sensor is at least partially disposed within the shell and configured to measure a second temperature of the lubricant at a second position that is vertically higher than the first position. The control module is in communication with the first and second temperature sensors and configured to determine a first difference between the first temperature and the second temperature. The control module is configured to determine whether a liquid level of the lubricant in the lubricant sump is below a predetermined level based on the first difference.

A mixing valve arrangement for a hydraulic system is provided with a medium cavity, in which a mixing cylinder, a first and a second inlet chamber as well as an outlet are provided. A mixing piston is axially mounted and movable in the mixing cylinder, provided with a flow path with an inlet opening, a variable cross-section of said inlet opening culminating into the first and/or the second inlet chamber, according to the axial position of the mixing piston, and with an outlet opening culminating in the outlet of the mixing cylinder. A thrust rod is axially mounted and movable and connected to the mixing piston, to change the axial position thereof. A drive is connected as an actuator to the thrust rod, for the axial movement of the same. The drive is an electrical motor, which is completely arranged inside the medium cavity.

A compressor may include a shell, a compression mechanism, first and second temperature sensors, and a control module. The shell may define a lubricant sump. The compression mechanism may be disposed within the shell and may be operable to compress a working fluid. The first temperature sensor may be at least partially disposed within the shell at a first position. The second temperature sensor may be at least partially disposed within the shell at a second position that is vertically higher than the first position. The control module may be in communication with the first and second temperature sensors and the pressure sensor and may determine whether a liquid level in the lubricant sump is below a predetermined level based on data received from the first and second temperature sensors.

A system includes a sensor and a controller for a refrigeration or HVAC system having a compressor. The sensor senses a temperature of the compressor during operation of the compressor. The controller is configured to determine a rate of change of the temperature relative to time and to perform one or more procedures to protect the compressor based on the rate of change of the temperature. The one or more procedures to protect the compressor include shutting down the compressor, throttling a pressure regulator valve of an evaporator associated with the compressor, adjusting an expansion valve associated with the evaporator, reducing speed of the compressor, and partially or wholly unloading the compressor.

The present disclosure provides a compressor system operable for compressing a working fluid such as air. A conditioner is positioned upstream of the compressor to reduce the humidity and in some embodiments may control a temperature of the working fluid entering the compressor. A working fluid aftercooler and a lubricant cooler is positioned downstream of the compressor. A first heat exchange system directs water from a source through the conditioner and then to the aftercooler and oil cooler in parallel. A second heat exchange system directs oil from the compressor to the oil cooler and then to a regenerator prior to reentry into the compressor. A control system with one or more control valves is configured to provide oil to the compressor at a target temperature defined to ensure that the temperature of the discharged compressor is above a pressure dew point temperature.

A compressor may include a shell containing a motor, a compression mechanism and a lubricant sump. The compressor may also include first and second temperature sensors, and a control module. The first temperature sensor may be at least partially disposed within the lubricant sump and may measure a first temperature of a lubricant at a first position. The second temperature sensor may be at least partially disposed within the lubricant sump and may measure a second temperature of the lubricant at a second position that is vertically higher than the first position. The control module is in communication with the first and second temperature sensors. The control module may determine a first difference between the first temperature and the second temperature. The control module may determine whether a liquid level of the lubricant in the lubricant sump is below a predetermined level based on the first difference.

An arrangement (100) for specifying the pressure (64), produced by a pump (30) driven by an electric motor (31), includes a processor (116) which derives a target pressure value (64, 118) from an internal torque value (114) and a loss torque (108). The arrangement (100) further derives (112) the internal torque value (114) from a motor current value (110) and a motor constant k.sub.e.