Abstract: An apparatus and system for manipulating the air temperature within an interior compartment of a vehicle, the apparatus and system includes a HVAC system and an operating system. A compressor receives and circulates a gas through a heat exchanger in order to regulate the air within the vehicle. The compressor has a capacity control valve that is manipulated by the control system in response to a user setting.

Abstract: A compressor and oil separator assembly for compressing a fluid includes a suction end, a discharge end, and first and second rotors rotatably mounted between the suction and discharge ends. A discharge line communicates with the discharge end, and an oil separator communicates with the discharge line. An oil sump communicates with the oil separator and an oil supply line communicates between the oil sump and the rotors. A bleed line selectively communicates between the discharge line and the oil supply line for equalizing a pressure differential between the suction end and the discharge end without causing substantial backward rotation of the rotors or displacement of oil to the rotors through the oil supply line. Preferably, the assembly further includes a valve that defines a portion of the discharge line and is also coupled to the bleed line.

Abstract: A refrigeration chiller employs a centrifugal compressor the impellers of which are mounted on a shaft which is itself mounted for rotation using rolling element bearings lubricated only by the refrigerant which constitutes the working fluid of the chiller system. Apparatus is taught for providing liquid refrigerant to (1.) the bearings immediately upon chiller start-up, during chiller operation and during a coastdown period subsequent to shutdown of the chiller and (2.) the drive motor of the chiller's compressor for motor cooling purposes. By use of a variable speed-driven motor to drive the compressor, optimized part load chiller performance is achieved in a chiller which does not require or employ an oil-based lubrication system.

Abstract: A combination sight glass and optical sensor is provided in the housing of a hermetic compressor to provide effective visual inspection in addition to automatic sensing of the level of oil in an oil sump. A sight glass fitting is provided in the housing and has a first portion that extends outwardly from the housing and that is accessible from outside the compressor. An optical oil level sensing device is removably attached to the first portion of the sight glass with electrical leads extending outside the compressor for connection to a compressor controller. A prism or similar device is attached to the sight glass fitting intermediate the sump oil and the optical sensor. The sensing device includes a light source, a photosensitive detector, and an opaque member to prevent cross coupling between the light source and the detector.

Abstract: In a refrigerant cycle system for a vehicle air conditioner, when a continuous operation time of a compressor elapses a predetermined time after the compressor operates, operation of the compressor is forcibly interrupted so that a refrigerant pressure at a suction side of the compressor is changed. Thus, even when the compressor operates continuously in a long time when only a front evaporator operates among front and rear evaporators, the refrigerant pressure at a low-pressure side is forcibly changed so that a rear thermal expansion valve of the rear evaporator is forcibly opened. As a result, lubrication oil staying in the rear evaporator and a low-pressure pipe is introduced into the suction side of the compressor by a refrigerant flow due to a valve opening of the rear thermal expansion valve of the rear evaporator.

Abstract: In a compression type refrigeration system having a volatile refrigerant circulating along with lubricating oil, member for causing oil to flow from a first location to a second location, where the member comprises an educator connected to receive the oil from the first location, a high pressure source within the system connected to the educator, and a connection from the eductor to the second location.

Abstract: Lubrication supply to the rotors of a variable speed screw compressor is optimized for full load and a supplemental supply path is provided which is opened during low speed operation.

Abstract: A refrigeration chiller employs a centrifugal compressor the impellers of which are mounted on a shaft which is itself mounted for rotation using rolling element bearings lubricated only by the refrigerant which constitutes the working fluid of the chiller system. Apparatus is taught for providing liquid refrigerant to (1.) the bearings immediately upon chiller start-up, during chiller operation and during a coastdown period subsequent to shutdown of the chiller and (2.) the drive motor of the chiller's compressor for motor cooling purposes. By use of a variable speed-driven motor to drive the compressor, optimized part load chiller performance is achieved in a chiller which does not require or employ an oil-based lubrication system.

Abstract: In a compressor of a refrigeration cycle using an HC-based refrigerant and a lubricant having specific gravity greater than that of the HC-based refrigerant and having no or no or less mutual solubility with the HC-based refrigerant, an oil reservoir is formed on a bottom of the compressor, the oil reservoir is provided at its portion with a recess, a suction port of a lubricant suction pipe for supplying the lubricant to a compressor mechanism is provided in the recess. With this feature, it is possible to sufficiently supply the lubricant to the compressor even when the lubricant has no or less mutual solubility, so that even if the amount of the lubricant is reduced, the lubricant can be sufficiently sucked from an inlet port of a lubricant pumping pipe and supplied to the compressor mechanism.

Abstract: A sensor system. The system comprises a binary sensor issuing a signal representative of a first or second condition; sampling circuitry, operatively connected to the binary sensor, for monitoring the number of transitions between the first and second conditions during a sampling period; integration circuitry for accumulating the sampled number of transitions over time; and signal generation circuitry for issuing an analog signal representative of the accumulated transitions.

Abstract: A method for operating a motor vehicle air conditioner includes starting a compressor, and lubricating the compressor with a circulating lubricant for at least a specified minimum lubricating time.

Abstract: The invention is a method and apparatus for cooling compressor oil in a refrigeration system by passing the oil through a heat exchanger cooled by evaporating refrigerant. The refrigerant is pumped into the heat exchanger by a liquid refrigerant pump. The use of the pump avoids the requirement of a mixing pipe with an internal venturi nozzle, while also providing oil-cooling that is relatively free of noise and disturbance to those in the vicinity of the refrigeration unit.

Abstract: A capacity type refrigerant compressor having a compression chamber in which a refrigerant introduced from a suction system is compressed and discharged as a compressed high pressure refrigerant, and an oil-separating and lubricating system for lubricating an interior of the compressor by an oil separated from the compressed refrigerant, which has an oil-separating unit to separate the oil from the compressed refrigerant, an oil-storing chamber storing the separated oil, an oil-supply passage to supply the oil from the oil-storing chamber to the suction system, a pressure-operated valve arranged in the oil supply passage to regulate an amount of flow of the oil, which includes a valve chamber and a movable valve spool in the valve chamber to control a communication between the upstream and downstream of the oil-supply passage.

Abstract: This oil level control device is for a refrigeration system, the control device being attached between the compressor and the oil supply. The control device includes a housing having an inlet communicating with the oil supply and an outlet communicating with a compressor sump; and a solenoid valve controlling flow from the oil supply into the compressor sump. A sensing chamber having a fixed probe providing a proximity detection system detects the oil level in the sump and responds to a change in the complex permittivity of the oil as the oil level rises and falls to generate a signal that controls the supply of oil to maintain the oil level in the compressor. Circuitry is provided having an input connected to the output of the sensor and an output connected to the solenoid valve.

Abstract: An assured supply of lubricant to the compressor in a refrigeration chiller is provided by a reservoir that is connected in parallel with the main line by which lubricant is supplied to the compressor. The reservoir is connected to the main lubricant supply line in a manner such that if the lubricant supply line is blown dry, as can occur as a result of an unusual or abnormal chiller shutdown condition, a critical portion of the supply line will be refilled by the reservoir relatively very quickly which assures the immediate availability of lubricant to the compressor from that portion of the lubricant supply line when it next starts up.

Abstract: Responsive to a request for refrigeration, a start up sequence is initiated and, if start up is achieved, a number of motor and compressor parameters of operation are sensed for controlling and protecting the compressor. Depending upon the nature of the sensed conditions, if necessary, the motor, and thereby the compressor, is either disabled or corrective action is initially taken to bring the parameters within an acceptable range. If corrective action is ineffective, the motor and thereby the compressor, is disabled.

Abstract: A compressor for use in a refrigerator, which has a rotary shaft supported by bearings to be lubricated by a liquid refrigerant and is adapted to permit the rotary shaft to continue rotating for a while after a liquid refrigerant pump is stopped at, for example, a power failure, thereby preventing the bearings from being damaged. To that end the compressor has a reservoir liquid tank for storing high pressure liquid refrigerant to be supplied to the bearing and a gas storage tank for storing high pressure gas. There is a valve system connected between the gas storage tank and the reservoir liquid tank which is operable upon a power failure to supply high pressure gas to the liquid storage tank.

Abstract: A refrigerating cycle apparatus including an inverter driven compressor with controllable speed of rotation, a four-way valve, an indoor heat exchanger, a pressure reducing device, outdoor heat exchanger, a defrosting condition detector for detecting a frosting state of the outdoor heat exchanger in a heating operation, a defrosting operation controller for carrying out a defrosting operation based on a detection signal from the defrosting condition detector and having a minimum operable frequency controller for controlling a minimum operable frequency for the compressor on restarting after completion of the defrosting operation and/or a starting speed controller for controlling a starting speed for the compressor based on a detection signal from the defrosting condition detector on restarting after completion of the defrosting operation in order to provide proper lubrication after a defrost operation.

Abstract: A compressor (30) for use in a refrigerator, which has a rotary shaft (33) supported by bearings (39 to 42) to be lubricated by a liquid refrigerant and is adapted to permit the rotary shaft 33 to continue rotating for a while after a liquid refrigerant pump (36) is stopped at, for example, a power failure, thereby preventing the bearings (39 to 42) from being damaged. To that end, the compressor (30) is further provided with a header (52) for storing a predetermined amount of a high-pressure liquid refrigerant, and with check valves (51, 54 and 56) for maintaining the internal pressure of this header (52) at a high pressure for a predetermined time period after a power failure occurs.

Abstract: A method for controlling oil viscosity in a refrigeration unit having an oil viscosity effecting parameter with a desired set point. The refrigeration unit includes an oil lubricated compressor having a capacity and a suction pressure, a condenser, refrigerant control valves, and an evaporator connected in series, for circulating a refrigerant for adjusting air temperature of a compartment.

Abstract: An oil level regulator is disclosed for use in a refrigeration system which has an oil reservoir and at least one compressor with a crankcase for containing oil. The regulator has a body with an interior fluid chamber for receiving oil. An inlet communicates with the fluid chamber of the body and is connected by a conduit to the oil reservoir of the system. An outlet communicates from the fluid chamber through a conduit through to the crankcase of the compressor. A level detecting mechanism is disposed within the fluid chamber for detecting an oil level therein. The level detector mechanism includes a solenoid assembly which is actuated by the detector mechanism when the oil level within the chamber is determined to be at or below a predetermined level. A microprocessor is provided on the regulator which communicates with the detector mechanism and the solenoid assembly.

Abstract: An automotive air conditioner which is capable of suppressing periodic torque variation in an engine-driven refrigerant compressor while ensuring performance of returning oil thereto to circumvent periodic variation in a rotational speed of an engine, thereby preventing degradation in motor power performance and drivability of an automobile. A value of target blowout temperature is calculated using a set temperature, indoor air temperature, outdoor air temperature and intensity of solar radiation. A value of first target post-evaporation temperature (TEO1) is calculated according to a determined value of target blowout temperature. Then, a value of second target post-evaporation temperature (TEO2) corresponding to a limit level for ensuring oil return performance is calculated according to the outdoor or indoor air temperature.

Abstract: A protection system for a compressor. The system comprises a compressor having a discharge and including at least one rotor and at least one bearing; a lubrication system including at least one oil recovery device for recovering oil from the compressor, and further including bearing conduit connecting the oil recovery device to the compressor bearing and including rotor conduit for connecting the oil recovery device to the compressor rotors; and an oil protection system. The oil protection system includes a compressor discharge temperature sensor located in the discharge for sensing the temperature of a lubricant/refrigerant mixture discharged by the compressor, a differential pressure sensor located in the bearing conduit for measuring a differential pressure in the bearing conduit, and an oil detector located in the rotor conduit for detecting the presence of oil in the rotor conduit.

Abstract: A compressor (30) for use in a refrigerator, which has a rotary shaft (33) supported by bearings (39 to 42) to be lubricated by a liquid refrigerant and is adapted to permit the rotary shaft 33 to continue rotating for a while after a liquid refrigerant pump (36) is stopped at, for example, a power failure, thereby preventing the bearings (39 to 42) from being damaged. To that end, the compressor (30) is further provided with a header (52) for storing a predetermined amount of a high-pressure liquid refrigerant, and with check valves (51, 54 and 56) for maintaining the internal pressure of this header (52) at a high pressure for a predetermined time period after a power failure occurs.

Abstract: A climate controller for an automobile, comprising a compressor and a receiver arranged in an engine compartment of the automobile, a condenser located at an outside-air inlet of the engine compartment, an expansion member and an evaporator disposed in a passenger compartment of the automobile, and a closed-loop refrigerant passage connecting the compressor, the condenser, the receiver, the expansion member and the evaporator in sequence for circulating a refrigerant through these components to establish a refrigerating cycle. The climate controller further includes a valve arranged in a part of the closed-loop refrigerant passage extending from the evaporator through the compressor to the condenser. The valve is actuated to intersect a communication of the refrigerant through the part of the passage when an operation affecting temperature of both the compressor and the condenser becomes ineffective, and to allow the communication when the operation becomes effective.

Abstract: To exercise control so that, when power is restored in the case of there having been a prower cut, the motor does not run simultaneously with other devices which reqire large amounts of power when starting to run. This invention there is provided improved freezer control unit, which exercise to ccntrol by providing power cut detector 10, which detects that the power source which drives freezer 5 has undergone a power cut, and stopping the signal of signal holding circuit 4, which outputs the `Run` signal, by the signal of this power cut detector 10 when a power cut occurs so that freezer 5 does not restart automatically when power is restored.

Abstract: An optical liquid level sensor for distinguishing between the presence of oil and vapor within a compressor crankcase. The sensor has a light transmitting window positioned to interface the crankcase interior and a planar side facing the crankcase exterior. A light source and a light sensor are both positioned adjacent the exterior face of the window. The sensor has a first condition when the prismatic face is immersed in oil and a second condition when the prismatic face is immersed in vapor. An electronic circuit having a dual MOSFET switch for alternating current is mounted adjacent the light source and sensor. The circuit provides power to the source and monitors the sensor. When the sensor is in the first condition, the circuit closes the switch. When the sensor detects the second condition, the circuit starts a timer and continuously tests the condition of the sensor. If the first condition is detected, the timer resets to its initial value.

Abstract: The present invention is a method for controlling oil lubricant pressure of a screw type compressor in an air conditioning system. In response to a low oil pressure condition, evaporator pressure is lowered to increase the pressure differential across a compressor, to thereby bring about an increase in oil pressure. Evaporator pressure can be lowered by decreasing the maximum operating pressure of the evaporator, and by throttling an expansion valve by the amount required to lower the evaporator pressure in accordance with the reduced maximum operating setpoint.

Abstract: Two outdoor units (2A, 2B) are connected in parallel to a main liquid line (7L) and a main gas line (7G). Three indoor units (3A, 3B, 3C) are connected in parallel to the main liquid line (7L) and the main gas line (7G). The outdoor units (2A, 2B) are each provided with an oil equalization mechanism (9A, 9B) for conducting a surplus out of lubricating oil stored in an oil reserving part (91) provided on the discharge side of a compressor (21) to the suction side of a compressor (21) of another outdoor unit (2A, 2B). In cooling operation, the respective oil equalization mechanisms (9A, 9B) control respective gas bypass passages (95, 96) and respective oil equalizing bypass pipes (93, 94) to open and close them so that lubricating oil flows alternately between the outdoor units (2A, 2B), thereby equalizing lubricating oil.

Abstract: An apparatus and method determines and controls the oil level in one or more refrigeration system compressors. The invention returns lubricating oil to the compressors to maintain oil levels sufficient for proper lubrication of each compressor, and also monitors the flow rate of oil returned to each individual compressor. A level sensor and a flow control device are connected to a control circuit to control the flow of lubricating oil returning to the compressors. The control circuit controls the return flow of oil as well as various other functions of the system, monitors compressor oil levels, and determines the rate oil is returned to each compressor. The method includes measuring system parameters, comparing measured oil levels to desired oil levels, and injecting lubricating oil into a compressor if the measured oil level is below the desired level. The amount of oil added is then calculated and the oil flow rate is measured.

Abstract: An air conditioning system of the present invention has a refrigerant circuit including a compressor, an oil separator, a condenser, a expansion device, an evaporator, a first accumulator, and a second accumulator which are connected in order by piping, said evaporator, said first accumulator, said second accumulator, and said compressor being connected in series; a first oil return bypass for connecting said oil separator and a connection pipe between said first and second accumulators; and a second oil return bypass for connecting said first accumulator and a connection pipe between said second accumulator and said compressor.

Abstract: A normally closed valve is located downstream of the oil separator to insure that sufficient oil pressure builds up to lubricate the compressor. The valve is responsive to the differential pressure between discharge and economizer such that throttling takes place over a limited portion of the operating envelope.

Abstract: Two compressors are connected in tandem for an air conditioning system. A control board that includes a microcontroller controls the operation of the system in response to the energization of first and second stage terminals of a thermostat. The system includes anti-short cycling and eliminating operation of crankcase heaters during a time period following the shutting off of the compressors.

Abstract: In a system having low and high stage compressors with an oil separator downstream of each stage there can be a tendency for oil from the first stage to collect in the second stage. So, responsive to a low level of oil in the first stage oil system, oil is supplied from the second stage oil system to the first stage oil system.

Abstract: A refrigerant device comprising at least one bearing disposed in a housing having a refrigerant flow path. The bearing is contacted with a lubricant charge of a small quantity of lubricant dissolved in liquid refrigerant. At least a portion of the liquid refrigerant proximate the bearing is vaporized to deposit lubricant on the bearing in sufficient quantity to provide for the lubrication thereof. The refrigerant may be vaporized by heat or by pressure drop, or by both. A sensor may be provided to monitor or control temperature and pressure conditions to insure that sufficient refrigerant is vaporized to form a lubricant liquid of at least about 75% lubricant by volume.

Abstract: A compressor lubricant distributing system includes a suction outlet to an auxiliary compressor housing and a lubricant and refrigerant return conduit. The return conduit extends from the suction outlet associated with the auxiliary compressor to a suction inlet conduit leading to a suction inlet of a primary compressor. The suction outlet associated with the auxiliary compressor is positioned at a proper lubricant level in the auxiliary compressor housing. When the primary compressor is operated, the suction created at its suction inlet is applied to the suction outlet associated with the auxiliary compressor, this suction draws excess lubricant at the auxiliary compressor back to the primary compressor.

Abstract: A method of compressor over temperature protection. The method comprises the steps of monitoring the temperature of oil entering a compressor, determining an oil temperature differential between the entering and exiting oil temperatures, comparing the oil temperature differential to first and second predetermined limits, terminating compressor operation if the first limit is exceeded by the oil temperature differential, and terminating compressor operation if the second temperature limit is exceeded by the oil temperature differential for longer than a first time period.

Abstract: A method and apparatus for monitoring oil charge loss for use with a refrigeration system. The refrigeration system has a compressor for compressing a refrigerant gas, an oil/gas separator for separating compressed refrigerant from lubricating oil, a condenser for condensing the compressed refrigerant gas, an oil cooler for cooling oil separated from the refrigerant, the refrigerant and oil both having known and differing coefficients of heat transfer, and an injection system for injecting the cooled oil into the compressor.

Abstract: A method of starting a compressor of an air conditioner involves raising the operation frequency of the compressor from zero to a target operation frequency in different patterns (stages), depending upon (1) whether the air conditioner is being operated in a heating mode or a cooling mode, and (2) whether, during a heating mode, the target operation frequency is in a high range, a medium range, or a low range. During a heating mode at either of the high and medium target frequency ranges, the compressor frequency is increased and decreased on its way to reaching the target operation frequency.

Abstract: A compressor oil management and separation system for refrigeration installations, including a main oil storage tank, a pump, valves and remote control means for selectively directing oil from the tank to any one or more of several compressors. Oil separation units are connected for collecting oil from low pressure refrigerant and delivering such separated oil to the tank for reuse or disposal. Each oil separation unit includes a collection vessel, valves for selectively alternately connecting the vessel with low pressure refrigerant and the tank, and means for increasing pressure within the vessel for forcing oil toward the tank.

Abstract: Loss of oil due to oil feedback is prevented in a screw compressor in a refrigeration application due to low capacity operation. The apparent suction temperature is compared to the temperature of the water exiting the evaporator to determine the apparent superheat and the loading is increased upon the apparent superheat reaching a predetermined level. Upon sensing a predetermined difference, an electronic slide valve block is initiated to prevent further unloading and loading may be initiated in a fixed amount, incrementally or on a pulsed basis.

Abstract: The compressor activation control unit a rotation detecting means for detecting whether or not the motor is normally activated when the compressor is activated, a judging means for judging that the compressor interior is filled with a liquid refrigerant when the motor is not judged to be in the normal activating condition by the rotation detecting means, and a control means for step-driving the motor at a very slow-speed no more then one rotation per second through the driving circuit when the motor interior is judged to have been filled with the liquid refrigerant by the judging means.

Abstract: An air-conditioning apparatus comprises at least one variable-capability compressor which is contained in a casing together with a lubricating oil, and at least one fixed-capability compressor which is also contained in a casing together with a lubricating oil. The capability of the variable-capability compressor and the number of fixed-capability compressors to be driven, are controlled in accordance with the sum of the air-conditioning loads of a plurality of indoor units. The casings are connected together by means of an oil-balancing pipe. The air-conditioning apparatus further comprises a plurality of oil-balancing devices. These oil-balancing devices are driven on the basis of different control patterns and distribute the lubricating oil between the casings by way of the oil-balancing pipe. The oil-balancing devices are selectively driven in accordance with both the control of the capability of the variable-capability compressor and the control of the number of fixed capability compressors to be driven.

Abstract: An air conditioning system (10) for an aircraft, the air conditioning system (10) having a separator (14) located between the high pressure side of a compressor (12) and a condenser (18). A timer (34) activated normally open solenoid (32) is located on a separator drain line 28 to periodically dump the lubricant accumulated in the separator (14) back into the compressor (12).

Abstract: The present invention relates to the cooling and heating dual-purpose air conditioner, and more particularly to the heat pump type cooling and heating dual-purpose air conditioner wherein the stand-by control is performed in order to prevent the viscosity increases caused by the lubricating oil freeze in the compressor occurring at the initial cooling operation stage and therefore the smooth drive of a compressor in an air conditioner is performed by the preventing of the lubricating oil freeze.

Abstract: An oil recovery system for a closed type centrifugal refrigerating machine. The refrigerating machine includes a compressor that has an oil sump below the suction side thereof, a condenser that liquefies compressed refrigerant gas by cooling, an evaporator that evaporates the liquefied refrigerant, a suction volume control valve that controls the volumetric flow of refrigerant gas sucked into the compressor from the evaporator, recovery means for recovering oil from the oil sump to an oil tank in a lubricating system, and control means for starting or stopping the compressor in accordance with the magnitude of refrigeration load. The oil recovery system comprises valve opening control means for controlling the opening of the suction volume control valve such that a decrease in the amount of oil recovered to the oil tank is compensated for when the number of times of start or stop of the compressor per unit of time exceeds a set number.

Abstract: A refrigerator having a refrigerant circulating circuit for circulating a mixture of a refrigerant and a refrigerating machine oil. The refrigerator includes a compressor with a bypass circuit or a variable displacement compressor, a state detecting sensor for sensing the degree of separation of the refrigerant mixture, determining circuit for determining whether the detected degree of separation is in a two phase separation area, and a control unit for controlling the amount of the refrigerant passing through the bypass circuit or the displacement of the variable displacement compressor. When the refrigerant mixture enters into the two phase separation area, the amount of discharge or the displacement of the compressor is decreased. The temperature of refrigerant mixture is lowered accordingly and the phase changes from the two phase separation area. The refrigerating machine oil is maintained in a uniformly mixed state with the refrigerant and circulates with the refrigerant to the compressor.

Abstract: The normal path for the flow of oil/refrigerant being reclaimed from the cooler is changed during periods of low load operation such that the oil/refrigerant mixture flows directly from the cooler to the ejector rather than by way of normal suction housing pass. This is accomplished by valve means responsive to either a pressure differential or the guide vanes position, either of which is indicative of the load condition.

Abstract: A pressurized supply of oil for lubrication and other purposes for a helical screw compressor is automatically and continuously maintained in an oil separator in the compressor discharge line by a check valve assembly which is controlled by the pressure differential between the compressor inlet and the condenser, a bypass around the valve's control element permitting equalization of pressure on its opposite sides to permit closing by a biasing element.

Abstract: An oil level sensor device for sensing and controlling the level of oil in the crankcases of refrigeration compressors, each compressor having a crankcase with a housing for oil that accumulates during the compression operation and each housing having an opening with a prism member mounted in it, the prism members having two angularly relating surfaces exposed to the oil in the crankcase and a light source and a light sensor mounted adjacent to the prism on the outside of the crankcase housing such that the light from each light source impinges on one of the angularly related prism surfaces and is reflected thereby to the second angularly related surface and then back to the light sensor. Each light sensor has an output which is connected to the input of the control circuit which operates to energize a solenoid valve to add oil to the crankcase from a remote source when the oil level in the crankcase as sensed is below a predetermined level.