Abstract: Process and system to produce nearly oil free ammonia using a rotary compressor with liquid injection from a separator tank where the liquid in the tank includes oil and liquid ammonia. The level of oil in the compressed ammonia leaving the separator is much lower than in conventional separators with coalescing elements, because the temperature is lower and there is less oil departure in oil vapor form.

Abstract: Process and system to produce nearly oil free ammonia using a rotary compressor with liquid injection from a separator tank where the liquid in the tank includes oil and liquid ammonia. The level of oil in the compressed ammonia leaving the separator is much lower than in conventional separators with coalescing elements, because the temperature is lower and there is less oil departure in oil vapor form.

Abstract: A single screw compressor includes two gaterotors with associated capacity controller, at the start of the compressor one capacity controller is in a fully unloaded position, and the other capacity controller includes a slide, a thrust mechanism for moving the slide, and an elastic mechanism for holding the slide in a position of part load when the compressor is stopped, the elastic mechanism being deformed during start to let the slide reach a full load position as soon as the discharge pressure of the compressor reaches a set value.

Abstract: A rotary compressor of the type provided with a screw (1) and pinion gear (4) is protected from liquid lock effects by disc spring (17) which applies on the pinion gear shaft (11) a pressure higher than the maximum thrust applied on the pinion gear during normal compressor operation.

Abstract: The expansion valve 103 of the refrigerating machine is controlled by the difference between the pressure in a bulb 104 containing a fixed amount of fluid and the pressure in the evaporator 2. The bulb is mounted in the discharge pipe 1 of the evaporator and is heated by a resistor. In the absence of droplets of liquid refrigerant in the flow through the discharge pipe, i.e when the refrigerant flow rate tends to become too low with respect to the cold demand, the resistor heats up the fluid in the bulb, the pressure in the bulb increases and moves the expansion valve to a more opened position. As soon as droplets hit the bulb in the discharge pipe, said droplets cool down the bulb despite the heating effect of the resistor and the expansion valve is moved to a more closed position. Thus, the flow rate control uses variations in heat transfer coefficients in the discharge pipe rather than superheat temperature in the discharge pipe.

Abstract: A machine for the compression or expansion of a fluid comprising a multi-thread screw having opposite low and high pressure ends, the screw being mountable for rotation about an axis to cooperate in substantially fluid-tight manner in a cylindrical bore of a stationary casing, at least one pinion having teeth disposed for meshing engagement with the screw threads and rotatable about an axis transverse with respect to the axis of screw rotation. The screw is carried by a shaft supported by two sets of bearings respectively disposed on each end of the screw. The casing bore is open at both ends and the high pressure end of the casing includes a hoop having an internal bore diameter substantially smaller than the diameter of the bore. The low pressure end of the casing bore is of a diameter at least equal to the diameter of the screw for introduction of the screw into the casing bore during assembly of the screw and casing.

Abstract: Method and device for grooving an hourglass screw wherein a tool shaft having an axis transverse to the screw blank has a tool movable selectively stepwise relative to the shaft when the tool is not engaged with the screw blank and locking means fix the tool when engaged with the screw blank for the grooving operation.

Abstract: The positive displacement rotary machine to compress or expand a fluid between a high and a low pressure comprises a screw provided with at least one groove, rotatably mounted in a casing and meshingly cooperating with at least one gaterotor carrying teeth which protrude into the groove to define with the casing a volume for variation of pressure of the fluid. One side of the teeth is being exposed to the high pressure fluid. The high pressure side of the teeth is in sealing proximity with a lip of the casing. The center of the gaterotor is hollow and carries bearings supporting the gaterotor for rotation around a fixed shaft extending through the rotor. Said shaft is secured to the casing in a portion thereof facing the high pressure side of the teeth by a key which has an axis substantially perpendicular to the shaft axis and is pressed against a flat portion provided on the shaft.

Abstract: In order to produce oil-free compressed air with a rotary compressor while avoiding the costs involved by a liquid-free compressor, a rotary compressor, especially a single screw rotary compressor is injected with water in which borate, preferably potassium borate is dissolved. This prevents corrosion at no additional cost while improving the bacterial purity of the air produced.

Abstract: Liquid coming from the condenser or present in the fluid discharged by the compressor circulates in grooves provided between a stator 7 and a housing 10 of the motor at a distance from the coils (8, 9) thereof. The liquid cools the stator without any risk of short-circuit in the coils. The liquid may be urged by a centrifugal economizer separator 13 through the liquid outlet 16 thereof, towards liquid inlets 27 and 27'. The pressurized gas produced by separator 13 is sent in the motor housing through slit 17 and then, having cooled the coils, reaches economizer hole 12 of the compressor, through conduit 11. Thus, the heated gas is not sent to the intake of the compressor where it would reduce the compressor capacity and efficiency.

Abstract: A screw (1) rotates inside a bore (2a) of a casing and meshes with teeth (6) of a pinion or gate-rotor (7) comprised of a sealing portion (8) supported by a support portion (9). The sealing portion (8) has a limited angular play with respect to the support portion (9). This allows the sealing portion to undergo brief but abrupt accelerations or decelerations independently of the support portion (9). In order to allow frictionless angular displacement between the two portions liquid is injected between them at a moderate pressure when each tooth is out of engagement with the screw.

Abstract: In a positive displacement machine, a rotor has screw grooves in which pressure chambers are variably limited, at one end, by teeth of a plastic pinion which is the front element of a composite pinion meshing with the grooves. A metal backing pinion supports the plastic pinion. The metal pinion and plastic pinion are rotatable with respect to each other about the axis of rotation of the composite pinion, in conjunction with a deformation of a resilient angular coupling provided between them. This coupling is a metal blade at least partly surrounding the backing pinion shaft between the plastic pinion and the backing pinion, in a groove of the backing pinion. One end of the blade is secured to the plastic pinion, the other end of the blade is secured to the backing pinion. Several embodiments of the blade are disclosed.

Abstract: Liquid from the condenser 34 l is supplied to the innerspace of the motor through pipe 11 and flashes therein while cooling the motor. The resulting gas is sent through pipe 10 to an economizer hole 9 of the compressor. At full load, hole 9 is at a higher pressure than the intake of the compressor. At part load, hole 9 is at a pressure close to the intake pressure. A piston 12 is subjected on one face to the economizer hole pressure and on the other face to the intake pressure. When both pressures tend to be equal, piston 12 travels to shoulder 16 and establishes therewith a pressure drop elevating the pressure in motor housing 7, thereby to maintain in motor housing 7 a pressure able to urge liquid from the motor casing to the evaporator 37 through pipe 38.

Abstract: In a positive displacement compressor, first and second liquid injection holes are provided. The first hole is subjected substantially to the intake pressure. The other is subjected to a higher average pressure. A valve controls flow towards the first hole. When the discharge pressure is high, injection occurs through the second hole, the valve is closed. Under such operating conditions, the compressor has a good efficiency because the gas resulting from flashing of the injected liquid in the compressor needs only to be recompressed from said higher average pressure instead from said intake pressure, and does not take up space in the compressor which would limit the intake capacity of the compressor.

Abstract: In a refrigeration system, a centrifugal economizer discharges liquid towards an evaporator through a wholly static restriction (17), the dimension of which is chosen so as to allow no gas or little gas to escape with the liquid at the conditions of maximum pressure ratio in permanent operation. When the pressure ratio is lower, the flow rate allowed by the restriction tends to decrease with respect to the flow rate delivered by the compressor. This entails an increase in the radial thickness of the liquid ring in the centrifugal device. This in turn increases the pressure upstream of the restriction, whereby compensating the initial tendency of the flow rate to decrease through the restriction.

Abstract: In a refrigerating machine, a reservoir heated by an electric motor driving a compressor contains oil up to certain level. The reservoir is fed with refrigerating liquid complemented with oil. The liquid vaporizes while oil falls down in the liquid state. A number of lubrification conduits connect individual bearings of the compressor with the reservoir above the oil level on the one hand and with the reservoir below the oil level through a micro-orifice on the other hand, so as to send to the bearings refrigerating gas loaded with an oil mist. The bearings are in fluid communication with the intake of the compressor.

Abstract: In a screw volumetric machine, a slide is slidable in a groove along a bore accommodating the screw. This slide is movable to vary the delivery and/or compression ratio. One end of the groove communicates with the low pressure. The other end of the groove communicates with the high pressure. A separation wall separates the two pressures behind the slide. The slide is leak-tightly urged against a free end of the separation wall by holding means which slidingly retain the slide in the groove.

Abstract: A compressor comprises an hour-glass screw meshing with a pinion-wheel and a slide operable to obstruct partly a discharge port so as to increase the compression ratio by delaying the discharge moment. An edge of a part of the slide is used to obstruct the discharge cavity. The other edge of this part is provided with a removable spacer hvaing a thickness adapted to fill the slide-groove for a given adjustment of the slide. If the slide is moved so as to vary the compression ratio, a spacer having another thickness may be mounted to avoid modifying the volumetric capacity.

Abstract: A screw compressor discharges a fluid including a mixture of highly compressed gas and liquid into a separator reservoir, and a hydraulic motor is driven by at least a portion of the fluid. An injection conduit connects the bottom of the reservoir to a liquid injection port through the casing of the compressor. A pump driven by the hydraulic motor is mounted on the injection conduit. The motor-pump assembly is in a common casing. The injection port is in an area of the casing which is substantially subjected to high pressure.

Abstract: Refrigerant liquid containing a little oil dissolved is vaporized while cooling the motor and a portion of the vaporization products is sent into the bearings to be lubricated.The large excess of available heat permits dispensing with an oil recirculating pump and keeping in the motor casing, acting as a sump, the major part of the oil present.