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: 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: 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 membrane innerly divides a body in two rooms, one of which is subjected to a first pressure of the ratio of pressures which is to be compared to a threshold. In the other room, there is a gas in pressure equilibrium with its condensate; this gas is in thermal contact with another gas which is also in pressure equilibrium with its condensate and which is subjected to the second pressure of the pressure ratio. The forces on the membrane balance each other when the ratio equals the threshold. The threshold is equal to the ratio between the pressure of the two gases in equilibrium with their condensate. This threshold is substantially stable when the temperature varies. The membrane is connected to control means.

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.