DE1728619A1 - COOLING SYSTEM WITH COMPRESSOR AND RELIEF VALVE - Google Patents

Description

Patent information A η η ρ C Λ Q

Dr. Hugo Wilcken '' ^C ° ^D '*

Dipl.-Ing. Thorms Wiicken Dipl.-Chem. Dr. Woifgan ι Laufer

24 Lübeck, Breita Slralio 52-Ö4 4C Lie j

Az: P 17 28 619.O-15

Applicant: Dunham-Bush Inc., 179 South Street, West Hartford (Connecticut) USA

Cooling system with compressor and relief valve

The invention relates to a refrigeration system in which a compressor is driven by an electric motor and has a relief valve which can be moved into and out of a full load position is to control the compression of the refrigerant and in which an oil feed circulates oil through the compressor.

The object of the invention is to provide the means for maintaining the desired working conditions in compressors for cooling systems under changing loads and extreme application conditions to improve.

This object is achieved according to the invention in that in the cooling system mentioned above, a relief slide valve, which controls an outlet in the compressor house, by the effect of the compressed coolant is forced into its full load position, and that a piston and a cylinder are coupled to this valve are to move it away from its full load position, with the supply connected to supply oil under pressure to the cylinder and to actuate the piston-cylinder arrangement and thereby move the valve out of the full load position.

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The invention and additions to the solution are based on the following the drawing, namely show:

1 shows a schematic representation of an embodiment according to the invention;

Fig. 2 is an enlarged vertical section through

the lower left part of the evaporator cooler, which is shown in the lower part of FIG.

According to the exemplary embodiment in FIG. 1, a cooling system 2 contains a screw compressor 4 with a relief device 5 and a drive by an electric motor 6, an oil separator 8, a coolant outlet pipe 1o, a water-cooled condenser 12, a liquid cooling line 14 leading to a heat exchanger 16 runs, which works as a superheater unit, a dry filter 18 for the liquid coolant, a control arrangement 2o for the liquid supply through which the liquid coolant to a distributor head 22 for a plurality of liquid distribution pipes 24 flows, an evaporative cooler 26 with a coolant inlet head 28 and a plate 3o for a coolant outlet pipe and a return line 32 for the gaseous refrigerant through which it returns to the compressor 4.

The system also includes an oil circulation system with the following in series Parts, namely an oil pump 34, an oil pump 36 driven by an electric motor 37, a Oil cooler 38, through which water flows from a water insert 4o to an outlet 42 and cools the oil coming out of the pump

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exits, and an oil filter 44, an oil feed line 46 supplies Oil under controlled pressure via the distribution lines 48 to the engine bearings 5o and via the lines 52,54 and 56 to the Compressor 4. Oil continues to flow from line 46 via line 58 to unloader 5 and via line 59 to one Load control 6o supplied.

During operation, the dense, high-pressure oil-gas mixture is transferred from the compressor 4 into a chamber passed, and then through the engine, where it flows axially against a baffle plate 64. This gas-oil mixture becomes even dampens and cools the stator and the rotor of the motor, with the motor as the first stage also serving as an oil separator and through Centrifugal action removes the amount of oil contained in the gas. It was found that about 95% of the oil got through the engine is deposited, with the oil at 66 in the lower part of the housing collects, from which it flows through a line 35 to the oil pump 34. The remaining fine oil mist is then through the action of the baffle plate 64 and the oil separator 8 are separated from the gas.

The disc-shaped baffle plate 64 directs the gas flow radially outwards to the outer wall, and the oil then flows axially over the edge of the baffle plate through a passage or channel 68, With an axial alignment to the channel 68 there is an annular separator 70 which effectively removes the oil as it passes out of the gas removed. The separator 7o is a loosely shaped ring,

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made of a woven metal net which is wound on a perforated, tubular mandrel 72. The mandrel 72 forms a central gas outlet channel 74, through which the gas to a gas sampling pipe 73 and then via a shut-off valve 75 to the line 1o flows.

The unit 7o is axially spaced from the baffle 64 to achieve a radial passage 76 through that the gas flows freely radially inward to the channel without passing through the unit 7o. This allows the gas, which axially flows through the channel 68, continue to flow in the axial direction and then flows into the unit 7o and through the Unit 7o therethrough or it can flow radially inward through the channel 76, without restriction in the central one Channel 74. However, there is a tendency that, because of the two-phase liquid flow, the heavier mixture of Gas and oil mist flows along the outer housing wall, while the oil-free gas near the outer edge of the baffle plate 64 flows. As soon as the current flows over the baffle plate 64, the oil-laden gas hits the unit 7o and enters the unit as the lighter oil-free gas makes a sharp turn around the edge of the baffle and flows radially inward through channel 76 to channel 74. The gas and oil mist entering the unit 7o, then move more slowly and that free gas travels radially inward to channel 64.

The oil from the unit 7o adheres to the exposed surfaces

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of the wire mesh and flows downwards, and collects in the lower part of the unit 7o in the oil housing 66. It then flows to the Pump 34 via line 35. During operation there may be a tendency for the oil to flow through some of the channels bridged between adjacent machine parts of the unit 7o. Bridging the channels in this way could cause that the oil is taken up again by the gas, so that this would reduce the performance of the oil separator. In the arrangement according to the invention, however, through which the oil-free gas flows freely through the channel 76, such Recovery does not occur, apparently because of the reduced gas velocity within the unit 7o. Furthermore, the gas is deflected radially around any blocked channels or parts without a back pressure being created. At low loads, there is a tendency that a high percentage of the cooling gas through the unit 7o flows, while at increased loads an increased amount of gas is free of oil and radially inward through the channels 68 flows. The concentric outlet pipe 73 ensures that only oil-free gas flows to line Io.

It has been stated above, _f that the liquid coolant of the evaporative cooler is conveyed 26 through manifold 24 to the inlet header 28th The cool: 26 has cooling tubes 8o which are supported within the housing between its ends and are mounted at their ends in tube plates 82 and 84 (FIG. 2). A perforated plate 86 is mounted on the tube plate 82, which

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behind a head 88 is held in place. The perforated plate 86 has a number of small round openings or bores 9o which lie so that one of them is axially aligned to the end of each of the evaporator tubes 8o.

The head 88 has a number of ribs 92 which against the perforated plate 86, and divide the area of the perforated plate into a number of head chambers, each with liquid coolant take up via one of the manifolds 24. The rib pattern 92 is formed to be substantially the same Number of holes 9o in each head chamber 94 is located. In this way, the coolant which is supplied to each pipe 24 is passed through one of the head chambers and their bores 9o to a special group of evaporator tubes 8o. Every hole 9o works as an expansion unit to create the desired pressure drop so that each evaporator tube actually forms a separate evaporator unit. Substantially the same amount of coolant also flows to each chamber 94 and is then distributed substantially evenly over a relatively small number of evaporator tubes. So is a very effective and reliable arrangement for essentially evenly distributing the coolant: to all Evaporation it reaches rokne.

As discussed above, the Aulaßehden the evaporator tubes are supported in a tube plate 84, and the Tubes open into the housing 96 of the heat exchanger

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Water or some other liquid to be cooled flows to the housing 98 and from there through a couple of lines loo and 1o2. The cooling gas flows through the housing 96 of the heat exchanger 16 and cools the liquid coolant in the coil 1o4, and then the gas flows through a filter 1o6 and through line 32 back to the compressor 4. In the flow path of the return flow Cooling gas there are two control pistons 1o8 and 11o, which the liquid supply or control valves 112 and 114 Check via controls 116 and 118. The valves 112 and 114 are parallel. The valve 114 is at low Loads e.g. closed at loads of 35% of full load and the valve 112 determines the supply of the liquid Coolant to head 22 below 35% full load. At loads above 35% of full load, valve 112 is full is opened and control is exercised through valve 114.

As "mentioned above / the unloader 5 controls the operation of the compressor so that it compresses the amount of refrigerant, which is necessary for the load at any time. Accordingly, the compressor 4 has a slide valve 12o for Capacity control, which is shown in the full load position, in which there is a part of the compressor rotor housing 122 forms. The slide valve 12o is mounted so that it moves from the position shown to the left and thereby exposing an opening in the bottom of the rotor housing through which the suction gas from the central part of the compressor to the suction inlet can flow back. That way the crowd will

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- 8 of the pumped gas decreased.

The slide valve 1 2o is connected by an actuating spindle to a piston 126, which is located in a cylinder 128 is movable. The piston 126 is moved from the position shown by supplying oil to the chamber at controlled pressure 13o moved to the left in the cylinder to the right of the piston. The cylinder 128 is at the left end to the vacuum of the compressor open minded. As soon as oil is supplied to chamber 13o at a pressure which is greater than the outlet pressure, Dapit the piston 126 moves to the left, and when the pressure of the oil in the chamber 13o is less than the outlet pressure, the piston 126 moves to the right. The oil supply line 58 is connected to the chamber 13o via a shut-off valve 132 and a line 134. So if that Valve 132 is open, the oil is immediately supplied to chamber 13o under full pressure in lines 46 and 58. Furthermore, a flow circuit is parallel to the valve 132 through the line 59 and a throttle valve 136 and a shut-off valve 138 provided. Once valve 132 is closed and valve 138 is open, the oil will flow at that pressure the line 46 through the line 59, the throttle 136, the valve 138 and the line 134 to the chamber 13o. The thrush 136, however, limits the amount of flow so that the piston 126 moves a reduced but controlled amount is, while with the valve 132 open, the piston moved at greater speed. This leaves a quick

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Relieve by opening valve 132 or relieve at a lower speed by opening the valve 138 to.

An additional control circuit is provided by a shut-off valve 14o and a throttle 142 in a line 144, which runs between the suction inlet of the compressor housing and the chamber 13o. Thus, when the valve 14o is opened is, the oil in the chamber 13o can freely through the line 134, the throttle 142, the line 144 and the Flow valve 14o to the compressor housing. As mentioned above, once the compressor is in operation, it forces the pressure of the compressed gas on the outlet side of the compressor moves the slide valve 12o to the full load position. Thus, when the valve 14o is open, the pressure on the two sides of the piston is equal because of the flow of oil out of the chamber 13o and the outlet pressure which acts on the slide valve 12o / moves the slide and the Piston 126 back into the position shown. The throttle 142 controls the amount of oil flow out of the chamber 13o and thus controls the amount of movement of the piston from a partial load position to a full load position,

The oil pressure in line 46 is controlled by a control unit 146 which has a valve 148 in a line possesses ,, which runs from the line 46 to the sump 34. A control line 152 runs from the unit 146 to

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Compressor discharge chamber 62 so that unit 146 is responsive to compressor discharge pressure. The unit and their valve 148 work as a check valve to maintain a pressure in line 46 that is around one certain amount above the pressure in the chamber 62 is. The explanation is that when the pressure of the

compressed gas in the chamber 62 loading about 14 kg / cm

carries, the pressure in the line 46 is about 18 kg / cm. Thus, the oil that is sent to the compressor by the various Lines 48,52,54 and 56 delivered through lines 58 and 59 to the unloader on one held a certain value above the compressor outlet pressure. This ensures a suitable and reliable Supply of oil to the engine bearings and the compressor. This also ensures that the unloader will work properly. Opening the valve 132 will stop the compressor, as soon as it is partially or fully stressed, relieve it quickly. Opening valve 14o will shut down the compressor as soon as it is partially or fully relieved to fully debit a taxable amount.

It has been stated above that the heavy mixture of compressed gas and oil mist is a very sufficient one Causes cooling of the motor. The oil mist creates a control effect that improves the heat exchange factor and the cooling of the engine is increased. The oil which is supplied to the compressor can contain a refrigerant and this

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Coolant tries to strengthen and support the cooling effect of the oil. It can thus be seen that the The coolant and the oil circulate in separate circuits, but that the intermediate ratio is maintained, which leads to an improved mode of operation. The pump 36, is set in motion before the engine 6 is started, so that the oil pressure develops and oil for the engine and compressor is generated and the desired oil pressure is provided to the unloader. The controls also call an automatic Relief when starting.

A shunt line 11 for the hot gas is between the outlet line Io of the gaseous coolant and the line 21 of the liquid supply connected so that the liquid coolant from valves 112 and 114 flows to the distributor head 22. The line 11 contains a shut-off valve 23 and a throttle 15. If desired / the valve 23 is opened to put hot gas under control through the throttle 15, and thereby stratification of the liquid phase and unstable operation of the coolant controls to prevent.

The invention contemplates that some of the evaporator tubes 8o. be fed with more coolant than other pipes can. Such arrangements allow changes in the heat transfer or in the cooling effects in different areas. The bores 3o can accordingly be in a chamber 94

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and be of different sizes from one chamber to another. Likewise, different chambers can have different numbers of tubes connected to them, namely with or without changes in bore sizes. There is thus great freedom in terms of structure, while on the other hand reliable and precisely controlled operation is achieved.

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Claims (4)

Dr. Hugo Wilcxen Dipl.-Ing. Thomas Wiicken Dip! - Chem. Dr. Wolfgang Läufer> {^ Lübeck, Breite Strasse 02-54 9 K l |, j -Az: P 17 28 619.Ο-15 Applicant: Dunham-Bush Inc., South Street / West Hartford (Connecticut) USA claims 1. Cooling system / in which a compressor is driven by an electric motor and has a relief valve which is movable into and out of a full load position in order to reduce the compression of the refrigerant and in which an oil feed circulates oil through the compressor / characterized in that a relief slide valve (12o) which controls an outlet in the compressor housing (4) by the action of the compressed Coolant is forced into its full load position, and that a piston and a cylinder (126,128) with this valve are coupled to move it away from its full load position, the oil feed (34,36 etc.) being connected to oil under To supply pressure to the cylinder (128) and to actuate the piston-cylinder arrangement and thereby the valve from the full load position to move out. 2. Cooling system according to claim 1, characterized in that the oil feed (34,36 etc.) to cylinder 128 via a controller is connected, which consists of a first valve (132), which is opened to the relief slide valve (12o) in his S09843 / 0OO5 - ir - to move fully relieved position, and a second valve (14o) consists / which is advantageous in series with a Throttle (142) is and which is opened to allow an oil flow from one end to the other of the cylinder (128). 3. Cooling system according to claim 2, characterized in that a fluid connection between the cylinder and the coolant inlet side of the compressor (4) is provided and that the relief slide valve (12o) the refrigerant discharge pressure of the compressor, and characterized in that the oil flow path (59) is parallel to the first valve (132) and has a third valve (138) and a throttle (136) and either the first valve or the third valve is opened can be to supply oil to move the relief valve to its fully relieved position. 4. Cooling system according to one of claims 1 to 3, characterized by a control unit (146, 148) for controlling the oil pressure, which is supplied to the cylinder, and to maintain the oil pressure at a certain value above the compressor discharge pressure . S09843 / 000S