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(11) | EP 0 677 712 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A stabilized conditioning unit, especially for individual installations |
| (57) The unit comprises: user circuit (3) with circulating pump (5); a refrigerating and/or
conditioning circuit (9) with cooling unit (10), accumulator tank (12) and circulating
pump (14); a connecting loop (20) between the two circuits (3; 9), with two connecting
arms (20A; 20B) between the two circuits and two arms (20C; 20E) belonging to the
two circuits; and a three-way valve (22) on the user circuit and on said loop (20),
to split the fluid flowing in the user circuit with part of the fluid being recycled
directly into the user circuit and part of the fluid being recycled via the loop and
the conditioning circuit; the three-way valve (22) is controlled by the thermostatic
sensor (7). |
[0001] The invention relates to a conditioning (or refrigerating) unit designed so as to be especially sensitive and precise in order to achieve the stability of temperature required by the user unit, at a constant throughput; in addition, the conditioning (or refrigerating) unit of the invention has been designed to be especially compact and require little space in order that individual such units can be made for individual user units so that each user unit is not dependent on a central system that is neither precise, nor constant, nor economical. These and other objects and advantages will be clear from the following text.
[0002] The present conditioning unit comprises a tank for accumulating conditioned (or cooled) liquid, a refrigerating unit with evaporator and condenser, a heating element, circulating means and a sensor for thermostatic stabilization. For these purposes, the said present unit basically comprises:
- a user circuit with circulating pump;
- a conditioning circuit with cooling unit (evaporator or the like), heating element, accumulator tank and circulating pump;
- a connecting loop between the two circuits, with two connecting arms between the two circuits and two arms belonging to the two circuits;
- and a three-way valve on the user circuit and on said loop.
[0003] In this way the fluid flowing in the user circuit is partly fluid recycled directly in the user circuit and partly fluid recycled via said loop and said conditioning circuit; the three-way valve is controlled by the thermostatic sensor on the user circuit.
[0004] The three-way valve may have an outlet towards the pump of the user circuit, a first inlet directly from the user circuit and a second inlet from the connection arm corresponding to the delivery part of the conditioning circuit.
[0005] A single refrigerating unit may also comprise at least one second user circuit with at least one other connecting loop between it and said conditioning circuit.
[0006] The conditioning circuit comprises in practice an accumulator tank, the capacity of which may be very limited, an evaporator and a condenser forming part of a cooling unit of the type using a coolant fluid (such as "freon" or the like), and optionally a heating element. There may also be direct circulation in the conditioning circuit, of the fluid that otherwise flows through the condenser, when the temperature of this fluid is low enough compared with the temperature required by the user unit.
[0007] The invention will be understood more clearly on examining the description and enclosed drawing, the latter showing a practical but nonrestrictive embodiment of the invention. In the drawing:
Fig. 1 shows the overall layout of a conditioning unit according to the invention;
Fig. 2 shows, in isolation, one possible form of a three-way valve applicable to the present layout;
Fig. 3 shows a multiple layout.
[0008] In the form depicted in the accompanying drawing, the numeral 1 denotes a user unit whose temperature must be kept more or less constant and oscillation-free; the throughput of fluid will advantageously be constant. The numeral 3 denotes in a general way a conditioning circuit for the user unit, having a circulating pump 5 and a thermostatic sensor 7 for the user unit. The numeral 9 denotes a conditioning circuit, with a cooling unit 10, a heating element 11, an accumulator tank 12, a circulating pump 14 and a sensor 16 of the conditioning circuit. The cooling unit 10 may be of the type using a circulating coolant with an evaporator 10A, a condenser 10B, a compressor 10C and a circuit 18 connected to the condenser 10B for the removal of the heat from the condenser to an external source; this heat-removing circuit 18 may be shared by a plurality of refrigerating and/or conditioning units of the sort described and also for other refrigerating and/or conditioning systems.
[0009] The numeral 20 denotes a connecting loop between the two circuits 3 and 9; this loop 20 comprises two connecting arms 20A, 20B between the two circuits 3 and 9 and two arms 20C and 20E belonging to the two circuits 3 and 9 respectively. The numeral 22 denotes a three-way valve with actuator 22A; the three-way valve is arranged with one inlet on the arm 20C and its outlet on the circuit 3, while the other inlet of said valve is connected to the connecting arm 20B that corresponds to the delivery of the circulating pump 14 of the conditioning circuit 9. The three-way valve 22 is controlled by the sensor 7 fitted in the user circuit 3. Fig. 2 shows a typical diagram for a three-way valve with an inlet 22B, which can be the one connected to the arm 20B, and an inlet 22C, which can be the one corresponding to the arm 20C, while 22E denotes the outlet connected to the intake of the pump 5 of the user circuit 3.
[0010] The cooling unit 10 can be excluded from the conditioning circuit 9 when the temperature of the fluid flowing through the condenser is low enough compared with the temperature required by the user unit; in these circumstances it is possible directly to include in the conditioning circuit 9 the circuit 18 which carries off the heat from the condenser 10B, by connecting up arms 18A, 18B shown in chain lines in the layout of Fig. 1, and excluding the cooling unit 10. It is possible and preferable - for this purpose - to insert a valve 26 on the arm 18A, 18B of the circuit 18 and a valve 28 on the arm of the circuit 18 that runs through the condenser 10B; a suitable valve 30 can also be used to exclude the evaporator 10A. In this way the consumption of fluid flowing through the circuit 18 is reduced.
[0011] The operation of the conditioning unit described above, when the arm 18A, 18B is excluded and the cooling unit 10 is active, is as follows. Two independent circulations are generated by the pumps 5 and 14 on the two circuits 3 and 9, each of which comprises one arm, 20C and 20E respectively, of the loop 20. By adjusting the three-way valve 22 it is possible to divide the return via arm 20C of the loop 20 from the user circuit 3 and mix the flow drawn in by the pump 5 with a fraction of the liquid flowing in the conditioning circuit 9 and coming from arm 20B of the loop 20; altering the proportions between the two fractions taken in this way from each flow by the three-way valve enables immediate corrections to be made to the cooling or heating power delivered to the user unit 1, with the result that temperature corrections designed to keep the temperature of the user unit 1 stable are immediate. Furthermore the separation of the user circuit 3 from the conditioning circuit 9 makes it possible greatly to reduce the size of the components associated with the conditioning circuit 9, especially that of the accumulator tank 12, owing to the possibility of rapid intervention and to the possibility of allowing thermal hysteresis in the accumulator tank 12, precisely because the presence of the loop 20 and three-way valve 22 enables corrections to be made. It is consequently possible for the present conditioning unit to be much more compact than is usual, to the extent of permitting a single installation for each user unit while keeping the dimensions of this conditioning unit connected to each user unit quite tolerable in practice; this would apply, for instance, to a plastics moulding press in which the user unit is represented by the mould, which must be preheated and then maintained constantly at a very precise temperature with minimal oscillations and fast corrections. Limiting the size and capacity of the accumulator tank 121 makes it possible and useful also to reduce the other components of the cooling unit 10, and in particular the evaporator 10A and condenser 10B.
[0012] It is also possible to produce direct circulation of the heat-removing fluid provided in the condenser 10B by disconnecting the entire cooling unit 10 and directly connecting up to the circuit 18, via the arms 18A and 18B, that part of the conditioning circuit 9 that includes components 12, 14 and 16 when the temperatures of the fluid flowing in the circuit 18 are low enough compared with the temperatures required for the user unit.
[0014] It is not ruled out that (see Fig. 3) a single conditioning circuit 109 similar to circuit 9 can also be used for two user units 101X and 101Y by providing individual loops 120X and 120Y between a common circuit 109 and the respective independent user units 101X and 101Y. The two loops 120X and 120Y may share the arm 120E, and respective user circuits 103X and 103Y with respective pumps 105X and 105Y and respective three-way valves 122X and 122Y. The two loops 120X and 120Y may share the arm 120E or may have respective arms 120 in parallel on the circuit 109.
[0015] A conditioning unit as described makes it possible to construct highly simplified conditioning and refrigerating systems offering a wide range of temperature usage with precision and fast intervention for the thermostatic control of each user unit, to suit what may be the different requirements of the various user units of, for example, a factory, and even with a part that is common to all the conditioning units, in as much as these can all be connected to the same heat-removing circuit such as 18.
[0016] The three-way valve 20 or the three-way valves 122X and 122Y can be located at different nodes of the loops 20 and 120 from their (preferred) locations indicated in the drawing.
[0017] A process conditioner according to the invention is compact and highly precise. It is suitable for a wide range of applications. One example that can be cited is the rubber and plastics processing industry, which is continually expanding. New processing technologies and the continual development of new raw materials are forcing both greater specialization of the different manufacturing processes and also research into the best methods of cooling. This specialization requires the adoption of a conditioning system with the following characteristics, among others: ability to provide different conditioning for each individual process; a wide range of temperatures; the ability to condition the process by both heating and cooling; stability and precision of temperature and of the flow rate of the conditioning water through each individual user unit.
[0018] A conditioning unit according to the invention represents an appropriate technological proposal capable of satisfying all the demands discussed above. Extremely compact and quiet-running, this unit can be positioned next to the process, close to the operator and taking up very little productive space. Owing to the possibility of communication, it is able, by means of a suitable protocol, actually to be controlled and programmed directly by the manufacturing machine and to adjust itself as occasion requires to the demands of the particular type of work.
[0019] Its complete independence from other processes and its extremely precise electronic control guarantee not only that the flow rate of the recycle fluid is kept constant but also that the required temperature is maintained exactly.
[0020] The process conditioning unit according to the invention can have use temperatures ranging between -5° and +90°C and can keep a required constant temperature with a maximum error of ±1°C. The unit can easily be designed to supply a large fluid flow rate to the user unit and can guarantee a temperature gradient across the user unit of less than 2°C. This ensures perfect uniformity of temperature over the entire surface of the part to be conditioned.
[0021] Since it can be water-condensed, the unit in question can be cooled by being connected to a closed-circuit water-air heat-removal system. In this way the heat produced by the various cooling units can be dissipated into the external environment by a single centralized means. This provides two fundamental advantages: improved efficiency during the summer, since the heat-removal means can be set up in a remote position where there is ventilation; and the possibility - in the cold season - of cooling the process by directly using the water from the heat-removal means and switching off the cooling compressors of individual cooling units, thereby saving a considerable amount of energy. A microprocessor control unit can be used to turn the system on and off automatically so that the energy saving in different circumstances is optimized in accordance with the required temperature.
[0022] When compared with conventional systems the use of separate units and centralized heat-removal means provides many advantages, including:
1) VERSATILITY AND FLEXIBILITY, the following being made possible: individualized control of the temperature of the fluid and of the pressure in each individual user unit; wide range of use (-5°C, +95°C) with both cooling and heating being possible; programmability through a serial connection with the manufacturing machine; optimization of the relationship between the process and the temperature of the conditioning water;
2) CONSTANCY AND PRECISION, the following being made possible: precision and stability of temperature with an error of ±1°C; "infinitesimal" graduation of the delivered cooling or heating power from 0 to 100%; constancy of flow rate and pressure at the user units, uninfluenced by the other processes; perfect uniformity of production, fewer rejects, greater productivity;
3) EASY INSTALLATION AND CONTROL, the following being made possible: ease of handling, installing and commissioning without expert assistance; "on-board-machine" location close to the process and to the operator; almost no maintenance necessary; additional system engineering is simple and economical, with no insulating of tubes or air ducts; immediate replacement in the event of breakdown with less damage arising from production stoppages; ability to fill and empty the user circuit completely automatically, without losing any conditioning fluid, thus greatly reducing the time required to change moulds;
4) ENERGY SAVINGS from the following: low start-up currents because of the subdivision of the power; no loss to the environment from the cooled-water distributing pipes; optimization of the cooling system, thanks to the differentiation of temperature for each individual user unit; greater efficiency in summer due to improved dissipation of the heat of condensation through the externally-installed heat-removal means; ability to recover the heat of condensation generated by the refrigerators by producing hot water at temperatures of up to 50°C; improved efficiency under reduced loading due to the centralization of the removal of the heat of condensation;
5) ECOLOGY, inasmuch as the system suggested has in total from 50 to 70% less coolant compared with a conventional air-condensation system of equal power and, furthermore, this coolant is distributed across many small independent circuits, which means that if a leakage did occur, much less gas would be released into the environment.
[0023] It will be understood that the drawing shows only an illustrative embodiment given purely by way of a practical demonstration of the invention, it being possible for the invention to be modified as regards forms and arrangements without thereby departing from the scope of the concept underlying said invention.
- a user circuit (3) with circulating pump (5);
- a conditioning circuit (9) with cooling unit (10), heating element (11), accumulator tank (12) and circulating pump (14);
- a connecting loop (20) between the two circuits (3, 9), with two connecting arms (20A; 20B) between the two circuits (3, 9) and two arms (20C; 20E) belonging to the two circuits;
- and a three-way valve (22) on said loop (20), to split the fluid flowing in the user circuit (3) with part of the fluid being recycled directly into the user circuit and with part of the fluid being recycled via said loop (20) and said conditioning circuit (9); said three-way valve (22) being controlled by the thermostatic sensor (7).