MXPA99004445A - Process for regulating a refrigerating system, refrigerating system and expansion valve - Google Patents

Abstract

In a process for regulating a refrigerating system (1) using an expansion valve (4), one side of the regulating member is pressed by the pressure of refrigerant at the evaporator side and the other side of the regulating member is pressed by the vapour pressure of a sensor system (22) whose sensor temperature is determined by the refrigerant saturation temperature and by the heat supplied by a heating element (27). Heat supply is regulated depending on a measurement value (overheating or liquid level). Also disclosed is a refrigerating system (1) regulated in this manner and an expansion valve (4) as essential component of such a system. An improved, economic and universally applicable regulation can thus be obtained.

Description

PROCEDURE FOR THE REGULATION OF A REFRIGERATION APPARATUS AND A REFRIGERATION APPARATUS AND VALVE EXPANSION DESCRIPTION DB THE INVENTION: The invention relates to a method for regulating a cooling apparatus, a cooling apparatus and an expansion valve for such a cooling apparatus. From WO 82/04142 a cooling apparatus is known, which has in series a compressor, a condenser, an expansion valve and an evap- tor. It is regulated by means of an expansion valve, which, as an adjusting member, has a membrane or bellows and by the supply of heat by a heating element is influential. One side of the adjustment member is charged by the vapor pressure and a sensor system provided with a liquid-vapor filling, whose temperature of sensitivity is determined by the heat supply. Overheating is measured on the outlet side of the evaporator and the heat supply is regulated depending on the measured value. The heatable sensor is on the outside of the coolant duct of the evaporator, where there is superheated refrigerant vapor. With this, the heat evolution is relatively low and varies with the temperature of overheating- REF .: 30071 From DE 40 05 728 A1 a refrigeration apparatus is known, which is regulated depending on the superheat at the outlet of the evaporator. For this purpose the expansion valve has an adjustment member constructed as a membrane, which is operated on one side by the pressure of the refrigerant at the outlet of the evaporator and on the other side by a pressure corresponding to the temperature of the refrigerant at the outlet of the evaporator. This regulation requires that either the suction duct going to the compressor or a measurement duct constructed for example as a capillary tube reaches the expansion valve. This often leads to a limitation in the operation of the refrigerator. It is presented that a very uneasy regulation is often established with a strong oscillating overheating. In the known case, an additional influence is added to the superheat regulation, which is derived from the temperature in the conduit between the compressor and the condenser. For this purpose, a control medium is filled in one of the two spaces of the membrane casing, which is exchanged heat with the superheated refrigerant at the outlet of the evaporator by means of the membrane and is additionally heated by a heating element. , for example a PTC resistor. US 3 313 121 discloses a cooling apparatus and a method for the same, the regulation of which is carried out, by means of an expansion valve, where it has a diaphragm as an adjustment member, where one side of the membrane is loaded by the membrane. pressure of the refrigerant on the outlet side of the expansion valve and the other side by the pressure of a sensor, which rests on the superheated section of the evaporator. The invention proposes the basic task of improving the regulation of a refrigerator with simpler means and with a good price. This task is solved by the characteristics of claim 1. In this conformation is the sensor in constant thermal contact with the liquid refrigerant, which produces a good heat removal to, essentially, constant temperature. The degree of opening of the valve is generally determined by the supply of heat by means of the heating element, since by means of heating the pressure in the sensor system is increased. As the filling depends on its temperature pressure, it is possible, for example, to use a liquid-vapor filling or an adsorption filling. Here the vapor pressure is a function of temperature and increases with increasing temperature. The larger the load led to the largest heating element will be the degree of valve opening. Due to the following relationship there is practical proportionality: E = KXAX (Tf - Ts) E = the load conducted to the heating element K = heat transfer coefficient A = Heat transfer surface between the sensor and the coolant Tf = Sensor temperature Ts = Coolant saturation temperature The ratio is independent of whether the saturation pressure and the saturation temperature of the refrigerant are straight at the outlet of the valve. The degree of opening of the valve is thus independent of the evaporator pressure. An approximate adjustment with the help of the heating element is not necessary. Since the heat supply is regulated, so by means of a regulator, all the technical possibilities of regulation can be used to improve the regulation, for example using a PI regulator. Other additional functions can also be used on this, such as dependence on the number of revolutions of the compressor, presentation of ice or strong heating of the compressed refrigerant. This allows a very accurate regulation. Another advantage is that the expansion valve closes if the heating element fails. In the following modeling according to claim 2, only the pressure of the refrigerant needs to be captured and in the embodiment according to claim 3 only the temperature of the refrigerant on the outlet side of the expansion valve is captured, a conductive connection between the evaporator outlet and the expansion valve is not necessary. Simple signal lines are sufficient for the connection between the measurement sites and the regulator, and a simple electrical conduit is sufficient for the connection between the regulator and the heating element. This leads to a simple and cheap construction. By adjusting the refrigerating appliance to a specific type of use, the course of driving can be selected more freely than previously possible. The regulation principle is suitable not only for dry evaporator, where overheating is measured, but also for flooded evaporators, in which the liquid level serves as the measuring value. All this allows a multi-faceted application. In the alternative according to claim 4, a small amount of coolant is continuously expanded, also if the expansion valve is closed. Regarding the device, the problem is solved by the characteristics of claim 5 and 6, the two alternatives are given to capture the saturation temperature. If, according to claim 7, the tube is constructed as a capillary tube, this tube can form both the by-pass or jump channel as well as the second angle position. By means of this double function, additional parts can be saved. It is recommended that according to claim 8 the outlet channel be connected to the outlet side of the expansion valve. The expression "exit side" of the expansion valve covers the joint area between the throttle position of the expansion valve and the current evaporator inlet, even if there are switching valves, distributors or special installations. There is thus a great freedom of selection in the placement of the sensor and the equalization channel. It is especially appropriate, however, that these construction parts according to claim 9 are very close to the expansion valve, because then it can be worked with short connecting paths. But it is also essential that the pressure, in the equalization channel, be equal to the pressure at the place where the temperature sensor is placed. If the equalization channel according to claim 10 runs, only a short tube is needed to join the refrigerant conduit to one of the pressure spaces. A still cheaper solution is produced, if the equalizing channel according to claim 11 runs inside the valve. The capillary tube according to claim 12 leads to a clear separation of the temperature of the sensor and the temperature in the pressure space. In the conformation according to claim 13, the coolant conduit connected to the outlet of the expansion valve forms a preferred carrier for the sensor and the heating element. For fixing, a tension band can be used in accordance with claim 14. In the alternative according to claim 15, the sensor is arranged in or next to the box part of the outlet side of the expansion valve, where according to claim 16 the sensor can be formed by a hollow space in the box part . A favorable solution with passage channel is given in claim 17. Here the two alternatives are recommended according to claims 18 and 19. In another preferred embodiment according to claim 20 is the heating element disposed inside the sensor. This produces even better heat transfer and facilitates assembly. The thermal insulation according to claim 21 helps, to avoid failures by heat radiation around it.

An essential constituent part of the refrigerating apparatus, which can also be handled individually, is the expansion valve with the features of claim 22. All the necessary elements are found in the expansion valve or in its immediate vicinity. For practice, according to claim 23, the valve box, the equalization channel and the sensor system form a pre-fabricated building unit, to which the refrigerant pipe can also belong, according to claim 26. connected to the valve outlet. The other conformations according to claims 24, 25 and 27-29 characterize different preferred embodiments. The expansion valve can also advantageously be provided with a passage or jump channel according to claim 31. The invention will be described below with reference to the exemplary embodiments shown in the drawings. Where: Figure 1 shows a connection image of a refrigerating appliance according to the invention with a traveling evaporator for the incoming refrigerant; Figure 2 an expansion valve in a schematic representation; Figure 3 a section along line A-A in Figure 2; Figure 4 a modified expansion valve in a schematic representation; Figure 5 a connection image of a refrigeration apparatus according to the invention with a flooded evaporator; Figure 6 a modified sensor; Figure 7 schematically another alternative of a modified expansion valve; Figure 8 a section in an embodiment of a refrigeration apparatus according to the invention; and Figure 9 another embodiment of an expansion valve. Figure 1 shows a cooling apparatus 1, in which a compressor 2 for the refrigerant, a condenser 3, an expansion valve 4 and a dry evaporator 5 are in series. Under the name dry evaporator is understood an evaporator, in which all the refrigerant to pass evaporates in a single step. The expansion valve 4 can for example have the shape indicated in Figure 2. A valve box 6 has an inlet space 7 and an outlet space 8, between which there is a valve seat 9. The closure piece The corresponding valve is carried by a valve rod 11, which cooperates with an adjusting member 12 in a membrane housing "13. The closure piece 10 is under the influence of a spring 14, whose spring disk 15 by means of an adjusting device 16 is adjustable, furthermore also under the influence of the pressure pK in a lower pressure space 17 and in the opposite direction to the influence of the pressure pT in the upper pressure space 18. With the space 8 on the pressure side The outlet is connected to a coolant duct 19 in the form of a copper tube.Its inner space is connected through an equalizing channel 20 made in the form of a tube with a support 21, which leads to the lower pressure space 17. pK pressure corresponds therefore to the pressure of the refrigerant at the outlet of the expansion valve 4. The pressure space 18 is part of a sensor system 22, whose sensor 23 is connected by a capillary tube 24 to the upper pressure space 18. The sensor 23 remains with a first wall cut 25 next to the coolant conduit 19. A second wall cut 26 on the opposite side serves to support a heating element 27 for electrical energy. A tension device 28, for example a band or arc, serves to fix, the sensor 23 and the heating element 27, in the refrigerant conduit 19. The food stream to the heating element takes place by means of an electric wire. 29. The sensor system 22 contains a liquid-vapor charge, which means that the pressure pT in the pressure space 18 will be equal to the saturation pressure of the charging medium at each temperature of the sensor. As shown in Figure l, it is necessary to drive the expansion valve 4 only a single connection element, properly the electrical conduit 29, which is to be conducted to the area of the expansion valve 4. The thermal load donated by the heating element 27 is communicates by means of a regulator 30, as instantaneous superheat, as the real value, this is the difference between the temperature of the refrigerant and the saturation temperature. To this end, the temperature of the coolant is measured in a known manner with a temperature sensor 31, which is supported on the outlet duct 32 of the evaporator and with a pressure sensor 33, which is connected to the internal space of the duct 32, the refrigerant pressure, which is equivalent to the saturation temperature. The values of the measurement are conducted by signal conductors 34 and 35 to the regulator 30. The sensors 31 and 33 can be electronic sensors, which give electrical signals through the signal conductors. By an entry 36 it is indicated that also other influences can be asserted in addition to overheating. The filling medium in the sensor system is selected in relation to the refrigerant so that in erroneous heating, the sensor pressure pT above the adjustment member is somewhat higher than the pressure of the refrigerant pK below the adjustment member. The pressure ratios are determined in such a way that based on the force exerted from below by the spring 14 this is greater than the force acting from above. With this the expansion valve will close with an accidental heating. But a small heat supply is enough to open the valve. In addition, care is taken that the curve of the sum of the spring force and the pressure of the refrigerant pk in the regulation zone has a constant distance to the curve of the sensor pressure pT. With the help of the spring 14 an overheating is set, for example of 4 ° C. As soon as it is exceeded, the expansion valve is opened. In operation, regulator 30, preferably a PI regulator, is set to a reference value and this is compared with overheating. Depending on the deviation of the measured value from the reference value, the heating load is regulated, so that continuous operation occurs with few oscillations. Here the degree of opening of the valve is proportional to the heat load supplied and precisely independent of the magnitude of the vapor pressure in the refrigerant pipe 19. From figure 2 it is seen that the expansion valve itself is a standard valve , in which however the connections of the two pressure spaces 17 and 18 have been made in a novel way. Because the connections can be made shortly before the expansion valve, the valve housing 6, the equalizing channel 10, the sensor system 22 and the refrigerant pipe 19 can be put as a prefabricated building unit. The electrical conduit 29 and the signal conduits 34 and 35 are allowed to adapt without difficulty in the apparatus that receives the refrigeration apparatus, which also means another cheapening. In Figure 4, figures increased by a hundred are used for the corresponding parts. The difference consists of a hole provided to the equalizing channel 120 internally in the case 106. Furthermore, a hollow space in the valve case 106 serves as the sensor 123, which connects with a wall section 125 in the outlet side space 108. of the valve housing 106, and on the other side it has a wall section 126, which points freely towards the outside and serves for the support of the heating element 127. The sensor 123 and the heating element 127 are covered by an insulation thermal 137, to prevent the outward radiation loss. In this construction a novel valve is provided, which presents all the essential properties and presents a box, which can be prefabricated as a constructive unit with or without the coolant conduit 119.

In the cooling apparatus 201 in Figure 5, identical figures are used for identical parts as in Figure 1 and for the modified parts figures increased by 200. Here a flooded evaporator 205 is used, which by an upper duct 238 and a lower conduit 239 is connected to an accumulation vessel 240. The refrigerant flows as a mixture of liquid and vapor through the conduit 238 to the accumulator vessel 240, while through the lower conduit 239 the refrigerant agent flows to the evaporator 205. This circulation is done by itself, but can be supported by a pump. A charge state indicator 231 reports the liquid level to the regulator 30, which adjusts the opening degree of the expansion valve 4 in such a way that a desired loading height remains. In the sensor 323 shown in FIG. 6, a heating element 327 is disposed in the internal space of the sensor. Such a sensor can be fixed with a tension device similar to the device 28, in the refrigerant conduit 19. It is understood that cooling apparatuses with multiple evaporators connected in parallel can also be operated in the manner described. In this case, the sensor can be arranged before the distributor or in one of the branch pipes after the distributor. The superheat can also be measured in a different way than that shown in Figure 1, for example, by individual temperature sensors before and after the evaporator. It is also possible to coordinate a sensor arranged in the box to the equalization channel in the tubular form of FIG. 1, according to FIG. 5 or vice versa, the internal equalization channel according to FIG. 5 combined with the sensor that rests on the refrigerant conduit according to Figure 1 or Figure 6. Figure 7 schematically depicts an expansion valve 404, whose closure piece together with the valve seat forms a first throttle position 441. A bypass channel or jump 442 bypasses this throttle position 441. It leads from the inlet support 443 of the valve case 406 to the outlet support 444 and presents one behind the other a conduction section, 445 of small cross section, a second throttle position 446 in the form of a small opening and an expansion chamber 447. On the wall of the expansion chamber lies a sensor 423, which is on the opposite side in contact tea The pressure chamber 417 is subjected to the pressure on the outlet side of the refrigerant. In this construction, the refrigerant in the expansion chamber 447 takes the saturation temperature, which also has the refrigerant at the outlet of the expansion valve 404. In the embodiment according to FIG. 8, the corresponding parts are used for the corresponding parts increased by 100 compared to Figure 7. Unlike Figure 7, it bridges the passageway 542 not only the first throttle position 541 of the expansion valve 504, but also the entire evaporator 5, thus the inlet support 543 of the expansion valve 504 to the outlet conduit 532 of the evaporator 5. Again the sensor 523 is left in the wall of the expansion chamber 547 and is heated by a heating element 527. To observe the pressure drop in the evaporator 5, the pressure space 517 is connected by an equalization channel 520 in the form of a capillary tube to the outlet conduit 532. Figure 9 shows another variant form of an expansion valve, wherein the same parts are indicated with figures increased by 600 compared to the representation of Figures l-3. It can first be recognized that the valve 604 of Figure 9 is rotated in relation to the embodiment shown above. In this form of the invention, similar to the shaping according to Figure 4, there is the equalizing channel 620 inside the valve 604. In general it is the valve 604 essentially identical to the shape shown in Figure 2.

In the embodiment of Figure 9, a separate sensor is not provided. Instead, the heating element 627 is placed directly in the case 606 of the valve 604 in the sensor chamber 618. an electrical conduit 629 leads to the regulator 30, as described. In this form of the invention the heat is supplied directly to the sensor chamber 18, by the heating element 627 without the need for a separate sensor and a capillary tube. This makes the valve 604 simpler than in the embodiments shown above. To cause a correct and effective heating of the medium in the sensor chamber 418, the valve 604 must be rotated. The manner of operation according to the invention will now be described more precisely. In each form of the invention, either with the separate sensors 23, 123, 323, 423 or 523 or in the embodiment where the heating element directs the heat directly to the expansion valve 604, the valve is opened without the pressure in the sensor chamber 18 equals the sum of the pressure in the pressure chamber 17 and the force of the spring 14. in the conformation of the invention, which uses a sensor, most of the energy, which is applied by the element heating 27, 127, or 327 will flow in the medium inside the sensor, although a small part will flow through the sensor wall around the medium. The heat of slow heating causes the fluid medium to boil and evaporate. The coolant produces bubbles up to the top of the sensor, where the temperature is lower. The refrigerant vapor condenses giving heat to the upper side of the sensor, which is supported on the outlet side of the expansion valve At the same time the pressure inside the sensor increases, where the pressure in the sensor chamber 18 is applied and the valve opens. Similarly according to the embodiment of the invention according to Figure 7, the heat that is produced by the heating element 627, is applied directly to the medium, which is disposed inside the sensor chamber 618. The heat of the element d The heating means causes the fluid medium in the sensor chamber 618, which increases the pressure inside the sensor chamber 618 and thereby the valve 404 is opened. At the same time, the coolant bubbles rise upwards in the sensor chamber 618 to areas where the temperature is lower. Here it condenses the vapor under the transfer of heat to the liquid surrounding it and the heat is then conducted by the adjusting member 612 to the pressure chamber 417. Therefore, there is a constant heat transfer to the refrigerant, which flows through the valve 604 and in precisely the same way as in the first embodiments of the invention, where there is a constant heat transfer of the sensor 23, 123, 323 to the outlet tube 19, which comes from the evaporation valve

Claims (31)

1. CLAIMS 1. - Procedure for the regulation of a refrigeration device that presents in series a compressor, a condenser, an expansion valve and an evaporator, by means of the expansion valve that presents as a means of adjustment a membrane or bellows, and that by means of the supply of heat from a heating element is influential, where on one side of the adjustment member receives the charge of the portion of the refrigerant that evaporates and on the other side of the adjustment member is the vapor pressure of a sensor system provided with a filling whose pressure depends on the temperature, sensor system whose sensing temperature is determined by the saturation temperature of the refrigerant and by the heat supply, and where the superheat is measured by the outlet side of a dry evaporator or by the level of liquid in a flooded evaporator and the heat supply is regulated by that measured value.
2. 2. Method according to claim 1, characterized in that one side of the refrigerant pressure adjusting member is loaded on the outlet side of the expansion valve.
3. 3. Method according to claim 1 or 2, characterized in that the temperature of the sensor on the outlet side of the expansion valve is influenced by the saturation temperature of the refrigerant.
4. 4. - Method according to claim 1 or 2, characterized in that a part of the coolant next to the throttle position of the expansion valve is driven forward and expanded in a second fixed throttle position, and the sensor behind the second throttle position is influenced by the saturation temperature of the coolant.
5. 5. - Cooling apparatus, which has a compressor, a condenser, an expansion valve and an evaporator arranged in series, where the expansion valve has as an adjustment member that separates two pressure spaces, a membrane or bellows, and is influenced by the supply of heat from a heating element, where one of the pressure spaces is connected by an equalization channel to the refrigerant tank on the evaporator side, where the other pressure space is part of a sensor system provided with a filling, whose pressure depends on the temperature, system whose sensor is in thermal union with the refrigerant on the outlet side of the expansion valve and with the heating element, and where a regulator is provided, which controls the heating element depending on the overheating at the outlet of a dry evaporator, or the level of liquid in a flooded evaporator.
6. 6. - Cooling apparatus that contains in series a compressor, a condenser, an expansion valve, an evaporator -and a jump or diversion channel, which bypasses the throttle position, and there is a second throttle position with a camera connected expansion, where the expansion valve has as an adjustment member separating two pressure spaces a membrane or bellows and which by the supply of heat from a heating element is influential, where one of the pressure spaces is connected by a channel of equalization with the coolant tank on the evaporator side, where the other pressure space is part of a sensor system provided with a filling, whose pressure depends on the temperature, system whose sensor is in heat exchange joint with the refrigerant on the outlet side of the expansion valve and with the heating element, and where a regulator is provided, which controls the eleme The heating factor depends on the overheating at the outlet of a dry evaporator, or on the level of liquid in a flooded evaporator.
7. 7. Cooling device according to claim 5 or 6, characterized in that the tube is constructed as a capillary tube.
8. 8. Cooling apparatus according to claim 6 or 7, characterized in that the equalization channel is connected to the outlet side of the expansion valve.
9. 9. - Cooling apparatus according to one of claims 6 to 8, characterized in that the equalizing channel and / or the sensor are hermetically adjacent to the expansion valve.
10. 10. - Cooling device according to one of claims 6 to 9, characterized in that, the equalization channel is formed by a tube, which connects the internal space of the refrigerant conduit connected to the outlet side of the expansion valve with a support that leads to one of the pressure spaces.
11. 11. - Cooling device according to one of claims 6 to 9, characterized in that the equalization channel runs inside the valve.
12. 12. - Cooling apparatus according to one of claims 6 to 11, characterized in that the sensor is connected by means of a capillary tube to the other pressure space.
13. 13. - Cooling device according to one of claims 6 and 8 to 12, characterized in that the sensor is supported on the cooling duct supported on the outlet of the expansion valve and has contact with the heating element.
14. 14. - Cooling apparatus according to claim 13, characterized in that the sensor and the heating element are stopped by a tension device in the coolant duct.
15. 15. - Cooling device according to one of claims 6 and 8 to 12, characterized in that the sensor is arranged in or next to the box part on the outer side of the expansion valve, and has contact with the heating element.
16. 16. - Heating device according to claim 15, characterized in that the sensor is formed by a hollow space in the box part on the outside.
17. 17. - Cooling device according to one of claims 7 - 12, characterized in that the sensor is placed next to the wall of the expansion chamber.
18. 18. - Apparatus according to one of claims 7, 12, and 17, characterized in that the deflection or jump channel also bypasses the evaporator and the equalization channel is connected behind the evaporator with the refrigerant conduit.
19. 19. - Cooling apparatus according to one of claims 7 to 12, 16 and 17, characterized in that the passageway or opening leads to the outlet side of the expansion valve.
20. 20. - Cooling device according to one of claims 6 to 19, characterized in that the heating element is disposed inside the sensor.
21. 21. - Cooling apparatus according to one of claims 6 to 20, characterized in that the sensor and / or the heating element are covered by a thermal insulation against the surrounding.
22. 22. - Expansion valve for a refrigeration appliance with a valve box, which has a valve seat between a space on the inlet side and a space on the outlet side and between two pressure spaces Fitting member built as a membrane or bellows for the I actuation of the parts of the closure, and with a heating element, where the space on the outlet side and one of the pressure spaces are joined by an equalization channel and where the other pressure space is part of a sensor system provided with a liquid-vapor filling, sensor system, whose sensor is built to exchange heat with the coolant on the outlet side and for heat exchange with the heating element.
23. 23. - Expansion valve according to claim 22, characterized in that the valve housing, the outlet channel and the sensor system form a prefabricated constructed unit.
24. 24. - Expansion valve according to claim 22 or 23, characterized in that the sensor is connected by a capillary tube to the other pressure space.
25. 25. Expansion valve according to one of claims 22 to 24, characterized in that the sensor is arranged in or next to the valve box.
26. 26. - expansion valve according to one of claims 22-24, characterized in that the refrigerant conduit connected to the outlet of the valve is part of the constructive unit and serves as a carrier for the sensor and the heating element.
27. 27. - Expansion valve according to one of claims 22 to 26, characterized in that the heating element is supported on the outside of the sensor.
28. 28. - Expansion valve according to one of claims 22 to 26, characterized in that the heating element is disposed inside the sensor.
29. 29. - Expansion valve according to one of claims 26 to 28, characterized in that, the equalization channel is formed by a tube, which connects the internal space of the refrigerant conduit with a support in the valve box that leads to one of the pressure spaces.
30. 30. - Expansion valve according to one of claims 22, 24 and 27 to 30, characterized in that the equalization channel runs inside the valve housing.
31. 31. Expansion valve according to one of claims 22, 24 and 27-30, characterized in that the inlet and outlet of the expansion valve are connected by a diversion or jump channel, which has a fixed throttle position. with an expansion chamber connected and the sensor rests on the wall of the expansion chamber.