EP1987301A1

EP1987301A1 - Cooling system

Info

Publication number: EP1987301A1
Application number: EP07702485A
Authority: EP
Inventors: Torben Funder-Kristensen; Holger Nicolaisen; Jørgen HOLST; Mogens H. Rasmussen; Jan Holm Nissen
Original assignee: Danfoss AS
Current assignee: Danfoss AS
Priority date: 2006-02-13
Filing date: 2007-02-09
Publication date: 2008-11-05
Anticipated expiration: 2027-02-09
Also published as: US8191384B2; RU2395759C2; JP4896993B2; DE102006006731A1; US20090217687A1; JP2009526192A; US8656732B2; CN101384869A; CN101384869B; US20120198876A1; EP1987301B1; DE502007004320D1; WO2007093175A1; RU2008136475A; ATE473404T1

Abstract

The invention concerns a refrigeration system comprising a refrigerant circuit which comprises several evaporator paths and a distributor (5) which distributes the refrigerant on the evaporator paths. The aim of the invention is to improve the operation of said refrigeration system in a simple manner. According to the invention, the distributor (5) comprises a controllable valve (12) for each evaporation path.

Description

refrigeration Equipment

The invention relates to a cooling system with a refrigerant circuit, which has a plurality of evaporator sections and a distributing a distribution of refrigerant to the evaporator sections distributor.

Such a refrigeration system is known from US 5 832 744. The distributor has between a refrigerant inlet and a plurality of refrigerant outlets a valve, which is followed by a rotating turbine disk. The turbine disk should ensure that the refrigerant is evenly distributed to all outlets of the distributor and thus evenly to all evaporators.

Another distributor that can be used in such a refrigeration system is known from US 6 898 945 B1. Here is located between an inlet and several outlets a valve, with the aid of a pressure drop across the manifold can be adjusted. The valve has a conical pin which is intended to distribute the incoming refrigerant so that it can be distributed among the various circuits through the evaporators.

Although the known distributors theoretically ensure a uniform distribution of the refrigerant to the individual evaporator. However, already cause small differences in dimensions, which may result, for example, in the production that the refrigerant is distributed unevenly to the individual evaporator. Moreover, with such distributors it is necessary that the individual evaporators basically have the same thermal load and also the same flow resistance. If this is not the case, the case may occur that an evaporator receives too much refrigerant, so that the refrigerant is not fully recovered. is constantly evaporated before it has passed through the evaporator. Another evaporator, which is connected to the same manifold, can get too little refrigerant, so that the evaporator can not provide the desired cooling capacity. The over-supply or the undersupply of the evaporator can lead to difficulties especially if temperature sensors, which are arranged at the evaporators or other locations of the cooling system, control an expansion valve. The expansion valve can be vibrated under unfavorable conditions, which further deteriorates the capacity and the effectiveness of the cooling system.

The invention has for its object to improve the operation of the cooling system with simple means.

5 This object is achieved in a cooling system of the type mentioned in that the distributor has a controllable valve for each evaporator section.

If in the following of a "cooling system" is mentioned, then this 0 term is to be understood. It particularly includes cooling systems, freezer systems, air conditioners and heat pumps. The term "refrigeration plant" has been used for convenience only. The evaporator sections can be arranged in different evaporators. The invention will be explained for the sake of simplicity in connection with several evaporators. However, the invention is also applicable if an evaporator has a plurality of individually or in groups controllable evaporator sections.

If the distributor has a controllable valve for each evaporator, then it can control the supply of the evaporators individually, ie it is then possible to supply the amount of refrigerant to each evaporator. feed that he needs. There is no need to worry about the fact that the evaporators all have the same flow resistance. It is also of minor importance if the evaporators have to deliver different cooling capacities. An evaporator in which a larger cooling capacity is required, gets correspondingly more refrigerant than an evaporator, which must provide less cooling capacity.

Preferably, the valves can be controlled by a control device which controls individual valves differently. The control device thus ensures the distribution of the refrigerant to the individual evaporator. However, the control device can also control the valves so that all valves pass through a certain basic flow rate of refrigerant and then, if necessary, a single valve so control that in each case additionally passes the required amount of refrigerant. This is particularly advantageous if the control device controls the valves offset in time from one another. Thus, an evaporator gets only from time to time refrigerant, but in total the required amount of refrigerant. The control device thus controls the duty cycle of the individual valve, ie the ratio of the opening time of the individual valve to a predetermined period length. Within a period length then all valves may have been turned on once. The period length is chosen so that keep the pressure fluctuations in the evaporators within reasonable limits or even virtually unnoticeable. The valves can all be adjusted with a basic opening, so that all evaporators are permanently supplied with refrigerant. The controller then clocks the individual valves in addition, so that each evaporator receives an additional amount of refrigerant depending on demand to cover the refrigerant demand.

Preferably, the control means controls only a single valve so that it has a passage opening which is larger than a Durchlaßöff- tion of the other valves. Normally, when all the valves are closed, the controller will always open only one valve at a time. This facilitates the control and sizing of the refrigerant supplied to a single evaporator. If the individual valves 5 already allow a basic flow rate of refrigerant, only one single valve is ever opened further in order to supply the evaporator connected to this valve individually with the required total amount of refrigerant.

o Preferably, the control device has a rotor, which the

Opening of valves causes. As a result of the rotation of the rotor, the individual valves are opened. This is a very easy way to control the individual valves one after the other.

Preferably, the rotor is driven by a variable speed motor. By changing the speed can then adjust how long the individual valves are open. The fact that the speed is variable, you can keep one valve open longer than another valve. This allows an individual 0 control.

Preferably, the engine is reversible. Due to the reversibility of the motor, it is possible to keep a single valve completely closed for a longer period of time. Before the rotor brings this valve into the open position, the motor is reversed in its direction of rotation, so that this valve remains closed. It is also possible to leave several valves closed when these valves are arranged side by side in the direction of rotation of the rotor.

o Preferably, the rotor is connected to a cam and the

Valves have valve tappets actuatable by the cam plate are. This is a mechanically particularly simple solution to open or close the valves. The plungers are expediently acted upon in the closing direction of the valves by a closing spring. Then, when the cam comes into contact with the plunger, then the valve is opened against the force of the closing spring. The valve closes again as soon as the cam has been rotated further enough.

Preferably, the cam disc has a single cam. This ensures that only one valve can be opened at the same time or opened more than the other valves. Accordingly, it is also possible to individually adjust the opening time of each valve (or the time of the boosted opening), so that this opening time can be largely unaffected by the opening times of the other valves.

It is preferred that the valve tappets have in the direction of rotation a distance from each other which is at least as large as the extent of the cam in the direction of rotation. This makes it possible to let the cam come to rest in a position in which no valve tappet is acted upon. In this case, all valves can remain closed.

Preferably, the valve tappets are arranged parallel to the rotor axis. The term "parallel" is not to be understood here as mathematically exact. It is only important that the valve tappets have a component which is directed parallel to the rotor axis. In this case, the cam, which is arranged on the cam disk, acts parallel to the rotor axis.

Preferably, the cam disc has a displacement drive which acts in a direction parallel to the rotor axis. If the valve tappets are arranged parallel to the rotor axis, it is possible by the displacement of the cam disc in a simple manner, all valves simultaneously open to allow a certain basic flow rate of refrigerant. The cam then each opens a single valve more than the other valves to ensure individual supply of a single evaporator with refrigerant.

5

In an alternative embodiment, it may be provided that the rotor has an axially extending inlet channel communicating with an inlet of the distributor and a radially extending outlet channel, the mouth of which, in rotation with outlet openings communicating with the evaporators, can be brought in overlap. So you use the rotor at the same time as an element of the valve. If the mouth of the outlet channel is in register with an outlet opening, then a flow path from the inlet of the distributor to an outlet associated with a particular evaporator is released. As long as the overlap exists, refrigerant may flow from the manifold inlet to the respective evaporator. When the rotor is further rotated, the refrigerant supply to the evaporator just described is interrupted and the next output in the direction of rotation is supplied with refrigerant. Depending on how long the overlap o stops between the mouth of the exit port and the exit port, a greater or lesser amount of refrigerant may flow into the vaporizer. This overlap time can be changed by adjusting the speed at which the rotor turns.

5 Preferably, the outlet openings in the rotational direction at a distance from each other, which is at least as large as the extension of the mouth of the outlet channel in the rotational direction. In this case, it is possible to stop the rotor in a position in which the mouth of the outlet channel is not in register with an outlet o, so that the refrigerant supply to all the evaporators is broken. You can then use such a position to defrost the evaporator, for example.

It is also advantageous if at the output of each evaporator section, a sensor is arranged, which is connected to the control device. This sensor may be, for example, a temperature sensor. Each evaporator can then be supplied with refrigerant depending on the temperature at its outlet.

In an alternative embodiment it can be provided that the evaporator sections are arranged with a capacitor in series and a sensor is arranged in front of the condenser or the compressor. In this case one does not need several sensors, which determine for example the temperature, but only a single sensor. A single sensor is sufficient if one knows otherwise the operating behavior of the cooling system. With the knowledge of the operating behavior can then decide which evaporator or evaporator section how much coolant to be supplied.

The invention will be described below with reference to preferred embodiments in conjunction with the drawings. Herein show:

1 is a schematic representation of a cooling system with multiple evaporators,

2 is a plan view of a first embodiment of a distributor,

3 shows a section III-III of FIG. 2, Fig. 4 is a sectional view IV-IV of FIG. 5 by a second embodiment of a distributor and

5 is a sectional view V-V of FIG .. 4

Fig. 1 shows a schematic representation of a cooling system 1, in which a compressor 2, a condenser 3, a collector 4, a manifold 5 and an evaporator assembly 6 with a plurality of evaporators arranged in parallel 7a-7d are connected together in a circuit. The evaporator arrangement 6 can also have a single evaporator, which has a plurality of evaporator sections, which are to be controlled individually or in groups.

In a manner known per se, liquid refrigerant evaporates in the evaporators 7a-7d, is compressed by the compressor 2, liquefied in the condenser 3 and collected in the collector 4. The distributor 5 is intended to distribute the liquid refrigerant to the individual evaporators 7a-7d.

At the outlet of each evaporator 7a-7d is a temperature sensor 8a

8d arranged. The temperature sensor 8a-8d detects the temperature of the refrigerant leaving the evaporator 7a-7d. This temperature information is forwarded to a control unit 9, which controls the distributor 5 as a function of the temperature signals of the temperature sensors 8a-8d.

2 and 3 show a first embodiment of a distributor 5. The distributor 5 according to FIG. 2 here has six outputs 10a-10f (for six evaporators) and an input 11. Each output 10a-1 Of is separated from the input 11 by a valve 12. Since the valves are all the same are constructed, the following description is based on valves 12, which are associated with the outputs 10b, 10e.

Each valve 12 has a valve seat 13 which is arranged in a housing block 14. Furthermore, each valve 12 has a valve element 15 which is connected to a valve tappet 16, which protrudes from the housing block 14 on the side opposite the valve seat 13. Both the housing block 14 and the valve element 15 are supported by springs 17, 18 on a cover 19, through which the input 11 is guided and which closes a valve housing 20. The spring 18 is designed as a closing spring which acts on the valve element 15 against the valve seat 13.

In the valve housing 20, a cam plate 21 is rotatably mounted. The cam disc 21 has a single cam 22, which acts on a rotation of the cam disc 21 about a rotation axis 23 each have a valve stem 16, as can be seen by the left valve (in Fig. 3). When the cam 22 acts on the valve stem 16, the valve element 15 lifts off the valve seat 13 and a passage from the inlet 11 to the outlet 10e is released. Once the cam 22 the

Valve stem 16 leaves, the valve element 15 is brought under the action of the spring 18 again to rest against the valve seat 13 and the corresponding valve 12 closes, as can be seen from the output 10 b associated valve 12.

The cam plate 21 is rotated by a motor 24, which is shown here only schematically. The motor 24 is driven by the control unit 9. The motor 24 is operable at a controlled speed. The maximum speed is for example in a size order of 100 U / min. During one revolution, as mentioned, the speed of the motor 24 can be changed. The engine 24 can also be stopped for a short time. Also, the direction of rotation of the motor is changeable.

Thus, the following operation can be realized:

Depending on the signals of the temperature sensors 8a-8d, the individual valves 12 are now each opened so long during one revolution of the cam disc 21 that a sufficient amount of refrigerant can flow through the respective exits 10a-10f, so that the evaporators 7a -7d get enough refrigerant, but not too much refrigerant. If an evaporator requires less refrigerant, then when the cam 22 engages the corresponding plunger 16 of the valve 12, the cam plate 21 will be rotated faster, leaving the valve 12 open only for a shorter time. On the other hand, if an evaporator required a larger amount of refrigerant, the cam disc 21 would rotate more slowly when the cam 22 is in the region of the valve associated with the corresponding outlet.

Since at least one second refrigerant is supplied to each evaporator in a period of about one second, it can be achieved that the pressure in the corresponding evaporator varies only insignificantly, so that a negative effect on the cooling system 1 is not to be feared.

The cam plate 21 is mounted on a rotor 25 of the motor 24. The rotor 25 can now be displaced by an axial drive 26 in a direction parallel to the axis of rotation 23. For example, if it is displaced downwardly (based on the illustration of FIG. 3), then all the valves 12 are slightly opened, so that refrigerant can flow permanently through all the outlets 10a-1 Of. This ensures a certain basic supply of all evaporators. The exact setting The amount of refrigerant which is then supplied to the individual evaporator, as before, by the cam 22 of the cam disc 21st

The individual valves 12 have in the circumferential or rotational direction of the cam disc 21 a distance which is at least as large as the extent of the cam 22 in the circumferential direction. Accordingly, it is possible to stop the cam plate 21 in a position in which no valve has been opened. Such a position is taken, for example, when the refrigerant supply to any evaporator is not required.

With the distributor 5 it is also possible to defrost individual evaporators. In this case, one would reverse the direction of rotation of the cam plate 21 before the cam 22 reaches the valve 12 associated with this evaporator. This valve 12 is therefore not opened. You can keep this valve 12 closed until the evaporator is defrosted. The remaining valves 12 are individually controlled by the cam 22 in the manner described above.

FIGS. 4 and 5 show a modified embodiment of a distributor

5, are provided with the same and functionally identical elements with the same reference numerals.

The distributor 5 of FIGS. 4 and 5 also has a rotor 25. The rotor 25 has an inlet channel 27 constantly in register with the inlet 11 in the valve housing 20, i. regardless of the rotational position of the rotor 25th

The rotor 25 also has an output channel 28 which is directed substantially radially. The outlet channel 28 has an orifice 29, which, upon rotation of the rotor 25, is provided with outlet openings 30a-30f in overflow. come cover. The outlet ports 30a-30f, in turn, are connected to the ports 10a-10f through which communication with evaporators of the evaporator assembly 6 can be made.

Again, the distance between the outlet openings 30a-30f is at least as large as the extent of the mouth 29 of the outlet channel 28 in the circumferential direction. In the position of the rotor 25 shown in Fig. 4, therefore, the output port 28 is closed, so that no refrigerant can be distributed.

Incidentally, the operation of the distributor 5 is similar to the embodiment of the distributor 5 shown in FIGS. 2 and 3.

The rotor 25 is controlled under the control of the control unit 9, under circumstances changing rotational speeds, so that there is always a connection between the input 11 and one of the output ports 30 for a certain time. During this time, refrigerant can flow from the inlet 11 into the corresponding outlet opening 30a-30f and from there to the connected evaporator, which accordingly receives a predetermined amount of refrigerant. When the rotor 25 rotates slowly while the mouth 29 passes over the corresponding exit port 30a-30f, the connection is opened for a relatively long time. If, however, the rotor 25 rotates faster in this situation, then a correspondingly shorter opening time is available. With a longer opening time, more refrigerant can flow into the corresponding evaporator than with a shorter opening time.

By reversing the direction of rotation of the rotor 25, a predetermined output opening 30a-30f can also be excluded from the connection with the input 11, so that a signal to this output opening 30a is provided. 3Of connected evaporator receives no refrigerant at all for a certain time. During this time, this evaporator can defrost.

The fact that now the distributor 5 no longer only takes over the function of a distribution, but for each evaporator includes a separate valve 12, you can do without an expansion valve.

The lines leading to the individual evaporators no longer need to be the same length, because the admission of the individual evaporators with refrigerant is controlled by the valves 12.

In a manner not shown can be arranged in addition to or instead of the sensors 8a-8d a single sensor in front of the condenser 3 or before the compressor 2. Although this sensor is then no longer able to evaluate the desired information for each evaporator or each evaporator section individually. However, if one otherwise knows the operating behavior of the cooling system, for example the different flow resistances, then one can obtain the necessary information even when using only one individual sensor in order to decide which evaporator section 7a-7d should receive how much refrigerant.

Claims

claims

5 having a refrigerant circuit (1) having a refrigerant circuit having a plurality of evaporator sections (7a-7d) and a distribution of refrigerant on the evaporator sections (7a-7d) causing distributor (5), characterized in that the distributor (5) for each evaporator section (7a-7d) has a controllable valve (12; 28, 30a-30f) 0.

2. Cooling system according to claim 1, characterized in that the valves (12; 28, 30a-30f) by a control device (9, 24) are controllable, the individual valves (12; 28, 30a-30f) different- 5 lent drives ,

3. Cooling system according to claim 2, characterized in that the control device (9, 24) only a single valve (12; 28, 30a-30f) controls so that it has a passage opening which is greater than o a passage opening of the other valves ,

4. Cooling system according to claim 2 or 3, characterized in that the control device (9, 24) has a rotor (25) which causes the opening of valves (12; 28, 30a-30f). 5

5. Cooling system according to claim 4, characterized in that the rotor (25) by a motor (24) is driven at a variable speed.

0 6. Cooling system according to claim 5, characterized in that the

Motor (24) is reversible.

7. Cooling system according to one of claims 4 to 6, characterized in that the rotor (25) is connected to a cam disc (21) and the valves (12) valve tappets (16) which through

5, the cam disc (21) are actuated.

8. Cooling system according to claim 7, characterized in that the cam disc (21) has a single cam (22).

0 9. A cooling system according to claim 8, characterized in that the valve stem (16) in the rotational direction at a distance from each other, which is at least as large as the extension of the cam (22) in the rotational direction.

5 10. Cooling system according to one of claims 7 to 9, characterized in that the valve tappet (16) are arranged parallel to the rotor axis (23).

11. Cooling system according to claim 10, characterized in that the o cam disc (21) has a displacement drive (26) which acts in a direction parallel to the rotor axis (23).

12. Cooling system according to one of claims 4 to 6, characterized in that the rotor (25) has an axially extending input channel 5 (27) which communicates with an input (1 1) of the distributor (5), and a radially extending outlet channel (28), the mouth (29) in a rotation with outlet openings (30a-30f), which are in communication with the evaporators, can be brought into overlap. 0

13. A cooling system according to claim 12, characterized in that the outlet openings (30a-30f) in the rotational direction at a distance from each other which is at least as large as the extension of the mouth (29) of the outlet channel (28) in the rotational direction.

14. Cooling system according to one of claims 2 to 13, characterized in that at the output of each evaporator section (7a-7d), a sensor (8a-8d) is arranged, which is connected to the control device (9, 24).

15. Cooling system according to one of claims 2 to 13, characterized in that the evaporator sections (7a-7d) with a capacitor (3) are arranged in series and a sensor before the capacitor (3) or the compressor (2) is.