WO2008154920A1

WO2008154920A1 - Refrigerating installation

Info

Publication number: WO2008154920A1
Application number: PCT/DK2008/000220
Authority: WO
Inventors: Hans Kurt Petersen; Kirsten Bladt Nielsen; Allan Juhl Moustgaad
Original assignee: Danfoss A/S
Priority date: 2007-06-19
Filing date: 2008-06-17
Publication date: 2008-12-24
Also published as: DE102007028563A1

Abstract

The invention relates to a refrigerating installation comprising a refrigerant circuit provided with a plurality of evaporator sections and a distributor (5) for distributing refrigerants to the evaporator sections, said distributor (5) comprising a controllable valve (14) for each evaporator section. The aim of the invention is to enable the refrigerating installation to be operated as desired using simple means. To this end, the distributor (5) comprises a rotor embodied as a camshaft (21) and provided with a cam (25) for each valve (14).

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 refrigerants on the evaporator sections distributor, wherein the distributor has a controllable valve for each evaporator section.

Such a cooling system is known for example from DE 19547 744 A1. This cooling system has a single compressor and a single condenser, but two separate evaporators. The supplied by the compressor refrigerant flow is divided after the condenser and before the expansion organs by means of a 3/2-way valve in two sub-streams, the position of the 3/2-way valve is controlled by a regulator unit. With such a design, it is difficult to supply more than two evaporator sections.

US 5,832,744 shows another cooling system, in which the distributor between a refrigerant inlet and a plurality of refrigerant outlets has 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.

Although such a design theoretically ensures a uniform distribution of the refrigerant to the individual evaporator. However, even small differences in dimensions, which may result, for example, during production, cause the refrigerant to be distributed unevenly to the individual evaporators. Moreover, such distributors require that the individual evaporators have basically the same thermal load and also the same flow resistance. have stood. If this is not the case, then the case may occur that an evaporator contains too much refrigerant so that the refrigerant is not completely evaporated before it has passed through the evaporator. Another evaporator, which is connected to the same evaporator, can get too little refrigerant, so that the evaporator can not provide the desired cooling capacity. The Überbzw. Lack of supply to the evaporator can lead to difficulties especially when temperature sensors, which are located at the evaporators or other locations of the cooling system, control an expansion valve. The expansion valve can be vibrated under unfavorable circumstances, which further deteriorates the capacity and the effectiveness of the cooling system.

The invention has for its object to achieve a predetermined operation of the cooling system by simple means.

This object is achieved in a cooling system of the type mentioned above in that the distributor has a camshaft designed as a rotor having a cam for each valve.

If the following is a "cooling system", then this term is to be understood. In particular, it includes cooling systems, freezer systems, air conditioning systems and heat pumps, ie all systems in which a refrigerant is circulated or circulated. The term "refrigeration plant" is used for convenience only. The evaporator sections can be arranged in different evaporators. The invention will be explained for the sake of simplicity in the context of multiple evaporators. However, the invention is also applicable when an evaporator has a plurality of individual or groupwise controllable evaporator sections. If the distributor has a controllable valve for each evaporator, then it can individually control the supply of the evaporators, ie it is then possible to supply to each evaporator the amount of refrigerant which it requires. You do not have to worry about it, 5 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 that requires greater cooling capacity will keep the valve open longer, so it will receive more refrigerant than a steamer that has less cooling capacity. The control of the valves takes place in a simple manner by a rotor which is designed as a camshaft. By rotating this camshaft, the cam associated with a particular valve engages or disengages the valve so that it opens or closes the valve.5 Accordingly, only one rotary motor is required to drive the camshaft. If this rotary motor is designed as a stepper motor, then you can adjust the angular position of the camshaft very accurately. It is also possible to stop the camshaft at predetermined rotational angle positions so that, for example, a valve is opened for a longer period of time. Conversely, the camshaft can also be rotated relatively quickly for a short time, so that the valve of an evaporator section, which in and of itself should not receive any refrigerant, is only opened very briefly. Since an evaporator section is relatively sluggish, a short-term opening of the associated valve practically does not lead to a change in the refrigerating capacity.

Preferably, all cams are arranged in different angular positions. This ensures that only one valve is open in each rotational position of the camshaft. It is then possible to supply each evaporator section individually with refrigerant. Preferably, the manifold has a plurality of valve modules, which are arranged parallel to the axis of the camshaft side by side. You can build the distributor modular. Each valve module then contains a valve or optionally several valves. If a larger number of evaporator sections have to be supplied by the distributor, then you put together a corresponding number of valve modules. Since the individual valve modules are arranged side by side, one has basically little space restrictions.

Preferably, the camshaft has a plurality of camshaft modules. Also, the camshaft can thus be assembled in a modular manner, so that you can adjust the camshaft to the number of valves used.

It is preferred that the camshaft modules are mounted on a support shaft. The carrier shaft can be easily formed as a pipe or rod. The camshaft modules are pushed and then clamped on the support shaft, glued or otherwise secured. This also allows setting the angular positions of the individual cams.

Preferably, the camshaft is axially displaceable and has for at least two valves in each case an actuating element surrounding the camshaft, which acts on the valve when the camshaft is displaced. In some cases it is desired to open several valves or even all valves simultaneously. On the other hand, since one needs the cams for the individual opening of the valves, one uses an additional means with which the valves can be opened. This additional means is formed by an actuating element which surrounds the camshaft, that is, can act on the valve in any rotational angle position of the camshaft. For acting the camshaft is then shifted to a position in which the cams can no longer interact with the valve, but only the actuator.

It is preferred that the actuating element has a cone-shaped actuating surface. The actuating surface thus forms a kind of ramp with which the valve element of the valve is actuated, so that a larger or smaller opening of the valve is possible in dependence on the axial position of the camshaft.

Preferably, the camshaft via a threaded connection, which is arranged coaxially to the axis of rotation of the camshaft, connected to a drive motor which is operable in two directions of rotation, wherein the camshaft cooperates with a backstop, which allows rotation in one direction only and in the opposite direction prevented. With such a design, it is relatively easy to operate the camshaft so that it can be rotated on the one hand, but on the other hand can also be displaced axially. When the drive rotates in a first direction, the camshaft is also rotated. The backstop allows this rotation. If the drive turns in the opposite direction, then the backstop becomes effective. The

Camshaft can not be turned further. In this case, the drive turns one part of the threaded connection out of the other part of the threaded connection. Since the part of the threaded connection connected to the drive is stationary, this causes the part of the threaded connection connected to the camshaft to be displaced axially, thereby displacing the camshaft as well. This results in the axial displacement of the camshaft. When the drive rotates again in the first direction, the threaded engagement of the two parts of the threaded connection returns the camshaft to its axial starting position. Preferably, the distributor has an inlet which opens into an inlet space surrounding the camshaft. Through the inlet space, the refrigerant flowing in through the inlet can be distributed to all the valves so that it can flow out into the distributor whose valve is opened.

Preferably, a camshaft bearing is arranged between the inlet and the inlet space. The camshaft bearing is flowed through by the refrigerant. This has the advantage that you must provide for the storage of the camshaft no opening to the outside.

Preferably, at least one valve has a valve element on which an associated cam acts directly. Thus, when the cam engages the valve member, it actuates the valve member to open. This makes it possible to keep the size small.

It is preferred that the valve element is designed as a plunger which is movable away from the camshaft by the cam. This is a relatively simple education. For example, the plunger may have a cone which abuts a valve seat when the valve is closed.

In an alternative embodiment it can be provided that the valve element is designed as a leaf spring. The leaf spring rests with a closing portion on the valve seat when the valve is closed. Here, the leaf spring has sufficient internal bias to keep the valve closed. The cam of the camshaft then lifts the closing portion of the leaf spring against the inner bias of the leaf spring from the valve seat.

Alternatively or additionally, it may be provided that at least one valve has a valve element, which via a deflection of the assigned cam is actuated. In this case, one is free in the movement control of the valve element, ie you can also operate the valve element pulling to open it.

Preferably, the deflection device is designed as a two-armed lever which is pivotable about an axis and acting with an arm acting on the valve element. The two-armed lever can definitely have a curved shape, so that you can keep the required space even with such a measure.

In this case, it is preferred that the axis is formed by a rod which connects several modules together. The rod thus gets two tasks, namely on the one hand the connection of modules and on the other hand, the pivotal mounting of the two-armed lever.

Preferably, at least one valve has a valve element, which can be lifted by a pressure at the outlet of the valve from the valve seat. This achieves two advantages. On the one hand, an overpressure in an evaporator can escape if it is large enough to lift the valve element from the valve seat. On the other hand, a flow in the reverse direction is also well possible, for example, when the evaporator is used in winter as a condenser to achieve a heating effect, or hot gas is used for defrosting. In addition, this embodiment has the advantage that the pressure difference between the inlet and the outlet acts closing on the valve. Also in this case you can easily create a good tightness.

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

1 is a schematic representation of a cooling system, 2 a distributor from the outside,

3 shows a first embodiment of the distributor in longitudinal section,

4 is an enlarged detail of FIG. 3,

5 shows a section V-V of FIG. 3,

6 shows a second embodiment of a distributor in a perspective view without housing,

7, the camshaft of the embodiment of FIG. 6,

8 shows a cross section through the distributor of FIG. 6,

9 is an exploded view of two modules,

10 is a third distributor without housing in plan view,

11 shows the distributor of FIG. 10 in a perspective view,

12 is a module of the distributor of FIG. 10,

13 shows a fourth embodiment of a distributor in longitudinal section,

Fig. 14, the camshaft of the distributor of FIG. 13 in a perspective view and

15 is a section XV-XV of FIG. 13th

Fig. 1 shows a schematic representation of a cooling system 1, in which a compressor 2, a condenser 3, a collector 4, a distributor 5 and a Evaporator 6 are connected together with a plurality of evaporators arranged in parallel 7a-7d in a circuit. The evaporator assembly 6 may also include a single evaporator having a plurality of evaporator sections to be controlled individually or in groups. It is also possible to provide the evaporator assembly 6 with a plurality of evaporators, at least one of which has a plurality of evaporator sections.

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

At the output of each evaporator 7a-7d, a temperature sensor 8a-8d is 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. The control device 9 can also be integrated in the distributor 5.

FIGS. 2 to 15 show various embodiments of the distributor 5 in a partially schematized representation. 2 shows the cost 5 from the outside. The distributor 5 has a tubular housing 10, on whose one end face an inlet 11 is arranged. Approximately radially to the tubular housing 10 a plurality of outlets 12 are arranged, each of which can be connected to an evaporator section 7a-7d. At the inlet 11 opposite side, a drive 13 is arranged, which is designed as an electric stepper motor. This external design can be used in all embodiments. FIGS. 3 to 5 show a first embodiment of the distributor 5. It can be seen that each outlet 12 is assigned a valve 14. The valve 14 can be seen in an enlarged view in Fig. 4. The valve 14 has a cone-shaped valve element 15 which is loaded by the force of a spring 16 in the direction of a valve seat 17. Without the addition of external forces, the spring 16 brings the valve element 15 into abutment against the valve seat 17. The spring 16 is supported in an insert 18, which is pressed into the outlet 12 and has an opening 19 through which refrigerant flows when the valve 14 is open can.

The refrigerant is supplied through the inlet 11 and then enters an inlet space 20, from which all valves 14 depart.

For actuating the valves 14, a camshaft 21 is provided, which is arranged in the inlet space 20. The refrigerant that enters the inlet space 20 thus surrounds the camshaft 21.

The camshaft 21 is connected to the drive 13 in a rotationally fixed connection. So when a rotor 22 of the drive 13 rotates, the camshaft 21 is rotated. At the opposite end, the camshaft 21 is mounted in a bearing 23 having openings 24 through which refrigerant can pass from the inlet 11 into the inlet space 20.

The camshaft has a cam 25 for each valve 14, wherein the individual cams, as can be seen in particular from FIG. 5, are offset from one another in the circumferential direction. In the illustrated embodiment, which has six outlets 12, the individual cams 25 are therefore arranged so that a cam is arranged in the circumferential direction every 60 °. In the axial direction of the camshaft 21, the cams 25 have a distance corresponding to the axial distance of the valves 14. It is now possible to control each valve 14 individually by the fact that the camshaft 21 is rotated so that the valve associated cam 25 lifts the valve element 15 from the valve seat 17 and thus the valve 14 opens. As long as the valve 14 is opened, refrigerant flows from the inlet 11 to the corresponding outlet 12. All other valves 14 are closed, so that all other outlets 12 are not supplied with refrigerant.

By choosing the times in each of which a valve 14 is opened, different amounts of refrigerant can be fed to the individual evaporator sections 7a-7d.

If an outlet 12 is to receive no refrigerant, there are various possibilities. The direction of rotation of the camshaft 21 can be reversed before the cam 25 assigned to the corresponding valve 14 reaches the valve 14. In this case, the corresponding valve 14 is not opened at all. It is also possible to move the cam 25 over the valve element 15 in such a way that the valve 14 is only opened for a short time and accordingly only very little refrigerant reaches the corresponding outlet. Due to the thermal inertia of the evaporator such a small amount of refrigerant does not play a major role.

The valve element 15 is here moved substantially radially to the camshaft 21. The cam 25 acts here with a radially outwardly directed pressure force on the valve element 15 a.

Figs. 6 to 9 show a second embodiment in which the same and corresponding elements are provided with the same reference numerals. In FIGS. 6, 7 and 9, the housing 10 has been omitted for reasons of clarity. The camshaft 21 has, as in Ausführungsbeispiei of Fig. 3 to 5 also, cam 25, each of which is associated with a valve 14.

In contrast to the exemplary embodiment, which is shown in FIGS. 3 to 5, the cams 25 no longer act directly on the valve element 15, but via a two-armed lever 26, which is pivotable about an axis 27. The cam 25 acts on an arm 28 and pivots it. The other arm 29 of the lever, which is engaged with the valve element 15, 0 is pivoted in the same direction. He pulls the valve member 15 away from the valve seat 17 radially inwards. The camshaft 21 thus acts on the valve element 15 via a deflection device, namely the lever 26. The valve element 15 can also be opened by a pressure in the outlet 12, if this pressure is greater than the pressure in the inlet space 20. This has several advantages , On the one hand, an overpressure in the outlet 12 is prevented. On the other hand, the manifold 5 can also be operated in the reverse flow direction, for example, if you want to defrost the o cooling system with hot gas or if the evaporator is used as a capacitor, for example, to act as a heater in winter. Moreover, in this embodiment, the pressure difference between the inlet space 20 and the outlet 12 is used to additionally hold the valve element 15 in contact with the valve seat 17, so that the sealing is improved.

As can be seen in particular from FIG. 6, the distributor is constructed from a plurality of modules 30. Each module 30 has a ring 31 in which the lever 26 is mounted. The axis 27 serves at the same time to connect several modules 30 together. On the ring 31, a base 32 is arranged for each outlet 12. In the base 32 is then the valve 14th As can be seen in particular in FIG. 7, the camshaft 21 has a carrier shaft 33 on which a plurality of camshaft modules 34 are arranged. Each camshaft module 34 carries a cam 25. Spacers 35 may be arranged between the 5 camshaft modules 34. The camshaft modules 34 are rotationally fixed and axially fixed on the carrier shaft

Held 33, for example, by shrinking, clamping, gluing, welding or the like.

o By using modules 30, 34, the distributor can be adapted to different needs. If more or less outlets 12 are required, more or fewer modules 30 will

34 used. The embodiment shown in FIGS. 3 to 5 can also be realized by a succession of modules which are arranged parallel to the axis of rotation of the camshaft 21 next to each other.

FIGS. 10 to 12 show a third embodiment of a distributor without the housing 10.

The distributor in turn has a number of modules 30. Each module 30 has an outlet opening 36, which is connected in a manner not shown with the outlet 12. The outlet port 36 communicates with a valve seat 37 (FIG. 12) which is closed by a sealing portion 39 of a leaf spring 38. The leaf spring 38 is connected at its end facing away from the sealing portion 39 with the module 30. It has a bias sufficient to hold the sealing portion 39 in contact with the valve seat 37 and thus to close the valve, o when no external forces act. To lift the leaf spring 38 with the sealing portion 39 from the valve seat 37, the camshaft 21 in turn has a cam 25. When the camshaft 21 is rotated, the cam 25 raises the leaf spring 38, so that the sealing portion 39 is released from the valve seat 37.

Also in this embodiment, it is possible that the valve 14 opens when the pressure in the outlet 12 is greater than the pressure in the inlet space 20.

Figs. 13 to 15 show another feature which can be used together with each embodiment of the distributor according to the previous embodiments. Shown is this additional feature in connection with a distributor, as shown in FIGS. 6 to 9.

The camshaft 21 (FIG. 14) has, in addition to the cams 25, an actuating element 40 for each valve 14, which has a cone-like actuating surface 41. The actuating element 40 with the actuating surface 41 is normally located in the axial direction outside a position in which it could interact with the arm 28 of the double-armed lever 26. In this case, the control of the valves takes place exclusively via the cams 25 of the camshaft 21. Accordingly, only one valve 14 is always opened at the same time.

however, in some cases it is desirable to open all valves 14 simultaneously. For this purpose, the camshaft 21 is connected via a threaded connection 42 with the rotor 22 of the drive 13 in connection. When the slider 22 is rotated clockwise, then the two threaded elements of the threaded connection 42 are screwed together. If they have been screwed into one another until the stop, then the rotation of the rotor 22 causes the camshaft 21 is rotated. On its side facing away from the drive 13, the camshaft 21 is provided with a backstop 43, which allows a rotation in one direction, clockwise in the present embodiment, however, prevents rotation in the opposite direction. The backstop 43 is shown in more detail in FIG. It has a spring 44 which presses a latching element 45 radially outward. The latching element 45 has a flat flank 46 and a steep flank 47. In the inside of the housing 10 teeth 48 are provided. When the camshaft 21 rotates clockwise (in the illustration of Figure 15, the direction of rotation is counterclockwise), the flat flank 46 slides over the teeth 48 on the inside of the housing 10 and rotation is possible. If, however, the camshaft 21 rotates in the opposite direction, then hooks the steep edge 47 of the locking element 45 in a tooth 48 and further rotation of the camshaft 21 is not possible.

If the rotor 22 then continues to rotate, then the two parts of the threaded connection 42 are screwed apart. Since the rotor 22 is held with thrust bearings 49, it can not move further in the axial direction. The movement caused by the unscrewing of the two parts of the threaded connection 42 thus acts only on the camshaft 21, which is displaced accordingly and acts with the actuating surface 41 of the actuators 40 on the lever 26 and the valves 14 opens all outlets 12. Depending on the pitch of the threaded connection 42 and the pitch of the actuating surface 41, a very sensitive control of the degree of opening of the valves 14 can be realized.

Claims

claims

5 1. Cooling system with a refrigerant circuit, which has a plurality of evaporator sections and a distributing a distribution of refrigerants on the evaporator sections distributor, wherein the distributor for each evaporator section has a controllable valve, characterized in that the distributor (5) as a Nockenwelle0 (21) trained rotor having a valve for each valve (14)

Cam (25).

2. Cooling system according to claim 1, characterized in that all the cams (25) are arranged in different angular positions.5

3. Cooling system according to claim 1 or 2, characterized in that the distributor (5) has a plurality of valve modules (30) which are arranged parallel to the axis of the camshaft (21) side by side.

0 4. Cooling system according to claim 3, characterized in that the

Camshaft (21) has a plurality of camshaft modules (34).

5. Cooling system according to claim 4, characterized in that the camshaft modules (34) on a support shaft (33) are fastened.5

6. Cooling system according to one of claims 1 to 5, characterized in that the camshaft (21) is axially displaceable and for at least two valves (14) each having a camshaft (21) surrounding the actuating element (40) that with displaced o camshaft (21) opens on the valve.

7. Cooling system according to claim 6, characterized in that the actuating element (40) has a cone-shaped actuating surface (41).

5. 8. Cooling system according to claim 6 or 7, characterized in that the camshaft (21) via a threaded connection (42) which is arranged coaxially to the axis of rotation of the camshaft (21), with a drive motor (13) connected in two Can be operated in directions of rotation, wherein the camshaft (21) with a return lock 0 (43) cooperates, which allows rotation only in one direction and prevents in the opposite direction.

9. Cooling system according to one of claims 1 to 8, characterized in that the distributor 5 has an inlet (11), the NEN in the camshaft (21) surrounding the inlet space (20) opens.

10. A cooling system according to claim 9, characterized in that between the inlet 11 and the inlet space (20), a camshaft bearing (23) is arranged. 0

11. Cooling system according to one of claims 1 to 11, characterized in that at least one valve (14) has a valve element (15) on which an associated cam (25) acts directly. 5

12. A cooling system according to claim 11, characterized in that the valve element (15) is designed as a plunger which is movable by the cam (25) of the camshaft (21) away.

13. Cooling system according to claim 11, characterized in that the valve element o is designed as a leaf spring (38).

14. Cooling system according to one of claims 1 to 13, characterized in that at least one valve (14) has a valve element (15) which is actuated via a deflection of the associated cam (25).

15. Cooling system according to claim 14, characterized in that the deflection device is designed as a two-armed lever (26) which is pivotable about an axis (27) and with an arm (29) pulling on the valve element (15) acts.

16. Cooling system according to claim 15, characterized in that the axis (27) is formed by a rod which connects a plurality of modules (30) with each other.

17. Cooling system according to one of claims 1 to 16, characterized in that at least one valve (14) has a valve element (15, 38) which can be lifted by a pressure at the outlet of the valve (14) from the valve seat (17, 37) ,