EP4616127A1

EP4616127A1 - Expansion float valve arrangement

Info

Publication number: EP4616127A1
Application number: EP23798792.0A
Authority: EP
Inventors: Johan Van Beek; Niels P. VESTERGAARD
Original assignee: Danfoss AS
Current assignee: Danfoss AS
Priority date: 2022-11-08
Filing date: 2023-11-01
Publication date: 2025-09-17
Also published as: CN120092161A; WO2024099845A1

Abstract

A float valve arrangement (13) is described, the float valve arrangement (13) com- prising a housing (14,15), a first liquid port (8), a second liquid port (9), a balance gas inlet (6), and a balance liquid inlet (7), wherein the balance gas inlet (6) and the balance liquid inlet (7) are connected to a float chamber (5) in which a float (4) is arranged, the float (4) acting on a valve (3) outside the float chamber (4), the valve (3) being arranged between the first liquid port (8) and the second liquid port (9). The valve (3) comprises a cylindrical inner valve element (20) comprising a hollow (23) and a cylindrical outer valve element (21) rotatable around the inner valve element (20), wherein the float (4) acts on the outer valve element (21) and the first liquid port (8) is connected to the hollow (23) of the inner valve element (20). Such a float valve arrangement should handle high pressure differences with little effort. To this end, the valve (3) is arranged within an expansion chamber (26).

Description

EXPANSION FLOAT VALVE ARRANGEMENT

The present invention relates to a float valve arrangement comprising a housing, a first liquid port, a second liquid port, a balance gas inlet, and a balance liquid inlet, wherein the balance gas inlet and the balance liquid inlet are connected to a float chamber in which a float is arranged, the float acting on a valve outside the float chamber, the valve being arranged between the first liquid port and the second liquid port.

Such a float valve arrangement is used, for example, as expansion valve in cooling or refrigeration plants using CO2 as heat carrying medium. CO2 has a high absolute pressure and also requires high differential pressure. However, the float valve arrangement can also be used with other refrigerants.

The expansion valve is used to adjust the level of the refrigerant in an evaporator. To this end, the gas side of the evaporator is connected to the balance gas inlet and the liquid side of the evaporator is connected to the balance liquid inlet of the float chamber. Thus, the liquid level in the float chamber is at the same height in direction of gravity as the liquid level in the evaporator. The float valve arrangement is used to adjust the liquid level in the evaporator. When the liquid level in the evaporator decreases, the liquid level in the float chamber decreases in the same way and the float goes down and opens the valve, so that refrigerant from the first liquid port can flow to the second liquid port which is connected to the evaporator. This process continues until the liquid level in the evaporator has reached its set level. At this point the float closes the valve.

The same is true when the float valve arrangement is used with a CO2 separator which is operated on the high pressures. The high pressures used in connection with CO2 causes some problems with respect to leakages and wear.

The object underlying the invention is to provide a float valve arrangement which can handle large pressure differences with little effort.

This object is solved with a float valve arrangement in that the valve comprises a cylindrical inner valve element having a hollow and a cylindrical outer valve element rotatable around the inner valve element, wherein the float acts on the outer valve element and the first liquid port is connected to the hollow of the inner valve element.

When the first liquid port is supplied with refrigerant under high pressure, this pressure is limited to the hollow of the inner valve element. The inner valve element and the outer valve element together form throttling means through which the refrigerant has to flow to reach the second liquid port. Thus, outside the combination of inner valve element and outer valve element there is a lower pressure which is easier to handle than the higher pressure at the first liquid port and chambers or spaces which are directly connected to the high pressure port. Thus, the risk of leakages is kept low. A combination of a cylindrical inner valve element and a cylindrical outer valve element leads to the effect that the opening degree is determined by an angle of rotation between the two cylindrical valve elements. Thus, the float drives the cylindrical outer valve element in a rotational direction around the cylindrical inner valve element.

In an embodiment of the invention the inner valve element comprises a first cylinder wall having a plurality of first openings and the outer valve element comprises at least a corresponding number of wall sections, wherein in a closed position of the valve element the first openings are covered by the wall sections of the outer valve element. When the outer valve element is rotated about the inner valve element, the wall sections of the outer valve element open or close the openings in the first cylinder wall of the inner valve element. Thus, the movement of the outer valve element is directed perpendicular to the direction of the pressure and the forces needed to adjust the opening degree of the valves can be kept low and are basically pressure independent.

In an embodiment of the invention the number of first openings is two or an integer multiple of two. Thus, the number of first openings is an even number. This is a simple way to balance the forces on the outer valve element. The outer valve element can be kept concentrically with the inner valve element.

In an embodiment of the invention the first liquid port is connected to the hollow at a first front face of the inner valve element. Thus, high pressure refrigerant can be fed directly into the hollow without loading other parts of the float valve arrangement with high pressure.

In an embodiment of the invention the hollow is closed at an end opposite to the first front face. Thus, the hollow forms a kind of blind bore so that the high pressure refrigerant is kept within the hollow. No sealings for a rotational part are necessary.

In an embodiment of the invention the float is connected to the outer valve element on a side opposite to the first front face. Thus, this connection can be decoupled from the pressure at the first pressure port.

In an embodiment of the invention the float is connected to the outer valve element by means of a lever which is pivotable around a longitudinal axis of the outer valve element. This is a simple way to translate the movement of the float which is basically a linear movement in the direction of gravity, to the outer valve element. In an embodiment of the invention the valve is arranged within an expansion chamber. In this expansion chamber the refrigerant passing the valve can expand so that the refrigerant can exit the float valve arrangement via the second liquid port with pressure which is lower than at the first liquid port.

In an embodiment of the invention the expansion chamber is arranged in an insert which is mounted in a bore of the housing. Thus, the insert separates the pressure of the refrigerant from the housing, so that sealing problems in the housing can be kept low.

In an embodiment of the invention the insert comprises sealing means with which it is sealed in the bore. These sealing means are provided for separating the refrigerant in the expansion chamber from the interior of the housing.

In an embodiment of the invention the sealing means comprise a first sealing ring at or near a first end of the insert and/or a second sealing ring at or near a second end of the insert. Thus, the insert is sealed at least at one end in relation to the housing.

In an embodiment of the invention the housing comprises a first part and a second part fixed to a mounting face of the first part, wherein the bore comprises a bottom wall opposite the mounting face and the second liquid port is arranged in the bottom wall. In this case the bore is in form of a blind bore, i.e. it is closed at the side opposite the mounting face, wherein only the second liquid port is arranged in this bottom wall. This means that the insert can be mounted in the bore from the mounting face. When the second part is fixed to the first part, the insert is reliably held within the bore. In an embodiment of the invention the valve is configured such that in a fully open position (in a fully open state) of the valve, all first openings are uncovered by the wall sections (not covered by the wall sections) for allowing liquid flow through the first openings, for example from the hollow to the expansion chamber.

In an embodiment of the invention the valve is an expansion valve.

A preferred embodiment of the invention will now be described with reference to the drawing, wherein:

Fig. 1 shows schematically a system in which the float valve arrangement can be used,

Fig. 2 shows schematically a section through the float valve arrangement,

Fig. 3 shows schematically a section perpendicular to the section of Fig. 2 and

Fig. 4 shows details of the valve within an insert.

Fig. 1 shows schematically a system 1 comprising an evaporator 2 (which can also be a liquid separator for a CO2 plant) and an expansion valve 3 which is simply termed "valve" in the following. The valve 3 is actuated by means of a float 4 which is arranged in a float chamber 5.

The float chamber 5 is connected to the evaporator 2 by means of a gas balancing pipe 6 connecting a gas side of the evaporator 2 with a gas side of the float chamber 5 and by means of a liquid balancing pipe 7 connecting the liquid side of the evaporator 2 to the liquid side of the float chamber 5. The valve 3 is arranged between a first liquid port 8 and a second liquid port 9 in the system 1 shown in Fig. 1. The first liquid port 8 is supplied with a liquid under high pressure, for example CO2 having a pressure of 60 to 70 bar. The second liquid port 9 is connected to the evaporator 2 by means of an expanded liquid pipe 10.

However, it should be noted that the valve 3 can also be operated in the opposite direction. In this case the pressures within the valve 3 are lower than in the situation illustrated above.

A liquid level 11 in the evaporator 2 is determined by a liquid level 12 in the float chamber 5. The liquid level 12 in the float chamber 5 is detected by means of the float 4. The float 4 in turn actuates the valve 3.

When the liquid level 11 in the evaporator 2 rises, the liquid level 12 in the float chamber 5 rises in the same way. The two liquid levels 11 , 12 always have the same height in the direction of gravity. When the liquid level 12 in the float chamber 5 rises, the float 4 is lifted and closes the valve 3. Thus, less liquid is supplied to the evaporator 2. When the liquid level 11 in the evaporator 2 drops, the liquid level 12 in the float chamber 5 drops as well and the float 4 moves down in the direction of gravity and opens the valve 3, so that liquid having a lower pressure than at the first liquid port 8 is supplied to the evaporator 2 by means of the expanded liquid line 10.

The float chamber 5 and the valve 3 are arranged in a common float valve arrangement 13. The float valve arrangement comprises a housing having a first part 14 and a second part 15. The second part 15 is fixed to a mounting face 16 of the first part 14. The first part 14 comprises a bore 17 in which an insert 18 is arranged. The insert 18 is shown in more detail in Fig. 4. The bore 17 is a blind bore having a bottom wall 19 in which the second liquid port 9 is arranged.

The valve 3 is arranged within the insert 18. The valve 3 comprises a cylindrical inner valve element 20 which is stationary, and a cylindrical outer valve element 21 which can be rotated around the inner valve element 20. The movement of the cylindrical outer valve element 21 is caused by the float 4 which is connected to the cylindrical outer valve element 21 by means of a lever 22.

The cylindrical inner valve element 20 comprises a hollow 23 which is directly connected to the first liquid port 8. Furthermore, the cylindrical inner valve element 20 comprises a plurality of first openings 24 which are covered by wall sections 25 of the cylindrical outer valve element 21 when the valve 3 is closed. However, when the cylindrical outer valve element 21 is rotated with respect to the cylindrical inner valve element 20, the wall sections 25 are moved away from the openings 24, so that there is a connection between the first liquid port 8 and an expansion chamber 26 arranged in the insert 18. The expansion chamber 26 is connected to the second liquid port 9. The first liquid port 8 is connected or arranged in a front face 19 of the cylindrical inner valve element 20. The hollow 23 is closed at an end opposite to the first front face 29.

The number of openings 24 is two and the number of the wall sections 25 is also two, so that there is always a pressure balance in radial direction between the two wall sections 25 and the risk that the cylindrical outer valve element 21 is stuck on the cylindrical inner valve element 20 is kept low.

The insert 18 is mounted to the first housing part 14 from the mounting face 16. When the second housing part 15 is fixed to the first housing part 14 the insert 18 is reliably held within the float valve arrangement 13. The insert 18 is sealed in the bore 17 by means of a first sealing ring 27 near the end of the insert 18 adjacent the mounting face 16 and by a second sealing ring 28 near the other end, i.e. near the second liquid port 9.

The high pressure supplied to the first liquid port 8 is kept within the hollow 23. Thus, it is basically sufficient to dimension the cylindrical inner valve element 20 so that it can withstand the high pressures of the liquid at the first liquid port 8.

When the valve 3 is open and the liquid flows through the openings 24 which are partly covered by the cylindrical outer valve element 21 , there is a pressure drop, so that the pressure in the expansion chamber 26 is much lower than at the first liquid port 8 and the other components of the float valve arrangement 13 have to be dimensioned only for these lower pressures.

The hollow 23 within the cylindrical inner valve element 20 is closed at the side from which the cylindrical outer valve element 21 is mounted. Thus, the connection between the float 4 and the cylindrical outer valve element 21 can be kept free from the high pressures at the first pressure port 8.

Claims

1. Float valve arrangement (13) comprising a housing (14, 15), a first liquid port (8), a second liquid port (9), a balance gas inlet (6), and a balance liquid inlet (7), wherein the balance gas inlet (6) and the balance liquid inlet (7) are connected to a float chamber (5) in which a float (4) is arranged, the float (4) acting on a valve (3) outside the float chamber (5), the valve (3) being arranged between the first liquid port (8) and the second liquid port (9), wherein the valve (3) comprises a cylindrical inner valve element (20) having a hollow (23) and a cylindrical outer valve element (21 ) rotatable around the inner valve element (20), wherein the float (4) acts on the outer valve element (21 ) and the first liquid port (8) is connected to the hollow (23) of the inner valve element (20), characterized in that the valve (3) is arranged within an expansion chamber (26).

2. Float valve arrangement according to claim 1 , characterized in that the inner valve element (20) comprises a first cylinder wall having a plurality of first openings (24) and the outer valve element (21 ) comprises at least a corresponding number of wall sections (25), wherein in a closed position of the valve (3) the first openings (24) are covered by the wall sections (25) of the outer valve element (21 ).

3. Float valve arrangement according to claim 2, characterized in that the number of first openings (24) is two or an integer multiple of two.

4. Float valve arrangement according to any of claims 1 to 3, characterized in that the first liquid port (8) is connected to the hollow (23) at a first front face (29) of the inner valve element (20).

5. Float valve arrangement according to claim 4, characterized in that the hollow (23) is closed at an end opposite to the first front face (29).

6. Float valve arrangement according to claim 4 or 5, characterized in that the float (4) is connected to the outer valve element (21 ) on a side opposite to the first front face (29).

7. Float valve arrangement according to any of claims 1 to 6, characterized in that the float (4) is connected to the outer valve element (21 ) by means of a lever (22) which is pivotable around a longitudinal axis of the outer valve element (21 ).

8. Float valve arrangement according to any one of the preceding claims, characterized in that the expansion chamber (26) is arranged in an insert (18) which is mounted in a bore (17) of the housing (14, 15).

9. Float valve arrangement according to claim 8, characterized in that the insert (18) comprises sealing means (27, 28) with which it is sealed to the bore (17).

10. Float valve arrangement according to claim 9, characterized in that the sealing means comprise a first sealing ring (27) at a first end portion of the insert (18) and/or a second sealing ring (28) at a second end portion of the insert (18).

11 . Float valve arrangement according to any of claims 8 to 10, characterized in that the housing comprises a first part (14) and a second part (15) fixed to a mounting (16) face of the first part (14), wherein the bore (17) comprises a bottom wall (19) opposite the mounting face (16) and the second liquid (9) port is arranged in the bottom wall (19 ).

12. Float valve arrangement according to any one of the preceding claims, characterized in that the valve (3) is an expansion valve.

13. Float valve arrangement according to any one of the preceding claims, wherein the first liquid port (8) is configured to be supplied with refrigerant under high pressure, wherein the inner valve element (20) and the outer valve ele- ment (21 ) together form throttling means through which the refrigerant has to flow to reach the second liquid port (9).