US20110308274A1

US20110308274A1 - An expansion valve comprising a diaphragm and at least two outlet openings

Info

Publication number: US20110308274A1
Application number: US13/130,060
Authority: US
Inventors: Jens Pawlik; Ejner Kobberoe; Torben Funder-Kristensen
Original assignee: Danfoss AS
Current assignee: Danfoss AS
Priority date: 2008-11-20
Filing date: 2009-11-19
Publication date: 2011-12-22
Also published as: WO2010057496A2; BRPI0921071A2; RU2481521C2; JP5543481B2; CN102292609A; EP2359080A2; MX2011005254A; WO2010057496A3; RU2011124352A; JP2012509455A

Abstract

An expansion valve (1) comprising an inlet opening and at least two outlet openings (5) is disclosed. The inlet opening is adapted to receive fluid medium in a liquid state, and the outlet openings (5) are adapted to deliver fluid medium in an at least partly gaseous state. The expansion valve (1) further comprises a diaphragm (6), and at least two valve seats (4), each valve seat (4) being fluidly connected to one of the outlet openings (5). Each of the valve seats (4) forms a valve in combination with the diaphragm (6), the position of the diaphragm (6) thereby simultaneously defining an opening degree of each of the valves. A well defined distribution of fluid flow towards each of the outlet openings (5) is easily defined by movements of the diaphragm (6). The distribution takes place before or during expansion of the fluid medium. The expansion valve (1) may be arranged in an refrigerant path of a refrigeration system.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is entitled to the benefit of and incorporates by reference essential subject matter disclosed in International Patent Application No. PCT/DK2009/000242 filed on Nov. 19, 2009 and Danish Patent Application No. PA 2008 01630 filed Nov. 20, 2008.

FIELD OF THE INVENTION

The present invention relates to an expansion valve, in particular for use in a refrigeration system, e.g. an air condition system. The expansion valve of the present invention is adapted to distribute fluid medium to at least two parallel flow paths, e.g. in the form of at least two parallel evaporators or evaporator tubes.

BACKGROUND OF THE INVENTION

In a fluid circuit, such as a refrigerant circuit of a refrigeration system, it is sometimes desirable to split the flow path into two or more parallel flow paths along part of the fluid circuit. This is, e.g., the case in refrigeration systems comprising two or more evaporators arranged in parallel. It may further be desirable to be able to control the fluid flow to each of the parallel flow paths, e.g. in such a manner that a substantially equal fluid distribution is obtained, or in such a manner that the system is operated in an optimum manner, e.g. in terms of energy consumption or efficiency.
In some previous attempts to control distribution of refrigerant between two or more parallel flow paths in a refrigeration system, a distributor is arranged downstream relative to an expansion valve in the refrigerant flow path. Thus, the refrigerant is distributed after expansion of the refrigerant, i.e. the refrigerant is mainly gaseous. This has the disadvantage that it is very difficult to control the flow of refrigerant to obtain a substantially equal distribution between the parallel flow paths.

SUMMARY OF THE INVENTION

It is an object of embodiments of the invention to provide an expansion valve which is capable of controlling distribution of fluid to two or more parallel flow paths.
It is a further object of embodiments of the invention to provide an expansion valve which is adapted to manage distribution of fluid to two or more parallel flow paths in an easy manner.
In a first aspect the present invention provides an expansion valve comprising:

- an inlet opening adapted to receive fluid medium in a liquid state,
- at least two outlet openings, each being adapted to deliver fluid medium in an at least partly gaseous state,
- a diaphragm, and
- at least two valve seats, each valve seat being fluidly connected to one of the outlet openings, and each of the valve seats forming a valve in combination with the diaphragm, the position of the diaphragm thereby simultaneously defining an opening degree of each of the valves.

The expansion valve of the invention defines flow paths between the inlet opening and the at least two outlet openings. Fluid medium in a liquid state is received at the inlet opening and fluid medium in an at least partly gaseous state is delivered at the outlet openings. In the present context the term ‘liquid state’ should be interpreted to mean that the fluid medium entering the expansion valve via the inlet opening is substantially in a liquid phase. Similarly, in the present context the term ‘at least partly gaseous state’ should be interpreted to mean that the fluid medium leaving the expansion valve via the outlet openings is completely in a gaseous phase, or at least a part, e.g. a substantial part, of the volume of the fluid medium leaving the expansion valve is in a gaseous phase. Accordingly, at least a part of the fluid medium entering the expansion valve undergoes a phase transition from the liquid phase to the gaseous phase when passing through the expansion valve.
The inlet opening and the outlet openings may preferably be fluidly connected to one or more other components, such as other components of a refrigeration system. The expansion valve may advantageously form part of a flow system, such as a flow circuit.
The expansion valve further comprises a diaphragm and at least two valve seats. Each of the valve seats is fluidly connected to one of the outlet openings. The diaphragm and the valve seats are arranged relative to each other in such a manner that each of the valve seats forms a valve in combination with the diaphragm. Since each of the valve seats is fluidly connected with one of the outlet openings, the valves formed by the valve seats and the diaphragm define fluid flow towards each of the outlet openings.
It should be noted that the valves could be formed by the valve seats and specific parts or regions of the diaphragm, e.g. in the form of valve cones or valve plates mounted on the diaphragm.
Accordingly, when the diaphragm is moved it simultaneously performs relative movements with respect to each of the valve seats, and thereby simultaneously changing the opening degrees of each of the valves formed by the valve seats and the diaphragm. Thus, the opening degrees are adjusted synchronously, thereby at least substantially maintaining a distribution key among the outlet openings. Furthermore, this is a very simple manner of simultaneously controlling fluid flow towards at least two outlet openings. Finally, the distribution of fluid medium among parallel flow paths takes place before or during expansion of the fluid medium, because the distribution takes place in the expansion valve. This makes it easier to accurately control the fluid distribution.
The expansion valve may further comprise a thermostatic element and a diaphragm moving element arranged to operatively interconnect the thermostatic element and the diaphragm, movements of the diaphragm thereby being caused by the thermostatic element. According to this embodiment, the thermostatic element determines the position of the diaphragm, and thereby the thermostatic element determines the opening degrees of each of the valves defined by the valve seats and the diaphragm. The diaphragm moving element may be arranged in direct abutment with the diaphragm. In this case movements of the diaphragm moving element in response to a pressure change of the thermostatic element will directly cause corresponding movements of the diaphragm. The diaphragm moving element may, e.g., be a block arranged in abutment with the diaphragm and connected to the thermostatic element, e.g. via a rod or a piston. The diaphragm moving element may, thus, be or comprise a piston.
As an alternative, the diaphragm may be moved in any other suitable manner, e.g. using an actuator, such as an electrical or a hydraulic actuator.
The expansion valve may further comprise means for biasing the diaphragm in a direction away from the valve seats. According to this embodiment, the diaphragm is forced towards a position defining a maximum opening degree for the valves defined by the valve seats and the diaphragm. When it is desired to decrease the opening degrees of the valves, work must be performed against the biasing force.
Alternatively, the expansion valve may further comprise means for biasing the diaphragm in a direction towards the valve seats. According to this embodiment, the diaphragm is forced towards a position defining a minimum opening degree for the valves defined by the valve seats and the diaphragm, i.e. towards a closed position. When it is desired to increase the opening degree, work must be performed against the biasing force.
In any of the embodiments described above, the biasing means may, e.g., comprise one or more springs, such as compressible springs.
The diaphragm may be provided with at least one through-going hole. This allows the diaphragm to be very flexible without requiring that the diaphragm is very thin. It is easier to manufacture the diaphragm with a certain thickness and subsequently provide a desired flexibility by providing one or more through-going holes in the diaphragm, than to directly manufacture a thin diaphragm having the desired flexibility. A flexible diaphragm ensures that the diaphragm can be moved accurately and swiftly to provide an accurate and prompt change in opening degree of the valves defined by the valve seats and the diaphragm.
Alternatively or additionally, the diaphragm may be provided with at least two valve seat engaging regions, each valve seat engaging region being arranged adjacent to a valve seat in such a manner that the valve seats and the valve seat engaging regions pair wise define the at least two valves. The valve seat engaging regions may, e.g. be parts of the diaphragm which define a level which is different from a level defined by the rest of the diaphragm. Such parts may, e.g., be in the form of ‘hills’ or ‘valleys’ formed on the diaphragm. The valve seat engaging regions may advantageously be arranged closer to the valve seats than the rest of the diaphragm. Thereby it can be ensured that the valves defined by the valve seats and the valve seat engaging regions can be closed tightly. Alternatively or additionally, the valve seat engaging regions may be or comprise valve cones or valve plates mounted on the diaphragm.
According to a second aspect the invention provides a refrigeration system comprising:

- at least one compressor,
- at least one condenser,
- at least two evaporators arranged in parallel along a refrigerant flow path of the refrigeration system, and
- an expansion valve according to the first aspect of the invention, said expansion valve being arranged in such a manner that each of the at least two outlet openings is arranged to deliver refrigerant to one of the evaporators.

Thus, the expansion valve according to the first aspect of the invention may advantageously be arranged in a refrigeration path of a refrigeration system, e.g. a refrigeration system used in a cooling arrangement or an air condition system.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the accompanying drawings in which

FIG. 1 is a cross sectional view of an expansion valve according to an embodiment of the invention,

FIG. 2 shows a first diaphragm for use in an expansion valve according to an embodiment of the invention,

FIG. 3 shows a second diaphragm for use in an expansion valve according to an embodiment of the invention, and

FIG. 4 shows a third diaphragm for use in an expansion valve according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a cross sectional view of an expansion valve 1 according to an embodiment of the invention. The expansion valve 1 comprises a first valve part 2 and a second valve part 3. The first valve part 2 has a number of valve seats 4, two of which are visible, arranged therein. Each of the valve seats 4 is fluidly connected to an outlet opening 5.
The expansion valve 1 further comprises a diaphragm 6 arranged adjacent to the first valve part 2 in such a manner that it covers the valve seats 4. Thereby movements of the diaphragm 6 relatively to the valve seats 4 define the size of a fluid passage through the valve seats 4 and towards the outlet openings 5. Thereby a number of valves are defined by the valve seats 4 and the diaphragm 6, and the opening degrees of the valves are determined by the position of the diaphragm 6 relative to the valve seats 4. A compressible spring 7 is arranged to push the diaphragm 6 in a direction towards the valve seats 4, i.e. towards a position defining a minimum opening degree for the valves defined by the valve seats 4 and the diaphragm 6.
The diaphragm 6 is operatively connected to a thermostatic element (not shown) via a piston 8. The thermostatic element controls movements of the piston 8 as indicated by arrow 9, thereby controlling movement of the diaphragm 6. When the piston 8 is moved in a downwards direction, i.e. in a direction towards the position of the diaphragm 6, the diaphragm 6 is pushed in a direction away from the valve seats 4. Thereby the size of passages defined between the diaphragm 6 and each of the valve seats 4 is increased, thereby increasing the opening degrees of the valves defined by the valve seats 4 and the diaphragm 6. When the piston 8 is moved in the opposite direction, the diaphragm 6 is moved in a direction towards the valve seats 4 by the spring 7, i.e. the opening degrees of the valves defined by the valve seats 4 and the diaphragm 6 are decreased.
The expansion valve 1 of FIG. 1 may be operated in the following manner. Fluid medium in a substantially liquid state is received in the expansion valve 1 via an inlet opening (not shown) arranged in an upper part of the piston 8. The fluid medium is led through the piston 8 towards the diaphragm 6 and further towards the valve seats 4. Depending on the position of the diaphragm 6, and thereby the opening degrees of the valves defined by the valve seats 4 and the diaphragm 6, the fluid is led through the valve seats 4 and leaves the expansion valve 1 via the outlet openings 5. During this the fluid medium is expanded, and the fluid medium leaving the expansion valve 1 via the outlet openings 5 is therefore in an at least partly gaseous state.
FIG. 2 shows a diaphragm 6 which is suitable for use in the expansion valve 1 of FIG. 1. The diaphragm 6 is provided with four through-going holes 10. When the diaphragm 6 is mounted in an expansion valve 1 it is positioned in such a manner that the through-going holes 10 are not arranged at positions corresponding to valve seats 4. Thereby the diaphragm 6 is capable of providing a required sealing effect towards the valve seats 4.
Since the diaphragm 6 is provided with through-going holes 10 it is more flexible than a diaphragm having the same thickness, but without the through-going holes 10. The increased flexibility allows the diaphragm 6 to react fast to movements of the piston 8 in response to changes in the thermostatic element. Thereby the response time of the valve is reduced. Furthermore, a more accurate positioning of the diaphragm 6 can be obtained, and thereby it is possible to adjust the opening degrees of the valves defined by the valve seats 4 and the diaphragm 6 more accurately.
FIG. 3 shows an alternative diaphragm 6 which is suitable for use in the expansion valve 1 of FIG. 1. In the lower part of FIG. 3 the diaphragm 6 is seen from above, and in the upper part of FIG. 3 the diaphragm 6 is shown in a cross sectional view.
The diaphragm 6 of FIG. 3 is provided with four elevated regions 11. When the diaphragm 6 is mounted in an expansion valve 1 it is positioned in such a manner that the elevated regions 11 are arranged at positions corresponding to the positions of the valve seats 4, and in such a manner that the elevated regions 11 are arranged closer to the first valve part 2 than the remaining part of the diaphragm 6. Thereby it can be ensured that a substantially fluid tight fit is provided between the diaphragm 6 and the valve seats 4 when the diaphragm 6 is in the position defining a minimum opening degree of the valves.
FIG. 4 shows yet an alternative diaphragm 6 which is suitable for use in the expansion valve 1 of FIG. 1. The diaphragm 6 of FIG. 4 is very similar to the diaphragm 6 of FIG. 3, since the diaphragm 6 of FIG. 4 is also provided with elevated regions 11. However, the elevated regions 11 of FIG. 4 are shaped in a slightly different manner.
While the present invention has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this invention may be made without departing from the spirit and scope of the present.

Claims

1. An expansion valve comprising:

an inlet opening adapted to receive fluid medium in a liquid state,

at least two outlet openings, each being adapted to deliver fluid medium in an at least partly gaseous state,

a diaphragm, and

at least two valve seats, each valve seat being fluidly connected to one of the outlet openings, and each of the valve seats forming a valve in combination with the diaphragm, the position of the diaphragm thereby simultaneously defining an opening degree of each of the valves.

2. The expansion valve according to claim 1, further comprising a thermostatic element and a diaphragm moving element arranged to operatively interconnect the thermostatic element and the diaphragm, movements of the diaphragm thereby being caused by the thermostatic element.

3. The expansion valve according to claim 2, wherein the diaphragm moving element is arranged in direct abutment with the diaphragm.

4. The expansion valve according to claim 2, wherein the diaphragm moving element is or comprises a piston.

5. The expansion valve according to claim 1, further comprising means for biasing the diaphragm in a direction away from the valve seats.

6. The expansion valve according to claim 1, further comprising means for biasing the diaphragm in a direction towards the valve seats.

7. The expansion valve according to claim 1, wherein the diaphragm is provided with at least one through-going hole.

8. The expansion valve according to claim 1, wherein the diaphragm is provided with at least two valve seat engaging regions, each valve seat engaging region being arranged adjacent to a valve seat in such a manner that the valve seats and the valve seat engaging regions pair wise define the at least two valves.

9. A refrigeration system comprising:

at least one compressor,

at least one condenser,

at least two evaporators arranged in parallel along a refrigerant flow path of the refrigeration system, and

an expansion valve according to claim 1, said expansion valve being arranged in such a manner that each of the at least two outlet openings is arranged to deliver refrigerant to one of the evaporators.