Field The present invention relates to valves for controlling the flow of fluids in systems which use pipes, such as but not limited to refrigeration systems.

Background The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Refrigeration systems cycle a refrigerant around a piped network of evaporators, condensers, compressors, expansions valves and other heat exchange devices. During the refrigeration cycle heat is repeatedly transferred to and from the refrigerant, and as this occurs, the refrigerant undergoes several pressure and phase changes.

The pipes used in refrigeration systems are typically selected to withstand increases in pressure of the refrigerant. Often, during maintenance and repair, certain sections of the piped network are closed off by valves stopping the flow of refrigerant. Refrigerant trapped in closed off portions of the network can warm significantly and the associated increase in refrigerant pressure can lead to pipe damage or system failure.

In seeking to address this issue, existing refrigerant systems have included pressure release valves at multiple points along the refrigerant circulation network. Pressure is then manually released at different points along the piping network. Often the number of pressure release valves required can make installation expensive and time consuming. An alternative approach to address this issue is to install separate bypass lines between closed off sections of the piped network. The bypass lines include a check valve which allows fluid to pass through the separate bypass line when the pressure builds to a point which opens the check valve. However, the fitting of separate bypass lines is labour intensive and usually requires the installation of further insulation. Moreover, as fitting of a bypass line is a patchwork solution, leakage of refrigerant from such a system commonly occurs.

Summary of the Invention

According to one aspect the present invention provides a valve assembly for controlling the flow of a fluid, the valve assembly including a main body with an inlet and an outlet, the main body including:

a primary fluid flow path from the inlet to the outlet, the primary flow path being closable by a first valve member; and,

a secondary fluid flow path providing an alternative flow path from the inlet to the outlet, the secondary fluid flow path being closable by a second valve member, wherein a pressure difference between the fluid at the inlet and the fluid at the outlet causes the second valve member to open and allow the fluid to flow via the secondary fluid flow path.

In one form, the second valve member is biased towards a closed position. In one form, the second valve member opens to substantially equalise the pressure of the fluid at the inlet and the fluid at the outlet when the first valve member is closed.

In one form, the second valve member is biased by a spring. In one form the second valve member opens when the force exerted thereon resulting from the pressure difference between the fluid at the inlet and the fluid at the outlet is greater than the biasing force of the spring. In a further form, the closed position of the second valve member has the second valve member seated in a valve seat formed by a constriction in the secondary fluid flow path.

In one form, the spring engages the second valve member from the inlet side such that when the fluid pressure at the outlet side of the second valve member is higher than the fluid pressure at the inlet side of the second valve member, and the force applied to the second valve resulting from the pressure difference is greater than the biasing force of the spring, the second valve member moves off the valve seat, compressing the spring, and allowing fluid to flow through the secondary fluid flow path.

In one form, the primary flow path is formed of a primary bore extending between the inlet and outlet.

In one form, the secondary flow path is formed of a bored bypass that branches off the primary bore to bypass the first valve member and re-merges with the primary bore on the other side of the first valve member.

In one form, the first valve member is a ball valve. In one form, the fluid is a refrigerant.

In a further form the valve assembly is for use in a refrigeration system.

In a further form the valve assembly is formed of a single body.

In a further form the valve assembly is hermetically sealed.

Brief Description of the figures Examples of the present invention will now be described with reference to the accompanying figures, in which: Figure 1 is a sectional view of the valve according to one example of the invention; and,

Figure 2 indicates an example of the direction of flow of refrigerant for the valve of figure 1.

Detailed Description

The foregoing describes only some embodiments of the present invention, and modifications and/or changes can be made thereto without departing from the scope and spirit of the invention, the embodiments being illustrative and not restrictive.

In the context of this specification, the word "comprising" means "including principally but not necessarily solely" or "having" or "including", and not "consisting only of. Variations of the word "comprising", such as "comprise" and "comprises" have correspondingly varied meanings.

Examples of the present invention provide a valve assembly for controlling the flow of a fluid, the valve assembly including a main body with an inlet and an outlet. The valve assembly includes a first fluid flow path from the inlet to the outlet and the primary fluid flow path is closable by a first valve member. The valve assembly also includes a secondary fluid flow path providing an alternative flow path from the inlet to the outlet, the secondary flow path being closable by a second valve member. A pressure difference between the fluid at the inlet and the fluid to the outlet causes the second valve member to open and allow the fluid to flow via the secondary flow path.

One embodiment of the invention is shown by the refrigeration system valve assembly shown in figure 1. The valve assembly (1) includes a main body (2) having an inlet (3) and an outlet (4). A primary fluid flow path (5) extends from the inlet (3) to the outlet (4) and is closable by ball valve (6). A secondary fluid flow path (7) provides an alternate flow path from the inlet (3) to the outlet (4). The secondary flow path is closable by a second valve member (8). The second valve member (8) is biased towards a closed position by a spring (9).

When the refrigeration system is in normal operation, the primary fluid flow path (5) is open and the ball valve (6) allows refrigerant to pass through the valve assembly (1). Flow is determined by pressure or gravity and can operate in either direction.

When the ball valve (6) is closed and the flow through the primary fluid flow (5) path has stopped, the fluid pressure on each side of the valve assembly (1) is able to change independently. For example the fluid pressure on each side of the valve may remain the same, or may rise or fall depending on the location of the valve assembly (1) and application that the valve assembly (1) is being used for.

If the pressure downstream (at the outlet side) from the closed ball valve (6) rises, the system may be in danger of pipe or device failure due to over pressurization. The valve assembly (1) provides that in this situation the secondary fluid flow path (7) will open and allow refrigerant to pass through, bypassing the closed ball valve (6). The pressure is thereby relieved to a location where the system is protected by a pressure relief valve. When the ball valve (6) is closed the second valve member (8) can open to substantially equalise the pressure of the fluid at the inlet (3) and the fluid at the outlet (4).

The second valve member (8) opens when the force on the second valve member resulting from the pressure difference between the fluid at the inlet (3) and the fluid at the outlet (4) is greater than the biasing force of the spring (9).

The second valve member (8) and spring (9) arrangement is integrated into the secondary flow path (7) and in the embodiment of figure 1, the length of the spring is positioned parallel to the primary flow path. In the closed position, the second valve member (8) is seated in a valve seat (10) formed by a constriction (11) in the secondary fluid flow path (7). The spring (9) engages the second valve member (8) from the inlet side, the force of the spring pressing the second valve member (8) into the valve seat (10). When the fluid pressure at the outlet side of the second valve member (4a) is higher than the fluid pressure at the inlet side of the second valve member (3 a), and the force on the second valve member (8) resulting from the pressure difference is greater than the biasing force of the spring (9), the second valve member (8) is forced off the valve seat (10), compressing the spring (11), and allowing fluid to flow through the secondary fluid flow path (7).

Referring to figure 2, if the pressure at "b" is higher than the pressure at "a" the second valve member will open and the pressure will equalize between "a" and "b". However, if the pressure at "a" is higher than "b" the second valve member will remain closed and the pressure will be maintained at "a" and "b".

The primary fluid flow path (5) is formed of a primary bore extending between the inlet and the outlet. The secondary flow path is formed of a bored bypass that branches off the primary bore to bypass the ball valve (6) and thereafter re-merges with the primary bore on the other side of the ball valve (6). As the primary and secondary flow paths are formed by boring through a single body, the entire valve assembly (1), apart from the openings at the inlet and outlet, is hermetically sealed such that there is no possibility for leakage of refrigerant.

The valve assembly (1) effectively has an internal relief function which allows refrigerant liquid, vapour or super critical fluid to bypass the ball valve (6) in the event that the pressure on outlet (4) side of the valve assembly is higher than the pressure on the inlet (3) side. This prevents the need to have a pressure relief valve on both sides of the valve assembly or to fit an external check valve which would be piped around a standard valve.

Although in figure 1 the primary fluid flow path (5) is closable by a ball valve (6), the first valve member, for closing the primary flow path, is not limited to ball valves. For example the first valve member may be a solenoid valve, globe valve, packed cap valve, diaphragm valve, stop valve or stop check valve. It is apparent that the embodiments of figures 1 and 2 only allow refrigerant to bypass the first valve member (ball valve) in one direction. However other embodiments may be capable of relieving high fluid pressures on both sides of the valve assembly. For example, this could be achieved by incorporating a further flow path with a spring biased valve which mirrors that of the secondary flow path. Alternatively a different biased valve member for the secondary flow path could be used, such as a flapping leaf spring. Such an alternate mechanism could allow fluid flow in either direction to equalise fluid pressure across the valve.

Optional embodiments of the present invention may also be said to broadly consist in the parts, elements and features referred to or indicated herein, individually or collectively, in any or all combinations of two or more of the parts, elements or features, and wherein specific integers are mentioned herein which have known equivalents in the art to which the invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

Although a preferred embodiment has been described in detail, it should be understood that various changes, substitutions, and alterations can be made by one of ordinary skill in the art without departing from the scope of the present invention.

It will be appreciated that various forms of the invention may be used individually or in combination.