US3762180A

US3762180A - Refrigerant valve

Info

Publication number: US3762180A
Authority: US
Inventors: H Jespersen
Original assignee: Danfoss AS
Current assignee: Danfoss AS
Priority date: 1971-10-05
Filing date: 1971-10-05
Publication date: 1973-10-02
Anticipated expiration: 1990-10-02

Abstract

The invention relates to a refrigerant valve assembly of the type in which the actuating spindle attached to the valve is loaded at one end by a diaphragm pressure unit and at the other end by a spring. The diaphragm pressure unit includes a diaphragm with first and second chambers on opposite sides of the diaphragm. A bellows surrounding the diaphragm end of the spindle is disposed in one of the chambers and fluid communication is provided between the valve working chamber and the space internally of the bellows. Fluid communication is also provided between chamber in which the bellows is disposed and the valve working chamber. The object is to provide a dry gas in the chamber in which the bellows is disposed to prevent icing of the end of the spindle due to condensation.

Description

United States Patent n 1 Jespersen 1 Oct. 2, 1973 l REFRIGERANT VALVE [75] Inventor: Hans Jorgen Jespersen, Sonderborg,

[22] Filed: Oct. 5, 1971 [21] Appl. No.: 186,615

[52] U.S. Cl 62/223, 236/92 R, 'l37/505.29

Primary ExaminerMeyer Perlin Attorney-Wayne B. Easton [57] ABSTRACT The invention relates to a refrigerant valve assembly of the type in which the actuating spindle attached to the valve is loaded at one end by a diaphragm pressure unit and at the other end by a spring. The diaphragm pressure unit includes a diaphragm with first and second chambers on opposite sides of the diaphragm. A bellows surrounding the diaphragm end of the spindle is disposed in one of the chambers and fluid communication is provided between the valve working chamber and the space internally of the bellows. Fluid communication is also provided between chamber in which the bellows is disposed and the valve working chamber. The object is to provide a dry gas in the chamber in which the bellows is disposed to prevent icing of the end of the spindle due to condensation.

2 Claims, 2 Drawing Figures REFRIGERANT VALVE The invention relates to a refrigerant valve in which the actuating spindle is loaded at one end by diaphragm pressure unit and at the other by a spring.

Valves of this kind are known for example for handling liquid nitrogen which is sprayed through nozzles into a compartment to be cooled where it vaporizes and thus produces cold. The valve is however suitable for other refrigerants e.g. fluoro-chlorinated hydrocarbons.

On account of the pressure-drop which the refrigerant undergoes in valves of this kind, the valves become cooled. This leads to moisture in the surrounding atmosphere becoming deposited, and the valve ices up. If the coating of ice is formed on movable parts of the valve it becomes incapable of functioning. This occurs even in normal atmospheric air but particularly so when the valve is in a cold compartment in which substances such as food-stuffs that give of moisture are stored.

These difficulties do not occur in a refrigerant valve in which the spindle extends without sealing means from the working chamber of the valve through a gland to the diaphragm, since then all the moving parts of the valve are located in the refrigerant. With an arrangement of this kind however it has to be accepted that the entire diaphragm is affected by the pressure of the refrigerant. This has an adverse effect upon the accuracy of response of the valve or, when the pressurized medium available for control purposes is at low pressure, accuracy of response is hazarded.

The object of the invention is to provide a refrigerant valve of the initially described kind which, as well as being unaffected by atmospheric moisture, also possesses great accuracy in the manner in which it responds.

According to the invention, this object is achieved by that end of the spindle presented to the diaphragm being surrounded by a bellows which tightly seals off the space accommodating the spindle and connected to the working chamber of the valve and which has a small area in comparison with the area of the diaphragm, and by the bellows being surrounded by a chamber which is sealed off from the surrounding atmosphere and which contains a charge, preferably of dry gas, which is at a lower pressure than the refrigerant.

In this arrangement, only the interior of the bellows is subjected to the pressure of the refrigerant. Since this pressure acts on only a small portion of the area of the diaphragm, interference is very slight. The gas charge in the sealed-off chamber outside the bellows protects the exterior of the bellows and that face of the bellows presented to the spindle against contact with moisture in the atmosphere. Since the interior of the pressure unit is in any case sealed off against the atmosphere, and the remaining cavity in the valve is filled with refrigerant, no danger arises of the formation of ice on the movable parts of the valve. Since the gas pressure in the sealed-off space is substantially constant, it can be taken into account by an appropriate rating of the valve spring.

It is advantageous if the gas is at a pressure less than atmospheric pressure. The gas charge can be so small that the sealed-off space has to be regarded as being evacuated. The vacuum offers the advantage that relatively low pressures can be used in the control system. In the case of a refrigerant valve for a refrigerant, e.g.

liquid nitrogen, to be introduced into the cold compartment, then in accordance with the invention the same problem can be solved by that end of the spindle presented to the diaphragm being surrounded by a bellows which tightly seals off the space accommodating the spindle and connected to the working chamber of the valve, and which has a small area in comparison with the area of the diaphragm, and by the bellows being surrounded by a chamber substantially selaed off against the surrounding atmosphere, through which chamber a flow-restricting passage extends from the outlet side of the valve to the surrounding atmosphere.

In this arrangement the effect of the full pressure of the refrigerant on the diaphragm is kept small. The pressure in the chamber surrounding the bellows can be kept low with the aid of the flow-restricting passage and particularly by the flow-restricting passage having a flow-restricting point upstream and downstream of the sealed-off space, the first of these points having a stronger flow-resisting effect than the second. No trouble is caused if moist atmospheric air penetrates into the sealed-off space when the valve is in the closed position, since the amount of air can only be small and this does not lead to icing up and can be discharged by the refrigerant flowing away through the flowrestricting passage the next time the valve is opened. This leakage causes no trouble since the amount involved is very small and since the refrigerant is in any case sprayed into the surrounding chamber.

The invention will now be described in more detail by reference to embodiments illustrated in the drawing, in which:

FIG.-1 is a longitudinal section through a refrigerant valvev constructed in accordance with the invention, and

FIG. 2 shows the upper part of another embodiment.

The refrigerant valve of FIG. 1 has a casing 1 with an inlet port 2 and an outlet port 3.. It is secured by means' of screws 4. A valve spindle 5 is mounted in a guide 6 solid with the casing. A closure member 7 cooperates with a valve seal 8. A spring 9 biases the valve spindle in the upward direction. The diaphragm ll of a pressure unit 12 acts on the upper end of the spindle through a pressure cap 10. The pressure unit may be connected by way of a port to a control pipe for pressurized medium. This pressure unit can be actuate pressostatically or thermostatically.

That end of the spindle 5 presented to the diaphragm is surrounded by a bellows 13 so that a space 14 foraccommodating the spindle is created and this communicates with the outlet side or the valve and is tightly sealed off. Outside the bellows is a chamber 15 which is bounded by the bellows, the diaphragm and parts of the casing. Through this chamber extends a flowrestricting passage which consists of a first section 16, between the outlet side of the valve and the chamber 15, and a second section 17, between the chamber 15 and the surrounding atmosphere.

If the pressure in the pressure unit 12 is too low, the valve occupies the closed position as illustrated. If the control pressure rises, the valve opens and liquid refrigerantis discharged through the port 3. The pressure of the refrigerant is also exerted in the interior 14 of the bellows 13. Since the area of the bellows is approximately l2'times smaller than the area of the diaphragm, this counter-force results in only slight interference. A small portion of. the liquid refrigerant passes through section 16 of the flow-restricting passage and into the chamber 15. It vaporizes and passes to the exterior through the section 17, and in so doing entrains all the moisture contained in the chamber 15. The pressure in the chamber can be kept low enough not to interfere with the regulating action of the valve. When the valve closes, the pressure drops on the outlet side of the valve, in .the chamber 15 and in

sections

16 and 17 of the passage to a level correspoinding to the pressure of the surrounding atmosphere. At most only very small quantities of air from the surrounding atmosphere are able to pass through section 17 of the passage into the chamber 15 and this air is flushed out again the next time the valve is opened.

FIG. 2 illustrates the valve of FIG. 1 but with a different upper part. Like elements are designated by the same reference numerals as in H0. 1. The pressurized medium is supplied through a capillary tube 18. The diaphragm 11, the bellows 13 and parts of the casing define a space 19 which is sealed off against the surrounding atmosphere. A closed connecting port 20 is used for evacuating the space 19 and for charging it with a small quantity of appropriately dry gas. Instead of this, the space 19 may also be completely evacuated through the port 20.

I claim:

I. A refrigerant valve assembly comprising a valve body having inlet and outlet ports with a working chamber between said ports, a diaphragm pressure unit connected to said valve body which includes a diaphragm with first and second chambers on opposite sides of said diaphragm, spring means. a valve for one of said ports, a spindle attached to said valve and being loaded in one direction by said diaphragm pressure unit and in the opposite direction by said spring means. a bellows disposed in said first chamber and surrounding the diaphragm end of said spindle, said valve body having a first passage providing fluid communication be tween the interior of said bellows and said working chamber, said valve body having a second passage providing fluid communication between said first chamber and the exterior of said valve assembly, said valve body having a third passage providing fluid communication between said first chamber and said working chamber.

2. A refrigerant valve assembly according to claim I wherein said second passage has stronger flow restricting characteristics than said third passage.

Claims

1. A refrigerant valve assembly comprising a valve body having inlet and outlet ports with a working chamber between said ports, a diaphragm pressure unit connected to said valve body which includes a diaphragm with first and second chambers on opposite sides of said diaphragm, spring means, a valve for one of said ports, a spindle attached to said valve and being loaded in one direction by said diaphragm pressure unit and in the opposite direction by said spring means, a bellows disposed in said first chamber and surrounding the diaphragm end of said spindle, said valve body having a first passage providing fluid communication between the interior of said bellows and said working chamber, said valve body having a second passage providing fluid communication between said first chamber and the exterior of said valve assembly, said valve body having a third passage providing fluid communication between said first chamber and said working chamber.

2. A refrigerant valve assembly according to claim 1 wherein said second passage has stronger flow restricting characteristics than said third passage.