DE1751260A1 - Thermostatically controlled expansion valve for refrigeration systems - Google Patents

Description

DR.-INQ. ULRICH GARLIC PATEISiTAKlUVAI T PRANKrURT / MAIN 1, DEN

ij- »i er« IMlH WAU I KDHHORN8HOf = WEQ IO

PO3T3CHECK ACCOUNT FRANKFURT / M. 34 pp

DRESDNER. BANK. FRANKFURT / M. 003 708 TELEPHONE: SO OS 07 »

TELEQRAM: KNOPAT Λ / .Γ

HIiFOSS A / S, Nordborg (Denmark)

Thermostatically controlled expansion valve for

Refrigeration systems

The invention relates to a thermostatiech controlled Expansion valve for refrigeration systems. "

In such an expansion valve, the closure piece must be able to assume any intermediate position between the fully open and the fully closed position. This task is fulfilled to the full satisfaction of the usual expansion valves, in which the closure piece is adjusted directly by the thermostatic working element against the force of a setpoint spring. The thermostatic working element can also be directly connected to the vapor space of the refrigerant system. However, such a valve is not sufficient in larger refrigeration systems because the flow rate of such a thermostatically controlled valve is limited. (

A valve arrangement has therefore become known in which the usual thermostatically controlled expansion valve only has one Auxiliary valve that is connected to a main valve via a pipeline. The auxiliary valve controls the flow through a Throttle, the pressure drop of which actuates the main valve Piston adjusted against the force of a counter-pressure spring supported on the housing. In this known arrangement, however, occurred frequent blows or vibrations. Auoh followed the

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The main valve end piece is not always in the desired manner the control movements of the auxiliary valve; rather it tended to to go to the full open or closed position.

Furthermore, a suction pressure regulator for refrigeration systems is known, which in turn consists of an auxiliary valve and a main valve connected to it via a line. The locking piece of the The main valve closes in the direction of flow and is but one Shank connected to a piston which has a considerably larger cross-section than the locking piece and is supported on the side facing away from the locking piece with the housing fixed Counter pressure spring is loaded. Again, the piston is under the influence of a differential pressure which occurs at a throttle, the flow of which is controlled by the auxiliary valve. This suction pressure regulator is only intended to allow vaporous refrigerant to pass through. The main valve can essentially only be one take up fully open or fully closed position.

A valve arrangement is required for a water pipe, in which a thermostatically controlled auxiliary valve and a main valve controlled by it are combined to form a structural unit. The auxiliary valve in turn controls the flow through a throttle. The pressure drop across the throttle controls a cylinder which forms the closing piece of the main valve and which closes against the direction of flow. Its counter-pressure spring is not supported on the housing but on the shaft of the auxiliary valve. The latter results in a feedback that enables good proportionality between the position of the auxiliary valve and the position of the main valve.

The invention is based on the object of specifying a thermostatically controlled expansion valve which is also suitable for large refrigeration systems, works more easily and has a favorable operating characteristic.

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This object is achieved according to the invention by the combination of the following known features:

a) A thermostatically operated auxiliary valve controls the flow by a throttle, the pressure drop of which pushes a piston actuating a main valve against the force of a counter-pressure spring adjusted.

b) The auxiliary valve is combined with the main valve in one unit and the counter-pressure spring is supported on the shaft of the auxiliary valve and acts against the force of the thermostat! - see working element.

c) The closure piece of the main valve closes in the direction of flow and is connected to that in a cylinder via a shaft arranged piston connected, which has a significantly larger cross-section than the closure piece and on the Closing piece facing away from the side is loaded with the counter-pressure spring.

With this combination the problems that are in it are overcome lie that the refrigerant is in the liquid state of aggregation, but as intended quickly in the vapor state should cross. But if the evaporation occurs before ' Reaching the expansion valve takes place, the valve assembly is capable no longer work properly. Due to the large piston cross-section, based on the cross-section of the main valve vers chlßstticks, you can get a sufficient stroke with a smaller one Reach pressure drop at the throttle. As a result, this pressure drop can be kept so small that it does not lead to the formation of steam leads. Furthermore, the auxiliary valve is connected to the main valve to form a structural unit, so that not in one Intermediate line a warming and therefore evaporation of the to Auxiliary valve flowing refrigerant can evaporate. In the extra

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OWQiNAL INSPECTED

If so, the valve seat of the auxiliary valve can even be in the room above the piston. If, however, it is ensured in this way that liquid refrigerant is available up to the auxiliary valve, then a valve construction can also be used, which has proven itself in a water pipe. The fact that the closure piece of the main valve closes in the direction of flow is taken into account the forces that the refrigerant flowing through under considerable pressure drop on the closure piece exercises.

The shaft preferably penetrates a bottom that closes off the cylinder and the spaces on both sides of it are over one Throttle channel connected * With this measure one achieves a • hydraulic damping, because during the closing movement of the piston between him and the bottom liquid must displace through the throttle channel.

Furthermore, the throttle generating the pressure drop across the piston should have a greater throttle resistance than that of the throttle channel. In this way it is ensured that, despite the desired damping effect, the pressure drop for the Auxiliary valve flowing? Refrigerant in the Droseel Canal is negligibly small.

In a preferred embodiment, the closure piece has a needle-like flow body and adjoining it a sealing circumferential edge, which at the same time serves as a stop for the piston movement is used. The flow body can be designed in such a way that a predetermined flow cross section is released as a function of the stroke. Furthermore, the shaft can with the valve piece be formed in one piece and the same Have the same diameter as its maximum diameter *

'Ά Ö.Q 9 8 3 5 / O 6 9 6

The invention is explained in more detail below with reference to an exemplary embodiment shown in the drawing. The drawing shows a longitudinal section through an expansion valve according to the invention.

A valve seat 4 for a main valve is located in a housing 1 with an inlet connection 2 and an outlet connection 3. This has a closure piece 5 with a needle-like flow body 6 and a sealing peripheral edge 7 »which is an end stop forms. The closure piece 5 is via a shaft 8 which has the same diameter as the largest diameter of the echlußstücks 5, connected to a piston 9. The piston has a cross section that is many times larger than that of the closure piece 5 »especially in the area of the sealing edge The valve seat is held in an insert 10 that is attached to the top The end forms a cylinder 11 in which the piston 9 is axially displaceable. The shaft 8 is guided through a bottom 12, which the space 13 above the valve seat 4 from the space 14 below half of the cylinder 9 separates. A throttle duct 15 in use 10 connects the spaces 13 and 14. A throttle 16 in the piston 9 connects the space 14 with the space 17 above the piston 9. In addition, the piston is loaded by a Gegenruokfeder 18, which supported on a plate 19. . (

A valve seat is located between an attachment 20 and an insert 21

22 attached for an auxiliary valve with a closure piece

23 cooperates. The valve stem 24 of this auxiliary valve is pressed upwards by a setpoint spring 25 'which acts on a plate 26, while the membrane 27 of a thermostatic working element 28 influences the stem 24 in the opposite direction via a plate 29. The working element is connected via a capillary tube 30 to a sensor 31 which is attached to the evaporator. Zr contains a plume vapor deposition. At the lower end, the Sohaft 24 acts on the plate 19

ORWHNAL INSPSCTEO 009835/0696

From a space 32 above the auxiliary valve seat 20 leads Channel 33 to the outlet nozzle 3.

During operation, liquid refrigerant is present at the inlet connection 2. When the auxiliary valve and main valve are closed, it can pass through space 13, throttle duct 15, space H, throttle duct 16 to space 17 can expand. As a result, there is a pressure drop across the throttle 16. This pressure drop causes the piston 9 to move upwards. As a result! Essen opens the main valve and a portion of the refrigerant which is approximately proportional to the part of the refrigerant flowing through the auxiliary valve also flows out via the main valve , diamine tightly coupled movement between the locking piece of the auxiliary valve and the locking piece of the main valve ensures. When the auxiliary valve closes again, the pressure difference no longer acts on the piston, it moves down again, whereby the refrigerant flowing through the main valve creates a considerable force During this closing movement, liquid refrigerant is displaced from space 14 through throttle 16 into space 17 and through throttle channel 15 into space 13 *.

As already mentioned, the thermostatic working element 28 can also be connected directly to a part of the refrigeration system that carries refrigerant vapor. It is also advantageous in this arrangement that leakage fluid that is on the outside the piston seeps through, has to flow out via the auxiliary valve, so that the Leokverluate do not result in any falsification of the operating mode.

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Claims (6)

Λ. Claims: inriocn ι / bI ZbU 1. Thermostatically controlled expansion valve for refrigeration systems, characterized by the combination of the following known features: a) A thermostatically operated auxiliary valve (22,23) controls the flow through a throttle (16), the pressure drop a main valve (4,5) actuating piston is displaced against the force of a counter-pressure spring (18). b) The auxiliary valve is combined with the main valve in one unit and the counter-pressure spring is supported on the shaft (24) of the auxiliary valve and acts against the | Power of the thermostatic working element / 28 ^ c) The closure piece (5) of the main valve closes in Direction of flow and is connected to the piston (9) arranged in a cylinder (11) via a shaft (8), which has a considerably larger cross-section than that Closure piece and is loaded on the side facing away from the closure piece with the counter-pressure spring ii8). 2. Expansion valve according to claim 1, characterized in that the shaft (8) has a bottom that closes off the cylinder (11) (12) penetrated and the rooms (13 »14) on both sides are connected via a throttle channel (15). * 3. Expansion valve according to claim 1 or 2, characterized in that that the pressure drop across the piston (9) generating throttle (16) has a greater throttle resistance than that of the Throttle duct (15) 3 5/0 C q 4 ·. Expansion valve according to one of Claims 1 to 3, characterized characterized in that the valve seat (22) of the auxiliary valve is located in the space (70) above the piston (9). 5. Expansion valve according to one of claims 1 to 4, characterized characterized in that the Verschufletüok (5) is a needle-like Flow body (6) and adjoining it has a sealing peripheral edge (7), which also acts as a stop for the piston movement is used. 6. Expansion valve according to one of claims 1 to 5 »thereby characterized in that the shaft (θ) with the locking piece (5) »Is made in one piece and has the same diameter as whose largest diameter has. 009835 / 069G