DE102021118962A1 - Control flow control valve for scroll compressors - Google Patents

Abstract

The invention relates to a control flow control valve (1) for spiral compressors, consisting at least of a housing (8) and a closure element (9) as well as fluid connections (2, 3, 4) for the control flow, for the back pressure (Pb), for the high pressure (Pd ) and for the suction pressure (Ps) with the effective surfaces on the closure element (9) assigned to the connections, characterized in that the closure element (9) is used to seal the low-pressure space (12) with an effective diameter of the low-pressure space (d24) from the counter-pressure space (11) with an effective diameter The counter-pressure chamber (d25) has exactly one diaphragm seal (7), which is arranged on the closure element (9), with the low-pressure chamber (12) on one side of the diaphragm seal (7) and the counter-pressure chamber (11) on the other side of the diaphragm seal (7). is arranged, wherein the shape of the membrane seal (7) is selected such that it has a definable contour-dependent spring stiffness, which fes the force-displacement function of the closure element (9). puts

Description

The invention relates to a control flow control valve for scroll compressors, the valve having a plurality of fluid connections for one or more fluids at different pressure levels.

The field of application of the invention relates in particular to electrically and mechanically driven refrigerant compressors using the compression principle of the spiral compressor, which is also referred to as a scroll compressor.

Scroll compressors consist of a fixed scroll, the FixScroll, which is permanently installed in the compressor, and an orbiting scroll, the OrbitingScroll, which orbits within the FixScroll with a mechanically specified radius, i.e. rotates. The movement of the OrbitingScroll creates pairs of chambers between the two spiral or scroll halves, the volume of which is reduced by the inward movement. This compresses the internal gas in the chambers.

The pressure increase in the parallel chambers creates a force on the OrbitingScroll that would cause the axial seals to open. In addition, this axial force does not act on the OrbitingScroll in the middle, which means that a tilting moment would detach the OrbitingScroll from the FixScroll on one side, which is also referred to as overturning torque.

In the prior art, there are primarily two methods for counteracting these two forces with a corresponding counterforce. On the one hand there are scroll compressors with orbiting axial bearings and on the other hand this force is compensated or even overcompensated by a corresponding back pressure, the so-called back pressure pressure, in a pressure chamber behind the orbiting scroll.

In order to ensure safe operation of the scroll under all operating conditions, it must be ensured for all conditions that the force emanating from the back pressure pressure dominates the balance of forces around the orbiting scroll. Otherwise, the scroll would open its axial sealing surfaces and, in extreme cases, stop compressing the gas. The necessary back pressure varies depending on the pressure applied, internal tightness and other parameters.

On the other hand, too high a back pressure in the balance of forces around the OrbitingScroll causes excessive friction and thus wear on the components.

In the prior art, the back pressure is formed by a nozzle system as a function of the high pressure and the suction pressure. For this purpose, two nozzles with flow losses are tuned in such a way that a suitable mean pressure, the back pressure, is set in all cases.

In the prior art, the back pressure pressure is alternatively, for example, after U.S. 2010/0158710 A1 formed with a spring-loaded, mechanical control valve on the back-pressure chamber supplying or discharging side.

From the DE 10 2013 021 250 A1 a scroll machine and a method for its operation is known, wherein a control element is provided between the counter-pressure chamber and the low-pressure port in order to control a counter-pressure as a function of a pressure difference of the fluid between the high-pressure port and the low-pressure port.

the US 2010/0 209 819 A1 discloses an ejector and a fuel cell system with an ejector with a regulation for the outlet pressure of the fluid by means of a valve.

In a further variant of the prior art, there are combinations of nozzles and pressure-controlled on/off valve on the side flowing out of the back-pressure chamber. However, this valve is primarily used for start-up. This ensures that a back pressure is formed right from the start.

According to the prior art, the back-pressure pressure is always formed by a so-called control flow from the high pressure (Pd) via the back-pressure space to the suction pressure (Ps). This control current represents a loss of compressor effectiveness, as it feeds already compressed gas back to the suction side and thus has a negative impact on the volumetric and isentropic efficiency of the machine. Furthermore, the control mass flow also represents an enthalpy flow. The control flow mixes with the inflowing suction gas on the suction side in front of the scroll unit, where it leads to an increase in temperature and a decrease in the density of the suction gas. This in turn has a negative impact on the volumetric mode of operation of the compressor.

Finally is out of the DE 10 2016 105 302 B4 a control flow control valve for scroll compressors is known, which for the invention generically at least consists of a housing and a closure element as well as fluid connections for the control flow, for the back pressure (Pb), for the high pressure (Pd) and for the suction pressure (Ps) with the effective areas assigned to the ports on the closure element. The control flow control valve also has a fluid connection for ambient pressure (PATM) with an assigned effective area on the closure element. This is designed in such a way that a resultant force from the pressures (Pd, Pb, Ps, PATM) applied to the closure element acts on the closure element in such a way that a control current flows from the high pressure (Pd) to the suction pressure (Ps), forming a counter-pressure (Pb). , wherein the ambient pressure (PATM) is designed to be fluid-tight with respect to the other spaces with high pressure (Pd), back pressure (Pb) and suction pressure (Ps) acting on the closure element.

While the foregoing prior art represents a significant improvement in several respects, the design changes set forth in the invention are intended to provide further improvements. For example, in order to bring the piston of the valve into the correct position, it is necessary to measure the pressures of the compressor and move the valve mechanism accordingly. To achieve this, the valve has two diaphragms with different pressure ranges on one side and the ambient pressure acting on the other side. In this way it is possible to measure the absolute values of the pressures and generate the necessary resultant force by choosing the appropriate area of the membrane.

Problematic aspects of this construction are the quality, robustness and tightness of the membranes. In the event of a malfunction of one of the diaphragms, the refrigerant system will leak and may lose its refrigerant charge, which can lead to a vehicle stall. Therefore, the requirements for the quality and reliability of the membrane are very high, which affects the unit price, quality and process control.

The object of the invention is to provide a control flow control valve which has a simple and robust design and, moreover, does not release any refrigerant into the environment in the event of an internal leak.

The task is solved by a control flow control valve with the features according to patent claim 1 . Further developments are specified in the dependent patent claims.

The object of the invention is achieved in particular by a control flow control valve for scroll compressors which, in terms of its basic structure, consists of at least one housing in which a closure element is arranged. Furthermore, fluid connections for the control flow, for the back pressure, for the high pressure and for the suction pressure are formed on the closure element with active surfaces assigned to the connections.

To seal off the low-pressure space from the back-pressure space, the closure element has exactly one ring-shaped diaphragm seal. This diaphragm seal holds and guides the closure element, with the low-pressure chamber being arranged on one side of the diaphragm seal with the retaining closure element and the counter-pressure chamber being arranged on the other side of the diaphragm seal. The low-pressure space and the back-pressure space are preferably circular-cylindrical and have a low-pressure space diameter, also known as the effective diameter of the low-pressure space, and a back-pressure space diameter, also known as the effective diameter of the back-pressure space.

The special feature of the control flow control valve according to the invention is that the construction of generic control flow control valves with several membranes is replaced by the construction according to the invention of the control flow control valve with a closure element with a single annular membrane which holds the closure element. According to the invention, the shape or the contour of the membrane seal is selected in such a way that the membrane seal has a definable, contour-dependent spring stiffness, which defines the force-displacement function of the closure element. The shape and contour of the membrane leads to wall support effects of the membrane, which can be quantified differently depending on the contour. This means that transfer functions for the valve can be set and dimensioned in advance by selecting the shape and contour of the diaphragm seal. In addition to the geometric conditions, the shape and contour of the membrane thus influences the effective diameter from the counter-pressure space to the low-pressure space, resulting in an effective effective diameter that is dependent on the membrane contour.

According to a particularly advantageous embodiment of the invention, the membrane seal is designed as a ring that surrounds the closure element. This ring has an outer contour in the shape of a truncated circle and an inner contour that is also in the shape of a truncated circle, the inner contour being filled by the closure element in the shape of a truncated circle. A conical shape of the membrane seal is visible in the longitudinal section and the membrane seal has a constant wall thickness over the height.

According to an alternative embodiment of the invention, the membrane seal is designed as a circular ring which has an outer contour and inner contour in the shape of a truncated cone. The inner contour is in turn frusto-conical Closing element filled. The conical shape of the membrane seal shown in the longitudinal section shows a decreasing wall thickness over the height.

According to a further advantageous embodiment of the invention, the diaphragm seal has a ring-like, circular-cylindrical outer contour and a truncated-cone-shaped inner contour, the inner contour being filled by the truncated-cone-shaped closure element. The membrane seal has an increasing wall thickness over the height.

A further alternative advantageous embodiment of the invention consists in a membrane seal for the control flow control valve, which has an S-shaped outer contour and an S-shaped inner contour of the same type, with the inner contour being filled by the closure element. The membrane seal has a constant wall thickness across the height.

The diaphragm seal of the control flow control valve is preferably formed from a flexible polymer such as ethylene propylene diene rubber (EPDM).

The membrane seal of the control flow control valve is preferably glued or galvanized to the border, or to the adjacent elements, so that there is a material-tight and pressure-tight connection.

The control flow control valve and in particular the diaphragm seal are designed for use with R744 as the fluid, since a preferred area of application for the control flow control valve is in refrigerant circuits with carbon dioxide as the refrigerant.

The membrane seal of the control flow control valve is designed and dimensioned for differential pressures of 20 bar to 40 bar.

The membrane seal of the control flow control valve is preferably designed for a differential pressure of 28 bar.

The concept of the invention is that the known two-membrane structure is replaced by a one-membrane design according to the invention in order to better meet the various requirements for functionality, robustness, manufacturability and costs.

The optimized membrane concept consists of a specially shaped membrane that offers the different pressure ranges. Due to the shape of the membrane, the resulting force is the same as when using two membranes with an ambient pressure connection.

As a result of the construction of the diaphragm seal according to the invention, the atmospheric access hole for the control flow valve becomes superfluous and in the event of a diaphragm failure there can now be no leakage to the outside, in contrast to the prior art.

The stress on the membrane is less due to the lower pressure differentials acting on it. The membrane consists of a flexible polymer that is glued or electroplated to the rigid environment. Any shape can be created in this way to meet surface area and force-to-displacement requirements.

• 1: Prinzipschaltbild eines Steuerstromregelventils mit radialer Umgebungsdruckbeaufschlagung nach dem Stand der Technik,
• 2: Detail Verschlusselement mit konischer Membrandichtung gleichbleibender Wandstärke,
• 3: Detail Verschlusselement mit konischer Membrandichtung abnehmender Wandstärke,
• 4: Detail Verschlusselement mit außen kreiszylindrischer und innen konischer Membrandichtung zunehmender Wandstärke und
• 5: Detail Verschlusselement mit außen konvexer und innen konkaver Membrandichtung gleichbleibender Wandstärke.

Further details, features and advantages of embodiments of the invention result from the following description of exemplary embodiments with reference to the associated drawings. Show it:

• 1 : Schematic diagram of a control flow control valve with radial ambient pressure application according to the prior art,
• 2 : Detail of closure element with conical membrane seal of constant wall thickness,
• 3 : Detail of closure element with conical membrane seal of decreasing wall thickness,
• 4 : Detail of closure element with membrane seal that is circular-cylindrical on the outside and conical on the inside, increasing wall thickness and
• 5 : Detail of the closure element with a membrane seal that is convex on the outside and concave on the inside and has the same wall thickness.

In 1 is a schematic diagram of a generic control flow control valve 1 with radial ambient pressure is shown. The control flow control valve 1 consists essentially of a housing 8 in which a closure element 9 is arranged so that it can move translationally from top to bottom, as shown.

The control flow control valve 1 according to the prior art has different connections 2, 3, 4 and 5. A flow path, which can be controlled by the closure element 9 , runs through the control flow control valve 1 . In the embodiment shown, a control flow from the high-pressure fluid connection 3 to the counter-pressure fluid connection 2 is regulated by the closure element 9 . Furthermore, a fluid connection suction pressure 4 and a fluid connection ambient pressure 5 are performed on the control flow control valve 1, the last said fluid connections do not form a flow path. Only the pressure levels of the suction pressure Ps and the ambient pressure ATM are transmitted to the effective surfaces of the closure element 9 via these fluid connections. At the same time, if there is a leak in the membrane seals 7, there is a risk that fluid will leak into the environment via the ambient pressure fluid connection 5, which is undesirable and should be avoided.

A spring 6 with a spring force F0 acts on the closure element 9 in the opposite direction to the closed position. The primary valve stem 111 is sealed with a sealing ring 10 . The geometric design of the closure element 9 is designed in such a way that the primary valve stem diameter d21, the sealing seat diameter d20, the effective diameter of suction pressure Ps to atmospheric pressure ATM d22 and the effective diameter of back pressure Pb to atmospheric pressure ATM d23 are dimensioned in such a way that a resultant force depending on the pressures applied the closure element 9 acts and thus controls the control flow from the high-pressure fluid connection 3 to the counter-pressure fluid connection 2 . According to the embodiment shown, the control flow control valve 1 also has a fluid connection, shown in dotted lines, from the fluid connection back pressure 2 to the space with the effective surface for the effective diameter back pressure Pb to atmospheric pressure ATM d23, in order to include the back pressure Pb accordingly in the balance of forces on the closure element 9.

In 2 is a detail of the control flow control valve 1 shown, which as well as the following 3 , 4 and 5 each shows the closure element 9 in its specific configuration according to the exemplary embodiments of the invention and the membrane seals 7 designed to correspond to the closure element 9.

Thus shows 2 schematically the low-pressure chamber 12 and indicated the spring element 6, which holds the closure element 9 in the lower position. The low-pressure space 12 is characterized geometrically by its circular-cylindrical cross-section and the effective diameter of the low-pressure space d24. According to the embodiment shown here, the closure element 9 is in the form of a truncated cone and is therefore shown as being conical in cross section. The shell of the circular truncated cone is correspondingly surrounded by the membrane seal 7, which according to the embodiment 2 is designed with a constant wall thickness over the height of the closure element 9 as a conically tapered circular cone ring. The membrane seal 7 is connected to the wall of the surrounding housing in a fluid-tight manner, preferably glued, galvanized or otherwise connected in a fluid-tight material and/or positive manner.

On the side of the control flow control valve 1 opposite the low-pressure chamber 12, the back-pressure chamber 11 is formed, which is characterized geometrically in its size and thus area ratios by the effective diameter of the back-pressure chamber d25.

The membrane seal 7 encloses the closure element 9 in the manner of a ring along the flank of the closure element 9 over the entire height.

In 3 the detail of the closure element 9 is formed with a conical membrane seal 7 with the special feature of the decreasing wall thickness from the side of the low-pressure space 12 to the side of the counter-pressure space 11 of the closure element 9 . Again, the spring element 6 and the geometric conditions and thus effective surfaces for pressure regulation of the effective diameter of the low-pressure chamber d24 and the effective diameter of the counter-pressure chamber d25 are shown schematically, each as an effective diameter.

In 4 differs from the exemplary embodiments 2 and 3 An embodiment of the invention is shown, which also has a conical closure element 9 in the shape of a truncated circular cone, but a membrane seal 7 is formed, which is characterized in that the wall thickness of the membrane seal 7 increases from the low-pressure chamber 12 to the counter-pressure chamber 11. In addition, the shape and contour of the diaphragm and the spring preload of the effective diameter of the low-pressure chamber d24 are greater than the effective diameter of the counter-pressure chamber d25.

In 5 Finally, an embodiment is shown which shows a closure element 9 with a spring element 6, which is constructed from two basic elements in the shape of a truncated circular cone which are arranged with their base sides facing one another. This results in a double cone shape, with the cone increasing from the ends towards the middle. The membrane seal 7 surrounds the double-cone-shaped closure element 9 and has an increasing wall thickness in the lower cone and a constant wall thickness in the upper cone of the ring. Due to these geometric variations and the additional wall support effects associated therewith, the effective diameters d25, d24 change from counter-pressure chamber 11 to low-pressure chamber 12 in relation to one another.

A further development of the invention that is not shown is that the closure element 9 and the membrane seal 7 have an s-shaped outer contour and inner contour, resulting in different wall support effects of the contour of the membrane and the corresponding contour of the wall of the housing and the closure element. This eventually leads to an effective effective diameter ratio.

Reference List

1

control flow control valve

2

Fluid connection back pressure

3

Fluid connection high pressure

4

Fluid connection suction pressure

5

Fluid connection Ambient pressure

6

spring element, spring

7

diaphragm seal

8th

Housing

9

closure element

10

sealing ring

11

back pressure space

12

low pressure room

111

primary valve stem

d20

seat diameter

d21

Primary valve stem diameter

d22

Pitch diameter Ps to ATM

d23

Pitch diameter Pb to ATM

d24

Effective diameter of the low-pressure chamber

d25

Effective diameter of back pressure chamber

F0

spring force

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• US20100158710A1 [0009]
• DE 102013021250 A1 [0010]
• US20100209819A1[0011]
• DE 102016105302 B4 [0014]

Claims (10)

Control flow control valve (1) for spiral compressors, consisting at least of a housing (8) and a closing element (9) as well as fluid connections (2, 3, 4) for the control flow, for the back pressure (Pb), for the high pressure (Pd) and for the Suction pressure (Ps) with the effective surfaces on the closure element (9) assigned to the connections, characterized in that the closure element (9) is used to seal off the low-pressure space (12) with an effective diameter of the low-pressure space (d24) and the back-pressure space (11) with an effective diameter of the back-pressure space (d25). has exactly one diaphragm seal (7) which is arranged on the closure element (9), the low-pressure chamber (12) being arranged on one side of the diaphragm seal (7) and the counter-pressure chamber (11) being arranged on the other side of the diaphragm seal (7), wherein the shape of the membrane seal (7) is selected in such a way that it has a definable, contour-dependent spring stiffness which defines the force-displacement function of the closure element (9). Control flow control valve (1) after claim 1 , characterized in that the membrane seal (7) has a ring-like outer contour and inner contour in the shape of a truncated circular cone, the inner contour being filled by the closure element (9) in the shape of a truncated circular cone and the conical shape of the membrane seal (7) in cross section having a constant wall thickness over the height. Control flow control valve (1) after claim 1 , characterized in that the membrane seal (7) has a ring-like outer contour and inner contour in the shape of a truncated circular cone, the inner contour being filled by the closure element (9) in the shape of a truncated circular cone and the conical shape of the membrane seal (7) in cross section having a decreasing wall thickness over the height. Control flow control valve (1) after claim 1 , characterized in that the diaphragm seal (7) has a ring-like, circular-cylindrical outer contour and a truncated circular inner contour, the inner contour being filled by the truncated circular closure element (9) and the diaphragm seal (7) having an increasing wall thickness over the height. Control flow control valve (1) after claim 1 , characterized in that the diaphragm seal (7) has an S-shaped outer contour and inner contour, the inner contour being filled by the closure element (9) and the diaphragm seal (7) having a constant wall thickness over the height. Control flow control valve (1) according to one of Claims 1 until 5 , characterized in that the diaphragm seal (7) is formed from a flexible polymer. Control flow control valve (1) according to one of Claims 1 until 6 , characterized in that the membrane seal (7) is glued to the rigid border. Control flow control valve (1) according to one of Claims 1 until 7 , characterized in that the diaphragm seal (7) is designed for use with R744 as the fluid. Control flow control valve (1) according to one of Claims 1 until 8th , characterized in that the membrane seal (7) is designed for differential pressures of 20 bar to 40 bar. Control flow control valve (1) after claim 9 , characterized in that the diaphragm seal (7) is designed for a differential pressure of 28 bar.

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