DE20114702U1 - Temperature control valve with a flow-controlling memory metal membrane - Google Patents

Description

Temperature control valve with a flow-controlling membrane made of Memory Metal

Applicant: ^1st Memory Alloys GmbH

Inventor: Prof. Dr. HG Steckmann, Dr. V. Prieb, Dr. LM Neganov

The invention relates to a temperature control valve for heating or cooling systems, for controlling the temperature of liquid or gaseous heating or cooling media, by changing the flow cross-section and thus the flow rate with the aid of a thermosensitive membrane made of a memory alloy, which reversibly effects the flow through its temperature-dependent shape changes between two positions "open and "closed".

Temperature control valves are well known and are used in various technical fields, such as heating, medical, automotive, plant engineering, etc. as thermostatic valves or as temperature control devices.

The task of such temperature control valves is to keep the temperature of the heating or cooling medium constant by changing the flow cross-section and, accordingly, the flow rate. This task has so far been solved by fulfilling three functions: the target-actual temperature difference measurement, the conversion of the measured value into a signal and the forwarding of this signal to a drive in the movement of the drive of a valve element that changes the flow. These functions are performed by various valve components, such as thermal sensors, signal converters or amplifiers, and drive mechanisms. This determines in advance the design and construction of various known temperature control valves.

DE 44 31 463 describes a compact controller for a control valve controlled by a pneumatic diaphragm actuator, in which a signal converter converts a temperature deviation detected by a thermal sensor into a pneumatic pressure signal for the diaphragm actuator. The diaphragm actuator actuates a valve tappet, which then changes the flow accordingly.

DE 43 36 914 describes a temperature control device, wherein the variable flow cross-sectional size of an expansion valve is controlled as a function of the temperature of a coolant measured by temperature sensors and thereby the temperature in the coolant circuit.

The two control systems described above are complicated and expensive and have a large number of components. In order to avoid the thermal sensors and the complex signal processing, a control valve is proposed in DE 198 55 926 in which two thermostats take over the functions of the thermal sensors and drives, so that the change in the length of the thermostats caused by the thermal expansion of the thermostat filling actuates a valve tappet through a transition piece and thus the flow of the heat transfer medium is changed.

This control valve also has a no less complicated design and a complex construction. In addition, the changes in length caused by thermal expansion and thus the valve tappet movements are too small to change the flow within wide limits.

The present invention is based on the object of presenting a temperature control valve of a simple construction, without thermal sensors, without signal processing and without drive mechanisms, in which all three functions are taken over by a single component, so that any temperature change of the heating or cooling medium leads to an immediate change in the flow cross-section or the flow rate and thus to the return of the temperature deviation.

This object is described according to the invention by the features of claims 1 to 6.

By installing a membrane made of a memory alloy in the valve body according to claim 1, which membrane has the two-way memory effect according to claim 4 and thereby reversibly changes its shape and accordingly the flow cross-section depending on the temperature, or according to claim 5 has the one-way memory effect, wherein the resetting of the change in shape of the memory membrane caused by the temperature change and the associated reversible change in the flow cross-section takes place by the opposing force of an elastic counter spring, a new,

A temperature control valve based on a new operating principle with a simple design that is inexpensive to manufacture and versatile in use.

The membrane, according to claim 2, made of a memory alloy with a narrow hysteresis, allows the temperature of the heating or cooling medium to be precisely regulated within a narrow temperature range.

The use, according to claim 3, of a multi-component memory alloy based on (Cu-Al) or (NiTi) makes it possible to adjust the transformation temperatures, as well as the hysteresis width and thus the control temperature and temperature bandwidth of the control valve by changing the composition with an accuracy of up to +/- 1°C in a temperature range from -200 ⁰ C up to 400 ⁰ C and thus to fulfill all possible areas of application of the control valve according to the invention.

The use of the two-way memory effect, according to claims 4 and 9, leads to a further simplification of the control valve construction.

The installation of an elastic counter spring, according to claims 5 and 10, reduces the flow rate difference between the "open" and "closed" states and reduces the temperature bandwidth of the control valve.

Cutting different opening profiles into the memory membrane, according to claim 6, expands the possibilities of varying the flow characteristics of the temperature control valve according to the invention, depending on the application requirements.

The design of the memory membrane or its opening flaps, according to claim 7, of a high-temperature form by plastic deformation at high temperatures and, according to claim 8, of a low-temperature form by martensitic deformation, allows, depending on the application requirements, the outlet opening of the temperature control valve according to the invention, as well as the

The flow rate difference between the inlet and outlet openings can vary, thereby further expanding the application range.

The deflection or deformation of the memory membrane, according to claim 12, against the flow direction of the heating or cooling medium, leads to a reduction in the flow rate and accordingly the flow quantity, and to the pressure of the heating or cooling medium flowing through being used as an additional force which supports the membrane closure when the temperature drops.

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The deflection or deformation of the memory membrane, according to claim 13, in the flow direction of the heating or cooling medium, leads to an additional increase in the flow velocity and accordingly to an increase in the flow rate.

Further details, features and advantages of the invention are shown in the following drawings and their description.

It is presented in :

Fig. 1a, b, c Temperature control valve for cooling systems with a two-way memory effect
trained memory membrane in the "closed" initial state (a) and in the "open" final state when installing the memory membrane in the flow direction (b) and in the opposite direction (c).

Fig. 2a, b, c Temperature control valve for cooling systems with an elastic

Counter spring and a memory membrane with the one-way memory effect in the "closed" initial state (a) and in the "open" final state when the memory membrane is installed in the flow direction (b) and in the opposite direction (c).

Fig. 3a, b The simplest low- (a) and high-temperature (b) forms of the memory membrane
without opening flaps.

Fig. 4 a, b The low- (a) and high-temperature form (b) of a memory membrane
with a round cut opening flap.

Fig. 5 a, b The low- (a) and high-temperature forms (b) of the memory membrane
with two rectangular cut opening flaps.

Fig. 6 a, b The low- (a) and high-temperature forms (b) of the memory membrane
with four diagonally cut opening flaps.

Fig. 7 a, b The low- (a) and high-temperature forms (b) of the memory membrane
with a spiral-shaped opening flap.

Fig. 8 Flow-temperature deviation diagram for the five in Fig. 3 to

Fig. 7 shown memory membranes (the curve number corresponds to the figure number described) in cooling systems (temperature deviation (T-TR)/ArTR)) and in heating systems (temperature deviation (TT _R )/Mf-T _R ))

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Fig. 9 Schematic deformation-temperature diagram of a memory

Membrane that characterizes the characteristic transition temperatures (M _s , Mf, As, Af) of the memory membrane and the resulting control temperature (Tr), the control accuracy (Δ=As-M _s ), and the temperature bandwidth (AT=Af-Mf) of the control valve.

A distinction is made between the one-way memory effect and the two-way memory effect. In the one-way memory effect, the shape of a memory metal piece imprinted by plastic deformation at high temperatures (high-temperature shape) is changed at temperatures below the finish temperature Mf of the martensitic transformation (Fig. 9) by the martensitic deformation under the effect of an external mechanical force (low-temperature shape). When the memory metal piece is heated beyond the temperature interval (A ₈ - A _f ) of the martensitic re-transformation (Fig. 9), the martensitic deformation is reversed and the memory metal piece returns to its original high-temperature shape. Further cooling beyond the temperature interval (M ₈ - Mf) does not lead to any further change in the shape of the memory metal piece. The maximum martensitic deformation that can be recovered with the one-way memory effect can be up to 7-8% for the known memory alloys.

With repeated one-way memory effect cycles, in which the memory metal piece is martensitic deformed again and again to the same low-temperature shape by a mechanical external force after each cooling, or when the thermal cycles are carried out on a memory metal piece loaded by a constant external force, the memory metal piece is trained to a two-way memory effect. With the two-way memory effect, the memory metal piece changes its shape spontaneously and reversibly between the low- and high-temperature shapes, during heating beyond the temperature interval (A ₈ - A _f ) and cooling down beyond the temperature interval (M ₈ - M _f ). The reversible martensitic deformation in the two-way memory effect is then only 2-3%.

If the recovery of the martensitic deformation is hindered by an external force Fh, a recovery force Fr develops on the part of the memory metal piece, which performs the work against the hindering external force and the

Recovery of the martensitic deformation under the condition Fh < Fr prevails. The recovery force is related to the martensitic yield point of ^m , which has a linear temperature dependence. For these reasons, the relationship between a constant external force F _H or load and the recovery force Fr(T) or the martensitic yield point σ? ^�Mgr; (�Tgr;) can change with temperature.

Figures 1a, 1b and 1c show the simplest embodiments of the temperature control valve according to the invention. The control valve consists of a valve body (1) which has an inlet and an outlet opening, and a memory membrane (2) trained for the two-way memory effect, which is attached to the body base (4) on one side with a screw (3). A conventional, commercially available transition piece for different pipe diameters can be used as the valve body, so that the temperature control valve according to the invention can be easily installed in any heating or cooling water line. The high-temperature shape of the memory membrane trained for the two-way memory effect is selected so that the control valve is opened to the maximum at higher temperatures (Fig. 1b and 1c). The low-temperature shape of the memory membrane, on the other hand, corresponds to the minimum control valve opening or its complete closure (Fig. 1a). This design is suitable for cooling systems. As long as the coolant remains at a control or cooling temperature T _R set by the composition of the memory alloy, the flow cross-section or flow rate of the coolant is minimal. If this flow rate is no longer sufficient for cooling and a temperature increase of 5/2=As-Tr occurs, the memory membrane begins to change shape to its high-temperature form, which leads to the valve opening and an increase in the flow rate of the coolant. If the temperature increase exceeds the value AT/2=Aj-Tr, the valve opening is at its maximum and can no longer change. After the increased flow rate of the coolant leads to a temperature drop above the value 6/2=T _R -M ₈ , the memory membrane begins to change shape back to its low-temperature form, which is completed at ÄT/2=Mf-TR. In this way, the control temperature T _R is kept in the range S=A ₈ -M ₈ determined by the control accuracy. The additional flow rate control of the coolant is achieved by installing the memory membrane in the flow direction (Fig. 1 b) or in the opposite direction (Fig. 1 c). When installed in the opposite direction, the opening memory

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Membrane offers greater resistance to the coolant flow and thus reduces the amount of coolant flowing through. In addition, the liquid pressure on the memory membrane installed in the opposite direction promotes the return to the low-temperature form when the temperature drops below the temperature M _s .

Figures 2a, 2b and 2c show a further embodiment of the temperature valve according to the invention, which also consists of a valve body (1), a memory membrane (2) having the one-way memory effect, which either sits freely on the body base (4) or can also be fastened with one or more screws (3), and an elastic counter spring (5). The counter spring (5) acts on the memory membrane with a force F _Hl which, when the temperature increases, is subject to the restoring force Fr (Fr>F _h ) and does not prevent the memory membrane from returning to its high-temperature form. When the temperature drops below the temperature M _s , the memory membrane transforms into the martensitic state without returning to its low-temperature form. Because the yield point of ^m becomes low at lower temperatures in the martensitic state, if the elastic spring force F _H exceeds this yield point, martensitic deformation takes place and the memory membrane is pressed or pulled back to its low-temperature shape by the counter spring. The installation of the memory membrane in the flow direction (Fig. 2 b) or in the opposite direction (Fig. 2 c) makes a contribution to the balance of forces and can be used accordingly.

Figures 3 to 7 show various embodiments of the memory membrane in the closed (a) and open (b) states. The memory membrane has various cut openings through which the flow cross-section or the flow rate is effectively changed, as shown by the flow-temperature deviation diagrams in Fig. 8.

Fig. 3 shows a simple embodiment of the memory membrane without opening flaps, already described with reference to Figs. 1 and 2, in which the entire memory membrane is deformed by bending and ensures the "opening-closing" of the control valve in the event of temperature changes (Fig. 8, line 3).

Fig. 4 shows an analogous embodiment in which a round opening flap is cut into the memory membrane, which is bent in the same way and functions in the same way as the entire memory membrane in Fig. 3. The opening of this opening flap (Fig. 4 b) or its closing (Fig. b) in the event of temperature changes

changes the flow cross-section or the flow rate parabolically depending on the temperature (Fig. 8, line 4). This embodiment is advantageous in that the maximum flow rate is determined by the diameter of the incision and not by the diameter of the outlet. The remaining ring of the memory membrane is used for better fastening, for example with several screws, of the memory membrane to the body base of the control valve, especially when installing the memory membrane without a counter spring in the opposite direction of flow.

Fig. 5 a, b shows a memory membrane with two rectangular opening flaps cut into it, the opening (Fig. 5 b) or closing (Fig. 5 b) of which changes the flow cross-section or the flow rate linearly with the temperature when the temperature changes (Fig. 8, line 5). The dimensions of the cut can also determine the flow rate.

Fig. 6 a, b shows a memory membrane with four incised triangular opening flaps, whose opening (Fig. 6 b) or closing (Fig. 6 b) parabolically changes the flow cross-section or the flow rate depending on the temperature (Fig. 8, line 6).

Fig. 7 a, b shows an embodiment of the memory membrane which is particularly suitable for low pressures and large flow rates, in which a spiral-shaped opening flap is cut, the opening (Fig. 7 b) or closing (Fig. 7 b) of which changes the flow cross-section or the flow rate exponentially with the temperature when the temperature changes (Fig. 8, line 7).

All memory membranes with the opening flaps shown in Fig. 4 to 7 are installed in the body (1) of the control valve according to the invention in the same way as shown in Fig. 1 and 2 for the memory membrane shown in Fig. 3 and they also function in the manner described above.

For heating systems, e.g. for an outlet temperature control valve of a radiator, the memory membrane is given its low-temperature shape at temperatures below the temperature M _s by the martensitic deformation, which opens the control valve when the temperature drops, and its high-temperature shape is given by the plastic deformation at high temperatures, which closes the control valve when the temperature rises. The memory membrane (2) is then installed in the body (1) of the control valve according to the invention in the manner described in

Fig. 2, where the counter spring (5) is used in such a way that it does not press the memory membrane back, as in cooling systems, but pulls it back upwards. The memory membrane is martensitic deformed by the elastic force of the counter spring, which leads to the opening of the control valve when the temperature drops, while the restoring force of the memory membrane exceeds the elastic force of the counter spring when the temperature rises, so that the memory membrane, or its opening flap, assumes its high-temperature shape and thus closes the control valve.

In Fig. 8, four lines of the flow-temperature diagram are shown, which characterize the opening flaps of the memory membrane shown in Figs. 4 to 7. Based on these flow-temperature characteristics, an embodiment suitable for a specific application can be selected. The diagram is the same both for cooling systems in which the temperature increase beyond the A ₈ -Ar temperature interval leads to the closing of the control valve, and for heating systems in which the temperature increase beyond the As-Ar temperature interval leads to the closing of the control valve.

Fig. 9 shows schematically the deformation or the reversible shape change of a memory membrane as a function of the temperature. The lines of the shape change during cooling and heating form a hysteresis, the spread of which MrAf determines the temperature bandwidth, the temperature Tr set to the middle of the temperature interval M ₈ -A ₈ determines the control temperature and the width of the temperature interval O=A ₈ -M ₈₁ the control accuracy of the control valve. The temperatures M ₈ , A ₈ are characteristic starting temperatures and Mf, Af correspond to the finishing temperatures of the martensitic forward (M) and reverse transformation (A). These characteristic temperatures can be adjusted by varying the composition of the memory alloy.

Claims (13)

1. Temperature control valve with a flow-controlling membrane made of a memory alloy or memory membrane ( 2 ) built into the body ( 1 ) of the temperature control valve, which influences the flow cross-section of the temperature control valve and thus the flow rate of the heating or cooling medium through its temperature-dependent deformation ( Fig. 1a, b, c; 2a, b, c). 2. Temperature control valve according to claim 1, characterized in that the memory membrane ( 2 ) is made of a memory alloy with a narrow hysteresis, so that the temperature difference between the starting temperatures of the martensitic reverse transformation A _S , at which the increase in the flow cross-section begins during a temperature increase, and the forward transformation M _S , at which the reduction in the flow cross-section begins during a temperature decrease, is less than 5°C ( Fig. 9). 3. Temperature control valve according to claims 1 and 2, characterized in that the memory alloy is a multi-component alloy based on (Cu-Al) or (NiTi) and the control temperature T _R , as well as the temperature bandwidth M _r -A _f , ( Fig. 9) of the control valve can be adjusted by the composition of the memory alloy. 4. Temperature control valve according to claim 1, characterized in that the memory membrane ( 2 ) has the two-way memory effect and influences the flow cross-section and thus the flow rate of the heating or cooling medium through the temperature-dependent reversible movements between two cold and hot end shapes impressed on it ( Fig. 1a, b). 5. Temperature control valve according to claim 1, characterized in that the memory membrane ( 2 ) has the one-way memory effect, deforms to the high-temperature shape impressed on it when the temperature of the heating or cooling medium increases, and is deformed back to its original low-temperature shape by the force of a counter spring ( 5 ) when the temperature decreases, so that the flow cross-section and thus the flow rate of the heating or cooling medium is influenced by these changes in shape ( Fig. 2a, b). 6. Temperature control valve according to claims 1 and 4, 5, characterized in that different opening profiles or opening flaps are cut into the memory membrane ( 2 ) ( Fig. 4-7), which cause different flow temperature characteristics of the control valve ( Fig. 8). 7. Temperature control valve according to claims 1 to 6, characterized in that the memory membrane ( 2 ) or its opening flaps are impressed with a high-temperature shape by the plastic deformation at temperatures of 700 to 800°C, which is created when heated and leads either in cooling systems to an increase in the flow cross-section ( Fig. 1b, 2b), i.e. to valve opening, or in heating systems to a reduction in the flow cross-section, i.e. to valve closing ( Fig. 2a). 8. Temperature control valve according to claims 1 to 7, characterized in that the memory membrane ( 2 ) is installed in the valve body in a shape or shape of its opening flaps which is changed at lower temperatures by martensitic deformation, which either cause a minimum flow cross-section ( Fig. 1a, 2a) in cooling systems or a maximum flow cross-section ( Fig. 2b) in heating systems. 9. Temperature control valve according to claims 1 to 4 and 6, characterized in that the memory membrane ( 2 ) or its opening flaps are trained in the two-way memory effect by repeated thermal cycles with the change in shape at lower temperatures according to claim 7 and it is then installed in the valve body ( 1 ) according to claim 8 ( Fig. 1a, b, c). 10. Temperature control valve according to claims 1 to 3 and 5 to 8, characterized in that an elastic counter spring ( 5 ) is inserted into the valve body ( 2 ) ( Fig. 2a, b, c), the force of which counteracts the restoring force of the memory membrane ( 2 ) which changes its shape when heated, without being able to prevent the change in shape, but promotes the martensitic deformation of the memory membrane ( 2 ) or of the opening flap cut into the memory membrane ( 2 ) to its low-temperature shape when the temperature drops ( Fig. 2a, b, c). 11. Temperature control valve according to claims 1 and 4 to 10, characterized in that the memory membrane ( 2 ) is fastened to the bottom ( 4 ) of the valve body ( 1 ) with one or more screws ( 3 ) ( Fig. 1, 2). 12. Temperature control valve according to claims 1 and 4 to 11, characterized in that the memory membrane ( 2 ) is installed in the valve body ( 1 ) in such a way that its change in shape or the change in shape of its opening flap occurs in the flow direction of the heating or cooling medium when the temperature rises ( Fig. 1b and 2b). 13. Temperature control valve according to claims 1 and 4 to 11, characterized in that the memory membrane ( 2 ) is installed in the valve body ( 1 ) in such a way that its change in shape or the change in shape of its opening flap occurs against the flow direction of the heating or cooling medium when the temperature rises ( Fig. 1c and 2c).