GB2566961A - Valve subassembly - Google Patents

Abstract

A valve subassembly VSA1, VSA2 of a valve PV for controlling a fluid flow into and out of a fluid cell FC comprises a valve subassembly housing H1, H2 including a pressure chamber PC1, PC2 and fluid ports FP1, FP2 opening into the pressure chamber PC1, PC2. Valve subassembly caps C1, C2 are arranged inside the pressure chamber PC1, PC2 and are movable along a lift axis LA between open and closed positions for respectively opening and closing the fluid ports FP1, FP2. At least one shape memory alloy (SMA) wire SMA11, SMA12, SMA21, SMA22 is coupled to the valve subassembly housing H1, H2 and to the valve subassembly caps C1, C2. Upon applying electric power to the SMA wire the length of the SMA wire changes and causes the valve subassembly caps C1, C2 to move between the open and closed positions. The SMA wire includes a bent section (BS, Figs. 3, 4) extending along a longitudinal direction (LD, Figs. 3, 4) parallel to the lift axis LA, and the bent section BS includes at least one bent portion BP extending perpendicular to the longitudinal direction LD.

Description

(57) A valve subassembly VSA1, VSA2 of a valve PV for controlling a fluid flow into and out of a fluid cell FC comprises a valve subassembly housing H1, H2 including a pressure chamber PC1, PC2 and fluid ports FP1, FP2 opening into the pressure chamber PC1, PC2. Valve subassembly caps C1, C2 are arranged inside the pressure chamber PC1, PC2 and are movable along a lift axis LA between open and closed positions for respectively opening and closing the fluid ports FP1, FP2. At least one shape memory alloy (SMA) wire SMA11, SMA12, SMA21, SMA22 is coupled to the valve subassembly housing H1, H2 and to the valve subassembly caps C1, C2. Upon applying electric power to the SMA wire the length of the SMA wire changes and causes the valve subassembly caps C1, C2 to move between the open and closed positions. The SMA wire includes a bent section (BS, Figs. 3, 4) extending along a longitudinal direction (LD, Figs. 3, 4) parallel to the lift axis LA, and the bent section BS includes at least one bent portion BP extending perpendicular to the longitudinal direction LD.

S2

FIG 2

VSA1 VSA2

3/6

FIG 3

FIG 4

L

lO ω

cP cP ίΖ

6/6

Description

Valve subassembly

The present invention relates to a valve subassembly of a valve, in particular of a pneumatic valve, for controlling a fluid flow into and out of a fluid cell. The present invention further relates to a valve for controlling a fluid flow into and out of a fluid cell as well as to a valve arrangement. The valve subassembly, the valve and the valve arrangement can be used in particular in a seat adjustment device for adjusting a contour of a seating face of a vehicle seat.

In modern vehicle seats, there are fluid cells or chambers which are inflated by pressurized fluid to adjust a sitting face or a backrest face of the vehicle seat (together termed seating face of the vehicle seat) . These fluid cells are operated by valves which control a fluid flow into and out of the fluid cell. The valves can be actuated by using a valve actuator. One example of such a valve actuator is a so-called shape memory alloy element herein after also called SMA element.

A SMA element is a metal alloy element which, dependent on its temperature, presents itself in two different states. At a first temperature, typically at ambient temperature, the SMA element presents itself in a first state, for example in a state in which the SMA wire includes a predetermined first length. Once the temperature of the SMA element exceeds a predetermined threshold temperature, typically in the range between 80°C and 100°C, the SMA element presents itself in a second state, for example in a state in which the SMA wire includes a second length smaller than the first length. When the temperature of the SMA element falls again below the threshold temperature, the SMA elements reverts to the first state and, for example, retains its original first length.

The change of length of the SMA element between first and second lengths can be used to actuate a valve element.

In valves, these SMA elements are often used as wires coupled to the valve element. Electric power is applied to the SMA element and - as the SMA element is coupled to the valve element - the change of length of the SMA element causes the valve element to move between an open position and a closed position.

One particular problem with the use of these SMA elements in valves, and in particular in pneumatic valves, is however that for a given SMA element, the change of length of the SMA element is limited. As a result, there may only be an insufficient amount of fluid flowing through the valve.

It is thus an object of the present invention to provide a valve subassembly, a valve and a valve arrangement which overcomes the above problem.

The object is solved by the subject-matters of the independent claims. Further developments are given in the dependent claims.

According to a first aspect of the invention, a valve subassembly of a valve configured to control a fluid flow into and out of a fluid cell is provided. The valve subassembly comprises a valve subassembly housing including a pressure chamber and a fluid port opening into the pressure chamber. The valve subassembly further comprises a valve subassembly cap arranged inside the pressure chamber and being moveable along a lift axis between an open position for opening the fluid port and a closed position for closing the fluid port. The valve subassembly further comprises at least one shape memory alloy wire (herein after also called SMA wire) being coupled to the valve subassembly housing and the valve subassembly cap. The at least one shape memory alloy wire is configured to change its length in dependence of electric power, in particular electric current, applied to the at least one shape memory alloy wire such that, upon applying electric power to the at least one shape memory alloy wire, the length of the at least one shape memory alloy wire changes and causes the valve subassembly cap to move between the open position and the closed position. The at least one shape memory alloy wire further includes a bent section extending along a longitudinal direction extending itself parallel to the lift axis wherein the bent section includes at least one bent portion extending perpendicular to the longitudinal direction.

By using a SMA wire with a bent portion extending perpendicular to the longitudinal direction, for a given installation space of the SMA wire, the change of length of the SMA wire can be increased. As a result, a lift distance of the valve subassembly cap can be increased allowing for a larger flow rate of fluid through the valve.

According to an embodiment of the valve subassembly, the at least one shape memory alloy wire extends along a wire axis extending itself substantially parallel to the longitudinal direction. As the SMA wire extends along a wire axis extending itself substantially parallel to the longitudinal direction, the change of length of the SMA wire can be effectively increased. Moreover, as the longitudinal direction extends itself substantially parallel to the lift axis, the change of length of the SMA wire is in the direction of the lift axis and thus an optimized force transmission between the SMA wire and the valve subassembly cap is provided.

According to another embodiment, the bent section extends substantially about the entire length of the shape memory alloy wire, that is except for the ends of the SMA wire. As the bent section extends substantially about the entire length of the SMA wire, a change of length of the SMA wire can be maximized for a given length of the SMA wire and therewith a lift distance of the valve subassembly cap can be maximized.

According to another embodiment, the bent section at least partially includes a helical shape. Within the meaning of this disclosure, the term helical shape describes the shape of a SMA wire winding itself about a single axis wherein each turn or winding of the SMA wire has the same pitch. The pitch is the height of the turn measured parallel to the axis of the helix.

According to a preferable embodiment, the helical shape is a circular helix. In a circular helix, the turns of the SMA wire have the same diameter. As a result, the turns of the SMA wire have a constant curvature and the SMA wire is subjected to a constant torsion during the change of length of the SMA wire. This leads to a uniform change of length of the SMA wire and allows a more accurate actuation of the SMA wire compared to a SMA wire having a non-circular helix.

According to another embodiment, the bent section at least partially includes a meander shape. In this embodiment, the bent section includes a substantially two-dimensional shape compared to the three-dimensional shape of the helical shape. Also the meander shape includes a bent portion extending perpendicular to the longitudinal direction. The meander shape therefore also allows an increased change of length of the SMA wire.

According to another embodiment, the at least one shape memory alloy wire includes a first straight end coupled to the valve subassembly cap and a second straight end coupled to the valve subassembly housing. As the at least one SMA wire is coupled to the valve subassembly cap and the valve subassembly housing by straight ends, during a change of length of the SMA wire, no bending of the end of the SMA wire occurs. As a result, there is no friction between the ends of the SMA wire and the valve subassembly cap and the valve subassembly housing. Thus, the lifetime of the SMA wire can be increased.

According to another embodiment of the valve subassembly, the valve subassembly further comprises a biasing member for biasing the valve subassembly cap towards the open position or the closed position. The biasing member functions as a resetting member which causes the valve subassembly cap to move the valve cap assembly cap towards one of the open or closed positions when the SMA wire is not actuated. Preferably, the biasing member is configured such that the valve subassembly cap is biased towards a closed position. In this preferable embodiment, a normally closed valve is provided where upon applying electric power to the SMA wire the change of length of the SMA wire causes the valve subassembly cap to open against the biasing force of the biasing member .

According to another embodiment, the at least one shape memory alloy wire comprises two shape memory alloy wires wherein each shape memory alloy wire is coupled to the valve subassembly housing and to the valve subassembly cap and wherein each shape memory alloy wire includes the bent section. By using two SMA wires instead of one SMA wire, each SMA wire has to provide only half of the lifting force for the valve subassembly cap. As a result, a smaller diameter SMA wire can be chosen which reduces costs and allows a faster cooling of the SMA wire.

According to a preferred embodiment, a first shape memory alloy wire of the two shape memory alloy wires extends itself along a first wire axis and a second shape memory alloy wire of the two shape memory wires extends itself along a second wire axis, and the lift axis, the first wire axis and the second wire axis are all arranged in a common plane. In this embodiment, as the lift axis, the first wire axis and the second wire axis are all arranged in a common plane, during lifting of the valve subassembly cap, no tilting or bending of the valve subassembly cap occurs and a more accurate control of the valve subassembly cap is possible.

According to another embodiment, the valve subassembly cap includes a piston member and a sealing member connected to the piston member, wherein the piston member and/or the sealing member include a heat insulating material. In this embodiment, as the piston member and/or the sealing member include a heat insulating material, a heat dissipation from the SMA wire to the piston member and/or the sealing member can be minimized. As a result, effects on cooling of the SMA wire can be reduced and a control of the SMA wire can be improved. In a preferable embodiment, the heat insulating material is a plastic material.

According to a second aspect of the present invention, a valve for controlling a fluid flow into and out of a fluid cell is provided. The valve comprises a first valve subassembly according to the first aspect and its embodiments and a second valve subassembly according to the first aspect and its embodiments. The valve also comprises a connection passage configured to fluidly connect the pressure chamber of the first valve subassembly to the fluid port of the second valve subassembly. In this embodiment, two valve subassemblies are combined to form a valve .

According to an embodiment of the valve, the valve is configured to be used in a seat adjustment device of a vehicle seat for adjusting a contour of a seating face of the vehicle seat.

According to a third aspect of the present invention, a valve arrangement is provided. The valve arrangement comprises a first valve according to the second aspect and its embodiment, wherein the first valve includes a fluid supply conduit with a fluid supply conduit inlet and a fluid supply conduit outlet. The valve arrangement further comprises a second valve according to the second aspect and its embodiment, wherein the second valve includes a fluid supply conduit with a fluid supply conduit inlet and a fluid supply conduit outlet. The valve arrangement further comprises a valve connection conduit fluidly connecting the fluid supply conduit outlet of the first valve with the fluid supply conduit inlet of the second valve.

By combining two (or more) valves to a valve arrangement, individual control over a plurality of fluid cells is possible.

Exemplary embodiments of the invention are described by the accompanying drawings, which are incorporated herein and constitute a part of the specification. In the drawings:

Fig. 1 is a schematic view of an exemplary embodiment of a valve including two valve subassemblies according to an exemplary embodiment of the present invention;

Fig. 2 is a cross-sectional view through the valve of Fig.

1;

Fig. 3 is a detailed schematic view of an embodiment of a shape memory alloy wire including one example of a bent section;

Fig. 4 is a detailed schematic view of another embodiment of a shape memory alloy wire including another example of a bent section;

Fig. 5 is a three-dimensional view of the valve of Fig. 1 connected to a printed circuit board;

Fig. 6 is a schematic view of a valve arrangement including two valves according to an embodiment of the invention; and

Fig. 7 is a schematic view of another embodiment of a valve including two valve subassemblies according to another embodiment of the present invention.

Fig. 1 shows a schematic view of an embodiment of a valve PV. Valve PV includes a first valve subassembly VSA1 and a second valve subassembly VSA2 . Valve PV is configured to control a fluid flow into and out of a fluid cell FC (indicated schematically by the dashed line). For example, valve PV is a pneumatic valve configured to control a fluid flow into and out of a fluid cell FC of a seat adjustment device of a vehicle seat VS for adjusting a contour C of a seating face SF of vehicle seat VS.

As can be seen in Fig. 1, first valve subassembly VSA1 and second valve subassembly VSA2 have the same design. Thus, a detailed explanation of first valve subassembly VSA1 is provided first, followed by a much shorter description of second valve subassembly VSA2 .

First valve subassembly VSA1 includes a valve subassembly housing Hl. Valve sub assembly housing Hl includes a pressure chamber PCI for accommodating pressurized fluid. Valve subassembly housing Hl further includes a fluid port FP1 opening into pressure chamber

PCI to provide pressurized fluid to pressure chamber PCI. Valve subassembly housing Hl also includes a fluid outlet FO1 opening into pressure chamber PCI for providing pressurized fluid to fluid cell FC.

Valve subassembly VSA1 further includes a valve subassembly cap Cl arranged inside pressure chamber PCI and moveable along a lift axis LA between an open position for opening fluid port FP1 and a closed position for closing fluid port FP1.

Valve subassembly VSA1 further includes two shape memory alloy wires (SMA wires) SMA11, SMA12. SMA wires SMA11, SMA12 are configured to change their lengths in dependence of an electric power, particularly electric current, applied to SMA wires SMA11, SMA12. SMA wires SMA11, SMA12 each include a first end El and a second end E2 opposite first end El. First ends El are connected to a sealing member SMI of valve subassembly cap Cl. Sealing member SM 1 is configured to seal fluid port FP1 in the closed position of valve subassembly cap Cl. Second ends E2 of SMA wires SMA11, SMA12 are connected to electric pins Pll, P12. Electric pins Pll, P12 are connected to connection elements CE11, CE12 which, in turn, are connected to valve subassembly housing Hl. Hence, second ends E2 of SMA wires SMA11, SMA12 are coupled to valve subassembly housing Hl via electric pins Pll, P12 and connection elements CE11, CE12.

Electric pins Pll, P12 are used to provide electric power to SMA wires SMA11, SMA12 for actuating SMA wires SMA11, SMA12. Upon applying electric power to SMA wires SMA11, SMA12, the length of SMA wires SMA11, SMA12 changes so that valve subassembly cap Cl is moved between the open position and the closed position.

As can be seen in Fig. 1, first ends El and second ends E2 are configured as straight ends, i.e. first and second ends El, E2 are free of any bendings. Thus, first ends El and second ends E2 are coupled to valve subassembly cap Cl and valve subassembly housing Hl, respectively, without any bendings. As first ends El and second ends E2 are coupled to valve subassembly cap Cl and valve subassembly housing Hl without any bendings, upon applying electric power to the SMA wires SMA11, SMA12, a change of length of the SMA wires SMA11, SMA12 does not cause a bending of first ends El or second ends E2 . As a result, substantially no friction between first ends El and valve subassembly cap Cl and substantially no friction between second ends El and valve subassembly housing Hl occurs and the lifetime of SMA wires SMA11, SMA12 can be improved.

Valve subassembly VS1 further includes a biasing member BM1. Biasing member BM1 is connected to sealing member SMI and coupled to valve subassembly housing Hl via connection elements CE11, CE12. Biasing member BM1 is configured to bias valve subassembly cap Cl towards the closed position such that sealing member SMI can sealingly close fluid port 1. Biasing member BM1 may be, for example, a metal spring. In other embodiments, biasing member BM1 may bias valve subassembly cap Cl towards the open position.

As can be further seen in Fig. 1, biasing member BM1 and sealing member SMI are aligned on lift axis LA. Moreover, SMA wire SMA11 extends along a first wire axis WAI with first end El and second end E2 being arranged on first wire axis WAI, and SMA wire SMA12 extends along a second wire axis WA2 with first end El and second end E2 being arranged on second wire axis WA2.

As can be seen, first wire axis WAI and second wire axis WA2 each extend substantially parallel to lift axis LA. As first wire axis WAI and second wire axis WA2 each extend substantially parallel to lift axis LA, the change of length of SMA wires SMA11, SMA12 occurs in the direction of lift axis LA. As a result, a lift force generated by a change of length of SMA wire SMA11, SMA12 can be optimally transmitted from SMA wires SMA11, SMA12 to sealing member SMI of valve subassembly cap Cl. This allows for an optimized force transmission from SMA wire SMA11, SMA12 to valve subassembly cap Cl.

Moreover, as can be seen in Fig. 1, first wire axis WAI and second wire axis WA2 are all arranged in a common plane P. As lift axis LA, first wire axis WAI and second wire axis WA2 are all arranged in common plane P, during lifting of valve subassembly cap Cl, no tilting or bending of valve subassembly cap Cl occurs. As a result, a more accurate control of valve subassembly cap 1 is possible and a more reliable sealing of fluid port FP1 is achievable .

Referring now briefly to second valve subassembly VSA2.

As mentioned, second valve subassembly VSA2 has the same design as first valve subassembly VSA1. That is, second valve subassembly VSA2 includes a valve subassembly housing H2 having a pressure chamber PC2 with a fluid port FP2 opening into pressure chamber PC2. Valve subassembly housing H2 also includes a fluid outlet F02. Fluid outlet FO2 is connected to the ambience for allowing fluid to be discharged from pressure chamber 2.

As with first valve subassembly VSA1, second valve subassembly VSA2 includes a valve subassembly cap C2 which is arranged inside pressure chamber PC2 . Valve subassembly cap C2 is moveable along lift axis LA of valve subassembly cap Cl, i.e. along the same axis, between an open position and a closed position for opening and closing fluid port FP2.

As with first valve subassembly VSA1, second valve subassembly VSA2 includes two SMA wires SMA21, SMA22 which are each configured to change their lengths in dependence of electric power, in particular electric current applied to SMA wires SMA21, SMA22, so that valve subassembly cap C2 is moved between the open position and the closed position. SMA wires SMA21, SMA22 each include a first end El and a second end E2 opposite first end El. First ends El are connected to a sealing member SM2 of second valve subassembly cap Cl for sealing fluid port FP2 in the closed position of valve subassembly cap C2 . Second ends E2 of SMA wires SMA21, SMA22 are connected to electric pins P21, P22 which, in turn, are connected to connection elements CE21, CE22 to couple SMA wires SMA21, SMA22 to valve subassembly housing H2.

As with first valve subassembly VSA1, first ends El and second ends E2 of SMA wires SMA21, SMA22 are configured as straight ends so that a change of length of SMA wires SMA21, SMA22 does not cause a bending of first and second ends El, E2.

In addition, as with first valve subassembly VSA1, SMA wire SMA21 extends along first wire axis WAI and SMA wire SMA22 extends along second wire axis WA2 . Thus, SMA wires SMA11, SMA21 extend along the same wire axis WAI and SMA wires SMA21, SMA22 extend along the same wire axis WA2.

As with first valve subassembly VSA1, first wire axis WAI of SMA wire SMA21 and second wire axis WA2 of SMA wire SMA22 each extend substantially parallel to lift axis LA to optimize a force transmission from SMA wires SMA21, SMA22 to valve subassembly cap C2. Moreover, as with first valve subassembly VSA1, first wire axis WAI, second wire axis WA2 and lift axis LA are all arranged in a common plane P to prevent any tilting or bending of valve subassembly cap C2.

As with first valve subassembly cap Cl, second valve subassembly cap C2 also includes a biasing member BM2 connected to sealing member SM2 and coupled to valve subassembly housing H2 via connection elements CE21, CE22. Biasing member BM2 is configured to bias valve subassembly cap C2 towards the closed position such that sealing member SM2 can sealingly close fluid port FP2.

As can be further seen in Fig. 1, valve PV further includes a fluid supply conduit FSC. Fluid supply conduit FSC is arranged in pressure chamber PCI of first valve subassembly VSA1 and configured to provide pressurized fluid, such as pressurized air, to pressure chamber PCI. Fluid supply conduit FSC includes a fluid supply conduit inlet FSCI and a fluid supply conduit outlet FSCO opposite fluid supply conduit inlet FSCI. Fluid supply conduit FSC is further fluidly connected to fluid port FP1 of first valve subassembly VSA1 so that in an open position of valve subassembly cap Cl pressurized fluid can enter pressure chamber PCI via fluid port FP1.

Referring now to Fig. 2, a cross-sectional view through valve PV of Fig. 1 is shown. Elements already explained in connection with Fig. 1 such as fluid ports FP1, FP2 have the same reference numerals .

As can be seen in Fig. 2, valve PV includes a connection passage CP fluidly connecting pressure chamber PCI of first valve subassembly VSA1 to fluid port FP2 of second valve subassembly VSA2 . By providing connection passage CP, a fluid communication between pressure chamber PCI of first valve subassembly VSA1 and pressure chamber PC2 of second valve subassembly VSA2 is provided. This allows pressurized fluid to flow from pressure chamber PCI to pressure chamber PC2

Referring now to Fig. 3, a detailed schematic view of an embodiment of SMA wires SMA11, SMA12, SMA21, SMA22 used in valve

PV of Fig. 1 is shown. For clarity, this embodiment is referred to in the following by SMA wire SMA3.

SMA wire SMA3 includes first end El and second E2 arranged on common wire axis WA. SMA wire SMA3 further includes a bent section BS . Bent section BS extends substantially about the entire length L (except for first and second ends El, E2) of SMA wire SMA3 . Bent section BS extends along a longitudinal direction LD which extends itself parallel to lift axis LA and wire axis WA. Bent section BS further includes at least one bent portion BP which extends itself perpendicular to longitudinal direction LD. As a result, for a given length L of SMA wire SMA3 (measured between first and second ends El, E2, as shown), bent section BS allows for a larger change of length of SMA wire SMA3 compared to a SMA wire having the same length L but no bent section. By increasing the change of length of SMA wire SMA3 using bent section BS, a lift distance of valve subassembly caps Cl, C2 for a given installation space of SMA wire SMA3 can be increased and a higher fluid flow through valve PV is possible.

In the particular embodiment shown in Fig. 3, bent section BS includes a helical shape HS . In the particular embodiment shown, helical shape HS is a circular helix including three complete turns Tl, T2, T3, each having a diameter D and a pitch P. As each turn Tl, T2, T3 includes the same diameter D and the same pitch P, SMA wire SMA3 has a constant curvature in bent section BS and thus is subjected to a constant torsion once SMA wire SMA3 changes its length. The constant curvature and the constant torsion within bent section BS leads to a uniform change of length of SMA wire SMA3 within bent section BS and therefore provides a more accurate control over the change of length of SMA wire SMA3.

In other embodiments, the circular helix HS may include more or less than three complete turns. Also, helical shape HS may not be a circular helix but a conical helix with a tapered shape depending on the installation space provided for SMA wire SMA3 .

Referring now to Fig. 4, a detailed schematic view of another embodiment of SMA wires SMA11, SMA12, SMA21, SMA22 used in valve PV of Fig. 1 is shown. For clarity, this embodiment is referred to in the following by SMA wire SMA4.

Compared to the embodiment shown in Fig. 3, SMA wire SMA4 includes a bent section BS extending itself along longitudinal direction LD and having a meander shape MS. Compared to the three-dimensional helical shape HS of Fig. 3, the meander shape MS of Fig. 4 is a two-dimensional shape which also includes at least one bent portion BP extending perpendicular to longitudinal direction LD. Thus, also by using a meander shape MS, SMA wire SMA4 allows for an increased change of length for a given installation space of SMA wire SMA4.

It is conceivable that in further embodiments, the bent section BS includes both a helical shape HS and a meander shape MS.

It is also conceivable that SMA wires SMA11, SMA12, SMA21, SMA22 may have a bent section BS with other shapes than the mentioned helical shape HS or meander shape MS as long as the bent section BS includes at least one bent portion BP extending perpendicular to the longitudinal direction LD of the bent section BS.

Referring now to Fig. 5, a three-dimensional view of valve PV of Fig. 1 is shown. As can be seen, valve subassembly housing Hl of first valve subassembly VSA1 and valve subassembly housing H2 of second valve subassembly VSA2 are combined to a common valve housing H.

As can be further seen, valve PV includes fluid supply conduit FSC and the already mentioned fluid outlets FO1 and FO2 of first valve subassembly VSA1 and second valve subassembly VSA2, respectively. Valve housing H of valve PV is further connected to a printed circuit board PCB. Printed circuit board PCB is sealingly connected to common valve housing H via a sealing member S (see Fig. 1). Printed circuit board PCB is further configured to electrically connect electrical pins Pll, P12, P21, P22 of SMA wires SMA11, SMA12, SMA21, SMA22 so that electric power can be applied to SMA wires SMA11, SMA12, SMA21, SMA22 for actuating valve subassembly caps Cl, C2.

Referring now to Fig. 6, a valve arrangement VA combining two valves according to an exemplary embodiment discussed in connection with Figs. 1 to 5 is shown. Valve arrangement VA includes a first valve PV1 and a second valve PV2. Valve arrangement VA further includes a valve connection conduit VCC which fluidly connects fluid supply conduit outlet FSCO of first valve PV1 with fluid supply conduit inlet FSCI of second valve PV2 . Due to the design of first and second valves PV1, PV2 it is possible that first valve PV1 can control a fluid flow into and out of a first fluid cell FC1 and that second valve PV2 can control a fluid flow into and out of a second fluid cell FC2 individually. As can be seen in Fig. 6, first valve PV1 includes a first printed circuit board PCB1 and second valve PV2 includes a second printed circuit board PCB2. In other embodiments, first valve PV1 and second valve PV2, may however be arranged on a common printed circuit board.

Referring now to Fig. 7, another embodiment of a valve PV3 is shown. Valve PV3 includes a first valve subassembly VSA1 with a valve subassembly cap C3 and a second valve subassembly VSA2 with a valve subassembly cap C4. Compared to valve subassembly caps Cl, C2 of valves PV, PV1, PV2 explained in connection with Figs.

to 6, valve subassembly caps C3, C4 of Fig. 7 each include a piston member PM1, PM2. One end of piston member PM1, PM2 is connected to sealing member SMI, SM2. The other end of piston member PM1, PM2 is connected to biasing member BM1, BM2 and movably guided within biasing member BM1, BM2 which has the shape of a bent spring.

In the particular embodiment shown in Fig. 7, piston member PM1, PM2 and/or sealing member SMI, SM2 include or are made of a heat insulating material such as a plastic material. As piston member PM1, PM2 and/or sealing member SMI, SM2 include or are made of a heat insulating material, a heat dissipation from SMA wire SMA11, SMA12, SMA21, SMA22 to piston member PM1, PM2 and/or sealing member SMI, SM2 can be minimized. As a result, effects on cooling of SMA wires SMA11, SMA12, SMA21, SMA22 can be reduced and a control of SMA wires SMA11, SMA12, SMA21, SMA22 can be improved.

In the following, operation of valves PV, PV1, PV2, PV3 is briefly described.

As mentioned, valves PV, PV1, PV2, PV3 include a first valve subassembly VSA1 and a second valve subassembly VSA2 . First valve subassembly VSA1 includes pressure chamber PCI and second valve subassembly VSA2 includes pressure chamber PC2. Both pressure chambers PCI, PC2 are fluidly connected via connection passage CP (see Fig. 2). Pressure chamber PCI further includes fluid outlet FO1 and pressure chamber PC2 further includes fluid outlet FO2. In order to explain the operation of valves PV, PV1, PV2, PV3, in the following, it is assumed that fluid outlet FO2 is connected to the ambience and that fluid outlet FO1 is connected to fluid cell FC which may be used in a seat adjustment device of a vehicle seat such as vehicle seat VS of Fig. 1.

Valves PV, PV1, PV2, PV3 can assume three positions. In a first position, fluid port FP1 of first valve subassembly VSA1 is closed and fluid port FP2 of second valve subassembly VSA2 is closed. In a second position, only fluid port FP1 of first valve subassembly VSA1 is open and fluid port FP2 of second valve subassembly VSA2 is closed. In a third position, only fluid port FP2 of second valve subassembly VSA2 is open and fluid port FP1 of first valve subassembly VSA1 is open.

It is further assumed that valves PV, PV1, PV2, PV3 are present in the first position, i.e. in a position in which fluid ports FP1, FP2 are both closed.

Next, if fluid cell FC should be inflated, fluid port FP1 needs to be opened. For this, first valve subassembly cap Cl needs to move from the closed position to the open position. Therefore, electric power is applied to SMA wires SMA11, SMA12 so that a length of SMA wires SMA11, SMA12 is reduced, thereby moving sealing element SMI against the biasing force of biasing member BM1 from the closed position to the open position. Pressurized fluid such as pressurized air can then flow freely from fluid supply conduit inlet FSCI into pressure chamber PCI via fluid port FP1 and from there via fluid outlet F01 into fluid cell FC. As fluid port FP2 of second valve subassembly VSA2 is closed, pressurized fluid cannot flow from pressure chamber PCI into pressure chamber PC2 via connection passage CP.

Once fluid cell FC is inflated to a predetermined extent, fluid port FP1 is closed. For this, a supply of electric power applied to SMA wires SMA11, SMA12 is stopped. As a result, SMA wires SMA11, SMA12 extend to their original lengths and sealing element SMI is moved from the open position to the closed position by the biasing force of biasing member BM1.

Next, it is explained how fluid cell FC can be deflated. For this, fluid port FP2 needs to be opened so that pressurized fluid can flow from pressure chamber PCI via connection passage CP to pressure chamber PC2 and from there via fluid outlet F02 towards the ambience. To open fluid port FP2, electric power is applied to SMA wires SMA21, SMA22. As a result, SMA wires SMA21, SMA22 contract and sealing element SM2 is moved from the closed position to the open position against the biasing force of biasing member BM2 .

Although it is explained that valve subassemblies VSA1, VSA2 each include two SMA wires SMA11, SMA12 and SMA21, SMA22 being arranged parallel to each other and in a common plane P with lift axis LA. In other embodiments, valve subassemblies VSA1, VSA2 may each include more than two SMA wires, preferably multiples of two SMA wires, such as four or six SMA wires. In these embodiments, pairs of two SMA wires are preferably arranged so that for each pair, the two SMA wires are arranged parallel to each other and in a common plane with lift axis LA. In further embodiments, valve subassemblies VSA1, VSA2 may each include an uneven amount of SMA wires, such as three or five SMA wires. In these embodiments, the SMA wires are arranged symmetric around lift axis LA so that during a change of length of the SMA wires no tilting or bending of the valve cap occurs.

Claims (9)

Patent claims

1. A valve subassembly (VSA1, VSA2) of a valve (PV,

PV1, PV2, PV3) configured to control a fluid flow into and out of a fluid cell (FC, FC1, FC2) of a seat adjustment device of a vehicle seat (VS), the valve subassembly (VSA1, VSA2) comprising:

- a valve subassembly housing (Hl, H2) including a pressure chamber (PCI, PC2) and a fluid port (FP1, FP2) opening into the pressure chamber (PCI, PC2);

- a valve subassembly cap (Cl, C2, C3, C4) arranged inside the pressure chamber (PCI, PC2) and being movable along a lift axis (LA) between an open position for opening the fluid port (FP1, FP2) and a closed position for closing the fluid port (FP1, FP2) ; and

- at least one shape memory alloy wire (SMA11, SMA12, SMA21, SMA22, SMA3, SMA4) being coupled to the valve subassembly housing (Hl, H2) and the valve subassembly cap (Cl, C2, C3, C4), the at least one shape memory alloy wire (SMA11, SMA12, SMA21, SMA22, SMA3, SMA4) being configured to change its length in dependence of electric power applied to the at least one shape memory alloy wire (SMA11, SMA12, SMA21, SMA22, SMA3, SMA4) such that, upon applying electric power to the at least one shape memory alloy wire (SMA11, SMA12, SMA21, SMA22, SMA3, SMA4), the length of the at least one shape memory alloy wire (SMA11, SMA12, SMA21, SMA22, SMA3, SMA4) changes and causes the valve subassembly cap (Cl, C2, C3, C4) to move between the open position and the closed position, wherein the at least one shape memory allow wire (SMA11, SMA12, SMA21, SMA22, SMA3, SMA4) includes a bent section (BS) extending along a longitudinal direction (LD) parallel to the lift axis (LA), and the bent section (BS) includes at least one bent portion (BP) extending perpendicular to the longitudinal direction (LD).

2. The valve subassembly (VSA1, VSA2) of claim 1, wherein the at least one shape memory alloy wire (SMA11, SMA12, SMA21, SMA22, SMA3, SMA4 ) extends along a wire axis (WAI, WA2) extending substantially parallel to the longitudinal direction (LD) .

3. The valve subassembly (VSA1, VSA2) of claims 1 or 2, wherein the bent section (BS) extends substantially about the entire length (L) of the shape memory alloy wire (SMA11, SMA12, SMA21, SMA22, SMA3, SMA4).

4. The valve subassembly (VSA1, VSA2) of any one of the preceding claims, wherein the bent section (BS) at least partially includes a helical shape (HS).

5. The valve subassembly (VSA1, VSA2) of claim 4, wherein the helical shape (HS) is a circular helix.

6. The valve subassembly (VSA1, VSA2) of any one of the preceding claims, wherein the bent section (BS) at least partially includes a meander shape (MS).

7. The valve subassembly (VSA1, VSA2) of any one of the preceding claims, wherein the at least one shape memory alloy wire (SMA11, SMA12, SMA21, SMA22, SMA3, SMA4) includes a first straight end (El) coupled to the valve subassembly cap (Cl, C2, C3, C4) and a second straight end (E2) coupled to the valve subassembly housing (Hl, H2).

8. The valve subassembly (VSA1, VSA2) of any one of the preceding claims, further comprising:

- a biasing member (BM1, BM2) for biasing the valve subassembly cap (Cl, C2, C3, C4) towards the open position or the closed position.

9. The valve subassembly (VSA1, VSA2) of any one of the preceding claims, wherein the at least one shape memory alloy wire (SMA11, SMA12, SMA21, SMA22, SMA3, SMA4 ) comprises two shape memory alloy wires (SMA11, SMA12, SMA21, SMA22, SMA3, SMA4), each being coupled to the valve subassembly housing (Hl, H2) and the valve subassembly cap (Cl, C2, C3, C4) and each including the bent section (BS).