IES86396B2 - Valve for central heating and domestic hot water system - Google Patents

Abstract

The present invention relates to a valve for use in central heating and domestic hot water systems, to control the flow of water in the circuits of such systems. In particular the invention provides a valve comprising a valve body and valve actuator, the valve body being of a two or three port variety incorporating a valve closing member attached to a rotary valve stem, the valve actuator having a rotary spindle for interface with the stem of the valve body, the motive force for the rotation of the actuator spindle being the force generated in an SMA member when said member is subjected to a phase changing temperature transition. The advantage of the invention is the product longevity afforded by an SMA based actuator in contrast to the more limited longevity afforded by a motor is based actuator, motor based actuators being particularly vulnerable to motor burn out. <Figure 3b>

Description

TITLE S86396 Valve for Central Heating and Domestic Hot Water System.

FIELD OF INVENTION The present invention relates to a valve for use in central heating and domestic hot water systems so as to control the flow of water in the circuits of said systems.

BACKGROUND TO THE INVENTION Central heating and domestic hot water systems typically employ valves, (variously io referred to as zone valves or motorised valves) to control the flow of water in central heating and domestic hot water circuits in such a way as to provide fluid flew in the individual circuits or in both circuits simultaneously. Typically such valves comprise a valve body of lhe two or three-port variety and a valve actuator. Valve bodies typically employ two geometrically opposing valve ports into which a valve closing member attached lo a rotary valve stem is positioned to selectively close the ports. Valve actuators typically employ an electric motor, usually of the synchronous variety, to provide the motive force to rotate the valve stem and associated valve closing member. Valves of this type have been the subject of previous disclosures among them being EP 1 865 240 Al, GB 2 384 544 A, GB 2 384 288 A, GB2239077, and GB 2 265 689 A. Λ common problem associated with such valves is motor burnout of the actuator motor, usually due to the elevated ambient temperature and the frequent cycling of the motor. The valve of this present invention differs from those described in the aforementioned disclosures and subject to the aforementioned problem in that the motive force to actuate the valve is derived from a means other than an electric motor.

STATEMENT' OF INVENTION According to the invention there is provided a valve comprising a valve body and valve actuator, the valve body being of the two or thrcc-port variety having a valve closing member attached to a rotary valve stem, the valve actuator having a rotary spindle for interface with the stem of the valve body, the motive force for the rotation of the actuator spindle being the force generated in an SMA (shape memory alloy) member when said member is subjected to a phase changing temperature transition.

The advantage of the invention is the product longevity afforded by an SMA based actuator in contrast to the more limited longevity afforded by a motor based actuator, motor based actuators being particularly vulnerable to motor bum out.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more clearly understood from the following description of an embodiment thereof, given by way of an example only, with reference to the accompanying drawings in which: Figure la illustrates a two-port valve with both of its ports open to flow.

Figure lb illustrates a two-port valve with one port closed to flow and the other port open to flow.

Figure 2a illustrates a three-port valve with its leO hand and bottom ports open to Row. Figure 2b illustrates a three-port valve with all three of its ports open to flow.

Figure 2c illustrates a three-port valve with its right hand and bottom ports open to flow.

Figure 3a illustrates a two-port valve actuator in a state corresponding to the valve state illustrated in Figure lb.

Figure 3b illustrates a two-port valve actuator in a state corresponding to the valve stale illustrated in Figure la, F igure 3e illustrates a two-port valve actuator in partial section, Figure 4a illustrates a three-port valve actuator in a state corresponding to the valve state illustrated in Figure 2a Figure 4b illustrates a three-port valve actuator in a state corresponding to the valve stale illustrated in Figure 2b Figure 4e illustrates a three-port valve actuator in a state corresponding to the valve state illustrated in Figure 2c DETAILED DESCRRIPT1ON An embodiment of a two-port valve body in accordance with the invention is illustrated in Figures la and lb. The valve body (1) contains two valve ports (4,5), A valve closing member (2) attached to a rotary valve stem (3) passes through, and is free to rotate in, the valve body (1), and can assume either of two preferred positions relative to the valve ports (4,5). The first preferred positions is against one of the valve ports thus blocking off said valve port and rendering the valve closed to fluid flow. This situation is as illustrated in Figure lb. 1’he second preferred position is intermediate to the valve ports (4,5) in a manner as to render the valve open to fluid flow. This situation is as illustrated in Figure la.

An embodiment of a threc-port valve body in accordance with the invention is illustrated in Figures 2a, 2b and 2c. The valve body (1) includes three valve ports (4, 5,6), fluid flow being possible from each of the three ports to the remaining two ports, tire first port (6) being is a slate of permanent openness, A valve closing member (2) attached to a rotary valve stem (3) passes through, and is free to rotate in, the valve body (1), and can assume !0 either of three preferred positions relative to the second and third valve ports (4,5), The first preferred position is against the second port (5), thus rendering said port closet! to fluid flow. This situation is as illustrated in Figure 2a. The second preferred position is intermediate to the second and third ports (4,5) so as to render all three ports open to fluid flow. This situation is as illustrated in Figure 2b. The third preferred position is against the third port (4) thus rendering said port closed to fluid flow. This situation is as illustrated in Figure 2c.

An embodiment of a two-port valve actuator in accordance with the invention is illustrated in Figures 3a, 3b and 3c. An actuator spindle (12) passes through a hole at the centre of the actuator bousing (11) so lhat both spindle (12) and actuator housing (11) share a common axis (22), and the spindle (12) is free to rotate relative to the actuator housing (11) about this common axis ¢22). One end of the SMA member ¢13) is connected to the actuator housing (11) al an attachment ¢14), and its other end is connected to the spindle (12) at an attachment (15). Electrical power is provided via the electric controls unit ¢16). Current supply wires (17,18) arc connected to the ends of the SMA member (13) at attachments (14, 15), and link back to the electric controls unit (16), thus forming a continuous electrical circuit. The spindle (12) is connected to the actuator housing (11) by a biasing spring (19) which tends to retain the spindle (12) against a stop (20), said stop being an integral part of the actuator housing (11). The actuator spindle (12) reduces down in diameter at its base. This reduced diameter portion (21) serves lo interface the actuator spindle (12) to the stem of an associated valve body. In addition to this coupling of the actuator spindle (12) to the stem of a valve body the actuator housing (11) is firmly attached to said valve body by a means not here indicated, so that any rotation of the actuator spindle (12) results in a corresponding rotation of the valve body stem and not in a rotation of the actuator housing (11) relative to the valve body.

When there is no electrical current flowing in the SMA member (13) the spindle (12) is retained against the stop (20) by the force of the biasing spring (19). This resulting actuator spindle position is as shown in Figure 3 a, and corresponds to a valve body closed to fluid flow as illustrated in Figure lb.

When electrical current of suitable magnitude, (ic: of magnitude sufficient to bring about to a temperature rise in the SMA member capable of making said SMA member pass through its phase changing temperature transition) is made to flow in SMA member (13) the force generated in said SMA member overcomes the opposing force provided by the biasing spring (19), thus allowing the spindle (12) the freedom to move away from the stop (20). The accompanying phase-change related contraction of the SMA member (13), tn combination with the spindle (12) and actuator housing (11) being constrained to a common axis (22), dictates that the path of the movement of the spindle (12) away from the stop (20) is a rotation of the spindle ¢12) about the common axis (22). This rotated spindle position is indicated by angle :a? as shown in Figure 3b, and corresponds to a valve body open to fluid flow as illustrated in Figure la.

An embodiment of a thrcc-port valve actuator in accordance with the invention is illustrated in Figures 4a, 4b and 4c.

The actuator spindle (32) passes through a hole at the centre of the connector plate (3 [) and also through a hole at the centre of the actuator housing (30), so that a common axis (48) is shared by all three members (30, 31, 32). and all three members are capable of rotation relative to one another about this shared axis (48), The actuator spindle (32) reduces down in diameter at its base. This reduced diameter portion (49) selves to interface the actuator spindle (32) to the stem of an associated valve body. In addition to this coupling of the actuator spindle ¢32) to the stem of a valve body, the actuator housing (30) is firmly attached to said valve body by a means not here indicated, so that any rotation of the actuator spindle (32) results in a corresponding rotation of the valve body stem and not in a rotation of the actuator housing (30) relative to the valve body.

One end of a first SMA member (33) is connected to the actuator housing (30) at an attachment (34), and its other end is connected to the connector plate (31) at an attachment (47). A first biasing spring (38) connects the connector plate (31) to the actuator housing (30) and tends to retain the connector plate (31) against a first stop (39), said stop being an integral part of the actuator housing (30). Electrical power is provided via the electric controls unit (42). Current supply wires (43, 44) arc connected to the ends of the first SMA member (33) at the attachments (47, 34), and link back to the electric controls unit (42), thus forming a continuous electrical circuit.

One end of a second SMA member (35) is connected to the actuator spindle (32) at an attachment (36), and at its other end to the connector plate (31) at an attachment (37). A second biasing spring (40) connects the spindle (32) to the connector plate (31) and tends to retain the spindle (32) against a second stop (41), said stop being an integral part of the connector plate (31). Current supply wires (45, 46) are connected to the ends of the second SMA member (35) at the attachments (36, 37), and link back to the electric controls unit (42), thus forming a continuous electrical circuit.

When there is no electrical current flowing in the SMA members ¢33, 35) the connector plate (31) is retained against the stop (39) of the actuator housing (30) by the force of the first biasing spring (38), and the spindle (32) is retained against the stop (41) of tire connector plate (31) by the force of the second biasing spring (40), The resulting actuator spindle position is as shown in Figure 4a, and corresponds to a single port of a valve body being closed to fluid flow as illustrated in Figure 2a.

When electrical current of suitable magnitude, (ie: of magnitude sufficient to bring about a temperature rise in the SMA member capable of making said member pass through its phase changing temperature transition), is made to flow in the first SMA member (33), the force generated in said SMA member overcomes the opposing force exerted by the first biasing spring (38), thus allowing the connector plate (31) the freedom to move away from the first stop (39). The accompanying phase-change related contraction of the first SMA member (33), in combination with the connector plate (31) and actuator housing (30) being constrained to a common axis (48), dictates that the path of the movement of the connector plate (31) away from the first stop (39) is a rotation of the connector plate (31) relative to the actuator housing (30), At the S3me time as this rotation of the connector plate (31) is occurring, the actuator spindle (32) is being forced to rotate through the same angle relative to the actuator housing (30), because the second biasing spring (40) effectively locks the spindle (32) to the connector plate (31) causing the two to move as a single unit. The resulting actuator spindle position is as indicated by angle V in Figure 4b, and corresponds to all three ports of a valve body being open to fluid flow as illustrated in Figure 2b.

When electric current of phase-changing magnitude is made to flow in both SMA members (33, 35) tire SMA generated forces dominate the forces exerted by the biasing springs (38, 40), resulting in the connector plate (31) rotating relative to the actuator housing (30), and the actuator spindle (32) rotating relative to the connector plate (31). The overall result in a compound rotation of spindle (32) relative to the actuator housing (30). The resulting actuator spindle position is as indicated by angle ‘y’ in Figure 4c, and corresponds to a single port of a valve body being closed to fluid flow as illustrated in Figure 2c.

Claims (5)

1. Claim 1 . A valve for use in domestic hot water and central heating systems comprising a valve body and valve actuator, said valve body having at least two valve ports and a valve closing member, said closing member being attached to a rotary valve stem, said closing 5 member and stem being capable of being rotated so as to either open or close at least one of the valve ports, said valve stem passing through the wall of the valve body and being attachable to a spindle of the valve actuator, said valve actuator providing, via its spindle, a means of motive force to rotate the valve body stem and thus effect the opening or closing of a valve port or ports, said motive force originating in an SMA member of the 10 valve actuator, and being generated in response to a change in temperature of said SMA member, said change in temperature being brought about in by electrical means.
2. Claim 2, A valve actuator as claimed in Claim 1, wherein the motive force to rotate the spindle of said actuator originates in an SMA member of said actuator, said motive force 15 being generated in response to a change in temperature of said SMA member, said change in temperature being brought about by electrical means, said electrical means being either direct as in the case of a heating current being passed through the SMA member, or indirect, in which case an electric current is employed to produce or control the required temperature change of the SMA member by some means other than by the resistive 20 headn g o f the SMA mem ber itsel f. 2.
3. Claim 3. A valve as claimed in Claim 1, wherein the valve body includes two valve ports and a valve closing member capable of assuming two preferred positions relative to said 25 ports, one such preferred positions being a position against or within one of the valve ports so as to render the valve closed to fluid flow, the other preferred position being intermediate to the valve ports in a manner as to render the valve open to fluid flow. 30 3.
4. Claim 4. A valve as claimed in Claim I, wherein the valve body includes three valve ports, fluid flow being possible from each of the three ports to the remaining two ports, the first port being is a state of permanent openness, the valve closing member being capable of assuming three preferred positions relative to the second and third ports, the first preferred positions being against or within the second port so as to render said port closed to fluid flow, the second preferred position being intermediate to the second and third ports so as to render all three ports open to fluid flow, and the third preferred position being against or within the third port so as to render said port closed to fluid flow. 4.
5. Claim 5. A valve as substantially hereinbefore described with reference to the accompanying description and/or drawings.