IE20030706A1 - Valve and valve actuator - Google Patents

Abstract

An actuator for a motorised valve is disclosed, as is a motorised valve incorporating a valve body and such an actuator. The actuator comprises an output member (32), a motor (10), and a transmission for connecting the motor to the output member. The motor can drive the output member between first and second extreme operational positions through the transmission to operate a valve body towhich it is connected. The transmission has lost motion, whereby the output member can be moved by a manual control (40) between the first and second extreme operational positions substantially without causing movement of the motor.

Description

This invention relates to a valve and a valve actuator. Specifically, relates to a valve and valve actuator that can be assembled to provide a motorised valve for use in controlling the flow of water in a central heating system.

Virtually all central heating systems incorporate one or more motorised valves for controlling flow of water within the system. Each motorised valve includes a valve body that actually controls the flow, and an actuator that drives an operational mechanism (typically a spindle) of the valve body into one of several positions that determine the pattern of flow within the valve body. The actuator can be operated by a controller or thermostat of the heating system, thereby enabling the controller or thermostat to control the flow of water within the system.

Typically, two types of valve are provided for use in central heating systems. A two15 port valve is a simple on/off controller that can selectively allow or prevent flow from a single input port to a single output port. A three-port valve has a single input port, and can pass flow from it to one of two output ports.

Known motorised valves are provided with a motor coupled to the spindle (or other operational mechanism) of the valve body through a reduction gearbox. Thus, the motor turns relatively quickly and generates relatively little torque as compared with the spindle.

In the most usual existing configuration, application of power to the motor drives the spindle in one direction, the spindle being turned in the other direction by the action of a spring. When power is removed from the motor, the valve returns, under the action of the spring, to an unenergised condition (typically, closed in a two-port and to a “hot water” position in a three-port valve). The valve is maintained in any other static condition with the motor energised but stalled. In a typical heating system, this means that the motor consumes power continually during normal operation of the system, IE 0 3 0 7 0 6 which is wasteful of energy and can result in the motor having a short life before failure. Furthermore, there is a requirement that motorised valves are provided with a manual override to enable commissioning of the system or operation of the valve in the event of failure of the actuator. This mandates that the motor must require a minimum of torque to turn in the absence of power, since, during manual operation, it is being driven through the gearbox, which acts as an overdriving gearbox, so that the torque required to turn the motor is multiplied. Motors that meet this requirement of low torque and an ability to be stalled for an extended period are expensive, contributing significantly to the cost of the actuator.

An aim of this invention is to provide a motorised valve and a valve actuator that can fulfil the role of a conventional motorised valve without the need to use specialised expensive motors. It is also an aim of this invention to provide a motorised valve and a valve actuator that uses less power than an equivalent conventional motorised valve.

From a first aspect, this invention provides an actuator for a motorised valve comprising an output member, a motor, and a transmission for connecting the motor to the output member, whereby the motor can drive the output member between first and second extreme operational positions through the transmission, and wherein the transmission has lost motion, whereby the output member can be moved between the first and second extreme operational positions substantially without causing movement of the motor.

This arrangement has several advantages. First, the motor is only required to drive the output member to a position; it is not required to hold it there. Thus, the motor need not be capable of withstanding a prolonged stall, and it does not consume power while the output member is not actually being moved. Moreover, the extent of lost motion in the transmission allows the output member (and any valve spindle connected to it) to move between the first and second extreme operational positions without causing the motor to move. Therefore, there is no need to provide a motor that has particularly low resistance to un-powered movement.

The transmission most usually includes a manual control by means of which a user can move the valve manually. The user control may enable a user to move the output member of the transmission.

IE 0 3 0 7 0 6 For example, the motor may be a synchronous motor. Such motors are readily available at low cost, and have good torque characteristics for this application.

In addition to the extreme operational positions, there may be one or more intermediate operational positions. (In the case of a three-port valve, there would be one intermediate operational position.) Again, once the motor has driven the output member to an intermediate operational position, there is no need to maintain the motor in an energised state.

The output member may typically be a spindle that can be rotated by the transmission about an axis. For example, the extreme operational positions may be extreme rotational positions of the spindle. These may be separated by angles of up to 90°, 180° or 270° in typical embodiments. In the case of a three-port valve, the intermediate operational position may be a rotational position mid-way between the extreme operational positions.

As will be understood, an actuator embodying this invention most typically has no spring or similar means for driving its output member. Therefore, the motor is most typically operable to drive the output member both from the first to the second extreme operational position and from the second to the first extreme operational position. Such drive may be in one direction or may be in opposite directions.

Although motorised valves have been proposed that rely on a motor to drive the valve into both an on and an off condition, these have required specific adaptations to be made to a heating system into which they are to be installed, as compared with a conventional spring-return valve. Particular embodiments of this invention further include an electrical control system that presents an external interface that corresponds to that of a conventional spring-return valve. Most advantageously, the control system is contained within a housing of the actuator. This allows such a valve embodying this invention to serve as a replacement for an existing spring-return valve or as a new installation in an otherwise conventional central heating system.

Some embodiments of the invention may have limited lost motion within the drive. For example, the lost motion may be just sufficient to allow movement between the extreme operational positions. This can be likened to a drive with a large amount of lash.

IE 0 3 0 7 0 6 Alternatively, the lost motion can be substantially unlimited, for example, by providing a one-way (e.g. ratchet) drive between the motor and the output member.

Lost motion may be provided between the motor and the output member. In such embodiments, the output member can be moved manually to position the valve without introducing lost motion into the manual operation of the valve. Alternatively, it may be between the output member and a valve spindle to which it is connected for use.

Most typically, the actuator includes a manual control that a user can operate to move the valve within the extent of the lost motion.

From a second aspect, this invention provides an actuator for a motorised valve comprising a motor drive connected to an output member, the output member being cooperable with an input member a valve body to move the valve body between a plurality of operative positions, in which the actuator includes control circuitry that enables the motor to drive the valve to each of the plurality of operative positions.

This enables provision of a valve that is powered to each of its operative positions without the need to provide a spring return within the actuator and without the need to provide an external control system.

Embodiments of this invention may present an external electrical interface that is compatible with conventional motorised valves. A valve embodying this aspect of the invention may incorporate combinations of the optional features of the first aspect of the invention, as defined above.

From a third aspect, this invention provides an electrically operated valve operatively connected to an actuator embodying the first aspect of the invention.

Another aspect of the invention provides an electrically operated valve comprising an actuator and a valve body, there being a snap-fit interconnection between the valve body and the valve actuator. This can obviate the need to provide a screw or other fastener to interconnect these components, which can be very convenient if the valve is to be installed in a confined space. For example, the snap-fit components may be IE 0 3 07 0 β concentric with the valve spindle. A locating peg may be provided to resist rotational movement between the valve body and the actuator.

An embodiment of the invention will now be described in detail, by way of example, and with reference to the accompanying drawings, in which: Figure 1 is a partly exploded general assembly view of an actuator for a motorised valve embodying the invention; Figure 2 is an enlarged view of a motor and components of a transmission of the embodiment of Figure 1; Figure 3 shows interconnecting components of a valve body and a valve actuator in a valve embodying the invention; Figure 4 is a circuit diagram of control electronics for a two-port valve embodying the invention; and Figure 5 is a circuit diagram of control electronics for a three-port valve embodying the invention.

The embodiment that will be described is a two-port valve for use in a heating system. The modifications to this embodiment that must be made in order to implement a threeport valve will also be described.

With reference to the drawings, an electrically operated valve embodying the invention is formed from two principal sub-assemblies: a valve body and an actuator.

In this embodiment, the valve body is a conventional two-port valve. The valve can be moved between a closed condition and an open condition by rotation of an operating spindle through 90°. The spindle has a flattened end portion that can be used to couple to it to provide a coupling for rotational drive to the operating spindle.

The operative components of the actuator assembly are shown in Figures 1 and 2.

The actuator assembly comprises an actuator chassis 20 onto which its components are assembled. In this embodiment, the actuator chassis 20 is formed as a one-piece IE 0 3 0 ί β 6 moulding of plastic material. The actuator chassis 20 has a generally flat base portion 22. A pair of towers 24 project from the base portion 22.

The actuator assembly includes a motor drive 10, which in this embodiment is a synchronous unit rated to be driven by a local AC mains supply (230 V at 50 Hz in Europe and 110 V at 60 Hz in North America, for example). The motor drive 10 incorporates a synchronous motor and a reduction gearbox within a common housing. The motor drive 10 has an output shaft that rotates slowly (about 1 or 2 rpm, in this embodiment) and with high torque. The drive unit 10 has a pair of projecting lugs 26 fixed to the housing, each of which is connected to a respective one of the towers 24 of the actuator chassis. In this way, the drive unit is supported spaced from the base portion 22.

Output of the motor drive is obtained at an output shaft 12 that extends from the housing towards the base portion and that has a rotational axis substantially normal to the plane of the base portion 22. An inner part 14 of the output shaft 12 is coupled to the gearbox within the motor drive 10. From the inner part 14, a cylindrical part of the output extends coaxially with the inner part to an end face 16. A drive dog 18 projects from the end face 16. The drive dog 18 extends from approximately the rotational axis of the output shaft radially outwardly.

A coupling component 30, formed in this embodiment as a one-piece plastic moulding, is carried on the base portion 22. The coupling component can rotate upon the base portion 22 about an axis that is substantially coincident with the axis of the output shaft 12. The coupling component 30 can be considered to have an axis coincident with its axis of rotation, and this axis can be referred to as a convenient reference for description of the component.

The coupling component 30 has an input side and an output side integrally connected to one another and spaced along the axis. The input side, in the completed assembly, is directed towards the motor drive 10.

The input side has an axial bore that has a basically circular cross section with an axially-extending rib 32 projecting from the peripheral wall into the bore from its outer surface to a depth of approximately 25% of the diameter of the bore. The rib 32 has IE Ο 3 0 7 0 6 outer walls that are substantially at 90° to one another. In the assembly, the output shaft 12 of the motor drive extends into the bore such that the end face 16 is a good fit into the upper portion of the inner diameter and provides an upper bearing for the drive. The drive dog 18 also extends into the bore to a greater depth such that the drive dog 18 and the rib overlap axially.

Thus, when the motor drive 10 is energised, its output shaft 12 rotates until the drive dog 18 contacts the rib 32. Thereafter, the connecting member 30 is driven around by the motor in what will be referred to as the “forward direction”. It should also be understood that after the motor drive 10 is de-energised, the connecting member 30 can continue to move in the forward direction until the drive dog 18 comes into contact with the opposite side of the rib 32. Thus, there is lost motion in the transmission system that allows freedom of for the output member to move in the forward direction beyond the extent to which it has been driven by the motor. In this embodiment, the drive member can turn through approximately 270° in this way.

An outer surface of the input side is substantially cylindrical with two cam slots (one shown at 34) extending axially into the outer surface, each forming a single, axially extending groove in the outer surface. The two cam slots are spaced apart circumferentially 90° and axially on the outer surface. The purpose of the cam slots 34 will be described in due course. Also formed on the outer surface of the input side is a toothed region 36. This forms a spur gear integrally with the outer surface of the coupling component 30.

The output side of the coupling component 30 has a cylindrical outer surface and a flat end surface. A recess 38 extends into the output side through the end surface. The recess has a cross-sectional shape such that it can receive the spindle of the valve body and couple to it for rotation and act as an output member of the actuator. The output side extends through a circular-section bore 46 in the base portion 22 of the actuator chassis 20 such that the coupling component 30 is borne for rotation about its axis.

The actuator further includes a manual control wheel 40, formed as a moulding of plastic material that is approximately rotationally symmetric about an axis.

IE 0 S 0 7 0 6 The manual control wheel 40 includes a cylindrical axial spigot that passes through a circular-section bore in the base portion 22 of the actuator chassis 20 such that the control wheel is borne for rotation about its axis. A spring clip is applied to the spigot to prevent its removal from the bore. A gear portion 42 of the control wheel is formed with external teeth to constitute a spur gear. The gear portion 42 is in mesh with the toothed region 36 of the coupling component 30. Adjacent to the gear portion 42, and of larger diameter, is a thumbwheel portion 44 on which is formed grooves, knurls or the like to provide a surface upon which a user can obtain a grip to rotate the manual control wheel 40. In addition, by virtue of its larger diameter, the thumbwheel portion 44 overlies the toothed region 36 restricting its axial movement, and thereby preventing removal of the coupling component 30 from the base portion 22. A flat area is formed on the thumbwheel portion 44. The relative position of the control wheel 40, the coupling component 30 and the valve spindle is such that the valve will be in its open position when the flat faces away from the coupling component 30 and flush with the outside of the actuator cover when fitted.

Electronic control circuitry for the actuator is carried on a circuit board 60 that is carried on and projects normally from the base portion 22. Two microswitches 62 are carried on the circuit board 60 one upon the other, each microswitch 62 having an operating button that lies against the outer surface of the input side of the coupling component 30. As the coupling component 30 rotates, each of the operating buttons can fall into a respective one of the cam slots 34 when the respective slot is adjacent to the microswitch, thereby changing the state of the microswitch.

The coupling component 30 is disposed in relation to the valve spindle such that a first one of the microswitches is operated when the valve is in the closed condition and such that the other is operated when the valve spindle is in the open condition.

As can be seen in Figure 3, the base portion 22 of the actuator chassis 20 is connected to a baseplate 70 of the valve body. A cylindrical upstanding locating formation 72 of the baseplate surrounds the valve spindle (not shown). A locating ring 74 is retained within an inwardly-directed groove of the locating formation 72. A corresponding locating formation 46 is carried on the base portion 22, having an outwardly projecting barb formation that cooperates with the locating ring 74 to retain the actuator on the ΙΕ η 3 Ο 7 ο 6 baseplate 70. The locating formation 46 is formed as three separate segments to provide sufficient resilience to enable the barbs to snap over the locating ring. A conventional register peg and optionally a screw can optionally also be provided to secure the actuator in place. For example, a peg on the valve body remote from the valve spindle may locate within a hole in the actuator chassis to resist rotation between these components.

All of the above components of the actuator may be enclosed within a housing (not shown). An opening in the housing provides access to part of the thumbwheel portion 44 of the manual control wheel 40.

As with a conventional spring-return valve, the control electronics, as shown in Fig. 4, has four input wires coloured brown, blue, orange and grey. As with a spring-return valve, there is one wire (the brown wire) that controls both opening and closing of the motorised valve. When mains power applied to the brown wire, this is a signal to open the valve. When this power is removed, the control circuitry provides the required signal to the motor drive 10 to close the valve.

As shown in Fig 4, the brown input is reduced in voltage and rectified by a series capacitor Cl, a bridge rectifier BRI and a parallel capacitor C2. The blue wire provides a return path for the AC input. This provides a low voltage DC signal for operation of a relay RL1. When power is applied to the brown wire, the relay RL1 operates and is held closed to cause mains applied to the grey wire to be transferred to a first of the microswitches, labelled Sl in Fig 4. The microswitch Sl transfers power from the grey wire to the motor drive 10, causing it to start rotating. This, in turn, drives the connecting member 30 and the valve spindle in the forward direction, once all lost motion has been taken up.

Movement continues until the button of the microswitch Sl enters the corresponding cam slot 34. This turns the microswitch Sl off, and the motor drive stops. At this time, the valve is in the open condition. Inertia and friction hold the valve in the open position without the need for power on the motor. While in the open position relay RL1 remains energised, but there is no power on the motor.

IE 0 3 o / β 6 To move the valve to the closed position, power is removed from the brown wire. This causes the relay RL1 to de-energise, transferring the power from the grey wire to the second microswitch S2. The second microswitch S2 coveys power to the motor drive 10, causing it to start rotating. This drives the connecting member and the valve spindle until the button of the second microswitch enters the respective cam slot. This occurs when the valve body is in the closed position. Power is removed from the motor drive 10. As before, Inertia and friction hold the valve in the closed position without the need for power on the motor.

At any time following operation of the motor to open or close the valve, there is 10 available 270° of free motion of the coupling member in the forward direction. A user can move the manual control wheel 40 to drive the coupling member 30 by up to 270° through the spur gear system. The presence of the flat on the control wheel 40 indicates to the user when the valve is open.

A three-port version modification to the valve requires a third microswitch S3 that is 15 operated by a cam on the connecting member 30 at a position mid-way between the two cam slots described above, and at a further position 180° away from that position. The valve body has an input and two outputs. In a first condition, labelled CH, all flow in the input is directed to the output connected to a central heating system. In a second condition, labelled HW, all flow in the input is directed to the output connected to a hot water system. In a third condition, labelled MID, flow in the input is directed to both of the outputs described above.

The valve has four input lines coloured orange, grey, blue and white, as is conventional. The blue wire is the neutral return. The condition of the valve is determined by application of power to other three input lines, as follows: IE Ο 3 Ο / Ο 6 Valve Position Input State Orange Grey White CH Off On On HW On Off Off MID On Off On As will be understood, this is identical to the signals and their effects as applied to a conventional spring-return three-port valve.

With reference to Figure 5, in this embodiment, a capacitor Cl, a bridge rectifier BRI and a capacitor C3 drop and rectify a mains input applied to the grey wire, resulting in a lower DC voltage to operate a first relay RL1. Similarly a capacitor C2, a bridge rectifier BRI and a capacitor C4 drop and rectify a mains input applied to the white wire, to operate a second relay RL2.

When mains power is applied in various combinations to the orange, grey and white wires according to the above table the actuator integrated electronics acts as follows: Signal to move to CH position: orange off; grey on; white on. The first relay RL1 is energised holding both poles of its switch in the n/o position. The second relay RL2 is also energised holding its single pole switch in the n/o position. This condition supplies mains power to the switch SI only (i.e. Ov is applied to S2 and S3). The switch SI transfers the voltage to the motor drive 10 causing it to start rotating, and in turn to drive the coupling member 30 once any lost motion has been accommodated. When the cam slot associated with the switch SI comes into line with it, at which point the switch changes state. The position of this cam slot corresponds to the valve being in the CH position. This removes the power from the motor drive 10, such that friction and inertia holds the valve in the CH position without the need for power on the motor. While in the CH position both relays RL1 and RL2 remain energised, but there is no power on the motor drive 10. If the valve were already in the CH position, the switch would allow no power would be applied to the motor. When the CH position is reached S1 switches mains power to the orange wire. This is used to power on the boiler and heating pump.

Signal to move to HW position: orange on; grey off; white off. Neither relay RL1 nor RL2 is energised. This condition supplies mains power to switch S2 only (i.e. 0V is applied to SI and S3). The switch S2 transfers the mains power to the motor drive 10 causing it to start rotating driving. When the cam slot associated with the switch SI comes into line with it, at which point the switch changes state. The position of this cam slot corresponds to the valve being in the HW position where it is held by friction and inertia. While in the HW position, neither relay RL1 nor RL2 is energised, nor is there no power on the motor drive 10. If S2 were already in the HW position, no power would be applied to the motor. The mains power is supplied to the orange wire to power the boiler and pump.

Signal to move to MID position: orange on; grey off; white off. The second relay RL2 is energised. This condition supplies mains power to the third switch S3 only (i.e. 0V is applied to SI and S2). S3 transfers power to the synchronous motor causing it to start rotating driving the valve via the coupling component 30. The cam 35 on the coupling component 30, operates the microswitch S3 when the coupling component is in a position corresponding to the MID position. This removes the power from the motor drive 10 when that position is reached. There can be two MID positions 180 degrees angular apart. The motor drive 10 will stop at whichever it reaches first and it will remain there by friction and inertia. While in the MID position, the relay RL1 is deenergised and the relay RL2 is energised. There is no power on the motor drive 10. Mains power on the orange wire powers the boiler and pump.

As with the two-port valve, there is sufficient lost motion in the actuator such that a user can move the valve to any position using the manual control wheel 40.

The above embodiment uses a three-port valve body that has two valve shoes on a spindle 90° apart and with 90° of movement between the extreme operational conditions. An actuator, in the invention, could easily be adapted for use with a threeIE 0 J Ο 7 Ο β port valve with just one shoe, there being in such embodiments 180° of movement between the extreme operational conditions.

In alternative embodiments, a one-way drive may connect the motor drive, directly or indirectly, to the valve spindle. This provides little lost motion in the reverse direction, but effectively unlimited lost motion in the forward direction.

In a further alternative embodiment, where manual control is not required the motor drive 10 may connect directly or indirectly to the valve spindle through a transmission that provides little lost motion in either direction. In such embodiments, the thumbwheel portion 44 is omitted.

Claims (27)

Claims

1. An actuator for a motorised valve comprising an output member, a motor, and a transmission for connecting the motor to the output member, whereby the motor can drive the output member between first and second extreme operational positions through the transmission, and wherein the transmission has lost motion, whereby the output member can be moved between the first and second extreme operational positions substantially without causing movement of the motor.

2. An actuator according to claim 1 in which the transmission includes a manual control by means of which a user can move the valve manually.

3. An actuator according to claim 2 in which the manual control enables a user to move the output member of the transmission.

4. An actuator according to any preceding claim in which the motor is a synchronous motor. 5. 10. An actuator according to claim 6 for a three-port valve in which the intermediate operational position may be a rotational position mid-way between the extreme operational positions.

5. An actuator according to any preceding claim in which in addition to the extreme operational positions, there is one or more intermediate operational positions.

6. An actuator according to claim 5 in which once the motor has driven the output member to an intermediate operational position, the motor need not be maintained in an energised state to maintain the output member in the intermediate operational position.

7. An actuator according to any preceding claim in which the output member is a spindle that can be rotated by the transmission about an axis. IE03 0 ? ® 8

8. An actuator according to claim 7 in which the extreme operational positions are extreme rotational positions of the spindle.

9. An actuator according to claim 8 in which the extreme operational positions are separated by an angles of up to one of 90°, 180° or 270°.

10. Operational position and from the second to the first extreme operational position.

11. An actuator according to any preceding claim in which the motor is operable to drive the output member both from the first to the second extreme

12. An actuator according to any preceding claim further including an electrical control system that presents an external interface that corresponds to that of a conventional spring-return valve. 15

13. An actuator according to claim 12 in which the control system is contained within a housing of the actuator.

14. An actuator according to any preceding claim in which there is limited lost motion within the drive.

15. An actuator according to claim 14 in which the lost motion is just sufficient

16. An actuator according to claim 14 in which the lost motion can be substantially unlimited by providing a one-way drive between the motor and the output member.

17. An actuator according to any preceding claim in which lost motion is provided between the motor and the output member. IE 0 3 0 7 0 6

18. An actuator according to any preceding claim in which lost motion is provided between the output member and a valve spindle to which it is connected for use.

19. An actuator according to any one of claims 14 to 18 which includes a manual control that a user can operate to move the valve within the extent of the lost motion.

20. An actuator for a motorised valve comprising a motor drive connected to an output member, the output member being co-operable with an input member a valve body to move the valve body between a plurality of operative positions, in which the actuator includes control circuitry that enables the motor to drive the valve to each of the plurality of operative positions. 20 to allow movement between the extreme operational positions.

21. An actuator according to claim 20 that presents an external electrical interface that is compatible with a conventional motorised valve.

22. An actuator for a motorised valve substantially as herein described with reference to the accompanying drawings.

23. An electrically operated valve comprising a valve body operatively connected to an actuator according to any preceding claim.

24. An electrically operated valve according to claim 23, there being a snap-fit interconnection between the valve body and the valve actuator.

25. An electrically operated valve according to claim 24 in which the snap-fit components are concentric with the valve spindle.

26. An ele'cttfcally operated valve according to claim 24 or claim 25 further ‘ ,· ,· fil including a locating peg to resist rotational movement between the valve body and the actuator.

27. An electrically operated valve substantially as herein described with reference to the accompanying drawings.