GB2092712A - A motor driven control valve - Google Patents

Abstract

The control valve has a valve body (3) made of metal and defining an inlet port (4) and two outlet ports (5, 6). A valve member (7) is movable by a valve spindle (15) between a first end position against a valve seat (9) and a second end position against a valve seat (8). The valve spindle (15) is rotated by a control and drive unit (2) including an electric motor (17). The motor (17) is housed within a casing of plastics material comprising a moulded base member (18) and a removable cover (19). The base member (18) has fixed and/or supporting means for components of the control and drive unit (2). The base member (18) is supported on three spaced pillars (10, 11, 12) extending from the valve body (3). As the base member (18) is made of plastics material it insulates the unit (2) from the valve body (3). Furthermore, the pillars (10, 11, 12) do not project into the casing and thus they do not provide a path for heat through the base member (18). <IMAGE>

Description

SPECIFICATION A motor driven control valve The present invention relates to a motor driven control valve.

Motor driven control valves are particularly suitable for controlling fluid flow through one or more circuits and the valves may be of different sizes and used to control various media. The valves commonly have one inlet port and one or more outlet ports.

One example of the use of such motor driven control valves is in the control of a hot water and central heating system in which valve means is necessary to control flow of hot water from a boiler into either a hot water system or a central heating system. It is well known to use a three port valve for this purpose, the hot water from the boiler being diverted either to the domestic hot water system or to the central heating system. The valve has a valve member, for example a vane or ball type member that blocks either the hot water port or the radiator supply port from the valve. The valve member is coupled to the electric motor such that the motor is operable to move the valve member across the valve to block one port and open the other port.The motor may be reversible such that the motor is operable to move the valve member across the valve in both directions or the valve member may be spring loaded against one port and moved to block the other port when electrical power is supplied to the motor.

Generally the control valve has a metal valve body, for example in the form of a brass hot pressing, in which the valve member is arranged and which defines the ports. This valve body defines and/or supports a housing for drive means, which includes the motor, and the associated circuitry. In known valves metal pillars extend from the valve body into the housing and provide supports for the motor. The housing is also generally made of metal, for example, of aluminium.

Where the control valve is used to control the flow of a hot fluid, for example, hot water, heat from the fluid is conducted into the housing, and raises the operating temperature of the motor. If the motor frequently operates at high operating temperatures the length of its operating life is decreased.

According to the present invention there is provided a motor driven control valve comprising a valve body defining two or more ports, a valve member connected to a valve spindle and arranged within said valve body to be movable between at least two predetermined positions, and drive means, including an electric motor, coupled to said valve spindle for driving said valve member between said predetermined positions, wherein said drive means are mounted in a housing having a base member made of plastics material, said base member being supported on two or more pillars extending from the valve body such that said pillars do not project into said housing.

As the base member is made of plastics material it insulates the drive means from the valve body. Thus, even if the valve body becomes hot because a hot fluid is passing through it the motor remains at a lower temperature and this can increase the operating life of the motor.

Furthermore, as the pillars do not project into the housing they do not provide a path for heat through the base member.

The only member which extends in both the valve body and the housing is the valve spindle.

Preferably the valve spindle extends in the housing within a sleeve of plastics material whereby it is insulated from the interior of the housing.

In an embodiment three spaced pillars extend from the valve body and are preferably integrally formed therewith. A first one of the pillars is hollow and provides a guide passage for the valve spindle. The other two pillars are each spaced from the first pillar and are fixed to the base member. Preferably said other two pillars are located at opposite ends of the valve body to provide maximum stability for the housing whilst requiring the minimum of manufacturing accuracy.

The two end pillars preferably abut the base member. The hollow pillar preferably has a reduced diameter upper end portion which extends within a bore provided in the base member.

Preferably all of said housing is made of plastics material. The housing may comprise a removable cover held on said base member.

In an embodiment the plastics material base member is moulded to provide fixing and/or supporting means for components of said drive means. By using a one-piece plastics moulding which has all the key positions located on it the necessity to have accurate iocations on a number of separately assembled units as is required in prior art devices is avoided.

The base member is also preferably moulded to form a cable grip for holding the electric cable for supplying power to the motor. Preferably, the cable grip includes separate resilient means for engaging the electric cable and said resilient means may be interchangeable such that cables of different sizes may be reliably held.

The housing may be provided with a slot through which a projecting member, such as a projecting arm or lug, extends. This projecting member is coupled to the valve spindle and is arranged to slide within the slot upon rotation of the valve spindle to thereby provide a visual indication of the position of the valve member.

In an embodiment the base member is provided with at least two upstanding pillars on which a gear plate is supported. These pillars are preferably made of plastics material and integrally formed with the base member. The gear plate is formed with a first hole arranged to receive the valve spindle. Preferably this first hole provides an upper end bearing for the valve spindle. The electric motor is supported by the gear plate which has a second hole through which an output shaft of the motor extends. Accordingly, the gear plate accurately locates the valve spindle and the motor output shaft relative to one another.

In known manner the motor output shaft carries a driving pinion which engages with teeth provided on a quadrant rotationally fixed to the valve spindle.

If required the gear plate may also be provided with one or more downwardly extending lugs mounted to have a degree of resilience and arranged to be contacted by the quadrant as it moves towards its end position(s) to absorb the momentum transmitted to the quadrant by the movable parts and thereby protect the motor, particularly the gear train of the motor, against shock.

The control valve is preferably provided with a manually operable lever for moving the valve member This facility is particularly useful when a central heating system is being commissioned as it enables the valve member to be manually positioned to provide communication between the hot water inlet port and the radiator supply port.

Where the valve is of the spring return type it is necessary to lock the lever in place against the action of the spring return means.

In an embodiment the manually operable lever is formed of two arms, the first arm being coupled to the valve spindle and the second arm being telescopically arranged relative to the first arm.

The second arm projects through a slot provided in the housing and is arranged such that when pressure is applied to the second arm to slide it along the slot and move the valve member by way of the first arm towards one of its predetermined positions, the pressure also telescopes the second arm within the first arm to automatically lock the lever in position. Preferably, the first arm is mounted for movement with the quadrant such that further movement of the quadrant towards its end position associated with said one predetermined position of the valve member causes the second arm to be extended relative to the first arm to thereby automatically unlock the lever.

Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a longitudinal section through a motor driven control valve of the present invention, the section having been taken on the line A-A of Figure 2, Figure 2 shows an end elevation of the control valve of Fig. 1 with the valve unit shown in cross section.

Figure-3 shows a section through drive means of the control valve taken along the line B-B of Figure 1, and Figures 4a to 4d show a manually operable lever of the drive means in several positions.

Figure 1 shows a longitudinal section through a motor driven three port control valve of the spring return type having a valve unit 1 and a control and drive unit 2 supported by the valve unit 1. The valve unit 1 comprises a valve body 3 defining an inlet port 4 and two outlet ports 5 and 6. The body 3 is conventionally made of metal, and, for example, is a brass hot pressing. The valve body 3 is provided with three integrally formed, spaced upstanding pillars 10, 11 and 1 2 which support the control and drive unit 2 The inlet port 4 is connected to a boiler (not shown) for supplying hot water. The outlet port 5 is connected to a domestic hot water system and the outlet port 6 is connected to a central heating system.The valve unit 1 has a valve member in the form of an eccentrically mounted rubber ball 7 which is movable such that it may be seated against a valve seat 8 of the outlet port 5 or against a valve seat 9 of the outlet port 6. Thus, the ball 7 may selectively block either the port 5 leading to the hot water system or the port 6 leading to the central heating system. The ball 7 may also be positioned in a mid-position as shown in Figure 1 in which the inlet port 4 is connected to both of the outlet ports 5 and 6. The ball 7 is normally held against the valve seat 9 by spring pressures such that it normally blocks the port 6 leading to the central heating system.

As can be seen in Figures 1 and 2 a horizontally extending shaft 13 extends through the ball 7 centrally thereof. This central shaft 1 3 is fixed to a vertically extending valve spindle 1 5. The valve spindle 1 5 is arranged eccentrically relative to the ball 7. It will be appreciated that rotation of the spindle 1 5 will move the ball 7 between a first end position against the seat 9 and a final end position against the seat 8. The central pillar 12 of the valve body 3 is hollow and provides a guide passage for the spindle 1 5. O-rings 1 6 are provided around the spindle 1 5 to seal this guide passage against leakage from the valve unit 1.

The control and drive unit 2 includes an electric motor 1 7 for rotating the valve spindle 1 5 as will be described below such that the ball 7 is moved from its position against seat 9 to its final end position against seat 8. This motor 1 7 is housed within a casing of plastics material comprising a moulded base member 18 and a removable cover 19. The base member 1 8 is a moulded one-piece member having fixing and/or supporting means for components of the drive and control unit 2 integrally formed therewith as will become apparent. The base member 1 8 has a peripheral upstanding wall 47 such that it is shaped like a tray. The moulded base member 18 has a bore 20 extending therethrough for receiving the top end portion 21 of the central pillar 12 of the valve body 3. This top end portion 21 has a reduced diameter as compared to the rest of the pillar 12 whereby an annular shoulder 22 is defined on which the base member 1 8 is supported.

As is clearly shown in Figure 1 the reduced diameter end portion 21 of the pillar 12 only extends within the thickness of the base member 1 8 and does not project into the casing of the control and drive unit 2. The other two pillars 10 and 11 of the valve body 1 abut the bottom surface of the base member 18. These pillars 10 and 11 are located at opposite ends of the valve body 3 to provide maximum stability for the casing with the minimum of manufacturing accuracy.

Each of the pillars 10, 11 is drilled to receive a screw 23 which also extends through a corresponding bore 24 provided in the base member 1 8 whereby the base member 18 is fixed to the valve body 3.

In use hot water flows through the valve unit 1 and accordingly the valve body 3 becomes heated.

In the construction illustrated in the Figures the base member 18 insulates the inside of the casing and hence the motor 1 7 from the valve body 3.

This has the important advantage that the life of the motor 1 7 is increased as it is able to operate at lower temperature than in known control valves.

The base member 1 8 is formed to have two spaced upstanding hollow pillars 25. Each of these pillars has a reduced diameter upper end portion 26 arranged to engage in a suitably positioned hole 27 provided in a gear plate 28. Accordingly, the gear plate 28 is located by and supported on the pillars 25. The gear plate 28 is also provided with a hole 29 in which a reduced diameter upper end portion 30 of the valve spindle 1 5 is engaged.

The hole 29 provides an end bearing for the spindle 15.

The gear plate 28 is-firmly fixed on each of the pillars 25, and thereby firmly supported relative to the base member 18, by way of a respective screw 31 which extends into each pillar 25, which is provided with an internal thread. The gear plate 28 supports the motor 17 and has a further hole 32 (Figure 3) through which the output shaft (not shown) of the motor 1 7 extends.

In a known manner, the output shaft of the motor 1 7 carries a driving pinion (not shown) which engages with teeth 33 provided on a metal quadrant 34 (Figure 3).-This quadrant 34 is rotationally fixed to the valve spindle 1 5 by way of a metal sleeve 70 and is supported by a plastics material sleeve 35 which surrounds the valve spindle 15. This sleeve 35, which insulates the valve spindle 15 from the interior of the casing, is rotationally fixed to the valve spindle 1 5 by the metal sleeve 70. The sleeve 35 is supported on a circlip 86, which engages in a corresponding annular groove formed in the valve spindle 1 5. The sleeve 35 is integrally formed with a horizontally extending arm 36 telescopically receiving a further arm 37 also of plastics material.The arms 36 and 37 together form a manually operable lever including a lost motion mechanism for manually opening the port 6 as will be described further hereinbelow.

The quadrant 34 has two diametrically opposed downwardly extending arms 38, only one of which can be seen in Figure 3, to which one end of a respective spring 39 is attached. The other end of each spring 39 is connected to a suitable projection 40 pressed in the base member 1 8. The springs 39 normally bias the quadrant 34 into its initial end portion in which the valve member 7 is seated against the valve seat 9.

Power for the electric motor 17 is supplied by way of an electric cable 41, a circuit board 42 and switch means 43. The base member 1 8 is formed with suitable supporting means for the switch means 43 which, in turn, support the board 42.

Both the central heating system and the hot water system preferably include a thermostat (not shown) for controlling the operation of the valve.

Normally, the valve member 7 is held against the seat 9 by way of the springs 39 which hold the quadrant 34 in the position illustrated in Figure 3.

However, when the thermostats indicate that hot water is required by the central heating system the electric motor 1 7 is energised by way of the circuit board 42 and of the switch means 43 such that the output shaft thereof is rotated. The driving pinion carried by the motor output shaft thereby rotates and rotates the quadrant 34 in the anticlockwise direction as shown in Figure 3. This rotation of the quadrant 34 rotates the valve spindle 15 such that the ball 7 is moved out of contact with the valve seat 9 to its final end position against the valve seat 8. The motor will hold the ball 7 against the seat 8 against the action of the springs 39 so long as it is energised.

When the motor 1 7 is subsequently switched off the springs 39 return the quadrant 34 to its initial end position shown in Figure 3 and thereby rotate the valve spindle 1 5 such that the ball 7 is returned to its first end position against the seat 9.

If the thermostats indicate that hot water is to be supplied to both the central heating system and the hot water system the motor 1 7 is operated to move the ball 7 from seat 9 towards seat 8 and then locked to hold the ball 7 in its mid-position shown in Figure 1 in which tho inlet port 4 is connected to both of the outlet ports 5 and 6.

One of the downwardly extending arms 38 of the quadrant 34 is attached to an arm 44 (Figure 3) carrying a projecting tab 45 which projects within a groove 46 provided in the upstanding peripheral wall 47 of the base member 18. Both the arm 44 and the tab 45 are moved upon rotation of the quadrant 34 and hence of the valve spindle 1 5 such that the tab 45 provides a visual indication of the rotation of the valve spindle 1 5 and hence of the position of the valve member 7.

The base member 1 8 is shaped to provide an integral cable grip for the electric cable 41. As can be seen in Figure 3, the peripheral wall of the base member 18 is provided with a groove 48 through which the cable 41 extends. The wall of the base member 1 8 is also provided with a projection 49 having serrations 50 on the free surface thereof for gripping the cable 41. The cable 41 is pressed against the serrations 50 by means of a separate, removable plastics material strap 51 which is press fitted into a groove 52 formed in the wall of the base member 1 8. It will be appreciated that by changing the strap 51 for a strap of a different length different thicknesses of cable 41 can be reliably retained relative to the base member 1 8 by the cable grip.

As has been made clear above a manually operable lever 36, 37 is provided so that the valve member 7 may be moved manually away from its first end position against seat 9. As can be seen in Figure 2 the upstanding peripheral wall at one end of the base member 18 is provided with a slot 53 through which the arm 37 of the lever extends.

This slot 53 extends substantially horizontally and comprises a first portion 54 of sufficient depth to enable the arm 37 to slide therealong, and an adjacent increased depth portion 55. The two portions 54, 55 of the slot define a shoulder 56 therebetween. Several positions of the manually operable lever 36, 37 are shown in Figures 4a to 4d. In the position illustrated in Figure 4a the quadrant 34 is being held in its initial end position by the action of the springs 39 such that the valve member 7 is in its first end position against the valve seat 9. As can be clearly seen in Figure 4a the arm 36 is shaped to define a groove 57 in which the inner end portion of the arm 37 is slidable. This inner end portion of the arm 37 carries a downwardly extending projection 59 engaged in an elongated slot 58 provided in the base of the groove 57 of the arm 36.In the position shown in Figure 4a the arm 37 is in its extended position relative to the arm 36 and is held relative to the arm 36 by the engagement of the projection 59 against one end of the slot 58.

The arm 37 is also located as it abuts against one wall of the groove 57. In this position the arm 37 extends through the portion 54 of the slot in the base member 18 and as can be seen in Figure 3 projects relative to the base member. It will be appreciated that the projection 59 prevents the arm 37 being removed from the valve. In addition, a locking tab 62 of the arm 37 prevents the arm 37 being slid into the arm 36 as it engages against the external surface of the base member 1 8 surrounding the slot portion 54.

As can be clearly seen in Figure 4a the arm 37 is shaped to have a head portion 60 provided with a serrated surface 61 which forms a finger grip.

The arm 37 is also provided with a shaped projection 63 which defines a groove with the locking tab 62.

If it is required to manually move the valve member 7 away from the valve seat 9, for example when initially filling the central heating system, the arm 37 is moved along the slot 53 by applying pressure to the head 60. It will be appreciated that movement of the arm 37 will cause movement of the arm 36 because of their interengagement and accordingly will rotate the sleeve 35 thereby rotating the valve spindle 1 5 and moving the valve member 7. Once the lever 37 has been moved into the increased depth portion 55 of the slot 53 the locking tab 62 no longer prevents sliding of the arm 37 and the pressure applied to the head 60 will cause the arm 37 to be slid relative to the arm 36 within the groove 57 to the position illustrated in Figure 4b.

In the telescoped position shown in Figure 4b the valve member 7 has been moved away from the seat 9. The valve member 7 is held in this open position against the action of the return springs 39 due to the engagement of the shoulder 56 of the slot 53 in the groove of the arm 37 defined between the locking tab 62 and the head 60.

If the motor is now energised to move the ball 7 against the valve seat 8 the quadrant 34 and arm 36 will be moved to the position shown in Figure 4c. However, the end of the slot 53 prevents further movement of the arm 37 and pivoting of the arm 37 relative to the arm 36 as shown in Figure 4c occurs. When the motor has brought the valve member 7 into its final end position against seat 8 the arms 36 and 37 are in the relative position shown in Figure 4d. In this position the arm 37 has been extended relative to the arm 36 by interaction between an inclined surface 73 and a raised end surface 73 of the arm 36. In the extended position of the arm 37 the shoulder 56 is no longer engaged between the locking tab 62 and the head 60.Accordingly, when the motor 1 7 is switched off such that the quadrant 34 returns to its initial position under action of the return springs 39 the arm 37 can be returned to its initial position extending through the slot portion 54.

It will be seen that the manually operable lever 36, 37 includes a lost motion mechanism such that when the arm 37 is pushed hard into the portion 55 of the slot the arm 37 is stopped by the end of the slot 53 in a position in which the ball 7 is not in its end position firmly against the valve seat 8. Accordingly, when the motor is energised the motor moves the ball 7 into firm contact against the seat 8. This lost motion mechanism ensures that manual operation does not cause damage to the motor.

When the motor is energised to move the ball 7 from its first end position against the seat 9 to its final end position against the seat 8 the movable parts have a momentum which must be absorbed in order to protect the motor. In the three port valve illustrated the resilience of the rubber ball 7 is sufficient to absorb this momentum as it engages against the valve seat 8 so that there is not an abrupt stop.

However, in the case of a two port on-off valve or if the valve closure member is in a form which is not capable of absorbing the momentum means should be provided to avoid an abrupt stop of the movable parts to thereby protect the motor. In the embodiment illustrated a cut-out 65 is provided in the gear plate 28 to define a downwardly extending lug 66 which is mounted at one end 67 to the gear plate 28. The lug 66 is positioned such that the quadrant 34 abuts thereagainst as it moves towards its final end position. The lug 66 has a degree of resilience such that it is capabie of absorbing the momentum transmitted to the quadrant 34 by the movable parts as the quadrant 34 abuts thereagainst.

As can be seen from Figures 1 and 2 one end of the cover 1 9 is affixed to the base member 18 by way of a screw 68. At its other end the cover 1 9 is provided with spaced flanges 69 over which tabs 71 formed on the base member 1 8 are arranged to engage.

It will be appreciated from the above description that the base member 1 8 is a one piece plastics moulding which has all the key positions located on it thereby avoiding the need to have accurate locations on a number of separately assembled units as was necessary with known control valves. The gear plate 28 which supports the motor 14 is provided with two accurately positioned holes 27 for location on the plastics pillars 25. Accordingly, the gear plate is accurately located thereby relative to the base member 18. The gear plate also has an accurately located hole 29 for fitting around the upper end portion 30 of the valve spindle 1 5 and a further accurately positioned hole 32 through which the output shaft of the motor extends. The bearing ring which surrounds the output shaft is arranged to accurately fit into the hole 32. Accordingly, the gear plate 28 accurately locates the valve spindle 1 5 and the motor pinion relative to one another.

Although the control valve illustrated is a three port valve, a similar construction to that described herein can also be used for a two port valve.

Furthermore, although the embodiment illustrated includes a rubber ball 7 as the valve member it will be appreciated that any suitable valve member may be provided.

The control valve has been described with particular reference to a central heating system. Of course the control valve described can be used to control fluid flow through any circuit and the valves may be of different sizes and used to control various media.

Claims (21)

1. A motor driven control valve comprising a valve body defining two or more ports, a valve member connected to a valve spindle and arranged within said valve body to be movable between at least two predetermined positions, and drive means, including an electric motor, coupled to said valve spindle for driving said valve member between said predetermined positions, wherein said drive means are mounted in a housing having a base member made of plastics material, said base member being supported on two or more pillars extending from the valve body such that said pillars do not project into said housing.

2. A motor driven control valve as claimed in Claim 1, wherein said valve spindle extends in both the valve body and the housing, ahd wherein the valve spindle extends in the housing within a sleeve of plastics material whereby it is insulated from the interior of the housing.

3. A motor driven control valve as claimed in Claim 1 or 2, wherein three spaced pillars extend from the valve body, one of said pillars being hollow and forming a guide passage for the valve spindle.

4. A motor driven control valve as claimed in Claim 3, wherein the pillars are integrally formed with the valve body, and the other two pillars are spaced from said one pillar and are fixed to the base member.

5. A motor driven control valve as claimed in Claim 4, wherein said other two pillars are located at opposite ends of the valve body to provide maximum stability for the housing and abut the base member.

6. A motor driven control valve as claimed in any of Claims 3 to 5, wherein the hollow pillar has a reduced diameter upper end portion which extends within a bore provided in the base member.

7. A motor driven control valve as claimed in any preceding claim, wherein all of said housing is made of plastics material.

8. A motor driven control valve as claimed in any preceding claim, wherein said housing comprises a removable cover held on said base member.

9. A motor driven control valve as claimed in any preceding claim, wherein the plastics material base member is moulded to provide fixing and/or supporting means for components of said drive means.

10. A motor driven control valve as claimed in Claim 9, wherein the base member is also moulded to form a cable grip for holding the electric cable for supplying power to the electric motor.

11. A motor driven control valve as claimed in Claim 10, wherein the cable grip includes separate resilient means for engaging the electric cable, said resilient means being interchangeable such that cables of different sizes may be reliably held.

12. A motor driven control valve as claimed in any preceding claim, wherein the housing is provided with a slot through which a projecting member extends, the projecting member being coupled to the valve spindle and being arranged to slide within the slot upon rotation of the valve spindle to thereby provide a visual indication of the position of the valve member.

13. A motor driven control valve as claimed in any preceding claim, wherein the base member is provided with at least two upstanding pillars on which a gear plate is supported, the gear plate being formed with a first hole arranged to receive the valve spindle.

14. A motor driven control valve as claimed in Claim 13, wherein said first hole provides an upper end bearing for the valve spindle.

1 5. A motor driven control valve as claimed in Claim 13 or 14, wherein the electric motor is supported by the gear plate which has a second hole through which an output shaft of the motor extends.

1 6. A motor driven control valve as claimed in any of Claims 13 to 15, wherein the upstanding pillars are made of plastics material and integrally formed with the base member.

1 7. A motor driven control valve as claimed in any of Claims 13 to 16, wherein the motor output shaft carries a driving pinion which engages with teeth provided on a quadrant rotationally fixed to the valve spindle and wherein the gear plate is provided with one or more downwardly extending lugs mounted to have a degree of resilience and arranged to be contacted by the quadrant as it moves towards its end position(s) to absorb the momentum transmitted to the quadrant by the movable parts and thereby protect the motor against shock.

18. A motor driven control valve as claimed in Claim 17, further comprising a manually operable lever for moving the valve member.

19. A motor driven control valve as claimed in Claim 18, wherein the manually operable lever is formed of two arms, the first arm being coupled to the valve spindle and the second arm being telescopically arranged relative to the first arm, the second arm projecting through a slot provided in the housing and being arranged such that when pressure is applied to the second arm to slide it along the slot and move the valve member by way of the first arm towards one of its predetermined positions, the pressure also telescopes the second arm within the first arm to automatically lock the lever in position.

20. A motor driven control valve as claimed in Claim 19, wherein the first arm is mounted for movement with the quadrant such that further movement of the quadrant towards its end position associated with said one predetermined position of the valve member causes the second arm to be extended relative to the first arm to thereby automatically unlock the lever.

21. A motor driven control valve substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.