Balancing and control valves

Abstract

A combined balancing and control valve suitable for use in a hydronic system is provided, including a chamber enclosing a plug (6, 10, 16, 15), a seat (13) and a cam and pinion mechanism (20-28) for adjusting the separation of the plug (6, 10, 16, 15) and the seat (13). Pressure ports (42, 43) are included for monitoring the rate of fluid flow across the separation. The cam and pinion mechanism provides a motion transformation (20-27) operable by an actuator (28) to control the motion of the valve plug (6, 10, 16, 15). The valve plug motion provides a favorable change in conductance of the valve for a given change in the actuator position. The actuator (28) is calibrated in increments which correspond to incremental changes in the conductance.

Claims

1. A combined balancing and control valve suitable for use in a hydronic system, the valve comprising a chamber enclosing a plug, a seat and an adjustment means for adjusting a separation of the plug and the seat, monitoring means for monitoring a rate of fluid flow across the separation, wherein the adjustment means comprises a motion transformation means operable by an actuator to control a motion of the valve plug, wherein the valve plug provides a favorable change in fluid conductance of the valve for a given change in a position of the actuator, wherein the actuator is calibrated in increments which correspond to incremental changes in the conductance, wherein the actuator comprises a rod operable on linear motion to actuate the motion transformation means to adjust separation of the plug and seat and an associated calibration means emerging from the chamber having a scale visible outside of the chamber and is operable to limit a maximum separation between the plug and seat which can be created by the actuator, wherein the actuator rod comprises a toothed rack portion, wherein the motion transformation means is a pinion engaging with the toothed rack portion, the pinion being fixed to a cam plate defining a cam guide of a cam mechanism, and wherein the cam plate rotates with the pinion to effect movement of a cam follower, the cam mechanism being operable to adjust the separation of the plug and seat, and a housing and a biasing mechanism, the biasing mechanism urging the rod to emerge from the housing.

2. A valve as claimed in claim 1, wherein the calibration means comprises one or more threaded members arranged to block the linear motion of the actuator by a predetermined increment based on a rotation of the one or more threaded members.

3. A valve as claimed in claim 1, wherein the valve plug and seat are arranged in axial alignment with an intended direction of flow of fluid in the system.

4. A valve as claimed in claim 1, further comprising a shaft to which the cam follower is fixed, the shaft being fixedly mounted to the plug, wherein as the cam follower follows the cam guide provided in the cam plate axial movement of the shaft occurs thereby adjusting the separation of the plug and seat.

5. A valve as claimed in claim 1, wherein the plug and the seat are configured such that the fluid conductance is approximately proportional to a movement of the plug.

6. A valve as claimed in claim 1, wherein the plug is capable of partial differential pressure compensation.

7. A valve as claimed in claim 1, further comprising a pressure compensation chamber and an inlet and an outlet, arranged such that fluid pressure is transferred through the pressure compensation chamber to reduce a force required from the actuator to overcome a given pressure difference between the inlet and outlet.

8. A valve according to claim 1, wherein the motion transformation means is located within a path of fluid flow.

9. A valve as claimed in claim 1, wherein the plug is configured to reach a fully closed position at a predefined position of the actuator.

10. A valve as claimed in claim 1, further comprising monitoring means for monitoring a rate of fluid flow through the valve; and calibration means for calibrating the actuator, the calibration means comprising a scale; wherein the monitoring means and the calibration means are together configured to enable a user to calculate the rate of fluid flow through the valve from a reading on the scale and a determination of a differential pressure across the valve.

11. A valve as claimed in claim 1, further comprising a biasing spring to resist axial movement of the plug relative to the seat.

12. A valve as claimed in claim 11, wherein the biasing spring is arranged to urge the valve to open.

13. A valve as claimed in claim 1, wherein the adjustment means is configured to adjust the separation between the plug and the seat continuously between a fully open position and a fully closed position.

14. A valve as claimed in claim 13, wherein the plug includes a resilient sealing means, said sealing means being configured to cooperate with the seat through most of the separation.

15. A combined balancing and control valve suitable for use in a hydronic system, the valve comprising a chamber enclosing a plug, a seat and an adjustment means for adjusting a separation of the plug and the seat, monitoring means for monitoring a rate of fluid flow across the separation, wherein the adjustment means comprises a motion transformation means operable by an actuator to control a motion of the valve plug, wherein the valve plug provides a favorable change in fluid conductance of the valve for a given change in a position of the actuator, and wherein the actuator is calibrated in increments which correspond to incremental changes in the conductance, wherein the actuator comprises a rod operable on linear motion to actuate the motion transformation means to adjust separation of the plug and seat and an associated calibration means emerging from the chamber having a scale visible outside of the chamber and is operable to limit a maximum separation between the plug and seat which can be created by the actuator, wherein the actuator rod comprises a toothed rack portion, wherein the motion transformation means is a pinion engaging with the toothed rack portion, the pinion being fixed to a cam plate defining a cam guide of a cam mechanism, wherein the cam plate rotates with the pinion to effect movement of a cam follower, the cam mechanism being operable to adjust the separation of the plug and seat, and further comprising a shaft to which the cam follower is fixed, the shaft being fixedly mounted to the plug, wherein as the cam follower follows the cam guide provided in the cam plate axial movement of the shaft occurs thereby adjusting the separation of the plug and seat, and front and rear bearing plates, the shaft being received at opposing ends thereof and having a same diameter where the shaft passes through each of the two bearing plates.

16. A valve as claimed in claim 15, wherein the calibration means comprises one or more threaded members arranged to block the linear motion of the actuator by a predetermined increment based on a rotation of the one or more threaded members.

17. A valve as claimed in claim 15, wherein the valve plug and seat are arranged in axial alignment with an intended direction of flow of fluid in the system.

18. A valve as claimed in claim 15, further comprising a shaft to which the cam follower is fixed, the shaft being fixedly mounted to the plug, wherein as the cam follower follows the cam guide provided in the cam plate axial movement of the shaft occurs thereby adjusting the separation of the plug and seat.

19. A valve as claimed in claim 15, wherein the plug and the seat are configured such that the fluid conductance is approximately proportional to a movement of the plug.

20. A valve as claimed in claim 15, wherein the plug is capable of partial differential pressure compensation.

21. A valve as claimed in claim 15, further comprising a biasing spring to resist axial movement of the plug relative to the seat.

22. A valve as claimed in any claim 15, further comprising a pressure compensation chamber and an inlet and an outlet, arranged such that fluid pressure is transferred through the pressure compensation chamber to reduce a force required from the actuator to overcome a given pressure difference between the inlet and outlet.

23. A valve as claimed in claim 15, wherein the adjustment means is configured to adjust the separation between the plug and the seat continuously between a fully open position and a fully closed position.

24. A valve according to claim 15, wherein the motion transformation means is located within a path of fluid flow.

25. A valve as claimed in claim 15, wherein the plug is configured to reach a fully closed position at a predefined position of the actuator.

26. A valve as claimed in claim 15, further comprising monitoring means for monitoring a rate of fluid flow through the valve; and calibration means for calibrating the actuator, the calibration means comprising a scale; wherein the monitoring means and the calibration means are together configured to enable a user to calculate the rate of fluid flow through the valve from a reading on the scale and a determination of a differential pressure across the valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) By way of example an embodiment of the invention will now be further described with reference to the accompanying drawings in which:

(2) FIG. 1A shows a side view of a valve in accordance with the invention in partial cut away view;

(3) FIG. 1B shows a magnified view of the calibration means in FIG. 1A;

(4) FIG. 2 shows a top view of the valve of FIG. 1 in partial cut away view;

(5) FIG. 3 shows the valve in cross section partially through its travel;

(6) FIG. 4 shows an external side view of the valve with an electromechanical actuator attached.

DETAILED DESCRIPTION

(7) The valve of FIG. 1A generally comprises a housing (14, 17) which defines a chamber in which is provided a plug assembly (6, 10, 15, 16) and a seat (13) in axial alignment along the direction of flow of fluid in hydronic system. The plug (6, 10, 15, 16) is carried on a shaft (24) whose axis passes through the centre of the plug (6, 10, 15, 16). The shaft (24) also carries a cam follower assembly (23, 25). A calibration means is provided in the form of assembly (1, 2, 29, 30 and 31) which interacts with a rod (28) which passes through a sealed inlet chamber which is free to slide axially by means of a bearing mounted in the inlet. The rod is adapted to connect to an electromechanical or other controlled drive means (45 in FIG. 4). The calibrated stroke limiting mechanism (1, 2, 28, 29, 30, 31) is provided to adjust the maximum opening of the valve during a balancing procedure.

(8) The rod (28) extends into the chamber in a direction perpendicular to the motion of the plug and parallel with the face of the plug (6, 10, 15, 16) in the form of a toothed portion. The toothed portion engages with a pinion gear (21) which is fixedly mounted by means of pin (26) to a cam plate which incorporates a guide (20) for a cam follower (23). The cam follower (23) is fixedly mounted on the shaft (24) and the pinion gear (21) passes through a slot in the shaft (24) so as not to obstruct its axial movement. As the rod moves axially, the pinion gear (21), through its engagement with the teeth of rod (28) is forced to rotate and the cam plate rotates with it. As the cam plate rotates, the cam follower (23) is forced to travel in the cam guide (20) carrying with it the shaft (24). Movement of the shaft (24) in any direction other than axially is prevented by the housing (14, 17), engagement of the pinion gear (21) in the slot of the shaft (24) and other components. The plug (6, 10, 15, 16), carried on the shaft (24) is also forced to move axially thereby adjusting the separation of the plug (6, 10, 15, 16) and seat (13). The distance over which the plug is caused to travel is measured by a scale provided on the area of the rod which emerges from the chamber. A distance traveled by the rod along the scale corresponds to a pre calculated travel distance for the plug (6, 10, 15, 16). The shaft (24) is assisted to move smoothly by rack bearings (12, 18, 19) which hold the rack portion against the pinion without impeding its linear motion.

(9) Just behind the plug (6, 10, 15, 16) encircling the shaft (24) is a spring (4). The spring (4) is compressed so as to urge the plug (6, 10, 15, 16) and seat (13) to separate.

(10) A chamber is formed between the plug (16) and cover plate (11) which is connected by a series of passages to strategically located points upstream of the plug (16). The pressure in this chamber partially compensates the pressure difference across the valve to reduce the actuation force required to move the plug.

(11) Front and rear bearing plates (5, 22) seal around the shaft (24) at opposite ends separate fluid from air in the chamber. The circumference of the shaft (24) where it passes through each of the bearing plates (5, 22) is equal.

(12) With reference to FIG. 2 it can be seen that the pinion gear (21) is mounted in a rod bearing (34) and follower bearings (36, 37) assist in the smooth travel of the cam follower (23). By means of pin (39) and biasing spring (33), the positioning of the cam plate with respect to the cam follower (23) is biased so as to urge a return of the cam follower (23) to its position as shown in FIG. 1A, and consequently resists downward strokes of the rod.

(13) The pressure differential across the valve is monitored using ports (42, 43) positioned on opposing sides of the chamber. The scale used on the calibration means (1, 2, 29, 30 and 31) is chosen to correlate with a scale used to monitor the differential pressure such that flow rate can be determined from these two readings.

(14) In FIG. 3, two regions of interest are shown with hatching patterns: a pressure compensation chamber (40) and its associated passages which connect to the upstream region of the chamber. Positioning of the passages is selected to give as little force against the actuator as possible while maintaining stability. The mechanism chamber (41) is separated from the fluid and is connected to the air outside of the chamber.

(15) In use, a maximum operational flow is first applied to the valve and by using the combination of the calibration scale and the measured pressure differential at that flow rate, the optimal maximum separation of the plug and seat is identified and the valve adjusted to restrict the maximum separation to that optimum. After which a controlled drive means can operate an actuator to move the valve between a closed position and the optimum maximum opening position in the normal operation of the valve in response to the external control signal.

(16) The following table summarises the referenced components in FIGS. 1, 2 and 3.

(17) TABLE-US-00001 Ref: Label Notes 1, 2 Stroke Limit Used to set the maximum flow Setting 4 Biasing Urges the mechanism toward an open position, Spring helping prevent oscillation 5 Front bearing Includes a seal around shaft 24, separating plate water from air 6 plug screw Attaches two halves of the plug together, capturing the seal 7, 8, 9 Plug Position These parts are used during factory calibration Calibration to ensure that the plug presses against the seat Setting with the correct force at the end of its stroke 6, 10, Plug Two metal pieces are held together with 16, 15 screws, and a resilient seal is held between them 15 Plug Seal Resilient face of plug, which helps with sealing 11 mechanism Keeps water out of mechanism, removable for sealing plate assembly and possible repair 12, 18, Rack Bearing 19 13 Seat Cooperates with plug to create control restric- tion 14, 17 Housing 20 Cam 21 Pinion Connected by a shaft to cam plate 20 22 Rear Bearing Includes seal around shaft 24 separating air Plate from water again, but in the opposite direc- tion: shaft 24 is compensated with respect to the pressure difference between water and air. 23 Follower The cam 20 has a groove which defines the Rod motion of the plug. A follower moves within this groove, and includes a small shaft and a bearing. There are actually two bearings and two cams, but they function as a single cam/ follower pair 24 Shaft Transmits motion from the characterizing mechanism to the plug 25 Follower Connects the follower rod 23 to shaft 24 Shaft Pin 26 Cam Pin Connects the cam to pinion 27 Mechanism Supports bearings for rack and pinion support plate 28 Stem Connects actuator to characterizing mechanism 29, 30, Stroke Limit See 1, 2 above 31 Setting 32 Housing Screw Connects parts of the housing 33 Spiral Bias This component may be deleted in future Spring versions 34 Pinion Rod Bearing 35 Mechanism Support Plate 36, 37 Follower Bearing 38 Mechanism Support Screw 39 Spiral Spring Pin 40 Pressure compensation chamber 41 Mechanism chamber 42, 43 Pressure Monitor differential pressure across the valve ports chamber

(18) While several aspects of the present invention have been described and depicted herein, alternative aspects may be effected by those skilled in the art to accomplish the same objectives. Accordingly, it is intended by the appended claims to cover all such alternative aspects as fall within the true spirit and scope of the invention.