GB2049160A - Air vent regulator - Google Patents

Abstract

An air vent regulator comprising an electric motor (15) arranged to move a vent-operating member (11) along a fixed track (12) in either direction between two extreme positions, in one of which the vent (3) will be open to its greatest extent and in the other of which the vent (3) will either be fully closed or be open to its least extent, the electric motor (15) being driven in response to an input control signal, dependent on the speed setting of at least one electrically-driven fan used in association with the vent to move air through the vent to produce an air flow through a building, room or duct, in a direction appropriate to the required direction of movement of the vent-operating member (11), until the latter has reached one of a plurality of spaced positions, each corresponding to the pre-set position of one of a plurality of pre-adjustable switches (19) or equivalent devices each corresponding to a predetermined relation between the fan speed and the amount of vent opening. The vent may be in a building for housing hens or pigs. <IMAGE>

Description

SPECIFICATION Air vent regulator The invention relates to a regulator for opening and closing an air vent to control the flow of air into or out of a building, room or duct through which the air is drawn by means of one or more fans.

The invention relates particularly, but not exclusively, to a building for housing livestock, for example, laying hens or pigs. In such buildings it is usual for the air to be admitted through a vent in the roof of the building and extracted by electrically-driven fans at low positions in walls of the building.

The electric motors driving the fans are usually controlled by temperature-responsive controllers, whereby the temperature of the air within the building can be maintained within controlled limits. It is desirable that the amount of opening of the air vent should also be controlled in relation to the speed of the fans, whereby when the fans turn faster, the quantity of air which will be drawn through the air vent will be increased, and when the speed of the fans is reduced, the quantity of air through the air vent will be reduced. An object of the invention is to provide an air vent regulator which is automatically operable in response to the speed of one or more fans by which air is moved through the building and the vent.

According to the invention, an air vent regulator comprises an electric motor arranged to move a vent-operating member along a fixed track in either direction between two extreme positions, in one of which the vent will be open to its greatest extent and in the other of which the vent will either be fully closed or be open to its least extent, the electric motor being driven in response to an input control signal, dependent on the speed setting of at least one electrically-driven fan used in association with the vent to move air through the vent to produce an air flow through a building, room or duct, in a direction appropriate to the required direction of movement of the vent-operating member, until the latter has reached a position corresponding to a predetermined relation between the fan speed and the amount of vent opening.

Conveniently, the electric motor is arranged to be stopped when the vent-operating member has reached an appropriate one of a plurality of spaced positions in the fixed track, each position corresponding to a different amount of vent opening and being determined by an appropriate switch or equivalent signal-producing device, hereinafter called "a switch", of a plurality of switches or devices which are adjustable-movable along the track and are arranged to be operated to stop the electric motor when the vent-operating member has reached an appropriate one of said adjustable switches, each of the adjustable switches having been pre-set to a position to give an amount of vent opening corresponding to a particular fan speed.

The adjustable switches are preferably operated by the proximity of the vent-operating member and may for example be solid-state devices operable by the Hall effect.

The regulator is particularly intended to be used with a roof vent of the kind in which a swinging plate suspended on hangers is arranged to be pulled by a cable from a fullyopen position in which the plate hangs freely downwardly below and is spaced from a vent opening to positions in which the plate is swung on the hangers nearer to the vent opening, thereby to restrict the flow area of the latter, the end of the cable remote from the plate being attached to the vent-operating member, whereby the cable is pulled or relaxed to move the plate by movement in the relevant direction of the vent-operating member along the fixed track.

The end of the cable which is attached to the vent-operating member may be formed with a loop which is engaged with a pin pivotally mounted on the vent-operating member between a retaining position in which the pin retains the loop thereon and a release position in which the loop will be pulled from the pin by the weight of the plate, which will then automatically fall to the position in which the vent is fully-open, the pin being arranged to be held in its retaining position by an electro-magnetic device which is normally energised to hold the pin in its retaining position by a holding voltage derived from the electrical supply to the electric motor and to be pivoted to the release position by the weight of the plate pulling the cable on interruption of the electrical supply to the electric motor and consequent cessation of the holding voltage derived therefrom.This cable arrangement is therefore a fail-safe arrangement such that on failure of the electrical supply to the electric motor, the vent will automatically open to its fullest extent.

By way of example, one form of air vent regulator in accordance with the invention is now described by way of example with reference to the accompanying drawing, in which: Figure 1 is a perspective sketch of the vent and the regulator; Figure 2 is an enlargement of a cable release device shown in Fig. 1 drawn to a larger scale and shown in its release position, and Figure 3 is a diagram of an electrical circuit for controlling the electric motor of the regulator.

Referring to Fig. 1, the vent with which this vent regulator is to be used is a vent in the roof 1 of a building. The vent comprises a fixed ridge 2 defining a vent opening 3.

Beneath the vent opening 3, there is a plate 5 which is suspended on hangers 4, of which one only is shown. The plate 5 can be swung from a fully-open position in which the hangers 4 are vertical and the plate 5 is furthest from the vent opening 3 to partly-closed positions of which one is shown in broken lines in which the plate 5 is positioned near to the vent opening 3 and the hangers are inclined.

Where extreme movement of the plate 5 into a fully-closed position is possible, the plate 5 would abut the underneath of the roof members defining the vent opening 3.

The building is provided with electricallyoperated extractor fans (not shown) in the lower parts of its walls and so when the fans are operating, air will be drawn through the vent opening 3 into the building bathe fans in the directions of arrows 6.

The plate 5 is arranged to be swung between its fully-open and its partly-open or closed positions by pulling or relaxing a cable 7. This is guided on pulleys 8 and has a lower vertical portion 9 which terminates in a loop 10 and is attached to a carriage 11, the aforesaid vent-operating member. The carriage 10 is guided on upright rods 12, forming the aforesaid fixed track and is movable along the rods 1 2 by a lead screw 13 engaging a nut located in the carriage 10. The lead screw 1 3 is driven through a gear system 14 by the electric motor 15.

The electric motor 1 5 is energised by the same electricity supply as the fan motors (not shown) or another electricity supply and is controlled by a control box 1 6 which receives an input signal from a fan controller (not shown) which is responsive to the temperature within the building.

An input signal from the fan controller will effect operation of the motor 1 5 and thus the carriage 11 will be driven upwardly or downwardly according to its position at any instant between positions determined by switches 17, 18, 1 9 (as herein before defined) which will stop the motor 1 5 when the carriage 11 reaches the level of one of those switches.

Two of the switches 17, 1 8 are limit switches determining the extreme upward and downward permissible positions of the carriage 11 and the remainder are several intermediate switches 19, in this example six. The switches 1 9 are manually adjustable along a fixed guide 20 and can be clamped in any desired position and, in this example, are of a solid state kind which are operated by the Hall Effect whenever the carriage 11 reaches the level to which any of the switches 1 9 has been set. The switches are connected to control circuits in the control box 16.

Usually the top and bottom switches 1 9 will be moved to positions respectively just below and just above the limit switches 18, 1 7. The top switch 1 9 will stop the motor 1 5 when the carriage has reached the level of the uppermost switch 19, the vent 3, 5 then being open to substantially its fullest extent.

The bottom switch 1 9 will stop the motor 1 5 when the carriage has reached the level of that switch, the vent 3, 5 then being closed to a minimum vent area. The other switches 1 9 are arranged to correspond to desired intermediate positions of the vent 3, 5.

The circuits in the control box 16 are such that when the fan controller gives an input signal corresponding to a particular fan speed and temperature within the building, the electric motor 1 5 will be operated and will drive the carriage upwardly or downwardly, as controlled by the circuits, until the carriage 11 has reached the position of a switch 1 9 corresponding to a predetermined vent opening required for that fan speed. A change in fan speed will again cause operation of the motor 1 5 until it has come to rest level with the appropriate switch 19, corresponding to the required vent opening. The control circuit is described in more detail hereinafter with reference to Fig. 3.

The aforesaid fail-safe device comprises a cylinder 21 mounted on the carriage 11 and rotatable about the longitudinal axis of the cylinder. The cylinder 21 has an arm 22 extending outwardly from it and carrying a disc 23 of soft iron or other magnetic material which is normally held in the position shown in full lines in Fig. 1 and in broken lines in Fig. 2 by attraction against a solenoid 24 which is held energised by a D.C. holding voltage derived from the electric current provided by the supply applied to the electric motor 15. The cylinder 21 has a pin 25 extending from it. The lower end of the cable 9 is wrapped around part of the circumferential face of the cylinder 21 and the loop 10 is placed over the pin 25.When the arm 22 is held in the position shown in Fig. 1, the pin 25 is in its retaining position in which it holds the loop 10 against the pull exerted by the weight of the plate 5. When the electricity supply to the electric motor 1 5 fails and thus the D.C. holding voltage derived therefrom ceases, the disc 23 is no longer held by the attraction of the solenoid 24 and the pull by the plate 5 on the cable 9 causes the cylinder 21 to turn about its axis to the position shown in Full lines in Fig. 2. The cable 9 will therefore become unwrapped from the cylinder 21 and the loop 10 will be pulled off the pin 25. The plate 5 will therefore fall to its lowest position. Thus air will be able to enter through the fully-open vent opening. Therefore its arrangement is a "fail-safe" one in case the fans also fail.

The regulator may be closed by a removable cover indicated at 26 in Fig. 1. The cover is retained by wing nuts and is readily removable to permit adjustment of the switches 1 9 or reconnection of the loop 10 of the cable 9 on the pin 25 after power has been restored following a failure.

The control box 1 6 is provided with switches 28, 29 connected to appropriate circuits to enable automatic or manual operation of the carriage to be selected and when manual operation has been selected to enable the movement to be performed by switching on the motor 15 for operation in an upward or downward sense. Indicator lamps 30 are provided to show which of the switches 1 9 is operative at any instant.

Fig. 3 is a diagram of the electrical circuit for controlling the electric motor 1 5 and, except for the Hall Effect devices, i.e., the switches 19, the components of the circuit are housed in the control box 1 6.

The circuit comprises a first input part shown at the left-hand side of Fig. 3 comprising a voltage dropping resistance network 31 defining reference voltages to each of five (or another number) of Schmidt triggers 32 to which a control voltage from the fan or fans or from a temperature sensor situated in the building or room in which the regulator is located or mounted on the regulator itself is applied at 33. Output signals from the Schmidt triggers 32 are passed through summing diodes 34 to a first input of a comparator 35.

The signal applied at 33 is an analogue signal of low voltage corresponding to the speed of the fan or fans or temperature.

The outputs from the Schmidt griggers 32 are laddered and so a corresponding switched output appears at the summing diodes 34 in response to any given analogue input signal at 33.

The comparator 35 has a second input which receives a signal via a "Sample and Hold" circuit 36 from a second input part of the circuit shown at the right-hand side of Fig.

3. The second input part of the circuit comprises a plurality of Hall Effect or equivalent devices, constituting the aforesaid switches 19, which can be spaced apart in required positions on the fixed gude 20, as shown in Fig. 1. Output signals from the Hall Effect devices 1 9 are applied to another set of Schmidt triggers 37 from which outputs are applied through diodes 38 to the Sample and Hold circuit 36. The Hall Effect devices are also connected directly via diodes 39 to the Sample and Hold circuit and through resistors 40, 41 to outputs 42, 43 respectively of comparator 35.The outputs 42, 43 of comparator 35, which has a null detector, are applied respectively to "MOTOR UP" and "MOTOR DOWN" relays 44, 45 effecting appropriate directional rotation of the motor 1 5. The carriage 11 which is driven upwardly and downwardly by the motor 1 5 carries a permanent magnet indicated at 46 in Fig. 3, which actuates the appropriate Hall Effect device 1 9 with which it comes into registration as the carriage is moved up and down the rods 1 2. The Schmidt triggers 37 are so connected as to provide laddered analogue voltages corresponding to those produced by the Schmidt triggers 32.The Sample and Hold circuit 36 serves to hold the voltage applied therethrough to comparator 35, while the carriage 11 is moving, at the value corresponding to that of the Hall Effect device 1 9 at which the carriage 11 was last stationary.

The regulator operates as follows: Initially the motor 1 5 will be stationary with the carriage 11 at rest and with the magnet 46 thereon in registration with one of the Hall Effect devices 19, giving the correct amount of opening of the vent 3 corresponding to the temperature in the building or room produced by the fan or fans, or fan speed. On a change in temperature or fan speed, comparator 35 will detect a difference between its two inputs and one or other, as appropriate, of the relays 44 and 45 will be operated to effect rotation of the motor 1 5 in the appropriate direction.

The magnet 46 will then move into registration with the adjacent Hall Effect device or devices in succession in the direction of motion thereby altering the amount of opening of the vent 3 until the Sample and Hold circuit 36 passes a voltage signal equal to that received from the diodes 34, then the relay 44 or 45 which was operated will be deenergised, thereby causing the motor 1 5 to stop. The motor 1 5 will then remain stationary and so the vent will remain in its new position to which it has been adjusted by the carriage 11 until there is a further change in temperature or fan speed. Thus as the analogue voltage applied to comparator 35 through the diodes 34 changes, the carriage 11 and hence the vent plate 5 takes up a position commensurate with that change and this is effected in a plurality of steps determined by the number and position of the Hall Effect devices 19.

Although the left-hand part of the control circuit including the Schmidt triggers 32 is connected in a ladder arrangement, the Schmidt triggers may be connected to feed their outputs to relays operative to bring a plurality of fans into operation sequentially.

Claims (7)

1. An air vent regulator comprising an electric motor arranged to move a vent-operating member along a fixed track in either direction between two extreme positions, in one of which the vent will be open to its greatest extent and in the other of which the vent will either be fully closed or be open to its least extent, the electric motor being driven in response to an input control signal, dependent on the speed setting of at least one electrically-driven fan used in association with the vent to move air through the vent to produce an air flow through a building, room or duct, in a direction appropriate to the required direction of movement of the ventoperating member, until the latter has reached a position corresponding to a predetermined relation between the fan speed and the amount of vent opening.

2. A regulator as claimed in Claim 1 in which the electric motor is arranged to be stopped when the vent-operating member has reached an appropriate one of a plurality of spaced positions in the fixed track, each position correspondirig to a different amount of vent opening and being determined by an appropriate switch or equivalent signal-producing device, hereinbefore called "a switch", of a plurality of switches or devices which are adjustable-movable along the track and are arranged to be operated to stop the electric motor when the vent-operating member has reached an appropriate one of said adjustable switches, each of the adjustable switches having been pre-set to a position to give an amount of vent opening corresponding to a particular fan speed.

3. A regulator as claimed in Claim 2 in which the adjustable switches, as hereinbefore defined, are operated by the proximity of the vent-operating member.

4. A regulator as claimed in Claim 3 in which the adjustable switches, as hereinbefore defined, are solid-state devices operable by the Hall Effect.

5. A regulator as claimed in any preceding claim in combination with a roof vent of the kind in which a swinging plate suspended on hangers is arranged to be pulled by a cable from a fully-open position in which the plate hangs freely downwardly below and is spaced from a vent opening to positions in which the plate is swung on hangers nearer to the vent opening, thereby to restrict the flow area of the latter, the end of the cable remote from the plate being attached to the vent-operating member, whereby the cable is pulled or relaxes to move the plate by movement in the relevant direction of the vent-operating member along the fixed track.

6. A regulator as claimed in Claim 5 in which the end of the cable which is attached to the vent-operating member is formed with a loop which is engaged with a pin pivotally mounted on the vent-operating member between a retaining position in which the pin retains the loop thereon and a release position in which the loop will be pulled from the pin by the weight of the plate, which will then automatically fall to the position in which the vent is fully-open, the pin being arranged to be held in its retaining position by an electromagnetic device which is normally energised to hold the pin in its retaining position by a holding voltage derived from the electrical supply to the electric motor and to be pivoted to the release position by the weight of the plate pulling the cable on interruption of the electrical supply to the electric motor and consequent cessation of the holding voltage derived therefrom.

7. An air regulator constructed and arranged substantially as described herein and shown in the accompanying drawings.