GB1573104A - Control system for external louvres on a building - Google Patents

Description

(54) CONTROL SYSTEM FOR EXTERNAL LOUVRES ON A BUILDING (71) We, W. H. COLT(LONDON) LIMITED, a British company, ot Havant, Hampshire PO9 2LY, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention is concerned with a control system for external louvres on a building.

External louvres are provided on buildings to regulate solar heating of the building and thereby reduce the load on the air conditioning plant in the building during sunny weather enabling the plant to be reduced in size for a given performance.

It is an object of the present invention to provide an improved control system for external louvres on a building.

The present invention is a control system for external louvres on a building, the system comprising a time switch defining first and second periods in each day, a first sensor responsive to sunlight and operative with associated circuitry during the first period to provide a louvre control signal in accordance with the sunlight sensed, and a second sensor responsive to rain and operative with associated circuitry during the second period to provide a control signal to place the louvres in their closed position when rain is sensed.

Preferably, there is provided a third sensor responsive to wind velocity and operative with associated circuitry during the first and second periods to provide a louvre control signal for retracting the louvres when the wind exceeds a preset value.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, the four figures (Figures la, ib, 2 and 3) of which together form a circuit diagram of a louvre control system according to the present invention.

By way of background, it should be understood that the louvres are driven to their various operating positions by motors energised through conventional relay units.

The circuit illustrated controls the energisation of the relay units.

Referring now to the drawing, the circuit is energised from an a.c. mains supply on lines 10 and 11, (Figure la) main and auxiliary transformers 12 and 13, respectively, being connected in parallel across the lines 10 and 11 and respectively energising main and auxiliary power boards 14 and 15. The output from the boards 14 and 15 comprises d.c. on the lines 16 and 17, (Figure Ib) the former being positive with respect to the latter which is earthed at 18. Connected between the lines 16 and 17 are a sun level sensor unit 20, a wind sensor unit 21 and associated control circuitry for the two units 20 and 21 as illustrated.

Connected across the lines 10 and 11 is a signal output circuit 24 (Figure la) includ ing a timeswitch 25 controlling the operation of the louvres on one elevation of the building, in this embodiment the south west elevation, the timeswitch 25 operating to define two periods in each day, namely day and night.

At the start of each daylight period, i.e.

at 5 a.m., the timeswitch 25 operates to close a contact TS/1 and complete a circuit between the lines 10 and 11 through a relay coil TSR. Energisation of the coil TSR causes closure of the normally open contacts TSR/1 to complete a circuit 26 causing the power supply to be connected to the motor relay units connected between the terminals 27, 28 and 29 shown.

The sun level sensor unit 20 (Figure lb) includes a light detection resistor 30 supplied at 5V from the auxiliary power board 15 and connected in series with a parallel combination of potentiometers 31 and 32, the taps on the potentiometers being set at positions corresponding to 20 K lux and 5 K lux respectively.

When the level of sunlight reaches 5 K lux, a sun level detection board 33 energises a relay coil RA, causing the relay's contacts to change over.

The relay contacts, a pair of ganged contacts RA/1 change over to deenergise a relay coil ATD causing its contacts ATD/1 to close, the coil ATD forming part of the anti-hunting circuits 35 shown in Figure 3.

When the level of sunlight reaches 20 K lux, the sun level detection board 33 energises a second relay coil RB to change over its associated contacts RB/1 and RB/2 (Figure 3).

Closure of the normally open contacts RB/2 causes energisation of a relay AP which then completes a hold circuit for itself by closing its normally open contacts AP/1. Also changeover of the contacts RB/1 deenergises a relay coil BTD to close the contacts BTD/I, and energise a relay BPT which, after a five minute delay, completes its hold circuit through the contacts BPT/l.

The louvre positioning circuits, shown in Figure 2, are now brought into play, and for the moment it will be assumed that a manual selection switch 37 is in the "Auto" position.

Energisation of the relay BPT causes, after the five minute delay, the normally open contacts BPT/2 to complete a circuit from the "auto" line 38 of the switch 37, through a diode 39, contacts BPT/2 through relay coil BP. The contacts associated with BP change over, BP/1 opening to ensure that coil ASP 1 remains deenergised, BP/2 closing to complete circuits to coils T2D and DT.

The circuits are traced from the line 38, through line 40, diode 41, closed contacts AP/2 (relay AP in the anti-hunting circuits 35 being energised), line 42, closed contacts BP/2 and thence through line 43 to coil T2D, and through diode 44 and line 45 to coil DT. The coil DT has a variable delay of between + second and four minutes and does not change its contacts until the expiry of the delay during which time the coil D is energised from the line 45 through the contact DT/1 and diode 46. This causes the louvres to be released from their night storage position and driven to their down and closed position.

At the end of the delay on DT, the contacts of DT change over, DT/2 connecting the lines 42 and 45 directly while DT/1 deenergises D and causes energisation of a T2 relay coil, and a relay coil U. The circuit energising T2 is from line 45 through DT/1, line 50, the lower closed contact of BP/3, a push button 51, closed contacts T1D/1, and closed contact D/1. Energisation of T2 and U causes the louvres to move from their closed position to their shielded or tilt position T2.

To summarise the operation of the control circuit so far, when during the daylight period the sunlight first exceeds 20-27 K lux, the louvres are driven from their retracted or night position to their down position, the louvres being closed, and then after a pause the louvres open to their shielded position.

From this situation it is desirable that the louvres move to their open position (i.e. slats horizontal) if the sunlight fades below 16-20 K lux. The control circuit deals with this situation as follows.

When the sunlight falls below 16-20 K lux, the relay coil RB (Figure lb) is deenergised by the detection board 33 causing energisation of the coil BTD (Figure 3). After a delay of say 3-5 minutes, to avoid hunting problems, the contacts BTD/1 open, thus deenergising the coil BPT, opening the contacts BPT/2 and deenergising the coil BP (Figure 2). Contacts BP/2 thus open to deenergise T2D, close contacts T2D/1 and energise coil TlD, T2D having a capacitor connected across it to provide a three second delay in its operation. Contacts BP/1 close to complete a circuit from line 38 through diode 55, contacts AP/3 and DT/3 through coil AP 1. The three second delay in the operation of T2D is to provide a circuit through BP/3 N/C and diode 46 to energise the relay D and drive the louvres to the closed position.

Energisation of T1D completes a circuit to U and to T1 as follows:- line 45, contacts DT/1, line 50, the lower contacts AP1/2, a push button 56, contacts T2D/2 and contacts D/1. Energisation of T1 drives the louvres to their open position with the slats horizontal.

Thereafter during the daylight period the circuit operates the louvres between the open and the tilt positions according as the sun level detection board 33 energises RA only or RA and RB, i.e. as the sun level varies from below 17-20 K lux (but above 5 K lux) to above 20-27 K lux for periods in excess of 3-5 minutes.

If the sun level does drop below 4-7 K lux, RA and RB are both deenergised causing deenergisation of AP.

The result of this is that in the louvre positioning circuits 36, all relay coils are deenergised with the exception of U which is energised from the line 38 by way of line 59, diode 60, closed contacts AP/4, diode 61 and contacts D/2. Energisation of U causes the louvres to be raised to their protected or night position in a housing.

The non-automatic positions of the selector switch 37 produce the indicated position of the louvres, but all positions of the selector switch 37 are overridden by operation of the wind sensor unit 21.

The wind sensor unit 21 (Figure lb) operates to protect the louvres against wind damage, by raising the louvres into their housing when the wind exceeds a critical value. The unit 21 comprises an anemometer 60 with associated circuit board 61 and potentiometer 62 used to set the critical wind speed. When the critical wind speed is exceeded, a signal appears on the line 63 to energise a relay coil W which completes a hold circuit through its contacts W/1 and opens its contacts W/2 to deenergise the signal output circuit causing the louvres to be raised into their housing.

It should be noted that the coil W remains energised until operation of a manual button 64.

Louvres on the facade of a building will clearly become dirty in the course of time and it is desirable to have some way of cleaning them. In the circuit illustrated, this function is performed by a rain sensing unit 70 (Figure la). It should be noted that the supply to the unit 70 is through a line 71 which bypasses the contacts TSR1 but includes normally closed ocntacts TSR2, i.e. the rain sensing unit is inoperative during the daylight period of the timeswitch 25 but operated during the nighttime period.

The unit 70 comprises a rain sensing head 72, a connection box 73 and a timer unit 74 incorporating a cam operated switch 75. When the head 72 detects rain, the timer is operated for five minutes and then closes the switch 75. This connects the terminal 27 to the electrical supply via line 76 and causes the louvres to be driven down to their closed position to be washed by the rain. After 1 hour, the switch 75 is opened to deenergise the terminal 27 and cause retraction of the louvres into their housing.

The wind sensor unit remains in overriding control because of the contact W/2 which if open prevents energisation of the rain sensor unit.

WHAT WE CLAIM IS: 1. A control system for external louvres on a building, the system comprising a timeswitch defining first and second periods in each day, a first sensor responsive to sunlight and operative with associated circuitry during the first period to provide a louvre control signal in accordance with the sunlight sensed, and a second sensor responsive to rain and operative with associated circuitry during the second period to provide a control signal to place the louvres in their closed position when rain is sensed.

2. A control system as claimed in claim 1, including a third sensor responsive to wind velocity and operative with associated circuitry during the first and second periods to provide a louvre control signal for retracting the louvres when the wind exceeds a preset value.

3. A control system for external louvres on a building, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. in excess of 3-5 minutes. If the sun level does drop below 4-7 K lux, RA and RB are both deenergised causing deenergisation of AP. The result of this is that in the louvre positioning circuits 36, all relay coils are deenergised with the exception of U which is energised from the line 38 by way of line 59, diode 60, closed contacts AP/4, diode 61 and contacts D/2. Energisation of U causes the louvres to be raised to their protected or night position in a housing. The non-automatic positions of the selector switch 37 produce the indicated position of the louvres, but all positions of the selector switch 37 are overridden by operation of the wind sensor unit 21. The wind sensor unit 21 (Figure lb) operates to protect the louvres against wind damage, by raising the louvres into their housing when the wind exceeds a critical value. The unit 21 comprises an anemometer 60 with associated circuit board 61 and potentiometer 62 used to set the critical wind speed. When the critical wind speed is exceeded, a signal appears on the line 63 to energise a relay coil W which completes a hold circuit through its contacts W/1 and opens its contacts W/2 to deenergise the signal output circuit causing the louvres to be raised into their housing. It should be noted that the coil W remains energised until operation of a manual button 64. Louvres on the facade of a building will clearly become dirty in the course of time and it is desirable to have some way of cleaning them. In the circuit illustrated, this function is performed by a rain sensing unit 70 (Figure la). It should be noted that the supply to the unit 70 is through a line 71 which bypasses the contacts TSR1 but includes normally closed ocntacts TSR2, i.e. the rain sensing unit is inoperative during the daylight period of the timeswitch 25 but operated during the nighttime period. The unit 70 comprises a rain sensing head 72, a connection box 73 and a timer unit 74 incorporating a cam operated switch 75. When the head 72 detects rain, the timer is operated for five minutes and then closes the switch 75. This connects the terminal 27 to the electrical supply via line 76 and causes the louvres to be driven down to their closed position to be washed by the rain. After 1 hour, the switch 75 is opened to deenergise the terminal 27 and cause retraction of the louvres into their housing. The wind sensor unit remains in overriding control because of the contact W/2 which if open prevents energisation of the rain sensor unit. WHAT WE CLAIM IS:

1. A control system for external louvres on a building, the system comprising a timeswitch defining first and second periods in each day, a first sensor responsive to sunlight and operative with associated circuitry during the first period to provide a louvre control signal in accordance with the sunlight sensed, and a second sensor responsive to rain and operative with associated circuitry during the second period to provide a control signal to place the louvres in their closed position when rain is sensed.

2. A control system as claimed in claim 1, including a third sensor responsive to wind velocity and operative with associated circuitry during the first and second periods to provide a louvre control signal for retracting the louvres when the wind exceeds a preset value.

3. A control system for external louvres on a building, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.