GB2409263A

GB2409263A - Automatic ventilation system

Info

Publication number: GB2409263A
Application number: GB0326101A
Authority: GB
Inventors: Blaise Ford
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-11-10
Filing date: 2003-11-10
Publication date: 2005-06-22
Also published as: GB0326101D0

Abstract

An automatic air extractor (10) comprising an inverter frequency converter (14), with a PID (Proportional Integral Differential Acting) controller (15), configured to vary speed of an electric motor (11) driving a ventilator fan (13), in response to air quality condition monitored by a gas sensor (16) local to fan output, for prompt response to adverse environmental gas odour, such as smoke. Co-operative multiple fan operation is also envisaged, with optional control data link through a common mains supply interface.

Description

c ee - Automatic Extraction System

Background

This invention relates to forced (air) flow ventilators and ventilator fans and is particularly, but not exclusively, concerned with ventilator fan control in relation to ambient conditions in an environment to be ventilated.

A consideration is to run fans only as much, and for as long as necessary to achieve desired conditions and (continuous) air change through flow.

Diverse airborne pollutants and odours can degrade an environment and engender adverse respiratory conditions undermining occupant comfort.

1 0 Wider aspects of the invention embrace refinement in local motor and/or motorised appliance control - for fast and flexible response to work demand change.

Prior Art

Control of ventilation fans by sensed air quality has been addressed in diverse art, including: 1 5 GB2380954 Hamilton; US2002/0078830 Chung; EP1035379 D'Urania; US 5252030 Matsushita Seiko; US 5254035 Matshushita Seiko; DE 3922090 Ruhrgas DE 19855056 Auma Tec GB2354623 Innovative Products KR 2000001876 Samsung What determines 'quality' is variable according to circumstances - with certain prime target criteria, such as airborne smoke pollution.

Statement(s) of Invention

According to one aspect of the invention, a Proportional Integral Differential (PID) controller is coupled to, or is a functional module of, an inverter, and configured to translate control instructions into appliance or device control action, in response to a condition sensed.

A prime device category is an electric motor.

An inverter allows do control of an ac motor running from a consumer mains supply.

The PID controller allows motor speed variation by local condition sensing and ë : .: .: . be: :: :: :: .

e:. :- .:. . .e monitoring.

Gas Sensor In practice, a semiconductor gas sensor can react to various gases, including alcohol vapour, but is particularly sensitive to perceived unpleasant smells, such as attends hydrogen sulphide.

Gas concentrations as low as 1 ppm and up to 1 Oppm can be identified by one and the same sensor.

Gas Differentiation Some differentiation between more and less noxious gases is advantageous for more selective control response - ie inhibiting the same reaction to each and every kind of gas.

Air Quality This allows use as an air quality sensor for air purifiers, deodorizers and controllers for automatic ventilators.

1 5 Background Operation

Operationally, a ventilation fan could run (semi-) permanently at a low speed

background level.

This would entail minimal attendant noise, power consumption and environmental heat loss, sufficient for continual modest air (re-) circulation.

Fans would only be brought (temporarily) into greater effect upon sensing adverse local conditions - in particular offensive odour or smoke.

Further control elaboration and refinement could be imparted digitally through the PID controller.

Supplementary Fan Control Modes Other aspects of the invention allow conversion or adaptation of what would otherwise be simple single speed motors, allowing only'gross' ON-OFF control modes, into more sophisticated variable speed motors, with subtle and progressive speed transitions through local digital control elaboration.

Local Condition Sensing & Fan Control A local fan controller could be coupled to remote fans, for joint, mutually co-operative action.

An overall site map of fan locations, room volumes, local 'hazards', access routes, etc could be stored in logic form and addressed by a fan controller.

:. .. .. .. :..

Secondary Assessment Secondary monitoring or derivative assessment, such as space occupancy levels through respiratory CO2 level detection, could be admitted.

Environmental Mapping Conversely, collective monitoring of multiple individual fan conditions could be used to create a digital map of overall environmental conditions.

Thus, say, extraordinary cooking odour build up could signal need for attention to kitchen conditions.

A record of fan action over time could identify acute condition times and allow pre emptive timed action.

Similarly, with identification of locations susceptible to acute trigger conditions.

ProActive Thus, in say pubs or clubs, fan speed could be increased proactively before peak activities such as kitchen operations, table or dance floor occupancy, etc. in order to obviate sudden and extreme corrective (re-) action.

Otherwise, the start of a cabaret entertainment session might coincide with a noisy and distracting boost to fan speed as diners sat and smoked.

Optimisation of Multiple Fan Operation Extractor fans in the immediate environment of an extreme (cigarette) smoke level (assessed at fan output) could be set to increased extraction speed, but could also delegate' a modest speed increase to fans in adjoining areas with less dense smoke levels, for co-operative combined, even synergistic effect.

In this way, multi-level hierarchical control of multiple extractor fans could be contrived.

Volumetric Containment With a knowledge of individual fan air displacement capacity at different speeds, extraction volumetric (ex) change rates could be matched with overall room volumetric capacity.

This could ensure a desired complete air change in a prescribed period.

Individual or collective fan speed changes could effect rapid extraction without disruptive or uncomfortable draughts.

That is, one fan could feed another, or fans could 'harness' or build upon flows initiated by other fans.

Temporary flow stagnation or reversal might be achieved, even if necessary by fan - reversal, to pool air into less sensitive areas for extraction.

Similarly, sanitised or deodorised air could be substituted promptly for obnoxious smoke-laden extracted air.

Undue and/or prolonged extreme fan speeds and abrupt speed transitions (with attendant motor heating and wear) might thus be avoided - in favour of progressive collective local speed variation.

Encoded Control Data Link Such fan inter-coupling could be through a remote encoded data link.

A hard wired or radio data link could be employed.

Encoded data could also be relayed over a common consumer mains power supply, with appropriate interface isolation and noise interference suppression.

Fan speed adjustment could vary with gas type, according to prioritised hierarchy.

Emergency Fan Over-Boost An emergency 'over-boosted' extraction boost mode could be triggered by adverse smoke levels and/or smoke of a particular character attendant fire smouldering or combustion - albeit without promoting combustion flame air intake.

Smothering & Combustion Inhibition Smothering of fire conditions with combustion inhibiting gas, once occupants have been cleared, might also be contemplated.

Prioritised Control Response Control hierarchy could be contrived - eg respiratory safety in relation to smoke and CO2 levels, prioritised over ancillary hygiene considerations, such as body odours from perspiration or kitchen smells. +++

Embodiment(s) There now follows a description of some particular embodiments of the invention, by way of example only, with reference to the accompanying diagrammatic and (block) schematic drawings, in which: Figure 1 shows an overall layout of an automatic extractor fan; Figure 2 shows remote linkage of a fan to multiple sensors at different location for control interpolation; Figure 3 shows remote data linkage of a fan to multiple sensors through a common . a. .. . . .. en- :e :e.. e.

consumer power supply ring main; Figure 4 shows multiple fan linkage; Figure 5 shows multiple fan linkage through a common power supply; Figure 6 shows more specific circuit detail of Figures 1 through 5.

Referring to the drawings: A ventilator extractor fan 13 is driven by a (say, co-axial) motor 11 run from an ac mains consumer supply 17.

The supply 17 is taken through an inverter 14 (frequency converter), with a PID controller 15.

1 0 The PID control 15 is coupled to a local gas sensor 16 at a fan output stage 22.

Alternatively, sensor 16 can be disposed at fan input.

Sensor 16 can also be powered by inverter 14.

The overall arrangement is configured for variable speed fan operation according to sensed condition.

Essentially, the inverter 14 serves as a frequency converter, with PID controller 15 used to vary speed of an otherwise fixed speed ac fan drive motor 11.

Inverter 14 is infinitely variable - and is not necessarily limited to fractions or multiples of mains frequency.

Thus, motor 11 speed can be varied at will.

Sensor 16 continuously samples 'quality' of air extracted at the outlet side 22 of fan 13.

{A suitable gas sensor is based upon a proprietary Nemoto & Co. Odour Sensor NAP 1 1 AS.} Essentially, a bespoke air quality measuring device, based upon gas sensor 16, links with a dc-to-dc power converter, to match inverter 14 output.

More specifically, a 'condition' control signal received by inverter 14 is between 0 1 0V do and represents sensed air quality.

This is used by inverter 14 against a nominal internal reference datum.

Thus, if sensed air Quality' reduces, PID controller 15 instructs speed up of motor 11 and coupled fan 13 - from a minimum speed, to extract more air and so remove pollutants (eg odours).

:.. .. .. .. - :..

In effect, fan speed is controlled by air quality and therefore (prevailing) need for extraction.

An air quality level to meet Health and Safety regulations could be set and reliably conformed to.

A digital record of compliance could even be kept, by monitoring sensor level and fan action.

Diverse airborne pollutants or odours are detectable, including cigarette smoke, cooking smells, body (perspiration) odour, cosmetics, etc. Envisaged extraction benefits include: Automatic extraction; Noise reduction; Reduced power consumption; Reduced building heat loss; The inverter carries out an ac to ac conversion on the power circuits via an intermediate do voltage and is controlled by low voltage do signals.

Sophistication of local response and control admits extension or linkage to other devices - in particular other extractor fans in a shared environment.

Bottom-Up' Control This reflects a 'bottom-up' or foundation control configuration - allowing expansion based upon cumulative local control capability at each station.

Inverter A so-called inverter generally allows frequency conversion, such as do to ac conversion or vice-versa, with voltage step-up or step-down and/or positive negative polarity split about ground level.

In practice,this can be achieved wholly with solid state electronic switching circuit, without transformer inductance coupling.

Thus, an output transistor stage do chopping pattern gives a variable frequency and voltage output effect.

Generally, relatively low voltage do is used for control - aside from an intermediate do 'high' in the inverter.

Relatively high mains voltage ac is readily available through the consumer power supply network for motor drive.

An inverter plays a useful role in allowing both functions to be achieved from a common supply.

. . .. ... ..

. --e . e:. . -he PID Controller Generally, a so-called Proportional Integral Differential (PID) acting controller reacts to a control signal faster than, say a PI controller - and without error signal in static conditions.

A control (trigger) signal might represent a departure or error factor from a desired reference level or threshold.

A sudden step-change can thus be followed by a prompt initiating spike and steep ramp adjustment.

Control Data via Mains Supply 1 0 Relatively low voltage do control data signals associated with a PID controller can be relayed through an encoding interface through a common relatively high (1/2.5 hundred) ac voltage mains supply, to other devices or local device controllers.

Figure 3 reflects a formative level of data link to multiple sensors for different conditions and/or locations for relay to a common PID controller.

1 5 Figure 5 reflects both multiple sensor and motor link from a PID control of at least one motor.

The respective PID controllers of each motor could be similarly linked.

Inter-linkage of appliance modules through a consumer ring main supply has been achieved in diverse ways, such as for example: EP0022232 Fus Fritz ES2120904 Technologico Robotiker Centro GB1500891 Gen Electric GB2174273 Verran Micro-Maintenance GB2227453 Alcatel Business Systems DE10119039 Seimens DE19850050 ABB Research EP0892541 Deutsche TeleKom EP0981188 Ascom Systec EP1073211 Polytrax Inf Technology and devices of Comfort Home Controls.

Detailed Circuitry Figure 6 reflects detailed circuitry, with prime elements and operational criteria.

In practice, the PID controller 15 and inverter 14 can be closely integrated, as reflected in Figure 6.

. .. .. .. .. . - e Inverter drive unit (ac mains) power 17 connections are isolated from low do voltage control connections to air quality sensor 16.

Mix and Match Features Features indicated may be selectively mixed and matched in diverse variants as appropriate - albeit it is not feasible to show every such combination.

Bracketed Claim Features Expressions in brackets, vis { ... } in the appended claims are for ease of reference, as with associated numbering, and as such form no part of claim scope.

Component List 10 automatic extractor fan 11 fan motor 1 3 fan 1 4 inverter PID controller 1 5 1 6 gas sensor 17 ac mains power supply 1 8 supplementary sensor 19 supplementary sensor connected via mains 2 0 21 mains 22 fan output 24 fan output

Claims

. . . . ..

ë.. e Claims 1. {PID Controller + Inverter} A device control comprising a Proportional Integral Differential (PID) controller, coupled to an inserter, and configured to translate control instructions into appliance or device control action, in response to a condition sensed.
2. {Variable Speed Electric Motor} A device control as in Claim 1 configured for electric motor control and wherein an inverter allows variable speed control of what would otherwise be a fixed speed motor when run from ac mains power.
3 {Local Condition Sensing} A device control as in either preceding claim, wherein the PID controller allows motor speed variation by local condition sensing and monitoring.
4. {Gas Sensor} A device control as in any preceding claim, using a semiconductor gas sensor reactive to various gases, including alcohol vapour, but is particularly sensitive to perceived unpleasant smells, such as attends hydrogen sulphide.
5. {Gas Concentration} A device control as in Claim 4, in which gas concentrations as low as 1 ppm and up to 1 Oppm can be identified with one and the same sensor.
6. {Gas Differentiation} A device control as in any preceding claim, allowing differentiation between more and less noxious gases for more selective control response - ie inhibiting the same reaction to each and every kind of gas.
7. {Air Quality Sensor} A device control as in any preceding claim configured for use as an air quality sensor for air purifiers, deodorizers and controllers for automatic ventilators :.. .. e. .. .e:..
8. {Illustrated Embodiments} A device control substantially as hereinbefore described, with reference to, and as shown in, the accompanying drawings.
9. {Automatic Extractor Fan} An automated extractor fan using a device control as in any preceding claim.
10. {Air Quality Extractor Fan Control} An automated extractor fan as in Claim 9, with an air quality sensor at fan output dictating fan speed.