GB2088250A

GB2088250A - Electrostatic air cleaners

Info

Publication number: GB2088250A
Application number: GB8037783A
Authority: GB
Original assignee: BURGESS MANUFACTURING AIR CLEA
Current assignee: BURGESS MANUFACTURING AIR CLEA
Priority date: 1980-11-25
Filing date: 1980-11-25
Publication date: 1982-06-09

Abstract

An electrostatic air cleaner unit suitable for fitting in a vehicle ventilation and heating system. The unit includes an optional inlet filter (10) behind which is located a positively charged ionizer (38). Airborne particles passing through the ionizer are positively charged and are attracted to the earth potential plates in a stack of alternately positive charged and earth potential plates (18). The cleaned air passes through a negatively charged screen (20) and thence through an even more negatively charged ionizer (22). The air is drawn through the unit by a fan (78) located in an exit duct (76), and a heater element (80) is located therebeyond for controlling the temperature of the air before it enters the vehicle. The inlet to the air cleaner unit can be supplied with a mixture of external fresh air and re-circulated air. The positive ionizer is formed by a stretched conductive wire located within an insulating frame (38) itself mounted on extended earthed plates of the stack (18) of alternately positive charged and earth potential plates. <IMAGE>

Description

SPECIFICATION Improvements in and relating to the construction of electrostatic air cleaners Field of Invention This invention concerns electrostatic air cleaners particularly but not exclusively for use in passenger compartments of motor vehicles, railway carriages, aeroplanes and the like.

Background to the Invention It is known to ventilate the interior of a passenger compartment for example a motor vehicle such as a private motor car or passengercarrying vehicle such as a bus or train or aeroplane, by providing air inlets in a forward position on the vehicle and either relying on the air flow produced by forward movement of the vehicle or by producing forced circulation, to cause air to enter the passenger compartment and after passing therethrough to exist from ventilation apertures towards the rear of the vehicle, as the vehicle moves in a forward direction. This ensures that there is a continual air change within the vehicle so as to maintain fresh air in the compartment.

Whilst a certain degree of filtering can be provided to remove airborne particles, in practice the degree of filtering has hitherto been minimal since any conventional filtering tend to increase the resistance to air flow into the compartment which requires more power to be expended in circulating the air into the compartment. The result is that in congested areas and cities considerable volumes of contaminated air can be drawn into the interior of a vehicle and it is an object of the present invention to provide an improved cleaning device for removing airborne particles from the air entering a passenger compartment.

The Invention According to one aspect of the present invention a device for removing airborne particles from the air within a passenger compartment comprises a housing having an air inlet and an air outlet, fan means for drawing air into the inlet and causing it to exhaust through the outlet and between the fan and the outlet an electrostatic air cleaner, comprising a positive ionizer, a particle collecting cell, a negatively charged screen and a negative ionizer, and associated therewith a power supply for providing EHT.

The latter may be located within the housing or alternatively may be located in a separate housing adapted to be connected to the electrical system of the motor vehicle and to the electrostatic air cleaner.

According to a preferred feature of this aspect of the invention the unit is adapted to be mounted on the dashboard of a vehicle and has a flying lead connection adapted to be fitted into the car lighter socket conventionally fitted on the motor vehicle dashboards.

According to another aspect of the present invention, an electrostatic air cleaner comprising a housing having an air inlet and an air outlet and located therebetween a positive ionizer, a particle collecting cell, a negatively charged screen and a negatively charged ionizer and the housing is located in the air intake to the interior of the motor vehicle in the conventional vehicle ventilation system. The power supply for providing the various potentials for the electrostatic air cleaner may derive its power from the motor vehicle electrical system and is conveniently housed adjacent to the electrostatic air cleaning unit to reduce the number of high voltage connections required.

According to this second aspect of the invention, no additional fan means is necessary (although it may be provided if desired) since the through flow of air into the motor vehicle through the ventilation system provides the necessary air flow through the air cleaner unit.

In apparatus incorporating either aspects of the invention, additional filters may be provided to remove particles from the air flow and preferably such additional filters are provided at the air inlet to the electrostatic air cleaner unit so that very large particles are eliminated before they reach the electrostatic air cleaner. This is found in practice to extend the useful life of the air cleaner and preferably the filter units are disposable elements which can be readily replaced.

The invention will allow the interior atmosphere of a motor vehicle to be freshened and will help to reduce accidents by allowing the driver to remain more alert and more aware of changing conditions.

In a preferred embodiment of the invention an electrostatic air cleaner unit is located at a junction between an air intake from an air vent at the front of a motor vehicle and an air intake for recycling air from the interior of the car and mixing it with the air taken from the outside, the combined air mixture being supplied to the inlet of the electrostatic air cleaner and fan means is located beyond the air cleaner to draw the air mixture through the air cleaner and to exhaust the cleaned mixed air through a heater unit into the interior of the car.

The heater unit is preferably controllable in known manner so as to control the temperature of the air forced into the interior of the car.

The heater unit may itself form part of an air conditioning unit so that the temperature of the air can be adjusted both up or down and the humidity of the air can also be adjusted if required.

References to a motor vehicle hitherto are not intended to limit the invention to such application and the invention is equally applicable to any passenger carrying compartment.

In the Drawings Fig. 1 is a layout diagram showing diagrammatically the different parts of an electrostatic air cleaner to be incorporated into a motor vehicle, Fig. 2 is a plan view of the air cleaning cell which is formed from a plurality of parallel conductive plates alternate ones of which are at high positive potential and the others are held at earth potential, Fig. 3 is a plan view of one of the nine plates which are charged positively in the cleaning cell, Fig. 4 is a plan view of one of six plates which are held at earth potential in the cleaning cell, Fig. 5 is a plan view of an enlarged earth potential plate of which there are four in the air cleaning cell, Fig. 6 is a plan view of an ionizer which is adapted to be fitted on the four extended earth potential plates in the cleaning cell shown in Fig. 2, and Fig. 7 is a side view in cross-section of an electrostatic cleaning cell fitted into the ventilation and heating system of a motor vehicle.

Detailed Description of Drawings The diagrammatic view of Fig. 1 illustrates the basic constituent parts of an electrostatic air cleaner. Item 10 comprises a filter mesh for removing large particles from air which flows through the filter in the direction of arrow 1 2.

Item 14 comprises a positively charged ionizing electrode in the form of a stretched conductor situation between parallel earthed plates one of which is denoted by reference numeral 1 6.

Item 1 8 comprises a stack of alternately positively charged and earth potential plates of which some of the earth potential plates are extended to form the earth potential plates 1 6.

The stack 1 8 are supported in a parallel spaced array and particles of dirt and dust and smoke etc., supported by the air stream which are positively charged by the ionizer 14 are attracted to the earthed plates.

Beyond the cleaning cell 1 8 is located a negatively charged screen or mesh 20 and beyond that a further even more negatively charged ionizer 22. The purpose of th items 20 and 22 is to neutralize any positive charge remaining in the air stream passing from the air cleaner unit and will also introduce into the air stream negative ions which are acknowledged to be beneficial.

Fig. 2 illustrates how the plates in the stack 1 8 are arranged and from this it will be seen that there are four extended plates which correspond to plates 1 6 shown in Fig. 2 which are labelled 16, 1 6', 16" and 16"' respectively. These are all held at earth potential and are electrically connected to alternate ones of the intermediate plates forming the stack generally designated 1 8. In between these earthed plates are located a second array of plates which are all electrically connected to a connector 24 which is held at high positive potential typically 4000 volts.

To facilitate the interconnection of the plates, one corner of each of the plates is extended and Figs. 3, 4 and 5 illustrate the different plates making up the stack shown in Fig. 2. In Fig. 3 is shown one of the intermediate positively charged plates and this is designated by reference numeral 26. The connecting spigot 28 is connected to the conductor 24 as shown in Fig. 2.

In Fig. 4 is shown one of the intermediate earth potential collector plates generally designated by reference numeral 30 having a connecting lug 32 at one corner. These are connected via a conductor 34 to the extended electrode plates 1 8 each having a corner connecting lug 36 (see Fig. 5).

The extended plates 1 6, 1 6' etc. are fitted into a frame made of electrically insulating material typically a plastics material which is illustrated in Fig. 6. The frame is designated by reference numeral 38 and is provided with four pairs of parallel slots one pair of which is shown at 40 and 42. Into these pairs of slots are fitted the extended sections of the earthed electrodes 1 6, 1 6', 1 6" and 16"' and between the extended electrodes 1 6, 1 6' etc. extends a stretched wire 44 which is anchored at 46 and 48 and extends through bushes 50, 52, 54 and 56 externally of apertures one of which is designated by reference numeral 58 formed in the walls of the frame 38.The wire 44 is housed within sleeves shown in dotted outline at 60 and 62 and the sleeves are preferably formed from electrically insulating material such as rubber or plastics or a combination thereof. The natural resilience of the sleeves 60 and 62 may be sufficient to provide the tension for keeping the wire 44 taut but if not spring means may be located at one or both ends or at each point where it passes through the frame 38 so as to further tension the wire 44 and keep it straight and parallel between the plates 1 6, 1 6' etc.

Fig. 7 is a cross-section through a preferred embodiment of the invention incorporating the constructional features of Figs. 2 to 6. The stack of plates forming the cleaning cell generally designated 1 8 is located within a housing 64 which itself is located within or forms an integral part of an air duct 66 which communicates at one end with an air intake via a hose 68 to receive fresh air from outside a motor vehicle and with a second air intake via a hose 70, the second air intake being located within the motor vehicle to allow air from within the vehicle to be recycled.

The housing 64 is open at its two ends 72 and 74 respectively and air can flow from the hoses 68 and 70 through the air cleaning unit to a reduced section duct 76 in which is located a fan 78. The fan is driven in a manner so as to draw air through the housing 64 to exhaust it through a heater element 80 for warming the air.

Within the unit is located an inlet filter 10 conveniently in the form of a grille or mesh and behind this is located the ionizer assembly mounted within the frame 38 as illustrated in more detail in Fig. 6.

The frame 38 is supported on the extended electrodes of the stack generally designated 1 8 and an earth connection to all the plates which have to be held at earth potential is made through a contact and conductor generally designated 82.

Beyond the cleaning stack 1 8 in the direction of airflow, is located a negative screen 20 and beyond that a negative ionizer 22.

Connections to the positive ionizer, the positively charged plates in the stack 18, the negative screen 20 and the negative ionizer 22 are made through conductors 84, 86, 88 and 90 respectively which extend from and are supported by an EHT power supply 92. The latter includes provision for controlling the potential of the positive ionizer in relation to the current drawn from the EHT power supply by the positive ionizer so that the production of ozone is minimised.

The conductors 84 to 90 inclusive and the earth connection via the conductor 82 are typically plug-in connectors or spring contacts so that the various parts of the air cleaner unit within the housing 64 can be removed without the need for undoing electrical connections.

Typically the positive ionizer conductive wire 44 is maintained at a positive potential of approximately 7000 volts, the positively charged plates in the stack 1 8 are maintained at approximately 4000 volts, the negative screen is maintained at a negative potential of -3500 volts and the negative ionizer is maintained at a negative potention of -4500 volts. The above potentials are all related to earth potential.

Claims

1. A device for removing airborne particles from the air within a passenger compartment comprising housing having an air inlet and an air outlet, fan means for drawing air into the inlet and causing it to exhaust through the outlet and between the fan and the outlet, an electrostatic air cleaner comprising a positive ionizer, a particle collecting cell, a negatively charged screen and a negative ionizer, and associated therewith a power supply for providing EHT therefor.

2. A device as claimed in claim 1 in which the EHT power supply is located within the housing.

3. A device as claimed in claim 1 in which the EHT power supply is located in a separate housing.

4. A device as claimed in 1, 2 or 3 in which the power supply is adapted to be connected to the electrical system of a vehicle containing the compartment.

5. A device as claimed in any of claims 1 to 4 in which the housing is adapted to be mounted on the dashboard of a motor vehicle and has a flying lead connection adapted to be connected into the motor vehicle electrical system.

6. A device as claimed in claim 5 in which the flying lead connection is adapted to be fitted into a cigar lighter socket.

7. An electrostatic air cleaner comprising a housing having an air inlet and an air outlet and located therebetween a positive ionizer, a particle collecting cell, a negatively charged screen and a negatively charged ionizer, the housing being located in the air intake to the interior of a passenger compartment which forms the air intake of a conventional ventilation system for the compartment.

8. A device as claimed in claim 7 further comprising a power supply therefor which derives its power from the vehicle electrical system and is housed adjacent to the air cleaning unit to reduce the number of high voltage connections required.

9. A device as claimed in claim 7 or 8 ih which the air cleaner includes further fan means operable independently of any fan means in the ventilation system of the vehicle.

10. A device as claimed in any of the preceding claims further comprising mechanical filters adapted to remove particles from the air flow through the unit.

11. A device as claimed in claim 10 in which any additional mechanical filters are provided in advance of the electrostatic air cleaning unit (in the direction of air flow therethrough) so that large particles of airborne dust etc., are removed from the air stream before they reach the electrostatic air cleaner.

12. A device for removing airborne particles from the air within a passenger compartment of a vehicle comprises electrostatic air cleaner unit located at a junction between an air intake for external air and an air intake for recycled air from the interior of the passenger compartment of the vehicle, means for mixing the two air streams and means for supplying the combined air mixture to the inlet of an electrostatic air cleaner, fan means located beyond the air cleaner to draw the air mixture through the air cleaner and to exhaust the cleaned mixed air into the interior of the passenger compartment.

13. A device as claimed in claim 12 in which the air is exhausted into the passenger compartment through a heater unit.

14. A device as claimed in claim 12 or 13 in which the air is into the passenger compartment through an air conditioning unit.

15. A device for removing airborne particles from the air within the passenger compartment of a vehicle constructed arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.

1 6. A vehicle including a passenger compartment and a device for removing airborne particles from air entering the compartment as claimed in any of the preceding claims.