GB2140912A

GB2140912A - Humidity controlling device

Info

Publication number: GB2140912A
Application number: GB08312962A
Authority: GB
Inventors: John Frederick Colston James
Original assignee: COLSTON JAMES J F
Current assignee: COLSTON JAMES J F
Priority date: 1983-05-11
Filing date: 1983-05-11
Publication date: 1984-12-05
Also published as: GB8312962D0

Abstract

A humidity controlling device has a casing enclosing airflow chambers (21,22), one of which (21) contains drying means for removing water vapour from air passing therethrough, and the other of which contains water to supply water vapour to air passing therethrough. A sensor which senses atmospheric humidity is disposed at an inlet or an outlet of the device, and this sensor controls, by way of an electronic circuit, the flow of air to the chambers. A pivotally movable flap (23), is movable by a solenoid controlled by said circuit, the flap being able to prevent flow to a selected one of said chambers in response to said sensor. <IMAGE>

Description

SPECIFICATION Humidifier device This invention relates to a humidifier device.

As the cost of heating has increased sharply in recent years, it has become less common for heated rooms to be ventilated by the opening of a window, since this allows the escape of heat, which is thus wasted. However, without any ventilation a room heated, for example by central heating radiators, may well become uncomfortable through lack of moisture in the air. On the other hand too much moisture in the air in the room may be equally uncomfortable. There is thus a need for a humidifier device which is able to satisfy these varying requirements and which is effective and long lasting in use, and an object of the present invention is to provide such a device.

According to the present invention a humidifier device comprises means for drawing air, in use, through an inlet of the device, a first chamber having means therein for removing water vapor from air passing through said first chamber, a second chamber having means therein for supplying water vapour to air passing through said second chamber, at least one outlet for air leaving the device, and control means for controlling the flow of air, in use, through said chambers.

In this way the relative humidity of the air in the room can be controlled. The device can be set to a chosen relative humidity value and the device will then sense the relative humidity of the air flowing into or out of it and adjust its control means automatically so that the air flowing in the device receives more moisture or has moisture extracted from it, as required to produce the chosen relative humidity value.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure t is a perspective view of the humidifier device of the present invention; Figure 2 is a view of the humidifier device with part of the casing of the device removed; Figure 3 is a schematic representation of air flow within the device; Figure 4 shows, in detail, water vapour removal and supply means respectively of the device; Figure 5 shows an electrical sensing circuit of the humidifier device; and Figure 6 is a graph of the capacitance of a humidity sensor of the electrical circuit of Figure 5, against relative humidity; and Figure 7 is an on-off power control circuit incorporating the circuit of Figure 5.

Figure 1 shows that externally the humidifier device of the present invention has a rectangular casing supported on castors 10. In the embodiment shown in Figure 1 a shorter end wall 11 of the casing is provided with a grill 12 at the top thereof whilst a longer side wall 13 of the casing is likewise provided with a grill 14. As will be explained hereinafter air leaves the humidifier device through one or other of these grills. Figure 2 shows one possible arrangement of components within the interior of the casing of the device. Figure 2 shows how there is an opening 15 in the bottom of the casing, with a mechanical filter being disposed above it so as to clean air passing through said opening 15 into the interior of the humidifier device where it is to be processed.The filter 16 can advantageously filter particles down to 5 microns in size and is preferably of the throw-away replacement type, so that the filter can be changed at prescribed intervals to ensure that the air entering into the interior of the humidifier device is always relatively clean.

Above the filter 16, is a fan blower unit 17, which can be electronically speed controlled, this unit being disposed beneath a partition 18 in the casing, the partition separating the interior of the casing into upper and lower regions. The partition has an opening 19 therein through which air is blown by the fan blower unit 17, in use. Thereafter the air enters a space 20 from where it flows into either a drying chamber 21 or a wetting chamber 22. A pivoted flap 23 is arranged, in this example, so that it closes the entrance to one of the drying chamber and the wetting chamber, with the other of said chambers having its entrance open so that air passes into it. In Figure 2 the flap 23 is shown closing the entrance to the drying chamber 21 so that in such a position air would flow into the wetting chamber.With the pivoted flap 23 in the position shown in dashed lines in Figure 2, closing the entrance to the wetting chamber, air would thus flow to the drying chamber 21. Movement of the flap 23 is controlled by electronic and mechanical controls to be described hereinafter. To this end an electronic control box 24 can be positioned within the casing of the device as shown in Figure 2.

The wetting chamber 22 contains a water tank 25 with which is associated a wheel 26 which is mounted on the tank for rotation in a vertical plane with its lower portion dipping into the water in the tank 25 as the wheel 26 rotates. The wheel 26 is rotated by the flow of air passing through the humidifier device and this wheel 26 acts as a saturated rotary wick. The wheel 26 will be described in detail hereinafter with reference to Figure 4.

The drying chamber 22 contains a tank 27 in which is contained drying agent or desiccant. In a similar manner to the arrangement in the wetting chamber 22, a wheel 28 is mounted on the tank 27 so that its lower portion continuously passes through the drying agent as the wheel is rotated. However the wheel 21 is somewhat larger than the wheel 26. As mentioned this will be described in greater detail hereinafter with respect to Figure 4. Air leaving the chamber 21 flows out through the grill 12, while air from the chamber 22 flows out through the grill 14.

Whilst Figure 2 illustrates a specific, non-limiting example of the device of the present invention, Figure 3 schematically shows the device of the invention in general terms.

Figure 3 shows an inlet 29 of the device, in which is positioned an electronic sensor or probe 30, which, as will be explained, is part of the control circuit for operating the pivoted flap 23. As also shown in Figure 3 the sensor 30 may alternatively be posi tioned in an outlet 31 of the device instead of at the inlet. Air thus passes through said inlet 29 and through the mechanical filter 16 to the fan blower unit 17. It then passes to either the drying chamber 21 of the wetting chamber 22, this depending upon the position of the pivoted flap 23. As shown in Figure 3 the air passes along a passageway 32 which forms the wetting chamber, or alternatively a passageway 33 which forms the drying chamber. In these chambers respectively the tanks and wheels are arranged substantially as described with respect to Figure 2.The air then passes from the chamber to said outlet 31 where, as stated, said sensor 30 may be positioned instead of at the inlet 29.

As shown in Figure 3 the probe is connected to a Relative Hunidity electronic control unit 34, the details of which will be described with reference to Figure 5. This control unit controls operation of the flap 23, and in Figure 3 such operation is shown as being by way of a solenoid 35 which causes the flap to pivot to close one of the passageways 32 and 33 whilst leaving the other of said passageways open for passage of air. Any other suitable control means instead of a solenoid may be used, for example a motor operated louvre may be used instead of the solenoid controlled flap.

Figure 4 shows in detail the respective devices for adding moisture to air passing through the device or extracting air therefrom already described and shown with respect to Figures 2 and 3.

Figure 4 shows the wheel 26 pivotally mounted for rotation on the water tank 25. Around the periphery of the wheel 26 are a plurality of cups 36. The air passing through the wetting chamber drives said wheel 26 by way of said cups. The inner part of the wheel holds water in a wick or sock-like bag clipped to the sides of the wheel assembly. Thus one half of the wheel is submerged in the water of the tank 25 while the other half of the wheel is in the airstream flowing through the device. Evaporation thus takes place from the wick. The rotation of the wheel in the airstream is sufficient to overcome the viscosity of the water.

It is to be understood that this example shown in Figure 4 is in no way limiting in terms of the invention, since it will be appreciated that there are many various ways of transferring water to the airstream passing through the wetting chamber of the device. For example there could be provided a jet spray of water into the airstream or a wick suspended therein to feed water into the airstream. In addition the water provided in the wetting chamber could be provided with odourless disinfectant to kill any insects within the interior of the device so as to keep the water clean.

The drying device comprises, as already described, the tank 27 on which the wheel 28 is mounted for rotation. As with the wheel 26, the wheel 28 has cups 37 on its periphery so that it is rotated by way of the airstream in the drying chamber. The wheel 28 is filled with a drying or desiccating agent, for example silica gel. This is particularly suitable since it will absorb upto 40% of its weight in moisture. Likewise the tank in which the lower half of the wheel is submerged is also filled with silica gel. Where it is likely that extreme dampness may be found in the air to be passed through this chamber, an electric heater can be fitted inside the tank 27 if required.

The sensor or probe 30 is an atmospheric humidity sensor consisting of a non-conductive foil, which is covered on both sides with a iayer of gold. The dielectric constant of the foil changes as a function of the relative humidity of the ambient atmosphere and accordingly the capacitance value of the sensor is a measure of relative humidity. The foil is clamped between contact springs and assembled in a plastic housing. The characteristics of the sensor are not affected by an incidental condensation of water on the sensor foil. Figure 6 is a graph showing the relationship for the sensor between its capacitance and the relative humidity of the ambient air in which it is situated. It can be seen that the graph 38 is only slightly non-linear and for all practical purposes linearity may in fact be assumed.In operation in a room it is likely that the complete effective humidity range of the sensor of from 10 to 90% is unlikely to be required as humidities at the two extreme ends of this range are unlikely. It has been found that a particularly suitable sensor is one produced by Mullard. The capacitance of that sensor changes by about 0.4pF for each unit change in relative humidity.

Figure 5 shows an electronic sensing circuit of the control unit 34. The sensor 30 is shown as a variable capacitor which is connected with a resistor 39 and a pair of quadruple 2-input NOR gates 40 to form an oscillator. Two further NOR gates 41 are connected with a resistor42 and a number of capacitors 43 to 46 to form a second oscillator synchronous with the first oscillator. The capacitor 43 can be variable to provide a fine tuning and in this regard can be situated externally of the casing of the device so that a required relative humidity value can be set. The frequency of one of the oscillators is controlled by the sensor 30 whilst that of the oscillator is fixed.

Thus in effect a capacitance balancing circuit is provided. Each NOR gate is of the type HEF4001B integrated circuit. The oscillators produce pulse which can be made proportional to the portion of the capacitance of the sensor 30 which is dependent on the relative humidity.

Pulse substraction in a further circuit produces a pulsed output with a relative value proportional to relative humidity output. The output of the bridge circuit is connected to a further NOR gate 47 of the same type as the NOR gates 40 and 41. The output from the circuit is related to stabilized supply level. A supply voltage of, for example 8 volts is shown across a Zenor diode 48,whilstthe output voltage V0 is shown at 49. Compensation for the slight nonlinear output of the sensor 30 is carried out using a linearising circuit forming part of the circuit of Figure 5.

The electronic control circuit can be of on-off to 3 term control. Figure 7 shows an example of an on-off power control circuit incorporating the sensing or measuring circuit of Figure 5. The output voltage V0 of the measuring circuit is fed to a dual operational amplifier IC (NE532), the first operational amplifier 50 of the IC acting exclusively as an amplifier (with a gain for example of 2) and the second operational amplifier 51 acting as a voltage comparator.

The reference voltage (pin 6) of the comparator 51 can be adjusted between 600 mV and 3000 mV, giving a range in the present values of relative humidity between 20% and 100%. Atriac 52 (BT137D) controlled directly by the comparator, regulates power to for example a heater or fan. The use of negative d.c. control current allows the triac to operate in its most sensitive triggering quadrant.

D.C. triggering allows, moreover, the use of both inductive and resistive loads.

Instead of an on-off power control circuit, a time-proportional power control circuit, also incorporating the measuring circuit, could be used. This would give more accurate power regulation.

Instead of the air flowing wholly through the wetting chamber of the drying chamber, it would of course be possible to have a proportion of air flowing through one chamber with the remainder of the air flowing through the other chamber so as to control the humidity of the air being emitted from the device.

As stated the means of wetting and drying the air can be varied as required, for example the drying or wetting agent can merely be contained in a box, tray or separate stacked trays or boxes in the airstream. A person's particular requirement will obviously vary as to the relative humidity of the environment, but it is felt that 50% relative humidity will provide comfortable conditions. As explained the variable capacitor 43 will be controllable externally of the humidifier so that the required humidity level can be set by means of a scale.

Although the use of the cleaning filter 16 is desirable, it is not felt that this is essential, though its absence may eventually lead to contamination of the wetting and drying agents. Although the device would normally be mains operated, it is of course possible to make it portable with its own power supply.

After use of the device for some time it may be necessary to replenish the tank 25 with water and to renew the drying agent in the chamber 21.

Claims

1. A humidifier device comprising means for drawing air, in use, through an inlet of the device, a first chamber having means therein for removing water vapour from air passing through said first chamber, a second chamber having means therein for supplying water vapour to air passing through said second chamber, at least one outlet for air leaving the device, and control means for controlling the flow of air, in use, through said chambers.

2. A humidifier device as claimed in claim 1, wherein the flow of air is controlled by said control means so that, in use, it is either wholly through the first chamber or wholly through the second chamber.

3. A humidifier device as claimed in claim 1 or claim 2, in which the two chambers can be isolated from each other by means of a pivotally disposed flap which is movable between respective extreme positions in which it closes respective openings to said chambers.

4. A humidifier device as claimed in claim 3, in which movement of said flap is controlled by a probe which senses the humidity of air entering or leaving the device, in use.

5. A humidifier device as claimed in claim 4, in which said probe is part of an electronic control unit for controlling movement of said flap.

6. A humidifier device as claimed in claim 5, in which said electronic control unit controls operation of a solenoid which causes said flap to pivot.

7. A humidifier device as claimed in claim 5, in which said electronic control unit controls operation of a motor which causes pivotal movement of said flap in the form of a louvre.

8. A humidifier device as claimed in any one of claims 5 to 7, wherein said probe has a capacitance value which changes as a function of the relative humidity of the ambient atmosphere, and in said electronic control circuit forms part of a first oscilla torwhich with a second oscillator form a capacitance balancing circuit, the frequency of one of the oscillators being settable by a control to correspond to the humidity value required, and the frequency of the other oscillator being controlled by the probe.

9. A humidifier device as claimed in any one of the preceding claims, wherein in the first and second chambers are respective container means in which a drying agent and water respectively are contained.

10. A humidifier device as claimed in claim 9, wherein each container means is an upwardly open tank on which a wheel is pivotally mounted, the wheel having on its periphery a plurality of air receiving members so that the wheel is caused to rotate by means of airflowing through the chamber in which the wheel is disposed.

11. A humidifier device as claimed in claim 10, wherein the lower part of the wheel in the second chamber is submerged in the water in said tank and a wick is associated with the wheel to evaporate water into the air flowing in the second chamber.

12. A humidifier device as claimed in claim 10, wherein the lower part of the wheel in the first chamber is submerged in said drying agent.

13. A humidifier device as claimed in claim 12, wherein said wheel is filled with said drying agent.

14. A humidifier device as claimed in any one of claims 9 to 13, wherein said water contains disinfectant.

15. A humidifier device as claimed in any one of claims 9 to 14, wherein a heater is provided in said first chamber.

16. A humidifier device as claimed in any one of claims 1 to 8, wherein a jet spray of water is provided in said second chamber to supply water vapour to air flowing through said chamber.

17. A humidifier device as claimed in any one of the preceding claims, comprising an outer casing having an air inlet, and a fan blower unit to blow air from said inlet into the interior of the casing containing said first and second chambers.

18. A humidifier device as claimed in claim 17, wherein a filter is provided to clean air entering the device through said inlet.

19. A humidifier device as claimed in claim 17 or claim 18, wherein said casing has separate outlets from said first and second chambers respectively.

20. A humidifier device as claimed in any one of the preceding claims, and which has its own power supply associated therewith.

21. A humidifier device as claimed in any one of the preceding claims, and which is mains powered.

22. A humidifier device substantially as hereinbefore described with reference to and as shown in the accompanying drawings.