Air Quality Sensor Device

Abstract

An air quality sensor device 10 comprises a housing 12 having an air flow path defined by a first end portion 50 having an air inlet (18, fig 1), a first housing chamber (96, fig 12), a second housing

Description

The present invention relates to an air quality sensor device which is adapted for determining the composition of at least one component of air in a room, and preferably which is wirelessly communicable with other ventilation and filtration systems for the room. For ventilation and filtration systems in buildings, it is useful to know what the status of the air being treated is. Typically, the system owner will be interested in the gas composition, particularly in relation to carbon dioxide and pollutants, as well as an indication of the level of particulate matter in the air. An air quality sensor can be used to provide this information. However, there are various challenges associated with air quality monitoring. Firstly, where lots of different air quality characteristics are to be measured, an equivalent number of sensors is required. This can result in a bulky device, which is not aesthetically pleasing, and / or is cumbersome to move. Where bulky components are present, this can necessitate a large internal volume of the device, which can lead to recirculation of the air flowing through the device. This means that the sensors may be monitoring recirculated air, rather than fresh air from outside of the device. This can skew the measurements being made. Furthermore, the largely sealed nature of such air quality sensor devices is required to prevent damage or contamination of the sensor components. However, this can lead to clogging of the air inlet and outlet of the device with dust, since the user cannot readily clean the device. It is an object of the present invention to provide an air quality sensor device which overcomes or obviates the above-referenced problems. According to a first aspect of the invention there is provided an air quality sensor device comprising: a housing having a plurality of longitudinal sides, a first geometric end cap defining an air inlet of the air quality sensor, and a second geometric end cap at an opposite end of the housing which defines an air outlet of the air quality sensor; an electrically-energisable fan located in the housing for driving air between the air inlet and the air outlet; and a circuit substrate including at least one air quality sensor element, the circuit substrate comprising a plurality of circuit substrate portions which are hingeably interconnected, at least two of the plurality of circuit substrate portions including a wireless antenna, the circuit substrate being foldably receivable within the housing to at least in part adopt a cross-sectional geometric shape of the housing. To maximise the use of space within the air quality sensor, which has the additional advantage of minimising the space in which air eddies or recirculation can occur, the electrical components can be stacked in a space-efficient manner. One way in which this can be achieved is by matching the number of circuit substrate portions to the number of longitudinal sides, and then folding the circuit substrate into a corresponding number of portions. This shape matching of the shape of the whole device ensures that all free surfaces fold together to form a central air channel, encouraging air flow in a linear manner through the device. The construction of the circuit substrate is such that antenna can be positioned very easily so as to be angled relative to one another. In a preferred embodiment for communications, the circuit substrate portions would have antennae which are perpendicular to one another, for maximum signal coverage. The 60° angular arrangement of the circuit substrate portions of the triangular prism arrangement is also good for communication coverage. The air quality sensor device may be formed as a triangular prism. A triangular prism is the correct shape for a three-board device, which is a logical construction due to the need to provide a processor board, a sensor board, and a communications board. The device is also very stable, due to the low centre-o Optionally, each circuit substrate portion may be positioned at or adjacent to one of the plurality of longitudinal sides. The positioning of the circuit substrate portions is such that the air flow through the device is channelled in a mostly linear manner across the sensor elements. The air quality sensor device may further comprise a central support member which engages with the circuit substrate to hold the geometric shape. The risk with a foldable substrate is that the structure moves during use, and thus, a dedicated central support member which allows, and can indeed improve, air flow through the device is extremely useful. First and second end cap locators may be provided which are engagable with the central support member and which receive the respective first and second geometric end caps. End cap locators are used to hold the end caps in place, and for structural stability, these may connect directly to the central support member to buttress the geometry of the air quality sensor device. A plurality of said air quality sensors may be provided, the plurality of air quality sensors being provided on one circuit substrate portion. The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a front perspective representation of one embodiment of an air quality sensor device in accordance with the invention; Figure 2 shows a bottom perspective representation of the air quality sensor device of Figure 1; Figure 3 shows an exploded perspective representation of the air quality sensor device of Figure 1; Figure 4 shows a front perspective representation of a circuit substrate of the air quality sensor device of Figure 1; Figure 5 shows a front perspective representation of the circuit substrate of Figure 4 including a central support member installed, the circuit substrate being in a part-folded condition; Figure 6 shows a front perspective representation of the circuit substrate of Figure 5 in a fully folded condition; Figure 7 shows a bottom perspective representation of the circuit substrate of Figure 6; Figure 8 shows a front perspective representation of the circuit substrate of Figure 6, indicating the positions of end cap locators which interface with the central support member; Figure 9 shows a bottom perspective representation of an inner circuit assembly of the air quality sensor device of Figure 1; Figure 10 shows a bottom perspective representation of the inner circuit assembly of Figure 9 being inserted into an outer housing of the air quality sensor device; Figure 11 shows a front perspective representation of the air quality sensor device of Figure 1 with the end caps removed; Figure 12 shows a vertical cross-sectional representation through the air quality sensor device of Figure 1; Figure 13 shows a front perspective representation of the air quality sensor device of Figure 1, with the outer housing removed, the circuit substrate in part-folded condition, and the front half of the device shown in horizontal cross-section; Figure 14 shows the air quality sensor device of Figure 13, with the block arrows showing an air flow path through the device; Figure 15 shows the front perspective representation of the air quality sensor device of Figure 1 in horizontal cross-section; and Figure 16 shows the air quality sensor device of Figure 15, with the block arrows showing an air flow path through the device. Referring to Figure 1, there is indicated an air quality sensor device, referenced globally at 10, and which has an aesthetically appealing geometric profile. Here, the air quality sensor device 10 is provided in the form of a triangular prism, having a moulded outer housing 12 which presents a uniform outer surface of the device 10 along the longitudinal sides thereof. At either end of the outer housing 12 is provided an end cap 14 which has a shape which matches that of the geometry of the outer housing 12, here, being triangular end caps 14. The end caps 14 are slightly spaced apart from the outer housing 12 at a rim thereof, to form a gap 16, known as a shadow gap, through which air can enter and exit the air quality sensor device 10. Figure 1 shows the first end cap 14 which forms the air inlet 18 of the air sensor quality device 10, whereas Figure 2 shows the second end cap 14 which forms the corresponding air outlet 20. Air flow would, from an exterior of the air quality sensor device 10, appear to flow linearly through the centre of the device 10. The actual flow path through the air quality sensor device 10 is discussed in more detail below, however. Figure 2 shows the bottom of the air quality sensor device 10. The air quality sensor device 10 is intended to rest on one of the longitudinal sides of the outer housing 12, and this can be predefined by the manufacturer by the provision of one or more support elements, such as the feet 22 illustrated. These could be integrally moulded with the outer housing 12, or more preferably be provided as, for example, rubberised elements which provide additional grip for the air quality sensor device 10 when resting on another surface. A power inlet 24 is also provided, which may allow for a wired connection for the air quality sensor device 10. This air quality sensor device 10 is likely to be a comparatively heavy-duty air quality sensor device 10, and thus may not be a particularly portable unit. A wired connection is therefore preferred. Figure 3 highlights the underlying construction of the air quality sensor device 10. In the centre of the air quality sensor device 10, there is an inner casing 26 which is substantially the same shape as the outer housing 12, and which, in conjunction with a central support member 28, supports the circuit substrate 30 to which the electrical components of the air quality sensor device 10 are mounted. The main electrical component is an electrically-energisable fan 32 which serves to drive air through the air quality sensor device 10, and which is provided with a dedicated cover 34 to serve to direct airflow accordingly. The inner frame 26 is sealed using first and second end cap locators 36a, 36b which are respectively associated with the end caps 14 of the air inlet 18 and air outlet 20. The end cap locators 36a, 36b engage with the central support member 28, preferably via an interference fit, and sealingly close the inner frame 26 to form a housing chamber therein. Each end cap locator 36a, 36b comprises a receiver portion 38 into which a stem 40 of each end cap 14 is insertable. A rotatable locking connector 42 may be provided to ensure the connection between the end cap 14 and end cap locator 36a, 36b, which in the present embodiment, can be accessed through a central recess 44 of each end cap 14 and turned using a geometric key, such as a hex key or similar tool. A sealing element 46 is provided at an interface between each end cap 14 and the respective locator 36a, 36b in order to provide suitable control over the airflow therethrough. A dedicated filter 48 is provided upstream of the end cap locator 36a at the air inlet 16 in an attempt to limit large particulate ingress into the air quality sensor device 10. Each end cap 14 and associated end cap locator 36a, 36b can be considered to form an end portion 50 of the air quality sensor device 10. Figure 4 shows the circuit substrate 30 in detail. The circuit substrate 30 is here provided as hinged or foldable circuit substrate having a plurality of circuit substrate portions 30a, 30b, 30c which are pivotably engagable with one another. The circuit substrate 30 can thus be folded into the correct geometric configuration to be received into the air quality sensor device 10 so that each circuit substrate portion 30a, 30b, 30c extends along, or extends in parallel with, the longitudinal sides of the air quality sensor device 10. The first circuit substrate portion 30a comprises at least one, and preferably a plurality of sensor elements 52a, 52b. Here, there is a carbon dioxide sensor element 52a, and a plurality of complementary sensor packages 52b arranged in a grid on the rigid circuit board of the first circuit substrate portion 30a. The second circuit substrate portion 30b comprises additional electronic components, such as communications elements 54, which allows for wireless communication between the air quality sensor device 10 and other connected devices. Such connected devices could include air filtration or ventilation devices within a building or area which may be controlled via the air quality sensor device 10. The circuit board of the second circuit substrate portion 30b here includes a locator tab 56 which assists with connection to the central support member 28 once installed. Such a tab could be provided on any of the circuit substrate portions for this reason. The third circuit substrate portion 30c may comprise a further communications element 58. The geometric configuration of the folded circuit substrate 30 may thus improve the wireless connectivity of the air quality sensor device 10, since the longitudinal sides of the air quality sensor device 10 will be at 60° angles to one another, if an equilateral triangular prism geometry is chosen. This will ensure that there will be reasonable antenna pick-up regardless of the orientation of the air quality sensor device 10. The third circuit substrate portion 30c more importantly supports the electrically energisable fan 32, which could in fact be provided as the fan of a particulate sensor in order to improve the utility of the air quality sensor device 10. A moulded cover 34 for the electrically energisable fan 32 is dimensioned to control the air inflow and exhaust to and from the electrically energisable fan 32. An exhaust channel 60 is provided for directing air out of the fan 32, and an elongate inlet channel 62 is provided which connects to the air inlet 18 of the air quality sensor device 10 to ensure that there is no other air ingress to the main housing chamber other than via the electrically energisable fan 32. The elongate inlet channel 62 is not visible in Figure 4, but can be seen in Figure 13. An additional seal 64 may be provided to ensure this sealing is effective. The hinges of the circuit substrate 30 are preferably provided as circuit flexes 66 which permit electrical communication between the plurality of circuit substrate portions 30a, 30b, 30c. It will be appreciated that the circuit substrate could be formed as a flexible circuit substrate or similar flexible printed circuit board, or alternatively flexible wired connections could be provided between adjacent circuit substrate portions. The engagement of the central support member 28 with the circuit substrate 30 is shown in Figure 5. The central support member 28 is constructed as a central hub portion 68 from which extends three support arms 70a, 70b, 70c. The first support arm 70a engages with the locator tab 56 via an anchor portion 72a, whilst an end 72b of the second support arm 70b effectively hooks around the second circuit substrate portion 30b, and will hook onto the edge of the first circuit substrate portion 30a once it is raised. The first and third circuit substrate portions 30a, 30c can both be raised into place to clip into place with a retaining member 72c of the third support arm 70c. This assembled configuration is shown in Figures 6 and 7. The circuit substrate 30 and central support member 28, once assembled, form the core of an inner circuit assembly 74, as shown in Figure 8, in conjunction with the end cap locators 36a, 36b. The structure of the end cap locators 36a, 36b is shown in more detail in Figure 8. The first end cap locator 36a has an elongate opening 76 which acts as the passage from the gap 16 forming the air inlet 18 to the electrically-energisable fan 32. The elongate seal 64 is provided to connect the elongate opening 76 with the elongate inlet channel 62 of the cover 34 for the electrically energisable fan 32. There is also a port 78 in the first end cap locator 36a which connects with the exhaust channel 60 so that air expelled from the electrically-energisable fan can pass back through the first end cap locator 36a and into a baffle chamber formed between the first end cap locator 36a and the corresponding end cap 14. A corresponding seal 80 is then provided which couples between the exhaust channel 60 and the port 78. The second end cap locator 36b has a plurality of spaced apart exit vents 82 around the outer portion thereof, which allow venting from the inside of the inner circuit assembly 74 in a uniform or substantially uniform manner. Each end cap locator 36a, 36b includes a seal seat 84, which is formed as a triangular seat for a triangular seal 46, in a body thereof. This delineates between an outer portion 86 of the end cap locator 36a, 36b, which forms the air inlet 18 or air outlet 20 with the corresponding end cap 14, and an inner volume which is enclosed by the receiver portion 38 of the end cap locators 36a, 36b. The inner circuit assembly 74 is then completed by the addition of the inner casing 26, as per Figure 9, which preferably has first and second casing portions 26a, 26b to form a full side shell around the circuit substrate 30. The inner casing 26 may have one or more clips or connectors 88 which engage with the end cap locators 36a, 36b. As can be seen, the retaining member 72c may be configured to abut against the first casing portion 26a to provide additional structural rigidity. Figure 10 shows the inner circuit assembly 74 being inserted into the outer housing 12, so as to fit snugly inside the inner volume 90 of the outer housing 12. The power inlet 24 may be provided as a separate component, and fasteners 92 of the power inlet 24 may serve to lock the relative longitudinal positions of the inner circuit assembly 74 and the outer housing 12. To finally assemble the air quality sensor device 10, the end caps 14 are attached. This can be seen in Figure 11. The stems 40 are inserted into the receiver portions 38 of the first and second end cap locators 36a, 36b, and a rotatable locking connector 42 can lock into position in either the end cap locators 36a, 36b or central support member 28. An elongate hex key or screwdriver might be suited towards access through the central recess 44 of the end caps 14 to turn the rotatable locking connector 42. The filter element 48 may be provided which engages with the stem 40 of an end cap so as to be receivable in, in this instance, the receiver portion 38 of the first end cap 36a. The filter element 48 fills a large volume within the baffle chamber 94 formed between the end cap 14 and the first end cap locator 36a, and this can be seen in detail in Figure 12. Figure 12 illustrates how the air flow variation is achieved using the sealing at the first end cap locator 36a. Air enters the air inlet 18 all around the shadow gap 16, but cannot bypass the triangular seal 46. The only access into the air quality sensor device 10 for said air is through the elongate inlet channel 62 into the first chamber 96 in which the electrically energisable fan 32 is located. The triangular seal 46 by extension creates an inner volume which is sealed off from the outer portion of the end cap locator 36a. As noted above, this forms a baffle chamber 94 within which the filter element 48 is seated. The baffle chamber 94 acts as an intermediate air flow chamber between the first housing chamber 96 and the main, second housing chamber 98 which houses the circuit substrate 30. The engagement between the central support member 28 and the end cap locators 36a, 36b can be seen in more detail in Figure 12. The end cap locators 36a, 36b each have connector members 100 which engage with corresponding connectors 102 located in the hub portion 68 of the central support member 28. Internal substrate holders 104 of the inner casing 26 can also be seen in Figure 12, formed as hooked receivers which receivably engage the edges of the circuit substrate portions 30a, 30b, 30c. The air flow path leading to and from the baffle chamber 94 can be seen in more detail in Figures 13 and 15, and via the corresponding block arrows in Figures 14 and 16. Air enters through the gap 16 of the air inlet 18, and enters the elongate inlet channel 62, drawn through by the electrically energisable fan 32 in the first housing chamber 96. There is no direct air path into the second housing chamber 98. The exhaust channel 60 of the first housing chamber 96 connects to an inlet on the first end cap locator 36a, so that air exits the electrically-energisable fan 32 directly into the baffle chamber 94. The air is immediately filtered by the filter element 48, preventing large particulate matter from coming into contact with the downstream sensor elements 52a, 52b. The advantage of this construction is that, if the electrically energisable fan 32 is that of a particulate sensor, then the filtration occurs downstream of the particulate sensor, thereby enabling accurate reading of the particulate content, but upstream of the more sensitive sensor elements 52a, 52b. The outlets 106 of the baffle chamber 94 are provided on at least one, and preferably more than one, side wall 108 of the first end cap locator 36a which are spaced apart from the first housing chamber 96. The baffle chamber 94 thus serves as an airflow director which channels the air from the fan 32 backwards through the device 10, so that the air can pass in a near linear fashion through the second housing chamber 98. In essence, the baffle chamber 94 provides a turning motion to the air passing through. This effectively results in air exiting the baffle chamber 94 at one end of the second housing chamber 98 which is opposite to the air outlet 20 of the air quality sensor device 10. Air can thus flow from a first end portion of the air quality sensor device 10 to a second opposite end portion thereof. This creates linear air flow across the circuit substrate portions 30a, 30b adjacent to the outlets 106, avoiding the recirculation effects which can otherwise hamper air quality sensing equipment. Once linear flow is achieved, air can exit the air quality sensor device 10 through the exit vents 82 of the second end cap locator 36b, and out of the air outlet 20. It will be clear that, although a triangular prism shape has been chosen for, particularly but not necessarily exclusively, aesthetic purposes, other geometric configurations are feasible, such as cuboid, pentagonal prism, or hexagonal prism, byway of example only. It is therefore possible to provide a compact air quality sensor device having a geometry which not only facilitates the air flow through the device, and particularly across the sensors, but which has a novel circuit board configuration to minimise the volume of the device once assembled. The use of removable end caps at either end of the device also improves the ease with which a user can access and clean dust filters thereof. The words ‘comprises / comprising’ and the words ‘having / including’ when used herein with reference to the present invention are used to specify the presence of stated 5 features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, 10 described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein.

Claims

Claims 1. An air quality sensor device comprising: a housing having a first end portion having an air inlet, a first housing chamber, a second housing chamber, and a second end portion which is opposite the first end portion and having an air outlet; an electrically-energisable fan located in the first housing chamber which is configured to create an air flow path from the air inlet, through the first housing chamber, into the second housing chamber, and to the air outlet; an airflow director which directs air from the first housing chamber into the second housing chamber so as to enter the second housing chamber at or adjacent to the first end portion; and at least one air quality sensor element mounted in the second housing chamber on the air flow path; the air flow path extending through the second housing chamber from the first end portion to the second end portion. 2: An air quality sensor device as claimed in claim 1, wherein the at least one air quality sensor element is mounted at or adjacent to a longitudinal side of the housing.

3. An air quality sensor device as claimed in claim 2, wherein a plurality of said air quality sensor elements is provided.

4. An air quality sensor device as claimed in any one of the preceding claims, wherein the first end portion includes a baffle chamber positioned on the air flow path between the first and second housing chambers, the baffle chamber forming the airflow director.

3. An air quality sensor as claimed in claim 4, further comprising a filter element receivable in the baffle chamber upstream of the second housing chamber.

6. An air quality sensor device as claimed in any one of the preceding claims, wherein the first and second end portions each comprise an end cap locator and an end cap receivably engagable with the end cap locator.

7. An air quality sensor device as claimed in claim 6, wherein the air inlet and air outlet are respectively formed by a perimeter gap between the respective end cap locator and end cap of the first and second end portions.

8. An air quality sensor device as claimed in any one of the preceding claims, wherein electrically-energisable fan is provided as a particulate sensor fan.

9. An air quality sensor device comprising: a housing having first and second opposed end cap locators, a first end cap engaged with the first end cap locator which defines an air inlet of the air quality sensor, and a second end cap engaged with the second end cap locator which defines an air outlet of the air quality sensor device; an electrically-energisable fan located in the housing for driving air between the air inlet and the air outlet; and at least one air quality sensor element mounted in the housing; at least one of the first and second end caps being removably engagable with the first and second end cap locators respectively to permit dust extraction.

10. An air quality sensor device as claimed in claim 9, wherein the first and second end caps each comprise a stem receivably engagable with a corresponding receiver of the first and second end cap locators, respectively.

11. An air quality sensor device as claimed in claim 10, wherein the stem includes a recess via which a connector between the end cap and end cap locator is accessible.

12. An air quality sensor device as claimed in any one of claims 9 to 11, wherein the air inlet and air outlet are respectively formed by a perimeter gap between the respective end cap locator and end cap.

13. An air quality sensor device as claimed in any one of claims 9 to 12, wherein the first end cap locator and first end cap receivably engage with one another to form a baffle chamber within the air quality sensor device.

14. An air quality sensor device comprising: a housing having a plurality of longitudinal sides, a first geometric end cap defining an air inlet of the air quality sensor, and a second geometric end cap at an opposite end of the housing which defines an air outlet of the air quality sensor; an electrically-energisable fan located in the housing for driving air between the air inlet and the air outlet; and a circuit substrate including at least one air quality sensor element, the circuit substrate comprising a plurality of circuit substrate portions which are hingeably interconnected, the circuit substrate being foldably receivable within the housing to at least in part adopt a cross-sectional geometric shape of housing.

15. Anair quality sensor device as claimed in claim 14, wherein the air quality sensor device is formed as a triangular prism.

16. An air quality sensor as claimed in claim 14 or claim 15, wherein at least two of the plurality of circuit substrate portions include a wireless antenna.

17. An air quality sensor device as claimed in claim any one of claims 14 to 16, wherein each circuit substrate portion is positioned at or adjacent to one of the plurality of longitudinal sides.

18. Anair quality sensor device as claimed in claim any one of claims 14 to 17, further comprising a central support member which engages with the circuit substrate to hold the geometric shape.

19. An air quality sensor device as claimed in claim 18, further comprising first and second end cap locators engagable with the central support member and which receive the respective first and second geometric end caps.

20. Anair quality sensor device as claimed in any one of claims 14 to 19, wherein a plurality of said air quality sensors is provided, the plurality of air quality sensors being provided on one circuit substrate portion.

21. Anair quality sensor device comprising: a housing having a plurality of longitudinal sides, a first end cap defining an air inlet of the air quality sensor, and a second end cap at an opposite end of the housing which defines an air outlet of the air quality sensor; an electrically-energisable fan located in the housing between the air inlet and the air outlet; and at least one sensor element mounted in the housing.

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