GB2592708A

GB2592708A - Breathalyser

Info

Publication number: GB2592708A
Application number: GB2018712.6A
Authority: GB
Inventors: John Sullivan Alan
Original assignee: Breathablok Ltd
Current assignee: Breathablok Ltd
Priority date: 2020-11-27
Filing date: 2020-11-27
Publication date: 2021-09-08
Anticipated expiration: 2040-11-27
Also published as: GB202018712D0; GB2592708B

Abstract

A breathalyser 10 comprising: an alcohol sensor 14; a blow tube 16 with an inlet 16a for the user to exhale air therein; a splitter 18 in the blow tube 16 to divide the blow tube into a primary conduit 20 and a secondary conduit 22; wherein the primary conduit 20 directs a first air stream to the sensor 14; and the secondary conduit 22 has an aperture 24 to vent out a second exhaled air stream. The body 12 may define a chamber 30, with an outlet 32, to receive the first exhaled air stream and direct it to the sensor 14. The breathalyser 10 may also have a shield 26 and a protrusion 28, wherein they have a hydrophobic/waterproof coating to allow liquid droplets to run into a drain aperture (Fig. 4, 29). The breathalyser 10 may further have a tilt sensor and a valve that prevents air flow when the breathalyser is not in the desired orientation. The breathalyser detects blood alcohol content/concentration (BAC) with improved accuracy by reducing water droplets in the analysed air stream.

Description

BREATHALYSER

BACKGROUND

The present invention relates to a breathalyser. More specifically, the present invention relates to a blow tube for a breathalyser. Even more specifically, the present invention relates to a blow tube for a breathalyser that divides an exhaled air stream into: a first stream that is analysed by the breathalyser; and a second stream that is vented from the blow tube without being analysed by the breathalyser.

Various breathalysers with blow tubes or mouth pieces are known. Many known breathalysers also include non-circumvent features, such as a one-way valve to prevent a user inhaling instead of exhaling air via the blow tube.

Since breathalysers determine the concentration of alcohol vapour in gaseous breath, it is also known that: * breathalyser readings are affected by the temperature of the air; and * breathalysers (in particular sensors housed within the breathalyser) are sensitive to exposure to liquid and liquid droplets (as opposed to vapour).

A drawback of existing breathalysers is that they permit the entire exhaled air stream to be analysed by the breathalyser sensor, thereby including the portion of the air stream that has travelled over the moist tongue, which air stream portion is: cooled by the relatively cooler upper tongue surface; and is more prone to the inclusion of liquid droplets.

It is an object of the present invention to address this drawback.

SUMMARY OF THE INVENTION

According to a preferred embodiment of the invention, there is provided a breathalyser that includes: a sensor for sensing the concentration of alcohol in an exhaled air stream; and a blow tube defining an axial inlet through which an exhaled air stream is, in use, directed into the blow tube; characterised in that: a splitter is disposed within the blow tube, which splitter divides the blow tube into a primary conduit and a secondary conduit, in use, dividing the exhaled air stream directed into the blow tube into a first exhaled air stream directed through the primary conduit and a second exhaled air stream directed through the secondary conduit the radial wall of the blow tube defines an aperture along the secondary conduit, in use, to vent the second exhaled air stream from the blow tube; and the primary conduit is in fluid communication with the sensor, in use, directing the first exhaled air stream to the sensor.

Typically, the breathalyser further includes a body to which the blow tube is removably secured.

Generally, the body defines: a chamber that is in fluid communication with the primary conduit, in use, to receive the first exhaled air stream from the primary conduit; a chamber outlet that, in use, permits outflow of a portion of the first exhaled air stream from the chamber and a sensor inlet that, in use, permits flow of a portion of the first exhaled air stream from the chamber to the sensor.

Preferably: the area of the aperture defined by the radial wall of the blow tube is less than 40% of the axial cross-sectional area of the blow tube inlet; and the area of the chamber outlet is less than 40% of the axial cross-sectional area of the blow tube inlet; Typically, the aperture defined by the radial wall of the blow tube is sized, in use, substantially to equalise pressure within the primary and secondary conduits during flow of an exhaled air stream through the blow tube.

Generally, the splitter includes: a first portion that extends axially along the blow tube and is arcuate in axial cross-section; and a second portion that extends from the first portion of the splitter towards the aperture defined by the radial wall of the blow tube.

Preferably, the first portion of the splitter extends to the axis of the blow tube.

Typically, a shield extends from the first portion of the splitter radially, through the primary conduit and towards the radial wall of the blow tube, defining a radial gap between the radial outer edge of the shield and the radial inner wall of the blow tube.

Generally, the shield includes a hydrophobic coating that, in use, facilitates coalescing of liquid droplets thereon.

Preferably, the blow tube defines a protrusion that: extends from the radial inner wall of the blow tube: radially into the primary conduit; and beyond the radial outer edge of the shield; and is axially spaced from the shield in a direction away from the blow tube inlet.

Typically, the protrusion defined by the blow tube includes a hydrophobic coating that, in use, facilitates coalescing of liquid droplets thereon.

Generally: the primary conduit defines an outlet that, in use, discharges the first exhaled air stream from the primary conduit into the chamber defined by the body; and the shield extending from the splitter and the protrusion defined by the blow tube ensure that, in use, the flow of the first exhaled air stream is not linear along the length of the primary conduit.

Preferably, the splitter defines at least one drainage aperture that, in use permits liquid droplets running under the influence of gravity along the shield or the protrusion to flow via the drainage aperture defined by the splitter towards the aperture defined by the radial wall of the blow tube.

Typically, the breathalyser further includes a tilt sensor that only permits the sensor to take a reading when the breathalyser is in a desired orientation.

Generally, the breathalyser further includes a valve that, in use, prevents or restricts flow of the first exhaled air stream through the primary conduit or the chamber defined by the body when the tilt sensor senses that the breathalyser is not in the desired orientation.

Preferably, the breathalyser further includes: a first cover that extends over the aperture defined by the radial wall of the blow tube; and a second cover that extends over the chamber outlet.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawing in which: Figure 1 is a side view of a breathalyser according to a preferred embodiment of the invention; Figure 2 is a front view of the breathalyser in Figure 1; Figure 3 is a cross-sectional side view of the breathalyser through section A-A in Figure 2; Figure 4 is a cross-sectional perspective side view of a blow tube forming part of the breathalyser in Figure 1; Figure 5 is a perspective upper view of the blow tube in Figure 4; and Figure 6 is a perspective lower view of the blow tube in Figure 4.

DESCRIPTION OF THE INVENTION

With reference to Figures 1 to 6, a breathalyser 10 includes a body 12, a sensor 14 and a blow tube 16. Typically, the breathalyser 10 is associated with a vehicle or machinery (not shown), ensuring that only persons (not shown) that pass a breath alcohol concentration test performed by the breathalyser 10 may operate the vehicle or machinery.

The sensor 14 is of a type that measures the concentration of alcohol in an exhaled air stream.

The blow tube 16 is a right circular cylindrical tube that is removably secured to the body 12. The blow tube 16 is hollow with an open first axial end 16a and a partially open second axial end, in use, to permit the flow of an exhaled air steam therethrough. The first open axial end of the blow tube 16a presents the tube inlet.

A splitter 18 is disposed within the blow tube 16. The splitter 18 divides the blow tube 16 into a primary conduit 20 and a secondary conduit 22. In use, the splitter 18 divides the exhaled air stream directed into the blow tube (via the blow tube inlet 16a) into: a first exhaled air stream that is directed through the primary conduit 20; and a second exhaled air stream that is directed through the secondary conduit 22.

The radial wall of the blow tube 16 defines an aperture 24 along the secondary conduit 22. More specifically, the aperture 24 defined by the radial wall of the blow tube 16 is at or near an axial end of the secondary conduit 22 distal the blow tube inlet 16a. In use, the aperture 24 defined by the radial wall of the blow tube 16 vents the second exhaled air stream from the blow tube 16 / from the secondary conduit 22.

Of the primary and secondary conduits 20 and 22, only the primary conduit 20 is in fluid communication with the sensor 14, in use, directing the first exhaled air stream to the sensor 14.

The splitter 18 includes: a first portion 18a that extends axially along the blow tube A-A and is arcuate in axial cross-section (i.e. as shown in Figure 2); and a second portion 18b that extends from the first portion 18a of the splitter 18 towards the aperture 24 defined by the radial wall of the blow tube 16.

With particular reference to Figures 2 and 3, the first portion 18a of the splitter 18 extends from the radial inner wall of the blow tube 16 to the axis A-A of the blow tube 16. It will be appreciated that the shape of the first portion 18a of the splitter 18 is similar to the curved shape of the upper surface of a user's tongue. Accordingly, when a user exhales into the blow tube 16, the portion of the exhaled air stream that passes over the user's tongue is directed into the secondary conduit 22, while the residual exhaled air stream is directed into the primary conduit 20.

The splitter 18 further includes a shield 26 that extends from the first portion 18a of the splitter 18 radially, through the primary conduit 20 and towards the radial wall of the blow tube 16. Since the shield 26 stops short of the radial inner wall of the blow tube 16, a radial gap is defined between the radial outer edge of the shield 26 and the radial inner wall of the blow tube 16. In use, to facilitate coalescing of liquid droplets on the shield 26, a hydrophobic coating is applied to the shield 26. Alternatively, the shield 26 could be made of a hydrophobic material.

The radial inner wall of the blow tube 16 defines a protrusion 28 that: extends from the radial inner wall of the blow tube 16: radially into the primary conduit 20; and beyond the radial outer edge of the shield 26 (i.e. the protrusion 28 extends from the radial inner wall of the blow tube 16 a distance greater than the radial gap defined between the radial outer edge of the shield 26 and the radial inner wall of the blow tube 16); and is axially spaced from the shield 18 in a direction away from the blow tube inlet 16a.

In use, to facilitate coalescing of liquid droplets on the protrusion 28, a hydrophobic coating is applied to the protrusion 28. Alternatively, the protrusion 28 could be made of a hydrophobic material.

The shield 26 and protrusion 28 ensure that, in use, the flow of the first exhaled air stream is convoluted / tortuous / serpentine, i.e. non-linear, effectively forcing the first exhaled air stream to impact either (or both of) the shield 26 and the protrusion 28 as the first exhaled air stream flows along the primary conduit 20.

In use, the non-linear flow path provided by the primary conduit 20 coupled with the hydrophobic surfaces of the shield 26 and protrusion 28 facilitate coalescing of liquid droplets on the shield 26 and protrusion 28.

The splitter 18 further defines a pair of drainage apertures 29 that, in use permits liquid droplets running under the influence of gravity along the shield 26 or the protrusion 28 to flow via the drainage apertures 29 defined by the splitter 18 towards the aperture 24 defined by the radial wall of the blow tube 16, thereby removing liquid droplets from the first exhaled air stream and preventing them from passing through to the sensor 14.

The body 12 defines a chamber 30 that is in fluid communication with the primary conduit 20, in use, to receive the first exhaled air stream from the primary conduit 22 via a primary conduit 22 outlet 20a. The body 12 further defines a chamber outlet 32 that, in use, permits discharge of a portion of the first exhaled air stream from the chamber 30. Furthermore, the body 12 defines a sensor inlet 34 that, in use, permits flow of a portion of the first exhaled air stream from the chamber 30 to the sensor 14.

In use, the first exhaled air stream exiting the primary conduit 22 enters the chamber 30 and swirls around the chamber 30 before allowing: a portion of the first exhaled air stream to discharge from the chamber 30 via the chamber outlet 32; and a portion of the first exhaled air stream to pass from the chamber 30 into the sensor 14 via the sensor inlet 34.

In use, to maintain the requisite pressure within: * the secondary conduit 22, the area of the aperture 24 defined by the radial wall of the blow tube 16 is less than 40% of the axial cross-sectional area of the blow tube inlet 16a; and * both the chamber 30 defined by the body 12 and the primary conduit 20, the area of the chamber 30 outlet 32 is less than 40% of the axial cross-sectional area of the blow tube inlet 16a.

More specifically, the area of the aperture 24 defined by the radial wall of the blow tube 16 is sized and shaped, in use, substantially to equalise pressure within the primary and secondary conduits 20 and 22 during flow of an exhaled air stream through the blow tube 16. In this specification "substantially to equalise" is intended to mean that the difference between the pressure within the primary and secondary conduits 20 and 22 does not vary by more than 20%.

To prevent a user from inadvertently covering the aperture 24 defined by the radial wall of the blow tube 16 and/or the chamber 30 outlet 32 with his fingers: a first cover (not shouwn) could extend over the aperture 24 defined by the radial wall of the blow tube 16; and a second cover (not shown) could extend over the chamber 30 outlet 32.

The breathalyser 10 further includes a tilt sensor (not shown) in the form of an inclinometer that senses the orientation of the breathalyser 10. Preferably, the breathalyser 10 is operated when vertical, as the secondary conduit 22 would then, in use, receive the exhaled air stream portion that flowed over the user's tongue (as intended). The tilt sensor could be associated with the sensor 14 to permit the sensor 14 to take a reading only when the breathalyser is in this desired vertical orientation. Furthermore, the breathalyser 10 could include a valve (not shown) that, in use, prevents or restricts flow of the first exhaled air stream through the primary conduit 20 or the chamber 30 defined by the body 12 when the tilt sensor senses that the breathalyser 10 is not in the desired vertical orientation.

In use: * a user wishing to operate a vehicle or machinery with which the breathalyser 10 is associated would bring the blow tube 16 to his lips (with the breathalyser orientated vertically) and exhale therethrough.

* Due to the cooler temperature of the tongue's upper surface relative to the rest of the mouth and liquid pooled about the tongue, the exhaled air stream flowing over the tongue is cooler and includes more moisture / liquid droplets than the residual exhaled air stream.

* The splitter 18 separates the exhaled air stream that flowed over the tongue from the residual exhaled air stream, directing the exhaled air stream that flowed over the tongue into the secondary conduit 22 and the residual exhaled air stream into the primary conduit 20.

* The second exhaled air stream (i.e. the exhaled air stream that flowed over the tongue) is vented from the blow tube 16 via the aperture 24 defined by the radial wall of the blow tube 16. Accordingly, this second exhaled air stream does not come into contact with, and is not analysed by the sensor 14.

* The first exhaled air stream (i.e. residual exhaled air stream) flows along the nonlinear primary conduit, impacting the shield 26 and the protrusion 28, coalescing liquid droplets on their hydrophobic surfaces, which droplets are ultimately drained under the influence of gravity by the aperture 24 defined by the radial wall of the blow tube 16 (after flowing through the drainage apertures 29 defined by the splitter 18).

* The first exhaled air stream then passes via the primary conduit outlet 20a into the chamber 30 defined by the body 12, where the first exhaled air stream swirls before partly being discharged from the chamber 30 via the chamber 30 outlet 32 and partly flowing into the sensor 14 via the sensor inlet 34.

* The sensor 14 measures the alcohol concentration of the first exhaled air stream portion that flowed into the sensor 14, and permits operation of the machinery or vehicle only if the measured alcohol concentration of such first exhaled air stream portion is below a predetermined level.

Since the sensor 14 is sensitive to both temperature and liquid -operating better at higher temperature and with fewer liquid droplets in the exhaled air stream analysed -it will be appreciated that the blow tube 16 with separator 18 assists in efficient and accurate operation of the sensor 14/ breathalyser 10.

Claims

CLAIMS1. A breathalyser (10) including: a sensor (14) for sensing the concentration of alcohol in an exhaled air stream; and a blow tube (16) defining an axial inlet (16a) through which an exhaled air stream is, in use, directed into the blow tube; characterised in that: a splitter (18) is disposed within the blow tube, which splitter divides the blow tube into a primary conduit (20) and a secondary conduit (22), in use, dividing the exhaled air stream directed into the blow tube into a first exhaled air stream directed through the primary conduit and a second exhaled air stream directed through the secondary conduit; the radial wall of the blow tube defines an aperture (24) along the secondary conduit, in use, to vent the second exhaled air stream from the blow tube; and the primary conduit is in fluid communication with the sensor, in use, directing the first exhaled air stream to the sensor.
2. The breathalyser according to claim 1. further including a body (12) to which the blow tube is removably secured.The breathalyser according to claim 2, wherein the body defines: a chamber (30) that is in fluid communication with the primary conduit, in use, to receive the first exhaled air stream from the primary conduit; a chamber outlet (32) that, in use, permits outflow of a portion of the first exhaled air stream from the chamber; and a sensor inlet (34) that, in use, permits flow of a portion of the first exhaled air stream from the chamber to the sensor.The breathalyser according to claim 3, wherein: the area of the aperture defined by the radial wall of the blow tube is less than 40% of the axial cross-sectional area of the blow tube inlet; and the area of the chamber outlet is less than 40% of the axial cross-sectional area of the blow tube inlet; The breathalyser according to claim 4, wherein the aperture defined by the radial wall of the blow tube is sized, in use, substantially to equalise pressure within the primary and secondary conduits during flow of an exhaled air stream through the blow tube.6. The breathalyser according to claim 5, wherein the splitter includes: a first portion (18a) that extends axially along the blow tube and is arcuate in axial cross-section; and a second portion (18b) that extends from the first portion of the splitter towards the aperture defined by the radial wall of the blow tube.7. The breathalyser according to claim 6, wherein the first portion of the splitter extends to the axis (A-A) of the blow tube.The breathalyser according to claim 7, wherein a shield (26) extends from the first portion of the splitter radially, through the primary conduit and towards the radial wall of the blow tube, defining a radial gap between the radial outer edge of the shield and the radial inner wall of the blow tube.9. The breathalyser according to claim 8, wherein shield includes a hydrophobic coating that, in use, facilitates coalescing of liquid droplets thereon.10. The breathalyser according to claim 9, wherein the blow tube defines a protrusion (28) that: extends from the radial inner wall of the blow tube: radially into the primary conduit; and beyond the radial outer edge of the shield; and is axially spaced from the shield in a direction away from the blow tube inlet.11. The breathalyser according to claim 10, wherein the protrusion defined by the blow tube includes a hydrophobic coating that, in use, facilitates coalescing of liquid droplets thereon 12. The breathalyser according to claim 11, wherein: the primary conduit defines an outlet (20a) that, in use, discharges the first exhaled air stream from the primary conduit into the chamber defined by the body; and the shield extending from the splitter and the protrusion defined by the blow tube ensure that, in use, the flow of the first exhaled air stream is not linear along the length of the primary conduit.13 The breathalyser according to claim 12, wherein the splitter defines at least one drainage aperture (29) that, in use permits liquid droplets running under the influence of gravity along the shield or the protrusion to flow via the drainage aperture defined by the splitter towards the aperture defined by the radial wall of the blow tube.14. The breathalyser according to claim 13, further including a tilt sensor that only permits the sensor to take a reading when the breathalyser is in a desired orientation.The breathalyser according to claim 14, further including a valve that, in use, prevents or restricts flow of the first exhaled air stream through the primary conduit or the chamber defined by the body when the tilt sensor senses that the breathalyser is not in the desired orientation.16. The breathalyser according to claim 15, further including: a first cover that extends over the aperture defined by the radial wall of the blow tube; and a second cover that extends over the chamber outlet.