PROTECTIVE HEADGEAR COMPRISING TEMPERATURE CONTROL APPARATUS
A protective headgear, such as a hard hat, is provided that comprises a protective outer shell, which surrounds the head of a wearer and in so doing defines a space between the head of the wearer and the underside of the outer shell; a heat-absorbing member; and a forced air ventilation apparatus. In use, the heat-absorbing member is positioned within the outer shell in the space formed between the head of the wearer and the outer shell, so that the forced air ventilation apparatus can provide a flow of ambient air from outside of the outer shell over the heat-absorbing pad within the space between the head of the wearer and the underside of the outer shell, thereby creating a cooling circulation of air around the head and face of the wearer. Suitably, the heat-absorbing pad comprises a phase-change material (PCM). The headgear may also comprise temperature sensors and systems for monitoring the temperature of the wearer remotely.
The present invention relates to ventilated personal protection systems, in particular protective headgear incorporating a cooling means.
BACKGROUNDPersonal protection systems in the form of hard hats are typically worn by those in environments or situations where they are at an increased risk of trauma to the head. Their main function is to protect the head of the wearer from injury due to flying or falling objects, impact with other objects and electric shock, and preventing force from being transmitted down the spine if an impact occurs from above.
Hard hats are required to have acceptable weight, a comfortable fit, and adequate ventilation, while meeting National and International standards for impact protection, such as the American National Standards ANSI/ISEA Z89.1-2009 Type 1, Class G and E. Presently there are two main types of protective hard hat in common usage in industry, such as the construction industry. The first is known as ANSI Type I or CSA Type 1 hard hats. Type I hard hats have a relatively simple design incorporating a hard outer shell and inner suspension attached to the inside of the shell. The outer shell is usually made from hard plastics such as high-density polyethylene (HDPE), acrylonitrile butadiene styrene (ABS) or other thermoplastic material and acts to resist and deflect blows to the head. The inner suspension holds the outer shell away from the head of the wearer. This allows the force from an external impact that would otherwise have been transmitted to the head to be reduced.
The other common type of hard hat is ANSI Type II or CSA Type 2. Type II hard hats are similar to Type I hard hats but comprise an additional foam liner, typically made of expanded polystyrene (EPS) that adds further protection against both vertical and lateral impacts. The foam liner typically resides between the outer shell of the hard hat and the inner suspension.
Hard hats are also commonly used in a range of industries including construction, heavy and light industrial, petrochemical, oil and gas, mining, road construction, forestry and the utility industries. Hard hats and helmets are also required in other activities where there exists an increased risk of head trauma. Examples include: motorcycling, riding sports such as horse riding, cycling; winter and extreme sports; and ball sports such as baseball, cricket and American football. Protective head gear is also commonly used in the military and in certain policing environments.
Users of hard hats typically suffer from the fact that they retain heat in hot climates. In desert or tropical climates it is not unusual for temperatures in working environments to exceed 40° C. on site. Such temperatures can also be reached in confined environments such as deep mines, or within poorly ventilated roofing spaces. Due to the restricted airflow under the hard hat when in use, heat from the covered head portion of the wearer can be trapped underneath. One of the key mechanisms for controlling thermal-regulation in the human body operates via evaporative and radiative heat transfer from the head to the surrounding environment. However, upon exposure to the sun, the outer shell of the hard hat can also absorb and trap thermal energy in close proximity to the head of the wearer and preventing normal thermal regulation and the loss of heat from the body of the wearer. In very hot climates, enclosed working conditions, or when the wearer is engaged in strenuous activity, the build-up of heat can be severe and potentially hazardous. This can lead to discomfort for the wearer, and at worse more severe consequences, such as heat stroke, a medical condition resulting from an elevation temperature of the brain. Heat stroke if not treated quickly may result in disorientation, disablement or even death. Even mild cases of heat stroke can lead to impairment of cognitive function which can be extremely dangerous in high risk work locations, such as on construction sites or at oil well drilling heads. Furthermore, discomfort caused by heat build-up in hard hats can lead to non-compliance with health and safety regulations on the wearing of hard hats with workers removing their protective headgear in areas of increased risk of harm from objects falling from above, impact with other objects and electric shock.
Previous attempts have been made to provide a means of cooling to hard hats. It is known, for example, that simply changing the colour of the outer shell of the hard hat from yellow or red to white reduces the absorbed thermal energy from the sun leading to lower internal temperature within the hat. Addition of a reflective material on the outer surface of the shell may increase the effect. However, this approach does not address the problem of body heat generated by the wearer. Ventilation holes in the outer shell also provide a means by which the heated air inside the hard hat may be released. Holes in the outer shell, however, can compromise the structural integrity of the shell, also leaving openings through which dust and debris may ingress.
Active cooling systems for helmets and hard hats have been proposed in the art. Various designs of hard hat that increase evaporative cooling through the incorporation of forced ventilation of the space between the outer shell and the wearer's head by means of a fan have been proposed see for example WO 2013/175932, US 2014/0143934, JP 2012/180606.
US 2004255364 describes a complex helmet cooling system that relies on thermoelectric cooling via the Peltier effect. Systems based on thermoelectric cooling suffer from using a brittle thermoelectric material, the need for a heat sink, a large demand for power resulting in the need for a heavy duty battery, being heavy, and the need for an umbilical cord between the helmet and the battery which presents a health and safety hazard. Incongruous systems also reduce user comfort and encourage removal of headgear.
The use of heat-absorbing materials in hats is also known. Full head cover cooling hats are used for cooling the heads of patients in hospitals. This may be to maintain the brain at a decreased temperature, for example to prevent swelling in infant's brains after ascendants or trauma at birth, or controlling overall body temperature.
Pads comprising heat-absorbing materials are also commercially available. These pads are placed directly into the inner suspension of typical Type I or Type II safety helmets. However, the thickness of the pad directly on top of the head of the user can result in instability of the helmet due to the shift in the centre of balance of the helmet. Direct contact of the head on the cooling pad may also lead to localised discomfort by causing formation of localised cold spots on the scalp of the wearer. The chilling effect of the pad is localised to below the pad resulting in poor distribution of the chilled air leading to over-chilling in certain regions, while others are not chilled sufficiently.
The present invention seeks to address the deficiencies of the prior art systems, most notably, the invention seeks to address the problem of overly bulky or incongruous cooling apparatus for protective headgear that encourages non-compliance of users due to discomfort.
SUMMARY OF THE INVENTIONThe present inventors have provided an integrated protective headgear cooling system, suitable for hard hats, helmets and the like, that effectively cools and ventilates the area between the shell of the headgear and the head of the wearer. The apparatus of the present invention demonstrates considerable advantage in that it is light and does not obstruct the free movement of the wearer, and most importantly, does not sacrifice the protection afforded by the shell to external forces, such as impact or electric shock.
Accordingly, a first aspect of the invention provides for a protective headgear comprising:
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- (i) an outer shell, which surrounds the head of a wearer and in so doing defines a space between the head of the wearer and the underside of the outer shell;
- (ii) a heat-absorbing member; and
- (iii) a forced air ventilation apparatus;
wherein the heat-absorbing member is positioned within the outer shell in the space formed between the head of the wearer and the outer shell, and wherein the forced air ventilation apparatus is arranged so as to provide a flow of ambient air from outside of the outer shell over the heat-absorbing pad within the space between the head of the wearer and the underside of the outer shell.
In an embodiment of the invention the flow of ambient air within the headgear is continuous.
In a specific embodiment of the invention, the heat-absorbing pad comprises a phase-change material (PCM). Suitably, the phase-change material comprises one or more of the group consisting of: an organic phase change material; an inorganic phase change material; and a eutectic phase change material. Optionally, the phase-change material comprises a salt hydrate; typically the salt hydrate is selected from: sodium sulfate decahydrate and sodium acetate hydrate.
In a specific embodiment of the invention the heat-absorbing pad comprises a contoured surface. Suitably, the contoured surface comprises at least one selected from the group consisting of: a groove; a channel; a baffle; an indentation; and an undulation.
In a specific embodiment of the invention the forced air ventilation comprises a fan. Typically, the forced air ventilation comprises one or more of the group consisting of: an axial-flow fan; a centrifugal fan; a mixed flow fan; and a cross-flow fan. In one embedment of the invention the fan is an axial-flow fan. Optionally, the fan is an electrical fan and is powered by a renewable energy source or by a power cell. In a particular embodiment of the invention, the renewable energy source comprises a solar energy array located on the outer shell. Suitably, the solar energy array comprises at least one photovoltaic cell.
In embodiments of the invention the outer shell comprises a material selected from the group consisting of: a polymer; carbon fibre; fibre-glass; fibre-metal; metal; and metal alloy. Suitably, the polymer comprises a hard thermosetting plastic or a hard thermoplastic; the hard thermoplastic may be selected from: a high-density polyethylene (HDPE); and an acrylonitrile butadiene styrene (ABS).
In a specific embodiment of the invention, the heat absorbing pad is reversibly attached to the underside of the outer shell. In a specific embodiment of the invention the headgear further comprises a suspension system to support the outer shell at a distance from the head of the wearer in order to provide the space there-between.
In an embodiment of the invention the head gear further comprises a suspension system to support the outer shell at a distance from the head of the wearer in order to provide the space there-between. Suitably, the heat absorbing pad is comprised within the suspension system.
According to one embodiment of the invention the forced air ventilation apparatus is positioned at the rear of the headgear, optionally at the base of the rear of the headgear. In yet a further embodiment of the invention the forced air ventilation apparatus is affixed to the outer shell.
In one embodiment of the invention the headgear is a hard hat that conforms to National and/or International standards for Impact Protection, suitably American National Standards ANSI/ISEA Z89.1-2009 Type 1, Class G and E.
Optionally, the headgear further comprises a temperature sensor. In an embodiment of the invention, the temperature sensor controls the actuation and/or speed of the forced air ventilation apparatus.
In a further embodiment of the invention, the headgear comprises a Global Positioning System (GPS) locating transponder, and optionally a wireless communications system. Suitably, the wireless communications system is configured so as to communicate local temperature information to a remotely located server.
A second aspect of the invention provides system for monitoring temperature status information of an individual, in which the temperature status information corresponds to the temperature within a protective headgear as described herein that is worn by the individual, wherein the system comprises:
a temperature sensor located within the headgear;
a wireless communications transmitter located within the headgear and in communication with the temperature sensor;
a wireless communications receiver located remotely;
and a central server that is in communication with the wireless communications receiver,
wherein, the temperature sensor generates temperature status information and communicates the information to the wireless communications transmitter, which in turn transmits the temperature status information to the remotely located wireless communications receiver, and thus to the central server.
The invention is illustrated by the following drawings in which:
All references cited herein are incorporated by reference in their entirety. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
As used herein, the term “comprising” means any of the recited elements are necessarily included and other elements may optionally be included as well. “Consisting essentially of” means any recited elements are necessarily included, elements that would materially affect the basic and novel characteristics of the listed elements are excluded, and other elements may optionally be included. “Consisting of” means that all elements other than those listed are excluded. Embodiments defined by each of these terms are within the scope of this invention.
The invention provides for cooled personal protection headgear systems, in particular a protective hard hat or helmet, incorporating apparatus and configured for cooling the head and the face of the user when in use.
As shown in
It will be understood that the term “forced air ventilation” as used herein refers to an active air ventilation system that directs circulation of air from the external environment to the space between the underside of the outer shell 12 and the wearer's head. A forced air ventilation system will typically comprise at least one air inlet, with venting provided by the gap around the outer circumference of the hat 10. Optionally, venting gaps or outlets can also be provided where appropriate to assist or direct the air circulation as appropriate.
The outer shell 12 is generally shaped to fit over the head and covers at least a portion of the head, typically at least a substantial portion of the frontal and parietal regions of the skull. Suitably the outer shell 12 covers at least the upper portion of the head above the eyes and ears. The outer shell 12 may extend down the sides of the head of the wearer and/or down the back of the head of the wearer largely in line with the contours of the head to cover at least the majority of the head excluding the face. The coverage should be sufficient to provide adequate protection of the head of the wearer from injury due to falling objects, impact with other objects and electric shock. Typically, such coverage should be compliant with national and international safety standards, for example for the construction, mining or oil and gas industries.
The outer shell 12 may be formed of any suitable material capable of withstanding or deflecting an impact. Typically, the outer shell 12 may be formed of a polymeric material, such as a hard plastic; a carbon fibre; a fibre-glass; a fibre-metal; or a metal. Where the outer shell is a hard plastic, this may be a hard thermosetting plastic or a hard thermoplastic. Suitably, hard thermoplastics may be chosen to be high-density polyethylene (HDPE) or acrylonitrile butadiene styrene (ABS). Fibre-metal relates to the class of materials consisting of a laminate of several thin metal layers bonded with layers of composite material. Where the outer shell is formed of metal, any suitable metal or metal alloy may be used. Typically, the metal for use in the outer shell 12 may comprise aluminum.
The outer shell 12 may comprise a brim 18 that extends outwardly from the centre at the base of the shell 12. The brim 18 may extend around the entire circumference of the outer shell 12, or it may just be present along a portion of the circumference. Suitably the brim 18 is located at the front of the outer shell 12 to provide sun shading to the eyes of the wearer. The brim 18 may offer additional protection from impact or shock, it may shoed the users eyes and face from weather conditions such as the sun and rain. The brim 18 may comprise a means for channeling water to a particular area of the outer shell, for example for channeling rain water to the front of the hat to prevent drainage onto the back and/or neck of the wearer in use.
The outer shell 12 may have appendages (not shown). These appendages may be fixed to or be an extension of the outer shell or the appendages may be removable. These appendages may extend downwardly in use from the lower edge of the outer shell 12 so as to cover the exposed skin on the face, head and neck of the wearer when in use. The appendages act to protect the wearer from adverse weather such as the sun, or rain.
The appendages may include drapes, skirts, visors or other shielding. Suitably the appendages comprise a flexible sheet material. The flexible sheet material may be made from natural or man-made synthetic fabrics. In embodiments of the invention where the appendage comprises a drape or skirt, suitable fabrics may be manufactured from cotton, nylon or polyester or a combination of these materials. Suitably the fabrics have a sun protection factor (SPF) of at least 2 according to EN ISO 24444:2010. Typically the fabric will have an SPF of at least 5, 10, 15, 30 or 50. The appendages may be water-resistant or repellent, or water-proof.
As shown in
The headband 20 may be contiguous, or it may be interrupted or partial. The headband may have a fixed circumference, or it may be adjustable. Adjustment of the circumference of the headband may be by any suitable means known in the art, for example, via a mechanical adjuster, plastic snap fitting, buckle, hook and loop tape, or elasticated means. In one embodiment, the headband 20 is contiguous with a mechanical adjuster.
The straps 22 may span the headband 20 in any direction. Suitably at least a first strap 22 spans the headband 20 in an approximately perpendicular direction to second strap 22 that spans the headband thereby preventing the headband slipping down the head of the wearer in use.
In certain embodiments of the invention, the straps 22 will generally follow the contours of the inner surface of the outer shell 12. In an embodiment of the invention there will be a gap, space or void 19 provided between the outer shell 12 and the straps 22.
In embodiments of the invention, the outer shell 12 may be fitted with a visor to protect the eyes (not shown), ear defenders for use in loud environments (not shown), or a chin strap to secure the hat 10 to the head of the wearer (not shown).
The heat-absorbing pad 14 may be of any shape and size suitable for positioning under the outer shell 12 of the hard hat 10 in use. In embodiments of the invention, the heat-absorbing pad 14 has the form of a planar slab where the thickness of the pad is less than its width. Typically the heat absorbing pad has a thickness of less than 10 cm. The heat-absorbing pad 14 may have a thickness of less than 8 cm, 7 cm, 6 cm, 5 cm, 4 cm, 3 cm, 2 cm, or 1 cm.
All shapes of the pad 14 are provided. Suitably the pad 14 may be generally circular, polygonal, square, oblong or rectangular. In some embodiments, the pad may take the shape and dimensions of the outer shell 12 under which it is positioned to maximise the surface area of the heat-absorbing pad 14 without it protruding from the shell 12. Such an arrangement would enhance the heat absorption of the pad 14, while minimising the risk of puncture. Alternatively, in other embodiments, the pad may protrude from the outer shell 12 to maximise heat absorption.
The heat-absorbing pad 14 may be positioned anywhere in the hat 10. Suitably the pad 14 is positioned towards the top of the hat 10, within the apex of the outer shell 12, in use so that the air cooled by the pad 14 may fall in the direction of the wearer when in use. In an embodiment of the invention that comprises an inner suspension 18, the heat-absorbing pad may be positioned in the gap or void 19 between the outer shell 12 and the straps 22 of the inner suspension 18. In an alternative embodiment of the invention, the heat-absorbing pad may be fixed to the outer shell 12 directly. Fixing of the pad to the outer shell 12 may be by any means. Suitably the means of fixing is non-permanent (e.g. a reversible fixing) such that the pad 14 may be easily removed from the hat 10. In embodiments of the invention, reversible fixing is by way of adhesive, hook and loop tape, press studs or straps.
In an embodiment of the invention, the heat-absorbing pad 14 may be formed into a solid planar block, or it may be formed with surface modifications that serve to increase the surface area of the pad, and/or to direct air circulation around the pad 14 when it is installed within the outer shell 12. Such modifications may comprise one or more grooves, channels, undulations, baffles and/or indentations. These modifications may serve to increase or decrease the velocity of circulating air within the void 19 between the outer shell 12 and the straps 22 of the inner suspension 18 and, thereby, alter the cooling characteristics of the hat 10.
The heat-absorbing pad 14 may be formed of any material that can absorb heat energy. In an embodiment of the invention, the pad 14 may be formed of heat conductive materials such as metal, with or without the use of a heat-sink arrangement, or the pad may be formed of materials with a high thermal capacity such as a ceramic, stone or concrete that may be chilled prior to use. Typically, the material of the heat-absorbing pad may be a phase-change material.
A phase change material (PCM) is generally a substance with a high latent heat capacity. Latent heat is the energy required to convert a solid into a liquid, or a liquid into a vapour without a change in its temperature. PCMs latent heat storage can be achieved through solid-solid, solid-liquid, solid-gas and liquid-gas phase changes. Water is an example of a phase change material. The known method of evaporative cooling works on the principle of cooling air by passing it over a wet surface where it is cooled through the absorption of the heat energy in the air by the water thereby providing the required latent heat of vaporisation to evaporate the liquid water to gaseous water vapour. Hence, in one embodiment of the invention the heat-absorbing pad 14 may comprise a water impregnated material, such as a dampened sponge, fabric pad, wicking material or an equivalent matrix. More typically, commercial heat-absorbing materials for PCMs rely on the solid-liquid phase change. Commercial PCMs may be formed of a wide-range of materials, classified into three main groups: organic PCMs are based on organic materials, i.e. comprised primarily of carbon and hydrogen, such as paraffin, sugar alcohols or fatty acids; inorganic PCMs are based on inorganic salt hydrates, such as sodium acetate hydrate or sodium sulfate decahydrate; and eutectic PCMs, generally based on salt-water solutions.
All forms of PCM are suitable for use in the heat absorbing pad 14 of embodiments of the invention herein described. Suitably, the PCM for the invention herein described uses a PCM that relies on the solid-liquid phase change. Typically the PCM may be selected from commercially available PCMs, such as those listed in Table 1 below.
The use of a PCM as the material from which the heat-absorbing pad 14 is formed has a number of advantages. Firstly, PCMs have a high capacity for heat absorption. In addition, the heat absorption capacity of the PCM is regenerative, for example by cooling the material via refrigeration; therefore the material may be used repeatedly without loss of function. Furthermore, as pads comprising PCMs generally are not chilled below their freezing point, therefore there is minimal risk of injury (through frost bite) or discomfort from over-cooling a heat absorbing pad 14 comprising a PCM.
The PCM may be chosen to have a phase change temperature suitable for the environmental conditions and body temperature of the user. Examples of suitable PCM comprising pads may include, for example, salt hydrate based PCMs including the commercially available Climsel™ C28 (Climator Sweden AB, Skövde, Sweden). The high heat storage capacity in the phase change from solid to liquid and the advantageous phase change temperature of 32° C. makes this material particularly appropriate to be used in this application. The PCM may also be chosen to be non-toxic in case of the risk of leakage of the material from the pad 14.
The forced air ventilation apparatus 17 may be positioned anywhere on the hard hat 10 provided the airflow is directed under the outer shell 12 and across the heat-absorbing pad 14. Suitably the at least one aperture 16 is positioned within the outer shell 12, although in embodiments of the invention a plurality of apertures may be present. Typically the forced air ventilation apparatus 17 is integral with the outer shell 12 and in close proximity to the aperture 16. Suitably, the forced air ventilation apparatus 17 may be positioned on the hat 10 above the face of the wearer when in use, or alternatively, it may suitably be positioned on the opposite side of the hat 10 above the nape of the neck of the wearer when in use. In embodiments of the invention, the forced air ventilation apparatus 17 may be positioned on the hat 10 at the base of the outer shell 12 directing a flow of ambient air upwardly into the void 19, past the heat-absorbing pad 14. Suitably, the heat-absorbing pad 14 will be positioned in the void 19 such that the airflow is directed into contact with the heat-absorbing pad 14. Airflow past the heat-absorbing pad 14 may be in any form. In embodiments of the invention, airflow may be directed above, below and/or to the side of the heat-absorbing pad 14, suitably, the airflow is directed above and below the heat absorbing pad 14.
In embodiments of the invention, where the aperture 16, and optionally the forced air apparatus 17, is positioned on the rear of the hat 10, diametrically opposed to the face of the wearer when in use, airflow of ambient temperature is directed into the void 19 under the outer shell 12, past the heat-absorbing pad 14, with the then cooled air venting the hat 10 above the face of the wearer in a downward direction. In this way, the wearer is exposed to a constant stream of cooled air passing over the face thereby facilitating effective radiative and evaporative cooling of the wearer's head and upper body.
Alternatively, in embodiments of the invention when the forced air ventilation 17 is positioned on the front of the hat 10, above the face of the wearer when in use and with or without an aperture 16, airflow is directed under the outer shell 12 into the void 19, across the surface of the heat-absorbing pad 14, with the cooled air then exiting the outer shell 12 of the hat 10 above the neck of the wearer in a downward direction. In this way, the wearer is exposed to a constant stream of cooled air passing over the neck.
According to the present invention, the combination of the forced air ventilation and the heat-absorbing pad 14 in a hard hat 10 provides a number of advantages.
Firstly, the cooling effect of the heat-absorbing pad 14 is no longer localised to one specific head area of the wearer within the outer shell 12 of the hat. In addition, the effect of ventilation and air cooling may be extended to also cover the face, neck and upper body.
In addition, the airflow past the heat-absorbing pad 14 acts to distribute the cooled air throughout the interior of the outer shell 11, thereby preventing uncomfortable over-cooling of the part of the head closest to the heat-absorbing pad, and insufficient cooling in parts of the hat 10 more distant from the heat-absorbing pad 14. Furthermore, airflow through the void 19 between the head of the wearer and the outer shell 12 prevents local heating of the air trapped in this region due to the direct heating effects of the sun on the outer shell 12 or from radiative and evaporative thermal transfer from wearer's body. Such heating may otherwise lead to premature exhaustion of the cooling effect of the pad 14.
The forced air ventilation apparatus 17 may comprise any type of mechanical or forced ventilation device, or mixed mode or hybrid ventilation that uses both mechanical and natural ventilation that is suitable for generating air circulation. In an embodiment of the invention, the forced air ventilation apparatus 17 comprises an electric fan assembly. The electric fan assembly may be of axial-flow, centrifugal, mixed flow or cross-flow design. In an embodiment of the invention, the fan is an axial-flow electric fan.
The forced air ventilation apparatus 17 may be powered by any suitable means. In embodiments of the invention, the forced air ventilation apparatus 17 may be powered by renewable energy sources, such as solar energy; or by other electrical power sources such as non-rechargeable or rechargeable power cells (e.g. batteries); or by mains electricity.
Suitable sources of renewable energy in the context herein are those that can provide sufficient electrical power to the forced air ventilation apparatus 17 so that it may provide a sufficient airflow to achieve the benefits of the invention. Suitably the collection means may be sized to be self-contained on the hat 10. In embodiments of the invention wherein the forced air ventilation apparatus 17 is powered by solar energy, a solar generating array or panel (e.g. a photovoltaic solar cell) may be advantageously positioned on the outer surface of the of the outer shell 12 to maximise its exposure to the sun, however, the positioning of the solar panel may be at any suitable position on the hard hat 10 to provide sufficient power output to supply the forced air ventilation apparatus 17.
In embodiments of the invention where batteries are used, the batteries may be non-rechargeable, for example, alkaline batteries, mercury batteries, silver-oxide batteries and zinc-carbon batteries. Alternatively, the batteries may be rechargeable, for example, nickel-cadmium batteries, nickel metal hydride batteries, lithium ion or lithium polymer batteries, or lead acid batteries.
In embodiments where the fan is powered by renewable energy sources, batteries may also be employed to temporarily store the power generated from the renewable source. This is particularly advantageous when the sun is obscured by cloud, when the user is not located in direct sunlight or at dusk or night time. The stored power may then be used to power the forced air ventilation apparatus 17 when the power generated from the renewable source is insufficient to maintain a satisfactory airflow. The battery employed for storing the energy from the renewable source may be rechargeable and, for example, selected from nickel-cadmium batteries, nickel metal hydride batteries, lithium ion or lithium polymer batteries, or lead acid batteries.
In embodiments of the invention requiring a local power source, such as batteries, these may be positioned at any suitable position on the hat 10, or elsewhere on the wearer within a power pack that may be linked to the hat 10 via an electrical connection such as a wire. The choice of positioning of the power pack depends on the balance of benefits of reducing weight of the hat by placing the power pack on the body of the wearer, compared to the freedom of movement obtained by having the power source positioned on the hat 10 thereby eliminating the need for a wired connection out from the hat 10 that may be subject to snagging or otherwise impair the movement of the wearer. Suitably the local power source is positioned on the hat 10, typically approximately diametrically opposed to the forced air ventilation apparatus 17 to balance the weight distribution of the hat as much as possible.
The airflow of the forced air ventilation apparatus 17 is controlled to a value typically less than 1 m3/min. In embodiments of the invention, the airflow of the fan may be less than 0.9 m3/min, 0.8 m3/min, 0.7 m3/min, 0.6 m3/min, 0.5 m3/min, 0.4 m3/min, 0.3 m3/min, or 0.2 m3/min. Suitably, the airflow is more than 0.01 m3/min. typically the airflow is more than 0.05 m3/min or 0.1 m3/min. Suitably, the airflow is more than 0.01 m3/min. The data shown in the non-limiting examples provided herein are for an average volume flow rate of typically 0.35 m3/min.
As shown, ambient air enters the void 19 between the outer shell 12 and the wearer's hat under the influence of the forced air ventilation apparatus 17. The air then passes across the heat-absorbing pad 14 before exiting at the front of the outer shell 12 and flowing over the face of the user. Due to the symmetry of the design, a forced air ventilation apparatus 17 positioned at the front of the hat 10 would be expected to provide a similar airflow with cooled air exiting the outer shell 12 at the rear and continuing to flow down over the neck of the wearer.
In embodiments of the invention where the heat-absorbing pad is grooved, contoured or has undulations, they may be formed, or oriented so that they provide channels or passageways for the air to pass the heat-absorbing pad in the direction from the forced air ventilation to the exit vent of the helmet. The grooves or undulations formed in the heat-absorbing pad may be used to direct airflow in a direction that is beneficial to distribution of the cooled air around the interior of the hat 10—e.g. to a particular vent location. Alternatively, grooves or undulations may be used to create turbulent airflow in order to disrupt convection currents within the void 19 and enhance the cooling effect.
In an embodiment of the invention, the hat 10 may further comprise a sensor to monitor the either the void 19 temperature and/or the skin surface temperature of the wearer. The sensor may be of any form suitable for measuring thermal energy. Suitably the temperature sensor may comprise: an infra-red temperature sensor, or a thermocouple.
In an embodiment of the invention, the temperature sensor communicates discrete temperature information of the wearer to a central server via wireless or mobile telecommunications system. The central server may be located within the site management facility, for example on a construction site, thereby alerting site management to the existence of potentially dangerous working conditions. In an alternative embodiment of the invention the sensor may comprise a close range wireless communication transponder (such as an NFC or Bluetooth® device) allowing the transmission of temperature information to the wearer themselves. In one embodiment, the wearer can be alerted to potentially harmful temperature conditions via wireless communication with an application (an ‘app’) held on their mobile telecommunications device. Hence, if the skin or void 19 temperature increases above a given threshold it may indicate that that the heat-absorbing pad 14 in the hat 10 is no longer providing sufficient cooling of the wearer and the pad 14 needs to be replaced or recharged. Alternatively, it may indicate that the environment that the wearer is exposed to is beyond the safe operating parameters for the cooling effect of the hat 10 to maintain the wearer's temperature at a safe working level. Monitoring of the wearer's temperature in this way is therefore an effective way of monitoring safe working conditions for the wearer, and may provide an effective logging method as evidence of safe working and compliance with local labour regulatory laws.
The temperature sensor may be used for thermostatic control of the forced air ventilation apparatus 17. In environments where the need for cooling may be variable, such as when the wearer is moving from inside to outside, or from a hot environment to a less hot environment, or is engaged in work that is more or less strenuous, it may be desirable to vary the speed of the airflow generated by the forced air ventilation apparatus 17 to match the present need. In embodiments of the invention, the speed control of the forced air ventilation apparatus 17 may be achieved by any suitable means such as by manual control by the operation of a speed controller by the wearer, or it may be automatic, using the temperature sensor in a feedback arrangement operating the forced air ventilation apparatus 17 only once a certain temperature threshold is exceeded. In embodiments of the invention, the speed of the forced air ventilation apparatus 17 may increase with the reported temperature through a range until the maximum speed of the forced air ventilation apparatus 17 is reached.
In an embodiment of the invention, the hat 10 may further comprise a GPS tracking device, or other means for monitoring the geographical position of a worker. The linking of temperature information with geographical location and time data may offer a means of identifying particularly difficult working areas to which workers have been exposed. It may also provide an effective means of logging exposure to conditions across working zones at a local or even global level. Hence, the invention provides a system for monitoring an important aspect of safe working conditions for workers across the world.
GPS tracking functionality within the hat 10 may also provide effective identification, via geo-tagging, of the location of the wearer in the event of an accident or other emergency.
The invention is further exemplified in the following non-limiting examples.
EXAMPLES Example 1 Effect on TemperatureAn embodiment of the hard hat 10 according to the present invention was subjected to a simulated environment typically found in a hot climate of increased ambient air temperature and/or direct irradiated heat.
The test used a hard hat 10 according to the invention comprising an outer shell 18, a heat-absorbing pad 14, inner suspension 18, and forced air ventilation apparatus 17 mounted at the front of the hat 10, powered by batteries in a battery pack 23 mounted at the rear of the hat 10. Comparative example hard hats that do not comprise a heat-absorbing pad 14 and/or forced air ventilation apparatus 17 were simulated by removing the heat-absorbing pad 14 from the hat 10 according to the invention and/or deactivating the forced air ventilation.
As shown in
Direct radiant heat from the sun was simulated by a 60 W tungsten light bulb 34 placed at the top of the enclosure 26 above the hat under test. This bulb 34 and the forced air ventilation apparatus 17 were separately controlled by a switching unit 36 positioned outside of the enclosure.
Heat from the wearers head was simulated by the radiant heat from a 40 W tungsten light bulb 38 mounted inside the dummy head 24. To mimic a constant temperature of the head of the wearer unaffected by the ambient temperature increase, or radiant heat in the test enclosure 24, the bulb 38 and an identical bulb 40 were controlled simultaneously via control unit 42 attached to a thermocouple thermometer located inside an identical hat 44 in a separate enclosure 46 held at ambient temperature. The hat 44 was also placed on a dummy head 46 within which the bulb 40 was mounted.
All temperature measurements were taken from a thermocouple thermometer 48 mounted in the hard hat under test once a steady-state temperature reading had been reached.
The thermal experiment results of the test are provided in Table 2 below:
The results clearly show that without any form of cooling, the temperature within a hard hat increases under simulated hot climate conditions of increased ambient temperature and direct radiated heat from the sun (Experiment 2, +14° C. increase).
The increase was lessened through the use of the fan alone (Experiment 3, +6° C. increase). The use of the PCM pad alone also provided a decrease (Experiment 6, −6° C. reduction).
The results clearly show, however, that the combination of the presence of a heat absorbing PCM pad and a forced ventilation means in the form of a fan mounted on the front of the hard hat provides superior cooling of the hard hat. Experiment 7 demonstrated a measured temperature decrease of 14° C. in the hat compared to the surrounding air temperature within the sealed enclosure 24.
Example 2 Temperature and Air Velocity Contour ModelingAccording to the model, ambient air enters the void 19 between the outer shell 12 and the wearer's hat under the influence of the forced air ventilation 16. The air then passes either side (top and bottom as shown) of the heat-absorbing pad 14 before exiting at the front of the outer shell 12 and flowing downwards over the plane of the face of the user. Due to the symmetry of the design, a forced air ventilation 16 positioned at the front of the hat 10 would be expected to provide a similar airflow with cooled air exiting the outer shell 12 at the rear and continuing to flow down over the neck of the wearer.
The pre-processor GAMBIT was used in meshing the simulated model into more than 4,000,000 tetrahedral cells. Using growth rate function option, meshes could be dense and smaller near air supply slots and human bodies; and growing when further away. This number of cells used with the growth function technique is considered sufficient, as the inventors performed grid independency check. Commercially available simulation software “Fluent 6.3” was incorporated to solve conservation of mass, momentum and energy in the processing of air distribution, and to analyze turbulence affection combined heat transfer on air distribution. In this work, the so-called standard k-ε turbulence model, one of the most widespread turbulence models for industrial applications, was utilized. Basic parameters included air temperature, air velocity, relative humidity and turbulence parameters were used for numerical prediction of indoor air distribution.
The various boundary conditions assumed for all the studied cases herein described later.
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- Human Body was set as wall with constant surface temperature of 32° C. which is the skin temperature at this activity level.
- PCM was set as wall with constant temperature of 28° C. which is the melting temperature of the chosen material.
- Helmet inner surface, was set as wall with heat flux of 50 W/m2 which is equivalent to the transferred heat due to incident solar intensity on the outer side.
- Electric fan with static pressure of 30 Pa.
- Ambient Temperature of 37° C.
The lighter areas on both
Furthermore, it can be clearly seen on the left hand side of
It is therefore demonstrated that the combination of a PCM pad and a forced ventilation in the form of a fan mounted directing airflow across the pad not only provides more uniform distribution of the air cooled by the pad within the area under the outer shell 12, but also provides a pleasant stream of cooled air to the face or back of the head/neck of the wearer in use, avoiding uncomfortable cold spots.
The aforementioned embodiments are not intended to be limiting with respect to the scope of the appended claims, which follow. It is contemplated by the inventors that various substitutions, alterations, and modifications may be made to the invention without departing from the spirit and scope of the invention as defined by the claims.
Claims
1. A protective headgear comprising:
- (i) an outer shell, which surrounds the head of a wearer and in so doing defines a space between the head of the wearer and the underside of the outer shell;
- (ii) a heat-absorbing member; and
- (iii) a forced air ventilation apparatus;
- wherein the heat-absorbing member is positioned within the outer shell in the space formed between the head of the wearer and the outer shell, and wherein the forced air ventilation apparatus is arranged so as to provide a flow of ambient air from outside of the outer shell over the heat-absorbing pad within the space between the head of the wearer and the underside of the outer shell.
2. The protective headgear of claim 1, wherein the flow of ambient air is continuous.
3. The protective headgear of claim 1, wherein the heat-absorbing pad comprises a phase-change material (PCM).
4. The protective headgear of claim 3, wherein the phase-change material comprises one or more of the group consisting of: an organic phase change material; an inorganic phase change material; and a eutectic phase change material.
5. The protective headgear of claim 4, wherein the phase-change material comprises a salt hydrate.
6. The protective headgear of claim 5, wherein the salt hydrate is selected from: sodium sulfate decahydrate and sodium acetate hydrate.
7. The protective headgear of claim 1, wherein the heat-absorbing pad comprises a contoured surface.
8. The protective headgear of claim 7, wherein the contoured surface comprises at least one selected from the group consisting of: a groove; a channel; a baffle; an indentation; and an undulation.
9. The protective headgear of claim 1, wherein the forced air ventilation comprises a fan.
10. The protective headgear of claim 9, wherein the forced air ventilation comprises one or more of the group consisting of: an axial-flow fan; a centrifugal fan; a mixed flow fan; and a cross-flow fan.
11. The protective headgear of claim 7, wherein the fan is an axial-flow fan.
12. The protective headgear of claim 9, wherein the fan is an electrical fan and is powered by a renewable energy source or by a power cell.
13. The protective headgear of claim 12, wherein the renewable energy source comprises a solar energy array located on the outer shell.
14. The protective headgear of claim 13, wherein the solar energy array comprises at least one photovoltaic cell.
15. The protective headgear of claim 1, wherein the outer shell comprises a material selected from the group consisting of: a polymer; carbon fibre; fibre-glass; fibre-metal; metal; and metal alloy.
16. The protective headgear of claim 15, wherein when the material is a polymer, the polymer comprises a hard thermosetting plastic or a hard thermoplastic.
17. The protective headgear of claim 16, wherein, the hard thermoplastic is selected from: a high-density polyethylene (HDPE); and an acrylonitrile butadiene styrene (ABS).
18. The protective headgear of claim 1, wherein the heat absorbing pad is reversibly attached to the underside of the outer shell.
19. The protective headgear of claim 18, wherein the head gear further comprises a suspension system to support the outer shell at a distance from the head of the wearer in order to provide the space there-between.
20. The protective headgear of claim 1, wherein the head gear further comprises a suspension system to support the outer shell at a distance from the head of the wearer in order to provide the space there-between.
21. The protective headgear of claim 20, wherein the heat absorbing pad is comprised within the suspension system.
22. The protective headgear of claim 1, wherein the forced air ventilation apparatus is positioned at the rear of the headgear.
23. The protective headgear of claim 22, wherein, the forced air ventilation apparatus is positioned at the base of the rear of the headgear.
24. The protective headgear of claim 1, wherein, the forced air ventilation apparatus is affixed to the outer shell.
25. The protective headgear of claim 1, wherein the headgear is a hard hat that conforms to National and/or International standards for Impact Protection.
26. The protective headgear of claim 25, wherein the hard hat conforms to American National Standards ANSI/ISEA Z89.1-2009 Type 1, Class G and E.
27. The protective headgear of claim 1, wherein the headgear further comprises a temperature sensor.
28. The protective headgear of claim 27, wherein the temperature sensor controls the actuation and/or speed of the forced air ventilation apparatus.
29. The protective headgear of claim 1, wherein the headgear further comprises a Global Positioning System (GPS) locating transponder.
30. The protective headgear of claim 1, wherein the headgear further comprises a wireless communications system.
31. The protective headgear of claim 30, wherein the wireless communications system is configured so as to communicate local temperature information to a remotely located server.
32. A system for monitoring temperature status information of an individual, in which the temperature status information corresponds to the temperature within a protective headgear of claim 1 that is worn by the individual, wherein the system comprises:
- a temperature sensor located within the headgear;
- a wireless communications transmitter located within the headgear and in communication with the temperature sensor;
- a wireless communications receiver located remotely;
- and a central server that is in communication with the wireless communications receiver,
- wherein, the temperature sensor generates temperature status information and communicates the information to the wireless communications transmitter, which in turn transmits the temperature status information to the remotely located wireless communications receiver, and thus to the central server.
Type: Application
Filed: Feb 24, 2015
Publication Date: Jun 14, 2018
Applicant: Aspire Zone Foundation (Doha)
Inventor: Hilal J. Al Kuwari (Doha)
Application Number: 15/553,401
