ACTIVE COOLING SYSTEM FOR HELMETS

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of the earlier filing date of U.S. Provisional Application No. 63/793,529, filed Apr. 23, 2025, entitled “Active Cooling System for Helmets”, and the priority benefit of the earlier filing date of U.S. Provisional Application No. 63/720,124, filed Nov. 13, 2024, entitled “Active Cooling System for Helmets,” both of which are hereby incorporated herein by reference in their entirety.

FIELD OF INVENTION

Embodiments herein relate generally to a system for active ventilation of helmets, hardhats, and other head protective devices.

BACKGROUND

Helmets are the most effective intervention to reduce the incidence and severity of head trauma. However, in high-temperature environments, helmets can cause thermal discomfort and can attribute to heat stress in workers when performing prolonged strenuous activities. Heat stress arises from hot air being trapped between the head and the helmet shell. In this air space, heat is being radiated from the head surface and the helmet shell. Ventilation of this air space is therefore essential for removal of hot air, and to allow for convective cooling by evaporation of sweat.

Traditional safety helmets have a strap suspension system to absorb impact to the crown from falling objects. Strap suspensions require a large air space between the helmet shell and the head so that the shell can deform during impact without contacting the head. This large air space in turn allows for some natural air flow to prevent excessive heat accumulation.

In contrast, modern helmets employ an impact liner that not only protects the wearer's head from impacts to the helmet crown, but also from lateral impacts to the front, side, and rear. According to the ANSI Z89.1 standard, these modern helmets with lateral impact protection are classified as “Type II” helmets, in contrast to “Type l” helmets without lateral impact protection. Impact liners of Type II helmets typically incorporate 30-50 mm thick rigid Expanded Polystyrene (EPS) foam. Such foam acts as an insulator and prevents heat transfer away from the head. Moreover, these modern helmets also often employ a thin comfort liner made of soft foam to cushion the interface between the head and the rigid foam impact liner. This soft foam liner also prevents air circulation to or around the head. While these modern Type II helmets provide improved impact protection, they can greatly increase heat stress to the user compared to traditional helmets with impact liners. For this reason, improving cooling in Type II helmets with impact liners is of critical importance.

BRIEF DESCRIPTION OF THE DRAWINGS

Several embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings. Embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings.

FIGS. 1A-1B illustrate perspective views of a vented helmet (FIG. 1A) and a fan housing (FIG. 1B) in order to visualize the rear vent openings in the helmet shell over which the fan housing is detachably applied.

FIG. 2 illustrates a perspective view of the fan housing attached to the rear of the vented helmet.

FIG. 3 illustrates a rear view of the fan housing attached to the rear of the vented helmet.

FIG. 4 shows a cross-sectional lateral view of the fan housing and helmet.

FIG. 5 shows a cross-sectional lateral view of the fan housing and helmet in which the cellular impact liner is spaced apart from the helmet shell by means of a spacer.

FIG. 6 shows a cross-sectional side view of the helmet shell in which the fan is used for negative pressure ventilation.

FIG. 7 shows a cross-sectional side view of the helmet shell in which the fan is used for negative pressure ventilation and redirection of the exhaust air back toward the user.

FIG. 8 shows a photograph of a test setup to assess temperature inside a helmet.

FIG. 9 shows a photograph of the helmet inside.

FIG. 10 depicts a graph, showing the temperature inside vented Type II helmets after one hour of sun exposure.

FIG. 11 depicts a graph of the four individual temperature sensor recordings.

FIGS. 12A-12B illustrate a side view (FIG. 12A) and a perspective view (FIG. 12B) of a helmet showing a fan ducting air to a manifold.

FIG. 13 shows a cross-sectional side view of a non-vented helmet shell in which the fan and ducting are mounted to the underside of the helmet brim.

FIG. 14 depicts a graph of trapped heat in a non-vented helmet with and without an attached fan.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration embodiments that may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments is defined by the appended claims and their equivalents.

Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding embodiments; however, the order of description should not be construed to imply that these operations are order dependent.

The description may use perspective-based descriptions such as up/down, back/front, and top/bottom. Such descriptions are merely used to facilitate the discussion and are not intended to restrict the application of disclosed embodiments.

The description may use the terms “embodiment” or “embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments, are synonymous.

Embodiments herein relate generally to a system for active ventilation of helmets, hardhats, and other head protective devices, referred to collectively herein as helmets. Specifically, one or more fan units can be positioned over or adjacent to vent openings of a helmet shell. Such fan units can be powered by batteries, whether replaceable or rechargeable, and/or may have solar cells and thus be solar powered. In conjunction with an impact liner having one or more voids (for example made from expanded polystyrene (EPS) or expanded polypropylene (EPP)), fan units can actively force air through the vent opening of the helmet shell and through the voids of the impact liner to cool the head surface. In conjunction with an optional spacer between the impact liner and the helmet shell, air flow supplied by the fan can be distributed over a large circumferential space around the head for evenly distributed low-pressure ventilation. The fan may be operated to induce positive or negative pressure inside the helmet.

In the case of positive pressure ventilation, this venting system and method does not require external air ducting around the outer edge of a helmet shell, but instead delivers an evenly distributed low-pressure air flow around the head for effective and comfortable cooling.

In the case of negative pressure ventilation, the fan is positioned to draw air from inside the helmet and vent it to the outside environment. For negative pressure ventilation, an external vent or duct may redirect the exhaust air toward the user for additional air flow and cooling.

While it is noted above that ducting is not needed, a fan may be located on a helmet in a location (such as away from the vents) necessitating the use of ducting to direct air into the helmet or draw air out of the helmet. As such, venting can be used to enable positioning the fan in a greater number of locations, and to distribute air flow as desired.

In an embodiment, a fan unit may be deployed on non-vented helmets, such as by mounting a fan on or near the brim of a helmet with ducting to direct air into the helmet or to draw air out of the helmet.

It is thus an objective herein to provide a system for cooling a wearer's head when wearing a modern safety helmet with an impact liner to combine the benefits of improved impact protection provided by an impact liner and improved cooling to reduce heat stress. Thus, embodiments herein address the problem of increased heat stress observed with modern safety helmets that have an impact liner made of insulating foam that may trap heat inside the helmet. An advantage achieved by embodiments herein is to reduce heat stress associated with modern Type II safety helmets while retaining the ability of lateral impact damping by means of an impact liner.

An objective of embodiments herein is attained by a system comprising a fan unit that is mounted to a helmet shell over or adjacent to one or more vents present in the helmet shell. The fan unit generally contains a housing and one or more fans, and may include elements or features to direct airflow, such as ducting, or may be positioned in such a way that ducting is not needed. The fan unit may be connected to the helmet, or may be detachable such that the fan unit can be coupled and uncoupled from the helmet as desired by the user. Attaching or coupling the fan unit to the shell rather than integrating it into the shell retains the structural integrity of the shell, and permits the concepts described herein to be applied to a greater number of helmets.

In an embodiment, the fan unit/housing may be detachably coupled to the helmet using straps, brackets, snaps, hooks, rails, hook-and-loop fastener, and other known mechanisms. In other embodiments, the fan unit/housing may be connected to the helmet shell by one or more fasteners (such as screws).

In embodiments, the impact liner may be referred to as having voids, whether such voids are formed during or after manufacture, and whether they are in the form of small holes or perforations or larger open spaces. The voids are configured to permit the passage of air therethrough. As examples, the impact liner inside the shell may be made of an open-cell material or an at least partially perforated polymeric foam material that can absorb impact energy while allowing air to flow through it. As an example, an impact liner may have an organized cellular structure such as a honeycomb or an array of interconnected cells that allows air flow through its cellular structure. As another example, the impact liner may be shaped as a ring or other similar shape, which has an impact absorbing region and a large singular void positioned toward the crown of the helmet.

The impact liner may be arranged such that the voids of the impact liner are at least partially aligned with the one or more apertures of the shell, such that there is a pathway for airflow between the outside environment and the interior of the helmet at least through the aligned apertures and voids.

In embodiments, a spacer may be mounted between the impact liner and the helmet shell to create a cavity, such as a circumferential cavity, around at least a portion of the head. This spacer is preferably installed in proximity to the helmet crown. The cavity allows air flow supplied by the fan to be distributed over a large, generally circumferential space around the head, which subsequently flows through the impact liner toward the head for evenly distributed low-pressure ventilation.

In embodiments, a suitable spacer may be about 0.5-3 inches thick, and about 2-4 inches in circumference or its long dimension. The noted dimensions are exemplary, and embodiments herein are not limited to those dimensions unless specified.

This ductless venting arrangement can therefore induce circumferentially distributed low-pressure air flow through a shell and impact liner onto a user's head for even and comfortable cooling.

Standard vented helmets typically have a multitude of small vent openings distributed throughout the helmet shell. In an embodiment, a fan unit may be coupled to the helmet shell to be fully or partially aligned with, or in proximity to, one or more of the vent holes.

In an embodiment, the vent area in the shell over which the one or more fan units are mounted may be significantly larger than other vent holes in the helmet shell, and, optionally, larger than the sum of all other vent holes in the helmet shell, in order to direct the air flow through the impact liner toward the head. In one embodiment, the shell may only have vent openings at the location to which the fan unit is attached, so that all air flow created by the fan unit is directed through those vent openings.

In one embodiment, one or more fan units are detachably coupled to the outside of the protective shell. In an embodiment, the fan(s) may be aligned with vent hole(s), if present, or may be adjacent to the vent hole(s). A fan unit may include a housing, one or more fans, and, optionally, ducting or other features to direct air.

In an embodiment, air can be blown directly into or out of the helmet without the need for external ducting. In an embodiment, a helmet may be used that has no or minimal venting ducts. In alternative embodiments, a fan unit may be provided with ducting, or may couple to ducting present on or in the helmet.

In the presence of an impact liner having one or more voids, air flow can pass through the voids in the impact liner and onto the user's head for cooling. As an example, air from an associated fan can flow through the vent opening of the helmet shell through the voids of an impact liner, such as a partially perforated polymeric foam impact liner, and to the user's head for cooling.

In an embodiment, an air space may be created between the outer shell and at least a portion of the impact liner by means of a spacer. Spacing an impact liner away from the shell is highly counterintuitive, since helmets typically apply impact liners directly onto the inside of the helmet shell to minimize helmet size, and to facilitate load transfer during an impact. In an embodiment, such a spacer may be located at the crown of the helmet to create a circular air space around the spacer and thus around the inside of the helmet. This in turn allows air to be distributed around the inside of the helmet before advancing through the impact liner toward the head surface. As such, this embodiment may distribute air through one or more vents over a wider area on the head. Moreover, in case of an impact liner with regular cell geometry, such as a honeycomb, the air from the air space can be directed through the cellular liner in a laminar flow pattern perpendicular to the surface of the head.

In an embodiment, the spacer between the impact liner and the shell may be shaped to guide, split, or distribute airflow throughout the air space created by the spacer to improve the distribution of air flow and to eliminate hot spots inside a helmet.

In an embodiment, the fan may be actuated in a bi-directional manner to either blow air into the helmet or to evacuate air from the inside of the helmet to the outside environment.

In an embodiment, the fan speed may be adjustable for rapid or slow air flow.

In an embodiment, a fan unit may include a filter or screen on the air inlet or outlet to prevent debris from being blown into the helmet or drawn into the fan unit.

In an embodiment, two or more fan units may be used and positioned in different locations on the helmet, whereby the fans are positioned to blow air in the same direction or to move air generally in the same flow path. Alternatively, one or more fans may blow air into the helmet, while one or more additional fans may draw air out of the helmet to induce conductive air flow in and out of the helmet.

In an embodiment, the fan unit/housing may be coupled to the outside of the helmet with a polymeric intermediate layer to suppress noise transmission from the fan to the shell.

In embodiments, one or more sensors may be provided on or in the fan unit, or on or in the helmet and electrically or wirelessly connected to the fan unit. The sensors may be used to monitor conditions such as temperature and humidity. In an embodiment, the fan unit may be configured to be responsive to the sensor data, such that the fan may operate automatically, or the fan speed may be adjusted automatically, as a result of the detection of a temperature or humidity level above a set threshold.

In another embodiment, the fan may be operated to induce negative pressure inside the helmet by drawing air through the helmet vent(s) to the outside of the helmet. Negative pressure ventilation prevents heat accumulation underneath the helmet (close to the head), while preventing debris and dust from being blown into the helmet. In an embodiment using this negative pressure ventilation, the fan unit may be ducted to redirect the exhaust air toward the user for additional air flow and cooling.

This two-stage cooling approach is not only novel but also counter-intuitive. In the first stage, warm air underneath the helmet shell is gradually and evenly evacuated to the outside by means of a vent to reduce the temperature underneath the shell. In a second stage, this warm air is redirected by a duct toward the user, likely the user's neck. While it would be counterintuitive to blow warm air to achieve cooling, evaporative cooling is achieved by directing air flow over the neck skin in the presence of perspiration. In combination, this two-stage cooling system prevents excessive temperature increases inside the helmet shell, and in addition provides a noticeable air flow over skin for a cooling sensation.

FIGS. 1A-1B illustrate perspective views of a fan unit 16 having a housing 1 separate from a vented helmet 2 with apertures 3 at the rear aspect of the helmet that serve as vents for cooling. Helmet 2 has side rails 4 to facilitate attachment of accessories, such as the fan housing 1 of fan unit 100.

FIG. 2 illustrates a perspective view of the fan housing 1 attached to the vented helmet 2 directly over the rear apertures 3, so that air can directly flow from the fan housing 1 through the apertures 3 without the need for ducting. Fan housing 1 contains one or more fans 7 (better seen in FIG. 3) and louvres 8. Fan housing 1 is secured by straps 5 that are detachably connected by means of brackets 6 that can be connected to the rear end of side rail 4. While straps 5 and brackets 6 are shown in FIG. 2, it should be understand that other means of coupling the fan housing 1 to helmet 2 are included within the description herein. Such couplings may take the form of snaps, hooks, rails, hook-and-loop fastener, and other known mechanisms.

While not evident from FIG. 2, a polymeric or sound-damping intermediate layer may be present between fan housing 1 and the helmet shell to suppress noise transmission from the fan to the shell.

FIG. 3 illustrates a rear view of the fan housing 1 attached to the vented helmet 2 directly over the rear apertures 3. The fan housing 1 may contain one or more battery-powered fans 7. The one or more fans are protected inside the fan housing 1 by louvres 8 on the outside of fan housing 1, which are also positioned to permit the passage of air drawn into the fan housing 1 by operation of the fan(s) 7. If powered, fan 7 can direct air flow into helmet 2 or draw air out of helmet 2. In the case where the fan 7 is configured to blow air into the helmet 2, a filter may be added to the fan to prevent debris from being blown into the helmet.

FIG. 4 shows a cross-sectional side view of the fan housing 1 attached to helmet 2. Inside helmet 2 is an impact liner 9 made of structure having one or more voids 17 through which the one or more fans 7 can pass and circulate air directly into or out of the helmet. One or more batteries 10 are located within fan housing 1 to power the fan. The fan housing 1 may also contain ancillary electronics and hardware for fan control, such as speed control, direction control, a charging port, and an on-off switch. Fan housing 1 or the helmet shell 2 may also contain photovoltaic panels for battery charging.

FIG. 5 shows a cross-sectional side view of the fan housing 1 attached to helmet 2. Impact liner 9 is spaced apart from portions of the helmet shell by means of a spacer 11. This spacer 11 may be located at the helmet crown or at any other location adjacent to the helmet shell. Spacer 11 creates an unfilled cavity 12 between the helmet shell and the impact liner 9. This arrangement enables air to flow and distribute between impact liner 9 and the helmet shell, such that air flow is distribute over an expanded section of the impact liner 9 before proceeding through the impact liner 9 toward the head. For example, air that is being forced into cavity 12 by a rear-mounted fan 7 can freely flow around spacer 11 to the front of the helmet toward frontal location A where impact liner 9 contacts shell 2, at which point air can proceed toward the head through impact liner 9. Without spacer 11, air flow would be focused solely or at least preferentially on the area adjacent to the apertures under fan housing 1. Conversely, spacer 11 delivers more even and distributed air circulation around the head.

FIG. 6 shows a cross-sectional side view of the fan 7 and fan housing 1 attached to the helmet shell 2. In case of negative pressure ventilation, fan 7 draws air from helmet cavity 12 through the shell 2 to the outside. The exhaust air B is thus vented through the fan housing 1 to the outside environment.

FIG. 7 shows a cross-sectional side view of the fan 7 and fan housing 1 attached to the helmet shell 2. In case of negative pressure ventilation, fan 7 draws air from helmet cavity 12 through the shell 2 to the outside. The exhaust air C is vented through the vent housing 1 and through duct 13. This duct 13 redirects exhaust air around the lower edge of shell 2 and directs the exhaust air C toward the user for additional air flow and cooling.

FIG. 8 shows a photograph of a test setup to assess temperature inside a helmet. A heated headform 18 is kept at a constant temperature of 37° C. An external heat source 14 simulates constant exposure to sunlight.

FIG. 9 shows a photograph of the helmet inside, with the impact liner removed to visualize four temperature sensors 15 mounted inside the helmet. These sensors measure the steady state temperature in each helmet quadrant after 1 hour of constant simulation of sunlight exposure by means of the external heat source (as shown in FIG. 8).

FIG. 10 depicts a graph, showing the temperature inside vented Type II helmets after one hour of sun exposure, averaged for the four temperature sensors. A vented helmet with an open-cell impact liner (CELL) is 6° C. cooler than a vented helmet with a closed-cell EPS foam liner (FOAM). Adding a fan with a low-speed setting of 8.4 m³/hour cfm and 1.4 m/s air flow to the CELL helmet (CELL+LOW FAN) reduced the average temperature by an additional 8° C. Increasing the fan speed to yield an air flow of 18.5 m³/hour and 3.0 m/s decreased the temperature only 1° C. more (CELL+HIGH FAN).

FIG. 11 depicts a graph of the four individual temperature sensor recordings for the type II vented helmet with an open-cell impact liner (CELL), and for the same helmet with the added fan (CELL+LOW FAN). Without the fan, sensor recordings varied by 14° C., ranging from 26° C. to 40° C. With the fan, sensor recordings only varied by 4° C., ranging from 24° C. to 28° C. Hence, in addition to lowering the average temperature inside the helmet, the fan also reduced temperature variations within the helmets for even cooling.

FIGS. 12A-12B illustrate a side view (FIG. 12A) and a perspective view (FIG. 12B) of a helmet/shell 2 showing a fan 7 ducting air through ducting 13 to a manifold 19. While manifold 19 is not necessary, when present, it provides a centralized distribution point for the air provided by fan 7 to then be directed through certain vents (not shown) in helmet/shell 2. This arrangement also allows one or more fans, such as fan 7, to be positioned away from the vents through which air is directed.

FIG. 13 shows a cross-sectional side view of a non-vented helmet shell 2 in which the fan housing 1, containing fan 7, and ducting 13 are mounted to the underside of the brim of helmet shell 2. While mounted to the underside of the helmet in FIG. 13, the fan housing 1 can be mounted inside or outside of helmet shell 2, as desired. Ducting 13 is configured to draw air through the impact liner 9 and/or from cavity 12 toward the outside environment. The exhaust air from the system may be directed to the outside, or may be directed back to the wearer.

FIG. 14 depicts a graph of trapped heat (in Watts) in a non-vented helmet with and without an attached fan. FIG. 14 shows the effect of adding a fan to the underside of the brim of a non-vented helmet, whereby the fan pulls air from underneath the helmet. As can been seen from the data, using a fan on a non-vented helmet prevents heat trapping.

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. Specifically, the disclosed invention may be practiced with different helmet types and styles, over a range of different fan and vent aperture configurations. It is understood, therefore, that this disclosure is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present disclosure as defined by the appended claims.

Although certain embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope. Those with skill in the art will readily appreciate that embodiments may be implemented in a very wide variety of ways. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that embodiments be limited only by the claims and the equivalents thereof.