The purpose of the present invention is to provide a safety helmet for riders of two wheelers with a provision for ventilation by means of suction by a venturi which is integral with the outer shell of the helmet.
It is well known that the safety helmets for motor-cyclists and in general for those who
take part to sport contests which require the use of a safety helmet, are made in the form
of a complete cap which, in case of integral helmets, is provided in its front side, in
correspondence of the user's eyes, with an opening which can be closed by means of a lift
able and/or removable transparent visor.
The helmets are normally provided with an external cap or shell, made from a rigid and
strong material, such as polycarbonate, or the like, or composite materials, inside which a
safety padding is coupled, e.g., made from polystyrene or foamed polyurethane; with this
safety padding a lining is then associated, which is made from a soft material, which
constitutes a comfort padding.
Analogous structures are displayed as well by the helmets of the open type, commonly
named either "Jet" or "Demijet" helmets. The integral helmets, above all due to their
particular enclosing structure, involve the need of being internally ventilated by causing
an air stream to circulate inside them, in order to prevent the helmet user's head from
overheating, and condensate to be formed due to the user's perspiration. In order to
accomplish a proper ventilation inside the helmet, several solutions were proposed in the
past, which are substantially based on the principle of intaking an air stream from the
outside by means of bores or openings provided in the front portion of the helmet, of
making said air stream circulate through the padding layers by means of suitable,
variously shaped and positioned air channels, and of subsequently venting said air stream
from the rear portion of the same helmet, in the nearby of the user's nape, or anyway of
the user's occipital region.
A Furopean Patent no. 320622 discloses a form of .safety helmet which is known well.
and is provided with frontal air intakes, in the lowest frontal portion thereof, with air flowing inside the helmet and being vented to the outside both from the side portions of the helmet, and from the top of the cap wherein an inclined guide fin, positioned ahead of air intakes provided in the same cap, creates such a depressure as to cause the warm air inside the helmet to be sucked towards the external atmosphere.
Furthermore, inasmuch as at high speeds the air stream flowing inside the air channels is verv fast, conditions mav ari.se. which are troublesome for the driver's face and eves, as well as undesirable air jets may be established in the driver's occipital region. Therefore, a purpose of the present invention is to provide a safety helmet equipped with air suction means external to the same helmet, which are given such a structure as to favour the expulsion of the warm air built up inside the helmet during the u.se thereof, and, in particular, at the low speeds, during which heat tends to accumulate to a larger extent, owing to the very limited heat exchanges, thus overcoming all the disadvantages and troublesome feelings affecting the ventilation systems known from the prior art.
However, the helmet as disclosed in the prior art has the following shortcomings.
Since the fin assembly is not integral with any helmet, it must be assembled by the user. This however may prove to be a somewhat comnlpx prppess for a layman-
Further the curyature and dimensions of the outer shell differ from model to brand to brand and even between different models of the same brand. Hence the effectiveness if the pxisting gadget will vary with different helmets.
The assembly being of temporary nature has chances of unfastening due to incorrect assembly especially at high speeds.
Also additional weight of the fin assembly must be taken by the user which will cause added discomfiture.
Projection of "slider body" (adjusting lever) above the outer shell may exceed the permitted value of 5mm as prescribed by BIS.
With reference to the construction no diffuser is provided for smooth outlet of air from within the helmet.
The helmet was not designed keeping in mind the hot and humid conditions in India.
People are forced to wear bandanas, scarves etc.
under the helmet. Complaints of hair loss due to excessive sweating have also emerged.
Accordingly a safety helmet for the use of motorcyclists and the like comprising a hollow protrusion being made integral and continuous with helmet outer shell,said hollow protrusion being made in the form of a first converging nozzle, diverging diffiiser portion and a throat being formed in between the converging nozzle and the diverging diffiiser portion ( referred to as venture (2) ), at the underside, the upperside of the said hollow protrusion being conforming to the outer shell of the said helmet;atleast one slot (4) being provided in the protective padding (3) of the helmet;the said slots (4) being made directly under throat area (2b) of the said venture; so that when the velocity of air increases, the pressure in the throat (2b) decreses creating suction of air from the interior of the helmet which is expelled through the outlet of the venturi(2).
Therefore the main object of this invention is to provide a helmet which is more
conducive to tropical conditions.
This has been achieved by providing a means to replace hot air inside the helmet by
relatively cooler atmospheric air.
Another objective of this invention is to provide a helmet which is more comfortable and
easy to use.
Yet another objective of this invention is to provide a helmet which is cost effective and
obviates the shortcomings of the previous inventions.
On the top of the helmet, a hollow protrusion has been created. It is shaped as a venturi i.e. it has a converging nozzle followed by a diverging diffuser portion. It will be made integral and continuous with the outer shell.
The ventilation is provided in the following manner. The outer shell of the helmet has an external projection with a divergent convergent section and a convergent divergent section (referred to as venturi) at the underside (with the area of least cross section being referred to as throat) and the upper side conforming to the shape of the outer shell (so as to reduce stress concentration). The venturi is open at both the ends and due to reduction in area at the throat, the velocity of the air increases, thereby reducing the pressure and creating suction at the throat. There are slots provided in the EPS layer of the helmet at the position corresponding to the throat. Due to the decrease in local pressure, there is suction of air from the interior of the helmet. The air is now expelled through the outlet of the venturi.
The advantage of the present invention is that since the vent is made integral with the outer shell, there are no problems such as alignment and adjustment as associated with external ventilation devices.
A fiirther objective of the present invention is to provide a helmet which is simple and cheap to manufacture, aesthetically pleasant, and also applicable, without any substantial modifications, to the already known and existing helmet types.
Provision for a slider to close the vent in winters and monsoons to prevent cold air and water from entering the helmet can be made. The inner surface will be made smooth to avoid losses due to turbulence. Rounding of the hollow protrusion at the entry and exit of the venturi can be done to mininmise entrance and exit losses. Plastic inserts are placed within the protective layer slots so as to ensure smooth flow of air.
On the top of the helmet, a hollow protrusion has been created. It is shaped as a venturi i.e. it has a converging nozzle followed by a diverging diffuser portion. It is made integral
with the helmet outer shell and will be made integral and continuous with the outer shell. Further the material of the protrusion and the helmet outer shell will be homogenous.
The ventilation is provided in the following manner. The outer shell of the helmet has an external projection with a divergent convergent section and a convergent divergent section (referred to as venturi) at the underside (with the area of least cross section being referred to as throat) and the upper side conforming to the shape of the outer shell (so as to reduce stress concentration). The venturi is open at both the ends arid due to reduction in area at the throat, the velocity of the air increases, thereby reducing the pressure and creating suction at the throat. There are slots provided in the EPS layer of the helmet at the position corresponding to the throat. Due to the decrease in local pressure, there is suction of air from the interior of the helmet. The air is now expelled through the outlet of the venturi.
Description of the present invention with respect to drawings:
Figure 1 shows the schematic sectional side view of the helmet taken through the central
plane A-A.
Figure 2 and 3 respectively show the schematic top and front view of the helmet.
Figure 4 shows the schematic sectional rear view of the helmet taken along plane B-B.
Referring to attached figures, the depicted helmet comprises of an outer shell (1), an external projection (2) with inlet for air (2a), throat section (2b), and outlet (2c), protective layer (3), protective shield also called visor(5), lower face (jaw) cover (6), and comfort padding or liner(7). Inside the helmet, in the EPS layer (3), slots (4) are provided located under the throat of the venturi (2b).
The outer shell (1) is a rigid external cap made of polycarbonates, composite materials, or the like. The protective layer is made of foamed material, or the like, such as foamed polystyrene or polyurethane. The comfort lining (7) is made of a soft material.
According to the invention the ventilation is provided in the following manner. The air enters the protrusion (2) through the inlet (2a). Due to reduction in area at throat (2b), there is a reduction in pressure and heqce air is sucked out from the interior of the helmet through the slots in the EPS (4). This air is expelled out through the outlet (2c).
The materials and dimensions described in the specifications are only illustrative in nature and in no way are they intended to restrict the scope of the invention.

We claim:
1. A safety helmet for the use of motorcyclists and the like comprising a hollow protrusion being made integral and continuous with helmet outer shell,said hollow protrusion being made in the form of a first converging nozzle, diverging diffuser portion and a throat being formed in between the converging nozzle and the diverging diffuser portion ( referred to as venture (2) ), at the underside, the upperside of the said hollow protrusion being conforming to the outer shell of the said helmet;atleast one slot (4) being provided in the protective padding (3) of the helmet;the said slots (4) being made directly under throat area (2b) of the said venture; so that when the velocity of air increases, the pressure in the throat (2b) decreses creating suction of air from the interior of the helmet which is expelled through the outlet of the venturi(2).
2. A safety helmet as claimed in preceding claim, wherein the hollow protrusion is integral with the outer shell.
3. A safety helmet as claimed in preceding claim wherein outer shell of the helmet and hollow protrusion are purposely made of the same material.
4. A safety helmet as claimed in the preceding claim wherein shutters are provided to prevent entering of the cold wind or water.
5. A safety helmet where the inner surface of the said hollow protrusion is made very smooth to prevent losses due to turbulent flow of air.
6. A safety helmet wherein the entrance and exit of the vents have been rounded off' to minimise entrance and exit losses.
7. A safety helmet wherein lightweight, hollow, cylindrical, inexpensive replaceable plastic inserts are placed within the EPS slots to ensure smooth flow of air.
8. A safety helmet which can be easily maintained at minimal cost by replacement of plastic inserts in the EPS slots, in case of clogging and plugging of holes.
9. A safety helmet substantially described in the specification and illustrated in the
drawings.