Patent Publication Number: US-10314359-B2

Title: Moisture displacement system for a visor

Description:
FIELD OF THE INVENTION 
     This invention relates to a visor for a helmet, a helmet incorporating a visor, and a moisture displacement system for a visor. 
     BACKGROUND TO THE INVENTION 
     A helmet, such as a motorcycle helmet, typically has a body portion and a visor. The body portion is formed from a padded portion and an outer shell, the padded portion being formed from a material suitable for absorbing an impact. In use, the helmet body fits over the head of a user, for example a motorcyclist, and the padded portion rests against the user&#39;s head. The helmet body typically has an opening which provides a viewing window for the wearer, and which is covered by a clear visor. In a typical motorcycle helmet, the visor is pivotally mounted to the body of the helmet such that it can be lifted from a first position, in which the visor is positioned in front of the wearer&#39;s eyes, into a second position, in which the visor is located above the opening of the viewing window. 
     A common problem for motorcyclists wearing helmets is that, when riding a motorcycle through precipitation, such as rain, water or mist droplets tend to form on an outer surface of the visor, which can obscure the vision of the rider. 
     When the rider is travelling at high speeds, the water and mist droplets tend to be urged towards side and bottom edges of the visor by the air hitting the visor. However, when the rider is travelling at low speeds, the air hitting the visor is typically not powerful enough to cause the water droplets to be forced to the edges of the visor. In order to regain clear vision through the visor, the rider typically has to use his or her hand or arm to wipe away the water droplets from the visor, or to lift the visor up so that the water droplets no longer obscure the view of the rider. However, it will be apparent that, if the visor is moved out of the line of vision of the rider, then wind and rain could blow into the rider&#39;s face, potentially further obscuring his or her view. 
     SUMMARY OF INVENTION 
     A first aspect of the invention provides a visor for a helmet, the visor comprising: an air delivery element for delivering air to a surface of the visor, the air delivery element comprising: a first channel for receiving air from an air source; a second channel having an outlet through which air is transportable to the surface of the visor; and a connector channel for connecting the second channel in fluid communication with the first channel. 
     The first channel, the second channel and the connector channel may be substantially circular in cross section. A cross sectional area of the connector channel may be smaller than a cross sectional area of the first channel and/or the second channel. The first channel and the second channel may be arranged substantially parallel to one another. The connector channel may be arranged substantially perpendicular to the first channel and/or to the second channel. 
     The outlet may comprise a slit. 
     The first channel may be formed within the visor, such that no portion of the first channel protrudes beyond the surface of the visor. The second channel may be formed in a lip which protrudes beyond the surface of the visor. 
     The visor may further comprise a ridge formed on the surface of the visor adjacent to the outlet, configured to create a Coanda effect in air passing through the outlet. 
     The outlet may be configured such that air can exit the outlet in a direction substantially parallel to the surface of the visor adjacent to the outlet. 
     The first channel may have a first end and a second end. Air from the air source may be received via the first end, and the second end may comprise an air barrier to prevent the flow of air beyond the second end of the first channel. 
     The visor further comprise a connector for connecting the visor to a helmet. The connector may be configured such that, when the visor is connected to a helmet, the visor is movable between a first configuration in which the transport of air via the connector to the air delivery element is permitted, and a second configuration in which the transport of air via the connector to the air delivery element is restricted. The connector may be a pivotable connector for pivotally connecting the visor to a helmet. 
     A second aspect of the invention provides a visor for a helmet, the visor comprising: an air delivery element for delivering air to a surface of the visor, the air delivery element comprising: at least one inlet for receiving air from an air source; and a plurality of outlets through which air is transportable to the surface of the visor; and a ridge formed adjacent to the plurality of outlets for creating a Coanda effect in air passing through the plurality of outlets. 
     The visor may further comprise a connector for connecting the visor to a helmet. The connector may be configured such that, when the visor is connected to a helmet, the visor is movable between a first configuration in which the transport of air via the connector to the air delivery element is permitted, and a second configuration in which the transport of air via the connector to the air delivery element is restricted. 
     The connector is may be a pivotable connector for pivotally connecting the visor to a helmet. 
     The at least one inlet may comprise: at a first end, a first inlet for receiving air from an air source; and at a second end, a second inlet for receiving air from the air source. 
     A third aspect of the invention provides a visor for a helmet, the visor comprising: an air delivery element for delivering air to a surface of the visor; a connector for connecting the visor to a helmet; and a channel formed in the connector for transporting air from an external source via the connector to the air delivery element; wherein the connector is such that, when the visor is connected to a helmet, the visor is movable between a first configuration in which the transport of air via the connector to the air delivery element is permitted, and a second configuration in which the transport of air via the connector to the air delivery element is restricted. 
     The connector may be a pivotable connector for pivotally connecting the visor to a helmet. 
     The air delivery element may be a manifold and comprises: at a first end, a first inlet for receiving air from an air source; at a second end, a second inlet for receiving air from the air source; and a plurality of outlets through which air is transportable to the surface of the visor. 
     The visor may further comprise a ridge formed adjacent to the plurality of outlets for creating a Coanda effect in air passing through the plurality of outlets. 
     A fourth aspect of the invention provides a helmet comprising: a body; and a visor as described above. 
     The helmet body may comprise a padded portion and an outer shell. The helmet may comprise a helmet conduit for delivering air to the air delivery element. The helmet conduit may be mounted within the shell. The helmet conduit may be at least partially embedded within the padded portion of the helmet body. 
     The helmet conduit may comprise an inlet for receiving air from an air source, and at least one outlet for delivering air to the air delivery element. The helmet conduit may comprise a first outlet for delivering air a first end of the air delivery element, and a second outlet for delivering air a second end of the air delivery element. The helmet conduit may be formed integrally with the helmet body. 
     A fifth aspect of the invention provides a moisture displacement system for a helmet visor, the moisture displacement system comprising: a helmet as described above; an air source; a conduit for transporting air between the air source and the helmet. The air source may comprise an air pump. The air source may be mountable to a vehicle. The air source may be configured to receive power from the vehicle, and may be controllable using a controller formed integrally with, or mounted on, the vehicle. The conduit may be detachably connectable to the helmet. 
     It will be appreciated that the features of the various aspects of the invention may be combined with those of other aspects of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described, strictly by way of example only, with reference to the accompanying drawings, of which: 
         FIG. 1  is a side view of a motorcycle and a motorcyclist wearing a helmet and visor constructed in accordance with an embodiment of the invention; 
         FIG. 2A  is a side view of a helmet constructed in accordance with an embodiment of the invention, the helmet being in a first configuration; 
         FIG. 2B  is a side view of the helmet of  FIG. 2A  in a second configuration; 
         FIG. 3  is a perspective view of a body of the helmet of  FIGS. 2A and 2B ; 
         FIG. 4  is a perspective view of a visor of the helmet of  FIGS. 2A and 2B ; 
         FIG. 5  is a sectional view of a mechanism for connecting the visor of  FIG. 4  to the helmet body of  FIG. 3  according to a first embodiment of the invention; and 
         FIG. 6  is a side view of a mechanism for connecting the visor of  FIG. 4  to the helmet body of  FIG. 3  according to a second embodiment of the invention; 
         FIG. 7  is a side view of the mechanism of  FIG. 6 , connected to the visor of  FIG. 4 ; 
         FIG. 8  is a sectional view of a portion of a moisture displacement system constructed in accordance with an embodiment of the invention; 
         FIG. 9  is a perspective view of a visor constructed in accordance with a further embodiment of the invention; 
         FIG. 10  is a side view of the visor of  FIG. 9 ; and 
         FIG. 11  is a front view of the visor of  FIGS. 9 and 10 . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Referring to the drawings,  FIG. 1  shows a motorcycle  10  and a rider  12  on the motorcycle. It will be appreciated that, while the invention is described, in this embodiment, in the context of a motorcyclist  12  riding a motorcycle  10 , the invention is applicable to other vehicles such as scooters, bicycles, karts, cars, buggies, and the like. 
     The motorcycle  10  includes a rear wheel  14 , a front wheel  16 , a motorcycle body  18  and handle bars  20 . It will be appreciated that the motorcycle  10  includes a number of additional components which are not essential for understanding this invention. For example, the motorcycle also includes an engine (not shown) located within the body  18 . 
     The rider  12  wears a helmet  22  formed of a helmet body  24  and a visor  26 . The construction of the helmet  22  will be discussed in more detail with reference to  FIGS. 2 and 3 . A port  28  extends from a base of the helmet body  24  of the helmet  22 , and is connected to an air pump  30  via tubing, or an umbilical  32 . The umbilical  32  is formed from flexible material, such as rubber, and is coupled at a first end to the air pump  30 , and at a second end to the helmet  22  via the port  28 . The air pump  30  is configured to pump air along the umbilical  32  to the helmet  22 . The port  28  is connected to a manifold, or air delivery element,  34  which is mounted on, or formed integrally with, the visor  26 . A connection is formed between the port  28  and the air delivery element  34  for delivery of the pumped air to the air delivery element, as will be discussed with reference to  FIGS. 2 and 3 . 
     In use, air from the air pump  30  is pumped along the umbilical  32  to the air delivery element  34 . The air delivery unit  34  directs the air onto a surface of the visor  26  and serves to displace moisture, such as water or mist droplets, present on the surface of the visor  26  which may be obscuring the view of the rider. 
     In this embodiment, the air pump is configured to pump the air in a pulsed manner. In other embodiments, however, the air pump  30  may pump air in a continuous manner. The pulsed air delivery is preferred, since pulsed air is more effective in removing moisture from the visor. 
     The helmet  22  will now be described in greater detail with reference to  FIGS. 2 and 3 .  FIGS. 2A and 2B  are side views of the helmet  22 . The visor  26  is pivotally connected to the helmet body  24  by a pair of connectors  36  (only one connecter is visible in  FIGS. 2A and 2B ). The connectors  36  allow the visor  26  to be moved between a first, closed configuration, as shown in  FIG. 2A , and a second, open configuration, as shown in  FIG. 2B . A motorcyclist  12  typically uses a helmet  22  in the closed configuration shown in  FIG. 2A  when he or she is riding a motorcycle  10 , as the visor  26  acts as a barrier for preventing wind, moisture and debris from entering his or her eyes. When the motorcycle  10  is not in motion, for example when the motorcyclist has reached his or her destination, then he or she might move the visor  26  into the second, open configuration, as shown in  FIG. 2B . 
     In some embodiments, the connectors  36  are formed integrally with the helmet body  24 . In other embodiments, the connectors  36  are separate units which are configured to fit into complementary apertures or recesses formed in the helmet body  24 . 
     The umbilical connection port  28  is located on one side of the helmet  22 , adjacent to the base of the helmet. In this description, the base of the helmet is considered to be that part of the helmet in which is formed an opening for receiving the head of the motorcyclist  12 . In other words, the port  28  is located at a lower side of the helmet such that, in use, the port  28  is relatively close to the motorcycle  10 . The port  28  may be any known port or means for connecting together two portions of pipe or tubing. For example, the port  28  may be any snap-fit connector. Ideally, the port  28  is configured to receive the umbilical  32  by pushing the umbilical into the port. The act of pushing the umbilical  32  into the port  28  causes the umbilical to snap into place, for example with a click so that a user can identify when the umbilical has been fitted correctly into the port. The port  28  is also preferably configured such that the umbilical  32  is releasable from the port if sufficient force is applied. For example, if the umbilical  32  is pulled in a direction substantially downwards or sideways from the port  28 , then the umbilical can break away from the port, thereby disconnecting the umbilical from the helmet  22 . This arrangement acts as a safety mechanism so that, if the motorcyclist  12  is involved in an accident, whereby he or she falls off the motorcycle  10 , then the umbilical  32  is released from the port  28 , preventing any restriction on the movement of the motorcyclist&#39;s head. 
     With reference again to  FIG. 1 , the umbilical  32  is shown connected to the air pump  30  which is attached to the motorcycle  10 . The umbilical  32  may be connected to the air pump using a port similar to the port  28  described above. Alternatively, a more permanent connection may be used. In some embodiments, the umbilical  32  is stored wound on a reel  38 . The reel  38  is an auto-winding reel, which is configured to automatically wind the umbilical  32  when the umbilical is not in use. When a motorcyclist  12  needs to connect the umbilical  32  to his or her helmet  22 , he or she pulls the umbilical towards the helmet, thereby unwinding the umbilical from the reel  38 . When the umbilical  32  has been unwound to a sufficient length, the motorcyclist  12  can plug the umbilical into the port  28  on the helmet  22 . When a connection between the umbilical  32  and the helmet  22  is no longer required, such as at the end of a ride, the motorcyclist releases the umbilical from the helmet, and allows the reel  38  to automatically wind up the umbilical for storage. 
     While, in  FIG. 1 , the reel  38  and the air pump  30  are shown mounted to the rear of the motorcycle  10 , it will be appreciated that either or both of the air pump and the reel may be mounted elsewhere on the motorcycle, particularly on the body  18  of the motorcycle. In some embodiments, the air pump  30  is configured to receive power from the engine of the motorcycle. In other embodiments, however, the air pump  30  receives power from an auxiliary power source, such as a battery (not shown) mounted on the motorcycle  10 . 
     Referring again to  FIGS. 2A and 2B , the port  28  is shown in fluid communication with the connector  36  via a helmet conduit  40 , denoted by a dashed line. While only one connector  36  is visible in  FIGS. 2A and 2B , it will be appreciated that the port  28  is also in fluid communication with the connector located on the opposite side of the helmet  22 , again via the helmet conduit  40 . In one embodiment, the helmet conduit  40  is at least partially embedded within an internal padded portion (not shown in  FIG. 2 ) of the helmet  22 . In other embodiments, the helmet conduit  40  may be located between the padded portion of the helmet  22  and an outer shell of the helmet. The helmet conduit  40  may be formed integrally with the helmet body  24 , for example by moulding the conduit onto or into the padded portion or the outer shell of the helmet. 
     The manifold  34  is, in one embodiment, an elongate structure formed at, or near to, a top edge of the visor  26 . In other embodiments, the manifold  34  is formed integrally with the visor  26 , and may be positioned elsewhere on the visor, for example separated from the top edge. The manifold  34  will be discussed in greater detail with reference to  FIGS. 6 and 7 . In general, however, the manifold  34  is a tubular member having an inlet  42  at each end and a plurality of outlets  44  spaced at least partially along the length of the manifold. The inlets  42  of the manifold  34  may be connected to the connectors  36  directly or via additional pipes  45 . Air can be transported into the manifold via the air inlets  42 , and can exit the manifold via air outlets  44 . Air fed through the manifold  34  is directed, via the outlets  44  onto a surface of the visor  26 . 
     Each of the inlets  42  of the manifold  34  is connected to one of the pair of connecters  36 . In one embodiment, a channel (not shown in  FIGS. 2A and 2B ) is formed in the connector  36  such that, when the visor  26  is closed, in the configuration shown in  FIG. 2A , then air is able to flow from the helmet conduit  40  to the manifold  34 , but when the visor is lifted and moved into the open configuration, shown in  FIG. 2B , the arrangement of the connectors  36  is such that the passage between the helmet conduit  40  and the manifold  34  is at least partially blocked, restricting the flow of air to the manifold. Instead of flowing through the manifold  34 , air is caused to flow through an exit aperture (not shown) in the connectors  36 . 
       FIG. 3  shows the body  24  of the helmet  22  without the visor  26  and connectors  36 . The helmet conduit  40  is shown extending from the port  28  around an inner surface of the helmet body  24  towards openings  46 ,  48  in the sides of the helmet body. The openings  46 ,  48  are shaped to receive the connectors  36  for connecting the visor  26  to the helmet body  24 . 
     From  FIG. 3 , it can be seen that the helmet conduit  40  is substantially ‘T’ or ‘Y’-shaped with an inlet portion  50  connected to the port  28 , a first arm  52  configured and positioned to connect to a first of the pair of connectors  36 , and a second arm  54  configured and positioned to connect to a second of the pair of connectors  36 . By forming the helmet conduit  40  in a fork-shape, with the first and second arms  52 ,  54 , it is possible to ensure that the pressure of air entering each of the inlets  42  of the manifold  34  is substantially equal. This serves to maintain a relatively constant air pressure along the length of the manifold  34 . 
     While, in some embodiments, the port  28  may be located on the left-hand side of the helmet body  24 , in other embodiments, the port may be located on the right-hand side of the helmet body. Alternatively, the port  28  may be located at or near to the front or back of the helmet body  24 . By locating the port  28  near to the base of the helmet body  24 , a motorcyclist  12  is able to locate the port easily and to plug the umbilical  32  into the port after mounting the motorcycle  10 . The user may, for example, use a side-mounted wing mirror on the motorcycle  10  to aid the location of the port  28  on the helmet  22 . 
       FIG. 4  shows the visor  26  with a connector  36  located near to each end of the visor. The connectors  36  may be formed integrally with the visor  26 , or fitted to the visor through apertures formed therein (not shown). The manifold  34  extends around an upper edge of the visor  26 , and is connected to the connecter  36  at each end. The structure of the connectors will be described in detail with reference to  FIG. 5 . In general, however, in this embodiment, each connector is formed of an outer part  56  that is fixedly attached to the visor  26 , and an inner part  58  that is fixedly attached in the openings  46 ,  48  in the helmet body  24 . 
     Referring now to  FIG. 5 , a sectional view of the connector  36  according to one embodiment of the invention is shown. In this embodiment, the outer part  56  and the inner part  58  of the connector  36  may be attached respectively to the visor  26  and to the helmet body  24  by a strong adhesive. The inner part  58  has a recess  60  configured to receive a complementary shaped projection  62  of the outer part  56 . When the projection  62  of the outer part  56  is pushed sufficiently far into the recess  60  of the inner part  58 , a rim  64  formed around a periphery of the inner part  58  can engage with and click into a complementary shaped channel  66  formed around a periphery of the projection  62 , thereby connecting the outer part to the inner part and, therefore, the visor  26  to the helmet body  24 . In this embodiment, the projection  62  and the recess  60  are substantially frusto-conical in shape. However, it will be appreciated that the projection  62  and the recess  60  could have any suitable complementary shapes. 
     An inner fluid channel  68  feeds into the recess  60  through a connection pipe  70 . The connection pipe  70  is arranged to connect to the helmet conduit  40  for receiving air from the umbilical  32  and the air pump  30 . 
     An outer fluid channel  72  is formed in the outer part  56  of the connector  36 , from a wall of the projection  62  to an outlet  74 . The outlet  74  can be connected to the inlet  42  of the manifold  34  directly, or via an additional pipe or tube, such as the pipe  45  (see  FIG. 4 ). The outer fluid channel  72  is shaped and positioned such that, when the outer part  56  is connected to the inner part  58 , and the visor  26  is in its closed configuration as shown in 
       FIG. 2A , the inner fluid channel  68  and the outer fluid channel  72  are in alignment, and air is able to flow from the connection pipe  70  to the outlet  74 . However, when the visor  26  is moved into its second configurations as shown in  FIG. 2B , the inner fluid channel  68  and the outer fluid channel  72  are not aligned, and the flow of air from the connection pipe  70  to the outlet  74  is restricted. 
       FIG. 6  shows the connector  36  according to another embodiment of the invention. In this embodiment, the connector  36  includes an elongate aperture  76  through which air is able to pass and an air barrier region  78 . In  FIG. 7 , the connector  36  is shown attached to the visor  26 . The manifold  34  on the visor  26  terminates with the air inlet  42  at the aperture  76  of the connector  36 . The helmet conduit  40 , shown with a dashed line, also terminates at the aperture  76  of the connector  36  such that air is able to pass from the helmet conduit, through the aperture in the connector, and via the air inlet  42  into the manifold  34 . 
     The connector  36 , as is described above, allows the visor  26  to pivot relative to the helmet body  24 . In this embodiment, the visor  26  can be pivoted through an angle of approximately 45 degrees. Thus, when the visor  26  is in its closed position, it is considered to be in an unrotated position, and the air inlet  42  of the manifold  34  is located at a first end  76   a  of the elongate aperture  76 , in line with the line marked “0deg” in  FIG. 6 . As the visor  26  is rotated clockwise (opening the visor), the air inlet  42  of the manifold  34  moves along the length of the elongate aperture  76 . Air will continue to flow from the helmet conduit  40  through the aperture  76  and into the manifold  34  until the air inlet  42  reaches a second end  76   b  of the elongate aperture  76 , which represents a rotation of approximately 30 degrees, as indicated in  FIG. 6 . As the visor  26  is opened further, the air inlet  42  of the manifold  34  is rotated beyond the end  76   b  of the elongate aperture  76 . The connector  36  forms a barrier between the helmet conduit  40  and the air inlet  42  and, consequently, air is unable to flow from the helmet conduit into the manifold  34 . Instead, air flows from the helmet conduit  40 , through the elongate aperture  76 , and through a venting aperture  80  formed in the visor  26 . When the visor  26  is opened to its full extent, its rotation relative to the helmet body  24  is approximately 45 degrees from its original, closed position. In its open position, the end of the manifold  34  engages with the air barrier region  78 . 
     The arrangement of the connector  36  in this embodiment causes air to flow from the helmet conduit  40  into the manifold  34  when the visor is in its closed position or when the visor is opened by a small amount (through a rotation of around 30 degrees), but the air flow into the manifold is restricted when the visor is fully open. 
       FIG. 8  is a sectional view through the manifold  34  and the visor  26 , along the line A-A of  FIG. 4 . The manifold  34  is formed near to a top edge of, and integrally with, the visor  26 . In other embodiments, the manifold  34  may be formed at the top edge of the visor  26 , and formed separately from and connected to (i.e. not formed integrally with) the visor. A channel  82  extends along the length of the manifold  34 , and the plurality of outlets  44  are formed in a bottom wall of the manifold. In this embodiment, a ridge  84 , or Coanda strip, is formed immediately below, and along the length of, the manifold  34 , but the ridge may be formed lower down the visor  26  such that there is a gap between the manifold and the ridge. In other embodiments, a plurality of individual protrusions might be formed below the manifold, each protrusion being located below one of the plurality of outlets  44 . As air passes through the outlet  44  towards the surface of the visor  26 , it passes over the ridge or protrusion  84 . The ridge  84  causes the air to travel in a path shown by the arrows X, due to an effect known as the Coanda effect, which causes fluid to be attracted to a surface. In this way, the air passing through the outlet or outlets  44  is less likely to flow away from the visor and, instead, is drawn towards the surface of the visor as it flows downwards. Consequently, the moisture removal effect by the air is likely to be more effective. 
     In some embodiments, instead of the plurality of outlets  44 , a single outlet may be formed in the manifold  34 , in the form of a slit, along at least part of the length of the manifold. In this way, air is able to flow out of the manifold in the form of a blade or curtain of air rather than in the form of a plurality of individual jets of air. 
       FIG. 8  shows an outlet  44  of the manifold  34  oriented such that air is able to flow out of the outlet in a direction away from the surface of the visor. As is explained above, the ridge  84  formed near to the outlet  44  causes air leaving the outlet to be drawn towards the surface of the visor due to the Coanda effect. In some embodiments, each outlet  44  is formed and/or oriented such that air is able to flow out of the outlet in a direction substantially parallel to the surface of the visor. Again, in these embodiments, the ridge  84  causes air flowing out of each outlet to be drawn towards the surface of the visor due to the Coanda effect. 
     In  FIGS. 2A, 2B and 4 , the air delivery element, or manifold,  34  is shown to be located near to the top of the visor  26 , with one or more outlets  44  positioned such that air is able to flow over the visor surface towards a bottom edge of the visor. However, as is mentioned above, the manifold  34  may be positioned elsewhere on the visor  26 .  FIGS. 9, 10 and 11  show an embodiment of the invention in which the visor  26  includes a manifold  34  which is formed at, or near to, a bottom edge of the visor. In this embodiment, air can be directed from outlets in the manifold  34  over the ridge  84  towards a top edge of the visor. 
     In this embodiment, the manifold  34  is formed of a plurality of pathways or channels. The connectors  36 , via which the visor  26  can be connected to a helmet are, in  FIGS. 9 and 11 , labelled  36   a  and  36   b . A first connector  36   a  is located on a first side  26   a  of the visor, and a second connector  36   b  is located on a second, opposite side  26   b  of the visor. A first air delivery channel  86  is in fluid communication with the first connector  36   a  such that air can flow via the first connector into the first air delivery channel. The first air delivery channel  86  terminates at an air barrier  88 , which is located substantially centrally on along the length of the visor. That is to say, the air barrier  88  is located at approximately the midway point on the visor with respect to the first connector  36   a  and the second connector  36   b . A second air delivery channel  90  is in fluid communication with the second connector  36   b  such that air can flow via the second connector into the second air delivery channel. The second air delivery channel  90  also terminates at the air barrier  88 , such that air is not able to flow between the first and second air delivery channels  86 ,  90 . 
     A first air exit channel  92  is located, in this embodiment, beneath the first air delivery channel  86 , and is in fluid communication with the first air delivery channel via a first pair of connector channels  94 . In this embodiment, air is able to flow from the first air delivery channel  86  into the first air exit channel  92  via the two connector channels  94 . However, in other embodiments, a single connector channel  94  or more than two connector channels may be provided to enable air to flow between the first air delivery channel  86  and the first air exit channel  92 . The first air exit channel  92  has closed ends  92   a  and  92   b . The closed end  92   b  is substantially aligned with the air barrier  88 , at approximately the midway point on the visor with respect to the first connector  36   a  and the second connector  36   b.    
     Similarly, a second air exit channel  96  is located, in this embodiment, beneath the second air delivery channel  90 , and is in fluid communication with the second air delivery channel via a second pair of connector channels  98 . In this embodiment, air is able to flow from the second air delivery channel  90  into the second air exit channel  96  via the two connector channels  98 . However, in other embodiments, a single connector channel  98  or more than two connector channels may be provided to enable air to flow between the second air delivery channel  86  and the second air exit channel  96 . The second air exit channel  96  has closed ends  96   a  and  96   b . The closed end  96   b  is substantially aligned with the air barrier  88 , at approximately the midway point on the visor with respect to the first connector  36   a  and the second connector  36   b . The air delivery channels  86 ,  90  are, in this embodiment, formed entirely within the visor, such that no portion of the air delivery channels protrudes from the surface of the visor. 
     In this embodiment, the connector channels  94 ,  98  are spaced apart from one another and each connector channel is spaced apart from an end of the air exit channel  92 ,  96 . Consequently, the connector channels  94 ,  96  nearest to the air barrier  88  are also spaced apart from the air barrier. This arrangement enables air to gather in a volume of the air delivery channels between the connector channel and the air barrier  88 , in a so-called “dead end” region, before it flows through the connector channels into the air exit channels  92 ,  96 . This amplifies the rate of flow of the air through the connector channels. 
     In this embodiment, the connector channels  94 ,  98  are oriented such that they are substantially perpendicular to the air delivery channels  86 ,  90  and to the air exit channels  92 ,  96 . In other words, the connector channels  94 ,  98  are configured such that air flowing through them flows in a direction substantially perpendicular to the general direction in which air is able to flow through the air delivery channels  86 ,  90  and the air exit channels  92 ,  96 . In other embodiments, the connector channels  94 ,  98  may be arranged in a different orientation. 
     Each of the air exit channels  92 ,  96  includes an outlet  44  formed substantially along its length. Each outlet  44  is in the form of a slit which is configured to direct air from the air exit channels  92 ,  96  in a direction substantially parallel to the surface of the visor  26  at the outlet. As can be seen from  FIG. 10 , the air exit channels  92 ,  96  are formed within a lip which protrudes outwards slightly from the surface of the visor  26  to enable the outlet  44  to direct the air in the desired direction (that is, parallel to the surface of the visor at the outlet). However, the air delivery channels  86 ,  90  are, in this embodiment, formed within the visor  26  itself, and do not protrude beyond the surface of the visor. 
     The arrangement of an outlet  44  being located on each side of the visor  26  provides an even distribution of air over the central portion of the visor surface, which is the area most desired to be cleared of moisture. 
     Each of the air delivery channels  86 ,  90  and the air exit channels  92 ,  96  has a substantially circular cross-section with a diameter of between around 4 mm and 6 mm and, preferably, with a diameter of approximately 5 mm. Each of the connector channels  94 ,  98  also has a substantially circular cross-section, but has a diameter which is slightly less than that of the air delivery channels  86 ,  90  and the air exit channels  92 ,  96 . For example, each of the connector channels  94 ,  98  may have a cross-sectional diameter of between around 3 mm and 5 mm, and preferably of approximately 4 mm. By forming the connector channels  86 ,  90  with a diameter which is slightly smaller than the diameter of the air delivery channels  86 ,  90  and the air exit channels  92 ,  96 , air is able to flow into the air exit channels at a greater rate, and under greater pressure, than the air flowing into the air delivery channels. 
     The first air delivery channel  86  extends from the first connector  36   a  positioned near to the first end of the visor, to the air barrier  88 . Similarly, the second air delivery channel  90  extends from the second connector  36   b  positioned near to the second end of the visor, to the air barrier  88 . However, the first air exit channel  92 , which includes the outlet or outlets  44  extends only around a front portion of the visor  26  below the first air delivery channel  86 , from the first end  92   a  to the second end  92   b  and, similarly, the second air exit channel  96  extends only around a front portion of the visor  26  below the second air delivery channel  90 , from the first end  96   a  to the second end  96   b . This arrangement enables air to be directed onto the portion of the surface of the visor which, in use, is substantially in front of the user&#39;s eyes, but air is not directed onto the side portions of surface of the visor, near to the connectors  36   a ,  36   b , where a clear visor surface is not needed. 
       FIG. 11  shows a front view of the visor  26 , with the air barrier  88  positioned so as to prevent air from flowing from the air inlet ( 42 ,  FIG. 7 ) in the first connector  36   a  (located on the left hand side of the visor as it is viewed in  FIG. 11 ) into the second air delivery channel  90  on the right hand side of the visor in  FIG. 11 . The air barrier  88  also prevents air from flowing from the air inlet ( 42 ,  FIG. 7 ) at the second connector  36   b  (located on the right hand side of the visor  26  as it is viewed in  FIG. 11 ) into the first air delivery channel  86  on the left hand side of the visor in  FIG. 11 . 
     The air barrier  88  is provided to prevent turbulence which might otherwise be caused by a collision of air flowing in the first air delivery channel  86  from the first connector  36   a  with air flowing in an opposite direction in the second air delivery channel  90  from the second connector  36   b . When air flowing through the first or second air delivery channels  86 ,  90  encounters the air barrier  88 , its flow rate through the channel is reduced dramatically, and the pressure of air in the upper channel is increased such that air flows more readily through the connector channels  94 ,  98  into the air exit channels  92 ,  96 . 
     In the embodiment shown in  FIGS. 9, 10 and 11 , the ridge  84  is formed above the air delivery channels  86 ,  90 . The ridge  84  has a substantially semi-circular cross section. As can be seen in  FIGS. 9 and 10 , the width of the ridge  84  is greatest in the centre of the visor, where the ridge has a width of around 5 mm to 11 mm, and preferably a width of approximately 8 mm. The diameter of the cross section of the ridge  84  reduces towards its ends, such that the ridge  84  tapers to a point  100  at either end. The reason for the width and height of the ridge decreasing as the ridge extends around the sides of the visor is to compensate for the difference in the shape and profile of the visor from its centre to its sides. Near to the sides of the visor, a smaller ridge  84  is capable of creating a sufficient Coanda effect in the air flowing from the outlets  44 . 
     The combination of the helmet  22 , the air pump  30  and means for delivering air from the air pump to the visor  26  of the helmet can be considered to be a moisture displacement system. 
     Various modifications to the embodiments described above will be apparent to those skilled in the relevant field. For example, in one alternative embodiment, the air pump  30  may be activated automatically. In one embodiment, the air pump  30  is switched on automatically if the speed of the motorcycle to which it is attached increases beyond a predetermined level. Similarly, the air pump  30  may be switched off automatically if the speed of the motorcycle falls below the predetermined level. 
     It will be apparent to those skilled in the art that the visor and helmet body may be constructed as separate and independent entities. A visor constructed in accordance with the present invention may be fitted to any suitable helmet body having a conduit suitable for delivering air to the manifold of the visor. Accordingly, it will be appreciated that the visor may be manufactured and marketed independently of the helmet body. Alternatively, a visor and helmet body may be marketed together as a complete helmet system. In a further alternative, the visor and helmet system may be marketed together with an air source and conduit for delivering air from the air source to the helmet. 
     So far, the invention has been described in terms of individual embodiments. However, those skilled in the art will appreciate that various embodiments of the invention, or features from one or more embodiments, may be combined as required. It will be appreciated that various modifications may be made to these embodiments without departing from the scope of the invention, which is defined by the appended claims.