Abstract
A shield includes one or more protrusion members having shapes protruding from an outer surface of the shield are provided or, alternatively, one or more recesses having shapes depressed from the outer surface of the shield are carved. The one or more protrusion members or the one or more recesses are located at vicinities of both side positions on the shield for covering a face where the lateral width of the shield in right and left directions becomes a maximum.
Claims
1. A shield, which can be rotatably connected to a helmet to cover a front window of the helmet for providing a field view to a helmet wearer, is made from a light transmitting synthetic resin and has an inner surface intended to face the helmet wearer and an outer surface, comprising: one or more protrusion members directly formed on the outer surface of the shield and each having a protruding shape protruding from the outer surface of the shield that are provided or, alternatively, one or more recesses each having a depressed shape depressed from the outer surface of the shield that are carved, from vicinities of both side positions on the shield where the lateral width of the shield in right and left directions becomes a maximum to rear ends of the shield, wherein each of the one or more protrusion members or the one or more recesses has a stream line shape which is on the outer surface of the shield, wherein the stream line shape is a round end tapering to a narrower end.
2. The shield according to claim 1, wherein the one or more protrusion members or the one or more recesses are arranged along a circumference of the shield outer periphery.
3. The shield according to claim 1, wherein each of the one or more protrusion members or the one or more recesses has a horizontally elongated shape extending in frontward and rearward directions of the shield.
4. The shield according to claim 2, wherein each of the one or more protrusion members or the one or more recesses has a horizontally elongated shape extending in frontward and rearward directions of the shield.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 is a perspective view of the entirety of a helmet installed a shield.
(2) FIG. 2 is a perspective view of the entirety of a shield.
(3) FIG. 3A is a view of a main part showing a situation that members are attached to a shield according to an embodiment of one or more embodiments of the present invention.
(4) FIG. 3B is an enlarged view of a main part showing a situation that members are attached to a shield according to an embodiment of one or more embodiments of the present invention.
(5) FIG. 4 is a diagram used for describing the rider head angle of a dummy head in a state of riding on a motorcycle.
(6) FIG. 5 is a diagram used for describing a relation between forces acting on a helmet in a situation that a running wind is received from frontward in a running state.
(7) FIG. 6A is a diagram used for describing a situation that the rider head angle is 20 degrees in a situation that a shield to which protrusion members according to an embodiment of one or more embodiments of the present invention are attached is mounted.
(8) FIG. 6B is a diagram used for describing a situation that the rider head angle is 30 degrees in a situation that a shield to which protrusion members according to an embodiment of one or more embodiments of the present invention are attached is mounted.
(9) FIG. 6C is a diagram used for describing a situation that the rider head angle is 35 degrees in a situation that a shield to which protrusion members according to an embodiment of one or more embodiments of the present invention are attached is mounted.
(10) FIG. 7 is a table showing experimental results in which a relation between the rider head angle and forces acting on a helmet in a traveling wind in a situation that a shield to which the protrusion members according to an embodiment of one or more embodiments of the present invention were attached was compared with the previous one.
(11) FIG. 8 is a graph showing experimental results of measurement of a noise reaching the ears of a wearer in a traveling wind in a situation that a shield to which the protrusion members according to an embodiment of one or more embodiments of the present invention was attached was compared with the previous one.
DESCRIPTION OF THE EMBODIMENTS
(12) In one or more embodiments of the present invention, the above-mentioned problems in the aerodynamic characteristics and the wind noise in the helmet of the previous art are resolved. That is, the protrusion members are attached to the side portions of a shield mounted on a helmet or, alternatively, the recesses are formed by carving the helmet outer surface so that the resistance force on the helmet is reduced and the noise is suppressed. Here, an embodiment of one or more embodiments of the present invention is given below for a case that the protrusion members are attached. However, even if the recesses are provided, it is obvious that a substantially similar effect is obtained.
(13) First, the overall shapes of a shield and a helmet according to the present embodiment are described below. FIG. 1 is a perspective view of the entirety of a helmet installed a shield. FIG. 2 is a perspective view of the entirety of the shield.
(14) The helmet 1 (see FIG. 1) for a motorcycle rider is installed a shield 3 (see FIG. 2) for covering a front window 2 for providing a field of view to the rider in an attachable and detachable manner. The shield 3 is made from a hard synthetic resin (such as polycarbonate) having a light transmitting property. Then, two or more protrusion members according to the present embodiment are provided in a part A which is one of portions located at the right and left side surface ends of the shield 3 having a roughly elliptic shape in FIG. 2, within the surface facing against the direction of traveling. Obviously, also in a case that the recesses are provided, the recesses are provided at similar positions.
(15) Next, the shield and the protrusion members according to the present embodiment are described below. FIG. 3 is an enlarged view of a main part showing a situation that the protrusion members are attached to the shield according to the present embodiment.
(16) As shown in FIG. 3A, two or more protrusion members 300 are provided in a periphery part 30L at the left side surface end of the shield 3. Further, although not illustrated, two or more protrusion members are provided similarly in the periphery part at the right side surface end. Here, in FIG. 4, the motorcycle is mounted a cowl.
(17) Next, the rider head position of a dummy head in a state of riding a motorcycle is described below. FIG. 6 is a diagram used for describing a situation that the rider head angle is changed in a situation that the shield to which the protrusion members according to the present embodiment are attached is mounted.
(18) As shown in FIG. 6, the inclined angle of the dummy head 4 is denoted by the angle when the rider takes a frontward-leaning posture relative to the horizontal plane on his motorcycle. As described later, the rider takes a more frontward-leaning posture with increasing the speed of the motorcycle. Thus, the rider head angle increases with increasing the speed of the motorcycle.
(19) Next, the cowling (the cowl) provided in the motorcycle is described below. FIG. 4 is a diagram showing a situation that the motorcycle is mounted the cowl.
(20) As shown in FIG. 4, the cowling (the cowl) 6 indicates the entirety consisting of a windshield part 6A provided in a front upper part of the motorcycle and a body cover part 6B on the vehicle body front side of the motorcycle 5. When the cowling (the cowl) 6 is mounted, it can avoid a traveling wind directly hits the rider.
(21) Next, a relation between forces acting on the helmet is described when a traveling wind is received from frontward during the running. FIG. 5 is a diagram used for describing a relation between the forces acting on the helmet when a traveling wind is received from frontward in a running state.
(22) As shown in FIG. 5, three forces are generated by the wind pressure on the helmet 1 of the rider during the riding. A first is a drag force which is a force of pulling the helmet 1 immediately rearward. A second is a lift force which is a force of pulling the helmet 1 immediately upward. A third is a yaw force which is a force of pulling the helmet 1 immediately sideward. The helmeted dummy doll simulating the rider in traveling was experimented with changing the rider head angle . And the drag force, the lift force, and the yaw force acting on the dummy head were measured in order to review the differences between the helmet 1 mounted the shield 3 with the members according to the present embodiment and one mounted the conventional shield.
(23) FIG. 7 is a table showing the experimental results in which the shield with the members according to the present embodiment was compared with the conventional shield about the forces acting on the helmet in traveling wind at each rider head angle. In those experiments, each eight protrusion members having a stream line shape were provided on the both side surface ends of the shield in a manner that each tip of the stream line was oriented rearward. Further, in the experiments, three rider head positions were set up at a wind speed of 160 km/h. Then, 3,000 measurement data logs per approximately 300 seconds were acquired and then the average was calculated as the measured value.
(24) As for the rider head angle , experiments were performed for three angle values consisting of =20 degrees shown in FIG. 6A, =30 degrees shown in FIG. 6B, and =35 degrees shown in FIG. 6C selected from actual riding postures. FIG. 6 is a diagram used for describing a situation that the rider head angle was changed with the shield which the protrusion members according to the present embodiment were provided. Here, the entire present experiments were performed in a situation that the cowling (the cowl) 6 was provided.
(25) As seen from the results of the experiments shown in FIG. 7, at the rider head angle of 20 degrees, the drag force has decreased by 9%, the lift force has decreased by 4%, and the yaw force has decreased by 10%. Further, at the rider head angle of 30 degrees, the drag force has decreased by 6%, the lift force has decreased by 2%, and the yaw force has decreased by 32%.
(26) FIG. 8 is a graph showing the results of measurement of a noise reaching the ears of the helmet wearer when a traveling wind was received. The solid line indicates the results of the helmet provided with the shield which had the members according to the present embodiment. The dashed line indicates the results of the conventional one. The horizontal axis of the graph indicates the sound frequency and the vertical axis indicates the sound pressure level. As seen from the results of the experiments, at almost all frequencies, the helmet provided with the shield which had the members according to the present embodiment had a lower sound pressure level than the conventional one.
(27) Here, the experiments shown in FIGS. 7 and 8 were performed in a situation that eight protrusion members attached to both the right and left side surface ends of the shield. However, an arbitrary number of protrusion members may be attached to the shield.
(28) Further, also as for the orientation of each protrusion member, the orientation need not be substantially in parallel to the helmet bottom part. Further, the intervals between the protrusion members need not be regular. These conditions may be set up arbitrarily in accordance with an intention which air flow is to be separated from which position. That is, after observed the flow of air on the helmet side surfaces, the number, the positions, and the interval of the protrusion members may be designed such as to be most effective.
(29) Further, the embodiment given above has been described for a shield of a motorcycle helmet serving as a typical article. However, one or more embodiments of the present invention can be applied also to an article other than a shield of a motorcycle helmet.
(30) The present invention can give a shield and a helmet which can suppress the noise and the air resistance, because of reducing a noise generated close to the ears an air resistance acting on the helmet which are caused by the wind swirled along the helmet surface from lower side to upper side owing to a wind flowing at the helmet bottom part, that is, from the throat to the neck of the helmet wearer.
(31) The present invention has been described above with reference to preferred embodiments of one or more embodiments of the present invention. Although the present invention has been described with reference to particular and specific examples, various modifications and changes may be made on these specific examples without departing from a wide variety of the spirit and the scope of the present invention set forth in the claims.
