Vehicle fuel supply device and fuel filter structure

Invention Patent Report for MOTORCYCLES EQUIPPED WITH AN ENGINE ABLE TO OPERATE WITH VARIOUS DIFFERENT TYPES OF FUELS. DESCRIPTION

TECHNICAL AREA [001] The present invention relates to an improvement in fuel supply devices for vehicles, as well as an improvement in fuel filter structures, which contains a fuel filter made of non-woven material. BACKGROUND OF THE TECHNIQUE [002] Among the fuel filling devices for vehicles, known conventionally, are those that include a fuel filter inside a fuel tank (for example, International Publication WO2004 / 072469). In the vehicle fueling device described in Patent Literature 1, the fuel filter is arranged, substantially centrally at the bottom of the fuel tank, a fuel pump unit is arranged at the rear of the fuel tank and the filter The fuel pump and fuel pump unit are interconnected by means of a fuel pipe.

[003] In cases where fuel, such as ethanol, is used with fine dust, the fuel filter must have a filtration mesh or small pore size (ie, fineness of filtration); but in these cases the fuel filter has to be replaced in a short cycle, which increases the number of times that maintenance service must be performed. Furthermore, when that small pore fuel filter is provided upstream of the fuel pump unit and when a quantity of fuel to be filled has increased rapidly, for example, when the vehicle is accelerating, it is difficult for a necessary quantity of

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2/33 fuel is filled, because the fuel filter becomes a resistance to the fuel stream, so there is a need to increase the capacity or performance of the fuel pump unit, which requires higher costs.

[004] In addition, fuel supply devices have been known, in which a filter housing and a pressure regulator are provided in one piece with each other (for example, Japanese Patent Application Publication of Exhibition No. 0874710 ( JP-08-74710 A). In the fuel supply device described in Patent Literature 2, a fuel filter includes: a housing with an inlet, an outlet and a recirculation port; a filter insert with a cylindrical shape, disposed inside the housing; and a pressure regulator, disposed inside the housing, adjacent to the recirculation port. The filter insert has opposite end caps, installed in the housing and supported by a support tube. The pressure regulator is disposed inside the filter insert, and the fuel is filtered as it passes through the filter insert from the outside to the inside of the filter insert.

[005] If an attempt is made to ensure a large surface area of ​​the filter insert for greater filtration capacity, the housing must be larger in size. In addition, as the filter insert requires the support tube to act as a frame, and end caps, the fueling device requires a large number of component parts and, therefore, requires high costs. In addition, the pressure regulator inside the housing is subject to spatial limitation, due to the provision of the filter insert and the support tube, which results in an extremely limited freedom of disposal of the pressure regulator,

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3/33 fuel suction etc. In addition, if the pressure regulator is placed near the recirculation door, a location for installing the recirculation door will be limited.

[006] In addition, fuel filter structures have been known, which contain a filter element made of nonwoven or similar material (for example, Japanese Patent Application Publication of Exhibition No. 2003-148267 (JP 2003-148267 A) . In the fuel supply device described in JP 2003148267 A, a filter cartridge includes a bag-shaped filter element, formed of a mesh, non-woven material or the like, and an assembly section, provided in a part with the bag-shaped filter element. The connection port, provided in the assembly section, is connected to a suction port of a fuel pump. The bag-shaped filter element is attached to the mounting section by means of a suction port member inserted into the element. The suction port member has, in one piece, a frame member, to retain the bag-shaped filter element in an inflated shape.

[007] In cases where a primary fuel filter, with a small pore size, is used in a fuel system, such as that described in JP 2003-14827 A, to filter fuel, such as ethanol fuel , with fine dust (particles), an obstruction can easily occur in the primary fuel filter. If the primary fuel filter's surface area is increased in order to extend the life of the primary fuel filter, the primary fuel filter will increase in size, resulting in limited freedom of disposal and higher costs. In addition, as the aforementioned filter cartridge includes the suction port member, the mounting section and the frame member, in addition to the

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4/33 bag, the cartridge would have to be a large total size. With vehicles, such as motorcycles, in which there is considerable limitation in relation to the available disposal space in the vehicle body, it is desirable to build the fuel supply system in a compact size, using a filter made of non-woven material , which achieves high filtration efficiency, even with a small surface area.

DESCRIPTION OF THE INVENTION [008] In view of the foregoing, it is an objective of the present invention to provide a fuel supply device for vehicles, which is inexpensive, obtains a prolonged cycle of changing or replacing a fuel filter and can supply constantly amount of fuel needed.

[009] It is another objective of the present invention to provide an improved fuel supply device, equipped with a fuel filter, which is compact in size and requires only a small number of component parts and which can increase freedom of provision of a pressure regulator, fuel suction port, etc.

[0010] It is yet another objective of the present invention to provide an improved fuel filter structure, which allows a long life of a fuel filter, and which obtains a reduced size of the fuel filter, housing the filter compactly in a housing .

[0011] In accordance with an aspect of the present invention, an improved vehicle fueling device is provided, comprising: a fuel pump, for supplying fuel from a fuel tank to an injector, which releases the fuel towards an engine; a filter

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5/33 primary fuel, arranged in a fuel passage upstream of the fuel pump; and a secondary fuel filter, arranged in the fuel passage downstream of the fuel pump. The secondary fuel filter has a smaller filtration mesh or pore size than the primary fuel filter, and the secondary fuel filter is covered with a housing member and arranged along a vehicle body frame.

[0012] In conventionally known fuel supply devices, in which only one fuel filter is provided, both large (particulate) powder and fine (particulate) powder are collected by the same filter, so that the fuel filter it tends to clog easily and so the fuel filter change or replacement cycle would be very short. In addition, a quantity of fuel that passes through the fuel filter tends to become small. In the fuel supply device of the present invention, on the other hand, the pore size of the secondary fuel filter is smaller than that of the primary fuel filter; in this way, large (particle) dust is collected by the primary fuel filter, and then finer (particle) powder, which has passed through the primary fuel filter, is collected by the secondary fuel filter. Since this arrangement according to the invention effectively prevents the secondary fuel filter from collecting large dust, the secondary fuel filter may be less susceptible to clogging, and thus a frequency of replacing the secondary fuel filter can be reduced. In addition, the primary fuel filter may also be less susceptible to clogging, due to its large pore size, and thus can be prevented from becoming a resistance to the fuel stream in the fuel pump.

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6/33 fuel.

[0013] Consequently a high current flow of the fuel that passes through the primary fuel filter and secondary fuel filter can be safely maintained over a long period of time. Therefore, a very cheap fuel pump can be used in the fuel supply device of the invention. As a result, the present invention can achieve longer replacement or replacement cycles of both the primary fuel filter and the secondary fuel filter, so that the number of times that maintenance work must be carried out can be reduced. In addition, a high current flow rate of the fuel passing through the primary fuel filter and the secondary fuel filter can be maintained over a long period of time, and thus the present invention can properly handle situations where the flow rate of fuel current increases rapidly.

[0014] Preferably, secondary fuel filter is arranged at the rear of the engine. With such an arrangement, the fuel supply device of the invention can make the second fuel filter less subject to engine heat, as compared to conventionally known fuel supply devices, where the fuel filter is arranged above the engine.

[0015] Preferably, the secondary fuel filter is disposed laterally outside the body frame. In this way, maintenance work, such as replacing the secondary fuel filter, can be easily performed on one side of the vehicle.

[0016] Preferably, the secondary fuel filter is connected to the body frame by means of a support and the body frame has an inwardly hollow part, formed in one position

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7/33 corresponding to an internal surface of the secondary fuel filter. In this way, when an external lateral force acts on the secondary fuel filter, for example, the support is curved towards the inside of the vehicle body, and the secondary fuel filter moves into the concave part into the frame. the body of the vehicle; in this way, a movable amount of the secondary fuel filter can be increased, and the increased movable amount allows an external force, acting on the secondary fuel filter, to be absorbed with increasing ease.

[0017] Preferably, the secondary fuel filter is covered on an external side surface with an external member. In this way, the external side surface is not exposed to the outside, so that an enhanced external appearance of the vehicle can be obtained.

[0018] Preferably, a fuel supply pipe is connected to a downstream side of the secondary fuel filter and extends upwards to a throttle body located above the secondary fuel filter. In this way, air inside the secondary fuel filter can easily flow into the throttle body fuel injection valve through the fuel supply pipe. This arrangement allows for a uniform supply of fuel through the fuel passage, including the secondary fuel filter.

[0019] Preferably, the supply device has a fuel return port provided in an upper part of the housing member, and a fuel return tube, arranged to extend upwards from the fuel return port to the tank of fuel. Thus, if air is mixed in the fuel line of the fuel pump, air can easily be

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8/33 driven out of the fuel line.

[0020] In accordance with another aspect of the present invention, an improved fuel supply device is provided, comprising: a fuel filter, disposed outside a fuel tank; and a filter housing, which covers an external surface of the fuel filter; and a pressure regulator, provided in one piece with the filter housing to regulate a pressure inside the fuel filter, with the fuel that passed through the pressure regulator being returned to the fuel tank. The fuel filter is formed in a pocket format, and the fuel is filtered by passing through the fuel filter from the inside to the outside of the fuel filter.

[0021] As the fuel filter is bag-shaped, the filter can be compactly housed in the filter housing and the housing can be formed in a reduced size. In addition, as the fuel filter body is inflated and stably maintained in the inflated format when fuel is passed through the bag-shaped fuel filter from the inside to the outside, no special frame member is required for the fuel filter. fuel. As a consequence, the present invention can reduce the number of necessary component parts of the fuel filter.

[0022] Furthermore, as the fuel filter to be housed within the housing can be easily changed in shape as needed, the present invention can increase the freedom of disposal of the pressure regulator and fuel return port, provided close to the pressure regulator.

[0023] Preferably, the fuel filter is arranged downstream of a fuel pump, and the pressure regulator is arranged downstream of the fuel filter. In this way, the fuel that has passed through the fuel filter body is resent to

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9/33 the fuel tank, through the pressure regulator, with most of the dust removed or filtered from the fuel. Consequently, in the case of another filter, for example, a primary fuel filter, being provided inside the fuel pump, an amount of dust to be filtered through the primary fuel filter can be reduced significantly. As a result, the present invention can achieve a longer cycle of changing or replacing the primary fuel filter, so that the number of times that maintenance work must be carried out can be reduced.

[0024] Preferably, the fuel supply device also comprises a fuel return pipe, arranged to extend upwards from the pressure regulator to the fuel tank, located above the pressure regulator. In this way, air accumulated inside the fuel filter can easily escape through the pressure regulator to the fuel tank, located above the fuel filter. As a result, the present invention makes it possible for the fuel supply through the fuel passage to be carried out uniformly.

[0025] Preferably, the fuel supply device further comprises a fuel supply pipe for supplying fuel from the fuel tank to the fuel filter, and the fuel supply pipe and the fuel return pipe differ each other in length and outside diameter.

[0026] Because the fuel supply pipe and the fuel return pipe have different lengths and outside diameters or widths, this fuel supply pipe and the fuel return pipe are easily

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10/33 distinguishable. In this way, the present invention can prevent an assembly error in the assembly of the fuel supply pipe and the fuel return pipe in the fuel filter.

[0027] Preferably, the filter housing includes a housing body and a housing cover. The fuel suction port and the fuel return port are arranged offset from the central axis of the housing cover; thus, if the pressure regulator is arranged close to the fuel return port, the present invention can increase the freedom of layout and shape of the pressure regulator, which can make the filter housing compact in size.

[0028] Preferably, the filter housing has a stepped part, which protrudes radially out of the filter housing, and the pressure regulator has a lower end supported on the stepped part. In this way, the present invention can simplify the structure to support the pressure regulator, with the result that the increased costs of the filter housing and the fuel filter can be minimized.

[0029] In accordance with yet another aspect of the present invention, an improved fuel filter structure is provided, comprising a primary fuel filter, arranged upstream of a fuel pump, and a secondary fuel filter, arranged downstream. of the fuel pump and made of a non-woven material, with a pore size smaller than a pore size of the primary fuel filter.

[0030] On the condition that the secondary fuel filter made of non-woven material has a smaller pore size than the primary fuel filter, the primary fuel filter may have a larger pore size, and the life of the filter Primary fuel can be extended even further. As the primary fuel filter

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11/33 is planned upstream of the fuel pump, the life of the fuel pump can also be extended if the primary fuel filter is set to a relatively large pore size such that it does not adversely affect the fuel pump. In addition, because the secondary fuel filter is made of non-woven material, the effective filtration area can be increased and, thus, the filtration efficiency can be increased to a significant degree. In addition, the secondary fuel filter can have a reduced surface area, so the secondary fuel filter can be built in a compact size. In addition, since fuel filtration is performed in cooperation by the primary fuel filter and secondary fuel filter, the present invention can significantly extend the life of the secondary fuel filter, compared to the case, where only one of these fuel filters fuel is provided.

[0031] In accordance with yet another aspect of the present invention, an improved fuel filter structure is provided, comprising: an enclosure; and a filter made of non-woven material, the filter being housed in the wrapper in a rolled or folded form. With the filter compactly housed in the housing in a rolled or folded configuration, with a reduced total size, the housing and therefore the fuel filter may be smaller in size.

[0032] Preferably, it has a bag format and the filter filters the fuel passing through it, from the inside of the filter to the outside of the filter. As the fuel is supplied to the bag-shaped filter, the filter inflates, so that the filter contained in the filter flows through the filter to the outside, due to the increase of internal pressure inside the filter, during which dust

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12/33 mixed in the fuel is removed or filtered from the fuel. As the filter is inflated and kept in the inflated shape, no special frame member is needed to maintain the inflated shape; thus, the present invention can reduce the cost required for the fuel filter and can even reduce the size of the filter further.

[0033] Preferably, a door for the filter is connected to the inner surface of the filter, rolled or folded in an outward orientation. In this way, no projected part is formed on the external wall of the rolled or cylindrically folded part of the filter, which allows a reduction in the size of the housing. In addition, since the internal space of the housing can be used efficiently in the manner mentioned above, the filter body can have a larger area.

[0034] Preferably, the housing has a plurality of convex parts, which project into the internal surface, and the filter is supported, in part, by the convex parts. In this way, when the fuel flows into the filter, intermediate spaces between the inflated filter and the inner surface of the housing can be guaranteed by the convex parts, and the fuel is allowed to flow through the filter into the intermediate spaces. Consequently, the present invention can suppress a decrease in the flow of the fuel stream, or stagnation of the fuel and, thus, can increase the efficiency of the fuel filtration.

BRIEF DESCRIPTION OF THE DRAWINGS [0035] Certain preferred embodiments of the present invention are described in detail below, by way of example only, with reference to the accompanying drawings, in which:

[0036] Figure 1 is a side view of a vehicle, which is

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13/33 equipped with a fuel filtration device according to an embodiment of the present invention;

[0037] Figure 2 is a side view, showing the main sections of the fueling device according to the embodiment of the invention;

[0038] Figure 3 is a perspective view, showing the main sections of the fueling device according to the embodiment of the invention;

[0039] Figure 4 is a sectional view of a fuel pump used in the fueling device according to the embodiment of the invention;

[0040] Figures 5A and 5B are, in each case, the side and perspective view, which illustrate a secondary fuel filter and the mounting structure for it in the embodiment of the invention;

[0041] Figures 6A and 6B are plan views, showing the general functioning of the assembly structure for the secondary fuel filter;

[0042] Figure 7 is a sectional view of the secondary fuel filter;

[0043] Figures 8A and 8B are, in each case, a perspective view and an exploded fragmented view of the secondary fuel filter;

[0044] Figures 9A and 9B are explanatory views of a filter element used in the present invention, of which figure 9A is a sectional view, taken along line 9-9 of figure 8B, and figure 9B is a view in perspective, showing the filter element housed in a filter housing; and [0045] Figures 10A and 10B are a cross-sectional view of the secondary fuel filter according to the present embodiment of the invention.

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14/33

BEST MODE FOR CARRYING OUT THE INVENTION [0046] Initially, reference is made to figure 1, which shows in side projection a vehicle equipped with a fuel filtration device and a fuel filter structure according to an embodiment of the present invention. Vehicle 10 is a motorcycle, which includes an engine 12, arranged substantially centrally on a vehicle body frame 11, a front fork 13, drivably supported on a front end portion of the vehicle body frame 11, and a fork rear 14, held vertically rotatable on a lower rear part of the vehicle body frame 11. Vehicle 10 uses as its main fuel ethanol, gasoline or a mixture of gasoline and ethanol, and uses as its secondary fuel, gasoline or a mixture of gasoline and ethanol (with a higher gasoline to ethanol mixture ratio than in fuel main), only when the engine starts, for example, when the engine start is not uniform, too, due to a low temperature.

[0047] The vehicle body frame 11 is a structure formed by the joining of a plurality of pressure molded parts and includes a front tube 21, provided at its front end, a main frame 22, which extends behind the front tube 21, a central frame 23, extending downwardly from an intermediate part of the main frame 22, a secondary frame 24, coupled to a rear part of the main frame 22 and a lower part of the central frame 23, and a descending frame 26, which extends behind and below the front tube 21.

[0048] The front tube 21 has a front fork 13 rotatably mounted on it, and a handlebar 31 and a front (road) wheel 32 are connected, in each case, to the top and bottom of the front fork 13 The main fuel tank 33,

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15/33 for storing the main fuel, it is mounted on and through a front part of the main frame 22 and a seat 34 is mounted at the rear of the main frame 22. The secondary fuel tank, for storing the secondary fuel, is arranged inside the main fuel tank 33.

[0049] The central frame 23 supports the motor 12, together with the descending frame 26. The rotary axis 36 supported by the central frame 23 serves as an axis that allows the vertical rotation of the rear fork 14. The rear (road) wheel 35 is attached to the rear end of the rear fork 14.

[0050] The rear shock absorber unit 37 is connected to and extends between respective rear parts of the rear fork 14 and main frame 22. The descending frame 26 supports the motor 12 by means of a support 38.

[0051] The transmission 41 is provided in one piece with a rear part of the engine 12 and a cylinder head 44 is mounted to a cylinder section 43, which extends upwards, of the engine 12. An air intake device 46 it is connected to a rear part of the cylinder head 44, and a discharge device 47 is connected to a front part of the cylinder head 44.

[0052] The air inlet device 46 includes an inlet tube connected at one end to the cylinder head 44, a throttle body 52, connected at one end to the other end of the inlet tube 51, and an air filter air 54, connected to the other end of the throttle body 52 by means of a connection tube 53.

[0053] The exhaust device 47 includes an exhaust pipe 56, connected at one end to a front part of the cylinder head 44 and extending down and behind the front part of the engine 12, and a muffler 57, connected to the other end of the exhaust pipe 56 and extending backwards.

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16/33 [0054] In the figure, reference number 61 designates a front hood, 62, a headlight, 63, a front fender, 64, a side cover, which folds the sides of the air filter 54, 66 , a rear side cover, 67, a rear fender, 68, a rear headlight, 71, a main bracket, 72 a transmission output shaft 41, 73, a drive sprocket, connected to the output shaft 72 , 74, a driven sprocket, joined in a fur on the rear wheel 35, 76, a chain, which extends between and is wound on its opposite sides on the drive sprocket and on the driven sprocket 73 and 74, and 77, a chain cover.

[0055] Figure 2 is a side view, showing main sections of the fueling device according to the embodiment of the invention. The primary fuel filter 141 for filtering the main fuel (hereinafter simply called fuel) is disposed within a fuel pump 92, which in turn is connected to a bottom 91 of the main fuel tank 33, and a secondary fuel filter 143 to further filter the fuel, is connected to the fuel pump 92 by means of a fuel supply pipe

142 made of resin. The fuel supply pipe 144 is connected at one end to the secondary fuel filter

143 and extends upwards, to be connected at its other end to a fuel injector (injector) 94, which is arranged in the throttle body 52, located above the secondary fuel filter 143; that is, the fuel injection valve 94 is connected to the secondary fuel filter 143 by means of the pipe 144. The secondary fuel filter 143 is located downstream of the primary fuel filter 141, disposed within the fuel pump 92. As will be described later with reference to figure 3, the fuel distribution line (not shown in figure 2)

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17/33 extends from the secondary fuel filter 143 to the main fuel tank 33.

[0056] The left side (that is, the side visible in figure 2) of the secondary fuel filter 143 is covered with the side cover 64 (see figure 1) and therefore is not exposed to the outside, so it can an enhanced external appearance of the vehicle can be obtained.

[0057] The secondary fuel filter 143 has a filtration mesh or pore size smaller than that of the primary fuel filter 141; for example, the pore size of the secondary fuel filter 143 is 30 pm, while the pore size of the primary fuel filter 141 is 70 pm. In this way, the primary fuel filter 141 collects relatively large dust (particles) and the secondary fuel filter 143 can collect finer dust (particles) that passes through the primary fuel filter 141. How this arrangement prevents the fuel filter secondary 143 to collect relatively large dust, secondary fuel filter 143 may be less subject to clogging. In addition, primary fuel filter 141 may also be less subject to clogging, due to its large pore size.

Consequently, the present modality can obtain longer cycles of exchange or replacement, both of primary fuel filter 141 and secondary fuel filter 143, so that the number of times that maintenance work needs to be carried out can be reduced. In addition, a high current flow rate of the fuel passing through the primary fuel filter 141 and secondary fuel filter 143 can be maintained for a long period of time. As a result, the present modality can deal appropriately with situations, where the flow of fuel current increases rapidly, when the vehicle is started, accelerated or similar.

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18/33 [0059] In addition, as the secondary fuel filter 143 is arranged at the rear of the engine 12, the input device 46 (more specifically, the throttle body 52) and the secondary fuel filter 143 can be positioned close to each other. In this way, the present embodiment can shorten the length of the fuel supply pipe 144, which is connected between the secondary fuel filter 143 and the fuel injector valve 94 of the throttle body 52, so that the installation of the fuel pipe needed can be significantly facilitated.

[0060] Figure 3 is a perspective view, showing the main sections of the fueling device according to the embodiment of the invention. The secondary fuel filter 143 is disposed laterally outside the central frame 23 and fixedly connected to the central frame 23 by means of a support 146. The fuel return pipe 135 extends above the secondary fuel filter 143, to be connected to the main fuel tank 33.

[0061] The fuel return pipe 135 is, for example, in the form of a rubber hose, which is smaller in length and larger in external diameter or width than the fuel supply pipe 142, made of resin, and thus, it is easily distinguishable from the fuel supply pipe 142; therefore, it is possible to avoid an assembly error in the assembly of the fuel supply pipe 142 and the fuel return pipe 135 in the secondary fuel filter 143.

[0062] The fuel supply pipe 144 is arranged to extend from the downstream side of the secondary fuel filter 143 upwards, to the throttle body 52 (more specifically, to the fuel injector valve 94 of the throttle body 52),

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19/33 located above the secondary fuel filter 143. In this way, air inside the secondary fuel filter 143 easily leaves the filter 143 and flows into the fuel injection valve 94 of the throttle body 52 through the fuel supply pipe 144; this arrangement allows for a uniform supply of fuel through a fuel passage, including the secondary fuel filter 143.

[0063] The structural components described above arranged in a region of the main fuel tank 33 for the fuel injector valve 94, that is, the main fuel tank 33, primary fuel filter 141 (see figure 2), fuel pump 92, fuel supply pipe 142, secondary fuel filter, fuel return pipe 135, fuel supply pipe 144, throttle body 52 and fuel injector valve 94, together, they constitute the fuel supply device 150 of the invention.

[0064] By arranging the secondary fuel filter 143 laterally outside the central frame 23, as noted above, maintenance work, such as replacing the secondary fuel filter 143, can be easily performed on one side of the vehicle. In addition, it is possible to increase the capacity of the secondary fuel filter 143, so that an undesirable pulse of the fuel can be less easily decreased.

[0065] Figure 4 is a sectional view of the fuel pump used in the fuel supply device 150. The fuel pump 92 includes a lower casing 151 made of resin, fixedly attached to the main fuel tank 33 (see figure 2) , an upper housing 152, made of metal or resin, fixedly connected to an upper part of the lower housing 151, and a drive section 153, disposed within the upper housing 151 and the

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20/33 lower housing 152.

[0066] The lower housing 151 includes a flange part 155 for connection to the main fuel tank 33, a fuel passage 156 through which the fuel fed to the drive section 153 runs, and a discharge port 157, connected to the fuel pass 156. The primary fuel filter 141 is housed in the lower storage compartment 151.

[0067] The upper housing 152 has a plurality of suction ports 161 formed therein, for aspirating the fuel. The drive section 153 includes a motor, and a pump driven by the motor. The primary fuel filter is arranged upstream of drive section 153 of fuel pump 92.

[0068] As indicated by arrows in the figure, the fuel is sucked through the suction ports 161 of the upper housing 152 and passes through the primary fuel filter 141, after which the fuel rises in the drive section 153 and passes through the fuel passage 156 to the discharge port 157. Then, through the discharge port 157, the fuel flows into the fuel supply pipe 142 of figure 2 and then reaches the secondary fuel filter 143, shown in figure 2.

[0069] Figures 5A and 5B are, in each case, side and perspective views, which explain the secondary fuel filter 143 and the mounting structure for it in the present modality.

[0070] As shown in figure 5A, support 146, which has a plate and metal shape, is attached to the central frame 23, and the secondary fuel filter 143 is supported by support 146.

[0071] The secondary fuel filter 143 includes a shell (member) 171 made of resin, and a filter body 181 (shown in figure 7) made of non-woven material and housed within the shell 171. The shell 171 includes a 173 tubular housing body, and a cap

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21/33 of housing 174, which closes an upper door of housing body 173.

[0072] The housing body 173 has a fuel discharge port 171b provided in its bottom part. The casing lid 174 has a fuel suction port 171a on top and a fuel return port 171c to resend fuel to the main fuel tank 33 (see figure 2).

[0073] As shown in figure 5B, the central frame 23 includes a side part 23a, which extends in one direction (i.e., left-right) towards the vehicle, a longitudinal part 23b, which extends in one direction towards the front of the vehicle, from one end of the side part 23a, a curved part 23c, which extends in directions forward and into the vehicle, and a front part 23d, which extends in the direction forward of the vehicle , from the front end of the curved part 23c. The support 146 is fixed on the longitudinal part 23b, and the secondary fuel filter 143 is fixed on the support 146.

[0074] By forming the central frame 23 in a curved configuration, as noted above, it is possible to increase the stiffness, particularly flexural stiffness, of the central frame 23 in the front-rear and width of the vehicle.

[0075] If an imaginary straight line 165 is drawn along the longitudinal part 23b, as illustrated in figure 5B, the secondary fuel filter 143 is located laterally outside the straight line 165 and, therefore, from the central frame 23. The central frame 23 has in its part an external lateral surface, corresponding in position to the internal surface of the secondary fuel filter 143, a stepped part 23f, as a concave part in the direction towards the vehicle body, which is constituted by the curved part

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22/33

23c above and front 23d.

[0076] Figures 6A and 6B are plan views, showing the general functioning of the assembly structure for the secondary fuel filter 143.

[0077] In figure 6A, the support 146 includes a rear flat plate part 146a, welded to the longitudinal part 23b of the central frame 23, a curved part 146b, which is curved laterally outwardly from the front end of the flat plate part rear 146a, and a front flat plate portion 146c, which extends towards the front of the vehicle, from the front end of the curved portion 146b. The front flat plate portion 146c is connected to a housing body 173 of the secondary fuel filter 143, extending through a portion of housing body 173.

[0078] For example, when an external force acts on the secondary fuel filter 143 on one side, as indicated by a white arrow, the external force is transmitted to the support 146 through the secondary fuel filter 143, so that the curved part 146b and the part located in front of the curved part 146 are curved towards the central frame 23, as shown in figure 6B. At that time, the secondary fuel filter 143 moves into the stepped or concave part into 23f of the central frame 23.

[0079] With the concave part 23f, formed in the central frame 23, in order to allow the secondary fuel filter to move into the concave part 23f when an external force acts on the secondary fuel filter 143, a movable amount of the secondary fuel filter 143 can be increased, and the increased movable amount allows an external force acting on the secondary fuel filter to be absorbed with increasing ease.

[0080] Figure 7 is a sectional view of the fuel filter

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23/33 secondary 143, used in the present embodiment of the invention. Secondary fuel filter 143 includes housing 171, with housing body 173 and housing cover 174, which closes the upper door of housing body 173, as noted above, and a filter element 176 housed within the housing 171. The housing body 173 has the fuel suction port 171, for aspirating fuel, and the fuel return port 171c, for resending fuel to the main fuel tank 33 (see figure 3). Housing cap 174 has fuel discharge port 171b for discharging fuel.

[0081] Filter element 176 includes bag-shaped filter body 181, made of non-woven material, and a connection port 182, which communicates with the interior of filter body 181 and is connected to the fuel suction 171a from housing cap 174.

[0082] Secondary fuel filter 143 also includes a pressure regulator 186, arranged in a piece with the bottom surface of the casing cap 174 and, when a fuel pressure within secondary fuel filter 143 has exceeded a predetermined value, that pressure regulator 186 operates to return fuel to the main fuel tank 33, thereby regulating the fuel pressure within the secondary fuel filter 143. In addition, a non-return valve 188 is disposed within the fuel discharge port 171b of the housing body 173.

[0083] The pressure regulator 186 includes a cylinder bottom regulator housing 191, made of resin, installed in a cylindrical part 174a, formed in one piece with the bottom surface of the housing cover 174, a spherical valve member, made steel, to open / close a through hole 191a, formed at the bottom

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24/33 of the regulator housing 191, and a spiral compression spring 193, to normally force valve member 192 to close through hole 191a. The through hole 191a communicates with the interior of the filter element 176, and an upper port 191b of the regulator housing 191 communicates with the interior of the fuel return port 171c.

The regulator housing 191 has its lower end surface 191A supported on a stepped portion 173, connected between a small diameter pipe part 173A and a large diameter pipe part 173B of the housing body 173.

[0085] Reference number 174 indicates an annular fitting part, which is formed in one piece with the bottom surface of the housing cover 174 and fits in an upper part of the housing body 173, and 195 indicates an O-ring , which forms a seal between the tubular part 174a and the regulator housing 191.

[0086] The check valve 188 includes a valve housing

196, a valve body 197 arranged for vertical movement within valve housing 196, and a spring 198, to normally compress a semi-spherical head portion 197a of valve body 197 against a tapered valve seat 196a. In the figure, valve body 197 closes tapered valve seat 196a.

[0087] The fuel inside the shell 171 is allowed to flow from inside the secondary fuel filter 143 to the outside (that is, to the fuel injection valve 94 (see figure 3)), through the fuel discharge port 171b, pushing down the valve body 197 against the elastic compression force of the spring 198. Backflow of fuel from fuel injector valve 94 to secondary fuel filter 143 can be prevented by rising valve body 197 so that head part 197a leans against valve seat 196a to close the passage

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25/33 fuel.

[0088] During the operation of the engine 12, the fuel pump operates in such a way that the pressure of the fuel pump 92 pushes the valve body 197 downwards, against the elastic compression force of the spring 198, thereby causing that the fuel flows to the fuel injector valve 94 (see figure 2), through the fuel discharge port 171b and the fuel supply pipe 144, so that the fuel injection valve 94 pushes the fuel towards the engine.

[0089] When engine 12 is deactivated, the fuel pump is deactivated, so that valve body 197 is pushed upward by spring 198 to lean against valve seat 196a, thereby closing the fuel passageway . In this way, the fuel passage extending from the fuel discharge port 171b to the fuel injector valve 94 is maintained at a high pressure.

[0090] After the shutdown of fuel pump 92, it is desirable to maintain the internal pressure in the fuel line at a high level line, in order to ensure that the fuel passage works properly, immediately after the fuel pump 92 is activated next time. But, even if the internal pressure in the fuel line is kept at a high level, the internal pressure gradually decreases by a minimum amount of fuel leaking from the pressure regulator 186 to the discharge side. That is why the check valve 188 is arranged on the discharge side of the pressure regulator 186.

[0091] Figures 8A and 8B are, in each case, seen in perspective and fragmented, in explosion, of the secondary fuel filter 143.

[0092] In the housing body 173, the tube part of diameter

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26/33 large 173B is formed continuously with the upper part of the small diameter pipe part 173A, by means of the stepped connection part 173C. The pressure regulator 186 shown in figure 7 is disposed within the large diameter pipe part 173B. The internal passage 171d, which communicates with the fuel suction port 171a, is arranged in one piece with the housing cover 174. The filter element 176 has the bag-shaped filter body 181 made of non-woven material, a fuel passage 182a, which communicates with the interior of the bag-shaped filter body 181, and the connection port 182 mentioned above, connected in the internal passage 171d of the housing cover 174. The connection port 182 is arranged in a substantially central position within the width of the filter body 181.

[0093] Figures 9A and 9B are explanatory views of the filter element 176 used in the present embodiment of the invention, of which figure 9A is a sectional view taken along line 9 - 9 of figure 8B and figure 9B is a perspective view showing the filter element 181 when housed in the filter housing 171.

[0094] In figure 9A, the filter body 181 of the filter element 176 is in the form of a bag, formed by superimposing a mesh 181B made of resin (for example, polypropylene (PP)) on a non-woven material 181A of three layers, made of resin (for example, polypropylene (PP)), then folding the overlapping mesh 181 and the material 181A in half, such that the nonwoven material 181A is positioned within the mesh 181B and then welds the respective edge parts on opposite sides of the mesh 181B and the material 181A. The filter body 181 is connected to an end part of the connection port 182 in such a way that it is fitted between an external flange 182b, which is molded in one piece with the connection port 182 and extends through the wall thickness of the body

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27/33 of filter 181, and an internal flange 182c, which is located inside the filter body 181 and adhered to the external flange 182 by ultrasonic welding, adhesive or the like, or joined to the external flange 182 by fitting by fitting with the latter.

[0095] Figure 9B shows filter body 181 rolled or folded cylindrically, with connection port 182 positioned inside body 181 when filter element 176 is to be placed in housing 171 (see figure 8B). Depending on the size of the filter body 181, the filter body 181 can be rolled up once or twice to be placed in the filter housing 171.

[0096] By placing the filter body 181 rolled or folded in this way in a housing 171, the filter body 181 can be compactly housed in the housing 171, and thus the housing 171 can be formed in a reduced size. That is, a reduction in size of the secondary fuel filter 143 can be obtained.

[0097] In figure 9B, connection port 182 is connected to and retained on an inner wall 181a of the cylindrically rolled or folded filter cup 181 and extends upwards through the upper port of the cylindrical filter body 181, in a outward orientation. Therefore, no protruding part is formed in an external wall 181b of the cylindrically rolled or folded part of the filter body 181, which allows a reduction in the size of the filter housing 171. In addition, since the internal space of the housing 171 can be used efficiently in the manner mentioned above, the filter body 181 can have an increased area.

[0098] As the pressure regulator 186 is disposed downstream of the filter body 181, the fuel, which has been filtered through the filter body 181 of the secondary fuel filter 143, is returned to the main fuel tank 33 (see figure 3 ), through the

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28/33 pressure regulator 186. Therefore, dust contained in the fuel can be refilled and passed through the primary fuel filter (see figure 2), so that the clogging of primary fuel filter 141 can be avoided more safely. Consequently, the replacement cycle of primary fuel filter 141 can be extended, which allows for improved maintenance of the fuel supply device.

[0099] In addition, as pressure regulator 186 is formed in one piece with housing 171 of secondary fuel filter 143, the present modality can significantly reduce the number of necessary component parts and, therefore, the cost of the filling device of fuel.

[00100] Furthermore, with the bottom end surface 191A of the regulator housing 191 resting on the stepped portion 173C of the housing body 173, the regulator housing 191 can be fitted between the stepped portion 173C and the housing cover 174 and, thus, properly attached to the housing 171, only by connecting the housing cover 174 to the housing body 171, after equipping the regulator housing 191 with the tubular part 174a of the housing cover 174. In this way, the present embodiment can simplify the structure for mounting pressure regulator 186 in housing 171.

[00101] Furthermore, as the secondary fuel filter 143 is disposed downstream of the fuel pump 92 and the pressure regulator 186 is disposed downstream of the filter body 181, as described above, the fuel that has passed through the body filter 181 is returned to the main fuel tank 33 (see figure 2) via pressure regulator 186, with most of the dust removed or filtered from the fuel. Therefore, in the case of another filter, that is, primary fuel filter 141, it is disposed within the

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29/33 fuel pump 92, the primary fuel filter replacement cycle 141 can be extended, so that the present mode can reduce the number of times that maintenance work needs to be carried out.

[00102] In addition, with the fuel return pipe 135, which extends upwards from the pressure regulator 186 to the main fuel tank 33, as shown in figure 3, air accumulated inside the secondary fuel filter 143 can easily run into the main fuel tank 33, located above the secondary fuel filter, and, thus, fuel supply through the fuel passage can be carried out uniformly.

[00103] Furthermore, housing 171 is comprised of housing body 173 and housing cover 174, and fuel suction port 171a and fuel return port 171c are arranged offset from a central axis 200 of the housing cover 174, as shown in figure 7. Thus, in the case where the pressure regulator 186 is arranged close to the fuel return port 171c, as shown illustratively in figure 7, it is possible to improve the freedom of layout and shape of the pressure regulator 186, and, Thus, housing 171 can be made compact in size.

[00104] Furthermore, as housing 171 has the stepped portion 173C, which protrudes radially outwardly and the lower end of pressure regulator 186, i.e. the surface of the lower end 191A of regulator housing 191, is supported on the staggered part 173C, the structure for supporting pressure regulator 186 can be simplified, so that the present embodiment can avoid a substantial cost increase of housing 171 and, therefore, secondary fuel filter 143.

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30/33 [00105] Figures 10A and 10B are a cross-sectional view of the secondary fuel filter according to the present embodiment of the invention.

[00106] Figure 10A shows a state, in which no fuel has been supplied to the filter body 181 of the secondary fuel filter 143, and in which the bag-shaped filter body 181 is left rolled up and not inflated. In the figure, the reference number 173a indicates the inner surface of the housing body 173 and the reference number 173b indicates a plurality of convex parts 173b, protruding into the inner surface 173a of the housing body 173.

[00107] Figure 10B shows a state, in which fuel was supplied via the connection port 182 of the secondary fuel filter 143 to the filter body 181, and in which the filter body 181 was inflated, due to an increase internal fuel pressure. In this state, the fuel that is filled gradually flows from the connection port 182 towards the discharge end, as indicated by arrows, while the fuel passes through the filter body 181, from the inside to the outside of the body 181. At that moment, a plurality of intermediate spaces 201 is formed, by the plurality of inward convex parts 173b, between the inflated filter body 181 and the inner surface 173a of the housing body 173, and the fuel flows into the intermediate spaces 201, of so that it runs to other regions through the intermediate spaces 201. In this way, the present modality can prevent undesirable fuel stagnation, thereby obtaining improved fuel filtration efficiency.

[00108] Furthermore, in the fuel supply device 150, as shown in figures 2, 7 and 10A and 10B, the secondary fuel filter 143 is disposed outside the fuel tank

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31/33 fuel 33, the outside of the secondary fuel filter 143 is covered with the filter housing 171, and the pressure regulator 186, for regulating the pressure inside the secondary fuel filter 143 is provided in one piece with the fuel housing filter 171, so that the fuel that has passed pressure regulator 186 is returned to the fuel tank 33. In addition, secondary fuel filter 143 is bag-shaped, and fuel is filtered through secondary fuel filter 143 as it passes through filter body 181, from inside to outside filter body 181. Therefore, the Filter body 181 can be compactly housed in housing 171 and thus housing 171 can be formed in a reduced size.

[00109] Furthermore, as the filter body 181 is inflated and stably maintained in the inflated format when fuel is passed through the filter body 181, from the inside to the outside of the filter body 181, no special frame is required for the filter member 181. Therefore, the present embodiment can reduce the number of necessary component parts of the filter body 181. [00110] Furthermore, as the filter body 181 to be housed within the housing 171 can be easily changed in shape, when necessary, the present modality can increase the freedom of disposal of the pressure regulator 186 and the fuel return port 171c.

[00111] It is observed that, although the present modality has been described above in relation to the case, in which the pressure regulator 186 is provided in a part with the cover of the housing 174 of the housing 171, as shown in figure 7, the present invention is not limited to that; for example, the pressure regulator 186 may be provided in the housing body 173.

[00112] In addition, as described above, the filter body 181

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32/33 is formed in a bag format, the fuel is filtered when the fuel passes from the inside to the outside of the bag, and the 181B mesh, which is less subject to deformation, bending and similar than the non-woven material 181A , is arranged outside the non-woven material 181A. In this way, the filter body 181 can maintain its inflated shape when fuel is supplied to the bag-shaped filter body 181. Therefore, no special frame is required for the filter body 181 and, therefore, the present embodiment can achieve a substantial reduction in the cost of the secondary fuel filter 143. In addition, the secondary fuel filter 143 can be built in a even smaller size.

[00113] Furthermore, the filter body 181 is supported, in part, by the convex parts 173b, which protrude into the inner surface 173a. Thus, when the fuel flows into the filter body 181, the plurality of intermediate spaces 201 between the inflated filter body 181 and the inner surface 173a of the housing body 173, and the fuel within the fuel filter can be ensured. secondary 143 is allowed to flow into the intermediate spaces 201 through the filter body 181. Consequently, the present modality can suppress a decrease in the flow of the fuel stream, or stagnation of the fuel and, thus, can increase the fuel filtration efficiency.

[00114] Furthermore, as the primary fuel filter 141 is arranged upstream of the fuel pump 92 (more specifically, upstream of the drive section 153), as seen from figures 2, 4 and 5, and the secondary fuel 143 made of non-woven material with a smaller pore size than the primary fuel filter 141 is disposed downstream of the fuel pump

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33/33 fuel 92, primary fuel filter 141 may have a larger pore size. In this way, the present embodiment can extend not only the life of the primary fuel filter 141, but also the life of the fuel pump 92, arranged downstream of the primary fuel filter 141.

[00115] Furthermore, with the secondary fuel filter 143, made of non-woven material, the fuel filtration efficiency can be increased to a significant level, and the secondary fuel filter 143 can have a reduced surface area, so that secondary fuel filter 143 can be built in a compact size. In addition, as the fuel filtration is carried out in cooperation with the primary fuel filter 141 and the secondary fuel filter 143, the present modality can significantly extend the life of the secondary fuel filter 143, compared to the case, where only one of these fuel filters is planned.

[00116] Although the present embodiment has been described above in relation to the case, where the bag body filter 181 is positioned inside the housing 171 in a rolled or folded form, the present invention is not limited in this way. For example, the filter body 181 can be positioned inside the housing 171 in a folded shape. In that case, the shape of the shell 171 is not limited to a tubular or cylindrical shape, as indicated above, and the shell 171 can be of any other desired shape, such as a cube, parallelepiped or square pyramid.

INDUSTRIAL APPLICABILITY [00117] The fuel supply device and fuel filter structure described above of the present invention are particularly suitable for application to motorcycles.