JP2008163755A - Straddle type vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the deterioration of the performance of a low pressure pump and a pipe injection injector when an engine provided with the pipe injection injector and a cylinder injection injector is applied to a straddle type vehicle such as a motorcycle. <P>SOLUTION: The motorcycle is provided with the cylinder injection injector injecting fuel into a combustion chamber and the pipe injection injector injecting fuel into an intake air passage. A branch pipe 130 is provided at the downstream end of a first low pressure fuel pipe 124 leading fuel fed from a low pressure pump in a fuel tank. A delivery pipe 118 supplying fuel to the pipe injection injector is connected to the branch pipe 130 via a second low pressure fuel pipe 125. The branch pipe 130 and a high pressure pump 123 are connected via a third low pressure fuel pipe 126. The third low pressure fuel pipe 126 includes a flexible U-turn part 126f and is elongated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a straddle-type vehicle such as a motorcycle.

  2. Description of the Related Art Conventionally, as an engine for a four-wheeled vehicle, an engine that performs fuel injection using an in-pipe injector that injects fuel into an intake pipe and an in-cylinder injector that directly injects fuel into a combustion chamber has been proposed. (For example, refer to Patent Document 1). According to this engine, it is possible to improve engine output, improve fuel efficiency, and the like as compared with an engine having only a pipe injection injector.

  Incidentally, the in-cylinder injector must inject fuel at a very high pressure against the pressure in the combustion chamber. Therefore, the engine includes a high-pressure pump in addition to the low-pressure pump that pumps fuel from the fuel tank. The fuel pumped from the low pressure pump is diverted, one fuel is supplied to the in-pipe injector, and the other fuel is supplied to the high pressure pump. The fuel supplied to the high pressure pump is pressurized by the high pressure pump and supplied to the in-cylinder injector.

In order to enable such fuel supply, the fuel pipe on the discharge side of the low-pressure pump (low-pressure fuel pipe) branches in the middle, one of the pipes after the branch is connected to the in-pipe injector, and the other pipe is the high-pressure pump Connected to the suction side. As described above, in the engine including the in-cylinder injector and the in-pipe injector, the configuration of the fuel pipe is complicated.
JP 2005-155421 A

  By the way, compared to a four-wheeled vehicle, a saddle-type vehicle such as a motorcycle has a problem that the installation space for vehicle parts is greatly limited. Therefore, when an engine including the above-described in-cylinder injector and in-pipe injector is applied to a motorcycle or the like, the following problems occur. That is, in the motorcycle, the above-described low-pressure fuel pipe arrangement position is limited to, for example, a narrow region between the pair of left and right main frames on the lower side of the fuel tank. Therefore, the area where the low-pressure fuel pipe can be arranged is small, and therefore the length of the low-pressure fuel pipe is shortened.

  Here, since the motorcycle includes the low pressure pump and the high pressure pump, fuel pressure pulsation occurs in the low pressure fuel pipe due to the operation of the high pressure pump. Therefore, if the low-pressure fuel pipe is short as described above, the pulsation of the fuel pressure is transmitted to the low-pressure pump and the in-pipe injection injector, which may lead to a decrease in performance of the low-pressure pump and the in-pipe injection injector.

  In particular, depending on the type of engine such as a motorcycle, constant pressure control is performed to return a part of the fuel in the pump chamber of the high-pressure pump to the low-pressure fuel pipe side in order to keep the fuel pressure acting on the in-cylinder injector constant. May be. Therefore, particularly in this type of engine, fuel pressure pulsation is likely to occur in the low-pressure fuel pipe due to the return of fuel from the high-pressure pump.

  Further, depending on the type of motorcycle, there is a type in which a fuel tank is attached to the vehicle body frame so as to rotate with a front end portion as a fulcrum. That is, the fuel tank can be easily attached and detached by releasing the fixation of the rear end portion of the fuel tank and turning the front end portion etc. as a fulcrum. In this type of motorcycle, when a work is performed on a vehicle part or the like below the fuel tank, the fuel tank is often rotated so as to be in an upright state so as not to get in the way. By the way, the low-pressure pump is usually arranged in a fuel tank. Therefore, if the low-pressure fuel pipe is short as described above, the low-pressure pump moves together when the fuel tank is rotated. As a result, the low-pressure fuel pipe can be extended only by moving the fuel tank a little. Therefore, before the fuel tank is rotated, the low-pressure fuel pipe must be removed from the low-pressure pump, and complicated work is required.

  The present invention has been made in view of such a point, and one of its purposes is when an engine including an in-cylinder injector and an in-pipe injector is applied to a straddle-type vehicle such as a motorcycle. It is suppressing that the performance of a low pressure pump or a pipe injection injector falls. Another object of the present invention is to improve the convenience in attaching and detaching the fuel tank.

  A straddle-type vehicle according to the present invention includes an engine body having a combustion chamber and an intake passage that guides air to the combustion chamber, an in-cylinder injector that injects fuel into the combustion chamber, and fuel into the intake passage. An in-pipe injector that injects fuel, a fuel tank that stores fuel, a low-pressure pump that is provided in the fuel tank and conveys the fuel in the fuel tank, and a first low-pressure fuel that guides the fuel conveyed by the low-pressure pump A pipe, a branch pipe that diverts the fuel guided by the first low-pressure fuel pipe, and a second low-pressure fuel pipe that is connected to the branch pipe and guides one fuel after the diversion toward the in-pipe injector. A third low-pressure fuel pipe that is connected to the branch pipe and guides the other fuel after the diversion, and a fuel guided by the third low-pressure fuel pipe to pressurize the in-cylinder injection injector Comprising a high-pressure pump for conveying towards the motor, and at least one of the first low-pressure fuel pipe and the third low-pressure fuel pipe are those provided with a U-turn portion having flexibility.

  According to the straddle-type vehicle, the first low-pressure fuel pipe positioned between the low-pressure pump and the branch pipe and / or the third low-pressure fuel pipe positioned between the branch pipe and the high-pressure pump are flexible. The U-turn part which has property is provided. Therefore, the first and / or third low-pressure fuel pipe can be lengthened.

  By lengthening the low-pressure fuel pipe in this manner, fuel pressure pulsation in the low-pressure fuel pipe can be sufficiently suppressed. As a result, transmission of fuel pressure pulsation to the low-pressure pump can be suppressed, and performance degradation of the low-pressure pump can be prevented.

  Further, according to the saddle riding type vehicle, the fuel tank can be moved greatly when the fuel tank is removed. Therefore, it is not necessary to remove the low-pressure fuel pipe from the low-pressure pump when removing the fuel tank. Further, since it is not necessary to remove the low-pressure fuel pipe from the low-pressure pump, it is not necessary to connect the low-pressure fuel pipe to the low-pressure pump when the fuel tank is attached to the vehicle body. As a result, the convenience in attaching / detaching the fuel tank is improved.

  According to the present invention, it is possible to suppress the transmission of fuel pressure pulsation, and it is possible to suppress a decrease in performance of the low-pressure pump. Moreover, the convenience at the time of attachment or detachment of a fuel tank can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the vehicle according to this embodiment is a motorcycle 10. The motorcycle 10 includes a body frame 11 that forms a skeleton, and a seat 16 on which an occupant sits. An occupant seated on the seat 16 rides over the body frame 11. In the present invention, the shape of the vehicle is not limited to the so-called motorcycle type motorcycle 10 shown in FIG. 1, but may be another type of motorcycle. Further, the maximum speed and displacement of the vehicle, the size of the vehicle, etc. are not limited. Moreover, it is not limited to a motorcycle, but may be another straddle-type vehicle such as a four-wheel buggy.

  In the following description, the front-rear and left-right directions refer to directions seen from the occupant seated on the seat 16. The vehicle body frame 11 includes a steering head pipe 12, a pair of left and right main frames 13 extending obliquely downward and rearward from the steering head pipe 12, and a pair of left and right seat rails 14 extending obliquely rearward and upward from the middle part of both main frames 13. It has.

  A front wheel 19 is supported on the steering head pipe 12 via a front fork 18. A fuel tank 20 and a seat 16 are supported on the seat rail 14. The seat 16 extends from the rear of the fuel tank 20 toward the rear end of the seat rail 14.

  A pair of left and right rear arm brackets 24 are provided at the rear end of the main frame 13. The rear arm bracket 24 protrudes downward from the rear end portion of the main frame 13. These rear arm brackets 24 are provided with a pivot shaft 38, and a front end portion of the rear arm 25 is swingably supported by the pivot shaft 38. A rear wheel 26 is supported at the rear end portion of the rear arm 25.

  The body frame 11 supports an engine unit 28 that drives the rear wheel 26. The crankcase 35 of the engine unit 28 is supported while being suspended from the main frame 13.

  The engine 29 is an in-line four-cylinder engine and is mounted in a horizontally placed state in which a crankshaft (not shown) is horizontally arranged in the vehicle width direction. The engine 29 is disposed obliquely so that an axis 41L of the cylinder 41 (indicated by a one-dot chain line in FIG. 1) tilts forward.

  FIG. 2 is an enlarged side view showing the vicinity of the engine unit 28, and FIG. 3 is an enlarged cross-sectional view showing the vicinity of the cylinder head 40 in the engine unit 28. As shown in FIGS. 2 and 3, the cylinder head 40 of the engine 29 is fixed by bolts 101 with the upper and lower surfaces of two cylinder blocks (not shown) aligned. A cylinder head cover 50 is provided so as to cover the upper surface of the cylinder head 40. The cylinder head 40 and the cylinder head cover 50 are fixed.

  A plurality (four in this embodiment, only one is shown in FIG. 5) of combustion chambers 83 is formed inside the cylinder head 40, and an intake valve 88 (see FIG. 5) and an exhaust valve 98 are formed. A valve operating mechanism including an intake side camshaft 70 and an exhaust side camshaft 80 is provided. As shown in FIG. 3, the engine 29 is an overhead camshaft type (OHC type) engine in which an intake side camshaft 70 and an exhaust side camshaft 80 are provided above a cylinder 41.

  A pump cam 123b is attached to the intake camshaft 70 described above. The pump cam 123b drives a high-pressure pump 123 (see FIG. 6) described later.

  As shown in FIGS. 3 and 4, the high-pressure pump 123 is disposed substantially at the center in the width direction of the engine 29, and a part of the upper portion is disposed between the main frames 13 (see FIG. 2). The high pressure pump 123 is fixed to the cylinder head cover 50. Specifically, a mounting flange 123g formed on the high-pressure pump 123 and a boss portion 51 formed on the cylinder head cover 50 are fastened together by a bolt 133.

  FIG. 5 is a cross-sectional view showing the peripheral structure of the cylinder 41 in the engine 29. FIG. 5 shows one of the four cylinders 41 and the structure inside and around the cylinder 41. A piston 82 is accommodated in the cylinder 41 of the engine 29 so as to be able to reciprocate. A combustion chamber 83 is formed by the upper surface of the piston 82 and the inner wall surfaces of the cylinder 41 and the cylinder head 40.

  An intake pipe 85 and an exhaust pipe 86 are connected to the cylinder 41. The intake pipe 85 communicates with the combustion chamber 83 via the intake port 87. The intake pipe 85 is provided with a throttle valve 46 that adjusts the amount of air flowing into the intake pipe 85. Note that the intake pipe 85 and the intake port 87 form an intake passage for introducing air into the combustion chamber 83. The intake port 87 is provided with an intake valve 88 that changes the communication state between the intake pipe 85 and the combustion chamber 83 by being opened and closed. The intake valve 88 is driven by an intake camshaft 70 (see FIG. 3).

  The intake pipe 85 is provided with an in-pipe injector 89 that supplies fuel into the intake pipe 85. The cylinder head 40 is provided with an in-cylinder injector 189 that supplies fuel into the combustion chamber 83. Thus, the motorcycle 10 includes two types of injectors, the in-pipe injector 89 and the in-cylinder injector 189.

  The exhaust pipe 86 is connected to the combustion chamber 83 via the exhaust port 97. The exhaust port 97 is provided with an exhaust valve 98 that changes the communication state between the exhaust pipe 86 and the combustion chamber 83 by being opened and closed. The exhaust valve 98 is driven by an exhaust side camshaft 80 (see FIG. 3). In addition, an ignition plug 99 for igniting an air-fuel mixture formed by fuel and air is disposed at the upper portion of the combustion chamber 83.

  As described above, the engine 29 includes the engine body 29a having the combustion chamber 83, the intake passage (the intake pipe 85, the intake port 87), and the injectors 89, 189, and the like.

  FIG. 6 is a diagram showing the configuration of the fuel system of the motorcycle 10. As shown in FIG. 6, a low pressure pump 122 is provided in the fuel tank 20. The low pressure pump 122 sucks the fuel in the fuel tank 20 and pumps the sucked fuel to the first low pressure fuel pipe 124. The fuel flowing through the first low-pressure fuel pipe 124 is supplied to the second low-pressure fuel pipe 125 and the third low-pressure fuel pipe 126 through the branch pipe 130 connected to the first low-pressure fuel pipe 124.

  The second low-pressure fuel pipe 125 is connected to an in-pipe injector 89 (see also FIG. 5) via a delivery pipe 118. The delivery pipe 118 stores fuel therein and supplies the fuel to the in-pipe injectors 89 corresponding to the four cylinders 41.

  A high-pressure pump 123 (see also FIGS. 2 and 3) is connected to the third low-pressure fuel pipe 126. The high pressure pump 123 further pressurizes the fuel pumped by the low pressure pump 122 and supplies the pressurized fuel toward the in-cylinder injector 189. In addition, a low-pressure side pressure accumulating chamber 107 is provided in the middle of the third low-pressure fuel pipe 126. Specifically, the low-pressure side accumulator 107 is disposed between the pipe 126a and the pipe 126b. The low-pressure side accumulator 107 is a hollow body and can store fuel therein.

  The high-pressure pump 123 includes a pump chamber 123a filled with fuel, a plunger 123c that reciprocates up and down, and an electromagnetic valve 123d that adjusts the amount of fuel supplied to the pump chamber 123a.

  The pump chamber 123a is filled with fuel pumped from the low pressure pump 122. The plunger 123c is driven by the pump cam 123b to reciprocate up and down in the pump chamber 123a. The pump cam 123b is attached to an intake side camshaft 70 (see FIG. 3), and the intake side camshaft 70 is connected to a crankshaft (not shown) via a drive chain (not shown). . Therefore, the rotation of the pump cam 123b is synchronized with the rotation of the engine 29 (the rotation of the crankshaft).

  The electromagnetic valve 123d is configured by a solenoid. The electromagnetic valve 123d includes a spill valve 123e for opening and closing a portion serving as a fuel inlet. Further, a check valve 123f is provided at a connection portion with the high-pressure fuel pipe 127 in the pump chamber 123a. The check valve 123f opens when the fuel pressure in the pump chamber 123a exceeds a predetermined value.

  The solenoid valve 123d is controlled to open and close by a control signal from an ECU (not shown). When the solenoid valve 123d is not energized, the spill valve 123e is pushed down so that the fuel tank 20 and the pump chamber 123a communicate with each other. Further, when the solenoid valve 123d is energized, the spill valve 123e is pulled up so that the fuel tank 20 and the pump chamber 123a do not communicate with each other. In FIG. 6, the spill valve 123e is shown in an open state.

  The plunger 123c described above is driven by the pump cam 123b to reciprocate within the pump chamber 123a, whereby the fuel in the pump chamber 123a is pressurized to a high pressure. When the fuel pressure in the pump chamber 123a exceeds a predetermined value, the check valve 123f is opened, so that the fuel in the pump chamber 123a is supplied into the delivery pipe 128 via the high-pressure fuel pipe 127. The high-pressure fuel supplied to the delivery pipe 128 is injected from the in-cylinder injector 189. Since the engine 29 according to the present embodiment is a four-cylinder engine, it includes four in-cylinder injectors 189 as shown in FIG.

  A high-pressure side accumulator chamber 117 is provided in the middle of the high-pressure fuel pipe 127. The high-pressure side accumulator chamber 117 is a hollow body and can store fuel therein.

  More specifically, the high-pressure pump 123 is connected to the in-cylinder injector 189 via the pipe 127a, the high-pressure side accumulator 117, the pipe 127b, and the delivery pipe 128. The delivery pipe 128 stores fuel therein and supplies the fuel to the in-cylinder injector 189 corresponding to each of the four cylinders 41.

  Thus, in the present embodiment, the high-pressure side pressure accumulation chamber 117 is provided separately from the delivery pipe 128. Therefore, the fuel pumped by the high pressure pump 123 is temporarily stored in the high pressure side pressure accumulating chamber 117 and the delivery pipe 128. Thereby, even if it is a case where the volume of the delivery pipe 128 will become small on the relationship of an arrangement position or arrangement space, the volume in which fuel is stored can be secured sufficiently large. As a result, fluctuations in fuel pressure due to fuel injection from the in-cylinder injector 189 can be reduced.

  By the way, the above-described high-pressure pump 123 keeps the fuel pressure in the delivery pipe 128 constant, and when the fuel pressure in the pump chamber 123a exceeds a predetermined value, a part of the fuel in the pump chamber 123a is supplied to the third low-pressure fuel pipe. The constant pressure control to return to the 126 side is performed. At this time, the returned fuel is supplied to the delivery pipe 118 through the third low-pressure fuel pipe 126 and the second low-pressure fuel pipe 125, so that fuel pressure pulsation easily occurs in the delivery pipe 118. . However, in the present embodiment, since the low-pressure side accumulator chamber 107 is provided between the high-pressure pump 123 and the delivery pipe 118, even when the fuel is returned from the high-pressure pump 123, this low-pressure side The pressure accumulation chamber 107 can absorb the pulsation of the fuel pressure. As a result, fuel pressure pulsation in the delivery pipe 118 can be suppressed. Further, it is possible to prevent the pulsation accompanying the fuel return control from being transmitted to the low pressure pump 122 and adversely affecting the performance of the low pressure pump 122.

  FIG. 7 is a plan view showing the arrangement of devices and members constituting the fuel system shown in FIG. FIG. 8 is a side view of FIG. As shown in FIGS. 7 and 8, the cylinder head cover 50 is disposed between the pair of left and right main frames 13 and below the main frame 13. The left and right end portions of the cylinder head cover 50 are arranged directly below the main frame 13.

  As described above, the high-pressure pump 123 is fixed to the upper surface of the cylinder head cover 50 and substantially at the center in the longitudinal direction (width direction) of the cylinder head cover 50. As shown in FIG. 7, on the upper surface of the cylinder head cover 50 and on the left and right sides of the high-pressure pump 123, ignition plugs 99 corresponding to the four cylinders 41 (see FIGS. 2 and 3) protrude upward. It is provided as follows. Of the four ignition plugs 99, two are provided on the left side of the high pressure pump 123, and the remaining two are provided on the right side of the high pressure pump 123. The four ignition plugs 99 are arranged at equal intervals along the longitudinal direction (width direction) of the cylinder head cover 50.

  The first low-pressure fuel pipe 124 connected to the fuel tank 20 (see FIGS. 1 and 6) extends forward (upward in FIG. 7) and is bent to the left in the middle to be connected to the branch pipe 130. The branch pipe 130 divides the fuel passing through the first low-pressure fuel pipe 124 into the second low-pressure fuel pipe 125 and the pipe 126 a of the third low-pressure fuel pipe 126. The second low-pressure fuel pipe 125 connected to the branch pipe 130 extends forward and is connected to the delivery pipe 118. The delivery pipe 118 is arranged such that its longitudinal direction is along the longitudinal direction (width direction) of the cylinder head cover 50.

  Further, the pipe 126a connected to the branch pipe 130 extends in the left direction, and is folded back from the vicinity of the left main frame 13 to extend in the right direction. A U-turn portion 126f is composed of a portion 126c extending in the left direction in the pipe 126a, a folded portion 126d toward the rear, and a portion 126e extending in the right direction. Since the U-turn portion 126f forms a reciprocating path, hereinafter, the portion 126c extending in the left direction is referred to as an outward path, and the portion 126e extending in the right direction is referred to as a return path.

  The right end portion of the return path 126e of the U-turn portion 126f of the third low-pressure fuel pipe 126 is connected to the low-pressure side pressure accumulation chamber 107. The low pressure side pressure accumulation chamber 107 is connected to the pipe 126b. The pipe 126b extends in the right direction, bends forward in the middle, and is connected to the high-pressure pump 123. In the present embodiment, the first low-pressure fuel pipe 124, the second low-pressure fuel pipe 125, the third low-pressure fuel pipe 126, the pipe 126a and the pipe 126b are all made of resin hoses and have flexibility. . On the other hand, the branch pipe 130 is a metal pipe.

  As shown in FIG. 8, the fuel tank 20 has a horizontal portion 20a disposed in the front-rear direction (left-right direction in FIG. 8), and a drooping portion 20b hanging downward from the rear end portion of the horizontal portion 20a. ing. A relatively wide area A is formed between the horizontal portion 20a, the hanging portion 20b, and the engine 29. In this region A, the first to third low-pressure fuel pipes 124, 125, 126, the low-pressure side accumulator 107, and the like are arranged.

  The drooping portion 20b of the fuel tank 20 has an outer surface 20c that extends downward or obliquely downward. The low-pressure side pressure accumulation chamber 107 is formed in a substantially rectangular parallelepiped shape, and is disposed so as to be substantially parallel to the outer surface 20c. By adopting such an arrangement, the low pressure side pressure accumulation chamber 107 can be enlarged to some extent, and a large internal volume of the low pressure side pressure accumulation chamber 107 can be secured. In the present embodiment, the low-pressure side accumulator 107 may be fixed to the engine 29 or may not be fixed.

  As shown in FIG. 7, the pipe 127 a connected to the high-pressure pump 123 extends rightward along the longitudinal direction (width direction) of the cylinder head cover 50. The high-pressure side accumulator chamber 117 connected to the right end portion of the pipe 127 a is disposed at the right end portion of the upper surface of the cylinder head cover 50 and is fixed to the cylinder head cover 50. Specifically, a boss portion 52 is formed at the right end portion of the upper surface of the cylinder head cover 50. On the other hand, the high pressure side accumulator chamber 117 is formed with a mounting flange 117a in which a screw hole is formed. The mounting flange 117a and the boss portion 52 are fastened together by a bolt 134, so that the high pressure side pressure accumulating chamber 117 and the cylinder head cover 50 are fixed.

  Although the cylinder head cover 50 is elongated in the vehicle width direction, camshafts 70 and 80 (see FIG. 3) and a crankshaft (not shown) are provided below the right end portion where the high-pressure side accumulator chamber 117 is disposed. Is provided with a cam chain 90 (see FIG. 8). That is, the high pressure side accumulator chamber 117 is disposed on the upper surface of the cylinder head cover 50 and above the cam chain 90.

  As described above, the high-pressure pump 123 is fixed to the upper surface of the cylinder head cover 50 at the approximate center in the longitudinal direction (width direction). Further, four ignition plugs 99 are arranged on the upper surface of the cylinder head cover 50 so as to protrude upward along the longitudinal direction. For this reason, as the arrangement position of the high-pressure side accumulator chamber 117, the longitudinal end of the cylinder head cover 50 (particularly the upper position of the cam chain 90) is desirable.

  The high-pressure fuel pipe 127b connected to the high-pressure side pressure accumulating chamber 117 extends downward toward the rear and is connected to the delivery pipe 128 (see FIG. 6).

  As described above, according to the motorcycle 10 according to the present embodiment, the third low-pressure fuel pipe 126 includes the flexible U-turn portion 126f (see FIG. 7). Therefore, the length of the third low-pressure fuel pipe 126 can be increased while keeping the installation space small. Therefore, even if a pulsation of fuel pressure occurs in the third low-pressure fuel pipe 126 due to the operation of the high-pressure pump 123, the degree of the pulsation can be suppressed. As a result, the performance degradation of the low pressure pump 122 and the in-pipe injector 89 can be suppressed.

  In the present embodiment, the U-turn part 126f is provided only in the third low-pressure fuel pipe 126, but the U-turn part 126f may be provided in the first low-pressure fuel pipe 124. Even in that case, it is possible to suppress the performance degradation of the low-pressure pump 122 caused by the pulsation of the fuel pressure. However, in this embodiment, in particular, the U-turn portion 126f is provided in the third low-pressure fuel pipe 126 that is the low-pressure fuel pipe after branching. Therefore, it is possible to effectively suppress the performance degradation of both the low pressure pump 122 and the in-pipe injector 89.

  As shown in FIG. 7, in this embodiment, the U-turn portion 126 f of the low-pressure fuel pipe 126 is disposed between the pair of left and right main frames 13. Accordingly, it is possible to suppress the performance degradation of the low-pressure pump 122 and the in-pipe injector 89 while the low-pressure fuel pipe 126 is installed in a narrow space between both the main frames 13. That is, it is possible to suppress the performance of the low-pressure pump 122 and the in-pipe injector 89 while reducing the size of the motorcycle 10.

  As shown in FIG. 8, according to the present embodiment, the high-pressure pump 123 is fixed to the cylinder head cover 50, and the cylinder 41 of the engine 29 is tilted forward. As a result, a certain amount of space is formed between the low pressure pump 122 and the high pressure pump 123. The U-turn portion 126 f of the low-pressure fuel pipe 126 is disposed between the low-pressure pump 122 and the high-pressure pump 123. Therefore, the above space can be effectively used as an installation space for the U-turn portion 126f, and the low-pressure fuel pipe 126 can be arranged in a compact manner.

  As shown in FIG. 7, according to the present embodiment, the U-turn portion 126f is formed so as to have an outward path 126c and a return path 126e that extend in the vehicle width direction and are adjacent to each other in the front-rear direction in plan view. Yes. The forward path 126c and the return path 126e are formed so as to be adjacent to each other in the vertical direction when viewed from the front (FIG. 8 is a side view, but see FIG. 8). Thus, the U-turn part 126f can be arranged compactly by arranging the forward path 126c and the return path 126e in an orderly manner.

  As shown in FIG. 8, the fuel tank 20 has an outer surface 20c extending downward or obliquely downward, and the forward path 126c and the return path 126e of the U-turn portion 126f are arranged so as to be substantially parallel to the outer surface 20c. Yes. Thus, by arranging the U-turn part 126f along the shape of the fuel tank 20, the U-turn part 126f can be arranged more compactly.

  Further, according to the present embodiment, the U-turn portion 126 f is disposed below the fuel tank 20. Thereby, the space below the fuel tank 20 can be effectively utilized as the installation space for the U-turn portion 126f, and the low-pressure fuel pipe 126 can be arranged compactly.

  Further, according to the present embodiment, the high-pressure pump 123 has the pump chamber 123a (see FIG. 6), and when the fuel pressure in the pump chamber 123a exceeds a predetermined value, a part of the fuel is transferred to the third low-pressure fuel pipe 126. Perform constant pressure control to return. Therefore, inherently, pulsation is likely to occur in the third low-pressure fuel pipe 126. However, as described above, according to the present embodiment, the pulsation of the third low-pressure fuel pipe 126 can be suppressed, so that the performance degradation of the low-pressure pump 122 and the in-pipe injector 89 can be effectively suppressed.

  As shown in FIG. 6, the fuel tank 20 is detachably attached to the vehicle body frame 11 so as to rotate about the front end 20d as a fulcrum. Therefore, when the fuel tank 20 is rotated, the low-pressure pump 122 is also rotated integrally with the fuel tank 20. However, according to the present embodiment, the low-pressure fuel pipe 126 includes the U-turn part 126f, and the U-turn part 126f has flexibility. Therefore, even if the low-pressure pump 122 rotates together with the fuel tank 20, the low-pressure fuel pipes 124, 125, 126 are flexibly deformed following the movement, so that there is no possibility of damage. Therefore, when the fuel tank 20 is rotated for the purpose of vehicle parts inspection work or the like, it is not necessary to remove the low-pressure pump 122 from the fuel tank 20 in advance, and troublesome work is not necessary. For this reason, the convenience in attaching and detaching the fuel tank 20 is improved.

  In the present embodiment, the first low pressure fuel pipe 124 and the third low pressure fuel pipes 126a and 126b are formed by flexible hoses, and the high pressure fuel pipes 127a and 127b are formed by metal pipes. As described above, by properly using the materials in the low-pressure fuel pipes 124, 126a, 126b and the high-pressure fuel pipes 127a, 127b, the above-described effects can be favorably obtained while maintaining the reliability of fuel supply.

  The present invention is not limited to the above embodiment, and can be implemented in various other forms. Next, some modifications will be described.

  As shown in FIG. 6, in the above-described embodiment, the high-pressure side accumulator chamber 117 is provided between the delivery pipe 128 and the high-pressure pump 123, and the low-pressure side is further provided between the branch pipe 130 and the high-pressure pump 123. A pressure accumulating chamber 107 is provided. However, the high pressure side pressure accumulation chamber 117 or the low pressure side pressure accumulation chamber 107 is not necessarily required and can be omitted as appropriate. For example, as shown in FIG. 9, both the high pressure side pressure accumulation chamber 117 and the low pressure side pressure accumulation chamber 107 may be omitted.

  As shown in FIGS. 7 and 8, in the above embodiment, the U-turn portion 126f of the third low-pressure fuel pipe 126 is formed such that the forward path 126c is located above the return path 126e. However, as shown in FIGS. 10 and 11, it is of course possible to form the U-turn portion 126f of the third low-pressure fuel pipe 126 so that the forward path 126c is located below the return path 126e.

  As described above, the present invention is useful for straddle-type vehicles such as motorcycles.

1 is a left side view of a motorcycle according to an embodiment. It is an enlarged side view which shows an engine unit vicinity. It is an expanded sectional view near a cylinder head. It is a perspective view which shows a cylinder head cover. It is sectional drawing which shows the surrounding structure of a cylinder. It is a figure which shows the structure of a fuel system. It is a top view which shows arrangement | positioning of each apparatus and member which comprises a fuel system. It is a side view of the structure of FIG. It is a top view which shows arrangement | positioning of each apparatus and member of the fuel system which concerns on a modification. It is a top view which shows arrangement | positioning of each apparatus and member of the fuel system which concerns on another modification. It is a side view of the structure of FIG.

Explanation of symbols

10 Motorcycle (saddle-ride type vehicle)
11 Body frame 12 Steering head pipe (head pipe)
13 Main frame 20 Fuel tank 20c Fuel tank outer surface 29 Engine 29a Engine body 40 Cylinder head 41 Cylinder 50 Cylinder head cover 83 Combustion chamber 85 Intake pipe (intake passage)
87 Intake port (intake passage)
89 In-pipe injector 107 Low pressure side pressure accumulation chamber 117 High pressure side pressure accumulation chamber 122 Low pressure pump 123 High pressure pump 124 First low pressure fuel pipe 125 Second low pressure fuel pipe 126 Third low pressure fuel pipe 126c Outward path 126e Return path 126f U-turn section 127 High pressure fuel pipe 130 Branch pipe 189 In-cylinder injector

Claims (12)

An engine body having a combustion chamber and an intake passage for guiding air to the combustion chamber;
An in-cylinder injector for injecting fuel into the combustion chamber;
An in-pipe injector for injecting fuel into the intake passage;
A fuel tank for storing fuel;
A low-pressure pump provided in the fuel tank and conveying fuel in the fuel tank;
A first low-pressure fuel pipe for guiding the fuel supplied by the low-pressure pump;
A branch pipe for diverting the fuel guided by the first low-pressure fuel pipe;
A second low-pressure fuel pipe that is connected to the branch pipe and guides one fuel after the diversion toward the in-pipe injector;
A third low-pressure fuel pipe connected to the branch pipe and guiding the other fuel after the diversion;
A high-pressure pump that pressurizes the fuel guided by the third low-pressure fuel pipe and supplies the fuel toward the in-cylinder injector,
A straddle-type vehicle in which at least one of the first low-pressure fuel pipe and the third low-pressure fuel pipe includes a flexible U-turn portion.   The saddle riding type vehicle according to claim 1, wherein the U-turn portion is formed in the third low-pressure fuel pipe. A head pipe,
A pair of left and right main frames extending rearward from the head pipe,
The straddle-type vehicle according to claim 1, wherein the U-turn portion is disposed between the two main frames.   The straddle-type vehicle according to claim 3, wherein the U-turn portion is disposed between the low-pressure pump and the high-pressure pump.   The straddle-type vehicle according to claim 3, wherein the U-turn portion is formed so as to extend along the vehicle width direction and have an outward path and a return path that are adjacent to each other in the vehicle front-rear direction in plan view.   The straddle-type vehicle according to claim 3, wherein the U-turn portion is formed so as to have a forward path and a return path that extend along the vehicle width direction and are adjacent to each other in the vertical direction in a front view. The fuel tank has an outer surface extending downward or obliquely downward;
The straddle-type vehicle according to claim 6, wherein the outward path and the return path of the U-turn portion are arranged so as to be substantially parallel to the outer surface.   The saddle riding type vehicle according to claim 3, wherein the U-turn portion is disposed below the fuel tank.   The said high pressure pump has a pump chamber, and when the fuel pressure in the said pump chamber becomes more than predetermined value, it performs the constant pressure control which returns a part of fuel in the said pump chamber to the said 3rd low pressure fuel piping. Saddle riding type vehicle. With a body frame,
The straddle-type vehicle according to claim 1, wherein the fuel tank is detachably attached to the vehicle body frame so as to rotate about a front end portion of the fuel tank. A high-pressure fuel pipe connecting the high-pressure pump and the in-cylinder injector;
A part or all of the first low-pressure fuel pipe and the third low-pressure fuel pipe are made of a flexible hose,
The straddle-type vehicle according to claim 1, wherein the high-pressure fuel pipe is made of a metal pipe.   The straddle-type vehicle according to claim 1, which is a motorcycle.

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