JPH04252855A - Fuel supply system for motorcycle - Google Patents

Abstract

PURPOSE:To check any possible pulsation in fuel to the full as well as to reduce a variation in a fuel injection quantity by forming a fuel pipe, conducting the fuel to an injector from a fuel pump into an inverted U-shaped form, and installing a fuel filter being interposed in this fuel pipe in and around an inner bottom plate of a fuel tank. CONSTITUTION:A fuel pump 74 is attached to a crankcase, while a fuel pipe 83 leading to an injector 64 from this fuel pump 74 is bent into a nearly inverted U-shaped form at side view and the length is sufficiently lengthened, while a fuel filter 80 being interposed in the point midway in this fuel pipe 83 is housed in the inner part of a fuel tank 50 and is attached to the inner bottom plate. Accordingly, since fuel is passed through the sufficiently lengthened fuel pipe 83, the pulsation is well absorbed. Especially the fuel filter 80 is attached to the inside of the fuel tank 50, so that this filter 80 is made enlargeable in size and, what is more, a fuel pulsation absorbing effect becomes yet larger. Moreover, since the fuel pipe 83 is made by a rubber tube of at least a part of it, fuel pulsation becomes yet smaller owing to the elasticity.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system applied to a motorcycle having a fuel tank above a fuel injection engine.

0002

2. Description of the Related Art In a motorcycle having a fuel injection type engine, it has been considered to mechanically drive a fuel pump by a crankshaft. In this case, when the engine is operating at low speed, the pulsation period of the fuel discharged by the fuel pump increases, and this variation in fuel pressure may cause a problem in that the variation in fuel injection amount becomes large.

0003

OBJECTS OF THE INVENTION Accordingly, the present invention provides a motorcycle in which the pulsation of fuel supplied to an injector is sufficiently suppressed to reduce fluctuations in fuel injection amount when a fuel pump is mechanically driven by a crankshaft. The purpose is to provide a fuel supply device for

0004

According to the present invention, the object is to provide a fuel tank disposed above a fuel-injected engine, and a fuel pump provided in the crankcase of the engine and mechanically driven by the crankshaft of the engine. In the motorcycle, a fuel pipe that guides fuel from the fuel pump to the injector is formed with a substantially inverted U-shape on the side, a fuel filter is interposed in the fuel pipe, and the fuel filter is connected to the inner bottom plate of the fuel tank. This is achieved by a fuel supply device for a motorcycle, which is characterized in that it is disposed nearby.

[0005]

[Embodiment] Fig. 1 is a side view of a motorcycle that is an embodiment of the present invention, Fig. 2 is an enlarged view of its main parts, Fig. 3 is an air and fuel system diagram, and Fig. 4 is a line IV-IV in Fig. 2. FIG.

In FIGS. 1 and 2, reference numeral 10 is a vehicle body frame, which includes a head pipe 12, a down tube 14,
A main tube 16, a pair of left and right lower tubes 18 (only one shown) extending downward from the lower ends of these down tubes 14, and a pair of left and right seat pillar tubes that connect the rear end of the main tube 16 and the rear end of this lower tube 18. 19, a pair of left and right seat rails 20, a back stay 22, etc. The down tube 14 and the main tube 16 are connected by one reinforcing tube 24.

[0007] 26 is a front fork held by the head pipe 12, 28 is a steering front wheel, and 30 is a steering handlebar. 32 is a driving rear wheel, and 34 is a rear arm that holds the rear wheel 32 in a vertically movable manner.This rear arm 34 is given a downward return habit by a single cushion unit (not shown).

Reference numeral 36 is a liquid-cooled single-cylinder two-stroke engine that injects air and fuel into the combustion chamber. This engine 36 has its crankcase 38 fixed to the lower tube 18 and the seat pillar tube 19,
The upper part of the cylinder 40 is fixed to the main tube 16 via a stay 42. The output of this engine 36 is transmitted to the rear wheels 32 by a chain 44.

An exhaust pipe 46 extends rearward from the front of the cylinder 40, passing between the left and right lower tubes 18, passing above the right side of the engine 36. 48 is a pair of vertically long radiators on the left and right, 50 is a fuel tank, and 52 is a straddle-type driver's seat.

Reference numeral 54 denotes an air cleaner, which is disposed in a triangular space in side view surrounded by the seat rail 20, backstay 22, and seat pillar tube 19. Intake air is guided from the air cleaner 54 to the crankcase 38 of the engine 36 through an intake pipe 56, and is sucked into the crank chamber via a reed valve 58. This intake is piston 6
After being pre-pressurized in the crank chamber by the descent of 0, the scavenging passage 6
1 (Figure 3) to the combustion chamber.

In FIG. 2, 62 is a spark plug, and 64 is an injector. This injector 64 mixes air and fuel and injects the mixture into the combustion chamber from the end of the scavenging stroke of the piston to the compression stroke.

Next, this air and fuel injection system will be explained. The rotation of the crankshaft 62 (FIG. 3) of the engine 36 is transmitted to a plunger type air pump 72 and a gear type or trochoid type fuel pump 74 via a toothed belt 66 and one-way clutches 68, 70. The air pump 72 is of a liquid-cooled type, and a cooling liquid passage is formed in its cylinder body. This air pump 72 takes in outside air from an air filter 76 and pumps it to the injector 64 . The fuel pump 74 sucks fuel from the fuel tank 50 through a filter 78, and also sucks fuel from the fuel tank 50 through another fuel filter 8.
0 to the injector 64. 82 is a pulsation damper for absorbing fuel pulsation.

Here, the fuel pump 74 is connected to the crank case 3.
The fuel pipe 83 connected to the fuel pump 8 and extending from the fuel pump 74 to the injector 64 is bent into a substantially inverted U-shape when viewed from the side as shown in FIG. A fuel filter 80 interposed in the middle is housed inside the fuel tank 50 and attached to the inner bottom plate 50a of the fuel tank 50. Note that the fuel pipe 83 is made entirely or partially of a rubber tube.

The air and fuel pumped from the pumps 72 and 74 are mixed by the injector 64 and injected into the combustion chamber. The air pressure and fuel pressure supplied to the injector 64 are guided to a differential pressure regulator 84,
Here, the differential pressure between the two is controlled to be constant. Further, the fuel whose pressure is controlled to be constant here is fed under pressure to an intake injector 86 provided in the intake pipe 56. The fuel circulated through the injector 86 is returned to the fuel tank 50 through a fuel pressure regulator 88. In addition, two injectors 6
4 and 86 are electromagnetic type, and are electrically opened and closed by a control circuit (not shown).

In FIG. 3, reference numeral 90 denotes a starter motor, which drives both pumps 72 and 74 via one-way clutches 68 and 70 prior to rotating the crankshaft 62 when the engine 36 is started. 92 is a magneto generator provided at the other end of the crankshaft 62. Further, 94 is a throttle valve.

Therefore, when the engine is cold started, the injector 86 opens and fuel is mixed with the intake air and is taken in. At the same time, the injector 64 opens during the latter half of the scavenging stroke of the piston 60 and creates a mixture of air and fuel in the combustion chamber. Inject. After the engine warms up, the injector 86 closes and a mixture of fuel and air is injected only from the injector 64.

Next, the cooling system will be explained. crank case 3
A water pump 96 (FIG. 2) driven by the crankshaft 62 is disposed on the left side of the engine 8. The engine coolant cooled by the radiator 48 enters the water pump 96 from the bottom of the radiator 48 and is sent to each part of the engine 36. The air is then circulated from the top of the cylinder 40 through the thermostat 98 and back to the top of the radiator 48.

A portion of the coolant leaving the cylinder 40 is led to the air pump 72 by a pipe 100, and after cooling the air pump 72 is returned to the upper part of the radiator 48 by the pipe 102.

According to this embodiment, the fuel discharged from the fuel pump 74 passes through the sufficiently long fuel pipe 83, so that its pulsation is absorbed. In particular, since the fuel filter 80 is installed inside the fuel tank 50, the filter 80 can be made larger.
The effect of absorbing fuel pulsation becomes even greater. Furthermore, since at least a portion of the fuel pipe 83 is made of a rubber tube, the elasticity of the pipe 83 itself can be used to further reduce fuel pulsation. Therefore, injector 6
No. 4 can always control the injection amount with high precision without being affected by fuel pulsation.

FIG. 5 is a sectional view at a position corresponding to FIG. 4 showing another embodiment. In this embodiment, a fuel filter 80A interposed in a fuel pipe 83 is housed between the inner bottom plate 50b of the fuel tank 50A and the main tube 16, and is attached to the main tube 16 with a bracket. This embodiment also provides the same effects as the embodiments shown in FIGS. 1 to 4.

Although the embodiments described above are applied to a two-stroke engine with preloaded crank chamber, the present invention includes an application to a four-stroke engine. Furthermore, although in the above embodiment fuel and air are injected from the injector into the combustion chamber, the present invention may also inject these into the intake air, or may inject only the fuel into the combustion chamber or into the intake air.

[0024]

As described above, the present invention supplies fuel discharged from a fuel pump driven by an engine to an injector through a substantially inverted U-shaped fuel pipe on the side.
Since the fuel filter interposed in the middle of the fuel pipe is located near the inner bottom plate of the fuel tank, the fuel passage from the fuel pump to the injector is long, and fuel pulsation is sufficiently absorbed.

[Brief explanation of the drawing]

[Fig. 1] Side view of a motorcycle that is an embodiment of the present invention.

[
Figure 2: Enlarged view of main parts in Figure 1

[Figure 3] Air and fuel system diagram

[Fig. 4] Cross-sectional view taken along the line IV-IV in Fig. 2

[Fig. 5] Cross-sectional view of a position corresponding to line IV-IV in another embodiment

[Explanation of symbols]

36 Engine 38 Crank case 50, 50A fuel tank 50a, 50b Inner bottom plate 62 Crankshaft 64 Injector 80, 80A fuel filter 83 Fuel pipe

Claims (1)

[Claims] 1. A motorcycle comprising: a fuel tank disposed above a fuel injection type engine; and a fuel pump provided in a crankcase of the engine and mechanically driven by a crankshaft of the engine; A fuel pipe that guides fuel from the fuel pump to the injector is formed with a substantially inverted U-shape on the side, a fuel filter is interposed in the fuel pipe, and the fuel filter is disposed near the inner bottom plate of the fuel tank. Fuel supply system for motorcycles.