JP2023004688A - engine fuel supply - Google Patents

Abstract

An object of the present invention is to provide a fuel supply device for an engine that can drain fuel from a fuel pump even if fuel remains in a fuel tank.
A fuel supply device (Y) for an engine includes a fuel supply section (32) for supplying fuel to an intake passage (P) of the engine, a fuel tank (34) connected to the fuel supply section (32) through a fuel path (Q), and a fuel path (Q). and a fuel cock 36 provided in the fuel path Q for opening and closing the fuel path Q. The fuel pump 37 is provided in the It is arranged on the downstream side of the fuel path Q. As shown in FIG.
[Selection drawing] Fig. 4

Description

The present invention relates to an engine fuel supply system.

2. Description of the Related Art Conventionally, there is known an engine fuel supply device that includes a fuel supply section (for example, a carburetor or fuel injection) that supplies fuel to an intake passage of an engine, and a fuel tank that is connected to the fuel supply section via a fuel path. It is

For example, Patent Literature 1 discloses a fuel having a pair of delivery pipes to which fuel injection valves are connected, a communication pipe that communicates the pair of delivery pipes, and a supply pipe that guides fuel in a fuel tank to the communication pipes. A delivery device is disclosed.

By the way, the engine sometimes leans greatly from its original posture. For example, when a lawnmower equipped with an engine is used for mowing on a steep slope, the engine tilts greatly from its original position. If the fuel tank descends below the fuel supply unit due to such inclination of the engine, fuel cannot be supplied from the fuel tank to the fuel supply unit, and the engine may stop. Therefore, a configuration is known in which a fuel pump is used to forcibly send fuel from a fuel tank to a fuel supply unit.

JP 2007-270682 A

When a fuel supply system with a fuel pump is not used for a long period of time, it is preferable to drain the fuel from the fuel pump to avoid deterioration of the fuel pump. However, depending on the layout of the components of the fuel supply system, it may not be possible to drain the fuel from the fuel pump while the fuel remains in the fuel tank.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel supply system for an engine that can drain fuel from a fuel pump even if fuel remains in the fuel tank.

One aspect of the present invention for solving the above problems is a fuel supply system (Y) for an engine, comprising: a fuel supply section (32) for supplying fuel to an intake passage (P) of an engine (5); a fuel tank (34) connected to a fuel supply section via a fuel path (Q); a fuel pump (37) provided in the fuel path for sending fuel toward the fuel supply section; a fuel cock (36) provided to open and close the fuel passage, and the fuel pump is arranged downstream of the fuel cock (36) in the fuel passage.

According to this aspect, by driving the engine with the fuel passage closed by the fuel cock, even if there is fuel remaining in the fuel tank, the fuel can be drained from the fuel pump. Therefore, user convenience is improved.

In the above aspect, the fuel tank may include a tank body (57) containing fuel, and at least part of the fuel pump may be arranged below the tank body.

According to this aspect, when restarting the engine by replenishing the fuel tank with fuel from a gas shortage state, even if the amount of fuel replenished to the fuel tank is relatively small, the fuel is supplied from the fuel tank to the fuel pump. It can be introduced by its own weight. Therefore, the engine can be stably restarted.

In the above aspect, the fuel supply system for the engine further includes a first fuel pipe (38) connecting the fuel tank and the fuel cock, at least a portion of the fuel cock being positioned below the tank body. The first fuel pipe includes an upstream pipe portion (81) extending downward from the lower end portion of the fuel tank, and a downstream pipe bent from the lower end portion of the upstream pipe portion and extending horizontally to the fuel cock. and a part (82).

According to this aspect, by simplifying the shape of the first fuel pipe, it is possible to smoothly introduce fuel from the fuel tank to the fuel cock. Therefore, the engine can be restarted more stably.

In the above aspect, the engine fuel supply device further includes a second fuel pipe (39) connecting the fuel cock and the fuel pump, and the fuel cock is the same as the fuel pump and the fuel supply unit. It may be arranged on a horizontal plane, and the second fuel pipe may extend horizontally from the fuel cock to the fuel pump.

According to this aspect, by simplifying the shape of the second fuel pipe, the fuel can be introduced smoothly from the fuel cock to the fuel pump. Therefore, the engine can be restarted more stably.

In the above aspect, the fuel cock may be arranged on the same straight line as the fuel pump and the fuel supply section, and the second fuel pipe may extend linearly from the fuel cock to the fuel pump.

According to this aspect, by further simplifying the shape of the second fuel pipe, the fuel can be more smoothly introduced from the fuel cock to the fuel pump. Therefore, the engine can be restarted more stably.

In the above aspect, the fuel supply device for the engine includes an insulator (33) arranged between the fuel supply portion and the cylinder head and defining a part of the intake passage, A pulse tube (41) connecting the insulator and the fuel pump may be further provided for transmission to the fuel pump.

According to this aspect, the pressure pulsation in the intake passage can be transmitted to the fuel pump with a simple configuration using the insulator.

In the above aspect, the fuel pump includes a hollow pump body (71) and a diaphragm (72) housed in the pump body, and the horizontal distance between the pump body and the insulator is the It may be narrower than the horizontal distance between the pump body and the fuel tank.

According to this aspect, compared to the case where the horizontal distance between the pump body and the fuel tank is narrower than the horizontal distance between the pump body and the insulator (for example, when the pump body is arranged adjacent to the fuel tank). to reduce the length of the pulse tube. As a result, the amplitude of pressure pulsation transmitted from the intake passage to the fuel pump via the pulse tube can be increased, so that the operating efficiency of the diaphragm can be increased. Also, by shortening the length of the pulse tube, the manufacturing cost of the pulse tube can be reduced.

In the above aspect, the fuel supply system for the engine further includes a third fuel pipe (40) connecting the fuel pump and the fuel supply section, and when viewed from the side of the engine, the pulse tube 3 It may intersect the fuel pipe.

According to this aspect, the fuel supply section, insulator, fuel pump, pulse tube, and third fuel tube can be densely packed in a relatively narrow space. As a result, the size of the fuel supply device can be reduced.

In the above aspect, the insulator-side portion of the pulse tube may be curved in a U-shape so as to protrude upward.

According to this aspect, it is possible to suppress the fuel in the intake passage from entering the fuel pump via the pulse tube. Therefore, deterioration of parts of the fuel pump due to fuel that has entered the fuel pump can be suppressed.

In the above aspect, the engine fuel supply system may further include a bracket extending horizontally below the fuel tank, and the fuel cock and the fuel pump may be fixed to the bracket.

According to this aspect, by fixing the fuel cock and the fuel pump to the same bracket, the fuel cock and the fuel pump can be accurately positioned.

In the above aspect, the engine includes an engine body (11) that rotatably supports a crankshaft (8), and the bracket is a first fixing plate (61) arranged along the side surface of the engine body. and a second fixing plate (62) protruding to the side of the engine body more than the first fixing plate, the fuel cock is fixed to the outer surface of the first fixing plate, and the fuel pump is , may be fixed to the inner surface of the second fixing plate.

According to this aspect, it is possible to protect the fuel pump from an external impact while improving the operability of the fuel cock.

In the above aspect, the engine includes an engine body (11) that rotatably supports a crankshaft (8), and a cover (14) that covers the upper side of the engine body. may be arranged below.

According to this aspect, by arranging the fuel pump in the empty space below the cover, the fuel supply device can be made compact.

According to the above aspect, even if fuel remains in the fuel tank, the fuel can be drained from the fuel pump.

1 is a perspective view showing a lawn mower according to one embodiment of the present invention; FIG. Schematic cross-sectional view showing an engine according to one embodiment of the present invention 1 is a perspective view showing the lower portion of an engine according to one embodiment of the present invention; FIG. 1 is a side view showing a fuel supply device according to one embodiment of the present invention; FIG.

<Lawn mower 1>
A lawn mower 1 (an example of a working machine) according to an embodiment of the present invention will be described below. Hereinafter, terms indicating directions such as front-rear, up-down, left-right, etc. are based on directions viewed from an operator (not shown) who operates the lawn mower 1 .

Referring to FIG. 1, a lawn mower 1 includes a base member 3, a handle 4 attached to the rear portion of the base member 3, and a general-purpose engine 5 attached to the central portion of the base member 3 (hereinafter simply referred to as "engine 5”), and a blade 6 (an example of a working part) and a fan (not shown) arranged below the engine 5. The constituent elements of the lawn mower 1 will be described in order below.

The base member 3 of the lawn mower 1 has a flat shape elongated in the front-back direction and the left-right direction. The base member 3 has a hollow shape with an open bottom surface. A central portion of the base member 3 bulges upward.

A handle 4 of the lawn mower 1 is a member that is held by an operator who operates the lawn mower 1 . The handle 4 extends upward from the rear portion of the base member 3 .

The engine 5 of the lawn mower 1 is, for example, an air-cooled single-cylinder engine. The engine 5 has a rotatable crankshaft 8 . The crankshaft 8 is rotatably provided around a rotation axis X extending in the vertical direction. That is, the engine 5 is a vertical type engine in which the rotation axis X of the crankshaft 8 extends vertically. A PTO shaft 9 (power take-off shaft) is provided at the lower end of the crankshaft 8 .

A blade 6 of the lawn mower 1 is attached to a PTO shaft 9 and is provided so as to be integrally rotatable with the PTO shaft 9 . The blade 6 is housed inside the base member 3 .

A fan (not shown) of the lawn mower 1 is attached to the PTO shaft 9 so as to be rotatable integrally with the PTO shaft 9 . The fan is housed inside the base member 3 .

<Operation of lawnmower 1>
In the lawn mower 1 configured as described above, when the engine 5 is driven, the PTO shaft 9 rotates. When the PTO shaft 9 rotates in this manner, a fan (not shown) attached to the PTO shaft 9 rotates together with the PTO shaft 9 . When the fan rotates in this way, the lawn mower 1 is given buoyancy by the airflow generated by the fan, and the lawn mower 1 rises from the ground. Further, when the PTO shaft 9 rotates as described above, the blade 6 attached to the PTO shaft 9 rotates integrally with the PTO shaft 9 to mow the grass. As described above, the lawn mower 1 according to the present embodiment is a floating hover mower that mows grass while floating above the ground.

<Engine 5>
Next, the engine 5 will be further explained. Referring to FIG. 1, engine 5 includes engine body 11, intake device 12 arranged on the right side of engine body 11, exhaust device 13 arranged on the left side of engine body 11, and engine body 11. and a cover 14 covering the upper side. The components of the engine 5 will be described in order below, but the description of the exhaust device 13 and the cover 14 will be omitted.

<Engine body 11>
1 and 2, an engine body 11 of the engine 5 includes a crankcase 16, a cylinder 17 extending rearward from the crankcase 16, a cylinder head 18 extending rearward from the cylinder 17, and a cylinder head 18 extending rearward from the cylinder head 18. and a head cover 19 that covers the

The aforementioned crankshaft 8 is rotatably supported in the central portion of the crankcase 16 . A piston 21 is housed in the cylinder 17 so as to be able to reciprocate. Piston 21 is connected to crankshaft 8 via connecting rod 22 .

Cylinder head 18 defines combustion chamber 23 with piston 21 . The combustion chamber 23 is connected to an intake port 24 opened on the right side surface of the cylinder head 18 . An intake port 26 that is opened and closed by an intake valve 25 is provided between the combustion chamber 23 and the intake port 24 . The combustion chamber 23 is connected to an exhaust port 27 opened on the left side surface of the cylinder head 18 . An exhaust port 29 that is opened and closed by an exhaust valve 28 is provided between the combustion chamber 23 and the exhaust port 27 . The exhaust port 27 is connected to the exhaust device 13 described above.

<Intake device 12>
1 to 3, the intake device 12 of the engine 5 includes an air cleaner 31, a carburetor 32 (an example of a fuel supply section), an insulator 33, a fuel tank 34, a bracket 35, and a fuel cock 36. , a fuel pump 37 , first to third fuel tubes 38 to 40 and a pulse tube 41 . Members of the intake device 12 excluding the air cleaner 31 constitute a fuel supply device Y for the engine 5 . The constituent elements of the intake device 12 will be described in order below.

Referring to FIG. 1 , air cleaner 31 of intake device 12 protrudes rearward to the right with respect to engine body 11 . An air filter (not shown) for cleaning the air is housed inside the air cleaner 31 . The air cleaner 31 is omitted except for FIGS. 1 and 2. FIG.

Referring to FIG. 2 , the carburetor 32 and insulator 33 of the intake device 12 define an intake passage P connecting the air cleaner 31 and the combustion chamber 23 together with the intake port 24 of the cylinder head 18 . Hereinafter, when a member defining the intake passage P is described as "upstream" or "downstream", it means "upstream" or "downstream" in the air flow direction in the intake passage P. As shown in FIG.

The carburetor 32 of the intake device 12 includes a throttle body 43 , a spray nozzle 44 housed in the throttle body 43 , a throttle valve 45 and a choke valve 46 .

A throttle passage 48 is provided in the upper portion of the throttle body 43 of the carburetor 32 . The throttle passage 48 forms an upstream portion of the intake passage P. As shown in FIG. An upstream end of the throttle passage 48 is connected to the air cleaner 31 . A downstream end of the throttle passage 48 is connected to the intake port 24 of the cylinder head 18 via the insulator 33 . A tapered venturi portion 49 is provided in the central portion of the throttle passage 48 .

A float chamber 50 is provided below the throttle body 43 of the carburetor 32 . The float chamber 50 contains fuel (see symbol F in FIG. 2). A carburetor-side joint 51 that communicates with the float chamber 50 protrudes from the outer peripheral surface of the throttle body 43 .

A spray nozzle 44 of the carburetor 32 extends vertically. The upper end of the spray nozzle 44 is arranged in the venturi section 49 of the throttle passage 48 . A lower end of the spray nozzle 44 is arranged in the float chamber 50 .

A throttle valve 45 of the carburetor 32 is accommodated in a throttle passage 48 downstream of the venturi portion 49 . The throttle valve 45 is connected to a governor device (not shown). The governor device adjusts the amount of air-fuel mixture supplied to the combustion chamber 23 by changing the opening degree of the throttle valve 45 according to the rotational speed of the crankshaft 8 .

A choke valve 46 of the carburetor 32 is housed in a throttle passage 48 upstream of the venturi portion 49 . 3 and 4, choke valve 46 is connected to automatic choke device 53 . The automatic choke device 53 adjusts the ratio of fuel in the air-fuel mixture by changing the degree of opening of the choke valve 46 according to the temperature of the engine body 11 . Specifically, when the temperature of the engine body 11 is lower than a predetermined temperature, the automatic choke device 53 decreases the opening of the choke valve 46 to increase the ratio of fuel in the air-fuel mixture. This makes it easier to start the engine 5 when it is cold.

Referring to FIG. 2, insulator 33 of intake device 12 is arranged between throttle body 43 and cylinder head 18 to suppress heat transfer therebetween. The insulator 33 is fixed to the cylinder head 18 together with the throttle body 43 . The insulator 33 is made of resin and has an annular shape. The internal space of the insulator 33 defines part of the intake passage P (more specifically, the portion between the throttle passage 48 and the intake port 24). An insulator-side joint 55 that communicates with the internal space of the insulator 33 protrudes from the outer peripheral surface of the insulator 33 . 3 and 4, the insulator 33 is provided integrally with the automatic choke device 53. As shown in FIG.

1 and 4, the fuel tank 34 of the intake device 12 includes a tank body 57 containing fuel, a cap 58 detachably attached to the upper end of the tank body 57, and a lower end of the tank body 57. and a tank side joint 59 protruding from. The tank body 57 is arranged below the cover 14 and fixed to the engine body 11 . The cap 58 protrudes above the cover 14 .

Referring to FIG. 3, bracket 35 of intake device 12 is arranged below cover 14 . Bracket 35 extends horizontally below fuel tank 34 . The bracket 35 is formed by bending a single sheet metal. The bracket 35 is fixed to the right side surface of the engine body 11 .

The bracket 35 includes a first fixing plate 61 , a second fixing plate 62 arranged behind the first fixing plate 61 , and an auxiliary plate 63 arranged in front of the first fixing plate 61 . The first fixed plate 61 is arranged along the right side surface of the engine body 11 . A boundary portion between the first fixing plate 61 and the second fixing plate 62 and a boundary portion between the first fixing plate 61 and the auxiliary plate 63 are stepped. Therefore, the second fixing plate 62 and the auxiliary plate 63 protrude to the right (lateral side) of the engine body 11 more than the first fixing plate 61 . A first through hole 64 is formed at the boundary between the first fixing plate 61 and the auxiliary plate 63 , and a second through hole 65 is formed at the boundary between the first fixing plate 61 and the second fixing plate 62 .

Referring to FIG. 2, fuel cock 36, fuel pump 37 and first to third fuel pipes 38 to 40 of intake device 12 constitute a fuel path Q connecting fuel tank 34 and carburetor 32. As shown in FIG. Hereinafter, when the members constituting the fuel path Q are described as "upstream" or "downstream", they indicate "upstream" or "downstream" in the direction of fuel flow in the fuel path Q. As shown in FIG.

Referring to FIG. 3, fuel cock 36 of intake device 12 is arranged below cover 14 . The fuel cock 36 is attached to the right surface (outer surface) of the first fixing plate 61 of the bracket 35 . A cock lever 67 is provided on the fuel cock 36 . The fuel cock 36 opens and closes the fuel path Q according to the operator's operation of the cock lever 67 .

Referring to FIG. 4 , the entire fuel cock 36 is arranged below the tank body 57 of the fuel tank 34 . The fuel cock 36 is arranged on the same horizontal plane as the fuel pump 37 and the carburetor 32 . More specifically, the fuel cock 36 is arranged in line with the fuel pump 37 and the carburetor 32 . A first cock-side joint 68 protrudes forward and a second cock-side joint 69 protrudes rearward from the outer peripheral surface of the fuel cock 36 .

2 and 4, the fuel pump 37 of the intake device 12 is arranged downstream of the fuel cock 36 in the fuel path Q. As shown in FIG. In other words, the fuel pump 37 is arranged between the fuel cock 36 and the carburetor 32 in the fuel path Q. As shown in FIG.

The fuel pump 37 includes a hollow pump body 71 and a diaphragm 72 housed in the pump body 71 . The diaphragm 72 divides the internal space of the pump body 71 into a pump chamber R1 and a pulsation transmission chamber R2. A first pump-side joint 74 that communicates with the pump chamber R1 protrudes from the lower front portion of the outer peripheral surface of the pump main body 71 . A second pump-side joint 75 that communicates with the pump chamber R1 protrudes from the rear upper portion of the outer peripheral surface of the pump main body 71 . The second pump-side joint 75 is arranged above the first pump-side joint 74 in order to suppress retention of steam in the pump chamber R1. A third pump-side joint 76 that communicates with the pulsation transmission chamber R2 protrudes from the center of the rear portion of the outer peripheral surface of the pump main body 71 .

Referring to FIG. 3, fuel pump 37 is arranged below cover 14 . A fuel pump 37 is positioned between the fuel cock 36 and the carburetor 32 . The fuel pump 37 is arranged between the right side surface of the engine body 11 and the second fixing plate 62 of the bracket 35 . A pair of fixing pieces 77 protrude from the outer peripheral surface of the pump body 71 of the fuel pump 37 . A pair of fixing pieces 77 are fixed to the left surface (inner surface) of the second fixing plate 62 of the bracket 35 .

Referring to FIG. 4, the upper portion of fuel pump 37 is arranged at the same height as tank body 57 of fuel tank 34 . The lower portion of the fuel pump 37 is arranged below the tank body 57 of the fuel tank 34 . A horizontal distance G1 between the pump body 71 of the fuel pump 37 and the insulator 33 is narrower than a horizontal distance G2 between the pump body 71 of the fuel pump 37 and the fuel tank 34 .

3 and 4, the first fuel pipe 38 of the intake device 12 includes an upstream pipe portion 81 extending downward from the lower end portion of the tank main body 57 of the fuel tank 34 and a rearward portion of the upstream pipe portion 81 extending downward from the lower end portion of the upstream pipe portion 81 . and a downstream pipe portion 82 that is bent toward the fuel cock 36 and extends in the front-rear direction (horizontal direction) to the fuel cock 36 . The upper end (upstream end) of the upstream pipe portion 81 is connected to the tank side joint 59 of the fuel tank 34 . A rear end (downstream end) of the downstream pipe portion 82 is connected to the first cock side joint 68 of the fuel cock 36 . The downstream pipe portion 82 passes through the first through hole 64 of the bracket 35 .

A second fuel pipe 39 of the intake device 12 extends linearly in the front-rear direction (horizontal direction) from the fuel cock 36 to the fuel pump 37 . A front end (upstream end) of the second fuel pipe 39 is connected to a second cock side joint 69 of the fuel cock 36 . A rear end (downstream end) of the second fuel pipe 39 is connected to a first pump-side joint 74 of the fuel pump 37 . The second fuel pipe 39 passes through the second through hole 65 of the bracket 35 .

A front end (upstream end) of the third fuel pipe 40 of the intake device 12 is connected to a second pump-side joint 75 of the fuel pump 37 . A rear end (downstream end) of the third fuel pipe 40 is connected to a carburetor-side joint 51 of the carburetor 32 . A central portion of the third fuel pipe 40 in the front-rear direction is inclined downward from the front side (the fuel pump 37 side) toward the rear side (the carburetor 32 side).

A rear end portion of the pulse tube 41 of the intake device 12 is connected to an insulator-side joint 55 of the insulator 33 . A front end of the pulse tube 41 is connected to a third pump-side joint 76 of the fuel pump 37 . A rear portion 41A (a portion on the insulator 33 side) of the pulse tube 41 is curved in a U shape so as to protrude upward. A rear portion 41 A of the pulse tube 41 passes above the automatic choke device 53 . A front portion 41B (a portion on the side of the fuel pump 37) of the pulse tube 41 extends in the front-rear direction (horizontal direction). The front portion 41B of the pulse tube 41 intersects the center portion of the third fuel pipe 40 in the front-rear direction as viewed from the right side of the engine 5 .

<Supply of Fuel to Throttle Passage 48>
Referring to FIG. 2, when the engine 5 is driven, pressure pulsation occurs in the intake passage P as the piston 21 reciprocates. This pressure pulsation in the intake passage P is transmitted to the pulsation transmission chamber R2 of the fuel pump 37 via the pulse tube 41. As shown in FIG. As a result, the diaphragm 72 of the fuel pump 37 vibrates, and the pressure in the pump chamber R1 of the fuel pump 37 repeatedly increases and decreases.

When the pressure in the pump chamber R1 of the fuel pump 37 decreases, the fuel contained in the fuel tank 34 is sucked into the pump chamber R1 of the fuel pump 37 through the first fuel pipe 38, the fuel cock 36 and the second fuel pipe 39. be. When the pressure in the pump chamber R1 of the fuel pump 37 increases, the fuel sucked into the pump chamber R1 of the fuel pump 37 is discharged to the float chamber 50 of the carburetor 32 through the third fuel pipe 40. In this manner, fuel pump 37 pumps fuel from fuel tank 34 to float chamber 50 of carburetor 32 .

Further, when the engine 5 is driven, the air introduced from the air cleaner 31 into the throttle passage 48 passes through the venturi portion 49 of the throttle passage 48, so that the venturi portion 49 of the throttle passage 48 has a negative pressure with respect to the float chamber 50. do. As a result, the fuel contained in the float chamber 50 is sprayed through the spray nozzle 44 into the venturi portion 49 of the throttle passage 48 . Fuel is thereby supplied to the throttle passage 48 . The fuel supplied to the throttle passage 48 is mixed with the air introduced from the air cleaner 31 into the throttle passage 48, and then introduced into the combustion chamber 23 through the inner space of the insulator 33 and the intake port 24 of the cylinder head 18. .

<effect>
When the fuel supply device Y having the fuel pump 37 as described above is not used for a long period of time, it is preferable to drain the fuel from the fuel pump 37 in order to avoid deterioration of the fuel pump 37 . However, if the fuel pump 37 is arranged on the upstream side of the fuel passage Q from the fuel cock 36, even if the engine 5 is driven with the fuel passage Q closed by the fuel cock 36, the fuel can be drained from the fuel pump 37. Can not. Therefore, when the fuel pump 37 is arranged on the upstream side of the fuel passage Q from the fuel cock 36, in order to drain the fuel from the fuel pump 37, the fuel passage Q is opened by the fuel cock 36, and the fuel inside the fuel tank 34 is opened. It is necessary to drive the engine 5 until the fuel runs out. That is, the fuel cannot be drained from the fuel pump 37 when the fuel remains in the fuel tank 34 . Therefore, there is a possibility that the user's convenience may be deteriorated.

On the other hand, in this embodiment, the fuel pump 37 is arranged downstream of the fuel passage Q from the fuel cock 36 . By adopting such an arrangement, by driving the engine 5 with the fuel passage Q closed by the fuel cock 36, even if fuel remains in the fuel tank 34, the fuel can be drained from the fuel pump 37. can. Therefore, user convenience is improved.

Further, in this embodiment, a portion of the fuel pump 37 is arranged below the tank body 57 of the fuel tank 34 . By adopting such an arrangement, when refueling the fuel tank 34 from a gas shortage state and restarting the engine 5, even if the amount of fuel replenished to the fuel tank 34 is relatively small, the fuel tank Fuel can be introduced by its own weight from 34 to fuel pump 37 . Therefore, the engine 5 can be stably restarted.

The first fuel pipe 38 includes an upstream pipe portion 81 extending downward from the lower end portion of the tank main body 57 of the fuel tank 34 and a downstream pipe bent from the lower end portion of the upstream pipe portion 81 and extending horizontally to the fuel cock 36 . a portion 82; As a result, by simplifying the shape of the first fuel pipe 38 , fuel can be introduced smoothly from the fuel tank 34 to the fuel cock 36 . Therefore, the engine 5 can be restarted more stably.

The fuel cock 36 is arranged on the same horizontal plane as the fuel pump 37 and the carburetor 32 , and the second fuel pipe 39 extends horizontally from the fuel cock 36 to the fuel pump 37 . As a result, by simplifying the shape of the second fuel pipe 39 , fuel can be introduced smoothly from the fuel cock 36 to the fuel pump 37 . Therefore, the engine 5 can be restarted more stably.

Further, the fuel cock 36 is arranged on the same straight line as the fuel pump 37 and the carburetor 32 , and the second fuel pipe 39 extends linearly from the fuel cock 36 to the fuel pump 37 . As a result, by further simplifying the shape of the second fuel pipe 39 , the fuel can be more smoothly introduced from the fuel cock 36 to the fuel pump 37 . Therefore, the engine 5 can be restarted more stably.

Also, the pulse tube 41 connects the insulator 33 and the fuel pump 37 so as to transmit pressure pulsation in the intake passage P to the fuel pump 37 . As a result, pressure pulsation in the intake passage P can be transmitted to the fuel pump 37 with a simple configuration using the insulator 33 .

Further, the horizontal distance G1 between the pump main body 71 and the insulator 33 is narrower than the horizontal distance G2 between the pump main body 71 and the fuel tank 34 . Therefore, when the horizontal gap G2 between the pump main body 71 and the fuel tank 34 is narrower than the horizontal gap G1 between the pump main body 71 and the insulator 33 (for example, the pump main body 71 is arranged adjacent to the fuel tank 34). case), the length of the pulse tube 41 can be shortened. As a result, the amplitude of pressure pulsation transmitted from the intake passage P to the fuel pump 37 via the pulse tube 41 can be increased, so that the operating efficiency of the diaphragm 72 can be increased. Also, by shortening the length of the pulse tube 41, the manufacturing cost of the pulse tube 41 can be reduced.

Also, in a side view of the engine 5 , the pulse tube 41 intersects with the third fuel tube 40 . Thereby, the carburetor 32, the insulator 33, the fuel pump 37, the pulse tube 41 and the third fuel tube 40 can be densely packed in a relatively narrow space. As a result, the fuel supply device Y can be made compact.

A rear portion 41A (a portion on the insulator 33 side) of the pulse tube 41 is curved in a U shape so as to protrude upward. As a result, the fuel in the intake passage P can be prevented from entering the fuel pump 37 via the pulse tube 41 . Therefore, deterioration of parts of the fuel pump 37 (in particular, the diaphragm 72) due to fuel that has entered the fuel pump 37 can be suppressed.

Also, the fuel cock 36 and the fuel pump 37 are fixed to the bracket 35 . By fixing the fuel cock 36 and the fuel pump 37 to the same bracket 35 in this manner, the fuel cock 36 and the fuel pump 37 can be accurately positioned.

Also, the fuel cock 36 is fixed to the outer surface of the first fixing plate 61 of the bracket 35 , and the fuel pump 37 is fixed to the inner surface of the second fixing plate 62 of the bracket 35 . As a result, the fuel pump 37 can be protected from external shocks while improving the operability of the fuel cock 36 .

Also, the fuel pump 37 is arranged below the cover 14 . Accordingly, by arranging the fuel pump 37 in the empty space below the cover 14, the fuel supply device Y can be made compact.

<Modification>
In the above embodiment, only part of the fuel pump 37 is arranged below the tank body 57 . On the other hand, in other embodiments, the entire fuel pump 37 may be arranged below the tank body 57 .

In the above embodiment, the entire fuel cock 36 is arranged below the tank body 57 . On the other hand, in other embodiments, only part of the fuel cock 36 may be arranged below the tank body 57 .

In this embodiment, the pulse tube 41 connects the insulator 33 and the fuel pump 37 . On the other hand, in other embodiments, the pulse tube 41 may connect a member other than the insulator 33 (for example, the crankcase 16 ) and the fuel pump 37 .

In the above embodiment, the carburetor 32 is used as the fuel supply section. On the other hand, in other embodiments, fuel injection may be used as the fuel supply.

In the above embodiment, the engine 5 is an air-cooled single-cylinder engine. On the other hand, in other embodiments, the engine 5 may be an engine of a type other than an air-cooled type (for example, a water-cooled engine), or may be a multi-cylinder engine.

In the above embodiment, the configuration of the present invention is applied to the floating lawn mower 1 . On the other hand, in other embodiments, the configuration of the present invention may be applied to a traveling lawn mower having wheels for traveling. Furthermore, in other embodiments, the configuration of the present invention may be applied to a work machine other than the lawnmower 1, such as a high-pressure washer.

Although the specific embodiments have been described above, the present invention is not limited to the above-described embodiments and modifications, and can be widely modified.

5: General-purpose engine 8: Crankshaft 11: Engine body 14: Cover 18: Cylinder head 32: Carburetor (an example of a fuel supply unit)
33: Insulator 34: Fuel tank 35: Bracket 36: Fuel cock 37: Fuel pump 38: First fuel pipe 39: Second fuel pipe 40: Third fuel pipe 41: Pulse tube 41A: Rear part of pulse tube (insulator side part)
57: Tank main body 61: First fixed plate 62: Second fixed plate 71: Pump main body 72: Diaphragm 81: Upstream pipe portion 82: Downstream pipe portion P: Intake passage Q: Fuel path Y: Fuel supply device

Claims (12)

a fuel supply unit that supplies fuel to an intake passage of the engine;
a fuel tank connected to the fuel supply unit via a fuel path;
a fuel pump that is provided in the fuel path and sends fuel toward the fuel supply unit;
a fuel cock provided in the fuel path for opening and closing the fuel path,
The fuel supply device for an engine, wherein the fuel pump is arranged downstream of the fuel cock in the fuel path. The fuel tank comprises a tank body containing fuel,
2. The engine fuel supply system according to claim 1, wherein at least part of said fuel pump is arranged below said tank body. further comprising a first fuel pipe connecting the fuel tank and the fuel cock;
At least part of the fuel cock is arranged below the tank body,
The first fuel pipe is
an upstream pipe extending downward from the lower end of the fuel tank;
3. The fuel supply system for an engine according to claim 2, further comprising a downstream pipe bent from a lower end of said upstream pipe and extending horizontally to said fuel cock. further comprising a second fuel pipe connecting the fuel cock and the fuel pump;
The fuel cock is arranged on the same horizontal plane as the fuel pump and the fuel supply unit,
4. The engine fuel supply system according to claim 3, wherein said second fuel pipe extends horizontally from said fuel cock to said fuel pump. The fuel cock is arranged on the same straight line as the fuel pump and the fuel supply unit,
5. The engine fuel supply system according to claim 4, wherein said second fuel pipe extends linearly from said fuel cock to said fuel pump. an insulator disposed between the fuel supply portion and the cylinder head and defining a portion of the intake passage;
The engine according to any one of claims 1 to 5, further comprising a pulse tube connecting said insulator and said fuel pump to transmit pressure pulsation in said intake passage to said fuel pump. fuel supply. The fuel pump includes a hollow pump body and a diaphragm housed in the pump body,
7. The engine fuel supply system according to claim 6, wherein the horizontal distance between said pump body and said insulator is narrower than the horizontal distance between said pump body and said fuel tank. further comprising a third fuel pipe connecting the fuel pump and the fuel supply unit;
8. The engine fuel supply system according to claim 6, wherein the pulse tube intersects with the third fuel tube in a side view of the engine. The engine fuel supply system according to any one of claims 6 to 8, wherein the insulator-side portion of the pulse tube is curved in a U shape so as to protrude upward. further comprising a bracket extending horizontally below the fuel tank;
10. The engine fuel supply system according to claim 1, wherein said fuel cock and said fuel pump are fixed to said bracket. The engine comprises an engine body that rotatably supports a crankshaft,
The bracket is
a first fixing plate arranged along the side surface of the engine body;
a second fixing plate protruding to the side of the engine body more than the first fixing plate,
The fuel cock is fixed to the outer surface of the first fixing plate,
11. The engine fuel supply system according to claim 10, wherein said fuel pump is fixed to the inner surface of said second fixing plate. The engine includes an engine body that rotatably supports a crankshaft, and a cover that covers the upper side of the engine body,
The engine fuel supply system according to any one of claims 1 to 11, wherein the fuel pump is arranged below the cover.

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