JP2002048006A - Auxiliary fuel supply device of carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply fuel to an intake air passage from a long bag-shaped fuel pump at starting time and accelerating time of an engine by using intake pressure of the engine or pulsing pressure of a crankcase. SOLUTION: The pulsing pressure (the intake pressure of a 4-stroke internal combustion engine) of the crankcase of a 2-stroke engine is made to act on an outer peripheral surface of the long bag-shaped fuel pump 34 composed of a restorable material such as rubber built in a carburetor body 2 via a through hole 27a penetrating through a valve stem 27 of a butterfly throttle valve 28. The fuel inside the fuel pump 34 is supplied to a passage 35a between a high speed fuel adjusting needle valve 29 and a check valve 32. A manual opening-closing valve C is arranged for opening and closing the through hole 27a in an idle position of the throttle valve 28, and the fuel of the fuel pump 34 is supplied to the intake air passage 14 via the check valve 32 by opening the opening-closing valve C when starting the engine. The through hole 27a opens the opening-closing valve C in a fully opening position of the throttle valve 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary fuel supply device for a carburetor in which a long-bag type auxiliary fuel pump works to increase fuel during cold start of an internal combustion engine and increase fuel during acceleration.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of emission control, the fuel flow rate of a carburetor has been set to be thin, and an accelerating fuel pump has been equipped so as not to sacrifice acceleration performance. Also,
Preferably, the engine is started at the lowest possible rotational speed for safety reasons. In particular, in the case of an engine mounted on a portable work machine, it is desired that the engine can be started below the connection point of the centrifugal clutch where the rotation of the engine is not transmitted to the blade. Further, it is preferable that after the engine is started, the warm-up operation is quickly achieved, and after the warm-up, the engine is returned to the idle operation by a simple operation.

A fuel pump for increasing the amount of fuel during a cold start of an engine is disclosed in Japanese Patent Application Laid-Open No. 8-165954, and a fuel pump for increasing the amount of fuel during an acceleration of the engine is disclosed in Japanese Patent Publication No. Sho 62-578.
No. 22 discloses this. However, these fuel pumps have complicated structures, and do not achieve an increase in fuel when the engine is started and an increase in fuel when the engine is accelerated.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to utilize a long-bag fuel pump at the time of starting and accelerating an engine by utilizing the intake pressure of the engine or the pulsating pressure of a crankcase. Is to provide an auxiliary fuel supply device for a carburetor which has a simple structure and supplies the fuel to an intake path.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a configuration of the present invention provides a pulsating pressure of a crank chamber of a two-stroke internal combustion engine or an intake pressure of a four-stroke internal combustion engine on a valve shaft of a butterfly throttle valve. Through the through hole, acts on the outer peripheral surface of a long bag-shaped fuel pump made of a resilient material such as rubber incorporated in the carburetor body, and allows the fuel inside the fuel pump to be a high-speed fuel adjustment needle valve and a check valve. (Backlash bleed prevention valve) In a butterfly-type throttle valve type membrane carburetor for supplying to a passage between the throttle valve and a manual bleed valve that opens and closes the through hole at an idle position of the throttle valve, An on-off valve is opened to supply the fuel of the fuel pump to the intake path via the check valve, and the through-hole opens the on-off valve at the fully opened position of the throttle valve.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a long bag type or spoid type fuel pump is accommodated in an accommodation chamber formed in a vaporizer main body, and the inside (outlet) of the fuel pump is checked by a check valve (back bleed prevention valve). ) To connect to the high-speed fuel injection holes,
Pulsating pressure of crank chamber (or intake pressure of intake pipe)
Through the external passage, the through hole provided in the valve shaft of the throttle valve, and the valve groove of the valve member externally fitted to the valve shaft. At the time of cold start of the engine, when the valve member is rotated by the operation lever, pulsating pressure is introduced into the storage chamber through the valve groove of the valve member and the through hole of the valve shaft,
The long bag or the spoid is crushed to supply the fuel inside the spoid to the intake passage. This state is automatically released when the valve shaft is rotated from the idle position in the opening direction. On the other hand, during acceleration of the engine, when the valve shaft is rotated to near the fully open position, the valve groove of the valve member communicates with the through hole of the valve shaft again, pulsating pressure is supplied to the storage chamber, and the fuel of the long bag or the spoid is discharged. It is supplied to the intake path.

[0007]

1 is a plan sectional view of an auxiliary fuel supply device for a carburetor according to the present invention, and FIG. 2 is a side sectional view of the auxiliary fuel supply device. A butterfly-shaped throttle valve 28 supported on a valve shaft 27 is provided in the middle of the intake passage 14 penetrating the carburetor body 2.
The high-speed fuel injection hole 3 is located upstream of the throttle valve 28 in the intake passage 14.
3 is provided with a low-speed fuel injection hole 26 near the closed position of the throttle valve 28. A throttle valve lever 36 is connected to an end of the valve shaft 27, and a return spring 37 is wound around a portion of the valve shaft 27 between the throttle valve lever 36 and the main body 2. One end of the return spring 37 is locked to the throttle valve lever 36, and the other end of the return spring 37 is locked to the main body 2, and the force of the return spring 37 urges the throttle valve 28 to the closed position shown in FIG.

As shown in FIG. 2, a main fuel pump A has a cover plate 4 connected to an upper end of a main body 2 with a membrane 6 interposed therebetween, and a pulsating pressure chamber 9 above the membrane 6 and a pump below the membrane 6. The chambers 8 are respectively formed. The pulsating pressure chamber 9 is connected via a passage 7 to a crank chamber of a two-stroke engine (or, in the case of a four-stroke engine, an intake pressure inlet of an intake pipe). Fuel in a fuel tank (not shown) is sucked into the pump chamber 8 through the passage 12 and the check valve 10,
Through the check valve 5, the strainer 3, the passage 13, and the inflow valve 15, the gas is discharged to the constant pressure fuel chamber 20 of the constant pressure fuel supply mechanism B.

The constant pressure fuel supply mechanism B has a membrane 2
A cover plate 22 having an atmosphere hole 23 is connected to the fuel cell 1 with the air pressure chamber 1 interposed therebetween, and a constant pressure fuel chamber 20 is defined above the membrane 21 and an atmosphere chamber 24 is defined below the membrane 21. A lever 18 is rotatably supported by a support shaft 17 inside the constant-pressure fuel chamber 20. One end of the lever 18 is locked to the lower end of the inflow valve 15,
The other end is urged into engagement with the center of the membrane 21 by the force of the spring 19. The fuel in the constant pressure fuel chamber 20 is supplied to the intake passage 14 through the passage 38, the low speed fuel adjustment needle valve 25, and the low speed fuel injection hole 26. The fuel in the constant-pressure fuel chamber 20 is supplied to the passage 16, the high-speed fuel adjusting needle valve 29, the annular groove, the radial passage, and the axial passage of the passage member 31, the check valve 32 (back bleed prevention valve), and the high-speed fuel injection hole 33. Is supplied to the intake path 14 through When the fuel in the constant pressure fuel chamber 20 becomes low, the membrane 21 receiving the intake negative pressure acting on the constant pressure fuel chamber 20 and the atmospheric pressure of the atmosphere chamber 24 rises, the lever 18 is rotated counterclockwise, and the inflow valve 15
Is lowered and opened, and the fuel from the main fuel pump A passes through the passage 1
3. The fuel is supplied to the constant pressure fuel chamber 20 via the inflow valve 15. In this manner, a predetermined amount of fuel is always kept at a constant pressure in the constant-pressure fuel chamber 20.

According to the present invention, the fuel pump 34 is
A long bag or spoid 34b having elastic resilience, such as rubber, is housed in a housing chamber 34a formed inside the housing. The inside of the spoiler 34b has a passage 35a and a check valve 32.
And is connected to the high-speed fuel injection hole 33. On the other hand, accommodation room 3
The passage 40, the valve groove 42a of the on-off valve C, the through hole 27a of the valve shaft 27, the valve of the on-off valve C, Groove 42
a, It is supplied through a passage 35. The on-off valve C is provided with a pair of valve grooves 42a having a point symmetry on a cylindrical valve member 42 fitted on a valve shaft 41 and fitted on a valve housing 41 (see FIG. 3).
Is formed. The outer peripheral side of each valve groove 42a is long in the circumferential direction and always communicates with the passage 40 or the passage 35a.
The inner circumferential side of 2a is short in the circumferential direction, and the communication with the through hole 27a is cut off by the relative rotation between the valve member 42 and the valve shaft 27.

As shown in FIG. 1, an operation lever 42b is integrally connected to an outer end of the valve member 42. A notch 44a and a protruding piece 44b are formed in a lock plate 44 provided on the valve member 42. A spring 43 is wound around a portion between the main body 2 of the valve member 42 and the locking plate 44. One end 43a of the spring 43 is locked by a lever 46a supported by the main body 2 by a support shaft 45, and the other end 43b of the spring 43 is locked by a projecting piece 44b of a locking plate 44. As shown in FIG. 5, the locking claw 46 is urged to rotate clockwise about the support shaft 45 by the force of the spring 43, the locking plate 44 is urged to rotate counterclockwise, and the protruding piece 44b is moved to the operating lever 42b. At the edge. A release lever 47 integral with the locking claw 46 is configured to straddle a radial pin 48 supported on the end of the valve shaft 27.

Next, the operation of the auxiliary fuel supply device for a carburetor according to the present invention will be described. As shown in FIG. 3, when the engine is stopped, the throttle valve 28 is in the idle position, and the operating lever 42 b is moved by the force of the spring 43 so that the projecting piece 44
It is in a state of being flipped upward through b. Valve member 4
The second valve groove 42a is shut off from the through hole 27a of the valve shaft 27. When the engine is started, when the operating lever 42b is pressed down, as shown in FIG. 2, a pair of valve grooves 42a arranged in the circumferential direction is formed.
Communicates with the through hole 27 a of the valve shaft 27. Accordingly, the passage 40 and the passage 35 are communicated with each other, the pulsating pressure of the crank chamber acts on the storage chamber 34a to crush the spoil 34b, and the fuel inside the spoid 34b is discharged to the passage 35a, the check valve 32, the high-speed The fuel is supplied to the intake path 14 through the fuel injection holes 33. Thus, the amount of fuel at the time of starting is increased, and starting of the engine at the time of cold is smoothly achieved.

After the engine is started, when the valve shaft 27 is slightly rotated in the opening direction (clockwise) of the throttle valve 28, the release lever 47 is flipped up by the pin 48. At this time, lock claw 4
6 is disengaged from the notch 44a of the lock plate 44, and FIG.
As shown in (1), the locking plate 44 is rotated counterclockwise by the force of the spring 43. Accordingly, the on-off valve C returns to the closed position shown in FIG.

To accelerate the engine, the valve shaft 27 is moved to the throttle valve 2
8, when it is rotated to the vicinity of the fully open position, as shown in FIG.
Even when the valve member 42 is in the initial position, the through hole 27a is
2a, the passage 40 and the passage 35 are communicated with each other,
The intake pressure is introduced into the storage chamber 34a, and the fuel of the fuel pump 34 is supplied to the intake passage 14 through the passage 35a, the check valve 32, and the high-speed fuel injection hole 33.

[0015]

As described above, according to the present invention, the pulsation pressure of the crank chamber of the two-stroke internal combustion engine or the intake pressure of the four-stroke internal combustion engine is passed through the through hole provided in the valve shaft of the butterfly throttle valve, and Butterfly that acts on the outer peripheral surface of a long bag-shaped fuel pump made of a resilient material such as rubber built in to supply fuel inside the fuel pump to a passage between a high-speed fuel adjustment needle valve and a check valve. In the diaphragm type membrane carburetor, a manual on-off valve for opening and closing the through hole at an idle position of the throttle valve is provided, and when the engine is started, the on-off valve is opened to supply the fuel of the fuel pump to the check valve. At the fully open position of the throttle valve, the through-hole opens the on-off valve.When the engine starts, the fuel amount increases and a rich air-fuel mixture is supplied to the engine. Start of the engine is obtained. Also, when the engine is accelerated, the fuel amount increases and a rich mixture is supplied to the engine, so that smooth engine acceleration can be obtained.

With a simple configuration, fuel can be supplied to the intake passage from the common long bag type fuel pump at the time of starting and accelerating the engine, which helps to reduce manufacturing costs.

[Brief description of the drawings]

FIG. 1 is a plan sectional view of an auxiliary fuel supply device for a carburetor according to the present invention.

FIG. 2 is a side sectional view showing a state at the time of starting the auxiliary fuel supply device.

FIG. 3 is an enlarged side sectional view showing a normal state of the auxiliary fuel supply device.

FIG. 4 is a side sectional view showing a state of the auxiliary fuel supply device during acceleration.

FIG. 5 is a side cross-sectional view showing the locked state of the auxiliary fuel supply device.

FIG. 6 is a side sectional view showing a state when the auxiliary fuel supply device is released.

[Explanation of symbols]

A: Main fuel pump B: Constant-pressure fuel supply mechanism C: On-off valve 2: Vaporizer body 3: Strainer 5: Check valve 6:
Membrane 8: Pump chamber 9: Pulsating pressure chamber 10: Check valve 14:
Intake path 15: Inflow valve 17: Support shaft 18: Lever 2
0: constant pressure fuel chamber 21: membrane 22: cover plate 24: atmosphere chamber 25: low speed fuel adjustment needle valve 26: low speed fuel injection hole 2
7: Valve shaft 27a: Through hole 28: Throttle valve 29: High-speed fuel adjustment needle valve 32: Check valve 33: High-speed fuel injection hole 34
a: accommodation room 34: fuel pump 34b: spoid 3
6: throttle valve lever 37: return spring 41: valve housing 42a: valve groove 42: valve member 42b: operating lever 43: spring 44: locking plate 44a: notch 44
b: protruding piece 46: locking claw 46a: lever 47: release lever 48: pin

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F02M 17/04 F02M 17/04 CDKL

Claims (7)

[Claims] 1. A pulsating pressure of a crank chamber of a two-stroke internal combustion engine or an intake pressure of a four-stroke internal combustion engine passes through a through hole provided in a valve shaft of a butterfly throttle valve and restores rubber or the like built in the carburetor body. Butterfly type throttle valve type membrane carburetor which acts on the outer peripheral surface of a long bag type fuel pump made of a material and supplies the fuel inside the fuel pump to a passage between a high speed fuel adjusting needle valve and a check valve. A manual opening / closing valve that opens and closes the through hole at the idle position of the throttle valve, opens the opening / closing valve when starting the engine, and supplies the fuel of the fuel pump to the intake passage through the check valve; The auxiliary fuel supply device for a carburetor, wherein the through hole opens the on-off valve when the throttle valve is fully opened. 2. The fuel pump operates as an auxiliary fuel pump when the throttle valve is in the open position at the idle position of the throttle valve, and when the throttle valve is in the open position when the throttle valve is fully open.
2. The fuel pump of claim 1, wherein the fuel pump acts as an accelerating fuel pump.
An auxiliary fuel supply device for a carburetor according to claim 1. 3. The auxiliary fuel supply device for a carburetor according to claim 1, wherein said on-off valve is arranged concentrically with a valve shaft of a throttle valve. 4. A projecting piece of a locking plate disposed concentrically with a valve shaft engages with an operating lever of the on-off valve by a force of a spring wound on an outer peripheral surface of the on-off valve, and is connected to a carburetor body. 2. The auxiliary fuel supply device for a carburetor according to claim 1, wherein a supported locking claw is engaged with a notch of the locking plate to prevent the on-off valve from returning from an open position to a closing direction. 3. 5. When the valve shaft is rotated in the opening direction in a locking state for preventing return of the on-off valve from the open position to the closing direction, the locking claw is disengaged by a pin of the valve shaft, and The auxiliary fuel supply of a carburetor according to claim 4, wherein the valve returns to the closed position. 6. The auxiliary fuel supply device for a carburetor according to claim 4, wherein said lock plate pushes said throttle valve from an idle position to an opening direction when said on-off valve is in a locked state. 7. A spring for urging the on-off valve in a return direction,
The auxiliary fuel supply device for a carburetor according to claim 1, wherein the lock pawl is biased in a return direction.