JP2002357162A - Carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent causing of malfunctioning of an engine and obstruction of restarting due to a bubble generated from fuel by heat generated in an electro-magnetically driven shutoff valve associated with a key switch provided in a fuel passage inlet part for preventing a dieseling phenomenon. SOLUTION: A valve seta 12 provided in an inlet of a fuel passage 8 and a valve element 20 provided in a tip of a plunger 19, piercing a mounting cylinder unit 16 of a solenoid-operated actuator are not opposed to each other in a valve chamber to be exposed in a fixed fuel chamber 6, the bubble generated in a through hole 17 of the mounting cylinder unit 16, is released toward an outer sideward region of the valve seat 12 so as not to reach the seat 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carburetor used for supplying fuel to an engine, and more particularly to a carburetor provided with an electromagnetically driven shut-off valve for closing a fuel passage when a key switch is turned off for stopping the engine. The present invention relates to a carburetor used for supplying fuel for a general-purpose engine.

[0002]

2. Description of the Related Art Since a carburetor generally sucks fuel into an intake passage by an engine suction negative pressure and supplies the fuel to the engine, even after a key switch is turned off, fuel is sucked and the engine continues to rotate. The dieseling phenomenon occurs. As a countermeasure, besides shutting off fuel suction from an idle port opened downstream of the closed throttle valve by an electromagnetic valve, or preventing it by a negative pressure drop due to air introduction, a certain type of 2. Description of the Related Art For a carburetor for a general-purpose engine, an inlet portion of a fuel passage is closed by an electromagnetic valve.

That is, in the carburetor for a general-purpose engine, a float-type constant fuel chamber is disposed below a carburetor body having a horizontal intake passage, and extends vertically from the bottom of the constant fuel chamber to reach the intake passage. A fuel passage is provided, and an inlet portion, which is a lower end of the fuel passage, is closed by an electromagnetic valve.

FIGS. 3A and 3B show an electromagnetically driven shut-off valve installed at the entrance of a fuel passage, and the shut-off valve closes the fuel passage when the key switch is turned off to prevent the dieseling phenomenon. FIG. 3 is a view showing a conventional example of the carburetor having the above configuration, and is attached to the lower surface of a carburetor main body having a lateral intake passage, and has a floating fuel chamber 51 inside, and a bottom of a bowl-shaped fuel container 52. A shutoff valve 53 is attached to the center. A columnar block 64 projecting downward from the carburetor body is inserted into the center of the constant fuel chamber 51, and a fuel passage 65 is provided therein.

The shut-off valve 53 is a mounting cylinder 5 projecting upward from an outer case 54 of an actuator containing a solenoid.
5 through the bottom of the fuel container 52 and a cylindrical valve body 56.
The lower end is screwed into the mounting cylinder 55 and the upper end is fitted into the block 64 and fixed to the fuel container 52. The valve body 56 has a valve chamber 57 inside, a main jet 58 attached to a peripheral side wall, and a valve seat 59 formed at the top of the valve chamber 57. The plunger 61 that is linearly reciprocated by the actuator penetrates through the mounting cylinder 55 and protrudes into the valve chamber 57, and has a valve body 62 at its tip. The plunger 61 connects the valve body 62 at the tip with the valve seat 5.
Even if it is eccentric to 9, it can swing so as to be completely seated, and loosely penetrates the through hole 63 of the mounting cylinder 55.

When the key switch is turned on, the actuator is excited, and the plunger 61 is attracted to separate the valve body 62 from the valve seat 59. For this reason, the fuel in the constant fuel chamber 51 is measured by the main jet 58 and enters the valve chamber 57, and is sent from the valve passage 60 to the fuel passage 65. Plunger 6
Enter the gap with 1.

[0007]

When the plunger 61 is sucked, the actuator generates heat by energization. In the conventional actuator shown in FIG. 3A, the fuel flowing into the gap of the through hole 63 is generated. Is heated to generate air bubbles, which rises up the valve chamber 57 as it reaches the narrow portion of the valve opening 60 or the fuel passage 65, thereby obstructing the flow of fuel due to surface tension, and irregularly entering the intake passage. By being delivered, the fuel flow rate becomes discontinuous or the air-fuel mixture is diluted. In addition, fuel enters the gap of the through-hole 63 instead of air bubbles, and the fuel is heated to generate air bubbles. This phenomenon is repeated irregularly, which causes engine malfunction.

The conventional example shown in FIG. 3B has been proposed for the purpose of solving the above-mentioned disadvantages (see Japanese Patent Application Laid-Open No. H11-50913). A closing member 66 for closing the open end of the gap to the valve chamber 57 is provided on the plunger 61 to prevent the release of bubbles during operation of the engine. However, when the key switch is turned off and the valve body 62 is seated on the valve seat 59, the air bubbles generated in the gap of the through hole 63 are released at a stroke and collect and accumulate in the upper part of the valve chamber 57, and this is accumulated. This is a major factor that hinders the flow of fuel and prevents restarting, especially at high temperatures.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem that bubbles generated by heating of a fuel entering a through-hole of a mounting cylinder by heat of an actuator cause malfunction of an engine or hinder a restart. What was done,
It is an object of the present invention to prevent the generated bubbles from reaching the valve seat, so that the operation and restart of the engine can be performed smoothly.

[0010]

SUMMARY OF THE INVENTION A block provided with a fuel passage in a constant fuel chamber formed inside a fuel container attached below a carburetor main body having an intake passage protrudes below the carburetor main body. And a valve seat is provided at an inlet of the fuel passage, and a valve body is provided at a tip of a plunger that penetrates a mounting cylinder body of a solenoid actuator protruded into the fuel container, The present invention solves the above-described problem that a carburetor having an electromagnetically driven shut-off valve that opens and closes a fuel passage by linearly reciprocating a plunger in conjunction with turning on and off a key switch of an engine has the following features. Solved.

That is, the valve seat of the shut-off valve and the valve body are exposed to the constant fuel chamber without facing each other in the valve chamber, and the bubbles generated in the through-hole penetrating the plunger of the mounting cylinder are removed from the constant fuel chamber. The discharge was performed toward the outer region of the valve seat.

During operation of the engine with the key switch turned on, the fuel in the through hole is heated by the heat of the actuator to generate bubbles, but the valve is in an open state in which the valve is located between the valve seat and the mounting cylinder. In this case, the air bubbles are diverted by the valve body and discharged directly into the constant fuel chamber toward the outer region of the valve seat, so that the fuel flow in the valve seat and the fuel passage is not obstructed. The object of smooth starting is achieved.

When the valve body is brought into contact with the tip of the mounting cylinder during the stroke of the plunger when the valve is opened to close the through hole, air bubbles are released during operation of the engine and the air bubbles are directed toward the valve seat. The worry of riding the fuel flow and reaching the valve seat is completely eliminated. In addition, when the key switch is turned off, air bubbles are released into the constant fuel chamber and do not collect on the lower surface of the valve seat, so that the engine can be operated and restarted more smoothly. Can be done. Further, when the valve seat is also used as the main jet, there is an advantage that the number of parts is reduced.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 and 2. A columnar block 3 is provided at the center of a carburetor main body 1 having a suction passage 2 extending in a lateral direction. And a bowl-shaped fuel container 4 is attached to the lower surface in a liquid-tight manner. The block body 3 is inserted into the center of the fuel container 4, and the inside of the fuel container 4 forms a constant fuel chamber 6 in which a float 5 for opening and closing a fuel valve (not shown) is incorporated.

The block body 3 has a hole 7 which is opened at the lower end and reaches near the intake passage 2, and the emulsion tube 9 is fixed inside. A main nozzle 10 is formed at the upper end of the emulsion pipe 9 so as to protrude from the venturi of the intake passage 2, and these form a fuel passage 8, particularly a fuel passage of a main system. The fuel passage of the low-speed system is formed by branching from the hole 7 on the inlet side of the emulsion pipe 9.

The shut-off valve 11, which communicates the inlet portion of the fuel passage 8 with the constant fuel chamber 6 during operation of the engine but shuts off when the engine is stopped, is electromagnetically driven, and its valve seat 12 has a hole serving as the inlet of the fuel passage 8. 7 is fitted and attached to the lower end. The valve seat 12 has a valve passage 13 communicating the constant fuel chamber 6 and the fuel passage 8, and a conical seat surface 14 extending downward on the inlet side. The dimensions are to define the maximum flow rate of Therefore, the valve seat 12 in the present embodiment also serves as a main jet for measuring fuel, and the number of parts is reduced.

The actuator of the shut-off valve 11 is of a solenoid type, and its outer case 15 has a mounting cylinder 16 projecting upward, and the mounting cylinder 16 penetrates the center of the bottom of the fuel container 4. Then, the nut 18 is protruded into the fixed fuel chamber 6 so as to face the block body 3, and is screwed to the mounting cylinder body 16.
And the outer case 15 sandwich the fuel container 4 and
5 is fixed to the fuel container 4 in a suspended state in a liquid-tight manner.

The outer case 15 incorporates a well-known solenoid type actuator including an electromagnet, a movable iron core, and a spring. A plunger 19 swingably connected to the movable iron core loosely penetrates the through hole 17 of the mounting cylinder 16. ing. At the tip of the plunger 19, a disc-shaped valve body 20 is provided.
The same conical contact surface 21 as 4 is formed. Further, a conical contact surface 22 that is in close contact with and overlaps the upper end edge of the through hole 17 that is the tip of the mounting cylinder 16 is formed on the outer peripheral edge of the lower surface of the valve body 20.

FIG. 2B shows the state of the shut-off valve 11 when the key switch is turned off and the engine is stopped. The plunger 19 moves upward by being pushed by the spring of the actuator, and the contact surface 21 on the upper surface of the valve body 20 is
The valve passage 13 which is an inlet of the fuel passage 8 is closed in close contact with the second seat surface 14. In addition, even if the center axis of the valve seat 12 and the valve body 20 is displaced due to a dimensional error or an improper mounting, the valve can be completely closed because the plunger 19 can swing.

FIGS. 1 and 2A show the state of the shut-off valve 11 when the key switch is turned on to operate the engine. The plunger 19 is attracted by the electromagnet of the actuator and moves downward. The valve body 20 is separated from the valve seat 12 to open the valve passage 13. Plunger 19
Can be set to an arbitrary stroke until the valve element 20 separates from the valve seat 12 and comes into contact with the mounting cylinder 16. Even if the valve element 20 is separated from the mounting cylinder 16, the plunger of the through hole 17 can be set. The bubbles generated by the fuel that has flowed into the gap with the upper portion 19 are deflected upward by the conical contact surface 22 on the lower surface, and are dispersed and discharged into the constant fuel chamber 6 without reaching the valve seat 12. be able to.

However, in the present embodiment, the valve body 2 is moved from the state in which the valve body 20 is seated on the valve seat 12 to the time when the plunger 19 is attracted by the electromagnet and moves downward.
The stroke until “0” comes into contact with the mounting cylinder 16 was set small, and the contact surface 22 on the lower surface hit the upper end edge of the through hole 17 during the valve opening stroke. The valve body 20 is the mounting cylinder 1
After being brought into contact with the tip of 6, it is firmly pressed by the attraction force of the electromagnet to maintain a close contact state, and completely encloses bubbles generated by fuel in the gap between the through hole 17 and the plunger 19. For this reason, there is a complete concern that the bubbles will be released from the gap and will ride on the fuel flow toward the valve seat 12 in the fuel container 4 and will reach the valve seat 12, obstructing the fuel flow in the valve passage 13 and the fuel passage 8. Will be resolved.

When the key switch is turned off to stop the engine, the electromagnet of the actuator is demagnetized and the plunger 19 is moved upward by the force of the spring, and the valve body 20 is seated on the valve seat 12, and the valve body 20 is seated on the valve seat 12 as shown in FIG. State. Mounting cylinder 1
6 are opened, and the air bubbles sealed therein are expelled into the constant fuel chamber 6 at once, and freely expand and ascend to the lower surface of the valve seat 12 so as not to collect. In particular, in the present embodiment, since the valve body 20 is disk-shaped and has a conical contact surface 22 on the outer peripheral edge of the lower surface, bubbles are directed toward the outer region of the valve seat 12 by the contact surface 22. To reach the lower surface of the valve seat 12 completely.

[0023]

As described above, according to the present invention, when the key switch is turned off to prevent gassing, the electromagnetically driven shut-off valve that closes the inlet of the fuel passage generates air bubbles generated by heating the fuel. The engine does not reach the inlet of the fuel passage even after the engine is stopped, even after the engine is stopped. Therefore, the fuel flow during the operation of the engine is discontinuous or the mixture is diluted so that the engine malfunctions. The inconvenience of hindering the start is eliminated, and the operation and restart of the engine can be performed smoothly.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIGS. 2A and 2B are enlarged partial views of FIG. 1 showing respective states of a shutoff valve opening and a shutoff valve closing valve.

FIGS. 3A and 3B are longitudinal sectional partial views showing different conventional examples.

[Explanation of symbols]

1 carburetor body, 2 intake path, 3 block body, 4
Fuel container, 6 constant fuel chamber, 8 fuel passage, 11
Shut-off valve, 12 valve seat, 14 seat surface, 16 mounting cylinder, 17 through hole, 19 plunger, 20 valve, 21 and 22 contact surface,

Claims (4)

[Claims] 1. A block provided with a fuel passage in a constant fuel chamber formed inside a fuel container attached to a lower surface of a carburetor main body having an intake passage, is projected and inserted below the carburetor main body. A valve seat is provided at an inlet of the fuel passage, and a valve body is provided at a tip end of a plunger that penetrates a mounting cylinder body of a solenoid-type actuator protruded into the fuel container. Wherein the plunger linearly reciprocates in response to the on / off operation of a key switch to open and close the fuel passage. Air bubbles that are exposed to the chamber and that are generated in a through hole that penetrates the plunger of the mounting cylinder body are discharged toward a region outside the valve seat of the constant fuel chamber. Vaporizer to butterflies. 2. The carburetor according to claim 1, wherein the valve body contacts the tip of the mounting cylinder body during the stroke of the plunger and closes the through hole when the valve is opened. 3. The valve body is disc-shaped, and has a contact surface on the upper surface, which contacts a seat surface of the valve seat, and a contact surface on the lower surface, which overlaps a tip of the mounting cylinder. 2
The vaporizer described in. 4. The carburetor according to claim 1, wherein the valve seat also serves as a main jet for measuring fuel.