JPS6238548B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an auxiliary fuel supply mechanism suitable for being incorporated into a carburetor of a two-stroke engine used as a drive source for a chain saw or a bush cutter.

The carburetor of an internal combustion engine has a built-in fuel supply mechanism for supplying an appropriate amount of fuel to the engine depending on the operating conditions of the engine. There is a problem with the startability of the engine in etc.

In order to improve the startability of this engine, a recess is formed in the intake passage of the carburetor, a porous member for retaining auxiliary fuel is placed in the recess, and the auxiliary fuel is retained in the porous member. It was suggested that.

The auxiliary fuel held in the porous member is supplied to the engine by the intake negative pressure that acts when the engine is started, so that the mixture concentration at the time of engine startup is increased, thereby increasing the engine speed. Startability is improved.

However, since the porous member is provided in the intake passage inside the carburetor, the size of the porous member, that is, the amount of auxiliary fuel retained is limited. The auxiliary fuel mechanism may not be able to reserve a sufficient amount of auxiliary fuel to smoothly perform idling immediately after startup. Furthermore, since a relatively large value of intake negative pressure acts on the intake passage in which the porous member is provided during normal operation of the engine, this large intake negative pressure causes the air to remain in the porous member. There was a risk that fuel would be sucked into the engine during normal operation when auxiliary fuel was not needed after idling following startup.

Therefore, an object of the present invention is to be able to reserve a sufficient amount of auxiliary fuel to smoothly start the engine and the subsequent idling operation without supplying auxiliary fuel to the engine when it is not needed. The object of the present invention is to provide an auxiliary fuel supply mechanism.

Basically, the present invention provides an auxiliary fuel storage means for receiving auxiliary fuel to be stored from an auxiliary fuel supply device, without providing the auxiliary fuel storage means inside the carburetor, which is subject to large limitations on its capacity, and instead allows the auxiliary fuel storage means to be stored outside the carburetor. The retention means is provided in association with the intake port of the carburetor, and by moving the retention means to a position opposite to the intake port and close to the intake port by means of the operating means, the fuel is sucked into the internal combustion engine through the intake port. auxiliary fuel of the retention means is supplied to the engine together with the air flowing through the intake, and the operating means directs the retention means from the intake where the retention means is not strongly influenced by the air flow passing through the intake. By moving it to a distant position,
The present invention is characterized in that supply of auxiliary fuel from the storage means when unnecessary is reliably prevented.

Furthermore, the present invention is characterized in that the auxiliary fuel fed to the retention means and falling from the retention means is returned to the fuel tank via a return pipe.

The features of the present invention will become clearer from the following description of an illustrated embodiment in which the present invention is applied to a diaphragm type carburetor.

As shown in FIG. 1, a carburetor 10 according to the present invention includes a carburetor body 14 in which an intake passage 12 is formed, and a throttle valve 16 for making the effective diameter of the intake passage 12 variable. include.

One end of the intake passage 12 returns to an inlet 12a open to one side of the carburetor main body 14, and the other end returns to an outlet 12b open to the other side of the carburetor main body 14. The exhaust port 12b is connected to the intake pipe 1 made of a heat insulating material.
8 to an air intake 22 of an internal combustion engine, for example a two-stroke engine 20. A bench lily portion 24 is provided near the intake port 12a in the intake passage 12.
is formed.

The carburetor 10 is provided with a conventionally well-known fuel supply mechanism 32 that includes a fuel pump 26 and a diaphragm chamber 30 whose peripheral wall is partially formed by a diaphragm 28 .

Fuel pump 26 is a diaphragm pump having a diaphragm 34 and a pair of check valves 36,38. The engine 20 is placed in a diaphragm chamber 40 formed on one side of the diaphragm 34.
The pulsating operating pressure, for example the crank chamber pressure in a two-stroke engine, is introduced via the line 42. Therefore, when the engine 20 is in operation, the fuel pump 26 operates as is well known in the art.
Fuel in the fuel tank 44 is sucked into a pump chamber 48 formed on the other side of the diaphragm 34 through a fuel pipe 46 extending from the fuel tank and one check valve 36, and this sucked fuel is passed through the other check valve 38 and one check valve 36. It is pumped into the diaphragm chamber 30 through the passage 50.

A valve member 52 is provided within the diaphragm chamber 30 to connect and disconnect the passage 50 . This valve member 52 is interlocked with the diaphragm 28 via a swing lever 56 that engages with the diaphragm 28 and receives the biasing force of the compression spring 54 .

Two fuel delivery passages 58, 60 extend from the diaphragm chamber 30. One of the feed passages 58 returns to a plurality of idling ports 62 that open to the intake passage 12, and the other feed passage 60 returns to a main port 64 that opens to the intake passage 12. Check valves 6 for blocking the flow of fluid toward the diaphragm chamber 30 are provided in both the feed passages 58 and 60.
6, 68 and adjusting screws 70, 72 for fuel adjustment are provided, respectively.

During normal operation after idling following the startup of the engine 20, the fuel in the diaphragm chamber 30 is mixed with the air taken in from the intake port 12a as a mixture due to the intake negative pressure acting on the intake passage 12. The air is sucked into the engine 20 from each port 62, 64 depending on its operating condition. Further, the valve member 52 opens and closes due to the negative pressure acting on the diaphragm chamber 30, so that fuel is intermittently introduced into the diaphragm chamber 30 through the passage 50.

Therefore, according to the fuel supply mechanism 32, the normal operation after idling following the start of the engine 20 is suitably maintained and controlled.

However, the fuel from the supply mechanism 26 alone cannot supply the engine 20 with a rich air-fuel mixture sufficient to improve the startability of the engine 20 and maintain good idling operation following startup.

For this purpose, the carburetor 10 is provided with an auxiliary fuel supply mechanism 74 according to the present invention. This auxiliary fuel supply mechanism 74 includes a chamber 76 that communicates with the suction port 12a formed in the carburetor main body 14.
a housing 78 supported on the carburetor body 14 to define a auxiliary fuel retention means 80 disposed within the chamber 76; and means 82 for operating the auxiliary fuel retention means.

The housing 78 is connected to the inlet 1 of the carburetor 10.
An air intake port 86 provided with an air filter 84 is provided at a portion corresponding to 2a. housing 78
covers the entire vaporizer 10 in the illustrated example, but
Alternatively, a housing may be used that defines a chamber that communicates with the inlet 12a without covering the entire carburetor 10.

In the example shown in FIG. 1, the operating means 82 is an operating rod 8 disposed parallel to the longitudinal central axis of the intake passage 12 provided in the carburetor main body 14.
8. The operating rod 88 is connected to the housing 78
It extends from the chamber 76 to the outside of the housing 78 via a bearing portion 90 provided in the housing 78, and is slidable in the longitudinal direction of the operating rod. A support plate 92 is fixed to one end of the operating rod 88 located in the chamber 76, and extends parallel to and perpendicular to the operating rod and facing the one side surface of the carburetor body 14 where the suction port 12a is open. has been done. Further, an operating knob 94 is fixed to the other end of the operating rod 88.

The retaining means 80 is supported by the support plate 92, and the retaining means 80 is made of an oil-resistant porous member such as a sponge member or a sintered metal member. This porous member 80 has a support plate 9
2, a base portion 80a fixed to a surface facing the suction port 12a, and a truncated conical protrusion portion 80b protruding from the base portion toward the suction port 12a. The outer diameter at the tip of the protruding portion 80b is smaller than the diameter of the suction port 12a to allow the tip to fit into the suction port 12a.

Therefore, when the operator pushes in the operating knob 94, the retaining means, that is, the porous member 80 is moved to face and be close to the suction port 12a, as shown in phantom lines in FIG. The porous member 80 can be moved to position (A), and in this close position (A), the tip of the protruding portion 80b of the porous member 80 is received in the suction port 12a. Furthermore, by pulling the operation knob 94, the porous member 80 can be moved along a straight path in a direction away from the suction port 12a. The member 80 is connected to the inlet 1
It can be moved to a position (B) away from 2a.

Although the protruding portion 80b of the porous member 80 can be made unnecessary, in order to more reliably supply the auxiliary fuel to the engine 20, which will be described later, it is possible to provide the porous member with the protruding portion as described above. desirable.

The retention means or porous member 80 is supplied with auxiliary fuel from a fuel supply device 96. In the illustrated example, the fuel supply device 96 is a hand pump provided in the housing 78.

The hand pump 96 includes a cap-shaped elastic body 100 defining a pump chamber 98 and a pair of check valves 102 and 104. A suction port 106 of the pump chamber 98 in which one of the check valves 102 is provided communicates with the diaphragm chamber 30 through a suction path 108. Also, the discharge port 110 of the pump chamber 98 in which the other check valve 104 is provided
A discharge pipe 112 is connected to the porous member 80, and the end of the discharge pipe is connected to the porous member 80 located in the vicinity.
Open above.

Prior to starting the engine 20, the operating knob 94 is operated, and the porous member 80 is moved to the adjacent position A by operating the operating knob, and the hand pump 98 is repeatedly pressed. be done. When the hand pump 98 is operated, negative pressure is applied within the diaphragm chamber 30 due to the suction action of the pump, so that regardless of the non-operating state of the engine 20, that is, the non-operating state of the fuel pump 26. , the fuel in the fuel tank 44 is introduced into the diaphragm chamber 30 through the pump chamber 48 of the fuel pump 26.

Therefore, the hand pump 96 functions as a suction type primer pump, and when the diaphragm chamber 30 is filled with fuel, the suction fuel is pumped through the suction path 108, the pump chamber 98 and It is supplied to the porous member 80 located at the adjacent position A through the discharge pipe 112, and is sucked and held by the porous member.

After supplying auxiliary fuel to the porous member 80 located at the adjacent position A by operating the pump 96, the engine 20 is started by, for example, recoil. When negative pressure is applied to the intake passage 12 by this starting operation, fuel is drawn into the intake passage 12 from the idling port 62 by this intake negative pressure. At the same time, an air flow is generated that flows from the air intake port 86 of the housing 78 toward the suction port 12a, and together with this air flow, the porous member 80 located at the position A adjacent to the suction port 12a
The auxiliary fuel held in the air is sequentially drawn into the intake passage 12. As a result, the concentration of the air-fuel mixture supplied to the engine 20 at the time of starting the engine is increased, making it easier to start the engine.

During idling operation subsequent to the start of the engine 20, a relatively large amount of auxiliary fuel is retained in the retention means 80, so that the retention means 80
Auxiliary fuel is subsequently supplied to the engine 20 from. Moreover, the fuel reserved in the retaining means 80 is sequentially supplied starting from the fuel located near the suction port 12a, and the fuel located near the support plate 92 is affected by the air flow flowing toward the suction port 12a. Therefore, as the idling operation progresses, the amount of auxiliary fuel supplied from the retention means 80 is preferably gradually reduced.

Therefore, even in cold weather, the engine 20 can be easily started, and smooth idling operation can be maintained following the startup.

When the engine shifts to idling operation which does not require the supply of auxiliary fuel from the retention means 80, the retention means 80 is moved to position B away from the intake port 12a by operating the operation knob 94. At this remote position B, the auxiliary fuel remaining in the retention means 80 is not affected by the strong influence of the air flowing toward the suction port 12a, so that the remaining auxiliary fuel flows through the suction port 12a. It is not supplied to the engine 20 through the process. As a result, it is possible to reliably prevent the supply of auxiliary fuel under operating conditions that do not require the supply of auxiliary fuel, and it is possible to maintain good operation of the engine 20.

There is a risk that the remaining auxiliary fuel from the holding means 80 located at position B away from the suction port 12a may fall from the holding means 80 due to vibrations or the like. In order to utilize this fallen fuel for operation of the engine 20, as shown in FIG. 2, a recess 1 is provided in the housing 78 to receive the fallen fuel.
14, and can be returned to the fuel tank 44 via a return pipe 116 that communicates the inside of the recess with the inside of the fuel tank 44.

A check valve 11 is provided in the recess 114 to prevent backflow of fuel from the fuel tank 44 into the housing 78.
It is preferable to provide 8. The check valve 118 shown in FIG. Return to

FIG. 3 shows an example of an operating means 82' that automatically performs the above-described operation of the holding means 80, and the structure of the vaporizer 10 itself shown in FIG. 3 is the same as that shown in FIG. 1. .

The operating means 82' includes a temperature-sensitive element 120 that is activated by a temperature change in the engine 20, and a device 122 that converts the operation of the temperature-sensitive element into a rocking movement of the holding means 80. In the illustrated example, the temperature sensing element 120 is made of a bimetal whose one end is in contact with the engine 20 and is held between the engine and the intake pipe 18.
The conversion device 122 has one end connected to the bimetal 1.
a connecting rod 124 coupled to the other end of 20 and extending through housing 78 and into chamber 76;
and located within said chamber 76 and pivot 12 .
6, the lever 128 is swingably supported on the housing 78 via a pivot shaft 126.
The portion remote from the connecting rod 124 is pivotally connected to the other end of the connecting rod 124 via a pin 130.

The lever 128 is provided with a support part 92' for supporting the retention means 80, and the retention means 8 is provided on the surface of the support part facing the suction port 12a.
0 is fixed.

In the non-operating state of the engine, the bimetal 1
20 is slightly warped as shown in phantom lines in FIG. 3, with the result that the lever 128 is held in the position shown in phantom lines, so that the retaining means 80 is It is held at a position A' opposite to and close to the suction port 12a, which is similar to that described above.

The holding means 80 at this close position A' is
As described above, the auxiliary fuel supplied from the auxiliary fuel supply device 96 is supplied to the engine 20 when the engine 20 is started, to facilitate the start of the engine 20 and to maintain smooth idling operation that continues after the engine 20 is started.

As the temperature of the engine rises due to the continuation of this idling operation, the bimetal 120 deforms toward the linear shape shown by the solid line in FIG. 3 as the temperature rises. Due to this deformation of the bimetal 120, the connecting rod 124 is displaced to the right in the figure along its longitudinal direction, and the lever 128 pivotally connected to the rod is rotated clockwise about the pivot shaft 126. , said retaining means 80 is moved along an arcuate path towards the position indicated by reference numeral B' in FIG. When the engine 20 reaches a temperature at which the supply of auxiliary fuel becomes unnecessary, the retention means 80 is held at a position B' away from the intake port 12a.

At this remote position B', the auxiliary fuel remaining in the retention means 80 is not so strongly influenced by the airflow flowing toward the suction port 12a as to be sucked into the suction port 12a, and is therefore unnecessary. It is possible to reliably prevent the supply of auxiliary fuel at times.

1 to 3 show an example in which the holding means 80 is movable in a direction away from the one side surface of the vaporizer main body 14 where the suction port 12a is provided. It can be made movable parallel to one side.

Further, in the above description, an example was explained in which the auxiliary fuel supply mechanism according to the present invention is incorporated into a diaphragm type carburetor, but it can be incorporated not only in this diaphragm type carburetor but also in various types of carburetors such as a float type carburetor. Further, the auxiliary fuel delivery device can be provided independently of the primer pump.

According to the present invention, as described above, since the auxiliary fuel storage means is provided outside the carburetor main body, the capacity of the storage means is increased, so that the auxiliary fuel can be supplied even during idling operation following engine startup. A sufficient amount of auxiliary fuel can be retained to obtain Therefore, the engine can be started easily and the idling operation subsequent to the start can be performed smoothly.

Furthermore, since it is possible to reliably prevent the supply of the auxiliary fuel remaining in the storage means when unnecessary,
The operating condition of the engine can be maintained in good condition without causing malfunction of the engine due to the supply of unnecessary auxiliary fuel.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal section showing a carburetor incorporating an auxiliary fuel supply mechanism according to the present invention, FIG. 2 is a partial sectional view showing another embodiment of the present invention, and FIG.
The figure is a drawing similar to FIG. 1 showing still another embodiment of the present invention. 10: Carburetor, 12: Intake passage, 12a: Inlet, 20: Internal combustion engine, 32: Fuel supply mechanism, 4
4: Fuel tank, 74: Auxiliary fuel supply mechanism, 7
6: Chamber, 78: Housing, 80: Auxiliary fuel storage means, 80a: Base portion, 80b: Projection portion, 82, 82': Operating means, 86: Air intake port, 88: Operating rod, 96: Auxiliary fuel supply device, 114: recess, 116: return pipe, 118: check valve, 120: temperature sensing element, 122: conversion device,
A, A': close positions, B, B': distant positions.

Claims (1)

[Scope of Claims] 1. A mechanism for supplying auxiliary fuel to an internal combustion engine, which is equipped with a fuel supply mechanism and a carburetor provided with an intake port for taking in air, in order to facilitate the starting of the engine. a housing defining a chamber having an intake port and communicating with the intake port; and a housing that is disposed within the chamber and is displaced between a position opposite to and close to the intake port and a position remote from the intake port. an auxiliary fuel retention means comprising a removably supported porous member, a device for delivering fuel to the auxiliary fuel retention means, and an operation for moving said auxiliary fuel retention means to said proximate and remote positions; An auxiliary fuel supply mechanism for an internal combustion engine, including means. 2. The auxiliary fuel supply mechanism according to claim 1, wherein the porous member includes a base portion and a protruding portion that projects from a surface of the base portion facing the suction port so as to be fit into the suction port. . 3. The operating means includes an operating rod having one end connected to the porous member and the other end penetrating the housing and extending outward from the housing, and the auxiliary fuel storage means is controlled by manual operation of the operating rod. 2. The auxiliary fuel supply mechanism of claim 1, wherein the fuel supply mechanism is moved along a straight path. 4. The operating means includes a temperature-sensing element that operates according to a temperature change of the internal combustion engine, and a device that converts the operation of the temperature-sensing element into a rocking motion of the auxiliary fuel retention means, and the operating means changes the temperature of the internal combustion engine. 2. The auxiliary fuel supply mechanism according to claim 1, wherein the auxiliary fuel storage means is moved along an arcuate path by the change. 5. A mechanism for supplying auxiliary fuel to an internal combustion engine to facilitate starting of the internal combustion engine, which includes a fuel supply mechanism and a carburetor provided with an intake port for taking in air, the mechanism having an air intake port; a housing defining a chamber communicating with the suction port; and a porous hole supported within the chamber so as to be displaceable between a position opposite to and close to the suction port and a position remote from the suction port. an auxiliary fuel retention means made of a solid material; a device for feeding fuel in a fuel tank to the auxiliary fuel retention means; and an operating means for moving the auxiliary fuel retention means to the adjacent position and to the remote position. , an auxiliary fuel for an internal combustion engine, comprising a recess formed in the housing to receive fuel falling from the auxiliary fuel retention means, and a return pipe for returning fuel accumulated in the recess to the fuel tank. supply mechanism. 6. According to claim 5, the recess is provided at a position corresponding to the remote position of the auxiliary fuel storage means to receive fuel falling from the auxiliary fuel storage means located at the remote position. Auxiliary fuel supply mechanism as described. 7. The housing is provided with a check valve in the recess for preventing backflow of fuel from the fuel tank toward the housing.
Auxiliary fuel supply mechanism as described in Section.