JPS61175258A - Engine equipped with diaphragm type carburetor - Google Patents

Abstract

PURPOSE:To improve starting performance by connecting a pressurizing pump which is mechanically interlocked with the recoiling device of a small-sized engine with said recoiling apparatus and connecting a negative-pressure generating device between a discharge-port side and a fuel tank and introducing the negative pressure into the metering chamber of a diaphragm type carburetor. CONSTITUTION:On the start of an engine 27, a handle 31 is pulled, and cranking is carried-out through a recoiling device 30, and at the same time, a pressurizing pump 33 is operated through a rod 35 by a cam shaft 34, and the fuel in a fuel tank 1 is supplied into the inflow port 7 of a carburetor 2 through a fuel pipe 9. Said fuel is introduced into the fuel chamber 61 of a fuel pump 50 by opening a check valve 47, and further reaches a fuel passage 60 by opening a check valve 48, while reaches a negative-pressure generator 65 from an outlet 70 through a pipe 51. The negative pressure generated in the fuel injection from a nozzle 78 acts into a metering chamber 16 through a check valve 76, and a diaphragm 11 is shifted upwardly, and an inflow valve 10 is opened through a lever 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine with a tire flam type carburetor used in a portable working machine.

[Prior Art] Engines whose working position changes, such as chainsaws and brush cutters, are equipped with a diaphragm type carburetor. This type of diaphragm type carburetor includes a diaphragm for dividing a metering chamber communicating with a fuel nozzle, a fuel pump driven by the operating pressure of the engine,
and an inflow valve that introduces fuel pumped from the fuel tank by the fuel pump into the metering chamber.

In normal operation, when fuel in the metering chamber is drawn into the engine through the fuel nozzle, the inlet valve opens due to the negative intake pressure acting on the diaphragm, and fuel is intermittently replenished from the fuel pump. Therefore, while the engine is operating, a predetermined amount of fuel is retained in the metering chamber regardless of its position, and the appropriate amount of fuel I'i is maintained depending on the engine operating condition.
I quantity is supplied to the engine.

However, when starting the engine, it is often the case that sufficient fuel is not reserved in the metering chamber in I, and this causes the engine to start in a rotational manner. For example, with a chainsaw, when the felling work is finished, the engine is stopped,
Tsurudori restarts the engine after moving to the next work area. When the engine is stopped for just a few minutes, the fuel in the fuel nozzle and the metering chamber that communicates with it evaporates due to heat from the engine body, atmospheric heat, and radiant heat from sunlight, and the metering chamber is filled with fuel scum. Even if the engine is still at warm-up temperature, the mixture becomes too lean due to the fuel gas, making it difficult to restart the engine. In addition, even if the engine starts, the low-speed fuel nozzle and metering chamber are not filled with fuel, which may cause a temporary fuel shortage, resulting in the engine stopping or 111
A first gear failure occurs, making it difficult to maintain smooth operation.

Furthermore, in order to reduce the number of small items on portable work equipment, the fuel tank has been made relatively small, so you won't notice when the fuel tank is empty. When refueling the engine, the engine cannot be started because not only the fuel pipe connecting the fuel tank and the carburetor but also the metering chamber of the carburetor are not filled with fuel.

To solve this problem, it is necessary to remove the fuel gas from the carburetor, or to replenish the carburetor with fuel immediately when starting the engine, or to inject fuel into the air passage. Ru.

One way to meet this demand is to provide a manual pump between the fuel tank and the metering chamber, as disclosed in U.S. Pat. No. 3,371,658.
Before starting the engine, use this manual pump to replenish fuel from the fuel tank to the metering chamber, then crank the engine after the engine starts -C! l'IJ! Some suggestions have been made. However, this is cumbersome to operate and also requires
If one pump is operated too many times, it will cause problems such as the diaphragm installed in the carburetor or the type fuel 1'1 pump.
Because the operating pressure (discharge pressure) is high, there is a risk that the suction valve will be forced open and excess fuel will be supplied to the metering chamber.
Due to this, the repulsive force in the remaking chamber becomes abnormally high, and excess fuel overflows into the intake passage, causing the engine to start 11i.
Jl student lowered 1! I am indebted to you.

[46 Problems to be Solved by the Invention] The purpose of the present invention is to forcibly remove the air and fuel gas in the metering chamber of the carburetor using a negative pressure generating device such as a pressurizing pump, and To provide an engine with a diaphragm type carburetor in which fuel in a fuel tank is replenished into a metering chamber and this function is automatically achieved by a recoil operation performed after an engine starting operation.

Means for Solving Problems 1 In order to achieve the above object, the configuration of the present invention is to connect a pressurizing pump mechanically interlocked with the recoil device of the engine, and to connect the pressurizing pump to the discharge port side of the pressurizing pump. A negative pressure generator is connected between the fuel tank and the fuel tank, and the negative pressure port of the negative pressure generator and the metering chamber of the dycephram carburetor are connected to each other.

[Operation] When the handle 31 is pulled upward to start the J resin 2f, the J
:The rod 35 of the pressurizing pump 33 is reciprocated, and by the pump action of the diaphragm 36, the fuel in the fuel tank 1 is sent to the carburetor 2 through the fuel pipes 9a, 9, and then through the fuel pump 50 to the outlet lower 0. and flows to the passage 60. The air and fuel gas in the metering chamber 16 are sucked into the fuel tank 1 by the negative pressure generated by the flow of fuel from the output lower 0 through the negative pressure generator 65 to the fuel tank 1 .

As a result, the repulsive force in the metering chamber 16 decreases, the inflow valve 10 opens, and fuel flows from the passage 60 into the metering chamber 16t.
＼Since the fuel is refilled, it is possible to start the engine.

[Examples of the Invention] The present invention will be described based on Examples. As shown in FIG.
A cleaner 28 and a diaphragm-type carburetor-equipped flap 29 are attached. The fuel tank 1 is located at the lower end of the engine 27, that is, below the crank chamber (=t
j) Run. The fuel tank 1 is supplied with fuel through an inlet closed by a cap 44. A filter 8 is housed inside the fuel tank 1 , and a fuel pipe 9 connected to the filter 8 is connected to an inflow lower of the carburetor 2 .

A recoil device 30 is connected to the end of the crankshaft of the engine 27 via a known one-way clutch. Konori T1
The rope device 30 has a rope wrapped around a boob, and a handle 31 is connected to the end of the rope. When the rope is pulled around the handle 31 against a spring, the crankshaft is rotated via a one-way clutch. It's getting wet.

According to the present invention, the camshaft 34 is formed integrally with the shaft of the pulley of the recoil device 30, and is arranged coaxially with the crankshaft of the engine 27. Roller 4 that engages with camshaft 34
3 is axially supported by the rod 35 of the +JI pressure pump 33.

The housing 52 of the pressurizing pump 33 is integrated with the housing 45 of the recoil device 30, and an atmospheric chamber and a pump chamber are partitioned by the dycephram 36. A spring 37 housed in the pump chamber then biases the rod 35, which is coupled to the diaphragm 36 and slidably supported by the housing 52, upward. A pump chamber of the pressurizing pump 33 is provided with a suction valve 39 and a discharge valve 38, and the suction valve 39 is connected to the filter 8 inside the fuel tank 1 via a fuel pipe 9a. The discharge valve 38 is connected to the inflow lower part of the carburetor 2 via the fuel pipe 9.

The carburetor 2 is equipped with a die A7 flamm type fuel pump 50 (Fig. 2) that is driven based on the pulsating pressure of the engine, and the lower outlet 0 connected to the discharge port is connected to a pipe 51. It is connected to the combustion fuel tank 1 via the negative 1 generator 65 and the pipe 50.

As shown in FIG.
are connected, while the diaphragm 11 is sandwiched between the lower wall and the
1 bar 15 is combined. The cover 4 has a pulsating pressure introduction port 5.
is connected to the crank chamber of the two-recycle engine, and this pulsating pressure acts on the diaphragm 6 constituting the fuel pump 50. A passage leading to the combustion chamber 61 defined by the diaphragm 6 is connected to the inflow lower via the check valve 47. Also, fuel to 6
1 is connected to the check valve 48, the passage 160, and the inflow valve 1.
0 is connected to the metering room 16 with red.

The diaphragm 11 that partitions the metering chamber 16 has its peripheral edge held between the main body 3 and the cover 15, and the chamber between the cover 15 and the diaphragm 11 is opened to the atmosphere through the atmosphere port 62. A needle-type inflow valve 10 is disposed at the end of the passage 60 and is opened and closed by a lever 13. That is, one end of the lever 13, which is rotatably supported on the wall of the metering chamber 16 with a support shaft 12, is engaged with the end of the inflow valve 10 by the force of the spring 14. The other end of the lever 13 is brought into contact with a protrusion connected to the approximate center of the die A2 flamm 11. The metering chamber 16 is connected to the high speed fuel injection port 24 via a check valve 26 and a high speed fuel cut amount button valve 25. Further, the metering chamber 16 is connected to the low-speed fuel injection port 21 via a check valve 23 and a low-speed fuel metering needle valve 22 .

The main body 3 is provided with a passage 60 communicating with the discharge port side of the fuel pump 50 and an outlet lower 0, and the outlet lower 0 is connected to the hero 1 of a negative pressure generator @65 via a pipe 51. The lower outlet 2 of the negative pressure generator 65 is connected to the fuel tank 1 via a pipe 80. Further, a suction port 40 is provided in the metering chamber 16, and an inlet 63 of a negative pressure generator @65 is connected to this via a pipe. The negative pressure generator 65 has a cylindrical housing 7
An output lower 2 is provided at one end of the pond 4, while a closing body 67 having an input lower 1 is fitted and supported at the end of the pond.

This closing body 67 constitutes a reverse well valve that is engaged with a spring 68 and a reball 66 at the inner end of the inlet lower 1, and a nozzle extending toward the outlet lower 2 on the side opposite to the inlet lower 1. 7
8 is supported. A negative pressure of 1 kl 69 is provided on the peripheral wall of the housing 74, and a check valve 76 is provided between the negative pressure port 69 and the inlet 63 to close the inlet 6a by a spring 75.
will be provided.

Next, the operation of the tire flam type carburetor engine according to the present invention will be explained. 7>I IEtE pump 3
When the rod 35 of No. 3 is pushed up by the force of the spring 37, the suction valve 39 opens and the fuel in the fuel tank 1 passes through the filter 8, the fuel pipe 9a, and the suction valve 39, and is added to the cylinder T7'33. is sucked into the pump chamber of the rod 3.
5 or camshaft 34: When pressed, the discharge valve 38
When the valve is opened, the fuel in the pump chamber is sent through the fuel pipe 9 from the inflow lower part to the inside of the carburetor 2. In this way, the fuel II that is intermittently pumped into the carburetor 2 enters the fuel chamber 61 of the fuel pump 50 through the valve 47 in reverse 1 in FIG. 2, and roughly pushes the check valve 48. It opens and flows into the fuel passage 60, but
With this fuel pressure, it is possible to open the inlet valve 10, after all,
Fuel enters the inlet lower 1 of the negative pressure generator 65 through the outlet lower 0 pipe 51, and the spring 68 connects the pole 66 constituting the check valve.
The fuel is pushed back against the force of , flows out from the nozzle 78 to the outlet lower 2 , and is returned to the fuel tanker 1 through the pipe 80 .

Negative pressure is generated in the negative pressure port 69 due to the throttling effect of the nozzle 78, and the check valve 76 opens against the force of the spring 75, allowing air and fuel gas in the metering chamber 16 to flow from the suction port 40 to the inlet 63 and The fuel flows into the housing 74 through the negative pressure port 69 and is then discharged from the lower 2 together with the fuel from the nozzle 78.
The fuel is discharged from the fuel tank 1 through a pipe 80.

When the air and fuel gas in the metering chamber 1G are discharged into the fuel tank 1, the pressure in the metering ¥16 decreases, the diaphragm 11 is pushed up by the atmospheric pressure, and the lever 13 moves in the opposite l18i1 direction around the support shaft 12. Since the inflow valve 10 is opened, the fuel 31 in the passage 60 is refilled into the metering chamber 16.

In this way, the air and fuel gas in the metering chamber 16 are discharged to the fuel tank 1, and when the metering chamber 16 is filled with fuel from the combustion tank 1 by the pressurizing pump 33, the intake negative pressure of the bench stiffener 17 is increased. Reverse 1 to valve 2
3 is opened and the fuel in the metering chamber 16 is slowly twisted n i
t Pass through M1 valve 22, low speed twisting 13+ 11jli port 2
1 into the intake passage 18, mixed with air, and supplied to the engine 27, making it possible to start the engine.

On the other hand, when the metering chamber 16 is filled with fuel, the diaphragm 11 is pushed down (1), and this diaphragm 11
The lever 13 is rotated by the spring 14 in the direction h1 about the support shaft 12 in response to the expansion of the inflow valve 10 into the passage 6.
0 to close the passageway 60. In this way, excess fuel is prevented from being pumped into the making chamber 16.

Conversely, when the fuel in the metering chamber 16 becomes low and the pressure decreases, the lever 13 is pushed up together with the diaphragm 11 by atmospheric pressure, and the inflow valve 10 is opened.

By the way, it is common for small engines such as chainsaws to be operated at full load, and the carburetor itself is exposed to quite high temperatures due to engine exhaust heat, causing the metering chamber 16 to
fuel is also more easily vaporized. Therefore, once the engine is stopped, the fuel in the metering chamber 16 flows out to the low-speed fuel nozzle 21 through the low-speed fuel metering needle valve 22 due to the internal pressure of the metering chamber 16, and stagnates inside the intake passage 18, causing the fuel concentration becomes abnormally high, and the fuel inside the metering chamber 16 becomes insufficient. If you restart the engine in this condition, a mixture with a high fuel concentration will be sucked into the cylinder, making it impossible to achieve good combustion.In addition, since there is insufficient fuel in the metering chamber 16, the low-speed fuel metering valve will 22 and the low-speed fuel nozzle 21.

As a result, the engine runs out of fuel and stops.

[Effects of the Invention] However, since the present invention is configured as described above, at the same time as the engine is cranked by the recoil operation, the fuel in the fuel tank 1 is transferred to the pressurizing pump 33 and the fuel in the fuel tank 1 is transferred to the fuel pump of the carburetor 2. 50, passes through the negative pressure generation device surface 65 from the outlet lower 0, and is returned to the fuel tank 1. The negative pressure generated in the negative pressure generation device 65 causes the metering chamber 1 to
6 are discharged into the fuel tank 1, the inflow valve 10, which cannot be opened by the fuel pressure from the pressurizing pump 33, opens as the pressure in the making chamber 16 decreases. Then, the pressure pump 33 outputs the lower 0 and the passage 60.
The fuel that was being sent to the metering chamber 16 encounters the throttle resistance of the nozzle 78 and is preferentially supplied to the metering chamber 16 from the passage 60, so that the metering chamber 16 is immediately filled with fuel 1, improving the startability of the engine. , stable continuous operation can be obtained even after startup. When the metering chamber 16 is filled with fuel,
Due to the action of the inflow valve 10, excess fuel flows into the metering chamber 1.
Since the fuel is prevented from flowing into the engine, an optimum amount of fuel is supplied to the engine, and a smooth and quick engine start is achieved.

Then, the pressurizing pump 33 is operated in conjunction with engine cranking due to the recoil operation, so the pump operation before the recoil operation is ineffective, unlike a conventional manual pump.
Easy to operate and reliable operation. Since the mounting position of the pressure pump 33 is close to the fuel tank 1, which is away from the high temperature part of the engine, there is little increase in humidity and less fuel gas is generated inside the pressure pump 33.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of an engine with a diaphragm type carburetor according to the present invention, and FIG. 2 is a side sectional view of the same diaphragm type carburetor. 1: Fuel tank 2: Diaphragm type carburetor 16: Metering chamber 21: Low-speed fuel mouth 24: High-speed fuel nozzle 27: Engine 30: Recoil equipment H31: Handle 33: Pressure pump 34: Camshaft 35: Port 37: Spring 43: N-RA 50: Fuel pump 52
:Housing 61:Fuel chamber 65:Negative pressure generator 6
9: Negative pressure port 78: Nozzle

Claims (1)

[Claims] A pressurizing pump mechanically interlocked with the recoil device of the engine is connected, a negative pressure generating device is connected between the discharge port side of the pressurizing pump and the fuel tank, and a negative pressure generating device is connected between the discharge port side of the pressurizing pump and the fuel tank. An engine with a diaphragm type carburetor, characterized in that a pressure port and a metering chamber of the diaphragm type carburetor are connected to each other.