JPH04191455A - Device for starting engine with diaphragm type carburetor - Google Patents

Abstract

PURPOSE:To improve the startability and the starting operation by providing a pressure pump to be driven at the only time that a recoil starter is pulled, and providing an auxiliary diaphragm for opening a fuel valve with the air pressure fed from a pressure pump. CONSTITUTION:When a recoil starter 38 is pulled to start an engine, a rod 36 of a pressure pump 31 is pushed by a rope 39, and a diaphragm 33 is moved to pressure-feed the air inside of the pump chamber 34 to a pressure chamber 27. An auxiliary diaphragm 25 is moved by this air pressure, and a metaling diaphragm 19 of a carburetor 1 is pushed up to open a fuel valve 20. A fuel pump 10 of the carburetor 1 is driven by cranking of the engine, and the fuel sucked from a fuel tank 15 is flowed into a diaphragm chamber 6 through an opening of the fuel valve 20, and is injected from a nozzle 5 to a suction passage 3. On the other hand, when the recoil starter 38 is returned, since the pressure of the pressure pump 31 is cancelled, the fuel valve 20 is closed to stop the injection of the fuel to the suction passage 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a starting device for an engine equipped with a diaphragm carburetor.

[Conventional technology]

Diaphragm carburetors, which are generally used for engines such as brush cutters and chainsaws, have good slope characteristics and are ideal for these engines, but the fuel in the diaphragm chamber of these carburetors is almost empty after the engine is stopped. Therefore, it is necessary to fill the diaphragm chamber with fuel before the next start.

Conventionally, therefore, a mechanism has been adopted in which a starter pump is attached to the carburetor and the starter pump is operated before starting the engine to introduce fuel into the diaphragm chamber.

(Utility Model Publication No. 51-43315, Japanese Unexamined Patent Publication No. 55-697
(Refer to Publication No. 48) Furthermore, although it is necessary to enrich the mixture concentration to start the engine, even if the diaphragm chamber is filled with fuel, the amount of fuel supplied from the nozzle is adjusted to match the operating conditions after starting. Therefore, in order to supply the desired rich mixture to the engine, it is necessary to further limit the amount of intake air by closing the choke valve.

[Problems with conventional technology]

In this way, in the conventional technology, when starting the engine, it is necessary to operate the starter pump and then perform the choke operation.
These operations were extremely troublesome.

SUMMARY OF THE INVENTION An object of the present invention is to provide an engine starting device equipped with a diaphragm carburetor that is easy to start and has good startability.

[Means for solving problems]

The present invention consists of a pressurizing pump that is pushed by a rope of the starter and pressurizes air when the recoil starter is pulled, and a pressurizing pump that moves in response to the pressurized air from the pressurizing pump and presses the metering diaphragm of the carburetor. It is characterized by being provided with an auxiliary diaphragm that opens the fuel valve.

[Effect]

When the recoil starter is pulled to start the engine, the recoil starter's rope pushes the pressure pump and pumps air. The auxiliary diaphragm moves in response to air pressure fed from this pressure pump, pushing up the metering diaphragm and opening the fuel valve. Further, the cranking of the engine drives the fuel pump of the carburetor, and the fuel sucked from the fuel tank flows into the diaphragm chamber through the opening of the fuel valve, and is ejected into the intake passage through the nozzle.

Furthermore, when the recoil starter returns, the pressure of the pressurizing pump is released, so the sub diaphragm moves downward, the fuel valve is closed, and the injection of fuel into the intake passage is stopped. Therefore, fuel is injected only when the recoil starter is pulled, that is, only during cranking of the engine. As a result, fuel intake into the engine and ignition are improved,
Engine startability is improved.

〔Example〕

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is an explanatory view of the starting device of the present invention, and FIG. 2 is an explanatory view of essential parts showing another embodiment of the starting device of the present invention.

Reference numeral 1 denotes a diaphragm type carburetor, and an intake passage 3 is provided through the body 2. The upstream side of this intake passage 3 is connected to an air cleaner (not shown), and the downstream side is connected to an intake port of an engine (not shown). ing. Also, this intake path 3
A throttle valve 4 for making the effective diameter of the intake passage 3 variable is disposed therein. A fuel nozzle 5 is opened in the intake passage wall below the throttle valve 4, and the other end of the fuel nozzle 5 is connected to a diaphragm chamber 6.

10 is a fuel pump driven by the operating pressure of the engine, and this fuel pump 10 has a pump diaphragm 11.
This is a conventionally well-known diaphragm pump consisting of a pair of check valves 12 and 13. By applying engine operating pressure to a pressure chamber 14 formed on one side of the pump diaphragm 11, the pump diaphragm 11
is vibrated to suck fuel from the fuel tank 15 through one check valve 12 into the pump chamber 17 formed on the other side of the pump diaphragm 11, and from the other check valve 13 through the fuel passage 18 into the diaphragm chamber 6. It is being pumped.

The diaphragm chamber 6 of the fuel passage 18 is connected to the metering diaphragm 19 in order to disconnect the passage 18, that is, to disconnect the communication between the fuel pump 10 and the diaphragm chamber 6 (operating fuel valve 20). A lever 22 having a support shaft 21 is disposed between the fuel valve 20 and the metering diaphragm 19.

The lever 22 has one side centered around the support shaft 21 that is connected to the fuel valve 20.
The other side is connected to the metering diaphragm 19. Therefore, when a strong negative intake pressure acts on the diaphragm chamber 6 through the fuel nozzle 5, the metering diaphragm 19 moves the fuel valve 2 through the lever 22 to introduce fuel into the diaphragm chamber 6.
0 is held in the open position of the fuel passage 18. Further, when the strong negative pressure in the diaphragm chamber 6 disappears due to the introduction of fuel into the diaphragm chamber 6, the fuel valve 20 causes the fuel to flow into the diaphragm chamber 6 by the biasing force of the compression spring 23 that engages the lever 22. The passageway 18 is blocked to prevent the introduction of.

A sub-diaphragm 25 is provided below the metering diaphragm 19, an atmospheric chamber 26 is formed above the sub-diaphragm 25, and a pressure chamber 27 is formed below. A rod 28 is attached to the auxiliary diaphragm 25 to push up the metering diaphragm 19 so as to protrude toward the atmospheric chamber 26 side, and a rod 28 is attached within the atmospheric chamber 26 to urge the auxiliary diaphragm 25 toward the pressure chamber 27 side. A spring 29 is provided.

Reference numeral 31 designates a pressure pump, in which a diaphragm 33 is stretched in a casing 32, a pump chamber 34 is formed on one side of the diaphragm 33, and an atmospheric chamber 35 is formed on the other side. A protruding rod 36 is attached, and an elastic spring 37 is disposed within the pump chamber 34 to constantly bias the diaphragm 33 in a direction in which the volume of the pump chamber 34 increases, and by pushing the rod 36, the pump It is configured so that the air within the chamber 34 is forced out. Further, the tip of the rod 36 protrudes and engages with a rope 39 of the recoil starter 38 so as to bend a part of the rope 39.
When pulled, the rod 36 is pushed by the rope 39, and the air in the pump chamber 34 is pumped out.

The pump chamber 34 is connected to the pressure chamber 27 by an air supply passage 41. Therefore, when the recoil starter 38 is pulled, that is, when the engine is cranked, the air pumped from the pump chamber 34 flows into the pressure chamber 27, moves the sub diaphragm 25 upward, and pushes up the metering diaphragm 19. Open the fuel valve 20.

On the other hand, when the recoil starter 38 returns, that is, when the engine is not cranked, the rod 36
The pressure of
It returns to its normal position by the action of As a result, the pressure chamber 2
7 disappears, the sub diaphragm 25 descends, and the fuel valve 2
0 is closed.

A temperature-sensitive valve 43 is provided on the air supply passage 41, which opens when the engine temperature is high and opens the passage 41 to the atmosphere through a leak hole 42. Therefore, when the engine temperature is high, a portion of the pressurized air is released to the atmosphere, reducing the amount of upward movement and pushing up time of the auxiliary diaphragm 25, and reducing the amount of fuel injected into the intake passage 3. Although it is not particularly necessary to provide this temperature-sensitive valve 43, it is desirable to provide it because starting performance can be further improved under a wide range of temperature conditions. Further, this temperature-sensitive valve 43 may be provided in the pressure chamber 27 or the pump chamber 34.

45 is a leak hole that communicates the pressure chamber 27 with the atmosphere. Although it is not particularly necessary to provide this leak hole 45, this leak hole 45 is provided for adjustment when the sub diaphragm 25 returns slowly or does not return when the recoil starter 38 returns.

Next, the operation of the above embodiment will be explained.

When the recoil starter 38 is pulled to start the engine, the rod 36 of the pressure pump 31 is pushed by the rope 39, the diaphragm 33 is moved, and the air in the pump chamber 34 is forced into the pressure chamber 27. This air pressure moves the auxiliary diaphragm 25, pushes up the metering diaphragm 19 of the carburetor, and opens the fuel valve 20. Further, the fuel pump 10 of the carburetor is driven by engine cranking, and the fuel sucked out from the fuel tank 15 flows into the diaphragm chamber 6 through the opening of the fuel valve 20, and flows from the nozzle 5 to the intake passage 3.
gushes out. Furthermore, when the recoil starter 38 returns, the pressure of the pressure pump 31 is released, so the fuel valve 2
0 is closed, and the injection of fuel into the intake passage 3 is stopped. Therefore, fuel is injected only when the recoil starter 38 is pulled, that is, only during cranking of the engine. As a result, the intake of fuel into the engine and ignition become better, and the startability of the engine becomes better.

Further, when the engine is warmed up, the temperature-sensitive valve 43 opens,
The air sent from the pressure pump 31 is leaked to the atmosphere through the leak hole 42 to reduce the amount of air fed to the pressure chamber 27 and the retention time of the air, thereby increasing the amount of push-up and push-up of the metering diaphragm 19. Decrease time. As a result, the amount of fuel injected into the intake passage 3 is reduced, which improves starting during warm-up.

Furthermore, when the internal pressure of the fuel tank 15 is high, excessive fuel is injected into the intake passage 3 when the fuel valve 20 is opened, so as shown in FIG. 33, and by connecting this atmospheric chamber 35 and the upper air layer of the fuel tank 15 through a pipe 48, the diaphragm 33 of the pressurizing pump 31 is connected to the pump chamber 34 according to the internal pressure of the fuel tank 15. By moving it in the direction where the volume decreases, it is possible to reduce the amount of air forced to be fed when the recoil starter 38 is operated, thereby reducing the opening of the fuel valve 20 of the carburetor and reducing the amount of fuel injected into the intake path 3. can.

〔Effect of the invention〕

As detailed above, according to the present invention, a pressurizing pump is provided that is driven only when the recoil starter is pulled, and the air pressure sent from the pressurizing pump pushes up the metering diaphragm and opens the fuel valve. By providing an auxiliary diaphragm that opens, the fuel valve is opened only when the recoil starter is pulled, that is, during engine cranking, and the fuel supplied from the fuel pump is spouted into the intake passage, ensuring that the fuel is The spark plug is ignited inside the engine, and the spark plug is no longer fogged, resulting in good starting performance. Furthermore, unburned gas is no longer released into the atmosphere.

Furthermore, according to the present invention, the engine can be started by simply pulling the recoil starter, making the starting operation extremely easy.

[Brief explanation of the drawing]

FIG. 1 is an explanatory view of the starting device of the present invention, and FIG. 2 is an explanatory view of essential parts showing another embodiment of the starting device of the present invention. 1...Diaphragm type carburetor, 3...Intake path, 19
...Metering diaphragm, 20...Fuel valve, 2
5... Sub-diaphragm, 27... Pressure chamber, 31...
・Pressure pump, 38... Recoil starter, 39...
·rope. Patent applicant Makoto Bando, representative of TK Vaporizer Co., Ltd.

Claims (1)

[Claims] When the recoil starter is pulled, a pressure pump is pushed by the rope of the starter to pump air, and the air moves under pressure from the pressure pump, pushing up the metering diaphragm of the carburetor and opening the fuel valve. A starting device for an engine equipped with a diaphragm type carburetor, characterized in that it is provided with an auxiliary diaphragm that opens.