JPS59556A - Carburetor with starter - Google Patents

Abstract

PURPOSE:To contrive not to allow an engine to stop even when an vehicle is started immediately after the starting of the engine at low temperatures, by permitting a thick mixed gas to be supplied from a slow system port when a starter is in use. CONSTITUTION:A plunger type starting valve 39 is formed with a large diameter guide 41 that is slidably guided within a guide bore 42 formed in a carburetor body 1. A second slow air bleed path 2 has an upstream side path 29a and a downstream side path 29b that are in communication via the guide bore 42. When the plunger type starting valve 39 is pulled out, the communication of the upstream side path 29a with the downstream side path 29b can be cut, and a second slow air bleed path 27 is closed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carburetor equipped with a starting device (pie starter).

Engines these days tend to be operated with the A/F set to a weaker setting in order to prevent exhaust gases. If the A/F is too thin, the starting performance will be poor, especially at low temperatures. For this reason, a method is adopted in which a starter device is attached to the carburetor and a rich air-fuel mixture is supplied from the starter device especially when starting at a low temperature to enrich the overall A/F.

However, when the engine is started at low temperatures using the starter described above and then immediately started without sufficient warm-up, the starter will supply a rich air-fuel mixture and the throttle valve will open. The air-fuel mixture is also supplied from the slow system nozzle, but the air-fuel mixture supplied from this slow system nozzle is originally A/F.
Since the air-fuel mixture is set to be relatively thin, the rich air-fuel mixture from the starter mentioned above mixes with the lean air-fuel mixture from the slow system nozzle, which increases the A/F required by the engine when starting at a low temperature.
It may be thinner than the engine, which may cause the engine to stall.

The present invention has been made based on these circumstances, and when a starter is used, the starter is also used from the slow system port to supply a richer air-fuel mixture compared to when the starter is used. It is an object of the present invention to provide a carburetor with a starting device that prevents the engine from stopping when the engine is started immediately after starting.

That is, in the present invention, the opening degree of the slow system air bleed passage is controlled in conjunction with the starting valve of the starting device, and when the starting fuel passage is opened by the starting valve to supply a rich mixture, When a υ starter is used, the above objective is achieved by reducing the amount of air in the slow system air bleed and supplying a rich mixture from the slow system as well.

An embodiment of the present invention will be described below based on the drawings.

In the figure, 1 is a carburetor main body, which forms an intake passage 2. A portion of a variable venturi constituted by a negative pressure responsive piston s7c is provided in the middle of the intake passage 2. The negative pressure responsive piston 3 is connected to a diaphragm 4, and an atmospheric chamber 5 and a negative chamber 6 are separated by the diaphragm 4.
It moves up and down based on the pressure difference. The atmospheric chamber 5 introduces outside air via the atmospheric air introduction path 7, and the negative pressure chamber 6 is connected to the piston 3.
Negative pressure is introduced into a portion of the venturi through a negative pressure introduction path 8 formed in the venturi.

When the negative pressure in a part of the venturi is large b, the piston 3 is raised and the jet needle 9 connected to the piston 3 is pulled up. Therefore, the opening of the main nozzle 10 is increased to increase the flow rate (Ml 11 i) and suck up fuel through the main jet 12 and supply the fuel from the main nozzle 10 to the intake passage 2. Note that an air bleed pipe 13 is provided between the main shell 12 and the main nozzle 100.
This air bleed pipe 13 has emulsion holes 14...
is formed. The emulsion holes 14... are connected to the main air shed 16 via the main air breech P passage 15.
It is familiar to

A throttle valve 20 is installed on the downstream side of a part of the variable venturi.
is provided so that the throttle valve 20t can be rotated via the valve shaft 21 by a throttle operator (not shown). By rotating the throttle valve 20, the opening area of the intake passage 2 is increased or decreased to control the amount of intake air. When the throttle valve 20 is at the minimum opening position, slow system ports 22 are opened in the intake passage 2 adjacent to the throttle valve 20. Further, an idle port 23 is opened on the downstream side of the slow system ports 22. This idle port 23 has an adjustment screw 24
The opening degree is adjusted by

The above slow port 22... and idle port 2
3 communicates with a slow system fuel supply passage 25 formed in the wall of the carburetor main body 1, and this slow system fuel supply passage 25
communicates with the float chamber 11VC via the slow jet 26.

A slow air bleed passage 27 is connected to the middle of the slow system fuel supply passage 25 .

The fuel supply passage 25 uses the air introduced from the slow air bleed passage 21 to suck up fuel from the slow jet 26 based on the principle of atomization. The slow air bleed passage 27 has a first slow air bleed passage 28 and a second slow air bleed passage 29' on the upstream side.
It is branched into. First slow air bleed passage 28
The second slow air bleed passage 29 is connected to the atmosphere through the slow air shed 30 of the diaphragm 4, and the second slow air bleed passage 29 is connected to the atmosphere chamber 5 divided by the diaphragm 4 through the starter device 35. It is opened via a slow air shed 31.

The starting device 35 is shown in FIG. That is, 36
is a start port opened downstream of the throttle valve 20 in the intake passage 2, and this start port 36 communicates with a starting fuel passage 37. Starting fuel passage 3
7 is connected to the float chamber 11 via a starter shell 38. The starting fuel passage 37 is opened and closed by a starting valve 39. The starting valve 39 is formed by, for example, a manual silanger valve, and when pushed in the direction of the arrow by an external operation, the starting fuel passage 37 is closed as shown by the imaginary line. The solid line state is the starting fuel passage 37.
40 is an aerosol lead hole for starting.

A large diameter guide portion 41 is formed in the plunger type starting valve 39 and is slidably guided within a hole 42 formed in the carburetor main body 1. The above-described second slow air bleed passage 29 is opened in the above-mentioned hole 421'C.

In the second slow air bleed passage 29, an upstream passage 29m and a downstream passage 29b are connected to each other via the guide hole 42. When the plunger type starting valve 39 is pulled out in the direction opposite to the arrow entry direction as shown by the solid line, K
The communication between the upstream passage 29h and the downstream passage 29b is cut off, and the second slow air bleed passage 27 is closed. Therefore, the large diameter f-id portion 4 of the plunger type starting valve 39
Reference numeral 1 constitutes the air bleed control mechanism of the present invention. The operation of the embodiment having such a configuration will be explained.

When starting the engine at low temperatures, the starting device 35 is used. That is, when the starting valve 3g is pulled out to the state shown by the solid line, the starting fuel passage 37 is opened at this point K, so that fuel is supplied from the starting port 36 and a rich air-fuel mixture is sent out. Further, when the starter valve s9 is pulled out in this way, the second slow air bleed passage 2g is not communicated with the atmosphere because the upstream side 29h and the downstream side 29b are closed.

When you start the engine in this state, the starting point is 3.
At the same time, fuel is supplied from the slow system port 22 and the idle port 23. Since the second slow air bleed passage 2g is closed as described above, the slow air bleed passage 27 connected to the slow system port 22 and the idle port 23 introduces outside air only from the first slow air bleed passage 28. . That is, the amount of slow air bleed is small, so a large amount of fuel is sucked up from the slow jet 26, and a rich air-fuel mixture is supplied from the slow system yJf-) 22 and the idle port 23. Therefore, a rich air-fuel mixture is sent out from all of the start port 36, slow system port 22, and idle port 23, so that the A/F becomes rich as a whole.

When starting immediately after such a start, the throttle valve 20 is opened and fuel is supplied from the main nozzle 10 with the A/F set to a low level, but the slow system port 22
Since a relatively rich air-fuel mixture is supplied from the idle port 23, the vF as a whole does not become lean, and there is no risk of causing engine malfunction.

In addition, if the vehicle does not start immediately after the above startup, the A/F
Since the temperature is relatively high, warm-up is performed quickly, and the warm-up operation time can be shortened.

When the engine becomes warm, the starter 35 is stopped. Then, the second slow air bleed passage 29 opens, and since air is sucked into the slow air bleed passage 27 from both the first slow air pull 1 passage 28 and the second slow air bleed passage 29, the aerosol lead Since the amount is large, the air-fuel mixture supplied from the slow system port 22 and the idling port 23 becomes dilute. As a result, harmful components in the exhaust gas are reduced.Although in the above embodiment, the starting device 35 was described as a manual type, the present invention may be an automatic type starting device, or a slow air bleed device. The mechanism for controlling the opening amount of the passage is not limited to the one directly using the starting valve 39;
Other valves linked to 9 may also be used.

As described in detail above, the present invention reduces the amount of slow yarn air bleed by regulating the opening degree of the slow yarn air bleed in response to the starting device when the starter is used at low temperature startup. The mixture supplied from the system port becomes richer. For this reason, the A/F as a whole is strong, and therefore, even if the vehicle starts immediately after starting, problems such as the engine stopping can be prevented. It's starting again lol
There is also the advantage that the warm-up time is shortened when the vehicle does not start immediately afterwards.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a cross-sectional view of a carburetor, and FIG. 2 is a sectional view of a carburetor. It is a sectional view along the line ■-■ shown together with the connection system of the second slow air bleed passage in Figure @1. DESCRIPTION OF SYMBOLS 1... Carburetor main body, 2... Intake passage, 3... Negative pressure responsive piston, 9... Jet needle, 10...
Main nozzle, 11... Float chamber, 2θ... Throttle valve, 22... Slow system port, 23... Idle port, 25... Slow system fuel A path,...? y・
... slow air bleed passage, 28... first slow air bleed passage, 29... second slow air bleed passage, 35... starting device, 36... start port, 37... Starting fuel passage, 39...Starting valve, 4
1... Large diameter guide portion % 42... Guide hole.

Claims (1)

[Claims] In a carburetor equipped with a starting device consisting of a starting fuel passage that supplies fuel from the foot chamber to the intake passage and a starting valve that opens and closes this starting fuel passage, a slow system air bleed passage responds to the starting valve. An air bleed control mechanism is provided to control the opening amount of the air bleed passage when the starting valve opens the starting fuel passage and supplies a rich mixture. A carburetor with a starting device characterized in that the slow system is also regulated to supply a rich mixture.