JPS6230297B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for controlling a mixture in a carburetor starting device, which automatically controls the amount and air-fuel ratio of the air-fuel mixture supplied to the engine when starting the engine, etc. The present invention relates to a control device, and in particular to a mixture control device in a carburetor starting device that controls a mixture supplied to an engine based on the temperature of the engine.

Conventional air-fuel mixture control devices use a thermosensitive body such as a bimetal that deforms depending on the engine temperature to displace the valve, and a needle valve at the tip of the valve controls the starting air-fuel mixture supplied from the carburetor. The main body of the valve controls the air to control the amount of air-fuel mixture and air-fuel ratio supplied to the engine, and the negative pressure at the time of engine complete explosion forces the valve to a specified position. There is one that is moved to a certain position to maintain the air-fuel mixture supplied to the engine at a constant value after a complete explosion.

Such a mixture control device can supply a mixture that satisfies the engine's demands from the time the engine starts until the time of complete explosion, but after the complete explosion, the temperature of the engine increases. Since a constant amount and air-fuel ratio of air-fuel mixture will be supplied regardless of the
There was a problem in that the air-fuel mixture could not be accurately controlled during warm-up until the engine temperature rose to a predetermined temperature.

The present invention aims to solve the problems with conventional air-fuel mixture control devices, and is designed to supply the proper air-fuel mixture to the engine from the time the engine starts, after complete explosion, to the completion of warm-up. An object of the present invention is to provide an air-fuel mixture control device in a starting device for a carburetor that can be used in a starting device for a carburetor.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIG. 1, an internal combustion engine 1 is equipped with a mixture control unit 3 at a location where the engine temperature can be sensed, for example at a cylinder head 2. As shown in FIG. The engine 1 is supplied with a mixture of air drawn through a main air cleaner 4 and fuel by a carburetor 5 through an intake pipe 6. The mixture control unit 3 is
It is connected to the sub air cleaner 7 by an air inflow pipe 8, and is also connected to the upstream side of the throttle valve in the intake path of the carburetor 5, that is, to the main air cleaner 4, by an air supply pipe 9. 5 is connected to the starting mixture supply section by the mixture inlet pipe 10, and is also connected to the throttle valve downstream side of the intake path of the carburetor 5, for example, the intake pipe 6, the mixture supply pipe 11, and the negative pressure action pipe 12. connected by. Furthermore,
The sub air cleaner 7 is connected to a starting air-fuel mixture supply section of the carburetor 5 via an air supply pipe 13.

The carburetor 5 and the air-fuel mixture control unit 3 will be explained with reference to FIG. It has a piston type throttle valve 16, and by operating an operating wire 17 attached to this throttle valve 16, the throttle valve 16 is slid up and down to adjust the opening of the intake passage 18 in the intake body 14. is now being carried out. A jet needle 19 is integrally provided with the throttle valve 16, and when the throttle valve 16 is raised to open the intake passage 18, the jet needle 19 is also raised.
Main air passage 21 from main air jet 20
With the air sucked through the float chamber 2
The fuel in the engine 2 is sucked out from the main fuel nozzle 24 through the main jet 23, and the mixture is sent to the engine 1 through the intake pipe 6. When the operating wire 17 is loosened, the throttle valve 16 is lowered by the elastic force of the return spring 25, and the intake passage 18 is closed to a predetermined idling opening degree.

A starting mixture supply section 2 is provided on the side wall of the carburetor 5.
6 is provided. Air is sucked into this supply section 26 through a starting air passage 27, and air is drawn into the float chamber 22 through a starting jet 28.
When starting the engine, these air and fuel are mixed in the emulsion tube 29, and the mixture is sucked out from the starting nozzle 30. There is.

Next, the mixture control unit 3 has a unit main body 33 provided with a bimetal chamber 31 on one side and a negative pressure chamber 32 on the other side. The unit main body 33 is provided with a starting air mixture inflow passage 34 and a starting air inflow passage 35, and these passages 34, 35 merge with each other at a merging portion 36. A first valve 37 whose one end protrudes into the bimetal chamber 31 is provided in the merging portion 36 .
is movable. The end of this valve 37 inside the bimetal chamber 31 is connected to the free end of a bimetal 38 which is a temperature sensing element provided inside this chamber 31.
They are connected by an adjustment screw 39 and a pressure spring 40. As shown in Figure 3, this bimetal 38
One end of the bimetal 38 is fixed to the unit body 33, and when the bimetal 38 deforms depending on the temperature of the engine 1, its free end is displaced and the valve 37 is moved.

The first valve 37 is configured such that the air inflow passage 35 is connected to the confluence part 3.
Air control unit 41 that increases or decreases the amount of opening opened to
, a first air-fuel mixture control section 42 that increases or decreases the opening amount of the outflow port in order to control the amount of air-fuel mixture flowing out from the merging section 36 , and a second needle-valve shaped control section 42 that further projects from this control section 32 . It has a mixture control section 43. Further, a second valve 44 is slidably provided opposite the first valve 37 in the axial direction.
At the end of the second valve 44 facing the first valve 37, there is provided a needle-like control section 43 of the first valve 37 for controlling the flow rate of the air-fuel mixture passing through the control section 43. A through hole 46 is formed to communicate between the inside of the recess 45 and the circumferential surface of the valve 44, and a seal member 47 is provided on the end surface of the through hole 46. It communicates with the supply passage 48 . The other end of the second valve 44 protrudes into the negative pressure chamber 32, and a diaphragm 49, which is a pressure sensitive body, and its stop member 50 are fixed to this end. This diaphragm 49 isolates the negative pressure chamber 32 from the atmospheric chamber 51 on the right side thereof in the figure. Further, a return spring 52 is provided between the unit body 33 and the valve 44, and constantly presses the valve 44 toward the retracted, inoperative position. As shown in FIG. 2, when the valve 44 is in the inoperative position, the first mixture control section 42 of the first valve 37 is located between the seal member 47 on the left end surface and the unit body 33. A passage 53 is formed through which the air-fuel mixture is directly guided to the air-fuel mixture supply passage 48 . When a negative pressure acts in the negative pressure chamber 32 and the valve 44 moves to the left and reaches the operating position, the passage 53 is closed as shown in FIG. Therefore, the valve 44 including the sealing member 47
The end face constitutes a first passage control section that opens and closes the passage 53. Furthermore, the recess 45 and the through hole 46 are
It constitutes a second passage control section that controls the air-fuel mixture that passes through the second control section 43 of the valve 37 and reaches the air-fuel mixture supply passage 48 .

An air supply passage 54 branches from the starting air inflow passage 35, and an air control unit 5 is connected to the branch part.
A third valve 55 having a diameter 5' is movably provided. One end of this valve 55 is connected to the bimetal chamber 31.
It protrudes inward, and its end is a bimetallic 38
It is connected to the free end of a bimetal 57 similar to that by an adjusting screw 57 and a pressure spring 58. This air supply passage 54 is connected by an air supply pipe 9 to a passage 59 communicating with the upstream side of the throttle valve 16 of the carburetor 5 , in particular with the main air passage 21 .
Air is introduced into the air inflow passage 35 from the sub air cleaner 7 by an air inflow pipe 8.

From the sub air cleaner 7, there is also air inflow passage 60 of the starting mixture supply section 26 of the carburetor 5.
Air is introduced by the air supply pipe 13, and the air-fuel mixture is sucked out from the starting nozzle 30 by the air. The mixture is led from the starting mixture supply passage 61 through the mixture inlet pipe 10 to the mixture inlet passage 34 of the control unit 3. The mixture supplied from the mixture supply passage 48 of the control unit 3 is guided from the intake pipe 6 to the engine 1 via the mixture supply pipe 11. The underpressure chamber 32 of the control unit 3 communicates with the intake pipe 6 and thus with the engine 1 by means of the underpressure pipe 12 .

FIG. 2 shows the engine when it is stopped and cold, and the free ends of the bimetals 38, 56 are displaced to the farthest left as shown. Therefore, both the first valve 37 and the third valve 55 are in the position moved to the leftmost position, and each air control section 41, 55' closes the air inflow passage 35 and the air supply passage 54, respectively. ing. In addition, the negative pressure chamber 32
Since no negative pressure is acting on the second valve 44, the second valve 44 is in the inoperative position, which is the most retracted position to the right.

When the engine 1 is started in this state, cranking negative pressure is generated, which flows from the sub air cleaner 7 through the air supply pipe 11 to the starting mixture supply section 26 of the carburetor 5.
Air is supplied to the starting nozzle 30, and the air-fuel mixture is sucked through the starting nozzle 30. This air-fuel mixture is led to the inflow passage 34 of the control unit 3 via the inflow pipe 10, and the valve 37
The first air-fuel mixture control section 42 measures the amount of air. The mixture that has passed through the control section 42 is guided to the mixture supply passage 48 through the passage 53, the recess 45, and the through hole 46 between the left end surface of the second valve 44 and the unit body 33, and is then led to the mixture supply passage 48. It is supplied to the engine 1 from the pipe 11 and the intake pipe 6 as a rich starting mixture.

When the negative pressure in the intake pipe 6 increases due to the complete explosion of the engine 1, the negative pressure acts on the negative pressure chamber 32 through the negative pressure action pipe 12, and the diaphragm 49 deforms against the pressing force of the return spring 52. As a result, the state shown in FIG. 4 is reached. Accordingly, the second valve 44 moves from the non-operating position shown in FIG. 2 to the operating position shown in FIG. 4, and the seal member 47 at its left end closes the passage 53. As a result, the air-fuel mixture further metered between the second control section 43 of the first valve 37 and the recess 45 of the second valve 44 passes through the recess 45 and the through hole 46 to the air-fuel mixture supply passage. 48, and is supplied to the engine 1 as a mixture after complete explosion. Therefore, this air-fuel mixture is smaller than that immediately after starting.

After the complete explosion of engine 1, the engine temperature rises. The bimetals 38, 56 are deformed accordingly, and their free ends are displaced to the right in the figure. This displacement causes both the first valve 37 and the third valve 55 to move to the right. As a result, the air control section 41 of the first valve 37 opens, and both the first and second air-fuel mixture control sections 42 and 43 move in the closing direction. As a result, the air supplied from the sub air cleaner 7 is transferred from the air inflow passage 35 to the air control unit 41.
After being metered by, it flows into the confluence section 36,
The starting mixture supplied from the carburetor 5 is appropriately diluted, and after this diluted mixture is further narrowed down by the first and second mixture control sections 42 and 43, the mixture supply passage 48, The mixture is supplied to the engine 1 as a warm-up mixture through the supply pipe 11 and the intake pipe 6. That is, during warm-up, the valve 37 moves according to the temperature of the engine, so that the air-fuel mixture from the carburetor 5 is transferred to the air control unit 4.
The air controlled by No. 1 joins, and the air-fuel ratio of the warm-up mixture is controlled appropriately, and the air controlled by No.
The air-fuel mixture control unit 43 controls the amount of air-fuel mixture supplied, and the air-fuel mixture necessary for warm-up operation is supplied to the engine.

Furthermore, by opening the air control section 55' of the third valve 55 in accordance with the rise in the temperature of the engine 1, the air flows from the sub-air cleaner 7 through the air inflow pipe 8 to the inflow passage 35.
The air flowing into the main air passage 21 is metered by the air control section 55' and divided into the air supply passage 54, and the controlled air is supplied to the main air passage 21 via the air supply pipe 9 and the passage 59. Therefore, when the engine 1 is at a low temperature, the amount of air supplied to the main air passage 21 is small and the air-fuel mixture supplied from the main fuel nozzle 24 is rich, but as the temperature of the engine 1 rises, the amount of air supplied to the main air passage 21 increases. As a result, the amount of air supplied from the main fuel nozzle 24 becomes leaner. In this way, an air-fuel mixture with an appropriate air-fuel ratio is supplied depending on the temperature of the engine 1.

When the temperature of the engine 1 further increases and warm-up is completed, the free ends of the bimetals 38 and 56 are displaced to the farthest right, and the valves 37 and 55 are also moved to the farthest right. In this state, the first mixture control section 42 of the valve 37 blocks the passage of the mixture flowing out from the merging section 36, so the supply of the mixture from the control unit 3 is stopped, and the engine 1 is operated by the main fuel nozzle. 24
Steady operation will be performed only with the air-fuel mixture supplied from the engine.

To explain the restart when the engine 1 is warm, at the time of restart, the bimetals 38 and 56 are displaced according to the temperature of the engine 1, and the valve 3
7 and 55 are also in corresponding positions. Figure 3 shows the state of the valves 37 and 44 at this time.
No. 7 air control section 41 is appropriately opened, and first air-fuel mixture control section 42 is appropriately closed. Therefore, the starting air-fuel mixture supplied from the carburetor 5 is appropriately diluted by the air flowing in from the air inflow passage 35 via the air control section 41, and the starting air-fuel mixture is diluted appropriately by the air flowing in from the air inflow passage 35 through the air control section 41.
After being measured at , the mixture is sent from the mixture supply passage 48 to the engine 1 via the supply pipe 11 as a starting mixture. Since this air-fuel mixture is thinner and smaller than the air-fuel mixture when the engine 1 is started in a cold state, it is possible to prevent the spark plug from getting wet when restarting, and the restart is performed extremely well. If the temperature of the engine 1 further increases after restarting, the bimetals 38 and 56 will be displaced accordingly to appropriately control the air-fuel mixture and air supplied from the control unit 3, as in the case described above. It is.

As described above, according to the present invention, at the time of starting,
The air-fuel ratio of the starting mixture is controlled by the air control section of the first valve according to the temperature state of the engine, and the supply amount of the mixture is controlled by the first mixture control section. Therefore, it is possible to supply the starting air-fuel mixture in the amount and air-fuel ratio most suitable for the conditions even in response to various starting requirements depending on the engine temperature, and it is possible to significantly improve starting performance. In addition, after the complete explosion, the first air-fuel mixture control section controls the amount of air-fuel mixture supplied during startup and the second air-fuel mixture control section during warm-up.
It is possible to always supply the air-fuel mixture in the amount and air-fuel ratio required by the engine in any operating state, such as starting, complete explosion, or warm-up.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing a fuel supply system of an internal combustion engine equipped with an air-fuel mixture control device according to the present invention;
3 is a sectional view taken along the line of FIG. 2, showing different operating states of the device; FIG. FIG. 7 is a cross-sectional view of the main parts of the same device showing a further different operating state. 1... Internal combustion engine, 3... Air mixture control unit,
5... Carburetor, 21... Main air passage, 34...
... Starting air mixture inflow passage, 35... Starting air inflow passage, 37... First valve, 38... Bimetal, 41... Air control section, 42... First air mixture control section, 43... ...Second mixture control section, 44...
Second valve, 45... recess, 46... through hole, 47
... Seal member, 48 ... Starting mixture supply passage, 49 ... Diaphragm, 53 ... Passage, 54
...Air supply passage, 55...Third valve, 56...
bimetal.

Claims (1)

[Scope of Claims] 1. A starting air-fuel mixture inflow passage and a starting air inflow passage that merge with each other are provided, and the opening ratio of these two passages is changed according to the temperature of the engine to control the amount and amount of the combined air-fuel mixture. In a starting device for a carburetor that controls the air-fuel ratio and guides the controlled air-fuel mixture to the engine from a starting air-fuel mixture supply passage; an air control section that controls the fuel ratio; a first air-fuel mixture control section that controls the outflow amount of the controlled air-fuel mixture; and a first air-fuel mixture control section that can further control the outflow amount of the air-fuel mixture controlled by the first control section. a first valve having a second mixture control section; a temperature sensing element that is displaced according to the temperature of the engine and moves the first valve; a first mixture control of the first valve; a first passage control part for opening and closing a passage through which the mixture passing through the starting mixture supply passage is directly guided to the starting mixture supply passage; and a second mixture control part for controlling the first valve when the passage is closed; a second passage control part that jointly controls the outflow amount of the mixture passing through the control part and communicates the controlled mixture to the starting mixture supply passage; Displaced by the negative pressure at the time of engine complete explosion, this second
A mixture control device in a starting device for a carburetor, comprising: a pressure sensitive body for moving a valve; 2 an air supply passage that branches from the air inflow passage and communicates with the main air passage of the carburetor; a third valve that controls the opening amount of this air supply passage; 3. The air-fuel mixture control device according to claim 1, further comprising: a temperature sensing element for moving the valve of No. 3;