JPH03151552A - Amount of fuel increasing device of carburetor - Google Patents

Abstract

PURPOSE:To prevent mixture from becoming lean when an engine is operated at low speed with a throttle valve wide open by providing an amount of fuel increasing pump within an amount of fuel increasing passage which supplies fuel from inside a fuel tank to the air intake of a carburetor, and providing the amount of fuel increasing passage with a control valve for controlling communication between the amount of fuel increasing passage and a return passage. CONSTITUTION:A throttle valve 9 to be manually controlled is slidably provided within the sliding valve guide tube 3 of a carburetor main body 1 through which an air intake 2 is bored. A needle 13 for controlling the area of a passage of a jet 14 communicated with a float chamber 5 is mounted to the throttle valve 9. Fuel is supplied from a fuel pump P to the float chamber 5 via a fuel inflow passage 17 and a valve seat 6. An amount of fuel increasing passage 21 for supplying fuel increased by an amount of fuel increasing pump 20 to a control jet 34 disposed opposite to the air intake 2 is provided and a control passage 23 which opens the amount of fuel increasing passage 21 and shuts out communication between the passage 21 and a return passage 22 when the throttle valve 9 is open for more than a fixed degree and the rotating speed of an engine is within a fixed range is interposed in the passage 21.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a carburetor that controls the amount and concentration of air-fuel mixture supplied to an engine, and particularly relates to a carburetor that controls the amount and concentration of air-fuel mixture supplied to an engine. This relates to a fuel increase device for a carburetor that mechanically controls opening and closing using a throttle valve operated by a 7-cell wire.

[Conventional technology]

There are two main types of carburetors that mechanically control the opening and closing of the effective opening area of the intake tract using a throttle valve operated by an accelerator wire.

The first is one in which a valve shaft is rotatably supported by the carburetor body across an intake path that passes through the carburetor body, and a disc-shaped butterfly valve is attached to the valve shaft. The valve shaft is rotated by operating the accelerator wire, and the butterfly valve controls the opening and closing of the effective opening area of the intake tract. (It is usually called a butterfly type carburetor and is shown in, for example, Japanese Utility Model Publication No. 50-43617.) The second method is to install a sliding valve guide cylinder above the middle part of the intake passage that passes through the carburetor body. A cylindrical or rectangular sliding throttle valve is slidably arranged within the sliding valve guide cylinder, and the sliding throttle valve can be moved within the sliding valve guide cylinder by operating an accelerator wire. The opening and closing of the effective opening area of the intake passage is controlled by a sliding throttle valve. (It is usually called a sliding throttle valve type carburetor, for example,
It is shown in 2-54671 and the like. ) As mentioned above. The first method is to mechanically open and close the effective opening area of the intake tract using a throttle valve. According to the second vaporizer, it has the following problems.

First, when the throttle valve is opened to a high opening and the rotation speed of the Ia valve is low (high opening and low speed operation), the air flow velocity flowing through the intake tract becomes low, and each fuel jet that opens into the intake tract The negative airway pressure applied to the hole is weakened. (approaching atmospheric pressure) According to this K, it becomes difficult to suck out sufficient fuel from each fuel injection hole into the intake passage, and this high opening and low speed is not desirable as it causes dilution of the air-fuel mixture. The phenomenon of air-fuel mixture dilution during operation becomes more pronounced as the diameter of the intake duct is increased in order to improve the output of the engine.

As a conventional technology aimed at solving this problem, an air control valve is placed upstream of the sliding throttle valve, and during high opening and low speed operation, the output of the throttle valve opening sensor and the engine rotation speed sensor are A technique is known that controls an air control valve in the closing direction depending on the output. (This is shown in Utility Model Application Nos. 60 to 70761.) Second, in order to rapidly increase the rotation from a low opening state, the throttle valve is raised rapidly, as in the case of engine fitting operation. Considering the sudden acceleration operation of an engine that opens to the opening, an increased amount of air is immediately supplied to the engine due to the sudden opening of the throttle valve, but the supply of fuel is temporarily delayed due to air inertia. As a result, the mixture becomes diluted, which is not preferable.

This phenomenon of air-fuel mixture dilution becomes more pronounced as the diameter of the air intake passage increases.

As a conventional technique aimed at solving this problem, a diaphragm is used to divide the housing into a pump chamber and an atmospheric chamber, and the pump chamber is equipped with a suction-side reverse valve, which is connected to the float chamber. A check valve on the discharge side is disposed inside the acceleration fuel inlet passage, and an acceleration fuel discharge passage connected to the intake passage are opened, and this diaphragm is pressed toward the pump chamber side during the sudden opening operation of the throttle valve. There is a technique of a so-called acceleration pump device in which a pump chamber is pressurized and acceleration fuel stored in the pump chamber is injected and supplied into an intake passage through an acceleration fuel discharge passage. (
It is shown in Japanese Patent Publication No. 46-43050. ) [Problems to be Solved by the Invention] This conventional technology has the following problems.

First, according to the technology disclosed in Japanese Utility Model Application No. 60-70761, during high-opening, low-speed operation, the sliding throttle valve is kept open at a high opening, but the air control valve is controlled by the output signal from the control unit in the intake airway. is controlled in the closing direction to reduce the effective opening area of the intake tract upstream of the sliding throttle valve. According to this, the negative pressure in the intake tract including the sliding throttle valve on the engine side from the air control valve increases, and the needle jet as the main fuel system that opens into the intake tract on the engine side from the air control valve increases. The negative pressure applied to the opening of the intake tract is increased, which allows a larger amount of fuel to be sucked into the intake tract than with a needle jet, thereby preventing dilution of the air-fuel mixture. However, since the air control valve operates in the direction of closing the intake tract and reduces the effective opening area of the intake tract, the amount of air supplied to the engine decreases, which is not desirable in terms of improving engine output. .

Next, the technology disclosed in Japanese Patent Publication No. 46-43050 pressurizes the pump chamber by the sudden opening operation of the throttle valve, and injects the accelerating fuel stored in the pump chamber into the intake passage through the accelerating fuel discharge passage. Yes, but.

According to this, although a fixed amount of acceleration fuel can be supplied, it is difficult to set a long acceleration fuel injection time to be supplied from the acceleration pump device into the intake passage.

This is due to the fact that the diaphragm that pressurizes the pump chamber of the acceleration pump device is mechanically connected to the throttle valve. Selection of a diaphragm spring that is compressed inside the room and urges the diaphragm toward the atmospheric chamber.
Selection of passage diameters of the acceleration fuel intake passage and acceleration fuel discharge passage, selection of valve closing springs to press and bias the intake side check valve and discharge side check valve against each valve seat, etc. The work required a large amount of setup time, which hindered improvement in development efficiency.

Further, even if each of the above-mentioned factors is selected, there is a limit to how long the accelerated fuel injection time can be extended.

[Means to solve the problem]

The fuel increase device for a carburetor according to the present invention has been developed in view of the above-mentioned problems, and is designed to operate one engine at a high opening and low speed in a carburetor that mechanically controls opening and closing of the effective opening area of the intake passage using a throttle valve. It is an object of the present invention to provide a fuel increasing device that can suppress the dilution of the air-fuel mixture during engine speed and acceleration operation, and actively enrich the air-fuel mixture.

According to the fuel increasing device for a carburetor of the present invention, the carburetor mechanically opens and closes the effective opening area of the intake passage passing through the carburetor body using a throttle valve. , a fuel inflow path that is pressurized by a fuel pump and supplied to a valve seat opening in the float chamber of the carburetor; and a fuel increase pump that sucks fuel in the fuel tank through the suction path and discharges it through the discharge path. and a fuel increase passage, one end of which is connected to the discharge path of the fuel increase pump, and the other end connected to the intake path of the carburetor including the intake pipe; and a return passage that branches from the fuel increase passage and connects to the fuel tank: of the throttle valve. When the fuel increase passage is opened, the fuel increase passage and the return passage are connected to each other by a control signal from a control circuit that receives the output of the throttle valve opening sensor that detects the opening degree and the output of the rotation sensor that detects the engine rotation speed. and a control valve that connects the fuel increase passage and the return passage when the fuel increase passage is blocked; Within a certain rotational speed range, the control valve is operated by a control signal from the control circuit to open the fuel increase passage and cut off communication between the fuel increase passage and the return passage. Fuel that has been pressurized and fed to the fuel increase passage can be injected into the intake passage through the fuel increase passage.

On the other hand, when the opening of the throttle valve is above a certain degree and the engine speed is outside the certain rotational speed range, the control valve is operated by a control signal from the control circuit to close the fuel increase passage and close the fuel increase passage and the return passage. According to this, the injection supply of fuel from the fuel increase passage into the intake passage is suppressed, and the increase fuel that has flowed into the fuel increase passage is returned to the fuel tank via the return passage.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fuel increasing device for a carburetor according to the present invention will be described below with reference to FIG. Note that this embodiment is an embodiment of a sliding throttle valve type carburetor.

Reference numeral 1 designates a carburetor body in which an intake passage 2 passes through, and a sliding valve guide cylinder 3 is connected upward from a substantially middle portion of the intake passage 2, and is opposed to a lower concave portion IA of the carburetor body 1. A float basic body 4 is arranged, and a float chamber 5 is formed by the lower recess IA and the float basic body 4.

A valve seat 6 opens in the float chamber 5, and a float valve 7 is disposed corresponding to the valve seat 6 to open and close the valve seat 6, and this float valve 7 is further disposed within the float chamber 5. A driving force for opening and closing the valve seat 6 is applied by the float 8 .

A throttle valve 9 that controls opening and closing of the effective opening area of the intake passage 2 is movably disposed inside the sliding valve guide cylinder 3, and this throttle valve 9 is rotatably supported on the carburetor body 1. The operating shaft 12 is mechanically connected to the operating shaft O by a link 11, etc., and an operating lever 12 is integrally attached to the shaft end of the operating shaft that protrudes outside the carburetor body l. An accelerator wire (not shown) that is index-operated by the driver is attached to 12.

Therefore, when the driver operates the accelerator wire, the operating lever 12 and operating shaft 10 rotate, and this is transmitted to the throttle valve 9 via the link 11, so that the throttle valve 9 opens and closes the intake passage 2. become.

Further, a jet needle 13 is integrally attached to the bottom of the throttle valve 9.
is inserted into a needle jet 14 that opens into the intake passage 2.

The needle jet 14 is connected to the main jet [8 through the mixing nozzle 15, and the above-mentioned mixing nozzle 1
An annular acceleration well W is formed on the outer periphery of the float chamber 5, and the fuel in the float chamber 5 is stored in the acceleration well W. on the other hand,
The valve seat 6 is supplied with pressurized fuel stored in the fuel tank T via the fuel inlet passage 17, and the fuel in the fuel tank T is pressurized by the fuel pump P. The fuel is supplied to the fuel inflow path 17.

Therefore, when the liquid level in the float chamber 5 is lower than the set liquid level, the float valve 7 opens the valve seat 6 by the float 8, so that the valve seat 6 is
Fuel flows into the float chamber 5 through the float chamber 5, and when the liquid level in the float chamber 5 rises to a set constant level, the float valve 7 closes the valve seat 6 with the float 8, so that the fuel inflow path 17 from the float chamber 5 through the valve seat 6.
6 and above are conventionally known vaporizers in which the supply of fuel into the float chamber 5 is stopped, thereby making it possible to always form a constant liquid level in the float chamber 5.

Reference numeral 20 denotes a fuel increase pump that sucks in fuel from a fuel tank N that stores fuel inside, such as the fuel tank T or the float chamber 5, through the suction passage 20A, and pressurizes and discharges it from the discharge passage 20B; The pump type may be electric, mechanical, pulsation type, etc. This fuel increase pump 20 performs a pumping action while the engine is operating.

Reference numeral 21 denotes a fuel increase passage whose one end is connected to the discharge passage 20B of the fuel increase pump 21 and whose other end is connected to the intake pipe 2 or an intake pipe (not shown) that connects the intake passage 2 of the carburetor body 1 and the engine. It is.

22 is a return passage that branches off from the fuel increase passage 21 and continues to the fuel tank T. Reference numeral 23 designates a control valve that opens and closes the fuel increase passage 21 and the return passage 22 as described below, and its specific structure will be explained below.

That is, 24 is an increase valve seat provided in the fuel increase passage 21, and 25 is a return valve seat provided at the opening of the return passage 22 to the fuel increase passage 21. A return valve part 27 is arranged facing the return valve seat 25, and this increase valve part 2B
and the return valve part 27 are integrally formed to constitute a valve part V, and when the increase valve part 2B of this valve part V closes the increase valve seat 24, the return valve part 27 opens the return valve seat 24. On the other hand, when the filling valve section 2B opens the increasing valve seat 25, the return valve section 27 closes the return valve seat 25. Then, this valve part V is activated by energizing the fixed iron core 2 by energizing the solenoid 2.
9 and is integrally attached to the movable core 30 which separates from the fixed core 28 when the solenoid 2 is de-energized. (This control valve 23 does not have to be a solenoid valve, but can be appropriately selected as long as it has the function of electrically opening and closing the passage.)
31 is a throttle valve opening sensor that detects the opening of the throttle valve 9 with respect to the intake passage 2; 32 is a rotation sensor that detects the engine speed; the outputs of the throttle valve opening sensor 31 and the rotation sensor 32 are sent to the control circuit. 33, and a control signal for driving the control valve 23 is output from the control circuit 33 under predetermined conditions of the throttle valve opening degree and the engine rotation speed.

To give a specific example of the above-described conditions such as the throttle valve opening and the engine rotation speed under which the control signal for driving the control valve 23 is output from the control circuit 33, the opening of the throttle valve 9 is A control signal for driving is outputted from the control circuit 33 to the control valve 23 when the engine is opened by 3/4 or more and the engine speed is within the range of 20 ORPM to 500 ORPM. The condition range is clearly indicated by the shaded area in FIG. 2, but this condition range is appropriately set optimally during the setting work of the carburetor for the engine, and is not limited to the above conditions.

Next, we will discuss its effect.

First, as when operating the throttle valve 9 at a low or medium opening,
To explain this in an operating state where the opening degree is 3/4 or less, no matter how the engine speed changes, the throttle valve 9 does not open to a certain opening degree. A control signal for this is not output, so the control valve 23 is in an inoperative state, and the increase valve portion 28 of the valve portion V comes into contact with the increase valve seat 24 and closes the fuel increase passage 21.
On the other hand, the return valve portion 27 is separated from the return valve seat 25 and keeps the fuel increase passage 21 and the return passage 22 in communication. Therefore, the fuel in the fuel tank N is
The fuel is discharged from the suction passage 20A to the discharge passage 20B and fed into the fuel increase passage 21, but the increase valve portion 26 is connected to the increase valve seat 2.
4 is kept closed, the fuel fed into the fuel increase passage 21 is returned to the fuel tank T via the return passage 22, so the increased amount of fuel is supplied from the fuel increase passage 21 to the intake passage 2. Never.

In addition, during high opening operation in which the throttle valve 9 is opened further than during the low and medium opening operation, and the load applied to the engine is small or medium load, that is, high opening high speed, high opening medium speed, and operation. At times, the engine speed increases sufficiently due to the throttle valve 9 being opened to a high opening and the load being relatively small, and the engine speed is maintained at 5000 PPM or more. Rotation speed range set to 200
Since it is outside the range of 0PPM to 500ORPM, no control signal for driving is outputted from the control circuit 33 to the control valve 23.

Therefore, as described above, the control valve 23 keeps the fuel increase passage 21 closed. That is, in the normal operating state of the 1111, the throttle valve 9 is operated at a low opening, medium opening, and the throttle valve 9 is operated at a high opening, medium speed, and high opening, and sometimes the fuel increase passage 21 is kept closed, and since the fuel increase passage 21 is in communication with the return passage 22, additional fuel is not supplied from the fuel increase passage 21 to the intake passage 2, and the main fuel normally contained in the carburetor is not supplied to the intake passage 2. Main jet 16 as a system, needle jet 14,
Jet needle 13. Alternatively, fuel may be sucked out into the intake passage z from a bypass hole and a pilot outlet hole (both not shown) as a low-speed fuel system to ensure satisfactory engine operation.

The fuel increasing device for a carburetor according to the present invention has the following special effects.

First, the throttle valve 9 is opened to a high opening degree, and the engine speed is relatively low when the throttle valve 9 is operated at a high opening degree and at a low speed. Such a situation is a state in which the throttle valve 9 is opened to a high opening degree and a high load is applied to the engine, such as when climbing a steep slope.

In this state, the throttle valve 9 is opened to a high opening degree, and the opening degree of the throttle valve 9 is opened to 3/4 or more. On the other hand, the rotation speed of the engine also decreases from the rotation speed during normal high opening operation of the throttle valve 9, from 200 ORPM to 500 ORPM.
It is within the PM rotation speed range. The opening state of the throttle valve 9 is detected by a throttle valve opening sensor 31, and its output is input to a control circuit 33, while the rotational speed of the engine is detected by a rotation sensor 32.

The output is input to the control circuit 33.

When each output from the throttle valve opening sensor 31 and rotation sensor 32 is input to the control circuit 33, the control circuit 33
outputs a control signal for driving the control valve 23 to the control valve 23, and the control valve 23 that receives the control signal
In this case, the movable iron core 30 is attracted to the fixed iron core 29.

According to this, the return valve portion 27 comes into contact with the return valve seat 25 to cut off communication between the return passage 22 and the fuel increase passage 21, and the increase valve portion 2B separates from the increase valve seat 24.
The fuel increase passage 21 is brought into communication.

Therefore, the pressurized fuel pressurized by the fuel increase pump 20 and supplied to the fuel increase passage 21 immediately enters the intake passage 2 via the increase valve seat 26 without returning from the litter passage 22 into the fuel tank T. It is injected and supplied, and together with the fuel sucked into the intake passage z from the main fuel system, this prevents the mixture from becoming diluted during high opening and low speed operation.

The increased fuel is supplied from the fuel increase passage 21 into the intake passage 2 when the opening of the throttle valve 9 is 3/4 or more and the engine speed is within the range of 200 ORPM to 5000 RPM. This is performed continuously when a certain throttle valve 9 is operating at a high opening and low speed, and when the opening of the throttle valve 9 becomes 374 degrees or less or the engine speed falls outside the range of 200 ORPM to 5000 PPM. If either or both conditions are met, the output of the control signal from the control circuit 33 for driving the control valve 23 is stopped, and the control valve 23 returns to its original position and operates as a litter valve again. The portion 27 opens the return valve seat 25 and the increase valve portion 26 closes the increase valve seat 24, thereby stopping the supply of fuel from the fuel increase passage 21 to the intake passage 2.

Next, the second condition is during acceleration operation in which the throttle valve 9 is rapidly opened from a low opening to a high opening, the throttle valve 9 is in a low opening state, and the Al valve is in a low speed operation state. . From this state, the driver can open the throttle valve 9 by pulling the accelerator wire.
When the throttle valve 9 is rapidly opened to a high opening state and accelerated operation is performed, the behavior of fuel supply to the intake passage 2 when the throttle valve 9 is rapidly opened from a low opening state to a high opening state is as follows. It will be like this.

When the throttle valve 9 is in a low opening state, the engine speed is kept at idling speed (for example, 1200 PPM) or at a low speed. As the negative pressure in the intake passage increases, fuel is sucked out into the intake passage 2 from a low-speed fuel system (not shown) such as a bypass hole or a pilot outlet hole, and the engine is operated at a low opening and at a low speed.

Next, when the throttle valve 9 is rapidly opened from the low opening state to a high opening, the amount of air flowing through the intake passage 2 is increased at once;
The negative pressure at the tip of the needle jet 14 that opens at the end of the needle jet 14 temporarily increases. According to this, the fuel stored in the acceleration well W is sucked out from the needle jet 14 into the intake passage z via the mixing nozzle 15, thereby increasing the engine speed. In this state, the fuel in the acceleration well W is sucked out into the intake passage z via the needle jet 14 without being restricted from flowing in by the main jet IB, and has already been stored in the wake of the main jet 18. This is because they are in a state where they are easily sucked out. However, even if the fuel in the acceleration well W is sucked out, the fuel stored in the acceleration well W is controlled, so the rotational speed of the engine is not significantly increased.

That is, even if the throttle valve 9 is opened to a high opening degree, it is difficult to increase the engine speed to 5000 RPM or more. Although it is possible to increase the increase in rotational speed during acceleration by increasing the capacity in the acceleration well W, the inner and outer diameters of the mixing nozzle 15 are determined by taking into consideration the operability in other operating ranges. This is because the capacity of the acceleration well W is inevitably limited.

In such a state, in the present invention, the throttle valve 9
is opened to a high opening, and that the engine speed rises above idling speed but does not rise above 5000 RPM and remains within the speed range of 2000 RPM to 500 ORPM. The outputs of the sensor 31 and the rotation sensor 32 are input to the control circuit 33, and the control circuit 33 outputs a control signal for driving the control valve 23.

According to this, the return valve portion 27 of the valve portion V of the control valve 23
comes into contact with the return valve seat 25 and closes the return passage 22, and the increase valve part 2B opens the increase valve seat 24, so pressurized fuel is injected and supplied from the fuel increase passage 21 into the intake passage 2. This prevents the mixture from diluting and helps increase rotation during acceleration. And the engine speed is 500
When the ORPM is exceeded, the output of the control signal from the control circuit 33 to the control valve 23 is stopped, the return valve section 27 opens the return valve seat 25, and the increase valve section 2B closes the increase valve seat 24, so that the fuel Although the supply of fuel from the increase passage 21 to the intake passage 2 is cut off, since the rotational speed of one engine has sufficiently increased to 500 ORPM or more, a large intake passage is connected to the needle jet 14 as the main fuel system. Since negative pressure is applied, fuel suitable for high-opening operation of the throttle valve 9 can be sucked into the intake passage 2 from the needle jet 14.

The amount of additional fuel to be injected into the intake passage 2 from the fuel increasing passage 21 is determined by setting work with the engine, but for example, since a minute amount of fuel of about 5 cc/min is sufficient, the control valve A control jet I 34 having a passage diameter smaller than the effective passage diameter of the fuel increase passage 21 is disposed in the fuel increase passage 21 on the downstream side of the fuel increase passage 23 (on the side discharging to the intake path). By controlling the amount of fuel injected into the intake passage 2 from the fuel increase passage 21, it becomes easy to accurately control the increase in fuel that is suitable for high opening, low speed operation, and acceleration operation.

Furthermore, if the other end of the fuel increase passage 21 is opened to the intake pipe 2A on the engine side from the throttle valve 9 and the intake pipe (not shown) that communicates the carburetor and the engine, the engine and fuel can be connected to each other. The distance from the opening of the increase passage 21 is shortened, the increase fuel does not collide with the throttle valve, the throttle valve shaft, the jet needle, etc., and the increase fuel is supplied to the engine in an extremely short period of time. This enabled us to further improve the performance of the engine.

In addition, if a foreign object gets caught between the increase valve portion 2B of the control valve 23 and the increase valve seat 24, fuel will not continue to be supplied from the fuel increase passage 21 into the intake passage 2 while the engine is operating. However, from the fuel increase passage 21, the fuel tank T
A normally closed on-off valve 41 is disposed in the leak passage 40, and if the on-off valve 41 is opened in such a situation, the fuel for increase flowing through the fuel increase passage 21 will flow through the intake passage. The fuel was not supplied into the fuel tank T and was able to flow out into the fuel tank T. In particular, if the effective passage diameter of the leak passage 40 is made larger than the effective passage diameter of the fuel increase passage 21, the fuel increase passage 21
The fuel inside can be removed reliably and immediately. Note that the on-off valve 41 is not limited to a solenoid valve, but may be a zero manual valve.

Moreover, what is shown in FIG. 3 shows an embodiment in which a carburetor having an accelerator is combined with an increase device according to the present invention, which will be described below. (For structures that are the same as those in FIG. 1, the same reference numerals are used and explanations are omitted.) 50 is an accelerator, which has the following configuration.

That is, 51 is a diaphragm that divides the acceleration pump chamber 52 and the atmospheric chamber 53, and the acceleration pump chamber 52 has an acceleration pump chamber 52 connected to the inside of the float chamber 5 at one end and a suction side check valve 54 disposed therein. A fuel intake passage 55 and an acceleration nozzle 5 at one end.
8, and a discharge side check valve 5 inside.
The acceleration fuel discharge passage 58 in which the accelerating fuel discharge passage 7 is disposed is opened, and the diaphragm spring 59 that presses the diaphragm 51 toward the atmospheric chamber 53 is contracted. And throttle valve 9
The opening operation is an operation lever! 2. Link 60. It is applied to the diaphragm 51 via the pump lever 61.

That is, when the throttle valve 9 is opened, the diaphragm 51 reduces the volume of the acceleration pump chamber 52 by the pump lever 61 and pressurizes the acceleration pump chamber 52, thereby reducing the acceleration stored in the acceleration pump chamber 52. The fuel for this purpose is injected and supplied into the intake passage 2 through the acceleration nozzle 5B. The other end of the fuel increase passage 21, which is similar to the embodiment shown in FIG.

According to this structure, the supply of increased fuel from the fuel increase passage 21 to the carburetor during high opening and low speed operation and during acceleration operation is the same as in the first embodiment, but during acceleration operation, especially during acceleration operation, In addition to supplying fuel from the acceleration well W at the beginning of the process, acceleration fuel can also be supplied from the accelerator 50, which makes it possible to start up the rotation even more smoothly at the beginning of acceleration, and furthermore, it is possible to Now, let's set the acceleration fuel injection time, which took a lot of time to set.
The control valve 23 was opened in response to the output signal from the control circuit 33, and fuel was supplied to the acceleration nozzle 56 from the fuel increase passage 21, so that the desired acceleration fuel could be accurately supplied from the beginning to the end of acceleration. This made it possible to further improve acceleration performance.

In addition, the other end of the fuel increase passage 21 is particularly connected to the discharge side check valve 57.
According to the opening in the acceleration fuel discharge passage 58 between the acceleration nozzle 56 and the acceleration nozzle 56, the pressure of the fuel flowing in the fuel increase passage 21 is increased by the pressure load of the check valve spring that presses the discharge side check valve 57 against the discharge valve seat. Not subject to any restrictions.

That is, when the fuel increase passage 21 is opened in the acceleration fuel discharge passage 58 on the side of the acceleration pump chamber 52 from the discharge side check valve 57, the pressure of the fuel flowing in the fuel increase passage 21 is higher than the pressing load of the check valve spring. Otherwise, it is impossible to supply increased fuel through the acceleration fuel discharge passage, and it is necessary to increase the discharge pressure of the fuel pump P to increase the pressure of the fuel flowing in the fuel increased passage 21.

Furthermore, the opening of the fuel increase passage 21 that opens into the intake passage 2 of the carburetor body 1 has little freedom in design since it is drilled in a limited carburetor structure, but it has already been drilled. By using the acceleration fuel discharge passage 58 connected to the acceleration nozzle 5G, the fuel increase passage 21 can be routed easily.

〔Effect of the invention〕

As described above, the fuel increasing device for a carburetor according to the present invention provides the following effects.

■In a carburetor that mechanically controls opening and closing of the effective opening area of the intake passage using a throttle valve, during low-speed operation with a high opening of the throttle valve, the fuel increase passage is actively opened without depending on the negative pressure of the intake passage. By supplying pressurized fuel, it was possible to suppress the dilution of the air-fuel mixture, and it was possible to significantly improve engine performance without reducing engine performance.

■When there is no need to supply additional fuel from the fuel increase device to the intake passage, the fuel flowing into the fuel increase passage returns to the fuel tank via the return passage, so the atmospheric temperature of one engine rises and the fuel Even when paper is generated in the fuel increase passage, the paper can be discharged into the fuel tank, so paper lock is less likely to occur.

■The increased fuel to be fed into the fuel increase passage is not based on the fuel pressure from the fuel tank or the discharge pressure from the fuel pump, but rather the discharge pressure of the specially installed fuel increase pump, so it is transferred from the fuel increase passage into the intake passage. The injection pressure of the increased fuel can be set freely, especially on the high pressure side.

According to this, it was possible to improve fuel atomization and supply speed.

■During engine acceleration, if the engine speed cannot rise sufficiently even though the throttle valve is opened to a high opening, pressurized fuel is actively supplied from the fuel increase passage.
This prevents the dilution of the air-fuel mixture during acceleration, thereby improving the acceleration performance of the engine.

■This is because a control jet with a diameter smaller than the effective diameter of the fuel increase passage is placed in the fuel increase passage.

This enables minute fuel control, making it easy to select a control jet that is suitable for high-opening, low-speed, and accelerated throttle valve operation.

(2) By opening the other end of the fuel increase passage into the intake path on the side of the engine from the throttle valve, fuel can be instantly supplied to the engine, thereby improving the dynamic characteristics of the engine.

■By branching the leak passage from the fuel increase passage and arranging a normally closed on-off valve in the leak passage, the fuel flowing in the fuel increase passage can be removed when unnecessary, and the leak passage can be effectively used. When the passage diameter is made larger than the effective passage diameter of the fuel increase passage, the supply of increase fuel from the fuel increase passage can be instantly stopped.

■If the other end of the fuel increase passage is opened to the acceleration fuel discharge passage between the discharge side check valve of the accelerator and the acceleration nozzle, especially during the initial, middle and final stages of acceleration, the In conjunction with the fuel supply, pressurized fuel can be supplied from the fuel increase passage, and by using the already provided acceleration fuel discharge passage, only one passage can be easily routed, and furthermore, the fuel increase pump discharge Since the pressure is not affected by the closing force of the discharge side check valve, the discharge pressure can be easily set.

[Brief explanation of the drawing]

Fig. 1 is an overall system diagram including a vertical cross-sectional view of a carburetor showing an embodiment of the fuel increasing device for a carburetor according to the present invention, and Fig. 2 is a control circuit diagram showing the relationship between throttle valve opening and engine speed. FIG. 3 is an overall system diagram including a longitudinal sectional view of a carburetor showing another embodiment. 2: Intake path 6 Valve seat 17 Fuel inlet passage 21 Fuel increase passage 23 Control valve 32 Rotation sensor 34 Control Jet 41, Opening/closing valve 5B, Acceleration nozzle T, Fuel tank W, Acceleration well 5, Float chamber 9, Throttle valve 20, Fuel increase Pump 22, Return passage 31, Throttle valve opening sensor 33, Control circuit 40, Leak passage 50, Accelerator 57, Acceleration fuel discharge passage p, ,,,Fuel pump

Claims (6)

[Claims] (1) A carburetor that mechanically opens and closes the effective opening area of the intake passage that penetrates the carburetor body using a throttle valve; Fuel stored in a fuel tank is pressurized by a fuel pump to a fuel inlet passage that supplies fuel to a valve seat that opens into the float chamber; a fuel increase pump that sucks fuel in the fuel tank through the suction passage and discharges it through the discharge passage; one end connected to the discharge passage of the fuel increase pump; A fuel increase passage which is connected to the intake passage of the carburetor including the intake pipe at the other end; A return passage which branches from the fuel increase passage and which is connected to the fuel tank; A throttle valve opening sensor that detects the opening of the throttle valve. When the fuel increase passage is opened, the communication between the fuel increase passage and the return passage is cut off, and the communication between the fuel increase passage and the return passage is cut off by a control signal from a control circuit that receives the output and the output of a rotation sensor that detects the engine rotation speed. a control valve that communicates the fuel increase passage and the return passage when the passage is blocked; the control valve is operated by a control signal from a control circuit when the opening of the throttle valve is above a certain degree and within a certain rotational speed range of the engine; The fuel increase passage is opened and the communication between the fuel increase passage and the return passage is cut off, and the control valve is operated by a control signal from the control circuit when the opening of the throttle valve is below a certain degree and outside the constant rotation speed range of the engine. , a fuel increasing device for a carburetor, in which a fuel increasing passage is closed and a return passage is communicated with the fuel increasing passage. (2) A fuel increasing device for a carburetor according to claim 1, wherein a control jet having a passage diameter smaller than the effective passage diameter of the fuel increasing passage is disposed in the fuel increasing passage downstream of the control valve. . (3) The fuel increasing device for a carburetor according to claim 1, wherein the other end of the fuel increasing passage is opened to an intake path including an intake pipe on the engine side from the throttle valve. (4) The fuel increase passage for a carburetor according to claim 1, wherein a leak passage connected to the fuel tank is branched from the fuel increase passage, and a normally closed on-off valve is disposed in the leak passage. (5) The fuel increasing device for a carburetor according to claim 4, wherein the effective passage diameter of the leak passage is larger than the effective passage diameter of the fuel increasing passage. (6) At the other end of the fuel increase passage, in response to the rapid opening operation of the throttle valve, the accelerated fuel in the acceleration pump chamber is sucked in through the acceleration nozzle from the acceleration fuel discharge passage equipped with a discharge side check valve inside. 2. A fuel increasing device for a carburetor according to claim 1, which is opened in an acceleration fuel discharge passage between a discharge side check valve and an acceleration nozzle of an acceleration device for injecting and supplying fuel into a road.