JP3158304B2 - Vaporizer fuel booster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vaporizer for controlling the amount and concentration of an air-fuel mixture supplied to an engine.
The present invention relates to a fuel increasing device for a carburetor, which mechanically controls opening and closing of an effective opening area of an intake passage passing through a carburetor body by a throttle valve operated by an accelerator wire.

[0002]

2. Description of the Related Art Vaporizers which mechanically control the effective opening area of an intake passage by a throttle valve operated by an accelerator wire are roughly classified into the following two types. First, a valve shaft is rotatably supported by the carburetor body across an intake path penetrating the carburetor body, and a disc-shaped butterfly valve is attached to the valve shaft. A venturi section is formed in the intake passage upstream of the butterfly valve, and a fuel injection hole is formed in the venturi section, which is connected to the float chamber below the constant liquid level. here,
When the driver rotates the valve shaft by operating the accelerator wire, the butterfly valve controls opening and closing of the effective opening area of the intake passage. (Usually referred to as a butterfly type vaporizer, which is shown in, for example, Japanese Utility Model Publication No. 50-43617).

[0003] Second, a sliding valve guide cylinder is continuously provided laterally from an intermediate portion of an intake passage penetrating the carburetor body, and a cylindrical or short throttle valve is provided in the sliding valve guide cylinder. Is slidably disposed, and a venturi portion is formed by the bottom of the throttle valve and the intake passage, and a fuel injection hole continuous below the constant liquid level of the float chamber is opened in the venturi portion. Here, when the driver operates the accelerator wire to move the throttle valve within the sliding valve guide cylinder, the throttle valve controls opening and closing of the effective opening area of the intake passage (the area of the venturi portion). (It is usually called a sliding throttle valve type carburetor, and is shown in, for example, Japanese Utility Model Publication No. 52-54671.)

[0004] The above-mentioned butterfly carburetor and sliding throttle valve carburetor which mechanically controls the effective opening area (the area of the venturi portion) of the intake passage by the throttle valve have the following problems. First, the throttle valve is opened to a high opening,
When the speed of the vehicle is low (high-opening low-speed operation), the flow velocity of the air flowing through the venturi becomes low, and the venturi negative pressure applied to the fuel injection holes opened to the venturi is weakened. According to this, it becomes difficult to suck out sufficient fuel from the fuel injection hole into the venturi portion, and this is not preferable because the mixture becomes lean. The mixture leaning phenomenon in the high opening low speed operation becomes more remarkable as the intake passage diameter is increased (the diameter of the venturi portion is increased) in order to improve the output of the engine. As a conventional technique aimed at solving the above, an air control valve is arranged upstream of the throttle valve, and at the time of high opening low speed operation, air output is obtained by the output of the throttle valve opening sensor and the output of the engine rotation speed sensor. A technique for controlling a control valve in a closing direction is known. (Shown in Japanese Utility Model Laid-Open No. 60-70761.)

[0005] Second, in the case of a rapid acceleration operation of an engine in which the throttle valve is rapidly opened to a high opening in order to rapidly increase the rotation from a low opening state as in the case of an idling operation of the engine. In consideration of the above, although the increased amount of air is supplied to the engine immediately by the rapid opening of the throttle valve, the supply of fuel is temporarily delayed due to the inertia of the air, resulting in the dilution of the air-fuel mixture. Not preferred. This leaning of the air-fuel mixture becomes more prominent as the diameter of the intake passage is increased (the diameter of the venturi portion is increased). As a conventional technique for solving the above,
The housing is divided into a pump room and an atmosphere room by a diaphragm,
In the pump chamber, an intake-side check valve is arranged inside, and the accelerated fuel inflow passage connected to the float chamber, and the discharge-side check valve is arranged inside, the accelerated fuel discharge passage connected to the intake passage. The diaphragm is pressed toward the pump chamber during the rapid opening operation of the throttle valve to pressurize the pump chamber, and the fuel for acceleration stored in the pump chamber is injected and supplied into the intake passage via the accelerated fuel discharge passage. There is a technology of a so-called acceleration pump device. (Shown in Japanese Utility Model Publication No. 46-43050)

[0006]

However, the conventional technique has the following disadvantages. First, Showa 60-707
According to the technology of No. 61, at the time of high opening low speed operation, the throttle valve is kept open at a high opening, but the air control valve controls the intake path in the closing direction by an output signal from the control unit to restrict the throttle. This is to reduce the effective opening area of the intake passage upstream of the valve. According to this, the intake path negative pressure in the intake path including the throttle valve on the engine side from the air control valve rises, and the opening of the needle jet as the main fuel system that opens to the venturi section on the engine side from the air control valve The negative pressure of the intake passage applied to the portion is increased, so that a larger amount of fuel can be sucked into the intake passage than the needle jet, thereby preventing the mixture from being lean. However, according to the fact that the air control valve operates the intake passage in the closing direction to reduce the effective opening area of the intake passage, the amount of air supplied to the engine is reduced, which is not preferable in that the output of the engine is improved. .

Next, the technique of Japanese Patent Publication No. 46-43050 is
The pump chamber is pressurized by the rapid opening operation of the throttle valve, and the accelerating fuel stored in the pump chamber is injected and supplied into the intake passage via the accelerating fuel discharge passage. However, it is difficult to set a long acceleration fuel injection time (continuous injection from the initial stage to the final stage of acceleration) supplied from the acceleration pump device into the intake passage. This is due to the fact that the diaphragm for pressurizing the pump chamber of the acceleration pump device is mechanically connected to the throttle valve. Selection of a diaphragm spring that is contracted in the room and urges the diaphragm toward the atmosphere chamber, selection of the diameter of the accelerating fuel suction path and accelerating fuel discharge path, or a suction-side check valve and a discharge-side check valve It takes a lot of time to select a valve-closing spring for pressing and biasing against the seat and the like, and this hinders improvement in development efficiency. Even if each of the above-described elements is selected, there is a limit to extending the acceleration fuel injection time from the initial period to the final period of acceleration since the compression stroke of the diaphragm is uniquely determined by the opening stroke of the throttle valve. It is. In addition, during the acceleration operation from the intermediate opening operation of the throttle valve, the diaphragm is already in a state where the pump chamber is compressed, and it is difficult to further compress the diaphragm. Therefore, sufficient acceleration fuel can be supplied. There was no fear.

A fuel increasing device for a carburetor according to the present invention has been made in view of the above. In a carburetor in which an effective opening area of an intake passage is mechanically controlled to be opened and closed by a throttle valve, the fuel supply device is provided with a high opening in the engine. It is an object of the present invention to provide a fuel increasing device capable of suppressing leanness of the air-fuel mixture during low-speed operation and acceleration operation, and positively enriching the air-fuel mixture in a specific operation region where the air-fuel mixture becomes lean. Things.

[0009]

According to the fuel increasing device for a carburetor according to the present invention, in order to achieve the above object, the effective opening area of the intake passage passing through the carburetor body is mechanically opened and closed by a throttle valve. Controlling and pressurizing the fuel stored in the fuel tank and the fuel stored in the fuel tank to the valve seat opened in the float chamber of the vaporizer by controlling the vaporizer having the venturi formed in the intake passage. A fuel inflow passage, a fuel increasing passage connected at one end to the fuel inflow passage and the other end connected to an intake passage of a carburetor including an intake pipe, and a throttle valve opening disposed in the fuel increasing passage for detecting the opening of the throttle valve. The amount of fuel is increased by a control signal from a control circuit to which an output of a degree sensor and an output of a pressure sensor for detecting a negative pressure in the intake pipe connected to the engine from the throttle valve or an intake pipe connected to the engine (a negative pressure in the intake pipe) are input. Open and close passage And a control valve for controlling the amount of fuel flowing through the fuel increasing passage. The control valve controls the amount of fuel in the fuel increasing passage by controlling the amount of fuel in the fuel increasing passage when the opening of the throttle valve is equal to or more than a predetermined opening degree and the throttle valve When the opening of the throttle valve is in a constant state within the range of the negative pressure in the intake pipe defined within the range of the opening of the throttle valve, the fuel amount is reduced in accordance with the rise of the negative pressure in the intake pipe and the throttle is reduced. In a state where the opening degree of the valve is increasing, the fuel amount is reduced in accordance with an increase in the negative pressure in the intake pipe.

[0010]

The control valve is controlled by a control signal from the control circuit when the opening of the throttle valve is equal to or greater than a predetermined opening and is within the range of the opening of the throttle valve and within a predetermined range of the negative pressure in the intake pipe. Operate to open the fuel increase passage. According to this, the pressurized fuel in the fuel inflow passage is injected and supplied into the intake passage through the fuel increasing passage, thereby suppressing the mixture from being lean. On the other hand, when the opening degree of the throttle valve is equal to or less than the predetermined opening degree and is within the specified opening degree range of the throttle valve and outside the specified intake pipe negative pressure range, the fuel increasing passage is closed by the control valve. The fuel supply from the fuel increasing passage to the inside of the intake passage is suppressed. At this time, the opening of the throttle valve is in a constant opening state within a predetermined opening range of the throttle valve that is equal to or more than a certain opening degree of the throttle valve and within a predetermined range of the negative pressure in the intake pipe. In other words, the fuel amount is reduced according to the increase in the intake pipe negative pressure, and the fuel amount is reduced according to the increase in the intake pipe negative pressure when the throttle valve opening is increasing.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a fuel increasing device for a carburetor according to the present invention will be described below with reference to FIG. This embodiment is an embodiment in a sliding throttle valve type carburetor. Reference numeral 1 denotes a carburetor body in which an intake passage 2 penetrates and a sliding valve guide cylinder 3 is continuously provided upward from a substantially middle portion of the intake passage 2. The carburetor body 1 faces a lower concave portion of the carburetor body 1. The float chamber main body 4 is disposed, and the lower concave portion and the float chamber main body 4 form a float chamber 5. A valve seat 6 is opened in the float chamber 5, and a float valve 7 for controlling the opening and closing of the valve seat 6 is arranged corresponding to the valve seat 6, and the float valve 7 is a float valve arranged in the float chamber 5. The opening and closing driving force for the valve seat 6 is given by the movement of the valve seat 6.

A throttle valve 9 for controlling the opening and closing of the effective opening area of the intake passage 2 is movably arranged in the sliding valve guide cylinder 3, and this throttle valve 9 is rotatable with respect to the carburetor body 1. An operating lever 12 is mechanically connected to an operating shaft 10 pivotally supported by a link, a lever, and the like, and an operating lever 12 is integrally attached to a shaft end of the operating shaft that protrudes outside the carburetor body 1. An accelerator wire (not shown), which is operated by a driver, is attached to the operation lever 12. Therefore, when the driver operates the accelerator wire, the operation lever 12 and the operation shaft 10 rotate, and this is transmitted to the throttle valve 9 via a lever, a link or the like, and the throttle valve 9 is moved to the intake passage 2.
Will be opened and closed. Then, a venturi portion 11 is formed by the bottom 9A of the throttle valve 9 opening into the intake passage 2 and the intake passage 2 opposed thereto. The opening area of the venturi section 11 changes with the movement of the throttle valve 9.
(Forms a so-called variable venturi)

A jet needle 13 is integrally attached to the bottom 9A of the throttle valve 9. The jet needle 13 is inserted into a needle jet 14 serving as a fuel injection hole opened in the venturi section 11. Is done. The needle jet 14 is connected to a main fuel jet 16 via a mixing nozzle 15 having an air bleed hole 15A, and an annular acceleration well W is formed around the mixing nozzle 15 described above. This acceleration well W
A liquid surface having substantially the same height as a constant liquid surface formed in the float chamber 5 is formed therein, and a main air passage communicating with the atmosphere is opened in the acceleration well W above the liquid surface. (The main air passage is not shown)

On the other hand, a fuel inflow passage 17 is provided in the valve seat 6.
The fuel stored in the fuel tank T is supplied in a pressurized state via the fuel tank T. When the fuel tank T is disposed below the carburetor body 1, the fuel in the fuel tank T Pressurized by the fuel pump P, the fuel inflow path 17
When the fuel tank T is disposed above the carburetor body 1, the fuel in the fuel tank T (indicated by a dotted line in FIG. 1) is pressurized by the fuel head difference and flows into the fuel tank T. It is supplied to the road 17. The position of the fuel tank T is not limited. 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, and the fuel flows into the float chamber 5 from the fuel inflow path 17 through the valve seat 6. When the liquid level in the float chamber 5 rises to a set constant liquid level, the float valve 7 closes the valve seat 6 with the float 8, and the float valve 7 closes from the fuel inflow passage 17 through the valve seat 6. The supply of fuel to the inside of the float 5 is stopped, so that a constant liquid level can always be formed in the float chamber 5. The above is a conventionally known vaporizer.

Reference numeral 20 denotes an increased fuel amount, one end of which is connected to the fuel inflow passage 17 and the other end of which is connected to the intake passage 2 or an intake pipe (not shown) which connects the intake passage 2 of the carburetor body 1 to the engine. It is a passage, and the opening position is not limited within the above range. In this embodiment, the fuel increasing passage 20 is opened on the upstream side (left side in FIG. 1) of the throttle valve 9. Reference numeral 21 denotes a control valve which is disposed in the fuel increasing passage 20 and controls opening and closing of the fuel increasing passage 20. In the present embodiment, the movable core 23 is attracted to the fixed core 24 by energizing the solenoid 22, and the movable core 23 Valve part 25 formed integrally with
Used a normally closed solenoid valve that opens a valve seat 26 provided in the fuel increasing passage 20. (The control valve 21 may be appropriately selected as long as it has a function (for example, a motor) that electrically opens and closes the passage without being a solenoid valve.)

Reference numeral 27 denotes a throttle valve opening sensor for detecting the opening of the throttle valve 9 with respect to the intake passage 2, and reference numeral 28 denotes an intake passage 2 on the engine side (right side in FIG. 1) of the throttle valve 9 or an intake pipe connected to the engine (both of them). The pressure sensor is a pressure sensor for detecting a negative pressure (negative pressure in an intake pipe) in the pressure sensor.
The pressure conversion element is, for example, a silicon diaphragm type using a piezoresistive effect of a semiconductor, and has a vacuum chamber on one side of the silicon diaphragm and an engine from the throttle valve 9 via the negative pressure introduction path 29 on the other side. A negative pressure in the intake passage 2 on the side or the intake pipe connected to the engine. In the present embodiment, the negative pressure introduction passage 29 opens from the throttle valve 9 to the intake passage 2 on the engine side.

The outputs of the throttle valve opening sensor 27 and the pressure sensor 28 are input to a control circuit 30 to determine the opening of the throttle valve 9 and the negative pressure in the intake passage from the throttle valve 9 or in the intake pipe connected to the engine. Under the specified conditions, a control signal for driving the control valve 21 is output from the control circuit 30. An example of the conditions in which the control circuit 30 outputs a control signal for driving the control valve 21 from the control circuit 30 and the conditions for determining the throttle valve opening and the intake pipe negative pressure are as follows. In a state where the throttle valve is opened at the opening degree or more, and within a range of the negative pressure in the intake pipe defined within the range of the opening degree of the throttle valve, a control signal for driving the control valve 21 from the control circuit 30 is output. Is output. For example, when the throttle valve opening is 3/8, the negative pressure in the intake pipe is in the range of -3 mmHg to -200 mmHg, and when the throttle valve opening is 5/8, the negative pressure in the intake pipe is -3 mHg.
mHg to −40 mmHg, and the throttle valve opening 7
In / 8, the intake pipe negative pressure is -16 m from -3 mmHg
mHg range. The condition range is clearly shown in a hatched range in FIG. 2, but this condition range is appropriately set at the time of setting operation of the carburetor for the engine, and is not limited to the condition.

Next, the operation will be described. First, a description will be given of a relatively low opening operation state in which the opening of the throttle valve 9 is equal to or less than 3/8 opening. The opening of the throttle valve 9 is constant (3/8 opening).
The control signal for driving is not output from the control circuit 30 to the control valve 21 because it has not been opened to this point. Therefore, the control valve 21 is in a non-operating state, and the valve portion 25 of the control valve 21 closes and holds the valve seat 26, so that the increased fuel is not supplied from the fuel increasing passage 20 to the intake passage 2. During such a low opening operation, the venturi portion 11 is narrowed to a small opening area by the throttle valve 9, and the air flow velocity flowing through the venturi portion 11 having the small opening and the intake passage downstream of the venturi portion 11 is increased. As a result, the negative pressure in the venturi section 11 and the intake passage downstream of the venturi section 11 rises and is maintained.
4 and an unillustrated low-speed fuel system bypass hole and pilot outlet hole, the optimal fuel is sucked into the venturi section 11 and the intake passage 2 and supplied to the engine, so that the engine is operated at a low opening degree satisfactorily. .

Next, when the throttle valve 9 is operated at a high opening degree and the load applied to the engine is higher than 3/8 or more when the throttle valve 9 is opened at a relatively low opening degree or less at the above 3/8 opening degree. Under light or medium load conditions, the engine speed
Since the throttle valve 9 is opened at a medium and high opening degree and the load is not relatively large, the throttle valve 9 appropriately rises. As a result, the air velocity flowing through the venturi portion 11 increases, and the venturi portion 11 and the throttle valve 9 The negative pressure in the intake passage 2 on the engine side is sufficiently increased, and appropriate fuel corresponding to the negative pressure is drawn into the intake passage 2 from the needle jet 14, and becomes appropriate according to the throttle valve opening. Middle-high opening operation can be performed. More specifically, with reference to FIG. 2, when the throttle valve opening is 4/8, the negative pressure in the intake pipe is -80 mmH.
g, and the negative pressure in the intake pipe becomes-at the throttle valve opening of 6/8.
Exceeding 24 mmHg, the negative pressure in the intake pipe exceeds -10 mmHg at the throttle valve opening of 8/8. Therefore, the control circuit 3
From 0, no control signal for driving is output to the control valve 21, and the control valve 21 closes and holds the fuel increasing passage 20. As described above, while the throttle valve 9 is at the time of the high opening operation and the load applied to the engine is small and at the time of the medium load operation, the fuel is not increased from the fuel increasing passage 20 as described above. Since the negative pressure of the venturi section 11 is sufficiently increased, the most suitable fuel can be supplied from the needle jet 14 as the main fuel system.
The throttle valve is supplied to the engine and is supplied to the engine to satisfy the operation of the engine. Thus, a desired high-speed operation according to the throttle valve opening can be obtained.

The fuel increasing device for a carburetor according to the present invention has a special effect in the following. First, a driving state in which the vehicle speed does not sufficiently increase despite the throttle valve 9 being opened at a high opening while the throttle valve 9 is 3/8 or more opening. Such a situation is a state in which the throttle valve 9 is opened to a high degree at the middle and a high degree of opening to apply a high load to the engine. For example, this state corresponds to a state of climbing a steep slope or a state in which loads are fully loaded. In such a state, the throttle valve 9 is opened at a high opening in the middle of the opening of 3/8 or more. On the other hand, the rotation speed of the engine is reduced by the application of a high load, and the air flow rate flowing through the venturi section 11 is reduced. Drops, venturi part 11
Further, as the negative pressure of the intake passage 2 on the engine side with respect to the throttle valve 9 decreases, the amount of fuel sucked into the intake passage 2 from the needle jet 14 decreases, and the air-fuel mixture becomes lean. Driving cannot be obtained. For example, when the throttle valve opening is 4/8, the negative pressure in the intake pipe is -80 m.
It is less than mHg, the negative pressure in the intake pipe is less than -24 mmHg at the throttle valve opening of 6/8, and the negative pressure in the intake pipe is less than -10 mmHg at the throttle valve opening of 8/8. When this state is reached, the opening state of the throttle valve 9 is detected by the throttle valve opening sensor 27, and its output is input to the control circuit 30, while the negative pressure in the intake pipe is detected by the pressure sensor 28. The output is input to the control circuit 30.

When the outputs from the throttle valve opening sensor 27 and the pressure sensor 28 are input to the control circuit 30, the control circuit 30 sends a control signal for driving the control valve 21 to the control valve 21. The control valve 21 receives the control signal, and the valve portion 25 opens the valve seat 26 when the movable iron core 23 is attracted to the fixed iron core 24. According to this, a part of the pressurized fuel supplied into the fuel inflow passage 17 is separated from the fuel inflow passage 17 and is immediately injected and supplied from the fuel increasing passage 20 into the intake passage 2. The throttle valve, combined with the fuel sucked into the venturi section 11 from the needle jet 14, suppresses the leaning of the air-fuel mixture during high-load operation in which the throttle valve is opened at a medium or high opening. The opening degree and high load operation can be performed satisfactorily. The supply of increased fuel from the fuel increase passage 20 into the intake passage 2 is performed when the opening of the throttle valve 9 is equal to or more than 3/8 opening and the negative pressure in the intake pipe is determined by the opening of the throttle valve. It is performed continuously within the range. (In other words, the negative pressure in the intake pipe has not risen to an appropriate value for the throttle valve opening.) For example, at a throttle valve opening of 4/8, the negative pressure in the intake pipe is in the range of -3 mmHg to -80 mmHg. At an opening degree of 6/8, the negative pressure in the intake pipe is changed from -3 mmHg to -24 mmHg.
The negative pressure in the intake pipe is in the range of −3 mmHg to −10 mmHg at the throttle valve opening of 8/8. Then, when the opening of the throttle valve 9 is equal to or less than 3/8 opening, or when the opening of the throttle valve 9 is equal to or more than 3/8 opening and the negative pressure in the intake pipe is determined with respect to the opening of the throttle valve. (In other words, when the negative pressure in the intake pipe has risen appropriately with respect to the determined throttle valve opening degree), the control valve 21 is driven. The output of the control signal from the control circuit 30 is stopped, the control valve 21 returns to the original position, and the valve section 26 closes the valve seat 26,
Thus, the supply of fuel from the fuel increasing passage 20 to the intake passage 2 is stopped.

Next, the second is an acceleration operation in which the throttle valve 9 is rapidly opened from a low opening to a medium or high opening. The throttle valve 9 is in a low opening state, and the engine operates at a low speed. In operation. In this state, the driver pulls the accelerator wire to quickly open the throttle valve 9 to the middle and high opening state to perform the acceleration operation. Here, the behavior of fuel supply to the intake passage 2 when the throttle valve 9 is rapidly opened from the low opening state to the middle and high opening states is as follows. When the throttle valve 9 is in the low opening state, the rotation speed of the engine is idling (for example, 1).
In this state, fuel is sucked into the intake passage 2 from a low-speed fuel system (not shown) such as a bypass hole and a pilot outlet hole to operate the engine at a low opening degree and low speed. Do. Then
When the throttle valve 9 is rapidly opened to a middle or high opening degree from the low opening state of the throttle valve 9, the amount of air flowing through the intake passage 2 is increased at a stretch. The negative pressure at the tip of the needle jet 14 opening into the inside temporarily rises slightly. According to this, the fuel stored in the acceleration well W is sucked into the venturi section 11 from the needle jet 14 via the mixing nozzle 15 to increase the engine speed. In this state, the fuel in the accelerating well W is sucked into the venturi section 11 via the needle jet 14 because the needle jet 1
The negative pressure of the intake passage that is applied to the opening of the nozzle 4 temporarily rises slightly, and is not limited by the inflow by the main jet 16, and is already stored in the acceleration well W downstream of the main jet 16. This is due to being in a state where it is easily sucked out. However, even if the fuel in the accelerating well W is sucked out, the amount of fuel stored in the accelerating well W is limited, so that the rotation speed of the engine is not significantly increased. That is, even if the throttle valve 9 is opened to a medium or high opening, it is difficult to immediately increase the vehicle speed according to the throttle valve opening. If the capacity in the acceleration well W is increased, the rotation speed during acceleration can be increased to increase the vehicle speed.
Is determined in consideration of the operability in other operation regions, so that the capacity of the acceleration well W is necessarily limited. In such a state, in the present invention, the throttle valve is opened at a high opening or higher while the throttle opening is 3/8 or higher, and the engine speed is higher than the idling rotation. Since the negative pressure in the intake pipe on the engine side does not increase significantly (cannot increase) from the throttle valve 9 without greatly increasing, the outputs of the throttle valve opening sensor 27 and the pressure sensor 28 for detecting the negative pressure are input to the control circuit 30. A control signal for driving is output from the control circuit 30 to the control valve 21. According to this, since the valve portion 25 of the control valve 21 immediately opens the valve seat 26, the fuel pressurized from the fuel increasing passage 20 is injected and supplied into the intake passage 2. The leaning of the air is suppressed, and the rotation speed during acceleration is assisted to increase the vehicle speed according to the throttle valve opening. When the engine speed is sufficiently increased in response to the supply of fuel from the fuel increasing passage 20 and the vehicle speed is appropriately increased in accordance with the throttle valve opening, the throttle valve 9 is moved from the throttle valve 9 into the engine-side intake passage. The negative pressure in the intake pipe also rises sufficiently, the control circuit 30 stops outputting the control signal to the control valve 21, and the supply of fuel from the fuel increasing passage 20 is cut off. Since the vehicle speed is sufficiently increased and the vehicle speed is appropriately increased according to the opening degree of the throttle valve, a large negative pressure acts on the needle jet 14 as the main fuel system. The fuel that conforms to the above can be sucked into the intake passage 2 from the needle jet 14. In the case of the acceleration operation described above, FIG.
A more specific example will be described.
Open the throttle valve 9 quickly to 4/8 opening from -8m
mHg, the throttle valve opening sensor 27,
The output of the pressure sensor 28 is input to the control circuit 30, and the control circuit 30 outputs a signal for driving the control valve 21.
According to this, the fuel is immediately supplied from the fuel increasing passage 20 toward the intake path 2, the leanness of the air-fuel mixture is suppressed, the rotation of the engine is increased, and the vehicle speed can be increased according to the throttle valve opening. As described above, when the engine rotation increases, the negative pressure in the intake pipe also increases. When the negative pressure in the intake pipe exceeds -80 mmHg, the output from the pressure sensor 28 to the control circuit 30 is stopped. As a result, the output from the control circuit 30 to the control valve 21 is stopped, and the supply of fuel from the fuel increasing passage 20 to the intake passage 2 is stopped.

Further, even during an intermediate acceleration operation in which the throttle valve 9 is rapidly opened from an intermediate opening degree, for example, 4/8 opening degree to 8/8 opening degree (full opening), the negative pressure of the venturi section 11 is temporarily reduced. It does not increase, the increase in the rotational speed is suppressed, the increase in the negative pressure in the intake pipe is suppressed, and the vehicle speed may not increase to a desired speed. Even in such a state, the control valve 21 outputs the signal output from the control circuit 30. With the above operation, the intermediate acceleration operation can be improved. Explaining with a specific example with reference to FIG. 2, the throttle valve 9 is opened to an 8/8 opening (fully open) from a throttle valve opening of 4/8 and a negative pressure in the intake pipe of -100 mmHg to reduce the negative pressure in the intake pipe to -5 mmHg. When the pressure decreases, outputs from the throttle valve opening sensor 27 and the pressure sensor 28 are input to the control circuit 30, and a signal for driving the control valve 21 is output from the control circuit 30.
1 opens the fuel increasing passage 20 and immediately supplies the fuel to the intake passage 2 to prevent the mixture from becoming lean, thereby increasing the engine speed and increasing the vehicle speed according to the throttle valve opening. it can. And the negative pressure in the intake pipe is -10m due to the increase of rotation.
When the pressure rises above mHg, the control circuit 3
When the output to 0 is stopped, the output from the control circuit 30 to the control valve 21 is stopped, and the supply of fuel from the fuel increasing passage 20 to the intake path 2 is stopped.

According to the present invention, the following features are provided. A control signal output from the control circuit 30 to the control valve 21 is a drive pulse having a conduction time Ti,
When the opening degree of the throttle valve 9 is equal to or more than 3/8 opening degree and is within the range of the throttle valve opening degree and is determined in the intake pipe negative pressure,
When the opening of the throttle valve 9 is in a constant opening state, the energizing time Ti is shortened in accordance with the rise of the negative pressure in the intake pipe, and the fuel increasing passage 2
When the amount of fuel supplied from 0 to the intake passage 2 is reduced, while the throttle valve 9 is in the open state, the energizing time Ti is shortened in accordance with the increase in the negative pressure in the intake pipe to increase the fuel. Passage 2
It is preferable to reduce the amount of fuel supplied from 0 toward the intake path 2. Such a fuel control state is clearly shown in FIG.
In FIG. 3, the mesh area has the largest amount of fuel supplied from the control valve 21, and the solid line hatching area (referred to as a large flow rate) has the second largest fuel quantity (medium flow rate).
Further, the amount of fuel in the hatched area indicated by the dotted line is larger than that in the hatched area indicated by the solid line. According to the above (referred to as a small flow rate), for example, when the opening degree of the throttle valve 9 is constant and the negative pressure in the intake pipe increases from -3 mmHg to -200 mmHg, the negative pressure is supplied to the intake passage 2 through the fuel increasing passage 20. The amount of fuel to be supplied can be gradually reduced to a large flow rate, a medium flow rate, and a small flow rate. In particular, the negative pressure of the venturi section 11 is so low that it is difficult to suck fuel into the venturi section 11 from the needle jet 14 (for example, When the negative pressure in the intake pipe is -5 mmHg, a large amount of fuel increase correction can be performed, while the suction of fuel from the needle jet 14 into the venturi section 11 is better than the above state (for example, negative pressure in the intake pipe). Is -40 mmHg), it is possible to perform a fuel increase correction of a small flow rate, and it is extremely difficult in terms of engine operability, emission of harmful exhaust gas, and fuel economy. Achieves the effect becomes.

Further, an appropriate fuel correction can be performed depending on the degree of opening of the throttle valve. Referring to FIG. 3, a specific example will be described. When the throttle valve 9 is opened from 2/8 opening to 4/8 opening, the negative pressure in the intake pipe decreases to -10 mmHg,
According to this, the throttle valve opening sensor 27 and the pressure sensor 28
Is input to the control circuit 30, and a signal for driving the control valve 21 is output from the control circuit 30. According to this, the fuel at the medium flow rate is increased from the fuel increasing passage 20, whereby the rotation is increased and the negative pressure in the intake pipe is reduced by-
When the pressure rises to 22 mmHg, a small amount of fuel is increased, and the rotation further rises to reduce the negative pressure in the intake pipe to -80 mmHg.
When the pressure exceeds the limit, the fuel increase from the fuel increase passage 20 stops. When the throttle valve 9 is opened from the 2/8 opening to the 8/8 opening, the negative pressure in the intake pipe is greatly reduced to -5 mmHg, whereby the control valve 21 increases the fuel amount by the signal output from the control circuit 30. A large amount of fuel is increased from the passage 20, thereby increasing the rotation. When the rotation increases, the intake pipe negative pressure rises to -8 mmHg, and the medium flow rate fuel increases. When the rotation further increases and the intake pipe negative pressure rises to -9 mmHg, the small flow fuel increases. When the rotation further rises and the negative pressure in the intake pipe exceeds -10 mmHg, the fuel increase from the fuel increase passage 20 stops.

Also, a large flow rate within the mesh range described above,
When the control valve 21 is controlled by arbitrarily changing the energization time Ti in each of the medium flow rate in the hatched area indicated by the solid line and the small flow rate in the hatched area indicated by the dotted line, the fuel is supplied from the fuel increasing passage 20 into the intake passage 2. Fuel control can be made more precise and finer. Alternatively, the control valve 21 may be a linear solenoid valve in which the valve portion 25 moves linearly with respect to the valve seat 26 so that the opening area thereof can be varied steplessly.
In the above-described embodiment, the amount of the increased fuel to be injected from the fuel increasing passage 20 into the intake passage 2 is determined by a setting operation with the engine, but a small fuel amount of, for example, about 5 cc / min may be used. A control jet J having a passage diameter smaller than the effective passage diameter of the fuel increase passage 20 is disposed in the fuel increase passage 20 downstream of the control valve 21 (a side discharging to the intake passage 2). Fuel increase passage 2
When the amount of fuel injected into the intake passage 2 is controlled from 0, accurate control of the increased fuel is facilitated.

[0027]

As described above, according to the fuel increasing device for a carburetor according to the present invention, the control of the fuel amount in the fuel increasing passage by the control valve is performed when the opening degree of the throttle valve is equal to or more than a predetermined opening degree and the throttle valve is controlled. When the opening of the throttle valve is in a constant opening state within the range of the negative pressure in the intake pipe determined within the range of the opening, the fuel amount is reduced according to the increase in the negative pressure in the intake pipe, With the throttle valve opening increasing, the fuel amount was reduced in response to the rise in the negative pressure in the intake pipe, and the fuel control characteristics of the carburetor could be matched to the engine requirements in a very short time. The engine performance was significantly improved and the development efficiency was significantly improved.

[Brief description of the drawings]

FIG. 1 is an overall system diagram including a vertical cross-sectional view of a carburetor showing an embodiment of a fuel increasing device for a carburetor according to the present invention.

FIG. 2 is a diagram showing an entire range in which an output for driving is output from a control circuit to a control valve in a relationship between a throttle valve opening and a negative pressure in an intake pipe.

FIG. 3 is a diagram showing details of a range in which an output for driving is output from a control circuit to a control valve in a relationship between a throttle valve opening and a negative pressure in an intake pipe.

[Explanation of symbols]

 Reference Signs List 2 intake path 5 float chamber 6 valve seat 9 throttle valve 11 venturi section 14 needle jet 17 fuel inflow path 20 fuel increasing path 21 control valve 27 throttle valve opening sensor 28 pressure sensor 30 control circuit 31 pressure regulator

Claims (1)

(57) [Claims] 1. A carburetor in which an effective opening area of an intake passage penetrating a carburetor body is mechanically controlled by a throttle valve to open and close, and a carburetor having a venturi portion formed in the intake passage, and a fuel stored in a fuel tank. A fuel inflow passage for supplying pressure to a valve seat that opens into the float chamber of the carburetor by pressurizing the fuel with a fuel head difference or a fuel pump; A fuel increasing passage connected to the road, an output of a throttle valve opening sensor that is disposed in the fuel increasing passage, and detects an opening of the throttle valve, and a negative pressure in an intake passage on the engine side from the throttle valve or an intake pipe connected to the engine ( A control valve for controlling opening and closing of the fuel increasing passage and controlling the amount of fuel flowing in the fuel increasing passage by a control signal from a control circuit to which an output of a pressure sensor for detecting the negative pressure in the intake pipe is input. control The control of the fuel amount in the fuel increasing passage by the valve is performed when the opening of the throttle valve is equal to or more than a certain opening, and within a range of the negative pressure in the intake pipe determined within the range of the opening of the throttle valve. When the opening of the throttle valve is constant, the fuel amount is reduced according to the increase in the negative pressure in the intake pipe, and when the opening of the throttle valve is increasing, the fuel amount is reduced in accordance with the increase in the negative pressure in the intake pipe. A fuel increasing device for a carburetor that reduces the amount of fuel.