JP3188981B2 - 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 passage penetrating the carburetor body, and a disc-shaped butterfly valve is attached to the valve shaft. A venturi section is formed in the intake path on the upstream side of the butterfly valve, and a fuel injection hole that opens below the constant liquid level of the float chamber opens in the venturi section. Here, when the driver rotates the valve shaft by operating the accelerator wire, the effective opening area of the intake passage is controlled to be opened and closed by the butterfly valve. (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 from an intermediate portion of an intake passage penetrating the carburetor body to the side, and a cylindrical or rectangular throttle valve is provided in the sliding valve guide cylinder. It 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 JP-B-46-43050.)

[0006]

However, the conventional technique has the following disadvantages. First, 60-70
According to the technology of No. 761, at the time of high opening low speed operation,
Although the throttle valve is kept open at a high opening, the air control valve controls the intake path in the closing direction by an output signal from the control unit to reduce the effective opening area of the intake path upstream of the throttle valve. It is. 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. was there.

In view of the above, a fuel increasing device for a carburetor according to the present invention is a carburetor in which the effective opening area of an intake passage is mechanically opened and closed by a throttle valve. The present invention provides a fuel increasing device capable of suppressing the leaning of the air-fuel mixture during low-speed operation and acceleration operation, and positively and accurately enriching the air-fuel mixture in various operating regions where the air-fuel mixture becomes lean. The purpose is to:

[0009]

According to the fuel increasing device for a carburetor according to the present invention, in order to achieve the above object, a throttle valve for mechanically controlling opening and closing of an effective opening area of an intake passage penetrating a carburetor body. And mechanically compresses the accelerating fuel pump chamber in conjunction with the venturi section formed in the intake passage and the opening operation of the throttle valve, and accelerates the fuel in the accelerating fuel pump chamber into the intake passage through the accelerating fuel discharge passage. A carburetor having an acceleration pump device for injecting and supplying, and a fuel inflow supplied to a valve seat opened in a float chamber of the carburetor by pressurizing fuel stored in a fuel tank by a fuel head difference or a fuel pump. A fuel supply passage, one end of which is connected to the fuel inflow passage, and the other end of which is connected to the intake passage of the carburetor including the intake pipe; a rotation sensor disposed in the fuel increase passage, which detects the engine speed; More engine side intake Alternatively, the output of a pressure sensor for detecting a negative pressure in the intake pipe (negative pressure in the intake pipe) connected to the engine and the control signal from a control circuit to which the fuel increase passage is opened and closed and the fuel flowing in the fuel increase passage are controlled. A control valve for controlling the amount of fuel, wherein the control of the amount of fuel in the fuel increasing passage by the control valve is determined within a predetermined range of rotation of the engine and within the range of rotation. In the range of the negative pressure in the intake pipe, when the rotational speed is constant, the fuel amount is reduced in accordance with the increase in the negative pressure in the intake pipe, and when the rotational speed is increasing, the negative pressure in the intake pipe is reduced. It is characterized in that the fuel amount is reduced according to the rise.

[0010]

When the rotational speed is within a predetermined range of rotation and within a predetermined range of negative pressure in the intake pipe within the above-mentioned range of rotation, the negative pressure in the intake pipe is maintained when the rotational speed is constant. The energization time Ti is shortened in accordance with the rise to increase the fuel
When the vehicle speed is increasing, the energizing time Ti is shortened in accordance with the increase of the negative pressure in the intake pipe to reduce the amount of fuel supplied from the fuel supply passage 20 to the intake path 2. The amount of fuel supplied to is reduced.

[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. In this embodiment,
It is an example 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 disposed in the sliding valve guide cylinder 3, and the throttle valve 9 rotates with respect to the carburetor body 1. An operation shaft 10 is mechanically connected to a freely-supported operation shaft 10 by a link, a lever, or the like, and an operation lever 12 is integrally attached to a shaft end of the operation shaft protruding outside the carburetor body 1. The operation lever 12 is provided with an accelerator wire (not shown) towed by the driver. 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, and the like, and the throttle valve 9 opens and closes the intake passage 2. become. 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. A liquid surface having substantially the same height as a constant liquid surface formed in the float chamber 5 is formed in the acceleration well W, and a main air passage communicating with the atmosphere is formed in the acceleration well W above the liquid surface. Open. (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 rotation sensor for detecting the rotation speed of the engine equipped with the carburetor. Reference numeral 28 denotes an intake passage 2 on the engine side (right side in FIG. 1) from the throttle valve 9 or an intake pipe connected to the engine (both are shown in the drawing). The pressure sensor is a pressure sensor that detects a negative pressure (negative pressure in the intake pipe) within the pressure sensor. For example, the pressure sensor includes a pressure conversion element and a hybrid IC that amplifies an output signal of the conversion element. Is a silicon diaphragm type utilizing the piezoresistive effect. A vacuum chamber is provided on one side of the silicon diaphragm, and the other side is connected to the intake passage 2 on the engine side from the throttle valve 9 via the negative pressure introducing passage 29 or the engine. Induces negative pressure in the tube. 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 rotation sensor 27 and the pressure sensor 28 are input to a control circuit 30 to determine the number of revolutions of the engine and the negative pressure in the intake passage from the throttle valve 9 or in the intake pipe connected to the engine. At the control circuit 30 from the control valve 21
Is output. An example of the above-described predetermined conditions of the engine speed and the negative pressure in the intake pipe at which the control signal for driving the control valve 21 is output from the control circuit 30 is as follows. When the engine speed is 3000 RPM to 9000 RPM, A control signal for driving the control valve 21 is output from the control circuit 30 to the control valve 21 within the range and within the range of the negative pressure in the intake pipe which is within the range of the predetermined number of revolutions. More specifically, the negative pressure in the intake pipe is in the range of -3 mmHg to -200 mmHg when the engine speed (hereinafter simply referred to as "rotation speed") is 3000 RPM, and the negative pressure in the intake passage is -3 mmHg to -12 mmHg when the engine speed is 6000 RPM. -9 m from -3 mmHg at 8000 RPM
mHg range. The condition range is clearly shown in the outline of 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 above condition.

A special feature here is that the control circuit 30
A control signal output from the control valve 21 to the control valve 21 is a drive pulse having a conduction time Ti, and the number of rotations is within a predetermined range of rotation, and within a predetermined range of rotation, the predetermined negative pressure in the intake pipe. Within the range, when the rotational speed is constant, the energization time Ti is shortened in accordance with the increase in the negative pressure in the intake pipe to reduce the amount of fuel supplied from the fuel increasing passage 20 to the intake path 2. When the vehicle speed is increasing, the amount of fuel supplied from the fuel increasing passage 20 toward the intake passage 2 is reduced by shortening the energizing time Ti in accordance with the increase in the negative pressure in the intake pipe. In FIG. 2, the mesh area has the largest amount of fuel supplied from the control valve 21 (referred to as a large flow rate), the solid line hatched area has the largest amount of fuel after the mesh area (referred to as a medium flow rate), and the dotted line hatched area. The amount of fuel in the range is larger than the solid line hatched range (referred to as small flow rate). According to the above, for example, when the rotation speed is 3000R
In the constant rotation state of PM, the negative pressure in the intake pipe is -3m.
In the range of mHg to -10 mmHg, a large flow rate fuel increase correction is performed, in the range of the negative pressure in the intake pipe from -10 mmHg to -30 mmHg, a medium flow rate fuel increase correction is performed, and in the range of the negative pressure in the intake pipe of -30 mmHg to -20
In the range of 0 mmHg, a small flow rate fuel increase correction is performed.

Next, an outline of the operation will be described. First,
A low opening operation state in which the opening of the throttle valve 9 is relatively low (for example, 3/8 opening or less) will be described. In the low opening operation, the venturi portion 11 is small by the throttle valve 9. The opening area is narrowed, and the air flow velocity flowing through the venturi portion 11 of the small opening is increased, and the negative pressure of the venturi portion 11 and the intake passage 2 downstream from the venturi portion 11 is increased and maintained, so that the main fuel Appropriate fuel is sucked into the venturi section 11 and the intake passage 2 from the needle jet 14 as a system and a bypass hole and a pilot outlet hole as a low-speed fuel system (not shown), and supplied to the engine. Is maintained at a relatively low rotation in accordance with the low opening of the motor, and a desired low-speed operation can be performed. According to this, since the rotation speed is 3000 RPM or less and out of the predetermined rotation speed range, the output from the rotation sensor 27 to the control circuit 30 is not made,
A control signal for driving is not output from the control circuit 30 to the control valve 21. 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.

Next, the throttle valve 9 is further opened from the low opening operation state (the opening degree of the throttle valve 9 is not more than 3/8 opening degree). An operation state in which the load is applied to the engine with a small load or a medium load will be described.
In such an operating state, the throttle valve 9 is opened to a medium or high opening degree, the load applied to the engine is not relatively large, and the rotation speed of the engine is properly adjusted in accordance with the opening degree of the throttle valve 9. As a result, the flow velocity of the air flowing through the venturi section 11 increases, and the negative pressure of the venturi section 11 rises sufficiently, and appropriate fuel corresponding to the negative pressure is sucked into the intake passage 2 from the needle jet 14. . More specifically, referring to FIG. 2, when the rotation speed is 3000 RPM, the negative pressure in the intake pipe exceeds -200 mmHg and the rotation speed is 60 rpm.
At 00 RPM, the negative pressure in the intake pipe exceeds -12 mmHg, and at 8000 RPM, the negative pressure in the intake pipe is-
Exceeds 9 mmHg. That is, in such an operation state, the negative pressure in the intake pipe with respect to the rotation speed shown in FIG. 2 rises to a negative pressure outside the outline range. Therefore, the control signal for driving is not output from the control circuit 30 to the control valve 21 because the pressure sensor 28 does not output the control signal to the control circuit 30, and the control valve 21 closes and holds the fuel increasing passage 20. It is. As described above, while the throttle valve 9 is in the high opening operation and the load applied to the engine is small and in the middle load operation, the fuel is not increased from the fuel increasing passage 20 as described above. Since the negative pressure in the venturi section 11 rises sufficiently, appropriate fuel is drawn into the venturi section 11 from the needle jet 14 as the main fuel system and supplied to the engine, thereby satisfying the operation of the engine. A high-speed operation can be obtained according to the degree desired.

On the other hand, although the throttle valve 9 is opened to a medium or high opening degree (for example, the opening degree of the throttle valve 9 is opened by 3/8 or more), the vehicle speed is changed according to the opening degree of the throttle valve 9. This is the case where it does not rise sufficiently. Such a state is a state in which the throttle valve 9 is opened to a medium or high opening degree and a high load is applied to the engine. For example, this state corresponds to a state in which a steep hill is climbed or a load is fully loaded. In this state, the throttle valve 9 is in the middle,
The engine is opened to a high degree of opening, while the rotational speed of the engine decreases due to the application of a high load, the flow velocity of the air flowing through the venturi section 11 also decreases, and the negative pressure of the venturi section 11 decreases. That is, the amount of fuel sucked from the needle jet 14 into the intake passage 2 decreases, the mixture becomes lean, the increase in the engine speed is hindered, and the throttle valve opening becomes appropriate. I cannot get the vehicle speed. The fact that the vehicle speed that is appropriate for the throttle valve opening cannot be obtained in this way means that an appropriate rotational speed cannot be obtained for the throttle valve opening. It is not possible to obtain a negative pressure in the intake pipe. 2, the negative pressure in the intake pipe is -200 mmHg or less when the rotational speed is 3000 RPM, and the negative pressure in the intake pipe is -12 mmHg when the rotational speed is 6000 RPM.
g, and the negative pressure in the intake pipe becomes -9 mmHg or less at a rotation speed of 8000 RPM. When such a state is reached, the rotation speed is detected by the rotation 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 and its output is sent to the control circuit 30. Is entered.

When the outputs from the rotation sensor 27 and the pressure sensor 28 are input to the control circuit 30, the control circuit 30 outputs 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 by the movable iron core 23 being 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. In combination with the fuel sucked into the venturi section 11 from the needle jet 14 as a set, the throttle valve 9 is prevented from being diluted during the high-load operation in which the throttle valve 9 is opened at a medium or high opening, and the engine speed is reduced. The vehicle speed rises to an appropriate vehicle speed according to the throttle valve opening by the increase in the number of revolutions. The supply of the increased fuel from the fuel increasing passage 20 into the intake passage 2 is performed within a predetermined rotational speed range and a predetermined intake pipe negative pressure range (in other words, with respect to the throttle valve opening degree. (At an appropriate rotation speed (vehicle speed)). In FIG. 2, if one example is explained, the rotation speed is 300
At 0 RPM, -3 mmHg to -200 mmHg
At a rotation speed of 6000 RPM, a range from -3 mmHg to -12 mmHg, and at a rotation speed of 8000 RPM, from -3 mmHg to-
The range is up to 9 mmHg. When the rotation speed rises and falls outside the predetermined rotation speed range, or when the rotation speed falls within the predetermined rotation speed range and falls outside the predetermined negative pressure range of the intake pipe, In other words, if the rotation speed (vehicle speed) rises to an appropriate value for the throttle valve opening degree), either one or both conditions are met,
The output of the control signal from the control circuit 30 for driving the control valve 21 is stopped, and the control valve 21 returns to the original position, closes the valve seat 26 by the valve portion 25, and thereby the intake air from the fuel increasing passage 20 The fuel supply to the road 2 is stopped. In FIG. 2, if an example is explained, the number of rotations is 90
When it exceeds 00 RPM, when the rotational speed is out of the negative pressure range of -3 mmHg to -200 mmHg at 3000 RPM, when the rotational speed is out of the negative pressure range of -3 mmHg to -12 mmHg at 6000 RPM, -3m at 8000 RPM
This is when the pressure falls outside the negative pressure range in the intake pipe from mHg to −9 mmHg.

Also, the throttle valve 9 is in an accelerated 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, the rotation speed is low and the vehicle speed is 50 km / h. It is in a low speed condition that cannot be reached sometimes. From 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 engine speed is idling rotation (for example, 1200 RPM) or 3000 RP.
The vehicle speed is low at a low rotation of M or less. In this state, the fuel is sucked into the intake passage 2 mainly from a low-speed fuel system (not shown) such as a bypass hole and a pilot outlet hole, and the engine is operated at a low opening degree and at a low speed. Next, when the throttle valve 9 is rapidly opened to the middle and high opening degrees 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. Road 2
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 through the needle jet 14 because the negative pressure of the intake passage applied to the opening of the needle jet 14 temporarily increases slightly, This is because there is no restriction on the inflow by the fuel jet 16 and the fuel is already stored in the acceleration well W downstream of the main fuel jet 16 and is easily sucked out. However, acceleration well W
Since the fuel stored in the accelerating well W is also limited by the suction of the fuel inside, the engine speed is greatly increased and the vehicle speed is not greatly increased. That is, even if the throttle valve 9 is opened to a middle or high opening degree, it is difficult to immediately increase the rotation speed, that is, the vehicle speed according to the throttle valve opening degree. By increasing the capacity of the acceleration well W, it is possible to increase the rotation speed during acceleration and 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 9 is opened to a medium opening and a high opening from a low opening, and the rotation is slightly increased by the fuel in the accelerating well W, and the predetermined rotation speed is increased. (Not that the rotation speed (vehicle speed) has risen properly according to the throttle valve opening) and that the rotation speed of the engine does not increase sufficiently in the above-mentioned rotation state. The output of the rotation sensor 27 and the output of the pressure sensor 28 are included in the range of the negative pressure in the intake pipe, and the output of the rotation sensor 27 and the pressure sensor 28 which detect the negative pressure (not that the negative pressure in the intake pipe is appropriately increased according to the throttle valve opening). 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 increasing passage 20
A more pressurized fuel is injected and supplied into the intake passage 2, which suppresses the leaning of the air-fuel mixture during the acceleration operation and effectively increases the rotation during the acceleration operation. It can accelerate and rise to rotation (vehicle speed) according to the opening. In response to the supply of fuel from the fuel increasing passage 20, the engine speed is sufficiently increased, the vehicle speed is appropriately increased according to the throttle valve opening, and the intake pipe negative pressure at the engine speed is sufficiently increased. When it rises, the output of the control signal from the control circuit 30 to the control valve 21 is stopped, and the supply of fuel from the fuel increasing passage 20 is cut off. However, the engine speed is changed according to the throttle valve opening. Needle jet 14 as main fuel system
Therefore, the fuel suitable for the high opening operation in the throttle valve 9 is supplied from the needle jet 14 to the intake passage 2 through the throttle valve 9.
It could be sucked into. The acceleration operation described above will be described with reference to a specific example with reference to FIG. 2. When the throttle valve 9 is at a low opening of 2/8 and the rotational speed is 2000 RPM, the throttle valve 9 is quickly opened at a 4/8 opening. 4,000 rpm and the negative pressure in the intake pipe is -8 m
If the pressure becomes mHg (the throttle valve 9 is opened to the intermediate opening degree, but the rotation speed rises only to 4000 RPM), the rotation sensor 27 and the pressure sensor 28 detect this state, and these sensors 27, 28 Output of control circuit 3
0, 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 accelerated to the vehicle speed corresponding to the throttle valve opening. When the rotation speed rises to 5000 RPM according to the throttle valve opening due to the increase in the rotation and the negative pressure in the intake pipe exceeds -17 mmHg (the throttle valve 9 is held at 4/8 opening, The output from the pressure sensor 28 to the control circuit 30 is stopped (at a rotational speed of 5000 RPM, from -3 mmHg to-).
The pressure sensor 28 outputs the control signal to the control circuit 30 within the range of the negative pressure in the intake pipe of 17 mmHg. Is stopped.

In addition, even during an intermediate acceleration operation in which the throttle valve 9 is rapidly opened from the 4/8 opening to the 6/8 opening, the negative pressure in the venturi section 11 does not increase immediately.
In some cases, the increase in the number of revolutions is suppressed and the vehicle speed does not increase to the desired speed. In such a state, the control valve 21 performs the above operation by the signal output from the control circuit 30 to improve the intermediate acceleration operation. Can be planned. FIG.
A more specific example will be described.
8. Revolution speed 5000 RPM, negative pressure in intake pipe -30mm
Assuming that the throttle valve 9 is rapidly opened to a high opening of 6/8 from the Hg throttle valve intermediate opening operation, the rotation speed becomes 6000 RPM, and the negative pressure in the intake pipe becomes -5 mmHg, The rotation speed increased only up to 6000 RPM.) The rotation sensor 27 and the pressure sensor 28 detected this state, and the outputs of the sensors 27 and 28 were input to the control circuit 30. A signal for driving the control valve 21 is output from the control circuit 30. According to this, the fuel is immediately supplied from the fuel increasing passage 20 toward the intake passage 2, the leanness of the air-fuel mixture is suppressed, the rotation of the engine is increased, and the vehicle speed can be accelerated to a vehicle speed corresponding to the throttle valve opening. And
Due to the increase in the rotation, the rotation speed increases to 7000 RPM according to the throttle valve opening, and the negative pressure in the intake pipe decreases by -1.
When the pressure exceeds 0 mmHg (the throttle valve 9 is held at the 6/8 opening and the negative pressure in the intake pipe increases due to the increase in rotation), the output from the pressure sensor 28 to the control circuit 30 is stopped (rotation speed 7000 RPM). At -3mmH
The output from the control circuit 30 to the control valve 21 is stopped by the pressure sensor 28 outputting to the control circuit 30 within the range of the negative pressure in the intake pipe from g to -10 mmHg. The supply of fuel is stopped.

The above is an outline of the operation of the present invention. In the present invention, in particular, the control signal output from the control circuit 30 to the control valve 21 is a drive pulse having the energizing time Ti, and the number of rotations is determined. And within the range of the negative pressure in the intake pipe determined within the above-mentioned range of rotation, when the rotational speed is constant, the energizing time Ti is shortened in accordance with the rise in the negative pressure in the intake pipe. Therefore, the amount of fuel supplied from the fuel increasing passage 20 toward the intake passage 2 is reduced. On the other hand, when the vehicle speed is increasing, the energizing time Ti is increased according to the increase in the negative pressure in the intake pipe.
And the amount of fuel supplied from the fuel increasing passage 20 toward the intake passage 2 is reduced. This state is clearly shown in FIG. 2. In FIG. 2, the amount of fuel supplied from the control valve 21 is the largest in the mesh range (referred to as a large flow rate), and the amount of fuel in the hatched range indicated by a solid line is the second largest ( The fuel amount in the hatched area indicated by the dotted line is larger than that in the hatched area indicated by the solid line (referred to as the small flow rate). According to the above, for example, the rotation speed is 3000 RPM
In a constant rotation state, the negative pressure in the intake pipe is -3 mmH
g to -10 mmHg, a large flow rate fuel increase correction is performed, and the negative pressure in the intake pipe from -10 mmHg to-
In the range of 30 mmHg, the medium flow rate fuel increase correction is performed, and the negative pressure in the intake pipe is changed from −30 mmHg to −200 m.
In the range of mHg, a fuel increase correction of a small flow rate is performed. According to this, a large amount of fuel increase correction is performed as it becomes difficult to suck the fuel from the venturi section 11 into the intake passage 2 due to a decrease in the negative pressure in the intake pipe (the negative pressure decreases). The supplied air-fuel mixture is properly controlled, which has a great effect in terms of engine operability, emission of harmful exhaust gas, and fuel economy. Such an operation state occurs when the load applied to the engine changes at a constant vehicle speed (the rotation speed is constant). As the load increases, the negative pressure in the intake pipe decreases and the load decreases. As a result, the negative pressure in the intake pipe increases. Thus, as the load increases, the amount of fuel supplied from the fuel increasing passage 20 can be increased, so that high load operation can be properly handled. (In other words, as the load becomes smaller, the amount of fuel supplied from the fuel increasing passage 20 can be reduced, and it is possible to appropriately cope with low-load operation.)

Further, it is possible to further improve the accelerated driving performance of the engine. For example, when considering the acceleration operation of an engine in which the throttle valve 9 is rapidly opened to a medium opening and a high opening from a low opening, as described above, the throttle valve 9 is at a low opening and the rotation speed is 2000 RPM. When the throttle valve 9 is rapidly opened from the state to an intermediate opening of 4/8 and the rotation speed becomes 4000 RPM and the negative pressure in the intake pipe becomes -8 mmHg, a signal for driving the control valve 21 from the control circuit 30. According to this, fuel is supplied to the intake passage 2 from the fuel increasing passage 20, the rotational speed is accelerated to 5000 RPM according to the throttle valve opening, and when the negative pressure in the intake pipe exceeds -17 mmHg, the fuel is increased. The supply of fuel from the increasing amount passage 20 toward the intake path 2 is stopped. When the rotation speed is increased from 4000 RPM to 5000 RPM, the negative pressure in the intake pipe is increased from -8 mmHg to more than -17 mmHg.
When the negative pressure in the intake pipe increases from mHg to −17 mmHg, the fuel supplied from the fuel increasing passage 20 into the intake path 2 is supplied with a medium flow rate of fuel in the initial stage, and the rotational speed and the negative pressure in the intake pipe are reduced. It can automatically decrease to a small flow rate as it rises. It is preferable to decrease the supply of fuel from the fuel increasing passage 20 as the acceleration progresses, because the negative pressure in the intake passage increases as the acceleration progresses and the suction of the fuel from the needle jet 14 increases.
As described above, an appropriate fuel correction can be performed for the acceleration operation of the engine, so that the acceleration operability can be further improved.

Further, 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.

[0028]

As described above, the fuel increase device for a carburetor according to the present invention has the following effects. The control of the fuel amount in the fuel increasing passage by the control valve is performed in a state where the rotational speed is constant within the range of the predetermined rotational speed and within the range of the negative pressure in the intake pipe within the range of the rotational speed. According to the fact that the fuel amount was reduced in response to the increase in the intake pipe negative pressure and the fuel amount was reduced in accordance with the intake pipe During medium or high opening operation, the fuel pressurized from the fuel increasing passage can be supplied positively without depending on the negative pressure of the venturi section to suppress the leaning of the air-fuel mixture.
The leanness of the air-fuel mixture during acceleration operation can be suppressed, and the fuel control characteristics of the carburetor can be accurately matched to the engine requirements within a very short period of time. Significant improvement in development efficiency was achieved.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating an example of a range in which an output for driving is output from a control circuit to a control valve in a relationship between an engine speed and a negative pressure in an intake pipe.

[Explanation of symbols]

 2 intake path 5 float chamber 6 valve seat 9 throttle valve 11 venturi section 14 needle jet 17 fuel inflow path 20 fuel increase path 21 control valve 27 rotation sensor 28 pressure sensor 30 control circuit 31 pressure regulator T fuel tank P fuel pump J control jet

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-151551 (JP, A) JP-A-3-151550 (JP, A) JP-A-61-229964 (JP, A) JP-A-59-229 155557 (JP, A) JP-A-57-198343 (JP, A) JP-A-51-116327 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02M 7/12 F02D 45 / 00 362 F02D 45/00 364 F02M 9/06

Claims (1)

(57) [Claims] 1. A throttle valve for mechanically controlling the effective opening area of an intake passage penetrating a carburetor body, a venturi formed in the intake passage, and mechanically in conjunction with an opening operation of the throttle valve. A carburetor having an acceleration pump device that compresses the acceleration fuel pump chamber and supplies the accelerated fuel in the acceleration fuel pump chamber to the intake path via the acceleration fuel discharge path, and the fuel stored in the fuel tank. A fuel inflow passage that is pressurized by a fuel head difference or a fuel pump and is supplied to a valve seat that opens into the float chamber of the carburetor, and has one end connected to the fuel inflow passage and the other end connected to the intake passage of the carburetor including the intake pipe. A fuel increasing passage connected thereto, a rotation sensor arranged in the fuel increasing passage for detecting the number of revolutions of the engine, and detecting a negative pressure in the intake passage connected to the engine from the throttle valve or an intake pipe connected to the engine (negative pressure in the intake pipe). Output of pressure sensor and And a control valve for controlling opening and closing of the fuel increasing passage and controlling the amount of fuel flowing through the fuel increasing passage according to a control signal from a control circuit input thereto. When the engine speed is within a predetermined rotation range and the engine rotation speed is within the predetermined rotation range, and the engine rotation speed is within the predetermined rotation range, the engine rotation speed is constant. A fuel increasing device for a carburetor, characterized in that the fuel amount is reduced in accordance with the increase in the negative pressure and the fuel amount is reduced in accordance with the increase in the negative pressure in the intake pipe when the rotational speed is increasing.