JP3196084B2 - 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. Further, 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, so that it is not possible to supply sufficient acceleration fuel. There was fear.

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. A fuel increasing device capable of actively and highly accurately enriching the air-fuel mixture in various operating regions in which the air-fuel mixture becomes lean while suppressing the air-fuel mixture during low-speed operation and acceleration operation. It is intended to provide.

[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 penetrating the carburetor body is mechanically opened and closed by a throttle valve. A carburetor having a venturi portion formed in an intake passage while controlling the fuel; a fuel stored in a fuel tank is pressurized by a fuel head difference or a fuel pump and supplied to a valve seat opened in a float chamber of the carburetor. A fuel inflow passage; one end connected to the fuel inflow passage, and the other end connected to an intake passage of a carburetor including an intake pipe; and an output of a vehicle speed sensor disposed in the fuel increase passage and detecting a speed of the vehicle. The output of a pressure sensor for detecting a negative pressure in the intake pipe connected to the engine or the intake pipe connected to the engine from the throttle valve (negative pressure in the intake pipe). Do A control valve for controlling the amount of fuel flowing through the fuel increasing passage; and controlling the fuel amount in the fuel increasing passage by the control valve within a vehicle speed range where the vehicle speed is determined, and controlling the vehicle speed. When the vehicle speed is constant and the vehicle speed is constant, the fuel amount is reduced in accordance with the increase in the intake pipe negative pressure. The fuel amount is reduced according to the increase in the negative pressure.

[0010]

When the vehicle speed is within a predetermined vehicle speed range and within the vehicle speed range and a predetermined intake pipe negative pressure range, the control valve is operated by a control signal from the control circuit to increase the fuel amount. Open the 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. And
At this time, when the vehicle speed is constant within the range of the intake pipe negative pressure determined within the range of the vehicle speed, the fuel amount is reduced in accordance with the increase of the intake pipe negative pressure, and the vehicle speed is increased. In this case, the fuel amount was reduced in accordance with the rise in the negative pressure in the intake pipe, so that as the load increased, the amount of fuel supplied from the fuel increasing passage could be increased to cope with high load operation, and the engine Appropriate fuel correction can be performed for the acceleration operation.

[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. Incidentally, 31 is a pressure regulator. 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 vehicle speed sensor for detecting the speed (hereinafter referred to as "vehicle speed") of the vehicle on which the engine equipped with the carburetor is mounted. Reference numeral 28 denotes the intake passage 2 on the engine side (right side in FIG. The pressure sensor detects a negative pressure (negative pressure in the intake pipe) in an intake pipe (both not shown) connected to the engine. For example, the pressure sensor includes a pressure conversion element and a hybrid IC that amplifies an output signal of the conversion element. The pressure conversion element is, for example, a silicon diaphragm type using a piezoresistance effect of a semiconductor, and has a vacuum chamber on one side of the silicon diaphragm and an engine side from the throttle valve 9 via the negative pressure introduction path 29 on the other side. To a negative pressure in the intake passage or intake pipe connected to the engine. The negative pressure introduction passage 29 in the present embodiment opens from the throttle valve 9 to the intake passage on the engine side.

Outputs of the vehicle speed sensor 27 and the pressure sensor 28 are input to a control circuit 30. The control circuit 30 determines the vehicle speed and the negative pressure in the intake passage on the engine side from the throttle valve 9 or in the intake pipe connected to the engine. A control signal for driving the control valve 21 is output from 30. The control circuit 30 described above
An example of the determined conditions of the vehicle speed at which the control signal for driving the control valve 21 is output from the vehicle and the negative pressure in the intake pipe is as follows. The vehicle speed is within the range of 50 km / h to 110 km / h, and The control circuit 30 outputs a control signal for driving the control valve 21 to the control valve 21 within the range of the negative pressure in the intake pipe which is within the range of the vehicle speed. More specifically, the negative pressure in the intake pipe is in the range of -3 mmHg to -100 mmHg when the vehicle speed is 50 km / hour, and the negative pressure in the intake pipe is -3 mm when the vehicle speed is 80 km / hour.
Hg to -8 mmHg, and the vehicle speed is 100 km /
At times, the negative pressure in the intake pipe is in the range of -3 mmHg to -4 mmHg. The condition range is clearly shown in FIG. 2, but the condition range is appropriately set at the time of setting operation of the carburetor to the engine, and is not limited to the condition.

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. As a result, the flow velocity of the air flowing through the venturi portion 11 of the small opening is increased, and the intake passage 2 downstream of the venturi portion 11 and the venturi portion 11 is increased.
, The appropriate pressure of the fuel is sucked into the venturi section 11 and the intake passage 2 from the needle jet 14 as the main fuel system and the bypass hole and the pilot outlet hole as the low-speed fuel system (not shown). The throttle valve 9 is operated satisfactorily in accordance with the low opening degree of the throttle valve 9 to obtain a desired relatively low speed (less than 50 km / hour). According to this, since the vehicle speed is less than 50 km / h and out of the predetermined vehicle speed range, the output from the vehicle speed sensor 27 to the control circuit 30 is not made, and the control circuit 30 No control signal for driving is output. Therefore, the control valve 21 is in an inoperative state, and the valve portion 25 of the control valve 21 is
And 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), and the throttle valve 9 is in the middle opening state (the opening degree of the throttle valve 9 is lower). 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 and high opening degree, the load applied to the engine is not relatively large, and the engine speed is appropriately increased. The flow velocity of the air flowing through the ventilator increases, and the negative pressure in 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, and according to the throttle valve opening. A proper vehicle speed can be obtained. An example of the relationship between the vehicle speed and the negative pressure in the intake pipe will be specifically described with reference to FIG. 2. At a vehicle speed of 50 km / h, the negative pressure in the intake pipe exceeds -100 mmHg and the vehicle speed is 8
At 0 km / h, the negative pressure in the intake pipe exceeds -8 mmHg,
At a vehicle speed of 100 km / h, the negative pressure in the intake pipe is -4 mmHg
Exceeds. That is, in such an operating state, the negative pressure in the intake pipe with respect to the vehicle speed shown in FIG. 2 rises to a negative pressure outside the operating range. Therefore, since the pressure sensor 28 does not output the control signal to the control circuit 30, the control signal for the drive is not output from the control circuit 30 to the control valve 21, and the control valve 21 keeps the fuel increasing passage 20 closed. Is what you do. 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, the needle jet 1 as the main fuel system
The appropriate fuel is sucked into the venturi section 11 and supplied to the engine to satisfy the operation of the engine, and a desired medium or high vehicle speed corresponding to the throttle valve opening can be obtained.

On the other hand, despite the fact that 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 depends on 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 inability to obtain an appropriate vehicle speed with respect to the throttle valve opening in this way means that an appropriate rotational speed cannot be obtained with respect to the throttle valve opening. , It is not possible to obtain an appropriate negative pressure in the intake pipe. 2, the negative pressure in the intake pipe is -100 mmHg or less at a vehicle speed of 50 km / h, the negative pressure in the intake pipe is -8 mmHg or less at a vehicle speed of 80 km / h, and the negative pressure in the intake pipe is-at a vehicle speed of 100 km / h.
It becomes 4 mmHg or less. When such a state is reached, the vehicle speed is detected by the vehicle speed sensor 27, and the output thereof is output to the control circuit 30.
On the other hand, the negative pressure in the intake pipe is detected by the pressure sensor 28, and the output is input to the control circuit 30.

When the respective outputs from the vehicle speed 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 at the time of high load operation in which the throttle valve 9 is opened at a medium or high opening to reduce the engine speed. The vehicle speed increases to an appropriate vehicle speed according to the throttle valve opening. The supply of the increased fuel from the fuel increasing passage 20 into the intake passage 2 is performed within a predetermined vehicle speed range and a predetermined intake pipe negative pressure range (in other words, with respect to the throttle valve opening degree). (The vehicle speed has not risen to an appropriate speed). In FIG. 2, if an example is explained, at a vehicle speed of 50 km / h, -3 mmHg to -10
0 mmHg, at a vehicle speed of 80 km / h, from -3 mmHg to -8 mmHg, and at a vehicle speed of 100 km / h, from -3 mmHg to -4 mmHg. Then, when the vehicle speed rises and falls outside the predetermined vehicle speed range, or when the vehicle speed falls outside the predetermined vehicle speed range and falls outside the predetermined negative pressure range of the intake pipe, If the vehicle speed has been increased to an appropriate value with respect to the throttle valve opening degree), the output of the control signal from the control circuit 30 for driving the control valve 21 is stopped, and the control valve Reference numeral 21 denotes a valve which returns to the original position and closes the valve seat 26 with the valve portion 25, thereby stopping the supply of fuel from the fuel increasing passage 20 to the intake passage 2. In FIG. 2, if one example is described, when the vehicle speed exceeds 110 km / h, the vehicle speed becomes 50 kph.
m / h, out of the negative pressure range in the intake pipe from -3 mmHg to -100 mmHg, at a vehicle speed of 80 km / h, out of the negative pressure range in the intake pipe from -3 mmHg to -8 mmHg, and -3 mmHg at 100 km / h From-
This is when the pressure falls outside the negative pressure range in the intake pipe of 4 mmHg.

Also, during the 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 vehicle speed is low, in which the vehicle speed does not reach 50 km / h. It is in. From this state, the driver pulls the accelerator wire to quickly open the throttle valve 9 to the middle and high opening state,
Perform 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. In the state where the throttle valve 9 is in the low opening state, the engine speed keeps the idling rotation (for example, 1200 RPM) or the low rotation, and the vehicle speed is low. 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 in the intake passage 2 is increased at a stretch, and according to this, the negative pressure at the tip of the needle jet 14 opening in the intake passage 2 temporarily increases 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, 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 engine speed is significantly 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, it is difficult to immediately increase the vehicle speed to the vehicle speed corresponding to the opening of the throttle valve. If the capacity in the accelerating well W is increased, it is possible to increase the rotation speed during acceleration and increase the vehicle speed. However, the inner and outer diameters of the mixing nozzle 15 increase the drivability in other operating regions. Inevitably, the capacity of the accelerating well W is
Because it is restricted. 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 increased by the fuel in the acceleration well W,
The vehicle speed is slightly increased and falls within the determined vehicle speed range (it is not that the vehicle speed is properly increased in accordance with the throttle valve opening), and the engine speed is reduced in the vehicle speed state. The vehicle speed sensor 27 and the vehicle speed sensor 27, which detect the negative pressure in the intake pipe by detecting that the negative pressure is not included in the intake pipe and is included in a predetermined range of the negative pressure in the intake pipe (not that the negative pressure in the intake pipe is appropriately increased according to the throttle valve opening) The output of the pressure sensor 28 is the control circuit 3
0, and 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. This suppresses leaning of the air and effectively increases the rotation during the acceleration operation. The vehicle can accelerate to a vehicle speed corresponding to the throttle valve opening. In response to the supply of fuel from the fuel increasing passage 20, the engine speed sufficiently increases, the vehicle speed appropriately increases in accordance with the throttle valve opening, and the negative pressure in the intake pipe at the vehicle speed sufficiently increases. Then, 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.
Since a large negative pressure acts on the needle jet 14 as the main fuel system because the engine speed is sufficiently increased and the vehicle speed is appropriately increased according to the throttle valve opening, the throttle valve 9 The fuel suitable for high opening operation can be sucked into the intake passage 2 from the needle jet 14. The above-described acceleration operation 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, the throttle valve 9 is quickly moved to 4/8 from a state where the vehicle speed is 30 km / hour. If it is assumed that the throttle valve 9 is opened to the middle opening degree and the vehicle speed rises only to 60 km / h, the throttle valve 9 is opened to the middle opening degree, and the vehicle speed is 60 km / h and the negative pressure in the intake pipe becomes -10 mmHg. That is, the vehicle speed sensor 27 and the pressure sensor 28 detect this state, the outputs of the sensors 27 and 28 are 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 increase passage 2
From 0, fuel is immediately supplied to the intake passage 2, the mixture is prevented from being lean, and the rotation of the engine is increased to accelerate to a vehicle speed corresponding to the throttle valve opening. When the rotation speed increases, the vehicle speed increases at 70 km / h according to the throttle valve opening, and when the negative pressure in the intake pipe exceeds -13 mmHg (the throttle valve 9 is held at 4/8 opening, and The output from the pressure sensor 28 to the control circuit 30 is stopped (at a vehicle speed of 70 km / h, the output from -3 mmHg to -13 mm).
The pressure sensor 28 outputs a signal to the control circuit 30 within the range of the negative pressure in the intake pipe of Hg.
From 0, the output 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.

Further, 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. The throttle valve 9 is quickly opened to a high opening of 6/8 opening from the throttle valve intermediate opening operation at a vehicle speed of 70 km / h and a negative pressure of -20 mmHg in the intake pipe, and the load in the intake pipe is reduced at a vehicle speed of 80 km / h. If the pressure becomes -6 mmHg (the throttle valve 9 was opened to 6/8 but the vehicle speed increased only to 80 km / h), the vehicle speed sensor 27 and the pressure sensor 28 detect this condition and The output of the sensors 27 and 28 is
, And 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 path 2, the lean mixture is suppressed, the engine speed is increased, and the vehicle speed can be accelerated to the vehicle speed corresponding to the throttle valve opening. . When the rotation increases, the vehicle speed increases by 90 km / h according to the throttle valve opening, and when the negative pressure in the intake pipe exceeds -6 mmHg (the throttle valve 9 is maintained at 6/8 opening and the rotation increases. The output from the pressure sensor 28 to the control circuit 30 is stopped (vehicle speed 90 km / h).
At this time, the pressure sensor 28 outputs to the control circuit 30 within the range of the negative pressure in the intake pipe of -3 mmHg to -6 mmHg), whereby the output from the control circuit 30 to the control valve 21 is stopped. The supply of fuel to the intake path 2 is stopped.

The above is an outline of the operation of the present invention. In the present invention, the control signal output from the control circuit 30 to the control valve 21 is used as a drive pulse for the energization time Ti, and the vehicle speed is controlled at a predetermined vehicle speed. Within the range and within the range of the negative pressure in the intake pipe defined within the range of the vehicle speed; when the vehicle speed is constant, the energizing time Ti is shortened in accordance with the increase in the negative pressure in the intake pipe to increase the fuel. The amount of fuel supplied from the fuel increase passage 20 toward the intake passage 2 is reduced. On the other hand, when the vehicle speed is increasing, the energization time Ti is shortened in accordance with the increase in the negative pressure in the intake pipe, and the fuel supply passage The fuel amount supplied toward the intake passage 2 is reduced. Such a state is clearly indicated by oblique lines in FIG. 2. In FIG. 2, the mesh amount is the largest in the amount of fuel supplied from the control valve 21 (referred to as a large flow rate). The amount of fuel is large (referred to as medium flow rate), and the amount of fuel in the hatched area indicated by the dotted line is larger than that indicated by the solid line (referred to as small flow rate). According to the above, for example, the vehicle speed is 50 km
At a constant vehicle speed of / h, a large flow rate fuel increase correction is performed in the range of the negative pressure in the intake pipe from -3 mmHg to -10 mmHg, and the negative pressure in the intake pipe is reduced from -10 mmHg to -30 mmHg.
The fuel increase correction of the medium flow rate is performed in the range of g, and the fuel increase correction of the small flow rate is performed in the range of the negative pressure in the intake pipe of −30 mmHg to −100 mmHg. 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 operating state occurs when the load applied to the engine changes while the engine speed is constant (vehicle speed is constant). As the load increases, the negative pressure in the intake pipe decreases, and the load decreases. , 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 middle opening and a high opening from a low opening, as described above, the throttle valve 9 is a low opening and the vehicle speed is 30 km.
/ Hour state, the throttle valve 9 is opened and the vehicle speed becomes 6
When the negative pressure in the intake pipe becomes -10 mmHg at 0 km / hour, a signal for driving the control valve 21 is output from the control circuit 30, whereby fuel is supplied to the intake passage 2 from the fuel increasing passage 20 and the engine And the vehicle speed is increased to 70 km / h according to the throttle valve opening, and the acceleration is completed. When the vehicle speed increases from 60 km / h to 70 km / h, the negative pressure in the intake pipe increases from −10 mmHg to −13 mmHg, but from −10 mmHg to −13 mmHg.
When the negative pressure in the intake pipe rises up to mmHg, the fuel supplied from the fuel increasing passage 20 into the intake path 2 is supplied with an intermediate flow rate of fuel in the initial stage, and decreases to a small flow rate as the vehicle speed and the negative pressure in the intake pipe increase. And can be automatically reduced. The reason that the supply of fuel from the fuel increasing passage 20 can be reduced as the acceleration proceeds as described above is because the negative pressure in the intake pipe increases as the acceleration progresses and the suction of fuel from the needle jet 14 increases. As described above, more appropriate fuel correction can be performed for the acceleration operation of the engine, so that the acceleration driving performance can be further improved.

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.

[0027]

As described above, the fuel increase device for a carburetor according to the present invention has the following effects. In a carburetor that mechanically controls opening and closing of the effective opening area of the intake passage by a throttle valve, in a range where the vehicle speed is determined, and in a range of the negative pressure in the intake pipe determined in the range of the vehicle speed, When the vehicle speed is constant and the amount of fuel is reduced according to the increase in the intake pipe negative pressure, and when the vehicle speed is increasing, the fuel amount is reduced according to the increase in the intake pipe negative pressure. During high-opening operation of the valve, etc., the fuel pressurized from the fuel increasing passage is actively supplied without depending on the negative pressure of the venturi section, and it is possible to suppress the leaning of the air-fuel mixture and accelerate. It is possible to suppress the leaning of the air-fuel mixture during operation, and in particular, the fuel control characteristics of the carburetor can be exactly matched to the engine requirements within a very short time, thereby significantly improving the engine performance. Open with We were able to achieve a significant improvement in efficiency.

[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 showing 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 a vehicle speed 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 T fuel tank P fuel pump J control jet

Continuation of the front page (58) Field surveyed (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 carburetor in which an effective opening area of an intake passage penetrating through a carburetor body is mechanically controlled by a throttle valve to open and close and a venturi portion is formed in the intake passage; and fuel stored in a fuel tank. A fuel inflow through a fuel head difference or a fuel pump to supply to a valve seat that opens into the float chamber of the carburetor; one end of which is connected to the fuel inflow passage, and the other end of which is an intake of the carburetor including an intake pipe. A fuel increasing passage connected to the road; an output of a vehicle speed sensor arranged in the fuel increasing passage and detecting a speed of the vehicle, and a negative pressure in the intake pipe on the engine side from the throttle valve or in the intake pipe connected to the engine (negative pressure in the intake pipe). And 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 the pressure sensor detects the output. The control of the fuel amount in the fuel increasing passage by the valve is performed such that the vehicle speed is kept constant within the range of the vehicle speed in which the vehicle speed is determined, and within the range of the negative pressure in the intake pipe defined in the range of the vehicle speed. A fuel increasing device for a carburetor, wherein the fuel amount is reduced in accordance with an increase in the intake pipe negative pressure and the fuel amount is reduced in accordance with an increase in the intake pipe negative pressure when the vehicle speed is increasing.