JPH0247590B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a carburetor for supplying a mixture of fuel and air to an internal combustion engine, particularly an internal combustion engine for automobiles, and which has an annular variable ventilator. Regarding.

[Background Art] In a vaporizer having a variable annular vent ule, the vent ule is usually formed between an annular orifice and a cone, and the area of the vent ule is changed by moving the cone in its axial direction. However, since the air bleed mechanism installed in such a carburetor used to uniformly mix air into the fuel sucked out to the orifice using the negative pressure generated by the ventilate, the air-fuel ratio Many methods were required for control. To this end, the present inventor proposed in Japanese Patent Application No. 1983-44795 a system in which the amount of air for air bleed is adjusted according to the negative pressure generated in the intake manifold, but this is equipped with an annular orifice. It did not fully take advantage of the characteristics of the carburetor, and there was a problem in making the air-fuel mixture even.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to adjust the mixture ratio of air and fuel according to the state of the internal combustion engine even in the primary mixing in the air bleed mechanism. Therefore, it is an object of the present invention to provide a carburetor in which the air-fuel ratio can be easily controlled, and the mixture of fuel and air is further improved in uniformity.

[Disclosure of the Invention] Accordingly, the present invention provides a throat portion in a housing having a cylindrical air passage passing through the upper and lower sides, a throat portion protruding into the air passage, and an annular orifice opening at the inner peripheral edge of the throat portion. This carburetor is equipped with a throttle cone that is coaxial with the engine and reciprocally movable in the vertical and axial directions to form an annular variable ventilary between the throat and the throat. It is equipped with an air valve that controls the amount of air for primary mixing in accordance with the intake manifold negative pressure. It is characterized by being mixed with the fuel flowing out from the many micro holes formed in the pipe, and the amount of bleed air in the air bleed mechanism can be controlled according to the negative pressure value of the intake manifold. At the same time, fuel is supplied to the annular orifice from an annular fuel pipe surrounding the orifice.

The present invention will be described in detail below based on the illustrated embodiment. The carburetor shown here has a cylindrical air passage that penetrates vertically and a throat portion that protrudes into this air passage and narrows the cross-sectional area of this air passage. 2 and an annular orifice 4 that opens at the inner circumferential edge of the throat portion 2.
A throttle cone 3 forming an annular variable ventilary is provided between the housing 1 and the housing 1, and a float chamber 8 integrally formed on the side surface of the housing 1
is provided. A cone 3 having a substantially conical outer shape is disposed in the center of the housing 1 so as to be movable in the vertical and axial directions. In between, an annular ventilary is formed. An annular orifice 4 communicating with the float chamber 8 is formed at the minimum inner diameter portion of the throat portion 2 to be open all the way around the entire circumference, and flows down the ventilate between the throat portion 2 and the cone 3. Fuel is sucked out into the air passage through the annular orifice 4 by the negative pressure generated by the air flow. The cone 3 moves downward when the accelerator pedal is depressed in response to the accelerator pedal, and is also sucked and driven downward by the negative pressure in the negative pressure chamber 7 communicating with the intake manifold. This downward movement causes the cone 3 to increase the area of the ventilate.

To explain in more detail, the housing 1 is formed from an upper housing 11 and a lower housing 12. An air cleaner 13 is connected above the upper housing 11, and the lower housing 12 is connected to an air cleaner 13.
An intake manifold is connected to the lower part of the intake manifold via a base 69. The throat portion 2 includes an upper throat portion 21 that integrally projects inward at a lower portion of the inner surface of the upper housing 11, and a lower housing 12.
The annular orifice 4 and the annular expansion chamber 20 located on the outer periphery of the orifice 4 are composed of a lower throat portion 22 integrally projecting inward from the upper inner surface of the upper throat portion 21.
an upper housing 11 and a lower throat portion 2 having
2, and an annular ring 25 for controlling flow rate located between the annular orifice 4 and the expansion chamber 20 located on the outer periphery of the annular orifice 4.
are arranged. Further, the upper throat portion 21 has an inner diameter that becomes smaller as it goes downward, and the lower throat portion 22 has an inner diameter that becomes smaller as it goes upward. The cross-sectional area of the air passage is smallest at the opening.

Next, the fuel path from the float chamber 8 to the orifice 4 will be explained. A total of three fuel paths are provided. The main fuel path is provided in the side wall of the float chamber 8, and its lower end communicates with the inside of the float chamber 8 via the fuel hole 16 and the needle valve 17 shown in FIG. The fuel passage 15 is connected to an annular fuel pipe 19 arranged in the expansion chamber 20 of the fuel passage 15, and the fuel sent through this fuel passage 15 is because the fuel pipe 19 is provided with many micro holes. It is sucked out from this microhole by the negative pressure of the ventilator, passes through the narrow groove 26 formed in the annular ring 25, and then reaches the orifice 4. Here, the thin groove 26 provided in the annular ring 25 that partitions the gap between the upper housing 11 and the lower housing 12 into the orifice 4 side and the expansion chamber 20 side and communicates between them is the fifth Annual ring 2 as shown in the figure
A plurality of grooves are formed at equal intervals so as to cross the lower surface of the groove 5 in a diagonal direction that intersects the diameter direction at approximately 60 degrees, so that the flow passing through the narrow groove 26 at high speed forms a spiral toward the center. A screw 27 for adjusting the flow rate protrudes within the narrow groove 26.

Among the other two fuel paths provided as a power fuel system, one is a power fuel supply system 60 provided in the side wall of the float chamber 8, which is connected to the negative pressure value in the intake manifold. A power piston 61 that is biased downward by a spring and moves up and down in response to
3 and a valve portion including a valve spring 64 and the like, and communicates the fuel passage 15 with the inside of the float chamber 8 through the valve portion and the fuel hole 65. Note that a needle valve 66 shown in FIG. 7 is provided between the valve portion and the fuel passage 15. It is configured so that the amount of fuel sent to the main fuel path can be further increased. The other power fuel supply system 70 is connected to the accelerator shaft 35 by a linkage 74 and supplies additional fuel to the expansion chamber 20 through a valve 71 that is opened and closed in response to throttle operation, as shown in FIG. As shown in the figure, it consists of a fuel tube 72 whose lower end is inserted into the float chamber 8 and the valve 71, and a jet 73 is provided at the opening to the expansion chamber 20. valve 71
opens when the throttle is fully opened.
Note that 75 in the figure is an air pipe that connects the upper space of the float chamber 8 with the outside. Furthermore, this carburetor is actually provided with an accelerator pump, but this is not shown.

The cone 3 is fixed to the upper end of a shaft 31 that is slidably supported in the axial direction by a support 30 that is press-fitted into the lower end opening of the lower housing 12. The inside of the skirt 32, which is located between the upper outer circumferential surface of the support 30 and a minute gap, is a negative pressure chamber 7, and a spring 33 provided in this negative pressure chamber 7.
The cone 3 is urged upward, and the lower end of the shaft 31 is connected to the accelerator shaft 35 via a link 36 and a link 37. As is clear from FIG. 8, the link 36 is fixed to the accelerator shaft 35, whereas the link 37, which is made up of two members, is freely rotatably attached to the accelerator shaft 35. , a pin 38 provided in the link 36 is slidably engaged with an arc-shaped elongated hole 39 provided in the link 37.
The rotation of the accelerator shaft 35 causes the cone 3 to move up and down, changing the area of the ventilate. However, the shaft 31 and the cone 3 are connected to the accelerator shaft 35 with some play, and this play is Within this range, the cone 3 moves up and down depending on the negative pressure value in the negative pressure chamber 7 communicating with the intake manifold. Incidentally, since the range of vertical movement of the cone 3 is further restricted by the stopper 80, etc., when the maximum rotation angle of the accelerator shaft 35 is β, the range of the vertical movement of the cone 3 corresponds to the maximum vertical movement range of the link 37. The maximum rotation angle is an angle α smaller than the rotation angle β.

The negative pressure chamber 7 is connected to the intake manifold through the gap between the skirt 32 and the support 30 as described above, and is connected to the intake manifold as shown in FIG. 30
It is connected to the atmosphere via an air passage 10 formed between the housing 1 and the housing 1, and
The amount of communication between the negative pressure chamber 7 and the atmosphere via the air passage 10 is controlled by a control valve 9. This control valve 9 is provided in the upper housing 11 and is connected to the accelerator shaft 35 by a link mechanism 40, and is fully opened when the accelerator is released and narrows the amount of communication when the accelerator is depressed. It's something that I'm gradually getting used to.

Next, the air bleed mechanism will be explained. This air bleed mechanism also has a main air bleed mechanism 41 and a second air bleed mechanism 42. First, the main air bleed mechanism 41 will be explained. As shown in FIGS. 1
3, the air is heated by heat exchange with the high-temperature exhaust gas of the internal combustion engine, and room temperature air that has passed through the air cleaner 13 is supplied. It's hot,
An air supply path 44 leading from a heat exchange section between the air passing through the air cleaner 13 and the high-temperature exhaust gas to the expansion chamber 20, a vacuum unit 45 connected to the intake manifold, and an air supply path 44 provided midway through the air supply path 44. An air valve 47 is connected via a rod 46 to a diaphragm provided as one wall of the negative pressure chamber in the vacuum unit 45, one end of which is open on the upper surface of the housing 1, and the other end of which is connected to the air supply path. 44, a second air supply path 48 that is connected to the front stage of the air valve 47 and sends room-temperature air after passing through the air cleaner 13 to the air supply path 44; and a second air supply path 48.
The air valve 47 is configured with a needle valve 49 shown in FIG. When the negative pressure inside the intake manifold is small, the air valve 47 is throttled to limit the amount of air sent into the expansion chamber 20. The air thus sent from the main air bleed mechanism 41 to the expansion chamber 20 mixes with the fuel sucked out from the fuel pipe 19 in the expansion chamber 20 by the negative pressure in the ventilate, thereby performing air bleed. The purpose of supplying heated air through heat exchange with high-temperature exhaust gas is to prevent icing, improve the vaporization of the fuel, and ensure good mixing of fuel and air. The reason why heated air and room temperature air can be mixed is that the temperature of the air sent into the expansion chamber 20 can be maintained at a constant temperature of 42 to 45 degrees Celsius. It's for a reason. Although the air valve 47 and the control valve 9 are disposed on the same axis, the two operate separately.

As shown in FIG. 4, the second air bleed mechanism 42 includes a piston valve 56, a valve seat 57, and a valve spring 58, which are spring-biased upward to move up and down according to the negative pressure value in the intake manifold.
One end is open on the upper surface of the housing 1 and the other end is connected from the expansion chamber 20 to the orifice 4.
The air supply passage 59 is opened and closed midway through the intake manifold, and the air supply passage 59 is opened and closed by a valve section according to the negative pressure value in the intake manifold, and air is supplied to the orifice 4 according to the amount of opening and closing. It is supplied to the previous stage.

As is clear from the above description, this carburetor not only controls the vertical movement of the cone 3 together with the throttle by the negative pressure inside the intake manifold, but also controls the power fuel supply system 60, the main air bleed mechanism 41, and the second air It also controls the operation of the bleed mechanism 42. As shown in FIG. 1, a thermal valve 5 is provided in the middle of a negative pressure pipe 50 connecting these and the intake manifold. This thermal valve 5 opens when the temperature of the cooling water of the internal combustion engine exceeds a predetermined value, and communicates the inside of the intake manifold with each of the above-mentioned systems. 41 and the second air bleed mechanism 42,
It does not operate until after the internal combustion engine has almost completely warmed up.

However, to explain the operation of the carburetor, the fuel passes through the fuel passage 15 under the negative pressure generated by the air flow flowing down the ventilate, is mixed with air by the air bleed, and then reaches the orifice 4. is mixed with the flowing air and sent to the internal combustion engine. When the throttle is opened, that is, when the cone 3 is moved downward, the area of the ventilate increases and a large amount of air-fuel mixture is supplied.Also, when the negative pressure inside the intake manifold increases, the negative pressure chamber 7 When the negative pressure increases and the suction force due to this negative pressure becomes greater than the biasing force of the spring 33, the cone 3 moves downward within a predetermined range independently of the movement of the accelerator shaft 35, and draws a large amount of air-fuel mixture. supply. Since there is an air passage 10 communicating with the atmosphere, the negative pressure value of the negative pressure chamber 7 at this time is determined by the control valve 9.
The control valve 9 is connected to the accelerator shaft 35, and when the throttle is returned, the control valve 9 opens fully, and when the throttle is opened, the control valve 9 opens completely. Since the cone 9 is being narrowed down, the vertical position of the cone 3 is determined by both the opening degree of the throttle and the negative pressure in the intake manifold, which is controlled by the opening degree of the throttle. That is,
When idling or returning the throttle,
Since the control valve 9 is fully open and the same amount of air as is sucked out from the negative pressure chamber 7 to the intake manifold is sent to the negative pressure chamber 7 through the air passage 10, the negative pressure chamber 7 becomes negative. There is no pressure and the cone 3 is at its upper limit position. When the accelerator pedal is depressed to open the throttle, the control valve 9 is throttled and the amount of air sent to the negative pressure chamber 7 is smaller than the amount of air sucked out from the negative pressure chamber 7 to the intake manifold. Then, the inside of the negative pressure chamber 7 becomes negative pressure and the cone 3 is sucked downward. As the cone 3 moves downward, the area of the ventilator increases, and as the amount of air flowing down increases, the negative pressure inside the intake manifold decreases, and the amount of air sucked out from the negative pressure chamber 7 to the intake manifold decreases. It becomes less. Therefore, when the amount of air sucked out from the negative pressure chamber 7 and the amount of air sent into the negative pressure chamber 7 through the control valve 9 become equal, the cone 3
is something that stops. If the accelerator is further depressed from this state, the cone 3 will move further down. When the accelerator pedal is released, the control valve 9 rotates in the opening direction, so the amount of air sucked into the negative pressure chamber 7 increases, and the negative pressure in the negative pressure chamber 7 decreases.
The cone 3 moves upward due to the elastic force of the spring 33. Although the cone 3 moves up and down in conjunction with the accelerator shaft 35, it moves in a so-called floating state with respect to the accelerator shaft 35, and the actual control of the ventilate area is controlled by the negative pressure in the intake manifold. is determined by the balance between the two and the throttle opening. In addition, as mentioned above, the link 3 corresponding to the vertical movement of the cone 3
The reason why the maximum rotation angle of 7 is α is that if the cone 3 moves up and down at the idle position, the idle rotation speed will not be stable, and if the cone 3 moves up and down when the throttle is fully open, the power fuel supply system 70 will not operate properly. This is because it becomes stable.

Now, due to the negative pressure generated by the airflow flowing down the ventilator whose area is controlled as described above, fuel is sucked out from the orifice 4 surrounding the annular ventilator, mixed with air, and passed through the intake manifold to the internal combustion engine. The fuel sucked out from this orifice 4 is sent to the engine, and the fuel is primarily mixed with air by air bleed as described above. The main air bleed mechanism 41 mixes air, which is heated by heat exchange with high-temperature exhaust gas and brought to a predetermined temperature by mixing with room temperature air, with fuel, when the internal combustion engine cooling water exceeds a predetermined temperature and closes the thermal valve 5. Since the air valve 47 is activated after opening, and the air valve 47 is closed while the cooling water temperature is low, air bleed air is not sent to the expansion chamber 20. However, after the cooling water temperature exceeds a predetermined temperature and the warming up of the internal combustion engine is almost completed, the air valve 47 controls the amount of air sucked into the expansion chamber 20 according to the negative pressure value in the intake manifold. It is something. That is, when the negative pressure inside the intake manifold is large, the rod 46 of the vacuum unit 45 is retracted and the air valve 47 is opened.
When the accelerator is depressed and the internal combustion engine becomes high speed, the air valve 47 is throttled because the negative pressure in the intake manifold becomes small. In other words, as the internal combustion engine goes from low speed to high speed, the amount of bleed air decreases and the amount of fuel supplied to orifice 4 increases.Conversely, when the accelerator is released and the internal combustion supply changes from high speed to low speed, this Air valve 47 responds to negative pressure changes in the intake manifold during
is opened to increase bleed air. Then, the air-bleed fuel passes through the narrow groove 26 of the annular ring 25 at high speed, is sucked out from the orifice 4 to the vent turret, and is uniformly mixed with the high-speed air flowing down the vent turret.

The second air bleed mechanism 42 is configured such that when engine braking is applied, such as when descending a slope, the negative pressure inside the intake manifold becomes extremely large and the amount of fuel sucked out from the ventilate increases, resulting in poor fuel efficiency and exhaust gas. It was established to solve the problem of extremely large amounts of CO and HC inside.
After the thermal valve 5 opens, when the negative pressure in the intake manifold becomes extremely large, the piston valve 56 descends and the air that has passed through the air cleaner 13 is sent to the front chamber of the orifice 4 through the air supply path 59. In order to reduce the negative pressure in the front chamber, the amount of fuel sucked out to the ventilate is reduced, and the fuel is completely combusted. When the negative pressure inside the intake manifold becomes small, the piston valve 56 moves upward and blocks the air supply path 59.

When an internal combustion engine performs high output and high speed rotation,
A power fuel supply system 60 that operates according to the negative pressure value of the intake manifold operates to supply a rich mixture. That is, when the accelerator pedal is depressed to open the throttle in order to obtain high output, the negative pressure inside the intake manifold becomes smaller and smaller, and the force that pulls up the power piston 61 weakens, so the power piston 61 descends due to the spring bias. to push up the power valve 62. Therefore, the fuel is added to the fuel flowing through the fuel passage 15 through this valve portion, thereby creating an air-fuel mixture with a rich mixture ratio. When a higher output is required, by fully depressing the access button and fully opening the throttle, the valve 71 connected to the accelerator shaft 35 in the mechanical power fuel supply system 70 opens. The fuel is supplied directly to the expansion chamber 20 through the fuel tube 72 and the jet 73 in addition to passing through the above-mentioned flow path, and in addition to the fuel supply from the power fuel supply system 60, the rich air-fuel mixture necessary for high output is supplied. is created.

Furthermore, the embodiment shown in FIG. 9 and FIG.
Although it has the same configuration as the embodiment, the float chamber 8 equipped with the fuel passage 15 and the power fuel supply system 60 and 70 is formed separately from the housing 1, and the two are connected by the fuel tubes 23 and 24. This is an example in which it can be set not only as a downdraft type but also horizontally or diagonally.

[Effects of the Invention] As described above, in the present invention, the mixture ratio can be controlled according to the state of the internal combustion engine even during temporary mixing in which the bleed air is mixed with the fuel, and for this purpose, the air-fuel ratio can be controlled. It is easy to control and contributes to cleaner exhaust gas and reduced fuel consumption, and a large number of micro holes are provided in the annular fuel pipe arranged in an annular expansion chamber surrounding an annular orifice. When the fuel flows out from these micropores, it is mixed with air for air bleed, and the fuel is mixed with the air flowing down the annular ventilate from the annular orifice located on the inner circumferential side of the annular expansion chamber. The fuel that flows out of the annular fuel pipe and is air-bleeded,
Because the fuel is supplied from the entire circumference of the annular air stream flowing down the annular ventilate, the fuel and air are evenly mixed, ensuring that the air-fuel mixture sent to each cylinder of the internal combustion engine is consistent. It is possible.

[Brief explanation of drawings]

FIG. 1 is a plan view of one embodiment of the present invention, FIG. 2 is a cross-sectional view of the same A-O-B, and FIG. 3 is a C-O-
D sectional view, FIG. 4 is an A-OE sectional view of the same as above, FIGS. 7
The figures are a sectional view of a part of the same as above, FIGS. 8a and 8b are longitudinal sectional views and horizontal sectional views showing the connecting part between the accelerator shaft and the cone, and FIG. 9 is a sectional view of another embodiment, FIG. 10 is a plan view of the same float chamber, in which 1 is a housing, 2 is a throat part,
3 is a cone, 4 is an orifice, 5 is a thermal valve, 7 is a negative pressure chamber, 9 is a control valve, and 35 is an accelerator shaft.

Claims (1)

[Claims] 1. A housing having a cylindrical air passage penetrating vertically, a throat part protruding into the air passage, and an annular orifice opening at the inner peripheral edge of the throat part, coaxial with the throat part. The carburetor is equipped with a throttle cone that is arranged to be reciprocally movable in the vertical and axial directions and forms an annular variable ventilary between the carburetor and the throat section, which primarily mixes air with the fuel before the orifice. It is equipped with an air valve that controls the amount of air for air bleed according to the intake manifold negative pressure, and the air for bleed is formed in an annular fuel pipe arranged in an annular expansion chamber surrounding an annular orifice. A carburetor is characterized in that the fuel is mixed with fuel flowing out from a large number of micropores. 2. Claims characterized in that the bleed air is a constant temperature mixture of air that has passed through an air cleaner, heated through heat exchange with high-temperature exhaust air, and unheated air. The vaporizer according to item 1.