JPS62267554A - Slide throttle valve type carburetter - Google Patents

Abstract

PURPOSE:To improve low speed fuel consumption, by a method wherein fuel is fed to a low speed system route by first opening only an auxiliary intake air passage, and fuel is fed to a main system route by secondly opening a main intake air passage by means of a slide throttle valve which simultaneously opens and closes the main intake air passage and the auxiliary intake air passage, which are positioned in parallel. CONSTITUTION:A small auxiliary intake air passage 24 is installed in parallel to a main intake air passage 2, fuel is fed to the main intake air passage 2 through a main nozzle 15, and fuel is fed to the auxiliary intake air passage 24 through a low speed nozzle 23a independently from each other. In a throttle valve 4, sliding at right angles with each intake air passage, only the auxiliary intake air passage 24 is opened during the primary stage of upward movement, and fuel is stably fed to the low speed system route. When the throttle valve 4 is further moved upward, the main intake air passage 2 is also opened, and fuel is fed through the main nozzle 15.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a manual throttle valve type carburetor, and in particular to a sliding throttle valve carburetor that can improve stability at low speeds in high-output, high-speed engines. Regarding a throttle valve type carburetor.

<Conventional technology> For engines that emphasize high output and high rotation, it is possible to satisfy high-speed performance by using a carburetor with a large-diameter intake duct. There is a disadvantage that the venturi flow velocity decreases and the air-fuel mixture tends to become too lean. As a carburetor that can correct these inconveniences and exhibit good engine performance over a wide operating range, we have developed a composite carburetor that has multiple intake ducts.
Alternatively, a throttle valve type carburetor is known, which changes the venturi diameter depending on the operating conditions of the engine. Conventionally, the structure was relatively simple, and it was made into a small light village with a weight of 1q.
Therefore, a stratified throttle valve type carburetor is generally used as a carburetor for two-wheeled vehicles.

On the other hand, the fuel supply path in the carburetor is roughly divided into the low-speed system and the main system, but in the low-speed rotation range including the idle link, the edge of the throttle valve is close to the inner wall of the intake duct when it is closed. Generally, it is operated by fuel supplied through a pilot outlet or bypass port provided in the section where the engine is operated.

<Problems to be Solved by the Invention> Incidentally, even in the variable venturi type carburetor using a locally operated throttle valve as described above, the fuel discharge ports for the low-speed system and the main system are provided in the same intake path, unlike the conventional method. In the vaporizer of
Since the diameter of the intake duct connected to the engine's intake port is too large for the intake flow rate when the throttle valve is slightly opened, the fuel tends to flow into the pipe wall, making it difficult to promote sufficient atomization. There is this inconvenience. Particularly in the case of engines for vehicles such as two-wheeled vehicles, where there is a strong demand for miniaturization, the length of the intake duct must be shortened as much as possible, which is a major constraint in terms of improving atomization efficiency. be.

In view of the disadvantages of the prior art, the main object of the present invention is to suitably promote atomization of fuel during low-speed rotations including idling, and to improve the stability of low-speed engine rotations. An object of the present invention is to provide a habitual throttle valve type carburetor.

<Means for Solving the Problems> According to the present invention, this purpose is achieved by providing an air intake path connected to an intake port of an engine, and an air intake path that crosses the intake path! A single-acting throttle valve type carburetor is provided with a single-acting throttle valve that forms a variable venturi by changing its behavior, and has separate fuel supply paths for a main system and a low-speed system, wherein the intake path consists of a large-diameter main intake path and a small-diameter sub-intake path that are parallel to each other, the main system fuel supply path communicates with the main intake path, and the low-speed system fuel supply path communicates with the sub-intake path. 1 and a dynamic throttle valve, characterized in that the throttle valve is adapted to open the auxiliary intake passage before the main intake passage from a state in which the throttle valve simultaneously closes both intake passages. This is achieved by providing a type vaporizer.

<Function> In this way, if fuel is supplied only from the small-diameter auxiliary intake passage when the throttle valve is opened at a small opening that causes idling, sufficient mixing can be achieved even during low-speed rotation with low suction pressure. It becomes possible to increase the flow rate of air, and an improvement in atomization efficiency can be achieved.

Especially the main +? ? By opening both J intake passages in stages using a common throttle valve, it is possible to smooth the connection between the low-speed system and the main system without complicating the structure.

Embodiments The present invention will now be described in detail with reference to specific embodiments with reference to the accompanying drawings.

FIG. 1 shows the entire variable venturi type carburetor according to the present invention, and inside the carburetor body 1, there is provided a main intake passage 2 extending in the left-right direction in FIG. . The main intake passage 2 has an air horn 2a at its upstream end along the intake direction A that smoothly curves and widens toward the upstream side, and is connected to an air cleaner (not shown) to introduce clean air. It is being done.

A guide groove 3 is recessed approximately in the center of the main intake passage 2 in a direction approximately perpendicular to the intake flow line, and inside the guide groove 3,
A throttle valve 4 which can open and close the main intake passage 2 with a pair of partition plates 4a and 4b is provided so as to be movable. The throttle valve 4 is remotely operated via a throttle lever (not shown) by engagement with a connecting mechanism 6 provided on a throttle shaft 5 rotatably mounted on the carburetor body 1. There is.

A vacuum piston 7 having a rectangular cross section is disposed between a pair of partition plates 4a and 4b of the throttle valve 4.
along the same sliding axis! It is set up so that it can move. From this vacuum piston 7, a hollow connecting rod 8 whose one end is fixed to the vacuum piston 7 is connected.
extends upwardly along one movement axis of the vacuum piston 7.

The upper opening of the carburetor main body 1 is closed by a cover member 9, and between the opening and the cover member 9 there is an outer peripheral portion of a diaphragm 10 in the shape of a circular film made of a rubber material or the like. are sandwiched, and a negative pressure chamber 11 is formed on the inner surface of the cover member 9.
An atmosphere i1a is defined inside the vaporizer main body 1.

A diaphragm retainer 12 is fixed to the center of the diaphragm 10, and the above-mentioned connecting rod 8 is attached to the center of the diaphragm retainer 12.
The other end is fixed. As mentioned above, the connecting rod 8 is hollow, and the pressure in the main intake passage 2 is introduced into the negative pressure chamber 11 through the negative pressure introduction hole (not shown) bored in the lower part of the vacuum piston 7. It is made possible to do so. Also,
Between the cover member 9 and the diaphragm retainer 12,
A compression coil spring 13 is compressed and constantly urges the vacuum piston 7 downward via the connecting rod 8.

A variable venturi portion 14 is constructed between the lower end of the vacuum piston 7 and the inner wall of the main intake passage 2 facing thereto, and the venturi negative pressure is transferred to the negative pressure chamber 11 as described above.
The vacuum piston 7 can be raised in response to an increase in venturi negative pressure.

A main fuel nozzle 15 is provided inside the main intake passage 2 facing the variable venturi portion 14, and a tapered jet needle 16 is inserted into the nozzle 15. The jet needle 16 is connected to the vacuum piston 7 described above, and is configured to be able to move in and out of the main fuel nozzle 15 according to the movement of the vacuum piston 7, thereby responding to an increase or decrease in the diameter of the variable venturi portion 14. By changing the jet diameter of the main fuel nozzle 15, the amount of fuel discharged is automatically adjusted to 1q.

An air bleed pipe 17 is connected to the middle part of the main fuel nozzle 15 from diagonally below. The end of the air bleed pipe 17 is connected to a float chamber 18 formed in the lower part of the carburetor main body 1.
A main fuel jet 19 is formed at the open end of the main fuel jet 19 to meter the fuel flow. The air bleed pipe 17 has a large number of small holes, and mixes the air and fuel introduced from the main air guide passage formed inside the carburetor body 1, and sends the emulsified mixture to the main fuel nozzle. Send on 15th.

Inside the float chamber 18, a slow jet 20 and a pistar jet 21 are installed approximately parallel to the main fuel jet 19.
are arranged side by side. Both these jets 20.2
1 has an air bleed pipe similar to the main fuel jet 19, and mixes air into the fuel. The slow jet 20 communicates with low-speed fuel discharge ports including a bypass port 23a provided immediately before the downstream partition plate 4b, and the pistar jet 21 communicates with the intake passage 2 of the carburetor body 1. It communicates with the bista valve 25 provided on the upper side, and supplies a rich mixture for starting, which will be described later, into the auxiliary intake passage 24 together with the atmosphere introduced from the bista air introduction passage 35. Furthermore, a float 22 is swingably suspended inside the float chamber 18, and works in conjunction with a float valve (not shown) to keep the fuel level constant at all times.

As also shown in FIG. 2, the above-mentioned sub-intake path 24 is provided diagonally below the main air-intake path 2 and parallel to the main air-intake path 2. This auxiliary intake passage 24 branches from the main intake passage 2 at the variable venturi portion 14, and the throttle valve 4
The opening and opening of the main intake passage 2 can be opened and closed by a partition plate 4b on the downstream side of the main intake passage 2. Furthermore, as shown in FIG. 2, the positional relationship between both intake passages 2.24 and the downstream partition plate 4b is such that the sub-intake a24 begins to open first as shown by the imaginary line a, and As shown, the openings of both intake passages 2.24 are defined to partially overlap and open. Incidentally, when the vacuum piston 7 is at its lowest position, the variable venturi portion 14 is formed with a primary venturi having a predetermined opening area.

As clearly shown in FIGS. 3 and 4, the connecting plug 8 extending upward from the vacuum piston 7 has a hole bored in the center of the connecting portion 4C formed on the upper side of the throttle valve 4. 4d relatively loosely. There is a gap 7 between the upper part of the vacuum piston 7 and the outer peripheral surface of the connecting plug 8.
a is formed. Inside the gap 7a, a leak valve 50 having a cylindrical shape with different diameters that can slide on the outer circumferential surface of the connecting plug 8 is fitted with the inner circumferential surface of the small diameter portion 50a of the leak valve 1.
Further, a gap is formed between the inner circumferential surface of the large diameter portion 50b and the outer circumferential surface of the connecting plug 8.

The leak valve 50 is always urged upward by a coil spring 51 that is contracted to surround the connecting plug 8, and when no external force is applied, the large diameter portion 50 is closed as shown in FIG.
The inner step portion 50C of b comes into contact with an O-ring 52 fitted to the connecting plug 8 and is bent. The connecting plug 8 is also provided with a leak passage 53, and when the inner step 50C of the leak valve 50 comes into contact with the O-ring 52 as described above, this leak passage 53 is closed and the venturi When the pressure is led to negative pressure 11 and the upper end of the leak valve 50 and the upper end of the vacuum piston 7 both contact the lower surface of the connecting portion 4C of the throttle valve 4, as shown in FIG. This leak passage 53 is opened so that the negative pressure 11 and the atmosphere i1a can communicate with each other.

Next, the air-fuel mixture supply path will be explained mainly with reference to FIG.

Near the connection part with the air horn 2a at the upstream end of the main intake passage 2, a jet 3 is inserted into the atmosphere ffi'la inside the carburetor main body 1.
The port 31a of the first main air introduction passage 31, which communicates with the bleed passage 39 which introduces bleed air into the air bleed pipe 17 of the main fuel jet 19, is open. .

A bista valve 25 that forms a starting fuel supply passage is provided on the side of the carburetor body 1, and the bista valve 25 is connected to a separate drive device (not shown) to control the position of the plunger 32 that opens and moves. Accordingly, atmospheric chamber 1a
and the air horn 2 described above.
The position where the second main air introduction passage 34 which joins the first main air introduction passage 31 from the main air introduction passage 31 from a (FIG. 5) is communicated with, the vice air introduction passage 35 which communicates with the atmospheric chamber 1a when the throttle valve 4 is fully closed, and the pipe A two-way valve that can be switched to a position (FIG. 6) in which the bistor combustion passage 36 communicating with the star jet 21 and the bistor mixture passage 37 communicating with the most downstream side of the sub-intake passage 24 are communicated with each other. It is configured as.

Note that both the first and second main air introduction passages 31.
37I is provided with jets 31b and 34a to appropriately balance the air flow rate.

The low-speed combustion passage 20a through which the emulsified fuel from the slow jet 20 flows is branched in the middle, and one is provided just before the downstream partition plate 4b facing the main and auxiliary intake passages 2.24. The other side is connected to the bypass ports 23a and 23b, and the other side is connected to the bypass port 23a, 23b.
It communicates with a pilot outlet 38 provided with the opening.

A pilot screw 39 is screwed into the pilot outlet 38 so that the idling mixture ratio can be adjusted from the outside of the carburetor main body 1.

Next, the operation of the above embodiment will be explained with reference to FIGS. 7 to 9.

As shown in FIG. 1, at the time of starting, the throttle valve 4 is closed, and by the action of the pistar valve 25, rich starting mixture is supplied from the auxiliary intake passage 24 via the bistar mixture passage 37 to the engine (not shown). is delivered towards the suction port of the

When the throttle valve 4 is opened while the Paista valve 25 is in operation (at the position shown in FIG. 6), the throttle valve 4 closes the Vista air introduction passage 35 as shown in FIG. aisle 3
4 is blocked, the main bleed air is restricted, and both the bistor mixture and the main mixture become rich, which compensates for the enrichment during cold cooling and prevents the engine from running out of breath.

Push in the Paista valve 25 to the position shown in Figure 5.
The bistor system passages 35.21.37 are closed and the main air passages 33.34 are in communication. In this state, the main bleed air flows through the first Macer air introduction passage 31 and the second
Air bleed pipe from both main air introduction passage 34
7 will be introduced. When the throttle opening is low, where there is almost no pressure difference between the internal pressure of the atmosphere 1a and the air horn 2a, the first,
An appropriate amount of bleed air is supplied from both second main air introduction passages 31,34.

During high-speed rotation when the air horn 2a tends to have negative pressure,
Depending on the pressure difference between the first main air introduction passage 31 and the second main air introduction passage 34, the second main air introduction passage 34
Bleed air leaks into the first main air introduction passage 31, and as a result, the mixture ratio of the air-fuel mixture discharged from the main nozzle 15 is corrected to the rich side. The balance of the air ports from both Mayshare introduction passages 31 and 34 may be appropriately set depending on the diameters of the jets 31b and 34a provided in both roads.

During idling, fuel metered by the slow jet 20 is supplied from the pilot outlet 38 provided in the auxiliary intake passage 24, and the idling is controlled according to the throttle opening on the auxiliary intake passage 24 side and the pushing range of the pilot screw 39. Driving takes place.

When the throttle valve 4 is slightly opened, the degree of opening on the side of the auxiliary intake passage 24 increases, and fuel is also sucked out from the bypass port 23b on the side of the auxiliary intake passage 24 due to the negative pressure at the edge of the downstream partition plate 4b. The amount of fuel supplied from the sub-intake passage 24 increases. Further, the main intake passage 2 communicates with the intake passage 24, and fuel is also sucked out from the bypass port 23a provided directly downstream of the main fuel nozzle 15 (Fig. 7). ).

As shown in FIG. 7, when the throttle valve 4 and the vacuum piston 7 are operating together, a so-called cutter is formed between the upstream partition plate 4a and the lower surface of the vacuum piston 7. way is formed and the main nozzle 15
By adjusting the negative pressure acting on the bypass port 23a and the bypass port 23a, it is possible to suitably control the mixture concentration at a low opening degree.

When the throttle valve 4 is opened beyond the primary pendulum diameter formed at the lowest position of the vacuum piston 7, fuel is sucked from the main fuel nozzle 15.

Furthermore, as the throttle valve 4 opens, the intake flow rate increases, but as a result, the negative pressure on the downstream side of the intake passage decreases, and fuel is no longer sucked out from both bypass ports 1 to 238, 23b and the pilot outlet 38. Gradually, it will be operated only with fuel from the main fuel nozzle 15.

On the other hand, as the throttle valve 4 is opened, the leak valve 50
is closed (FIG. 4), and the venturi negative pressure acts on the negative pressure chamber 11 via the negative pressure passage inside the connecting culm 8. As a result, the vacuum piston 7 rises to a position where the weight related to the vacuum piston, the downward force due to the coil spring 13, the atmospheric pressure, and the venturi negative pressure are balanced, and the diameter of the variable venturi portion 14 is determined.

When the vacuum piston 7 rises and the leak valve 50 comes into contact with the throttle valve 4 (FIG. 3), the leak passage 53
opens and the vacuum piston 7 descends. In this way, the vacuum screw 1 is adjusted according to the opening degree of the throttle valve 4.
Hen 7 is activated to maintain proper venturi flow rate. Moreover, due to the leakage passage 53, the vacuum screw 1hen 7
Since the vacuum piston 7 does not generate more lifting force than necessary, and the vacuum piston 7 does not overshoot even with sudden negative pressure fluctuations, an accurate fuel supply amount can be maintained at all times, improving stability in transient conditions. Also improved by 1q. Furthermore,
As shown in Fig. 8, even if the throttle valve 4 is suddenly opened, the vacuum piston 7 will not rise unless the intake tract negative pressure increases sufficiently, so it is possible to prevent the air-fuel mixture from becoming temporarily too lean. , it is possible to perform smooth acceleration without causing any breathing problems. Furthermore, when the engine load suddenly increases and the rotational speed decreases, the engine piston 7 descends to prevent the air-fuel mixture from becoming too lean.

When the throttle valve 4 is fully opened, as shown in FIG. 9, the vacuum piston 7 also closes in accordance with the rotational speed, and in this state, nothing remains on the inner surface of the main intake passage 2 that causes intake resistance. Therefore, extremely high suction efficiency can be obtained.

<Effects of the Invention> As described above, according to the present invention, it is possible to promote fuel atomization during low-speed rotation and stabilize idling rotation, so it is possible to set the idling mixture leaner than before. This has an extremely large effect on improving low-speed fuel efficiency and low-speed drivability.

In addition, even though the intake ducts are separate systems, it is extremely easy to connect the two using a common sliding throttle valve.
It is also effective in smoothing the connection of the fuel supply route between the low-speed system and the main system, and improving the engine operating characteristics over the entire rotation range.

[Brief explanation of drawings]

FIG. 1 is a general cross-sectional side view of a vaporizer according to the invention. FIG. 2 is a schematic view along the line ■-■ in FIG. 1. 3 and 4 are enlarged sectional views showing details of the sliding throttle valve portion. FIG. 5 is a schematic development view showing the air-fuel mixture supply path. FIG. 6 is an explanatory diagram of the operation of the bista valve. 7 to 9 are explanatory views of the operation of the throttle valve and the vacuum piston. 1... Carburetor main body 1a... Atmospheric chamber 2... Main intake n 2a... Air horn 3... Guide groove 4... Throttle valve 4a... Upstream side partition plate 4b... Downstream Side partition plate 4C...Connection part
5... Throttle shaft 6... Connection mechanism 7...
・Vacuum piston 7a...Gap 8...
・Connection culm 9...Cover member 10...Diaphragm 11...Negative pressure chamber 12...Diaphragm retainer 13...Compression coil spring 14...Variable venturi portion 15...Main fuel nozzle 16 ... Jet needle 17 ... Air bleed pipe 18 ... Float to 19.
...Main fuel jet 20...Slow jet 20a...Low speed fuel passage 2
1... Paista jet 22... Float 23a, 23b... Bypass port 24... Eye open airway, 25... Paista valve 30... Atmospheric passage 30a... Jet 31.
...First main air passage 31a...Port 31b...Jet 32.
...Plunger 33...Atmospheric introduction passage 34...
Second main air introduction passage 34a...Jet 35...Pie square introduction passage 36...Vista fuel passage 37...Vista mixture passage 38...Pilot outlet 39...Bleeder passage 50...Leak Valve 50a... Small diameter part 50b.
・Large diameter portion 50c ・Stepped portion 51 ・Coil spring 52 ・O ring 53 ・Leak passage patent Applicant: Honda Motor Co., Ltd. Representative Patent attorney: Yo Oshima - 1st Figure pressure Figure 2 Q-, -, =-1-no Figure 7 Figure 8

Claims (3)

[Claims] (1) It is equipped with an intake passage connected to the intake port of the engine, a sliding throttle valve that forms a variable venturi by sliding across the intake passage, and separate fuel systems for the main system and low-speed system. A sliding throttle valve type carburetor having a supply path, the intake path consisting of a large-diameter main intake path and a small-diameter sub-intake path that are parallel to each other, and the main system fuel supply to the main intake path. the low-speed system fuel supply path communicates with the sub-intake passage, and the sub-intake passage precedes the main intake passage from the state in which the throttle valve simultaneously blocks both intake passages. A sliding throttle valve type carburetor, characterized in that the carburetor is configured to be opened by opening. (2) The sliding throttle valve type carburetor according to claim 1, wherein the sub-intake passage is branched from the venturi portion. (3) The low-speed system fuel supply path has a pilot outlet and a plurality of bypass ports, one bypass port is provided in the main intake path, and the other bypass port and the pilot outlet are provided in the sub-intake path. A sliding throttle valve type carburetor according to claim 1 or 2, characterized in that the sliding throttle valve type carburetor is provided with: