JPS60113055A - Carburettor - Google Patents

Abstract

PURPOSE:To obtain an optimum air-fuel ratio and as well to miniaturize a carburettor, by sliding a piston having a metering needle and provided in one side of the carburettor, under venturi-vacuum. CONSTITUTION:Negative pressure from a negative pressure take-out part 22b which is formed in an invariable venturi 3 downstream of a choke valve 5 is introduced through a passage 22 into a space above a piston 8 which is lidable in a chamber 7 formed in one side part of a carburettor body 1. The piston 8 is pushed downward under the balance between upper and lower springs 9, 10, and a needle 14 adapted to be inserted into a metering jet is secured to the lower section of the piston 8 by means of a retaining spring 17. When the throttle valve 6 is opened to increase the amount of intake-air, the negative pressure of the venturi 3 is increased, resulting in the upward movement of the piston 8, and therefore, the needle 14 is moved upward by a height (1), thereby optimum fuel is fed from the venturi 3 through a nozzle 19a in a passage 19.

Description

[Detailed description of the invention] B. Industrial application field The present invention relates to a vaporizer.

Conventionally, in a carburetor, a variable venturi type carburetor and an air valve type carburetor are used to change the flow area of the main fuel passage in order to discharge and supply main fuel fak into the intake cylinder according to the amount of intake air. There is. As is well known, the variable venturi type carburetor has a metering needle (V) fixed to the suction piston, which is inserted into the main jet provided in the intake cylinder, and the suction piston is moved forward and backward by negative pressure caused by changes in the amount of intake air. This changes the annular area formed by the metering needle and the main jet to match the main fuel discharge amount to the intake air amount. In this variable venturi type carburetor, the amount of movement of the suction piston is directly reflected in the change in the discharge amount of the main fuel. Since the ratio between the main jet and the main jet does not necessarily match, it may not be possible to change the opening area of the main jet to match changes in the amount of intake air, and it is not always possible to adjust the main fuel to the amount of intake air. In addition, since the metering needle is fixed to the suction piston and the main jet is screwed to the suction cylinder, the main fuel discharge amount can be adjusted by changing the taper shape of the metering needle and by screwing the main jet. The only option is to make adjustments, and the adjustment range cannot be wide enough. Furthermore, when the intake negative pressure pulsates due to engine operation, the suction piston moves and directly changes the opening amount of the main jet, resulting in a problem of changing the air-fuel ratio.

In addition, as is well known in the air pulp type vaporizer, a metering needle is connected to the air valve. , the metering needle) V is inserted into the main jet, and the metering needle) V is moved forward and backward by the operation of an air valve that opens and closes according to the amount of intake air, thereby changing the annular area composed of the meter link needle and the main jet. , the amount of intake air is adjusted by the amount of main fuel discharged. Therefore, this air valve type carburetor has the same problems as the variable venturi type carburetor described above, and the installation position of the air valve must be incorporated into the electrifier because it needs to be linked with the metering needle. Therefore, the overall height of the carburetor becomes high, and if the air valve is installed near the upstream of the venturi, the flow of intake air will be biased to one side in the venturi and slot repal 1 part depending on the opening of the air valve, so the mixture guided to the intake manifold will be There is also the problem that the air-fuel ratio of the air-fuel mixture becomes non-uniform throughout the entire flow, and the air-fuel ratio of the air-fuel mixture introduced into each cylinder to the engine becomes non-uniform.

9. Purpose of the Invention In view of the above, the present invention provides a metering needle (V f, mJ) for controlling the opening amount of the main fuel passage R1 by the air valve rev of the variable venturi type carburetor and the air valve rev of the air valve type carburetor. The air needle device (
The object of the present invention is to propose a new type of carburetor that solves the above-mentioned problems by making the long groove and the main fuel metering device 11'4 independent.

29 invention i? G Formation In order to achieve the above object, the first foil light is as follows:
A housing piston cylinder, a housing piston slidably mounted in the housing piston cylinder, a metering needle protruding from the housing piston in the sliding direction thereof, and a metering needle inserted into the housing piston, F) A fuel metering mechanism consisting of a main jet that measures the flow rate of the main fuel passage with an annular area of In addition, the housing piston cylinder is provided with a negative pressure passage that opens into the intake passage, and the negative pressure generated in the core negative pressure passage causes the housing piston to be compressed by the annular area. The second invention is characterized in that the return spring is provided with an adjuster (1'4) for adjusting the spring load. A third invention is characterized in that, in addition to the first invention, a stopper is provided for regulating the amount of movement of the housing piston in a direction in which an annular area for measuring the flow rate of the main fuel is expanded. That is.

E. Embodiments Next, FIGS. 1 to 3, which show embodiments of the first and second inventions, will be explained. (1) is the carburetor body, (2
) is the intake passage, (3) is the vent! J, (4) is the mixing channel t<, (5) is the choke pulp or air pulp, and (6) is the throttle valve. (7)
is a housing piston cylinder; (8) is a housing piston that is slidably disposed within the housing piston cylinder (7); It is provided outside in parallel with the intake passage (4). Inside the housing piston cylinder (7) are a return spring (9) that biases the housing piston (8) downward in the closing direction, and a balance spring that biases the housing piston (8) upward in the opening direction. 00 is provided. Ql) is the upper end of the return spring (9)? The retaining plate holds the cover plate 0 fixed to the housing piston cylinder (7), and can be screwed up and down with an insert pin (
11a), and by moving the retaining plate QD up and down by screwing, the spring load of the return nup ring (9) can be adjusted. 03
is the balance spring θ0 (711 lower end fr: supporting plate, which is fixed at the bottom of the housing piston cylinder (7). α→ is the housing piston (8
) is a metering needle protruding downward in the sliding direction from the lower end of the metering needle, and its upper end loosely penetrates the bottom plate (8a) of the housing piston (8).
8) The lower part of the metering needle Q41 penetrates the support plate 03 and reaches below the oil level in the float chamber uQ. ing.

0 is the bottom plate (8a) of the housing piston (8)
Q71 is a nup ring that presses downward the collar (148) of the metering needle Ivα station.
The shaft is biased to tilt in one direction. 0υ is a fuel intake port of the main fuel passage θ, which is located directly below the metering needle 1v (14) and opens into the float chamber CIQ, and the metering needle 1 is connected to the fuel intake port Q81. The main jet (
1) is installed. The main nozzle (19a) of the main fuel passage o9 is located at a venturi portion (3) formed in the intake passage (2) and opens into the intake passage (2).

Hunger is airbleed. The housing is a negative pressure passage, one end (22a) of which communicates with the upper chamber (7a) of the housing piston cylinder (7), and the other end of which communicates with the negative pressure inlet (22a).
2b) is the venturi part (3) formed in the intake passage (2).
It opens into the intake passage (2). There is a large i in the lower chamber (7b) of the housing piston cylinder (7).
This is an atmospheric passageway for introducing air.・ (F) is a choke pulp (or air pulp) shaft, and a choke spring (C) is wound around this, one end of the choke spring @ is held by the choke lever ■, and the other end is connected to the carburetor body (1) side. 9 The chalk pulp (
5) is biased in the fully closed direction. It is a well-known electrothermal auto choke mechanism, with a bimetal cap, choke lever ring,
Heater C (If&) is used to obtain the chalk pulp effect during cold operation.

When the engine is stopped, the throttle valve (6) is fully closed as shown in Figure 7, and there is no air flow in the intake passage (2), so there is no air in the negative pressure passage. No negative pressure is generated. Therefore, the housing piston (8) is pressed downward by the spring load of the return spring (9) and stops at the illustrated position where it balances with the balance spring (II), and the metering needle 1v (L → ) The annular area of the main fuel passage is also minimized.

Also, the metering needle μα fathom has its tsuba (1aa)
Since one end of the jet is in contact with the tilting protrusion αQ and the other end is pressed by the spring αη, it is tilted as shown in the figure, and its lower metering portion comes into contact with one side of the inner surface of the main jet α). From the engine stop state shown in Fig. 1, as shown in Fig. 2, in a partial load state where the throttle valve (thrower)/repulgue (6) t is slightly opened, the choke pulp (5) is ) opens against the load of the choke spring (c) and the bimetal (2), and stops at the position where this negative pressure and the load are balanced. At the same time, negative pressure generated near the venturi portion (3) acts from the negative pressure intake port (22b) through the negative pressure passage @ into the upper chamber (7a) of the housing piston cylinder (7), and the negative pressure The housing piston (8) is pulled up against the return spring (9) and stopped at a position where the negative pressure matches the load of both springs (9) and αQ. This causes the housing piston (8) to rise to the position shown in Figure 2, and the metering needle/
vQ< also increases by one dimension shown, and the annular area for fuel flow formed by the metering needle α station and the main jet (1) becomes wider than in the state shown in FIG. The main fuel measured by this annular area passes through the main fuel passage Q9, mixes with air from the air bleed Cυ, is discharged from the main nozzle (19a) into the intake passage (2), and is discharged from the throttle valve (6). ) (il- supplied to the engine via

Next, when the throttle valve (6) is further gradually opened, the amount of incoming air gradually increases and the opening degree of the choke pulp (5) also increases, and the opening degree of this choke pulp (5) is equal to the venturi diameter. Or, if it becomes slightly larger, the subsequent amount of incoming air is measured by the venturi section (3). Before metering by the venturi section (3), it functions in the same way as a variable venturi vaporizer, and when it moves to metering by the venturi section, it becomes a fixed venturi vaporizer. This increase in the amount of air flowing into the housing piston cylinder (7
) also increases, the housing piston (8) rises further, and the annular area for fuel flow also increases. Then, as shown in Figure 3, the throttle valve (
6) is fully opened and the amount of incoming air reaches its maximum, the negative pressure in the upper chamber (7a) of the housing piston cylinder (7) also becomes higher, causing the housing piston (8) to be removed from the uppermost position as shown in Figure 3. The metering needle l and α→ are raised by the L dimension from the state shown in FIG. 1 to maximize the annular area for fuel circulation formed by the metering needle α and the main jet blade. That is, the annular area of the main jet increases linearly in proportion to the intake air amount until the throttle valve (6) is fully opened, as shown in FIG. 1(a). In addition, during cooling, the closing force of the yoke pulp increases below the set temperature, similar to the conventional auto choke, so the choke pulp opening becomes smaller and the air-fuel ratio becomes richer even when the engine is warmed up after starting the engine. . In other words, since the choke pulp opening degree is small in the same air flow as during warm-up, the negative pressure in the venturi part (3) is high, and the amount of rise of the housing piston (8) (the amount of rise of the metering needle p) becomes large. This is because if the annular face plate is also large, the amount of fuel discharged from the main nozzle 1v (19a) will be large. The relationship between this amount of air and the negative pressure in the venturi section is shown in FIG. In addition, rotate the insert pin (lla) forward and backward to remove the retaining plate α.
By increasing D, the spring load of the return spring (9) can be changed to 2 or more, and by this change, the timing of the start and end of the movement of the metering needle tv Q4 can be set as desired. That is, the movement of the metering needle α→ can be freely set independently of the amount of intake air in the intake passage (2) and adjusted to the main fuel discharge amount, and the range of adjustment can be increased. Furthermore, dimensional tolerances can be easily accommodated. Additionally, when the negative pressure in the intake passage (2) pulsates due to engine operation, the choke valve (air valve) (5) opens and closes to control the negative pressure. There is little change in the negative pressure in the upper chamber (7a) of the piston cylinder (7). Therefore, such pulsation has little effect on the metering of the main fuel and is less likely to cause changes in the air-fuel ratio. In addition, since the metering needle α is biased at an angle of inclination such that its metering part comes into contact with a part of the inner surface of the main jet, the linearity (inclination angle) of the metering needle αa is The fuel metering indicator turns blue. In addition, since the negative pressure intake (22b) of the negative pressure passage (support) is opened to the venturi part (3), the metering needle +41 is optimal in the entire range from the minimum to the maximum air flow rate. Operate. That is, when the annular area formed by the choke pulp (air valve) (5) and the bore is smaller than the circulation area of the venturi part (3), the negative pressure intake port (22b) is connected to the intake passage (2). There is not much difference in the lift of the metering needle α→ regardless of the position, but the choke pallev (air valve)
When it opens wide and the amount of air is measured by the venturi part (3), it will not be possible to raise the metering needle α0 in proportion to the air flow rate unless the venturi part (3) has the fastest flow velocity. It is.

G. Other Embodiments Next, a third embodiment of the invention shown in FIGS. 3 and 7 will be described. This embodiment uses a nut stopper Qe that regulates the upward movement position of the housing piston (8) in the above embodiment.
The cover plate (2) fixed to the housing piston cylinder (7) is integrally formed, and the other structure is the same as that of the previous embodiment. Structural members similar to those in the embodiment described above will be given the same reference numerals as in the embodiment described above, and a description of their structure and operation will be omitted.

According to this embodiment, by setting the position of the stopper 6 turret as desired, the highest position of the housing piston (8), that is, the metering needle) is formed by the main jet (1) and K. The upper limit of the maximum area of the annular area for fuel metering can be set as desired.

That is, the housing piston (8) rises due to the increase in negative pressure due to the increase in the amount of air flowing into the intake passage (2), but as shown in FIG. 7, when the housing piston (8) comes into contact with the stopper eel Even if the amount of incoming air is further increased thereafter, the raising of the housing piston (8), that is, the increase in the annular area for fuel metering is stopped. In the above embodiment, the main jet is a variable jet in the ridge that reaches the maximum speed, whereas in this embodiment, the main jet is a variable jet in the range above a certain heavy speed, that is, above a certain amount of incoming air as shown in Fig. 1. is a fixed jet with a fixed annular area for fuel metering.

Which of the two examples? Whether or not to use it selectively is determined by the required air-fuel ratio of the engine, but the above-described embodiment is advantageous in the case of a heavy-speed engine. In addition, in this example, the butterfly pin (
The variable jet area and fixed jet area of the main jet can be changed by rotating 11a) in the forward and reverse directions to adjust the nupling load of the return spring (9).

Although each of the embodiments described in OIJ is applied to a single-bore type vaporizer, the invention of the present application can also be applied to a continuous type vaporizer. In addition to the electric heating type shown in the illustrated embodiment, the chalk pulp (5) may be operated in a fully automatic manner using a hot water type, an exhaust type, a wax type, or the like. In addition, the negative pressure outlet (22b) and the main nozzle (19a) were opened flush with the venturi part (3) in the embodiment, but
A set of reso-ispas may be provided that protrudes from the inner surface of the venturi portion (3). Furthermore, the annular area for fuel metering may be adjusted by providing the main jet ω so that it can be moved up and down, and adjusting the annular area according to this movement.

Since the effects of the first invention are as described above, the present invention has an effect similar to that of the present invention.

■ The main fuel metering operation is not done by the movement of the suction piston or air valve as in the past, but is now done based on the negative pressure created by the amount of intake air after being metered by the air valve, etc. There is no need to require high precision in the operation of the suction piston or air valve as in the past, and even if there is variation in the opening of the suction piston or air valve, it can be dealt with by adjusting the fuel metering member such as the metering needle. Therefore, it is not necessary to make the machining accuracy of each part as strict as in the past, and costs can be reduced.

■ Since the main fuel is measured based on the negative pressure caused by the amount of intake air, even if the ratio of the amount of movement of the suction piston or air valve to the amount of intake air does not match, the amount of main fuel discharged can be adjusted. It can be adapted to the amount of intake air. Furthermore, even if the intake pipe negative pressure pulsates due to engine operation and the suction piston or air valve fluctuates, the main fuel metering is less affected and an appropriate air-fuel ratio can be maintained.

■ Since the main fuel metering mechanism and the intake air metering mechanism are separate and independent, the main fuel amount can be adjusted over a wide range.

■ The air valve, which is the intake air metering mechanism, can be formed separately from the main fuel metering mechanism, so by installing the air valve in the path of the air cleaner connector/lid instead of installing it in the carburetor body, the air valve can be discharged from the carburetor. In addition, the overall height of the vaporizer can be lowered by arranging the air valve at a position far away from the venturi part of the carburetor, which eliminates the problems caused by the uneven flow of intake air seen in the conventional structure. It is also possible to prevent inconsistency in the air-fuel ratio to the cylinder.

■ The return spring of the housing piston is equipped with an adjustment mechanism that adjusts its spring load, so this adjustment allows you to adjust the timing of the metering needle I's movement start and end, as well as the main fuel discharge relative to the intake air amount. The amount can be easily adjusted.

■ Since we have provided a nut that regulates the amount of movement of the housing piston in the direction in which the annular area that measures the flow rate of the main fuel expands, the jet in the main fuel metering part is set to 1, and when the speed is below a certain speed, it becomes a variable jet and becomes a variable jet when the speed is above a certain speed. In this case, it can be a fixed jet.

■ If the metering needle is biased to one side within the main jet, the linearity (tilt angle) of the metering needle is good and fuel metering accuracy is good.

(2) By providing the negative pressure intake port in the negative pressure passage in the venturi portion formed in the intake passage, the metering needle can be operated optimally over the entire range from the minimum to the maximum intake air flow rate. Furthermore, by providing the main nozzle for the main fuel in the venturi section at the same position as the negative pressure outlet, it becomes very easy to match the air-fuel ratio.

[Brief explanation of drawings]

Figures 1 to 3 are longitudinal sectional views showing embodiments of the seventh and second inventions, in which Figure 1 shows the engine in a stopped state, Figure 2 shows the state at partial load, and Figure 3 shows the engine at full load. It is the state of the time. Fig. 1 is a characteristic diagram showing the annular area of the main jet section with respect to the intake air quantity, Fig. S is a characteristic diagram showing the venturi negative pressure with respect to the intake air quantity, and Figs. 3 and 7 are examples of the third invention. FIG. 3 shows the engine at a stopped state, and FIG. 7 shows the engine at full load. (1) Carburetor body (2) Intake passage (3) Venturi part (5) Choke pallet (6) - Slot pallet (7) Housing Piston cylinder (8) - housing piston (9) - return spring αQ - balance spring (lla) - 9 insert pins - metering needle H - tilting protrusion 0η - ...Spring 09...Main fuel passage W---Main jet 2...1.Negative pressure passage (22b)...Negative pressure intake country...Stopper Patent applicant Aisan Kogyo Co., Ltd.-2I/73I 741EI,? 5I 6m/? 7m

Claims (1)

[Scope of Claims] 1. A housing piston cylinder, a housing piston slidably provided in the housing piston cylinder, a metering needle 7 protruding from the housing piston in the sliding direction thereof, and the meter. A fuel metering mechanism consisting of a main jet into which a ring needle is inserted and which measures the flow rate of the main fuel passage using the annular area thereof, and a return spring that biases the housing piston in a direction in which the annular area is reduced is installed in the intake passage. A negative pressure passage is provided outside the intake passage that does not interfere with the flow of intake air inside the housing piston cylinder, and the housing piston cylinder is provided with a negative pressure passage that opens into the intake passage. A carburetor characterized in that the annular area is communicated so as to operate in a direction in which the annular area is expanded. 2. A housing piston cylinder, a housing piston slidably provided in the housing piston cylinder, a metering needle protruding from the housing piston in the sliding direction, and a metering needle inserted into the housing piston. A main jet that measures the flow rate of the main fuel passage with an annular area of A negative pressure passage is provided outside the intake passage that does not interfere with the flow, and the housing piston cylinder has a negative pressure passage that opens into the intake passage, and the housing piston and the annular area are expanded by the negative pressure generated in the negative pressure passage. 1. A carburetor, characterized in that said return spring is connected to operate in a direction in which said return spring is operated, and further includes an adjustment mechanism for adjusting said spring load. 3. A housing piston cylinder, a housing piston slidably provided in the housing piston cylinder, a metering needle protruding from the housing piston in the sliding direction thereof, and a metering needle inserted into the housing piston cylinder. A fuel metering mechanism consisting of a main jet that measures the flow rate of the main fuel passage by the annular area of the lever, and a return nup ring that urges the housing piston in a direction that reduces the annular area, is used to measure the flow rate of the intake air in the intake passage. A negative pressure passage is provided outside the intake passage so as not to interfere with the flow, and the housing piston cylinder has a negative pressure passage that opens into the intake passage.
The negative pressure generated in the negative pressure passage causes the housing piston to operate in the direction in which the annular area is expanded, and further the annular area for measuring the flow rate of the main fuel is operated in the direction in which the annular area is expanded. A carburetor characterized by being provided with a stopper for regulating movement of a housing piston. 4. A carburetor in which the metering needle according to claim 1, 2, or 3 is biased to one side within the main jet. 5. A venturi portion in which the negative pressure intake port in the negative pressure passage and the main nozzle in the main fuel passage are respectively formed in the intake passage according to claim 1 or 2 or 8 or 4. vaporizer installed in.