JP2766657B2 - Engine starting fuel supply device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for supplying fuel to a general-purpose gasoline engine for facilitating starting.

[Conventional technology]

FIGS. 11 (a) and 11 (b) show an example of a conventional fuel supply apparatus using a manual yoke type carburetor for a general-purpose engine. When the fuel supply system of this system is used, the air-fuel ratio during normal operation is such that the fuel vaporization rate during cold weather is poor and the air-fuel ratio (A / F)
It is too thin to start.

Therefore, it is necessary to increase the amount of fuel at the time of starting, and as a means therefor, generally, a chiyoke valve 20 'is provided in front of the venturi portion 22' to restrict the intake air and generate a pressure difference between the chiyoke valve 20 'and the bench lily portion. By applying a large negative pressure to 22 ′ and increasing the pressure difference between the pressure in the float chamber 14 where the atmospheric pressure acts through an equalizing hole communicating with the atmospheric pressure (not shown), a larger amount of fuel than in the normal operation can be obtained. The fuel is supplied from the main nozzle 15 to increase the air-fuel ratio and supply fuel during startup and warm-up operation. There are a manual yoke type and an automatic chiyoke type as the chi-yoke type. Hereinafter, the starting and warm-up operation characteristics of both using this type will be described with reference to FIG.

The startability is the same if the amount of the yoke and the specification of the carburetor 16 are the same, and the characteristic is obtained by cranking the engine (not shown) as described above.
A negative pressure is generated at 22 ', and the fuel in the float chamber 14 is sucked up through the main nozzle 15. However, due to the viscosity of the fuel and the passage resistance of the main jet 28, the start of the fuel from the main nozzle 15 with respect to the intake air is delayed. . Therefore, the change in the air-fuel ratio with respect to the number of cycles at the start is as shown in FIG. 7A. In the first cycle, the fuel is very thin, and the cranking cycle is repeated so that the air-fuel ratio which can be started is obtained.
Start at the point.

Next, regarding the warm-up property, the manual multi-yoke type is warmed up in the chi-yoke state, so as the engine temperature rises, the vaporization rate of the fuel rises, the air-fuel ratio becomes too rich, and stable warming up cannot be obtained . Therefore, the operator needs to adjust the opening of the chi-yoke valve 20 'so that the air-fuel ratio matches the temperature condition of the engine.

The auto chi-yoke type is one of the means for improving the warm-up property of the manual multi-yoke described above. The chi-yoke valve opening is automatically changed according to the engine temperature, and the change in the air-fuel ratio after the start is indicated by a two-dot chain line. Characteristics and maintain an appropriate air-fuel ratio during warm-up. In any case, the number of cranking cycles until the start of the warm-up operation is extremely large, far from the starting performance as shown in FIG. 7 (c).

[Problems to be solved by the invention]

 The above-mentioned prior art has the following problems.

(1) When starting with the chi-yoke system, the start of the fuel from the main nozzle with respect to the intake air is delayed, and the fuel adheres to the inner wall surface of the intake passage. Therefore, a considerable amount of time is required before the air-fuel ratio in the cylinder can be started. The ranking cycle number is required, and the starting performance is poor.

(2) In the manual multi-yoke system, even when the warm-up operation is started, the chi-yoke valve remains fully closed, so that the fuel vaporization rate increases as the engine temperature rises and the air-fuel ratio in the cylinder becomes remarkable. It becomes dark, unstable rotation, engine stall, etc. Therefore, it is necessary for the operator to adjust the opening degree of the chi-yoke valve so as to obtain an appropriate air-fuel ratio while observing the operating condition of the engine, and the operation requires considerable skill.

(3) The auto chi-yoke system is one of the means for improving the warm-up operation characteristics of the manual multi-yoke system.
As the engine temperature rises, the chi-yoke valve opens automatically to optimize the air-fuel ratio during warm-up operation.
Since a temperature sensor, an actuator, and the like are required, the structure becomes complicated and the cost is increased. In addition, as described in the section of the prior art, the starting performance is far from the ideal starting performance as shown in FIG.

Therefore, according to the present invention, the cranking cycle number from the start of starting to the flammable range due to the air-fuel ratio characteristics at the time of starting shown in (a) or (b) of FIG. 7 is low (a in FIG. 7).
And the air-fuel ratio after reaching the combustible range, that is, the air-fuel ratio at the time of idling operation (or warm-up operation) after the initial explosion (b in FIG. 7). It is an object of the present invention to provide a fuel supply device which does not require a skilled operation and does not require a complicated auto chi-yoke mechanism and has excellent startability.

[Means for solving the problem]

The present invention relates to an engine provided with a carburetor in which a fuel supply amount to a float chamber is controlled via a valve interlocked with a float, wherein a first communication passage communicating with an intake passage of an engine including the carburetor and the carburetor are provided. A second communication passage communicating with the container float chamber and communicating with the fuel tank via the fuel supply passage and the gas release passage, and allowing a predetermined amount of the measured fuel to pass through the first and second communication passages. This problem has been solved by providing an engine starting fuel supply device having a fuel delivery mechanism for supplying the intake passage and the carburetor float chamber.

In the above-described engine starting fuel supply device, the fuel delivery mechanism may be configured to separately measure and deliver a predetermined amount of fuel to the first communication passage and the second communication passage.
The cylinder mechanism and the second piston / cylinder mechanism can be used as a double piston / cylinder mechanism. Further, the fuel delivery mechanism may include a branch passage for distributing and supplying the combined amount of fuel to the intake passage and the carburetor float chamber to the first communication passage and the second communication passage. it can.

According to the present invention, there is provided an engine provided with a carburetor in which a fuel supply amount to a float chamber is controlled via a valve interlocked with a float, the engine having a communication passage communicating with the float chamber of the carburetor, a fuel tank and a fuel supply A fuel delivery mechanism that communicates through a passage and a gas vent passage and supplies a measured predetermined amount of fuel to the carburetor float chamber through the communication passage, wherein the fuel delivery mechanism is partially a carburetor In order to increase the amount of fuel, the starting fuel supply device for an engine having a piston-cylinder mechanism having a predetermined volume for metering out a predetermined amount of fuel whose other part overflows from the carburetor main nozzle into the intake passage is also used. Solved the problem.

(Operation)

1. In order to improve low temperature startability, fuel is supplied into the cylinder without increasing the air-fuel ratio at the start and without delaying the air flow due to the intake action of the piston, and the rich air-fuel ratio required for the start Is supplied into the intake passage for the purpose of securing the fuel from the first cranking.

This is the temperature at which the starting environment temperature is below the freezing point, for example, -5 ° C.
It is effective in ensuring the startability under the following temperature conditions.

2. At a simple carburetor model shown in FIG. 8, P _0: absolute body pressure atmosphere or Benchiyuri upstream absolute body pressure ^{(Kgf / m 2 abs) P} 1: Benchiyuri throat of the absolute body pressure ( Main nozzle tip pressure (Kgf / m ² abs) P ₂ : Main jet inlet pressure, P ' ₂ : Main jet outlet pressure (Kgf / m ² abs) h: Head of main nozzle tip with respect to float chamber oil level (m) H: head for Meinjietsuto inlet of the float chamber oil level (m) a: cross sectional area (m ²⁾ C: flow coefficient g: gravitational acceleration (m / s ²⁾ r: specific weight (Kgf / m ³⁾ G: weight flow rate (Kgf / s) Subscript a: air f: fuel Since P ₀ −P ₁ = constant, the oil level in the float chamber is increased and the h is reduced, so that the A / F is small, that is, the air-fuel ratio is increased, and the oil level in the float chamber is increased. And h becomes large, that is, when going down to the oil level controlled by the float, Ga / G
f changes in the large direction, the air-fuel ratio is controlled to be thin, and starts from the rich side and changes to the air-fuel ratio range of the normal operation range on the thin side, so that the warm-up operation that is idle operation is performed. continue.

By the time the increased amount of fuel is consumed in the float chamber, the cylinder temperature of the engine increases, and the vaporization rate of the fuel in the cylinder increases, so that the operation is continued with normal carburetor performance.

3. By performing fuel supply by combining the above 1 and 2, the engine is started with the minimum number of cranking cycles and the idling operation (warm-up operation) under the environmental temperature condition below the freezing point, and then reaches the normal operation. In addition, if the temperature range is a lower limit temperature of the general use environment temperature of the working machine, for example, a temperature range of 5 ° C. or more, only the fuel is supplied to the float chamber in an increased amount, and the engine is started with the number of cranking cycles in the range using the recoil starter. After that, idling elapses, and it becomes possible to operate at an arbitrary load on the control oil level of a normal vaporizer.

4. The fuel supply inside this suction passage and to the float chamber is as follows: (1) A two-stage piston and cylinder piston that are automatically connected to the source position by spring force When in the original position (initial position), fuel is sucked into each stroke volume, and when it is displaced by a single external force, it is sent out from each delivery port to the communication path via the check valve, and the suction passage Alternatively, it is sent to the float chamber.

Each delivery amount is determined by matching the displacement volume of the two-stage piston to the delivery amount.

(2) The fuel delivery means may be a single-stage piston displacement type having a volume delivery amount for delivering the total amount of fuel supplied to the float chamber and the suction passage.

At this time, it is possible to distribute and supply the desired amount by dividing the flow path after the check valve of one outlet into the communication with each opening of the float chamber and the suction passage, and by narrowing each communication path. it can.

(3) Since the pressure equalizing hole communicating with the atmosphere of the float chamber or the upstream side of the bench lily has a certain head with respect to the tip of the main nozzle, the fuel supplied to the float chamber overflows the main nozzle and is sucked. It may be a single-stage piston-cylinder type delivery means capable of supplying a fixed amount into the passage and delivering the total amount.

(4) In the configuration of (3) above, if the fuel supply means is such that the fuel supplied to the float chamber does not necessarily overflow, the working machine is used at an environmental temperature of 5 ° C. or more. Is provided when it is obvious.

In the above-described fuel supply process, the operation of the chi-yoke valve is completely unnecessary, that is, the chi-yoke valve is unnecessary or even if it is left fully open, the starting operation can be easily performed.

That is, in the low-pressure carburetor: a) The air-fuel ratio at the time of starting changes as shown in Fig. 9 by supplying the fuel in advance into the suction pipe, and the cranking is performed several times or less if the appropriate amount is charged. Start with the number of cycles.

b) If the amount of fuel is increased and supplied to the float chamber,
As shown in FIG. 10, when the first explosion is given, the cylinder temperature rises, the amount of fuel vaporized increases, and the air-fuel ratio shifts from (a) to (b) in FIG. 10 to maintain idling.

c) By providing the opportunity of the first explosion in the above item b) by the means of a), that is, by a + b, an ideal air-fuel ratio characteristic at the time of starting shown in FIG. A gasoline engine with high performance will be obtained.

It is clear from the above-mentioned theory that if the lower limit of the operating environment temperature of the engine is raised, or the lower limit of the gasoline lead pressure is raised, or the application is limited, only the above b) is practical.

〔Example〕

Hereinafter, a first embodiment of the present invention having two systems for internal start-up and warm-up will be specifically described with reference to FIGS. 1 (a) and 1 (b).

In the figure, 1 is a fuel tank, 2 is a hook, 3 is a fuel pump, 4 is a fuel pipe, 5 is a fuel supply pipe, 6 and 7 are measuring sections,
8 is a communication passage, 9 is a vent pipe, 10 is a piston, 11, 12
Is a check valve, 13 is a suction passage, 14 is a float chamber, 15 is a main nozzle, 16 is a carburetor, 17 is a spring, 18 is a float,
19 is a stopper, 20 and 21 are holes, 22 and 23 are communication paths, 24 and 25 are throttles, 26 is a float chamber oil level, and 28 is a main jet.

In a general-purpose engine with a carburetor (not shown), as shown in FIG. 1 (a), a fuel reservoir (or measuring unit) 6 capable of storing a certain amount of starting fuel at a first level, A fuel reservoir (or measuring unit) 7 capable of storing a certain amount of warm-up fuel is provided, and both fuel reservoirs are provided with a plurality of communication passages 8.
To communicate.

The inlet side passage (or fuel supply pipe 5) of both fuel reservoirs (or measuring sections) is opened upward in the first level fuel reservoir 6, and the other end is in the middle of the fuel pipe 4 connecting the fuel tank 1 and the carburetor 16. The fuel vents 9 are opened at the same height as the inlet side passage 5 in the fuel reservoir 6, and the other end is opened at the upper part of the fuel tank 1.

The outlet passage of the fuel reservoir 7 is connected to the check valve 12 and the communication passage 23.
Through the opening 21 in the suction passage 13 after the bench lily portion of the carburetor 16, and the outlet side passage of the fuel reservoir 6 through the communication passage 22 through the check valve 11 in the float chamber 14 of the carburetor 16. The starting fuel supply system is formed by communicating with the opening 20.

The check valves 11a, 12b are pressed upward by return springs 11b, 12b, and normally close the outlet side passages 6 ', 7'. However, the check valve may be a reed valve.

The above-described fuel reservoirs 6 and 7 are provided integrally or separately at the upper part of the carburetor 16 main body.

The starting operation simply pushes the piston 10 all the way.

The piston 10 returns to the standby position (the state shown in FIG. 1A) by the return spring 17. When the piston 10 is pressed, a certain amount of fuel stored in the fuel reservoir 7 is compressed after the piston 10 closes the communication passage 8, and the compression pressure is reduced by a check valve.
When the spring force of the return spring 12b exceeds 12, the check valve 1
1a is pushed downward, the outlet side passage is opened, and the starting fuel is supplied into the suction passage 13 through the communication passage 23.

A certain amount of fuel stored in the fuel reservoir 6 is compressed after the piston 10 closes the fuel supply pipe 5 and the gas vent pipe 9,
When the compression pressure becomes larger than the spring force of the return spring 11b of the check valve 11a, the check valve 11a is pushed downward, the outlet side passage is opened, and fuel is communicated with the opening 20 in the float chamber 14. It is supplied into the float chamber 14 through 22.

FIG. 1 (b) shows that a specific amount of fuel at the first level
A state in which a specific amount of fuel of the second level is supplied to the float chamber 14 is shown. The oil level position 26 in the float chamber 14 is higher than the normal position 26 shown in FIG. The head difference h between the tip 15 'and the oil level 26 is reduced.

The float 18 in this state has hit the stop 19.

As shown in FIG. 7, a change in the air-fuel ratio with respect to the number of cycles indicates that the fuel required for the start is supplied into the intake passage 13 before the start. And start. After starting, float room 14
Since the increased amount of fuel is supplied from the main nozzle 15, the air-fuel ratio in the cylinder has the characteristic shown by the solid line, and stable warm-up properties can be obtained.

Next, a second embodiment will be specifically described with reference to FIGS. 2 (a) and 2 (b).

A fuel reservoir (30) capable of storing first and second levels of fuel required for starting and warming is provided, and a fuel supply pipe (5) of the fuel reservoir (30) is opened above the fuel reservoir (30). The other end is opened in the middle of the fuel pipe 4 connecting the fuel tank 1 and the carburetor 16, and the gas vent pipe 9 for venting the gas in the fuel reservoir 30.
Is opened at the same height as the fuel supply pipe 5 in the fuel reservoir 30,
The other end is opened at the upper part of the fuel tank 1.

The outlet of the fuel reservoir 30 is connected to the carburetor 16 through the check valve 11.
To the opening 20 in the float chamber 14 via the communication path 22 to form a starting fuel supply system. Check valve 11a is return spring 1
The connection path 22 is pressed upward by 1b and normally closed.

The above-described fuel reservoir 30 is provided integrally or separately at an upper portion of the vaporizer 16 main body.

 The starting operation simply pushes the piston 10 all the way.

The piston 10 returns to the standby position (the state shown in FIG. 2A) by the return spring 17.

The fixed amount of fuel stored in the fuel reservoir 30 is compressed after the piston 10 closes the fuel supply pipe 5 and the gas vent pipe 9, and the compression pressure is reduced by the spring force of the return spring 11b of the check valve 11a. When it becomes larger, the check valve 11a is pushed downward, the outlet side passage 22 is opened, and the fuel is supplied into the float chamber 14.

The fuel supplied to the float chamber 14 fills the float chamber 14 and then the starting fuel is supplied from the main nozzle 15 to the vaporizer.
It is supplied to the inside of the suction passage 13 of 16.

In the form of the second embodiment, the starting fuel is supplied to the main nozzle 15.
Since it is necessary to fill the float chamber 14 with fuel in order to supply the fuel into the suction passage 13 of the vaporizer 16 from the
If the amount of fuel that fills the interior 14 is far beyond the amount of fuel required for warming up and there is a problem, the dead volume in the upper part of the float chamber 14 is adjusted.

In the case of this embodiment, a working machine having a temperature range in which the starting operation can be performed only by increasing the amount of fuel to the float chamber can be used without intentionally causing overflow. In addition, the volume of the fuel reservoir 30 may be set in accordance with this.

 Next, a third embodiment is shown in FIGS. 3 (a) and 3 (b).

The metering of the sum of the first and second levels of fuel is performed by the piston 10 of the second embodiment. The connection between the fuel delivery port and the communication path is divided into two paths at the outlet side of the check valve, and is connected to the opening 20 of the float chamber and the opening 21 of the suction path via the communication paths 22 and 23, respectively. Communication and squeeze 2 on each connection
4 and 25 are provided to distribute and supply the fuel delivered from the piston 10. The subsequent operation and effect are the same as those of the first embodiment, but the configuration is simple.

 Next, specific experimental examples will be described.

Q ₁ = Initial fuel quantity in the suction pipe (CC) Q ₂ = Increased fuel quantity in the float (CC) Based on the relationship between Q ₁ and Q ₂ when the quantity is increased, the dimension when the dimension is made dimensionless by the displacement standard (VthCC) Indicates the range of Q ₁ / Vth and Q ₂ / Vth.

FIGS. 4 to 6 show the results of tests performed using a 4-cycle engine with Vth = 192 CC (single cylinder) and continuous rated output = 3.5 Ps / 3600 vpm.

FIG. 4 shows the gasoline lead pressure Pf = 0.45 kgf / cm ² G, 0.9
5 kgf / cm ² ambient temperature (AT) AT = 35 ℃ a soak-out temperature of the engine with respect to G, 20 ° C., and -5 ° C., number of cranking cycles until the initial explosion at the time of changing the Q ₁ Indicates N ₁ (first explosion characteristic). a) Pf = 0.45Kgf / cm ² G, b) Pf = 0.
The case of 95 kgf / cm ² G is shown. The required value of N ₁ and N ₁ veq, N ₁ v
When eq = 10, Q ₁ opt = 0.6 CC (Q ₁ op) through a) and b)
t = the reasonable value of Q ₁₎ and it can be seen.

Since Q ₁ ≠ 0, the lower limit is 0.1 CC, so 0.1∠Q ₁ 1.1 CC. (1) In FIG. 5, Q ₂ is changed as Q ₁ = 0.6 CC, AT = -5 ° C., Pf = 0.95 kgf / cm ² G At this time, the number of cranking cycles until the idling operation is continued, that is, until the complete explosion (that is, the number of complete explosion cycles N _P ) is obtained by measuring the rotation speed of the engine.

From the characteristics of the rotation speed to the number of cranking cycles shown in the figure, when Q ₂ = 0, N _P = ∽ when Q ₂ = 2, N _P = 7, when Q ₂ = 5, N _P = 6, when Q ₂ = 10, N _P = give 14 results of which are shown in FIG. 6 as N _P -Q ₂ properties.

The required value of N _P and N _P Veq = 10 as N _P Veq when Q ₂ =. 1 to
It turns out that it is 8CC. (2) on the other hand, Therefore, it is determined that the ratio of Q ₁ and Q _{2 to} the displacement does not lose generality even if the engine changes.

〔The invention's effect〕

As described above, according to the present invention, the following effects are obtained.

(1) By only pushing the plunger once, the start-up fuel is supplied to the inside of the suction chamber, enabling one-shot start-up, and the warm-up fuel is supplied into the float chamber of the carburetor to ensure stable warm-up. obtain.

(2) It becomes possible to use a short-yoke carburetor, which simplifies the starting operation with one touch.

(3) Stable startability is obtained under any use conditions of the user.

(4) A starting fuel supply device using a carburetor without a chiyoke valve can be obtained.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are cross-sectional views of essential parts during standby and operation in a first embodiment of the present invention, and FIGS. 2 (a) and 2 (b).
FIGS. 3A and 3B are main-portion cross-sectional views of the second embodiment of the present invention during standby and operation, and FIGS. 3A and 3B are main-portion cross-sectional views of the third embodiment of the present invention during standby and operation. FIG. 4 is a diagram of a test result of the initial explosiveness, wherein a) shows a case where the gasoline lead pressure is low and b) shows a case where the gasoline lead pressure is high. FIG. 5 is a diagram showing a test result of the complete explosion, FIG. 6 is a diagram showing an increase in the amount of fuel into the float chamber and a test result of the complete explosion, and FIG. 7 is a start-up diagram according to the embodiment of the present invention. FIG. 8 is a diagram illustrating the calculation of the air-fuel ratio characteristics of the carburetor, and FIG. 9 is a line showing the influence of the injection amount of the suction pipe when there is no fuel supply from the carburetor. Fig. 10, Fig. 10 is a diagram showing the effect of the injection amount of the vaporizer float chamber when there is no suction pipe injection, Fig. 11 is a sectional view of the main part of the conventional apparatus, (a) is a front view, and (b) is It is a side view. 1 ... Fuel tank, 6,7 ... Measurement unit 10 ... Piston, 13 ... Suction passage 14 ... Float chamber, 15 ... Main nozzle 16 ... Vaporizer 22,22 ... Connection path

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02M 1/16

Claims (4)

(57) [Claims] 1. An engine provided with a carburetor in which a fuel supply amount to a float chamber is controlled via a valve interlocked with a float, a first communication passage communicating with an intake passage of an engine including the carburetor and the first communication passage. It has a second communication passage communicating with the carburetor float chamber and communicates with the fuel tank via the fuel supply passage and the gas vent passage, so that a predetermined amount of fuel is metered through the first and second communication passages. An engine starting fuel supply device comprising a fuel delivery mechanism for supplying the intake passage and the carburetor float chamber. 2. The fuel delivery mechanism according to claim 1, further comprising a first piston-cylinder mechanism and a second piston-cylinder mechanism for separately metering and delivering a predetermined amount of fuel to the first communication path and the second communication path. The engine starting fuel supply device according to (1), further comprising a double piston-cylinder mechanism. 3. The fuel delivery mechanism according to claim 1, further comprising a branch passage for distributing and supplying the combined amount of fuel to the intake passage and the carburetor float chamber to the first communication passage and the second communication passage. The fuel supply device for starting an engine according to the item (2). 4. An engine provided with a carburetor in which the amount of fuel supplied to a float chamber is controlled via a valve interlocked with a float, the engine having a communication passage communicating with the float chamber of the carburetor, a fuel tank and a fuel tank. A fuel delivery mechanism that communicates via a supply passage and a gas release passage and supplies a measured predetermined amount of fuel to the vaporizer float chamber via the communication passage, wherein the fuel delivery mechanism is partially vaporized An engine having a predetermined volume piston-cylinder mechanism for metering out a predetermined amount of fuel that is overflowing from the carburetor main nozzle to the intake passage so as to increase the fuel in the vessel. Fuel supply device.