JPH01177443A - carburetor starting device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a carburetor that controls the concentration and amount of a mixture supplied to an engine, and particularly to a carburetor that supplies a rich mixture when starting an engine. The invention relates to a starting device.

[Conventional technology]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A conventional starting device for a two-stroke engine carburetor that is commonly used will be explained with reference to FIG.

1, an intake passage 2 passes through the interior thereof, a float chamber body 3 is disposed on the side of the carburetor body 1, and a float chamber 4 is formed by the lower recess of the carburetor body 1 and the float chamber body 3. Ru. In this float chamber 4, a constant liquid level x-x is formed by a float, a float valve, and a valve seat (not shown), and a constant liquid level upper chamber 4 above this constant liquid level x-x is formed.
An air vent hole (■) that communicates with the atmosphere opens at A.

Further, 5 is a throttle valve that opens and closes the intake passage 2.

Reference numeral 6 denotes a partition such as a diaphragm which is separated from the float chamber 4 and divides the inside into a starting fuel pump chamber 7 and an atmospheric chamber 8. Specifically, the starting fuel pump chamber 7 is divided into the partition 6 and the float chamber. The atmospheric chamber 8 is formed by the recess of the main body 3 and the partition body 6
and cover 9.

Note that J is an air hole that communicates the air chamber 8 with the atmosphere.

The following six passages are opened in this starting fuel pump chamber 7. That is, 10 is a starting fuel inflow path which is provided with a suction side check valve 11 inside and communicates with the lower constant liquid level of the float chamber 4. A suction valve seat 12 is formed, and the suction side check valve 11 is pressed against the suction valve seat 12 by a spring 13.

Reference numeral 14 denotes a starting fuel discharge passage whose one end opens approximately in the center of the starting fuel pump chamber 7 and the other end opens into the intake passage 2 on the engine side (left side in the figure) from the throttle valve 5; A spring 1B is attached to the discharge valve seat 15 and the discharge valve seat 15.
A discharge side check valve 17 that is closed by being pressed is disposed.

Further, a valve seat 18 is formed at the opening end of the starting fuel discharge passage to the starting fuel pump chamber 7 . Further, 18 is an on-off valve section provided integrally with the partition body 6.

This opening/closing valve section 18 is located at the valve seat 1 at the end of the starting fuel discharge passage 14.
The valve seat 18 is opened and closed in accordance with the movement of the partition body 6, thereby controlling the opening and closing of the starting fuel discharge passage 14. Further, an operating rod 20 is integrally disposed on the partitioning body 6, and by moving this operating rod 20, the partitioning body 6 and the on-off valve portion 18 are moved synchronously.

N is the first state (first state) in which the operating rod 20 (including the partition body 6 and the on-off valve part 19) is fully pressed toward the starting fuel pump chamber 17 side.
This is an intermediate position regulating member for holding the device approximately in the middle between the state shown in the figure) and the second state in which it is pulled all the way toward the atmospheric chamber 8 side (pulled all the way to the left in the figure). A groove 2OA is formed in the rod 20, and a ball 21 and a spring 22 are used to apply a pressing force perpendicularly to the operating rod 20 with elastic force in the groove 2OA when the operating rod 20 is operated to an intermediate position.

Further, 23 is contracted in the atmospheric chamber 8 and has one end attached to the cover 9.
It is a spring whose other end is locked to the partition body 6 and presses the one partition body 6 toward the starting fuel pump chamber 7 side.

Incidentally, when operating the intermediate position regulating member N described above, the pressing force exerted by the ball 21 by the spring 22 on the groove 20A of the operating rod 20 in a direction perpendicular to the longitudinal axis direction Y-Y of the operating rod 20 is This is greater than the pressing force of the spring 23 in the longitudinal axis direction Y-Y of the operating rod 20 when the operating rod 20 is in the intermediate position, and thereby the operating rod 20 can be held at the intermediate position.

Regarding starting the engine in a state where the ambient temperature is low, before starting the engine, first press the operating lever 20.
is pulled all the way to the left in the figure against the spring force of the spring 23. By this operation, the partition body 6 and the on-off valve section 19 also move to the left in synchronization with the operating rod 20, and the on-off valve The portion 19 opens the valve seat 18 and increases the volume of the starting fuel pump chamber 7.

According to this, the suction side check valve 11 opens the suction valve seat 12, and the discharge side check valve 17 closes the discharge valve seat 15.

Therefore, by such an operation, the fuel stored in the float chamber 4 is sucked into the starting fuel pump chamber 7.

Next, the leftward exchange force on the operating rod 20 is released, and according to this, the operating rod 20 is automatically moved toward the starting fuel pump chamber 7 (to the right) in the figure by the spring force of the spring 23. It moves, and the operating rod 20 is in the groove 2.
0A is stopped in a state where it is engaged with the pawl 21 as the intermediate position regulating member N.

Stopping the operating rod 20 at the intermediate position appropriately strengthens the pressing force of the spring 22 of the pawl 21 acting in a direction perpendicular to the pushing force of the spring 23 in the longitudinal axis direction Y-Y of the operating rod 20. This can be achieved by

When the operating rod 20 is moved to the intermediate position, the starting fuel pump chamber 7 is compressed and the chamber volume is reduced, so that the discharge side check valve 17 opens the discharge valve seat 15 and the starting fuel discharge passage 14 is opened. The starting fuel is injected and supplied into the intake passage 2, thereby preparing the engine for the first and complete explosion, and the process of pulling the operating rod 20 to the left all at once and returning it to the intermediate position. After going through the return process to release the attractive force on the rod, cranking operation for starting the engine begins.

Then, since the fuel in the starting fuel pump chamber 7 has already been injected into the intake pipe from the starting fuel discharge passage 14,
A sufficiently rich air-fuel mixture can be supplied to the engine, ensuring the initial and complete explosion of the engine.

When the engine enters a warm-up operation state after a complete explosion, the operating rod 20 is held at an intermediate position and the valve seat 18 is held open by the opening/closing valve portion 18. The negative pressure acts on the discharge side check valve 17 from the starting fuel discharge passage 14, and the discharge side check valve 17 resists the spring force of the spring 16.
is opened from the discharge valve seat 15, and the fuel in the starting fuel pump chamber 7 is supplied to the intake passage 2 from the starting fuel discharge passage 14 to satisfy warm-up operation.

Next, when the warm-up of one engine is completed, the operating rod 20 is returned from the intermediate position to the original position shown in FIG. According to this, since the on-off valve section 18 closes the valve seat 18,
Fuel does not flow out from the starting fuel pump chamber 7 to the starting fuel discharge passage 14.

[Problem that the invention seeks to solve]

According to such a conventional starting device, the driver senses that the engine ambient temperature is low and, before starting, pulls the operating lever all at once toward the atmospheric chamber and then releases the gravitational force of the operating lever to turn the operating lever. The starting fuel pump is held at an intermediate position and the fuel in the starting fuel pump chamber is injected into the intake airway, but this operation is often carried out within the engine ambient temperature range of -20°C to +20°C.

According to this, for example, the same amount of starting fuel will be injected whether the temperature is -20°C or +20°C, so it takes time to experiment to set the injection amount, which can improve development efficiency. do not have.

[Means for solving problems]

In view of the above drawbacks, the carburetor starting device according to the present invention has the following features:
It is an object of the present invention to provide a device with good starting performance, which allows easy setting work for improving starting performance, and can supply optimal starting fuel for initial explosion, complete explosion, and warm-up operation of the engine, and achieves the above-mentioned purpose. For this purpose, an atmospheric leak passage is opened from the starting fuel pump chamber, one end of which opens into a chamber above a constant liquid level in the float chamber, and the effective passage area of the atmospheric passage is adjusted according to the rise in engine atmospheric temperature. A thermally-responsive valve is installed to increase the

[Effect]

In the process of returning the partition to an intermediate position from the state in which the partition was pulled all the way toward the atmospheric chamber.

The fuel injected from the starting fuel pump chamber to the intake tract leaks into the float chamber from the atmospheric leak passage as the engine ambient temperature rises, so a large amount of fuel can be injected into the intake tract at low temperatures, increasing the temperature. The injection amount could be reduced accordingly.

〔Example〕

The starting device for a carburetor according to the present invention will be explained below with reference to FIGS. 2, 3, and 4.

Components having the same structure as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Reference numeral 30 denotes an atmospheric leak passage, one end of which opens into the constant liquid level chamber 4A of the float chamber 4, and the other end of which opens into the starting fuel pump chamber 7. S is a thermally responsive valve disposed in the atmospheric leak passage 30 and has the following configuration. That is,
31 is located in the atmospheric leak passage 30 and is located above a constant liquid level chamber 4A.
A leak valve seat is located opposite to the side, and a tapered control valve 32 is disposed on the leak valve seat while being pressed by a spring 33.

Reference numeral 34 denotes an expansion/contraction body in which a thermal expansion/contraction member such as paraffin is sealed inside the cylinder, and an operating rod 3 at the end of the expansion/contraction body
4A is arranged opposite to the control valve 32. This I1
In the first contraction body 34, when the engine ambient temperature is low, the thermal expansion and contraction member contracts and moves the operating rod 34A to the left in the figure. As the temperature of the surrounding atmosphere rises, the thermal expansion/contraction member expands and moves the operating rod 34A to the right in the figure.

Note that 35 is a control jet arranged within the atmospheric leak passage 30.

Next, its effect will be explained.

First, the case where the ambient temperature of one engine and the engine temperature are high will be explained. Since the temperature is high, there is no need to supply a rich air-fuel mixture to the engine.

The starting device is therefore kept inactive. In this state, the starting fuel pump chamber 7 is moved by the spring 23 into the partition body 6.
The opening/closing valve part 19, which is integrally provided with the partition body 6, closes and holds the valve seat 1B that opens into the starting fuel pump chamber 7 of the starting fuel discharge passage 14, so that the starting fuel is In this state, the operating rod 34A of the expansion/contraction body 34 moves with strong force to the right, and the control valve 32 moves to the right against the spring force of the spring 33. Although the leak valve seat 31 is held open, this does not pose any problem.

Next, regarding starting the engine in a state where the ambient temperature is low (e.g. -20°C), prior to starting the engine,
First, the operating rod 20 is pulled all the way to the left in the figure against the spring force of the spring 23. At this time, the thermal expansion/contraction member in the expansion/contraction body 34 senses the low temperature state and contracts, so the operating rod 20 34A has moved to the left in the figure. According to this, the control valve 32 is pressed against the leak valve seat 31 by the spring force of the spring 33, so that the atmospheric leak passage 30 is maintained in a fully closed state (not communicating with the atmosphere). This situation is shown in FIG.

By this operation, the partition body 6 and the on-off valve part 19 are also moved to the operating rod 2.
0 and moves to the left in synchronization with the opening/closing valve section 19.
opens the valve seat 18 and increases the volume of the starting fuel pump chamber 7.

According to this, the suction side check valve 11 opens the suction valve seat 12, and the discharge side check valve 17 closes the discharge valve seat 15.

Therefore, by such an operation, the fuel stored in the float chamber 4 is transferred into the starting fuel pump chamber 7.
The increased chamber volume is inhaled.

Next, the leftward exchange force on the operating rod 20 is released, and according to this, the operating rod 20 is automatically moved toward the starting fuel pump chamber 7 (to the right) in the figure by the spring force of the spring 23. The operating rod 20 is movable, and the operating rod 20 stops when the groove 20A is engaged with the pawl 21 serving as the intermediate position regulating member N.

(This state is shown in FIG. 4.) The reason why the operating rod 20 stops at the intermediate position is that the spring 23 acts perpendicularly to the pushing force of the operating rod 20 in the longitudinal axis direction Y-Y. This can be achieved by appropriately increasing the pressing force of the spring 22 of 21.

When the operating rod 20 is moved to the intermediate position, the atmospheric leak passage 30 is closed, and the startup fuel pump chamber 7 is compressed and its volume is reduced.
7 opens the discharge valve seat 15 and injects and supplies starting fuel from the starting fuel discharge passage 14 into the intake passage z, thereby starting the engine.
In preparation for a complete explosion, the process of pulling the operating rod 20 all at once to the left, the operating rod 2 for returning to the intermediate position.
After going through the return process of releasing the gravitational force toward zero, a cranking operation for starting the engine begins. Then, since the fuel in the starting fuel pump chamber 7 has already been injected into the intake pipe from the starting fuel discharge passage 14, a sufficiently rich mixture is supplied to the engine to ensure the initial and complete explosion of the S engine. can be obtained.

When the engine enters a warm-up state after a complete explosion, the operating rod 20 is held at an intermediate position and the valve seat 18 is held open by the on-off valve part 19, so that the engine The negative pressure acts on the discharge side check valve 17 from the starting fuel discharge passage 14, and the discharge side check valve 17 resists the spring force of the spring 16.
is opened from the discharge valve seat 15, and the fuel in the starting fuel pump chamber 7 is supplied to the intake passage 2 from the starting fuel discharge passage 14 to satisfy warm-up operation.

Although the warm-up time varies depending on the performance of the engine and the ambient temperature, the opening/closing valve section 18 holds the valve seat 18 open at the intermediate position due to the intermediate position regulating member N of the operating rod 20, so the starting fuel pump chamber 7, suction negative pressure acts from the starting fuel discharge passage 14, so that the suction side check valve 11 closes to the suction valve seat 1.
Since the fuel in the float chamber 4 can be sequentially supplied by opening the float chamber 2, the same problem does not occur.

Furthermore, according to the starting device according to the invention.

During warm-up operation of the engine, the ambient temperature of the engine gradually rises, and as this temperature rises, the thermal expansion/contraction body inside the expansion/contraction body 34 expands, causing the operating rod 34A to gradually move to the right. According to this, the control valve 32
gradually opens the leak valve seat 31, and this leak valve seat 31
Atmospheric air is allowed to flow into the starting fuel pump chamber 7 through the starting fuel pump chamber 7. As a result, the negative pressure inside the starting fuel pump chamber 7 is weakened, and the amount of fuel sucked into the starting fuel pump chamber 7 from the starting fuel inflow path 10 can be reduced. The fuel supplied from the discharge passage 14 into the intake passage 2 can be diluted.

Therefore, it was possible to significantly improve the warm *M transfer performance.

Then, when the warm-up of one engine is completed, the operating rod 20 is returned from the intermediate opening state shown in FIG. 4 to the original position shown in FIG. 2. According to this, since the opening/closing valve portion 18 closes the valve seat 18, the starting fuel discharge passage 14 is discharged from the starting fuel pump chamber 7.
At this time, the atmospheric leak passage 30 is opened and atmospheric air is introduced into the starting fuel pump chamber 7, but this does not pose a similar problem.

Next, when the engine ambient temperature rises from the low temperature state (-20°C), for example, when starting at a low temperature in the θ°C state, the expansion/contraction body 34 expands and the operating rod 34A is moved to the right, the control valve 32 opens the leak valve seat 31, and the starting fuel pump chamber 7 is kept in communication with the atmosphere. In this state, when the operating rod 20 is pulled all the way to the left, the volume of the starting fuel pump chamber 7 increases and the fuel in the float chamber 4 is sucked into the starting fuel pump chamber 7, but the starting fuel pump Since the chamber 7 is in communication with the atmosphere, the suction force is reduced and reduced fuel is sucked into the starting fuel pump chamber 7.

Next, when the attractive force of the operating rod 20 is released, the operating rod 20 returns to approximately the intermediate position by the spring force of the spring 23 in the same manner as described above, and the starting fuel pump chamber 7 is pressurized by the partition body 6.
A portion of the fuel discharged from the starting fuel pump chamber 7 is returned into the float chamber 4 via the atmospheric leak passage 30.

Therefore, the amount of fuel injected into the intake passage 2 via the starting fuel discharge passage 14 can be reduced, and an appropriate starting fuel can be supplied commensurate with the rise in the IN valve atmosphere temperature, resulting in a significant improvement in starting performance. It is.

The setting of the amount of starting fuel that is optimal for the engine ambient temperature and the amount of air supplied into the starting fuel pump chamber during warm-up are determined by the lift characteristics of the operating lever 34A of the expansion and contraction body 34 with respect to temperature changes, and the leak valve. The seat diameter 31, the taper angle of the valve portion of the control valve 32, the spring characteristics 1 of the spring 33, etc. may be optimally determined through experiments.

Further, the opening of the atmospheric leak passage 30 to the starting fuel pump chamber 30 is not limited to the starting fuel pump chamber 30 but also to the intake valve seat 12.
The starting fuel inflow path 10 closer to the starting fuel pump chamber 30. Alternatively, the starting fuel discharge passage 14 on the starting fuel pump chamber 30 side of the discharge valve seat 15 may be used.

〔Effect of the invention〕

As described above, according to the carburetor starting device of the present invention, the starting fuel injected into the intake duct can be reduced as the engine ambient temperature rises, so the engine is always kept with the optimum starting air-fuel mixture. can be started,
The starting performance can be greatly improved, and the starting experiment can be set up in an extremely short time due to the addition of the rIJ adjustment device.

Furthermore, during engine warm-up, the warm-up air-fuel mixture can be automatically diluted as the engine speed increases, making it possible to significantly improve the warm-up characteristics. °

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of the main parts of a conventional carburetor starting device;
Fig. 2 is a vertical sectional view showing the starting fuel discharge passage of the carburetor starting device according to the present invention in a closed state, and Fig. 3 shows a state in which the operating lever in Fig. 2 is moved toward the atmospheric chamber side more quickly. 4 is a longitudinal sectional view showing a state in which the operating rod has been returned to an intermediate position from the state shown in FIG. 3. 1. Carburizer main body 4. Float chamber 6.
,,, compartment body 7 ,,, starting fuel pump chamber 8
,,,,Atmospheric chamber 10. , Start fuel inlet passage 14, Start fuel discharge passage 18, Valve seat 19. ,,, on-off valve section 20
,,,,Operation rod N,,,,Intermediate position regulating member 2
3. Spring 30. , , Atmospheric leak passage 31 , , Leak valve seat 32. ,,control valve 33,
,,,Suh! J nk 34. ．． ．． ．． [1 body 34A,,
,,operation lever

Claims (1)

[Claims] The interior is divided into a starting fuel pump chamber and an atmospheric chamber by a partition, and a suction side check valve is placed inside the starting fuel pump chamber to allow starting fuel to flow in, which is connected to a constant level below the liquid level in the float chamber. road and
A starting fuel discharge passage in which a discharge side check valve is disposed is opened, and the partition body, which is further pressed toward the starting fuel pump chamber by a spring, has an on-off valve portion that can control opening and closing of the starting fuel discharge passage. and an operating rod capable of applying a pump operating force to the partition body, and a first state in which the starting fuel discharge passage is blocked by the opening/closing valve portion of the partition body;
An intermediate position regulating member N is provided that can hold the partition at a position approximately halfway between the second state in which the partition is pulled toward the atmospheric chamber, and when the attractive force on the operating rod is released from the second state, the partition is held by the spring force of the spring. In a starting device for a carburetor that automatically returns to a substantially intermediate position and discharges fuel in a starting fuel pump chamber through a starting fuel discharge passage, one end of the starting fuel pump chamber is connected to a chamber above a constant liquid level in a float chamber. A starting device for a carburetor comprising a thermally responsive valve that opens an air leak passage and increases an effective passage area of the air leak passage in response to a rise in engine ambient temperature.