JPH01177442A - carburetor starting device - Google Patents

Abstract

PURPOSE:To enable the supply of a starting fuel quantity matching an engine atmosphere temperature by enabling the restriction of a shift stroke toward the side of an atmosphere chamber for a division body such as a diaphragm for increasing or decreasing the volume of a starting fuel pump chamber with an increase in the engine atmosphere temperature. CONSTITUTION:In starting an engine at a low temperature, an operation lever 20 is first fully drawn toward the left side against the force of a spring 23, and a diaphragm 6 is displaced in the same direction. Fuel in a float chamber 4 is thereby drawn into a starting fuel pump chamber 7 via an intake side check valve 11. Then, a tension force for the operation lever 20 is released and this lever 20 is returned to the right side by the help of the force of the spring 23 and the pump chamber 7 is compressed, thereby injecting starting fuel into an intake passage 2 via a delivery side check valve 17 and the like. On the other hand, at an engine start in a condition where the engine atmosphere temperature rises from a low temperature condition, a thermal expansion and contraction body 33 expands and a movable retainer 32 is moved to the right side. Consequently, the displacement of the diaphragm 6 due to the pull operation of the lever 20, or a starting fuel quantity is reduced.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a carburetor that controls the concentration and strength 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 has an intake passage 2 passing through it, a float base body 3 is arranged on the side of the carburetor body 1, and a float chamber 4 is formed by the four lower parts of the carburetor body 1 and the float base body 3. Ru. A constant liquid level xx is formed within the float chamber 4 by a float, a float valve, and a valve seat (not shown).

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

Reference numeral 6 denotes a partitioning body such as a diaphragm that 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 partitioning body 6 and the float basic body. The atmospheric chamber 8 is formed by the concave portion of 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 passages are opened in this starting fuel pump chamber 7. That is, reference numeral 10 is a starting fuel inflow path which is provided with a suction check valve 11 inside and communicates with the lower constant liquid level of the float chamber 4, and the starting fuel inflow path is provided with a suction side check valve 11. 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 whose other end opens into the intake passage 2 on the engine side (left side in the figure) from the throttle valve 5. In the discharge passage, a discharge valve seat 15 and a spring 16 are attached to the discharge valve seat 15.
A discharge control 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 . Moreover, 19 is an on-off valve part provided integrally with the partition body 6, and this on-off valve part 19
is arranged corresponding to the valve seat IB at the end of the starting fuel discharge passage 14, and opens and closes this valve seat 18 in accordance with the movement of the partition body 6,
The opening and closing of the starting fuel discharge passage 14 is thereby controlled. 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 18) 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 bored in the rod 20, and a pawl 21 and a spring 22 apply elastic force to the groove 2OA to apply a pressing force orthogonally to the operation rod 20 when the operation 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 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 pawl 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 part 18 also move to the left in synchronization with the operating rod 2o, 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 pulling force on the operating rod 20 is released. 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 ball 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 23 of the ball 21 acting in a direction perpendicular to the pressing 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 then the process of pulling the operating rod 20 to the left all at once, and the operation to return 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, the fuel in the starting fuel pump chamber 7 becomes the starting fuel discharge path in the intake pipe! Since the injection has already been supplied from 4,
Supply the engine with a sufficiently rich mixture! ! The first explosion of the engine,
You can definitely get a complete blast.

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 1B.
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 the 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 IJt system, the driver senses that the engine ambient temperature is low, and before starting the engine, pulls the operating lever all at once toward the atmosphere chamber, and then releases the attractive force of the operating lever. is held at an intermediate position, and the fuel in the starting fuel pump chamber is injected into the intake airway. 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. Therefore, the movement stroke of the partition toward the atmospheric chamber side is made smaller as the engine atmosphere temperature increases by 1.

[Effect]

If the movement stroke of the partition body toward the atmospheric chamber side is made smaller as the engine atmosphere temperature increases E, the movement stroke of the partition body returning to the intermediate position from the state in which the partition body is fully pulled toward the atmospheric chamber side will increase in temperature. This makes it possible to reduce the amount of starting fuel injected as the engine ambient temperature rises.

〔Example〕

Hereinafter, the carburetor starting device of the present invention will be explained with reference to FIGS. 2, 3, 4, and 5.

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 annular glue retainer disposed on the partition body 6 on the side of the atmospheric chamber 8 and on the outer periphery of the operating rod 20, and 31 is a ring-shaped glue retainer that is bored in the cover 9 and surrounds the operating rod 20 passing through the cover 9. An open end 31A of the storage recess 31 opens into the atmospheric chamber 8. A movable retainer 32 is disposed within the storage recess 31 and is slidably guided and held around the outer periphery of the operating rod 20 and has a flange 32A at the end on the atmospheric chamber 8 side.

The flange 32A of the movable retainer 32 and the storage recess 31
A thermally expandable and contractible body 33 whose length (L) in the longitudinal axis direction Y-Y of the operating rod 20 changes in response to temperature changes is disposed within the storage section 31 between the bottom portion 31A and the bottom portion 31A.

As a specific example, an example in which bimetals are laminated will be shown.

Further, reference numeral 34 denotes a spring compressed within the atmospheric chamber 8, one end of which is placed on the collar portion 32A of the movable retainer 32, and the other end placed on the beam retainer 30.

Next, its effect will be explained.

First, a case where the engine atmosphere temperature 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. This state is shown in FIG. 2, where the partition body 6 is pressed toward the starting fuel pump chamber 7 by the spring 34.
The opening/closing valve part 19 provided integrally with the partition body 6 closes and holds the valve seat 18 of the starting fuel discharge passage 14 that opens into the starting fuel pump chamber 7, so that the starting fuel is not discharged. In this state, the thermal expansion and contraction body 33 is stretched l1ail toward the atmospheric chamber 8 side and moves the movable retainer 32 toward the atmospheric chamber 8 side, so the spring force of the spring 23 increases, and the blockage between the opening/closing valve portion 19 and the valve seat 18 is prevented. You can definitely do it.

Next, regarding starting the engine in a state where the ambient temperature is low (e.g. -20°C), prior to starting the engine,
First, pull the operating rod 20 all the way to the left in the figure against the spring force of the spring 23.
The movable retainer 32 side end face 30A of the movable retainer 32 moves by 1 until it comes into contact with the flange 32A of the movable retainer 32. In this embodiment, the cross 1 moves by 18 mm.

This situation is clearly illustrated in FIG. By this operation, the partition body 6 and the on-off valve section 19 are also moved to the left in synchronization with the operating rod 20, and the on-off valve section 19 opens the valve seat 18 and increases the chamber volume of the starting fuel pump chamber 7. let

According to this, the suction side valve 11 opens the suction valve seat 12, and the discharge side return 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. The operating rod 20 is movable, and the operating rod 20 stops when the groove 2OA is engaged with the pawl 21 as the intermediate position regulating member N.

More specifically, the distance 7 between the groove 2OA and the pole 21 is moved by a distance of 1+ minus 1.If 1 sentence 2 is 6 mm, the operating rod 20 is the difference between 18 mm and 6 mm. In other words, it automatically returns to the 12 mm starting fuel pump chamber 7 side. (This state is shown in FIG. 4.) The fact that the operating rod 20 stops at the intermediate position F acts perpendicularly 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 appropriately increasing the pressing force of the spring 22 of the pawl 21.

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 return valve 17 opens the discharge valve seat 15 and the starting fuel discharge passage 14 is opened. The process of injecting and supplying starting fuel for the 12 mm stroke of the partition body 6 into the intake passage 2, thereby preparing the engine for the first and complete explosion, and then pulling the operating rod 20 to the left all at once. After the return process of releasing the attractive force on the operating rod 20 to return to the intermediate position, 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 can be supplied to the engine, ensuring the initial and complete explosion of the engine. Obtainable.

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 1B.
is opened from the discharge valve seat 15, and the fuel in the starting fuel pump chamber 7 is released into the starting fuel discharge path! 4 to the intake passage 2 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 the suction side reverse ratio valve 11
Since the fuel in the float chamber 4 can be sequentially supplied by opening the float chamber 2, there is no problem.

Next, when the warm-up of the 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 on-off valve section 19 closes the valve seat 18, the starting fuel discharge passage 14 is discharged from the starting fuel pump chamber 7.
No fuel will leak to.

Next, when starting at a low temperature in a state where the engine ambient temperature has risen from the low temperature state (-20°C), for example, 0°C, the thermal expansion and contraction body 33 disposed in the storage recess 31 is As the temperature rises, the movable retainer 32 expands and moves toward the atmospheric chamber 8. This state is shown in FIG.

According to this, sentence 1 at -20°C is reduced to sentence, ', for example! L1' is 12 mm. In this state, when the operating rod 20 is pulled all the way to the left, the operating rod 20 moves 12 mm to the left.

Then, when the attractive force of the operating rod 20 is released, the operating rod 20 compresses the starting fuel pump chamber 7 by (1'-fL2), and in this example, the 6 mm starting fuel pump is (12 mm - 6 mm). The pump moves toward the chamber 7 side, and injects and supplies fuel in the starting fuel pump chamber 7 into the intake passage 2 via the starting fuel discharge passage 14 in an amount commensurate with this stroke.

Thus, when the engine ambient temperature rises, the amount of starting fuel to be injected can be automatically reduced, thereby improving the startability of the engine.

The above shows a specific example, and the thermal expansion and contraction body 3
The specific structure of No. 3, its arrangement, and the setting of No. 11 for temperature rise are optimally selected as desired.

〔Effect of the invention〕

As described above, according to the carburetor starting device of the present invention, the starting fuel injected into the intake passage can be reduced as the engine ambient temperature rises, so that the optimum starting air-fuel mixture can always be maintained. The engine can be started,
The starting performance can be greatly improved, and the experiment for starting can be carried out in an extremely short time due to the increase in the number of adjustment devices.

[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 cross-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 the operating rod in Fig. 2 pulled back to the atmospheric chamber side. Fig. 4 is a longitudinal sectional view showing a state in which the operating lever has been returned to the intermediate position from the state in Fig. 3, and Fig. 5 is a longitudinal sectional view showing a state in which the engine atmosphere temperature has increased compared to the state in Fig. 2. It is a longitudinal cross-sectional view showing a closed state of a fuel discharge passage. 1. Carburetor body 4. ,,, Float chamber 6 ,,
,, compartment body 7. ,,,starting fuel pump chamber 8,
,,,atmospheric chamber 10. ,,,starting fuel inflow path 14
,,,,Starting fuel discharge passage tS,,,,valve seat

Claims (2)

[Claims] (1) 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, which is connected to a constant level below the liquid level in the float chamber. A starting fuel inflow passage and a starting fuel discharge passage in which a discharge side check valve is disposed are opened, and a partition body that is pressed toward the starting fuel pump chamber by a spring is provided with a starting fuel discharge passage that opens and closes. A controllable opening/closing valve part and an operating lever capable of applying a pump operating force to the partition body are integrally provided, and the operating lever includes:
An intermediate position regulating member N is provided which can hold the starting fuel discharge passage in a first state in which the opening/closing valve portion of the partition body is closed and a second state in which the partition body is pulled toward the atmospheric chamber. When the attractive force on the operating rod is released from the second state, the partition body is automatically returned to the approximately intermediate position by the spring force, and the fuel in the starting fuel pump chamber is discharged through the starting fuel discharge passage to start the carburetor. A starting device for a carburetor that reduces the movement stroke of a partition toward an atmospheric chamber as the engine ambient temperature rises. (2) 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, which is connected to a constant liquid level below the float chamber. A starting fuel inflow passage and a starting fuel discharge passage in which a discharge side check valve is disposed are opened, and a partition body that is pressed toward the starting fuel pump chamber by a spring is provided with a starting fuel discharge passage that opens and closes. A controllable opening/closing valve part and an operating lever capable of applying a pump operating force to the partition body are integrally provided, and the operating lever includes:
An intermediate position regulating member N is provided which can hold the starting fuel discharge passage in a first state in which the opening/closing valve portion of the partition body is closed and a second state in which the partition body is pulled toward the atmospheric chamber. When the attractive force on the operating rod is released from the second state, the partition body is automatically returned to the approximately intermediate position by the spring force, and the fuel in the starting fuel pump chamber is discharged through the starting fuel discharge passage to start the carburetor. In the device, a thermal expansion/contraction member is placed within the movement range of the partition or the operating rod toward the atmospheric chamber, and the expansion of the thermal expansion/contraction member as the engine ambient temperature rises causes the atmospheric chamber of the partition or the operating rod to expand. A carburetor starting device with a small side movement stroke.