JPH01187361A - Starting fuel feeder for internal combustion engine used in portable working machine - Google Patents

Abstract

PURPOSE:To weaken the torque of a motor with a rise in ambient temperature as well as to improve the extent of startability by installing some temperature switches, of which an appropriate one is switched on and gives its accompanying resistance, in a drive circuit of the motor feeding a carburetor with starting fuel. CONSTITUTION:A key switch 43 is constituted of a switch 44 driving an ignition circuit 49 of an internal combustion engine and a switch 45 interlocking with the former. A fixed contact of the switch 45 is connected to a (+) terminal of a battery 41, while the moving contact is connected each to a pump switch 52, each fixed contact of two temperature switches 8, 8a, and one side of terminals of a self-starting motor 46. When ambient temperature in the internal combustion engine is 10 deg.C, by way of example, the temperature switch 8 on one side is opened, while the temperature switch 8a on the other is closed, and a current out of the battery 4 is energized to a motor 36 by way of a resistor 7 and the temperature switch 8a. With this constitution, torque in this motor 36 is weakened to some extent and thereby discharge pressure in a primer pump 37 is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a starting fuel supply vAl for an internal combustion engine for a portable working machine.

[Prior Art] Portable working machines such as chainsaws and brush cutters that require small size and high output are generally equipped with a two-stroke internal combustion engine equipped with a diaphragm-type carburetor that can respond to any changes in the machine's attitude. There is. When starting the engine, the primer pump pumps 1# into the carburetor in order to draw a rich mixture corresponding to the ambient temperature! For example, Japanese Patent Application Laid-Open No. 62-350
47), it is not possible to adjust the starting fuel layer in response to temperature conditions, so a certain degree of skill is required for cold starting the engine.

In recent years, starter motors have been installed in this type of internal combustion engine, making starting operations easier, but depending on temperature conditions, starting fuel 1. What moderates III is not yet known.

[Problem to be Solved by the Invention 1] If the engine is cold, more starting fuel is supplied; on the other hand, if the engine is warm, the engine can be started with less or no starting fuel. Continuously controlling the starting fuel layer according to temperature conditions is possible by using a temperature sensor such as a thermistor, but what about the circuit configuration? ! It becomes complicated and causes an increase in cost.

The object of the invention is to provide a simple temperature switch (fitiffl).
An object of the present invention is to provide a starting fuel supply device for an internal combustion engine for a portable working machine, which can adjust the starting fuel layer in stages according to temperature conditions by using a switch (switch).

[Means for Solving the Problems] In order to achieve the above object, the configuration of the present invention is such that the temperature around the engine is adjusted to the drive circuit of the motor that injects the starting fuel stored in the fuel reservoir into the intake passage of the carburetor. By inserting and connecting multiple temperature switches that have different open operating points to detect and are combined with resistances of different values, as the ambient temperature increases, the motor's negative resistance increases and the motor's rotational force weakens. This is how it was done.

[Operation] When the primer pump 37 is rotated forward, the metering chamber 1
6 fuel is in the passage 40, check valve 39, passage 83, fuel gauge I
The fuel is sucked into the primer pump 37 through the device 81 and the passage 38, and is roughly filled into the fuel reservoir 32 through the passage 30.

Next, when the primer pump 37 is reversely rotated at the same time as the engine is started, the fuel in the fuel reservoir 32 is sucked into the primer pump 37 through the passage 30, acts on the plunger 87 of the fuel metering device 81 through the passage 38, and Room 92b
The fuel is injected from the fuel nozzle 14 through the passages 83, 31 and the check valve 29 into the intake passage 17 of the carburetor.

A plurality of temperature switches 8.8a inserted and connected to the drive circuit of the motor 36 that drives the primer pump 37 are opened when different predetermined temperatures are reached, for example, the temperature switch 8 reaches 3°C, and the temperature switch 8a reaches 15°C. Therefore, when the ambient temperature of the internal combustion engine 27 is, for example, 0°C, the temperature switch 8,
8a are both closed and the temperature switch 8 has no resistance.
The current flowing through causes the motor 36 to rotate strongly, and the primer pump 37 quickly and strongly injects the starting fuel in the metering space 92b of the fuel metering device 81 into the intake passage 17 from the fuel nozzle 14 via the plunger 87.

On the other hand, when the ambient temperature of the internal combustion engine is, for example, io'c, the temperature switch 8 is closed and the temperature switch 8a is closed.
Since the flow flows to the motor 36 through
The flow of the starting fuel injected from b to the fuel nozzle 14 is weak and the flow rate is small (so that starting fuel corresponding to the ambient temperature is supplied).

[Embodiments of the Invention] FIG. 1 shows a schematic configuration of a starting fuel supply system for an internal combustion engine according to the present invention. The starting fuel supply device includes a fuel meter 1 device 81, a positive displacement primer pump 37 such as a gear pump or a vane pump, which is rotated forward and backward by a motor 36, and a fuel supply device disposed between the primer pump 37 and the fuel tank 35. The fuel nozzle 14 is provided with a reservoir 32 and a fuel nozzle 14 disposed in the intake passage 17 of the carburetor 2. The motor 36 is controlled by the battery 41 tlJ@fl! When energized through 42, it rotates forward or backward. The reverse rotation of the motor 36 is caused by the fuel nozzle 14
Under conditions that do not require injection of starting fuel from engine 2,
7 is blocked by a 21 degree switch 8 disposed outside.

The vaporizer 2 introduces pulsating pressure by the diaphragm 6 at the top v5
A fuel pump A is provided with a pump chamber 61 divided into a metering chamber 16 and the atmosphere by a diaphragm 11 at the bottom! i! 62 is partitioned into fuel supply mechanism B. During normal operation of the engine, fuel in the fuel tank 35 flows through the pipe 9.
The fuel is sucked into the fuel pump A, and then sent to the metering chamber 16. The fuel in the metering v16 is sucked into the intake passage 17 by the intake negative pressure in the intake passage 17 via a fuel nozzle (not shown).

Before starting the engine, when the primer pump 37 is rotated forward, the fuel in the metering W16 flows through the passage 40, the check valve 39, the passage 83, and the fuel gauge It fi! 81. The fuel is sucked into the primer pump 37 through the passage 38 and roughly filled into the passage 30 and the fuel reservoir 32, and excess fuel is returned to the fuel tank 35 through the check valve 33 and the pipe 34. In this way, when the pressure in the metering chamber 16 becomes negative, the fuel in the fuel tank 35 is supplied to the metering chamber 16 via the pipe 9, the pump v61 of the fuel pump A, and a passage (not shown).

When the primer pump 37 is reversely rotated when the engine is started, the fuel in the fuel reservoir 32 is sucked into the primer pump 37 through the passage 30, and then through the passage 38 to the fuel gauge ffl device 8.
Sent to 1. The starting fuel in the metering chamber 92b flows through the passages 83, 3.
1. From the fuel nozzle 14 to the intake passage 17 via the check valve 29
It is squirted to

As shown in FIG.
When the gears 77 and 79 supported by the gears 77 and 79 are accommodated in a meshed state, and one of the shafts 76 and 78 is rotated forward (in the direction of the arrow) by the motor 36 (FIG. 1), fuel is sucked from the passage 38 and the gears 77 .79 and is discharged into the passageway 30.

FIG. 3 shows a specific configuration of the control device 42. As shown in FIG. A switch 44 that drives the engine's ignition circuit 49, and 3! I! A moving switch 45 is operated as a key switch 43 by a start key. The fixed contact of the switch 45 is the battery 4
1, and the movable contact is the pump switch 52.
, each fixed contact of temperature switch 8゜8a, starter motor 46
are connected to one terminal of each.

The movable contact of the pump switch 52 is connected to one fixed contact of the changeover switch 55, and the movable contact of each temperature switch 8.88 is connected to one fixed contact of the changeover switch 56. The other fixed contacts of the changeover switches 55 and 56 are connected to one terminal of the battery 41. Changeover switch 55.56
A motor 36 is connected between the movable contacts. The other terminal of starter motor 46 is connected to one terminal of battery 41 via switch 57 .

The start switch 54 consisting of the changeover switches 55, 56 and the switch 57 are interlocked with each other, are normally in the state shown in the figure, and are switched only during the driving period of the starter motor 46.

Key switch 43 before starting the engine (before the engine is rotated)
When the pump switch 52 is closed, the battery 41
An energizing circuit is generated from the switch 45, the pump switch 52, the changeover switch 55, the motor 36, the changeover switch 56, and the battery 41, the motor 36 is rotated in the forward direction, and the primer pump 37 pumps the fuel in the metering chamber 16 as described above. While the fuel reservoir 32 is filled, the fuel tank 35
of fuel is replenished into the metering chamber 16.

Next, when the star 1 switch 54 is switched, an energizing circuit is created that connects the battery 41 to the switch 45, starter motor 46, switch 57, and battery 41, and the starter motor 46 is driven. Also, when the ambient temperature around the engine is 1 degree lower, one or both of the temperature switches 8 and 8a are closed, so the battery 41, switch 45, temperature switch 8 or 8a, changeover switch 56, motor 36, changeover switch 55, An energizing circuit is generated to the battery 41, and the motor 36
is rotated in the opposite direction. Fuel reservoir 32 by primer pump 37
of fuel is sent to the fuel metering device 81, and the fuel metering device 81
The starting fuel flows from the fuel nozzle 14 to the intake passage 1 of the carburetor 2.
7, a rich air-fuel mixture is supplied to the engine, and the engine is started smoothly. When the start switch 54 is returned to the illustrated state, the motor 36 and starting motor 46 are stopped.

In the illustrated embodiment, two temperature switches 8.88 are connected in parallel to each other in the drive circuit of the motor 36. The temperature switch 8 closes the circuit when the temperature is below a low predetermined temperature t1 (for example, 3°C), and opens the circuit when it exceeds 3°C. Temperature switch 8
is not specifically coupled to an external resistor. On the other hand, the temperature switch 8a is set to a lower predetermined temperature t2 (15°C for V/4).
The circuit is closed when the temperature is below, and the circuit is opened when the temperature exceeds 15°C. A resistor 7 is coupled in series to the temperature switch 8a. Therefore, when the ambient temperature of the internal combustion engine is below t1, the temperature switch 8
8a are both closed, but at this time, the motor 36 is driven by the current flowing through the temperature switch 8, the rotational force is strong, and the primer pump 37 causes the fuel to flow rapidly from the fuel metering unit 5utsi to the fuel nozzle 14. Fuel nozzle 14
It is strongly ejected from.

As shown in FIG. 6, when the ambient temperature of the engine is below 11, the temperature switch 8 is closed, so the amount of fuel supplied from the primer pump 37 to the fuel nozzle LF14 is Q2, but the ambient temperature of the engine is tl. If the value is less than t2, the resistor 7 will be inserted into the drive circuit of the motor 36.
The rotational force of the motor 36 becomes weaker, the rotation of the primer pump 37 also becomes weaker, and the movement of the plunger 87 of the fuel metering device 81 becomes slower, so the starting fuel is not completely discharged from the fuel nozzle 14, and the starting fuel amount becomes Ql. This provides a starting fuel amount commensurate with the ambient temperature. When the ambient temperature of the engine exceeds t2, both temperature switches 8, 8a are opened and the motor 36 is not driven, so no starting fuel is sent to the fuel nozzle 14.

FIG. 4 shows how the carburetor 2, which is integrally equipped with a fuel gauge device 81, a primer pump 37, a fuel reservoir 32, and a fuel nozzle 14, is attached to the engine 27. Engine 27 has cylinder 65
A diaphragm type carburetor 2 and an air cleaner (not shown) are attached to the side wall of the engine via a suction pipe 51 made of a heat insulating member. A pipe 9 from the fuel tank 35 is connected to the inlet side of the fuel pump A of the carburetor 2.

The carburetor 2 has an intake passage 17 including a venturi in the main body 3,
It communicates with an intake boat 66 provided in the cylinder 65. A known throttle valve 20 is rotatably supported within the intake passage 17 by a valve shaft 19 .

The cover 4 is coupled to the upper wall of the main body 3 with the diaphragm 6 in between, while the cover 1 is coupled to the lower wall with the diaphragm 11 in between.
5 are combined. The pulsating pressure introduction space 5 is connected to the crank chamber 71 of the engine 27 via a pipe 72. The pump chamber 61 is connected to the pipe 9 via the check valve 48 and to the metering chamber 16 via the check valve 47, the passage 60, and the inlet valve 10.

An atmosphere 62 between the tire flam 11 and the cover 15 that partitions the metering chamber 16 is opened to the atmosphere through a passage 62a. A needle-type inlet valve 10 is disposed at the end of the passage 60 and is opened and closed by a lever 13 supported by a shaft 12 on the wall of the metering chamber 16 . That is, lever 1
One end of the inlet valve 3 is biased and engaged with the end of the inlet valve 10 by the force of a spring.

The other end of the lever 13 abuts against a protrusion connected to the approximate center of the diaphragm 11. Metering 716 is check valve 2
6. Connected to the high speed fuel injection port 24 via the high speed fuel metering needle valve 25. Further, the metering chamber 16 is connected to a low-speed fuel injection port 21 via a check valve 23 and a low-speed fuel metering needle valve 22 .

A housing 50 that accommodates the motor 36 and supports the shaft of the primer pump 37 is coupled to the lower side of the cover 15 . The primer pump 37 is housed inside a casing that is integrated with the cover 15.

One of the suction ports (at the time of forward rotation) of the primer pump 37 is connected to a passage 38, a fuel metering device 81, a passage 83, a check valve 39,
It is connected to the metering chamber 16 via a passage 40, and to the fuel nozzle 14 via passages 83 and 3L check valve 29. The other port (discharge port during forward rotation) of the primer pump 37 is connected to the fuel reservoir 32 via a passage 30. The fuel reservoir 32 is connected to a fuel tank 35 via a check valve 33 and a pipe 34 connected to its lower end. The fuel nozzle 14 is arranged approximately at the center of the inlet side of the intake passage 17, and the nozzle is located at the entrance side of the intake passage 17.
Directed to the downstream side of 7.

The fuel reservoir 32 provided between the primer pump 37 and the fuel tank 35 is preferably constructed from a pipe made of rubber or vinyl. When the primer pump 37 rotates in the reverse direction and the fuel in the fuel reservoir 32 is sucked into the primer pump 37, the check valve 33 closes and prevents the fuel from flowing back from the fuel tank 35.

A fuel metering device 81 is coupled to the underside of the cover 15. As shown in Fig. 5 (a), the fuel metering gi@81 is
The plunger 87 is fitted into the cylinder 82 of No. 4 to define a chamber 92a on the upper side and a measuring chamber 92b on the lower side. The chamber 92a communicates with the primer pump 37 via the passage 38, and the metering chamber 92b communicates with the passage 83.

The plunger 87 is fitted with a seal ring 88 that provides a tight seal between the plunger 87 and the cylinder 82, so that the lower end 85 of the conical shape can abut against a seal member 93 fitted into the cylinder 82. A check valve 95 is provided at the upper end of the plunger 87.

A valve seat 90 having a jet hole 91 is fitted into the open end of the cylindrical valve chamber, and a movable valve body 89 made of a disc made of rubber or the like is housed inside the valve chamber. The valve chamber communicates with the metering chamber 92b through an axial passage 86, a radial passage, and a lower semi-small diameter portion of the plunger 87. When the valve body 89 is pushed down to the end of the passage 86, it changes the space between the v92a and the metering seedling 92b, and when it is pushed up, it hits a plurality of protrusions provided around the jet hole 91 of the seat plate 90, and the valve body 89 connects the metering chamber 92a and the metering chamber 92a. The chamber 92b is communicated.

Next, the operation of the starting fuel supply device for an internal combustion engine for a portable working machine according to the present invention will be explained. When starting the engine 27, the switches 44 and 45 in FIG. 3 are closed, and the pump switch 52 is closed.
When closed, the motor 36 rotates the libraima bomb 37 in the forward direction. The fuel in the metering v16 shown in FIG.
b/\ sucked in, and further the passage 86 of the plunger 87,
It is sucked into the primer pump 37 through the check valve 95, jet hole 91, v92a, and passage 38. Fuel is filled into the fuel reservoir 32 from the primer pump 37 through the passage 3o shown in FIG. Excess fuel pushes open the check valve 33 and drains the pipe 34.
The fuel is returned to the fuel tank 35 through the. At this time, Jietsu I~
The plunger 87 is sucked up by the fluid resistance of the hole 91 and the suction force of the primer pump 37, resulting in the state shown in FIG. 5(b).

Next, when the pump switch 52 in FIG. 3 is opened and the start switch 54 is switched, the primer pump 37 is reversely rotated, and the fuel in the fuel reservoir 32 in FIG. 4 is sucked into the primer pump 37 through the passage 30. Fuel is sent from the primer pump 37 through the passage 38 to the chamber 92a in FIG. 5(b). The check valve 95 is closed by the fuel pressure at 92a, and the plunger 87 is pushed down and abuts against the seal member 93. At this time, the fuel in the metering chamber 92b flows through the passages 83, 31, . The fuel is ejected from the fuel nozzle 14 to the intake passage 17 via the check valve 29 . At the same time, the starter motor 46 smoothly starts the engine 27.

When the ambient temperature of the internal combustion engine is very low, the temperature switches 8 and 8a are both closed, and the motor 36 is rotated strongly by pressing the temperature switch 8, which has a small resistance.

Therefore, by the primer pump 37, the fuel fit 1
Since the fuel pressure sent to the outlet 92a of the device 81 is high, the plunger 87 quickly sends a predetermined amount of starting fuel from the metering chamber 92b to the fuel nozzle 14 at high pressure, creating a rich mixture in the intake passage 17 necessary for cold starting. Qi is generated.

On the other hand, when the ambient temperature of the engine is relatively low, the temperature switch 8 is closed and only the temperature switch 8a is closed.
At this time, the resistor 7 is inserted into the energizing circuit of the motor 36, and the rotation of the motor 36 becomes weaker, the rotation of the primer pump 37 becomes weaker, and the operation of the plunger 87 of the fuel supply device 81 becomes slower. The starting fuel for the seedlings 92b is not completely ejected from the fuel nozzle 14, but a reduced amount of starting fuel corresponding to the surrounding m degree is sent to the intake passage 17.

The embodiment shown in FIG. 3 adjusts the amount of starting fuel in two stages depending on the temperature conditions. For example, the embodiment shown in FIG. By connecting temperature switch No. 3 in parallel with temperature switches 8 and 8a, it is possible to more appropriately adjust the amount of starting fuel in stages according to the ambient tM degree.

In the embodiment shown in FIG. 7, temperature switches 8 and 8a are connected in series, and in this case, a resistor 7 is connected in parallel with the temperature switch 8, which has a low opening point. Therefore, when the surrounding mi of the engine is low, power is supplied from the battery 41 to the motor 36 via the ffl [switch 88.8,
6 is rotated strongly, but if the ambient temperature is high, the temperature switch 8 will open, so the temperature switch 8 will be removed from the battery 41.
a. Electricity is passed through the resistor 7 to the motor 36, and the rotational force of the motor 36 is weakened, producing the same effect as the embodiment shown in FIG.

[Effects of Fe Light] As described above, the present invention provides the drive circuit of the motor that injects the starting fuel stored in the fuel reservoir into the intake passage of the carburetor, which has different opening operating points for detecting the ambient temperature between the lines. By inserting and connecting multiple temperature switches combined with resistances of different values, the motor's load resistance increases and the motor's rotational force becomes weaker as the ambient temperature rises, so temperature switches with different opening operating points are installed. With this combination, the rotational force of the primer pump motor changes, and the amount of starting fuel corresponding to the ambient temperature of the engine is controlled in stages, thereby improving the startability of the engine. Temperature switches are less expensive than thermistors and the like, operate reliably, are stable against vibrations and heat, and have a simple circuit configuration, making it possible to obtain an inexpensive and highly reliable starting fuel supply system.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a starting fuel supply system for an internal combustion engine for a portable working machine according to the present invention, Fig. 2 is a plan sectional view showing an example of a primer pump, and Fig. 3 is a diagram of a motor driving the primer pump. Fig. 4 is a side cross-sectional view showing the specific configuration of the starting fuel supply system, Fig. 15 (a) and (bH) are side cross-sectional views showing the states before and after the fuel gauge Ill operates. FIG. 6 is a miniature diagram showing the relationship between the ambient temperature of the engine and the amount of starting fuel, and FIG. 7 is a circuit diagram showing a partially modified embodiment of the circuit diagram of FIG. 3.

Claims (1)

[Claims] Multiple temperature switches with different opening operating points and connected resistances of different values to detect the ambient temperature of the engine are inserted and connected to the drive circuit of the motor that injects the starting fuel stored in the fuel reservoir into the intake passage of the carburetor. A starting fuel supply device for an internal combustion engine for a portable working machine, characterized in that as the ambient temperature increases, the load resistance of the motor increases and the rotational force of the motor decreases.