JPH11324798A - Starting fuel supply system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an energization circuit for a heat-operated actuator so that a starting valve is closed at appropriate speed and timing after a warm-up. SOLUTION: A starting valve 10 adapted to be closed at high temperature by a heat-operated actuator A is interposed in a starting fuel passage that connects the fuel chamber of a carburetor and a downstream portion of an intake valve in regard to a throttle valve. To an energization circuit for heating the heat-operated actuator A, a PTC thermistor 53 set near to the actuator A and an NTC thermistor set near to an internal-combustion engine are connected in series.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a starting fuel supply system for an internal combustion engine having improved characteristics of a starting valve of a bi-starter.

[0002]

2. Description of the Related Art A thermally responsive actuator for driving a start valve of a bi-starter is disclosed in Japanese Patent No.
Utilizing the thermal expansion of wax as disclosed in Japanese Patent Application Laid-Open No. 9-209,834, a start valve that is open during a cold start of an engine is closed after warm-up. However, in the conventional start-up fuel supply device, when the start-up valve closes after warm-up, the air-fuel ratio cannot be correctly adjusted, and the engine may malfunction.

[0003]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to improve an energizing circuit of a thermally responsive actuator so that a start valve closes at an appropriate speed and at an appropriate time after warm-up. An engine starting fuel supply device is provided.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the configuration of the present invention is to provide a heat-generating device in a starting fuel passage connecting a fuel chamber of a carburetor and a portion of an intake passage downstream of a throttle valve. In a starting fuel supply device for an internal combustion engine having a start valve that closes at a high temperature by a driven actuator, a PTC disposed close to the thermally driven actuator and a PTC disposed close to the internal combustion engine are provided in an energizing circuit for heating the thermally driven actuator. N
And TC connected in series.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a starting fuel supply device (bi-starter) is controlled by controlling the current of an energizing circuit for heating a thermally responsive actuator in accordance with, for example, the temperature of an engine wall, lubricating oil, cooling water and the like. To improve the operating characteristics of the start valve. That is, PTC as a heating element and NT as a temperature sensor
C is connected in series to the energizing circuit, and the closing operation speed of the starting valve is changed stepwise to perform appropriate control of the air-fuel ratio.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, in a starting fuel supply device (bi-starter), a thermally responsive actuator A is formed at the upper end of a cylindrical case body 8 having cylindrical portions 8a to 8d coaxially from the top. The thermal expansion / contraction body 4 filled with wax having a high thermal expansion coefficient is fitted and supported via a seal member. A heat-insulating cup-shaped cover 2 covering the periphery of the thermal expansion / contraction body 4 is fitted over the upper end of the case body 8. For details, see the thermal expansion and contraction body 4
Is fitted to the cylindrical portion 2a of the cover 2 with a PTC (thermistor) 53 interposed therebetween. The heat-expandable body 4 is formed by inserting a piston 7 into a cylinder 5 projecting downward. When the heat-expandable body 4 is heated by an electric current flowing through the PTC 3, the internal wax expands and the piston 7 is removed from the cylinder 5. Protrude downward. The cylinder 5 is attached to the cylindrical portion 8a of the case body 8.
Is slidably fitted, and the lower end of the piston 7 abuts the holder 6. The lower end of the holding body 6 is coupled with a start valve 10 slidably fitted to the cylindrical portion 8b of the case body 8 by an adhesive or the like.

The base flange of the needle valve 10 c is pressed against the bottom of the cylindrical portion 10 a in the upper half of the starting valve 10 by the force of the spring 9. The lower end of the needle valve 10c is the lower end face 10 of the holder 6.
From b, it is inserted into the valve hole of the valve seat 14 fitted and fixed to the steps of the cylindrical portion 8b and the cylindrical portion 8c of the case body 8. An air inlet 12 is provided on one side and a fuel supply port 13 is provided on the other side so as to cross an intermediate portion of the case body 8, that is, the cylindrical portion 8b. The fuel supply port 13 is connected to a portion of the intake passage of the carburetor downstream of the throttle valve through a passage (not shown).

The upper end of the fuel supply pipe 16 is fitted and supported on the cylindrical portion 8c of the case body 8. The upper end of the cylindrical portion 8d having a larger diameter than the cylindrical portion 8c is opened to the outside via the air hole 17. A fuel inlet 20 having a fixed jet 19 is provided at the lower end of the cylindrical portion 8d. The fuel inlet 20 communicates with the fuel chamber of the carburetor through a passage (not shown), and the fuel is accumulated in the cylindrical portion 8d to a height indicated by a line 41. For the convenience of mounting the fuel supply pipe 16, the lower half of the cylindrical portion 8 d is formed by connecting a cup-shaped case main body 18 to the case main body 8.

According to the present invention, the current for heating the thermal expansion and contraction body 4 of the thermally responsive actuator A is controlled in accordance with the temperature change of the engine, and the operating speed of the starting valve 10 driven by the thermally responsive actuator A is controlled. As shown in FIG. 2, a start switch 51, a heating wire 52, a thermistor PTC 53 and an NTC 54 are connected in series to a power battery 50 in order to optimize the valve closing timing. is there.

The PTC 53 is disposed close to the thermal expansion and contraction body 4 of the thermally responsive actuator A, and is used as a heat source of the actuator as shown by a line 53a in FIG. NTC
Numeral 54 is disposed close to the engine so that the temperature of the engine wall, lubricating oil, cooling water, etc. can be detected.
As shown by 4a, it has a characteristic that the resistance decreases with increasing temperature. Therefore, when the PTC 53 and the NTC 54 are connected in series to an energizing circuit for heating the thermal expansion and contraction body 4, when the NTC is cold, the current flowing through the PTC is small, and the PTC generates heat slowly. The starting valve also closes loosely. Conversely, when the NTC is warm, the current flowing through the PTC is large and the PTC generates heat quickly, so that the start valve closes quickly. Time t until start valve 10 is completely closed
Is longer as the temperature of the thermal expansion / contraction body 4 is lower, and shorter as the temperature of the engine is higher. When the start valve 10 is completely closed, the start switch 51 automatically opens.

When the engine is started, when the start switch 51 is closed, the PTC 53 generates heat and the thermal expansion and contraction body 4 is heated. The thermal expansion and contraction body 4 is in a contracted state at normal temperature, and the lower end face 10 b of the start valve 10 has moved above the air intake port 12 and the fuel supply port 13 before the start of the engine. At this time, the air inlet 12 communicates with the fuel supply port 13, the needle valve 10c rises together with the starting valve 10, and the valve hole of the valve seat 14 and the needle valve 10c
, That is, the fuel passage is open. Simultaneously with the cranking of the engine, the intake negative pressure of the intake passage of the carburetor acts on the fuel supply port 13, and the fuel in the cylindrical portion 8 d is mixed with the air from the air hole 17 while the fuel supply pipe 16, the cylindrical portion 8 c,
It flows through the valve hole of the valve seat 14 to the fuel supply port 13, where it flows to the intake passage of the carburetor and the engine while mixing with air from the air intake 12. By the time the engine is started and the warm-up operation is started, the thermal expansion and contraction body 4 expands,
0 is depressed to close the space between the air inlet 12 and the fuel supply port 13.

FIG. 4 shows a conventional circuit in which only the PTC 53 is connected to an energizing circuit for heating the thermal expansion and contraction body 4.
As shown by b and 53c, the start valve closes at the same speed irrespective of a change in the engine temperature or the outside air temperature when the engine is started, and it cannot be said that the fuel is always controlled appropriately. That is, the current decreases as the temperature of the thermal expansion / contraction body 4 increases, and the starting valve 10 closes, so that the air-fuel ratio of the air-fuel mixture supplied to the engine also changes, resulting in malfunction of the engine. This tendency is significant when the ambient temperature is relatively high (eg, about 8 ° C.). On the other hand, in the present invention, since the PTC 53 and the NTC 54 are connected in series to an energizing circuit for heating the thermal expansion and contraction body 4, as shown by a line 55b in FIG. Since the thermal expansion and contraction body 4 is heated at a speed corresponding to the temperature, the time from the start of the start operation of the engine to the closing of the start valve 10 is adjusted according to the start conditions of the engine. Can be controlled.

[0013]

As described above, the present invention is provided with a start valve which is closed at a high temperature by a thermally responsive actuator in a start fuel passage connecting the fuel chamber of the carburetor and a portion of the intake passage downstream of the throttle valve. In the starting fuel supply device for the internal combustion engine,
A PTC disposed close to the thermally responsive actuator and an NTC disposed close to the engine are connected in series to an energizing circuit for heating the thermally responsive actuator, and the thermal expansion and contraction body of the thermally responsive actuator is connected. The engine is heated in accordance with the starting condition of the engine, that is, the temperature of the engine or the outside air temperature, and the closing timing of the starting valve is adjusted according to the operating condition of the engine. Therefore, the fuel is controlled in accordance with the engine start conditions, and smooth engine start and warm-up operation are obtained.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a starting fuel supply device for an internal combustion engine according to the present invention.

FIG. 2 is an electric circuit diagram showing an energizing circuit of the starting fuel supply device.

FIG. 3 is a diagram showing characteristics of the starting fuel supply device.

FIG. 4 is a diagram showing starting characteristics of the present invention and a conventional starting fuel supply device.

[Explanation of symbols]

A: Thermally responsive actuator 2: Cover 4: Thermal expansion / contraction body 5: Cylinder 6: Holder 7: Piston 8: Case body 9: Spring 10: Start valve 10a: Cylindrical section 1
0c: Needle valve 12: Air inlet 13: Fuel supply port 1
4: Valve seat 16: Fuel supply pipe 17: Air hole 18: Case body 19: Diet 20: Fuel inlet 50:
Power battery 51: Start switch 52: Heating wire 5
3: PTC54: NTC

Claims (2)

[Claims] A starting fuel supply device for an internal combustion engine having a starting valve that closes at a high temperature by a thermally responsive actuator in a starting fuel passage connecting a fuel chamber of a carburetor and a portion of an intake passage downstream of a throttle valve. Wherein a PTC disposed close to the thermally responsive actuator and an NTC disposed close to the internal combustion engine are connected in series to an energizing circuit for heating the thermally responsive actuator. Fuel supply device. 2. The starting fuel supply device for an internal combustion engine according to claim 1, wherein a stroke characteristic of the thermally responsive actuator is changed by a PTC and an NTC connected to the energizing circuit.