JP2001263165A - Auto choke control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy of an auto choke control without increasing a cost. SOLUTION: When engine speed detected by an engine speed detection sensor 49 is above a set engine speed, energizing time to a PTC type heater 42 to be a heater for auto choke is made to be performed by a pulse control of a transistor 47 by a microcomputer 46, external resistance for regulating voltage to the heater for auto choke conventionally used can be unnecessitated. When the auto choke is applied to an engine of a different characteristics, the application can be easily coped by changing an on-pulse width in the microcomputer 46 according to the characteristics of an applied engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic choke control device and, more particularly, to an automatic choke control device capable of easily changing an energizing time to an auto choke heater.

[0002]

2. Description of the Related Art Some car carburetors are provided with an auto choke so that a good start and a warm-up operation are automatically obtained according to an outside air temperature and a warm-up state of an engine. is there. Some auto chokes have an auto choke heater and are provided integrally with a vaporizer.

In an auto choke provided with an auto choke heater, a part of the voltage generated by a flywheel magnet is applied to the auto choke heater to cause the ceramic plate to generate heat. Further, the thermowax is expanded by the heat of the ceramic plate, the starter plunger is operated, and the supply amount of fuel is adjusted.

As an example of such an automatic choke control device, Japanese Patent Laid-Open Publication No. Hei 8-42398 discloses a method of adjusting the voltage to an automatic choke heater by changing the resistance value of a voltage adjusting resistor which is an external resistor. Like that.

[0005] That is, as shown in FIG. 8, one end of an auto choke heater 1 is connected to a control transistor 3 via a voltage adjusting resistor 2. The heater 1 for auto-choke expands thermowax for performing a closing operation of a starter plunger (not shown) by heat. The voltage adjusting resistor 2 has a predetermined resistance value in order to adjust the voltage to the heater 1 for the automatic choke.

The control transistor 3 includes a three-phase magnet 4
The ignition signal of the ignition coil 4a is input as the engine speed, and a voltage is applied to the auto choke heater 1 when the engine speed is input. An ignition plug 6 is connected to the ignition coil 4a via a capacitor discharge igniter (CDI) 5.

A three-phase magnet 4 is connected to the other end of the auto choke heater 1 via a regulator 7. A battery 9 is provided between the auto-choke heater 1 and the lamp switch 8 for turning on the lamp 8a.
Is provided.

In such a configuration, when the engine speed is input to the control transistor 3 by starting the engine, the voltage is applied to the auto choke heater 1 by the ON operation of the control transistor 3. At this time, since the voltage applied to the auto-choke heater 1 is adjusted by the voltage adjusting resistor 2 so as to decrease, the expansion of the thermowax (not shown) becomes gentle. As a result, since the closing operation of the starter plunger (not shown) is performed gently, an abrupt change in the fuel supply amount is avoided, thereby preventing the occurrence of engine stall.

[0009]

However, in the above-described conventional automatic choke control device, the voltage to the auto choke heater 1 is adjusted by the voltage adjusting resistor 2 as an external resistor. In this case, since the resistance value of the voltage adjustment resistor 2 is constant, it is necessary to set the resistance value in accordance with the characteristics of the engine to be mounted. , The voltage must be adjusted. Therefore, there is a problem that a cost increase is caused by such a measure by replacing the voltage adjusting resistor 2.

If the voltage to the auto-choke heater 1 is simply adjusted by the voltage adjusting resistor 2, the voltage adjusting resistor 2 has a constant resistance value.
Since the auto choke is not controlled according to the engine temperature, the air-fuel mixture becomes temporarily rich and consumes wasteful fuel.On the other hand, the air-fuel mixture becomes thin and takes a long time to warm up. There is also a problem that accuracy of choke control is reduced.

The present invention has been made in view of such a situation, and an object of the present invention is to provide an automatic choke control device capable of improving the accuracy of the automatic choke control without increasing the cost. Things.

[0012]

According to the first aspect of the present invention, there is provided an automatic choke control device for applying heat to a thermowax for driving a sliding throttle valve for opening and closing a fuel passage for starting a carburetor to expand the thermowax. An auto-choke control device comprising an auto-choke heater using a battery as a power source and controlling energization of the auto-choke heater from the battery, wherein the auto-choke is performed when an engine speed is equal to or higher than a set speed. A pulse control means for pulse-controlling the energization time to the heater. Further, the pulse control means may include a transistor for interrupting the current supply from the battery to the heater for auto choke, and a microcomputer for applying a pulse width modulated on-pulse to a base of the transistor. Further, the microcomputer is configured to adjust the width of the on-pulse according to a temperature detected by a temperature detection sensor that detects an engine temperature. When the detected temperature is high, the width of the on-pulse to the base of the transistor is adjusted. And when the detection temperature is low, the width of the on-pulse can be varied so as to narrow the width of the on-pulse to the base of the transistor. In the auto choke control device according to the present invention, the pulse control means does not use an external resistor for adjusting the voltage to the auto choke heater. The energization time is pulse-controlled and the width of the on-pulse is varied according to the detected temperature.

[0013]

Embodiments of the present invention will be described below.

FIG. 1 is an equivalent circuit diagram showing an embodiment of the automatic choke control device of the present invention, FIG. 2 is a diagram for explaining the operation of the automatic choke control device of FIG. 1, and FIG.
4 is a diagram showing an example of a motorcycle engine to which the auto choke control device of FIG. 1 is applied, and FIGS. 4 to 6 are diagrams showing an auto choke provided in the carburetor of FIG.

First, an engine to which the automatic choke control device of FIG. 1 is applied will be described with reference to FIGS.

Cylinder block 1 of the engine shown in FIG.
0, a piston 1 connected to a connecting rod 11
2 are provided. A cylinder head 15 having a combustion chamber formed between the cylinder block 10 and the piston 12 is provided above the cylinder block 10.

The cylinder head 15 has a camshaft 1
An intake valve 18 and an exhaust valve 19 that are opened and closed by the rocker arm 6 and the rocker arm 17 are provided. An intake manifold 20 is connected to the cylinder head 15. The intake manifold 20 is provided with a carburetor 2 for generating an air-fuel mixture sent into the combustion chamber.
1 is provided.

On the other hand, the vaporizer 21 is provided with, for example, an auto choke 22 as shown in FIG. The auto choke 22 shown in FIG. 4 is provided with a starting fuel adjusting device A and a temperature-sensitive driving device B. The starting fuel adjusting device A further includes a starting air passage 28 and a starting air-fuel mixture passage 2.
9 are provided.

As shown in FIG. 5, for example, the starting air passage 28 is provided in the main air supply passage 27 in the throttle valve 26.
The starting air-fuel mixture passage 29 is communicated with the main air supply passage 27 downstream of the throttle valve 26. Further, a sliding throttle valve 31 of the starting fuel adjusting device A is disposed between the starting air supply passage 28 and the starting air-fuel mixture passage 29, and the sliding throttle valve 31 is connected to the float chamber 24.
Has been communicated to.

The specific configuration of the starting fuel adjusting device A and the temperature-sensitive driving device B of the auto choke 22 shown in FIG. 4 is as shown in FIG. That is, the starting fuel adjusting device A is provided on the carburetor main body 23, and the temperature-sensitive driving device B is provided on the upper side of the starting fuel adjusting device A.

In the lower part of the vaporizer main body 23, a float chamber 2 is provided.
A starter well 25 communicating with 4 is provided. Further, in the carburetor main body 23, the above-described starting mixture passage 2 is provided.
9 are provided internally.

A metering needle valve 33 to be inserted into a starting fuel nozzle 32 is attached to the sliding throttle valve 31 of the starting fuel adjusting device A. The sliding throttle valve 31 is a temperature-sensitive drive device B
A spring 35 interposed between the side set collar 34 and the set collar 34 biases the set collar 34 downward.

The set collar 34 has a piston 38 and a case 38 for accommodating a fluid 37 such as rubber or silicone.
Has been charged. The case 38 contains a thermo wax 3
A cap-like body 40 accommodating 9 is attached. Fluid 3
7 and thermowax 39 are separated by a diaphragm 41.

On the upper part of the cap 40, a thermo wax 3
A PTC type heater 42, which is an auto choke heater of the auto choke control device that expands 9 by heat, is in contact with it. The PTC heater 42 has terminals 43 and 44.
The power is supplied via a female coupler 45 connected to the power supply.

That is, as shown in the equivalent circuit of FIG. 1, the automatic choke control device comprises an ECU 48 having a PTC heater 42, a microcomputer 46 and a transistor 47.
, A rotation speed detection sensor 49 and a temperature detection sensor 50
And Here, the microcomputer 46 and the transistor 47 constitute pulse control means.

The rotation speed detection sensor 49 gives a detection signal of ACG or crank pulsar generated when the engine rotates to the ECU 48. The temperature detection sensor 50 detects the engine temperature (the temperature inside the water-cooled jacket) and supplies a detection signal to the ECU 48.

One end of the PTC heater 42 is connected to a power supply line 51 connected to a battery (not shown). The other end of the PTC heater 42 is connected to the collector of the transistor 47. PWM (pulse width modulation) is applied to the base of the transistor 47 by the microcomputer 46.
A controlled on-pulse is applied.

The microcomputer 46 applies an on-pulse 51 a having a PWM (pulse width modulated) width shown in FIG. 2 to the base of the transistor 47 when the engine speed obtained by the speed sensor 49 is equal to or higher than the set speed, for example. To turn on the transistor 47.

That is, such PWM (pulse width modulation) control is operated by a program programmed in advance in accordance with the characteristics of the engine, so that the characteristics of the engine during the warm-up operation are the same regardless of the model. They show the same characteristics.

Next, the operation of the automatic choke control device having such a configuration will be described.

First, when the engine is started, the thermo wax 39 shown in FIG. 6 is in an expanded state corresponding to the ambient temperature, and the amount of protrusion of the piston 36 from the case 38 also corresponds to the ambient temperature. Thus, the operating position of the sliding throttle valve 31 also corresponds to the ambient temperature.

In this state, when a main switch (not shown) is turned on and the engine is started by rotating to a starter position, the starting air passage 2 serving as a starting fuel passage is started.
The concentration of the mixture supplied to the engine through the mixture passage 8 and the starting mixture passage 29 is increased, and the engine is easily started in a cold state.

When the engine is started, its rotational speed is detected by a rotational speed detecting sensor 49. When the rotational speed exceeds a set rotational speed, the microcomputer 46 shown in FIG.
The transistor 47 is driven by WM (pulse width modulation) control. As a result, the transistor 47 is turned on, and the current from the power supply line 51 is supplied to the PTC heater 42.

At this time, due to the heat from the PTC type heater 42, the thermo wax 39 shown in FIG. Close to. Then, at the time when the warm-up operation of the engine is completed, the starting fuel nozzle 32 is fully closed. As a result, the amount of fuel supplied to the engine through the starting air passage 28 and the starting air-fuel mixture passage 29, which is the starting fuel passage, decreases as the warm-up state progresses, and coincides with the required air-fuel mixture concentration.

During the warming-up of the engine, when the engine temperature (the temperature inside the water-cooling jacket) rises, the temperature is detected by the temperature detecting sensor 50. Therefore, even when the engine is stopped during warm-up, the microcomputer 46 maintains the drive of the transistor 47 by the above-described PWM (pulse width modulation) control until the engine temperature becomes equal to or lower than the predetermined value.

If the engine is restarted while the engine temperature is high after the engine is stopped, fuel is not supplied through the starting air passage 28 and the starting air-fuel mixture passage 29, which are the starting fuel passage, and the engine is not supplied to the engine. Is equal to that during normal operation, and coincides with the required mixture concentration.

When the engine temperature drops below a predetermined value after the engine is stopped, the thermowax 39 gradually contracts, and the blocking of the starting fuel nozzle 32 by the metering needle valve 33 is gradually released. Therefore, when the engine is restarted after a considerable amount of time has elapsed after the engine is stopped, the mixture concentration becomes high as in the case of starting the above-described ambient temperature.

As described above, in the present embodiment, when the engine speed detected by the speed detection sensor 49 is equal to or higher than the set speed by the microcomputer 46, power is supplied to the PTC type heater 42, which is an auto choke heater. Since the time is controlled by the pulse control of the transistor 47, it is not necessary to use an external resistor for adjusting the voltage to the heater for the auto choke which has been conventionally used. When such an auto choke is applied to an engine having a different characteristic, it can be easily coped with by changing the on-pulse width in the microcomputer 46 according to the characteristic of the engine to be applied, thereby avoiding an increase in cost. Can be

The automatic choke control by the PWM (pulse width modulation) control of the transistor 47 can reduce the variation in the operation time of the automatic choke as compared with the conventional voltage adjustment using an external resistor. This is because the PWM (pulse width modulation) control of the transistor 47 is smaller than the conventional variation in the resistance of the external resistor.

In this embodiment, a case has been described in which the energization time to the PTC heater 42 is controlled by the pulse control of the transistor 47 when the engine speed is equal to or higher than the set speed. Not only
PWM (pulse width modulation) control of the transistor 47 can also be performed by linking to a detection signal from the temperature detection sensor 50 that detects the engine temperature.

In this case, for example, as shown in FIG. 7, the microcomputer 46 is provided with a map indicating the relationship between the detected temperature and the width of the on-pulse 51a to the base of the transistor 47. When the temperature detected by the temperature detection sensor 50 is high, the width of the on-pulse 51a to the base of the transistor 47 is widened, so that the auto choke control time can be shortened.

When the temperature detected by the temperature detection sensor 50 is low, the width of the on-pulse 51a to the base of the transistor 47 is narrowed, so that the auto-choke control time can be lengthened. This improves the accuracy of the automatic choke control because the mixture does not temporarily become rich and consumes wasteful fuel, and conversely the mixture becomes thin and does not take time to warm up. Can be.

When detecting the temperature of the engine, a method of directly detecting the temperature of the engine body such as a cylinder block or a cylinder head, or a method of detecting the temperature of cooling water in the case of a water-cooled engine is used. Can be. In the transistor 47, the FET
By using the (field effect transistor), the output of the auto choke control device can be increased, and the versatility can be further improved.

[0044]

As described above, according to the automatic choke control device of the present invention, the engine speed is equal to or more than the set speed by the pulse control means without using an external resistor for adjusting the voltage to the heater for the auto choke. In this case, the energizing time to the auto choke heater is pulse-controlled, and the width of the on-pulse is varied according to the detected temperature, so that the accuracy of the auto choke control can be improved without increasing the cost. .

[Brief description of the drawings]

FIG. 1 is an equivalent circuit diagram showing an embodiment of an automatic choke control device according to the present invention.

FIG. 2 is a diagram for explaining an operation of the automatic choke control device of FIG. 1;

FIG. 3 is a diagram showing an example of a motorcycle engine to which the auto choke control device of FIG. 1 is applied.

FIG. 4 is a sectional view showing the auto choke of FIG. 3;

FIG. 5 is a sectional view taken along line aa of the auto choke of FIG. 4;

6 is a sectional view showing a specific configuration of the auto choke of FIG.

FIG. 7 is a diagram showing another embodiment of the automatic choke control device of FIG. 1;

FIG. 8 is an equivalent circuit diagram showing an example of a conventional auto choke control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Auto-choke heater 2 Voltage adjustment resistor 3 Control transistor 4 Three-phase magnet 4a Ignition coil 5 Capacitor discharge igniter (CDI) 6 Ignition plug 7 Regulator 8 Lamp switch 8a Lamp 9 Battery 10 Cylinder block 11 Connecting rod 12 Piston 15 Cylinder head Reference Signs List 16 camshaft 17 rocker arm 18 intake valve 19 exhaust valve 20 intake manifold 21 carburetor 22 auto choke 23 carburetor main body 24 float chamber 25 starter well 26 throttle valve 27 main air supply passage 28 starting air passage 29 starting air-fuel mixture passage 31 Sliding throttle valve 32 Fuel nozzle for starting 33 Metering needle valve 34 Set collar 35 Spring 36 Piston 37 Fluid 38 Case 39 Thermo wax 40 Cap-shaped body 41 Die Diaphragm 42 PTC type heater 43 Terminal 44 Terminal 45 Coupler 46 Microcomputer 47 Transistor 48 ECU 49 Rotation speed detection sensor 50 Temperature detection sensor 51 Power line 51a On pulse A Starting fuel adjustment device B Temperature sensitive drive device

Claims (3)

[Claims] 1. An auto-choke heater having a battery as a power source for heating and expanding a thermo-wax for driving a sliding throttle valve for opening and closing a fuel passage for starting a carburetor, the auto-choke. An auto-choke control device for controlling energization of the heater for the battery from the battery, comprising: pulse control means for pulse-controlling the energization time to the heater for the auto choke when the engine speed is equal to or higher than a set speed. An automatic choke control device. 2. The apparatus according to claim 1, wherein the pulse control unit includes: a transistor for interrupting power supply from the battery to the heater for auto choke; and a microcomputer for applying a pulse width modulated on-pulse to a base of the transistor. The auto choke control device according to claim 1, wherein 3. The microcomputer according to claim 1, wherein the microcomputer adjusts a width of the on-pulse in accordance with a temperature detected by a temperature detection sensor for detecting a temperature of the engine. 3. The width of the on-pulse is varied so that the width of the on-pulse is increased and the width of the on-pulse to the base of the transistor is reduced when the detected temperature is low.
The automatic choke control device according to 1.