JPH0914114A - Ignition timing control device for engine - Google Patents

Abstract

PURPOSE: To dispense with an exclusive engine temperature state sensing switch, optionally set a switching temperature, and enable switching to multiple stages. CONSTITUTION: An ignition timing control device for an engine has an autochoke device for varying density of air-fuel mixture while controlling current carrying to a heater member 16 whose resistance is varied based on temperatures. Such a control device has a choke voltage sensing means which senses voltage of the heater member 16, and an ignition timing control means 34b which selects one of plurality of ignition timing control maps based on the sensed choke voltage, and controls an ignition timing based on the selected ignition timing control map.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine ignition timing control device for controlling ignition timing based on different ignition timing control maps before and after warming up, for example.

[0002]

2. Description of the Related Art Conventionally, as an ignition timing control device used in a motorcycle or the like, for example, the temperature condition of an engine is detected, and when the engine temperature is less than a predetermined value, the ignition timing is
There is one that is obtained from the pre-warm ignition timing control map, and is obtained from the post-warm ignition timing control map when the predetermined value is exceeded.

[0003]

However, the above-mentioned conventional ignition timing control device requires a dedicated engine temperature detecting switch for detecting whether the engine temperature is lower than or equal to a predetermined value, which causes a problem of high cost. Further, in the case of this method, the operating temperature of the switch is switched in two steps, and a plurality of switches having different operating temperatures are required in order to switch to multiple steps.

The present invention has been made in view of the above-mentioned conventional problems, does not require a dedicated engine temperature state detection switch, and can set the switching temperature to an arbitrary temperature. It is an object of the present invention to provide an ignition timing control device for an engine that can be switched to multiple stages.

[0005]

According to the present invention, there is provided an ignition timing control device for an engine equipped with an auto choke device for changing the concentration of air-fuel mixture by controlling energization of a heater member whose resistance changes with temperature. In the choke voltage detecting means for detecting the voltage of the heater member, and selecting any one of a plurality of ignition timing control maps based on the detected choke voltage, and based on the selected ignition timing control map. And ignition timing control means for controlling the ignition timing.

[0006]

According to the ignition timing control device of the present invention, when the engine is started, the heater member is energized, and the heat generated by the heater member causes the thermowax to expand in volume, so that the concentration of the air-fuel mixture increases with the progress of warming. become thinner. In this case, the electric resistance of the heater member increases with the progress of warming up.

The voltage across the heater member is detected by the choke voltage detection means, and the ignition timing control means
An ignition timing control map corresponding to the detected choke voltage is selected, and the ignition timing is controlled based on the selected map. For example, the pre-warm ignition timing control map and the post-warm ignition timing control map are switched at the choke voltage at the end of the warm-up.

As described above, according to the present invention, the choke voltage of the auto choke device is detected, and the ignition timing control map is switched based on the detected voltage. Therefore, a dedicated engine temperature state detection switch can be eliminated.

Further, since the choke voltage changes according to the progress of the engine warming-up state, the switching voltage can be set arbitrarily, and the ignition timing can be switched among three or more stages. Is.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2 are views for explaining an engine ignition timing control device according to an embodiment of the present invention.
Is a circuit configuration diagram thereof, and FIG. 2 is a sectional view of the auto choke device.

In FIG. 2, reference numeral 6 denotes a starting carburetor which constitutes a main part of the auto choke device, which is located on the venturi portion of the main mixture passage 5a of the main carburetor (not shown).
A starting mixture passage 7 for bypassing between downstream parts is provided, a starting plunger 8 is arranged in a venturi portion of the passage 7 so as to be vertically movable, and a nozzle 7a is opened and closed by a jet needle 8a of the plunger 8. Has been done. A starter well 10 communicating with the float chamber 9 is connected below the plunger 8.

Above the plunger 8, a drive unit 11 is provided.
Is arranged. In the inner case 12b arranged in the outer case 12a of the drive unit 11, a retainer 13 is arranged to be vertically movable and biased upward by a spring 13b. A lower end portion 13a of the retainer 13 is inserted into the plunger 8, and a buffer spring 14 is arranged between the retainer 13 and the jet needle 8a.

A piston supporting portion 15a of a wax case 15 for accommodating a thermowax 15c is inserted inside the retainer 13, and a piston 15b protruding downward from the supporting portion 15a abuts the bottom surface of the retainer 13. Touching. A PTC heater (heater member) 16 whose electric resistance increases as the temperature rises is arranged on the upper surface of the wax case 15. The power supply lead wire 16b of the electrode plates 16a arranged above and below the PTC heater 16 is led out to the outside through the space between the outer case and the inner case 12a, 12b.

In FIG. 1, the PTC heater 16 and the battery 31 are provided with a fuse 32, a main switch 33a,
They are connected via the engine stop switch 33b and the control unit 34. The control unit 34 includes a first transistor 34a for turning on and off the power supply to the PTC heater 16 and a base of the transistor 34a when the engine speed signal a from the engine speed detection sensor 39 is a predetermined value (for example, 800 rpm) or more. It has a CPU 34b for raising the voltage to high. Here, the CPU 34b is configured to set the base voltage to low, for example, every 10 seconds for 5 msec even if the engine speed is equal to or higher than a predetermined value.

A unit resistor 35 is arranged in parallel with the first transistor 34a. The CPU 34
b, the PTC due to the voltage division ratio with the unit resistor 35 while the first transistor 34a is off.
The voltage of the heater 16 is input.

Numeral 36 is an ignition coil for supplying a high voltage to the ignition plug 37, and numeral 38 is a second transistor for turning on / off the power supply to the ignition coil 36.

The CPU 34b also functions as ignition timing control means for controlling the ignition timing by controlling the base voltage of the second transistor 38. That is, the above C
In the PU 34b, the voltage of the PTC heater 16 is a predetermined value,
For example, if it is less than 5 V, the optimum ignition timing according to the engine speed and the throttle opening is obtained from the built-in pre-warm ignition timing control map, and the second transistor 38 is controlled so that the optimal ignition timing is realized. To do. Further, in the case of 5 v or more, the optimum ignition timing according to the engine speed and the throttle opening is obtained from the built-in post-warm ignition timing control map, and the second transistor 38 of the second transistor 38 is configured to realize the optimal ignition timing. Control the base voltage. It should be noted that the ignition timings of the above-mentioned control maps are set so that the ignition timing before warming up (when cold) is retarded after after warming up (when warm).

Next, the function and effect of the apparatus of this embodiment will be described.
In the cold state, the thermo wax 15c is contracted,
The plunger 8 is located at the rising end, and the nozzle 7a to the mixture passage 7 for starting is open as shown in FIG. When the engine is started by turning on the main switch 33a and turning to the starter position in this state, the concentration of the air-fuel mixture supplied to the engine by the fuel from the starting air-fuel mixture passage 7 becomes high and the engine is easily cooled. Start for a while.

When the engine is started, the engine speed becomes 800 rpm or more.
The base voltage of the transistor 34a is set to high, which turns on the transistor 34a so that the battery power source is PTC.
It is supplied to the heater 16. Then, the thermo wax 15c gradually expands in volume due to the heat generated by the PTC heater 16 and pushes down the plunger 8, and the nozzle 7 of the starting mixture passage 7
A is gradually closed and fully closed when the warm-up operation of the engine is completed. As a result, the amount of fuel supplied to the engine from the starting mixture passage 7 decreases as the warm-up state progresses,
It will match the required mixture concentration.

While the engine is operating,
For example, the first transistor 34a is turned off every 5 seconds for 5 ms, and the voltage across the PTC heater 16 (choke voltage) is input to the CPU 34b during the off period, and the CP
U34b controls the ignition timing according to the choke voltage.
That is, the choke voltage is a predetermined value (5 in this embodiment).
If less than v), the CPU 34b, based on the pre-warm (cold) ignition timing control map suitable for cold operation, the operating state at that time (engine speed, throttle opening)
Second transistor 3 so that the optimum ignition timing according to
Control the voltage to 8. When the choke voltage exceeds 5v, the ignition timing is controlled based on a post-warm (warm) ignition timing control map suitable for operation after warm-up.

As described above, in this embodiment, the choke voltage is detected, and the ignition timing control map to be used is selected based on whether the voltage is less than or equal to the predetermined value. The switch can be eliminated. That is, the choke voltage changes according to the temperature condition of the engine. For example, the choke voltage is 1 to 2v in the cold operating condition where the engine temperature is low, and is 10v or more in the operating condition after the warm-up. Become. Therefore, the choke voltage indicates the temperature condition of the engine, and by detecting the choke voltage, a dedicated engine temperature condition detection sensor or the like becomes unnecessary.

In the above embodiment, the choke voltage is 5
The ignition timing control map is switched in two steps depending on whether it is less than v or not, but the switching choke voltage (switching temperature) can be set arbitrarily and can be set to three or more steps. You may make it switch.

[0023]

As described above, according to the engine ignition timing control device of the present invention, the choke voltage of the auto choke device is detected, and the ignition timing control map is switched based on the detected voltage. Therefore, it is possible to eliminate the need for a dedicated engine temperature state detection switch, and by using the existing auto choke device, it is possible to realize ignition timing switching control while suppressing cost increase.

[0024]

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram of an ignition timing control device for an engine according to an embodiment of the present invention.

FIG. 2 is a sectional view of the auto choke device of the above embodiment.

[Explanation of symbols]

16 PTC heater (heater member) 34b CPU (ignition timing control means) 35, 34b Unit resistance, CPU (choke voltage detection means)

Claims (1)

[Claims] 1. An ignition timing control device for an engine, comprising an auto choke device, wherein an air-fuel mixture concentration is changed by controlling energization of a heater member whose resistance changes depending on temperature. Ignition timing for detecting choke voltage detecting means and any one of a plurality of ignition timing control maps based on the detected choke voltage, and controlling ignition timing based on the selected ignition timing control map An ignition timing control device for an engine, comprising: a control means.