JP3532306B2 - Engine ignition timing control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine for which the ignition timing is controlled based on different ignition timing control maps, for example, before and after warm-up. The present invention relates to an ignition timing control device. 2. Description of the Related Art Conventionally, as an ignition timing control device used for a motorcycle or the like, for example, an engine temperature state is detected, and when the engine temperature is lower than a predetermined value, the ignition timing is determined.
In some cases, it is determined from a pre-warm-up ignition timing control map, and if the predetermined value is exceeded, it is determined from a post-warm-up ignition timing control map. [0003] However, the conventional ignition timing control device requires a dedicated engine temperature detection switch for detecting whether the engine temperature is less than or equal to a predetermined value, resulting in an increase in cost. There is. In addition, in this method, switching is performed in two stages based on the operating temperature of the switch, and a plurality of switches having different operating temperatures are required to perform switching in multiple stages. The present invention has been made in view of the above-mentioned conventional problems, and 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 in multiple stages. SUMMARY OF THE INVENTION The present invention controls power supply to a PTC heater whose resistance changes with temperature , and
Due to the volume expansion of the thermo wax due to the heat generated by the heater,
The ignition timing control apparatus for an engine having an automatic choke apparatus which vary the mixture concentration gradually lowers the plunger, the automatic choke device, the
While controlling the power supply to the PTC heater,
A transistor that is turned off at predetermined time intervals during the
With unit resistors arranged in parallel with the resistor
The above transistor is off during engine operation.
P based on the partial pressure ratio with the unit resistance during the period
A choke voltage detecting means for detecting a choke voltage which is a voltage between both ends of the TC heater , and selecting one of a plurality of ignition timing control maps based on the detected choke voltage; And ignition timing control means for controlling the ignition timing based on the ignition timing. [0006] According to the ignition timing control device according to the present invention, is energized in PCT heater when the engine is started, the PCT arsenide
Thermo wax to volume expansion by heating the over data, the air-fuel mixture concentration with the progress of warming-up becomes thinner. In this case, the electric resistance of the PCT heater increases as the warm-up progresses. [0007] P based on the partial pressure ratio with the unit resistance
The voltage (choke voltage) across the CT heater is continuously detected, and an ignition timing control map corresponding to the detected choke voltage is selected by the ignition timing control means, and the ignition timing is continued based on the selected map. Is controlled.
For example, the pre-warm-up ignition timing control map and the post-warm-up ignition timing control map are switched at the boundary of the choke voltage at the end of the warm-up. As described above, according to the present invention, the choke voltage of the automatic 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. Since the choke voltage changes in accordance with the progress of the warm-up state of the engine, the switching voltage can be set arbitrarily, and the ignition timing can be switched among three or more stages. It is. Embodiments of the present invention will be described below with reference to the accompanying drawings. FIGS. 1 and 2 are views for explaining an engine ignition timing control apparatus according to an embodiment of the present invention.
Is a circuit configuration diagram, and FIG. 2 is a cross-sectional view of an auto choke device. In FIG. 2, reference numeral 6 denotes a starting carburetor constituting a main part of the automatic choke device, which is disposed above a venturi portion of a main mixture passage 5a of a main carburetor (not shown).
A starting air-fuel mixture passage 7 that bypasses between the downstream portions is provided, and a starting plunger 8 is disposed in the venturi portion of the passage 7 so as to be vertically movable, and the nozzle 7a is opened and closed by a jet needle 8a of the plunger 8. Have been. A starter well 10 communicating with the float chamber 9 is connected below the plunger 8. Above the plunger 8, a driving unit 11
Is arranged. A retainer 13 is disposed in an inner case 12b disposed in an outer case 12a of the drive unit 11 so as to be vertically movable and biased upward by a spring 13b. The lower end 13a of the retainer 13 is inserted into the plunger 8, and a buffer spring 14 is disposed between the plunger 8 and the jet needle 8a. A piston support 15a of a wax case 15 for accommodating a thermo wax 15c is inserted into an upper portion of the retainer 13, and a piston 15b projecting downward from the support 15a is brought into contact with a bottom surface of the retainer 13. In contact. A PTC heater (heater member) 16 whose electric resistance increases with an increase in temperature is arranged on the upper surface of the wax case 15. The power supply lead wires 16b of the electrode plates 16a arranged above and below the PTC heater 16 are led out through the space between the outer and inner cases 12a and 12b. In FIG. 1, the PTC heater 16 and the battery 31 are connected to a fuse 32, a main switch 33a,
It is connected via an engine stop switch 33b and a 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 an engine speed signal a from the engine speed detection sensor 39 is equal to or more than a predetermined value (for example, 800 rpm). A CPU 34b for raising the voltage is provided. Here, even if the engine speed is equal to or higher than a predetermined value, the CPU 34b sets the base voltage to low for 5 msec, for example, every 10 sec. A unit resistor 35 is provided in parallel with the first transistor 34a. CPU 34
b, during the period in which the first transistor 34a is off, the PTC is determined by the voltage dividing ratio with the unit resistor 35.
The voltage of the heater 16 is input. Reference numeral 36 denotes an ignition coil for supplying a high voltage to the ignition plug 37, and reference numeral 38 denotes a second transistor for turning on and 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
The PU 34b sets the voltage of the PTC heater 16 to a predetermined value,
For example, when the ignition timing is less than 5 V, an optimum ignition timing corresponding to the engine speed and the throttle opening is obtained from a built-in ignition timing control map before warm-up, and the second transistor 38 is controlled so that the ignition timing is realized. I do. 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 ignition timing control map after warm-up, and the second transistor 38 is controlled so that the ignition timing is realized. Control the base voltage. The ignition timing of each control map is set so that the timing before warm-up (when cold) is retarded after warm-up (when warm). Next, the operation and effect of this embodiment will be described.
In a cold state, the thermo wax 15c is contracted,
The plunger 8 is located at the rising end, and the nozzle 7a to the starting mixture passage 7 is open as shown in FIG. In this state, when the engine is started by turning on the main switch 33a and rotating to the starter position, the concentration of the mixture supplied to the engine by the fuel from the mixture passage 7 for starting is increased, 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 high, which turns on the transistor 34a, and the battery power
It is supplied to the heater 16. Then, due to the heat generated by the PTC heater 16, the thermowax 15 c gradually expands in volume and pushes down the plunger 8, and the nozzle 7 in the mixture passage 7 for starting
is gradually closed, and fully closed when the warm-up operation of the engine is completed. As a result, the amount of fuel supplied from the starting mixture passage 7 to the engine decreases as the warm-up state progresses,
It will be equal to the required mixture concentration. During the operation of the engine,
For example, the first transistor 34a is turned off every 5 seconds for 5 milliseconds. During the off period, the voltage (choke voltage) across the PTC heater 16 is input to the CPU 34b and the CP 34b is turned off.
U34b performs ignition timing control according to the choke voltage.
That is, the choke voltage is a predetermined value (5 in this embodiment).
If the value is less than v), the CPU 34b determines the current operating state (engine speed, throttle opening) based on the pre-warm (cold) ignition timing control map suitable for cold operation.
The second transistor 3 so that the optimal ignition timing according to
Control the voltage to 8. When the choke voltage exceeds 5 V, the ignition timing is controlled based on the after-warm-up (at warm-up) ignition timing control map suitable for the after-warm-up operation. As described above, in the present 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. Switches can be eliminated. That is, the choke voltage changes in accordance with the temperature state of the engine. For example, the choke voltage is 1 to 2 V in a cold operation state in which the engine temperature is low, whereas it is 10 V or more in an operation state after the completion of warm-up. Become. Therefore, the choke voltage indicates the temperature state of the engine, and the detection of the choke voltage eliminates the need for a dedicated engine temperature state detection sensor or the like. In the above embodiment, the choke voltage is 5
Although the ignition timing control map is switched between two stages depending on whether it is less than or greater than v, the switching choke voltage (switching temperature) can be set arbitrarily, and can be changed over three or more stages. Switching may be performed. [0023] As is evident from the foregoing description, according to the ignition timing control apparatus for an engine according to the present invention, the choke voltage continuously detects the automatic choke device, the ignition based on the detected choke voltage Since the timing control map is switched, a dedicated engine temperature state detection switch can be dispensed with, and there is an effect that ignition timing switching control can be realized while suppressing cost increase by using an existing auto choke device. [0024]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an electric circuit diagram of an engine ignition timing control device according to one embodiment of the present invention. FIG. 2 is a sectional view of the automatic choke device of the embodiment. [Description of Signs] 16 PTC heater (heater member) 34b CPU (ignition timing control means) 35, 34b Unit resistance, CPU (choke voltage detection means)

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-1-232166 (JP, A) JP-A-58-25546 (JP, A) JP-A-58-135328 (JP, A) JP-A-58-135 178854 (JP, A) JP-A-56-23544 (JP, A) JP-A-55-128645 (JP, A) JP-A-6-159143 (JP, A) JP-A-9-14055 (JP, A) 55-135136 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02P 5 F02M 1/12 F02D 43/00

Claims (1)

(57) [Claim 1] PTC heater whose resistance changes with temperature
Control the power supply to the PTC heater.
Lower the plunger gradually by volume expansion of the wax.
The ignition timing control apparatus for an engine having an automatic choke apparatus which vary the mixture concentration Te, the
The auto choke device controls the power supply to the PTC heater.
Control and turn off at predetermined intervals while the engine is running.
And a transistor disposed in parallel with the transistor.
Unit resistance, and when the engine is running
While the transistor is off,
The voltage across the PTC heater based on the partial pressure ratio with the resistance
That a choke voltage detecting means for detecting the choke voltage, based on the detected choke voltage selects any of a plurality of ignition timing control map, the ignition timing based on the selected ignition timing control map An ignition timing control device for an engine, comprising: ignition timing control means for controlling.