JPS5857077A - Start-up assisting device of diesel engine - Google Patents

Abstract

PURPOSE:To make it possible to start a diesel engine without fail by continuously actuating a spark igniter until the engine reaches to a self-ignition combustion start after the stoppage of a starter motor in the diesel engine wherein the spark igniter is provided in a sub(combustion) chamber to assist the start-up of the engine. CONSTITUTION:An igniter connected to a spark plug 4 mounted on a cylinder head so as to locate a spark gap within a subchamber 2 is provided with a high voltage generating circuit 8 and an ignition controlling circuit 9, and generates an ignition signal responding to the output of a crank angle sensor 13. In the instance, an after-spark circuit 30 is further added. To this circuit 30, each output from a chilled water temperature sensor 36 and a combustion chamber temperature sensor 37 is inputted. And, the above described igniter is continuously actuated until the engine reaches to a self-ignition combustion state after the stoppage of a starter motor (starting relay 10 OFF), i.e., until the relays 44 of the sensors 36, 37 are turned off.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a starting assist device for a diesel engine using spark ignition.

As a starting aid for diesel engines, especially diesel engines with auxiliary combustion chambers such as swirl chambers and precombustion chambers,
Glow plugs are generally used. Glow plugs assist the starting of a diesel engine by compression ignition by passing an electric current through the heating element and bringing the fuel spray injected from the fuel injection valve into contact with its red-hot surface. When the temperature drops to around -25℃, even if a glow plug is used, a large current (12V x
8A) must be continuously energized before starting, the engine will not reach a state where spontaneous combustion is possible, a so-called complete explosion. In this way, conventional diesel engine starting aids using glow plugs require a preheating operation by energizing the glow plugs before operating the starter motor, which is complicated and takes a long time to complete. Moreover, since the glow plug consumes a large amount of power, the load on the battery increases, which is one of the causes of worsening fuel efficiency.

In order to solve the above problems, FIG. 1 shows an outline of a spark ignition starting assist device proposed by the present inventors. In FIG. 1, 1 is a cylinder head, 2 is a swirl chamber,
3 is a fuel injection valve, 4 is a spark plug, and the spark gap formed between the center electrode 5 and the ground electrode 6 is the swirl chamber 2.
It is attached to the cylinder head 1 so as to be located inside. 8 is a high voltage generation circuit that supplies ignition energy to the ignition plug 4 of each cylinder (the illustrated example shows the case of 4 cylinders) via a shielded high voltage cord 7; 9 is an ignition control circuit;
Reference numeral 10 designates a starting relay for opening and closing a power supply circuit of a spark ignition device comprising a spark plug 4, a high voltage cord 7, a high voltage generation circuit 8, and an ignition control circuit 9; 11 a key switch; and 12 a battery.

When the key switch 11 is placed in the 5TART position when starting the engine, a starter motor (not shown) starts operating, and at the same time, the starting relay 10 closes and supplies battery voltage to the ignition control circuit 9. The ignition control circuit 9 boosts the battery voltage to charge a capacitor (not shown) in the high voltage generation circuit 8, and also generates a crank angle 18 from a pulse generator (not shown).
180° signal generated every o° and crank angle 72o°
In response to the 720° signal generated for each cylinder, the 18°
° Outputs a trigger signal synchronized with the signal. In response to this trigger signal, the high voltage generation circuit 8 discharges the above-mentioned capacitor to flow a primary current to an ignition coil (not shown), thereby applying a high voltage generated on the secondary side of the ignition coil to the ignition lag 4 of each cylinder. The spark is applied sequentially to the fuel injector 6.
A spark ignites the fuel spray injected into the swirl chamber 2 from the vortex chamber 2 to assist in ignition of the fuel, leading to spontaneous ignition combustion.

This starting aid device using spark ignition has the advantage that it does not require preheating before starting the starter motor like a glow plug, and consumes relatively little power. When the key switch 11 is returned to the ON position (stopping the starter motor) after determining that a complete explosion has occurred due to a rapid increase in If the engine is stopped, the engine may not reach spontaneous combustion and may fail to start.

An object of the present invention is to solve the above-mentioned problems of the spark ignition starting assist device and to provide a starting assist device for a diesel engine that can reliably shift the engine to a self-igniting combustion state regardless of environmental temperature conditions. purpose.

In order to achieve the above object, the present invention includes a means for detecting the combustion state of the engine, and a spark ignition device that continues to operate the spark ignition device even after the starter motor has stopped until the detection means detects that the engine has reached the spontaneous combustion state. This means that a means for operating the system is added.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a circuit configuration diagram showing an embodiment of the present invention, in which the same reference numerals as in FIG. 1 indicate corresponding parts. This embodiment is applied to a four-cylinder engine, and as in FIG. It is installed horizontally, and together with the shielded high voltage cord 7, the high voltage generation circuit 8, and the ignition control circuit 9 constitutes a spark ignition device.

As the ignition plug, either a normal spark plug or a plasma ignition plug using creeping discharge may be used.

13 is a magnetic disk driven by a belt from a crank pulley 14 and rotates at 1/2 the speed of the crankshaft. 15 is a magnetic disk that faces a protrusion 13a provided at one location on the circumference of the magnetic disk 13 and rotates at a crank angle. 1 pulse every 720° (720°
pulse generator (electromagnetic pickup) that generates a signal),
16 is a pulse generator that faces protrusions 13b provided at 90° intervals on the circumference of the magnetic disk 160 and generates one pulse (180° signal) for every crank angle 1806; The output signals from the devices 15, 16 are respectively sent to the ignition control circuit 9 by shielded two-core cords 17, 18.

The ignition control circuit 9 includes a DC=DC converter 19 that boosts the battery voltage (12V) to several hundred V, and an ignition signal distributor 21 that operates with a voltage (for example, 8V) obtained by adjusting the battery voltage with a regulator 20. , trigger circuit 2
2 and an oscillation temporary stop circuit 26. The ignition signal distributor 21 receives 180
7 from the pulse generator 15, with the clock input as the clock input.
Using a quaternary ring counter or the like that uses a 20° signal as a reset input, every time the 180° signal increases, outputs (ignition signals for each cylinder) are generated sequentially from the four output lines, and 720° is generated.
It is designed to be reset by a signal to return to the initial state. The trigger circuit 22 converts the output of the ignition signal distributor 21 into a trigger signal suitable for firing each thyristor.

The high voltage generation circuit 8 is configured by connecting a capacitor 24.25, a thyristor 26, a diode 27.28, and an ignition coil 29 to each cylinder, and when the thyristor 26 is non-conducting -g
The output of the DC-DC converter 19 causes the diode 27 to
．． 28 to charge the capacitor 24 and trigger circuit 2
When the thyristor 26 is turned on by the trigger signal from the capacitor 2, the charge in the capacitor 24 is discharged, and one end is connected to the capacitor 2.
A current is passed through the primary side of the ignition coil 29 which is grounded through the ignition coil 29 through the ignition coil 5, thereby generating a high voltage on the secondary side of the ignition coil 29 whose one end is connected to the high voltage cord 7. The capacitor 25 has a smaller capacity than the capacitor 24, and when the capacitor 25 is charged, current no longer flows to the next side of the ignition coil, and the remaining charge in the capacitor 24 is transferred to the spark plug 4 whose discharge voltage has decreased due to the spark. The spark discharges through the guyoung.

When the capacitor 24 is discharging, the oscillation temporary stop circuit 23 is activated by the 180° signal to temporarily stop the oscillation of the DC-DC converter 19, so that the thyristor 26 is naturally extinguished at the end of the discharge.

The starting relay 10 is provided to operate the spark ignition device in synchronization with the operation of a starter motor (not shown), and when the key switch 11 is in the 5TART position,
N, and the battery voltage is supplied to the ignition control circuit 9.

3D is an after-spark circuit that is provided to continue operating the spark ignition device after the starter motor stops until the engine reaches a spontaneous combustion state, and it detects whether the engine has reached a spontaneous combustion state. It consists of an AND circuit 31 for determination, afterspark relays 32, 33, and diodes 34, 35.

The signal input to the afterspark circuit 30 is based on the temperature of one or more of the sensors that detect the combustion state of the engine, specifically, a cooling water temperature sensor, a combustion chamber temperature sensor, and an exhaust temperature sensor. Any signal from a sensor is sufficient, and this figure shows a cooling water temperature sensor 66 and a combustion chamber temperature sensor 6.
An example in which 7 signals are used in combination is shown below.

The cooling water temperature sensor 36 has a known structure that turns ON when the cooling water temperature is below a set value, and turns OFF' when it exceeds the set value.

A specific example of the combustion chamber temperature sensor 67 is one in which a temperature sensing element (for example, a thermocouple) 68 is incorporated into the center electrode 5 of the spark plug 4, as shown in FIG. The temperature sensing element 38 may be attached to the wall of a combustion chamber such as the swirl chamber 2. The internal circuit of the combustion chamber temperature sensor 37 inputs the voltage change of the temperature detection element 38 to a comparator 40 through a filter 39 that removes ignition noise, and inputs the battery voltage through resistors 41 and 42 when the key switch 11 is in the ON position. If the combustion chamber temperature is higher than the set value, it outputs a binary logic 1" signal, activates the relay 44 via the transistor 43, and turns off the contact.
' is configured to.

Signals from the ON and OFF states of the relays 44 of the cooling water temperature sensor 56 and the combustion chamber temperature sensor 37 are respectively input to the AND circuit 31 in the afterspark circuit '50.
When 4 is ON, the input signal is binary logic “0”, and when OFF
Sometimes it is set to 1''.

FIGS. 3A to 3K are time charts showing the temporal relationship of the operations of the above-mentioned parts.

As shown in the figure, when starting the engine, the key switch 11
When placed in the 5TART position, the starting relay 10 is turned on at the same time as the starter motor starts operating, and the battery 12 is turned on.
Power supply voltage is supplied from the starting relay 10 to the ignition control circuit 9. As a result, the ignition control circuit 9 and high voltage generation path 8 operate as described above, and each time fuel is injected, a spark is thrown into the spark gap of the ignition plug 4 to help ignite the fuel spray. Eventually, the driver detects a complete explosion due to a sudden increase in the engine speed and returns the key switch 11 to the ON position, which causes the starter motor to stop and at the same time, the starting relay 10 to turn OFF. However, if both the cooling water temperature and the combustion chamber temperature have not reached the predetermined level at this point, the output of the AND circuit 61 in the afterspark circuit 6o will be ``0''.
Since the relays 32 and 33 are in the ON state, the battery voltage continues to be supplied to the ignition control circuit 9 through the relay 66 and the diode 35 even after the key switch 11 is returned to the ON position. Starting assistance by the spark ignition device continues until the engine reaches a self-igniting combustion state. When the engine reaches a self-igniting combustion state, the cooling water temperature and combustion chamber temperature reach predetermined levels T4 and T, respectively.
2, and upon detecting this, the cooling water temperature sensor 36 turns OFF.
At the same time or one after another, the combustion chamber temperature sensor 37
The relay 44 is also turned off. When these two input conditions match, a potential of 1 is output from the AND circuit 31 of the afterspark circuit 30, turning off the relays 32 and 33 and stopping the operation of the spark ignition device.

Based on the above, the operating period of the spark ignition device is the operating period synchronized with the operation of the starter motor plus the operating period of the afterspark circuit, and the engine is reliably brought into a self-igniting combustion state regardless of the environmental temperature conditions. It becomes possible to do so.

As described above, according to the present invention, the spark ignition device is configured to continue operating even after the starter motor has stopped until spontaneous combustion is detected in the engine, so that the engine can be reliably made independent with a single starting operation. The practicality of the spark ignition starting aid device can be improved. Furthermore, according to the present invention, the operating period of the after-spark circuit of the spark ignition device is determined by the environmental temperature conditions, and when starting in a state where the water temperature and oil temperature are high, the operating period of the after-spark circuit can be shortened. Since power consumption can be reduced, fuel efficiency can be improved.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a conventional starting aid device using spark ignition.
FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 6 is a timing chart for explaining the operation of the device. 4... Spark plug 8... High voltage generation circuit 9
...Ignition control circuit 10...Starting relay 11...
・Key switch 30...After spark circuit 36...Cooling water temperature sensor 37...Combustion chamber temperature sensor 68...Temperature detection element Patent attorney Junnosuke Nakamura

Claims (2)

[Claims] (1) A starting assist device for a diesel engine using spark ignition, which includes a means for activating the spark ignition device in synchronization with the operation of a starter motor for driving the engine, a means for detecting the combustion state of the engine, and a means for detecting the combustion state of the engine. A starting assist device for a diesel engine, comprising means for continuously operating the spark ignition device in response to a signal after the starter motor is stopped until the engine reaches a self-igniting combustion state. (2) The detection means detects engine cooling water temperature, combustion chamber temperature,
The starting assist device for a diesel engine according to claim (1), comprising a temperature sensor that measures one or more of the exhaust gas temperatures.