JPH0650249A - Secondary voltage waveform detecting device of gasoline engine - Google Patents

Abstract

PURPOSE:To provide the secondary voltage waveform detecting device of a DLI type ignition device of excellent mounting adaptability. CONSTITUTION:Each secondary voltage sensor 4 is constituted by buriedly providing an electrical conductive body 43 forming decided capacitance between the secondary voltage circuit in a plug cap 3 and itself within a rubber boot 40, and a plurality of the secondary sensors 4 are connected together in series by lead wires 44 and connected to a condenser so as to constitute divided voltage circuits together with the respective secondary voltage sensors. Each secondary sensor 4 is fitted in a spark plug mounting hole 10 provided on a cylinder head cover HC, a plug cap integratedly provided with an ignition coil 2 is fitted to the secondary voltage sensor 4, and it is fitted to the outside of the spark plug 1 mounted on an engine.

Description

Detailed Description of the Invention

[0001]

This invention relates to a distributorless igniter (DL) installed in a gasoline engine.
The present invention relates to a secondary voltage waveform device for detecting a secondary voltage waveform generated in a secondary circuit in an I) type ignition device.

[0002]

2. Description of the Related Art A combustion state of each cylinder can be grasped by detecting a secondary voltage waveform between electrodes of a spark plug and analyzing a decay characteristic of an electric charge charged in an electrostatic stray capacitance of the spark plug. it can. To detect the secondary voltage waveform, it is necessary to mount a sensor for detecting the secondary voltage on the secondary circuit of the ignition circuit.

[0003]

In a multi-cylinder engine equipped with a DLI type ignition device, the number of secondary voltage sensors and output lead wires is large and mounting is troublesome. An object of the present invention is to provide a secondary voltage waveform detection device for a gasoline engine, which has excellent wearability in a DLI type ignition device.

[0004]

A secondary voltage waveform detecting apparatus for a gasoline engine of the present invention is a secondary voltage waveform detecting apparatus for a DLI type ignition device, wherein a conductor is embedded in an insulator. It is installed in a spark plug mounting hole (plug hole) provided in the cylinder head cover and forms a predetermined capacitance with the secondary voltage circuit in the plug cap mounted in the spark plug mounting hole. The secondary voltage sensor includes an output lead wire for connecting a plurality of secondary voltage sensors, and a capacitor connected so as to form a voltage dividing circuit with each secondary voltage sensor.

In the secondary voltage waveform detecting device for a gasoline engine according to a second aspect of the present invention, the plurality of secondary voltage sensors are connected in series to the lead wire for output extraction, and the connector is waterproof at the tip of the lead wire. Connected to each other.

[0006]

According to the secondary voltage waveform detecting apparatus for a gasoline engine of the present invention, the secondary voltage sensor provided separately from the plug cap is mounted in the plug hole, so that the secondary voltage sensor and the plug cap are mounted. The wearability is superior to the case where and are integrated. Since the secondary voltage waveforms generated by a plurality of secondary voltage sensors have different ignition timings, the cylinder can be identified by detecting the crank angle of the engine, and the disadvantage that the detected secondary voltage waveforms overlap can be avoided. .

In the secondary voltage waveform detecting device for a gasoline engine according to the second aspect, since the secondary voltage sensor is connected in series, the lead wire can be easily routed and the lead wire and the connector are waterproofed. Is easy.

[0008]

1 shows a spark plug mounting portion of a gasoline engine equipped with a DLI type ignition device, H is a cylinder head, HC is a cylinder head cover of the engine, and 10 is a spark plug mounting hole provided in the cylinder head cover HC. (Plug hole).

Reference numeral 1 is a spark plug mounted for each cylinder, 2 is an ignition coil, 3 is a plug cap formed integrally with the ignition coil 2, and the ignition coil 2 has a plug cap 3 which is the head of the spark plug 1. It is attached by being fitted onto the part. 40 is a positioning fitted between the plug cap 3 and the spark plug mounting hole 10,
Rubber boots for insulation and cushioning, D is a diode inserted in the secondary circuit.

The ignition coil 2 includes a closed magnetic circuit type iron core 21 with a pair of fastening holes 20 for fastening to an engine, a primary coil 22, a secondary coil 23, and an electrically insulating rubber or plastic body 24 for molding these. Consists of.
A tubular portion 25 with a screw is provided on the lower surface of the body 24, and a secondary voltage terminal 26 connected to the secondary coil 23 via the diode D is provided at the center of the tubular portion 25. . Further, the iron core 21 is provided with a pair of lead holes 27 for lead wires.

The plug cap 3 is made of resin and has a cylindrical shape.
Main body 3 whose upper end is fitted onto the tubular portion 25 of the body 24
1 and a rubber cylindrical fitting portion 32 fixed to the end portion of the main body 31 and fitted on the insulator 11 of the spark plug 1 inside, and a spring connected to the secondary voltage terminal 26 inside. 33 and the electrode rod 34 are accommodated. As shown in FIG. 1, the plug cap 3 has a lower portion removably fitted to the head of the spark plug 1 and is attached to the electrode rod 3
4 is pressed against the terminal 12 of the spark plug 1 by the action of the provided spring 33 to form a secondary voltage circuit.

The rubber boot 40 comprises a tubular portion 41 formed of electrically insulating rubber and a flange portion 42 provided around the upper end of the tubular portion 41. The cylindrical portion 41 is interposed in a gap between the inner peripheral wall of the upper portion of the spark plug mounting hole 10 and the outer periphery of the upper portion of the main body 31 of the plug cap 3, and the flange portion 42.
Is the upper surface of the cylinder head cover HC and the ignition coil 2.
Is set between the bottom surface of the body 24 and the bottom surface of the body 24.

The rubber boot 40 is a secondary voltage sensor 4 in which a conductor 43 made of a metal cylinder is embedded inside the cylinder portion 41. A lead wire 44 connected to the upper end of the conductor 43 is taken out from the flange portion 42. A positioning ring 45 made of resin is fitted on the upper end of the inner circumference of the tubular portion 41. Secondary voltage sensor 4
Forms a predetermined capacitance between the conductor 43, the spring 33 of the plug cap 3, and the electrode rod 34, and a secondary voltage is detected by a voltage dividing circuit (secondary voltage waveform detection device) described later. To detect.

FIG. 2 shows a connected body of the secondary voltage sensor 4. In the 6-cylinder engine, the secondary voltage waveforms of all the cylinders can be detected by using two sets of the sensor coupling body 50 including the three rubber boots 40 connected by the lead wires 44. 46 is a connector connected to the tip (terminal) of the lead wire 44, 47 is a shield coating for noise prevention,
Reference numeral 48 represents a ground terminal of the shield coating 47.

The connection between the connector 46 and the tip of the lead wire 44 is waterproof. This waterproofness is, for example, 3 if the number of the lead wires 44 is one as in the embodiment shown in FIG.
This is extremely easy compared to the case of books. With the configuration of this embodiment, the mountability to the engine is improved, the number of sensor outputs can be reduced, and the shield wires and connectors can be saved. A four-cylinder engine preferably has a configuration in which four of the secondary voltage sensors 4 are connected by one lead wire.

FIG. 3 shows an ignition circuit of a gasoline engine equipped with the secondary voltage sensor 4 of the present invention. V is an on-vehicle power source and I is an igniter. The secondary voltage sensor 4 constitutes a secondary voltage divider 5 which is the secondary voltage waveform detection device of the present invention, with the capacitor C connected between the sensor 4 and the ground, and the divider 5 is a secondary voltage divider. It is connected to the voltage waveform detection circuit 6, and the detection circuit 6 is connected to a discrimination circuit 7 such as a microcomputer.

An on-vehicle power supply V and an igniter I are connected to the primary coil 22. The capacitor C is connected between the secondary voltage sensor 4 and the ground and has a capacitance of 3000 pF. In this embodiment, a resistor R of 3 MΩ is connected in parallel with the capacitor C to form a discharge circuit for the capacitor C.

The secondary voltage waveform detection device (voltage divider 5) applies a secondary voltage of 1/3000 to the spark discharge gap G of the spark plug 1 via the secondary voltage circuit between the diode D and the spark plug 1. Partial pressure is applied. The detection circuit 6 detects the secondary voltage waveform divided by the voltage divider 5.

The divided voltage waveform of the secondary voltage sensor 4 and the capacitor C is a waveform obtained by dividing the voltage waveform applied to the spark discharge gap G of the spark plug 3 almost as it is.
Fires when the fuel-air mixture in the cylinder of the engine ignites, when spark discharge occurs but the ignition does not occur, smoldering of the spark plug 1, performance deterioration of the ignition coil 2, voltage drop of the power supply V, etc. Among the secondary voltage waveforms applied between the electrodes of the spark plug 1, the attenuation characteristic of the secondary voltage waveform charged in the electrostatic stray capacitance of the spark plug 1 after the spark discharge is different from the case where a mistake occurs. .
By analyzing the attenuation characteristic of this secondary voltage waveform, it becomes possible to determine the state of a gasoline engine such as a missed flight, misfire, or normal ignition.

For example, when a misfire occurs in the cylinder, since there are no fuel ions in the spark discharge gap G of the spark plug 1 during combustion, the secondary voltage is slowly attenuated,
When ignited, it rapidly decays due to the presence of fuel ions.

The discriminating circuit 7 compares the characteristics of the partial pressure waveform analyzed by the detecting circuit 6 with data obtained in advance by experiments or calculations and outputs a predetermined output to the main computer for controlling the gasoline engine, or The control signal is directly output to the control means for controlling the fuel injection amount and the ignition timing.

FIG. 4 shows another embodiment. In this embodiment, the secondary voltage sensor 4 is an annular plate-shaped rubber sheet 8 interposed between the ignition coil 2 and the cylinder head cover HC, and is fixed to the rubber sheet 8 and has a spark plug mounting hole 10. And a tubular conductor 9 fitted in the. The rubber sheet 8 has a thick inner peripheral edge portion 81 that bulges up and down, and the lead wire 44 is inserted from the outer periphery and embedded. The inner peripheral edge portion 81 is compressed between the ignition coil 2 and the cylinder head cover HC as shown in the figure to seal the spark plug mounting hole 10.

The conductor 9 has a flange portion 91 whose outer periphery is embedded in the inner peripheral edge portion 81 of the rubber sheet 8, and a downward extending portion from the inner periphery of the flange portion 91, and the spark plug mounting hole 10. It has a metal cylinder 90 which is composed of a cylinder portion 92 inserted in an annular gap with the plug cap 3. Metal tube 9
The entire surface of the flange portion 91 of No. 0 is coated with a thin insulating coating 93 made of rubber, plastic, ceramic or the like except for the lead wire connecting surface. By thinning the insulating coating 93 of the conductor 9 as in this embodiment,
When the gap between the spark plug mounting hole 10 and the plug cap 3 is narrow, the secondary voltage sensor 4 can be mounted.

FIG. 5 shows still another embodiment. In this embodiment, the secondary voltage sensor 4 is provided on the outer circumference of the metal cylinder 90.
In addition to the insulating coating 93, a rubber cushion layer 94 is provided. The rubber cushion layer 94 has an insulating coating 93.
Has a function of preventing the wall surface of the spark plug mounting hole 10 from being rubbed and damaged. With this configuration, the durability of the secondary voltage sensor 4 can be improved without impairing the wearability.

[Brief description of drawings]

FIG. 1 is a perspective view showing a cross section of a secondary voltage sensor of a secondary voltage waveform detection device of the present invention.

FIG. 2 is a perspective view of a secondary voltage sensor.

FIG. 3 is a block diagram of combustion state detection of a gasoline engine.

FIG. 4 is a perspective view showing a cross section of a secondary voltage waveform detection device according to another embodiment of the present invention.

FIG. 5 is a perspective view showing a cross section of a secondary voltage waveform detection device according to another embodiment of the present invention.

[Explanation of symbols]

 1 Spark Plug 2 Ignition Coil 3 Plug Cap 4 Secondary Voltage Sensor 5 Secondary Voltage Divider (Secondary Voltage Waveform Detection Device) 6 Secondary Voltage Waveform Detection Circuit 10 Spark Plug Mounting Hole 40 Rubber Boot 43 Conductor 44 Lead Wire HC Cylinder head cover

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area F02P 15/00 303 H

Claims (2)

[Claims] 1. A secondary voltage waveform detecting device for a distributorless igniter type ignition device mounted on a gasoline engine, wherein a conductor is embedded in an insulator, and a spark plug mounted on a cylinder head cover is mounted. A secondary voltage sensor that is installed in the hole and forms a predetermined capacitance with the secondary voltage circuit in the plug cap that is mounted in the spark plug mounting hole; and a plurality of the secondary voltage sensors. A secondary voltage waveform detecting device for a gasoline engine, which comprises an output lead wire for connecting to each other and a capacitor connected so as to form a voltage dividing circuit with each of the secondary voltage sensors. 2. The secondary engine of a gasoline engine according to claim 1, wherein the plurality of secondary voltage sensors are connected in series to an output takeout lead wire, and a connector is waterproofly connected to a tip of the lead wire. Voltage waveform detector.