JPH04298685A - Secondary voltage sensor of ignition circuit for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a sensor capable of accurately detecting the waveform of secondary voltage applied on all spark plugs mounted on respective cylinders with simple constitution. CONSTITUTION:The secondary voltage sensor 4 of the ignition circuit of an internal combustion engine in this invention is constituted out of a columnar core part 41 made of electrical insulator, a main body 40 having a decided number of grooves 42 in the axial direction, circumferentially provided on the outer circumference of the core part, and an electric conductor 51 molded in the axis of the core part 41, all high voltage codes 21 to lead high voltage generated in an ignition coil 1 to spark plugs 3 are fitted in the grooves 42 circumferentially provided on the same cylindrical face, and induced electromotive force is generated in the electric conductor 51.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for detecting secondary voltage in an internal combustion engine equipped with a high voltage cord that guides high voltage generated by an ignition coil to a spark plug.

0002

2. Description of the Related Art In response to demands for purifying the exhaust gas of automobile engines and improving fuel efficiency, there is a need for a device that can detect the ignition state of each cylinder of the engine and take measures to prevent misfires in all cylinders. As a misfire detection device, conventionally known methods include drilling a hole in the cylinder block and attaching a combustion light sensor, attaching a pressure sensor to the mounting seat of a spark plug, and measuring the ionic current of the ignition circuit.

0003

[Problems to be Solved by the Invention] However, with the conventional method, it is difficult to determine whether a misfire has occurred during the ignition period of the ignition stroke that begins with the spark discharge of the spark plug, and it is troublesome to install. However, if installed on all cylinders of all vehicles, the installation cost would increase and maintenance would be time-consuming. An object of the present invention is to provide a sensor that can accurately detect the waveforms of secondary voltages applied to all spark plugs installed in each cylinder with a simple configuration. This detection signal is used to detect misfires, etc., and is used to control the internal combustion engine, such as purifying exhaust gas and improving fuel efficiency.

0004

[Means for Solving the Problems] The secondary voltage sensor of the ignition circuit of an internal combustion engine according to the present invention is made of an electrical insulator and has a columnar shape. It consists of a main body with a groove around it for fitting a high voltage cord leading to the main body, and a conductor molded in the center of the main body.

[0005]

Effect of the Invention In this invention, the high voltage cord constituting the secondary circuit of the ignition circuit, which is applied from the ignition coil to the spark plug via the power distributor or directly to the spark plug, is connected to a columnar body with a groove surrounding it. By fitting the spark plug into the cylinder, the conductor, which is a sensor at its center, can accurately detect the waveform of the secondary voltage applied to all the spark plugs installed in each cylinder. This detection signal is used to detect normal ignition, ignition error, and spark discharge error, and is output to control means for ignition advance, fuel injection timing, air-fuel ratio, etc. to prevent misfires.

[0006]

[Effects of the Invention] In this invention, by simply molding one conductor in the center of the main body that also serves as a clamper for high voltage wiring, all spark discharge voltages of 4 cylinders, 6 cylinders, and other single or multiple cylinders can be controlled. Can be measured accurately. Therefore, it is possible to obtain a misfire detection sensor that has a simple configuration, is easy to install, and is maintenance-free.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an ignition system 100 for an internal combustion engine that includes an ignition coil 1, a distributor 2, and a spark plug 3. A secondary voltage sensor 4 is attached to the voltage cord (plug cable) 21 and connected to a misfire detection device 5.

FIG. 2 shows a secondary voltage sensor 4 for an ignition circuit for a four-cylinder engine according to the present invention. Secondary voltage sensor 4
consists of a main body 40 having a cylindrical or square pillar core 41 and four grooves 42 formed in the axial direction at equal intervals on its outer periphery, and the conductor 51 embedded in the axis of the core 41. In this embodiment, the main body 40 is molded of plastic or rubber and also serves as a high voltage cord clamper, clamping the high voltage cord 21 to the cylinder cover of the engine.

The misfire detection device 5 includes the conductor 51 as a sensor mounted close to the high voltage cord 21 connecting the power distributor 2 and the spark plug 3, and the signal processing circuit 5.
2 and a microcomputer 53. The microcomputer 53 outputs an output to a monitor circuit M and control means N such as an engine ignition timing adjustment device, a fuel injection timing control device, and an air-fuel ratio control device.

The signal processing circuit 52 includes a clamp circuit 54 connected to the conductor, a waveform shaping circuit 55 that inputs the output of the clamp circuit 54, a counter 56 that counts the pulses output from the waveform shaping circuit 55, and the waveform shaping circuit 54. It consists of a peak hold circuit 57 that holds the level of the final pulse of the circuit 55 for a predetermined period of time, and an AD converter 58.

The operation of this secondary voltage sensor and misfire detection device will be explained with reference to FIG. The discharge voltage of the spark plug 3 is usually classified into the following patterns. A: When a spark does not fly, one large peak occurs, followed by minute voltage fluctuations. B: When spark discharge occurs normally and ignition occurs, one low peak voltage is generated, followed by a low voltage waveform containing a small number of peaks. C: When a spark discharge occurs but ignition does not occur due to a lean mixture of fuel and air, a large peak is followed by a plurality of medium and small peaks.

As a result, a single high induced voltage waveform is generated in the conductor 51 as shown at A1 when a spark discharge error occurs.
When ignition and combustion occur smoothly, one low peak voltage waveform of B1 is generated. C1 and D1
This is the waveform that occurs when there is an ignition error, in which the spark flew normally but the ignition did not occur, and multiple peak voltages of large, medium, and small occur.

The clamp circuit 54 converts the peak voltage to A
2, B2, C2, and D2. The waveform shaping circuit 55 generates the voltage waveforms A2, B2,
Among C2 and D2, the waveform above the set level is set to A3.
, B3, C3, and D3. A counter 56 counts the number of pulses within a certain period of time T1 from the ignition timing, converts it into a voltage according to the wave number, and outputs the voltage. Further, the peak hold circuit 57 holds the level of the final pulse within a certain time T1 for a time T2, and outputs A4, B4, C4,
It is output as the voltage level shown in D4. The A-D converter 58 converts these outputs into digital signals, which are analyzed by the microcomputer 53 to determine the presence or absence of ignition and the occurrence of spark failure. If there is only one pulse and the peak held voltage value is high, there is a spark discharge error. Normal ignition occurs when there are few pulses and the peak held voltage value is low. If the pulse is 2 or more and the peak held voltage value is medium, there is an ignition error.

FIG. 4 shows the secondary voltage sensor 6 of a six-cylinder engine.
shows. Other multi-cylinder engines such as 8-cylinder engines, 2-cylinder engines, 3-cylinder engines, or single-cylinder engines have similar structures. The ignition circuit may be a direct ignition type in which the high voltage generated by the ignition coil is directly guided to the spark plug, in which case 2
The high voltage generated in the secondary circuit oscillates due to the induced current following the capacitive discharge peak current, so the high voltage generated in the secondary circuit is 0.1 to 2.
A secondary voltage sensor is installed on the spark plug side where vibration components are removed by inserting a mm series gap.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an ignition device and a block diagram of a misfire detection device.

FIG. 2 is a perspective view of a secondary voltage sensor of an ignition circuit for a four-cylinder engine.

FIG. 3 is a waveform diagram for explaining the operation of the misfire detection device.

FIG. 4 is a perspective view of a secondary voltage sensor of an ignition circuit for a six-cylinder engine.

[Explanation of symbols]

1 Ignition coil 2　Power distributor 3 Spark plug 4 Secondary voltage sensor 5. Misfire detection device 40 Main body 41 Core part 42 Axial groove 51 Conductor 52 Signal processing circuit 53 Microcomputer

Claims (1)

[Claims] [Claim 1] It is made of an electrical insulator and has a columnar shape, and has a predetermined number of axial grooves around its outer periphery into which are fitted high voltage cords that guide the high voltage generated by the ignition coil to the spark plug. A secondary voltage sensor for an ignition circuit of an internal combustion engine, comprising a main body and a conductor molded in the center of the main body.