JPH04285861A - Electromagnetic pickup - Google Patents

Abstract

PURPOSE:To eliminate the shield wire connecting an electromagnetic pickup and an engine control unit. CONSTITUTION:A waveform shaping processing circuit 7 shaping a signal waveform detected by a coil 6 to obtain a required signal waveform is built in the electromagnetic pickup of an engine control system constituted of the rotor 1 connected to the rotary shaft directly connected to an engine and having teeth 5 provided to the outer periphery thereof, the electromagnetic pickup 2 arranged in opposed relation to the rotor 1 and having the coil 6 detecting the movement of the teeth 5 built therein, an engine control unit 3 controlling the engine on the basis of the signal from the electromagnetic pickup 2 and the wire harness 4 connecting the electromagnetic pickup 2 and the engine control unit 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic pickup for a system that detects the rotational speed and timing of an engine using an electromagnetic pickup and controls the engine based on the detected rotational speed.

0002

[Prior Art] In recent years, as in the invention described in Japanese Unexamined Patent Publication No. 64-63814, the state of the engine is detected by various sensors in order to perform electronic control of the engine, and air-fuel ratio control, ignition timing control, etc. It is carried out. Of these,
The rotation speed sensor detects the engine rotation speed, the crank angle sensor detects the crank angle, and the cam angle sensor detects the cam angle. They are installed close to a shaft directly connected to the engine, such as a crankshaft, camshaft, or distributor shaft. An electromagnetic pickup is used.

[0003] This electromagnetic pickup is attached to a crankshaft or the like, facing a toothed rotor (signal disk plate), and has a built-in coil.When the engine rotates, the teeth of the rotor act as an electromagnetic pickup. When passing near the coil, the magnetic flux in the coil changes and a signal waveform is output. Based on this output, the engine control device detects engine speed, crank angle, cylinder discrimination, cam angle, etc.

FIG. 4 shows a schematic diagram of a conventional engine control system using an electromagnetic pickup. This engine control system includes a rotor 11 connected to a crankshaft 21 of an engine body 20, an electromagnetic pickup 12 disposed opposite to the rotor 11, and an electromagnetic pickup 12.
an engine control device 13 that controls the engine based on signals from the electromagnetic pickup 12 and the engine control device 1;
3 and a wire harness 14 that connects the 3.

FIG. 2 shows the configuration of the conventional engine control system described above. Rotor 11 of this engine control system
is provided with teeth 15 on its outer periphery, and the electromagnetic pickup 12 has a built-in coil 16 for detecting the rotation of the engine. Furthermore, inside the engine control device 13,
A waveform shaping processing circuit 17 that processes the signal waveform output by the coil 16, a microcomputer 18 that detects engine speed, crank angle, cylinder discrimination, cam angle, etc. from the processed signal waveform, and waveform shaping processing for these. A constant voltage power supply 19 for driving a circuit 17 and a microcomputer 18 is built-in.

[0006] The signal waveform of this coil 16 provides an output exceeding 100V when the engine is rotating at high speed.
At low speed rotation, only an output of about several tens of mV can be obtained. On the other hand, ignition noise for engine ignition is present in the engine room where the electromagnetic pickup 12 and the engine control device 13 are housed. Therefore, the weak voltage from the coil 16 during low speed rotation is buried in the ignition noise and is difficult to detect. Therefore, as a countermeasure against ignition noise, a shielded wire is used in the wire harness 14 that connects the electromagnetic pickup and the engine control device. however,
This shielded wire is expensive, leading to an increase in component costs.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an engine control system that can take measures against ignition noise without using expensive shielded wires that increase component costs.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the present invention incorporates a waveform shaping processing circuit, which was conventionally built into an engine control device, into an electromagnetic pickup. a rotor connected to a rotary shaft and having teeth on its outer periphery, an electromagnetic pickup disposed opposite to the rotor and having a built-in coil, and an engine control device that controls an engine based on signals from the electromagnetic pickup. , an electromagnetic pickup used in an engine control system comprising a wire harness connecting the electromagnetic pickup and the engine control device, the electromagnetic pickup further having a signal waveform detected by the coil as a desired signal waveform. An invention is provided in which an electromagnetic pickup is characterized in that it has a built-in waveform shaping processing circuit for shaping the waveform.

[0009]

[Operation] In the electromagnetic pickup according to the present invention, even in the case of a weak alternating current signal during low speed rotation, it is possible to
Since it is possible to transmit the pulse wave to the engine control device after converting it into a pulse wave of approximately 5 V (for example, 5 V), a sufficient S/N ratio can be ensured without using an expensive shielded wire.

0010

Embodiment Next, an embodiment of an engine control system using an electromagnetic pickup according to the present invention will be described with reference to FIG. The outline of this engine control system is basically the same as the conventional engine control system shown in FIG. an electromagnetic pickup 2,
It is comprised of an engine control device 3 that controls the engine based on signals from the electromagnetic pickup 2, and a wire harness 4 that connects the electromagnetic pickup 2 and the engine control device 3.

Teeth 5 are provided on the outer periphery of the rotor 1 . The electromagnetic pickup 2 includes a coil 6 for detecting the movement of the teeth 5, and a waveform shaping processing circuit 7 for shaping the signal waveform detected by the coil 6 into a desired waveform. The engine control device 3 also includes a microcomputer 8 that calculates engine speed, crank angle, cylinder discrimination, cam angle, etc. based on signals transmitted from the electromagnetic pickup 2, and a constant voltage power source for driving the microcomputer 8. 9 is built-in. Therefore, the output signal from the electromagnetic pickup can always be a pulse wave at a constant level (for example, 5V, which is the TTL level used in microcomputers), and it is not affected by ignition noise even without using a shielded wire. The wire harness 4 is not a conventional shielded wire, but a vinyl wire commonly used in automobiles.

FIG. 3 is for explaining the operation of the electromagnetic pickup according to the present invention, in which (a) shows the output waveform of the coil 6, and (b) shows the output waveform of the waveform shaping processing circuit 7. As shown in (a), the output of the coil 6 is small when the engine rotation speed is low, and large when the engine rotation speed is high. Therefore, at low speeds, if left as is, it will be buried in the engine ignition noise. On the other hand, as shown in (b), since it is not affected by noise, the output of the waveform shaping processing circuit remains constant both during low speed rotation and high speed rotation. In this way, the output signal from the electromagnetic pickup is always a pulse wave at a constant level (for example, 5V, which is the TTL level used in microcomputers), and there is no need to use a shielded wire. This waveform shaping processing circuit can also be integrated into an IC so as to be built into an electromagnetic pickup.

[0013]

[Effects of the Invention] As explained above, since the electromagnetic pickup of the present invention has a built-in waveform shaping processing circuit, the signals transmitted through the wire harness are not affected by noise, so there is no need for expensive shielded wires. Improves signal reliability even when not used. Therefore, it is possible to reduce component costs.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an engine control system using an electromagnetic pickup of the present invention.

FIG. 2 is an explanatory diagram of an engine control system using a conventional electromagnetic pickup.

FIG. 3 is an explanatory diagram of the operation of the electromagnetic pickup of the present invention.

FIG. 4 is a schematic diagram of a conventional example of an engine control system using an electromagnetic pickup.

[Explanation of symbols]

1 Rotor 2 Electromagnetic pickup 3 Engine control device 4 Wire harness 5 Teeth 6 Coil 7 Waveform shaping processing circuit 8. Microcomputer 9 Constant voltage power supply

Claims (1)

[Claims] Claim 1: A rotor that is connected to a rotating shaft that is directly connected to an engine and has teeth on its outer periphery; an electromagnetic pickup that is disposed opposite to the rotor and has a built-in coil; An electromagnetic pickup used in an engine control system including an engine control device that controls an engine, and a wire harness that connects the electromagnetic pickup and the engine control device, the electromagnetic pickup further having a wire detected by the coil. An electromagnetic pickup characterized by having a built-in waveform shaping processing circuit that shapes a signal waveform into a desired signal waveform.