JPS59182370A - High-resolution detector for speed of vehicle - Google Patents

Abstract

PURPOSE:To obtain a high-precision and high-resolution detector by extracting an electric signal corresponding to an engine speed from an ignition coil and increasing it to an integral multiple by a phase locked loop circuit combined with a frequency dividing circuit. CONSTITUTION:The primary-side signal of the ignition coil 1 is passed through a waveform shaping circuit 3 to remove its noise component firstly, and then the resulting signal is sent to a phase comparator 4. Two rectangular-wave pulse signals, i.e. the output of the waveform shaping circuit 3 and the output of a 1/10 frequency dividing circuit are inputted to output a current corresponding to the phase shift between both signals to an integration circuit 5. A voltage- controlled oscillation circuit 6 generates a pulse according to the output current and its frequency is divided by ten through a frequency dividing circuit 7 and fed back to the phase comparator 4. This feedback loop synthesizes a frequency which is 10 times as high as the output pulse frequency of the waveform shaping circuit 3 and the frequency is led out to the output terminal of the voltage- oscillation circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a vehicle mounted on a vehicle in order to correlate measurement data with measurement positions when making some physical measurements while the vehicle is running. The present invention relates to a device that extracts a signal corresponding to the traveling speed or distance traveled within the vehicle.

Configuration of conventional example and its problems In this type of conventional speed detection device, a rotating wire connected to a so-called speedometer is connected to an optical chopper, and the rotation of the optical chopper is extracted as an electrical signal by a photointerrupter. Commonly used. In principle, with this method, any resolution can be obtained by providing an appropriate number of holes in the optical chopper, but in reality, rotational unevenness occurs due to deflection of the rotating wire, resulting in large errors, especially at low speeds. It has been known. Furthermore, when this type of device is installed in a car, it requires modification in order to take out the rotating wire, making it difficult to use. It is also known that an optical speed sensor using a spatial filter or the like is used for this type of speed detection, but while it is easy to use, it has the problem of not being able to obtain sufficient accuracy. .

Purpose of the Invention The present invention solves these conventional problems, and is capable of detecting vehicle speed with high accuracy and high resolution over a wide speed range from low to high speeds, and which can be easily installed without the need for modifying the vehicle. The present invention provides a speed detection device for use in a vehicle.

Structure of the Invention The present inventions i and t extract an electric signal corresponding to the engine rotation speed from the primary side of the ignition coil of the engine,
After shaping the waveform of this signal, the signal frequency is increased to an integer multiple using a 7-clock loop circuit combined with a frequency divider circuit.
It outputs pulses with a sufficiently high frequency that is proportional to the vehicle speed, and extracts a high-precision, high-resolution speed signal.

Description of examples Embodiments of the present invention will be described in detail below with reference to the drawings.

In the accompanying drawings, 1 is an ignition coil of an automobile engine, 2 is a contact point, 3 is a waveform shaping circuit, 4 is a phase comparator circuit, 5 is an integrating circuit, 6 is a voltage controlled oscillator, 7 is a frequency dividing circuit, and 4 , 5, 6.7 constitute a phase-locked loop. Since the contact point 2 is opened and closed by a cam driven by the engine shaft, a pulse with a frequency proportional to the engine speed is obtained on the primary side of the ignition coil 1.

Here, if the running gear is constant, pulses with a frequency proportional to the speed, that is, a number of pulses proportional to the traveling distance will be obtained.

However, the number of pulses is determined by the total gear ratio of the vehicle's transmission mechanism, and in the case of a typical passenger car, the resolution is only about 930 degrees per pulse when running in top gear. Even higher resolution is often required when detecting vehicle speed (vehicle position) for measurement purposes. Therefore, the following signal processing is further performed. First, the signal on the primary side of the ignition coil 1 is passed through the waveform shaping circuit 3 to remove noise components, and then sent to the phase comparison circuit 4. The phase comparator circuit 4 inputs two rectangular wave pulse signals, the output of the waveform shaping circuit 3 and the output of the 1/10 frequency divider circuit, and outputs a current to the integrating circuit 5 according to the phase difference between the two signals. . The voltage controlled oscillation circuit 6 generates a pulse with a frequency corresponding to the output voltage of the integrating circuit 6, and this pulse frequency is divided by 1/10 by the frequency dividing circuit 7 and fed back to the phase comparator 4. This feedback loop allows a frequency ten times the output pulse frequency of the waveform shaping circuit 3 to be accurately synthesized and extracted from the output terminal of the voltage controlled oscillation circuit.

With this circuit configuration, pulses with a frequency ten times higher than the ignition coil pulse frequency can be obtained over a wide rotational speed range from the engine idle state to several thousand rpm. Although in principle it is not possible to continuously detect the vehicle speed from a stopped state, it is possible to detect the vehicle speed with high resolution under the condition that the vehicle is running in -S gear.

Effects of the Invention As is clear from the embodiments described above, the vehicle speed detection device according to the present invention inputs an ignition coil signal that accurately corresponds to the engine speed, so that
In principle, it is possible to detect speed with extremely high accuracy. Furthermore, the seven-step locked loop circuit combined with the frequency dividing circuit can provide a high-resolution speed signal with almost no response delay to acceleration or deceleration of an automobile. Furthermore, the vehicle speed detection device according to the present invention can be configured with several integrated circuits, and installation can be completed by simply wiring to the ignition coil, so it is extremely inexpensive and easy to install compared to various conventional methods. Yes, it is very practical as a vehicle speed detection device for measurement purposes.

[Brief explanation of drawings]

The attached drawing is a block diagram showing the configuration of a vehicle speed detection device according to an embodiment of the present invention. 1... Ignition coil, 2... Contact point, 3... Waveform shaping circuit, 4...
・・Phase comparator circuit, ・5・・・・Integrator circuit, 6・・
...Voltage controlled oscillation circuit, 7... Frequency divider circuit.

Claims (1)

[Claims] A device mounted on a car to detect the vehicle speed inside the car is equipped with a waveform shaping circuit that receives a signal from the primary side of the car's ignition coil, removes noise components contained in the signal, and outputs two input signals A. , a phase comparison circuit that outputs or absorbs current according to the phase difference between the phase comparison circuits, an integration circuit that stores the output current of the phase comparison circuit, and a voltage controlled oscillation circuit that outputs a frequency proportional to the output voltage of the integration circuit. , and a frequency dividing circuit which divides the frequency of the voltage controlled oscillation circuit and feeds it back to the input A of the phase comparison circuit, and connects the output of the waveform shaping circuit to the input B of the phase comparison circuit. A high-resolution vehicle speed detection device configured to extract speed signal pulses with increased resolution from the output terminal of a voltage-controlled oscillation circuit.