JPH025079Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a crank angle detector that detects the crank angle of an engine and determines its explosion cylinder.

As a conventional engine crank angle detector, there is one shown in FIG. 1, for example. In the figure, inside the distributor housing 1,
There is a spindle shaft 2 that is driven in synchronization with the rotation of the engine. The roller 3 is mounted coaxially with the spindle shaft 2, and contacts the distributor cap 4 to send sparks to spark plugs (not shown) attached to each cylinder of the engine. Further, a slit plate 5 is fixed coaxially with the spindle shaft 2, and a phototransistor 6 is fixed to the distributor housing 1 so as to sandwich this plate. Each slit plate 5 has a
Slits are formed every 2°, 180° (for 4 cylinder engines) and 720°. By detecting these slits with the phototransistor 6, the angular position of the engine can be detected.

Conventional engine crank detectors having such a configuration have had problems in that the configuration is complex and the cost is high.

The purpose of this invention is to solve the above-mentioned problems, and the object is to provide a crank angle detector that can detect the crank angle of an engine and identify the explosion cylinder with a simple configuration.

(Summary of the invention) The engine crank angle detector according to this invention uses a piezoelectric element attached to the washer of a spark plug installed in the engine, and a detection signal from the piezoelectric element to detect the intake valve or exhaust of the cylinder of the engine. filter means for separating a signal component generated when a valve contacts a valve seat and caused by vibration of the engine; a measuring means for measuring a periodic time interval of the separated signal component; and a measuring means for measuring a periodic time interval of the separated signal component; dividing means for dividing the measured value into a predetermined number, the output of the dividing means being a value indicating the crank angle of the engine, and the detection signal of the piezoelectric element being a detection signal indicating the internal pressure of the cylinder. It is characterized by:

(Example) Hereinafter, an example of this invention will be described with reference to the drawings. FIG. 2 shows an embodiment of this invention, and shows a sectional view of an engine to which a crank angle detector is connected. In Fig. 2, 7 is the cylinder block of the engine whose crank angle is to be detected, 8 is the piston in the cylinder block 7, and 9 is the cylinder block.
This is a combustion chamber formed by block 7 and piston 8. 10 is an intake manifold that sends air into the combustion chamber 9; 11 is an exhaust manifold that exhausts exhaust gas from the combustion chamber 9; 12 is an intake valve that controls intake air from the intake manifold 10 to the combustion chamber 9; This is an ignition plug that ignites the combustion gas in the combustion chamber 9.

Furthermore, in this invention, the ignition plug washer type piezoelectric element 21, which is a component thereof, is attached to the cylinder block 7 as a washer for the ignition plug 13. The spark plug washer type piezoelectric element 21 generates a detection signal that changes the voltage in response to the vibration of the cylinder block 7 and changes in its internal pressure, and sends this detection signal to the crank angle detector 15, which is a component of this invention. I am typing.

See Figure 3. FIG. 3 is a block diagram showing details of the crank angle detector 15. The detection signal of the spark plug washer type piezoelectric element 21 is input to a high pass filter (HPF) 16. high pass
The filter 16 extracts a high frequency signal component corresponding to the vibration of the engine and inputs it to the comparator 17. A comparator (COMP) 17 compares the high frequency signal component extracted by the high pass filter 16 with a predetermined level (for example, 0 volt level), and when it exceeds this predetermined level,
This makes the output high level.

The output of the comparator 17 is input to a bistable multivibrator 18. When the output of comparator 17 goes high, bistable multivibrator 18 is triggered to invert the logic state of its output. Bistable multivibrator (FF) 18
The output is input to the counter 19 (CNT).

Here, the counter 19 may be a known one,
For example, any device that counts a clock signal may be used.The time interval during which the pulse output from the bistable multivibrator 18 is at high level and low level is counted by the clock signal, and the counted result is sent to the divider. Enter (DIV) 20. The divider 20 may also be a known frequency dividing circuit, and divides the count result of the count 19 by a number related to the crank angle to output a signal representing the engine crank angle.

Next, the operation of this embodiment will be explained. Referring again to FIG. Air taken into the combustion chamber 9 is taken into the combustion chamber 9 via the intake manifold 10 when the piston 8 descends and the intake valve 12 opens. After the piston 8 passes through the bottom dead center and rises, the intake valve 12 contacts the valve seat of the cylinder block 7, as shown, and the combustion chamber 9 is closed. Next, when the piston 8 approaches the top dead center, the spark from the ignition plug 13 causes the mixed gas in the combustion chamber 9 to explode. Thereafter, an exhaust valve (not shown) opens, and the burned gas in the combustion chamber 9 is exhausted via the exhaust manifold 11.

Engine vibrations and internal pressure changes that occur when the mixed gas in the fuel chamber 9 explodes due to the spark from the ignition plug 13 are transmitted to the ignition plug washer-type piezoelectric element 21 via the washer of the ignition plug 13. Ru. Therefore,
When the ignition plug washer type piezoelectric element 21 is attached to the No. 1 cylinder, the detection signal detected thereby includes vibrations generated when the intake valve contacts the valve seat.

Next, reference is made to FIGS. 3 and 4. The detection signal of the spark plug washer type piezoelectric element 21, as shown in FIG. and is input to the high pass filter 16. The high pass filter 16 extracts only the vibration component of the high level cylinder block 7 having a relatively high frequency from the detection signal of the spark plug washer type piezoelectric element 21, and generates the vibration component as shown in FIG. Outputs a vibration wave signal. The output signal of the high pass filter 16 is input to a comparator 17, where it is compared with a predetermined level and converted into a pulse signal as shown in FIG. 4C. This pulse signal is input to the bistable multivibrator 18, and the bistable multivibrator 1
8 is triggered. Therefore, the bistable multivibrator 18, as shown in FIG.
2 generates a pulse signal with inverted voltage polarity each time it contacts the valve seat. counter 19
inputs this pulse signal from the bistable multivibrator 18, and counts the high level period and low level period using a clock signal (not shown). That is, by counting the time intervals of the pulses of the comparator 17 with the counter 19, a count value that increases triangularly is obtained. The maximum value of the count value represents the time interval at which the intake valve 12 contacts the valve seat, as shown in FIG. 4E. Therefore, this count value is divided by an arbitrary number related to the crank angle in the divider 20, for example 720, to obtain the crank angle for every 1 degree. Furthermore, in the case of a four-cylinder engine, dividing the count value of the counter 19 by 4 yields a value corresponding to the explosion process, which can also be used to determine the explosion process.

Since the detection signal of the spark plug washer type piezoelectric element 21 represents the pressure inside the cylinder block 7,
It can also be used for that measurement.

In the embodiment described above, a case has been described in which vibrations are detected when the intake valve 12 contacts the valve seat, but it is also possible to detect vibrations when the exhaust intake valve contacts its valve seat.

As explained above, according to this invention, a specific vibration is detected from various vibrations in the cylinder block using a piezoelectric element attached to the cylinder block of the engine, and the period of the vibration is determined by a predetermined appropriate number. Since the crank angle can be detected by dividing, the structure of the crank angle detector can be simplified, which has the effect of reducing its manufacturing cost.

Furthermore, it is possible to easily identify the explosion cylinder and measure the pressure inside the cylinder block from such detected vibrations.

[Brief explanation of the drawing]

Figure 1 is an exploded perspective view of a conventional crank angle detector for an engine, Figure 2 is a vertical sectional view of an engine equipped with a crank angle detector that is an embodiment of this invention, and Figure 3 is the same as Figure 2. 4 is a block diagram showing details of the crank angle detector shown in FIG. 4, and FIG. 4 is a waveform diagram of output signals of each part shown in FIG. 7; cylinder block; 15; crank angle detector; 16; high pass filter; 17; comparator; 18; bistable multivibrator; 19; counter; 21; spark plug washer type piezoelectric element.

Claims (1)

[Claims for Utility Model Registration] A piezoelectric element attached to the washer of a spark plug installed in an engine, and a detection signal from the piezoelectric element that determines when an intake valve or an exhaust valve of a cylinder of the engine comes into contact with a valve seat. filter means for separating signal components generated and caused by vibrations of the engine; measuring means for measuring periodic time intervals of the separated signal components; and measuring the measured values of the measuring means by a predetermined number. a dividing means for dividing, the output of the dividing means being a value indicating the crank angle of the engine, and the detection signal of the piezoelectric element being a detection signal indicating the internal pressure of the cylinder. Detector.