JPH0237535B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an operation detection device for intake and exhaust valves of an internal combustion engine.

Conventionally, in order to detect the operation of the intake and exhaust valves of an internal combustion engine, a part of the equipment under test is disassembled, the crankshaft is manually rotated, and the movement of the intake and exhaust valves is visually observed. In particular, this method attempts to obtain the operating timing under actual operating conditions empirically, and is not only unsuitable for checking each product, but also cannot be expected to be reliable in measurement.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an operation detection device for intake and exhaust valves of an internal combustion engine that can perform highly reliable detection under actual operating conditions and in an extremely short period of time.

In order to achieve this object, a first device based on the present invention includes a magnetic sensor provided corresponding to at least one of the intake valve and the exhaust valve, and a detection signal from the magnetic sensor that is lower than zero level. The first period from the valve opening time to the vicinity of the midpoint of the valve opening period and the middle of the valve opening period are determined by comparing the first reference signal level, which is larger than the zero level, and the second reference signal level, which is smaller than the zero level. 1st and 2nd for detecting the second period from the vicinity of the point to the valve closing timing
a comparator circuit, and a third comparator circuit that compares the detection signal using the zero level as a reference signal level.
a comparator circuit, a logic circuit that detects the opening/closing timing of the valve and the midpoint of the valve opening period from the outputs of the first and second comparator circuits, and a midpoint detection signal of the valve opening period detected by the logic circuit. and an AND gate for detecting the maximum valve lift point based on the AND of the third comparator circuit output and the third comparator circuit output.

Further, the second device based on the present invention includes a first valve provided corresponding to an intake valve and an exhaust valve, respectively.
The detection signals from the second magnetic sensor and each magnetic sensor are compared with a first reference signal level larger than the zero level and a second reference signal level smaller than the zero level, and the valve is opened from the valve opening timing. first and second comparator circuits for detecting a first period from near the midpoint of the valve period and a second period from near the midpoint of the valve opening period to the valve closing time; and a zero level as a reference signal level. a third comparator circuit that compares the detection signal;
a logic circuit that detects the opening/closing timing of the valve and the midpoint between the valve opening period from the second comparator circuit output; and a logic circuit that detects the midpoint of the valve opening period detected by the logic circuit and the third comparator circuit output; an AND gate that detects the maximum valve lift point by the logical product of The valve-opening period detection circuit and the gate circuit detecting the compression-expansion stroke period from the outputs of the first and second valve-opening period detection circuits are provided.

According to the first device based on the present invention, since the first to third comparator circuits that compare detection signals from the magnetic sensors, and the logic circuit and AND gate that process the output signals of the comparator circuits are provided, When the valve opens and when it closes,
The engine speed based on the opening/closing timing and the maximum valve lift point are determined.

According to the second device based on the present invention, in addition to having the same effect as the first device, the first device
By providing the second valve open period detection circuit and the gate circuit, it is detected that both valves are in the closed state, which corresponds to the compression and expansion stroke period.

Hereinafter, specific embodiments of the present invention will be described based on the drawings.

Figure 1 shows an example of the structure of the cylinder head of a diesel engine, where 1 is the intake valve [or exhaust valve].
It is. 2 is a push rod, which is driven by a cam mechanism connected to the timing gear train of the engine. Reference numeral 3 denotes a rocker arm rotatably mounted around a shaft 4, and when one end is pushed up by the push rod 2, the intake valve 1 at the other end resists the upward bias of the spring 5. It is pushed downward. A cover 6 covers these valve mechanisms and is made of a non-magnetic material. Reference numeral 7 denotes a magnetic sensor that is brought into contact with the outer upper surface (or side surface) of the cover 6 when detecting the operation of the valve 1.

2 and 3 show the basic configuration of the magnetic sensor 7. FIG. 2 shows the case with one detection coil, and FIG. 3 shows the case with two detection coils. In both cases, the hollow bobbin 8 and The hollow bobbin 8 has a grip portion 9 attached to one end thereof, and a permanent magnet 10 is housed inside the hollow bobbin 8. 11 and 11,
12 are individually wound detection coils, 13 and 13, and 14 are detection coils 11 and 11, 12 respectively.
These magnetic sensors 7 with sensor signal leads
The detection principle is that the magnetic field generated by the permanent magnet 10 changes due to the operation of the valve mechanism made of a magnetic material, and the detection coils 11 and 1 change according to the change.
1 and 12, and a detection signal corresponding to the movement of the intake valve 1 is generated in the sensor signal lead wire 13 or 13, 14. In the case of FIG. 3, one of the two detection coils 11 and 12 is an active coil, and the other is a dummy coil, and as shown in FIG. Balance is maintained, and a signal v corresponding to only the change in the detection signal is obtained.

FIG. 5 shows a processing circuit that processes the output signal of the magnetic sensor 7 shown in FIG. 2 to detect the opening/closing timing of the intake valve 1, the maximum valve lift point, and the rotation speed, and FIG. 7 shows the main waveforms of this circuit. Show the diagram. 16 is a differential amplifier that amplifies the output of the magnetic sensor 7 to a required amplitude. Further, 17 is a filter circuit that removes noise components from the output signal of the magnetic sensor 7 via the differential amplifier 16, thereby improving the S/N ratio. 18, 19, 20
is a comparator circuit which compiles the output signal of the filter circuit 17 [Fig. 7a] using the respective set first, second, and third reference signal levels E ₁ , E ₂ , and E ₃ as threshold levels. rate, 7th
The signal is converted into a binary signal as shown in Figures b, c, and e. Reference numeral 21 designates a logic circuit that receives the output signals of the comparator circuits 18 and 19 and a designation signal 22 that designates whether the engine is a 2-cycle or 4-cycle engine, and performs a predetermined process using a logic circuit.
Outputs two output signals, , .

The output signal [FIG. 7d] is a signal that is inverted to logic level "H" only between the falling timing of the output signal of the comparator circuit 18 and the rising timing of the output signal of the comparator circuit 19. The output signal [Fig. 7g] is a signal that is inverted to logic level "H" for a predetermined period of time at the falling edge of the output signal of the comparator circuit 19.
FIG. h] is a signal that is inverted to logic level "H" for a predetermined time at the rising edge of the output signal of the comparator circuit 18. The output signal [FIG. 7i] is produced by processing the output signal and the output signal according to the designation signal 22, and here outputs the logical sum of the output signal in response to a 4-cycle engine command. Note that the output signal here corresponds to the midpoint of the valve opening period, and the output signal corresponds to the opening and closing timings, respectively. Since the output signal consists of two signals per revolution of the engine's camshaft, this can be used to count the engine speed. Further, in FIG. 5, numeral 23 is an AND gate for detecting the timing when the valve lift reaches its maximum point, and the logical product of the output signal and the output signal [zero cross point detection signal] of the comparator circuit 20 [FIG. 7f] Detect.

In this way, in the processing circuit of FIG. 5, a signal is obtained by comparing the appropriately amplified output signal of the magnetic sensor 7 with the first, second, and third reference signal levels E ₁ , E ₂ , and E _{3 .} From this, engine speed, valve opening timing, valve closing timing, and maximum valve lift point can be detected.

FIG. 6 shows a device used to detect the position on the crank angle axis of the valve opening timing, etc. using the output signal of the AND gate 23. Here, 24 is an input terminal to which the output signal of the AND gate 23 is applied. 25 is a delay circuit,
The delay time is configured to be changeable by a delay time adjuster 26. A strobe drive circuit 27 is triggered by the output signal of the AND gate 23 via the delay circuit 25, and drives the discharge tube 28. 2
9 is the crankshaft of the tested engine, 30 is the flywheel [or pulley] directly connected to the crankshaft 29, and 31 is the specific cylinder TDC mark, indicating that the piston of the specific cylinder of the tested engine is at top dead center (TDC).
It is attached to the flywheel 30 in advance so that it coincides with the reference TDC mark 32 on the fixed side when the TDC mark is reached. Arrow A indicates the rotation direction of the flywheel 30, and 33 indicates the strobe light of the discharge tube 28.

When measuring, use the strobe light 33 to identify a specific cylinder.
The delay time of the delay circuit 25 is adjusted so that the TDC mark 31 is irradiated and the specific cylinder TDC mark 31 can be read in agreement with the reference TDC mark 32. Then, the crank angle position can be read from the operation amount of the delay time adjuster 26 at that time.

In the above embodiment, the case of the intake valve 1 was explained as an example, but the case of the exhaust valve is the same, and only the contact point of the magnetic sensor 7 is different.

In FIG. 8, a indicates a detection signal of a first magnetic sensor that is in contact with an exhaust valve, and b is a detection signal of a second magnetic sensor that is in contact with an intake valve. Further, c is a compression pressure fluctuation detection signal obtained by measuring the starter motor current during cranking, and d and e are detection signals representing the maximum lift points of the exhaust valve and intake valve, respectively, processed by the processing circuit shown in FIG.

For example, in the case of a four-cylinder engine, the waveforms of all cylinders of the compression pressure detection signal are detected. However, if the compression and expansion stroke period of the cylinder under test can be detected from the output signals of the first and second magnetic sensors, it is possible to extract only the necessary compression pressure waveform of the cylinder without using a special crank angle detection device. can.

In FIG. 9, 7a and 7b are the first and second
magnetic sensor, 16a, 17a, 16b, 17b
are a differential amplifier and a filter circuit, respectively. 3
Reference numerals 4 and 35 indicate valve opening period detection circuits, which are equivalent to the circuits including at least the reference signal levels E ₁ and E ₂ and comparator circuits 18 and 19 in FIG. A binarized signal [FIG. 8 f, g] corresponding to the period is output. 36 is an OR gate that detects the logical sum of both output signals of the comparators 34 and 35, and sends the output to the inverter 37.
through the compression-expansion stroke period [Fig. 8h]
Detect.

As explained above, according to the operation detection device for the intake and exhaust valves of an internal combustion engine of the present invention, the operation state of the valve mechanism, which is covered with a cover and cannot be visually confirmed, can be detected without disassembling the engine under test. Detection can be performed in an operating state, in a short period of time, and in a highly reliable state. Further, according to the first operation detection device of the present invention, the magnetic sensor, the comparator circuit, the logic circuit, and the AND gate are used to determine when the valve opens and closes, the engine speed, and the maximum valve lift point under the actual operating condition. It can be found by Further, according to the second operation detection device of the present invention, the compression and expansion stroke period of the internal combustion engine can be determined under actual operating conditions using the valve open period detection circuit and the gate circuit. Further, the present invention is particularly suitable for checking each product.

[Brief explanation of drawings]

The drawings show specific embodiments of the present invention, and FIG. 1 is a longitudinal section of the valve mechanism of the cylinder bed in a diesel engine and an explanatory diagram of the contact state of the magnetic sensor, and FIGS. 1. A vertical cross-sectional view of the second embodiment, FIG. 4 is a configuration diagram of the balance input circuit, FIG. 5 is a configuration diagram of the valve lift maximum point detection processing device, and FIG. 6 is a stroboscope control for detecting the crankshaft angle. The configuration diagram of the circuit, FIGS. 7a to 7i are waveform diagrams of the main parts of FIG. 5, FIGS. FIG. 2 is a configuration diagram of a compression/expansion stroke period detection processing device. DESCRIPTION OF SYMBOLS 1... Intake valve, 6... Cover, 7... Magnetic sensor, 9... Gripping part, 10... Permanent magnet, 11,1
2...Detection coil, 16...Differential amplifier, 17...
...Filter circuit, 18, 19, 20... Comparator circuit, 21... Logic circuit, 25... Delay circuit, 26... Delay time adjuster, 28... Discharge tube,
31...Specific cylinder TDC mark, 32...Reference TDC mark, 33...Strobe light.

Claims (1)

[Claims] 1. A magnetic sensor provided corresponding to at least one of an intake valve or an exhaust valve, and a detection signal from the magnetic sensor set to a first reference signal level higher than the zero level and zero. A first period from the valve opening timing to near the midpoint of the valve opening period and a second period from near the midpoint of the valve opening period to the closing timing a third comparator circuit that compares the detection signal using the zero level as a reference signal level, and a valve opening/closing timing based on the outputs of the first and second comparator circuits. a logic circuit that detects the midpoint of the valve opening period, and a logic circuit that detects the midpoint of the valve opening period, and a logical product of the midpoint detection signal of the valve opening period detected by the logic circuit and the output of the third comparator circuit to determine the maximum valve lift point. 1. An operation detection device for an intake and exhaust valve of an internal combustion engine, characterized in that it is provided with an AND gate for detection. 2 First and second magnetic sensors provided corresponding to the intake valve and the exhaust valve, respectively, and the detection signals from each magnetic sensor are set to a first reference signal level higher than the zero level and a second reference signal level lower than the zero level. The first period from the valve opening timing to near the midpoint of the valve opening period and the second period from near the midpoint of the valve opening period to the closing timing are compared with the two reference signal levels.
a third comparator circuit that compares the detection signal using the zero level as a reference signal level, and a valve opening/closing timing based on the outputs of the first and second comparator circuits. a logic circuit that detects the midpoint of the valve opening period, and a logic circuit that detects the midpoint of the valve opening period, and a logical product of the midpoint detection signal of the valve opening period detected by the logic circuit and the output of the third comparator circuit to determine the maximum valve lift point. first and second valve-open period detection circuits that respectively detect the valve-open periods of the intake valve and the exhaust valve from the detection signals from the AND gate and the first and second magnetic sensors;
1. An operation detection device for an intake and exhaust valve of an internal combustion engine, comprising a gate circuit for detecting a compression-expansion stroke period from the outputs of first and second valve-open period detection circuits.