JPH0251073B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a top dead center detection device that can easily detect the top dead center of an engine such as an automobile.

An evaluation device as shown in FIG. 1 is used. In this Fig. 1, 1 is the crankcase;
2 is the crankshaft, 3 is the crank pulley, 4
5 is the ignition timing meter, and 5 is the ignition pickup. In this evaluation device, top dead center detection of the engine is performed by placing an electromagnetic pick-up 7 for top dead center detection facing a V-shaped groove 6 as a top dead center mark carved on the crank pulley 3. be. FIG. 2 shows a signal waveform diagram of this evaluation device, where A shows the top dead center signal output from the electromagnetic pickup 7, B shows the ignition signal output from the ignition pickup 5, and H indicates the ignition advance signal generated between the output of the ignition signal and the output of the top dead center signal,
The top dead center signal is output twice during one cycle of the engine, and the time from when the top dead center signal is output until the next top dead center signal is output corresponds to 360 degrees of the crank angle. Here, a case is shown in which the ignition timing of an engine with a four-cylinder configuration is evaluated. Indicates the state in which the The ignition signal is
It is output twice during one rotation of the crank pulley 3. Here, the first cylinder and the fourth cylinder are used to evaluate the ignition advance _angle . is the time from when the ignition advance signal of the first cylinder is output until the next ignition advance signal is output, symbol T ₁ is the duration of the ignition advance signal of the first cylinder, and symbol T ₂ is the duration of the ignition advance signal of the fourth cylinder. The duration of the cylinder's ignition advance signal, the ignition advance X, is determined by the formula: X=360/T ₀ ×T ₁ +T ₂ /2 (degrees).

In this way, engine performance evaluation tests are conducted, and this conventional test has a configuration in which the electromagnetic pick-up 7 faces the V-shaped groove 6 carved in the crank pulley 3 to detect the top dead center. and
Because the mounting position of the electromagnetic pick-up 7 needs to be aligned accurately, it takes time to install the top dead center detector, and the crank pulley 3 may be damaged due to engine vibration.
This has the drawback that the facing distance of the electromagnetic pickup 7 varies, making it difficult to accurately detect the top dead center.

To evaluate engine performance during idling, an evaluation device as shown in FIG. 3 is used. When performing this idling evaluation, if top dead center is to be detected, a rotation detector 9 connected to a microcomputer 8 is attached to the crank pulley 3.
As shown in FIG. 4, the slit 9 of the rotation detector 9
A detector top dead center signal 9b is defined on a. Fifth
The figure shows the principle of determining the true top dead center of the engine from the detector top dead center signal. A is the true top dead center position of the engine, and b is the detector top dead center position determined inside the microcomputer. , C indicates the timing light signal position. The angle between the timing light signal extracted from the high tension cord of the cylinder to be measured and the top dead center mark carved on the crank pulley is A (degree), the above timing light signal is input to the microcomputer 8, and the time difference is calculated inside the microcomputer. The angle difference between the detector top dead center signal and the timing light signal obtained by
(degrees), the angular difference Y from the TDC signal of the detector at the true top dead center can be obtained by the formula Y=X+A (degrees). However, this rotation detector 9 has the disadvantage that the installation work is troublesome and time-consuming because it must be installed and removed for each engine whose performance is to be evaluated.

An object of the present invention is to provide a top dead center detection device that can easily detect the top dead center of an engine and that does not require adjustment to detect the top dead center every time the engine speed changes. Our goal is to provide the following.

The present invention is characterized by a first pulse generation circuit that generates pulses corresponding to the number of teeth during one rotation of the ring gear based on the output of an electromagnetic pickup mounted on the clutch housing so as to face the ring gear of the crankshaft. , a first counter circuit that receives pulses from the first pulse generating circuit, counts the pulses, and is turned on when the count value reaches a preset data value; a second pulse generating circuit that generates a pulse at a higher frequency than the pulse generated by the second pulse generating circuit; a gate circuit that opens when the first counter circuit is turned on when the pulse from the second pulse generating circuit is input; and the gate circuit. The pulses output from are input, the pulses are counted,
A second counter circuit that is turned on when the count value reaches the fine adjustment preset data value and outputs a pseudo top dead center signal for detecting the top dead center of the engine, and a second counter circuit that receives the pseudo top dead center signal. a timing light that outputs illumination light toward an ignition timing mark provided on the engine body, a preset data value in the first counter circuit, and a fine adjustment preset value in the second counter circuit, when and adjusting means for adjusting the output timing of the pseudo top dead center signal to coincide with the top dead center of the engine.

Then, the operation related to this configuration will be explained.

First, by initially setting the preset data value to the number of teeth of the ring gear and setting the fine adjustment preset data value to "0", a pseudo top dead center signal is output for each rotation of the ring gear. This output causes the timing light to output illumination light once for each rotation of the ring gear.

At this time, if the illumination light of the timing light and the ignition timing mark do not match, by adding "+1" to the initial preset data value using the adjustment means, a pseudo top dead end is set for each rotation of the ring gear. Since the output timing of the point signal is automatically updated by one period of the pulse corresponding to one tooth of the ring gear, the illumination light of the timing light and the ignition timing mark can be substantially matched. If the preset data values are returned to their original values when they almost match, then the true top dead center of the engine and the output timing of the pseudo top dead center signal will be in a state where they almost match.

Next, if the illumination light of the timing light and the ignition timing mark do not match exactly, update the fine adjustment preset data value by "+1" and the second counter circuit will generate the first pulse. a second pulse at a higher frequency than the pulses generated in the circuit.
By counting the pulses generated from the pulse generation circuit, the output timing of the pseudo top dead center signal is slightly shifted, so that the illumination light of the timing light and the ignition timing mark can be accurately matched. In this way, the true top dead center of the engine and the output timing of the pseudo top dead center signal can be accurately matched.

In addition, the output timing of the pseudo top dead center signal, which precisely matches the top dead center of the engine, is generated based on the rotation of the ring gear, so even if the engine speed changes, the It never deviates from top dead center.

Embodiments of the engine top dead center detection device according to the present invention will be described below with reference to the drawings.

In Fig. 6, 10 is a clutch housing;
A ring gear 11 is attached to the end of the crankshaft opposite to the end of the crankshaft to which the crank pulley is attached.
11a is a toothed portion of the ring gear 11, and 12 is an electromagnetic pickup, which is attached to the clutch housing 10 and faces the toothed portion 11a. The electromagnetic pickup 12 has a function of outputting a ring gear signal, and is connected to the top dead center detection device main body 14 via an amplifier 13.
An ignition timing meter 15 as an evaluation device is connected to the ignition timing meter 15, and an idle roughness meter 16 as an evaluation device is connected in parallel with the ignition timing meter 15.

17 and 18 are amplifiers, and each amplifier 1
7,18, ignition pick-up 19,
A timing light 20 is connected, the ignition pickup 19 has a function of outputting an ignition signal, and the timing light 20 has a function of outputting illumination light toward an ignition timing mark provided on the engine body. ing. As shown in FIG. 7, the top dead center detection device main body 14 includes a CPU 21,
ROM22, RAM23, and high-speed arithmetic element 24
It has The electromagnetic pickup 12 is the eighth
It outputs the ring gear signal shown in A in the figure.
This ring gear signal is input to the waveform shaping circuit 25 and shaped into a rectangular signal shown in FIG.
The signal is input to the first counter circuit 26. The ring gear signal pulses generated from the first pulse generation circuit composed of the electromagnetic pickup 12 and the waveform shaping circuit 25 are output in a number corresponding to the number of teeth during one rotation of the ring gear 11. It is something that will be done.

The first counter circuit 26 is turned on when a predetermined number of ring gear signal pulses are input, and the gate circuit 27 and the second counter circuit 2
8 together with a pseudo top dead center signal generation circuit that generates a pseudo top dead center signal for detecting the top dead center of the engine, and outputs this pseudo top dead center signal to the timing light 20. There is. CPU2
1 is given a preset data value so that the first counter circuit 26 is turned on when a predetermined number of ring gear signal pulses are input to the first counter circuit 26, and 29 is given a preset data value such that the first counter circuit 26 is turned on. This shows the signal line for the set data value. The position of the pseudo top dead center signal can be updated by operating the top dead center switch 30, and here, the position can be updated by the angle corresponding to the gear while the switch is pressed. The initial preset data value is the gear number digital switch 31.
For example, when the number of teeth of the ring gear is 115, it is set to "115", and the first counter circuit 26 outputs the ring gear signal corresponding to the number of teeth corresponding to the preset data value. It is turned on when a pulse is input, and turned off when a pseudo top dead center signal is output.

32 is a frequency divider, and this frequency divider 32 has:
Reference clock signal is input. The high-speed operator 24 is for determining a frequency division ratio in accordance with the engine rotation speed, and the frequency divider 32 outputs a correction pulse signal to the gate circuit 27 based on this frequency division ratio. It is something to do. The pulse of the correction pulse signal generated from the second pulse generation circuit constituted by the frequency divider 32 is for slightly shifting the timing at which the pseudo top dead center signal is output.
is a signal line for frequency division ratio. The number of teeth on the ring gear is
In the case of 103 pulses, 35 pulses of this correction pulse signal are generated at equal intervals regardless of the engine speed, and here, a pulse of the correction pulse signal is generated every 0.1 degrees in terms of crank angle. is now being output. The gate circuit 27 is
As shown in FIG. 8D, the first counter circuit 2
6 is turned on, the correction pulse signal is outputted to the second counter circuit 28. Second counter circuit 28
outputs a pseudo top dead center signal toward the timing light 20 when a predetermined number of pulses of the correction pulse signal are input, and this pseudo top dead center signal is sent to the first and second counter circuits. 26,2
8, and the first and second counter circuits 2
6 and 28 are reset, and the first and second counter circuits 26 and 28 start counting again, and E in FIG. 8 shows the waveform of the top dead center signal.
The CPU 21 is given a fine adjustment preset data value so that the second counter circuit 28 is turned on when a predetermined number of pulses of the correction pulse signal are input to the second counter circuit 28. indicates a signal line for the fine adjustment preset data value, which can be updated by the angle correction digital switch 35, and the second counter circuit 28 A pseudo top dead center signal is output when a number of correction pulse signal pulses corresponding to the data value are input. Top dead center switch 3
0 and angle correction digital switch 35 is an adjustment that controls the pseudo top dead center signal generation circuit and adjusts the output timing of the pseudo top dead center signal so that the pseudo top dead center signal matches the true top dead center signal. Next, the operation of the engine top dead center detection device according to the present invention will be explained.

Here, an example will be explained in which the ring gear 11 has 103 teeth. An initial preset data value is given to the CPU 21 by a gear number digital switch 31. If the ring gear 11 has 103 teeth, this initial preset data value is 103 teeth. At that time, the first counter circuit 26 turns on when it counts 103 pulses of the ring gear signal. When the fine adjustment preset data value is 0, the second counter circuit 28
outputs a pseudo top dead center signal at the same time as the first counter circuit 26 turns on, and the timing light 2
0 thereby outputs illumination light. At that time, if the 0 degree mark of the ignition timing mark engraved on the engine body matches the top dead center mark, it means that the time when the pseudo top dead center signal is output matches the top dead center of the engine. Therefore, this pseudo top dead center signal can be used as the top dead center signal itself. If the timing at which this pseudo top dead center signal is output does not match the top dead center of the engine, the top dead center mark and the ignition timing mark will deviate from the 0 degree. Therefore, the top dead center switch 30
When the CPU 21 operates the preset data value, the CPU 21 increments the preset data value by "+1". If the engine speed is 20 revolutions per second, the preset data value will be "+1" while the top dead center switch 30 is being operated.
Therefore, the pseudo top dead center position will be updated 20 times, which means that it will be updated 100 times in about 5 seconds. The count start position of the ring gear signal is ring gear 1.
Even if it is not known where on the tooth section 11a of the ring gear 11 it starts, if the pseudo top dead center position is updated 103 times, the count start position of the ring gear signal has made one rotation in the tooth direction of the ring gear 11. become. Therefore, by operating the top dead center switch 30, it is possible to roughly estimate whether or not the time when the pseudo top dead center signal is output coincides with the top dead center of the engine.
This can be confirmed by visually observing what time the ignition timing mark illuminated by the illumination light of the timing light 20 indicates. When the number of teeth of the ring gear 11 is 103, the interval at which the ring gear signal pulses are outputted is approximately 3.5 degrees when converted into a crank angle. In this case, the top dead center switch 30 alone cannot make the timing at which the pseudo top dead center signal is output coincide with the top dead center of the engine. Therefore, when the angle correction switch 35 is operated, the fine adjustment preset data value is updated by +1. Each time this preset data value is updated, the output timing of the pseudo top dead center signal will be shifted by approximately 0.1 degrees.
By updating the fine adjustment preset data value 35 times, it is possible to detect within a range of approximately 3.5 degrees with an accuracy of 0.1 degrees, and the illumination light 20 of the timing light 20 can be used to adjust the ignition timing mark to 0. When the degree is visually confirmed, the output timing of the pseudo top dead center signal coincides with the top dead center of the engine, and this pseudo top dead center signal can be used as the top dead center signal.

According to this embodiment, the pseudo top dead center position is automatically updated by operating the top dead center switch 30 and the angle correction digital switch 35.
It is possible to match the output timing of the pseudo top dead center signal with the top dead center of the engine within about 10 seconds.

In this way, the top dead center signal detected accurately and in a short period of time does not require the detection operation to be performed again at each engine speed even if the engine speed changes.

Figure 9 shows a block diagram of an evaluation device that evaluates engine performance using the top dead center signal obtained in this way. , T 0 is the time from the first cylinder ignition signal obtained from the ignition pickup 19 until the next first cylinder ignition signal is generated, and T ₀ is the time from the ignition signal until the top dead center signal is generated. It can also be determined by ignition advance angle x = 720 x T ₁ /T ₀ (degrees), with T 1 as T ₁ , or the top dead center signal is output after the ignition signal is generated as shown in Figure 11. By counting how many pulses of the correction pulse signal have been output during this period, and integrating the number N of pulses of the correction pulse signal with an angle of 0.1 degrees converted to the crank angle of the pulses of the correction pulse signal. can also be found. The above ignition advance value is automatically calculated by the evaluation device. In FIG. 11, A shows a correction pulse signal, B shows an ignition signal, and C shows a top dead center signal. In addition, when evaluating the engine roughness during idling, as shown in Figure 12,
The rotation speed is calculated every 20 msec, and the fluctuations in the rotation speed every 20 msec are output through statistical processing, and can be used to determine the top dead center of each cylinder. The following formula is used to calculate the rotation speed, where: R: rotation speed P: number of pulses of the ring gear signal every 20 msec K: number of teeth of the ring gear = 3000P/K 12 shows the ignition signal, and B in FIG. 12 shows the ring gear signal.

As explained in detail above, the present invention utilizes the pulse of the ring gear signal generated from the ring gear of the engine to match the output timing of the pseudo top dead center signal with the true top dead center of the engine.
The top dead center of the engine can be detected easily and accurately. Furthermore, even if the engine speed changes, the pseudo top dead center signal obtained in this way changes the output timing according to the engine speed while remaining consistent with the true top dead center. Because it does not shift,
There is no need to adjust the output timing of the pseudo top dead center signal for each engine rotation speed.

Therefore, if you want to evaluate the engine by automatically calculating the advance angle value at each engine speed and the roughness during idling based on this pseudo top dead center signal, it can be done in a short time. . By using this device, inspection work for engines at the time of shipment can be carried out efficiently and in a short time.

[Brief explanation of drawings]

Figure 1 is a conventional configuration diagram of a top dead center detection device used in an ignition timing evaluation device, Figure 2 is a signal waveform diagram of the evaluation device in Figure 1, and Figure 3 is a top dead center detection device used in an idling evaluation device. A conventional configuration diagram of a dead point detection device, Fig. 4 is a diagram assuming the top dead center position of the disk used in the evaluation device shown in Fig. 3 and a detector held inside the device, and Fig. 5 shows the evaluation of Fig. 3. A principle diagram showing the top dead center determination method in the device, FIG. 6 is an overall configuration diagram showing the top dead center detection device according to the present invention connected to an evaluation device, and FIG. 7 is a top dead center detection method according to the present invention. A configuration diagram of the main parts of the device, FIG. 8 is an output signal waveform diagram of the top dead center detection device according to the present invention, and FIG. 9 is an evaluation device for evaluating engine performance using the top dead center detection device according to the present invention. Fig. 10 is an explanatory diagram for calculating the ignition advance angle, Fig. 11 is an explanatory diagram for showing another method of determining the ignition advance angle, and Fig. 12 is an illustration for evaluating roughness during idling. This is an explanatory diagram of the process. 10...Clutch housing, 11...Ring gear, 11a...Teeth, [12...Electromagnetic pick-up, 20...Ignition pick-up, 2
5...Waveform shaping circuit] (first pulse generator), 2
6...First counter circuit, 28...Second counter circuit, 27...Gate circuit, [30...Top dead center switch, 35...Angle correction digital switch] (adjustment means), 32...Frequency divider (Second pulse generator).

Claims (1)

[Scope of Claims] 1. A first pulse generating circuit that generates pulses corresponding to the number of teeth during one revolution of the ring gear based on the output of an electromagnetic pickup attached to the clutch housing so as to face the ring gear of the crankshaft. a first counter circuit that receives pulses from the first pulse generating circuit, counts the pulses, and is turned on when the count value reaches a preset data value; a second pulse generating circuit that generates a pulse at a higher frequency than the pulse generated by the second pulse generating circuit; a gate circuit that opens when the first counter circuit is turned on by receiving the pulse from the second pulse generating circuit; The pulse output from the circuit is input, the pulse is counted, and when the count value reaches the fine adjustment preset data value, it is turned on to generate a pseudo top dead center signal for detecting the top dead center of the engine. a second counter circuit that outputs an output; a timing light that outputs illumination light toward an ignition timing mark provided on the engine body when receiving the pseudo top dead center signal; and preset data in the first counter circuit. and adjusting means for adjusting the output timing of the pseudo top dead center signal to match the top dead center of the engine by updating the value and the fine adjustment preset data value in the second counter circuit. Engine top dead center detection device.