JPH045927B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a crank angle detection device for detecting a crank angle.

Prior Art In order to perform high-precision control of marine engines, etc., it is necessary to detect the engine crank angle with high precision, and in particular, for injection start timing control, it is necessary to detect the crank angle with an accuracy of about 0.1°. .

Problems to be solved by this invention Conventionally, methods for detecting the crank angle include counting the number of teeth on a gear directly connected to the crankshaft using a photoelectric sensor, or cutting slit-like marks on the flywheel around its circumference. There were many methods to count the amount using a photoelectric sensor. With these methods, there is a limit to the accuracy of machining the slits, etc., so angles can only be detected with an accuracy of about 1°.

There is also a method of directly connecting a pulse generator or pulse encoder with a rate of about 3,600 pulses/rotation to the crankshaft, but this is not practical because it is mechanically difficult to attach and reduces reliability.

Therefore, this invention solves the above-mentioned problems when detecting the crank angle with high precision, does not require high physical precision, is easy to install, and is highly accurate. An object of the present invention is to provide a crankshaft angle detection device capable of detecting a crank angle.

Composition of the Invention The crank angle detection device according to the present invention forms detected portions at predetermined set angles in the circumferential direction of a disk whose rotation center is connected to the crankshaft, and detects the detected portions of the disk. A sensor that outputs a pulse for each of the set angles, a pulse counter that counts output pulses from this sensor and measures an angle on the order of the set angle, and outputs at least a pulse with a shorter cycle than the sensor. A high speed reference clock generator is provided, and a pulse interval counter is provided which inputs the high speed reference clock pulse and counts the number of clock pulses between the output pulses by gated every period of the output pulse of the sensor. The count value of is held in a pulse interval register, and further, a divider divides the current count value of the pulse interval counter by the count value held in the pulse interval register one cycle before, which is smaller than the set angle. The point is to calculate the order angle, and then use an adder to add the angle on the order of the set angle output from the pulse counter and the angle on the order smaller than the set angle output even from the divider to detect the crank angle. It has characteristics.

Embodiments The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 shows a control block diagram of the embodiment. Here, a disc 2 such as a gear or a flywheel is attached to the crankshaft 1, and slits 3 are cut in the circumferential direction of the disc 2 at intervals of 1°. Optical sensors 4, 4' for zero point detection and angle detection are installed at predetermined positions near the disk 2 where the brightness and darkness of the slit 3 can be detected.

As the disk 2 rotates, the angle detection optical sensor 4 outputs pulses that go low and high at 1° intervals, as shown in the first row of the time chart in FIG.
The output of this optical sensor 4 is input to an edge detection circuit 5, which is a differentiating circuit provided at the next stage, and as shown in the second stage of FIG. A pulse is output in response to the falling portion.

The output pulses of the edge detection circuit 5 corresponding to the slits 3 on the disk 2 are input to a pulse counter 6 at the next stage and the number of pulses is counted. Further, the output pulse of the zero point detection optical sensor 4' which detects only the zero point detection slit 3' which is the starting point for angle detection of the disk 2 is inputted to the pulse counter 6 as a reset signal. Therefore, each time the optical sensor 4' detects the zero point, the count value of the pulse counter 6 is reset (cleared), and the count value Nn16 corresponding to the number of slits 3 detected from the zero point is always set at each time point. output every time. In this way, the count value Nm output from the pulse counter 6 represents the crank angle in units of 1° at each time point.

Additionally, this device is equipped with a high-speed reference clock generator 8 that outputs a high-speed reference clock with a cycle much shorter than the output pulse interval of the edge detection circuit 5. It is output to the pulse interval counter 7 provided at the next stage. The pulse interval counter 7 resets (clears) the output pulse of the edge detection circuit 5.
Clock pulses t15, which are input as a signal and are gated with an interpulse time Tn13 that varies depending on the rotational speed of the crankshaft 1, are counted.

This pulse interval counter 7 is connected to the edge detection circuit 5.
When it is reset by the output pulse from , it outputs the count value t to the divider 10 and also outputs the count value t to the previous pulse interval register 9 . This previous pulse interval register 9 uses the rising part of the output pulse of the edge detection circuit 5 as a latch input, and latches the data immediately before the pulse interval counter 7 is cleared. Count value in front
When the current _cycle ends, the count value Tn is held as the value updated in the previous pulse interval register 9 for the next n+1 cycle.

Further, the count value held in the previous pulse interval register 9 is output as a reference output to the divider 10, and the divider 10 calculates t/T _o-1 to 1°.
Angles of the following order are calculated:

The calculation in this divider 10 is performed by the pulse counter 6
While the output Nm indicates the crank angle with an accuracy of 1°, angles less than 1° are indicated by the pulse interval Tn1.
3 and the elapsed time t15 from the last pulse to the current time
It is expressed as the ratio θ _0.1 =t/Tn.

By the way, since Tn is unknown at present, it can be approximately calculated as θ _0.1 =t/Tnt/T _o-1 using the previous pulse interval T _o-1 14.

Additionally, this device is equipped with an adder 11, which adds the output of the pulse counter 6 and the output of the divider 10, and calculates the angle of the crankshaft 1 with an accuracy of 1° or less as θ=Nn+t/Tn-1. , is held in the crank angle register 12 of the next stage.

This device has the above configuration, and as the crankshaft rotates, the optical sensor 4 turns on and off every 1°.
A pulse that repeatedly turns OFF is output. This pulse is differentiated by an edge detection circuit 5 and converted into minute pulses every 1°. The pulses are counted by a pulse counter 6 and the angle is measured with an accuracy of 1°.

The pulse counter 6 is an optical sensor 7 for zero point detection.
Since it is reset by the output of pulse counter 6
The data always indicate the angle from the zero point. The interval between output pulses of the edge detection circuit 5 is measured by a pulse interval counter 7 based on a reference clock faster than the pulse cycle interval. Therefore, the pulse interval counter 7 always holds the elapsed time since the last pulse input.

The contents of the pulse interval counter 7 are transferred to the previous pulse interval register 9 when the next input pulse is input, and at the same time, the pulse interval counter 7 is cleared and the elapsed time starts measuring again. By adding the contents of the pulse interval counter 7 divided by the contents of the previous pulse interval register 9 to the contents of the pulse counter 6, the desired crank angle is calculated and held in the crank angle register 12.

In this way, it is possible to detect the crank angle with an accuracy of an order of magnitude smaller than that of the conventional method using slits every 1°. This detection accuracy is defined by the relative relationship between the output pulse width of the optical sensor 4 and the output pulse number of the high speed reference clock generator 8.

In this example, we have described a method for detecting angles with an accuracy on the order of 1° or less using slits in 1° increments. can be set arbitrarily.

In this embodiment, the crank angle of a marine engine is detected, but the present invention can be widely applied to detecting the rotation angle of a mechanical press, the rotation angle of a roll in a line machine, etc.

Effects of the Invention The embodiment of the crank angle detection device according to the present invention is as described above, and the following effects can be achieved.

When detecting the crank angle, it is possible to obtain a highly accurate crank angle detection device that does not require a high degree of physical precision, can be easily installed, and is highly reliable.

[Brief explanation of drawings]

FIG. 1 is a control block diagram of the embodiment apparatus, and FIG. 2 is a time chart of FIG. 1. 1... Crankshaft, 2... Disc, 3... Slit, 3'... Zero point detection slit, 4, 4'...
Optical sensor, 5... Edge detection circuit, 6... Pulse counter, 7... Pulse interval counter, 8... High speed reference clock generator, 9... Previous pulse interval register, 10... Divider, 11... Addition vessel, 12
...Crank angle register, 13...Pulse interval of the nth cycle, 14...Pulse interval of the n-1th cycle, 15...Elapsed time from the last input pulse to the present time, 16...Pulse in the nth cycle Count number.

Claims (1)

[Scope of Claims] 1. A disc whose rotation center is connected to the crankshaft and in which detected parts are formed at predetermined set angles in the circumferential direction; a sensor that detects and outputs a pulse for each set angle; a pulse counter that counts output pulses from this sensor to measure an angle on the order of the set angle; a high-speed reference clock generator that outputs a high-speed reference clock; a pulse interval counter that inputs the clock pulses of the high-speed reference clock generator and that gates each period of the output pulse of the sensor to count the number of clock pulses between the output pulses; a pulse interval register that holds the count value of the counter one cycle before, and a pulse interval register that divides the current count value of the pulse interval counter by the count value of the previous cycle held in the pulse interval register and displays the result on the disk. a divider for calculating an angle on the order of smaller than the set angle of the detected part; A crank angle detection device equipped with an adder for addition.