JPS5952964B2 - How to detect crank angle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a crank angle detection method that extracts an output that periodically changes every time a crankshaft rotates by a small fixed angle.

In many cases, various engine phenomena can be easily analyzed if they are organized in terms of crank angle.

By the way, engine tests are generally carried out with the engine supported on a support device on a surface plate, but since the engine is constantly vibrating, conventionally known general rotation angle detection methods cannot be applied as is. In other words, a slit disk with a large number of slits formed at equal pitches is fixed to the crankshaft, and the emitter and receiver are fixed on a surface plate via a fixture so that they face each other with the slit disk narrowed between them. Then, in principle, a periodic output can be obtained on the receiver every time the crankshaft rotates by one pitch of the slit, but in reality, the slit disk vibrates with the engine, so the transmitter and receiver The opposing positions of the slits change, making it impossible to obtain accurate output. In order to avoid this, it is possible to connect a rotary encoder with a built-in slit disk and emitter/receiver to the end of the crankshaft, but since the rotary encoder is also subject to constant vibration, it is necessary to have a vibration-proof structure. As a result, it is unavoidable that it becomes larger and also increases its own weight, so it is subject to restrictions on attachment to the crankshaft. Therefore, in order to consider solving the above-mentioned problems, it is conceivable to use, for example, a method similar to that of Japanese Patent Laid-Open No. 112087/1987. In other words, only the slit disk is attached to the crankshaft, and the emitter and receiver are attached to the engine case, so that the slit disk and the emitter and receiver vibrate in the same way with engine vibration, and there is no relative displacement between them. It is conceivable to detect the output even when there is no output. This will be described in detail below with reference to the drawings.

In FIG. 1, 1 is an engine, whose case 11 is supported by a support device 21 on a surface plate 2, and one protruding end 13 of a crankshaft is connected to, for example, a dynamometer (not shown). has been done. Further, a slit disk 3 is integrally fixed to the protruding end 12 of the other crankshaft, for example, by bolts. Reference numeral 4 denotes a light emitter/receiver, which is integrally fixed to the engine case 11 via a fixture 5 in such a manner that the emitter and the light receiver are narrowly opposed to each other through the slit of the slit disc 3.

5 FIG. 2 is a diagram showing an example of the slit disk 3, in which a large number of slits 31 are bored at equal pitches around the periphery, and one reference slit 32 is bored inside the slits 31. ing.

Next, FIG. 3 is a diagram showing an example of the light projector/receiver 4, in which light projectors 43, 44 and light receivers 45, 46 are fixed to opposite sides 4, 42 of the U-shaped frame, respectively. At the same time, a fixed slit plate 47 having slits at the same pitch as the slits of the slit disk 31 is fixed to the front surface of the light receiver 45. The distance between the center lines of the emitter and light receivers 43 and 45, 44 and 46 which face each other is equal to the distance between the center lines of the slit 31 and the reference slit 32 of the slit plate 3. In addition, 48 indicates these light emitter/receiver 43
This is a connector for power supply and output output to 46.
When attaching the slit disc 3 and the light emitter/receiver 4, first temporarily fix the slit disc 3 to the end of the crankshaft 12, and position the emitter/receiver 4 and the respective slits 31, 32 at opposing positions. The light emitter/receiver 4 is fixed to the engine case 11 using the fixture 5 so that the light emitter/receiver 4 is in a predetermined position.

Next, the slit disk 3 is temporarily fixed so that the reference slit 32 is at a predetermined position on the crankshaft 122, for example, at the top dead center position of the engine piston as a reference, so that the reference point output can be taken out from the light emitter/receiver 4. Adjust it to the correct position and secure it to the crankshaft 12. In this way, the emitter/receiver 4
The reference output can be extracted from the light receiver 46 or 2 each time the crankshaft 12 rotates once, and the reference output from the light receiver 47 changes periodically by the pitch of the slit 31 each time the crankshaft 12 rotates. This means that the output can be obtained.

Moreover, in such a detection method, even if the engine is vibrating, the slit disk 3 and the light emitter/receiver 4 will vibrate in the same way, so there is no risk of relative displacement occurring between them. Therefore, it is possible to perform accurate detection. However, depending on the type of engine and how it is supported, vibrations may become extremely large. There is a possibility that a vibration phase shift may occur between the two.

In order to eliminate the above-mentioned drawbacks and to reduce the length of the protrusion from the engine case to create a structure that is resistant to vibration, the present invention fixes only a small receiver to the engine case, and the projector is mounted on a narrow slit disc. and place it separately facing the receiver,
The projector is designed to cover the relative displacement between the receiver and the projector due to engine vibration, and to project a luminous flux of an appropriate area with uniform density.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

In FIG. 4, an engine 1, a crankshaft 12,] 3, a surface plate 2, a support device 21, . The slit disk 3 is similar to that shown in FIG. 1 and is arranged in the same manner.

7 is a projector, which has a support 2 facing the slit plate 3;
2 on the surface plate 2.

FIGS. 5 and 6 show an example of the projector 7, which is configured to project a light beam having a uniform density and an appropriate area onto the slit plate 3. First, in the example shown in FIG. 5, a light source 72 is placed at the bottom of the case 71, and a lens 73 is placed at the open end.The inside of the case 71 is made mirror-like by plating, for example, and the length of the case is shortened. The light from the light source 72 is reflected in various ways within the case 71 and guided to the aperture end, and the light from the light source 72 is divided into light beams with an appropriate area by the lens 73 while keeping the light density approximately uniform. It will be narrowed down and projected. Furthermore, in FIG. 6, a light source 72'' is arranged at the bottom of the case 7, and the light is introduced into a large number of minute fibers 74, and the fibers 74 are rearranged at random in the middle, and the light is emitted from the end. A lens 73'' provided at the opening end of the case 7'' condenses the light into a beam of appropriate area and projects it, and the fiber 74 equalizes the density of the light.
Reference numeral 6 in FIG. 4 is a light receiver fixed to the engine case 11 so as to receive the luminous flux projected as described above from the light projector 7 via the slit disk 3, and an example thereof is shown in FIG. . In the figure, reference numerals 6] and 62 are light receiving elements, and the slits 31 and 32 of the slit disk 3 shown in FIG.
The light receiving element 61 is fixed to a flange-like frame 64 at a distance equal to the center distance of
A fixed slit plate 63 of the same pitch is provided.
The frame body 64 is fixed to the engine case 1 by inserting bolts into attachment holes drilled in the flange portion of the frame body 64. In this way, the light receiver 6 vibrates integrally with the engine case 11, or the relative displacement with the slit disk 3 can be ignored, and the light beam from the light emitter 7 has a uniform density and an appropriate area. is projected onto the slit plate 3, so even if the engine vibrates, a constant amount of light is always projected onto the slit plate 3, making it possible to accurately detect the angle.

As described above, according to the present invention, since the light receiver is fixed to the engine case that is integrally displaced with the crankshaft to prevent relative displacement, the crank angle can be detected accurately.

[BRIEF DESCRIPTION OF THE DRAWINGS] Figure 1 is a side view of the device considered in the process of leading to the present invention, Figure 4 is a side view of the device used to carry out the invention, and Figure 2 is a side view of the device used in the same device. Front view of slit disk,
3 and 7 are structural diagrams of a light emitter and receiver used in the device, and FIGS. 5 and 6 are side views showing an example of the light projector used in the device shown in FIG. 4. . 1: Engine, 11: Case, 12, 13: Clamp shaft, 2: Surface plate, 3: Slit disk, 4: Light emitter/receiver, 6: Light receiver, 7: Light emitter.

Claims (1)

[Claims] 1. A floodlight in which a crankshaft protruding from an engine case has a number of slits drilled at equal pitches around the periphery, and a slit disk in which reference slits are drilled is fixed, and the slits are narrowed. When detecting the rotation angle of the crankshaft using a light receiver, only the light receiver is fixed to the engine case, and a light beam of an appropriate area with uniform density is directed onto the slit plate using a projector placed separately facing the slit disk. How to detect the crank angle by projecting it.