JPH0517425Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a crank angle detection device for an internal combustion engine.

[Conventional technology]

In order to detect a specific crank angle, for example, the top dead center position, a rotating body is attached to the engine crankshaft, and protrusions are formed on the outer circumference of the rotating body at equal angular intervals of 45 degrees, and one of these protrusions is removed. , a first electromagnetic pick-up and a second electromagnetic pick-up are arranged around the rotating body at an angular interval of 60 degrees from each other so that they can face these protrusions, and the first electromagnetic pick-up
After the electromagnetic pick-up faces the next protrusion, the first pulse is generated after a certain period of time calculated by the computer has elapsed, and when the first electromagnetic pick-up faces the next protrusion, the generation of the first pulse is stopped. , when the second electromagnetic pickup faces the protrusion, a second pulse is generated, and when the first pulse is generated, the generation of the second pulse is stopped, and the generation of the first pulse is stopped. There is a known crank angle detection device that determines that the crank angle is a specific crank angle when the generation of the second pulse stops when the crank angle is stopped.
61-175519). When one protrusion is missing in this way, the generation form of the first pulse and the second pulse changes in the part where the protrusion is missing, so the first pulse and the second pulse can be compared as described above. Therefore, a specific crank angle can be detected.

[Problem that the invention attempts to solve]

However, in reality, sometimes the power supply to the computer is momentarily cut off, and when the power supply to the computer is momentarily cut off in this way, the signal representing the specific crank angle is no longer generated. There is a problem that injection control and ignition timing control cannot be performed. Therefore, in the past, a method has often been adopted in which a circuit external to the computer is used to generate a signal representing a specific crank angle, which is the basis for injection control and ignition timing control.

By the way, even when a signal representing a specific crank angle is generated in the external circuit of the computer, the first pulse and the second pulse with different generation forms are generated as described above, and these pulses are compared. In this way, a method of detecting a specific crank angle is a preferable method from the viewpoint of detection accuracy. However, in this case, if the first pulse and the second pulse are simply compared, there is a risk of erroneously determining that the crank angle is a specific crank angle even though it is not a specific crank angle.

[Means for solving problems]

In order to solve the above problems, the present invention includes a signal shutter having a plurality of slits and rotating together with the camshaft, and a first signal shutter disposed close to the signal shutter so as to be able to face the slits.
A plurality of first slits are provided with a detection element and a second detection element, and the slits of the signal shutter are arranged at equal angular intervals and each extend over an equal angular range, and a pair of adjacent first slits; The second slit extends over an angular range corresponding to the entire angular range between the first slits, and the first detecting element and the second detecting element are connected to the first slit.
In a crank angle detection device for an internal combustion engine, in which the crank angle is detected from the detection elements arranged at an angular interval that is an integral multiple of the angular interval of the slits, the first detection element and the second detection element are each arranged in a signal shaft. A first detection element and The second sensing element is configured such that the magnetic field acting on the magnetic field sensitive element of the second sensing element is weaker than the magnetic field acting on the magnetic field sensing element of the first sensing element, and the output of the first sensing element is set in advance. The crank angle is higher than the predetermined value and the output of the second detection element is lower than the predetermined value.

〔Example〕

Referring to FIG. 1, 1 is an engine body, 2 is a camshaft rotatably supported on the engine body 1 and rotates at the same speed as the crankshaft;
3 designates cam timing pulleys that are fitted and fixed to the end of the camshaft 2, and the cam timing pulleys 3 are positioned with respect to the camshaft 2 by a knock pin 4. The camshaft 2 projects outwardly beyond the cam timing pulley 3 to form a bearing portion 5. This bearing part 5 is the camshaft 2
and is integrally connected to the camshaft 2. In the embodiment shown in FIG. 1, the bearing part 5 is formed integrally with the camshaft 2, but the end of the cam timing pulley 3 is made to protrude beyond the camshaft 2, and the protruding end of the cam timing pulley 3 is connected to the bearing part 5. You can also. In either case, the bearing portion 5 is still integrally connected to the camshaft 2.

An inner race 7 of a double-row ball bearing 6 is fitted into the bearing portion 5, and a detection element support plate 9 is fixed to an outer race 8 of the ball bearing 6. The entire weight of the detection element support plate 9 is supported only by the bearing part 5 via the ball bearing 6, and therefore the detection element support plate 9 can freely rotate around the bearing part 5.

A disk-shaped signal shutter 10 is fitted into the inner race 7 of the ball bearing 6. A bolt 11 is screwed into the bearing portion 5, and the cam timing pulley 3, the inner race 7 of the ball bearing 6, and the signal shutter 10 are fixed to the camshaft 2 by this bolt 11. At this time, the signal shutter 10 is firmly held between the spacer 12 and the inner race 7 of the ball bearing 6. As shown in FIGS. 1 and 5, the signal shutter 10 includes a mounting portion 13 bent in two stages and a disk portion 14 extending radially outward. As shown in FIG. 5, ten first slits 18 extending over an angular range of 15 degrees are provided at 15-degree intervals on the peripheral edge of the disc portion 14;
First slits 18 and these first slits 18
A second slit 19 is formed which extends over an angular range of 45 degrees in the embodiment shown in FIG.

As shown in FIGS. 1 and 3, a bracket 20 is fixedly arranged above the cam timing pulley 3, and this bracket 20 is secured to the engine body 1 with bolts 21. As shown in FIGS. An adjustment screw 22 is screwed onto the bracket 20 so as to be movable in the circumferential direction of the detection element support plate 9. This adjustment screw 22
As shown in FIGS. 3 and 4, it has an enlarged head 23a at one end, a threaded part 23b at the other end, and a cylindrical part 2 with a uniform cross section in the middle.
3c, and the threaded portion 23b of the adjustment screw 22 is screwed onto the bracket 20. For example, a hexagonal groove 24 is formed in the enlarged head 23a of the adjustment screw 22, and by inserting a jig into the groove 24, the adjustment screw 22 can be rotated. A stopper 25 is slidably inserted into the cylindrical portion 23c of the adjusting screw 22, and a compression spring 26 is inserted between the stopper 25 and the bracket 20. On the other hand, a projection 27 that projects upward is integrally formed at the upper end of the detection element support plate 9 . This protrusion 27 has the shape of an involute gear, and one tooth surface of this protrusion 27 abuts on the inner end surface 22a of the enlarged head 23a, and the other tooth surface abuts on the inner end surface 25a of the stopper 25. The inner end surface 22a of the enlarged head 23a and the inner end surface 25a of the stopper 25 also have the shape of tooth surfaces of an involute gear.
7 is pressed onto the inner end surface 22a of the enlarged head 23a. Therefore, the protrusion 27 is held between the enlarged head 23a and the stopper 25. As a result, the projection 27 is held in contact with the inner end surface 22a of the enlarged head 23a, so the detection element support plate 9
can be reliably held at a pre-adjusted position.

As shown in FIGS. 1 and 3, a detection element holder 28 is fixedly disposed below the detection element support plate 9. As shown in FIGS. A cover 29 is attached to the detection element support plate 9 so as to cover the signal shutter 10 and the detection element holder 28. This cover 29 extends from the outside of the signal shutter 10 in the radial direction along the outer periphery of the detection element holder 28.
It extends to the vicinity of the inner end edge of the disc portion 14 . Therefore, the cover 29 and the signal shutter 10 form a mechanical seal mechanism having a labyrinth structure, and this mechanical seal mechanism can prevent dust and the like from entering the detection section.

Referring to FIGS. 1 and 2, a groove 31 for receiving the disk portion 14 is formed in the detection element holder 28. As shown in FIG. The groove 31 has a width slightly wider than the thickness of the disk portion 14, and the disk portion 14 is arranged so as not to come into contact with the inner wall surface of the groove 31. A permanent magnet 32 and a Hall element 33, which is a magnetic field sensing element, are arranged on the mutually opposing inner wall surfaces of the groove 31 so as to be able to face the slits 18 and 19 (FIG. 5) on the peripheral edge of the disk part 14. A first detection element 34 and a second detection element 37 consisting of a permanent magnet 35 and a Hall element 36 are arranged. A pair of Hall elements 33, 36
are supported on a common ceramic substrate 38 embedded within the sensing element holder 28. 1st
The detection element 34 and the second detection element 37 are arranged at an angular interval θ (Fig. 3) that is an integral multiple of the angular interval of the first slit 18, that is, 30 degrees. In the embodiment shown in FIG.
and the second detection element 37 are arranged at an angular interval of 30 degrees. As shown in FIG. 2, each Hall element 33, 36
are spaced equally apart from each other. On the other hand, each of the permanent magnets 32 and 35 has a distance between the permanent magnet 35 of the second detection element 37 and the signal shutter disc part 14. are arranged so that the distance is greater than

The Hall elements 33 and 36 generate an output voltage when a magnetic field acts on them. Therefore, when the Hall elements 33, 36 face the corresponding slits 18, 19, the magnetic fields from the corresponding permanent magnets 32, 35 act on the Hall elements 33, 36, so the output voltage of the Hall elements 33, 36 is On the other hand, when the Hall elements 33 and 36 face the disc part 14, the permanent magnet 3 is
Since the magnetic field is shielded by Hall elements 2 and 35, the output voltages of Hall elements 33 and 36 are at a low level.

FIG. 6 shows a detection circuit formed on a ceramic substrate 38. As shown in FIG. 6, this detection circuit includes waveform shaping circuits 39, 40 connected to the output terminals of each Hall element 33, 36, and an OR gate 4.
0 and an AND gate 41. One input terminal of the OR gate 40 is connected to the output terminal of the waveform shaping circuit 39, and the other input terminal is connected to the output terminal of the waveform shaping circuit 40. Further, one input terminal of the AND gate 41 is connected to the output terminal of the waveform shaping circuit 39 via the inverter 42, and the other input terminal is connected to the output terminal of the waveform shaping circuit 40. The output voltage of the waveform shaping circuits 39 and 40 becomes a low level when the output voltage of the Hall elements 33 and 36 exceeds a predetermined set voltage, and becomes a high level when the output voltage of the Hall elements 33 and 36 becomes lower than the set voltage. Become. Therefore, considering that the camshaft 2 is rotating at the same speed as the crankshaft, the output voltage of the waveform shaping circuit 39 connected to the Hall element 33 of the first detection element 34 is as shown in FIG. 7A.
As shown in , the level becomes high every 30 degrees, and no pulse is generated when facing the slit 19. On the other hand, the output voltage of the waveform shaping circuit 40 connected to the Hall element 36 of the second detection element 37 also increases to a high level every 30 degrees as shown in FIG. 5B, and no pulse is generated when facing the slit 19. . By the way, as shown in FIG. 2, the distance between the permanent magnet 35 of the second detection element 37 and the Hall element 36 is equal to the distance between the permanent magnet 32 and the Hall element 3 of the first detection element 34.
It is longer than the interval of 3. Therefore, the magnetic field that acts on the Hall element 36 when the Hall element 36 faces the slits 18 and 19 is the same as the magnetic field that acts on the Hall element 36 when the Hall element 33 faces the slits 18 and 19.
It becomes weaker than the magnetic field acting on 3. As a result, since the rise and fall of the output voltage of the Hall element 36 becomes gradual, the output pulse width of the waveform shaping circuit 40 becomes narrower than the output pulse width of the waveform shaping circuit 39, as shown in FIG.

By the way, since the first detection element 34 and the second detection element 37 are arranged at an interval of 30 degrees as described above, when the first detection element 34 faces the slit 19, the waveform of the second detection element 37 is The shaping circuit 40 generates a pulse and the second detection element 37
When the first detection element 34 faces the slit 19, the waveform shaping circuit 40 of the first detection element 34 generates a pulse. Therefore, the output terminal of the OR gate 40 becomes high level every 30 degrees as shown by C in FIG. 7, and therefore, the crank angle can be detected from the output pulse of the OR gate 40. Further, when the output voltage of the waveform shaping circuit 39 is at a low level and the output voltage of the waveform shaping circuit 40 is at a high level, the output voltage of the AND gate 41 is at a high level. In this way, the output voltage of the waveform shaping circuit 39 is at a low level and the output voltage of the waveform shaping circuit 40 is at a high level only once every 360 degrees. Therefore, from the output signal of the AND gate 41, a top dead center signal generated every 360 degrees as shown by D in FIG. 7 can be obtained. Note that if the output pulses of both waveform shaping circuits 39 and 40 are made to have the same pulse width, if these pulses deviate even slightly when both waveform shaping circuits 39 and 40 are generating pulses, the rising portion of the pulse, Alternatively, a situation occurs in which the output voltage of the waveform shaping circuit 39 is at a low level and the output voltage of the waveform shaping circuit 40 is at a high level in the falling portion of the pulse. As a result, the output voltage of AND gate 41 becomes high level, thus generating an erroneous signal. However, in the present invention, the output voltage of the waveform shaping circuit 40 always rises after the output voltage of the waveform shaping circuit 39 rises, and the output voltage of the waveform shaping circuit 40 always falls before the output voltage of the waveform shaping circuit 39 falls. The AND gate 41 does not generate the above-mentioned erroneous signal.

Note that in order to make the output pulse width of the waveform shaping circuit 40 narrower than the output pulse width of the waveform shaping circuit 39, the magnetic field acting on the Hall element 36 is
Just make it weaker than the magnetic field that acts on it. Therefore, both permanent magnets 32 and 35 are connected to the signal shutter disc portion 14.
The permanent magnet 35 is placed equidistant from the permanent magnet 3.
Even if it is formed from a weaker magnet than 2, the Hall element 3
The magnetic field acting on the Hall element 33 can be made weaker than the magnetic field acting on the Hall element 33. Further, both permanent magnets 32 and 35 are arranged at an equal distance from the signal shutter disc part 14, and a second permanent magnet is placed on the back side of the Hall element 33.
When an iron piece is inserted as indicated by a broken line 43 in the figure, the magnetic flux density passing through the Hall element 33 can be increased. As a result, in this case as well, the Hall element 36
The magnetic field acting on the Hall element 33 can be made weaker than the magnetic field acting on the Hall element 33. As described above, according to the present invention, a plurality of first slits 18 and one second slit 19 are arranged on the same circle around the rotation axis, and a pair of detection elements 34 and 37 are arranged on this same circle. By doing this, it is possible to obtain a crank angle signal that occurs every 30 degrees and a crank angle signal that occurs every 360 degrees. Therefore, both detection elements 34, 37
can be brought close to the rotational axis of the camshaft 2, so even if the installation angle of the signal shutter 10 is slightly inclined, the signal shutter 10 and the detection element 3 can be
4 and 37 can be prevented from coming into contact with each other. Furthermore, since the shape of the signal shutter 10 itself is simple, it is not only easy to manufacture, but also the signal shutter 10 can be molded with high precision, so that the signal shutter 10 and the detection elements 34, 37 can be easily manufactured. Contact can be further avoided.

Further, the positions of the permanent magnets 32, 35 and the Hall elements 33, 36 relative to the signal shutter 10 are adjusted by means of an adjusting screw 22 screwed onto the bracket 20. Since the adjusting screw 22 is disposed outside the cam timing pulley 3, the adjusting screw 22 can be easily operated, and thus the positions of the permanent magnets 32, 35 and the Hall elements 33, 36 can be adjusted very easily. It has the advantage of being Also,
Since the plate-shaped detection element supporting plate 9 is simply attached to the outside of the cam timing pulley 3, the length of the crank angle detection device in the axial direction is short, and therefore, it can be easily arranged even in a narrow engine room. Further, since the axial length is short, there is no risk of vibrations occurring, and therefore it can be applied to high-speed engines. Furthermore, since the detection element support plate 9 can be assembled by simply fitting it into the ball bearing 6, it is not only easy to install the detection element support plate 9; Since the detection element support plate 9 is supported by the support plate 9, an excessive pressing force is not generated on the detection element support plate 9 or the bearing portion 5 by attaching the detection element support plate 9, and therefore, it has excellent durability.

[Effect of idea]

According to the present invention, the first detecting element and the second detecting element are arranged at an angular interval that is an integral multiple of the angular interval of the first slit, and the first detecting element and the second detecting element are arranged at an angular interval that is an integral multiple of the angular interval of the first slit. Since the magnetic field acting on the magnetic field sensing element of the first sensing element is configured to be weaker than the magnetic field acting on the magnetic field sensing element of the first sensing element, both the first sensing element and the second sensing element face the first slit. When the output of the first detection element always rises after the output of the second detection element rises, and the output of the first detection element falls before the output of the second detection element falls. That is, even if the relative positions of the first detecting element and the second detecting element are slightly shifted, when the first detecting element and the second detecting element face the first slit, when the output of the first detecting element becomes high, The output of the second detection element always becomes high. In other words, it is impossible for the output of the second detection element to be low when the output of the first detection element becomes high.
Therefore, when the output of the first detection element is high and the output of the second detection element is low, the first detection element faces the second slit, and thus a specific crank angle can be prevented from being erroneously detected. This means that it can be detected reliably.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of the crank angle detection device and its surroundings, Fig. 2 is a plan sectional view taken along the - line in Fig. 1, Fig. 3 is a front view of the crank angle detection device, and Fig. 4 is a side sectional view of the crank angle detection device and its surroundings. Figure 1 is a side sectional view around the adjustment screw, Figure 5 is a front view of the signal shutter, Figure 6 is a front view of the signal shutter, and Figure 6 is a front view of the signal shutter.
The figure is a detection circuit diagram, and FIG. 7 is a diagram showing the output voltage of the Hall element. 2... Camshaft, 5... Bearing section, 6... Ball bearing, 9... Detection element support plate, 10... Signal shutter, 18... First slit, 19... Second
Slit, 28...Detection element holder, 32, 35
... Permanent magnet, 33, 36 ... Hall element, 3
4, 37...Detection element.

Claims (1)

[Scope of utility model registration request] The signal shutter has a plurality of slits and rotates together with the camshaft, and a first detection element and a second detection element are arranged close to the signal shutter so as to be able to face the slits. A plurality of first slits in which the slits are arranged at equal angular intervals and each extend over an equal angular range, a pair of adjacent first slits, and an angular range that corresponds to the entire angular range between these first slits. the second extending
consisting of a slit, the first detection element and the second detection element.
In the crank angle detection device for an internal combustion engine, the detection elements are arranged at an angular interval that is an integral multiple of the angular interval of the first slit, and the crank angle is detected from these detection elements. A magnet having two detection elements each disposed on one side of the signal shutter, and a magnetic field sensitive element disposed on the other side of the signal shutter and generating an output according to the strength of the magnetic field formed by the magnet. and the first detection element and the second detection element are configured such that the magnetic field acting on the magnetic field sensing element of the second sensing element is weaker than the magnetic field acting on the magnetic field sensing element of the first sensing element. , comprising an arithmetic element that generates an output representing a specific crank angle when the output of the first detection element is higher than a predetermined value and the output of the second detection element is lower than a predetermined value. Crank angle detection device for internal combustion engines.