JP2008111763A - Rotation direction discrimination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To discriminate a rotation direction of a rotating shaft in an extremely short time. <P>SOLUTION: The first rotor plate 14 is fixed integrally at a prescribed interval with a crank shaft 12 of an engine 10 which is a rotation direction discrimination object, and the second rotor plate 16 is fixed loosely rotatably. Each slit extending in the radial direction is formed at each prescribed angle on the first and second rotor plates 14, 16, and a projection piece 14B and an engaging hole 16B with which its tip part is to be engaged are formed in order to regulate a relative rotation angle of the second rotor plate 16 to the first rotor plate 14 between an overlapping position of each slit and a not-overlapping position. A photoelectric sensor 18 for outputting a pulse signal corresponding to a state whether each slit is overlapped or not following its rotation is disposed in the facing state to the first and second rotor plates 14, 16, and a rotation direction of the crank shaft 12 is discriminated based on the pulse signal by a control program executed by a control unit 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for determining a rotation direction of a rotation shaft.

For the purpose of discriminating the rotation direction of the rotation shaft, as described in Japanese Patent Laid-Open No. 8-86796 (Patent Document 1), the tooth portion protruding from the outer periphery of the rotor rotating in synchronization with the rotation shaft A technique has been proposed in which the rotation direction is discriminated based on a differential signal obtained by differentiating the output from the sensor.
JP-A-8-86796

  By the way, when the engine rotates in reverse, fuel injection, ignition, and the like are not performed at an appropriate timing. For example, output torque and exhaust properties may be reduced, and backfire may occur. For this reason, it is necessary to determine the rotation direction of the engine. However, since the conventional proposed technique requires a certain amount of time to determine the rotation direction of the crankshaft or the like, it is difficult to eliminate these problems. .

  Therefore, in view of the conventional problems as described above, the present invention is provided with two rotating plates formed with slits extending in the radial direction substantially in parallel, and slits that are shifted in accordance with the rotation direction of the rotation direction determination target. An object of the present invention is to provide a rotation direction discriminating apparatus capable of discriminating the rotation direction in an extremely short time from an overlapped state.

  Therefore, in the first aspect of the invention, at least one slit extending in the radial direction is formed, and the slit is relatively rotatable between the overlapping position and the non-overlapping position. Two rotating plates, a sensor disposed opposite to the plate surfaces of the two rotating plates and outputting a signal according to whether or not the slits overlap, and the direction of rotation based on the signals from the sensors And one of the two rotating plates is fixed perpendicularly to the rotation axis of the rotation direction discriminating target.

According to a second aspect of the present invention, the two rotating plates are formed with a projecting piece projecting from one to the other and an engaging hole with which the tip end of the projecting piece is engaged. Thus, it is configured to be relatively rotatable between two positions.
According to a third aspect of the present invention, a plurality of the slits are formed at predetermined angles over the entire circumference of the two rotating plates.

  According to a fourth aspect of the present invention, the sensor comprises a photoelectric sensor provided with a light projecting element that emits light and a light receiving element that receives the light.

  According to the first aspect of the present invention, one of the rotating plates rotates in synchronization with the rotating shaft whose rotation direction is to be determined. Since the other rotating plate can be relatively rotated between the position where the slit overlaps with the one rotating plate and the position where the slit does not overlap, the other rotating plate is indirectly rotated by the one rotating plate. For this reason, the relative rotational state of the two rotary plates changes according to the rotational direction of the rotational axis to be determined for the rotational direction, and the two rotary plates rotate with the slits overlapped or with no slits overlapped. . Since the overlapping state of the slits is detected by the sensor, the rotation direction can be determined based on the output signal. At this time, since the rotation direction can be determined in a very short time after the rotation axis of the rotation direction determination target starts rotating, for example, if the present invention is applied to determine the engine rotation direction, the exhaust property Reduction and occurrence of backfire can be reliably eliminated.

According to the second aspect of the present invention, since the other rotating plate is rotated through the protruding piece of the one rotating plate, the position where the slits overlap and the position where the slits do not overlap without using a complicated mechanism. The two rotating plates can be easily rotated relative to each other.
According to the third aspect of the present invention, since a plurality of slits are formed at predetermined angles over the entire circumference of the two rotary plates, the present invention is incorporated into, for example, a rotational speed detection device that detects the engine rotational speed. be able to.

  According to the fourth aspect of the present invention, since it is sufficient that the light receiving element can receive the light projected from the light projecting element, it is not necessary to keep the distance between the two rotating plates at a minute distance, and the required accuracy decreases. Cost reduction can be achieved.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a configuration in which a rotation direction determination device according to the present invention is incorporated in a rotation speed detection device for the purpose of determining the rotation direction of an engine.
A first rotary plate 14 is integrally fixed to the crankshaft 12 of the engine 10 at a predetermined interval so that the plate surface is positioned on a plane perpendicular to the rotation center, and the second rotary plate 14 The rotating plate 16 is fixed freely. Each of the first rotating plate 14 and the second rotating plate 16 has a substantially disc shape having the same diameter, and as shown in FIG. 2, a slit extending in the radial direction over the entire circumference in the circumferential direction. A plurality of 14A and 16A are formed for each predetermined angle.

  Further, as shown in more detail in FIG. 3A, the first rotating plate 14 is formed with a protruding piece 14B having a substantially rectangular shape protruding toward the second rotating plate 16. The protruding piece 14B can be formed, for example, by forming a substantially U-shaped cut on the plate surface of the first rotating plate 14 and bending the cut. On the other hand, the second rotary plate 16 is formed with an engagement hole 16B that engages with the tip of the protruding piece 14B in order to regulate the relative rotation angle with respect to the first rotary plate 14. When the engagement holes 16B are seen from the direction perpendicular to the plate surfaces of the first rotating plate 14 and the second rotating plate 16, the slits 14A and 16A are overlapped as shown in FIG. It is formed between a position A where the projecting piece 14B contacts the engaging hole 16B and a position B where the projecting piece 14B contacts the engaging hole 16B when the slits 14A and 16A do not overlap and overlap. . Here, in order to detect the engine rotation speed, the formation position of the engagement hole 16B is determined so that the slits 14A and 16A overlap when the engine 10 is rotating in the correct direction. Note that the protruding piece 14B is not limited to a substantially rectangular shape, and may be composed of, for example, a rod member having a substantially cylindrical shape.

  In this way, when the crankshaft 12 rotates with the operation of the engine 10, the first rotating plate 14 integrated therewith rotates in synchronization. On the other hand, since the second rotating plate 16 is fixed to the crankshaft 12 so as to be free to rotate, the second rotating plate 16 is rotated via the protruding piece 14B of the first rotating plate 14. At this time, if the engine 10 is rotating in the correct direction, as shown in FIG. 3B, the protruding piece 14B comes into contact with the engagement hole 16B at the position A, so that the slits 14A and 16A overlap each other. Become. On the other hand, if the engine 10 is rotating in the reverse direction, as shown in the figure, the protruding piece 14B comes into contact with the engaging hole 16B at the position B, so that the slits 14A and 16A are shifted. For this reason, it is possible to determine in a very short time whether or not the engine 10 is rotating in reverse by a control system described below.

  And as a control system, if the slits 14A and 16A are opposed to the plate surfaces of the first rotating plate 14 and the second rotating plate 16, they output a pulse signal corresponding to their rotational speed. Is disposed. Here, a photoelectric sensor 18 having a light projecting element 18A that projects light and a light receiving element 18B that receives the light is used as a sensor. If the photoelectric sensor 18 is used as a sensor, it is sufficient that the light receiving element 18B can receive the light projected from the light projecting element 18A. Therefore, the distance between the first rotating plate 16 and the second rotating plate 18 is set to a minute distance. There is no need to maintain the cost, and the cost can be reduced as the required accuracy decreases. The sensor is not limited to the photoelectric sensor 18, and a proximity sensor using a magnet or the like can be used.

  A control unit 20 incorporating a computer is provided to control the light projecting element 18A of the photoelectric sensor 18 and to process a signal from the light receiving element 18B. The control unit 20 executes a control program stored in a ROM (Read Only Memory) or the like, thereby detecting the rotational speed of the engine 10 and determining the rotational direction. Further, in the control unit 20, when the engine 10 is rotating in the reverse direction, the fuel injection device 22 is controlled to stop the engine 10 for the purpose of preventing deterioration of exhaust properties and occurrence of backfire.

The control unit 20 executes the control program so that the rotation direction discriminating means is realized. In order to stop the engine 10, an ignition device that ignites a mixture of air and fuel may be controlled instead of the control of the fuel injection device 22.
FIG. 4 shows the processing contents of the control program executed in the control unit 20 when the engine 10 is started.

In step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), a pulse signal is read from the photoelectric sensor 18.
In step 2, it is determined whether or not a pulse signal is input. If the pulse signal is input, the process proceeds to step 3 (Yes), the rotational speed of the engine 10 is calculated by a known technique, and the process returns to step 1. On the other hand, if no pulse signal is input, the process proceeds to step 4 (No), and a fuel injection stop command is output to the fuel injection device 22 to stop the engine 10.

  According to this rotational speed detection device, when the engine 10 is rotating in the correct direction, the slit 14 </ b> A of the first rotating plate 14 and the slit 16 </ b> A of the second rotating plate 16 rotate in an overlapping state. Therefore, as shown in FIG. 5A, the light projected from the light projecting element 18A of the photoelectric sensor 18 passes through the slits 14A and 16A and is received by the light receiving element 18B. Therefore, a pulse signal corresponding to the rotational speed of the engine 10 is output from the light receiving element 18 </ b> B to the control unit 20. On the other hand, when the engine 10 is rotating in the reverse direction, the slit 14A of the first rotating plate 14 and the slit 16A of the second rotating plate 16 are rotating in a shifted state, so that FIG. As described above, the light projected from the light projecting element 18 </ b> A of the photoelectric sensor 18 is blocked by the second rotating plate 16.

  Therefore, by determining whether or not a pulse signal is output from the photoelectric sensor 18, it can be determined in a very short time whether or not the engine 10 is rotating in reverse. When the engine 10 is rotating in the correct direction, the rotation speed is calculated. When the engine 10 is rotating in the reverse direction, the engine 10 is operated to prevent deterioration of exhaust properties and occurrence of backfire. Stopped.

  In the present embodiment, the present invention is applied to the rotational speed detection device, but may be implemented alone. In this case, it is sufficient that at least one radially extending slit is formed in the first rotating plate 14 and the second rotating plate 16, and the sensor depends on whether the slits overlap. It is sufficient if it can output the correct signal. Furthermore, the rotational direction discrimination target is not limited to the engine rotational direction, and may be anything.

Overall configuration diagram incorporating the present invention in a rotational speed detection device The details of the first rotating plate and the second rotating plate are shown, (A) is a plan view of the first rotating plate, (B) is a plan view of the second rotating plate. The engagement state of the protruding piece and the engagement hole is shown, (A) is a sectional view, (B) is a plan view. Flow chart showing processing contents of control program The relative rotation state of a 1st rotation board and a 2nd rotation board is shown, (A) is sectional drawing at the time of engine normal rotation, (B) is sectional drawing at the time of engine reverse rotation

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 12 Crankshaft 14 1st rotation board 14A Slit 14B Projection piece 16 2nd rotation board 16A Slit 16B Engagement hole 18 Photoelectric sensor 18A Light projection element 18B Light reception element 20 Control unit

Claims (4)

At least one slit extending in the radial direction, and two rotating plates that are relatively rotatable and substantially parallel between the overlapping position and the non-overlapping position;
A sensor that is disposed opposite to the plate surfaces of the two rotating plates and outputs a signal according to whether or not the slit overlaps;
A rotation direction determining means for determining a rotation direction based on a signal from the sensor;
Comprising
Only one of the two rotating plates is fixed perpendicularly to the rotational axis of the rotational direction discrimination target, and the rotational direction discrimination device.   The two rotating plates are formed with a projecting piece projecting from one side to the other and an engagement hole with which the tip end of the projecting piece is engaged on the other side, so that the position between two positions is increased. The rotation direction discriminating apparatus according to claim 1, wherein the apparatus is configured to be relatively rotatable.   The rotation direction discriminating apparatus according to claim 1 or 2, wherein a plurality of the slits are formed at predetermined angles over the entire circumference of the two rotating plates.   The rotation direction determination device according to claim 1, wherein the sensor includes a photoelectric sensor including a light projecting element that emits light and a light receiving element that receives the light.

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