JPS58761A - Rotation speed sensor - Google Patents

Abstract

PURPOSE:To entirely remove an electromagnetic induction noise, and to make a titled device small-sized and light, by generating an optical pulse by an optical path provided at right angles with a shaft rotating in accordance with a car speed, and 2 optical fibers between which said path is placed, and detecting a rotation speed. CONSTITUTION:To a spindle 13 rotating in accordance with a car speed, a disk 17 provided with a permanent magnet 16 is fixed. On one side of a rotary shaft in an enclosed vessel 18, a turning plate 22 provided with N and S poles is provided, and on the other side, a groove 28 falling at right angles with the shaft 21 is provided. Optical fibers 23, 24 are placed by placing the groove 28 between them, and are connected to an electric power supply 25 and an optical signal processor 27. When the disk 17 is rotated in accordance with a car speed, the turning plate 22 is rotated through the magnet 16, a light beam from the optical fiber 23 passes through the groove 28, and is transferred to the fiber 24 as an optical pulse. In the processor 27, the optical pulse of a unit time is counted, the rotational frequency is detected, and the car speed is operated. In this way, since an optical fiber has been used as a signal transfer line, an electromagnetic induction noise is removed entirely, and also a device can be made small- sized and light-weight.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sensor that detects the rotational speed of a rotating body using an optical fiber, and is particularly suitable for application to a vehicle speed sensor of an automobile.

Currently, the signal transmission system of automobiles uses a method of transmitting electrical signals using a wire harness (a single electrical assembly), but as the electronics of automobiles have progressed in recent years, wire harnesses that cannot perform multiple transmission have become very expensive. This increases the weight of the vehicle, which has a negative impact on vehicle weight, fuel efficiency, etc.

This also applies to a vehicle speed sensor system that detects the speed of a vehicle and operates a vehicle speed meter, a USC device (electronically controlled skid control device), and even an automatic door lock mechanism based on the detected speed. This vehicle speed sensor is
Conventionally, the rotation of the differential is extracted from the transmission part and transmitted mechanically or electrically.

These signal transmission and detection means also have the above-mentioned weight reduction problem and electromagnetic induction noise problem, and improvements are desired as part of the transition to optical fiber signal transmission systems.

From this point of view, an object of the present invention is to provide a 1 m rotational speed detector using an optical fiber, which can be lightweight as a signal transmission system, and is free from problems such as electromagnetic induction noise.

The configuration of the rotation shorthand sensor of the present invention that achieves this object is such that a disk having a magnet fixed to its surface is attached to the rotating shaft of a rotary body, and the rotary body rotates a closed container facing the disk. The capillary is attached to a casing that is freely housed, and is provided in the closed container so as to be rotatable on an axis extending in the radial direction of the disk, and a magnet is fixed and rotates the thin tube intermittently when the magnet passes six times. A moving plate is attached to the shaft, while two optical fibers are placed opposite each other across the shaft, one of which is connected to a light source and the other is connected to an optical signal processing device that detects the rotational speed of the rotating body using light pulses. The tortoise is characterized in that an optical path tube is formed in a direction perpendicular to the axis for introducing the light beam projected from the one optical fiber into the other optical fiber.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a rotational speed sensor according to the present invention is applied to a vehicle speed sensor for an automobile will be described in detail below with reference to all the drawings showing the schematic structure thereof. Screw gear 1 that is created on the output shaft of a mission (not shown) and meshes with a nine-screw gear
A spindle 13 coaxially integrated with the rotating rod 12 is protruded from the other end of the rotating rod 12 on which 1 is carved in one direction.
This rotating rod 12 is fitted into a tension case 14 and rotatably supported by a nine casing 15 via a bearing (not shown). A disk 1f having a large number of permanent magnets 16 arranged in an annular shape is fixed to the spindle 13, and an airtight container 18 facing the disk 17 is fixed to the casing 15 via a set screw 19. There is.

In this embodiment, a large number of permanent magnets 16t may be arranged in a circular shape on the disk 17, and an annular permanent magnet may be fixed concentrically to the disk 17. -mm of a shaft 21 which is positioned in the radial direction of the circle [17 via a bearing 20 and is rotatably supported in a closed container 18] faces a permanent magnet 16, and is intermittently rotated by the passage of this permanent magnet 16. Main axis 21 [
Six rotating plates 22, which are made of rotating permanent magnets, are fixed and positioned so that the poles 1 and 8 of the plates face each other in a direction perpendicular to the shaft 21. Two optical fibers 23 and 24 are introduced into the sealed container 18, and the shaft 21t-
They are fixed so that they are sandwiched and facing each other. A light source 25 is connected to one optical fiber 21, and an optical signal processing device 27 is connected to the other optical fiber 24, which detects light pulses to speed up the passenger car and sends a mourning electric signal 4j to a speed display device 26. is connected.

Further, on the other end side of the shaft 21 where these optical fibers 23 and 24 face, a groove 28 is cut in a direction perpendicular to the shaft 21, allowing the light flux tube from one optical fiber 23 to be guided to the other optical fiber 24. However, the groove 28 as in this embodiment is used as an optical path.
In addition, it is also possible to use a through hole.

Therefore, if the polarities of the permanent magnets 16 are alternately changed and arranged on the disk 17, - permanent magnets 16 will be placed on the side of the rotating plate 22. 21 intermittently rotates in synchronization with the rotating body 12, and each time the optical fiber 23 rotates intermittently, the light beam from one optical fiber 23 becomes a light pulse and is transmitted from the other optical fiber 24 to the optical signal processing device 27.

For example, if four permanent magnets 16 are fixed to a disc, the shaft 21 will rotate twice in response to the rotation of the rotating body 1201, and four optical pulses will be transmitted to the optical signal processing device 27, so that the motor vehicle By determining the length of the wheel and the rotation ratio between the axle of this wheel and the rotating body 12, the optical signal processing device 27 counts the optical pulses per unit time and detects the rotation speed of the output shaft. , the corresponding vehicle speed can be fully automatically calculated and transmitted to the speed display device 26 as an electrical signal. Generally, optical fibers 23, 241-1 are assembled into a transmission and have a large amount of lubricating oil inside the casing 15.
If they are simply made to face each other within the casing 15, there is a risk that the KII4 lubricating oil on the opposing surfaces will intervene and make it impossible to accurately transmit all optical signals. Since the ends of the optical fibers 23 and 24 are introduced into the optical fibers 23 and 24, there is no adverse effect of atomized high-temperature lubricating oil, and it is possible to accurately introduce the optical pulse tube into the optical fibers 24.

Although Honjitsu IIA has applied the rotation speed sensor as a vehicle speed sensor, it can of course also be applied to electronic skid control devices (zBo) and automatic door lock devices, as well as various rotation detection sensors other than vehicle speed. It can also be used as Father, rotation 1 [22t - used as a light path,
It is also possible to transmit optical pulses from the other optical fiber 24 to the optical signal processing device 27 by making the pair of optical fibers 23 and 24 face each other with the rotary plate 22 in between. Further, in this embodiment, the shaft 211 is rotated only in one direction, so that the shaft 211 can be alternately swung by about 180 degrees.

As described above, according to the rotational speed sensor of the present invention, since an optical fiber is used as a signal transmission path, there is no influence of electromagnetic induction noise, and it is possible to achieve stable operation and to reduce the size and weight. In addition, since there are more non-contact parts than mechanical types, the load on the rotational drive system is less and the durability is excellent and it can be made into a 9-piece type.

[Brief explanation of the drawing]

The drawing shows a rotational speed sensor according to the present invention as a speedometer for a passenger car.
This is a principle diagram showing the simplified structure of an applied example. In the figure, l2 is a rotating body, l3 is a shaft, l5 is a casing, 16 is a permanent magnet, l7 is a disc, 18 Company sealed container, 2l is a shaft, =2#i rotating plate, 23 and 24 are optical fibers, 25 is a light source, and 27 is an optical signal processing device. Patent attorney Shiro Mitsuishi (and other names)

Claims (1)

[Claims] A disk having a magnet fixed on its surface is attached to the rotating shaft of a rotating body, and a sealed container facing the disk is attached to a casing in which the rotating body is rotatably housed, and the disk is rotated in the radial direction of the disk. A shaft extending from the shaft is rotatably provided in the closed container, and a magnet is fixed to rotate the shaft intermittently as the magnet passes through, and a round moving plate is attached to the shaft, while one end is connected to a light source. At the same time, two optical fibers C, the other of which is connected to an optical signal processing device that detects the rotational speed of the rotating body using an optical noculus, are placed opposite to each other with the axis in between, and furthermore, a beam is projected from one of the optical fibers. 2. A rotational speed sensor, characterized in that an optical path is formed on the axis in a direction perpendicular to the axis, for introducing the light beam into the other optical fiber.