JPH04306157A - Optical wheel speed sensor - Google Patents

Abstract

PURPOSE:To provide a wheel speed sensor which is capable of detecting wheel speed even under sever conditions such as an intense electromagnetic environment to which aircrafts are normally exposed or magnetically levitating vehicles and the like are exposed and a sandy environment, and which can be miniaturized and lightened. CONSTITUTION:An optical sensor 10 mounted on an alighting system axle has a simple structure having a rotary slit panel 11 having a required number of slits cut therein and the lens 14 of a light receiving and emitting portion disposed opposite and perpendicular to the surface of the panel 11, and the light receiving and emitting portion, a light source disposed inside a frame or a vehicle, and a light detection device 20 are connected to one another by an optical fiber cable 13.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to a wheel speed sensor used as a component of a brake control system for aircraft, magnetically levitated vehicles, etc., in which an optical sensor using a rotating slit plate is placed inside the landing gear axle. By connecting the light source and light detection device installed inside the vehicle with the wheels using optical fiber cables, it is possible to accurately detect wheel speeds even in the strong electromagnetic environment to which magnetically levitated vehicles are normally exposed. This invention relates to an optical wheel speed sensor that is smaller and lighter.

0002

[Prior Art] Conventionally, wheel speed sensors, which are indispensable as components of brake control systems for aircraft, etc., are shown in Figs. 2 and 3.
As shown in the figure, the stator 1 and the rotor 3 have teeth cut into them, and a direct current flows through the coil 4, so that when the rotor 3, which is mounted inside the landing gear axle and is driven by the rotating shaft 2, rotates, Generally, a method is adopted in which speed is detected by using a sinusoidal electromotive force whose magnetic resistance changes as the wheel rotates, and which generates a sinusoidal electromotive force having a frequency proportional to the number of rotations of the wheel.

0003

[Problems to be Solved by the Invention] With this magnetic method, due to the limitations of machining that involves cutting gears into the stator and rotor, the resolution, that is, the number of sine waves per revolution, can be mounted on an axle with an inner diameter of 40 mm. In the case of sensors, the limit is about 150 ppr, and the peak voltage decreases as the rotation speed decreases, making it difficult to accurately detect speed in low speed regions and hindering brake control. .

[0004] Furthermore, since the output signal from this magnetic sensor installed in the landing gear axle is transmitted as an electrical signal to the control electronic box, the signal is disturbed in the electromagnetic environment to which aircraft etc. are normally exposed. This is possible, and confirmation through special measures or tests is essential. Magnetic sensors utilize the electromagnetic principle, so
The components require the use of magnetic materials, coils, etc., which is an obstacle to reducing the weight of the device.

Furthermore, conventional magnetic sensors cannot be used in vehicles that utilize the principles of magnetic levitation and magnetic propulsion.

Furthermore, in some conventional propeller aircraft, steering control during ground taxiing is mainly performed by propeller pitch control including propeller reversing. If this propeller pitch control method is used under severe conditions such as a dusty environment, there is an increased possibility that the engine will inhale dust, etc. kicked up by the reverse thrust of the propeller, which may cause failure of these devices.

The present invention solves the above-mentioned problems of the conventional magnetic sensors in wheel speed sensors for aircraft, magnetically levitated vehicles, etc., and uses strong electromagnetic environments and dusty environments to which magnetically levitated vehicles are normally exposed. The object of the present invention is to provide a wheel speed sensor that can accurately detect wheel speeds even under severe conditions, and that can be made smaller and lighter.

[0008]

[Means for Solving the Problems] This invention provides a method for rotatably supporting a rotary slit plate in which a required number of slits are cut on a mirror-polished thin plate surface, and for optically detecting the number of rotations of the slit plate. A rotating slit plate is mounted in the landing gear axle of the aircraft or vehicle so that the rotary slit plate can be driven by the rotation of the wheels, and the light receiving and emitting parts are arranged opposite to each other in the direction perpendicular to the plane of the plate. This is an optical wheel speed sensor characterized by connecting a light source and a light detection device arranged in a vehicle with an optical fiber cable.

The present invention also provides an optical wheel speed sensor according to claim 1, characterized in that an optical fiber cable disposed between the landing gear axle and the aircraft body or vehicle is covered with a metal flexible tube. be.

0010

[Operation] The present invention provides a light sensor mounted on the landing gear axle with a simple structure consisting of only a rotary slit plate with a required number of slits cut therein and a light receiving/emitting unit disposed opposite to the plate in a direction perpendicular to the plate. By using an optical fiber cable to connect the light emitting unit, the light source located inside the aircraft or vehicle, and the light detection device, the speed sensor attached to the landing gear axle can be made smaller and lighter, and the distance from the sensor to the light detection device can be reduced. Since the signal transmission between the two is performed using optical signals, the photodetector can be placed inside an aircraft or vehicle where electromagnetic environmental conditions are mild, and accurate speed detection is possible even under electromagnetic environmental conditions.

[0011] Furthermore, since the present invention uses a rotating slit plate for the optical sensor, it is relatively easy to increase the number of pulses by increasing the number of slits in the rotating slit plate per one rotation of the wheel. Inner diameter is 40
For a sensor that can be installed on a mm axle, 1200
The number of pulses on the order of ppr can be easily obtained.

In the present invention, the wheel speed can be detected by optically counting the light pulses obtained by the rotation of the rotary slit plate, and then detecting the wheel speed by a known electrical calculation process using a light source and a light detection device. , the computing device can be used in any configuration.

When the wheel speed sensor according to the present invention is applied to an aircraft, it is necessary to install it inside the axle of the landing gear, and since the landing gear often has a buffer mechanism, the signal output from the optical sensor is It is necessary to install the device along the outside of the aircraft or vehicle where there is a high possibility of collision with external obstacles, such as by crawling over the device itself. Therefore, the optical fiber cable is covered with a flexible metal tube made of stainless steel or the like. This ensures strength against collisions with external obstacles, prevents interference with signal transmission, improves the handling of the optical fiber cable, and easily prevents damage to the optical fiber when it is attached to or removed from the aircraft or vehicle. Can be done.

[0014]

[Embodiment] A sensor housing 10 installed inside the axle of an aircraft landing gear has a rotary slit plate 11, which is a mirror-polished thin plate with 300 slits cut on its circumferential surface, and is rotatably driven by the rotation of a tire. A lens 14 is fixed to a rotating shaft 12 and connected to an optical fiber cable 13, and serves as a light receiving and emitting part for the rotating slit plate 11. A lens 14 is disposed on the rotating slit plate 11 so as to face the plate surface in a direction perpendicular to the plate surface.

The light source/detection device 20 disposed inside the aircraft is connected to the sensor housing 10 by the optical fiber cable 13 as described above, and has the functions of emitting light and detecting light. 22, the light passes through half mirrors 23, 23, and is output from lenses 24, 24 to optical fiber cables 13, 13. In the figure, reference numerals 25 and 25 indicate power supply boards for the light source.

Furthermore, the optical signal emitted from the lens 14, reflected by the rotating slit plate 11, and returned through the optical fiber cable 13 is separated by half mirrors 23, 23, converted into electrical signals by light receiving elements 26, 26, and then sent to an amplifier. board 27,
At step 27, the signal is amplified and shaped into a pulse signal, and is outputted to the brake control electronic box 40 through the gain adjuster 30.

[0017]

[Effects of the Invention] The wheel speed sensor according to the present invention can be used in a strong electromagnetic environment such as a magnetically levitated vehicle.
By increasing the number of slits in the rotating slit plate, it is possible to avoid an increase in the number of pulses and a drop in the output voltage peak value during low speed rotation, enabling accurate speed detection in the low speed range and achieving precise brake control. can. Additionally, since it is an optical sensor, it does not use magnetic materials, making it possible to make the device smaller and lighter.

The wheel speed sensor according to the present invention can be used in aircraft and vehicles that utilize the principles of magnetic levitation and magnetic propulsion, and can also be used in propeller aircraft that are frequently used in dusty environments, such as propeller reversing during ground taxiing. By using it on aircraft that perform steering control using propeller pitch control including propeller pitch control, it is possible to accurately detect speed in the low speed region and achieve precise brake control. Failure of equipment such as engines can be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating an example of a wheel speed sensor according to the present invention.

FIG. 2 is a longitudinal cross-sectional view showing the configuration of a conventional wheel speed sensor.

FIG. 3 is a longitudinal cross-sectional explanatory diagram of a conventional wheel speed sensor taken along line A-A in FIG. 2;

[Explanation of symbols]

1 Stator 2 Rotation axis 3 Rotor 4 Coil 10 Sensor housing 11 Rotating slit plate 12 Rotation axis 13. Optical fiber cable 14 Lens 20 Light source-detection device 21 Light source 22 Lens 23 Half mirror 24 Lens 25 Power supply board for light source 26 Photo receiving element 27 Amplifier board 30 Gain adjuster 40 Brake control electronic box

Claims (2)

[Claims] Claim 1: A rotating slit plate with a required number of slits cut into a mirror-polished thin plate surface is rotatably supported, and a light receiving and emitting section for optically detecting the rotational speed of the slit plate is mounted on the same plate surface. A rotary slit plate is installed in the landing gear axle of the aircraft or vehicle so that it can be driven by the rotation of the wheels, and the optical sensor is arranged opposite to each other in the orthogonal direction of An optical wheel speed sensor characterized by connecting detection devices with an optical fiber cable. 2. The optical wheel speed sensor according to claim 1, wherein an optical fiber cable disposed between the landing gear axle and the aircraft body or vehicle is covered with a flexible metal tube.