JPS6022667A - Rotation number sensor - Google Patents

Abstract

PURPOSE:To obtain an inexpensive optical sensor of the number of revolutions superior in durability by arranging a thermally stable heat resisting light emitting element near an encoder to prevent the influence of an environmental temperature. CONSTITUTION:A heat resisting light emitting element, for example, an incandescent lamp 4 and a tip part 5a of an optical fiber 5 which receives the light from the lamp are arranged to face the position of a narrow hole 3 of an encoder 1 attached to a revolving shaft 2 which drives a body to be rotated. The detection signal from a photodetector 6 is processed in a detecting circuit part 7 constituted on a printed board to output a signal of the number of revolutions. When the encoder is connected directly to the driving shaft of a wheel, characteristics are not changed in distinction from the use of a semiconductor element such as an LED and a stable operation is kept for a long time though the temperature rises considerably during running.

Description

[Detailed description of the invention] The present invention relates to an optical rotation speed sensor.

In recent years, as automobiles have become more highly electrically equipped, it has become possible to collect all information related to automobile driving control and perform arithmetic processing on this information to control the operation of automobiles. For this reason, various measuring devices that collect more sophisticated information regarding the driving conditions of automobiles and control devices that control driving based on this information have been developed. As one such measuring device, a rotation speed sensor that measures the rotation speed of an automobile engine or wheels has been developed. Currently, there are optical rotation speed sensors in encoders that use a pair of optical fibers placed opposite to each other in a narrow gap, but these sensors are expensive and leave room for improvement.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical word-of-mouth number sensor that has a simple structure, is inexpensive in terms of cost, and has excellent durability.

The configuration of the rotation speed sensor according to the present invention that achieves the above object includes an encoder in which a plurality of pores are arranged at equal intervals around a disk driven by the rotation of a rotating body to be measured, and a plurality of pores in the encoder. A heat-resistant light-emitting element arranged to face each other, an optical fiber having a tip end portion of an optical fiber that receives light from the heat-resistant light-emitting element, and a light-receiving element optically coupled to the base of the optical fiber. Then, the detection output of the light receiving element was processed to be proportional to the rotational speed of the rotating body to be measured. It is characterized by comprising a detection circuit unit that outputs a signal.

A rotation speed sensor according to the present invention will be explained with reference to the drawings of one embodiment. The figure is a perspective view showing the structure of the rotation speed sensor according to the present invention.

In the figure, an encoder l that generates information proportional to the number of rotations is a disk attached to a rotating shaft 2 that drives a rotated object, and is arranged at equal intervals along the circumference of the encoder disk. There are n pores 3. encoder l
A heat-resistant light emitting element such as an incandescent lamp 4 and a distal end portion 5a of an optical fiber 5 that receives light from the incandescent lamp through the pore 3 of an encoder are arranged opposite to the pore 3 of the encoder. Therefore, with one rotation of the encoder, the optical fiber 5 Fi,
Observe n light pulses.

Furthermore, the rotational speed can be detected with one revolution of the encoder. A light receiving element 6 optically coupled to the optical fiber 5 is arranged at the base of the optical fiber 5 . Further, the light receiving element 6 inputs a detection signal to a detection circuit section 7 configured on a printed circuit board. The detection circuit section 7 processes the detection signal and outputs a rotation speed signal converted into the rotation speed of the rotating body.

This rotational speed signal can be used to display the rotational speed in the form of numbers or bar graphs on a display device.

Therefore, if it is the rotation speed of a wheel, it can be immediately converted to vehicle speed and displayed.If the encoder of the rotation speed sensor, which is the vehicle speed sensor, is directly connected to the drive shaft of the wheel, the drive @ surrounding area is The environment around the encoder, which is housed in a sealed case, is in a thermally harsh environment, and the characteristics of semiconductor devices such as LEDs change, making it difficult to maintain stability over a long period of time. No action is expected. Some conventional structures have two optical fibers facing each other with an encoder sandwiched between them, but sensitivity is sensitively affected by optical axis misalignment of the optical fibers, and the optical fibers themselves are expensive and cost-effective. It was inevitable that it would rise. However, the rotation speed sensor of the present invention has a heat-resistant light emitting element, such as an incandescent lamp, that is thermally stable in such an environment, and is not affected by the temperature of the environment. It also has the advantage of being easy to optically couple with the optical fiber 5. Furthermore, since the optical fiber 5 transmits the received light signal between the light receiving element 6 and the light receiving end, it is not affected by external noise. In addition, compared to conventional optical fibers that use optical fibers as transmitting/receiving lines, it is much cheaper in terms of price because it does not use all optical fibers for transmitting light9, and there is no need to adjust the optical coupling between optical fibers. It is robust and durable.

In the embodiments of the present invention, all incandescent lamps were used for the heat-resistant light emitting elements, but the invention is not limited to this, and as long as the optical fiber transmits infrared rays with low loss, a crosstalk generator such as a heating wire may also be used. good.

[Brief explanation of the drawing]

The figure is a perspective view of a rotational speed sensor according to the invention. In the figure, 1 is an encoder, 2 is a rotating shaft, 3 is a pore, 4 is a heat-resistant light emitting element, 5 is an optical fiber, 6 is a light receiving element, and 7 is a detection circuit section. Patent applicant: Sumitomo 'I Niki Kogyo Co., Ltd. Agent: Patent attorney: Shibu Mitsuishi (and one other person)

Claims (1)

[Claims] an encoder having a plurality of pores arranged at equal intervals around a disk driven by the rotation of a rotating body to be measured; a heat-resistant light emitting element disposed opposite to each other with respect to the pores of the encoder;
an optical fiber having a tip that receives light from the heat-resistant light-emitting element; a light-receiving element optically coupled to the base of the optical fiber; and a detection output of the light-receiving element being processed to detect the rotation to be measured. A rotation speed sensor comprising a detection circuit section that obtains a signal proportional to the rotation speed of a body.