JPH04331370A - Rotational speed detector - Google Patents

Abstract

PURPOSE:To measure rotational speed of a body to be measured accurately by arranging a plurality of rotation detection sensors geometrically uniformly for a rotor rotating together with the body to be measured to determine a rotational speed by averaging outputs thereof. CONSTITUTION:For example, four rotation sensors if are arranged geometrically uniformly for a disc 13 rotating with a roller rotating shaft 3. The sensors 17 each has a light source 15 facing a photo detector 16 and receive light passing through a slit 14 provided on the disc 13. A detection signal is outputted to a cycle computation type tachometer 18, for instance and moreover, averaged with a mean computation circuit 19 to output a final rotational speed signal. According to this method, a rotational speed detected in parallel is averaged thereby achieving higher response and higher accuracy in the detection of the speed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting the rotational speed of a rotating object to be measured, such as a roller of a chassis dynamometer device.

0002

2. Description of the Related Art In order to detect the rotational speed of a rotating object to be measured, as shown in FIG. 3, conventionally, as shown in FIG. A plurality of slits 33 are provided at equal intervals around the entire circumference of this disc 32, and a light source 34 and a light sensor 3 are attached to the disc 32.
5 are arranged on both sides of the disc 32 so as to face each other, and a pulse signal generated by the movement of the slit 33 as the disc 32 rotates is converted into a rotational speed signal.

0003

[Problems to be Solved by the Invention] However, (1) it is difficult to provide the plurality of slits 33 in the disk 32 in the same shape and at equal intervals; (2) during assembly, the rotation axis 31 is located at the center of rotation of the disk 32; or pass the disc 32 through the rotating shaft 3.
Due to the difficulty of mounting the rotary shaft 31 perpendicularly to the rotary shaft 31, wow (low frequency fluctuation) occurs even when the rotating shaft 31 is constantly rotating.
In some cases, a rotational speed signal that appeared to be fluctuating was obtained. That is, as shown in FIG. 4, the rotational speed signal has different error times Δt1 and Δt
2, Δt3, and as a result, the detected rotational speed may include an error.

The present invention has been made with the above-mentioned considerations in mind, and its object is to provide an apparatus that can accurately measure the rotational speed of a rotating object to be measured.

[0005]

[Means for Solving the Problems] In order to achieve the above object, a rotation speed detection device according to the present invention has a plurality of rotation detection sensors arranged geometrically evenly on a rotating body that rotates together with an object to be measured. However, the rotational speed of the object to be measured is determined based on the average value of the outputs respectively obtained by these rotation detection sensors.

[0006]

[Operation] In the rotation speed detection device having the above configuration, a plurality of rotation detection sensors are geometrically evenly arranged on the rotating body that rotates together with the object to be measured, and the rotation speed signals from each rotation detection sensor are averaged. Since the rotational speed is calculated as the rotational speed, there is little variation in the detected value.In particular, since the rotational speed signals detected in parallel (simultaneously) are averaged, the responsiveness of speed detection is good.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, FIG. 2 schematically shows the configuration of a chassis dynamometer device to which a rotational speed detection device according to the present invention is applied. This is a roller (an example of an object to be measured) to be placed. Reference numeral 3 denotes a rotating shaft to which the roller 1 is attached so as to prevent slippage between the roller 1 and the roller 1, and is held horizontally by bearings 5 provided on the base 4 at appropriate intervals. 6 is a flywheel mechanically connected to one end of the rotating shaft 3 via a joint portion 7, and 8 is a bearing member.

Reference numeral 9 denotes a brake device provided on the other end side of the roller 1 for braking the roller 1, which is connected to a disc 10 attached to the roller 1 so as to rotate or stop integrally with the roller 1. It consists of a brake unit 11 that clamps a plate 10 and applies braking force to it. And 12
is a rotational speed detection device provided on the other end side of the roller 1 to detect the rotational speed of the roller 1, and an example of its configuration is shown in FIG.

In FIG. 1, reference numeral 13 denotes a disc (an example of a rotary body) attached to the rotary shaft 3 so as to rotate or stop integrally with the rotary shaft 3, and the entire periphery of this disc 13 has a plurality of Slits 14 are provided at equal intervals. In the vicinity of the disk 13, a plurality of rotation detection sensors 17 consisting of a light source 15 and a photodetector 16 are arranged geometrically evenly.
They are arranged point-symmetrically with the rotation axis 3 as the center.

That is, on one side of the disk 13 there are a plurality of (
In the illustrated example, four light sources 15 are arranged facing the slit 14 and point symmetrical, and on the other side, facing the light sources 15, the same number of light sources 15 are placed at positions that receive the light that has passed through the slit 14. A photodetector 16 is arranged. As the light source 15, for example, a light emitting diode, a tungsten lamp, etc. can be used, and the photodetector 1
As 6, a phototransistor, a photodiode, or the like can be used.

Reference numeral 18 denotes, for example, a periodic calculation type tachometer, which is provided on the output side of the four photodetectors 16, respectively.
Reference numeral 9 denotes an average value calculation circuit that arithmetic averages the outputs of the respective rotational speed meters 18.

In the chassis dynamometer device having the above configuration, a prescribed test is carried out by accelerating and rotating the roller 1 and the flywheel 6 by the driving wheels 2 of the test vehicle. By rotating together with the roller 1, rotational speed signals are output from each of the four tachometers 18, and these rotational speed signals are input to an average value calculation circuit 19, where they are arithmetic averaged, and from this average value calculation circuit 19, a final signal is output. A rotational speed signal is output, and by processing this as appropriate, the rotational speed of the roller 1 can be obtained.

According to the rotation speed detection device having the above configuration, four rotation detection sensors 17 are geometrically evenly arranged on the disk 13 that rotates together with the rotation shaft 3 of the roller 1, and each rotation detection sensor Since the rotation speed signals from 17 are averaged to obtain the rotation speed, there is little variation in the detected value.In particular, since the rotation speed signals detected in parallel (simultaneously) are averaged, the responsiveness of speed detection is good. . Therefore, the rotational speed of the rotating shaft 1 can be detected with high precision and responsiveness. It goes without saying that the number of rotation detection sensors 17 is not limited to the above four as long as they are arranged geometrically evenly with respect to the disk 13.

The present invention is not limited to the above-described embodiments, but may also include a method in which a plurality of gears are provided at equal intervals around a rotating body and the peaks of the gears are detected, or a magnet is placed on the surface of the rotating body. It can also be applied to a system in which they are provided at equal intervals and detected by a magnetic sensor.

[0016]

[Effects of the Invention] As explained above, according to the present invention,
The rotational speed of a rotating object to be measured can be detected with high accuracy and responsiveness without being affected by wow. The rotational speed detection device according to the present invention is particularly useful when examining changes in rotational speed.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing an example of a rotational speed detection device according to the present invention.

FIG. 2 is a diagram showing a main part of a chassis dynamometer device incorporating the rotational speed detection device.

FIG. 3 is a diagram showing a prior art.

FIG. 4 is a diagram for explaining the drawbacks of the prior art.

[Explanation of symbols]

3...Rotation shaft, 13...Disc, 17...Rotation detection sensor.

Claims (1)

[Claims] 1. A plurality of rotation detection sensors are arranged geometrically evenly on a rotating body that rotates together with the measured object, and the measured object is detected based on the average value of the output obtained by each of these rotation detection sensors. A rotational speed detection device characterized in that the rotational speed of a body is determined.