JPH0544732Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an encoder that detects the rotation angle or rotation speed of a motor rotation shaft.

[Conventional technology]

A direct drive motor is equipped with an encoder to accurately detect the rotation angle or rotation speed of the rotary shaft that serves as the output shaft. This encoder generally has a structure in which a rotating disk is attached to a shaft attached to the rotating shaft of a motor, and the rotation of the rotating disk is detected optically or magnetically to determine the position of the rotating shaft. on the other hand,
In direct drive motors, the rotation of the rotary axis directly affects the machining accuracy and the operating accuracy of the equipment, so the encoder that positions the rotary axis requires high resolution and precision, and is capable of generating 100,000 to 1 million pulses/
The number of rotational positioning pulses is required. Therefore, for example, in an optical encoder, the number of optical slits formed on the rotating disk is tens of thousands (at least about 30,000), and the optical signal passing through the slits is electrically multiplied to satisfy the above requirements. There is.

However, in order to form tens of thousands of slits, there are limits to the accuracy of the slitting machine and etching accuracy, and the outer diameter of the rotary disk becomes large due to the diffraction phenomenon of transmitted light. By the way,
For a slit width of 4 μm, the rotating disk is 100
Requires a diameter of ~200mm. As the diameter of the rotary disk increases, the weight of the rotary disk increases, placing a burden on the motor output. For this reason, attempts have been made to reduce the weight of the encoder by molding the entire constituent parts of the encoder, including the rotary disk, from lightweight non-metallic materials such as ceramics and plastics.

[Problem that the invention attempts to solve]

However, when the encoder components are made of non-metallic lightweight materials, it is not possible to reliably block out noise such as external radio waves, which not only causes errors in detection accuracy, but also causes the following problems depending on the material of the lightweight materials: It has the following problems.

In the case of ceramic Ceramic has a specific gravity of 3 to 4, making it easier to reduce weight compared to iron, stainless steel, etc. (7.8 to 7.9), but it is difficult to cut the surface of ceramic with high precision, and , it takes a long time to process, is expensive, and is not practical.

In the case of plastic, it is possible to reduce the weight like ceramics, but it is difficult to process with high precision because dimensional errors occur due to expansion and contraction due to temperature changes (especially during molding) and changes over time. On the other hand, we use plastic mixed with glass fiber to improve dimensional accuracy.
Although this plastic has been annealed, the dimensional accuracy still changes over time because the orientation of the glass fibers changes during surface machining.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide an encoder that is lightweight, inexpensive, has good dimensional accuracy, and is less affected by external noise.

[Means for solving problems]

To achieve the above object, the present invention provides a rotating disk that is attached to a shaft that is attached to a rotating shaft and rotates integrally with the rotating shaft, and a housing that rotatably supports the shaft and has a cover that surrounds the rotating disk. and a sensor provided in a housing corresponding to the rotary disk to optically or magnetically detect the rotation of the rotary disk to detect the rotation angle or rotation speed of the rotary shaft. The shaft and the housing are made of a non-metallic lightweight material, and a mounting plate made of a thin metal plate is provided on at least the sensor fixing surface of the housing and the rotary disk fixing surface of the shaft.

[Effect]

Since the present invention is constructed as described above, weight reduction is facilitated by the use of lightweight non-metallic materials, and improvement in accuracy and strength of parts requiring dimensional accuracy is achieved by the use of mounting plates.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to illustrative embodiments. In each embodiment, the same elements are denoted by the same reference numerals, and redundant explanation thereof will be omitted.

FIG. 1 is a vertical sectional view of the upper half of an embodiment of the present invention. This embodiment is an example applied to a direct drive motor, and moreover, an example using an optical encoder. Motor rotation axis (not shown)
The hollow shaft 1 is adapted to rotate integrally with a rotating shaft attached to the shaft 1. Shaft 1
By making the shaft 1 hollow, the weight of the shaft 1 is reduced. The shaft 1 is rotatably supported by a housing 3 via a bearing 2, and a rotary disk 7 is attached in the axial direction of the shaft 1. A large number of slits (not shown) are formed in the rotary disk, and it rotates integrally with the shaft 1, that is, the rotation axis of the motor, and its rotation angle or rotation speed is detected by an optical sensor described later. It's becoming like that. Therefore, optical sensors are arranged around the rotary disk 7 so as to correspond to the slits of the rotary disk 7. In this embodiment, the optical sensor is installed in a case 8 provided on the left side of the rotary disk 7.
A light emitting element 9 such as an LED, a fixed slit plate 6 provided on the right side of the rotating disk 7, and a light receiving element such as a photodiode (not shown) that supports the fixed slit plate 6 and receives light emitted from the light emitting element. The sensor base 5 is attached and fixed to the housing 3, and is further provided with a waveform processing circuit 10 for waveform processing the signal detected by the light receiving element. In such a configuration, the light from the light emitting element 9 passes through the slit of the rotating disk 7 and the slit of the fixed slit plate 6, and is received by the light receiving element as an optical signal, thereby causing the rotation of the rotating disk 7, that is, the rotation axis of the motor. The rotation angle or rotation speed is adapted to be detected.
Further, in order to isolate such an optical sensor from the outside world and ensure its detection operation, the housing 3 is provided with a cover portion 12 that surrounds the entire optical sensor.

Here, the shaft 1 is formed with a hub portion 1a that projects in the radial direction, and the rotary disk 7 is fixed to this hub portion 1a.

In this configuration, the housing 3 and the shaft 1 do not require much dimensional accuracy, and non-metal lightweight materials such as ceramic or plastic are used for these parts, thereby reducing the weight of the entire encoder. On the other hand, the rotary disk 7 needs to be assembled with high precision because the slit requires high resolution. This serves in particular as a fixing surface for the rotary disk 7. It is necessary to make the shaft 1 perpendicular to the hub portion 1a with high accuracy, and for this reason, the hub portion 1a is provided with a mounting plate 1 made of a thin metal plate.
1 is glued, and the rotary disk 7 is fixed via this mounting plate 11. This improves the mounting accuracy of the rotary disk 7, thereby preventing its wobbling and making it possible to detect the slit with high precision. Further, the fixed slit plate 6 is required to have parallelism with the slit of the rotary disk 7 and dimensional accuracy of the gap with the slit of the rotary disk.
Therefore, the sensor base 5 supporting the fixed slit plate 6 is fixed to the housing 3 via the mounting plate 4 made of a thin metal plate, and its dimensional accuracy is maintained. The mounting plate 11, which is made of a thin metal plate with high strength, is used for parts that require dimensional accuracy in this way.
4 maintains dimensional accuracy in microns, other parts including the shaft 1, housing 3, rotary disk 7, and fixed slit plate 6 can be molded from non-metallic lightweight materials, and the entire encoder It is possible to satisfy the conflicting demands of weight reduction and improvement of partial mounting accuracy. In this embodiment, the cover portion 12 surrounding the sensor constitutes a shield plate made entirely of a thin metal plate. The end of this shield plate on the side of the housing 3 is connected to the mounting plate 4, so that the entire sensor is covered with a metal plate. Therefore, since external noise can be blocked very effectively, there is an advantage that the detection accuracy of the sensor is improved.

FIG. 2 shows a modification of the connection between the shield plate and the mounting plate 4, in which the shield plate is fitted onto the outer end surface of the mounting plate 4. As a result, the mounting plate 4 has a structure that also serves as a spigot, so that the spigot portion can be machined when machining the mounting plate 4, and a higher degree of mounting accuracy can be achieved.

FIG. 3 shows another embodiment of the present invention, in which a magnetic sensor is used as the sensor. In this embodiment, a magnetic disk is used as the rotating disk 7, and a magnetoresistive element 1 is placed on the circumferential side of the magnetic disk.
3 are arranged. The magnetoresistive element 13 is attached to the sensor base 5 and extends in the axial direction of the shaft 1, and a mounting plate 4 made of a thin metal plate is disposed on the housing 3, which serves as a fixed portion of the sensor base 5. Further, a mounting plate 11 made of a thin metal plate is similarly provided on the hub portion 1a of the shaft 1, which serves as a fixing surface for the magnetic disk, thereby maintaining dimensional accuracy. Further, the cover portion 12 surrounding the magnetic sensor is also formed of a shield plate made of a thin metal plate to block external noise. Therefore, similarly to the embodiments described above, it is possible to reduce the weight of the encoder and improve mounting accuracy.

FIG. 4 shows yet another embodiment of the invention. Sleeves 15 and 16 made of thin metal plates are provided on the upper and lower surfaces of a bearing 2 that rotatably supports the shaft 1. The sleeve 15 is bonded to the lower surface of the housing 3, while the sleeve 16 is bonded to the upper surface of the shaft 1. Since the inner race and outer race of the bearing 2 are supported with high precision by these sleeves 15 and 16, the shaft 1 can be attached to the housing 3 with precision in microns. In the figure, 17 and 18 are nuts for fixing the bearing 2, and the sleeve 1
5 and 16 are also extended to this part. Therefore, the extension portions of the sleeves 15, 16 are threaded to engage the nuts, but the sleeves 15, 16 are
Since it is made of a thin metal plate, the nut can be screwed securely, and the mounting strength during screwing is also improved.

Note that the present invention is not limited to the above embodiments, and can be modified in various ways. In order to improve the detection accuracy of the sensor, this invention uses a thin metal plate as the fixing surface for parts that require high dimensional accuracy. Some thin metal plates may be omitted. or,
In the cover part 12, since the thin metal plate blocks external noise, the entire cover part 12 does not need to be made of a thin metal plate, and only the surface of the cover part 12 may be covered with a thin metal plate. Furthermore, the cover part 12
A magnetic metal plate can be used to provide magnetic shielding.

[Effect of idea]

As described above, the present invention uses thin metal plates for parts that require dimensional accuracy, such as the fixed surface of the rotating disk and the fixed surface of the sensor base that supports the fixed slit plate that is the component of the sensor. In addition to eliminating the need for high-precision processing,
Parts that do not require dimensional accuracy can be molded from lightweight non-metallic materials, making it possible to reduce the weight of the encoder.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of the upper half of an embodiment of the present invention, Fig. 2 is a partial sectional view showing a modification thereof, and Fig. 3 is a partial sectional view of the upper half of an embodiment of the present invention.
The figure is a longitudinal sectional view of another embodiment, and FIG. 4 is a longitudinal sectional view of still another embodiment. DESCRIPTION OF SYMBOLS 1... Shaft, 1a... Hub part, 2... Bearing, 3... Housing, 4, 11... Mounting plate, 5... Sensor base (sensor), 6... Fixed slit plate (sensor), 7... ...Rotating disk, 8
...LED case, 9 ...Light emitting element (sensor), 1
0... Waveform shaping circuit (sensor), 12... Cover part, 13... Magnetoresistive element (sensor), 15, 1
6...Sleeve, 17, 18...Natsuto.

Claims (1)

[Claims for Utility Model Registration] 1. A rotating disk that is attached to a shaft that is attached to a rotating shaft and rotates integrally with the rotating shaft, and a housing that has a cover that surrounds the rotating disk and rotatably supports the shaft. , a sensor provided in a housing corresponding to the rotating disk and detecting the rotation of the rotating disk optically or magnetically to detect the rotation angle or rotation speed of the rotating shaft. and a housing made of a non-metallic lightweight material, a mounting plate made of a thin metal plate is provided on at least a sensor fixing surface of the housing and a rotary disk fixing surface of the shaft, and the cover part is electrically connected to the mounting plate. An encoder characterized by comprising a thin-walled metal plate. 2. The encoder according to claim 1, wherein the shaft support portion of the housing is provided with a sleeve made of a thin metal plate.