JPH0623932Y2 - Linear encoder - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a linear encoder, and in particular, it is used around an engine of an automobile or is attached to a motor for MC,
The present invention relates to a linear encoder used for electrical control of an NC machine.

[Conventional technology]

In a conventional linear encoder of this type, as shown in FIG. 2, a part of the outer surface of a movable shaft 13 provided in a case 11 via a linear bearing 12 so as to be able to move in and out, in a circumferential direction, A magnetizing portion 15 composed of a magnetizing plate in which N poles and S poles are alternately arranged along the axial direction is provided, while a magnetic sensor 17 is provided on the inner surface of the case 11, and a magnetic sensor 17 is provided. Along with the movement in the axial direction, the magnetic sensor 17 detects the magnetizing signals of the N pole and the S pole of the magnetizing portion 15, whereby the movable shaft 1 relative to the case 11 is detected.
There are those that detect the position of No. 3.

[Problems to be solved by the device]

However, in such a conventional device, as the movable shaft 13 comes out of the case 11, the magnetized portion 15 provided on the outer surface of the movable shaft 13 passes through the linear bearing 12 and the case 11 moves. Exposed in the external atmosphere,
Therefore, the magnetized portion 15 is directly affected by the external atmosphere.

Further, in order to seal the inside of the case 11, for example, when a suitable seal member for sealing between the linear bearing 12 and the outer surface of the movable shaft 13 is provided in the portion of the linear bearing 12, the magnetizing part 15 is provided. When it passes through, it directly contacts the sealing member and deteriorates.

Further, in order to reduce such deterioration of the magnetized portion 15, if the sealing member is provided with an insufficient sealing function, for example, when used in an external atmosphere such as muddy water, muddy water in the external atmosphere may The magnetic sensor 17 and the magnetizing part 1 pass through the seal member and enter the case 11.
There was a problem that the gap with 5 was upset.

It is an object of the present invention to provide a linear encoder capable of solving the problems of the conventional ones described above, substantially eliminating the influence of the external atmosphere, and dramatically improving the reliability. It is a thing.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention provides a linear encoder in which a magnetic sensor provided in a case detects a magnetized portion provided in a movable shaft extending in and out from one end of the case along the axial direction thereof. , The movable shaft is formed in a tubular shape, the magnetized portion is arranged inside the tubular portion, and a fixed shaft that penetrates into the tubular portion from the other end is formed in the case. The magnetic sensor is arranged.

[Action]

By adopting the above-mentioned means in this invention, the magnetized portion is not exposed to the atmosphere outside the case, and the inside of the case can be sufficiently sealed without deteriorating the magnetized portion. Even when used in such an external atmosphere, muddy water in the external atmosphere is prevented from entering the case.

〔Example〕

 An embodiment of the present invention shown in the drawings will be described below.

FIG. 1 shows an embodiment of a linear encoder according to the present invention. In this linear encoder, a movable shaft 3 which is provided in a case 1 through a linear bearing 2 so as to be able to move in and out is cylindrical. And a magnetizing portion 5 composed of a magnetizing plate in which N poles and S poles are alternately arranged along the axial direction on a part of the inner surface of the tubular portion 4 in the circumferential direction. There is.

The case 1 is formed with a fixed shaft 6 that penetrates into the tubular portion 4 from the other end, and a magnetic sensor 7 is provided on the outer surface of the fixed shaft 6.

Next, the operation of the above will be described.

First, when the movable shaft 3 moves in the axial direction, the magnetic sensor 7
Detects the magnetization signals by the N pole and the S pole of the magnetized portion 5, and thereby detects the position of the movable shaft 3 with respect to the case 1.

At that time, even if the movable shaft 3 extends to the maximum extent from the case 1, the magnetized portion 5 arranged on the inner surface of the tubular portion 4 is not exposed to the outside atmosphere of the case 1 and is linear. There is no contact with the bearing 2.

Therefore, the magnetized portion 5 is not directly affected by the external atmosphere.

Further, in order to seal the inside of the case 1, for example, the linear bearing 2 and the movable shaft 3 are provided in the linear bearing 2 portion.
Even if an appropriate seal member for sealing the outer surface of the magnet is provided, the magnetized portion 5 does not directly contact the seal member and deteriorate.

As a result, since this sealing member can be used having a sufficient sealing function, even when used in an external atmosphere such as muddy water, muddy water in the external atmosphere passes through the sealing member and enters the inside of the case 1. Are substantially prevented.

Therefore, it always operates stably and properly.

[Effect of device]

According to the invention, as described above, in the linear encoder in which the magnetic sensor provided in the case detects the magnetized portion provided along the axial direction of the movable shaft coming in and out from one end of the case, The magnetized portion is formed in a tubular shape, the magnetized portion is disposed inside the tubular portion, and a fixed shaft that penetrates into the tubular portion from the other end is formed in the case, and the magnetic sensor is disposed on the fixed shaft. With such a configuration, it has an excellent effect that the influence of the external atmosphere can be substantially eliminated and the reliability can be dramatically improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of a linear encoder according to the present invention, and FIG. 2 is a sectional view of an essential part showing an example of a conventional encoder. 1, 11 ...... Case 2, 12 ...... Linear bearing 3,13 ...... Movable shaft 4 ...... Cylindrical part 5, 15 ...... Magnetic part 6 ...... Fixed shaft 7, 17 ...... Magnetic sensor

Claims (1)

[Scope of utility model registration request] 1. A linear encoder in which a magnetic sensor provided in a case detects a magnetized portion provided in a movable shaft extending in and out from one end of the case along an axial direction thereof, and the movable shaft is formed into a tubular shape. And forming the magnetized portion inside the tubular portion, forming a fixed shaft into the tubular portion from the other end of the case, and arranging the magnetic sensor on the fixed shaft. Characteristic linear encoder.