JPH0592625U - Displacement detector waterproof structure - Google Patents

Abstract

(57) [Abstract] [Purpose] A protective cover that protects the displacement detector that measures the amount of displacement of two relatively displaced members from the external environment is equipped with a drain plug that prevents water and dust from entering from the outside. Provided,
Water drops that enter the cover from the sealing surface are quickly discharged to the outside so that stable detection operation can always be obtained. [Structure] A through screw hole 1a is vertically provided at the lowest portion of the protective cover 1, and a recessed ring case 9 having a carry-out port 9a on its upper surface is sandwiched, and a lower end communicates with an outer periphery by a communication hole 10b. The threaded portion 10 having the hole 10a
A water drain plug 8 screwed from below is provided on a, and water that has entered the protective cover flows into the drain hole, and just pushes up the water level of the water accumulated in the water drain plug and flows out to the outside from the discharge port. To do.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a waterproof structure of a protective cover that protects a displacement detector from the external environment.

[0002]

[Prior Art]

 Conventionally, for example, an optical linear encoder used to detect the displacement of a moving shaft of a machine tool or the like has a scale 2 attached to a protective cover 1 fixed to one fixed body 6 of two members that relatively move as shown in FIG. The slider 3 is fixed and the slider 3 is attached to the other moving body 7, and the change in the amount of light caused by the relative movement between the scale 2 and the slider 3 is detected to detect the position data. Lip seals 5A and 5B that abut on both sides of the mounting handle 3a of the slider 3 to seal the inside of the protective cover are attached to the protective cover for a long time in the measuring direction. Prevents dust from entering.

[0003]

[Problems to be solved by the device]

 In the seal structure of the protective cover of the displacement detector described in the prior art, the lip seal abuts the mounting portion of the slider to keep the seal, so that the contact pressure is increased to improve the sealing performance. Since the measurement accuracy is adversely affected by the contact pressure, it is necessary to set the contact pressure to obtain the desired accuracy. For this reason, a perfect seal cannot be realized, and depending on the surrounding environment, water droplets may enter the cover, causing water droplets to accumulate in the protective cover, causing contamination of the optical system, and causing a malfunction in displacement detection. I had.

Further, as a method of solving this problem, there is a method of discharging water droplets accumulated in the protective cover through a discharge port provided with a filter. However, in this method, the filter is not waterproof and mist or the like may enter. There is a problem that the filter is clogged due to dust prevention and the drainage effect cannot be maintained. The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a waterproof structure of a displacement detector having a good waterproof effect and a draining effect of invading water drops. It is a thing.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, the waterproof structure of the displacement detector in the present invention is a waterproof structure of a protective cover that protects the displacement detector that measures the displacement amount of two relatively displaced members from the external environment. The drain hole for draining water and oil, etc. accumulated inside and the drain direction of this drain hole are bent, and the surface of the drain hole that contacts the external environment is covered and the outside of the drain hole at a position higher than the communication hole at the lower end of the drain hole. It is equipped with a water drain plug consisting of a cover opening to the environment and a screw hole for attaching this water drain plug to the protective cover.

[0006]

[Action]

 Since the slider of the displacement detector has to move in the measuring direction together with the moving body, the mounting handle protrudes from the opening of the protective cover, and the lip seal provided in the opening of the protective cover protects it from water and dust. ing. However, depending on the external environment, it is not possible to completely prevent water droplets from entering the protective cover from the seal surface. Due to its own weight, the invading water drops flow into the drain hole of the water drain plug provided in the lower part of the protective cover, push up the water level of the accumulated water in the water drain plug, and flow out to the outside from the outlet.

[0007]

【Example】

 An embodiment will be described with reference to FIGS. The protective cover 1 is fixed to the fixed body 6, and the scale 2 of the optical linear encoder is fixed in the protective cover 1. The scale 2 has a periodic lattice, and the slider 3 that reads and scans the scale of the scale 2 has a mounting handle 3a protruding from the opening of the protective cover and fixed to the moving body 7 so that the moving body is movable. The position changer is movable based on the change in the light amount caused by the relative movement between the slider 3 and the scale 2, and the position indicator is detected based on the change in the light amount.

Lip seals 5A and 5B are attached to the protective cover 1 in the measuring direction, and the lip seals 5A and 5B come into contact with both sides of the attachment handle 3a of the slider to protect water droplets and dust such as cutting fluid. It prevents the intrusion into the cover 1. The protective cover 1 is vertically provided with a penetrating screw hole 1a, and a drain plug 8 is attached to the screw hole 1a. The water drain plug 8 is composed of a screw portion 10 and a ring case 9. The screw portion 10 has a hole (drain hole) 10a at its center, which is a blind end, and the hole 10a has a lower end portion formed in a horizontal cross shape. It is opened to the outer periphery by the communication hole 10b.

The ring case 9 is a ring having a concave cross-section having discharge ports (notches) 9a at equal intervals on the circumference at the upper end, and the screw part 10 is fixed to the screw hole 1a so as to sandwich the ring case 9. ing. Therefore, the water flowing into the drain hole 10a flows out from the communication hole 10b, but is stored without being discharged to the outside until the water level in the ring case reaches the drain port 9a, and then flows into the drain hole 10a. As the water level rises, the water flows out through the outlet 9a. The path from the hole 10a to the discharge port 9a is bent so that external mist, water droplets, and dust do not enter the case. Further, a through screw hole 1b is also vertically formed in the upper portion of the protective cover 1, and a blind plug 12 is screwed into the screw hole 1b. The screw hole 1b is a preliminary hole for attaching the drain plug when the protective cover 1 is attached by 180 °.

Next, the operation of this embodiment will be described. The water droplets that have entered the protective cover 1 from the lip seal 5 flow to the bottom and flow into the drain hole 10 a of the drain plug 8. When water collects in the lower part of the drain hole 10a, the water level of this pool rises to the lower end position of the discharge port 9a at the same water level as the water collected in the recess of the ring case 9, and eventually the water that flows into the drain hole 10a rises to the water level. Each time it is pushed up, it flows out through the discharge port 9a. Therefore, water droplets or mist or dust that scatter outside will not enter from the outlet.

If water is collected from the beginning so as to block the communication hole 10b in order to prevent invasion from the outside, sufficient waterproofness can be obtained from the beginning. Further, although the drain hole 10a and the discharge port 9a are hardly clogged, even if it is clogged, the drainage plug 8 is simply removed from the screw hole 1a and replaced, and maintenance is very easy. Alternatively, the screw portion 10 and the ring case 9 may be integrated, and the water drain plug 8 may be formed as a single component. The waterproof structure of the present invention is not limited to the optical linear encoder of this embodiment, but can be applied to, for example, a magnetic encoder, an electrostatic encoder, a rotary encoder, or the like. Is.

[0012]

[Effect of the device]

 Since the present invention is configured as described above, it has the following effects. Water droplets that have entered the protective cover of the displacement detector are discharged to the outside through a drain plug located at a higher position than the communication hole at the lower end of the drain hole, so that a high waterproof effect is obtained. The water droplets can be reliably discharged to the outside, and stable detection operation can be maintained even in a bad environment.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a waterproof structure of a displacement detector of this embodiment.

FIG. 2 is an enlarged view of the water drain plug portion of FIG.

FIG. 3 is a configuration diagram of a waterproof structure of a conventional displacement detector.

[Explanation of symbols]

1 Protective cover 1a Screw hole 2 Scale 3 Slider 5A, 5B Lip seal 8 Drain plug 9 Ring case 9a Discharge port 10 Screw part 10b Communication hole

Claims (1)

[Scope of utility model registration request] 1. A waterproof structure of a protective cover that protects a displacement detector that measures the amount of displacement of two relatively displaced members from the external environment, and is a drainage for discharging water and oil accumulated inside. A drainage plug comprising a hole and a cover portion that bends the discharge direction of the hole and covers the surface of the hole that contacts the external environment and that is open to the external environment at a position higher than the communication hole at the lower end of the hole. A waterproof structure for a displacement detector, comprising a screw hole for attaching the drain plug to a protective cover.