JP2008089159A - Gear unit sealing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear unit sealing structure free from sealing impair even when sudden impact is applied thereto, without the need for greatly changing its shape. <P>SOLUTION: The gear unit sealing structure comprises a body consisting of a bottomed box having an opening portion formed at the upper part by a wall portion covering the periphery, and a cover covering the opening portion, the body incorporating a gear. A joint part between the box and the cover consists of a wall end portion as the upper end of the wall portion, a cover joint portion opposed to the wall end portion, and liquid gasket laid between the wall end portion and the joint portion. The seal width of the liquid gasket is set greater by at least a predetermined shift between the box and the cover than the width of the wall end portion. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a gear unit seal structure, and more particularly to a gear unit seal structure using a liquid gasket.

2. Description of the Related Art Conventionally, a gear unit that manually drives a valve such as a butterfly unit has a main body constituted of a box that houses a gear and a cover that is fixed to the box via a bolt. A seal structure that can prevent the lubricating oil filled in the box from flowing out and the entry of water and the like from the outside is used at the joint between the box and the cover.
As this seal structure, there are a structure in which a soft plate-like gasket is disposed at a joint portion between a box and a cover, a structure in which an O-ring is disposed (for example, see Patent Document 1). In recent years, in order to reduce the number of parts and reduce costs, a structure in which a liquid gasket is applied to the joint between the box and the cover has been developed.
JP-A-9-203465

  By the way, when a valve equipped with a gear unit is transported or piped, a sudden impact or excessive load may be applied to the gear unit, and the cover may be displaced from the box. If the seal structure uses a liquid gasket at the joint between these boxes and the cover, the liquid gasket is cured into a thin film to ensure a sealing property. And peeling may occur, and the sealing performance may be impaired.

  In order to prevent such a deterioration of the sealing performance, a measure is conceived that increases the fastening force of the bolts and suppresses the displacement of the cover. However, in order to withstand the fastening force of this bolt, the thickness of the box and cover is increased, the nominal diameter of the bolt is increased, and the external dimensions of the box and cover are increased with these changes, etc. It is necessary to make a significant shape change. As described above, an increase in the fastening force of the bolt causes an increase in cost and an increase in the weight of the gear unit.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and obtains a gear unit seal structure that does not impair the sealing performance even when sudden impact or the like is applied, without a significant shape change. For the purpose.

The invention described in claim 1
In a seal structure of a gear unit that has a bottomed box in which an opening is formed at the top by a wall covering the periphery and a cover that covers the opening, and a gear is built in the body.
The joint portion between the box and the cover is interposed between a wall end portion which is an upper end portion of the wall portion, a joint portion of the cover facing the wall end portion, and the wall end portion and the joint portion. The liquid gasket
The seal width of the liquid gasket is set to be wider than the width of the wall end by at least a predetermined shift amount between the box and the cover.

  According to the first aspect of the present invention, since the seal width of the liquid gasket is set to be wider than the width of the wall end by at least a predetermined shift amount between the box and the cover, A protruding portion is formed. As a result, even if a sudden impact or excessive load is applied and the box and cover are displaced and the liquid gasket is cut or peeled off, the portion of the liquid gasket that protrudes from the wall edge is the sealing property between the box and the cover. Will be secured. Since only the seal width of the liquid gasket needs to be made wider than the width of the wall end by at least a predetermined amount of deviation between the box and the cover, the sealing performance is ensured without having to change the shape of the gear unit itself. It becomes possible to do.

The invention according to claim 2 is the seal structure of the gear unit according to claim 1,
A notch is provided in at least one of the wall end of the box or the cover joint;
By filling the liquid gasket inside the notch, a thicker part than the liquid gasket located outside the notch is formed.

  According to the second aspect of the present invention, since a part of the liquid gasket is a thick part, it is less likely to be damaged as compared with a thin film as a whole, resulting in an increase in sealing performance. become.

The invention according to claim 3 is the seal structure of the gear unit according to claim 2,
The corner portion of the notch covered with the liquid gasket is formed in an arc shape.

  Here, if the cover is displaced after the box and the cover are fastened, stress concentration occurs in the liquid gasket due to the corners of the notch, and the liquid gasket may be damaged and the thin film portion of the gasket may be peeled off. However, since the corners of the notches covered with the liquid gasket are formed in an arc shape as in the invention described in claim 3, the stress concentration on the liquid gasket can be dispersed and the liquid gasket is prevented from being damaged. can do.

  According to the present invention, even if a sudden impact or excessive load is applied and the box and the cover are displaced and the liquid gasket is cut or peeled off, the portion of the liquid gasket that protrudes from the wall end is separated from the box. Sealing performance with the cover will be ensured. Since only the seal width of the liquid gasket needs to be made wider than the width of the wall end by at least a predetermined amount of deviation between the box and the cover, the sealing performance is ensured without having to change the shape of the gear unit itself. It becomes possible to do.

  The gear unit seal structure according to the present invention will be described below. First, the gear unit will be described. FIG. 1 is a side sectional view showing a schematic configuration of the gear unit. As shown in FIG. 1, the gear unit 1 includes a box 4 containing a worm 2 and a worm wheel 3, a cover 5 that covers the worm 2 and worm wheel 3 in the box 4 and serves as a lid of the box 4, and a box 4 and a bolt 9 for fastening the cover 5 are provided. That is, the gear unit 1 has a main body constituted by the box 4 and the cover 5, and gears such as the worm 2 and the worm wheel 3 are built in the main body.

  FIG. 2 is a top view showing the internal structure of the box 4 before the cover 5 is attached. As shown in FIGS. 1 and 2, the box 4 is formed in a bottomed shape with an opening O formed at the top by a wall portion 6 that covers the periphery, and a worm storage for storing the worm 2 therein. A portion 41 and a wheel storage portion 42 for storing the worm wheel 3 meshed with the worm 2 are provided. The upper end portion (wall end portion 61) of the wall portion 6 of the box 4 is joined to the cover 5. Hereinafter, a portion of the cover 5 that is joined to the wall end 61 of the box 4 is referred to as a joint 7 (see FIG. 1).

As shown in FIG. 2, a pair of bearings 43 that rotatably support the worm shaft 21 of the worm 2 are disposed in the worm storage portion 41. A handle (not shown) is connected to the end of the worm shaft 21, and when this handle is rotated, the worm 2 also rotates in conjunction with the worm shaft 21 so that the worm wheel 3 also rotates. It has become. A shaft body (not shown) is fixed at the center of the worm wheel 3, and the shaft body rotates as the worm wheel 3 rotates, and a valve body of a valve such as a butterfly valve connected to the gear unit 1. Is designed to rotate.
The worm wheel 3 is rotatable through O-rings 4b and 5b by a cylindrical shaft support 4a projecting from the inside of the box 4 and a cylindrical shaft support 5a projecting from the lower surface of the cover 5, respectively. It is supported.

  Next, the seal structure of the gear unit 1 will be described. FIG. 3 is a cross-sectional view showing a joint portion between the box 4 and the cover 5, and a seal structure 10 is provided at the joint portion. As shown in FIG. 3, the liquid gasket 8 is interposed between the wall end portion 61 of the box 4 and the joint portion 7 of the cover 5 at the joint portion. As the liquid gasket 8, one having elasticity after curing is used.

The width H1 of the contact surface 71 in contact with the liquid gasket 8 at the joint 7 of the cover 5 is at least a predetermined amount of shift between the box 4 and the cover 5 (t: see FIG. 4A). It is set wider than 61 width H2. The predetermined shift amount is a shift amount assumed in advance. For example, the maximum value of the deviation measured by experiment or simulation is set as a predetermined deviation, or the difference between the screw diameter of the bolt 9 and the inner diameter of the through hole of the cover 5 through which the bolt 9 penetrates is set to a predetermined value. For example, the amount of deviation may be set.
Here, the peripheral edge of the cover 5 has a one-stage shape that is a cut surface, and this processed surface serves as a joint 7. Further, the wall end portion 61 of the box 4 is formed with a notch 61 a so as to have a two-step shape with a low inner side, and faces the contact surface 71 at the joint portion 7 of the cover 5. That is, the liquid gasket 8 interposed between the upper step portion 62 and the contact surface 71 is formed in a thin film shape by sandwiching the liquid gasket 8 between the upper step portion 62 and the lower step portion 63 of the wall end portion 61 and the joint portion 7 of the cover 5. Thus, the liquid gasket 8 interposed between the lower step portion 63 and the contact surface 71 is filled in the notch 61a and becomes thicker than the portion located outside the notch 61a, that is, the thin film portion. Hereinafter, the thin film portion of the liquid gasket 8 is referred to as a thin film portion 81, and the thick portion is referred to as a thick portion 82. As a result, the width H4 of the contact surface 71 in contact with the thick portion 82 is longer than the width H3 of the upper surface of the lower step portion 63 in contact with the thick portion 82.

As shown in FIGS. 1 and 2, the seal structure 10 is formed over the entire circumference of the joint portion of the box 4 and the cover 5, so that the lubricating oil filled in the gear unit 1 from the joint portion is exposed to the outside. Leakage and entry of water from the outside are prevented.
The box 4 and the cover 5 are made of cast iron or the like. In the present embodiment, the wall end 61 of the box 4 has an upper step 62 formed by a cutting surface, and the lower step 63 is cast. The surface is formed. Here, when the wall end 61 is non-circular as shown in FIG. 2, it is preferable to form the lower step portion 63 at the time of casting formation in terms of processing efficiency. However, when the wall end 61 is annular. It is preferable to form by cutting.

Next, the operation of this embodiment will be described.
When the box 4 and the cover 5 are joined, the operator applies the liquid gasket 8 to the wall end 61 of the box 4 and then covers the opening O of the box 4 with the cover 5. Thereby, the wall end portion 61 of the box 4 and the joint portion 7 of the cover 5 face each other, and the joint portion (seal structure 10) between the box 4 and the cover 5 is formed via the liquid gasket 8. The cover 5 is fixed by screwing the bolt 9 to the box 4.
The amount of the liquid gasket 8 applied is such that the liquid gasket 8 is compressed by the box 4 and the cover 5 and protrudes inward of the box 4 from the width H2 of the wall end portion 61 of the box 4, and the inside of the notch 61a. The amount to be filled is set. Further, the liquid gasket 8 does not need to be in close contact over the entire contact surface 71 of the joint portion 7, as long as it protrudes wider than the width H <b> 2 of the wall end portion 61 in consideration of the maximum value of the displacement amount t of the cover 5 described later. Good.

  When a sudden impact or load is applied to the gear unit 1 when the valve mounted with the gear unit 1 assembled as described above is transported or piped, the box 4 and the cover 5 are shown in FIG. There is a case where it is shifted. In addition to these, the deviation may occur when an excessive force is applied to the shaft body from the handle. This is because, since the cover 5 pivotally supports the worm wheel 3, if an excessive force is applied from the handle to the shaft body, the worm wheel 3 is inclined and a force is applied in the direction of shifting the cover 5 from the box 4. to cause.

  4A is a diagram illustrating a shift state of the cover 5 in the upper left of FIG. 1 when the cover 5 is shifted in the right direction of FIG. 1, and FIG. 4B is a view in the upper right of FIG. It is a figure showing the shift state of the cover. As shown in FIG. 4A, when the cover 5 is shifted from the upper step 62 side to the lower step 63 side of the wall end portion 61, the liquid gasket 8 may be damaged and the thin film portion 81 of the gasket 8 may be peeled off. . Since the seal width of the liquid gasket 8 is set wider than the width H2 of the wall end portion 61 in consideration of the maximum value of the shift amount t of the cover 5, the sealing performance can be maintained. In addition, the thick portion 82 of the liquid gasket 8 having elasticity after curing follows the movement of the cover 5 and maintains the adhesion with the lower step portion 63 of the wall end portion 61 of the box 4 and the joint portion 7 of the cover 5. As a result, the sealing performance can be more reliably maintained.

  On the other hand, as shown in FIG. 4B, when the cover 5 is displaced from the lower step 63 side to the upper step 62 side of the wall end 61, the liquid gasket 8 is damaged and the thin film portion 81 of the gasket 8 is peeled off. There is. However, since the seal width of the liquid gasket 8 is set wider than the width H2 of the wall end portion 61 in consideration of the maximum value of the shift amount t of the cover 5, the sealing performance can be maintained. In particular, the width H4 of the contact surface 71 in contact with the thick portion 82 is longer than the width H3 of the upper surface of the lower step portion 63 in contact with the thick portion 82. The width H5 on the contact surface 71 side of the thick portion 82 can be ensured to be equal to or greater than the width H3 on the lower step portion 63 side. That is, even if the thin film portion 81 is peeled off, the width H5 on the contact surface 71 side of the thick portion 82 can be secured, and therefore leakage due to the peeling of the thin film portion 81 can be prevented by the thick portion 82.

  As described above, according to this embodiment, even if the box 4 and the cover 5 are displaced and the liquid gasket 8 is cut or peeled off due to sudden impact or excessive load, the wall in the liquid gasket 8 is removed. The portion protruding from the end 61 ensures the sealing performance between the box 4 and the cover 5. Since only the seal width of the liquid gasket 8 needs to be wider than the width of the wall end portion 61 by at least a predetermined shift amount between the box 4 and the cover 5, the shape of the gear unit 1 itself is significantly changed. Even if it is not, it becomes possible to ensure sealing performance.

It is needless to say that the present invention is not limited to the above embodiment and can be modified as appropriate.
For example, as shown by the dotted line portion P in FIGS. 4A and 4B, the corner portion of the notch 61a covered with the liquid gasket 8 (the corner portion 62a of the upper step portion 62 of the wall end portion 61) is formed in an arc shape. If this is the case, the stress concentration on the liquid gasket 8 due to the corners of the upper step 62 of the wall end 61 when the cover 5 is shifted from the lower step 63 side to the upper step 62 side of the wall end 61 is dispersed. It is possible to prevent the liquid gasket 8 from being damaged. Examples of means for forming the corner 62a in an arc shape include cutting and casting.

In the present embodiment, the wall end portion 61 of the box 4 has a two-stage shape, and the thick portion 82 is formed within the interval between the lower step portion 63 of the wall end portion 61 and the joint portion 7 of the cover 5. However, if the thick portion is formed in a state where the seal width of the liquid gasket is set to be wider than the width of the wall end portion 61 by at least a predetermined deviation amount between the box 4 and the cover 5, The shape of the wall end 61 of the box 4 and the shape of the joint 7 of the cover 5 are not limited to this. For example, as shown in FIG. 5 (a), the notch 61b is provided by forming the joint portion 7A of the cover 5A into a two-step shape, and the wall end portion 61A is formed as a plane to form the thick portion 82A. Alternatively, as shown in FIG. 5B, a thick portion 82B may be formed by expanding the application area of the liquid gasket 8B on the cover 5 side inward. Even in these cases, in order to disperse the stress concentration on the liquid gaskets 8A and 8B, it is preferable to form the corners (corner portions 71a, 71b and 61c) embedded in the liquid gaskets 8A and 8B in an arc shape. .
In the case of FIG. 5A, the notch 61b is set so that the seal width of the liquid gasket is set wider than the width of the wall end portion 61A by at least a predetermined deviation amount between the box 4 and the cover 5. It is necessary to form the upper surface of the substrate.

FIG. 1 is a side sectional view showing a schematic configuration of a gear unit of the present embodiment. It is a front view showing the schematic structure of the box with which the gear unit of FIG. 1 is equipped. It is a sectional side view showing the seal structure of the gear unit of FIG. It is explanatory drawing showing the state at the time of deviation | shift generation | occurrence | production of the seal structure of FIG. It is a figure showing the modification of the seal structure of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gear unit 2 Worm 3 Worm wheel 4 Box 4a Shaft support part 4b O-ring 5 Cover 5a Shaft support part 5b O-ring 6 Wall part 7 Joint part 8 Liquid gasket 9 Bolt 10 Seal structure 21 Warm shaft 41 Warm storage part 42 Wheel storage part 43 Bearing 44 Shaft body 61 Wall edge 62 Upper stage 63 Lower stage 71 Contact surface 81 Thin film part 82 Thick part O Opening part

Claims (3)

In a seal structure of a gear unit that has a bottomed box in which an opening is formed at the top by a wall covering the periphery and a cover that covers the opening, and a gear is built in the body.
The joint portion between the box and the cover is interposed between a wall end portion which is an upper end portion of the wall portion, a joint portion of the cover facing the wall end portion, and the wall end portion and the joint portion. The liquid gasket
The seal structure of the gear unit, wherein the seal width of the liquid gasket is set to be wider than the width of the wall end by at least a predetermined deviation amount between the box and the cover. The seal structure of the gear unit according to claim 1,
A cutout is provided in at least one of the wall end of the box or the joint of the cover,
A gear unit seal structure, wherein the liquid gasket is filled into the notch to form a thicker portion than the liquid gasket located outside the notch. The seal structure of the gear unit according to claim 2,
The gear unit seal structure, wherein a corner portion of the notch covered with the liquid gasket is formed in an arc shape.

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