Rod packing

Abstract

To provide a rod packing that has fewer components, allows easy assembly, and exhibits enhanced sealing performance.SOLUTION: Provided is a rod packing 10 that is fixed to a packing case 3 in a state of being brought into contact with an outer periphery of a piston rod 2 of a cylinder 1, and suppresses fluid leakage from the outer periphery of the sliding piston rod 2. The rod packing includes a plurality of divided packing pieces 11, and is configured such that the plurality of packing pieces 11, in a mutually fitted state, is pressed radially inward from the outer periphery by a biasing member. In the mutually fitted state, the plurality of packing pieces 11 has no grooves penetrating in the radial and axial directions of the piston rod 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rod packing that is fitted onto the outer periphery of a piston rod of a cylinder and fixed to a packing case, and that prevents fluid from leaking from the outer periphery of the sliding piston rod. [Background technology]

[0002] Conventionally, rod packing has been known in which a pair of annular packing rings provided in a packing case are fitted onto the outer periphery of a piston rod to prevent fluid from leaking from the outer periphery of a sliding piston rod (for example, Patent Document 1).

[0003] Also, as disclosed in Patent Document 2, for example, a rod packing is known in which three divided ring segments are fitted together to suppress leakage of fluid from the outer periphery of a piston rod. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-109016 A (particularly FIG. 1) [Patent Document 2] Japanese Patent Publication No. 2022-520732 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the conventional rod packing of Patent Document 1 requires two packing rings to achieve a sealing effect, which means that the number of parts cannot be reduced and assembly is time-consuming.

[0006] Furthermore, the rod packing of Patent Document 2 has a groove formed on one side in the axial direction that penetrates in the radial direction, which causes problems with sealing performance.

[0007] The present invention has been made in view of the above points, and its object is to provide a rod packing that has a small number of parts, is easy to assemble, and exhibits higher sealing performance. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention is made so that sealing performance can be ensured with a single packing ring that does not have a groove that penetrates in the axial and radial directions.

[0009] Specifically, in the first invention, The rod packing is fixed to a packing case in contact with the outer periphery of a piston rod of a cylinder, and prevents fluid from leaking from the outer periphery of the sliding piston rod. The rod packing is It has a plurality of divided packing pieces, The plurality of packing pieces are configured to be pressed radially inward from the outer periphery by a biasing member while being fitted together, When the plurality of packing pieces are fitted together, the piston rod does not have any grooves that penetrate in the radial and axial directions.

[0010] With the above configuration, the rod packing does not have grooves that penetrate the piston rod in the radial and axial directions, so no additional auxiliary packing is required, and the rod packing alone can suppress fluid leakage from the high-pressure side to the low-pressure side, and the width of the rod packing can be reduced. Also, since it is not necessary to position the through groove side on the high-pressure side as in the conventional case, there is no need to specify the orientation of the high-pressure side or the low-pressure side, making assembly easier.

[0011] In the second invention, in the first invention, The plurality of packing pieces have the same shape.

[0012] According to the above configuration, it is not necessary to change the shape for each packing piece, the number of types of parts is reduced, and part management and assembly work are also made easier.

[0013] In a third aspect of the present invention, in the first or second aspect of the present invention, The packing piece is an arc-shaped inner peripheral surface that is in sliding contact with the outer periphery of the piston rod; a first end portion on one circumferential side, the first end portion having a radially inner wall portion on the radially inner side; a second end portion on the other circumferential side, the second end portion having a radially outer wall portion that is notched radially outward and abuts against the radially inner wall portion, When the plurality of packing pieces are fitted between the first end portion and the second end portion, the radially inner wall portion and the radially outer wall portion are configured to be in sliding contact with each other and to be able to expand and contract in diameter, the radially inner wall portion is recessed on one axial side and is continuous with a first recessed portion having a first inner wall portion with which the radially outer wall portion of the second end portion slides; The radially outer wall portion is recessed on the other axial side and is configured to be continuous with a second recessed portion that is in sliding contact with the first recessed portion of the first end portion.

[0014] According to the above configuration, the rod packing can be configured to be expandable and contractable in diameter with a simple configuration and with a plurality of packing pieces fitted together.

[0015] In a fourth aspect of the present invention, in the third aspect of the present invention, With the plurality of packing pieces fitted together, a first pocket is formed in the first recessed portion on one axial side, the first pocket being closed radially outward by the first end portion; a second pocket is formed in the second recessed portion on the other axial side, the second pocket being closed radially outward by the first end portion; The first pocket and the second pocket do not penetrate the piston rod in the radial and axial directions.

[0016] According to the above configuration, the first pocket and the second pocket ensure sliding space, and the rod packing can be configured to be expandable and contractible with multiple packing pieces fitted in place, and a configuration can be realized that does not have grooves that penetrate the piston rod in the radial and axial directions.

[0017] In the fifth invention, in the fourth invention, An inner groove portion extending in a circumferential direction is formed on the arc-shaped inner peripheral surface, The inner groove is continuous with the first pocket or the second pocket.

[0018] According to the above configuration, the inner circumferential groove portion that is continuous with the first pockets or second pockets that are arranged in multiple locations in the circumferential direction introduces pressure from the first pockets or second pockets, balancing the pressure in the circumferential direction while preventing leakage, and reducing the pressure load on the packing.

[0019] In a sixth aspect of the present invention, in the first or second aspect of the present invention, The number of packing pieces is three.

[0020] According to the above configuration, the number of parts is reduced compared to a configuration with four or more packing pieces, assembly is easy, and leakage of fluid around the outer periphery of the piston rod is easily suppressed. [Effects of the Invention]

[0021] As described above, according to the present invention, the number of parts is small, assembly is easy, and higher sealing performance can be achieved. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a perspective view showing a rod packing according to an embodiment of the present invention. [Figure 2A] FIG. 10 is a perspective view showing an example of use of a rod packing. [Figure 2B] FIG. 2B is a cross-sectional view taken along line IIB-IIB in FIG. 2A. [Figure 3A] FIG. [Figure 3B] FIG. [Figure 3C] FIG. 2 is a left side view showing the rod packing. [Figure 3D]FIG. 4 is a right side view showing the rod packing. [Figure 3E] FIG. 2 is a plan view showing a rod packing. [Figure 3F] FIG. [Figure 4A] FIG. [Figure 4B] FIG. [Figure 4C] FIG. [Figure 4D] FIG. [Figure 4E] FIG. [Figure 4F] FIG. [Figure 5] FIG. 10 is a perspective view showing a rod packing according to a modified example of the embodiment of the present invention. [Figure 6] FIG. 10 is a perspective view of a rod packing according to a modified example of the embodiment of the present invention, viewed from the opposite side. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0024] As shown in FIGS. 1 to 3F, a rod packing 10 according to this embodiment is fixed to, for example, a packing case 3 provided on the rod portion of a compressor (not shown) in a state in contact with the outer periphery of a piston rod 2 of a cylinder 1. The piston rod 2 reciprocates with the rotational motion of the compressor's crank, and serves to compress gas in a compression chamber by means of a piston head at the tip. This rod packing 10 is provided to prevent gas from leaking from this compression chamber. A plurality of rod packings 10 may be provided in the packing case 3, lined up in the axial direction. The pressure range is not particularly limited.

[0025] The material of the rod packing 10 is, for example, filled polytetrafluoroethylene (PTFE) blended with fillers such as carbon fiber, glass fiber, carbon, and heat-resistant resin. The blending ratio is 2% to 50% filler, with PTFE being 50% to 98%, making PTFE the main material. The blending ratio and blending ingredients are not limited to these. Furthermore, the main material is not limited to polytetrafluoroethylene (PTFE), and other injection-moldable resins with excellent heat resistance and sliding properties, such as polyether ether ketone (PEEK) and polyphenylene sulfide (PPS), may also be used.

[0026] The rod packing 10 has, for example, three divided packing pieces 11. As shown in Figures 4A to 4F, each packing piece 11 has an arc-shaped inner peripheral surface 12 that comes into sliding contact with the outer periphery of the cylindrical piston rod 2, and when the three packing pieces 11 are fitted together, they come into contact with the entire outer periphery of the piston rod 2.

[0027] The three packing pieces 11 are configured to be pressed radially inward with the three pieces fitted together by a biasing member (not shown) provided in the outer groove 13 on the outer periphery. The biasing member is, for example, a circular tension coil spring when viewed from the axial direction of the piston rod 2, but may be any other configuration such as a ring-shaped elastic member as long as it can exert a compressive force in the circumferential direction (and consequently in the radial direction).

[0028] One of the features of this embodiment is that the rod packing 10 does not have grooves that penetrate the piston rod 2 in the radial and axial directions when the plurality of packing pieces 11 are fitted together.

[0029] In this embodiment, the three packing pieces 11 have the same shape, and when fitted together, form a circular ring.

[0030] 4A to 4F, the packing piece 11 has, on one circumferential side, a first end portion 11a having a radially inner wall portion 14 on the radially inner side. The radially inner wall portion 14 extends linearly in a direction perpendicular to the radial direction as viewed from the axial direction of the rod packing 10 when the three packing pieces 11 are fitted together, so that the first end portion 11a is tapered.

[0031] On the other hand, on the other circumferential side, a second end 11b is formed, which has a radially outer wall portion 16 cut out radially and abutting against the radially inner wall portion 14. The radially outer wall portion 16 extends linearly in a direction perpendicular to the radial direction as viewed from the axial direction of the rod packing 10 when the three packing pieces 11 are fitted together, so that the second end 11b is tapered.

[0032] As shown in Figures 3A to 3F, when the three packing pieces 11 are fitted with the first end 11a and the second end 11b, the radially inner wall portion 14 and the radially outer wall portion 16 are configured to be able to expand and contract in diameter while sliding in contact with each other, for example, as shown by the arrows in Figures 3A and 3B.

[0033] 4A, radially inner wall portion 14 is recessed on one axial side and continues to first recessed portion 15 having first inner wall portion 15a (on the same line as radially inner wall portion 14 when viewed from the axial direction) with which radially outer wall portion 16 of second end portion 11b slides. First recessed portion 15 is formed to a predetermined depth so that a wall portion remains on the other axial side.

[0034] 4B, radially outer wall portion 16 is recessed on the other axial side and continues to second recessed portion 17 that slides against first recessed portion 15 of first end portion 11a. Second recessed portion 17 has vertical wall portion 17a that is perpendicular to radially outer wall portion 16. The depth of second recessed portion 17 is shallower than the depth of first recessed portion 15.

[0035] 1 and 3A, in a state in which the three packing pieces 11 are fitted together, a first pocket 18 is formed in the first recessed portion 15 on one axial side, the radially outer side of which is closed by the first inner wall portion 15a of the first end portion 11a, and a second pocket 19 is formed in the second recessed portion 17 on the other axial side, the radially outer side of which is closed by the radially inner wall portion 14 of the first end portion 11a, as shown in Fig. 3B. Thus, in this embodiment, the first pocket 18 and the second pocket 19 do not penetrate the piston rod 2 in the radial and axial directions.

[0036] In this embodiment, the shape of the packing pieces 11 is as described above, so that the rod packing 10 can be configured to be expandable and contractible in diameter with a simple configuration and with multiple packing pieces 11 fitted together.

[0037] In this embodiment, the number of packing pieces 11 is three, which has the advantage of reducing the number of parts compared to a configuration with four or more packing pieces, facilitating assembly, and reducing the number of divided surfaces, making it easier to suppress fluid leakage from the outer periphery of the piston rod 2. The number of packing pieces 11 may also be two. With two, the number of parts is fewer, but there will be two first pockets and two second pockets.

[0038] In addition, in this embodiment, the three packing pieces 11 have the same shape, so there is no need to change the shape for each packing piece 11, reducing the number of different parts and facilitating assembly work. Although it is not necessary for all three pieces to have the same shape, it is particularly preferable to have two or three packing pieces 11 of the same shape.

[0039] Next, the operation of the rod packing 10 according to this embodiment will be described. As described above, the rod packing 10 is fixed to the packing case 3 provided on the rod portion of the compressor in a state where it is in contact with the outer periphery of the piston rod 2.

[0040] The rod packing 10 is assembled by assembling three packing pieces 11 in a circular shape, with the first end 11a of one packing piece 11 fitted into the second end 11b of the adjacent packing piece 11, and fitting a ring-shaped coil spring into the outer groove 13. The rod packing 10 is then fixed to the packing case 3 in a state where it is appropriately fastened to the outer periphery of the piston rod 2. In this embodiment, the rod packing 10 is fixed to the packing case 3 of the rod portion of the compressor so that the first pocket 18, which is connected to the inner groove 20, faces the high-pressure side. The piston rod 2 reciprocates with the rotation of the compressor's crank, compressing gas in the compression chamber with the piston head at the tip. The rod packing 10 slides against the outer periphery of the sliding piston rod 2 to prevent gas from leaking from the compression chamber. In this case, leakage from the compression chamber to the rod side can be suppressed not only when the compression chamber is under high pressure, but also under all pressure conditions during the compression stroke.

[0041] In this embodiment, the rod packing 10 does not have a groove that penetrates the piston rod 2 in the radial and axial directions, so there is no need to provide a packing to seal gas leaking from the groove, and the rod packing 10 can suppress leakage of fluid from the high-pressure side to the low-pressure side, and as a result, the width of the rod packing 10 can be reduced.

[0042] Furthermore, in this embodiment, the first pocket 18 and the second pocket 19 allow the rod packing 10 to be configured to be expandable and contractible in diameter while ensuring a sliding space when multiple packing pieces 11 are fitted together, and a configuration can be realized that does not have grooves that penetrate the piston rod 2 in the radial and axial directions.

[0043] Therefore, the rod packing 10 according to this embodiment has a small number of parts, is easy to assemble, and can exhibit higher sealing performance.

[0044] -Variations- 5 and 6 show a rod packing 110 according to a modified example of the embodiment of the present invention, which differs from the above-described embodiment in particular in the position of the inner groove portion 120. In this modified example, the same parts as those in Figures 1 to 4F have been designated by reference numerals in the 100s, and detailed descriptions thereof will be omitted.

[0045] The second pocket 119 in the packing piece 111 of this modified example is deeper than the first pocket 118 , and the inner groove 120 communicates with the second pocket 119 .

[0046] In this modification, the tip of first end 111a is thin and the second end 111b is thick to adjust the depth of first pocket 118 and second pocket 119. The thicker the tip, the easier it is to provide inner groove 120.

[0047] Rod packing 110 of this modified example can be applied when second pocket 119 side is the high pressure side (for example, the compression chamber side of the compressor), and provides the same effects as those of the above embodiment.

[0048] (Other embodiments) The present invention may be configured as follows in relation to the above embodiment.

[0049] That is, the thickness of the first pockets 18, 118 and the second pockets 19, 119 may be changed as appropriate, but basically it is preferable to form the inner grooves 20, 120 on the deeper side.

[0050] On the other hand, it is not necessary to provide the inner grooves 20, 120. If the inner grooves 20, 120 are not provided, there is no need to specify the direction of the high pressure side or low pressure side, making assembly easier.

[0051] The above-described embodiments are essentially preferred examples, and are not intended to limit the scope of the present invention, its applications, or uses. [Explanation of symbols]

[0052] 1 cylinder 2 piston rods 3 Packing case 10,110 Rod packing 11,111 Packing pieces 11a,111a 1st end 11b,111b 2nd end 12,112 Circular inner surface 13,113 Outer groove 14,114 Radial inner wall 15,115 First recess 15a,115a 1st inner wall part 16,116 Radial outer wall 17,117 Second recess 17a,117a Vertical wall section 18,118 First pocket 19,119 Second pocket 20,120 Inner groove

Claims

1. A rod packing (10, 110) is fixed to a packing case (3) in contact with the outer periphery of a piston rod (2) of a cylinder (1), and prevents fluid from leaking from the outer periphery of the sliding piston rod (2), A packing piece (11, 111) divided into a plurality of pieces is provided. The plurality of packing pieces (11, 111) are configured to be pressed radially inward from the outer periphery by a biasing member while being fitted together, When the plurality of packing pieces (11, 111) are fitted together, the piston rod (2) does not have a groove penetrating in the radial and axial directions. A rod packing (10, 110) characterized by:

2. The plurality of packing pieces (11, 111) have the same shape. The rod packing (10, 110) of claim 1.

3. The packing pieces (11, 111) an arc-shaped inner peripheral surface (12, 112) that slides against the outer periphery of the piston rod (2); a first end portion (11a, 111a) on one circumferential side and having a radially inner wall portion (14, 114) on the radially inner side; a second end portion (11b, 111b) on the other circumferential side, the second end portion (11b, 111b) having a radially outer wall portion (16, 116) that is notched radially outward and abuts against the radially inner wall portion (14, 114); When the first end portions (11a, 111a) and the second end portions (11b, 111b) of the plurality of packing pieces (11, 111) are fitted together, the radially inner wall portion (14, 114) and the radially outer wall portion (16, 116) are configured to be expandable and contractable in diameter while being in sliding contact with each other, the radially inner wall portion (14, 114) is recessed on one axial side and is continuous with a first recessed portion (15, 115) having a first inner wall portion (15a, 115a) with which the radially outer wall portion (16, 116) of the second end portion (11b, 111b) slides; The radially outer wall portion (16, 116) is recessed on the other axial side and continues to a second recess portion (17, 117) that is in sliding contact with the first recess portion (15, 115) of the first end portion (11a, 111a). A rod packing (10, 110) according to claim 1 or 2.

4. In a state where the plurality of packing pieces (11, 111) are fitted together, a first pocket (18, 118) is formed in the first recessed portion (15, 115) on one axial side, the first pocket (18, 118) being closed radially outward by the first end portion (11a, 111a); a second pocket (19, 119) is formed in the second recessed portion (17, 117) on the other axial side, the second pocket (19, 119) being closed radially outward by the first end portion (11a, 111a); The first pocket (18, 118) and the second pocket (19, 119) do not penetrate the piston rod (2) in the radial and axial directions. The rod packing (10, 110) according to claim 3.

5. An inner groove portion (20, 120) extending in the circumferential direction is formed on the arc-shaped inner peripheral surface (12, 112), The inner groove (20, 120) is continuous with the first pocket (18, 118) or the second pocket (19, 119). The rod packing (10, 110) according to claim 4.

6. The number of the packing pieces (11, 111) is three. A rod packing (10, 110) according to claim 1 or 2.

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