Metal packing

Abstract

To provide metal packing used, e.g., in pipe connection sections of heat pump water heaters, the metal packing achieving all of the following effects with a simple structure: improved sealing performance; suppression of damage caused by excessive torque; and enhanced corrosion resistance.SOLUTION: The metal packing comprises: a metal washer having an inclined surface overall and substantially having a donut shape formed by punching a circular hole in a circular metal plate; and a rubber coating that covers the entire surface of the metal washer. The metal washer is formed with a predetermined height difference between the outer circumference of the circular hole and the outer circumference of the circular metal plate.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a metal packing used in pipe connections of a heat pump water heater. [Background technology]

[0002] A heat pump water heater is a water heater in which a heat pump unit that boils water to make hot water and a hot water storage unit that stores the boiled hot water are connected by piping. This heat pump water heater has multiple flow paths, such as a flow path that supplies water from the bottom of the hot water storage unit to the heat pump unit during boiling operation, and a flow path that supplies hot water from the heat pump unit to the top of the hot water storage unit during boiling operation. As described above, the latter flow path contains high-temperature hot water during boiling operation, but contains room-temperature water except when boiling operation is performed, so this flow path contains either hot water or water depending on the operating status of the water heater.

[0003] The sealing material of Patent Document 1 is known as a metal packing used in a piping connection where cold or hot water flows depending on the operating status of the water heater. For example, claim 1 of the same document states, "A water heater comprising a hot water pipe having a flange, a cylindrical connection port, and a sealing material made of a corrosion-resistant steel plate having a substantially doughnut disk shape, the sealing material having a thin film of rubber material tightly and integrally molded on the joint surface with the flange, the joint surface with the connection port, and the inner end surface, and also vulcanized, and no rubber material is present near the outer peripheral end surface," and claim 3 states, "The water heater according to claim 1 or 2, in which the sealing material is deformed to have steps of the same height in a concentric shape within the joint surface, and is made of a steel plate material having spring properties."

[0004] Furthermore, with regard to sealing material 12 in Figure 4 of the same document, paragraph 0045 states, "In the figure, 12 is a sealing material made of a springy steel plate material, attached to 12a in the shape of a leaf spring with rubber material tightly molded thereon. When cap nut 9 is tightened, step portion 12a of the sealing material becomes intimately attached to the joint with the rubber material having the compressed spring portion ensuring a seal." Paragraph 0046 states, "In addition, even if the hot water supply pipe 11 and connection port 5 are made of materials with significantly different thermal expansion coefficients, and their relative positions change due to a temperature difference, the springiness of sealing material 12 prevents a significant decrease in adhesion and ensures a seal."

[0005] Thus, Figure 4 of Patent Document 1 discloses a sealing material 12 made of springy steel plate material with no rubber material near the outer peripheral end face and covered with rubber material elsewhere. By using this sealing material 12, sealing performance is ensured at the piping connection part of the water heating device when the relative positions of the hot water pipe and the connection port change due to differences in the thermal expansion coefficients of the two. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-155965 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, the sealing material 12 in FIG. 4 of Patent Document 1 has the following problems.

[0008] (1) The sealing material 12 in the figure is generally doughnut-shaped, but its specific shape, as can be seen from the shape of the sealing material on the right side of the figure (before tightening), is composed of two parts: a flat part on the outermost periphery and an inclined part whose inner periphery is raised higher than the outer periphery. Therefore, with the sealing material 12 in the figure, the length of the inclined part that functions as a spring is shortened by providing the flat part, and as a result, there is a problem in that the range of relative position change that allows the sealing material 12 to maintain its sealing performance is also narrowed.

[0009] (2) When connecting pipe joints using male and female threads, it is necessary to tighten the joints with the torque specified by the water heater manufacturer to avoid leakage from the joints due to insufficient tightening and damage to the joints (especially plastic joints) due to overtightening. However, contractors who install water heaters do not always comply with the above-mentioned specified torque, and rather, general contractors tend to tighten the joints with excessive torque. In such cases, with the sealing material (metal packing) of Patent Document 1, which does not have a rubber material near the outer peripheral end face, the rubber material that receives excessive torque peels off from the steel plate and deforms significantly, which is a problem that liquid leakage is likely to occur from the deformed part of the rubber material (i.e., the deteriorated part of the seal).

[0010] (3) The sealing material in Patent Document 1 uses a corrosion-resistant steel plate, but since a steel plate with strong springiness generally has poor corrosion resistance, it is considered that the corrosion resistance of the steel plate used in the sealing material 12 in the figure is low. Therefore, the sealing material 12 in the figure, which has a configuration in which there is no rubber material near the outer peripheral end face, has a problem that corrosion easily progresses near the outer peripheral end face.

[0011] In consideration of the problems with the conventional technology as described above, the present invention aims to provide a metal packing that achieves the effects of improved sealing performance, suppression of damage when excessive torque is applied, and improved corrosion resistance with a simple configuration. [Means for solving the problem]

[0012] In order to solve the above problems, a metal packing is provided which comprises a metal washer having an approximately doughnut shape with a circular hole drilled in a circular metal plate and an inclined surface as a whole, and a rubber coating which covers the entire surface of the metal washer, and the metal washer is a metal packing in which a predetermined height difference is provided between the outer periphery of the circular hole and the outer periphery of the circular metal plate. Effect of the Invention

[0013] According to the metal packing of the present invention, it is possible to achieve the effects of improving sealing performance, suppressing damage when excessive torque is applied, and improving corrosion resistance with a simple configuration. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a cross-sectional view of a pipe connection portion of the water heater of the first embodiment. [Diagram 2] FIG. 2 is a top view of the metal packing of the first embodiment. [Diagram 3] FIG. 2 is a cross-sectional view of the metal packing of the first embodiment. [Figure 4A] FIG. 6 is a cross-sectional view of a metal packing according to a second embodiment of the present invention. [Figure 4B] 13 is a cross-sectional view of another example of the metal packing of Example 2. [Diagram 5] FIG. 11 is a cross-sectional view of a metal packing according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a motor drive device according to the present invention will be described with reference to the drawings. EXAMPLES

[0016] First, a metal packing 1 according to a first embodiment of the present invention will be described with reference to Figures 1 to 3. In this embodiment, the metal packing 1 used in a pipe connection part of a heat pump water heater is illustrated, but the metal packing 1 of the present invention may be used in a pipe connection part of other devices.

[0017] FIG. 1 is a cross-sectional view of a pipe connection through which cold or hot water flows depending on the operating condition of a heat pump water heater. Here, a state is shown in which a metal packing 1 of this embodiment is sandwiched in a gap Δ1 formed between a metal joint 2 having a female thread formed on the inner surface and a resin joint 3 having a male thread formed on the outer surface. Since the thermal expansion coefficients of the metal joint 2 (e.g., copper alloy) and the resin joint 3 (e.g., PPS (polyphenylene sulfide)) are significantly different, when cooling by the flow of low-temperature water (e.g., 20°C) and heating by the flow of high-temperature water (e.g., 90°C) are repeated, the appropriate tightening immediately after the installation of the water heater gradually loosens, and the gap Δ1 gradually expands. Therefore, the metal packing 1 of this embodiment has a configuration described later so that the necessary sealing performance can be maintained even when the gap Δ1 expands.

[0018] Fig. 2 is a top view of the metal packing 1 of this embodiment. As shown there, the top surface of the metal packing 1 is substantially doughnut-shaped. Also, Fig. 3 is a cross-sectional view of the metal packing 1 taken along the line AA in Fig. 2. As shown there, the metal packing 1 of this embodiment includes a metal washer 11, a rubber coating 12, and an adhesive 13 that firmly bonds them together.

[0019] As is obvious from FIG. 2, the metal washer 11 has a generally doughnut disk shape, and more specifically, a circular hole with an inner diameter D2 (for example, 12.5 mm) is drilled in a circular metal plate with a thickness t (for example, 1.5 mm) and an outer diameter D1 (for example, 18 mm). In addition, this metal washer 11 has a height difference Δ2 (for example, 0.2 mm) between the inner periphery (the outer periphery of the circular hole) and the outer periphery (the outer periphery of the circular metal plate) to give it springiness. In this example, the ratio of the height difference Δ2 to the thickness t is about 13%, but to give it appropriate springiness, the height difference Δ2 may be set in the range of 10 to 20% of the thickness t.

[0020] The rubber coating 12 is a rubber material that coats the entire surface of the metal washer 11 with a substantially uniform thickness (for example, 0.3 mm). As described above, in this embodiment, the metal washer 11 is given springiness, but stainless steels with excellent springiness (for example, SUS304 and SUS316) tend to have poor corrosion resistance. Therefore, in this embodiment, the corrosion resistance of the metal packing 1 as a whole is improved by coating the entire metal washer 11, which has poor corrosion resistance, with a rubber material.

[0021] The operation of the metal packing 1 of this embodiment will be described below for each situation.

[0022] <Effects of Metal Packing 1 when fittings are tightened to the torque specified by the manufacturer> As is obvious from the cross-sectional view of Figure 1, when a contractor tightens the metal joint 2 and the resin joint 3 with an appropriate torque when installing a water heater, the inclined surface of the metal packing 1 is appropriately crushed, the height difference Δ2 becomes small, and the metal packing 1 is deformed into a substantially flat shape. At this time, due to the spring property of the metal packing 1, the outermost periphery of the lower surface of the metal packing 1 is pressed against the metal joint 2, and the outermost periphery of the upper surface of the metal packing 1 is pressed against the resin joint 3. Therefore, high surface pressure can be secured at the contact area between the metal packing 1 and the metal joint 2 and at the contact area between the metal packing 1 and the resin joint 3, and high sealing performance as a piping connection can be maintained.

[0023] <Effects of metal packing 1 when gap Δ1 gradually expands> As mentioned above, the linear expansion coefficients of the metal joint 2 and the resin joint 3 are significantly different, so when hot and cold water are repeatedly passed through the piping connection, the gap Δ1 shown in Fig. 1 gradually expands. At this time, the metal packing 1 tries to return to its original shape shown in Fig. 3, so if the amount of expansion of the gap Δ1 is less than the height difference Δ2 of the metal packing 1, the metal packing 1 continues to function as a spring, and can maintain high surface pressure at both the contact point with the metal joint 2 and the contact point with the resin joint 3, and the piping connection can maintain high sealing performance.

[0024] As shown in FIG. 3, by making the entire metal washer 11 an inclined surface, the entire metal washer 11 can be given spring properties, so that the size of the gap Δ1 that can maintain sealing properties can be increased compared to the configuration in FIG. 4 of Patent Document 1 in which a flat portion is provided only on a portion of the metal washer.

[0025] <Effects of Metal Packing 1 when fittings are tightened with excessive torque> Next, the action of the metal packing 1 in the case where a construction worker or the like tightens the metal joint 2 and the resin joint 3 with excessive torque when installing the water heater will be described.

[0026] As is obvious from Fig. 1, when the metal joint 2 and the plastic joint 3 are fastened with excessive torque, the rubber coating 12 on the upper surface of the substantially flat metal packing 1 after deformation receives a shear force from the lower surface of the plastic joint 3 rotating around the axis. However, as shown in Fig. 3, the metal packing 1 of this embodiment is covered with the rubber coating 12 even in the vicinity of the outer peripheral end face, so not only are the upper and lower surfaces of the rubber coating 12 connected all around, but the metal washer 11 and the rubber coating 12 are firmly bonded with the adhesive 13. Therefore, unless the degree of the shear force caused by the excessive fastening torque is extreme, the rubber coating 12 bonded with the adhesive 13 will not peel off from the metal washer 11 and deform significantly, or the deformed portion of the rubber coating 12 will not deteriorate the seal and cause liquid leakage.

[0027] <Effects of this embodiment> As described above, the metal packing of this embodiment can achieve the effects of improving sealing performance, suppressing damage when excessive torque is applied, and improving corrosion resistance with a simple configuration. EXAMPLES

[0028] Next, a metal packing 1 according to a second embodiment of the present invention will be described with reference to Figures 4A and 4B. Note that a duplicated description of the points common to the first embodiment will be omitted.

[0029] As mentioned in <Function of the metal packing 1 when the joint is tightened with excessive torque> in Example 1, if a contractor tightens the metal joint 2 and the plastic joint 3 with an extremely excessive torque, the rubber coating 12 may peel off from the metal washer 11, causing deterioration of the seal.

[0030] Therefore, in this embodiment, as shown in Fig. 4A, an annular recess 12a, i.e., a mechanically weak portion, is intentionally provided on the side of the rubber coating 12 that covers the metal packing 1. This ensures that the portion that will break when the metal joint 2 and the resin joint 3 are tightened with an extremely excessive torque will be a portion that is less affected by the deterioration of the sealing performance of the metal packing 1.

[0031] As shown in FIG. 4B, even if an annular recess 12b is provided in the center of the upper surface of the rubber material coating 12 covering the metal packing 1, the same effect as that of the metal packing 1 in FIG. 4A can be obtained. EXAMPLES

[0032] Next, a metallic packing 1 according to a third embodiment of the present invention will be described with reference to Fig. 5. Note that a duplicated description of points common to the above-mentioned embodiments will be omitted.

[0033] In the metal packing 1 of Examples 1 and 2, an adhesive 13 was used to firmly bond the metal washer 11 and the rubber material coating 12, but since the rubber material coating 12 of the present invention covers the entire surface of the metal washer 11 without exception, the rubber material coating 12 as a structure has a sufficient strength even if the adhesive 13 is omitted.

[0034] Therefore, even with the metal packing 1 of this embodiment in which the adhesive 13 is omitted, it is possible to obtain a shear force resistance performance that is not much inferior to that of the metal packing 1 of the above embodiment. [Explanation of symbols]

[0035] 1 Metal packing 11 Metal washer 12 Rubber coating 12a, 12b Recess 13. Glue 2 Metal fittings 3 Plastic joints Δ1 Gap Δ2 Height difference

Claims

1. A metal washer having a generally doughnut-shaped shape with a circular hole drilled in a circular metal plate and an inclined surface as a whole; a rubber coating covering the entire surface of the metal washer; A metal packing comprising: The metal packing is characterized in that the metal washer has a predetermined height difference between the outer periphery of the circular hole and the outer periphery of the circular metal plate.

2. The metal packing according to claim 1, The metal packing is characterized in that the height difference is 10 to 20% of the thickness of the metal washer.

3. The metal packing according to claim 1, The metal packing is characterized in that the rubber coating has a recess on the side or in the center of the top surface.

4. The metal packing according to claim 1, A metal packing characterized in that the metal washer and the rubber coating are bonded together via an adhesive.

5. The metal packing according to claim 1, The metal packing is characterized in that the metal washer is made of SUS304 or SUS316.

6. The metal packing according to any one of claims 1 to 5, A metal gasket characterized by being placed between a metal joint and a resin joint at a piping connection part of a heat pump water heater.

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