Expansion tank capable of preventing internal leakage

Abstract

The present invention disclosed an expansion tank comprises a metal vessel including an upper barrel and a lower barrel, a plastic liner disposed inside the upper barrel of the metal vessel, a flexible diaphragm disposed inside the plastic liner, an inner metal ring disposed inside the flexible diaphragm, and an outer metal ring disposed between the upper barrel and the plastic liner, wherein a bottom annular section of the flexible diaphragm and a bottom annular section of the plastic liner are disposed between the inner metal ring and the outer metal ring, and the inner and outer metal rings clamp the bottom annular section of the flexible diaphragm and the bottom annular section of the plastic liner.

Description

FIELD OF INVENTION

[0001] The present invention relates to an expansion tank, particularly, to an expansion tank capable of preventing internal leakage.RELATED PRIOR ART

[0002] Expansion tanks are widely used in water piping systems to balance water pressure. Expansion tanks are also commonly connected to water treatment devices, such as reverse osmosis water purifiers, for storing the purified water produced by such devices. In addition, expansion tanks are also used in hydraulic systems.

[0003] FIGS. 5 and 6 illustrate the structure of a conventional expansion tank. In this structure, a lower end portion 931 of a rubber flexible diaphragm 93 and a lower end portion 941 of a plastic liner 94 are tightly clamped between a lower end portion 911 of a metal vessel 91 and a metal ring 92, forming a variable-volume water storage chamber 95 between the rubber flexible diaphragm 93 and the plastic liner 94, and a variable-volume air storage chamber 96 between the lower half of the metal vessel 91 and the rubber flexible diaphragm 93. The water storage chamber 95 communicates with a connector 97, which is connected to the aforementioned water piping system or reverse osmosis water purifier, allowing water to enter and exit the water storage chamber 95 through the connector 97. The air storage chamber 96 communicates with an inflation valve (not shown in the figures), through which air may be introduced into or released from the air storage chamber 96.

[0004] Under normal conditions, because the lower end portion 931 of the rubber flexible diaphragm 93 and the lower end portion 941 of the plastic liner 94 are tightly clamped between the lower end portion 911 of the metal tank 91 and the metal ring 92, the lower end portion 941 of the plastic liner 94 should closely abut the lower end portion 931 of the rubber flexible diaphragm 93. Therefore, water in the water storage chamber 95 is not expected to leak into the air storage chamber 96. However, in practice, the internal leakage issue that the water from the water storage chamber 95 leaks into the air chamber 96, still occurs. This issue of internal leakage is not uncommon and remains an urgent problem to be addressed.SUMMARY OF INVENTION

[0005] According to the applicant's research, as shown in FIG. 7, when water with high-pressure flows from a pipeline into the water storage chamber via the connector and is stored therein, the internal pressure of the water storage chamber increases. This pressure compresses the air in the air storage chamber by the rubber flexible diaphragm, thereby increasing the internal pressure of the air storage chamber to a level equal to that of the water storage chamber. At this time, the pressure within the water storage chamber continues to exert force on the plastic liner and the metal tank, which is in contact with the plastic liner. The pressure inside the air chamber likewise continues to exert force on the metal tank. When the internal pressure described above exceeds the external pressure outside the metal tank, the metal tank is pushed outward and deformed due to the internal pressure, causing deformation of the lower end portion of the metal tank as well. Consequently, a gap forms between the lower end portion of the plastic liner and the lower end portion of the rubber flexible diaphragm. As a result, water in the water storage chamber may be forced through this gap into the air chamber, thereby leading to the aforementioned internal leakage issue.

[0006] To address the aforementioned problem of internal leakage, the present invention provides an expansion tank, comprising a metal vessel including an upper barrel and a lower barrel, a plastic liner disposed inside the upper barrel of the metal vessel, a flexible diaphragm disposed inside the plastic liner, an inner metal ring disposed inside the flexible diaphragm, and an outer metal ring disposed between the upper barrel and the plastic liner, wherein a bottom annular section of the flexible diaphragm and a bottom annular section of the plastic liner are disposed between the inner metal ring and the outer metal ring while the inner and outer metal rings clamp the bottom annular section of the flexible diaphragm and the bottom annular section of the plastic liner.

[0007] In one embodiment, the inner metal ring of the expansion tank closely abuts an inner wall surface of the bottom annular section of the flexible diaphragm, an outer wall surface of the bottom annular section of the flexible diaphragm closely abuts an inner wall surface of the bottom annular section of the plastic liner, and an outer wall surface of the bottom annular section of the plastic liner closely abuts an inner wall surface of the outer metal ring, forming a water storage compartment between the flexible diaphragm and the plastic liner, and an air storage compartment between the flexible diaphragm and the lower barrel, and the water storage compartment and the air storage compartment are not in communication.

[0008] In one embodiment, an outer wall surface of the outer metal ring of the expansion tank closely abuts a bottom annular section of the upper barrel.

[0009] In another embodiment, the inner metal ring of the expansion tank is inwardly recessed to form an annular recess, the inner wall surface of the bottom annular section of the flexible diaphragm protrudes inwardly to form an annular protrusion, the annular recess of the inner metal ring receives the annular protrusion of the flexible diaphragm, and the two are tightly abutted against each other.

[0010] In one embodiment, the outer wall surface of the bottom annular section of the flexible diaphragm of the expansion tank is inwardly recessed to form an annular recess, the inner wall surface of the bottom annular section of the plastic liner protrudes inwardly to form an annular protrusion, the annular recess of the flexible diaphragm receives the annular protrusion of the plastic liner, and the two are tightly abutted against each other.

[0011] In another embodiment, the outer wall surface of the bottom annular section of the plastic liner of the expansion tank is inwardly recessed to form an annular recess, the inner wall surface of the outer metal ring protrudes inwardly to form an annular protrusion, the annular recess of the plastic liner receives the annular protrusion of the outer metal ring, and the two are tightly abutted against each other.

[0012] In yet another embodiment, the outer wall surface of the outer metal ring of the expansion tank is inwardly recessed to form an annular recess, a bottom annular section of the upper barrel protrudes inwardly to form an annular protrusion, the annular recess of the outer metal ring receives the annular protrusion of the upper barrel, and the two are tightly abutted against each other.

[0013] In one embodiment, a longitudinal section of the annular recess of the inner metal ring of the expansion tank is inwardly concave, while a longitudinal section of the annular protrusion of the flexible diaphragm is inwardly convex, and a longitudinal section of the flexible diaphragm is inwardly concave, while a longitudinal section of the annular protrusion of the plastic liner is inwardly convex, and a longitudinal section of the plastic liner is inwardly concave, a longitudinal section of the annular protrusion of the outer metal ring is inwardly convex, a longitudinal section of the outer metal is inwardly concave, a longitudinal section of the annular protrusion of the upper barrel is inwardly convex.

[0014] In another embodiment, the width of the outer metal ring of the expansion tank is greater than the width of the inner metal ring.

[0015] In one embodiment, the outer mental ring further includes an upper sheet extending upward from its annular protrusion and a lower sheet extending downward from the annular protrusion.BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1 is an exploded view of an expansion tank in accordance with the preferred embodiment of the invention.

[0017] FIG. 2 is a cross-section of the preferred embodiment of the present invention.

[0018] FIG. 3 and FIG. 4 are partial cross-sectional views of the preferred embodiment of the present invention near the inner metal ring 5.

[0019] FIG. 5 shows a cross-sectional view of a conventional expansion tank in an empty state.

[0020] FIG. 6 is an enlarged partial cross-sectional view of FIG. 5.

[0021] FIG. 7 is a cross-sectional view of a conventional expansion tank in a filled state.DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

[0022] FIGS. 1 to 3 illustrate an embodiment of the expansion tank according to the present invention. The expansion tank includes an upper barrel 1, a lower barrel 2, a connector 11 secured to the upper barrel 1, an inflation valve 21 secured to the lower barrel 2, a plastic liner 3 disposed inside the upper barrel 1, a flexible diaphragm 4 disposed within the plastic liner 3, an inner metal ring 5 disposed inside the flexible diaphragm 4, and an outer metal ring 6 disposed between the plastic liner 3 and the upper barrel 1. In this embodiment, both the upper barrel 1 and the lower barrel 2 are made of metal sheet material (e.g. iron plate) and after being joined end-to-end and welded together, form a metal vessel 100, but not limited as such. The inflation valve 21 is preferably threadedly engaged to the bottom of the lower barrel2, but not limited. The plastic liner 3 is made of a non-foamed plastic material and may be made of polypropylene (PP), polyethylene (PE), or other plastic materials. The flexible diaphragm 4 is preferably made of rubber or silicone, but not limited. Both the inner metal ring 5 and the outer metal ring 6 are made of metal sheet material (e.g. iron sheet).

[0023] As shown in FIGS. 1 and 2, the plastic liner 3 has a figure similar to and slightly smaller than that of the upper barrel 1. In this embodiment, the connector 11 is preferably made of stainless steel and is welded to a top portion of the upper barrel 1. An end portion 111 of the connector 11 extends through the upper barrel 1 and is inserted into a through hole 33 of the plastic liner 3. After the end portion 111 is riveted, it is tightly pressed against a top region of the plastic liner 3 while the top region surrounds the through hole 33. Although not explicitly shown in the Figures, in this embodiment, a metal washer and an O-ring are tightly clamped between the end portion 111 and the top region of the plastic liner 3. Additionally, a rubber gasket for preventing water leakage is also tightly clamped between the plastic liner 3 and the upper barrel 1.

[0024] As shown in FIG. 3, the inner metal ring 5 is inwardly recessed to form an annular recess 51, and the longitudinal section of the annular recess 51 is inwardly concave. A bottom annular section 41 of the flexible diaphragm 4 surrounds and faces the inner metal ring 5. An inner wall surface of the bottom annular section 41 of the flexible diaphragm 4 protrudes inwardly to form an annular protrusion 411, and the longitudinal section of the annular protrusion411 is inwardly convex. An outer wall surface of the bottom annular section 41 of the flexible diaphragm 4 is inwardly recessed to form an annular recess 412, and the longitudinal section of the annular recess 412 is inwardly concave. The annular recess 51 of the inner metal ring 5 receives the annular protrusion 411 of the flexible diaphragm 4, and the two are tightly abutted against each other.

[0025] A bottom annular section 31 of the plastic liner 3 surrounds and faces the bottom annular section 41 of the flexible diaphragm 4. An inner wall surface of the bottom annular section 31 of the plastic liner 3 protrudes inwardly to form an annular protrusion 311, and the longitudinal section of the annular protrusion 311 is inwardly convex. An outer wall surface of the bottom annular section 31 of the plastic liner 3 is recessed inwardly to form an annular recess 312, and the longitudinal section of the annular recess 312 is inwardly concave. The annular recess 412 of the flexible diaphragm 4 receives the annular protrusion 311 of the plastic liner 3, and the two are tightly abutted against each other.

[0026] The outer metal ring 6 surrounds the bottom annular section 31 of the plastic liner 3, and an inner wall surface of the outer metal ring 6 protrudes inwardly to form an annular protrusion 61, the longitudinal section of the annular protrusion 61 is inwardly convex. An outer wall surface of the outer metal ring 6 is recessed inwardly to form an annular recess 62, the longitudinal section of the annular recess 62 is inwardly concave. The annular recess 312 of the plastic liner 3 receives the annular protrusion 61 of the outer metal ring 6, and the two are tightly abutted against each other.

[0027] A bottom annular section 12 of the upper barrel 1 surrounds and faces the outer metal ring 6. Preferably, the bottom annular section 12 of the upper barrel 1 protrudes inwardly to form an annular protrusion 121, and the longitudinal section of the annular protrusion 121 is inwardly convex. The annular recess 62 of the outer metal ring 6 receives the annular protrusion 121 of the upper barrel 1, and the two are tightly abutted against each other. The annular protrusion 121 is not an essential feature and may be omitted.

[0028] The outer diameter of the outer metal ring 6 is smaller than the inner diameter of the bottom annular section 12 of the upper barrel 1. The inner diameter of the outer metal ring 6 is greater than the outer diameter of the bottom annular section 31 of the plastic liner 3, greater than the outer diameter of the bottom annular section 41 of the flexible diaphragm 4, and greater than the outer diameter of the inner metal ring 5.

[0029] It should also be noted that the bottom annular section 12 of the upper barrel 1 was originally flat, and only after being inwardly rolled by a roller along the circumference did it form the annular recess 120 and the annular protrusion 121 as shown in FIG. 3. The outer metal ring 6 was also originally flat; its annular protrusion 61 and annular recess 62 were likewise formed by a rolling operation with the roller. The annular protrusion 311 and annular recess 312 of the plastic liner 3, as well as the annular recess 412 of the flexible diaphragm 4, were also formed in this way —that is, they were formed together. As for the annular recess 51 of the inner metal ring 5, it was originally formed in a concave shape to receive the pre-existing convex annular protrusion 411.

[0030] Subsequent to the aforementioned rolling operation, the outer metal ring 6 and the inner metal ring 5 will tightly clamp the bottom annular section 31 of the plastic liner 3 and the bottom annular section 41 of the flexible diaphragm 4. Alternatively, the bottom annular section 12 of the upper barrel 1 and the inner metal ring 5 will tightly clamp the outer metal ring 6, the bottom annular section 31 of the plastic liner 3, and the bottom annular section 41 of the flexible diaphragm 4.

[0031] As shown in FIGS. 2 and 4, a water storage compartment S1 is formed between the plastic liner 3 and the flexible diaphragm 4, and an air storage compartment S2 is formed between the flexible diaphragm 4 and the lower barrel 2. The water or other liquid (such as oil used in hydraulic systems) inside the water storage compartment S1 can only enter and exit through the connector 11 and will not leak into the air storage compartment S2 through the bottom annular sections 31 and 41, because these sections are tightly clamped together by the inner metal ring 5 and the outer metal ring 6.

[0032] Furthermore, since the outer metal ring 6 is clamped between the bottom annular section 31 of the plastic liner 3 and the bottom annular section 12 of the upper barrel 1, a gap 32 is formed between the plastic liner 3 and the upper barrel 1. The internal pressure within the gap 32 is the same as the internal pressure within the air storage compartment S2.

[0033] When high-pressure water enters and is stored in the water storage compartment S1 via the connector 11, the internal pressure of the water storage compartment S1 will increase, thereby compressing the air within the air storage compartment S2 through the flexible diaphragm 4, making the internal pressure within both the air storage compartment S2 and the gap 32 increase to the level to the same as that of the internal pressure of the water storage compartment S1. At this time, even if the aforementioned internal pressure of the metal vessel 100 is greater than the external pressure outside the metal vessel 100, the aforementioned internal pressure merely pushes the meal vessel 100 outward, possibly causing deformation at certain portions (e.g., at the bottom annular section 2 or nearby areas), but not affecting the structure between the plastic liner 3, the flexible diaphragm 4, the inner metal ring 5, and the outer metal ring 6, since all these components are subjected to the same internal pressure and are not pushed outward by the aforementioned internal pressure. This means that the bottom annular section 31 of the plastic liner 3 and the bottom annular section 41 of the flexible diaphragm 4 are still tightly clamped by the inner metal ring 5 and the outer metal ring 6, thereby maintaining a sealed state. This ensures that the liquid within the water storage compartment S1 does not leak into the air storage compartment S2, thus, effectively resolving the internal leakage issues associated with conventional expansion tanks.

[0034] In this embodiment, it is preferable that the width W1 of the outer metal ring 6 is greater than the width W2 of the inner metal ring 5. More preferably, as shown in FIGS. 1 and 4, the outer metal ring 6 further includes an upper sheet 63 extending upward from its annular protrusion 61 (or the annular recess 62), and a lower sheet 64 extending downward from the annular protrusion 61 (or the annular recess 62). The inner and outer wall surfaces of the upper sheet 63 closely abut the plastic liner 3 and the upper barrel 1 respectively, same as the inner and outer wall surfaces of the lower sheet 64. Therefore, the upper and lower sheets 63 and 64 provide stable support for the bottom annular section 31 of the plastic liner 3, the bottom annular section 41 of the flexible diaphragm 4, and the inner metal ring 5, thereby reinforcing the structural robustness of the expansion tank at this juncture.

Examples

Embodiment Construction

[0022]FIGS. 1 to 3 illustrate an embodiment of the expansion tank according to the present invention. The expansion tank includes an upper barrel 1, a lower barrel 2, a connector 11 secured to the upper barrel 1, an inflation valve 21 secured to the lower barrel 2, a plastic liner 3 disposed inside the upper barrel 1, a flexible diaphragm 4 disposed within the plastic liner 3, an inner metal ring 5 disposed inside the flexible diaphragm 4, and an outer metal ring 6 disposed between the plastic liner 3 and the upper barrel 1. In this embodiment, both the upper barrel 1 and the lower barrel 2 are made of metal sheet material (e.g. iron plate) and after being joined end-to-end and welded together, form a metal vessel 100, but not limited as such. The inflation valve 21 is preferably threadedly engaged to the bottom of the lower barrel2, but not limited. The plastic liner 3 is made of a non-foamed plastic material and may be made of polypropylene (PP), polyethylene (PE), or other plasti...

FIELD OF INVENTION

[0001] The present invention relates to an expansion tank, particularly, to an expansion tank capable of preventing internal leakage.RELATED PRIOR ART

[0002] Expansion tanks are widely used in water piping systems to balance water pressure. Expansion tanks are also commonly connected to water treatment devices, such as reverse osmosis water purifiers, for storing the purified water produced by such devices. In addition, expansion tanks are also used in hydraulic systems.

[0003] FIGS. 5 and 6 illustrate the structure of a conventional expansion tank. In this structure, a lower end portion 931 of a rubber flexible diaphragm 93 and a lower end portion 941 of a plastic liner 94 are tightly clamped between a lower end portion 911 of a metal vessel 91 and a metal ring 92, forming a variable-volume water storage chamber 95 between the rubber flexible diaphragm 93 and the plastic liner 94, and a variable-volume air storage chamber 96 between the lower half of the metal vessel 91 and the rubber flexible diaphragm 93. The water storage chamber 95 communicates with a connector 97, which is connected to the aforementioned water piping system or reverse osmosis water purifier, allowing water to enter and exit the water storage chamber 95 through the connector 97. The air storage chamber 96 communicates with an inflation valve (not shown in the figures), through which air may be introduced into or released from the air storage chamber 96.

[0004] Under normal conditions, because the lower end portion 931 of the rubber flexible diaphragm 93 and the lower end portion 941 of the plastic liner 94 are tightly clamped between the lower end portion 911 of the metal tank 91 and the metal ring 92, the lower end portion 941 of the plastic liner 94 should closely abut the lower end portion 931 of the rubber flexible diaphragm 93. Therefore, water in the water storage chamber 95 is not expected to leak into the air storage chamber 96. However, in practice, the internal leakage issue that the water from the water storage chamber 95 leaks into the air chamber 96, still occurs. This issue of internal leakage is not uncommon and remains an urgent problem to be addressed.SUMMARY OF INVENTION

[0005] According to the applicant's research, as shown in FIG. 7, when water with high-pressure flows from a pipeline into the water storage chamber via the connector and is stored therein, the internal pressure of the water storage chamber increases. This pressure compresses the air in the air storage chamber by the rubber flexible diaphragm, thereby increasing the internal pressure of the air storage chamber to a level equal to that of the water storage chamber. At this time, the pressure within the water storage chamber continues to exert force on the plastic liner and the metal tank, which is in contact with the plastic liner. The pressure inside the air chamber likewise continues to exert force on the metal tank. When the internal pressure described above exceeds the external pressure outside the metal tank, the metal tank is pushed outward and deformed due to the internal pressure, causing deformation of the lower end portion of the metal tank as well. Consequently, a gap forms between the lower end portion of the plastic liner and the lower end portion of the rubber flexible diaphragm. As a result, water in the water storage chamber may be forced through this gap into the air chamber, thereby leading to the aforementioned internal leakage issue.

[0006] To address the aforementioned problem of internal leakage, the present invention provides an expansion tank, comprising a metal vessel including an upper barrel and a lower barrel, a plastic liner disposed inside the upper barrel of the metal vessel, a flexible diaphragm disposed inside the plastic liner, an inner metal ring disposed inside the flexible diaphragm, and an outer metal ring disposed between the upper barrel and the plastic liner, wherein a bottom annular section of the flexible diaphragm and a bottom annular section of the plastic liner are disposed between the inner metal ring and the outer metal ring while the inner and outer metal rings clamp the bottom annular section of the flexible diaphragm and the bottom annular section of the plastic liner.

[0007] In one embodiment, the inner metal ring of the expansion tank closely abuts an inner wall surface of the bottom annular section of the flexible diaphragm, an outer wall surface of the bottom annular section of the flexible diaphragm closely abuts an inner wall surface of the bottom annular section of the plastic liner, and an outer wall surface of the bottom annular section of the plastic liner closely abuts an inner wall surface of the outer metal ring, forming a water storage compartment between the flexible diaphragm and the plastic liner, and an air storage compartment between the flexible diaphragm and the lower barrel, and the water storage compartment and the air storage compartment are not in communication.

[0008] In one embodiment, an outer wall surface of the outer metal ring of the expansion tank closely abuts a bottom annular section of the upper barrel.

[0009] In another embodiment, the inner metal ring of the expansion tank is inwardly recessed to form an annular recess, the inner wall surface of the bottom annular section of the flexible diaphragm protrudes inwardly to form an annular protrusion, the annular recess of the inner metal ring receives the annular protrusion of the flexible diaphragm, and the two are tightly abutted against each other.

[0010] In one embodiment, the outer wall surface of the bottom annular section of the flexible diaphragm of the expansion tank is inwardly recessed to form an annular recess, the inner wall surface of the bottom annular section of the plastic liner protrudes inwardly to form an annular protrusion, the annular recess of the flexible diaphragm receives the annular protrusion of the plastic liner, and the two are tightly abutted against each other.

[0011] In another embodiment, the outer wall surface of the bottom annular section of the plastic liner of the expansion tank is inwardly recessed to form an annular recess, the inner wall surface of the outer metal ring protrudes inwardly to form an annular protrusion, the annular recess of the plastic liner receives the annular protrusion of the outer metal ring, and the two are tightly abutted against each other.

[0012] In yet another embodiment, the outer wall surface of the outer metal ring of the expansion tank is inwardly recessed to form an annular recess, a bottom annular section of the upper barrel protrudes inwardly to form an annular protrusion, the annular recess of the outer metal ring receives the annular protrusion of the upper barrel, and the two are tightly abutted against each other.

[0013] In one embodiment, a longitudinal section of the annular recess of the inner metal ring of the expansion tank is inwardly concave, while a longitudinal section of the annular protrusion of the flexible diaphragm is inwardly convex, and a longitudinal section of the flexible diaphragm is inwardly concave, while a longitudinal section of the annular protrusion of the plastic liner is inwardly convex, and a longitudinal section of the plastic liner is inwardly concave, a longitudinal section of the annular protrusion of the outer metal ring is inwardly convex, a longitudinal section of the outer metal is inwardly concave, a longitudinal section of the annular protrusion of the upper barrel is inwardly convex.

[0014] In another embodiment, the width of the outer metal ring of the expansion tank is greater than the width of the inner metal ring.

[0015] In one embodiment, the outer mental ring further includes an upper sheet extending upward from its annular protrusion and a lower sheet extending downward from the annular protrusion.BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1 is an exploded view of an expansion tank in accordance with the preferred embodiment of the invention.

[0017] FIG. 2 is a cross-section of the preferred embodiment of the present invention.

[0018] FIG. 3 and FIG. 4 are partial cross-sectional views of the preferred embodiment of the present invention near the inner metal ring 5.

[0019] FIG. 5 shows a cross-sectional view of a conventional expansion tank in an empty state.

[0020] FIG. 6 is an enlarged partial cross-sectional view of FIG. 5.

[0021] FIG. 7 is a cross-sectional view of a conventional expansion tank in a filled state.DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

[0022] FIGS. 1 to 3 illustrate an embodiment of the expansion tank according to the present invention. The expansion tank includes an upper barrel 1, a lower barrel 2, a connector 11 secured to the upper barrel 1, an inflation valve 21 secured to the lower barrel 2, a plastic liner 3 disposed inside the upper barrel 1, a flexible diaphragm 4 disposed within the plastic liner 3, an inner metal ring 5 disposed inside the flexible diaphragm 4, and an outer metal ring 6 disposed between the plastic liner 3 and the upper barrel 1. In this embodiment, both the upper barrel 1 and the lower barrel 2 are made of metal sheet material (e.g. iron plate) and after being joined end-to-end and welded together, form a metal vessel 100, but not limited as such. The inflation valve 21 is preferably threadedly engaged to the bottom of the lower barrel2, but not limited. The plastic liner 3 is made of a non-foamed plastic material and may be made of polypropylene (PP), polyethylene (PE), or other plastic materials. The flexible diaphragm 4 is preferably made of rubber or silicone, but not limited. Both the inner metal ring 5 and the outer metal ring 6 are made of metal sheet material (e.g. iron sheet).

[0023] As shown in FIGS. 1 and 2, the plastic liner 3 has a figure similar to and slightly smaller than that of the upper barrel 1. In this embodiment, the connector 11 is preferably made of stainless steel and is welded to a top portion of the upper barrel 1. An end portion 111 of the connector 11 extends through the upper barrel 1 and is inserted into a through hole 33 of the plastic liner 3. After the end portion 111 is riveted, it is tightly pressed against a top region of the plastic liner 3 while the top region surrounds the through hole 33. Although not explicitly shown in the Figures, in this embodiment, a metal washer and an O-ring are tightly clamped between the end portion 111 and the top region of the plastic liner 3. Additionally, a rubber gasket for preventing water leakage is also tightly clamped between the plastic liner 3 and the upper barrel 1.

[0024] As shown in FIG. 3, the inner metal ring 5 is inwardly recessed to form an annular recess 51, and the longitudinal section of the annular recess 51 is inwardly concave. A bottom annular section 41 of the flexible diaphragm 4 surrounds and faces the inner metal ring 5. An inner wall surface of the bottom annular section 41 of the flexible diaphragm 4 protrudes inwardly to form an annular protrusion 411, and the longitudinal section of the annular protrusion411 is inwardly convex. An outer wall surface of the bottom annular section 41 of the flexible diaphragm 4 is inwardly recessed to form an annular recess 412, and the longitudinal section of the annular recess 412 is inwardly concave. The annular recess 51 of the inner metal ring 5 receives the annular protrusion 411 of the flexible diaphragm 4, and the two are tightly abutted against each other.

[0025] A bottom annular section 31 of the plastic liner 3 surrounds and faces the bottom annular section 41 of the flexible diaphragm 4. An inner wall surface of the bottom annular section 31 of the plastic liner 3 protrudes inwardly to form an annular protrusion 311, and the longitudinal section of the annular protrusion 311 is inwardly convex. An outer wall surface of the bottom annular section 31 of the plastic liner 3 is recessed inwardly to form an annular recess 312, and the longitudinal section of the annular recess 312 is inwardly concave. The annular recess 412 of the flexible diaphragm 4 receives the annular protrusion 311 of the plastic liner 3, and the two are tightly abutted against each other.

[0026] The outer metal ring 6 surrounds the bottom annular section 31 of the plastic liner 3, and an inner wall surface of the outer metal ring 6 protrudes inwardly to form an annular protrusion 61, the longitudinal section of the annular protrusion 61 is inwardly convex. An outer wall surface of the outer metal ring 6 is recessed inwardly to form an annular recess 62, the longitudinal section of the annular recess 62 is inwardly concave. The annular recess 312 of the plastic liner 3 receives the annular protrusion 61 of the outer metal ring 6, and the two are tightly abutted against each other.

[0027] A bottom annular section 12 of the upper barrel 1 surrounds and faces the outer metal ring 6. Preferably, the bottom annular section 12 of the upper barrel 1 protrudes inwardly to form an annular protrusion 121, and the longitudinal section of the annular protrusion 121 is inwardly convex. The annular recess 62 of the outer metal ring 6 receives the annular protrusion 121 of the upper barrel 1, and the two are tightly abutted against each other. The annular protrusion 121 is not an essential feature and may be omitted.

[0028] The outer diameter of the outer metal ring 6 is smaller than the inner diameter of the bottom annular section 12 of the upper barrel 1. The inner diameter of the outer metal ring 6 is greater than the outer diameter of the bottom annular section 31 of the plastic liner 3, greater than the outer diameter of the bottom annular section 41 of the flexible diaphragm 4, and greater than the outer diameter of the inner metal ring 5.

[0029] It should also be noted that the bottom annular section 12 of the upper barrel 1 was originally flat, and only after being inwardly rolled by a roller along the circumference did it form the annular recess 120 and the annular protrusion 121 as shown in FIG. 3. The outer metal ring 6 was also originally flat; its annular protrusion 61 and annular recess 62 were likewise formed by a rolling operation with the roller. The annular protrusion 311 and annular recess 312 of the plastic liner 3, as well as the annular recess 412 of the flexible diaphragm 4, were also formed in this way —that is, they were formed together. As for the annular recess 51 of the inner metal ring 5, it was originally formed in a concave shape to receive the pre-existing convex annular protrusion 411.

[0030] Subsequent to the aforementioned rolling operation, the outer metal ring 6 and the inner metal ring 5 will tightly clamp the bottom annular section 31 of the plastic liner 3 and the bottom annular section 41 of the flexible diaphragm 4. Alternatively, the bottom annular section 12 of the upper barrel 1 and the inner metal ring 5 will tightly clamp the outer metal ring 6, the bottom annular section 31 of the plastic liner 3, and the bottom annular section 41 of the flexible diaphragm 4.

[0031] As shown in FIGS. 2 and 4, a water storage compartment S1 is formed between the plastic liner 3 and the flexible diaphragm 4, and an air storage compartment S2 is formed between the flexible diaphragm 4 and the lower barrel 2. The water or other liquid (such as oil used in hydraulic systems) inside the water storage compartment S1 can only enter and exit through the connector 11 and will not leak into the air storage compartment S2 through the bottom annular sections 31 and 41, because these sections are tightly clamped together by the inner metal ring 5 and the outer metal ring 6.

[0032] Furthermore, since the outer metal ring 6 is clamped between the bottom annular section 31 of the plastic liner 3 and the bottom annular section 12 of the upper barrel 1, a gap 32 is formed between the plastic liner 3 and the upper barrel 1. The internal pressure within the gap 32 is the same as the internal pressure within the air storage compartment S2.

[0033] When high-pressure water enters and is stored in the water storage compartment S1 via the connector 11, the internal pressure of the water storage compartment S1 will increase, thereby compressing the air within the air storage compartment S2 through the flexible diaphragm 4, making the internal pressure within both the air storage compartment S2 and the gap 32 increase to the level to the same as that of the internal pressure of the water storage compartment S1. At this time, even if the aforementioned internal pressure of the metal vessel 100 is greater than the external pressure outside the metal vessel 100, the aforementioned internal pressure merely pushes the meal vessel 100 outward, possibly causing deformation at certain portions (e.g., at the bottom annular section 2 or nearby areas), but not affecting the structure between the plastic liner 3, the flexible diaphragm 4, the inner metal ring 5, and the outer metal ring 6, since all these components are subjected to the same internal pressure and are not pushed outward by the aforementioned internal pressure. This means that the bottom annular section 31 of the plastic liner 3 and the bottom annular section 41 of the flexible diaphragm 4 are still tightly clamped by the inner metal ring 5 and the outer metal ring 6, thereby maintaining a sealed state. This ensures that the liquid within the water storage compartment S1 does not leak into the air storage compartment S2, thus, effectively resolving the internal leakage issues associated with conventional expansion tanks.

[0034] In this embodiment, it is preferable that the width W1 of the outer metal ring 6 is greater than the width W2 of the inner metal ring 5. More preferably, as shown in FIGS. 1 and 4, the outer metal ring 6 further includes an upper sheet 63 extending upward from its annular protrusion 61 (or the annular recess 62), and a lower sheet 64 extending downward from the annular protrusion 61 (or the annular recess 62). The inner and outer wall surfaces of the upper sheet 63 closely abut the plastic liner 3 and the upper barrel 1 respectively, same as the inner and outer wall surfaces of the lower sheet 64. Therefore, the upper and lower sheets 63 and 64 provide stable support for the bottom annular section 31 of the plastic liner 3, the bottom annular section 41 of the flexible diaphragm 4, and the inner metal ring 5, thereby reinforcing the structural robustness of the expansion tank at this juncture.

Examples

Embodiment Construction

[0022]FIGS. 1 to 3 illustrate an embodiment of the expansion tank according to the present invention. The expansion tank includes an upper barrel 1, a lower barrel 2, a connector 11 secured to the upper barrel 1, an inflation valve 21 secured to the lower barrel 2, a plastic liner 3 disposed inside the upper barrel 1, a flexible diaphragm 4 disposed within the plastic liner 3, an inner metal ring 5 disposed inside the flexible diaphragm 4, and an outer metal ring 6 disposed between the plastic liner 3 and the upper barrel 1. In this embodiment, both the upper barrel 1 and the lower barrel 2 are made of metal sheet material (e.g. iron plate) and after being joined end-to-end and welded together, form a metal vessel 100, but not limited as such. The inflation valve 21 is preferably threadedly engaged to the bottom of the lower barrel2, but not limited. The plastic liner 3 is made of a non-foamed plastic material and may be made of polypropylene (PP), polyethylene (PE), or other plasti...

Claims

1. An expansion tank, comprising:a metal vessel including an upper barrel and a lower barrel;a plastic liner disposed inside the upper barrel of the metal vessel;a flexible diaphragm disposed inside the plastic liner;an inner metal ring disposed inside the flexible diaphragm; andan outer metal ring disposed between the upper barrel and the plastic liner;wherein a bottom annular section of the flexible diaphragm and a bottom annular section of the plastic liner are disposed between the inner metal ring and the outer metal ring while the inner and outer metal rings clamp the bottom annular section of the flexible diaphragm and the bottom annular section of the plastic liner.

2. The expansion tank of claim 1, wherein the inner metal ring closely abuts an inner wall surface of the bottom annular section of the flexible diaphragm, an outer wall surface of the bottom annular section of the flexible diaphragm closely abuts an inner wall surface of the bottom annular section of the plastic liner, and an outer wall surface of the bottom annular section of the plastic liner closely abuts an inner wall surface of the outer metal ring, forming a water storage compartment between the flexible diaphragm and the plastic liner and an air storage compartment between the flexible diaphragm and the lower barrel while the water storage compartment and the air storage compartment are not in communication.

3. The expansion tank of claim 2, wherein an outer wall surface of the outer metal ring closely abuts a bottom annular section of the upper barrel.

4. The expansion tank of claim 2, wherein the inner metal ring is inwardly recessed to form an annular recess, the inner wall surface of the bottom annular section of the flexible diaphragm protrudes inwardly to form an annular protrusion, the annular recess of the inner metal ring receives the annular protrusion of the flexible diaphragm, and the two are tightly abutted against each other.

5. The expansion tank of claim 4, wherein the outer wall surface of the bottom annular section of the flexible diaphragm is inwardly recessed to form an annular recess, the inner wall surface of the bottom annular section of the plastic liner protrudes inwardly to form an annular protrusion, the annular recess of the flexible diaphragm receives the annular protrusion of the plastic liner, and the two are tightly abutted against each other.

6. The expansion tank of claim 5, wherein the outer wall surface of the bottom annular section of the plastic liner is inwardly recessed to form an annular recess, the inner wall surface of the outer metal ring protrudes inwardly to form an annular protrusion, the annular recess of the plastic liner receives the annular protrusion of the outer metal ring, and the two are tightly abutted against each other.

7. The expansion tank of claim 6, wherein the outer wall surface of the outer metal ring is inwardly recessed to form an annular recess, a bottom annular section of the upper barrel protrudes inwardly to form an annular protrusion, the annular recess of the outer metal ring receives the annular protrusion of the upper barrel, and the two are tightly abutted against each other.

8. The expansion tank of claim 7, wherein a longitudinal section of the annular recess of the inner metal ring is inwardly concave, a longitudinal section of the annular protrusion of the flexible diaphragm is inwardly convex, a longitudinal section of the flexible diaphragm is inwardly concave, a longitudinal section of the annular protrusion of the plastic liner is inwardly convex, a longitudinal section of the plastic liner is inwardly concave, a longitudinal section of the annular protrusion of the outer metal ring is inwardly convex, a longitudinal section of the outer metal is inwardly concave, a longitudinal section of the annular protrusion of the upper barrel is inwardly convex.

9. The expansion tank of claim 1, wherein the width of the outer metal ring is greater than the width of the inner metal ring.

10. The expansion tank of claim 6, the outer mental ring further includes an upper sheet extending upward from its annular protrusion and a lower sheet extending downward from the annular protrusion.

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