Pipe sealing structure and water heater

Abstract

To improve workability of press-fitting work for press-fitting a backup ring to a press-fitting part.SOLUTION: A pipe seal structure 50 comprises a first pipe, and a second pipe fitted to an outer peripheral side of an end part of the first pipe. The end part of the first pipe is constituted so as to include a cylindrical part 53, and a backup ring 51 fitted to an outer peripheral side of the cylindrical part 53. The cylindrical part 53 comprises: a guide part 54 having an outside diameter D1 smaller than an inside diameter D3 of the backup ring 51; a press-fitting part 55 provided continuously with the guide part 54, and having an outside diameter D2 equal to or slightly larger than the inside diameter D3 of the backup ring 51; and a seal fitting part 57 provided continuously with the press-fitting part 55, and constituting a seal surface 58 together with an end surface 56 of the backup ring 51.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a pipe sealing structure and a water heater.

Background Art

[0002] As a pipe sealing structure in a water heater, for example, a water heater described in Japanese Unexamined Patent Application Publication No. 2020-8217 (hereinafter referred to as Patent Document 1) is known. This water heater includes a heat exchanger, a water supply pipe connected to the heat exchanger, a hot water outlet pipe connected to the heat exchanger, and a return pipe connected to the water supply pipe. By connecting the hot water outlet pipe and the return pipe with an external pipe, the hot water discharged from the hot water outlet pipe returns to the return pipe through the external pipe, and a circulation path from the water supply pipe to the heat exchanger is formed. The return pipe includes a circulation pump and a horizontal pipe fitted on the inner peripheral side of the discharge pipe of the circulation pump.

[0003] A groove for mounting an O-ring is formed at the upstream end of the horizontal pipe. Since the groove is formed over the entire circumference of the horizontal pipe, if the horizontal pipe is integrally formed, a parting line will occur on the sealing surface of the groove, deteriorating the sealing performance. Therefore, if one wall surface of the groove is configured as a separate component by a backup ring and this backup ring is attached to the pipe body to form the horizontal pipe, although it is necessary to add a slide type, the parting line can be prevented from occurring on the sealing surface.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in order to attach the backup ring to the pipe body, it is necessary to press-fit the backup ring into the pipe body to prevent it from falling off. Some allowance is necessary for press-fitting, but if the allowance is too large, press-fitting will become difficult. Also, if the resin material that makes up the horizontal pipe is soft, the resin may be scraped off and adhere to the sealing surface, which may impair the sealing performance. [Means for solving the problem]

[0006] The pipe seal structure of the present disclosure comprises a first pipe and a second pipe fitted to the outer circumference of the end of the first pipe, wherein the end of the first pipe is configured to include a cylindrical portion and a backup ring fitted to the outer circumference of the cylindrical portion, and the cylindrical portion has a guide portion having an outer diameter smaller than the inner diameter of the backup ring, a press-fit portion connected to the guide portion and having an outer diameter the same as or slightly larger than the inner diameter of the backup ring, and a seal mounting portion connected to the press-fit portion and forming a seal surface together with the end face of the backup ring. [Effects of the Invention]

[0007] According to this disclosure, the workability of the press-fitting operation in which the backup ring is pressed into the press-fitting section can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a front view of a water heater with an instant hot water function, with the front cover removed. [Figure 2] Figure 2 is a schematic diagram of the instant hot water system. [Figure 3] Figure 3 is a front view of the circulation path forming unit. [Figure 4] Figure 4 is a cross-sectional view showing the internal structure of the pipe sealing structure. [Figure 5] Figure 5 is a front view showing the connection structure between the return pipe and the intermediate pipe. [Figure 6] Figure 6 is a plan view showing the connection structure between the return pipe and the intermediate pipe. [Figure 7] Figure 7 is a cross-sectional view of AA in Figure 6. [Figure 8] Figure 8 is a cross-sectional view of Figure 7, showing the state before the backup ring is pressed into the press-fit section. [Modes for carrying out the invention]

[0009] [Description of Embodiments in this Disclosure] First, the embodiments of this disclosure will be listed and described. (1) The pipe seal structure of the present disclosure comprises a first pipe and a second pipe fitted to the outer circumference of the end of the first pipe, wherein the end of the first pipe is configured to include a cylindrical portion and a backup ring fitted to the outer circumference of the cylindrical portion, and the cylindrical portion has a guide portion having an outer diameter smaller than the inner diameter of the backup ring, a press-fit portion connected to the guide portion and having an outer diameter the same as or slightly larger than the inner diameter of the backup ring, and a seal mounting portion connected to the press-fit portion and forming a seal surface together with the end face of the backup ring.

[0010] Because the outer diameter of the guide section is smaller than the inner diameter of the backup ring, it becomes easier to fit the backup ring onto the outer circumference of the guide section, and the guide section stabilizes the backup ring. Since the backup ring is pressed into the press-fit section in a stable state, the work efficiency of the press-fitting operation is improved.

[0011] (2) Preferably, the guide portion has a tapered surface whose outer diameter increases as it approaches the press-fit portion. Because the guide section has a tapered surface, the backup ring can smoothly transition from the tapered surface of the guide section to the press-fit section, preventing the inner surface of the backup ring from being worn down.

[0012] (3) The water heater of the present disclosure comprises a burner unit and a heat exchanger, a water supply pipe connected to the heat exchanger, a hot water outlet pipe connected to the heat exchanger, and a return pipe connected to the water supply pipe, wherein the hot water outlet pipe and the return pipe are connected by external piping so that the hot water discharged from the hot water outlet pipe returns to the return pipe via the external piping, and a circulation path from the water supply pipe to the heat exchanger is formed, wherein the return pipe comprises a circulation pump having a second pipe and a first pipe fitted to the inner circumference side of the second pipe of the circulation pump, the end of the first pipe is configured to include a cylindrical portion and a backup ring fitted to the outer circumference side of the cylindrical portion, the cylindrical portion having a guide portion having an outer diameter smaller than the inner diameter of the backup ring, a press-fit portion provided in connection with the guide portion and having an outer diameter the same as or slightly larger than the inner diameter of the backup ring, and a seal mounting portion provided in connection with the press-fit portion and forming a sealing surface together with the end face of the backup ring, the water heater.

[0013] (4) Preferably, the guide portion has a tapered surface whose outer diameter increases as it moves from the hot water inlet end toward the press-fit portion.

[0014] [Details of the embodiments of this disclosure] Embodiments of the present disclosure are described below. The present disclosure is not limited to these examples, but is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are intended. <Embodiment> Embodiments of this disclosure will be described with reference to Figures 1 to 8. In the following description, the vertical and horizontal directions are based on the directions indicated by arrows in each figure.

[0015] [Overall structure of a water heater] FIG. 1 is a front view showing an example of an instant hot water supply device with an instant hot water function (hereinafter simply referred to as "hot water supply device") 1, and FIG. 2 is a schematic diagram of an instant hot water system. This hot water supply device 1 has a housing 2 composed of a box body 3 that closes five sides except the front surface, and a front cover (not shown) that closes the front surface of the box body 3. Inside the housing 2, a combustion device 5 including a burner unit 6, a heat exchanger 7, and an exhaust hood 8 is installed from below, and an exhaust pipe 9 provided at the upper end of the exhaust hood 8 penetrates the upper plate of the box body 3 and protrudes upward. Mounting brackets 10, 10 for installation on an indoor wall or the like are provided above and below the back surface of the box body 3, and a plurality of air supply ports (not shown) are formed on the back plate of the box body 3.

[0016] On the bottom surface of the box body 3, a tubular gas connection port 12 to which an external gas pipe is connected, a tubular water supply connection port 13 to which an external water supply pipe is connected, a tubular hot water supply connection port 14 and a tubular return connection port 15 to which an external hot water supply pipe is connected, are provided.

[0017] The burner unit 6 includes a plurality of burners not shown inside, to which the gas connection port 12 is connected to supply fuel gas to the burners, and a gas pipe 16 equipped with a main valve, a proportional control valve, etc. not shown is connected, and a fan 17 for supplying combustion air to the burners is provided.

[0018] As shown in FIG. 2, the heat exchanger 7 has a heat transfer pipe 18 that penetrates a plurality of fins in a meandering shape. A water supply pipe 19 connected to the water supply connection port 13 is connected to the inlet end of the heat transfer pipe 18, and a hot water outlet pipe 20 connected to the hot water supply connection port 14 is connected to the outlet end of the heat transfer pipe 18.

[0019] A return pipe 21 is connected between the return connection port 15 and the water supply pipe 19. As shown in Figure 3, this return pipe 21 consists of a tubular return connection port 15, a circulation pump 22 to which a downward-facing suction pipe 22a is connected to the return connection port 15, a horizontal pipe 23 to which the upstream end is connected to the horizontal discharge pipe 22b of the circulation pump 22, and a branch pipe section 25 which is connected to the downstream end of the horizontal pipe 23 and is formed by branching horizontally from a relay pipe 24 that forms part of the water supply pipe 19. The ends of each pipe are connected to each other with clips 26, 26..., forming the return pipe 21 that connects the return connection port 15 to the relay pipe 24. The upper and lower ends of the relay pipe 24 are also connected with clips 26, respectively.

[0020] Furthermore, the horizontal pipe 23 is provided with a downward-facing branch pipe 27. The lower end of this branch pipe 27 is connected to the bottom plate of the box body 3, with the lower end open to the outside. A plug 28 is screwed into and fixed to the lower end from below, allowing the lower end to be opened at will.

[0021] Furthermore, as shown in Figure 4, a check valve 29 is provided at the downstream end of the horizontal pipe 23 to prevent backflow of water from the water supply pipe 19 to the circulation pump 22.

[0022] The horizontal pipe 23 and the branch pipe 27 are integrally formed, and a check valve 29 is incorporated into the horizontal pipe 23 to form a T-shaped unit, making it easy to install and remove from the water heater. In particular, the intermediate pipe 24 is also installed separately as part of the water supply pipe 19, so by incorporating the circulation pump 22, the T-shaped boiler (horizontal pipe 23 and branch pipe 27 with check valve 29), and the intermediate pipe 24 as a circulation path forming unit U into an existing water heater, an instant hot water function can be easily added.

[0023] As shown in Figure 1, the water heater 1 includes a controller 4 that receives detection signals from various thermistors and sensors and operates various valves to control the water temperature, and a remote control (not shown) that is connected to the controller 4 for communication. The controller 4 is installed on the underside of the burner unit 6. The controller 4 is configured, for example, as a known microcomputer, and is configured to acquire signals from various sensors provided on the water heater 1, and to control various actuators provided on the water heater 1.

[0024] Figure 2 shows a schematic of the instant hot water system 40 using the water heater 1, with configurations other than those related to the circulation path omitted. 30 is a bypass pipe that connects the water supply pipe 19 and the hot water outlet pipe 20, bypassing the heat exchanger 7.

[0025] This instant hot water system 40 is constructed by connecting an external piping 41 equipped with multiple hot water taps 42, 42... between the hot water supply connection port 14 and the return connection port 15. This creates a circulation path in which the hot water supplied from the outlet pipe 20 returns to the return pipe 21 through the external piping 41 and then returns to the heat exchanger 7 via the water supply pipe 19. Therefore, by operating the circulation pump 22 to circulate the hot water within the circulation path and burning the burner in the burner unit 6, it becomes possible to maintain the temperature set by the controller 4. In other words, instant hot water is available by opening any of the hot water taps 42.

[0026] [Pipe sealing structure using backup rings] Next, the pipe sealing structure 50 using the backup ring 51 will be described with reference to Figures 4 to 8. As shown in Figure 4, the pipe sealing structure 50 comprises a horizontal pipe 23, a discharge pipe 22b of a circulation pump 22, and a sealing ring 52 that seals the space between them. The upstream end of the horizontal pipe 23 is configured to include a cylindrical portion 53 and a cylindrical backup ring 51 that fits onto the outer circumference of the cylindrical portion 53.

[0027] As shown in Figure 8, the cylindrical portion 53 includes a guide portion 54 having an outer diameter D1 smaller than the inner diameter D3 of the backup ring 51, a press-fit portion 55 connected to the downstream end of the guide portion 54 (the end on the check valve 29 side) and having an outer diameter D2 that is the same as or slightly larger than the inner diameter D3 of the backup ring 51, and a seal mounting portion 57 connected to the downstream end of the press-fit portion 55 (the end on the check valve 29 side) and forming a seal surface 58 together with the end face 56 of the backup ring 51. A groove is formed by the end face 56 of the backup ring and the bottom and side surfaces of the seal mounting portion 57 to mount the seal ring 52 by surrounding it from three sides.

[0028] The guide portion 54 has a tapered surface T that is inclined such that its outer diameter D1 increases as it approaches the press-fit portion 55 from the hot water inlet. The downstream end of the guide portion 54 has the same outer diameter as the upstream end (the end on the guide portion 54 side) of the press-fit portion 55. The press-fit portion 55 is formed such that its outer diameter D2 remains constant from the downstream end of the guide portion 54 to the seal mounting portion 57. The inclination angle of the tapered surface T of the guide portion 54 with respect to the outer circumferential surface of the press-fit portion 55 is set to less than 45 degrees. The dimension of the guide portion 54 in the press-fit direction is longer than the dimension of the press-fit portion 55 in the press-fit direction (e.g., 1 mm or more). Therefore, the backup ring 51 can be naturally inserted into the guide portion 54, and the position and orientation of the backup ring 51 at the start of press-fitting are stable.

[0029] The seal mounting portion 57 is formed to be slightly larger than the outer diameter D2 of the press-fit portion 55, and a step 59 is formed between the press-fit portion 55 and the seal mounting portion 57. When the backup ring 51 is pressed into the press-fit portion 55, as shown in Figure 7, the end face 56 of the backup ring 51 comes into contact with the step 59, stopping its movement in the press-fit direction, and the press-fitting operation is completed. As a result, the backup ring 51 is attached to the cylindrical portion 53.

[0030] When the backup ring 51 is mounted on the cylindrical portion 53, the upstream end of the backup ring 51 (the end opposite to the end face 56) and the upstream end of the guide portion 54 (the end opposite to the check valve 29) are aligned in the radial direction of the horizontal pipe 23. In addition, the outer circumferential surface of the backup ring 51 and the outer circumferential surface of the horizontal pipe 23 are aligned in the axial direction of the horizontal pipe 23.

[0031] The guide section 54 corrects the tilt of the backup ring 51 when it is attached to the cylindrical section 53, guiding it to a position perpendicular to the direction of press-fitting into the press-fit section 55. This ensures that the press-fitting operation into the press-fit section 55 is performed in a stable position and makes the press-fitting operation easier, improving work efficiency. Furthermore, it prevents the backup ring 51 from being forcibly pressed in while in a tilted position, which could result in the backup ring 51 or a part of the press-fit section 55 being scraped off during press-fitting and adhering to the sealing surface 58, thereby compromising the sealing performance.

[0032] When the horizontal pipe 23, with the backup ring 51 attached to the cylindrical portion 53, is fitted to the inner circumference of the discharge pipe 22b of the circulation pump 22, the seal ring 52 is sandwiched between the inner surface of the discharge pipe 22b and the seal surface 58, as shown in Figure 4. This seals the space between the discharge pipe 22b and the horizontal pipe 23. Here, since the seal mounting portion 57 is open in the axial direction of the horizontal pipe 23 (opposite direction to the check valve 29) before the backup ring 51 is attached, the seal mounting portion 57 can be formed by cutting out the slide mold for forming the seal mounting portion 57 in the axial direction of the horizontal pipe 23. Therefore, no parting line is formed on the seal surface 58 of the seal mounting portion 57, and there is no risk of impairing the sealing performance.

[0033] [Effects of the Embodiment] As described above, the pipe seal structure 50 according to the embodiment is a pipe seal structure 50 comprising a horizontal pipe 23 and a discharge pipe 22b fitted to the outer circumference of the end of the horizontal pipe 23, wherein the end of the horizontal pipe 23 is configured to include a cylindrical portion 53 and a backup ring 51 fitted to the outer circumference of the cylindrical portion 53, and the cylindrical portion 53 comprises a guide portion 54 having an outer diameter D1 smaller than the inner diameter D3 of the backup ring 51, a press-fit portion 55 provided in connection with the guide portion 54 and having an outer diameter D2 the same as or slightly larger than the inner diameter D3 of the backup ring 51, and a seal mounting portion 57 provided in connection with the press-fit portion 55 and forming a seal surface 58 together with the end face 56 of the backup ring 51.

[0034] The instant-hot water heater 1 according to this embodiment comprises a burner unit 6 and a heat exchanger 7, a water supply pipe 19 connected to the heat exchanger 7, a hot water outlet pipe 20 connected to the heat exchanger 7, and a return pipe 21 connected to the water supply pipe 19. By connecting the hot water outlet pipe 20 and the return pipe 21 with an external pipe 41, the hot water discharged from the hot water outlet pipe 20 returns to the return pipe 21 via the external pipe 41, forming a circulation path from the water supply pipe 19 to the heat exchanger 7. The return pipe 21 is fitted to the inner circumference of the discharge pipe 22b of the circulation pump 22. The water heater 1 with an instant hot water function comprises a connecting horizontal pipe 23, the end of which the horizontal pipe 23 is composed of a cylindrical portion 53 and a backup ring 51 fitted to the outer circumference of the cylindrical portion 53, the cylindrical portion 53 having a guide portion 54 having an outer diameter D1 smaller than the inner diameter D3 of the backup ring 51, a press-fit portion 55 provided in connection with the guide portion 54 and having an outer diameter D2 the same as or slightly larger than the inner diameter D3 of the backup ring 51, and a seal mounting portion 57 provided in connection with the press-fit portion 55 and forming a seal surface 58 together with the end face 56 of the backup ring 51.

[0035] Since the outer diameter D1 of the guide portion 54 is smaller than the inner diameter D3 of the backup ring 51, it becomes easier to fit the backup ring 51 onto the outer circumference of the guide portion 54, and the backup ring 51 is stabilized by the guide portion 54. Because the backup ring 51 is pressed into the press-fit portion 55 in a stable state, the workability of the press-fitting operation is improved.

[0036] The guide portion 54 preferably has a tapered surface T whose outer diameter D1 increases as it moves from the hot water inlet end toward the press-fit portion 55. Because the guide portion 54 has a tapered surface T, the backup ring 51 can smoothly transition from the tapered surface T of the guide portion 54 to the press-fit portion 55, preventing the inner surface of the backup ring 51 from being worn down.

[0037] <Other Embodiments> (1) In the above embodiment, a pipe seal structure 50 between the discharge pipe 22b of the circulation pump 22 and the horizontal pipe 23 was illustrated, but the invention is not limited thereto, and may be applied, for example, to a pipe seal structure between the horizontal pipe 23 and the branch pipe section 25.

[0038] (2) In the above embodiment, a backup ring 51 that forms an annular shape when viewed from the front was illustrated, but a backup ring that forms a C shape when viewed from the front may also be used.

[0039] (3) In the above embodiment, a guide portion 54 having a tapered surface T was illustrated, but the guide portion only needs to have a smaller diameter than the press-fit portion 55 and may not have a tapered surface. Also, in the above embodiment, a tapered surface T having a straight shape in a cross-sectional view when the cylindrical portion 53 is cut in the axial direction was illustrated, but a tapered surface having a curved shape may also be used.

[0040] (4) In the above embodiment, a water heater 1 with an instant hot water function was used as an example, but the invention is not limited thereto and may also be applied to the piping sealing structure of a water heater that does not have an instant hot water function. [Explanation of Symbols]

[0041] 1: Water heater with instant hot water function 2: Housing 2A: One side panel 2B: The other side panel 3: Box body 4: Controller 5: Combustion device 6: Burner unit 7: Heat exchanger 8: Exhaust hood 9: Exhaust pipe 10: Mounting bracket 12: Gas connection port 13: Water supply connection port 14: Hot water connection port 15: Return connection port 16: Gas pipe 17: Fan 18: Heat transfer pipe 19: Water supply pipe 20: Hot water outlet pipe 21: Return pipe 22: Circulation pump 22a: Suction pipe 22b: Discharge pipe (second piping) 23: Horizontal pipe (first piping) 24: Intermediate pipe 25: Branch pipe section 26: Clip 27: Branch pipe 28: Plug 29: Check valve 30: Bypass pipe 40: Instant hot water system 41: External piping 42: Hot water tap 50: Pipe sealing structure 51: Backup ring 52: Seal ring 53: Cylindrical section 54: Guide section 55: Press-fit section 56: End face 57: Seal mounting section 58: Seal surface 59: Step D1: Outer diameter of guide section D2: Outer diameter of press-fit section D3: Inner diameter of backup ring T: Tapered surface U: Circulation path forming unit

Claims

1. A pipe seal structure comprising a first pipe and a second pipe fitted to the outer circumference of the end of the first pipe, The end of the first pipe is configured to include a cylindrical portion and a backup ring fitted to the outer circumference of the cylindrical portion. The cylindrical portion includes a guide portion having an outer diameter smaller than the inner diameter of the backup ring, a press-fit portion connected to the guide portion and having an outer diameter the same as or slightly larger than the inner diameter of the backup ring, and a seal mounting portion connected to the press-fit portion and forming a sealing surface together with the end face of the backup ring. The guide portion corrects the inclination of the backup ring when the backup ring is attached to the cylindrical portion, and guides it to a position perpendicular to the direction of press-fitting into the press-fit portion. A pipe seal structure in which the dimension of the guide portion in the press-fitting direction is longer than the dimension of the press-fitting portion in the press-fitting direction.

2. The pipe seal structure according to claim 1, wherein the guide portion has a tapered surface whose outer diameter increases towards the press-fit portion.

3. Burner unit and heat exchanger, A water supply pipe connected to the heat exchanger, A hot water outlet pipe connected to the heat exchanger, The system includes a return pipe connected to the aforementioned water supply pipe, A water heater in which the hot water outlet pipe and the return pipe are connected by external piping, so that the hot water discharged from the hot water outlet pipe returns to the return pipe via the external piping, and a circulation path is formed from the water supply pipe to the heat exchanger, The return pipe comprises a circulation pump having a second pipe and a first pipe fitted to the inner circumference of the second pipe of the circulation pump. The end of the first pipe is configured to include a cylindrical portion and a backup ring fitted to the outer circumference of the cylindrical portion. The cylindrical portion comprises a guide portion having an outer diameter smaller than the inner diameter of the backup ring, a press-fit portion connected to the guide portion and having an outer diameter the same as or slightly larger than the inner diameter of the backup ring, and a seal mounting portion connected to the press-fit portion and forming a sealing surface together with the end face of the backup ring, in a water heater.

4. The water heater according to claim 3, wherein the guide portion has a tapered surface whose outer diameter increases from the hot water inlet end toward the press-fit portion.

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