water heater

Abstract

To provide a water heater comprising a joint capable of restraining a decrease in strength even if using a recycled material.SOLUTION: A water heater comprises a tank for storing a heat medium, a heat pump unit for heating the heat medium stored in the tank, a pipe connected to the tank, and a joint 70 provided in a branch part of the pipe, and made of synthetic resin. The joint 70 comprises a pipe part 71 to which a feedwater temperature sensor 12 is connected, a flange part 72 formed so as to protrude from the pipe part 71, and a rib 75 connecting an outer peripheral surface of the pipe part 71 and the flange part 72.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a water heater. [Background technology]

[0002] In recent years, there have been proposals to effectively utilize waste materials as resources, for example, by using recycled materials for resin parts. Patent Document 1 describes a water heater in which a flange portion is formed on a pipe joint for connecting pipes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 008056 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the pipe joint described in Patent Document 1, if the content ratio of recycled material is increased too much, although it is advantageous in terms of cost, there is a problem in that the strength decreases. [Means for solving the problem]

[0005] The water heater of the present invention comprises a tank for storing a heat medium, a heating means for heating the heat medium stored in the tank, a pipe connected to the tank, and a joint made of synthetic resin provided at a branching portion of the pipe, the joint comprising a pipe portion to which a pipe or device is connected, a flange portion formed to protrude from the pipe portion, and a rib connecting an outer peripheral surface of the pipe portion and the flange portion. The rib and the O-ring provided inside the pipe portion are formed at positions where they do not overlap in the radial direction. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is an overall configuration diagram of a water heater according to an embodiment of the present invention; [Figure 2] FIG. 2 is a perspective view showing the joint of the present embodiment. [Figure 3] FIG. 2 is a front view showing the joint of the present embodiment. [Figure 4] FIG. 2 is a plan view showing the joint of the present embodiment. [Figure 5] FIG. 2 is a side view showing the joint of the present embodiment. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 4. [Figure 7] FIG. 10 is a perspective view showing a state in which a temperature sensor and the like are attached to a joint. [Figure 8] FIG. 1 is a perspective view of a quick fastener. [Figure 9] FIG. 2 is a plan view of the quick fastener. [Figure 10] FIG. 2 is a side view of the quick fastener. [Figure 11] FIG. 8 is an enlarged side view of a main part of FIG. 7. [Figure 12] FIG. 8 is an enlarged cross-sectional view of a main part of FIG. 7. [Figure 13] 10 is a graph showing the relationship between the recycled material usage rate and the allowable load. [Figure 14] This is a distribution diagram of the leakage occurrence rate when virgin material and 50% recycled material are used. [Figure 15] FIG. 10 is an explanatory diagram for determining an equation for the crushing rate. [Figure 16] 10 is a graph showing variations in sealing rate when the groove diameter is changed. [Figure 17] 10 is another graph showing variations in the sealing rate when the groove diameter is changed. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, modes for carrying out the present invention (hereinafter referred to as "embodiments") will be described in detail with reference to the drawings as appropriate. FIG. 1 is a diagram showing the overall configuration of a water heater according to an embodiment of the present invention. As shown in FIG. 1, the water heater 1 includes a hot water storage tank unit 2 and a heat pump unit 3 (heating means).

[0008] The hot water storage tank unit 2 includes a tank 10 that stores hot water (heat medium), a general hot water supply circuit 20 (hot water supply circuit), and a bathtub hot water supply circuit 30 (hot water supply circuit). The hot water storage tank unit 2 is configured such that the tank 10 is housed in a rectangular box-shaped case (not shown) with the tank 10 covered with a heat insulating material, and pipes and valves that make up the general hot water supply circuit 20 and the bathtub hot water supply circuit 30 are arranged in the gap between the inner wall of the case and the tank 10. The tank 10 is also provided with temperature sensors 11a, 11b, 11c, 11d, 11e, and 11f that detect the temperature of the hot water stored in the tank 10.

[0009] The heat pump unit 3 is a well-known one and is configured to include a compressor (not shown) that compresses a refrigerant (e.g., carbon dioxide) to a high temperature and high pressure, a water-refrigerant heat exchanger 3a that condenses the refrigerant from the compressor and heats it by heat exchange with water from the tank 10, an expansion valve (not shown) that expands the refrigerant from the water-refrigerant heat exchanger 3a, and an evaporator (not shown) that absorbs heat from the atmosphere and evaporates the expanded refrigerant.

[0010] The heat pump unit 3 has a heat medium inlet connected to the bottom of the tank 10 via a heat pump supply pipe 4, and a heat medium outlet connected to the top of the tank 10 via a heat pump return pipe 5. The heat pump unit 3 is also provided with a circulation pump 3b that circulates the heat medium inside the tank 10 between the tank 10 and the heat pump unit 3. The heat pump supply pipe 4 is connected to a heat pump return pipe 5 via a pipe 6, and a three-way valve 7 is provided at the connection between the heat pump supply pipe 4 and the pipe 6.

[0011] The hot water storage tank unit 2 also includes a hot water supply pipe 40 that takes out high-temperature water from the top of the tank 10 and returns it to the bottom of the tank 10 via a hot water supply heat exchanger 41 (hot water heat exchanger). The hot water supply pipe 40 is provided with, in order from the upstream side, the hot water supply heat exchanger 41, a hot water supply circulation pump 42, and check valves 43 and 44. Between the top of the tank 10 and the hot water supply heat exchanger 41, the hot water supply pipe 40 is also branched off and connected to a pipe 46 that is equipped with a relief valve 45 that maintains the pressure inside the tank 10 at a predetermined pressure.

[0012] A water supply pipe 50 connected to a water supply source (tap water) is connected to the bottom of tank 10. This water supply pipe 50 is provided with, in order from the upstream side, a strainer 51, a check valve 52, a pressure reducing valve 53, and a check valve 54. A water supply temperature sensor 12 is provided in water supply pipe 50 between check valve 52 and pressure reducing valve 53. Water supply pipe 50 branches between water supply temperature sensor 12 and pressure reducing valve 53 and is provided with water supply pipe 55 which branches off between water supply temperature sensor 12 and pressure reducing valve 53 and is connected to an inlet on the secondary side (the side receiving heat) of hot water supply heat exchanger 41.

[0013] The general hot water supply circuit 20 supplies hot water to general hot water terminals such as faucets and showers in kitchens, washrooms, bathrooms, etc., and refers to a usage pattern in which the supplied hot water is used once and then completed. The general hot water supply circuit 20 is of a direct water pressure type that supplies tap water from a water supply pipe 50 to the general hot water terminal without reducing the pressure with a pressure reducing valve, and is equipped with a hot water supply pipe 21 connected to an outlet on the secondary side (the side that receives heat) of a hot water supply heat exchanger 41. An accumulator 22 is provided in this hot water supply pipe 21, and a hot water supply temperature sensor 13 and a hot water supply flow rate sensor 14 are provided between the hot water supply heat exchanger 41 and the accumulator 22.

[0014] The hot water heat exchanger 41 heats tap water (low temperature water) supplied from the water supply pipe 50 by exchanging heat with high temperature water taken out from the top of the tank 10. The high temperature water that has been heat exchanged in the hot water heat exchanger 41 has its temperature reduced and returns to the inside of the tank 10 from the bottom.

[0015] The hot water circulation pump 42 controls (increases or decreases) the rotation speed of the motor of the hot water circulation pump 42 so that the hot water temperature becomes the hot water temperature set by the main remote controller 4a, based on the hot water temperature detected by the hot water temperature sensor 13. The hot water flow rate sensor 14 detects that hot water supply has started from the general hot water supply terminal.

[0016] The bathtub hot water supply circuit 30 includes a bath filling circuit 31 for filling bathtub B with hot water and a reheating circuit 32 for reheating bathwater stored in bathtub B. The bath filling circuit 31 includes a bath piping 33, one end of which is connected to one end of the bathtub B's adapter and the other end of which is connected to the hot water supply pipe 40 between the tank 10 and the hot water heat exchanger 41. The bath piping 33 is equipped with bath mixing valves 35 and 34, a bath solenoid valve 36, and other components, arranged in this order from upstream to downstream during bath filling. The bath piping 33 is also equipped with a bath return temperature sensor 33a, a water level sensor 33b, and a water flow switch 33d, arranged in this order from upstream to downstream. The bath mixing valve 34 controls the mixing ratio of high-temperature water from the tank 10 and water (low-temperature water) from the water supply pipe 55 that has been depressurized by the pressure reducing valve 53, thereby maintaining the bath temperature set by the bath remote control 4b. In addition, a check valve 37 is provided in the water supply pipe 55. The bath mixing valve 35 controls the mixing ratio of high-temperature water from the tank 10 and hot water (e.g., medium-temperature water) taken out from an intermediate take-out pipe 38 connected to the middle of the tank 10.

[0017] The reheating circuit 32 has one end of pipe 39a connected to the inlet of the reheating heat exchanger 39 and one end of pipe 39b connected to the outlet. The other end of pipe 39a is connected to a circulation adjustment valve 39c. The reheating heat exchanger 39 is configured as a coil and is disposed at the top of the tank 10. It exchanges heat between the bath water flowing through the reheating heat exchanger 39 and the hot water (high-temperature water) in the tank 10. The opening of the circulation adjustment valve 39c is adjusted to adjust the flow rate to the pipe 39d side (the side bypassing the reheating heat exchanger 39) and the flow rate to the reheating heat exchanger 39 side. The inlet port of the circulation adjustment valve 39c is connected via pipe 39e between the bath solenoid valve 36 of the bath pipe 33 and the bath return temperature sensor 33a. A bath circulation pump 39f is also provided in pipe 39e, which discharges bath water toward the circulation adjustment valve 39c. The other end of the pipe 39b is connected to a pipe 39d. A reheating temperature sensor 39g is provided on the pipe 39b.

[0018] The control device 100 is composed of a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), an input / output interface, and other components. It receives various operation signals from the main remote control 4a and bath remote control 4b, the tank temperature (detected value) detected by each temperature sensor 11a-11f, the temperatures (detected values) detected by the water supply temperature sensor 12 (device), the hot water supply temperature sensor 13, the bath return temperature sensor 33a, and the reheating temperature sensor 39g, the flow rates (detected values) from the hot water supply flow sensor 14 and the bath flow sensor, an ON signal from the water flow switch 33d, and the water level in the bathtub B from the water level sensor 33b. The control device 100 also controls the bath mixing valves 34 and 35, the bath solenoid valve 36, the circulation adjustment valve 39c, the hot water supply circulation pump 42, and the bath circulation pump 39f. The control device 101 of the heat pump unit 3 is communicatively connected to the control device 100 of the hot water storage tank unit 2. For example, when a command to perform boiling operation is received from the control device 100, the control device 101 controls the compressor, the blower fan, and the circulation pump 3b based on a temperature sensor (not shown) that measures the temperature of water flowing from the tank 10 into the water-refrigerant heat exchanger 3a, a temperature sensor (not shown) that measures the temperature of hot water flowing from the water-refrigerant heat exchanger 3a into the tank 10, and a temperature sensor (not shown) that measures the outside air temperature, to perform an operation to boil the water in the tank 10.

[0019] In the water heater 1 configured as described above, multiple pipes are connected to the tank 10 and the heat pump unit 3. For this reason, joints are required at branching points where the flow paths branch off and at parts where devices such as temperature sensors (supply water temperature sensor 12, hot water temperature sensor 13, bath return temperature sensor 33a, reheating temperature sensor 39g, etc.) are installed in the flow paths. For example, the branching point circled by a dashed line in FIG. 1 is provided with a joint 70 to which the supply water temperature sensor 12 is connected. The joint 70 installed in this part will be described below as an example.

[0020] Fig. 2 is a perspective view showing a joint made of synthetic resin containing recycled material of this embodiment, Fig. 3 is a front view showing the joint of this embodiment, Fig. 4 is a plan view showing the joint of this embodiment, Fig. 5 is a side view showing the joint of this embodiment, and Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 4. Details of the recycled material will be explained later. As shown in FIG. 2, the joint 70 includes a pipe section 71 to which, for example, the water supply temperature sensor 12, the hot water supply temperature sensor 13, the bath return temperature sensor 33a, the reheating temperature sensor 39g, etc. (device, see FIG. 1) are connected, and a flange section 72 formed to protrude outward from the pipe section 71. The pipe section 71 is formed at a branch section P of the pipe section 73. The pipe section 73 corresponds, for example, to the water supply pipe 50 shown in FIG. 1. The pipe section 73 is formed with a pipe section 74 extending in a direction perpendicular to the axial direction of the pipe section 73. The end of the pipe section 73 and one end of the pipe section 74 are connected midway through the water supply pipe 50. The other end of the pipe section 74 is connected to a pipe (water supply pipe 55) connected to an inlet on the secondary side (the side receiving heat) of the hot water supply heat exchanger 41.

[0021] The joint 70 is made of a resin material such as polyphenylene sulfide (hereinafter referred to as PPS). Specifically, from the perspective of efficient resource utilization, the joint 70 is made by mixing virgin PPS material (made from new materials) with recycled PPS material. Note that the material of the joint 70 is not limited to PPS, and it may be made of other resins such as polyphenylene ether (PPE).

[0022] As shown in Figure 3, a joint 70 made of synthetic resin containing recycled materials has a rib 75 formed on the underside (backside) of a flange portion 72. This rib 75 is formed at a position that overlaps with the radial center of the pipe portion 71 when viewed from the front (side). The rib 75 is also formed to be shorter than the axial length of the pipe portion 71. The thickness of the rib 75 is also formed to be thinner than the thickness of the flanges 74a, 74b at both ends of the pipe portion 74.

[0023] 4, the diameter R1 of the flange portion 72 is formed to be substantially the same as the outer diameter R2 of the pipe portion 73. In addition, the diameter R1 of the flange portion 72 is formed to be smaller than the outer diameter R3 of the flange 74a provided on the pipe portion 74.

[0024] As shown in Figure 5, a joint 70 made of synthetic resin containing recycled materials has ribs 75, 75 formed to connect the outer peripheral surface of a pipe portion 71 and a flange portion 72. The ribs 75 are formed to protrude from the rear surface of the flange portion 72 and the outer peripheral surface of the pipe portion 71. The ribs 75 have a right-angled triangular shape when viewed from the side in Figure 5. The ribs 75 are positioned symmetrically with respect to the radial center of the pipe portion 71. The shape of the ribs 75 is not limited to a linear triangular shape, and they may be curved or asymmetric with respect to the radial center of the pipe portion 71.

[0025] Furthermore, flange portion 72 is positioned so as not to protrude outward from a straight line S connecting the end of pipe portion 74 (the side where pipe portion 71 is formed) and the end (tip) of pipe portion 73. This reduces the risk of flange portion 72 cracking when fitting 70 made of synthetic resin containing recycled materials is dropped.

[0026] As shown in Figure 6, a joint 70 made of synthetic resin containing recycled material is formed with a through hole 71s for attaching, for example, a feedwater temperature sensor 12 (see Figure 1) or the like. This through hole 71s communicates with the flow path of a pipe section 73. Furthermore, through hole 71s has a large diameter hole 71a on the flange section 72 side and a hole 71b on the pipe section 73 side that is smaller in diameter than hole 71a.

[0027] The ribs 75 are formed so as to protrude from the lower surface (rear surface) of the flange portion 72 and also from the outer peripheral surface of the pipe portion 71. The ribs 75 are formed integrally with the pipe portion 71 and the flange portion 72 by resin molding.

[0028] FIG. 7 is a perspective view showing a state in which, for example, a feedwater temperature sensor 12 or the like is attached to a joint made of synthetic resin containing recycled materials. As shown in Figure 7, when attaching, for example, a feedwater temperature sensor 12 or the like to the joint 70, the feedwater temperature sensor 12 or the like is inserted into the pipe section 71 (see Figure 6) to a predetermined position. After attachment, a metal quick fastener 80 is used to hold the feedwater temperature sensor 12 or the like so that it does not come out of the joint 70. This quick fastener 80 is attached to the joint 70 by inserting it from the end side of the pipe section 73 toward the pipe section 74.

[0029] FIG. 8 is a perspective view of the quick fastener, FIG. 9 is a plan view of the quick fastener, and FIG. 10 is a side view of the quick fastener. As shown in Figure 8, the quick fastener 80 includes a holding portion 81 that sandwiches and holds the outer peripheral surface of the pipe portion 71 (see Figure 7), and a holding portion 82 that sandwiches and holds, for example, the feedwater temperature sensor 12. A gap 83 is formed between the holding portion 81 and the holding portion 82, through which the flange portion 72 is inserted.

[0030] 9, the holding portion 81 is formed with a curved portion 81a that abuts against the outer peripheral surface of the pipe portion 71 (see FIG. 2). The inner diameter R10 of this holding portion 81 (inner diameter of the abutting portion) is smaller than the outer diameter R20 (outer diameter of the pipe portion) of the pipe portion 71 (see FIG. 5). This allows the force with which the holding portion 81 holds the pipe portion 71 to be strengthened.

[0031] The quick fastener 80 has a tip 81s formed at one end of the holding portion 81 and shaped like a V-shape. The quick fastener 80 has a tip 82s formed at one end (tip) of the holding portion 82 and shaped like a V-shape. The quick fastener 80 also has bases 81t, 82t formed on the opposite side of the tip portions 81s, 82s and having a substantially rectangular space in a plan view. In FIG. 9, the holding portion 82 is located on the front side in the direction perpendicular to the paper surface, and the holding portion 81 is located on the back side. The rectangular space of the base 82t is wider than that of the base 81t. The base 81t shown in FIG. 9 is shaped to overlap with the base 82t in the axial direction (direction perpendicular to the paper surface).

[0032] 10, a gap 83 into which the flange portion 72 fits is formed between the holding portion 81 and the holding portion 82. The base portion 81t and the base portion 82t are configured to be connected at their ends.

[0033] When attaching the quick fastener 80 configured in this manner to a synthetic resin joint 70 manufactured from recycled material and equipped with a feedwater temperature sensor 12 or the like, for example, first, the tip 81s is pressed against the pipe 71 so that the side of the pipe 71 faces the tip 81s and the side of the feedwater temperature sensor 12 or the like faces the tip 82s, and then the tip 81s is pressed against the pipe 71, and the tip 82s is pressed against the feedwater temperature sensor 12 or the like. This causes the tip 81s to bend and expand, and the pipe 71 is inserted up to the retaining portion 81. The tip 82s is also bent and expanded, and the feedwater temperature sensor 12 or the like is inserted up to the retaining portion 82.

[0034] The pair of ribs 75 (see FIG. 5) are arranged on a straight line and in opposite directions across the pipe portion 71. Therefore, one rib 75 is inserted from the tip portion 81s through the holding portion 81 to the base portion 81t, and the other rib 75 is inserted up to the position of the tip portion 81s.

[0035] 11 is an enlarged side view of the essential part of FIG. 7, and FIG. 12 is an enlarged cross-sectional view of the essential part of FIG. 11, when the quick fastener 80 is attached to the pipe section 71 equipped with the feed water temperature sensor 12, for example, the pipe section 71 is held by the holding section 81, and the feed water temperature sensor 12, etc. are held by the holding section 82. In addition, the flange section 72 is inserted into the gap 83 between the holding sections 81 and 82.

[0036] As shown in Figure 12, for example, the water supply temperature sensor 12 has a held portion 12a held by the holding portion 82, a first body portion 12b that fits into the hole 71a of the pipe portion 71, and a second body portion 12c that is formed with a smaller diameter than the first body portion 12b and fits into the hole 71b.

[0037] Additionally, first body 12b is formed to be shorter than the axial length of hole 71a. As a result, an O-ring 90 is provided in the gap formed between second body 12c and hole 71a. This seals the gap between feedwater temperature sensor 12 and the pipe 71, preventing water from leaking through pipe 71 to the outside of joint 70, which is made of synthetic resin and contains recycled materials.

[0038] Furthermore, the ribs 75, 75 are positioned axially offset from the O-ring 90. In other words, the rib 75 and the O-ring 90 are positioned so that they do not overlap in the radial direction. As shown in FIG. 12 , the O-ring 90 is positioned on the opposite side of the rib 75 (below the line L shown at the bottom of the rib 75) from the line L. This is because, if the fitting 70, including the rib 75, is molded from a synthetic resin containing recycled material, the resin at the position of the rib 75 is pulled, causing many sink marks on the inner wall surface of the hole 71a (the area surrounded by the dashed line P1). Therefore, if an O-ring is placed at the position of the rib 75, sealing may not be possible. Therefore, the rib 75 and the O-ring 90 are offset in the axial direction of the pipe portion 71 so that the rib 75 and the O-ring 90 do not overlap in the radial direction.

[0039] Furthermore, when the hot water supply terminal (faucet) is closed, a so-called water hammer may apply pressure to, for example, the water supply temperature sensor 12, pushing the quick fastener 80 upward in the illustration, which could cause the retaining portion 81 of the quick fastener 80 to collide with the underside of the flange portion 72. Therefore, as shown in FIG. 11 , a buffer material 91 is provided between the retaining portion 81 of the quick fastener 80 and the flange portion 72 to prevent direct contact between the quick fastener 80 and the fitting 70 made of a synthetic resin containing recycled materials. This prevents the retaining portion 81 from directly colliding with the flange portion 72, thereby reducing the risk of the flange portion 72 cracking. The buffer material 91 may be vinyl tape attached to the underside of the flange portion 72, or an elastic material such as rubber may be provided.

[0040] In the above embodiment, an example was given of connecting the pipe portion 71 to the feedwater temperature sensor 12, etc., but the same configuration can be used to connect pipe portions. In this case, since force is applied to the flange portion of one pipe portion and the flange portion of the other pipe portion, the risk of the flange portions cracking can be reduced by providing a cushioning material to each flange portion.

[0041] Figure 13 is a graph showing the relationship between the recycled material usage rate and allowable load. Note that Figure 13 shows the case where PPS is used as the recycled material. The test to determine the allowable load (breaking load) is carried out using a compression testing machine by applying a load until cracks appear in the flange portion. It is known that mixing recycled materials with virgin materials weakens the impact strength compared to virgin materials. Furthermore, the pipe joints used in the water heater 1 are formed with flanges as receiving parts for the quick fasteners 80. The following aims to maximize the use of recycled materials to obtain joints with strength equivalent to that of virgin materials.

[0042] As shown in Figure 13, the allowable load (impact strength) decreases as the recycled content (%) increases. Specifically, when the recycled content is 0% (100% virgin material), the allowable load is 92.5 kg. When the recycled content is 25%, the allowable load is 91.9 kg, and when it is 50%, the allowable load is 87.5 kg. When the recycled content is 100%, the allowable load is 74.9 kg. Thus, when the recycled content is between 0 and 50%, the allowable load only decreases to 5.4%, whereas when the recycled content is between 50 and 100%, it drops sharply to 14.4%. Thus, when the recycled content is up to 50% (50% or less), the strength reduction rate can be kept within 5.4%.

[0043] Figure 14 shows the distribution of leakage rates when virgin material and recycled material are used at 50%. Figure 15 is an explanatory diagram for determining the crushing rate formula. The piping of a water heater is made up of multiple components (joints), and the connections are sealed with O-rings or other seals to prevent water leakage. Sealing performance is affected by the sealing rate and surface roughness of the connections, but resin fittings 70 manufactured using injection molding containing recycled materials tend to have varying surface roughness between individual molded products. Furthermore, recycled materials tend to have a rough surface because they contain a large amount of crushed glass filler. Poor sealing performance increases the probability of water heater leaks, making it necessary to improve and manage sealing performance to improve yield.

[0044] In addition, the surface that the O-ring contacts must meet a certain standard for surface roughness. Virgin and recycled materials have different surface roughness values. In other words, recycled materials have a rougher surface than virgin materials. This is because the glass filler contained in recycled materials such as PPS is crushed, resulting in a lower surface roughness compared to virgin materials. The smaller the Rz, which indicates surface roughness, the better the surface roughness. As shown in Figure 14, virgin materials (0% recycled material) have a surface roughness of 3.0 at best, while materials containing 50% recycled material have a surface roughness of 6.0. The higher the leak rate, the greater the risk of leakage. Note that an Rz value above 6.0 does not necessarily mean leakage; rather, it simply means that the leak rate increases due to variations in the O-ring's thickness, outer diameter, inner diameter, and other individual components. Therefore, in this embodiment, taking into consideration that the use of recycled material will result in a worsening of surface roughness, the sealing rate of the O-ring is increased to deal with leakage even when many sink marks occur on the inner wall surface of the hole 71a of the fitting 70 made of synthetic resin containing recycled material.

[0045] As shown in FIG. 15, the crushing rate E (sealing rate) can be expressed by the following formula. E = (σ / W) × 100(%) σ is the compression allowance, which can be calculated using WH. W is the thickness of the O-ring, and H is the groove depth. The higher the compression rate E, the lower the risk of leakage, but it is generally said that a sealing rate of 8 to 30% is required.

[0046] FIG. 16 is a graph showing the variation in sealing rate when the groove diameter is changed, and FIG. 17 is another graph showing the variation in sealing rate when the groove diameter is changed. Note that the groove diameter is the diameter of the annular groove that contacts the inner diameter side of the O-ring. FIG. 16 shows the cases of P10A to P22, with the digits indicating the groove diameter. FIG. 17 shows the cases of P2 to P10, with the numbers indicating the groove diameter. For example, for P10, the median groove diameter is Φ10. For P10A to P22, the O-ring wire diameter is 2.4 mm, and for P2 to P10, the O-ring wire diameter is 1.9 mm.

[0047] As shown in Figure 16, the median groove diameter is for virgin material, and in that case, the seal rate falls within the range of 8 to 30%. Furthermore, when the groove diameter is +0.1 from the median, the seal rate falls within the range of 8 to 30%. Furthermore, when the groove diameter is +0.2 from the median, the seal rate falls within the range of 8 to 30%. Furthermore, when the groove diameter is +0.3 from the median, the upper limit of the seal rate exceeds 30%.

[0048] The matrix on the right side of the graph in Figure 16 shows the yield (leakage rate) according to surface roughness. As shown, if the median seal rate is 16% and is within the range of 8 to 30%, a surface roughness of Rz 3.0 results in a good yield. Note that if the median seal rate is 16% and the surface roughness is 6.0, the yield will be average, and if the surface roughness is 9.0, the yield will be poor.

[0049] In addition, when using 50% recycled material, by setting the groove diameter to the median + 0.2 when the surface roughness is 6.0, the median seal rate can be 21%, and it can be within the range of 8 to 30%, resulting in a good yield. Furthermore, when the median seal material is 21% and the surface roughness is 9.0, the yield is normal, and when the surface roughness is 12.0, the yield is poor.

[0050] As shown in Figure 17, for P2 to P10, the median seal rate is originally high. Therefore, for a surface roughness of 6.0, by increasing the groove diameter by 0.1 from the median, the median seal rate becomes 23%, and the seal rate can be kept within the range of 8 to 30%, resulting in a good yield. Note that when the median seal rate is 23% and the surface roughness is 9.0, the yield becomes normal, and when the surface roughness is 12.0, the yield becomes poor.

[0051] In this way, the groove diameter was set so that the seal portion of the water heater fitting 70, which uses recycled material (50% or less), has the same sealing performance as virgin material and an appropriate sealing rate for each diameter. While the surface roughness of virgin material is easily controlled at Rz 3.0 or higher, mixing 50% recycled material reduces the surface roughness to Rz 6.0. For example, in the case of a typical P16 fitting, the O-ring groove diameter is Φ16, resulting in a sealing rate of 16%. Therefore, when recycled material is used, the groove diameter can be increased from Φ16 to Φ16.2, improving the sealing rate to 21%, achieving a sealing rate equivalent to that of virgin material.

[0052] As described above, the water heater 1 of this embodiment includes a tank 10 that stores hot water (heat medium), a heat pump unit 3 that heats the hot water stored in the tank 10, a water supply pipe 50 connected to the tank 10, and a synthetic resin joint 70 provided at a branch point P of the water supply pipe 50. The joint 70 includes a pipe section 71 to which a water supply temperature sensor 12 and other devices (devices) are connected, a flange section 72 that protrudes from the pipe section 71, and a rib 75 that connects the outer circumferential surface of the pipe section 71 to the flange section 72. This allows the strength of the joint 70 to be equivalent to that of a joint made of virgin material, even when a joint 70 manufactured using recycled materials is used. Furthermore, the use of recycled materials reduces the manufacturing cost of the joint 70.

[0053] In this embodiment, the rib 75 and the O-ring 90 provided inside the pipe portion 71 are formed in positions where they do not overlap in the radial direction. This makes it difficult for sink marks to form in the recycled material at the position of the pipe portion 71 where the O-ring 90 is located, and therefore the sealing performance of the O-ring 90 is not impaired.

[0054] In addition, in this embodiment, the ribs 75 are formed symmetrically across the center of the pipe portion 71. This prevents the attachment of the quick fastener 80 from being impaired.

[0055] Furthermore, in this embodiment, a buffer material 91 is provided between the flange portion 72 and the quick fastener 80. This makes it possible to prevent the quick fastener 80 from directly colliding with the flange portion 72 due to the pressure generated during water hammering, thereby reducing the risk of the flange portion 72 cracking.

[0056] In addition, in this embodiment, the outer diameter R20 of the tubular portion 71 is larger than the inner diameter R10 of the retaining portion 81 (abutting portion) that abuts against and holds the tubular portion 71 of the quick fastener 80. This allows the retaining portion 81 to firmly hold the tubular portion 71, reducing the risk of the quick fastener 80 colliding with the flange portion 72.

[0057] Furthermore, in this embodiment, the joint 70 is made of a resin material such as polyphenylene sulfide (PPS) or polyphenylene ether (PPE), and the proportion of recycled PPS or PPE in the joint 70 is 50% or less of the entire joint 70. This makes it possible to obtain a joint 70 that does not have a significant decrease in strength compared to joints made only from virgin PPS or PPE material. [Explanation of symbols]

[0058] 1. Water heater 2 Hot water tank unit 3 Heat pump unit (heating means) 10 Tank 12 Water supply temperature sensor (device) 50 Water supply pipe (piping) 70 Joints 71 Pipe section 72 Flange 75 Ribs 80 Quick Fastener 81 Holding part (contact part) 82 Holding part 83 Gap 90 O-rings 91 Cushioning material R10 Inner diameter (inner diameter of contact part) R20 outer diameter (outer diameter of pipe)

Claims

1. a tank for storing a heat medium; a heating means for heating the heat medium stored in the tank; a pipe connected to the tank; a synthetic resin joint provided at a branching portion of the pipe, The joint includes a pipe portion to which a pipe or a device is connected, a flange portion formed to protrude from the pipe portion, and a rib connecting an outer peripheral surface of the pipe portion and the flange portion, The rib and the O-ring provided in the pipe portion are positioned so as not to overlap in the radial direction.

2. The water heater according to claim 1, The ribs are formed symmetrically with respect to the center of the pipe portion.

3. In the water heater according to claim 2, A water heater in which a buffer material is provided between the flange portion and the quick fastener.

4. In the water heater according to claim 3, A water heater in which the outer diameter of the pipe portion is larger than the inner diameter of the abutment portion of the quick fastener that abuts against the pipe portion.

5. In the water heater according to claim 1, the joint is made of a resin material such as polyphenylene sulfide (PPS) or polyphenylene ether (PPE), The joints of the water heater contain 50% or less of the recycled PPS or PPE material.

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