Bottom plate and hot water storage device

Abstract

A bottom plate (1) is laid on a lower part of a loaded object. The bottom plate (1) is provided with: a plurality of coupling protrusions (11) that can be coupled to the loaded object and each of which is in a protruding form in a direction perpendicular to a plate surface of the bottom plate; and an annular protrusion that is annularly disposed in an area surrounded by the coupling protrusions (11).

Description

Bottom plate and hot water storage device

[0001] The present disclosure relates to a bottom plate and a hot water storage device.

[0002] The hot water storage tank of a hot water heater is supported by a base plate. Water is stored in the hot water storage tank, and a heating device that heats the water is placed on the tank. Therefore, the load applied to the base plate is large, and the base plate must have high rigidity.

[0003] To increase rigidity, the bottom plate can be made thicker, but considering cost, workability, etc., a thinner plate is more desirable.

[0004] Patent Document 1 discloses a plate member having a plurality of ribs extending radially from the center to the periphery in order to reduce the plate thickness while maintaining the required rigidity. It is conceivable to use this plate member as the bottom plate of a hot water storage tank.

[0005] Japanese Patent Application Laid-Open No. 2006-292312

[0006] However, when this plate member is used as a bottom plate, the load from the hot water storage tank is concentrated along the ribs at the center of the bottom plate due to the radial ribs, which makes it prone to bending deformation and makes it difficult to stably support the load.

[0007] A similar problem exists with a bottom plate on which a heavy object other than the hot water storage tank is placed and which supports the object.

[0008] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a thin, highly rigid bottom plate and a hot water storage device using the same.

[0009] To achieve the above object, the present disclosure provides a bottom plate that is laid beneath a load, and includes a plurality of connecting protrusions that are connectable to the load and that are convex in a direction perpendicular to the surface of the bottom plate, and an annular protrusion that is annularly arranged in an area surrounded by the connecting protrusions.

[0010] According to the present disclosure, the bottom plate is connectable to a load and includes a plurality of connecting protrusions that are convex in a direction perpendicular to the surface of the bottom plate, and an annular protrusion that is annularly arranged in the area surrounded by the connecting protrusions. As a result, the load received by the connecting protrusions is not concentrated in the center of the bottom plate, making it less susceptible to bending deformation. This allows for a thin and highly rigid bottom plate.

[0011] (A) is a perspective view of a bottom plate according to an embodiment of the present disclosure, and (B) is a cross-sectional view taken along line A-A. (A) is a cross-sectional view taken along line A-A in FIG. 1(A), and (B) is a cross-sectional view taken along line B-B. Plan views of a bottom plate according to a modified example of the present disclosure. (A) and (B) are plan views of a bottom plate according to a modified example of the present disclosure. (A), (B), (C), and (D) are plan views of a bottom plate according to a modified example of the present disclosure, and (E) is a cross-sectional view taken along line V-V. Plan views of a bottom plate according to a modified example of the present disclosure. (A) is a diagram showing the overall structure of a heat pump hot water heater according to an embodiment, and (B) is a diagram showing a connection portion between the bottom plate and a hot water tank.

[0012] Below, the bottom plate and hot water storage device according to an embodiment of the present disclosure will be described with reference to the drawings, using as an example a hot water storage device comprising a hot water storage tank and a bottom plate that supports the load of a heat pump type hot water storage heater.

[0013] As shown in Fig. 7(A), the heat pump hot water heater 6 according to this embodiment includes a rectangular parallelepiped housing 5, a hot water storage tank 2 for storing hot water, and a heating device 4 for heating the hot water stored in the hot water storage tank 2. The hot water storage tank 2 is cylindrical overall, with the upper and lower longitudinal surfaces each having a spherically bulging, protruding shape. The hot water storage tank 2 is placed inside the housing 5 with its longitudinal axis facing up. The heating device 4 is placed on top of the hot water storage tank 2.

[0014] A bottom plate 1 is laid between the housing 5 and the hot water storage tank 2. The hot water storage tank 2 is placed on the bottom plate 1 and supports it. Hereinafter, the surface of the bottom plate 1 on which the hot water storage tank 2 is placed will be referred to as the upper surface, and the surface opposite the upper surface will be referred to as the lower surface. As shown enlarged in Figure 7(B), the bottom of the hot water storage tank 2 is covered with a heat insulating material 36, which keeps the hot water inside the hot water storage tank 2 warm. There may be some contact between the heat insulating material 36 and the bottom plate 1 due to manufacturing errors, but they generally do not come into contact.

[0015] The bottom of the hot water storage tank 2 protrudes in a curved shape. This makes it difficult to place the hot water storage tank 2 directly on the bottom plate 1. To address this, a base 31 for supporting the hot water storage tank 2 on the bottom plate 1 is fixed to the lower end of the hot water storage tank 2, for example, by welding. The hot water storage tank 2 is supported by the base 31, and the base 31 is supported by the bottom plate 1. For this reason, the bottom plate 1 is also required to have a structure that makes it easy to place the base 31 on it.

[0016] The base 31 is cylindrical and opens in the vertical direction, and the central axis of the base 31 coincides with the central axis S of the hot water storage tank 2.

[0017] 7(B), the base 31 has connecting holes HC on its side surface for connecting to the bottom plate 1. The connecting holes HC are provided in three locations at equal intervals of approximately 120° in the circumferential direction around the central axis of the base 31. The three connecting holes HC are connected to three connecting holes HA provided at equal intervals in the bottom plate 1.

[0018] As shown in FIG. 1A, the bottom plate 1 is composed of a rectangular thin plate in a plan view. From the viewpoint of stability, it is desirable that one side of the bottom plate 1 be larger than the diameter of the hot water storage tank 2. On the other hand, if it is too large, the installation space will become large. For this reason, it is desirable that one side of the bottom plate 1 be approximately 20 to 50% larger than the diameter of the hot water storage tank 2. For example, if the diameter of the hot water storage tank 2 is 450 mm, the length of one side of the bottom plate 1 is approximately 540 to 675 mm.

[0019] The bottom plate 1 is a flat metal plate with a thickness of, for example, about 1 to 2 cm, and to increase its rigidity, it has convex and concave portions formed thereon as shown in Figures 1(A) and 1(B) and 2(A) and 2(B). The convex and concave portions are formed by, for example, press working, cutting work, or the like.

[0020] The bottom plate 1 is formed by, for example, cutting or pressing a steel plate or a metal plate such as a copper alloy or an aluminum alloy, or both.

[0021] More specifically, the bottom plate 1 includes three connecting protrusions 11 to which the base 31 is connected, a peripheral protrusion 12 formed on the outer periphery, i.e., the peripheral edge, of the bottom plate 1, three arc-shaped protrusions 13 that annularly surround the center of the bottom plate 1, connecting protrusions 14 that connect both ends of each arc-shaped protrusion 13 to the peripheral protrusion 12, a central recess 15 including the center C of the arc-shaped protrusion 13, and three peripheral recesses 16 formed between the connecting protrusions 11 and the arc-shaped protrusions 13. The bottom plate 1 further includes an edge portion 17 that surrounds the edge of the bottom plate 1 and a fixing portion 18 that serves as a connection portion with the housing 5. The center C is located on the line of the central axis S of the hot water storage tank 2, but because the bottom plate 1 is not necessarily square, the center C and the center of the bottom plate 1 do not necessarily coincide.

[0022] Note that the convex portions and concave portions are relative expressions, and when the plate surface of the bottom plate 1 is used as a reference, the convex portions are those above the concave portions, i.e., those convex portions perpendicularly upward from the plate surface, and the concave portions are those recessed from the convex portions in the direction perpendicular to the plate surface. The boundary portions between the convex portions and the concave portions are inclined at approximately 45° with respect to the plate surface, taking into account formability during press working. In this embodiment, the multiple convex portions 11 to 14 have upper surfaces at the same height. Similarly, the multiple concave portions 15 and 16 have upper surfaces at the same height. Furthermore, in this embodiment, the plate thickness of each portion of the bottom plate 1 is constant.

[0023] The bottom plate 1 has a plurality of convex portions 11 to 14, a plurality of concave portions 15, 16, boundary regions between the convex portions and the concave portions, and an edge portion 17, which increases the section modulus and enhances rigidity.

[0024] Next, the configuration of each part of the bottom plate 1 will be described in order.

[0025] The connecting protrusions 11 are the parts to which the base 31 is connected, and three of them are provided at equal distances from the center C and at equal intervals of approximately 120° circumferentially, corresponding to the arrangement of the connecting holes HC formed in the base 31.

[0026] Each connecting protrusion 11 has a connecting hole HA for connecting the base 31 of the hot water storage tank 2 to the bottom plate 1. The connecting holes HA are through-holes. Three connecting holes HA are provided equidistant from the center C and at approximately 120° equal intervals in the circumferential direction, corresponding to the arrangement of the connecting holes HC formed in the base 31. Each connecting protrusion 11 is rectangular in plan view, with one side perpendicular to an imaginary line connecting the center C and the connecting hole HA and two sides parallel. The side perpendicular to the imaginary line connecting the center C and the connecting hole HA is not parallel to the sides of the bottom plate 1. The connecting protrusions 11 are arranged radially to efficiently distribute the load and suppress deformation of the center portion, which has the lowest rigidity. The connecting protrusions 11 are also sandwiched between the peripheral recesses 16. The connecting protrusions 11 correspond to the load points to which the load from the hot water storage tank 2 is applied.

[0027] The peripheral convex portion 12 surrounds the center C and is formed along each edge of the bottom plate 1. The peripheral convex portion 12 is formed continuously with the connecting convex portion 11, and the load received by the connecting convex portion 11 is also transmitted to the peripheral convex portion 12. The width W2 of the convex surface of the peripheral convex portion 12 varies depending on the position, but is, for example, about 3 to 10% of the length of one side of the bottom plate 1.

[0028] The arc-shaped protrusions 13 include three arc-shaped protrusions formed at equal distances from each other and at equal intervals of approximately 120° in the circumferential direction around the center C. The arc-shaped protrusions 13 are separated in the circumferential direction, but as a whole form a circular protrusion surrounding the center C. Each arc-shaped protrusion 13 is formed opposite the connecting protrusion 11, and the center of the arc of each arc-shaped protrusion 13 is located on an imaginary line connecting the center C and the connecting hole HA. The width W3 of the protrusion surface of each arc-shaped protrusion 13 is, for example, approximately 10 to 15% of the length of one side of the bottom plate 1.

[0029] The connecting protrusions 14 connect the arc-shaped protrusions 13 and the peripheral protrusions 12. Specifically, one end of each connecting protrusion 14 is continuous with one end of the corresponding arc-shaped arc-shaped protrusion 13, and the other end is continuous with the peripheral protrusion 12. Each connecting protrusion 14 is formed in a straight line. The connecting protrusions 14, the arc-shaped protrusions 13, and the connecting protrusions 14 that are continuous with each other are arranged at equal intervals of 120° with respect to the center C, and have a constant width. Therefore, the width W3 of the arc-shaped protrusions 13 and the width W4 of the connecting protrusions 14 are equal.

[0030] The peripheral convex portion 12, the connecting convex portion 14, the arc-shaped convex portion 13, the connecting convex portion 14 and the peripheral convex portion 12 are continuous, which prevents the load received by the connecting convex portion 11 from being transmitted to the central portion of the bottom plate 1.

[0031] The central recess 15 is a circular region including a center C, the outer edge of which is defined by the arc-shaped protrusion 13. As shown in FIG. 7A , the center C is aligned with the central axis S of the hot water storage tank 2. That is, when the hot water storage tank 2 is placed on the bottom plate 1, the arc-shaped protrusion 13 is located at the bottom center of the hot water storage tank 2. The diameter W5 of the central recess 15 is, for example, approximately 20 to 40% of the length of one side of the bottom plate 1. To increase the section modulus of the bottom plate 1 and suppress deformation, the central recess 15 is recessed relative to the connecting protrusion 11 that supports the load of the hot water storage tank 2. Furthermore, if holes are provided for piping, wiring, etc., deformation may not be sufficiently suppressed, so it is preferable not to provide holes in the central recess 15.

[0032] Radially extending extension recesses 15A are arranged connected to the central recess 15. The outer edges of the extension recesses 15A are defined by the connecting protrusions 14 and the peripheral protrusions 12, and are formed at equal intervals of approximately 120° from the center C, extending radially at a constant width. The provision of the extension recesses 15A increases the section modulus between the connecting protrusions 11, thereby suppressing deformation. In particular, this can contribute to improving the ease of installation of the heating device 4 on top of the hot water storage tank 2.

[0033] The peripheral recess 16 has an outer edge defined by the connecting protrusion 11, the peripheral edge protrusion 12, the arc-shaped protrusion 13, and the connecting protrusion 14, and is formed at equal intervals of 120° with respect to the center C. The peripheral recess 16 separates the connecting protrusion 11 from the opposing arc-shaped protrusion 13. This prevents the load received by the connecting protrusion 11 from being transmitted to the central portion of the bottom plate 1.

[0034] The edge portion 17 is a continuous plate-like body that surrounds the edge of the bottom plate 1 and is formed at right angles to the plane of the bottom plate 1. The corners of the edge portion 17 are formed seamlessly, so that when the bottom plate 1 is subjected to a load, the edge portion 17 prevents the bottom plate 1 from deforming.

[0035] The fixing portions 18 are used to secure the bottom plate 1 to the housing 5 and are formed as convex projections on the top surface at the four corners of the bottom plate 1. A connecting hole HB is formed in the center of the fixing portion 18 for connection to the housing 5. The housing 5 also has a connecting hole HF (not shown) in the lower part of the housing 5 for connection to the fixing portion 18. The position of the connecting hole HB of the fixing portion 18 overlaps the position of the connecting hole HF of the housing 5. The bottom plate 1 can be secured to the housing 5 by connecting the connecting hole HF of the housing 5 to the connecting hole HB of the fixing portion 18. Any connection method may be used, for example, using an adjuster bolt. The load of the hot water tank 2 is first transmitted to the connecting protrusions 11 and then to the lower part of the bottom plate 1 via the fixing portions 18. That is, the bottom plate 1 first bears the load of the hot water tank 2, and then the bottom of the housing 5 bears the load of the entire heat pump hot water heater 6.

[0036] Next, a method for connecting the bottom plate 1 having the above-described configuration to the hot water storage tank 2 and the housing 5 will be described with reference to FIG. 7(B).

[0037] First, a cushioning material 33A is placed on the connecting protrusion 11 to reduce impact on the connecting protrusion 11. The cushioning material 33A is square in plan view, with the lengths of its vertical and horizontal sides equal to the width W1 of the convex surface of the connecting protrusion 11. The cushioning material 33A also has a central connection hole HE for passing a bolt 34. When placing the cushioning material 33A on the connecting protrusion 11, the connection hole HA of the connecting protrusion 11 is aligned with the connection hole HE of the cushioning material 33A. Furthermore, a cushioning material 33B is placed on the peripheral recess 16 to distribute the load transferred from the base 31 to the bottom plate 1. The cushioning material 33B is taller than the cushioning material 33A and is sandwiched between the base 31 and the peripheral recess 16 when the hot water storage tank 2 is placed on the bottom plate 1. The material of the cushioning materials 33A and 33B is not limited as long as it has elasticity, and may be, for example, rubber. In order to prevent the contact surfaces of the buffer materials 33A and 33B from being displaced, an adhesive may be applied or attached to the surfaces of the buffer materials 33A and 33B.

[0038] Next, the hot water storage tank 2 and the bottom plate 1 are connected. More specifically, the hot water storage tank 2 is placed on the bottom plate 1, and the connecting hole HC of the base 31 is connected to the connecting hole HA of the connecting protrusion 11 via the L-shaped metal fitting 32. The L-shaped metal fitting 32 has a shape in which one side of two square metal plates in a plan view is connected at a right angle. The length of each side of the L-shaped metal fitting 32 is equal to the width W1 of the convex surface of the connecting protrusion 11. In addition, the L-shaped metal fitting 32 has one connecting hole HD in the center of each side for connecting to the base 31 and the bottom plate 1.

[0039] To connect the connecting hole HC of the base 31 and the L-shaped metal fitting 32, the position of the connecting hole HC of the base 31 is aligned with the position of one of the connecting holes HD of the L-shaped metal fitting 32, and they are fastened together using a bolt 34 and a nut 35. Furthermore, to connect the connecting hole HA of the connecting protrusion 11 and the L-shaped metal fitting 32, the position of the connecting hole HA of the connecting protrusion 11 is aligned with the position of the connecting hole HE of the cushioning material 33A and the position of one of the connecting holes HD of the L-shaped metal fitting 32, and they are fastened together using a bolt 34 and a nut 35. At this time, three sets of connecting holes HC and connecting holes HA are connected by the L-shaped metal fitting 32.

[0040] Next, the bottom plate 1 connected to the hot water storage tank 2 is connected to the housing 5. More specifically, the connection holes HB of the four fixing parts 18 provided on the bottom plate 1 are aligned with the connection holes HF of the housing 5 that correspond to the positions of the fixing parts 18, and each connection point is fastened using bolts and nuts.

[0041] When the bottom plate 1, hot water tank 2, and housing 5 are connected in this manner, the load point of the hot water tank 2 is located on the connecting protrusion 11, and a bending moment is generated in the bottom plate 1. At this time, the load of the hot water tank 2 is transmitted to the periphery of the connecting protrusion 11. Here, the transmission of the load is suppressed at the boundary between the protrusion and the recess, and the load is transmitted along the protrusion. More specifically, the load received by the connecting protrusion 11 is transmitted in the order of the peripheral protrusion 12, the connecting protrusion 14, and the arc-shaped protrusion 13. A central recess 15 exists inside the arc-shaped protrusion 13, preventing the load from being transmitted to the central portion of the bottom plate 1. In other words, the load is not concentrated in the central portion of the bottom plate 1, but is distributed throughout the entire bottom plate 1. This makes it possible to reduce the amount of deformation when a load is received.

[0042] The bottom plate 1 also has a plurality of convex portions and concave portions, which improves the section modulus of the bottom plate 1, improves the rigidity of the bottom plate 1, and makes it possible to reduce the amount of deformation when subjected to a load.

[0043] Furthermore, all of the curved portions of the boundary lines between the multiple convex and concave portions are chamfered or rounded, and there are no extremely sharp angles, which makes it possible to avoid the occurrence of areas where stress is concentrated.

[0044] Furthermore, the center C of the arc-shaped convex portion 13 is located on the line of the central axis S of the hot water storage tank 2. This allows the load to be distributed evenly onto the bottom plate 1.

[0045] The hot water storage tank 2 is an example of a load, the bottom plate 1 is an example of a bottom plate, the connecting protrusion 11 is an example of a connecting protrusion, the peripheral protrusion 12 is an example of a peripheral protrusion, the arc-shaped protrusion 13 is an example of an annular protrusion and an arc-shaped protrusion, the connecting protrusion 14 is an example of a connecting protrusion, the central recess 15 is an example of a central recess, the peripheral recess 16 is an example of a recess, the center C is an example of a center, the central axis S is an example of a central axis, and the buffer materials 33A and 33B are examples of buffer materials. The combination of the hot water storage tank 2 and the bottom plate 1 supporting it corresponds to a hot water storage device.

[0046] The present disclosure is not limited to the above-described embodiment and may be modified. For example, in the above-described embodiment, the connecting protrusions 11 are not continuous with the arc-shaped protrusions 13. However, as shown in FIG. 3 , the connecting protrusions 11 may be continuous with the arc-shaped protrusions 13. In this configuration, the connecting protrusions 11 and the arc-shaped protrusions 13 are connected and the connecting protrusions 11 are sandwiched between the peripheral recesses 16. Therefore, a load applied to the connecting protrusions 11 is transmitted to the arc-shaped protrusions 13. However, the load is transmitted from the arc-shaped protrusions 13 to the peripheral edge protrusions 12 via the connecting protrusions 14, and is not transmitted to the center of the bottom plate 1. With this configuration, when manufacturing the bottom plate 1 by press working, for example, the amount of unevenness on the entire bottom plate 1 can be reduced, thereby improving the formability of the bottom plate 1.

[0047] Furthermore, in the configurations of Figures 1, 2, and 3, the bottom plate 1 has a plurality of arc-shaped convex portions 13 separated from each other and connecting convex portions 14 that connect the arc-shaped convex portions 13 to the peripheral convex portion 12, but this is not limited to this form.

[0048] 4A, for example, one continuous annular convex portion 13A is formed, and the connecting convex portion 11 and the annular convex portion 13A are continuous. In this configuration, a load applied to a connecting convex portion 11 is transmitted to the entire annular convex portion 13A, but is not transmitted to the center of the bottom plate 1.

[0049] 4(B), the connecting protrusion 11 and the annular protrusion 13A are not continuous. In this configuration, the load applied to a connecting protrusion 11 is not directly transmitted to the annular protrusion 13A, and even if a portion of the load is transmitted, it is not transmitted to the center of the bottom plate 1.

[0050] As described above, these configurations can improve formability when manufacturing the bottom plate 1. The annular convex portion 13A is an example of an annular convex portion.

[0051] Furthermore, in the above embodiment, the bottom plate 1 includes the arc-shaped convex portion 13 and the central recess 15 inside the annular convex portion 13A, but is not limited to this. For example, in the configurations shown in Figures 5(A) to 5(E), the bottom plate 1 does not include the annular convex portion 13A and the central recess 15, but includes a circular convex portion 19 that is circular in plan view. The circular convex portion 19 corresponds to a configuration including the annular convex portion 13A and a central convex portion connected thereto. The diameter of the convex surface of the circular convex portion 19 is arbitrary, but is, for example, approximately 30 to 60% of the length of one side of the bottom plate 1. According to this configuration, as described above, the formability when manufacturing the bottom plate 1 can be improved. The circular convex portion 19 is an example of an annular convex portion and an arc-shaped convex portion.

[0052] In this embodiment, as shown in Fig. 5(A), the bottom plate 1 may not have the connecting protrusions 14, and the linking protrusions 11 may be continuous with the circular protrusions 19. Alternatively, as shown in Fig. 5(B), the bottom plate 1 may not have the connecting protrusions 14, and the linking protrusions 11 may not be continuous with the circular protrusions 19. Alternatively, as shown in Fig. 5(C), the bottom plate 1 may have the connecting protrusions 14, and the linking protrusions 11 may be continuous with the circular protrusions 19. Alternatively, as shown in Fig. 5(D), the bottom plate 1 may have the connecting protrusions 14, and the linking protrusions 11 may not be continuous with the circular protrusions 19.

[0053] Furthermore, in the above embodiment, the bottom plate 1 has three connecting protrusions 11, but this is not limited to this. For example, the bottom plate 1 may have four or more connecting protrusions 11. In this case, the base 31 of the hot water storage tank 2 has connecting holes HC equal to the number of connecting protrusions 11 provided on the bottom plate 1. The intervals at which the connecting holes HC are drilled are equal to the intervals at which the connecting holes HA are drilled on the connecting protrusions 11 in the bottom plate 1, and L-shaped metal fittings 32 are connected to the connecting holes HC of the base 31.

[0054] When the bottom plate 1 has four or more connecting protrusions 11, the bottom plate 1 may have four or more connecting protrusions 14. In this case, the connecting protrusions 14 are provided in the area between adjacent connecting protrusions 11 on the bottom plate 1, and the number of connecting protrusions 14 is the same as the number of connecting protrusions 11. For example, when the bottom plate 1 has five connecting protrusions 11, the bottom plate 1 has five connecting protrusions 14.

[0055] In the above embodiment, the connecting protrusions 11 are arranged at equal distances from the center C and at equal intervals in the circumferential direction, but this is not limiting. The distances from the center C of each connecting protrusion 11 may be different. The intervals between each connecting protrusion 11 may also be different.

[0056] 6, the end of the connecting protrusion 11 may be rounded into a semicircular shape. In addition to the form where the end is rounded into a semicircular shape, only the corners of the connecting protrusion 11 may be chamfered. This makes it possible to prevent stress from concentrating on a specific part of the connecting protrusion 11, thereby suppressing deformation of the bottom plate 1. In the form where the end of the connecting protrusion 11 is rounded into a semicircular shape, it is desirable from the viewpoint of formability to leave a gap of 30 mm or more between the connecting protrusion 11 and the arc-shaped protrusion 13.

[0057] In the above embodiment, the connecting protrusions 11, peripheral protrusions 12, arcuate protrusions 13, annular protrusions 13A, and connecting protrusions 14 are each formed in a convex shape on the upper surface of the bottom plate 1, but this is not limiting. For example, the connecting protrusions 11, peripheral protrusions 12, arcuate protrusions 13, annular protrusions 13A, and connecting protrusions 14 may each be formed in a convex shape on the lower surface of the bottom plate 1.

[0058] In the above embodiment, the hot water storage tank 2 is connected to the bottom plate 1, and then the bottom plate 1 connected to the hot water storage tank 2 is connected to the housing 5. However, this order is not limited to this. For example, the bottom plate 1 may be connected to the housing 5 first, and then the bottom plate 1 connected to the housing 5 may be connected to the hot water storage tank 2.

[0059] In the above embodiment, the hot water tank 2 is placed on the bottom plate 1, but the load is not limited to the hot water tank 2. For example, instead of the hot water tank 2, a refrigerator, a washing machine, or other loads can be placed on the bottom plate 1.

[0060] In the above embodiment, the connecting holes HC, the arcuate convex portions 13, the connecting convex portions 14, the extending concave portions 15A, and the peripheral concave portions 16 of the base 31 are provided at three locations at equal intervals of approximately 120°, but this is not limitative. The angle defining the intervals, the number, etc. can be changed as appropriate.

[0061] In this disclosure, expressions such as "equally spaced," "equally distant," and "equally angular" do not mean strictly equal intervals, equal distances, or equal angles. Deviations due to errors, design adjustments and changes, etc. are permitted within the scope of achieving the function of the bottom plate or hot water storage device. Furthermore, terms such as "arc-shaped," "annular," "circular," and "ring-shaped" do not mean strict shapes. For example, "arc" broadly refers to the arc of a perfect circle, the arc of an ellipse, an arc of a figure approximating a circle, an arc of a figure formed by a curve, etc. Furthermore, "annular," "circle," and "ring" broadly refer to the arc of a perfect circle, an ellipse, a figure approximating a circle, a figure formed by a curve, etc.

[0062] This application is based on Japanese Patent Application No. 2023-111107, filed on July 6, 2023. The entire specification, claims, and drawings of Japanese Patent Application No. 2023-111107 are incorporated herein by reference.

[0063] The following are appendices to the present disclosure. (Appendix 1) A bottom plate laid beneath a load, comprising: a plurality of connecting protrusions connectable to the load and convex in a direction perpendicular to the plate surface of the bottom plate; and an annular protrusion arranged in an area surrounded by the connecting protrusions. (Appendix 2) The bottom plate described in Appendix 1, wherein the annular protrusion comprises a plurality of arc-shaped protrusions arranged at a distance from each other or one annular protrusion, and the bottom plate has a central recess inside the annular protrusion and in an area including the center of the bottom plate, the central recess being recessed relative to the annular protrusion. (Appendix 3) The bottom plate described in Appendix 1 or 2, wherein the annular protrusion comprises a circular protrusion formed in an area including the center of the bottom plate. (Appendix 4) The bottom plate described in any one of Appendices 1 to 3, wherein an area between the connecting protrusions and the annular protrusion is recessed relative to the connecting protrusions and the annular protrusion. (Appendix 5) The bottom plate according to any one of Appendices 1 to 4, wherein the bottom plate comprises a convex peripheral convex portion formed on the peripheral edge of the bottom plate, and a convex connecting convex portion connecting the annular convex portion and the peripheral convex portion. (Appendix 6) The bottom plate according to any one of Appendices 1 to 5, wherein the center of the annular convex portion is located on the central axis of the load. (Appendix 7) The bottom plate according to any one of Appendices 1 to 6, wherein the bottom plate comprises a cushioning material on the surface of the connecting convex portion on which the load is placed. (Appendix 8) The bottom plate according to any one of Appendices 1 to 7, wherein the connecting convex portions are arranged at equal distances from the center of the bottom plate and at equal intervals in the circumferential direction. (Appendix 9) The bottom plate according to any one of Appendices 1 to 8, wherein the edges of the connecting convex portions are rounded. (Supplementary Note 10) A hot water storage device comprising: a bottom plate according to any one of Supplementary Notes 1 to 9; and a hot water storage tank connected to the connecting protrusion of the bottom plate and supported by the bottom plate.

[0064] 1 bottom plate, 11 connecting protrusion, 12 peripheral protrusion, 13 arc-shaped protrusion, 13A annular protrusion, 14 connecting protrusion, 15 central recess, 15A extending recess, 16 peripheral recess, 17 edge, 18 fixing portion, 19 circular protrusion, 2 hot water storage tank, 31 unit, 32 L-shaped metal fitting, 33 buffer material, 34 bolt, 35 nut, 36 insulation material, 4 heating device, 5 housing, 6 heat pump type hot water heater, W1 width, W2 width, W3 width, W4 width, W5 diameter, C center, HA connecting hole, HB connecting hole, HC connecting hole, HD connecting hole, HE connecting hole, HF connecting hole, L height, S central axis.

Claims

1. A bottom plate laid under the load, a plurality of connecting projections that can be connected to the load and that are projecting in a direction perpendicular to the surface of the bottom plate; an annular protrusion disposed in an area surrounded by the connecting protrusion; a recess provided between the connecting protrusion and the annular protrusion and recessed relative to the connecting protrusion and the annular protrusion; Equipped with The bottom plate has the connecting protrusions arranged in a radial direction from the center of the ring of the annular protrusion, and the recesses are formed between the connecting protrusions and the annular protrusions in the radial direction.

2. the annular protrusion includes a plurality of arcuate protrusions arranged at a distance from one another, or a single annular protrusion; the bottom plate is provided with a central recess at the center of the bottom plate, the central recess being inside the annular protrusion and recessed relatively to the annular protrusion; The base plate according to claim 1 .

3. A plurality of extending recesses extending radially from the central recess. The base plate according to claim 2.

4. The annular protrusion includes a circular protrusion formed in an area including the center of the bottom plate. The base plate according to claim 1 .

5. The bottom plate has an upright wall-like edge portion that incorporates a peripheral edge portion of the bottom plate; a convex peripheral edge portion formed adjacent to the edge portion and along the entire periphery of the edge portion; a connecting protrusion having a convex shape extending in a radial direction from the center of the ring of the annular protrusion, which connects the annular protrusion and the peripheral edge protrusion, The base plate according to claim 1 .

6. The connecting protrusion protrudes from the peripheral protrusion toward the recess. The base plate according to claim 5.

7. The center of the annular protrusion is located on the central axis of the load. The base plate according to claim 1 .

8. The bottom plate includes a cushioning material on a surface of the connecting protrusion on which the load is placed. The base plate according to claim 1 .

9. The connecting protrusions are arranged at positions equidistant from the center of the bottom plate and equidistantly spaced in the circumferential direction. The base plate according to claim 1 .

10. The edge of the connecting protrusion is rounded. The base plate according to claim 1 .

11. A bottom plate according to any one of claims 1 to 10; a hot water storage tank connected to the connecting protrusion of the bottom plate and supported by the bottom plate, Hot water storage device.