JP7344437B2 - Heat exchanger and electric water heater - Google Patents

Description

The present invention relates to an instantaneous heat exchanger and an electric water heater equipped with the heat exchanger.

Conventionally, instantaneous heat exchangers have been widely used in electric water heaters and the like. For example, Patent Document 1 describes a faucet device using an instantaneous heat exchanger.

As a structural example of an instantaneous heat exchanger, one disclosed in Patent Document 2 is known. The heat exchanger 101 disclosed in Patent Document 2 is widely used as a heat exchanger for sanitary cleaning devices (for example, Washlet (registered trademark)), and as shown in FIGS. 3 and 4, the heat exchanger 101 has a cylindrical outer periphery. A heating element 102 having a surface, a cylindrical case 103 (the outer shape is a rectangular parallelepiped but the inner peripheral surface is cylindrical) that covers the outer peripheral surface of the heating element 102, and a case 103 that extends from the inner peripheral surface of the case 103 toward the outer peripheral surface of the heating element 102. A flow path regulating wall 112 that protrudes and extends spirally along the axial direction of the heat generating element 102; In this case, a coil spring 111 that is in continuous and tight contact with the case 103 in a spiral manner is also provided.

In the space between the inner circumferential surface of the case 103 and the outer circumferential surface of the heating element 102, the coil spring 111 and the flow path regulating wall 112 cooperate to form a flow path extending in a spiral shape. There is. While the water flows through the flow path, heat is exchanged with the outer circumferential surface of the heating element 102, and the water becomes hot water (hot water). For example, water is introduced from the water inlet 104 at one end of the heating element 102, exits from the other end of the heating element 102, collides with the end wall of the case 103, and then flows through the spirally formed flow path. The water is discharged from the spout 105 at the top of the case 103.

JP2017-36877A JP2012-88031A

When used as a sanitary cleaning device, the amount of hot water to be supplied is sufficient to be 0.5 L/min. However, when using a general electric water heater, the amount of hot water to be supplied is desirably about 2 L/min.

In order to achieve such an increase in the amount of hot water, the inventor of the present invention has repeatedly considered expanding each part of the configuration disclosed in Patent Document 2 proportionally (while maintaining the similarity of each part).

Regarding the heating element, the case, and the flow path regulating wall, no particular problem occurred in proportionally increasing their dimensions. However, when the dimensions of a coil spring are expanded proportionally, the coil spring becomes too thick and the spring constant becomes excessive, making it difficult to assemble the coil spring to the heating element, or the excessive elastic force causes the heating element to It is expected that problems such as damage may occur.

On the other hand, if only the dimensions of other parts are expanded without increasing the diameter of the coil spring, the position of the coil spring is likely to shift, and normally the coil spring and flow path regulating wall would not work together to form a spiral. In areas where a flow path extending in a straight shape should be formed, there are areas where the flow path regulation by coil springs is insufficient between adjacent pitches, causing the flow path to become short-circuited and reducing heat transfer efficiency. confirmed.

The present invention has been made based on the above findings. An object of the present invention is to provide an instantaneous heat exchanger, which includes a heating element having a cylindrical outer circumferential surface, a case that covers the outer circumferential surface of the heating element, and a heat exchanger that connects the heating element from the inner circumferential surface of the case. a flow path regulating wall that protrudes toward the outer peripheral surface and extends spirally along the axial direction of the heating element; A heat exchanger equipped with a flow-path regulating elastic body (for example, a coil spring) that can also come into contact with a wall, suppressing the occurrence of positional deviation of the flow-path regulating elastic body and reducing heat transfer efficiency. It is an object of the present invention to provide a heat exchanger that can suppress

The present invention provides an instantaneous heat exchanger, which includes a heating element having a cylindrical outer peripheral surface, a case that covers the outer peripheral surface of the heating element, and a case that extends from the inner peripheral surface of the case to the outer periphery of the heating element. a flow path regulating wall that protrudes toward the surface and extends spirally along the axial direction of the heating element; a flow-path regulating elastic body that can also come into contact with a wall, and the flow-path regulating wall has a unilateral protrusion on one side when viewed in the axial direction of the heat generating element on a surface facing the heat generating element. and a concave portion between the one side protrusion and the other side protrusion, and the one side protrusion is located at a position overlapping with the flow path regulating elastic body. The heat exchanger is characterized in that the other side protrusion also protrudes to a position overlapping with the flow path regulating elastic body.

According to the present invention, the flow path regulating wall includes, on the surface facing the heating element, the one-side protrusion on one side, the other-side protrusion on the other side, the one-side protrusion, and the other side when viewed in the axial direction of the heating element. The protrusion on one side protrudes to a position where it overlaps with the flow-path regulating elastic body, and the protrusion on the other side also extends to a position where it overlaps with the flow-path regulating elastic body. Because of the protrusion, both the one side protrusion and the other side protrusion can effectively suppress the occurrence of positional deviation of the flow path regulating elastic body in the axial direction of the heating element.

Preferably, the flow path regulating elastic body is made of a coil spring. According to this, a flow path regulating elastic body having desired characteristics can be easily selected from a wide range of options.

It is preferable that a gap is provided between the one side protrusion and the flow path regulating elastic body and/or between the other side protrusion and the flow path regulating elastic body. According to this, the gap can easily absorb dimensional errors and thermal deformation of the flow path regulating elastic body (for example, a coil spring).

Furthermore, by making the recess sufficiently deep, it is possible to easily absorb dimensional errors in the heating element, deformation (especially expansion) due to heat, and deformation of the channel elastic body during assembly.

Moreover, it is preferable that the pitch of the flow path regulating wall is larger than the width of the flow channel regulating wall itself. According to this, higher heat transfer efficiency can be achieved.

Further, the present invention is an electric water heater equipped with a heat exchanger having any of the above characteristics. According to the electric water heater of the present invention, a sufficient amount of hot water can be provided with sufficient heat transfer efficiency.

According to the present invention, the flow-path regulating wall protrudes to a position that overlaps with the flow-path regulating elastic body in the vicinity of one side of the flow-path regulating elastic body when viewed in the axial direction of the heating element, and Near the other side of the flow-path regulating elastic body, it protrudes to a position that overlaps with the flow-path regulating elastic body, so it is possible to prevent the occurrence of positional deviation of the flow-path regulating elastic body in the axial direction of the heating element. It can be effectively suppressed by both the protrusion near one side and the protrusion near the other side.

1 is a schematic cross-sectional view of a heat exchanger according to an embodiment of the present invention. 2 is an enlarged view of section II in FIG. 1. FIG. FIG. 2 is a cross-sectional view of the heat exchanger disclosed in Patent Document 2 (this is a diagram corresponding to FIG. 1 of Patent Document 2). It is a partially cutaway cross-sectional perspective view of the heat exchanger disclosed in Patent Document 2 (this is a view corresponding to FIG. 2 of Patent Document 2).

Next, a heat exchanger according to an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view of a heat exchanger 1 according to an embodiment of the present invention, and FIG. 2 is an enlarged view of section II in FIG. 1.

As shown in FIGS. 1 and 2, the heat exchanger 1 is a so-called instantaneous heat exchanger, and includes a heating element 2 having a cylindrical (an example of a cylindrical) outer peripheral surface, and an outer periphery of the heating element 2. A case 3 has a cylindrical shape (a cylinder with a bottom) that covers the surface, and a case 3 protrudes from the inner peripheral surface of the case 3 toward the outer peripheral surface of the heating element 2 and extends in a spiral along the axial direction of the heating element 2. It includes a flow path regulating wall 12 and a coil spring 11 that is in close contact with the outer circumferential surface of the heating element 2 in a spiral manner and can also come into contact with the flow channel regulating wall 12.

In particular, as shown in FIG. 2, the flow path regulating wall 12 extends to a position where it overlaps with the coil spring 11 (the upper end of the coil spring 11) near the left side (one side) of the coil spring 11 when viewed in the axial direction of the heating element 2. It also protrudes to a position that overlaps with the coil spring 11 (below the upper end of the coil spring 11) near the right side (other side) of the coil spring 11.

That is, the flow path regulating wall 12 includes a one-side protrusion 12 a that protrudes to a position overlapping the coil spring 11 in the vicinity of the left side (one side) of the coil spring 11 when viewed in the axial direction of the heat generating element 2 , and It has another side protrusion 12c that protrudes to a position overlapping with the coil spring 11 near the right side (other side) of the coil spring 11 when viewed in the axial direction.

Although the flow path regulating wall 12 is formed integrally with the case 3 in this embodiment, the flow path regulating wall 12 may be formed separately and then connected to each other in a watertight manner.

Furthermore, in the present embodiment, as shown in FIG. A gap is provided between the other side protrusion 12c and the coil spring 11 when viewed in the axial direction.

Further, in this embodiment, as shown in FIG. 2, a recess 12b that is recessed toward the inner peripheral surface of the case 3 with respect to the coil spring 11 is provided between the one side protrusion 12a and the other side protrusion 12c. ing.

In the space between the inner peripheral surface of the case 3 and the outer peripheral surface of the heating element 2, the coil spring 11 and the flow path regulating wall 12 cooperate to form a flow path extending in a spiral shape. There is.

Here, as described above, gaps remain between the one side protrusion 12a and the coil spring 11 and between the other side protrusion 12c and the coil spring 11. However, the size of the gap is kept to a size that does not cause a substantial "short circuit" in the spiral flow path, so that no significant reduction in heat transfer efficiency occurs.

The heating element 2 is, for example, a ceramic pipe heater, and is configured to generate heat from its inner and outer peripheral surfaces to heat water passing through the inner and outer peripheral sides of the heating element 2. In the heating element 2, a band-shaped heater pattern made of tungsten or the like is formed along the axial direction by printing or the like inside an exterior portion made of ceramic, for example. The opening at the end of the pipe-shaped heating element 2 opposite to the side inserted into the case 3 serves as the water inlet 4 of the heat exchanger 1.

The case 3 has a cylindrical shape with a bottom and is made of resin or metal.

With the above configuration, while water flows through the spirally formed channel, heat is exchanged mainly with the outer peripheral surface of the heating element 2, so that the water becomes hot water (hot water). It has become. For example, as shown in FIG. 1, water is introduced from the water inlet 4 at one end of the heating element 2, exits from the other end of the heating element 2, collides with the end wall of the case 103, and then spirals. It passes through the formed flow path and is discharged from the spout 5 at the top of the case 3.

To give an example of the dimensional ratio of each part, as shown in FIG. The distance from the right end (other end) of the protrusion 12c to the right end (other end) of the protrusion 12c is W1, and the distance from the right end (other end) of the one protrusion 12a to the left end (the other end) of the other protrusion 12c when viewed in the axial direction of the heating element 2. one side end) is W2, the height from the outer peripheral surface of the heating element 2 to the inner peripheral surface of the case 3 is H1, and the height from the outer peripheral surface of the heating element 2 to the deepest part of the recess 12b is H2. , the pitch of the flow-path regulating wall 12 is P, and the cross-sectional area of the flow channel (spiral, pitch P) formed by the heating element 2, the inner peripheral surface of the case 3, and the flow-path regulating wall 12 is S. Then, S=(P-W2)×H1. The smaller the flow path cross-sectional area S, the higher the flow velocity and the higher the heat transfer coefficient, but the pressure loss also increases. For this reason, it is preferable to adopt optimal design dimensions depending on the flow rate.

According to the knowledge of the inventor of the present invention, in the case of a flow rate of 2 L/min, it is preferable that the flow path cross-sectional area S=17 mm ² , for example. Further, the cross-sectional shape of the flow path cross-sectional area S is preferably a square or a horizontally long rectangle, for example, H1:(P-W2)=2:7. An example of the clearance between the coil diameter D and the flow path regulating wall 12 is approximately W2=D×1.2 and H2=D×2 approximately. 2.0×D≦W2≦3.0×D, 1.1×D≦W1≦1.3×D, 1.5×D≦H2≦2.5×D, 4.0×D≦P≦ 10.0×D may be exemplified as a suitable range.

Note that the area occupied by the distance W1 corresponds to an area in the space between the inner circumferential surface of the case 3 and the outer circumferential surface of the heat generating element 2 where water cannot substantially flow therethrough. Therefore, the distance W1 is also called the width of the flow path regulating wall 12.

Next, a method for assembling the heat exchanger 1 of this embodiment will be explained.

The coil spring 11 is selected so that its inner diameter is smaller than the outer diameter of the outer peripheral surface of the heating element 2. Then, the coil spring 11 is inserted into the case 3 by screwing it into the spiral groove formed by the recess 12b of the flow path regulating wall 12. After the insertion is completed, the inner diameter is expanded by further compressing the coil spring 11 in its stretching direction (twisting in the helical and forward directions) (at this time, the height H2 of the recess 12b functions). In this state, the heating element 2 is inserted into the case 3 and the coil spring 11. Thereafter, by releasing the compression (twisting) of the coil spring 11, the coil spring 11 is continuously and tightly adhered to the outer peripheral surface of the heating element 2 in a spiral manner due to the elastic force of the coil spring 11 itself.

Here, according to the present embodiment, the one side protrusion 12a protrudes to a position overlapping with the coil spring 11 in the vicinity of the left side (one side) of the coil spring 11 when viewed in the axial direction of the heat generating element 2; The other side protrusion 12c protrudes to a position overlapping the coil spring 11 near the right side (other side) of the coil spring 11 when viewed in the axial direction. Therefore, during the above-mentioned assembly work, and furthermore, when water flows after the assembly work, the occurrence of positional deviation of the coil spring 11 in the axial direction of the heating element 2 can be prevented from occurring between the one side protrusion 12a and the other side. This can be effectively suppressed by the presence of both the protruding portion 12c and the protruding portion 12c.

As a result, it is possible to effectively suppress the occurrence of a problem in which a portion where the flow path is insufficiently regulated by the coil spring 11 appears and the flow path becomes "short-circuited" and the heat transfer efficiency decreases.

Moreover, according to the heat exchanger 1 of this embodiment, gaps remain between the one side protrusion 12a and the coil spring 11 and between the other side protrusion 12c and the coil spring 11. These gaps can play the role of easily absorbing dimensional errors in the coil spring 11 and deformation due to heat.

Moreover, according to the heat exchanger 1 of this embodiment, the recessed part 12b is provided between the one side protrusion part 12a and the other side protrusion part 12c. This recess 12b can play the role of easily absorbing dimensional errors in the heating element 2 and deformation of the spring during assembly.

Moreover, according to the heat exchanger 1 of this embodiment, the pitch P of the flow path regulating wall 12 is larger than the width W1 of the flow channel regulating wall 12 itself. This makes it possible to achieve higher heat transfer efficiency.

The heat exchanger 1 of this embodiment described above can be used as a main component of an electric water heater. Such an electric water heater can provide a sufficient amount of hot water with sufficient heat transfer efficiency.

In addition, in the heat exchanger 1 of this embodiment described above, as shown in FIG. are equal. However, their degree of protrusion does not necessarily have to be the same.

Further, in the heat exchanger 1 of the present embodiment described above, the coil spring 11 whose strand cross section is circular is used, but other flow path regulating elastic bodies whose strand cross section is not circular are used. Good too. However, since a wide variety of coil springs are available at low cost, if a coil spring is used as the flow-path regulating elastic body, it is easy to select a flow-path regulating elastic body with the desired characteristics from a wide range of options. be able to.

1 Heat exchanger 2 Heating element 3 Case 4 Water inlet 5 Water outlet 11 Coil spring 12 Flow path regulating wall 12a One side protrusion 12b Recess 12c Other side protrusion 101 Heat exchanger 102 Heating element 103 Case 104 Water inlet 105 Water outlet 111 Coil spring 112 Flow path regulating wall

Claims (5)

It is an instantaneous heat exchanger,
a heating element having a cylindrical outer peripheral surface;
a case that covers the outer peripheral surface of the heating element;
A flow path regulating wall that restricts a flow path by protruding from an inner circumferential surface of the case toward the outer circumferential surface of the heat generating element, and extending in a spiral shape along the axial direction of the heat generating element. a spiral flow path regulating wall that spirally regulates the flow path;
a flow path regulating elastic body that continuously contacts the outer circumferential surface of the heating element in a spiral manner and is also capable of contacting the spiral flow channel regulating wall;
Equipped with
The helical flow path regulating wall includes a one-side protrusion on one side as viewed in the axial direction of the heating element, and a protrusion on one side as viewed in the axial direction of the heating element, in a portion that partitions adjacent flow paths when viewed in the axial direction of the heating element. and a recess between the one side protrusion and the other side protrusion when viewed in the axial direction of the heating element ,
The flow path regulating elastic body is located in a region corresponding to the recess when viewed in the axial direction of the heating element,
The one side protrusion protrudes to a height that overlaps with the flow path regulating elastic body,
The heat exchanger characterized in that the other side protrusion also protrudes to a height position overlapping with the flow path regulating elastic body. The heat exchanger according to claim 1, wherein the flow path regulating elastic body is made of a coil spring. A claim characterized in that a gap is provided between the one side protrusion and the flow path regulating elastic body and/or between the other side protrusion and the flow path regulating elastic body. The heat exchanger according to item 1 or 2. The heat exchanger according to any one of claims 1 to 3, wherein the pitch of the helical flow path regulating wall is larger than the width of the helical flow path regulating wall itself. An electric water heater comprising the heat exchanger according to any one of claims 1 to 4.

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