Liquid heating device

Abstract

To provide a liquid heating device that allows for easy and reliable electrical connection of electrode pads of a ceramic heater with terminals.SOLUTION: A liquid heating device 200 comprises: a flow passage member 100 having an internal space 100i in which liquid W flows, an introduction port 103 and a discharge port 105 which are in communication with the internal space; and a ceramic heater 171 having a power generation part 17a extending in an axial line direction L and generating power in response to energization, and two or more electrode pads 17p arranged on an outer surface and electrically connected to the power generation part, the ceramic heater 171 being attached to the flow passage member. Liquid is heated by the ceramic heater during a course of the liquid being introduced from the introduction port and flowing to the discharge port through the internal space. The liquid heating device further comprises two or more terminals 122 which are pushed against the electrode pads at respective one-side end parts 122s to be electrically connected to the electrode pads, a spring 124 for pressing the terminals toward the electrode pads in a radial direction, and a holding part 126 for locking a radially outer end part of the spring.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a liquid heating device that heats a liquid such as water using a ceramic heater.

Background Art

[0002] Hot water is required for a warm water washing toilet seat, a fuel cell system, a water heater, a 24-hour bath, heating of a vehicle washer fluid, and an air conditioner of an electric vehicle, etc. Therefore, a hot water heating device that heats water with a built-in ceramic heater and uses it for vehicle air conditioning as hot water is known (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in order to electrically heat the ceramic heater used in the liquid heating device, generally, an external terminal or a lead wire is brazed to an electrode pad (terminal portion) on the ceramic heater side with silver brazing or the like. On the other hand, in order to attach the ceramic heater to the device, a flange portion of the ceramic heater is brazed with glass. However, after brazing the flange portion of the ceramic heater with glass, when brazing an external terminal to the electrode pad, the previously brazed glass may melt and the flange portion may fall off. Conversely, when brazing an external terminal to the electrode pad first, the brazed portion of the external terminal may melt when brazing the flange portion with glass. For this reason, there is a problem that heat countermeasures for the previously brazed portion are required, or the brazing work at two locations is complicated, resulting in low productivity.

[0005] Therefore, the present invention aims to provide a liquid heating device that enables simple and reliable electrical connection between the electrode pads and terminals of a ceramic heater. [Means for solving the problem]

[0006] To solve the above problems, the present invention provides a liquid heating device comprising: a flow path member having an internal space through which liquid flows, and an inlet and an outlet communicating with the internal space; a ceramic heater attached to the internal space of the flow path member, having a heating element extending in the axial direction and generating heat when energized, and two or more electrode pads arranged on the outer surface and electrically connected to the heating element; a liquid heating device in which the liquid is heated by at least the outer surface of the ceramic heater in the process of the liquid being introduced from the inlet and flowing through the internal space to the outlet, wherein the electrode pads are arranged outside the internal space and further comprise two or more terminals, one end of which is pressed against each of the electrode pads and electrically connected; a spring that presses the terminals radially toward the electrode pads; and a holding part that locks the radially outer end of the spring. The flow path member and the holding part are separate, and the holding part is inserted from the radially outward direction into a first opening facing radially outward of the flow path member, and further comprises a stopper that is locked to the flow path member, the stopper engaging with the holding part. It is characterized by the following.

[0007] With this liquid heating device, the electrode pads and terminals are connected simply by pressure contact, eliminating the need for complicated procedures such as brazing, and allowing for easy and reliable electrical connection between the electrode pads and terminals. Furthermore, if, for example, a spring terminal is used with an electrode pad, the spring terminal drags the electrode pad, scraping the electrode material, and this scraping material becomes electrically conductive, causing a leakage problem. However, the present invention has the advantage of not causing such dragging.

[0008] Also, In this liquid heating device, the flow path member and the holding part are separate, and by using a stopper separate from the holding part, the holding part can first be pressed radially inward to compress the spring radially, and then the holding part can be locked with the stopper, making it easier to press each terminal against the electrode pad.

[0009] In the liquid heating apparatus of the present invention, when viewed from the axial direction, the ends of the terminals may be arranged at equal intervals on the circumference of the same virtual circle. With this liquid heating device, the resultant force P of the radially inward pressing force of each terminal is canceled out at the center of the virtual circle, and a resultant force is generated in a predetermined direction at the center of the virtual circle, which suppresses bending stress and the like acting on the ceramic heater 171.

[0010] In the liquid heating apparatus of the present invention, the end face of the end of the terminal may be flat, and the outer surface of the electrode pad may be curved so as to be convex radially outward. With this liquid heating device, the protrusions of the electrode pads make sure to contact the flat surface at the end of the terminal, resulting in a more reliable electrical connection between the electrode pads and the terminals. [Effects of the Invention]

[0011] According to this invention, the electrical connection between the electrode pads and terminals of a ceramic heater can be made simple and reliable. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view showing the external appearance of a liquid heating device according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view along line AA in Figure 1. [Figure 3] This is a perspective view showing the appearance of a ceramic heater. [Figure 4] This is an exploded perspective view showing the configuration of a ceramic heater. [Figure 5] This is an exploded perspective view of the area near the terminals of a liquid heating device. [Figure 6] This is a cross-sectional view along line BB in Figure 5. [Figure 7] This is a plan view showing the relative positions of each terminal when viewed from the axial direction. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the present invention will be described. FIG. 1 is a perspective view of a liquid heating device 200 according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1, FIG. 3 is a perspective view of a ceramic heater 171, and FIG. 4 is an exploded perspective view of the ceramic heater 171. In FIGS. 1, 2, and FIGS. 5 and 6 described later, the inlet 103 side is referred to as the "rear end side".

[0014] In this embodiment, the liquid heating device 200 is installed in an electric vehicle (EV) and is configured to heat water by one built-in ceramic heater 171 to supply warm water. The supplied warm water can be used, for example, for winter heating or battery heat preservation.

[0015] The liquid heating device 200 generally has a substantially box shape and includes a substantially cylindrical flow path member (container) 100 and a large box-shaped circuit housing portion 110 integrally connected to the outer surface of the flow path member 100. Further, one ceramic heater 171 is provided inside the flow path member 100. The flow path member 100 and the circuit housing portion 110 are made of resin. As shown in FIG. 2, the flow path member 100 has a cylindrical portion 101 having an internal space 100i for accommodating the liquid W (water). Further, the flow path member 100 has an inlet 103 for the liquid W along the axial direction of the axis L while communicating with the internal space 100i, and has an outlet 105 for the liquid W along a direction intersecting the axial direction of the axis L while communicating with the internal space 100i. In this example, a ceramic heater 171 extending in the axial direction of the axis L is arranged along the axial direction of the flow path member 100. Therefore, the axial direction of the flow path member 100 is also referred to as the "axial direction of the axis L". Note that the flow path member 100 and the circuit housing portion 110 are not limited to being made of resin, and may be made of metal, for example.

[0016] At the base of the inlet 103 opposite the tip, two terminal housings 121a and 121b are integrally formed, facing each other radially outward. A flange portion 103f is also integrally formed at the base of the inlet 103, and the flange portion 103f is bolted to the cylindrical portion 101, closing the rear end opening of the cylindrical portion 101. On the other hand, the discharge port 105 is integrated with the cylindrical portion 101 and is positioned closer to the rear end of the cylindrical portion 101. Furthermore, the lower cover 107 closes the tip opening of the cylindrical portion 101 via the sealing member 115.

[0017] The ceramic heater 171 is rod-shaped and extends in the axial direction L, and is attached to the internal space 100i of the flow path member 100. In detail, the ceramic heater 171 is positioned with its heating element 17a facing the tip, and is located within the internal space 100i with a gap between it and the flow channel member 100. Meanwhile, a donut-shaped flange portion 19 is connected to the rear end of the ceramic heater 171 by brazing BR. The flange portion 19 and the flow path member 100 are airtightly sealed by pressing the tip-facing surface of the flange portion 19 against the periphery of the rear end opening of the cylindrical portion 101 via the sealing member 113. Furthermore, the flange portion 19 is pressed towards the front end from the rear end by the flange portion 103f of the inlet 103. Furthermore, the heating element 17a can be placed anywhere that comes into contact with the target liquid W, not limited to the tip of the ceramic heater 171, as long as it generates heat when an electric current is applied.

[0018] Furthermore, the two electrode pads 17p (described later) of the ceramic heater 171 are located on the rear end side of the flange portion 19 and face the inside of the terminal housing portions 121a and 121b of the inlet 103. The rear end of the ceramic heater 171 is aligned with the axis of the inlet 103 and connected to the inlet 103 via the sealing member 111. Two electrode pads 17p are connected to two terminals 122, which will be described later, and lead wires 15 and 16 for supplying power from an external source are drawn out from each terminal 122.

[0019] In this example, the ceramic heater 171 has a through hole 171h in the axial direction L, and the liquid W introduced from the outside through the inlet 103 passes through the through hole 171h and is discharged from the outlet 105 through the internal space 100i along the flow direction F. The liquid W is then heated while in contact with the outer surface of the ceramic heater 171 along the axial direction L, and then flows to the outlet 105. In this example, the outlet 105 is positioned closer to the rear end of the cylindrical portion 101. Even if the liquid W overheats and forms bubbles near the high-temperature heating element 17a at the tip of the ceramic heater 171, gravity will cause it to float towards the rear end, making it easier for it to escape to the outside through the outlet 105.

[0020] Meanwhile, the interior 109 of the circuit housing section 110 houses lead wires 15 and 16, as well as various circuit boards. Various external wiring is also routed into the interior 109 of the circuit housing section 110.

[0021] Next, the configuration of the ceramic heater will be explained with reference to Figures 3 and 4. As shown in Figure 3, the ceramic heater 171 has a heating element 17h that generates heat when an external current is applied via lead wires 15, 16 and electrode pads 17p. The heating element 17h has a heating section 17a at its tip, which is formed by arranging a conductor in the direction of the axis L to create a heating pattern, and a pair of lead sections 17b that are drawn out from both ends of the heating section 17a towards the rear end.

[0022] More specifically, as shown in Figure 4, the heating element 17h has a heating portion 17a, two lead portions 17b, and an electrode pattern 17c formed at the rear ends of both lead portions 17b, and this heating element 17h is sandwiched between two ceramic green sheets 17s1 and 17s2. Alumina is used as the ceramic green sheet. Tungsten or rhenium, etc., are used for the heating portion 17a and lead portions 17b. Two electrode pads 17p are formed on the surface of the ceramic green sheet 17s2 (see Figure 3), and the electrode pattern 17c is connected to the electrode pads 17p by through holes to form a laminate of ceramic green sheets.

[0023] Furthermore, by wrapping this laminate around a rod-shaped ceramic substrate 17g, mainly composed of alumina, with the ceramic green sheet 17s2 facing outwards, and firing it, a ceramic heater 171 can be manufactured in which each ceramic green sheet 17s1 and 17s2 becomes a ceramic sheet 17s and is wrapped around the outer circumference of the ceramic substrate 17g, integrating them into one unit. In this example, the ceramic substrate 17g is cylindrical with a through hole 171h in the center, but it may also be solid.

[0024] Here, when winding the laminate onto the ceramic substrate 17g, the ends of the laminate along the axis L are wound with a gap between them. For this reason, a slit 17v, which is a concave groove along the axis L, is formed as a non-heating part in the winding portion on the outer surface of the ceramic heater 171. Therefore, when viewing the radial cross-section of the ceramic heater 171, the heating element 17a is embedded in the ceramic heater 171 in the form of an end ring, and a slit 17v, which is a non-heating element, is formed between the two ring ends 17e of the heating element 17a.

[0025] Next, with reference to Figures 5 and 6, the configuration of the liquid heating device 200 will be described in more detail. Figure 5 is an exploded perspective view of the area around terminal 122 of the liquid heating device 200, and Figure 6 is a cross-sectional view along line BB in Figure 5. Figure 5 is an exploded perspective view of the area around terminal 122 of the liquid heating device 200, and Figure 6 is a cross-sectional view along line BB in Figure 5.

[0026] As shown in Figure 5, each of the terminal housing sections 121a and 121b contains one terminal 122 (two in total), a spring 124, and a retaining section 126. Each terminal 122 is made of a round metal rod and has a large-diameter flange portion 121v in the center. While copper, brass, nickel, etc., are preferable for each terminal 122, other materials with excellent electrical conductivity are acceptable. The spring 124 is positioned radially outward from the flange portion 121f of each terminal 122, and the radially inward end of the spring 124 engages with the flange portion 121f. On the other hand, the radially outward end of the spring 124 engages with the radially inward plate portion 126b1 of the retaining portion 126. The holding portion 126 has plate portions 126b1 and 126b on the radially inner and outer sides, respectively, with a small-diameter cylindrical neck portion 126n positioned between the plate portions 126b1 and 126b. In addition, lead holes 126h for inserting lead wires 15 and 16 run through the holding portion 126 along its radial direction.

[0027] Then, the terminals 122, springs 124, and retaining parts 126 are inserted from the radially outward direction into the first openings 121h1 and 121h2 of the terminal housings 121a and 121b, respectively, and the retaining parts 126 are locked to the terminal housings 121a and 121b by a stopper 128, which will be described later. As a result, the repulsive force of the spring 124 held between the plate portion 126b1 of the holding portion 126 and the flange portion 121f of each terminal 122 causes the radially inward end portion 122s of each terminal 122 to be pressed radially inward and pressed against each of the electrode pads 17p.

[0028] As a result, the electrode pad 17p and the terminal 122 are electrically connected. Here, since the electrode pad 17p and the terminal 122 (its end 122s) are simply connected by pressure contact, complicated work such as brazing is unnecessary, and the electrical connection between the electrode pad 17p and the terminal 122 can be made simple and reliable. Furthermore, if, for example, a spring terminal is used for the electrode pad 17p, such as those commonly used in gas sensors, where the folded portion of a metal piece is elastically bent and connected to the electrode pad 17p, the spring terminal may scrape and drag the electrode pad 17p when the electrode pad 17p (ceramic heater 171) is inserted in the longitudinal direction of the spring terminal. In this case, electrode material is scraped from the electrode pad 17p and adheres to the outer surface of the ceramic heater 171, causing electrical conductivity and resulting in a leak. However, the present invention has the advantage of preventing such dragging. The contact pressure required for stable electrical connection between the electrode pad 17p and the terminal 122 can be adjusted, for example, by adjusting the spring force of the spring 124.

[0029] Furthermore, the core wires of each lead wire 15 and 16 are connected to the radially outer end of each terminal 122 by crimping or the like, and crimp terminals 15t or the like are connected to the ends of each lead wire 15 and 16. In this example, each terminal housing section 121a and 121b has two rectangular through holes 121v opening on its rear-end facing surface. The stopper 128 is a clip that is roughly U-shaped and has a pair of arms that expand elastically. Then, after inserting each holding portion 126 into the terminal housing portions 121a and 121b from the radially outer side, each stopper 128 is inserted through the insertion hole 121v toward the tip in the axial direction L, at which point the arms of the stopper 128 grip the neck portion 126n of the holding portion 126, locking the holding portion 126 to the terminal housing portions 121a and 121b. In other words, the radial movement of the holding portion 126 is restricted by the contact of each stopper 128 with the plate portions 126b1 and 126b.

[0030] Thus, the flow channel member 100 and the holding part 126 are separate components, and by using a stopper 128 that is separate from the holding part 126, the holding part 126 can first be pressed radially inward to compress the spring 124 radially, and then the holding part 126 can be locked in place with the stopper 128, making it easier to press each terminal 122 against the electrode pad 17p.

[0031] Furthermore, as shown in Figure 7, in this example, when viewed from the direction of axis L, the ends 122s of each terminal 122 are arranged at equal intervals on the circumference of the same virtual circle C. Specifically, two terminals 122 are arranged opposite each other on the circumference of the virtual circle C at a 180° angle. In this way, the resultant force P of the radially inward pressing force of each terminal 122 is canceled out at the center of the virtual circle C, and a resultant force is generated in a predetermined direction at the center of the virtual circle C, which suppresses bending stress and the like acting on the ceramic heater 171. Here, the end portion 122s is the end portion of the terminal 122 that is in contact with the electrode pad 17p. For example, if there are three terminals, each terminal will be positioned on the circumference of the virtual circle at an angle of 120°.

[0032] Furthermore, as shown in Figure 7, in this example, the end face 122s of the terminal 122 is flat, and the outer surface of the electrode pad 17p is curved so as to be convex radially outward. This ensures that the protrusion of the electrode pad 17p makes reliable contact with the flat surface which is the end face 122s of the terminal 122, thereby making the electrical connection between the electrode pad 17p and the terminal 122 more reliable.

[0033] The present invention is not limited to the embodiments described above, and it goes without saying that it extends to various modifications and equivalents that fall within the spirit and scope of the present invention. For example, the shape and arrangement of the liquid heating device and ceramic heater are not limited. The liquid heating device may have one ceramic heater or two or more. The flow channel member may consist of multiple members, and a holding portion may be pre-formed on a part of the flow channel member, and this member with the holding portion may be joined to the other members of the flow channel member. The stopper holds Department This is not limited to those that are secured by piercing the inside, but also includes retaining Department The stopper may also press against the radially outward-facing surface. [Explanation of Symbols]

[0034] 17a Heat-generating part 17p electrode pads 100 Flow channel member 100i interior space 103 Inlet 105 Outlet 121h1, 121h2 1st opening 122 terminals 122s terminal (one) end 124 Springs 126 Holding part 128 Stopper 171 Ceramic Heater 200 Liquid heating equipment L axis C Virtual Yen W liquid

Claims

1. A flow path member having an internal space through which liquid flows, and an inlet and outlet communicating with the internal space, A liquid heating device comprising: a ceramic heater having a heating element extending in the axial direction and generating heat when energized, and two or more electrode pads arranged on the outer surface and electrically connected to the heating element, and mounted in the internal space of the flow channel member, wherein the liquid is heated by at least the outer surface of the ceramic heater during the process in which the liquid is introduced from the inlet and flows through the internal space to the outlet, The electrode pad is positioned outside the internal space. Furthermore, it has two or more terminals, one end of which is pressed against each of the electrode pads and electrically connected, A spring that presses the terminal radially toward the electrode pad, A retaining portion that locks the radially outer end of the spring, Equipped with, The flow channel member and the holding part are separate components. The holding portion is inserted from the radially outer side into the first opening of the flow channel member, which faces radially outward. The system further includes a stopper that is locked to the aforementioned flow channel member, A liquid heating device characterized in that the stopper engages with the holding portion.

2. The liquid heating apparatus according to claim 1, characterized in that, when viewed from the axial direction, the ends of the terminals are arranged at equal intervals on the circumference of the same virtual circle.

3. The liquid heating apparatus according to claim 1 or 2, characterized in that the end face of the end of the terminal is flat and the outer surface of the electrode pad is curved so as to be convex radially outward.

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