JP2013238552A - Liquid level sensor, bath device and heat source machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level sensor capable of more accurately detecting a water level of a bathtub, and a bath device and a heat source machine having the liquid level sensor.SOLUTION: A liquid level sensor is provided with a pressure detection member and a temperature compensation IC on the front face side of a print substrate 31. The print substrate 31 is provided with through holes 48, 50 penetrating both sides thereof at a position where the pressure detection member is arranged and at a position where the temperature compensation IC is arranged. The through holes 48, 50 are subjected to metal plating inside thereof and around openings, and the pressure detection member and the temperature compensation IC contact the front face side of the print substrate 31. On the rear face side of the print substrate 31, the metal plating is connected to a wiring pattern part 52 for heat transfer.

Description

The present invention relates to a liquid level sensor. The liquid level sensor of the present invention is suitable as a water level sensor that detects the water level of a bathtub or a remaining fuel sensor that detects the remaining amount of liquid fuel.
Moreover, this invention relates to the bath apparatus which detects the water level of a bathtub with a liquid level sensor.
Furthermore, the present invention relates to a heat source device that detects a liquid level of liquid fuel by a liquid level sensor.

Bath devices having a function of dropping hot water into a bathtub or reheating hot water are widely used.
This type of bath apparatus often includes a water level sensor and monitors the water level of the bathtub. And when the hot water in the bathtub decreases, the hot water is automatically dropped.
Therefore, if the water level sensor breaks down, the water level in the bathtub cannot be detected accurately, the drop amount becomes excessive and hot water overflows from the bathtub, or the drop amount becomes excessive and the amount of hot water becomes insufficient. There is a problem.

By the way, the water level sensor uses a float to directly detect the height of the water surface, or transmits light to detect the height of the water surface. There are known ones that use a capacitance-type pressure sensor that is regarded as a change, and those that use a pressure sensor using a diffusion type semiconductor strain gauge.
Many water level sensors employed in bath equipment use a pressure sensor using a diffusion type semiconductor strain gauge.
A water level sensor using a pressure sensor measures the internal pressure of a pipe communicating with a bathtub and detects the water level from a pressure head based on the internal pressure.
That is, a water level sensor using a pressure sensor has a member that deforms due to pressure such as a diaphragm, and further includes a detection member that detects the amount of deformation of the diaphragm or the like. The detection member is, for example, a strain gauge, and its electrical characteristics such as electrical resistance change according to deformation.

A water level sensor that uses a pressure sensor has a smaller outer shape than a sensor that uses floating. In addition, the water level sensor that uses the pressure sensor does not directly detect the liquid level, so the detection unit is located away from the bathtub or the ground level of the detection unit is different from the ground level of the detection unit. It does not matter.
Therefore, it can be said that a pressure sensor is most suitable as a water level sensor used for a bath apparatus.

However, the water level sensor using the pressure sensor has a drawback that the output fluctuates depending on the ambient temperature. That is, the pressure sensor uses a detection member such as a strain gauge, but the output of these detection members changes depending on the ambient temperature. Therefore, the pressure sensor needs to correct the output (temperature compensation) according to the ambient temperature.
Patent Document 1 discloses a pressure sensor having a temperature compensation function.
The pressure sensor disclosed in Patent Document 1 includes a temperature compensating element. In the pressure sensor disclosed in Patent Document 1, one package body covers the temperature compensation element and the strain gauge so that the ambient temperature surrounding the temperature compensation element is equal to the ambient temperature surrounding the strain gauge. It is designed like this.

Japanese Patent No. 3043344

As described above, the pressure sensor disclosed in Patent Document 1 has been devised so as to be equal to the ambient temperature surrounding the strain gauge and the like, and can accurately detect the water level of the bathtub as compared with the conventional one. it can.
However, there is a market demand for more accurately detecting the water level in the bathtub, and further improvements are desired.
The present invention aims to meet the above requirements, and develops a liquid level sensor capable of more accurately detecting the water level of a bathtub, etc., and a bath apparatus and a heat source apparatus including the liquid level sensor. It is an object to do.

In order to solve the above-described problems, the present inventors have studied the characteristics of the liquid level sensor (pressure sensor) of the prior art and the special characteristics of the bath apparatus.
First, the characteristics of the liquid level sensor of the prior art are examined. The liquid level sensor of the prior art performs accurate temperature compensation in an environment where the ambient temperature changes slowly, and accurately detects the liquid level. be able to.

However, it has been found that the accuracy of the liquid level detection target is not accurate when the temperature of the liquid level detection target liquid changes abruptly or when the temperature of the liquid level detection target liquid is significantly different from the air temperature.
That is, since the liquid level sensor of the prior art (Patent Document 1) only covers the temperature compensation element and the strain gauge by a single package body, the heat between the detection unit having the strain gauge and the temperature compensation element is merely covered. Transmission only takes place indirectly via air. For this reason, in the liquid level sensor of the prior art, heat transfer between the detection unit having the strain gauge and the temperature compensating element is performed by air convection, so that it takes time for the temperatures of the two to become equal.
For this reason, when the temperature of the liquid subject to liquid level detection changes, the ambient temperature of the temperature compensation element cannot follow the temperature change of the liquid, and there is a difference between the temperature of the detection unit and the temperature of the temperature compensation element. It will occur.

  In addition, strain gauges and the like are strongly affected by the temperature of the liquid for which the liquid level is to be detected, and the elements and temperature compensation elements are strongly affected by the air temperature. However, an error occurred in the detected water level.

On the other hand, considering the peculiarity of the bath device, the water level sensor is used to detect the water level of the bathtub in the bath device, but the temperature of the hot water in the bathtub naturally changes.
Moreover, the temperature of the hot water in the bathtub and the outside air temperature are often different.
Furthermore, in a bath device, hot water supply or reheating is performed by burning a burner or the like, but when the burner is burning, if the temperature in the bath device is high and the burner is not ignited, the bath device The temperature inside is low.
As described above, the bath apparatus is under severe conditions for the pressure sensor, and it is difficult to accurately detect the water level.
That is, when the water level sensor of the prior art is applied to a bath apparatus, the strain gauge or the like is strongly influenced by the temperature of the hot water in the bathtub, whereas the temperature compensating element is strongly influenced by the outside air temperature or the heat dissipation of the burner. For this reason, a temperature difference occurs between the two, and temperature compensation cannot be performed appropriately.

Therefore, the present inventors have considered to eliminate the temperature difference between the portion where the strain gauge or the like is installed and the temperature compensating element by utilizing solid heat conduction.
In the invention according to claim 1 completed based on this idea, a pressure sensor and a temperature compensation unit are arranged on a substrate on which a wiring pattern is drawn, and the temperature compensation unit includes a temperature sensor, and outputs the pressure sensor. In the liquid level sensor for temperature compensation, the substrate is provided with a wiring pattern for heat transfer that connects an installation site of the temperature compensation unit and a part of the pressure sensor. is there.

Here, the wiring pattern is not limited to a flat pattern, but includes a three-dimensional pattern. That is, a structure in which a multilayer structure is formed through through holes or the like can be said to be a wiring pattern including through holes or the like.
The liquid level sensor of the present invention includes a wiring pattern for heat transfer that connects an installation site of the temperature compensation unit and a part of the pressure sensor. That is, heat can be transferred between the pressure sensor and the temperature compensation unit via the heat transfer wiring pattern. Since the wiring pattern for heat transfer is of course solid, the heat transfer uses solid heat conduction.
When heat transfer is performed using a solid such as a wiring pattern for heat transfer, heat transfer efficiency is dramatically improved compared to the case where heat transfer is simply performed by air convection (conventional method). Time-dependent malfunctions in functions are also greatly reduced.
As described above, in the present invention, the temperature difference between the pressure sensor and the temperature compensation unit can be made uniform reliably and efficiently by the wiring pattern for heat transfer, so that the water level detection accuracy of the liquid level sensor is dramatically improved. Can be improved.

  According to a second aspect of the present invention, the temperature compensation unit is constituted by an IC having a built-in temperature sensor, the IC has a package constituting an outer shell, and the installation site is a site where the IC package is installed. The liquid level sensor according to claim 1, wherein:

  According to the present invention, the IC package constituting the pressure sensor and the temperature compensation unit is connected by the wiring pattern for heat transfer. Thereby, there is no temperature difference between the temperature on the temperature compensation unit side and the temperature on the pressure sensor side, and the detection accuracy of the temperature sensor in the temperature compensation unit can be further improved.

  According to a third aspect of the present invention, the temperature compensator is constituted by an IC having a built-in temperature sensor, and the heat transfer wiring pattern is directly or thermally conductive on a package constituting the outline of the IC. The liquid level sensor according to claim 1, wherein the liquid level sensor is in indirect contact with each other.

  According to the present invention, the package constituting the outline of the IC constituting the pressure sensor and the temperature compensation unit is connected directly or indirectly by the wiring pattern for heat transfer. Thereby, there is no temperature difference between the temperature on the temperature compensation unit side and the temperature on the pressure sensor side, and the detection accuracy of the temperature sensor in the temperature compensation unit can be further improved.

The invention according to claim 4 is characterized in that the liquid level sensor according to any one of claims 1 to 3 is incorporated, and the water level of the hot water in the bathtub can be detected by the liquid level sensor. It is a bath device.

  The bath apparatus of the present invention can accurately detect the level of hot water in the bathtub. That is, as described above, even if a temperature difference is formed between the pressure sensor that is greatly affected by the temperature change of the hot water and the temperature compensation unit that is less affected by the temperature change of the hot water, Since the heat transfer wiring pattern can make the temperature on the temperature compensation unit side and the temperature on the pressure sensor side uniform, detection errors due to temperature differences can be made difficult to occur.

  The invention according to claim 5 is a heat source machine that includes a liquid fuel tank that stores liquid fuel, and that burns with the liquid fuel supplied from the liquid fuel tank, and is according to any one of claims 1 to 3. This is a heat source device that has a built-in liquid level sensor and can detect the fuel level in the liquid fuel tank by the liquid level sensor.

  According to the heat source apparatus of the present invention, as described above, since a detection error due to a temperature difference between the pressure sensor and the temperature compensation unit is unlikely to occur, the detection accuracy of the remaining amount of liquid fuel can be improved.

  In the liquid level sensor, the bath apparatus, and the heat source apparatus of the present invention, a part of the pressure sensor and the temperature compensation unit are connected by a wiring pattern for heat transfer, and therefore detection due to a temperature difference between the pressure sensor and the temperature compensation unit. It is difficult for errors to occur, and the level of hot water or the remaining amount of liquid fuel can be accurately detected.

It is a piping system diagram of the bath apparatus of the embodiment of the present invention. FIG. 2 is a perspective view of a water level sensor and an attachment joint used in the bath apparatus of FIG. 1. It is a disassembled perspective view of the water level sensor of FIG. It is sectional drawing of the water level sensor and attachment joint which are employ | adopted with the bath apparatus of FIG. It is a perspective view of the pressure detection unit built in the water level sensor of FIG. It is a conceptual diagram explaining the layer structure of the board | substrate of the pressure detection unit of FIG. FIG. 6 is a layout diagram showing an arrangement of elements and the like on the substrate of the pressure detection unit of FIG. 5. It is a top view which shows the surface side wiring pattern of the board | substrate of the pressure detection unit of FIG. It is explanatory drawing which abbreviate | omitted a part of surface side wiring pattern of FIG. 8, and clarified the installation site | part. It is explanatory drawing which observed the back surface side wiring pattern of the board | substrate of the pressure detection unit of FIG. 5 from the same direction as the front surface side wiring pattern of FIG. It is explanatory drawing which accumulated the back surface side wiring pattern shown in FIG. 10 on the installation site | part shown in FIG. FIG. 6 is an explanatory diagram illustrating layers of a pressure detection member and a temperature compensation IC, a front surface side wiring pattern, an insulating substrate, and a back surface side wiring pattern of the pressure detection unit of FIG. 5. (A) is a front view of IC for temperature compensation, (b) is a side view, (c) is a bottom view. It is a conceptual diagram explaining the laminated constitution of the board | substrate of the pressure detection unit employ | adopted by other embodiment of this invention. It is explanatory drawing which shows the wiring pattern of the intermediate | middle layer of the pressure detection unit employ | adopted by other embodiment of this invention. It is explanatory drawing which shows schematic structure of the heat-source equipment of this invention, and shows the state where kerosene fully remains in a kerosene tank. It is explanatory drawing which shows schematic structure of the heat-source equipment of this invention, and shows the state with little remaining amount of kerosene in a kerosene tank.

Embodiments of the present invention will be further described below.
The bath apparatus 1 of this embodiment incorporates the combustion apparatus 2 of the 1 can 2 water channel type like FIG.

  The bath apparatus 1 includes a hot water supply circuit 3 and a reheating circuit (circulation piping) 4. A drop channel 5 is provided between the two.

The reheating circuit (circulation piping) 4 forms a recirculation flow path 6 including a bathtub 7, a bath return flow path 11 for returning hot water from the bathtub 7 side to the reheating heat exchanger 10, and reheating A bath-out channel 12 for feeding hot water from the heat exchanger 10 side to the bathtub 7 side is provided.
The bath return channel 11 is provided with a water level sensor 20 and the like.
The water level sensor 20 detects the water level of the bathtub 7, and is specifically a pressure sensor.

The water level sensor 20 is attached to the bath return channel 11 by a dedicated joint 24 as shown in FIG.
The external shape of the water level sensor 20 is as shown in FIG. 2, and a mounting flange 22 is provided on one surface of the main body 21. The mounting flange 22 has arm portions 23 protruding in four directions, and the arm portions 23 are each provided with screw holes 25 (six in FIG. 2).

  A pressure introducing outer tube 26 protrudes from the center of the mounting flange 22. An O-ring 27 is disposed on the flange 22 and at the base of the pressure introducing outer tube 26.

A pressure detection unit 30 is built in the main body 21 as shown in FIG.
The pressure detection unit 30 includes a printed circuit board 31 and a pressure detection member 32, a temperature compensation IC 33, and other elements.
Here, the printed board 31 is a known double-sided board, and conductive foils 36 and 37 such as copper foil are laminated on both sides of an insulating plate 35 such as a bakelite as shown in FIG. 6, and wiring is performed by a known printing technique and etching technique. Patterns 40 and 41 are formed.
That is, the printed circuit board 31 has the surface-side conductive foil 36 on one surface of the insulating plate 35, and the surface-side wiring pattern 40 is formed on the surface-side conductive foil 36. Further, a back side conductive foil 37 is provided on the other surface of the insulating plate 35, and a back side wiring pattern 41 is formed on the back side conductive foil 37.

The printed circuit board 31 is appropriately provided with a through hole, and a conductor is plated in the through hole, and a part of the front surface side wiring pattern 40 and a part of the back surface side wiring pattern 41 are formed by the plating. It is connected.
That is, the printed circuit board 31 has a three-dimensional wiring pattern composed of a front surface side wiring pattern 40, a back surface side wiring pattern 41, and a conductor connecting them.

As shown in FIGS. 3 and 5, the pressure detecting member 32 has a pressure introducing inner tube 45 protruding from the main body block 43. The pressure introducing inner tube 45 is inserted into the pressure introducing outer tube 26 as shown in FIG. 4 and communicates with the pressure introducing outer tube 26.
The main body block 43 includes a member 49 that is deformed by pressure such as a diaphragm or a bellows, and includes a detection member (not shown) that detects the amount of deformation of the member 49 that is deformed, such as a diaphragm. The detection member is, for example, a strain gauge, and its electrical characteristics such as electrical resistance change according to deformation. The detection member applies a predetermined voltage and outputs a change in resistance as a change in voltage.
In the pressure detection member 32 employed in this embodiment, six terminals 44 a, 44 b, 44 c, 44 d, 44 e, 44 f protrude from the main body block 43.

The temperature compensation IC 33 is an IC in which a temperature sensor 46 (FIGS. 7 and 12) is incorporated, and has a package 47 that constitutes an outline, and an integrated circuit (not shown) is incorporated in the package 47.
The package 47 is square in plan view, and four terminals 54 protrude from each side.

Further, a metal thin plate 58 is provided on the back side of the package 47 as shown in FIG.
That is, the package 47 of the temperature compensation IC 33 has the same design as a known IC, and is made of black plastic. A thin metal plate 58 is attached to the back side of the plastic package 47 (the surface facing the front side of the printed circuit board 31) with an adhesive or the like.
The metal thin plate 58 is in the center of the package 47, and its area is about a quarter of the area of the back side of the package 47. It is recommended that the area of the metal thin plate 58 be 1/6 or more and 1/2 or less of the area on the back side.
This thin plate 58 is originally provided in order to secure the mounting strength of the temperature compensating IC 33 in the assembly process to the main body 21 and is electrically an island shape independent of any pattern wiring. It is a member. In the present embodiment, as will be described later, a heat transfer wiring pattern is connected to the thin plate 58 of the package 47.
As the material of the thin plate 58, a material having high thermal conductivity such as copper, copper alloy, aluminum, aluminum alloy or the like is recommended.

The temperature compensation IC 33 functions as a temperature compensation unit, and has a function of correcting a voltage signal output from a detection unit (not shown) of the pressure detection member 32 based on a temperature detected by the temperature sensor 46. .
That is, a program including a correction formula is written in the temperature compensation IC 33, and temperature compensation is performed on the voltage signal output from the detection unit (not shown).

The pressure detection member 32 and the temperature compensation IC 33 are arranged on the printed board 31 as shown in FIG. As apparent from a comparison between the layout of FIG. 7 and the front-side wiring pattern 40 of FIG. 8, the printed circuit board 31 includes a pressure detection member installation portion 15 in which the pressure detection member 32 is installed and a temperature compensation IC 33. The IC installation part 16 to be installed is formed.
FIG. 9 shows only the main part extracted from the surface side wiring pattern 40 of FIG. 7 and clarifies the two installation parts 15 and 16.

As described above, the front-side wiring pattern 40 and the back-side wiring pattern 41 are formed on the printed board 31.
That is, the surface side wiring pattern 40 has six pressure detection member plating portions 12 (a, b, c, d, e, f) for connecting the terminals of the pressure detection member 32 as shown in FIGS. Is provided.
Here, one of the six pressure sensing member plating portions 12 (a, b, c, d, e, f) has a printed board 31 as shown in FIGS. A through-hole 48 is provided in the front. Plating is applied to the inside of the through hole 48, the periphery of the opening on the front surface side of the through hole 48, and the periphery of the opening on the back surface side. Plating is a metal layer and naturally has high thermal conductivity. In the present embodiment, the plating in the through hole 48 and the plating around the opening are the three-dimensional portion 18 of the heat transfer wiring pattern, and are a part of the heat transfer wiring pattern. That is, the plating in the through hole 48 and the plating around the opening are members that contribute to heat conduction.

Furthermore, the surface side wiring pattern 40 is provided with 16 plating portions 38 for connecting the terminals of the temperature compensation IC 33. That is, the plating portion group including four pads is arranged in a square shape.
In the present embodiment, the IC installation part 16 is provided with a through hole 50. The through hole 50 penetrates the front and back surfaces of the printed circuit board 31, and plating is applied to the inside of the through hole 50, the periphery of the opening on the front surface side of the through hole 50, and the periphery of the opening on the back surface side. Plating is a metal layer and naturally has high thermal conductivity. In the present embodiment, the plating in the through-hole 50 and the plating around the opening are the three-dimensional portion 28 of the heat transfer wiring pattern and a part of the heat transfer wiring pattern. That is, the plating in the through hole 48 and the plating around the opening are members that contribute to heat conduction.

On the other hand, a back side wiring pattern 41 is formed on the back side of the printed circuit board 31.
The back surface side wiring pattern 41 constitutes the entire ground line, but as shown in FIG. 10, the region including the back surface side of the IC installation portion 16 is isolated by an annular insulating groove 51 and is used for heat transfer. A wiring pattern portion (back surface side) 52 is formed. That is, the heat transfer wiring pattern portion (back surface side) 52 is an island-shaped region electrically isolated from other regions.
A part of the heat transfer wiring pattern portion 52 hangs on the back side of the IC installation portion 16 and includes the above-described through hole 50.
As described above, since the inside of the through hole 50 is plated, and the periphery of the opening on the back surface side of the through hole 50 is also plated, the heat transfer wiring pattern portion (back surface side) 52 is provided. A part of is connected to the surface side through plating in the through hole 50. In other words, the heat transfer wiring pattern portion 52 is connected to the front surface side as the solid portion 28 of the heat transfer wiring pattern.

Further, a part of the heat transfer wiring pattern portion (back surface side) 52 is hung on the pressure detection member installation portion 15 and includes the above-described through hole 48.
As described above, since plating is applied in the through hole 48 and around the opening on the surface side of the through hole 48 and around the opening on the back surface side, a part of the heat transfer wiring pattern portion (back surface side) 52 is provided. Is communicated with the pressure detection member installation portion 15 on the surface side through plating in the through hole 48. That is, the heat transfer wiring pattern portion (back surface side) 52 is connected to the front surface side by using plating (the solid portion 18 of the heat transfer wiring pattern) as a heat conducting member.
Thus, in this embodiment, a series of heat transfer wiring patterns is formed by the three-dimensional portion 28 of the heat transfer wiring pattern, the heat transfer wiring pattern portion 52 on the back surface side, and the three-dimensional portion 18 of the heat transfer wiring pattern. Is formed.

A pressure detection member 32 and a temperature compensation IC 33 are attached to the printed circuit board 31 in a layout as shown in FIG. That is, the pressure detection member 32 is installed in the pressure detection member installation section 15, and each terminal of the pressure detection member 32 is soldered to the pressure detection member plating section 12.
Similarly, a temperature compensation IC 33 is installed in the IC installation section 16, and a terminal of the temperature compensation IC 33 is soldered to the plating section 38.

In the present embodiment, as described above, the temperature compensation IC 33 is installed in the IC installation section 16, and the back side of the package 47 of the temperature compensation IC 33 is in direct contact with the printed circuit board 31. Accordingly, the metal thin plate 58 provided on the back surface side of the package 47 of the temperature compensation IC 33 is also in direct contact with the printed circuit board 31.
Further, as described above, the IC mounting portion 16 is provided with the through hole 50, and plating is performed around the opening of the through hole 50. Therefore, the plating around the opening of the through hole 50 is directly performed. In particular, the temperature compensation IC 33 is in contact with the back surface side of the package 47. More specifically, the plating around the opening of the through hole 50 is in direct contact with the metal thin plate 58 provided on the back side of the package 47 of the temperature compensating IC 33.
Further, since the inside of the through hole 50 is also plated, and the periphery of the opening on the back side is also plated, the back side (the thin metal plate 58) of the package 47 is interposed through the plating layer. It is in contact with the heat transfer wiring pattern portion 52 on the back side.

On the other hand, in the other part of the heat transfer wiring pattern portion 52 on the back surface side, there is a through hole 48 as described above, and communicates with the pressure detection member installation portion 15 through plating in the through hole 48. . Therefore, on the back surface side of the package 47 of the temperature compensation IC 33, as shown in FIG. 11, the plated portion around the opening on the surface side of the through hole 50, the plating in the through hole, and the plating around the opening on the back surface side of the through hole 50. , A heat transfer wiring pattern portion 52, a plating portion around the opening on the back side of the through hole 48, a plating of the through hole 48, a plating portion around the opening on the surface side of the through hole 48, and a plating portion 12 d for the pressure detection member And connected to the terminal of the pressure detection member 32.
Assuming that the plated portions are the three-dimensional portions 18 and 28 of the heat transfer wiring pattern, the back surface side (metal thin plate 58) of the package 47 of the temperature compensation IC 33 is the three-dimensional portion 28 of the heat transfer wiring pattern and the back surface side. It is connected to the terminal of the pressure detection member 32 via the heat transfer wiring pattern portion 52 and the three-dimensional portion 18 of the heat transfer wiring pattern.
That is, the temperature compensation IC 33 is constituted by a series of heat transfer wiring patterns constituted by the solid portion 28 of the heat transfer wiring pattern, the heat transfer wiring pattern portion (back side) 52, and the solid portion 18 of the heat transfer wiring pattern. And the pressure detection member 32 are connected.

In this way, the temperature compensation IC 33 is connected to the pressure detection member 32 through these heat transfer paths, and heat is transferred between the temperature compensation IC 33 and the pressure detection member 32 by heat conduction between solids. To do.
Therefore, in this embodiment, the temperature difference between the temperature compensation IC 33 and the pressure detection member 32 is small.

  Therefore, even if the temperature of the hot water flowing through the bath return channel 11 changes, the temperature of the temperature compensating IC 33 follows this. As a result, the temperature sensor built in the temperature compensation IC 33 can detect a temperature equivalent to the ambient temperature of the pressure detection member 32, and correct temperature correction is performed.

  That is, the water level sensor 20 is attached to the bath return channel 11 by a dedicated joint 24 as shown in FIG. 2, and the hot water in the bath return channel 11 passes through the pressure introduction outer tube 26 to the pressure introduction inner tube 45. The member 49 to be deformed such as a diaphragm is pressed. Then, the deformation of the diaphragm or the like is detected by a detection member (not shown) such as a strain gauge and output as a change in voltage. The output is temperature compensated by the temperature compensation IC 33.

Here, the detecting member such as a strain gauge is close to the hot water, and the temperature thereof is close to the temperature of the hot water.
On the other hand, the temperature compensating IC 33 is located away from the hot water. However, in the present embodiment, the temperature compensation IC 33 is connected to the pressure detection member 32 by a series of heat transfer wiring patterns, and heat conduction between solids between the temperature compensation IC 33 and the pressure detection member 32. Therefore, the temperature difference between the detection member such as a strain gauge and the temperature compensation IC 33 is small. In particular, in the present embodiment, a metal thin plate 58 is provided on the back side of the temperature compensation IC 33, and heat conducted from the detection member side such as a strain gauge is diffused widely over the entire back side of the temperature compensation IC 33. Therefore, the temperature difference between the detection member such as a strain gauge and the temperature compensation IC 33 is small.
Therefore, the temperature compensation IC 33 appropriately compensates the temperature, and an accurate water level is detected.

  In the embodiment described above, a double-sided board is adopted as the printed board 31, but a multilayer printed board 55 as shown in FIG. 14 may be adopted. For example, in the case of using a four-layer substrate having a front side conductive foil 60, a first intermediate conductive foil 61, a second intermediate conductive foil 62, and a back side conductive foil 63 as shown in FIG. The aforementioned heat transfer wiring pattern portion 52 is provided on either or both of the conductive foil 61 and the second intermediate conductive foil 62.

In addition, when a multilayer substrate as shown in FIG. 14 is employed, it is possible to use a single conductive foil only for heat transfer.
When a single conductive foil is used only for heat transfer, it is desirable to increase the area of the heat transfer wiring pattern portion. For example, as shown in FIG. 15, the entire area of the substrate may be a heat transfer wiring pattern portion 70.
As shown in FIG. 15, when the entire region of the substrate is used as the heat transfer wiring pattern portion, the entire substrate functions as a heat transfer layer.
In the embodiment described above, a part of the heat transfer wiring pattern is directly brought into contact with the package 47 of the temperature compensating IC 33, but indirectly through an adhesive or the like having high thermal conductivity. You may let them.

  Although the bath apparatus 1 of the above embodiment incorporated the combustion apparatus 2 of the one can two water channel type, this invention is not limited to this type, A two can two water channel type or two cans Another type of combustion device such as a three-water channel type may be incorporated.

In the embodiment described above, the liquid level sensor of the present invention is used as a water level sensor, but the present invention is not limited to this application.
For example, the liquid level sensor of the present invention may be used in a hot water supply device (heat source device) that uses liquid fuel such as kerosene as shown in FIGS. In the hot water supply apparatus shown in FIGS. 16 and 17, the liquid level sensor of the present invention is used as a sensor for detecting the remaining amount of kerosene.
That is, the hot water supply apparatus includes a kerosene tank (liquid fuel tank), and burns a burner (not shown) by introducing kerosene from the kerosene tank.
In the present embodiment, a liquid level sensor 71 is attached to a pipe for introducing kerosene from a kerosene tank (liquid fuel tank).
When the remaining amount of kerosene in the kerosene tank falls below a certain amount, a message to that effect is displayed on the remote controller.

DESCRIPTION OF SYMBOLS 1 Bath apparatus 2 Combustion apparatus 6 Circulation flow path 7 Bathtub 10 Reheating heat exchanger 11 Bath return flow path 12 Bath return flow path 18 Solid part 20 of heat transfer wiring pattern Water level sensor (liquid level sensor)
28 Three-dimensional part 30 of heat transfer wiring pattern Pressure detection unit 31, 55 Printed circuit board 32 Pressure detection member 46 Temperature sensor 48 Through hole 50 Through hole 70 Heat transfer wiring pattern part (rear surface side)
71 Liquid level sensor

Claims (5)

In a liquid level sensor in which a pressure sensor and a temperature compensation unit are arranged on a substrate on which a wiring pattern is drawn, and the temperature compensation unit includes a temperature sensor and temperature compensation is performed on the output of the pressure sensor.
The liquid level sensor, wherein the substrate is provided with a heat transfer wiring pattern that connects an installation site of the temperature compensation unit and a part of the pressure sensor.   The temperature compensation unit is configured by an IC having a built-in temperature sensor, the IC has a package forming an outer shell, and the installation site is a site where the package of the IC is installed. The liquid level sensor according to 1.   The temperature compensation unit is configured by an IC having a built-in temperature sensor, and the wiring pattern for heat transfer is in direct contact with a package constituting the outline of the IC directly or through a heat conducting member. The liquid level sensor according to claim 1.   A bath apparatus comprising the liquid level sensor according to any one of claims 1 to 3 and capable of detecting a water level of hot water in a bathtub by the liquid level sensor. A heat source machine comprising a liquid fuel tank for storing liquid fuel, and combusting with the liquid fuel supplied from the liquid fuel tank, comprising the liquid level sensor according to any one of claims 1 to 3, A heat source apparatus, characterized in that a liquid level of a fuel in a liquid fuel tank can be detected by a liquid level sensor.

Images