WO2024009726A1

WO2024009726A1 - Heating device for vehicle

Info

Publication number: WO2024009726A1
Application number: PCT/JP2023/022301
Authority: WO
Inventors: 隆仁中村; 啓暢土方; 康志浅野
Original assignee: 株式会社デンソー
Priority date: 2022-07-06
Filing date: 2023-06-15
Publication date: 2024-01-11

Abstract

This heating device for a vehicle comprises: a light source (4) or a sensor (21); a lens (5); a heater (6); and a hydrophilic coating (7). The light source (4) emits light towards the outside of a vehicle (1). Alternatively, the sensor (21) transmits and receives electromagnetic waves. The lens (5) is provided in a light emission direction in which the light is emitted from the light source (4), or in a transmission/reception direction in which the electromagnetic waves are transmitted and received by the sensor (21), and the lens (5) transmits the light or the electromagnetic waves. The heater (6) is provided to the lens (5) and generates heat by energization. The hydrophilic coating (7) is applied to the outermost surface, on the outside-air side, of the lens (5) or the heater (6).

Description

Vehicle heater device

Cross-reference to related applications

This application is based on Japanese Patent Application No. 2022-109100 filed on July 6, 2022 and Japanese Patent Application No. 2023-30221 filed on February 28, 2023. The contents herein are incorporated by reference.

The present disclosure relates to a vehicle heater device.

In recent years, with the evolution of in-vehicle electronics, the development of advanced driver-assistance systems (ADAS) for automobiles has been remarkable, and autonomous driving is becoming a reality. Japan's Ministry of Land, Infrastructure, Transport and Tourism aims to gradually raise the level of autonomous driving from the current level 2 (i.e., autonomous driving function under specific conditions) to reach level 5, which is fully autonomous driving, between 2025 and 2030. want to be. However, sensor products have a problem in that the sensitivity of the sensor decreases in adverse environments (for example, snowfall, freezing, heavy rain, and dense fog). Therefore, a vehicle heater device is known that uses a heater to warm the lens of a headlight or sensor device mounted on a vehicle, thereby preventing ice and snow from accumulating on the lens and ensuring the optical function or sensor function. .
Patent Document 1 describes a heater device in which a heating wire is provided on the lens of a headlight. This Patent Document 1 describes a technique for preventing fogging on the inner surface of the lens by using a coating provided on the inner side of the lens. Furthermore, a technique is described in which a heating wire provided on a lens is bonded and held by coating. Additionally, techniques are described for reducing or eliminating fog, droplets, and ice on lenses by increasing the thermal conductivity of heating wires through coatings. Note that in Patent Document 1, the heating wire is called a conductive trace (i.e., a conductive wire).

US Patent Application 2021/0388966A1 Specification

However, when a heater such as a heating wire and a coating are provided on the inside of the lens of a headlight as in Patent Document 1, snow builds up on the surface of the lens on the outside air side (hereinafter simply referred to as "lens surface") during snowfall. The water melted by the heat of the heater stays on the surface of the lens due to frictional force. This makes it difficult for the heat from the heater to transfer to the snow that accumulates on top of the water on the surface of the lens, making it impossible for the heat from the heater to melt the snow, and eventually the water on the lens absorbs heat from the snow and freezes. It turns into ice. If snow accumulates on the lens starting from the ice, the amount of light emitted from the headlight's light source to the outside of the lens decreases, making it impossible to ensure the optical function of the headlight.

On the other hand, it is also possible to increase the amount of heat generated by the heater to melt all the snow that has accumulated on the lens. However, if this is done, the amount of heat generated by the heater will correspond to the latent heat of the snow accumulated on the lens, and the power consumed by the heater will increase.

By the way, as a countermeasure against snow accumulation, it is also possible to apply a water-repellent coating or hydrophobic coating to the surface of the lens to prevent snow from accumulating on the lens. Note that both the water-repellent coating and the hydrophobic coating are coatings that have the property of repelling water. Specifically, a hydrophobic coating refers to one in which the contact angle between the coating surface and water is 40° to 90°, and a water-repellent coating refers to one in which the contact angle between the coating surface and water is 90° or more.

However, according to experiments conducted by the disclosers of the present disclosure, both water-repellent and hydrophobic coatings can prevent snow from accumulating on the surface of the lens in the case of dry snow, but in the case of wet snow. It was found that once snow is deposited due to a collision, snow accumulates from that point.

An object of the present disclosure is to provide a vehicle heater device that can reduce power consumed by the heater in order to ensure optical function or sensor function in wet snow.

According to one aspect of the present disclosure, a vehicle heater device includes a light source or sensor, a lens, a heater, and a hydrophilic coating. The light source or sensor emits light or transmits and receives electromagnetic waves to the outside of the vehicle. The lens is provided in the irradiation direction of light emitted from the light source or in the transmission/reception direction of electromagnetic waves transmitted and received by the sensor, and transmits light or electromagnetic waves. The heater is provided on the lens and generates heat when energized. The hydrophilic coating is applied to the surface of the lens or heater that is closest to the outside air.

According to this, when snow adheres to a lens coated with a hydrophilic coating, when the part of the snow on the lens side is melted by the heat of a heater, the melted water is transferred to the surface of the lens (i.e. , the surface of the area where the hydrophilic coating was applied) and forms a film of water. The film of water reduces the frictional force between the surface of the lens and the snow, and the water cannot remain on the surface of the lens, and the snow, together with the film of water, slides off the lens under its own weight. This makes it possible to irradiate light from the light source to the outside of the lens, or to transmit and receive electromagnetic waves from the sensor to the outside of the lens. In this way, this vehicle heater device does not melt all of the snow with the heat generated by the heater, but melts only the portion of the snow on the lens side, thereby eliminating the snow and reducing the power consumed by the heater.

According to another aspect of the present disclosure, a vehicle heater device includes a sensor, a cover member, a heater, and a hydrophilic coating. The sensor transmits and receives electromagnetic waves to the outside of the vehicle. The cover member is provided in the direction of transmission and reception of electromagnetic waves transmitted and received by the sensor, and transmits the electromagnetic waves. The heater is provided on the cover member and generates heat when energized. The hydrophilic coating is applied to the surface of the cover member or heater that is closest to the outside air.

According to this, another aspect of the present disclosure also has the same effect as one aspect of the present disclosure.

Note that the reference numerals in parentheses attached to each component etc. indicate an example of the correspondence between that component etc. and specific components etc. described in the embodiments described later.

FIG. 1 is a perspective view of a vehicle equipped with a vehicle heater device according to a first embodiment. FIG. 1 is a sectional view of a vehicle heater device according to a first embodiment. FIG. 3 is a diagram showing a region coated with a hydrophilic coating when viewed in the direction of arrow III in FIG. 2, that is, when viewed from the front of the vehicle heater device. FIG. 3 is an explanatory diagram for explaining how snow attached to a lens slides off the lens together with a film of water. FIG. 3 is a diagram showing how snow attached to a lens is melted by the heat of a heater and becomes water, and the water is spread over the surface of the lens by a hydrophilic coating. FIG. 3 is a diagram showing how snow attached to a lens is melted by the heat of a heater and becomes water, and the water becomes bead-shaped water droplets on the surface of the lens due to a water-repellent or hydrophobic coating. Continuing from FIG. 6, it is a diagram showing a state in which snow is placed on bead-shaped water droplets. Continuing from FIG. 7, it is a diagram showing a state in which bead-shaped water droplets are absorbed heat by snow on top of the water droplets, freeze, and become ice. FIG. 3 is a sectional view of a vehicle heater device according to a second embodiment. FIG. 3 is a sectional view of a vehicle heater device according to a third embodiment. It is a sectional view of the vehicle heater device concerning a 4th embodiment. It is a side view of the front part of the vehicle in which the vehicle heater device of the reference example is mounted. It is a sectional view of the vehicle heater device concerning a 5th embodiment. It is a table showing test conditions for a snow-shedding property evaluation test. It is a graph showing the state of snow accretion in a snow-shedding property evaluation test. 2 is a table showing the results of a snow-shedding evaluation test for test specimens coated with various coatings, and the contact angle and sliding angle of the various coatings. This is a table showing excerpts of Mighty Luck GII (registered trademark) and Hydrophilic Material A from the snow-shedding evaluation test results. It is an explanatory diagram explaining the mechanism of snow accretion and sliding. It is a graph showing the relationship between the sliding angle to water and the snow adhesion force for various coating materials. FIG. 2 is an explanatory diagram for explaining an FT-NIR analysis method. It is a table showing FT-NIR analysis conditions. It is a graph showing a method for distinguishing between water and ice by FT-NIR analysis. It is a graph showing the results of freezing delay measurements for Mighty Luck GII (registered trademark) and hydrophilic material A. It is a table showing the results of a snow melting evaluation test for each sample.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that in each of the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals, and the description thereof will be omitted.

(First embodiment)
A first embodiment will be described with reference to the drawings. As shown in FIG. 1, the vehicle heater device is configured as a headlight 2 of a vehicle 1, various sensors, etc., and is mounted on the vehicle 1. In the first embodiment, a vehicle heater device configured as a headlight 2 of a vehicle 1 will be described. In addition, in each drawing, the up-down direction, the front-back direction, and the left-right direction of the vehicle 1 are shown by arrows.

As shown in FIG. 2, a headlight 2 as a vehicle heater device according to the first embodiment includes a housing 3, a light source 4, a lens 5, a heater 6, a hydrophilic coating 7, and the like. Note that in the drawings, the shape, size, thickness, etc. of each component are schematically shown for convenience of explanation.

The housing 3 is made of resin or the like, and forms the outer shell of the headlight 2 together with the lens 5. A reflecting mirror 8 and the like are provided inside the casing 3.

The light source 4 is provided inside the housing 3 and emits light toward the outside of the vehicle 1. In FIG. 2, the light emitted from the light source 4 is schematically shown by a chain double-dashed line with reference numeral 9. In FIG. The light source 4 is composed of, for example, an LED lamp, an HID lamp, or a halogen lamp. LED is an abbreviation for light-emitting diode, and HID is an abbreviation for high intensity discharge. The light source 4 is an example of a "light source or sensor" described in the claims.

Although not shown in the drawings, various sensors may be installed inside the housing 3, for example, to detect objects in front of the vehicle. Examples of the various sensors include a sonar sensor, a millimeter wave radar sensor, a LIDAR sensor, and an image sensor. LIDAR is an abbreviation for Light Detection and Ranging or Laser Imaging Detection and Ranging.

The lens 5 is an outer lens provided in the light irradiation direction of the light source 4. The outer edge of the lens 5 is fixed to the housing 3. The lens 5 is formed of a material (eg, glass or resin) that transmits the light emitted from the light source 4. Further, when various sensors are provided within the housing 3, the lens 5 is formed of a material (eg, glass or resin) that transmits electromagnetic waves transmitted and received by the sensor.

Note that inside the lens 5, an internal space 10 is formed by the housing 3 and the lens 5. The internal space 10 is a space formed in a hermetically closed state or a semi-sealed state. Note that the sealed state refers to a state in which the air in the internal space 10 and the outside air are cut off, and the semi-sealed state refers to a state in which the circulation between the air in the internal space 10 and the outside air is restricted, but a slight circulation is allowed. A state in which

The heater 6 is an electric heater that is provided on the lens 5 and generates heat when energized. In the first embodiment, the heater 6 is provided on the surface of the lens 5 on the light source 4 side (hereinafter referred to as "inner surface of the lens 5"). Therefore, the lens 5 prevents the heater 6 from being damaged by collisions with foreign objects from the outside.

The heater 6 of this embodiment is provided on substantially the entire inner surface of the lens 5. However, the heater 6 is not limited thereto, and the heater 6 may be provided in an area that includes an area where the light source 4 is projected onto the lens 5 in the main direction of the light emitted from the light source 4, and that covers 50% or more of the entire surface area of the lens 5. It may be.

The heater 6 is configured using at least one of carbon nanotubes (hereinafter referred to as "CNT"), heating wires, or indium tin oxide (hereinafter referred to as "ITO"), for example. CNT is an abbreviation for carbon nanotube, and ITO is an abbreviation for indium tin oxide. When constructing the heater 6 using CNTs, the heater 6 is a transparent conductive film in which CNTs are arranged in a transparent thin film, and is attached to the inner surface of the lens 5.

As shown in FIGS. 2 and 3, the hydrophilic coating 7 is applied to the surface of the lens 5 on the outside air side. Note that in this specification, the surface of the lens 5 on the outside air side is sometimes referred to as the "surface of the lens 5" or "the outer surface of the lens 5." The hydrophilic coating 7 is configured so that water adhering to the surface of the lens 5 (that is, the surface of the portion of the lens 5 where the hydrophilic coating 7 is applied) spreads along the surface and flows down. . Specifically, the hydrophilic coating 7 is one in which the contact angle between the coating surface and water is 40° or less. Although the thickness of the hydrophilic coating 7 is illustrated in the drawings for convenience of explanation, the actual thickness of the hydrophilic coating 7 is, for example, a thin film of about several nanometers to several tens of micrometers. Therefore, in this specification, "the surface of the lens 5" is sometimes used to mean the surface of the portion of the lens 5 on which the hydrophilic coating 7 is applied, in addition to the surface of the lens 5 itself.

The hydrophilic coating 7 of this embodiment is applied to substantially the entire surface of the lens 5. However, the hydrophilic coating 7 is not limited thereto, and includes an area where the light source 4 is projected onto the lens 5 in the main direction of the light emitted from the light source 4, and an area that is 50% or more of the entire surface area of the lens 5. It may be applied to In that case, the hydrophilic coating 7 and the heater 6 are preferably provided so as to overlap in the thickness direction of the lens 5 in a range of 50% or more of the entire surface area of the lens 5.

Next, the significance of applying the hydrophilic coating 7 to the surface of the lens 5 will be explained.

FIG. 4 shows the behavior of the wet snow 12 attached to the lens 5. As shown in FIG. 4, when wet snow 12 adheres to the lens 5, when the part of the wet snow 12 on the lens 5 side is melted by the heat of the heater 6, the melted water is absorbed by the action of the hydrophilic coating 7. It spreads along the surface of the lens 5 and becomes a film of water 13. Then, the water film 13 reduces the frictional force between the surface of the lens 5 and the wet snow 12, and the water cannot stay on the surface of the lens 5, and as shown by arrow A, the water film 13 At the same time, the wet snow 12 slides off the lens 5 due to its own weight. In this way, the vehicle heater device can remove the wet snow 12 by not melting all the wet snow 12 by the heat generated by the heater 6, but by melting only the portion of the wet snow 12 on the lens 5 side.

Next, the difference between the case where the hydrophilic coating 7 is applied to the surface of the lens 5 and the case where a water repellent coating or a hydrophobic coating (hereinafter referred to as "water repellent or hydrophobic coating 14") is applied will be explained. Note that in FIGS. 5 to 8, the thickness of each coating is not shown because the thickness of each coating is, for example, about several nm to several tens of μm.

FIG. 5 is a diagram showing how snow attached to the surface of the lens 5 is melted by the heat of the heater 6 and becomes water when the hydrophilic coating 7 is applied to the surface of the lens 5. As shown in FIG. 5, in the case of the hydrophilic coating 7, water that melts snow due to the heat of the heater 6 spreads along the surface of the lens 5 due to the action of the hydrophilic coating 7. In FIG. 5, the distance D1 between the surface of the lens 5 and the surface of the water film 13 on the opposite side of the lens 5 (hereinafter referred to as "height D1 of the water film 13") is indicated by an arrow.

On the other hand, FIGS. 6 to 8 show how snow accumulates on the surface of the lens 5 when the water-repellent or hydrophobic coating 14 is applied to the surface of the lens 5. Note that FIGS. 6 to 8 show how snow accumulates over time.

First, FIG. 6 is a diagram showing how snow attached to the surface of the lens 5 coated with the water-repellent or hydrophobic coating 14 is melted by the heat of the heater 6 and becomes water. As shown in FIG. 6, in the case of the water-repellent or hydrophobic coating 14, the contact angle between the coating surface and water is larger than that of the hydrophilic coating 7, so the water melted by the heat of the heater 6 can interact with each other due to surface tension. They combine to form bead-shaped water droplets 15. In FIG. 6, the distance D2 between the surface of the lens 5 and the surface of the water droplet 15 on the opposite side of the lens 5 (hereinafter referred to as "height D2 of the water droplet 15") is indicated by an arrow. Here, the height D2 of the water droplet 15 shown in FIG. 6 is higher than the height D1 of the water film 13 shown in FIG. 5.
Therefore, as shown in FIG. 7 following FIG. 6, when snow 12 is further placed on top of the water droplets 15, the heat of the heater 6 becomes difficult to be transferred to the snow 12, so the heat of the heater 6 is used to cover the snow 12. It cannot be completely dissolved.
As shown in FIG. 8 following FIG. 7, when more snow 12 is on the ground, the amount of heat absorbed by the accumulated snow 12 becomes larger than the amount of heat generated by the heater 6, and eventually the water droplets on the lens 5 freeze and turn into ice. It turns out to be 16. Then, snow will accumulate starting from the ice 16.

In this way, when the water-repellent or hydrophobic coating 14 is applied to the surface of the lens 5, once the snow 12 collides with the surface of the lens 5 and lands on it, the snow 12 will accumulate from that point as a starting point. When snow 12 accumulates on the surface of the lens 5, the amount of light emitted from the light source 4 of the headlight 2 to the outside of the lens 5 decreases, making it impossible to ensure the optical function of the headlight 2. Further, when a sensor is installed in the headlight 2, if electromagnetic waves from the sensor cannot be transmitted or received outside the lens 5, the sensor function cannot be ensured.

On the other hand, the vehicle heater device of the first embodiment can have the following configuration and effects.
(1) In the vehicle heater device of the first embodiment, a hydrophilic coating 7 is applied to the outside air side surface of the lens 5 on which the heater 6 is provided.
According to this, when wet snow 12 adheres to the lens 5, the part of the wet snow 12 on the lens 5 side is melted by the heat of the heater 6, and the water film 13 spreads along the surface of the lens 5. The wet snow 12 together with the water film 13 can be slid off the lens 5 by its own weight. This makes it possible to irradiate light from the light source 4 to the outside of the lens 5, or to transmit and receive electromagnetic waves from the sensor to the outside of the lens 5. In this way, this vehicle heater device can reduce the power consumed by the heater 6 by melting only the portion of the snow on the lens 5 side, rather than melting all the snow by the heat generated by the heater 6.

(2) In the first embodiment, the heater 6 is provided on the inner surface of the lens 5. Thereby, the lens 5 prevents the heater 6 from being damaged due to collision of foreign objects from the outside.

(3) In the first embodiment, the heater 6 is configured using at least one of CNT, heating wire, or ITO. According to this, the heater 6 may be made of CNT, heating wire, or ITO.

(4) In the first embodiment, the hydrophilic coating 7 includes an area where the light source 4 is projected onto the lens 5 in the main direction of the light emitted from the light source 4, and 50% of the entire surface area of the lens 5. It may be set within the above range.
If the hydrophilic coating 7 is provided in such a range, snow can be removed from the area in front of the light source 4 when the heater 6 is activated, and the optical function of the headlight 2 can be ensured.

(Second embodiment)
A second embodiment will be described. The second embodiment differs from the first embodiment in that the configurations of the heater 6 and the hydrophilic coating 7 are changed, and other aspects are the same as the first embodiment, so the differences from the first embodiment are as follows. I will only explain.

As shown in FIG. 9, in the second embodiment, the heater 6 is provided on the surface of the lens 5 on the outside air side. Therefore, the heater 6 can efficiently transfer heat to the snow.
Furthermore, in the second embodiment, the hydrophilic coating 7 is applied to the surface of the heater 6 on the outside air side. That is, when the heater 6 is formed of a transparent conductive film, the hydrophilic coating 7 is applied to the surface of the transparent conductive film on the outside air side. On the other hand, when the heater 6 is formed of a heating wire, the hydrophilic coating 7 is applied to the surface of the heating wire on the outside air side, and is also applied to the surface of the lens 5 exposed between the heating wires. Ru.

The vehicle heater device of the second embodiment described above can also have the same effects as the first embodiment.
Furthermore, in the second embodiment, the heater 6 is provided on the surface of the lens 5 on the outside air side. According to this, the heater 6 can efficiently transmit heat to the snow.

(Third embodiment)
A third embodiment will be described. In the first and second embodiments described above, the headlight 2 is used as the vehicle heater device. On the other hand, in the third embodiment, a vehicle heater device configured as a sensor device 20 mounted on the vehicle 1 will be described.

As shown in FIG. 10, a sensor device 20 as a vehicle heater device of the third embodiment includes a housing 3, a sensor 21, a lens 5, a heater 6, a hydrophilic coating 7, and the like. The sensor device 20 is used, for example, in advanced driver-assistance systems (ADAS). Note that the sensor device 20 may be mounted on the vehicle 1 in any direction, including front and rear, top and bottom, left and right, and diagonally, and there is no limitation on the mounting position.

The housing 3 is made of resin, metal, or the like, and forms the outer shell of the sensor device 20 together with the lens 5.

The sensor 21 is provided inside the housing 3 and transmits electromagnetic waves to the outside of the vehicle 1 and receives electromagnetic waves from the outside of the vehicle 1. In FIG. 10, the region of electromagnetic waves transmitted from the sensor 21 is schematically shown with a chain double-dashed line labeled 22. In FIG. The sensor 21 is configured by, for example, a sonar sensor, a millimeter wave radar sensor, a LIDAR sensor, an image sensor, or the like. The sensor 21 is an example of a "light source or sensor" described in the claims.

The lens 5 is provided in the direction in which the sensor 21 transmits and receives electromagnetic waves. The outer edge of the lens 5 is fixed to the housing 3. The lens 5 is formed of a material (for example, resin or glass) that transmits electromagnetic waves transmitted and received by the sensor 21. Note that the lens 5 may be, for example, black so as to block visible light. The lens 5 is sometimes called a housing window or a cover member.

Note that in FIG. 10, an internal space 10 is formed by the housing 3 and the lens 5. However, the sensor device 20 is not limited to such a configuration. For example, the sensor device 20 may have a configuration in which the housing 3 and the lens 5 are placed apart from each other and the internal space 10 is not formed. For example, the lens 5 may be an emblem provided at the front of the vehicle, and the housing 3 and the sensor 21 may be arranged at the rear of the vehicle with respect to the emblem.

The heater 6 is an electric heater that is provided on the lens 5 and generates heat when energized. Note that in the third embodiment, the heater 6 is provided on the inner surface of the lens 5. Therefore, the lens 5 prevents the heater 6 from being damaged by collisions with foreign objects from the outside. The configuration of the heater 6 is substantially the same as that described in the first and second embodiments, except that it does not need to be transparent.

The heater 6 of the third embodiment is provided on substantially the entire inner surface of the lens 5. However, the heater 6 is not limited thereto, and the heater 6 is provided in an area that includes the area where the sensor 21 is projected onto the lens 5 in the main direction of the electromagnetic waves transmitted from the sensor 21, and that covers 50% or more of the entire surface area of the lens 5. It may be.

The hydrophilic coating 7 of the third embodiment is applied to substantially the entire surface of the lens 5. However, the hydrophilic coating 7 is not limited thereto, and includes an area where the sensor 21 is projected onto the lens 5 in the main direction of electromagnetic waves transmitted from the sensor 21, and an area that is 50% or more of the entire surface area of the lens 5. It may be applied to In that case, the hydrophilic coating 7 and the heater 6 are preferably provided so as to overlap in the thickness direction of the lens 5 in a range of 50% or more of the entire surface area of the lens 5.

The vehicle heater device of the third embodiment described above can also have the same effects as the first and second embodiments.

(Fourth embodiment)
A fourth embodiment will be described. The vehicle heater device of the fourth embodiment is also configured as a sensor device 20 mounted on the vehicle 1, as in the third embodiment.

As shown in FIG. 11, in the fourth embodiment, the heater 6 included in the vehicle heater device is provided on the surface of the lens 5 on the outside air side.
Moreover, the hydrophilic coating 7 is applied to the surface of the heater 6 on the outside air side. That is, when the heater 6 is formed of a transparent conductive film, the hydrophilic coating 7 is applied to the surface of the transparent conductive film on the outside air side. On the other hand, when the heater 6 is formed of a heating wire, the hydrophilic coating 7 is applied to the surface of the heating wire on the outside air side, and is also applied to the surface of the lens 5 exposed between the heating wires. Ru.
Other than that, the configuration of the vehicle heater device of the fourth embodiment is the same as that described in the third embodiment.

The vehicle heater device of the fourth embodiment described above can also achieve the same effects as those of the first to third embodiments.

(Reference example)
Next, a vehicle heater device as a reference example will be described. The vehicle heater device of the reference example is configured as a headlight 2, similar to that described in the first and second embodiments.

However, as shown in FIG. 12, in the vehicle 1 in which the vehicle heater device of this reference example is installed, the front bumper 22, which is disposed below the vehicle with respect to the headlights 2, is moved further forward of the vehicle than the headlights 2. It sticks out. Furthermore, the surface of the front bumper 22 that faces upward of the vehicle (hereinafter referred to as "bumper top surface 23") is a nearly horizontal flat surface. Depending on the shape of the front bumper 22, snow 12a that has slipped off the lens 5 of the headlight 2 may accumulate on the upper surface 23 of the bumper, which may impede the optical function or sensor function of the headlight 2. The configuration of the fifth embodiment described below is effective for the problem of this reference example.

(Fifth embodiment)
A fifth embodiment will be described. The fifth embodiment is intended to solve the problems described in the reference example above.

As shown in FIG. 13, in addition to the configuration described in the first and second embodiments, the vehicle heater device of the fifth embodiment also includes a bumper heater 61 and a bumper hydrophilic coating for the front bumper 22. It is equipped with 71.

The bumper heater 61 is provided at a portion of the front bumper 22 at least below the lens 5 of the headlight 2 in the vehicle width direction. Note that at least a portion below the vehicle with respect to the lens 5 means a portion below the vehicle at least within the range of the lens 5 in the vehicle width direction. Further, the bumper heater 61 shown in FIG. 13 is provided over the entire front bumper 22 in the vehicle vertical direction. However, the present invention is not limited thereto, and the bumper heater 61 may be provided only in a region of the front bumper 22 that is above the center (that is, on the headlight 2 side) in the vehicle vertical direction. Alternatively, the bumper heater 61 may be provided only on the top surface 23 of the bumper, or only on the top surface 23 of the bumper and its surroundings.

Further, the bumper heater 61 shown in FIG. 13 is provided on a surface of the front bumper 22 that faces toward the front of the vehicle and a surface that faces toward the top of the vehicle. However, the bumper heater 61 is not limited thereto, and may be provided on the surface of the front bumper 22 facing toward the rear of the vehicle and the surface facing downward of the vehicle (that is, the back surface of the bumper). The bumper heater 61 is configured using at least one of CNT, heating wire, and ITO, for example.

The bumper hydrophilic coating 71 is applied on the bumper heater 61 provided on the front bumper 22. That is, the bumper hydrophilic coating 71 is provided at a portion of the front bumper 22 that is at least below the lens 5 of the headlight 2 in the vehicle width direction. Further, the bumper hydrophilic coating 71 shown in FIG. 13 is provided on the entire front bumper 22 in the vehicle vertical direction. However, the present invention is not limited thereto, and the bumper hydrophilic coating 71 may be provided only in a region of the front bumper 22 that is above the center (that is, on the headlight 2 side) in the vehicle vertical direction. Alternatively, the bumper hydrophilic coating 71 may be provided only on the top surface 23 of the bumper, or only on the top surface 23 of the bumper and its surroundings.

The structure of the bumper hydrophilic coating 71 is the same as that described in the first embodiment, etc., so that water adhering to the bumper surface (that is, the surface of the portion where the bumper hydrophilic coating 71 is applied) is It is constructed so that it spreads along the line and flows down.

The vehicle heater device of the fifth embodiment described above has the following configuration and the effects thereof.
The vehicle heater device of the fifth embodiment includes a bumper heater 61 and a bumper hydrophilic coating 71 that are applied to a portion of the front bumper 22 below the lens 5 of the vehicle.
According to this, even when snow accumulates on the front bumper 22, the portion of the snow on the bumper side is melted by the bumper heater 61 to form a film of water, and the snow along with the water film slides off the bumper due to its own weight and wind. It is possible to drop it. Therefore, this vehicle heater device can maintain the optical function of the headlight 2 or the sensor function of the sensor 21, and reduce the power consumed by the bumper heater 61.

(Modification 1 of the fifth embodiment)
As a first modification of the fifth embodiment, the vehicle heater device includes a bumper heater 61 provided in a portion of the front bumper 22 below the lens 5 of the vehicle, and does not include the bumper hydrophilic coating 71. You can also use it as According to this, even if snow that has slipped off the headlight lens 5 may accumulate on the front bumper 22, the snow is melted by the bumper heater 61 and the optical function of the headlight 2 or the sensor 21 is Functionality can be ensured.

(Modification 2 of the fifth embodiment)
As a second modification of the fifth embodiment, the vehicle heater device includes a bumper hydrophilic coating 71 applied to a portion of the front bumper 22 below the lens 5 of the vehicle, and does not include the bumper heater 61. You can also use it as According to this, even if snow that has slipped off the headlight lens 5 may accumulate on the front bumper 22, the bumper hydrophilic coating 71 prevents the snow from sliding off the front bumper 22 together with a film of water. It is possible. Therefore, the optical function of the headlight 2 or the sensor function of the sensor 21 can be ensured. Note that the water film may be formed by using water that has melted snow using the heat of the heater 6 provided on the lens 5 of the headlight 2.

(Evaluation test)
Hereinafter, a plurality of evaluation tests conducted by the disclosers of the present disclosure will be described.

(Snowfall evaluation test)
First, the snow shedding property evaluation test will be explained. The snow shedding property evaluation test is a test in which a plurality of test pieces were prepared with various coatings applied to each test piece, and the ease with which snow fell off with the various coatings was evaluated.

As shown in FIG. 14, the test piece used was made of aluminum A1050, had a size of 100 x 100 x 1 mm, and had a surface roughness of Rz 0.002 μm (that is, a mirror surface).
In the snow-shedding evaluation test, artificially produced wet snow was blown onto the coated surface of the test piece at a wind speed of 10 m/s at a 90° angle for 30 minutes in an environment at room temperature +1 to 2°C. The snow that was blown onto the test piece repeatedly adhered to the coated surface of the test piece and fell off.

FIG. 15 is a graph showing the state of snow accretion in the snow-shedding evaluation test. The vertical axis shows the thickness or mass of snow accumulation, and the horizontal axis shows time.
As shown in FIG. 15, when the test is started at time T1, the snow grows between time T1 and time T2 (that is, the snow growth time), and then falls due to its own weight at time T2. The period from time T2 to time T3 is a snow-free time in which no snow adheres to the test piece. After that, the snow grows again between time T3 and time T4 (that is, the snow growth time), and then falls due to its own weight at time T4. After repeating snow growth and snowfall multiple times, the test ends at time T5. In the snow shedding performance evaluation test, the weight of fallen snow, the number of times it fell, the height of snow accumulation, and the adhesion time were evaluated. Note that, depending on the test piece, there were some that did not receive snowfall or no snow accumulation time.

The results of each test piece in the snow-shedding evaluation test are shown in FIG. 16. In FIG. 16, the average snow weight is the average value of the snow weight for each snow growth time. The average snowfall height is the average value of the snowfall height for each snowfall growth time. The number of snow falls is the number of times snow fell within the test time (ie, 30 minutes). The average snow accretion time is the average value of the snow accretion growth time. The total weight of snowfall is the total weight of snow that fell during the test time. The average snow adhesion is the average weight of fallen snow divided by the area of the coated surface of the test piece. Note that the average snow adhesion force is expressed in Excel, and for example, 5.0E-03 represents 5.0×10 ⁻³ .

The contact angle with water (hereinafter referred to as "contact angle") is the angle formed by the contact area between the coating surface of the test piece and water. As mentioned above, in this specification, coatings with a contact angle of 40° or less are referred to as hydrophilic coatings, coatings with a contact angle of 40° to 90° are referred to as hydrophobic coatings, and coatings with a contact angle of 90° or more are referred to as hydrophobic coatings. It's called a water-repellent coating.

The sliding angle to water (hereinafter referred to as the "sliding angle") is the horizontal angle at which the pure water slides down when 10 microliters of pure water is dropped onto the coated surface of a test piece and the test piece is tilted. is the angle of the specimen with respect to In this specification, if the sliding angle is 10° or less, the coating surface is considered to have high sliding properties.

No. in the table of Figure 16. As shown in Fig. 11, hydrophilic material A had a much higher number of snowfalls than the other test pieces (10 times), the average snowfall time was short at 2.72 minutes, and the total weight of snowfall was small at 119.8g.

FIG. 17 shows No. 1 of the test pieces shown in the table of FIG. Mighty Luck GII (registered trademark) of No. 2 and No. 2 Mighty Luck GII (registered trademark). This is an excerpt of No. 11 hydrophilic material A. Mighty Luck GII (registered trademark) is a trade name of Nippon Paint Co., Ltd. Hydrophilic material A is a product name of Resonac Co., Ltd. The former name of Resonac Co., Ltd. was Showa Denko Materials Co., Ltd. FIG. 17 shows an image of the exterior after a 30-minute snow-shedding evaluation test. In this image, the snow appears white, and the areas where it has fallen appear black. In addition, in the image, the test piece is the part shown by the dashed line. In the image of Mighty Luck GII (registered trademark), it can be seen that the snow adhering to the test piece is continuous and extends downward in the direction of gravity. On the other hand, in the image of hydrophilic material A, it can be seen that the snowfall is divided into pieces.

Note that the sliding angle shown in FIGS. 16 and 17 is the sliding angle when 10 microliters of pure water is dropped onto the coating surface of the test piece. On the other hand, although not shown, when the test piece was coated with hydrophilic material A, the sliding angle when 30 microliters of pure water was dropped on the surface was less than 10°. Furthermore, when the test piece was coated with hydrophilic material A, the contact angle when 1 microliter of pure water was dropped onto the surface was 10°.

Here, the mechanism of snow accretion and sliding is shown in Figure 18. As shown in FIG. 18, when snow 12 at a temperature below freezing adheres to the surface of the coating 31 of the test piece 30, the snow 12 is melted water that melts at the interface with the test piece on the test piece whose temperature is the same as room temperature, +1 to 2°C. 32, and when snow 12 adheres to the melt water 32, it falls due to its own weight. Note that the melt water 32 is also called interfacial melt water. Although not shown, it is thought that if the snow 12 continues to adhere, the test piece cooled by the snow 12 will freeze the melted water, increasing the binding force with the snow and causing snow accretion. Therefore, in order to make it easier for snow to fall off, it is possible to make the properties of the coating so that melt water can easily slide off, and to make it difficult for melt water to freeze. The ease with which meltwater slides down was evaluated by the sliding angle to water, and the ability to fall snow was evaluated by the average snow adhesion force. As a result, it was found that the smaller the sliding angle to water, the smaller the snow adhesion force and the better the snow shedding performance. Therefore, it is considered that water sliding properties are necessary for snow shedding properties.

FIG. 19 is a graph showing the relationship between the sliding angle to water and the snow adhesion force for various coating materials. As shown by the broken line R in FIG. 19, there is a correlation between the sliding angle to water and the snow adhesion force. As shown in FIG. 19, it can be seen that, among hydrophilic coatings, hydrophilic material A has a very small sliding angle to water and a very small snow adhesion force.

Note that in the snow-shedding evaluation test described above, not only hydrophilic coatings but also water-repellent or hydrophobic coatings were tested. However, water-repellent or hydrophobic coatings are water-repellent or hydrophobic by making the surface uneven and creating a layer of air between the protrusions. Therefore, it is undesirable to use water-repellent or hydrophobic coatings for sensors and lights, also because electromagnetic waves or light will be dispersed. From this point of view, hydrophilic coatings are suitable for coatings used in sensors and lights because electromagnetic waves or light do not scatter.

(Freezing delay evaluation test)
Next, the freezing delay evaluation test will be explained. The freezing delay evaluation test is a test that evaluates the properties of various coating materials that make it difficult for melted water to freeze. In the freezing delay evaluation test, it was determined whether the interfacial melt water on the surface of the coating material was frozen or not using near-infrared spectroscopy, and the freezing delay effect was verified by the frost formation phenomenon.

Specifically, as shown in FIG. 20, in the freezing delay evaluation test, a test piece 30 coated with a coating 31 was placed on the low-temperature side of a Peltier element 34 and was incorporated into a near-infrared spectrometer, and Test piece 30 was cooled. Then, by cooling the test piece 30 with the Peltier element 34, water molecules 35 in the air were condensed to form condensed water 36 on the surface of the coating 31, and the time it took for the condensed water 36 to freeze was measured. FIG. 21 shows the analysis conditions of near-infrared spectroscopy in the freezing delay evaluation test.

Figure 22 shows a method for distinguishing between water and ice using near-infrared spectroscopy. As a result of analyzing condensed water and ice (specifically, frost), the peak wavelength of absorbance when there is water on the coating surface is 1460 nm, and the peak wavelength of absorbance when there is ice on the coating surface is 1492 nm. It was confirmed that there was a difference between

Next, as shown in FIG. 23, the freezing time during which the peak wavelength of water shifts to the peak wavelength of ice from the start of the freezing delay evaluation test was measured. As a result, when the coating material was Mighty Lac GII (registered trademark), the peak wavelength of absorbance shifted approximately 490 seconds after the start of the test. Therefore, when the coating material was Mighty Luck GII (registered trademark), the time from the start of the test until the interfacial melt water on the surface of the coating material turned into ice was about 490 seconds. On the other hand, when the coating material was hydrophilic material A, the peak wavelength of absorbance shifted approximately 760 seconds after the start of the test. Therefore, when the coating material was hydrophilic material A, the time from the start of the test until the interfacial melt water on the surface of the coating material turned into ice was about 760 seconds. This confirmed that hydrophilic material A had a longer freezing delay time than Mighty Luck GII (registered trademark). Therefore, it can be said that hydrophilic material A has excellent snow-shedding properties because it is difficult to freeze interfacial melt water on the coating surface. In addition, if the time from the start of the test until the interfacial melt water on the surface of the coating material becomes ice is approximately 500 seconds or more, it can be said that the hydrophilic coating has a longer freezing delay time than Mighty Luck GII (registered trademark). .

(Snow melting power consumption evaluation test)
Next, a snow melting power consumption evaluation test will be explained. In the snow melting power consumption evaluation test, test pieces made of various coating materials applied to polycarbonate (hereinafter referred to as "PC"), which is a base material commonly used in headlamp heaters, etc. The amount of electricity was measured.

This test was conducted under the conditions of an environmental temperature of -5°C, a wind speed of 20 km/h, a snowfall amount of 30 mm/h, and an impact angle of snow on the test piece surface of 90°.

As shown in FIG. 24, five samples were prepared as test pieces. Sample 1 is a PC, specifically a PS PRO plastic sheet manufactured by RS Components Co., Ltd. Sample 2 is a PC coated with a hard coat, and Acryking (registered trademark) manufactured by Mitsubishi Chemical Corporation was used as the hard coat. Sample 3 is a PC subjected to surface treatment, and Diabeam (registered trademark) manufactured by Mitsubishi Chemical Corporation was used for the surface treatment. Sample 4 is a PC surface treated, and for the surface treatment, Hydrophilic Material A manufactured by Resinac Co., Ltd. was used. Sample 5 is a PC subjected to surface treatment, and Optool (registered trademark) of Daikin Industries, Ltd. was used for the surface treatment.

Tests 1 to 4 and 6 were cold start tests, and tests 5, 7 to 9 were hot start tests. Note that Tests 4 and 5 were conducted consecutively, and Tests 6 to 8 were also conducted consecutively.

In the cold start test, when a predetermined power was applied to the sample while it was cooled and snow was blown onto the sample, the amount of power required to cause the snow to slide down was measured. In the table of FIG. 24, the x mark indicates that the snow did not slide down, and the ○ mark indicates that the snow did slide down. As a result, in Test 2, the hydrophilic material A of Sample 4 caused snow to slide down at the lowest power of 1347 W/m ² .

In the hot start test, when a predetermined power was applied to the sample while it was warm and snow was blown onto the sample, the amount of power required to cause the snow to slide down was measured. As a result, in Test 5, the hydrophilic material A of Sample 4 caused snow to slide down at the lowest power of 1257 W/m ² .

From this test result, it can be said that hydrophilic A is the most preferable coating material that can reduce the power consumption of the heater. Hydrophilic material A has hydrophilicity, as is clear from the above-mentioned snow-shedding evaluation test and freezing delay evaluation test, and also has characteristics such as water sliding properties and freezing delay characteristics.

(Other embodiments)
(1) In each of the above embodiments, the vehicle heater device is configured as the headlight 2 or sensor device 20 of the vehicle 1, but is not limited thereto, and is configured as a lighting device such as a tail lamp or turn signal lamp. You may.

(2) In the fifth embodiment and its modifications, the vehicle heater device is such that the front bumper 22 protrudes further toward the front of the vehicle than the headlights 2, and the upper surface 23 of the bumper is a nearly horizontal flat surface. Although explained, it is not limited to that. The vehicle heater device may include at least one of the bumper heater 61 and the bumper hydrophilic coating 71 regardless of the shape of the bumper of the vehicle 1 on which it is mounted.

(3) In the fifth embodiment and its modifications, the vehicle heater device includes the bumper heater 61 or the bumper hydrophilic coating 71 on the front bumper 22, but the present invention is not limited thereto. When the vehicle heater device is applied as a tail lamp, the rear bumper disposed below the tail lamp may include at least one of a bumper heater 61 and a bumper hydrophilic coating 71.

The present disclosure is not limited to the embodiments described above, and can be modified as appropriate. Furthermore, the above-described embodiments and parts thereof are not unrelated to each other, and can be combined as appropriate, except in cases where combinations are clearly impossible. Furthermore, in each of the above embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where it is specifically stated that they are essential or where they are clearly considered essential in principle. stomach. In addition, in each of the above embodiments, when numerical values such as the number, numerical value, amount, range, etc. of the constituent elements of the embodiment are mentioned, when it is clearly stated that it is essential, or when it is clearly limited to a specific number in principle. It is not limited to that specific number, except in cases where In addition, in each of the above embodiments, when referring to the shape, positional relationship, etc. of constituent elements, etc., the shape, It is not limited to positional relationships, etc.

(Perspective of this disclosure)
The present disclosure described above can be understood, for example, from the following viewpoints.
[First viewpoint]
In a vehicle heater device,
A light source (4) or sensor (21) that emits light or transmits and receives electromagnetic waves toward the outside of the vehicle (1);
a lens (5) that is provided in the irradiation direction of light emitted from the light source or in the transmission and reception direction of electromagnetic waves transmitted and received by the sensor, and that transmits light or electromagnetic waves;
a heater (6) that is provided on the lens and generates heat when energized;
A vehicle heater device comprising: a hydrophilic coating (7) applied to a surface of the lens or the heater that is closest to the outside air.
[Second viewpoint]
The vehicle heater device according to the first aspect, wherein the heater is provided on a surface of the lens on the light source side or the sensor side, or on a surface of the lens on the outside air side.
[Third viewpoint]
The vehicle heater device according to the first or second aspect, wherein the heater is configured using at least one of carbon nanotubes, heating wires, and indium tin oxide.
[Fourth viewpoint]
The hydrophilic coating is applied to an area where the light source is projected onto the lens toward the main direction of light emitted from the light source, or where the sensor is projected onto the lens toward the main direction of electromagnetic waves transmitted from the sensor. The vehicle heater device according to any one of the first to third aspects, which includes the projected region and is provided in a range of 50% or more of the entire surface area of the lens.
[Fifth viewpoint]
Any one of the first to fourth aspects, further comprising a bumper heater (61) that is provided at a portion of the front bumper (22) or the rear bumper of the vehicle at least below the lens with respect to the vehicle and generates heat when energized. The vehicle heater device described in .
[Sixth viewpoint]
The vehicle according to any one of the first to fourth aspects, further comprising a bumper hydrophilic coating (71) applied to at least a portion of the vehicle's front bumper or rear bumper below the lens. heater device.
[Seventh viewpoint]
a bumper heater that is provided at least in a portion of the front bumper or rear bumper of the vehicle below the vehicle with respect to the lens, and that generates heat when energized;
The vehicle according to any one of the first to fourth aspects, further comprising a bumper hydrophilic coating applied to a portion of the front bumper, the rear bumper, or the bumper heater that is located below the vehicle at least with respect to the lens. Vehicle heater device.
[Eighth viewpoint]
In a vehicle heater device,
a sensor (21) that transmits and receives electromagnetic waves to the outside of the vehicle (1);
a cover member (5) that is provided in the direction of transmission and reception of electromagnetic waves transmitted and received by the sensor and that transmits the electromagnetic waves;
a heater (6) that is provided on the cover member and generates heat when energized;
A vehicular heater device comprising: a hydrophilic coating (7) applied to a surface of the cover member or the heater that is closest to the outside air side.
[Ninth viewpoint]
The hydrophilic coating has a sliding mechanism in which the pure water slides down when 10 microliters of pure water is deposited on the surface of the hydrophilic coating and the angle of inclination of the surface of the hydrophilic coating with respect to the horizontal is set to 10 degrees or less. The vehicle heater device according to any one of the first to eighth aspects, which is water-based.
[Tenth viewpoint]
The above-mentioned hydrophilic coating was tested by placing a test piece with the hydrophilic coating on the low temperature side of a Peltier element, installing it in a near-infrared spectrometer, and turning on the Peltier element under the following test conditions. When the peak wavelength of absorbance is measured by spectroscopy, the time from the appearance of the peak wavelength of water at 1460 nm until the peak wavelength transitions to the peak wavelength of ice at 1492 nm is 500 seconds or more. The vehicle heater device according to any one of the first to ninth aspects.
However, as the test conditions, the voltage of the Peltier element is 12V, the temperature is 25°C, and the relative humidity is 50% RH.As the measurement conditions for the near-infrared spectroscopy, the measurement model is FT/IR-6700, and the The incident angle of near-infrared rays is 20°, the light source is halogen, the measurement range of the absorbance peak wavelength is 900 to 1700 nm, the resolution is 4 cm ^-1 , the integration is 7 times, the measurement interval is 10 seconds, and the measurement time is the peak wavelength of ice. This is until the height change at 1492 nm becomes small.

Claims

In a vehicle heater device,
A light source (4) or sensor (21) that emits light or transmits and receives electromagnetic waves toward the outside of the vehicle (1);
a lens (5) that is provided in the irradiation direction of light emitted from the light source or in the transmission and reception direction of electromagnetic waves transmitted and received by the sensor, and that transmits light or electromagnetic waves;
a heater (6) that is provided on the lens and generates heat when energized;
A vehicle heater device comprising: a hydrophilic coating (7) applied to a surface of the lens or the heater that is closest to the outside air.
The vehicle heater device according to claim 1, wherein the heater is provided on a surface of the lens on the light source side or the sensor side, or on a surface of the lens on the outside air side.
The vehicle heater device according to claim 1 or 2, wherein the heater is configured using at least one of carbon nanotubes, heating wires, and indium tin oxide.
The hydrophilic coating is applied to an area where the light source is projected onto the lens toward the main direction of light emitted from the light source, or where the sensor is projected onto the lens toward the main direction of electromagnetic waves transmitted from the sensor. The vehicle heater device according to claim 1 or 2, wherein the vehicle heater device is provided in a range that includes the projected area and covers 50% or more of the entire surface area of the lens.
The vehicle heater according to claim 1 or 2, further comprising a bumper heater (61) that is provided in a portion of the front bumper (22) or the rear bumper of the vehicle at least below the lens and generates heat when energized. Device.
The vehicle heater device according to claim 1 or 2, further comprising a bumper hydrophilic coating (71) applied to at least a portion of the front bumper or rear bumper of the vehicle below the lens.
a bumper heater that is provided at least in a portion of the front bumper or rear bumper of the vehicle below the vehicle with respect to the lens, and that generates heat when energized;
The vehicle heater device according to claim 1 or 2, further comprising a bumper hydrophilic coating applied to at least a portion of the front bumper, the rear bumper, or the bumper heater that is located below the lens of the vehicle.
In a vehicle heater device,
a sensor (21) that transmits and receives electromagnetic waves to the outside of the vehicle (1);
a cover member (5) that is provided in the direction of transmission and reception of electromagnetic waves transmitted and received by the sensor and that transmits the electromagnetic waves;
a heater (6) that is provided on the cover member and generates heat when energized;
A vehicular heater device comprising: a hydrophilic coating (7) applied to a surface of the cover member or the heater that is closest to the outside air side.
The hydrophilic coating has a sliding mechanism in which the pure water slides down when 10 microliters of pure water is deposited on the surface of the hydrophilic coating and the angle of inclination of the surface of the hydrophilic coating with respect to the horizontal is set to 10 degrees or less. The vehicle heater device according to claim 1, 2 or 8, which is water-based.
The above-mentioned hydrophilic coating was carried out by placing a test piece with the hydrophilic coating on the low temperature side of a Peltier element, installing it in a near-infrared spectrometer, turning on the power to the Peltier element under the following test conditions, and performing near-infrared spectroscopy. Claim: 1. The invention has freezing delay characteristics in which the time from the appearance of the peak wavelength of water at 1460 nm until the peak wavelength transitions to the peak wavelength of ice of 1492 nm is 500 seconds or more when the peak wavelength of absorbance is measured by the method. 9. The vehicle heater device according to 1, 2 or 8.
However, as the test conditions, the voltage of the Peltier element is 12V, the temperature is 25°C, and the relative humidity is 50% RH.As the measurement conditions for the near-infrared spectroscopy, the measurement model is FT/IR-6700, and the The incident angle of near-infrared rays is 20°, the light source is halogen, the measurement range of the absorbance peak wavelength is 900 to 1700 nm, the resolution is 4 cm -1 , the integration is 7 times, the measurement interval is 10 seconds, and the measurement time is the peak wavelength of ice. This is until the height change at 1492 nm becomes small.