AIR PURIFICATION DEVICE FOR VEHICLES
An ozone purification body supported on a vehicle component has manganese dioxide and activated carbon as ozone purification components. The mixing ratio (weight basis) of activated carbon and manganese dioxide is 4:1 to 1:4.
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The disclosure of Japanese Patent Application No. 2012-167181 filed on Jul. 27, 2012 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION1. Field of the Invention
The invention relates to an air purification device for vehicles, and more particularly to an air purification device for vehicles that allows purifying ozone in air.
2. Description of Related Art
Ozone, which is one cause of photochemical smog, is generated as a result of photochemical reactions of HC and NOx that are present in exhaust gas of automobiles and factories. Accordingly, suppressing ozone generation by reducing emissions of HC and NOx from automobiles is an effective way of preventing the occurrence of photochemical smog. Otherwise, direct purification of ozone in air is a conceivable method for preventing the occurrence of photochemical smog. The occurrence of photochemical smog can be prevented yet more effectively by purifying also ozone, as a product, in addition to aiming at reducing emissions of HC and NOx as reactants. Against this background, automobiles provided with an air purification device for vehicles that enables direct purification of ozone in air have been introduced in some regions, such as California. These air purification devices for vehicles are referred to, in particular, as direct ozone reduction (DOR) systems.
For instance, Published Japanese Translation of PCT Application No. 2002-514966 (JP-2002-514966 A) discloses such a DOR system in which a metal oxide such as manganese dioxide is supported on a vehicle component such as a radiator. The radiator is disposed at a site that comes into contact with air during vehicle travel, and manganese dioxide has the function of purifying the ozone present in air by being converted to another substance such as oxygen. Therefore, the DOR system of JP-2002-514966 A enables direct purification of ozone in air during vehicle travel. Further, JP-2002-514966 A discloses an ozone purification test that utilizes the above metal oxide, and an ozone purification test that utilizes activated carbon (AC), and indicates that AC can an catalyze a reduction reaction of ozone to O2.
Various materials, though not used in DOR systems, have been developed that rely on the ozone breakdown function of AC. For instance, Japanese Patent Application Publication No. 2011-104529 (JP-2011-04529 A) discloses the feature of using both manganese dioxide and AC in the form of a hazardous-substance removing material for eliminating ozone that is generated by electrophotographic devices such as laser printers, as well as formaldehyde and volatile organic compounds (VOC) released by recording paper. This hazardous substance removing material, which exploits the ozone breakdown function and VOC adsorption function of AC, and the formaldehyde breakdown function of manganese dioxide, is produced through impregnation of AC particles with manganese dioxide particles. Specifically, JP-2011-104529 A (examples) discloses the feature of setting the impregnation proportion of manganese dioxide to 5 wt % and 10 wt % with respect to the total of impregnated AC particles.
Devices have also been developed that resort to the ozone purification function of a material such as the one disclosed in JP-2011-104529 A. For instance, Japanese Patent Application Publication No. 11-33358 (JP-11-33358 A) discloses a deodorizer that has 10 wt % of AC, 26 wt % of alumina and 62 wt % of manganese dioxide. This deodorizer is developed for the purpose of decomposing and absorbing aldehydes, which are malodorous components. The deodorizer is used in combination with an ozone generator that is disposed upstream of the deodorizer. Specifically, ozone generated by the ozone generator is broken down by the deodorizer into active oxygen, and aldehydes are oxidized by the active oxygen and are adsorbed in the state of acetic acid.
Japanese Patent Application Publication No. 5-168854 (JP-5-168854 A), for instance, discloses a filter in which AC, as an adsorbent, is disposed downstream of an ozone purification body that utilizes manganese dioxide. This filter is developed in view of the fact that the ozone purification function of manganese dioxide is weaker at low temperature and at high humidity than at normal temperature. Further, JP-5-168854 A indicates that an ozone purification ratio can be maintained at a high level over long periods of time in experiments where the filter is used for treating ozone-containing air at a temperature of 5° C. and relative humidity of 100%. However, the reasons underlying such results in JP-5-168854 A are unclear.
Various materials have been developed that rely on functions, other than an ozone purification function, of manganese dioxide. For instance, Japanese Patent Application Publication No. 2006-289248 (JP-2006-289248 A) discloses a NOx purification material that is made up of a porous body of manganese dioxide that has a NOx breakdown function, and AC that supports palladium and that functions as a NO2 adsorbent. The content of the manganese dioxide porous body in this NOx purification material ranges preferably from 40 to 80 wt %.
For instance, Japanese Patent Application Publication No. 2006-271966 (JP-2006-271966) discloses an adsorbent for chemical filters that utilizes manganese oxide and graphite. The purpose of the adsorbent for chemical filters is to adsorb and remove oxidizing gases such as NOx and SOx.
An ozone purification function is exhibited not only by a metal oxide such as manganese dioxide, but also by AC, as in JP-2002-514966 A. Herein, the ozone purification function of AC is advantageous in that it is comparable to that of a metal oxide such as manganese dioxide, while, in addition, ozone can be purified in a normal temperature region (about 20° C.). The ozone purification function of manganese dioxide is weaker at low temperature and high humidity than at normal temperature, as indicated in JP-5-168854 A. Therefore, an ozone purification body that combines manganese dioxide and AC can be expected to allow to make up for the shortcomings of ozone purification function by manganese dioxide, and to afford ozone purification over a wider temperature region. Such an ozone purification body shows hence promise as an ozone purification body for installation in DOR systems.
However, findings by the inventors have revealed differences between the ozone purification characteristics of manganese dioxide and AC. It has been found that, as a result, the ozone purification function elicited through a simple combination of manganese dioxide and AC is inferior in some instances to that achieved when using manganese dioxide or AC singly, depending on the environment in which the vehicle is actually traveling (hereafter also referred to as “actual-road environment”).
SUMMARY OF THE INVENTIONThe invention provides an air purification device for vehicles such that the ozone purification function thereof can be brought out over long periods of time in a DOR system that utilizes an ozone purification body resulting from combining manganese dioxide and AC.
An air purification device for vehicles according to a first aspect of the invention has a vehicle component that is disposed at a site at which an air flow path is formed during travel of a vehicle; and an ozone purification body that is supported on the vehicle component and that includes manganese dioxide and AC as ozone purification components; wherein a weight ratio of AC in the ozone purification body ranges from 20% to 80%.
An air purification device for vehicles according to a second aspect of the invention has a vehicle component that is disposed at a site at which an air flow path is formed during travel of a vehicle; and an ozone purification body that is supported on the vehicle component and that includes manganese dioxide and AC as ozone purification components; wherein a weight ratio (manganese dioxide/AC) of the ozone purification components ranges from 0.25 to 4.0.
In the first or second aspect, the ozone purification body may be formed as a single-layer film on a surface of the vehicle component.
In the first or second aspect, the vehicle component may be at least one from among a radiator, an intercooler and an inverter for hybrid vehicles.
By virtue of these aspects, the invention succeeds in providing an air purification device for vehicles such that the ozone purification function of the device can be brought out over long periods of time in a DOR system that utilizes an ozone purification body resulting from combining manganese dioxide and AC.
Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:
[Configuration an Air Purification Device for Vehicles]
An embodiment of the invention will be explained below with reference to
A radiator 14 that cools cooling water that circulates in the internal combustion engine 12 is disposed in front of the internal combustion engine 12 of the vehicle 10. As denoted by the arrow in
The detailed configuration of the radiator 14 will be explained next with reference to
[Configuration of the Ozone Purification Body]
In the embodiment, the mixing ratio of AC and manganese dioxide (weight basis) that make up the ozone purification body is adjusted so as to range from 4:1 to 1:4. The weight ratio of AC in the ozone purification body is adjusted to range from 20% to 80%. The weight ratio (manganese dioxide/AC) in the ozone purification component ranges from 0.25 to 4.0. Ozone purification such that the environment in which the vehicle is actually traveling (hereafter also referred to as “actual-road environment”) is factored in is rendered possible by prescribing the blending ratio to lie within such a range. The grounds for the above mixing ratio are explained below.
The ozone purification function of AC will be explained first. AC has numerous pores formed therein, from the surface towards the interior. Ozone purification by AC takes place when ozone penetrates into the pores. Specifically, AC donates electrons to ozone. The activation energy of an ozone purification reaction is lowered as a result, and ozone is converted to oxygen and active oxygen (O3→O2+O*). The active oxygen that is generated in this ozone purification reaction has strong oxidizing power. Continued dwelling of active oxygen within the pores of the AC gives rise therefore to oxidation of the surrounding AC.
The solid line in
The ozone purification ratio of manganese dioxide for comparison is high at the initial stage, and over an extended period of time drops to about half that of the initial stage. That is, manganese dioxide exhibits better durability in the ozone purification function than AC. Such being the case, it is expected that the drop in ozone purification function of AC can be made up for by using manganese dioxide simultaneously with AC.
As
The tendency illustrated in
The inventors performed various endurance tests that assumed an actual-road environment. The results of these endurance tests will be explained with reference to
As
The rationale for the water resistance test is that air contains moisture. The water concentration in air ranges ordinarily from 0.8% to 2.4% (relative humidity of about 30% to about 80%). Accordingly, the results of
As
The chloride resistance test is performed to account for the influence of snow melting agents (NaCl and CaCl2). Snow melting agents, which are sprinkled on road surfaces for the purpose of freeze protection, fly off into air due to traction (splashing) and the like of a preceding vehicle, and become adhered to the radiator surface of a following vehicle. Accordingly, the results of
As
The purpose of the S-resistance test is to account for the influence of SOx and NOx in air. That is because these gases that are emitted by vehicles may for instance become adhered to the radiator of the traveling vehicle. Accordingly, the results of
In the embodiment, the mixing ratio of AC is adjusted to lie within the above ranges, on the basis of the various test results described above.
Recent years, in particular, have witnessed a trend towards suppression of water passage frequency in radiators for engines, as fuel economy in vehicles has become steadily better. There is also a trend towards easing the load of the internal combustion engine, and curtailing the water passage frequency to the engine radiator, in so-called hybrid vehicles that are equipped with an internal combustion engine and an electric motor, or with an internal combustion engine and a battery. Preferably, therefore, such a water passage environment is taken into account beforehand when an ozone purification body is to be supported on the radiator. Herein, the ratio of the components of the ozone purification body of the embodiment is adjusted on the basis of, for instance, the results of endurance tests in which the passing gas temperature is set to 25° C. Accordingly, a high ozone purification amount over the useful life can be achieved also in cases of continued running with low water passage frequency in the radiator.
[Configuration of the Ozone Purification Body Layer 20]
In the embodiment, the ozone purification body layer 20 is formed, on the fin 18, as a single-layer film of the ozone purification body. In addition to the above-described effects, degradation of the ozone purification function of AC can be suppressed satisfactorily by forming a single-layer film. The rationale for the single-layer film is explained next.
As
The above suggests that a synergistic effect of the use of manganese dioxide and AC can be expected to be elicited by forming the ozone purification body layer 20 as a single-layer film of an ozone purification body. In consequence, the embodiment allows achieving a high ozone purification amount over the useful life.
In the above embodiment, the ozone purification body is provided in the radiator 14, but the ozone purification body may be installed in an air-conditioning condenser, an intercooler, or an inverter for hybrid vehicles. Like the radiator 14, these components are installed in vehicles, and are cooled by a component (a refrigerant, in the case of water cooling) according to the same cooling principle of the radiator 14. The ozone purification body layer 20 can thus be likewise formed, in the same way as in the embodiment, on such components.
Claims
1. An air purification device for vehicles, comprising:
- a vehicle component that is disposed at a site at which an air flow path is formed during travel of a vehicle; and
- an ozone purification body that is supported on the vehicle component and that includes manganese dioxide and activated carbon, as ozone purification components,
- wherein a weight ratio of activated carbon in the ozone purification body ranges from 20% to 80%.
2. The air purification device for vehicles according to claim 1, wherein
- the ozone purification body is a single-layer film formed on a surface of the vehicle component.
3. The air purification device for vehicles according to claim 1, wherein
- the vehicle component is at least one from among a radiator, an intercooler and an inverter for hybrid vehicles.
4. An air purification device for vehicles, comprising:
- a vehicle component that is disposed at a site at which an air flow path is formed during travel of a vehicle; and
- an ozone purification body that is supported on the vehicle component and that includes manganese dioxide and activated carbon, as ozone purification components,
- wherein a weight ratio (manganese dioxide/activated carbon) of the ozone purification components ranges from 0.25 to 4.0.
5. The air purification device for vehicles according to claim 4, wherein
- the ozone purification body is a single-layer film formed on a surface of the vehicle component.
6. The air purification device for vehicles according to claim 4, wherein
- the vehicle component is at least one from among a radiator, an intercooler and an inverter for hybrid vehicles.
Type: Application
Filed: Jul 26, 2013
Publication Date: Jan 30, 2014
Applicant: TOYOTA JIDOSHA KABUSHIKI KAISHA (Toyota-shi)
Inventors: Kazuhiro SUGIMOTO (Susono-shi), Yoshihisa SHINODA (Susono-shi), Koichi HOSHI (Susono-shi), Takashi WATANABE (Gotemba-shi), Hiroaki KATSUMATA (Susono-shi)
Application Number: 13/951,618
International Classification: F01P 11/12 (20060101);