Patent Grant
10801403
The disclosure of Japanese Patent Application No. 2018-127729 filed on Jul. 4, 2018 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
The present disclosure relates to an internal combustion engine.
Internal combustion engines such as gasoline engines or diesel engines are typically constituted by an engine block, a cylinder head, and a piston. A combustion chamber of the internal combustion engine is defined by the bore surface of the cylinder block, the top surface of the piston assembled in the bore, the bottom face of the cylinder head and the top surfaces of intake and exhaust valves arranged in the cylinder head. As higher power is required for recent internal combustion engines, it is desired to reduce the cooling loss of the internal combustion engines. One example of a mean for reducing the cooling loss includes a method of forming a heat insulation coating on the inner wall of the combustion chamber.
The heat insulation coating that is formed on the wall surface of the combustion chamber is desirably formed from a material having not only heat resistance and heat insulation properties but a low thermal conductivity and a low thermal capacity. Specifically, for preventing steady elevation in wall temperature, it is desirable that the heat insulation coating should have a low thermal capacity so as to lower the wall temperature following a fresh air temperature in an intake stroke. Furthermore, in addition to the low thermal conductivity and the low thermal capacity, the coating is desirably capable of resisting explosion pressure at the time of combustion in the combustion chamber, injection pressure, and repeated stress of thermal expansion and thermal shrinkage, and has a high adhesion to a base material, such as a cylinder block.
An anodic oxide coating can be used as an example of such a heat insulation coating. The anodic oxide coating can be formed on a wall surface facing the combustion chamber of the internal combustion engine to thereby prepare an internal combustion engine having excellent heat insulation properties, low thermal conductivity, and a low thermal capacity. In addition to these capabilities, excellent swing characteristics are also an important capability required for the anodic oxide coating. In this context, the “swing characteristics” are characteristics by which the temperature of the anodic oxide coating follows a gas temperature in the combustion chamber although the anodic oxide coating possesses a heat insulation capability.
Examples of literatures disclosing the internal combustion engine having the anodic oxide coating formed on a wall surface facing the combustion chamber include Japanese Patent Application Publication Nos. 2013-60620 and 2015-31226 described below.
JP 2013-60620 A discloses an internal combustion engine prepared by forming an anodic oxide coating on a portion or the whole of a wall surface facing a combustion chamber, wherein the anodic oxide coating has, in the inside, voids and nanopores much smaller than the voids; and the internal combustion engine assumes a structure where at least one or some of the voids are sealed with a sealing material converted from a sealant, and at least one or some of the nanopores are not sealed. In JP 2013-60620 A, a sealing material is disposed on the surface of the anodic oxide coating.
JP 2015-31226 A discloses an internal combustion engine prepared by forming an anodic oxide coating on a portion or the whole of an aluminum-based wall surface facing a combustion chamber, wherein the anodic oxide coating has a film thickness in the range of 30 μm to 170 μm; the anodic oxide coating has first micropores having a microsized diameter and extending in the thickness direction or substantially in the thickness direction of the anodic oxide coating from the surface toward the inside of the anodic oxide coating, nanopores having a nanosized diameter and extending in the thickness direction or substantially in the thickness direction of the anodic oxide coating from the surface toward the inside of the anodic oxide coating, and second micropores having a microsized diameter and being present in the inside of the anodic oxide coating; and the internal combustion engine assumes a structure where at least one or some of the first micropores and the nanopores are sealed with a sealing material converted from a sealant, and at least one or some of the second micropores are not sealed. In JP 2015-31226 A, as in JP 2013-60620 A, a sealing material is disposed on the surface of the anodic oxide coating.
In JP 2013-60620 A and JP 2015-31226 A, coating strength is improved by disposing a sealing material on an anodic oxide coating. However, use of a sealant seals pores present in the anodic oxide coating and therefore reduces a porosity, which is important for obtaining favorable swing characteristics. Furthermore, the presence of the sealant increases a thermal capacity and may not produce favorable swing characteristics. Moreover, a cost is increased because an operation of disposing the sealant, a material, etc. are necessary.
On the other hand, the mere absence of the sealant causes combustion gas to invade nanopores. Upon entry of combustion gas into the nanopores, a heat insulation effect is decreased in the portion where the gas has entered, leading to reduction in the heat insulation effect of the film as a whole. As a result, for conferring sufficient heat insulation properties, it becomes necessary to increase the thickness of the anodic oxide coating. However, the increased thickness of the anodic oxide coating in turn leads to reduction in swing characteristics.
The present disclosure provides an internal combustion engine having a formed anodic oxide coating having favorable heat insulation properties and swing characteristics.
(1) An aspect of the present disclosure relates to an internal combustion engine having an anodic oxide coating formed on at least a portion of an aluminum-based wall surface facing a combustion chamber. The anodic oxide coating has a plurality of nanopores extending substantially in a thickness direction of the anodic oxide coating, a first micropore extending from the surface toward the inside of the anodic oxide coating, and a second micropore present in the inside of the anodic oxide coating. The surface opening diameter of the nanopores on the surface of the anodic oxide coating is 0 nm or larger and smaller than 30 nm. The inside diameter of the nanopores in the inside of the anodic oxide coating is larger than the surface opening diameter. A film thickness of the anodic oxide coating is 15 μm or larger and 130 μm or smaller. The porosity of the anodic oxide coating is 23% or more.
(2) The difference between the surface opening diameter and the inside diameter of the nanopores may be 7 nm or larger.
(3) The nanopores may not open to the surface of the anodic oxide coating.
(4) The difference between the surface opening diameter and the inside diameter of the nanopores may be 20 nm or larger.
(5) An aluminum-based material constituting the aluminum-based wall surface may contain at least one metal selected from Si and Cu, and the content of the metal in the aluminum-based material may be 5% by mass or more.
(6) No sealing material may be disposed on the anodic oxide coating.
(7) The anodic oxide coating may be exposed to the combustion chamber.
(8) The internal combustion engine may have a piston, and the anodic oxide coating may be formed at least on a piston top surface.
(9) The anodic oxide coating formed on the piston top surface may include a thin-film portion having the film thickness of 15 μm or larger and 60 μm or smaller.
(10) The thin-film portion may be disposed in a portion substantially contributing to the formation of a tumble flow in the piston top surface.
(11) The film thickness of the anodic oxide coating formed on the piston top surface except for the thin-film portion may be larger than 60 μm and 100 μm or smaller.
(12) The piston top surface may include a cavity portion, and the thin-film portion may be disposed in the cavity portion.
(13) The piston top surface may further include valve recess portions, and the thin-film portion may also be disposed in the valve recess portions in addition to the cavity portion.
(14) The piston top surface may further include a squish portion, and the film thickness of the anodic oxide coating in the squish portion may be larger than 60 μm and 100 μm or smaller.
(15) The thin-film portion may be disposed in a central region including the center of the piston top surface, and the film thickness of the anodic oxide coating disposed in an outer region positioned on the outer side of the central region may be larger than 60 μm and 100 μm or smaller.
(16) The ratio between the area Sc of the central region and the area So of the outer region (Sc:So) may be 1:5 to 5:1.
The present disclosure can provide an internal combustion engine having a formed anodic oxide coating having favorable heat insulation properties and swing characteristics.
Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein
The present embodiment relates to an internal combustion engine having an anodic oxide coating formed on at least a portion of an aluminum-based wall surface facing a combustion chamber, wherein the anodic oxide coating has a plurality of nanopores extending substantially in the thickness direction of the anodic oxide coating, a first micropore extending from the surface toward the inside of the anodic oxide coating, and a second micropore present in the inside of the anodic oxide coating; the surface opening diameter of the nanopores on the surface of the anodic oxide coating is 0 nm or larger and smaller than 30 nm; the inside diameter of the nanopores in the inside of the anodic oxide coating is larger than the surface opening diameter; the film thickness of the anodic oxide coating is 15 μm or larger and 130 μm or smaller; and the porosity of the anodic oxide coating is 23% or more.
The present embodiment can provide an internal combustion engine having a formed anodic oxide coating having favorable heat insulation properties and swing characteristics. More specifically, in the present embodiment, the nanopores have a narrow surface opening diameter. Hence, the invasion of combustion gas into the nanopores is reduced, so that the anodic oxide coating is capable of having high heat insulation properties. Furthermore, the film thickness of the anodic oxide coating is as small as 15 μm or larger and 130 μm or smaller while the porosity falls within the predetermined range. The resulting anodic oxide coating achieves a lower thermal capacity and can also have excellent swing characteristics.
Hereinafter, the configuration of the internal combustion engine of the present embodiment will be described with reference to the drawings.
In the present embodiment, the internal combustion engine may be intended for any of gasoline engines and diesel engines. As for the configuration of the internal combustion engine, the internal combustion engine is typically constituted by an engine block, a cylinder head, and a piston as already mentioned. A combustion chamber of the internal combustion engine is defined by, for example, the bore surface of the cylinder block, the top surface of the piston assembled in the bore, the bottom face of the cylinder head and the top surfaces of intake and exhaust valves arranged in the cylinder head.
In the present embodiment, each member constituting the internal combustion engine is made of an aluminum-based material. The aluminum-based wall surface is the wall surface of a wall member made of an aluminum-based material. Examples of the aluminum-based material include aluminum and alloys thereof, and aluminum-plated iron-based materials. The aluminum-based material includes, for example, a high-strength aluminum alloy. An anodic oxide coating formed by anodization on a wall surface with aluminum or an alloy thereof as a base material is alumite.
In the present specification, the “nanopore” means a nanosized pore extending substantially in the thickness direction of the anodic oxide coating. The nanosize means that the diameter of a circle (also referred to as a circle-equivalent diameter) having the same area as the maximum sectional area (sectional area at a horizontal section where the area is largest) of the nanopores is of the order of nm (1 nm or larger and smaller than 1 μm). The nanopores are not necessarily required to open to the surface of the anodic oxide coating and may not open to the coating surface. The horizontal direction means the planar direction of the aluminum-based wall surface.
In the present specification, the “first micropore” means a pore (e.g., a crack) extending from the surface toward the inside of the anodic oxide coating. The first micropore opens to the surface of the anodic oxide coating, and the diameter of a circle (circle-equivalent diameter) having the same area as the opening area of the first micropore is of the order of μm (1 μm or larger). The first micropore usually extends substantially in the thickness direction of the anodic oxide coating from the surface toward the inside of the anodic oxide coating.
In the present specification, the “second micropore” means a pore (e.g., an inner defect) present in the inside of the anodic oxide coating. The second micropore does not face the surface of the anodic oxide coating, i.e., does not open to the surface of the anodic oxide coating. The diameter of a circle having the same area as the maximum sectional area (sectional area at a horizontal section where the area is largest) of the second micropore is of the order of μm (1 μm or larger). The circle-equivalent diameter of the second micropore is, for example, in the range of 1 to 100 μm.
The nanopores and the first micropore extend substantially in the thickness direction of the anodic oxide coating. The phrase “substantially in the thickness direction” is meant to include a form extending in a direction sloped from the thickness direction, a form extending while meandering zigzag from the thickness direction, etc. The form of the second micropore includes a form extending in a direction orthogonal to the thickness direction of the anodic oxide coating, a form extending in a direction sloped from the direction orthogonal to the thickness direction of the anodic oxide coating, a form extending while meandering zigzag in the direction orthogonal to the thickness direction of the anodic oxide coating, etc. in the inside of the anodic oxide coating.
The opening diameters of the nanopores and the micropores can be measured by extracting each micropore or nanopore from a given area in SEM image photograph data or TEM image photograph data on the cross-section of the anodic oxide coating, measuring the diameters (circle-equivalent diameters) of the extracted pores, and determining an average value.
In the present embodiment, the anodic oxide coating may be formed on the whole of the wall surface facing the combustion chamber or may be formed only on a portion of the wall surface. Examples of the latter embodiment can include a mode in which the coating is formed only on the piston top surface or only on the valve top surfaces.
In the present embodiment, the anodic oxide coating can be formed by anodizing the aluminum-based wall surface facing the combustion chamber of the internal combustion engine.
In the present embodiment, the opening diameter of the nanopores on the surface of the anodic oxide coating is 0 nm or larger and smaller than 30 nm. When the surface opening diameter of the nanopores is smaller than 30 nm, the invasion of gas into the nanopores can be effectively reduced. The reduction in the invasion of combustion gas can curb decrease in heat insulation effect. If the invasion of combustion gas into the inside of the coating cannot be reduced, a heat insulation effect is decreased in the portion invaded by the gas. Therefore, the heat insulation effect of the film as a whole is also decreased. The surface opening diameter of the nanopores is preferably 20 nm or smaller, more preferably 15 nm or smaller, further preferably 10 nm or smaller, particularly preferably 5 nm or smaller, from the viewpoint of effectively reducing the invasion of gas. The surface opening diameter of the nanopores is more preferably 0 nm. Specifically, it is more preferred that the nanopores should not open to the surface of the anodic oxide coating. When the nanopores have no opening to the surface of the anodic oxide coating, the invasion of gas into the nanopores is markedly reduced.
In the present embodiment, the pore size of the nanopores in the inside of the anodic oxide coating (also referred to as an inside diameter) is larger than the surface opening diameter mentioned above. Specifically, the nanopores are formed at the time of anodization of the aluminum-based wall surface. The diameter of the nanopores is small at the opening of the coating surface and is gradually increased from the surface to a certain depth (e.g., approximately 10 μm from the opening), and the subsequent nanopores extend from the surface toward the inside while keeping an almost constant sectional area (horizontal sectional area). The “inside opening diameter of the nanopores” or the “opening diameter of the nanopores in the inside” refers to the opening diameter of the pore portion extending while keeping an almost constant sectional area. The inside diameter of the nanopores is, for example, 25 nm or larger, 30 nm or larger, 35 nm or larger, 40 nm or larger, or 50 nm or larger.
The surface opening diameter of the nanopores can be obtained by determining the circle-equivalent diameter (average value) of the nanopores from a SEM image of the surface of the anodic oxide coating. The circle-equivalent diameter of the nanopores can be determined from the SEM image using commercially available software. Examples of the software can include WinROOF (manufactured by Mitani Corp.).
The inside diameter of the nanopores can be obtained by shaving the anodic oxide coating from the surface to the predetermined depth using a cross-section polisher or the like, photographing the exposed surface under SEM, and determining the circle-equivalent diameter of the nanopores from the obtained image. The circle-equivalent diameter can be determined from the SEM image using commercially available software, as in the surface opening diameter. The “inside diameter of the nanopores” can be measured, for example, in the middle of the thickness direction of the anodic oxide coating.
In the present embodiment, the difference between the surface opening diameter and the inside diameter of the nanopores is preferably 7 nm or larger, more preferably 10 nm or larger, still more preferably 15 nm or larger, further preferably 20 nm or larger. A larger difference between the surface opening diameter and the inside diameter of the nanopores can increase a porosity. In a specific embodiment, the nanopores do not open to the coating surface and preferably have an inside diameter of 20 nm or larger, more preferably 25 nm or larger, further preferably 30 nm or larger.
In the present embodiment, the film thickness (indicated by t in
The film thickness can be obtained by measuring film thicknesses at 5 sites at the cross-section of the anodic oxide coating, and determining an average value.
The porosity can be measured by the following method: the volume of the coating is determined from the area and the film thickness of the anodic oxide coating. Also, the weight of the coating is determined from the difference in weight before and after removal of the coating. The bulk density of the coating is calculated. The porosity is calculated according to the following expression using the obtained bulk density of the coating and an alumina density (3.9 g/cm3): Porosity=1−(Bulk density of the coating/Alumina density)
In the present embodiment, the aluminum-based material constituting the aluminum-based wall surface preferably contains 5% by mass or more of at least one metal selected from Si and Cu. When the content of at least one metal selected from Si and Cu in the aluminum-based material is 5% by mass or more, the formation of the micropores (particularly, the second micropore) can be promoted to thereby effectively improve a porosity. The content of Si in the aluminum-based material is preferably 5% by mass or more and 20% by mass or less. The content of Cu in the aluminum-based material is preferably 0.3% by mass or more and 7% by mass or less. The content of Al in the aluminum-based material is, for example, 70% by mass or more or 75% by mass or more. Also, the content of Al in the aluminum-based material is, for example, 95% by mass or less or 90% by mass or less. Examples of a metal, other than Al, Si and Cu, contained in the aluminum-based material include Mg, Zn, Ni, Fe, Mn, and Ti.
The swing characteristics of the anodic oxide coating can be evaluated by a cooling test (quenching test). In the cooling test, a test piece provided on one surface with the anodic oxide coating is used. While the back surface (surface provided with no anodic oxide coating) is continuously heated with the predetermined high-temperature jet, cooling air of the predetermined temperature is injected from the front surface (surface provided with the anodic oxide coating) of the test piece to lower the front-surface temperature of the test piece. The front surface temperature is measured. Then, a cooling curve is prepared from the coating surface temperature and the time. Further, the rate of temperature fall is evaluated from the cooling curve. This rate of temperature fall is evaluated, for example, by reading the time required for the coating surface temperature to fall by 40° C. (40° C.-fall time) from a graph.
Specifically, the quenching test is carried out on a plurality of test pieces, and a 40° C.-fall time is measured for each of the test pieces. An approximated curve is prepared as to a plurality of plots defined by the rate of improvement in fuel efficiency and the 40° C.-fall time. Then, the value of the 40° C.-fall time corresponding to 5% as the rate of improvement in fuel efficiency described above is read. When this value is 45 msec or shorter, the coating is found to have an excellent fuel efficiency-improving effect. A coating having a shorter 40° C.-fall time has a lower thermal conductivity and thermal capacity and a higher fuel efficiency-improving effect.
In the present embodiment, no sealing material is preferably disposed on the anodic oxide coating. In the present embodiment, the anodic oxide coating is preferably exposed to the combustion chamber. If a sealing material is disposed on the anodic oxide coating, the nanopores and/or the first micropore are sealed with the sealing material, leading to reduction in porosity. Furthermore, the presence of the sealing material increases a thermal capacity. Hence, it is preferred that no sealing material should be disposed on the anodic oxide coating.
The anodic oxide coating of the present embodiment is prepared by dipping the aluminum-based material in an acidic electrolytic solution (e.g., an aqueous sulfuric acid solution), and electrifying the material. Specifically, in a film formation apparatus, voltage is applied to between electrodes with the electrolytic solution injected to perform electrolysis. As a result, the wall surface (e.g., the piston top surface) of the aluminum-based material is oxidized as an anode, so that the anodic oxide coating is formed. In order to form the anodic oxide coating according to the present embodiment, anodization conditions can be appropriately adjusted. For example, the porosity of the anodic oxide coating can be adjusted depending on the applied voltage. Also, the thickness of the anodic oxide coating can be adjusted depending on the application time. It is preferred to remove the heat of oxidation reaction using a cooling apparatus during film formation treatment. For removing the heat of oxidation reaction from the wall surface of the material, it is preferred to perform anodization while the electrolytic solution is allowed to flow in contact with the film formation surface. Specifically, the anodic oxide coating can be formed with an apparatus having a configuration as shown in
The temperature of the electrolytic solution is, for example, 0° C. or higher and 10° C. or lower, preferably 0° C. or higher and 4° C. or lower.
The current density is, for example, 0.1 A/cm2 or larger and 1.0 mA/cm2 or smaller.
The energization time (film formation time) is, for example, 5 seconds or longer and 180 seconds or shorter.
In the present embodiment, the anodic oxide coating is preferably formed at least on the piston top surface. Specifically, the anodic oxide coating is preferably formed on the whole piston top surface of the internal combustion engine. In the present embodiment, the anodic oxide coating formed on the piston top surface preferably includes a thin-film portion having a film thickness of 15 μm or larger and 60 μm or smaller.
In the present embodiment, the thin-film portion is preferably disposed in a portion substantially contributing to the formation of a tumble flow in the piston top surface. The portion substantially contributing to the formation of a tumble flow is a portion with which the tumble flow comes into active contact. In the present embodiment, the film thickness of the anodic oxide coating except for the thin-film portion is preferably larger than 60 μm and 100 μm or smaller. Hereinafter, the anodic oxide coating portion having a film thickness of larger than 60 μm and 100 μm or smaller is referred to as a thick-film portion.
Hereinafter, the aforementioned embodiment will be specifically described.
In order to circumvent the interference between the intake valve 142 and the exhaust valve 152, intake valve recess portions 180a and exhaust valve recess portions 180b are also formed on the piston top surface. In
In
In the present embodiment, as shown in
In
The thin-film portion and the thick-film portion can be established in the piston top surface through the use of, for example, masking. In general, the anodic oxide coating has a large film thickness on a casting surface and has a small film thickness on a polished surface. The thin-film portion and the thick-film portion can be established through the use of this fact. The thin-film portion and the thick-film portion can be established, for example, through one coating treatment step by anodizing a piston top surface having a cavity portion and valve recess portions formed from a polished surface, and a squish portion formed from a casting surface.
Hereinafter, the present embodiment will be described with reference to Examples. However, the present embodiment is not limited by Examples given below.
Aluminum-based base materials (base materials A and B) having the composition of components shown in Table 1 below were provided.
In Examples, an anodic oxide coating was formed on each of the aluminum-based base materials A and B using an apparatus having the configuration as shown in
A test piece E2 was prepared in the same way as in Example 1 except that the flow rate of the electrolytic solution from the discharge portion was set to 25 L/min.
A test piece E3 was prepared in the same way as in Example 1 except that the flow rate of the electrolytic solution from the discharge portion was set to 30 L/min.
A test piece C1 was prepared in the same way as in Example 1 except that the base material B was used instead of the base material A.
A test piece C2 was prepared in the same way as in Comparative Example 1 except that the flow rate of the electrolytic solution from the discharge portion was set to 25 L/min.
A test piece C3 was prepared in the same way as in Example 1 except that the flow rate of the electrolytic solution from the discharge portion was set to 5 L/min.
A test piece C4 was prepared in the same way as in Example 1 except that the flow rate of the electrolytic solution from the discharge portion was set to 15 L/min.
As a result of measuring the film thickness of the anodic oxide coating as to the obtained test pieces E1 to E3 and C1 to C4, all the film thicknesses were 15 nm. The film thickness of the anodic oxide coating was measured by observing the cross-section of the coating under SEM, measuring film thicknesses at 5 sites, and determining an average value.
The porosity was measured as to the obtained test pieces E1 to E3 and C1 to C4 by the following method: the volume of the coating was determined from the area and the film thickness of the anodic oxide coating. Also, the weight of the coating was determined from the difference in weight before and after removal of the coating. The bulk density of the coating was calculated. The porosity was calculated according to the following expression using the obtained bulk density of the coating and an alumina density (3.9 g/cm3):
Porosity=1−(Bulk density of the coating/Alumina density)
The results are shown in Table 2.
The surface opening diameter of the nanopores was measured as to the obtained test pieces E1 to E3 and C1 to C4 by the following method: the surface of the anodic oxide coating was photographed under SEM to obtain a SEM image. The circle-equivalent diameter of the nanopores was determined from the obtained SEM image using image analysis software WinROOF (manufactured by Mitani Corp.).
The inside diameter of the nanopores was measured as to the obtained test pieces E1 to E3 and C1 to C4 by the following method: the anodic oxide coating was shaved using a cross-section polisher or the like, and the exposed surface was photographed under SEM to obtain a SEM image. The circle-equivalent diameter of the nanopores was determined from the obtained image using image analysis software WinROOF (manufactured by Mitani Corp.).
The swing characteristics of the anodic oxide coating were evaluated as to the obtained test pieces E1 to E3 and C1 to C4 by the following method.
As shown in
One example of a targeted value achieved by the capabilities of the anodic oxide coating includes 5% improvement in fuel efficiency. This 5% improvement in fuel efficiency is a value that can clearly demonstrate the rate of improvement in fuel efficiency without being buried as a measurement error in an experiment, and can achieve reduction in NOx by shortening the warm-up time of a NOx reduction catalyst through the elevation of an exhaust gas temperature. In this context,
The results of measuring the porosity and evaluating the swing characteristics are shown in Table 2 below.
As is evident from Table 2, a 40° C.-fall time of 45 msec was obtained in Examples 1 to 3, and the test pieces E1 to E3 exhibited excellent swing characteristics.
The embodiments of the present disclosure are described above with reference to the drawings. However, the specific configuration is not limited by the embodiments given herein. Even various changes, modifications, and the like made in design, etc. without departing from the present disclosure are included in the scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-127729 | Jul 2018 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20140245994 | Nishikawa | Sep 2014 | A1 |
| 20160186654 | Takagishi | Jun 2016 | A1 |
| 20170254294 | Murakami | Sep 2017 | A1 |
| Number | Date | Country |
|---|---|---|
| 102017104090 | Sep 2017 | DE |
| 2013-060620 | Apr 2013 | JP |
| 2014227855 | Dec 2014 | JP |
| 2015-031226 | Feb 2015 | JP |
| 2016-216763 | Dec 2016 | JP |
| 2017122271 | Jul 2017 | JP |
| 2017155639 | Sep 2017 | JP |
| 2012025812 | Mar 2012 | WO |
| 2013038249 | Mar 2013 | WO |
| 2015019145 | Feb 2015 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20200011237 A1 | Jan 2020 | US |
