JP6035795B2 - Heat shield film manufacturing method, heat shield film, and internal combustion engine - Google Patents

Description

  The present invention relates to a method for manufacturing a thermal barrier film that reduces heat transfer, a thermal barrier film, and an internal combustion engine.

  In order to improve fuel efficiency, it is effective to improve the thermal efficiency of the internal combustion engine. In order to improve the thermal efficiency of the internal combustion engine, a structure that does not release the heat generated during combustion is required. That is, the inner wall of the combustion chamber is formed with a structure having a low thermal conductivity, that is, a heat insulating property or a high heat shielding property.

  Therefore, there is a so-called ceramic engine using a ceramic having low thermal conductivity. For example, an engine in which the top surface portion of a piston is made of ceramic and attached with a gap between the piston body and air, an engine coated with ceramics, or an engine in which the combustion chamber itself is made of ceramics.

  However, since the heat capacity of the ceramic portion is large and the temperature is high even during the intake stroke, there is a problem that the fuel efficiency deteriorates instead of increasing the charging efficiency. In addition, since the ceramic itself is expensive and difficult to process, there is a problem that the cost is high.

  In view of this, there is an apparatus for improving the thermal efficiency by reducing the heat transfer from the combustion gas in the combustion chamber by forming a heat shield layer on the inner wall of the combustion chamber of the internal combustion engine (see, for example, Patent Document 1 or 2). . These devices increase the porosity in the thermal barrier layer and improve the thermal insulation or thermal insulation of the thermal barrier layer by utilizing the relatively low thermal conductivity of air. .

  In the apparatus described in Patent Document 1, a heat shield film is formed of an anodic oxide film, and at the time of formation, pores called porous are generated in the film depending on conditions such as the type of electrolyte and metal, temperature, voltage, etc. The rate is increasing. In the device described in Patent Document 2, spherical mesoporous silica particles are mixed into the heat insulating material to increase the porosity.

  However, these methods have a problem that they cannot be mass-produced at low cost because construction using special materials or complicated construction is necessary and construction takes time. Further, the apparatus described in Patent Document 1 has a problem that the object to be coated needs to be conductive because the thermal barrier layer is formed of an anodized film. On the other hand, the device described in Patent Document 2 has a problem in terms of strength because it is attached with an adhesive or the like when the heat shield layer is used for the piston.

JP 2010-249008 A JP 2011-052630 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a thermal barrier film having a high hardness and a low heat transfer property in a short time and an easy method even when the film thickness is reduced. It is providing the manufacturing method of the thermal insulation film | membrane which can be manufactured by, a thermal insulation film | membrane, and an internal combustion engine.

In order to solve the above-mentioned object, a method for manufacturing a heat shield film according to the present invention is a method for manufacturing a heat shield film including a metal plating layer that covers a surface of an object to be plated in a state of being laminated on the surface of an object to be plated. inside dispersed microbubbles, said object to be plated is plated by the plating solution, the metal plating layer mainly composed of nickel on the surface of the object to be message key was prepared by encapsulating the microbubbles It is a method characterized by precipitation.

  The microbubble here is a fine bubble having a diameter of 50 μm or less, and its rising speed in the liquid is slower than that of a normal bubble, stays in the liquid for a long period of time, and is negatively charged. Bubbles repel each other and the bubble concentration does not decrease.

  According to this method, since the microbubbles are included, the porosity in the heat shielding film increases, so that the heat shielding property can be improved even if the film thickness is reduced. In addition, the microbubbles are dispersed substantially uniformly in the plating solution due to their properties, and can be easily uniformized.

Moreover, even if the film thickness is reduced, a thermal barrier film having high hardness and low thermal conductivity can be produced in a short time by encapsulating microbubbles in the metal plating layer . And it can manufacture only by disperse | distributing microbubble to a plating liquid, and since a thermal-insulation layer can be formed in a to-be-plated object in a short time cheaply, it can mass-produce.

In the method for manufacturing a thermal barrier film, air introduced from the outside or vapor generated by reducing the pressure of the plating solution is microbubbled, and the diameter of the plating solution is larger than 1 μm. When the microbubbles of 10 μm or less are dispersed, the microbubbles can be easily dispersed in the plating solution.

  This microbubble is converted into microbubbles by using the gas-liquid shearing method, the pressure-reducing method, or the ultrasonic method, etc., when the air introduced into the microbubble generator or the plating solution vapor generated when the plating solution is decompressed is used. It is a thing. Since the microbubbles having a diameter of 50 μm or less are uniformly dispersed in the plating solution, it is possible to easily improve the porosity of the plating film and to disperse the holes substantially uniformly.

In addition, in the method for manufacturing a thermal barrier film, the plating solution of hypophosphorous acid aqueous solution is impregnated with a reducing agent, heated, and encapsulated with the microbubbles by electrons released by oxidation of the reducing agent. When the metal plating layer is deposited on the object to be plated, a heat-shielding film can be produced by so-called electroless nickel plating, and unlike electroplating, it does not require energization. A thermal barrier film can be formed.

Further, Saeginetsumaku to solve the above problem, in Saeginetsumaku having a metal plating layer covering the surface with a laminated state on the surface of the object to be plated, the metal plating layer containing the microbubbles It is characterized by that. According to this configuration, since the microbubbles dispersed substantially uniformly in the metal plating layer can improve the porosity inside the coating, the thermal conductivity can be lowered. Moreover, since it is a metal plating layer , the hardness of a thermal barrier film can be made high.

In addition, in the above heat-shielding film, when the metal plating layer having a thickness of 100 μm or less contains the microbubbles having a diameter larger than 1 μm and 10 μm or less, the heat capacity of the heat-shielding film is reduced. At the same time, the heat shielding property can be improved. In addition, since the microbubbles can be dispersed in the plating solution and the metal plating layer can be deposited on the object to be plated, it is possible to easily manufacture a heat-shielding film having a thin film thickness and a high heat-shielding property in a short time. be able to.

The diameter of the microbubbles is 50 μm or less where the characteristics of the microbubbles are expressed and is larger than 1 μm, preferably 30 μm or less so that the number of bubbles is several hundred / mL. A so-called high-concentration type microbubble having a thickness of 10 μm or less, which is several thousand / mL, is preferable.

  In addition, an internal combustion engine for solving the above-described problem is configured to include the above-described heat shield film on at least a part of the piston top surface portion including the inner wall of the combustion chamber. According to this configuration, it is possible to prevent the heat generated in the combustion chamber from being transmitted to the piston body, so that the cooling loss can be reduced. Thereby, fuel consumption can be improved.

On the other hand, an internal combustion engine for solving the above problem is characterized in that the thermal barrier film is provided on at least one of the lower surface of the cylinder head, the lower surface of the exhaust valve, the lower surface of the intake valve, and the inner surface of the cylinder bore around the combustion chamber. It is configured with. According to this configuration, it is possible to prevent the heat generated in the combustion chamber from being transmitted to the outside, as described above. In addition, since the heat shielding film is a metal plating layer , the surface is fine and the hardness is high, so that the heat shielding film can be applied to sliding surfaces such as the inner surface of the cylinder bore.

  Furthermore, an internal combustion engine for solving the above problem is configured to include the heat shield film on at least one of an exhaust manifold, an exhaust pipe, an inlet manifold, and an intake pipe. According to this configuration, the intake air can be prevented from being heated, and the exhaust gas can be prevented from being cooled.

  According to the present invention, even if the film thickness is reduced, a thermal barrier film having high hardness and low heat transfer can be manufactured in a short time and with an easy method. In addition, by incorporating microbubbles, uniform pores can be easily dispersed in the thermal barrier film and the film thickness can be reduced.

It is sectional drawing which showed the thermal barrier film of embodiment which concerns on this invention. It is the block diagram which showed the apparatus which manufactures the thermal barrier film of 1st Embodiment which concerns on this invention. It is the block diagram which showed the apparatus which manufactures the thermal barrier film of 2nd Embodiment which concerns on this invention. 1 is a cross-sectional view showing an internal combustion engine according to an embodiment of the present invention.

  Hereinafter, a method for manufacturing a heat shield film, a heat shield film, and an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings. Note that the dimensions of the drawings are changed so that the configuration can be easily understood, and the ratios of the thicknesses, widths, lengths, and the like of the respective members and parts do not necessarily match the ratios of actually manufactured parts. In particular, the film thickness is very thin, 50 μm to 100 μm, but is shown thick in the drawing.

First, a thermal barrier film according to an embodiment of the present invention will be described with reference to FIG. The thermal barrier film 10 is formed of a metal plating layer 12 containing the microbubbles 11, deposits on the object to be plated 1, and shields heat from the combustion part 2.

  The heat shield film 10 is a very thin film, and the film thickness h is preferably 600 μm or less, more preferably 50 μm to 100 μm. When the film thickness h is reduced, for example, when the film is formed on the inner wall of the combustion chamber, the heat capacity can be reduced. By forming the thermal barrier film 10 to such a thickness that the thermal barrier effect does not decrease and the thermal capacity does not increase, a decrease in volumetric efficiency due to an increase in the thermal capacity is prevented, and heat energy is accumulated to generate in the combustion chamber It is possible to solve the problem that the temperature rises and air does not enter in the next stroke.

The microbubble 11 is a fine bubble, and its diameter r is 50 μm or less, 1 μm.
It is a larger bubble (a bubble having a diameter r of 1 μm or less is called a nanobubble). When the bubble diameter r is 50 μm or less, the following properties are obtained.

  Since the microbubbles 11 have a fine bubble volume, the speed of rising in the liquid is slow, and the microbubbles 11 have a property of staying in the liquid for a long time compared to normal bubbles. For example, a bubble having a diameter r of 10 μm only rises by about 3 mm per minute.

  Moreover, the microbubble 11 has a side surface as a colloid and is negatively charged. For this reason, the microbubbles 11 repel each other in the liquid. Because of this property, there is no coupling between the microbubbles 11 and the bubble concentration does not decrease. In addition, due to this property, the microbubbles 11 also have a property of diffusing uniformly in the liquid.

The thermal barrier film 10 includes microbubbles 11 of 50 μm or less, preferably so-called low-concentration microbubbles 11 of 30 μm or less, more preferably so-called high-concentration microbubbles 11 of 10 μm or less in the metal plating layer 12. Contain. The smaller microbubbles 11 are preferable because the rising speed in the liquid is slow.

The Saeginetsumaku 10, since the metal plating layer 12 containing the microbubbles 11, to increase the porosity of the metal plating key layer 12, it is possible to reduce the thermal conductivity from the combustion section 2. Thereby, even if it forms the film thickness h thin, heat-conductivity can be reduced and heat insulation can be carried out by including the microbubble 11. In addition, since the microbubbles 11 are uniformly diffused in the liquid due to their properties, the microbubbles 11 can be easily dispersed uniformly in the thermal barrier film 10.

Next, the manufacturing method of the thermal barrier film according to the embodiment of the present invention will be described with reference to FIGS. The method for manufacturing the thermal barrier film 10 is a method in which the object to be plated 1 is immersed in a plating solution 12a in which microbubbles 11 are generated, and the metal plating layer 12 is deposited on the object 1 to be plated.

  First, as shown in FIG. 2, a manufacturing apparatus 20 used in the method for manufacturing a thermal barrier film according to the first embodiment of the present invention includes a plating deposition apparatus 21 and a microbubble generator 22. Are provided with a heating plating bath 23, a heating device 24, and a stirring device 25, and a microbubble generator 22 with a plating solution suction pipe 26, an air suction tube 27, and a plating solution discharge pipe 28, respectively.

Next, a method for depositing the thermal barrier film 10 on the object to be plated 1 by electroless nickel plating using the manufacturing apparatus 20 will be described. In this embodiment, a hypophosphorous acid aqueous solution is used for the plating solution 12a, and a reducing agent 13 such as an iron group element such as iron, nickel, cobalt, palladium, or a metal of a platinum group element is added to the hypophosphorous acid aqueous solution. Electroless nickel plating that impregnates and heats to deposit a nickel film as the metal plating layer 12 is used. Therefore, hereinafter, the plating solution 12 a is a hypophosphorous acid aqueous solution 12 a and the metal plating layer 12 is a nickel film 12.

  First, the hypophosphorous acid aqueous solution 12 a injected into the heating plating tank 23 is sucked into the microbubble generator 22 from the plating solution suction pipe 26. Next, the air introduced from the air suction pipe 27 into the hypophosphorous acid aqueous solution 12a in the microbubble generator 22 is converted into microbubbles by a gas-liquid shearing method of a well-known technique, and the microbubbles 11 are placed in the hypophosphorous acid aqueous solution 12a. To distribute. Next, the hypophosphorous acid aqueous solution 12 a containing the microbubbles 11 is returned from the plating solution discharge pipe 28 to the heating plating tank 23.

When the microbubbles 11 are sufficiently dispersed in the hypophosphorous acid aqueous solution 12 a in the heating plating bath 23, the reducing agent 13 is then impregnated and the hypophosphorous acid aqueous solution 12 a is heated by the heating device 24. Next, when the object to be plated 1 is immersed in the hypophosphorous acid aqueous solution 12a of the heating plating tank 23, the nickel film 12 in which the microbubbles 11 are included in the object 1 to be plated is generated by the electrons released by the oxidation of the reducing agent 13. Precipitation is complete.

  If the surface of the nickel film 12 has irregularities by including the microbubbles 11, the microbubbles 11 may be immersed in a hypophosphorous acid aqueous solution 12a that does not disperse, and only the surface may be plated. Thereby, the unevenness | corrugation of the surface can be filled and the surface can be made smooth.

The above method of production, in the liquid of the electrolytic plating or electroless plating, when a plating while suspended particulates, these particulates to form a composite metal plating layer which is contained in the metal plating layer, the so-called nanoparticle composite This is an application of plating, in which microbubbles 11 are used instead of fine particles.

  According to the above method, the thin thermal barrier film 10 including the microbabs 11 can be deposited on the workpiece 1 by electroless nickel plating in a short time. Thereby, it can be easily applied to mass-produced products such as automobile engines.

  In addition, since the microbubbles 11 are dispersed substantially uniformly in the hypophosphorous acid aqueous solution 12a due to the nature thereof, the vacancies inside the thermal barrier film 10 can be easily dispersed substantially uniformly. In addition, since it can be produced by electroless plating, the thermal barrier film 10 can be deposited on non-conductive materials such as plastic and ceramic.

  Next, a method for manufacturing a thermal barrier film according to a second embodiment of the present invention will be described with reference to FIG. The manufacturing apparatus 30 includes a microbubble generator 31 that does not include an air suction pipe and does not suck air, instead of the microbubble generator 22 of the manufacturing apparatus 20 according to the first embodiment.

  In the manufacturing method of the second embodiment, the hypophosphorous acid aqueous solution 12 a is sucked from the heating plating tank 23 into the microbubble generator 31 through the plating solution suction pipe 32. Next, the hypophosphorous acid aqueous solution 12a is depressurized inside the microbubble generator 31, and the vapor (not shown) of the hypophosphorous acid aqueous solution 12a generated therewith is known to be a gas-liquid shearing method, a pressurized depressurizing method, Alternatively, microbubbles are formed by ultrasonic waves, and the microbubbles 11 are dispersed in the hypophosphorous acid aqueous solution 12a.

  Next, the hypophosphorous acid aqueous solution 12 a containing the microbubbles 11 is returned from the plating solution discharge pipe 33 to the heating plating tank 23. Next, similarly to the above, a thin nickel film 12 containing microbubbles 11 is deposited on the object to be plated 1 by electroless nickel plating. According to this method, the thermal barrier film 10 including the microbubbles 11 can be formed in a short time as described above.

  Note that the above manufacturing method is an example, and the present invention is not limited to electroless nickel plating. For example, if the object to be plated 1 on which the thermal barrier film 10 is deposited is limited to a conductive one, electrolytic plating may be performed. A manufacturing method may be used.

  Further, as the microbubble generator 22, a device that generates microbubbles 11 by a method of introducing air from the outside and stirring the gas and liquid, or a gas-liquid shearing method such as a gas-liquid two-phase flow swirl method is used. For example, an apparatus that generates the microbubbles 11 using ultrasonic waves may be used.

Furthermore, without using the microbubble generator 22 or 31 described above, the plating solution 12a in the container (which may be a sealed heating plating tank) is pressurized to dissolve gas such as air and become supersaturated plating. There is also a method in which the microbubbles 11 are generated in the plating solution 12a by reducing the pressure of the solution 12a.

Next, an internal combustion engine according to an embodiment of the present invention will be described with reference to FIG. Here, it is assumed that the object 1 to be plated shown in FIG. 1 is an engine 40, and the combustion section 2 is a combustion chamber 44a. As shown in FIG. 4, the engine 40 includes a cylinder block 41 and the cylinder head 42 comprises a cylinder bore 43, the piston 44, the injector 45, the exhaust passage 46, exhaust valves 47, intake passage 48 and the intake valve 49, .

  The engine 40 includes the above-described heat shield film 10 on a piston top surface portion 44 b including an inner wall of a combustion chamber 44 a formed on the upper surface of the piston 44. According to this configuration, heat generated in the combustion chamber 44a is not transmitted to the piston main body 44c, so that cooling loss can be reduced and fuel efficiency can be improved.

  For example, when the piston 44 is formed by joining an upper structure having a separate combustion chamber 44a and a lower structure joined to the connecting rod shaft, the entire surface of the upper structure is used. If the thermal barrier film 10 is provided on the cooling loss, the cooling loss can be further reduced.

In addition, in order to reduce the cooling loss from the combustion chamber 44a, the thermal barrier film 10 is disposed around the combustion chamber 44a. For more information, it comprises a lower surface of the cylinder head 42, the inner wall surface of the cylinder bore 43, the lower surface of the exhaust valve 47, and the lower surface of the intake valves 49.

  According to this configuration, since heat generated in the combustion chamber 44a can be prevented from being transmitted to the outside of the combustion chamber 44a, cooling loss can be reduced and fuel efficiency can be improved. Further, the thermal barrier film 10 can be easily deposited on the constituent members of the engine 40 by plating, and can be manufactured in a large amount in a short time.

  Furthermore, since the thermal barrier film 10 is formed of the plating film 12, the surface can be made fine and the hardness can be increased. Thereby, the present invention can also be applied to sliding surfaces such as the inner wall surface of the cylinder bore 43. In this embodiment, the thermal barrier film 10 is provided as described above, but may be provided on at least one of the constituent members around the combustion chamber 44a.

  In addition, if the heat shield film 10 is provided on the inner walls of the exhaust manifold 46a and the exhaust pipe 46b of the exhaust passage 46 and the intake manifold 48a and the intake pipe 48b of the intake passage 48, the engine 40 is not heated without heating the intake air. The exhaust gas can be supplied to an aftertreatment device such as DPF (diesel particulate collection filter) with the exhaust gas temperature kept at a high temperature.

The thermal barrier film 10 of the present invention is a metal plating layer having a thin film thickness and a high thermal barrier effect, and is not limited to the engine 40 and can be applied to various devices. For example, the present invention can be applied to turbines and building materials.

  The method for producing a thermal barrier film of the present invention can produce a thermal barrier film capable of reducing heat transfer and shielding heat even in a thin film in a short time and with an easy process. In particular, it can be used for vehicles that are mass-produced.

DESCRIPTION OF SYMBOLS 1 To-be-plated object 2 Combustion part 10 Thermal barrier film 11 Micro bubble 12 Metal plating layer (nickel film)
12a Plating solution 13 Reducing agent 20, 30 Manufacturing device 21 Plating deposition device 22, 31 Microbubble generator 40 Engine (internal combustion engine)

Claims (8)

In the manufacturing method of the thermal barrier film provided with the metal plating layer covering the surface in a state of being laminated on the surface of the object to be plated,
Microbubbles are dispersed inside the plating solution, the object to be plated is plated with the plating solution, and the metal plating layer mainly composed of nickel is encapsulated on the surface of the object to be plated. A method for producing a thermal barrier film, characterized by being deposited.   Air introduced from the outside or vapor generated by reducing the pressure of the plating solution is made into microbubbles, and the microbubbles having a diameter larger than 1 μm and not larger than 10 μm are dispersed inside the plating solution. The method for producing a thermal barrier film according to claim 1. The plating solution of hypophosphorous acid aqueous solution is impregnated with a reducing agent, heated, and the metal plating layer containing the microbubbles is deposited on the object to be plated by electrons released by oxidation of the reducing agent. The manufacturing method of the thermal-insulation film | membrane of Claim 1 or 2 characterized by these. A heat- shielding film comprising a metal plating layer covering a surface of the object to be plated in a state of being laminated , wherein the metal plating layer encloses microbubbles. The thermal barrier film according to claim 4, wherein the metal plating layer having a thickness of 100 μm or less includes the microbubbles having a diameter larger than 1 μm and 10 μm or smaller.   An internal combustion engine comprising the heat shield film according to claim 4 or 5 on at least a part of a piston top surface portion including an inner wall of the combustion chamber.   An internal combustion engine comprising the thermal barrier film according to claim 4 or 5 on at least one of the lower surface of the cylinder head, the lower surface of the exhaust valve, the lower surface of the intake valve, and the inner surface of the cylinder bore around the combustion chamber. organ.   An internal combustion engine comprising the heat shield film according to claim 4 or 5 in at least one of an exhaust manifold, an exhaust pipe, an inlet manifold, and an intake pipe.