JP6361538B2 - Method for adjusting engine combustion chamber volume with thermal barrier film - Google Patents

Description

  The present invention relates to a method for adjusting the volume of an engine combustion chamber with a thermal barrier film.

  In a multi-cylinder engine, it is important to keep the compression ratio of the combustion chamber of each cylinder within a predetermined range. For example, if there is a cylinder with a small compression ratio, the thermal efficiency of the engine will be low. Also, if there is a cylinder with a high compression ratio, the combustion balance between the cylinders is lost, causing vibration and noise. An example of a method for adjusting the combustion chamber volume of an engine for keeping the compression ratio within a predetermined range is described in Patent Document 1. It cuts the mating surface with the cylinder block of the cylinder head obtained by casting, measures the height from this mating surface to the predetermined reference surface of the combustion chamber wall surface of the cylinder head, and burns based on this height The surplus portion provided in advance on the wall surface of the chamber is additionally processed (adjustment of the machining allowance of the surplus portion is adjusted).

  On the other hand, conventionally, there has been known a proposal for improving the thermal efficiency of the engine by forming a thermal barrier film on the combustion chamber wall surface of the cylinder head, the top surface of the piston, or the like. For example, Patent Document 2 describes that a thermal barrier film is formed by applying a paint in which microbubbles are dispersed in a matrix resin to components that form a combustion chamber of an engine.

JP 2011-256730 A JP 2013-189960 A

  However, when a thermal barrier film is formed by applying a thermal barrier material to a combustion chamber forming component of an engine, it is generally difficult to make the thermal barrier film as thick as the design value because of the nature of the application. For this reason, in the engine with a thermal barrier film, the volume of the combustion chamber deviates from the design value, and the compression ratio of the combustion chamber of each cylinder tends to vary. On the other hand, as described in Patent Document 1, it is conceivable to perform additional machining by providing a surplus portion on the combustion chamber wall surface of the cylinder head. However, due to the additional work, the thermal barrier film is partially thinned or the thermal barrier film is partially scraped, resulting in a decrease in the thermal barrier property of the combustion chamber. In addition, there are cases where it is difficult to provide such a surplus portion in design.

  Therefore, an engine with a thermal barrier film is required to keep the compression ratio within a predetermined range while suppressing a decrease in thermal barrier properties. The present invention solves this problem.

  In order to solve the above-mentioned problems, the present invention measures the volume of the combustion chamber forming portion provided with the heat shield film of the cylinder head, and selects a suitable piston based on this, thereby reducing the volume of the engine combustion chamber. I adjusted it.

That is, the method disclosed herein is a method of adjusting the volume of a combustion chamber formed by an engine cylinder head, a cylinder block, and a piston when the piston is at top dead center,
Forming a thermal barrier film on the inner surface of the combustion chamber forming portion forming the combustion chamber in the cylinder head and on at least the top surface of the piston;
Measuring the volume of the combustion chamber forming part having the thermal barrier film of the cylinder head;
Adjusting the volume of the combustion chamber to fall within a predetermined allowable range when the volume of the combustion chamber forming portion is outside the predetermined allowable range,
In the combustion chamber volume adjustment step, a plurality of pistons each having a heat shielding film having a different thickness on the top land and having different outer diameters are prepared. By selecting a piston to be combined with the cylinder head from among them, the volume of the combustion chamber is set within a predetermined allowable range.

According to this method, since the heat shield film is formed on the inner surface of the combustion chamber forming portion of the cylinder head and at least the top surface of the piston, it becomes easy to meet the heat shield requirement of the engine combustion chamber. Then, a plurality of pistons each having a heat shielding film having a different thickness on each top land and having different outer diameters are prepared, and the cylinder head is selected from the plurality of pistons. By selecting the pistons to be combined with each other, the volume of the combustion chamber is kept within an allowable range, so that the compression ratio of each cylinder of the engine can be kept within a predetermined range without impairing the heat shielding property of the engine . Also, a plurality of pistons having different outer diameters of the top lands can be prepared by adjusting the film thickness of the heat shield film, and the preparation becomes simple.

Preferred In one embodiment, in the step of adjusting the volume of the combustion chamber, further, the thermal film barrier of the squish area of the combustion chamber forming part the cylinder head in the child additional machining Thus, the combustion chamber Ensure that the volume falls within a predetermined tolerance. Here, the squish area of the cylinder head is a part that pushes out the air-fuel mixture on the peripheral side of the combustion chamber to the vicinity of the spark plug when the piston comes to the compression top dead center. Thinning of the area heat shield does not significantly affect the thermal efficiency of the engine.

In the step of adjusting the volume of the combustion chamber, further, thus the surface to form a combustion chamber of the piston, and / or the surface forming the combustion chamber of the cylinder block to the child additional machining, the volume of the combustion chamber May fall within a predetermined allowable range. The additional surface may be formed with a heat shield film or without a heat shield film. That is, when a heat shield film is formed on the additional work surface, the heat shield film is cut, and when the heat shield film is not formed on the additional work surface, the main body of the piston and / or cylinder head is removed. Will cut.

One preferred embodiment is previously formed a Saeginetsumaku the upper piston ring in the bore surface of the upper Symbol cylinder block does not strike, in the step of adjusting the volume of the combustion chamber, further, the cylinder block bore Thus the surface top thermal barrier layer to the child additional machining, the volume of the combustion chamber is set to fall within a predetermined allowable range. The formation of the thermal barrier film is advantageous for ensuring the thermal barrier properties of the engine. In this case, even if the heat shield film is thinned by additional work, the heat shield requirement of the piston top land and the bore surface of the cylinder block is low. Here, in other words, “the upper portion where the piston ring does not hit the bore surface of the cylinder block” is a bore surface facing the surface of the piston top land portion when the piston is at the top dead center position.

Preferred are the upper piston ring in the bore surface of the upper Symbol cylinder block does not hit, is that you thicker than previously designed value above Saeginetsumaku.

  That is, when the volume of the combustion chamber forming part of the cylinder head exceeds the upper limit of the allowable range, it is necessary to make up for the excess (adjust to reduce the volume of the combustion chamber). If the thickness of the chamber is as designed, cutting the thermal barrier film will increase the combustion chamber volume beyond the allowable range.

On the other hand, if the thermal barrier film is formed thicker than the design value in advance, it becomes possible to leave the thermal barrier film with a thickness larger than the designed value even after cutting. even if the volume of the parts is larger than the upper limit of the allowable range, Ru can be adjusted to within an allowable range of the combustion chamber volume by cutting Saeginetsumaku.

According to the present invention, when the thermal barrier film is formed on at least the top surface of the combustion chamber forming portion of the cylinder head and the piston, and the volume of the combustion chamber forming portion having the thermal barrier film of the cylinder head is outside a predetermined allowable range. In addition, by selecting a piston to be combined with the cylinder head from a plurality of pistons in which a heat shield film having a different thickness is formed on each top land prepared in advance and the outer diameter of the top land is different , Since the volume of the combustion chamber is set within a predetermined allowable range, the compression ratio of each cylinder of the engine can be set within the predetermined range without impairing the heat shielding property of the engine.

A sectional view showing an engine structure concerning an embodiment of the present invention. The bottom view which shows the combustion chamber formation part of the cylinder head of the same engine. Sectional drawing which shows typically the thermal insulation film | membrane formed in the piston and the cylinder liner. The flowchart which shows the flow of the preparation method which concerns on this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or its use.

<Engine combustion chamber>
A direct injection engine E shown in FIG. 1 is a four-valve engine. In FIG. 1, 1 is a piston, 3 is a cylinder block, 5 is a cylinder head, 7 is a cylinder liner, and 9 is to open and close an intake port 11 of the cylinder head 5. An intake valve, 13 is an exhaust valve that opens and closes the exhaust port 15, and 17 is a fuel injection valve. A cavity 19 is formed on the top surface of the piston 1. A piston ring 21 is fitted on the top of the piston 1. A valve seat 22 is press-fitted into the openings of the intake and exhaust ports 11 and 15.

  Strictly speaking, the combustion chamber of the engine E includes a pent roof type combustion chamber forming portion 10 of the cylinder head 5, a portion extending from the top land 23 to the top surface of the piston 1, and a piston ring 21 on the bore surface of the cylinder liner 7 of the cylinder block 3. Is formed by the upper portion where no contact occurs and the valve head surfaces of the intake and exhaust valves 9 and 13 (surfaces facing the combustion chamber).

  As shown in FIG. 2, a mounting hole 24 for the fuel injection valve 17 is disposed in the center of the cylinder head 5. Although the illustration of the spark plug is omitted, a spark plug mounting hole 29 is provided between the two intake ports 27 of the cylinder head 5. In addition, the code | symbol 25 is an exhaust port and the spark plug attachment hole 29 may be arrange | positioned also between these two exhaust ports 25 and 25. FIG. Further, in the engine E of the present embodiment, two locations around the combustion chamber, that is, outside the two intake ports 27, 27 arranged side by side when viewed from the center of the combustion chamber, and more than the two exhaust ports 25, 25 arranged side by side. On the outside, there are provided half-circle squish areas 30 and 30 for generating a squish flow near the compression top dead center.

  In the engine E, a thermal barrier film is formed on the inner surface of the combustion chamber forming portion 10 of the cylinder head 5 and at least the top surface of the piston 1 in order to increase the thermal efficiency. Preferably, the top land 23 of the piston 1, the upper portion of the bore surface of the cylinder liner 7 where the piston ring 21 does not contact (the bore surface facing the top land 23 of the piston 1), and / or the valve heads of the intake and exhaust valves 9, 13. A thermal barrier film is also formed on the surface.

  FIG. 3 schematically shows, as an example, the heat shield film 31 formed on the top surface of the piston 1 and the top land 23 and the upper portion of the bore surface of the cylinder liner 7 where the piston ring 21 does not contact. In the figure, 33 is a piston ring groove. The thermal barrier film 31 is formed by dispersing a number of inorganic oxide hollow particles in a matrix resin (silicone).

<Adjustment method of combustion chamber volume>
Hereinafter, a method for adjusting the volume B of the combustion chamber when the piston 1 is at the top dead center will be described. The basic flow is as shown in FIG.

[Processing of combustion chamber forming section] (Step S1)
The inner surface of the combustion chamber forming portion 10 of the cylinder head 5 (the surface forming the combustion chamber) is machined. That is, the entire inner surface is processed except for the valve seat press-fitting portions of the intake port 27 and the exhaust port 25.

[Formation of thermal barrier film] (Step S2)
A heat shielding film 31 is formed on the inner surface of the combustion chamber forming portion 10 of the cylinder head 5 and at least the top surface of the piston 1. That is, the thermal barrier film 31 is formed by applying a thermal barrier material in which a large number of inorganic oxide hollow particles are dispersed in a matrix resin material to the thermal barrier film forming portion and heating and curing the matrix resin material. To do . Also formed a Saeginetsumaku to the top land 23 of the piston 1. In this case, in order to adjust the combustion chamber volume B, which will be described later, a plurality of pistons 1 each having a heat shielding film having a different thickness on the top land 23 and having different outer diameters are prepared. To do. If necessary, a heat insulating film is also formed on the upper surface of the bore surface of the cylinder liner 7 where the piston ring 21 does not contact.

[Measurement of volume of combustion chamber forming section] (step S3)
The volume A of the combustion chamber forming part 10 having the heat insulating film of the cylinder head 5 is measured. For example, the height h from the mating surface of the cylinder head 5 with the cylinder block 3 to a predetermined portion of the combustion chamber forming portion 10 is measured, and the opening area S and the predetermined coefficient K of the combustion chamber forming portion 10 are measured at this height h. Is multiplied by the volume A of the combustion chamber forming portion 10.

  Alternatively, the position coordinate of a plurality of points set on the inner surface of the combustion chamber forming unit 10 is obtained by a contact type three-dimensional measuring machine, and the volume from the combustion chamber volume on the design data based on the deviation of the position coordinate from the design data. An error amount may be calculated, and the actual volume A of the combustion chamber forming unit 10 may be obtained based on the error amount. Alternatively, the volume A may be obtained by a non-contact position sensor using laser or ultrasonic waves, or the volume A may be obtained by photographing the combustion chamber forming unit 10 and performing image processing thereof.

[Volume determination] (step S4)
It is determined whether or not the volume A of the combustion chamber forming unit 10 is within a predetermined allowable range (within a preset upper limit value and lower limit value range). When the volume A of the combustion chamber forming portion 10 is within the permissible range, the process proceeds to step S5, and the piston 1 whose dimensions are within the predetermined permissible range is selected and combined with the combustion chamber forming portion 10. Thus, the volume B of the combustion chamber is kept within a predetermined allowable range.

  When the volume A of the combustion chamber forming unit 10 is outside the allowable range, the process proceeds to the step of adjusting the volume B of the combustion chamber in step S6.

[Adjustment of combustion chamber volume B] (step S6)
The method of adjusting the combustion chamber volume B, there are three of the following (a) to (c). By selecting an appropriate piston in ( c ) as an indispensable adjustment method, if necessary, by executing any one of (i) to ( b ) additional processes or a combination of multiple additional processes, The combustion chamber volume B is set within a predetermined allowable range. That is, the combustion chamber volume B is brought close to the permissible range by the additional processes (A) to ( B ), and the compatible piston is selected ( C ). The volume B may be within an allowable range.

  (A) The heat shield film in the squish area 30 of the combustion chamber forming portion 10 of the cylinder head 5 is cut by additional machining.

This is a technique that can be taken when the volume A of the combustion chamber forming portion 10 is smaller than the lower limit value of the allowable range. The volume A is increased by cutting the thermal barrier film of the squish area 30 and the combustion chamber volume B is allowed. It becomes easy to fit in the range. Since the squish area 30 is a portion having a low heat shielding requirement, it is possible to avoid the heat insulation performance of the engine E from being greatly impaired by cutting the heat shielding film .

If the volume A of the combustion chamber forming portion 10 is within the allowable range, the piston 1 a thermal film barrier of the top land 23 is thicker than the design value is not used, the dimensions within a predetermined tolerance By combining a certain piston 1, the volume B of the combustion chamber falls within a predetermined allowable range.

( B ) The thermal barrier film on the upper part of the cylinder liner 7 is cut by additional machining.

  That is, when the volume A of the combustion chamber forming portion 10 is smaller than the lower limit value of the allowable range, the volume A is increased by cutting the thermal barrier film of the cylinder liner 7 and the combustion chamber volume B can be easily kept within the allowable range. become. Since the cylinder liner 7 is a portion having a low degree of heat shielding requirement, it is possible to avoid that the heat insulation performance of the engine E is greatly impaired in this case as well.

  In the additional work of the heat shield film of the cylinder liner 7, the heat shield film can be formed thicker in advance than the design value. In this case, when the volume A of the combustion chamber forming portion 10 is smaller than the lower limit value of the allowable range, the thermal barrier film of the cylinder liner 7 is cut so as to be thinner than the design value. On the other hand, when the volume A of the combustion chamber forming portion 10 is larger than the upper limit value of the allowable range, the thermal barrier film of the cylinder liner 7 is cut in a range that does not become thinner than the design value.

  However, when the thermal barrier film of the cylinder liner 7 is thicker than the design value in advance, the thermal barrier film of the cylinder liner 7 is set to the designed thickness even when the volume A of the combustion chamber forming portion 10 is within the allowable range. It is necessary to cut so that it becomes.

( C ) The piston 1 that matches the volume A of the combustion chamber forming portion 10 is selected.

As described above, a plurality of pistons 1 are prepared in which heat shield films having different thicknesses are formed on the top lands 23 so that the outer diameters of the top lands 23 are different. Then, by selecting a piston 1 that matches the volume A of the combustion chamber forming portion 10 from the plurality of pistons 1 and combining it with the combustion chamber forming portion 10, the combustion chamber volume B is within an allowable range.

The above (b) at has been such that additional machining heat membrane barrier of shea Rindaraina 7, even cylinder liners is not formed Saeginetsumaku, or cylinder block provided with no cylinder liner Even if it exists, the combustion chamber volume B can be accommodated in a tolerance | permissible_range by adding the upper part of the bore surface .

Also, the a (i) (ii) is combined can also be performed. For example, by performing squish additional machining of Saeginetsumaku area by (a) above with a larger volume A little additional machining of Saeginetsumaku of the cylinder liner and (b), allows the combustion chamber volume B range You may make it fit in.

Further, in the above embodiment employs a technique called application of thermal barrier material to the formation of Saeginetsumaku, forming a thermal film barrier by spraying the heated material shielding of ZrO ₂ such as Saeginetsumaku forming section In the present invention, the method for forming the thermal barrier film is not limited.

E Engine 1 Piston 3 Cylinder block 5 Cylinder head 7 Cylinder liner 10 Combustion chamber forming part 23 Topland 30 Squish area 31 Thermal barrier film

Claims (4)

A method of adjusting the volume of a combustion chamber formed by an engine cylinder head, a cylinder block and a piston when the piston is at top dead center,
Forming a thermal barrier film on the inner surface of the combustion chamber forming portion forming the combustion chamber in the cylinder head and on at least the top surface of the piston;
Measuring the volume of the combustion chamber forming part having the thermal barrier film of the cylinder head;
Adjusting the volume of the combustion chamber so that the volume of the combustion chamber falls within a predetermined allowable range when the volume of the combustion chamber forming portion is outside the predetermined allowable range,
In the combustion chamber volume adjustment step, a plurality of pistons each having a heat shielding film having a different thickness on the top land and having different outer diameters are prepared. A method for adjusting the volume of an engine combustion chamber with a thermal barrier film, wherein the piston combined with the cylinder head is selected so that the volume of the combustion chamber falls within a predetermined allowable range. In claim 1,
In the step of adjusting the volume of the combustion chamber, further, the thermal film barrier of the squish area of the combustion chamber forming part of the cylinder head and the child alteration Thus, the volume of the combustion chamber is within a predetermined tolerance A method for adjusting the volume of an engine combustion chamber with a thermal barrier film. In claim 1 or claim 2,
The top piston ring is not exposed at the bore surface of the upper carboxymethyl cylinder block previously formed a Saeginetsumaku,
In the step of adjusting the volume of the combustion chamber, further, thus the thermal film barrier of the bore surface top of the upper carboxymethyl cylinder block and child additional machining, the volume of the combustion chamber is set to fall within a predetermined allowable range A method for adjusting the volume of an engine combustion chamber with a thermal barrier film. In claim 3,
The upper piston ring is not exposed in the bore surface of the upper carboxymethyl cylinder block, adjusting method of the thermal barrier layer with an engine combustion chamber volume, characterized in that to be thicker than the pre-designed value above Saeginetsumaku.

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