JP5864016B2 - Compression ring for internal combustion engine - Google Patents

Description

  The present invention relates to a compression ring for an internal combustion engine.

  2. Description of the Related Art Conventionally, in internal combustion engines such as engines, engine oil is heated with long-time operation and exposed to blow-by gas, so that unburned products of hydrocarbons and modified products of oil additives in engine oil. Will be mixed. In a diesel engine, carbon fine particles are also mixed in the engine oil. In general, such unburned products, modified oil additives and fine carbon particles are generally referred to as “oil sludge”.

  If this oil sludge accumulates and adheres to the compression ring that is a part of the piston ring, especially the inner peripheral side that is the piston facing surface (see FIG. 1), the movement of the compression ring is impaired and blow-by gas increases. As a result, the engine function may be degraded, such as a reduction in fuel consumption or output.

  In particular, in a diesel engine or an internal combustion engine with a high in-cylinder pressure, the compression ring cross-sectional shape may be changed from a rectangular shape to a keystone shape (see FIG. 2) so that the mobility of the compression ring is not impaired by oil sludge. Has been done.

  In addition, Patent Document 1 discloses the inclination angle of the upper surface of a compression ring having a rectangular cross-sectional shape in order to improve gas sealing performance and oil consumption performance while suppressing oil sticking to the compression ring. A technique for varying the direction is disclosed.

JP 2004-197857 A

  In the compression ring, a certain effect of suppressing the adhesion of oil sludge is recognized by making its cross section into a keystone shape, or by changing the shape as described in Patent Document 1. However, in recent years, engines have been used at high speeds, for example, in high temperature ranges under severe usage conditions, and even in such an environment, it is possible to provide a means that can reliably prevent oil sludge from adhering to the compression ring. Is sought after.

  Therefore, an object of the present invention is to provide a compression ring for an internal combustion engine that can more reliably suppress the adhesion of oil sludge to the compression ring as compared with the conventional case.

  The inventor diligently investigated the means for solving the above problems, and as a result of examining the constituent components other than the hydrogen bonding component with respect to the surface free energy of the solid and the liquid, the constituent components of the dispersed component, the polar component, and the hydrogen bonding component were determined. It was found that the difficulty of adhesion between a solid (compression ring) and a liquid (engine oil) can be evaluated with a cohesive energy density of.

  Then, it came to the idea to apply the HSP value defined by Hansen that refers to the cohesive energy density for each component of the surface free energy. In this Hansen's HSP value, in evaluating the adhesion and compatibility between substances, it has been successful to use the difference in dispersion component, polar component, and hydrogen bonding component between liquids or between liquid / resin, This time, the present invention will be led by building a new relationship between a solid-liquid containing metal, especially a compression ring, which is often made of a metal base material, and an engine oil with a complex composition. It was.

The gist of the present invention is as follows.
(1) The compression ring for an internal combustion engine of the present invention has a surface free energy (unit area (mJ / m) at 80 ° C. in at least a part of the substrate surface constituting the outer surface of the compression ring (excluding PTFE). ² ) Dispersion component, polar component, and hydrogen bond component constituting δ) are δ _d1 , δ _p1 , and δ _h1 respectively, and the surface free energy (per unit area (mJ / m ² )) of engine oil at 80 ° C. When the dispersive component, the polar component, and the hydrogen bond component are δ _d2 , δ _p2 , δ _h2 (δ _d2 = 38.9, δ _p2 = 13.6, δ _h2 = 0.0), respectively, the following formula A Ε defined by the above is 8 or more.
[Formula A]

  According to the compression ring for an internal combustion engine having such a configuration, it is possible to provide a compression ring that can more reliably suppress the adhesion of oil sludge as compared with the conventional one.

  The “surface free energy” in the present invention is the total sum of a polar component, a dispersive component and a hydrogen bond component consisting of intermolecular forces according to the extended Fowkes equation.

(2) In the compression ring for internal combustion engines of this invention, it is preferable to surface-treat the said base material surface.

(3) In the compression ring for an internal combustion engine of the present invention, the surface roughness of the substrate surface is preferably 0.0050 μm or more and 0.40 μm or less in terms of centerline average roughness.
In addition, the surface roughness in this invention is based on JISB0601: 2001.

  According to the present invention, it is possible to provide a compression ring for an internal combustion engine that can more reliably suppress oil sludge from adhering to the compression ring as compared with the conventional case.

FIG. 5 is a schematic cross-sectional view showing a state where oil sludge is accumulated and fixed in a piston with a compression ring assembled thereto. It is sectional drawing of a compression ring of a keystone shape. It is a figure which shows the correlation with various coating | covering materials and oil sludge adhesion amount. It is a figure which shows the component of the surface free energy of various engine oil. It is sectional drawing of the adhesion tester used in the Example of this invention. It is a figure which shows the adhesion amount of oil sludge.

Hereinafter, the compression ring for internal combustion engines of the present invention will be described in detail.
In the compression ring for internal combustion engines (excluding PTFE) according to the present invention, as described above, the surface free energy (unit area (unit area)) of at least a part of the substrate surface constituting the outer surface of the compression ring. per mJ / m ² )), and the surface free energy (unit area (mJ / m ² )) of the engine oil at 80 ° C. is defined as δ _d1 , δ _p1 , and δ _h1 , respectively. ) _D2 , δ _p2 , δ _h2 (δ _d2 = 38.9, δ _p2 = 13.6, δ _h2 = 0.0) It is important that ε defined by the following formula A is 8 or more.
[Formula A]

Here, in FIG. 3, the experimental results obtained in Example 1 to be described later, that is, the results of evaluating the difficulty of oil sludge adhering to various substrates and coating materials, the amount of oil sludge adhering on the vertical axis ( mg / cm ² ), as shown by taking ε represented by the above formula A on the horizontal axis, if ε is 8 or more, the amount of oil sludge adhering to the compression ring is suppressed to less than 8 mg / cm ^2. I understood that. That is, it is excellent against oil sludge by using a base material having a surface free energy where ε is 8 or more, or by covering at least a part of the compression ring with a coating material having the same surface free energy. Adhesion resistance is obtained.

  In order to achieve higher adhesion resistance to oil sludge, ε represented by the above formula A is preferably 13 or more, and more preferably 15 or more.

  The three components of the surface free energy of the compression ring substrate or coating material, that is, the dispersion component, the polar component, and the hydrogen bonding component, use a liquid whose surface free energy is known, and the substrate or coating with an automatic contact angle meter The contact angle of the coating surface with the material can be measured and calculated by the extended Fowkes equation.

  In addition, the three components of engine oil surface free energy are measured by measuring the contact angle between a solid material with a known surface free energy calculated by the extended Fowkes equation and the engine oil. From the expanded Fowkes equation and the experimental equations of Sell and Newmann Can be calculated.

  Furthermore, in the compression ring for an internal combustion engine according to the present invention, it is preferable that the covering material is a metal or a resin. Specific examples include Ni, Mo, Co, PTFE, PFA and FEP, and alloys or compounds containing them. What is important in the present invention is a material in which ε represented by the above formula A is 8 or more. The predetermined part of the compression ring is formed of a covering material or a base material.

  As a method for coating a material, generally, if it is a metal, a wet electrolysis method, a wet electroless method, a vacuum deposition method, a chemical conversion treatment method, PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), or AD (Aerosol Deposition) In the case of a resin, a dipping method, a spray method, a spin coating method, and the like can be used. In the present invention, any coating method can be employed.

Moreover, in the compression ring which concerns on this invention, it is preferable that the thickness of the film by a coating material is 0.1 micrometer or more and 8.0 micrometers or less.
If the thickness of the coating is 0.1 μm or more, the occurrence of film defects can be avoided and the coating with ε of 8 or more can be stably obtained, so that oil sludge adhesion can be more reliably suppressed. . On the other hand, when the thickness of the coating exceeds 8.0 μm, it is possible to obtain an excellent effect in suppressing the adhesion of oil sludge, but there is a concern about an increase in cost required for coating. Therefore, the upper limit value is preferably set to 8.0 μm.

  In addition, the compression ring according to the present invention can be formed by subjecting at least a part of the outer surface of the ring to surface treatment. Examples of the surface treatment herein include cleaning / rust prevention treatment, heat treatment (for example, Including atmospheric heat treatment, inert gas atmosphere heat treatment, carburizing treatment, nitriding treatment, sulfurating treatment, etc.) or polishing. As a method other than using a rust preventive agent, there is a method of performing a fluorination treatment on the compression ring surface with ArF2 gas.

  Furthermore, in the compression ring according to the present invention, the surface roughness of the compression ring is preferably 0.0050 μm or more and 0.50 μm or less in terms of center line average roughness. By making the surface roughness of the compression ring within this range, the effect of suppressing the adhesion of oil sludge to the compression ring is enhanced. The lower limit is set to 0.0050 μm, but the effect of suppressing the adhesion of oil sludge increases as the surface roughness is small. However, if the surface roughness is less than 0.0050 μm, the improvement in the effect cannot be matched to the cost required for processing. It is. Moreover, the said effect can fully be heightened by making the surface roughness of a film into 0.50 micrometer or less.

As shown in FIG. 1, oil sludge (the black portion in the figure) tends to accumulate in the back clearance between the inner peripheral side of the compression ring 1 and the piston 2. Therefore, the surface F ₁ that opposes the piston 2 of the compression ring ₁ , that is, the inner peripheral surface of the compression ring ₁ , is formed of a base material or a coating material having an ε of 8 or more represented by the above formula A, thereby Adhesion can be suppressed.

  In addition, since the material having ε of 8 or more is formed on the entire surface of the compression ring by the base material or the covering material, it is possible to more effectively suppress the adhesion of oil sludge to the compression ring.

Hereinafter, based on an Example, this invention is demonstrated further more concretely.
First, each component of the surface free energy of three types of solid materials required for measuring the surface free energy of engine oil was determined. Cu, Al, and Ni were selected as solid materials. Each component can be calculated by determining the contact angle between the liquid and the solid. The contact angle was measured with DM-501 of Kyowa Interface Chemical Co., Ltd., and each component of the surface free energy was calculated using the extended Fowkes equation with FAMAS of add-in software. The surface roughness of the solid material was polished with emery polishing paper so that the center line average roughness was 0.10 μm or more and 0.20 μm or less. The probe droplet was about 1 μL. Table 1 shows the constituents of the probe liquid and surface free energy (theoretical values at 25 ° C.), and Table 2 shows the constituents calculated as solid materials. In addition, all the measurement of the surface free energy in this embodiment was performed at 80 degreeC.

  DM-501 of Kyowa Interface Chemical Co., Ltd. has contact angles with the solid materials shown in Table 2 for new engine oil that is expected to be used and engine oil circulated in the engine under a certain load. Each component of the surface free energy of the engine oil was calculated from the extended Fowkes equation and the Sell and Newmann empirical equations (see Table 3). The engine oil sold by each company was selected, and the probe droplet was about 1 μL.

[Calculation example]
In order to obtain each constituent component, the surface free energy γ _L of the oil I is obtained.
From the existing Dupre formula,
From Sell and Newmann's empirical formula,
From equation (1)
Is established.
From the Young-Dupre formula,
From equations (3) and (4),
Γ _L is obtained by substituting γ _S and the contact angle θ obtained by measurement into equation (5).
Example) Cu free surface energy: γ _L ^Cu is determined from the contact angle θ between γ _S and oil I.
γ _S = 48.7 θ = 31.5
Substituting into equation (5),
Solving this, γ _L ^Cu = 56.3, 201.6
Compared with other findings (γ _{L of} paraffins), 201.6 is not possible.
Therefore, γ _L ^{Cu of} oil I calculated from ^Cu is 56.3.
Similarly, when γ _L is calculated from Al and Ni, they are 37.2 and 34.8, respectively.

The surface free energy of the oil I is obtained from the contact angles θ, γ _L of Cu, Al, and Ni (using values calculated from the respective solid surfaces).
Cu: θ = 23.7 γ _L ^Cu = 56.3 γ _S ^d = 32.7 γ _S ^p = 16.0 γ _S ^h = 0
Al: θ = 19.3 γ _L ^Al = 37.2 γ _S ^d = 35.3 γ _S ^p = 1.2 γ _S ^h = 1.1
Ni: θ = 20.9 γ _L ^Ni = 34.8 γ _S ^d = 35.4 γ _S ^p = 0 γ _S ^h = 0
Cu, Al, Ni, d, p, and h are displayed to represent each component.
Here, the extended Fowkes formula is shown in (6).
Substituting each numerical value,
Solve the ternary linear equation consisting of Eqs. (7) to (9),
From γ _L ^d = 32.0 γ _L ^p = 29.2 γ _L ^h = 0 (0 because it is an imaginary solution), γ _L = 61.2

FIG. 4 and Table 3 show the results of calculating the constituent components of the surface free energy of various engine oils. As described above, almost no variation due to the viscosity of the oil manufacturer or the oil was recognized for each component of the surface free energy of the engine oil. Therefore, in calculating the surface free energy of the metal or resin material covering the compression ring, the average value of various engine oils was used as each component of the surface free energy of the engine oil. That is, the dispersion component γ _L ^d = 38.9 mJ / m ² , the polar component γ _L ^p = 13.6 mJ / m ² , and the hydrogen bonding component γ _L ^h = 0 mJ / m ² were used.

  Next, each component of the surface free energy at 80 ° C. was determined for a total of 16 types of plate materials and plate materials obtained by subjecting steel materials to surface treatment that were relatively easy to obtain. As described above, each component can be calculated by determining the contact angle between the liquid and the solid. The contact angle was measured with DM-501 of Kyowa Interface Chemical Co., Ltd., and each component of the surface free energy was calculated using the extended Fowkes equation with FAMAS of add-in software.

  For the plate material, carbon steel (C: 0.8 to 0.9 mass%), Si—Cr steel (Si: 1.2 to 1.6 mass%, Cr: 0.5 to 0.8 mass%), SUS304, SUS440B, Cr steel (Cr: 12-14 mass%), Ti, Co, Mo, and PTFE were selected. For Si-Cr steel (with surface treatment), SUS440B (with surface treatment), Cr steel (with surface treatment), ultrasonic cleaning with ethyl alcohol was performed for 5 minutes as a cleaning, and then alkyl as an organic component. It was treated for 1 minute using a rust preventive agent containing alkoxysilanes, pulled up and dried at 120 ° C. for 30 minutes.

  For plating of the plate material, Ni-P alloy plating containing 10% of Cu and P, metal Ni plating (purity 99 mass%), and Ni plating in which PTFE was dispersed were selected. The surface roughness of the solid material was polished with emery polishing paper so that the center line average roughness was 0.10 μm or more and 0.50 μm or less. The probe droplet was about 1 μL. Table 4 shows the components of the probe liquid and surface free energy, and Table 5 shows the results of calculating the components.

  Here, in order to confirm the ease of adhesion of oil sludge, a simple adhesion test was performed. Various plate materials were processed to about 30 × 15 × 1 t to prepare test pieces with φ3 holes, and the weight before the test was measured. Then, with respect to the test piece suspended from the adhesion tester shown in FIG. 5, the oil bath filled with engine oil containing oil sludge (shown in Table 3, equivalent to a company D <1> running of approximately 200,000 km) is used. The oil sludge was fixed to the test piece by repeating 50 cycles of immersion for 1 minute and oil fixation for 15 minutes by indirect heating using a heater. The time required for 50 cycles was about 14 hours. The test piece temperature was measured with a thermocouple, and the heater temperature was set so that the temperature range was 190 to 200 ° C. After the test, ultrasonic cleaning was performed with acetone, and the oil sludge adhesion weight was measured.

  In the adhesion tester shown in FIG. 5, after immersing the test piece in an oil bath, the test piece is pulled up by a motor and placed in a cylindrical heater. Temperature monitoring was performed on each of the heater surface and the sample surface.

From Table 5 above, the magnitude was calculated using a method of comparing the difference in cohesive energy density defined by the HSP value. The dispersion component, polar component, and hydrogen bonding component constituting the surface free energy (per unit area (mJ / m ² )) at 80 ° C. of the solid material are assumed to be δ _d1 , δ _p1 , and δ _h1 , respectively. The dispersive component, the polar component, and the hydrogen bond component constituting the surface free energy (per unit area (mJ / m ² )) are substituted into the equation A as δ _d2 , δ _p2 , and δ _h2 respectively.
[Formula A]

Table 6 shows the value of ε and the oil sludge adhesion weight per unit area. FIG. 3 shows the correlation between ε and the oil sludge adhesion weight per unit area. As shown here, in the base material and the coating material in which ε is 8 or more, the adhesion amount of oil sludge is significantly reduced as compared with other base materials and the coating material. In the present invention, the case where the oil sludge adhesion amount per unit area was less than 8.0 mg / cm ² was evaluated as the oil sludge adhesion amount being sufficiently small. Furthermore, in the metal or resin material in which ε is 13 or more, the amount of oil sludge attached is reduced to less than 2.0 mg / cm ² , and in particular, in the metal or resin material in which ε is 15 or more, oil sludge It can be seen that the adhering amount of is further reduced to less than 1.0 mg / cm ² . That is, when at least a part of the outer surface of the compression ring is set to ε of 8 or more, preferably 13 or more, more preferably 15 or more in the above formula A, excellent adhesion resistance to oil sludge is obtained. It is done.

  In the present invention, the material itself selects and uses the material satisfying ε defined in the present invention, or the numerical values of the dispersive component, the polar component and the hydrogen bond component constituting the surface free energy are By dispersing a material that is significantly lower or significantly higher than that of the surface free energy of the oil, for example in the plating covering the compression ring, ε is 8 or more, preferably 13 or more, more preferably 15 or more. It can be.

With respect to the electrolytic Ni plating material and martensitic stainless steel for which excellent adhesion resistance was obtained in Example 1, the sludge deposition weight was evaluated with an actual engine. A compression ring was produced as follows. None of the compression rings is subjected to the surface treatment described in paragraph 0041.
This time, the top ring was evaluated. The top ring was fabricated by forming a martensitic stainless steel with a width of 2.3 mm and a thickness of 1.0 mm into an annular shape, cutting the outer periphery with a Cr-based ion plating process, and performing an outer peripheral lapping and buffing process. .
As a comparative example, for # 4, Si-Cr steel having a width of 2.3 mm and a thickness of 1.0 mm was formed and cut into an annular shape, and Cr-based ion plating treatment was applied to the outer periphery to obtain an outer peripheral wrap and buff. It was produced through a finishing process.
In # 1, the outer peripheral surface was masked with a plating masking agent, and then coated with 3 to 5 μm of Ni by electrolytic Ni plating.
Furthermore, in # 2, after masking the outer peripheral surface with a masking agent for plating, a general nickel strike bath (wood bath) is constructed, and a ground treatment is performed with a current density of 20 A / dm ² and a treatment time of 1 minute. A dispersion nickel plating bath was constructed with Tefjit manufactured by JCU Co., Ltd. to coat 3-5 μm Ni-PTFE dispersion plating.

  These compression rings were mounted on a gasoline direct injection type 1,300 cc, in-line 4-cylinder water-cooled engine with a cylinder inner diameter of 72.5 mm, and durability operation combining acceleration and deceleration was carried out. In addition, the oil sludge adhesion state and weight in the top ring and piston groove were confirmed. Table 7 and FIG. 6 show the results of the oil sludge adhesion weight accumulated in the top ring and the piston groove.

A compression ring for an internal combustion engine that is coated or surface-modified with a coating material, wherein the surface free energy (unit area (mJ / m ² ) at 80 ° C. of at least a part of the compression ring, particularly the piston facing surface The dispersive component, polar component, and hydrogen bond component constituting the permissible component are defined as δ _d1 , δ _p1 , and δ _h1 , respectively, and the surface free energy (per unit area (mJ / m ² )) of the engine oil at 80 ° C. When the dispersion component, the polar component, and the hydrogen bonding component are δ _d2 , δ _p2 , and δ _h2 , respectively, ε defined by the above equation A is 8 or more. Obtained.

Claims (2)

In a compression ring for an internal combustion engine , at least a part other than the outer peripheral surface of the base material surface constituting the outer surface of the compression ring (excluding PTFE) is subjected to a surface treatment . The dispersion component, polar component, and hydrogen bond component constituting the surface free energy (per unit area (mJ / m ² ) at 80 ° C. are defined as δ _d1 , δ _p1 , and δ _h1 , respectively. Dispersion component, polar component, and hydrogen bond component constituting surface free energy (per unit area (mJ / m ² )) are δ _d2 , δ _p2 , δ _h2 (δ _d2 = 38.9, δ _p2 = 13.6, respectively). , Δ _h2 = 0.0), a compression ring for an internal combustion engine, wherein ε defined by the following formula is 8 or more.
[Formula A]
2. The compression ring for an internal combustion engine according to claim 1 , wherein the surface roughness of the substrate surface is 0.0050 μm or more and 0.40 μm or less in terms of center line average roughness.