JP6142862B2 - Sliding structure - Google Patents

Description

  The present invention relates to a sliding structure in which a plurality of sliding members are combined in an internal combustion engine (rotary piston engine) of an automobile.

  Conventionally, for example, a combination of an apex seal in a rotary piston engine and a groove formed on the top of the rotor that stores the apex seal, a combination of a vane in the compressor and a rotor groove that stores the vane, or a piston groove and a piston ring in a reciprocating engine In the combination of the above, technological development for improving both wear resistance has been advanced.

For example, in Patent Document 1, a Ti-6Al-4V alloy rotor is oxidized and heat treated at 640 ° C. to 800 ° C. to form a TiO ₂ film, and both wear resistance is ensured in combination with a cast iron apex seal. The technology is described. Patent Document 2 describes a technique for improving the wear resistance of a groove portion that accommodates an apex seal by heat-treating a cast iron rotor.

JP-A-56-126623 JP 2004-162152 A

  However, the one described in Patent Document 1 is not practical in terms of cost because an expensive Ti alloy is used as a rotor and heat treatment at high temperature is required.

  Moreover, since the cast iron apex seal described as an Example in patent document 1 also has sliding with the Cr plating layer which forms the trochoidal surface of a rotor housing, it ensures the wear resistance of a cast iron apex seal. Is difficult.

  In this regard, the cast iron apex seal is made to have a high hardness by chilling the vicinity of the top of the R-shaped section that slides with the Cr plating layer on the trochoidal surface.

  Then, by the chilling treatment, the wear resistance of the apex seal is ensured for sliding with the Cr plating layer of the trochoid surface, while the base portion made of the cast iron structure of the apex seal and the chilled chill portion Both of them slide with the rotor groove, and it becomes necessary to ensure the wear resistance of the rotor groove with respect to both the base portion and the chill portion.

  Furthermore, in recent years, weight reduction of the engine has become an important issue. Especially in the case of a rotary piston engine, if the weight of the rotor, which is the main component, is reduced, the engine speed (torque) can be increased. / Output / fuel consumption) can be improved. Therefore, in place of the cast iron rotor described in Patent Documents 1 and 2 that have been mass-produced so far, there is a demand for practical use of an aluminum alloy rotor.

  However, the aluminum alloy has a lower hardness than cast iron. For example, even a high hardness alloy obtained by treating the cast AC4B material with T6 has a hardness (Vickers hardness) of about Hv130. Therefore, when a base material made of an aluminum alloy is simply used as the rotor, as described above, the rotor slides with the apex seal having the base portion (about Hv400) of the cast iron structure and the chilled chill portion (about Hv600). There is a concern that the wear of the groove progresses and the gas sealability deteriorates. For this reason, it is necessary to ensure higher wear resistance of the rotor groove.

  As described above, the present invention improves wear resistance in a sliding structure in which a first sliding member such as an aluminum alloy rotor is combined with a second sliding member such as an apex seal housed in the rotor groove. And ensuring high durability and reliability.

In order to solve the above problems, in the present invention, a coating made of TiO ₂ is formed on the surface of the base material of the first sliding member and on the sliding contact surface with the second sliding member.

That is, the sliding structure disclosed here is a combination of a first sliding member having a base material made of an aluminum alloy and a second sliding member made of cast iron that slides relative to the first sliding member. The first sliding member has a coating made of TiO ₂ on the sliding contact surface with the second sliding member on the surface of the base material, and the second sliding member And a base portion made of a cast iron structure and a chill portion formed by chilling the cast iron structure.

As described above, since the aluminum alloy has a lower hardness than cast iron, the first sliding member wears when the second sliding member slides. Therefore, according to the present invention, by forming a hard TiO ₂ film on the sliding surface of the first sliding member with the second sliding member, both the base portion and the chill portion of the second sliding member With respect to the sliding, the wear resistance of the first sliding member can be improved, and a sliding structure with high durability and reliability can be obtained.

  The film thickness of the film is preferably 5 μm or more and 15 μm or less, and particularly preferably 5 μm or more and 10 μm or less. Further, the hardness of the film is preferably Hv500 or more and Hv800 or less, particularly preferably Hv600 or more and Hv800 or less. In a preferred embodiment, the film thickness is 5 μm or more and 15 μm or less, and the film hardness is Hv500 or more and Hv800 or less. In a particularly preferred embodiment, the film thickness is 5 μm or more and 10 μm or less, and the film hardness is Hv600 or more and Hv800 or less. Thereby, while ensuring the excellent wear resistance of the first sliding member, it is possible to bring about a sliding structure excellent in the balance between both by suppressing the increase in the attacking of the opponent, and improving the durability reliability of the sliding structure. It can be improved further.

The porosity of the pre-Symbol coating 5. It is 5% or more and 10% or less, more preferably 6.0% or more and 9.5% or less, and particularly preferably 6.4% or more and 9.2% or less. As a result, the oil retaining property of the TiO ₂ film is kept good and the oil supply property to the sliding contact surface is increased, so that the wear resistance of the sliding structure is effectively improved.

In another embodiment, the surface roughness of the pre-Symbol film, not less than R a0.4μm Ra1.2μm, particularly preferably not more than Ra1.0μm least Ra0.4Myuemu. Thereby, the other party aggression property to the said 2nd sliding member can be suppressed effectively, maintaining favorable oil supply property.

  In a preferred embodiment, the chill portion of the second sliding member can slide with respect to the third sliding member.

  The present invention can be applied to a sliding structure formed by combining sliding members in a rotary piston engine, a reciprocating engine, a compressor, and the like. Particularly preferably, the present invention can be applied to a sliding structure of a rotary piston engine, that is, a combination of an apex seal and a groove on the top of the rotor that houses the apex seal.

  Therefore, in a preferred embodiment, the first sliding member is a rotor of a rotary piston engine having a groove at the top, and the second sliding member is an apex seal housed in the groove.

  The third sliding member is preferably a rotor housing of the rotary piston engine.

  The base and chill part of the second sliding member may be configured such that a part of a single member made of cast iron structure is chilled to form a chill part, or a member made of cast iron structure And another member made of a chill structure may be integrally joined.

As described above, according to the present invention, the base of the second sliding member and the chill are formed by forming a hard TiO ₂ film on the sliding contact surface of the first sliding member with the second sliding member. With respect to sliding with both parts, the wear resistance of the first sliding member can be improved, and a sliding structure with high durability and reliability can be obtained. Further, by adjusting the film thickness of the TiO ₂ film, the hardness of the film, the porosity and / or the surface roughness of the film surface can be controlled, so the wear resistance of the first sliding member is improved. In addition, it is possible to obtain a sliding structure with higher durability and reliability by suppressing an increase in the attacking property of the first sliding member relative to the second sliding member.

FIG. 1 is a sectional view schematically showing a rotary piston engine to which the present invention is applied. FIG. 2 is an enlarged view of the apex seal shown in FIG. 1, and (a) is a diagram for explaining how the apex seal accommodated in the rotor groove slides against the trochoidal surfaces of the rotor and the rotor housing. b) is a diagram showing a configuration of an apex seal. FIG. 3 is a diagram for explaining a method of forming a TiO ₂ film by plasma electrolytic deposition. FIG. 4 is a (a) plan view and (b) side view of a disk test piece used in the rig wear test. FIG. 5 is an SEM image of the surface of the TiO ₂ film formed on the surface of the disk specimen of the AC4B material, which is a rotor material. The film thickness of the TiO ₂ film is (a) 5 μm, (b) 10 μm, and (c) 50 μm. It is. FIG. 6 is a graph showing the surface roughness of the surface of the TiO ₂ film formed on the disk test piece surface of the AC4B material, which is a rotor material. The film thickness of the TiO ₂ film is (a) 5 μm, (b). 10 μm and (c) 50 μm. FIG. 7 is a (a) front view and (b) side view of a pin test piece used in the rig wear test. 8A and 8B are diagrams for explaining a state in which the pin test piece is slid with respect to the disk test piece in the rig wear test, and FIG. 8B is formed in the R portion of the pin test piece after the wear test. It is a figure which shows a sliding scar wear width. FIG. 9 shows the disc wear reduction when sliding a pin test piece corresponding to (a) cast iron part and (b) chill part with respect to the disk test piece of the example and the comparative example in the rig wear test. FIG. FIG. 10 shows a pin sliding mark when a pin test piece corresponding to (a) cast iron portion and (b) chill portion is slid with respect to the disk test pieces of the examples and comparative examples in the rig wear test. It is a graph which shows a wear width.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or its application.

  FIG. 1 is a simplified view of a rotary piston engine according to the present embodiment. Each of the rotors (first sliding members) 4 that rotate the output shaft 3 on the trochoidal surface 2 of the rotor housing (third sliding member) 1. The top surface of the apex seal (second sliding member) 5 mounted on the top is slid. In this engine, fuel containing oil is sucked into the working chamber 7 together with air from the intake port 6, and the fuel moved in the direction of the arrow 8 while being compressed as the rotor 4 rotates is ignited by the spark plugs 9 </ b> A and 9 </ b> B. A series of steps of expanding and exhausting from the exhaust port 10 after the output shaft 3 is rotated by the pressure of the combustion gas is repeated.

  The rotor housing 1 is manufactured by casting, for example, a steel plate liner having a trochoidal surface 2 formed in an aluminum alloy. Since the trochoid surface 2 slides while the apex seal 5 is pressed as described above, high heat resistance, wear resistance, and low friction are required. For this reason, a Cr-containing plating film is formed on the trochoid surface 2.

  The rotor 4 is formed of a substantially triangular block body in which the central portion of each side bulges outward as viewed from the direction of the rotation axis, and has a base material made of an aluminum alloy.

  As the aluminum alloy material, for example, an AC2B material, an AC4B material, an AC4D material, an AC8A material, or the like specified in JIS standards, or an A390 material specified in AA (American Aluminum Association) standard can be used. Moreover, it is particularly preferable to use an AC4B material having excellent castability.

  A groove 41 for accommodating the apex seal 5 is provided at each of the approximately triangular tops of the rotor 4.

  FIG. 2A is an enlarged view of the top of the rotor. As shown in FIG. 2A, the apex seal 5 is housed in the groove 41 at the top of the rotor via a spring (not shown).

  Since the apex seal 5 is pressed against the trochoidal surface 2 of the rotor housing 1 by the spring, combustion gas pressure, and inertia force when the rotor rotates, the apex seal 5 slides up and down within the rotor groove 41. In addition, since the rotor 4 is pressed and tilted in the rotation direction, the edges of the rotor 4 and the apex seal 5 are strongly pressed. As a result, it is considered that the groove 41 at the top of the rotor is worn, for example, at positions A1 and A2 shown in FIG.

  Here, as described above, the Cr-containing plating film is formed on the trochoidal surface 2 of the rotor housing 1, and it is necessary to improve the wear resistance of the apex seal 5 that slides on the Cr-containing plating film. Accordingly, the vicinity of the apex (A3) of the apex seal 5 has a structure in which the cast iron structure is chilled. That is, as shown in FIG. 2B, the apex seal 5 includes a cast iron part 51 (base part) made of a cast iron structure and a chill part 52 formed by chilling the cast iron structure. Yes.

  Thereby, for example, the chill portion 52 of the apex seal 5 may slide on the edge of the rotor top portion shown in A2 of FIG. 2A, and the wear resistance of the groove portion 41 needs to be improved.

Therefore, the present invention is characterized in that a coating made of TiO ₂ is provided on the surface of the aluminum alloy base material of the rotor 4 and on the sliding contact surface with the apex seal 5.

The TiO ₂ film has a hardness of about Hv 500 or more, which is about the same as the hardness of the cast iron and cast iron that has been chilled. Therefore, the wear resistance of the sliding structure including the rotor groove 41 and the apex seal 5 can be improved by forming the TiO ₂ film on the sliding contact surface.

As shown in FIG. 3, the TiO ₂ film is formed on the surface of the sliding surface of the aluminum alloy substrate by plasma electrolytic deposition.

In the plasma electrolytic deposition method, as shown in FIG. 3, an aluminum alloy base material 14 connected to the anode 13 is immersed in an electrolyte solution 12 containing an electrolyte placed in an electrolytic cell 11. And a cathode 15 that is spaced apart from the aluminum alloy base material 14 and immersed in the electrolyte solution 12. The electrolyte 12 includes a titanium (IV) salt 16 that is a precursor of TiO ₂ as an electrolyte, specifically, a titanium halide such as TiCl ₄ or H ₂ TiF ₆ or a titanium oxyhalide such as TiOCl ₂ , or The electrolytic cell 11 contains titanium (IV) compounds such as titanyl sulfate and titanyl oxalate that generate titanyl (TiO ²⁺ ). In addition to the titanium (IV) salt and the like, the electrolytic solution 12 includes at least one other conductive salt as an electrolyte. Specifically, for example, nitrate, sulfate, perchlorate, and the like. Etc. Further, in addition to the electrolyte, the electrolytic solution 12 may include, for example, a stabilizer such as citrate, tartrate, and lactate, an accelerator such as hydroxylamine, and a buffer such as H ₃ PO ₄ . A voltage is applied between the electrodes 13 and 15 in the electrolytic solution 12 to generate an oxygen plasma 17, and a TiO ₂ layer 18 is electrolytically deposited on the surface of the aluminum alloy substrate 14 to form a TiO ₂ film. . In addition, the temperature of electrolyte solution becomes like this. Preferably it is 15 to 35 degreeC, More preferably, it is 20 to 30 degreeC, Most preferably, it is 23 to 27 degreeC.

The average voltage applied to both electrodes 13 and 15 is preferably 200 to 1000 V, particularly preferably 200 to 600 V, and it is preferable to use a direct current or a direct current pulse current. The average current density is preferably 0.02 to 100 mA / cm ² , particularly preferably 0.1 to 10 mA / cm ² . When a DC pulse current is used, it is preferable that the pulse width is 1 to 100 ms and the frequency is 10 to 1,000 Hz. The film thickness of the TiO ₂ film can be set to a desired film thickness by controlling these parameters depending on the average current density or the electrolytic treatment time.

Moreover, it is preferable to immerse only the rotor top part in the electrolytic solution as the aluminum alloy base material 14 and form a TiO ₂ film only on the sliding surface of the rotor groove 41 with the apex seal 5.

Therefore, according to the present invention, by forming a high hardness TiO ₂ film on the sliding contact surface of the rotor groove 41 with the apex seal 5, the sliding of the cast iron portion 51 and the chill portion 52 of the apex seal is prevented. Thus, the wear resistance of the rotor 4 can be improved, and a sliding structure with high durability and reliability can be obtained.

The film thickness of the TiO ₂ film is preferably 5 μm or more and 15 μm or less, and particularly preferably 5 μm or more and 10 μm or less. Further, the hardness of the film is preferably Hv500 or more and Hv800 or less, particularly preferably Hv600 or more and Hv800 or less. Then, in a preferred embodiment, the thickness of the TiO ₂ coating hardness of it and the film is 5μm or more 15μm or less is Hv500 or more Hv800 or less. In a particularly preferred embodiment, the film thickness is 5 μm or more and 10 μm or less, and the hardness of the film is Hv600 or more and Hv800 or less. As a result, while ensuring the excellent wear resistance of the rotor 4, it is possible to provide a sliding structure with a good balance between the two by suppressing the improvement of the partner's aggression and further improving the durability reliability of the sliding structure. be able to.

The porosity of the film is preferably 5.5% or more and 10% or less, more preferably 6.0% or more and 9.5% or less, and particularly preferably 6.4% or more and 9.2% or less. is there. As a result, the oil retaining property of the TiO ₂ film is kept good and the oil supply property to the sliding contact surface is increased, so that the wear resistance of the sliding structure is effectively improved.

  The surface roughness of the film is preferably Ra 0.1 μm or more and Ra 1.2 μm or less, more preferably Ra 0.4 μm or more and Ra 1.2 μm or less, and particularly preferably Ra 0.4 μm or more and Ra 1.0 μm or less. Thereby, the opponent aggression property to the apex seal 5 can be effectively suppressed while maintaining a good oil supply property.

  Next, specific examples will be described.

  After examining the specifications of the rotor material, a test piece was prototyped and a rig wear test simulating the sliding of the rotor and apex seal was performed to evaluate the durability reliability.

  Table 1 shows specific examples and comparative examples.

[Rotor material]
As shown in Table 1, the disk material of the disk test piece corresponding to the aluminum alloy rotor material was used in Examples 1 to 3 and Comparative Examples 1 and 3, and AC4B material having excellent castability was used. A high-Si alloy A390 material having excellent wear resistance was used. Table 2 shows the chemical composition and hardness of both aluminum alloys. The A390 material having a high Si content has a high hardness due to the large amount of Si crystallized material.

[Preparation of disc test piece]
Next, as shown in FIG. 4, a disk test piece 20 was prepared as a test piece for the rotor material.

  Both rotor materials described above were gravity cast using a sand-type disk test piece mold and then subjected to T6 heat treatment. The T6 heat treatment conditions were a solution treatment at 500 ° C. for 6 hours, followed by water cooling, and an aging treatment at 160 ° C. for 6 hours followed by air cooling. Thereafter, these were machined to produce a disk test piece 20 having a diameter 20a of 60 mm (a diameter 20b of both ends cut portion is 57 mm) and a thickness 20c of 5 mm.

[Surface treatment of disc specimen]
A metal oxide layer made of TiO ₂ was formed on the surface of the AC4B disc test piece 20 of Examples 1 to 3 by the plasma electrolytic deposition method shown in FIG.

The disk specimen was immersed in an electrolyte aqueous solution containing 20.0 g / L H ₂ TiF ₆ (60%) and 4.0 g / L H ₃ PO ₄ as the electrolyte. The pH was adjusted to 3.0 using aqueous ammonia. Electrolytic treatment was performed for a predetermined time with an electrolyte solution at 25 ° C. using a DC pulse current having an average voltage of 290 V, an average current density of 8.6 mA / cm ² , a pulse width of 25 ms, and a frequency of 30 Hz.

The film thickness of the TiO ₂ film was adjusted by the electrolytic treatment time. In Examples 1, 2, and 3, the electrolytic treatment times were 1.5 minutes, 3 minutes, and 15 minutes, respectively, and the film thicknesses of the TiO ₂ films were 5 μm, 10 μm, and 50 μm, respectively.

FIG. 5 is an SEM image of each TiO ₂ film surface. As shown in FIG. 5, the surface of the TiO ₂ film has pores, which enhances oil retention. FIG. 6 shows the surface roughness Ra of each TiO ₂ film surface.

Table 3 shows the porosity, hardness, and surface roughness of the TiO ₂ film surface.

  The porosity is obtained by determining the area ratio of the pores in the SEM image shown in FIG. 5 and is about 4 to 10% in Examples 1 to 3. Thereby, it turns out that a porosity is so high that a film thickness is thin. Further, the hardness is in the range of about Hv500 to Hv800. The surface roughness is about Ra 0.7 to Ra 1.6, and it can be seen that the surface roughness increases as the film thickness increases. The surface roughness can be reduced to about Ra0.4 by reducing the roughness of the substrate and reducing the film thickness.

In Comparative Example 3 shown in Table 1, the general anodization as a surface treatment _(Al 2 _{O 3} film formed, the film thickness 5 [mu] m) were. In this comparative example, the porosity could not be measured because the pores were too small.

  In Comparative Example 1 shown in Table 1, the same AC4B material as in Examples 1 to 3 was used as the rotor material, but no surface treatment was performed. Moreover, in the comparative example 2 shown in Table 1, the above-mentioned A390 material excellent in abrasion resistance was used as a rotor material, and the surface treatment was not performed similarly to the comparative example 1.

[Apex seal material]
As the apex seal material, a cast iron material composed of the components shown in Table 4 was used.

The as-cast structure of the apex seal is bainite, but as described above, the portion that slides with the rotor housing 1 is remelted with an electron beam to form a chill structure in which carbides are crystallized. Therefore, the apex seal is composed of a two-layered metal structure of a bainite cast iron part and a chill part of the chill structure. In addition, the hardness of a cast iron part and a chill part is Hv410 and Hv637, respectively.

[Production of pin specimen]
The shape of the pin test piece 21 used for the rig wear test is shown in FIG.

  As described above, since the structures of both the cast iron part 51 and the chill part 52 slide in the rotor groove part 41, the apex seal has R of two kinds of structures corresponding to the cast iron part and the chill part as the pin test piece 21. A pin test piece 21 having a portion 22 was produced.

  Specifically, a pin test piece shown in FIG. 7 was collected from the cast iron material described above. The pin test piece 21 corresponding to the cast iron part is used for the rig wear test as it is after sampling, and the pin test piece 21 corresponding to the chill part is remelted by electron beam after sampling to crystallize the carbide. The pin test piece 21 was used as a chill structure.

[Rig wear test conditions]
The sliding characteristics were evaluated by a pin-on-disk type friction and wear tester (manufactured by Takachiho Seiki Co., Ltd., dual micro tester μ-100N). As shown in FIG. 8, the R portion 22 of the pin test piece 21 as the apex seal material was pressed against the disk test piece 20 as the rotor material and slid back and forth.

  The test conditions were a test load of 85 N, a test temperature of 150 ° C., a stroke of 40 mm, a lubricating oil amount of 10 mL / min, an oil temperature of 90 ° C., a frequency of 2.5 Hz, and a test time of 60 minutes. As the lubricating oil, additive-free turbine oil # 32 (manufactured by JX Nippon Mining & Energy Corporation), which is inferior in lubricity compared to normal engine oil, was used.

  The amount of wear of the rotor material was evaluated by measuring the weight reduction amount (disc wear reduction (mg)) of the disc specimen 20 before and after the test. In addition, the rotor material was evaluated by measuring the width 23 of the sliding trace of the R portion 22 of the pin test piece 21 (pin sliding trace wear width (mm)) as the opponent of the rotor material.

[Rig wear test results]
Table 5, FIG. 9 and FIG. 10 show the test results of the rig wear test.

<Abrasion resistance of rotor material>
As shown in Table 5 and FIG. 9A, the disk wear reduction with respect to sliding of the pin test piece 21 corresponding to the cast iron portion 51 of the apex seal 5 indicates the wear resistance of the rotor material with respect to the cast iron portion 51. .

  The disk wear loss was 8.40 mg for the AC4B material not subjected to the surface treatment of Comparative Example 1 and 3.95 mg for the A390 material having higher wear resistance than the AC4B material of Comparative Example 2 with no surface treatment. .

On the other hand, in the AC4B material on which the TiO ₂ film of Examples 1 to 3 was formed, the disk wear loss was 0.15 to 0.34 mg, which was superior to the A390 material of Comparative Example 2 in all film thicknesses (5 to 50 μm). It showed high wear resistance. As a result, it was found that the wear resistance of the rotor material was greatly improved in the case where the TiO ₂ film was formed on the surface of the AC4B material as compared with the AC4B material and A390 material without surface treatment of Comparative Examples 1 and ₂ . .

It was also found that the thinner the TiO ₂ film, the smaller the disc wear loss and the better the wear resistance of the rotor material. This is presumably because the lower the film thickness, the higher the porosity and the higher the oil retention.

Further, the AC4B material formed with the Al ₂ O ₃ film of Comparative Example 3 has a weight loss of 2.9 mg, which is superior to that of the A390 material of Comparative Example 2, but the wear resistance of the TiO ₂ film. It was found that it was not possible. Although the Al ₂ O ₃ film has a lower hardness than the TiO ₂ film and has fine pores, the TiO ₂ film in which relatively large pores are dispersed may have higher oil retention. Conceivable.

  As shown in Table 5 and FIG. 9B, the disk wear loss due to sliding of the pin test piece 21 corresponding to the chill portion 52 of the apex seal 5 indicates the wear resistance of the rotor material against the chill portion 52. .

  The disc wear loss was 4.80 mg for the AC4B material without surface treatment of Comparative Example 1 and 1.05 mg for the A390 material of Comparative Example 2.

On the other hand, the disk wear loss of the AC4B material on which the TiO ₂ film of Examples 1 to 3 is formed is 0.9 to 1.25 mg, and the thin film (5 μm) and the intermediate film (10 μm) of Examples 1 and 2 are compared. The wear resistance was superior to that of the A390 material of Example 2.

Further, as in the case of the cast iron part, it has been found that the thinner the TiO ₂ film is, the smaller the disc wear loss is and the more the wear resistance of the rotor material is improved.

The disk wear loss of _Al 2 _{O 3} film of Comparative Example 3 is 2.40Mg, resulted in wear resistance inferior A390 material of Comparative Example 2.

From the above, the rotor 4 of the AC4B material on which the TiO ₂ film is formed exhibits higher wear resistance than both the A390 material and the Al ₂ O ₃ film with respect to both the cast iron part 51 and the chill part 52 of the apex seal 5. I found out.

[On the opponent attack of the rotor material]
As described above, the wear resistance of the rotor material can be effectively improved by forming the TiO ₂ film on the surface of the rotor material. However, since the hardness of the rotor 4 is increased by this, the attacking ability of the opponent is enhanced, and the apex seal 5 that is the counterpart material may be worn. Therefore, in Examples 1 to 3 and Comparative Examples 1 to 3 described above, the opponent attack of the rotor material was evaluated. That is, the aggression of the rotor material was evaluated based on the sliding mark wear width of the pin test piece which is the counterpart material of the disk test piece. Table 5 and FIG. 10 show the results of the rig wear test.

As shown in Table 5 and FIG. 10 (a), the cast iron part for the AC4B material without surface treatment of Comparative Example 1, the A390 material of Comparative Example 2, and the AC4B material with the Al ₂ O ₃ film of Comparative Example 3 formed. The sliding scar wear widths of the pin test pieces were 0.39 mm, 0.75 mm, and 0.39 mm, respectively.

On the other hand, the sliding trace wear width of the pin test piece of the cast iron part for the AC4B material on which the TiO ₂ film shown in Examples 1 to 3 is formed is 0.34 to 0.60 mm, and all film thicknesses ( 5 to 50 μm), and the opponent aggression was smaller than the A390 material of Comparative Example 2. However, compared to Comparative Examples 1 and 3, Example 1 has a smaller opponent aggression, but Examples 2 and 3 have a greater opponent aggression. This is thought to be due to the high hardness of the AC4B material on which the TiO ₂ film is formed.

However, in Comparative Examples 1 and 3, since the wear resistance of the rotor material is greatly inferior to that of Examples 1 to 3, considering the balance between wear resistance and opponent attack, the TiO of Examples 1 to 3 It can be said that the AC4B material having _two coatings is excellent.

Note that the thinner the TiO ₂ film is, the smaller the pin sliding scar wear width is. The thinner the TiO ₂ film is, the smaller the surface roughness is, so the grinding action on the mating material is small. It is thought that it was because of.

Moreover, as shown in Table 5 and FIG. 10 (b), the AC4B material without surface treatment of Comparative Example 1, the A390 material of Comparative Example 2, and the AC4B material with the Al ₂ O ₃ coating film of Comparative Example 3 formed thereon, The sliding mark wear widths of the chilled pin test pieces were 0.18 mm, 0.50 mm, and 0.18 mm, respectively.

On the other hand, the sliding mark wear width of the pin test piece of the chill portion with respect to the AC4B material on which the TiO ₂ film shown in Examples 1 to 3 is formed is 0.34 to 0.44 mm, which is the same as the cast iron portion described above. Moreover, the opponent aggression is smaller than the A390 material of Comparative Example 2. However, as compared with Comparative Examples 1 and 3, the results of the opponent attack were large in all of Examples 1 to 3.

However, as in the case of the cast iron part, in Comparative Examples 1 and 3, since the wear resistance of the rotor material is greatly inferior to that of Examples 1 to 3, the balance between wear resistance and opponent attack is taken into consideration. It can be said that the AC4B material on which the TiO ₂ films of Examples 1 to 3 are formed is excellent.

From the above test results, the TiO ₂ film shows better opponent attack than the A390 material and the Al ₂ O ₃ film in both the chill part and the cast iron part, compared with a general Al ₂ O ₃ anodized film The opponent's aggression is somewhat inferior, but it can be seen that the balance between wear resistance and opponent's aggression is excellent.

In the first sliding member, the slidable contact surface with the second sliding member is formed with a high hardness TiO ₂ film so that both the base portion and the chill portion of the second sliding member slide. On the other hand, the wear resistance of the first sliding member can be improved, and a sliding structure with high durability and reliability can be obtained, which is extremely useful. Further, by adjusting the film thickness of the TiO ₂ film, the hardness of the film, the porosity and / or the surface roughness of the film surface can be controlled, so the wear resistance of the first sliding member is improved. In addition, since it is possible to obtain a sliding structure with higher durability and reliability by suppressing an increase in the attacking property of the first sliding member relative to the second sliding member, it is extremely useful.

1 Rotor housing (third sliding member)
4 Rotor (first sliding member)
41 Groove 5 Apex seal (second sliding member)
51 Cast iron part (base)
52 Chill part

Claims (6)

A sliding structure in which a first sliding member having a base material made of an aluminum alloy and a second sliding member made of cast iron sliding with respect to the first sliding member are combined,
The first sliding member has a coating made of TiO ₂ on the sliding contact surface with the second sliding member on the surface of the base material,
The second sliding member includes a base made of a cast iron structure and a chill part formed by chilling the cast iron structure ,
The sliding structure, wherein a porosity of the film is 5.5% or more and 10% or less . A sliding structure in which a first sliding member having a base material made of an aluminum alloy and a second sliding member made of cast iron sliding with respect to the first sliding member are combined,
The first sliding member has a coating made of TiO ₂ on the sliding contact surface with the second sliding member on the surface of the base material ,
The second sliding member includes a base made of a cast iron structure and a chill part formed by chilling the cast iron structure,
The sliding structure characterized in that the surface roughness of the coating is Ra 0.4 µm or more and Ra 1.2 µm or less . In claim 1 or claim 2 ,
The film thickness is 5 μm or more and 15 μm or less,
A sliding structure characterized in that the film has a hardness of Hv500 or more and Hv800 or less. In any one of Claim 1 thru | or 3 ,
The chill portion of the second sliding member slides also on the third sliding member. In any one of Claim 1 thru | or 3 ,
The first sliding member is a rotor of a rotary piston engine having a groove at the top,
The sliding structure, wherein the second sliding member is an apex seal housed in the groove. In claim 4 ,
The first sliding member is a rotor of a rotary piston engine having a groove at the top,
The second sliding member is an apex seal housed in the groove;
The third sliding member is a rotor housing of the rotary piston engine.