JPH0551784B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an improvement in the combination structure of an engine cylinder and a piston ring that slides on the inner wall surface of the cylinder. (Prior art) Conventionally, the wear resistance of this type of piston ring,
In order to improve scuff resistance (seize resistance),
It is well known that the sliding contact surface of the piston ring that slides on the cylinder inner wall surface is subjected to chrome plating treatment, or surface treatment is performed using molybdenum spraying as disclosed in, for example, Japanese Patent Laid-Open No. 52-102916. It is being However, even if such conventional technology is applied to high-output engines, the surface pressure between the piston rings and the inner wall of the cylinder in high-output engines is extremely high.
It becomes difficult to fully satisfy the high degree of wear resistance and scuff resistance required by the high-output engine,
There was a problem that the engine performance could not be maintained stably. That is, when chrome plating is applied, the wear of the inner wall surface of the cylinder on which the piston ring slides increases, and the scuff limit value decreases. Further, when a molybdenum thermal spraying treatment is performed, the amount of wear of the thermal sprayed layer itself increases and the scuff limit value also decreases. (Object of the Invention) The present invention has been made in view of the above points, and its object is to specify the material and hardness of the inner wall of the cylinder of the engine, and then apply a predetermined ratio of CrO2 to the sliding surface of the piston ring. (chromium oxide),
The purpose of this invention is to further improve the wear resistance and scuff resistance of piston rings and cylinders in engines by forming a sprayed amount having a composition of TiO ₂ (titanium dioxide) and SiO ₂ (silicon dioxide). (Structure of the Invention) In order to achieve the above object, the solution of the present invention is to construct the cylinder of the engine described above from an alloy cast iron material having a hardness of 170 to 270 Hv, and to apply 88% CrO to the sliding surface of the piston cylinder. ~95% by weight, 3% _SiO2
A composite sprayed layer having a composition of ~7% by weight and _TiO2 of 2~5% by weight is provided. As a result, in the composite thermal sprayed layer, the wear resistance of the thermal sprayed layer itself is increased by the CrO component, which is the base component, and this CrO component has self-lubricating properties.
By adding 2 to 5% by weight of TiO ₂ , the hardness of the sprayed layer is lowered and the scuff resistance against the cylinder inner wall surface is increased, and furthermore, the addition of the TiO ₂ component mentioned above improves the overall wear resistance of the sprayed layer. The decrease in hardness is counteracted by adding 3-7% by weight of high hardness _SiO2 . On the other hand, the cylinder is made of alloyed cast iron material with a hardness of Hv 170 to 270 in order to have good compatibility with this composite sprayed layer and improve its own wear resistance. In that case, TiO ₂ in the sprayed layer
If the addition ratio of the ingredients is less than 2% by weight, no improvement in scuff resistance can be expected, and if it exceeds 5% by weight, the hardness of the sprayed layer will decrease and the wear resistance of the piston link will be insufficient. Set to a range of %. In addition, if the composition ratio of the SiO ₂ component is less than 3% by weight, the wear resistance of the piston ring will be insufficient due to a decrease in hardness, and if it exceeds 7% by weight, the hardness will become too hard and cause a large amount of wear on the cylinder inner wall.
It is set within a range of 7% by weight. Therefore, the composition ratio of the remaining CrO component is set at 88 to 95% by weight. On the other hand, if the hardness of the inner wall of the cylinder made of alloy cast iron is less than Hv170, the hardness will be insufficient and the amount of wear will increase significantly due to sliding contact with the thermal sprayed layer of the piston ring. Since the amount of wear of the sprayed layer increases, it is therefore set in the range of Hv170 to 270. It is also possible to thermally spray a mixed powder of CrO and _SiO2 , but if this technology is applied directly to engine piston rings, the wear resistance of the piston rings will improve, but the hardness of the thermally sprayed layer will be high. Therefore, the amount of wear resistance on the cylinder inner wall surface increases significantly, and no practical advantage can be obtained. In contrast, in the configuration of the present invention, a specific component called TiO ₂ is added to the sprayed layer in a predetermined ratio, and the material and hardness of the cylinder material as a mating material for the piston ring are also specified. Therefore, the piston ring's wear resistance and scuff resistance are improved without abrasion of the cylinder inner wall by the piston ring's thermally sprayed layer. (Effects of the Invention) Therefore, according to the present invention, the engine cylinder is made of an alloy cast iron material having a hardness of 170 to 270 Hv, and the sliding surface of the piston ring that comes into sliding contact with the inner wall of the cylinder contains 88% CrO. ~95 wt%, TiO2 ~ ₂
5% by weight and SiO ₂ by 3% to 7% by weight, this material further improves the wear resistance and scuffing resistance of the piston ring while suppressing wear on the cylinder inner wall surface. This makes it possible to maintain stable performance even when applied to high-output engines. (Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. In FIG. 1, reference numeral 1 denotes a cylinder of an engine according to an embodiment of the present invention, and the cylinder 1 is made of an alloy cast iron material such as flake graphite cast iron, and its hardness is in the range of Hv170 to Hv270 on the Vickers hardness. It is set. Reference numeral 2 denotes a piston that reciprocates within the cylinder 1. A ring groove 3 is formed on the outer peripheral surface of the piston 2, and a ring groove 3 is formed in the link groove 3. A piston ring 4 such as a top ring is attached. In the piston ring 4, a groove 5 is formed by recessing a substantially central portion of the ring 4 in the width direction along the circumferential direction on the sliding contact portion 4a, that is, on the outer circumferential surface that slides in contact with the cylinder inner wall surface 1a. 5, a composite sprayed layer 6 having a composition of 88 to 95% by weight of CrO, 3 to 7% by weight of SiO ₂ and 2 to 5% by weight of TiO ₂ is attached to the piston ring 4.
It is filled and formed so as to be substantially flush with the outer peripheral surface. Furthermore, on the surface of the piston ring 4, on the surface of the thermal sprayed layer 6 except for the middle part in the width direction,
A Ni--F composite plating layer 7 containing 15 to 30% by volume of F (fluororesin) particles is formed, and the thickness of the plating layer 7 is set in a range of 10 to 20 microns. Here, the alloy cast iron constituting the cylinder 1 contains C, Si, Mn, P, S, and Cr in its Fe components.
Each component such as Cu, Mo, and Sn is added depending on the type, and the composition ratio of each component is as follows.
C 3.00 to 3.70% by weight, Si 1.30 to 2.30% by weight,
Mn is set to 0.50 to 0.90 weight%, P and S are both set to 0.10 weight% or less, Cr is set to 0.05 to 0.5 weight%, Cu is set to 0.5 to 1.0 weight%, Mo is set to 1.0 weight% or less, and Sn is set to 0.10 weight% or less. This is what has been done. In other words, when the composition ratio of the C component is less than 3.00% by weight, the amount of carbides decreases, resulting in a decrease in hardness and coarsening of the pearlite structure, resulting in a decrease in mechanical strength, while when it exceeds 3.70% by weight, graphite increases and the strength decreases, so it is set in the range of 3.00 to 3.70% by weight. If the composition ratio of the Si component is less than 1.30% by weight, the amount of graphite produced will decrease, and if it exceeds 2.30% by weight, the graphite ratio will increase and the strength will decrease.
It is set in the range of 1.30 to 2.30% by weight. Mn is added for desulfurization and stabilization of pearlite structure, and is set in the range of 0.50 to 0.90% by weight. Further, the P and S components are suppressed to a composition ratio of 0.10% by weight or less as usual. The Cr component improves mechanical strength and wear resistance by making the base entirely pearlite structure. If the crude composition ratio is less than 0.05% by weight, the amount of carbide decreases and the hardness decreases, and it becomes 0.5% by weight. If it exceeds the amount, the amount of carbide increases and machinability decreases, so it is set in the range of 0.05 to 0.5% by weight. The Cu component densifies the pearlite structure and improves mechanical properties.
It is set in the range of ~1.0% by weight. The Mo component improves the high-temperature hardness and fatigue strength of the matrix, and its composition ratio is set to 1.0% by weight or less since graphitization will be inhibited if it exceeds 1.0% by weight. Sn improves the high temperature hardness of the base, and if its composition ratio exceeds 1.0% by weight, it will make the base brittle.
Set at 1.0% by weight or less. Further, the layer thickness of the composite sprayed layer 6 formed on the sliding contact portion 4a of the piston ring 4 is set to 150μ or less in order to improve the adhesion between the sprayed layer 6 and the piston ring 4 base material and prevent peeling. is preferable. Furthermore, if the content ratio of F particles in the Ni-F composite plating layer 7 formed on the surface of the piston ring 4 is less than 15% by volume, the self-lubricating properties of the fluororesin will decrease, resulting in an initial break-in. If the amount exceeds 30% by volume, the adhesion of the composite plating layer 7 to the base material of the piston ring 4 decreases, making it easy to peel off, so the amount is set in the range of 15 to 30% by volume. Furthermore, if the particle size of the fluororesin particles is less than 0.3μ, it is difficult to manufacture, and if it exceeds 3μ, the adhesion with the Ni component will decrease, so it is preferable to set the particle size in the range of 0.3 to 3μ. Furthermore, the layer thickness of the Ni-F composite plating layer 7 is
If it is less than 10μ, the initial conformability will not be improved enough, and if it exceeds 20μ, the abutment of the piston ring 4 will widen as the plating layer 7 wears, leading to an increase in probe gas. Set to range. Therefore, in the above embodiment, the sliding contact portion 4a of the piston ring 4 with the cylinder inner wall surface 1a
A composite sprayed layer 6 consisting of 88 to 95% by weight of CrO, 3 to 7% by weight of SiO ₂ and 2 to 5% by weight of TiO ₂ is formed, and the composite sprayed layer 6 contains a CrO component and a SiO ₂ component. Since the piston ring 4 organically has wear resistance and scuff resistance due to TiO ₂ , the wear resistance and scuff resistance of the piston ring 4 can be improved.
Moreover, since the cylinder 1, which is the mating material with which the piston ring 4 comes into sliding contact, is made of an alloy cast iron material with a hardness of Hv170 to Hv270, this cylinder 1
By setting the hardness, the cylinder inner wall surface 1a becomes difficult to wear even if it comes into sliding contact with the composite thermally sprayed layer 6 of the piston ring 4, thereby improving the wear resistance of both the piston ring 4 and the cylinder 1, and improving the wear resistance of both the piston ring 4 and the cylinder 1. It is possible to improve the scuff resistance between the two. In that case, although the composite thermal sprayed layer 6 formed on the piston ring 4 has good wear resistance and scuff resistance, since it is a type of ceramic material, it has a high coefficient of friction, which can cause engine output loss and initial run-in. This may lead to a decrease in However, in this embodiment, the Ni-F composite plating layer 7 is partially formed on the sliding contact portion 4a of the piston ring 4, and this Ni
-The F composite plating layer 7 has low hardness and self-lubricating properties due to the F component, and maintains a low coefficient of friction even at high temperatures. Furthermore, it has gasoline resistance, oil resistance, and heat resistance, so it can be used during the initial operation of the engine. At times, when the piston ring 4 comes into sliding contact with the cylinder inner wall surface 1a as the piston 2 reciprocates within the cylinder 1, the surface between the piston ring 4 and the cylinder inner wall surface 1a as shown in FIG. The above Ni-
The F composite plating layer 7 becomes abrasion powder and transfers onto the surface of the composite sprayed layer 6, and finally, as shown in enlarged detail in FIG. It also metastasizes within the parts 6a, 6a, . Due to this transfer of the plating layer 7 onto the thermal sprayed layer 6, the thermal sprayed layer 6 comes to indirectly come into sliding contact with the cylinder inner wall surface 1a via the plating layer 7, and therefore the piston ring 4 due to the composite thermal sprayed layer 6 By reducing the frictional resistance between the cylinder inner wall surface 1a and the cylinder inner wall surface 1a, it is possible to improve the initial adaptability of the engine. In order to improve the adhesion of the composite sprayed layer 6 to the base material of the piston ring 4, the base material of the piston ring 4 may be sprayed with an MO-based self-fluxing alloy as a base treatment. Further, in order to improve the thermal shock resistance of the composite sprayed layer 6, Ti (titanium), Y (yttrium), etc. may be added to the sprayed powder. Further, in the above embodiment, the Ni-F composite plating layer 7 was formed on the piston ring 4 side, but instead, Ni-F composite plating may be applied to the cylinder inner wall surface 1a. In that case, the content ratio of F particles in the plating layer should not be the same as in the above example.
It is necessary to change the plating layer to a range of 15 to 40% by volume, and to set the thickness of the plating layer to a range of 15 to 20 μm as in the above embodiment. Furthermore, in the above embodiment, the Ni-F composite plating layer 7 was formed on the piston ring 4 in order to reduce frictional resistance and improve initial conformability. Alternatively, polyimide or polyamide resin may be baked and coated. Next, specific examples will be described. FIG. 4 shows a wear resistance evaluation test device for testing the wear resistance of the prepared sample material.
a cylinder material fixing base 52 on which the cylinder material fixing base 52 places and fixes the cylinder member 1 with its inner wall side facing upward; and a rod support base 54 that slidably supports the rod 53 extending in the horizontal direction.
is connected to one end of the rod 53, and the sliding surface of the piston ring material 55 is connected to the cylinder material 51.
The piston ring material mounting portion 56 is provided with a piston ring material mounting portion 56 that is supported so as to be in contact with the upper surface, and a drive motor 58 that is connected to the other end of the rod 53 via a crank mechanism 57 and that slides the rod 53. Applying a predetermined load _P1 to the mounting portion 56, the piston ring material 55 is brought into pressure contact with the cylinder material 51,
In this state, the drive motor 58 is operated to cause the piston ring material 55 to reciprocate and slide on the cylinder material 51, thereby causing the cylinder material 51 and the piston ring material 55 to wear, and measuring the wear layers thereof. And test the above load P ₁ to 5
~15Kg, the reciprocating width of the piston ring material 55 is 10
The test was carried out under dry conditions in the atmosphere, with the reciprocating speed set at 700 mm, the reciprocating speed at 20,000 times/min, and the reciprocating distance at 20,000 times/min. Further, FIG. 5 shows a scuffing resistance evaluation test device for testing the scuffing resistance of sample materials.
a rotary table 59 that is placed and fixed so that its inner wall side is the upper surface and rotates;
a piston ring material mounting portion 60 that is provided above the outer peripheral portion of the piston ring material 9 so as to be movable by a predetermined distance in the circumferential direction, and supports the piston ring material 55 so that its sliding surface contacts the upper surface of the cylinder material 51; It is equipped with a friction force meter 61 that measures the amount of movement of the piston ring material mounting portion 60, and an oil pump 62 that applies lubricating oil to the cylinder material 51 on the rotary table 59,
While supplying lubricating oil from the oil pump 62 onto the rotary table 59, the rotary table 59 is rotated to bring the piston ring material 55 and the cylinder material 51 into sliding contact, and in this state, the piston ring material mounting portion 60
Gradually increase the load P ₂ applied to the piston ring material 55 to increase the surface pressure between the piston ring material 55 and the cylinder material 51. It measures the value. Then, the test was carried out using the above load P ₂ from 0 to 80 kg, cylinder material 51
The test was carried out under the conditions that the circumferential speed of the abutting part such as the piston ring material 55 was set to 7.3 m/s, and the lubricating oil was set to machine oil. Using the above two types of test equipment, nine tests were conducted on each sample of cylinder material and piston ring material. That is, first, C is 3.40% by weight, Si is 2.00% by weight, Mn is 0.70% by weight, and P is
0.05% by weight, S 0.05% by weight, Cr 0.2% by weight,
The cylinder material is made of alloyed cast iron having a composition (basic composition) of 0.15% by weight of Cu, 0.07% by weight of Sn, and the balance of Fe, while on the surface of the base material made of high phosphorus cast iron,
Using a piston ring material formed by forming a composite sprayed layer with a thickness of 150μ or less, which has a composition in which the proportions of SiO ₂ 5% by weight, TiO ₂ and CrO are relatively changed, the scuff limit value and piston ring material When the amount of wear was measured, the measurement results were as shown in FIG. As is clear from Fig. 6, if TiO ₂ is less than 2% by weight in the composition of the composite thermal sprayed layer formed on the sliding surface of the piston ring material, the scuff limit value will exceed the limit line (32Kg/mm ² -m 2 ). /s), and if it exceeds 5% by weight, the amount of wear of the piston ring material will exceed the limit line (0.45mg),
Therefore, it can be seen that when the composition ratio of TiO ₂ is in the range of 2 to 5% by weight, the scuff resistance and the wear resistance of the piston ring material are improved. In addition, using the cylinder material with the basic composition described above,
On the other hand, a piston is made by forming a composite sprayed layer with a thickness of 150μ or less, which has a composition of 3% by weight TiO ₂ and a relatively changed ratio of SiO ₂ and CrO, on the surface of a high phosphorus cast iron base material. When the wear layers of the cylinder material and piston ring material were measured using the ring material, the measurement results were as shown in FIG. 7. As is clear from Fig. 7, in the composition of the composite sprayed layer, if SiO ₂ is less than 3% by weight, the wear amount of the piston ring material exceeds the limit line, and the amount of wear of the piston ring material exceeds the limit line.
If it exceeds the weight%, the wear amount of the cylinder material will exceed the limit line (20mg), therefore, if the composition ratio of SiO ₂ is in the range of 3 to 7% by weight, the wear resistance of the cylinder material and piston ring material will be improved. It can be seen that the performance improves. Furthermore, the composite sprayed layer formed on the sliding surface of the piston ring material is made of 92% by weight of CrO, 5% by weight of _SiO2 ,
The composition is 3% by weight of TiO ₂ and the layer thickness is
150μ or less, and the composition and hardness of the cylinder material were changed in four ways as shown in Table 1 below, and the wear amount of each cylinder material and piston ring material was measured, and the measurement results are shown in Figure 8. It became.

[Table] As is clear from Fig. 8, when the hardness of the alloy cast iron cylinder material is less than Hv170, the amount of wear on the cylinder material exceeds the limit line, and when it exceeds Hv270, the amount of wear on the piston ring material increases. The hardness of the cylinder material exceeds the limit line, so the hardness of the cylinder material is Hv170~
It can be seen that if the value is set within the range of 270, the wear resistance of both the cylinder material and the piston ring material will be improved. In addition, while using the cylinder material with the above-mentioned basic composition, a piston ring material is created by forming a composite sprayed layer on the sliding surface with a composition of 92% by weight of CrO, 5% by weight of SiO ₂ and 3% by weight of TiO ₂ . The amount of wear on the cylinder material was measured by changing the surface pressure between the cylinder material and the piston ring material (the load P ₁ applied to the piston ring material 55 in the wear resistance evaluation test device shown in Fig. 4). However, the results were as shown in Figure 9. As a comparative example, a piston ring material was used in which a Cr plating layer with a thickness of 150 μm was formed on the sliding surface. As is clear from FIG. 9, when the piston ring material plated with Cr is used, the cylinder material wears out significantly as the surface pressure increases, whereas when the piston ring material of the example of the present invention is used, The surface pressure is within the range used by high-output engines.
It can be seen that the amount of wear on the cylinder material is lower than the standard line even when the value increases to 0.4 to 0.5 Kg/ ^mm2 . In addition, while using the cylinder material having the above-mentioned basic composition, using a piston ring material having a composite sprayed layer or a Cr plating layer having various compositions as shown in Table 2 below on the sliding contact surface, the above-mentioned fourth Similar to the above test, the wear amount of the piston ring material was measured by changing the surface pressure between the cylinder material and the piston ring material, and the results were as shown in FIG. 10.

[Table] As ^is clear from Fig. 10, when the piston ring material of the present invention example (sample _No. It can be seen that the wear does not exceed the standard value. Therefore, from these test results, the piston ring material of the example of the present invention can be satisfactorily applied to high-output engines. In addition, while using the cylinder material with the above basic composition, we also measured the scuff limit value using the same piston ring material (see Table 2) as used in the test for the amount of wear of the piston ring material against the above surface pressure. The measurement results shown in Figure 11 were obtained. As is clear from FIG. 11, when the piston ring material according to the present invention (sample No. R ₁ ) is used, the scuff limit value rises above the limit line. Further, while using the cylinder material having the basic composition described above, using a piston ring material formed with the composite sprayed layer according to the present invention or various sprayed layers or plating layers as comparative examples on the sliding surface, When the amount of wear of the cylinder material and piston ring material was measured, the results were as shown in FIG. 12.
Further, the scathing limit value was measured using a sample having the same configuration as in this test, and the results were as shown in FIG. 13. As is clear from FIGS. 12 and 13, the piston ring material according to the present invention can improve both the wear resistance and scuff resistance of the cylinder material and piston ring material. Finally, while using the cylinder material with the above basic composition, a composite sprayed layer having a composition of 92% by weight of CrO, 5% by weight of SiO ₂ and 3% by weight of TiO ₂ is formed on the sliding surface, and On the surface, a Ni-F composite plating layer (the content of F particles is
Using a piston ring material with a layer thickness of 30% by volume and a layer thickness of 15μ, the piston ring material was brought into sliding contact with the cylinder material at a surface pressure of 0.4Kg/ ^mm2 , and the amount of wear on the cylinder material was measured against the friction distance. As a result, the results shown in FIG. 14 were obtained. As a comparative example, a piston ring material without the Ni-F composite plating layer was used. As is clear from FIG. 14, when the Ni-F composite plating layer is not formed on the piston ring material, the amount of wear of the cylinder material increases while the friction distance is relatively short, whereas the amount of wear on the cylinder material increases while the friction distance is relatively short. It can be seen that when this is formed, the plating layer wears smoothly, the initial conformability improves, and the amount of wear of the cylinder material decreases overall.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a cross-sectional view of the main part, FIG. 2 is a cross-sectional view of the main part showing the initial break-in state of the engine, and FIG. 3 is a cross-sectional view of the main part after the initial break-in is almost completed. An enlarged cross-sectional view of the main parts of a piston ring, Fig. 4 is a schematic explanatory diagram of the wear resistance evaluation test device, Fig. 5 is a schematic explanatory diagram of the scuff resistance evaluation test device, and Fig. 6 is a diagram showing the scuff resistance against the TiO ₂ composition ratio. An explanatory diagram showing changes in limit values and piston ring wear amount. Fig. 7 is an explanatory diagram showing changes in cylinder and piston ring wear amount with respect to the composition ratio of S ₁ O _2. Fig. 8 is an explanatory diagram showing changes in cylinder and piston ring wear amount with respect to cylinder hardness. Explanatory diagram showing changes in wear amount,
Fig. 9 is an explanatory diagram showing changes in cylinder wear amount with respect to surface pressure, Fig. 10 is an explanatory diagram showing changes in piston ring wear amount with respect to surface pressure, and Fig. 11 is an explanatory diagram showing changes in scuff limit value between the present invention example and comparative example. Fig. 12 is an explanatory drawing showing a comparison between the cylinder and piston ring wear amount between the inventive example and the comparative example, and Fig. 13 is an explanatory drawing showing the scuff limit value of the inventive example. Explanatory diagram showing comparison with other general examples, 1st
FIG. 4 is an explanatory diagram showing the change in the amount of cylinder wear depending on the presence or absence of the Ni-F composite plating layer. DESCRIPTION OF SYMBOLS 1... Cylinder, 1a... Inner wall surface, 2... Piston, 4... Piston ring, 4a... Sliding contact part, 6... Composite thermal spray layer, 7... Composite plating layer.

Claims (1)

[Claims] 1 A combination structure of an engine cylinder and a piston ring that is attached to the outer periphery of a piston that reciprocates within the cylinder and makes sliding contact with the inner wall surface of the cylinder, and the cylinder is made of alloy cast iron material having a hardness of Hv170 to 270. On the other hand, the sliding contact area of the piston ring contains 88 to 95% by weight of CrO and 3 to 3% by _weight of SiO2.
A combination structure of an engine cylinder and a piston ring, characterized in that a composite sprayed layer is provided with a composition of 7% by weight and 2 to 5% by weight of _TiO2 .