JP3274286B2 - Cylinder liner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder liner used in an internal combustion engine, and more particularly to a cylinder liner having an inner peripheral surface coated with a thermal spray coating.

[0002]

2. Description of the Related Art In recent years, with an increase in the output of an engine, it has been strongly desired to improve the sliding characteristics of a cylinder liner, and it has been proposed to apply a thermal spray treatment to an inner peripheral surface.

However, when thermal spraying is performed on the inner peripheral surface of the cylinder liner, the adhesion of the thermal sprayed coating cannot withstand actual operation, and a phenomenon that the end of the thermal sprayed coating rises is observed. In particular, in the case of a material having poor adhesion, the film is lifted during polishing after thermal spraying.

[0004] Therefore, as a method of improving the adhesion of the thermal sprayed coating, conventionally, the thermal sprayed coating is melted by irradiating the entire surface of the coating with high-density energy such as laser after thermal spraying, and an alloy layer is formed at the boundary with the base material. Have been proposed.

[0005]

However, when high-density energy is applied to the sprayed coating, there is a problem that the sliding properties such as the seizure resistance of the coating are reduced. In addition, irradiating high-density energy such as a laser to the entire surface of the thermal spray coating increases costs.

An object of the present invention is to provide a cylinder liner in which the adhesion of a sprayed coating is improved without lowering the sliding characteristics of the sprayed coating.

[0007]

According to the constitution of the present invention, the inner peripheral surface is coated with a thermal spray coating, and the thermal spray coating is irradiated with high-density energy to perform a melting treatment. In a cylinder liner fused at a boundary portion, the fusion processing portion is formed only at a non-sliding end portion in a liner axial direction.

[0008]

In general, the stress that causes the thermal sprayed coating to peel is concentrated on the edge of the coating, so that the peeling occurs from the edge of the coating.
Therefore, if the adhesion at the end of the film is improved, the peel resistance of the entire film can be improved. The same applies to the spray coating on the inner circumference of the cylinder liner.

That is, the thermal spray coating in the cylinder liner of the present invention has a fusion-processed portion formed by fusing the thermal spray coating and the base material at the boundary between the ends in the axial direction of the liner. The adhesion is improved, and as a result, the peeling resistance of the entire sprayed coating formed on the inner peripheral surface can be improved.

[0010] Since the melted portion is formed only at the non-sliding end, the sliding characteristics of the sliding portion on the inner peripheral surface of the cylinder liner do not decrease, and good sliding characteristics are maintained. it can.

[0011]

FIG. 1 shows a cylinder liner according to an embodiment of the present invention. FIG. 1B shows that after the thermal spraying process is performed to form a thermal spray coating 2 on the inner peripheral surface of the cylinder liner 1, the thermal spraying is performed so as to be flush with the upper chamfered surface of the inner peripheral surface of the cylinder liner 1. The upper end of the coating 2 is polished.

Next, as shown in FIGS. 1 (a) and 1 (c), laser, electron beam, TIG arc, etc. are applied only to the non-sliding upper end of the thermal spray coating 2 in the liner axis direction. Is performed.

By this melting treatment, the sprayed coating is melted at the non-sliding upper end in the liner axis direction, and the liner base material 3 near the boundary with the sprayed coating 2 is also melted to form a melt-processed portion 4. Is done. Since the alloy layer is formed at the boundary between the thermal spray coating 2 and the base material 3, the fusion processing section 4 has high adhesion.

Since the thermal spray coating 2 on the inner peripheral sliding portion is not subjected to a melting treatment, sliding characteristics such as seizure resistance do not decrease, and good sliding characteristics can be maintained.

In the above description, an example was shown in which the melt processing portion 4 was formed only at the upper end portion where the heat load was high in the liner axis direction. A part may be formed.

Further, the melting processing portion 4 may be formed over the entire circumference in the liner circumferential direction, or may be formed partially in the circumferential direction.

The material of the cylinder liner 1 is steel, cast iron, an aluminum alloy or the like, and the material of the thermal spray coating 2 is as follows. The percentages shown below are weight ratios.

A composition in which 60 to 90% of chromium carbide is combined with one or two of the following 10 to 40%. -Ni-Cr alloy of 20-50% of Cr and remaining Ni. Cr 8-20%, B1-4%, Si 3-6%, C0.
Self-fluxing alloy of 3 to 2%, Fe 2 to 6%, Co 10% or less, and remaining Ni.

Cr 50-70%, C3-9%, residual Fe
High-carbon Fe-Cr alloy.

Cr 50-70%, C3-9%, residual Fe
The following one or two of the following high carbon Fe-Cr alloys
40% compounded. -Ni-Cr alloy of 20-50% of Cr and remaining Ni. Cr 8-20%, B1-4%, Si 3-6%, C0.
Self-fluxing alloy of 3 to 2%, Fe 2 to 6%, Co 10% or less, and the remaining Ni.

C 0.25 to 2.2%, Cr, Mo,
A steel material containing 13% or less of one or more of W and V.

FIG. 2 is a longitudinal sectional view showing a part of a piston portion of an engine equipped with the cylinder liner 1 of the present invention. A cylinder liner 1 is inserted and fixed in a bore of a cylinder block 5, and a piston 6 is inserted into the cylinder liner 1. A piston ring 8 is mounted in a piston ring groove 7 formed in the piston 6, and an outer peripheral surface of the piston ring 8 contacts an inner peripheral surface of the cylinder liner 1. The material of the piston ring 8 is made of martensitic stainless steel or the like, and the outer peripheral surface is coated with a hard Cr plating 9 or the like.

Hereinafter, in order to evaluate the cylinder liner 1, a peeling test and a seizure test were performed.

[Practical Test of Peeling Resistance] The cylinder liner 1 (material: JIS STKM13 carbon steel pipe for machine structure) was subjected to a peeling resistance test under the following operating conditions of a real machine. Actual operating conditions: φ86mm, in-line 4-cylinder, mounted on 2.2l diesel engine, full load durability test 300H
r.

The composition of the thermal spray coating, the thermal spray conditions, and the laser irradiation conditions in the melting treatment are shown in Tables 1, 2 and 3, respectively.

[0026]

(Note 1) SCM440: C 0.35%, S
i 0.2%, Mn 0.75%, Cr 1.1%, MoO.
2%, residual Fe (weight ratio).

(Note 2) SKD61: C 0.4%, Si
1.0%, Mn 0.3%, Cr 5.0%, Mo 1.3
%, V1.0%, residual Fe (weight ratio).

[0029]

[0030]

[0031]

As is clear from the peeling resistance test, the sprayed coating of the cylinder liner of the present embodiment in which only the upper non-sliding portion in the axial direction of the liner was melted was subjected to post-processing (polishing of the chamfered surface). And no honing finish on the inner peripheral surface) and no lift-off or peeling after operation of the actual machine. It can be seen that lifting and peeling occurred after the operation and peeling resistance was poor.

Next, a seizure resistance test was performed using a reciprocating abrasion tester.

The details of the reciprocating wear tester and the test conditions were as follows.

(1) Reciprocating wear tester FIG. 3 schematically shows a reciprocating wear tester. In FIG.
Reference numeral 10 denotes a plate-shaped test piece, which is mounted and fixed on a test table 11.
The tip of the pin-shaped test piece 12 is pressed against the upper surface of the test piece 10 by the hydraulic unit 13. In this state, test table 1
The wear test is performed by reciprocating 1 in a horizontal plane by the crank mechanism 14. Reference numeral 15 denotes a hydraulic load indicator, 16 denotes a load cell for detecting a frictional force, and 17 denotes a recorder for recording the detected frictional force.

(2) Sliding mating material (pin-shaped test piece 12) The material is carbon tool steel (JIS SK5) and the tip has a diameter of 18
After the spherical surface was machined to a thickness of 0.5 mm, hard Cr plating was performed, followed by polishing.

(3) Test piece (plate-like test piece 10) Material is carbon steel (JIS S45C), dimensions are 17 × 14
After forming thermal spray coatings of various compositions on one surface (sliding surface) at × 70 (mm), the surface was polished.

(4) Test Conditions For the above test pieces, a burn-in test is performed under the following conditions for the laser-sprayed coating and the laser-split-free coating. Burn-in test conditions: Load: Initially 10 kg, stepped up at 2 kg / min. Speed: 100 cpm Lubrication: Lubricating oil with viscosity equivalent to light oil 25 μl

Table 5, Table 2, and Table 3 show the composition of the thermal spray coating, the thermal spray conditions, and the laser irradiation conditions in the melting process, respectively.

[0040]

As is clear from the above seizure test, it is understood that the one coated with the sprayed coating has better seizure resistance than the cast iron material equivalent to FC25 as a comparative example. In addition, when the thermal spray coating was applied, it was found that those not subjected to the laser melting treatment had better seizure resistance than those subjected to the laser melting treatment.

From the peeling resistance test and the seizure resistance test described above, the cylinder liner of the present invention has good adhesion of the thermal spray coating 2 coated on the inner peripheral surface, Since the thermal spray coating 2 is not subjected to a melting treatment, sliding characteristics such as seizure resistance are excellent.

[0043]

As described above, according to the inner peripheral spray cylinder liner of the present invention, the sliding characteristics are good and the adhesion of the spray coating is good.

[Brief description of the drawings]

1A and 1B show a cylinder liner according to an embodiment of the present invention, wherein FIG. 1A is a longitudinal sectional view of the cylinder liner, FIG. It is a principal part expanded longitudinal cross-sectional view which shows.

FIG. 2 is a longitudinal sectional view showing a part of a piston portion of an engine equipped with the cylinder liner of the present invention.

FIG. 3 is a view schematically showing a reciprocating motion wear tester.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder liner 2 Thermal spray coating 3 Liner base material 4 Melt processing part 5 Cylinder block 6 Piston 7 Piston ring groove 8 Piston ring 9 Hard Cr plating 10, 12 Test piece 11 Test stand 13 Hydraulic unit 14 Crank mechanism 15 Hydraulic load indicator 16 Load cell 17 Recorder

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-79783 (JP, A) JP-A-62-121847 (JP, A) JP-A-1-242786 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) F16J 10/04 F02F 1/00 C23C 4/18

Claims (3)

(57) [Claims] 1. A cylinder liner in which an inner peripheral surface is coated with a thermal spray coating, the thermal spray coating is irradiated with high-density energy to perform a melting treatment, and the thermal spray coating and the base material are fused at a boundary portion thereof. A cylinder liner, wherein the melting portion is formed only at a non-sliding end in a liner axial direction. 2. The cylinder liner according to claim 1, wherein the melting processing portion is formed only at a non-sliding end portion on an upper end side in a liner axial direction. 3. The cylinder liner according to claim 1, wherein the fusion processing portion is formed only at a non-sliding end between an upper end side and a lower end side in the liner axial direction.