JP5678416B2 - Cylinder liner and cylinder block - Google Patents

Description

  The present invention relates to a cylinder liner and a cylinder block in which a cylinder bore for slidably receiving an engine piston is formed.

  Generally, an engine piston is accommodated in a cylinder bore formed in a cylinder block or a cylinder liner incorporated in the cylinder block.

  Conventionally, in a cylinder liner and a cylinder block, in order to prevent seizure (scuffing) between a piston and a cylinder bore, cross-hatch processing is performed on the inner peripheral surface of the cylinder bore (see, for example, Patent Document 1).

  For example, in the cross-hatch processing of the cylinder liner, as shown in FIG. 4, the inner peripheral surface 82 of the cylinder bore 81 is shaved with a cutter or the like to form a cross-hatch-like minute groove (streaks) 83. In the cylinder liner (block) that has been subjected to cross hatching, seizure (scuffing) with the piston is prevented by storing lubricating oil in the cross hatch portion.

JP 2009-78320 A

  However, since the inner peripheral surface of the cylinder bore is cut in the cross-hatch processing, as shown in FIG. 4B, burrs exist along the streaks and the cross-hatch is fluffy. This was a cause of increased sliding resistance.

  Thus, the cylinder liner (block) subjected to the cross hatching has a problem that the sliding resistance with the piston is large.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cylinder liner and a cylinder block that can solve the above-described problems and reduce the sliding resistance with a piston while preventing scuffing.

In order to achieve the above object, the present invention defines a cylinder bore that slidably accommodates a piston of an engine, and performs surface treatment to prevent seizure with the piston on the inner peripheral surface of the cylinder bore. In the cylinder liner formed of the boron cast iron or cast iron, the surface treatment is performed on the inner peripheral surface of the cylinder bore by using a fine particle shot material having a particle diameter of 5-20 μm made of molybdenum disulfide. Shot peening is performed so that only a part of molybdenum disulfide that collides with the surface is embedded in the inner peripheral surface of the cylinder bore, and dimples made of molybdenum disulfide are formed on the inner peripheral surface of the cylinder bore. A part of the molybdenum disulfide is embedded in the circumferential surface by 1-2 μm .

In order to achieve the above object, the present invention provides a cylinder bore for slidably receiving an engine piston formed of cast iron or chrome cast iron, and prevents seizure of the piston on the inner peripheral surface of the cylinder bore. In the cylinder block subjected to the surface treatment, the surface treatment collides with the inner peripheral surface of the cylinder bore and the inner peripheral surface of the cylinder bore using a fine particle shot material made of molybdenum disulfide having a particle diameter of 5 to 20 μm. Shot peening is performed so that only a part of molybdenum disulfide is embedded in the inner peripheral surface of the cylinder bore, dimples made of molybdenum disulfide are formed on the inner peripheral surface of the cylinder bore, and the inner peripheral surface of the cylinder bore is formed. A part of the molybdenum disulfide is embedded with 1-2 μm .

  Preferably, the fine particle shot material has a particle size of 5 to 20 μm.

  According to the present invention, the excellent effect of reducing the sliding resistance with the piston while preventing scuffing is exhibited.

FIG. 1 is a schematic structural diagram of a cylinder liner according to an embodiment of the present invention. FIG. 2 is a graph of the test result of the friction variation test. FIG. 3 is a schematic structural diagram of a cylinder block according to another embodiment. FIG. 4A is a schematic structural diagram of a conventional cylinder liner, and FIG. 4B is a partially enlarged photograph of a cross hatch portion.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(First embodiment)
The first embodiment is intended for a cylinder liner, and is applied to, for example, a diesel engine mounted on a vehicle.

  Based on FIG. 1, the schematic structure of the cylinder liner of this embodiment will be described.

  As shown in FIG. 1, a cylinder liner 1 defines a cylinder bore 5 in which a piston 3 of an engine 2 is slidably accommodated, and an inner peripheral surface (hereinafter referred to as a bore inner peripheral surface) 6 of the cylinder bore 5. Is subjected to a surface treatment for preventing seizure (scuffing) with the piston 3 (hereinafter referred to as “scuffing prevention surface treatment”).

The cylinder liner 1 of the present embodiment uses a fine particle shot material made of molybdenum disulfide (MoS ₂ ) as a scuff-preventing surface treatment instead of the conventional cross-hatch processing, so that the bore inner peripheral surface (sliding with the piston 3) Surface) 6 is shot peened and molybdenum disulfide is embedded in the bore inner peripheral surface 6.

That is, the cylinder liner 1 of the present embodiment is one in which cross hatching is abolished. At that time, a solid lubricant of molybdenum disulfide (MoS ₂ ) is embedded in the inner peripheral surface (bore inner peripheral surface 6) of the cylinder liner 1 by shot peening to prevent scuffing.

  More specifically, a liner accommodation hole 22 extending vertically is formed in the cylinder block 21 of the engine 2, and the cylinder liner 1 is inserted and fitted into the liner accommodation hole 22.

  The cylinder liner 1 has a substantially cylindrical shape extending vertically. The cylinder liner 1 is made of, for example, boron cast iron or cast iron and is formed by casting. The cylinder liner 1 is fitted into the cylinder block 21 by being fitted into the liner accommodation hole 22 and the flange 11 formed at the upper end portion of the cylinder liner 1 being brought into contact with the stepped portion 221 formed at the upper end of the liner accommodation hole 22. It is done.

  A cylinder bore 5 is defined on the inner periphery of the cylinder liner 1, and the piston 3 is disposed in the cylinder bore 5 so as to be able to reciprocate up and down.

  The piston 3 is connected to the crankshaft via a connecting rod (not shown). A plurality of ring grooves (a top ring groove 31, a second ring groove 32, and an oil ring groove 33 in order from the top in the example) are formed on the outer peripheral surface of the piston 3 at predetermined intervals in the vertical direction. Compression rings 34 and 35 for sealing combustion gas are fitted into the top ring groove 31 and the second ring groove 32, and an oil ring 36 for scraping off the lubricating oil is fitted into the oil ring groove 33. The oil ring groove 33 is connected to an oil hole (not shown) formed in the piston 3, and lubricating oil from the oil ring groove 33 is supplied between the piston 3 and the cylinder liner 1.

  The compression rings 34 and 35 and the oil ring 36 are in sliding contact with the bore inner peripheral surface 6 of the cylinder liner 1.

  Next, the scuff prevention surface treatment according to the present embodiment will be described.

  First, a nozzle for injecting the fine particle shot material is inserted into the cylinder liner 1, and the nozzle nozzle hole faces the bore inner peripheral surface 6. Compressed air and a fine particle shot material made of molybdenum disulfide are supplied to the nozzle, and the fine particle shot material is sprayed onto the bore inner peripheral surface 6 by the compressed air.

  Thereby, the fine particle shot material ejected from the nozzle collides with the bore inner peripheral surface 6, and dimples (dents) for holding lubricating oil are formed on the bore inner peripheral surface 6 by the collision. Further, a part of the fine particle shot material (molybdenum disulfide) colliding with the bore inner circumferential surface 6 is embedded in the bore inner circumferential surface 6 (surface) by about 1-2 μm.

  While spraying the fine particle shot material, the nozzle is moved to the entire circumference of the cylinder bore 5 and to the entire length of the cylinder bore 5 in the axial direction, so that the scuff-preventing surface treatment (shot) Peening and embedding molybdenum disulfide). This anti-scuffing surface treatment is performed for about 30 seconds to 5 minutes per cylinder liner 1.

  Here, the particle size of the fine particle shot material (molybdenum disulfide) is not less than 5 μm and less than 20 μm, more preferably about 10 μm. This is because when the particle diameter is less than 5 μm, dimples having a size (size and depth) sufficient to hold the lubricating oil on the bore inner peripheral surface 6 cannot be formed. When the particle size is 20 μm or more, the size of the dimples formed on the bore inner peripheral surface 6 becomes too large, the roughness of the bore inner peripheral surface 6 becomes rough, and the sliding resistance increases.

  The nozzle injection pressure (compressed air pressure) is 8-10 atm (810.6 k-1013.25 kPa).

  According to the cylinder liner 1 of the present embodiment, the lubricating oil is held by the dimples formed on the bore inner peripheral surface 6 during operation of the engine 2, and scuffing between the cylinder bore 5 and the piston 3 is prevented. Further, molybdenum disulfide embedded in the bore inner peripheral surface 6 acts as a solid lubricant, and sliding resistance between the cylinder bore 5 and the piston 3 is reduced.

  That is, in this embodiment, the cross hatching of the cylinder liner 1 can be abolished without generating scuffing, and the sliding resistance with the piston 3 can be reduced. As a result, the friction of the internal combustion engine (engine 2) can be reduced and fuel consumption can be improved.

  Next, a single product test result of the cylinder liner according to the present embodiment will be shown.

  FIG. 2 shows the results of measuring friction force fluctuations every 5 minutes (5 min), 2 hours (2 Hr), and 8 hours (8 Hr) for cylinder liners subjected to different scuffing prevention surface treatments.

In FIG. 2, MoS ₂ shot is an embodiment of the present invention, and molybdenum disulfide having a particle diameter of 10 μm is used as a fine particle shot material on a bore inner surface of a cylinder liner made of boron cast iron at an injection pressure of 8-10 atm. Shot peening was applied for 20 seconds.

  No treatment (FC) is a conventional example, and is a test result of a cylinder liner in which a bore inner peripheral surface is subjected to cross hatching.

The Sn shot is a test result of a cylinder liner in which Sn is used as a fine particle shot material and the other processes are the same as those of the MoS ₂ shot.

The micro dimple is a test result of a cylinder liner in which ceramic beads are used as a fine particle shot material and the other processes are the same as those of the MoS ₂ shot. In the micro dimple, only the dimple is formed on the inner peripheral surface of the bore, and the ceramic beads are not embedded.

  The MD + Sn shot is a test result of a cylinder liner in which a microdimple cylinder liner is further processed in the same manner as the Sn shot.

The MD + MoS ₂ shot is a test result of a cylinder liner in which a microdimple cylinder liner is further processed in the same manner as the MoS ₂ shot.

  The test was conducted by dropping only one drop of lubricating oil between the piston and cylinder liner, and then sliding (reciprocating) the piston and cylinder liner without refueling. Changes were measured. From the measured value, a value obtained by dividing the maximum frictional force Max by the minimum frictional force Min was obtained and evaluated as a frictional force variation.

As shown in FIG. 2, in the example (MoS ₂ shot), the friction force fluctuations at 5 minutes, 2 hours, and 8 hours are generally low, and the friction force fluctuations tend to decrease with time. Compared to the examples, the sliding performance was good (low friction). Also, there was no aspect of scuffing.

On the other hand, the Sn shot, micro dimple, MD + Sn shot, and MD + MoS ₂ shot did not have any streak processing, but only a frictional force change almost equivalent to that of the conventional example was obtained.

(Second Embodiment)
Next, a second embodiment will be described. This embodiment is different from the first embodiment in that the linerless cylinder block 21 is a target, and other members such as the piston 3 have the same configuration. Therefore, the same elements as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  Based on FIG. 3, the schematic structure of the cylinder block 101 of this embodiment is demonstrated.

  As shown in FIG. 3, the cylinder block 101 is provided with a cylinder bore 105 for accommodating the piston 3 so as to be able to reciprocate up and down. For example, the cylinder block 101 is made of cast iron, chrome cast iron, or the like and is formed by casting. The cylinder bore 105 has a circular cross section and extends vertically, and the piston 3 is slidably accommodated therein. An inner peripheral surface (hereinafter referred to as “bore inner peripheral surface”) 106 of the cylinder bore 105 is subjected to a scuffing prevention surface treatment for preventing seizure with the piston 3.

  As in the first embodiment, the scuff prevention surface treatment of this embodiment is performed by performing shot peening on the bore inner peripheral surface (sliding surface with the piston 3) 106 using a fine particle shot material made of molybdenum disulfide. In the bore inner peripheral surface 106, molybdenum disulfide is embedded.

  Thereby, also in this embodiment, the same effect as 1st Embodiment is acquired, and sliding resistance with piston 3 can be reduced, preventing scuffing.

1 Cylinder liner 2 Engine 3 Piston 5, 105 Cylinder bore 6, 106 Bore inner peripheral surface 21, 101 Cylinder block

Claims (2)

A cylinder formed of boron cast iron or cast iron in which a cylinder bore that slidably accommodates a piston of an engine is formed and a surface treatment is applied to the inner peripheral surface of the cylinder bore to prevent seizure with the piston In the liner,
The surface treatment uses a fine particle shot material made of molybdenum disulfide having a particle diameter of 5-20 μm , and only a part of the molybdenum disulfide that collides with the inner peripheral surface of the cylinder bore collides with the inner peripheral surface of the cylinder bore. Shot peening is performed so as to be embedded in the inner peripheral surface of the cylinder bore, dimples made of molybdenum disulfide are formed on the inner peripheral surface of the cylinder bore, and a part of the molybdenum disulfide is 1-2 μm on the inner peripheral surface of the cylinder bore. Cylinder liner characterized by being embedded. In the cylinder block in which the cylinder bore that slidably accommodates the piston of the engine is formed of cast iron or chrome cast iron, and the inner peripheral surface of the cylinder bore is subjected to a surface treatment for preventing seizure with the piston.
The surface treatment uses a fine particle shot material made of molybdenum disulfide having a particle diameter of 5-20 μm , and only a part of the molybdenum disulfide that collides with the inner peripheral surface of the cylinder bore collides with the inner peripheral surface of the cylinder bore. Shot peening is performed so as to be embedded in the inner peripheral surface of the cylinder bore, dimples made of molybdenum disulfide are formed on the inner peripheral surface of the cylinder bore, and a part of the molybdenum disulfide is 1-2 μm on the inner peripheral surface of the cylinder bore. Cylinder block characterized by being embedded.

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