JPH0742417U - Combination of piston and piston ring - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the piston ring from sticking. [Structure] The maximum clearance between the piston outer peripheral surface 2a and the cylinder bore inner peripheral surface 1a when the skirt portion of the piston 2 contacts the cylinder bore 1 and the chamfer 7 formed in the second ring groove 3 of the piston 2 The sum of the radial dimension is a, and the dimension between the radial inner end of the chamfer 6 of the second ring 4 in which the outer peripheral surface 4a is in contact with the inner peripheral surface 1a of the cylinder bore 1 and the inner peripheral surface 1a of the cylinder bore is b.
Then, there is a relation of a> b.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a combination of a piston and a piston ring, and is particularly effective when used in a diesel engine.

[0002]

[Prior art]

 The second ring mounted in the second ring groove of the piston is, for example, an undercut type, and the outer peripheral surface is formed with a plating film such as hard Cr plating. The upper corner of the outer circumference of the second ring is chamfered for the plating technology when coating the plating film and for the undercut type to adjust the twist amount of the ring. It is desirable to set this chamfer to a large value in order to reduce the twist of the ring.

Further, a chamfer is formed at an upper corner on the outer peripheral side of the second ring groove of the piston. This chamfer is formed with a size considerably smaller than the chamfer conventionally formed on the second ring.

[0004]

[Problems to be solved by the device]

 When the lubricating oil is exposed to high-temperature combustion gas during engine operation, carbon sludge is generated, and sludge 10 is formed at the upper corner on the outer peripheral side of the second ring groove 3 as shown in FIG. The chamfer 7A and the chamfer 6 formed at the upper corner of the outer periphery of the second ring 4 are attached and deposited.

Since the chamfering dimension is small in the second ring groove 3, the sludge 10 is attached from the chamfer 7A portion to the groove side surface 3a as shown in FIG. It is easy to deposit by making it stick out.

The sludge 10 deposited and deposited is removed to some extent by the piston 2 moving in the cylinder bore 1 in the radial direction and the like. That is, when the piston 2 moves from the position shown in FIG. 3 (a) to the position shown in FIG. 3 (b), the sludge 10 hits the corner 8 between the upper surface 4 b of the second ring 4 and the chamfer 6 and is crushed, and a part of the sludge 10 is crushed. Is removed.

However, the sludge 10 deposited on the chamfer 7A of the second ring groove 3 and the groove side surface 3a in the vicinity of the chamfer 7A and protruding toward the second ring 4 side has the following problem. Since the corner 8 of the second ring 4 does not hit, it remains without being crushed.

As a result, there is a risk that the second ring 4 may stick due to the sludge 10 that is attached and deposited on the second ring groove 3 and the second ring 4.

An object of the present invention is to prevent the piston ring from sticking.

[0010]

[Means for Solving the Problems]

 According to the configuration of the present invention, a piston and a piston in which a chamfer is formed on the upper corner of the outer circumference of the piston ring and a chamfer is also formed on the upper corner on the outer circumference of the piston ring groove formed in the piston. In the combination of rings, the maximum clearance between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder bore when the skirt of the piston comes into contact with the cylinder bore, and the radial dimension of the chamfer formed in the piston ring groove, Is a, and the dimension between the inner circumferential surface of the cylinder bore and the radially inner end of the chamfer of the piston ring whose outer circumferential surface is in contact with the inner circumferential surface of the cylinder bore is b, then a> b It is characterized by being.

[0011]

According to the above configuration, since the chamfered dimension of the piston ring groove is large, even if sludge adheres to the chamfered portion, it is prevented from projecting to the second ring side.

Further, even if the sludge should be deposited so as to project to the second ring side, the piston moves in the cylinder bore in the radial direction, etc., so that the angle between the upper surface of the piston ring and the chamfer is Since the sludge that sticks to and deposits on the chamfered portion of the piston ring groove hits the sludge protruding toward the piston ring side, the sludge portion protruding toward the piston ring side is crushed. As a result, sticking of the piston ring is less likely to occur.

[0013]

【Example】

 In FIG. 1, a piston 2 is inserted into a cylinder bore 1 of a cylinder block 9, and a second ring 4 is mounted in a second ring groove 3 formed in the piston 2. The second ring 4 is an undercut type in which the outer peripheral side end of the lower surface is notched, and a surface treatment layer 5 such as hard chrome plating is formed on the outer peripheral surface. A chamfer 6 is formed on the upper corner of the outer circumference of the second ring 4.

A chamfer 7 is also formed on the upper corner on the outer peripheral side of the second ring groove 3.

The chamfer 6 formed on the second ring 4 and the chamfer 7 formed on the second ring groove 3 are formed to have the following dimensional relationship. That is, as shown in FIG. 1, the maximum clearance between the piston outer peripheral surface 2a and the cylinder bore inner peripheral surface 1a when the skirt of the piston 2 contacts the cylinder bore 1 and the second ring groove 3 are formed. The sum of the radial dimension of the chamfer 7 is a, and the radial inner end of the chamfer 6 of the second ring 4 in which the outer peripheral surface 4a is in contact with the inner peripheral surface 1a of the cylinder bore 1 and the inner peripheral surface 1a of the cylinder bore. When the dimension of b is b, then a> b.

When the dimensional relationship of the chamfers 6 and 7 formed in the second ring 4 and the second ring groove 3 is as described above, the stick of the second ring 4 is prevented. This will be described below.

When the lubricating oil is exposed to high-temperature combustion gas when the engine is operating, carbon sludge is generated, and the sludge 10 has a chamfered 7 portion formed at the upper corner on the outer peripheral side of the second ring groove 3 and the second ring. It is formed in the upper corners of the outer periphery of the 4 deposited adhering to the surface up 6 parts are.

However, since the chamfer 7 of the second ring groove 3 is formed to be large, even if the sludge 10 adheres to the chamfer 7 portion of the second ring groove 3, the sludge 10 projects toward the second ring 4 side. Accumulation is prevented.

However, in some cases, sludge 10 may be deposited on the chamfered portion 7 of the second ring groove 3 so as to project toward the second ring 4 side, as shown in FIG.

However, as for the sludge 10 that has adhered and accumulated, the portion of the sludge 10 that protrudes toward the second ring 4 side is removed as the piston 2 moves in the cylinder bore 1 in the radial direction and the like. That is, when the piston 2 moves from the position of FIG. 2 (a) to the position of FIG. 2 (b), the portion of the sludge 10 protruding toward the second ring 4 side has a corner between the upper surface 4b of the second ring 4 and the chamfer 6. It is crushed at 8 and removed.

As a result, the second ring 4 is prevented from sticking.

The second ring stick test will be described below. The engine was a 2.2-liter, 4-cylinder, swirl chamber type diesel engine, and a stick test was performed at 4200 rpm × 4/4 load × 100 Hr.

The second ring groove and the second ring of each piston inserted in the four cylinder bores are configured as follows.

(1) Test Example 1 Second Ring Groove Chamfering: The upper corners on the outer peripheral side of the second ring groove of the pistons inserted in No. 1 and No. 3 of the cylinder are chamfered by C0.2 mm ( Conventional example). The upper corners on the outer peripheral side of the second ring groove of the pistons inserted in No. 2 and No. 4 of the cylinder are chamfered with C0.5 mm (the present invention).

Chamfering of second ring: The upper corner of the outer periphery of the second ring mounted in the second ring groove of each of the four pistons is chamfered by C0.5 mm.

In the 100 Hr stick test, in the combination of the second ring groove and the second ring in the cylinder No. 1 and No. 3 (conventional example), the sticking occurred in the second ring and the second ring groove in the cylinder No. 2 and No. 4 The second ring combination (invention) did not cause sticking in the second ring.

(2) Test Example 2 The upper corner on the outer peripheral side of the second ring groove of each piston inserted in all cylinders is chamfered by C0.5 mm, and is attached to the second ring groove of each piston. The upper corner of the outer circumference of the second ring is chamfered with C0.5 mm (all of the present invention).

In the 100 hr stick test, no sticking occurred in the second ring in all cylinders.

Although the second ring groove and the second ring have been described above, the chamfered dimensional relationship in the present invention is also effective when applied to the third ring groove and the third ring.

[0030]

[Effect of device]

 As described above, according to the present invention, it is possible to prevent the piston ring from sticking.

[Brief description of drawings]

1 is a longitudinal sectional view showing a second ring groove portion of a piston inserted in a cylinder bore according to an embodiment of the present invention, showing a state where a skirt portion of the piston is in contact with the cylinder bore.

FIG. 2 is a vertical cross-sectional view showing a second ring groove portion of a piston inserted in a cylinder bore, showing a sludge adhesion state, and FIG. 2 (a) shows that the piston is bent in a radial direction from a concentric position with the cylinder bore. Status,
(B) shows the state where the piston is bent in the opposite direction to (a) in the radial direction from the position concentric with the cylinder bore.

FIG. 3 is a vertical cross-sectional view of a conventional example showing a second ring groove portion of a piston inserted in a cylinder bore, showing a sludge adhesion state. (A) shows the piston in a radial direction from a concentric position with the cylinder bore. The warped state, (b), shows the state in which the piston is warped in the radial direction from the position concentric with the cylinder bore, and in the opposite direction to (a).

[Explanation of symbols]

 1 Cylinder Bore 1a Cylinder Bore Inner Surface 2 Piston 2a Piston Outer Surface 3 Second Ring Groove 3a Second Ring Groove Side 4 Second Ring 4a Second Ring Outer Surface 4b Second Ring Top 5 Surface Treatment Layer 6 7 Chamfer 8 Square 9 Cylinder Block 10 Sludge

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F16J 9/20

Claims (4)

[Scope of utility model registration request] 1. A piston and a piston ring in which a chamfer is formed on an upper corner of an outer circumference of a piston ring, and a chamfer is also formed on an upper corner on an outer circumferential side of a piston ring groove formed in the piston. In the combination of the maximum clearance between the piston outer peripheral surface and the cylinder bore inner peripheral surface when the skirt portion of the piston contacts the cylinder bore, and the radial dimension of the chamfer formed in the piston ring groove. Is a, and b is the dimension between the inner circumferential surface of the cylinder bore and the radially inner end of the chamfer of the piston ring whose outer circumferential surface is in contact with the inner circumferential surface of the cylinder bore. A combination of piston and piston ring. 2. The combination of piston and piston ring according to claim 1, wherein the piston and piston ring are used in a diesel engine. 3. The combination of a piston and a piston ring according to claim 1, wherein the piston ring groove is a second ring groove, and the piston ring is a second ring. 4. The combination of a piston and a piston ring according to claim 1, wherein the piston ring groove is a third ring groove, and the piston ring is a third ring.