JPS6298069A - Piston having roller bearing - Google Patents

Abstract

PURPOSE:To make it possible to reduce friction losses, by arranging roller bearings between the skirt section of the a piston and a cylinder. CONSTITUTION:Four rollers are arranged in the skirt section of a piston 1, being spaced in the vertical directions and located at positions which are opposed to each other. Meanwhile, a predetermined gap is taken between the land section 3 of the piston 1 and a cylinder liner 2. Accordingly, there are no members which are adapted to slide between the piston 1 and the cylinder liner 2, other than compression rings 9, 10 and an oil ring 11, and the rollers 4 make into rolling-contact with the cylinder liner 2, thereby it is possible to greatly reduce friction losses between the piston 1 and the cylinder liner 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piston sliding portion (i.e.,
The feature is that a rolling bearing is used in the part that comes into contact with the liner wall.

Conventional pistons and liners have been in contact through "sliding contact" between the outer surface of the piston and the inner surface of the liner, but future technological innovations have the following problems.

(A) Problems in reducing friction loss The "sliding contact" between the piston and liner is a movement accompanied by severe changes in speed and direction, and especially in the case of reciprocating engines, it is a movement under high temperature conditions. , the lubrication conditions are very strict. Because of this, its "sliding contact"
The friction loss caused by this is quite large, and is a serious barrier to increasing the efficiency of equipment in the future.

(B) Problems associated with making the device lubrication-free In recent years, especially in the field of reciprocating engines, with the development of new materials (for example, the development of ceramics), it has been sought to make the device lubrication-free and non-cooling. In other words, new materials are being introduced into each moving part of the equipment to enable operation without lubrication or cooling.

The aim is to eliminate the need for lubricating oil and cooling water, thereby eliminating the need for auxiliary equipment to supply them and improving mechanical efficiency. It also aims to improve thermal efficiency by preventing combustion energy from escaping into lubricating oil and cooling water.

Specifically, instead of "sliding bearings" for each journal,
"Rolling bearings" using ceramic rollers and balls
By using a lot of , we are trying to eliminate lubrication. However, since the movement of the piston is axial sliding within the cylindrical surface of the liner, conventional "rolling bearings" cannot be used. Therefore, the seizure resistance of the new material itself
'1ilFi relies on its abrasion properties to increase the reliability of "sliding contact" under non-lubricated conditions.

However, the conditions are extremely harsh, and even new materials cannot meet the reliability requirements and are facing a major hurdle.

(C) Problems in Noise Reduction In order to enable good "sliding contact" between the piston and liner, it is necessary to provide an appropriate oil clearance between them. However, when the pistons and connecting rods change their direction of motion rapidly, or during an explosion in a reciprocating engine, the oil clearance causes the pistons to violently slam against the liner wall, producing a banging sound.
(This is called piston slap noise.) This slap noise occupies a large part of the overall noise of the device and is a barrier to noise reduction.

Furthermore, in reciprocating diesel engines, slapping noise is often a problem immediately after starting or during partial load.
(This is because if the oil clearance at full load is optimally designed, the piston's heat contraction system will exceed the cylinder's heat contraction rate immediately after startup or at partial load, resulting in an increase in oil clearance and louder slapping noise.) ) The problems of the prior art have been explained above.

As a means to overcome these problems, we invented a piston that uses "rolling contact" instead of "sliding contact."

Hereinafter, examples of the structure will be explained one by one. That is, as a typical example, pistons of structure A1 structure B1 structure C for a reciprocating diesel engine will be explained.

ff construction A: "Piston with rolling bearing" for reciprocating diesel engine Aim: Reduction of friction loss See Figures 1 to 5 (a) Piston 1 and liner 2 are not in contact at land portion 3. However, it has a certain amount of clearance.

(b) The piston 1 and the liner 2 are in "rolling contact" via the rollers 4.

(c) Piston l has a total of four rollers 4,
These four pieces maintain reciprocation and suppress tilt movement.

(d) The outer peripheral surface of the roller 4 has approximately the same radius as the inner surface radius of the liner 2 so as to conform to the inner surface of the liner 2.

(e) The roller 4 is held by a shaft 6 via a needle bearing 5.

The shaft 6 is inserted into a hole provided in a support wall 7 protruding from a pin post portion 8 of the piston 1 and is held therein.

(G) The piston 1 has a compression ring 9.1.
0 and oil mist 11 are incorporated, and are responsible for the combustion gas seal and lubricating oil seal, respectively.

Structure A is no different from a conventional reciprocating diesel engine except for the use of a "rolling bearing" in the piston.

The method of using lubricating oil is also the same as before. That is, the outer circumferential surfaces of the needle bearing 5 and the roller 4 are lubricated by oil applied to a spring, oil mist within the device, or oil jetted from a piston cooling nozzle.

Therefore, roller 4. Needle bearing 5. shaft 6
The material used is common iron or aluminum to ensure reliability. In addition, from the viewpoint of improving wear resistance, it is also possible to use ceramic materials.

The reliability of the compression rings 9, 10 and the oil ring 11 can also be ensured by using conventional designs and materials. The piston 1 can be made of either cast iron or aluminum, but FIGS. 1 to 5 are based on a cast iron design.

The advantages of a piston with structure A are as follows.

(a) By adopting a "rolling bearing" in the sliding part of the piston, "sliding contact" (movement with severe changes in speed and direction under high temperature conditions, and at a certain timing, lubricating oil (Slip that does not occur through
It is possible to significantly reduce friction loss compared to the conventional method.

(b) Increased reliability against seizure between the piston and liner, which is mainly caused by oil film tearing during high-speed operation.

(c) Conventionally, the piston had a "sliding contact", which required a large sliding surface, but by adopting a "rolling bearing", a very compact design is possible. For reference, the dimensions and
A comparison of weights is shown in Table 1.

Table 1 Comparison of weight and dimensions of each piston - Values are indexes with aluminum piston as 100 - Compression height is from the center of the pin to the top surface.

Structure B: "Piston with rolling bearing" for reciprocating diesel engine Aim: No lubrication See Figure 6 Structure B is based on the structure A described above. However, since this assumes operation with lubricating oil and the material of each component differs from that of the piston silling, only this point will be explained.

The parts whose explanation is omitted are the same as structure A.

(a) The piston 101 has a compression ring 1
Only 09 and 110 are incorporated and are responsible for sealing combustion gas.

(b) Since there is no lubricating oil, an oil ring is not necessary.

(c) Inner surface of liner 102, compression ring 1
The outer circumferential surfaces of Nos. 09 and 110 are coated with a ceramic material to enable lubrication-free operation.

(d) Roller 104. Needle bearing 105. The shafts 106 are themselves ceramic-based or coated with a ceramic-based material to allow lubrication-free operation.

In structure B, a "rolling bearing" using a /1'7 material such as a ceramic material is used in the piston sliding part, thereby making it possible to operate the device without lubrication.

The advantages of a piston with structure B are as follows.

(a) By making it possible to operate without lubrication, an oil pump is no longer necessary, improving mechanical efficiency.

(b) Combustion energy can be prevented from escaping into the lubricating oil, and thermal efficiency can be improved.

(c) In addition, the Uke inherits the advantages of the structure A described above. In particular, it is more effective than structure A in reducing friction loss. This is because there is no oil ring, which has the largest friction loss among piston rings.

Structure C: "Piston with rolling bearing" for reciprocating diesel engine Aim: Noise reduction See Figures 7 to 10 Structure C is based on the structure A described above. The lubricant is
It is powered by an oil pump, replacing a traditional reciprocating diesel engine.

However, this differs from Structure A in that the roller is inserted into the inner surface of the liner using lubricating oil pressure to eliminate piston slap noise, so this point will be explained below.

The parts whose explanation is omitted are the same as in structure A.

(a) The lubricating oil is guided to the small end bushing by the connecting rod oil hole 214 provided inside the connecting rod 212.

(b) The small end bushing has /IX end bushing oil groove 215.
I'm being kicked.

(c) Lubricating oil is guided from the small end bush oil groove 215 to the piston pin rotation stopper 217 via the piston pin internal oil hole 216 provided in the piston pin 213.

(iv) The lubricating oil passes through the piston pin rotation stopper 217, passes through the oil chamber 218, pushes up the pawl valve 219, and is stored in the hydraulic chamber 221.

(e) In the hydraulic chamber 221, a constant hydraulic pressure is maintained inside by the spring 220 and the pawl valve 219 functioning as a check valve.

(f) This constant oil pressure acts on the flat portions 223 at both ends of the shaft 206 via the plunger 222, and constantly tries to push the shaft 206 outward.

(g) As a result, the two rollers 204 on one side are always pressed against the inner surface of the liner 202.

(H) As a result, the clearance between the roller 204 and the liner 202 becomes zero under any operating conditions. Also,
Even after long-term operation, the clearance becomes zero even when wear has progressed.

(In January, the shaft 206 provided on the support wall 207
The fixing hole has an oval shape and allows the shaft 206 to be moved in the left and right direction.

Structure C uses lubricating oil pressure to constantly press the rollers of the "rolling bearing" against the inner surface of the liner.
made possible.

The advantages of a piston with structure C are as follows.

(a) Piston slap noise can be reduced to zero, making it possible to significantly reduce equipment noise.

Furthermore, there is no increase in noise even after long-term operation.

(b) - Vibration of the liner can be suppressed to a low level, and cavity shimin pitching of the outer wall of the liner can be prevented.

(c) In addition, the Uke inherits the advantages of the structure A described above.

[Brief explanation of drawings]

The first blade is a front view of a "piston with rolling bearing" (hereinafter referred to as structure A) for a reciprocating diesel engine, which aims to reduce friction loss. FIG. 2 is a sectional view of Structure A, taken along the line II in FIG. FIG. 3 is a side view of structure A. FIG. 4 shows the structure A and the nn cross section Z in FIG. FIG. 5 is a sectional view taken along the line MI [I] of Structure A and FIG. Figure 6 is a front view of a ``piston with rolling bearing'' (referred to as structure B) for a reciprocating diesel engine that aims to eliminate lubrication. Figure 7 is a front view of a "piston with rolling bearing" (hereinafter referred to as Structure C) for a reciprocating diesel engine, which aims to reduce noise. FIG. 8 is a sectional view taken along IV-IV of FIG. 7 of structure C2. FIG. 9 is a perspective view illustrating the oil passage from the connecting rod to the piston via the piston pin in Structure C. FIG. 10 is a perspective view of the component 8 of the shaft holding hydraulic chamber of the "rolling bearing" of Structure C. 1, piston 2, liner 3, land portion 4, roller 5, needle bearing 6, shaft 7, support wall 8, pin post portion 9, compression ring (top) 10, compression ring ( Second) 11 is the oil ring 101, the piston 102, the liner 104, the roller 105, the needle bearing 106, the shaft 109, the compression ring (top) 110, the compression ring (second) 202, and the liner 204. , roller 206, shaft 207, support wall 212, connecting rod 213, piston pin 214, oil hole 215 in the connecting rod, small end bush oil groove 216, oil hole 217 in the piston pin, piston pin The rotation stopper 218, the oil chamber 219, the pawl valve 220, the spring 221, the hydraulic chamber 222, the plunger 223, the flat parts at both ends of the shaft.

Claims (1)

[Claims] In a device having a piston/crank mechanism, a rolling bearing is used in the sliding part of the piston.