JPS61135967A - Oil-supply free type two-cycle engine - Google Patents

Abstract

PURPOSE:To eliminate consumption of lubricating oil while lubricating sliding surfaces and bearing portions effectively, by constructing the entire mechanism of an engine extending from the sliding surface of a piston to bearing portions of a crankshaft in an noil-supply free structure. CONSTITUTION:A low-frictional and heat-resisting synthetic resin is applied over the outer surface of a piston 19 by way of flame spraying, and a piston ring 20 made of a low-frictional and heat-resisting synthetic resin is fitted to the outside of the piston 19. A piston pin 21 inserted to the piston 19 is fixed in place by means of a baffle pin 22. On the other hand, a bush 25 consisting of a dry bearing is inserted between the pin 21 and a small-end portion 24 of a connecting rod 23 connected to the pin 21. Further, an oil sealed type bearing consisting of a needle bearing 28, an outer race 29 and a pair of oil seals 30 is inserted between a crank pin 27 and a large-end portion 26 of the connecting rod 23.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application in Industry-1-) The present invention relates to an oil-free two-stroke engine used in, for example, a brush cutter.

(Prior art) A general two-stroke engine (for example, JP-A-56-2
No. 425), fuel oil is mixed with oil and air to form a mist, and the mixed oil is used to clean piston sliding surfaces, the small and large ends of connecting rods, and even the crankshaft. Normally, each bearing section is subjected to P slip.

Mixing oil into one fuel in this way not only wastes oil, but also requires a special mixing device and a special oil supply operation. Moreover, when oil is mixed with fuel and combusted, not only does the exhaust gas turn blue, but a large amount of carbon adheres to the combustion chamber, exhaust port, and muffler, resulting in a change in the volume of the combustion chamber and a decrease in the compression ratio. As a result, the output performance may be reduced, or the muffler's muffler muffling holes may become clogged, resulting in a loss of durability.

In addition, such carbon adheres to the piston surface,
Thermal problems were occurring due to poor heat dissipation of the piston. Furthermore, such carbon also adheres to the inside of the crankcase, and when the air is scavenged, it adheres to the sliding surfaces of the cylinders, which has the disadvantage that the sliding surfaces of the cylinders and rings become rough due to the adhesion of carbon. Ta. Carbon also adheres to the electrodes of spark plugs, which can cause bridging and short circuits, resulting in poor starting. Furthermore, when oil is used, the outside of the engine is contaminated by oil due to oil spillage or oil leakage during refueling, resulting in an inconvenience in that the appearance of the engine is impaired.

(Purpose of the Invention) This invention was made in view of the above problems, and eliminates oil consumption while maintaining the performance that sliding surfaces and bearing parts should have. The purpose is to eliminate the need for refueling, drastically reduce carbon sticking to various parts due to oil, and effectively maintain engine performance.

(Structure of the Invention) The present invention has been made to achieve the object stated in item 1. In this invention, a piston pin connecting a piston and a connecting rod is fitted around the piston, and the small end of the connecting rod and the piston A bearing provided between the pin, a bearing provided between the large end of the connecting rod and the crankshaft,
And, the crankshaft bearing is a dry type or oil-sealed type bearing, the piston ring is formed of a low-friction, heat-resistant synthetic resin, and the outer periphery of the piston is coated with a low-friction, heat-resistant synthetic resin. This allows the entire operating system within the engine, from the piston sliding surface to the crankshaft bearing, to be completely oil-free.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of a two-stroke engine configured primarily for a brush cutter.

Here, l is a crankcase made of aluminum material, and this crankcase 1 is a fan case 2.
It has integrally.

The crankcase 1 has shaft support walls 3.3 facing each other, and the crankshaft 4 is rotatably supported by these shaft support walls 3.3.

The crankshaft 4 in this case is supported by fitting both the first and second shaft support bearings 5.5 into the shaft support walls 3, 3, respectively. 5.5 is a sealed ball bearing having a sealing packing 6 made of a rubber plate. Here, - the above-mentioned first and second
The shaft support bearings 5.5 are arranged on the outside of the crankcase 1, while oil seals 7.7 are fitted inside each bearing 5.5.

In this way, with the oil seal 7.7 inside, the first and second
The reason why the shaft support bearing 5.5 is placed on the outside is as far as possible from the high-temperature gas in the crankcase 1.
This is to protect the second shaft support bearing 5.5 and effectively maintain the bearing function and sealing function.
Oil is filled between the oil seal 7.7 and the inner oil seal 7.7.

In this case, each of the above-mentioned bearings 5.5 is designed taking into account that while the crankcase 1 is made of aluminum, the crankshaft 4 is made of an iron-based material that has higher wear resistance than the crankcase 1. , crankcase 1
The crankshaft 4 is fitted tightly so as not to allow sliding, while the crankshaft 4 is fitted loosely. For this reason, the oil seal 7 is provided to prevent leakage of oil from between the first and second shaft support bearings 5.5 and the crankshaft 4 due to pressure fluctuations.

Further, as the first and second support bearings 5.5, for example, recently developed ceramic dry bearings can be used.

A cooling fan 9 having a mounting portion 8 for the brush cutter main shaft is attached to one end of the crankshaft 4 supported in this way protruding from the crankcase 1. Cooling air is taken in from the inlet 10, and the cooling air is also sent from the fan case 2 to the cylinder 11, which will be described later.

Further, a driven plate 13 that constitutes a part of the recoil starter 12 is attached to the other end of the crankshaft 4, and a drive side locking plate 11 that is engaged with this plate 13 is attached to the other end of the crankshaft 4.
4 is provided on a starter case 16 that is attached to a mounting portion 15 that integrally projects in an annular shape from the crankcase l.

= On the other hand, an aluminum cylinder 11 whose inner periphery is plated with Cr is attached to the upper part of the crankcase 1 to reduce friction, and this cylinder 11 includes a spark plug 18 that extends into the combustion chamber 17 and a piston 19. is provided.

Here, the piston 19 has low friction V7 on its outer peripheral surface! Coated with heat-resistant synthetic resin by thermal spraying.

As the coating material, fluororesin paint Xylan 7 (trade name, manufactured by Whitford, USA) NO1052, or Xylan (XYLAN)
R) (Trade name, USA Whitf.

No. 201 (manufactured by RD) is suitable. -1- General characteristics of the coating material include low friction, high wear resistance, and impact resistance.

A piston ring 20 is provided on the outer periphery of the piston 19.
The piston ring 20 in this case is made of a low-friction, heat-resistant synthetic resin, such as Vespel (trade name, manufactured by Teikoku Piston Ring Co., Ltd.), which is a super heat-resistant polyimide resin.

Further, the piston pin 21 fitted into the piston 19 is fixed to the piston 19 by a rotating pin 22 made of a spring pin. However, in consideration of the fact that the piston pin 21 is not only exposed to high temperatures but also subjected to high loads, the piston pin 21 is fixed to the piston 19 to eliminate the need for lubrication.

Note that other means such as splines may be used to prevent rotation.

On the other hand, a bushing 25 made of a dry bearing is fitted between the small end 24 of the connecting rod 23 connected to the piston pin 21 and the piston pin 21.

Furthermore, the following oil-sealed bearing is provided between the large end portion 26 and the crank pin 27.

That is, oil-sealed bearings in this case.

The needle bearing 28 arranged on the outer periphery of the crank pin 27, the outer race 29 on the outer periphery of the needle bearing 28, and the 1
It consists of a pair of oil seals 30 and 30.

The above-mentioned crankshaft 4 is of a type that is joined by a crank pin 27, and prior to this, the crankshaft 4 is joined by an inner groove 3 of a web 31.
2, the needle bearing 28 and outer race 29 are fitted between the big end 26 and the crank pin 27, and the opposing crankshaft 4 is connected to the press-fit type crank pin. The structure is such that they are connected at 27.

Here, the outer race 29 marked with "-" is filled with grease in advance, and a pair of oil seals 30, 30 are provided to prevent the grease from leaking out. In order to avoid interference between the connecting rod 30 and the connecting rod 23, a thrust gap 33 is provided between them, and by protecting the oil seal 30, grease leakage is effectively prevented.

FIG. 2 relates to a second embodiment, particularly to a type in which the crankshaft 4 is supported in a cantilevered manner.

Here, oil-sealed bearings are used for the small end m24 and the large end 26 of the connecting rod 23. However, the dry bearing shown at small end 24 in FIG. 1 may be selected if desired.

In the case of the second embodiment shown in FIG. 2, the recoil starter 12 is arranged at the lower part (corresponding to the side part in the actual machine) of the crankcase 1. Further, the first and second shaft support bearings 5.5 each have a pair of sealing gaskets 6.6 and are arranged in parallel.
, 5, an oil seal 7 is arranged between them.

Since the piston pin 21 is prevented from rotating by the piston 19 as described above, lubrication between the piston pin 21 and the piston 19 is not required.

In addition, the small end 24 of the connecting rod 23 and the piston pin 21
The bearing provided between the large end 26 of the connecting rod 23
The bearing provided between the crankshaft 4 and the bearing of the crankshaft 4 are dry type or oil-sealed bearings, and the piston ring 20 is made of a low-friction, heat-resistant synthetic resin. By coating the outer layer of 19 with a low-friction, heat-resistant synthetic resin, there is no need to replenish oil to the sliding surfaces of the entire operating system from the piston 19 to the crankshaft 4, as well as to the bearings. , it became possible to provide a so-called oil-free two-stroke engine.

As a result, the oil is not mixed with the fuel and burned.
Not only does the exhaust gas become transparent, but as a result, carbon does not arrive in the combustion chamber 17, the engine boat, and the muffler, resulting in a change in the volume of the combustion chamber 17, which lowers the compression ratio and reduces output performance. Also, the inconvenience of the muffler's muffler's muffling hole becoming clogged and impairing its durability is eliminated.

Further, since such carbon does not adhere to the surface of the piston 19, the heat dissipation performance of the piston 19 is not impaired, and therefore thermal troubles are less likely to occur. moreover,
Such carbon does not adhere to the inside of the crankcase 1. Therefore, when the carbon is scavenged, it does not adhere to the sliding surface of the cylinder 11, and the sliding surface of the cylinder 11 becomes inferior due to adhesion of carbon. It no longer becomes. Further, carbon does not adhere to the electrode portion of the spark plug 18, and therefore no bridging occurs, thereby eliminating the possibility of short circuits and starting failures. Furthermore, since no oil is used, the outside of the engine is not contaminated by oil due to oil spills or oil leaks during refueling, which eliminates the inconvenience of damaging the engine's appearance.

(Effects of the Invention) As explained above, according to the present invention, the entire working system in the engine from the piston sliding surface to the crankshaft bearing portion is completely oil-free, so the sliding surface and While effectively maintaining the lubrication performance of the bearing part, it eliminates oil consumption, eliminates the need for special equipment for oil mixing or refueling work, and dramatically reduces carbon adhesion to various parts due to oil, improving engine performance. can now be effectively maintained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of the invention, and FIG. 2 is a sectional view showing a second embodiment of the invention. 4... Crankshaft, 19... Piston, 20
... Piston ring, 21 ... Piston pin, 23
...Conrod, 24...Small end, 26...Large end.

Claims (1)

[Claims] (1) A piston pin that connects the piston and connecting rod is prevented from rotating on the piston, and a bearing is provided between the small end of the connecting rod and the piston pin, and a bearing is installed between the large end of the connecting rod and the crankshaft. The crankshaft bearings and crankshaft bearings are dry type or oil-sealed bearings, the piston rings are made of low-friction, heat-resistant synthetic resin, and the outer periphery of the piston is made of low-friction, heat-resistant synthetic resin. An oil-free 2-stroke engine featuring a coating.