JPS6035522B2 - Sealing device between cylinders of multi-cylinder two-stroke engine - Google Patents

Abstract

PURPOSE:To secure intercylindrical sealing characteristic by utilizing the viscosity resistance, surface tension and frictional force of oil with a labyrinth groove and a clearance facing with the groove used as oil passage. CONSTITUTION:A labyrinth packing 33, a ringed member is fixedly fitted between the bearing supprot inner-cylindrical faces 4 and 5 of upper and lower crank cases 2 and 3. The face 24 is provided with a number of ringed grooves 6. The face 24 and the outer cylindrical face 29 of a collar 8 face with each other with a small ringed clearance provided therebetween. An oil hole 31 opens at a ringed land 30 at the intermediate part of the face 24. During the operation of an engine, the oil discharged from a oil pump passes through an oil passage 11, an oil hole 31 and land 30, and fills the clearance between the faces 24 and 29 and is divided in two and is supplied to the main bearings 12 and 12 on the both sides of a collar 8. The oil having passed the main bearing 12 enter an oil receiver 18 via an oil slinger 13, and an oil passage 16 while receiving centrifugal force, and is supplied to a large end bearing 20 via an oil passage 17.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inter-cylinder sealing device in a crank chamber compression type multi-cylinder two-stroke engine.

Conventionally, a labyrinth packing as shown in FIG. 1 has been widely used as a non-contact sealing device. In FIG. 1, the labyrinth packing is a ring-shaped one inserted on the outside of the collar 8, which is fixed to the bearing support inner cylindrical surfaces 4, 5 of the upper and lower crankcases 2, 3 by a sandwiching method, and has a large number of annular grooves 6.
The inner cylindrical surface having a labyrinth groove is opposed to the outer cylindrical surface of a collar 8 fixed on the inter-cylinder rotation shaft 7 with a slight gap therebetween, and a thin oil hole 9 parallel to the rotation shaft 7 is formed. A radial oil hole 10 is provided in the middle thereof, and the oil hole 10 is connected to the discharge port of the oil pump through an oil passage 11 in the crankcase 2. 12 is a pair of main bearings, 13 is an oil slinger fixed to the bearing support inner cylindrical surfaces 4 and 5, 14 is a crank arm, 15 is a crank pin, 16 and 17 are oil passages, 18 is an oil receiver, 19 is a connecting rod big end, and 20 is a big end bearing.

However, as shown in Fig. 1, if the seal part (labyrinth packing part) consisting of the annular groove 6 and collar 8 is separated from the oil hole 9 which becomes the oil passage, {1} In order to have a labyrinth effect, the rotating shaft (collar 8) must be separated. It is necessary to keep the dimension between the fixed sealing member (labyrinth packing 1) and the fixed sealing member (labyrinth packing 1) extremely small, for example, on the 0.1 side, and strict processing accuracy is required.

Furthermore, the length of the marrow in all directions requires a certain amount of length, which limits the dimension between the cylinders. ■ Even if the gap is sufficiently small and the length is sufficiently large, a complete seal is impossible, and a decrease in output performance due to this is unavoidable.

[3} In order to avoid contact between the rotating shaft and the fixed member, it is necessary to widen the gap to an extent that can absorb shaft vibration, but doing so will sacrifice the labyrinth effect.

{4) It takes time and effort to process the oil holes 9 in the lapirin packing l.

On the other hand, when a contact type sealing device such as an oil seal is adopted, an extremely special material with heat resistance is required because the rotating shaft portion between the cylinders is the part that is least cooled.

'2} The sealing function decreases due to wear of the contact parts, resulting in insufficient durability.

(3) There are problems such as unavoidable mechanical losses.

In order to solve the above-mentioned problems, the present invention uses the labyrinth groove and the gap facing it as an oil passage to ensure sealing performance between the cylinders by utilizing the viscous resistance, surface tension, and inertia of oil. An example is shown in FIG.

In FIG. 2, the same symbols as those in FIG. 1 indicate corresponding parts.

The labyrinth packing 23 shown in FIG. 2 is a ring-shaped member that is fixed to the bearing support inner cylindrical surfaces 4 and 5 of the upper and lower crankcases 2 and 3 by a sandwiching method, and the inner cylindrical surface 24 has a large number of annular grooves 6. The inner cylindrical surface 24 and the outer segment surface 2 of the collar 8 are provided.
9 are opposed to each other with a slight annular gap therebetween, and an oil hole 31 is closed in an annular land 30 (a portion between the annular grooves 6, 6) provided in the middle of the inner cylindrical surface 24. 32 is a circle ring.

In order to prevent uneven flow of oil in the gap, the collar 8 and the labyrinth packing 23 are made of molded products or die-cast products that are symmetrical with respect to the land 30, and the accuracy of the inner and outer cylindrical surfaces 24, 29 is improved. The method of increasing is effective. While the engine is running, oil (lubricating oil) discharged from the oil pump passes through the oil passage 11 and the oil hole 31 to the land 3.
0 fills the gap between the inner and outer cylindrical surfaces 24 and 29, and is divided into two parts and supplied to the main bearings 12 and 12 on both sides of the collar 8.

The lubricating oil that has passed through the main bearing 12 passes through the oil slinger 13, enters the oil receiver 18, receives centrifugal force, enters the oil passage 16, passes through the oil passage 17, is supplied to the large machine bearing 20, and is lubricated. From there, the oil scatters into the crank chamber 21 and is supplied to a sliding portion (not shown) between the cylinder and the piston. As described above, according to the present invention, '1) Since the gap between the collar 8 and the lapillin packing 23 is filled with oil discharged from the oil hole 31, the gap between the labyrinth packing 23 and the crank chamber 21 of the cylinder on the left and the cylinder on the right The seal between the cylinder's crank chamber (not numbered) is ensured.

That is, in general, adjacent cylinders of a multi-cylinder two-stroke engine usually have a phase difference of 180 degrees, and in a stroke (crank chamber compression stroke) in which the crank chamber 21 of the cylinder on the left side of the lapillin packing 23 is compressed by the downward movement of the piston, Since the piston of the right cylinder is rising, the pressure inside the crank chamber is negative. Therefore, the pressure difference between the crank chambers of adjacent cylinders increases. In such a case, in the present invention, since the cross-sectional area perpendicular to the axial direction of the gap formed by the plurality of annular grooves 6 increases or decreases with each position in the axial direction, the pressure difference causes the gap to close. Even if the lubricating oil in the crank chamber 21 tries to flow in one direction, the gap with a complex cross-sectional shape provides a large resistance to the flow of the lubricating oil, and the gas pre-pressurized in one crank chamber 21 is blown into the other crank chamber through the gap. It is possible to reliably prevent the problem of it coming off. ■ Even when the viscosity of the lubricating oil supplied from the oil hole 31 is low, due to the gap between the tooth-shaped inner circumference of the labyrinth packing 23 and the collar 8, the flow resistance increases for the same reason as in the previous section. The lubricating oil becomes difficult to flow, and the lubricating oil becomes difficult to flow on both wall surfaces (outer cylindrical surface 29 of collar 8 and lapillin packing 2) where the lubricating oil forms a gap.
3, the inner cylindrical surface 24, annular groove 6, etc.) and plays the role of a plug, and exhibits sealing properties against blow-by of pre-pressure gas in the crank chamber 21. That is, gas blow-by can be effectively prevented as in the case where the lubricating oil has high viscosity. '3- The clearance between the inner and outer cylindrical surfaces 24 and 29 can be made larger than before, making processing easier.

'4} Inner and outer cylindrical surfaces 24 and 29 to relieve vibration of the rotating shaft
Even if the gap is increased, the sealing performance will not deteriorate because the area is filled with lubricating oil. [5} Compared to the one shown in FIG. 1, there is no need to provide axial fine holes (oil holes 9), so the machining of the labyrinth packing 23 becomes easier.

[6] Since a method is adopted in which lubricating oil is supplied from the oil hole 31 in the middle of the length of the labyrinth packing 23, the oil pressure in the gap between the labyrinth packing 23 and the collar 8 is at the middle of the length of the labyrinth packing 23. The portion (the oil hole 31 portion) is the highest, the both ends are the lowest, and there is a smooth change in between.

Therefore, in addition to the fact that the gap is filled with lubricating oil that acts as a plug, when the preload gas tries to blow through from the crank chamber 21 of the left cylinder to the crank chamber of the right cylinder, or vice versa. Even when the preloaded gas tries to blow through from the right-hand crank chamber to the left-hand crank chamber, it is possible to provide a similar amount of resistance, and there is an advantage that an equal sealing effect can be exerted on the crank chambers of both cylinders. Note that when embodying the present invention, the annular groove may be provided on the outer cylindrical surface 29 of the collar 8, or may be provided on both the inner and outer cylindrical surfaces 24 and 29.

The thickness of the labyrinth packing 23 may be increased by omitting the collar 8, or the portion corresponding to the labyrinth packing 23 may be provided integrally with the crankcases 2 and 3.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a conventional non-contact type sealing device, and FIG. 2 is a longitudinal cross-sectional view of a sealing device according to the present invention. 2, 3... Upper and lower crankcases (engine body),
6... Annular groove, 7... Inter-cylinder rotating shaft,
23... Lapilin packing, 24... Inner cylinder surface, 29... Outer cylinder surface, 31... Oil hole. Figure 1 Figure 2

Claims (1)

[Claims] 1. A large number of annular grooves are provided in one or both of the outer cylindrical surface of the inter-cylinder rotating shaft and the inner cylindrical surface on the side of the engine body that surrounds the outer cylindrical surface and has a diameter slightly larger than the outer diameter, An inter-cylinder sealing device for a multi-cylinder two-stroke engine, characterized in that a substantially intermediate position of a cylindrical gap between a cylindrical surface and an inner cylindrical surface on the engine main body side is connected to a hydraulic power source.