JPS6157931B2 - - Google Patents

Abstract

PURPOSE:To securely lubricate a turbine shaft, by a method wherein an expansion chamber maintained substantially at the atmospheric pressure is provided which is substantially shielded from the interior space of an engine casing below a piston, and the expansion chamber is communicated with an oil return passage. CONSTITUTION:A turbosupercharger 8 is provided, a lubricating oil contained in an oil pan 21 provided at the lower part of an engine casing 11 is fed to a turbine shaft 14, and thereafter the oil is returned to the oil pan 21 through an oil return passage 25. In said engine, the expansion chamber 26 maintained at approximately atmospheric pressure is provided which is communicated to the interior of the oil pan 2 and substantially shielded from the interior space A of the engine casing 11 below the piston 5 so that it is not affected by variations of the pressure inside the space A, and the chamber 26 is communicated to the passage 25. Accordingly, the lubricating oil can be returned to the oil pan side irrespectively of the variations in the pressure of a blow-by gas, and the turbine shaft 14 can be securely lubricated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a lubricating device for an engine equipped with a turbocharger that is driven by engine exhaust gas and supplies supercharging air to the engine, and in particular a lubricating device for a turbine shaft of a turbocharger. This invention relates to improvements in lubrication structures.

Conventionally, as a structure for supplying lubricating oil to the turbine shaft of the above-mentioned turbocharger, Japanese Patent Laid-Open No. 140013/1983 discloses a structure in which the engine is started using an electric oil motor that is separate from the oil pump driven by the engine. A structure is disclosed in which lubricating oil is supplied to the turbocharger at certain times, and the supplied lubricating oil is collected into the oil tank.

However, in the above structure, the lubricating oil in the oil pan provided below the engine case is sent to the turbine shaft of the turbocharger, and then the lubricating oil is recovered into the oil pan via the oil return passage. Because of this system, there is a problem of insufficient lubrication to the turbine shaft, as will be explained below.

In other words, inside the engine casing below the piston with which the oil return passage communicates, pressure fluctuations occur due to blow-by gas leaking from the combustion chamber (working chamber) and the vertical movement of the piston, and this pressure fluctuation is directly transferred to the oil return passage. also acts,
There is a problem in that the lubricating oil used to lubricate the turbine shaft is not smoothly returned to the oil pan side, resulting in insufficient lubrication of the turbine shaft.

The present invention was made in order to solve this problem, and it is an object of the present invention to smoothly distribute the lubricating oil used for lubrication of the turbine shaft through the oil return passage, that is, without regard to pressure fluctuations in the crankcase due to blow-by gas. The object of the present invention is to provide a lubricating device for a turbocharged engine that allows the oil to flow back into the oil pan.

Therefore, in the present invention, the oil pan is connected to the inside of the oil pan provided below the engine casing, and the upper part of the oil level is substantially different from the engine casing inner space so as to avoid pressure fluctuations in the engine casing inner space below the piston. The present invention is characterized in that an expansion chamber at approximately atmospheric pressure that is isolated from the outside is provided, and the expansion chamber and the oil return passage are communicated with each other.

Hereinafter, the present invention will be described in more detail based on illustrated embodiments.

In the drawing, 1 indicates a cylinder body 2, a cylinder head 3, a piston 5 that reciprocates vertically within a cylinder bore 4 at the top of the cylinder body 2, and a system that converts the reciprocating motion of the piston 5 into rotational output via a connecting rod 6. The engine 1 has a crankshaft 7 as a basic component, and is equipped with a turbo supercharger 8 for supplying supercharging air.

This turbo supercharger 8 has a casing 11 attached to a portion where an intake passage 9 and an exhaust passage 10 are close to each other and parallel to each other, and a turbine 12 is rotated by exhaust gas flowing down the exhaust passage 10. is transmitted to a blower 15 facing the intake passage 9 via a turbine shaft 14 supported by a pair of bearings 13, 13. Supply to chamber 16. The intake and exhaust passages 9 and 10 are opened and closed by intake and exhaust valves 17 and 18, respectively, which are operated at appropriate timing in synchronization with the rotation of the engine 1.
They are connected to exhaust ports 19 and 20, respectively.

On the other hand, 21 is a skirt portion 2a of the cylinder body 2.
The oil pan has an upper edge flange 21a fixed to the lower end flange 2b (of the engine casing below the piston 5), and stores an appropriate amount of lubricating oil inside, supplying the lubricating oil necessary for each lubricating part of the engine 1. Do this. Although not specifically shown, this lubricating oil is supplied by an oil pump driven by the engine 1, and in order to lubricate the turbine shaft 14 of the turbocharger 8, an oil passage in the cylinder head 3 is supplied. Oil supply passage 2 with one end communicating with 22
3, and the other end of this oil feed passage 23 is communicated with an oil jacket 24 formed between a pair of bearings 13, 13 of the turbo supercharger 8.

As shown in the drawing, the oil jacket 24
The lubricating oil used to lubricate the turbine shaft 14 inside is returned from the oil jacket 24 to the oil pan 21 side through the oil return passage 25.

In the present invention, the lower end of this oil return passage 25 is connected to an expansion chamber 2 communicating with the inside of the oil pan 21.
It communicates with the upper part of 6. This expansion chamber 26 is
In this embodiment, a part of the side wall of the oil pan 21 is provided with a bulged wall portion 27 that bulges out laterally, and this bulged wall portion 27.
A closed space is formed by a partition wall 28 that partitions the cylinder body 2 and the oil pan 21 side, and a protrusion wall 29 that protrudes the lower end flange portion 2b of the cylinder body 2 laterally. The partition wall 28 extends to the lower surface of the lower end flange portion 2b of the skirt portion 2a so as to substantially isolate the expansion chamber 26 from the internal space A of the engine casing below the piston 5.
A throttle communication port 30 is provided that partially communicates the bottom of the expansion chamber 26 and the bottom of the oil pan 21.

Further, the expansion chamber 26 is communicated with the atmosphere through an atmosphere communication pipe 31 whose base is inserted into a mounting hole of the protruding wall 29, thereby maintaining the internal pressure of the expansion chamber 26 at atmospheric pressure. There is.

In the above configuration, the internal pressure of the expansion chamber 26 is maintained at atmospheric pressure, so atmospheric pressure always acts on the lower end side of the oil return passage 25, and the oil jacket 24 of the turbocharger 8 The oil pressure is
The lubricating oil is supplied by an oil pump, and since the pressure is higher than atmospheric pressure, the lubricating oil flows smoothly into the expansion chamber 26.
It is refluxed into the interior. That is, the oil return passage 25
The lubricating oil can be recirculated without being affected by pressure fluctuations that may occur in the engine casing internal space A below the piston 5, and the lubricating oil supply amount and recirculation amount can be adjusted in the oil jacket 24. With this balance, the turbine shaft 14 can be effectively lubricated.

Furthermore, the lubricating oil returned to the expansion chamber 26 is returned to the oil pan 21 through the throttle opening 30. In this case, the pressure fluctuation in the engine casing internal space A below the piston 5 is caused through the throttle opening 30.
Although it may be transmitted through the distribution of lubricating oil,
There is no problem because the diaphragm opening 30 can substantially block the above-mentioned pressure fluctuation due to its diaphragm effect.

The present invention is not limited to the structure of the embodiment described above.

For example, the partition wall 28 does not need to completely partition the engine casing internal space A below the piston 5 from the expansion chamber 26, and the throttle opening 30 may open from the bottom of the oil pan to slightly above the lubricating oil level. In other words, a small gap may be formed between the oil level and the upper edge of the throttle opening, in short, pressure fluctuations in the internal space A are alleviated and pressure fluctuations in the oil return passage 25 do not have an adverse effect. It is fine as long as it is something. In addition, the atmospheric communication pipe 31 is not necessarily necessary, and a member having a relief function that relieves the internal pressure only when the internal pressure of the expansion chamber 26 reaches a predetermined pressure higher than atmospheric pressure is used. Expansion room 2
6 may be maintained at a level that does not interfere with the recirculation of the lubricating oil. Furthermore, the portion where the expansion chamber 26 is formed is not limited to the above embodiment.

As is clear from the above description, according to the present invention, an expansion chamber at approximately atmospheric pressure is provided in which the hydraulic upper part is substantially isolated from the internal space of the engine casing below the piston, and the expansion chamber is used to lubricate the turbine shaft. Since the oil return passage for the lubricating oil supplied to the engine is communicated with the lubricating oil, the lubricating oil can be returned to the oil pan side regardless of pressure fluctuations caused by blow-by gas, and lubrication of the turbine shaft can be ensured.

[Brief explanation of the drawing]

The drawing is an explanatory vertical cross-sectional view of an engine showing a lubricating device for a turbocharged engine according to the present invention. 1...Engine, 2...Cylinder body, 8...
Turbo supercharger, 21...Oil pan, 23...Oil feed passage, 25...Oil return passage, 2
6... Expansion chamber, A... Engine casing internal space below the piston.

Claims (1)

[Claims] 1. A turbocharger is provided, and after lubricating oil in an oil pan provided below an engine casing is supplied to a turbine shaft of the turbocharger, the lubricating oil is sent to the oil pan via an oil return passage. In an engine designed for recirculation, there is an approximately large area that communicates with the inside of the oil pan and is substantially separated from the internal space of the engine casing below the piston so as to avoid pressure fluctuations in the internal space of the engine casing. A lubricating device for a turbocharged engine, characterized in that an air pressure expansion chamber is provided, and the expansion chamber communicates with the oil return passage.