JPS633382Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turbocharger for an internal combustion engine, and more particularly to an oil coking prevention device in the turbocharger housing.

Since turbochargers used in automobile engines reach high temperatures due to heat conduction from high-temperature exhaust gas, their main body housings are generally made of cast metal for their heat resistance and ease of manufacture. Further, lubricating oil from the engine is used to lubricate the bearings of the turboshaft of the turbocharger, and for this purpose oil passages for the lubricating oil are formed in the main body housing during casting. This oil passage has an inlet portion that introduces oil from the oil pan and an outlet portion that returns the oil after lubricating the bearing portion to the oil pan, and the outlet portion is located below the inlet portion. However, since the inner wall surface of this oil passage is a cast metal wall, the lubricating oil does not flow smoothly and tends to stagnate. As a result, the oil tends to become roasted due to the heat on the inner wall surface of the oil passage and accumulate as carbon-like deposits.

In particular, carbon deposits are likely to accumulate in the outlet section located below, which serves as an outlet for oil. If the carbon deposits accumulated in the outlet section progress upward, that is, toward the bearing section and inlet section, in the worst case, part of the oil passage may become clogged or the cross-sectional area may be reduced, resulting in damage to the bearing. This may result in insufficient lubrication of the bearings, causing wear and seizure of the bearings.

In view of the above-mentioned problems, the present invention has been developed by coating the inner wall surface of the main housing of the turbocharger (particularly the oil outlet section) with a resin layer that has excellent heat resistance, thereby making the inner wall surface of the housing smooth. Even if the lubricating oil that lubricates the bearing reaches the oil outlet, it does not stay there and returns to the oil pan quickly.This prevents oil coking due to the formation of lubricating oil deposits, which in turn can damage the turbocharger. The purpose of this is to improve the reliability of the system.

The present invention will be explained below with reference to embodiments shown in the drawings.

Reference numeral 1 indicates a main body housing (center housing) of the turbocharger, in which a compressor is attached to the right side in the figure, and an exhaust turbine (both not shown) is attached to the left side. The compressor and the exhaust turbine are connected by a turboshaft (not shown), and the rotation of the exhaust turbine is transmitted to the compressor via the turboshaft. The turboshaft has a bearing part (shaft hole) 2 formed in the main body housing 1,
2' and is rotatably supported via a float bearing (not shown) or the like. An oil passage is formed within the main housing 1 to lubricate the bearings 2, 2'. As mentioned above, the main body housing 1 is generally made of cast metal in view of its heat resistance and ease of manufacture. Therefore, the oil passage can be easily formed at the same time as the housing 1 is cast.

The oil passage includes an inlet passage 5 for introducing oil from an oil pump (not shown), and a horizontal hole 7 for branching oil from the inlet passage 5 to the bearing parts 2 and 2'.
and a connecting path 9 from the horizontal hole 7 to the bearing parts 2, 2',
9' and an outlet section 11 that collects oil that has lubricated the bearing section and returns it to an oil pan (not shown). The above is an example of a typical conventional oil passage.

In the above-described structure, the inner wall surface of the housing that forms the oil passage is cast as described above, so its surface is uneven, and therefore, the lubricating oil that has been transmitted is likely to stagnate and deposits are likely to be generated. There is. Therefore, according to the present invention, the inner wall surface of the housing is coated with a resin layer 13 (eg, polyimide) having excellent heat resistance.

As the resin layer 13, for example, a polyamide film (trade name: Kapton) developed by DuPont, which can be used even under high temperature conditions of 400°C, can be used, but the point is that if it is a heat-resistant layer, it does not necessarily have to be a resin layer. There isn't. Coating with the resin layer can be carried out, for example, by inserting an injection nozzle for coating from the bearing parts 2, 2' and spraying the resin onto the inner wall surface of the housing.

It is considered that carbon-like deposits are most likely to be formed in the oil outlet section 11 where oil is collected after lubricating the bearing.
Although it is sufficient to coat the resin layer (heat-resistant layer) 13 only on the inner wall surface of the housing forming the housing 1, it is of course possible to coat the entire oil passage from the inlet passage 5 to the outlet part 11. .

With the above structure, when the oil that has lubricated the bearing reaches the outlet, the surface is smooth, so the oil does not stay there and returns smoothly to the oil pan. Therefore, it is possible to prevent the formation and accumulation of deposits caused by steaming under high temperature conditions due to oil stagnation.

[Brief explanation of the drawing]

The drawing is a longitudinal view of a main body housing of a turbocharger having an oil coking prevention device according to the present invention. 1...Body housing, 2, 2'...Bearing part,
5... Inlet passage, 11... Outlet section, 13... Resin layer (heat resistant layer).

Claims (1)

[Scope of utility model registration request] In a turbocharger in which an oil passage for lubricating the bearing part is formed in the main body housing having a bearing part into which the turboshaft is inserted and supported, at least an outlet to the oil pan on the inner wall surface of the main body housing forming the oil passage. 1. An oil coking prevention device for a turbocharger, characterized in that a coating layer is formed on a portion thereof to have heat resistance and smooth the wall surface.