JPS6231170B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the diameter dimension of a lubricating oil supply passage in a center housing rotor assembly provided for lubricating each bearing metal of a supercharger, and is particularly suitable for improving durability. The present invention relates to a supercharger with a center housing rotor assembly having a passage system.

In the conventional lubricating oil supply passage system in the center housing rotor assembly as disclosed in Japanese Patent Application Laid-open No. 56-138421, the amount of oil supplied to the radial bearing metal portion is close to the minimum allowable oil amount. Because the cooling of the radial bearing metal was poor, carbon bridges (lubricating oil seizes on the metal surface and turns into carbon due to high temperatures when the engine suddenly stops from high-speed, high-temperature operation) may occur. There were drawbacks such as the inability to flush out the carbon.

The purpose of the present invention is to appropriately select the lubricating oil supply passage system in the center housing rotor assembly, to ensure the minimum amount of oil required for each part, and to increase the amount of oil supplied to the metal parts of the radial bearing, which poses a problem in terms of durability. It is an object of the present invention to provide a supercharger characterized in that the amount of oil supplied to the radial bearing metal part on the turbine side is further increased, and the durability is improved.

The feature of the present invention is to first determine the minimum amount of oil for cooling the piston ring part of each part of the lubricating oil passage system, and then to reduce the amount of oil supplied to the thrust bearing metal part to the required minimum amount. The lubricating oil passage to the metal is constricted to increase the amount of oil supplied to the metal part of the radial bearing.

Furthermore, the diameter of the supply passage to the radial bearing metal portion on the turbine side is made larger than that on the compressor side, thereby reducing the passage resistance and increasing the amount of oil on the turbine side.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 9.

FIG. 1 describes an overview of a supercharger and a conventional lubricating oil supply passage system. The supercharger consists of a center housing rotor assembly incorporating a turbine 12 and a compressor 13 in a center housing 7 having radial and thrust bearing metal, a turbine case 8 through which exhaust gas passes, and a compressor that supplies overpressurized air to the engine. It consists of case 9.

The lubricating oil seal mechanism of the center housing rotor assembly includes the following. A piston ring 15 is installed on the turbine side, and a piston ring 15 is installed on the compressor side.
It includes a mechanical seal mechanism formed by a seat ring 16, a driven ring 17, and a thrust spacer 18.

A compressor 13 rotates at high speed together with a turbine 12 driven by exhaust gas discharged from the engine. As a bearing mechanism for supporting a high-speed rotating body, bearing metals 19 and 20 that move in the radial direction at a rotation speed that is approximately half of the turbine rotation speed are incorporated in the center housing 7 while being supported by a circlip 21. . Further, in order to support movement in the thrust direction, the thrust bearing metal 22 is supported by a thrust spring 23 press-fitted into the back plate 10. These bearing metal parts are protected by lubricating oil pumped from the engine's main gear rally. The lubricant is
The lubricating oil is fed under pressure from the lubricating oil supply inlet 1 of the center housing and distributed to each passage. The passage system is composed of a piston ring cooling lubricating oil passage 2, a turbine side radial bearing metal lubricating oil passage 3, a compressor side radial bearing metal lubricating oil passage 4, and a thrust bearing metal lubricating oil passage 5. Hereinafter, these passages will be abbreviated as 2 for P, 3 for Mt, and 4 for abbreviation.
Mc, 5 are called T, and the respective passage diameters are D _P and D
We will call them _Mt , D _Mc , and _DT .

Since the turbine 12 is exposed to exhaust gas as high as 950 to 1000 degrees Celsius, a heat shroud 24 is incorporated to prevent radiant heat from being radiated to the center housing 7. In order to prevent lubricating oil from leaking from the turbine side, a piston ring 15 is incorporated, and lubricating oil is jetted out from P for cooling the piston ring 15. In order to reduce the heat resistance of the piston ring 15 and the heat conduction of the turbine side radial bearing metal, the minimum required oil supply quantity Q _P
is decided.

Next, the radial bearing metal is supplied with lubricating oil from Mt and Mc, respectively, and it is necessary to supply the minimum amount of oil Q _M that will not cause seizure of the metal. Similarly, there is also a minimum amount of oil Q _T to be supplied to the metal part of the thrust bearing. Figure 2 shows the characteristics of the oil pump discharge pressure PO of the main gear rally of the engine and the lubricating oil supply pressure that is supplied in a state where the pressure is reduced due to piping loss to the turbocharger. On the other hand, the boost pressure characteristics PC and turbine speed characteristics TN of the supercharged engine are shown in Fig. 3. Here, as a representative point, the turbine rotation speed N ₁ when the engine rotation speed is 2000 rpm is almost close to the maximum rotation speed. At this time, the turbocharger inlet supply pressure TI in Figure 2 has not yet reached the maximum oil pressure. Therefore, when the engine rotates at high speeds (3500 rpm or more), the lubrication state of the metal parts becomes better, and the thermal load on the metal parts is reduced. It can be seen that it is effective in terms of durability to supply a larger amount of oil to the radial bearing metal portion when the supplied oil pressure is low.

In addition, when a turbocharger suddenly comes to a sudden stop after driving on a highway, etc., the lubricating oil may seize on the metal part of the radial bearing on the turbine side due to heat conduction from the turbine side. These carbons are made of extremely hard or soft materials, and this accelerates the wear of the metal parts of the radial bearing. Also, the metal parts that are rotating at high speed are extremely hot. To improve the durability of the metal, we considered flushing out the carbon powder and increasing the amount of lubricating oil supplied to the radial bearing metal on the turbine side to improve the cooling effect.

First, the total passage area (D _P , D _Mt , D _Mc , D _T
The sum of the areas of
As shown in the figure.

Furthermore, the amount of oil supplied to each part at that time is shown in FIG. As can be seen from Fig. 5, the conventional oil supply amount has sufficient margin compared to the minimum oil amount for the thrust bearing, so as shown in Fig. 6, the thrust bearing metal lubricating oil supply passage in the center housing is By fixing the member 6 with the throttle by press-fitting or screwing, or by making the diameter of the lubricating oil supply port of the thrust bearing metal 22 equivalent to the area of the member 6 with the throttle, the supply passage can be formed. System (D _P , D _Mt , D _Mc ,
D _T ) increases the overall resistance. This results in
Since the oil pump discharge pressure of the engine is constant, the turbocharger inlet supply pressure increases by an amount corresponding to the increase in resistance, and the supplied oil amounts of D _P , D _Mt , and D _Mc increase by that amount.

The optimum diameter was experimentally confirmed in relation to the amount of oil supplied, and the results are shown in FIGS. 7-9.

From FIG. 7, the ratio of D _Mt /D _T is conventionally extremely small at 0.3. Therefore, as this is increased, the amount of oil supplied from D _Mt is plotted on the vertical axis in FIG. 7. As a result, D
_Mt /D _T becomes 1 or more, that is, when the minimum orifice diameter that determines the amount of lubricant supplied to the thrust bearing metal part is less than or equal to the lubricant passage diameter supplied to the radial bearing metal part on the turbine side or compressor side. It can be seen that the amount of oil supplied to _Mt begins to increase. Here, as an example, the lubricating oil passages to the radial bearing metal parts on both the turbine side and the compressor side are connected to D _Mt /
When D _T =D _Mc /D _T =1.5, the area ratio relationship is shown in 30 in Figure 8, and the lubricating oil amount relationship is shown in 32 in Figure 9.
Shown below. In addition, the lubricating oil passage to the radial bearing metal part on the turbine side is made larger than that on the compressor side, and the relationship of D _Mt /D _T >D _Mc /D _T >1 is similarly set as 31 in Fig. 8. It is shown at 33 in FIG.

Consider FIG. 9 for each characteristic 30, 31 in FIG. Consider a characteristic 32 in which the amount of lubricating oil in the thrust bearing is close to the minimum oil amount. A minimum restriction is introduced in the thrust bearing lubricating oil passage to reduce the amount of oil. As a result, since the oil pump discharge pressure is constant, the resistance of the entire lubricating oil passage system increases, so the turbo inlet oil pressure increases compared to the conventional one. As a result, the amount of oil supplied from P, Mt, and Mc increases. Figure 9 shows the total lubricating oil amount (Q
It expresses the ratio divided by the total amount of oil ( _P , Q _Mt , Q _Mc , Q _T ).

Since the amount of piston ring cooling oil is large overall, and the amount of radial bearing metal lubricating oil is small, the rate of increase exhibits characteristics as shown in FIG. Next, consider the situation when the radial bearing metal lubricating oil supply passage on the turbine side is made larger than that on the compressor side. The increase in oil amount on the turbine side is greater than on the compressor side, and everything else is the same as described above.

By taking the above measures, the amount of lubricating oil in the turbine-side radial bearing metal was increased and durability was improved.

According to the present invention, the amount of lubricating oil in the metal part of the radial bearing on the turbine side can be increased, so the cooling effect of the metal part is increased, and at the same time, the generated carbon powder is also flushed out, reducing metal wear and improving turbo charger performance. It has the effect of improving durability.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional supercharger, Figures 2 to 5
The figure is a graph of experimental results, FIG. 6 is a sectional view of a supercharger according to the present invention, and FIGS. 7 to 9 are graphs of experimental results. 1...Center housing lubricating oil supply inlet, 2
...Lubricating oil passage for piston ring cooling, 3...
Turbine side radial bearing metal lubricating oil passage, 4...
...Radial bearing metal lubricating oil passage on compressor side, 5...Thrust bearing metal lubricating oil passage, 6...
...A member with an aperture.

Claims (1)

[Scope of Claims] 1. A turbine rotationally driven by exhaust gas discharged from an engine, a compressor fixed to the rotating shaft of the turbine and rotating within the intake passage of the engine to supercharge intake air, and the rotating shaft a turbine-side radial bearing provided on the turbine side of the rotating shaft to support the compressor; a compressor-side radial bearing provided on the compressor side of the rotating shaft; and the compressor-side radial bearing and the compressor to support movement of the rotating shaft in the thrust direction. bearing means comprising a thrust bearing provided between the bearings; a sealing means comprising a piston ring for preventing lubricating oil supplied to the turbine-side radial bearing from leaking into the turbine; In the device having a lubricating oil supply passage means for supplying a predetermined lubricating oil to a piston ring cooling part provided on the outer periphery of the sealing means, each part of the lubricating oil supply passage means has a passage area of:
A supercharger characterized in that the passage area of each part is set so that the supply passage area to the piston ring cooling part<the supply passage area to the thrust bearing<the supply passage area to each of the radial bearings. 2. The supercharger according to claim 1, wherein the area of the lubricating oil supply passage to each of the radial bearings is set such that the compressor side is smaller than the turbine side.