JPH05280366A - Oil seal construction for turbocharger - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to an oil seal structure for a turbocharger, which can sufficiently maintain airtightness of a bearing portion of a turbine shaft with respect to a compressor portion and can reduce sliding resistance at the seal portion. It aims at providing the oil seal structure of. [Structure] A ring seal 7 is provided on the outer periphery of a collar 6 fitted to a turbine shaft 2 so as to be in sliding contact with the inner peripheral surface of an outer retainer 5, and a lip seal 10 is provided on the bearing side from the ring seal 7. Ring seal 7 and lip seal 10
A space 11 between and is connected to the compressor chamber by a communication passage 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbocharger installed in an automobile or the like, and more particularly to an oil seal structure on the compressor side thereof.

[0002]

2. Description of the Related Art In recent years, some internal combustion engines used in automobiles and the like are equipped with turbochargers, superchargers, or other superchargers to increase their output, and the structure of the supercharger itself. Also, various ideas have been made to improve the performance.

As is well known, the turbocharger drives a turbine by exhaust energy and transmits this rotational force to a compressor via a turbine shaft to supercharge intake air. Lubricating oil is naturally supplied to the bearing, and after lubrication of the turbine shaft, it collects at the oil outlet provided in the lower part of the main housing and is finally returned to the oil pan of the engine. It has become.

However, due to the operating conditions of the turbocharger, the pressure difference between the compressor side and the main housing side, etc., some of the lubricating oil supplied to the lubrication section may leak to the compressor side, resulting in intake air. There is a problem of polluting the oil or increasing the consumption of lubricating oil.

To address this problem, for example, as shown in FIG. 6, a seal device (a spring 65, a seal ring 66) is provided outside a collar 64 interposed between a seat ring 62 of a turbine shaft 61 and a compressor impeller 63. , Driven ring
67) is provided, and further, a piston ring 69 that contacts the inner circumference of the retainer 68 is provided on the collar 64 portion on the compressor side of the sealing device, and the sealing function is doubled. A mechanism has been proposed in which the pressure difference is reduced to reduce the surface contact force of the sealing end face in the sealing device, and to improve the durability and sealing performance in this portion (see Japanese Patent Laid-Open No. 58-101222). ).

[0006]

In the above-mentioned conventional sealing mechanism, another space is formed between the sealing device and the compressor chamber, and the pressure in this space located on the compressor side of the driven ring is controlled. I tried to make it as small as possible than the pressure in the compressor chamber,
To this end, it is necessary to further improve the airtightness of the piston ring located at the boundary between this space and the compressor chamber, so that the sliding resistance with respect to the retainer increases and the turbine rotation in the low speed region of the turbocharger is increased. Lower,
There is a delay in rising.

In view of the above problems, the present invention provides an oil seal structure for a turbocharger that can sufficiently maintain the airtightness of the bearing portion of the turbine shaft with respect to the compressor portion and reduce the sliding resistance at this seal portion. To aim.

[0008]

In order to achieve the above object, according to the present invention, it is provided between a compressor chamber of a turbocharger and a turbine shaft bearing portion to prevent oil leakage from the bearing portion to the compressor chamber. In the oil seal structure, the outer periphery of the collar that is fitted to the turbine shaft portion located between the compressor impeller and the bearing portion is provided with a ring seal that slidably contacts the outer peripheral surface of the retainer, A ring-shaped lip seal, which is in contact with the outer peripheral surface of the collar with its end surface on the bearing portion side, is provided on the bearing portion side of the ring seal, and the space between the ring seal and the lip seal is communicated with the compressor chamber. An oil seal structure for a turbocharger is provided.

[0009]

[Function] By communicating the space between the ring seal and the lip seal into the compressor chamber, the pressure in the compressor chamber is also introduced into this space, and the pressure difference before and after the ring seal can be eliminated. As a result, the space is lubricated. Even if oil enters, it will not flow into the compressor chamber. Also, since the end face of the lip seal on the bearing side is in contact with the outer peripheral surface of the collar, the compressor chamber end pressure is applied to the end face of the lip seal on the compressor side, so that airtightness can be maintained and the lip seal structure causes Therefore, the contact surface pressure can be reduced.

[0010]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a partial cross section of a turbocharger having an oil seal structure according to the present invention. In the figure, 1 is a compressor impeller, 2 is a turbine shaft, 3 is a thrust bearing, 4 is a color thrust, and 5
Show the retainers respectively. Also, color thrust 4
A collar (sleeve) 6 is fitted to the turbine shaft 2 between the compressor impeller 1 and the compressor impeller 1.

FIG. 2 is an enlarged view of portion A in FIG. As is clear from this figure, according to the present embodiment, as the oil seal structure, the collar 6 has the groove 6a along the outer periphery thereof.
The ring seal 7 is mounted in the groove 6a so as to contact the inner peripheral surface 5a of the retainer 5. Furthermore,
Another groove 8 is formed on the outer periphery of the collar 6 on the bearing portion side (or collar thrust side) of the ring seal mounting portion.
The side surface 8a of the groove 8 on the collar thrust side is tapered with respect to the turbine shaft axis 2A.

An annular recess 5a is formed on the side surface of the retainer 5 on the side of the collar thrust, and according to the present embodiment, a stepped cylindrical plate 9 is press-fitted into this recess 5a. Further, a donut disk-shaped lip seal 10 is fixed to the end surface of the plate 9 on the color thrust side by using a joining means such as an adhesive. The plate 9 is preferably made of aluminum or a resin material, and the lip seal 10 is preferably an ordinary packing rubber, resin or stainless thin plate. The lip seal 10 for the plate 9 is preferably used. As for the mounting method, the outer peripheral portion of the lip seal 10 may be cast around the plate 9 to be integrally formed. When attaching the plate 9 to the retainer 5 back and forth, the outer peripheral edge portion 9a of the plate 9 is caulked by a part of the retainer 5, or both are connected by a bolt or the like to attach the plate. You may make sure.

As shown in FIG. 2, the lip seal 10 mounted on the plate 9 as described above has its tip (the inner portion of the donut) engaged with the groove 8 described above, and the tip of the lip seal 10 is the bearing. End face 10 facing the part side (or color thrust side)
a contacts the tapered side surface 8a of the groove 8 and is positioned so as to seal at this portion. In addition, this lip seal
Regarding the contact form of 10 with the collar 6 (specifically, the groove 8 formed in the collar 6), as shown in FIGS. 3 (A) and 3 (B), the taper (θ) is formed on the sealing surface.
Alternatively, it is better to have a curvature (R) so that the seal area can be increased as much as possible.

FIG. 4 shows the retainer 5 with the plate 9 described above.
It is an expanded sectional view of a single body. As is clear from FIGS. 1 and 4, according to the present embodiment, the retainer 5 extends substantially parallel to the turbine shaft axis 2A from the end surface 5b on the compressor chamber side toward the lip seal side, and the ring seal 7 A communication passage 12 that opens in a space 11 (see FIG. 2) sandwiched between the lip seals 10 is formed. The communication passage 12 is a so-called pressure introduction hole for guiding the pressure in the compressor chamber to the space 11, and by this, the pressure difference before and after the ring seal 7 can be almost eliminated during turbocharger operation. As a result, the tendency of the lubricating oil to move due to the pressure difference between the front and rear spaces of the ring seal 7 is weakened, and the oil sealability at the ring seal 7 part is improved. Further, due to this communication, during normal operation of the turbocharger, the positive pressure in the compressor chamber is also introduced into the space 11, so the contact surface pressure of the lip seal 10 against the groove 8 increases, and the oil sealability and airtightness at this portion are increased. Therefore, the contact surface pressure of the lip seal can be minimized at the time of assembly (reduction of sliding resistance). In addition, the communication passage 12 for this retainer 5
With respect to the formation of, the retainer 5 is preferably formed at the lowest portion as shown in FIG. This is because if a slight amount of lubricating oil gets over the lip seal 10 and enters the space 11, the lubricating oil can be immediately discharged to the compressor side.
This is to prevent the communication passage 12 from being blocked due to an increase in the lubricating oil inside 11.

Regarding the size (cross-sectional area) of the communication passage 12, it is preferable that the phase of the pulsating pressure from the compressor chamber be relatively equal to each other, similarly to the orifice area of the ring seal 7. In this case, if the side clearance between the ring seal 7 and the groove 6a is L, the collar 6 is
When the outer diameter of is equal to d (FIG. 2), the orifice area of the ring seal portion is approximately πdL / 2. Therefore, if the diameter of the communication passage 12 is D,

[0017]

[Equation 1]

It is preferable that the relationship of
Is

[0019]

[Equation 2]

It is preferable to set so that

FIG. 5 shows another embodiment which is slightly different from the above-mentioned opening form of the communication passage 12 into the space 11. This is because the rear area of the compressor impeller 1 has a large negative pressure due to a sudden deceleration of the engine during high-speed operation or clogging of the intake system such as an air cleaner (not shown). At this time, a negative pressure is introduced into the space 11 via the communication passage 12, and the tip of the lip seal 10 is separated from the side surface 8a of the groove 8 to prevent the lubricating oil from flowing into the space 11 from this portion. Is provided. That is, in such a case, the lip seal 20 is caused by the negative pressure introduced into the communication passage 22 as shown in the drawing.
Part (valve part) 20a of the valve swings, and the opening 22a of the communication passage 22 is opened.
Is closed, and the communication between the space on the compressor chamber side and the space 11 is cut off. As a result, separation of the lip seal 20 from the groove 8 (FIG. 2) is prevented, and the inflow of lubricating oil is also blocked. Even in the present embodiment, normally,
The valve portion 20a has an opening 22a as shown by a dotted line in the drawing.
And the space 11 and the compressor chamber can communicate with each other.

The oil seal structure of the present invention has been described above based on various embodiments. In addition to the above-mentioned oil seal effect, positive pressure is introduced into the space 11 through the communication passage 12, and the lip seal 10 is By increasing the seal pressure, it is possible to prevent the supercharged air of the turbocharger from flowing into the bearing housing (not shown), and to reduce blow-by gas.

[0023]

As described above, according to the present invention, since the space between the ring seal and the lip seal communicates with the compressor chamber, the pressure difference before and after the ring seal can be eliminated, and the space above Even if lubricating oil enters, it becomes difficult for it to flow into the compressor chamber. Also, since the end face of the lip seal on the bearing side is in contact with the outer peripheral surface of the collar, the compressor chamber end pressure is applied to the end face of the lip seal on the compressor side, so that airtightness can be maintained and the lip seal structure causes Therefore, the contact surface pressure can be reduced.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a turbocharger having an oil seal structure of the present invention.

FIG. 2 is an enlarged view of a portion A shown in FIG.

FIG. 3 shows a collar contact form of a lip seal according to an embodiment of the present invention, in which (A) the groove side surface is formed in a tapered shape
(B) is a figure which shows each Example formed with a curvature, respectively.

FIG. 4 is a partial cross-sectional view showing only a retainer unit of the present embodiment with a plate attached.

5 is a partially enlarged view of the lower part of the retainer for explaining another embodiment different from the communication passage opening form shown in FIG. 4. FIG.

FIG. 6 is a partial cross-sectional view of a turbocharger showing a conventional oil seal structure.

[Explanation of symbols]

 1 ... Compressor impeller 2 ... Turbine shaft 5 ... Retainer 6 ... Collar 7 ... Ring seal 10, 20 ... Lip seal 11 ... Space 12, 22 ... Communication passage

Claims (1)

[Claims] 1. An oil seal structure provided between a compressor chamber of a turbocharger and a turbine shaft bearing portion for preventing oil leakage from the bearing portion to the compressor chamber, wherein the compressor impeller and the bearing portion are connected to each other. A ring seal that is slidably in contact with the outer peripheral surface of the retainer is provided on the outer periphery of the collar that is fitted to the turbine shaft portion that is located between the collar and the end portion on the bearing portion side that is closer to the bearing portion than the ring seal. An oil seal structure for a turbocharger, characterized in that a ring-shaped lip seal which is in circumferential contact with the outer peripheral surface of the collar is provided, and a space between the ring seal and the lip seal is communicated with the compressor chamber.