JPH05248253A - Waste gate valve for turbocharger - Google Patents

Abstract

PURPOSE:To smoothly turn a valve shaft with a small leakage amount of exhaust gas from the valve shaft. CONSTITUTION:A valve 5 is connected to an arm 6 by a shaft 7. A base end of the arm 6 is welded to one end of a valve shaft 8. A bearing 9 is fixed to a turbine housing 2 to provide a step difference in the internal periphery in a lower end part of this bearing, and between a shoulder 9b of this bearing and an end surface 6c of the arm 6, a seal ring 13 of small diameter and a seal ring 14 of large diameter are arranged by each two sheets in an axial line direction to be overlapped together with each other. Both the seal rings 13, 14 are made of ceramics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastegate valve for a turbocharger in an internal combustion engine.

[0002]

2. Description of the Related Art A turbocharger that pressurizes the air supplied to an internal combustion engine by the action of a compressor driven by a turbine rotated by the exhaust gas of the internal combustion engine, and a part of the exhaust gas flowing into the turbine is wastegate. It is well known to control the rotation of the turbine to control the compressor discharge pressure by opening and releasing the valve, and an example of such a system is shown in FIGS.

2 is a turbine housing, 3 is a turbine,
Reference numeral 4 is a bypass port for bypassing exhaust gas, 5 is a valve, 6 is an arm formed of a stainless plate, and the valve 5 is connected to its movable end via a shaft 7.

A valve shaft 8 made of heat-resistant steel is welded to the other end of the arm 6 and is loosely inserted into a bearing 9 made of SUS sintered material which is press-fitted into the turbine housing 2 (FIG. 4). A lever 10 is press-fitted and connected to one end of the valve shaft 8, and the other end is connected to a wastegate actuator that opens the valve 5 and controls the rotation of the turbine.

The valve shaft 8 is in the shape of a round bar, and the arm 6 is shown in FIGS.
As shown in detail in FIG. 3, a metal plate is wound around one end of the valve shaft 8 only once, and the arm 6 is welded to the valve shaft 8 at the hole 6a opened in the plate of the arm and integrated. is there.

Except for the portion of the arm 6 which is wound around the valve shaft 8, the arms 6 are overlapped with each other as shown in FIG. 5, and are spot-welded to each other at four points 6b in FIG. And valve 5
Is connected to the arm 6 by loosely fitting the shaft 7 crimped to the valve 5 into the hole of the double-armed portion of the arm 6 (FIG. 5). The valve 5, the arm 6 shown in FIG.
The assembly of the shaft 7 and the valve shaft 8 is called a valve sub-assembly.

The clearance between the valve shaft 8 and the bearing 9 is prevented from squeaking due to thermal deformation caused by a large change in temperature.
There is a relatively large clearance (Fig. 4).

[0008]

SUMMARY OF THE INVENTION In the above conventional technique,
Exhaust gas passes through the clearance between the valve shaft 8 and the bearing 9 as shown in FIG.
Exhaust gas leaks from the turbine chamber 11 to the turbine chamber 12 outside is prevented by pressing the end face 6c of the arm 6 against the end face 9a of the bearing 9 by the pressure difference inside and outside the turbine chamber. It was

However, there has been a problem that the complete gas sealing function expected as a result of vibration of an automobile or an internal combustion engine cannot be obtained. Therefore, an object of the present invention is to provide a wastegate valve for a turbocharger capable of reducing the amount of exhaust gas leaking from the turbine chamber to the outside of the turbine chamber through such clearance.

[0010]

In order to achieve the above object, the turbocharger wastegate valve according to the present invention is a wastegate valve for controlling a compressor discharge pressure, which comprises a valve shaft (8) and a bearing (9). Small-diameter ceramic seal ring (13) that fits in the outer diameter of the valve shaft (8)
And a large-diameter ceramic seal ring (14) fitted into the inner diameter of the bearing (9) are arranged adjacent to each other in the axial direction.

The seal rings (13), (14) are preferably provided at one end of the axis (9), particularly at the end facing the arm (6) connecting the valve (5).
Further, a step portion (8b) provided at an end of the valve shaft (8) far from the arm (6) and a step portion (9c) provided on the bearing (9) facing the step portion (8b). Between the seal ring (1
3) (14) may be provided.

[0012]

Since large and small seal rings are mounted so as to overlap each other in the axial direction, the leak passage of exhaust gas is lengthened by winding, and the leak amount is reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first embodiment of FIG. 1, 5 is a valve, 6 is an arm, 7 is a shaft, and 8 is a valve shaft, which constitute the same valve sub-assembly as in the prior art. 2 is a turbine housing, 9 is press-fitted into the turbine housing 8, and a step is provided on the inner periphery of the lower end of the figure, and its shoulder 9b and arm 6
Two small-diameter seal rings 13 and two large-diameter seal rings 14 are alternately overlapped with the end face 6c of the above and are arranged adjacent to each other in the axial direction.

These seal rings use ceramics such as silicon carbide and silicon nitride, which have good wear resistance at high temperatures and have a low friction coefficient. Small diameter seal ring 13
Has an inner diameter fitted to the outer diameter of the valve shaft 8 with a small clearance, and a large-diameter seal ring 14 has an outer diameter fitted to (the large-diameter portion of) the bearing 9 with a small clearance. ..

Reference numeral 10 is a lever press-fitted to one end of the valve shaft 8. FIG. 2 shows a valve shaft 8 and a bearing 9 according to a second embodiment of the present invention.
The position of the ceramic seal ring provided between the two is different from that of the first embodiment, and is arranged at the ends of the valve shaft 8 and the bearing 9 on the side closer to the lever 10.

That is, the valve shaft 8 has a small-diameter portion 8a formed at the upper end in FIG.
b is formed. The bearing 9 is formed with a step portion 9c facing the step portion 8b of the valve shaft 8, and the inner circumference of the step portion is formed to have a small diameter facing the outer circumference of the small diameter portion 8a of the valve shaft 8.

As in the case of the first embodiment, the seal rings 13 and 14 are alternately superposed and arranged adjacent to each other in the axial direction. In the above-described embodiment, the differential pressure between the turbine chamber 11 and the turbine chamber 12 is 2 kgf / cm ² , and the exhaust gas leakage amount is 0.07 g / s, which is compared with the leakage amount of 0.97 g / s in the conventional technique. Has been reduced to about 7%.

[0018]

Since the wastegate valve for a turbocharger of the present invention is constructed as described above, the alternately-sealed large-diameter and small-diameter ceramic seal rings block the leakage of exhaust gas, and the valve shaft is Turn lightly,
It is possible to realize a wastegate valve that has high wear resistance and high durability even at high temperatures.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a first embodiment of the present invention.

FIG. 2 is a sectional view of an essential part of a second embodiment of the present invention.

FIG. 3 is an overall schematic view of a turbocharger with a part cut away.

FIG. 4 is a cross-sectional view taken along line 1-1 of FIG.

5 is a plan view of the prior art valve subassembly of FIG.

[Explanation of symbols]

 5 valve 6 arm 8 valve shaft 8b step 9 bearing 9c step 13 and 14 seal ring

Claims (3)

[Claims] 1. In a wastegate valve for controlling compressor discharge pressure, a small-diameter ceramic seal ring fitted between the valve shaft and the bearing to the outer diameter of the valve shaft and a large diameter fitted to the inner diameter of the bearing. A wastegate valve for a turbocharger in which the ceramic seal ring and the ceramic seal ring are arranged adjacent to each other in the axial direction. 2. The waste gate valve for a turbocharger according to claim 1, wherein the seal ring is provided at one end of the bearing, particularly at the end opposite to the arm connecting the valves. 3. The turbocharger according to claim 1, wherein a seal ring is arranged between a step portion provided at an end portion of the valve shaft farther from the arm and a step portion provided on the bearing facing the step portion. Wastegate valve for charger.