JPH04272430A - Waste gate valve - Google Patents

Abstract

PURPOSE:To provide a waste gate valve of a turbocharger whose durability is not partially damaged even if a valve flapper is in contact to an arm with operation. CONSTITUTION:In a waste gate valve, a valve shaft part 5 of a valve flapper 1 is pivotably fitted to a through-hole 7 formed on an end of an arm 2 with gaps 9, 11. An outer peripheral surface 5b of the valve shaft part 5 of the valve flapper 1 is tapered, while an inner peripheral surface 2c of the through-hole 7 of the arm 2 is also tapered so as to complement the tapered portion of the valve flapper 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastegate valve that is installed in a turbocharger of an internal combustion engine, and bypasses exhaust gas for supercharging control.

0002

2. Description of the Related Art A turbocharger installed in an internal combustion engine is generally provided with a wastegate valve that allows a portion of exhaust gas to bypass an exhaust turbine in order to suppress an excessive rise in boost pressure. This wastegate valve is located inside the turbine housing of a turbocharger, and usually includes a pressure-responsive actuator, a rod that transmits the driving force from the actuator, an arm that swings at the tip of the rod, and a swinging arm attached to the end of the rod. It consists of a valve flapper (valve body) that is attached.

FIG. 5 shows a valve flapper mounting portion of a general wastegate valve. That is, in this mounting method, first, the short pin 50 with a flange is inserted into the arm 51 from above, and then the tip thereof is passed through the center hole 52a of the valve flapper 52, and the short pin 50 is projected from the end surface 52b of the valve flapper 52. short pin 5
After spinning the tip portion 50a of 0, the short pin 50 and the valve flapper 5 are crimped.
2 is fixed.

However, in the above-described valve flapper fixing method, in addition to directly exposing the fixing portion between the short pin 50 and the valve flapper 52 to high-temperature exhaust gas,
When the wastegate valve is activated, it receives exhaust pressure (white arrow) from below in the figure and receives a bending moment as shown by the arrow, which may ultimately cause the valve flapper to be thermally deformed.

In order to deal with the above-mentioned problems of waste gate valves, a waste gate valve as shown in FIG. 6 has also been proposed (Japanese Utility Model Application No. 118337/1983). This wastegate valve has a valve flapper 60 consisting of a flat valve body part 60a and a valve stem part 60b extending perpendicularly to the valve body part 60a. The flapper valve shaft part 60b is inserted from below the arm 61, and the part protruding from the upper part of the arm 61 is fixed with a washer 62, etc., and the fixed part is separated from the valve flapper body part 60a to prevent high-temperature exhaust gas. The valve flapper 60 is provided with a convex portion 60c to prevent its movement from being exposed to gas, and to prevent the valve flapper 60 from being tilted more than necessary due to the flow of exhaust gas from below when the wastegate valve is operated. ing.

[0006]

[Problems to be Solved by the Invention] However, in the above-mentioned wastegate valve, the valve flapper 60 is generally designed from the viewpoint of seating performance (i.e., exhaust gas sealing performance) and ease of assembly when the wastegate valve is closed. The valve flapper 60 is mounted with a slight play (gap) 63 between the valve stem portion 60b and the through hole of the arm 61. As a result, when the valve flapper 60 is subjected to a bending moment as shown in FIG. 61a and the valve stem portion 6 of the valve flapper 60
0b comes into contact. In other words, a considerable stress is applied to the root portion of the valve flapper shaft portion 60 due to this contact and the bending moment, and the reliability of the valve flapper 60 at this portion is poor. SUMMARY OF THE INVENTION An object of the present invention is to provide a waste gate valve whose durability is not locally impaired even if the valve flapper comes into contact with an arm as the waste gate valve operates.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a valve flapper comprising a flat valve body portion and a valve stem portion extending perpendicularly to the valve body portion. In a wastegate valve, the valve stem is pivotally connected with a gap to a through hole formed at the tip of an arm that swings about the base end, and the vertical cross-sectional contour line of the valve stem is defined by the outer circumferential surface of the valve stem. It is tapered so as to be inclined with respect to the flapper axis, and the inner circumferential surface of the through hole of the arm facing the tapered outer circumferential surface of the valve stem is tapered so as to be complementary to the taper. A waste gate valve is provided, characterized in that the waste gate valve is formed in the following manner.

[0008]

[Operation] When the wastegate valve is operated, even if the valve flapper is tilted with respect to the arm, the outer peripheral surface of the valve stem will
Due to its tapered shape, the arm comes into line contact with the inner circumferential surface of the through hole, so that the concentration of load on the boundary between the valve stem and the valve body is alleviated.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described with reference to the drawings. FIG. 1 shows a longitudinal section of a wastegate valve according to the present invention, in which 1 is a valve flapper, 2 is an arm that is swung by an actuator (not shown) via a rod, and 3 is a valve flapper 1 attached to arm 2. It is a plate washer used for

As shown in the figure, the valve flapper 1 consists of a flat valve body 4 and a valve stem 5 extending perpendicularly to the valve body 1 along the valve flapper axis A.
is inserted from below in the figure into a through hole 7 formed at the tip of the arm 2, which swings around the base end 6 that is the connecting portion with the rod. Note that the planar shape of the valve body portion 4 can take any suitable shape (circular or rectangular) depending on the shape of the exhaust gas outlet (not shown).

FIG. 2 is a partially enlarged view of FIG. 1. As is clear from this figure, the valve shaft portion 5 of the valve flapper 1 has a reduced diameter in a stepped manner near its tip, and the tip edge is chamfered, creating a so-called valve flapper. A filler storage portion 8 is formed for filling the filler during installation.

On the other hand, the through hole 7 of the arm 2 is expanded in diameter in a stepped manner in the vicinity of its end surface 2a, similarly to the valve flapper valve shaft portion 5, and a housing portion for the plate washer 3 is formed. Therefore, when fixing the valve flapper 1 to the arm 2, after inserting the valve flapper 1 into the through hole 7 from below, the relative position of the valve flapper 1 with respect to the arm 2 is adjusted, for example, between the lower end surface 2b of the arm and the valve body part. This is maintained at a predetermined value by controlling the gap 9 of 4, and then the plate washer 3 is fitted into the reduced diameter portion 5a of the valve stem 5, and the lower end surface 3a of the plate washer 3 is inserted into the stepped portion of the through hole 7. portion 7a and melt the filler agent 10 into the filler agent storage portion 8 defined by the inner circumferential surface 3b of the plate washer 3 and the valve shaft reduced diameter portion 5a of the valve flapper 1,
Fix the plate washer 3 and valve flapper 1. That is, the plate washer 3 in this embodiment is provided to prevent the valve flapper 1 from falling off downward, and the plate washer 3 is not fixed to the arm 2.

[0013] including the above-mentioned plate washer joint;
The inner diameter of the through hole 7 is set to be slightly larger than the outer diameter of the valve shaft portion 5 of the valve flapper 1 at any position in the axis A direction. That is, when the valve flapper 1 and the arm 2 are connected via the plate washer 3, a gap 11 is formed between the inner circumferential surface 2c of the through hole 7 and the outer circumferential surface 5b of the valve stem portion 5. It turns out.

Furthermore, according to this embodiment, the valve flapper 1
Regarding a part of the valve stem outer circumferential surface 5b near the valve body part 4, its vertical cross-sectional contour line (the line shown in FIGS. 1 and 2) is at a predetermined angle (for example, 1 to 10 degrees). That is, specifically,
The valve stem portion 5 is formed so that its diameter gradually decreases from the connection portion with the valve body portion 4 toward the plate washer 3. Regarding the through hole 7 of the arm 2, the inner circumferential surface 2c (part) facing the tapered valve stem outer circumferential surface 5b (part) similarly has its longitudinal cross-sectional contour line the valve flapper axis. It is formed to be inclined with respect to A in the same way as the above-mentioned outer circumferential surface inclination, in other words, to be complementary to the taper of the valve stem portion 5. In this embodiment, the inner circumferential surface portion 2d of the through hole located outside the plate washer 3 is also tapered to ensure a clearance when the plate washer is tilted.

As a result, the contact form of the valve flapper 1 with the arm 2 when the wastegate valve is operated is as shown in FIG.
As shown in the figure, there is a so-called line contact between the tapered outer circumferential surface 5b of the valve stem and the inner circumferential surface 2c of the through hole, and the contact area is increased compared to conventional waste gate valves, so that the valve flapper when the waste gate valve is operated. The degree of local stress concentration on the arm 1 and the arm 2 is alleviated, and the pressure received at this portion is reduced and dispersed. Further, the tapering of the valve flapper valve shaft portion 5 results in a thicker portion compared to other portions of the valve shaft portion 5 that are not tapered, thereby further improving durability. According to this embodiment, as the inner circumferential surface of the through hole of the arm 2 and the outer circumferential surface of the valve stem of the valve flapper 1 are tapered, the relative positioning when assembling the arm and valve flapper described above is It can also be managed by changing the size of the gap 11 as the flapper moves up and down.

Although one embodiment of the present invention has been described above, in order to improve the durability of the waste gate valve, in addition to tapering the valve flapper and arm described above, it is also necessary to adjust the materials forming these components. It is preferable that sufficient consideration be given. For example, regarding valve flappers,
Some models used austenitic stainless steel, but it is also possible to use austenitic cast steel, which has high creep strength at high temperatures, and valve flappers, arms, plate washers, etc. are used to prevent gaps from changing even when temperature changes. They may all be made of the same material so that the swing angle of the valve flapper remains constant regardless of temperature changes to ensure the durability of the joint portion.

In the embodiment described above, both the valve flapper and the arm are partially tapered, but in consideration of the durability of the plate washer, the plate washer 3 is tapered as shown in FIG. 4(a). The outer circumferential surface 3c is also tapered at almost the same angle corresponding to the enlarged diameter portion of the through hole to prevent the plate washer 3 from coming into point contact with the arm 2 even if the valve flapper 1 is tilted. When the gate valve is activated, the pressure received from the arm may be reduced or dispersed. Further, as shown in FIG. 4B, the outer circumferential surface 5b of the valve flapper valve stem and the inner circumferential surface 2c of the arm through hole 7, excluding the joint portion with the plate washer 3, may all be tapered.

As explained above, according to the present invention, by tapering the outer circumferential surface of the valve stem of the valve flapper and the inner circumferential surface of the through hole of the arm, the contact area when the valve flapper is tilted increases. This reduces load concentration and improves durability. In other words, along with this improved durability, as a secondary effect,
A turbocharger equipped with this wastegate valve can achieve high supercharging pressure, resulting in improved output. In addition, reliability and durability at high exhaust temperatures can be achieved, resulting in improved fuel efficiency at high speeds.

[Brief explanation of the drawing]

1 is a partial longitudinal sectional view of a wastegate valve according to the invention; FIG.

FIG. 2 is a partially enlarged sectional view of FIG. 1;

FIG. 3 is a diagram showing a state in which the valve flapper is inclined with respect to the arm in the wastegate valve of the present invention.

4 are cross-sectional views showing two modified embodiments that further improve the durability of the embodiment shown in FIG. 1, in which (a) the outer peripheral surface of the plate washer is tapered, and (b) the plate washer FIG. 3 is a view showing an embodiment in which the outer circumferential surface of the valve flapper valve shaft and the inner circumferential surface of the arm through hole, excluding the joint portion with the valve flapper, are all tapered.

FIG. 5 is a diagram showing a state in which a valve flapper of a general conventional wastegate valve is attached.

FIG. 6 is a diagram showing the structure of a conventional wastegate valve in which a valve flapper fixing portion is disposed on the opposite side from an exhaust gas jetting portion.

[Explanation of symbols]

1...Valve flapper 2...Arm 2c...Inner peripheral surface of through hole 3...Plate washer 4...Valve body part 5...Valve stem part 5b...Valve stem outer peripheral surface 6...Proximal end 7...Through hole 9, 11...Gap A...Valve flapper axis

Claims (1)

[Claims] Claim 1: The valve stem of a valve flapper, which is composed of a flat valve body and a valve stem extending perpendicular to the valve body, is attached to the tip of an arm that swings about the base end. In a wastegate valve that is pivotally mounted with a gap in the formed through hole, the outer circumferential surface of the valve stem is tapered so that its vertical cross-sectional contour line is inclined with respect to the valve flapper axis, and the valve stem is A waste gate valve characterized in that an inner circumferential surface portion of the through hole of the arm facing the tapered outer circumferential surface portion of the arm is formed into a tapered shape so as to be complementary to the taper.