Improvement of Wear Resistance of Waist Gate Valve

Abstract

In the technical field of wastegate valves comprising a functional assembly of a body member (20) and an actuatable member (30), measures have been proposed to limit the axial wear of the body member (20) and the actuatable member (30) relative to one another as a result of engine vibrations and pulsations. One of the measures includes a design of the wastegate valve in which at least one of the surfaces (24, 33) of the body member (20) and the actuatable member (30) facing each other in the axial direction (A) of the wastegate valve comprises at least one raised portion (26, 35) defined by at least one recessed portion (27, 36) at least in a tangential direction (T) about the axial direction (A). In this way, one or more spaces are obtained for receiving small wear particles from the interface between the body member (20) and the actuatable member (30).

Description

Technical Field

[0001] First, the present invention relates to a wastegate valve comprising a functional assembly of a body member and an operable member, the body member having a seal portion configured to be placed on a seat for the wastegate valve in the closed position of the wastegate valve, and the operable member providing an engagement region of the functional assembly, thereby enabling setting of the position of the wastegate valve through operation of the operable member.

[0002] Second, the present invention relates to a wastegate system of a turbocharger including a turbine and a compressor, and an exhaust gas inlet, the wastegate system comprising a bypass duct that bypasses the turbine downstream of the exhaust gas inlet, the bypass duct being openable and closable via the wastegate valve described above.

[0003] Third, the present invention relates to a turbocharger provided with the wastegate system described above.

Background Art

[0004] A well-known example of the field to which the wastegate valve is applied is the field of exhaust gas turbochargers. In an actual embodiment of a turbocharger that compresses intake air for an engine such as an internal combustion engine, a wastegate valve is applied to prevent the supercharging pressure of the intake air from rising excessively due to the increased pressure of the exhaust gas. For this reason, the wastegate valve is configured to limit the energy of the exhaust gas supplied to the turbine rotor of the turbocharger by opening and closing an exhaust gas bypass passage that directly bypasses a part of the inflowing exhaust gas to the exhaust gas outlet passage.

[0005] A waist gate valve includes a functional assembly of a body member and an actuatable member. The body member has a seal portion configured to be placed on a seat for the waist gate valve in a closed position of the waist gate valve. The actuatable member provides an engagement region of the functional assembly, thereby enabling the setting of the position of the waist gate valve through the operation of the actuatable member. An embodiment of a waist gate valve is known in this regard. It should be noted that one of a number of examples of known waist gate valves is found in International Publication No. WO 2013 / 098884. In particular, International Publication No. WO 2013 / 098884 discloses a waist gate valve comprising: a) a valve body for opening and closing an exhaust gas bypass passage that extracts a part of the exhaust gas flow from the inlet side of the exhaust gas passage of a turbine housing and supplies it to an exhaust gas outlet passage; b) a valve shaft standing upright from the valve body; c) an operation lever having an insertion hole formed therein with the valve shaft loosely inserted at one end and a rotational force applied at the other end; d) a support plate provided at one end of the valve shaft on the opposite side of the other end inserted through the insertion hole; and e) a vibration damping member provided in the axial direction of the valve shaft between the support plate and the operation lever for suppressing the vibration of the valve body. The vibration of the valve body occurs in response to the vibration and pulsation of the engine. Based on the vibration suppression means, the sealing performance of the waist gate valve known from International Publication No. WO 2013 / 098884 is improved and the noise is also reduced.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the context of the present invention, it is recognized that engine vibrations and pulsations cause the body member and the actuatable member of the wastegate valve to move relative to each other. This movement is very small, but it results in axial wear of the wastegate valve, based on which the durability and ultimately the functionality of the wastegate valve are impaired.

Means for Solving the Problem

[0008] In view of this, an object of the present invention is to reduce wear in a wastegate valve of a type having a functional assembly of a body member and an actuatable member. Generally speaking, an object of the present invention is to reduce the extent to which engine vibrations and pulsations affect the durability and functionality of the wastegate valve.

[0009] Aspects of the present invention are set forth in the appended independent and dependent claims. Features from the dependent claims can be combined with features from the respective independent claims as required, and are not merely those explicitly recited in the claims and explained in the following description.

[0010] The present invention provides a wastegate valve having a functional assembly of a body member and an actuatable member, said body The material is , said wastegate val of the having a seal portion configured to be seated on a seat for the wastegate val of the in a closed position, said actuatable mem upper part ber, said functional assemb of the ly providing an engagement region, whereby said actuatable mem material is ber is configured to enable setting of the position of the wastegate val of the ve through operation, said wastegate val material of the ve having at least one, on at least one of said body of the member and said actuatable mem of the ber facing each other in the axial dir direction ection, a surface that is at least tangential to the circumference around said axial dir material and ection. material of the face surface of the ection around which at least one of said body direction of the member and said actuatable memdirection at least one recess part at least one raised portion defined thereby part is is provided , the body member includes a horn-shaped element configured to extend through the seat for the waste gate valve at the closed position of the waste gate valve, the seal portion of the body member is disposed as a rim on the horn-shaped element, the horn-shaped element is at least partially hollow, the actuatable member is at least partially received within the horn-shaped element, the horn-shaped element is cup-shaped and has a central protrusion extending in the axial direction from the bottom surface, the actuatable member has a central hole into which the central protrusion is inserted, at least one surface of the body member is formed as the bottom surface of the horn-shaped element, and at least one surface of the actuatable member is formed as the top surface located within the horn-shaped element and having the central hole formed therein thereby.

[0011] From the above general definition of the waist gate valve according to the present invention, the present invention provides a configuration in which at least one of the surfaces of the body member and the operable member facing each other in the axial direction of the waist gate valve has at least one raised portion defined by at least one concave portion at least in the tangential direction around the axial direction. Conventionally, the surface has a smooth appearance, but according to the present invention, at least one of the surfaces is provided with at least one raised portion and at least one concave portion. According to the insight of the present invention, when small particles are separated from at least one of the body member and the operable member under the influence of the relative movement between the body member and the operable member and the wear effect on the related surface, these small particles can be received in at least one concave portion, and as a result, it is achieved that the influence of the presence of the particles on the configuration of the waist gate valve can be avoided. Furthermore, in such a case, it can be advantageous if the outer surface of the actuatable member and the position of the actuatable member within the body member are configured to achieve an enlarged contact area with the inner surface of the body member when changing from the initial factory shipping position to an assumed position following wear expected during the initial use period of the waste gate valve. In other words, in such a case, it can be advantageous if the outer surface of the actuatable member and the inner surface of the body member are designed to wear against each other during the initial use period of the waste gate valve, thereby achieving a closer bond with each other and obtaining greater resistance to engine vibration and pulsation. This can be achieved in various ways, including a) providing both the outer surface of the actuatable member and the inner surface of the body member with a generally tapered appearance in the axial direction when viewed from the seal portion of the body member to the free end of the horn-shaped element of the body member, and b) providing the outer surface of the actuatable member with a generally convex spherical appearance and the inner surface of the body member with a generally concave spherical appearance

[0012] In a practical embodiment of the waist gate valve according to the present invention, at least one concave portion of at least one of the surfaces of the body member and the operable member facing each other in the axial direction extends substantially in the radial direction with respect to the axial direction. It should be further noted that with respect to at least one concave portion, at least one concave portion may have a substantially linear appearance or a substantially wavy appearance. In either case, it is advantageous if the width of at least one concave portion is small compared to the dimension of at least one raised portion in the tangential direction, that is, if at least one concave portion is narrow, in order to still have a sufficiently large contact area between the body member and the operable member.

[0013] In the context of the present invention, the number of raised portions and recessed portions can be freely selected. Both the raised portion and the recessed portion may be one, but at least two raised portions and at least two recessed portions may be provided on at least one of the surfaces of the main body member and the operable member that face each other in the axial direction. The raised portions and the recessed portions may be provided in any suitable pattern.

[0014] As suggested above, the present invention relates to a type of waist gate valve comprising a functional assembly of a main body member and an operable member. The main body member and the operable member may be of any suitable design. As is known in the field of waist gate valves, it is practical that a lever arm rotatably arranged about a lever axis outside the waist gate valve is connected to the operable member.

[0016] According to one aspect of the present invention, the design of the waist gate valve conforms to specific criteria aimed at obtaining advantageous wear behavior at the interface between the body member and the actuable member. One practical criterion can include the ratio between a) the dimensions of a region extending perpendicular to the axial direction and defined by the inner circumference of the seal portion of the body member, and b) the dimensions of a region extending perpendicular to the axial direction and defined by the outer circumference of a region where the body member and the actuable member are intended to contact each other at an inner position of the horn-shaped element after initial use of the waist gate valve. The insight of the present invention is that it is advantageous when this ratio is at most 3.5, which is related to maximizing the protruding axial contact surface for wear reduction against the axial contact at a low level within the horn-shaped element in order to guarantee the proper sealing function of the waist gate valve throughout its lifespan. The indication of the region where the body member and the actuable member are intended to contact each other after initial use of the waist gate valve should be understood in the context of the wear expected during the initial use period of the waist gate valve as described above. In practice, it is possible to increase the region where the body member and the actuable member contact each other inside the horn-shaped element, and what is considered in the definition of the ratio is the size of this region after the initial use period and the related initial wear effect of the body member and the actuable member relative to each other. Indicating a low level of axial contact should be understood in the context of the movement direction of the waist gate valve to take the closed position.

[0017] Further features and advantages of the present invention will become apparent from the description of the present invention by way of exemplary and non-limiting embodiments of the waist gate valve.

[0018] A person skilled in the art will understand that the described embodiments of the waist gate valve according to the present invention are merely exemplary in nature and should never be construed as limiting the scope of protection defined in the claims. A person skilled in the art will understand that alternative and equivalent embodiments of the waist gate valve can be devised and implemented without departing from the scope of protection of the present invention.

[0019] Refer to the figures on the attached drawing sheet. The figures are essentially schematic and are therefore not necessarily drawn to scale. Further, the same reference numbers indicate the same or similar parts.

Brief Description of the Drawings

[0020]

Figure 1

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Mode for Carrying Out the Invention

[0021] The figure shows an advantageous practical embodiment of the wastegate valve 10 according to the present invention. The wastegate valve 10 comprises a functional assembly 11 of a body member 20 and an actuatable member 30, and the wastegate valve 10 is intended to be used in a wastegate system 110 of a turbocharger 100 including a turbine 101 and a compressor 102. The wastegate valve 10 according to the present invention is designed such that the influence of axial wear at the interface between the body member 20 and the actuatable member 30 as a result of engine vibration and pulsation is limited. As a result, a durable wastegate valve 10 can be obtained that can implement the intended function of controlling the degree to which exhaust gas can flow into the bypass duct 111 of the wastegate system 110 over the entire life of the wastegate valve 10. Details related to this point will become apparent from the following. Generally speaking, the surface structure of at least one of the surfaces of the body member 20 and the actuatable member 30 that face each other in the axial direction A of the wastegate valve 10 is adjusted to provide one or more spaces for receiving small wear particles. During the manufacturing process of the wastegate valve 10, the surface structure may be realized in any suitable manner, for example by debossing technology or casting technology followed by machining. Further, in the context of an embodiment in which the body member comprises a horn-shaped element and the level of axial contact is low within the horn-shaped element, it is advantageous when axial contact can occur over a region where it is relatively large.

[0022] Referring to FIG. 1, a brief description of the general configuration of the turbocharger 100 and the wastegate system 110 is provided. The turbine 101 of the turbocharger 100 is configured to rotate by the exhaust gas of an engine (not shown), and the compressor 102 of the turbocharger 100 is configured to be driven by the turbine 101 to compress the intake air of the engine. The turbocharger 100 further includes an exhaust gas channel 103 and an exhaust gas inlet 104, and the exhaust gas received from the engine is transported through the exhaust gas channel 103 toward the turbine 101 during the operation of the turbocharger 100. In the wastegate system 110, the wastegate valve 10 serves to open and close a bypass duct 111 to the exhaust gas channel 103. The bypass duct 111 is arranged to bypass the turbine 101 so that the exhaust gas branched from the exhaust gas channel 103 bypasses the turbine 101 and is guided to the downstream side of the turbine 101.

[0023] Referring to FIGS. 2, 3 and 4, it should be noted that the body member 20 of the wastegate valve 10 has a seal portion 21 configured to be placed on a seat portion 105 for the wastegate valve 10 in the closed position of the wastegate valve 10 as shown in FIG. 3. The seat portion 105 is present at an appropriate position on the turbine housing 120 of the turbocharger 100, and the appropriate position allows all of the exhaust gas entering the turbocharger 100 from the engine through the exhaust gas inlet 104 to flow to the turbine 101 when the wastegate valve 10 is in the closed position, and when the wastegate valve 10 is in the open position, a part of the exhaust gas entering the turbocharger 100 from the engine through the exhaust gas inlet 104 bypasses the turbine 101 through the bypass duct 111, so that as a result, all of the exhaust gas cannot reach the turbine 101. In the context of the present invention, any suitable mechanism for moving the functional assembly 11 of the body member 20 and the actuatable member 30 may be applied, and any suitable method for controlling the position of the wastegate valve 10 is possible. The actuatable member 30 is configured to provide an engagement region for the functional assembly 11, that is, a region where a mechanism for moving the functional assembly 11 can engage with the functional assembly 11, thereby enabling the setting of the position of the wastegate valve 10 through the operation of the actuatable member 30. In the illustrated example, the actuatable member 30 is rotatably arranged around a lever shaft outside the wastegate valve 10 and is actuated by a lever arm 31 coupled to the actuatable member 30.

[0024] Figures 2, 3 and 4 show a waist gate valve 10 according to a first embodiment of the present invention. The body member 20 includes a horn-shaped element 22 configured to extend through a seat portion 105 for the waist gate valve 10 at the closed position of the waist gate valve 10. It can be seen that the seal portion 21 of the body member 20 is arranged as a rim on the horn-shaped element 22. The horn-shaped element 22 is partially hollow, and the actuatable member 30 is partially accommodated within the horn-shaped element 22. In the illustrated example, the horn-shaped element 22 is generally cup-shaped and includes a central protrusion 23 extending in the axial direction A. The actuatable member 30 has a central hole 32, and the central protrusion 23 of the horn-shaped element 22 extends through the actuatable member 30 at the position of the central hole 32 of the actuatable member 30. In addition to the body member 20 and the actuatable member 30, the waist gate valve 10 includes a washer element 40 disposed on the central protrusion 23 for locking the axial position of the actuatable member 30 relative to the body member 20.

[0025] At the cup-shaped bottom position of the body member 20, the surfaces 24, 33 of the body member 20 and the actuatable member 30 face each other in the axial direction A. The interface surface of the surfaces 24, 33, hereinafter also referred to as the wear surfaces 24, 33, is an important area in the waist gate valve 10 because in this area, wear effects occur under the influence of engine vibrations and pulsations and, in some cases, other factors. This causes a relatively high degree of wear of the wear surfaces 24, 33 during the initial use period of the waist gate valve 10 until the surfaces 24, 33 so to speak become fixed to each other. The design of the waist gate valve 10 may be selected such that the initial contact area at the position of the wear surfaces 24, 33 at the time of initial factory shipment is relatively small and expands as a result of the wear process during the initial use period. In the illustrated example, both the outer surface 34 of the actuatable member 30 and the inner surface 25 of the body member 20 have a generally tapered appearance in the axial direction A when viewed from the seal portion 21 of the body member 20 to the free lowermost end of the horn-shaped element 22 of the body member 20. As a result, the actuatable member 30 can be displaced somewhat deeper into the body member 20 as a result of the initial wear effect of one member 20, 30 on the other member 20, 30.

[0026] When the waist gate valve 10 is placed from the closed position to the open position, the seal portion 21 of the main body member 20 moves away from the seat portion 105, and the horn-shaped element 22 is present at the position of the seat portion 105 and retreats at least partially through the access opening 121 that provides access from the exhaust gas channel 103 to the bypass duct 111. As long as the waist gate valve 10 is maintained in the open position, air can pass through the access opening 121. When the waist gate valve 10 is placed from the open position to the closed position, the horn-shaped element 22 is moved deeper through the access opening 121 until the seal portion 21 abuts against the seat portion 105. As a result, a sealing effect is obtained and the passage of air to the bypass duct 111 is disabled.

[0027] Figures 5, 6, 7, and 8 show some options regarding the surface structure of the wear surface 24 of the main body member 20 and / or the wear surface 33 of the actuatable member 30. Generally, the surface structure is such that at least one raised portion 26, 35 defined by at least one concave portion 27, 36 in at least the tangential direction T around the axial direction A is provided on each of the wear surfaces 24, 33. Small particles separated from at least one of the wear surfaces 24, 33 as a result of the wear effect can be received within at least one of the concave portions 27, 36 and thus can be held in a harmless position in the sense that they cannot have any effect on the configuration of the waist gate valve 10 over the entire life of the waist gate valve 10.

[0028] At least one of the concave portions 27, 36 can be provided on one or both of the wear surfaces 24, 33. As shown in FIGS. 5, 6, 7, and 8, it is advantageous if at least one of the concave portions 27, 36 extends substantially in the radial direction R with respect to the axial direction A. Further, at least one of the concave portions 27, 36 can have a substantially linear appearance as shown in FIGS. 5 and 6, or a substantially wavy appearance as shown in FIGS. 7 and 8. In the context of the present invention, the number of the concave portions 27, 36 can be freely selected. When the number is selected to be one, single raised portions 26, 35 are obtained that extend over substantially the entire wear surfaces 24, 33 in the tangential direction T. When the number is selected to be two or more, the same number of raised portions 26, 35 may be obtained. In this regard, it should be noted that FIGS. 5 and 6 relate to an option where the number of the concave portions 27, 36 is six, and FIGS. 7 and 8 relate to an option where the number of the concave portions 27, 36 is two.

[0029] FIGS. 9 and 10 show the sizes of the wear surfaces 24, 33 of the body member 20 and the actuatable member 30 that define the contact region between the body member 20 and the actuatable member 30 after the initial use of the waist gate valve 10. The wear surfaces 24, 33 are shown in a hatched manner, and the raised portions 26, 35 and the concave portions 27, 36 are not shown for clarity. In the illustrated example, the waist gate valve 10 is designed such that after the initial use of the waist gate valve 10, the dimensions of the region defined by the circumference of the contact region at the inner position of the horn-shaped element 22, which extends perpendicular to the axial direction A, are relatively large compared to the dimensions of the region defined by the inner circumference of the seal portion 21 of the body member 20, which also extends perpendicular to the axial direction A. The diameter of the first region is shown as d in FIG. 4 c and the diameter of the second region is shown as d in FIG. 4 sIt is shown as such. Note that in the illustrated example, both the first region and the second region have a circular outer periphery. This is not essential in the context of the present invention, and in fact, the first region and the second region may have any shape. Having a relatively large first region contributes to obtaining an advantageous wear behavior of the wear surfaces 24, 33 with respect to each other, and a situation where the force is concentrated only in a relatively small region is avoided. The ratio between the second region and the first region is preferably at most 3.5, in other words, the first region is preferably at most one thirty-fifth of the second region.

[0030] Figures 11, 12, and 13 show a waist gate valve 10 according to a second embodiment of the present invention. In Figure 11, a comparison is shown between the design of a waist gate valve 10 according to a second embodiment of the present invention (hereinafter also referred to as the second waist gate valve 10) and the design of a waist gate valve 10 according to a first embodiment of the present invention (hereinafter also referred to as the first waist gate valve 10). In the second waist gate valve 10, it can be seen that the body member 20 includes a disk-shaped element 28 including a seal portion 21 and a central protrusion 23. The operable member 30 is substantially ring-shaped and is disposed on the central protrusion 23 of the body member 20. Similar to the case of the first waist gate valve 10, a washer element 40 is disposed on the central protrusion 23 to lock the axial position of the operable member 30 with respect to the body member 20. Further, a lever arm 31 extends from the operable member 30.

[0031] The first significant difference between the first waist gate valve 10 and the second waist gate valve 10 is that in the case of the first waist gate valve 10, a part of the waist gate valve 10 actually extends through the access opening 121 when the waist gate valve 10 is in the closed position, while in the case of the second waist gate valve 10, nothing can pass through the access opening 121 within the waist gate valve 10. The second significant difference is that on the side of the disk-shaped element 28 opposite to the side where the body member 20 contacts the seat portion 105 when the waist gate valve 10 is in the closed position, the wear surface 33 of the actuatable member 30 faces the wear surface 24 of the body member 20.

[0032] The concept of having at least one raised portion 26, 35 defined by at least one concave portion 27, 36 in / on at least one of the wear surface 24 of the body member 20 and the wear surface 33 of the actuatable member 30 is also applicable to the second waist gate valve 10. In this regard, FIG. 14 shows an option in which at least one raised portion 26 and at least one concave portion 27 are provided on the wear surface 24 of the body member 20, and FIG. 15 shows an option in which at least one raised portion 35 and at least one concave portion 36 are provided on the wear surface 33 of the actuatable member 30.

[0033] It will be apparent to those skilled in the art that the scope of the present invention is not limited to the above examples and that various modifications and changes can be made without departing from the scope of the present invention defined by the appended claims. In particular, combinations of specific features of various aspects of the present invention can be made. One aspect of the present invention can be further advantageously enhanced by adding features described in relation to another aspect of the present invention. Although the present invention has been illustrated and described in detail in the figures and description, such illustration and description should be regarded as illustrative or exemplary only, not limiting.

[0034] The present invention is not limited to the disclosed embodiments. Variations to the disclosed embodiments can be understood and achieved by those skilled in the art when implementing the claimed invention, from a consideration of the drawings, the description, and the appended claims. In the claims, the term "comprising" does not exclude other steps or elements, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be advantageously used. Any reference signs in the claims should not be construed as limiting the scope of the invention.

[0035] Notable aspects of the present invention are summarized as follows. In the technical field of a waist gate valve 10 comprising a functional assembly 11 of a body member 20 and an operable member 30, means are proposed for limiting the axial wear of the body member 20 and the operable member 30 relative to each other as a result of engine vibrations and pulsations. One measure is that at least one of the surfaces 24, 33 of the body member 20 and the operable member 30 facing each other in the axial direction A of the waist gate valve 10 comprises at least one raised portion 26, 35 defined by at least one concave portion 27, 36 at least in the tangential direction T around the axial direction A. In this way, one or more spaces are obtained for receiving small wear particles from the interface between the body member 20 and the operable member 30, so that such particles cannot affect the configuration of the waist gate valve 10.

Explanation of Signs

[0036] 100 Turbocharger 101 Turbine 102 Compressor 103 Exhaust gas channel 104 Exhaust gas inlet 105 Seat 110 Wastegate system 111 Bypass duct 120 Turbine housing 121 Access opening 10 Waste gate valve 11 Functional assembly 20 Body member 21 Seal part 22 Horn-shaped element 23 Central protrusion 24 Wear surface 25 Inner surface 26 Raised part 27 Concave part 28 Disk-shaped element 30 Operable member 31 Lever arm 32 Central hole 33 Wear surface 34 Outer surface 35 Raised part 36 Concave part 40 Washer element d c Diameter d s Diameter A Axial direction R Radial direction T Tangential direction

Claims

1. A waist gate valve comprising a functional assembly of a body member and an operable member, wherein the body member has a seal portion configured to be placed on a seat for the waist gate valve at the closed position of the waist gate valve, and the operable member provides an engagement region of the functional assembly, thereby enabling setting of the position of the waist gate valve through operation of the operable member. At least one of the surfaces of the body member and the operable member facing each other in the axial direction of the waist gate valve is provided with at least one raised portion defined by at least one concave portion extending at least tangentially around the axial direction. The body member comprises a horn-shaped element configured to extend through the seat for the waist gate valve at the closed position of the waist gate valve, and the seal portion of the body member is arranged as a rim on the horn-shaped element. The horn-shaped element is at least partially hollow, and the operable member is at least partially received within the horn-shaped element. The horn-shaped element is cup-shaped and has a central protrusion extending in the axial direction from the bottom surface. The operable member has a central hole into which the central protrusion is inserted. The at least one surface of the body member is formed as the bottom surface of the horn-shaped element. The at least one surface of the operable member is located within the horn-shaped element and is formed as a top surface in which the central hole is formed, a waist gate valve.

2. The at least one concave portion of the at least one surface of the body member and the operable member facing each other in the axial direction extends substantially radially with respect to the axial direction, the waist gate valve according to claim 1.

3. The at least one concave portion on the at least one surface of the body member and the operable member facing each other in the axial direction has a substantially linear appearance, the waist gate valve according to claim 1 or 2.

4. The at least one concave portion on the at least one surface of the body member and the operable member facing each other in the axial direction has a substantially wavy appearance, the waist gate valve according to claim 1 or 2.

5. The width of the at least one concave portion is small as compared with the dimension of the at least one raised portion in the tangential direction, the waist gate valve according to claim 1 or 2.

6. At least two raised portions and at least two concave portions are provided on the at least one surface of the body member and the operable member facing each other in the axial direction, the waist gate valve according to claim 1 or 2.

7. The outer surface of the operable member is configured to realize an enlarged contact area with the inner surface of the body member when the position of the operable member in the body member changes from an initial factory shipment position to an assumed position following wear expected during an initial use period of the waist gate valve, the waist gate valve according to claim 1 or 2.

8. Both the outer surface of the operable member and the inner surface of the body member have a substantially tapered appearance in the axial direction when viewed from the seal portion of the body member to the free end of the horn-shaped element of the body member, the waist gate valve according to claim 7.

9. The outer surface of the operable member has a substantially convex spherical appearance, and the inner surface of the body member has a substantially concave spherical appearance, the waist gate valve according to claim 7.

10. a) the dimensions of the region extending perpendicular to the axial direction and defined by the inner circumference of the seal portion of the body member, and b) the dimensions of the region extending perpendicular to the axial direction and defined by the outer circumference of the region intended for the body member and the actuatable member to come into contact with each other at an inner position of the horn-shaped element after initial use of the wastegate valve, the ratio between which is at most 3.5, the wastegate valve according to claim 1 or 2.

11. A lever arm rotatably arranged around a lever shaft outside the wastegate valve is coupled to the actuatable member, the wastegate valve according to claim 1 or 2.

12. A wastegate system of a turbocharger including a turbine, a compressor, and an exhaust gas inlet, the wastegate system comprising a bypass duct bypassing the turbine downstream of the exhaust gas inlet, the bypass duct being openable and closable by the wastegate valve according to claim 1 or 2, the wastegate system.

13. A turbocharger comprising the wastegate system according to claim 12.

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