WO2021180315A1

WO2021180315A1 - Method of configuring a gas exchange valve assembly in an internal combustion piston engine and a gas exchange valve

Info

Publication number: WO2021180315A1
Application number: PCT/EP2020/056517
Authority: WO
Inventors: Sven SÖCHTING; Jyrki SUUTALA
Original assignee: Wärtsilä Finland Oy
Priority date: 2020-03-11
Filing date: 2020-03-11
Publication date: 2021-09-16
Also published as: CN115244280A; EP4118308B1; EP4118308A1; KR20220140010A

Abstract

Invention relates to a method of configuring a gas exchange valve assembly (10) in an internal combustion piston engine comprising providing a gas exchange valve (16), providing a valve seat (18), arranging an abrasive wearing overlay (28) on base material at a region of a sealing surface (26) of first one of the gas exchange valve disk (16.2) and the valve seat (18), assembling the valve seat into a gas exchange valve body, assembling the valve into the gas exchange valve body, and while running the engine, rotating the valve (16) around its longitudinal axis during its lift and/or close movements such that the sealing surface (26) of the valve detach and/or touch the valve seat in the gas exchange valve body by a movement comprising a rotational component, wherein the abrasive wearing overlay (28) machines the sealing surface (26).

Description

Method of configuring a gas exchange valve assembly in an internal combustion piston engine and a gas exchange valve

Technical field [001] The present invention relates to method of configuring a gas exchange valve assembly in an internal combustion piston engine according to the pream ble of claim 1.

[002] The present invention relates to gas exchange valve of an internal com bustion piston engine, comprising a valve stem and a valve disc at a first end of the stem, wherein the valve disc has a sealing surface.

Background art

[003] The interface of the combustion engine valve sealing surface and its seat surface are sensitive to non-conformity of the surfaces e.g. due to misalignment and shape deformation either during assembly or via distortions resulting from temperature and pressure during engine operation. The nonconformity of the sur faces may lead to insufficient sealing properties and or wear due to increased contact stress, both resulting in failure of the component requiring pre-mature engine shut down and repair. In particular the effects resulting from engine oper- ation are difficult to predict and compensate.

[004] EP0126323 A2 discloses a component for a combustion chamber of a high speed diesel engine, of the type having sliding surfaces provided with wear- protection layers which are used up during the running-in period, and to a process for obtaining such layers. The publication recognizes that for the purpose of ex- tending the life of diesel engines and the maintenance intervals thereof it is sought to encourage a correct running-in by means of the application of wear- protection layers on the sliding surfaces of the mechanical elements forming components of the engine, and in particular those forming the combustion cham ber. There is disclosed a component of a combustion chamber of a diesel engine in particular, of the type comprising at least one sliding surface coated with a wear-protection layer which can be worn away during a running-in period, said wear layer is constituted by a nitride based heat diffusion layer containing a per centage by weight of nitrogen lying between about 4% and 12%. The process for forming a wear-protection layer over a sliding surface of an element forming a component of a combustion chamber of a diesel engine, which can be worn away during the running-in period of the said engine. The layer comprises a phase of gaseous nitriding of the said surface performed with ammonia or nitrogen ionised at a temperature less than or equal to 600°C in conditions such as to obtain on the said surface the formation of a layer of nitrides substantially of 6 - type. Even if EP0126323 generally refers to a number components for a combustion cham ber of a diesel engine, the enabling disclosure of the document relates to piston rings of the engine.

[005] GB983120 A discloses a surface coating on periphery of piston rings which accelerates the wear rate until the rings are bedded-in. The piston rings according to the document having their peripheral faces covered with a bonding agent, an abrasive and a lubricant. The proposed coating is not suitable for the temperatures and contact pressures in gas exchange valve they are surface smoothing but would not remove a sufficient amount of material to create the dimensional change required. [006] Publication US7225781 B2 discloses particularly an engine valve used for opening or closing intake and exhaust paths of an automobile or a motorcycle engine. The document teaches a method for surface treating an engine valve made from titanium or titanium alloy in order to form a hardened coating having improved abrasion and impact resistances. A hardened layer is formed on the surface of the engine valve by furnishing the surface of the engine valve with oxygen as a solid solution and then forming a coating on the surface of the hard ened layer with a PVD process.

[007] An object of the invention is to provide method of configuring a gas ex change valve assembly in an internal combustion piston engine by means of which the valve disk and the valve seat of the valve assembly are made in con formity with each other during the engine is running. [008] An object of the invention is to provide a gas exchange valve by means of which the valve disk and the valve seat of the valve assembly are made in conformity with each other during the engine is running.

Disclosure of the Invention

[009] Objects of the invention can be met substantially as is disclosed in the independent claims and in the other claims describing more details of different embodiments of the invention.

[0010] A method of configuring a gas exchange valve assembly in an internal combustion piston engine comprises:

- providing a gas exchange valve

- providing a valve seat

- arranging an abrasive wearing overlay on a base material at a region of a seal ing surface of first one of the gas exchange valve disk and the valve seat,

- assembling the valve seat into a gas exchange valve body

- assembling the valve into the gas exchange valve body and while running the engine, rotating the valve around its longitudinal axis dur ing its lift and/or close movements such that the sealing surface of the valve de tach and/or touch the valve seat in the gas exchange valve body by a movement comprising a rotational component, wherein the abrasive wearing overlay ma chines the sealing surface of second one of the valve disk and the valve seat into conformity with each other.

[0011] This provides an in-situ machining that improves the conformance of valve and valve seat sealing surfaces for engine operation conditions.

[0012] According to an embodiment of the invention rotational position of the valve is changed by rotating it in one direction such that the abrasive overlay makes dimensional changes to sealing surface of the second one of the valve disk and the valve seat until the abrasive overlay is worn off from the sealing surface.

[0013] According to an embodiment of the invention the method comprises ar ranging an abrasive wearing overlay on the base material at a region of a sealing surface of the gas exchange valve disk and while running the engine, the valve is rotated around its longitudinal axis during its lift and/or close movements such that the sealing surface of the valve detach and/or touch the valve seat in the gas exchange valve body by a movement comprising a rotational component, wherein the abrasive wearing overlay machines the sealing surface of second one of the valve seat into conformity with the sealing surface of the valve until the abrasive surface has lost its abrasive effect. The abrasive effect is lost when the abrasive overlay has worn off or the abrasive particles have been dislodged from the overlay. [0014] The abrasive wearing overlay containing abrasive material on the valve sealing surface machines the respective the seat surface to achieve conform ance of the surfaces during running of the engine. This is achieved by making dimensional changes in the seat surface i.e. in addition to removing any local micro-protrusion on the valve seat surface use of the valve according to the in- vention makes the valve seat sealing surface to conform with the form of the valve disk through positive dimensional changes which changes a median line of a real surface of the valve disk. The overlay comprises abrasive particles of nano scale to micro scale. The abrasive particles will dislodge from the sealing surface during the machining process and will be mainly removed along the exhaust gases and engine lubrication oil.

[0015] The abrasive effect can be controlled by controlling the thickness of the coating and/or size of the abrasive particle. Due to the abrasive machining the abrasives are detached from the sealing surface, however the coating may be designed to further assist or improve the contact surface friction and wear per- formance. This technique will improve conformance of the contact surfaces and in the progress reducing maximum contact pressure and wear off the valve and valve seat surface and minimizes adhesive contact in the sealing surface during early stage of the engine running process.

[0016] According to an embodiment of the invention the abrasive wearing overlay is configured to wear away from the surface within less than 200 running hours of the engine. [0017] According to an embodiment of the invention arranging an abrasive wearing overlay on a sealing surface comprises arranging a matrix substance and abrasive particles embedded to the matrix substance on the base material.

[0018] According to an embodiment of the invention arranging an abrasive wearing overlay on a sealing surface comprises arranging a metal matrix with carbide particles therein as abrasives on the base material.

[0019] A gas exchange valve of an internal combustion piston engine, com prising a valve stem and a valve disc at a first end of the stem, wherein the valve disc has a sealing surface where a base material of valve disc sealing surface is provided with an abrasive wearing overlay.

[0020] According to an embodiment of the invention the base material com prises a hardened layer at its outer surface and the hardened layer is provided with the abrasive wearing overlay on top of it.

[0021] According to an embodiment of the invention the abrasive wearing overlay consist of a matrix substance and abrasive particles embedded to the matrix substance.

[0022] According to an embodiment of the invention the abrasive wearing overlay consist of metal matrix with carbide particles therein as abrasives.

[0023] According to an embodiment of the invention carbide is tungsten car- bide.

[0024] According to an embodiment of the invention the carbide grain size is 0.5 -20 pm.

[0025] According to an embodiment of the invention the abrasive wearing overlay comprises a first abrasive overlay and a second abrasive overlay, wherein the first abrasive overlay has a first amount of abrasive particles and the second abrasive overlay has a second amount of abrasive particles.

[0026] According to an embodiment of the invention the abrasive wearing overlay comprises a first abrasive overlay and a second abrasive overlay, wherein the first abrasive overlay has abrasive particles of first grain size and the second abrasive overlay has abrasive particles of second grain size.

[0027] According to an embodiment of the invention the abrasive wearing overlay comprises a diamond-like carbon (DLC) coating having a thickness more than 45 pm.

[0028] The overlay may be multi layered e.g. having different sizes of the abra sive particles in each layer.

[0029] Generally the base material selected for use in the gas exchange valve, particularly the valve disk is considerably hard material minimizing the wear. De- pending on the base material and the abrasive overlay it might be desirable to provide an additional treatment to the base material for improving the attachment of the abrasive overlay.

[0030] The abrasive overlay can be obtained on the base material making use of following methods, being not exclusive list but currently considered as advan- tageous methods.

Physical vapor deposition (PVD)

[0031] Physical vapor deposition (PVD) describes a variety of vacuum deposi tion methods which can be used to produce thin films and coatings. PVD is char- acterized by a process in which the material goes from a condensed phase to a vapor phase and then back to a thin film condensed phase. The most common PVD processes are sputtering and evaporation. PVD is used in the manufacture of items which require thin films for mechanical, optical, chemical or electronic functions. Some examples of implementing PVD method are as follows. [0032] Cathodic Arc Deposition, in which a high-power electric arc discharged at the source material blasts away some into highly ionized vapor to be deposited onto the workpiece. [0033] Electron beam physical vapor deposition, in which the material to be de posited is heated to a high vapor pressure by electron bombardment in high vac uum and is transported by diffusion to be deposited by condensation on the cooler workpiece. [0034] Evaporative deposition in which the material to be deposited is heated to a high vapor pressure by electrical resistance heating in high vacuum.

[0035] Close-space sublimation, where the material and substrate are placed close to one another and radiatively heated.

[0036] Pulsed laser deposition, in which a high-power laser ablates material from the target into a vapor.

[0037] Sputter deposition, in which a glow plasma discharge bombards the ma terial sputtering some away as a vapor for subsequent deposition.

[0038] Pulsed electron deposition, whereas highly energetic pulsed electron beam ablates material from the target generating a plasma stream under nonequilibrium conditions.

[0039] According to an embodiment the abrasive wearing layer comprises nano meter and/or micro-meter sized diamonds embedded in PVD coating.

Diamond-like carbon coating using PVD coating [0040] Diamond-like carbon (DLC) is a class of amorphous carbon material that displays some of the typical properties of diamond. DLC is usually applied as coatings to other materials that could benefit from some of those properties. The various forms of DLC can be applied to almost any material that is compatible with a vacuum environment. [0041] Even if DLC coatings are generally applied as a wear or corrosion protection coating, it has been discovered that if the coating is applied to form an increased thickness it exhibits a reverse behavior and becomes abrasive to an extent applicable to the invention. Suitable thickness to obtain the effect required to implement the invention is 45 micrometers or more.

[0042] According to an embodiment the abrasive wearing layer comprises nano meter and/or micro-meter sized diamonds embedded in DLC coating. [0043] According to an embodiment the abrasive wearing layer comprises nano meter and/or micro-meter sized diamonds embedded in coating provided by a combination of Cold spray coating and DLC coating.

Cold spray of tungsten carbide composite coating [0044] A cold spray coating technology is a coating deposition method. Solid powders are accelerated in a supersonic gas jet to velocities up to ca. 1200 m/s. During impact with the substrate, particles undergo plastic deformation and adhere to the surface. The kinetic energy of the particles, supplied by the expansion of the gas, is converted to plastic deformation energy during bonding.. [0045] The abrasive overlay comprises a metallic matrix into which carbides are embedded forming the abrasive part of the overlay. Metallic matrix is arranged to have a hardness of 200 - 350 HV and the carbides hardness is around 1000- 2000HV. Metallic matrix suitable for use in connection with the valve seat overlay according to the invention is NiCrBSi-alloy or CU based alloy. Carbide may be e.g. Tungsten Carbide, WC. The carbide grain size is fee-between 0.5 - 20 micrometers. The carbides will initially be fully embedded in the coating and as the metal matrix starts wearing carbides will be protruding and act as abrasives. Also, a friction enhancing materials may be added to the matrix

[0046] According to an embodiment the abrasive wearing layer comprises nano- meter and/or micro-meter sized diamonds embedded in cold spray coating. Smart Coating

[0047] A graded coating or sometimes referred to as a smart coating is applica ble in connection with the present invention. It is technically a monolayer coating but its composition changes gradual over its thickness. Smart coating can be obtained by using e.g. thermal and cold spray techniques. The smart coating can be tailored to needs at a certain time in the life of the coating by adding different abrasive and matrix compositions to the coating during the process. There can be different sizes of abrasives, different mixture grades of the metal matrix or additional material to improve thermal properties e.g. copper or even solid lubricants to improve tribological properties of the abrasive wearing overlay.

[0048] It is possible to obtain several advantageous effects. Firstly it is possible to improve running in and conformance of engine valves and valve seat surfaces. Secondly it is possible to reduce maximum contact pressure and wear off the valve/valve seat surface due to better conformance of the sealing surfaces and also minimize adhesive contact during early stage of the running in process. The abrasive particles will disappear during the engine is used.

[0049] The abrasive wearing overlay can be multi layered e.g. having different sizes of the abrasive particles in each layer.

[0050] The base material of both components, namely valve disc and valve seat, are extremely stiff, such that they will not conform elastically to each other, there fore the abrasive method is needed to embed the surfaces with each other.

[0051] The exemplary embodiments of the invention presented in this patent ap plication are not to be interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" is used in this patent application as an open limitation that does not exclude the existence of also unrecited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. The novel features which are considered as charac teristic of the invention are set forth in particular in the appended claims. 3D printing

3D printing method or a so called hybrid approach where a 3D printed overlay is created on top of a metallic matrix can be utilized with success. The 3D printed metals generally show a rough, and therefore abrasive surface, however using 3D printing similar material approach to the spray coating could be used.

Brief Description of Drawings

[0052] In the following, the invention will be described with reference to the ac companying exemplary, schematic drawings, in which Figure 1 depicts schematically valve assembly in which the sealing sur-face of the valve is provided with an abrasive overlay,

Figure 2 depicts schematically a valve assembly in which the sealing surface of the valve seat is provided with an abrasive overlay,

Figure 3 depicts schematically a structure of the sealing surface provided with an abrasive overlay according to an embodiment of the invention, and

Figure 4 depicts schematically a structure of the sealing surface provided with an abrasive overlay according to another embodiment of the invention.

Detailed Description of Drawings [0053] Figure 1 depicts schematically gas exchange valve assembly 10 of an internal combustion piston engine arranged to a cylinder head 12 of the engine. The gas exchange valve assembly is configured to controllably admit entry of combustion air into a combustion chamber 14 of the engine and removal of ex haust gases from the combustion chamber 14. The gas exchange valve assem- bly comprises a gas exchange valve 16, which may called simply as a valve, and a valve seat 18. The valve seat 18 is a ring-like member which has a sealing surface against which an intake or an exhaust valve rests during the stage of the engine operating cycle when that valve is closed. The sealing surface prevents gas leaking from the combustion chamber to the intake air receiver and to the exhaust gas manifold and it also functions as heat transfer surface for releasing heat from the valve 16 to the cylinder head 12. The valve 16 comprises a valve stem 16.1 and a valve disk 16.2 and a first end of the stem 16.1. The valve is supported by a valve guide 22 in the cylinder head.

[0054] The valve assembly is also provided with a valve rotator 20 which is con figured to rotate the valve around its longitudinal axis A by positive action, while the valve is moved in the direction of the longitudinal axis A. The valve seat 18 is coaxial with the valve 16. The valve rotator may be of a type know as such for a skilled person in the art, for example a so called ball spring rotator, or such as is disclosed e.g. in the publication EP0768450 B1 or DE102013013229 A1 the de scriptions of which are hereby incorporated by reference.

[0055] A so-called “rotocap” valve rotator incorporates a ball-retaining plate with ramped circumferential grooves for balls to roll along. A small spring pushes each of these balls to one side. A Belleville-type dished spring washer fits over these balls to form an upper race, which is supported on its outer edge by a spring-seat retainer. This retainer holds the whole assembly together and also provides a seat for the helical-coil valve springs. In the closed position of the valve, the dished spring washer is suspended between the spring-seat retainer and the ball- retainer, so that the balls move freely to a first end of the ramp and abut against the end of the groove. During opening stage of the valve, the dished spring washer deflects with the increase in the compression load on the valve spring. The outer edge of the dished washer bears against the spring-seat retainer as before, but the inner part of the washer now bears against the balls and hence pushes them along their ramps. The ramps are so shaped that, as contact with the washer is maintained, the spring-seat retainer is rotated and hence the valve is rotated by the same amount. As the valve closes, the washer comes back to its original position between the spring-seat retainer and the ball-retainer. This releases the load on the balls due to which the small bias springs now push the balls up their ramps and thereby bring the spring-seat retainer and the valve as sembly back to its starting position.

[0056] The valve disc is provided with a sealing surface 24 at its radial periphery region, which surface is typically at an angle with respect to the longitudinal axis A of the valve. Respectively, the valve seat 18 is provided with a sealing surface 26 which is ideally parallel to and in conformity with the sealing surface 24 of the valve. The valve disk 16.2 is made of a hard base alloy material, which is durable against wear. An abrasive wearing overlay 28 is arranged over the base material at the region of at least the sealing surface 24 of the valve 16. The sealing surface of the valve 16 may comprise a hardened layer which is provided with the abra sive wearing overlay 28. The valve 16 is made of material which experiences minimal deformations during its lifespan and is machined accurately to intended dimensions. [0057] In the figure 1 the valve 16 is at a position where it has just started its lift i.e. opening movement the sealing surface 24 of the valve has detached from the sealing surface 26 of the valve seat 18. The area of the sealing surfaces is shown in more detailed in the enlarged view encircled in the figure. In the view A there is indicated a cut-out line ll-ll which refer to the figure 2, in which the valve seat 18 is shown along the cut-out ll-ll. The view A depicts exemplary an angular flaw or non-conformance 30 in the seat surface 26. As is depicted in figure 2 the non-conformance may be a local, non-symmetrical deviation from a circular shape at a plane in the direction of the longitudinal axis A. Of course, the present invention is applicable regardless of the shape of the non-conformance. The gas exchange valve assembly in an internal combustion piston engine is configured for use such that firstly a gas exchange valve 16 and a valve seat 18 are provided and an abrasive wearing overlay is arranged on a base material at a region of a sealing surface of first one of the gas exchange valve disk and the valve seat. In particularly referring to the figure 1 the abrasive wearing overlay is arranged on the sealing surface of the gas exchange valve disk 16.2. The abrasive wearing overlay is arranged to cover the area of the valve 16 which is intended to form its sealing surface. In this case the dimensional accuracy of the valve disk is im portant because the valve seat is accommodated according to the shape of the valve disk. Next, the valve seat 18 and the valve 16 are assembled into a gas exchange valve body. While running the engine, the valve 16 is rotated around its longitu dinal axis during its lifting and/or closing movements such that the sealing surface 24 of the valve detach and/or touch the sealing surface 26 valve seat 18 in the gas exchange valve body by a movement comprising a rotational component. Thus when the abrasive wearing overlay simultaneously moves axially and an gularly in respect to the longitudinal axis, it also machines the sealing surface of second one of the valve disk and the valve seat into conformity with each other by forming a rotational fit between the surfaces. In particularly referring to the figure 1 the abrasive wearing overlay arranged on the sealing surface of the gas exchange valve disk 16.2 machines the sealing surface 26 of the valve seat 18 into conformity with the sealing surface 24 of the valve disk 16.2. The rotational position of the valve 16 is changed by rotating it in one direction. The abrasive overlay makes dimensional changes to sealing surface until the abrasive overlay or the abrasive material in the overlay is worn off from the sealing surface.

[0058] Figure 3 depicts schematically a valve assembly in which the sealing sur face of the valve seat is provided with an abrasive overlay 28. This embodiment is applicable when the valve seat is made of material which experiences minimal deformations during its lifespan and is machined accurately to intended dimen sions.

[0059] Figure 4 depicts schematically a structure of the base material 40, 41 pro vided with an abrasive overlay 28 according to an embodiment of the invention. The base material comprises a substrate i.e. the material of the base material of the valve disk 16.1 (or alternative the valve seat 18) which may have its outer surface area 41 hardened. The outer surface are 41 is a so called working sur face which comes to use when the abrasive overlay has been worn out. The outer surface 41 can be hardened making use of methods know as such, like a heat treatments, shot peening. A thick (advantageously 1-3mm) hard intermedi ate coating can be applied between the base material and the abrasive coating. The intermediate coating can be manufactured via Plasma Transferred Arc method or laser cladding. The intermediate coating material can be stellite or similar. [0060] Figure 5 depicts schematically a structure of the base material 40, 41 pro vided with an abrasive overlay 28’, 28” according to another embodiment of the invention. The abrasive wearing overlay 28’, 28” has different abrasive properties at its top region 28” and bottom region 28’. Like in the embodiment of the figure 4 the base material comprises a substrate i.e. the material of the base material of the valve disk 16.1 (or alternative the valve seat 18) which may have its outer surface area 41 hardened. The outer surface are 41 is a so called working sur face which comes to use when the abrasive wearing overlay has been worn out. The abrasive wearing overlay 28’, 28” may optionally comprise distinct layers having different abrasive properties. The abrasive wearing overlay 28’, 28” may also comprise regions from bottom to top having gradually changing abrasive properties. The different abrasive properties may be accomplished be providing different particle, or grain size of the abrasive particles and/or different amount of particles in the overlay.

[0061] The abrasive wearing overlay comprises a first abrasive overlay 28’ and a second abrasive overlay 28” on top of the first abrasive overlay, wherein the first abrasive overlay 28’ has abrasive particles of first grain size and the second abrasive overlay 28” has abrasive particles of second grain size, greater than the first grain size.

[0062] The abrasive wearing overlay comprises a first abrasive overlay 28’ and a second abrasive overlay 28”, wherein the first abrasive overlay 28’ has a fist amount, i.e. concentration of abrasive particles and the second abrasive over lay 28” has a second amount i.e. concentration of abrasive particles, being more than the first amount of abrasive particles.

[0063] As an example of the method according to the invention the abrasive wearing overlays may be formed as follows: The base material can be any suit able hard material selected in a view of minimizing wear and deformations in the use but also ensuring adequate corrosion resistance. Suitable materials are such as martensitic stainless steel, silicon-chromium steels, austenitic chromium- nickel steels or nickel-based super alloys. The base material may be hardened making use of suitable methods, such as heat treatment, shot peening, surface rolling etc. The following table shows some applicable selections for abrasive overlays in the method of the present invention.

[0064] While the invention has been described herein by way of examples in connection with what are, at present, considered to be the most preferred em- bodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various combinations or modifications of its features, and several other applications included within the scope of the in vention, as defined in the appended claims. The details mentioned in connection with any embodiment above may be used in connection with another embodi ment when such combination is technically feasible.

Claims

1. A method of configuring a gas exchange valve assembly in an internal combustion piston engine comprising: - providing a gas exchange valve

- providing a valve seat characterized by

- arranging an abrasive wearing overlay on a base material at a region of a seal ing surface of first one of the gas exchange valve disk and the valve seat, - assembling the valve seat into a gas exchange valve body

- assembling the valve into the gas exchange valve body

- and while running the engine, rotating the valve around its longitudinal axis dur ing its lift and/or close movements such that the sealing surface of the valve de tach and/or touch the valve seat in the gas exchange valve body by a movement comprising a rotational component, wherein the abrasive wearing overlay ma chines the sealing surface of second one of the valve disk and the valve seat into conformity with each other.

2. A method of configuring a gas exchange valve in an internal combustion piston engine according to claim 1, wherein the rotational position of the valve is changed by rotating it in one direction such that the abrasive overlay makes di mensional changes to sealing surface of the second one of the valve disk and the valve seat until the abrasive overlay is worn off from the sealing surface.

3. A method of configuring a gas exchange valve in an internal combustion piston engine according to claim 1, wherein the method comprises arranging an abrasive wearing overlay on the base material at a region of a sealing surface of the gas exchange valve disk and while running the engine, the valve is rotated around its longitudinal axis during its lift and/or close movements such that the sealing surface of the valve detach and/or touch the valve seat in the gas ex change valve body by a movement comprising a rotational component, wherein the abrasive wearing overlay machines the sealing surface of second one of the valve seat into conformity with the sealing surface of the valve, until the abrasive surface has lost its abrasive effect.

4. A method of configuring a gas exchange valve in an internal combustion piston engine according to claim 1, wherein the abrasive wearing overlay is con figured to wear away from the surface within less than 200 running hours of the engine.

5. A method of configuring a gas exchange valve in an internal combustion piston engine according to claim 1 , wherein arranging an abrasive wearing over lay on a sealing surface comprises arranging a matrix substance and abrasive particles embedded to the matrix substance on the base material.

6. A method of configuring a gas exchange valve in an internal combustion piston engine according to claim 1 , wherein arranging an abrasive wearing over lay on a sealing surface comprises arranging a metal matrix with carbide particles therein as abrasives on the base material.

7. A gas exchange valve of an internal combustion piston engine, compris ing a valve stem and a valve disc at a first end of the stem, wherein the valve disc has a sealing surface, characterized in that a base material of valve disc sealing surface is provided with an abrasive wearing overlay.

8. A gas exchange valve according to claim 7, characterized in that abra sive wearing overlay is configured to wear away from the surface within less than 200 running hours of the engine.

9. A gas exchange valve according to claim 7, characterized in that the base material comprises a hardened layer at its outer surface and the hardened layer is provided with the abrasive wearing overlay on top of it.

10. A gas exchange valve according to claim 7 or 9, characterized in that the abrasive wearing overlay consist of a matrix substance and abrasive particles embedded to the matrix substance.

11. A gas exchange valve according to claim 10, characterized in that the abrasive wearing overlay consist of metal matrix with carbide particles therein as abrasives.

12. A gas exchange valve according to claim 11, characterized in that car- bide is tungsten carbide.

13. A gas exchange valve according to claim 11, characterized in that the carbide grain size is 0.5 -20 pm.

14. A gas exchange valve according to claim 7, characterized in that the abrasive wearing overlay comprises a first abrasive overlay and a second abra- sive overlay, wherein the first abrasive overlay has a first amount of abrasive particles and the second abrasive overlay has a second amount of abrasive par ticles.

15. A gas exchange valve according to claim 7, characterized in that the abrasive wearing overlay comprises a first abrasive overlay and a second abra- sive overlay, wherein the first abrasive overlay has abrasive particles of first grain size and the second abrasive overlay has abrasive particles of second grain size.

16. A gas exchange valve according to claim 7, characterized in that the abrasive wearing overlay comprises a diamond-like carbon (DLC) coating having a thickness more than 45 pm.