DE102018127256B4 - Valve with a cover for an internal combustion engine - Google Patents

Abstract

Valve (10), preferably poppet valve, for an internal combustion engine with a combustion chamber (22), comprising:a closure part (16) with a bottom surface (18); and a cover (30) which at least partially covers the bottom surface (18), a heat-insulating air gap (32) being formed between the cover (30) and the bottom surface (18), which is in fluid communication when the valve (10) is closed with the combustion chamber (22) and/or an upper side of the cover (30) facing away from the heat-insulating air gap (32); characterized in that a) the heat-insulating air gap (32) has a circular cross section and/or is located essentially over its entire surface between the cover (30) and the bottom surface (18); andb) the heat-insulating air gap (32) has a substantially constant height of less than or equal to 2 mm, preferably approximately 1 mm.

Description

The invention relates to a valve, preferably a poppet valve, for an internal combustion engine. The valve has a cover.

It is known to provide a valve base (also called a valve head or valve bottom) with a cover or a heat shield in order to reduce the heat input into the valve body during combustion in a combustion chamber of the internal combustion engine.

For example, reveals the DE 32 47 487 A1 a poppet valve for internal combustion engines, in which a heat protection shield is arranged on the valve base. In order to improve the insulation and to simplify production, this heat protection shield is U-shaped when viewed in longitudinal section and is welded to the poppet valve to create an insulating space and at the same time apply valve seat armor.

From the US 1,868,138A A valve is known in which a valve head is modified into an enlarged central recess which cooperates with a comparatively flat cap member to provide a thermal insulation space for protecting the valve. The cap can be supported by a central boss and an insulating disk. The cap member may have a bead on its outer edge to come into contact with the engine block, preferably leaving a space between the cap and the top at the outer edge of the valve head.

The US 3,426,741 A discloses a poppet valve for diesel engines comprising a stem portion, a head portion connected to the stem portion, at least one fully enclosed and annularly arranged chamber within the metal mass comprising the head portion, and at least one annular ceramic ring positioned in the head to The chamber must be completely closed and sealed against the entry of hot combustion gases.

WO 2009/ 122 221 A1 discloses a poppet valve with a coolant channel in the valve stem and a receiving chamber in the valve head. A flow control valve is arranged in the receiving chamber, which controls the supply of coolant from the valve stem into the valve head.

US 1,873,119 A discloses a valve with a heat-insulating cover. The valve stem in turn has a coolant channel through which coolant is supplied to coolant channels in the valve head via a valve in the valve head.

DE 10 2006 061 128 A1 discloses a gas exchange valve of an internal combustion engine with a hollow valve plate with a valve base facing the fuel gas application and a hollow valve stem which completely penetrates the cavity of the valve plate.

US 2,787,992 A discloses an inlet valve with a disk made of steel or other non-corrosive material attached to the valve head and which can withstand the thermal stresses during operation.

The invention is based on the object of creating an alternative and/or improved valve for an internal combustion engine.

The task is solved by the features according to independent claim 1. Advantageous developments are specified in the dependent claims and the description.

The invention creates a valve (e.g. cylinder inlet valve or cylinder outlet valve), preferably a poppet valve, for an internal combustion engine (e.g. reciprocating piston internal combustion engine) with a combustion chamber. The valve has a closure part with a bottom surface. The valve has a cover that at least partially covers the floor area. A heat-insulating gap, namely an air gap, is formed between the cover and the base surface, which, when the valve is closed, is in a (e.g. direct and / or indirect) fluid connection with the combustion chamber and / or an upper side facing away from the heat-insulating gap Cover is.

The cover can allow a flame front to at least partially not touch the floor surface during combustion in the combustion chamber. The heat insulating gap can form a barrier that reduces heat conduction from the combustion chamber to the floor surface. This means that the surface temperature of the floor area cannot heat up as much as with conventional valves without a cover. Due to the reduced surface temperature of the floor surface, a reduced heat transfer coefficient from the combustion chamber to the valve can also result. The fluid connection to the heat-insulating gap can also enable fluid exchange to take place between the heat-insulating gap and the combustion chamber. This allows a pressure gradient between the combustion chamber and the heat-insulating gap to be reduced. This allows the cover to be made thin without being deformed during combustion. This can have the advantage that the thinner the cover, the less heat it can retain pick up the cover during combustion. The less heat the cover absorbs during combustion, the less heat the cover releases into the charge air during the charge cycle. The efficiency of the internal combustion engine is reduced to a lesser extent. A thin cover can also have the advantage that no or only relatively small valve pockets have to be provided in a piston of the internal combustion engine that can be moved back and forth.

In one embodiment, the fluid connection is designed to enable pressure approximation and/or pressure equalization between the combustion chamber and the heat-insulating gap.

In a further embodiment, a pressure on a top side of the cover and a pressure on a back side of the cover, which preferably faces the heat-insulating gap, are approximated and/or substantially equalized by the fluid connection during operation of the internal combustion engine.

In a further embodiment, the cover is arranged to separate a flame front from the floor surface during combustion in the combustion chamber.

In one embodiment, the fluid connection is formed by means of at least one through opening, preferably through hole or through slot, in the cover and/or in a connection (e.g. welded connection) between the cover and the bottom surface and/or the closure part.

Several through openings, e.g. B. through holes, through slots and / or annular gaps, preferably symmetrically, distributed in or on the cover.

For example, the at least one through hole can have a diameter between 0.5 mm and 5 mm or more.

In a further development, at least one through opening connects the top of the cover with a rear side of the cover and/or at least one through opening has a longitudinal axis which runs essentially perpendicular, oblique and/or parallel to the bottom surface. Alternatively or additionally, at least one through opening can run in an axial direction and/or a radial direction with respect to the valve.

In a further embodiment, the fluid connection is formed by means of an annular gap, preferably between the base surface and the cover.

Preferably, the annular gap can have a width between greater than or equal to 0.5 mm and/or less than or equal to 2 mm, preferably approximately 1 mm.

According to the invention, the heat-insulating gap extends essentially over the entire area between the cover and the bottom surface and/or the heat-insulating gap has a circular cross section (e.g. in a plane perpendicular to the longitudinal axis of the valve).

In one embodiment variant, the heat-insulating gap can also have a heat-insulating effect between the cover and the floor surface.

In a further embodiment variant, the cover essentially completely covers the floor surface and/or an outer peripheral edge of the cover is essentially flush with an outer peripheral edge of the floor surface.

According to the invention, the heat-insulating gap has a height less than or equal to 2 mm, preferably approximately 1 mm, and a substantially constant height.

In one embodiment, the cover is designed as a sheet, preferably sheet metal. The sheet preferably has a substantially constant sheet thickness. Alternatively or additionally, the sheet metal can have a sheet thickness greater than or equal to 0.5 mm and/or less than or equal to 2 mm, preferably approximately 1 mm.

In a further exemplary embodiment, the cover and/or the bottom surface is curved, preferably convex.

In a further exemplary embodiment, the cover follows a contour of the floor surface, preferably at a substantially constant distance.

In one embodiment, the cover is designed separately from the base surface and/or the closure part.

In a further embodiment, the cover is detachably attached to the base surface and/or the closure part, preferably mounted (e.g. by means of one or more screws, preferably countersunk screws).

In one embodiment variant, the cover is formed integrally in one piece with the base surface and/or the closure part.

In a further embodiment variant, the cover is welded to the base surface and/or the closure part, preferably by means of spot welding and/or friction welding.

In one embodiment, the closure part is designed as a valve plate and/or the bottom surface is designed as a valve plate bottom surface and/or the cover is essentially disk-shaped.

The closure part can expediently be movable for opening and closing the valve.

For example, the closure part can have a preferably annular sealing surface which is designed to rest on a preferably annular valve seat (e.g. on a bottom surface of a cylinder head of the internal combustion engine).

It is possible that the closure part serves or is designed to limit the combustion chamber of the internal combustion engine on the valve side.

Preferably, the valve may further include a valve stem connected to the closure member (e.g., integrally or releasably) to form a common, movable valve body of the valve.

The invention also relates to a motor vehicle, preferably a commercial vehicle (e.g. bus or truck), having a valve as disclosed herein.

It is also possible to use the valve as disclosed herein for passenger cars, large engines, off-road vehicles, stationary engines, marine engines, etc.

• 1 einen Querschnitt durch ein Abschnitt eines Ventilkörpers eines Ventils gemäß einem Ausführungsbeispiel der vorliegenden Offenbarung.

The previously described preferred embodiments and features of the invention can be combined with one another in any way. Further details and advantages of the invention are described below with reference to the accompanying drawing. It shows:

• 1 a cross section through a portion of a valve body of a valve according to an embodiment of the present disclosure.

The 1 shows a lower part of a valve 10. The valve 10 can expediently be formed as a poppet valve, as shown. However, other types of valves are also conceivable. The valve 10 can be, for example, an inlet or outlet valve of an internal combustion engine. The internal combustion engine can be, for example, a diesel, gasoline and/or gas fuel internal combustion engine. The internal combustion engine can be in a vehicle, e.g. B. motor vehicle, rail vehicle or watercraft, or a stationary system, e.g. B. for driving a generator or another unit. Preferably, the internal combustion engine can be included in a commercial vehicle, for example a truck or a bus.

The valve 10 has a valve body 12. The valve body 12 has a valve stem 14 (only partially shown) and a closure part 16 (also called valve head or valve base). The closure part 16 is designed, for example, as a valve plate, as shown. However, other shapes for the closure part 16 are also conceivable. The valve stem 14 is rod-shaped and guided longitudinally in a valve guide (not shown). The valve stem 14 merges into the closure part 16 at one end, preferably by means of a circumferential groove. The closure part 16 can be mushroom-shaped, for example. The closure part 16 has a bottom surface 18 on the combustion chamber side, preferably a valve plate bottom surface. The bottom surface 18 can delimit a combustion chamber 22 of the internal combustion engine on the valve side.

The valve stem 14 can be operated to open and close the valve 10, i.e. moved along its longitudinal axis. The actuation of the valve stem 14 of the valve 10 can be carried out using any known technique, e.g. B. mechanically by means of a valve train and/or a camshaft or electromagnetically, etc.

When the valve 10 is closed, the closure part 16 seals a fluid channel 20, e.g. B. an inlet channel or an outlet channel, opposite the combustion chamber 22 (see 1 ). An annular sealing surface of the closure part 16 is in contact with an annular valve seat 24 on a bottom surface 26 of a cylinder head 28. To open the valve 10, the closure part 16 lifts off from the valve seat 24. When the valve 10 is open, the closure part 16 is spaced from the valve seat 24 by an annular gap. Fluid can flow through the annular gap either from the fluid channel 20 into the combustion chamber 22 or vice versa. To close the valve 10, the closure part 16 returns into contact with the valve seat 24.

The valve 10 has a preferably disk-shaped cover 30. The cover 30 essentially completely covers the bottom surface 18 on the combustion chamber side. It is also possible that the cover 30 only partially covers the floor area.

The cover 30 can be designed separately or integrally with the closure part 16. In the illustrated embodiment the Cover 30 connected to the closure part 16 by means of a spot welding process. Other welding processes are also possible, e.g. B. Friction welding. However, it is also possible, for example, for the cover 30 to be detachably attached to the closure part 16, e.g. B. by means of one or more screws, preferably countersunk screws, etc.

The cover 30 is preferably designed as a thin sheet of metal. For example, the cover 30 can have a sheet thickness in a range between 0.5 mm and 2 mm, preferably approximately 1 mm. The sheet thickness of the sheet can be essentially constant.

The cover 30 is arranged at a distance from the floor surface 18. As shown, a cross-sectional contour of the cover 30 may follow a contour of the bottom surface 18, preferably at a substantially constant distance. For example, the cover 30 and the bottom surface 18 can be convexly curved. However, it is also possible for the cover 30 and/or the base surface 18 to have any other shape, up to and including a flat base surface 18 and a flat cover 30.

A gap 32, preferably an air gap, is formed between the cover 30 and the bottom surface 18. The gap 32 acts as a thermal insulation between the cover 30 and the bottom surface 18. During operation of the internal combustion engine, the cover 30 heats up very strongly. The cover 30 keeps the flame front away from the bottom surface 18 during combustion. The bottom surface 18 and the closure part 16 are not heated by the flame during combustion. In addition, the gap 32 hinders heat conduction from the highly heated cover 30 to the bottom surface 18. In this way, heat flow from the cover 30 to the closure part 16 can expediently be minimized.

The gap 32 can expediently extend essentially over the entire surface between the cover 30 and the bottom surface 18. The gap 32 can, for example, have a circular cross section in a plane perpendicular to the longitudinal axis of the valve 10.

The gap 32 can, for example, have a height between 0.5 mm and 2 mm, preferably approximately 1 mm. The gap 32 may have a substantially constant height.

During combustion, the cover 30 absorbs heat, which it releases to the inlet air, for example during the gas exchange. The thinner the cover 30 is, the less the charge air is warmed up and the less the efficiency of the internal combustion engine is reduced. Embodiments with a thin-walled sheet metal as a cover 30 can be advantageous in this context.

During the ignition of a fuel-air mixture in the combustion chamber 22, high ignition pressures can occur, for example in a range between 200 bar and 250 bar. To prevent a thin cover 30 from bending, for example during ignition of the fuel-air mixture, the gap 32 is in fluid communication with the combustion chamber 22. Fluid can thus be exchanged between the combustion chamber 22 and the gap 32. A pressure increase in the combustion chamber 22, for example during ignition and combustion of fuel, can also act on a back side of the cover 30 via the fluid connection. This enables pressure equalization between the combustion chamber 22 and the gap 32. A print on a front or top side of the cover 30 may substantially correspond to a print on a back or bottom side of the cover 30. At least the fluid connection can approximate a pressure on the back of the cover 30 to a pressure on the front of the cover 30. This prevents the cover 30 from bending due to an increase in pressure in the combustion chamber 22, without the cover 30 having a large material thickness for this purpose.

The fluid connection between the combustion chamber 22 and the gap 32 can be carried out in different ways, e.g. B. as through openings in the cover 30, as through openings in the connection between the cover 30 and the bottom surface 18 and / or as an annular gap between the cover 30 and the bottom surface 18. Preferably, the fluid connection is to be arranged in such a way that the fluid connection is (also) in the closed state of the valve 10 exists.

In the exemplary embodiment of 1 the fluid connection is formed by several axial through holes 34. The through holes 34 extend parallel to a longitudinal axis of the valve 10. The through holes 34 are arranged in the cover 30. The through holes 34 extend between a back of the cover 30 and a front or top of the cover 30.

In the exemplary embodiment of 1 the fluid connection is additionally formed by several radial through holes 36. The through holes 36 extend radially, preferably perpendicularly, to the longitudinal axis of the valve 10. The through passage holes 36 are formed between tacking points arranged on the outer circumference, which are formed by spot welding and connect the cover 30 to the bottom surface 18. In other words, the through holes 36 extend through or between a connection, preferably a welded connection, between the bottom surface 18 and the cover 30.

The fluid connection can, for example, also be formed additionally or alternatively in the form of an annular gap, which is arranged, for example, on the outer circumference between the cover 30 and the bottom surface 18. In such an exemplary embodiment, the cover 30 can be attached, for example, in the center to the bottom surface 18, e.g. B. by welding, preferably friction welding or spot welding, or releasably, for example, by means of a screw, preferably countersunk screw.

It is also possible for the cover 30 to have, for example, through slots or another internal or external structure for establishing fluid communication between the combustion chamber 22 and the gap 32. Of course, combinations of the disclosed fluid connections are also possible.

The invention is not limited to the preferred embodiments described above. Rather, a large number of variants and modifications are possible, which also make use of the inventive idea and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject matter and features of the subclaims, regardless of the claims referred to. In particular, the features of independent claim 1 are disclosed independently of one another. In addition, the features of the subclaims are also disclosed independently of all features of independent claim 1 and, for example, independently of the features relating to the presence and / or configuration of the floor surface and / or the cover of independent claim 1. All range information herein is to be understood to be disclosed in such a way that all values falling within the respective range are disclosed individually, e.g. B. also as the respective preferred narrower outer limits of the respective area.

Reference symbol list

10

Valve

12

Valve body

14

valve stem

16

Closure part

18

floor area

20

Fluid channel

22

Combustion chamber

24

Valve seat

26

floor area

28

cylinder head

30

cover

32

gap

34

through hole

36

through hole

Claims (14)

Valve (10), preferably poppet valve, for an internal combustion engine with a combustion chamber (22), comprising: a closure part (16) with a bottom surface (18); and a cover (30) which at least partially covers the base surface (18), a heat-insulating air gap (32) being formed between the cover (30) and the base surface (18), which is in a closed state of the valve (10). is in fluid connection with the combustion chamber (22) and/or an upper side of the cover (30) facing away from the heat-insulating air gap (32); characterized in that a) the heat-insulating air gap (32) has a circular cross section and/or extends essentially over the entire surface between the cover (30) and the base surface (18); and b) the heat-insulating air gap (32) has a substantially constant height of less than or equal to 2 mm, preferably approximately 1 mm. Valve (10). Claim 1 , wherein: the fluid connection is designed to enable pressure approximation and/or pressure equalization between the combustion chamber (22) and the heat-insulating air gap (32); and/or a pressure on the top of the cover (30) and a pressure on a back side of the cover (30) facing the heat-insulating air gap (32) are approximated and/or substantially balanced by the fluid connection during operation of the internal combustion engine becomes. Valve (10). Claim 1 or Claim 2 , wherein: the cover (30) is arranged to separate a flame front from the bottom surface (18) during combustion in the combustion chamber (22). Valve (10) according to one of the preceding claims, wherein: the fluid connection by means of at least one through opening (34, 36), preferably through hole or through slot, in the cover (30) and/or in a connection between the cover (30) and the bottom surface (18) and/or the closure part (16). Valve (10). Claim 4 , wherein: at least one through opening (34) connects a top of the cover (30) to a back of the cover (30); and/or at least one through opening (34, 36) has a longitudinal axis which runs essentially perpendicular, oblique and/or parallel to the bottom surface (18), and/or at least one through opening (34, 36) in an axial direction and/or runs in a radial direction with respect to the valve (10). Valve (10) according to one of the preceding claims, wherein: the fluid connection is formed by means of an annular gap, preferably between the bottom surface (18) and the cover (30). Valve (10) according to one of the preceding claims, wherein: the heat-insulating air gap (32) has a heat-insulating effect between the cover (30) and the base surface (18). Valve (10) according to one of the preceding claims, wherein: the cover (30) substantially completely covers the floor surface (18); and or an outer peripheral edge of the cover (30) is essentially flush with an outer peripheral edge of the bottom surface (18). Valve (10) according to one of the preceding claims, wherein: the cover (30) is designed as a sheet, preferably sheet metal, preferably: the sheet has a substantially constant sheet thickness; and or the sheet metal has a sheet thickness greater than or equal to 0.5 mm and/or less than or equal to 2 mm, preferably approximately 1 mm. Valve (10) according to one of the preceding claims, wherein: the cover (30) and the bottom surface (18) are curved, preferably convex; and or the cover (30) follows a contour of the bottom surface (18), preferably at a substantially constant distance. Valve (10) according to one of the preceding claims, wherein: the cover (30) is formed separately from the bottom surface (18) and/or the closure part (16); and or the cover (30) is detachably attached, preferably mounted, to the base surface (18) and/or the closure part (16). Valve (10) according to one of the preceding claims, wherein: the cover (30) is formed integrally with the bottom surface (18) and/or the closure part (16); and or the cover (30) is welded to the base surface (18) and/or the closure part (16), preferably by means of spot welding and/or friction welding. Valve (10) according to one of the preceding claims, wherein: the closure part (16) is designed as a valve plate; and or the bottom surface (18) is designed as a valve plate bottom surface; and or the cover (30) is essentially disk-shaped. Motor vehicle, preferably commercial vehicle, having a valve (10) according to one of the preceding claims.

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