INJECTION VALVE OF AN INTERNAL COMBUSTION ENGINE

Abstract

An injection valve for being in contact with an abrasive fluid has a cylinder having a cylinder length, an inner cylinder diameter and a cylinder wall, and a piston having an outer piston diameter and an outer piston face, the piston being movable in the cylinder. A first tubular liner is arranged between the cylinder wall and the piston so that the piston moves, at least partly, within the first tubular liner, the first tubular liner having a liner length, a first inner liner diameter and an inner liner face that has coating.

Claims

1.-10. (canceled)

11. An injection valve for being in contact with an abrasive fluid, the injection valve comprising: a cylinder having a cylinder length, an inner cylinder diameter and a cylinder wall, and a piston having an outer piston diameter and an outer piston face, the piston being movable in the cylinder, characterised in that a first tubular liner is arranged between the cylinder wall and the piston so that the piston moves, at least partly, within the first tubular liner the first tubular liner having a liner length, a first inner liner diameter and an inner liner face, the inner liner face comprising a coating.

12. An injection valve according to claim 11, wherein the liner length is longer than the inner cylinder diameter.

13. An injection valve according to claim 11, wherein the liner length is equal to or less than twice the first inner liner diameter.

14. An injection valve according to claim 11, wherein the injection valve further comprises a second tubular liner arranged in succession of the first tubular liner along the cylinder length.

15. An injection valve according to claim 14, wherein the second tubular liner has a second inner liner diameter larger than the first inner liner diameter.

16. An injection valve according to claim 11, wherein the injection valve further comprises a lubrication channel in the cylinder wall, extending towards the piston and configured to provide lubrication fluid or sealing oil to the piston.

17. An injection valve according to claim 11, wherein the coating comprises diamond-like-carbon, silicon dioxide (SiO.sub.2), graphite or graphene.

18. An injection valve according to claim 11, wherein the tubular liner has a first inner liner diameter being larger than a second inner liner diameter along the liner length.

19. An internal combustion engine comprising the injection valve according to claim 11.

20. A method of manufacturing the injection valve according to claim 11, comprising: providing the cylinder, the piston and the first tubular liner, coating the inner liner face of the first tubular liner, arranging the first tubular liner in the cylinder, fastening the first tubular liner in the cylinder by shrink-fitting, and arranging the piston at least partly within the cylinder.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which

[0058] FIG. 1 shows a cross-sectional view of an injection valve,

[0059] FIG. 2 shows a cross-sectional view of another injection valve,

[0060] FIG. 3 shows a cross-sectional view of part of the injection valve, and

[0061] FIG. 4 shows a cross-sectional view of part of an injection unit of an internal combustion engine.

[0062] All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

DETAILED DESCRIPTION OF THE INVENTION

[0063] FIG. 1 shows an injection valve 1 for being in contact with an abrasive fluid, such as fuel comprising coal particles, heavy fuel or methane, etc. The injection valve 1 comprises a cylinder 2 having a cylinder length L.sub.C, an inner cylinder diameter ID.sub.C and a cylinder wall 3. The cylinder 2 may be a hydraulic cylinder, a gas cylinder or a combustion cylinder. The injection valve 1 comprises a piston 4 having an outer piston diameter OD.sub.P and being movable in the cylinder 2. The injection valve 1 further comprises a first tubular liner 5, 5a arranged between the cylinder wall 3 and the piston 4, so that the piston 4 moves, at least partly, within the first tubular liner 5, 5a. The first tubular liner 5, 5a has a liner length L.sub.L longer than the inner cylinder diameter ID.sub.C and an inner liner diameter ID.sub.L. The first tubular liner 5, 5a has an inner face 6 comprising a coating 7.

[0064] When coating an inner surface, it is very difficult to coat the entire length of the cylinder 2 and obtain an even layer when the cylinder 2 is larger than the inner cylinder diameter ID.sub.C. Furthermore, the thickest layer will be closest to the end of the cylinder 2 while the thinner layer will be closer to the bottom of the cylinder 2, and such imprecisions in dimensions are not acceptable in an internal combustion engine. When having a tubular liner 5, 5a, 5b, the tubular liner 5, 5a, 5b can be coated from both ends, resulting in an even coating layer which is within the dimension variations acceptable within the field of internal combustion engines. After being coated, the tubular liner 5, 5a, 5b is inserted into the cylinder 2, resulting in a cylinder 2 having a surface resistant to wear when handling abrasive fluids.

[0065] In FIG. 1, the injection valve 1 comprises both a first tubular liner 5, 5a and a second tubular liner 5, 5b. Both tubular liners 5, 5a, 5b are coated before being inserted into the cylinder 2 and are arranged end-to-end in succession of each other along the cylinder length L.sub.C. The liner lengths L.sub.L of the first and second tubular liners 5, 5a, 5b are approximately the same in FIG. 1, but in another embodiment, the liner length L.sub.L of one tubular liner 5, 5a, 5b may be longer than the liner length L.sub.L of another tubular liner 5, 5a, 5b. The difference between the inner cylinder diameter ID.sub.C and the inner liner diameter ID.sub.L is twice the coating thickness t. The piston 4 is movable along the coating 7 of the tubular liners 5, 5a, 5b in the cylinder 2 to eject fluid out of an opening 9.

[0066] By the present coating processes, it is possible to coat a maximum length inside a cylinder being no longer than the inner cylinder diameter ID.sub.C when coating from one end. The liner length L.sub.L is therefore equal to or less than twice the inner liner diameter ID.sub.L because the tubular liner 5, 5a, 5b can be coated from both ends. The inner cylinder diameter ID.sub.C is less than 1 metre, preferably less than 0.5 metres, and more preferably less than 0.1 metre, and the inner liner diameter ID.sub.L is also less than 1 metre, preferably less than 0.5 metres, and more preferably less than 0.1 metre.

[0067] In FIG. 2, the injection valve 1 further comprises a lubrication channel 8 in the cylinder wall 3, extending towards the piston 4 and configured to provide lubrication fluid to the piston 4. Thus, the lubrication channel 8 has an outlet 11 facing an outer piston face 12. The second tubular liner 5, 5b has a second inner liner diameter ID.sub.Lb smaller than the first inner liner diameter ID.sub.La, ID.sub.L. The first inner liner diameter ID.sub.La, ID.sub.L substantially corresponds to the outer piston diameter OD.sub.P. The inner face 6 of the first tubular liner 5, 5a contacts the outer face 12 of the piston 4 and controls the sideways/radial movement of the piston 4 in and out of the cylinder 2. Due to the fact that the second tubular liner 5, 5b has a second inner liner diameter ID.sub.Lb smaller than the first inner liner diameter ID.sub.La, ID.sub.L, there is a gap between the inner face 6 of the second tubular liner 5b, 5 and the outer piston face 12. This gap transports the lubrication fluid from the lubrication channel 8 along the piston 4 towards the opening 9 and ensures that the abrasive fluid in the cylinder 2 does not enter between the outer piston face 12 of the piston 4 and the inner face 6 of the first tubular liner 5, 5a. The gap is smaller than 1 mm, preferably smaller 100 μm, even preferably smaller than 50 μm. By keeping a higher pressure in the lubrication fluid than in the abrasive fluid in the cylinder 2, the abrasive fluid does not enter between the first tubular liner 5, 5a and the piston 4, and the wear on the cylinder 2 and the piston 4 is substantially decreased since the abrasive fluid is no longer squeezed in between the piston 4 and the cylinder wall 3. As can be seen, the first tubular liner 5, 5a and the second tubular liner 5, 5b are arranged in succession but with a distance d therebetween them. Hereby, the first and the second tubular liner 5, 5a, 5b form an annular channel 16 in fluid communication with the lubrication channel 8, and the lubrication fluid can thus be distributed along the annular channel 16 extending all around the piston 4. A recess 14 or annular groove (not shown) in an outer face 19 of the first and second tubular liners 5, 5a, 5b has been formed for distributing the lubrication fluid better before being ejected through the outlet 11. Thus, the outlet 11 is in the annular channel 16. As shown in FIG. 2, the injection valve 1 may also comprise a third tubular liner 5, 5c, so that the cylinder is lined with three tubular liners 5, 5a, 5b, 5c.

[0068] In FIGS. 1 and 2, the total liner length being an addition of each liner length LL is equal to the cylinder length L.sub.C. The coating thickness t is uniform along the liner length L.sub.L, and the coating thickness t is less than 1 mm, preferably less than 100 μm. The tubular liners 5, 5a, 5b are preferably made of metal. The coating 7 comprises diamond-like-carbon, silicon dioxide (SiO.sub.2), graphite, such as graphene, or the like coating material. The coating 7 has a shore hardness higher than 1000 HV.

[0069] In order to even out a very small variation in the inner liner diameter ID.sub.L of two tubular liners 5, 5a, 5b, a first end 17 of the first tubular liner 5, 5a and a second end 18 of the second tubular liner 5, 5b may be chamfered, resulting in a tapering end 15, as shown in FIG. 3. The inner liner diameter ID.sub.L of a tubular liner 5 may vary along the liner length L.sub.L so that the inner liner diameter ID.sub.L of the tubular liner 5 has a first inner liner diameter ID.sub.La which is larger than a second inner liner diameter ID.sub.Lb along the liner length L.sub.L, resulting in an increasing thickness t.sub.L, as shown in FIG. 3.

[0070] FIG. 4 shows part of an injection unit of an internal combustion engine 100 comprising the injection valve 10, where the cylinder 2 and the piston 4 form part of an intensifier (not shown). The first tubular liner 5, 5a has an inner diameter ID.sub.Lb slightly larger than the inner diameter ID.sub.La of the second and third tubular liners 5, 5b, 5c, and the second tubular liner 5b has the annular channel 16 for providing lubrication fluid to the injection unit.

[0071] The injection valve 1, 10 is manufactured by first providing a cylinder 2, a piston 4 and a first tubular liner 5, 5a, then coating the inner liner face 6 of the first tubular liner 5, 5a forming the coating 7, and finally arranging the first tubular liner 5, 5a in the cylinder 2. The first tubular liner 5, 5a is fastened in the cylinder 2 by shrink-fitting, and subsequently, the piston 4 is at least partly arranged within the cylinder 2 and thus within the first tubular liner 5, 5a. If the cylinder 2 comprises a second tubular liner 5, 5b, the second tubular liner 5, 5b is arranged in succession of the first tubular liner 5, 5a before the step of fastening the first tubular liner 5, 5a, and before the piston 4 is arranged in the cylinder 2, both liners 5a, 5b, 5 are fastened to the cylinder 2. The inner liner faces 6 comprising coating 7 may be polished and/or grinded before the piston 4 is arranged in the cylinder 2.

[0072] The fluid is a gas, a liquid or a combination thereof. The fluid is any kind of fluid in an internal combustion engine, such as heavy fuel, fuel containing particles, such as coal particles, liquefied gas, such as Liquefied Petroleum Gas (LPG), dimethyl ether (DME), gasoline or other liquids with abrasive particles or just liquids with poor lubricity.

[0073] Although the invention has been described in the above in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.