WO2017044080A1

WO2017044080A1 - Method for lubricating engine equipment

Info

Publication number: WO2017044080A1
Application number: PCT/US2015/049093
Authority: WO
Inventors: Allison ATHEY
Original assignee: Volvo Truck Corporation
Priority date: 2015-09-09
Filing date: 2015-09-09
Publication date: 2017-03-16

Abstract

An engine arrangement for use with Dimethyl Ether (DME) fuel includes an engine adapted for use with DME fuel, a coolant system arranged to direct coolant to the engine to cool the engine, and equipment associated with the engine, the equipment including parts that at least one of reciprocate and rotate. The equipment including one or more passages forming part of the coolant system and arranged to direct coolant to one or more lubrication locations of the parts for lubrication of the parts.

Description

ENGINE ARRANGEMENT FOR USE WITH DIMETHYL ETHER FUEL AND HAVING LUBRICATED EQUIPMENT AND METHOD FOR LUBRICATING EQUIPMENT ASSOCIATED WITH SUCH AN ENGINE ARRANGEMENT

BACKGROUND AND SUMMARY

[0001] The present invention relates generally to engine arrangements for use with dimethyl ether fuel and methods involving such engine arrangements and, more particularly, to such engine arrangement with lubricated equipment and methods for lubricating such equipment.

[0002] Piston driven fuel pumps in dimethyl ether (DME) engine arrangements are presently lubricated with engine oil. The engine oil gets on the walls of the cylinder. The DME is a solvent and washes the oil off the walls. This leads to engine oil in the DME. The engine oil/DME interaction leads to a deposit/sludge issue in DME fuel systems. The sludge issue can cause maintenance intervals to be very short and, more particularly, shorter than traditional diesel engines. The sludge clogs the fuel filters and fuel system. This causes the entire fuel system to require flushing with special chemicals to maintain functionality.

[0003] The sludge forms when DME and engine oil interact, and it is presently understood that this is due to chemical polarity/solubility differences between the DME and oil. Particularly problematic components of engine oil for DME are polyisobutylene succinimides (PIBS) and viscosity modifiers (VM). PIBS disperse soot in oil and make up a portion of engine oil. VMs modify the engine oil viscosity to allow oil to operate at low and high temperatures and are also an important part of the oil additive package.

[0004] It is therefore desirable to provide an engine arrangement and method for lubricating equipment of an engine arrangement that reduces the possibility of introducing engine oil into DME fuel.

[0005] The inventor proposes lubricating engine arrangement equipment such as a piston driven fuel pump with coolant. In the past, fuel pumps have not been lubricated with coolant because getting water into traditional fuels would be extremely detrimental and coolant is not normally an ideal lubricant. The inventor has recognized, however, that getting small amounts of coolant into DME, on the other hand, should not cause a problem.

[0006] Coolant has its own natural lubrication, as it lubricates the water pump. Coolant is ordinarily mainly water and ethylene glycol with small amounts of other additives. Because fuel pumps are typically lubricated with oil or fuel (depending upon the type of pump), lubricating the fuel pump with coolant having less effective lubricating properties might call for upgrading materials of the fuel pump or providing additional lubricating additives to the coolant. Water and DME are known to be miscible. In fact, DME can solubilize more water than traditional fuels, but too much water in DME can still cause engine issues. DME and water are compatible as both are polar. DME should also successfully dissolve ethylene glycol, as it is known to be soluble in most organic solvents.

[0007] Using coolant to lubricate engine arrangement equipment offers advantages in that it offers a solution to the deposit/sludge issue that does not require significant engine redesign or chemical testing to determine which oil components need to be removed. Indeed, removing all the oil components that can cause deposit/sludge issues may make the oil itself unviable, as it may not provide enough engine lubrication protection.

[0008] In accordance with an aspect of the present invention, an engine arrangement for use with Dimethyl Ether (DME) fuel is provided, the engine arrangement comprising an engine adapted for use with DME fuel, a coolant system arranged to direct coolant to the engine to cool the engine, a fuel tank, and a fuel pump arranged to pump fuel from the fuel tank to the engine, the fuel pump having a body having a cylinder and a piston arranged to reciprocate in the cylinder, the body including one or more passages forming part of the coolant system and arranged to direct coolant to one or more piston lubrication locations for lubrication of the piston.

[0009] In accordance with another aspect of the present invention, an engine arrangement for use with Dimethyl Ether (DME) fuel is provided, the engine arrangement comprising an engine adapted for use with DME fuel, a coolant system arranged to direct coolant to the engine to cool the engine, and equipment associated with the engine, the equipment including parts that at least one of reciprocate and rotate, the equipment including one or more passages forming part of the coolant system and arranged to direct coolant to one or more lubrication locations of the parts for lubrication of the parts.

[0010] In accordance with yet another aspect of the present invention, a method of lubricating equipment associated with an engine arrangement for use with Dimethyl Ether (DME) fuel is provided, the method comprising reciprocating or rotating parts of equipment associated with the engine arrangement, and directing coolant from a coolant system of the engine arrangement to one or more lubrication locations of the equipment to lubricate the parts.

BRIEF DESCRIPTION OF THE DRAWINGS

[001 1] The features and advantages of the present invention are well understood by reading the following detailed description in conjunction with the drawings in which like numerals indicate similar elements and in which:

[0012] FIG. 1 schematically shows an engine arrangement according to an aspect of the present invention;

[0013] FIG. 2 schematically shows a fuel pump for use with an engine arrangement according to an aspect of the present invention; and

[0014] FIG. 3 schematically shows a fuel pump for use with an engine arrangement according to another aspect of the present invention.

DETAILED DESCRIPTION

[00 IS] FIG. 1 shows an engine arrangement 21 for use with Dimethyl Ether (DME) fuel according to an embodiment of the present invention. The DME fuel is typically additized DME comprising DME, a lubricity additive, an odorant, and any other additives deemed necessary. The engine arrangement 21 includes an engine 23 adapted for use with DME fuel, a coolant system 25 including a heat exchanger 25a and arranged to direct coolant to the engine to cool the engine, a fuel tank 27, and a high pressure fuel pump 29 arranged to pump fuel from the fuel tank to the engine. A low pressure pump 55 supplies fuel to the high pressure fuel pump 29 from the fuel tank 27. The high pressure pump 29 is used to supply fuel to the high pressure rail 47 located on the engine for fuel injection.

[0016] The fuel pump 29 has a body 31 having a cylinder 33 and a piston 35 arranged to reciprocate in the cylinder. The body 31 includes one or more passages 37 connected to the heat exchanger 25a and forming part of the coolant system 25 and arranged to direct coolant to and, typically, from one or more piston lubrication locations 39 for lubrication of the piston 35. The term "passages" is defined herein as referring to any manner of opening, conduit, hose, tube, channel, container, nozzle, or other avenue through which coolant might flow.

[0017] The coolant system 25 typically includes the heat exchanger 25a, typically a radiator, an expansion tank (not shown), and passages 41 leading to and from the heat exchanger, passages through or around equipment to be cooled, such as passages 43 through the engine block, and a pump (not shown) to pump coolant through the various passages. The coolant is preferably a mixture of water and ethylene glycol with small amounts of other additives that, if mixed in minimal amounts with DME, will not be harmful to operation of the engine. Water and DME are known to be miscible, and DME can solubilize more water on a percentage basis than traditional fuels. DME will also successfully dissolve ethylene glycol as it is known to be soluble in most organic solvents.

[0018] The fuel pump 29 comprises a rotatable drive shaft 45 and means for reciprocating the piston 35 driven by the drive shaft. The fuel pump 29 is ordinarily a high pressure pump that provides fuel under high pressure to, e.g., a common rail 47 with injectors (not shown) that inject fuel into cylinders (not shown) of the engine.

[0019] The drive shaft 45 for the fuel pump 29 is typically linked to a crankshaft (not shown) of the engine 23. A variety of means can be provided for reciprocating the piston. FIG. 2 shows a reciprocating means in the form of a cam 49a that is non-rotatably mounted on and driven by the drive shaft 45. The cam 49a contacts a cam follower 49b on the piston 35 to push the piston 35 to a top dead center position in the cylinder 33 to force fuel out of the cylinder through a one-way valve 51 to the rail 47. A spring 49c is arranged to push the cam follower 49b on the piston 35 against the cam 49a so that the piston withdraws to a bottom dead center position in the cylinder 33. When in the bottom dead center position, fuel at a lower pressure can be pumped into the cylinder 33 past a one-way valve 53 by a low pressure fuel pump 55 that is typically located in the fuel tank 27. In many arrangements, such as the arrangement shown in FIG. 2, the drive shaft 45 is linked to the crankshaft of the engine so that the drive shaft rotates at one half the speed of the crankshaft. Often, the cam 49a on such a drive shaft 45 will have two lobes for raising and lowering the piston twice during each revolution of the drive shaft.

[0020] In the fuel pump 29 of FIG. 2, the body 31 comprises one or more passages 57 connected to the heat exchanger 25a and forming part of the coolant system 25 and arranged to direct coolant to one or more lubrication locations 59 for lubrication of the reciprocating means.

[0021] The passages 37 arranged to direct coolant to the piston lubrication locations 39 may lead to an annular groove 61 in the wall of the cylinder 33, the groove extending around the piston to passages 37 arranged to direct coolant back to the heat exchanger 25a. The piston 35 may be provided with piston rings 63 that remain above the groove 61 when the piston is in a bottom dead center position to minimize the possibility of coolant mixing with fuel in the cylinder 33. Piston rings (not shown) may also be provided that remain below the groove 61 when the piston is in the top dead center position, however, it is also possible to permit coolant to flow into a crankcase 65 of the fuel pump 29 to facilitate lubrication of the reciprocating means. [0022] Where the reciprocating means comprises a cam 49a mounted on the drive shaft 45 as shown in FIG. 2, the one or more passages 57 can direct coolant to lubrication locations 59 for lubrication of the cam 49a and cam follower 49b. Lubricating coolant can be sprayed onto the cam 49a and cam follower 49b from the passages 57 or nozzles (not shown) associated with the passages, or can be contained in the crankcase 65 of the fuel pump 29 so that the cam 49a and cam follower 49b are lubricated as the cam turns through the coolant in the crankcase.

Ordinarily there will be no air in the coolant system and the crankcase 65 will be filled with coolant so that the moving parts and friction surfaces are submerged in the coolant/lubricant.

[0023] FIG. 3 shows an alternative form of fuel pump 29^* wherein the reciprocating means comprises a piston rod 49a' rotatably attached to the piston 35' and to a crank 49b' that is non- rotatably mounted on and driven by the drive shaft 45'. The body 3 Γ of the fuel pump 29' comprises one or more passages 57' forming part of the coolant system 25 and arranged to direct coolant to one or more lubrication locations 59' for lubrication of the piston rod 49a' and bearings or bushings connecting the piston rod to the brank 49b' and the piston 35'. The fuel pump 29' can be otherwise identical to the fuel pump 29 shown in FIG. 2.

[0024] The present invention is presently contemplated as being particularly useful in connection with lubrication of components of a high pressure fuel pump of an engine

arrangement for use with DME fuel.

[0025] In a method oflubricating equipment associated with an engine arrangement 21 for use with DME fuel, parts such as pistons 35 in cylinder 33, cams 49a and cam followers 49b, and bushings and bearings associated with piston rods, are reciprocated or rotated. Coolant is directed from a coolant system 25 of the engine arrangement 21 to one or more lubrication locations 39 and 59 of the equipment to lubricate the parts. For example, where the equipment comprises a cylinder 33 and a piston 35 that reciprocates in the cylinder, the coolant can be directed to a piston lubrication location 39 between the piston and the cylinder. Where the equipment comprises a cam 49a and a cam follower 49b, the coolant can be directed to a lubrication location between the cam and the cam follower. Where the equipment comprises a crankshaft crank 49b' and a piston 35' connected to the crankshaft crank by a piston rod 49a', the coolant can be directed to a lubrication location between the crankshaft crank and the piston rod, and a lubrication location between the piston rod and the piston, such as at bushings or bearings connecting those components.

[0026] In the present application, the use of terms such as "including" is open-ended and is intended to have the same meaning as terms such as "comprising" and not preclude the presence of other structure, material, or acts. Similarly, though the use of terms such as "can" or "may" is intended to be open-ended and to reflect that structure, material, or acts are not necessary, the failure to use such terms is not intended to reflect that structure, material, or acts are essential. To the extent that structure, material, or acts are presently considered to be essential, they are identified as such.

[0027] While this invention has been illustrated and described in accordance with a preferred embodiment, it is recognized that variations and changes may be made therein without departing from the invention as set forth in the claims.

Claims

WHAT IS CLAIMED IS:

1. An engine arrangement for use with Dimethyl Ether (DME) fuel, comprising:

an engine adapted for use with DME fuel;

a coolant system arranged to direct coolant to the engine to cool the engine;

a fuel tank; and

a fuel pump arranged to pump fuel from the fuel tank to the engine, the fuel pump having a body having a cylinder and a piston arranged to reciprocate in the cylinder, the body including one or more passages forming part of the coolant system and arranged to direct coolant to one or more piston lubrication locations for lubrication of the piston.

2. The engine arrangement as set forth in claim 1 , wherein the fuel pump comprises a rotatable drive shaft and means for reciprocating the piston driven by the drive shaft.

3. The engine arrangement as set forth in claim 2, wherein the body comprises one or more passages forming part of the coolant system and arranged to direct coolant to one or more lubrication locations for lubrication of the reciprocating means.

4. The engine arrangement as set forth in claim 2, wherein the reciprocating means comprises a cam mounted on the drive shaft.

5. The engine arrangement as set forth in claim 4, wherein the body comprises one or more passages forming part of the coolant system and arranged to direct coolant to one or more lubrication locations for lubrication of the cam.

6. The engine arrangement as set forth in claim 2, wherein the reciprocating means comprises a piston rod attached to the piston and the drive shaft.

7. The engine arrangement as set forth in claim 6, wherein the body comprises one or more passages forming part of the coolant system and arranged to direct coolant to one or more lubrication locations for lubrication of the piston rod.

8. The engine arrangement as set forth in claim 1 , comprising passages between the one or more lubrication locations and the coolant system for returning coolant to the cooling system.

9. An engine arrangement for use with Dimethyl Ether (DME) fuel, comprising:

an engine adapted for use with DME fuel;

a coolant system arranged to direct coolant to the engine to cool the engine; and equipment associated with the engine, the equipment including parts that at least one of reciprocate and rotate, the equipment including one or more passages forming part of the coolant system and arranged to direct coolant to one or more lubrication locations of the parts for lubrication of the parts.

10. The engine arrangement as set forth in claim 9, wherein the equipment comprises a cylinder and a piston reciprocably movable in the cylinder, and the one or more lubrication locations comprises a lubrication location between the piston and the cylinder.

1 1. The engine arrangement as set forth in claim 10, wherein the equipment comprises a cam and a cam follower, and the one or more lubrication locations comprises a lubrication location between the cam and the cam follower.

12. The engine arrangement as set forth in claim 10, wherein the equipment comprises a crankshaft and a piston connected to the crankshaft by a piston rod, and the one or more lubrication locations comprises a lubrication location between the crankshaft and the piston rod, and a lubrication location between the piston rod and the piston.

13. The engine arrangement as set forth in claim 9, wherein the equipment comprises a cam and a cam follower, and the one or more lubrication locations comprises a lubrication location between the cam and the cam follower.

14. The engine arrangement as set forth in claim 9, wherein the equipment comprises a crankshaft and a piston connected to the crankshaft by a piston rod, and the one or more lubrication locations comprises a lubrication location between the crankshaft and the piston rod, and a lubrication location between the piston rod and the piston.

15. The engine arrangement as set forth in claim 9, wherein the equipment comprises a fuel pump.

16. A method of lubricating equipment associated with an engine arrangement for use with Dimethyl Ether (DME) fuel, comprising: reciprocating or rotating parts of equipment associated with the engine arrangement; and directing coolant from a coolant system of the engine arrangement to one or more lubrication locations of the equipment to lubricate the parts.

17. The method as set forth in claim 16, wherein the equipment comprises a cylinder and a piston that reciprocates in the cylinder, the coolant being directed to a lubrication location between the piston and the cylinder.

18. The method as set forth in claim 16, wherein the equipment comprises a cam and a cam follower, the coolant being directed to a lubrication location between the cam and the cam shaft.

19. The method as set forth in claim 16, wherein the equipment comprises a crankshaft and a piston connected to the crankshaft by a piston rod, the coolant being directed to a lubrication location between the crankshaft and the piston rod, and a lubrication location between the piston rod and the piston.