WO2009005662A2

WO2009005662A2 - Engine pre-lubrication system

Info

Publication number: WO2009005662A2
Application number: PCT/US2008/007904
Authority: WO
Inventors: Aaron C. Luft; Allen R. Bowman; Joseph R. Brinker; Donald J. Lockbridge; Colin A. Hawkins
Original assignee: Caterpillar Inc.
Priority date: 2007-06-29
Filing date: 2008-06-25
Publication date: 2009-01-08
Also published as: WO2009005662A3; CN101688449A; US20090000592A1; DE112008001779T5; CN101688449B

Abstract

A system (10) for pre-lubricating an engine (12) is disclosed. The system (10) has the engine (12), a first pump (22) driven by the engine (12) to lubricate the engine (12), and a second pump (42) configured to lubricate the engine (12). The system (10) also has at least one component driven by the engine (12) and fluidly connected downstream of the second pump (42) and upstream of the engine (12). System (10) further has a sensor (54) located at the engine (12) to generate a signal indicative of an engine lubrication status. Starting of the engine (12) is inhibited based on the engine lubrication status.

Description

ENGINE PRE-LUBRICATION SYSTEM

Technical Field The present disclosure is directed to a lubrication system and, more particularly, to an engine pre-lubrication system.

Background

Machines, including construction, on-highway, and agriculture vehicles, have a main power source for moving the machine, powering a tool, or driving other operations. The main power source most often includes an internal combustion engine, such as a diesel engine, a gasoline engine, a gaseous fuel- powered engine, or any other type of engine. Components of these engines are subjected to high loads to effect combustion and transmit power to driven components. A lubrication system is necessary to protect engine components from wear and tear caused by operating under these high loads. It has been regularly observed that engine components are exhausted before expected, even though they were properly installed and the lubrication system was operating as designed.

Much wear and tear occurs at engine startup. That is, when a conventional engine is cold, the lubricant normally coating the engine components has typically seeped out of the galleys among these components. Thus, during ignition cranking, the engine components interact in an un- lubricated condition and suffer a relatively great amount of wear before adequate oil pressure and lubrication can be built up. One method that has been implemented by engine manufacturers to prevent an un-lubricated condition at startup is described by U.S. Patent No. 4,502,431 (the '431 patent), issued to Lulich on 5 March 1985. The '431 patent discloses that oil is pumped within engine passageways for a period of time sufficient to provide an operational oil pressure level in the engine prior to cranking. This result may be accomplished by providing a supplemental oil pump, which is conveniently driven from the starter motor armature shaft of the engine. When a starter switch of the engine is moved to a heat position to activate glow plugs in preparation for starting, an electrical impulse is also provided to initiate the rotation of the starter motor armature shaft to drive the supplemental oil pump, thereby bringing oil pressure up to operational levels while the operator waits on heating of the glow plugs to initiate cranking. The supplemental oil pump communicates with the engine lubrication system and distributes oil under pressure through a plurality of conduits to the engine's crankshaft bearings, turbocharger unit, valve train assembly, pistons, filtering assembly, and other engine components requiring lubrication. The '431 patent discloses that pre-combustion lubrication may be controlled by a time-delay ignition switch.

Although the method of the '431 patent may provide sufficient engine lubrication prior to engine starting in some situations, it may fail to provide adequate lubrication for all components driven by the engine. Specifically, the '431 provides no method for actively checking and ensuring that all engine-driven components are lubricated prior to starting. Thus, it may be possible that the engine could be started, forcing un-lubricated engine-driven components into contact, resulting in an excessive amount of wear and tear of those components. In addition, the time delay switch may not provide adequate lubrication under all conditions. Instead, the switch merely delays ignition for a set period of time and then starts the engine regardless of an actual lubrication status, again providing opportunities for un-lubricated parts to come into contact with each other. And the delay switch may fail to account for varying temperatures and other ambient conditions that impact lubrication rates. When these conditions are unaccounted for, the pre-lubrication time period may be too short to allow for adequate lubrication.

The present disclosure is directed to overcoming the problems set forth above.

Summary of the Invention

In one aspect, the present disclosure is directed to a system for pre-lubricating an engine. The system includes an engine, a first pump driven by the engine to lubricate the engine, and a second pump configured to lubricate the engine. The system also includes at least one component driven by the engine and fluidly connected downstream of the second pump and upstream of the engine. The system further includes a sensor located at the engine to generate a signal indicative of an engine lubrication status. Starting of the engine is inhibited based on the engine lubrication status.

In another aspect, the present disclosure is directed toward a method of providing lubrication to an engine system. The method includes drawing power from an engine to pressurize lubricant at a first location, and pressurizing the lubricant at a second location. The method also includes passing the lubricant through an engine-driven component located upstream of the engine, and passing the lubricant through the engine. The method further includes inhibiting engine ignition based on a pressure of the lubricant in the engine.

Brief Description of the Drawings

FIG. 1 is a schematic illustration of an exemplary disclosed power system.

Detailed Description

Fig. 1 illustrates an exemplary embodiment of a power system 10. Power system 10 includes an internal combustion engine 12 having a lubrication system 14 and a starting control system 16. One skilled in the art will recognize that engine 12 may be any type of internal combustion engine such as, for example, a diesel engine, a gasoline engine, or a gaseous fuel-powered engine. Engine 12 may include an engine block 11 that at least partially defines a plurality of cylinders (not shown), a piston (not shown) slidably disposed within each cylinder, and a cylinder head (not shown) associated with each cylinder. Engine 12 may also include a crankshaft (not shown) that is rotatably supported within engine block 11 by way of a plurality of journal bearings (not shown). A connecting rod (not shown) may connect each piston to the crankshaft so that a sliding motion of the piston within each respective cylinder results in a rotation of the crankshaft. The cylinders, pistons, and cylinder heads together may form a combustion chamber (not shown).

Surfaces of the cylinders, pistons, crankshaft, and bearings come into contact with each other when motion of engine 12 begins. Constant and adequate lubrication may be necessary to prevent damage to these engine surfaces during metal-on-metal contact resulting from the motion thereof. Accordingly, engine 12 may include lubrication passageways (not shown) for transporting a lubricating fluid to the bearing surfaces and galleys of engine 12. A fuel pump 18 may be associated with engine 12 to aid in the production of power by pressurizing a stream of fuel for subsequent production. Fuel pump 18 may be a swash plate pump, having a rotating cylinder (not shown) containing pistons (not shown). A spring (not shown) may force the pistons against a swash plate (not shown), the swash plate being oriented at an angle to the pistons. As the swash plate rotates relative to the pistons, the pistons receive fluid during the first half of each revolution and force fluid out at an elevated pressure during the second half. The swash plate angle may be varied, with the amount of fuel transferred increasing as the angle of the swash plate increases. Since the moving parts of fuel pump 18 bear against each other, causing metal- on-metal contact, lubrication thereof may be necessary to prevent excessive wear and tear of these parts. Lubrication system 14 may provide this lubrication. A turbocharger 20 may also be associated with engine 12 to facilitate the combustion process by pressurizing air directed into engine 12. Turbocharger 20 may include a turbine 19 and a compressor 21. Turbine 19 may receive exhaust gases from engine 12, causing turbine 19 to rotate. The rotation of turbine 19 may drive compressor 21, with compressor 21 operating to compress ambient air and deliver it to an air intake of engine 12. This delivery of compressed air may overcome a natural limitation of combustion engines by eliminating an area of low pressure within the engine combustion chambers created by a downward stroke of the pistons. Therefore, turbocharger 20 may increase the volumetric efficiency within the combustion chamber. This efficiency may allow more fuel to be burned, resulting in a larger power output. Both turbine 19 and compressor 21 of turbocharger 20 contain moving parts (e.g. impellers, shafts, bearings) that cause metal-on-metal contact as they move. Lubrication system 14 may provide oil to these bearing surfaces, thereby avoiding excessive wear and tear during engine operation.

As discussed above, lubrication system 14 may supply lubrication fluid to the bearing surfaces of engine 12 and other engine-driven parts (e.g. fuel pump 18, turbocharger 20, etc.) to avoid excessive wear and tear that results from un- lubricated metal-on-metal contact. Lubrication system 14 may include both a primary lubrication circuit 13 and a pre-lubrication circuit 15.

Primary lubrication circuit 13 may include a pump 22, a sump 24, a check valve 32, and a number of passageways. The purpose of primary lubrication circuit 13 may be to provide lubrication to power system 10 while engine 12 is operational. Pump 22 may be a typical pump known in the art and connected, for example, to be driven by the crankshaft of engine 12. Pump 22 may be a piston type pump, an impeller type pump, or any other type of pump known in the art. Pump 22 may draw fluid from sump 24, pressurize the fluid, and discharge the pressurized fluid into a passageway 30. Pump 22 may repeat this cycle, continuously pumping lubricant through primary lubrication circuit 13 during the operation of engine 12.

Sump 24 may be any metallic or polymeric chamber known in the art for holding a lubrication fluid. For example, sump 24 may be located at a bottom portion of engine 12 and function as a reservoir for lubrication system 14. Lubrication system 14 may both begin and end at sump 24. Lubrication fluid may be drawn from sump 24 at a beginning of lubrication system 14 and trickle down through engine block 11 under gravity to be collected in sump 24 at an end of lubrication system 14.

Check valve 32 may be located downstream from pump 22 to ensure a unidirectional flow of the lubrication fluid. Check valve 32 may be any type of check valve known in the art, including a ball check valve. A ball check valve may include a ball (not shown) seated on a bearing surface (not shown) and connected to a spring (not shown). Check valve 32 may prevent lubricant from flowing back into pump 22 during periods of time when pump 22 is not operating.

A passageway 26 and a passageway 28 may fluidly connect sump 24 to pump 22. A passageway 30 may connect pump 22 to check valve 32. A passageway 34 and a passageway 36 may fluidly connect check valve 32 to fuel pump 18. A passageway 38 may fluidly connect fuel pump 18 to turbocharger 20. From turbocharger 20, a passageway 40 may provide a fluid connection to engine 12 and terminate in sump 24, thereby completing the flow path of primary lubrication circuit 13. The passageways described above may consist of any metallic or polymeric conduit known in the art for transporting lubrication fluid under pressure.

Pre-lubrication circuit 15 may include a pump 42, a check valve 48, and a number of passageways. The purpose of pre-lubrication circuit 15 may be to provide lubrication to power system 10 prior to the ignition of engine 12. Pump 42 may be driven by a means other than engine 12, such as by an electric power source. It is contemplated that engine 12 may charge the electric power source during operation, if desired. Pump 42 may be a piston or impeller type pump, similar to pump 22 described above. Pump 42 may provide pressurized lubrication flow within pre-lubrication circuit 15. Like check valve 32 described above, check valve 48 may also be a ball type check valve. Check valve 48 may prevent lubricant from flowing back into pump 42 during periods of time when pump 42 is not operating.

The passageways of pre-lubrication circuit 15 may fluidly connect pump 42, sump 24, engine 12, and other engine-driven components. Pre- lubrication circuit 15 and primary lubrication circuit 13 may have passageways in common. Specifically, passageway 26 may communicate with a passageway 44 to fluidly connect sump 24 with pump 42. A passageway 46 may connect pump 42 to check valve 48. A passageway 50, together with passageway 36, may fluidly connect check valve 48 to fuel pump 18.

Starting control system 16 may include a controller 52 (i.e. an engine control unit~ECU), a pressure sensor 54, and an operator interface 56. Controller 52 may be any type of programmable logic controller known in the art for automating machine processes. Controller 52 may be made from any material known in the art for logic control devices, and may include a protective housing of metal, plastic, or another durable material. Controller 52 may include input/output arrangements that allow it to be connected to sensor 54, operator interface 56, and pump 42. Controller 52 may rely upon digital or analog means for processing input from operator interface 56 and pressure sensor 54 to create output for controlling engine 12 and pump 42. Controller 52 may communicate with the various components of starting control system 16 through a number of electrical lines. For example, an electrical line 62 may connect controller 52 to pressure sensor 54. An electrical line 64 may provide an electrical connection between controller 52 and pump 42. Two electrical lines 66 and 68 may connect controller 52 to operator interface 56. Controller 52 may therefore be capable of processing and executing an operator's command to start pre-lubrication and engine 12.

Pressure sensor 54 may be any type of sensor known in the art and capable of measuring a fluid pressure at a specific location, such as a mechanical deflection sensor. A mechanical deflection sensor may include a housing (not shown) containing a spring (not shown), where the pressure being measured causes a deflection of the spring. The amount of spring deflection may be calibrated to correspond to a given pressure. Pressure sensor 54 may be located at an outlet of engine 12 (i.e. an inlet of sump 24) along passageway 40, functioning to measure the pressure of lubrication fluid at that location. Sensor 54 may provide a signal indicative of this pressure as an input to controller 52, which may use the information in controlling power system 10.

Operator interface 56 may include an ignition input 58 and a warning device 60. Ignition input 58 may be any type of device known in the art for allowing an operator to provide an input to controller 52 indicative of a desire to start engine 12. For example, ignition input 58 may be a key-operated ignition switch that allows an operator to turn the switch between various settings, including an "on" setting, and an "off setting. Warning device 60 may be any type of device known in the art for signaling a fault condition to an operator, such as a warning light or audible warning sound. Warning device 60 may alert the operator to an abnormal or undesired lubrication status of power system 10.

Starting control system 16 may be capable of inhibiting the starting of engine 12 through ignition input 58 and controller 52. An operator may set ignition input 58 to the "on" setting, causing electrical lines 64 and 66 to signal controller 52 to start pump 42 and the pre-lubrication of power system 10. During this pre-lubrication period, controller 52 may maintain control of pump 42, pressure sensor 54, and engine 12 through electrical lines 62 and 64. The processing means of controller 52 described above may be programmed to create an output to engine 12 contingent upon input from pressure sensor 54. Therefore, controller 52 may be programmed to send an output to start ignition of engine 12, but only if sensor 54 has provided an input to controller 52 that adequate pre- lubrication has been measured. Accordingly, controller 52 may prevent the starting of engine 12 until power system 10 has attained an adequate level of pre- lubrication, as sensed by pressure sensor 54. Additionally, controller 52 may be programmed to allow the operator, through an input from operator interface 56 to controller 52, to start engine 12 at any time, even in the absence of an adequate pressure level reading from sensor 54.

Industrial Applicability

The disclosed lubrication system may help protect an associated engine by ensuring adequate pre-lubrication of the engine and engine-driven components, thereby avoiding excessive wear and tear caused by the metal-on- metal contact of un-lubricated parts. In particular, the disclosed lubrication system may help ensure pre-lubrication by preventing ignition of the engine until a sensor reports that a lubrication fluid pressure in the engine and critical engine- driven components has reached an adequate level.

Lubrication system 14 may operate either manually or automatically. Referring to Fig. 1 , manual operation will be described first. An operator may manually begin the pre-lubrication process through ignition input 58. Ignition input 58 may provide input to controller 52 to initiate only the pre- lubrication process. Engine 12 may remain turned off at this time. Controller 52 may then initiate the start of pump 42. Pump 42 may draw lubrication fluid under pressure out of sump 24, through passageways 26 and 44, and into pump 42. Pump 42 then pushes the fluid under pressure through passageway 46, check valve 48, and into passageway 50. Pump 42 may push fluid through passageway 36 and into fuel pump 18 to lubricate the moving parts of fuel pump 18. The pressure created by pump 42 may then push the fluid through passageway 38 and into turbocharger 20 to lubricate the moving parts of turbocharger 20. Pressure then pushes the lubrication fluid through passageway 40 and into engine 12, where the fluid may lubricate moving engine parts. Finally, under gravity, the lubrication fluid may trickle toward the bottom of engine 12 and into sump 24. The lubrication cycle repeats as pump 42 continues to draw lubrication fluid under pressure from sump 24.

Pump 42 may pressurize pre-lubrication circuit 15 until the pressure at sensor 54 reaches a pre-determined threshold. This threshold may correspond to the lubrication fluid pressure necessary to ensure adequate pre- lubrication of power system 10. When sensor 54 reports that the pressure in engine 12 is adequate, then the pressure in fuel pump 18 and turbocharger 20 must also be adequate, because fuel pump 18 and turbocharger 20 are located downstream from pump 42 and upstream from engine 12. In other words, upstream components attain adequate lubrication before components located further downstream. Once pressure sensor 54 measures an adequate pressure, it may report this condition to controller 52. Controller 52 may then report this condition to warning device 60, signaling to the operator that pre-lubrication is complete. The operator may then utilize ignition input 58 to signal to controller 52 that starting engine 12 should commence. When engine 12 starts, engine- driven pump 22 may also start pressurizing fluid, thereby beginning the operation of primary lubrication circuit 13. At substantially the same time, controller 52 may signal pump 42 to shut down, ending the operation of pre-lubrication circuit 15.

Pump 22 may draw lubrication fluid under pressure out of sump 24, through passageways 26 and 28, and into pump 22. Pump 22 may then push the fluid under pressure through passageway 30, check valve 32, and into passageway 34. Lubricant may then flow back to sump 24 in the same manner described above for pre-lubrication circuit 15. Primary lubrication circuit 13 may operate for as long as engine 12 remains operational, with pump 22 drawing lubrication fluid under pressure from sump 24. The operator may provide an input to controller 52, through ignition input 58, to shut down engine 12. Upon receiving this input, controller 52 may send an output to engine 12 to shut off, thereby ending the operation of power system 10. Referring to Fig. 1 , automatic operation will now be described.

The process is the same as set forth above for manual operation, except for the steps concerning ignition input 58 and controller 52. An operator may begin automatic operation through ignition input 58. Ignition input 58 may signal controller 52 that an operator desires ignition of engine 12. In response to the signal from ignition input 58, controller 52 may then initiate the start of pump 42, with engine 12 remaining shut off (i.e. being inhibited from starting). Pump 42 may pressurize pre-lubrication circuit 15 until pressure sensor 54 measures an adequate pressure, as explained above.

Once sensor 54 measures an adequate pressure, it may report the condition to controller 52. Controller 52 may then automatically start engine 12 and subsequently pump 22, thereby beginning the operation of primary lubrication circuit 13. Controller 52 may also automatically shut down pump 42, thereby ending the operation of pre-lubrication circuit 15. Primary lubrication circuit 13 may continue to operate as long as engine 12 remains operating. The operator may then shut down power system 10 in the same manner described above for manual operation.

Several advantages may be associated with power system 10. The first advantage is that pressure sensor 54 may help ensure that all critical engine- driven components are adequately lubricated prior to the ignition of engine 12. Since critical engine-driven components such as fuel pump 18 and turbocharger 20 are located downstream of oil pumps 22 and 42, but upstream of sensor 54 and engine 12, sensor 54 may ensure that these critical components will be lubricated and protected from wear and tear during ignition. Since sensor 54 operates by measuring a pressure in engine 12, sensor 54 has the capability of operating independently from a pre-set time period. Since sensor 54 relies on a direct pressure measurement, rather than indirectly on an arbitrary time period, adequate pre-lubrication is ensured. It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed pre-lubrication system. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed method and apparatus. For example, although described with respect to a fuel pump and a turbocharger, the disclosed pre-lubrication system could similarly protect other critical engine- driven components. Also, although described as being located upstream of the turbocharger, the fuel pump could just as easily be located downstream of the turbocharger. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.

Claims

1. A method of providing lubrication to an engine (12), comprising: drawing power from the engine (12) to pressurize lubricant at a first location; pressurizing the lubricant at a second location; passing the lubricant through an engine-driven component located upstream of the engine (12); passing the lubricant through the engine (12); and inhibiting engine ignition based on a pressure of the lubricant in the engine (12).

2. The method of claim 1 , further including measuring the pressure at an outlet of the engine (12).

3. The method of claim 1, wherein inhibiting includes automatically preventing engine ignition.

4. The method of claim 1, wherein inhibiting includes providing a warning to an operator of the engine (12) to postpone starting when the pressure is below a predetermined threshold.

5. The method of claim 1, wherein lubricant at the second location is pressurized by a power source independent from engine operation.

6. A power system (10), comprising: an engine (12); a first pump (22) driven by the engine (12) to lubricate the engine (12); a second pump (42) configured to lubricate the engine (12); a component driven by the engine (12) and fluidly connected downstream of the second pump (42) and upstream of the engine (12); and a sensor (54) located at the engine (12) to generate a signal indicative of an engine lubrication status, wherein starting of the engine (12) is inhibited based on the engine lubrication status.

7. The power system (10) of claim 6, wherein the sensor (54) is located at an outlet of the engine (12).

8. The power system (10) of claim 7, further including a controller (52) in communication with the sensor (54) and being configured to prevent starting of the engine (12) when a pressure of the lubrication at the outlet of the engine (12) is below a predetermined pressure.

9. The power system (10) of claim 7 further including a controller (52) in communication with the sensor (54) and being configured to warn an operator of the engine (12) to postpone starting the engine (12) when a pressure of the lubrication at the outlet of the engine (12) is below a predetermined pressure.

10. The power system (10) of claim 6, further including a first check valve (32) located downstream of the first pump (22), and a second check valve (48) located downstream of the second pump (42), both the first and second check valves being located upstream of the component.