Turbocharger Oil Supply Passage Check Valve And Method

Abstract

A turbocharger (500) for an internal combustion engine (400) includes a center housing (504) having an oil supply passage (412) in fluid communication with an oil pump (404). The oil pump (404) is in fluid communication with an oil reservoir (420) in the engine (400). An oil drain passage (418) is also in fluid communication with the oil reservoir (420). A check valve (401) is in fluid communication with the supply passage (412) and located between the oil pump (404) and the center housing (504) of the turbocharger (500) to prevent oil from passing from a portion of the oil supply passage (424) back to the oil pump (404).

Description

FIELD OF THE INVENTION

[0001] This invention relates to turbochargers, including but not limited to turbochargers for internal combustion engines.

BACKGROUND OF THE INVENTION

[0002] Some internal combustion engines use turbochargers and other devices to improve their performance. A typical turbocharger includes a turbine, which is driven by exhaust gas, connected to a center housing, which in turn is connected to a compressor. A shaft running through the turbocharger has a wheel attached on either end. The shaft rotates during operation of the turbocharger requiring lubrication.

[0003] Lubrication for the turbocharger shaft is typically accomplished in the center housing by a flow of oil from the engine passing there through. The flow of oil usually is supplied by an oil pump attached to the engine. A series of tubes and passages usually fluidly connect an outlet of the oil pump with an inlet in the center housing. Oil drains from the center housing back into the engine.

[0004] When the engine is not operating, the oil pump is not supplying oil to the center housing of the turbocharger, and all if not most of the oil in the center housing has drained into the engine. When the engine is first turned on, the turbocharger shaft begins to rotate through the action of exhaust gas coming from the engine. As the engine begins to operate, the oil pump also begins to pump oil to various engine components, including the turbocharger. There is a lag time for oil from the oil pump to reach and lubricate the rotating shaft in the center housing of the turbocharger. This time lag may be attributed, in part, to factors such as the time required to prime the oil pump, travel time through the various tubes and passages connecting the oil pump and the center housing for the initial flow of oil, or high oil viscosity due to cold engine operation. During this lag time, the shaft in the center housing is rotating without lubrication. This operation of the shaft without lubrication may cause scuffing of bearings attached thereon.

[0005] There have been various methods in the past addressing the issue of inadequate lubrication of a turbocharger at engine startup. One such example is an engine configuration shown in U.S. Pat. No. 6,745,568 by Squires, published Jun. 8, 2004. Squires teaches a turbocharger lubrication system with an inlet in fluid communication with an oil pump, having a pressure driven check valve that prevents oil from flowing into the turbocharger when the pressure of oil coming from the oil pump is less than 5 psi. The check valve taught in Squires may work well in lubricating the turbocharger at engine startup with oil in the turbocharger supply passage, but also introduces a pressure drop in the lubrication system of the turbocharger of at least 5 psi. This additional pressure drop in the turbocharger lubrication system is detrimental to the operation of the lubrication system at times when pressure in the lubrication system is low. Moreover, lubrication to the turbocharger is essentially disabled when oil pressure in the lubrication circuit is below 5 psi. Additionally, oil may pass through the check valve once an adequate pressure has accumulated upstream of the check valve, in this case a pressure of above 5 psi, which may introduce a delay in the time required for lubrication of the turbocharger after the engine is in operation.

[0006] Accordingly, there is a need for ensuring that adequate lubrication is available for a turbocharger shaft under conditions of initial engine startup or cold engine operation, without adding an additional pressure drop to an oil lubrication system, and that ensures that lubrication to the turbocharger is immediately available for all lubrication system operating pressures when the engine is in operation.

SUMMARY OF THE INVENTION

[0007] To avoid potential issues associated with operating a turbocharger without an adequate supply of oil for lubrication when an engine is first turned on, or, when an engine is operating under cold conditions, a check valve is added to a turbo oil supply passage. A turbocharger for an internal combustion engine includes a center housing having an oil supply passage in fluid communication with an oil pump. The oil pump is in fluid communication with an oil reservoir in the engine. An oil drain passage is also in fluid communication with the oil reservoir. A check valve is in fluid communication with the supply passage and located between the oil pump and the center housing of the turbocharger to prevent oil from passing from a portion of the oil supply passage back to the oil pump.

[0008] A method for operating an engine having a turbocharger includes the step of collecting oil in an internal volume of an internal combustion engine. Oil from the engine internal volume is pumped with an oil pump. Pumped oil flow is supplied to a center housing of a turbocharger through an oil supply passage when the internal combustion engine is operating. Oil from the center housing is drained into the engine internal volume. A quantity of oil in the oil supply passage is maintained between the center housing of the turbocharger and a check valve when the engine is not in operation. The check valve is located between the center housing of the turbocharger and the oil pump.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a block diagram of an engine having a turbocharger.

[0010] FIG. 2 is a block diagram of an oil circuit for an internal combustion engine in accordance with the invention.

[0011] FIG. 3 is a block diagram of an engine having a turbocharger with a check valve in accordance with the invention.

[0012] FIG. 4 is a view of an turbocharger oil supply passage with a fitting having a check valve in accordance with the invention.

[0013] FIGS. 5-8 are cross section views of various fittings, each having an integrated check valve in accordance with the invention.

[0014] FIG. 9 is a flowchart for a method of operating an engine having a turbocharger in accordance with the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

[0015] The following describes an apparatus for and method of ensuring that adequate lubrication is available for a turbocharger shaft under conditions of initial engine startup or cold engine operation. A typical diesel engine configuration having a turbocharger is shown in FIG. 1. An engine 100 may include a crankcase 102, which may contain an oil pump 104, a sump feed 106, and an oil cooler feed 108. The engine 100 may additionally have an oil cooler 110, an optional component, connected to a turbocharger oil supply line 112. During operation of the engine 100, oil may be drawn to the pump 104 through the sump feed 106 that may be submerged in an oil pool 114 collected in an oil pan 116 that is connected to the crankcase 102. The pump 104 will push oil into the oil cooler feed 108. Oil entering the oil cooler 110 may be distributed to many areas and components of the engine 100 for cooling and lubrication of the engine 100 as is known in the art. A portion of the oil flow exiting the oil cooler 110 may be routed to the turbocharger oil supply line 112. Oil flow in the oil supply line 112 may enter a turbocharger 200 from an oil inlet 208 to the center housing 204 discussed above. The turbocharger 200 may be connected to the engine 100, but is shown above the engine 100 for the sake of clarity concerning oil connections.

[0016] Oil flow exiting the center housing 204 from an oil outlet 210 is collected in an oil drain line 118. The oil drain line 118 fluidly connects the center housing 204 with an internal volume 120 of the crankcase 102. Oil exiting the drain line 118 may be allowed to pour into the internal volume 120 through a convenient location, for example, a valve cover 122, and collect under the force of gravity into the oil pan 116. Oil is compelled to flow through the center housing 204 because of a pressure difference between a high pressure P1 generated by the pump 104 and a low pressure P2 of the air inside the crankcase 102. The high pressure P1 is an outlet oil pressure within the oil cooler feed 108 that may be within a range of about 12 to 30 PSI (83 to 207 kPa) during normal operation of a warm engine, and may reach pressures up to 150 PSI (1 MPa) under cold engine conditions. The gas pressure P2 within the crankcase 102 of the engine 100 may be between about 3 to 10 inches of Mercury (10 to 34 kPa) during normal operation.

[0017] When the engine 100 is not operating, oil anywhere along a supply path connecting the outlet 108 of the oil pump 104 with the inlet 208 of the center housing 204 may drain out. When the engine 100 is first turned on, oil must be drawn up the sump 106, through the pump 104, through the passage 108, through the cooler 110, and through the tube 112 before reaching the center housing 204. During this time, a shaft (not shown) rotating within the center housing 204 will be operating without lubrication. A typical engine may require 10 to 15 seconds or more, after starting, to supply a turbocharger with oil. During this time, scuffing may occur at an interface (not shown) between the shaft and bearings. This issue may be resolved, or its effects may be substantially alleviated, as described below.

[0018] A block diagram of an engine 300 having a turbocharger and a check valve is shown in FIG. 2. An oil reservoir 302 holds a quantity of oil. When the engine 300 operates, oil from the reservoir 302 is pulled into an oil pump 304. The oil pump 304 increases a pressure of oil passing through it, and pumps it to an oil cooler and/or and oil filter, collectively denoted with reference numeral 306 and shown in dashed line as optional. One portion of oil flow from the oil pump 304 is routed to other engine components, shown collectively as block number 308. These other engine components 308 may include for instance fuel injectors, crankshaft and/or camshaft bearings, piston cooling jets, and so forth. A second portion of oil flow from the oil pump 304 is routed to a check valve 310 valve 310 before being supplied to a turbocharger 312. Oil from the turbocharger 312 and the other engine components 308 drains back into the reservoir 302. The check valve 310 valve 310 is arranged to allow oil to flow in a direction toward the turbocharger 312, and prevent oil to flow back from the turbocharger 312 toward the oil pump 304. The valve 310 may be a unidirectional valve that opens immediately when flow from the oil pump to the turbocharger is initiated and present, and may close when a driving force, or pressure, causing the flow of oil from the oil pump to the turbocharger, ceases. Advantageously, the valve 310 may not have a minimum opening pressure required to open. The valve 310 may be a "zero" opening pressure check valve, or alternatively, may be an electronically controlled valve.

[0019] In the case when the valve 310 is a "zero" opening pressure valve, a gate member or plug (discussed below in the embodiments of FIGS. 5-8)

[0020] One embodiment of an engine 400 implementing a check valve 401 is shown in FIG. 3. The engine 400 may include a crankcase 402, which may contain an oil pump 404 having a sump feed 406 and an oil cooler feed 408. The engine 400 may additionally have an optional oil cooler 410 connected to a turbocharger oil supply line 412. The supply line 412 is connected to an input 508 on the turbocharger 500. The supply line 412 has a check valve 413 attached thereon between the oil pump 404 and a turbocharger 500. The turbocharger 500 may be connected to the engine 400, but is shown above the engine 400 for the sake of clarity concerning oil connections.

[0021] Oil flow exits a center housing 504 of the turbocharger 500 from an oil outlet 510, and is collected in an oil drain line 418. The oil drain line 418 fluidly connects the center housing 504 with an internal volume 420 of the crankcase 402. Oil exiting the drain line 418 may be allowed to pour into the internal volume 420 through a convenient location, for example, a valve cover 422, and collect under the force of gravity into an oil pan 416 and mix with an oil pool 414 collected therein. Oil is compelled to flow through the center housing 504 because of a pressure difference between a high pressure P1 generated by the pump 504 and a low pressure P2 of the air inside the crankcase 502. The high pressure P1 is an outlet oil pressure within the oil cooler feed 408 that may be within a range of about 12 to 30 PSI (83 to 207 kPa) during normal operation of a warm engine, and may reach pressures up to 150 PSI (1 MPa) under cold engine conditions. The gas pressure P2 within the crankcase 102 of the engine 400 may be between about 3 to 10 inches of Mercury (10 to 34 kPa) during normal operation.

[0022] When the engine 400 is not operating, oil present along a supply path connecting the outlet 408 of the oil pump 404 with the inlet 508 of the center housing 504 will advantageously not drain out completely. An amount of oil 424 is advantageously retained in a portion 426 of the line 418 by the check valve 401. The amount of oil 424 is adequate for lubrication of the center housing 504 for a limited time, typically about 10 to 15 seconds or until an oil flow from the pump 404 reaches the center housing 504 when the engine is first started. The check valve 401 is advantageously located above a level of oil in the oil pan 416. The amount of oil 424 in the supply passage portion 426 forms a column of oil of height, H, which exerts a hydrostatic pressure. This hydrostatic pressure, which is approximately equal to the height H multiplied by a density of engine oil, may be used to close the check valve 401 when the engine 400 is not operating. Alternatively, the check valve 401 may be closed by a spring or any other device known to be used for this purpose.

[0023] One example of an advantageous implementation of the embodiment of FIG. 3 is shown in FIG. 4. In this example, a partial view of a side portion of an engine 600 is shown. A turbocharger 602 has a center housing 604 with an oil inlet 606. The turbocharger 602 is connected to the engine 600. An oil cooler 608 is connected to the engine 600 below the turbocharger 602. A turbo supply tube assembly 610 includes an inlet fitting 612, a first tube section 614, a flexible section 616, a second tube section 618, and an outlet fitting 620. The inlet fitting 612 is connected to the engine 600 at an outlet of the oil cooler 608. The outlet fitting 620 is connected to the center housing 604 of the turbocharger 602. A check valve 622 is advantageously integrated with the inlet fitting 612. Almost an entire volume of the turbo oil supply tube assembly 610 may advantageously be used to collect an amount of oil to lubricate the turbocharger 602 when the engine 600 is first started.

[0024] One exemplary embodiment for an inlet fitting 700 having a check valve integrated therein is shown in a closed position in FIG. 5, and in an open position in FIG. 6. The fitting 700 includes a threaded nut 702. The nut 702 is adapted to thread onto a male piece (not shown) and secure a connector body 704 by pressing on a shoulder surface 706 of the body 704. The body 704 has a sealing surface 708 opposite the shoulder 706. The sealing surface 708 may have a sealing groove 710 formed therein and adapted to receive a seal (not shown) that will advantageously form a seal with the male piece. The sealing groove surrounds an inlet opening 711. The body 704 has a central chamber 712 that creates a passage 714 for fluid flow through the body 704. The chamber 712 has an entry socket seat 716 on one end of the passage 714 adjacent to the inlet opening 711, and an exit socket seat 718 on another end of the passage 714. The chamber 712 contains a spherical plug 720.

[0025] The inlet fitting 700 is shown in a closed position in FIG. 5. The plug 720 sits against the entry socket seat 716 substantially fluidly sealing and cutting off the passage 714. In a typical condition, an amount of oil rests above the plug 720. A force of gravity due to the weight of the plug 720, in addition to a hydrostatic pressure of the amount of oil resting above the plug 720 presses the plug 720 against the entry socket seat 716. When a flow of oil begins to flow through the inlet opening 711, for example when an engine is turned on and an oil pump begins to supply oil to a turbocharger through the fitting 700, a pressure of the flow of oil pushes the plug 720 off the entry socket seat 716 and against the exit socket seat 718, as shown in FIG. 6. The exit socket seat 718 is advantageously not continuous and has a plurality of openings 722 formed therein to allow the flow of oil to pass from the inlet opening 711, around the plug 720, through the openings 722, and exit the fitting 700 through an outlet opening 724 that is located at a distal end of the passage 714 opposite from the inlet opening 711.

[0026] The plug 720 will remain off the entry socket seat 716 and allow oil to flow through the fitting 700 while the engine is operating and the flow of oil is pushed through the fitting 700. When the flow of oil ceases, for example when the engine ceases to operate, the plug 720 will once more rest against the entry socket seat 716 thus trapping a quantity of oil above the plug 720 as described above.

[0027] Another exemplary embodiment for an inlet fitting 800 having a check valve integrated therein is shown in a closed position in FIG. 7, and in an open position in FIG. 8. The fitting 800 includes a threaded nut 802. The nut 802 is adapted to thread onto a male piece (not shown) and secure a connector body 804 by pressing on a shoulder surface 806 of the body 804. The body 804 has a sealing surface 808 opposite the shoulder 806. The sealing surface 808 may have a sealing groove 810 formed therein and adapted to receive a seal (not shown) that will advantageously form a seal with the male piece. The sealing groove surrounds an inlet opening 811. The body 804 has a central chamber 812 that is part of a passage 814, which allows for fluid flow through the body 804. The chamber 812 has an entry seat 816 on one end of the passage 814 adjacent to the inlet opening 811. The chamber 812 contains a flap 820 that is rotateably connected to the surface 816 and constructed to cover the opening 811 completely.

[0028] The inlet fitting 800 is shown in a closed position in FIG. 7. The flap 820 sits against the entry seat 816 substantially fluidly sealing and cutting off the passage 814. In a typical condition, an amount of oil rests above the flap 820. A force of gravity due to the weight of the flap 820, in addition to a hydrostatic pressure of the amount of oil resting above the flap 820 presses the flap 820 against the entry seat 816. When a flow of oil begins to pass through the inlet opening 811, for example when an engine is turned on and an oil pump begins to supply oil to a turbocharger through the fitting 800, a pressure of the flow of oil pushes the flap 820 off the entry seat 816 and into the chamber 812, as shown in FIG. 8. The flow of oil passes from the inlet opening 811, around the flap 820, and exits the fitting 800 through an outlet opening 824 that is located at a distal end of the passage 814 opposite from the inlet opening 811.

[0029] The flap 820 will remain off the entry seat 816 and allow oil to flow through the fitting 800 while the engine is operating and the flow of oil is pushed through the fitting 800. When the flow of oil ceases, for example when the engine ceases to operate, the flap 820 will once more rest against the entry seat 816 thus trapping a quantity of oil above the plug 820 as described above.

[0030] Other types or designs of check valves known in the art may be used in addition or in place to the ones described herein.

[0031] A flowchart for a method of operating a turbocharger is shown in FIG. 9. Oil is collected in an internal volume of an internal combustion engine at step 902. A quantity of oil is pumped from the engine internal volume with an oil pump at step 904 when the engine is operating, and sent to various engine components. A pumped oil flow exiting the oil pump is supplied to a center housing of a turbocharger through an oil supply passage at step 906 and while the internal combustion engine is still operating. Oil from the center housing is drained back into the engine internal volume at step 908. A quantity of oil is maintained in the oil supply passage between the center housing of the turbocharger and a check valve, the check valve fluidly connected to the oil supply passage and located between the center housing of the turbocharger and the oil pump at step 910 and when the engine is not in operation.

[0032] The check valve may be opened when the engine is in operation to allow the flow of oil to reach the center housing of the turbocharger. The quantity of oil maintained in the oil supply passage when the engine is not in operation may advantageously be adequate for lubrication of the center housing for a period of time, for example 10 seconds or more, after the engine is in operation. Further, the quantity of oil in the supply passage may form a column of oil which may advantageously exert a hydrostatic pressure that closes and/or helps seal the check valve.

[0033] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A turbocharger for an internal combustion engine comprising: a center housing connected to a turbine housing and a compressor housing; an oil supply passage in fluid communication with an oil pump, wherein the oil pump is in fluid communication with an oil reservoir; an oil drain passage in fluid communication with the oil reservoir; and a check valve disposed in fluid communication with the supply passage between said oil pump and the center housing of said turbocharger to prevent oil from passing from a portion of the oil supply passage to the oil pump.

2. The turbocharger of claim 1, wherein the check valve is integrated into a fluid coupling, wherein the oil supply passage is a tube, and wherein the coupling is disposed at a distal end of the tube.

3. The turbocharger of claim 1, wherein an amount of oil is disposed in the portion of the oil supply passage when the engine is not operating, wherein the amount of oil in the portion of the supply passage is adequate for lubrication of the center housing for a limited time, and wherein the limited time is adequate for the oil pump to supply oil to the supply passage when the engine is first started.

4. The turbocharger of claim 1, wherein the check valve is disposed above the level of oil reservoir.

5. The turbocharger of claim 1, further comprising an oil cooler disposed between the oil pump and the check valve.

6. The turbocharger of claim 1, wherein the check valve includes a plug disposed in a chamber, and wherein the plug is pressed against a seat when the check valve is closed.

7. The turbocharger of claim 1, wherein the check valve includes a flap disposed in a chamber, and wherein the flap is pressed against a substantially flat surface when the check valve is closed.

8. A method for operating an engine having a turbocharger, comprising the steps of: collecting oil in an internal volume of an internal combustion engine; pumping oil from the engine internal volume with an oil pump; supplying pumped oil flow to a center housing of a turbocharger through an oil supply passage when the internal combustion engine is operating; draining oil from the center housing into the engine internal volume; and maintaining a quantity of oil in the oil supply passage between the center housing of the turbocharger and a check valve, the check valve disposed between the center housing of the turbocharger and the oil pump, when the engine is not in operation.

9. The method of claim 8, further comprising the step of cooling the pumped oil flow.

10. The method of claim 8, opening the check valve when the engine is in operation.

11. The method of claim 8, wherein quantity of oil maintained in the oil supply passage is adequate for lubrication of the center housing for a period of time after the engine is in operation.

12. The method of claim 8, wherein the step of maintaining a quantity of oil in the oil supply passage is accomplished by closing the check valve when the engine is turned off, wherein the quantity of oil in the supply passage forms a column of oil which exerts a hydrostatic pressure, and wherein the check valve is closed by the hydrostatic pressure.

13. The method of claim 12, wherein the step of closing the check valve includes at least one of sinking a plug in a chamber and pressing a flap against a surface.

14. An internal combustion engine comprising: an engine structure having an internal volume including an oil reservoir, wherein an amount of oil is collected in an oil pool in the reservoir; a turbocharger mounted to said engine structure and having a center-housing connected to a turbine housing and a compressor housing, wherein the center-housing includes an oil supply passage and an oil drain passage, in fluid communication with the oil cavity; an oil pump in fluid communication with the oil supply passage and the oil pool; a check valve fluidly connecting the oil supply passage with the oil pump, wherein the check valve is arranged to prevent oil flow from the oil supply passage in the center-housing to the oil pump; and a quantity of oil disposed between the check valve and the center housing when the engine is not in operation, wherein the quantity of oil is sufficient to lubricate the center housing when the engine is first operated.

15. The internal combustion engine of claim 14, wherein the oil drain passage is in fluid communication with the oil reservoir.

16. The internal combustion engine of claim 14, wherein the quantity of oil is disposed in an oil supply tube, and wherein the quantity of oil in the oil supply tube forms a standing column of fluid that exerts a hydrostatic pressure on the check valve.

17. The internal combustion engine of claim 14, further comprising an oil cooler in fluid communication with the oil pump and the oil supply passage.

18. The internal combustion engine of claim 14, wherein the check valve is integrated with an oil supply tube, said oil supply tube fluidly connecting the oil pump with the oil supply passage in the center housing of the turbocharger.

19. The internal combustion engine of claim 14, further comprising an oil cooler disposed between the oil pump and the check valve.

20. The internal combustion engine of claim 19, further comprising an oil filter disposed between the oil cooler and the check valve.