A METHOD AND AN APPARATUS FOR CLEANING INTERNAL COMBUSTION ENGINE CRANKCASE BLOW-BY GAS AND AN INTERNAL COMBUSTION ENGINE INCLUDING SAID APPARATUS

Abstract: A method and an apparatus for reducing oil content of blow-by gas in an internal combustion engine. The method includes conveying the blow-by gas (34) away from the engine to be cooled in a heat exchanger (30), for example. Oil (40) condensing from the cooled blow-by gas (34) is returned to the engine and the cooled blow-by gas is exhausted to atmosphere or conveyed to the engine air intake system.

Description: A METHOD AND AN APPARATUS FOR CLEANING INTERNAL COMBUSTION ENGINE CRANKCASE BLOW-BY GAS AND AN INTERNAL COMBUSTION ENGINE INCLUDING SAID APPARATUS The present invention relates to a method and an apparatus for cleaning internal combustion engine crankcase blow-by gas and an internal combustion engine including said apparatus. During the compression and power strokes in an internal combustion engine, the difference in gas pressures above and below a piston is sufficient to cause leakage (blow-by) of gas past the piston into the engine crankcase. The resulting increase in pressure within the crankcase can cause oil to pass by the engine oil seals and this pressure may also damage the seals. To diminish the damaging effects of blow-by it is normal to relieve crankcase pressure by either venting the blow-by gas to atmosphere via an open breather or by connecting the crankcase to the engine intake air system whereby blow-by gas is conveyed to the air intake system and thence to the combustion chamber under the control of a pressure regulating valve. The pressure regulating valve maintains gas pressure within the crankcase between desirable limits. This latter arrangement constitutes a closed-circuit breather system. The blow-by gas carries with it oil vapour and this exits the engine to atmosphere via the open breather or, in the closed-circuit breather system, is taken into the engine air inlet system and is partially or fully burned before exiting to atmosphere via the engine exhaust system. In either case, this results in undesirable emissions being emitted which contain either unburned oil or the products of burned oil. The oil content of the blow-by gas, where this is fed into the engine intake air system via a closed-circuit breather system, also leads to fouling of turbo-charger compressor vanes, engine poppet valves and other components in contact with inlet air. It is an object of the present invention to provide a method of reducing oil content of blow-by gas in an internal combustion engine. It is a further object of the present invention to provide an apparatus for reducing oil content of blow-by gas in an internal combustion engine. A yet further objective is to provide a means for the recovery of lubricating oil which would otherwise be lost to atmosphere or burned in the engine combustion chamber. According to one aspect of the present invention, there is provided a method of reducing oil content of blow-by gas in an internal combustion engine, comprising the steps of : conveying blow-by gas away from the engine crankcase; cooling said blow-by gas; returning oil condensed from said cooled blow-by gas to the engine; and conveying said cooled blow-by gas to atmosphere or to the engine air intake system. The method may include the step of using a heat exchanger to cool the blow-by gas. The method may also include the step of using air from the engine air intake system to cool the blow-by gas. The method may include the step of returning oil condensed from said cooled blow-by gas to the engine sump. The method may include the step of conveying the cooled blow-by gas to the engine air intake system on an engine side of an air filtering means of said air intake system. According to a second aspect of the present invention, there is provided an apparatus for reducing oil content of blow-by gas in an internal combustion engine, the apparatus comprising : means for conveying blow-by gas away from the engine crankcase; means for cooling said blow-by gas; means for returning oil condensed from the cooled blow-by gas to the engine and means for conveying said cooled blow-by gas to atmosphere or to the engine air intake system. The means for conveying blow-by gas away from the engine crankcase may comprise the means for cooling said blow-by gas. Alternatively, the cooling means may comprise a heat exchanger cooled by any suitable cooling agent. The heat exchanger may be arranged such that it uses air from the engine air intake system as the cooling agent. The heat exchanger may be arranged such that the blow-by gas flows through said heat exchanger in a direction generally opposite to a direction of flow of the cooling agent. The heat exchanger may be arranged such that the length of a flow path of blow-by gas through the heat exchanger is substantially greater than the length of a flow path through said heat exchanger of the cooling agent. The heat exchanger may be arranged such that the cooled blow-by gas passes into the engine air intake system via the heat exchanger. The heat exchanger may be arranged such that the cooled blow-by gas passes into the engine air intake system on an air intake system inlet side of said heat exchanger. The heat exchanger may be arranged on an engine side of an air filtering means of the engine air intake system. The heat exchanger may comprise a housing containing at least one tubular member arranged with its longitudinal axis parallel with the longitudinal axis of the housing, said at least one tubular member defining a flow path for the cooling agent, an inlet for blow-by gas which communicates with space surrounding said at least one tubular member and partition plates which divide said space to define a flow path for the blow-by gas extending from said blow-by gas inlet to a blow-by gas outlet of the heat exchanger. Preferably, the heat exchanger includes a plurality of tubular members arranged spaced apart in side-by-side relationship within the housing. The tubular members may be circular in cross- section. Each tubular member may include a fin extending from its outer surface, the fin acting as an additional heat transfer means for cooling the blow- by gas. Alternatively, the tubular members may have a polygonal cross-section. The heat exchanger may include a meshed material located adjacent at least the blow-by gas outlet. The heat exchanger may include blow-by gas pressure regulating means. According to a third aspect of the present invention there is provided an internal combustion engine incorporating an apparatus in accordance with the next sixteen preceding paragraphs. The foregoing and further features of the present invention will be more readily understood from the following description of preferred embodiments, by way of example thereof, with reference to the accompanying drawings, of which: Figure 1 is a schematic illustration of an internal combustion engine including an apparatus in accordance with a first embodiment of the present invention; Figure 2 is a schematic illustration of an internal combustion engine including an apparatus in accordance with a second preferred embodiment of the present invention; Figure 3 is a longitudinal-sectional view in a vertical plane of a heat exchanger for use in the apparatus of the second embodiment of the invention; Figure 4 is a cross-sectional view on vertical section line A-A of figure 3 illustrating the arrangement of tubular members within a housing of the heat exchanger; Figure 5 is a cross-sectional view on vertical section line A-A of figure 3 showing a similar arrangement to that of figure 4 of alternative tubular members within the housing of the heat exchanger; Figures 6a to c are plan views of partition plates for the heat exchanger of figure 3 incorporating the tubular member arrangement of figure 5; Figure 7 is a longitudinal-sectional view in a vertical plane of a second embodiment of a heat exchanger; Figure 8 is a longitudinal-sectional view in a vertical plane of a third embodiment of a heat exchanger; Figure 9 is a schematic illustration of an internal combustion engine including an apparatus in accordance with a third embodiment of the present invention; and Figure 10 is a side elevational view of reduced scale of the engine and blow-by gas cleaning apparatus of figure 9. Referring to the drawings, figure 1 is a schematic illustration of an internal combustion engine 10 including an apparatus 12 for cleaning crankcase blow-by gas in accordance with a first embodiment of the invention. The internal combustion engine 10 is of the overhead camshaft type and has a crankcase 14, an oil sump 16, an inlet air manifold 18 for conveying air to a combustion chamber 20 disposed above a piston 22, an exhaust manifold 24 for conveying exhaust gas away from said combustion chamber 20 and a rocker arm housing 26 containing a rocker arm and camshaft arrangement 28. The apparatus 12 for cleaning blow-by gas comprises a heat exchanger 30 located in the engine air intake system with its air outlet 30a connected to the engine air manifold 18 and its inlet 30b connecting with an outlet of an air filtering means (not shown) of said air intake system. The apparatus 12 also includes a pipe 32 for conveying blow-by gas 34 from the engine crankcase 14 to a blow-by gas inlet 30c of the heat exchanger 30 and an oil return pipe 36 connecting the oil sump 16 with an oil outlet 30d of said heat exchanger 30. The heat exchanger 30 also includes a blow-by gas outlet 30e. During engine operation, oil within the engine sump 16 becomes hot and due to mechanical agitation by rotation of the crankshaft 38 some of the oil exists as a hot mist/vapour coating engine components within the crankcase 14 and contaminating blow-by gas which leaks into the crankcase 14. The blow-by gas increases pressure within the crankcase 14 and ordinarily this pressure would be released by exhausting the gas to atmosphere through an open breather or alternatively conveying said gas to the engine air inlet manifold under the control of a pressure regulating means. In the present invention, the blow-by gas from the crankcase 14 is conveyed to the heat exchanger 30 where it is cooled. Cooling of the blow-by gas causes some of the oil vapour contained therein to condense and the condensed oil 40 is collected and returned to the engine 10. The oil 40 is returned to the engine sump 16 by the oil return pipe 36 and enters said sump 16 below the oil level 42. The "cleaned" blow-by gas is exhausted to atmosphere. It will be appreciated that the heat exchanger 30 can be cooled by any suitable cooling agent, but it is preferred that the heat exchanger 30 is cooled by air 42 from the engine air inlet system thus providing a simple and inexpensive method of cooling the blow-by gas. Figure 2 is a schematic illustration of an internal combustion engine including an apparatus in accordance with a second preferred embodiment of the present invention. In the following description, like numerals will be used to denote like parts. This embodiment differs from that illustrated in figure 1 insofar that the blow-by gas outlet 30e of the heat exchanger 30 is internal to the heat exchanger 30 and directs cooled blow-by gas into the engine inlet air flow. Thus, the blow-by gas once cleaned is directed to the engine combustion 20 chamber for combustion of any oil remaining in the cooled blow-by gas and, equally importantly, combustion of any uncombusted fuel products contained within said gas. Thus, emissions from the engine 10 due to burning of oil contained within blow-by gas is dramatically reduced. Both of the embodiments hereinbefore described also have the advantage of recovering a substantial proportion of oil 40 which would ordinarily be lost in the blow-by gas. It has surprisingly been found that by cooling the blow-by gas in the manner proposed an oil recovery rate of up to 70% can be achieved. Figure 3 illustrates a preferred form of the heat exchanger 30 for use in the apparatus according to the invention. This comprises a generally cylindrical housing 44 containing a plurality of tubular members 46 which are arranged spaced apart in side-by-side relation with their longitudinal axes parallel with the longitudinal axis of the housing 44. The tubular members 46 are spaced within the housing 44 so as to provide gaps 48 (figures 4 and 5) therebetween and an outer space 50 (figures 4 and 5) between them and an inner wall 44a of the housing which together with partition plates 52(a,b,c) which divide the space 50 define a flow path for blow-by gas between the blow-by gas inlet 30c and blow-by gas outlet 30e of the heat exchanger 30. The tubular members 46 collectively define a flow path for the cooling agent which, in the preferred embodiment, comprises air from the engine inlet air system. In the preferred embodiment, it will be seen that blow-by gas 34 entering the blow-by gas inlet 30c of the heat exchanger 30 is forced to flow over the outer surfaces of first ends of the tubular members 46 generally downwardly before rising over second ends of the tubular members 46 towards the blow-by gas outlet 30e. The tubular members 46 are cooled by the air 42 from the engine inlet air system flowing through them. Consequently, the blow-by gas, which is at a temperature of approximately 70°C on entry to the heat exchanger 30, is cooled to about 20°C during its passage between the blow-by gas inlet 30c and outlet 30e. This results in a substantial proportion of oil vapour contained within said blow-by gas condensing within the housing 44. The condensed oil collects in a base of the housing 44 before draining via the oil drainpipe 36 back to the engine sump 16. The blow-by gas outlet 30e directs cooled blow-by gas into the inlet air flow to be carried to the engine inlet manifold for combustion. The heat exchanger is arranged such that blow-by gas is generally forced to flow in a direction opposite to that of cooling air from the engine inlet air system and the length of the blow-by gas flow path is substantially greater than the length of the flow path of cooling air from the engine air cooling system. The tubular members 46 may be circular (figure 4) in cross-section some of which may include a fin 46a to increase the heat transfer surface area of the blow-by gas flow path. Preferably, the tubular members 46 are hexagonal and are arranged such that the gaps 48 therebetween are of constant width thus defining a plurality of minor flow paths for blow-by gas. The partition plates 52(a,b,c) are arranged so as to secure the tubular members 46 in their spaced apart side-by-side relationship and are placed within the housing 44 in order to divide the internal space 50 to define around the exteriors of the tubular members 46 the flow path for the blow-by gas. It can be seen that plates 52(b,c) have respective cutaway sections comprising part of the blow-by gas flow path. Thus, where the tubular members are hexagonal in cross-section, the partition plates have a honeycomb arrangement as illustrated in figures 6a to 6c. To increase yet further oil recovery from the blow-by gas, a mesh material 54 (figure 7) may be located at least adjacent the blow-by gas outlet 30e of the heat exchanger 30 in order to "filter" any oil droplets being carried toward said outlet 30e by the blow-by gas. The heat exchanger may incorporate a sump pressure regulating valve 56 (figure 8) which avoids the need for installation of a pressure regulating means elsewhere on the engine 10. It will be appreciated that the features of the second (figure 7) and third (figure 8) embodiments of the heat exchanger can be incorporated together in a single heat exchanger for use in the apparatus according to the invention. Figures 9 and 10 illustrate an internal combustion engine including an apparatus 12 in accordance with a third embodiment of the invention. This differs from the apparatus 12 of the first and second embodiments of the invention insofar that the heat exchanger 30 is of a simpler construction. The heat exchanger 30 comprises a chamber located in the blow-by gas passage 32. The chamber is filled with a mesh material 58 to capture oil particles condensing from the blow-by gas passing through the chamber. The heat exchanger 30 has external fins 60 to increase cooling efficiency. The heat exchanger is cooled by atmospheric air flow over the fins 60 and the outer surface of the heat exchanger housing 44. Movement of a vehicle (not shown) in which an engine 10 incorporating the apparatus 12 is installed causes air flow over the chamber. However, the apparatus 12 is arranged such that the heat exchanger 30 is located behind the engine cooling fan 62 so that cooling of blow-by gas can be achieved even when the vehicle is stationary. As in the other embodiments, an oil return pipe 36 connects a base of the heat exchanger housing 44 with the engine sump 16 for return of condensed oil collected in the housing base to the sump 16. A pressure regulating valve 56 may be incorporated into the heat exchanger 30 as in the third embodiment of the heat exchanger (figure 8) . It will be appreciated that a heat exchanger comprising a part of the apparatus of the present invention can take many forms and can be cooled by any suitable cooling agent. For example, it is envisaged that with a marine engine the cooling agent will be sea water.

Claims: CLAIMS 1. A method of reducing oil content of blow- by gas in an internal combustion engine, comprising the steps of : conveying blow-by gas away from the engine crankcase; cooling said blow-by gas; returning oil condensed from said cooled blow-by gas to the engine; and conveying said cooled blow-by gas to atmosphere or to the engine air intake system. 2. A method as claimed in claim 1, wherein it includes the step of using a heat exchanger to cool the blow-by gas. 3. A method as claimed in claim 1 or claim 2, wherein it includes the step of using air from the engine air intake system to cool the blow-by gas. 4. A method as claimed in any preceding claim, wherein it includes the step of returning oil condensed from said cooled blow-by gas to the engine sump. 5. A method as claimed in any preceding claim, wherein it includes the step of conveying the cooled blow-by gas to the engine air intake system on an engine side of an air filtering means of said air intake system. 6. An apparatus for reducing oil content of blow-by gas in an internal combustion engine, the apparatus comprising : means for conveying blow-by gas away from the engine crankcase; means for cooling said blow-by gas; means for returning oil condensed from the cooled blow-by gas to the engine and means for conveying said cooled blow-by gas to atmosphere or to the engine air intake system. 7. An apparatus as claimed in claim 6, wherein the means for conveying blow-by gas away from the engine crankcase comprises the means for cooling said blow-by gas. 8. An apparatus as claimed in claim 6, wherein the cooling means comprises a heat exchanger cooled by any suitable cooling agent. 9. An apparatus as claimed in claim 8, wherein the heat exchanger is arranged such that it uses air from the engine air intake system as the cooling agent. 10. An apparatus as claimed in claim 8 or claim 9, wherein the heat exchanger is arranged such that the blow-by gas flows through said heat exchanger in a direction generally opposite to a direction of flow of the cooling agent. 11. An apparatus as claimed in any one of claims 8 to 10, wherein the heat exchanger is arranged such that the length of a flow path of blow-by gas through the heat exchanger is substantially greater than the length of a flow path through said heat exchanger of the cooling agent. 12. An apparatus as claimed in any one of claims 8 to 11, wherein the heat exchanger is arranged such that the cooled blow-by gas passes into the engine air intake system via the heat exchanger. 13. An apparatus as claimed in any one of claims 8 to 12, wherein the heat exchanger is arranged such that the cooled blow-by gas passes into the engine air intake system on an air intake system inlet side of said heat exchanger. 1 . An apparatus as claimed in any one of claims 8 to 13, wherein the heat exchanger is arranged on an engine side of an air filtering means of the engine air intake system. 15. An apparatus as claimed in any one of claims 8 to 14, wherein the heat exchanger comprises a housing containing at least one tubular member arranged with its longitudinal axis parallel with the longitudinal axis of the housing, said at least one tubular member defining a flow path for the cooling agent, an inlet for blow-by gas which communicates with space surrounding said at least one tubular member and partition plates which divide said space to define a flow path for the blow-by gas extending from said blow-by gas inlet to a blow-by gas outlet of the heat exchanger. 16. An apparatus as claimed in claim 15, wherein the heat exchanger includes a plurality of tubular members arranged spaced apart in side-by- side relationship within the housing. 17. An apparatus as claimed in claim 16, wherein the tubular members are circular in cross- section. 18. An apparatus as claimed in claim 16 or claim 17, wherein each tubular member includes a fin extending from its outer surface, the fin acting as an additional heat transfer means for cooling the blow-by gas. 19. An apparatus as claimed in claim 16, wherein the tubular members have a polygonal cross- section. 20. An apparatus as claimed in any one of claims 15 to 19, wherein the heat exchanger includes a meshed material located adjacent at least the blow-by gas outlet. 21. An apparatus as claimed in any one of claims 15 to 20, wherein the heat exchanger includes a blow-by gas pressure regulating means. 22. An internal combustion engine incorporating an apparatus in accordance with any one of claims 6 to 21.

Inventors: BEDKOWSKI MACIEJ, BEDKOWSKI, MACIEJ
Applicants: BEDKOWSKI MACIEJ, PERKINS LTD, BEDKOWSKI, MACIEJ, PERKINS LIMITED
Application year: 1996
Main classification: F01M13
IPC codes: F01M13