This application claims priority to Great Britain Patent Application No. 1609910.3, filed Jun. 7, 2016. The entire contents of the above-referenced application are hereby incorporated by reference in its entirety for all purposes.
The present disclosure relates to a crankcase assembly, in particular, but not exclusively, a crankcase assembly comprising an oil catcher configured to catch dispersed oil in a crankcase and direct the oil towards a crank sump and away from a crankcase casing wall.
During warm up of an internal combustion engine, the engine block structure acts as a large heat sink because the thermal inertia of the engine block structure is an order of magnitude greater than the coolant and oil. As a result, the engine block structure takes longer to warm up than the oil.
By way of example, hot oil returning from a piston cooling gallery, which has been heated by the combustion events, may hit a crank of the engine and the oil may be thrown against the cooler crankcase. When the oil is thrown against the crankcase wall, the oil loses heat due to the large thermal inertia of the crankcase and the large surface area of the crankcase. Similarly, oil returning from the cylinder head has been heated and loses heat as it returns through the engine block to the oil sump. The resulting colder oil has a higher viscosity, which leads to higher friction losses. This in turn leads to worse fuel consumption and cabin heating.
The present disclosure seeks to address these issues.
According to an aspect of the present disclosure there is provided a crankcase assembly for an engine comprising: a crankcase comprising a crank sump; the crank sump comprising a primary sump volume and a secondary sump volume; one or more crankcase oil catchers, the crankcase oil catchers comprising one or more surfaces configured to catch dispersed oil in the crankcase and direct the oil along the surfaces of the crankcase oil catcher away from a crankcase casing wall and towards the crank sump, wherein the crankcase oil catchers are provided above a crankshaft and below an associated piston of the engine; and a guide configured to collect oil captured by one or more of the crankcase oil catchers and guide the oil to the primary sump volume, wherein the guide is provided beneath a bottom edge of the one or more crankcase oil catchers such that oil falling from the bottom edge of the crankcase oil catchers drops onto the guide at least when in the first configuration, and wherein at least a portion of the guide is movable between: a first configuration in which the guide collects oil captured by the one or more crankcase oil catchers that would otherwise have flowed into the secondary sump volume and guides the oil to the primary sump volume; and a second configuration in which the guide permits oil captured by the crankcase oil catchers above the secondary sump volume to flow into the secondary sump volume.
The configuration of the guide may be dependent on the temperature of the oil. For example, the configuration of the guide may be dependent on the temperature of the oil collecting on the guide.
The guide may be arranged in the second configuration such that at least some of the oil captured by the crankcase oil catchers above the secondary sump volume may flow onto the guide before flowing into the secondary sump volume. Alternatively, the guide may be arranged in the second configuration such that the oil captured by the crankcase oil catchers above the secondary sump volume may bypass the guide before flowing into the secondary sump volume.
The guide, e.g. all or a portion of the guide, may move between the first and second configurations.
The guide or a portion of the guide may rotate between the first and second configurations. The guide or the portion of the guide may rotate about an axis parallel or perpendicular to a longitudinal axis of the crankshaft.
The guide may comprise a movable portion that moves between the first and second configurations. The movable portion may be provided in a flow path along the guide to the primary sump portion. The movable portion may be arranged such that when in the second configuration oil flow may be diverted into the secondary sump portion.
The guide may move between the first and second configurations passively. The crankcase assembly may comprise a temperature sensitive portion that changes shape or state according to the surrounding temperature. Changes in the temperature sensitive portion may determine the configuration of the guide. The temperature sensitive portion may be operatively coupled to the guide (or movable portion) to move between the first and second configurations. By way of example, the crankcase assembly may comprise a thermostatic element comprising a wax, a liquid, a bimetallic strip or any other temperature sensitive portion.
Movement of the guide between the first and second configurations may be actively controlled. For example, the crankcase assembly may further comprise a controller, a temperature sensor operatively coupled to the controller; and an actuator, such as a solenoid, configured to move the guide between the first and second configurations.
The guides may extend in a direction parallel to a longitudinal axis of the crankshaft.
The crankcase assembly may comprise a plurality of crankcase oil catchers, e.g. one for each cylinder and piston of the engine. The guides may extend across one or more of the plurality of crankcase oil catchers, for example the guides may extend across a subset of the crankcase oil catchers and not all of the crankcase oil catchers. Alternatively, the guides may extend across the plurality of crankcase oil catchers, e.g. all of the crankcase oil catchers.
One or more first crankcase oil catchers may guide oil directly into the primary sump volume, e.g. without requiring the one or more guides. By contrast, one or more second crankcase oil catchers may be provided above the secondary sump volume and the guides may extend across the second crankcase oil catchers so as to direct oil into the primary volume.
The crankcase assembly may comprise a pair of guides with one guide on either side of the crankshaft.
The crankcase assembly may comprise a wall dividing the primary and secondary sump volumes. The guides may be integral with or separate from a wall dividing the primary and secondary sump volumes. The wall may comprise one or more openings configured to allow oil to pass between the primary and secondary sump volumes. The openings may be sized such that the flow rate of oil through openings depends on the temperature of the oil. The openings may be permanently open. The openings may be formed from a mesh or perforations.
The guides may comprise one or more openings configured to allow hot oil to pass through to the secondary sump volume beneath. The openings may be sized such that oil does not pass through openings when the oil is below a threshold temperature. The openings may be formed from a mesh or perforations.
Oil may be preferentially returned to the primary sump volume during warm-up of the engine. Restricting the initial volume of the sump may increase the rate at which the engine warms up.
The crankcase assembly may further comprise a valve provided between the primary and secondary sump volumes. The valve may be configured to selectively permit the flow of oil between the primary and secondary sump volumes, e.g. in response to a signal from a controller.
An oil pump may be provided in or above the secondary sump volume such that leakage from the oil pump may collect in the secondary sump volume. An oil pump pickup may be provided in the primary sump volume to collect oil from the primary sump volume for an oil pump.
The crankcase oil catcher may be configured to be provided above a crankshaft. The crankcase oil catcher may be configured to be provided below an associated piston. The crankcase oil catcher may be provided beneath an engine cylinder. The crankcase oil catcher may comprise a first aperture for a connecting rod to pass through. The width of the first aperture in a direction perpendicular and/or parallel to a longitudinal axis of the crankshaft may be smaller than the corresponding width of the associated engine cylinder.
The crankcase oil catcher may comprise a first lip provided around an edge defining the first aperture. The first lip may protrude form a top surface of the crankcase oil catcher. The first lip may protrude in a direction towards the piston.
The crankcase oil catcher may comprise a second aperture for a piston cooling jet to pass through or for receiving a duct for delivering a piston cooling jet. As for the first aperture, a lip may be provided around an edge defining the second aperture.
The crankcase oil catcher may be configured to be spaced apart from the crankcase casing wall. The crankcase oil catcher may be configured to substantially follow the contour of the crankcase casing wall. The crankcase oil catcher may be configured to substantially follow the contour of the crankcase casing wall in a plane perpendicular to a longitudinal axis of the crankshaft extending through the crankcase. A gap between the crankcase casing wall and the crankcase oil catcher may be between approximately 4 and 10 mm.
The crankcase oil catcher may be configured to be provided for a single cylinder of an engine. In other words, one crankcase oil catcher may be provided per piston. The crankcase oil catcher may be configured to be provided between walls between neighboring cylinders of an engine. However, it is also envisaged that the crankcase oil catcher may extend beneath a plurality of pistons.
The crankcase oil catcher may comprise a bottom surface. The bottom surface may face the crankshaft. The bottom surface may be configured to catch oil dispersed by a crankshaft, by a connecting rod and/or by a bearing between the crankshaft and the connecting rod. The crankcase oil catcher may comprise a top surface. The top surface may face the piston. The top surface may be configured to catch oil returning from above the crankcase, e.g. from a piston cooling gallery, a cylinder head or any other source of oil.
The crankcase oil catcher may comprise one or more second lips. The second lips may be provided on one or more edges of the crankcase oil catcher surfaces, e.g. on top and/or bottom surfaces of the crankcase oil catcher. The second lips may protrude above the top surface and/or below the bottom surface. The one or more second lips may be provided on edges of the crankcase oil catcher surfaces adjacent to the walls between neighboring cylinders of the engine. The one or more second lips may be provided on edges of the crankcase oil catcher surfaces substantially perpendicular to a longitudinal axis of a crankshaft extending through the crankcase.
The crankcase oil catchers and/or guides may be made from a thermally insulating material with a thermal conductivity lower than that of the crankcase. For example, the crankcase oil catchers and/or guides may be made at least in part from a plastics material, such as nylon. The crankcase oil catchers and/or guides may be connected to the crankcase casing wall via one or more thermally insulating couplings. Such couplings may be made from a plastic material, e.g. nylon.
An engine, such as an internal combustion engine, may comprise the above-mentioned crankcase assembly and/or crankcase oil catcher. Similarly, a vehicle, such as an automobile, van or any other motor vehicle, may comprise the above-mentioned engine, crankcase assembly and/or crankcase oil catcher.
For a better understanding of the present disclosure, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings. The figures are drawn to scale, although other relative dimensions may be used, if desired.
With reference to
As is depicted in
The crankcase oil catcher 100 may be spaced apart from an inner surface 18 of the crankcase 2. The inner surface 18 may be towards the top of the crankcase 2 and, in the particular example shown, the inner surface 18 may be provided on the portion 8a of cylinder block 8 that extends below cylinders 10. The crankcase oil catcher 100 may be substantially planar, e.g. plate-like, for example, with a thickness that is less than 1% of its length or width. The crankcase oil catcher 100 may lie in a plane that at least partially follows the contours of the inner surface 18 of the crankcase 2. As a result, the crankcase oil catcher 100 may be substantially parallel to the inner surface 18. The inner surface 18 and thus crankcase oil catcher 100 may trace out one or more arcs of a circle in a plane perpendicular to the crankshaft longitudinal axis 6a. The centre of the circle may substantially correspond to the longitudinal axis 6a of the crankshaft, e.g. the axis about which the crankshaft rotates. By contrast, the inner surface 18 and thus crankcase oil catcher 100 may be substantially straight in a direction parallel to the crankshaft longitudinal axis 6a. As a result the crankcase oil catcher 100 may at least partially correspond to a sector of a substantially cylindrical tube.
The crankcase oil catcher 100 may fit in a space between the crankcase inner wall 18 and an arc traced out by crankshaft 6 and a big end 7a of connecting rod 7 as the crankshaft 6 rotates. As depicted in
As shown in
Referring to
The crankcase oil catcher 100 comprises surfaces, which are configured to catch oil dispersed in the crankcase 2 and direct the oil along the surfaces of the crankcase oil catcher away from the crankcase walls 18, 22 and towards the crank sump 24. In particular, the crankcase oil catcher 100 comprises a top surface 102, which when installed faces the piston 12. Furthermore, the crankcase oil charger 100 comprises a bottom surface 104, which when installed faces the crankshaft 6.
Referring to
As shown in
As shown in
As depicted in
Referring to
The bottom surface 104 may be configured to catch oil 26c dispersed by the crankshaft 6 and/or by the connecting rod big end 7a, e.g. as they pass through the oil 26 in the sump 24. Oil collected on the bottom surface 104 may then flow along the bottom surface by virtue of gravity and the oil's surface tension. The oil may flow until it reaches the bottom edge 106 of the crankcase oil catcher 100 at which point the oil falls into the sump 24.
In either case, the top and bottom surfaces 102, 104 may prevent oil returning to the sump 24 from contacting the crankcase walls 18, 16, 20, thereby minimising the heat lost by the oil to the crankcase 2. Furthermore, oil returning from above the crankcase may be prevented from simply falling directly into the crankcase, hitting the crankshaft or connecting rod and being flung out to the casing walls.
In addition, the crankcase oil catcher 100 and the air gap between the crankcase oil catcher 100 and crankcase inner surface 18 will act as thermal insulation barrier. The motion of the crankshaft 6 and connecting rods 7 creates a rotating flow of gas with an oil mist in the crankcase. Such a flow results in additional heat loss due to forced convection from the hot gases to the colder crankcase wall. Therefore, by adding the oil catcher 100 and the air gap between it and the inner surface 18, the amount of conduction and forced heat convection from the gas motion, as well as heat loss from the hot oil, will be reduced.
The crankcase oil catcher 100 may be moulded or bent into shape during construction. Furthermore, the crankcase oil catcher 100 may be made from a low conducting thermally insulating material, for example, a plastic material, such as nylon. The selection of such a material would minimise the thermal energy transferred from the oil falling on the crankcase oil catcher 100. In addition, although not shown, the crankcase oil catcher may be connected to the crankcase casing wall 18 via one or more thermally insulating couplings and such couplings may be made from a plastic material, e.g. nylon. The couplings may comprise a fir tree type fitting, screws or any other suitable coupling. The couplings may be received in openings in the crankcase wall 18. The crankcase oil catcher may additionally or alternatively comprise flanges (not shown), which may for example fit between flanges 8′, 14′ of the cylinder block portion 8a and sump portion 14 to hold the crankcase oil catcher in place.
With reference to
Referring now to
The primary and secondary sump volumes 14a, 14b are separated by first and second dividing walls 15a, 15b. The first dividing wall 15a separates the primary sump volume 14a from the first secondary sump portion 14b′ and the second dividing wall 15b separates the primary sump volume from the second secondary sump portion 14b″. The first and second dividing walls 15a, 15b may extend in a direction substantially parallel to the crankshaft longitudinal axis 6a. The dividing walls 15a, 15b may extend to a height that is substantially equal to the standard fill level for the oil.
As depicted, one or more crankcase oil catchers 100 are arranged with their bottom edges 106 arranged above the secondary sump volume 14b. In particular, a first bottom edge 106a on one side of the crankcase oil catcher 100 may be arranged above the first secondary sump portion 14b′ and a second bottom edge 106b on the other side of the crankcase oil catcher 100 may be arranged above the second secondary sump portion 14b″.
Referring still to
The first and second guides 40a, 40b may be configured to collect and guide oil captured by the crankcase oil catchers 100 into the primary sump volume 14a. For example, the first and second guides 40a, 40b may be angled relative to a horizontal plane and extend such that collected oil flows towards the primary sump volume 14a. In particular, the guides 40a, 40b may be angled with one side of the guide higher than the side of the guide that is closest to the primary sump volume 14a.
An edge of the guides 40a, 40b may be connected to a top edge of the respective dividing walls 15a, 15b. In particular, the guides 40a, 40b may be integral with the respective dividing walls 15a, 15b.
As mentioned above, the crankcase assembly may comprise a plurality of crankcase oil catchers 100, e.g. one for each cylinder 10 and piston 12 of the engine. The guides may extend across the bottom of each of these crankcase oil catchers. Accordingly, the guides 40a, 40b may be elongate and may extend in a direction parallel to the crankshaft longitudinal axis 6a.
As depicted, the guides 40a, 40b may comprise one or more openings 42a, 42b configured to allow hot oil to pass through to the first and second secondary sump portions 14b′, 14b″ beneath. The openings 42a, 42b may be sized such that oil does not pass through openings when the oil is below a threshold temperature, e.g. by virtue of the higher viscosity at lower temperatures. The openings 42a, 42b may be formed from a mesh or perforations.
An oil pump pick up 50 may be provided in the primary sump volume 14a to collect oil from the primary sump volume for an oil pump (not shown).
The crankcase assembly may further comprise a valve 60 provided in one or both of the first and second dividing walls 15a, 15b. The valve 60 may be configured to selectively permit the flow of oil between the primary and secondary sump volumes 14a, 14b. The valve 60 may be a thermostatic valve that automatically opens at a certain temperature. Alternatively, the valve 60 may be operatively connected to a controller, which sends a signal to open the valve when a sensor (not shown) indicates to the controller that the oil has reached a threshold temperature, for example 115° C.
The valve 60 may otherwise be opened in any of the following circumstances: if the oil level at the oil pump pick up 50 is low, even if the oil is cold, to avoid oil starvation. This could be determined by an oil level sensor, oil pressure sensor or both.
During power off or engine shut down. This allows the engine to be filled with oil and drained without any issues. It also allows a levelling of oil during drain down and oil to interchange between the two volumes.
It may also be advantageous to periodically open the valve 60 (for example, once in every 20 warm-up occurrences) if the engine does not warm up fully to allow the exchange of oil between the primary and secondary volumes.
Referring still to
As depicted, a first set, e.g. pair, of crankcase oil catchers 100a, 100b may be provided above the primary sump volume 14a and may thus guide oil directly into the primary sump volume 14a. By contrast, a second set, e.g. pair, of crankcase oil catchers 100c, 100d may be provided above the secondary sump volume. A pair of guides 44a, 44b may extend beneath the bottom edges 106 of the second set of crankcase oil catchers 100c, 100d so as to collect oil falling from the bottom edges. (The oil flow is denoted by arrows B). The guides 44a, 44b are provided either side of the crankshaft and extend in a direction substantially parallel to the crankshaft longitudinal axis 6a. (NB, for the sake of clarity only one side of each crankcase oil catcher 100 is depicted in
The pair of guides 44a, 44b may be configured to direct oil into the primary sump volume 14a. In particular, the guides 44a, 44b may be angled relative to a horizontal plane (when installed) so that oil falls towards the primary sump volume 14a. The guides 44a, 44b may be angled with one end of the guide higher than the end of the guide that is closest to the primary sump volume 14a.
In contrast to the guides 40a, 40b depicted in
An end of the guides 44a, 44b may be connected to a top edge of the dividing wall 15c. As for the arrangement shown in
As for the arrangement shown in
Again, as for the arrangement shown in
An oil pump 52 may be provided in the secondary sump volume 14b. Accordingly, leakage from the oil pump may collect in the secondary sump volume. This may help promote exchange of oil between the two sump volumes. However, to avoid the pump running dry, an oil pump pick up (not shown) may be provided in the primary sump volume 14a to collect oil from the primary sump volume for an oil pump.
Referring now to
As is shown in
As is shown in
In the particular arrangement shown in
The guide 44a may be provided with an end wall 45a provided at the end of the guide opposite the primary sump portion 14a. The end wall 45a may prevent unwanted flow of the oil over the end of the guide into the secondary sump portion.
As shown in
In an alternative arrangement (not shown) the guide 44a may be connected to the dividing wall 15c, for example the guide 44a may rotate about the connection with the dividing wall 15c, e.g. with a rotational axis perpendicular to the longitudinal axis of the crankshaft. With such an arrangement oil may flow along the guide 44a in a first direction towards the primary sump portion when in the first configuration and the oil may flow in a second opposite direction when in the second configuration. In such an arrangement the end wall 45a may be omitted.
The configuration of the guides 44a, 44b may be dependent on the temperature of the oil. For example, the temperature of the oil collecting on the guide, in the primary sump volume 14a or elsewhere may determine whether the guide is in the first or second configuration. In a particular arrangement, the guide may move between first and second configurations passively. By way of example, the crankcase assembly may comprise a temperature sensitive portion that changes shape or state according to the surrounding temperature. The changing shape or state of the temperature sensitive portion may determine the configuration of the guide 44a. The temperature sensitive portion may be operatively coupled to the guide 44a to move the guide between the first and second configurations. For example, the crankcase assembly may comprise a thermostatic element comprising a wax, a liquid, a bimetallic strip or any other temperature sensitive portion that is arranged to move the guide between the first and second configurations depending on the surrounding temperature. The temperature sensitive portion may be in thermal communication with the oil falling on the guides 44a, 44b.
Alternatively, movement of the guides 44a, 44b between the first and second configurations may be actively controlled. For example, the crankcase assembly may further comprise a controller (cf.
If the configuration of the guides 44a, 44b is actively controlled, then the controller may additionally or alternatively move the guides between the first and second configurations based on factors other than temperature. For example, if the oil level in the sump volume with the oil pick up is running low, the guides may be adjusted to direct oil flow into that sump volume.
In the arrangement shown in
The arrangement shown in
Referring now to
The movable portion 47a may comprise a bimetallic strip that changes shape according to the temperature of the oil flowing over the movable portion. For example, as the temperature of the oil increases, the movable portion may flex from the first configuration to the second configuration. Although
In any of the arrangements depicted in
With the arrangements depicted in
Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
It will be appreciated by those skilled in the art that although the disclosure has been described by way of example with reference to one or more examples, it is not limited to the disclosed examples and that alternative examples could be constructed without departing from the scope of the disclosure as defined by the appended claims.
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Number | Date | Country | |
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20170350346 A1 | Dec 2017 | US |