GB2507976A

GB2507976A - Crankcase engine oil shield

Info

Publication number: GB2507976A
Application number: GB1220522.5A
Authority: GB
Inventors: Vivian Page; Benjamin Thomas Johnson
Original assignee: Perkins Engines Co Ltd
Current assignee: Perkins Engines Co Ltd
Priority date: 2012-11-14
Filing date: 2012-11-14
Publication date: 2014-05-21
Anticipated expiration: 2032-11-14
Also published as: GB201220522D0; GB2507976B

Abstract

Disclosed is an engine crankcase 106 and oil shield components 144 therefore. During operation of an engine 100 oil ligaments can detach from a rotating crankshaft 112 and eventually break up in to oil droplets. The oil droplets become entrained in the crankcase gases and are eventually expelled to atmosphere, thus influencing the engine's emissions level. The present disclosure provides an internal combustion engine having a crankcase 106 comprising a shield portion 144 arranged to be struck by oil ligaments which might detach from a crankshaft portion as the crankshaft rotates during use. The shield portion may be in the form of concave ribs which are axially aligned with the counterweights 122 of the crankshaft. The shield may be used to guide the oil to the oil sump 142.

Description

DESCRI PTION

CRANKCASE ENGINE OIL SHIELD

Technical Field

10001] The present disclosure relates to a crankcase and in particular to a crankcasc oil shield.

Background

10002] Open or closed circuit breather systems, used in an internal cornbustion engine, are configured to vent blow-by gases from the crankcase. The blow-by gases may also carry a substantial amount of engine oil droplets which are present in the crankcase due to the reciprocating and rotating components present in the crankcase. This process is called oil carry-over, and in case of the closed circuit breather system the blow-by gases are required to pass through a filter to minimize the amount of the oil carry-over in the blow-by gases. In the case of the open circuit breather system, where the blow-by gases are filtered and vented directly to atrnosphere, the oil carry-over can raise ernissions levels.

100031 The present disclosure is directed to solving one or more of the problems set forth above.

S umniary 100041 According to a first aspect of the present disclosure, there is provided an internal combustion engine comprising: a crankcase; a crankshaft housed within the crankcase and adapted to rotate about an axis of rotation; and at least one shield arranged within the crankcase and having a shielding surface adapted to be struck by oil ligaments which might detach from a crankshaft portion as the crankshaft rotates during usc.

10005] According to a further aspect of the invention, there is provided a shield to minimize engine oil carry-over in an internal combustion engine having a crankcase housing a crankshaft, the shield comprising: a mounting portion by which the shield connects to an interior wall of the crankcase; a shielding portion having a shielding surface arranged to be struck by a oil ligaments that detach from a crankshaft portion of the rotating crankshaft.

100061 Other features and aspects of this disclosure will be apparent from the following description and the accompanying figures.

Brief Description of the Figures

10007] Figure 1 is an internal combustion engine, according the present

disclosure;

10008] Figure 2 is a side view of a crankcase illustrating an angular position of a shield with respect to a crankshaft; and 10009] Figure 3 is an exemplary crankcase of a multi-cylinder engine, according

to another embodiment of the present disclosure.

Detailed Description

10010] The present disclosure will now be described in detail with reference being made to accompanying figures. Figure 1 shows an internal combustion engine 100, according to an exemplary embodiment of present disclosure. The engine 100 may be any type of engine (internal combustion, gas, diesel, gaseous friel, natural gas, or propane based engine etc.), may be of any size, with any number of cylinders, and in any configuration ("V," in-line, radial, etc.). The engine 100 may be used to power any machine or other device, including on-highway trucks or vehicles, off-highway trucks or machines, earth moving equipment, generators, aerospace applications, locomotive applications, marine applications, pumps, stationary equipment, and other engine powered applications.

10011] For clarity, the following description refers to a single cylinder engine only, but the principle of the present disclosure can as easily be applied to a multi-cylinder engine. The engine 100 includes a cylinder head 102, a cylinder block 104, and a crankcase 106. In the exemplary embodiment shown in Figure 1, the engine 100 may include a piston 108 configured to reciprocate within a cylinder 110 defined in the cylinder block 104 between a top dead point and a bottom dead point. The piston 108 is connected to a crankshaft 112, housed within the crankcase 106 via a connecting rod 114. Specifically, a big end of the connecting rod 114 is connected to a crank pin 116 of the crankshaft 112 and configured to rotate the crankshaft 112 about an axis of rotation 118 due to the reciprocating motion of the piston 108. The axis of rotation 118 of the crankshaft 112 runs through a center point of a main journal 120 of the crankshaft 112.

Further, a counterweight 122 is provided to balance the crankshaft 112 during rotation.

100121 As illustrated, in an exemplary embodiment, the engine 100 also includes a camshaft chamber 124, a vcnt chamber 126 and a passage 128 connecting the camshaft chamber 124 and the vent chamber 126. The camshaft chamber 124 houses a camshaft 130 having a lobe 132 to push against a push rod 134 and configured to transfer the rotary motion of the camshaft 130 into a linear motion of a tappet valve 136, housed within the cylinder head 102, via a rocker arm 138.

It will be apparent to a person having ordinary skill in the art that the engine 100 is exemplary in nature and is not intended to limit the scope of the present disclosure in any way. During operation of the engine 100, engine oil 140 present in an oil sump 142, attached with the crankcase 106, provides lubrication between the moving piston 108 and the cylinder 110 to prevent overheating. The engine oil 140 may also clean, prevent corrosion, and provide cooling by carrying heat away from moving parts, such as the crankshaft 112 of the engine 100.

Moreover, a gasket member (not shown) may be positioned between the cylinder head 102 and the cylinder block 104.

100131 During operation of the engine 100, as the crankshaft 112 rotates, the engine oil 140 carried by the counterweight 122 for lubrication may detach from the crankshaft 112 in a form of oil ligaments. As the oil ligaments travel farther from the crankshaft 122, they may have a tendency to break down into oil droplets. According to an embodiment of the present disclosure, the engine 100 includes at least one shield 144 arranged within the crankcase 106 to minimize engine oil carry-over in the engine 100. The shield 144 may be secured with the crankcase 106 using any suitable means such as welding, bolts etc. The shield 144 may be made of metal alloy, plastic, composites or any other suitable material. Alternatively, the shield 144 may be integrally made with the crankcase 106. The shield 144 may have a substantially triangular shape and may include an inner surface 146 disposed partially around an envelope defined by the rotating crankshaft 112 and radially separated from an outer circumferential edge 148 of the counterweight 122 by a pre-determined distance D. In an embodiment, the pre-determined distance D is a measure of a difference between an inner diameter of the inner surface 146 of the shield 144 and an outer diameter of the counterweight 122 from the axis of rotation 118. In an embodiment, the pre-determined distancc D may lie in range from about 8mm to 20mm. Further, the shield 144 may have a thickness T in an axial direction along the axis of rotation 118 of the crankshaft 112 which is substantially equal to a thickness of the counterweight 122. It will be apparent to a person having ordinary skill in the art that the pre-determined distance D and the thickness T may vary based on the size and running speed of the engine.

100141 The inner surface 146 of the shield 144 may have a substantially concave profile and adapted to collect the oil ligaments and aid in a downward flow into the oil sump 142. During operation, as the counterweight 122 passes the shield 144 the oil ligaments may strike the inner surface 146 of the shield 144 and form an oil film and eventually drain down into the oil sump 142. In various other embodiments of the present disclosure, the inner surface 146 of the shield 144 may have any suitable profile, such as, but not limited to, having one or more grooves, or a substantially flat surface to collect the oil ligaments and aid in the downward flow into the oil sump 142.

100151 Figure 2 is a side view of the crankcase 106 illustrating an angular positioning of the shield 144 with respect to the crankshaft 112, in accordance with an embodiment of the present disclosure. As illustrated, the inner surface 146 of shield 144 may have an angular range A from about 40 to 120 degrees to cover the envelope defined by the rotating crankshaft 112. However in various other embodiments, the angular range A may vary based on the size and running speed of the engine. Moreover, two shields 144 may be provided in a substantially diametrically opposite manner to collect the oil ligaments.

100161 Figure 3 illustrates an exemplary crankcase 300 for a multi-cylinder engine having a crankshaft 302, according to another aspect of the present disclosure. As illustrated, respective shields 144 maybe provided for plurality of the counterweights 304 of the crankshaft 302.

Industrial Applicability

10017] The industrial applicability of the shield 144 described herein will be readily appreciated from the foregoing discussion. Referring to Figure 1, the engine 1 00 may suffer from a process called blow-by where combustion gases (referred as blow-by gases) leak past the piston rings into the crankcase 106 from the cylinder 110. To prevent any damage to the piston rings the blow-by gases are required to be vented, which can be done by an open circuit breather system (OCB). Referring to Figure 1, the blow-by gases may travel through the passage 128, connecting the camshaft chamber 124 and the vent chamber 126. The blow-by gases may also carry the engine oil droplets created from the oil ligaments detached from the rotating crankshaft 112 and consequently pass through the breather system and contribute towards emissions, in another possible configuration of the engine 100, for example an overhead camshaft arrangement may include a crankcase ventilation system having an oil drain or passage for the blow-by gases to escape in a controlled manner also causes the oil carry-over.

100181 According to an aspect of the present disclosure, the shield 144 partially disposed around the envelope defined by the rotating crankshaft 112, spaced at an optimal distance based on the engine speed and size, the pre-determined distance D, and adapted to allow the oil ligaments detached from the crankshaft to impact on the inner surface 146. When the oil ligaments strike the inner surface 146 of the shield 144 they form the oil film which eventually drains back into the oil sump 142. Further, the positioning of the shield 144 may also decrease the tendency of the oil ligaments to break into the oil droplets in the crankcase 106.

Moreover, as the thiclmess T of the shield 144 in an axial direction is of a similar dimension to the thickness of the counterweights 122, 302 the oil ligaments are effectively captured by the shield 144.

100191 The shield 144 may provide an effective measure to reduce the amount of the engine oil droplets in the blow-by gases and hence improved the overall service life of the breather system. Further, as the shield 144 is partially disposed around the envelope defined by the rotating crankshaft 112 in the crankcase 106, the benefits of the present disclosure can be obtained without increasing space claim of the crankcase 106. Furthermore, the shield 144 can be easily manufactured using a metal alloy or sheet metal and can be readily fitted to the exiting engines without substantial modification to the engine design in a cost effective way.

100201 The present disclosure is particularly useful in engine applications that are likely to gcncratc high levels of oil droplets carried by the blow-by gases.

Although the embodiments of this disclosure as described herein may be incorporated without departing from the scope of the following claims, it will be apparent to those skilled in the art that various modifications and variations can be made. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure. 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

Claims What is claimed is: 1. An internal comb ustion engine compnsing: a crankcase; a crankshaft housed within the crankcase and adapted to rotate about an axis of rotation; and at least one shield arranged within the crankcase and having a shielding surfacc adaptcd to be struck by oil ligaments which might dctach from a crankshaft portion as the crankshaft rotates during usc.
2. The internal combustion engine of claim 1, wherein the crankshaft portion comprises a counterweight which defines a notional circumferential envelop as the crankshaft rotates, the at least one shield being arranged within the crankcase such that the shielding surface is spaced a predetermined distance from the envelop.
3. The internal combustion engine of claim 2, wherein the pre-determincd distance lies in a range between 8mm and 20 mm.
4. The internal combustion engine of claim 2 or claim 3, wherein the shielding portion has a width corresponding substantially to the width of the counterweight, those widths extending axially relative to the crankshaft.
5. The internal combustion engine of claim 1, wherein the shielding surface of the shield is eoneaved and adapted to collect the oil ligaments to form an oil film and drain down into the crankcase.
6. The internal combustion cnginc of claim 1, wherein the shielding surface is sized to extend partway around the envelop.
7. The internal combustion engine of claim 6, wherein the shielding surface extends an angular distance in the range of 40 to 120 degrees around the envelop.
8. A shield to minimize engine oil carry-over in an internal combustion engine having a crankcase housing a crankshaft, the shield comprising: a mounting portion by which the shield connects to an interior wall of the crankcase; a shielding portion having a shielding surface arranged to be struck by oil ligaments that detach from a crankshaft portion of the rotating crankshaft.
9. The shield of claim 8, wherein the shielding surface is coneaved.
10. The shield of claim 9, wherein the shielding surface has a radius of curvature greater than the radius of a notional circumferential envelop defined by the crankshaft portion of the rotating crankshaft.
11. The shield of claim 10, wherein the shielding surface is spaced a distance lying in the range of about 8mm to 20 mm from the envelop
12. The shield of any of claims 8 to 11, wherein the shielding surface has a width corresponding substantially to the width of the crankshaft portion.
13. The shield of any preceding claim, wherein the shielding surface has a length lying in the angular range of between 40 and 120 degrees of the notional circumferential envelop.