GB2260365A

GB2260365A - Oil Separation from i.c. engine crankcase gases

Info

Publication number: GB2260365A
Application number: GB9121049A
Authority: GB
Inventors: Paul Donald Crawford
Original assignee: Jaguar Cars Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 1991-10-03
Filing date: 1991-10-03
Publication date: 1993-04-14
Also published as: GB9121049D0

Abstract

In a V-engine crankcase gases pass via ports 40 in the main bearing supports 41 to a passage defined by a timing gear cover 25 and to a chamber 35 between the cylinder banks. Passages 45, 46 direct gases from the chamber 35 to chambers 47 in valve gear covers 24 which have outlets 49 connected to the engine inlet manifold (30, Fig. 1). Oil separated in the chamber 35 returns to the crankcase through outlets 43. <IMAGE>

Description

INTERNAL COMBUSTION ENGINES The present invention relates to internal combust:io engines and in particular to means for venting gases from the crankcase of the engine.

During operation of an internal combustion engine, combustion gases leak past the pistons from the combustion chambers into the crankcase. Conventionally these gases are recirculated, the gases being fed back to the intake manifold. The gases from the crankcase are however laden with oil droplets which should be removed before the gases are recirculated, otherwise pollution problems and excessive oil consumption will result.

According to one aspect of the present invention an internal combustion engine comprises a plurality of cylinders, pistons being slidably sealed in the cylinders to define a plurality of combustion chambers, the pistons separating the combustion chambers from a crankcase, an inlet manifold being connected to the combustion chambers for delivery of an induction charge thereto, a passage being provided from the crankcase to the inlet manifold for recirculation of the combustion gases which leak past the pistons, said passage including a chamber located intermediate of the crankcase and inlet manifold, said chamber having a plurality of baffles to provide a labyrinth route which will induce separation of oil droplets entrained with the leaked gases return passages being provided from the chamber for return of the separated oil to the crankcase.

With internal combustion engines of V-configuration, the chamber may conveniently be located between the two banks of cylinders. Alternatively or in addition, the leaked gases may be routed through chambers formed in the upper part of a camshaft cover.

An embodiment of the invention is now described, by way of example only, with reference to the accompanying drawings in which; Figure 1 shows a part sectional end elevation of an internal combustion engine in accordance with the present invention; and Figure 2 is a part sectional view along the line II-II of Figure 1.

Figures 1 and 2 illustrate an internal combustion engine 10 of V-configuration, having a pair of cylinder banks 11 which are joined together at their lower ends to form a crankcase 12. Each cylinder bank 11 has a plurality of cylinders 13, a piston 14 being slidably sealed in each cylinder 13 to define a combustion chamber 15.

Connecting rods 16 connect the pistons 15 to a crankshaft 17 which is rotatably mounted longitudinally of the crankcase 12.

The ends of the cylinders 13 remote from the crankcase 12 are closed by cylinder heads 20, one secured to each cylinder bank 11. The cylinder heads 20 define inlet and exhaust ports 21 and 22 for each of the cylinders 13, valve means of conventional construction being provided to control opening and closing of the ports 21 and 22.

The valve means are controlled by means of a pair of camshafts 24 rotatably mounted longitudinally of each cylinder head 20, the camshafts 24 being driven in conventional manner from the crankshaft 17 by means of chains which are located in a timing cover 25 formed at the front of the engine 10. Ignition devices 26 for each of the cylinders 13 are also provided in the cylinder head 20. Each cylinder head 20 is closed by means of a camshaft cover 27.

The inlet ports 21 of each of the cylinders 13 are connected to a common inlet manifold 30 by which an air/fuel charge may be delivered to each of the cylinders 13 of the engine 10 on the induction stroke of that cylinder 13.

A cast closing roof panel 36 is provided between the cylinder banks 11 and combines with end walls to define a chamber 35 therebetween. The panel 36 also imparts significant torsional stiffness to the cylinder bank 11/crankcase 12 structure. Ribs 37 are cast between the cylinder banks 11, further strengthening the structure, and ribs 38 cast onto the roof panel 36 are located intermediate of the ribs 37 to provide a labyrinth path through the chamber 35.

The chamber 35 is connected to the crankcase 12 by means of the timing cover 25, windows 40 being cast in the crankcase main bearing panels 41 to provide access between the crankcase 12 and timing cover 25 and windows 42 being provided through the end wall of chamber 35 to provide access between the timing cover 25 and chamber 35. Bores 43 are provided between the chamber 35 and the crankcase 12 for the return of oil to the crankcase 12.

The chamber 35 is connected, at the end remote from the timing cover 25, via a pair of cast galleries 45 and ducts 46 formed in the adjacent end of each cylinder head 20, to a chamber 47 formed in the upper part of each of the camshaft covers 27. The chambers 47 are provided with baffels 48 which extend alternately from opposite sides of the chamber 47 to define a labyrinth path therethrough. Outlets 49 are provided at the ends of chambers 47 remote from the connection to ducts 46. The outlets 49 are connected to the inlet manifold 30 by means of fixed sized metering ports, which control the rate of recirculation of gases from the crankcase 12.

In operation, when the engine is running, combustion gases will leak from the combustion chambers 15, past pistons 16 into the crankcase 12. These 'blow-by' gases will pickup oil droplets from the oil mist which is produced for lubrication purposes in the crankcase 12.

In order to vent the crankcase 12, the blow-by gases will pass through the windows 40, timing cover 25 and windows 42 into chamber 35. The volume of the chamber 35 and labyrinth path defined by ribs 37 and 38, will significantly reduce the velocity of the gases causing the oil droplets to separate out. Oil droplets will separate out on the ribs 37 and 38 and will be returned to the crankcase 12 via bores 43. The gases with a significant part of the oil removed are then passed through galleries 45 and ducts 46 into the chambers 47, where further oil will separate out. The gas is finally delivered via outlets 49 to the inlet manifold 30, for recirculation.

Claims

1. An internal combustion engine comprising a plurality of cylinders, pistons being slidably sealed in the cylinders to define a plurality of combustion chambers, the pistons separating the combustion chambers from a crankcase, an inlet manifold being connected to the combustion chambers for delivery of an induction charge thereto, a passage being provided from the crankcase to the inlet manifold for recirculation of the combustion gases which leak past the pistons, said passage including a chamber located intermediate of the crankcase and inlet manifold, said chamber having a plurality of baffles to provide a labyrinth route which will induce separation of oil droplets entrained with the leaked gases, return passages being provided from the chamber for return of the separated oil to the crankcase.

2. An internal combustion engine according to Claim 1 in which the engine is of V-configuration having a pair of cylinder banks which are joined together at their lower ends to form a crankcase, the chamber being located between the two cylinder banks.

3. An internal combustion engine according to Claim 2 in which a cast roof panel is provided between the cylinder banks and combines with end walls to define the chamber.

4. An internal combustion engine according to Claim 2 or 3 in which the crankcase is connected to the chamber via a passage defined by the timing cover.

5. An internal combustion engine according to any one of the preceding claims in which the or an additional chamber is provided in a camshaft cover of the engine.

6. An internal combustion engine according to any one of the preceding claims in which ribs or baffels extend alternately from opposite sides of the chamber to define a labyrinth path through the chamber.

7. An internal combustion engine substantially as described herein with reference to and as shown in Figures 1 and 2 of the accompanying drawings.