GB2118861A - Internal combustion engine filter system - Google Patents

Abstract

A four-stroke diesel engine E has a crankcase vapour duct 26 leading from a primary oil-separating device B to the inlet air side of an oil bath air cleaner C which supplies combustion air to the engine. The duct 26 is thus not subjected to the reduced pressure in the inlet duct 6 of the engine E. Oil mists precipitated in the air cleaner C combine with the oil in the oil bath. In Fig. 4 the crankcase vapour duct extends inside the air outlet duct to cool and condense the vapour. In Fig. 5 the crankcase vapour is directed straight on to the oil bath. <IMAGE>

Description

SPECIFICATION Internal combustion engine This invention relates to internal combustion engines.

An internal combustion engine having a conventional crankcase ventilating system is shown in Figure 6 of the drawings of this specification.

In this ventilating system, crankcase vapours from the crankcase rise into the rocker-arm chamber 50 and then flow through a connecting pipe 51 into an annular condenser 52 in the secondary chamber of a dry air cleaner C'.

In the condenser 52, the crankcase vapours are cooled with intake air to condense the oil mist in the vapours. The condensed oil mist flows back into the rocker-arm chamber 50, and the residual crankcase vapours rise upwardly and flow into the secondary chamber 56 of the air cleaner C' through small holes 55 perforated in an inner annular wall 53 of the condenser 52. These noncondensable fluids mix with the carburetor inlet air and are introduced into the combustion chambers of the internal combustion engine.

The above ventilating system produces the following problems: (1) The intake quantity of crankcase vapours is increased because of a negative pressure effect on the crankcase vapours in the condenser 52; (2) as the oil mists are not condensed and separated in the rocker-arm chamber 50, it is difficult to remove completely all of the oil mist in the condenser 52; (3) some of the oil mist in a crankcase ventilating system flows into the combustion chambers with the intake air, decreasing combustion performance and increasing white smoke in the exhaust gases causing added air pollution; (4) in the event of agglutination of the piston rings, the crankcase vapours increase rapidly, allowing a large quantity of engine lubrication oil to mix in the intake air causing abnormal combustion; and, (5) in some cases, an extreme increase in the compression ratio causes damage of the connecting rod.

In order to increase the oil separating performance of the condenser 52, the condenser 52 itself has to be enlarged and complicated, which results in the intake resistance of the air cleaner C' increasing. Alternatively it is possible to dispose the condenser in the primary chamber of the air cleaner and to prevent the negative pressure from working on the condenser.

However, with this arrangement residual oil mist included in the crankcase vapours coming out of the condenser sticks to cleaner elements such as filter papers which become blocked. As a result, the intake resistance increases and the engine output power decreases. Moreover, the cleaner elements are damaged by the negative pressure and the unfiltered intake air damages the cylinders.

The present invention provides an internal combustion engine having an oil bath air cleaner and a duct for feeding vapours from the crankcase of the engine into the air cleaner at the air inlet side of its filter element.

Preferably the engine includes a further oilseparating device adjacent an inlet port of the crankcase vapour duct and with this arrangement most of the oil mist in crankcase vapours can be separated by the further device, then residual oil mist is separated by the cleaner elements of the oil-bath air cleaner.

Embodiments of the invention will now be described by way of example with reference to Figures 1 to 5 of the drawings, in which: Figure 1 is a vertical, transverse sectional view of an internal combustion engine having an oil bath air cleaner; and Figures 2, 3, 4 and 5 are vertical-sectional views of alternative oil-bath type air cleaners.

Figure 1 shows a four-stroke diesel engine E which may be used to drive a refrigerator (not shown) of a refrigerated vehicle (not shown). The engine E has a crankcase 1, a cylinder block 2, a cylinder head 3 and a rocker-arm cover 4.

A breather device B is formed inside the top of the rocker arm cover 4. An oil-bath type air cleaner C is mounted on the side of the engine E with the intake combustion air passing through the air cleaner C and flowing into a combustion chamber 7 through an intake passage 6 extending through an intake manifold 5 and the cylinder head 3.

The vapour in the crankcase 1 is a mixture of combustion gas leaked from the combustion chamber 7 and a large amount of lubricating oil mist.

The crankcase vapours flow into a rocker-arm chamber 14 through an oil flow-back passage 9, a cam chamber 10, a passage 11 between tappets 12 and a push-rod passage 13, then flow into the breather device B together with lubricating oil mist generated in the rocker-arm chamber 14.

Some of the lubricating oil in the vapours sticks to a shield plate 1 5 and the rocker-arm cover 4.

Some more oil sticks to a filter 16 of the breather device B and a shield plate 18, disposed in the vapour outlet 17, catches some lubricating oil.

The crankcase vapours are processed first by the breather device B, then by the oii-bath type air cleaner C.

In this air cleaner C, intake combustion air supplied from an air inlet 1 9 is introduced into an oil-bath chamber 22 through an air introduction passage 21 in an air introduction tube 28. The intake combustion air then flows to a clean air outlet 24 through a cleaner element 23 and into the intake passage 6.

The intake air is cleaned by oil bathing in the oil-bath chamber 22 and further cleaned by the cleaner elements 23.

A crankcase vapour inlet 25 is formed as part of the air introduction passage 21. This vapour inlet 25 is in communication with the vapour outlet 1 7 of the breather device B through a vapour passage 26. Thus, crankcase vapours are introduced into the air passage 20 in the air cleaner C from the breather device B.

In this embodiment, the vapour inlet 25 is formed by fixing a short pipe to the air introduction tube 28 extending from a casing 27, of the air cleaner C. The vapour passage 26 is formed from steel pipe.

Crankcase vapours flowing into the air introduction passage 21 through the vapour inlet 25 are cleaned by oil bathing and by the cleaner element 23.

Some of the oil mist in crankcase vapours is absorbed in the oil of the oil-bath chamber 22. The residual oil mist in the vapours in absorbed in the cleaner element 23 as the air from passage 21 flows through them. The cleaner element 23 comprises such materials as steel wool. The oil mist in the vapours sticks to minute fibres of the cleaner element 23 and is also absorbed into oil sticking between the fibres.

As described above, the vapours passing into the breather device B from the crankcase 1 are also processed by the oil-bath type air cleaner C.

Consequently the oil mist in the crankcase vapours is removed substantially completely and lubricating oil mist does not mix with the intake combustion air flowing into the combustion chamber 7. As the lubricating oil in the oil mist is of the same kind as that of the air cleaner C, the oil separated from the crankcase vapours serves to clean the intake air.

In the embodiment shown in Figure 2 the vapour inlet 25 is formed to lie within a top portion of the air inlet 19.

In Figure 3 the vapour inlet 25 is formed so as to extend further into the air introductioSn passage 21 downstream from the air inlet 19.

In Figure 4 the downstream end portion of the vapour passage 26 is introduced into the intake passage 6 by passing it through the pipe wall, and consequently is disposed inside the casing 27 of the air cleaner C. The end of the vapour passage 26 is connected with the vapour inlet 25 formed in the air introduction passage 21. In this construction, since the crankcase vapours with high temperature are cooled by the intake air, condensation of oil mist is promoted.

In Figure 5 the vapour inlet 25 is directly connected to the oil-bath chamber 22. In this construction, the crankcase vapours are introduced directly into the oil bath and rise upwardly within the cleaner C, passing through the cleaner elements 23 before returning to passage 26.

The internal combustion engines embodying the present invention and described above have the following advantages: (1) As the oil separating performance of the air cleaner is quite high, the oil mist in the vapours can be removed completely thus lubricating oil mist from the crank chamber never flows into the combustion chamber together with the intake air.

Consequently, the combustion performance can be improved, and the exhaust gas become clean.

(2) Because the oil-bath chamber and the cleaner elements are utilised for separating the oil mist in the vapours, the need for special oil separating devices for the vapours can be avoided.

Moreover, because of the large oil separating capacity of an oilbath type air cleaner, the further oil-separating device can be simple so as to separate roughly the oil mist in the vapours.

Therefore, this invention can be applied to practical uses easily and cheaply.

(3) The lubricating oil separated from the crankcase vapours is of the same kind as that of the air cleaner. After absorption into the oil in the oil-bath and the cleaner elements, the lubricating oil serves to clean the intake air, therefore, the cleaning performance and intake resistance of the air cleaner can be maintained without damage, and the durability of the engine can be high.

Claims (5)

1. An internal combustion engine having an oil bath air cleaner and a duct for feeding vapours from the crankcase of the engine into the air cleaner at the air inlet side of its filter element.

2. An engine according to claim 1, in which an end portion of the crnnkcasevapourduct adjacent the air cleaner lies within an air outlet duct of the air cleaner.

3. An engine according to claim 1 or 2, in which an outlet port of the crankcase vapour duct is adjacent the surface of the oil in the oil bath.

4. An engine according to any of claims 1 to 3, including a further oil-separating device adjacent an inlet port of the crankcase vapour duct.

5. An internal combustion engine substantially as hereinbefore described with reference to any of Figures 1 to 5 of the drawings.