GB2262134A

GB2262134A - I.c. engine crankcase gas treatment system

Info

Publication number: GB2262134A
Application number: GB9225572A
Authority: GB
Inventors: Peter George Greenwood
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-12-06
Filing date: 1992-12-07
Publication date: 1993-06-09
Also published as: GB9225572D0

Abstract

A conduit 25 containing an oil separator 26 permits crank case gases to flow to the engine charge intake conduit. A filter 32 is provided to remove oil from the flow in conduit 25 and the filter may include an active carbon filter. Additional air may be admitted through adjustable inlet 35 and conduit 31 from the air filter 20. Conduit 22 from the rocker box to the filter 20 may include an oil coalescing and an active carbon filter 30. The filter may include a by-pass valve (60, 52, Figs. 5 and 6). <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO INTERNAL COMBUSTION ENGINES This invention relates to internal combustion engines.

From one aspect the invention provides an internal combustion engine comprising a crank case, an air inlet, means for mixing gases from the crank case with inlet air and supplying the mixture to a combustion chamber, and means, additional to an oil separator if present, for removing oil from the gases before mixing with inlet air.

From another aspect the invention provides an internal combustion engine comprising a crank case, an air inlet, means for mixing gases from the crank case with inlet air and supplying mixture to a combustion chamber, and means for removing oil from the gases before mixing with inlet air. The oil removing means is adapted to remove oil which may have passed through any oil separator present. Thus the removal means may comprise a filter for removing atomised oil.

There may be a coalescing filter.

There may be means for removing hydrocarbons from the gases, for example a filter.

The engine may include a gas flow conduit from the interior of the rocker box to an air flow passage, and means in the conduit for removing oil from the gas flow.

The removal means may comprise a coalescing filter. The conduit may include means for removing hydrocarbons from the gases.

There may be a gas flow conduit from the interior of the rocker box to an air flow passage, and means in the conduit for removing hydrocarbons from the gas flow.

There may be adjustable means for supplying additional air to the gases.

The invention also provides an internal combustion engine comprising a crank case, an air inlet, means for mixing gases from the crank case with inlet air and supplying the mixture to a combustion chamber, and adjustable means for supplying additional air to the gases.

The invention may be performed in various ways and one specific embodiment with possible modifications will now be described by way of example with reference to the accompanying schematic drawings, in which: Fig. 1 illustrates part of a known internal combustion engine; Fig. 2 illustrates an internal combustion engine according to the invention; Fig. 3 shows one arrangement; and Fig. 4, 5 and 6 shows modifications.

In a known internal combustion engine 10 Fig. 1 there is an oil sump 11, a crank case 12 containing a crank shown diagrammatically at 13 and connected to a plurality of pistons 14 (only one shown) respectively reciprocable in cylinders 15 in a housing 16 including cylinder head and rocker box housing 16a and cylinder block 16B. The operation of the engine 10 whether compression ignition or spark ignition, is well known and need not be described in detail. A positive crank case ventilation system is used in an attempt to prevent crank case gases, which include oil particles, and particles of unburnt fuel from entering the atmosphere.

This is achieved by combusting the gases and particles with fresh charge i.e. the fresh mixture of fuel and air.

Thus in Figure 1, an air filter 20 has an inlet 21 for air, a hose 22 connects the interior of the rocker box to the filter 20 so that gases and particles from the rocker box are mixed in the filter 20 and delivery conduit 23 with the fresh air and the mixture is delivered with fuel supplied through inlet 24 including carburettor 24a to the upper end of the cylinder 15 for combustion.

A further hose 25 connects the crank case interior to the conduit 23 for flow of gases and particles. The hose 25 includes an oil separator 26 for removal of some oil from the flow of gases and particles.

At low throttle a reduced pressure is produced in conduit 25 by air flow in conduit 23, and this reduced pressure assists in withdrawing gases and particles from the crank case. At higher throttle the pressure in the crank case and rocker box is increased and the gases and particles tend to flow out through hose 22, and a pressure-responsive means may close hose 25.

However with this method the fresh mixture of air and fuel is contaminated by the gases and particles and this leads to a reduction in the combustion of fuel in the cylinder and thus increased pollution of the atmosphere through discharge through the exhaust pipe of the engine.

In the present arrangement contamination of the fresh mixture of air and fuel by crank case gases and particles is reduced.

Thus, referring to the embodiment of Fig.2, an activated carbon filter 30 is included in hose 22; this filter 30 removed hydrocarbons from the gas flow.

An oil drain tube 30a is provided to return oil to the rocker box.

The filter 30 may for example be of nylon, felt, paper gauze or paper, impregnated with activated carbon e.g. charcoal or carbon granules.

An additional passage 31 from the air filter 20 connects with a combined filter 32 better seen in Fig. 3. Filter 32 includes an inlet 33 connected to hose 25; a coalescing filter 34 which removes atomised oil and water particles and may for example comprise nylon foam, or felt, or paper gauze, or sponge, or fibre glass. The removed particles may collect at the bottom of filter housing 32a.

The flow of air from conduit 31 into the filter 32 is controlled by an adjustable bleed control screw 35 including seal 35a. This adjustable air supply can be used to compensate for reduction in gas flow caused by filter 32.

The filter 32 includes an activated carbon filter 36 and has outlet 37 leading to conduit 23.

Filter 30 may also include a coalescing filter for removal of atomised oil. Filter 30 may be omitted.

A by pass pipe 38 connects the inlet and outlet and includes a valve 39 biased by spring 40 to a closed position. This valve 39 is opened by gas pressure if the filter 32 becomes blocked or if the engine is operating under heavy load.

Treatment of the crank case gases by filters 30, 32 enables the combustion mixture to burn more efficiently so reducing pollution emissions.

Crank case gases can become rich in hydrocarbons and this causes the engine to run rich. By bleeding in more air from conduit 31 to the crank case gases in conduit 25 and re-setting the flow of fuel at the carburettor, lower emission of unwanted material can be obtained.

Because the crank case gases and particles may be substantially removed from the mixture passing through the cylinder inlet, more efficient combustion is obtained thus a cleaner exhaust emission; lower residues in the exhaust material which may contaminate an exhaust catalyst if present, and less carbon deposits on the combustion chambers and exhaust.

Filter 32 includes a drain outlet 39 which may be plugged (see plug 50 Fig.6), or lead to a sediment bowl 49 or be connected to a pipe providing a return to the sump 11.

In the modification of Fig. 4, the filter 32 and the filter 30 are omitted and the screw 35 is used to adjust the air flow between conduit 31 and hose 25.

In the modification of Fig. 5 the active carbon filter 36 is omitted. The coalescing filter 34 removes any oil particles which have passed through the oil separator 26 if present and the air bleed screw 35 is used to adjust the fuel/air mixture entering the combustion chamber to a desired level. A bypass valve is opened by gas pressure if the filter 34 becomes blocked.

In the modification of Fig. 6, the active carbon filter 35 is omitted from filter 32. A valve 51 closing an outlet 52 from filter 34 is opened by gas pressure if the filter 34 becomes blocked.

The filter housing 32a may be provided with external fins for cooling.

The arrangements may be used in either compression ignition or sparkignition engines.

The engine may be incorporated in a vehicle for example a motor vehicle.

Claims

1. An internal combustion engine comprising a crank case, an air inlet, means for mixing gases from the crank case with inlet air and supplying the mixture to a combustion chamber, and means, additional to an oil separator if present, for removing oil from the gases before mixing with inlet air.

2. An internal combustion engine comprising a crank case, an air inlet, means for mixing gases from the crank case with inlet air and supplying the mixture to a combustion chamber, and means for removing oil from the gases before mixing with inlet air.

3. An engine as claimed in Claim 1 or Claim 2, in which the removing means comprises a filter.

4. An engine as claimed in Claim 3, in which the filter comprises a coalescing filter for particles.

5. An engine as claimed in Claim 2, in which the filter comprises a filter for removing hydrocarbons and a filter for removing oil.

6. An engine as claimed in any of claims 1 to 4, including means for removing hydrocarbons from the gases.

7. An engine as claimed in any of claims 1 to 6, including a gas flow conduit from the interior of the rocker box to an air flow passage, and means in the conduit for removing oil from the gas flow.

8. An engine as claimed in Claim 7, in which the oil removal means comprises a coalescing filter.

9. An engine as claimed in Claim 7 or Claim 8, in which the conduit includes means for removing hydrocarbons from the gases.

10. An engine as claimed in any of Claims 1 to 6, including a gas flow conduit from the interior of the rocker box to an air flow passage, and means in the conduit for removing hydrocarbons from the gas flow.

11. An engine as claimed in any of claims 1 to 10, including adjustable means for supplying additional air to the gases.

12. An internal combustion engine substantially as herein before described with reference to and as shown in Fig. 2, or Fig.3, or Fig 4, or Fig. 5, of the accompanying drawings.

13. An internal combustion engine comprising a crank case, an air inlet, means for mixing gases from the crank case with inlet air and supplying the mixture to a combustion chamber, and adjustable means for supplying additional air to the gases.

14. A vehicle including an engine as claimed in any preceding claim.