WO2009045154A1

WO2009045154A1 - Apparatus for drainage of condensate

Info

Publication number: WO2009045154A1
Application number: PCT/SE2008/051066
Authority: WO
Inventors: Olof Erlandsson
Original assignee: Scania Cv Ab (Publ)
Priority date: 2007-10-03
Filing date: 2008-09-24
Publication date: 2009-04-09
Also published as: SE530953C2; SE0702231L

Abstract

A device for diversion of condensate (50) from a cooler (28, 48) for combustion gas to an inlet (14) for the combustion gas of a combustion engine (10), comprising a condensate line (52, 54, 56, 60) between the cooler and the inlet. The condensate line branches to separate line sections (60) each leading to close to one of a number of inlet ports of the engine (10), with a valve (62) in each line section (60) for proportioning the condensate (50) to each inlet port in response to pressure differences at the inlet ports. It is thus possible to prevent risk of the engine being subject to water hammer due to the condensate diverted to the engine.

Description

Apparatus for drainage of condensate

TECHNICAL FIELD

The invention relates to a device for diversion of condensate from a cooler according to what is indicated in more detail in the preamble of the attached claim 1. The invention also relates to a combustion engine provided with such a device.

BACKGROUND

In combustion engines for vehicles, coolers are often used for pressurised combustion air (in turbocharged engines) and for pressurised exhaust gases which are to be recirculated (EGR systems). In unfavourable operating situations, however, large amounts of condensate may accumulate in the coolers. During acceleration there is then risk of condensate being drawn into the engine and causing engine damage due to water hammer.

Various solutions are known for dealing with this problem: US 6367256 proposes an electric heater to vaporise the condensate. According to US 4055158 and US 6748741 , condensate is drained from an EGR cooler to surrounding air via downcomers which intercept condensate.

It may be advantageous, however, to cause the condensate to be led back to the inlet in order to appropriately lower the combustion temperature and hence also reduce the formation of nitrogen oxides.

According to WO 98/07975, condensate is deliberately generated in a cooler and is supplied to a separate tank, which may also be replenished with water and from which the condensate is introduced into the engine's cylinders to influence the combustion. A remaining problem in multi-cylinder engines is the difficulty of distributing the condensate evenly to the various cylinders with a view to minimising the risk of water hammer.

SUMMARY OF THE INVENTION

An object of the invention is to further develop the prior art so that the condensate can be distributed in a more controlled manner to the inlet.

According to an aspect of the invention, the condensate line branches into separate line sections which each lead to one of a number of inlet ports of the engine, with a valve in each line section for proportioning the condensate to each inlet port in response to pressure differences at the inlet ports. A small even flow of condensate can thus be extracted continuously from the cooler during operation of the engine and also be distributed evenly to the engine's cylinders to prevent any local build-up in an individual cylinder of a water mass which might cause water hammer in the engine.

The condensate may be distributed by self-regulation to the inlet ports if said valve is a check valve in the line section. The valve may then also be a venturi valve at the inlet.

Other features and advantages of the invention may be indicated by the claims and the description of embodiment examples set out below.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. l is a schematic view of a combustion engine with a device for diversion of condensate according to the invention;

Fig. 2 depicts an alternative embodiment of a device according to the invention;

Fig. 3 is a sectional view of part of an inlet pipe to a combustion engine of a device according to the invention; and

Fig. 4 depicts, corresponding to Fig. 3 but on a larger scale, part of an alternatively configured inlet pipe according to the invention. DESCRIPTION OF EMBODIMENT EXAMPLES

Fig. 1 depicts a combustion engine 10 with a plurality of cylinders 12. The engine 10 has in a conventional manner an inlet 14 for combustion air/gas and an outlet 16 for exhaust gases. An exhaust line 18 extends from the outlet 16.

Although many variants may be possible, the engine 10 in the example depicted is equipped with both a supercharger in the form of a turbocompressor 20 and an EGR system 40. The invention is also applicable to engines with only one of these or similar units.

The turbocompressor 20 comprises in a conventional manner a turbine 22 incorporated in the exhaust line 18. The turbine 22 drives a compressor 24 incorporated in an inlet line 26 to compress the air supplied to the inlet 14 of the engine 10. There is also in the inlet line 26 a cooler 28 for the compressed inlet air (charge air).

The EGR system also comprises in a conventional manner an EGR line 46 incorporated in the exhaust line 18 for leading part of the exhaust gases back to the engine inlet 14 via the inlet line 26. A venturi unit 70 may be arranged in the inlet line 26 to introduce the exhaust gases from the EGR line 46 into the inlet line 26. The proportion of exhaust gases led back may also be regulated by an EGR valve 42 in the EGR line 46. There is also in the EGR line 46 a cooler 48 for cooling the exhaust gases led back. The coolers 28, 48 not depicted in more detail may be of known types, such as coolers of the gas-liquid type or gas-gas type.

In certain conditions during operation of the engine 10, condensate 50 may accumulate in the coolers 28, 48. At the bottom or at other locations on each cooler 28, 48 where condensate may accumulate, there is therefore in each case an outlet line 52, 54 for the condensate 50, from which the condensate 50 is conveyed to the inlet 14 by the above-atmospheric pressure of the charge air and/or the exhaust gases led back in the coolers 28, 48. In the example depicted with two coolers 48, 28, the condensate is brought together from the outlet lines 52, 54 to a common inlet line 56 via a valve 58. The valve 58, which may be necessary if the exhaust pressure in the cooler 48, for example, is lower than the charge air pressure in the cooler 28, may be of venturi type or of a type which connects one of the outlet lines 52 and 54 alternately to the inlet line 56.

The inlet line 56 extends branchingly via line sections 60 to the inlet 14 of the engine 10. More specifically, each line section 60 extends into the inlet 14 to the vicinity of an inlet port, not depicted in more detail, for each cylinder 12. The line sections 60 and the lines 52, 54, 56 may have relatively small flow cross-sections to limit the amount of condensate which can be transferred through them and hence to reduce the risk of water hammer. In each line section 60 there is also a valve 62.

In the embodiment according to Fig. 1 , each valve 62 is a check valve adapted to proportioning the condensate to the respective cylinder 12 in response to the pressure variation which occurs at the respective inlet port during operation of the engine 10.

Each check valve 62 is therefore adapted to opening and to delivering an amount of condensate to the respective cylinder 12 as a result of the pressure reduction which occurs at the inlet 14 during an intake stroke of the cylinder 12 and the pressure increase which occurs at the outlet 16 during a discharge stroke of the cylinder 12.

The check valve 62 may for example be a vertically oriented ball valve with or without closing springs.

Fig. 2 depicts an example of the possibility of varying a device according to the invention. While one of the coolers 28, 48, in this example the cooler 28 for the charge air, may be adapted to diverting the condensate to the engine inlet in any of the ways described above, the condensate from the other cooler 48, in this example the cooler 48 for the recirculated exhaust gases, is diverted via the outlet line 54 to the venturi unit 70 in order to be mixed with and accompany the charge air in the line 26 to the engine inlet 14. In the embodiment according to Fig. 3, each valve 62 is a venturi valve arranged in an inlet 14 in the form of a branch pipe in the vicinity of each of the engine's inlet ports.

As illustrated in Fig. 4, each venturi valve 62 may also be adapted to replacing the venturi unit 70 in Fig. 1. hi other words, the EGR line 46 then branches to the respective venturi valve 62. As further illustrated in Fig. 4, the condensate lines 52 and 54 may also each branch to the respective venturi valve 62. Fig. 4 shows how the axial positioning of the inlet apertures of the lines 46, 52, 54 in the intake duct section of the venturi valve 62 can be adapted to optimise the suction force of the charge air flow from the respective lines 46, 52, 54.

It will be obvious to one skilled in the art that the invention can be modified without departing from the concept of the invention or the scope of the claims set out below. For example, the invention is also usable with advantage for engines which are not supercharged or which are provided with EGR systems.

Claims

1. A device for diversion of condensate (50) from a cooler (28, 48) for combustion gas to an inlet (14) for the combustion gas of a combustion engine (10), comprising a condensate line (52, 54, 56, 60) between the cooler and the inlet, characterised by branching of the condensate line to separate line sections (60) each leading to close to one of a number of inlet ports of the engine (10); and a valve (62) in each line section (60) for proportioning the condensate (50) to each inlet port in response to pressure differences at the inlet ports.

2. A device according to claim 1, characterised in that said valve is a check valve (62) in the line section (60).

3. A device according to claim 1 or 2, characterised in that said valve is a check valve (62) at the inlet (14).

4. A device according to claim 3, characterised in that venturi valve (62) is also an EGR venturi valve.

5. A combustion engine (10) comprising a device according to any one of the foregoing claims.