GB2223272A

GB2223272A - Charge cooled supercharged I.C. engine

Info

Publication number: GB2223272A
Application number: GB8919903A
Authority: GB
Inventors: Franz Moser; Helmut Priesner; Franz Rammer
Original assignee: Steyr Daimler Puch AG
Current assignee: Steyr Daimler Puch AG
Priority date: 1988-09-02
Filing date: 1989-09-04
Publication date: 1990-04-04
Also published as: SE8902900L; DE3929123A1; SE8902900D0; GB8919903D0; AT393539B; ATA215888A

Description

1 i 223272 INTERNAL COMBUSTION ENGINE COMPRISING A SUPERCHARGER This

invention relates to an internal combustion enginey which comprises a supercharger for the charge air and a charge air cooler. which is adapted to be supplied with charge air through a charge air line, from which a by-pass line branches, which by-passes the charge air cooler under the control of a directional valveg which is dependent on temperature.

Supercharged internal combustion engines, particularly compression ignition engines, are often provided with a charge air cooler in order to increase the output power and to reduce the emissions. The air which has been compressed and heated in the supercharger is cooled back to about 50 to 600C in the charge air cooler before that charge air is supplied to the combustion chamber. In most cases the charge air cooler consists of an air/air heat exchanger, which is arranged in the front portion of the vehicle in front of the water cooler. By such an arrangement it is possible not only to reduce the emissions and to increase the power but also to reduce the fuel consumption and to increase the life of the engine. But the cooling of the charge air involves also certain disadvantages, residing,for instance, . in a rougher running of the engine and in stronger combustion noises. When the ambient temperatures are very low, the intake air may even be undercooled and in that case the ignition conditions will drastically be deteriorated and the noise emission and also the emission of whit6 smoke may considerably increase. A strong cooling of the intake air will further result in a considerable ignition delay, which in the combustion chamber gives rise to high peak pressures, which may result in mechanical damage to the engine during prolonged operation.

In order to avoid said disadvantages, by-pass lines, which by-pass the charge air cooler, have already been provided for the charge air so that the compressed charge air can directly be supplied to the engine without being cooled. Such by-pass lines can be connected in case of need by a directional valve, which may consistp e.g., of a flap mechanism, a two-way valve or the like, so that the engine can be operated with charge air cooling and under operating conditions in certain ranges without charge air cooling. In Published German Application 36 27 686 it has been proposed to control the directional valve by means of a suitable actuator under the control of a control unit in dependence on the intake air pressurep the engine speed, the cooling water temperaturep the charge pressure and the like parameters of the engine in such a manner that the by-pass line will be fully opened only as the internal combustion engine performs a warming-Up operation until a lower temperature limit has been reached. Whereas such an arrangement will permit an adaptation of the charge air temperature to the actual operating condition of the engine throughout the operating map of the engine, it reauires highly expensive control and actuating meansp which will involve difficulties regarding installation, space requirement, reliability and the like.

As is apparent from EP-A2-0 080 984, a much simpler device for a bypassing of the charge air cooler has already been provided. That device comprises only a direction control flap and a flap-actuating piston, to which the charge pressure of the engine can be applied. Because the ambient temperature conditions and the temperature conditions of the combustion air are virtually not taken into account by that device, the flap will not adequately be controlled, particularly in the case of low ambient temperatures, so that the mechanical overload and the strong emission of white smoke can hardly be eliminated.

It is an object of the invention to eliminate said disadvantages and to provide an internal combustion engine which is of the kind described first hereinbefore and which distinguishes in that the cooling of the charge air is controlled by means which are particularly simple, robust. functionally reliable and effective.

In accordance with the invention that object is accomplished in that the directional valve is adapted to be controlled in dependence on the temperature which is detected by a temperature detector or the likey which is provided adjacent to a charge air line or the exhaust gas line of the internal combustion engine. That control of the directional valve in dependence only on temperature can be provided without any expenditure and can be performed by various structural means. A particularly reliable control will be performed. The temperature which is detected adjacent to the charge air line or the exhaust gas line will be influenced by the ambient temperature and by an engine temperature which indicates the operating condition of the engine so that an actually representative temperature is available for the control of the connection and/or disconnection of the by-pass linet i.e., for the cooling or non-cooling of the charge air.

If the temperature detector is disposed inside the directional valve or in a portion of the housing of the directional valve, the change-over device and the temperature sensor will constitute a space-saving unit for installation. In that case the temperature of the charge air, as a measure of the operating condition of the engine, and the housing temperature, as a measure of the ambient temperature, will both influence the temperature which is detected by the temperature detector and will ensure the desired temperature-dependent control of the di- rectional valve.

If the temperature detector is arranged in the exhaust manifold, it will also detect for the control of the directional valve a mixed temperature, which is influenced by the ambient temperature and by the operating condition of the engine and a special advantage that will be afforded, which resides in that a certain correction for altitude will be permitted. During an operation of an internal combustion engine at relatively high altitudes, the exhaust gas temperature will usually rise so that even when the ambient air temperature remains constant the change to charge air cooling will be effected sooner at a higher altitude and the inherent power loss suffered by the internal combustion engine in dependence on altitude will be reduced.

A particularly simple design will be obtained, if the temperature detector consists of a temperature-dependent switch for operating the directional valve in response to a temperature rise and/or drop through a temperature threshold. Complicated electronic control means will not be required and the directional valve will open or close the by- pass line in dependence on the con- trolling temperature.

If the temperature-sensing member of the temperature detector is surrounded at least in part by an air cushion, there will be a delay in the region of the critical temperature so that an unstable switching will be avoided by the resulting damping during an operation near the critical temperature.

Various structures may be used to operate the directional valvep which may even be manually operated in conjunction with a visual temperature indication, which can be turned on and off by the temperature detector. A simple automatic arrangement will be obtained if the means for operating the directional valve comprise an actuating cylinder, which is adapted to be connected to a pressure source by a solenoid valve, which is controlled by the temperature-dependent switch and said actuating cylinder in response to an application of pressure moves the directional valve against the force of a ret urn spring to a position in which the by-pass line is opened and the line to the cooler is closed. As virtually every vehicle is provided with a pressure source, which consists of a compressed-air system, the directional valve can suitably be operated and in case of a failure of the application of pressure to the actuating cylinder the return spring will move the directional valve to the position in which the line to the cooler is opened so that an overheating of the internal combustion engine will be precluded.

In a particularly desirable embodiment of the invention the temperature detector comprises an expansible member and the directional valve is operable in response to a temperature-dependent deformation of the expansible member. Because that expansible member is provided, the directional valve need not be operated by an on-off control but may be moved more or less to an intermediate position so that the charge air which is supplied to the combustion chamber will be at a mixed temperature because the charge air consists in part of cooled charge air and in part of uncooled charge air and a more exact adaptation to ambient air and engine conditions will thus be permitted. In a simple arrangement a longitudinally expansible element, e. g., an element which is adapted to grow, may be provided, which is pivoted to a lever which serves to operate the directional valve and which in dependence on the longitudinal expansion of said element causes the actuating lever to move the shiftable member of the directional valve to a larger or smaller extent. Alternativelyt the expansible member may consist of a bimetal spring, which is preferably wound in conical shape and which engages the pivoted shiftable member of the directional valve so that the bimetal spring can directly impart a pivotal movement to the shiftable member. The expansible members are disposed adjacent to the directional valve and will automatically be exposed to the desired controlling temperature.

In dependence on the design and in dependence on the temperature which is selected as the controlling temperature, the directional valve may be provided at the junction at which the by-pass line is connected upstream of the charge air cooler or at the outlet at which the by-pass,line opens into the charge air line coming from the charge air cooler. The arrangement at the outlet of the by-pass line will mainly be desirable if the temperature detector consists of an expansible element because said expansible elements disposed adjacent to the directional valve will then be able to determine also the mixed temperature of the charge air and to properly control the directional valve.

The subject matter of the invention is illustrated by way of example on the drawing, in which Figure 1 is a diagram illustrating an internal combustion engine, Figures 2, 3 and 4 are diagrammatic sectional views showing on a larger scale three illustrative embodiments of directional valves of said internal combustion engine.

In an internal combustion engine 1, an exhaust manifold 3 and an air receiver 4 are connected to the cylinder heads 2. The exhaust manifold 3 extends through a supercharger 5, which consists of an exhaust gas turbine 6 and a compressor 7. A charge air line 8 extends from the discharge side of the compressor 7 through a charge air cooler 9 to the air receiver 4. The chrArge air cooler 9 is disposed in front of the water cooler 10 of the internal combustion engine 1 and in front of the fan 11, which is driven by the engine.' The charge air cooler 9 is adapted to be by-passed by apharge air line 12, which branches from the charge air line 8 upstream of the cooler inlet.9a and joins the charge air line downstream of the cooler outlet 9b. A directional valve 13 for opening and closing the by-pass line 12 is installed at the junction at c which the by-pass line 12 branches from the charge air line 8. As is indicated in Figure 1 by dotted lines the directional valve 14 may alternatively be installed at the outlet at which the by-pass line 12 is connected to the charge air line coming from the cooler 9. That directional valve 13 or 14 is controlled in dependence on a controlling temperaturep which depends on the temperature of the ambient air and on the operating condition of the engine so that the by-pass line 12 will be opened and closed by the directional valve in dependence on temperature for connection to and disconnection from the charge air cooler. The controlling temperature is detected by a temperature detector 15, which is provided adjacent to a charge air line or an exhaust gas linet e.g., adjacent to the directional valve 13 or adjacent to the exhaust manifold 3.

As is indicated in Figure 2 the directional valve 13 comprises a direction control flap 17, which is pivoted in a housing 16 and can be operated by an actuating cylinder 18. The actuating cylinder 18 is connected by a solenoid valve 19 to a pressure source 20. In response to pressure applied to the actuating cylinder 18 the flap 17 is pivotally moved against the force of a return spting 21 to a control position in which the by-pass line 12-is open and the charge air line leading to the cooler inlet 9a is closed. The solenoid valve 19 is con- trolled by a temperature dete ctor, which consists of a temperature- dependent switch 15a and which is installed in the housing 16 and is thus influenced via the housing wall by the ambient temperature and via the charge air by a temperature which reflects the state of the engine. If the temperature- sensing member 22 of the temperature detector 15 is surrounded by an air cushion 23, which is constituted, e.g., by a sufficiently deep blind bore in the housing 16, the critical temperature of the temperature detector will change in accordance with a hysteresislike function so that a frequent switching of the solenoid valve 19 at temperatures close to the critical temperature will be avoided. When the temperature has reached the set threshold valve, the temperature- dependent switch 15a will open the solenoid valve so that the actuating cylinder 18 will be forced to the illustrated control position. When the temperature drops below the threshold valuel the temperature-dependent switch 15a will reversely switch the solenoid valve 19 so that the actuating cylinder 18 will be vented and the return spring 21 will move the direction control flap 17 to its other control position, in which the by-pass line 12 is closed and the charge air line leading to the cooler inlet 9a is open. That control position will also be assumed when the application of pressure to the actuating cylinder 18 fails for any reason whatever. As a result, an overheating of the engine will reliably be avoided.

I As is illustrated in Figure 3. the directional valve 14 installed at the outlet at which the by-pass line 12 is connected to the charge air line coming from the cooler inlet 9b may be operated by a temperature detector 15, which comprises a longitudinally expansible element 15b and acts on a lever 17a 1 z 1 1 for operating the direction control flap 17. In that case the direction control flap 17 will be pivotally moved to a position that depends on the longitudinal expansion so that the charge air flowing to the air receiver 4 will be at a mixed temperature, which depends on the actual proportion of the charge air flowing through the charge air cooler 9 and on the proportion which is supplied via the by-pass line 12. The mixed temperature is detected by the expansible element 15b, which is installed in the transitional region between the charge air line 8 and the air receiver 4. That mixed temperature will also depend on the ambient temperature and on a temperature which reflects the operating condition of the engine.

In accordance with Figure 4 the directional valve 14 may comprise a cylindrical housing 16a, which contains a pivoted segment-shaped direction control flap 17b. In that case the temperature detector 15 may consist of a preferably conically wound bimetal spring 150, which bears directly on an anchor 24, which is fixed to the housing, and on the direction control flap 17b and actuates the directional valve 16a in dependence on the actual mixed temperature.

1

Claims

1. An internal combustion engine, which comprises a supercharger for the charge air and a charge air cooler. which is adapted to be supplied with charge air through a charge air line, from which a by-pass line branches, which by-passes the charge air cooler under the control of a directional valvep which is dependent on temperature.

characterized in that the directional valve is adapted to be controlled in dependence on the temperature which is detected by a temperature detector or the like, which is provided adjacent to a charge air line or the exhaust gas line of the internal combustion engine.

2. An internal combustion engine according to claim 1p characterized in that the temperature detector is disposed inside the directional valve the directional or in a portion of the housing o.IL valve.

3. An internal combustion engine according to claim 19 characterized in that the temperature detector is mounted in the exhaust manifold.

1

4. An internal combustion engine according to any of claims 1 to 3P characterized in that the temperature detector is operatively connected to said directional valve and arranged to control said directional valve in dependence on said temperature.

11

5. An internal combustion engine according to claim 4, characterized in that the temperature detector consists of a temperature-dependent switch for operating the directional valve in response to a temperature rise and/or drop through a temperature threshold.

6. An internal combustion engine according to claim 5, characterized in that the temperature- sensing member of the temperature detector is surrounded at least in part by an air cushion.

7. An internal combustion engine according to claim 4 or 5, characterized in that the means for operating the directional valve comprise an actuating cylinder, which is adapted to be connected to a pressure source by a solenoid valve, which is controlled by the temperature-dependent switch and said actuating cylinder in response to an application of Pressure moves the directional valve against the force of a ret urn spring to a position in which the by-pass line is opened and the line to the cooler is closed.

8. An internal combustion engine according to claim 4, characterized in that the temperature detector comprises an expansible member and the directional valve is operable in response to a temperature-dependent deformation of the expansible member.

9. An internal combustion engine according to claim 89 characterized in that a longitudinally expansible element is provided, which is pivoted to an actuating lever of the directional valve.

10. An internal combustion engine according to claim 8, characterized in that the expansible element consists of a bimetal spring, which is preferably wound in conical shape and which engages the pivoted shiftable member of the directional valve.

11. An internal combustion engine according to any of claims 1 to 109 characterized in that the directional valve is provided at the outlet at which the by-pass line is connected to the charge air line coming from the charge air cooler.

12. An internal combustion engine comprising a supercharger, substantially as described hereinbe- fore with reference to and as shown on the drawing.

1 Published 1990 at The Patent Office. State House. 66 71 High Holborn. LondonWClR4TP. Further copies maybe obtained frOM The PatentOfficc Sales Branch. St Mary Cray, Orpington. Kent BR5 3RD. Printed by Multiplex techniques ltd, St Maxy Cray. Kent. Con. 187