DE10309808A1 - Cooling system for internal combustion engine with two-stage charging has cooling group consisting of the first and second charging air radiators and coolant radiator fixed relative to engine - Google Patents

Abstract

The cooling system has a first charging air radiator (10) between first and second compressors (5,6) and a second charging air radiator (11) downstream of the second compressor. The second exhaust gas turbo charger (3) is preferably able to be bypassed on the exhaust gas side and the cooling group consisting of the first and second charging air radiators and a coolant radiator (13) is fixed relative to the engine.

Description

The invention relates to a cooling system for an internal combustion engine two-stage charging, with a charge air line, in which a first compressor one first exhaust gas turbocharger and downstream of this a second compressor one second exhaust gas turbocharger is arranged, between the first and the second compressor a first charge air cooler and downstream of the second Compressor a second charge air cooler is arranged.

From JP 62-085123 A is a cooling system of an internal combustion engine two-stage charging of the type mentioned is known. By the first Charge air cooler between the first and the second compressor can Charge air temperature are reduced so far that there is no thermal overload of the second compressor occurs. However, there is none in the known cooling system Regulation of the state of charge depending on the operating state is provided. This has the disadvantage that the exhaust gas turbocharger is not always optimal Efficiency can be operated.

From DE 39 33 518 A1 is an internal combustion engine with sequential Turbocharger system with a first-stage, large-volume turbocharger and one known two-stage, small-volume turbocharger. By means of a Intake bypass valve can bypass the two-stage, small-volume turbocharger. In the known cooling system is a charge air cooler downstream of the first Compressor, but no intercooler between the first and the second Compressor provided. Due to the high outlet temperature from the first The second compressor, in particular the compressor impeller, becomes thermal highly stressed, especially when a conventional, cast Aluminum compressor wheel is used. With conventional Aluminum compressor impellers can become so-called due to excessive operating temperature Problems of low cycle fatigue come. When turning up the Compressor impeller tensions in the hub area. When the speed is reduced it occurs as a result of stress redistribution in the hub area Compressive stresses. This swelling strain causes a certain Cycle number with critical design a destruction of the impeller. Through the Intercooling can prevent this. Similar cooling systems show the US 5,020,327 A, US 5,142,866 A and US 5,408,979 A.

Cooling systems in which one or more coolers in the jacket area of a radial Fans are arranged, are from the publications US 3,800,866 A, US 4,202,296 A, US 6,164,909 A, EP 1 045 217 A1, DE 199 50 754 A1, DE 199 50 755 A1 and DE 197 24 728 A1 are known. This enables higher ones Cooling capacities, shorter charge air lines and thus shorter response time of the Motors as well as lower weight and smaller dimensions compared to a conventional stem cooling system with an axial fan. The better one Efficiency of the radial fan reduces the fuel consumption of the Internal combustion engine. From DE 197 24 728 A1 it is known that the fan generates Volume flow of the cooling air through at least one cooler through a blind regulate.

In conventional cooling systems, the charge air or coolant coolers are mounted on the vehicle. This requires flexible elements in the Charge air lines and / or must be provided in the cooling lines, which Compensate for relative movements between the engine and the chassis. moreover are flexible elements between the fan casing and the motor required. The publications US 4,213,426 A, US 4,522,160 A and US 4,774,911 A disclose such cooling systems.

From US 5,597,047 A is a cooling system with a liquid cooler known, which is mounted on a motor-fixed frame. Between this on Motor-mounted frame and the liquid cooler are damping elements arranged. Such motor-fixed cooling devices have the advantage that the Connection lines can be short.

The object of the invention is to provide a powerful cooling system for To develop an internal combustion engine which is space-saving and light in weight, has few components and a long service life.

Furthermore, a high degree of efficiency should be guaranteed.

According to the invention, this is achieved in that the second exhaust gas turbocharger, is preferably bypassable on the exhaust gas side and that the first and second Intercooler and the existing coolant cooler group engine-fixed is executed. The two charge air coolers on the one hand and the bypassability of the second compressor on the other hand allows the use of conventional and thus inexpensive exhaust gas turbochargers. The two-stage design of the Charging can be relatively cheap even at very high charging levels Materials are used. The first charge air cooler ensures that the Charge air temperature between the two compressors drops so far that too with the second compressor, a conventional cast aluminum compressor wheel can be used without having too high an inlet temperature in the second compressor to affect the life of the compressor wheel. This also raises the problem of low-cycle fatigue on the compressor wheel prevented. Due to the bypassability of the second compressor - the High pressure compressor - by means of the bypass line and at least one or more valves with high amounts of exhaust gas - for example at high loads and engine speeds - it is possible to operate both exhaust gas turbochargers in optimal operating ranges, what a significant efficiency advantage over unregulated serial Charging systems. The rotor of the little ones High-pressure turbine-compressor combination turns up quickly even with low exhaust gas energies. This will create a very fast response behavior of the internal combustion engine achieved.

The engine-fixed arrangement of the cooler group allows small distances between the components, since relative movements do not have to be taken into account. The The cooling system can thus be kept very compact. Furthermore, the What are the use of flexible elements in the charge air lines? has a beneficial effect on costs and maintenance intensity. In particular can with flexible pipe elements such as rubber pipes low fatigue strength can be dispensed with. The suspension of the cooler group in a vehicle frame via rubber bearings is not required. The engine-fixed cooler group is installed together with the internal combustion engine and in the vehicle the transmission lifted into an elastic drive unit suspension. By the There are also no flexible elements in the charge air lines no more gas reaction forces on the individual coolers and lines. Consequently separate support elements or the like can be omitted.

In order to obtain a particularly high cooling efficiency, is in one preferred embodiment of the invention provided that the cooler group is arranged radially around the circumference of a radial fan. Compared to a conventional stem cooling system with an axial fan Charge air lines in a radial fan around the circumference of the jacket keep the arranged cooler group very compact and short. This makes it possible to keep the construction volume and the system weight very low. Be further the pumping losses in the long lines to and from the intercooler I reduced, which can significantly improve fuel consumption. Finally, it is possible to additionally increase the response time of the internal combustion engine reduce, since smaller volumes have to be filled. Through the cooler group with radial fan can also be compared to an axial fan with the same Installation space a significantly larger cooling surface of the coolant cooler, however the intercooler can be reached. In comparison to the axial fan has a Radial fans have a significantly better efficiency, which means that Fuel consumption of the internal combustion engine can be reduced.

To regulate the cooling air requirement, the fan has a switchable coupling driven. As a result, the drive power can be reduced when cooling air is required be blocked. It can preferably be provided that the clutch is external via a cooling air temperature sensor and an electronic control unit is controlled. The cooling air temperature sender is downstream of the Coolant cooler arranged and gives the control unit the necessary information about the Coolant temperature. The control unit evaluates this and gives the clutch corresponding switching signals.

In a further embodiment of the invention it is provided that at least between two coolers of the cooler group and / or at least one in the bulkhead Cooling slot for cooling an auxiliary device, for example an aggregate, one Vibration damper, an oil filter or the like is arranged. The um the radiator group arranged on the radial fan has a bulkhead on the engine side to the internal combustion engine. This will cause the fan inside the The cooler group creates an overpressure, causing the air to conform to the design through the charge air and coolant coolers as well as the targeted ones Cooling slots for the auxiliary devices can escape.

In the context of the invention it is further provided that the charge air line at least in sections as a multi-chamber component, preferably as Two-chamber component is executed. The two-chamber components Charge air lines can, provided with appropriate stiffeners and screw bosses, act as support brackets for the coolers.

Furthermore, it can be provided that the coolant line of the cooling system at least in sections as a multi-chamber component, preferably as Two-chamber component is executed.

It is particularly advantageous if at least one multi-chamber component as combined coolant and charge air line acts. To not in this case the approx. 45 ° C cooled charge air to be warmed up by the coolant at approx. 90 ° C, it is advantageous if the charge air space in the multi-chamber component compared to the Coolant compartment is insulated.

Finally, it can be provided that at least one charge air cooler is replaced by a Radiator blind is closable. This allows the heat dissipation in Coolant cooler can be increased. The air only blows when the radiator shutter is closed through the coolant cooler of the internal combustion engine.

Another advantage for the engine-mounted design of the cooler group is that Exchange the arranged between the fan and the bulkhead Fan drive belt is significantly simplified. By disassembling the inlet nozzle to the radial one Fan and the fan itself is the one located in the cooler chamber Belt drive freely accessible.

In an extremely compact embodiment of the invention it is provided that the second charge air cooler essentially in the cross-engine direction between the first Intercooler and an intake manifold is arranged. The second Charge air cooler thus partially takes over the flow connection to the Inlet collector so that connecting lines can be saved.

The invention is explained in more detail below with reference to the figures. Show it

Fig. 1 and 2, the internal combustion engine according to the invention in perspective views,

Fig. 3, the internal combustion engine in a plan view with disassembled cylinder head,

Fig. 4, the internal combustion engine in a section along the line IV-IV in Fig. 3

FIG. 4a the detail IVa in Fig. 4,

Fig. 5, the internal combustion engine in a side view;

Fig. 6 shows the cooling system in a section along the line VI-VI in Fig. 5,

Fig. 7 shows the cooling system in a section along the line VII-VII in Fig. 5 and

Fig. 8 shows the detail VIII in Fig. 7.

The internal combustion engine 1 has a two-stage supercharging with a first exhaust gas turbocharger 2 and a second exhaust gas turbocharger 3 . The first compressor 5 of the first exhaust gas turbocharger 2 is arranged in the charge air line 4 and, downstream of this, the second compressor 6 of the second exhaust gas turbocharger 3 is arranged. Reference number 7 denotes the first exhaust gas turbine of the first exhaust gas turbocharger 2 and reference number 8 the second exhaust gas turbine of the second exhaust gas turbocharger 3 . The first stage first exhaust gas turbocharger 2 is of large volume, the second stage second exhaust gas turbocharger 3 is of small volume.

The second exhaust gas turbine 8 of the second exhaust gas turbocharger 3 can be bypassed by means of a bypass device 9 having at least one valve.

A first charge air cooler 10 is arranged in the charge air line 4 between the first compressor 5 and the second compressor 6 . Another, second charge air cooler 11 is provided downstream of the second compressor 6 . The charge air coolers 10 , 11 are part of a cooler group 12 , which also includes the coolant cooler 13 , consisting of the radiators 14 , 15 and 16 . The second charge air cooler 11 is arranged transversely to the internal combustion engine 1 between the first charge air cooler 10 and the side of the intake manifold 20 or the radiator 14 of the coolant cooler 13 , essentially parallel to the cylinder head plane. In this case, connecting lines to the inlet header 20 can be partially saved or made shorter. The cooler group 12 is arranged radially around a radial fan 17 driven by the crankshaft 1 a via a switchable clutch 17 a and a belt 17 c.

The switchable clutch 17 a can be controlled externally via a cooling air temperature sensor 17 b and a control unit ECU.

On the inlet side, the cooler group 12 has a removable inlet nozzle 18 . After dismantling the inlet nozzle 18 and the fan 17 , the belt drive for the fan 17 is exposed, whereby the drive belt 17 c of the radial fan 17 can be easily replaced.

It is essential that the cooler group 12 is engine-fixed, that is to say rigidly connected to the internal combustion engine 1 . The motor-fixed arrangement allows small distances between the components, since no relative movements have to be taken into account, and thus a high packing density, as well as good efficiency at the fan inlet, since only small gaps between the fan 17 and the surrounding fan housing or the inlet nozzle 18 have to be provided. The use of flexible elements in the charge air lines 4 can be dispensed with. This reduces the manufacturing effort and has an advantageous effect on the service life, since there is no need for rubber elements that are susceptible to aging. By eliminating the flexible elements in the charge air lines 4 , there are also no more gas reaction forces on the individual coolers and lines. Separate support elements or the like can thus be dispensed with.

A bulkhead 19 is provided between the cooler group 12 and the internal combustion engine 1 , as a result of which the cooler group 12 is closed off on the engine side. Within the housing of the cooler group 12 , excess pressure is generated by the fan 17 , the air escaping according to the design by the charge air cooler 10 , 11 and the coolant cooler 13 . Specifically adapted cooling slots 19 a can be provided between the coolers 10 , 11 and 13 and / or in the bulkhead 19 in order to be able to specifically cool units, vibration dampers 31 , oil filters, etc. The cooling vanes of a vibration damper 31 designed as a viscous damper are designated by reference numeral 32 , in the area of which cooling slots 19 a are arranged.

The flow resistances of the coolers 10 , 11 , 13 are optimized via the size and depth of the cooler group 12 .

If necessary, the charge air coolers 10 , 11 can be closed via radiator shutters 30 on the inlet or outlet side of the cooling air flowing through. The radiator blind 30 can be operated by compressed air cylinder 30 a or the like. When the radiator blind 30 is closed, the cooling air only flows through the coolant cooler 13, for example in engine braking mode.

The charge air coming from an air filter, not shown, enters the first compressor 5 of the first exhaust gas turbine 2 , is compressed here and is guided to the first charge air cooler 10 in accordance with the arrow P1. The charge air is intercooled in the first charge air cooler 10 and then reaches the second compressor 6 of the second exhaust gas turbocharger 3 in accordance with the arrow P2. In the second compressor 6 , which is designed as a high-pressure stage, the charge air is compressed further and, in accordance with arrow P3, is led to the second charge air cooler 11 , where the charge air is further reduced in temperature. The charge air P4 leaving the second charge air cooler 11 is led to the intake manifold 20 and further to the individual cylinders 21 .

At least one section 4 a of the cooling system can be designed as a multi-chamber component, for example as a two-chamber component 22 . The two-chamber components can thus take on both the function of the inlet and the function of the return to and from the charge air coolers 10 , 11 . Provided with appropriate stiffeners and screw slugs, the two-chamber components 22 can also function as support brackets for the coolers. Furthermore, it is possible to use one chamber of the multi-chamber component as a coolant and another chamber of the multi-chamber component as a charge air line, as shown in FIG. 8. In this case, however, it is necessary to isolate the charge air space 33 from the coolant space 34 . The insulation is designated by reference number 35 .

Claims (14)

1. Cooling system for an internal combustion engine ( 1 ) with two-stage supercharging, with a charge air line ( 4 ) in which a first compressor ( 5 ) of a first exhaust gas turbocharger ( 2 ) and downstream of this a second compressor ( 6 ) of a second exhaust gas turbocharger ( 3 ) is arranged between the first and the second compressor ( 5 , 6 ) a first charge air cooler ( 10 ) and downstream of the second compressor ( 6 ) a second charge air cooler ( 11 ), characterized in that the second exhaust gas turbocharger ( 3 ), preferably is bypassable on the exhaust gas side and that the cooler group ( 12 ) consisting of the first and second charge air coolers ( 10 , 11 ) and a coolant cooler ( 13 ) is engine-fixed. 2. Cooling system according to claim 1, characterized in that the cooler group ( 12 ) is arranged radially around the circumference of a radial fan ( 17 ). 3. Cooling system according to claim 2, characterized in that the cooler group ( 12 ) arranged around the radial fan ( 17 ) on the motor side has a bulkhead ( 19 ) for the internal combustion engine ( 1 ). 4. Cooling system according to claim 2 or 3, characterized in that at least between two coolers ( 10 , 11 , 13 ) of the cooler group ( 12 ) and / or in the bulkhead ( 19 ) at least one cooling slot ( 19 a) for cooling an auxiliary device, for example, an assembly, a vibration damper, an oil filter or the like is arranged. 5. Cooling system according to one of claims 1 to 4, characterized in that the charge air line ( 4 , 4 a) is at least partially designed as a multi-chamber component, preferably as a two-chamber component ( 22 ). 6. Cooling system according to one of claims 1 to 5, characterized in that the coolant line of the cooling system is at least partially designed as a multi-chamber component, preferably as a two-chamber component ( 22 ). 7. Cooling system according to claim 5 or 6, characterized in that at least one multi-chamber component as a combined coolant and Charge air duct acts. 8. Cooling system according to claim 7, characterized in that the charge air space ( 33 ) in the multi-chamber component is insulated from the coolant space ( 34 ). 9. Cooling system according to one of claims 1 to 8, characterized in that at least one charge air cooler ( 10 , 11 ) can be closed by a radiator blind ( 30 ). 10. Cooling system according to one of claims 1 to 9, characterized in that the fan ( 17 ) via a switchable clutch ( 17 a) is driven. 11. Cooling system according to claim 10, characterized in that the clutch ( 17 a) can be controlled externally via a cooling temperature sensor ( 17 b) and an electronic control unit (ECU). 12. Cooling system according to one of claims 1 to 11, characterized in that the fan ( 17 ) via a belt ( 17 c) through the crankshaft ( 1 a) of the internal combustion engine ( 1 ) can be driven, the belt ( 17 c) inside the cooler group ( 12 ) is arranged between the fan ( 17 ) and the bulkhead ( 19 ). 13. Cooling system according to claim 12, characterized in that the inlet nozzle ( 18 ) of the cooler group ( 12 ) and the fan ( 17 ) from the end facing the cooling air flow can be removed. 14. Cooling system according to one of claims 1 to 13, characterized in that the second charge air cooler ( 11 ) is arranged substantially in the transverse direction of the engine between the first charge air cooler ( 10 ) and an inlet header ( 20 ).