DE3421355A1 - Method for the operation of an internal combustion engine with exhaust turbocharger and device for implementing the method - Google Patents

Abstract

In order to improve the speed characteristic and to reduce the turbine temperature of a supercharged internal combustion engine (1) it is proposed to inject a non-combustible liquid, preferably water, into the surrounding of the areas of the exhaust system (2, 3) at risk from overheating. The injection quantity is controlled by way of various engine parameters, such as, for example, the charging pressure, oil pressure or the engine speed. <IMAGE>

Description

55/84

6.6.84 hw / eh

Method for operating an internal combustion engine

with exhaust gas turbocharger and device for

Implementation of the procedure

The present invention relates to a method for operating an internal combustion engine according to the preamble of claim 1, and a device for performing the method.

In internal combustion engines with exhaust gas turbochargers designed for full load, the problem arises that with reduced Speed and / or load, the turbocharger is no longer delivering sufficient boost pressure. Therefore, at Vehicle engines, as well as the turbocharger for highly charged diesel engines, are designed for partial load operation, which means A sufficiently high boost pressure is available at reduced engine speed and / or load. If the speed and / or Load is increased, but a harmful increase in boost pressure can occur. This is the case with known trainings prevented by the arrangement of a relief valve, which is provided on the exhaust side or air side can be.

A disadvantage of these known devices is, on the one hand, the structural complexity in the form of valves and / or Flaps in the exhaust and combustion air lines. In addition, these arrangements can lead to mechanical problems lead, especially if they are provided in the exhaust pipes, since there are malfunctions due to coking, Soot effects and overheating can occur. There are also frequent noise emissions caused by the gases flowing through.

Another disadvantage is that the exhaust gas temperature rises sharply in front of the exhaust gas turbine (CiMAC report 1983, Pages 1549 to 1569).

If part of the compressed combustion air is blown off after the compressor, the pressure increases at full load The speed of the turbocharger increases significantly. This increases the volume flow through with the same pressure ratio the compressor very strongly.

It is the object of the invention to create a method for operating supercharged internal combustion engines which the turbocharger speed remains relatively low even at high engine loads and / or engine speeds. This is achieved according to the invention by the characterizing feature of claim 1.

The exhaust gas temperature and thus the turbine inlet temperature are thereby determined by the liquid injection held in relatively low ranges.

It is particularly advantageous if the liquid is primarily water, but also mixtures of water with detergents or anti-corrosion agents on those at risk of overheating Places the exhaust manifold pipe is injected. In addition, by adding

Liquid droplets to the exhaust gas at the same time a cleaning of the turbine can be achieved. With regard to the specific fuel consumption b, the air requirement of the engine 1, the excess air "K , the valve seat temperature Τ., _Σ , and the other pressure conditions in the engine, the liquid injection into the exhaust line results in the same conditions as an air blow-off valve after the compressor.

An exemplary embodiment is shown in simplified form in the drawing the inventive device for implementation of the method, with 1 denoting a part of an internal combustion engine, its exhaust pipe open into an exhaust manifold 3. This is connected to a turbine 4 of a turbocharger 5. The turbine is rotatably coupled to a compressor 6, which is about an air intake pipe 7 sucks in combustion air and through a charge air cooler 8 feeds an air distributor 9 of the internal combustion engine 1 and thus its cylinders 10. The solid arrow means the exhaust gas outlet from the turbine 4, while the contoured arrow represents the intake combustion air.

In the exhaust manifold 3 injection nozzles 11 are arranged, which via pressure lines 12 with a known per se Injection pump 13 are connected. A liquid reservoir 14 becomes liquid, preferably water or a mixture of water with detergents or anti-corrosion agents is sucked in by the injection pump 13 and fed through the pressure lines 12 to the injection nozzles 11. The injection nozzles are preferably like this arranged on the exhaust manifold 3 that the liquid is particularly at risk of overheating, for example the exhaust pipe 2 leading out of the cylinders 10 cools.

Since the turbocharger is designed for partial load, the injection of cooling liquid is started at the aforementioned points , for example at around 60% engine power. With increased engine output, ie from partial load to full load, the amount of coolant injected is increased accordingly so that the boost pressure remains constant within the permissible limits.

By mixing the hot exhaust gases with the injected ones Liquid is cooled at the same time the turbine 4 and largely protected from soot deposits.

The injection quantity can be regulated in various ways Engine parameters, for example speed, boost pressure or oil pressure.

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Claims (2)

PATENT CLAIMS Γί ./'Method for operating an internal combustion engine (1) with an exhaust gas turbocharger (5), the turbocharger (5) having a design tailored to partial engine speed and / or partial load, characterized in that when the speed is increased and / or increased the load, non-flammable liquid is injected into the vicinity of points of the exhaust system (2, 3) at risk of overheating, and that the injected amount of liquid is regulated via the boost pressure, the oil pressure and / or the engine speed. 2. Device for performing the method according to claim 1, characterized in that in the exhaust manifold (3) of the exhaust system (2, 3) at least two injection nozzles (11) are arranged over Pressure lines (12) are connected to an injection pump (13) and a liquid container (14).