A METHOD IN OPERATING AN INTERNAL COMBUSTION ENGINE WITH AN AIR COMPRESSOR DRIVEN THEREBY

Abstract: A method in operating an internal combustion engine (13) with an air compressor (10) driven thereby, which absorbs the total output of the engine. A first and a second part (15 and 16, respectively) of the pressurized air from the compressor are supplied to the internal combustion engine as intake air and cooling air, respectively, while a third part (20) is shunted past the internal combustion engine to be supplied, together with the exhaust gases (17) from the engine and the cooling air (18), to a processing machine (21) to expand therein while performing work.

Description: A- METHOD IN OPERATING AN INTERNAL COMBUSTION ENGINE WITH AN AIR COMPRESSOR DRIVEN THEREBY The invention relates to a method in operating an internal combustion engine with an air compressor driven thereby, whic \absorbs the total output of the engine. The object of the invention is to achieve a very high total efficiency of the system ' in utilizing the pressurized air from the compressor to produce work by a complete heat regeneration between the pressurized air and the int ' ernal-÷combustion engine, implying that all the amounts of heat due to energy losses in the engine compressor system are preserved, through the possibility of adjusting the flow of cooling air and the flow of combustion air of the internal combustion engine to the characteristics of the engine. For this purpose the method according to the. invention has been given the characteristics appearing from claim 1. In order to explain the invention in more detail reference is made to the block diagram of the accompany¬ ing drawing, which illustrates the method according to the invention. A compressor 10 which aspirates atmospheric air at 11 and supplies pressurized air at 12, is connected to an internal combustion engine 13 so as to absorb the total output thereof. The compressor may be of any type, and also as far as the internal combustion engine is concerned it may be of any type, an Otto cycle engine or a Diesel engine of the 2-strokε or 4-stroke construc¬ tion, air-cooled or water-cooled. Via a control device 14 the pressurized air from the compressor is supplied on the one hand as combustion air to the internal com¬ bustion engine at 15 and on the other hand as cooling air to the internal combustion engine at 15. The cool- ing air may either cool the internal combustion engine directly (air cooling) or absorb heat from the internal combustion engine via a liquid cooling system (liquid cool ng) . The internal combustion engine gives off, on the one hand hot exhaust gases from the combustion at 17 and on the other hand heated cooling air at 18, and these gas flows-are received by a plenum 19 together with part of the pressurized air, supplied directly from the compressor at 20, to be conveyed from the plenum to a worktng machine (expander) 21, in which- the gases are caused to expand and then to escape to the atmosphere at 21. Thus, work from the fuel which is supplied to the internal combustion engine, is recovered in the working m-achine. The amount of cooling air to the engine must be adjusted by means of the control device 14 to obtain a desired engine temperature and the necessary amount of cooling air always constitutes only a small pro- portion of. the total amount of pressurized air supplied from the compressor. Also the amount of combustion air to the internal combustion engine must be adjusted by means of the control device 14, namely in such a manner that a moderate pressure drop over the engine is achieved. If the total amount of pressurized air from the compressor minus the amount of. cooling air were to be supplied to the internal combustion engine as com¬ bustion air, such a great pressure drop would be obtained over the internal combustion engine that the pressure in the plenum 19 would be considerably lower than the pressure at the pressure side of the compressor, which would lead to a low efficiency in the thermal process through which the air goes via compression, heating and expansion, and would mean that little power could be recovered from the engine compressor system. In addition, in an internal combustion engine of the 2-stroke type, the air factor of the engine is influenced by the amount of scavenging air, so that in case of this type of engine there is a further reason for adjusting the amount of air supplied to the engine. Taking into consideration the fact that the supply of cooling air and combustion air to the internal com¬ bustion engine -must be controlled so as to achieve the most favourable operating conditions for the internal combustion engine as explained above, and hence a satisfactory efficiency and a satisfactory power o the engine compressor unit, some of the compressed air from the compressor is shunted, according to the invention, by means of the control device directly to the plenum 19, as indicated at 20. Thus, the plenum receives three component amounts of air, all of which originate from the compressor, namely a first component amount of air 15 in the form of combustion air which is given off by the internal combustion engine as exhaust gases at 17 and is supplied to the plenum (the exhaust gases representing an equally great amount of gas as the com¬ bustion air supplied to the internal combustion engine), a second component amount of air 16 in the form of cool¬ ing air of the internal combustion engine, which is given off, heated, from the internal combustion engine at 18 and is supplied to the collecting chamber, and a third component amount of air 20 which is supplied directly from the compressor to the plenum. Thus, by said three gas flows exhaust heat, cooling heat and compression heat is supplied to the plenum. In the plenum a homogeneous mixing of the three gas flows supplied is obtained and this, mixture is the end- -product of the engine compressor unit, i.e. a hot high-pressure gas which can perform work in the working machine, (the expander). The heat regeneration described is complete since all the amounts of heat due to energy losses are pre¬ served: the exhaust heat directly and the cooling heat and friction heat via the part of the compressor air which is used as cooling gas. Since there is great freedom with regard to the selection of the thermo- dynamic characteristics of this low-pressure process, this can be tak-en very far with regard to efficiency ' , which provides the possibility of achieving ve ry high degrees of efficiency, particularly when a high-class internal combustfon engine is used. The pressurized air used for the cooling has a greater heat absorption capacity than cooling air at a lower pressure, which leads to a more effective cooling of an air-cooled ^ internal combustion engine and provides the possibility of using a smaller radiator without a fan in the case of a liquid-cooled internal combustion engine. The pressurized air <which is supplied to the internal combustion engine as com- bustion air, provides supercharging of the engine, the air pressure and air amount being adjusted a-s to the requirements of the engine. OMPI

Claims: CLAIMS 1. A method in operating an internal combustion engine (13) with an air compressor (10) driven thereby, which absorbs the total output of the engine, c h a r a c t e r i z e d in that a first part (15) of the pressurize^ a r from the compressor is supplied to the internal combustion engine . (13) as intake air, a second part (16--) is supplied to the* internal combustion engine as cooling air, and a third part (20) is shunted past the internal combustion engine to be supplied, together with t-h-e exhaust gases (17) from the engine and the cooling air (18), to a working machine (21) to be caused to expand therein while performing work. 2. A method as claimed in claim 1, c fr a r a c - t e r i z e d in that the exhaust gases (17), the cool¬ ing air (18) and the shunted pressurized air (20) are mixed with one another (in 19) before they are supplied to ' the worki ng. machi ne (21).

Inventors: ANDERBERG AOKE ELVIR, ANDERBERG, AOKE, ELVIR
Applicants: ANDERBERG AOKE ELVIR, ANDERBERG, AOKE, ELVIR
Application year: 1981
Main classification: F02C5
IPC codes: F02B1, F02C5, F02G3