A TURBO-CHARGING ARRANGEMENT IN COMBUSTION ENGINES

Abstract: A turbo-charging arrangement in internal combustion engines, comprising a first turbo unit (1) and a second turbo unit (2), said units being arranged to be positioned adjacent the engine (13). The first unit (1) is positioned above the second unit (2) and also closely adjacent the exhaust port of the engine (13).

Description: A TURBO-CHARGING ARRANGEMENT IN COMBUSTION ENGINES The subject invention concerns a turbo-charging arrangement in combustion engines comprising a first turbo unit and a second turbo unit intended to be placed adjacent a combustion engine. Turbo-charged combustion engines of today may be provided with one or seveal turbo units. Embodiments according to which one and the same turbo unit operates with air supplied to the engine and with exhaust flows from the engine over the entire operational range, normally require considerable time to build up the charging pressure under accelerating conditions at low rotational speeds. Devices arranged in serial sequence may provide good response properties with regard to the the charging pressure at low rotational speeds as well as good fuel economy during conditions of full charge. In this case, the entire mass of flow of air and exhaust gases passes through a small turbo unit under low-power requirement conditions and through a larger turbo unit under high- power requirement conditions. Devices designed for in-vehicle installment of sequentially positioned turbo-charging arrangements normally take up a considerable amount of the available space. In accordance with the invention is provided an arrangement for installing turbo units, air and exhaust ducts in an in-line engine in a compact manner while at the same time assuring flow conditions in the air and exhaust ducts that favour the turbo function. This arrangement is characterized in that the first turbo unit is positioned above the second turbo unit, and in that the first turbo unit is positioned closely adjacent the engine exhaust. The invention will be described in closer detail in the following with reference to a preferred embodiment and to the accompanying drawings, wherein Fig. 1 illustrates schematically the structural design of a turbo unit operating in serial sequence, Fig. 2 illustrates schematically a engine unit in a view from behind, and Fig. 3 illustrates the same engine unit in a lateral view. Fig. 1 illustrates a turbo-charging arrangement in accordance with the invention. It comprises a first turbo unit 1 and a second turbo unit 2, the latter one being larger than the first one. However, the size difference is not necessary. On the air intake side of the unit is provided a first regulating valve 3 which in this case is a non-return valve. On the exhaust side is provided a second, controllable regulating valve 4. A first waste-gate valve 5 is provided in the first turbo unit 1 and in the second turbo unit a second waste- gate valve 6, both of which are controllable. Closely adjacent the induction duct of the engine a rotary intake valve 7 is positioned, the opening and closing movements of which are controlled in response to the function of the "ordinary" conventional intake valve or valves 8. In the customary manner, exhaust valves 9 are provided at the cylinder head. Numeral reference 10 designates a sensor designed to measure the temperature of the exhausts. In addition, numeral reference 11 designates a revolution counter 11, and numeral reference 12 indicates the ordinary, conven¬ tional throttle valve. In a view from behind, Fig. 2 illustrates an internal combustion engine 13 and the turbo-charging arrangement associated therewith. The combustion engine 13 in this case is an in-line engine but other engine designs, such as e.g. V-engines are possible. The first turbo unit 1 is positioned adjacent the branch pipe of the engine 13. The second turbo unit 2 is positioned at the same side of the engine 13 as the first turbo unit 1 but below the latter. This disposition of the turbo units is advantageous as regards exhausts as well as the position of the turbo valve in the first unit 1. Positioning, as illustrated, the second unit 2 somewhat displaced to the left (see Fig. 3) in relation to the first unit 1 is an elegant solution of drawing the exhaust duct of the first unit 1 in a compact and space-saving manner. Fig. 3 shows the air and exhaust connections between the two turbo units 1, 2 and the valve 4. Owing to the arrangment in accordance with the subject invention the resulting complete engine unit will be compact as to its width with resulting reduced width requirement for installment thereof in the engine compartment. Furthermore, the arrangement furthers favour¬ able flow conditions as regards the turbo function, because of the use of short exhaust and air ducts, which is an advantage for both turbo units 1, 2. By avoiding long "distances of transportation" in the air and exhaust ducts the risks of temperature and pressure losses inside the ducts are reduced accordingly.

Claims: CLAIMS 1. A turbo-charging arrangement in combustion engines (13), comprising a first turbo unit (1) and a second turbo unit (2), which units are designed to be positioned adjacent an internal combustion engine (13), c h a r a c t e r i z e d in that the first unit (1) is positioned above the second unit (2), and in that the first unit (1) is positioned closely adjacent the exhaust port of the engine (13). 2. A turbo-charging arrangement as claimed in claim 1, c h a r a c t e r i z e d in that the two turbo units (1, 2) are placed in mutually displaced positions and in the longitudinal direction of the engine (13). 3. A turbo-charging arrangement as claimed in claim 2, c h a r a c t e r i z e d in that it comprises valves (3, 4, 5, 6) which are forcibly controlled in accordance with a predetermined control algorithm, said valves being arranged to provide a sequential function with continuous transitions. 4. A turbo-charging arrangement as claimed in claim 3, c h a r a c t e r i z e d in that the first unit (1) is smaller than the second unit (2) and, in comparison with the second unit (2), it is intended to be operated at a comparatively low rotational speed of/low load on the engine (13).

Inventors: BACKLUND OVE, RYDQUIST JAN-ERLING, SANDBERG LARS, BACKLUND, OVE, RYDQUIST, JAN-ERLING, SANDBERG, LARS
Applicants: VOLVO AB, AB VOLVO
Application year: 1991
Main classification: F02B37
IPC codes: F02B33, F02B37, F02B67