GB1583060A

GB1583060A - Internal combustion engine with an exhaust-gas driven super-charger and a charge-air cooler

Info

Publication number: GB1583060A
Application number: GB5333277A
Authority: GB
Original assignee: MAN Maschinenfabrik Augsburg Nuernberg AG
Current assignee: MAN AG
Priority date: 1976-12-23
Filing date: 1977-12-21
Publication date: 1981-01-21
Also published as: FR2375452A1; NL7714007A; DD132989A1; DK572577A; JPS5390516A; JPS6060012B2; DK145390B; DE2658375A1; IT1090826B; BR7708558A; DE2658375C2; ES464350A1; DK145390C; FR2375452B1

Description

(54) IMPROVEMENTS RELATING TO AN INTERNAL COMBUSTION ENGINE WITH AN EXHAUST-GAS DRIVEN SUPER-CHARGER AND A CHARGE-AIR COOLER (71) We, MASCHINENFABRIK AUGSBERG- NURNBERG AKTIENGESELLSCHAFT a German company, of 8900 Augsburg, Stadtbachstrasse 1, Germany, (Fed.Rep.), do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the fol lowing statement:- This invention relates to an internal com bustion engine with an exhaust-gas driven super-charger, including a duct connecting the outlet of a compressor of the super charger supplying charge air to the inlet of a charge-air cooler which may be disposed on the engine; the invention also relates to such a supercharger connected by a duct to a charge - air cooler, and to such a duct.

In known exhaust-gas driven super chargers (see for example M.A.N. publica tion D 36 5128 "Medium-speed four stroke heavy-oil engines", Page 68, bottom illustra tion), the charge air emerging from the compressor at high velocity with a strong swirl is fed to a charge-air cooler inlet arranged substantially at right angles to the direction in which the air leaves the compressor, as may be necessary in modern engines for reasons of compact design.

Deflection of the charge air and sudden widening of the connecting duct give rise to severe flow losses, impairing uniform distribution of air over the cooler surface and thus leading to incomplete utilization of the cooler and to additional flow losses.

Although baffle plates altering the direction of flow of the charge air to the cooler have been used to improve flow conditions, such measures have the disadvantage that the baffle plates represent a further flow resist ence in the cross-sectional flow area in addition to the pipe bend and lead to severe turbulence, since the flow of air and its strong swirl result in a strong flow com ponent acting in the peripheral direction of the connecting duct.

An object of the invention is to reduce flow losses as the charge air leaves the com pressor and to ensure more uniform distribution of the air over the cooler inlet surface.

According to one aspect of the present invention, there is provided an internal combustion engine with an exhaust-gas driven super-charger, including a duct connecting the outlet of a compressor of the super-charger supplying charge air to the inlet of a charge-air cooler, in which at least that part of the connecting duct adjoining the compressor outlet is a diffuser of circular or oval cross-section in which a second diffuser of circular or oval cross-section is concentrically arranged, the ratio of the diameters of the inlet and the outlet of which to those of the inlet and outlet of the outer diffuser being such that approximately equal velocities prevail at both outlets.

If this arrangement is applied, the pressure of the charge air can fall over a very short distance, so that the air, on leaving the diffusers with reduced velocity and correspondingly lower flow losses, can be fed to the charge-air cooler even under conditions of restricted geometry. Moreover, the diffuser walls present negligible resistance to the flow of charge air and the strong swirl attendant upon it since those walls extend in the direction of the swirl component. The pressure of the charge air can therefore be reduced as it passes through the diffuser without any considerable dissipation of energy by turbulence. A further advantage is that the air flows into the charge-air cooler with a uniform distribution of energy, thus improving the efficiency of the cooler.

In an advantageous embodiment of the invention, the inner diffuser is longer than the outer diffuser. On the one hand distribution of the air over the inlet surface of the cooler can thus be improved even further, and on the other hand, an optimum angle of expansion can be selected for retardation of the air in the inner diffuser since long diffusers are invariably superior to short diffusers with the same cross-sectional ratio. Depending on the specific geometry used, total efficiency can thus be improved over that of two diffusers of the same length.

In accordance with a further preferred feature, the inner, longer diffuser can be attached at its outlet to a partition running the length of the duct leading to the chargeair cooler. This arrangement dispenses with fastenings in the outer diffuser to secure the inner diffuser, making for smoother flow and obviating interference factors inducing flow losses.

According to a second aspect of the invention, there is provided a duct for connecting the outlet of a compressor of an exhaust-gas driven super-charger for an internal combustion engine to the inlet of a charge-air cooler in which at least that part of the duct arranged to adjoin the compressor outlet is a diffuser of circular or oval cross-section in which a second diffuser of circular or oval cross-section is concentrically arranged, the ratio of the diameters of the inlet and outlet of which to those of the inlet and outlet of the outer diffuser being such that, in use, approximately equal velocities prevail at both outlets.

According to a third aspect of the invention, there is provided an exhaust-gas driven super-charger for an internal combustion engine connected to a charge-air cooler by such a duct.

The invention may be carried into practice in a number of ways but two specific embodiments will now be described, by way of example, with reference to the accompanying drawing, in which: Figure l is a schematic sectional view of a duct comprising a diffuser attached at one end to a compressor outlet and at the other to a passage leading to a charge-air cooler; and Figure 2 is a section through a diffuser of another embodiment taken in a plane at right angles to that of the embodiment depicted in Figure 1.

In the embodiment depicted in Figure 1, the outlet 1 of a compressor, not illustrated, is attached to a diffuser 2 widening towards the bottom in the shape of a cone frustum.

A flange 3 arranged on the compressor outlet 1 is connected to a flange 4 attached to the top rim of the diffuser 2. An inner diffuser 5 is concentrically arranged inside the outer diffuser 2, the inner diffuser being secured to the outer diffuser by fastenings 6. The inner diffuser 5 incorporates an inlet 7 and an outlet 8, the ratio of the diameters of which to those of the corresponding annular inlet 9 and outlet 10, of circular or oval shape, of the outer diffuser 2 being such that approximately equal velocities prevail at both outlets 8 and 10.

In the special configuration of the diffusers 2 and 5, it must be borne in mind on the one hand that the distribution of energy varies at the two diffuser inlets 7 and 9 and, on the other, that the wall surfaces of the outer diffuser 2 are substantially larger than those of the inner diffuser 5 and thus cause greater frictional resistance.

Diffusers 2 and 5 form two flow ducts 11 and 12 respectively, duct 11 having an annular cross-section. A flange 13 is fastened to the outlet 10 of the outer diffuser 2 and connects the diffuser 2 to an inlet duct or passage 14 leading to a charge-air cooler 15. The inlet duct 14 is connected by a flange 16 to the inlet side 17 of the chargeair cooler 15. In the embodiment depicted in Figure 1, the diffusers 2 and 5 terminate at the inlet to the duct 14. However, embodiments are possible in which, depending on the given space, the diffusers 2 and 5 partly project into the inlet duct 14 or in which the flange of the compressor outlet 1 is directly attached to the inlet duct 14, with the duct 14 completely containing the diffusers 2 and 5.Embodiments are even conceivable in which the diffusers 2 and 5 project obliquely into the inlet duct 14 at an acute angle to the longitudinal axis of the duct 14.

The air supplied by the compressor flows at high velocity and with a strong swirl through the outlet 1 into the diffusers 2 and 5. The air current is divided on entering the diffuser; some of the air flows through the annular inlet 9 into the flow duct 11 and the rest of the air through the inlet 7 into the flow duct 12. The pressure of the charge air falls as it passes through the two ducts 11 and 12 owing to the conical widening of the ducts in the flow direction, some of the dynamic pressure of the air being converted into static pressure. The charge air thus emerges from the outlets 8 and 10 at reduced velocity, the velocity of the air being approximately the same from each outlet 8 and 10, and is fed in this condition to the inlet 17 of the charge-air cooler 15 with only slight flow losses. The inlet 17 may be in a plane parallel to the plane of the compressor outlet or at right angles to it as shown in Figure 1.

In the embodiment depicted in Figure 2, the inner diffuser 5 is longer than the outer diffuser 2. The outlet 8 of the inner diffuser 5 is fastened by a flange 18 to a horizontal partition 19 in the inlet duct 14 leading to the charge-air cooler 15. This embodiment dispenses with the fastenings 6 for the inner diffuser 5 as used in the embodiment shown in Figure 1, so that the charge air flowing through the flow duct 11 is not impeded by any flow resistances.

With reference to the embodiment depicted in Figure 2, arrangements are also possible in which, depending on the given space, the outer diffuser 2 projects partly or entirely into the inlet duct 14.

In variants of the illustrated embodiments, the flow duct direction at the inlets to the inner and outer diffusers may be parallel to the flow duct direction at the inlet to the cooler.

WHAT WE CLAIM IS: 1. An internal combustion engine with an exhaust-gas driven super-charger, including a duct connecting the outlet of a compressor of the super-charger supplying charge air to the inlet of a charge-air cooler, in which at least that part of the connecting duct adjoining the compressor outlet is a diffuser of circular or oval cross-section in which a second diffuser of circular or oval cross-section is concentrically arranged, the ratio of the diameters of the inlet and outlet of which to those of the inlet and outlet the outer diffuser being such that approximately equal velocities prevail at both outlets.

2. An internal combustion engine as claimed in claim 1, in which the inner diffuser is longer that the outer diffuser.

3. An internal combustion engine as claimed in claim 2, in which the outlet of the inner diffuser is fastened to a partition across an inlet duct leading to the charge-air cooler.

4. An internal combustion engine as claimed in any one of claims 1 to 3, in which the flow duct direction at the inlets to the inner and outer diffusers is parallel to the flow duct direction at the inlet to the cooler.

5. An internal combustion engine as claimed in any one of claims 1 to 3, in which the diffusers open at their downstream ends into an inlet passage to the cooler, the flow duct direction through the inner and outer diffusers being perpendicular or inclined at an acute angle to the flow duct direction through the inlet passage to the cooler.

6. An internal combustion engine as claimed in claim 5, in which the diffusers project partly or wholly into the inlet passage to the cooler.

7. An internal combustion engine as claimed in claim 5 or claim 6, in which, at the inlets to the diffusers, the duct is connected by a first flange to the outlet of the compressor and the downstream end of the inlet to the cooler is connected to the cooler inlet by a second flange, the first and second flanges lying in mutually perpendicular planes.

8. A duct for connecting the outlet of a compressor of an exhaust-gas driven super charger for an internal combustion engine to the inlet of a charge-air cooler, in which at least that part of the duct arranged to adjoin the compressor outlet is a diffuser of circular or oval cross-section in which a second diffuser of circular or oval cross-section is concentrically arranged, the ratio of the diameters of the inlet and outlet of which to those of the inlet and outlet of the outer diffuser being such that, in use, approximately equal velocities prevail at both outlets.

9. A duct as claimed in claim 8, in which the inner diffuser is longer than the outer diffuser.

10. A duct as claimed in claim 8 or 9, in which, in use, the flow duct direction at the inlets to the inner and outer diffusers is parallel to the flow duct direction at the inlet to the cooler.

11. A duct as claimed in claim 8 or 9, in which the diffusers open at their downstream ends into an inlet passage for connection to the cooler, the flow duct direction through the inner and outer diffusers being perpendicular or inclined at an acute angle to the flow direction through said inlet passage.

12. A duct as claimed in claim 11, in which the diffusers project partly or wholly into said inlet passage.

13. A duct as claimed in claim 11 or 12, provided at the inlets to the diffusers with a first flange for connection to the outlet of the compressor, and at the downstream end of said inlet passage with a second flange for connection to the cooler inlet, the first and second flanges lying in mutually perpendicular planes.

14. An exhaust-gas driven supercharger for an internal combustion engine, connected to a charge-air cooler by a duct as claimed in any one of claims 8 to 13.

15. A duct for connecting the outlet of a compressor of an exhaust-gas driven super

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. inner and outer diffusers may be parallel to the flow duct direction at the inlet to the cooler. WHAT WE CLAIM IS:

1. An internal combustion engine with an exhaust-gas driven super-charger, including a duct connecting the outlet of a compressor of the super-charger supplying charge air to the inlet of a charge-air cooler, in which at least that part of the connecting duct adjoining the compressor outlet is a diffuser of circular or oval cross-section in which a second diffuser of circular or oval cross-section is concentrically arranged, the ratio of the diameters of the inlet and outlet of which to those of the inlet and outlet the outer diffuser being such that approximately equal velocities prevail at both outlets.

charger for an internal combustion engine to a charge-air cooler, substantially as specifically described herein with reference to Figure 1 or Figure 2 of the accompanying drawing.

16. An exhaust-gas driven super-charger for an internal combustion engine, the compressor outlet of which is connected to a charge-air cooler by a duct as claimed in claim 15.

17. An internal combustion engine having an exhaust-gas driven super-charger as claimed in claim 16.