Abstract:
An internal combustion engine with a mechanically driven charge-air compressor, which is connected to the engine intake manifold by way of an intercooler, is disclosed. The characteristic feature of the engine is that the compressor, the intercooler and the intake manifold have a common, integrally cast housing part.

Description:
BACKGROUND OF INVENTION  
         [0001]    1. Technical Field  
           [0002]    The present invention relates to an internal combustion engine comprising an engine block with a plurality of cylinders, a cylinder head connected to the engine block with combustion air inlet ports to each cylinder, an intake manifold with at least one branch pipe to each cylinder and a mechanically driven compressor that is connected to the intake manifold by way of an intercooler.  
           [0003]    2. Background Information  
           [0004]    Supercharged engines with charge-air cooling usually have a radiator in the form of a plate heat exchanger mounted in the engine compartment at a distance from the engine. The heat exchanger is connected by way of pipes and/or hoses to the compressor outlet and the intake manifold inlet. This means that the volume of air between the compressor outlet and the intake manifold inlet is relatively large. When a mechanically driven compressor, such as a screw compressor, is used a great amount of noise tends to be generated due to resonance in the system. Further, this large volume of air between the compressor outlet and the inlet to the engine cylinders also has a negative effect on engine response.  
         SUMMARY OF INVENTION  
         [0005]    The object of the present invention is to produce a supercharged internal combustion engine having a very compact compressor and intercooler installation, resulting in more efficient cooling and silencing and improved response than previously known supercharged engines with charge-air cooling described above.  
           [0006]    According to the invention this is achieved by having a common, integrally formed housing part connected to the intake manifold for the compressor and the intercooler.  
           [0007]    In a preferred embodiment the intake manifold is also integrally formed with the housing part of the compressor and the intercooler. The housing part is preferably composed of a cast metal such as aluminum.  
           [0008]    By integrating the compressor, intercooler and intake manifold in this way, a very compact and stable unit is provided with very small air volume between the compressor outlet and the inlet into the cylinders of the engine. For example, the volume of air may be as little as 2.5 liters in an engine of corresponding cylinder capacity. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0009]    The invention is described in more detail below with reference to exemplary embodiments shown in attached drawings, in which:  
         [0010]    [0010]FIG. 1 shows an end perspective view of an embodiment of a multi-cylinder, in-line engine;  
         [0011]    [0011]FIG. 2 shows a side perspective view of the engine in FIG. 1;  
         [0012]    [0012]FIG. 3 shows a side perspective view of the engine&#39;s integrated compressor, intercooler and intake manifold unit;  
         [0013]    [0013]FIG. 4 shows the unit in FIG. 3 rotated 90 degrees;  
         [0014]    [0014]FIG. 5 shows an end perspective view of the unit in FIG. 3 viewed from the right end of FIG. 3;  
         [0015]    [0015]FIG. 6 shows an end perspective view of the unit in FIG. 3 viewed from the right but with its right end removed;  
         [0016]    [0016]FIG. 7 shows a cross-sectional view through the unit in FIG. 3;  
         [0017]    [0017]FIG. 8 a  shows a side view of a cooler element;  
         [0018]    [0018]FIG. 8 b  shows an end view of the cooler element in FIG. 8 a;    
         [0019]    [0019]FIG. 8 c  is an enlarged view of the area inside the circle A in FIG. 8 a ; and  
         [0020]    [0020]FIG. 9 shows a block diagram or schematic of an exemplary embodiment of a cooling circuit for the intercooler. 
     
    
     DETAILED DESCRIPTION  
       [0021]    In FIG. 1, 1 denotes the cylinder block,  2  the cylinder head and  3  the oil pan of a multi-cylinder in-line engine having fuel injection as known in the art. The engine has twin overhead camshafts supporting gears or pinions  4 . A common toothed belt  5  drives these pinions  4  from a pinion  6  on the engine crankshaft  6   a . An integrated compressor, inter-cooler and intake manifold unit, generally denoted by  7 , is shown on the right-hand side of the cylinder block  1  and the cylinder head  2  in FIG. 1. This integrated unit  7  will be described in more detail below, with particular reference to FIGS.  3 - 7 .  
         [0022]    The unit  7  has an integrally cast housing body  8 , preferably of aluminum, for housing a screw compressor  13  and an intercooler  14 . The housing body  8  is closed at the ends by various end pieces  9 ,  10  and  11 . As illustrated in FIG. 6, a housing part  15  encloses the rotating screws  15   a  of the compressor  13 . The axes  13   a  of those screws  15   a  are parallel with the engine crankshaft  6   a . An additional housing part  16  defines three cylindrical, elongated chambers parallel to the crankshaft  6   a  for cooler elements of the intercooler, described in more detail below. The housing part  16  of the intercooler merges into an intake manifold  18  with one or more intake pipes  19 , which is therefore integrally cast with the compressor and intercooler housing parts  15  and  16 . The intake pipes  19  are preferably designed with threaded seats  20  or like seats  20  for fuel injectors (not shown). Air is drawn into the housing part  15  of the compressor  13  through an inlet pipe  21  connected to a line with an air filter. The compressed air flows through an outlet  22  from the compressor (see, FIG. 7) into an enclosed space  23 , which is separated from the interior  24  of the manifold  18  by one or more (here, three) cast-in cylinders  25  with intervening wall elements  26 .  
         [0023]    The cylinders  25  define the above-mentioned cylindrical chambers  17  and are arranged so that each encloses a cooler element in the form of a pipe with external cooling flanges. In a preferred embodiment, cooling fins  27  of a type known in the art are used, such as shown in FIGS. 8 a - 8   c . Examples of such fins  27  that are commercially available are marketed under the name Laminovastavar. The walls of the cylinders  25  are perforated by slits  28  and  29  distributed along the length of the cylinders. This allows air that is forced into the enclosed space  23  to flow in through the slits  28 , pass between cooling gills  30  of the fins  27  and flow out through the slits  29  into the intake manifold  18 .  
         [0024]    In a vehicle with air conditioning system, the refrigerant of the air conditioning system is preferably used for cooling the cooling fins  27 . FIG. 9 diagrammatically illustrates such a conventional cooling system having a compressor  40 , storage reservoir,  41 , cooler element  42  and condenser  43  for cooling the cooling fins. The cooling circuit  44  for the cooling fins  27  is connected in parallel with the cooler element  42 . In addition to the fins  27 , the circuit  44  comprises a throttle  45 , an electrically controlled valve  46  and a storage reservoir  47 .  
         [0025]    In the embodiment shown in FIGS. 1 and 2, the air conditioning system cooling compressor  40  is suspended in the housing  8  of the compressor, intercooler and intake manifold unit  7 . A power steering hydraulic pump  48  is also fitted in the housing. By suspending the cooling compressor  40  in the housing  8 , short lines will suffice for carrying refrigerant to the cooling fins  27  of the intercooler. The embodiment described enables the charge-air compressor  13 , the cooling compressor  40  and the hydraulic pump  48  to be driven by the same drive belt from the engine crankshaft, as indicated by the dotted and dashed line  49  in FIG. 1.  
         [0026]    Altogether, the embodiment described provides an extremely compact and stable installation that affords very efficient cooling, low noise level and good response.  
         [0027]    The invention has been described above with reference to an installation with a screw compressor, but it is also feasible to use other types of mechanically driven compressors, such as a Roots Compressor. Nor is the invention confined to cooling of the cooling fins  27  using the refrigerant in an air conditioning system. Without departing from the scope of the invention, the cooling fins  27  may alternatively be cooled by coolant, which is in turn cooled in an air-cooled heat exchanger.  
         [0028]    While there has been disclosed effective and efficient embodiments of the invention using specific terms, it should be well understood that the invention is not limited to such embodiments as there might be changes made in the arrangement, disposition, and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.