Abstract:
A crankcase breathing system ( 1 ) for an internal combustion engine includes at least one oil separating apparatus with a preliminary separator ( 3 ) and a main separator ( 4 ) arranged downstream of the same, with the preliminary separator ( 3 ) including a diffuser ( 11 ) between an inlet ( 7 ) and an outlet ( 8 ) which expands in the direction of flow. In order to achieve high separation rates in the simplest possible way it is provided that the preliminary separator ( 3 ) is arranged integrally with the main separator ( 4 ), with preferably the preliminary separator ( 3 ) and the main separator ( 4 ) forming a separator unit ( 2 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a crankcase breathing system for an internal combustion engine, comprising at least one oil separating apparatus with a preliminary separator and a main separator arranged downstream of the same, with the preliminary separator comprising a diffuser between an inlet and an outlet which expands in the direction of flow. The invention further relates to a liquid-cooled internal combustion engine with a crankcase for several cylinders with a cooling jacket about the cylinders in the crankcase, with individual cylinder heads with at least two cooling chambers arranged above one another in the cylinder head, with the cooling jacket of the crankcase and the bottom cooling chamber in the cylinder head being connected with each other via at least one, preferably at least four, transfer openings which are evenly distributed on the circumference of the cylinder. The invention also relates to a multi-part pulley, especially a poly-V pulley. The invention further also relates to an internal combustion engine with an oil pump whose feed pressure can be limited by a control valve, with the control valve having a spring-loaded control piston which is displaceable in the control cylinder, and with a gradual-removal chamber formed by control piston and control cylinder being connected with an oil return line. 
     2. The Prior Art 
     An oil preliminary separator is known from AT 006.652 U1 which can be provided upstream of a main oil separator in a crankcase breathing system. The preliminary separator comprises a diffuser between inlet and outlet which expands in the direction of flow. High separation rates can thus be achieved. 
     DE 31 07 191 A1 describes a crankcase breathing system for an internal combustion engine, comprising a funnel-like liquid separator which comprises a separator packing and an upwardly facing screen. An annular collecting chamber for separated liquid is arranged in the area of the transition to a downwardly arranged breathing line. The lowest point of the annular collecting chamber is the starting point for a liquid discharge line which is arranged in the interior of the breathing line, reaches back up to the crankcase and is guided here into a steadied-flow zone. 
     FR 2 332 424 A discloses an oil separator for an internal combustion engine which comprises a double cone between the inlet and outlet, which double cone expands in a first section in a diffuser-like way. This is then followed by a funnel-like section in which the cross section tapers until the discharge from the oil separator. A number of baffle plates is arranged in the oil separator which improve the separation of the oil. The entrainment of especially small oil drops still cannot be prevented in the case of especially high flow quantities. 
     A cylinder head for several cylinders for a liquid-cooled internal combustion engine is known from AT 005.301 U1, comprising a cooling chamber arrangement adjacent to a fire deck which is subdivided into a fire-deck-side bottom partial cooling chamber and an upper partial cooling chamber adjacent thereto in the direction of the cylinder axis by an intermediate deck extending substantially parallel to the fire deck. The bottom and upper partial cooling chamber are flow-connected with each other via an annular overflow opening about an injection device. The coolant reaches the bottom partial cooling chamber through at least one inlet bore per cylinder arranged in the fire deck, flows through the same in the transversal direction and reaches the upper partial cooling chamber through the annular overflow opening. 
     DE 103 12 190 A1 discloses a crankcase with wet liners which are enclosed by cooling chambers. The cooling chambers are in connection with a distributor duct arranged in the area of a longitudinal side wall of the crankcase, above which a collecting duct is arranged. 
     Poly-V belts are especially suitable for transmitting drive and tension forces at high belt speeds and minute disk diameters and have especially favorable running and transmission properties. Highly flexible poly-V belts are described in DD 270 117 A1 for example. 
     Furthermore, a drive device for an auxiliary machine unit with a driven poly-V pulley is known from DE 102 00 686 A1. 
     As a result of the small dimensioned poly-V belt application surfaces, poly-V belts are more sensitive to dirt, rust and porous frictional surfaces in the grooves than known narrow V-belts. Poly-V pulleys therefore must offer high surface quality in the area of the belt application surfaces. Especially in the case of poly-V belt disks arranged in several steps, a considerable production effort is required for achieving high surface quality. 
     Multi-part pulleys for simple belts are known from EP 0 100 756 A1 or U.S. Pat. No. 4,193,310 A. The pulley consists of two mutually connected disk holding parts, with the receiving surfaces for the belts being formed by both disk holding parts. 
     EP 0 875 678 A2 discloses an oil pump with a control valve, with the control valve comprising a control piston displaceable in a cylinder. The control pressure is formed by the pump pressure applied directly onto the pressure side of the pump. The oil is supplied to a main intake opening or an ancillary intake opening of the pump depending on the pump pressure. 
     In the case of oil pumps with gradual removal into the suction chamber, the desired oil pressure in the main oil duct is achieved in that the spring of the control valve in the oil pump is set higher by the flow resistances of the downstream oil cooler and oil filter. The disadvantageous aspect is that especially in the case of cold starting the oil pressure build-up is delayed. 
     It is the object of the invention to avoid these disadvantages and to achieve optimal oil separation with the lowest possible effort in all operating ranges of the internal combustion engine. It is a further object to achieve an optimal and even cooling of thermally critical areas. It is also an object of the invention to provide a pulley that can be produced in a cost-effective way. It is further an object of the invention to enable rapid oil pressure build-up especially during cold starting. 
     SUMMARY OF THE INVENTION 
     It is provided according to the invention that the preliminary separator is arranged integrally with the main separator, with preferably the preliminary separator and the main separator forming a separator unit. An especially cost-effective production can be enabled by the integral arrangement. 
     Especially high separation rates are achieved when the main separator is formed by a cyclone separator, preferably a multi-cyclone separator, with the outlet of the preliminary separator being arranged in a tangential way relative to the main separator. Moreover, the oil separation in the preliminary separator can be improved substantially when at least one baffle plate is arranged between the inlet and the outlet of the preliminary separator, with preferably the baffle plate having a shape which is round, elliptical, rectangular, square or composed of arcs of a circle. 
     It is provided within the framework of the invention that the baffle plate is spaced from the outlet of the preliminary separator, with the distance between the baffle plate and the outlet being determined depending on the maximum quantity of blow-by gas and with the distance being arranged smaller with increasing quantity of blow-by gas. 
     It is preferably provided that an outlet opening for the separated oil is arranged in the area of the largest cross section of the diffuser and at the lowest point of the housing. The diffuser leads to a reduction in the speed which prevents an entrainment of the oil film. The oil of the wall film flows as a result of gravity to the lowest point where the outlet opening is placed. A portion of the fine particles in the blow-by gas collects on the baffle plate into larger drops and they then fall onto the conical jacket surface of the diffuser and flow further to the outlet opening. 
     Especially good oil separation rates can be achieved when a substantially annular inlet part is arranged in the area of the outlet for the blow-by gas, which inlet part protrudes into the interior of the housing, preferably in the area of the largest cross section of the diffuser. 
     A very compact arrangement of the preliminary separator can be achieved when inlet, outlet, diffuser and/or inlet part are provided with a rotationally symmetrical configuration, wherein preferably the inlet, outlet, diffuser and/or inlet part can be arranged coaxially. It is also possible to arrange inlet, outlet, diffuser and/or inlet part in an offset manner relative to each other. As an alternative to a rotationally symmetrical shape, the preliminary separator can also be arranged as a truncated pyramid with an elliptical, square, rectangular or polygonal cross section. 
     The preliminary separator is especially suitable for installation with horizontally arranged longitudinal axis. 
     Especially favorable results can be achieved when the diffuser has an opening angle of not more than 30°, preferably between 10° and 20°, as measured with respect to the longitudinal axis. 
     It is well known that blow-by gas should be taken at the quietest possible location of the internal combustion engine, far from producers of oil mist and oil splashes. The lines should be dimensioned as large as possible in order to avoid high gas flow velocities and to prevent the entrainment of larger oil drops. These requirements cannot always be fulfilled, so that too small removal points in the cross section cannot be avoided. In order to prevent the entrainment of larger oil drops, it is provided within the scope of the invention that the preliminary separator is provided upstream with a calming chamber, with one, preferably at least two, crankcase breathing lines connected with the crank chamber opening into the calming chamber. Several withdrawal lines of smaller diameter can open into said calming chamber. It is further possible that a breathing line connected with the outlet of the main separator crosses the calming chamber. 
     It is preferably provided that the calming chamber comprises an oil return connection at its lowest point. The oil returns of the preliminary separator, the main separator and optionally also the calming chamber can open into a common oil return line. 
     The collected oil can be guided back to the oil pan, especially beneath the oil level, by suitable shaping. A return to the crankcase is also possible by using non-return valves. 
     In order to achieve optimal and even cooling of thermally critical areas, it is provided that the inlet distributor chamber is connected with the cooling jacket of the crankcase for a preferably dry liner via at least one connecting duct per cylinder, with preferably each connecting duct, when seen in a plan view, opening in a substantially radial manner into the cooling jacket with respect to the cylinder. The radial inflow is highly relevant in order to achieve even cooling of the cylinders. 
     It is further advantageous for even cooling when the connecting duct is arranged between a main oil duct and a return duct connecting the cooling chambers of the cylinder head with the return collecting chamber. 
     It is preferably provided that the inlet distributor chamber and/or return collecting chamber are arranged integrally with the crankcase, with preferably the inlet distributor chamber and/or the return collecting chamber extending over all cylinders arranged in a row. The number of parts and the sealing surfaces can thus be minimized and the coolant can be distributed among all cylinders evenly. This may be supported on a case by case basis by changes in the cross section of the individual inlets. 
     In order to reduce noise emissions of the crankcase to the ambient environment it is advantageous when the outside wall of the crankcase is curved in a convex manner to the outside in the area of the inlet distributor chamber and/or the return collecting chamber, with preferably the inlet distributor chamber and/or the return collecting chamber having a substantially semicircular cross section. 
     It is provided in an advantageous embodiment of the invention in which both the inlet distributor chamber and the return collecting chamber are arranged in the crankcase that the return collecting chamber is arranged above the inlet distributor chamber. In order to achieve optimal flow in thermally critical regions of the crankcase and inflow into the cylinder head it is advantageous when the inlet distributor chamber is connected via at least one connecting duct with the water jacket of the crankcase, with the inlet opening of the connecting duct from the inlet distributor chamber being arranged lower for each cylinder in the installed position of the internal combustion engine than the outlet opening into the cooling jacket. The coolant enters from the inlet distributor chamber via the distributor duct facing upwardly inclined into the cooling jacket. When seen in a plan view, said distributor duct faces radially to the cylinder. Intense cross-flow cooling shall thus be achieved in the upper hot region of the cylinder. 
     In order to achieve optimal cooling of the fire deck of the cylinder head, it is especially advantageous when an intermediate deck is arranged in the cylinder head between the bottom and the top cooling chamber, with the deck surface of the bottom cooling chamber formed by the intermediate deck being lowered in at least one region in such way that the coolant flow is deflected in the direction of the fire deck. As a result of the deck surface curved downwardly in a convex manner, the coolant is deflected in the direction of the fire deck. An efficient cooling can thus also be achieved between the individual intake and exhaust ports, especially between the valve reinforcing ribs. 
     In a further embodiment of the invention it is provided that in the area of a centrally arranged injector at least one transfer opening is arranged between the bottom and the upper cooling chamber, with the transfer opening preferably being formed by an annular gap at least in sections between the intermediate deck and an injector sleeve. The coolant transfers into the upper cooling chamber of the cylinder head around the centrally arranged nozzle holder. The central arrangement of the transfer leads in combination with the position of the four transfers to a highly efficient cooling even between the individual ducts. 
     The coolant flows out again from the upper water chamber of the cylinder head through a vertically aligned rectangular or triangular opening adjacent to the exhaust port via the tappet chamber in which pressed-in pipes seal off towards the push rods into the return duct in the crankcase. 
     It can further be provided that an oil cooler is arranged upstream of the inlet distributor chamber in the cooling circulation, with preferably the longitudinal axis of the oil cooler being arranged in an inclined manner relative to the cylinder head sealing plane at a longitudinal side of the crankcase. 
     In a further embodiment of the invention it can be provided that at least one cast slug is arranged on the coolant discharge side of the oil cooler and that an inlet into the inlet distributor chamber is curved in a convex manner at the bottom end of the oil cooler chamber. 
     A cost-effective pulley can be produced when the pulley consists of a belt part which is preferably arranged as a hollow cylinder and a hub part which is torsionally rigidly connected with the same, with the hub part being arranged at least partly within the belt part. A durable rotational connection that is easy to produce is achieved when the hub part and the belt part are connected with each other by a pressed joint and/or a shrink joint. 
     It is preferably provided that the belt part is made of steel and that the hub part consists of a casting material. Belt receiving surfaces with high surface quality can be produced in a cost-effective way by the division of material between belt part and hub part. The pulley which consists of forged steel ensures that the belt receiving surface can be kept pore-free. The hub part can consist of a casting material which enables cost-effective production despite more complex shaping. 
     In a preferred embodiment it is provided that the belt part is provided with a stepped arrangement and comprises at least two belt receiving surfaces with different diameters. 
     It is especially advantageous when a vibration damper is rotationally connected with the hub part. In order to achieve sufficient cooling for the vibration damper, it can be provided with ventilating elements. It is further advantageous for improving cooling of the vibration damper when the hub part comprises at least one axial flow opening for cooling air. The coolant reaches the vibration damper via the flow openings in the hub part and flows supported by the ventilating elements between pulley and vibration damper radially to the outside, with the surface of the vibration damper being cooled. 
     In order to achieve a rapid oil pressure progression during cold starting it is advantageous when a control line which opens into the control chamber and is supplied with the control pressure is connected with the main oil duct of the internal combustion engine. The control pressure line preferably branches off from the lubricating oil system downstream of the oil cooler and/or the oil filter. A return line which is connected with the return opening preferably leads to an oil collecting chamber, with the opening of the return line being arranged beneath the oil level. In this way, oil foaming during the gradual removal of the quantity of lubricating oil not required by the internal combustion engine can be avoided. It is provided that one of the removal openings of the control valve is connected with a pressure duct of the pump. 
     In addition to the control valve, it is possible to provide a pump safety valve which is set to a considerably higher removal pressure. 
     The oil not required is guided in a purposeful manner to the oil pan close to the intake point, preferably via a return duct formed by a bent pipe. 
     The control valve and/or the pump safety valve may be integrated in the housing of the pump. 
     The invention will now be explained in greater detail by reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a crankcase breathing system in accordance with the invention in a first view; 
         FIG. 2  shows the crankcase breathing system in a second view; 
         FIG. 3  shows the crankcase breathing system in a top view; 
         FIG. 4  shows a separator unit of the crankcase breathing system in accordance with the invention in an oblique view in a first embodiment; 
         FIG. 5  shows the separator unit in a side view; 
         FIG. 6  shows the separator unit in a top view; 
         FIG. 7  shows the separator unit in a sectional view along line VII-VII in  FIG. 6 ; 
         FIG. 8  shows a separator unit of a crankcase breathing system according to the invention in a second embodiment in a side view; 
         FIG. 9  shows this separator unit in a top view; 
         FIG. 10  shows the separator unit in a sectional view along line X-X in  FIG. 9 ; 
         FIG. 11  shows an internal combustion engine in a cross-sectional view; 
         FIG. 12  shows a crankcase of this internal combustion engine in an oblique view; 
         FIG. 13  shows the crankcase in a side view; 
         FIG. 14  shows the crankcase in a sectional view along line XIV-XIV in  FIG. 15 ; 
         FIG. 15  shows the crankcase in a sectional view along line XV-XV in  FIG. 14 ; 
         FIG. 16  shows a cylinder head in a cross-sectional view; 
         FIG. 17  shows the cylinder head in a cross-sectional view along line XVII-XVII in  FIG. 16 ; 
         FIG. 18  shows a pulley in accordance with the invention in a longitudinal sectional view; 
         FIG. 19  shows the hub part of the pulley in a sectional view along line XXIX-XXIX in  FIG. 20 ; 
         FIG. 20  shows the hub part in a side view along arrow XX in  FIG. 19 ; 
         FIG. 21  shows the hub part in a sectional view along line XXI-XXI—in  FIG. 20 ; 
         FIG. 22  shows the hub part in a side view along arrow XXII in  FIG. 21 ; 
         FIG. 23  shows a pump of an internal combustion engine in accordance with the invention in a side view; 
         FIG. 24  shows the pump in a sectional view along line XXIV-XXIV in  FIG. 23 ; 
         FIG. 25  shows the pump in a side view, and 
         FIG. 26  schematically shows the oil circulation of the internal combustion engine in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Parts with the same function are provided with the same reference numeral. 
     The crankcase breathing system  1  as shown in  FIGS. 1 to 3  comprises a separator unit  2  which consists of a preliminary separator  3  and a main separator  4 . The separator unit  2  is shown in detail in  FIGS. 4 to 7 . The housing  5  of the preliminary separator  3  and the housing  6  of the main separator  4  are arranged integrally, which thus allows cost-effective production. The main separator  4  can be arranged as a cyclone separator with integrated nonwoven separator and with a pressure control valve provided upstream of the gas outlet. Furthermore, the main separator  4  can also be arranged as a multi-cyclone separator or as an electric system. 
     The preliminary separator  3  comprises an inlet  7  for a crankcase breathing line  9  and an outlet  8  which opens tangentially into the main separator  4 . An outlet opening  10  is arranged at the lowest point of housing  5  of preliminary separator  3 , to which opening an oil return line can be connected (not shown in closer detail). Housing  5  is arranged as a diffuser  11  opening in the direction of flow P between the inlet  7  and the outlet  8 . The opening angle α opened between diffuser  11  and the longitudinal axis  5   a  of housing  5  is approximately between 5° and 30°, and approximately 15° in the embodiment. 
     Outlet  8  has a tubular inlet part  12  which protrudes into the interior of housing  5  and is arranged approximately in the region of the largest cross section of diffuser  11 . 
     As is indicated with arrows P in  FIG. 7 , the crankcase breathing flow reaches diffuser  11  through inlet  7  and leaves the same again through outlet  8 . A baffle plate  13  is arranged between inlet  7  and outlet  8  in order to improve the degree of separation. Baffle plate  13  can have a shape which is round, elliptical, rectangular, square or composed of arcs of a circle and can be adjusted in its longitudinal position to the needs of the engine. 
     Inlet  7  has a larger diameter D 1  than the outlet  8  whose diameter is designated with reference numeral D 2 . As a result of the pressure drop caused by the diffuser  11 , oil droplets will form on the walls  11   a  of diffuser  11  and form an oil wall film, as indicated by reference numeral F. Diffuser  11  leads to a reduction in speed which prevents any entrainment of the oil wall film F. The oil of the oil wall film F flows to the lowest point as a result of gravity where the outlet opening  10  is positioned. A portion of the fine particles in the blow-by gas collects on the baffle plate  13  into larger drops. They then fall onto the conical jacket surface of diffuser  11  and then continue to flow further towards the outlet opening  10 . The oil leaves housing  5  via the outlet opening  10  in order to be supplied again to the lubrication circulation of the internal combustion engine. The blow-by gases then further reach the main separator  4  through the outlet  8 , with a swirling motion being produced by the tangential inlet. As a result of the inertia of masses, the oil droplets are separated on the walls  6   a  of housing  6  and leave the main separator  4  via the oil return connection  14  which is arranged at the lowest point of housing  6 . The blow-by gases leave housing  6  via a gas outlet  15   a  arranged in the upper region of housing  6  and a breathing line  15  connected to the same. The gas outlet  15   a  can also be provided upstream with a pressure control valve (for positive or negative crankcase pressure). 
     In the embodiment shown in  FIGS. 4 to 6 , the main separator  4  comprises fastening elements  16  with which the crankcase breathing system can be fastened to the machine housing. 
     The embodiment shown in  FIGS. 8 to 10  differs from the embodiment described above in such a way that the preliminary separator  3  is provided with fastening elements instead of the main separator  4 . The remaining description of  FIGS. 4 to 7  applies to this embodiment as well. 
     In addition to the separator unit  2 , a calming chamber  17  can be provided, as is shown in  FIGS. 1 to 3 . Calming chamber  17  prevents that larger oil drops will reach the separator unit  2 . Several crankcase breathing lines  18 ,  19  of smaller diameter can open into the calming chamber  17 , which breathing lines will remove blow-by gases from the crankcase. In the illustrated example, the breathing line  15  originating from the main separator  4  crosses the calming chamber  17  for constructional reasons. 
     Calming chamber  17  comprises an oil return connection  20  at its lowest point, through which the collected oil can be supplied to the oil pan again beneath the oil level. As an alternative to this, the entire oil can also be returned via non-return valves to the crankcase or into the front crank cover for example. 
     The oil return lines of preliminary separator  3  and the main separator  4  can be combined into a common oil return duct which opens into the oil pan or, via non-return valves, into the crankcase. 
     The described crankcase separating system allows for especially high separation rates with minimal constructional and structural effort. 
       FIG. 11  shows an internal combustion engine  101  in accordance with the invention with a crankcase  102  and a cylinder head  103  in a cross-sectional view normal to the crankshaft axis (not shown). 
     A reciprocating piston  104  is arranged in a cylinder  130 . Cylinder  130  is enclosed by a cooling jacket  105 . Cooling jacket  105  is in connection with an inlet distributor chamber  107  via a connecting duct  106 , which distributor chamber is positioned above a main oil duct  140 . An oil cooler is arranged upstream of the inlet distributor chamber  107  in the coolant circulation between a coolant pump (not shown) and the inlet distributor chamber  107 . 
     Cooling jacket  105  is in connection with cooling chambers  109 ,  110  of the individual cylinder head  103  via transfer openings  108  in the cylinder sealing plane  135 . A bottom cooling chamber  109  is separated from the upper cooling chamber  110  via an intermediate deck  111 . The bottom and upper cooling chamber  109 ,  110  are mutually connected via an annular transfer opening  112  for example between intermediate deck  111  and an injector sleeve  113  for receiving an injector  114 . The ring form of the transfer opening  112  can be interrupted by casting expansions. Other forms of transfer openings  112  are possible. The upper cooling chamber  110  is in connection with the push rod chamber  137  via the transfer opening  131 . The cooling medium exits beneath the outlet duct  120  via the outlet opening  118  from the cylinder head  103  and through a similarly shaped opening in the cylinder head gasket  141  into the crankcase  102 . The cooling medium is guided via the individually bent return ducts  121  into the longitudinally extending return collecting chamber  115 . The return collecting chamber  115  is connected with the intake side of the water side (not shown in closer detail) via coolant lines in which the thermostat valve and cooler are arranged. The inlet distributor chamber  107  and the return collecting chamber  115  are arranged in an integral way with the crankcase  102  and are arranged in the region of a side wall  102   a  of the crankcase  102 . 
     After exiting from a coil of the water pump (not shown in greater detail), the coolant is guided via an intermediate housing to an inflow or distributor chamber  134  before an oil cooler  127  arranged inclined in the crankcase  102 , which oil cooler is arranged on the outside in the region of the side wall  102   a  of the crankcase  102 . Reference numeral  127  indicates the oil cooler. Reference numeral  128  designates the flange for an oil cooler cover. An even flow through the individual oil cooler fins is achieved by the inclined arrangement of the oil cooler  127  and the inclined oil cooler chamber  129 , with flow shadows being prevented to a substantial extent. Since a number of oil-guiding cast slugs  123  of the oil guide means of the oil cooler bypass valve are arranged on the coolant discharge side  133  of the oil cooler chamber  129 , the inlet  132  in the area of the coolant discharge side  133  is curved in an arc-shaped manner towards the rear end of the inlet distributor chamber  107 . 
     After the transversal flow of oil cooler  127 , the coolant is guided into an inlet distributor chamber  107  arranged alongside a side wall  102   a  of the crankcase  102 . The flow is indicated in  FIGS. 11 to 13  by arrows P. From the inlet distributor chamber  107 , the coolant liquid enters a connecting duct  106  which is arranged, in a plan view, radially to the cylinder  103 , namely 90° to the crankshaft axis, and which is arranged at first in a normal plane to the cylinder axis  116  and then faces upwardly inclined in the direction of the cylinder axis  116 . The entrance opening  106   a  of the connecting duct  106  is thus arranged lower than the outlet opening  106   b . As a result of the special shape of said connecting duct  106 , an intense cross-flow cooling can be achieved in the upper hot area of cylinder  130 . As a result of the radial inflow from the connecting duct  106  into the cooling jacket  105 , an even distribution of the coolant on either side of the cylinder  130  is achieved, as is indicated in  FIG. 15  by arrows P. Moreover, the even distribution between the first to the last cylinder  130  can be controlled in a very favorable manner by varying the inlet cross sections to the individual cooling jackets  105 . 
     The control of the cross-flow in the upper hot part of the crankcase  103  occurs by means of differently large transfer cross sections in the region of the (in total four) transfer openings  108  into the cylinder head gasket  141 . The cross section of two transfer openings  108  directly above the connecting duct  106  is smaller than the cross section of two transfer openings against the connecting duct  108 . In order to avoid a dead-water zone, one of these transfers has a larger cross section. The cross sections were adjusted by means of CFD calculations (Computer Fluid Dynamics). The coolant flowing into the bottom cooling chamber  109  cools at first the hot fire deck  117 . The coolant then moves to the upper cooling chamber  110  of the cylinder head  103  around the centrally arranged injector sleeve  113  and through a cooling chamber  110  of the cylinder head  103 . The drilled transfer  136  is used for cooling the valve guide sleeves on the intake side which are not included in the main flow. 
     Together with the position of the four transfer openings  108 , the central arrangement of the annular transfer openings  112  between the intermediate deck  111  and the injector sleeve  113  lead to a highly efficient cooling even between the individual intake and exhaust ports  120  and the valve reinforcing ribs. 
     As a result of the shape of the intermediate deck  111 , which is curved downwardly in the central area  122 , the coolant is deflected in the direction of the fire deck  117  in order to improve cooling in this area. 
     The coolant flows from the upper cooling chamber  110  through a rectangular opening  131  arranged on the outlet side  119  adjacent to the outlet duct  120  into the push rod chamber  137  and leaves the cylinder  103  through a return opening  118  arranged between the sleeves  138  of the push rod transfers  139  in the direction towards the return chamber  115  in the crankcase  102 . 
     In the crankcase  102 , a curved duct portion of the return duct  121  guides the coolant from the connecting opening  118  into the return collecting chamber  115  situated above the inlet distributor chamber  107 . 
     The outlet opening  124  of this return collecting chamber  115  is arranged on a face side  126  of the crankcase  102  like the coolant inlet  125  into the inlet distributor chamber  107 , as is shown in  FIGS. 12 and 13 . The coolant then reaches the thermostat housing arranged above the water pump (not shown in closer detail) via an intermediate housing (not shown in closer detail). 
     The multi-part pulley  201  for a poly-V belt consists of a belt part  202  and a hub part  203 . The belt part  202  comprises belt receiving surfaces  204 ,  205  which are arranged in a stepped manner relative to each other and has different diameters D 1 , D 2  for receiving two poly-V belts (not shown in closer detail). The belt part  202  and the hub part  203  are joined to each other via a pressed or shrink joint, with the hub part  203  being arranged within the belt part  202 . 
     The belt part  202  consists of steel, as a result of which an especially high surface quality can be achieved in the area of the belt receiving surface  204 ,  205 . The hub part  203  consists of a casting material, e.g. cast iron, for cost reasons and due to its complex shape. 
     A vibration damper  206  is fastened to hub part  203  by means of screws  207 . Pulley  201  plus vibration damper  206  is rotationally connected by means of fastening screws  208  to a crankshaft  209 . Reference numeral  215  relates to a crankcase receiving the crankshaft  209 . The bearing surfaces for the fastening screws  208  are designated in  FIG. 20  with reference numeral  208   a . The threaded bores for the screws  207  for fastening the vibration damper  206  to hub part  203  bear the reference numeral  207   a.    
     For better cooling the vibration damper  206 , it comprises breathing elements in the area of its face sides  206   a ,  206   b  which are formed by fan blades  209 ,  210  which can be glued to the vibration damper  206  for example. Furthermore, the hub part  203  can comprise substantially axially cross-flow openings  211  for cooling air in order to improve cooling of the vibration damper  206 . The cooling air flows according to arrows S axially into the pulley  201  and reaches through the cross-flow openings  211  into a gap space  212  between pulley  201  and vibration damper  206 . The cooling air flows along the face surface  206   a  of the vibration damper  206 , support by the fan blades  209 , radially in the gap space  212  to the outside and thereby cools the surface of vibration damper  206 . The fan blades  210  also cool the second face surface  206   b  of the vibration damper  206 . 
     Belt part  202  has a bimetallic corrosion protection. The connection area  213  and the contact area  214  between belt part  202  and hub part  203  is not coated. 
     In comparison with a pulley forged of one part in which a large number of mechanical machining steps would be necessary as a result of the necessary die draughts, the described two-part pulley  201  leads to a substantially lower production effort. 
     The pump  302  which is driven by a crankshaft (not shown in detail) via a driving wheel  201  and which is arranged in the embodiment as a gear pump and belongs to a lubrication circulation  331  comprises a housing  303  with a pump chamber  304  in which conveying wheels  305 ,  306  are arranged which are formed by combing gearwheels. The conveying wheels  305 ,  306  are rotatably held in the housing  303  via shafts  305   a ,  306   a.    
     Pump chamber  304  is connected via the intake side  305  of pump  302  via an intake pipe  307  with an oil collecting chamber  308  formed by an oil pan, from which lubricating oil is sucked in via an intake strainer  309 . The pressure side D of pump  302  is connected via an oil filter  310  and optionally via an oil cooler  311  with an main oil duct  312 . 
     A control valve  313  is integrated in the housing  303  of pump  302 , which control valve comprises a control piston  315  displaceable in a control cylinder  314 . A control line  317  opens into a control chamber  316  formed by the control cylinder  314  and the control piston  315 , which control line originates from the main coil duct  312 . Jacket  314   a  of cylinder  314  is further connected with the pressure duct  318  of pump  302 . A control edge  319  of the control piston  315  controls an opening  302  in jacket  314   a  of control cylinder  314 , which opening is connected with the pressure duct  318 , as a result of which the flow connection to a return line  321  is released which opens into the oil chamber  308 , with the outlet opening  321   a  of said return line being situated beneath the oil level  322 . Since the opening  321  of control valve  313  opens beneath the oil level  322  into the oil chamber  308 , foaming of the returned oil is prevented. The return line  321  originates from a return opening  330  of control valve  313 . 
     The control piston  315  is pressed by a spring  323  in the direction of the control chamber  316 . Once the control pressure p st  in the control line as defined by the pressure in the main oil duct  312  exceeds a value predetermined by spring  323 , the control piston  315  is displaced against the force of spring  323 , through which the opening  320  is released and the pressure lie  318  is relieved. As a result of this control by means of pressure p st  in the main oil duct  312 , only the quantity required by the internal combustion engine is pressed through the oil filter  310  and oil cooler  311 , which enables a very low drive power of pump  302 . Fuel can thus be saved. It is still possible to bring the tenacious oil as quickly as possible to the lubrication points during cold starting. 
     In addition to the control valve  315 , a pump safety valve  324  can be provided which is set to a substantially higher pressure and which can also be integrated in the housing  303  of pump  302 . The pump safety valve  324  comprises a piston  326  which is displaceable in a cylinder  325  which is connected via a control line  327  with the pressure line  318 . The piston  326  of the pump safety valve  324  which is loaded by a spring  328  is thus controlled directly by conveying pressure PD which is applied to the pressure side D of pump  302 , with the pressure at which the piston  326  opens a return opening  329   a  for a return line  329  opening into the oil chamber  308  being defined by spring  328 . 
     Although pump  302  is shown in the embodiment as a gear pump, the type of control can be applied in principle to any known pump  302 .