Abstract:
A thermal engine for an automotive vehicle, including at least one cylinder block including a first inner circuit for circulating a cooling liquid, of the type in which the first inner circuit includes an outer supply duct including an inlet opening into a reception chamber for a rotor of the engine water pump formed in the block. The chamber includes in its intermediate portion a supply opening having a level located above the level of the inlet opening of the inner supply duct of the first inner circuit. An additional degassing duct connects the upper portion of the reception chamber or water pump volute with an element of the engine cooling circuit.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a heat engine for a motor vehicle. 
     The invention relates more particularly to a heat engine for a motor vehicle, of the type which comprises at least one cylinder block which comprises a first internal circuit for the circulation of a cooling liquid, of the type in which the first internal circuit comprises an internal supply duct an inlet orifice of which opens into a reception chamber or “volute”, that is substantially cylindrical, of a rotor belonging to a water pump of the engine, which is formed in the block, said chamber comprising in an intermediate portion a supply orifice the level of which is arranged above the level of the inlet orifice of the internal supply duct of the first internal circuit. 
     Many examples of heat engines of this type are known. 
     A known disadvantage of this type of engine is associated with the particular arrangement of the orifice for supplying the reception chamber or “volute” of the water pump with respect to the inlet orifice of the first circuit. 
     Specifically, in this configuration, when it is desired to fill the cooling circuit by gravity, an air pocket forms in the upper portion of the reception chamber or volute which is situated above the level of the orifice for supplying said reception chamber. 
     This residual air pocket prevents the priming of the water pump when the engine is started, which may result in damage to the water pump or a lack of the circulation of the cooling liquid within the cooling circuit of the vehicle. 
     It is therefore necessary to fill the cooling circuit under pressure in order to achieve a correct priming of the water pump. 
     SUMMARY OF THE INVENTION 
     To remedy this disadvantage, the invention proposes an engine of the type described above comprising means for draining the upper portion of the reception chamber or volute of the water pump. 
     For this purpose, the invention proposes a heat engine of the type described above, characterized in that it comprises an additional venting duct which connects an upper portion of the reception chamber or volute of the water pump to an element of the cooling circuit of the engine in order to allow the reception chamber to be completely filled by gravity when the first internal circuit is filled. 
     According to other features of the invention:
         the determined element is a chamber which is formed in the cylinder block and which forms part of the first internal circuit,   the additional duct is a calibrated duct formed in the cylinder block,   the cylinder block is capped by a cylinder head, a second internal circuit for the circulation of a cooling liquid communicating with the first internal circuit via at least one drill hole formed in a cylinder head gasket, and the determined element is said drill hole in the cylinder head gasket,   the additional duct is formed in the cylinder block and opens into the drill hole in the cylinder head gasket,   the additional duct is cast in one piece with the cylinder block and is calibrated by the cylinder head gasket,   the additional duct is a calibrated drill hole made in the cylinder block,   the determined element is an external duct for supplying an engine member, notably an oil cooler, with cooling liquid, said external duct being placed beside the block,   the additional duct is formed in the cylinder block and opens into the external duct via a hole.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the invention will appear on reading the following detailed description for the understanding of which reference will be made to the appended drawings in which: 
         FIG. 1  is a schematic view in perspective of an engine block according to a prior art; 
         FIG. 2  is a detailed schematic view in perspective of an engine block according to a first embodiment of the invention; 
         FIG. 3  is a detailed schematic view in perspective of an engine block according to a second embodiment of the invention; 
         FIG. 4  is a schematic view in section of the engine according to the second embodiment of the invention; 
         FIG. 5  is a schematic view in perspective of an engine block according to a third embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, identical reference numbers designate parts that are identical or have similar functions. 
       FIG. 1  depicts a motor vehicle engine  10  comprising a block  11 , commonly called a “cylinder block”, capped by a cylinder head  13 . 
     In a known manner, the cylinder block  11  comprises a first internal circuit  12  for the circulation of a cooling liquid which is designed for example to cool the engine block  11  by allowing circulation of a cooling liquid around the cylinders  15  of the engine. 
     In a known manner, the first internal circuit  12  comprises an internal supply duct  14 , an inlet orifice  16  of which opens into a reception chamber  18 , also called a “volute”, which is arranged in the block  11  and which is designed to receive a rotor (not shown) of a water pump fitted to the engine  10 . 
     In a known manner, the reception chamber  18  is formed in the cylinder block  11  and it comprises, in an intermediate portion  20 , arranged for example substantially level with the axis “A” of rotation of the rotor (not shown), a supply orifice  22  designed to allow the water pump of the engine to be supplied with cooling liquid. 
     As can be seen in  FIG. 1 , in a known manner, the level N 1  of the orifice  22  for supplying the reception chamber  18  is arranged above the level N 2  of the inlet orifice  16  of the internal supply duct  14  of the first internal circuit  12 . 
     A known disadvantage of heat engines  10  made in this design is associated precisely with the difference between the level N 1  of the supply orifice  22  and the level N 2  of the inlet orifice  16  of the first internal circuit  12 . 
     Specifically, when it is desired to fill such a cooling circuit by gravity, because of the difference between the levels N 1  and N 2 , an air pocket forms in the upper portion  24  of the reception chamber  18  which is arranged above the supply orifice  22  of the reception chamber  18 . 
     This residual air pocket prevents the priming of the water pump when the engine is started, which may result in damage to the water pump or a lack of circulation of the cooling liquid within the cooling circuit of the vehicle. 
     It is therefore necessary to fill the cooling circuit under pressure in order to achieve a correct priming of the water pump, and a draining of the circuit at another point, which complicates the operation to fill the circuit. 
     To remedy this disadvantage, the invention proposes an engine  10  of the type described above, comprising means for draining the upper portion  24  of the reception chamber  18  of the water pump. 
     For this purpose, the invention proposes a heat engine  10  of the type described above, characterized in that it comprises an additional venting duct  26  which connects the upper portion  24  of the reception chamber  18  of the water pump to an element of the cooling circuit of the engine in order to allow the reception chamber  18  to be completely filled by gravity when the first internal circuit  12  is filled. 
     According to a first embodiment of the invention, which has been shown in  FIG. 2 , the determined element to which the additional duct  26  is connected is a chamber  28  which is formed in the cylinder block  11  and which forms part of the first internal circuit  12 . This chamber  28  is for example a peripheral chamber surrounding a cylinder  15  of the cylinder block  11 . 
     In this embodiment, the additional duct  26  is preferably a duct  26  formed in the cylinder block  11 , and this duct  26  is calibrated so as to allow a leakage of cooling liquid from the reception chamber  18  of the water pump which is sufficient to allow the air pocket to be dispelled, and which is nevertheless small enough not to hamper the operation of the water pump. 
     According to a second embodiment of the invention which has been shown in the detailed views of  FIG. 3  and of  FIG. 4 , the invention advantageously takes advantage of the presence of a cylinder head  13  of the engine which caps the cylinder block  11 . 
     A cylinder head gasket  32  is arranged between an upper face  34  of the cylinder block  11  and a lower face  36  of the cylinder head  13 . 
     As illustrated in  FIG. 4 , the cylinder head gasket  32  comprises at least one drill hole  38  which allows the first internal circuit  12  of the block  11  to communicate with a second internal circuit  40  of the cylinder head  30 . 
     In this configuration, the determined element to which the additional venting duct  26  is connected is the drill hole  38  in the cylinder head gasket  32 . 
     For example, the additional venting duct  26  is formed in the cylinder block  11  and it opens into the upper face  34  of the block  11  via an orifice  30  which is designed to substantially coincide with the drill hole  38  of the cylinder head gasket  32 . 
     In a manner similar to the preceding embodiment, as illustrated in  FIG. 4 , the additional duct  26  may advantageously be calibrated by the cylinder head gasket  32  itself, the latter being able to obstruct to a greater or lesser degree the end of the additional duct  26  formed by the orifice  30  so as to regulate the flow rate of cooling liquid circulating in said additional duct  26 , in order to allow sufficient venting of the air pocket contained in the reception chamber  18  without however hampering the operation of the water pump. 
     Advantageously, it will be understood that in this embodiment, the additional duct  26  will preferably be cast in one piece with the cylinder block  11 , which makes it possible to achieve its calibration only via the cylinder head gasket  32  without requiring particular machining of said duct  26 . 
     It will also be understood that, as a variant, the additional duct  26  may, in a manner similar to the first embodiment of the invention, be a calibrated duct which opens fully into the drill hole  38  of the cylinder head gasket, the calibration of the additional duct  26  then resulting from a machining of said duct  26 , and notably of its end orifice  30 , in the cylinder block  11 . 
     Finally, according to a third embodiment of the invention which has been shown in  FIG. 5 , the determined element to which the additional venting duct  26  is connected may be an external duct  42  for supplying an engine member, for example an oil cooler  43 , with cooling liquid, said external supply duct  42  being placed beside the cylinder block  11 . 
     In this configuration, at least a communication portion  44  of the external duct  42  comprises a wall independent of the cylinder block and a wall forming part of the cylinder block  11 , which communicates with the additional duct  26  via a hole  50 . This design advantageously makes it possible to dispense with a connection of the additional duct  26  with the communication portion  44  of the external duct  42 , while ensuring a perfect seal. 
     The external duct  42  is then delimited in its communication portion  44  by its independent wall and by its wall formed on the outside of the cylinder block  11 . 
     The invention therefore advantageously makes it possible to achieve venting of the reception chamber  18  of a water pump belonging to a motor vehicle engine  10 , which makes it possible to fill the cooling circuit by gravity without needing to pressurize said cooling circuit. 
     The maintenance of such a motor vehicle engine  10  is therefore made much easier.