The present invention relates to a cast engine block for liquid-cooled internal combustion engines with a V-shaped cylinder arrangement in which a crankcase is connected with cooling medium spaces for cylinder blocks delimiting the cylinders by way of base plates connected with the cylinders.
In a known type of construction, the cylinder blocks arranged V-shaped above the crankcase have relatively low interior side walls which are connected with one another in one piece by an essentially horizontal cover wall. This cover wall is connected with a center longitudinal wall extending in the engine longitudinal direction which is erected above the junction point of the two mutually inclined base plates. This center longitudinal wall includes on both sides ribs protruding into the cooling medium spaces of the cylinder blocks which are arranged essentially in planes of bearing block walls arranged in the crankcase. At the end on the cylinder head side the ribs are operatively connected with cylinder head bolt pipes for fastening the cylinder head. Additioally, the center longitudinal wall is provided with apertures for the connection of the cooling medium spaces.
This construction of the engine block is costly as regards casting techniques. Furthermore, the center longitudinal wall produces on both sides relatively large cooling medium spaces in the cylinder blocks with considerable proportions in the area of the V-space. In a V-engine having an air supply installation arranged in the V-space and exhaust gas lines arranged along the outer side, a relatively large amount of cooling medium is then present in the area of the engine block which is cooler owing to the air feed. A further disadvantage of the prior art construction of the engine block resides in that the cooling medium pump supplies the cooling medium directly into the relatively cool and relatively large proportions of the cooling medium spaces located on both sides of the center longitudinal wall and differing thermal stresses are thus possible between the inner and the outer sides of the V-shaped arranged cylinder blocks.
Finally, a part of the spiral housing of the cooling medium pump is integrated into the end wall within the area of a cylinder block in the prior art construction for reducing the length of the engine block. However, there is no indication in the prior art how the cooling medium pump could be advantageously arranged and construction in relation to an chain- or toothed-belt transmission arranged ahead of the end wall for the drive of the control shafts.
The present invention is concerned with the task to construct an engine block of the aforementioned type with a modified cooling medium conduction system which, for avoiding unequal thermal stresses, permits a preferred admission of hot zones of the engine block, which additionally enables smaller cooling medium spaces in the cylinder blocks with a simple construction from a casting point of view of highly stressable inner side walls of the cylinder block and which finally permits by constructively simple measures a cooling medium pump independently accessible from the chain- or toothed-belt transmission in a V-engine with overhead control shafts driven by the envelope gear.
The underlying problems are solved according to the present invention in that channels for the cooling medium inlet to the cooling medium spaces of the cylinder blocks are arranged at the other end of the engine block remote from the cooling medium pump, in that a cooling medium line connecting the channels with the pressure connection can be arranged between inner side walls of the cylinder blocks free of apertures and connected with the base plates, and in that the cooling medium pump having a radial rotor and a housing including a suction-space and a cooling medium line connection is arranged as plug-in type component in the separate part of the spiral housing.
The cooling medium supply to the engine blocks at the ends remote from the pump enables together with a connecting line between the channels and the cooling medium pump which is arranged in the V-space of the engine block, a free layout and design of the cooling medium spaces in the cylinder blocks, whereby the inner side walls of the cylinder blocks can be constructed free of apertures from the cylinder head side connection to the connection with the base plates. Loads from the cylinder head are transmitted by the side walls by way of the base plates into the bearing block walls of the crankcase with a favorable stress distribution. For achieving a small cooling medium jacket about the cylinders the side walls can additionally be moved closely to the cylinders by means of the separately constructible cooling medium spaces of the cylinder block, whereby the side walls for purposes of self-reinforcement without additional ribs are subdivided into arcuately shaped sections coordinated to the cylinders. If the joint places of two arcuately shaped sections of a side wall are located in a plane of a bearing block wall, then an advantageous force transmission into the bearing block walls of the crankcase is achieved without additional reinforcements by means of the bolt pipes arranged at the joint places for the fastening of the cylinder heads. The described measures provide a simple construction advantageous from a casting point of view for the engine block with a high mechanical loading or stressing capacity of the engine block. This is further enhanced by a cooling medium pump adapted to be assembled by means of a plug-in connection, into the housing of which are integrated further parts of the cooling medium supply.
In one embodiment of the present invention, it is proposed for the channels serving for the supply of the cooling medium into the cooling medium spaces of the cylinder blocks that these channels supply the cooling medium unthrottled at their discharge orifices to relatively hot zones whereas the cooling medium is conducted throttled to the relatively cool zones. This measure serves for achieving uniform thermal stresses in the engine block. For the mutual reinforcement of the V-shaped cylinder blocks, the engine block includes at both ends each in the peak of the V-space a flange with an aperture. The apertues may serve for the arrangement of a separate conduction for the supply of the cooling medium from the pump-side end to the end of the engine block on the side of the clutch connection. However, they may also serve as inflow and outflow openings of a channel formed by sections of the inner side walls and of a closure cover connecting the side walls. For avoiding separate channels, the channels which serve for the cooling medium supply to the cooling medium spaces of the cylinder blocks, according to another feature of the present invention, are formed-in in the end wall of the engine block on the side of the clutch connection and are closed off by means of a common cover adapted to be screwed together with the corresponding flange between the cylinder blocks. The throttling devices provided at the discharge orifice leading to the relatively cool areas of the engine block can be constructed in a simple manner which involves means of the channels constructed as recesses by simple measures from a casting point of view. The flange at the pump side end seves for mechanically relieving a relatively thin closure wall of a gear box with separate cover which is provided for the envelope gear. According to a further feature of the present invention, a part of a spiral housing of the cooling medium pump is integrated into the closure wall whereas the other part of the spiral housing is integrated into the end wall within the area of a cylinder block for achieving a short structural length of the engine block. The cooling medium pump can be located in close proximity, for example, with a chain-or toothed-belt transmission constructed as oil-lubricated chain drive by means of a cylinder block that can be constructed relatively narrow owing to a small cooling medium space. In order to make accessible both functional areas independently of one another, on the one hand, and to avoid a direct mutual sealing of lubricating oil and cooling medium, on the other, the gear box includes within the area of the spiral housing a collar suitable for a plug-in arrangement of the cooling medium pump, and additionally a side wall arranged spaced from the collar for the sealing abutment of the gear box cover. Both functional areas are thus separately accessible in an advantageous manner, whereby for purposes of simplified handling of the plug-in type cooling medium pump, the latter is sealed off with respect to the collar by a conventional O-ring. One functional area is thus accessible without any effect on the sealing medium of the other functional area.