EP0466542B1 - Cylinder block for an engine comprising a carter vapour evacuation and oil recycling circuit - Google Patents

Description

The present invention relates to a cylinder block for any internal combustion engine, for example of the V-cylinder or in-line type.

During the operation of an internal combustion engine, there is leakage of combustion gases at the piston segmentation, which results in the presence of unused gas in the crankcase. These gases from the crankcase must be evacuated to avoid any pressure build-up in the crankcase. Furthermore, it is also desirable to recycle the engine oil which is supplied to the cylinder head to the sump, in particular for the lubrication of the valves.

To do this, cylinder blocks have been proposed in which internal conduits are made connecting the upper part of the block facing the cylinder head to lower compartments which separate the crankshaft bearings, in order to allow the evacuation of gases from the casing and the recycling of engine oil.

Thus, document FR-A-2 223 562 describes a cylinder block corresponding to the preamble of claim 1.

However, the internal conduits of the prior art are of complex shape, and have small gas and oil passage sections. In addition, these conduits are obtained by machining or with the aid of foundry spindles or fragile molding cores, so that the cylinder blocks thus produced are expensive and insufficiently rigid.

Also, the object of the present invention is to remedy these drawbacks by proposing a cylinder block with internal ducts for discharging the gases from the crankcase and for recycling the engine oil which are simple in shape and have large passage sections. , and which, in addition, can be produced at a lower cost, while increasing the rigidity of the block, thanks to the use of a unique and resistant molding core.

To this end, the subject of the invention is a cylinder block such as of the V-cylinder or in-line type, and comprising internal conduits which connect the upper part of the block to compartments separating crankshaft bearings, these conduits which allow the evacuation of the gases from the crankcase and the recycling of the engine oil being integrated into a one-piece foundry assembly, this cylinder block being characterized in that said internal evacuation and recycling conduits open into a shaped chamber flattened in a plane substantially perpendicular to the axis of the cylinders and arranged near the lower compartments, said chamber which is crossed perpendicularly by the cylinders, and said internal conduits jointly forming an integrated circuit in said one-piece foundry assembly.

Another advantage of the invention resides in that the circuit includes gas passages from the casing which connect the aforementioned chamber to each of the lower compartments.

Another advantage of the invention resides in that internal oil recycling conduits extend substantially parallel to the cylinders and respectively connect the circuit chamber to a mounting plane of a cylinder head and to a lower face. opposite of the block, these conduits being offset with respect to each other.

It will also be specified here that, for an engine whose cylinders are arranged in two V-shaped lines, the circuit chamber has the shape of a dihedral, with a central or edge part which is connected to conduits internal extending between the two lines of cylinders and opening onto a face of the block provided for mounting a gas treatment member of the casing.

Another advantage of the invention resides in that cooling chambers are formed around the cylinders for the circulation of a cooling liquid, the circuit chamber being located between the cooling chambers and the aforementioned lower compartments.

However, other advantages of the invention will appear better on reading the detailed description which follows and which refers to the appended drawings, given solely by way of example, and in which.

Figure 1 is a perspective view of a cylinder block according to the invention, for an internal combustion engine of the V-cylinder type.

Figure 2 is a sectional view of the cylinder block of Figure 1 and along the line II-II.

FIG. 3 illustrates in perspective the shape of the chamber and of the internal conduits which constitute the evacuation and recycling circuit according to the invention.

Referring first to FIG. 2, it can be seen that an engine M comprises in particular a cylinder block 1, a lower casing 2 and two cylinder heads 3a and 3b which are fixed to the cylinder block 1.

Following the example illustrated in FIGS. 1 and 2, the engine M is of the type with 6 cylinders in V, that is to say comprises, on either side of a longitudinal plane XX 'two lines of three cylinders 41 and 42. It is also noted that lower compartments 5 which separate transverse walls 11 (only one of which is visible in FIG. 1 and on FIG. 2) in which crankshaft bearings 12 are formed are produced in the cylinder block 1 so as to open into a face forming a lower joint plane 13 against which the lower casing 2 is mounted.

Each cylinder 41, 42 opens on the one hand into the upper part 143 of the block 1 and on the other hand into one of the lower compartments 5. The three aligned cylinders which are designated by the reference numeral 41 are produced on one side from the longitudinal plane XX 'and open onto a joint plane 141 of the upper part 143, on which plane the cylinder head 3a is mounted. The other three cylinders 42 are produced in the block 1 on the other side of the plane XX ′ and lead to another joint plane 142 of the upper part 143, on which plane the cylinder head 3b is mounted.

It should be noted here that a jacket can be inserted into each cylinder 41, 42, for example during the molding of the cylinder block 1.

There have been identified in 151, 152, two coolant supply conduits, produced in block 1 and which extend substantially parallel to a longitudinal direction of block 1. The supply conduits 151 and 152 are respectively connected to cooling chambers 161 and 162 which are formed around each cylinder 41, 42, so as to allow circulation of coolant in the block 1.

Holes 171, 172 for communication of the cooling chambers 161 and 162 with the cylinder heads 3a and 3b open respectively in the joint planes 141 and 142. The coolant is introduced into the block 1 via an opening 153 which opens into a transverse face 6 of the block 1 and which extends substantially parallel to the transverse walls described above.

FIG. 2 shows a longitudinal channel 173 for circulation of pressurized oil which extends in the longitudinal direction of the casing 2, along the lower compartments 5.

The cylinder block 1 also comprises internal conduits for discharging gas from the crankcase and for recycling the oil which will now be described, with further reference to FIG. 3.

According to the invention, the cylinder block 1 comprises internal pipes 7 for recycling engine oil and internal pipes 8 for evacuating the gases from the crankcase which open into a chamber 9, so as to form a circuit C foundry with block 1 and shown in perspective in Figure 3.

The chamber 9 of the circuit C is in the form of a flattened dihedron and extends near a top wall 51 of the lower compartments 5 of the block 1. The chamber 9 is therefore constituted by two flattened and contiguous parts identified at 91 and 92 Each flattened part 91 and 92 of the chamber 9 is crossed substantially at right angles by the cylinders 41 and 42, respectively. A central part 93 of the chamber 9 forms an edge which extends in the longitudinal direction of the block 1, right through the chamber 9.

Two evacuation conduits 8 of oblong section extend, between the cylinders 41, 42, from the upper part of the edge 93 to a central face 144 of the block 1 which is provided for mounting a member for treatment (not shown) of the crankcase gases.

It is therefore understood that the chamber 9 of the circuit C formed in the cylinder block 1, is located between the cooling chambers 161 and 162 and the lower compartments 5.

The recycling conduits 7 extend laterally from each free end of the flattened parts 91, 92 of the chamber 9, and consist of upper sections 7a and lower sections 7b.

According to the example illustrated, each flattened part 91, 92 of the chamber 9 comprises five upper sections 7a and three lower sections 7b, of oblong section. The upper sections 7a of the recycling conduits 7 are formed in the block 1 so as to extend substantially parallel to the cylinder lines 41 and 42. These upper sections 7a are connected five to five, at their upper part, by channels 71 and 72 which open respectively in the joint planes 141 and 142. In FIGS. 1 and 2 it can be seen that each of the channels 71 and 72 is produced near a lateral flange 241, 242 of the joint planes 141 and 142 of block 1, and extend in a direction substantially parallel to the longitudinal direction of the housing.

The lower sections 7b of the recycling conduits 7 extend, from top to bottom along the side walls 52 of the compartments 5 which are parallel to the plane XX ', from one of the flattened parts 91, 92 of the chamber 9 to the joint plane 13 against which the lower casing 2 is mounted.

It is already understood that the descent of the engine oil from the cylinder heads 3a, 3b is improved by the oblong section of the sections 7a, 7b and that, in addition, any emulsion of the oil is avoided since it is recycled at the level crankshaft bearings 12.

It can be seen in the figures that the upper sections 7a and the lower sections 7b of the recycling conduits 7 are offset from one another. In other words, the lower sections 7b are substantially parallel to the plane XX ′ and therefore do not extend exactly in alignment with the upper sections 7a which are parallel to the cylinders 41, 42.

On the other hand, as can be seen in FIG. 3, the lower sections 7b open into the chamber 9 at locations which are not located exactly opposite the ends of the upper sections 7a which open into each flattened part 91, 92 of the chamber 9. Such a shift between the sections 7a and 7b makes it possible to "break" the flow of oil flow towards the lower casing 2, but also makes it possible to improve the evacuation of the gases by allowing the trapped gases in the oil of the lower casing 2 to escape through the lower sections 7b.

Near a lower part of the edge 93 of the chamber 9 are formed passages 94 which pass through the wall 51 to open into each compartment 5, so as to allow optimal evacuation of the gases from the casing using the conduits 8, and for example to a device for treating these gases. It is possible thanks to such passages 94 to connect the various compartments 5 for mounting the crankshaft, in order to improve the operation of the engine.

Thanks to the arrangement of pipes, chambers and passages of circuit C described above, the evacuation of gases from the casing is improved significantly, so that the engine M equipped with a circuit C offers less resistance to the movement of the moving parts such as pistons, connecting rods, etc.

There was therefore obtained according to the invention a cylinder block of inexpensive embodiment, in which it is easy to produce conduits for evacuating gases and recycling oil by interposing a one-piece molding core of similar shape to the circuit visible in Figure 3 in the block casting mold. Such a one-piece core is placed during the preparation of the mold between the cores making it possible to obtain the cooling chambers and the cores defining the crankshaft mounting compartments.

In addition, the cylinder block according to the invention has the advantage of being more rigid thanks to the different separation walls of the chambers and the conduits, which also has the result of improving the sound absorption of the cylinder block.

It goes without saying that the circuit C described above and provided for an engine M of the V-cylinder type, can also be adapted to an engine of the in-line cylinder type, and that the number of conduits as well as the section of those -these can be adapted to the desired engine operating characteristics.

Claims (5)

1. Cylinder block for any internal combustion engine whatsoever, for example of the type with cylinders in V-arrangement or in line and comprising internal ducts (7,8) which connect the upper portion (143) of the cylinder block (1) to lower compartments (5) separating bearings (12) of the crankshaft, these ducts (7,8) which allow the discharge of the gases from the crank-case and the recycling of the oil of the engine being integrated into a unit cast in one piece, characterized in that the said internal discharge ducts (8) and recycling ducts (7, 7a, 7b) are opening into a chamber (9) of a shape flattened in a plane substantially perpendicular to the axis of the cylinders and disposed in proximity to the lower compartments (5), the said chamber (9) through which the cylinders (41,42) are extending perpendicularly and the said internal ducts (7, 7a, 7b, 8) jointly forming a circuit (C) integrated into the said unit cast in one piece.
2. Cylinder block according to claim 1, characterized in that the circuit (C) comprises passageways (94) for the gas of the crankcase which connects the aforesaid chamber (9) to each one of the lower compartments (5).
3. Cylinder block according to claim 1 or 2, charaterized in that internal oil recycling ducts (7, 7a) extend in substantially parallel relation to the cylinders (41, 42) and respectively connect the chamber (9) of the circuit (C) to a joint plane (141, 142) for the mounting of a cylinder head (3a, 3b) and to an opposite lower face (13) of the cylinder block (1), these ducts being offset with respect to each other.
4. Cylinder block according to one of claims 1 to 3, characterized in that with an engine (M) the cylinders (41, 42) of which are disposed along two lines in V-arrangement, the chamber (9) of the circuit has the shape of a dihedron (91, 92) with a central portion or ridge (93) which is connected to internal ducts (8) extending between both lines of cylinders (41, 42) and opening on one face (144) of the crankcase (1) provided for the mounting of a member for the treatment of the gases of the crankcase.
5. Cylinder block according to one of claims 1 to 4, characterized in that cooling chambers (161, 162) are formed about cylinders (41, 42) for the circulation of a cooling liquid, the chamber (9) of the circuit being located between the cooling chambers (161, 162) and the aforesaid lower compartments (5).

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