FR2790285A1 - Liner for cylinder of internal combustion engine has stop shoulder on liner which deforms under axial preload to position liner in cylinder block - Google Patents

Abstract

The liner for the cylinder of an internal combustion engine has a stop shoulder (6) formed radially on its outer surface to engage stop abutments formed in the cylinder block bores. The shoulder has a contact face (8) to engage the abutments and hold the liner in position under an axial preload. The rigidity of the contact face and-or the support face (16) of the abutment can be of reduced rigidity to conform under load.

Description

The invention starts from an internal combustion engine

  dull comprising at least one jacket mounted in a cylinder block (s), the jacket having a radially outer shoulder having a bearing face by which it is pressed, with axial prestress, against a support face of a support element

  radially inside the cylinder block (s).

  From the state of the art, internal combustion engines are known in the cylinders of the cylinder block of which liners are mounted. For this purpose, jackets immersed in cooling water are produced (“wet” jackets) and provided at their upper end or in their central region with a radially outer shoulder, but such a shoulder can also be provided on shirts that do not bathe directly in the cooling water ("dry" shirts). The shoulder of the known liners has a planar bearing face directed towards the cylinder block and perpendicular to the axial direction. When mounting the liners in the cylinders of the cylinder block, this bearing face is brought into abutment against a plane abutment face of a

  support element provided for this purpose in the block

  cylinders. A cylinder head is fixed to the cylinder block by studs or head screws and maintains the liners in the cylinders by tightening the bearing face of each of them axially with pretension against the support face of the support element coordinated with the cylinder block. However, during the manufacture of the liners and the cylinder block, machining tolerances cause defects in flatness, staging and

  of the support face and the support face.

  Due to their tightness against each other, there occurs, in the area of the separation joint between the support face and the support face, an irregular distribution of the stress in the circumferential direction, with spikes of local constraints. It follows that the wall of the jacket is deformed, in particular in the radial direction, and a radial camber is also measurable in level planes, in the axial direction, which are further from the shoulder. The unwanted buckling of the jacket results in increased friction power and irregular abrasion of the jacket and of the piston guided by it, as well as of the segments. Warping can further reduce the sealing and scraping effect of the segments, so that, on the one hand, compressed mixture can pass through the segments and, on the other hand, oil can penetrate into the combustion chamber by bypassing the piston. As a result, the engine power decreases and the oil consumption increases. Based on this situation, the invention aims to create an internal combustion engine, of the type mentioned at the start, in which the warping of the

  shirts be avoided to a large extent.

  According to the invention, this re-

  result by the fact that the conformational rigidity of the support face and / or of the support face is more

  lower than that of the zones which are connected to it.

  The internal combustion engine according to the invention

  In particular, the advantage is that due to the targeted increase in flexibility in the area of the support face and the support face, the stress peaks due to inaccuracies in manufacturing are reduced mainly in the radially outer region of the separation joint, and the resulting irregular deformations mainly occur at this location. On the other hand, no notable buckling occurs in the more rigid radially interior zones of the liners, whose dimensional stability is essential for a

  low friction running and little engine wear.

  Such a low warp jacket reduces friction losses in the cylinders and thus guarantees a longer service life and a lower

  engine fuel consumption.

  Other arrangements according to the invention,

  written in what follows, allow development

  advantageous engine improvements and improvements

according to the invention.

  A particularly preferred development of the invention provides that the support face is oriented at an angle relative to the support face, and that these two faces are in particular arranged at an angle to each other in a plane containing the axis of the jacket, and are in contact with each other only in a radially inner zone or, conversely, in a radially outer zone. Due to the angular orientation, a smaller contact surface is obtained on the one hand, which leads, for the same prestressing, to a higher specific surface pressure in the region of the separation joint and consequently also to greater flexibility there. On the other hand, the chamfering offset the contact surface between the bearing face and the support face radially inwards, which is why the lever arm between the radially outer shoulder and the axial forces attacking the end. shirt head becomes shorter. This shortened lever arm in turn decreases the bending torque exerted on the shirt,

  with the result that its tendency to bulge decreases.

  The angular chamfering of the support face and / or of the support face can be carried out, in a simple manner, with symmetry of revolution, so that the

  costs of this operation are low.

  According to another embodiment of the invention, an intermediate layer is disposed between the shoulder and its support element, layer which comprises at least one ring which, under the effect of the prestressing, is elastically deformable and / or in the plastic domain, so that the deformations caused by prestressing mainly occur in the ring. Starting from such an embodiment, the intermediate layer is provided, according to a development, for several

  cylinders arranged in a row and is made of more

  several rings connected to one another in a row and elastically deformable and / or in the plastic field. The elastic intermediate layer is thus produced in the manner of a cylinder head gasket and can be placed simply in the cylinder block, for example in the form of a single piece, which

  allows an easy and inexpensive installation.

  Another embodiment of the invention provides that the support face and / or the support face is profiled in the axial direction, preferably in corrugated form. The pairing of faces generated by the ripple can then be calculated so that the

  deformation of the shirt to be reduced to a minimum.

  Other characteristics and advantages of the invention will emerge more clearly from the

  description which follows of several examples of

  non-limiting embodiment, as well as the accompanying drawings, in which: Figure 1 is a perspective view in section of a cylinder block and a jacket, with provision for an intermediate layer produced as a row of rings attached to each other between the liners and the cylinder block, a layer which is deformable by elastic / plastic deformation; - Figure 2 is a cross section of a ring according to Figure 1; - Figure 3 is a cross section of a ring according to Figure 1 according to another embodiment; - Figure 4 is a perspective view of a shirt provided with a shoulder having an oblique bearing face; - Figure 5 shows on a larger scale a partial section in the area of detail Y of Figure 4, representing in addition, unlike this detail, a part of the cylinder block;

  - Figure 6 is a schematic representation

  tick of a simulation, by the finite element method (MEF) of the configuration of a shirt in the assembled state; - Figure 6a is a greatly exaggerated representation of the deformation of a jacket whose bearing face is perpendicular to the axial direction; - Figure 6b is a greatly exaggerated representation of the deformation of a shirt whose bearing face is bevelled at an angle a = 0.4 degrees; - Figure 6c is a greatly exaggerated representation of the deformation of a jacket whose bearing face is bevelled at an angle a = 0.5 degrees; - Figure 6d is a greatly exaggerated representation of the deformation of a shirt whose bearing face is bevelled at an angle a = 0.6 degrees; - Figure 7 shows another embodiment of the invention, according to which the support face of the jacket is profiled in the axial direction; - Figure 8 shows another embodiment of the invention, according to which an intermediate layer in the form of a ring is profiled in the axial direction; - Figure 9 shows yet another embodiment of the invention, according to which the support face of the jacket is profiled in the axial direction and is further obliquely oriented; and - Figure 10 is a partial section to more

  large scale taken in the detail area Y of the fi-

  gure 9, but showing in addition, unlike this

  detail, part of the cylinder block.

  Figure 1 shows a wet jacket 1

  shortly before mounting in cylinder 2 of a block

  cylinders 4 of an internal combustion engine. For its axial fixing in the cylinder 2, the jacket 1 is provided with a shoulder 6 located radially outside and having an annular bearing face 8 directed towards the cylinder block 4. The bearing face 8 is located preferably in a plane perpendicular to the axis of the jacket 1 and, seen in the direction of the length of the shirt, essentially in the middle, the height of the shoulder preferably corresponding to about 0.5 to 1.5 times the bore of the shirt 1. Shirts having such a shoulder 6 in the middle are also called "shirts with center stop". The median shoulder 6 separates an upper part 10 of larger diameter from a lower part 12 of smaller diameter of the jacket 1. This type of shirt is known in itself. The cylinders 2 of the cylinder block 4 are each provided with a support element 14, which has a flat support face 16, in the form of a ring. During assembly, the lower part 12 more

  small diameter of the shirt is slid into the cy-

  lindre 2, until the bearing face 8 rests on the support face 16. Then, a cylinder head, not shown, is placed on the cylinder blocks 4, to which it is connected in a known manner by studs or screws headed. The liners 1 are thus held in the cylinders 2 by the pressure exerted on their head end by the cylinder head and the bearing face 8 of each liner 1 is pressed with axial prestress against the corresponding support face 16 of the

cylinder block 4.

  According to a preferred embodiment of the in-

  vention, the area of the separation seal between the support face 8 and the support face 16 is more flexible than the areas adjacent to this seal area of the jacket 1 and the cylinder block 4, thanks to the interposition between said two faces 8 and 16 of an intermediate layer 18 elastically deformable and / or in the plastic field and having the form of several rings 20 attached to each other in a row. Such a ring 20 preferably has a lower rigidity of its constituent material than the jacket 1 and the cylinder block 4. Alternatively or additionally, the form stiffness of such a ring can also be low. The result is that the deformations caused by the axial prestress occur mainly in the rings 20, which deform elastically and / or in the area

  plastic. Compared to these deformations of the an-

  neaux, the axial and radial deformations of the che-

  setting 1 more rigid are significantly lower, so that it practically does not deform under the action of axial prestress. So that the

  flexible material of the rings 20 - axially loaded -

  can escape in the radial direction, zones of radial creep may be provided in the region of

  the shoulder 6 and the support element 14.

  Figure 2 shows a cross section taken along line II-II of Figure 1 of a ring a according to a preferred embodiment. This ring is made in one piece and its constituent material has a lower rigidity than the

  jacket material 1 or cylinder block 4.

  The ring 20a has an annular lip 22 disposed radially in the middle and preferably directed towards the bearing face 8 of the jacket 1. The lip 22 is formed directly on the ring 20a, the other side of which has an annular groove 24 , so that the protruding material of the annular lip 22 can be forced back

  under axial stress in the annular groove 24.

  The lip 22, in combination with the groove 24 complementary to it, makes it possible to obtain a particularly great flexibility of the intermediate layer 18, flexibility which is furthermore restricted to an area

tightly limited.

  It is also possible, as a variant, to use a ring 20b like that shown in section in FIG. 3 and which is produced in two parts, constituting respectively a support ring 26 and a deformation ring 28 carried by it and which is flexible. The support ring 26 preferably has an L-shaped profile, an axial branch 30 of which is disposed adjacent to the wall of the jacket 1 and a radial branch 32 extends radially outwards. The deformation ring 28 is housed in the half-groove formed by the axial 30 and radial 32 branches and protrudes in the axial direction of the first. The material of the deformation ring 32 deforms, preferably in the plastic field, under

  the effect of prestressing and can escape radial-

  outward. The axial branch 30 then acts as a stop for the support face 8 or the support face 16 and can deform elastically. Instead of the flexible intermediate layer 18 being provided separately from the jacket 1, it could also be connected to the support face 8, or the support face 16, by force, by their respective shapes or by their

constituent materials.

  FIG. 4 represents another embodiment of the invention, according to which the bearing face 8 of the shoulder 6 of the jacket 1 is slightly bevelled. From Figure 5, which is a longitudinal section in the area of detail Y of the

  figure 4 and shows in addition, unlike this one

  ci, the support element 14 of the cylinder block 4, the support face 16 is planar and parallel to a plane perpendicular to the axis of the cylinder 2. On the other hand, the support face 8 is oriented obliquely and forms a angle a with the support face 16, with which, for this reason, it is only in contact in a radially inner zone. Conversely, the bearing face 8 could also be planar and parallel to a plane perpendicular to the axis of the jacket 1, and the support face 16 could be inclined at an angle a with respect to it. In addition, both the support face 8 and the support face 16 could each be arranged at an angle a with respect to a plane perpendicular to the axis of the jacket 1. Due to the inclined orientation of the support face 8 and / or support face 16, a smaller contact surface is obtained between the shoulder 6 and the support element 14, which leads, for the same preload, to greater pressure surface specificity (pre-stressing force / contact surface) and hence higher flexibility - which is desired - in the area of the separation joint. The bevelling or chamfering of the bearing face 8 is achievable by machining with chip removal, so that it is preferable to provide a clearance 34 for the tool in the shoulder 6. According to another development of the invention, a ring 20 of an intermediate layer 18 according to FIG. 1 could also be provided with a

such inclination.

  FIG. 6 schematically represents a simulation, by the finite element method (MEF), of the configuration of a jacket 1 in the assembled state, the representation corresponding to a longitudinal section of the wall of the jacket. The axial prestressing by the cylinder head, applied against the head end of the jacket 1, is simulated by a static surface load p, acting on the annular head surface of the jacket 1, and the support element 14 is simulated by a support 36. Under the axial load p, the relatively thin wall of the jacket tends to swell, which is further accentuated by the fact that a lever arm acts between the lines of action of the radially inner fractions of the load p and the support element (support 36) radially outside, so that an additional stress of

  deflection is superimposed on the veil stress-

  ment acting on the wall of the jacket 1. This buckling and deflection load generates bending waves in the wall of the jacket, which is visible in the representation of deformation, greatly exaggerated in FIG. 6a for reasons

  of scale and produced by an MEF calculation sequence.

  The bearing face 8 of the shoulder 6 of the MEF calculation model according to FIG. 6a is in fact plane and parallel to a plane perpendicular to the axis of the jacket 1 (x = 0 degrees), so that this one this corresponds to a shirt according to the state of the art. As a result of the calculation in the context of the MEF calculation sequence, a maximum radial buckling of the jacket 1 was found from 16 pm to

  the height of the bearing face of the shoulder.

  To allow comparison, FIG. 6b is a representation of deformation of a MEF calculation model according to which the bearing face 8 is inclined at an angle a = 0.4 degrees relative to a plane perpendicular to the axis of the liner 1. As can be seen, the radial buckling of the liner is much lower in this case. The maximum buckling calculated in the area of the bearing face of the shoulder 6 is only 7 μm. The deformation representations shown in FIGS. 6c and 6d are based on MEF calculation models according to which the bearing face 8 is chamfered respectively at an angle a = 0.5 degrees (FIG. 6c) and at an angle

  a = 0.6 degree (Figure 6d). In the case of a change

  braking of 0.5 degrees, a maximum radial deflection of 6 pm was calculated and, in the case of a chamfer of 0.6 degrees, a maximum radial deflection of

5 pm.

  As explained in the foregoing, the reduction in the radial buckling of the jacket 1 as the inclination of the bearing face of the shoulder increases is to be attributed on the one hand to the lower form rigidity of the jacket in the separation joint area. The chamfering of the bearing face 8 on the other hand causes a radially inward shift of the contact zone between the shoulder and its support, which results in a shorter lever arm for the radially inner fraction. of the axial load attacking the head end of the liner. As a result, the bending moment exerted on the jacket 1 and consequently also its radial warping become weaker. The angle of inclination a is preferably within an angular range between 0.4 and 0.6 degrees. With another dimensioning of the jacket, the angle a could also be understood

  in a range between 0.2 and 1.5 degrees.

  FIG. 7 shows a jacket 1, the bearing face 8 of which is profiled in the axial direction and preferably produced with a wavy shape, the profiling being shown in a highly exaggerated manner. The corrugated profile is located opposite the support face 16, not shown, and is pressed against it during assembly of the jacket. Due to the smaller contact surface in line with the "wave vertices", the profiling produces a higher specific surface pressure (prestressing force / contact surface), which causes the targeted reduction in form stiffness of shoulder 8 in the area of the separation joint. Therefore, the deformations under the effect of prestressing mainly occur in the corrugated support face 8. In addition or alternatively, the support face 16 could also be profiled.

  in a wavy conformation or otherwise.

  As an additional variant, an intermediate layer 18 in the form of a ring 20c can also be provided with such profiling, as shown in FIG. 8. In such a case, a first annular face 38, which can be brought into contact with the bearing face 8 is flat, while the second annular face 40, which can be brought into contact with the support face 16, is produced with a wavy shape; he is

  however, it is also possible to choose the layout

  pour or give a wavy shape to both sides

annulars 38 and 40.

  According to the additional embodiment shown in Figure 9, the support face 8 has a corrugated profiling and is further radially chamfered, as shown in Figure 10 by the partial section taken in the area of detail Y of the figure 9. We see in this section that the support face 8 and the support face 16 enclose an angle between them, owing to the fact that the support face 8 is oriented at an angle a with respect to a plane perpendicular to the axis of the jacket 1 and is only in contact with the support face 16 in a radially inner zone. The support face 16 could be

profiled and chamfered in addition.

  To summarize, the invention provides an increase in the flexibility of the region of the separation joint between the support face 8 and the support face 16 due to the fact that the rigidity of shape and / or the rigidity of the material constituting the face support 8 and / or the support face 16 is or are reduced (s) by the arrangements which have just been described, or by the provision of a flexible intermediate layer 18

between these two faces.

Claims (5)

  1. Internal combustion engine comprising at least one liner (1) mounted in a cylinder block (s) (4), the liner having a radially outer shoulder (6) having a bearing face (8) by which it is pressed, with axial prestress, against a support face (16) of a support element (14) radially inside the cylinder block (s) (4), characterized in that the rigidity of conformation of the support face (8) and / or the support face (16)   is weaker than that of the zones which connect to it.   2. Internal combustion engine according to claim 1, characterized in that the support face (16) and / or the support face (8) is or are profiled in the axial direction and have preferably a wavy shape.   3. Internal combustion engine according to claim 1 or 2, characterized in that the bearing face (8) and the support face (16) are arranged at an angle to one another in a plane containing the axis of the shirt (1).   4. Internal combustion engine according to claim 3, characterized in that the bearing face (8) and the support face (16) are in contact between   they only in a radially inner area.   5. Internal combustion engine according to claim 3 or 4, characterized in that the angle (a) between the bearing face (8) and the support face (16) is preferably within an angular range between 0.4 and 0.6 degree.