FR2711186A1 - Internal combustion engine with cushioned skirts and large bowl. - Google Patents

Abstract

The internal combustion engine comprises a cylinder head (1), an elongated cylinder block (2), crankshaft bearings (3) below the cylinder block, and an oil pan (8). The cylinder block is extended downwards by two hanging side skirts (4) which do not come into direct contact with the crankshaft bearings. The crankshaft bearings have bearing caps (3b) which are mechanically connected to each other by two parallel stiffening bars (6). The oil sump (8) is in the form of a large bowl fixed, uncoupled, on two side flanges (2c) along the cylinder block above the hanging skirts.

Description

l Internal combustion engine with cushioned skirts and large bowl

  The present invention relates to an internal combustion engine

  not intended in particular to equip road vehicles, as well

  tomobiles than trucks. Currently, for the sake of preserving the environment and increasing user comfort, vehicle manufacturers are increasingly looking to use such low-emission engines

  as possible for the environment. Research is essential-

  on the reduction of harmful exhaust gas emissions (mo-

  clean emitters) and the reduction of noise emission levels (

silent guardians).

  To reduce the noise level of the engines, a

  a number of technical solutions have been proposed by the reduc-

  tion of vibrations transferred from the engine pistons to

  motor housing. One solution is to stiffen the city bearings -

  engine crankshaft by mechanically connecting the crankshaft bearing caps to each other. Another solution is to increase the

  surface covered by the oil pan according to the principle of "bowl in-

  "by decoupling the oil sump from the cylinder block to reduce

  alter its coefficient of sound radiation.

  Also known from European Patent No. 0 435 847

  (AVL) an internal combustion engine which has an external structure

  rigid upper laterally surrounding the cylinder block and the crankshaft bearings. The upper part of the external structure is fixed to the cylinder head of the engine. The lower part of the external structure is stiffened by a frame in the form of a ladder placed horizontally in

  below the crankshaft bearings. An oil pan in the form of cu-

  vette is fixed on lateral flanges of the external structure. This Do-

  cument provides a seal between the cylinder head, the cylinder block and the external structure in order to decouple them acoustically for high frequencies and to reduce the level of vibration of the external structure. The oil pan attached to the exterior structure allows

  further reduce the sound radiation of the entire engine.

  This design of the motor aims to dissipate the vibrational energy

  re of the rigid internal structure by an added external structure

  and rigidified in order to act on all vibra-

  roof to the outside. However, the vibrational energy of the parts is much higher.

  due to the acoustic energy radiated by these parts due to their vibrations

  tions. From this point of view, the engine structure described in the docu-

  AVL mentioned above is not an optimal and effective solution for

  reduce the noise level of the engine.

  The object of the present invention is to provide an engine structure with improved vibroacoustic performance, that is to say with a significant reduction in noise emission levels.

outwards.

  The object of the invention is also to simplify the structure of the engine necessary for the reduction of noise emissions by favoring particular paths of propagation of the vibrations to effect

effective damping.

  Another object of the invention is to provide an engine with a rigid internal structure for withstanding forces, and a structure

  external integrating the oil bowl function which is decoupled

  canonically of the internal structure, so as to offer an effective treatment

  effective both acoustically and mechanically,

engine brations.

  The internal combustion engine includes a cylinder head mounted above an elongated cylinder block, and crankshaft bearings mounted below and along the cylinder block. According to the invention, the cylinder block has two side hanging skirts which extend down the lateral sides of the cylinder block. The hanging skirts deviate slightly going down so as not to enter

  direct mechanical contact with the crankshaft bearings. Each pa-

  crankshaft link has a removable bearing cap relative to the bearing base. The bearing caps are connected together by two parallel stiffening bars to make all the crankshaft bearings rigid. An oil pan in the form of a large bowl is suspended in suspension on two longitudinal side flanges

  of the cylinder block located above the hanging skirts.

  In this way, the vibrations of the cylinder block propagate along a privileged path formed by the two hanging skirts which radiate through their lower free end. It is then possible to dampen the vibrations of the lower ends of the hanging skirts by an appropriate damping means. A simple solution consists in connecting, using damping elements, the lower end of the hanging skirts to the crankshaft bearings which are reinforced by the

stiffening bars.

  The damping elements can be constituted by viscous dampers, preferably non-linear, to allow a

  better damping efficiency without significantly increasing

  bearing the stiffness of the shock absorber in operation. Such amor-

  weavers work dynamically to dampen the vibrations of the

  pes hanging. Experience shows that the result of depreciation

  is satisfactory with a film of oil at rest having a thickness less than

  greater than or equal to 50 times the amplitude of the lateral displacements of the lower end of the pendant skirts due to vibrations. We can

  thus effectively mechanically dampen the vibrations of the mo-

tor.

  The large bowl which is mounted decoupled from the structure ri-

  engine gide is preferably flexible to allow good

  damping of engine vibrations. This bowl is preferably

  this made of composite materials and constitutes an acoustic screen

  for noise from outside the engine.

  Thanks to the invention, the level of noise emissions from the engine can be reduced significantly by mechanical treatment of the

  vibrations by means of pendant skirts and dynamic shock absorbers

  ques, and also of an acoustic treatment by the large bowl of oil

  flexible, decoupled from the rigid structure of the motor.

  The efficiency of the mechanical treatment can be further increased.

  than vibrations by creating internal pockets in the skirts

  dantes. In these internal pockets, a granular material is introduced

  which by dry friction between the grains allows a damping of the vi-

  brations. Thus, the vibrations are first damped in the rigid structure at the level of the hanging skirts before being damped for a second

  times by the dynamic shock absorbers at the ends of the hanging skirts

  your. It is also possible, in certain cases, to delete the elements

  depreciation and keep only the depreciation by inclusion

  of granular material in dangling skirts, if such cushioning

  sufficient for the use of the engine.

  According to a variant of the invention, the skirts hanging under

  form of plates can be replaced by a succession of

  very hanging. These hanging beams preferably have ca-

  different characteristics from each other (length, section), so

  to build as many tuned dynamic absorbers. The hanging beams should then be sufficiently damped to cover the entire frequency spectrum (vibrations) to be treated with a reasonable number

  beams. This amortization can be provided by as much amortization.

  dynamic sors than hanging beams mounted at the straight ends

  of these beams, and / or by the introduction of granular materials

  in the internal pockets of the hanging beams. The use of amor-

  Separate weavers associated individually with each hanging beam has the additional advantage of greatly reducing the acoustic radiation coefficient of the hanging skirts, thereby reducing the

  noise transfer by air.

  According to another variant of the invention, perforated openwork skirts can be produced so as to reduce the rigid surfaces for transferring vibrations and consequently reduce the coefficient of

  acoustic radiation from dangling skirts.

  The invention will be better understood on studying a few embodiments taken by way of nonlimiting examples and illustrated by appended drawings, in which:

  Figure 1 is a schematic perspective view of a mo-

  internal combustion tor with the hanging skirt according to a first embodiment of the invention, FIG. 2 is a schematic view in cross section of the engine according to FIG. 1,

  FIG. 3 is a perspective view of the engine according to a section

  cond embodiment of the invention, and Figure 4 is a schematic perspective view of the engine

  according to a third embodiment of the invention.

  To simplify the representation, the engine oil pan

  is not illustrated in Figures 1, 3 and 4. Internal combustion engines

  are well known to those skilled in the art (see for example the patent

  European vet no. 435 847 cited above) and will not be described in detail.

  Subsequently, we will only describe the structure of the direct motor -

  ment concerned by the present invention.

  As illustrated in Figures 1 and 2, the internal combustion engine comprises a cylinder head 1 mounted above a cylinder block

  elongated 2. The cylinder block comprises several cylinders 2a in the

  which slide pistons not shown. The cylinder block 2 pre-

  has interior channels 2b through which a coolant circulates

  cooling of the cylinder block. Below the cylinder block 2 is

  wind several crankshaft bearings 3 aligned along the cylinder block

  2. Each bearing 3 is in the form of a vertical plate in two parts

  ties: a base 3a secured to the cylinder block 2 and a cap 3b

  removably mounted on the base 3a. A crankshaft not shown

  felt is supported by the crankshaft bearings 3 and driven by the

  pistons not shown of the engine in order to activate a gearbox

  unrepresented size of the vehicle.

  The lateral sides of cylinder block 2 are extended towards the

  bottom by two hanging skirts 4 in the form of a plate. Skirts

  dantes 4 are integral with the cylinder block 2 and slightly apart

  to the side so as not to come into direct contact with the

  crankshaft liers 3. Dangling skirts 4 may have po-

  internal chambers 4a into which a granular material 5 is introduced

  (pumice stone, sand, etc.), the usefulness of which will be described later.

  Two stiffening bars 6 parallel and longitudinal are mounted on the bearing caps 3b of the crankshaft 3 for example by means of bolts 7. The bearing caps 3b have a substantially inverted U shape whose ends of the branches are

  integral with the stiffening bars 6. Thus, two elements are obtained.

  stiffening rings for the crankshaft bearings 3.

  The cylinder block 2 laterally has two flanges longitu-

  dinales 2c to allow the fixing of an oil pan 8 in the form

  a large bowl made of flexible material. Oil 9 in the oil pan

  the 8 is intended for the lubrication of the engine, and is recycled by means of a suitable circuit not shown. At the side flanges 2c there are four side hooking elements 10 allowing

  the attachment of the engine to the chassis of the vehicle not shown.

  The internal structure of the engine constituted by the cylinder head 1, the cylinder block 2, the crankshaft bearings 3, the hanging skirts 4 and the stiffening bars 6 is rigid. The external structure of the engine

  constituted by the large bowl 8 is flexible and mechanically decoupled

  rigid internal structure. The stiffening bars 6 per-

  stiffen the crankshaft bearings 3 into a solid block to prevent their vibrations caused by engine operation

  (movement of the pistons in the cylinders and movement of the crankshaft-

  quin). The vibrations of cylinder block 2 are propagated mechanically-

  ment by the hanging skirts 4 whose lower end free radius-

  born. The granular material 5 contained in the internal pockets 4a of the skirts 4 makes it possible to dampen the vibrations by dry friction between the

grains of the material.

  Damping elements 11 are provided between the caps

  3b of crankshaft bearings 3 and the lower end of the skirts

  dantes 4, in order to dampen the vibrations radiated by said extremities

  free mites. The damping elements 11l are dynamic dampers.

  mics, for example viscous non-linear in character. So the struc-

  rigid internal motor structure ensures good vibration reduction

  tions, direct sources of noise emissions.

  The large bowl 8 is mechanically decoupled from the structure.

  rigid internal structure so that the vibrations of the internal structure of the motor are not transferred to the external environment. The big bowl

  8 is preferably made of flexible material, for example in

  posite, and constitutes an acoustic screen which encloses the inter-

  ne with their mechanical vibrations and noise emissions.

  It is possible to further improve vi performance.

  engine noise by modifying the structure of the pendant skirts

  tes 4. One solution is to replace the skirts in the form of

  than by several hanging beams 4b (Figure 3). These beams 4b pre-

  feel different dimensions to constitute absorbers dy-

  namic vibrations tuned in frequency. The damping of these beams 4b should take into account the characteristics of each beam in order to effectively cover the entire spectrum of vibrations at

  treat. Solutions for including granular materials in ju-

  pes 4 and / or dynamic dampers at the ends of the beams 4b can be used. Having tuned beams and dynamically damped, greatly reduced the radiation coefficient

  acoustic skirts 4 overall.

  Another solution (Figure 4) is to provide openings.

  side tures 4c in the hanging skirts 4. This also allows

  decrease the sound radiation coefficient of skirts during

dantes 4.

Claims (11)

  1. Internal combustion engine comprising a cylinder head (1), an elongated cylinder block (2), crankshaft bearings (3) below the cylinder block, and an oil sump (8), characterized in that the block cylinder extends downwards by two hanging side skirts (4) which do not come into direct contact with the crankshaft bearings, that the crankshaft bearings have bearing caps (3b) which are mechanically connected to each other others by two bars   stiffening (6) parallel, and that the oil pan (8) is in the form   me of a large bowl fixed suspended on two side flanges   (2c) along the cylinder block above the hanging skirts.   2. Motor according to claim 1, characterized in that the free lower ends of the hanging skirts (4) are connected to the bearing cap 3b) by means of the damping elements (1 1).   3. Engine according to claim 2, characterized in that the damping elements are constituted by non-linear viscous dampers 4. Engine according to claim 3, characterized in that the thickness of the oil film of the shock absorbers is less than or equal to 50   times the range of movement of the free end of the skirts due to vibrations.   5. Motor according to one of the preceding claims, character-   laughed at the fact that the hanging skirts have internal pockets (4a)   containing granular material (5).   6. Motor according to one of the preceding claims, character-   laughed at by the fact that the hanging skirts are made up of several   very hanging (4b) along the cylinder block.   7. Motor according to claim 6, characterized in that the   hanging beams (4b) are of different dimensions to each other   very and constitute dynamic absorbers tuned in frequency, so as to cover the spectrum of vibrations transferred from the block cylinder with hanging skirts.   8. Motor according to one of claims 1 to 5, characterized in   that the hanging skirts (4) have lateral openings (4c).   9. Motor according to one of the preceding claims, character-   in that the oil pan (8) is made of flexible material.   10. Motor according to one of the preceding claims, charac-   terized in that the oil pan (8) is made from a composite material.   11. Motor according to one of the preceding claims, charac-   that the oil pan (8) is mechanically decoupled from the block structure.