FR2569007A1 - DEVICE FOR TRANSMITTING STRUCTURAL NOISE FROM AN INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

TO TRANSMIT THE STRUCTURAL NOISE OF AN INTERNAL COMBUSTION ENGINE WITH MULTIPLE CYLINDERS CAUSED BY THE INTERNAL NOISE OF THE ENGINE, IN PARTICULAR FOLLOWING DETONATING COMBUSTION, A STRUCTURAL NOISE TRANSMISSION DEVICE WHICH ALLOWS A DISTORTIONLESS TRANSMISSION . FOR THIS PURPOSE, WE FIX ON THE OUTER WALL OF THE ENGINE2 A TETON4 AS A TRANSMISSION OF THE STRUCTURAL NOISE FOR EACH CYLINDER1; THE TABS ARE CONNECTED TOGETHER BY A BARRETTE5 ON WHICH A DETECTOR6 IS FIXED IN THE MIDDLE.

Description

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  The invention relates to a device for transmitting structure-borne noise which is caused by noise in an internal combustion engine and is picked up by a detector.

  placed outside on the engine.

  Such a device requires for multi-cylinder engines a detector for each cylinder. If, in engines with several cylinders, a detector is fixed on the external wall transmitting the structural noise, it is only difficult to recognize with certainty a knock phenomenon in a cylinder distant from the detector. Uniform detection for all cylinders is not possible, since the irregular structure of the wall of the combustion chamber causes strong

  distortion of vibrations of structure-borne noise.

  The object of the invention is, using a single detector

  tor, to provide a device allowing a uniformly reliable detection for all the cylinders so that from the detector signal one can draw conclusions for all the cylinders with regard to operations

  defective, for example knocking or damaged valves.

  This object is achieved in accordance with the invention by the fact that the outer wall of the motor is placed on

  internal combustion, for each cylinder a transmission member

  structure noise transmission and the structural noise transmission members are connected together by a bridge on which the detector is fixed. By fixing on the external wall of the internal combustion engine on the cylinder block or on the cylinder head for each cylinder a member for transmitting structural noise, and by connecting these members for transmitting structural noise by a bridge on which is fixed a detector, transmission of structural noise to the detector

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  becomes independent of the structure of the motor wall The structural noise captured by the detector provides a significant image of the noise entering inside the motor wall, for example of a noise which occurs

  in one of the cylinders in the event of explosive combustion.

  Simple geometrical shapes are appropriately chosen for the configuration of the structural noise transmission members and of the bridge, the vibration transmission behavior of which can be calculated. Preferably, O is used as structures for transmitting the noise of the structure of the studs which are either integral with the external wall of the engine and connected by ribs to the cylinders or screwed into the walls of the cylinders and passing through

  the outer wall with an elastic seal.

  In both cases, a bar of rectangular or round section is placed on the front faces of the nipples, which can make free bending in the area between the support locations. In the middle of the bar in a freely vibrating place with large amplitudes of vibrations, is fixed the detector made in a known manner so as to react to accelerations at the mounting place

of the bar.

  For engines with an odd number of cylinders, there is provided, mounted parallel to the bar on intermediate pieces, a second bar on which

the detector is fixed.

  Furthermore, one can also provide for engines having an even or odd number of cylinders a

  second bar fixed by means of interchangeable parts

  laires parallel to the first and on which is

attached the detector.

  The efficiency of the transmission of structural noise can be further improved by determining the dimensions of the structural noise transmission device by an appropriate choice of material so that its specific frequency at the location of the mounting of the detector, during the punctual excitation by the structural noise transmission members, is substantially equal to the frequency of the structural noise to be transmitted, from which it follows that

  due to resonance, an amplitude of vi-

  maximum brations. At the location of the agreement of reso-

  nance, there can be subcritical excitement,

  for which the natural frequency of the transfer device

  mission is higher than the frequency of the structure-borne noise

  essential for detecting noise.

  The invention will be clearly understood on reading the

  detailed description, given below as an example

  only, of embodiments shown diagrammatically

  tick on the drawing, on which:

  Figure 1 shows an internal combustion engine

  water-cooled, fitted with a transfer device

  structure noise mission; Figure 2 is a top view of a first embodiment according to Figure 1; Figure 3 is a top view of a second embodiment of the transmission device according to Figure 1; Figure 4 is a top view of a third embodiment of the transmission device

according to figure 1.

  Figure 5 shows a detail A; FIG. 6 represents a detail B as a variant of A;

  FIG. 7 represents an internal combustion engine

  water-cooled, fitted with a transfer device

structure noise mission;

  Figure 8 shows a detail C, preliminary assembly

  re of the detector; Figure 9 shows a detail D, like C, however after the final assembly; Figure 10 shows a detail E; FIG. 11 is a top view of a first embodiment of the device for transmitting the structure product in FIG. 7;

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  Figure 12 is a top view of a second embodiment of the transmission device according to Figure 7 Figure 13 is a top view of a third embodiment of the transmission device according to Figure 7; and Figure 14 shows a detail F. The four cylinders 1 of a water-cooled internal combustion engine are connected with the outer wall 2 1o by ribs 3 in the extensions of which are poured, outside on the outer wall 2, four pins 4 on the recesses 4 'of reduced diameter, from which is threaded and screwed a bar 5 of rectangular section. Halfway up the bar 5 is fixed

  a detector 6 which is used to detect knock.

  In a first embodiment according to FIG. 2, the detector 6 is fixed directly to the bar at mid-length and at half-width thereof. In a second

  embodiment according to FIG. 3, it is mounted in parallel

  connection to the bar 5 a second bar 7 which is connected to the first bar 5 by three ribs 8. The detector 6 is fixed to the second bar 7 in the region of the middle rib. On the bar 5 are fixed, according to Figure 4, four ribs 9, the bores 10 of which pass through the recesses 4 'of the studs 4. In the middle between the

  middle ribs 9 is fixed the detector 6.

  Instead of the nipples 4 cast, shown enlarged in FIG. 5, one can also provide nipples 11 which are screwed from the outside into the walls of the cylinders -1. In order to be able to pass the studs through the outer wall 2, in a sealed manner and not influenced by the structural noise, threaded sleeves 12 are screwed into the outer wall on which nuts 13 are screwed. In the nuts 13 are placed seals

  toric 14 which surround the nipples 11.

  In an internal combustion engine, as shown schematically in Figure 7, three cylinders are arranged isolated. On the outside, on the walls of cylinders 16 are studs or welded studs 17. On the studs 17 is placed the bar 5 and it is fixed so that a different expansion of the motor and of the bar can be compensated. To reach this goal,

  the bar 5 is simply screwed onto the median stud.

  To ensure the connection with the two external studs, these have spherical recessed parts around which penetrate intermediate pieces provided with an enlarged contact surface, on which the bar rests is mechanically maintained. In order to be able to adjust the force of the application pressure, an interval a is provided on the screw connection of the central stud 17 whose dimensions are such that, after blocking

  of the screw, the mechanical connection with the external cylinders

  laughing is enough to ensure perfect transmission of structural noise. To prevent the bar 5 from sliding laterally, its ends are made cylindrical and they are housed in corresponding cavities of

  inserts 19, made on a lathe.

  Instead of these mechanical connections by ball joints, one can also choose a spring connection as shown in FIGS. 13 and 14. On the bar 5 is fixed in the middle a rib 20 in the area of which the detector 6 is screwed. two outer ribs 21 have rectangular recesses 22 in which the bar 5 is held by cooperation of shapes and can move. The mechanical connection is established here by a curved leaf spring 23 which is placed in a groove 24 of the bar 5 and applies this against the

ribs 21.

  J 'The variants of the structural noise transmission device of FIGS. 11 and 12 are produced in a similar manner to those of FIGS. 2 and 3; in one case, the detector 6 is screwed directly onto the bar 5; in the other case according to FIG. 12, the detector 6 is fixed on a second strip 7 which is parallel to the first

  bar 5 and is connected to it by two ribs.

  In engines having two rows of cylinders, provision is made to fix one bridge per row of cylinders and to connect the two bridges with another bridge. The detector

is fixed on the connecting bridge.

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Claims (4)

R E V E N D I C A T I O N S   1. Device for transmitting structural noise   re caused by noise in an internal combustion engine   multi-cylinder to a detector placed outside   on the engine, characterized in that, a transmission member   Structural noise emission (4,11) is provided for each cylinder (1,15), which is connected to said cylinder by the shortest sound path and that the structural noise transmitters (4,11) are connected together by a bridge   (5) on which the detector (6) is fixed.   2. Device according to claim 1, characterized in that, on the outer wall (2) of the combustion engine   internal, are fixed in the area of the cylinders (1,15) of the   radial tones on the front side of which is fixed a bar- rette (5).   3. Device according to claim 2, characterized in that the bar (5) is connected by ribs (8) to a second parallel bar (7) on which the detector   is fixed at mid-length of the row of cylinders.   4. Device according to one of claims 1 to 3,   characterized in that its natural frequency at the location of the   tage of the detector (6) may be greater than or equal to the frequency   quence of vibrations of the structure-borne noise transmitted to it   punctually put on by noise transmission devices of structure.