GB2512449B

GB2512449B - An engine cover assembly

Info

Publication number: GB2512449B
Application number: GB1401391.6A
Authority: GB
Inventors: Timothy Evans Dominic; Rocca Gianpiero
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2013-02-28
Filing date: 2014-01-27
Publication date: 2019-07-31
Anticipated expiration: 2034-01-27
Also published as: GB2512449A; GB201401391D0; DE102014203501A1; CN203742783U; GB201303568D0

Description

AN ENGINE COVER ASSEMBLY

The present disclosure relates a cover assembly for an engine.

Background

With reference to Figure la, internal combustion engines, such as for automobiles, typically have a drive assembly 10 which transmits rotation from a crank shaft 12 to one or more cam shafts 14a, 14b. The drive assembly 10 may comprise a belt 16, chain or gear arrangement. The drive assembly 10 may further comprise an idler gear 17.

As the drive assembly between the crank shaft and cam shafts may be critical to the functioning of the engine, the drive assembly may be covered to protect it from the elements and prolong the life of the drive assembly. Referring to Figure lb, the drive assembly 10 is typically provided at one end of the engine and a cover 18 may be coupled to the engine to enclose the drive assembly 10. Accordingly, the cover 18 defines a chamber which accommodates the drive assembly 10.

It will be appreciated that noise is generated by the drive assembly when the engine is in use. For example, the drive assembly may excite oscillations in the air in the chamber and/or oscillations in the cover. Such oscillations may result in appreciable noise.

It is desirable to reduce the noise emitted from the engine, particularly in the case of an engine for an automobile, as this may affect passenger comfort. However, as the noise emitted from other engine components is reduced or engines are operated at higher speeds and/or torques (e.g. for emission control purposes), the noise emitted from the drive assembly between the crank shaft and cam shafts may become more significant.

The present disclosure seeks to address these issues.

Statements of Invention

According to an aspect of the present disclosure there is provided an engine cover assembly for an internal combustion engine, the engine cover assembly being configured to cover a drive assembly rotatably connecting a drive shaft, e.g. a crank shaft, of the internal combustion engine to at least one or more further shafts, e.g. a cam shaft, the engine cover assembly comprising a cover at least partially defining a chamber for accommodating the drive assembly, wherein the engine cover assembly comprises one or more acoustic resonators arranged so as to be in fluidic communication with the chamber defined by the cover, the acoustic resonators being configured so as to dampen acoustic oscillations, wherein the engine cover assembly comprises a first acoustic resonator and a second acoustic resonator, and wherein the first and second acoustic resonators are provided in a series arrangement with the second acoustic resonator being in fluidic communication with the chamber via the first acoustic resonator.

At least a portion of at least one of the acoustic resonators may be provided inside the chamber defined by the cover. For example, the acoustic resonator(s) may be provided entirely inside the chamber.

At least a portion of at least one of the acoustic resonators may be provided outside the chamber defined by the cover. For example, the acoustic resonator(s) may be provided entirely outside the chamber. A portion of a particular acoustic resonator may be provided outside the chamber and a further portion of the particular acoustic resonator may be provided inside the chamber defined by the cover.

Further acoustic resonators may be provided, e.g. in a series and/or parallel arrangement, such that there may be multiple resonators. For example, serial first and second acoustic resonators may be provided in a parallel arrangement with one or more further acoustic resonators. The first and further acoustic resonators may be in direct fluidic communication with the chamber.

The first acoustic resonator may be provided substantially inside the chamber. The second acoustic resonator may be provided substantially outside the chamber.

The first acoustic resonator may be tuned so as to dampen acoustic oscillations with a first frequency, e.g. a belt resonant frequency, a chamber acoustic resonant frequency or a cover structural resonant frequency. The second acoustic resonator may be tuned so as to dampen acoustic oscillations with a second frequency, e.g. a belt resonant frequency, a chamber acoustic resonant frequency or a cover structural resonant frequency. Further acoustic resonators may be tuned so as to dampen acoustic oscillations with a further frequency, e.g. a belt resonant frequency, a chamber acoustic resonant frequency or a cover structural resonant frequency.

At least one of the one or more acoustic resonators may be integral with reinforcing ribs provided on a wall, e.g. an inner or outer wall, of the cover. At least one of the one or more acoustic resonators may be at least partially formed by one or more reinforcing ribs provided on a wall of the cover. One or more walls of the acoustic resonator may be formed by the reinforcing ribs.

The acoustic resonators may comprise a cavity and an opening. The opening may be fluidically between the cavity and the chamber defined by the cover. The cavity and the chamber may be in fluidic communication via the opening. The acoustic resonators may comprise a neck portion. The neck portion may extend from the opening and into the cavity.

One or more of the acoustic resonators may be in fluidic communication with a region of the chamber with high amplitude oscillations when in use. One or more of the acoustic resonators may be in fluidic communication with a region adjacent to a flat plate portion of the cover.

The drive assembly may comprise a belt or chain and pulleys or gears. The belt or chain may be disposed about the pulleys or gears so as to transfer rotation from the drive shaft to the one or more further shafts. One or more of the acoustic resonators may be provided in a region adjacent to the belt or chain and/or between a first pulley or gear and a second subsequent pulley or gear. In particular, one or more of the acoustic resonators may be provided at one or more points of the belt or chain with a local maximum in a lateral displacement of the belt or chain, e.g. during vibrations at a critical vibration mode. The critical vibration mode may be the vibration mode that excites acoustic oscillations inside the chamber, e.g. with the most energy. For example, one or more of the acoustic resonators may be provided at a point of the belt or chain substantially midway between the first pulley or gear and the second subsequent pulley or gear, e.g. when the critical mode is the first vibration mode. This may be advantageous since this may be where the oscillations generated from the belt or chain span structural mode reaches a maximum amplitude value.

By way of example, one or more of the acoustic resonators may be provided in a region between an idler gear and the drive shaft. However, other locations for the one or more acoustic resonators are equally envisaged, for example, the resonators may be located at any point on, in or adjacent to the cover that may effectively dampen the acoustic pulsations.

One or more of the acoustic resonators may be tuned so as to dampen acoustic oscillations excited by belt or chain oscillations. In particular, one or more of the acoustic resonators may be tuned so as to dampen acoustic oscillations originating from an interaction between a structural resonance of a belt or chain of the drive assembly and an acoustic mode of the air inside the chamber.

The drive assembly may comprise a belt, e.g. a toothed belt, configured to transfer rotation from the drive shaft to the one or more further shafts. The drive assembly may comprise a chain configured to transfer rotation from the drive shaft to the one or more further shafts. The drive assembly may comprise one or more gears configured to transfer rotation from the drive shaft to the one or more further shafts.

The drive shaft may comprise a crank shaft, a motor shaft, or any other shaft providing rotational power. The one or more further shafts may comprise one or more cam shafts. The drive assembly may drive one or more accessories, such as a water pump, an (diesel) injection pump, a fuel pump, an oil pump, an alternator, a power-steering pump, an air conditioning pump or any other vehicle or engine accessory.

An engine and/or vehicle may comprise the above-mentioned engine cover assembly. The vehicle may comprise the above-mentioned engine and may additionally comprise a further engine. For example, the vehicle may be a hybrid vehicle with two different types of engine, e.g. an internal combustion engine and an electric motor.

Brief Description of the Drawings

For a better understanding of the present disclosure, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

Figure la shows a previously-proposed drive assembly for an internal combustion engine and Figure lb shows a cover for the previously-proposed drive assembly;

Figures 2a and 2b show front and back views respectively of an engine cover assembly for an engine according to a comparative example of the present disclosure;

Figures 3a and 3b show isometric and sectional views respectively of an engine cover assembly for an engine according to a further comparative example of the present disclosure; and

Figures 4a and 4b show isometric and sectional views respectively of an engine cover assembly for an engine according to an example of the present disclosure.

Detailed Description

With reference to Figure 2, an engine cover assembly 20 for an engine (not shown) is configured to cover a drive assembly 10. The engine comprises an internal combustion engine and may further comprise a motor, e.g. an electric motor. For example, there may be a combination of an internal combustion engine and an electric motor, e.g. in the case of a hybrid engine. The engine may comprise a housing and the drive assembly may be provided outside of the engine housing. The engine cover assembly 20 may cover the drive assembly 10 which may otherwise be outside the engine housing.

The drive assembly 10 rotatably connects a drive shaft, e.g. a crank shaft 12, of the engine to at least one or more further shafts, such as cam shafts 14a, 14b. The drive assembly 10 may further comprise an idler gear 17. The engine cover assembly 20 comprises a cover 22 at least partially defining a chamber 24 for accommodating the drive assembly 10.

The drive assembly 10 may comprise a belt 16, e.g. a toothed belt, configured to transfer rotation from the crank shaft 12 to the one or more cam shafts 14a, 14b. However, in alternative configurations, the drive assembly may comprise a chain or a gear assembly configured to transfer rotation from the crank shaft 12 to the one or more cam shafts 14a, 14b.

In addition or alternatively to the cam shafts 14a, 14b, the drive assembly 10 may drive one or more accessories, such as a water pump, an (diesel) injection pump, a fuel pump, an oil pump, an alternator, a power-steering pump, an air conditioning pump or any other vehicle or engine accessory.

As depicted in schematic form in Figures 2a and 2b, the engine cover assembly 20 according to a comparative example of the present disclosure comprises one or more acoustic resonators 30 arranged so as to be in fluidic communication with the chamber 24 defined by the cover 22. Figures 2a and 2b show front and back views of the cover assembly 20 and Figure 2b shows the cover assembly covering the drive assembly 10. The acoustic resonators 30 may be configured so as to dampen acoustic oscillations, e.g. that are excited by movement of the drive assembly 10, the engine cover assembly 20 and/or any other bordering component.

The acoustic resonators 30 may comprise a cavity 32 and an opening 34. The opening 34 may be fluidically between the cavity 32 and the chamber 24. In other words, the cavity 32 and the chamber 24 may be in fluidic communication via the opening 34. The acoustic resonators may comprise a neck portion 36 between the cavity 32 and the chamber 24. As depicted in Figure 2, the acoustic resonator 30 may be provided entirely outside the chamber 24, however, as described below, other arrangements are also envisaged.

With reference to Figures 3a and 3b, an engine cover assembly 120 according to a further comparative example of the present disclosure may comprise one or more acoustic resonators 130 provided inside a chamber 124 defined by a cover 122 of the cover assembly 120.

The acoustic resonators 130 may comprise a cavity 132 and an opening 134. The opening 134 may be fluidically between the cavity 132 and the chamber 124. In other words, the cavity 132 and the chamber 124 may be in fluidic communication via the opening 134. The acoustic resonators 130 may comprise a neck portion 136. The neck portion 136 may extend from the opening 134 and into the cavity 132.

The cover 122 may comprise one or more reinforcing ribs 126, which may stiffen the cover 122. The reinforcing ribs 126 may be provided on an inner wall 128 of the cover 122. The reinforcing ribs 126 may be substantially perpendicular to the inner wall 128 of the cover. The acoustic resonators 130 may be integral with the reinforcing ribs 126 provided on the inner wall 128 of the cover 122. For example, side walls 138 of the acoustic resonator cavity 132 may be formed by the reinforcing ribs 126. The opening 134 to the cavity 132 may be provided in a reinforcing rib 126 or between neighbouring reinforcing ribs 126. The acoustic resonators 130 may further comprise a lid 140, which, together with the side walls 138 and inner wall 128 of the cover, may form the cavity 132.

The reinforcing ribs 126 may stiffen the cover 122 and thereby dampen chamber wall oscillations, e.g. oscillations of a cover wall, at one or more frequencies. In addition, the reinforcing ribs 126 may provide structural stiffness to the cover, e.g. to ensure the rigidity of the cover.

Although Figure 3 shows that the acoustic resonator 130 may be provided entirely inside the chamber 124, it is also anticipated that a portion of a particular acoustic resonator may be provided outside the chamber and a further portion of the particular acoustic resonator may be provided inside the chamber. For example, a larger cavity may be provided by extending the cavity to a region outside of the chamber 124.

With reference to Figures 4a and 4b, an engine cover assembly 220 according to an example of the present disclosure may comprises acoustic resonators 230, 250 in fluidic communication with a chamber 224 defined by a cover 222 of the cover assembly 220. Features described with respect to the engine cover assembly 120 may apply equally to the engine cover assembly 220.

As depicted, the engine cover assembly 220 comprises a first acoustic resonator 230 and a second acoustic resonator 250. The first acoustic resonator 230 may be provided substantially inside the chamber 224. The second acoustic resonator 250 may be provided substantially outside the chamber 224.

The first acoustic resonator 230 may comprise a first cavity 232 and a first opening 234. The first opening 234 may be fluidically between the first cavity 232 and the chamber 224. In other words, the first cavity 232 and the chamber 224 may be in fluidic communication via the first opening 234. The first acoustic resonator 230 may comprise a first neck portion 236. The first neck portion 236 may extend from the first opening 234 and into the first cavity 232.

In a similar manner, the second acoustic resonator 250 may comprise a second cavity 252 and a second opening 254. The second opening 254 may be fluidically between the second cavity 252 and the first cavity 232. In other words, the second cavity 252 and the first cavity 232 may be in fluidic communication via the second opening 254. The second acoustic resonator 250 may comprise a second neck portion 256. The second neck portion 256 may extend from the second opening 254 and into the second cavity 252.

As for the engine cover assembly 120, the cover 222 of the engine cover assembly 220 may comprise one or more reinforcing ribs 226, which may stiffen the cover 222. The reinforcing ribs 226 may be provided on an inner wall 228 of the cover 222. The reinforcing ribs 226 may be substantially perpendicular to the inner wall 228 of the cover. The first acoustic resonator 230 may be integral with the reinforcing ribs provided on the inner wall 228 of the cover 222. For example, side walls 238 of the first cavity 232 may be formed by the reinforcing ribs 226. The first opening 234 to the first cavity 232 may be provided in a reinforcing rib 226 or between neighbouring reinforcing ribs 226. The first acoustic resonator 230 may further comprise a lid 240, which, together with the side walls 238 and inner wall 228 of the cover, may form the first cavity 232.

In contrast to the first acoustic resonator 230, the second acoustic resonator 250 may be provided substantially outside the chamber 224. Accordingly, the second acoustic resonator 250 may comprise one or more walls 258, which may be coupled to the cover 222 and form the second cavity 252. The second opening 254 to the second cavity 232 may be provided in a wall of the cover 222.

As depicted, the first and second acoustic resonators 230, 250 are provided in a series arrangement. In such an arrangement, the second acoustic resonator 250 is in fluidic communication with the chamber 224 via the first acoustic resonator 230. Furthermore, in an alternative arrangement (not shown), the serial first and second acoustic resonators 230, 250 may be provided in a parallel arrangement with one or more further acoustic resonators, the first and further acoustic resonators being in direct fluidic communication with the chamber 224.

In either case, the first acoustic resonator 230 may be tuned so as to dampen acoustic oscillations with a first frequency. The second acoustic resonator 250 may be tuned so as to dampen acoustic oscillations with a second frequency. Any further acoustic resonators may be tuned so as to dampen acoustic oscillations at the first, second or further frequencies. By way of example, the first, second and further frequencies may correspond to any of a belt resonant frequency, a chamber acoustic resonant frequency and/or a cover structural resonant frequency.

For any of the above-mentioned examples, the cavities, openings and/or neck portions may be dimensioned to tune the acoustic resonator to dampen a particular frequency.

For example: the cavity volume; opening cross-sectional area; and/or neck portion length and/or cross-sectional area, may be varied to dampen a particular frequency.

For any of the above-mentioned examples, the acoustic resonator may be in fluidic communication with a region of the chamber with high amplitude oscillations when in use. For example, the acoustic resonator may be in fluidic communication with a region adjacent to a flat plate portion of the cover. Alternatively or additionally, the acoustic resonator may be provided in a region adjacent to the belt 16 and/or between a first pulley or gear and a second subsequent pulley or gear of the drive assembly 10, such as an idler gear 17 and the crank shaft 12.

In particular, one or more of the acoustic resonators may be provided at one or more points of the belt or chain with a local maximum in a lateral displacement of the belt during vibrations at a critical vibration mode. For example, if the critical mode is a first vibration mode with one maximum lateral displacement of the belt, one or more of the acoustic resonators may be provided at a point of the belt 16 substantially midway between the first pulley or gear and the second subsequent pulley or gear, e.g. substantially midway between the idler gear 17 and the crank shaft 12. If, however, the critical mode is a second vibration mode with two maximum lateral displacements of the belt, then one or more of the acoustic resonators may be provided at points of the belt 16 substantially at A and/or % of the distance between the first pulley or gear and the second subsequent pulley or gear. More generally, if the critical mode is the n-th vibration mode with n maximum lateral displacements along the length of the belt, then one or more of the acoustic resonators may be provided at points of the belt 16 substantially at fractions of the distance between the first pulley or gear and the second subsequent pulley or gear defined by,

Accordingly, one or more of the acoustic resonators may be tuned so as to dampen acoustic oscillations excited by belt or chain oscillations. In particular, one or more of the acoustic resonators may be tuned so as to dampen acoustic oscillations originating from an interaction between a structural resonance of a belt or chain of the drive assembly and an acoustic mode of the air inside the chamber 24. In this way the resonator may tune the resonance of the air inside the chamber 24 so as to reduce the excitation of the air by the vibrating belt or chain (and thereby reduce the resulting noise).

Furthermore, placing the resonator adjacent to a flat plate portion of the cover may further reduce the excitation of the air. The flat plate portion of the cover may also oscillate and such oscillations may be excited by the air in the chamber. Oscillations of the flat plate portion of the cover may then also reinforce oscillations of the air in the chamber. Accordingly, placing the resonator adjacent to a flat plate portion of the cover may increase the damping effect and may thus further reduce the noise generated.

It will be appreciated by those skilled in the art that although the invention has been described by way of example with reference to one or more examples, it is not limited to the disclosed examples and that alternative examples could be constructed without departing from the scope of the invention as defined by the appended claims.

Claims

1. An engine cover assembly for an internal combustion engine, the engine cover assembly being configured to cover a drive assembly rotatably connecting a drive shaft of the internal combustion engine to at least one or more further shafts, the engine cover assembly comprising a cover at least partially defining a chamber for accommodating the drive assembly, wherein the engine cover assembly comprises two or more acoustic resonators arranged so as to be in fluidic communication with the chamber defined by the cover, the acoustic resonators being configured so as to dampen acoustic oscillations, wherein the engine cover assembly comprises a first acoustic resonator and a second acoustic resonator, and wherein the first and second acoustic resonators are provided in a series arrangement with the second acoustic resonator being in fluidic communication with the chamber via the first acoustic resonator.

2. The engine cover assembly of claim 1, wherein at least a portion of at least one of the acoustic resonators is provided inside the chamber defined by the cover.

3. The engine cover assembly of claim 1 or 2, wherein at least a portion of at least one of the acoustic resonators is provided outside the chamber defined by the cover.

4. The engine cover assembly of any of claims 1 to 3, wherein the first and second acoustic resonators are provided in a parallel arrangement with one or more further acoustic resonators, the first and further acoustic resonators being in direct fluidic communication with the chamber.

5. The engine cover assembly of any preceding claim, wherein the first acoustic resonator is provided substantially inside the chamber.

6. The engine cover assembly of any preceding claim, wherein the second acoustic resonator is provided substantially outside the chamber.

7. The engine cover assembly of any preceding claim, wherein the first acoustic resonator is tuned so as to dampen acoustic oscillations with a first frequency and the second acoustic resonator is tuned so as to dampen acoustic oscillations with a second frequency.

8. The engine cover assembly of any of the preceding claims, wherein at least one of 5 the acoustic resonators is at least partially formed by one or more reinforcing ribs provided on a wall of the cover.

9. The engine cover assembly of any of the preceding claims, wherein the acoustic resonators comprise a cavity and an opening, the opening being fluidically between the 0 cavity and the chamber.

10. The engine cover assembly of claim 9, wherein the acoustic resonators comprise a neck portion, the neck portion extending from the opening and into the cavity.

11. The engine cover assembly of any of the preceding claims, wherein one or more of the acoustic resonators are in fluidic communication with a region of the chamber with high amplitude oscillations when in use.

12. The engine cover assembly of any of the preceding claims, wherein one or more 0 of the acoustic resonators are in fluidic communication with a region adjacent to a flat plate portion of the cover.

13. The engine cover assembly of any of the preceding claims, wherein one or more of the acoustic resonators are provided in a region between an idler gear and the drive 5 shaft.

14. The engine cover assembly of any of the preceding claims, wherein one or more of the acoustic resonators are tuned so as to dampen acoustic oscillations excited by belt or chain oscillations. 0

15. The engine cover assembly of claim 14, wherein one or more of the acoustic resonators are tuned so as to dampen acoustic oscillations originating from an interaction between a structural resonance of a belt or chain of the drive assembly and an acoustic mode of the air inside the chamber.

16. An engine comprising the engine cover assembly of any of the preceding claims.

17. The engine of claim 16 comprising the drive assembly, wherein the drive assembly comprises a belt or chain and pulleys or gears, the belt or chain being disposed about the pulleys or gears so as to transfer rotation from the drive shaft to the one or more further shafts, and wherein one or more of the acoustic resonators are provided in a region adjacent to the belt or chain and between a first pulley or gear and a second subsequent pulley or gear.

18. The engine of claim 17, wherein one or more of the acoustic resonators are provided at one or more points of the belt or chain with a local maximum in a lateral displacement of the belt or chain during vibrations at a critical vibration mode.

19. A vehicle comprising the engine cover assembly of any of claims 1 to 15 or engine of claims 16 to 18.