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Title:
SOUND INSULATION FOR ENGINE
Document Type and Number:
WIPO Patent Application WO/2003/044366
Kind Code:
A1
Abstract:
Generator set comprising a case−shaped housing in which a driven unit and a driving combustion engine, particularly a diesel engine, have been placed, a sound insulating assembly having been arranged at at least one side of the engine which assembly is supported on the engine, comprising at first layer of elastic, sound insulating material abutting the engine and a body having a mass, which body is supported at the side of the insulating layer facing away from the engine and is supported by the first insulating layer.

Inventors:
BRUIN HENDRIK JOHANNES (NL)
Application Number:
PCT/NL2002/000759
Publication Date:
May 30, 2003
Filing Date:
November 22, 2002
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
HOLDING H J BRUIN B V (NL)
BRUIN HENDRIK JOHANNES (NL)
International Classes:
F01N1/02; F01N1/06; F02B63/06; F02B75/16; F02B77/13; F04B17/05; F04B53/00; F02B75/18; (IPC1-7): F04B17/05; F01N1/02; F01N1/06; F02B63/06; F02B77/13
Domestic Patent References:
WO1999058824A11999-11-18
WO1998020237A21998-05-14
Foreign References:
US4048366A1977-09-13
DE9113113U11993-02-25
DE4202640A11993-08-05
US5276291A1994-01-04
Other References:
PATENT ABSTRACTS OF JAPAN vol. 2000, no. 23 10 February 2001 (2001-02-10)
PATENT ABSTRACTS OF JAPAN vol. 1997, no. 09 30 September 1997 (1997-09-30)
PATENT ABSTRACTS OF JAPAN vol. 2000, no. 24 11 May 2001 (2001-05-11)
PATENT ABSTRACTS OF JAPAN vol. 1996, no. 07 31 July 1996 (1996-07-31)
PATENT ABSTRACTS OF JAPAN vol. 018, no. 123 (M - 1568) 28 February 1994 (1994-02-28)
Attorney, Agent or Firm:
Ferguson, Alexander (P.O. Box 266, AW Den Haag, NL)
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Claims:
Claims
1. Generator set comprising a caseshaped housing in which a driven unit and a driving combustion engine, particularly a diesel engine, have been placed, a sound insulating assembly having been arranged at at least one side of the engine which assembly is supported on the engine, preferably the head of the engine, comprising a first layer of elastic, sound insulating material abutting the engine and a body having a mass, which body is situated at the side of the insulating layer facing away from the engine and is supported by the first insulating layer.
2. Device according to claim 1, the mass body extending over the layer of insulating material.
3. Device according to claim 2, the mass body being plate shaped.
4. Device according to claim 1,2 or 3, a second layer of sound insulating material having been arranged at the side of the mass body facing away from the engine.
5. Device according to any one of the preceding claims, the sound in sulating assembly being hoodshaped.
6. Device according to any one of the preceding claims, the first insulating layer being in surfacetosurface contact with the engine.
7. Device according to any one of the preceding claims, the mass body being of steel.
8. Device according to any one of the preceding claims, the sound in sulating material being a synthetic foam having open cells.
9. Device according to any one of the preceding claims, the driven unit being a fluid pump.
10. Assembly of a combustion engine, particularly a diesel engine, and a caseshaped housing around it, a sound insulating device having been arranged on the engine in a free supporting manner, comprising a first layer of elastic, sound insulating material abutting on and against the engine with surfacetosurface contact, and a body having a mass and situated at the side of the insulating layer facing away from the engine.
11. Assembly according to claim 10, the sound insulating device being provided with portions pendent over the sides of the engine and lying against it.
12. Assembly according to claim 11, the sound insulating device being hoodshaped.
13. Assembly according to claim 10, 11 or 12, the housing being provided with a lid above the engine, and the sound insulating device being con nected to the lid for moving along with it.
14. Assembly according to any one of the claims 1013, a second layer of sound insulating material being present, the mass body being situated between the first and the second layer of sound insulating material.
15. Generator set device comprising a caseshaped housing in which a driven machine, such as a pump, and a combustion engine, such as a diesel engine, for driving the machine have been placed, the engine having an exhaust system, having a first exhaust portion connected to the engine, and a second exhaust portion debouching in the surroundings outside the housing, as well as a resonance box connecting both exhaust portions to each other, which resonance box connects with a first opening to the first exhaust portion and with a second opening connects to the second exhaust portion, the resonance box being provided with separation means for dividing the space between both openings in several channels of different lengths that are arranged in parallel.
16. Device according to claim 15, the separation means being situated at a short distance downstream of the first opening.
17. Device according to claim 15, the separation means ending at a distance from the second opening.
18. Device according to claim 17, the separation means ending in an intermediate wall, in which for each channel a separate third opening is present, a common channel having been formed between the third openings and the second opening.
19. Device according to claim 18, the third openings being situated at different distances from the second opening, in a sequence corresponding to the sequence of the channels formed at the upstream side of the intermediate wall.
20. Device according to claim 18 or 19, the sum of the sizes of the third openings being smaller than the size of the first opening.
21. Device according to any one of the claims 1520, the second opening being smaller than the first opening.
22. Device according to any one of the claims 1521 the channels being parallel to each other.
23. Device according to claim 22, the channels being separated from each other by means of longitudinal partitions.
24. Device according to any one of the claims 1523, the combustion engine being a single or twin cylinder engine.
25. Device according to any one of the claims 1524, the resonance box being situated within the housing.
26. Device according to any one of the claims 1525, provided with a fluid pump, driven by the engine.
27. Resonance box suitable and intended for the device according to any one of the claims 1526.
28. Assembly of a resonance box according to claim 27 and sound muffler placed in series therewith, both contained as a unity in a case.
29. Device provided with one or more of the characterizing measures described in the attached description and/or shown in the attached drawings.
30. Resonance box provided with one or more of the characterizing measures described in the attached description and/or shown in the at tached drawings.
Description:
Sound insulation for engine The invention relates to sound or noise insulation for a combustion engine, particularly a diesel engine, as used in generator sets. The generator sets comprise a large housing in which the driven unit and the driving unit, the engine, have been placed. The engine mostly is a single or twin cylinder engine which causes a loud surging noise.

Such generator sets are for instance used in pumping water, in so-called drainage by well points.

In order to reduce the noise intensity outside the housing, which is par- ticularly desirable when the generator set is placed in the built-up area, the inside of the case is lined with a sound insulating layer, such as synthetic foam. In order to comply with the ever stricter noise standards, a thick layer has to be used to that end. However this has disadvantageous consequences for the size and the weight of the housing.

It is an object of the invention to make a considerable noise reduction possible, without the housing having to be adjusted to that end.

It is a further object of the invention to provide a generator set which compared to existing generator sets of the same type, results in a con- siderable noise burden reduction when in operation.

From one aspect the invention to that end provides a generator set comprising a case-shaped housing in which a driven unit and a driving combustion engine, particularly a diesel engine, have been placed, a sound

insulating assembly having been arranged at at least one side of the engine which assembly is supported on the engine, comprising a first layer of elastic, sound insulating material abutting the engine and a body having a mass, which body is situated at the side of the insulating layer facing away from the engine and is supported by the first insulating layer.

The mass-possessing body, in fact a weight-constituting body, here rests on the engine, that means immediately on the sound source, via an elastic, sound insulating layer. Sound muffling here takes place in two steps, the sound vibrations first being muffled in the first insulation layer and the sound vibrations that are transferred through the first insulation layer to the mass body being muffled by bringing the free supported mass body into motion.

Preferably the sound insulating material here is a synthetic foam having open cells.

Preferably the mass body extends over the first layer of insulating material, so that the sound muffling capacity is regularly distributed.

Preferably the mass body is plate shaped, as a result of which the structure height can remain limited. The plate may consists of steel which is a cheap and heavy material.

The noise reduction is further increased when a second layer of sound insulating material has been arranged at the side of the mass body facing away from the engine. Any sound vibrations released at the outside of the mass body are then muffled as well. A kind of sandwich structure has been achieved.

Preferably the sound insulating assembly surrounds the engine as much as possible, at least the area around the head of the engine. When the sound

insulating assembly is hood-shaped, sound muffling is realised in several directions in a structurally simple manner. It is preferred here that the hood surrounds the head of the engine to various sides: the portion of the engine producing the noise to be muffled is then immediately isolated.

For optimal muffling it is preferred that the first insulating layer is in surface-to-surface contact with the engine.

From another aspect the invention provides an assembly of a combustion engine, particularly a diesel engine, and a case-shaped housing around it, a sound insulating device having been arranged on the engine in a free supporting manner, comprising a first layer of elastic, sound insulating material abutting on and against the engine with surface-to-surface con- tact, and a body having a mass and situated at the side of the insulating layer facing away from the engine.

Preferably the sound insulating device has been provided with portions pendent over the sides of the engine and lying against it, particularly in the shape of a hood.

For facilitating the maintenance of the engine it is preferred that the housing has been provided with a lid above the engine, and the sound insulating device being connected to the lid for moving along with it. When the lid is swivelled open the sound insulating device is therewith lifted along away from the engine.

The application furthermore relates to a diesel generator set.

Such generator sets are used for many purposes, for instance for drainage by well points for carrying out civil constructional works. The generator set comprises a case which at the inside may be provided with sound muffling material, for reducing the noise coming from the driving combustion engine

and possibly the driven machine (s). A large part of the sound energy produced by the generator set is released at the exhaust side of the engine via the exhaust system. A problem here is that usually single or twin cylinder engines are used, which due to their operating cycle distribution cause a very irregular exhaust gas flow, the noise of which being difficult to absorb. It particularly regards the loud bangs, sound surges, originating from the often used single or twin cylinder engines.

When a generator set is placed in the built-up area, for instance for drainage by well points, high demands are made with regard to noise reduction. A standard for this is the noise intensity at a distance of 7 meters from the case. In known generator sets a level of 58 dB (A) is feasible, but in practice it has appeared that for people residing there and to others staying there this is still too high. It has been attempted to increase the noise intensity reduction by putting more insulating material at the inside of the wall of the case, the volume of the case of the generator set, however, thus becoming bigger and its weight increasing.

It is an object of the invention to improve on this in a simple manner.

To that end the application further provides a generator set device comprising a case-shaped housing in which a driven machine, such as a pump, and a combustion engine for driving the machine have been placed, the engine having an exhaust system, having a first exhaust portion connected to the engine, and a second exhaust portion debouching in the surroundings outside the housing, as well as a resonance box connecting both exhaust portions to each other, which resonance box connects with a first opening to the first exhaust portion and with a second opening connects to the second exhaust portion, the resonance box being provided with separation means for dividing the space between both openings in several channels of different lengths that have been arranged in parallel.

Thus noise reduction is achieved in a very simple and space-saving man- ner. By dividing the gas flow and thus the noise surges in several portions or waves and shifting them in time, the duration of the surge is lengthened, but the amplitude is reduced, and thus the noise intensity. As a result a more even gas flow having a lower noise intensity is realised. The sound in itself is utilised for achieving the noise intensity reduction. Special, expen- sive measures with respect to the case of the generator set are not neces- sary. Due to the achieved pressure equalisation the second exhaust portion, such as a sound muffler, is better able to absorb the remaining noise.

Preferably the separation means are situated at a short distance downstream of the first opening, as a result of which the distribution of the surge takes place within the resonance box, which enhances the noise reduction, reducing the amplitude of the resulting sound waves. When the distribution room is large, the resistance against distribution of the pressure wave over the channel entrances is kept low, which is advantageous for the expansion possibilities of the entering noise surge.

It is further preferred that the separation means end at a distance from the second opening.

In an embodiment the separation means end in an intermediate wall, in which for each channel a separate third opening is present, a common channel having been formed between the third openings and the second opening. The channels then in fact form several separate resonance chambers.

The surge distribution is further enhanced when the third openings are situated at different distances from the second opening, in a sequence corresponding to the sequence of the channels formed at the upstream side of the intermediate wall. The longest channels then connect to the

longest paths to the second opening.

The volume of the channels preferably is as large as possible, for an increased resonance action in the case.

Preferably the sum of the third openings is as small as possible, preferably smaller than the size of the first opening.

In an embodiment the channels are parallel to each other, and preferably separated from each other by longitudinal partitions. In this way a case can be divided in a simple way, and the strength is also increased.

The invention further relates to a resonance box suitable and intended for the device according to the invention described above.

Preferably the resonance box forms a unity with the sound muffler con- nected behind it.

The inventions will be elucidated on the basis of exemplary embodiments shown in the attached drawings, in which: Figure 1 shows a front view, broken away, of a pump generator set having a sound muffling assembly according to the invention; Figure 2 shows a detail of the engine of the generator set of figure 1, having a sound muffling assembly according to the invention; Figure 3 shows the generator set of figure 1, with an opened lid ; Figure 4 shows a front view, broken away, of a pump generator set having a resonance box according to the invention; and

Figure 5 shows an exemplary embodiment of a resonance box according to the invention.

The pump generator set 1 shown as an example in figure 1 comprises a housing 30, placed on a solid basis 20 by means of legs 21. In the housing 30 a pump 2 has been arranged, to which a suction line 4 and a pressure line 3 have been connected. The suction line 4 will in many cases be con- nected to a system for drainage by well points and the pressure line 3 will be connected to a pipe leading a surface water.

The pump 2 is a suction pump, having cylinder 5, in which a piston rod 7 is reciprocally movable. The piston rod 7 is driven by means of drive mechanism 6, which is driven by a single cylinder engine 8, by means of drive 22.

The exhaust gases of the engine 8 go to the exhaust pipe 19 via muffler 10 where they are released to the surroundings. At the upper side of the engine an hour counter 33 and a cooling air connection 34 are situated.

In the case 30 a lid 13 is situated above the engine, and at the front of the engine, as shown in figure 3, there is a door 11.

A sound muffling assembly 12 has been freely supported on the head 9, having filter 32, of the engine 8, which sound muffling assembly is substantially hood-shaped having an upper wall 23 and a circumferential wall 24, in which as can be seen in figures 2 and 3, wall members 24a, 24b, 24c, 24d and 24e can be distinguished. Note that the circumferential wall 24 and the upper wall 23 as well have been formed with a fitting shape to the head 9 and the filter 32 of the engine 8. Only at the front no pendent wall 24 is present as the resonance box 34 has been placed there.

It could be considered to move this box, and to provide the hood with a pendent wall 24 at the front as well. It is noted that in figure 1 the hood

12 is shown schematicaily only, like an U-shaped structure.

The hood 12 has been built up like a sandwich structure, having a layer 14 of synthetic foam having open cells, for instance polyester or polyether foam, a steel plate 15 lying on the foam layer 14, and a same synthetic foam layer 16 on the steel plate 15. Layers 14 and 16 have been adhered to the plate 15 with a suitable adhesive.

The hood 12 has been formed such in accordance with the head 9 of the engine 8, so that it is freely supported on it. The thicknesses of the layers 14 and 16 may be some centimetres. The thickness of the steel plate is several millimetres, for instance 2 to 3 millimetres, or more.

The hood 12 has been suspended from the lower side of the lid 13 of the housing 30 by means of rubber rings 17a, 17b at the location of suspen- sion points 18a, 18b.

In operation sound vibrations of the single cylinder engine 8 are partially absorbed in the synthetic foam layer 14. In the form of a spring-mass system non-absorbed vibrations are transferred to the plate 15. Bringing the relatively heavy plate 15 into motion results in further dissipation of the energy of the sound vibrations. The second synthetic foam layer 16 finally ensures absorption of sound vibrations that may be produced from the plate 15.

The weight of the plate 15 ensures that the foam layer 14 always remains in good contact with the head 9 of the engine 8. Due to its free position, the hood 12 does not produce vibrations transferred by contact to the construction parts of the housing 30. The hood 12 in fact vibrates freely.

The result will be such that at a point of measuring at a distance of 7 meters from the housing 30, a noise intensity reduction of 3dB (A) will be

feasible.

When the engine 8 has to be serviced the lid 13 is lifted into the position shown in figure 3, wherein cylinders 19a, 19b keep the lid in the upwardly inclined position. The hood 12 is also tilted upwards from the head of the engine 9, as a result of the now active connections 17a, 17b between hood 12 and lid 13. The front is then accessible by opening the door 11.

A pump generator set 101 shown in figure 4 comprises a housing 130 placed on a solid basis 120 by means of legs 121. In the housing 130 a pump 102 has been arranged, to which a suction line 104 extending from a side wall 109 and a pressure line 103 have been connected. The suction line 104 will in many cases be connected to a system of drainage by well points, and the pressure line 103 will be connected to a pipe leading to a surface water.

The pump 102 is a piston pump, having cylinder 105, in which a piston rod 107 is reciprocally moveable. The piston rod 107 is driven by means of drive mechanism 106, which is driven by a single cylinder engine 108 by means of drive 122.

A first exhaust pipe 119 ensures discharge of combustion gases of the engine 108 and runs to a case 110 in which a resonance box 130 and a sound muffler 131 have been accommodated in series, surrounded by thermal insulation 132, arranged in the right end wall 109 of the housing 130. At the location of the entrance opening 112, the pipe 119 has been connected to resonance box 110. The exit opening 113 of the resonance box 130 connects to the sound muffler 131 active on absorption. Exhaust stub 128 extends from the sound muffler 131, which exhaust stub debouches at the outside of the end wall 109.

As will be clarified in the discussion of figure 5, a number of channels 116

are present in the resonance box 130 for forming a connection between inlet opening 112 and exhaust opening 113.

In figure 5 the resonance box 130 is shown in broken away isometric view, longitudinal walls 114 and end walls 125 being distinguishable, as well as main walls 123,124. In between them they define a parallelepiped- shaped space. The inlet opening 112 is situated eccentrically, near a corner in the upper wall 123.

A special aspect of the resonance box 130 of figure 5 is that a number of- in this case two-longitudinal partitions 115a, 115b have been arranged, parallel to the longitudinal walls 114, in order to form three channels of equal cross-section 116a, 116b and 116c with them and each other. At their upstream end, the partitions 115a, 115b have been turned at a right angle by portions 127a, 127b which extend along with the flow, as considered from inlet opening 112, and reinforce the walls 115a, 115b to prevent material resonances (acoustic feedback).

The partitions 115a, 115b end in a transverse wall 118 which is parallel to the end walls 125, and defines a chamber 126 with the downstream end wall 125. The exhaust opening 113 is located in the bottom of the cham- ber 126, which exhaust opening has a cross-section which is smaller than the cross-section of the inlet opening 112. The exhaust opening 113 is situated near the longitudinal wall 114, near to which the inlet opening 112 is also situated, however in the other main wall.

The transverse wall 118 has been provided with three openings 117a, 117b and 117c, the sum of which being smaller than the opening 112.

They are situated near the bottom wall 124 and form a passage between the channels 116a, 116b and 116c and the chamber 126. The minimal passage in the openings 117a-c is defined by the maximum allowable counter pressure for the engine which depends on the type of engine,

stroke volume, rotational speed and load, as well as the size of the resonance chambers.

By means of partitions 115a, 115b it is achieved that the pressure surges in the exhaust system, as a result of the loud bangs of the engine, which in particular may be case with single cylinder engines, in the path of the inlet opening 112 to the exhaust opening 113 in the front chamber 135, are as it were cut into three parts, each having to go different path lengths. For instance in this case the first portion of the pressure surge will move in the direction B1 through channel 116a, a second portion in channel 116b in direction B2, and a third portion in channel 116c in the direction B3. Already at arrival at the location of the openings 117a, 117b, 117c the different portions of the pressure surge have traversed different path lengths. In this way a surge shifting is achieved, and the pressure surge is indeed lengthened, but with a lower noise intensity, which is what it is all about.

When combining the different pressure surge portions coming from the openings 117a, 117b and 117c, a further shifting takes place, as the different path lengths C1, C2, C3 are also different from each other, the sequence being the same, that means that C3 is larger than C2 is larger than C1, just like B3 is larger than B2, is larger than B1.

By means of the resonance box 130 of figure 5 pressure bangs from the engine prior to discharge from the exhaust opening 113 are spread/ distributed/equalised such that not only the noise intensity is lowered, but also the sound muffler connected to the exhaust opening 113 can be more effective.