Abstract:
A noise damper for a compressed air device includes a tubular housing part provided with an air inlet and an inserted insulating material, in particular, an inserted knitted fabric roll. The air inlet is embodied in the envelope of the tubular housing part such that the supplied air tangentially flows through the insulating material or the knitted fabric roll, is radially deviated inside the tubular housing part, and axially flows out from at least one end of the tubular housing part.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an improved noise damper for compressed air devices. 
     From DE 102 48 183 A1 it is known that insulating materials can be used in the form of a knitted fabric roll in noise dampers of compressed air devices. Such a knitted fabric roll is made from a tubular knitted fabric produced on a circular knitting machine from warp knit thermoplastic fibres having, for example, rectangular cross section, by cutting a knitted fabric tube to a predetermined length and heat sealing it at its cut faces in such a way that a rectangular tubular portion is obtained. This rectangular tubular portion is then rolled up to obtain a knitted fabric roll. The knitted fabric roll is then pushed into a connecting tube leading to the atmosphere. Aside from the fact that it is necessary to use an additional connecting tube, which requires a large amount of installation space, and that it is necessary to take additional measures to ensure that the knitted fabric roll is held sufficiently in place in the connecting tube, the resulting noise damping is not satisfactory. 
     DE 42 37 630 A1 describes a compressed air venting device that has a primary air path routed from an inlet of a housing via noise damping means to an outlet, and a secondary air path provided parallel thereto and comprising a first sub-channel extending from the inlet and a second sub-channel formed by the outlet or leading to the outlet. The two sub-channels are not filled with the noise damping means. The two sub-channels are in communication with one another via the noise damping means. The two sub-channels and that part of the noise damping means which places the two sub-channels in communication are arranged in such a way that such part of the noise damping means opens up a direct communication path between the two sub-channels when a dynamic pressure is admitted. The noise damping means are formed by a filtering knitted fabric, which comprises a stocking-like woven part of plastic flat wire, which is wound in the form of a roll. The housing is composed of one housing part resembling a pot and another housing part formed as a cover to be snapped thereon. A disadvantage of this compressed air venting device used as a noise damper is that the danger of leaks causing a loud noise level exists at the joints of the housing parts. Moreover, the known device is relatively bulky, and therefore requires considerable installation space. 
     SUMMARY OF THE INVENTION 
     Generally speaking, in accordance with the present invention, an improved noise damper for compressed air devices, especially for vehicle air-brake systems, is provided which overcomes disadvantages associated with conventional noise dampers. The inventive noise damper achieves superior noise damping while simultaneously permitting high venting gradients, which can be installed in the vehicle even under very confined space conditions and which can be manufactured simply. 
     The noise damper according to embodiments of the present invention includes a tubular housing part provided with an air inlet and an inserted insulating material, in particular, an inserted knitted fabric roll. The air inlet is embodied in the envelope of the tubular housing part such that the supplied air tangentially flows through the insulating material or the knitted fabric roll, afterwards, is radially deviated inside the tubular housing part and axially flows out from at least one end of the tubular housing part. 
     Still other objects and advantages of the present invention will in part be obvious and will in part be apparent from the specification. 
     The present invention accordingly comprises the features of construction, combination of elements, and arrangements of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be described in more detail hereinafter on the basis of the accompanying drawings, wherein: 
         FIG. 1  is a perspective side view of a noise damper in accordance with a preferred embodiment of the present invention with a view of an air-inlet nozzle; 
         FIG. 2  is a sectional view taken along line A-A of the embodiment of the noise damper depicted in  FIG. 1 ; 
         FIG. 3  is a sectional view taken along line B-B of the embodiment of the noise damper depicted in  FIG. 2 ; 
         FIG. 4  depicts a noise damper in accordance with an alternative embodiment of the present invention; 
         FIG. 5  depicts a noise damper in accordance with another alternative embodiment of the present invention; 
         FIG. 6  depicts a noise damper in accordance with yet another alternative embodiment of the present invention; and 
         FIG. 7  depicts a noise damper in accordance with a further alternative embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, where like and corresponding components are represented with like reference numerals,  FIG. 1  shows a noise damper  2  according to a preferred embodiment of the present invention with a housing  4 , including a central tubular part  6  and two cylindrical housing caps  8 ,  10 , which are mounted, preferably by snap fit, on the ends of tubular housing part  6  and can also be removed therefrom. 
     Housing caps  8 ,  10  are provided with cap bases  12 ,  14  and cylindrical jackets  16 ,  18 , respectively. Radial slots  20 ,  22  are formed in cap bases  12 ,  14 , respectively. Slots  20 ,  22  extend over respective transition regions  24 ,  26  into parts  16 ′,  18 ′ of jackets  16 ,  18  adjacent to the cap bases and form outlets  28 ,  30  of noise damper  2 . 
     Tubular part  6  of housing  4  is provided with a molded-on, centrally disposed inlet nozzle  32  with inlet opening  33  for compressed air and two flanges  34 ,  36  with mounting holes  38 ,  40 , with which noise damper  2  can be disposed on the housing of a vent valve (not shown), for example, such that inlet nozzle  32  can be connected practically directly to the valve outlet. 
     As shown in  FIGS. 2 and 3 , in tubular housing part  6  and both housing caps  8 ,  10  there are inserted noise damping means, preferably, knitted fabric rolls  42 ,  44 ,  46 . 
     Inlet nozzle  32  is constructed and arranged such that the air to be discharged to the atmosphere flows in at the middle of the tubular housing part, substantially tangentially relative to knitted fabric roll  42 , then is deflected radially toward both sides, flows axially through knitted fabric roll  42  of housing part  6  and the two knitted fabric rolls  44 ,  46  of housing caps  8 ,  10 , and, finally, flows out of outlets  28 ,  30 . By virtue of the two air streams emerging in opposite directions into the atmosphere, this construction of the noise damper acts as an acoustic dipole radiator. 
     Alternatively, tubular housing part  6  can be equipped with only one housing cap and can be constructed in closed form on one side, so that the air flowing into noise damper  2  is deflected radially to only one side and flows out axially from only one outlet. Such a noise damper acts as an acoustic monopole. 
     By means of the noise damper according to embodiments of the present invention, the turbulent flow in the free air jet is influenced to the effect that sound emission during a venting operation is reduced, or noise or sound damping is increased, while the necessary functions are provided in the existing installation space and, in particular, the specified venting times after braking operations are complied with. 
     The inventive noise damper can be manufactured simply from plastic, for example, in which case a housing cap can also be formed in one piece with the tubular housing part. One cap is preferably mounted detachably, so that replacement of the knitted fabric rolls is possible. The inventive noise damper is very compact, and so installation in the vehicle is possible even under very confined space conditions. 
     The foregoing advantages are also achieved by the modified embodiments of the inventive noise damper described below. 
     In one modified embodiment depicted in  FIG. 4 , in addition to outlets  28 , of housing caps  8 ,  10 , at least one further outlet opening  50  is disposed in tubular housing part  6 . 
     In another embodiment depicted in  FIG. 5 , only at least one further outlet opening  50  is formed in tubular housing part  6 , while housing caps  8 ,  10  do not have any outlets and are therefore closed. 
     According to a further embodiment depicted in  FIG. 6 , at least one of housing caps  8 ,  10  is dispensed with, preferably by providing a closed cap-free end on tubular housing  6 . 
     According to yet another embodiment depicted in  FIG. 7 , both housing caps  8 ,  10  are dispensed with or, if the caps are formed in one piece with the tubular housing part, closed ends or closed caps are formed at both ends of the tubular housing part. The knitted fabric roll can then no longer be replaced, but the noise damper produced in this form can be used as a disposable article, which can be justified by the low manufacturing costs for the housing. 
     Accordingly, the present invention provides, for compressed air devices, especially for vehicle air-brake systems, a noise damper which is extremely compact, is made of components that can be manufactured easily and substantially improves noise damping by means of novel air routing. Also, the inventive noise damper preserves the high venting gradient necessary for compressed air systems. 
     It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in the above constructions without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.