VEHICLES

The Related Art

Invention relates to reduction of noise generated by road sweeping vehicles in external environment where people heavily live while working.

The invention particularly relates to silencers reducing noise generated by road sweeping vehicles and mountable to said vehicles at later stages.

Background of the Invention

Today particularly the biggest problem for road sweeping vehicles collecting the waste articles on road sides is that performing it by means of intake fan causes high noise pollution in environment. Noise levels should not exceed a specified level for such products in cities. Although there is no predetermined noise levels specified for such vehicles, public or private entities purchasing them require certain levels of noise for those products. So far there has been no works for reduction of noise caused by road sweeping vehicles.

Several studies have been conducted concerning noise problems of road sweeping vehicles in use today. However, there are no effective solutions on designing silencers at intake fan exit. In the vehicles in use today, the air sucked by the fan is supplied into a large volume and pressure of flowing is decreased. The decreasing in air pressure causes decrease in flow speed leading to slight reduction in noise emission. However, desired levels of reduction in noise could not be achieved.

When patent applications on the subject of the invention are reviewed, some applications are come across:

Patent application numbered US58391157 constituting sample in the related art discloses a modular system (collection head) design for the section taking thrash into vehicle for road sweeping vehicles. Inner surface of collecting head design is of nature reducing turbulence and border surface separations. The achieved designs reduce air speed change, thus decreases turbulence and noise levels. The silencer designed in the application is mounted before fan group. Therefore, higher noise levels are addressed in the area where the turbulence intensively occur. Another patent application numbered DE102010041441 discloses an adaptive noise control applied to road sweeping vehicles. The application of a sound generator is located in the section before inlet of fan and the place called outlet port. This generator is located in the middle of outlet port cross-section area. In addition, the information of the engine running in the vehicle (rpm etc.) is taken by control unit. Control unit generates sound signals to sound generator based on the information received from the engine and thus attempts to reduce fan noise. In case of change in engine data, controller generates sound according to coming new data and decreases noise. In our invention, the noise is reduced not by adaptive noise control but passive noise control at outlet port. In patent application numbered DE1020008005987, a jacket design is made for hydraulic pipe having flow inside. In this application sound absorber material is used inside the pipe for the sound reduction purpose. However, basically, sound absorber takes into account the orientation of material in the tube and generally orientations reducing flowing by means of increasing sound absorber material thickness. In our invention, sound absorber material thickness/orientation is not changed along tube axis. In addition, sound absorber material of our patent is located on the adjustable flaps.

Purpose of the Invention

From the related art current status, the purpose of the invention is to reduce the sound from fan part of machines known as road sweeping vehicles and thus to prevent occurrence of sound at disturbing levels.

Another purpose of the invention is to enable mounting of silencer providing reduction in sound of said vehicles onto vehicle as per choice.

A further purpose of the invention is to enable adjustment of silencer level by adjusting sound reduction mechanism in said vehicles. Brief Description of Figures

Figure 1 Is side view indicating mounting of silencer on vehicle.

Figure 2 Is perspective view of vertical flap silencer.

Figure 3 Is top view of vertical flap silencer.

Figure 4 Is top view illustrating the status when vertical flap silencer channels are fully open. Figure 5 Is top view showing the status when vertical flap silencer control shaft is pushed and flaps are in open position in channel.

Figure 6 Is perspective view showing full open position of horizontal flap silencer.

Figure 7 Is detailed view of mounting of flap and control shaft. Figure 8 Is detailed view of mounting of flap and coating on flap.

Reference Numbers

1. Silencer

2. Vehicle

2.1. Fan 2.2. Thrash absorption pipe

2.3 Thrash chamber

3. Flap

4. Silencer slot

5. Driving shaft

6. Control shaft

7. Mounting pin

8. Flap coating

9. tightening pin

Detailed Description of the Invention

The detailed description of the invention describes the characteristics and working principle of silencers (1 ) also mountable to current vehicles (2) later in order to reduce high noise generated by them during sweeping by machines called road sweeping vehicles.

Figure 1 shows information concerning said vehicle (2). The undesired articles such as thrash etc. on the road are taken into thrash chamber (2.3) via thrash absorption pipe (2.1 ). Vacuum force in the thrash absorption pipe (2.1 ) is provided by fan (2.1 ). However, a strong fan (2.1 ) is used because of high vacuum force need. Upon operation of the fan (2.1 ), very high noise is generated from top part of the vehicle (2). A silencer (1 ) can be mounted on outlet line section of the fan (2.1 ) as shown in figure 1. Working principle of the invention is: the silencer (1 ) mounted additionally to chamber in outlet of the fan (2.1 ) directs the flow into different channels and provide the sound wave to silencer slots (4) coated with sound absorbing materials. Thus noise level is reduced. In addition, size of silencer (1 ) is designed as adjustable according to dominant frequency of noise level. The silencer (1 ) shown in details in figure 2 provides increase of viscos losses during noise reduction (loss of friction in wall thickness of channels during the flow). The first member attracting attention in the silencer (1 ) shown in figure 2 is the silencer slots (4) and flaps (3). The flaps (3) are located in the silencer slots (4). The flaps (3) are of length minimum two times of wave length of dominant frequency of sound diffused inside silencer slots (4) coming from fan and are generated in trapezium wave form. The flaps (3) located in parallel to each other in the silencer slots (4) are positioned in a manner to provide air flow as shown in figure 3. Said flaps (3) can be in trapezium wave form as well as forms such as sinusoidal, saw tooth forms etc. Thanks to channel formed by the flaps (3) the sound is diffused in a smooth manner and progress in generated channel form. Thus the way in which sound is diffused gets longer and thus sound absorption provided by the viscos loss in the channels will increase. The most basic characteristic of the invention is based on that principle. The number of flaws formed inside silencer slots (4) by the flaps (3) depends on the geometry on which the silencer (1 ) is inserted. However, in case number of channels is low, the area of flap (3) on which sound flows and therefore sound reduction provided by friction on the flaps (3) will decrease. Furthermore, if higher number of channels and narrowness is used, that will decrease the suction power which is , the primary priority for road sweeping vehicles.

Figure 4 and figure 5 shows the silencer (1 ) view according to open and close positions of the flaps (3) in the silencer slots (4). However, open and close position of the flaps (3) is made manually and control shaft (6) is used for this operation. The connection between the control shaft (6) and flaps (3) is provided by a driving shaft (5). As seen in figure 4, when the control shaft (6) is at the most out (when pulled by user), the flaps (3) move towards walls of silencer slots (4) and silencer slots (4) the most open position is achieved. When it is desired to reduce the sound from the fan (2.1 ), control shaft (6) is moved in arrow directions as shown in figure 5. As a result of this motion, the flaps (3) moves as shown in figure 5 and formation of channels in silencer slots (4) is provided. An alternative embodiment regarding the control shaft (6) is to provide movement of said flaps (3) by turning the control shaft (6). Another detail to be noticed is that the number of flaps (3) is high and is interconnected at each bending point. Another factor increasing efficiency of the silencer (1 ) mechanism is the flap (3) coating (8) on the flaps as shown in figure 8. Flap coating (8) is placed on flaps (3), that is, surfaces where flow occurs in order to slow the flow down and provides sound absorption. Thus sound reduction is increased by flow speed reduction and by the sound absorption material. Such insulation materials are fixed onto the flaps (3) by tightening pins (9) as shown in figure 8. In addition, since the flaps (3) have rotation capability with respect to each other, sharp ends can be obtained at wave peaks according to wave form (trapezium wave, saw form wave). This case causes turbulence on flowing. Flap coating (8) laid on the flaps (3) is provided slightly more at wave peaks. With use of tightening pins (9) at wave peaks by use of extra materials, they are fixed in extra as shown in figure 8 and thus turbulence can be prevented. When the flap coating (8) can not be connected by tightening pin (9), it can be fixed by gluing.

Since the designed system can be used in vehicles such as road sweeping machines, the flap coating (8) material to be used should be made from materials of not only high sound absorbing characteristic but also dust-proof. Because the dust particles flowing under the flow should not cling to the material of this flap coating (8) and after a period of time it should not obstruct the way the air passes.For that reason, sound absorbing materials such as mat, glass wool, dust-preventing nano coated materials etc. can be used.

The connection principle of the drive shaft (5) and the flaps (3) is clearly seen in figure 7. The drive shaft (5) and the flap (3) are connected by means of the mounting pin (7) and a special housing is provided for this connection in the geometry of the flap (3).

In short, the sound wave generated upon start of sweeping operation of the vehicle (2) passes through multiple number of silencer slots (4) consisting of silencer (1 ) after chamber in fan (2.1 ) outlet and is divided into multiple channels. The flaps (3) located in the silencer slots (4) are driven by the control shaft (6) and formation of an additional channel inside the silencer slots (4) is provided. The noise directed to each silencer slot (4) by the help of flap coating (8) provided on the flaps (3) decreases.

The motion of the flaps (3) inside the silencer slot (4) can be activated by the user driving as described above, and also full automatic motion can also be conducted by the help of an electric engine upon instruction of fan (2.1 ) motion given from a sensor to reference area.

In the view shown in Figure 6, the flaps (3) perpendicular to lower and upper surfaces in previous pictures are located in a position where side surfaces are in perpendicular position. This design considered as alternative can be changed as preferred depending on place of use of the silencer (1 ).

Although the silencer (1 ) whose technical details and working principle are described above is designed mainly for use in road sweeping vehicles (2), it can also be used in all systems through which noisy flow passes. For instance, it is possible to use it in ventilation systems.