Patent Publication Number: US-2005121254-A1

Title: Device for establishing noise in a motor vehicle

Description:
This is a Continuation-In-Part of International Application PCT/EP03/03478 filed Apr. 3, 2003 and claiming the priority of German Application 102 23 875.8 filed May 29, 2002. 
    
    
     BACKGROUND OF THE INVENTION  
      The invention relates to a device for establishing noise in a motor vehicle comprising a housing which is divided by a sound transmission device into at least two spaces one of which is in communication with a gas carrying part of an internal combustion engine of the vehicle and the other is acoustically coupled to the interior of the vehicle.  
      Such a device is known from DE 44 35 296 A1. The purpose of such devices is to transmit the noises produced by the internal combustion engine more intensely to the driver of the motor vehicle, in particular during acceleration, in order, on the one hand, to provide for a more intensive driving experience and, on the other hand, to pass on more information concerning the load state of the engine to the driver.  
      The disadvantages of this known device, however, are its relatively low efficiency and the very inflexible transmission characteristics thereof.  
      DE 100 42 012 A1 attempts to improve the efficiency of the overall device. However, an optimum solution is still not offered, in particular since the transmission characteristics are still relatively inflexible.  
      In various applications it may be desirable to make the noise volume in particular of the transmission dependent on the load state of the engine, which is not possible however with the known devices.  
      It is therefore the object of the present invention to provide a device for establishing noise in a motor vehicle by means of which the transmission and in particular the volume of the noises produced by the engine in the interior space of the motor vehicle and/or the space adjoining the motor vehicle can be adjusted in certain driving situations.  
     SUMMARY OF THE INVENTION  
      In a device for establishing noise in a motor vehicle including a housing or hollow body which is divided by at least one sound transmission device into at least two spaces, of which one space is in communication via an inlet line with a gas-carrying line of an internal combustion engine arranged in the motor vehicle and the other space is acoustically coupled by means of an outlet line to at least one of an interior space of the vehicle or to the space surrounding the vehicle, a valve device is arranged in the inlet line and/or in the outlet line, which is capable of reducing the cross-section of the respective line in dependence on a control variable.  
      The valve device provided in according with the invention in the line leading to the housing or extending from it makes it possible to reduce the cross section of the respective line and in this way influence the noise level transmitted by the device according to the invention into the interior space and/or the space surrounding the motor vehicle.  
      The valve device is in this case subjected to a control variable, various control variables being usable depending on the application or the desired noise transmission by means of the device according to the invention.  
      In an advantageous embodiment of the invention, the control variable may be a pressure prevailing in the gas-carrying line. In this way, a dependence of the noise transmission on the respective load state of the engine is achieved, which makes it possible particularly advantageously for corresponding information concerning the load state of the engine to be passed on to the driver of the motor vehicle.  
      In this connection, the gas-carrying line may be an intake line leading to the engine, and a connecting line for tapping the pressure branches off the gas carrying line upstream of a throttle valve arranged in the intake line.  
      Tapping the intake line upstream of the throttle valve establishes a definite coupling of the transmitted noise to the position of the throttle valve, and consequently in principle to the position of the gas pedal, so that, in particular when driving in a sporty style, a corresponding noise transmission to the driver takes place.  
      A simple structural design in the case of this embodiment resides in an arrangement wherein the control line extends to the valve device, so that the valve device is directly acted on, and consequently activated by, the pressure in the intake line, which in turn depends primarily on the position of the throttle valve.  
      The invention will become more readily apparent from the description of exemplary embodiments presented below on the basis of the accompanying drawings: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows schematically the device for establishing noise in a motor vehicle according to the invention,  
       FIG. 2  shows the device of  FIG. 1  with a valve disposed in the inlet line which valve is in the open position;  
       FIG. 3  shows the device of  FIG. 2  with the valve device in the closed state; and  
       FIG. 4  is an enlarged view of the valve device of  FIG. 3 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       FIG. 1  shows an intake line  2  leading to an internal combustion engine  1 , generally a gas-carrying line, which is connected via an inlet line  3  to a device  4  for establishing in the vehicle noises as generated by the engine  1 . Instead of branching off from the intake line  2 , the inlet line  3  may also branch off from some other gas-carrying line of the engine  1 , that is for example from an exhaust line. Like the engine  1 , the intake line  2  and the inlet line  3 , the device  4  is located in a motor vehicle, which is not represented in its entirety, and is capable of influencing both the noise in an interior space  5  of the motor vehicle and in the surroundings of the same. The basic construction and operating principle of the device  4  are known for example from DE 100 42 012 A1.  
      The device  4  has a hollow body  6 , which is subdivided by a sound transmission device  7 , formed in the present case by a vibratable membrane  7   a , into two spaces, namely an inlet space  8  and an outlet space  9 . The membrane  7   a  consists of a gas-impermeable material, in order to prevent gas from flowing from the intake line  2  into the outlet line  10 .  
      The inlet space  8  is connected to the inlet line  3 , whereas an outlet line  10 , which, in the present case, leads to the interior space  5 , is connected to the outlet space  9 . However, it is also possible to connect the outlet line  10  to a space surrounding the motor vehicle, which is not represented herein. The noises induced in the intake line  2  by pressure surges or pressure differences are introduced via the inlet line  3  into the inlet space  8  of the hollow body  6 , whereby the sound transmission device  7  is acted on and induced to vibrate. When acted on in this way, the sound transmission device  7  vibrates with a natural frequency that is typical of it, which is passed on by the air located in the outlet space  9  to the outlet line  10 .  
      In the present case, a valve device  11  is disposed in the outlet line  10  for reducing the cross section of the outlet line  10 . In this way, the noise that is produced by the sound transmission device  4  and transported further by the outlet line  10  can be controlled such that, the transmitted volume is reduced by a reduction in the cross section of the outlet line  10 . The valve device  11  is controlled in dependence on a control variable, which is discussed in more detail below.  
      In the embodiment of the device  4  according to  FIG. 2 , the valve device  11  is arranged in the inlet line  3  branching off from a collecting tank  2   a  which is known per se and adjoins the intake line  2 , and is consequently capable of reducing the cross section of the inlet line  3 . In principle, a valve device  11  may be located in the inlet line  3  and/or the outlet line  10 . Upstream of a throttle valve  12  arranged in the inlet line  2  there branches off a control line  13 , which extends to a housing  14  of the valve device  11 . In the state represented, the throttle valve  12  is open, which is the case whenever the driver accelerates and the engine  1  is operated with full load or at least with a high load. With the throttle valve  12  open the same pressure prevails in the control line  13  as in the intake line  2 , the inlet line  3 , the valve device  11  and the inlet space  8 , so that there are no pressure differences and accordingly the cross section of the inlet line  3  is not reduced, so that the noises present in the intake line  2  can reach the sound transmission device  7  un-throttled. This is appropriate or desired in the open state of the throttle valve  12 , since it is specifically in the loaded state of the engine  1  that the driver wishes to be supplied with the previously described acoustic information from the engine  1 .  
      If, however, the throttle valve  12  is in the closed state, as is shown in  FIG. 3 , the pressure in the control line  13  branching off upstream of the throttle valve  12  is higher than in the intake line  2 , the inlet line  3  and the valve device  11 . In this position of the throttle valve  12 , the way in which the valve device  11  is acted on by the control line  13  leads to the closing of the valve device  11 , and consequently to reduction of the cross section of the inlet line  3 , as illustrated below. As a result, in the closed state of the valve device  11 , the noises produced in the intake line  2  are no longer passed on into the inlet space  8 , and consequently to the sound transmission device  7 , or only at a greatly throttled level, whereby, in a low-load state of the engine  1 , the driver of the motor vehicle only receives a low-level acoustic feedback, or none at all, from the engine  1 .  
      Both in  FIG. 2  and in  FIG. 3 , the sound transmission device  7  is not formed by a membrane  7   a  but by a vibratable element  7   b , which can vibrate about a pivot point  7   c , and consequently directs the sound waves from the inlet space  8  into the outlet space  9 . The pivot point  7   c  is located on an acoustically inactive wall  7   d , which separates the inlet space  8  from the outlet space  9  and consequently, like the membrane  7   a  described above, prevents a flow of gas from the intake line  2  to the outlet line  10 .  
       FIG. 4  shows the actual configuration of the valve device  11 , which has a flexible hose line  15 , which is arranged in the housing  14  and the clear width of which, as represented, is reduced when it is subjected to pressure via the control line  13 , possibly to the extent that the passage through the inlet line  3  is completely blocked. This can be influenced by the choice of the material of the hose line  15 , which may for example consist of silicone. In order to retain the flexible hose line  15  in the housing  14 , the hose line is clamped between the housing  14  and two pieces of pipe  16  and  17 , which are arranged in the housing  14  and are axially spaced apart from each other.  
      In an embodiment as indicated in  FIG. 1 , the control line  13  is connected to a pressure measuring and control device  18  or the like, which senses the pressure and controls opening and closing of the valve device  11 , depending on the pressure in the control line  13 . In all cases the valve device can be formed both as an open-close valve and as a rate-controllable valve.  
      Furthermore, other control variables could also be used for the opening and closing of the valve device  11 , for example a pressure prevailing in the exhaust line or else a variable to be determined by the driver of the motor vehicle. It is also conceivable to provide adaptive control for the valve device  11 , so that the noise produced by the device  4  and directed into the interior space  5  or the space surrounding the motor vehicle is controllable, for example, depending on the driving style of the driver.