Method and apparatus for controlling engine exhaust sound for vehicles

Abstract

An exhaust sound controlling method including reducing a flow rate of exhaust gas that passes through an exhaust path, to a first flow rate in accordance with increase in engine speed in a first engine speed region, and increasing the flow rate of exhaust gas to a second flow rate in accordance with increase in engine speed in a second engine speed region higher in engine speed than the first engine speed region. An exhaust sound controlling apparatus including a baffle plate and a valve that is operated to open a communication passage that communicates upstream and downstream sides of the baffle plate in an engine starting region, close the communication passage in an idling region and a low engine speed region, and open the communication passage and increase an opening of the valve as the engine speed rises in a high engine speed region.

1 . A method for controlling exhaust sound from an engine which is emitted through an exhaust path, the method comprising:
 a first control step of reducing a flow rate of exhaust gas that passes through the exhaust path, to a first flow rate in accordance with increase in engine speed in a first engine speed region; and   a second control step of increasing the flow rate of exhaust gas to a second flow rate in accordance with increase in engine speed in a second engine speed region in which the engine speed is higher than that in the first engine speed region.   
   
   
       2 . The method as claimed in  claim 1 , further comprising a third control step of reducing the flow rate of exhaust gas to a third flow rate that is lower than the first flow rate and the second flow rate in a third engine speed region between the first engine speed region and the second engine speed region. 
   
   
       3 . The method as claimed in  claim 1 , wherein the engine speed in the first engine speed region comprises an engine speed in an engine starting region. 
   
   
       4 . The method as claimed in  claim 1 , wherein the engine speed in the second engine speed region comprises an engine speed in a high engine speed region. 
   
   
       5 . The method as claimed in  claim 2 , wherein the engine speed in the third engine speed region comprises an engine speed in an idling region. 
   
   
       6 . The method as claimed in  claim 2 , wherein the engine speed in the third engine speed region comprises an engine speed in a low engine speed region. 
   
   
       7 . An apparatus for controlling exhaust sound from an engine which is emitted through an exhaust path, the apparatus comprising:
 a baffle plate that is disposed within the exhaust path so as to block a flow of exhaust gas in the exhaust path, the baffle plate being formed with an aperture;   a communication passage that communicates an upstream side of the baffle plate and a downstream side of the baffle plate with each other;   a valve that is so disposed as to cover a part of the aperture of the baffle plate and operated to open and close the communication passage; and   wherein the valve is operated to open the communication passage in an engine starting region, the valve is operated to close the communication passage in an idling region and a low engine speed region, and the valve is operated to open the communication passage and increase an opening of the valve as the engine speed rises in a high engine speed region.   
   
   
       8 . The apparatus as claimed in  claim 7 , further comprising a means for cooperating with the valve to define the communication passage during the rotational movement of the valve. 
   
   
       9 . The apparatus as claimed in  claim 7 , further comprising a biasing means for biasing the valve toward the baffle plate. 
   
   
       10 . An apparatus for controlling exhaust sound from an engine which is emitted through an exhaust path, the apparatus comprising:
 a baffle plate that is disposed within the exhaust path so as to block a flow of exhaust gas in the exhaust path, the baffle plate being formed with an aperture;   a valve that is so disposed as to cover a part of the aperture of the baffle plate, the valve being rotationally moveable relative to the baffle plate so as to be apart from the baffle plate in a direction of the flow of exhaust gas,   a biasing means for biasing the valve toward the baffle plate; and   an enclosure member that extends from the baffle plate so as to be opposed to the outer periphery of the valve when the valve is moved relative to the baffle plate,   wherein the valve has a contact position in which the valve is contacted with the baffle plate and covers the part of the aperture of the baffle plate, a small distance position in which the valve is apart from the baffle plate in the direction of the flow of exhaust gas with a first distance therebetween, an intermediate distance position in which the valve is apart from the baffle plate in the direction of the flow of exhaust gas with a second distance therebetween which is larger than the first distance, and a large distance position in which the valve is apart from the baffle plate in the direction of the flow of exhaust gas with a third distance therebetween which is larger than the first distance and the second distance, and   wherein when the valve is placed in the contact position, the valve cooperates with the baffle plate to define an opening between the outer periphery of the valve and a periphery of the aperture of the baffle plate,   when the valve is placed in the small distance position, the valve cooperates with the enclosure member to define a first clearance between the outer periphery of the valve and an opposing surface of the enclosure member that is opposed to the outer periphery of the valve,   when the valve is placed in the intermediate distance position, at least a part of the outer periphery of the valve is substantially contacted with the opposing surface of the enclosure member, and   when the valve is placed in the large distance position, the valve cooperates with the enclosure member to define a second clearance between the outer periphery of the valve and the opposing surface of the enclosure member, and the second clearance is increased as the third distance between the valve and the baffle plate becomes larger.   
   
   
       11 . The apparatus as claimed in  claim 10 , wherein the biasing means has a biasing force that acts on the valve against a pressure of the exhaust gas that flows in the exhaust path, the biasing force urges the valve to move to the small distance position in an engine starting region, the biasing force urges the valve to move to the intermediate distance position in an idling region and a low engine speed region, and the biasing force urges the valve to move to the large distance position in a high engine speed region. 
   
   
       12 . The apparatus as claimed in  claim 10 , wherein the valve comprises a gas leakage inhibiting portion that prevents the exhaust gas and the exhaust sound from leaking from a support portion of the valve at which the valve is supported relative to the baffle plate, toward a downstream side of the baffle plate during the rotational movement of the valve. 
   
   
       13 . The apparatus as claimed in  claim 10 , further comprising a gas leakage inhibiting member that prevents the exhaust gas and the exhaust sound from leaking from a support portion of the valve at which the valve is supported relative to the baffle plate, toward a downstream side of the baffle plate during the rotational movement of the valve. 
   
   
       14 . The apparatus as claimed in  claim 10 , further comprising a first expansion chamber, a second expansion chamber that are separated from the first expansion chamber by the baffle plate, a first communication tube having one end that is connected to the engine and the other end that is opened within the second expansion chamber, a second communication tube having one end that is exposed to atmospheric air and the other end that is opened within the first expansion chamber, and a third communication tube that extends through the baffle plate and communicates the first expansion chamber and the second expansion chamber with each other, wherein the first and second expansion chambers are larger in sectional area than the first, second and third communication tubes. 
   
   
       15 . The apparatus as claimed in  claim 10 , further comprising a first expansion chamber, a second expansion chamber that is separated from the first expansion chamber by the baffle plate, a third expansion chamber, a second baffle plate that separates the third expansion chamber and the second expansion chamber from each other, an inlet tube having one end that is connected to the engine and the other end that is opened within the second expansion chamber, a first tail tube having one end that is exposed to atmospheric air and the other end that is opened within the first expansion chamber, a second tail tube having one end that is exposed to atmospheric air and the other end that is opened within the second expansion chamber, a first pass-through tube that extends through the second baffle plate and communicates the second expansion chamber with the third expansion chamber, and a second pass-through tube that extends through the second baffle plate and communicates the third expansion chamber with the aperture of the baffle plate, wherein the first, second and third expansion chambers being larger in sectional area than the inlet tube, the first and second tail tubes and the first and second pass-through tubes.