Exhaust pressure control valve

Abstract

An exhaust pressure control valve to be placed in an exhaust gas passage of a diesel engine for controlling pressure of exhaust gas to be discharged from the engine comprise: a housing formed with a main passage and a bypass passage; a main valve arranged to open and close the main passage; a bypass valve arranged to open and close the bypass passage; and an opening/closing drive device for opening and closing the bypass valve. The opening/closing drive device includes: a positive pressure actuator for opening and closing the bypass valve by pressure upstream of the main passage; and a negative pressure actuator for changing valve opening pressure of the bypass valve.

1 . An exhaust pressure control valve to be placed in an exhaust gas passage of an internal combustion engine for controlling pressure of exhaust gas to be discharged from the engine, the exhaust pressure control valve comprising:
 a housing formed with a main passage and a bypass passage;   a main valve arranged to open and close the main passage;   a bypass valve arranged to open and close the bypass passage; and   an opening/closing drive device for opening and closing the bypass valve;   wherein the opening/closing drive device includes:   a bypass valve opening/closing device for opening and closing the bypass valve; and   a valve opening pressure changing device for changing valve opening pressure of the bypass valve.   
   
   
       2 . The exhaust pressure control valve according to  claim 1 , wherein the valve opening pressure changing device comprises at least one actuator and is adapted to change the valve opening pressure of the bypass valve by setting an operation start pressure of the bypass valve opening/closing device higher than an initial set pressure and exerting a valve closing force that enhances the valve opening pressure of the bypass valve onto the bypass valve opening/closing device during an inactive state of the actuator, and releasing the valve closing force from the bypass valve opening/closing device during an active state of the actuator. 
   
   
       3 . The exhaust pressure control valve according to  claim 2 , wherein the actuator comprises:
 an introduction pipe for introducing pressure;   a pressure chamber for holding the pressure introduced therein through the pressure introduction pipe;   a movable member which forms part of the pressure chamber and can be displaced with the pressure changes;   an elastic member placed in a compressed state in the pressure chamber; and   a rod connected to the movable member and can be moved in association with displacement of the movable member.   
   
   
       4 . The exhaust pressure control valve according to  claim 3 , further comprising a ling member,
 wherein   the bypass valve includes a valve element and an arm attached to the valve element,   the arm is fixed to the link member rotatably coupled to the bypass valve opening/closing device, and   the valve opening pressure changing device is adapted to change the valve opening pressure of the bypass valve by moving the rod into or out of contact with the link member.   
   
   
       5 . The exhaust pressure control valve according to  claim 3 , further comprising:
 a ling member; and   a power drive element in the bypass valve opening/closing device,   wherein   the bypass valve includes a valve element and an arm attached to the valve element,   the arm is fixed to one end of the link member and the other end of the link member is rotatably coupled to the bypass valve opening/closing device, and   the valve opening pressure changing device is placed on the same side as the bypass valve opening/closing device relative to the link member and in series with the bypass valve opening/closing device so that the rod is moved into or out of contact with the power drive element.   
   
   
       6 . The exhaust pressure control valve according to  claim 4 , wherein
 the arm is attached to one end of the link member and the bypass valve opening/closing device is coupled to the other end of the link member, and   the valve opening pressure changing device is placed on an opposite side to the bypass valve opening/closing device relative to the link member and arranged so that the rod is moved into or out of contact with a connection part between the link member and the bypass valve opening/closing device.   
   
   
       7 . The exhaust pressure control valve according to  claim 4 , wherein
 the arm is attached to one end of the link member,   the valve opening pressure changing device is placed on the same side as the bypass valve opening/closing device relative to the link member and arranged so that the rod is moved into or out of contact with the other end of the link member, and   the bypass valve opening/closing device is coupled to the link member between a portion fixed to the arm and a portion contacting with the rod.   
   
   
       8 . The exhaust pressure control valve according to  claim 4 , wherein
 the bypass valve opening/closing device is coupled to one end of the link member,   the valve opening pressure changing device is placed on the same side as the bypass valve opening/closing device relative to the link member and arranged so that the rod is moved into or out of contact with the other end of the link member, and   the arm is fixed to the link member between a portion connected with the bypass valve opening/closing device and a portion contacting with the rod.   
   
   
       9 . The exhaust pressure control valve according to  claim 4 , wherein
 the bypass valve opening/closing device is coupled to one end of the link member,   the valve opening pressure changing device is placed on an opposite side to the bypass valve opening/closing device relative to the link member and arranged so that the rod is moved into or out of contact with the other end of the link member, and   the arm is fixed to the link member between a portion connected with the bypass valve opening/closing device and a portion contacting with the rod.   
   
   
       10 . The exhaust pressure control valve according to  claim 1 , wherein
 the valve opening pressure changing device comprises at least one actuator and is adapted to change valve opening pressure of the bypass valve by setting an operation start pressure of the bypass valve opening/closing device lower than an initial set pressure and exerting a valve opening force that reduces valve opening pressure of the bypass valve onto the bypass valve opening/closing device during an inactive state of the actuator, and releasing the valve opening force from the bypass valve opening/closing device during an active state of the actuator.   
   
   
       11 . The exhaust pressure control valve according to  claim 10 , wherein the actuator comprises:
 an introduction pipe for introducing pressure;   a pressure chamber for holding the pressure introduced therein through the pressure introduction pipe;   a movable member which forms part of the pressure chamber and can be displaced with the pressure changes;   an elastic member placed in a compressed state in the pressure chamber; and   a rod connected to the movable member and can be moved in association with displacement of the movable member.   
   
   
       12 . The exhaust pressure control valve according to  claim 11 , further comprising a ling member,
 wherein   the bypass valve includes a valve element and an arm attached to the valve element,   the arm is fixed to the link member rotatably coupled to the bypass valve opening/closing device, and   the valve opening pressure changing device is adapted to change the valve opening pressure of the bypass valve by moving the rod into or out of contact with the link member.   
   
   
       13 . The exhaust pressure control valve according to  claim 11 , further comprising:
 a ling member; and   a power drive element in the bypass valve opening/closing device,   wherein   the bypass valve includes a valve element and an arm attached to the valve element,   the arm is fixed to one end of the link member and the other end of the link member is rotatably coupled to the bypass valve opening/closing device, and   the valve opening pressure changing device is placed on the same side as the bypass valve opening/closing device relative to the link member and in series with the bypass valve opening/closing device so that the rod is moved into or out of contact with the power drive element.   
   
   
       14 . The exhaust pressure control valve according to  claim 12 , wherein
 the arm is attached to one end of the link member and the bypass valve opening/closing device is coupled to the other end of the link member, and   the valve opening pressure changing device is placed on an opposite side to the bypass valve opening/closing device relative to the link member and arranged so that the rod is moved into or out of contact with a connection part between the link member and the bypass valve opening/closing device.   
   
   
       15 . The exhaust pressure control valve according to  claim 12 , wherein
 the arm is attached to one end of the link member,   the valve opening pressure changing device is placed on the same side as the bypass valve opening/closing device relative to the link member and arranged so that the rod is moved into or out of contact with the other end of the link member, and   the bypass valve opening/closing device is coupled to the link member between a portion fixed to the arm and a portion contacting with the rod.   
   
   
       16 . The exhaust pressure control valve according to  claim 12 , wherein
 the bypass valve opening/closing device is coupled to one end of the link member,   the valve opening pressure changing device is placed on the same side as the bypass valve opening/closing device relative to the link member and arranged so that the rod is moved into or out of contact with the other end of the link member, and   the arm is fixed to the link member between a portion connected with the bypass valve opening/closing device and a portion contacting with the rod.   
   
   
       17 . The exhaust pressure control valve according to  claim 12 , wherein
 the bypass valve opening/closing device is coupled to one end of the link member,   the valve opening pressure changing device is placed on an opposite side to the bypass valve opening/closing device relative to the link member and arranged so that the rod is moved into or out of contact with the other end of the link member, and   the arm is fixed to the link member between a portion connected with the bypass valve opening/closing device and a portion contacting with the rod.   
   
   
       18 . An exhaust pressure control apparatus comprising:
 an exhaust pressure control valve set forth in  claim 1 ; and   a diesel particulate filter (DPF) device to be mounted in an exhaust gas passage of an internal combustion engine for purifying exhaust gas discharged from the engine,   wherein the DPF device is placed upstream of the exhaust pressure control valve.