Exhaust Manifold

Abstract

In an exhaust manifold, a plurality of branch pipes is bent downward from a head flange to form like an L-letter shape, where exhaust-gas upstream side end portions of the pipes are connected with an engine through the head flange and exhaust-gas downstream side end portions thereof are connected with a pipe collecting part which is provided with a sensor for detecting a state of exhaust gas. The pipe collecting part has a reduced diameter portion where a length of the pipe collecting part in a longitudinal direction of the head flange is set shorter than that of the pipe collecting part in a thickness direction of the head flange. The sensor is provided on the reduced diameter portion.

1 . An exhaust manifold comprising:
 a head flange fixed to an engine;   a plurality of branch pipes which is bent downward from the head flange to form like an L-letter shape, the branch pipes having exhaust-gas upstream side end portions and exhaust-gas downstream side end portions where the exhaust-gas upstream side end portions are connected with the engine through the head flange; and   a pipe collecting part connected with the exhaust-gas downstream side end portions of the branch pipes, the pipe collecting part being provided with a sensor for detecting a state of an exhaust gas, wherein   the pipe collecting part has a reduced diameter portion in which a length, of the pipe collecting part, in a longitudinal direction of the head flange is set to be shorter than a length, of the pipe collecting part, in a thickness direction of the head flange, the reduced diameter portion being provided with the sensor.   
   
   
       2 . The exhaust manifold according to  claim 1 , wherein
 the pipe collecting part has an intermediate portion in which the both surfaces seen from the thickness direction are formed to have an involute curve.   
   
   
       3 . The exhaust manifold according to  claim 3 , wherein
 the pipe collecting part is formed to have curves at both sides, respectively, so that width lengths of the surfaces seen from the thickness direction become larger from an exhaust-gas upstream side end portion of the pipe collecting part to an exhaust-gas downstream side end portion thereof.   
   
   
       4 . The exhaust manifold according to  claim 3 , wherein
 the pipe collecting part has two divided bodies, which are separatable in the longitudinal direction along the thickness direction, coupled with each other.   
   
   
       5 . The exhaust manifold according to  claim 5 , wherein
 the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.   
   
   
       6 . The exhaust manifold according to  claim 2 , wherein
 the pipe collecting part has two divided bodies, which are separatable in the longitudinal direction along the thickness direction, coupled with each other.   
   
   
       7 . The exhaust manifold according to  claim 6 , wherein
 the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.   
   
   
       8 . The exhaust manifold according to  claim 2 , wherein
 the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.   
   
   
       9 . The exhaust manifold according to  claim 1 , wherein
 the pipe collecting part is formed to have curves at both sides, respectively, so that width lengths of the surfaces seen from the thickness direction become larger from an exhaust-gas upstream side end portion of the pipe collecting part to an exhaust-gas downstream side end portion thereof.   
   
   
       10 . The exhaust manifold according to  claim 9 , wherein
 the pipe collecting part has two divided bodies, which are separatable in the longitudinal direction along the thickness direction, coupled with each other.   
   
   
       11 . The exhaust manifold according to  claim 10 , wherein
 the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.   
   
   
       12 . The exhaust manifold according to  claim 9 , wherein
 the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.   
   
   
       13 . The exhaust manifold according to  claim 1 , wherein
 the pipe collecting part has two divided bodies, which are separatable in the longitudinal direction along the thickness direction, coupled with each other.   
   
   
       14 . The exhaust manifold according to  claim 13 , wherein
 the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.   
   
   
       14 . The exhaust manifold according to  claim 1 , wherein
 the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.