Abstract: An intake manifold has a plurality of branch tubes each joined by brazing in a furnace at one end to a flange on the engine side and at the other end to a surge tank on the throttle chamber side. The surge tank is separated into two pieces or a brazing side member and a non-heating side member. Branch tubes are fixed in position relative to the brazing side member by peen locking with a peening tool or the like and are then joined to the brazing side member by brazing in the furnace. The non-heating side member is not subjected to the brazing in the furnace but is joined to the brazing side member by bolts or the like.

Abstract: A method of securing intake tubes in an intake manifold is provided in which leakage of brazing material from the joint between the intake tubes and the intake tube mounting rings is prevented. For securing each intake tube in the intake manifold, the intake tube 3 is fitted into the intake tube mounting ring 5. Then, a jig 13 of a tubular shape is inserted into insert areas of the intake tube 3 and the intake tube mounting ring 5. The jig 13 includes separate sections 16 defined by slits extending to a predetermined length in parallel to the axis and has a plurality of projections 19 and 20 provided on the outer side of the separate sections 16 thereof. A bar-like pressing tool 14 reduced in the diameter towards its front end is inserted into the interior of a tubular shape of the peen locking jig 13, and it is then advanced relatively towards the insert area by the action of pressing means.

Abstract: A surge tank structure in an intake manifold has a serge tank to which a plurality of branch tubes are joined at one end. The branch tubes are joined at the other end to a cylinder head mounting flange, and one end of each branch tube in the surge tank is enlarged to have a horn-like shape. The serge tank comprises a main body and a top plate. The main body has through holes provided therein for accepting the branch tubes and has its top side opened. The top plate is joined in a plane to the top of the main body. The main body has a bottom which has engagement recesses formed by raised portions, so that each engagement recess has a horn-like surface that conforms to the horn-like shape of one end of each branch tube.

Abstract: An intake manifold is provided in which blow-by gas is distributed uniformly and readily to the cylinders of an engine. The intake manifold 10 is made of aluminum and has a blow-by gas passage 14 formed integral with a collector 11 as ridged on the collector 11 and located adjacent to the proximal ends of intake manifolds 12a,12b, 12c, and 12d, which are mounted vertically of the collector 11, to extend at a right angle to the axes of the intake manifolds 12. Mounting rings 20 are provided next to the ridged block-by gas passage 14 for accepting the proximal ends of the intake tubes 12.