Internal combustion engine

Patent metadata

Field	Value
Publication number	US-10145274-B2
Application number	US-201715474303-A
Country	US
Kind code	B2
Filing date	Mar 30, 2017
Priority date	Mar 31, 2016
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

An internal combustion engine is provided with a DOHC-type valve train in a cylinder head. The valve train includes an intake side camshaft with an intake side driven gear, and an exhaust side camshaft with an exhaust side driven gear. The cylinder head supports therein a spindle with an idle gear with an idle chain sprocket fixed thereto. The idle gear is in meshing engagement with both the intake and exhaust side driven gears. Rotary power of a crankshaft is transmitted via a cam chain to the idle gear to rotate both the intake and exhaust side camshafts. These camshafts are supported by bearings of a bearing wall and a camshaft holder. These bearings and camshaft holder are located, for compact arrangement, at a position axially coinciding or overlapping with the idle chain sprocket.

First claim

The invention claimed is:

1. An internal combustion engine, comprising:
a cylinder head fixedly fastened on a cylinder block;
a crankshaft rotatable by a piston in the cylinder block;
a DOHC-type valve train provided in the cylinder head and including a rotatable intake side camshaft and a rotatable exhaust side camshaft in parallel arrangement;
a bearing wall with bearings for rotatably supporting the intake side camshaft and the exhaust side camshaft, respectively;
a camshaft holder for holding the intake side camshaft and the exhaust side camshaft supported by the bearings;
an intake side driven gear and an exhaust side driven gear fixedly fitted on ends of the intake side camshaft and the exhaust side camshaft, respectively, the ends of the intake and exhaust side camshafts extending beyond the bearing wall ( 3 U) and the camshaft holder;
an idle gear fixedly supported on a spindle supported in the cylinder head to mesh with both the intake and exhaust side driven gears;
an idle chain sprocket coaxially fixed to the idle gear at an axial position adjacent to the bearing wall; and
a cam chain passed around a driving chain sprocket on the crankshaft and the idle chain sprocket in such a manner that rotational power of the crankshaft is transmitted to the intake and exhaust side camshafts; characterized in that:
the idle chain sprocket is positioned at an axial position coinciding or overlapping with axial positions of the bearings of the bearing wall and the camshaft holder, with respect to an axial direction parallel to the intake and exhaust side camshaft.

2. The internal combustion engine according to claim 1 , wherein:
the camshaft holder is fastened to the bearing wall to cover the bearings by fastening bolts, at the same axial position as the idle chain sprocket, to rotatably support the intake and exhaust side camshafts; and
out of the fastening bolts, some fastening bolts arranged at ends of the camshaft holder, with respect to a direction transverse to the axial direction, fasten portions of the camshaft holder on both sides of the idle chain sprocket.

3. The internal combustion engine according to claim 2 , wherein:
the bearing wall and the camshaft holder have protruding portions extending axially inward of the bearing wall and the camshaft holder and located between the intake side camshaft and the exhaust side camshaft; and
out of the fastening bolts, at least one fastening bolt fastens a part of the camshaft holder, in the protruding portions.

4. The internal combustion engine according to claim 3 , comprising:
a cylindrical intake side cam carrier fitted on and around the intake side camshaft in a manner co-rotatable with, and axially slidable relative to the intake side camshaft, and having a plurality of cam lobes different in cam profile and axially adjacent to each other, the intake side cam carrier having a lead groove cylindrical portion including a lead groove for fitting engagement with a changeover pin;
a cylindrical exhaust side cam carrier fitted on and around the exhaust side camshaft in a manner co-rotatable with, and axially slidable relative to the exhaust side camshaft, and having a plurality of cam lobes different in cam profile and axially adjacent to each other, the exhaust side cam carrier having a lead groove cylindrical portion including a lead groove for fitting engagement with a changeover pin; and
cam changeover mechanisms for advancing and retracting the changeover pin into engagement with and disengagement from the lead groove to axially shift the intake side cam carrier and the exhaust side cam carrier so as to change over the cams lobes;
wherein the lead groove cylindrical portions including the lead grooves have an outer diameter smaller than an outer diameter of base circle of the cam lobes; and
the protruding portions are located in the same axial area as one lead groove cylindrical portion of at least one of the intake side cam carrier and the exhaust side cam carrier.

Assignees

• Honda Motor Co Ltd

Inventors

• Kataoka Dai
• Takada Yoshihiro

Classifications

• F01L2013/0052

  with cams provided on an axially slidable sleeve · CPC title

• F01L2001/0475

  Hollow camshafts · CPC title

• F01L13/0036

  the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction · CPC title

• F01L1/185

  Overhead end-pivot rocking arms · CPC title

• F01L1/026 Primary

  Gear drive · CPC title