Internal combustion engine

Patent metadata

Field	Value
Publication number	US-10508718-B2
Application number	US-201715704953-A
Country	US
Kind code	B2
Filing date	Sep 14, 2017
Priority date	Sep 30, 2016
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

In an internal combustion engine including a driving-sprocket cam chain guide 70 for guiding a cam chain 47 along a driving sprocket 45 , as viewed in a crankshaft axial direction, a guide body 71 of the driving-sprocket cam chain guide 70 extends beyond a winding termination point P of the cam chain 47 on the driving sprocket 45 to a position adjacent to a chain moving surface 51 c of a cam chain tensioner 51 , on which the cam chain 47 slides. The engine provides a cam-chain dropout preventing function to the cam chain guide, thus reducing load on the cam chain tensioner and improving durability of the tensioner lifter.

First claim

The invention claimed is:

1. An internal combustion engine comprising:
a driving sprocket ( 45 ) integrally rotatable with a crankshaft ( 20 );
a driven sprocket ( 46 ) integrally rotatable with a camshaft ( 41 ) driving a valve train ( 40 );
a cam chain ( 47 ) wound between the driving sprocket ( 45 ) and the driven sprocket ( 46 ) and transferring power of the crankshaft ( 20 ) to the camshaft ( 41 );
a cam chain tensioner ( 51 ) for pressing the cam chain ( 47 ) at a position between the driving sprocket ( 45 ) and the driven sprocket ( 46 );
a tensioner lifter ( 60 ) for pressing the cam chain tensioner ( 51 ) with a predetermined pressure; and
a driving-sprocket cam chain guide ( 70 ) for guiding the cam chain ( 47 ) along the driving sprocket ( 45 );
wherein, as viewed in a crankshaft axial direction, the driving-sprocket cam chain guide ( 70 ) includes a guide body ( 71 ) extending beyond a winding termination point (P) of the cam chain ( 47 ) on the driving sprocket ( 45 ) to a position adjoining a chain moving surface ( 52 a ) of the cam chain tensioner ( 51 ), on which the cam chain ( 47 ) slides.

2. The internal combustion engine according to claim 1 ,
wherein the internal combustion engine (E) includes a crankcase ( 1 ) for bearing the crankshaft ( 20 ),
the crankcase ( 1 ) includes a cam-chain tensioner support portion ( 1 b ) for swingably supporting the cam chain tensioner ( 51 ),
the crankcase ( 1 ) includes a driving-sprocket cam chain guide fixing portion ( 1 c ), which is independent from the cam-chain tensioner support portion ( 1 b ) and fixes the driving-sprocket cam chain guide ( 70 ), and
the cam-chain tensioner support portion ( 1 b ) is located nearer to the camshaft ( 41 ) than a camshaft side end ( 45 a ) of the driving sprocket ( 45 ).

3. The internal combustion engine according to claim 2 , wherein the driving-sprocket cam chain guide fixing portion ( 1 c ) is located adjacent to the cam-chain tensioner support portion ( 1 b ) in a moving direction of the cam chain ( 47 ).

4. The internal combustion engine according to claim 3 , wherein the driving-sprocket cam chain guide ( 70 ) is made of a synthetic resin while the guide body ( 71 ) has a J-shaped configuration to guide at least a lower end ( 47 a ) of the cam chain ( 47 ) from below.

5. The internal combustion engine according to claim 4 , wherein the driving-sprocket cam chain guide ( 70 ) includes an overhang portion ( 70 a ) which, as viewed in the axial direction of the crankshaft ( 20 ), extends to an end part ( 71 b ) thereof in a direction making an overhang angle to a line (L 2 ), which is Parallel to a line (L 1 ) connecting a rotational center (C 1 ) of the driving sprocket ( 45 ) and a rotational center (C 2 ) of the driven sprocket ( 46 ) and which is tangent to the winding termination point (P) of the cam chain ( 47 ) on the driving sprocket ( 45 ), in such a manner that the cam chain ( 47 ) is caused to be directed inward.

6. The internal combustion engine according to claim 5 , wherein
the internal combustion engine includes a cylinder body ( 2 ) and a cylinder head ( 3 ) which are sequentially stacked on the crankcase ( 1 ), and
the tensioner lifter ( 60 ) is disposed on the cylinder head ( 3 ).

7. The internal combustion engine according to claim 6 , wherein the tensioner lifter ( 60 ) includes a pressing member ( 62 ) for pressing the cam chain tensioner ( 51 ), the pressing member ( 62 ) having an axis (Lt) of sliding direction, the axis (Lt) being inclined upward relative to a mating surface (P 1 ) between the cylinder body ( 2 ) and the cylinder head ( 3 ).

8. The internal combustion engine according to claim 7 , wherein the cam chain tensioner ( 51 ) has a tensioner-lifter-abutting-side half ( 51 a ) pressed by the pressing member ( 62 ), and a fixing-portion-side half ( 51 b ), the tensioner-lifter-abutting-side half ( 51 a ) being larger than the fixing-portion-side half ( 51 b ).

Assignees

• Honda Motor Co Ltd

Inventors

• Ikeda Tsugio
• Hara Shigeyuki
• Narushima Masaji
• Tsutsumi Koichi
• Takeichi Hiroto

Classifications

• F01L1/026

  Gear drive · CPC title

• F01L2301/00

  Using particular materials · CPC title

• F01L2001/0476

  Camshaft bearings · CPC title

• F01L2001/0475

  Hollow camshafts · CPC title

• F01L2001/0537

  Double overhead camshafts [DOHC] · CPC title