Variable compression ratio internal combustion engine

Patent metadata

Field	Value
Publication number	US-9850813-B2
Application number	US-201415325098-A
Country	US
Kind code	B2
Filing date	Jul 14, 2014
Priority date	Jul 14, 2014
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

A variable compression ratio internal combustion engine includes a control shaft rotatably supported by an engine body, a variable compression ratio mechanism, an actuator for driving the control shaft, and a speed reducing mechanism for reducing a rotational power of the actuator and for transmitting the speed-reduced power to the control shaft, and structured to have a rotation shaft rotatably supported in a housing fixed to the engine body and a lever that connects the rotation shaft and the control shaft. Located in the engine body is a first regulation part for mechanically regulating the control shaft to a position of maximum rotation on a high compression ratio side. Also located in the housing is a second regulation part for mechanically regulating the rotation shaft to a position of maximum rotation on a low compression ratio side.

First claim

The invention claimed is:

1. A variable compression ratio internal combustion engine including a control shaft rotatably supported by an engine body, a variable compression ratio mechanism for changing an engine compression ratio in accordance with a rotational position of the control shaft, an actuator that rotatively drives the control shaft, and a speed reducing mechanism for reducing a rotational power of the actuator and for transmitting the speed-reduced power to the control shaft, the speed reducing mechanism having a rotation shaft rotatably supported in a housing fixed to the engine body and a lever that connects the rotation shaft and the control shaft, comprising:
a first regulation part located in the engine body for mechanically regulating the control shaft to a position of maximum rotation on one side of a low compression ratio side and a high compression ratio side; and
a second regulation part located in the housing for mechanically regulating the rotation shaft to a position of maximum rotation on the other side of the low compression ratio side and the high compression ratio side.

2. A variable compression ratio internal combustion engine as recited in claim 1 , wherein:
the first regulation part is configured to regulate the control shaft to the position of maximum rotation on the high compression ratio side; and
the second regulation part is configured to regulate the rotation shaft to the position of maximum rotation on the low compression ratio side.

3. A variable compression ratio internal combustion engine as recited in claim 1 , which further comprises:
a rotation sensor for detecting a rotational position of one shaft of the control shaft and the rotation shaft; and
a reference position learning means for carrying out compression ratio reference position learning operation, based on a detection signal from the rotation sensor, in a state where the other shaft of the control shaft and the rotation shaft has been mechanically regulated by either the first regulation part or the second regulation part.

4. A variable compression ratio internal combustion engine as recited in claim 3 , wherein:
the rotation sensor is configured to detect the rotational position of the rotation shaft; and
the reference position learning means is configured to carry out the compression ratio reference position learning operation, based on the detection signal from the rotation sensor, in a state where the control shaft has been mechanically regulated by the first regulation part.

5. A variable compression ratio internal combustion engine as recited in claim 1 , wherein:
the rotation shaft is set so that the rotation shaft is positioned within a predetermined angular range containing a rotational position such that torque about the rotation shaft, which torque is transmitted from the control shaft through the lever to the rotation shaft, becomes a minimum in a state where the rotation shaft has been mechanically regulated by the second regulation part.

6. A variable compression ratio internal combustion engine as recited in claim 1 , wherein:
the first regulation part has a high compression ratio side stopper face on which a part of the control shaft abuts when the control shaft has been rotated to the position of maximum rotation on the high compression ratio side;
the second regulation part has a low compression ratio side stopper face on which a part of the rotation shaft abuts when the rotation shaft has been rotated to the position of maximum rotation on the low compression ratio side; and
a surface accuracy of the high compression ratio side stopper face is set higher than a surface accuracy of the low compression ratio side stopper face.

7. A variable compression ratio internal combustion engine as recited in claim 1 , wherein:
the variable compression ratio mechanism comprises:
a lower link rotatably installed on a crankpin of a crankshaft;
an upper link that connects the lower link and a piston of the internal combustion engine; and
a control link that connects the control shaft and the lower link.

Assignees

• Nissan Motor

Inventors

• Hiyoshi Ryosuke
• Tanaka Yoshiaki

Classifications

• F02D15/02

  by alteration or displacement of piston stroke · CPC title

• F02B75/045 Primary

  by means of a variable connecting rod length · CPC title

• F02B75/04

  Engines with variable distances between pistons at top dead-centre positions and cylinder heads · CPC title

• F02B75/32

  Engines characterised by connections between pistons and main shafts and not specific to preceding main groups · CPC title