Compression ratio variable device in internal combustion engine

A compression ratio changing device in an internal combustion engine, comprising:

• a piston inner element connected to a connecting rod through a piston pin,
• a piston outer element which is fitted over an outer periphery of said piston inner element for sliding movement only in an axial direction with respect to the piston inner element, with an outer end face of the piston outer element exposed to a combustion chamber, said piston outer element capable of being moved between a lower-compression ratio position (L) close to said piston inner element and a higher-compression ratio position (H) close to said combustion chamber,
• a bulking member interposed between said piston inner and outer elements and capable of being moved between a non-bulking position (A) where said bulking member permits the movement of said piston outer element to the lower-compression ratio position (L), and a bulking position (B) where said piston outer element is retained in the higher-compression ratio position, and
• an actuator for operating said bulking member alternately in the non-bulking position (A) and the bulking position (B),
• wherein said actuator comprises an operating member and a returning member which are slidably disposed in said piston inner element on the same axis extending in a direction of turning of said bulking member and are opposed to each other on opposite sides of a pressure-receiving portion of said bulking member, so that said bulking member is turned alternately to the non-bulking position (A) and the bulking position (B) by alternately operating said operating member and said returning member,
• wherein said operating member and said returning member comprise an operating plunger and a returning plunger, respectively, which are slidably received in a common cylinder bore defined in said piston inner element and are opposed to each other on opposite sides of said pressure-receiving portion.

A compression ratio changing device in an internal combustion engine, comprising:

• a piston inner element connected to a connecting rod through a piston pin, a piston outer element which is fitted over an outer periphery of said piston inner element for sliding movement only in an axial direction with respect to the piston inner element, with an outer end face of the piston outer element exposed to a combustion chamber, said piston outer element capable of being moved between a lower-compression ratio position (L) close to said piston inner element and a higher-compression ratio position (H) close to said combustion chamber,
• a bulking member interposed between said piston inner and outer elements and capable of being moved between a non-bulking position (A) where said bulking member permits the movement of said piston outer element to the lower-compression ratio position (L), and a bulking position (B) where said piston outer element is retained in the higher-compression ratio position, and
• an actuator for operating said bulking member alternately in the non-bulking position (A) and the bulking position (B),
• wherein said actuator comprises an operating member and a returning member which are slidably disposed in said piston inner element on the same axis extending in a direction of turning of said bulking member and are opposed to each other on opposite sides of a pressure-receiving portion of said bulking member, so that said bulking member is turned alternately to the non-bulking position (A) and the bulking position (B) by alternately operating said operating member and said returning member, and
• wherein said actuators are disposed in a plurality of sets at equal distances in a circumferential direction of said bulking member.

A compression ratio changing device in an internal combustion engine, comprising a piston inner element connected to a connecting rod through a piston pin, a piston outer element which is fitted over an outer periphery of said piston inner element for sliding movement only in an axial direction with respect to the piston inner element, with an outer end face of the piston outer element exposed to a combustion chamber, said piston outer element capable of being moved between a lower-compression ratio position (L) close to said piston inner element and a higher-compression ratio position (H) close to said combustion chamber, a bulking member interposed between said piston inner and outer elements and capable of being moved between a non-bulking position (A) where said bulking member permits the movement of said piston outer element to the lower-compression ratio position (L), and a bulking position (B) where said piston outer element is retained in the higher-compression ratio position (H), and an actuator for operating said bulking member alternately in the non-bulking position (A) and the bulking position (B),

• wherein a cam mechanism is provided between axially opposed surfaces of the bulking member and one of said piston inner and outer elements said cam mechanism comprising a first cam structure provided on said bulking member and having first projections and first recesses, and a second cam structure provided on said one of the piston inner and outer elements and having second projections and second recesses, said first projections projecting toward said one of the piston inner and outer elements in the axial direction, said second projections projecting toward said bulking member in the axial direction, and
• wherein at said non-bulking position (A) top faces of the first and second projections are placed in abutment against root faces of the recesses of the opponent cam structures, respectively, in the axial direction, whereas at said bulking position (B) the top faces of the first and second projections of the first and second cam structures are placed in abutment against each other, so that at least a load acting in the axial direction from the piston outer element to the piston inner element during operation of the engine is received by the abutment between the first and second cam structures.

A compression ratio changing device in an internal combustion engine, comprising a piston inner element connected to a connecting rod through a piston pin, a piston outer element which is fitted over an outer periphery of said piston inner element for sliding movement only in an axial direction with respect to the piston inner element, with an outer end face of the piston outer element exposed to a combustion chamber, said piston outer element capable of being moved between a lower compression ratio position (L) close to said piston inner element and a higher-compression ratio position (H) close to said combustion chamber, a bulking member interposed between said piston inner and outer elements and provided on one of said piston inner and outer elements so as to be rotatable relative to said one of the piston inner and outer elements in a circumferential direction around the piston axis between a non-bulking position (A) where said bulking member permits the movement of said piston outer element to the lower-compression ratio position (L), and a bulking position (B) where said piston outer element is retained in the higher-compression ratio position (H), and an actuator for operating said bulking member alternately in the non-bulking position (A) and the bulking position (B),

• wherein a device is provided for changing relative axial positions of said piston inner and outer elements with respect to each other in response to a relative rotation of the bulking member with respect to said one of the piston inner and outer elements in the circumferential direction.