Cylinder bore wall thermal insulator, internal combustion engine, and automobile

A thermal insulator for a cylinder bore wall set in a groove-like coolant passage of a cylinder block of an internal combustion engine including cylinder bores and for insulating all of bore walls in a circumferential direction of all the cylinder bores or a part of the bore walls in the circumferential direction of all the cylinder bores when viewed in the circumferential direction, the thermal insulator comprising:

• bore wall insulating sections having an arcuate shape when viewed from above and for insulating a wall surface on the cylinder bore side of the groove-like coolant passage;
• and
• a supporting section having a shape conforming to a shape of the groove-like coolant passage in a setting position of the thermal insulator, the bore wall insulating sections being fixed to the supporting section only in a center or a vicinity of the center in an arc direction of each of the bore wall insulating sections, wherein
• each of the bore wall insulating sections includes:
• a rubber member in contact with the wall surface on the cylinder bore side of the groove-like coolant passage and for covering the wall surface on the cylinder bore side of the groove-like coolant passage;
• a rear surface pressing member provided on a rear surface side of the rubber member and for pressing the entire rubber member toward the wall surface on the cylinder bore side of the groove-like coolant passage from the rear surface side;
• and elastic members that urge the rear surface pressing member to press the rubber member toward the wall surface on the cylinder bore side of the groove-like coolant passage,
• an opening in each of supporting section bore portions to which the respective bore wall insulating sections are to be fixed, the opening being through which the elastic member passes from an inner side to the rear surface side of the supporting section,
• a coolant passage opening through which coolant flowing on the rear surface side of the supporting section passes to flow to an inner side of the supporting section is formed on at least one place of upper portions of supporting section inter-bore portions, and
• the supporting section has a guide wall for guiding the coolant formed in a vicinity of the coolant passage opening, such that the coolant flows into the coolant passage opening, and a coolant gathering wall extending with an upward inclination toward the guide wall.

A thermal insulator for a cylinder bore wall set in the groove-like coolant passage of a cylinder block of an internal combustion engine including cylinder bores and for insulating all of bore walls in a circumferential direction of all the cylinder bores when viewed in the circumferential direction, the thermal insulator comprising:

• bore wall insulating sections having an arcuate shape when viewed from above and for insulating a wall surface on the cylinder bore side of the groove-like coolant passage;
• and
• a supporting section having a shape conforming to a shape of the groove-like coolant passage in a setting position of the thermal insulator, the bore wall insulating sections being fixed to the supporting section only in a center or a vicinity of the center in an arc direction of each of the bore wall insulating sections, wherein
• each of the bore wall insulating sections includes:
• a rubber member in contact with the wall surface on the cylinder bore side of the groove-like coolant passage and for covering the wall surface on the cylinder bore side of the groove-like coolant passage;
• a rear surface pressing member provided on a rear surface side of the rubber member and for pressing the entire rubber member toward the wall surface on the cylinder bore side of the groove-like coolant passage from the rear surface side;
• and elastic members that urge the rear surface pressing member to press the rubber member toward the wall surface on the cylinder bore side of the groove-like coolant passage,
• an opening in each of supporting section bore portions to which the respective bore wall insulating sections are to be fixed, the opening being through which the elastic member passes from an inner side to the rear surface side of the supporting section,
• a coolant passage opening through which coolant flowing on the rear surface side of the supporting section passes to flow to an inner side of the supporting section is formed on at least one place of upper portions of supporting section inter-bore portions set in the groove-like coolant passage in one-side half in which the coolant flows more vigorously,
• the supporting section set in the groove-like coolant passage in the one-side half in which the coolant flows more vigorously has a guide wall for guiding the coolant formed in a vicinity of the coolant passage opening, such that the coolant flows into the coolant passage opening, and has an inclined wall formed on the rear surface side of the supporting section at a position where the coolant is supplied into the groove-like coolant passage, the inclined wall extending with an upward inclination to create a flow of the coolant toward the coolant passage opening,
• a coolant passage opening through which coolant flowing on the rear surface side of the supporting section passes to flow to an inner side of the supporting section is formed on at least one place of upper portions of supporting section inter-bore portions set in the groove-like coolant passage in one-side half on an opposite side of the one-side half in which the coolant flows more vigorously, and
• the supporting section set in the groove-like coolant passage in the one-side half on the opposite side of the one-side half in which the coolant flows more vigorously has a guide wall for guiding the coolant formed in a vicinity of the coolant passage opening, such that the coolant flows into the coolant passage opening, and has a coolant gathering wall extending with an upward inclination toward the guide wall.