Heat-insulating engine structure

Claim 2

A heat-insulating engine structure comprising: a piston reciprocatingly movable in a cylinder liner said piston having a piston skirt portion, a piston head portion fixed to said piston skirt portion, a heat insulating material provided on the upper surface of said piston head portion, and a surface portion provided on the upper surface of said heat insulation material and exposed to combustion gases; said surface portion consisting of a wholly flat, thin ceramic plate portion; a cylinder head bottom wall portion which is made of a ceramics material is, integral with said cylinder liner upper portion, and extends upwardly from its center to periphery so as to have a raised outer peripheral portion all over the circumference of said portion and a lowered central portion; a cylinder head including a tubular section accommodating said integral cylinder liner upper portion and said cylinder head bottom wall portion; said cylinder head bottom wall portion and said cylinder liner upper portion cooperating to define a combustion chamber; a fuel injection nozzle disposed substantially centrally of said cylinder head bottom wall portion and having radially outwardly directed injection orifices; intake and exhaust valve seats formed in an inclined surface of said cylinder head bottom wall portion, said inclined surface extending radially upwardly from said central portion of said cylinder head bottom wall portion to said outer peripheral portion thereof; and intake and exhaust valves associated with said intake and exhaust valve seats, respectively.

Claim 3

A heat-insulating engine structure comprising: a piston reciprocatingly movable in a cylinder liner and having a thin-walled portion whose surface is planar and exposed to combustion gases: a cylinder liner upper portion of ceramics material disposed above said cylinder liner; a cylinder head bottom wall portion which is made of a ceramics material is, integral with said cylinder liner upper portion, and extends upwardly from its center to periphery so as to have a raised outer peripheral portion all over the circumference of said portion and a lowered central portion; a cylinder head including a tubular section accommodating said integral cylinder liner upper portion and said cylinder head bottom wall portion; said cylinder liner upper portion has a tubular upper part of substantially square cross-section and a substantially cylindrical lower part, said cylinder head bottom wall portion and said cylinder liner upper portion cooperating to define a combustion chamber; said combustion chamber including a substantially square portion defined by said tubular upper part of said cylinder liner upper portion; a fuel injection nozzle disposed substantially centrally of said cylinder head bottom wall portion and having radially outwardly directed injection orifices; intake and exhaust valve seats formed in an inclined surface of said cylinder head bottom wall portion, said inclined surface extending radially upwardly from said central portion of said cylinder head bottom wall portion to said outer peripheral portion thereof; and intake and exhaust valves associated with said intake and exhaust valve seats, respectively.

Claim 4

A heat-insulating engine structure comprising: a piston reciprocatingly movable in a cylinder liner and having a thin-walled portion whose surface is planar and exposed to combustion gases: a cylinder liner upper portion of ceramics material disposed above said cylinder liner; a cylinder head bottom wall portion which is made of a ceramics material is, integral with said cylinder liner upper portion, and extends upwardly from its center to periphery so as to have a raised outer peripheral portion all over the circumference of said portion and a lowered central portion; a cylinder head including a tubular section accommodating said integral cylinder liner upper portion and said cylinder head bottom wall portion; said cylinder liner upper portion has a tubular upper part of substantially square cross-section and a substantially cylindrical lower part, said cylinder head bottom wall portion and said cylinder liner upper portion cooperating to define a combustion chamber; said combustion chamber including a substantially square portion defined by said tubular upper part of said cylinder liner upper portion; a fuel injection nozzle disposed substantially centrally of said cylinder head bottom wall portion and having radially outwardly directed injection orifices; intake and exhaust valve seats formed in an inclined surface of said cylinder head bottom wall portion, said inclined surface extending radially upwardly from said central portion of said cylinder head bottom wall portion to said outer peripheral portion thereof; and intake and exhaust valves associated with said intake and exhaust valve seats, respectively.

Claim 5

A heat-insulating engine structure according to claim 2, wherein said tubular upper part of substantially square cross-section is smaller than the inner diameter of said cylindrical lower part.

Claim 6

A heat-insulating engine structure according to claim 2, wherein said tubular upper part has rounded corners.

Claim 7

A heat-insulating engine structure according to claim 1, wherein said fuel injection nozzle injects a fuel radially outwardly through said injection orifices into said combustion chamber.

Claim 8

A heat-insulating engine structure according to claim 1, wherein said cylinder head bottom wall portion and said cylinder liner upper portion are of an integral thin-walled structure of a ceramics material.

Claim 9

A heat-insulating engine structure according to claim 1, wherein said cylinder head bottom wall portion and said cylinder liner upper portion are of an integral structure of silicon nitride.

Claim 10

A heat-insulating engine structure according to claim 1, wherein said cylinder head bottom wall portion and said cylinder liner upper portion are of an integral structure of silicon carbide.

Claim 11

A heat-insulating engine structure according to claim 1, wherein a heat-insulating layer is disposed between said cylinder head bottom wall portion and said cylinder and between an outer peripheral surface of said cylinder liner upper portion and an inner peripheral surface of said cylinder head.

Claim 12

A heat-insulating engine structure according to claim 8, wherein said heat-insulating layer includes a heat-insulating material made of potassium titanate and the like.

Claim 13

A heat-insulating engine structure according to claim 1, wherein said intake and exhaust valves are disposed in a generally inverted V arrangement.

Claim 14

A heat-insulating engine structure according to claim 10, wherein said cylinder head is formed therein with an intake port extending obliquely and radially inwardly to said intake valve seat.

Claim 15

A heat-insulating engine structure according to claim 11, wherein intake air introduced through said intake port into said combustion chamber in each suction stroke of the engine includes a primary flow disposed substantially vertically centrally of said combustion chamber.

Claim 16

A heat-insulating engine structure according to claim 13, wherein sprays of fuel injected into said combustion chamber and intake air form a swirl and wherein said tubular upper part of substantially square cross-section has sides operative to agitate said swirl whereby the fuel and the air are immediately and uniformly mixed.

Claim 17

A heat-insulating engine structure according to claim 1, wherein said piston includes a piston skirt having an upper end wall, a piston head portion having a mounting portion by which said piston head portion is mounted on said upper end wall, a ring of a ceramics material urged against and secured to an upper surface of said piston skirt, a thin-walled portion constituting said planar surface and having an outer periphery bonded to said ring, said piston head portion having an undersurface cooperating with an undersurface of said thin-walled portion and with a part of an inner peripheral surface of said ring to define a space, and a heat-insulating material disposed in and filling up said space.

Claim 18

A heat-insulating engine structure according to claim 14, wherein said thin-walled portion constitutes said planar surface to be exposed to combustion gases and is made of a ceramics material having as thin a wall thickness as possible.

Claim 19

A heat-insulating engine structure according to claim 15, wherein the outer periphery of said thin-walled portion is bonded to an upper part of said ring by a chemical vapor deposition of a ceramics material.

Claim 20

A heat-insulating engine structure according to 15, wherein said piston head has a planar upper surface.

Claim 21

A heat-insulating engine structure according to 15, wherein said piston head has a planar upper surface.

Claim 22

A heat-insulating engine structure according to claim 15, wherein said heat-insulating material acts as a structural member which bears a pressure acting on said thin-walled portion.

Claim 23

A heat-insulating engine structure according to claim 15, wherein said thin-walled portion and said ring are made of silicon nitride.

Claim 24

A heat-insulating engine structure according to claim 15, wherein said thin-walled portion and said ring are made of silicon carbide.

Claim 25

A heat-insulating engine structure comprising: a piston reciprocatingly movable in a cylinder liner, said piston having a piston skirt portion, a piston head portion fixed to said piston skirt portion, a heat insulating material provided on the upper surface of said piston head portion, and a surface portion provided on the upper surface of said heat insulating material and adapted to be exposed to combustion gases, said surface portion consisting of an entirely flat and thin ceramic plate portion; a cylinder head bottom wall portion of ceramic material, integral with said cylinder linear upper portion, and extending upwardly from a central part to a periphery thereof so as to have a raised outer peripheral part all over the circumference of said portion and a lowered central part, said cylinder head bottom wall portion and said flat thin ceramic plate portion of said piston defining therebetween a combustion cavity having a cross-sectional height which varies from a minimum adjacent the central part of said cylinder head bottom wall portion to a maximum adjacent the peripheral part of said cylinder head bottom wall portion; a cylinder head including a tubular section accommodating said integral cylinder liner upper portion and said cylinder head bottom wall portion; a fuel injection nozzle disposed substantially centrally of said cylinder head bottom wall portion and having radially outwardly directed injection orifices; intake and exhaust valve seats formed in an inclined surface of said cylinder head bottom wall portion, said inclined surface extending radially upwardly from said central portion of said cylinder head bottom wall portion to said outer peripheral portion thereof; and intake and exhaust valves associated with said intake and exhaust valve seats, respectively.

Claim 26

A heat-insulating engine structure comprising: a piston reciprocatingly movable in a cylinder liner, said piston having a piston skirt portion, a piston head portion fixed to said piston skirt portion, a heat insulating material provided on the upper surface of said piston head portion, and a surface portion provided on the upper surface of said heat insulating material and adapted to be exposed to combustion gases, said surface portion consisting of an entirely flat and thin ceramic plate portion; a cylinder head bottom wall portion of ceramic material, integral with said cylinder linear upper portion, and extending upwardly from a central part to a periphery thereof so as to have a raised outer peripheral part all over the circumference of said portion and a lowered central part, said cylinder head bottom wall portion and said flat thin ceramic plate portion of said piston defining therebetween a combustion cavity having a cross-sectional height which varies from a minimum adjacent the central part of said cylinder head bottom wall portion to a maximum adjacent the peripheral part of said cylinder head bottom wall portion; a cylinder head including a tubular section accommodating said integral cylinder liner upper portion and said cylinder head bottom wall portion; a fuel injection nozzle disposed substantially centrally of said cylinder head bottom wall portion and having radially outwardly directed injection orifices; intake and exhaust valve seats formed in an inclined surface of said cylinder head bottom wall portion, said inclined surface extending radially upwardly from said central portion of said cylinder head bottom wall portion to said outer peripheral portion thereof; and intake and exhaust valves associated with said intake and exhaust valve seats, respectively.