Piston structure with a combustion chamber

• US 5,645,028 A
• Filed: 11/21/1995
• Issued: 07/08/1997
• Est. Priority Date: 11/21/1995
• Status: Expired due to Fees

• Current Assignee: Isuzu Motors Limited
• Original Assignee: Isuzu Motors Limited
• Inventors: Matsuoka, Hiroshi, Kawamura, Hideo
• Primary Examiner(s): MCMAHON, MARGUERITE J
• Application Number:
  US08/561,002
• Time in Patent Office: 595 Days
• Field of Search: 123/276, 123/279, 123/293, 123/273, 123/193.6
• US Class Current: 123/276
• CPC Class Codes: F02B 2023/0609 the material being a porous medium, e.g. sintered metal
• CPC Class Codes: F02B 2023/0612 the material having a high temperature and pressure resistance, e.g. ceramic
• CPC Class Codes: F02B 2275/14 Direct injection into combustion chamber
• CPC Class Codes: F02B 23/0603 at least part of the interior volume or the wall of the combustion space being made of material different from the surrounding piston part, e.g. combustion space formed within a ceramic part fixed to a metal piston head
• CPC Class Codes: F02B 23/0627 having additional bores or grooves machined into the piston for guiding air or charge flow to the piston bowl
• CPC Class Codes: F02B 23/0633 the combustion space being almost completely enclosed in the piston, i.e. having a small inlet in comparison to its volume
• CPC Class Codes: F02B 23/0636 the combustion space having a substantially flat and horizontal bottom
• CPC Class Codes: F02B 23/0675 the combustion space being substantially spherical, hemispherical, ellipsoid or parabolic
• CPC Class Codes: F05C 2201/046 Stainless steel or inox, e.g. 18-8
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

The combustion chamber structure having a combustion chamber almost at the center of the piston is installed in a cavity formed in the piston body with a heat insulating layer interposed therebetween. The combustion chamber structure and the piston body are joined by a joining member. The combustion chamber structure is formed with a nozzle insertion hole and communication holes. The joining member is made of a material with a thermal expansion coefficient intermediate between those of the piston body and the combustion chamber structure, or of almost the same kind of material as the piston body. Alternatively, the combustion chamber structure forms a piston head portion and the piston body forms a piston skirt portion. The lower surface of the piston head portion is formed as a tapered surface that is inclined toward the periphery. The upper surface of the piston skirt portion is also formed as a tapered surface that extends along the opposing tapered surface of the piston head portion. The lower surface of the outer periphery of the piston head portion and the upper surface of the outer periphery of the piston skirt portion are in firm contact with each other. The combustion chamber structure of this invention is so constructed that a rich air-fuel mixture is generated in the upper part of the combustion chamber and that the mixture is quickly ejected into the cylinder chamber to reduce the combustion period.

Claims

1. A piston structure comprising:

a piston body made of a metal material and having a cavity formed at the center of a piston head portion;

a combustion chamber structure made of a heat-resistant, high-temperature high-strength material installed in the cavity, the combustion chamber structure including a combustion chamber formed almost at the center of the piston head portion, a nozzle insertion hole formed almost at the center of the combustion chamber, and communication holes spaced from each other and arranged around the nozzle insertion hole;

heat insulating air layers formed between a wall surface of the cavity in the piston body and the combustion chamber structure; and

a mounting ring made of almost the same kind of material as that of the piston body and joined with the piston body, the mounting ring engaging the outer circumference of the combustion chamber structure installed in the cavity to fix the combustion chamber structure inside the cavity;

wherein a gap is formed between an inner circumferential surface of the mounting ring and an outer circumferential surface of the combustion chamber structure.

2. A piston structure with a combustion chamber, according to claim 1, wherein thermal expansion control members are installed between a top surface of a projecting portion provided at a lower outer periphery of the combustion chamber structure and a lower end surface of the mounting ring.

3. A piston structure with a combustion chamber, according to claim 1, wherein an upper outer circumferential surface of the mounting ring and the cavity wall surface of the piston body are fused together, and a gap is formed between a lower outer circumferential surface of the mounting ring and the cavity wall surface of the piston body.

4. A piston structure with a combustion chamber, according to claim 1, wherein gaskets for sealing are interposed between undercut portions formed on the inner circumferential surface of the mounting ring and stepped portions formed on the outer circumferential surface of the combustion chamber structure.

5. A piston structure comprising:

a piston body made of a metal material and having a cavity formed at the center of a piston head portion;

a combustion chamber structure made of a heat-resistant, high-temperature high-strength material installed in the cavity, the combustion chamber structure including a combustion chamber formed almost at the center of the piston head portion, a nozzle insertion hole formed almost at the center of the combustion chamber, and communication holes spaced from each other and arranged around the nozzle insertion hole;

heat insulating air layers formed between a wall surface of the cavity in the piston body and the combustion chamber structure; and

a mounting ring made of almost the same kind of material as that of the piston body and joined with the piston body, the mounting ring engaging the outer circumference of the combustion chamber structure installed in the cavity to fix the combustion chamber structure inside the cavity;

wherein an upper outer circumferential surface of the mounting ring and the cavity wall surface of the piston body are fused together, and a gap is formed between a lower outer circumferential surface of the mounting ring and the cavity wall surface of the piston body.

6. The piston structure according to claim 5, wherein thermal expansion control members are installed between a top surface of a projecting portion provided at a lower outer periphery of the combustion chamber structure and a lower end surface of the mounting ring.

7. A piston structure comprising:

a piston body made of a metal material and having a cavity formed at the center of a piston head portion;

a combustion chamber structure made of a heat-resistant, high-temperature high-strength material installed in the cavity, the combustion chamber structure including a combustion chamber formed almost at the center of the piston head portion, a nozzle insertion hole formed almost at the center of the combustion chamber, and communication holes spaced from each other and arranged around the nozzle insertion hole;

heat insulating air layers formed between a wall surface of the cavity in the piston body and the combustion chamber structure; and

a mounting ring made of almost the same kind of material as that of the piston body and joined with the piston body, the mounting ring engaging the outer circumference of the combustion chamber structure installed in the cavity to fix the combustion chamber structure inside the cavity;

wherein gaskets for sealing are interposed between undercut portions formed on the inner circumferential surface of the mounting ring and stepped portions formed on the outer circumferential surface of the combustion chamber structure.

8. The piston structure according to claim 7, wherein thermal expansion control members are installed between a top surface of a projecting portion provided at a lower outer periphery of the combustion chamber structure and a lower end surface of the mounting ring.