Plasma jet ignition engine and method

• US 4,203,393 A
• Filed: 01/04/1979
• Issued: 05/20/1980
• Est. Priority Date: 01/04/1979
• Status: Expired due to Term

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Motor Company
• Inventors: Giardini, Dante S.
• Primary Examiner(s): Argenbright, Tony M.
• Application Number:
  US06/000,957
• Time in Patent Office: 502 Days
• Field of Search: 123/30 C, 123/30 D, 123/32 B, 123/32 SP, 123/32 C, 123/32 ST, 123/143 B, 123/191 S, 123/191 SP
• US Class Current: 123/260
• CPC Class Codes: F02B 17/005 having direct injection in the combustion chamber
• CPC Class Codes: F02B 19/108 with fuel injection at least into pre-combustion chamber, i.e. injector mounted directly in the pre-combustion chamber
• CPC Class Codes: F02B 2023/085 using several spark plugs per cylinder
• CPC Class Codes: F02B 2023/108 Swirl flow, i.e. the axis of rotation of the main charge flow motion is vertical
• CPC Class Codes: F02B 2275/40 Squish effect
• CPC Class Codes: F02B 23/101 the injector being placed on or close to the cylinder centre axis, e.g. with mixture formation using spray guided concepts
• CPC Class Codes: F02B 51/06 involving rays or sound waves
• CPC Class Codes: F02F 1/242 Arrangement of spark plugs or injectors
• CPC Class Codes: F02F 3/26 having combustion chamber in piston head the surface thereof being covered F02F3/14
• CPC Class Codes: H01T 13/50 having means for ionisation of gap H01T13/52 takes precedence
• CPC Class Codes: H05H 1/52 using exploding wires or spark gaps H05H1/26 takes precedence; spark gaps in general H01T
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A method and apparatus for carrying out combustion in an internal combustion engine of the stratified charge type is disclosed. The piston and cylinder are shaped in a manner to define a variable volume space and a main combustion chamber residing as a cavity in the top face of the piston, the cavity being in communication with the variable volume space. The cylinder has an intake port oriented to induce a swirl motion to air inducted into the variable volume space.

A shock wave chamber is defined with walls projecting from the cylinder head into the main combustion chamber when the piston in its top dead center position. The shock wave chamber (or intermediate chamber) has openings to permit circulatory transfer motion of the air to enter and exit from the central bottom thereof. The intermediate chamber is adapted to receive a plasma sonic jet directed axially downwardly therethrough to penetrate the exit opening of said intermediate chamber. Fuel injection is timed to introduce a spray of fuel to said intermediate chamber to be ignited by said plasma sonic torch passing therethrough to promote a flaming jet which extends into said main combustion chamber for completion of combustion.

Claims

1. An apparatus for carrying out combustion in an internal combustion engine, said engine having a piston and cylinder effective to define a variable volume space and a main combustion chamber residing as a cavity in the top of the piston and communicating with the variable volume space, said cylinder having an intake port oriented to induce a swirl motion to air inducted into said variable volume space, and said space being varied in volume by said piston during compression to induce a high radially inwardly squish motion to said air to form a circulatory path having an air column entering and extending into the central region of said main combustion chamber and exiting therefrom along the sides, said swirl motion and squish motion cooperating to impart a circulatory transfer motion to charge elements in said main chamber, the improvement comprising:

(a) means defining a shock wave chamber integral with said cylinder and having walls extending into said piston cavity when said piston is in a substantially top dead center condition, said shock wave chamber having an exit and an entrance respectively aligned with the path of the circulatory transfer motion of said charge elements,

(b) means defining a plasma cavity in communication with said shock wave chamber, said plasma cavity having an orifice communicating with said shock wave chamber at a side opposite from said exit, said orifice being aligned with the exit of said shock wave chamber,

(c) means for injecting fuel into said shock wave chamber during compression so that the charge elements are forced to enter said plasma cavity momentarily prior to ignition,

(d) means for applying a high energy discharge about 200 millijoules, through said plasma cavity causing the charge elements forced thereinto to be shock heated to an ionized condition and increased in pressure so that the ionized gas is ejected as a directed body of combusted ionized gases through said orifice, said ionized plasma jet igniting the mixture within said shock wave chamber and extending outwardly from the exit thereof preceded by said shock wave to additionally ignite the gaseous mixture in the main combustion chamber, said plasma jet extending through said shock wave cavity into the air column extending through said main combustion chamber.

2. The apparatus as in claim 1, in which the entrance to said shock wave chamber is comprised of a plurality of openings in the side walls of said chamber and arranged to be aligned with the squish motion of said air during the latest stages of compression.

3. The apparatus as in claim 1, in which the orifice of said plasma cavity is in the dimensional range of 0.052-0.11 inches.

4. The apparatus as in claim 1, in which said plasma cavity has a volume limited to about 0.75×

10^-3 in³.

5. The apparatus as in claim 1, in which the exit from said shock wave cavity is comprised of a circular opening having a diameter slightly in excess of the diameter of the ionized plasma jet plume.

6. The apparatus as in claim 1, in which the air-fuel ratio in said shock wave chamber during combustion is in the range of 18-26.

7. The apparatus as in claim 1, in which said means for supplying an energy discharge is effective to carry out said discharge for a period of 5-26°

crank rotation, and in which said means for supplying fuel injection is effective to carry out said injection for a period of 60°

of crank rotation.

8. The apparatus as in claim 1, in which said main combustion chamber has means to prevent absorption and promote reflectance of said shock wave in a direction complimentary to said circulatory transfer motion of said charge elements.

14. The method as in claim 8, in which ignition is initiated at about 16°

before top dead center.

9. A method of carrying out combustion in an internal combustion engine, said engine having a piston and cylinder effective to define a variable volume space and a main combustion chamber residing as a cavity in the top face of the piston in communication with the variable volume space, the steps comrising:

(a) interposing walls to define an intermediate chamber and to segregate a portion of the variable volume space, said chamber projecting into said main combustion chamber when the piston is substantially at top dead center, said intermediate chamber having an entrance and an exit aligned with the predetermined circulatory path of gases in said space,

(b) inducting air into said variable volume space with a swirling motion about the axis of said cylinder,

(c) compressing the air within said variable volume space and imparting a high radially inwardly squish motion to the air therein as said piston progressively approaches top dead center, said swirling motion and squish motion combining to define a circulatory path having a transfer motion from said variable volume space into said main combustion chamber defining a central air column which exits from said main combustion chamber along the sides thereof,

(d) generating a sonic plasma jet having an energy level of at least 200 millijoules, and directing said jet through said intermediate chamber so as to penetrate the exit thereof and extend into said main combustion chamber, said plasma jet having a turbulating action and igniting action to promote combustion throughout said intermediate chamber and main combustion chamber, said jet also serving to aspirate air from said variable volume space through said entrance openings into said intermediate chamber and outwardly through said exit opening along with said jet, and

(e) introducing a spray of fuel into said intermediate chamber in a predetermined time duration relative to the entrance of said plasma jet thereinto.

10. The method as in claim 9, in which the walls of said intermediate chamber are sized so as to retain residual heat from previous combustion cycles for promoting quicker vaporization of fuel introduced thereinto during step (e).

11. The method as in claim 9, in which the entrance area of each said intermediate chamber openings is less than the area of the exit opening.

12. The method as in claim 9, in which the main combustion chamber is provided with a centrally located splitter projection at the base thereof, effective to promote the spreading of the air column as it proceeds downwardly through said main combustion chamber and to reflect the shock wave to the side walls of the combustion chamber, and said main combustion chamber having undercut walls effective to promote the recircultion of air and re-reflectance of said shock wave in said main combustion chamber.

13. The method as in claim 9, in which fuel is injected into said intermediate chamber to provide a localized air-fuel ratio therein of 18-26.