Two-cycle internal combustion engine with reduced unburned hydrocarbons in the exhaust gas

• US 5,311,854 A
• Filed: 01/25/1993
• Issued: 05/17/1994
• Est. Priority Date: 01/25/1993
• Status: Expired due to Term

• Current Assignee: BRQT Corporation
• Original Assignee: BRQT Corporation
• Inventors: Cullum, Harry
• Primary Examiner(s): ARGENBRIGHT, TONY MICHAEL
• Application Number:
  US08/007,937
• Time in Patent Office: 477 Days
• Field of Search: 123/65 R, 123/65 B, 123/65 BA, 123/73 A, 123/73 B, 123/73 C, 123/735, 123/162, 123/478, 123/561, 123/672, 123/676, 123/703
• US Class Current: 123/703
• CPC Class Codes: F02B 2075/025 two
• CPC Class Codes: F02B 25/10 with one piston having a smaller diameter or shorter stroke than the other
• CPC Class Codes: F02B 25/12 Engines with U-shaped cylinders, having ports in each arm
• CPC Class Codes: F02B 25/14 using reverse-flow scavenging, e.g. with both outlet and inlet ports arranged near bottom of piston stroke
• CPC Class Codes: F02B 33/38 of Roots type
• CPC Class Codes: F02B 39/08 Non-mechanical drives, e.g. fluid drives having variable gear ratio
• CPC Class Codes: F02B 39/16 Other safety measures for, or other control of, pumps
• CPC Class Codes: F02D 2400/04 Two-stroke combustion engines with electronic control
• CPC Class Codes: F02D 35/0015 using exhaust gas sensors F02D41/14 takes precedence
• CPC Class Codes: F02P 15/04 one of the spark electrodes being mounted on the engine working piston

Abstract

A two-cycle internal combustion engine configuration and control strategy in which the unburned hydrocarbon emissions in the exhaust gas are measured by a sensor in the exhaust manifold. The information from the sensor is used to control the outflow of air from a blower mixed with the fuel to vary the total volume of fuel and air to thus reduce unburned hydrocarbons in the exhaust gas.

Claims

1. In a two-cycle internal combustion engine operable with a source of fuel and a source of air, the engine including a cylinder with inlet and outlet ports, a piston slidable in the cylinder for opening and closing said ports, and fuel introduction means, the improvement comprising

a--sensor means for detecting unburned hydrocarbons in the exhaust gas and providing signal information,

b--blower with an outlet for directing its outflow into the cylinder inlet port, said fuel introduction means having an outlet upstream of and directed into said blower,

c--drive means driven by said engine and coupled to said blower for varying the the blower outflow, and

d--control means for receiving said signal information from said sensor means as to unburned hydrocarbons in the exhaust gas and for controlling the blower outflow into the cylinder to reduce unburned hydrocarbons in the exhaust gas.

2. An engine according to claim 1 wherein said fuel introduction means is a carburetor wherein fuel is drawn by air flow of the blower and the air/fuel ratio established by the carburetor setting is generally maintained when the air flow is reduced.

3. An engine according to claim 1 wherein said control means, upon receiving signal information from said sensor means as to the presence of unburned hydrocarbons in the exhaust gas, causes said blower to reduce the airflow and a proportionate amount of fuel into the cylinder.

4. An engine according to claim 1 wherein said sensor has a response time at least as fast as 100 msec. for detecting and evaluating unburned hydrocarbons.

5. An engine according to claim 1 further comprising a hydraulic pump driven by the engine and coupled to drive said blower.

6. An engine according to claim 1 wherein said control means comprises means for continuously receiving signal information data from said sensor means and continuously sending control signals to said drive means, thus providing dynamic feedback for continuously minimizing unburned hydrocarbons in the exhaust gas under changing operating conditions of said engine.

7. An engine according to claim 1 wherein said blower is a low pressure ratio Roots type air blower.

8. An engine according to claim 1 operable with a spark plug situated in the cylinder head and the piston has a crown top, the engine further comprising a ground electrode situated in said crown, said ground electrode being positioned relative to the spark plug so as to beneficially affect spark plasma and discharge current and enhance early flame development.

9. An engine according to claim 1 wherein said control means adjusts air flow from the blower and fuel flow therewith to optimize power output of the engine relative to the load condition.

10. In a two-cycle internal combustion engine operable with a source of fuel and a source of air received as an air fuel mixture having a predetermined air/fuel ratio, the engine including a cylinder with inlet and outlet ports, a piston slidable in the cylinder for opening and closing said ports, and fuel introduction means, the improvement comprising

a--sensor means for detecting unburned hydrocarbons in the exhaust gas and providing signal information,

b--a blower with an outlet directed into the cylinder inlet port,

c--drive means driven by said engine and coupled to said blower for varying the outlet air flow of the blower, and

d--control means for receiving said signal information from said sensor means as to unburned hydrocarbons in the exhaust gas and for controlling the blower air flow and fuel introduction into the cylinder to reduce unburned hydrocarbons in the exhaust gas, with the air/fuel ratio generally maintained when the air flow is reduced.

11. A method of reducing unburned hydrocarbons in the exhaust gas of a two-cycle engine which uses an air blower and fuel introduction by a carburetor operable with air flow of the air blower, comprising:

a--detecting unburned hydrocarbons in the exhaust gas and providing corresponding signal information,

b--determining the amount of reduction of air flow and included fuel into the engine cylinder to reduce unburned hydrocarbons in the exhaust gas, and

c--providing control means for varying said air flow and included fuel into the engine cylinder according to said determination in step b.

12. A method according to claim 11 wherein the air/fuel ratio is generally maintained while the air/flow is reduced.

13. A method according to claim 12 where the engine is subject to both high and low loading conditions, and wherein the control means reduces unburned hydrocarbons during high loading conditions without appreciably reducing engine power.

14. Method to improve fuel efficiency of a two-cycle engine which uses an air blower and fuel introduction by a carburetor operable with air flow of the air blower, comprising

a--detecting unburned hydrocarbons in the exhaust gas and providing corresponding signal information,

b--determining the amount of reduction of air flow and included fuel into the engine cylinder to reduce unburned hydrocarbons in the exhaust gas, and

c--providing control means for varying said air flow and included fuel into the engine cylinder according to said determination in step b.

15. A method according to claim 14 wherein said air flow and included flow forms a mixture having an air/fuel ratio and wherein said air/fuel ratio is generally maintained while said air flow is reduced.

16. A method according to claim 15 where the engine is subject to both high and low loading conditions, and wherein the control means reduces unburned hydrocarbons during high loading conditions without appreciably reducing engine power.

17. In a two-cycle internal combustion engine operable with a source of fuel and a source of air, the engine including a cylinder with inlet and outlet ports, a piston slidable in the cylinder for opening and closing said ports, and fuel introduction means, the improvement comprising

a--sensor means for sensing unburned hydrocarbons in the exhaust gas and providing signal information,

b--a blower with an outlet for directing an air flow into the cylinder inlet port, said fuel introduction means having an outlet upstream of and directed into said blower,

c--drive means driven by said engine and coupled to said blower for varying the outlet air flow of the blower, and

d--control means for receiving said signal information from said sensor means and determining unburned hydrocarbons in the exhaust gas and for controlling the blower air flow into the cylinder to reduce unburned hydrocarbons in the exhaust gas.

18. In a two-cycle internal combustion engine operable with a source of fuel and a source of air, the engine including a cylinder with inlet and outlet ports, a piston slidable in the cylinder for opening and closing said ports, and fuel introduction means, the improvement comprising

a--sensor means for sensing unburned hydrocarbons in the exhaust gas and providing signal information,

b--a blower with an outlet for directing its outflow into the cylinder inlet port,

c--drive means driven by said engine and coupled to said blower for varying the outflow of the blower, and

d--control means for receiving said signal information from said sensor means and for controlling the blower air flow and fuel introduction into the cylinder to reduce unburned hydrocarbons in the exhaust gas, with the air/fuel ratio generally maintained when the air flow is reduced.

19. A method of reducing unburned hydrocarbons in the exhaust gas of a two-cycle engine which uses an air introduction means and fuel introduction by a carburetor operable with air flow of the air introduction means for producing an air/fuel mixture to the engine cylinder, comprising:

a--evaluating the exhaust gas for presence of unburned hydrocarbons and providing corresponding signal information,

b--determining from said signal information the amount of reduction of air flow and included fuel into the engine cylinder to reduce unburned hydrocarbons in the exhaust gas, and

c--providing control means for varying said air flow and included fuel into the engine cylinder according to said determination in step b.

20. A method to improve fuel efficiency of a two-cycle engine which uses an air blower and fuel introduction by a carburetor operable with air flow of the air blower comprising

a--evaluating the exhaust gas for presence of unburned hydrocarbons and providing corresponding signal information,

b--determining from said signal information the amount of reduction of air flow and included fuel into the engine cylinder to reduce unburned hydrocarbons in the exhaust gas, and

c--providing control means for varying said air flow and included fuel into the engine cylinder according to said determination in step b.