Electronic compensation system

• US 6,186,117 B1
• Filed: 10/09/1997
• Issued: 02/13/2001
• Est. Priority Date: 10/09/1996
• Status: Expired due to Term

• Current Assignee: Bombardier Recreational Products Incorporated (Bombardier Incorporated)
• Original Assignee: Bombardier Incorporated
• Inventors: Matte, Sylvain
• Primary Examiner(s): MILLER, CARL STUART
• Application Number:
  US08/948,064
• Time in Patent Office: 1,223 Days
• Field of Search: 123/73.AD, 123/437, 123/438, 261/DIG.67
• US Class Current: 123/437
• CPC Class Codes: F02M 1/14 dependent on pressure in combustion-air- or fuel-air-mixture intake dependent on both pressure in combustion-air or fuel-air-mixture intake and engine temperature F02M1/10
• CPC Class Codes: F02M 7/127 Altering the float-chamber pressure enriching the fuel-air mixture during starting by depressing float to flood carburettor F02M1/18
• CPC Class Codes: Y10S 261/67 Carburetors with vented bowl

Abstract

The air/fuel mixture ratio supplied to an internal combustion engine of a vehicle is modified to achieve a constant mass flow rate in spite of changes in atmospheric temperature and pressure conditions by employing an electronic compensation system. The system has sensors which detect air temperature and barometric pressure, from which signals are developed controlling the float bowl pressure in the engine carburettors, thus modifying the air/fuel mixture ratio as desired. The system also includes provision for enriching the fuel content of the mixture supplied to the engine to provide an oversupply of fuel in cold start situations.

Claims

1. A method for adjusting the air/fuel mixture ratio for an engine during a cold start, comprising:

(a) supplying fuel from a float chamber to a venturi of a caburetor to be mixed with air and delivered to said engine;

(b) generating a flow of pressurized air from pressure fluctuations within a crankcase of said engine;

(c) supplying said flow to a control unit by a connecting line;

(d) sensing the temperature of the engine and generating a signal when said temperature is below a normal operating temperature range;

(e) supplying said signal to said control unit; and

(f) utilizing said flow to elevate the pressure within said float chamber to increase fuel flow into the venturi and thus increase the fuel content of said mixture during periods when said signal is received;

wherein said communication line delivers a flow of pressurized air at low speeds of rotation of the engine corresponding to cranking thereof, and

wherein a mechanical pump, driven by pressure pulses generated in the crankcase chamber of the engine delivers the flow of pressurized air at speeds corresponding to idling and higher engine speeds.

2. A method as claimed in claim 1, wherein said pump is a diaphragm pump having a moveable diaphragm in its driving chamber side that is exposed to said pressure pulses, and in its pumping chamber side, having an inlet and an outlet respectively controlled by one way valves.

9. A method as claimed in claim 2, wherein the driving chamber side of the pump is connected to a first chamber of the engine crankcase and the inlet of the pumping chamber side of the pump is connected to a separate second chamber of the engine crankcase.

3. A fuel supply control system for controlling the air/fuel ratio for an engine that has a crankcase chamber which is subject to pressure fluctuations during operation, comprising:

an engine temperature sensor for generating a first signal indicative of engine temperature;

a pressure generator for producing a flow of pressurized gas in response to said pressure fluctuations in said crankcase chamber;

a control unit connected to said engine temperature sensor for selectively utilizing said first signal to apply pressure from said pressure generator to enrich the fuel content of said mixture when said first signal indicates an engine temperature that is below a normal range of engine operating temperatures;

said system including an elongate manifold having first and second closed hollow chambers, said first hollow chamber being in communication with a float chamber of each carburetor of said engine, said second hollow chamber being in communication with a venturi of each said carburetor;

communicating between said first and second hollow chambers being controlled by a solenoid valve connected therebetween;

a second solenoid valve being coupled to connect said flow of pressurized gas to said first chamber;

said first and second solenoid valves being driven in respective duty cycles by said control unit.

4. A manifold for use in a fuel supply control system for an internal combustion engine having a plurality of carburetors each having a float bowl from which fuel is supplied to a respective venturi, said manifold comprising:

elongate first and second closed chambers extending substantially parallel to one another;

each said chamber including flow connections for connecting the first chamber to the float bowl of each carburetor and for connecting the second chamber to the venturi of each carburetor;

a first valve for controlling delivery of a pressurized air flow to the first chamber, and a second valve for controlling air flow between said first and second chambers.

5. A kit of parts for providing a fuel supply control system on an engine in a vehicle, said kit of parts comprising:

(a) at least one sensor for sensing a condition selected from engine temperature, air pressure, and air temperature;

(b) an electronic control unit;

(c) a manifold for connecting to a plurality of carburetors of the engine, each carburetor having a float bowl from which fuel is supplied to a respective venturi, the manifold including,

elongate first and second closed chambers extending substantially parallel to one another;

each chamber including flow connections for respectively connecting the first chamber to the float bowl of each carburetor and for connecting the second chamber to the venturi of each carburetor;

a first valve for controlling delivery of a pressurized air flow to the first chamber, and a second valve for controlling air flow between said first and second chambers;

(d) a pump for delivering a flow of pressurized air to said manifold;

(e) electrical connectors for coupling said electronic control unit to said at least one sensor and to said solenoid valve; and

(f) pipe connectors to connect said pump to said manifold and for connecting said first and second manifold chambers to the engine carburetor.

6. A method for adjusting the air/fuel mixture ratio for an engine during a cold start, comprising:

(a) supplying fuel from a float chamber to a venturi of a carburetor to be mixed with air and delivered to said engine;

(b) generating a flow of pressurized air from pressure fluctuations within a crankcase of said engine;

(c) supplying said flow to a control unit by a connecting line;

(d) sensing the temperature of the engine and generating a signal when said temperature is below a normal operating temperature range;

(e) supplying said signal to said control unit; and

(f) utilizing said flow to elevate the pressure within said float chamber to increase fuel flow into the venturi and thus increase the fuel content of said mixture during periods when said signal is received;

wherein, at cranking speed of said engine, said flow of pressurized air is generated through said connecting line, which is provided with a one-way flow valve to prevent reverse flow of pressurized air therein during intervals when pressure in the crankcase is reduced, and

wherein, at speeds of idle and higher, said flow of pressurized air is generated by a diaphragm pump powered by pressure fluctuations within said crankcase.

7. A method as claimed in claim 6, wherein said control unit includes a solenoid valve and said flow is delivered to said flow chamber through said solenoid valve.

8. A fuel supply control system for controlling the air/fuel ratio for an engine that has a crankcase chamber which is subject to pressure fluctuations during operation, comprising:

an engine temperature sensor for generating a first signal indicative of engine temperature;

a pressure generator for producing a flow of pressurized gas in response to said pressure fluctuations in said crankcase chamber;

a control unit connected to said engine temperature sensor for selectively utilizing said first signal to apply pressure from said pressure generator to enrich the fuel content of said mixture when said first signal indicates an engine temperature that is below a normal range of engine operating temperatures;

a pressure sensor being connected to the control unit to deliver thereto a signal that is indicative of atmospheric pressure, said control unit being operative to reduce the fuel content of said mixture in proportion to reductions in atmospheric pressure signaled by said pressure sensor by applying a reduced pressure to a float bowl of a carburetor of the engine; and

an air temperature sensor which is coupled to said control unit to provide a third signal thereto that is indicative of ambient air temperature, said control unit being operative to adjust the fuel content of said mixture to take account of variations in air density, said variations being proportional to ambient air temperature.

10. A fuel supply system for an engine, the control system being arranged to control the mass air/fuel mixture ratio delivered into the engine, the system comprising:

a first connecting line for connecting an interior of a float chamber of a carburetor of the engine to a venturi of the carburetor for exposing the float chamber to an air pressure at the venturi and adjusting a pressure on the fuel in the float chamber;

a control valve positioned in the first connecting line for controlling the flow rate and amount of pressure differential between the venturi and the fuel in the float chamber; and

a control unit for controlling the valve to substantially maintain the mass air/fuel mixture ratio constant as atmospheric air density changes by increasing the pressure on the fuel in the float chamber with respect to the pressure in the venturi as air density increases and decreasing the pressure on the fuel in the float chamber with respect to the pressure in the venturi as air density decreases.

11. A fuel supply control system for an engine as in claim 10, and further comprising:

at least one sensor for sensing at least one of barometric pressure and atmospheric temperature and supplying such sensed information to the control unit;

wherein the control unit controls the control valve in accordance with the sensed information to maintain the substantially constant mass air/fuel mixture ratio.

12. A fuel supply control system for an engine as in claim 10,

wherein the control unit controls a duty cycle of the control valve to control the flow rate of the valve.

13. A fuel supply control system for an engine as in claim 12, wherein the duty cycle is small at a standard operating altitude and is increased by the control unit to decrease the pressure differential between the venturi and the float chamber as the engine is operated at a higher altitude where the barometric air pressure is lower.

14. A fuel supply control system for an engine as in claim 13, wherein at a 100% duty cycle the vacuum in the float chamber will be approximately 40% of the vacuum at the venturi.

15. A fuel supply control system for an engine as in claim 14, wherein the first connecting line connects to the venturi adjacent an orifice for supplying fuel from the float chamber to the venturi.

16. A fuel supply control system for an engine as in claim 15, wherein the control unit is an ECU.

23. A method as in claim 15, wherein the controlling of the pressure differential is performed by an ECU.

17. A method for controlling the mass air/fuel mixture ratio delivered into an engine from a carberot to compensate for changes in atmospheric air density, the method comprising:

connecting an interior of a float chamber of the carburetor to a venturi of the carburetor for exposing the float chamber to an air pressure at the venturi and adjusting a pressure on the fuel in the float chamber;

controlling the amount of pressure differential between the venturi and on the fuel in the float chamber to substantially maintain the mass air/fuel mixture ratio constant as the atmospheric air density changes by increasing the pressure on the fuel in the float chamber with respect to the pressure in the venturi as air density increases and decreasing the pressure on the fuel in the float chamber with respect to the pressure in the venturi as air density decreases.

18. A method as in claim 17, and further comprising:

sensing at least one of barometric pressure and atmospheric temperature and controlling the pressure differential in accordance with the sensed information to maintain the substantially constant mass air/fuel mixture ratio.

19. A method as in claim 18,

wherein the pressure differential is controlled by controlling a duty cycle of a control valve interconnected between the venturi and the float chamber to control a flow rate of the control valve.

20. A method as in claim 19, wherein the duty cycle is controlled to be small at a standard operating altitude and is increased to decrease the pressure differential between the venturi and the float chamber as the engine is operated at a higher altitude where the barometric air pressure is lower.

21. A method as in claim 20, wherein at a 100% duty cycle the vacuum in the float chamber is controlled to be approximately 40% of the vacuum at the venturi.

22. A method as in claim 21, wherein the interior of the float chamber is connected to the venturi adjacent an orifice for supplying fuel from the float chamber to the venturi.