Fuel-metering arrangement having an electromagnetic fuel valve

Patent metadata

Field	Value
Publication number	US-10024272-B2
Application number	US-59167009-A
Country	US
Kind code	B2
Filing date	Nov 27, 2009
Priority date	Nov 27, 2008
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

The invention relates to a fuel-metering arrangement for the mixture-forming unit (2) of an internal combustion engine (10) in a portable handheld work apparatus. The mixture-forming unit comprises a fuel store (30), a switchable valve (40) and a fuel channel (20) which opens into an intake region of the engine (10). The valve (40) has an inflow port (41) which is connected to the fuel store (30) and an outflow port (42) which is connected to the fuel channel (20). A fuel column is mechanically moved by the switching of the valve. In order to compensate for this fuel column, the outflow port (42) is connected via a bypass channel (45) to the inflow port (41) and a flow valve (46) is mounted in the bypass channel (45). The flow valve (46) opens in flow direction (49) from the outflow port (42) to the inflow port (41) and blocks in the direction opposite thereto.

First claim

What is claimed is:

1. A fuel-metering arrangement for a mixture-forming unit of an internal combustion engine having an intake region, the fuel-metering arrangement comprising:
a fuel store configured to contain liquid fuel;
a switchable fuel valve having a liquid fuel inflow port connected to said fuel store;
a fuel channel opening into said intake region of said internal combustion engine and supplying liquid fuel in a first flow direction;
said switchable fuel valve having a liquid fuel outflow port connected to said fuel channel;
said liquid fuel inflow port being configured to have liquid fuel flow in thereto;
said liquid fuel outflow port being configured to have liquid fuel flow out therefrom;
a bypass channel connecting said liquid fuel outflow port to said liquid fuel inflow port and defining a second flow direction of the liquid fuel from said liquid fuel outflow port to said liquid fuel inflow port;
a flow valve mounted in said bypass channel and configured as a check valve for opening in said second flow direction from said outflow port to said inflow port and closing in said first flow direction;
said switchable fuel valve having a movable valve member configured to be surrounded by liquid fuel, perform a valve stroke (u), and be moved in or opposite to said first flow direction so as to open or close said switchable fuel valve;
said valve member being configured to move therewith a fuel column of liquid fuel, which bears on said valve member, with each movement in or opposite to said first flow direction of liquid fuel;
said check valve being configured to open and close in correspondence to a volume flow in said bypass channel so as to permit said fuel column, which is mechanically moved by said valve member, to flow off into said fuel store via said check valve in said bypass channel when said check valve opens;
a throttle configured in said bypass channel;
said throttle being disposed between said outflow port and said check valve;
said throttle being a first throttle having a first throttle resistance;
a second throttle configured in said fuel channel; and,
said second throttle having a second throttle resistance approximately equal to or slightly greater than said first throttle resistance.

2. The fuel-metering arrangement of claim 1 , wherein said first and second throttle resistances are determined by the configuration of the respective passthrough cross sections of said bypass channel and said fuel channel.

3. The fuel-metering arrangement of claim 2 , wherein said internal combustion engine is a small-volume engine.

4. The fuel-metering arrangement of claim 3 , wherein said small-volume engine is a two-stroke engine having a stroke volume of approximately 10 to 200 cm 3 .

5. The fuel-metering arrangement of claim 4 , wherein said two-stroke engine has a stroke volume of approximately 22 to 122 cm 3 .

6. The fuel-metering arrangement of claim 1 , wherein the fuel quantity metered by said switchable fuel valve is approximately 60 to 300 g/h.

7. The fuel-metering arrangement of claim 1 , wherein said intake region of said internal combustion engine includes an intake channel defining a venturi; and, said fuel channel opens into said intake channel in the region of said venturi.

8. The fuel-metering arrangement of claim 7 , wherein said fuel channel branches into a main nozzle path and an idle nozzle path.

9. The fuel-metering arrangement of claim 8 , wherein said intake region defines a flow direction of the combustion air drawn into said engine and said mixture-forming unit includes a main nozzle in said venturi and a throttle flap; and, said main nozzle path opens into said venturi via said main nozzle and said idle nozzle path opens in said flow direction of the combustion air in the region of said throttle flap.

10. The fuel-metering arrangement of claim 1 , wherein:
said valve member of said electromagnetically switchable fuel valve is a movable valve plate placed in said fuel channel between said fuel store and said mixture-forming unit;
fuel passes through said switchable valve in a flow direction; and,
said valve plate carries out an opening movement from a closed state into an open state in said flow direction of said fuel through said switchable valve.

11. The fuel-metering arrangement of claim 10 , wherein said switchable fuel valve, said bypass channel and said flow valve are arranged in a common component.

12. The fuel-metering arrangement of claim 1 , wherein said fuel in said fuel store is a liquid fuel.

13. The fuel-metering arrangement of claim 10 , wherein said fuel valve defines a longitudinal axis; and, said valve plate is movable along said longitudinal axis.

Assignees

• Schmidt Karsten
• Haegele Andreas
• Stihl Ag & Co Kg Andreas

Inventors

• Schmidt Karsten
• Hägele Andreas

Classifications

• F02M1/04

  the means to facilitate starting or idling being auxiliary carburetting apparatus able to be put into, and out of, operation, e.g. having automatically-operated disc valves · CPC title

• F02M17/04

  having fuel inlet valve controlled by diaphragm · CPC title

• F02M7/12 Primary

  Other installations, with moving parts, for influencing fuel/air ratio, e.g. having valves (F02M7/24 takes precedence) · CPC title