Method for operating a handheld work apparatus having a combustion engine

Patent metadata

Field	Value
Publication number	US-9873193-B2
Application number	US-201414569866-A
Country	US
Kind code	B2
Filing date	Dec 15, 2014
Priority date	Dec 21, 2013
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

A handheld work apparatus has a combustion engine which drives a tool of the work apparatus via a centrifugal clutch. The centrifugal clutch couples in an engagement rotational speed range (n K ) which extends between a lower engagement rotational speed (n u ) and an upper engagement rotational speed (n o ). The engine has a fuel supply device, an ignition device, a control device and a device for detecting the rotational speed (n) of the engine. A method for operating the handheld work apparatus makes provision for the rotational speed profile of the combustion engine to be monitored in the engagement rotational speed range (n K ) and for the power (P) output for driving the tool to be increased from an operating power (P 1 ) to an increased power (P 2 , P 3 ) when the rotational speed profile corresponds with a predetermined rotational speed profile over a predetermined period of time (Δt).

First claim

What is claimed is:

1. A method for operating a handheld work apparatus which includes a centrifugal clutch, a work tool and a combustion engine for driving said work tool via said centrifugal clutch, said centrifugal clutch defining a coupling engaging rotational speed range (n K ) wherein said centrifugal clutch engages and said coupling engaging range extends between a lower coupling engaging rotational speed (n u ) and an upper coupling engaging rotational speed (n o ); said combustion engine including a fuel metering device, an ignition device, a control unit, a throttle lever, and a device for detecting the rotational speed (n) of said combustion engine, the method comprising the steps of:
monitoring the rotational speed profile of said combustion engine in said coupling engaging rotational speed range (n K ); and,
when the throttle lever is fully actuated, increasing the power (P) delivered to drive said work tool from an operating power (P 1 ) to an increased power (P 2 , P 3 ) when said rotational speed profile corresponds to a pregiven rotational speed profile over a pregiven time span (Δt) and when the rotational speed (n) is below the upper coupling engaging rotational speed (n o ).

2. The method of claim 1 , wherein said pregiven time span (Δt) is at least 0.1 s.

3. The method of claim 1 , wherein said increased power (P 2 , P 3 ) is at least 103% of said operating power (P 1 ).

4. The method of claim 1 , wherein said power (P) is increased in a discontinuous jump.

5. The method of claim 1 , wherein after the power increase, said power (P) is reduced at least once and again increased.

6. The method of claim 1 , wherein said power (P) is set back to said operating power (P 1 ) when said rotational speed (n) leaves said coupling engaging rotational speed range (n K ).

7. The method of claim 1 , wherein said power (P) is set back to said operating power (P 1 ) after the elapse of a pregiven time (Δt 2 ).

8. The method of claim 1 , wherein said power (P) is set back to said operating power (P 1 ) after reaching a pregiven temperature of said combustion engine.

9. The method of claim 1 , wherein said power (P) delivered by said combustion engine is increased by shifting the ignition time point (ZZP) of said combustion engine.

10. The method of claim 1 , wherein said power (P) delivered by said combustion engine is increased by changing the metered fuel quantity (x).

11. The method of claim 1 , wherein said power (P) delivered by said combustion engine is increased by changing the quantity of combustion air supplied to said combustion engine.

12. The method of claim 1 , wherein said power (P) delivered by said combustion engine is increased by changing the quantity (y) of air/fuel mixture supplied to said combustion engine.

13. The method of claim 1 , wherein, in addition to said work tool, said handheld work apparatus includes at least one additional consumer of energy which said combustion engine supplies with energy.

14. The method of claim 13 , wherein said power (P) is increased by switching off said at least one additional consumer of energy.

15. The method of claim 13 , wherein said power (P) is increased by reducing the energy supplied to said at least one additional consumer of energy.

16. The method of claim 1 , wherein said work apparatus further includes an operator-controlled element and said power (P) of said combustion engine is increased when said operator-controlled element is actuated.

17. A method for operating a handheld work apparatus which includes a centrifugal clutch, a work tool and a combustion engine for driving said work tool via said centrifugal clutch, said centrifugal clutch defining a coupling engaging rotational speed range (n K ) wherein said centrifugal clutch engages and said coupling engaging range extends between a lower coupling engaging rotational speed (n u ) and an upper coupling engaging rotational speed (n o ); said combustion engine including a fuel metering device, an ignition device, a control unit and a device for detecting the rotational speed (n) of said combustion engine, the method comprising the steps of:
monitoring the rotational speed profile of said combustion engine in said coupling engaging rotational speed range (n K ); and,
increasing the power (P) delivered to drive said work tool from an operating power (P 1 ) to an increased power (P 2 , P 3 ) when said rotational speed profile corresponds to a pregiven rotational speed profile over a pregiven time span (Δt), wherein said pregiven rotational speed profile is a constant rotational speed (n 1 ).

18. A method for operating a handheld work apparatus which includes a centrifugal clutch, a work tool and a combustion engine for driving said work tool via said centrifugal clutch, said centrifugal clutch defining a coupling engaging rotational speed range (n K ) wherein said centrifugal clutch engages and said coupling engaging range extends between a lower coupling engaging rotational speed (n u ) and an upper coupling engaging rotational speed (n o ); said combustion engine including a fuel metering device, an ignition device, a control unit and a device for detecting the rotational speed (n) of said combustion engine, the method comprising the steps of:
monitoring the rotational speed profile of said combustion engine in said coupling engaging rotational speed range (n K ); and,
increasing the power (P) delivered to drive said work tool from an operating power (P 1 ) to an increased power (P 2 , P 3 ) when said rotational speed profile corresponds to a pregiven rotational speed profile over a pregiven time span (Δt), wherein said handheld work apparatus has an additional drive motor and said power (P) is increased by switching in said additional drive motor.

Assignees

• Stihl Ag & Co Kg Andreas

Inventors

• Gorenflo Ernst
• Uhl Klaus-Martin
• Maier Georg

Classifications

• F02D41/1497

  With detection of the mechanical response of the engine · CPC title

• F02P5/1504

  with particular means during a transient phase, e.g. acceleration, deceleration, gear change (during starting F02P5/1506) · CPC title

• F02P5/045

  combined with electronic control of other engine functions, e.g. fuel injection (in general F02D37/02) · CPC title

• B27B17/08

  Drives or gearings; Devices for swivelling or tilting the chain saw · CPC title

• F02D2200/021

  Engine temperature · CPC title