Handheld work apparatus having a device for starting an electric drive motor

Patent metadata

Field	Value
Publication number	US-10520134-B2
Application number	US-201715465435-A
Country	US
Kind code	B2
Filing date	Mar 21, 2017
Priority date	Mar 21, 2016
Publication date	Dec 31, 2019
Grant date	Dec 31, 2019

Abstract

A handheld work apparatus has a device for starting an electric drive motor via an actuating element which can be displaced in a handle counter to an actuating force and acts on a transmission element. The transmission element is shiftable from a rest position into an operating range, wherein the transmission element actuates a switching element and starts the motor. For shifting from the rest position into an end position, a shift force is applied. The shift force forms at least a portion of the actuating force. To keep the actuating force low after the motor is switched on, the displacement path of the transmission element is divided into a first segment and a second segment which includes the operating range. The shift force to be applied to the transmission element rises on the first segment of the path and, after a maximum, decreases on the second segment.

First claim

What is claimed is:

1. A handheld work apparatus comprising:
an electric motor;
a handle;
an actuating element arranged in said handle and configured to be displaceable to an operating position counter to an actuating force;
a transmission element coupled to said actuating element in a positionally dependent manner and configured to be adjustable from a rest position to an operating range in dependence upon a position of said actuating element;
an electrical switching element;
said transmission element being configured to actuate said electrical switching element in order to start said electric motor;
said transmission element being configured to be adjustable from said rest position along a displacement path to an end position via a shift force;
said shift force required for moving said transmission element forming at least a portion of said actuating force;
said displacement path including a first path segment adjoining said end position;
said displacement path including a second path segment adjoining said first path segment;
said second path segment including said operating range; and,
said shift force required for moving said transmission element increasing in said first path segment and decreasing in said second path segment after reaching a maximum.

2. The handheld work apparatus of claim 1 , wherein said actuating element is configured to be displaced counter to a spring force; and, said spring force and said shift force add up to said actuating force.

3. The handheld work apparatus of claim 2 , wherein a sum of said shift force and said spring force is constant over a partial section of said displacement path.

4. The handheld work apparatus of claim 1 , wherein said electrical switching element is configured to switch on said electric motor in a region around said maximum of said shift force.

5. The handheld work apparatus of claim 1 , wherein said transmission element is an intermediate lever rotatable about a lever axis.

6. The handheld work apparatus of claim 5 further comprising:
a coupling element configured to be displaceable via said actuating element;
said intermediate lever having a first lever arm; and,
said coupling element lying against said first lever arm.

7. The handheld work apparatus of claim 6 , wherein:
said coupling element and said lever axis of said intermediate lever define an effective lever length therebetween; and,
said effective lever length is configured to change in dependence upon a rotational angle of said intermediate lever.

8. The handheld work apparatus of claim 1 further comprising:
a switching cam configured to rotate about a cam axis; and,
said electrical switching element being configured to be switched by said switching cam.

9. The handheld work apparatus of claim 5 further comprising:
a tension rod;
a switching cam; and,
said intermediate lever having a lever arm connected to said switching cam via said tension rod.

10. The handheld work apparatus of claim 8 further comprising:
a tension rod;
said transmission element being an intermediate lever rotatable about a lever axis; and,
said intermediate lever having a lever arm connected to said switching cam via said tension rod.

11. The handheld work apparatus of claim 8 , wherein:
said electrical switching element defines a switching position; and,
said switching cam is configured to be rotatable beyond said switching position of said electrical switching element.

12. The handheld work apparatus of claim 8 , wherein:
said electrical switching element is configured as an operating switch having a switching leaf; and,
said switching cam includes a rising flank which, in a resting position of said switching cam, lies at a distance to said switching leaf of said electrical switching element.

13. The handheld work apparatus of claim 12 , wherein:
said switching cam further includes a run-out flank adjoining said rising flank;
and,
said run-out flank is formed as a circular arc segment around said cam axis.

14. The handheld work apparatus of claim 8 , wherein:
said electrical switching element includes a switching leaf defining an actuating axis;
said switching cam defines a contact point on said switching leaf;
said actuating axis of said switching leaf and said contact point of said switching cam on said switching leaf define a distance (S 1 , S 2 ) therebetween; and,
said distance (S 1 , S 2 ) forms a switching lever and is configured to increase when said switching cam is rotated.

15. The handheld work apparatus of claim 1 further comprising:
a switching cam configured to rotate about a cam axis;
a coupling element configured to be displaceable via said actuating element;
said transmission element having a tension rod;
said switching cam defining a coupling point for said tension rod;
said transmission element being an intermediate lever rotatable about a lever axis;
said coupling element and said lever axis of said intermediate lever defining a first effective lever length therebetween when said transmission element is in said rest position;
said coupling point and said lever axis of said intermediate lever defining a second effective lever length therebetween when said transmission element is in said rest position; and,
said first effective lever length being less than said second effective lever length.

Assignees

• Stihl Ag & Co Kg Andreas

Inventors

• Kolb Joachim
• Kraetzig David

Classifications

• B25F5/00

  Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for · CPC title

• A01G3/053 Primary

  motor-driven · CPC title

• F16P3/20 Primary

  for electric control systems · CPC title

• H02K7/10 Primary

  Structural association with clutches, brakes, gears, pulleys or mechanical starters · CPC title