Microcontroller for and a method of controlling operation of the safety clutch of a hand-held electric power tool

• US 6,700,341 B2
• Filed: 08/21/2001
• Issued: 03/02/2004
• Est. Priority Date: 08/24/2000
• Status: Active Grant

• Current Assignee: Hilti Aktiengesellschaft (Hilti Martin Family Trust)
• Original Assignee: Hilti Aktiengesellschaft (Hilti Martin Family Trust)
• Inventors: Böni, Hans, Schaer, Roland
• Primary Examiner(s): Masih, Karen
• Application Number:
  US09/933,970
• Publication Number:
  US 20020053892A1
• Time in Patent Office: 924 Days
• Field of Search: 318/432, 318/433, 318/434, 388/937, 180/142, 701/58
• US Class Current: 318/432
• CPC Class Codes: B25F 5/00 Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
• CPC Class Codes: Y10S 388/937 Hand tool

Abstract

A microcontroller for controlling operation of a safety clutch of a hand-held electrical power tool and which is arranged in a force transmitting chain of the tool, with the microcontroller including a unit (2,5,4;8) for processing at least one parameter of the power tool and for outputting a resulting parameter in form of a calculated torque (M¹), and a control unit (7) for comparing an actually measured torque (M) with the calculated torque (M¹), and for outputting a control signal (θ) when a difference between the actually measured and calculated torques exceeds a predetermined threshold.

Claims

1. An electrical hand-held power tool, comprising an electromotor (11) for driving the power tool (9);

a brake (12) for braking the electromotor;

a safety clutch (10) arranged in a force transmitting chain of the power tool; and

a micro-controller for controlling operation of the safety clutch (10), the microcontroller comprising means (2,5,4;

8) for processing at least one parameter of the power tool and for outputting a resulting parameter in form of a calculated torque M¹; and

a control unit (7) for comparing an actually measured torque M which is inputted in the control unit (7) as a first input parameter, with the calculated torque M¹ which is inputted into the control unit (7) as a second input parameter, and for outputting a control signal θ

when a difference between the actually measured and calculated torques exceeds a predetermined threshold.

2. A power tool according to claim 1, wherein the processing means comprises a first calculation unit (2) for transforming an input current I of a power tool electromotor, which is imputted in the first calculation unit (2) as an input parameter, over a motor diagram (3), into the calculated torque M¹ and a control unit (7) for comparing an actually measured torque, which is inputted into the control unit (7) as a first input parameter, with the calculated torque M;

at an output thereof.

3. A power tool according to claim 2, wherein the processing means comprises a second calculation unit (5) for transforming a measured rotational speed n of the power tool electromotor, which is imputted in the second calculation unit as an input parameter, over a friction diagram, into a friction torque at a second calculation unit output.

4. A microcontroller according to claim 3, wherein the processing means further comprises a summation point (4) having input means connected with the outputs of the first and second calculation units (2,5) and output means for outputting a calculated torque M¹ obtained by summation of input torques inputted from the first and second calculation units (2,5).

5. A power tool according to claim 1, wherein the processing means comprises a filter unit (8) for converting the actually measured torque M which is imputted therein, into the calculated torque M¹.