Electrical power tool with a rotatable working tool

• US 20040103544A1
• Filed: 09/02/2003
• Published: 06/03/2004
• Est. Priority Date: 08/17/2000
• Status: Active Grant

• Current Assignee: Hilti Aktiengesellschaft (Hilti Martin Family Trust)
• Original Assignee: Hilti Aktiengesellschaft (Hilti Martin Family Trust)
• Inventors: Hartmann, Markus
• Granted Patent: US 7,856,724 B2
• Time in Patent Office: Days
• US Class Current: 30/388
• CPC Class Codes: B23Q 11/0092 actuating braking or stopping means
• CPC Class Codes: B27B 5/38 Devices for braking the circular saw blade or the saw spindle; Devices for damping vibrations of the circular saw blade, e.g. silencing B23D47/005 takes precedence
• CPC Class Codes: B27G 21/00 Safety guards or devices specially designed for other wood-working machines auxiliary devices facilitating proper operation of said wood-working machines
• CPC Class Codes: Y10T 83/099 Manually operated
• CPC Class Codes: Y10T 83/9379 At end of shaft
• CPC Class Codes: Y10T 83/9464 For rotary tool

Abstract

An electrical power tool includes a locking device (31) for securing the working tool (3) on a motor-driven shaft (2), a switch (7) for turning the shaft driving motor (M) on and off, a device (10) for braking the shaft (2), a safety element (8) connected with the braking device (10) and the switch (7) and having a safety position that corresponds to the braking position of the braking device (10) and a position of the switch (7) in which the switch (7) cannot turn the shaft driving motor (M) on, and a release position that corresponds to the release position of the braking device (10) and a position of the switch (7) in which the switch (7) turns the shaft-driving motor on, and a locking mechanism (21) operatively connected with the safety element (8) and the locking device (31) and displaceable between a locking position which corresponds to an unlocking position of locking device (31) and in which the safety element (8) is retained in its safety position thereof, and a release position in which the locking device (31) is in its locking position, and the safety element (8) occupies its release position.

Claims

1. An electrical power tool, comprising a motor-driven shaft (2) for supporting a circular working tool (3);

a motor (M) for driving the shaft (2);

locking means (31) for securing the circular working tool (3) on the shaft (2) and having a locking position in which the circular working tool (3) is fixedly secured on the shaft (2), and an unlocking position in which the circular working tool (3) can be removed from the shaft (2);

switch (7) operably connected with the shaft driving motor for turning the motor on and off;

a device (10) for braking the shaft (2); and

having a braking position in which it brakes totation of the shaft (2), and a release position in which the shaft (2) can freely rotate;

a safety element (8) connected with the braking (10) and the switch (7) and having a safety position that corresponds to the braking position of the braking device (10) and a position of the switch (7) in which the switch cannot turn the shaft driving motor (M) on; and

a release position that corresponds to the release position of the braking device (10) and a position of the switch (7) in which the switch (7) turns the shaft-driving motor (M) on; and

a locking mechanism (21) connected with the braking device (10) and the locking means (31) and displaceable between a locking position thereof which corresponds to an unlocking position of the locking means (31) and a braking position of the braking device (10) in which the safety element (8) is retained in the safety position thereof, and a release position thereof in which the locking means (31) is in its locking position and the braking device (10) is in its release position in which the safety element (8) occupies the release position thereof.

2. An electrical power tool according to claim 1, further comprising a locking lever (5) for actuating both the locking means (31) and the locking mechanism (21) and displaceable between a locking position that corresponds to the locking position of the locking means (31) and the release position of the locking mechanism (21), and a release position that corresponds to the unlocking position of the locking means (31) and the locking position of the locking mechanism (21), whereby the shaft (2) is braked, and the switch (7) is prevented from turning the shaft driving motor on in the unlocking position of the locking means, and the shaft (2) can freely rotate and the switch (7) can actuate the shaft drive motor in the locking position of the locking means.

3. An electrical power tool according to claim 2, wherein the braking device (10) has a groove (20), and the locking mechanism (21) has a locking member (25) engaging in the groove (20) of the braking device (10) in the release position of the locking lever (5) for retaining the braking device (10) in the braking position thereof.

4. An electrical power tool according to claim 3, further comprising a bolt (26) for pivotally supporting the locking member (25) for pivotal movement between engaging and disengaging positions.

5. An electrical power tool according to claim 3, wherein the locking lever (5) has cam means (24) engaging the locking member (25) for guiding the locking member (25) between an engaging position of the locking member (25) and a disengaging position thereof corresponding to the release position of the braking device (10).

6. An electrical power tool according to claim 5, wherein the cam means (24) has a section engagable with the locking member (25) for retaining the locking member (25) in the engaging position thereof.

7. An electrical power tool according to claim 1, wherein the locking mechanism is formed of a plastic material.

8. An electrical power tool according to claim 1, further comprising means (11) for mechanically connecting the safety element (8) with the braking device (10).

9. An electrical power tool according to claim 1, wherein the shaft (2) is formed of a first section (2a) connectable with the drive motor (M), and a second section (2b) connectable with the working tool (3), and wherein the power tool further comprises gear means (30) for connecting the first (2a) and second (2b) sections, the locking device (3) being provided at an end of the second section (2b) remote from the gear means (30).

10. An electrical power tool according to claim 2, wherein the locking device (31) comprises a tension rod (32) for connecting the locking means (31) with the locking lever (5).