Device for protecting against accidental contact and method for protecting against accidental contact of a displaceable part

• US 7,173,537 B2
• Filed: 07/25/2003
• Issued: 02/06/2007
• Est. Priority Date: 12/23/2002
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Voigtlaender, Klaus
• Primary Examiner(s): Wu; Daniel
• Assistant Examiner(s): PHAM, LAM P
• Application Number:
  US10/509,342
• Publication Number:
  US 20050145080A1
• Time in Patent Office: 1,292 Days
• Field of Search: 340552-554, 340/686.6, 340/573.1, 340562-567, 83/58, 83/75, 83/767, 83/621, 834/362, 834/772, 837/81, 318/16, 318/478
• US Class Current: 340/585
• CPC Class Codes: B23D 59/005 for preventing collision of saw blades with other machine parts or workpieces
• 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 19/00 Safety guards or devices specially adapted for wood saws; Auxiliary devices facilitating proper operation of wood saws
• CPC Class Codes: F16P 3/147 using electro-magnetic technology, e.g. tags or radar
• CPC Class Codes: Y10T 83/081 With randomly actuated stopping means
• CPC Class Codes: Y10T 83/088 Responsive to tool detector or work-feed-means detector
• CPC Class Codes: Y10T 83/152 And modify another operation
• CPC Class Codes: Y10T 83/175 With condition sensor
• CPC Class Codes: Y10T 83/6638 Unattached manual work pusher
• CPC Class Codes: Y10T 83/704 With work-support and means to vary relationship between tool and work support
• CPC Class Codes: Y10T 83/773 Work-support includes passageway for tool [e.g., slotted table]

Abstract

The device according to the invention has a sensor (5) for generating and detecting an electromagnetic field situated in the vicinity of a moving part (1) that should not be touched. The device according to the invention also has an evaluation unit (8) that is connected to the sensor (5) in order to evaluate sensor signals that can be generated by the sensor (5), wherein the evaluation unit (8) can generate an evaluation signal. Finally, a control unit (9) connected to the evaluation unit (8) is provided, which is designed and can be operated so as to control the movement of the part (1) as a function of the evaluation signal.

Claims

1. A device for protecting a body part of a person from contact with a rotating saw blade of a circular saw, comprising a sensor for generating and detecting an electromagnetic field situated in the vicinity of the saw blade (1);

an evaluation unit (8) connected to the sensor (5) for evaluation of sensor signals that are generated by the sensor (5), and generation of an evaluation signal; and

a control unit (9) connected to the evaluation unit (8), which is configured so as to control a movement of the saw blade (1) as a function of the evaluation signal, wherein the sensor (5) is positioned on an underside (4.1) of a jam guard (4) for the saw blade (1).

2. The device according to claim 1, characterized in that another sensor (5.2) is provided, wherein the two sensors (5.1, 5.2) are positioned on the two sides of the saw blade (1).

3. The device according to claim 1, characterized in that three additional sensors (5.2, 5.3, 5.4) are provided, wherein two sensors (5.1, 5.3;

5.2;

5.4) are positioned on each side of the saw blade (1).

4. The device according to claim 1, characterized in that the sensor (5) has a flat antenna (12) for generating electromagnetic waves.

5. The device according to claim 4, characterized in that an oscillatory circuit connected to the antenna (12) is provided and that the evaluation unit (8) is designed so that it can evaluate the detuning of the oscillatory circuit.

6. The device according to claim 4, characterized in that the waves that can be emitted by the antenna (12) lie in the range of the ISM band.

7. A method for protecting a body part of a person from contact with a rotating saw blade of a circular saw, comprising the steps of generating a high-frequency electromagnetic signal by an oscillatory circuit and an antenna (12) of a sensor (5) positioned on an underside (4.1) of a jam guard (4) for the saw blade (1);

detecting and monitoring a characteristic of the electromagnetic signal by an evaluation unit; and

based on the characteristic, making a determination as to whether influence should be exerted on the rotation of the saw blade (1).

8. The method according to claim 7, characterized in that the detuning of the oscillatory circuit serves as the characteristic.

9. The method according to claim 7, characterized in that the resonance frequency (fr) of the oscillatory circuit and/or the speed of the change in the resonance frequency and/or the resonance broadening serves as the characteristic.

10. A method for protection against contact with a moving part, characterized by means of the following steps:

a high-frequency electromagnetic signal is generated by an oscillatory circuit and an antenna (12),

an evaluation unit (8) detects and monitors a characteristic of the electromagnetic signal, and

based on the characteristic, a determination is made as to whether influence should be exerted on the movement of the moving part (1), and characterized in that a change in the torque of the moving part (1) is detected and the change is also used to determine whether influence should be exerted on the movement of the moving part (1).