Method and apparatus for determining an overtravel time of a machine

• US 8,665,328 B2
• Filed: 02/11/2010
• Issued: 03/04/2014
• Est. Priority Date: 02/13/2009
• Status: Active Grant

• Current Assignee: PILZ GmbH & Company KG
• Original Assignee: PILZ GmbH & Company KG
• Inventors: Doettling, Dietmar
• Primary Examiner(s): Tiv, Backhean
• Assistant Examiner(s): Chou, Alan S
• Application Number:
  US12/704,071
• Publication Number:
  US 20100208067A1
• Time in Patent Office: 1,482 Days
• Field of Search: 348/143, 744/69, 700/90
• US Class Current: 348/143
• CPC Class Codes: F16P 3/008 Devices for directly stopping or interrupting the drive or gear in case of danger to the machine, e.g. devices with clutches
• CPC Class Codes: F16P 3/142 using image capturing devices
• CPC Class Codes: Y10T 74/20 Control lever and linkage systems

Abstract

An apparatus for determining an overtravel time of a machine, which has a moveable machine part and an optoelectronic protection device, has a light source designed to produce a defined light spot. The protection device for the machine comprises a camera having an observation area in which at least one protection zone having a protection zone boundary is defined. The protection device produces a stop signal when an object enters the protection zone. The light spot simulates an object within the protection zone. The light source is supported by a support element designed to position the light source in the area of the protection zone boundary. An evaluation and control unit of the apparatus is designed to switch on the light source at a defined starting time, and to determine a time interval between the defined starting time and the reception of an “end” signal indicating that the machine part has come to rest.

Claims

1. An apparatus for determining an overtravel time of a machine having a moveable machine part and an optoelectronic protection device designed to stop movement of the machine part, wherein the protection device comprises a camera having an observation area in which at least one protection zone with a protection zone boundary is defined, and wherein the protection device produces a stop signal when an object enters the protection zone, the apparatus comprising:

a light source designed to produce a defined light spot for simulating an object within the protection zone,

a support element supporting the light source, with the support element being designed to position the light source in the area of the protection zone boundary, and

an evaluation and control unit having a first signal input for receiving an end signal indicating that the machine part has come to rest,

wherein the evaluation and control unit is designed to switch on the light source at a defined starting time, and to determine a time interval between the defined starting time and reception of said end signal.

2. The apparatus of claim 1, wherein the light source is a point light source.

3. The apparatus of claim 1, wherein the light source is an LED.

4. The apparatus of claim 1, wherein the light source is arranged such that it is largely free-standing on the support element.

5. The apparatus of claim 1, wherein the light source comprises a substantially transparent housing body.

6. The apparatus of claim 1, wherein the support element has a telescopic stand.

7. The apparatus of claim 1, wherein the support element has an adjustable head part on which the light source is arranged.

8. The apparatus of claim 1, wherein the evaluation and control unit has a second signal input for receiving an external trigger signal for switching on the light source.

9. The apparatus of claim 1, wherein the evaluation and control unit has a pushbutton for manually switching on the light source.

10. The apparatus of claim 1, wherein the protection device produces the stop signal upon detection of the light spot generated by the light source after switch on of the light source.

11. The apparatus of claim 10, wherein said protection device and said evaluation and control unit are connected to a controller adapted to control the moveable machine part, and further wherein said end signal is produced by said controller and supplied to said first signal input of said evaluation and control unit.

12. A method for determining an overtravel time of a machine having a moving machine part and an optoelectronic protection device designed to stop movement of the machine part, wherein the protection device comprises a camera having an observation area in which at least one protection zone with a protection zone boundary is defined, and wherein the protection device produces a stop signal when an object enters the protection zone, the method comprising the following steps:

providing at least one light source which can be selectively switched on and off,

moving the machine part,

generating a light spot within the protection zone by switching on the light source at a defined starting time, the light spot being designed to simulate an object within the protection zone,

detecting a stop time, at which the machine part comes to rest, and

determining a time interval between the starting time and the stop time.

13. The method of claim 12, wherein the light spot is generated precisely at the zone boundary.

14. The method of claim 12, wherein the machine and the light source are controlled by a controller, and further wherein the defined starting time is determined by the production of a turn-on signal by the controller to switch on the light source.

15. The method of claim 12, wherein the protection device produces the stop signal upon detection of the light spot generated by the light source after switching on of the light source.