Work Apparatus With Safety Equipment

• US 20100294097A1
• Filed: 05/20/2010
• Published: 11/25/2010
• Est. Priority Date: 05/21/2009
• Status: Active Grant

• Current Assignee: Yamabiko Corporation
• Original Assignee: Yamabiko Corporation
• Inventors: Aoki, Tatsuya, Ishimura, Tadashi
• Granted Patent: US 8,818,548 B2
• Time in Patent Office: Days
• US Class Current: 83/58
• CPC Class Codes: A01D 34/828 Safety devices
• CPC Class Codes: A01D 75/20 Devices for protecting men or animals
• CPC Class Codes: Y10T 83/04 Processes
• CPC Class Codes: Y10T 83/081 With randomly actuated stopping means
• CPC Class Codes: Y10T 83/175 With condition sensor
• CPC Class Codes: Y10T 83/85 Signal; e.g., alarm

Abstract

In a brush cutter (100), when it is determined based on acceleration information including frequency components, supplied from an acceleration sensor (24) included in the brush cutter (100) that the acceleration shows a peak in a range of frequencies lower than 100 Hz, the flow moves to step S5 to amplify the acceleration peak. In next step S6, the acceleration peak is compared with a threshold. When the result of comparison shows that the acceleration peak is higher than the threshold, the flow moves to step S7 to produce a safety signal. The safety signal is output from the controller (26) to a high voltage generation circuit (30) to stop generation of a high voltage in the high voltage generating circuit (30). In this manner, the acceleration sensor (24) is used to detect any unexpected, sudden danger, while diminishing influence of the acceleration caused by vibration inherent to the own nature of the work apparatus, its intended regular operation and its posture change in regular operation.

Claims

1. A work apparatus including a cutting tool and equipped with a safety device for stopping motion of the cutting tool upon detection of a particular phenomenon possibly inviting an unexpected, unsafe situation from acceleration information received from an acceleration sensor, comprising:

an acceleration sensor mounted on said work apparatus;

an arithmetic operation means supplied with acceleration information from the acceleration sensor and executing arithmetic operation of the acceleration information to find out a peak in acceleration included in the acceleration information;

a frequency range judgment means for judging whether or not the acceleration peak found out by said arithmetic operation means is within a first frequency range in which acceleration peaks indicative of phenomena possibly inviting any unexpected, unsafe situations normally appear;

a comparison means for comparing the acceleration peak with a threshold when the acceleration peak is determined by the frequency range judgment means to be within said first frequency range; and

an output means for issuing a safety signal to a disabling means when the result of comparison by said comparison means indicates that the acceleration peak is higher than the threshold, said disabling means responsively disabling said cutting tool of said work apparatus directly or indirectly to stop the cutting tool from moving.

2. The work apparatus according to claim 1, wherein the safety device further includes an amplification means for amplifying the acceleration peak in the first frequency range before the comparison by the comparison means.

3. A work apparatus including a cutting tool and equipped with a safety device for stopping motion of the cutting tool upon detection of a particular phenomenon possibly inviting an unexpected, unsafe situation from acceleration information received from an acceleration sensor, comprising:

an acceleration sensor mounted on the work apparatus;

a filtering means supplied with acceleration information from said acceleration sensor and extracting, from the frequency of the acceleration included in the acceleration information, information on acceleration in a first frequency range in which acceleration peaks indicative of phenomena possibly inviting any unexpected, unsafe situations normally appear while excluding acceleration information in a second frequency range in which acceleration peaks caused by vibration inherent to the own nature of said work apparatus or intended regular operation of the work apparatus appear;

an arithmetic operation means for executing arithmetic operation of the extracted acceleration information in said first frequency to find out an acceleration peak;

a comparison means for comparing the acceleration peak found out by said arithmetic operation means with a threshold; and

an output means for issuing a safety signal to a disabling means when the result of comparison by said comparison means indicates that the acceleration peak is higher than the threshold, said disabling means responsively disabling said cutting tool of said work apparatus directly or indirectly to stop the cutting tool from moving.

4. The work apparatus according to claim 3, wherein the safety device further includes an amplification means for amplifying the acceleration peak in the first frequency range before the comparison by the comparison means.

5. A work apparatus including a cutting tool and equipped with a safety device for stopping motion of the cutting tool upon detection of a particular phenomenon possibly inviting an unexpected, unsafe situation from acceleration information received from an acceleration sensor, comprising:

an internal combustion engine mounted in a drive unit in which a drive source for driving said cutting tool is provided;

an acceleration sensor attached to said drive unit in such an orientation that a detection axis of said acceleration sensor extends aslant from an axial line of a cylinder bore of said internal combustion engine;

an arithmetic operation means supplied with acceleration information from said acceleration sensor and executing arithmetic operation of the acceleration information to find out an acceleration peak;

a frequency range judgment means for judging whether or not the acceleration peak found out by said arithmetic operation means is within a first frequency range in which acceleration peaks indicative of phenomena possibly inviting any unexpected, unsafe situations normally appear;

an amplification means for amplifying the acceleration peak in the first frequency range when the frequency range judgment means determines that the frequency of the acceleration peak is in the first frequency range;

a first comparison means for comparing the acceleration peak amplified by the amplification means with a first threshold;

a second comparison means for comparing the acceleration peak with a second threshold when the frequency range judgment means determines that the frequency of the acceleration peak is in a frequency out of the first frequency range; and

an output means for issuing a safety signal to a disabling means when comparison of said first comparison means results in determining that the acceleration peak in the first frequency range is equal to or higher than the first threshold or when comparison of said second comparison means results in determining that the acceleration peak in the acceleration peak in the frequency range out of the first frequency range is equal to or higher than the second threshold, said disabling means responsively disabling said cutting tool of said work apparatus directly or indirectly to stop the cutting tool from moving.

6. The work apparatus according to claim 5, wherein a common threshold is used as the first and second thresholds.

7. A work apparatus including a cutting tool and equipped with a safety device for stopping motion of the cutting tool upon detection of a particular phenomenon possibly inviting an unexpected, unsafe situation from acceleration information received from an acceleration sensor, comprising:

an internal combustion engine mounted in a drive unit in which a drive source for driving said cutting tool is provided;

an acceleration sensor attached to said drive unit in such an orientation that a detection axis of said acceleration sensor extends aslant from an axial line of a cylinder bore of said internal combustion engine;

a frequency range judgment means supplied with acceleration information from said acceleration sensor and judging whether an acceleration indicated by the acceleration information has a frequency in a first frequency range in which acceleration peaks indicative of phenomena possibly inviting any unexpected, unsafe situations normally appear or in a frequency range other than the first frequency range;

a first arithmetic operation means for executing arithmetic operation of the acceleration having the frequency in the first frequency range to find out an acceleration peak;

an amplification means for amplifying the acceleration peak found out from the acceleration having the frequency in the first frequency range;

a second arithmetic operation means for executing arithmetic operation of the acceleration having a frequency in the frequency range other than the first frequency range to find out an acceleration peak;

a first comparison means for comparing the acceleration peak in the first frequency range amplified by the amplification means with a first threshold;

a second comparison means for comparing the acceleration peak in the frequency range other than the first frequency range, which has been found out by the second arithmetic operation means, with a second threshold;

an output means for issuing a safety signal to a disabling means when comparison of said first comparison means results in determining that the acceleration peak in the first frequency range is equal to or higher than the first threshold or when comparison of said second comparison means results in determining that the acceleration peak in the acceleration peak in the frequency range out of the first frequency range is equal to or higher than the second threshold, said disabling means responsively disabling said cutting tool of said work apparatus directly or indirectly to stop the cutting tool from moving.

8. The work apparatus according to claim 7, wherein a common threshold is used as the first and second thresholds.