Brush cutter safety device

Abstract

To ensure the safety of people and objects around a brush cutter during a work.SOLUTION: A safety device of a brush cutter comprises a Doppler sensor provided in the vicinity of the brush cutter in operation and a processing device for processing the output of the Doppler sensor. The Doppler sensor is provided on clothing worn by an operator who operates the brush cutter. The processing device outputs a signal to stop driving the brush cutter when it detects an object approaching the brush cutter on the basis of the output of the Doppler sensor.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a safety device for a lawn mower.

Background Art

[0002] Conventionally, a lawn mower with a safety device is known. This prior art involves mounting an acceleration sensor on the lawn mower and activating the safety device when the detected value of the acceleration sensor is greater than a threshold value. The acceleration sensor is attached to the lawn mower in a posture where the detection axis is inclined with respect to the left-right direction of the lawn mower (see Patent Document 1 below).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the above-described prior art, by detecting forces in various directions applied to the lawn mower using an acceleration sensor, unexpected situations such as the lawn mower falling or the cutting blade colliding with an obstacle (kickback) can be detected, and the operation of the lawn mower can be stopped. This can ensure the safety of the operator performing work using the lawn mower.

[0005] On the other hand, since the lawn mower has a structural feature in which a cutting blade is equipped at the tip of a long operating rod, it is necessary to ensure safety not only for the operator performing work using the lawn mower but also for people and objects around the lawn mower during operation.

[0006] During brush cutting, workers have difficulty distinguishing surrounding sounds due to noise from the engine and the cutting blades. In addition, wearing protective equipment such as earplugs or earmuffs to block out this noise makes it difficult to hear surrounding sounds. Furthermore, concentrating on the position of the cutting blade while working can narrow the worker's field of vision. As a result, workers may not notice people or objects approaching and may turn around, pointing the long operating handle at the approaching person or object. To avoid such situations, there is a need for a safety device for brush cutters that can detect people or objects approaching the machine during operation.

[0007] This invention was proposed to address these circumstances. Specifically, the objective of this invention is to ensure the safety of people and objects around a brush cutter in operation by effectively detecting people and objects (approaching objects) approaching the brush cutter while it is in operation. [Means for solving the problem]

[0008] To solve these problems, the present invention has the following configuration. A safety device for a brush cutter comprising a Doppler sensor installed in close proximity to the brush cutter during operation and a processing device for processing the output of the Doppler sensor, wherein the Doppler sensor is installed on the clothing worn by the operator of the brush cutter and is positioned to avoid interference between the transmitted wave, which is directed behind the operator, and the main body of the brush cutter connected to the clothing. Furthermore, the orientation of the Doppler sensor is such that, when the brush-cutting work is being performed, the direction of transmission of the transmitted wave is directed approximately parallel to the ground. The safety device for a brush cutter is characterized in that the processing device outputs a signal to stop the operation of the brush cutter when it detects a person or object approaching the brush cutter based on the output of the Doppler sensor. [Effects of the Invention]

[0009] Having these features, the present invention can provide a safety device for a brush cutter that effectively detects people or objects approaching the brush cutter during operation using the output of a Doppler sensor. Furthermore, by installing the Doppler sensor on the worker's clothing, the influence of the brush cutter's movement during operation on the Doppler sensor can be reduced, and detection noise from the Doppler sensor can be easily eliminated. [Brief explanation of the drawing]

[0010] [Figure 1] An explanatory diagram showing a safety device for a brush cutter according to an embodiment of the present invention. [Figure 2] An explanatory diagram showing the operation of a brush cutter equipped with safety devices. [Figure 3] An explanatory diagram showing the function of the processing unit in the safety device of a brush cutter. [Figure 4] An explanatory diagram showing the safety device for a backpack-type brush cutter. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same reference numerals in different figures indicate parts with the same function, and redundant explanations in each figure will be omitted as appropriate.

[0012] In Figure 1, the brush cutter 10 comprises a main body 11, an operating rod 12 with its end connected to the main body 11, and a brush cutting unit 13 equipped at the tip of the operating rod 12. The drive configuration of the brush cutting unit 13 can be various, such as transmitting the rotation of a prime mover (engine or electric motor) mounted on the main body 11 to the brush cutting unit 13 via a transmission shaft in the operating rod 12, or mounting a prime mover (electric motor) on the brush cutting unit 13 and connecting the prime mover to a battery equipped on the main body 11 with wiring in the operating rod 12. Furthermore, the form of the brush cutting unit 13 itself can be any form, such as a rotating blade, a reciprocating blade, or a resin cord.

[0013] The safety device 1 provided by the brush cutter 10 includes a Doppler sensor 1A installed in close proximity to the brush cutter 10 during operation, and a processing unit 1B that processes the output of the Doppler sensor 1A. The Doppler sensor 1A is installed on the wearable garment Mw of the operator M who operates the brush cutter 10.

[0014] The processing unit 1B may have the Doppler sensor 1A integrated into it, or it may be installed separately on the worker M's clothing Mw, as shown in the figure. The worker M's clothing Mw here refers to clothing such as work clothes worn by the worker M, a belt or sash worn around the worker M's waist, a harness including a connecting member for connecting to the brush cutter 10, etc.

[0015] The Doppler sensor 1A transmits a wave to a predetermined detection range and receives a reflected wave returning from the detection range, outputting a signal that includes a Doppler signal. The Doppler signal has different frequencies depending on the change in distance to the moving object present in the detection range, based on the phase difference between the transmitted wave and the reflected wave. The processing unit 1B determines the presence or absence of an approaching object based on the output of the Doppler sensor 1A. The output signal from the Doppler sensor 1A to the processing unit 1B can be transmitted via wired or wireless transmission.

[0016] It is preferable that the Doppler sensor 1A, which is installed on the worker M's clothing Mw, be positioned on the back of worker M. This ensures that the transmission waves emitted by the Doppler sensor 1A are directed towards the back of worker M. Since the worker M of the brush cutter 10 works while facing forward and looking at the brush cutting work unit 13 equipped at the end of the extension of the operating rod 12, this placement of the Doppler sensor 1A allows for the transmission waves to be effectively directed towards the back of worker M while they are working.

[0017] Furthermore, it is preferable to position the Doppler sensor 1A above the connection point with the brush cutter 10 in order to avoid interference between the main body 11 of the brush cutter 10 and the transmitted waves emitted behind the worker M. In particular, as shown in Figure 1, it is preferable to install it at a high position on the garment Mw (near the shoulder of the worker M).

[0018] As a typical example of a wearable item to which the Doppler sensor 1A is attached, there is a harness including a back plate, a waist pad, a connector for connecting the mower 10, and a string-like member for connecting them to each other. When the Doppler sensor 1A is provided on such a harness, it is preferable to connect the Doppler sensor 1A to the back plate. This is because the back plate is composed of a resin frame or a resin surface, and it is easier to form an attachment portion for attaching the Doppler sensor 1A compared to other parts, and its fixation is stable.

[0019] As shown in FIG. 1, the direction of the Doppler sensor 1A is preferably arranged such that in the state where the operator M holds the handle 12A of the operating rod 12 and performs mowing work, the transmission direction of the transmission wave is substantially parallel to the ground. For this purpose, it is preferable to arrange the Doppler sensor 1A on the wearable item Mw such that the transmission wave is transmitted in a direction orthogonal to the rotation axis 13A of the mowing work unit 13. Further, since the reflected wave that hits the ground and returns becomes noise in detecting an approaching object, in order to suppress this, the direction of the Doppler sensor 1A is more preferably parallel to the ground or slightly upward with respect to that direction during mowing work.

[0020] In this way, by installing the Doppler sensor 1A on the wearable item Mw of the operator M and arranging it on the back side of the operator M, the detection range of the Doppler sensor 1A can be directed behind the operator M during mowing work, and the transmission wave can be effectively transmitted to the blind spot behind the operator M.

[0021] As shown in FIG. 2, in the mowing operation, the mowing operation unit 13 equipped at the tip of the operation lever 12 is swung left and right to perform the operation. Although the visual recognition range of the operator M also changes along with this swinging motion, since the transmission direction of the Doppler sensor 1A installed on the clothing Mw of the operator M always faces the back of the operator M and is transmitted, with respect to the back of the operator M, including those located in the blind spot range in particular, the presence or absence of approaching objects can be detected within a stable detection range. Also, by installing the Doppler sensor 1A on the clothing Mw of the operator M, the influence of the movement of the mower 10 during operation on the Doppler sensor 1A can be reduced, and the detection noise of the Doppler sensor 1A can be easily removed.

[0022] The function of the processing device 1B will be described with reference to FIG. 3. The output including the Doppler signal from the Doppler sensor 1A is signal-amplified by the signal amplification unit 20. This signal amplification unit 20 has, for example, a characteristic of having a high amplification factor for a relatively low frequency corresponding to the difference frequency between the transmission wave frequency and the reflection wave frequency, thereby improving the S / N ratio. The output of the signal amplification unit 20 is subjected to fast Fourier transform by the FFT calculation unit 21. In this FFT calculation unit 21, the intensity for each frequency of the output of the signal amplification unit 20 is obtained.

[0023] If necessary, the output of the FFT calculation unit 21 is subjected to noise removal by the noise removal unit 22. As shown in FIG. 2, when the operation lever 12 is swung left and right during the mowing operation, the Doppler sensor 1A installed on the clothing Mw of the operator M may move slightly due to the movement of the operator M, and the Doppler signal generated thereby is included as noise. In the noise removal unit 22, processing for removing such noise is performed.

[0024] At this time, by installing the Doppler sensor 1A on the clothing Mw of the operator M, the influence of the movement of the operator M on the Doppler sensor 1A can be reduced, and the noise removal process can be easily performed. In addition, by attaching a sensor for detecting movement to the clothing Mw of the operator M and performing noise processing taking into account the output of this sensor, more accurate noise processing can be performed.

[0025] The output signal, from which noise has been removed by the noise reduction unit 22, is then subjected to a determination process by the proximity determination unit 23 to determine whether or not there is an object approaching the brush cutter 10 within the detection range of the Doppler sensor 1A. If it is determined that there is an object approaching within the detection range, a signal to stop the operation of the brush cutter 10 is output to the control unit 1C.

[0026] The control unit 1C controls the drive unit of the brush cutter 10, and performs control to stop the drive unit of the brush cutter 10 according to the judgment output described above. If the drive unit of the brush cutter 10 is an engine, for example, it performs control to short-circuit the ignition primary circuit, and if the drive unit of the brush cutter 10 is an electric motor, for example, it performs control to cut off the power supply circuit to the electric motor.

[0027] The control unit 1C may not only control the drive unit of the brush cutter 10, but also control a notification device that alerts the operator M to the presence of an approaching object. The notification device may provide notification through, for example, a warning sound, vibration, or light display. When the control unit 1C controls the notification device, it controls the notification device in conjunction with the control unit.

[0028] Figure 4 shows the safety device 1 for a backpack-type brush cutter 10. The backpack-type brush cutter 10 uses a backpack frame 14 on which the main body 11 of the brush cutter 10 is carried as wearable clothing Mw by the operator M. By using the backpack frame 14 as wearable clothing Mw on which the Doppler sensor 1A of the safety device 1 is installed, the Doppler sensor 1A can be properly positioned facing the back of the operator M.

[0029] The backpack frame 14 is made of metal pipe or resin, and is advantageous in that it is easier to construct a mounting part for attaching the Doppler sensor 1A compared to other parts, and it can be fixed stably. In addition, since a vibration suppression member is interposed between the backpack frame 14 and the main body 11 of the brush cutter 10, by installing the Doppler sensor 1A on the backpack frame 14, it is possible to suppress the Doppler sensor 1A from being affected by the vibration of the main body 11.

[0030] As described above, the safety device 1 for a brush cutter according to the embodiment of the present invention enables the detection of objects approaching the brush cutter 10 while minimizing the impact of the operation motion of swinging the operating rod 12 of the brush cutter 10 from side to side, by placing the Doppler sensor 1A on the clothing Mw worn by the worker M operating the brush cutter 10. Furthermore, by positioning the Doppler sensor 1A on the back side of the worker M, the detection range of the Doppler sensor 1A can be directed to the blind spot behind the worker M, enabling effective detection of people or objects approaching the brush cutter 10 while it is in operation. This ensures the safety of people and objects around the brush cutter 10 while it is in operation.

[0031] Furthermore, the brush cutter 10 is equipped with a control unit 1C that, when the processing unit 1B determines that an object is approaching, stops the drive unit of the brush cutter 10 with an output from the processing unit 1B. Therefore, even if the user turns around and points the tip of the operating rod 12 towards an approaching object, the drive of the brush cutter 10 will be automatically stopped, thus preventing danger.

[0032] Although embodiments of the present invention have been described in detail above with reference to the drawings, the specific configurations are not limited to these embodiments, and any design changes, etc., that do not depart from the gist of the present invention are also included. Furthermore, the above-described embodiments can be combined by utilizing each other's technologies, as long as there are no particular contradictions or problems in their purpose and configuration. [Explanation of Symbols]

[0033] 1: Safety device, 1A: Doppler sensor, 1B: Processing unit, 1C: Control unit, 10: Brush cutter, 11: Main unit, 12: Operating rod, 12A: Handle, 13: Brush cutting unit, 13A: Rotating shaft, 14: Backpack frame, 20: Signal amplification section, 21: FFT calculation section, 22: Noise reduction unit, 23: Proximity detection unit, M: Worker, Mw: Clothing

Claims

1. A safety device for a brush cutter comprising a Doppler sensor installed in close proximity to the brush cutter during operation and a processing device that processes the output of the Doppler sensor, The Doppler sensor is installed on the wearable clothing of the operator operating the brush cutter, and is positioned to avoid interference between the transmitted waves, which are directed towards the operator's back, and the main body of the brush cutter connected to the wearable clothing. Furthermore, the orientation of the Doppler sensor is such that, when brush cutting is being performed, the direction of transmission of the transmitted waves is approximately parallel to the ground. The safety device for a brush cutter is characterized in that the processing device outputs a signal to stop the operation of the brush cutter when it detects a person or object approaching the brush cutter based on the output of the Doppler sensor.

2. The safety device for a brush cutter according to claim 1, characterized in that the wearable item is a harness including a connecting member for connecting to the brush cutter.

3. The safety device for a brush cutter according to claim 1, characterized in that the wearable item is a backpack frame for carrying the main body of the backpack-type brush cutter.

4. The brush cutter safety device according to claim 1, characterized in that the brush cutter is equipped with a control unit that receives the signal and stops the drive unit of the brush cutter.

Images