JP2015008693A - Engine work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine work machine which quickly stops an engine itself at the time of unstable attitude of the engine work machine.SOLUTION: An acceleration sensor is provided in a cylinder, and a control device controls the operation of an engine by using output of rotation detection means. Control means receives information from the acceleration sensor and the rotation detection means, excludes a range corresponding to predetermined frequency bands 75, 76 obtained by output of rotation detection means from an output 71 of the acceleration sensor, and suppresses or stops the operation of the engine when an acceleration peak 71a of a signal obtained from the excluded output is equal to or more than a prescribed threshold g.

Description

  The present invention relates to a small engine work machine using a small engine such as a brush cutter, a chain saw, a hedge trimmer, and the like, and particularly when the attitude of the work machine itself becomes unstable during engine operation, the engine is automatically stopped or output. The present invention relates to an engine work machine configured to suppress the above.

  In portable engine working machines such as a brush cutter, a chain saw, and a hedge trimmer, a cutting blade, a saw chain, and the like are driven through a centrifugal clutch mechanism in which the output of the engine is directly or indirectly connected to a crankshaft. Centrifugal clutches are clutches that transmit power by the frictional force of a clutch shoe provided on the rotating body side such as a crankshaft and a clutch drum provided on the driven side and provided on the outer peripheral side of the clutch shoe. Since the centrifugal force is small during low speed rotation such as in a state, the clutch shoe is located on the inner peripheral side, and the power of the rotating body is not transmitted to the driven side (clutch disengaged state). When the engine speed rises and exceeds a predetermined speed (clutch connection speed), the clutch shoe moves to the outer peripheral side by centrifugal force and comes into contact with the inner peripheral surface of the drum to be driven from the rotating body. Power is transmitted to the clutch (clutch connected state). In such a centrifugal clutch mechanism, when the engine speed increases, the clutch mechanism is automatically connected and the cutting blade rotates, so that the cutting blade, saw chain, etc. can be removed for some reason during the operation of the portable engine work machine. Even if you want to stop, you can't disconnect the clutch until the engine speed drops.

  For this reason, it has been proposed to provide a mechanical brake device together with the adoption of a centrifugal clutch in an engine working machine. As such a brake device, there exists a thing shown by patent document 1, for example. In this brake device, as disclosed in FIG. 6, a brake shoe is disposed in contact with the outer periphery of the brake drum, a brake wire is stretched between the brake shoe and the arm, and the brake wire is attached by a brake spring. In addition to pulling back, the brake shoe is pressed against the brake drum. When the arm is not operated, the brake shoe is pressed by a brake spring, and the brake acts on the brake drum.

JP 2002-186327 A

  In the structure of Patent Document 1, although the work device can be quickly stopped using the brake, the engine speed only returns to the idling speed. When you want to stop the cutting blade, saw chain, etc., you may want to stop the engine quickly, for example, when the operator loses the working posture and becomes unstable or when the engine work machine is dropped. is there.

  The present invention has been made in view of the above background, and the purpose of the present invention is when an unstable posture occurs such as when an operator breaks his working posture into an unstable situation or when an engine work machine is dropped. An object of the present invention is to provide an engine working machine that can quickly suppress or stop rotation of an engine.

  Another object of the present invention is to provide an engine working machine that uses an acceleration sensor and an engine rotation detection means to suppress or stop the rotation of the engine when an abnormality occurs.

  Still another object of the present invention is to provide an engine work machine in which a pressure sensor is provided in a grip portion gripped by an operator, and the rotation of the engine is suppressed or stopped at the time of abnormality using a signal of the pressure sensor. It is to provide.

  The characteristics of representative ones of the inventions disclosed in the present application will be described as follows.

  According to one aspect of the present invention, an engine working machine that operates a working machine with an engine having a case and a crankshaft extending through the crankcase, the acceleration sensor provided in the cylinder or the crankcase, the crank A rotation detection means for detecting the rotation of the shaft and a control means for controlling the operation of the engine are provided. The control means receives information from the acceleration sensor and the rotation detection means, and is obtained from the output of the acceleration sensor by the output of the rotation detection means. The range corresponding to the frequency band is excluded, and the operation of the engine is suppressed or stopped when the acceleration peak of the signal obtained from the excluded output is equal to or greater than the threshold value. As described above, since the acceleration signal obtained from the acceleration sensor, the peak frequency of the acceleration signal, the engine speed obtained from the rotation detecting means, and the engine frequency are used as parameters for detecting the unstable situation, the engine operation is performed. The unstable situation of the machine can be detected effectively.

  According to another feature of the invention, the excluded frequency bands are bands with a predetermined width of plus and minus around the natural frequency of the engine determined by the output of the rotation detecting means. Further, the control means obtains the nth order frequency of the engine based on the information obtained by the rotation detection means, and not only the first order frequency but also a band with a predetermined positive and negative width centered on the nth order frequency. Since it is excluded from the output, it is possible to effectively detect an unstable state of the engine work machine such as unbalance without being affected by the fundamental vibration of the engine. Further, the control means uses a different threshold value for each engine speed region, and this threshold value is stored in advance in a storage device in the control device. For this reason, since it is only necessary to read out the threshold value corresponding to the engine speed from the storage device, the required processing capacity of the microcomputer is low. Further, the control means obtains an impact peak from the output of the acceleration sensor, and suppresses or stops the operation of the engine when the acceleration peak is equal to or greater than the threshold value and the impact peak is equal to or greater than the threshold value. If the control is performed, an unstable situation can be detected with higher accuracy.

  According to another feature of the present invention, a pressure sensor for detecting a gripping state by the worker is provided in a grip portion gripped by the worker, and the control means detects the gripping state by the worker based on an output from the pressure sensor, The engine peak is detected using the acceleration peak and the output from the pressure sensor, and the engine operation is suppressed or stopped. Situation detection can be performed.

  According to the present invention, it is possible to effectively detect an engine peak without being influenced by engine vibration by effectively detecting an acceleration peak in a frequency region that is out of a frequency region in which a specific acceleration peak derived from a work machine and a work operation appears. The unstable situation of the machine can be detected effectively. Moreover, the case where the attachment state of a cutting blade is abnormal can be detected effectively.

1 is a perspective view of an engine working machine according to an embodiment of the present invention. FIG. 2 is a rear view of the engine 10 of FIG. 1 and shows a state where a cylinder cover 7 is removed. It is a side view of the engine 10 of FIG. FIG. 1 is vibration measurement data detected during normal operation of the engine work machine of FIG. 1, where (1) is a change in acceleration in the vertical direction, (2) is a change in acceleration in the front-rear direction, and (3) is a change in left-right direction. Indicates the change in acceleration. FIG. 1 is vibration measurement data when the engine work machine of FIG. 1 is freely dropped in the vertical direction, where (1) is a change in acceleration in the vertical direction, (2) is a change in acceleration in the front-rear direction, and (3) is Indicates the change in acceleration in the left-right direction. FIG. 1 shows vibration measurement data when the engine work machine in FIG. 1 receives a kickback, where (1) is a change in acceleration in the vertical direction, (2) is a change in acceleration in the front-rear direction, and (3) is a horizontal direction. Shows the change in acceleration. It is the measurement data of a vibration when the cutting blade of the engine working machine of FIG. 1 is made into an unbalanced state. It is a comparison data of the vibration when the cutting blade of the engine working machine of FIG. 1 is put in an unbalanced state. It is a flowchart which shows the procedure of the engine automatic stop control using the acceleration sensor and rotation detection means in a present Example. FIG. 9 is a modified example of the flowchart of FIG. 9 in which the frequency range based on the engine order is calculated based on the engine speed obtained by the rotation detecting means, and the influence of the engine vibration is excluded by excluding the data in this frequency range from the acceleration information. It is a flowchart which shows an example of the control procedure which adds control to perform. FIG. 10 is a modified example of the flowchart of FIG. 9, and is a flowchart illustrating an example of a control procedure for adding control for setting a threshold value corresponding to engine speed information obtained from the rotation detection unit. FIG. 10 is a modified example of the flowchart of FIG. 9, and is a flowchart illustrating an example of a control procedure for adding a comparison between an impact peak that can be calculated from acceleration information and a threshold value as a determination criterion for an unstable situation. FIG. 10 is a modified example of the flowchart of FIG. 9 and is a flowchart illustrating an example of processing of a controller for control to add pressure information from the pressure sensor.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same portions are denoted by the same reference numerals, and repeated description is omitted. Further, in the present specification, description will be made assuming that the front and rear directions and the up and down directions are directions shown in the drawing.

  FIG. 1 is a perspective view showing the overall shape of a brush cutter as an example of the engine working machine 1. The engine working machine 1 includes an engine 10 (an engine body serving as a driving unit) attached to one end of the main pipe 4 and a rotating cutting blade (rotating blade) 2 attached to the other end side of the main pipe 4. The cutting blade 2 can be attached to and detached from a spindle (not shown) provided in the gear unit, and in the vicinity of the cutting blade 2, a scattering protection cover 3 for preventing scattering of the cut grass is provided. The handle 5 is assembled slightly behind the middle of the main pipe 4 in the longitudinal direction. An engine 10 is provided on the rear end side of the main pipe 4. The engine working machine 1 uses a general-purpose engine that is small and light and can obtain a large output, and replenishes fuel to enable long-time work. In order to start the engine 10, for example, a manual starter is widely used.

  The handle 5 is a metal pipe having a substantially U-shape when viewed from the front, and is provided with resin grip portions 6a and 6b at the distal end portion. A throttle lever 34 and a lock lever 35 are provided in the vicinity of the base of the grip portion 6a on the side gripped by the operator with the right hand, and the operator operates the throttle lever 34 while pulling the lock lever 35 to rotate the engine 10. The rotational speed of the cutting blade 2 is adjusted by adjusting the number. Furthermore, the pressure sensor 38 is provided in the grip part 6a. The pressure sensor 38 is provided at a position where a predetermined pressure is applied to the pressure sensor 38 when the operator grips the grip portion 6a. By monitoring the output signal of the pressure sensor 38, the operator holds the grip portion 6a. Whether it is gripped or released can be detected.

  The operator performs work while holding the pressure sensor 38. The cable 39 for throttle has a wire disposed on the inner side (inner) and the outer side (outer) covered with a resin cover, and the cable 39 is a throttle of the carburetor 20 (see FIG. 2) described later. Connected to the mechanism. When the throttle lever 34 is pulled, a wire (described later) arranged inside the cable 39 is pulled toward the handle, and the throttle of the carburetor 20 described later is opened. When it is determined by the pressure sensor 38 that the operator is not gripping the grip portion 6a, the control procedure according to the present embodiment is executed by the control device described later. The control will be described later.

  FIG. 2 is a rear view of the engine 10 of the engine working machine 1 according to the present embodiment, and shows a state in which the cylinder cover 7 (see FIG. 1) is removed. The engine 10 is a two-cycle small engine, a crankshaft (not shown) is disposed coaxially with the main pipe 4 (see FIG. 1), and a cylinder 11 is disposed so as to extend substantially upward from the crankcase 14. In FIG. 11, a piston (not shown) reciprocates up and down. A recoil starter 30 for starting the engine is provided on the rear end side of the crankshaft (the end opposite to the side where a centrifugal clutch (not shown) is disposed). The recoil starter 30 is attached to the crankcase 14 by four screws 33. The recoil starter 30 is a manual starter, and an operator starts the engine 10 by rotating the crankshaft by strongly pulling the starter handle 31 when the engine 10 is started. Since the configuration of the recoil starter 30 itself is the same as that of the conventional example, a detailed description thereof is omitted here. A carburetor 20 is provided on the left side of the engine 10 via an insulator 22 connected to an intake port, and an air cleaner cover 21 that constitutes a storage space for an air cleaner that filters inhaled air outside the carburetor 20 (left side). Is provided.

  A muffler 16 is provided on the side (right side) of the engine 10, and an exhaust port 16 a serving as an exhaust gas outlet is provided on the rear surface side of the muffler 16. The muffler 16 is covered with a resin muffler cover 15 to prevent the operator from touching it directly. The upper part of the engine 10 is covered with a cylinder cover 7 (see FIG. 1). A fuel tank 27 is provided below the crankcase 14. The fuel tank 27 is a container formed of a translucent polymer resin, and a mixed fuel in which gasoline and a predetermined ratio of oil are mixed can be put in by removing the cap 28 attached to the opening. When starting the engine 10, the operator pulls the choke lever (not shown) and then pulls the starter handle 31 vigorously to start the engine 10.

  In this embodiment, an acceleration sensor 37 is provided near the lower end of the cylinder 11 and in the vicinity of the attachment surface to the crankcase 14 as a sensor for picking up the acceleration of the engine 10. If the acceleration sensor 37 is provided at the position shown in the figure, the vibration of the cylinder 11 is directly detected and it seems that noise increases. However, the noise from the cylinder 11 due to the operation of the engine 10 is controlled by the control of this embodiment. When removing, it is better to attach the acceleration sensor 37 to the cylinder 11 which can be said to be a generation source of vibration. The position where the acceleration sensor 37 is provided is not provided so as to be in contact with the cylinder 11 but may be attached so as to be in contact with the crankcase 14 or may be provided in a place other than the cylinder 11 and the crankcase 14. Also good.

  The signal of the acceleration sensor 37 is transmitted to a control device (controller) 36 provided inside the case of the recoil starter 30 via a cable (not shown), and the control device 36 performs signal processing. The control device 36 is preferably configured to include a general-purpose microcomputer (microcomputer), and performs signal analysis (to be described later) by executing a predetermined program by the microcomputer, and controls the operation of the engine 10 based on the result of the analysis processing (engine The engine speed is returned to idling) or the engine 10 is stopped. still. The position where the control device 36 is provided is not limited to the case portion of the recoil starter 30 but may be provided in the cylinder cover 7 or other parts.

  FIG. 3 is a side view of the engine 10. The high-voltage current generated by the ignition coil 23 is transmitted to the ignition plug 26 (see FIG. 2) via the ignition cord 24 and the plug cap 25. A magnet rotor 17 is provided at the front end of the crankshaft (not shown) of the engine 10. The magnet rotor 17 is a part that functions as a flywheel that stabilizes the motion of the rotating mechanism. In the engine 10 of this embodiment, the magnet rotor 17 is cooled to cool the cylinder 11. Fins 17a for generating wind are integrally formed, and a magnetized magnetic body (magnet) 18 is provided on a part of the outer peripheral surface of the magnet rotor 17 to generate a high-voltage current for ignition. . The magnet rotor 17 is integrally formed with the fins 17a, for example, by casting an aluminum alloy, and is fixed to the crankshaft by bolts or the like. A centrifugal clutch 19 is provided on the front side of the magnet rotor 17. When the rotational speed of the engine 10 is equal to or lower than the connection rotational speed of the centrifugal clutch 19, the clutch drum (not shown) is engaged with a clutch pawl provided on the magneto rotor 17. Is removed, power transmission to the tip tool is interrupted, and the cutting blade 2 as the tip tool stops. A volute case 8 is provided on the front side of the centrifugal clutch. The volute case 8 is formed integrally with the leg portion 9 and rotatably supports a drum portion (not shown) of the centrifugal clutch 19.

  Near the lower end of the air cleaner cover 21, a primary pump 32 is provided for sucking the mixed fuel from the fuel tank 27 to the carburetor 20 immediately before starting. An operator sucks fuel into the carburetor 20 by repeatedly pressing the primary pump 32 immediately before starting the engine 10. The primary pump 32 is a hemispherical transparent valve, and it can be visually confirmed that the fuel has reached the vaporizer 20 when the mixed fuel has reached the transparent valve portion.

  Next, vibration measurement data of the engine 10 detected during normal operation of the engine work machine 1 will be described with reference to FIG. This data is a signal detected based on the output signal of the acceleration sensor 37 provided in the vicinity of the lower end of the cylinder 11. The horizontal axis represents the vibration frequency (Hz) and the vertical axis represents the acceleration (G). In this embodiment, it is detected by an acceleration sensor 37 that can detect vibrations about three axes, and the magnitude of the measured vibration acceleration varies depending on the rotational speed of the engine 10. In FIG. 4, an acceleration signal (shown by solid lines 41 to 43) when the engine speed is 10,000 rpm and an acceleration signal (shown by dotted lines 46 to 48) when the engine speed is 8000 rpm were measured. FIG. 4 (1) shows the change in acceleration in the vertical direction during normal operation. At 10000 rpm, two peak vibrations near the arrow 41a and the arrow 41b appear. This peak vibration is an engine speed of 10,000 rpm, that is, about 166 Hz and its secondary frequency (about 333 Hz). At 8000 rpm, peak vibrations appear at two locations, and the peaking frequencies as indicated by arrows 46a and 46b decrease with decreasing engine speed and appear at about 133 Hz and 267 Hz.

  FIG. 4 (2) shows a change in acceleration in the front-rear direction during normal operation. At 10000 rpm, two peak vibrations appear in the vicinity of the arrow 42a and the arrow 42b. At 8000 rpm, the point where the peak vibration appears is one point indicated by an arrow 47a. FIG. 4 (3) shows the change in acceleration in the left-right direction during normal operation. At 10000 rpm, two acceleration peaks near arrow 43a and arrow 43b appear. At 8000 rpm, there are almost no points at which peak vibrations appear, but the acceleration near the arrow 48a is relatively high. As can be understood from the waveforms of (1) to (3), the position where the peak vibration appears is greatly affected by the engine speed and the direction of vibration, so a predetermined bandwidth near the peak position according to the engine speed. It is possible to detect whether or not the attitude of the engine work machine 1 is in an unstable state by removing a signal (for example, a frequency band near ± 5 to 20 Hz) and performing analysis using other signals.

  Next, vibration measurement data of the engine 10 detected when the engine work machine 1 is dropped during work will be described with reference to FIG. These data are also detected by the output signal of the acceleration sensor 37. The frequency band shown here is the acceleration signal acquired during the fall when the engine work machine 1 is freely dropped during the work at the engine speed of 10,000 rpm. As a characteristic vibration, a low-frequency characteristic vibration is generated. Here, the horizontal axis plots 0 to 64 Hz, but the portion that is a peak signal (indicated by an arrow 51a. The symbol “□” indicates the position where the acceleration is a peak among the plurality of peaks 51a to 51d. In the following, the detection frequency f of the peak at the time of falling is about 2 Hz as indicated by the arrow 51a in the vertical direction, 1 Hz or less as indicated by the arrow 52a in the front-back direction, and 1 Hz or less as indicated by the arrow 53a in the left-right direction. is there. The frequency (engine frequency fe) due to vibration based on the engine speed at the time of the fall is as shown in FIG. 4. For example, when viewed from the acceleration signal at 10000 rpm, the detected frequency f of the arrows 51 a, 52 a, 53 a 4 does not coincide with the arrows 41a, 42a and 43a of FIG. This comparison is the same even when compared with the acceleration signal at 8000 rpm, and the detection frequency f of the arrows 51a, 52a, 53a and the arrow 46a, 47a, FIG. It does not match 48a. Compared with the acceleration peak appearing in FIG. 4, the arrow 51a is about several g, and even the acceleration peaks near the arrows 52a and 53a are about 1 to 3 g.

  Next, vibration measurement data of the engine 10 that is detected when the posture of the engine work machine 1 is suddenly changed due to the influence of kickback or the like during work will be described with reference to FIG. A characteristic vibration particularly detected at the time of kickback is that it is widely distributed to about 0 to 100 Hz, unlike the acceleration signal obtained at the time of dropping shown in FIG. Here, the horizontal axis plots 0 to 128 Hz, but in the portion that becomes the peak signal, the detection frequency f at the kickback is about 3 Hz as indicated by the arrow 61a in the vertical direction and as indicated by the arrow 62a in the front and rear direction. About 4 Hz and about 4 Hz in the left-right direction as indicated by an arrow 63a. Compared to acceleration due to natural vibration (engine frequency fe) based on the engine speed at the time of kickback, the detection frequency f indicated by arrows 61a, 62a, 63a, etc. in FIG. It is in a region that does not coincide with the arrows 41a, 42a, 43a of FIG.

  Next, vibration measurement data of the engine 10 detected when the cutting blade 2 is mounted eccentrically and the engine work machine 1 is in an unbalanced state will be described with reference to FIGS. As characteristic vibrations that are particularly detected when an unbalanced state is reached, the waveform shown in FIG. 4 is almost the same as the signal shown in FIG. 7A when viewed in the vertical direction. Looks the same. For example, in the acceleration 71 at 10000 rpm, two peaks (arrows 71a and 71b) appear as in the acceleration 41 in the figure. However, when viewed in the front-rear direction, only one acceleration peak can be seen as shown by an arrow 72a as shown in FIG. Also, only one acceleration peak can be seen in the left-right direction as shown by an arrow 73b. In this way, when the engine working machine 1 is in an unbalanced rotation state due to some factor or external factor, the waveform of the output signal of the acceleration sensor 37 becomes larger or smaller, and the peak signal is in a specific direction. Or shift. Here, the acceleration signal 41 in FIG. 4A and the acceleration signal 71 in FIG. 7A will be further described with reference to FIG.

FIG. 8 is a graph in which the acceleration signal 41 in FIG. 4A and the acceleration signal 71 in FIG. 7A (both engine speeds are 10,000 rpm) are arranged in the same graph. What can be seen here is that the acceleration signal 71 overall increases in an unbalanced state as compared with the acceleration signal 41 in the normal state, and the acceleration peak shifts in the direction of increasing from the arrow 41a to the arrow 71a. Similarly, the acceleration peak of the arrow 41b is shifted in the direction of increasing as indicated by the arrow 71b. Here, in the present embodiment, the engine frequency f ₁ resulting from the rotation speed of the engine 10 is calculated based on the real-time engine rotation speed obtained from the rotation detection means that detects the rotation of the engine (crankshaft). The mask range 75 within a predetermined range (here, f ₁ ± 15 Hz) from the engine frequency f ₁ is excluded from the detected acceleration signal, and the acceleration peak 71a has a predetermined threshold in a frequency region other than the mask range 75. whether exceeds the value g ₁ are compared. Here, the relationship between the engine speed and the engine frequency f ₁ may be calculated in advance before product shipment and stored in a microcomputer or memory included in the control means. Here, compared to the threshold value g ₁ peak value of the detection frequency f in the entire frequency region other than the mask range 75 (acceleration peak g) is set in advance, the engine working machine 1 if the threshold value g ₁ below it is determined to be working in a normal state, determining that the acceleration peak g is if exceeding the threshold value g _1, which is the state of the abnormality that need to drop to or idling speed to stop the engine 10 To do. 8 has been described in example comparing acceleration only in the vertical direction, similarly to compare the acceleration peak g and threshold g ₁ which is measured also in the acceleration signal in the front-rear direction and the lateral direction, either of when the acceleration signal exceeds the threshold value g _1, may be determined that the state of the abnormality that need to drop to or idling speed to stop the engine 10.

The mask range excluded from the acceleration signal is not limited to the mask range 75 that is the fundamental frequency (primary frequency) of the engine 10, but is also a predetermined range above and below the f2 that is the _second harmonic frequency of the engine 10 (here, f ₂ ± 15 Hz) may be excluded from the acceleration signal 71 to be compared as the mask range 76. The mask range may be set in the nth harmonic frequency region (n = 2, 3,...) As necessary. The width of the mask range is about ± 15 Hz here, but this width may be set as appropriate according to the type of engine, the vibration characteristics, the mounting position of the acceleration sensor, the mounting direction, and the like. If comprised in this way, the influence of the harmonic component of the vibration frequency of an engine can be excluded effectively.

Next, the processing procedure of the automatic stop control of the engine 10 using the acceleration sensor and the rotation detection means will be described using the flowchart of FIG. The control device 36 first acquires acceleration information by obtaining the output of the acceleration sensor 37 (step 81). Next, the control device 36 detects an acceleration peak g in the vertical direction, the front-rear direction, and the left-right direction from the obtained acceleration signal, and calculates a detection frequency f of the acceleration peak g (step 82). Next, the control device 36 detects the rotational speed of the engine 10 using the output of the ignition coil 23, captures the information (step 83), and the engine frequency at which the vibration caused by the rotational speed of the engine 10 peaks. fe is calculated (step 84). Next, the control device 36 determines whether or not the detected detection frequency f matches the engine frequency fe (step 85). Whether or not they match is not a comparison of whether or not the frequencies exactly match, and the engine frequency fe is given a certain width. For example, when the engine speed is 10,000 rpm, the inherent engine frequency fe is 166 Hz. Therefore, a range having a width centered at 166 Hz (for example, ± 15 Hz), for example, a range of about 151 to 181 Hz is set as the engine frequency fe, and whether or not the detection frequency f is included in the range is determined to match. judge. Here, if it is determined that they coincide with each other, it is considered that the detection frequency f is not due to an abnormality such as a fall, so the process returns to step 81. If it is determined that they do not coincide, the acceleration peak g at the detection frequency f is reduced. It is determined whether or not the threshold value g is ₁ or more (steps 85 and 86). In step 86, if the acceleration peak g is determined threshold value g ₁ or more, the control unit 36 so as to actuate the safety device (not shown) and drops to or idling speed to stop the engine 10 (step 86, 87). The safety device can be realized even if the kill switch is electronically turned on or off by, for example, the control device 36 executing a program. In step 86, the acceleration peak g in the sensing frequency f if less than the threshold value _{g 1,} the flow returns to step 81. According to the processing of the present embodiment, it is possible to prevent the acceleration derived from the vibration of the engine 10 from being erroneously determined as the acceleration peak in an unbalanced state, and thus an unbalanced unbalance can be reliably ensured regardless of the engine speed. There is an effect that a stable situation can be detected effectively.

  Next, a modification of the present embodiment will be described using the flowchart of FIG. In the procedure of FIG. 10, the frequency range by the engine order is calculated based on the engine speed obtained by the rotation detecting means, and the control of excluding the influence of the engine vibration by excluding the data in this frequency range from the acceleration information first. Is added. The control device 36 first detects the rotational speed of the engine 10 using the output of the ignition coil 23 and captures the information (step 91). Next, the control device 36 calculates the engine frequency fe of vibration caused by the rotational speed of the engine 10 and the n-th order frequency fn of the engine 10 (steps 92 and 93). Next, the control device 36 captures acceleration information by obtaining the output of the acceleration sensor 37 (step 94), and based on the obtained acceleration signal, a band in the vicinity of the engine frequency fe and the n-th frequency fn of the engine 10 is obtained. The acceleration signal in the signal range of (± 15 Hz) is excluded. Here, it is only necessary to exclude the signal of n = 1 (that is, the engine frequency fe) and the engine frequency f2 of n = 2, but the configuration is such that the acceleration signal in the signal region of n = 3, 4,. You may do it. Further, the bandwidth to be excluded is not limited to ± 15 Hz, but may be determined as the optimum bandwidth for the detection operation according to the present embodiment. Furthermore, since it is not necessary to make the bandwidths of n = 1 and n = 2 the same, the bandwidth of n = 1 may be set wider or narrower than the bandwidth of n = 2.

Next, in the excluded frequency range in step 96, the vertical direction, whether longitudinal direction, detects the acceleration peak g in the horizontal direction (step 96), its acceleration peak g is a predetermined threshold value g ₁ or more Is determined (step 97). If the acceleration peak g is determined threshold value g ₁ or more, the control unit 36 so as to actuate the safety device (not shown), or stops the engine 10 or drop in idling speed (step 97, 98) . As described above, according to the modification of the present embodiment, the acceleration signal in the vicinity of the nth-order frequency fn of the engine 10 is removed, so that the engine-specific vibration is regarded as vibration caused by an unstable state of the engine work machine. Can be distinguished effectively. In the modification of FIG. 10, a range corresponding to a predetermined frequency band obtained from the output of the rotation detecting means is excluded from the output of the acceleration sensor according to the rotational speed of the engine 10, and the acceleration peak is calculated from the remaining frequency range. Therefore, it is possible to reliably prevent the acceleration peak appearing in the vicinity of the natural frequency of the engine 10 from being detected.

FIG. 11 shows a second modification of FIG. 9 and is a flowchart for explaining a procedure in which control for setting a threshold value corresponding to engine speed information obtained from the rotation detecting means is added. The control device 36 detects the rotational speed of the engine 10 using the output of the ignition coil 23, and takes in the information (step 101). Next, the control unit 36 obtains the engine frequency fe of the vibration caused by the rotational speed of the engine 10 (step 102), determines the acceleration peak threshold _{g 1} corresponding to the rotational speed of the engine 10 (step 103) . This threshold g ₁ may store in the storage means (not shown) of the control device 36 in advance set before shipment, threshold g corresponding to the rotational speed from the memory means during the process of step 103 ₁ should be read out. Further, the threshold value g ₁ may be calculated by a predetermined function corresponding to the engine speed, and the control device may be calculated by calculating the function during the processing of step 103. May be.

Next, the control device 36 acquires acceleration information by obtaining the output of the acceleration sensor 37 (step 104). Next, the control device 36 detects the acceleration peak g in the vertical direction, the front-rear direction, and the horizontal direction from the obtained acceleration signal, and calculates the frequency (detection frequency f) of the acceleration peak g (step 105). Next, the control device 36 determines whether or not the detected frequency f matches the engine frequency fe (step 106). Whether or not they match is not a strict comparison of whether the frequencies are the same, but the comparison with a predetermined bandwidth is the same as the processing procedure in FIG. Here, if it is determined that they match, it is considered that the acceleration peak is not caused by an abnormality such as a fall, so the process returns to step 101. If it is determined that they do not match, the acceleration detection frequency f is a threshold value. g It is determined whether or not ₁ (steps 106 and 107). In step 107, if the acceleration peak g in the sensing frequency f is determined threshold value g ₁ or more, the control unit 36 so as to actuate the safety device (not shown), or the idling rotation speed to stop the engine 10 (Steps 107 and 108). In step 107, the acceleration peak g If there is less than the threshold value _{g 1,} the flow returns to step 101 (step 107). As described above, according to the second modification of this embodiment, in order to set the threshold g ₁ according to the rotation speed of the engine 10, all speed range (e.g., centrifugal clutch which performs the actual work It is possible to effectively detect the unstable state of the engine work machine at the connected rotation speed). As a result, it is possible to prevent the occurrence of a phenomenon in which an unstable situation can be detected only in a certain rotation speed range. Further, the resulting unbalanced state, even when a small acceleration peak than the normal engine vibration has appeared. Thus appropriately changed according to the threshold g ₁ to the rotational speed, effect Unstable state can be detected.

FIG. 12 shows a third modification example of FIG. 9, and shows a processing procedure for controlling the control device 36 to add a comparison between the impact peak that can be calculated from the acceleration information and the threshold value g ₁ to the determination criterion of the unstable situation. It is a flowchart which shows an example. The control device 36 acquires acceleration information by obtaining the output of the acceleration sensor 37 (step 111), detects peaks in the vertical direction, the front-rear direction, and the left-right direction from the obtained acceleration signal, and detects the acceleration peak g and the detection frequency. f, Impact peak G is calculated (step 112). Next, the control device 36 detects the rotational speed of the engine 10 using the output of the ignition coil 23, captures the information (step 113), and obtains the engine frequency fe of the vibration caused by the rotational speed of the engine 10 (step 113). 114). Next, the control device 36 determines whether or not the detected detection frequency f coincides with a band including the engine frequency fe (step 115). Here, if it is determined that the detection frequency f is included in the band including the engine frequency fe, it is considered that the detection frequency f is not the detection frequency f due to an abnormality such as a fall, so the process returns to step 111 and is determined not to match. If the acceleration peak g in the sensing frequency f is determined whether a threshold value _{g 1} or more (step 115, 116). In step 116, if the acceleration peak g is determined threshold value g ₁ or more, then the impact peak G is equal to or larger than the threshold value (step 117). Here, the impact peak G can be obtained by the following equation.
_{G = m (g t - g} t-1)
Where m is the weight of the engine working machine
g _t : acceleration signal at time t
That is, the impact peak G can be calculated as the amount of change in acceleration per unit time. When the impact peak G is greater than or equal to the threshold value, the control device 36 operates a safety device (not shown) to 10 is stopped or decreased to the idling speed (steps 117 and 118). If the impact peak G is less than the threshold value in step 117, the process returns to step 111 (step 117).

  As described above, in the third modified example, since the impact peak G is used in addition to the acceleration peak g, it is ensured that the engine working machine has fallen into an unbalanced state without being affected by the engine speed. Can be detected. In the third modification, the impact peak G is calculated from the output of the acceleration sensor 37. However, an impact sensor is provided separately from the acceleration sensor 37, and an unstable posture is also obtained using the waveform of the output signal. You may comprise so that it may detect. The position where the impact sensor is provided in this case is arbitrary, but it is preferable that the impact sensor be provided on the most projecting portion of the engine work machine 1 or a portion sufficiently away from the center of gravity, such as a cover of a recoil starter.

FIG. 13 is a flowchart showing a control processing procedure for adding pressure information from the pressure sensor, which is a fourth modification of FIG. In FIG. 13, first, the control device 36 determines whether or not the output signal from the pressure sensor 38 exceeds a threshold value 1, which is a predetermined pressure value (step 121). If so, the control device 36 acquires the acceleration information by obtaining the output of the acceleration sensor 37 (step 122), and detects the acceleration peak g in the vertical direction, the front-rear direction, and the left-right direction from the obtained acceleration signal. Then, the detection frequency f at that time is calculated (step 123). Next, the control device 36 obtains an engine frequency fe of vibration caused by the rotational speed of the engine 10 (step 124). Next, the control device 36 determines whether or not the detected detection frequency f is within a predetermined bandwidth from the engine frequency fe, that is, whether they match (step 125). Here, if it is determined that they match, it is considered not to be the acceleration peak g due to an abnormality such as a fall, so the process returns to step 121. If it is determined that they do not match, the acceleration peak at the detection frequency f is the threshold. determining whether the value _{g 2} or more (step 126, 126). In step 85, if the acceleration sensing frequency f is determined as a threshold g ₂ or more, the control unit 36 so as to actuate the safety device (not shown) and drops to or idling speed to stop the engine 10 (Steps 126 and 127). In step 126, the acceleration detection frequency f if less than the threshold value _{g 2,} the flow returns to step 121 (step 126).

In step 121 of FIG. 13, when the output signal from the pressure sensor 38 does not exceed the threshold value 1 which is a predetermined pressure value, the procedure of steps 132 to 136 is executed. Wherein the procedure of step 132-136 are the same as steps 122 to 126 is the threshold _{g 3} used in step 136 different. Threshold g _3, when the operator does not grip the grip portion 6a, for example, is set in a range that exceeds when had dropped the engine working machine for some reason such as falling, the engine as such when the working machine is not the normal state of use, that is, in the use state of the abnormality can be reliably detects the abnormal state by using a dedicated threshold g _3.

  As mentioned above, although this invention was demonstrated based on the Example, this invention is not limited to the above-mentioned Example, A various change is possible within the range which does not deviate from the meaning. For example, in the above-described embodiment, the brush cutter is used as an example of the engine working machine. However, the operator moves not only to portable engine working machines such as chain saws and hedge trimmers but also to engine working machines that cannot be carried. The present invention can be similarly applied to an engine working machine such as a cultivator that is used while being used.

1 Engine working machine 2 Cutting blade (rotating blade)
3 Splash protection cover 4 Main pipe 5 Handle 6a, 6b Grip part 7 Cylinder cover 8 Volute case 9 Leg part 10 Engine 11 Cylinder 13 Throttle lever 14 Crank case 15 Muffler cover 16 Muffler 16a Exhaust port 17 Magnet rotor 17a Fin 18 Magnetic body 19 Centrifugal clutch 20 Vaporizer 21 Air cleaner cover 22 Insulator 23 Ignition coil 24 Ignition cord 25 Plug cap 26 Spark plug 27 Fuel tank 28 Cap 30 Recoil starter 31 Starter handle 32 Primary pump 33 Screw 34 Throttle lever 35 Lock lever 36 Controller 37 Acceleration sensor 38 Pressure sensor 39 Cables 41-43, 46-48 Acceleration signals 51-53, 61-63 71-73 acceleration signal 75 mask range (basic frequency)
76 Mask range (secondary frequency)
g Acceleration peak f Detection frequency G Impact peak fe Engine frequency (primary)
f2 Engine frequency (secondary)
fn Engine frequency (nth order)

Claims (7)

An engine working machine that operates a working machine with an engine having a cylinder in which a piston can reciprocate, a crankcase that holds the cylinder and forms a crank chamber, and a crankshaft that extends through the crankcase,
An acceleration sensor provided in the cylinder or the crankcase;
Rotation detecting means for detecting rotation of the crankshaft;
Providing a control means for controlling the operation of the engine;
The control means includes
Receiving information from the acceleration sensor and the rotation detecting means;
Excluding a range corresponding to a predetermined frequency band obtained by the output of the rotation detection means from the output of the acceleration sensor,
An engine work machine characterized by suppressing or stopping operation of the engine when an acceleration peak of a signal obtained from the excluded output is equal to or greater than a threshold value.   2. The engine working machine according to claim 1, wherein the frequency band is a band having a predetermined width of plus and minus centering on a natural frequency of the engine obtained by an output of the rotation detecting unit. The control means obtains the nth order frequency of the engine based on the information obtained by the rotation detection means,
3. The engine working machine according to claim 1, wherein a band having a predetermined positive and negative width centered on the n-th order frequency is excluded from the output of the acceleration sensor. 4.   The engine working machine according to claim 3, wherein the control means uses a different threshold value for each engine speed range.   The engine working machine according to claim 4, wherein a threshold value set for each engine speed region is stored in advance in a storage device in the control means.   The control means obtains an impact peak from the output of the acceleration sensor, and suppresses the operation of the engine when the acceleration peak is not less than the threshold value and the impact peak is not less than the threshold value. Alternatively, the engine working machine according to any one of claims 1 to 5, wherein the engine working machine is stopped. A pressure sensor for detecting the gripping state by the worker is provided in the grip portion gripped by the worker,
The control means detects a gripping state by an operator based on an output from the pressure sensor,
The operation of the engine is suppressed or stopped by detecting that the posture of the engine working machine is unstable using the acceleration peak and an output from a pressure sensor. The engine working machine according to any one of 5.

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