Work equipment

Abstract

To provide a work machine that is configured so that a motor can be appropriately controlled when the machine falls.SOLUTION: A work machine 1 has a falling protection function of decelerating a motor 6 in response to impact caused when the machine falls and touches the ground. A microcomputer 98 executes deceleration control by which impact caused by the falling of the work machine 1 is sensed on the basis of a detected value by an acceleration sensor 94 to decelerate the motor 6. The deceleration control enables the motor 6 to be decelerated more quickly than by natural deceleration. It is configured that first sensibility which is a degree of influence of acceleration in a first direction on the deceleration control is higher than second sensibility which is a degree of influence of acceleration in a second direction on the deceleration control.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a work machine. [Background technology]

[0002] The following Patent Document 1 discloses a disc grinder as a work machine. Some work machines are equipped with a so-called on-lock function that keeps the motor in a driven state. However, if the motor continues to rotate even after being dropped from the worker's hand, there is a risk of damaging the workpiece. Therefore, a function that detects the impact of the drop using the detection value of an acceleration sensor and decelerates the motor can be considered. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-143492 Summary of the Invention [Problem to be solved by the invention]

[0004] Even when a work machine falls from the same height to the ground, the detected value of the acceleration sensor will differ depending on various factors, such as the material of the point of impact with the ground, the distance from the point of impact to the acceleration sensor, and the configuration of the path along which the impact travels from the point of impact to the acceleration sensor.

[0005] For example, the impact when the gripping part, which is soft for ease of holding, and the metal case that houses the transmission mechanism (gears, etc.) come into contact with the ground can be very different, and the acceleration sensor's detected value can be very different. Also, if the distance from the collision point to the acceleration sensor is large, the amount of impact attenuation along the path from the collision point to the acceleration sensor can be large, which can result in a smaller acceleration sensor detected value.

[0006] Here, if the threshold value for determining whether or not a fall has occurred is set small based on the case where the detected value of the acceleration sensor becomes small, there is a high risk of erroneously determining that a fall has occurred when no fall has occurred.

[0007] Therefore, for example, in a configuration in which the detected value of the acceleration sensor is directly compared with a single threshold value to determine whether or not a fall has occurred, the motor may not be able to be decelerated appropriately.

[0008] Although the above description is based on the case where the motor continues to rotate when the machine is dropped, the problem is not limited to drops. For example, it is also possible that the machine may be thrown horizontally due to an operator's fall, and if the motor continues to rotate even in such a case, there is a risk of damaging the workpiece.

[0009] An object of the present invention is to provide a work machine that can suitably control a motor. [Means for solving the problem]

[0010] One aspect of the present invention is a work machine. Housing and a motor accommodated in the housing; Supported by the housing , th an acceleration sensor that detects acceleration in one direction and acceleration in a second direction; a controller that executes deceleration control to decelerate the motor based on the acceleration in the first direction and the acceleration in the second direction, a first distance from the acceleration sensor to an edge of a surface of the work machine in the first direction is greater than a second distance from the acceleration sensor to an edge of a surface of the work machine in the second direction; The controller the deceleration control a condition for executing the step (a) includes a calculated value exceeding a predetermined threshold, and the calculated value is the detected acceleration in the first direction. a first sensitivity, which is the degree of influence of acceleration in the first direction on the and the detected acceleration in the second direction. a second sensitivity, which is the degree of influence of acceleration in the second direction on the and a second value reflecting The first sensitivity is the second sensitivityIt is configured to be higher than

[0011] Another aspect of the present invention is a work machine. Housing and a motor accommodated in the housing; an acceleration sensor supported by the housing and configured to output acceleration in a first direction and acceleration in a second direction; a controller for controlling the motor, A work machine in which, when a drop collision occurs, the detected acceleration value by the acceleration sensor is larger when an impact in a direction opposite to the first direction is applied to the first direction side end of the housing than when an impact in a direction opposite to the second direction is applied to the second direction side end of the housing, even if the magnitudes of the impacts in the former and latter are the same; The controller Acceleration in the first direction and the first coefficient product of , and Acceleration in the second direction and second coefficient product of , by a function containing Calculation Out was When the value exceeds a threshold, deceleration control is performed to decelerate the motor. It is configured as follows: The first coefficient but The second coefficient is set to a value smaller than .

[0012] Another aspect of the present invention is a work machine. Housing and a motor accommodated in the housing; an acceleration sensor supported by the housing; The motor is driven in response to the output of the acceleration sensor. control a control unit for With death, In the event of a drop collision, a first case is defined as a case in which an impact is applied to a first direction side end of the housing in a direction opposite to the first direction, and a second case is defined as a case in which an impact is applied to a second direction side end of the housing in a direction opposite to the second direction. Even if the magnitude of the impact is the same in the first case and the second case, the acceleration detected by the acceleration sensor in the first case is larger than that in the second case. A work machine, The control unit decelerates the motor when the impact exceeds a first magnitude in the first case, and decelerates the motor when the impact exceeds a second magnitude that is smaller than the first magnitude in the second case. .

[0013] The present invention may be expressed as an "electric working machine," "electric tool," "electrical equipment," etc., and such expressions are also valid as aspects of the present invention. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a work machine that is capable of suitably controlling a motor. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a left side view of a work machine 1 according to an embodiment of the present invention. [Figure 2] FIG. [Figure 3] FIG. 3 is a left side view of the work machine 1, showing distances L1 to L4. [Figure 4] FIG. 2 is a plan view of the work machine 1, showing distances L1, L2, L5, and L6. [Figure 5] FIG. 2 is a circuit block diagram of the work machine 1. [Figure 6] 4 is a flowchart showing a first example of fall protection control for the work machine 1. [Figure 7] 6 is a flowchart showing a second example of fall protection control for the work machine 1. [Figure 8] FIG. 2 is a plan view of the work machine 1, showing distances L7, L8, and L9. DETAILED DESCRIPTION OF THE INVENTION

[0016] This embodiment relates to a work machine 1. The work machine 1 is a grinder (disc grinder). Figures 1 and 4 define the mutually orthogonal front-to-rear, up-down, and left-to-right directions (X, Y, and Z axis directions) of the work machine 1. The front-to-rear direction is a direction parallel to the motor shaft 6a (or the extension direction of the gripping portion 3b). The up-down direction is a direction parallel to the central axis of the spindle 20. The left-to-right direction is based on the operator facing forward. In addition, the +Z direction is defined as the forward direction, the -Z direction as the backward direction, the +X direction as the downward direction, the -X direction as the upward direction, the +Y direction as the leftward direction, and the -Y direction as the rightward direction.

[0017] As shown in Figures 1 and 2, the work machine 1 is equipped with a grinding wheel 2 as a working part (rotary tool). The work machine 1 can perform predetermined tasks such as grinding and cutting using the grinding wheel 2, which is driven to rotate by a motor 6, which will be described later. The work machine 1 has a housing 3 and a gear case 4. Note that the housing in the present invention refers to the entire work machine 1. Therefore, the housing in the present invention includes the housing 3 and the gear case 4, as well as the grinding wheel 2 and the battery 7, which will be described later. Because the housing in the present invention refers to the entire work machine 1, it may also be simply referred to as the work machine.

[0018] The housing 3 is, for example, a resin molded body, and has a tubular shape, for example, a cylindrical shape, with a central axis substantially parallel to the front-rear direction. The housing 3 has a motor accommodating portion 3a, a grip portion 3b, and an expanded diameter portion 3c. The motor accommodating portion 3a accommodates the motor 6. The grip portion 3b is connected to the rear of the motor accommodating portion 3a. The grip portion 3b has a smaller diameter than the motor accommodating portion 3a. The grip portion 3b is configured so that its grip axis extends along the front-rear direction. In other words, the grip portion 3b extends in the front-rear direction. An elastomer (soft resin) is provided on the outer surface of the grip portion 3b. The elastomer of the grip portion 3b has a high friction coefficient, making it less likely for the operator's hand to slip. The soft elastomer of the grip portion 3b also improves gripping ease. The expanded diameter portion 3c is connected to the rear of the grip portion 3b. The outer surface of the expanded diameter portion 3c is provided with an elastomer (soft resin). The expanded diameter portion 3c has a shape that protrudes in the radial direction. During operation or transportation, the expanded diameter portion 3c may come into contact with the workpiece, wall, workbench, etc., potentially damaging or deforming these objects. However, providing an elastomer in the expanded diameter portion 3c prevents this. The elastomer in the expanded diameter portion 3c also prevents damage and deformation of the expanded diameter portion 3c. The expanded diameter portion 3c also has a battery holder 3d. That is, the rear end of the housing 3 is provided with the battery holder 3d, to which a battery 7, which serves as the power source for the work machine 1, is detachably attached. Therefore, the battery 7 is located at the rear end of the work machine 1.

[0019] The gear case 4 is made of metal such as aluminum alloy, and is attached and fixed to the front end of the housing 3 by screws or the like. That is, the gear case 4 is disposed at the front end portion of the work machine 1. The work machine 1 has a packing gland 11 as a cover member that closes the lower opening of the gear case 4.

[0020] The work machine 1 has a motor 6 in the housing 3 (motor accommodating section 3a). The motor 6 is, for example, a brushless motor of an inner rotor type with a 4-pole, 6-slot configuration. The front end of the motor shaft 6a is located inside the gear case 4, and a first bevel gear 21 is provided at the front end.

[0021] A fan 8 for cooling the motor 6 and the like is provided on the motor shaft 6a. The fan 8 is located in the housing 3 in front of the main body of the motor 6 (the part of the motor 6 excluding the motor shaft 6a).

[0022] The work machine 1 has a switch 5 behind the motor 6 in the housing 3 (inside the grip portion 3b). When the switch 5 is in the on state, it instructs the microcomputer 98 in FIG. 5 to drive the motor 6. When the switch 5 is in the off state, it instructs the microcomputer 98 to stop the motor 6.

[0023] The work machine 1 has an operation unit 10 at the front of the left side surface of the housing 3 (motor accommodating section 3a) that allows the user to turn on and off the switch 5, i.e., to instruct the microcomputer 98 to drive or stop the motor 6. The work machine 1 has a slide bar 17 inside the housing 3 that moves in the front-to-rear direction in conjunction with the front-to-rear operation of the operation unit 10. Note that due to the position of the cross section, only the rear end portion of the slide bar 17 that extends in the front-to-rear direction is shown in the figure.

[0024] When the user performs a driving operation to move the operation unit 10 forward, the slide bar 17 moves forward in conjunction with the operation, and the slide bar 17 presses the button 5a of the switch 5, turning the switch 5 on (entering the on state).

[0025] When the user performs a stop operation to move the operation unit 10 backward, the slide bar 17 moves backward in conjunction with this, the slide bar 17 no longer presses the button 5a, and the switch 5 is turned off (enters the OFF state).

[0026] As shown in Fig. 1, the housing 3 has a locking protrusion 18 at the front of the left side surface. By hooking the operating unit 10 onto the locking protrusion 18, the operating unit 10 is locked in a position where it has moved forward, and the switch 5 can be maintained in an on state even if the operating unit 10 is released, and the motor 6 can be maintained in a driven state.

[0027] As shown in FIG. 2, the work machine 1 has a control board 9 at the rear end within the housing 3. The control board 9 is supported by the housing 3 and is equipped with elements necessary for drive control of the motor 6, such as the inverter circuit 82 and microcomputer 98 shown in FIG. 5. The control board 9 also has an acceleration sensor 94 that detects acceleration when the work machine 1 falls and hits the ground. The acceleration sensor 94 is a triaxial acceleration sensor that detects acceleration in the X, Y, and Z directions, which are three orthogonal axes. The acceleration sensor 94 is supported by the housing 3. The detection axes of the acceleration sensor 94, the X, Y, and Z axes, are aligned along the up-down, left-right, and front-to-back directions of the work machine 1, respectively.

[0028] The work machine 1 has a speed setting dial 19 on the upper rear surface of the housing 3. The user can change the set rotational speed of the motor 6 by operating the speed setting dial 19.

[0029] The gear case 4 and the packing gland 11 rotatably support the spindle 20. The gear case 4 is provided with a needle bearing 12 that rotatably supports the upper end of the spindle 20. The packing gland 11 holds a ball bearing 13 that rotatably supports the middle part of the spindle 20.

[0030] The central axis of the spindle 20 is perpendicular to the motor shaft 6a. One end of the spindle 20 penetrates the packing gland 11 and protrudes to the outside. A second bevel gear 22 is provided (attached) to the upper part of the spindle 20 located inside the gear case 4. The second bevel gear 22 meshes with the first bevel gear 21.

[0031] The rotation of the motor 6 is converted in its direction by 90 degrees by the first bevel gear 21 and the second bevel gear 22, and the rotation speed is reduced before being transmitted to the spindle 20. In other words, the spindle 20 is rotationally driven by the motor 6.

[0032] The grinding wheel 2 is fixed to the spindle 20 and rotates integrally with the spindle 20. The wheel guard 14 is attached to the packing gland 11 and covers approximately half of the grinding wheel 2, preventing the scattering of cutting powder, sparks, etc. that are generated during grinding work.

[0033] When the user operates the operating unit 10, power is supplied from the battery 7 to the motor 6, causing the motor shaft 6a to rotate, which in turn causes the spindle 20 to rotate via the first bevel gear 21 and the second bevel gear 22, and the grinding wheel 2 fixed to the spindle 20 to rotate.

[0034] 3 and 4 show distances L1 to L6 in the work machine 1. FIG.

[0035] Distance L1 is the distance from the acceleration sensor 94 to the surface edge of the work machine 1 in the forward direction (+Z direction). In this embodiment, the surface edge of the work machine 1 in the forward direction (+Z direction) is the front end portion of the grinding wheel 2. Distance L2 is the distance from the acceleration sensor 94 to the surface edge of the work machine 1 in the rear direction (-Z direction). In this embodiment, the surface edge of the work machine 1 in the rear direction (-Z direction) is the rear end portion of the battery 7.

[0036] Distance L3 is the distance from the acceleration sensor 94 to the surface edge of the work machine 1 in the upward direction (-X direction). In this embodiment, the surface edge of the work machine 1 in the upward direction (-X direction) is the upper end portion of the battery 7. Distance L4 is the distance from the acceleration sensor 94 to the surface edge of the work machine 1 in the downward direction (+X direction). In this embodiment, the surface edge of the work machine 1 in the downward direction (+X direction) is the lower end portion of the wheel guard 14.

[0037] Distance L5 is the distance in the right direction (-Y direction) from the acceleration sensor 94 to the surface edge of the work implement 1. Distance L6 is the distance in the left direction (+Y direction) from the acceleration sensor 94 to the surface edge of the work implement 1.

[0038] The relationship between the distances L1 to L6 is as follows: L1>L2>L4>L3≒L5=L6 Here, a first distance and a second distance smaller than the first distance are defined.

[0039] If the forward direction (+Z direction) is defined as the first direction, i.e., if distance L1 is defined as the first distance, then the five directions other than the forward direction (+Z direction) can each be the second direction. That is, distances L2 to L6 can each be the second distance.

[0040] If the backward direction (-Z direction) is the first direction, that is, if the distance L2 is the first distance, then the up, down, left, and right directions can each be the second direction. That is, the distances L3 to L6 can be the second distances.

[0041] If the downward direction (+X direction) is the first direction, i.e., if distance L4 is the first distance, then the upward, left, and right directions can be second directions, i.e., distances L3, L5, and L6 can be second distances.

[0042] 5 is a circuit block diagram of the work machine 1. The work machine 1 includes a control circuit unit 80, an inverter circuit 82, and a magnetic sensor 84. The control circuit unit 80 includes a control signal output circuit 83, a rotor position detection circuit 85, a temperature detection circuit 86, a step-down circuit 87, a control system power supply circuit 88, a battery voltage detection circuit 89, an over-discharge detection circuit 90, a current detection circuit 91, a communication circuit 92, a battery temperature detection circuit 93, an acceleration sensor 94, a switch detection circuit 95, a set rotation speed detection circuit 96, and a microcomputer 98 (microcontroller) as a control unit.

[0043] The inverter circuit 82 includes semiconductor switching elements Q1 to Q6 connected in a three-phase bridge. The inverter circuit 82 converts the DC power output from the battery 7 into AC power for driving the motor 6 and supplies it to the motor 6. The control signal output circuit 83 applies a drive signal, for example a PWM (Pulse Width Modulation) signal, to each gate of the switching elements Q1 to Q6 under the control of the microcomputer 98.

[0044] The magnetic sensors 84 are, for example, Hall ICs, and are provided at 60° intervals in the rotational direction of the motor 6. The magnetic sensors 84 detect the magnetic field generated by the rotor of the motor 6 and send the signal to a rotor position detection circuit 85. The rotor position detection circuit 85 detects the rotor position of the motor 6 based on a signal from the magnetic sensors 84 and sends the signal to a microcomputer 98. The magnetic sensors 84 and the rotor position detection circuit 85 constitute a rotation detection unit. The temperature detection circuit 86 detects the temperatures of the switching elements Q1 to Q6 and sends the signal to the microcomputer 98.

[0045] The step-down circuit 87 steps down the output voltage of the battery 7 and supplies it to a control system power supply circuit 88. The control system power supply circuit 88 converts the output voltage of the step-down circuit 87 into a power supply voltage for the microcomputer 98, etc. and supplies it to the microcomputer 98, etc. The battery voltage detection circuit 89 detects the output voltage of the battery 7 and sends it to the microcomputer 98.

[0046] The over-discharge detection circuit 90 detects an over-discharge notification signal from the battery 7 and transmits it to the microcomputer 98. The current detection circuit 91 detects the motor current from the voltage of a resistor R provided in the path of the current (motor current) flowing through the motor 6 and transmits it to the microcomputer 98. The resistor R and the current detection circuit 91 form a current detection unit. The communication circuit 92 is a circuit for communication between the battery 7 and the microcomputer 98. The battery temperature detection circuit 93 detects a temperature notification signal from the battery 7 and transmits it to the microcomputer 98.

[0047] An acceleration sensor 94 detects acceleration applied to the work machine 1 and sends the detected result to the microcomputer 98. A switch detection circuit 95 detects the operation of the operation unit 10, i.e., the on / off of the switch 5, and sends the detected result to the microcomputer 98. A set rotation speed detection circuit 96 detects the set rotation speed set by the speed setting dial 19 and sends the detected result to the microcomputer 98.

[0048] The microcomputer 98 is configured to control the inverter circuit 82 via the control signal output circuit 83, for example, by PWM control, in response to the operation of the operation unit 10, i.e., the on / off of the switch 5, and the rotation speed set by the speed setting dial 19, thereby controlling the drive of the motor 6. The microcomputer 98 can change the effective value of the voltage applied to the motor 6 (hereinafter referred to as "motor applied voltage") by changing the duty of the PWM control (hereinafter referred to as "duty"). The microcomputer 98 can change the output of the motor 6 by controlling the effective value of the motor applied voltage.

[0049] The work machine 1 is characterized by a fall protection function that decelerates the motor 6 in response to the impact when it falls and hits the ground. Deceleration includes stopping the work machine.

[0050] The microcomputer 98 is a controller that detects an impact applied to the work machine 1 due to a fall or the like based on the detection value of the acceleration sensor 94 and executes deceleration control to decelerate the motor 6. The deceleration control preferably decelerates the motor 6 faster than natural deceleration. In this embodiment, the deceleration control is brake control. The brake control in this embodiment is a well-known short-circuit brake that is performed by controlling the inverter circuit 82. Note that other means for decelerating the motor 6 may also be used.

[0051] In this embodiment, the first sensitivity, which is the degree of influence that acceleration in a first direction has on the deceleration control, is configured to be higher than the second sensitivity, which is the degree of influence that acceleration in a second direction has on the deceleration control. That is, the conditions for executing the deceleration control (the smallest impact that can cause the deceleration control) are configured to be different between an impact in the first direction and an impact in a second direction different from the first direction. A specific example is shown below.

[0052] First, we will explain the structural features of this embodiment that are necessary for considering deceleration control. In the work machine 1 (disc grinder) of this embodiment, the acceleration sensor 94 is located inside the expanded diameter portion 3c, i.e., in a rear portion (relative to the center position in the front-to-rear direction) of the work machine 1. Therefore, the acceleration sensor 94 is located far from the front end of the work machine 1 and close to the rear end. Although the magnitude of the impact detected by the acceleration sensor 94 is affected by various factors, in this embodiment, the distance from the point of impact to the acceleration sensor 94 significantly affects the detection result (the acceleration value detected at the time of impact). In this embodiment, even when dropped from the same height, for example, the detected impact (acceleration) tends to be smaller as the distance from the acceleration sensor 94 to the impact point increases. Specifically, when the work machine is dropped with the gear case 4 facing downwards and when the battery 7 is facing downwards, even when the drop collision occurs from the same height (the same magnitude of impact is occurring in the direction toward the acceleration sensor 94), the detection result of the acceleration sensor 94 tends to be smaller in the former case. Furthermore, because elastomer is provided on the outer surfaces of the gripping portion 3b and the enlarged diameter portion 3c, impacts applied to these portions are also attenuated. The control (first and second examples) of the present invention, which was designed based on various factors including these features, will be explained using flowcharts. Details will be described later, but whether or not to execute deceleration control is determined by comparing a calculated value using acceleration in three directions (directions of three axes) detected by the acceleration sensor 94 with a threshold value. The present invention (first and second examples) solves the problem by correcting at least one of the calculated value and the threshold value according to the direction of the impact (the location where the impact is applied).

[0053] 6 is a flowchart showing a first example of fall protection control for the work machine 1. This flowchart starts with the switch 5 turned on and the motor 6 driven. The microcomputer 98 acquires the detected values ​​of the acceleration sensor 94, i.e., the X-direction acceleration ax, the Y-direction acceleration ay, and the Z-direction acceleration az (S1).

[0054] If ax≦0 (yes in S3), the microcomputer 98 substitutes kx×ax for ax (S5), where kx is a constant (coefficient) that is preset (stored) in correspondence with the acceleration in the −X direction.

[0055] If ax≦0 is not satisfied (no in S3), the microcomputer 98 assigns kx′×ax to ax (S7), where kx′ is a constant (coefficient) that is preset (stored) in correspondence with the acceleration in the +X direction.

[0056] If ay≦0 (yes in S9), the microcomputer 98 substitutes ky×ay for ay (S11), where ky is a constant (coefficient) that is set (stored) in advance in correspondence with the acceleration in the −Y direction.

[0057] If ay≦0 is not satisfied (no in S9), the microcomputer 98 assigns ky′×ay to ay (S13), where ky′ is a constant (coefficient) previously set (stored) corresponding to the acceleration in the +Y direction.

[0058] If az≦0 (yes in S15), the microcomputer 98 substitutes kz×az for az (S17), where kz is a constant (coefficient) that is set (stored) in advance in correspondence with the acceleration in the −Z direction.

[0059] If az≦0 is not satisfied (no in S15), the microcomputer 98 assigns kz′×az to az (S19), where kz′ is a constant (coefficient) that is preset (stored) in accordance with the acceleration in the +Z direction.

[0060] The microcomputer 98 calculates the scalar value a of the resultant acceleration of the three axes, i.e., the square root of the sum of the squares of ax, ay, and az (S21). The scalar value a corresponds to the resultant value, and the square root of the sum of the squares corresponds to a function. If the scalar value a of the resultant acceleration of the three axes is equal to or less than the fall protection function activation threshold alim (no in S23), the microcomputer 98 returns to S1. If the scalar value a of the resultant acceleration of the three axes is greater than the fall protection function activation threshold alim (yes in S23), the microcomputer 98 determines that the work machine 1 has fallen and stops the motor 6 (S25). Here, instead of stopping the motor, deceleration without stopping the motor may be performed.

[0061] The magnitude relationship between each constant (each coefficient) is as follows: kz'>kz>kx'>kx≒ky=ky' This is based on the above-mentioned relationship of distance magnitude L1>L2>L4>L3≒L5=L6. That is, when the distance from the acceleration sensor 94 is farther, each constant (coefficient) is made larger compared to when the distance is closer. As will be described in detail later, the larger each constant is, the more easily deceleration control can be performed even if the acceleration detected by the acceleration sensor 94 is small.

[0062] Setting kz' > kz ​​means that the +Z direction sensitivity, which is the degree of influence that acceleration in the +Z direction has on deceleration control, is made higher than the -Z direction sensitivity, which is the degree of influence that acceleration in the -Z direction has on deceleration control. Specifically, the sensitivity when the work machine 1 is dropped with the gear case 4 facing downwards and a collision occurs is made higher than the sensitivity when the work machine 1 is dropped with the battery 7 facing downwards. In other words, when the work machine 1 is moved in the +Z direction and a collision occurs, the sensitivity of the deceleration control is made higher compared to when the work machine 1 is moved in the -Z direction and a collision occurs. Therefore, when the work machine 1 is dropped in the +Z direction and a collision occurs, deceleration control is executed even if the acceleration detected by the acceleration sensor 94 is smaller (even if the impact transmitted to the acceleration sensor 94 is weaker) compared to when the work machine 1 is dropped in the -Z direction.

[0063] Setting kz>kx' means that the -Z direction sensitivity is made higher than the +X direction sensitivity, which is the degree of effect that acceleration in the +X direction has on deceleration control. Specifically, the sensitivity when the work machine 1 is dropped with the gear case 4 facing downwards and a collision occurs is made higher than the sensitivity when the work machine 1 is dropped with the upper part (the part opposite the protruding direction of the spindle 20) facing downwards.

[0064] Setting kx' > kx means that the +X direction sensitivity is made higher than the -X direction sensitivity, which is the degree of effect that acceleration in the -X direction has on deceleration control. Specifically, the sensitivity when the work machine 1 is dropped with its upper part facing downwards and a collision occurs is made higher than the sensitivity when the work machine 1 is dropped with its lower part (the surface opposite to the protruding direction of the spindle 20) facing downwards. This is the result of taking into consideration that the acceleration detected by the elastomer provided in the enlarged diameter portion 3c becomes smaller.

[0065] Setting kx ≒ ky = ky' means making the -X direction sensitivity equal to the -Y direction sensitivity, which is the degree of influence that acceleration in the -Y direction has on deceleration control, and the +Y direction sensitivity, which is the degree of influence that acceleration in the +Y direction has on deceleration control. As described above, the first example corrects the detected acceleration by multiplying it by a coefficient, and executes appropriate deceleration control depending on the direction of the impact (drop).

[0066] 7 is a flowchart showing a second example of fall protection control for the work machine 1. This flowchart starts from a state in which the switch 5 is on and the motor 6 is driven. The microcomputer 98 acquires the detection values ​​of the acceleration sensor 94, i.e., the X-direction acceleration ax, the Y-direction acceleration ay, and the Z-direction acceleration az (S31).

[0067] The microcomputer 98 stores in advance the fall protection function activation thresholds alimx, alimx', alimy, alimy', alimz, and alimz' corresponding to the accelerations in the +X, -X, +Y, -Y, +Z, and -Z directions.

[0068] The microcomputer 98 returns to S31 if alimx'≦ax≦alimx (yes in S33), if alimy'≦ay≦alimy (yes in S35), or if alimz'≦az≦alimz (yes in S37).

[0069] When the microcomputer 98 determines that the operating machine 1 has fallen because ax is not within alimx’ ≤ ax ≤ alimx (no in S33), ay is not within alimy’ ≤ ay ≤ alimy (no in S35), or az is not within alimz’ ≤ az ≤ alimz (no in S37), it stops the motor 6 (S39). Here, instead of stopping, deceleration (control to reduce the rotational speed) without stopping may be used.

[0070] The magnitude relationship of the absolute values of the respective fall protection function activation thresholds is alimz < alimz’ < alimx < alimx’ ≒ alimy’ = alimy is set as follows.

[0071] Setting alimz < alimz’ means making the +Z direction sensitivity higher than the -Z direction sensitivity. Even in this case, similar to the first example, when falling in the +Z direction, even if the acceleration detected by the acceleration sensor 94 is small (even if the impact transmitted to the acceleration sensor 94 is weak) compared to when falling in the -Z direction, deceleration control is executed.

[0072] Setting alimz’ < alimx means making the -Z direction sensitivity higher than the +X direction sensitivity.

[0073] Setting alimx < alimx’ means making the +X direction sensitivity higher than the -X direction sensitivity.

[0074] Setting alimx’ ≒ alimy’ = alimy means making the -X direction sensitivity equivalent to the -Y direction sensitivity and the +Y direction sensitivity. As described above, in the second example, the thresholds used for deceleration control are made different according to the direction of the impact (fall).

[0075] The example in FIG. 6 (correction of acceleration detection values) can preferably handle the case where the operating machine 1 falls in a halfway posture, for example, a posture where the Z direction is deviated by 45° from the vertical direction, compared to the example in FIG. 7 (adjustment of thresholds).

[0076] The example of FIG. 7 (adjustment of threshold value) simplifies the control compared to the example of FIG. 6 (correction of detected acceleration value).

[0077] In both the example of Figure 6 (correction of acceleration detection value) and the example of Figure 7 (adjustment of threshold value), the detection value of the acceleration sensor 94 changes due to various factors, so it is desirable to create a program taking into account various expected situations.

[0078] An example of fall protection control different from the examples of FIGS. 6 and 7 will be described below.

[0079] The microcomputer 98 derives a three-axis resultant acceleration vector and its magnitude from the detected values ​​of the acceleration sensor 94, that is, the X-direction acceleration ax, the Y-direction acceleration ay, and the Z-direction acceleration az.

[0080] The microcomputer 98 stores in advance constants (coefficients) corresponding to the direction of the three-axis resultant acceleration vector. From the direction of the three-axis resultant acceleration vector, various factors that affect the detection value of the acceleration sensor 94, such as the material of the collision point, the distance from the collision point to the acceleration sensor 94, and the configuration of the path along which the impact travels from the collision point to the acceleration sensor 94, can be estimated. Constants (coefficients) that comprehensively take these factors into consideration are found by simulation, experiment, etc., and are stored in the microcomputer 98.

[0081] The microcomputer 98 multiplies the magnitude of the three-axis resultant acceleration vector by the constant (coefficient) specified from the direction of the three-axis resultant acceleration vector to obtain an adjusted resultant acceleration. If the adjusted resultant acceleration exceeds the fall protection function activation threshold, the microcomputer 98 determines that the work machine 1 has fallen and stops the motor 6. Here, instead of stopping the motor 6, it is also possible to decelerate the motor 6 without stopping it.

[0082] In this example, by preparing a large number of constants (coefficients) corresponding to the directions of the three-axis resultant acceleration vector, it is possible to suitably handle various falling postures.

[0083] Furthermore, in the above-described embodiment, L1 to L6 are described as the distances from the acceleration sensor 94 in the front-back, left-right, up-down directions, and the corresponding changes in coefficients or thresholds. However, this is merely to briefly explain an example of the control of the present invention and the procedure for establishing said control, and it is of course possible to realize the control of the present invention using a different method.

[0084] For example, although L1 to L6 are distances in the front-rear, left-right, and up-down directions, the sensitivity of the deceleration control (the coefficient by which the detected acceleration is multiplied, or the threshold value) may be changed simply depending on the distance from the acceleration sensor 94 to the outer surface of the work machine 1, regardless of the direction. FIG. 8 shows distance L7 from the acceleration sensor 94 to the outer surface portion of the work machine 1 farthest from the acceleration sensor 94 (the front end of the grinding wheel 2), distance L8 from the acceleration sensor 94 to the outer surface portion of the work machine 1 closest to the acceleration sensor 94 (the upper rear end of the gripper 3b), and distance L9 to the outer surface portion between them (the lower end of the battery 7). In this case, the relationship between the distances is L7 > L9 > L8, so the sensitivity of the deceleration control should be increased in the following order for a drop with the front end of the grinding wheel 2 facing downward, a drop with the lower end of the battery 7 facing downward, and a drop with the upper rear end of the gripper 3b facing downward. Note that when performing deceleration control, it is important that the direction of the impact is the direction of the acceleration sensor 94. Naturally, when the grinding wheel 2 is dropped with its front end facing downwards, an upward impact is applied to the grinding wheel 2, and since the acceleration sensor 94 is located above the grinding wheel 2, an impact is applied to the grinding wheel 2 (work machine 1) in the direction toward the acceleration sensor 94, and the acceleration sensor 94 can accurately detect the impact when dropped.

[0085] Depending on the configuration of the work machine, the impact of a drop collision may be detected weakly (or strongly) only in a certain posture. Even in such cases, the sensitivity of the deceleration control for that certain posture can be adjusted. That is, when an impact is applied in a direction toward the acceleration sensor to the surface location farthest from the acceleration sensor in each of the front-rear, left-right, up-down, and down directions of the work machine in a certain posture, the magnitude of the acceleration sensor output required to execute deceleration control can be configured to be different in at least one of the front-rear, left-right, up-down, and down directions. In other words, when executing deceleration control, the sensitivity can be increased (or decreased) in at least one situation in which the acceleration is detected as relatively weak (or strong) even when the impact force applied to the outer surface of the work machine 1 (housing) is the same.

[0086] According to this embodiment, the detection value of the acceleration sensor 94 is corrected and then compared with the fall protection function activation threshold, or the detection value of the acceleration sensor 94 is compared with the fall protection function activation threshold adjusted for each direction, to determine whether deceleration control of the motor 6 is necessary. This allows the motor 6 to be appropriately decelerated when the work machine 1 is falling. In other words, a work machine 1 capable of appropriately controlling the motor 6 when falling can be realized. Conventionally, when deceleration control is performed to stop the motor 6 in the event of a fall collision, for example, depending on the posture during the fall, problems may arise, such as the motor 6 being overly sensitive to impact and easily stopping, or being insensitive to impact and not stopping. Specifically, for example, in the first posture, the motor 6 may be stopped by a fall from a height of 1.0 m or more, but in the second posture, the motor 6 may stop by a fall from a height of 0.3 m (a weak impact), and in the third posture, the motor 6 may not stop even when dropped from a height of 1.5 m. In this embodiment, the sensitivity when decelerating the motor 6 is changed depending on the direction of the impact, thereby solving these problems. For example, according to this embodiment, it is possible to configure the motor 6 to be decelerated when the work machine 1 is dropped from a height of 1.0 m in any of the first, second, and third positions (three positions) described above. Therefore, it is possible to execute appropriate deceleration control in consideration of the environment in which the work machine 1 is used.

[0087] Although the present invention has been described above using the embodiments as examples, the present invention is not limited to the embodiments. Various modifications can be made to the details specifically described in the embodiments within the scope of the claims.

[0088] The acceleration sensor 94 is not limited to a triaxial acceleration sensor and may be a biaxial acceleration sensor. Furthermore, some work machines are configured to allow various accessories to be attached. In such cases, not only the weight of the work machine itself but also the material of the impact point when dropped and the distance from the acceleration sensor 94 to the ground (impact point) may change. Therefore, for example, the attachment status of the accessories may be detected using a sensor or a mechanical switch, and the sensitivity (coefficient) may be changed depending on the attachment status of the accessories. Specifically, for example, the attached battery may be identified and the sensitivity may be adjusted according to its weight (a lighter battery would reduce the impact, so the sensitivity would be increased, or a heavier battery would reduce the sensitivity). Although this embodiment is a grinder, grinders may be configured to allow various types of tool bits to be attached and detached. In such cases, the type of tool bit (softness, weight, etc.) may be detected and identified, and the sensitivity (coefficient) may be changed depending on the results. Furthermore, the working machine of the present invention is not limited to the grinder exemplified in the embodiment, but can be suitably applied to other types of working machines, particularly various working machines equipped with a so-called on-lock function that keeps the switch in the on state (motor in the driven state). [Explanation of symbols]

[0089] 1...Work machine, 2...Grinding wheel (rotary tool), 3...Housing, 4...Gear case, 5...Switch, 5a...Button, 6...Motor (brushless motor), 6a...Motor shaft, 7...Battery (battery pack), 8...Fan, 9...Control board, 10...Operation unit, 11...Packing gland, 12...Needle bearing, 13...Ball bearing, 14...Wheel guard, 17...Slide bar, 18...Latching protrusion, 19...Speed ​​setting dial, 20...Spindle, 21...First bevel gear, 22...second bevel gear, 80...control circuit section, 82...inverter circuit, 83...control signal output circuit, 84...magnetic sensor, 85...rotor position detection circuit, 86...temperature detection circuit, 87...step-down circuit, 88...control system power supply circuit, 89...battery voltage detection circuit, 90...over-discharge detection circuit, 91...current detection circuit, 92...communication circuit, 93...battery temperature detection circuit, 94...acceleration detection circuit, 95...switch detection circuit, 96...set rotation speed detection circuit, 98...microcontroller.

Claims

1. Housing and a motor accommodated in the housing; an acceleration sensor supported by the housing and configured to detect acceleration in a first direction and acceleration in a second direction; a controller that executes deceleration control to decelerate the motor based on the acceleration in the first direction and the acceleration in the second direction, a first distance from the acceleration sensor to an edge of a surface of the work machine in the first direction is greater than a second distance from the acceleration sensor to an edge of a surface of the work machine in the second direction; the controller determines, as a condition for executing the deceleration control, that the calculated value exceeds a predetermined threshold, and the calculated value is calculated using both a first value reflecting a first sensitivity which is a degree of influence of acceleration in the first direction on the detected acceleration in the first direction, and a second value reflecting a second sensitivity which is a degree of influence of acceleration in the second direction on the detected acceleration in the second direction; The work machine is configured so that the first sensitivity is higher than the second sensitivity.

2. Housing and a motor accommodated in the housing; an acceleration sensor supported by the housing and configured to output an acceleration in a first direction and an acceleration in a second direction; a controller for controlling the motor, A work machine in which, when a drop collision occurs, the detected acceleration value by the acceleration sensor is larger when an impact in a direction opposite to the first direction is applied to the first direction side end of the housing than when an impact in a direction opposite to the second direction is applied to the second direction side end of the housing, even if the magnitudes of the impacts in the former and latter are the same; the controller is configured to execute deceleration control to decelerate the motor when a value calculated by a function including a product of the acceleration in the first direction and a first coefficient and a product of the acceleration in the second direction and a second coefficient exceeds a threshold; A work machine, wherein the first coefficient is set to a value smaller than the second coefficient.

3. 3. The work machine according to claim 2, wherein a first distance in the first direction from the acceleration sensor to the first-direction side end of the housing is shorter than a second distance in the second direction from the acceleration sensor to the second-direction side end of the housing.

4. The work machine according to claim 1 , wherein the first direction and the second direction are opposite directions.

5. The work machine according to claim 1 , wherein the first direction and the second direction intersect with each other.

6. a gear case provided on the first direction side of the housing; The work machine according to claim 4 , further comprising: a battery pack provided on the second direction side of the housing.

7. a gear case provided on the first direction side of the housing, The work machine according to claim 5 , wherein the second direction is parallel to a radial direction of the motor.

8. The work machine according to claim 2 , wherein a material of the surface end portion of the work machine in the first direction is different from a material of the surface end portion of the work machine in the second direction.

9. The work machine according to claim 8 , wherein a material of the surface end portion of the work machine in the first direction is softer than a material of the surface end portion of the work machine in the second direction.

10. The work machine according to claim 2 , wherein the controller is configured to change at least one of the first coefficient and the second coefficient depending on the type or state of a member attached to the work machine.

11. Housing and a motor accommodated in the housing; an acceleration sensor supported by the housing; a control unit that controls the motor in response to an output of the acceleration sensor; and A work machine in which, in the event of a drop collision, a first case is when an impact is applied to a first direction side end of the housing in a direction opposite to the first direction, and a second case is when an impact is applied to a second direction side end of the housing in a direction opposite to the second direction, and even if the magnitude of the impact is the same in the first case and the second case, the acceleration detection value by the acceleration sensor is larger in the first case than in the second case, The control unit decelerates the motor when the impact exceeds a first magnitude in the first case, and decelerates the motor when the impact exceeds a second magnitude that is smaller than the first magnitude in the second case.

12. the acceleration sensor is located rearward of the center position of the housing in the front-rear direction, 12. The work machine according to claim 11, wherein the control unit is configured so that the magnitude of the output required to decelerate the motor when an impact in a direction toward the acceleration sensor is applied to a surface portion of the housing farthest forward from the acceleration sensor is smaller than the output required to decelerate the motor when an impact in a direction toward the acceleration sensor is applied to a surface portion of the housing farthest rearward from the acceleration sensor.

13. The housing is provided with a grip portion that can be gripped by an operator and extends in the front-rear direction, The work machine according to claim 12, wherein the acceleration sensor is located rearward of the grip portion.

14. The work machine according to claim 13, wherein a metal gear case is provided at a front end portion of the housing.

15. The work machine according to claim 14, wherein a battery is provided at the rear end portion of the housing.

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