JP2018069394A - Work tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a work tool that can execute a shaking prevention function of a main body thereof appropriately even if the kind of a battery pack to be attached to is changed.SOLUTION: A hammer drill 1 as a work tool comprises: a main body 2 having a battery attachment part to which a battery pack 15 is detachably attached; a motor 3 which is activated by power supplied from the battery pack 15; battery kind discriminating means that discriminates the kind of the battery pack 15; an acceleration sensor 23 that detects acceleration of the main body 2; and a control circuit 71 that stops the motor 3 when the detected acceleration is above a first threshold value. The first threshold value is determined depending on the kind of the battery pack 15.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a work tool such as a hammer drill that operates with power supplied from a battery pack that is detachably mounted.

  2. Description of the Related Art Conventionally, work tools that form a hole in a work material such as concrete or apply a striking force by rotating and striking a tip tool by driving a motor are widely known. Among such work tools, there is one that detects that the tool body is swung by a lock of the working unit or the like by an acceleration sensor and prevents the body from being swung by stopping the motor.

JP 2013-094870 A

  In recent years, there is a demand for a cordless tool that operates with power supplied from a battery pack that is detachably mounted so that a battery pack having a greatly different voltage specification can be used in one tool body. For tools that can be equipped with different types of battery packs, if the acceleration applied to the tool body is detected by an acceleration sensor to prevent the tool body from being swung unexpectedly, the tool body is swung by the weight of the battery pack that is installed. Therefore, there is a problem that the acceleration value applied to the main body is different and it is difficult to reliably operate the main body shake prevention function when necessary.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a work tool capable of appropriately performing the shake prevention function of the main body even when the type of the battery pack to be mounted is changed. It is in.

One embodiment of the present invention is a work tool. This work tool is
A main body having a battery mounting portion for detachably mounting the battery pack;
A motor that operates with power supplied from the battery pack;
Acceleration detecting means for detecting the acceleration of the main body;
A controller that stops the motor when the detected acceleration is greater than or equal to a first threshold,
The first threshold value is determined according to a type of the battery pack.

  The type of the battery pack may include at least one of a rated voltage and a rated discharge capacity of the battery pack, a weight of the battery pack, and a number of battery cells built in the battery pack.

  The first threshold value when the weight of the battery pack is large may be smaller than the first threshold value when the weight of the battery pack is small.

Comprising current detection means for detecting the current flowing through the motor;
The control unit stops the motor when the detected current is equal to or greater than a second threshold,
The second threshold value may be determined according to the type of the battery pack.

The type of the battery pack includes information capable of specifying the rated voltage of the battery pack,
The second threshold value when the rated voltage of the battery pack is high may be larger than the second threshold value when the rated voltage of the battery pack is low.

  It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, even if the kind of battery pack to mount changes, the working tool which can perform appropriately the shake prevention function of a main body can be provided.

The left view which shows the external appearance of the hammer drill 1 which concerns on embodiment of this invention. FIG. 3 is a right sectional view showing the internal structure of the hammer drill 1. FIG. 3 is a circuit block diagram showing an electrical configuration of the hammer drill 1. It is a body swing prevention function operation condition table (interruption condition table) of the hammer drill 1, and it is determined whether or not to stop the motor 3 determined for each type (battery type) of the battery pack 15 that can be attached to and detached from the hammer drill 1. The table which shows an example of the acceleration value discrimination | determination condition to perform and the current value discrimination | determination condition. The wave form diagram which shows an example of the time change of an acceleration and an electric current when the main body 2 of the hammer drill 1 is swung by the lock | rock of a working part at the time of starting of the motor 3. FIG. 3 is a control flowchart of the hammer drill 1.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, process, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  FIG. 1 is a left side view showing an appearance of a hammer drill 1 according to an embodiment of the present invention. FIG. 2 is a right side sectional view showing the internal structure of the hammer drill 1. The hammer drill 1 is an example of a work tool (power tool), and has a main body 2 forming an outline. As shown in FIG. 1, a tool mounting portion 10 is provided at one end (front end) of the main body 2 of the hammer drill 1. A tip tool 14 such as a drill blade can be attached to the tool attachment portion 10 according to the work application (see FIG. 2). A handle 11 for the operator to hold is provided at the other end (rear end) opposite to the one end where the tool mounting portion 10 of the main body 2 is provided. A trigger switch 12 is provided as an example of an operation unit that can be manually operated. It should be noted that a side handle (not shown) can be further attached to the main body 2 for two-hand work depending on the work application.

  In the following description, “front” indicated by an arrow in FIG. 1 is defined as a front direction, “rear” is defined as a rear direction, “up” is defined as an upward direction, and “down” is defined as a downward direction. Further, when the hammer drill 1 is viewed from behind, the left is defined as the left direction and the right is defined as the right direction.

  As shown in FIG. 1, a battery mounting portion 21 is provided below the handle 11 of the main body 2. A battery pack 15 that supplies power for driving a motor 3 (described later) is detachably mounted on the battery mounting portion 21. Specifically, the battery pack 15 is attached to and detached from the battery mounting portion 21 in the front-rear direction with respect to the main body 2 as indicated by an arrow A in FIG. In the present embodiment, two types of battery packs 15 whose outputs (rated voltage) are 18V and 36V can be mounted on the battery mounting portion 21 in accordance with the work application. In the present embodiment, battery pack 15 is a battery pack for an electric tool having a plurality of secondary battery cells.

  The operator holds the handle 11 in a state where the battery pack 15 is mounted on the battery mounting portion 21, and the trigger switch 12 in a state where the tip tool 14 mounted on the tool mounting portion 10 contacts the work material. The hammer drill 1 can be driven cordlessly by operating. The tool attachment portion 10 and the tip tool 14 attached to the tool attachment portion 10 are examples of the “working portion” in the present invention.

  A change-over switch 13 for switching the working mode of the hammer drill 1 is provided on the left side surface of the main body 2. The operator can switch the operation mode of the hammer drill 1 to any one of the rotation impact mode, the impact mode, and the rotation mode by operating the changeover switch 13. The battery mounting portion 21 of the main body 2 has a battery connection terminal portion 21A (see FIG. 3). The battery connection terminal portion 21 </ b> A has a plurality of terminals (not shown) that are electrically connected to the battery pack 15 in a state where the battery pack 15 is attached to the main body 2.

  Inside the handle 11, a trigger switch 12 and a switch mechanism 12A electrically connected to a control board unit 7 (described later) are provided. The switch mechanism 12A is for starting the motor 3 when the trigger switch 12 is pulled, that is, started (for example, when the trigger switch 12 is pushed into the handle 11 by the operator's finger). A start signal is output to the control board unit 7. Further, the switch mechanism 12A stops the output of the start signal when the pulling operation on the trigger switch 12 is released, that is, when the pulling operation is stopped (for example, when the operator releases the pulling operation by releasing the finger from the trigger switch 12). .

  As shown in FIG. 2, the main body 2 includes a motor 3, a switching circuit board 22, a drive transmission unit 4, a striking mechanism unit 5, a reciprocating motion conversion unit 6, a control board unit 7, an illumination unit 8, and a power supply unit. 9 is accommodated.

  The motor 3 is an example of a drive source and is housed in the lower part in the main body 2. The motor 3 is a brushless motor as a drive source for the hammer drill 1 and is configured to be driven by power supply from the battery pack 15 mounted on the battery mounting portion 21. The motor 3 is arranged so that the rotation shaft 31 extends in the vertical direction, and is supported rotatably with respect to the main body 2. A fan 32 is fixed to the upper end of the rotating shaft 31 of the motor 3.

  The switching circuit board 22 is an annular board in a bottom view, and has a switching circuit 22A (see FIG. 3) for driving the motor 3. The switching circuit board 22 is disposed below the motor 3, and a lower portion of the rotating shaft 31 of the motor 3 is inserted through a hole formed in a substantially center in a bottom view and penetrating in the vertical direction. Details of the switching circuit 22A will be described later.

  The drive transmission unit 4 is disposed above the motor 3 in the main body 2. The drive transmission unit 4 has an intermediate shaft 41 extending in the front-rear direction. The intermediate shaft 41 is rotatably supported with respect to the main body 2. The intermediate shaft 41 is connected to the rotation shaft 31 of the motor 3 through a plurality of gears, and can rotate by receiving the rotational force of the motor 3.

  The striking mechanism unit 5 is disposed above the drive transmission unit 4 in the main body 2. The striking mechanism unit 5 includes a cylinder 51, a piston 52, a striking element 53, and an intermediate element 54.

  The cylinder 51 has a substantially cylindrical shape extending in the front-rear direction, and is rotatably supported with respect to the main body 2 at the upper part of the main body 2. The cylinder 51 can be engaged with the intermediate shaft 41 of the drive transmission unit 4, and is configured to be rotatable by receiving the rotational force of the intermediate shaft 41 when engaged with the intermediate shaft 41. The front end portion (front end portion) of the cylinder 51 is accommodated in the tool attachment portion 10.

  The piston 52 has a substantially cylindrical shape extending in the front-rear direction, and is slidably disposed in the cylinder 51. The striker 53 is disposed in the piston 52 so as to be slidable in the front-rear direction. The intermediate element 54 is disposed in the cylinder 51 so as to be slidable in the front-rear direction in front of the striker 53. The front end of the striker 53 can come into contact with the rear end of the intermediate piece 54, and the intermediate piece 54 comes into contact with the rear end of the tip tool 14 attached to the tool attachment portion 10.

  The reciprocating motion conversion unit 6 is disposed so as to connect the drive transmission unit 4 and the striking mechanism unit 5. The reciprocating motion conversion unit 6 has an arm 61. The arm 61 extends in a direction intersecting the intermediate shaft 41 and the cylinder 51, and an upper end portion thereof is connected to a rear end portion of the piston 52 and a lower end portion thereof connected to a rear portion of the intermediate shaft 41 through a plurality of balls. The As a result, the arm 61 is configured to convert the rotational force of the motor 3 transmitted through the intermediate shaft 41 into a linear reciprocating motion in the front-rear direction and transmit it to the piston 52. The piston 52 reciprocates back and forth in the cylinder 51 by the reciprocation of the arm 61. When the air in the cylinder 51 is compressed and expanded by the reciprocating motion of the piston 52, the striker 53 reciprocates in the front-rear direction. When the striker 53 reciprocates, the front end of the striker 53 comes into contact with the rear end of the intermediate piece 54 and strikes the intermediate piece 54. When the meson 54 is hit, the front end of the meson 54 hits the rear end of the tip tool 14 attached to the tool mounting portion 10. In this way, a striking force is applied to the tip tool 14.

  The rotational force (driving force) of the motor 3 is such that the drive transmission unit 4 and the reciprocating motion conversion unit 6 are driven simultaneously or selectively, so that the striking mechanism unit 5 is rotated, hit, or rotated. Transmitted as power. Thereby, three operation modes of the hammer drill 1 are realized.

  The control board unit 7 is disposed above the battery mounting unit 21. The control board unit 7 includes a control circuit 71 (see FIG. 3) configured to perform various controls of the main body 2. The control circuit 71 is an example of the “control unit” in the present invention. Details of the control circuit 71 will be described later.

  The illumination unit 8 is disposed in the main body 2 at the front lower side of the motor 3. The front end (front end) of the illumination unit 8 is disposed so as to be exposed from the front surface of the main body 2. In the present embodiment, the illumination unit 8 is configured as an LED light. The illumination unit 8 is electrically connected to the control board unit 7, and lighting / extinguishing (operation / non-operation) is controlled by the control board unit 7. The illuminating unit 8 is configured to be able to irradiate the LED light substantially forward and upward with respect to the main body 2, that is, toward a portion (working location) where the tip tool 14 acts on the work material when lighting. The illumination unit 8 is an example of the “auxiliary unit” in the present invention, and is an example of the “illumination unit”.

  In the main body 2, an acceleration sensor 23 is provided as acceleration detection means (see FIG. 3). The acceleration sensor 23 is electrically connected to the control board unit 7 and configured to detect the acceleration of the main body 2. The acceleration sensor 23 outputs an acceleration signal corresponding to the acceleration of the main body 2 to the control board unit 7. In the current path of the motor 3, a shunt resistor 80 as a current detecting means is provided (see FIG. 3). The voltage across the shunt resistor 80 is input to the control circuit 71. The control circuit 71 detects the current flowing through the motor 3 based on the voltage across the shunt resistor 80.

  FIG. 3 is a circuit block diagram showing an electrical configuration of the hammer drill 1. A battery pack 15 serving as a driving power source for the hammer drill 1 mainly includes a battery cell set 151 and a battery protection IC 150. The battery pack 15 includes a casing (not shown), and a tool connection portion that can be connected to the hammer drill 1 is formed in the casing.

  The battery cell set 151 is a set in which battery cells are connected in series, and is accommodated in a casing (not shown) of the battery pack 15. It is connected to the discharge plus terminal of the battery cell having the highest potential in the battery cell set 151. The minus terminal of the lowest battery cell in the battery cell set 151 is connected to the discharge minus terminal via the shunt resistor 152. The positive terminal and the negative terminal of each battery cell are connected to the protection IC 150, and all voltages are individually monitored by the protection IC 150. In the present embodiment, the battery cell is a lithium secondary battery, and the rated voltage is 3.6V.

  Here, the type (battery type) of the battery pack will be described. The battery type is a classification of the battery pack, and is classified according to the characteristics of the battery set built in the battery pack. The characteristics of the battery set include the rated voltage, rated discharge current, rated temperature, overdischarge threshold based on the rated voltage, overcurrent threshold based on the rated discharge current, and the maximum allowable temperature based on the rated temperature. It is the characteristic which the whole battery group which should be considered in charge / discharge control, such as. Therefore, if the battery type is different, the characteristics, that is, the overcurrent threshold, the allowable maximum temperature, and the like are different, and if the battery type is the same, the characteristics are also the same. If the battery type is found, the characteristics are found.

  Specifically, the number of battery cells included in the battery set, the connection configuration, that is, the number of parallel connections and the number of series connections, the rated voltage per cell, the rated discharge current (rated discharge capacity), the allowable maximum temperature, and the like are different. The battery type is different. For example, even if the rated voltage per cell is the same and the battery set has 10 battery cells, a configuration in which 5 battery cells connected in series are connected in parallel (5 series) A battery pack having two battery sets and a battery pack having 10 battery cells connected in series (10 in parallel) have a rated voltage and a rated discharge current in the entire battery set. The battery type is different because of the different characteristics.

  The battery side terminal portion is provided at a connection portion of a casing (not shown), and includes a discharge plus terminal, a discharge minus terminal, a battery protection signal terminal, and a battery type discrimination terminal. When the battery pack 15 is connected to the hammer drill 1, four terminals are connected to predetermined terminal portions provided on the hammer drill 1.

  The shunt resistor 152 is a resistor used for detecting a current flowing through the battery cell set 151 during charge / discharge, and both ends thereof are connected to the protection IC 150.

  The battery type discrimination terminal is connected to the ground via the battery type discrimination resistor 153. The battery type discrimination resistor 153 has a specific resistance value determined for each battery type. When the battery pack 15 is connected to the hammer drill 1, the hammer drill 1 reads the resistance value of the battery type determination resistor 153 and determines the battery type of the battery pack 15. Details of the battery type discrimination by the hammer drill 1 will be described later. The battery type determination resistor 153 may not be provided, and the battery type may be determined based on a voltage drop when the motor 3 is started.

  The protection IC 150 is an IC that individually monitors the voltage of each battery cell constituting the battery cell set 151, and is provided for protection from overdischarge and overcurrent. The protection IC 150 outputs a discharge stop signal from the battery protection signal terminal to the hammer drill 1 when there is even one battery cell that is determined to be in an overdischarged state. Further, the protection IC 150 takes in the value of the voltage drop of the shunt resistor 152, calculates the value of the current from the value of the voltage drop, and when it is determined that the current is excessive, the discharge stop signal is sent from the battery protection signal terminal to the hammer drill. Output to 1.

  The main body 2 of the hammer drill 1 includes a plus line 24, a GND line 25, a first signal line 26, a second signal line 27, the battery connection terminal portion 21A, the switching circuit 22A, the motor 3, the control circuit 71, and a switch. The mechanism 12A, the acceleration sensor 23, and the illumination unit 8 are included.

  One end of each of the plus line 24, the GND line 25, the first signal line 26, and the second signal line 27 is connected to the battery connection terminal portion 21A, and the other end is connected to the control circuit 71. The In a state where the battery pack 15 is mounted on the battery mounting portion 21, the voltage of the battery pack 15 is applied between the plus line 24 and the GND line 25. When the battery pack 15 outputs a battery protection signal, the battery protection signal is input to the control circuit 71 via the first signal line 26. In this case, the control circuit 71 stops the motor 3.

  In addition, the battery type determination signal is input to the control circuit 71 via the second signal line 27. The switching circuit 22 </ b> A is a circuit that supplies the electric power of the battery pack 15 to the motor 3, and is connected between the plus line 24 and the GND line 25 and the motor 3. The switching circuit 22A has six switching elements (not shown). In the present embodiment, the six switching elements are six FETs. The six FETs are connected in a three-phase bridge format, each gate is connected to the control circuit 71, and each drain or each source is connected to the motor 3. The six switching elements FET perform a switching operation for rotating the rotation shaft 31 of the motor 3 in a predetermined rotation direction based on a drive signal (gate signal) output from the control circuit 71.

  The control circuit 71 is a circuit that controls the main body of the hammer drill 1, and includes a central processing unit (CPU) that performs calculation based on a processing program and various data used for main body control, the processing program, various data, various threshold values, and the like. A storage unit having a ROM (not shown) for storing the data and a RAM (not shown) for temporarily storing data, and a time measuring unit for measuring time are included. In the present embodiment, the control circuit 71 includes a microcomputer as a calculation unit.

  The control circuit 71 performs drive control on the motor 3 as main body control. In the drive control for the motor 3, the control circuit 71 switches a drive signal for alternately switching the FET to be conducted among the six FETs based on a rotation position signal output from a rotation position detection circuit (not shown). Output to the circuit 22A. Thereby, the rotating shaft 31 of the motor 3 is rotated in a predetermined rotation direction. Further, the control circuit 71 adjusts the electric power supplied to the motor 3 and controls the rotational speed of the rotary shaft 31. The control circuit 71 controls the period from the start of the motor 3 until reaching a predetermined preset rotational speed as the rotational speed control, and after reaching the predetermined preset rotational speed, The constant rotation speed control is performed to maintain the set rotation speed. The rotational speed is controlled by outputting a drive signal for driving (conducting) predetermined three FETs of the switching circuit 22A as a PWM drive signal (PWM control). Further, the control circuit 71 controls the start / stop of the motor 3 based on the start signal output from the switch mechanism 12A.

  As the main body control, the control circuit 71 detects the acceleration of the main body 2 by the acceleration sensor 23 while the motor 3 is being driven. The detected acceleration is used in the control circuit 71 to determine whether or not it is necessary to prevent the main body from being swung. That is, the control circuit 71 stops the motor 3 when the acceleration detected by the acceleration sensor 23 is greater than or equal to the first threshold value. As will be described later, the first threshold value is determined (changed) in accordance with the type of the battery pack 15 attached to the main body 2. The type of the battery pack 15 for determining the first threshold includes information necessary for specifying the weight of the battery pack 15, and is, for example, a combination of the rated voltage and the rated discharge capacity of the battery pack 15. Alternatively, the number of battery cells incorporated in the battery pack 15 may be used, or the weight of the battery pack 15 may be directly used. The first threshold value when the weight of the battery pack 15 is large is smaller than the first threshold value when the weight of the battery pack 15 is small (see FIG. 4).

  The control circuit 71 detects the current flowing through the motor 3 by the voltage across the shunt resistor 80 during the driving of the motor 3 as the main body control. The detected current is used in the control circuit 71 to determine whether or not it is necessary to prevent the main body from being swung. That is, the control circuit 71 stops the motor 3 when the current detected by the voltage across the shunt resistor 80 is equal to or greater than the second threshold value. As will be described later, the second threshold is determined (changed) according to the type of the battery pack 15 attached to the main body 2. The type of the battery pack 15 for determining the second threshold includes the rated voltage of the battery pack 15, and may be, for example, the rated voltage of the battery pack 15 or a series of battery cells built in the battery pack 15. It may be the number of connections. The second threshold value when the rated voltage of the battery pack 15 is high is larger than the second threshold value when the rated voltage of the battery pack 15 is low (see FIG. 4).

  FIG. 4 is an operation condition table (blocking condition table) for the main body swing prevention function of the hammer drill 1, and the motor 3 determined for each type (battery type) of the battery pack 15 that can be attached to and detached from the hammer drill 1 is stopped. It is a table | surface which shows an example of the acceleration value discrimination | determination conditions and current value discrimination | determination conditions which determine whether or not. The table shown in FIG. 4 is stored in the storage unit of the control circuit 71. As shown in FIG. 4, the operating condition of the main body swing prevention function (main body shake prevention function) is different for each battery type, and is detected by the acceleration sensor 23 in consideration of the characteristics and weight for each battery type. The acceleration value and the current value flowing through the motor 3 are determined by two parameters.

  The acceleration value condition is set as the first threshold value in consideration of the weight of the battery pack 15 (the number of battery cells), and the current value is set as the second threshold value according to the voltage specification of the battery pack 15. This condition must be set in consideration of actual measurement values.

  FIG. 5 is a waveform diagram illustrating an example of temporal changes in acceleration and current when the main body 2 of the hammer drill 1 is swung by the lock of the working unit when the motor 3 is started. From this operation waveform, it can be seen that the acceleration value increases because the main body 2 is more easily swung as the weight of the battery pack 15 attached to the main body 2 decreases. The current value increases as the rated voltage of the battery pack 15 attached to the main body 2 increases. Based on these, the body swing prevention function operating condition is determined as shown in FIG. 4, for example. In the example of FIG. 4, when the number of battery cells of the battery pack 15 is doubled, the condition is set such that the acceleration threshold value (first threshold value) for stopping the motor 3 is halved. Further, when the rated voltage of the battery pack 15 is doubled, the condition is determined so that the current threshold (second threshold) for stopping the motor 3 is doubled. Note that the condition shown in FIG. 4 is a condition in the sense that the motor 3 is stopped (the body swinging prevention function is activated) if any one of the acceleration and current values is satisfied.

  FIG. 6 is a control flowchart of the hammer drill 1. This flowchart shows the flow of main body control by the control circuit 71 (control board unit 7).

  When the battery pack 15 is attached to the battery attachment portion 21, power is supplied to the control circuit 71, and the control circuit 71 starts main body control. When starting the main body control, the control circuit 71 determines whether or not a starting operation (pulling operation) has been performed on the trigger switch 12 (S101). Specifically, the control circuit 71 determines whether or not a start operation has been performed on the trigger switch 12 based on the presence or absence of a start signal from the switch mechanism 12A.

  When the control circuit 71 determines that the starting operation is not performed on the trigger switch 12 (S101: NO), the control circuit 71 performs the determination of S101 again. That is, the control circuit 71 waits until the start operation for the trigger switch 12 is performed while repeating the determination of S101. On the other hand, when it is determined that the starting operation has been performed on the trigger switch 12 (S101: YES), the voltage value of the battery type determination signal is detected (S102), and the mounted battery type is determined (S103). . Specifically, the control circuit 71 divides the reference voltage by the resistance value of the battery type discrimination resistor 153 having a unique value for each battery type and the voltage dividing resistor provided in the control circuit 71, and The pressed voltage is detected as a battery type discrimination voltage, and the battery type is discriminated.

  Next, the control circuit 71 sets the main body shake prevention function operating condition from the main body shake determination table (FIG. 4) according to the determined battery type of the battery pack 15 (S104). Specifically, the control circuit 71 refers to the cutoff condition table shown in FIG. 4 stored in the ROM of the storage unit, and sets the main body shake prevention function operating condition suitable for the determined battery type.

  Next, the control circuit 71 starts driving the motor 3 (S105). When the driving of the motor 3 is started, the tip tool 14 is driven, and the driven tip tool 14 is brought into contact with the work material, thereby realizing work such as drilling the work material. Next, the control circuit 71 detects a current value flowing through the motor 3 after the start of driving of the motor 3 (S106), and detects an acceleration value by the acceleration sensor 23 (S107). Then, the control circuit 71 compares the body shake prevention function operating condition set in S104 with the current value and acceleration value detected in S106 and S107, and if the body shake prevention function operation condition is satisfied (S108). : YES), the drive of the motor 3 is stopped (S111). Note that the determination in S108 is made based on whether or not at least one of the current value and the acceleration value satisfies the condition.

  If the operating condition for the main body shaking prevention function is not satisfied (S108: NO), the process proceeds to the next step, and a battery protection signal from the battery pack 15 is detected (S109). If the battery protection signal is output (S109: YES), the process proceeds to S111 and the motor 11 is stopped. If the battery protection signal is not output (S109: NO), the process proceeds to the next step, and it is determined whether the starting operation for the trigger switch 12 has been released (S110). Determination of cancellation of the start operation is made based on the presence or absence of a start signal from the switch mechanism 12A. Specifically, when the output of the start signal by the switch mechanism 12A is stopped, the control circuit 71 determines that the start operation for the trigger switch 12 has been released. When it is determined that the starting operation for the trigger switch 12 has been released (S110: YES), the driving of the motor 3 is stopped (S111). If it is determined that the starting operation for the trigger switch 12 has not been released (S110: NO), the process returns to S105 again, and the processes from S105 to S110 are repeated.

  As described above, according to such a configuration, it is possible to prevent the hammer drill 1 from being swung around because the tip tool 14 driven by the motor 3 is locked during the operation.

  According to the present embodiment, the following effects can be achieved.

(1) In the configuration including the acceleration sensor 23 for detecting the acceleration of the main body 2 and stopping the motor 3 when the detected acceleration is equal to or higher than the first threshold, the first threshold is determined according to the type of the battery pack 15. Even if the type of the battery pack 15 to be mounted changes, the function of preventing the shake of the main body 2 can be appropriately executed. Specifically, for example, if the first threshold value is constant and is set to a small value in accordance with the heavy battery pack 15, the main body 2 is not shaken when the low weight battery pack 15 is attached. Regardless, the risk that the shake prevention function operates and the motor 3 stops (risk of malfunction) increases. On the other hand, if the first threshold value is constant and is set to be large in accordance with the battery pack 15 having a small weight, when the battery pack 15 having a large weight is attached, the main body 2 is shaken despite being shaken. The risk that the preventable function does not operate and the motor 3 does not stop increases (risk of non-operation). In contrast, in the present embodiment, the first threshold value is variably set so as to decrease as the battery pack 15 to be loaded becomes heavier. The prevention function can be appropriately executed.

(2) In the configuration including the shunt resistor 80 for detecting the current flowing through the motor 3 and stopping the motor 3 when the detected current is equal to or greater than the second threshold, the second threshold is determined according to the type of the battery pack 15. Therefore, even if the type of the battery pack 15 to be mounted changes, the shake preventing function of the main body 2 can be appropriately executed. Specifically, for example, when the second threshold is constant and is set to be small according to the battery pack 15 having a low rated voltage, the main body 2 is not shaken when the battery pack 15 having a high rated voltage is attached. Nevertheless, the risk that the shaking prevention function operates and the motor 3 stops (risk of malfunction) increases. On the other hand, if the second threshold value is constant and is set to be large according to the battery pack 15 having a high rated voltage, when the battery pack 15 having a low rated voltage is attached, the main body 2 is swung. The risk that the prevention of shaking is not activated and the motor 3 does not stop increases (risk of malfunction). On the other hand, in the present embodiment, the second threshold value is variably set so as to increase as the rated voltage of the battery pack 15 to be attached increases, so that the malfunction risk and malfunction risk described above are reduced. Thus, it is possible to appropriately execute the shake preventing function 2.

  The present invention has been described above by taking the embodiment as an example. However, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way. Hereinafter, modifications will be described.

  In the embodiment, the hammer drill 1 is described as an example of the work tool. However, the present invention is also applicable to a work tool driven by a motor other than the hammer drill, for example, a drilling tool such as an electric hammer, an electric drill, a vibration drill, and a driver drill. Is possible.

DESCRIPTION OF SYMBOLS 1 ... Hammer drill, 2 ... Main body, 3 ... Motor, 4 ... Drive transmission part, 5 ... Stroke mechanism part, 6 ... Reciprocating motion conversion part, 7 ... Control board part, 8 ... Illumination part, 9 ... Electric power supply part, 12 ... Trigger switch, 12A ... switch mechanism, 15 ... battery pack, 21A ... battery connection terminal, 22A ... switching circuit, 23 ... acceleration sensor, 26 ... first signal line, 27 ... second signal line

Claims (5)

A main body having a battery mounting portion for detachably mounting the battery pack;
A motor that operates with power supplied from the battery pack;
Acceleration detecting means for detecting the acceleration of the main body;
A controller that stops the motor when the detected acceleration is greater than or equal to a first threshold,
The work tool according to claim 1, wherein the first threshold value is determined according to a type of the battery pack.   The work tool according to claim 1, wherein the type of the battery pack includes at least one of a rated voltage and a rated discharge capacity of the battery pack, a weight of the battery pack, and a number of battery cells built in the battery pack. .   The work tool according to claim 1, wherein the first threshold value when the weight of the battery pack is large is smaller than the first threshold value when the weight of the battery pack is small. Comprising current detection means for detecting the current flowing through the motor;
The control unit stops the motor when the detected current is equal to or greater than a second threshold,
The work tool according to any one of claims 1 to 3, wherein the second threshold value is determined according to a type of the battery pack. The type of the battery pack includes information capable of specifying the rated voltage of the battery pack,
The work tool according to claim 4, wherein the second threshold value when the rated voltage of the battery pack is high is larger than the second threshold value when the rated voltage of the battery pack is low.

Images