JP7180746B2 - electric work machine - Google Patents

Description

The present invention relates to an electric working machine such as a hammer drill.

Electric working machines such as hammer drills are driven by a motor to rotate a tip tool to form a hole in a workpiece (e.g., concrete, steel, wood, etc.), or to crush by applying a striking force to the tip tool. You can In such an electric working machine, there is a case where the tip tool is caught in a hard part of the workpiece during work and the tip tool is locked. When the tip tool is locked, kickback occurs in which the housing is swung around by the drive of the tip tool. In preparation for the occurrence of kickback, a method of detecting the acceleration in the rotational direction generated in the housing using an acceleration sensor as described in Patent Document 1 below, and a method of detecting a decrease in the number of rotations of the motor using a Hall IC. There are methods to do so. When using the method of detecting acceleration, it is necessary to install an acceleration sensor on the electric working machine, which increases the manufacturing cost due to the increase in the number of parts, and there is a risk that the kickback cannot be detected normally due to the failure of the acceleration sensor. be. On the other hand, when the method of detecting the number of revolutions is used, the Hall IC used for controlling the rotation of the motor can be used, so the number of parts does not increase, and the risk of not being able to detect kickback normally due to failure can be suppressed. Therefore, from the viewpoint of manufacturing cost and product durability, it is preferable to use rotation speed rather than acceleration for kickback detection.

JP 2019-005847 A

In electric work machines, when the work environment is cold, the viscosity of the lubricant applied to the drive parts increases, which may cause the behavior of the motor to start up to differ from that at room temperature, resulting in poor workability. sometimes decreased. For example, in a hammer drill, which is an example of an electric working machine, swinging detection is performed to stop the motor when swinging of the main body is detected in order to suppress swinging (kickback) of the main body when the motor is started. Detection of being swung is determined by using a Hall IC and determining whether or not it is detected that the number of revolutions of the motor is below a threshold value. However, when the temperature is low, the viscosity of the lubricant increases, and the rate of increase in the rotation speed of the motor becomes slower than when it is at room temperature. There is a risk that the motor will stop because it will erroneously determine that it has been swung around. If the motor is driven and warmed up for a predetermined time or longer, the lubricant will be warmed and the above problem will be solved. There was a problem that the motor could not be warmed up even after repeated starting. In addition, when the temperature of the lubricant is low, the load on the motor also increases. I was afraid it would stop.

SUMMARY OF THE INVENTION The present invention has been made in recognition of such circumstances, and an object thereof is to provide an electric working machine capable of suppressing deterioration in workability when the work environment is at low temperature.

One aspect of the present invention is an electric working machine. This electric work machine
a motor;
a control unit that controls driving of the motor;
A rotation speed detection unit that detects the rotation speed of the motor,
The control unit performs a first start-up control when a low temperature determination condition indicating that the ambient temperature of the motor is low is not satisfied in the start control for increasing the rotation speed of the motor , and the low temperature determination condition is satisfied. If it is, perform the second startup control,
The control unit
In the first startup control, when a first predetermined condition is satisfied, the rotation speed of the motor is reduced,
In the second startup control, even if the first predetermined condition is satisfied, the number of revolutions of the motor is not reduced,
The first predetermined condition includes that the number of rotations of the motor is less than a predetermined number of rotations when a predetermined time has elapsed since the start of driving of the motor.

The low temperature determination condition may include that the number of revolutions of the motor is less than the first number of revolutions when a first predetermined time has passed since the start of driving of the motor.

A temperature detecting means for detecting the ambient temperature may be provided, and the low temperature determination condition may include a condition regarding a value detected by the temperature detecting means.

A housing that accommodates the motor and the control unit, and a tool tip operated by the driving force of the motor, wherein the control unit is operated by the operation of the tool tip when the first predetermined condition is satisfied. It may be determined that the housing has been swung around.

A clutch section may be provided for disconnecting a transmission path for transmitting the driving force of the motor to the tool bit when the load applied to the tool bit is equal to or greater than a predetermined value.

In the second startup control, the control unit reduces the rotation speed of the motor when a second predetermined condition is satisfied ,
The predetermined time is a second predetermined time,
The predetermined number of rotations is a second number of rotations,
The first predetermined condition includes that the number of rotations of the motor is less than the second number of rotations when a third predetermined time has elapsed from the start of driving of the motor,
The second predetermined condition may include that the rotation speed of the motor is less than a third rotation speed lower than the second rotation speed when the third predetermined time has elapsed from the start of driving of the motor. .

The control unit may moderately increase the effective value of the voltage applied to the motor in the second start-up control as compared with the first start-up control.

Any combination of the above constituent elements, and conversion of expressions of the present invention between methods and systems are also effective as embodiments of the present invention.

Advantageous Effects of Invention According to the present invention, it is possible to provide an electric working machine capable of suppressing a decrease in workability when the working environment is at low temperature.

1 is a perspective view of an electric operating machine 1 according to Embodiment 1 of the present invention; FIG. FIG. 2 is a side cross-sectional view of the electric working machine 1; FIG. 2 is a circuit block diagram of the electric operating machine 1; 4 is a control flowchart of the electric operating machine 1; 4 is a graph showing changes in the number of revolutions of the motor 6 in the electric working machine 1 from start to 120 msec in various cases, together with the first number of revolutions for low temperature determination and the second number of revolutions for kickback determination at room temperature. . Regarding the second embodiment of the present invention, a graph obtained by adding the rotation speed change of the motor 6 at low temperature and kickback occurrence and adding the third rotation speed for kickback determination at low temperature to FIG. 5 . 6 is a control flowchart of an electric operating machine according to Embodiment 2. FIG.

Preferred embodiments of the present invention will be described in detail below with reference to the drawings. The same or equivalent constituent elements, members, processes, etc. shown in each drawing are denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. Moreover, the embodiments are illustrative rather than limiting the invention, and not all features and combinations thereof described in the embodiments are necessarily essential to the invention.

(Embodiment 1) This embodiment relates to an electric operating machine 1. FIG. This electric working machine 1 is characterized in that the starting control of the motor 6 is differentiated depending on whether the ambient temperature of the motor 6 is low or not, thereby suppressing erroneous kickback detection at low temperatures. Startup control refers to control in the process of increasing the rotation speed of the motor 6 from the start of driving of the motor 6 to the target rotation speed.

The mechanical configuration of the electric working machine 1 will be described with reference to FIGS. 1 and 2. FIG. FIG. 2 defines the front-rear and up-down directions of the electric working machine 1 . The electric working machine 1 is a corded hammer drill that operates with power supplied from an external AC power supply, and by applying a rotational force and a striking force to the tip tool 19, a work material such as concrete or stone is scraped. It can be used for drilling, drilling, and crushing. An outer shell of the electric working machine 1 is composed of a housing 2 and a gear case 3 . The housing 2 is, for example, a resin molding. The gear case 3 is made of metal such as aluminum. A side handle 4 is provided on the gear case 3 .

The housing 2 has a motor accommodating portion 2a that accommodates the motor 6 and the like, and a handle portion 2b that is gripped by an operator. An operation panel 8 for switching the rotation speed of the motor 6 by the operator is provided on the upper surface of the motor housing portion 2a. The operation panel 8 includes a speed switching button 8a and a speed display portion 8b. The operator can switch the rotation speed of the motor 6 by the speed switching button 8a. The current set rotational speed of the motor 6 is displayed on the speed display section 8b such as an LED.

A trigger switch 7 is provided at the upper end of the handle portion 2b so that the operator can instruct the motor 6 to be driven or stopped. A power cord 27 for connecting to an external AC power source extends from the lower end of the handle portion 2b. A filter substrate 21 is provided in the handle portion 2b. The motor 6 is housed and held in the motor housing portion 2a. An AC/DC conversion circuit board 29 is provided above and behind the motor 6 . A control board 22 and an inverter board 25 are provided in front of the stator of the motor 6 . An output shaft 6 a of the motor 6 passes through the control board 22 and the inverter board 25 . A cooling fan 23 is provided in front of the output shaft 6a. The fan 23 rotates integrally with the output shaft 6a. A plurality of magnets 24 are provided in the fan 23 . The magnet 24 faces the rear of the fan 23 and faces the control board 22 .

The gear case 3 accommodates a power transmission mechanism that transmits the rotation of the motor 6 to drive (rotate and strike) the tool bit 19 . Since the configuration of this power transmission mechanism is well known, a brief description will be given below. A gear 9 is provided at the front end of the output shaft 6 a of the motor 6 . A gear 10 that meshes with the gear 9 is provided at the rear end of the intermediate shaft 11 . The intermediate shaft 11 is provided with a first clutch member 12, a second clutch member 13, and a reciprocating bearing 26 as a reciprocating motion conversion mechanism. The first clutch member 12 switches whether to transmit the rotation of the intermediate shaft 11 to the reciprocating bearing 26 . The second clutch member 13 switches whether to transmit the rotation of the intermediate shaft 11 to the gear 14 provided on the outer peripheral portion of the cylinder 28 . Transmission and interruption of rotation by the first clutch member 12 and the second clutch member 13 can be switched by an operator using a change lever (not shown) facing the outside of the gear case 3 .

The reciprocating bearing 26 converts the rotation of the intermediate shaft 11 into back and forth reciprocating motion and transmits the motion to the piston 15 . Piston 15 is provided within cylinder 28 . Inside the piston 15, an air chamber 16 and a striker 17 are provided in order from the rear. A second hammer (meson) 18 is provided in front of the striker 17 . The forward movement of the piston 15 compresses the air in the air chamber 16, and the pressure (positive pressure) of the compressed air moves the striker 17 forward. A striker 17 moving forward strikes a second hammer 18, and the second hammer 18 moving forward strikes a tip tool 19 with the impact force. The rearward movement of the piston 15 causes the air in the air chamber 16 to expand, and the pressure (negative pressure) of the expanded air causes the striker 17 to move rearward. In this way, the striker 17 is reciprocated back and forth by fluctuations (compression/expansion) in the air pressure in the air chamber 16 due to the reciprocating motion of the piston 15 , and the striker 17 hits the second hammer 18 , which in turn moves the tip tool 19 . hit the

The cylinder 28 is rotationally driven by the rotation of the gear 14 to which the rotation of the intermediate shaft 11 is transmitted. The tool holding portion 5 provided in front of the cylinder 28 and the tip tool 19 held by the tool holding portion 5 rotate together with the cylinder 28 . A gear 14 and a slip clutch mechanism 20 are provided on the outer circumference of the cylinder 28 . The slip clutch mechanism 20 slips and cuts off rotation transmission between the gear 14 and the cylinder 28 when the torque of the gear 14 exceeds a certain level.

The electric working machine 1 has three operation modes, an impact mode, a rotary impact mode, and a rotation mode. In the impact mode, rotation transmission by the first clutch member 12 is effective, and rotation transmission by the second clutch member 13 is ineffective. In the rotational impact mode, rotation transmission of both the first clutch member 12 and the second clutch member 13 is effective. In the rotation mode, rotation transmission by the first clutch member 12 is disabled and rotation transmission by the second clutch member 13 is enabled.

FIG. 3 is a circuit block diagram of the electric working machine 1. As shown in FIG. The AC power supply 31 is an external power supply that supplies electric power to the electric working machine 1 . The filter circuit 32 is provided on the filter substrate 21 of FIG. 2, and is provided between connection terminals with the AC power supply 31 on the circuit. The filter circuit 32 consists of a capacitor C1 and an inductor L1. The filter circuit 32 filters high-frequency noise generated by switching elements such as an inverter circuit 35 and an AC/DC conversion circuit 33, which will be described later, so as not to affect the AC power supply 31 side.

The AC/DC conversion circuit 33 is provided on the AC/DC conversion circuit board 29 in FIG. The AC/DC conversion circuit 33 converts the AC voltage supplied from the AC power supply 31 into a DC voltage using a diode bridge DB, and after the conversion smoothes the DC voltage using an electrolytic capacitor C2. The control circuit voltage supply circuit 34 converts the voltage rectified and smoothed by the diode bridge DB and the electrolytic capacitor C2 into a DC voltage of a predetermined voltage and supplies the DC voltage to the control circuit section 40 .

The inverter circuit 35 is a circuit in which the switching elements Q1 to Q6 are three-phase bridge-connected, and switches the output voltage of the AC/DC conversion circuit 33 and supplies it to the stator coil of the motor 6 . The inverter circuit 35 is provided on the inverter board 25 in FIG. A resistor R is provided in the current path of the motor 6 . A temperature detection element (temperature detection means) 48 such as a thermistor is provided near the inverter circuit 35 or near the motor 6 and transmits a temperature detection value to the microcomputer 45 . The three Hall ICs 47 are provided on the control board 22 in FIG. 2 and face the magnets 24 provided on the fan 23 . The Hall IC 47 outputs a signal corresponding to the rotation of the fan 23, that is, the rotation of the motor 6. FIG.

Each circuit component constituting the control circuit section 40 is provided on the control board 22 in FIG. In the control circuit section 40, a motor current detection circuit 41 detects the current of the motor 6 from the voltage across the resistor R, and transmits it to a microcomputer (microcontroller) 45 as a control section. The step-down circuit 42 steps down the output voltage of the control circuit voltage supply circuit 34 and supplies it to the microcomputer 45 . The control signal output circuit 43 applies a control signal (drive signal), eg, a PWM signal, to each gate of the switching elements Q1 to Q6 of the inverter circuit 35 under the control of the microcomputer 45 . A Hall IC signal detection circuit 44 receives the output signal of the Hall IC 47 and transmits a signal corresponding to the rotational position of the motor 6 to the microcomputer 45 . The microcomputer 45 includes a CPU, timer, ROM, RAM, etc., and controls the control signal output circuit 43 according to the current, rotational position, and temperature of the motor 6 to control the drive of the motor 6 .

FIG. 4 is a control flowchart of the electric operating machine 1. FIG. This flowchart is started when the operator turns on the trigger switch 7 . The microcomputer 45 starts driving the motor 6 (S1). When 30ms as the first predetermined time has elapsed since the start of driving the motor 6 (S3), the microcomputer 45 confirms whether or not the number of rotations of the motor 6 is 1,800 rpm or more as the first number of rotations (S5). When the number of rotations of the motor 6 is 1,800 rpm or more (Yes in S5), the microcomputer 45 determines that the ambient temperature of the motor 6 is normal temperature, and 90 ms has passed as the second predetermined time from the start of driving the motor 6. Then (S7), it is checked whether or not the rotation speed of the motor 6 is 3,500 rpm or less as the second rotation speed (S9). When the number of rotations of the motor 6 is 3,500 rpm or less (Yes in S9), the microcomputer 45 determines that the tip tool 19 has caused a kickback in which the main body is swung, and stops the motor 6 (S11).

If the number of rotations of the motor 6 is not 1,800 rpm or more when 30ms has passed since the start of driving the motor 6 (No in S5), the microcomputer 45 determines that the ambient temperature of the motor 6 is low, and the trigger switch 7 is turned on. The motor 6 continues to be driven unless it is turned off (No at S13), and when the trigger switch 7 is turned off (Yes at S13), the motor 6 is stopped (S15). If the number of rotations of the motor 6 is not 3,500 rpm or less when 90ms has passed since the start of driving the motor 6 (No in S9), the microcomputer 45 determines that kickback has not occurred and turns off the trigger switch 7. The driving of the motor 6 is continued unless it becomes (No of S13), and when the trigger switch 7 is turned off (Yes of S13), the motor 6 is stopped (S15).

FIG. 5 shows changes in the number of revolutions of the motor 6 in the electric working machine 1 from start to 120 msec after lapse of 120 msec in various cases. It is a graph shown with a number. Since there are various cases in which the rotation speed of the motor 6 changes when kickback occurs, three patterns are shown together in FIG. Normal temperature and low temperature are descriptions related to the ambient temperature of the motor 6 . When the motor 6 is not driven for a long time, the ambient temperature of the motor 6 matches the ambient temperature, but when the motor 6 is driven, the ambient temperature of the motor 6 becomes higher than the ambient temperature. In the case of normal start-up at low temperature, the increase in rotation speed of motor 6 is slower than in the case of normal start-up at normal temperature because the viscosity of the lubricant (grease) applied to the power transmission mechanism is low. This is because it is higher than at room temperature.

As shown in FIG. 5, when 30 ms as the first predetermined time has passed since the start of driving the motor 6, the rotation speed of the motor 6 is 1,800 rpm or more, which is the first rotation speed, except for normal startup at low temperatures. Become. On the other hand, at the same point in time, the number of rotations of the motor 6 is less than 1,800 rpm in normal starting at low temperatures. Therefore, the microcomputer 45 determines whether the rotation speed of the motor 6 is 1,800 rpm or more when 30 ms has passed since the start of driving the motor 6 (corresponding to S4 in FIG. 4), that is, whether the ambient temperature of the motor 6 is low. Whether the ambient temperature of the motor 6 is room temperature or low is determined depending on whether or not the low temperature determination condition indicating that is satisfied. Specifically, the microcomputer 45 determines that the ambient temperature of the motor 6 is normal temperature when the number of revolutions of the motor 6 is 1,800 rpm or more when 30 ms have passed since the start of driving the motor 6, and performs the first start control. I do. The microcomputer 45 determines that the ambient temperature of the motor 6 is low when the rotational speed of the motor 6 at the same time is less than 1,800 rpm, and performs the second startup control.

As shown in FIG. 5, when 90ms as the second predetermined time has passed since the start of driving the motor 6, the number of rotations of the motor 6 exceeds 3,500 rpm as the second number of rotations in normal start-up at room temperature. On the other hand, at the same time, the number of revolutions of the motor 6 becomes 3,500 rpm or less except when kickback occurs at room temperature and when the engine is not normally started at low temperature. Therefore, when the ambient temperature of the motor 6 is normal temperature, that is, in the first startup control, the microcomputer 45 determines whether the number of rotations of the motor 6 exceeds 3,500 rpm when 90 ms have passed since the start of driving the motor 6. (corresponding to S9 in FIG. 4, whether or not the first predetermined condition is satisfied), it is determined whether or not kickback has occurred. Specifically, if the number of revolutions of the motor 6 exceeds 3,500 rpm when 90 ms have passed since the start of driving the motor 6, the microcomputer 45 determines that there is no kickback and continues driving the motor 6. The microcomputer 45 determines that kickback occurs when the rotation speed of the motor 6 at the same time is 3,500 rpm or less, and reduces the rotation speed of the motor 6 . In step S11 of FIG. 4, the motor 6 is stopped as an example of reducing the rotational speed of the motor 6 (the rotational speed of the motor 6 is reduced to 0). On the other hand, when the ambient temperature of the motor 6 is low, that is, in the second startup control, the microcomputer 45 determines whether or not kickback occurs based on the number of revolutions of the motor 6 when 90ms have passed since the start of driving the motor 6. do not have. As a result, even if the number of rotations of the motor 6 is 3,500 rpm or less when 90 ms has passed since the start of driving the motor 6 during normal start-up at low temperatures, the microcomputer 45 will erroneously determine that kickback has occurred. will not be done. Even in normal start-up at low temperatures, if the rotation speed of the motor 6 is 3,500 rpm or less when 90 ms has elapsed since the start of driving the motor 6, the rotation speed may be slightly decreased.

According to this embodiment, when the ambient temperature of the motor 6 is low, the microcomputer 45 does not determine whether or not kickback occurs based on the number of revolutions of the motor 6 when 90 ms have passed since the start of driving the motor 6. Therefore, it is possible to prevent the motor 6 from stopping due to erroneous detection that kickback has occurred even though kickback has not occurred. Thereby, it is possible to suppress deterioration of workability when the working environment is at low temperature.

In the present embodiment, instead of judging whether the ambient temperature of the motor 6 is low or not based on whether the number of revolutions of the motor 6 is 1,800 rpm or more at the time when 30 ms has passed since the start of driving the motor 6, Alternatively, it may be determined whether or not the ambient temperature of the motor 6 is low from the output signal of the temperature detection element 48 . Even if the temperature detection element 48 is located near the inverter circuit 35, the temperature of the inverter circuit 35 and the ambient temperature of the motor 6 are correlated. is low temperature.

(Embodiment 2) The mechanical configuration and circuit configuration of the electric working machine of the present embodiment are common to the electric working machine 1 of Embodiment 1 shown in Figs. 1 to 3 . In the electric working machine of the present embodiment, unlike the electric working machine 1 of the first embodiment, when the ambient temperature of the motor 6 is low, the presence or absence of kickback is determined under conditions different from those at room temperature. The following description focuses on differences from the first embodiment. FIG. 6 relates to Embodiment 2 of the present invention, and in addition to FIG. is a graph with the addition of

When 90ms, which is the third predetermined time, has passed since the start of driving the motor 6, the number of rotations of the motor 6 exceeds 2,000 rpm, which is the third number of rotations, in normal start-up at low temperatures. On the other hand, at the same time, when kickback occurs at low temperature, the rotation speed of the motor 6 becomes 2,000 rpm or less. For this reason, when the ambient temperature of the motor 6 is low, that is, in the second startup control, the microcomputer 45 determines whether the rotation speed of the motor 6 exceeds 2,000 rpm when 90 ms have passed since the start of driving the motor 6. (whether the second predetermined condition is satisfied) determines whether or not kickback has occurred. Specifically, if the rotation speed of the motor 6 exceeds 2,000 rpm when 90 ms have passed since the start of driving the motor 6, the microcomputer 45 determines that there is no kickback and continues driving the motor 6. The microcomputer 45 determines that kickback occurs when the rotation speed of the motor 6 at the same time is 2,000 rpm or less, and reduces the rotation speed of the motor 6 (for example, stops the motor 6).

FIG. 7 is a control flowchart of the electric working machine according to Embodiment 2. FIG. In the following, differences from the flowchart of the first embodiment shown in FIG. 4 will be mainly described. If the number of rotations of the motor 6 is not 1,800 rpm or more when 30 ms have passed since the start of driving the motor 6 (No in S5), the microcomputer 45 determines that the ambient temperature of the motor 6 is low, and drives the motor 6. When 90ms, which is the third predetermined time, has passed since the start (S21), it is checked whether the rotation speed of the motor 6 is 2,000 rpm or less, which is the third rotation speed (S23). If the number of rotations of the motor 6 is 2,000 rpm or less (Yes in S23), the microcomputer 45 determines that the tip tool 19 has caused a kickback in which the main body is swung, and stops the motor 6 (S25). If the number of rotations of the motor 6 is not 2,000 rpm or less when 90 ms have passed since the start of driving the motor 6 (No in S23), the microcomputer 45 determines that kickback has not occurred, and turns off the trigger switch 7. The driving of the motor 6 is continued unless it becomes (No of S13), and when the trigger switch 7 is turned off (Yes of S13), the motor 6 is stopped (S15).

Other points of this embodiment are the same as those of the first embodiment. According to the present embodiment, in addition to the effects of the first embodiment, kickback control (control to reduce the rotation speed of the motor 6 when kickback occurs) can be performed even when the ambient temperature of the motor 6 is low. Here, when the ambient temperature of the motor 6 is low, the third rotation speed, which is the threshold for determining the presence or absence of kickback, is set to False detection of kickback can be suppressed by setting it to 2,000 rpm, which is lower than . Although the second predetermined time and the third predetermined time are set to the same 90 ms in the present embodiment, they may be set to different times.

(Embodiment 3) The mechanical configuration and circuit configuration of the electric working machine of the present embodiment are common to the electric working machine 1 of Embodiment 1 shown in Figs. 1 to 3 . In the electric working machine of the present embodiment, unlike the electric working machine 1 of the first embodiment, when the ambient temperature of the motor 6 is low, the effective value of the voltage to be applied to the motor 6 is lower than when it is normal temperature. gradually increase toward the target value. Specifically, when the microcomputer 45 determines that the ambient temperature of the motor 6 is low from the number of rotations of the motor 6 or the output signal of the temperature detection element 48 when 30 ms has passed since the start of driving the motor 6, the inverter The duty of the PWM signal applied to the switching elements Q1 to Q6 of the circuit 35 (hereinafter also simply referred to as "duty") is gently increased toward the target value compared to when the ambient temperature of the motor 6 is normal temperature. As a result, when the ambient temperature of the motor 6 is low, the rotation speed of the motor 6 gradually increases toward the target rotation speed compared to when the ambient temperature of the motor 6 is normal temperature.

When the ambient temperature of the motor 6 is low, the viscosity of the lubricant is high. Therefore, if the duty is increased as in the case of normal temperature, the load applied to the motor 6 is increased. As a result, there is a risk that the overload protection function will operate and the motor 6 will stop, or that the peak current at the start of the motor 6 will increase and the electrical parts will break down. In this regard, in the present embodiment, when the ambient temperature of the motor 6 is low, the duty is increased more moderately than when it is normal temperature. It is possible to suppress the decrease in sexuality. In addition, it is possible to suppress the occurrence of defective impact due to the low temperature of the working environment.

Although the present invention has been described above with reference to the embodiments, it will be understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiments within the scope of the claims. By the way. Modifications will be discussed below.

The kickback control described in Embodiments 1 and 2 can be applied to other types of electric working machines besides hammer drills in which the housing is swung around by the driving of the tip tool and thus kickback can occur. Further, the control for gently increasing the duty when the ambient temperature of the motor 6 is low compared to when the ambient temperature is normal, as described in the third embodiment, can also be applied to an electric working machine in which kickback does not occur. In addition, specific values such as the number of rotations of the motor 6 and the elapsed time from the start of driving of the motor 6 exemplified in the embodiment can be appropriately changed by design.

DESCRIPTION OF SYMBOLS 1... Electric working machine (hammer drill), 2... Housing, 2a... Motor accommodating part, 2b... Handle part, 3... Gear case, 4... Side handle, 5... Tip tool holding part, 6... Motor, 7... Trigger switch, 8 Operation panel 9 Gear 10 Gear 11 Intermediate shaft 12 First clutch member 13 Second clutch member 14 Gear 15 Piston 16 Air chamber 17 Striker ), 18 Second hammer (meson) 19 Tip tool 20 Slip clutch mechanism (clutch portion) 21 Filter board 22 Control board 23 Fan 24 Magnet 25 Inverter board 26 Reciprocating bearing (reciprocating motion conversion mechanism) 27 Power cord 28 Cylinder 29 AC/DC conversion circuit board 31 AC power supply 32 Filter circuit 33 AC/DC conversion circuit 34 Control circuit voltage Supply circuit 35 Inverter circuit 40 Control circuit 41 Motor current detection circuit 42 Step-down circuit 43 Control signal output circuit 44 Hall IC signal detection circuit 45 Microcomputer (control unit) 47 ... hall IC, 48 ... temperature detection element

Claims (7)

a motor;
a control unit that controls driving of the motor;
A rotation speed detection unit that detects the rotation speed of the motor,
The control unit performs a first start-up control when a low temperature determination condition indicating that the ambient temperature of the motor is low is not satisfied in the start control for increasing the rotation speed of the motor , and the low temperature determination condition is satisfied. If it is, perform the second startup control,
The control unit
In the first startup control, when a first predetermined condition is satisfied, the rotation speed of the motor is reduced,
In the second startup control, even if the first predetermined condition is satisfied, the number of revolutions of the motor is not reduced,
The electric working machine, wherein the first predetermined condition includes that the number of rotations of the motor is less than a predetermined number of rotations when a predetermined time has elapsed since the start of driving of the motor. The electric working machine according to claim 1, wherein the low temperature determination condition includes that the number of rotations of the motor is less than the first number of rotations when a first predetermined time has passed since the start of driving of the motor. A temperature detection means for detecting the ambient temperature,
2. The electric working machine according to claim 1, wherein said low temperature determination condition includes a condition regarding a detection value of said temperature detection means. a housing that accommodates the motor and the controller;
a tip tool operated by the driving force of the motor,
The electric working machine according to any one of claims 1 to 3, wherein the control unit determines that the housing has been swung by the operation of the tip tool when the first predetermined condition is satisfied. 5. The electric working machine according to claim 4, further comprising a clutch section that disconnects a transmission path for transmitting the driving force of the motor to the tool bit when the load applied to the tool bit is equal to or greater than a predetermined value. In the second startup control, the control unit reduces the rotation speed of the motor when a second predetermined condition is satisfied ,
The predetermined time is a second predetermined time,
The predetermined number of rotations is a second number of rotations,
The first predetermined condition includes that the number of rotations of the motor is less than the second number of rotations when a third predetermined time has elapsed from the start of driving of the motor,
3. The second predetermined condition includes that the number of rotations of the motor when the third predetermined time has elapsed from the start of driving of the motor is less than a third number of rotations, which is lower than the second number of rotations. 6. The electric working machine according to any one of 1 to 5 . 4. The electric motor according to any one of claims 1 to 3, wherein in the second startup control, the control unit gently increases an effective value of the voltage applied to the motor as compared with the first startup control. work machine

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