A power tool

Abstract

The application provides an electric tool. The electric tool comprises a housing, a driving part arranged on the housing and located on one side of the housing, a fixing part connected to the housing and located on the side of the housing away from the driving part, the fixing part being used for fixing a working piece, and a detection device arranged on the housing, located between the driving part and the fixing part, and connected to the driving part at one end and to the working piece at the other end, wherein the detection device is capable of detecting the output torque of the electric tool. The application can solve the technical problem that the output torque accuracy of the electric tool is difficult to control when the output torque is output.

Description

Technical Field

[0001] This invention relates to the field of power tool technology, and more specifically, to a power tool. Background Technology

[0002] With the development of power tools, more and more power tools are capable of adjusting torque to regulate the output speed. In related technologies, the torque adjustment structure of power tools is located at the output end and requires manual adjustment by the operator. The torque level is adjusted by gradually rotating the adjustment structure. However, the torque adjustment method in these technologies is relatively complex, making it difficult to control the output torque accuracy during actual adjustment. Summary of the Invention

[0003] This invention can solve the technical problem that it is difficult to control the accuracy of output torque when power tools are outputting torque.

[0004] To address the aforementioned problems, this invention provides an electric tool comprising: a housing; a drive unit disposed on one side of the housing; a fixing unit connected to the housing and located on the side of the housing away from the drive unit, the fixing unit being used to fix a workpiece; and a detection device disposed on the housing between the drive unit and the fixing unit, one end of the detection device being connected to the drive unit and the other end being connected to the workpiece; wherein the detection device is capable of detecting the output torque of the electric tool.

[0005] Compared with the prior art, the beneficial effects of this embodiment are as follows: by setting a detection device between the drive unit and the fixed unit, the output torque of the power tool can be detected; since the drive unit can ultimately drive the workpiece to move, and the detection device is set between the two, the running status of the drive unit and the workpiece can be detected in real time, thereby determining the real-time output torque of the power tool and feeding the torque back to the user. Finally, the output torque of the power tool can be precisely adjusted by adjusting the gear of the drive motor, thereby overcoming the problem of difficult control of the output torque accuracy of power tools in the prior art, and further improving the efficiency of power tool use.

[0006] Furthermore, in this invention, the detection device includes: an output shaft connected between the driving part and the fixed part; a first adjusting member sleeved on the output shaft and located on the side of the output shaft near the fixed part; and a second adjusting member sleeved on the output shaft and located on the side of the output shaft near the driving part; wherein there is a gap between the second adjusting member and the first adjusting member.

[0007] Compared with the prior art, the beneficial effects of this embodiment are as follows: by setting the first and second adjusting members, the magnitude of the output torque can be fed back to the user. It is understood that during the operation of the electric drill, both the output shaft and the drill bit will vibrate. At the same time, there is a gap between the first and second adjusting members. Therefore, the first and second adjusting members, which are sleeved on the outside of the output shaft, will also move under this influence. Especially when the motor speed is higher, the movement is more obvious, which can ultimately remind the user to adjust the output torque. The setting of the first and second adjusting members improves the detection efficiency of the output torque of the power tool.

[0008] Furthermore, in this invention, the detection device further includes an elastic element disposed within the interval, with one end of the elastic element connected to a first adjusting element and the other end connected to a second adjusting element.

[0009] Compared with the prior art, the beneficial effects of this embodiment are as follows: by setting an elastic element, accurate detection of output torque can be achieved. It can be understood that since the elastic element is set between the first adjusting element and the second adjusting element, the elastic element deforms during the relative movement of the first adjusting element and the second adjusting element, and the output torque of the power tool is changed accordingly. Therefore, by controlling the magnitude of the deformation of the elastic element, accurate detection of output torque can be achieved, thereby ensuring the efficiency of the power tool.

[0010] Furthermore, in this invention, the detection device further includes: a sensor, which is disposed on the first adjusting member or the second adjusting member; wherein the sensor is used to detect the size of the interval, or the sensor is used to detect the size of the elastic member.

[0011] Compared with the prior art, the beneficial effects of this embodiment are as follows: setting up a sensor can detect the deformation of the elastic element, and by detecting the magnitude of the deformation of the elastic element, feedback is given to the user, ultimately achieving the purpose of accurately adjusting the output torque of the power tool.

[0012] Furthermore, in this invention, the output shaft includes: a connecting end located on the side of the output shaft near the driving part, for connecting the driving part; an output end located on the side of the output shaft near the fixing part; and a workpiece mounting position located at the output end for mounting the workpiece.

[0013] Compared with the prior art, the beneficial effects of this embodiment are as follows: the connection end and the output end realize the transmission between the drive unit and the drill bit. At the same time, since the first adjustment member and the second adjustment member are set on the output shaft, the output torque of the output shaft can be fed back to the user through the movement of the first adjustment member and the second adjustment member during the operation of the output shaft and the working part, and finally remind the user to make torque adjustment, thereby improving the efficiency of the power tool and also increasing the service life of the power tool.

[0014] Furthermore, in this invention, the detection device further includes a limiting member, which is disposed on the output shaft and located between the first adjusting member and the fixed part, for limiting the movement of the first adjusting member toward the fixed part.

[0015] Compared with the prior art, the beneficial effects of this embodiment are as follows: the setting of the limiting member limits the position of the first adjusting member, preventing the first adjusting member from slipping off the output shaft during the operation of the power tool, thereby improving the efficiency of the power tool.

[0016] Furthermore, in this invention, the driving unit includes: a drive motor with a motor shaft; a gearbox, one end of which is connected to the motor shaft and the other end of which is connected to the detection device; wherein, when the drive motor rotates, the motor shaft can drive the detection device to move through the gearbox.

[0017] Compared with the prior art, the beneficial effects of this embodiment are as follows: the gearbox enables the linkage between the drive motor, the detection device, and the workpiece, ensuring that the power tool can be used normally and improving efficiency.

[0018] Furthermore, in this invention, a planetary gear structure is provided inside the gearbox, and the drive motor and the detection device are transmitted through the planetary gear structure.

[0019] Compared with the prior art, the beneficial effects of adopting this embodiment are: the planetary gear configuration improves transmission efficiency and increases the efficiency of power tool use.

[0020] Furthermore, in this invention, the drive unit further includes a gear adjustment member, which is disposed on the side of the housing near the drive unit and electrically connected to the drive unit for adjusting the gear of the drive motor.

[0021] Compared with the prior art, the beneficial effects of this embodiment are as follows: the setting of the gear adjustment component realizes the adjustment of the gear of the drive motor, and ultimately achieves the adjustment of the output torque of the workpiece, thereby ensuring the efficiency of the power tool.

[0022] Furthermore, the present invention also includes: a handheld part, which is connected to the housing and located on the side of the housing near the drive part; and a start switch, which is disposed on the handheld part and electrically connected to the drive part for controlling the start and stop of the drive part.

[0023] In summary, by adopting the technical solution of the present invention, the following technical effects can be achieved:

[0024] i) By setting a detection device between the drive unit and the fixed unit, the output torque of the power tool can be detected. Since the drive unit can ultimately drive the workpiece to move, and the detection device is set between the two, the running status of the drive unit and the workpiece can be detected in real time, thereby determining the real-time output torque of the power tool and feeding the torque back to the user. Finally, the output torque of the power tool can be precisely adjusted by adjusting the gear of the drive motor. This overcomes the problem of difficult control of the output torque accuracy of power tools in the prior art and further improves the efficiency of power tool use.

[0025] ii) By setting the first and second adjustment components, the output torque can be fed back to the user. It is understood that during the operation of the electric drill, both the output shaft and the drill bit will vibrate. At the same time, there is a gap between the first and second adjustment components. Therefore, the first and second adjustment components, which are sleeved on the outside of the output shaft, will also move under this influence. Especially when the motor speed is higher, the movement is more obvious. Finally, it can remind the user to adjust the output torque. The setting of the first and second adjustment components improves the detection efficiency of the power tool output torque.

[0026] iii) By setting up an elastic element, the output torque can be accurately detected. It can be understood that since the elastic element is set between the first and second adjusting elements, the elastic element deforms during the relative movement of the first and second adjusting elements, which ultimately changes the output torque of the power tool accordingly. Therefore, by controlling the magnitude of the deformation of the elastic element, the output torque can be accurately detected, thereby ensuring the efficiency of the power tool. Attached image description:

[0027] Figure 1 This is a schematic diagram of the structure of the power tool provided in the first embodiment of the present invention.

[0028] Figure 2 for Figure 1 A schematic diagram of the internal structure of the middle shell.

[0029] Figure 3 for Figure 2 A schematic diagram of the detection device.

[0030] Figure 4 for Figure 3 A schematic diagram of the internal structure of the detection device.

[0031] Figure 5 for Figure 3 The front view.

[0032] Figure 6 for Figure 5 A cross-sectional view along the AA direction.

[0033] Figure 7 for Figure 1 Top view.

[0034] Figure 8 for Figure 7 A cross-sectional view along the BB direction.

[0035] Figure 9 for Figure 8 The center circle shows a magnified view of part C.

[0036] Figure 10 This is a schematic diagram of the detection device provided in the second embodiment of the present invention.

[0037] Explanation of reference numerals in the attached figures:

[0038] 100 - Power tool; 10 - Housing; 11 - First housing; 12 - Second housing; 13 - Handheld part; 20 - Drive unit; 21 - Drive motor; 211 - Motor shaft; 212 - Motor drive protection plate; 22 - Gearbox; 221 - Gear; 222 - Planetary gear; 40 - Detection device; 41 - First adjusting component; 411 - First mounting hole; 42 - Second adjusting component; 43 - Sensor; 44 - Elastic component; 50 - Fixing part; 60 - Gear adjustment component; 70 - Start switch; 80 - Output shaft; 801 - Output end; 802 - Connection end; 803 - Working part mounting position; 804 - Limiting component. Detailed Implementation

[0039] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the description of the present invention, it should be understood that the terms "lateral," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0040] See Figure 1 The first embodiment of the present invention provides an electric tool 100, the output torque of which is adjustable. By precisely adjusting the output torque of the electric tool 100, the efficiency of the electric tool 100 is improved. The electric tool 100 can be an electric drill, a reciprocating saw, a polishing machine, etc. It should be noted that in the present invention, the electric tool 100 is an electric drill.

[0041] Preferred, see Figure 1 and Figure 2 The power tool 100 includes a housing 10, a drive unit 20, a fixing unit 50, and a detection device 40. The drive unit 20 is disposed on the housing 10 and located on one side of the housing 10. The fixing unit 50 is connected to the housing 10 and located on the side of the housing 10 away from the drive unit 20, and is used to fix the workpiece. The detection device 40 is disposed on the housing 10, located between the drive unit 20 and the fixing unit 50, and one end of the detection device 40 is connected to the drive unit 20, and the other end is connected to the workpiece. The drive unit 20 can drive the detection device 40 to move, thereby adjusting the output torque of the workpiece through the detection device 40. In this process, accurate detection of the output torque of the power tool 100 is achieved, and the efficiency of the power tool is improved.

[0042] Specifically, when the power tool 100 is an electric drill, the working part is the drill bit (not shown in the figure). At this time, the first end of the drill bit is connected to the detection device 40, and the second end extends away from the detection device 40. The fixing part 50 is sleeved on the outside of the first end of the drill bit, and after the drill bit is connected to the detection device 40, it is fixed by the fixing part 50. By setting the detection device 40 between the drive part 20 and the fixing part 50, the output torque of the power tool 100 is detected, thereby determining the real-time output torque of the power tool 100 and feeding the torque back to the user. Finally, the output torque of the power tool 100 is precisely adjusted by adjusting the power tool 100. The above method achieves precise control of the output torque of the power tool 100, thereby overcoming the problem of difficult control of the output torque accuracy of the power tool 100 in the prior art, further improving the efficiency of the power tool 100 and ensuring the service life of the power tool 100.

[0043] Furthermore, the power tool 100 also includes a handheld part 13 and a start switch 70; wherein, the handheld part 13 is connected to the housing 10 and is located on the side of the housing 10 near the drive unit 20, for taking the power tool 100 out; the start switch 70 is disposed on the handheld part 13 and electrically connected to the drive unit 20, for controlling the start and stop of the drive unit 20.

[0044] Preferably, the drive unit 20 includes a drive motor 21, a gearbox 22, and a gear adjustment component 60. The drive motor 21 is provided with a motor shaft 211. One end of the gearbox 22 is connected to the motor shaft 211, and the other end is connected to the detection device 40. When the drive motor 21 rotates, the motor shaft 211 can drive the working part to move through the gearbox 22. The detection device 40 can detect the movement of the gearbox 22 and the working part in real time. The gear adjustment component 60 is provided on the side of the housing 10 near the drive unit 20 and is electrically connected to the drive unit 20 for adjusting the gear of the drive motor 21. The fixing part 50 and the gear adjustment component 60 are located on both sides of the housing 10.

[0045] Furthermore, the housing 10 includes: a first housing 11 and a second housing 12; the first housing 11 is connected to the second housing 12, and after the first housing 11 is connected to the second housing 12, the drive unit 20 and the detection device 40 are disposed inside the first housing 11 and the second housing 12, the fixing part 50 is located on the side closer to the first housing 11, and the gear adjustment member 60 is located on the side closer to the second housing 12.

[0046] Preferred, see Figures 3-6 The detection device 40 includes: an output shaft 80, a first adjusting member 41, a second adjusting member 42, and an elastic member 44; the output shaft 80 is connected between the driving part 20 and the fixed part 50; the first adjusting member 41 is sleeved on the output shaft 80 and located on the side of the output shaft 80 near the fixed part 50; the second adjusting member 42 is sleeved on the output shaft 80 and located on the side of the output shaft 80 near the driving part 20; wherein, there is a gap between the second adjusting member 42 and the first adjusting member 41; the elastic member 44 is disposed within the gap, and one end of the elastic member 44 is connected to the first adjusting member 41, and the other end is connected to the second adjusting member 42; the first adjusting member 41 and the second adjusting member 42 are connected to the first adjusting member 41 and the second adjusting member 42, respectively ... The two adjusting members 42 can move relative to each other. It is understood that during the operation of the electric drill, the output shaft 80 and the drill bit will vibrate. Therefore, the first adjusting member 41 and the second adjusting member 42, which are sleeved outside the output shaft 80, will also move under this influence. The movement is more obvious when the motor speed is higher. Furthermore, during the relative movement of the first adjusting member 41 and the second adjusting member 42, the elastic member 44 is deformed, which affects the size of the gap between the first adjusting member 41 and the second adjusting member 42, and ultimately changes the output torque of the power tool 100 accordingly.

[0047] Furthermore, the elastic element 44 can be made of other elastic materials such as springs and elastic washers. When the elastic element 44 is a spring, a first mounting hole 411 and a second fixing hole (not shown in the figure) for fixing the spring are respectively provided on the first adjusting member 41 and the second adjusting member 42. The two ends of the spring are fixed between the first adjusting member 41 and the second adjusting member 42 through the first mounting hole 411 and the second fixing hole, respectively. At the same time, in order to further ensure the precise adjustment of the distance between the first adjusting member 41 and the second adjusting member 42, multiple springs can be provided, and multiple springs are spaced apart between the first adjusting member 41 and the second adjusting member 42.

[0048] It should be noted that when adjusting the output torque of the power tool 100, the deformation of the elastic element 44 will vary, resulting in different output torques. Therefore, by detecting the deformation of the elastic element 44 in real time, precise control of the output torque of the power tool 100 can be achieved. Even when the power tool current is low, the user can receive real-time feedback by detecting the deformation of the elastic element 44, thereby adjusting the gear of the power tool 100 and ultimately achieving the purpose of adjusting the output torque.

[0049] Specifically, the detection device 40 further includes: a sensor 43; the sensor 43 is disposed on the first adjusting member 41 or on the second adjusting member 42; the sensor 43 is used to detect the size of the gap between the first adjusting member 41 and the second adjusting member 42, or the sensor 43 is used to detect the size of the elastic member 44.

[0050] It should be noted that, in this embodiment of the invention, the essence of detecting the deformation of the elastic element 44 is still to detect the change in distance between the first adjusting element 41 and the second adjusting element 42. The addition of the elastic element 44 improves the accuracy of torque detection. Therefore, if the change in the output torque of the power tool 100 is small, the elastic element 44 can be omitted. In this case, a sensor can be used to directly detect the distance between the first adjusting element 41 and the second adjusting element 42. Alternatively, the first adjusting element 41 and the second adjusting element 42 can be sleeved on the output shaft 80, and after connecting the first adjusting element 41 and the second adjusting element 42, the sensor can directly detect the change in the size of the gap between the first adjusting element 41 and the second adjusting element 42. This also achieves the control of the output torque of the power tool 100. Of course, other methods can also be used, as long as the adjustment of the output torque of the power tool 100 can be achieved. It is not limited to the method of setting the elastic element and the sensor in this embodiment, and will not be elaborated here.

[0051] Preferably, in this embodiment of the invention, the purpose of setting the sensor is to detect the deformation of the elastic element 44. Therefore, when setting the sensor, in addition to setting the sensor between the first adjusting member 41 and the second adjusting member 42, the sensor can also be set at any position. For example, the sensor can be set at the position of the housing 10 close to the detection device 40. At this time, the sensor can detect the change in distance between the first adjusting member 41 and the second adjusting member 42, that is, detect the magnitude of the deformation of the elastic element 44, so that the user can understand the magnitude of the output torque of the power tool 100 in real time and finally adjust it.

[0052] Preferably, an electronic torque adjustment control board (not shown in the figure) is provided on the drive unit 20. When the user needs to output a certain torque, the specific torque value can be transmitted to the drive motor through the electronic torque adjustment control board. Furthermore, the torque value detected by the sensor can be transmitted to the motor drive protection board 212 to determine whether the gear of the drive motor 21 needs to be adjusted. At the same time, it can also control the operation and pause of the drive motor 21.

[0053] Preferably, the output shaft 80 is provided with an output end 801, a connecting end 802, and a workpiece mounting position 803. The connecting end is located on the side of the output shaft 80 near the drive unit 20 and is used to connect to the drive unit 20. The connecting end is located on the side of the output shaft 80 near the fixing unit 50. The workpiece mounting position 803 is provided on the output end 801 and is used to mount the workpiece, i.e., to mount the electric drill bit.

[0054] Furthermore, the detection device 40 also includes a limiting member 804; the limiting member 804 is disposed on the outside of the output shaft 80 and located between the first adjusting member 41 and the fixing part 50, for limiting the movement of the first adjusting member 41 toward the fixing part 50, so as to prevent the first adjusting member 41 from falling off the output shaft 80.

[0055] Preferred, see Figures 7-9 The gearbox 22 is equipped with a planetary gear structure, which can cooperate with the motor shaft 211. Specifically, the planetary gear structure is equipped with multiple planetary gears 222, and a gear 221 is provided at the end of the motor shaft 211. The end of the gear 221 can mesh with the multiple planetary gears 222, so that when the motor shaft 211 rotates, it can drive the multiple planetary gears 222 to rotate. Finally, when the multiple planetary gears 222 rotate, they drive the output shaft 80 and the drill bit to rotate.

[0056] See Figure 10Based on the first embodiment, the second embodiment of the present invention provides another structure for the detection device 40. Specifically, the detection device 40 includes: a first adjusting member 41, an elastic member 44, and a sensor 43; wherein the first adjusting member 41 and the elastic member 44 are both sleeved outside the output shaft 80, and the elastic member 44 is sandwiched between the first adjusting member 41 and the gearbox 22; the sensor 43 is disposed on the elastic member 44 and is used to detect the deformation of the elastic member 44. Of course, the sensor 43 can also be disposed in other positions, as long as it can detect the deformation of the elastic member 44, and is not limited to the placement position in the present invention.

[0057] It should be noted that in this embodiment, the elastic element 44 is set in a ring shape, and after the elastic element 44 is sandwiched between the first adjusting element 41 and the gearbox 22, both sides of the elastic element 44 are respectively in contact with the first adjusting element 41 and the gearbox 22. It can be understood that during the operation of the drive motor 21, the drive motor 21 vibrates, which in turn drives the gearbox 22 and the output shaft 80 to vibrate. Since the elastic element 44 is in contact with the gearbox 22, the gearbox 22 will squeeze the elastic element 44 during the vibration, which will cause the elastic element 44 to deform. At this time, the sensor 43 set on the elastic element 44 can detect the magnitude of the deformation of the elastic element 44 in real time, and then reflect the magnitude of the output torque of the output shaft 80 through the magnitude of the deformation, and give real-time feedback to the user, thereby adjusting the gear of the power tool 100, and finally achieving the purpose of adjusting the output torque. In this embodiment, by changing the number of adjusting plates and directly detecting the deformation of the elastic element 44, the purpose of accurately detecting the output torque of the power tool 100 is also achieved.

[0058] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A power tool, characterized in that, include: Shell (10); A drive unit (20) is disposed on the housing (10) and located on one side of the housing (10); A fixing part (50) is connected to the housing (10) and located on the side of the housing (10) away from the driving part (20). The fixing part (50) is used to fix the working part. A detection device (40) is disposed in the housing (10), located between the driving part (20) and the fixing part (50), and one end of the detection device (40) is connected to the driving part (20), and the other end is connected to the working part; The detection device (40) is capable of detecting the output torque of the power tool (100); The detection device (40) includes: An output shaft (80) is connected between the drive unit (20) and the fixed unit (50); The first adjusting member (41) is sleeved on the output shaft (80) and located on the side of the output shaft (80) near the fixing part (50); The second adjusting member (42) is sleeved on the output shaft (80) and located on the side of the output shaft (80) near the drive unit (20); there is a gap between the second adjusting member (42) and the first adjusting member (41); An elastic element (44) is disposed within the interval, and one end of the elastic element (44) is connected to the first adjusting element (41) and the other end is connected to the second adjusting element (42). Sensor (43), the sensor (43) is disposed on the first adjusting member (41) or on the second adjusting member (42); The sensor (43) is used to detect the size of the interval. The first adjusting member (41) and the second adjusting member (42) can move relative to each other. During the operation of the electric drill, the output shaft (80) and the drill bit will vibrate. Therefore, the first adjusting member (41) and the second adjusting member (42) sleeved outside the output shaft (80) will also move under this influence. During the relative movement of the first adjusting member (41) and the second adjusting member (42), the elastic member (44) will deform, affecting the size of the interval between the first adjusting member (41) and the second adjusting member (42), and finally changing the output torque of the power tool (100). By detecting the deformation of the elastic member (44) in real time, real-time feedback is given to the user, and the gear of the power tool (100) is adjusted, so as to achieve the purpose of adjusting the output torque.

2. The power tool according to claim 1, characterized in that, The output shaft (80) includes: Connection end (802), the connection end is located on the side of the output shaft (80) near the drive unit (20), and is used to connect the drive unit (20). Output end (801), the connection end is located on the side of the output shaft (80) near the fixing part (50); The workpiece mounting position (803) is located at the output end (801) and is used to mount the workpiece.

3. The power tool according to claim 1, characterized in that, The detection device (40) further includes: A limiting member (804) is disposed on the output shaft (80) and located between the first adjusting member (41) and the fixed part (50), for limiting the movement of the first adjusting member (41) toward the fixed part (50).

4. The power tool according to claim 1, characterized in that, The drive unit (20) includes: A drive motor (21) is provided with a motor shaft (211). A gearbox (22), one end of which is driven to the motor shaft (211) and the other end is driven to the detection device (40); When the drive motor (21) rotates, the motor shaft (211) can drive the detection device (40) to move through the gearbox (22).

5. The power tool according to claim 4, characterized in that, The gearbox (22) is equipped with a planetary gear structure, and the drive motor (21) and the detection device (40) are transmitted through the planetary gear structure.

6. The power tool according to claim 4, characterized in that, The drive unit (20) also includes: A gear adjustment component (60) is disposed on the side of the housing near the drive unit (20) and electrically connected to the drive unit (20) for adjusting the gear of the drive motor (21).

7. The power tool according to any one of claims 1-6, characterized in that, Also includes: Handheld part (13), the handheld part (13) is connected to the housing and is located on the side of the housing (10) near the drive part (20); A start switch (70) is provided on the handheld part (13) and electrically connected to the drive part (20) for controlling the start and stop of the drive part (20).

Images