Power tool and control method

Abstract

The application discloses an electric tool, which comprises a head shell, a motor, a switch module and a control module. The control module detects the operation amount of the switch module. The control module stores the drive duty ratio corresponding to the operation amount. The control module controls the corresponding drive duty ratio to drive the motor to operate according to the operation amount. The motor comprises a first running stage and a second running stage. When the switch module is closed, the motor is in the first running stage. When the control module detects that the operation amount of the switch module is greater than or equal to a first threshold value and lasts for a predetermined time, the control module controls the motor to switch to the second running stage. The first threshold value and the predetermined time are stored in the control module in advance. The application divides the motor operation into stages. The user can set the short-circuit protection value in different stages, which meets the requirement that the electric tool needs large current when starting and needs relatively small short-circuit protection value when working normally.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electric tools, in particular to an electric tool and a control method. BACKGROUND

[0002] With the wide application of electric tools, electric wrenches gradually replace traditional manual wrenches, and electric ratchet wrenches become the first choice of users when tightening bolts due to their large locking force. Electric ratchet wrenchs are different from conventional electric wrenches, and they realize transmission by ratchet structure. When tightening the bolt, the power of motor blockage is completely relied on to complete the bolt tightening. At the moment of tightening the bolt, the current changes suddenly, and each completion of bolt tightening is equivalent to one time of motor blockage. In the case of pursuing the locking force of the bolt, the greater the protection current of the motor blockage is, the greater the locking force of the bolt is. At the same time, the problem is that the greater the current of the motor blockage is, the MOS tube needs to withstand about 110A of instantaneous current impact, which is easy to burn out. At the same time, the transmission structure of the machine head also reduces the service life, so it is necessary to reduce the short-circuit protection value of the electric ratchet wrench to 53A, while meeting the requirement of fast starting of the electric ratchet wrench. The current peak at the start is easy to exceed 53A, triggering the short-circuit protection.

[0003] Please refer to the Chinese invention patent No. CN109986154B announced on December 1, 2020, which discloses a kind of multi-station blade electrolytic machining intelligent control pulse power system and control method, the system includes short-circuit protection circuit, and the short-circuit protection circuit uses maximum current limiting method, gives a preset current value, if current exceeds preset value in processing process, then circuit protection measures will be taken. However, this control method can only realize short-circuit protection when the current in the circuit is too large, and cannot meet the condition of large current required by the ratchet wrench when completing bolt tightening.

[0004] Therefore, it is necessary to provide an improved electric tool and control method to overcome the defects in the prior art. SUMMARY

[0005] In view of the shortcomings of the prior art, the purpose of the present application is to provide a control method that can be applied to the condition of requiring large current at start and relatively small blockage protection and short-circuit protection value at normal work.

[0006] The technical solution adopted by the present invention to solve the existing technical problems is: an electric tool, including a head shell, a motor located in the head shell, a switch module connected to the motor and a control module, the control module detects the operation amount of the switch module, the control module stores a drive duty cycle corresponding to the operation amount, and the control module controls the output of the corresponding drive duty cycle according to the operation amount to drive the motor to operate; the control module stores a first threshold, a second threshold, a third threshold and a predetermined time, and the second threshold is greater than the third threshold; the motor includes a first operating stage and a second operating stage, and the first operating stage and the second operating stage are respectively set with different short-circuit protection values. When the switch module is closed, the motor is in the first operating stage, and the control module sets the short-circuit protection value to the second threshold. When the control module detects that the operation amount of the switch module is greater than or equal to the first threshold and lasts for a predetermined time, it controls the motor to switch to the second operating stage, and the control module sets the short-circuit protection value to the third threshold.

[0007] A further improvement is that the second threshold is the maximum current value of the motor in the first operating stage. , the third threshold is the maximum current value of the motor in the second operating stage , and the second threshold Greater than the third threshold .

[0008] A further improvement is: the second threshold is the initial value of the short-circuit protection value, that is, when the power tool starts working, the control module controls and sets the short-circuit protection value to .

[0009] A further improvement is as follows: the first operating stage is the soft start stage of the electric tool, and the second operating stage is the normal operating stage of the electric tool.

[0010] The present invention can also adopt the following technical solution to solve the existing technical problems: a power tool control method, the control method comprising:

[0011] The control module detects the closed state of the switch module;

[0012] The control module determines the working state of the motor according to the closed state;

[0013] When the working state indicates that the motor is in the first operating state, setting the short-circuit protection value to a second threshold value, and obtaining the operation amount of the switch module;

[0014] When the operation amount of the switch module is greater than or equal to a first threshold, obtaining a duration of time in which the switch module is in the operation amount;

[0015] When the duration reaches a predetermined time length, the motor switches to the second operation stage, and sets the short-circuit protection value to a third threshold.

[0016] A further improvement is that the second threshold is the maximum current value of the motor in the first operating stage. , the third threshold is the maximum current value of the motor in the second operating stage , and the second threshold Greater than the third threshold .

[0017] . A further improvement is: the second threshold is the initial value of the short-circuit protection value, that is, when the power tool starts working, the control module controls and sets the short-circuit protection value to .

[0018] A further improvement is as follows: the first operating stage is the soft start stage of the electric tool, and the second operating stage is the normal operating stage of the electric tool.

[0019] Compared to existing technologies, the present invention offers the following advantages: When the switch module is closed and the motor is in the first operating stage, the control module controls the motor to switch to the second operating stage when it detects that the amount of operation of the switch module is greater than or equal to a first threshold and persists for a predetermined period of time. By dividing motor operation into stages, users can set short-circuit protection values ​​for different stages, thus meeting the requirements of power tools that require high current during startup but relatively low stall protection and short-circuit protection values ​​during normal operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings:

[0021] Figure 1 is a front view of the power tool of the present invention;

[0022] Figure 2 is a cross-sectional view of the power tool of the present invention;

[0023] Figure 3 is a front view of the head shell of the power tool of the present invention;

[0024] Figure 4 is a cross-sectional view of the head shell of the power tool of the present invention;

[0025] Figure 5 is a circuit diagram of the electric tool of the present invention;

[0026] Figure 6 It is a principle flow chart of the electric tool of the present invention;

[0027] Figure 7 is a current diagram of the power tool of the present invention; DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0029] The terminology used in this disclosure is for the purpose of describing specific embodiments only and is not intended to limit the disclosure. Terms such as "upper," "lower," "front," and "rear" that indicate orientation or positional relationships are based solely on the orientations or positional relationships shown in the accompanying drawings. These terms are used solely to facilitate description and simplify the description of the disclosure and are not intended to indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the disclosure.

[0030] See also Figure 1 1 is a main view of the power tool of the present invention. In the present invention, the power tool is a ratchet wrench. The ratchet wrench 100 includes a head shell 101 and a shell 102 extending longitudinally. The shell 102 includes a main body 1021 covering the rear end of the head shell 101 and a gripping portion 1022 located at the rear end of the main body 1021. The gripping portion 1022 is used for a user to grip.

[0031] See also Figure 2 FIG. 1 is a cross-sectional view of the power tool of the present invention. The ratchet wrench 100 further includes a motor 103 and a battery 200 located within the housing 102. A control module 104 is disposed between the motor 103 and the battery 200. Specifically, the battery 200 is inserted from the longitudinal rear end of the housing 102 and partially located within the grip 1022, thereby powering the ratchet wrench 100. The ratchet wrench 100 further includes a switch module 105 connected to the control module 104. The switch module 105 is partially exposed outside the housing 102, allowing the user to control the start and stop of the ratchet wrench 100.

[0032] See also Figure 2 、 Figure 3 and Figure 4As shown in the sectional view of the electric tool and the front view and sectional view of the head shell, the ratchet wrench 100 further comprises a transmission module 106 connected to the motor 103, a drive module 107 driven by the transmission module 106, and a ratchet module 108 connected to the front end of the drive module 107, wherein the transmission module 106 is a planetary gear structure. The ratchet module 108 comprises a clutch fork 1081 at the front end of the drive module 107 and a ratchet assembly 1082 in the clutch fork 1081.

[0033] The drive module 107 comprises an output shaft 1071 connected to the transmission module 106 and an eccentric pin 1072 extending forward from the front end of the output shaft 1071. The output shaft 1071 is fixedly connected to the longitudinal front end of the transmission module 106 and is driven by the transmission module 106, the motor 103 drives the drive module 107 to rotate around the longitudinal direction through the transmission module 106, and the motor shaft (not shown) of the motor 103 has the same rotation axis as the output shaft 1071 of the drive module 107, the ratchet module 108 is connected to the front end of the drive module 107, and the rotation of the drive module 107 is converted into rotation around the vertical direction perpendicular to the longitudinal direction. The eccentric pin 1072 is offset from the center of the output shaft 1071 by a certain distance, and when the output shaft 1071 rotates around the longitudinal axis, the eccentric pin 1072 moves in a circular motion around the longitudinal axis.

[0034] Please participate Figures 5 to 7 As shown in the circuit schematic diagram, the principle flowchart and the current diagram of the electric tool, the ratchet wrench 100 further comprises a voltage detection module 109 for detecting the voltage of the battery 200, a current detection module 110 for detecting the current of the motor 103, and a power module 111, wherein the power module 111 is connected to the battery 200, and the battery 200 supplies power to the power module 111.

[0035] The switch module 105 is operated by the user, and the control module 104 detects the operation amount of the switch module 105. In this embodiment, the switch module 105 is a trigger, and the control module 104 detects the stroke amount of the trigger 105 being pressed. The control module 104 stores a drive duty ratio corresponding to the stroke amount, and the control module 104 controls the output of the corresponding drive duty ratio to drive the motor 103 to operate according to the stroke amount. The greater the stroke amount, the greater the drive duty ratio controlled by the control module 104, and the higher the speed of the motor 103.

[0036] The motor 103 comprises a first operating stage and a second operating stage. The trigger 105 is closed, and the motor 103 is in the first operating stage. When the control module 104 detects that the stroke amount of the trigger 105 is greater than or equal to a first threshold value and lasts for a predetermined time, the control module 104 controls the motor 103 to switch to the second operating stage. The first threshold value and the predetermined time are pre-stored in the control module 104. In this embodiment, the first operating stage is a soft start stage of the ratchet wrench 100, the second operating stage is a normal working stage of the ratchet wrench 100, the first threshold value is 50% of the stroke amount of the trigger, and the predetermined time is 50 ms.

[0037] The control module 104 further stores a second threshold value and / or a third threshold value. The second threshold value is a maximum current value of the motor 103 in the first operating stage , the third threshold value is a maximum current value of the motor 103 in the second operating stage , and the second threshold value is greater than the third threshold value . The second threshold value is an initial value of the short-circuit protection value, that is, when the ratchet wrench 100 starts to work, the control module 104 controls to set the short-circuit protection value to .

[0038] In this embodiment, the user pre-sets the second threshold value to 110 A, and the third threshold value to 53 A. The ratchet wrench 100 needs to be bolted in the soft start stage, and the instantaneous current of the motor 103 is very large. Therefore, when the ratchet wrench 100 starts to work, the short-circuit protection current value of the ratchet wrench 100 is set to 110 A, so as to prevent the working current of the motor 103 from being too large to damage the ratchet wrench 100. After the ratchet wrench 100 completes the bolt fastening, the ratchet wrench 100 is in the normal working stage, and the current of the motor 103 is far less than the instantaneous current. Therefore, in the normal working stage, the short-circuit protection current value of the ratchet wrench 100 is set to 53 A, so as to ensure that the working current of the motor 103 in the normal working stage is not too large.

[0039] In this embodiment, the control module 104 sets the initial short-circuit protection current value to 110A. When the user presses the trigger 105, the control module 104 detects the closing signal of the trigger 105 and controls the output of the driving duty cycle to drive the motor 103 to operate. The motor 103 is in the first operating stage. As the stroke of the trigger 105 increases, the speed of the motor 103 increases. When the control module 104 detects that the stroke of the trigger 105 is greater than or equal to 50%, it determines whether it lasts for 50ms. If so, the control module 104 controls the short-circuit protection current value to be switched to 53A, and the motor 103 is in the second operating stage. If not, the control module 104 controls the short-circuit protection current value to remain at 110A, and the motor 103 is in the first operating stage. The control module 104 continues to detect whether the trigger stroke lasts for 50ms until the short-circuit protection current value is switched to 53A, so that the motor 103 operates normally in the second operating stage.

[0040] The electric tool and control method of the present invention divide the motor operation into stages, and the user can set the short-circuit protection value at different stages, which meets the needs of the electric tool for large current at startup and relatively small stall protection and short-circuit protection values ​​during normal operation.

[0041] The present invention is not limited to the specific embodiments described above. Those skilled in the art will readily appreciate that numerous alternatives to the power tool and control method of the present invention exist without departing from the principles and scope of the present invention. The scope of protection of the present invention shall be determined by the claims.

Claims

1. A power tool comprising a housing, a motor located within the housing, a switch module connected to the motor, and a control module, wherein the control module detects an amount of operation of the switch module, stores a drive duty ratio corresponding to the amount of operation, and controls the motor to operate by outputting a corresponding drive duty ratio according to the amount of operation; characterized in that: The control module stores a first threshold, a second threshold, a third threshold and a predetermined time, wherein the second threshold is greater than the third threshold; the motor includes a first operating stage and a second operating stage, wherein the first operating stage and the second operating stage are respectively provided with different short-circuit protection values; when the switch module is closed, the motor is in the first operating stage, which is a soft start stage, and the control module sets the short-circuit protection value to the second threshold; when the control module detects that the operation amount of the switch module is greater than or equal to the first threshold and lasts for a predetermined time, the motor is controlled to switch to the second operating stage, which is the normal operating stage of the power tool; the control module sets the short-circuit protection value to the third threshold, and the second threshold is the maximum current value I of the motor in the first operating stage. 1max , the third threshold is the maximum current value I of the motor in the second operation stage 2max , and the second threshold I 1max Greater than the third threshold I 2max .

2. The electric tool according to claim 1, wherein: The second threshold I 1max is the initial value of the short-circuit protection value, that is, when the power tool starts working, the control module controls and sets the short-circuit protection value to I 1max .

3. A power tool control method, applied to the power tool according to claim 1 or 2, characterized in that: The control method includes: The control module detects the closed state of the switch module; The control module determines the working state of the motor according to the closed state; When the working state indicates that the motor is in a first operating stage, setting the short-circuit protection value to a second threshold value and obtaining the operation amount of the switch module, wherein the first operating stage is a soft start stage; when the operation amount of the switch module is greater than or equal to the first threshold value, obtaining the duration of the switch module being in the operation amount; When the duration reaches a predetermined time, the motor switches to a second operation stage and sets the short-circuit protection value to a third threshold value, wherein the second operation stage is a normal operation stage of the power tool; The second threshold is the maximum current value I of the motor in the first operation stage. 1max , the third threshold is the maximum current value I of the motor in the second operation stage 2max , and the second threshold I 1max Greater than the third threshold I 2max .

4. The power tool control method according to claim 3, wherein: The second threshold I 1max is the initial value of the short-circuit protection value, that is, when the power tool starts working, the control module controls and sets the short-circuit protection value to I 1max .

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