Electric tool

Abstract

The application discloses an electric tool, comprising: a motor comprising a rotor and a multi-phase stator winding; the driving circuit is electrically connected with a stator winding of the motor and comprises at least one switch element; the electric tool further comprises a first circuit board and a second circuit board, wherein at least one switch element is arranged on the first circuit board; and the Hall current sensor is used for detecting the current of the driving circuit, and the Hall current sensor is arranged outside the first circuit board. By the adoption of the technical scheme, the electric tool can be provided, and the continuous working performance is high.

Description

Technical Field

[0001] The present application relates to the technical field of tools, and in particular to an electric tool. Background Art

[0002] Compared with engine-type tools, electric tools are more environmentally friendly and thus widely used. The motor is driven by current, and the driving force of the motor is transmitted to the working part of the electric tool, so that the electric tool works. When designing electric tools, it is necessary to detect the current in order to achieve corresponding control and protection of the electric tools. The current commonly used method is to use a current sensing resistor to detect the current. However, when the current is large, the current sensing resistor will have a large loss, resulting in an increase in the temperature of the circuit board where it is located, and the performance of the continuous working time of the electric tool is reduced.

[0003] This section provides background information related to the present application which is not necessarily prior art. Utility Model Content

[0004] One object of the present application is to solve or at least alleviate part or all of the above problems. To this end, one object of the present application is to provide an electric tool with high continuous working performance.

[0005] In order to achieve the above objectives, the present application adopts the following technical solution: an electric tool, comprising:

[0006] The motor includes a rotor and a multi-phase stator winding; the drive circuit is electrically connected to the stator winding of the motor and includes at least one switching element; the power tool also includes: a first circuit board, on which at least one switching element is arranged; a Hall current sensor, used to detect the current of the drive circuit, and the Hall current sensor is arranged outside the first circuit board.

[0007] In some embodiments, the electric tool further includes a second circuit board, and the Hall current sensor is disposed on the second circuit board.

[0008] In some embodiments, the distance between the second circuit board and the first circuit board is less than or equal to 50 mm.

[0009] In some embodiments, the Hall current sensor is disposed on the copper foil conductor of the second circuit board.

[0010] In some embodiments, the Hall current sensor is disposed on a wire electrically connecting the drive circuit to the stator winding of the motor.

[0011] In some embodiments, an electric tool includes: a motor, including a rotor and a multi-phase stator winding; a drive circuit, electrically connected to the stator winding of the motor, including at least one switching element; the electric tool also includes: a first circuit board, on which at least one switching element is disposed; a Hall current sensor, for detecting the current of the drive circuit, the Hall current sensor being disposed on the first circuit board, and a distance from at least one switching element or a copper foil conductor of the first circuit board being less than or equal to 50 mm.

[0012] In some embodiments, when the Hall current sensor is disposed on the first circuit board, it detects the current of the driving circuit when at least one switching element is turned on or off.

[0013] In some embodiments, the at least one switching element includes a high-side switching element and / or a low-side switching element.

[0014] In some embodiments, one end of the copper foil conductor is connected to the low-side switching element, and the other end of the copper foil conductor is grounded. The Hall current sensor is arranged on the first circuit board, and when the distance from the copper foil conductor is less than or equal to 50 mm, the current of the driving circuit is detected when the low-side switching element is opened or closed.

[0015] In some embodiments, one end of the copper foil conductor is connected to the high-side switching element, and the other end of the copper foil conductor is connected to the stator winding of the motor. The Hall current sensor is arranged on the first circuit board, and when the distance from the copper foil conductor is less than or equal to 50 mm, the freewheeling current of the driving circuit is detected.

[0016] The benefit of the present application lies in that: by using a Hall current sensor to detect the current in the power tool, the heat loss can be reduced based on the characteristics of the Hall current sensor, and the continuous working time of the power tool can be increased. At the same time, it can be set outside the first circuit board and the position arrangement is flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a side view of an electric tool according to an embodiment;

[0018] Figure 2 is a circuit block diagram of an electric tool according to an embodiment;

[0019] Figure 3 is a schematic diagram of a Hall current sensor of an embodiment being arranged on a second circuit board;

[0020] Figure 4 It is a circuit block diagram of a Hall current sensor of an electric tool for detecting phase current according to an embodiment;

[0021] Figure 5 is a schematic diagram of a Hall current sensor of an embodiment being arranged on a copper foil conductor on a first circuit board;

[0022] Figure 6 The Hall current sensor of an embodiment is arranged on the first circuit board and is spaced from the copper foil conductor.

[0023] Schematic diagram of D2;

[0024] Figure 7 is a schematic diagram of a Hall current sensor of an embodiment being arranged on a first circuit board at a distance D3 from a switch element;

[0025] Figure 8 It is a circuit block diagram of a Hall current sensor of an electric tool according to an embodiment of the present invention, which is arranged on a copper foil conductor connected to a low-side switching element;

[0026] Fig. 9 The present invention is a circuit block diagram of an electric tool in which a Hall current sensor is arranged on a copper foil conductor connected to a high-side switching element according to an embodiment. DETAILED DESCRIPTION

[0027] Before any embodiments of the application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the above drawings.

[0028] In this application, the terms "comprises", "includes", "has" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0029] In this application, the term "and / or" is a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects before and after are in an "and / or" relationship.

[0030] In the present application, the terms "connect", "combine", "couple", and "install" may refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, direct connection refers to two parts or components being connected together without the need for an intermediate piece, and indirect connection refers to two parts or components being connected to at least one intermediate piece respectively, and the two parts or components being connected via the intermediate piece. In addition, "connect" and "couple" are not limited to physical or mechanical connections or couplings, and may include electrical connections or couplings.

[0031] In the present application, it will be understood by those of ordinary skill in the art that relative terms (e.g., "about," "approximately," "substantially," etc.) used in conjunction with quantities or conditions include the values ​​and have the meaning indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a specific value, the tolerances caused by manufacturing, assembly, and use associated with a specific value, and the like. Such terms should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to plus or minus a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. In addition, "substantially" may refer to plus or minus a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) on the basis of the indicated angle when expressing a relative angular position relationship (e.g., substantially parallel, substantially perpendicular).

[0032] In this application, it will be understood by those skilled in the art that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0033] In the present application, the terms "upper", "lower", "left", "right", "front", "back" and other directional words are described based on the orientation and positional relationship shown in the accompanying drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element. It should also be understood that directional words such as upper side, lower side, left side, right side, front side, back side, etc. not only represent the positive orientation, but can also be understood as the lateral orientation. For example, the bottom can include directly below, lower left, lower right, lower front, and lower back, etc.

[0034] In this application, the terms "controller", "processor", "central processing unit", "CPU", and "MCU" are interchangeable. When a unit "controller", "processor", "central processing unit", "CPU", or "MCU" is used to perform a specific function, unless otherwise specified, these functions can be performed by a single unit or multiple units.

[0035] In the present application, the terms “device”, “module” or “unit” may be implemented in the form of hardware or software to achieve specific functions.

[0036] In this application, the terms "calculate", "judge", "control", "determine", "identify", etc. refer to the operations and processes of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0037] In the present application, motor windings or stator windings or windings all represent metal windings in the motor. Unless otherwise specified, the above-mentioned names for metal windings can be used universally.

[0038] The electric tools to which the technical solution of the present application applies include handheld electric tools, fastening electric tools, cutting electric tools, grinding electric tools, etc. For example, electric tools such as hair dryers, electric drills, electric circular saws, reciprocating saws, impact wrenches, impact screwdrivers, and hammer drills. Other types of electric tools can fall within the scope of protection of the present application as long as they can adopt the essential content of the technical solution disclosed below. In the embodiments of the present application, reference is made to Figure 1 Taking an impact power tool as an example, the power tool 100 includes at least a housing 10, a motor 11 in the housing, a power source 12, a switch, a working head, etc. The housing 10 includes a motor 11, a control circuit board, and a transmission structure (not shown). The housing 10 also includes a grip for a user to hold. The motor 11 includes a rotor and a multi-phase stator winding.

[0039] refer to Figure 2 As shown in the circuit block diagram of the electric tool, the driving system of the motor 11 may at least include a driving circuit 20 , a power supply 12 and a controller 21 .

[0040] In some embodiments, the motor 11 is a brushed DC motor. In some embodiments, the motor 11 is a brushless DC motor (BLDC). In some embodiments, the motor 11 is an inductive BLDC. In some embodiments, the motor 11 is an inductive BLDC. In the present application, the brushless DC motor can be an inner rotor motor or an outer rotor motor, and the motor 11 includes at least three-phase stator windings A, B, and C, and the three-phase windings can be star-connected or delta-connected.

[0041] In some embodiments, the power supply 12 can be selected as an AC power supply, that is, a 120V or 220V AC mains power supply can be connected through a power interface. In some embodiments, the power supply 12 can be selected as a battery pack, and the battery pack can be composed of a group of battery cells. For example, the battery cells can be connected in series into a single power branch to form a 1P battery pack. In the present application, the power supply 12 is taken as an example of a battery pack for specific description. The output voltage of the battery pack is changed through a specific power control module, such as a DC-DC module, and a power supply voltage suitable for the drive circuit 20, the motor 11, etc. is output to power them. Those skilled in the art will understand that the DC-DC module is a mature circuit structure and can be selected accordingly according to the specific parameter requirements of the power tool.

[0042] The drive circuit 20 is electrically connected to the stator windings A, B, and C of the motor 11, and is used to transfer current from the power supply 12 to the stator windings A, B, and C to drive the motor 11 to rotate. In some embodiments, the drive circuit 20 includes at least one switch element 201, and the present application does not limit the switch element 201. In some embodiments, the at least one switch element 201 includes a high-side switch element and / or a low-side switch element. In some embodiments, as Figure 2 As shown, the drive circuit 20 includes a plurality of switch elements Q1, Q2, Q3, Q4, Q5, and Q6. Among them, the switch elements Q1, Q3, and Q5 are high-side switch elements, and Q2, Q4, and Q6 are low-side switch elements. Any phase stator winding of the motor 11 is connected to a high-side switch element and a low-side switch element.

[0043] The gate terminal of each switching element in the drive circuit 20 is electrically connected to the controller 21 for receiving a control signal from the controller 21. The drain or source of each switching element is connected to the stator windings A, B, and C of the motor 11. The switch elements Q1-Q6 receive control signals from the controller 21 to change their respective conduction states, thereby changing the current loaded by the power supply 12 on the stator windings A, B, and C of the motor 11. In some embodiments, the drive circuit 20 can be a three-phase bridge driver circuit including six controllable semiconductor power devices (such as FET, BJT, IGBT, etc.). It can be understood that the above-mentioned switch elements can also be any other type of solid-state switches, such as insulated gate bipolar transistors (IGBTs), bipolar junction transistors (BJTs), etc.

[0044] After the power tool 100 is started, a high-side switch element and a low-side switch element connected to different windings in the drive circuit 20 are turned on. When the motor 11 is switched on, due to the internal inductance of the motor 11, the phase current on the winding will not suddenly change to zero after the phase change, and then the body diode connected in parallel with the turned-off switch element will continue to flow.

[0045] like Figure 3As shown, the electric tool 100 includes a first circuit board 30, and the switching elements Q1-Q6 can all be arranged on the first circuit board 30. The electric tool 100 also includes a Hall current sensor 40, and the Hall current sensor 40 is used to detect the current in the drive circuit 20, so that when the electric tool 100 is working, the electric tool 100 can be protected and controlled accordingly based on the current detected by the Hall current sensor 40. Optionally, when the current in the drive circuit 20 is greater than 50A, the Hall current sensor 40 is used to detect the current. When the current is less than or equal to 50A, a current sensing resistor can be used to detect the current. Therefore, when the current in the drive circuit 20 is large, the use of the Hall current sensor 40 can avoid the problem of continuous heating and large loss of the current sensing resistor when the current is large. The Hall current sensor 40 has a longer continuous working time, so that the continuous working performance of the electric tool 100 is higher

[0046] In some embodiments, the Hall current sensor 40 can be arranged outside the first circuit board 30 to detect the current of the driving circuit 20, that is, the Hall current sensor 40 can be arranged outside the circuit board with a large current to detect the current of the driving circuit on the circuit board. Figure 3 As shown, the electric tool 100 also includes a second circuit board 50, and the Hall current sensor 40 can be arranged on the second circuit board 50 to detect the current of the drive circuit 20. At this time, the distance D1 between the second circuit board 50 and the first circuit board 30 needs to be less than or equal to 50mm. Specifically, the distance between the position A of the Hall current sensor 40 on the second circuit board 50 and the position B of the drive circuit 20 on the first circuit board 30 where the current needs to be detected is less than or equal to 50mm. Thus, the Hall current sensor 40 can more accurately detect the current at the position where the current needs to be detected in the drive circuit 20. Optionally, the second circuit board 50 can be located at any position with a distance less than or equal to 50mm around the position where the current needs to be detected on the first circuit board 30 as the center. Optionally, the second circuit board 50 can be located above the first circuit board 30. Optionally, the second circuit board 50 can be located below the first circuit board 30. Optionally, the second circuit board 50 can be located on the left side of the first circuit board 30. Optionally, the second circuit board 50 can be located on the right side of the first circuit board 30. Optionally, the second circuit board 50 may be located at the upper left of the first circuit board 30 .

[0047] In some embodiments, when the Hall current sensor 40 is disposed on the second circuit board 50, specifically, the Hall current sensor 40 can be disposed on a copper foil conductor 51 on the second circuit board 50 (i.e., a connecting copper wire on the second circuit board 50), and the Hall current sensor 40 can be placed on the copper foil conductor 51 and connected to the copper foil conductor 51.

[0048] In some embodiments, when the Hall current sensor 40 is disposed outside the first circuit board 30, it can also be disposed on a wire electrically connecting the drive circuit 20 and the stator winding of the motor 11. Specifically, the Hall current sensor 40 can be directly wound around the wire to detect the phase current of the drive circuit 20. In some embodiments, when the Hall current sensor 40 is disposed outside the first circuit board 30, it can also sense and detect the bus current of the drive circuit 20. Figure 4 As shown, optionally, the Hall current sensor 40 can be arranged on the wire electrically connecting the drive circuit 20 and the stator winding A of the motor 11 to detect the phase current of the A phase. Optionally, the Hall current sensor 40 can be arranged on the wire electrically connecting the drive circuit 20 and the stator winding B of the motor 11 to detect the phase current of the B phase. Optionally, the Hall current sensor 40 can be arranged on the wire electrically connecting the drive circuit 20 and the stator winding C of the motor 11 to detect the phase current of the C phase. Optionally, there can be multiple Hall current sensors 40 in the power tool 100 to detect the phase currents of the A phase, the B phase and the C phase at the same time. Optionally, there can be two Hall current sensors 40 in the power tool 100 to detect the phase currents of any two phases of the A phase, the B phase and the C phase at the same time. Optionally, there can also be only one Hall current sensor 40 in the power tool 100 for detecting the phase current of any one phase of the A phase, the B phase and the C phase.

[0049] By arranging the Hall current sensor 40 outside the first circuit board 30, the area of ​​the first circuit board 30 can be reduced. At the same time, by using the Hall current sensor 40 to detect the current, the position of the Hall current sensor 40 can be flexibly arranged.

[0050] In some embodiments, the Hall current sensor 40 can also be disposed on the first circuit board 30, and when the distance from at least one switch element 201 or the copper foil conductor 31 (i.e., the connecting copper wire on the first circuit board 30) is less than or equal to 50 mm, the current of the drive circuit 20 is detected when at least one switch element 201 is turned on or off. The Hall current sensor 40 can be located at any position with a distance of less than or equal to 50 mm around the switch element 201 or the copper foil conductor 31. Optionally, as Figure 5 As shown, the Hall current sensor 40 is disposed on the copper foil conductor 31 on the first circuit board 30 to detect the current. Figure 6 As shown, the Hall current sensor 40 is arranged on the first circuit board 30 at a distance D2 from the copper foil conductor 31 to detect the current. Wherein, D2 is less than or equal to 50 mm. Optionally, as Figure 7As shown, the Hall current sensor 40 is disposed on the first circuit board 30, and senses the current on the switch 201 at a distance D3 from the switch element 201. Wherein, D3 is less than or equal to 50 mm, and D3 is not equal to 0 mm. Since the switch element 201 has a certain height, the Hall current sensor 40 cannot be directly disposed on the switch element 201, and needs to maintain a certain distance from the switch element 201 to sense the current on the switch element 201.

[0051] In some embodiments, when at least one switching element 201 includes a high-side switching element and / or a low-side switching element, the Hall current sensor 40 can be set at a position greater than 0 mm and less than or equal to 50 mm away from the high-side switching element and / or the low-side switching element to detect the current of the driving circuit 20.

[0052] In some embodiments, when one end of the copper foil conductor 31 is connected to the low-side switch element and the other end is grounded, the Hall current sensor 40 can be set at a position less than or equal to 50 mm from the copper foil conductor 31 to detect the current of the drive circuit 20 when the low-side switch element is turned on or off. This application is specifically described as the Hall current sensor 40 is set on the copper foil conductor 31.

[0053] like Figure 8As shown, the Hall current sensor 40 can be arranged on a copper foil conductor 31 connected to the low-side switch element Q6 at one end and connected to the ground at the other end, so as to detect the current flowing from the high-side switch element Q3 or Q5 to the low-side switch element Q6. At this time, since the Hall current sensor 40 can detect the current in real time, the current can be detected when the low-side switch element Q6 is turned on or off, so as to detect the current when the low-side switch element Q6 is turned off, so that the duty cycle of the upper bridge high-side switch element Q3 or Q5 is 1, thereby improving the utilization rate of the voltage. Optionally, the Hall current sensor 40 can also be arranged on a copper foil conductor 31 connected to the low-side switch element Q4 at one end and connected to the ground at the other end, so as to detect the current flowing from the high-side switch element Q1 or Q5 to the low-side switch element Q4. Optionally, the Hall current sensor 40 can also be arranged on a copper foil conductor 31 connected to the low-side switch element Q2 at one end and connected to the ground at the other end, so as to detect the current flowing from the high-side switch element Q1 or Q3 to the low-side switch element Q2. The power tool 100 can have multiple Hall current sensors 40, which are simultaneously arranged on the copper foil conductor 31 connected to the three low-side switch elements Q4, Q6 and Q2. Optionally, the power tool 100 can have two Hall current sensors 40, which are simultaneously arranged on the copper foil conductor 31 connected to any two of the three low-side switch elements Q4, Q6 and Q2. Optionally, the power tool 100 can also have only one Hall current sensor 40, which is arranged on the copper foil conductor 31 connected to any one of the three low-side switch elements Q4, Q6 and Q2.

[0054] In some embodiments, when one end of the copper foil conductor 31 is connected to the high-side switch element and the other end is connected to the stator winding of the motor 11, the Hall current sensor 40 can be set at a position less than or equal to 50 mm from the copper foil conductor 31 to detect the freewheeling current of the drive circuit 20. This application is specifically described as the Hall current sensor 40 is set on the copper foil conductor 31.

[0055] like Fig. 9As shown, the Hall current sensor 40 can be arranged on a copper foil conductor 31 connected to the high-side switch element Q1 at one end and connected to the stator winding of the motor 11 at the other end, to detect the freewheeling current flowing through the high-side switch element Q1. Optionally, the Hall current sensor 40 can also be arranged on a copper foil conductor 31 connected to the high-side switch element Q3 at one end and connected to the stator winding of the motor 11 at the other end, to detect the freewheeling current flowing through the high-side switch element Q3. Optionally, the Hall current sensor 40 can also be arranged on a copper foil conductor 31 connected to the high-side switch element Q5 at one end and connected to the stator winding of the motor 11 at the other end, to detect the freewheeling current flowing through the high-side switch element Q5. There can be multiple Hall current sensors 40 in the power tool 100, which are arranged on the copper foil conductor 31 connected to the three high-side switch elements Q1, Q3 and Q5 at the same time. Optionally, the power tool 100 may have two Hall current sensors 40, which are simultaneously arranged on the copper foil conductor 31 connected to any two of the three high-side switching elements Q1, Q3 and Q5. Optionally, the power tool 100 may also have only one Hall current sensor 40, which is arranged on the copper foil conductor 31 connected to any one of the three high-side switching elements Q1, Q3 and Q5. Based on the freewheeling current detected by the Hall current sensor 40, the inductance of the motor 11 can be determined, and the parameters of the motor 11 can be identified, so that when the parameters of the motor 11 change, the control strategy of the motor 11 can be changed in real time.

[0056] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the above embodiments do not limit the present application in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. An electric tool comprising: An electric machine, including a rotor and a multi-phase stator winding; a drive circuit, electrically connected to the stator winding of the motor, comprising at least one switching element; Characterized in that the electric tool also includes: a first circuit board, on which the at least one switching element is disposed; A Hall current sensor is used to detect the current of the driving circuit, and the Hall current sensor is arranged outside the first circuit board.

2. The electric tool according to claim 1, characterized in that: The electric tool further includes a second circuit board, and the Hall current sensor is arranged on the second circuit board.

3. The electric tool according to claim 2, characterized in that: The distance between the second circuit board and the first circuit board is less than or equal to 50 mm.

4. The electric tool according to claim 2, characterized in that: The Hall current sensor is arranged on the copper foil conductor of the second circuit board.

5. The electric tool according to claim 1, wherein: The Hall current sensor is arranged on a wire electrically connecting the drive circuit and the stator winding of the motor.

6. An electric tool comprising: An electric machine, including a rotor and a multi-phase stator winding; a drive circuit, electrically connected to the stator winding of the motor, comprising at least one switching element; Characterized in that the electric tool also includes: a first circuit board, on which the at least one switching element is disposed; A Hall current sensor is used to detect the current of the driving circuit. The Hall current sensor is arranged on the first circuit board and the distance between the Hall current sensor and the at least one switching element or the copper foil conductor of the first circuit board is less than or equal to 50 mm.

7. The electric tool according to claim 6, characterized in that: When the Hall current sensor is disposed on the first circuit board, it detects the current of the drive circuit when the at least one switching element is turned on or off.

8. The electric tool according to claim 6, wherein: The at least one switching element includes a high-side switching element and / or a low-side switching element.

9. The electric tool according to claim 8, characterized in that: One end of the copper foil conductor is connected to the low-side switching element, and the other end of the copper foil conductor is grounded. The Hall current sensor is arranged on the first circuit board, and when the distance from the copper foil conductor is less than or equal to 50 mm, the Hall current sensor detects the current of the drive circuit when the low-side switching element is turned on or off.

10. The electric tool according to claim 8, wherein: One end of the copper foil conductor is connected to the high-side switching element, and the other end of the copper foil conductor is connected to the stator winding of the motor. The Hall current sensor is arranged on the first circuit board, and detects the freewheeling current of the drive circuit when the distance from the copper foil conductor is less than or equal to 50 mm.

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