Speed regulating structure of electric tool

Abstract

The utility model discloses a speed regulation structure of an electric tool. The speed regulation structure comprises a metal soft magnetic material, a printed circuit board, a linear Hall sensor, a magnet and a push rod, the metal soft magnetic material is fixed on the front surface of the printed circuit board; the linear Hall sensor is welded on the back surface of the printed circuit board over against the metal soft magnetic material; the push rod is located on the back face of the printed circuit board and can linearly move in the front-back direction parallel to the printed circuit board. The magnet is fixed on the push rod and synchronously and linearly moves along with the push rod, and the moving path passes through the projection area of the linear Hall sensor away from the printed circuit board side. The speed regulation structure of the electric tool can realize vibration resistance and electromagnetic interference resistance while realizing a non-contact speed regulation function.

Description

Technical Field

[0001] The utility model relates to the technology of electric tools, in particular to a speed regulation structure of an electric tool. Background Art

[0002] Existing electric tools usually integrate a contact potentiometer (integrated on the printed circuit board where the electric tool controller is located or inside the electric tool switch) to achieve the speed regulation function. The potentiometer consists of a brush, a carbon film (or segmented resistor), and a handle for moving the brush. By moving the handle, the contact position between the brush and the carbon film (or segmented resistor) is changed, and the resistance value of the potentiometer is changed, thereby achieving the speed regulation function. Due to the use of a contact brush structure, under high vibration conditions, the service life of the brush, the gold finger, or the carbon film is low. Content of the Utility Model

[0003] The technical problem to be solved by the utility model is to provide a speed regulation structure of an electric tool, which can achieve non-contact speed regulation function while achieving anti-vibration and anti-electromagnetic interference.

[0004] To solve the above technical problem, the speed regulation structure of the electric tool provided by the utility model includes a metal soft magnetic material, a printed circuit board, a linear Hall sensor, a magnet, and a push rod;

[0005] The metal soft magnetic material is fixed on the front side of the printed circuit board;

[0006] The linear Hall sensor is welded to the back side of the printed circuit board facing the metal soft magnetic material;

[0007] The push rod is located on the back side of the printed circuit board and can move linearly in the front-back direction parallel to the printed circuit board;

[0008] The magnet is fixed on the push rod and moves linearly synchronously with the push rod, and the moving path passes through the projection area on the side far from the printed circuit board of the linear Hall sensor.

[0009] Preferably, the linear Hall sensor is welded to the back side of the printed circuit board by surface mount technology.

[0010] Preferably, the metal soft magnetic material is silicon steel, pure iron for electrical engineering, or permalloy.

[0011] Preferably, the speed regulation structure of the electric tool further includes a controller;

[0012] The printed circuit board is connected to the controller through a wire;

[0013] The controller controls the rotation speed of the electric tool according to the potential analog signal output by the linear Hall sensor.

[0014] Preferably, the rotational speed of the motor of the power tool is positively or negatively correlated with the amplitude of the potential analog signal output by the linear Hall sensor.

[0015] Preferably, the speed regulation structure of the power tool is integrated in a power tool switch;

[0016] The controller is arranged outside the power tool switch;

[0017] The linear Hall sensor is signal-connected to the controller through a wire.

[0018] Preferably, the linear Hall sensor and the controller are arranged on the same printed circuit board;

[0019] The linear Hall sensor is signal-connected to the controller through the printed circuit board traces.

[0020] Preferably, a return spring is arranged at the front end of the push rod;

[0021] When the magnet is in the initial position, the return spring is in a natural state;

[0022] When the push rod is pushed to move the magnet forward away from the above initial position, the return spring will be compressed and deformed to generate a backward deformation force.

[0023] In the speed regulation structure of the power tool of the present invention, the linear Hall sensor 3 is located between the metal soft magnetic material 1 and the magnet 4. When the push rod 5 moves linearly in the front-back direction parallel to the printed circuit board (PCB) 2, the magnet 4 moves linearly synchronously with the push rod 5. During the movement of the push rod 5, a variable coupling field is formed between the magnet 4 and the metal soft magnetic material 1. Every time the magnet 4 moves to a position, a magnetic coupling field is formed with the metal soft magnetic material 1, and a corresponding magnetic flux density will be formed at the position where the linear Hall sensor 3 is located, and its effective direction component is perpendicular to the direction of the Hall sensor 3. The linear Hall sensor 3 is in the coupling magnetic field and can output a corresponding potential analog signal. This power tool speed regulation structure can achieve anti-vibration, anti-electromagnetic interference and extend the service life while realizing the non-contact speed regulation function through a comprehensive magnetic element technical solution. This power tool speed regulation structure adopts a non-contact speed regulation function implementation scheme, which has no wear, anti-vibration, anti-electromagnetic interference, can extend the service life, improve the stability of speed regulation, has a more compact speed regulation function area, and can be widely used as a non-contact speed regulation switch in various speed regulation tools. Description of the Drawings

[0024] To more clearly illustrate the technical solution of the present utility model, the following briefly introduces the drawings required for the present utility model. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0025] Figure 1 It is a schematic diagram of the structure and push rod movement of an embodiment of the speed regulation structure of the electric tool of the present utility model;

[0026] Figure 2 It is a schematic diagram of the structure and magnet movement of an embodiment of the speed regulation structure of the electric tool of the present utility model;

[0027] Figure 3 It is a schematic diagram of a variable coupling field formed by a magnet and a metal soft magnetic material in an embodiment of the speed regulation structure of the electric tool of the present utility model;

[0028] Figure 4 It is a schematic diagram of a monotonically changing magnetic field formed at the position of the linear Hall sensor in an embodiment of the speed regulation structure of the electric tool of the present utility model.

[0029] Description of reference numerals:

[0030] 1 Metal soft magnetic material; 2 Printed circuit board; 3 Linear Hall sensor; 4 Magnet; 5 Push rod. Specific embodiments

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present utility model with reference to the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, rather than all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present utility model.

[0032] The "first", "second" and similar terms used in this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "including" or "comprising" mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right", "front", "rear", etc. are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0033] It should be noted that, without conflict, the embodiments in the present utility model and the features in the embodiments can be combined with each other.

[0034] Embodiment 1

[0035] As Figure 1 shown, the speed regulation structure of the electric tool includes a metal soft magnetic material 1, a printed circuit board (PCB) 2, a linear Hall sensor 3, a magnet 4 and a push rod 5;

[0036] The metal soft magnetic material 1 is fixed on the front side of the printed circuit board 2;

[0037] The linear Hall sensor 3 is welded to the back side of the printed circuit board 2 facing the metal soft magnetic material 1;

[0038] The push rod 5 is located on the back side of the printed circuit board 2 and can move linearly in the front-back direction parallel to the printed circuit board 2;

[0039] The magnet 4 is fixed on the push rod 5 and moves linearly synchronously with the push rod 5, and the moving path passes through the projection area on the side of the linear Hall sensor 3 away from the printed circuit board 2.

[0040] Preferably, the linear Hall sensor 3 is welded to the back side of the printed circuit board (PCB) 2 by surface mount technology (SMT).

[0041] For the speed regulation structure of the electric tool in Embodiment 1, the linear Hall sensor 3 is located between the metal soft magnetic material 1 and the magnet 4. When the push rod 5 moves linearly in the front-back direction parallel to the printed circuit board (PCB) 2, the magnet 4 moves linearly synchronously with the push rod 5; during the movement of the push rod 5, a variable coupling field is formed between the magnet 4 and the metal soft magnetic material 1. Every time the magnet 4 moves to a position, a magnetic coupling field is formed with the metal soft magnetic material 1, and a corresponding magnetic flux density will be formed at the position where the linear Hall sensor 3 is located, and its effective direction component is perpendicular to the direction of the Hall sensor 3. As Figure 3 shown. The linear Hall sensor 3 is in the coupling magnetic field and can output a corresponding potential analog signal.

[0042] The magnet 4 at the initial position forms an initial coupling magnetic field with the soft magnetic metal material 1. The linear Hall sensor 3 located between the soft magnetic metal material 1 and the magnet 4 can detect the magnetic flux density of the initial coupling magnetic field at a specific position, and thus output a corresponding analog potential signal of the initial position to the power tool controller; Operating the push rod 5 drives the magnet 4 to move linearly forward from the initial position to the starting position different from the initial position. The magnet 4 at the starting position forms a starting coupling magnetic field with the soft magnetic metal material 1. The linear Hall sensor 3 located between the soft magnetic metal material 1 and the magnet 4 can detect the magnetic flux density of the starting coupling magnetic field at a specific position, and thus output a corresponding analog potential signal of the starting position to the power tool controller; Operating the push rod 5 drives the magnet 4 to move linearly forward from the starting position to the termination position different from the starting position. The magnet 4 at the termination position forms a termination coupling magnetic field with the soft magnetic metal material 1. The linear Hall sensor 3 located between the soft magnetic metal material 1 and the magnet 4 can detect the magnetic flux density of the termination coupling magnetic field at a specific position, and thus output a corresponding analog potential signal of the termination position to the power tool controller.

[0043] By designing and calculating the initial position of the magnet 4 relative to the soft magnetic metal material 1, it can be realized that during the forward linear motion process of the magnet 4 from the initial position to the starting position and then to the termination position, the magnetic flux density at the position where the linear Hall sensor 3 is located has a monotonic distribution characteristic, as Figure 4 shown, the linear Hall sensor 3 will output a corresponding monotonically changing analog potential signal. By selecting a linear Hall sensor 3 with an appropriate magnetic flux, the corresponding effective magnetic flux density range can be intercepted, and a corresponding monotonically changing (increasing or decreasing) analog potential signal is output to the power tool controller. This monotonically changing analog potential signal can be combined with the function of the power tool controller to control the output speed of the power tool by moving the push rod 5, realizing a non-contact speed regulation function.

[0044] The soft magnetic metal material 1 has the characteristics of high magnetic permeability and low coercivity, is easy to magnetize and demagnetize, and can effectively resist external electromagnetic field interference. Therefore, the position where the linear Hall sensor 3 is located in the coupling magnetic field region can reduce external electromagnetic interference.

[0045] The speed control structure of the power tool in Embodiment 1 can achieve anti-vibration, anti-electromagnetic interference and extended service life while realizing the non-contact speed control function through a comprehensive magnetic element technical solution. The speed control structure of the power tool adopts a non-contact speed control function implementation solution, which has no wear, anti-vibration, anti-electromagnetic interference, can extend the service life, improve the stability of speed control, has a more compact speed control function area, and can be widely used as a non-contact speed control switch in various speed control tools. It can be applied to power tools or related electromechanical products, especially hand-held power tools such as electric screwdrivers, electric angle grinders, electric drilling machines, electric wrenches or similar products. The speed control structure of the power tool is often integrated into the handle.

[0046] Embodiment 2

[0047] Based on the speed control structure of the power tool in Embodiment 1, the metal soft magnetic material 1 is silicon steel (iron-silicon alloy), electrolytic iron, pure carbon steel or permalloy, etc.

[0048] In the speed control structure of the power tool in Embodiment 2, silicon steel has a high magnetic permeability and a low coercive force. The hysteresis loop is narrow and steep, the magnetization process is close to reversible, and the hysteresis loss is small. The high magnetic permeability is conducive to forming a stable magnetic coupling field with the magnet 4 to resist external magnetic field interference; the low coercive force can quickly form a magnetic coupling field with the magnet 4 to reduce the influence of hysteresis and eddy currents and adapt to different operating speeds.

[0049] Embodiment 3

[0050] Based on the speed control structure of the power tool in Embodiment 1, the speed control structure of the power tool further includes a controller;

[0051] The linear Hall sensor 3 is signal-connected to the controller;

[0052] The controller controls the rotation speed of the power tool according to the potential analog signal output by the linear Hall sensor 3.

[0053] Preferably, the motor rotation speed of the power tool is positively or negatively correlated with the amplitude of the potential analog signal output by the linear Hall sensor 3.

[0054] Embodiment 4

[0055] Based on the speed control structure of the power tool in Embodiment 3, the speed control structure of the power tool is integrated in an electric tool switch;

[0056] The controller is arranged outside the electric tool switch;

[0057] The printed circuit board 2 is connected to the controller through a wire, so as to connect the linear Hall sensor 3 to the controller.

[0058] Preferably, the controller powers the linear Hall sensor 3, and the linear Hall sensor 3 outputs an analog potential signal to the controller.

[0059] Embodiment Five

[0060] Based on the speed regulation structure of the electric tool in Embodiment Three, the linear Hall sensor 3 and the controller are arranged on the same printed circuit board 2.

[0061] Embodiment Six

[0062] Based on the speed regulation structure of the electric tool in Embodiment One, a return spring is arranged at the front end of the push rod 5;

[0063] When the magnet 4 is in the initial position, the return spring is in a natural state;

[0064] When the push rod 5 is pushed to make the magnet 4 move forward away from the above initial position, the return spring will be compressed and deformed to generate a backward deformation force.

[0065] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A speed regulating structure for an electric tool, characterized in that: It comprises a metal soft magnetic material (1), a printed circuit board (2), a linear Hall sensor (3), a magnet (4) and a push rod (5); The metallic soft magnetic material (1) is fixed on the front side of the printed circuit board (2); The linear Hall sensor (3) is welded on the back side of the printed circuit board (2) facing the metal soft magnetic material (1); The push rod (5) is located on the back side of the printed circuit board (2) and can move linearly along the front-rear direction parallel to the printed circuit board (2); The magnet (4) is fixed on the push rod (5), moves synchronously with the push rod (5) in a straight line, and the moving path passes through the projection area of ​​the linear Hall sensor (3) away from the printed circuit board (2).

2. The electric tool speed regulating structure according to claim 1, characterized in that: The linear Hall sensor (3) is welded on the back side of the printed circuit board (2) using a surface mounting process.

3. The electric tool speed regulating structure according to claim 1, characterized in that: The metallic soft magnetic material (1) is silicon steel, electrical pure iron or Permalloy.

4. The electric tool speed regulating structure according to claim 1, characterized in that: The electric tool speed regulation structure also includes a controller; The printed circuit board (2) is connected to the controller via a wire; The controller controls the rotation speed of the electric tool according to the potential analog signal output by the linear Hall sensor (3).

5. The electric tool speed regulating structure according to claim 4, characterized in that: The motor speed of the electric tool is positively correlated or negatively correlated with the amplitude of the potential analog signal output by the linear Hall sensor (3).

6. The electric tool speed regulating structure according to claim 4, characterized in that: The electric tool speed regulating structure is integrated into an electric tool switch; The controller is arranged outside the electric tool switch; The linear Hall sensor (3) is connected to the controller via a wire signal.

7. The electric tool speed regulating structure according to claim 4, characterized in that: The linear Hall sensor (3) and the controller are arranged on the same printed circuit board (2); The linear Hall sensor (3) is connected to the controller signal via a printed circuit board wiring.

8. The electric tool speed regulating structure according to claim 1, characterized in that: A return spring is arranged at the front end of the push rod (5); When the magnet (4) is in the initial position, the return spring is in a natural state; When the push rod (5) is pushed to make the magnet (4) move forward away from the initial position, the return spring will be compressed and deformed to generate a backward deformation force.

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