Balancing structure and method of electric power tool and electric power tool

Abstract

The application provides a balancing structure and method of an electric tool and the electric tool, which comprises a driving module, a crank connecting rod module and an output module, the crank connecting rod module is used to convert the rotary motion of the driving module into the linear motion of the output module, the output module acts on a processing object, and the balancing structure comprises two oppositely arranged balancing mechanisms, the balancing mechanism comprises a transmission gear and a counterweight, the driving module drives the transmission gear to rotate, the counterweight can rotate with the transmission gear, wherein the rotating directions of the two transmission gears in the two balancing mechanisms are opposite, and the counterweight is eccentrically arranged relative to the transmission gear. The application has good damping function, the rotating speed of the counterweight forms a variable angular speed, the unbalanced inertial force generated by the counterweight is two-order inertial force, the two-order inertial force can be completely counteracted by the output inertial force of the output module, so that the effect of reducing vibration is achieved.

Description

Technical Field

[0001] This invention relates to the field of power tool technology, and in particular to a power tool balancing structure, balancing method, and corresponding power tool. Background Technology

[0002] Currently, traditional power tools, taking reciprocating structures as an example, output reciprocating motion. Since most power tools are powered by motors, the drive is rotational. This conversion from rotation to linear motion requires different types of linkage mechanisms, which inevitably introduce imbalances. Therefore, these products tend to vibrate significantly, severely impacting the user experience. Currently, products on the market use balancing structures such as... Figure 8 As shown, the principle is to add a counterweight to the reciprocating joint and calculate the force of the counterweight in the reciprocating direction to counteract the output unbalanced force. However, the counterweight thus generates a force perpendicular to the reciprocating motion direction. Therefore, this scheme actually transfers the unbalanced force to other directions, and the effect of improving vibration is not significant. Therefore, there is an urgent need for a balancing structure that can fundamentally counteract vibration rather than simply transfer it. Summary of the Invention

[0003] To avoid the shortcomings of existing technologies, this invention provides a balancing structure for power tools that uses a variable angular velocity structure to counteract unbalanced forces.

[0004] The present invention solves the technical problem by adopting the following technical solution: a balancing structure for an electric tool, comprising a drive module, a crank-connecting rod module, and an output module. The crank-connecting rod module is used to convert the rotational motion of the drive module into the linear motion of the output module. The output module acts on the workpiece. The tool also includes two balancing mechanisms arranged opposite to each other. Each balancing mechanism includes a transmission gear and a counterweight. The drive module drives the transmission gear to rotate, and the counterweight can rotate with the transmission gear. The two transmission gears in the two balancing mechanisms rotate in opposite directions, and the counterweight is eccentrically arranged relative to the transmission gear.

[0005] In several embodiments, the balancing mechanism further includes a connecting body, one side of which protrudes outward to form a first shaft. A shaft hole is provided through the first shaft along its axial direction, and a second shaft is inserted into the shaft hole. The counterweight is sleeved on the first shaft and rotates around the first shaft. The second shaft is connected to and coaxially arranged with a transmission gear, and the shaft hole is eccentrically arranged relative to the first shaft.

[0006] In several embodiments, a transmission body is provided protruding on one side of the transmission gear, and a transmission groove is provided recessed inward on one side of the counterweight. The transmission body and the transmission groove cooperate to form a sliding pair.

[0007] In several embodiments, the two transmission gears are configured to rotate synchronously driven by the output shaft of the drive module. The two transmission gears are located on opposite sides of the motion plane of the crank-connecting rod module and drive the two counterweights to rotate in opposite directions.

[0008] In several embodiments, the balancing mechanism further includes a main gear, a drive shaft, a secondary gear, and an intermediate gear. The main gear and the secondary gear are connected by the drive shaft and are coaxially arranged. The main gear is configured to be driven to rotate by the output shaft of the drive module. One of the drive gears meshes with the secondary gear, and the other drive gear meshes with the intermediate gear. The intermediate gear meshes with the secondary gear. The two drive gears are located on both sides of the drive shaft and drive the two counterweights to rotate in opposite directions.

[0009] In several embodiments, a guide pin is eccentrically disposed on one side of one of the transmission gears, and the crank connecting rod module is rotatably connected to the guide pin.

[0010] In several embodiments, a second guide pin is eccentrically disposed on one side of the main gear, and the crank connecting rod module is rotatably connected to the second guide pin.

[0011] Furthermore, a balancing method based on the aforementioned balancing structure, wherein the balancing structure is used to counteract unbalanced forces during the operation of power tools, and the balancing method performs balancing according to the following balancing formula:

[0012]

[0013] Where M is the equivalent mass of the output module, R is the crank length, k = r / e, r is the equivalent radius of the counterweight, i.e. the radius of rotation of its center of mass, e is the distance between the rotation center of the counterweight and the rotation center of the transmission gear, x is the proportion of the counterweight's balancing weight, y is the proportion of the transmission gear's balancing weight, and the boundary condition is min(x+y).

[0014] In several embodiments, the balancing formula includes the following calculation process:

[0015] Let ΣF = 0, calculate the values ​​of x, y, and k, and take the values ​​of wt as 0° and 180°. Combining the weights x and y, we obtain the following equation:

[0016]

[0017] Obtain the values ​​of x, y, and k, and perform calculations under the following conditions:

[0018] m1r1=y·MR;

[0019] mr=x·MR; where m is the equivalent mass of the counterweight, m1 is the equivalent mass of the transmission gear, and r1 is the equivalent radius of the transmission gear, i.e., the radius of rotation of its center of mass.

[0020] Based on the obtained r and the calculated k value, the e value is obtained.

[0021] Furthermore, an electric tool employing the aforementioned balancing structure also includes components such as a housing.

[0022] The present invention has the following beneficial effects:

[0023] 1. This invention has a good vibration reduction function. Through two symmetrically arranged balancing mechanisms with opposite rotation directions, and the eccentric rotational motion of the transmission gear and the counterweight in the balancing mechanism, the rotational speed of the counterweight and the rotational speed of the transmission gear are made different. The rotational speed of the counterweight forms a variable angular velocity, so that the unbalanced inertial force generated by the counterweight is a second-order inertial force, which can completely cancel out the output inertial force of the output module, thereby achieving the effect of reducing vibration.

[0024] 2. The present invention has a stable structure, strong portability, and is easy to install on various power tools. Attached Figure Description

[0025] The accompanying drawings described herein are for illustrative purposes only and do not represent all possible implementations, nor should they be considered as limiting the scope of the invention.

[0026] Figure 1 The overall structure of the power tool in Embodiment 1 is illustrated schematically;

[0027] Figure 2 Schematic illustration Figure 1 An enlarged structure of the central balancing structure;

[0028] Figure 3 Schematic illustration Figure 2 The explosive structure;

[0029] Figure 4 Schematic illustration Figure 3 The explosive structure of the balancing mechanism;

[0030] Figure 5 Schematic illustration Figure 4 Partial explosive structure;

[0031] Figure 6 Schematic illustration Figure 5 Top view of the central connecting structure;

[0032] Figure 7 The exploded structure of the balancing structure in Example 2 is illustrated schematically;

[0033] Figure 8 A schematic diagram illustrating the motion of an existing balancing structure is shown.

[0034] Figure 9 A schematic diagram of the motion of the balancing structure in Embodiment 3 is shown. Detailed Implementation

[0035] The embodiments of the present invention will be described in detail below. In order to make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0036] Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0037] The terminology used herein is intended to explain the embodiments and is not intended to limit and / or restrict the invention.

[0038] Example 1

[0039] like Figures 1-6 As shown, the power tool in this embodiment mainly includes a housing 10 and a balancing structure disposed within the housing 10. The balancing structure mainly includes a drive module 20, a crank-connecting rod module 30, an output module 40, and two balancing mechanisms 50. The crank-connecting rod module 30 is used to convert the rotational motion of the drive module 20 into the linear motion of the output module 40. The output module 40 acts on the workpiece. The drive module 20 is a motor. The crank-connecting rod module 30 is conventionally composed of a crank 31 and a connecting rod 32 that are rotatably connected. It also includes a generally U-shaped guide frame 33, which restricts the linear reciprocating motion of the connecting rod 32 within it. The output module 40 is conventionally composed of a tool chuck and a tool, such as an electric reciprocating saw structure composed of a saw blade. Of course, it can also be a power tool with other functions, which will not be described in detail here.

[0040] The balancing mechanism 50 includes a transmission gear 51, a counterweight 52, and a connecting body 53. The drive module 20 drives the transmission gear 51 to rotate, and the counterweight 52 can rotate with the transmission gear 51. The two transmission gears 51 in the two balancing mechanisms 50 rotate in opposite directions, and the counterweight 52 is eccentrically positioned relative to the transmission gear 51.

[0041] Furthermore, the connecting body 53 is fixed inside the outer casing 10. The middle part of one side of the connecting body 53 protrudes outward to form a first shaft 531. A shaft hole 532 is provided through the first shaft 531 along its axial direction. The shaft hole 532 is for the second shaft 533 to pass through. The counterweight 52 is sleeved on the first shaft 531 and rotates around the first shaft 531. The second shaft 533 is connected to the center position of the transmission gear 51 and is coaxially arranged. Multiple bearings 58 are sleeved on the second shaft 533. The bearings 58 are arranged inside the outer casing 10 to facilitate the rotation of the second shaft 533 with the transmission gear 51 and reduce friction. Moreover, the center of the shaft hole 532 is eccentrically arranged relative to the center of the first shaft 531, that is, there is a gap between the centers of the two.

[0042] Here, the two transmission gears 51 are configured to rotate synchronously driven by the output shaft of the drive module 20. The two transmission gears 51 are located on both sides of the motion plane of the crank-connecting rod module 30, that is, the two transmission gears 51 directly mesh with the output shaft of the drive module 20 and drive the two counterweights 52 to rotate in opposite directions. A guide pin 501 is eccentrically provided on one side of one of the transmission gears 51. The crank-connecting rod module 30 is rotatably connected to the guide pin 501, thereby realizing the linear motion drive of the output module through the crank-connecting rod module 30.

[0043] Furthermore, a transmission body 511 is provided protruding on one side of the transmission gear 51, and a transmission groove 521 is provided recessed inward on one side of the counterweight 52. The transmission body 511 and the transmission groove 521 cooperate to form a sliding pair. Through the linear motion of the transmission body 511 in the transmission groove 521, the rotation of the transmission gear 51 in the eccentric state can drive the rotation of the counterweight 52.

[0044] Meanwhile, the balancing mechanism 50 is fixed within the fixed shell 60 to facilitate transplantation and assembly.

[0045] Example 2

[0046] like Figure 7As shown, the installation position of the balancing mechanism 50 has been changed. Assuming that it is a vertical up-down position in Embodiment 1, it is a horizontal left-right position in Embodiment 2. Here, the balancing mechanism 50 also includes a main gear 54, a transmission shaft 55, a secondary gear 56, and an intermediate gear 57. The main gear 54 and the secondary gear 56 are connected by the transmission shaft 55 and are coaxially arranged. The main gear 54 is configured to be driven to rotate by the output shaft of the drive module 20. One transmission gear 51 meshes with the secondary gear 56, and the other transmission gear 51 meshes with the intermediate gear 57. The intermediate gear 57 meshes with the secondary gear 56. The two transmission gears 51 are located on both sides of the transmission shaft 55 and drive the two counterweights 52 to rotate in opposite directions. A guide pin 2 is eccentrically arranged on one side of the main gear 54, and the crank connecting rod module 30 is rotatably connected to the guide pin 2.

[0047] Example 3

[0048] This embodiment provides a balancing method for the above-described balancing structure. First, refer to... Figure 8 The equations of motion and inertial forces of the equivalent block, as described by the equivalent centroid, are as follows:

[0049]

[0050] Where S is the displacement of the equivalent center of mass, L is the length of the connecting rod, R is the length of the crank, β is the angle between the connecting rod and the horizontal direction, and α is the angle between the curved edge and the horizontal direction.

[0051] Expanding the radical in the above formula using a Taylor series, since λ = R / L << 1, convergence is relatively fast. Considering taking the first two terms, we get:

[0052]

[0053] speed

[0054] acceleration

[0055] Directional force F s =Ma=MRω 2 (cosα+λcos2α);

[0056] The existing counterweight forms the balancing center of mass in the diagram, and the force it experiences is...

[0057] F c =m c eω 2

[0058] F cx =F c ·cosα

[0059] F cy =F c sinα;

[0060] The resultant force in the X and Y directions is

[0061] ΔF x =MRω0 2 ·(cosα+λcos2α)-m c eω 2 ·cosα

[0062] ΔF y =F c sinα-f≈m c eω 2 sinα;

[0063] The principle of this counterweight is to add a counterweight to the rotating joint and calculate the force of the counterweight in the reciprocating direction to counteract the output unbalanced force. The counterweight thus generates a force perpendicular to the reciprocating motion direction. Therefore, this scheme actually transfers the unbalanced force to other directions, and the effect of improving vibration is not obvious.

[0064] like Figure 9 As shown, In the diagram, the driving block is a transmission gear that rotates around point O, and the driven block is a counterweight that rotates around O'. Their equations of motion are as follows:

[0065] Rotation angle

[0066] Rotation speed

[0067] Rotational acceleration

[0068] To effectively balance the unbalanced force in the direction perpendicular to the motion (as shown in the Y direction), the balancing is divided into two parts and rotated in opposite directions around the axis of rotation. This allows the unbalanced force in the Y direction to be perfectly canceled out. Only the force in the X direction needs to be balanced, according to the weighting definition:

[0069] Let the equivalent mass of the counterweight be m and its equivalent radius be r, and let mr = x·MR;

[0070] The equivalent mass of the transmission gear is m1, and the equivalent radius is r1. Let m1r1 = y·MR;

[0071] Therefore, the equivalent resultant force equation in the X direction of the balanced structure is:

[0072]

[0073] Let k = r / e. Combining the weight settings of both, the equation can be transformed into the following balancing formula:

[0074]

[0075] Where M is the equivalent mass of output module 40, R is the crank length, k = r / e, r is the equivalent radius of counterweight 52, e is the distance between the rotation center of counterweight 52 and the rotation center of transmission gear 51, x is the balancing weight ratio of counterweight 52, y is the balancing weight ratio of transmission gear 51, and the boundary condition is min(x+y).

[0076] The balancing formula includes the following calculation process: Let ΣF=0, calculate the values ​​of x, y, and k, and take the values ​​of wt as 0° and 180°. Combining the weights x and y, the following equation is obtained:

[0077]

[0078] Obtain the values ​​of x, y, and k, and calculate them under the following conditions: m1r1 = y·MR; mr = x·MR; where m is the equivalent mass of the counterweight, m1 is the equivalent mass of the transmission gear 51, and r1 is the equivalent radius of the transmission gear 51; and based on the obtained r and the calculated k value, obtain the e value. Thus, obtain the corresponding data to set the balancing mechanism 50 to meet the balancing requirements.

[0079] The examples, embodiments, and particular forms of the invention illustrated have been shown and described in detail in the accompanying drawings and foregoing description, and should also be considered illustrative rather than restrictive. The description of a particular feature in one embodiment does not imply that those particular features must be limited to that one embodiment. Features of one embodiment can be used in combination with features of other embodiments, as will be understood by those skilled in the art, whether or not explicitly stated. Exemplary embodiments have been shown and described, and all variations and modifications fall within the spirit of the invention and are intended to be protected.

Claims

1. A balancing structure for a power tool, comprising a drive module (20), a crank-connecting rod module (30), and an output module (40), wherein the crank-connecting rod module (30) is used to convert the rotational motion of the drive module (20) into the linear motion of the output module (40), and the output module (40) acts on a workpiece, characterized in that, It also includes two opposing balancing mechanisms (50), each balancing mechanism (50) including a transmission gear (51) and a counterweight (52). The drive module (20) drives the transmission gear (51) to rotate, and the counterweight (52) can rotate with the transmission gear (51). The two transmission gears (51) in the two balancing mechanisms (50) rotate in opposite directions, and the counterweight (52) is eccentrically positioned relative to the transmission gear (51). The balancing mechanism (50) also includes a connecting body (53), one side of which protrudes outward and forms a first shaft (531). The first shaft (531) contains... A shaft hole (532) is provided through it along its axial direction. The shaft hole (532) is for the second shaft body (533) to pass through. The counterweight (52) is sleeved on the first shaft body (531) and rotates around the first shaft body (531). The second shaft body (533) is connected to the transmission gear (51) and is coaxially arranged. The shaft hole (532) is eccentrically arranged relative to the first shaft body (531). A transmission body (511) is provided protruding on one side of the transmission gear (51), and a transmission groove (521) is provided recessed inward on one side of the counterweight (52). The transmission body (511) and the transmission groove (521) cooperate to form a sliding pair.

2. The balancing structure of a power tool according to claim 1, characterized in that, The two transmission gears (51) are configured to rotate synchronously driven by the output shaft of the drive module (20). The two transmission gears (51) are located on both sides of the motion plane of the crank connecting rod module (30) and drive the two counterweights (52) to rotate in opposite directions.

3. The balancing structure of a power tool according to claim 1, characterized in that, The balancing mechanism (50) also includes a main gear (54), a transmission shaft (55), a secondary gear (56), and an intermediate gear (57). The main gear (54) and the secondary gear (56) are connected and coaxially arranged through the transmission shaft (55). The main gear (54) is configured to be driven to rotate by the output shaft of the drive module (20). One transmission gear (51) meshes with the secondary gear (56), and the other transmission gear (51) meshes with the intermediate gear (57). The intermediate gear (57) meshes with the secondary gear (56). The two transmission gears (51) are located on both sides of the transmission shaft (55) and drive the two counterweights (52) to rotate in opposite directions.

4. The balancing structure of a power tool according to claim 2, characterized in that, A guide pin (501) is eccentrically disposed on one side of one of the transmission gears (51), and the crank connecting rod module (30) is rotatably connected to the guide pin (501).

5. The balancing structure of a power tool according to claim 3, characterized in that, A guide pin 2 (502) is eccentrically provided on one side of the main gear (54), and the crank connecting rod module (30) is rotatably connected to the guide pin 2 (502).

6. A power tool, comprising the balancing structure of a power tool as described in any one of claims 1-5.

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