Sander and airflow chip removal device suitable for electric power tools

Abstract

This invention discloses a sander and an airflow chip removal device suitable for power tools. The sander includes an airflow element capable of rotating around a central axis in a preset direction to generate a chip removal airflow. The sander also includes a housing configured to house the airflow element and guide the chip removal airflow generated by the airflow element. The inner wall of the housing forms a guide wall, and the distance from the guide wall to the central axis is defined as a first distance D1, which gradually increases along the preset direction. This sander has low dust suction resistance and a long operating time.

Description

Technical Field

[0001] This invention relates to a power tool, specifically to a sander and an airflow chip removal device suitable for power tools. Background Technology

[0002] A sander is a power tool used for sanding operations. It is commonly used to sand uneven or varying thickness surfaces such as walls and tabletops to achieve a desired smoothness. Sanders are also known as belt sanders, wheel sanders, or polishing machines. Handheld sanders are an important category of sanders, widely used in various industries due to their compact size and portability.

[0003] Sanders generate dust during sanding operations. The dust can be drawn into the sander's casing and discharged in a specific direction. Therefore, the lower the suction resistance, the higher the dust collection efficiency of the sander. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a sander with low suction resistance and long runtime.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A sander includes: an airflow element capable of rotating about a central axis in a preset direction to generate a chip-exhausting airflow; the sander also includes: a housing configured to house the airflow element and guide the chip-exhausting airflow generated by the airflow element; wherein, the inner wall of the housing is formed with a guide wall, the distance from the guide wall to the central axis is defined as a first distance D1, and the first distance D1 gradually increases along the preset direction.

[0007] Furthermore, the sander also includes: a motor, which provides power to the airflow components; a battery pack, which provides energy to the motor; when the sander is in an unloaded state, the working time of the sander under the condition that the battery pack consumes 10WH of energy is defined as the functional time T of the sander; the product of the motor's unloaded speed N and the sander's power supply time T is greater than or equal to 63000 rpm.min and less than or equal to 120000 rpm.min.

[0008] Furthermore, the sander also includes: a motor, used to provide power to the airflow element; a battery pack, used to provide energy to the motor; when the sander is in an unloaded state, the working time of the sander under the condition that the battery pack consumes 10WH of energy is defined as the functional time T of the sander; the product of the motor's unloaded speed N and the sander's power supply time T is greater than or equal to 77000rpm.min and less than or equal to 110000rpm.min.

[0009] Furthermore, the farthest point of the airflow element from the central axis forms a circle as the airflow element rotates around the central axis in a preset direction; the distance from the guide wall to the circle is defined as the second distance D2, and the second distance D2 gradually increases along the preset direction.

[0010] Furthermore, the inner wall includes at least one structural segment that satisfies the Archimedes spiral equation along a plane perpendicular to the central axis.

[0011] Furthermore, the airflow element is a centrifugal fan.

[0012] Furthermore, the centrifugal fan includes: a chassis that can rotate around a central axis; multiple fan blades that are fixedly connected to the chassis or integrally formed; the fan blades extend along a curve, the direction of the curve being opposite to the preset rotation direction of the centrifugal fan.

[0013] Furthermore, the housing is provided with an air outlet for chip removal and air exhaust; the ratio of the distance of the air outlet on the plane perpendicular to the central axis to the radius of the centrifugal fan is greater than or equal to 1 and less than or equal to 1.5.

[0014] Furthermore, the product of the centrifugal fan's weight and the square of its outer diameter is greater than or equal to 3000 g / mm. 2 Less than or equal to 10000 g.mm 2 .

[0015] Furthermore, the centrifugal fan includes: a chassis capable of rotating around a central axis; multiple fan blades fixedly connected to the chassis or integrally formed therewith; each fan blade is defined with a first fan blade surface and a second fan blade surface, wherein the first fan blade surface is located in front of the second fan blade surface along a preset rotation direction; the opposite ends of the first fan blade surface and the second fan blade surface respectively converge to form a front edge and a rear edge, wherein the front edge is farther away from the central axis from the rear edge; and the outer edge of the chassis is at least partially in contact with the front edge.

[0016] Furthermore, the sander also includes: a motor for providing power to the airflow element, the motor driving a centrifugal fan to rotate around a central axis; an eccentric element driven by the motor, the eccentric element having an axis offset from the central axis; and a base plate that can be driven by the motor. A coordinate system is established with a point on the central axis as its origin, the direction of the line connecting the central axis and the axis is defined as the X-axis, and the direction perpendicular to the line connecting the central axis and the axis is defined as the Y-axis. The projection of the first fan blade surface onto the plane formed by the X-axis and Y-axis is defined as the first projection line, and the tangent line of the first projection line furthest from the central axis is defined as the first tangent line. The tangent line at the intersection of the outer edge of the base plate and the first projection line within the plane formed by the X-axis and Y-axis is defined as the second tangent line. The angle between the first tangent line and the second tangent line is greater than or equal to 20 degrees and less than or equal to 45 degrees.

[0017] Furthermore, in the plane formed by the X-axis and Y-axis, the endpoint of the first projection line near the outer edge of the chassis is defined as A, and the endpoint of the first projection line near the central axis is defined as B. The ratio of the radius of the centrifugal fan to the distance L1 between the endpoints A and B of the first projection line is greater than or equal to 4 and less than or equal to 7.5.

[0018] Furthermore, the fan blades are positioned on the side closest to the base plate.

[0019] Furthermore, the weight of the centrifugal fan is less than or equal to 100g.

[0020] An airflow chip removal device suitable for power tools includes: an airflow element capable of rotating around a central axis in a preset direction to generate a chip removal airflow; a motor for providing a power source to the airflow element; and a battery pack for providing an energy source to the motor. The airflow chip removal device further includes: a chip removal housing configured to house the airflow element and guide the chip removal airflow generated by the airflow element; wherein the inner wall of the chip removal housing has a guide wall, the distance from the guide wall to the central axis is defined as a first distance D1, and the first distance D1 gradually increases along the preset direction; when the motor is in an unloaded state, the operating time of the chip removal device under 10Wh of energy consumption from the battery pack is defined as the power supply time T of the chip removal device; the product of the motor's unloaded speed N and the power supply time T of the chip removal device is greater than or equal to 77000 rpm·min and less than or equal to 110000 rpm·min.

[0021] Furthermore, the inner wall includes at least one structural segment that satisfies the Archimedes spiral equation along a plane perpendicular to the central axis.

[0022] Furthermore, the airflow element is a backward-curved centrifugal fan.

[0023] The advantage of this invention is that it provides a sander with low suction resistance and long battery life. Attached Figure Description

[0024] Figure 1 This is a perspective view of the sander used in this application;

[0025] Figure 2 yes Figure 1 The image shown is a 3D view of the sander with part of the casing removed.

[0026] Figure 3 yes Figure 1 The diagram shows a plan view of the entire sander.

[0027] Figure 4 yes Figure 3 The sander shown is a cross-sectional view along the AA direction;

[0028] Figure 5 yes Figure 3 The sander shown is a cross-sectional view along the BB direction;

[0029] Figure 6 yes Figure 5 A partially enlarged view of the cross-sectional view of the sander shown;

[0030] Figure 7 This is a simplified schematic diagram of the cross-section of an airflow element and a chip removal housing structure in this application;

[0031] Figure 8 This is a simplified schematic diagram of another cross-section of the airflow element and chip removal housing structure in this application;

[0032] Figure 9 yes Figure 1 A 3D view of the centrifugal fan in the sander shown;

[0033] Figure 10 yes Figure 9 A three-dimensional view of the centrifugal fan from another perspective;

[0034] Figure 11 yes Figure 9 The plan view of the centrifugal fan is shown.

[0035] Figure 12 yes Figure 11 A partially enlarged view of the centrifugal fan shown. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0037] Figure 1 The image shows a sander 100 equipped with a chip removal device 10. This device drives a functional element, which can be sandpaper, to perform sanding, polishing, and other finishing operations on the surfaces of workpieces made of various materials. During the grinding process, the sander 100 generates a large amount of chips, which are drawn into the chip removal device 10. The chip removal device 10 then discharges the chips to a preset location. A dust collection device can be installed at this location to collect the chips discharged from the chip removal device 10, thus achieving a dust collection effect. Therefore, it is essential to install an airflow chip removal device 10 on the sander 100. It should also be noted that the chip removal device 10 is not only used on the sander 100, but can also be used on other power tools that require dust collection and / or chip removal. Furthermore, the chip removal device 10 can be integrated with the power tool or can be separate from the power tool, that is, the power tool and the chip removal device 10 are two separate machines that work together during operation to achieve the function of dust collection and / or chip removal.

[0038] The following description will use a sander 100 as an example. For ease of description, definitions will be provided as follows: Figure 1 The directions shown are up, down, left, right, front, and back.

[0039] like Figures 1 to 6 As shown, the sander 100 includes: a housing 20, a switch assembly 30, a base plate assembly 40, a power assembly 50, a chip removal device 10, an eccentric element 60, and an energy source 70.

[0040] The housing 20 forms the outer shape of the sander 100, and includes at least a handle 21, a receiving portion 22, and a support portion 23. The handle 21 is for the user to grip; one end of the handle 21 connects to the receiving portion 22, and the other end can be used to connect an external power cable or form a connector for mounting a portable DC power supply such as a battery pack. The receiving portion 22 is located between the handle 21 and the support portion 23, and an internal cavity is formed within the receiving portion 22, where at least a portion of the power assembly 50 is disposed. The support portion 23 covers the chip removal device 10 and at least a portion of the base plate assembly 40.

[0041] The switch assembly 30 can be mounted on the housing 20. Specifically, the switch assembly 30 is mounted on the handle 21. This arrangement allows the user to easily trigger the switch assembly 30 when holding the handle 21.

[0042] The power assembly 50 can be driven by the switch assembly 30. The power assembly 50 includes a motor 51, which serves as the prime mover of the sander 100 and is housed within the housing 20. The motor 51 includes a motor shaft 52 for outputting power, which rotates about a motor axis 101. In this embodiment, the motor axis 101 extends substantially in the vertical direction.

[0043] The chip removal device 10 includes an airflow element 11 that can be driven by a motor 51. That is, the airflow element 11 can be driven by the motor 51 to rotate around the central axis 102. When the airflow element 11 rotates, it can generate an airflow for chip removal. In this embodiment, the central axis 102 extends substantially in the vertical direction.

[0044] An eccentric element 60 surrounds the motor shaft 52 and is eccentrically positioned relative to the motor shaft 52. The eccentric element 60 is mounted on and fixedly connected to the motor shaft 52. It should be noted that the eccentric positioning of the eccentric element 60 relative to the motor shaft 52 means that the eccentric element 60 has an axis parallel to the motor shaft axis 101 of the motor shaft 52, with a distance d between them. The existence of distance d allows the eccentric element 60 to transmit the rotation of the motor shaft 52 into the rotation and revolution of other components connected to the eccentric element 60 when the motor shaft 52 rotates. In this embodiment, the axis of the eccentric element 60 substantially coincides with the central axis 102.

[0045] The motor shaft 52 drives the base plate assembly 40, enabling the base plate assembly 40 to swing relative to the housing 20. Specifically, the base plate assembly 40 is fixedly connected to the eccentric element 60, meaning that the motor shaft 52 transmits power to the base plate assembly 40 through the eccentric element 60. The base plate assembly 40 includes a base plate with through holes, comprising an upper surface and a lower surface opposite to each other, with the through holes penetrating both surfaces. The lower surface is positioned relative to the upper surface on the side furthest from the eccentric element 60, and is used to mount functional components such as sandpaper. Several through holes are provided on the lower surface. Driven by the motor shaft 52 and the eccentric element 60, the base plate can perform eccentric motion. When the base plate performs eccentric motion, the sandpaper continuously rubs against the surface of the workpiece to be ground, thereby achieving functions such as grinding and polishing.

[0046] The energy source 70 is used to provide energy to the sander 100. The energy source 70 can be AC ​​power or DC power, such as a portable power source like a battery pack.

[0047] The chip removal device 10 also includes a chip removal housing 12, which is fixedly connected to or integrally formed with the housing 20. The chip removal housing 12 is configured to accommodate the airflow element 11, that is, the inner wall of the chip removal housing 12 forms a first space 110 for accommodating the airflow element 11. The inner wall of the chip removal housing 12 also forms a guide channel 13 for guiding the chip removal airflow. In this embodiment, the housing 20 forms the aforementioned chip removal housing 12. Specifically, when the sander 100 is started, the motor shaft 52 drives the airflow element 11 to rotate around the central axis 102 in a preset rotation direction 103. During the rotation, the airflow element 11 generates negative pressure, drawing air from its lower surface into the first space 110 through the through hole. At this time, the rotating airflow element 11 throws the drawn-in airflow out along the outer periphery of the airflow element 11. As the airflow flows, it draws the debris generated during the sandpaper grinding process into the first space 110 through the through hole. The guide channel 13 formed by the chip removal housing 12 guides the flow of the airflow carrying debris and directs the airflow to a preset position. An air outlet 14 is provided at a preset position to discharge airflow containing debris from the first space 110. It should be noted that in the embodiment where the chip removal device 10 is separated from the power tool, the chip removal housing 12 of the chip removal device 10 is separated from the housing 20. It should be explained that the preset rotation direction 103 refers to the direction of rotation of the airflow element 11 when the motor 51 drives it to rotate. For clarity in describing the technical solution, the preset rotation direction 103 is defined as follows: Figure 1 The first direction a is shown.

[0048] Furthermore, the chip removal housing 12 includes a first housing portion 121 and a second housing portion 122. The first housing portion 121 and the second housing portion 122 are detachably and fixedly connected, that is, the first space 110 is formed by the fixed connection of the first housing portion 121 and the second housing portion 122. Because the sander 100 will generate strong vibrations during operation, in order to ensure the stability of the connection between the first housing portion 121 and the second housing portion 122, the first housing portion 121 and the second housing portion 122 can be fixedly connected by a fastener 123. The fastener 123 for fixing is located outside the first space 110, that is, the fastener 123 is not located inside the guide channel 13. This arrangement can avoid the fastener 123 being located inside the guide channel 13, which would affect the flow of the chip removal airflow, thereby increasing the dust suction resistance of the sander 100 and affecting the dust suction effect.

[0049] The inner wall of the chip removal housing 12 has a guide wall 124 for guiding the flow of chip removal airflow, and an upper side wall 125 and a lower side wall 126 arranged opposite to each other along the central axis 102. The guide wall 124 is disposed between the upper side wall 125 and the lower side wall 126, and the guide wall 124 connects the upper side wall 125 and the lower side wall 126. The guide wall 124 is disposed in the circumferential direction of the airflow element 11. The guide wall 124, the upper side wall 125, and the lower side wall 126 substantially form the aforementioned guide channel 13. When the airflow element 11 rotates about the central axis 102, it has a plane of rotation P. The upper side wall 125 is located in the aforementioned plane of rotation P, and the central axis 102 is perpendicular to the plane of rotation P. It should be noted that the guide wall 124, upper side wall 125 and lower side wall 126 referred to in this application form the above-mentioned guide channel 13. This is not strictly limited to the guide channel 13 being composed only of the guide wall 124, upper side wall 125 and lower side wall 126. Rather, it is permissible for parts of the guide channel 13 to be formed by other components. However, the guide part of the guide channel 13 that mainly guides the airflow of the chip discharge is composed of the guide wall 124, upper side wall 125 and lower side wall 126.

[0050] In the direction perpendicular to the central axis 102, the distance from the guide wall 124 to the central axis 102 is defined as the first distance D1. The first distance D1 gradually increases along a preset rotation direction 103. That is, along the preset rotation direction 103, the distance between the guide wall 124 and the central axis 102 gradually increases, meaning the guide channel 13 gradually increases along the preset rotation direction 103. In other words, along the direction of the rotation plane P, the width of the upper side wall 125 gradually increases along the preset rotation direction 103. This arrangement reduces the dust suction resistance when the chip exhaust airflow flows along the guide channel 13, improving dust suction performance, reducing the energy consumption of the sander 100 during operation, and thus extending the working time of the sander 100. It should be noted that the gradual increase here refers to an increase according to a certain rule, which can be a linear or non-linear rule.

[0051] The airflow element 11 has a farthest end 111, which refers to the end of the airflow element 11 furthest from the central axis 102 in the direction of the rotation plane P. Under normal conditions, the farthest end 111 of the airflow element 11 will form a circle as it rotates around the central axis 102 along a predetermined rotation direction 103. The distance from the guide wall 124 to this circle is defined as a second distance D2, which gradually increases along the predetermined rotation direction 103 in the direction of the rotation plane P. It should be noted that the airflow element 11 is not necessarily regular; that is, there must be at least one farthest end 111. As one embodiment, the outer periphery of the airflow element 11 is approximately triangular (e.g., ...). Figure 8 As shown), in another embodiment, the outer periphery of the airflow element 11 is approximately rectangular (e.g., as shown). Figure 7 As shown in the figure, in some other embodiments, the outer periphery of the airflow element 11 is approximately polygonal. In this embodiment, the outer periphery of the airflow element 11 is approximately circular, that is, the distance from the outer periphery of the airflow element 11 to the central axis 102 is basically the same in the direction along the rotation plane P. In other words, it can be understood that the radius of the circle formed by the airflow element 11 during rotation along the preset rotation direction 103 is basically the same as the radius of the circle formed by the outer periphery of the airflow element 11. That is to say, the distance from the inner wall of the chip discharge housing 12 to the outer periphery of the airflow element 11 gradually increases along the preset rotation direction 103. In this embodiment, the airflow element 11 is specifically a centrifugal fan 15.

[0052] An air outlet 14 is formed on the first housing portion 121 or the second housing portion 122. The air outlet 14 is used to discharge the airflow in the guide channel 13 into the first space 110, and the air outlet 14 is formed by the guide wall 124 and the upper side wall 125. In the direction along the plane of rotation P, the ratio of the width of the air outlet 14 to the radius of the airflow element 11 is greater than or equal to 1 and less than or equal to 1.5. Under the condition that other conditions remain unchanged, the larger the radius of the airflow element 11, the greater the air volume of the generated chip removal airflow, thereby improving the dust collection efficiency of the sander 100. That is, in the same unit of time, the larger the radius of the airflow element 11, the higher the dust collection efficiency of the sander 100. Similarly, under the same conditions, the larger the width of the air outlet 14, the greater the air volume discharged at the same time. Therefore, the larger the width of the air outlet 14, the higher the dust collection efficiency of the sander 100. By setting the width of the air outlet 14 and the radius of the airflow element 11 within the above range, it is convenient for the chip removal airflow in the first space 110 to be discharged. Furthermore, in this embodiment, the width of the air outlet 14 along the plane of rotation P is greater than or equal to 40 mm and less than or equal to 65 mm. It should be noted that the width of the air outlet 14 refers to the farthest distance between the sidewalls forming the air outlet 14 in the direction along the plane of rotation P and perpendicular to the central axis 102 (i.e., as shown in the figure). Figure 4 (L shown). Further, the ratio of the width of the air outlet 14 to the radius of the airflow element 11 is greater than or equal to 1.1 and less than or equal to 1.3. Setting the ratio of the width of the air outlet 14 to the radius of the airflow element 11 within the above range can ensure that the dust collection efficiency of the sander 100 is high, while also ensuring that the projected area of ​​the guide channel 13 of the sander 100 on the rotating plane P is not too large, thus making the overall size of the sander 100 too large and inconvenient to operate.

[0053] Along the direction of the plane of rotation P, the inner wall of the chip removal housing 12 includes at least one structural segment 127 that satisfies the Archimedes' spiral equation. That is, the inner wall of the guide channel 13 has at least one section whose extension direction satisfies the Archimedes' spiral equation. In other words, the interior of the guide channel 13 can be formed by multiple structural segments 127 that satisfy different rules connected together (e.g., ...). Figure 7 , Figure 8 As shown in the figure, the different laws can be linear or nonlinear, or multiple structural segments 127 can simultaneously include linear and nonlinear laws. Furthermore, for ease of design and manufacturing, the inner wall of the guide channel 13 extends in the form of an Archimedean spiral, with its extension direction satisfying the Archimedean spiral equation. In this embodiment, the two ends of the inner wall forming the air outlet 14 are defined as the first end 141 and the second end 142. The guide wall 124 connecting the first end 141 and the second end 142 extends in a direction that satisfies the polar coordinate equation of the Archimedean spiral, which is R = a + bθ. In other words, the first end 141 can be approximated as the starting point of the Archimedean spiral, and the second end 142 can be approximated as the ending point of the Archimedean spiral. That is, the inner wall of the chip removal housing 12 increases equidistantly from the first end 141 along a preset spiral direction 103. Furthermore, the distance from the central axis 102 to the first end 141 is greater than or equal to 40 mm and less than or equal to 60 mm. The increase in the inner wall along the preset rotation direction 103 by a unit angle is greater than 1.3 mm and less than 1.8 mm, i.e., a is greater than or equal to 40 mm and less than or equal to 60 mm, and b is greater than 1.3 mm and less than 1.8 mm. It should be noted that the width of the air outlet 14 can also be described as the distance L between the first end 141 and the second end 142. Furthermore, in the direction along the rotation plane P, the distance D from the fixing member 123 to the central axis 102 is greater than a + bθ. That is, the fixing member 123 is located outside the guide channel 13 enclosed by the polar coordinate equation of the Archimedean spiral; that is, the mounting position for fixing is also located outside the guide channel 13. This arrangement avoids the mounting position affecting the extension direction of the guide wall 124, thus preventing the mounting position from affecting the airflow guidance.

[0054] When the sander 100 is in an unloaded state, the working time of the sander 100 when the battery pack consumes 10Wh of energy is defined as the functional time T of the sander 100. The product of the no-load speed N of the motor 51 and the functional time T of the sander 100 is greater than or equal to 63,000 rpm·min and less than or equal to 120,000 rpm·min. In one embodiment, the product of the no-load speed N of the motor 51 and the functional time T of the sander 100 is greater than or equal to 70,000 rpm·min and less than or equal to 115,000 rpm·min. In other embodiments, the product of the no-load speed N of the motor 51 and the functional time T of the sander 100 is greater than or equal to 77,000 rpm·min and less than or equal to 110,000 rpm·min. In this embodiment, the functional time T of the sander 100 is greater than or equal to 7 min and less than or equal to 11 min.

[0055] like Figures 5 to 6 As shown, the sander 100 also includes a balance block 80. The balance block 80 is used to achieve dual balance of mass and torque of the base plate. Along the central axis 102, the balance block 80 is located between the centrifugal fan 15 and the base plate. The balance block 80 and the eccentric element 60 are detachably fixedly connected, meaning that the eccentric element 60 and the balance block 80 move synchronously, and the balance block 80 can rotate around the axis with the eccentric element 60. The balance block 80 and the centrifugal fan 15 are two separate components. Positioning the balance block 80 below the centrifugal fan 15 can be understood as placing the center of mass of the balance block 80 closer to the base plate, reducing the distance between the center of mass of the balance block 80 and the base plate, thus reducing the torque between them. This reduces the weight of the balance block 80 used to balance the torque. We can also understand this as eliminating the need for other weight blocks to balance the torque, thus avoiding the need to add weight to the balance block 80 to balance other weight blocks. Alternatively, simply adding other very light weight blocks can offset the torque. This would require adding an extra weight block of the same weight as the other weight blocks to the balance block 80. Thus, we can see that by setting it up as described above, the weight of the balance block 80 can be significantly reduced, thereby reducing the weight of the sander 100. This makes it easier for users to operate, reduces the overall weight of the machine, reduces user fatigue, and also reduces the energy consumption of the sander 100.

[0056] In this embodiment, the eccentric element 60 is integrally formed with the centrifugal fan 15, meaning the eccentric element 60 is formed on the centrifugal fan 15. The centrifugal fan 15 is mounted on the motor shaft 52 and can be driven by the motor shaft 52 to rotate. Alternatively, the centrifugal fan 15 can be considered the eccentric element 60. Specifically, the centrifugal fan 15 uses a material with a density less than 6.5 g / cm³. Since weight is directly proportional to density, the lower the density, the lighter the centrifugal fan 15, effectively reducing its weight and thus the weight of the sander 100. Preferably, when the centrifugal fan 15 uses a material with a density greater than or equal to 1 g / cm³ and less than or equal to 3 g / cm³, it satisfies structural strength requirements while reducing the weight of the centrifugal fan 15. Furthermore, the centrifugal fan 15 can be made of aluminum, which reduces its weight and saves costs.

[0057] It is important to note that when the motor 51 drives the centrifugal fan 15 to rotate, the centrifugal fan 15 generates rotational inertia. This means that the rotation of the centrifugal fan 15 creates a constraint force that keeps it rotating around the motor axis 101. This constraint force will restrain the sander 100 from continuing to rotate in the vertical direction when it tends to move in a direction intersecting the vertical direction. In other words, when the user applies a force to the sander 100 to move it in a direction intersecting the vertical direction, the constraint force will cause the sander 100 to tend to move in the opposite direction. This requires the user to apply more force to overcome the constraint force, resulting in operational inconvenience. Furthermore, prolonged operation in this manner can easily cause user fatigue and affect work efficiency. The rotational inertia is directly proportional to the weight of the centrifugal fan 15. The greater the weight of the centrifugal fan 15, the greater the rotational inertia, and the greater the impact on the user. Therefore, the above-mentioned settings can reduce the rotational inertia, thereby improving the user experience.

[0058] Furthermore, the ratio of the product of the weight of the centrifugal fan 15 and the square of its outer diameter is greater than or equal to 3000 g / mm. 2 Less than or equal to 10000 g.mm 2 The outer diameter refers to the radius of the outer edge 159 of the centrifugal fan 15. By setting the ratio of the weight of the centrifugal fan 15 to the square of the outer diameter within the above range, the rotational inertia generated by the centrifugal fan 15 during rotation can be effectively reduced, the influence of constraint forces during user operation can be reduced, and thus the work efficiency can be improved.

[0059] Furthermore, the total weight of the centrifugal fan 15 and the motor 51 is less than or equal to 400g. Within the internal structure of the sander 100, the motor 51 and centrifugal fan 15 are relatively heavy compared to other components; that is, the weight of the sander 100 is mainly concentrated in the motor 51 and centrifugal fan 15. By adjusting the structure and position of the balance block 80 and the centrifugal fan 15, the weight of the centrifugal fan 15 is significantly reduced, resulting in a sander 100 with a smaller moment of inertia and lighter weight. This also reduces the energy consumption of the sander 100 and extends its working time. In some embodiments, the weight of the centrifugal fan 15 is less than or equal to 100g; in some other embodiments, the weight of the centrifugal fan 15 is less than or equal to 80g; and in still other embodiments, the weight of the centrifugal fan 15 is less than or equal to 60g.

[0060] like Figures 9-12 As shown, the centrifugal fan 15 is specifically a backward-curved type. The centrifugal fan 15 includes a chassis 151 and multiple fan blades 152 that are substantially perpendicular to the surface of the chassis 151. Along the central axis 102, the fan blades 152 are positioned below the chassis 151, near the base plate. The chassis 151 is rotatable around the central axis 102. The chassis 151 is connected to the motor shaft 52 of the motor 51, and the motor shaft 52 can drive the chassis 151 to rotate. The multiple fan blades 152 are evenly distributed around the central axis 102. Furthermore, the fan blades 152 extend outward from the central axis 102, and along the central axis 102, the fan blades 152 extend from the chassis 151 towards the base plate. The multiple fan blades 152 are fixedly connected to the chassis 151 or integrally formed. In this embodiment, the multiple fan blades 152 and the chassis 151 are integrally formed as a single part. The fan blade 152 extends along a curve, wherein the direction of the curve is opposite to the preset rotation direction 103 of the centrifugal fan 15, that is, the fan blade 152 extends along a second direction opposite to the first direction. It should be noted that the centrifugal fan 15 includes at least three or more fan blades 152.

[0061] Each fan blade 152 has a concave surface recessed towards the interior of the fan blade 152 and a convex surface protruding towards the exterior of the fan blade 152. Each fan blade 152 has a first fan blade surface 153 and a second fan blade surface 154. The first fan blade surface 153 corresponds to the convex surface, and the second fan blade surface 154 corresponds to the concave surface. The first fan blade surface 153 and the second fan blade surface 154 are substantially perpendicular to the plane of rotation P. In the preset rotation direction 103, the first fan blade surface 153 is located in front of the second fan blade surface 154. The first fan blade surface 153 and the second fan blade surface 154 form opposing front edges 155 and rear edges 156. In the direction along the plane of rotation P, the front edge 155 is farther away from the central axis 102 relative to the rear edge 156, that is, the rear edge 156 is closer to the central axis. The distance from the front edge 155 to the central axis 102 is equal to the distance from the outer edge 159 of the base plate to the central axis 102. In this embodiment, it can be understood that the front edge 155 is at least partially in contact with the outer edge 159 of the chassis 151. It should be noted that "equal" here is not strictly limited to the distance from the front edge 155 to the central axis 102 being exactly equal to the distance from the outer edge 159 of the chassis 151 to the central axis. Rather, it can be understood as the distance from the front edge 155 to the central axis 102 being equal to the distance from the outer edge 159 of the base plate to the central axis 102, as long as it is within the allowable error range. Of course, in other embodiments, we do not completely limit the front edge 155 to contact with the outer edge 159 of the chassis 151. The front edge 155 may not contact the outer edge 159 of the chassis 151, that is, the distance from the front edge 155 to the central axis 102 may be less than the distance from the outer edge 159 of the base plate to the central axis 102. Of course, in other instances, the distance from the front edge 155 to the central axis 102 is greater than the distance from the outer edge 159 of the chassis 151 to the central axis 102, that is, the fan blade 152 protrudes from the chassis 151 in the axial direction along the chassis 151.

[0062] To further illustrate the specific structure of the centrifugal fan 15, a coordinate system is established here with a point on the central axis 102 as the origin. The direction connecting the central axis 102 to the axis is defined as the X-axis, and the direction perpendicular to the line connecting the central axis 102 to the axis is defined as the Y-axis. The projection of the first blade surface 153 of the fan blade 152 onto the plane formed by the X-axis and the Y-axis is defined as the first projection line 157, and the projection of the second blade surface 154 of the fan blade 152 onto the plane formed by the X-axis and the Y-axis is defined as the second projection line 158. Both the first projection line 157 and the second projection line 158 are arcs in the plane formed by the X-axis and the Y-axis. Specifically, the first projection line 157 can be a smooth arc segment or formed by connecting several smooth arc segments, with a relatively uniform curvature transition between the arc segments. Similarly, the second projection line 158 can be a smooth arc segment or formed by connecting several smooth arc segments, with a smooth connection between the arc segments. It should be noted that the curvature of the first projection line 157 and the second projection line 158 is not limited here; that is, the formation methods of the first projection line 157 and the second projection line 158 can be the same or different. The above settings make the curvature transition of the first fan blade surface 153 and the second fan blade surface 154 relatively uniform and smooth overall. During the rotation of the chassis 151, the resistance encountered by the airflow passing over the fan blade section 152 is greatly reduced, which increases the air volume of the centrifugal fan 15 during rotation and also reduces the noise during operation.

[0063] The tangent line of the first projection line 157 furthest from the central axis 102 is defined as the first tangent line 1571, and the tangent line at the intersection of the outer edge 159 of the chassis 151 and the first projection line 157 is defined as the second tangent line 1581. The angle α between the first tangent line 1571 and the second tangent line 1581 is greater than or equal to 20 degrees and less than or equal to 45 degrees. Setting the angle between the first tangent line 1571 and the second tangent line 1581 within the above range can significantly optimize the airflow and noise suppression effect of the centrifugal fan 15. In other words, setting the angle within the above range can further optimize the dust collection effect of the sander 100, while also reducing noise and improving the user experience. Furthermore, an angle α between the first tangent line 1571 and the second tangent line 1581 greater than or equal to 30 degrees and less than or equal to 40 degrees can further enhance the above effects. In the plane formed by the X and Y axes, the endpoint of the first projection line 157 near the outer edge 159 of the chassis 151 is defined as A, and the endpoint of the first projection line 157 near the central axis 102 is defined as B. Similarly, the endpoint of the second projection line 158 near the outer edge 159 of the chassis 151 is defined as C, and the endpoint of the second projection line 158 near the central axis 102 is defined as D. In this application, the first projection line 157 and the second projection line 158 are basically parallel, that is, the distance L1 between endpoints A and B of the first projection line 157 is basically equal to the distance L2 between endpoints C and D of the second projection line 158. The ratio of the radius of the centrifugal fan 15 to the distance L1 between endpoints A and B of the first projection line 157 is greater than or equal to 4 and less than or equal to 7.5. Setting the ratio within the above range allows the centrifugal fan 15 to achieve sufficient dust extraction while reducing its weight, thereby further reducing the overall energy consumption of the machine and extending the working time of the sander 100. Furthermore, the ratio of the radius of the centrifugal fan 15 to the distance between endpoints A and B of the first projection line 157 is greater than or equal to 4.5 and less than or equal to 6.5, which yields even better results. The distance L1 between endpoints A and B of the first projection line 157 is greater than or equal to 5 mm and less than or equal to 11 mm.

[0064] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A sander, comprising: The airflow element is capable of rotating around its central axis in a preset direction to generate a chip removal airflow. Its features are: The sander also includes: The housing is configured to house the airflow element and guide the chip removal airflow generated by the airflow element; The inner wall of the housing is formed with a guide wall, and the distance from the guide wall to the central axis is defined as a first distance D1, which gradually increases along the preset direction of rotation. The airflow element is a centrifugal fan; The housing is provided with an air outlet for chip removal and ventilation; The ratio of the distance of the air outlet along a plane perpendicular to the central axis to the radius of the centrifugal fan is greater than or equal to 1 and less than or equal to 1.

5. The centrifugal fan includes a chassis and multiple fan blades, the fan blades being substantially perpendicular to the chassis, and each fan blade having a first fan blade surface and a second fan blade surface. The sander further includes: an eccentric element driven by a motor, the eccentric element having an axis offset from the central axis; A coordinate system is established with a point on the central axis as the origin, the direction of the line connecting the central axis to the axis is the X-axis, and the direction perpendicular to the line connecting the central axis to the axis is the Y-axis. The projection of the first wind blade surface onto the plane formed by the X-axis and the Y-axis is defined as the first projection line, and the projection of the second wind blade surface onto the plane formed by the X-axis and the Y-axis is defined as the second projection line. Both the first projection line and the second projection line are arcs in the plane formed by the X-axis and the Y-axis. In the plane formed by the X-axis and Y-axis, the endpoint of the first projection line near the outer edge of the chassis is defined as A, and the endpoint of the first projection line near the central axis is defined as B. The ratio of the radius of the centrifugal fan to the distance L1 between the endpoints A and B of the first projection line is greater than or equal to 4 and less than or equal to 7.

5. The distance L1 between the endpoints A and B of the first projection line is greater than or equal to 5 mm and less than or equal to 11 mm.

2. The sander according to claim 1, characterized in that: The sander also includes: An electric motor is used to provide a power source for the airflow element; A battery pack is used to provide a power source for the motor; When the sander is in an unloaded state, the working time of the sander when the battery pack consumes 10WH of energy is defined as the functional time T of the sander. The product of the motor's no-load speed N and the sander's power supply time T is greater than or equal to 63,000 rpm.min and less than or equal to 120,000 rpm.min.

3. The sander according to claim 1, characterized in that... ； The sander also includes: An electric motor is used to provide a power source for the airflow element; A battery pack, used to provide a power source for the motor; When the sander is in an unloaded state, the working time of the sander when the battery pack consumes 10WH of energy is defined as the functional time T of the sander. The product of the motor's no-load speed N and the sander's power supply time T is greater than or equal to 77,000 rpm.min and less than or equal to 110,000 rpm.min.

4. The sander according to claim 1, characterized in that: The farthest point of the airflow element from the central axis forms a circle as the airflow element rotates around the central axis in the preset direction. The distance from the guide wall to the circle is defined as the second distance D2, which gradually increases along the preset direction of rotation.

5. The sander according to any one of claims 1 to 4, characterized in that: The inner wall includes at least one structural segment that satisfies the Archimedes spiral equation along a plane perpendicular to the central axis.

6. The sander according to claim 1, characterized in that: The centrifugal fan includes: The chassis is capable of rotating around the central axis; Multiple fan blades are either fixedly connected to the chassis or integrally formed therefrom; The fan blades extend along a curve, and the direction of the curve is opposite to the preset rotation direction of the centrifugal fan.

7. The sander according to claim 1, characterized in that: The product of the weight of the centrifugal fan and the square of the outer diameter of the centrifugal fan is greater than or equal to 3000 g·mm² and less than or equal to 10000 g·mm².

8. The sander according to claim 1, characterized in that: The centrifugal fan includes: The chassis is capable of rotating around the central axis; Multiple fan blades are either fixedly connected to the chassis or integrally formed therefrom; The wind blade section is defined with a first wind blade surface and a second wind blade surface. Along the preset rotation direction, the first wind blade surface is disposed in front of the second wind blade surface. The two opposite ends of the first and second wind blades respectively converge to form a front edge and a rear edge, and the front edge is farther away from the central axis relative to the rear edge; The outer edge of the chassis is in at least partial contact with the front edge.

9. The sander according to claim 8, characterized in that: The sander also includes: An electric motor is used to provide a power source for the airflow element, and the electric motor is used to drive the centrifugal fan to rotate around the central axis; The base plate can be driven by the motor; The tangent line of the first projection line that is furthest from the central axis is defined as the first tangent line; In the plane formed by the X-axis and Y-axis, the tangent line at the intersection of the outer edge of the chassis and the first projection line is defined as the second tangent line; The angle between the first tangent and the second tangent is greater than or equal to 20 degrees and less than or equal to 45 degrees.

10. The sander according to claim 9, characterized in that: The fan blades are located on the side closest to the base plate.

11. The sander according to claim 1, characterized in that: The centrifugal fan weighs less than or equal to 100g.

12. An airflow chip removal device suitable for a sander, comprising: The airflow element is capable of rotating around its central axis in a preset direction to generate a chip removal airflow. An electric motor is used to provide a power source for the airflow element; A battery pack, used to provide a power source for the motor; Its features are: The airflow chip removal device for sanders also includes: A chip removal housing is configured to house the airflow element and guide the chip removal airflow generated by the airflow element; The inner wall of the chip removal housing is formed with a guide wall, and the distance from the guide wall to the central axis is defined as a first distance D1, which gradually increases along the preset direction of rotation. When the motor is in an unloaded state, the working time of the chip removal device under the condition that the battery pack consumes 10WH of energy is defined as the power supply time T of the chip removal device. The product of the motor's no-load speed N and the chip removal device's power supply time T is greater than or equal to 77,000 rpm.min and less than or equal to 110,000 rpm.min; The airflow element is a centrifugal fan, which includes a chassis and multiple fan blades. The fan blades are substantially perpendicular to the chassis and are defined with a first fan blade surface and a second fan blade surface. The sander further includes: an eccentric element driven by the motor, the eccentric element having an axis offset from the central axis; A coordinate system is established with a point on the central axis as the origin, the direction of the line connecting the central axis to the axis is the X-axis, and the direction perpendicular to the line connecting the central axis to the axis is the Y-axis. The projection of the first wind blade surface onto the plane formed by the X-axis and the Y-axis is defined as the first projection line, and the projection of the second wind blade surface onto the plane formed by the X-axis and the Y-axis is defined as the second projection line. Both the first projection line and the second projection line are arcs in the plane formed by the X-axis and the Y-axis. In the plane formed by the X-axis and Y-axis, the endpoint of the first projection line near the outer edge of the chassis is defined as A, and the endpoint of the first projection line near the central axis is defined as B. The ratio of the radius of the centrifugal fan to the distance L1 between the endpoints A and B of the first projection line is greater than or equal to 4 and less than or equal to 7.

5. The distance L1 between the endpoints A and B of the first projection line is greater than or equal to 5 mm and less than or equal to 11 mm.

13. The airflow chip removal device for a sander according to claim 12, characterized in that: The inner wall includes at least one structural segment that satisfies the Archimedes spiral equation along a plane perpendicular to the central axis.

14. The airflow chip removal device for a sander according to claim 13, characterized in that: The airflow element is a backward-curved centrifugal fan.

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