Impact tool

Abstract

The application discloses an impact tool, comprising a housing, a motor accommodated in the housing, the motor comprising a rotor rotating around a rotating axis, a battery for supplying power to the motor, the battery being connected to or accommodated in the housing, an output shaft driven by the motor, and a transmission mechanism for transmitting the rotation of the motor to the output shaft after deceleration, and an impact mechanism for applying an impact force to the output shaft, the impact mechanism being connected to the transmission mechanism and the output shaft, the impact mechanism comprising a hammer driven by the transmission mechanism and a hammer anvil cooperating with the hammer and being hit by the hammer, the hammer anvil driving the output shaft to rotate, and the impact mechanism further comprising an elastic member arranged between the hammer and the transmission mechanism, the elastic member being capable of shortening or lengthening between the hammer and the transmission mechanism so as to drive the hammer to produce displacement along the deformation direction of the hammer. The impact tool has high working efficiency, stable operation and high reliability.

Description

Technical Field

[0001] This invention relates to an impact tool. Background Technology

[0002] Currently, impact tools on the market, such as impact screwdrivers, impact wrenches, and impact drills, have relatively low no-load output speeds and maximum impact frequencies. The maximum no-load output speed is only about 3,000 rpm, and the maximum impact frequency can only reach about 4,000 impacts per minute, resulting in low working efficiency. Even for the few impact tools that increase no-load output speed and / or maximum impact frequency by increasing motor speed, there are still problems such as a mismatch between the impact frequency and the speed of the impact mechanism under load, leading to machine vibration, fatigue damage or failure of internal parts of the gearbox. Although the machine's working efficiency may be improved in the short term, it brings problems such as unstable operation and low machine reliability. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide an impact tool that is highly efficient, stable in operation, and highly reliable.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] An impact tool includes: a housing; a motor housed within the housing, the motor including a rotor rotating about a rotation axis; a battery for powering the motor, the battery being connected to or housed within the housing; and an output shaft driven by the motor. The impact tool further includes: a transmission mechanism for reducing the rotational speed of the motor before transmitting it to the output shaft; and an impact mechanism for applying an impact force to the output shaft, the impact mechanism connecting the transmission mechanism and the output shaft. The ratio of the motor's rotational speed to the reduction ratio of the transmission mechanism is greater than or equal to 4000 rpm and less than or equal to 7000 rpm, or the maximum impact frequency of the impact tool is greater than or equal to 4350 ipm and less than or equal to 7000 ipm. The impact mechanism includes a hammer driven by the transmission mechanism and an anvil that cooperates with and is struck by the hammer, the anvil driving the output shaft to rotate. The impact mechanism also includes an elastic element disposed between the hammer and the transmission mechanism, the elastic element being capable of shortening or lengthening between the hammer and the transmission mechanism to cause the hammer to displace along its deformation direction, the elastic coefficient K of the elastic element being greater than or equal to 35 N / mm and less than or equal to 70 N / mm.

[0006] Furthermore, the elastic modulus K of the elastic element is greater than or equal to 45 N / mm and less than or equal to 60 N / mm.

[0007] Furthermore, the ratio of the motor speed to the reduction ratio of the transmission mechanism is greater than or equal to 4200 rpm and less than or equal to 6500 rpm and / or the maximum impact frequency of the impact tool is greater than or equal to 4500 ipm and less than or equal to 6500 ipm.

[0008] Furthermore, the ratio of the motor speed to the reduction ratio of the transmission mechanism is greater than or equal to 4000 rpm and less than or equal to 7000 rpm, and the maximum impact frequency of the impact tool is greater than or equal to 4350 ipm and less than or equal to 7000 ipm.

[0009] Furthermore, the transmission mechanism includes a transmission shaft and a ball bearing. The ball bearing is disposed between the transmission shaft and the hammer, and the transmission shaft drives the hammer to rotate through the ball bearing. A ball track for the ball bearing to move is provided radially between the transmission shaft and the hammer. The ball track is approximately V-shaped, and the angle of the ball track trajectory is greater than or equal to 100 degrees and less than or equal to 130 degrees.

[0010] Furthermore, the impact tool also includes a torque adjustment mechanism for allowing the user to manually adjust the output torque of the impact tool. The torque adjustment mechanism is connected to the motor and has multiple adjustment levels. Alternatively, the impact tool also includes a torque adjustment mechanism for adaptively adjusting the output torque of the impact tool. The torque adjustment mechanism includes a motor controller and a sensor assembly that form an electrical or signal connection. The sensor assembly includes a current sensor and / or a torque sensor. The motor controller is electrically connected to the motor.

[0011] Furthermore, the ratio of the hammer's moment of inertia to the output torque of the impact tool is greater than or equal to 1 × 10⁻⁶. -4 kg·mm / N and less than or equal to 2×10 -4 kg·mm / N.

[0012] Furthermore, the ratio of the hammer's moment of inertia to the output torque of the impact tool is equal to 1.2 × 10⁻⁶. -4 kg·mm / N.

[0013] Furthermore, the motor speed is greater than or equal to 12,000 rpm and less than or equal to 28,000 rpm; the reduction ratio of the transmission mechanism is greater than or equal to 3 and less than or equal to 7.

[0014] Furthermore, the motor is an internal rotor motor; the motor includes a stator, the stator includes laminations, the laminations forming multiple magnetic poles extending radially toward the rotation axis; the ratio of the lamination length to the output torque of the impact tool is greater than or equal to 5 × 10⁻⁶. -5 N and less than or equal to 2 × 10 -4 N.

[0015] Furthermore, the ratio of the stack length of the lamination assembly to the output torque of the impact tool is equal to 1 × 10⁻⁶. -4 N.

[0016] Furthermore, the impact tool is an impact screwdriver, impact drill, impact wrench, or electric hammer.

[0017] The advantages of this invention are: it improves the working efficiency of the machine by increasing the no-load output speed or the maximum impact frequency of the impact tool, and improves the stability and reliability of the machine by optimizing the structure of the impact mechanism. Attached Figure Description

[0018] Figure 1 This is a plan view of the impact tool according to the first embodiment of the present invention;

[0019] Figure 2 yes Figure 1 A plan view of part of the structure of the impact tool in the diagram;

[0020] Figure 3 yes Figure 1 A cross-sectional view of a portion of the structure of the impact tool in the image;

[0021] Figure 4 yes Figure 1 A three-dimensional diagram of a portion of the structure of the impact tool in the image;

[0022] Figure 5 yes Figure 1 Exploded view of part of the structure of the impact tool in the image;

[0023] Figure 6 yes Figure 1 A cross-sectional view of a portion of the structure of the impact tool in the image;

[0024] Figure 7 yes Figure 1 A plan view of part of the structure of the impact tool. Detailed Implementation

[0025] Figure 1 A schematic diagram of the impact tool 100 according to the first embodiment of the present invention, wherein, Figure 1 The impact tool 100 is an impact screwdriver. In other embodiments, the impact tool 100 can also be an impact wrench, impact drill, electric hammer, electric pick, or other impact tools, and is not limited here. In fact, any tool that includes the substantive content described below in this invention falls within the scope of protection of this invention. For ease of explanation, this embodiment is provided with the following... Figure 1 The front and back directions are shown.

[0026] like Figures 1 to 3As shown, the impact tool 100 includes a housing 11, a motor 12, and a battery 13. The housing 11 has a receiving space for accommodating the motor 12. The motor 12 includes a stator and a rotor, and the rotor rotates about a rotation axis 101. In this embodiment, the motor 12 is an internal rotor motor, and the rotor includes a motor 12 shaft. The battery 13 supplies power to the motor 12 and is connected to or housed within the housing 11. In this embodiment, the battery 13 is installed at the lower part of the housing 11 and forms a detachable connection with the housing 11 for easy replacement and maintenance. The impact tool 100 also includes an output shaft 15 driven by the motor 12 and a transmission mechanism 14. The drive can be indirect or direct via the transmission mechanism 14. In this embodiment, the rotation of the motor 12 rotor is reduced in speed by the transmission mechanism 14 and then transmitted to the output shaft 15. The motor 12 includes a motor fan 121.

[0027] In this embodiment, the transmission mechanism 14 includes a gearbox housing a planetary gear reduction system. This system is a single-stage reduction system comprising a single row of single-stage planetary gears, specifically a sun gear, a planetary gear carrier 142, planetary gears 143, and a ring gear 144. The ring gear is fixed relative to the gearbox. The planetary carrier 142 includes a cylindrical base and multiple planetary gear shafts (not shown) evenly spaced circumferentially on the end face of the base. Each planetary gear shaft extends from the rear end of the base, and a planetary gear 143 is mounted on each shaft. The motor shaft of the motor 12 extends into the gearbox and meshes with the planetary gears 143 housed therein. Specifically, the motor shaft drives the sun gear to rotate. Of course, the specific structure of the gear transmission in this embodiment is not limited to this; any system that achieves the preset transmission ratio is acceptable.

[0028] The impact tool 100 also includes an impact mechanism 16, which is disposed between and connects the transmission mechanism 14 and the output shaft 15, and is used to apply impact force to the output shaft 15. Specifically, the impact mechanism 16 includes a hammer 161 driven by the transmission mechanism 14 and an anvil 162 that cooperates with and is struck by the hammer 161. The anvil 162 drives the output shaft 15 to rotate. A pair of first end teeth are radially symmetrically protruded on the front end face of the hammer 161, and the front end of the hammer 161 is also provided with the anvil 162. A pair of second end teeth are radially symmetrically protruded on the rear end face of the anvil 162 opposite to the hammer 161. The output shaft 15 extends out of the front end of the gearbox and is connected to the anvil 162. It can be understood that the anvil 162 and the output shaft 15 can be integrally formed or separate independent parts. The front end of the output shaft 15 is provided with a receiving groove to accommodate corresponding working heads, such as screwdrivers, drill bits, extension rods, etc., when different functions are performed. The impact mechanism 16 also includes an elastic element 163 located between the hammer 161 and the transmission mechanism 14. Specifically, the elastic element 163 is a compression spring and is disposed between the hammer 161 and the planetary carrier. The impact mechanism 16 also includes a ball 164 located radially between the hammer 161 and the transmission shaft 141 and a ball track 165 for accommodating the ball 164. In this invention, the ball track 165 is generally V-shaped.

[0029] The impact principle of the impact tool 100 in this embodiment of the invention is described in detail below. The motor shaft of the motor 12 rotates, driving the sun gear to rotate around the planetary gear support shaft. At the same time, the planetary gears crawl along the annular internal teeth of the internal gear ring and revolve around the rotation axis 101 of the motor shaft. The revolution of the planetary gears drives the planet carrier to rotate and transmits the rotation to the drive shaft 141, which is connected to the planet carrier or is integrally formed with the planet carrier. The hammer 161 and the drive shaft 141 are respectively provided with inwardly recessed V-shaped grooves to form a ball track 165. The ball 164 is disposed between the hammer 161 and the drive shaft 141 and embedded in the ball track 165. Thus, the drive shaft 141 drives the hammer 161 to rotate through the ball 164. The hammer 161 drives the anvil 162 to rotate through the cooperation of the anvil 162, which in turn drives the output shaft 15 to rotate. When the impact tool 100 is unloaded, the impact mechanism 16 does not impact; instead, it acts as a transmission mechanism, transmitting the rotation of the motor 12 to the output shaft 15. When the impact tool 100 is loaded, the rotation of the output shaft 15 is obstructed. Depending on the load, the output shaft 15 may rotate at a reduced speed or stop completely. When the output shaft 15 completely stops rotating, the hammer anvil 162 also stops rotating. Due to the limiting effect of the hammer anvil 162 on the hammer 161 in the circumferential direction, the hammer 161 also stops rotating. However, the drive shaft 141 continues to rotate, which causes the ball 164 to be squeezed and move along the trajectory of the ball track 165, thereby driving the hammer 161 to produce an axial displacement and simultaneously squeezing the elastic element 163 until the hammer anvil 162 and the hammer 161 are completely separated. At this time, the drive shaft 141 drives the hammer 161 to rotate at a certain speed, and the elastic element 163 rebounds axially. At this time, the relative speed between the hammer 161 and the hammer anvil 162 is the speed of the hammer 161. When the hammer 161 rotates to contact the hammer anvil 162, it will apply an impact force to the hammer anvil 162. Under the action of this impact force, the output shaft 15 continues to rotate at a certain angle to overcome the load. Then the output shaft 15 stops rotating again, and the above process is repeated. Since the impact frequency is large enough, a relatively continuous impact force will be generated on the output shaft 15, thereby making the working element work continuously. Specifically, for every revolution of the drive shaft 141, the hammer 161 applies two impacts to the output shaft 15, and the impact frequency at this time is the maximum impact frequency.

[0030] When the load is not large enough, the impact process when the output shaft 15 rotates continuously but its rotational speed decreases is roughly the same as when the load is large enough. The specific implementation principle is the same. The difference is that the output shaft 15 still rotates in the same direction as the transmission shaft 141 at a certain speed. This makes the relative rotational speed between the hammer anvil 162 and the hammer 161 smaller when the elastic element 163 rebounds. At this time, the average number of impacts applied by the hammer 161 to the output shaft 15 per revolution of the transmission shaft 141 is less than or equal to two, and the impact frequency is less than or equal to the maximum impact frequency.

[0031] The above-described process describes the impact process when the impact frequency matches the rotational speed of the impact mechanism 16. However, to improve the working efficiency of the impact tool 100, we need to increase the output rotational speed of the impact tool 100 under no-load and / or the maximum impact frequency under load. Specifically, in this invention, the ratio of the rotational speed of the motor 12 to the reduction ratio of the transmission mechanism 14 is greater than or equal to 4000 rpm and less than or equal to 7000 rpm, and / or the maximum impact frequency of the impact tool 100 is greater than or equal to 4350 ipm and less than or equal to 7000 ipm. Further, the ratio of the rotational speed of the motor 12 to the reduction ratio of the transmission mechanism 14 is greater than or equal to 4200 rpm and less than or equal to 6500 rpm, and / or the maximum impact frequency of the impact tool 100 is greater than or equal to 4500 ipm and less than or equal to 6500 ipm. Specifically, the implementation method is as follows: the rotational speed of the motor 12 is greater than or equal to 12000 rpm and less than or equal to 28000 rpm; the reduction ratio of the transmission mechanism 14 is greater than or equal to 3 and less than or equal to 7. Specifically, in this embodiment, the ratio of the speed of the motor 12 to the reduction ratio of the transmission mechanism 14 is equal to 4000 rpm, which is achieved by using a motor 12 with a speed of 2000 rpm and a reduction ratio of 5, thereby increasing the no-load output speed of the impact tool 100.

[0032] When the no-load output speed of the impact tool 100 increases, the speed of the impact mechanism 16 also increases. If the entire transmission mechanism 14 and the impact mechanism 16 still use the structure from the low-speed version, a mismatch between the impact frequency and the speed of the impact mechanism 16 may occur, further leading to problems such as impact point displacement and reduced impact frequency. Specifically, impact point displacement means that the hammer 161 and the anvil 162 may not make complete contact during impact, and the hammer 161 may strike part of the anvil 162. This will cause fatigue damage or failure of the impact mechanism 16, and will also cause machine vibration, resulting in a poor user experience. The reduced impact frequency is due to the decrease in the relative speed of the hammer 161 and the anvil 162.

[0033] To address the above problems, this invention optimizes the structure of the impact mechanism 16, enabling a better match between the impact frequency and the rotational speed of the impact mechanism 16, thereby avoiding the aforementioned issues. Specifically, through analysis and experimentation, we found that the main factors affecting the matching degree between the impact frequency and the rotational speed of the impact mechanism 16 are the elastic coefficient of the elastic element 163, the angle of the ball track 165 trajectory, and the moment of inertia of the hammer 161. The impact frequency and the rotational speed of the impact mechanism 16 can be better matched by adjusting the elastic coefficient of the elastic element 163, the angle of the ball track 165 trajectory, and the moment of inertia of the hammer 161. Specifically, in this embodiment, adjusting the elastic coefficient K of the elastic element 163 reduces the axial rebound time of the elastic element 163, thereby matching the increased rotational speed. Specifically, the elastic coefficient K is greater than or equal to 35 N / mm and less than or equal to 70 N / mm; further, the elastic coefficient K is greater than or equal to 45 N / mm and less than or equal to 60 N / mm. In this embodiment, the elastic coefficient K is 45 N / mm. As an alternative implementation, the angle α of the ball track 165 is adjusted, such as... Figure 7 As shown, the trajectory angle α of the ball track 165 is greater than or equal to 100 degrees and less than or equal to 130 degrees. As another alternative implementation, the moment of inertia of the hammer 161 was fine-tuned. Those skilled in the art should understand that for impact tools 100 with different output torques, the size and mass of the hammer 161 vary considerably, resulting in a wide range of moment of inertia for the hammer 161. Here, through multiple experimental analyses, we determined that the ratio of the moment of inertia of the hammer 161 to the output torque of the impact tool 100 is greater than or equal to 1 × 10⁻⁶. -4 kg·mm / N and less than or equal to 2×10 -4 kg·mm / N. It should be noted that the above three methods for improving the matching degree between the impact frequency and the rotational speed of the impact mechanism 16 can be used simultaneously, or only one or two of them can be used. In this embodiment, the ratio of the moment of inertia of the hammer 161 to the output torque of the impact tool 100 is equal to 1.2 × 10⁻⁶. -4 kg·mm / N.

[0034] It should be noted that adjusting the elastic coefficient K of the elastic element 163 not only reduces the axial rebound time of the elastic element 163 under large loads, thus facilitating the matching of impact frequency and rotation speed, but also improves the stability of the impact tool 100 under smaller loads. Specifically, when a small load is applied to the output shaft 15, the ball 164 is subjected to a certain compressive force and tends to move along the ball track 165. If the elastic coefficient K of the elastic element 163 is large, a small axial displacement can be generated, preventing the hammer 161 from separating from the anvil 162 and causing a small axial displacement of the hammer 161 relative to the anvil 162. This allows the impact tool 100 to output rotation stably without impact under the load, improving the reliability of the impact tool 100.

[0035] The stator of motor 12 includes laminations, which form multiple magnetic poles extending radially toward the rotation axis 101. Due to the high impact frequency of the impact tool 100, to further improve the stability and reliability of the impact tool 100 during operation, the structure of motor 12 has been optimized. In this embodiment, this is manifested by increasing the lamination length of the laminations. However, the lamination lengths of the motor 12 laminations vary significantly for impact tools 100 with different output torques. Through analysis, we have determined a suitable lamination length range for impact tools 100 with specific output torques. Specifically, the ratio of the lamination length of the laminations to the output torque of the impact tool 100 is greater than or equal to 5 × 10⁻⁶. -5 N and less than or equal to 2 × 10 -4 In this embodiment, the ratio of the stack length of the lamination group to the output torque of the impact tool 100 is equal to 1 × 10⁻⁶. -4 N.

[0036] The impact tool 100 also includes a torque adjustment mechanism for allowing the user to manually adjust the output torque of the impact tool 100. The torque adjustment mechanism is connected to the motor 12 and has multiple adjustment levels. The torque adjustment mechanism includes an operating element for user operation and an regulator electrically connected to the motor 12. The operating element is connected to the regulator, and the user operates the operating element to trigger the regulator to operate. As an alternative implementation, the impact tool 100 also includes a torque adjustment mechanism for adaptively adjusting the output torque of the impact tool 100. The torque adjustment mechanism includes a motor 12 controller and a sensor assembly. The motor 12 controller and the sensor assembly are electrically connected or signal connected. The sensor assembly includes a current sensor and / or a torque sensor. The motor 12 controller is electrically connected to the motor 12.

[0037] 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. An impact tool, comprising: case; An electric motor, housed in the housing, the electric motor comprising a rotor that rotates about a rotation axis; A battery for powering the motor, the battery being connected to or housed in the housing; The output shaft is driven by the motor; Its features are: The impact tool also includes: A transmission mechanism is used to reduce the rotation speed of the motor and then transmit it to the output shaft; An impact mechanism is used to apply an impact force to the output shaft. The impact mechanism connects the transmission mechanism and the output shaft. The ratio of the motor speed to the reduction ratio of the transmission mechanism is greater than or equal to 4000 rpm and less than or equal to 7000 rpm, or the maximum impact frequency of the impact tool is greater than or equal to 4350 ipm and less than or equal to 7000 ipm. The impact mechanism includes a hammer driven by the transmission mechanism and an anvil that cooperates with and is struck by the hammer. The hammer drives the anvil to rotate, and the anvil drives the output shaft to rotate. The impact mechanism also includes an elastic element disposed between the hammer and the transmission mechanism. The elastic element can shorten or lengthen between the hammer and the transmission mechanism, thereby causing the hammer to generate displacement along its deformation direction. The elastic coefficient K of the elastic element is greater than or equal to 35 N / mm and less than or equal to 70 N / mm so that the maximum impact frequency matches the rotational speed of the impact mechanism. Specifically, when a large load is applied to the output shaft, the axial rebound time of the elastic element is reduced; when a small load is applied to the output shaft, the elastic element ensures that the hammer does not detach from the hammer anvil.

2. The impact tool according to claim 1, characterized in that: The elastic coefficient K of the elastic element is greater than or equal to 45 N / mm and less than or equal to 60 N / mm.

3. The impact tool according to claim 1, characterized in that: The ratio of the motor's rotational speed to the reduction ratio of the transmission mechanism is greater than or equal to 4200 rpm and less than or equal to 6500 rpm, or the maximum impact frequency of the impact tool is greater than or equal to 4500 ipm and less than or equal to 6500 ipm.

4. The impact tool according to claim 1, characterized in that: The ratio of the motor's rotational speed to the reduction ratio of the transmission mechanism is greater than or equal to 4000 rpm and less than or equal to 7000 rpm, and the maximum impact frequency of the impact tool is greater than or equal to 4350 ipm and less than or equal to 7000 ipm.

5. The impact tool according to claim 1, characterized in that: The transmission mechanism includes a transmission shaft and a ball. The ball is disposed between the transmission shaft and the hammer. The transmission shaft drives the hammer to rotate through the ball. A ball track is provided between the transmission shaft and the hammer in the radial direction for the ball to move. The ball track is approximately V-shaped, and the angle of the trajectory of the ball track is greater than or equal to 100 degrees and less than or equal to 130 degrees.

6. The impact tool according to claim 1, characterized in that: The impact tool further includes a torque adjustment mechanism for allowing the user to manually adjust the output torque of the impact tool. The torque adjustment mechanism is connected to the motor and has multiple adjustment levels. Alternatively, the impact tool further includes a torque adjustment mechanism for adaptively adjusting the output torque of the impact tool. The torque adjustment mechanism includes a motor controller and a sensor assembly that form an electrical or signal connection. The sensor assembly includes a current sensor and / or a torque sensor. The motor controller is electrically connected to the motor.

7. The impact tool according to claim 1, characterized in that: The ratio of the hammer's moment of inertia to the output torque of the impact tool is greater than or equal to 1 × 10⁻⁶. -4 kg·mm / N and less than or equal to 2×10 -4 kg·mm / N.

8. The impact tool according to claim 7, characterized in that: The ratio of the hammer's moment of inertia to the output torque of the impact tool is equal to 1.2 × 10⁻⁶. -4 kg·mm / N.

9. The impact tool according to claim 1, characterized in that: The motor has a speed greater than or equal to 12,000 rpm and less than or equal to 28,000 rpm; the transmission mechanism has a reduction ratio greater than or equal to 3 and less than or equal to 7.

10. The impact tool according to claim 1, characterized in that: The motor is an internal rotor motor; the motor includes a stator, the stator includes laminations, the laminations having multiple magnetic poles extending radially toward the rotation axis; the ratio of the lamination length to the output torque of the impact tool is greater than or equal to 5 × 10⁻⁶. -5 N and less than or equal to 2 × 10 -4 N.

11. The impact tool according to claim 10, characterized in that: The ratio of the stack length of the lamination group to the output torque of the impact tool is equal to 1 × 10. -4 N.

12. The impact tool according to claim 1, characterized in that: The impact tool is an impact screwdriver, impact drill, impact wrench, or electric hammer.

Images