Electric tool

Abstract

The utility model discloses an electric tool. The electric tool comprises a main body and a head part connected with the main body, wherein the main body comprises a host shell; the motor is accommodated in the host shell and comprises a motor shaft; the fan is mounted on the motor shaft and rotates along with the motor shaft; wherein the head part comprises a head part shell; the transmission device and the resonant cavity are arranged in the inner space of the head shell; wherein the resonant cavity comprises a cavity shell and one or more air inlets formed in the cavity shell; wherein the air inlet is in fluid communication with the interior of the cavity shell; wherein one side face of the air inlet faces the internal space, and the other side face faces the interior of the cavity shell.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power tools, in particular to a power tool comprising a noise reduction device. BACKGROUND

[0002] Noise generated by power tools is mainly from components such as gearboxes, fans, and accessory operations. During the operation of a power tool, the flow rate of air flow generated within the power tool due to various rotating components can reach 70 m / s, resulting in a large amount of noise. This long-standing problem has driven the exploration of innovative noise reduction solutions. Current noise reduction strategies mainly include optimizing fan blade design and housing structure, or using active noise reduction technology. However, these methods can have limitations in effectiveness or potential impact on the overall design and functionality of the power tool.

[0003] The concept of Helmholtz resonance provides a promising approach to solving this difficult problem. A Helmholtz resonator is a sound-absorbing device composed of a rigid cavity connected to the external environment through a neck. The air inside the cavity acts as a mass element, while the pressure fluctuations caused by the inflow and outflow of air through the neck produce a spring-like effect. The resulting vibrations dissipate sound energy, allowing the resonator to absorb sound of a specific frequency.

[0004] The unique structural features of power tools, particularly the irregular cavities within the gearbox due to mold and cooling requirements, provide an opportunity to directly integrate a Helmholtz resonator into the tool design. By utilizing these existing cavities and optimizing the flow channels, noise reduction can be achieved without major modifications to the product appearance or affecting its functionality. Integrating a Helmholtz resonator in a power tool represents a potential paradigm shift in noise reduction strategies, providing a more seamless and effective solution to the long-standing challenge faced by the industry. SUMMARY

[0005] The present application solves the long-standing problem of noise generated by power tools, which has been a nuisance to users and the surrounding environment. By directly integrating a Helmholtz resonator into the gearbox of a power tool, the present application introduces a novel noise reduction method that provides a more targeted and effective noise reduction means without affecting the design or functionality of the tool.

[0006] This application discloses an electric tool, comprising: a body and a head connected to the body; wherein the body includes: a main housing; a motor housed within the main housing and including a motor shaft; and a fan mounted on the motor shaft to rotate therewith; wherein the head includes: a head housing; a transmission device and a resonant cavity disposed within the internal space of the head housing; wherein the resonant cavity includes a cavity shell and one or more air inlets disposed on the cavity shell; wherein the air inlets are in fluid communication with the interior of the cavity shell; wherein one side of the air inlet faces the internal space and the other side faces the interior of the cavity shell.

[0007] According to an optional embodiment, the power tool further includes: an air inlet disposed at the rear end of the main housing; and an air outlet disposed on the head housing; wherein the air inlet and the air outlet define the gas flow path that the airflow passes through the power tool after entering the power tool via the air inlet and before exiting the power tool via the air outlet.

[0008] According to an optional implementation, the resonant cavity is disposed in the gas flow path and partially surrounds the transmission device.

[0009] According to an optional implementation, the dimensions of the cavity shell and the air inlet are designed such that the natural frequency of the resonant cavity matches the air vibration frequency inside the head shell.

[0010] According to an optional implementation, the resonant cavity includes one or more partition walls to divide the cavity housing into multiple sub-cavities; each sub-cavity communicates with one or more air inlets.

[0011] According to an optional embodiment, each partition wall extends in a plane parallel to the axial and lateral directions, and / or in a plane parallel to the transverse and lateral directions, and / or in a plane parallel to the transverse and axial directions.

[0012] According to an optional implementation, each partition wall extends radially about the axial direction, and / or laterally, and / or sideways.

[0013] According to an optional implementation, each partition wall has a non-planar curved shape.

[0014] According to an optional implementation, adjacent partition walls are connected to each other to form a grid-like subcavity arrangement.

[0015] According to an optional implementation, the wall thickness of the cavity shell at the air inlet is increased or decreased.

[0016] Compared with the prior art, the electric power tool according to the present application has the following technical effects. The electric power tool according to the present application integrates the resonator into the gear box, which makes full use of the existing cavity in the gear box and minimizes design changes and additional components. The resonator of the electric power tool according to the present application is specially tuned and can absorb most of the noise generated when the electric power tool is working, especially the noise in the range of human auditory sensitivity. The resonator of the electric power tool according to the present application reduces the noise level and provides a more comfortable and less disturbing working environment for the user. BRIEF DESCRIPTION OF DRAWINGS

[0017] The disclosure of the present application will become more fully understood from the detailed description given herein below, and appended claims, taken with the accompanying drawings. As those skilled in the art will appreciate, the drawings are not intended to limit the scope of the present application, but are merely intended for illustration. It will be appreciated that for simplicity and clarity of illustration, elements drawn to the same scale in the drawings are intended to illustrate the same or similar elements.

[0018] Figure 1 is a perspective view of an angle grinder as an example of the electric power tool according to the present application;

[0019] Figure 2 is a partial cutaway side view of the angle grinder of Figure 1 ;

[0020] Figure 3 is a partial cutaway side view of the angle grinder of Figure 1 ;

[0021] Figure 4 is a perspective view of the head of the angle grinder of Figure 1 ;

[0022] Figure 5 is a partial cutaway perspective view of the head of the angle grinder of Figure 1 ;

[0023] Figure 6 is a partial cutaway side view of the transmission of the angle grinder of Figure 1 ;

[0024] The same reference numerals in the various drawings indicate the same or similar elements. DETAILED DESCRIPTION

[0025] Exemplary embodiments of this application will now be described in more detail with reference to the accompanying drawings. While an angle grinder is shown as an exemplary embodiment of this application in the drawings, it should be understood that this application can be implemented in various other forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art. In other words, those skilled in the art should understand that the power tools of this application are not limited to angle grinders.

[0026] Figure 1 This is a perspective view of an angle grinder, which serves as an example of the power tools described in this application. Figure 2 yes Figure 1 A partial sectional side view of an angle grinder. (e.g.) Figure 1 and Figure 2 As shown, the angle grinder generally includes a main body 10 and a head 20 connected to the main body 10. The main body 10 may include a main housing 12 formed by connecting a motor housing 11 and a component housing 13, a motor 14 housed within the motor housing 11 and including a motor shaft 15, a fan mounted on the motor shaft 15 to rotate therewith, and electrical components housed within the component housing 13 and related support structures supporting the electrical components. The head 20 may include a head housing 22 and a drive mechanism 24 housed within the head housing 22 and including an output shaft 25. The main housing 12 and the head housing 22 together constitute the outer shell of the angle grinder. The angle grinder may also be configured with a guard (not shown) attached to the head 20, which partially surrounds the grinding disc when the grinding disc is mounted to the output shaft 25 to prevent the high-speed rotating grinding disc and generated debris from splashing onto the operator and causing injury.

[0027] The motor housing 11 and the element housing 13 forming the main housing 12 can be integrally formed, or can be separate components that are formed separately and then attached together. The main housing 12 has an outer configuration that is suitable for being held by an operator to operate the angle grinder. Optionally, the main housing 12 includes features for increasing the friction between the hand of the operator and the housing when the hand is held by the operator. The features can include a piece of plastic or rubber material attached to the outer surface of at least a portion of the motor housing 11 and / or at least a portion of the element housing 13, and optionally or additionally, the features can include protrusions and / or recesses formed in the outer surface of the motor housing 11 and / or the element housing 13. One or both of the motor housing 11 and the element housing 13 forming the main housing 12 can be attached from two opposing halves. The trigger switch 101 and the speed control switch 102 are disposed on the motor housing 11 in positions that are convenient for the operator to operate (e.g., press or pull) when the operator is holding the main body 10 to operate, for example, as shown in the positions that are convenient for the operator's right hand index finger (for the trigger switch 101) and thumb (for the speed control switch 102) to operate when the right hand is holding the main body 10. In the illustrated embodiment, the trigger switch 101 and the speed control switch 102 are disposed on opposite sides (top and bottom) of the motor housing 11.

[0028] The main housing 12, and in particular the motor housing 11 thereof, defines a motor space that houses the motor 14. The motor 14 includes the motor shaft 15 described above, as well as a motor rotor and a motor stator that are disposed radially outward from the motor shaft 15. The main housing 12, and in particular the element housing 13 thereof, defines an element space that is in communication with the motor space for housing various electrical elements needed for operation of the angle grinder. These electrical elements include a controller for controlling the motor 14, control or electrical elements for controlling operation of the angle grinder, various switches, etc., which can be mounted on one or more circuit boards. The power cord 19 for connecting to an external power source (e.g., an external AC or DC power source) for powering the motor 14 is also shown. The configuration and structure of the motor 14 and the electrical elements inside the main housing 12 are not the focus of the present application and are not described in detail here. The present application is not limited to power tools that use an external power source to power the motor, and it is possible for the power tool to include a battery pack for powering the motor.

[0029] As Figure 2As shown, in the present application, the direction in which the motor shaft 15 extends is defined as the axial direction A, the motor shaft 15 has a central axis or rotational axis extending along the axial direction A and is rotatable about the same. For the convenience of description, the present application also defines the directional terms "front" and "rear" along the axial direction A. In the axial direction A, the head 20 (and the head housing 22) is located in front of the main body 10 (and the main housing 12), and the element housing 13 of the main housing 12 is located behind the motor housing 11. The directional terms also used in the present application include: the radial direction perpendicular to the axial direction A, the circumferential direction around the axial direction A, the transverse direction T in which the output shaft 25 extends (the transverse direction T is perpendicular to the axial direction A), and the lateral direction L (the lateral direction L is perpendicular to the axial direction A and the transverse direction T).

[0030] The head housing 22 of the head 20 is attached to the motor housing 11 of the main housing 12 of the main body 10 from the front. The head housing 22 can include two opposite halves similar to the two halves of the main housing 12 or can include two halves opposite to each other in the up-down direction. The transmission 24 of the head housing 22 mainly includes an intermediate shaft 241 housed in the head housing 22, a pair of bevel gears (a driving bevel gear 242 and a driven bevel gear 243) and a pair of transmission gears (a driving gear 244 and a driven gear 245), and an output shaft 25 extending out of the head housing 22. The driving bevel gear 242 in the pair of bevel gears is attached to or integrally formed on the motor shaft 15 extending from the motor housing 11 into the head housing 22, so as to be driven by the motor shaft 15 to rotate synchronously with the motor shaft 15 about the central axis of the motor shaft 15 when the motor 14 is started. The driven bevel gear 243 in the pair of bevel gears engaged with the driving bevel gear 242 is attached to or integrally formed on the intermediate shaft 241 parallel to the output shaft 25. The driving gear 244 in the pair of transmission gears is attached to or integrally formed on the intermediate shaft 241. The driven gear 245 in the pair of transmission gears engaged with the driving gear 244 is attached to or integrally formed on the output shaft 25. In this way, the driven bevel gear 243 is rotated by the driving bevel gear 242, which in turn drives the driving gear 244. The driven gear 245 is rotated by the driving gear 244, which in turn drives the output shaft 25 to rotate synchronously about the output axis of the output shaft 25 extending in the transverse direction T. At this point, the transmission 24 converts the rotational movement of the motor shaft 15 about the axial direction A into the rotational movement of the output shaft 25 about the transverse direction T for output. These are no longer described.

[0031] The angle grinder includes an air inlet 32 allowing air flow into the interior of the angle grinder and an air outlet 34 allowing air flow from the interior of the angle grinder to exit the angle grinder, and defines an air flow path along which air flow flows within the angle grinder after entering the angle grinder via the air inlet 32 and before exiting the angle grinder via the air outlet 34. The air inlet 32 and the air outlet 34 are provided on the rear end of the main housing 12 and the head housing 22, respectively. The angle grinder further includes an air guide 60 located on the air flow path. The air guide 60 is located within the main housing 12, specifically the motor housing 11, of the main body 10. The air inlet 32 and the air outlet 34 are located on opposite sides of the air guide 60 on the air flow path, respectively. The air guide 60 is capable of preventing air flow from flowing reversely towards the air inlet 32 on the upstream side. When the motor 14 is started, a fan (not shown) driven by the motor shaft 15 rotates at high speed to draw or suck air into the angle grinder via the air inlet 32, and then the air flow successively flows through and cools the circuit board and electrical elements located within the element housing 13 and the motor 14 located within the motor housing 11, and then the air flow flows through the air guide 60 and exits the angle grinder via the air outlet 34, thereby playing a role of sufficient heat dissipation.

[0032] Figure 3 is a partial cross-sectional side view of the angle grinder of Figure 1 Figure 4 is a perspective view of the head of the angle grinder of Figure 1 Figure 5 is a partial cross-sectional perspective view of the head of the angle grinder of Figure 1 Figure 6 is a partial cross-sectional side view of the transmission of the angle grinder of Figure 1 Due to the requirements of the mold and cooling, the head housing 22 will usually form irregular internal spaces. These internal spaces are the basis of the Helmholtz type muffler.

[0033] As Figures 3 to 6 ​​​​As shown, the head 20 also includes a resonant cavity 21 housed within the head housing 22 and disposed in the gas flow path. The resonant cavity 21 may partially surround the transmission device 24 (e.g., it may serve as a support for the intermediate shaft 241 in the transmission device 24) and includes a cavity housing 211 and an air inlet 212 disposed on the cavity housing 211. Thus, the air inlet 212 is in fluid communication with the interior of the cavity housing 211. One side of the air inlet 212 faces the interior space of the head housing 22. The high-speed rotating fan, the forced high-speed airflow, and various frequencies of noise generated by the aforementioned and other reasons all exist in this space. The other side of the air inlet 212 faces the interior of the cavity housing 211. The airflow caused by the high-speed rotation of the fan flows into and out of the cavity housing 211 through the air inlet 212, and the inflowing and outflowing air creates a pressure difference between the interior and exterior of the cavity housing 211, resulting in air vibration. When the sound wave frequency of the airflow inside the head shell 22 matches the air vibration frequency inside the cavity shell 211, a resonance phenomenon occurs, consuming the energy of the incident sound wave and achieving the absorption of sound waves of a specific frequency.

[0034] In order to obtain different natural frequencies of the Helmholtz-type silencer, the parameters of the cavity shell 211 or the air inlet 212 can be appropriately changed, including but not limited to the extension direction, number, size, and arrangement of the cavity and / or the number, size, and arrangement of the air inlets 212, etc.

[0035] In the illustrated embodiment, the resonant cavity 21 further includes one or more partition walls 213 to divide the cavity housing 211 into multiple sub-cavities, each sub-cavity communicating with one or more air inlets 212. Thus, multiple Helmholtz-type silencing devices are formed. The size of each sub-cavity and the arrangement of the corresponding air inlets 212 can be the same or different to provide Helmholtz-type silencing devices with the same or different natural frequencies, thereby eliminating noise at different frequencies.

[0036] The arrangement of the partition walls 213 can be changed to provide sub-cavities of various sizes or volumes. For example... Figure 3 and Figure 6As shown, each partition wall 213 can extend in a plane parallel to the axial direction A and the lateral direction L. It can be appreciated that in other embodiments, each partition wall 213 can extend in a plane parallel to the transverse direction T and the lateral direction L. In other embodiments, each partition wall 213 can extend in a plane parallel to the transverse direction T and the axial direction A. In other embodiments, each partition wall 213 can extend radially about the axial direction A, the transverse direction T, or the lateral direction L. The partition walls 213 can also have any curved shape that is non-planar. For example, each partition wall 213 can extend helically or in other curvilinear shapes about the axial direction A, the transverse direction T, or the lateral direction L. In other embodiments, partition walls 213 adjacent to each other can be connected to each other to form a grid-like sub-cavity arrangement of various shapes or sizes, as long as each sub-cavity is in communication with one or more of the air inlets 212.

[0037] Different numbers and opening areas of the air inlets 212 can be provided to achieve different resonance frequencies in combination with different sub-cavities. The configuration of the air inlets 212 associated with a sub-cavity can include one or more of the following: the number of air inlets 212 associated with the sub-cavity, the size of each air inlet 212, the arrangement of each air inlet 212 (relative position relationship or distance between the air inlets 212, etc.), the hole depth of each air inlet 212, and the like. The hole depth of an air inlet 212 depends on the wall thickness of the portion of the cavity housing 211 in which the air inlet 212 is located. To achieve different hole depths of the air inlets 212, the wall thickness of the portion of the cavity housing 211 can be locally increased or thinned.

[0038] The basic principles of the present application are described above with respect to the illustrated example of an angle grinder. The present application achieves the technical effect of creating a sound-damping device to eliminate noise without affecting the heat dissipation function, simply by adding the resonance cavity 21 inside the head housing 22 without substantially modifying the structure of the angle grinder.

[0039] As can be appreciated by those skilled in the art after reading the above description, the principles of the present application are not only applicable to angle grinders whose tools are abrasive discs, but are applicable to any power tool that includes a motor, a fan, and a transmission, such as a cutter whose tool is a cutting disc. The principles of the present application are not only applicable to power tools in which the motor shaft and the output shaft are arranged perpendicularly, but are also applicable to power tools in which the motor shaft and the output shaft are arranged substantially parallel or obliquely. The principles of the present application are applicable to power tools that include a multi-stage transmission including a pair of bevel gear engagements and / or a pair of cylindrical gear engagements, and are also applicable to power tools in which the transmission is a single-stage transmission including only one pair of bevel gears.

[0040] Those skilled in the art should understand that the specific description of the basic principles, main features and advantages of the present application above does not limit the present application in any form, and any technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present application.

Claims

1. A power tool characterized by comprising: The electric power tool comprises: a main body (10) and a head (20) connected to the main body (10); wherein the main body (10) comprises: a main housing (12); a motor (14) accommodated in the main housing (12) and comprising a motor shaft (15); and a fan mounted on the motor shaft (15) to rotate therewith; wherein the head (20) comprises: a head housing (22); a transmission (24) and a resonant cavity (21) arranged in an inner space of the head housing (22); wherein the resonant cavity (21) comprises a cavity housing (211) and one or more air inlets (212) arranged on the cavity housing (211); wherein the air inlets (212) are in fluid communication with an interior of the cavity housing (211); wherein one side of the air inlets (212) faces the inner space and the other side faces the interior of the cavity housing (211).

2. The power tool of claim 1, wherein The electric power tool comprises: an air inlet (32) arranged at a rear end of the main housing (12); and an air outlet (34) arranged on the head housing (22); wherein the air inlet (32) and the air outlet (34) define a gas flow path through which a gas flows in the electric power tool after entering the electric power tool via the air inlet (32) and before being discharged from the electric power tool via the air outlet (34).

3. The electric power tool according to claim 2, wherein the resonant cavity (21) is arranged in the gas flow path and partially surrounds the transmission (24).

4. The electric power tool according to claim 3, wherein the cavity housing (211) and the air inlets (212) are dimensioned such that a natural frequency of the resonant cavity (21) matches an air vibration frequency inside the head housing (22).

5. The electric power tool according to any one of claims 1 to 4, wherein the resonant cavity (21) comprises one or more partition walls (213) to divide the cavity housing (211) into a plurality of sub-cavities; each sub-cavity is in communication with one or more air inlets (212).

6. The electric power tool according to claim 5, wherein each partition wall (213) extends in a plane parallel to the axial direction (A) and the lateral direction (L), and / or in a plane parallel to the transverse direction (T) and the lateral direction (L), and / or in a plane parallel to the transverse direction (T) and the axial direction (A).

7. The electric power tool according to claim 5, wherein each partition wall (213) extends radially around the axial direction (A), and / or the transverse direction (T) or and / or the lateral direction (L).

8. The electric power tool according to claim 5, wherein each partition wall (213) has a non-planar curved shape.

9. The electric power tool according to claim 5, wherein adjacent partition walls (213) are connected to each other to form a grid-like sub-cavity arrangement.

10. The electric power tool according to claim 5, wherein a wall thickness of the cavity housing (211) is increased or thinned at the air inlets (212).

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