Rotary impact tool

Abstract

A rotary impact tool comprising: an outer housing and an inner housing at least partially surrounded by the outer housing; a motor mounted in the inner housing, and an impact mechanism connected to the motor and fixedly mounted to the inner housing to define an integrated inner subassembly including the motor and the impact mechanism; at least one resilient isolation element is disposed between the outer housing and the inner housing and extends circumferentially around the inner housing such that the inner subassembly is resiliently isolated from the outer housing. According to the invention, the motor and the impact mechanism are combined to form a separate and integrated internal sub-assembly, which is held in the tool housing only by means of the resilient element, thereby reducing the vibrations experienced by the user by rotating the impact mechanism and the motor of the impact tool.

Description

TECHNICAL FIELD

[0001] The present invention relates to an impact tool, in particular a rotary impact tool capable of applying a rotary impact force to an output portion. BACKGROUND

[0002] During operation, power tools, in particular power tools having an impact mechanism, such as impact wrenches, will generate vibrations which can affect the components and the user and can even lead to premature failure of the impact tool or harm the health of the user. Daily exposure limits for hand-arm vibration (HAV values) and use duration limits are defined by international standards for electrical devices and by occupational health and safety legislation in specific countries. If these limits are reached, further work is prohibited. The negative effects of vibrations on ergonomics and health are increasingly recognized, and it has therefore become a competitive differentiator in the sale of power tools.

[0003] For example, in an impact wrench, the movement of the motor, the transmission gears and the tangential impact mechanism will generate excitations in the form of vibrations during operation. Most of these excitations occur on the axis of rotation of the tangential impact mechanism, but there is also a considerable proportion of excitations perpendicular to the axis of rotation and rotation. These excitation forces will be transmitted to the bearing seat on which the motor and the impact mechanism are mounted. If the bearings of the motor and the impact mechanism inside the housing are formed by direct contact without damping, these excitations will be transmitted one-to-one or even amplified by resonance effects. These excitations will be transmitted to the user via the handle in the housing, another housing surface in contact with the user, or another handle mounted on the tool, resulting in high HAV values.

[0004] Furthermore, the power density of power tools has been increasing, and therefore more and more cooling air needs to be supplied to the motor and the electronics. In order to cool the electrical or electronic devices efficiently, it is common to choose a location close to the electrical or electronic devices as the cooling air inlet, so that the external "cold" air enters the electrical or electronic devices first in "suction mode". This requires the installation of a closed air duct between the motor fan and the electronics to avoid a detour of the cooling air.

[0005] Patent document US 7152695 B has disclosed an impact tool comprising a tool housing having a first part and a second part, each part comprising an inner surface and an outer surface, and a tool housing air inlet or a tool housing air outlet. A motor can be mounted in the tool housing and comprises a motor housing having an outer surface and an air inlet for directing cooling air into the motor and an exhaust port for exhausting hot exhaust gases from the motor. The motor housing air inlet and exhaust port are open at the outer surface of the motor housing, the motor housing exhaust port can be spaced apart from the motor housing air inlet. A sheath can be resiliently connected to the outer surface of the motor housing, a radial flange is provided between the air inlet and the exhaust port. The radial flange can have a portion extending into and coupled between the first part and the second part to provide a damping effect, and forms a barrier between the air inlet and the exhaust port, thereby substantially preventing exhaust gases of the exhaust port from entering the air inlet.

[0006] However, US 7152695 B only describes the decoupling of the motor housing and the tool housing. The gear box serving as an impact mechanism is still rigidly connected to the tool housing, and the origin of the tool vibration is the workpiece reaction force acting on the output shaft of the tool during use; when the impact mechanism is still rigidly connected to the tool housing, the vibration is also directly transmitted to the tool housing. Here, the elastic sheath, which can only achieve the attenuation of the knocking vibration transmitted to the motor, cannot bear or transmit the reaction force of the tool use, and cannot truly reduce the impact vibration transmitted to the user's arm. SUMMARY

[0007] The object of the present invention is to provide a rotary impact tool in which the motor and the impact mechanism are combined to form a unit similar to a sub-chassis, which is held in the tool housing only by means of elastic elements, thereby reducing the vibration experienced by the user due to the impact mechanism and the motor of the rotary impact tool.

[0008] According to an embodiment of the present invention, a rotary impact tool comprises an outer housing and an inner housing at least partially surrounded by the outer housing; a motor mounted in the inner housing and an impact mechanism connected to the motor and fixedly mounted to the inner housing to define an integrated inner sub-assembly comprising the motor and the impact mechanism; at least one elastic isolation element disposed between the outer housing and the inner housing and extending circumferentially around the inner housing, such that the inner sub-assembly is elastically isolated from the outer housing. In the present invention, the inner sub-assembly is formed by the motor and the impact mechanism being fixedly mounted to the inner housing, and the sub-assembly is supported in the outer housing only by means of the elastic isolation element; in this way, the amount of vibration transmitted from the impact tool to the user's hand and arm during use is effectively reduced.

[0009] The inner housing is substantially cylindrical with a first end open forwardly and a second end closed rearwardly, the motor is mounted in the inner housing on one side close to the second end, the impact mechanism is fixedly mounted to the first end of the inner housing, the outer housing has substantially the same shape as the inner housing in the axial direction, and the inner surface of the outer housing has a larger diameter than the outer surface of the inner housing, wherein the support is only provided by the isolation element between the outer housing and the inner housing. By means of the additionally provided inner housing, an independent and integrated inner subassembly is formed by the motor and the impact mechanism, and the support is only provided by the elastic isolation element between the outer housing and the inner subassembly without rigid connection, so that the reaction force acting on the output part will be attenuated by the elastic isolation element, thereby achieving complete decoupling between the inner subassembly and the outer housing.

[0010] The isolation element includes a first isolation element and a second isolation element, which respectively surround the circumferential outer surfaces close to the first end and the second end of the inner housing. The first isolation element is arranged at the first end close to the impact mechanism, thereby ensuring better vibration damping effect. Arranging the second isolation element close to the rear end of the impact tool helps to achieve structural balance and stability.

[0011] The outer surface of the inner housing and the inner surface of the outer housing are respectively provided with corresponding first positioning structures and corresponding second positioning structures, the first isolation element is received in the first positioning structure, and the second isolation element is received in the second positioning structure. Since the inner subassembly is only supported in the outer housing by the isolation element, the axial positioning of the isolation element is particularly important, and the positioning mechanism here ensures that the isolation element will not disengage from the outer surface of the inner housing or the inner surface of the outer housing. The axial movement between the outer housing and the inner housing is only the elastic deformation of the isolation element.

[0012] The handle extends below the outer housing, a power source is connected to the lower end of the handle, and the electronic components connecting the power source and the motor are housed in the handle. The handle, which is gripped by the user, is integrated with the outer housing and is elastically isolated from the inner subassembly, so the vibration of the inner subassembly will be attenuated by the elastic isolation element, and the amount of vibration transmitted to the handle will be significantly reduced.

[0013] An air inlet for drawing in outside air is provided on the handle or on the outer housing between the first and second positioning structures. The outer housing has an exhaust port located further rearward than the second positioning structure. An air inlet is located in the portion of the inner housing between these two insulating elements, and an air outlet is located further rearward than the second positioning structure. Therefore, the insulating elements also function as air baffles. The air inlet draws in cool outside air, which, driven by the motor's fan, passes through the air inlet of the inner housing into the motor, flows past the electronic components and / or the motor, and then exits from the air outlet behind the second insulating element, and finally from the exhaust port of the outer housing. The intake and exhaust channels are separated by the insulating elements; in this way, the redirection of the external cooling air is prevented, and the cooling effect is improved.

[0014] The motor includes a fan located at the rear of the motor and a drive shaft located at the front of the motor. An air inlet is located on the inner housing corresponding to the drive shaft and facing the handle. Because the fan is positioned at the rear of the motor and the air inlet at the front, cooling air can flow through the motor. Since the air inlet of the inner housing faces the handle, outside air flows through and cools the electronic components in the handle before directly entering the inner housing to cool the motor, thus creating an optimized aerodynamic path.

[0015] The air outlet on the inner housing is positioned roughly opposite the exhaust port on the outer housing. Therefore, the heated exhaust is directly discharged, preventing it from re-entering the tool and affecting cooling.

[0016] According to embodiments of the invention, the isolation element comprises a uniform, continuous annular shape. Alternatively, the element may be composed of two or more parts to facilitate assembly or manufacture. Since the inner housing is substantially cylindrical, the annular isolation element surrounds the inner housing, thereby providing elastic deformation with six degrees of freedom.

[0017] According to another embodiment of the invention, the isolation element includes an annular shape having a form-fitting portion in the circumferential direction. The form-fitting portion in the circumferential direction of the isolation element can prevent circumferential movement of the outer housing relative to the inner housing.

[0018] The isolation element further includes axially extending protrusions that are discretely distributed in the circumferential direction of the annular shape to increase the strength of the isolation element in the axial direction.

[0019] According to another embodiment of the invention, the rearward second end of the outer housing is not closed, and the outer housing only surrounds the inner housing in the axial direction. This helps to reduce the overall length of the tool; furthermore, the open second end can be used as a general vent, eliminating the need for an additional vent.

[0020] According to another embodiment of the invention, the rearward second end of the outer housing is closed, having a rear end face substantially perpendicular to the axial direction, and a third elastic isolation element is provided between the rear end face of the outer housing and the second end face formed at the closed second end of the inner housing. Therefore, additional vibration decoupling is provided between the outer housing and the inner subassemblies; furthermore, cushioning can be provided in the event of an impact tool falling, thereby preventing damage to the impact tool.

[0021] The insulating element is formed of polyurethane foam. The insulating element must possess sufficient strength, good abrasion resistance and UV resistance, and also have the same service life as the inner and outer shells formed of plastic; research has found that polyurethane foam is a material possessing all these properties. Attached Figure Description

[0022] The above embodiments can be better understood through the following detailed description with reference to the accompanying drawings. It should be emphasized that the components are not necessarily drawn to scale. In fact, dimensions can be increased or decreased arbitrarily for clarity. In the drawings, the same reference numerals denote the same elements.

[0023] Figure 1 This is a complete schematic diagram of the rotating impact tool in an embodiment of the present invention.

[0024] Figure 2 yes Figure 1 A partial schematic diagram of the rotary impact tool is shown, with a portion of the outer housing removed.

[0025] Figure 3 This is an axial cross-sectional view of the rotary impact tool in an embodiment of the present invention.

[0026] Figure 4 This is a partial schematic diagram of a rotating impact tool according to another embodiment of the present invention.

[0027] Figure 5 This is a partial schematic diagram of a rotating impact tool according to another embodiment of the present invention.

[0028] Figure 6 This is a partial schematic diagram of a rotating impact tool according to another embodiment of the present invention. Detailed Implementation

[0029] The following is for reference. Figures 1 to 6The rotary impact tool of the present invention is described below. The following description is merely exemplary and does not limit the disclosure of this application or the application or use of the invention. In the description of the invention, it should be understood that orientations or positional relationships indicated by terms such as “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “axial,” “radial,” and “circumferential,” based on the orientations or positional relationships shown in the accompanying drawings, are used only to facilitate and simplify the description of the invention, and are not intended to indicate or imply that the mentioned device or element must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be construed as limiting the invention.

[0030] Figures 1 to 3 An exemplary rotary impact tool, such as an impact wrench 1, is shown. The impact wrench 1 includes an outer housing 2 and an inner housing 3, at least partially surrounded by the outer housing 2, wherein a motor 4 and an impact mechanism 5 are housed within the inner housing 3. The impact mechanism 5 includes an output shaft 6, wherein the impact mechanism 5 can apply impact to the output shaft 6, located on the working axis 7, in a rotational direction about the working axis 7, driven by the motor 4. A handle 29 extends from below the outer housing 2, allowing the user to grip and guide the impact wrench 1 during operation. An on / off button is provided on the handle 29, by means of which the motor 4 can be turned on or off. A battery or AC power source can be connected to the lower portion of the handle 29, and electronic components 13 connecting the power source and the motor are housed within the handle 29. Preferably, the lower portion of the handle 29 has an extension portion to serve as an interface for battery connection; the electronic components 13 are deployed near the battery connection interface to simplify wiring layout and improve heat dissipation. Alternatively, the electronic components can be arranged behind the motor. In this scenario, the inhaled cold air will first be directed through the motor and then through the electronic components.

[0031] The outer housing 2 can be injection molded from a suitable composite material. In some embodiments, the outer housing 2 may include two substantially symmetrical half-shells; these half-shells have an upper portion 20 extending substantially in the axial direction of the working axis 7, and a half-shell that gradually transitions from the upper portion into a handle 29 formed by extending downward. The two half-shells are assembled together by fasteners (such as screws) to form a substantially axially extending hollow tube shape. The upper portion of the tube shape of the outer housing 2 includes a front end facing the output shaft 6 and a rear end 22 opposite to and away from the output shaft 6. The front end 21 is open and has a substantially annular cross-sectional profile. Preferably, the inner surface 23 of the outer housing is substantially circular; a suitable shape is selected for the outer surface 24 according to the industrial design requirements of the tool. ReferenceFigures 3 to 5 According to an embodiment of the invention, the rear end 22 is open. According to another embodiment of the invention, the rear end 22 is closed and has a rear end face 25 that is substantially perpendicular to the working axis 7; this is described in further detail below.

[0032] Similar to the outer housing 2, the inner housing 32 can also be injection molded from a suitable composite material. For example, the inner housing 3 can be formed from a cup-shaped portion into which the motor will be mounted from the front. The inner housing 3 can also include two substantially symmetrical half-shells assembled together to form a cylindrical structure. It should be understood that the inner housing 3 can also be formed integrally. The inner housing 3 has a first end 31 that opens forward and a second end 32 that closes backward; a second end face 35, substantially perpendicular to the working axis 7, is formed at the closed second end 32. The portion of the inner housing 3 extending axially between the first end 31 and the second end 32 has an outer surface 34 and an inner surface 33, the inner surface having a substantially annular cross-sectional profile.

[0033] The motor 4 is mounted in the inner housing on the side near the second end 22, and the fan 8 is located behind the motor 4. The inner surface 33 of the inner housing 3 is provided with radially inwardly extending ribs, thereby providing a mating form between the motor 4 and the inner housing 3 so as to fix the motor 3 in the inner housing in the axial and rotational directions.

[0034] Motor 4 includes a drive shaft 9 that extends to a region in front of the motor and connects to impact mechanism 5. According to an embodiment of the invention, impact mechanism 5 includes a gear transmission component, a main shaft, a hammer, and an output shaft 6, as well as a gearbox 10 housing these components. The aforementioned gear transmission component and hammer have the following well-known structure: the gear transmission mechanism meshes with the drive shaft 9, converting the high-speed rotation of the drive shaft 9 of motor 4 into rotation of the output shaft 6 by reducing speed, and transmitting torque to the hammer, which repeatedly engages and disengages with the output shaft 6, thereby generating an impact in the rotational direction.

[0035] refer to Figure 3 and Figure 4The gearbox 10 is a tubular body. Its rear portion inserts into the inner housing 3 and engages with the bearing housing of the gear transmission component mounted within the inner housing 3. The front portion of the gearbox 10, exposed at the first end 31 of the inner housing 3, has a forward-tapering shape and can be covered by a protective cover made of synthetic resin. The output shaft 6 is supported at the front end of the gearbox 10 and protrudes forward. Mounting holes are provided on the outer periphery of the gearbox 10 at the exposed position at the first end 31 of the inner housing 3, allowing the gearbox 10 to be securely mounted to the first end 31 of the inner housing 3 by fasteners 11. Therefore, the motor 4 and the impact mechanism 5 are both securely mounted within the inner housing, eliminating the need for direct axial fixation between the motor 4 and the impact mechanism 5. Overall, the motor 4, the impact mechanism 5, the output shaft 6, and the inner housing 3 define an internal sub-assembly independent of the outer housing 2.

[0036] refer to Figures 3 to 6 The outer housing 2 has a substantially the same shape as the inner housing 3 in the axial direction, and the inner surface 23 of the outer housing 2 has a larger diameter than the outer surface 34 of the inner housing 3. At least one elastic isolation element 12 is disposed between the inner surface 23 of the outer housing 2 and the outer surface 34 of the inner housing 3, and extends around the circumferential direction of the inner housing 3, so that the inner subassembly is elastically isolated from the outer housing. As described above, in this invention, the inner subassembly is formed by fixing the motor 4 and the impact mechanism 5 to the inner housing 3. The main vibration sources in the impact tool are the vibration caused by the reaction force acting on the output shaft 6 of the impact tool during use of the workpiece being processed, the vibration generated by the hammer of the impact mechanism 5 during the striking process, and the vibration generated by the motor 4 during the rotation process; all these vibration sources are integrated in the inner subassembly. The inner subassembly is supported in the outer housing 2 only by the elastic isolation element 12, without any rigid connection, thus the elastic isolation element 12 achieves vibration decoupling between the outer housing 2 and the inner subassembly. The isolation element 12 attenuates vibration transmission from the internal subassembly to the outer housing 2, and almost no vibration generated by the internal subassembly is transmitted to the handle 29 below the outer housing 2. Therefore, when gripping the handle 29 below the outer housing 2, the user's hand will not be affected, thus meeting the requirements for daily exposure limit (HAV value) and duration of use limit for arm vibration.

[0037] According to a preferred embodiment of the present invention, the isolation element 12 includes a first isolation element 121 and a second isolation element 122, which surround the circumferential outer surfaces of a first end 31 and a second end 32 of the inner housing 3, respectively. Positioning the first isolation element 121 near the first end 31 of the impact mechanism 5 provides better vibration damping. Positioning the second isolation element 122 near the rear end of the impact tool helps achieve structural balance and stability. It should be understood that the isolation element 12 of the present invention is not limited to two; for example, the isolation element 12 may be a single isolation element extending substantially axially from the first end of the inner housing toward the second end, but assembly may be relatively complex. Three, four, or more isolation elements 12 may also co-support each other between the inner and outer housings, but in this case, structural complexity and assembly difficulty are also likely to arise.

[0038] Since the internal sub-component is supported in the outer housing 2 only by means of the elastic isolation element 12, the isolation element 12 is subjected to axial shear force and deforms when the impact mechanism 5 is subjected to the reaction force of the workpiece and vibrates axially; in this way, the vibration damping effect is achieved. That is, all relative movement between the outer housing 2 and the inner housing 3 is caused by the elastic deformation of the isolation element 12, and should not be the physical movement of the isolation element relative to the outer housing or the inner housing. To ensure the axial positioning of the isolation element 12, the outer surface 34 of the inner housing 3 is provided with a positioning structure 36 for supporting and positioning the isolation element; correspondingly, the inner surface 23 of the outer housing 2 is provided with a corresponding positioning structure 26 for supporting and positioning the isolation element. In the illustrative embodiment of the present invention, the positioning structure 36 of the inner housing 3 is formed as an annular groove extending radially outward along the outer surface of the inner housing, and the isolation element can be received in the annular groove. The positioning structure 26 of the outer housing 2 is formed as an annular groove extending radially inward along the inner surface of the outer housing, its position aligned with the annular groove on the inner housing, and the isolation element 12 can be clamped in the two annular grooves.

[0039] Preferably, there are also two positioning mechanisms. The first isolation element 121 is received in the first positioning structures 361, 261, and the second isolation element 122 is received in the second positioning structures 362, 262. Here, the positioning mechanism ensures that the isolation element will not disengage from the outer surface of the inner housing or the inner surface of the outer housing; the axial movement between the outer housing and the inner housing is merely the elastic deformation of the isolation element.

[0040] The isolation element 12 comprises a substantially annular structure; since the inner housing is substantially tubular, the annular isolation element surrounds the inner housing, thereby providing elastic deformation with six degrees of freedom. The thickness of the annular shape is substantially equal to or slightly greater than the difference between the radius of the inner surface of the outer housing and the radius of the outer surface of the inner housing, ensuring that the inner subassembly can be supported within the outer housing solely by the isolation element 12. The axial length of the annular shape can be appropriately determined based on the power of the impact tool and the material of the isolation element. Preferably:

[0041] According to another embodiment of the present invention, reference Figure 4 The second isolating element 122 is a uniform, continuous annular shape. Since the second isolating element 122 is positioned near the second end of the inner housing where the motor is mounted, the annular shape is the most space-saving form because it conforms to the intended circular shape of the motor. It is understood that the isolating element can be composed of two or more parts for ease of assembly or manufacture. The first isolating element 121 includes an annular shape having a form-fitting portion 124 in the circumferential direction. Because the gearbox 10 is fixedly mounted to the end face of the first end 31 of the inner housing 3 by fasteners such as screws, the cross-section of the inner housing 3 at the first end 31 perpendicular to the working axis 7 is not a regular circle, but rather a square-within-a-circle shape, which has a slightly outward-protruding fastener mounting portion at the fastener mounting location. The first isolation element 121 similarly has a form-fitting portion in the circumferential direction, which is adapted to the fastener mounting portion so that the first isolation element 121 fits perfectly between the inner housing 2 and the outer housing 3; this not only prevents the outer housing from moving circumferentially relative to the inner housing, but also creates an air gap between the outer housing 2 and the inner housing 3.

[0042] refer to Figure 5 According to another embodiment of the invention, the isolation element 12 further includes axially extending protrusions 125, which are discretely distributed in the circumferential direction of the annular shape to increase the strength of the isolation element in the axial direction; this results in better vibration damping and a longer service life.

[0043] refer to Figure 6 According to another embodiment of the invention, the second end 22 of the outer housing 2 is closed and has a rear end face 25 substantially perpendicular to the working axis, and a third elastic isolation element 123 is provided between the rear end face 25 of the outer housing and the second end face 35 formed at the closed second end of the inner housing. Therefore, additional vibration decoupling is provided between the outer housing and the inner subassembly; furthermore, cushioning can be provided when the impact tool is dropped, thereby preventing damage to the impact tool.

[0044] Refer again Figures 1 to 3An air inlet 27 for drawing in external "cold" air is located on the handle 29 near the electronic components 13. The outer housing 2 has an exhaust port 28 located further rearward than the second positioning structure 262. The inner housing 3 has an air inlet 37 in the portion between the first positioning structure 361 and the second positioning structure 362, and an air outlet 38 located further rearward than the second positioning structure 362. Therefore, the air inlet 27 on the handle 29 draws in external cold air, which, after cooling the electronic components 13 housed in the handle 29, enters the inner housing through the air inlet 37 of the inner housing 3 under the action of the fan 8 of the motor 4, flows through the motor 4, and then exits from the air outlet 38 behind the second positioning structure 362, and then exits from the exhaust port 28 of the outer housing. Since the first isolation element 121 and the second isolation element 122 are clamped and positioned to perfectly fit between the first positioning structures 261, 361 and the second positioning structures 262, 362, the isolation elements also function as air baffles. External air drawn in from below the handle is confined within the gap 14 between the first isolation element 121 and the second isolation element 122 between the outer and inner housings; this prevents the external cooling air from being redirected, resulting in better cooling. Furthermore, because the fan 8 of the motor 4 is located at the rear of the motor 4, the rotation of the fan 8 creates a negative pressure in front of the motor; under this negative pressure, the external airflow drawn into the handle can only enter the cavity of the inner housing through the air inlet 37 located between the first positioning structure 361 and the second positioning structure 362, and after cooling the motor, it is discharged through the air outlet 38 to the area behind the second isolation element 122. At this time, the heated exhaust gas is blocked by the second isolation element 122 and therefore does not flow back into the gap 14 between the first isolation element 121 and the second isolation element 122 between the outer and inner housings.

[0045] Alternatively, the air inlet 27 can be located on the outer housing, between the first positioning structure 261 and the second positioning structure 262. Since the electronic components are located directly behind the motor, in this case, the drawn-in cold air will first be directed through the motor and then through the electronic components.

[0046] According to a preferred embodiment of the present invention, such as Figure 2 As shown, the air inlet 37 is located on the inner housing at a position corresponding to the drive shaft 9 and facing the handle 29. The fan 8 is located behind the motor 4, and the air inlet 37 is located in front of the motor 4; therefore, external cooling air drawn in through the air inlet 27 below the handle flows over and cools the electronic components in the handle, and then directly enters the inner housing through the air inlet 37 above the handle, and flows over the motor 4 under the action of the fan 8. Therefore, the air intake channel has an optimal aerodynamic path.

[0047] exist Figure 1 , Figure 2 and Figure 6 In the illustrated embodiment, the second end 22 of the outer housing 2 is closed, i.e., the outer housing 2 includes a closed rear end face 25. In this case, preferably, the position of the air outlet 38 on the inner housing 3 is substantially aligned with the position of the exhaust port 28 on the outer housing 2; therefore, the exhaust, which has cooled the electronic components and motor and has been heated, is discharged directly along the shortest path, thus not affecting the relatively cold airflow in the intake passage.

[0048] However, the second end of the outer casing 2 may not be closed, or may even be completely open; for example, in Figures 3 to 5 In the impact wrench shown, the outer housing 2 surrounds the inner housing 3 only in the axial direction. The outer housing 2 and the inner housing 3 have substantially the same length in the axial direction, or the axial length of the outer housing 2 is slightly less than that of the inner housing 3, and the second end face 25 of the inner housing protrudes slightly rearward beyond the second end 22 of the outer housing. This helps to reduce the overall length of the tool. Furthermore, the open second end 22 can generally be used as a vent, eliminating the need for an additional vent.

[0049] Many types of materials can be used for the insulating element. Preferably, the insulating element is formed of a non-metallic material capable of elastic deformation. More preferably, the insulating element is formed of polyurethane foam. Polyurethane foam has sufficient strength, good abrasion resistance and UV resistance, and also has the same service life as the inner and outer shells formed of plastic, thus making it an ideal elastic insulating element of the present invention. Of course, the material, density, or thickness of the insulating element, etc., are appropriately varied according to the intensity required to attenuate the impact vibrations transmitted from the internal sub-assemblies.

[0050] As described above, although exemplary embodiments of the invention have been explained herein with reference to the accompanying drawings, the invention is not limited to the specific embodiments described above, and may have many other embodiments. The scope of the invention should be defined by the claims and their equivalents.

Claims

1. A rotary impact tool, comprising: An outer casing and an inner casing that is at least partially surrounded by the outer casing; A motor and an impact mechanism, the motor being mounted within the internal housing, the impact mechanism being connected to the motor and fixedly mounted to the internal housing, defining an integrated internal subassembly including the motor and the impact mechanism; characterized in that... At least one resilient isolation element is disposed between the outer housing and the inner housing and extends circumferentially around the inner housing, such that the inner subassembly is resiliently isolated from the outer housing.

2. The rotary impact tool according to claim 1, characterized in that, The inner housing is substantially cylindrical, having a first end that opens forward and a second end that closes backward. The motor is mounted in the inner housing on the side near the second end. The impact mechanism is fixedly mounted to the first end of the inner housing. The outer housing has substantially the same shape as the inner housing in the axial direction, and the inner surface of the outer housing has a larger diameter than the outer surface of the inner housing. Support is provided solely by the insulating element between the outer housing and the inner housing.

3. The rotary impact tool according to claim 2, characterized in that, The isolation element includes a first isolation element and a second isolation element, which surround the circumferential outer surfaces of a first end and a second end of the inner housing, respectively.

4. The rotary impact tool according to claim 3, characterized in that, The outer surface of the inner housing and the inner surface of the outer housing are respectively provided with a first positioning structure and a second positioning structure. The first isolation element is received in the first positioning structure and the second isolation element is received in the second positioning structure.

5. The rotary impact tool according to claim 4, characterized in that, The handle extends below the outer housing, and the power supply is connected to the lower end of the handle. The electronic components that connect the power supply and the motor are housed in the handle.

6. The rotary impact tool according to claim 5, characterized in that, An air inlet for drawing in external air is provided on the handle or on the outer housing between the first positioning structure and the second positioning structure. The outer housing is provided with an exhaust port further back than the second positioning structure. An air inlet is provided in the portion of the inner housing between the two isolation elements. The inner housing is provided with an air outlet further back than the second positioning structure.

7. The rotary impact tool according to claim 6, characterized in that, The motor includes a fan located at the rear of the motor and a drive shaft located at the front of the motor, and the air inlet is located on the inner housing at a position corresponding to the drive shaft and facing the handle.

8. The rotary impact tool according to claim 7, characterized in that, The location of the air outlet on the inner housing is substantially opposite to the location of the exhaust port on the outer housing.

9. The rotary impact tool according to claim 1, characterized in that, The isolation element comprises a uniform, continuous annular shape.

10. The rotary impact tool according to claim 1, characterized in that, The isolation element includes an annular shape having a shape-fitting portion in the circumferential direction.

11. The rotary impact tool according to claim 9 or 10, characterized in that, The isolation element further includes axially extending protrusions that are discretely distributed in the circumferential direction of the annular shape.

12. The rotary impact tool according to any one of claims 2 to 11, characterized in that, The rearward second end of the outer housing is not closed, and the outer housing only surrounds the inner housing in the axial direction.

13. The rotary impact tool according to any one of claims 2 to 11, characterized in that, The rearward second end of the outer housing is closed and has a rear end face that is substantially perpendicular to the axial direction, and a third elastic isolation element is provided between the rear end face of the outer housing and the second end face formed at the closed second end of the inner housing.

14. The rotary impact tool according to any one of the preceding claims, characterized in that, The insulating element is formed of polyurethane foam.

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