Impact mechanism for rotary impact tool

Abstract

The present invention discloses an impact mechanism for a rotary impact tool, comprising: a centering component; a gear frame, which is suitable for receiving a rotational force from a motor and includes a gear frame aperture suitable for accommodating the centering component; an anvil, which is rotatable around a central axis and includes an impact section and an anvil aperture suitable for accommodating the centering component; and a hammer, which is slidably connected to the gear frame, rotatable around a central axis and defines a flat surface, the hammer including a lug extending from the flat surface. The centering component serves as a guide between the gear frame and the anvil. The centering component may include an axial hole. Axial clearance and a sliding fit may be provided between the gear frame and the centering component and between the anvil and the pin to allow the hollow pin to move axially.

Description

Technical Field

[0001] The present application relates generally to tools for driving fasteners and, more particularly, to an impact mechanism for a rotary impact tool. Background Art

[0002] Various tools are commonly used to apply torque to a workpiece, such as a threaded fastener. One such tool, called an impact driver or tool, is commonly used to remove fasteners, such as lug nuts on a wheel. Fasteners, such as lug nuts, are often corroded or difficult to remove. An impact driver facilitates such removal.

[0003] Impact drivers are designed to deliver high torque output by storing energy in a rotating mass and then suddenly transferring the energy to the output shaft in a repeated impact manner. In operation, the rotating mass (called a hammer) is accelerated by a gear rack connected to a motor, stores energy, and then suddenly connected to the output shaft (anvil), producing a high torque impact. The hammer mechanism is designed so that after the impact is transmitted, the hammer is allowed to spin freely away from the anvil again. It can be seen that the only reaction force applied to the tool body is the motor that accelerates the hammer, so even if a very high peak torque is transmitted to the output shaft, the operator feels very little torque. Traditional hammer designs require a certain minimum torque before allowing the hammer to spin apart from the anvil, which prompts the tool to stop hammering and, on the contrary, smoothly drive the fastener when only a lower torque is required, thereby quickly rotating the fastener.

[0004] Conventional impact tools include a gear carrier having a protrusion, also called a guide, adapted to center the gear carrier and the anvil. This results in stress concentration at the transition radius when the gear carrier transitions from a larger diameter to a smaller diameter at the protrusion. Therefore, the cyclic bending loads imposed on the protrusion during repeated use of the tool eventually lead to failure at the transition radius.

[0005] Typical impact tools use additional treatment of the projections (e.g., shot peening), larger diameter projections, shorter projection lengths, constructing the projections from stronger materials, and / or utilizing heat treatment processes to increase ultimate strength and fatigue strength. However, these solutions still require replacement of the entire gear carrier when the projections inevitably fail. Summary of the invention

[0006] The present invention broadly relates to an impact mechanism for a rotary impact tool, such as an impact driver powered by a fluid (e.g., air or hydraulic fluid) or by electricity via an external power source (e.g., a wall outlet and / or a generator outlet) or a battery. The impact mechanism has a separate centering component (e.g., a pin) that radially aligns the gear carrier and the anvil. The centering component eliminates the need for the gear carrier to have a traditional protrusion (guide) so that there is no stress concentration when the gear carrier transitions from a large diameter to a small diameter. The impact mechanism of the present invention also allows only the centering component to be replaced without removing and / or replacing the gear carrier.

[0007] In one embodiment, the invention broadly includes an impact mechanism for an impact tool. The impact mechanism includes: a gear carrier including a gear carrier aperture; an anvil rotatable about an axis and including an impact segment and an anvil aperture; a centering member slidably received in the gear carrier aperture and the anvil aperture to radially align and couple the gear carrier and the anvil; and a hammer slidably coupled to the gear carrier and rotatable about the axis and including a flat surface having a lug extending therefrom.

[0008] In another embodiment, the present invention broadly includes an impact tool including a motor and an impact mechanism. The impact mechanism includes: a gear carrier adapted to receive a rotational force from the motor and including a gear carrier aperture; an anvil rotatable about an axis and including an impact section and an anvil aperture; a centering member slidably received in the gear carrier aperture and the anvil aperture to radially align and couple the gear carrier and the anvil; and a hammer slidably coupled to the gear carrier and rotatable about the axis and including a flat surface having a lug extending therefrom. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] To facilitate understanding of the subject matter for which protection is sought, embodiments thereof are illustrated in the accompanying drawings and, when considered in conjunction with the following description, the subject matter for which protection is sought, its construction and operation, and its many advantages should be readily understood and appreciated from an inspection of the embodiments thereof.

[0010] Figure 1 is a perspective view of an impact tool according to an embodiment of the present invention.

[0011] Figure 2 is a perspective view of an impact mechanism according to an embodiment of the present invention.

[0012] Figure 3 It is along Figure 2 The line 3-3 is intercepted Figure 2 A cross-sectional view of the impact mechanism.

[0013] Figure 4 is a perspective view of an impact mechanism according to another embodiment of the present invention.

[0014] Figure 5 It is along Figure 4 The line 5-5 is intercepted Figure 4 A cross-sectional view of the impact mechanism. DETAILED DESCRIPTION

[0015] Although the present invention is susceptible of many different forms of embodiments, preferred embodiments of the present invention are shown in the drawings and will be described in detail herein, it should be understood that the present invention should be considered as an example of the principles of the present invention and is not intended to limit the broad aspects of the present invention to the illustrated embodiments. As used herein, the term "present invention" is not intended to limit the scope of the claimed invention, but is only a term used to discuss exemplary embodiments of the present invention for the purpose of explanation.

[0016] The present invention broadly includes an impact mechanism for a rotary impact tool. The impact mechanism includes a centering component (e.g., a pin, a gear carrier, and an anvil). The centering component radially aligns and centers the gear carrier and the anvil. In one embodiment, an axial clearance and a sliding fit tolerance are provided between the gear carrier and the centering component and / or between the anvil and the centering component to allow axial movement of the centering component to minimize cyclic bending loads applied to the same location on the centering component due to repeated use of the tool.

[0017] refer to Figures 1 to 3 , an impact tool 100 (e.g., an impact driver) has a housing 102 including a handle portion 104 and a motor housing portion 106. A motor (not shown) and an impact mechanism 108 are disposed in the motor housing portion 106. The impact mechanism 108 may include or be coupled to an output driver 110, all in a known manner. A trigger 112 for controlling the operation of the impact tool 100 is disposed on the handle portion 104, adjacent to the motor housing portion 106. Depressing the trigger 112 causes the output driver 110 to rotate in a clockwise or counterclockwise direction. A suitable tool, such as a socket, may be coupled to the output driver 110 to interface with an associated fastener, etc., to which torque is to be applied. In one embodiment, the impact tool 100 is powered by a battery (not shown), which is removably mounted at a battery interface 114 of the handle portion 104. In another embodiment, the impact tool 100 is powered by a fluid, such as a hydraulic fluid or air.

[0018] The impact mechanism 108 includes a hammer 116, anvil 118, gear carrier 120 and centering member 122. A sliding fit tolerance can be achieved between gear carrier 120 and centering member 122 and / or between anvil 118 and centering member 122. This allows the hammer 116 and anvil 118 to spin relative to each other when a minimum torque is reached. This also allows the interface to slide rotationally with a minimum amount of friction (optimal lubrication).

[0019] The hammer 116 includes a flat surface 124 rotatable about a central axis and one or more hammer lugs 126 extending from the flat surface 124. The hammer 116 is slidably coupled to the gear frame 120, which is adapted to receive a rotational force from a motor. In one embodiment, the hammer 116 includes an aperture 128 adapted to accommodate the gear frame 120. The hammer aperture 128 includes a ball groove 130 adapted to accommodate one or more balls 132. The hammer 116 also includes a biasing member groove 134 adapted to accommodate a biasing member (not shown). The biasing member may be, for example, a spring, and is adapted to apply a biasing force to bias the hammer 116 axially toward the anvil 118.

[0020] The anvil 118 includes one or more impact segments 136 extending from the central axis. The anvil also includes or is coupled to the output driver 110, to which a tool such as a sleeve may be directly or indirectly attached. The impact segment 136 is adapted to receive an impact force from the hammer lug 126 to drive the output driver 110. The anvil 118 also includes an anvil aperture 138 adapted to receive the centering member 122.

[0021] The gear carrier 120 is adapted to receive the rotational force from the motor and transmit the rotational force to the hammer 116. The gear carrier 120 includes a gear carrier aperture 140 adapted to accommodate the centering member 122. In one embodiment (not shown), the gear carrier 120 includes a through hole to allow ventilation and facilitate removal of the centering member 122. The gear carrier 120 may include a circumferential groove 142 adapted to accommodate the ball 132, and the circumferential groove 142 and the ball groove 130 are adapted to axially move the hammer 116 away from the anvil 118 when the minimum torque is reached, as discussed in more detail below.

[0022] The centering member 122 is disposed in the anvil aperture 138 and the gear carrier aperture 140 to radially align the gear carrier 120 and the anvil 118. The centering member 122 can be slidably received by the anvil aperture 138 and / or the gear carrier aperture 140 with a sliding fit tolerance. The centering member 122 can be, for example, a dowel pin. The centering member 122 can be made of a different material or a different grade of steel, which does not necessarily have the same properties as required for other locations on the gear carrier 120. In one embodiment, the centering member 122 has different properties than the gear carrier 120 (e.g., a higher strength material that may be too brittle for other locations on the gear carrier). In another embodiment, only the centering member 122 undergoes a cold working process (e.g., shot peening). This saves additional processing and costs in manufacturing the gear carrier 120.

[0023] The carrier aperture 140 and the anvil aperture 138 are sized to provide axial clearance between a first end of the centering member 122 and a first end wall 144 of the carrier aperture 140 and / or between a second end of the centering member 122 and a second end wall 146 of the anvil aperture 138. By providing axial clearance between the centering member 122 and the anvil 118 and between the centering member 122 and the carrier 120, the centering member 122 is adapted to be axially movable relative to the anvil 118 and the carrier 120. This axial movement allows the centering member 122 to be subjected to stress at different locations along its length during operation of the impact tool 100, thereby limiting fatigue by not repeating stress at the same location.

[0024] During use of the impact tool 100 (i.e., when the operator actuates the trigger 112), the motor drives the hammer 116 and the gear carrier 120 in either a clockwise or counterclockwise direction, which causes the hammer lug 126 to contact the impact segment 136 to drive the anvil 118 and the output driver 110 in the desired clockwise or counterclockwise direction. Once the torque required to drive the output driver 110 exceeds the minimum torque, the gear carrier 120 rotates at a faster speed than the hammer 116 and the anvil 118, causing the ball 132 to move back and forth along the ball groove 130 and the circumferential groove 142. As the ball 132 moves back and forth along the ball groove 130 and the circumferential groove 142, the hammer 116 overcomes the biasing force applied by the biasing member and moves axially away from the anvil 118 until the hammer lug 126 no longer contacts the impact segment 136. Once the hammer lugs 126 no longer contact the impact segment 136 , the biasing member urges the hammer 116 to move axially toward the anvil 118 and transmit a sudden rotational impact force to the anvil 118 , and thus to the output driver 110 .

[0025] In another embodiment, if Figure 4 and Figure 5 As shown, the impact mechanism 208 (generally similar to the impact mechanism 108 described above) includes a hammer 216, anvil 218, gear carrier 220 and centering member 222 (generally similar to the hammer 116, anvil 118, gear carrier 120 and centering member 122 described above, except that the centering member 222 includes an axial hole 248, as shown in FIG. Figure 5 shown).

[0026] Similar to the hammer 116 described above, the hammer 216 includes a flat surface 224 rotatable about a central axis and one or more hammer lugs 226 extending from the flat surface 224. The hammer 216 is slidably coupled to the gear frame 220, which is adapted to receive a rotational force from the motor. In this embodiment, the hammer 216 includes an aperture 228 adapted to accommodate the gear frame 220. Similar to the hammer aperture 128 described above, the hammer aperture 228 includes a ball groove 230 adapted to accommodate one or more balls 232, the balls 232 and the ball 230 grooves generally corresponding to the ball grooves 130 and balls 132 described above. The hammer 216 also includes a biasing member groove 234, which is generally similar to the biasing member groove 134 described above, adapted to accommodate a biasing member (not shown). The biasing member may be, for example, a spring, and is adapted to apply a biasing force to bias the hammer 216 axially toward the anvil 218.

[0027] Similar to the anvil 118 described above, the anvil 218 includes one or more impact segments 236 extending from the central axis, which generally correspond to the one or more impact segments 136 described above. Similar to the anvil 118 described above, the anvil 218 also includes or is coupled to an output driver 210, which generally corresponds to the output driver 110 described above. Similar to the anvil 118 described above, the anvil 218 also includes an anvil aperture 238, which generally corresponds to the anvil aperture 138 described above, suitable for receiving the centering member 222.

[0028] Similar to the above-described carrier 120, the carrier 220 includes a carrier aperture 240, which generally corresponds to the above-described carrier aperture 140, adapted to receive the centering member 222. Similar to the above-described carrier 120, the carrier 220 may include a circumferential groove 242, which generally corresponds to the above-described circumferential groove 142, adapted to receive the ball 232.

[0029] In this embodiment, the centering member 222 includes an axial hole 248. Similar to the centering member 122 described above, the centering member 222 is disposed in the anvil aperture 238 and the gear carrier aperture 240 to radially align the gear carrier 220 and the anvil 218. The centering member 222 can be slidably received by the anvil aperture 238 and / or the gear carrier aperture 240 with a sliding fit tolerance. Similar to the centering member 122 described above, the centering member 222 can be, for example, a locating pin.

[0030] In the present embodiment, the axial bore 248 in the centering member 222 exhausts air or gas trapped within the anvil aperture 238 and / or the carrier aperture 240. Additionally, the axial bore 244 allows lubrication to be applied to the tight fit interface between the centering member 222 and the anvil aperture 238. Similar to the centering member 122 described above, a sliding fit tolerance can be achieved between the carrier 220 and the centering member 222 and / or between the anvil 218 and the centering member 222. This allows the hammer 216 and the anvil 218 to spin relative to each other when a minimum torque is reached. This also allows the interface to rotationally slide with a minimum amount of friction (optimal lubrication).

[0031] As used herein, the term "coupled" and its functional equivalents are not intended to be necessarily limited to a direct mechanical coupling of two or more components. Rather, the term "coupled" and its functional equivalents are intended to mean any direct or indirect mechanical, electrical, or chemical connection between two or more objects, features, workpieces, and / or environmental materials. In some examples, "coupled" is also intended to mean that one object is integral with another object.

[0032] The contents set forth in the above description and the accompanying drawings are provided by way of illustration only and not by way of limitation. Although specific embodiments have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made without departing from the broader aspects of the inventor's contribution. The actual scope of protection sought is intended to be defined by the appended claims when viewed in appropriate perspective based on the prior art.

Claims

1. An impact mechanism for an impact tool, comprising: a gear carrier including a gear carrier blind bore formed by a gear carrier aperture extending into the gear carrier and terminating at a first end wall within the gear carrier; an anvil rotatable about an axis and including an impact segment and an anvil blind bore formed by an anvil aperture extending into the anvil and terminating at a second end wall within the anvil; a centering member including opposed first and second ends and an axial bore, wherein the centering member is disposed between the first end wall and the second end wall, and the first end and the second end are slidably received in the carrier blind hole and the anvil blind hole, respectively, to radially align and couple the carrier and the anvil; as well as A hammer is slidably coupled to the carrier and is rotatable about an axis and includes a planar surface having a lug extending therefrom.

2. The impact mechanism according to claim 1, characterized in that: The centering member is slidably received in the carrier blind hole and the anvil blind hole with a sliding fit tolerance.

3. The impact mechanism according to claim 1, characterized in that: A first axial gap is provided between the first end and the first end wall of the carrier, and a second axial gap is provided between the second end and the second end wall of the anvil.

4. The impact mechanism according to claim 1, characterized in that: The gear carrier includes a through hole.

5. The impact mechanism according to claim 1, characterized in that: Also included are balls that engage with a ball groove disposed on the hammer and a circumferential groove disposed on the gear carrier.

6. The impact mechanism according to claim 1, characterized in that: The anvil includes an output drive.

7. An impact tool comprising: motor; and Impact mechanism, including: a gear carrier adapted to receive rotational force from the motor and including a gear carrier blind hole formed by a gear carrier aperture extending into the gear carrier and terminating at a first end wall within the gear carrier; an anvil rotatable about an axis and including an impact segment and an anvil blind bore formed by an anvil aperture extending into the anvil and terminating at a second end wall within the anvil; a centering member including opposed first and second ends and an axial bore, wherein the centering member is disposed between the first end wall and the second end wall, and the first end and the second end are slidably received in the carrier blind hole and the anvil blind hole, respectively, to radially align and couple the carrier and the anvil; and A hammer is slidably coupled to the carrier and is rotatable about an axis and includes a planar surface having a lug extending therefrom.

8. The impact tool according to claim 7, characterized in that The impact tool is an impact driver.

9. The impact tool according to claim 7, characterized in that The centering member is slidably received in the carrier blind hole and the anvil blind hole with a sliding fit tolerance.

10. The impact tool according to claim 7, characterized in that A first axial gap is provided between the first end and the first end wall of the carrier, and a second axial gap is provided between the second end and the second end wall of the anvil.

11. The impact tool according to claim 7, characterized in that The gear carrier includes a through hole.

12. The impact tool according to claim 7, characterized in that Also included are balls, which are arranged in the ball grooves of the hammer and the circumferential grooves of the gear carrier.

13. The impact tool according to claim 7, characterized in that The anvil is coupled to an output driver.

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