CA-3140824-C - IMPACT MECHANISM FOR A ROTARY IMPACT TOOL

Abstract

An impact mechanism for a rotary impact tool including a centering component, a gear carrier adapted to receive rotational force from the motor and including a gear carrier aperture adapted to receive the centering component, an anvil rotatable about the central axis and including an impact section and an anvil aperture adapted to receive the centering component, and a hammer slidably coupled to the gear carrier, rotatable about a central axis, and defining a planar surface, the hammer including a lug extending from the planar surface. The centering component functions as a pilot between the gear carrier and anvil. The centering component can include an axial bore. Axial clearance and a slip-fit can be provided between the gear carrier and the centering component and between the anvil and the dowel to allow the hollow dowel to move axially.

Inventors

• Collin T. Kohls
• Adrian J. Robillard

Assignees

• SNAP-ON INCORPORATED

Dates

Publication Date

20260505

Application Date

20211201

Priority Date

20201208

Claims (15)

1. CLAIMS What is claimed is: 1. An impact mechanism for an impact tool, comprising: a gear carrier including a gear carrier aperture extending into the gear carrier and terminating at a first end wall; an anvil rotatable about an axis and including an impact section and an anvil aperture extending into the anvil and terminating at a second end wall; a centering component including opposing first and second ends respectively slidably received in the gear carrier aperture and the anvil aperture, wherein the centering component is disposed between the first and second end walls, and the first and second ends of the centering component respectively face the first and second end walls, and in substantially opposite directions, thereby radially aligning and coupling die gear carrier and the anvil; and a hammer slidably coupled to the gear carrier, rotatable about die axis, and including a planar surface with a lug extending therefrom.
2. 2. The impact mechanism of claim 1, wherein the centering component includes an axial bore.
3. 3. The impact mechanism of claim 1, wherein the centering component is slidably received in the gear carrier aperture and the anvil aperture using a slip-fit tolerance.
4. 4. The impact mechanism of claim 1, wherein a first axial clearance is provided between die first end and the first end wall and a second axial clearance is provided between the second end and the second end wall.
5. 5. The impact mechanism of claim 1, wherein the gear carrier includes a through hole. 11
6. 6. The impact mechanism of claim 1, further comprising a ball that engages a ball groove disposed on the hammer and a circumferential groove disposed on the gear carrier.
7. 7. The impact mechanism of claim 1, wherein die anvil includes an output drive.
8. 8. An impact tool comprising: a motor; and an impact mechanism including: a gear carrier adapted to receive rotational force from the motor and including a gear carrier aperture extending into the gear carrier and terminating at a first end wall; an anvil rotatable about an axis and including an impact section and an anvil aperture extending into die anvil and terminating at a second end wall; a centering component including opposing first and second ends respectively slidably received in the gear carrier aperture and the anvil aperture, wherein the centering component is disposed between the first and second end walls, and the first and second ends of the centering component respectively face die first and second end walls, and in substantially opposite directions, thereby radially aligning and coupling the gear carrier and the anvil; and a hammer slidably coupled to the gear carrier, rotatable about the axis, and including a planar surface with a lug extending therefrom.
9. 9. The impact tool of claim 8, wherein die impact tool is an impact driver.
10. 10. The impact tool of claim 8, wherein the centering component includes an axial bore.
11. 11. The impact tool of claim 8, wherein the centering component is slidably received in the gear carrier aperture and the anvil aperture using a slip-fit tolerance. 12
12. 12. The impact tool of claim 8, wherein a first axial clearance is provided between the first end and the first end wall and a second axial clearance is provided between the second end and the second end wall.
13. 13. The impact tool of claim 8, wherein the gear carrier includes a through hole.
14. 14. The impact tool of claim 8. further comprising a ball disposed in a ball groove of the hammer and a circumferential groove of the gear carrier.
15. 15. The impact tool of claim 8, wherein the anvil is coupled to an output drive.

Description

IMPACT MECHANISM FOR A ROTARY IMPACT TOOL 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 [0002] A variety of tools are commonly used to apply torque to a workpiece, such as a threaded fastener. One such tool, known as an impact driver or tool, which is commonly used to remove fasteners, such as, for example, lug nuts on a vehicle wheels. Often, the fasteners, such as lug nuts, are corroded or otherwise difficult to remove. An impact driver eases such removal. [0003] The impact driver is designed to deliver high torque output by storing energy in a rotating mass, then delivering it suddenly in a repetitive impacting fashion to the output shaft. In operation, a rotating mass, known as a hammer, is accelerated by a gear carrier coupled to a motor, storing energy, then suddenly connected to the output shaft, the anvil, creating a hightorque impact. The hammer mechanism is designed such that after delivering the impact, the hammer is again allowed to spin freely from the anvil. As such the only reaction force applied to the body of the tool is the motor accelerating the hammer, and thus the operator feels very little torque, even though a very high peak torque is delivered to the output shaft. The traditional hammer design requires a certain minimum torque before the hammer is allowed to spin separately from the anvil, causing the tool to stop hammering and instead smoothly drive the fastener if only low torque is needed, thereby rapidly rotating the fastener. [0004] Traditional impact tools include a gear carrier having a protrusion, also referred to as a pilot, adapted to center the gear carrier and the anvil. This results in a stress concentration at a transition radius as the gear carrier transitions from a larger to a smaller diameter at the 1 Date ReQue/Date Received 2022-03-22protrusion. Accordingly, cyclical bending loads imparted on the protrusion during repeated use of the tool eventually causes failure at the transition radius. [0005] Typical impact tools use extra processing (such as, for example, shot peening) of the protrusion, larger diameter protrusions, shorter protrusion lengths, constructing the protrusion out of stronger material, 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 protrusion inevitably fails. SUMMARY [0006] The present invention relates broadly to an impact mechanism for a rotary impact tool, such as an impact driver that is powered by a fluid, such as air or hydraulic fluid, or by electricity via an external power source (such as a wall outlet and/or generator outlet) or a battery. The impact mechanism has a separate centering component, such as a dowel, that radially aligns the gear carrier and anvil. The centering component eliminates the need for the gear carrier to have a conventional protrusion (pilot), so there are no stress concentrations as the gear carrier transitions from a large to a small diameter. The impact mechanism of the present invention further allows for replacement of only the centering component without requiring the removal and/or replacement of the gear carrier. [0007] In an embodiment, the present invention broadly comprises 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 section and an anvil aperture, a centering component slidably received in the gear carrier aperture and the anvil aperture, thereby radially aligning and coupling the gear carrier and anvil, and a hammer slidably coupled to the gear 2 Date ReQue/Date Received 2022-03-22carrier and is rotatable about the axis and includes a planar surface with a lug extending therefrom. [0008] In another embodiment, the present invention broadly comprises an impact tool including a motor and an impact mechanism. The impact mechanism includes a gear carrier adapted to receive 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 component slidably received in the gear carrier aperture and the anvil aperture, thereby radially aligning and coupling the gear carrier and anvil, and a hammer slidably coupled to the gear carrier and is rotatable about the axis and includes a planar surface with a lug extending therefrom. BRIEF DESCRIPTION OF THE DRAWINGS [0009] For the purpose of facilitating an understanding of the subject matter sought to be protected, there are illustrated in the accompanying drawings embodiments thereof, from an inspection of which, when considered in connection with the following description, the subject matter sought to be protected, its construction and operation, and many of its advan