Ambidextrous switch lockout system

Details Ambidextrous switch lockout system Ambidextrous switch lockout system

2002-10-16

2004-06-22

Mai, Anh (Department: 2832)

Electricity: circuit makers and breakers

Electric switch details

Latches

C200S318000, C200S518000, C200S043160

Reexamination Certificate

active

06753490

ABSTRACT:

FIELD OF THE INVENTION
This invention generally relates to safety lockout switches, and more particularly, to an ambidextrous switch lockout system.
BACKGROUND OF THE INVENTION
Some power saws, such as miter saws, have safety lockout buttons that require actuation before a power switch can be turned to the on position. Safety lockout buttons effectively minimize the probability of accidental tool activation by requiring the user to follow a sequence of at least two steps before activation.
Conventional lockout buttons are spring-loaded and include an internal blocking feature that mechanically interferes with the travel of a power switch trigger or lever. After the power switch is released to an off position, the system resets, and again requires at least two steps before the tool can be activated again.
Some conventional safety lockout systems include a removable button with a hole for receiving the button. When the removable button is not in place in the hole, the tool cannot be powered up. The removable button is intended to decrease the probability for accidental tool activation by adding an additional step to the process used for activating the tool. However, the removable button is an inconvenience if lost. A lost removable button can be more than an inconvenience, and may present a safety problem, for example, if users force other items into the hole to replace the lost removable button.
Power saws with vertical handles may also have a lockout button protruding from a left side of the handle, near the switch trigger. This conventional system is not ambidextrous. When used with a right hand, the lockout button is actuated by a thumb and the switch trigger by an index finger. When used with a left hand, the lockout button and switch trigger are usually both actuated by an index finger of the left hand.
The invention disclosed by U.S. Pat. No. 5,969,312 to Svetlik et al. (“the '312 patent”) is for an ambidextrous lockout switch. Although the lockout switch of the '312 patent can be operated by both a left handed user and a right handed user, and is in this sense “ambidextrous”, the method for using the ambidextrous lockout switch of the '312 patent is substantially different for a right handed user than for a left handed user, and is not truly ambidextrous in this sense. In particular, a left handed user must rely on a “slide switch 22”, whereas a right handed user activates a “pressure button 23” for actuation.
There is, therefore, a need in the art for a switch lockout system that is convenient for use by both left and right handed users, and is actuatable in a substantially similar way by both left and right handed users.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a generally balanced ambidextrous switch lockout system, actuatable in the same way by both left handed and right handed users. On a horizontally oriented handle, left handed and right handed users perform substantially the same steps to activate the power. The left side lockout button is identical to the right side lockout button in appearance and function. In the system of the present invention, both the left handed and right handed users press the right and left lockout buttons, respectively, with a thumb. The system of the present invention resets automatically after a switch lever or trigger is released. The system of the present invention may be added to a multi-position handle, which can be selectively oriented in a plurality of positions, including both horizontal and vertical positions. The present invention is ambidextrous, i.e., suitable for use by both left handed and right handed users, in any of the plurality of positions.
In a first embodiment, the present invention generally includes: a left lockout button, a right lockout button, a linkage, a centering spring, and a switch lever. The left lockout button is pivotally mounted to the left side of a horizontal handle with a protrusion from the left side of the handle. The protrusion on the left side of the handle is intended for thumb actuation by the right hand of a user when the handle is in a generally horizontal position. On a rotatable handle, when the handle is in a generally vertical position, the left lockout button is on top, and the one left lockout button may be activated by either a left handed user or a right handed user in substantially the same way. The left lockout button includes a barrier intended to stop actuation of the switch lever. The left lockout button has an aperture spaced apart from where the left lockout button is pivotally mounted. The aperture allows for a hinged connection to the linkage between the left lockout button and the right lockout button. The left lockout button also has two fingers that contact opposite ends of a centering spring.
The right lockout button is substantially a mirror image of the left lockout button, but without the barrier or the two fingers for contacting a centering spring. The thumb of the left hand of a user presses a protrusion from the right side of the handle. The right lockout button also has an aperture for mechanical coupling (through the linkage) between the left lockout button and the right lockout button. With both left and right lockout buttons mounted to the handle and the linkage connecting them, pressing the left lockout button causes the protrusion of the right lockout button to move leftwardly, and pressing the right lockout button causes the protrusion of the left lockout button to move rightwardly.
The centering spring is mounted to the handle in a spring mount, which holds a first and a second end of the spring. The spring mount is under the left lockout button, and has left and right ends, with interruptions in both left and right ends to allow the two fingers of the left lockout button to penetrate as the left lockout button moves. Pressing on the left lockout button causes the right finger to compress the centering spring to the left. Because of the linkage, pressing down on the right lockout button causes the left finger to compress the centering spring to the right. When neither the left lockout button nor the right lockout button has been pressed, both are held by the centering spring at a blocking position. At the blocking position, the barrier of the left lockout button blocks movement of the switch lever, preventing actuation of the switch lever. When the left lockout button is pressed, the barrier moves leftwardly, outside the switch lever, and allows the switch lever to be actuated. When the operably linked right lockout button is pressed, the barrier of the left lockout button moves rightwardly, inside the switch lever, and allows the switch lever to be actuated by an inward movement.
In a first embodiment, the present invention includes an ambidextrous lockout switch including a handle body with a first side and a second side, a switch, a barrier, a first lockout button, a second lockout button, and a spring. The switch is mounted to the handle body, and extends outwardly from the handle body. The switch can be actuated by an activating movement, which might be an inward, squeezing movement The barrier is mounted inside the handle body, and is movable from a blocking position in which the activating movement of the switch is blocked. The first lockout button is movably mounted to the handle body, and is adapted for moving the barrier in and out of the blocking position. Operably linked to the first lockout button is the second lockout button, with the second lockout button also adapted for moving the barrier in and out of the blocking position. The spring, which is mounted inside the handle body, is mechanically coupled to the barrier, and biases the barrier toward the blocking position when the barrier has been moved away from the blocking position by either the left lockout button or the right lockout button.
Optionally, the barrier and the switch may have complementary surfaces, which are shaped to maximize surface contact between the barrier and the switch when the barrier is in the blocking position. The switch may h

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