Patent Application
20090104861
The present invention relates to power hand tools and more particularly to a handle assembly of the type used for holding, activating and deactivating a power hand tool. The handle assembly of the present invention is particularly suitable for use in relation to a hand held power angle grinder and is discussed below in this context.
Hand held power angle grinders have an electric motor driving a driven member that grips a working element, such as an abrasive disc, for performing work on a workpiece. There are a myriad of different discs that are used for various materials and tasks, such as cutting discs, buffing pads and saws, each of which can be renewed when worn or switched when required. The angle grinder has large bearings to counter side forces generated during cutting, unlike a power drill where the force is axial. Used widely in Engineering, in particular metalworking and construction, as well as in emergency rescues, hand held power angle grinders can be very dangerous due to the high rpm involved and the sparks that fly off as they cut. Safety equipment is usually worn while using these power tools to avoid injury.
Hand held power angle grinders can have an electric motor, a pneumatic drive or an internal combustion motor for driving the driven member in a circular motion that in turn causes the working element to rotate. In each case a hand held power angle grinder will include a switch assembly that is operable by the hand of a user for activating the motor when the grinder is in use. Grinders that have electric motors will usually also have an electric power lead having a plug at one end that is adapted to be received in a power socket while the other end enters the grinder housing. The power lead connects to a switch assembly within the grinder housing. Alternatively, grinders may have an on-board energy storage device, such as a battery, connected to the switch assembly rather than an electric power lead connected to a power socket. The switch assembly is operable by hand to complete an electrical circuit with the grinder's electric motor. Current flows through the completed circuit and through the motor to drive the driven member and rotate the working element. The switch assembly is also operable by hand to break the circuit and cut the flow of current to the motor when the grinder is not in use.
Existing switch assemblies that are incorporated into hand held power angle grinders include an elongate trigger that is operable by hand to actuate a switch mechanism between an off position where the circuit is broken and no current flows to the motor and an on position where the circuit is completed and current flows through the motor. The elongate trigger is generally attached to the housing of a grinder and oriented lengthwise with and protruding from the housing. The trigger is designed so that a user's hand wraps around the housing and the fingers engage the elongate trigger and squeeze the trigger into the housing.
Existing switch assemblies include, as a safety feature, two separate pivot points that enable the elongate trigger to move through two travel paths so that the grinder cannot be inadvertently activated if the grinder is picked up or dropped. In fact, in some countries, such a feature is mandated by law. The first path of movement is longitudinal such that when a user operates the trigger by hand the trigger is moved firstly through a longitudinal motion that is usually lengthwise along the grinder housing. After the trigger has moved through the first path it can then move through the second path of motion. The second path is a pivoting motion. The pivoting motion involves the trigger pivoting about a point of attachment of the trigger with the housing of the grinder. The point of attachment on the trigger, which is also the point about which the trigger pivots, is located at an end of the trigger in the direction from where the trigger moved longitudinally in the first path of motion. Thus, the leading end of the trigger in the direction of longitudinal travel is also the end that pivots in an arc in the second path of motion. This end is squeezed by hand into the housing in the second path of motion. This causes a protrusion on the lever to engage the switch and place it in the on position where current flows to the motor.
To enable a user to move the trigger through the two paths of motion the trigger has a flange at the opposite end to the point of attachment of the trigger about which it pivots. The user's hand grips around the elongate portion of the trigger such that the user's hand can abut against the flange and slide the trigger longitudinally through the first path and then pivot the trigger about the pivot point through the second path by squeezing the trigger inwardly towards the grinder housing. The switch assembly includes biasing means that bias the trigger into a resting position that corresponds to the position of the trigger before it is moved through the first path of motion. Thus when the trigger is released, the protrusion on the trigger disengages the switch so that the switch reverts to the off position where current does not flow to the motor.
Existing switch assemblies such as those mentioned above are used in relation to hand held power angle grinders. Nonetheless, there are problems that arise through the use of these switch assemblies. One problem is that the trigger, which generally protrudes from the grinder housing, can be damaged if the grinder is dropped. Another problem is that the user's hand must grip the housing which is often large in diameter relative to the size of a user's hand. As such, a user can not reach around the housing to adequately grip the grinder while still activating the switch assembly, and in turn the grinder, by moving the trigger through the two paths of motion. Having an adequate grip is imperative for hand held power tools such as grinders in order to ensure that the user can accurately manipulate the grinder and the working element on the workpiece. Yet another drawback with existing switch assemblies is that they can only be operated with one hand location. That is to say existing switch assemblies do not enable a user to place their hand on the grinder at different points and in different orientations to impart different forces on the grinder in different directions depending on the task that is being performed with the grinder while enabling the user to activate the switch assembly from each hand placement.
A hand held power angle grinder is one form of power tool that may incorporate the present invention. It will be convenient to hereinafter describe the invention with particular reference to held power angle grinders, but it is to be understood that the invention has broader application. It will also be convenient to hereinafter describe the invention with particular reference to portable power tools, whereas the invention is applicable to power tools of a non-portable nature.
Accordingly, in a first aspect the present invention is directed towards providing a handle assembly for a hand held power tool, the assembly including:
first and second handle portions for gripping the power tool, the first handle portion extending substantially transverse to the second handle portion;
a trigger including an elongate portion associated with the first handle portion and a flange portion associated with the second handle portion; and
a switch for operating the power tool actuated by movement of either the elongate portion or the flange portion relative to the first or second handle portions respectively.
An advantage of the invention over existing gripping means and switch assemblies for holding and operating hand held power tools is that a user can grip and operate a device incorporating the invention more easily, more securely, with more control and with less discomfort. Another advantage is that a user need not grip the housing of such a device in order to operate a switch for turning the device on and off. Yet another advantage of a hand held power tool incorporating the present invention is that the user has a choice of handles with which to hold the device and move the trigger to actuate the switch and operate the tool. This enables a user to place their hand on the handle of a device incorporating the invention, such as a grinder, at different points and in different orientations to impart different forces on the grinder in different directions depending on the necessities of the task that being performed by the user.
Preferably, one end of the elongate portion is movably mounted to the first handle portion and an opposite end of the elongate portion is pivotally interconnected with the flange portion.
In another form, one end of the elongate portion is movably mounted to the first handle portion and an opposite end of the elongate portion is integrally formed with the flange portion.
In yet another form, the elongate portion and the flange portion are movable independently of each other.
In a preferred form, one end of the elongate portion is pivotally mounted to the first handle portion such that the elongate portion and the flange portion of the trigger pivot in an arc of motion to actuate the switch.
The handle assembly preferably includes a guard that is integral with one or more of the handle portions and is configured to form, together with the handle portions, a continuous loop around the trigger. This embodiment is advantageous in that it prevents the trigger from suffering damage if the power tool is dropped. It also reduces the likelihood of inadvertent operation of the trigger.
In one form the handle assembly includes an electric power lead for supplying electric current from a power source to the power tool. The power lead has two ends, one end is connectable to the power source and the other end is coupled to the guard. Having the power lead coupled to the guard is advantageous over existing arrangements where the power lead is coupled to the handle assembly nearer the switch thereby interfering with gripping the handle near the switch. Such interference from the power lead is avoided in this embodiment of the invention.
In another form, the switch has two parts, one part of the switch is integral with the elongate portion of the trigger and the other part of the switch is integral with the first handle portion such that movement of the trigger includes moving the elongate portion of the trigger towards the first handle portion for actuating the switch by engaging the two parts of the switch together.
Preferably, the trigger is attached to the first and second handle portions such that movement of the trigger to actuate the switch to operate the power tool involves sliding the trigger substantially longitudinally towards the second handle portion. This embodiment is advantageous in that it provides a means for avoiding inadvertent engagement of the switch parts and operation of the power tool.
In a preferred form, the invention further includes biasing means for biasing the trigger relative to the first and second handles to a default position in which the switch does not operate the power tool. This provides a resting state of the handle assembly in which power is not being supplied to the power tool such that the power tool is deactivated.
In yet another preferred form the invention may include a releasable trigger lock for releasably locking the trigger relative to the first and second handles in a position in which the switch operates the power tool. An advantage of this embodiment is that the user can activate the power tool by initially operating the trigger by hand and then, by locking the trigger, proceed to use the power tool for extended periods without having to retain the trigger in the operable position by hand.
In one form, the handle assembly of the present invention is pivotally mountable to the hand held power tool. In this form the handle assembly may pivot between various orientations relative to the hand held power tool. This form of the invention enables a user operating the power tool to adjust the handle assembly to a desired orientation that offers a secure and comfortable grip for the user with no discomfort or lack of control when the handle assembly is in any desired orientation. In various forms, the handle assembly may be pivotable to relative to an axis of the power tool through 360 degrees The assembly may be pivotable between 0 and 180 degrees or 0 and 90 degrees Preferably, the invention includes a means for retaining the handle assembly in the desired orientation and for releasing the handle assembly to pivot to another desired orientation. In one form, the pivotal mounting of the handle assembly to the power tool allows the handle assembly to rotate relative to the power tool.
Preferably the handle assembly of the present invention is for use in relation to a hand held power angle grinder. In one form, the assembly further includes a soft start control module for controlling power to the power tool. In another form, the assembly includes an overload protection device.
In another form, the handle assembly includes a trigger release mechanism which selectively enables movement of the trigger relative to the first or second handle portions. In one form, the trigger release mechanism includes a trigger release button which is mounted to the trigger and in a first position prevents relative movement of the trigger relative to the first or second handle portions and in a second position enables the trigger to move relative to the first or second handle portions. In another form, the trigger release button is normally in the first position and can be depressed by a user to the second position.
The present invention will now be described with reference to the figures of the accompanying drawings, which illustrate particular preferred embodiments of the present invention, wherein:
In
Although the handle assembly 10 of the present invention is shown in
The grinder 5 as shown by
As is shown in detail in
In addition, the trigger 30 further includes a safety means 65 for avoiding inadvertent engagement of the electrode 57 and the electrode receiver 58. The safety means 65 includes a guide for the movement of the trigger 30 such that for the trigger 30 to pivot in the arc of motion about the pivot point 60 between a position in which the electrode 57 and the electrode receiver 58 are in engagement and a position in which they are disengaged the trigger 30 must first be slid from an initial, default position as shown in
The guide also includes a second elongate slot (not shown) provided on any one or more of the first handle portion 20, the second handle portion 25, the flange portion 34 or the elongate portion 32 of the trigger 30. When the trigger 30 has slid a predetermined longitudinal distance in a direction away from the pivotal attachment 60 of the elongate portion 32 and towards the flange portion 34 of the trigger 30, the protrusion reaches the second elongate slot which may be provided on the same, or another one or more of the first handle portion 20, the second handle portion 25, the flange portion 34 or the elongate portion 32 of the trigger 30 onto which is provided the first elongate slot. The second elongate slot is oriented in a direction substantially transverse to the first handle portion 20. The protrusion in the second elongate slot slides longitudinally relative to the protrusion in the second elongate slot and in turn the trigger 30 slides longitudinally relative to the first handle portion 20 and the second handle portion 25 in a direction substantially transverse to the first handle portion 20.
Accordingly, the safety means 65 provides the switch and handle assembly 10 with a two stage action involving, firstly a slide action of the trigger 30 away from the grinder body 6 and towards the second handle portion 25, and then secondly, a pivoting action towards and into the first handle portion 20 where the electrode 57 and electrode receiver 58 are brought into engagement. This enables current to flow from the power supply through the power cord 50 and the switch 40 and on to activate the grinder 5. When the user releases the trigger 30 a biasing means (not shown) biases the trigger 30 in the reverse direction through the second and first elongate slots back to the initial, default position shown in
An advantage of the present invention is that the flange portion 34 and the elongate portion 32 of the trigger 30 are associated with the first handle portion 20 and the second handle portion 25 respectively. This enables a user to hold the grinder 5 by gripping either the first handle portion 20 or the second handle portion 25 and yet be able to operate the trigger 30 through the two stage action of the guide by firstly moving the trigger 30 away from the grinder body 6 and towards the second handle portion 25, and then secondly, pivoting the trigger towards and into the first handle portion 20 where the electrode 57 and electrode receiver 58 so as to actuate the switch 40 that operates the power tool 5. As will be appreciated this unique arrangement enables a user to apply force to the first handle portion 20 and the second handle portion 25 of the handle assembly 10, and in turn apply force to the grinder 5 and the working element 2, in different directions and in greater magnitudes, with greater ease of use and while still providing an accessible trigger 30 for activating the grinder 5, than has been possible with previous handle and switch assemblies.
As is shown in
The handle assembly 10 of the present invention is preferably pivotally mounted to the body 6 of the hand held power tool 5. This is enabled by providing a circular sleeve 70 on the handle assembly 10 that mounts to a short cylindrical portion 75 extending longitudinally from the body 6 of the grinder 5.
A detent 80 is provided adjacent to the circular sleeve 70 on the handle assembly 10. The detent 80 releasably engages the short cylindrical portion 75 extending longitudinally from the body 6 of the grinder 5 to retain the handle assembly 10 in a desired orientation and to release the handle assembly 10 to pivot to another desired orientation. However, other suitable means for releasably retaining the handle assembly 10 in a desired orientation may be used.
In another particularly preferred form, the handle assembly 10 also includes, as is particularly shown in
Another preferred feature of the invention that is not shown in the Figures is a releasable trigger locking means that enables a user to lock the trigger 30 in the position where the electrode 57 and electrode receiver 58 are brought into engagement to activate the grinder 5. The user can activate the grinder 5 by initially moving the trigger 30 by hand through the two stage action of the guide by firstly moving the trigger 30 away from the grinder body 6 and towards the second handle portion 25, and then secondly by pivoting the trigger towards and into the first handle portion 20 and then, by locking the trigger 30, proceed to use the grinder 5 for extended periods without having to retain the trigger 30 in position by hand. When the user wants to deactivate the grinder 5 the user releases the trigger locking means so that the trigger returns to its original position in which the electrode 57 and electrode receiver 58 are disengaged.
In
As can be seen generally in
In
As can be seen in
The above embodiments of the handle assembly 10, when applied to a power tool such as the grinder 5, results in the angle grinder satisfying the safety requirements of the trigger 30 to be manipulated in two substantially transverse directions to cause operation of the grinder 5 or other power tool having such safety requirements. When the user releases the trigger 30 the biasing means (not shown) biases the trigger 30 to the initial, default position shown in
An alternative form of the handle assembly 10, may include an arrangement of the trigger 30 such that the elongate portion 32 and the flange portion 34 are movable independently of each other. In one form, the elongate portion 32 may be depressable inwardly to the first handle portion 20 while the flange portion 34 remains stationary. Conversely, the flange portion 34 may be depressable inwardly to the second handle portion 20 while the elongate portion 32 remains stationary. In such forms of the invention, the switch 40 for operating the power tool 5 is still actuated by movement of either the elongate portion 32 or the flange portion 34 of the trigger 30 relative to the first handle portion 20 or second handle portion 25 respectively. There may also be more than one switch 40, one switch 40 being associated with the elongate portion 32 and one switch 40 associated with the flange portion 34. In yet another form, the handle assembly 10, or a power tool 5 incorporating the handle assembly 10, may include a secondary switch (not shown) for operating the power tool 5 when the switch 40 is actuated by movement of either the elongate portion 34 or the flange portion 34 of the trigger 30 relative to the first handle portion 20 or the second handle portion 25 respectively.
Referring to
As shown in
As in the embodiments of
In addition, as illustrated in
In
The trigger release mechanism 200 is advantageous in that it enhances the safety of the handle assembly 110 by providing a means for avoiding inadvertent depression of the trigger 130 and, therefore, inadvertent activation of the power tool. Accordingly, trigger release mechanism 200 provides the switch and handle assembly 110 with a two stage action involving, firstly a depression action of the trigger release button 210 and then secondly a pivoting action of the trigger 130 towards and into the first handle portion 120 where the switch 140 is actuated to activate the power tool.
Finally it is to be understood that various alterations, modifications and/or additions may be introduced to the parts previously described without departing from the spirit or ambit of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006902154 | Apr 2006 | AU | national |
This application is a continuation-in-part application of PCT Application No. PCT/AU2007/000537, filed Apr. 26, 2007, which claims priority to AU 2006902154, filed Apr. 26, 2006, both of which are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/AU2007/000537 | Apr 2007 | US |
| Child | 12258894 | US |
