Patent Description:
Fastener tools such as nail guns (a. nailers) are used to drive fasteners such as nails into a workpiece at a high speed.

Fastener tools may be vulnerable to back driving of the drive mechanism at the end of one striking cycle and before the start of the next striking cycle. Back driving can exert undue stress on the motor thereby causing a range of problems, from increasing latency time of the tool resulting in a diminished end-user experience, to short-term or long-term stress being exerted on the motor and ultimately damaging the fastener tool. Frequent or recurrent incidences of back driving can shorten the lifespan of the fastener tool and/or prolong the user handling time of the fastener tool, thereby negatively impacting the end user experience. Improved fastener tools are desired.

<CIT> represents the closest prior art and describes a fastener tool according to the preamble of claims <NUM> and <NUM>. <CIT> also presents related prior art in the field of fastener tools.

In the light of the foregoing background, it is an object of the present invention to provide a power tool which eliminates or at least alleviates the above technical problems.

The above object is met by the combination of features of the main claim; the subclaims disclose further advantageous embodiments of the invention.

One skilled in the art will derive from the following description other objects of the invention. Therefore, the foregoing statements of object are not exhaustive and serve merely to illustrate some of the many objects of the present invention.

Accordingly, the present invention, in one aspect can be seen in claim <NUM>.

Preferably, the rotating member and the receiving member are coplanar at least at the engaging portion.

In an exemplary embodiment, the biasing member biases the latch towards the receiving member.

Preferably, the latch locks with the receiving member when the when the rotating member rotates in a second direction such that the latch is locked in the first position.

In an exemplary embodiment, the latch defines a longitudinal direction and then the biasing member biases the latch from the longitudinal direction at a biasing angle of at least <NUM> degrees.

In a further exemplary embodiment, the latch defines a longitudinal direction and then the biasing member biases the latch from the longitudinal direction at a biasing angle of between <NUM> degrees and <NUM> degrees.

In an implementation, the biasing member is a coil spring.

In a further implementation, the rotating member comprises three said latches.

Preferably, the receiving member comprises repeating geometric features.

More preferably, each one of the repeating geometric features is asymmetric such that the rotating member is only rotatable in the first direction.

In an exemplary embodiment, the piston is accommodated in a high-pressure gas cylinder and suitable for a reciprocating motion within the high-pressure gas cylinder.

In another implementation, the piston is connected to a striking element suitable for striking a workpiece.

In a further exemplary embodiment, the drive mechanism comprises a blade fixed to the piston, and a gear coupled to the motor, the gear comprising a plurality of teeth adapted to engage with a plurality of lugs on the blade such that a rotation of the gear is transformed to a linear movement of the blade.

The present invention, in a further aspect can be seen in claim <NUM>.

In an example embodiment, the rotating member and the receiving member are coplanar at least at the engaging portion.

In a further embodiment, the biasing member biases the latch towards the receiving member.

In an example embodiment, the latch locks with the receiving member when the rotating member rotates in a second direction such that the latch is locked in the first position.

In an implementation, the latch defines a longitudinal direction and then the basing member biases the latch from the longitudinal direction at a biasing angle of between <NUM> degrees and <NUM> degrees.

In a further implementation, the biasing member is a coil spring.

In an example embodiment, the fastener tool includes three latches.

In another example embodiment, the receiving member includes repeating geometric features.

In yet another embodiment, each one of the repeating geometric features is asymmetric such that the rotating member is only rotatable in the first direction.

The embodiments of the present invention thus provide a fastener tool that is simple in construction, safe and reliable. The fastener tool includes a locking mechanism in the form of a locking module that is coupled with the drive mechanism that prevents back driving. The rotating member and the receiving member of the locking module are configured to permit the rotating member, and thus the drive mechanism, to rotate in a first direction. The rotating member is prevented from rotating in a second direction by the latch locking with the receiving member. The latch continuously pivoting between a first position and a second position facilitates the locking mechanism, wherein the biasing member biases the latch such that the latch may pivot towards or away from the receiving member. This locking mechanism advantageously allows for the latch to pivot inwards, or away from the receiving member, thus permitting rotation of the rotating member and drive mechanism during a drive cycle of the fastener tool, i.e. a nail gun, in a first direction and prevents rotation of the rotating member in a second direction, at the end of a drive cycle, as a result of the latch pivoting outwards, or towards the receiving member, such that the latch locks with the receiving member and cannot rotate.

This locking mechanism beneficially ensures the drive mechanism rotates only in one direction and prevents back driving at the end of one drive cycle, or strike cycle, and before the next strike cycle, due to reversed rotation of the drive mechanism that may occur as a result of a large reverse thrust in the pre-loading state of the fastener tool. This locking mechanism
advantageously prevents back driving and hence increased stress being exerted on the motor and potentially damaging it, and/or increased latency time for an improved end-user experience.

The locking mechanism provides an improved fastener tool with reduced latency time. The biasing member and the pivoting latch ensure the locking mechanism is reliable with a longer lifespan. Also, the locking mechanism is configured such that reduced torque is needed to unlock the rotating member and the receiving member when the strike cycle restarts. Further, the striking cycle can be automatically repeated continuously. This allows the motor in the fastener tool to operate without the need for interference, allowing for rotation in a single direction at a constant speed.

Some of the embodiments of the invention provide further advantages that enhance the performance of fastener tools. For example, by further dividing the interior of a single cylinder into a plurality of cylinder chambers, the timing of release of high-pressure gas, that is, the release of the piston, can be precisely controlled, which is achieved by controlling the size of the gas passage between the cylinder chambers. In addition, some embodiments of the present invention also include a plurality of bearings clamped on two opposite surfaces of the drive blade so as to support the drive blade in a stable manner, so that the blade can only move in a straight-line direction.

The foregoing and further features of the present invention will be apparent from the following description of preferred embodiments which are provided by way of example only in connection with the accompanying figures, of which:.

In the drawings, like numerals indicate like parts throughout the several embodiments described herein.

The following description is given by way of example only to illustrate preferred embodiments of the invention. In particular, the language and terminology used herein is for descriptive purposes only and is not intended to limit the scope or functionality of the invention. The invention may be employed in various combinations or embodiments utilizing various elements and means not explicitly described herein, but within the knowledge and skill of one skilled in the art.

Terms such as "horizontal", "vertical", "upwards", "downwards", "above", "below" and similar terms as used herein are for the purpose of describing the invention in its normal in-use orientation and are not intended to limit the invention to any particular orientation.

A problem that can occur during use of fastener tools, for example nail guns such as pneumatic nailers, is that during the pre-loading state, i.e. at the end of one strike cycle and before the start of the next strike cycle when the nail gun reaches a top dead center position, pressure from the gas spring can cause the drive mechanism to back drive through the gearing system. The back driving of the drive mechanism can exert undue stress on the motor and potentially damage the motor, a result that is both costly and inconvenient to a user of the nail gun. The back driving of the drive mechanism and motor also increases latency time during use of the nail gun whereby increased time is needed to account for the drive mechanism to rectify the reversal of the drive unit. Prolonged latency time decreases the efficiency of the nail gun and diminishes end user experience.

Some fastener tools in the prior art include frictional spindle locks in order to avoid the drive unit reversal. The spindle locks rely on frictional locking of the spindle by, for example, blocks to prevent the reversal in rotation. However, the frictional spindle lock structure has a number of shortcomings such as the frictional locking of the spindle slipping easily or wearing over time such that its effectiveness wanes over time, making the frictional spindle lock mechanism largely inefficient and not very useful due to its short lifespan and poor reliability. Another disadvantage of frictional spindle locks is that more torque is needed to unlock the rotating member when re-starting. It is an object of embodiments of the present invention to provide an improved locking mechanism for a fastener tool that achieves one-way rotation locking.

With reference to <FIG>, an exemplary embodiment provides a fastener tool <NUM> that includes a motor (not shown), a drive mechanism (not shown) coupled to the motor and adapted to drive a piston, and a locking module <NUM>. The locking module <NUM> comprises a rotating member <NUM>, coupled with the drive mechanism and adapted to rotate with a spindle <NUM> and defining a rotation axis <NUM>, and a receiving member <NUM> adapted to engage with the rotating member <NUM> at an engaging portion <NUM>.

Referring to <FIG> and <FIG>, the locking module <NUM> includes a rotating member <NUM> that is coupled with the drive mechanism and rotates with a spindle <NUM>. Preferably, the rotating member <NUM> surrounds the circumference of the spindle <NUM> such that the rotating member rotates with the spindle <NUM>, thereby defining a rotation axis <NUM> about which the rotating member <NUM> and spindle <NUM> rotate. The rotating member <NUM> engages with a receiving member <NUM> at an engaging portion <NUM>. The receiving member <NUM> surrounds or encircles the rotating member <NUM>. In an exemplary embodiment, the receiving member <NUM> is a fixed structure. The receiving member <NUM> includes repeating geometric features <NUM> on an inner surface of the receiving member <NUM> closest to an outer surface of the rotating member <NUM>. The repeating geometric features <NUM> act as cams that facilitate the locking mechanism of the locking module <NUM>. Each of the repeating geometric features <NUM> is asymmetric such that the rotating member <NUM> is only rotatable in the first direction. The repeating geometric features <NUM> are spaced evenly along the circumference of the receiving member <NUM>.

As can be seen from <FIG>, the rotating member <NUM> and the receiving member <NUM> are coplanar at least at the engaging portion <NUM>.

The engaging portion <NUM> is a portion wherein the surfaces of the rotating member <NUM> and the receiving member <NUM> come into contact. The engaging portion <NUM> is the outer surface of the rotating member <NUM>, i.e. the surface of the rotating member <NUM> that is farthest away from the spindle <NUM> and nearest to an inner surface of the receiving member <NUM>, i.e. the inner surface of the receiving member <NUM> nearest to the outer surface of the rotating member <NUM> with repeating geometric features <NUM>. The area of the engaging portion <NUM> may vary according to different phases, for example the engaging portion <NUM> may be greater, i.e. a greater area of surface contact or engagement between the rotating member <NUM> and the receiving member <NUM>, during an initial phase, reflecting the start of a drive cycle of the fastener tool <NUM> and initial rotation of the spindle <NUM>. The engaging portion <NUM> may then decrease as the rotational speed increases after the slower initial phase is passed and the area of surface contact or engagement between the rotating member <NUM> and the receiving member <NUM> decreases.

With reference to <FIG>, the rotating member <NUM> includes a latch <NUM> and a biasing member <NUM>. The latch <NUM> and the biasing member <NUM> move with the rotating member <NUM>. The biasing member <NUM> moveably supports the latch <NUM> in a biasing direction in a plane that is substantially perpendicular to the rotation axis <NUM>. The biasing member <NUM> biases the latch <NUM>, in a direction substantially perpendicular to the rotation axis <NUM>, towards the receiving member <NUM>. The biasing member <NUM> may be, for example, a coil spring.

The skilled person would appreciate that the term 'substantially perpendicular' as used herein may include, but is not limited to, an angle of <NUM> degrees to a given line, plane or surface. Accordingly, the term may include a range of <NUM> degrees to <NUM> degrees to a given line, plane, or surface.

As seen in <FIG>, the latch <NUM> is disposed along the outer periphery of the rotating member <NUM> such that the latch <NUM> completes the edges or profile of the circumference of the rotating member <NUM>. The movement of the latch <NUM> adjusts the perimeter and/or profile of the rotating member <NUM>. The latch <NUM> and the rotating member <NUM> may have different thicknesses.

With reference to <FIG> and <FIG>, the latch <NUM> continuously pivots between a first position <NUM> and a second position <NUM> about a pivot axis <NUM> when the rotating member <NUM> rotates in a first direction. In a preferred embodiment, the pivot axis <NUM> is parallel to the rotation axis <NUM>. As previously noted, the movement of the latch <NUM> between the first position <NUM> and the second position <NUM> adjusts the perimeter of the rotating member <NUM>. In the first position <NUM>, the latch <NUM> is at a released position, wherein the latch <NUM> defines a longitudinal direction <NUM> and the latch <NUM> is biased away from the longitudinal direction <NUM> by the biasing member <NUM> and the latch <NUM> moves towards, or is extended towards, the receiving member <NUM>. Conversely, in the second position <NUM> the latch <NUM> pivots from the first position <NUM> to the second, compressed, position <NUM>, wherein the engagement of the latch <NUM> with the receiving member <NUM> in the engaging portion <NUM> causes the latch <NUM> to pivot inwards about the pivot axis <NUM> towards the rotating member <NUM> and spindle <NUM>. Specifically, the latch <NUM> pivots inward from the first position <NUM> to the second position <NUM> when the latch <NUM> comes into contact with, and rides over, the repeating geometric features <NUM> of the receiving member <NUM>. The continuous pivoting of the latch <NUM> from the first position <NUM> and the second position <NUM> advantageously allows continuous and uninterrupted rotation of the rotating member <NUM>, and drive mechanism, in the first direction.

A biasing angle <NUM> of the locking module <NUM> varies when the latch <NUM> is pivoting. With reference to <FIG>, the latch <NUM> defines a longitudinal direction <NUM> and the biasing member <NUM> biases the latch <NUM> from the longitudinal direction <NUM> at a biasing angle <NUM> of at least <NUM> degrees (A). In an exemplary embodiment, the rotating member <NUM> includes at least one latch <NUM>. The rotating member <NUM> may include a plurality of said latches <NUM>. In a preferred embodiment, the rotating member <NUM> comprises three said latches <NUM>. The malposition biasing angle <NUM> of the latch <NUM> advantageously reduces the chance of slippage between the latch <NUM> and the receiving member <NUM>.

The latch <NUM> is coupled to the rotating member <NUM> such that the latch <NUM> can pivot in two different planes, facilitated by the biasing member <NUM>. For example, as shown in <FIG>, the latch <NUM> has a pivoting direction in a radial plane that is perpendicular to the rotation axis <NUM>. The latch <NUM> may also have a pivoting direction in a different second plane to the radial plane, i.e. angled away from the radial plane, however the pivoting action of the latch <NUM> in the second plane may be less than the pivoting action in the radial plane. For example, the second plane may be angled within a range of <NUM>-<NUM> degrees of the radial plane. In a further example, the second plane may be angled <NUM>-<NUM> degrees of the radial plane. In an alternative embodiment, the second plane may be perpendicular to the radial plane.

With reference to <FIG>, the locking module <NUM> of the present invention prevents back driving by allowing only one way rotation of the rotating member <NUM> in the first direction. When the rotating member <NUM> rotates in the second direction, the latch <NUM> in the first position <NUM> locks with the receiving member <NUM>, specifically the repeating geometric features <NUM>, or teeth <NUM> of the receiving member <NUM>, such that the latch <NUM> is locked in the first position <NUM> and cannot rotate, thereby preventing the rotating member <NUM> from rotating in the second direction and actively preventing back driving.

In another exemplary embodiment as shown in <FIG>, a locking module <NUM> similar to that in <FIG> may be positioned near the gearbox of the fastener tool <NUM>. when the fastener tool <NUM> reaches top dead center at the end of one drive cycle and rests before the next drive cycle begins, the pressure from, for example in the case of a pneumatic nailer, a gas spring can cause the drive mechanism to back drive through a gearing system. When back driving occurs, the drive mechanism and spindle <NUM> rotate in the second direction, i.e. opposite to the direction of rotation of the motor. This back driving phenomenon can harm the motor by exerting undue stress and/or also increase the latency time for use of the fastener tool <NUM> such that end user experience is diminished.

The fastener tool <NUM> with the locking mechanism as described provides an improved fastener tool with a locking module <NUM> that locks the spindle without friction. This superior locking mechanism additionally only requires a low torque for restarting rotation. The fastener tool <NUM> with the locking mechanism is advantageously more reliable with low to no incidence of accidental slippage.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only exemplary embodiments have been shown and described and do not limit the scope of the invention in any manner. It can be appreciated that any of the features described herein may be used with any embodiment. The illustrative embodiments are not exclusive of each other or of other embodiments not recited herein. Accordingly, the invention also provides embodiments that comprise combinations of one or more of the illustrative embodiments described above. Modifications and variations of the invention as herein set forth can be made without departing from the spirit and scope thereof, and, therefore, only such limitations should be imposed as are indicated by the appended claims.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

For example, although the specific embodiment shown in <FIG> shows three latches <NUM> configured on the rotating member <NUM>, those skilled in the art should realize that other variations of the number of latches <NUM> are possible. For example, there could be more or less than three latches <NUM> on the rotating member <NUM>, and even one latch <NUM> is possible in some applications.

In addition, although the specific embodiment in <FIG> shows the locking module <NUM> positioned near the gearbox of the fastener tool <NUM>, those skilled in the art will appreciate that the locking module <NUM> may be positioned elsewhere in the fastener tool <NUM>, such as near the output side towards the bevel gear set, for example.

In a variation of the embodiment shown in <FIG>, the end of the latch <NUM> nearest the pivot <NUM> may optionally be a cam to facilitate the locking mechanism.

In a further variation of the embodiment shown in <FIG>, the receiving member <NUM> may be a clutch that can be selectively engaged or disengaged.

In a further variation of the embodiment shown in <FIG>, the spacing between the geometric features <NUM> may be varied or uneven.

Alternatively, the rotating member <NUM> and the latch <NUM> may be completely or partially coplanar.

In a further variation of the embodiment shown in <FIG>, the biasing angle <NUM> may be between <NUM> degrees and <NUM> degrees. In yet another embodiment, the biasing angle may be between <NUM> degrees and <NUM> degrees. In a preferred embodiment, the biasing angle is <NUM> degrees or <NUM> degrees.

In a further variation of the embodiment shown in <FIG>, when the rotating member <NUM> includes a plurality of said latches <NUM>, the biasing angle <NUM> of all said latches <NUM> may be the same. Alternatively, each said latch <NUM> may have different biasing angles <NUM>.

In a further exemplary embodiment, the piston is connected to a striking element suitable for striking a workpiece.

In one implementation, the drive mechanism comprises a blade fixed to the piston, and a gear coupled to the motor, the gear comprising a plurality of teeth adapted to engage with a plurality of lugs on the blade such that a rotation of the gear is transformed to a linear movement of the blade.

Claim 1:
A fastener tool (<NUM>) comprising:
a motor;
a drive mechanism connected to the motor and adapted to drive a piston; and
wherein the drive mechanism comprises a blade fixed to the piston, a gear is coupled to the motor, the gear comprising a plurality of teeth adapted to engage with a plurality of lugs on the blade such that a rotation of the gear is transformed to a linear movement of the blade characterised by
a locking module (<NUM>) comprising a rotating member (<NUM>) coupled with the drive mechanism and adapted to rotate with a spindle (<NUM>) and defining a rotation axis (<NUM>), and a receiving member (<NUM>) adapted to engage with the rotating member at an engaging portion (<NUM>);
the rotating member comprising a latch (<NUM>) and a biasing member (<NUM>), wherein the biasing member moveably supports the latch in a direction substantially perpendicular to the rotation axis.