WO2016115705A1

WO2016115705A1 - Power tools containing locking mechanisms and method of engaging such locking mechanisms

Info

Publication number: WO2016115705A1
Application number: PCT/CN2015/071302
Authority: WO
Inventors: Xingxing CHEN; Jingfeng Zhou; Liguo Ma; Jinlin Zhou
Original assignee: Techtronic Industries Company Limited
Priority date: 2015-01-22
Filing date: 2015-01-22
Publication date: 2016-07-28
Also published as: EP3247538B1; AU2015378403A1; EP3247538A1; AU2015378403B2; EP3247538A4; CN107206580A

Abstract

A power tool for driving a fastener includes a cylinder (50) and a drive piston (54) within the cylinder (50), the drive piston (54) being acted on by a driving force resulting from a pressure difference, the drive piston (54) being moveable between an initial position and a driving position. The power tool further includes a drive blade (42) coupled to the drive piston (54) and operable to drive a fastener and a locking mechanism (300) that operates through engagement between at least two catches (306, 308) and at least two locking members (304, 305). By adopting such a double-action locking mechanism (300), the power tool is significantly safer than the common general power tools for driving a fastener.

Description

POWER TOOLS CONTAINING LOCKING MECHANISMS AND METHOD OF ENGAGING SUCH LOCKING MECHANISMS

FIELD OF THE INVENTION

The present invention relates to power tools， and more specifically to powered fastener drivers.

BACKGROUND OF THE INVENTION

There are various fastener drivers known in the art for driving fasteners (e.g.， nails， tacks， staples， etc. ) into a workpiece. These fastener drivers operate utilizing various means known in the art (e.g.， compressed air generated by an air compressor， electrical energy， flywheel mechanisms) ， but often these designs uses simple locking mechanisms for preventing accidental operations of thc trigger and thus unwanted and often dangerous fastener propulsion. Such simple locking mechanisms often are not reliable over time， as they are easy to wear out and result in malfunctioning of the locking mechanism.

SUMMARY OF THE INVENTION

The invention provides， in one aspect， a power tool for driving a fastener including a cylinder； a drive piston within the cylinder， the drive piston being acted on by a driving force resulting from a pressure difference， the drive piston being moveable between an initial position and a driving position； a drive blade coupled to the drive piston and operable to drive a fastener； wherein the power tool includes a locking mechanism that operates through engagement between at least two catches and at least two locking members.

Preferably， the at least two catches are at least two notches which are integrally formed on the drive blade.

In one implementation， one of the at least two notches including a ramp.

In a further aspect of this implementation， the at least two notches are formed on a side of the drive blade.

Preferably， the at least two locking members are at least two pins which are mounted with a holder which is separated from the drive blade.

In one implementation， the pins have a circular or an ellipsoidal cross section.

In a further aspect of this implementation， the engagement between the at least two pins and the at least two notches are dependent on the holder’s location.

In another implementation， the holder is biased by a resiliently deformable member， which is mounted between a tab portion of the holder and a structural portion of the power tool.

In yet another implementation， the holder is pivotable between a locking position and an unlocking position.

In a further implementation， the holder pivots in a first direction that the at least two pins move away from the at least two notches when the holder’s tab is pressed by a trip member.

In yet a further implementation， the holder pivots in a second direction that the at least two pins move closer to the at least two notches when the holder’s tab is separated from the trip member.

In a further aspect of this implementation， the at least two pins disengages from the at least two notches when the holder pivots in the first direction.

In another aspect of this implementation， the at least two pins attempt to engage the at least two notches when the holder pivots in the second direction.

In yet another aspect of this implementation， a first one of the at least two pins will engage with the at least two notches and the second one of the at least two pins will only engage with one of the at least two notches.

The invention provides， in another aspect， a method for engagement of a locking mechanism which including urging a drive blade locked by a locking mechanism to a driving position so as to drive a fastener； urging a holder to a first direction and moving at least two locking members away from at least two catches for disengaging the locking mechanism so that the drive blade can be operated for driving a fastener.

In one implementation， oone of the at least two notches including a ramp.

Preferably， the pins have a circular or an ellipsoidal cross section.

The invention provides， in yet another aspect， A method for engagement of a locking mechanism which including urging a drive blade to an initial position so as to engage a locking mechanism； urging a holder to a second direction； moving the at least two locking members closet to the at least two catches so that during the drive blade’s return travel， at least one of the locking members is in contact with one of the at least two catches on the drive blade and positioning the at least two locking members with a respective catch for engaging the locking mechanism.

In one implementation， one of the at least two notches including a ramp.

In another implementation， the pins have a circular or an ellipsoidat cross section.

In yet another implementation， the method including altering the holder’s position so as to control engagement between the pins and the notches.

In a further implementation， the method for engagement of the locking mechanism which including engaging at least two locking members with a respective catch so as to lock the drive blade to prevent accidental movement of the drive blade； engaging a first locking member with a first notch then shifting the first locking member out of the first notch from the ramp； engaging the first locking member with a second notch whilst engaging a second locking member with the first notch so as complete the locking mechanism engagement.

Other aspects of the invention will become apparent by consideration of the detailed dcscription and accompanying drawings.

The current invention including a locking mechanism that can securely restrict the movement of the drive blade for preventing unintended driving of fasteners. By using a multitude of engagement points for the locking mechanism， the longevity of this locking mechanism is therefore greatly improved from the convention locking mechanism where generally only one engagement point is used for locking. As there are at least two locking members and at least two catches being formed and configured to function as the locking mechanism， the force being exerted onto the locking members are practically halved which would result in more than doubling of each locking member’s durability. Both pins are now working well under their critical yield strength so the chance of these pins failing has been greatly reduced. Also， the double action pin/notch mechanism makes an additional safety measure， that in case of one of the pins is broken there is still another pin which can at least provide temporary locking function to the blade in the operation.

Before any embodiments of the invention are explained in detail， it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a powered fastener driver in accordance with an embodiment of the invention.

FIG. 2 is a partial cutaway view of the powered fastener driver of FIG. 1 with a cylinder shown in phantom.

FIG. 3 is a cross-sectional view of a locking mechanism of the powered fastener driver of FIG. 1.

FIG. 4 is a perspective view a holder of the locking mechanism of FIG. 3.

FIG. 5 is a cross-sectional view of the holder in a locking position of the locking mechanism of FIG. 3.

FIG. 6 is a top view of the holder of FIG. 4 moving in a first direction towards an unlocking position.

FIG. 7 is a top view of a striking pin of FIG. 4 in a driving position.

FIG. 8 is a top view of the striking pin of FIG. 4 returning to an initial position.

FIG. 9 is a top view of the holder of FIG. 4 moving in a second direction towards a locking position.

FIG. 10 is a top view of the holder of FIG. 4 moving towards a locking position.

FIG. 11 is a top view of the striking pin of FIG. 4 in an initial position being locked by the locking mechanism.

DETAILED DESCRIPTION

Fig. 1 illustrates a vacuum powered fastener driver 10 operable to drive fasteners such as nails， tacks， staples and etc. held within a magazine 14 into a work piece. The fastener driver 10 includes an outer housing 18 with a handle portion 22， and a user-actuated trigger 26 mounted on the handle portion 22. The fastener driver 10 does not require an external source of air pressure， but rather includes an on-board vacuum system 30 as shown in Fig. 2. The vacuum system 30 is powered by a power source such as a battery pack 34， which is coupled to a battery attachment portion 38 of the outer housing 18. In alternative embodiments， alternative power sources such as an electrical cord may be used to provide power to the vacuum system 30.

With reference to Fig. 1， the fastener driver includes a drive blade 42 actuated by the vacuum system 30 to drive the fasteners into a work piece. The vacuum system 30 includes a variable-volume vacuum chamber 46 defined within a cylinder 50， between a drive piston 54 and an elevator or a reciprocating piston 58. the drive blade 42 is coupled to the drive piston 54， and the vacuum chamber 46 creates a driving force as a result of differential pressure acting on the drive piston 54. The reciprocating piston 58 is driven in a reciprocating manner by a drive assembly that is not shown. In the illustrated embodiment of the fastener driver 10， the drive asscmbly includes a motor 74， a transrnission that receives torque from the motor 74， a pinion 66 and connected to the drive piston 54 for reciprocation therewith.

With reference to Fig. 2， a vacuum is developed within the vacuum chamber 46 by moving the reciprocating piston 58 away fiom the drive piston 54， while the position of the drive piston 54 is held or maintained. A bumper 76 is positioned in a bottom portion of the cylinder 50 and absorbs impact forces from the reciprocating piston 58 and drive piston 54. The bumper 76 includes projections 77 that are received in corresponding recesses (not shown) formed in the reciprocating piston 58.

In order to ensure the operational safety of the fastener driver 10， a locking mechanism is designed and implemented. With reference to Fig. 3， the locking mechanism 300 includes a holder 302 which further includes a plurality of components that are designed to work in tandem with the drive blade’s shaft portion 301 so as to provide a locking function for preventing accidental actuation of the fastener driver 10. The holder 302 pivots about an axle 310， which is configured in a fixed portion near the front end of the fastener driver 10. The holder 302 is further connected with the same fixed portion by a resiliently deformable member 314 that is disposed between the fixed portion and a finger 312 on the holder 302. In this embodiment， a spring 314 is used for providing a biasing force so as to urge the holder in a first direction. The holder 302 may include a plurality of locking members and in this embodiment， the holder 302 includes two locking

members

304， 305 in the form of a pin， which are designed to interact with catches formed on the drive blade’s shaft portion 301. The holder 302 also has a tab portion 318 for being engaged with a trip portion 316 from the reciprocating piston 58 for urging the holder 302 into a second direction.

The locking mechanism 300 relies on the automatic engagement between the

pins

304， 305 on the holder 302 and the

catches

306， 308 which are integrally formed on the drive blade 42. The

pins

304， 305 may have circular cross sections or in some instances ellipsoidal cross sections. The

pins

304， 305 are made of a high strength material or preferably an alloy that has high resistance to impact loading and fatigue. Also， the material used should also have high ductility so as to allow the user some leeway for noticing the conditions of the

pins

304， 305 from the positioning of the drive blade 42 in the initial position. Brittle materials should be avoided as snapping of the

pins

304， 305 would allow fasteners to be driven accidentally and thus becoming a hazard to the user.

The

pins

304， 305 are designed to engage with the catches that are integrally formed on the drive blade 42. The catches in this embodiment are two notches formed serially along the drive blade’s longitudinal direction. The two notches is consisting of a first notch 306 and a second notch 308. The first notch 306 is different to the second notch 308 in a way that the first notch includes a slanted edge， which is a ramp 307 in this embodiment as shown in Fig. 3. The second notch 308 only has a symmetrically formed profile. The two notches are spaced apart from each other and the ramp 307 forms a smooth transition between the first notch 306 and the second notch 308.

Now turning to the operation of the device described above， Fig. 4 shows the locking mechanism 300 in a locking position whilst the drive blade 42 is in an initial position. The holder 302 is urged by a spring (not shown) and the result is that the two

pins

304， 305 are fully engaged with the first and

second notches

306， 308. In the initial position， the longitudinal movement of the drive blade 42 along its longitudinal axis is fully restricted by the locking mechanism 300 so that maximum safety is ensured. With reference to Fig. 5， the cross-sectional view of the locking mechanism 300 reveals that each

304， 305 is engaged with a respective notch and the

pins

304， 305 are urged by the spring (not shown) through the holder 302 toward a locking position for restricting the movement of the drive blade 42.

In order to utilize the locking mechanism as shown in Figs. 6-11 for driving a fastener into a work piece， a user actuates the trigger (not shown) of the fastener driver for powering of the motor. Actuation of the trigger will cause the reciprocating piston to move toward the holder and allowing the trip portion on the reciprocating piston to engage the tab portion 318 on the holder 302. The holder 302 will be urged to a first direction， which in this embodiment is the anti-clockwise direction. The movement of the holder 302 will also cause the at least two locking members moving away from the at least two catches and therefore derestricting the movement of the drive blade 42. Fig. 7 shows a drive blade 42 to be in its driving position for driving a fastener. As the figure shown， the at least two catches are well beyond the at least two locking members on the holder 302.

Once the drive blade 42 has driven a fastener into a work piece， in this embodiment the reciprocating piston will move in the direction of the drive blade’s initial position and therefore causing the trip portion on the reciprocating piston to disengage from the tab portion 318 of the holder 302. Such disengagement will also rid of any biasing force acted on the tab portion 318 of the holder 302. Accordingly， the holder 302 in this embodiment will be urged in a second direction， which is the clockwise direction so as to move the at least two locking members in the direction of the drive blade 42. The first locking member 305 will be caught by the first catch 306 as shown in Fig. 8 during the return of the drive blade 42 toward its initial position. However， as shown in Figs. 9-10， the locking member being caught by the first catch 306 will then be slid out of the first catch 306 along a ramp 307 that is formed between the first catch 306 and the second catch 308. The locking member will then slide towards to the second catch 308 as the drive blade continues returning to its initial position.

Once the drive blade 42 has completed returning to its initial position as shown in Fig. 11， both of the locking members 304 engage with a respective first and

second catch

306， 308 and completing the locking function of the locking mechanism 300. As Fig. 11 shown， the two locking

members

304， 305 are both being urged toward the longitudinal edge of the

catches

306， 308 to ensure that the drive blade 42 would be securely restricted for preventing any accidental movement.

In another embodiment that is not shown in the figures， another fastener driver may have a locking mechanism that includes more than two locking members and more than two catches. The locking members and the catches will be similarly formed as the embodiment in Figs. 3-11 as in the locking members will also be pins that have either a circular cross-section profile or an ellipsoidal cross-section profile. The catches would also be integrally formed on the drive blade except that there will be at least two ramps being formed should there be three catches.

Although the invention has been described in detail with reference to certain preferred embodiments， variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described.

Claims

A power tool for driving a fastener including：

a cylinder；

a drive piston within the cylinder， the drive piston acted on by a driving force resulting from a pressure difference， the drive piston moveable between an initial position anda driving position；

a drive blade coupled to the drive piston and operable to drive a fastener；

wherein the power tool cornprises a locking mechanism that operates through engagement between at least two catches and at least two locking members.
The power tool of claim 1， wherein the at least two catches are at least two notches which are integrally formed on the drive blade.
The power tool of claim 2， wherein one of the at least two notches comprises a ramp.
The power tool of claim 3， wherein the at least two notches are formed on a side of the drive blade.
The power tool of claim 1， wherein the at least two locking members are at least two pins which are mounted with a holder which is separated from the drive blade.
The power tool of claim 5， wherein the pins have a circular or an ellipsoidal cross section.
The power tool of claims 5 or 6， wherein the engagement between the at least two pins and the at least two notches are dependent on the holder’s location.
The power tool of claim 5， wherein the holder is biased by a resiliently deformable member， which is mounted between a tab portion of the holder and a structural portion of the power tool.
The power tool of claim 5， wherein the holder is pivotable between a locking position and an unlocking position.
The power tool of claim 5， wherein the holder pivots in a first direction that the at least two pins move away from the at least two notches when the holder’s tab is pressed by a trip member.
The power tool of claim 5， wherein the holder pivots in a second direction that the at least two pins move closer to the at least two notches when the holder’s tab is separated from the trip member.
The power tool of claim 11， wherein the at least two pins disengages from the at least two notches when the holder pivots in the first direction.
The power tool of claim 11， wherein the at least two pins attempt to engage the at least two notches when the holder pivots in the second direction.
The power tool of claim 13， wherein a first one of the at least two pins will engage with the at least two notches and the second one of the at least two pins will only engage with one of the atleast two notches.
A method for engagement of a locking mechanism， including：

urging a drive blade locked by a locking mechanism to a driving position so as to drive a fastener；

urging a holder to a first direction and

moving at least two locking members away from at least two catches for disengaging the locking nechanisrn so that the drive blade can be operated for driving a fastener.
The method for engagement of the locking mechanism of claim 15， wherein the at least two locking members are at least two pins which are mounted with a holder which is separated from the drive blade.
The method for engagement of the locking mechanism of claim 15， wherein the at least two catches are at least two notches which are integrally formed on the drive blade.
The method for engagement of the locking mechanism of claim 17， wherein one of the at least two notches includes a ramp.
The method for engagement of the locking mechanism of claim 15， wherein the pins have a circular or an ellipsoidal cross section.
A method for engagement of a locking mechanism， including：

urging a drive blade to an initial position so as to engage a locking mechanism；

urging a holder to a second direction；

moving the at least two locking members closer to the at least two catches so that during the drive blade’s return travel， at least one of the locking members is in contact with one of the at least two catches on the drive blade and

positioning the at least two locking members with a respective catch for engaging the locking mechanism.
The method for engagement of the locking mechanism of claim 19， wherein the at least two locking members are at least two pins which are mounted with a holder which is separated from the drive blade.
The method for engagement of the locking mechanism of claim 19， wherein the at least two catches are at least two notches which are integrally formed on the drive blade.
The method for engagement of the locking mechanism of claim 22， wherein one of the at least two notches includes a ramp.
The method for engagement of the locking mechanism of claim 20， wherein the pins have a circular or an ellipsoidal cross section.
The method for engagement of the locking mechanism of claims 15 or 20， wherein the method includes altering the holder’s position so as to control engagement between the pins and the notches.
The method for engagement ofthe locking mechanism ofclaim 23， further comprises：

engaging at least two locking members with a respective catch so as to lock the drive blade to prevent accidental movement of the drive blade；

engaging a first locking member with a first notch then shifting the first locking member out of the first notch from the ramp； and

engaging the first locking member with a second notch whilst engaging a second locking member with the first notch so as complete the locking mechanism engagement.