GB2363520A

GB2363520A - Power tool actuator

Info

Publication number: GB2363520A
Application number: GB0014532A
Authority: GB
Inventors: Colin Thomas Cochrane
Original assignee: Black and Decker Inc
Current assignee: Black and Decker Inc
Priority date: 2000-06-15
Filing date: 2000-06-15
Publication date: 2001-12-19
Anticipated expiration: 2020-06-15
Also published as: GB0014532D0; GB2363520B

Abstract

An actuator 2 for a power tool has a pivot point 32 about which the actuator may pivot during use thereof. A detent 14 mounted within the actuator 2 is itself pivotable and must be actuated before the actuator can operate the power tool. Situated between the detent 14 and the actuator 2 is a compression spring 50 which serves to return the detent to its rest position once the actuator 2 has been operated.

Description

2363520 POWER TOOL ACTUATOR

The present invention relates to a power tool actuator switch as set out in the preamble of Claim 1.

Such a switch is used, for example, to actuate an electric relay which enables actuation of an electric motor of, for example, an angle grinder, or the like power tool.

For some tools it is important that the actuator switch be disabled until a safety 10 catch or safety mechanism has itself been operated first. The reason for this is that some tools are inherently dangerous because they have either a rotating or reciprocating output spindle or shaft which may itself carry a dangerous implement such as a grinding disc, saw blade or the like. Because the accessory such as the grinding disc or saw blade often wears out and needs replacing a user must be offered 15 every safety feature for safely changing the accessory without actuating the tool by accident. It is not uncommon for users to either forget to or refrain from unplugging the power tool from the mains electricity supply before changing the accessory. In such an event it is important to utilise a safety lock-off device so that the tool may not inadvertently be operated during change of the accessory thereby avoiding the 20 possibility of physical harm being done to the user.

It is therefore an object of the present invention to provide a power tool actuator switch whose rest position is reliably lock-off. This means that a detent mechanism must be actuated prior to the actuator switch allowing operation of the 25 power tool.

According to the present invention, therefore, there is provided a power tool actuator switch according to the preamble of Claim 1 characterised in that the biassing is achieved by a compression spring mounted between the actuator switch and the

30 detent. Provision of a compression spring provides a more compact arrangement of P-UK-CS1093 actuator switch than has been known hitherto and also provides for a greater force needing to be applied to the detent before the switch itself can be activated.

Preferably the switch includes at least one depending arm for defining the 5 pivot point. This provides a convenient way in which the pivot point may be included in the main body of the switch itself.

Preferably at least one depending ann consists of a plurality of arms. This provides a more stable pivoting arrangement than the use of a single pivot point.

According to a preferred embodiment the spring is a coiled compression spring.

Advantageously, the detent includes a flange for providing an operating 15 surface against which operating surface the spring acts.

Preferably, the pivot point is defined by at least one spigot on the actuator switch.

20 Additionally or alternatively each of the arrns of the plurality of arms may be associated with a respective spigot.

The present invention will now be described, by way of example only, and with reference to the following drawings of which:

Figure I shows a planar view of an actuator switch according to the present invention from above; Figure 2 shows a side view partially in section of the switch of figure 1; Figure 3 shows a side view of the switch of figure 1; P-UK-CS 1093 Figure 4 shows in perspective the switch of figure 1; Figure 5 shows an end view of the switch of figure 1 from above; 5 Figure 6 shows a plan view of the switch of figure 1 from below; Figure 7 shows a perspective view of a pivotable detent in accordance with the present invention; 10 Figure 8 shows an end view of the detent of figure 7; Figure 9 shows an end view of the detent of figure 7 from the opposite side of that shown in figure 8; 15 Figure 10 shows a side view of the detent of figure 7; Figure 11 shows an end view of a power tool (with its outer clamshell partially removed) incorporating an actuator switch in accordance with the present invention; 20 Figure 12 shows a part sectional view taken along the axis A-A of figure 11; Figure 13 shows a view similar to that of figure 11, but with the pivotal detent actuated to allow release of the actuator switch; 25 Figure 14 shows a view similar to that of figure 12 but, again, with the pivotal detent actuated to allow release of the actuator switch; Figure 15 shows a view similar to figures 11 and 13 with the actuator switch 30 having been activated, and; P-UK.CS1093 Figure 16 shows a view similar to that of figures 14 and 12 but with the actuator switch, again, having been activated.

Referring now firstly to figures 1-6, it can be seen that an actuator switch in 5 accordance with the present invention comprises a moulding of plastics material shown generally as 2. The moulding is forined so as to provide a scalloped portion 4 defining a surface operable by a user. It will be seen that the scalloped portion 4 is formed so as to have an outer generally convex shape to surface seen most readily from figure 5 shown as reference numeral 6 and an inner generally concave surface 8 10 seen most readily in figure 4. The inner concave surface 8 of the moulding 2 is forined so as to have a plurality of supporting ribs 10 to help ensure that the overall structure of the moulding 2 is rigid. Of course, depending upon the nature of the material from which the moulding 2 is formed, then the ribs 10 may not be necessary for rigidity. However, inclusion of such ribs 10 in moulding technology is not 15 difficult and aids in rigidity of the finished structure.

It can be seen that the scalloped portion 4 has a hole 12 centrally formed therein. The purpose of the hole 12 will be described further below but is to allow a pivoting detent 14 shown in figures 7-10 to pass therethrough.

Referring now also to figures 7-10, it can be seen that the pivoting detent 14 comprises a pivot point 16 fonned as a generally cylindrical spigot and preferably as an integral part of the detent 14. A manually operable actuation portion of the detent, in this example serrated edge 18, is coupled to the pivot point 16.

It can be seen from the figures that the pivoting detent 14 is formed in a generally U-shaped cross section and the method by which the detent 14 operates will be explained further below.

30 When viewing the detent 14 in section as a U-shaped member, it can be seen that at the opposite end from the "U" ftom the pivot point 16 is an oversize lateral P-UK-CS1093 projection 20. The projection 20 comprises a pair of lugs which project either side and beyond the width 22 of the detent 14.

It will also be seen from figures 7-10 that the detent 14 includes a projecting 5 flange, in this example a pair of arms 24 which may either be formed integrally with the remainder of the detent 14 or as a separate unit coupled thereto.

Referring now additionally to figures 11-16, the method by which the moulding 2 and pivoting detent 14 co-operate and operate within a power tool will be 10 described.

Figures 11 and 12 show the situation where the moulding 2 and pivoting detent 14 are in their rest position such the power tool cannot operate.

15 It can be seen from figures 1-6 and 11 and 12 that the moulding 2 has formed therein a recess 26 for accepting the pivot point 16 of the pivoting detent 14. The recess 26 allows pivoting of the pivot point 16 therewithin.

The detent 14 is oriented with respect to the moulding 2 such that the serrated 20 edge 18 projects out through the hole 12 of the moulding 2 so as to be accessible by a user of a power tool. In this example the power tool chosen is an angle grinder 28, although the invention is equally efficacious with any other power tool such as a drill, driver or sander or the like.

25 The moulding 2 itself is pivotally mounted within the body of the power tool 28 by virtue of at least on depending arm, in this example a pair of depending arms 30 each being formed with a respective spigot 32. The spigots 32 each sit within a corresponding recess 34 formed within the body of the angle grinder 28. In this example, the angle grinder 28 is formed by bringing together two half clam shells (one 30 of which 36 is shown in figure 11) and the recess 34 is formed in each of the clam shell halves 36. In this manner, therefore, the moulding 2 is able to pivot about the P-UK-CS 1093 spigots 32 in addition to the detent 14 being able to pivot about the pivot point 16 when arranged to be seated within the moulding 2.

Referring particularly to figure 12 it can be seen that the moulding 2 includes a 5 further plurality of arms, in this example projections 38, the purpose of which will be described further below. The projections 38 each have formed therein a respective hole 40 the purpose of which, again, will be described below.

It can be seen that the moulding 2 of figure 12 is prevented from being 10 actuated and thereby pivoting about pivot point 32 by virtue of the detent 14 preventing movement thereof. Specifically, the pair of lugs 20 (in the inoperable position shown in figures I I and 12) abut against a stop member 42 formed within the body of the angle grinder 28. The user who tries to actuate the moulding 2 finds that the abutment between the pair of lugs 20 of detent 14 and the stop member 42 prevent 15 pivoting of the moulding 2. In this manner, therefore, the ribs 10 of the moulding 2 are unable to actuate the electrical switch 44 within the angle grinder 28. Therefore, the arrangement shown in figure 12 acts as a lock-off switch.

In order to actuate the electrical switch 44, referring now to figures 13 and 14 20 it can be seen how the lock-off switch can be de-activated to allow the user to actuate the moulding 2 and hence the electrical switch 44.

Comparing figures 12 and 14 it can be seen that in figure 12 the user has applied pressure to the serrated edge IS of the detent 14 in a direction shown by the 25 arrow in figure 14 and caused it to pivot about pivot point 16. Because the detent 14 is able to pivot about point 16, then the pair of lugs 20 have (in figure 14) moved past the stop member 42 thereby permitting pivoting of the moulding 2 about the spigots 32 on arms 30. In this manner, therefore, the ribs 10 are able to actuate the electrical switch 44.

P-UK-CS 1093 it is important to note that unless and until the pivoting detent 14 has been actuated as shown in figure 14 then no pivoting of the moulding 2 is able to take place. This is due to the abutment between the pair of lugs 20 and the stop member 42 occurring should a user try to actuate the moulding 2 without having first pivoted 5 the detent 14 out of the way as shown in figure 14.

RefeMng now, finally to figures 15 and 16 it will be seen how, following actuation of the detent 14, actuation of the moulding 2 is possible.

10 As has been mentioned here above, because the pair of lugs 20 and the stop member 42 are no longer in abutment due to the prior pivoting of the detent 14 about pivot point 16, then the user may apply force to the moulding 2 in the direction of the arrow shown in figure 16 which causes the actuation of the electrical switch 44 by the moulding 2.

Furthermore, it can be seen from figures 14 and 16 that the moulding 2 includes a lock-on system incorporating the projections 38, hole 40, push button 46 and a bar 48. Although the lock-on mechanism is not described in any detail herein, those skilled in the art will appreciate the way in which such mechanisms operate and 20 so a detailed description herein is not necessary. However, it can be seen that once the moulding 2 has been actuated as shown in figure 16 then the projections 38 and the holes 40 with which the bar 48 co- operates have moved relative to the bar 48. This means that a user is able to push the button 46 to move the bar 48 (which was previously constrained in the narrow-width portion of the hole 40) so as to prevent the

25 moulding 2 from moving back to its lock-off position as shown in figure 10, unless the lock-on switch is de-activated in known manner.

It will be appreciated by those skilled in the art that despite the lockoff mechanism 38, 40, 46, 48 preventing return of the pivoting detent 14 until such times as this lock-off mechanism is activated, if it is not activated, or alternatively when it is activated, there needs to be in place some mechanism for ensuring the return of the P-UK-CS 1093 detent 14 to its original rest position as shown in figure 12 thereby to obviate the potential for accidental re-activation of the electrical switch 44 of the angle grinder 28.

To this end, therefore, there is provided between the moulding 2 and the detent 5 14 a spring 50. In a preferred embodiment the spring is a helical compression spring and is preferably held in position by a plastic cylindrical projection 52 formed from or integrally with the moulding 2. Alternatively the compression spring could take the form of a resilient material such as a rubber block, or the like.

10 As can be seen most readily from figure 2 the cylindrical projection 52 couples with the moulding 2 at its upper end 54, thereby having a lower open end so that the spring 50 can fit around the projection 52, The lower end of the spring 50 when formed around the projection 52 is held in place therewith by virtue of the pair of arms 24 formed on the detent 14. As can be seen most readily from figures 12, 14 15 and 16, therefore, the spring 50 is sandwiched between the pair of arms 24 and the moulding 2. Thus, when the moulding 2 is moved as in figure 18 to actuate the electrical switch 44, then the spring 50 is placed under compression and thus once the user releases the moulding 2 the spring 50 acts so as to expand again to its natural rest state thereby forcing the detent 14 to pivot about its pivot point 16 into its rest 20 position as shown in figure 12.

P-UK-CS1093

Claims

5 1 A power tool actuator switch defining a pivot point about which the actuator switch may pivot during use thereof, and a pivotable detent mounted on or within the actuator switch, which pivotable detent must be actuated to allow pivoting of the actuator switch; wherein the detent is biased towards a first position which prevents pivoting of the actuator switch and characterised in that the biasing is achieved by a compression spring mounted between the actuator switch and the detent.

15
2 An actuator switch according to Claim 1 wherein the switch includes at least one depending arm for defining the pivot point.
3 An actuator switch according to Claim 2 wherein the at least one depending arm consists of a plurality of arms.
4 An actuator according to any one of the preceding claims wherein the spring is a coiled compression spring.
5 An actuator according to Claim 4 wherein the detent includes a flange for 25 providing an operating surface against which operating surface the spring acts.
6 An actuator switch according to any one of the preceding claims wherein the pivot point is defined by at least one spigot on the actuator switch.

30
7 An actuator according to Claim 6, when appendant to Claim 3, wherein each of the arms of the plurality of arms is associated with a respective spigot.

P-UK-CS 1093
8 A power tool actuator switch substantially as hereinbefore described and with reference to the accompanying drawings.
9 A power tool including an actuator switch according to any one of the preceding claims.

P-UK-CS1093