CA1221129A - Hand tool reversing switch with rotatable spaced apart resilient contacts - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Two pairs of contact strips are mounted on the respective bridge members of an integral web portion of the molded field case of a power tool or other motor-driven device. The forward ends of the contact strips are cantilever mounted and automatically engage the respective terminals on the field, as the field is inserted into the field case and is secured therein. An annular wire harness is mounted on the rear bearing boss of the field case. Spaced contacts are carried by the wire harness and engage the respective ends of the first pair of contact strips. The respective ends of the second pair of contact strips are connected to terminals on the ends of the brush shunts. In a reversing embodiment, a third pair of contact strips is mounted on the bridge, and a rotatable reversing subassembly is mounted on the rear bearing boss in lieu of the wire harness.

Description

ELECTRICAL CONNECTlûN SYâTEM FOR MOTORS

CROSS-REFERENCE TO RELATED APPLICAT101~,' The subject matter of this patent application is related to that disclosed in corresponding Canadian 5 . application Slrial No. 447,398 _ , filed on. May 8, ?~_ , for Electrical Connection System for Switches, and assigned to ~he same assignee as the present application.
This is a divisional of application 447,400, filed February 14, 19 84.

FIELD OF THE INVE~TIO~' The present invention relates to an improved system for the electrical connection of electric motors, and more particularly, to the electrical connection Or universal motors used in power tools and other devices.

BACKGROUND OF THE INVENTION

lS In power tools and related devices, the motor housing comprises a field case, which may be made from a dielectric or insulating material (such as a suitable plastic which may be injection molded for economy of manufacture). The field case may include an integral weh portion having a rear bearing boss and further having a plurality of circumferentially-spaced bridge members joining the rear bearing boss to the generally-cylindrical main portion of the field caseO The universal motor

-2-includes an armature and a field. The field is inserted within the field case and is secured therein. The armature is inserted within the field and has a shaft journaled in a bearing in the rear bearing boss. A
commutator is carried on the armature shaft, and spring~loaded brushes are slidably received in respective brush holders mounted on the field case for engagement with the commutator. With this arrangement the motor wire-up must often be conducted by hand.
Also the prior art has resorted to various forms of manually-manipulatable reversing members. For example, the reversing member may be adapted to ro~ate a hrush carrier pivotally mounted in the tool housing. Access ~o the reversing member is through an aperture in the tool housing.
While generally practical for the purposes intende~, these structures (with or without the separate reversing mechanisms) are not readily adaptable to a wide range of power tools, appliances and other motor-driven devices for standardization of manufacture and assembly. Moreover, the electrical connection of the motors within the final product inYolves various wires and connections which further delay the overall assembly time, and inhibits reali~a~ion of many beneits associated with automation of the assembly processes. This is especially important during the assembly of a compact power tool having relatively high motor performance and further having an overall "double insulated" design.

SUMMARY OF THE INVEN~ION
Accordingly the present divisional case in one aspect provides a reversing switch for an electrical device having a housing, comprising: a support member, means for rotatably --3~

mounting the support member on the housing, means formed on the housing and the support member for restric-ting the movement of the support member to thereby accommodate a limited pivotal movement of the support member relative to the device, a pair of spaced-apart reversing contacts wherein the major flat surfaces of the contacts are formed in a prescribed arc to provide a natural resiliency in the contacts, the contacts carried by the support member, each of the reversing contacts having bifurcated end sections formed in a continuation of the prescri.bed arc in end portions of the reversing contacts, two pairs of contact means, and means for mounting the two pairs of contacts on the device and in position for selective engagement, alternately, with the bifurcated sections of the respective end portions of the reversing contacts.
lS In a further aspect the present divisional provides a reversing switch for an electrical device having a housing, comprising: a support member, means for rotatably mounting the support member on the housing, means formed on the housing and the support member for restricting the movement of the support member to thereby accommodate a limited pivotal movement of the support member relative to the device, spaced-apart reversing contacts mounted within the support member and formed to provide a natural resiliency in the contacts, the housing for the device including a portion having an external annular surface, two pairs of contact elements fixedly mounted on the housing, each of the contact elements having respective end portions supported on the external annular surface of the housing portion, and the contact elements being mounted on the housing in position for alternately engaging the respective reversing contacts, the respective contact elements being wedged in a radial direction between the housing portion and the support member of the reversing switch.
In a still further aspect there is provided the method of assembling a reversing switch, comprising the steps of providing an inner annular member made from an insulating material, the inner annular member having first keying means therein, providing a pair of arcuately-formed reversing contacts, mounting the pair of reversing contacts wlthin the inner annular member, whereby the reversing contacts are spaced-apart, circumerentia.~1y with respect to each other and whereby the reversing contacts S project radially within the inner annular member, providing an outer a.nnular member made from an insulating material, the outer annular member having second keying means therein, circum-ferentlally aligning the outer and inner annular members, and moving the members axially towards one anotller, whereby the inner member is nested within the outer member, and whereby the first and second keying means are brought together thereby assuring conjoint rotation of the members.
The motor housing comprises a ~olded field case having an integral web portion including a plurali~y of circumferentially-spaced bridge members joining the rear bearing boss to the generally-cylindrical main portion of the field case. Openings (or channels) are formed in the brid8e members for ~ounting the respective contact elements therein. These contact elements are formed as bent contact strips, at least some of which are can~ilever mounted on the respective bridge membersO
These and other objects of the presen~ invention will become apparent from a reading of the following description, taken in conjunction with the enclosed d rawi ng s .

BRIEF DESCRIPTIO~' OF THE DRAh'lNGS

~ IGURE l is a side elevation of a typical power ~ool which is illus~rative of one type o~ products to which ~he 2~

teachings of the present inven~ion may be applied;
- FIGURE 2 is the circled portion of Figure 1, drawn to an enlarged scale, and wi~h parts broken away and sectioned to illustrate one e~bodi~ent of the present invention, FIGURE 3 is a rear elevation of the tool shown in Pigure 2, but with ~he rear handle cover removed, and showing an annular wire harness mounted on the rear bearing boss of the integral web portion of the field case;
FIGURE 4 is a section view, taken slong the lines 4-4 of Figure 3 and drawn to an enlarged scale, showing the armature shaft journaled in a bearing in the rear bearing boss, and further showing the brushes mounted in respective brush hvlders and engaging the co~mutator on 15 the armature shaft;
FIGURE 5 is a section view, taken along the lines 5-5 of Figure 3 and drawn to an enlarged scale, showing one of the first pair of contact elemen~s carried by the respective bridge members 9 and further showing one of the rearwardly-projecting terminals on the field assembly which automatically engage the forwardly-projecting end portion of the respective contact element when the field subassembly is inserted within the field case and is secured therein;
FIGURE 6 is a section viewg taken along the lines 6-6 o$ Figure 3 and drawn ~o an enlarged scale, showing one of the second pair of contact elements carried by the respective bridge members, and further showing a portion of the annular wire harness mounted on the rear bearing 30 boss, the respective contact on the wire harness engaging the rearwardly-projec~ing end portion of the respective contact elemen~;
FIGURE 7 is a section view, taken along the lines 7-7 of Figure 6 and drawn to an enlarged scale, and showing the respective channel-shaped bridge member for supporting one of ~he second pair of contact elements;
~ ~IGURE 8 is an exploded perspective, showing ~he integral web por~ion on the rear of the field case, the firs~ and second pairs of co~act elements~ and the wire harness to be mounted on the rear bearing boss on ~he field case;
FIGURE 9a, 9b, and gc are schematic views, some in exploded for~, showing the method of assembly of the conventional motor components in relation to a preferred em~odiment of the electrical connection sys~em of the-present invention;
FIGURE 10 is an alterna~e embodiment of the wire harness of Figure 8;
FIGURE 11 corresponds substantially to Figure 2, but shows a second embodiment of the present invention, including a reversing subassembly;
FIGUR~ 12 is a rear eleYation, ~aken along ~he lines 12-12 of Figure 11, but with the rear handle cover removed;
FIGURE 13 is a partial top perspective of the rear handle coYer assembled to the field case, showing the accessible portion of the reversing subassembly nested within a dwell în the rear handle cover;
FIGURE 14 is an exploded perspective, similar to Figure 8, but showing the three pairs of contact elements mounted on the integral web portion of the field case, and further showing the components of the reversing subassembly including the pair of spaced arcuate contacts;
FIGURE 15 is a section view, taken along the lines 15-lS of Figure 14 and drawn to an enlarged scale, and showing one of the third pair of contact elements oarried by the respective bridge member on the web portion of the field case;
FIGURE 16 is a front elevation of the reversing member, ~lookiJIg from field rearwardly towards the handle) 35 in its assembled form and drawn to an enlarged scale~ the - ~L2~

broken lines showing the respective rearwardly-projecting - end portions of the second a~d ~hird pair o contact elements for reversibly eng~ging ~he respective pair of spaced arcuate contac~s on ~he reversing subassembly~
FIGURE 17 is a section Yiew, taken along the lines 17-17 o Figure 16;
F15URE 18 is a plan layout of one of the arcuate contacts on the reversing memberD showing its longitudinally-split bifurca~ed contact portions; and . FIGURE l9a, l9b and l9c are electrical schematic diagrams, respec~ively showing one ~non-reversing) e~bodiment, an alterna~e ~reversing) em30diment in its "forward" position, and the al~ernate (reversing) embodiment in its "reverse'l position.
FIGURES 20a and 20b are electromechanical schematic dia~rams showing the operation of a double reduction drive system of the present invention in forward and reverse, re spec~ i vely .
FIGURES 21a and 21b are electromechanical schematic 20 diagrams illustrating the compensating means of the present invention in a triple-reduction transmission, in forward and reverse, respectively.

DESCRIPTION OF THE PREFERRE~ EMBODIMENT

With reference to Figure 1, there i5 illustrated a portable electric drill 10. It will be appreciated by those skilled in the art, however, that the scope of the presen~ invention is not restric~ed thereto, but that the teachings of the present invention are equally applicable to a wide variety of power tools, appliances and other electric motor driven devices~ and indeed~ to a wide variety of electric motors, per seO With this in mind, the drill 10 generally comprises a motor housing ll, a gear case 12 secured forwardly of the motor housing, a chuck 13 forwardly of ~he gear case, a trigger switch 14 -for controlling the energization of ~he tool, a rear handle cover 15 secured rearwardly of the motor housing, a pistol-grip handle 1~ depending from the motor housing, and a strain relief means 17 depending fro~ the handle, the strain relief means being assoeiated with a li~e cord (not shown) or connection to a suitable power source.
With referçnce to Figures 2-89 the motor housing comprises a field case 18 formed from a suitable insulating or dielectric ~aterial. Preferably, the field case is injection molded from a suitable plastic material having relatively high impac~ s~rength and structural rigidity, as well as good electrical insulating qualities. The field case includes a generally-15 cylindrical main portion 19 and further includes a rearweb portion ~or spider) 20 formed integrally therewith.
The web portion 20 includes an annular rear bearing boss 21, and a plurality of circumferentially-spaced inclined bridge members 22 joining ehe bearing boss to the main portion of ~he field case, as shown in Figure 8. The field case further has a rearwardly-projecting boss 23, as shown in Figure 2, and the rear handle cover is secured thereon by means of a ~astener 24.
An electric motor 25 is housed within the ield case.
~s The motor is of the universal type and încludes a stator or field subassembly 26 and a rotor or armature subassembly 27 nested therein. The field subasse~bly includes a field core or stack of laminations 28 having longitudinal passageways 29 for respective screws 30. The screws extend beyond the field st~ck, and a molded carrier 31 ~for the brushes) is piloted ~hereon. The field stack, together with the screws and brus}l carrier9 is inserted within the open forward portion 32 of ~he field c~se and is seated therein; and the screws are received in L2~

respective holes 33 in the rearward portion of the field case. As a resul~, the field subassembly i5 secured within the field case, and the brush carrier is retained between the ield subassembly and the field case~ The carrier includes rearwardly-extending brush holders 34, diametrically opposite to one another as shown in Figure 4, for receiving respective brushes 35. The brushes are resilien~ly biased by respec~ivç springs 36 re~ained within the holders Each of the brushes has a shunt wire 37; the end of each shunt is provided with a terminal 38.
The armature has a shaft 39 journaled in a bearing 40 in the rear bearing boss. The armature shaft carries a commutator 41 shown in Figures 2 and 4~ for engagement with ~he brushes. The field subassembly also includes a 15 terminal block 42 with terminal means thereon.
Preferably, the terminal means includes four terminals, one of which is shown at 43 in Figure 5. The motor field is of the two-coil type, each of the coils having two leads (not shown) which are connected to the our terminals 43 in a suitable manner.
In accordance with the teachings of the present invention, a plurality of contact elements 4S, 46 are carried on the integral rearward portion of the inslulated ~ield case. As shown in Figures 5 and 6, the respecti ve bridge members have slots or openings 44 formed therein.
Each of the openings 44 is formed in the upper portion of its respective bridge member, substantially adjacent ~o the main portion of the field case. As shown in Figure 8, first and second contact elements, 45 and 46, respectively, are received in the respective openings in the bridge members. (These eontact elements may be mounted on the housing in first and second pairs, respectively.) Each of the contact elements includes a sui~ably formed or bent contact strip. Each of ~he bridge members has a rearward ledge (or face) 47 and a forward ledge (or face) 48, adjacen~ to the respective openings and transverse theretoO Each of $he contact strips has a ~ain body portion formed with a downwardly-plojecting lanced-out tab 49 ~nd a downwardly-ben~ ledge 50. With ~his arrangemen~, and as shown more clearly in Figures 5 and 6, each contact strip may be inserted forwardly through i~s respective openings, such ~hat i~s ledge 50 engages the rearward ace 47, and such that its lanced-out tab springs down and engages ~he forward face 48, thereby axially retaining each contact strip in its respec~ive opening with respect to the respective bridge member. The contact strips are thus cantilever mounted and have forwardly-projecting ends or end portions 51. The terminals on the field are each provided with leaf-spring emale sockets 57 (or other sui~able socket ~eans) for enBagement with the respective forward ends of the contact strips, as shown m~re clearly in Figures 5 and 6, thereby making electrical contact be~ween ~he firs~ and second pairs of contact strips 45) 46 and the coils on the field subassembly. This engagement and electrical connection between the contact strips and the field terminals occurs automatically upon the insertion of the field within the field case and the securing of the field ~herein. The first pair of contact strips have respective cantilevered 25 rearwardly-projecting ends or end portions 531 as shown in Figure S, The second pair of contact strips 46 have respective downwardly-inclined rearward portions ~4 supported in complementary channels 55 formed on the respective bridge members, as shown in Figures 6 and 7.
These inclined rearward portions have respective rear ends 56~ ben~ thereto, and disposed adjacent to the external annular surface of the rear bearing boss.
A wire harness 57 is provided in accordance with the further teachin~s of the present invention. The wire harness 57 is made from an insulating material (such as a ~uitable molded plastic~ and is annular in form, although it ~ay take other forms as well, depending upon ~he shape of the motor housing. Spaced contacts 58 are mounted on ~he wire harness and are connected to respective 5 conductors 59 carried thereon. The annular wire harness is receivçd on the rear bearing boss and ~ay be press-fitted thereon. As a result, ~he contacts on ~he wire harness enga~e the rearward ends of the second pair of contact strips, making electrical connection thereto, as the rearward ends of the contact s~rips are wedged between the bearing boss and the contacts on the wire harne$s tas shown in Figures 6, 9b and 9c). The wires on the wire harness are then connected to the switch ~in a conventional manner), which is ultimately connected to a source of elec~rical energy.
Thus, it will be appreciated that the first and second pairs of contact strips 45 and 46, respec~ively, in co~bination with the wire harness 57, ~reatly facilitate the connection of the field to the brushes and ~o ~he switch leading to the power source. The formed contact strips are easily inserted into the integral web portion of the field case; the terminals on the field automatically engage the respective con~act strips when the field is inserted into the field case and is secured ~5 therein; the terminals on ~he brush shunts are readily slipped over two of the contact strips and connec~ed thereto; the wire harness is ~ounted on the rear bearin~
boss for automatic engagement with the remaining two contact strips on the web, and finally, the wires on the wire harness are connected to the switch in the usual manner. With this arrangement, a plethora of loose wires is eliminated; assembly and electrical connection ti~e are subs~antially reduced; and the motor connections are standardized for a wide variety o power tools, appliances or other motor-driven devices. Thus opportunities for ~ 2 ~

automated asse~bly are enhanced~ since ~ost of the ~assembly ~otions described above are in directions parallel to the axis of ~he motor. Thus each brush shunt is a first means for connec~ing the rearward end portions of one of the first or second cont~ct elements (or pairs of contac~ elements) to at least one of ~he ~rushes; and the wire harness is a second means for connecting the rearward end portion of the o~her of the contact elements (or pairs of elements) to a source of elec~rical energy.
- With reference to Figures 9a9 9b, and 9c, the advantages and benefits of the impro~ed apparatus and method of the present invention will be readily appreciated. As shown in Figure 9a, the contac~ strips 45 and 46 are mounted on the rearward portion of ~he field case 18, being slipped into their respec~ive openings 44 in the bridge members 22. The mounting scre~s 30 are slipped into the field subassembly 26, extending therethrough, and the brush carrier 31.The field subassembly ~with the brush carrier) is inserted through the open forward portion 32 of ~he field case, is sea~ed therein, and the screws are driven into the field case.
In this manner ~he four terminals 43 on the field automatically engage (and hence make electrical connection) to the cantilevered forward ends 51 of the ~our contact strips 45, 46, as shown in Figures 6, 9b, and 9c. The armature 27 is inserted within the field, such that its commutator-end bearing 40 is recei~ed within the rear bearing boss 21, and when the armature i5 in placeg the brushes 35 are released to engage the commu~tor 410 The brush shunt terminals 38 are connec~ed to the cantilevered rearward ends 53 of the first pair of contact strips 45. The wire harness 57 is mounted on the rear bearing boss 21, such that its contacts 58 are wedged against (and hence ~ake electrical connection with) the

3~ resr ends 56 of the remaining (second) pair of contact strips 4~. The wires 59 on the wire harness 57 are t~en ~connected ~o the switch.
With reference to Figure 10, a modified wire harness 57' includes means for retaining the annular harness or member on the housing, including a pair of subs~antially diametrically opposed resilient latch members 60 formed integrally therewith. These latch ~embers define ~atch apertures 61 and project forwardly of the wire harness.
The latch members 61 are sufficien~ly flexible, such that ~he latch member may be flexed slightly (outwardly) as the wire harness 57' is slipped over the rear bearing boss 210 The respectiYe latch apertures 61 engage latch bosses 61a on the bearing boss (as shown in Figure 8) and the wire harness 57t is retained on the bearing boss with a "snap ac~ion". Moreover, if desired, the wire harness 57' may be provided with a suitable key (not shown) for cooperation with a corresponding keyway on the bearing boss (again, not shown) to 2ssure the proper circumferential position of the wire harness on the bearing boss for proper engagement between the contacts 58 and the ends 56 on the second pair of contact strips 46.
Moreover, and again if desired, the shape of the wire harness could be other than annular, and could be f ixedly mounted elsewhere within the housing.
With reference to Figures 11-1~, a second embodiment of the present inYention is provided. In this second embodiment, a reversing subassembly 62 is used in lieu of a wire harness, and a ~hird bent contact strip 63 is mounted on the bridge as shown in Figures 14 and 15.
~Again, the third cont~ct strip may be ~ounted on the housing in third pairs of contact elements.) The reversing subassembly 62 includes an ou~er (or first) reversing member 64 which is a support member preferably made from an insulating material 9 such as a suitable molded pl~stic. This first reversing member 64 has means ~2~

for rotatably retaining the reversing subassembly on the rear portion ~f ~he housing, including a resilient plug 66 shown in Figure 17, and which is engaged by a portion of the handle 15~ as shown in Figurç 11. The resilient plug 66 therefore ac~s as a vibration isolation ~eans between the handle and the res~ of the tool. In this manner, the outer reversing member is mounted on the bearing boss for a limited rotary or pivoted movement thereon, but is precluded from axial dislodgement therefrom.
An inner (or second) reversing member 68 is nested within the outer reversing memberp as shown in Figures 16 and 17, and is keyed thereto (as at 69) for conjoint limited rotary movement therewith. This inner reversing member is also made from an insulating material, such as a 15 suitable molded plastic. A pair of curved contact means, or spaced-apart arcuately formed reversing contaets 70 are carried by the inner reversing member, and are ~ounted transverse to the plane of the reversing member. These reversing contacts 70, as shown in Fi~ure 18, each have a cen~ral portion 71 and longitudinally-split bifurca~ed contact-engaging ends 72 and 73, respectiYely. Each of these ends are in turn provided with respective dimples 74 for engagement with the respective rearwardly-projecting ends of the second and third pair of cont~ct s~rips, 46 and 63~ respectively, as shown in Figure 16. Also as shown in Figure 16, this bifurcated configuration is part of a ~eans for compensating for tolerance buildup associated with the po~ential differenees in radial distances Rl, R2 to the respective ends 56, 76 of the cantilever-mounted contacts 46, 73. ~here Rl does not equal R2, a single cantilever-mounted curved contact strip could enBage strip 46, and be levered out of engagement with strip 63. Therefore by splitting contact strip 70 into two strips of different lengths, the strips are self~biased, more or less independently) against contact elements 46, 63, thereby taking up variations in their respectiYe radial distances from the axis "A" of the subassem~ly, &nd accommodating stress due to the amount of deflection in the free ends of the strips. Further, and 5 as shown in Figure 14~ the rearwardly-projecting ends 53 of the iEirst pair of contact strips 45 are connected to the switch ( in a suitable manner); the forward ends 75 of the third pair of contact strips 63 (shown in Figures 14 and 15) are connected to the brush shunt terminals 38; and the forwardly~projecting ends of ~he first and second pairs of contact strips 45 and 469 respectively, automatically engage the four ~erminals 43 on the field (as in the first embodiment of Figures 2-8)~ The rearwardly-projec~in~ respective ends 56 and 76 of the second and third pairs of contact strips, 46 and 63, are alternately connec~ed to the arcuate reversing contacts 70 for reversing the electrical connections be~ween the field and the armature for reversing the motor rotation in the conventional manner. Thus the reversing subassembly includes reversing means for selectively interconnecting the respective rearward end portions of the second and third pairs of contact elements ~o change the direction of rotation of the armature. However it should be noted that reversing subassembly 62 need not include discrete reversing members 64, 68. Instead, members 64, 68 may be integrally ~olded as one unit. Thus the reversing subasse0bly is yet another for~ of the first means for connecting the rearward end portions of one of the first or second contact ele~ents (or pairs of contact elements) to ~t leas~ one of ~he brushes.
With reference again to Figures 12-149 the reversing subassembly 62 has a radially-extending integral por~ion or switch operator 77 which is formed with a generally oval aperture 78 wi~hin which the rearwardly;projectin~
boss 23 on the field case is received. The integral ~2~

portion 77 is further proYided with a ~anually-~anipulate~
-portion or serrated reYersing bu~ton 79 which passes through an opening 80 in the rear switch cover and is nested within a dwell 81 therein tas shown in Figure 13).
The reversing subassembly also has a downwardly-projecting integral tab 82 for interlocking engagemen$ with the switch, thereby precluding movement of the reversing subassembly in the "on" position of the switch. As shown in Figure 17,`if desired9 a-fel~ washer 83 may be tr~pped between the reversing subassembly and the field case t.o minimize the flow of dirt or dus~ particles to the reversing contacts and the rearwardly-projecting ends of the respective contact s~rips.
With reference eo the schematic diagrams of Figures l9a, l9b, and l9c, the electrical interconnection of the present invention will be further appreciated. In the non-reversing embodiment of Figure 19A~ the firs~ contact elements 45 connect the field coils 84, 85 to the brushes 35 on the armature 27, and the second contact elements 46 connect the field coils to the switch 14 (Yi8 the wire harness 57) to the power source 8~. In the reversing embodiment shown in Figures l9b and 19c, the first contact elements 45 now connect the field coils 84, 85 to the switch 14~ and the second contact elements 46 and third contact elements 6~ reversibly cGnnect the field coils ~4, 85 to the brushes 35 via the reversing subassembly 62.
The reversing subassembly has two alternate positions; the first or "forward" postion is shown in Figure l9b, and the second or "reverse" position is shown in Figure l9c.
Another advantage of the electrical interconnection and reversing systems of the present invention is the creation of a drive system having compensating means for csusing the output shaft to rotate in a predetermined direction responsive to movement of the reversing switch from a first (forward) position to a second (reverse) ~.2;2~

position, for any given number of trans~isslon drive elements. This ea~ure is illus~rated in Figures 20a and 20b, showing a double-reduction tr~nsmission 100, and in Figures 21a and 21b, which illustrate a ~riple-reduction transmission 102~
The drive system schematically shown in ~igure 20a includes armature shaft 39, which rotates in one directio indicated by arrow 104 ~correspondin~ to the current direction indicated by arrow 106), when the reversin~
swi~ch is in its "forward" or first position. The drive system further includes "N" number of drive elements 108 which form a ~ransmission connecting the armature shaft 39 to the output shaft 110, which rotates in a predetermined direction indicated by arrow 112. Referring now to Figure 20b, when the reversing switch is moved to îts second or "reverse" position, the current flow 106 is reversed, thereby reYersing the armature shaft direction of ro~ation 104 and the ou~put shaft direction of rotation 112.
HoweYer~ i~ is now necessary to address the problem posed when the drive system for a particular application includes "N ~ 1", "N ~ 2" or another number of drive elements 108, since changing the number of drive elements from one application to another will result in changing the direction of rotation 112 of the output shaft 110 for a given direction of current flow, Also it is desirable to maintain the orientation of the "forwardl' and "reverse"
positions of switch reversing button 79 with respec~ to the housing configurations, ~5 shown in Figure 13, whether the particular power tool or other applicstion contains a 3~ double- or triple-reduction transmission. The solution to the problem is the compensating means shown in Pigures 21a and 21b, and in Figure 16. Referring now to Figure 169 an alterna~e keyway 69a is formed at diametrically opposi~e points on the inner (reversing) member 68, and i5 spaced cireumferentially approximately 25 from keyway 69.

~2~

Recalling that Figure 16 is taken looking rearwardly from the field, and that Figures 20a, 20b, 21a and 21b are taken looking forwardly ~oward the field~ it can be apprecia~ed that if the subassembly of curved contact strips 70 and (inner) reversing member 68 is first rota~ed 25, and then assembled so that alternate keyway 69a is now located at the position formerly occupied by keyway 69, the curved contact strips 70 will therefore be selectively oriented or locatable wi~h respect to the respective contact elements 56, 76, (and to the first ~nd second switch positions) as shown in Fi~ures 21a and 21b.
The result is a change in direction of current flow, as seen when comparing Figure 21a with Figure 20a, and Figure 21b with Figure 20b. Therefore when it is desired to use the subject invention in conjunction with a triple-reduction reversing power tool instead o a double-reduction reversing power tool, the tool is assemblet with ~ reversing subassembly utilizing keyway 69a as just described7 thereby yielding the same predetermined direction of ro~ation for output shaft 110 as was generated in the double-reduction system. This can be seen by again comparing ~igure 21a with Figure 20a ~ and Fi~ure 21b with Figure 20b. It can be appreciated that this feature of the present invention is ~pplicable not only to drive systems u~ilizing gear trains, but to belt drives, chain drives, rollers, ~hreads, and others.
However it should be noted then if the reversing subassembly 62 does not include ~wo discrete members 649 68, but rather is composed of a single integrally-molded ~ember, compensation for variations in the number of transmission elements can be effected by molding two types of reversing members, such that one type orients the reversing contacts 25 with respect to ~he other type.
Thus it will be ~ppreci~ted that the first and second pairs of contact elements (s~rips 45 and 46, ~espectively) ~9~

are used in both embodiments, that is, the non-re~ersing embodiment of Figures 2-B, and reversin~ smbodiment of Figures 11-18. In ~he non-reversing emebodiment, ~he wire harness 57 ~or 57' ) is used; and in the reversing 5 embodimen~, ~he reversing subassembly 62 is used in addition to the third pair of contact elements (strips 63). Preferably9 both the wire harness 57b and the reYersing subassembly 62 are mounted on the re~r bearing boss. In each case~ the pairs of respectiYe contac~s 58 10 and 70 carried by the wire harness and reversing subassembly9 respectively automatically engage (and make electrical contact with~ the respectiYe rearward ends of the appropriate contact elements. The contact elements are mounted on the integral web portion of the field case;
and in each case, the forward ends of two pairs of contact elements automatically engage (and make electrical contact with) the four terminals on the field, when the fleld is seated within the field case and is secured therein. As a result, the electrical connections for the motor are greatly simplified; standardiza~ion is assured for a wide variety of motors, both reversing and non-reYersing;
production economies are re~lized; and the quality, relisbility and serviceability of the end product are substan~ially improYed.
Obviously, many modifications ~ay be made without departing from the basic spirit of the presen~ invention.
Accordingly, it will be appreciated by those skilled in the art that within the scope of the appended claims 9 the inYention may be practiced other ~han has been specifically described herein.

Claims (14)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A reversing switch for an electrical device having a housing, comprising: a support member, means for rotatably mounting the support member on the housing, means formed on the housing and the support member for restricting the movement of the support member to thereby accommodate a limited pivotal movement of the support member relative to the device, a pair of spaced-apart reversing contacts having major flat surfaces of the contacts formed in a prescribed arc to provide a natural resiliency in the contacts, the contacts carried by the support member, each of the reversing contacts having bifurcated end sections formed in a continuation of the presecribed arc in end portions of the reversing contacts, two pairs of contact means, and means for mounting the two pairs of contacts on the device and in position for selective engagement, alternately, with the bifurcated sections of the respective end portions of the reversing contacts.

2. The reversing switch of claim 1, wherein: .
the support member including a first portion and a second portion, and further comprising the reversing contacts carried by the first portion, means on the first portion for locating the pair of reversing contacts thereon, and means for keying the first and second portions together to place the reversing contacts in predetermined relationship to the contact means.

3. The reversing switch of claim 1, wherein:
the support member being rotatable in a plane, and the reversing contacts being mounted transverse to said plane.

4. A reversing switch for an electrical device having a housing, comprising: a support member, means for rotatably mounting the support member on the housing, means formed on the housing and the support member for restricting the movement of the support member to thereby accommodate a limited pivotal movement of the support member relative to the device, spaced-apart reversing contacts mounted within the support member and formed to provide a natural resiliency in the contacts, the housing for the device including a portion having an external annular surface, two pairs of contact elements fixedly mounted on the housing, each of the contact elements having respective end portions supported on the external annular surface of the housing portion, and the contact elements being mounted on the housing in position for alternately engaging the respective reversing contacts, the respective contact elements being wedged in a radial direction between the housing portion and the support member of the reversing switch.

5. The reversing switch of claim 4, wherein:
the support member including a first portion and a second portion, and further comprising the reversing contacts mounted within the first portion, means on the first portion for locating the reversing contacts thereon, and means for keying the first and second portions together to place the reversing contacts in predetermined relation-ship to the contact means.

6. The reversing switch of claim 4, wherein:
the support member being rotatable in a plane, and the reversing contacts being mounted transverse to said plane.

7. The reversing switch of claim 4, wherein:
each reversing contact including a generally arcuate member made from relatively thin-gauge metal, and the arcuate member including respective end portions.

8. The reversing switch of claim 7, wherein:
the end portions being longitudinally slotted to form bifurcated sections.

9. The reversing switch of claim 8, wherein:
one of the bifurcated sections of one end portion being longer than the other bifurcated section of the one end portion.

10. The reversing switch of claim 7, wherein:
the arcuate member including a 'U'-shaped intermediate portion joining respective end portions.

11. The reversing switch of claim 10, wherein:
the respective end portions of the arcuate member describing an arc, and the 'U'-shaped intermediate portion being located substantially radially outwardly of said arc.

12. The reversing switch of claim 7, wherein:
the end portions including bent contact-engaging surfaces for engagement with electrical contacts of the electrical device.

13. The reversing switch of claim 12, wherein:
the respective end portions describing an arc, and the bent contact-engaging surfaces describing arcuate portions located generally radially inwardly of said arc.

14. The method of assembling a reversing switch, comprising the steps of providing an inner annular member made from an insulating material, the inner annular member having first keying means therein, providing a pair of arcuately-formed reversing contacts, mounting the pair of reversing contacts within the inner annular member, whereby the reversing contacts are spaced-apart, circumferentially, with respect to each other and whereby the reversing contacts project radially within the inner annular member, providing an outer annular member made from an insulating material, the outer annular member having second keying means therein, circumferentially aligning the outer and inner annular members, and moving the members axially towards one another, whereby the inner member is nested within the outer member, and whereby the first and second keying means are brought together, thereby assuring conjoint rotation of the members.