Tool with manual spindle lock

Abstract: A power tool has a manual spindle lock which includes a first locking member to couple with a gear of the power tool drive train. The locking member includes a first cam member. A second cam member is coupled with the first cam member. The second cam member is movable between first and second positions. In the first position, the locking member is disengaged from the gear and in the second position the locking member engages with the gear to prohibit driving of the output spindle of the power tool.

Description: The present invention relates to power tools and, more particularly, to power tools such as power screwdrivers with manual spindle locks. Varying torque or force is applied to a fastener as the fastener, such as a screw or bolt, is advanced into or removed from an anchoring position. Ordinarily, large forces are required to set the screw during installation or to initially break loose the screw during removal. In small power tools, difficulties are encountered in generating these large forces. The underlying limitation of these tools is the motor horsepower. This problem is further aggravated in battery operated tools. In battery operated tools, to have sufficient electrical capacity from the battery to operate a high torque power tool, a large heavy size tool is required. Thus, lightweight self-contained battery operated tools are limited in the amount of torque which can be produced. To alleviate the shortcomings, the prior art teaches conventional screwdrivers being utilized with power tools to deliver the high torque. Also, elaborate drive trains may be associated with the power tool to deliver the increased torque. However, this lowers the drive speed. Further, different types of shaft locks have been provided. The shaft locks provide the powered screwdriver with the high torque feature of a manual screwdriver when required. Thus, it is desirable to have a power tool with a manual spindle lock to be utilized in high torque situations. DE 4128651 discloses an electric screwdriver in which an actuating member on the housing is movable between a manual screwing position in which a first locking member is brought into engagement with a gear to allow rotation of an output shaft of the screwdriver in a first direction only, and a manual unscrewing position in which a second locking member is brought into engagement with the gear to allow rotation of the output member only in a second direction, opposite to the first direction. It is an object of the present invention to provide a compact lightweight power tool with conventional shaft speeds that is capable of supplying sufficient torque and includes a manual spindle lock which may be utilized when high torque situations exist. The present invention provides a simple cost-effective design to provide a spindle lock with a power tool such as a compact power screwdriver. According to an aspect of the present invention, there is provided a spindle lock for a power tool as set forth in claim 1. According to another aspect of the present invention, there is provided a power tool comprising:- a housing; a motor in said housing; a power source coupled with said motor; an activation member coupled with said motor and power source for energising and de-energising said motor; an output spindle coupled with said motor; an output gear coupled with said output spindle; and a spindle lock as defined above. The present invention will now be described, by way of example only, and with reference to the accompanying drawings, of which: Figure 1 is a perspective view of a power tool in accordance with the present invention. Figure 2 is a cross-section view of Figure 1 along line II-II thereof. Figure 3 is a cross-section view like Figure 2 in an engaged position. Figure 4 is a perspective view partially in cross-section of the power tool of Figure 1. Figure 5 is an exploded view of the power tool of Figure 1 partially in section. Figure 6 is a view like Figure 5 of an alternate embodiment of the present invention. Figure 7 is a view like Figure 5 of another embodiment of the present invention. Turning to Figure 1, a power tool such as a power screwdriver is illustrated and designated with the reference numeral 10. The power tool 10 includes a housing 12 with a motor housing portion 14 and a gear housing portion 16. A motor 18 is housed within the motor housing portion 14 and a gear train 20 is housed within the gear housing portion 16. An output spindle 22 is coupled with the gear train 20 and is driven by the motor 8. Also, a battery 24 is electrically coupled with the motor 18 and is positioned within the motor housing 14. A spindle locking device 30 is coupled with the housing as will be described herein. The power tool 10 includes an activation switch 32 such as a toggle switch for energizing and de-energizing the motor. The switch 32 is connected between the battery 24 and the motor 18. Upon energizing the motor 18, the pinion gear 34 at the end of the motor shaft 36 is rotated. The pinion gear 34, in turn, rotates a first set of planet gears 38 which, in turn, rotate sun gear 40. Sun gear 40 in turn rotates a second set of planetary gears 42 which, in turn, rotate the output carrier gear 44. The output carrier gear 44 is coupled with the output shaft 22. The gear housing portion 16 includes teeth 46 peripherally positioned on the inner surface of the gear housing portion 16. The teeth 46 mesh with the first and second set of planet gears 38 and 42. The spindle lock 30 engages and disengages the output gear 44 which locks the gear train 20 to enable the power tool to be used manually. The spindle lock 30 includes a first member 50 and a second member 52. The first member 50 includes an annular or ring member 54 with a plurality of projecting cantilevered fingers 56. The annular member 54 includes outer circumferential teeth 57 to couple with teeth or splines 46 on the inner peripheral surface of the gear housing portion 16. The annular member 54 has internal teeth 60 which mesh with the teeth 62 of the output carrier gear 44. The annular member 52 is open at the tooth end and has a radial wall 64 partially closing the other end of the annular member. The radial wall 64 has a central opening 66 which is positioned around the spindle housing portion 68 of the gear housing portion 16. The projecting fingers 56 extend from the radial wall 64. The fingers 56 include cam elements 70. The cam elements 70 are illustrated as projecting pins. The projecting fingers 56 with the cam elements 70 are generally unitarily formed with the annular member 54. The first member 50 may be formed from a plastic or metallic material. The second member 52 is positioned around the projecting members 56 and the spindle housing 68. The second member 52 has a ring portion 72 and an end wall 74 extending radially inward from the ring 72. The radial wall 74 has a central opening 76 which is positioned around the spindle housing 68. A clip ring or washer 78 maintains the second member 52 onto the gear housing portion 16. The ring 72 includes an interior peripheral surface 80. The interior peripheral surface 80 includes a pair of parallel ribs 82, 84 which define a cam slot 86. The ribs 82 and 84, while parallel to one another, define a helical path such that the ribs 82 and 84 move away from the radial end wall 74 along their peripheral path. Accordingly, the cam slot 86 likewise moves away from the radial wall 74 along a helical path. Cam elements 70 fit within the cam slot 86. Thus, as the ring 72 is rotated, the cam elements 70 are moved along the helical path away from the radial wall 74. The cam elements 70 move axially. Accordingly, the extending fingers 56, as well as the annular member 54, move axially. As the annular member 54 moves axially, the teeth 60 engage with the teeth 62 of the output carrier gear 48. This is best seen in Figures 2 and 3. Thus, as the teeth 60 engage the output carrier gear teeth 62 the drive train 20 is locked. This is due to the fact that the outer teeth 56 of the annular member 54, which slide in teeth 46, are fixed against rotation in the gear housing portion 16. Thus, the power tool may be used in a manual position. Turning to Figure 6, a second embodiment of the present invention is shown. In Figure 6, a spindle lock 30' is illustrated. The elements which are the same as those previously disclosed are identified with the same reference numerals. The difference between the above described spindle lock and the spindle lock of Figure 6 is that the cam elements 70 are partial thread members 70' which mate with partial thread elements 82' of the second member 52. Thus, as the second member 52 is rotated clockwise and counter-clockwise, the threads 70' move along a helical path towards and away from the radial wall 74 which, in turn, axially moves the annular member 54 engaging and disengaging annular member teeth 60 with output gear 62. Thus, the spindle lock 30' operates similarly to the spindle lock 30 described above. Turning to Figure 7, a third embodiment of the present invention is shown. In Figure 7, a spindle lock 30" is illustrated. The elements which are the same as those previously disclosed are identified with the same reference numerals. The difference between the above-described spindle lock and the spindle lock of Figure 7 is that the first member does not include a large annular member with outer circumferential teeth which would couple with teeth 46 of the inner periphery surface of the gear housing portion 16. The first member 50' includes projecting members 56 with cams 70 which are pins. The annular member 54" is a circular ring. The end surface 57" would frictionally engage the gear carrier 44 like that illustrated in Figure 3. Thus, the frictional contact between the end face 57" and the output carrier 44 would prohibit rotation of the output carrier as well as the gear train to manually lock the gear train. Also, the surface 57" may include a plurality of recesses (shown in phantom) which would receive projections from the output carrier 44 (not shown) to effectively connect the ring 54" with the output carrier 44.

Claims: A spindle lock for a power tool comprising a housing (12), a motor (8) in said housing, a power source (24) coupled with said motor, an activation member (32) coupled with said motor and power source for energising and de-energising said motor, an output spindle (22) coupled with said motor, and an output gear (44) coupled with said output spindle, the spindle lock comprising:- a first member (50) at least partially surrounding said output spindle including a first cam member; and a second member (52) including a second cam member engaging said first cam member (50) and having an actuation member; characterised in that the first member (50) has a hollow cylindrical portion defining a wall with an inner and an outer surface which is coupled with said first cam member; the spindle lock further comprises a mechanism on said wall adapted to engage a drive train including said output gear (44) of the power tool; wherein movement of said actuation member between first and second positions in use causes axial movement of said first member (50) relative to said output spindle (22) between a disengaged position in which said first member (50) is disengaged from said output gear (44) and an engaged position in which said first member (50) engages said output gear (44) to prevent driving of said output spindle (22). A spindle lock according to Claim 1, wherein said first member (50) inner surface includes teeth (60) for engaging the drive train and said outer surface includes teeth adapted for engaging a housing portion. A spindle lock according to Claim 1 or 2, wherein said first cam member includes a cantilever portion (56) extending from said hollow cylindrical portion and a cam element (70) on said cantilever portion. A spindle lock according to any one of Claims 1 to 3, wherein said first cam member includes a plurality of cam elements (70). A spindle lock according to Claim 4, wherein said mechanism includes a friction end face (57") for engaging said drive train. A spindle lock according to Claim 5, wherein said friction end face (57") includes at least one recess. A spindle lock according to any one of the preceding claims, wherein said actuation member has an annular body adapted to surround the output spindle and rotatable between the first and second positions. A spindle lock according to any one of the preceding claims, wherein said first and second cam members comprise a pin (70) in a helical slot (86) respectively. The spindle lock according to any one of claims 1 to 8, wherein said first and second cam members comprise partial threads (70, 86). A power tool (20) comprising:- a housing (12); a motor (11) in said housing; a power source (24) coupled with said motor, an activation member (32) coupled with said motor and power source for energising and de-energising said motor; an output spindle (22) coupled with said motor; an output gear (44) coupled with said output spindle; and a spindle lock according to any one of the preceding claims. A power tool according to Claim 10, wherein a drive train is coupled between said motor (11) and said output spindle (22) for driving said output spindle, said drive train including said output gear (44) and a stationary gear housing (16) surrounding said drive train for co-operating with said drive train. A power tool according to Claim 11, wherein said first member (50) couples with said gear housing (16). A power tool according to Claim 12, wherein said first member (50) includes teeth (46) meshing with teeth in said housing and includes teeth for engaging teeth on said output gear (44). A power tool according to any one of claims 10 to 13, wherein said first cam member includes a projecting member received in a slot in said second cam member. A power tool according to any one of claims 10 to 14, wherein said second cam member is rotatable and axially moves said first cam member on said output spindle (22). A power tool according to any one of claims 10 to 15, wherein said first member (50) includes a gear ring (54) having teeth (57) on an interior surface of said ring and at least one tooth on the exterior of said ring, at least one finger projecting from said ring, said finger engaging said second cam member (52). A power tool according to Claim 16, wherein said first cam member comprises a pin (70). A power tool according to Claim 16, wherein said first cam member comprises a partial helical thread (70'). A power tool according to any one of claims 10 to 18, wherein said second member (52) includes a hollow cylinder portion with a helical cam slot on an interior peripheral surface of said cylinder portion, said cam slot receiving said first cam member. A power tool according to Claim 19, wherein said cam slot is defined by partial helical threads (82'). A power tool according to any one of claims 10 to 20, wherein the power tool is a screwdriver. A power tool according to any one of claims 10 to 21, wherein said first member (50') includes a ring having a friction surface (57") for engaging and disengaging said output gear and at least one finger (56) projecting from said ring, said finger being adapted to engage said second cam member. A power tool according to Claim 22, wherein said friction surface (57") includes one or more recesses for engaging and disengaging said output gear (44).

Inventors: FUNG CHI HO, LAM KAR LOK, SMITH ROGER Q, TONG CHI KIN, FUNG, CHI HO, LAM, KAR LOK, SMITH, ROGER Q., TONG, CHI KIN
Applicants: BLACK & DECKER INC, BLACK & DECKER INC.
Application year: 2000
Main classification: B25B21
IPC codes: B25B21, B25F5