US 3809168 A
A driven shaft carries a ring gear having an annular formation of teeth adapted for ratcheting engagement with an annular series of fixed teeth. When the shaft is moved inwardly of the tool housing as the result of contact of the drill bit with the work, these teeth are brought into engagement to provide a hammering action. A spindle has one end thereof rotatably mounted in a bore formed in the shaft and has the other end thereof supporting a drill chuck. A coupler sleeve is axially slidable for being located in three predetermined positions; this coupler sleeve transfers rotation from the shaft to the spindle in two of its three axial positions thereby defining a drilling mode and a combined hammering and drilling mode. In the third axial position of the coupler sleeve, the same abuts a thrust formation and prevents engagement of the ratcheting teeth thereby to define a hammering mode of operation. The sleeve is axially positioned by manually operated cam means.
Description (OCR text may contain errors)
United States Patent 1191 Fromm [451 May 7,1974
[ HAMMER DRILL  Inventor: Walter James Fromm, Chicago, Ill.  Assignee: Skil Corporation, Chicago, Ill.
 Filed: Apr. 23, 1973  Appl. No.: 353,562
52 us. Cl. 173/13, 173/48 Primary Examiner-Ernest R. Purser Attorney, Agent, or FirmMcDougall, Hersh & Scott  ABSTRACT A driven shaft carries a ring gear having an annular formation of teeth adapted for ratcheting engagement with an annular series of fixed teeth. When the shaft is moved inwardly of the tool housing as the result of contact of the drill bit with the work, these teeth are brought into engagement to provide a hammering action. A spindle has one end thereof rotatably mounted in a bore formed in the shaft and has the other end thereof supporting a drill chuck. A coupler sleeve is axially slidable for being located in three predetermined positions; this coupler sleeve transfers rotation from the shaft to the spindle in two of its three axial positions thereby definingja drilling mode arid a combined hammering and drilling mode. In the third axial position of the coupler sleeve, the same abuts a thrust formation and prevents engagement of the ratcheting teeth thereby to define a hammering mode of operation. The sleeve is axially positioned by manually operated cam means.
6 Claims, 4 Drawing Figures HAMMER DRILL BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to power tools and more particularly to power tools adapted selectively to operate in a hammering mode, a drilling mode and a combined hammering and drilling mode. Such tools are used primarily for working on concrete and masonry structures.
2. The Prior Art It is known in the prior art toprovide so-called rotary hammers or hammer drills which are capable of rotating a drill bit and simultaneously imparting repeated axial blows to the bit. Some forms of these prior art power tools are provided with means to enable the operator of the tool to select a rotating or drilling only mode of operation as well as a hammering only mode of operation. This selective operation may be achieved by providing different working tool elements which, by reason of their amount of insertion within the tool and by reason of their external shape, cooperate with the rotating and hammering elements of the power tool to provide the selected modes of operation.
In other forms of prior art power tools which do not employ different elements to obtain the selected modes of operation, clutches and/or gearing are provided to allow the operator to select two or more modes of operation. An improvement over this type of prior art FIG. 2 is a fragmentary sectionef the tool of FIG. 1 showing the parts positioned'for operating in the combined hammering and drilling mode;
FIG. 3 is a section taken along-the line 3-3 of FIG. 1; and
FIG. 4 is a developed plan view of the cam formations for positioning the camming collar in its axial positions.
DESCRIPTION OF A PREFERRED EMBODIMENT Referring primarily to FIG. 1, the power tool or hammer drill includes a casing or housing shell 10. It will be. understood that this power tool includes a suitable source of power, such as an electric or pneumatic motor, for powering a drive shaft 1 1. This drive shaft is en gaged with the teeth 12 of a ring gear 13 by a suitable reduction gear train indicated only generally by broken lines 14 and 15.
The ring gear 13 is mounted on a shaft 16 for rotating the latter in response to rotation of the ring gear. This shaft is rotatably mounted in a bearing sleeve 17, the latter being received in a bore 18 formed in a housing portion 10a. The ring gear 13 has an annular formation 19 secured thereto, as by means of a plurality of fasteners 20; this annular formation includes an integral anpower tool is shown in the copending application of John S. Jarecki, Ser. No. 284,738, filed Aug. 30, 1972, and assigned to the assignee of the present invention. With the use of the hammer drill disclosed and claimed in that copending application, hammering only, drilling only and combined hammering and drilling are achieved by selectively positioning a sleeve in three axial positions.
SUMMARY AND OBJECTS OF THE INVENTION The present invention relates to a hammer drill of the type shown in the aforementioned .larecki application and constitutes an improvement over the construction shown therein.
A primary object of the present invention is the provision of a new and improved hammer drill capable of being selectively conditioned for operating in a hammering only mode, a drilling only mode, and a combined hammering and drilling mode, in response to manual rotation of a camming collar.
Another object of the presentinvention is the provision ofa hammer drill of the type described which includes a coupler sleeve axially positioned in response to operation of the camming collar, which sleeve cou ples the drill chuck supporting spindle to the drive shaft for two of the three modes of operation, and which coupler sleeve prevents interengagement of the ratcheting teeth for the third mode of operation.
These and other objects and advantages of the present invention will become apparent from the following specification disclosing a preferred embodiment shown in the accompanying drawings.
DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial side elevation and partial vertical section of a power tool embodying the present invention, the various parts being shown for operating in the hammering only mode;
nular series of ratcheting teeth 21. These ratcheting teeth are normally in spaced confronting relationship with a complementary series of ratcheting teeth 22, the latter being integral with a ring formation 23 secured to a housing plate 24, as by means of a plurality of fasteners 25.
The housing 10 includes a bore 26 receiving a bearing hub 27. This hub journals one end of a spindle 28. A coil spring 30 encircles the spindle 28 and has its opposite ends abutting the hub 27 and the inner end of the shaft 16 for urging the latter outwardly or to the right as seen in FIG. 1. Thus, this spring 30 acts to urge the ratcheting teeth 21, 22 apart but permits engagement of these teeth as will be explained hereinbelow.
The forward end of the shaft 16 receives a bearing sleeve 32; this sleeve journals the forward portion of which flange has a plurality (preferably four) of notches or keyways 35. r
The spindle 28 includes an enlarged cylindrical portion 36 having a plurality (preferably four) of axial grooves or keyways 37. The spindle is further defined by another cylindrical portion 38 mounting a drill chuck 40. This drill chuck may be of conventional construction and therefore requires no further explanation herein.
A washer 42 is mounted on the spindle portion 38 and abuts the annular surface 43 formed by the juncture of spindle portions 36, 38. One face of the washer 42 is engaged by a plurality of ball bearings 44 held in circumferentially spaced relationship by a suitable cage 45. These ball bearings are received within an annular space formed in a ring 47 mounted on the spindle portion 38 for rotation therewith.
A coupler sleeve 48 includes a plurality of equally spaced inwardly extending keys 49, equal in number to the number of keyways 35. The coupler sleeve 48 includes a second set of keys 50 respectively received within the keyways 37.
The coupler sleeve 48 includes an annular recess receiving a snap ring 52. This snap ring abuts one end of bearing sleeve 53 which journals the coupler sleeve 48. The bearing sleeve includes an annular recess at its forward end receiving an annular flange 48a of the coupler sleeve. Thus, relative axial movement between the coupler sleeve 48 and the bearing sleeve 53 is prevented by reason of the snap ring 52 and the engagement of the flange 48a with the recess in the bearing sleeve.
The coupler sleeve includes an annular recess 55 receiving a portion of a coil spring 56. This spring engages the washer 42 and acts to urge the coupler sleeve inwardly or to the left as seen in FIG. 1.
A cam collar 58 includes an annular portion 59 rotatably engaged with the bearing sleeve 53. The collar portion 59 defines an annular shoulder 60 in coextensive engagement with an annular shoulder 61 defined by an annular flange 62 integral with the bearing sleeve 53. It is apparent that the spring 56 acts to hold the annular shoulders 60, 61 in engagement with each other. The flange 62 includes an annular surface 63 co-planar with an annular surface 48b on the coupler sleeve.
The cam collar 58 includes plural (three in the embodiment shown for purposes of illustration) equally spaced cam formations 64 as best seen in the developed view, FIG. 4. A cam collar 65 is fixedly secured to the annular surface b of the housing portion 100. This fixed cam collar 65 includes plural sets of cam formations, generally designated 66, and equal in number to the cam formations 64. Each cam formation 66 is defined by three stepped cams 67, 68 and 69. It will be apparent that as the cam collar 58 is rotated relative to the fixed cam collar 65, the cam formations 64 on the former will be selectively engaged, in seriatim, with the fixed cam formations 67, 68 and 69.
The three stepped cam formations will define three axial positions for the cam collar 58. When the cam formations 64 are engaged with the cam formations 69, continued rotation of the cam collar 58 (left to right as viewed in FIG. 4) will result in the formations 64 engaging the cam formations 67 thereby repositioning the cam collar 58 in its innermost position as seen in FIG. 1. It will be apparent that 120 of rotation of the cam collar will result in movement of the same axially through its three positions. One complete revolution of the cam collar will result in the same being successively and repeatedly moved to its various axial positions. Of course, the cam collar 58 could be axially positioned utilizing only one cam formation 64 and a single stepped cam formation 66; the provision of the plural sets of the cam formations 64, 66 is for the convenience of the operator in permitting him to make rapid and easy axial adjustments of the cam collar 58 with a minimum of rotation thereof. It should be added that the spring 56 will act to hold the cam formations 64 into engagement with a selected set of fixed cams 67, 68 or 69.
The hammer drill of the present invention is shown in the hammering only mode of operation in FIG. 1. When the tool motor is energized, rotation will be imparted to the shaft 16. However, such rotation will not be transferred to the spindle shaft 28 since the keys 49 on the coupler sleeve 48 are not received in the keyways of the spindle 28. When the operator places a suitable working tool, such as a drill bit (not shown), in engagement with the work and applies forward pressure to the tool, the spindle 28 and shaft 16 will move inwardly against the force of the spring 30 allowing the ratcheting teeth 21, 22 to come into engagement with each other thereby to provide a hammering action. Such hammering action will result since the ratchet formation 21 rotates with the shaft 16. Preferably, the ratcheting teeth 21, 22 are symmetrical in shape to provide the ratcheting or hammering function irrespective of the direction of rotation of the annular ratchet formation 19 relative to the fixed annular ratchet formation 23.
In the hammering only mode of operation as just described, it may be desirable to provide means to prevent rotation of the spindle 28 due to frictional drag from the bearing sleeve 32, the latter of course being engaged by the rotating shaft 16. To this end, the coupler sleeve 48 may be provided with an annular series of teeth or catch formations 70 which engage an annular series of fixed teeth or catch formations 71 formed on the forward annular surface of the housing portion 10a. These teeth or catch formations may be of any suitable shape and may be similar to the ratchet teeth 21, 22, for example. The catch formations prevent rotation of the coupler sleeve and the latter thereby prevents rotation of the spindle due to the interengagement of the keys 50 and keyways 37. In the hammering mode of operation as just described, the cam formations 64 on the cam collar 58 are in engagement with the fixed cam 67 thereby locating the cam collar in its innermost axial position as illustrated in FIG. 1.
If it is now desired to convert the hammer drill to provide a combined hammering and drilling function, the cam collar 58 is rotated and is cammed forwardly until the formations 64 are seated in abutting relation with the fixed cams 68. This will result in the cam collar being cammed forwardly to the position illustrated in FIG. 2. This forward axial movement of the cam collar 58 results in corresponding axial movement of the coupler sleeve 48 thereby positioning the keys 49 in the keyways 35. It will be apparent that the coupler sleeve 48 now couples the shaft 16 to the spindle 28 such that rotation of the former will cause rotation of the latter. Of course, the keys 50 on the coupler sleeve 48 are always received within the keyways 37 on the spindle portion 36. The spindle 28 and chuck 40 will now be rotated and simultaneous hammering may also be brought about in the same manner as described with respect to the hammering only mode of operation.
If the operator now desires rotation only, the cam collar 58 is again rotated to position the cam formations 64 with the fixed earns 69. This will cause the cam collar 58 to be cammed to its forwardmost position thereby imparting corresponding forward axial movement to the coupler sleeve 48. The annular surfaces 48b, 63 will now be located in closely spaced relationship with the washer 42. When the operator then urges the tool toward the work, the washer 42 will abut these annular surfaces thereby preventing further axial movement of the spindle 28 and sleeve 16 relative to the tool housing, in turn preventing the ratcheting teeth 21, 22 from coming into engagement with each other. Thus, rotation only will be imparted to the chuck 40.
1. In a power tool of the type adapted selectively to operate in a hammering mode, a drilling mode, and a combined hammering and drilling mode, which tool includes a first rotatably mounted member, a second member mounted for rotation with and relative to said first member, drive means connecting the motor of the tool to the second member tor rotating the latter, connection means on said first member for connecting the 5 latter to a working tool, hammering means including. first and second hammering elements, said first hammering element being connected with said drive means for rotating in unison with said second member and relative to said second hammering element, means for engaging and disengaging said first and second hammering elements in response to axial movement of said first and second members, and a thrust formation on said first member for movement in unison therewith, the improvement comprising:
a. a coupler sleeve slidable axially relative to said first and second members and connected to said first member for transmitting rotary movement thereto;
b. first and second coupling formations on said coupler sleeve and said second member, respectively, said coupling formations being interengaged in first and second axial positions of said coupler sleeve for rotation of the coupler sleeve in response to rotation of the second member and thereby defining said drilling mode and said combined hammering and drilling mode, respectively, said coupling formations being disengaged when said coupler sleeve occupies a third axial position thereby defining said hammering mode;
c. a fixed cam element;
d. a rotary cam element engaged with said first cam element for being cammed in a direction axially of said coupler sleeve in response to rotation of the rotary cam element; and
e, means connecting said rotary cam element with said coupler sleeve for rotation relative thereto and for axial movement in unison therewith whereby said rotary cam element serves to move said coupler sleeve to said first, second and third positions, said rotary cam element serving to locate said coupler sleeve in close adjacent relationship with said thrust formation when the former occupies said '6 first position thereby to prevent axial movement of said first and second members and the consequent engagement of said first and second hammering elements.
2. The improvement according to claim 1 wherein said rotary cam element is in the form of a collar having at least a portion thereof accessible exteriorly of the power tool for being manually rotated relative to said fixed cam element.
3. The improvement according to claim 2 wherein said fixed cam element and said collar have respective interengaged cam formations, one of said formations being stepped whereby said collar is cammed to three predetermined axial positions thereby establishing said three positions of said sleeve.
4. The improvement according to claim 3 wherein said'fixed cam element is annular in shape and wherein said fixed cam element and said collar have plural sets of said cam formations spaced circumferentially there- 'around whereby said collar may be successively and repeatedly located in its predetermined axial positions during a single revolution of said collar relative to said fixed cam element.
5. The improvement according to claim 1 further defined by:
a. first key and keyway means connecting said coupler sleeve to said first member; and
b. second key means defining one of said first and second coupler formations and second keyway means defining the other of said first and second coupler formations.
6. The improvement according to claim 1 further defined by:
a. a stationary member; and
b. first and second catch means on said stationary member and on said coupler sleeve, respectively, said first and second catch means being brought into engagement with each other when said coupler sleeve occupies said third axial position thereby to prevent rotation of said sleeve and said first rotary member in said hammering mode.