US3695365A

US3695365A - Torque and impulse transmitting machine

Info

Publication number: US3695365A
Application number: US87492A
Authority: US
Inventors: Fritz Schadlich
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1969-11-14
Filing date: 1970-11-06
Publication date: 1972-10-03
Anticipated expiration: 1989-10-03
Also published as: DE1957288A1; DE1957288B2; FR2069246A5; JPS5034787B1; GB1326956A

Abstract

A torque and impulse transmitting machine with a built-in motor wherein the tool supporting spindle receives impulses from a rotary impeller gear which drives the spindle in response to rotation of the output shaft of the motor and is biased against a flange of the spindle by a strong helical spring. The impeller gear is moved axially rearwardly and away from the spindle during each revolution of the spindle by a shifting device which has two cams or two crown gears. One of the cams or crown gears is axially movably mounted in the housing of the machine and the other cam or crown gear forms part of a hub on the impeller gear. The latter strikes against the flange of the spindle whenever it is free to follow the bias of the helical spring.

Description

United States Patent 1151 3,695,365 Schiidlich [451 Oct. 3, 1972 [54] TORQUE AND IMPULSE FOREIGN PATENTS OR APPLICATIONS RANSMITTING MACHINE 981,492 1/1965 Great Britain ..173/1 [72] Inventor: Fritz Schadlich, Stetten, Germany [73] Assignee: Robert Bosch GmbI-l, Stuttgart, Ger- Primary Exami"e"Meyer Peru many Assistant Examiner-Wesley S. Ratlifi, Jr. Filed: Nov. 1970 AttorneyMlchael S. Striker [21] Appl. No.: 87,492 [57] ABSTRACT o A torque and impulse transmitting machine with a [30] Forelgn Application Priority Data b ilmn motor wherein the tool supporting spindle 14, 1969 Germany; P '9 57 2884 receives impulses from a rotary impeller gear which drives the spindle in response to rotation of the output 52 US. Cl. ..173/109, 74/22, 173/115, shaft of the motor and is biased against a flange of the 173/ 1 19, 173/123 spindle by a strong helical spring. The impeller gear is [51] Int. Cl. ..B25d 9/00 moved axially rearwardly and away from the spindle [58] Field of Search ...74/22; l73/l15,109,119,123 during each revolution of the spindle by a shifting device which has two cams or two crown gears. One References Cited of the cams or crown gears is axially movably UNITED STATES PATENTS mounted in the housing of the machine and the other cam or crown gear forms part of a hub on the impeller Lochner gear The latter strikes against the flange of the pin- 3,433,082 3/1969 Bitter et a1 ..74/22 dle whenever it is f to f ll the bias f the helical 2,270,929 1 1942 Bugg ..74/22 Spring 2,775,898 1/1957 Baier ..74/22 2,968,960 l/1961 Fulop ..173/1 15 15 Claims, 2 Drawing Figures 30 32 V VI /l' PATENTED OUT 3 I972 SHEEI 1 OF 2 BACKGROUND OF THE lNVEN-TIQN The present invention relates to improvements in torque and impulse transmitting machines, particularly to improvements in portable power-operated torque and impulse transmitting machines. Still more particu larly, the invention relates to improvements in machines of the type wherein a rotary mass is coaxial with an axially reciprocable tool supporting spindle and is biased forwardly by a strong spring which can intermittently overcome the action of a shifting device serving to move the mass rearwardly and to thereupon permit the mass to strike against the revolving spindle and to impart to the spindle an axially oriented forward impulse.

Presently known torque and impulse transmitting machines can be divided into two distinct groups. The first group includes the just outlined machines wherein a rotary mass intermittently strikes against the revolving spindle. The second group includes machines of the type wherein a relatively weak spring biases apart two crown gears having axially extending teeth-One of the gears rotates with the spindle and the other gear is movable by the operator against the one gear whereby the one gear ratchets along the other gear and imparts to the revolving spindle a rapid sequence of impulses which drive a revolving tool into the material of the workpiece. A drawback of the second group of machines tool is that the force which is necessary to transmit to the spindle impulses must be furnished by the user. Also, the machines of the first group are quieter and less tiresome to the operator.

ln the machines of the first group, the mass which transmits impulses to the spindle normally assumes the form of a discrete flywheel or constitutes the rotor of the prime mover. A drawback of machines with discrete flywheels is that such parts contribute significantly to the weight and bulkiness of the machine. The machines wherein the mass constitutes the rotor of the prime mover exhibit the drawback that the revolving and axially movable rotor tends to breakor weaken the connections between the windings and the collector. Furthermore, the collector is subjected to excessive wear because it not only rotates but also moves back and forth with reference to the brushes.

SUMMARY OF THE INVENTION An object of the invention is to provide a torque and impulse transmitting machine which is subjected to less wear than the presently known machines which employ a rotary mass and which is more compact than conventional machines of the same capacity.

Another object of the invention is to provide the torque and impulse transmitting machine with novel impulse transmitting means which is capable of performing one or more additional functions.

A further object of the invention is to provide a torque and impulse transmitting machine which can be rapidly and conveniently adjusted to furnish impulses of desired magnitude. An additional object of the invention is to provide the machine with novel means for supporting, guiding and otherwise controlling movements of the spindle which drives the tool.

Still another object of the invention is to provide a torque and impulse transmitting machine which can be a rapidly converted into a power drill or vice versa.

The invention is embodied in a torque and impulse or impact transmitting machine, particularly in a portable machine with a built-in prime mover. The machine comprises housing means rotatably supporting the output member of the prime mover, a spindle rotatably and axially movably mounted in the housing means and having a preferably threaded tool-supporting front portion which can be connected with the adapter of a chuck or another suitable tool holding and retaining device, a preferably polygonal rear portion, and a preferably flange-like impact-receiving portion disposed between the front and rear portions, a heavy impeller gear axially movably mounted on the rear portion and serving to rotate the spindle in each of its axial positions, a transmission (preferably including a gear train and an intermediate shaft) for rotating the impeller gear in response to rotation of the output member, biasing means preferably comprising one or more strong helical springs for urging the impeller gear forwardly against the impact-receiving portion of the spindle, and shifting means including a first portion provided in the housing means and a second portion provided on the impeller gear. The two portions of the shifting means normally cooperate with each other in response to rotation of the impeller gear to shift the latter away from the impact-receiving portion at least once during each revolution of the spindle and to thereupon permit the impeller gear to strike against the impact-receiving portion under the action of the biasing means whereby the impleler gear propels the spindle forwardly.

The first portion of the shifting means may comprise an axially adjustable rotary cam whose axis is parallel to the axis of the spindle, and the second portion of the shifting means then comprises a face cam which is provided on a hub of the impeller gear. In accordance with another embodiment of the invention, each portion of the shifting means may comprise a crown gear having an annulus of alternating radially extending ribs or teeth and grooves or flutes. The crown gear which is provided on the impeller gear faces forwardly and the other crown gear is preferably adjustable in the housing means and is normally positioned in such a way that its teeth alternately enter the grooves and engage the teeth of the crown gear on the impeller gear to thereby enable the latter to perform a large number of axial movements and to strike against the spindle whenever the teeth of its crown gear enter the grooves of the other crown gear.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved machine itself, how ever, both as to its construction and its mode of operation, together with additional features nd advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary axial sectional view of a torque and impulse transmitting machine which embodies one form of the invention; and

FIG. 2 is a similar fragmentary axial sectional view of a second machine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The torque and impulse transmitting machine of FIG. 1 comprises a housing 2 for a prime mover, preferably an electric motor. The front wall 1 of the housing 2 is connected with a second housing or gear case 3 which comprises a substantially cylindrical shell 4. The front portion 5 of the shell 4 is of reduced diameter and serves as a sleeve for the spindle 29. The output shaft 6 of the motor in the housing 2 is connected with a pinion 7 which extends into the rear portion of the gear case 3. The shaft 6 is rotatable in an antifriction bearing 8 having grooved races for an annulus of rolling elements. The bearing 8 is installed in the front wall 1.

The gear case 3 further accommodates an intermediate shaft 9 whose rear end portion is mounted in a bearing (not shown) provided therefor in the wall 1. The front end portion 10 of the intermediate shaft is rotatable in a bore 10 of an externally threaded plugshaped adjusting member 11. The member 11 is of generally cylindrical shape and its external threads 12 mesh with threads provided in a tapped bore 13 of the gear case 3. The bore 13 is open at both ends and is parallel to the spindle 29. The adjusting member 11 is provided with a forwardly extending handgrip portion or knob 14 which is knurled or milled to facilitate rota- 'tion by hand so that the operator can move the adjusting member axially toward or away from the wall 1. The member 11 has a cylindrical rear end portion 15 of a slightly reduced diameter; this cylindrical portion 15 is surrounded by a rotary shifting cam 16 which is held against axial movement with reference to the adjusting member by a split ring 17. The cam 16 has a convex (spherical) rear surface.

A median portion of the intermediate shaft 9 is provided with an integral pinion 18 which is located behind the shifting cam 16 and meshes with a relatively large impeller gear 37 in the gear case 3. The rear portion of the intermediate shaft 9 is connected to or made integral with a gear 19 which meshes with the pinion 7 of the output shaft 6. The

parts

7, 19, 9, 18 constitute a transmission which rotates the impeller gear 37 in response to rotation of the output shaft 6.

The sleeve 5 of the shell 4 is provided with an axial bore 20 which is parallel to and located at a level above the tapped bore 13. The front portion of the bore 20 is enlarged, as at 21, to form a ring-shaped shoulder 22. The rear portion 23 of the bore 20 of reduced diameter and extends forwardly to a second ring-shaped shoulder 24. The median portion of the bore 20 contains a package of relatively hard dished springs 25 which are adjacent to the inner shoulder 24. The springs 25 are located immediately behind an axially movable ring-shaped rear bearing member 26 which surrounds the adjacent portion of the spindle 29 and is located directly behind a second package of relatively soft dished springs 27. The front portion 21 of the bore 20 contains a second ring-shaped bearing member 28 which surrounds and guides the adjacent portion of the spindle 29 and abuts against the front shoulder 22. The bearing member 28 is held against axial and angular movement with reference to the sleeve 5 by means which are not shown in the drawing.

The spindle 29 is of generally cylindrical shape and its externally threaded front portion 30 extends forwardly and beyond the sleeve 5 so that it can be readily connected to the adapter of a chuck or analogous tool retaining means. The spindle 29 is further provided with a circumferential groove 33 which is located between the threaded front portion 30 and the sleeve 5 and receives the tip of a radial screw 32 serving to connect the spindle with a ring 31. The space between the ring 31 and the front end face of the sleeve 5 accommodates one or more distancing rings or spacers 34 consisting of steel or other suitable metal. The combined thickness of the illustrated distancing rings 34 is such as to leave a clearance of about 1 millimeter for axial movements of the spindle 29.

A median portion of the spindle 29 is provided with a strong impact-receiving flange 35 which abuts against the springs 25 and is received with clearance in the rear portion 23 of the bore 20. The flange 35 is located immediately in front of the polygonal (preferably hexagonal) rear portion 36 of the spindle 29. The maximum transverse dimension of the rear portion 36 preferably equals or approximates the diameter of the main portion of the spindle 29.

The aforementioned impeller gear 37 is mounted on the rear portion 36 and is movable thereon axially of the spindle 29. As mentioned before, the impeller gear 37 meshes with the pinion 18 on the median portion of the intermediate shaft 9. The outline of the axial bore in the gear 37 matches that of the rear portion 36. The gear 37 is relatively large and reasonably heavy and has a forwardly projecting extension or hub 38. The rear part 39 of the hub 38 constitutes a face cam whose face abuts against the shifting cam 16 on the cylindrical portion 15 of the intermediate shaft 9. The front part 40 of the hub 38 is of reduced diameter and normally abuts against the impact-receiving flange 35.

The impeller gear 37 has a rearwardly projecting tubular extension which is surrounded by a steel washer 41 located in front of a ring-shaped retainer 42 for the front convolution of a strong helical spring 43. The rearrnost convolution of the spring 43 bears against the front race of a thrust bearing 44 which is mounted on a holder 45 abutting against the front wall 1 of the housing 2. The holder 45 surrounds the pinion 7 and a portion of the gear 19.

The cams 16, 39 constitute two portions of a shifting device which can move the impeller gear 37 rearwardly, at least once during each revolution of the spindle 29, against the action of the biasing means 43.

The operation:

When the motor in the housing 2 is started, the output shaft 6 rotates the intermediate shaft 9 by way of the pinion 7 and gear 19. The pinion 18 of the shaft 9 rotates the impeller gear '37 which rotates the polygonal rear portion 36 of the spindle 29 whereby the latter rotates the chuck, not shown. The configuration of the face on the cam 39 is such that the impeller gear 37 performs a reciprocatory axial movement provided that the cam 39 is held in engagement with the cam 16 on the intermediate shaft 9. Depending on the configuration of the cam 39, the impeller gear 37 can move back and forth once or more than once during each revolution of the spindle 29.

lnlrRA na-n If the adjusting member 11 extends into the gear case 3 to such an extent that the cam 16 engages with the face of the cam 39, the impeller gear 37 is caused to move axially of the polygonal end portion 36 but continues to drive the spindle 29. The spring 43 is inserted in prestressed condition and stores additional energy whenever the cams 16, 39 cause the gear 37 to move rearwardly, i.e., away from the impact-receiving flange 35 of the spindle 29. As shown, the axial length of the pinion 18 on the intermediate shaft 9 suffices to insure that the pinion remains in mesh with the impeller gear 37 in each axial position of this gear.

As the gear 37 rotates, a first portion of the face on the cam 39 causes it to move rearwardly and to stress the spring 43. A next-following portion of the face on the cam 39 then permits the gear 37 to move forwardly under the action of the spring 43 whereby the portion 40 of the hub 38 strikes against the flange 35 and imparts a sudden axial movement to the spindle 29 as well as to a tool held in the chuck which is secured to the front portion 30. Such chuck rotates with the spindle 29 and transmits torque to the tool. The strength of impulses which are transmitted to the flange 35 depends on the stress of the spring 43 and on configuration of the cam ,39, i.e., on the length of rearward strokes which the impeller gear 37 is caused to perform prior to being permitted to advance forwardly and to strike against the flange 35. By moving the adjusting member 11 axially inwardly, the operator can change the length of strokes of the impeller gear 37 and hence the mag nitude of impulses which are transmitted to the spindle 29. Such impulses cause more rapid penetration of the revolving tool into the material of a workpiece, for example, into a wall. That portion of each impulse which is not taken up by the workpiece is damped by the springs 25 which can shift the rear bearing member 26 axially forwardly so that the latter deforms the softer springs 27.

When the adjusting member 11 is moved to an axial position in which the cam 39 cannot bear against the convex rear surface of the cam 16 in any angular position of the impeller gear 37, the hub 38 simply abuts against the flange 35 and the machine of FIG. 1 can be operated as a simple power drill.

The gear .37 not only drives the spindle 29 but also transmits impulses to the flange 35. This brings about substantial savings in space.

The torque and impulse transmitting machine of FIG. 2 is in many respects similar to the machine of FIG. 1. The main difference between the two machines is that the shifting cam 16 of FIG. 1 is replaced with a crown gear 49 having a rear end face provided with an annulus of radially extending flutes or grooves altemating with ribs or teeth 50. The crown gear 49 is nonrotatably mounted in the gear case 3' and is coaxial with the spindle 29. The crown gear 49 is movable axially of the spindle 29 and can be arrested in a selected axial position by a clamping screw 51. The hub 52 of the impeller gear 53 which replaces the gear 37 of FIG. 1 has a front face provided with an annulus of radially extending flutes alternating with ribs or teeth 54 which constitute a second crown gear. The teeth 54 can mate with and ratchet over the teeth 50 of the crown gear 49. When the crown gear 49 is moved into requisite axial position, the hub 52 can strike against the flange 35 of the spindle 29 whenever the teeth 54 can enter the flutes between the teeth 50 and is moved away from the flange 35 to stress the spring 43 whenever the top lands of the teeth 54 ride over the top lands of the teeth 50. When the crown gear 49 is moved so far away from the teeth 54 that the teeth 54 are constantly out of mesh with the teeth 50 and the hub 52 bears continuously against the flange 35 of the spindle 29, the machine of FIG. 2 can be used as a simple portable power drill. An advantage of the machine of FIG. 2 is that the spindle 29 can receive a large number of impulses during each revolution of the gear 53.

The front end portion of the intermediate shaft 9 whose pinion 18 mates with the gear 53 is mounted in a radial antifriction bearing 55.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A torque and impulse transmitting machine, comprising housing means; a prime mover having an output member rotatably mounted in said housing means; a spindle rotatably and axially movably mounted in said housing means and having a tool-supporting front por tion, a rear portion and an impact-receiving portion between said front and rear portions; an impeller gear axially movably mounted on said rear portion and arranged to rotate with said spindle; transmission means for rotating said gear in response to rotation of said output member; biasing means for urging said gear forwardly against said impact-receiving portion; and shifting means including a first portion provided in said housing means and a second portion provided on said gear and cooperating with said first portion in response to rotation of said gear to shift the latter away from said impact-receiving portion at least once during each revolution of said spindle and to thereupon permit the gear to strike against said impact-receiving portion under the action of said biasing means and to thereby propel the spindle forwardly.

2. A combination as defined in claim 1, wherein said impact-receiving portion is a flange and said impeller gear comprises a hub which strikes against said flange.

3. A combination as defined in claim 1, wherein said prime mover is a motor which is built into said housing means and further comprising second biasing means for urging said spindle axially rearwardly.

4. A combination as defi'ned in claim 1, wherein said impeller gear comprises a hub which strikes against said impact-receiving portion, and said second portion of said shifting means is a face cam provided on said hub.

5. A combination as defined in claim 4, wherein said first portion of said shifting means comprises a second cam having a annular convex surface engaging with said face cam while said gear is being shifted away from said impact-receiving portion.

6. A combination as defined in claim 4, wherein said first portion of said shifting means comprises a second cam and said shifting means further comprises an adjusting member rotatably supporting said second cam and being movable in said housing means in parallelism with the axis of said spindle.

7. A combination as defined in claim 6, wherein said adjusting member is movable to a position in which said second cam is disengaged from said first cam in each angular position of said gear. 7

8. A combination as defined in claim 1, wherein said second portion of said shifting means comprises an annulus of alternating substantially radially extending ribs and grooves provided on and coaxial with said gear, said first portion of said shifting means comprising a second annulus of alternating substantially radially extending ribs and grooves mounted in said housing means and facing said first annulus.

9. A combination as defined in claim 8, wherein said second annulus is adjustable in said housing means axially of said spindle.

H). A combination as defined in claim 9, wherein said second annulus is movable axially to a position in which its ribs are disengaged from the ribs of said first annulus in each angular position of said gear.

1 l. A combination as defined in claim 1, wherein said housing means comprises a portion located behind said gear and said biasing means reacts against said portion of said housing means.

12. A combination as defined in claim 11, further comprising a holder interposed between said portion of said housing means and said biasing means and a thrust bearing disposed between said holder and said biasing means so that said biasing means can rotate with said gear relative to said holder.

13. A combination as defined in claim 12, wherein said biasing means comprises a strong helical spring which is coaxial with said gear.

14. A combination as defined in claim 1, wherein said housing means comprises a sleeve-like front portion surrounding said spindle and further comprising at least two ring-shaped bearing members in said sleevelike front portion and axially movably supporting said spindle, at least one of said bearing members being mounted in said sleeve-like front portion against axial movement with reference to said housing means.

15. A combination as defined in claim 14, wherein said one bearing member is located in front of the other bearing member and said other bearing member is movable axially of said sleeve-like front portion, and further comprising spring means adjacent to at least one axial end of said other bearing member whereby said spring means absorbs the shocks applied by said impact-receiving portion when the tool supported by the front portion of said spindle does not penetrate into a workpiece while said gear rotates and transmits impulses to the spindle.

Claims

1. A torque and impulse transmitting machine, comprising housing means; a prime mover having an output member rotatably mounted in said housing means; a spindle rotatably and axially movably mounted in said housing means and having a tool-supporting front portion, a rear portion and an impact-receiving portion between said front and rear portions; an impeller gear axially movably mounted on said rear portion and arranged to rotate with said spindle; transmission means for rotating said gear in response to rotation of said output member; biasing means for urging said gear forwardly against said impact-receiving portion; and shifting means including a first portion provided in said housing means and a second portion provided on said gear and cooperating with said first portion in response to rotation of said gear to shift the latter away from said impact-receiving portion at least once during each revolution of said spindle and to thereupon permit the gear to strike against said impact-receiving portion under the action of said biasing means and to thereby propel the spindle forwardly.

4. A combination as defined in claim 1, wherein said impeller gear comprises a hub which strikes against said impact-receiving portion, and said second portion of said shifting means is a face cam provided on said hub.

7. A combination as defined in claim 6, wherein said adjusting member is movable to a position in which said second cam is disengaged from said first cam in each angular position of said gear.

10. A combination as defined in claim 9, wherein said second annulus is movable axially to a position in which its ribs are disengaged from the ribs of said first annulus in each angular position of said gear.

11. A combination as defined in claim 1, wherein said housing means comprises a portion located behind said gear and said biasing means reacts against said portion of said housing means.

14. A combination as defined in claim 1, wherein said housing means comprises a sleeve-like front portion surrounding said spindle and further comprising at least two ring-shaped bearing members in said sleeve-like front portion and axially movably supporting said spindle, at least one of said bearing members being mounted in said sleeve-like front portion against axial movement with reference to said housing means.