Abstract
The present invention relates to a dental handpiece (1) comprising: a dental handpiece (1) comprising: a head (4): a rotatable hollow shaft (15) which is rotatably arranged inside the head (4): a driving means for rotating the hollow shaft (15): a chuck (26) having resilient arms (27) for releasably clamping a dental drill (2), wherein the chuck (26) is fixed into the hollow shaft (15) so as to rotate with same: a ball (14) which is axially movably arranged inside the rotatable hollow shaft (15) and in direct contact with the resilient arms (27) of the chuck (26), wherein the ball (14) partly protrudes through an opening (17) on the upper end of the hollow shaft (15), and wherein the opening (17) is smaller than the size of the ball (14): a push button (7) which is arranged in the head (4) and configured to contact. when pressed by a user. the partly protruding ball (14) and move the ball (14) downwardly in between the resilient arms (27) so as flex the resilient arms (27) radially outwards and release the dental drill (2), wherein the resilient arms (27) bias the ball (14) inside the rotatable hollow shaft (15) towards the opening (17); and a biasing means to move the push button (7) away from the ball (14), wherein the push button (7) is not in contact with the ball (15) when it is released.
Claims
1. A dental handpiece comprising: a head; a rotatable hollow shaft which is rotatably arranged inside the head; a driving means for rotating the hollow shaft; a chuck having resilient arms for releasably clamping a dental drill, wherein the chuck is fixed into the hollow shaft so as to rotate with same; a ball which is axially movably arranged inside the rotatable hollow shaft and in direct contact with the resilient arms of the chuck, wherein the ball partly protrudes through an opening on the upper end of the hollow shaft, and wherein the opening is smaller than the size of the ball; a push button which is arranged in the head and configured to contact, when pressed by a user, the partly protruding ball and move the ball downwardly in between the resilient arms so as flex the resilient arms radially outwards and release the dental drill, wherein the resilient arms bias the ball inside the rotatable hollow shaft towards the opening; and a biasing means to move the push button away from the ball, wherein the push button is not in contact with the ball when it is released.
2. The dental handpiece according to claim 1, wherein the ball is made of ceramic material.
3. The dental handpiece according to claim 1, wherein the head includes a housing which accommodates a clamping means.
4. The dental handpiece according to claim 3, wherein the clamping means includes the chuck and the resilient arms.
5. The dental handpiece according to claim 1, wherein the driving means comprises a motor.
6. The dental handpiece according to claim 1, wherein the driving means is coupled to a driving shaft that is rotatably held through a bearing.
7. The dental handpiece according to claim 6, wherein the bearing includes an outer race, and inner race, multiple balls, and a retainer.
8. The dental handpiece according to claim 7, wherein an end of the driving shaft includes a crown gear.
9. The dental handpiece according to claim 8, wherein the crown gear meshes with a gear on the hollow shaft.
10. The dental handpiece according to claim 1, wherein the biasing means comprises a spring.
11. The dental handpiece according to claim 10, wherein the spring is a cone shaped spring.
12. A dental handpiece comprising: a head; a rotatable hollow shaft arranged inside the head; a driving means for rotating the hollow shaft; a chuck for releasably clamping a dental drill, wherein the chuck is fixed into the hollow shaft so as to rotate therewith; a ball which is axially movably arranged inside the rotatable hollow shaft, wherein the ball partly protrudes through an opening on the upper end of the hollow shaft; a push button which is arranged in the head and configured to contact, when pressed by a user, the partly protruding ball and move the ball downwardly so as to flex the chuck radially outwards and release the dental drill; and a biasing means to move the push button away from the ball, wherein the push button is not in contact with the ball when it is released.
13. The dental handpiece according to claim 12, wherein the chuck includes resilient arms.
14. The dental handpiece according to claim 13, wherein the ball is in direct contact with the resilient arms of the chuck.
15. The dental handpiece according to claim 12, wherein the opening on the upper end of the hollow shaft is smaller than the size of the ball.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] In the subsequent description, the present invention will be described in more detail by using exemplary embodiments and by referring to the drawings, wherein
[0014] FIG. 1is a schematic partial side view of a dental handpiece according to an embodiment of the invention;
[0015] FIG. 2ais a schematic partial vertical cross-sectional view of the head of the dental handpiece in FIG. 1, taken along the line I-I;
[0016] FIG. 2bis a schematic partial cross-sectional view of the head of the dental handpiece in FIG. 1, taken along the line I-I in the actuated state;
[0017] FIG. 2cis a schematic partial cross-sectional view of the head of a dental handpiece according to an alternative embodiment of the invention, taken along the line II-II in FIG. 1;
[0018] FIG. 3is a schematic partial cross-sectional view of the clamping mechanism inside the bearings of the dental handpiece in FIG. 1, taken along the line I-I;
[0019] FIG. 4ais a schematic partial cross-sectional view of the clamping mechanism of FIG. 3 without the bearings;
[0020] FIG. 4bis a schematic partial cross-sectional view of the clamping mechanism of FIG. 4a, in the actuated state;
[0021] FIG. 5ais a schematic perspective side view of the chuck of the dental handpiece in FIG. 1;
[0022] FIG. 5bis a schematic perspective view of the chuck of the dental handpiece in FIG. 1;
[0023] FIG. 6ais a schematic perspective view of the flange collar (hat-shaped) of the dental handpiece in FIG. 1;
[0024] FIG. 6bis a schematic perspective view of the outer and inner races of the dental handpiece in FIG. 1;
[0025] FIG. 6cis a schematic perspective view of the cap of the dental handpiece in FIG. 1;
[0026] FIG. 6dis a schematic perspective view of the screw ring of the dental handpiece in FIG. 1.
[0027] The reference numbers shown in the drawings denote the elements as listed below and will be referred to in the subsequent description of the exemplary embodiments. [0028] 1. Dental handpiece [0029] 2. Dental drill (burr) [0030] 3. Body [0031] 4. Head [0032] 5. Housing [0033] 5a. Gap [0034] 6. Internal Thread [0035] 7. Pushbutton [0036] 8. Cap [0037] 9. Flange collar (hat-shaped) [0038] 9a. Claw [0039] 9b. Air Gap (thermal insulation) [0040] 9 Cap [0041] 10 Contact surface (point like) [0042] 11. Spring (cone shaped) [0043] 12. Guide [0044] 13. Clamping means [0045] 14. Ball [0046] 15. Hollow shaft [0047] 16. Gear [0048] 17. Opening [0049] 18. Stop Edge [0050] 19. Bearing [0051] 20. Outer race [0052] 21. Inner race [0053] 22 Balls [0054] 23 Retainer [0055] 24. Screw ring [0056] 25 Nose [0057] 26. Chuck [0058] 27. Arm [0059] 27a. Contact point [0060] 28 Cut-out [0061] 29. Large diameter portion [0062] 30. Small diameter portion [0063] 31. Contact edge (Burr stop) [0064] 32. Driving shaft [0065] 33. Bearing [0066] 34. Outer race [0067] 35. Inner race [0068] 36. Balls [0069] 37. Retainer [0070] 38. Crown gear [0071] A: Axial Direction [0072] F: Actuation Force
[0073] FIG. 1 shows a dental handpiece (1) according to an embodiment of the invention. As shown in FIG. 1, dental handpiece (1) has a body (3) and a head (4). A dental drill (2) is detachably attached to the head (4). FIG. 2a shows an enlarged cross-sectional view of the head (4). As shown in FIG. 2a, the head (4) has a housing (5) which accommodates a clamping means (13). As shown in FIG. 4a the clamping means (13) has a chuck (26) with 35 resilient arms (27) for releasably clamping the dental drill (2). A hollow shaft (15) is rotatably arranged inside the head (4). The chuck (26) is fixed into the hollow shaft (15) to rotate with same. The dental handpiece (1) has a driving means such as a motor (not shown) for rotating the hollow shaft (15). The driving means is coupled to a driving shaft (32) as shown in FIG. 2a, that is rotatably held through a bearing (33) having an outer race (34), an inner race (35), multiple balls (36), and a retainer (37). The end of the driving shaft (32) has a crown gear (38) that meshes with a gear (16) on the hollow shaft (15). As shown in FIG. 3 the hollow shaft (15) is rotatably held through a couple of bearings (19) mounted into the housing (5). The bearing (19) has an outer race (20) and inner race (21), multiple balls (22) and a retainer (23).
[0074] As shown in FIG. 3, the clamping means (13) has a ball (14), preferably made of ceramic material, which is axially movably arranged inside the rotatable hollow shaft (15) and in direct contact with the resilient arms (27) of the chuck (26). The ball (14) partly protrudes through an opening (17) in the upper end of the hollow shaft (15). The resilient arms (27) are sufficiently long to bias the ball (14) towards into the opening (17). The size of the opening (17) is smaller than the size of the ball (14) so that it is retained partly within the hollow shaft (15). As shown in FIG. 3 the opening (17) has an annular stop edge (18) formed integrally with the upper end of the hollow shaft (15), which restricts the outwards movement of that ball (14). As shown in FIG. 2a and FIG. 2b the dental handpiece (1) has a push button (7) which is arranged in the head (4) and configured to contact, when pressed by a user, the partly protruding ball (14) and move the ball (14) downwardly in between the resilient arms (27) to flex the resilient arms (27) radially outwards and release the dental drill (2). Even when the push button (7) is entirely released, the ball (14) remains in direct contact with the upper portions of the two resilient arms (27). As shown in FIG. 5a the chuck (26) has two diametrically opposed cut-outs (28) in its upper portion to form the two resilient arms (27). As shown in FIG. 5b, a linear semi cylindrical channel is formed into the upper portion of the chuck (26) whose edges form two diametrically opposed contact points (27a) to directly contact the ball (14). As shown in FIG. 3, the chuck (26) has a large diameter portion (29) and a small diameter portion (30). When the resilient arms (27) are retracted the dental drill (2) can be manually inserted only until the upper end of the large diameter portion (29). When the resilient arms (27) are flexed, the dental drill (2) can be further inserted into the small diameter portion (30) until it abuts against the contact edge (31) (Burr stop). Once the push button (7) is released, the resilient arms (27) are retracted, and the dental drill (2) is clamped in the small diameter portion (30) between the resilient arms (27). The resilient arms (27) also bias the ball (14) inside the rotatable hollow shaft (15) towards the opening (17). As shown in FIG. 2a, the pushbutton (7) has a cap (8), and a hat-shaped flange collar (9) arranged inside the cap (8) and fixed thereto. The hat-shaped flange collar (9) has a point like contact surface (10), preferably planar, for directly contacting the ball (14). The pushbutton (7) has a biasing means such a spring (11), preferably a cone shaped spring (11) to move the push button (7) away and detach it from the ball (14). As shown in FIG. 2a, the point like contact surface (10) is not in contact with the ball (15) when the push button (7) is released. As shown in FIG. 2b, the contact surface (10) comes in point contact with the upper side of the ball (15) when the push button (7) is pressed downwards. The opening (17) of the shaft (15) and the gap between resilient arms (27) serve directly as a guide for the plunging ball (14). Thus, the ball (14) need not be fixed in a separate sleeve or bushing or the like for reciprocation inside the shaft (15).
[0075] FIG. 2c shows an alternative embodiment, wherein the cap (9) is provided as a single piece instead of two separate pieces. That means, the cap (8) and the hat-shaped Flange collar (9) of FIG. 2a can also be provided in the form of a single piece with a similar function. All other features remain the same. Thereby the number of pieces can be further reduced.
[0076] As shown in FIG. 2a, the housing (5) has an internal thread (6) which receives a screw ring (24). The screw ring (24) has a nose (25) which can be seen in FIG. 2c but not in FIG. 2a. The cross-sectional views respectively in FIG. 2a and FIG. 2c are rotated about 90 degrees with respect to each other. The cross-section in FIG. 2a is along the line I-I as shown in FIG. 1 and the cross section in FIG. 2c is along the line II-II as shown in FIG. 1. As shown in FIG. 2c, the nose (25) extends radially inwards and can abut from below against the claw (9a) of the hat-shaped flange collar (9) which extends radially outwards and prevents the push button (7) from disengaging from the housing (5). The hat-shaped flange collar (9) can be provided separately from or integrally with the cap (8;9). In the former case an air gap (9b) is preferably formed underneath the cap (8) to improve thermal insulation as shown in FIG. 2a. Alternatively the air gap (9b) may be filled with a material that is a poor heat-conductor.
[0077] As shown in FIG. 2a and FIG. 2c, the inner surface of the hat-shaped flange collar (9) slides on the outer surface of outer race (20) while being in contact with the latter which configures a guide (12) for the push button (7) movement. The nose (25) of the screw ring (24) is arranged above the claw (9a) of the hat-shaped flange collar (9). The hat-shaped flange collar (9) does not contact the inner radial surface of the screw ring (24). The housing (5) has a gap (5a) directly above the screw ring (24) and the nose (25), which allows the cap (8;9) to move upwards or downwards during the clamping/releasing operation. The outer cylindrical surface of the cap (8;9) does not contact the inner surface of the housing (5) during its entire movement thanks to a sufficient radial clearance. Thus, guide (12) serves as a guiding contact surface for the up/down movement of the cap (8;9). Through the above described configuration, the height and diameter of the head (4) can be further reduced.
