LI, Xiao (14-1-701 Fuxing Nanyuan, Shangcheng District Hangzhou, Zhejiang 8, 310008, CN)
WIKER, Juergen (152 Fulbright Lane, Schaumburg, Illinois, 60194, US)
CAI, Junxiao (Shenting Village, Zhoushan Yongkang, Zhejiang 6, 321316, CN)
LI, Xiao (14-1-701 Fuxing Nanyuan, Shangcheng District Hangzhou, Zhejiang 8, 310008, CN)
WIKER, Juergen (152 Fulbright Lane, Schaumburg, Illinois, 60194, US)
| CLAIMS: 1. A jigsaw, comprising: a housing (100); a motor (1) fixed in the housing (100); a driven shaft (6) rotatably mounted in the housing (100), the driven shaft (6) comprising an input end (6a) facing the motor (1), a supported end (6d) facing away from the motor (1) and an eccentric part (6b) between the input end (6a) and the supported end (6d); a transmission mechanism for transmitting the output rotation of the motor (1) to the input end (6a) of the driven shaft (6); an eccentric wheel (8) fixed to the supported end (6d); a driving plunger (10) coupled to the eccentric wheel (8) to be moved in a reciprocating direction by the eccentric wheel (8); a saw blade (20) attached to the driving plunger (10) so as to reciprocate with the driving plunger (10) in the reciprocating direction; and a pusher (7) driven to move by the eccentric part (6b) and pushing against the back of the saw blade (20) by means of a biasing rocker (21) to cause the saw blade (20) to oscillate in an oscillating direction lateral to the reciprocating direction. 2. The jigsaw of claim 1 , wherein the motor (1) is arranged in a handle portion (100a) of the housing (100) and has a central axis (xl ) substantially perpendicular to the reciprocating direction. 3. The jigsaw of claim 1 , wherein the transmission mechanism comprises a fixed ring gear (2), a pinion (4) fixed to an output shaft (l a) of the motor (1), at least two planet gears (3) engaged between the ring gear (2) and the pinion (4), and a planet carrier (30) which has at lease two input pins (30a) each inserted into a central hole of a corresponding planet gear (3) and an output portion (30b) coaxial with the output shaft (la) and coupled to or formed integrally with the input end (6a) of the driven shaft (6). 4. The jigsaw of each of claims 1 to 3, wherein the driven shaft (6) further comprises a middle supporting part (6c) that is supported by a supporting wall of the housing (100). 5. The jigsaw of each of claims 1 to 3, wherein the driving plunger (10) has a guided portion (10b) which is guided by a linear bushing (12) fixedly mounted in the housing (100). 6. The jigsaw of each of claims 1 to 3, wherein the driving plunger (10) extends generally in the reciprocating direction and has a U-shaped driven portion (10a) in which the eccentric wheel (8) is rotatably nested. 7. The jigsaw of claim 6, wherein the U-shaped driven portion (10a) has a longitudinal slot (lOd) through which the driven shaft (6) is inserted. 8. The jigsaw of each of claims 1 to 3, wherein the biasing rocker (21) is pivotably mounted to the housing (100) by means of a pivot pin (16), and has a recessed portion for receiving an outer end of the pusher (7); the pivot pin (16) is arranged between the saw blade (20) and the outer end of the pusher (7); a guiding roller (15) is rotatably mounted to the biasing rocker (21) at a location outward from the pivot pin (16) in the reciprocating direction; and the guiding roller (15) biases against the back of the saw blade (20). 9. The jigsaw of each of claims 1 to 3, wherein the pusher (7) is formed with a flange (7a) which is biased in a direction towards the eccentric part (6b) by a coil spring (34). 10. The jigsaw of each of claims 1 to 3, wherein the pusher (7) is guided to move parallel the reciprocating direction by a clamper bar (38) and the moving range of the pusher (7) is limited by the clamper bar (38). 11. The jigsaw of claim 10, wherein the clamper bar (38) is engaged by a cam shaft (40); and the cam shaft (40) is rotatable for adjusting the moving range of the pusher (7) and thus adjusting the cutting speed of the saw blade (20). 12. The jigsaw of each of claims 1 to 3, wherein the eccentric wheel (8) and the eccentric part (6b) each have a circular outer surface; the central axis of the eccentric wheel (8) is separated from the central axis (xl) of the motor (1) by a first eccentric distance (dl) which is large enough for achieving the reciprocating movement of the saw blade (20); and the central axis of the eccentric part (6b) is separated from the central axis (xl) of the motor (1) by a second eccentric distance (d2) which is small enough for achieving the oscillating movement of the saw blade (20). 13. The jigsaw of claim 12, wherein the central axes of the eccentric wheel (8) and the eccentric part (6b) are arranged at the same side of the central axis (xl) of the motor (1) or at opposite sides of the central axis (xl) of the motor (1). 14. The jigsaw of claim 13, wherein the reciprocating movement and the oscillating movement of the saw blade (20) have the same frequency. 15. The jigsaw of each of claims 1 to 3, wherein at least one of the eccentric wheel (8) and the eccentric part (6b) has a cam surface. 16. The jigsaw of claim 15, wherein the cam surface is designed such that the reciprocating movement and the oscillating movement of the saw blade (20) have different frequencies. |
Technical Field
The invention relates to a jigsaw. Background Art
A jigsaw or any other hand-held saw having an eccentrically-driven saw blade is well known. Such a jigsaw has a saw blade which is driven simultaneously in two directions, i.e., a reciprocating direction and an oscillating direction which is lateral to the reciprocating direction. In the reciprocating direction, the saw blade is driven to move reciprocately to cut a workpiece. In the oscillating direction, the saw blade is driven to oscillate forwardly to promote the saw blade to progress forwardly in the workpiece.
For achieving driving action in both of the two directions, two driving mechanisms are generally provided in a housing of the jigsaw. Hence, known jigsaws are generally bulky and heavy and thus are difficult to manufacture and use.
Summary of the Invention
In view of the problem existed in the prior art, an object of the invention is to provide a jigsaw which is compact and light weighted.
For this end, a jigsaw according to the invention comprises: a housing; a motor fixed in the housing; a driven shaft rotatably mounted in the housing, the driven shaft comprising an input end facing the motor, a supported end facing away from the motor and an eccentric part between the input end and the supported end; a transmission mechanism for transmitting the output rotation of the motor to the input end of the driven shaft; an eccentric wheel fixed to the supported end; a driving plunger coupled to the eccentric wheel to be reciprocately moved in a reciprocating direction by the eccentric wheel; a saw blade attached to the driving plunger so as to reciprocate with the driving plunger in the reciprocating direction; and a pusher driven to move by the eccentric part and pushing against the back of the saw blade by means of a biasing rocker to cause the saw blade to oscillate in an oscillating direction lateral to the reciprocating direction.
In accordance with a preferred embodiment of the invention, the motor is arranged in a handle portion of the housing and has a central axis substantially perpendicular to the reciprocating direction.
In accordance with another preferred embodiment of the invention, the transmission mechanism comprises a fixed ring gear, a pinion fixed to an output shaft of the motor, at least two planet gears engaged between the ring gear and the pinion, and a planet carrier which has at lease two input pins each inserted into a central hole of a corresponding planet gear and an output portion coaxial with the output shaft and coupled to or formed integrally with the input end of the driven shaft.
In accordance with another preferred embodiment of the invention, the driven shaft further comprises a middle supporting part that is supported by a supporting wall of the housing.
In accordance with another preferred embodiment of the invention, the driving plunger has a guided portion which is guided by a linear bushing fixedly mounted in the housing.
In accordance with another preferred embodiment of the invention, the driving plunger extends generally in the reciprocating direction and has a U-shaped driven portion in which the eccentric wheel is rotatably nested.
In accordance with another preferred embodiment of the invention, the U-shaped driven portion has a longitudinal slot through which the driven shaft is inserted.
In accordance with another preferred embodiment of the invention, the biasing rocker is pivotably mounted to the housing by means of a pivot pin, and has a recessed portion for receiving an outer end of the pusher; the pivot pin is arranged between the saw blade and the outer end of the pusher; a guiding roller is rotatably mounted to the biasing rocker at a location outward from the pivot pin in the reciprocating direction; and the guiding roller biases against the back of the saw blade.
In accordance with another preferred embodiment of the invention, the pusher is formed with a flange which is biased in a direction towards the eccentric part by a coil spring.
In accordance with another preferred embodiment of the invention, the pusher is guided to move parallel the reciprocating direction by a clamper bar and the moving range of the pusher is limited by the clamper bar.
In accordance with another preferred embodiment of the invention, the clamper bar is engaged by a cam shaft, and the cam shaft is rotatable for adjusting the moving range of the pusher and thus adjusting the cutting speed of the saw blade.
In accordance with another preferred embodiment of the invention, the eccentric wheel and the eccentric part each have a circular outer surface; the central axis of the eccentric wheel is separated from the central axis of the motor by a first eccentric distance which is large enough for achieving the reciprocating movement of the saw blade; and the central axis of the eccentric part is separated from the central axis of the motor by a second eccentric distance which is small enough for achieving the oscillating movement of the saw blade.
In accordance with another preferred embodiment of the invention, the central axes of the eccentric wheel and the eccentric part are arranged at the same side of the central axis of the motor or at opposite sides of the central axis of the motor.
In accordance with another preferred embodiment of the invention, the reciprocating movement and the oscillating movement of the saw blade have the same frequency.
In accordance with another preferred embodiment of the invention, at least one of the eccentric wheel and the eccentric part has a cam surface.
In accordance with another preferred embodiment of the invention, the cam surface is designed such that the reciprocating movement and the oscillating movement of the saw blade have different frequencies.
According to the invention, two eccentric type outputs are obtained from the driven shaft for driving the saw blade to reciprocate and oscillate simultaneously. Thus, the jigsaw is compact and light weighted and is easy to manufacture and use.
Brief Description of the Drawings
The invention will be further understood by reading the following detailed description with reference to the drawings in which:
Figure 1 is a schematic sectional view of a jigsaw according to a preferred embodiment of the invention;
Figure 2 is a schematic view of a motor of the jigsaw;
Figure 3 is a schematic view of a driven shaft of the jigsaw;
Figure 4 is a schematic sectional view of a transmission mechanism of the jigsaw;
Figure 5 is a schematic left side view of the transmission mechanism shown in Figure 4;
Figure 6 is a schematic sectional view showing a first eccentric type output of the jigsaw; and Figure 7 is a schematic sectional view showing a second eccentric type output of the jigsaw.
Detailed Description of Preferred Embodiments
With reference to Figures 1 to 7, a jigsaw according to a preferred embodiment of the invention is shown.
The jigsaw comprises a housing 100 for housing or mounting functional components of the saw.
The housing 100 has a motor receiving portion 100a, which preferably forms a handle portion of the saw as shown in Figure 1 , in which a motor 1 for providing driving power to a saw blade 20 is fixedly mounted. Alternatively, the portion 100a is only used for receiving the motor 1 and a separate handle (not shown) is attached to or formed integrally with the housing 100.
The motor 1 may be fixed within the housing 100 by means of screws, holding ribs, or form locking. The motor 1 may be powered by a rechargeable battery or by an outer power supply.
The housing 100 may be formed by a standard way, such as that typically used in DC appliances, for example, by plastic molding.
The housing 100 may be formed as a single piece. Preferably, for facilitating assembling, the housing 100 is formed as two housing parts which are assembled together after the functional components of the saw have been mounted to one of the housing parts.
The motor 1 has a rotational central axis xl which is lateral to, preferably perpendicular to, the extending or reciprocating direction of the saw blade 20.
The motor 1 drives a driven shaft 6 to rotate via a transmission mechanism. The transmission mechanism transmits an output rotational motion of the motor to a rotational movement of the driven shaft. Preferably, the rotation speed of the driven shaft is lower than the output rotation speed of the motor. In this condition, the transmission mechanism is a speed reduction mechanism. Preferably, the transmission mechanism is a gear mechanism, a screw mechanism, a belt mechanism, or any other mechanism known in the art that can transmit a rotational movement at a varied velocity.
In a particularly preferred embodiment, as shown in Figures 1 , 4 and 5, the transmission mechanism is a planet gear mechanism comprising: a ring gear 2 which is fixedly mounted within the housing, for example fixed at one end to an end wall of the motor 1 , the ring gear 2 having inner teeth and being coaxial with an output shaft l a (see Figure 2) of the motor 1 ; a pinion 4 fixed to the output shaft l a of the motor 1 so as to rotate with the output shaft l a; at least two planet gears 3 (three in the embodiment shown in Figure 5) disposed between the ring gear 2 and the pinion 4 and having teeth engaged with that of the ring gear 2 and the pinion 4; and a planet carrier 30 having at lease two input pins 30a (three in the embodiment shown in Figure 5) each of which is inserted into a central hole of a corresponding one of the planet gears 3 and an output portion 30b which is coaxial with output shaft l a of the motor 1 and is coupled to or formed integrally with an input end 6a (see Figure 3) of the driven shaft 6.
The pinion 4 is fixedly mounted to the output shaft l a of the motor 1 by any known way, for example by a key, splines, or form locking.
The planet gears 3 are each rotatable around one of the input pins 30a of the planet carrier 30. In other words, the planet gears 3 are rotatably carried by the input pins of the planet carrier 30 respectively.
In the embodiment shown in Figure 1 , the planet carrier 30 has an output portion 30b in the form of a hole to be fixed to the input end 6a of the driven shaft 6 in the form of a shaft end. Alternatively, the output portion 30b is in the form of a shaft end and the input end 6a is in the form of a hole. The shaft end and the hole are fixed to each other by a key, splines, or form locking.
In a variation, the output portion 30b of the planet carrier 30 is formed integrally with the input end 6a of the driven shaft 6. That is to say, the planet carrier 30 and the driven shaft form a single piece.
The driven shaft 6 is mounted to be coaxial with output shaft l a of the motor 1 , and is rotated when the motor 1 is activated. By way of example and as shown in Figure 3, the driven shaft 6 has a supported end 6d, which is opposite to the input end 6a, carried by a bushing 9 which is fixedly mounted within the housing 100 by means of a screw, ribs, form locking or any other anchoring means known in the art. Preferably, the driven shaft 6 further comprises a middle supporting part 6c. The middle supporting part 6c is rotatably carried by a bearing 5a mounted in a bearing plate 5. The bearing plate 5 is fixed to the housing 100 and/or to the ring gear 2, preferably to an end of the ring gear 2 opposite to that end of the ring gear 2 which is fixed to the end wall of the motor 1 as previously described.
In the embodiment shown in Figure 1 , the bearing plate 5 is inserted through a hole formed in a supporting wall of the housing 100 and thus is carried by the supporting wall. Meanwhile, the bearing plate 5 is fixed to the ring gear 2 by screws screwed into threaded holes 2a formed in the ring gear 2. Other known means may also be used for fixing the bearing plate 5 to the housing 100 and/or the ring gear 2.
By the transmission mechanism, the rotation of the output shaft l a of the motor 1 is transmitted to the driven shaft 6.
Figures 4 and 5 show an arrangement of the ring gear 2, the planet gears 3, the pinion 4 and the planet carrier 30.
The transmission ratio of the transmission mechanism can be derived from this arrangement: ω ΐ / ω6 = z2 / z4 + 1 where co l is the rotational speed of the output shaft l a of the motor 1 ; co6 is the rotational speed of the driven shaft 6; z2 is the number of teeth of the ring gear 2; and z4 is the number of teeth of the pinion 4.
It can be seen from the above equation that the rotational speed of the driven shaft 6 is always less than one half of the rotational speed of the output shaft l a of the motor 1.
By designing the diameters or the numbers of teeth of the ring gear 2, the planet gears 3 and the pinion 4, a desired transmission ratio of the transmission mechanism can be obtained.
Two eccentric type outputs are obtained from the driven shaft 6 for driving the saw blade 20 in two directions.
Specifically, as shown in Figure 6, an eccentric wheel 8, which is preferably circular, is fixedly mounted around the supported end 6d, or mounted on a further shaft section (not shown) of the driven shaft 6 provided between the supported end 6d and the middle supporting part 6c. The eccentric wheel 8 may directly contact the middle supporting part 6c as shown in Figure 6, or is separated from the middle supporting part 6c by means of a bushing (not shown). The central axis of the eccentric wheel 8 is separated from the rotational central axis x l of the motor by a first eccentric distance dl which corresponds to the reciprocating distance of the saw blade 20.
As also shown in Figure 6, an elongated driving plunger 10, which extends generally in the reciprocating direction of the saw blade 20, cooperates with the eccentric wheel 8 to drive the saw blade 20 in the reciprocating direction. Specifically, the driving plunger 10 comprises a U-shaped driven portion 10a, a guided portion 10b extending outwardly from the driven portion 10a, and a blade mounting end 10c extending outwardly from the guided portion 10b.
The eccentric wheel 8 is rotatably nested in the U-shaped driven portion 10a. The U-shaped driven portion 10a has a longitudinal slot l Od through which the driven shaft 6 passes. When the eccentric wheel 8 is rotated together with the driven shaft, the U-shaped driven portion 10a moves in the reciprocating direction along the driven shaft 6, and thus the whole driving plunger 10 moves in the in the reciprocating direction to drive the saw blade 20 to reciprocate.
The longitudinal slot l Od functions not only to allow the reciprocating movement of the driving plunger 10 but also to cooperate with the driving shaft 6 for preventing the U-shaped driven portion 10a from moving in a side direction perpendicular to both the reciprocating direction and the central axis xl of the motor.
The guided portion 10b is guided by a linear bushing 12 which is also fixedly mounted within the housing 100, preferably mounted to the same supporting wall of the housing 100 which supports the bearing plate 5 by means of a screw, ribs, form locking or any other anchoring means known in the art. The linear bushing 12 allows the guided portion 10b to move therein in the reciprocating direction, but restrict the guided portion 10b from moving in the side direction.
The blade mounting end 10c, on which the saw blade 20 is mounted by means of a blade clamper 32, extends preferably outside the housing 100 for facilitating the mounting and removing of the saw blade 20.
As described, by means of the eccentric wheel 8 and the driving plunger 10, a first eccentric type output is obtained from the driven shaft 6 for driving the saw blade 20 to reciprocate in the reciprocating direction.
As shown in Figure 7, a second eccentric type output is obtained from the driven shaft 6 by means of an eccentric part 6b which preferably has a circular cross section. The eccentric part 6b may be an integral portion of the driven shaft 6 formed between the input end 6a and the middle supporting part 6c or a separate part fixedly mounted to the driven shaft 6 between the input end 6a and the middle supporting part 6c. The central axis of the eccentric part 6b is separated from the central axis xl of the motor by a second eccentric distance d2 which is significantly smaller than the first eccentric distance dl so that the eccentric part 6b may provide an oscillation-like eccentric movement when the driven shaft 6 is rotated.
As also shown in Figure 7, a bar-like pusher 7 extending parallel to the reciprocating direction is driven by the eccentric part 6b. The pusher 7 comprises an inner end which abuts against the outer surface of the eccentric part 6b, a flange 7a formed or mounted on a middle portion of the pusher 7, and an outer end which push against a biasing rocker 21 which will be described later. A coil spring 34 is compressed between a side of the flange 7a which faces away from the driven shaft 6 and a supporting portion 36 formed by the housing 100 to push the flange 7a and thus the pusher 7 towards the eccentric part 6b. Preferably, the coil spring 34 is compressed between the flange 7a and the supporting portion 36 by means of spacers 1 1 at its upper and lower ends.
The pusher 7 is further supported by a U-shaped notch 2b formed in an edge of the ring gear 2 which faces away from the motor 1 , at the lower part of this edge.
As an optional feature, a clamper bar 38 clamps a portion of the pusher 7, near the flange 7a, to allow the pusher 7 moving parallel to the reciprocating direction but restrict the pusher 7 from moving in the side direction. The clamper bar 38 has a front end 38a abutting against another side the flange 7a which faces towards the driven shaft 6 and a back end 38b pivotable around a fixed pivot pin 39. The middle portion of the upper side of the clamper bar 38 is engaged by a cam shaft 40.
By means of the cam shaft 40, the pivot angle of the clamper bar 38 in one direction (clockwise direction in Figure 1) is limited. Thus, the moving range of the pusher 7 in two directions is determined by the eccentric part 6b of the driven shaft 6 and the cam shaft 40 respectively. Specifically, the outward movement of the pusher 7 (away from the driven shaft 6) is determined by the eccentric part 6b of the driven shaft 6, and the inward movement of the pusher 7 (towards the driven shaft 6) is determined by the cam shaft 40. The cam shaft 40 is rotatable around a fixed rotation axis 40a by a user from outside the housing 100 by means of a knob or lever and can be locked to any desired rotational position. In this way, the moving range of the pusher 7 is adjustable.
The biasing rocker 21 is pivotably mounted to the housing 100 by means of a pivot pin 16, and has a recessed portion for receiving the outer end of the pusher 7. The pivot pin 16 is arranged between the saw blade 20 and the outer end of the pusher 7, and a guiding roller 15 is rotatably mounted to the biasing rocker 21 at a location outward from the pivot pin 16 in the reciprocating direction. The guiding roller 15 pushes against the back of the saw blade 20.
In this way, within a turn of rotation of the driven shaft 6, the eccentric part 6b pushes the pusher 7 first outwardly and then inwardly parallel to the reciprocating direction, and the pusher 7 forces the biasing rocker 21 to pivot first in a clockwise direction and then in an anti-clockwise direction in figure 1 , and thus the guiding roller 15 moves against the back of the saw blade 20 forwardly and backwardly. That is to say, as the biasing rocker 21 swings around the pivot pin 16, an oscillating movement is transmitted to the saw blade 20 in an oscillating direction lateral to, preferably perpendicular to, the reciprocating direction. This oscillating movement promotes the saw blade to progress forwardly in the workpiece.
As mentioned above, the moving range of the pusher 7 is adjustable by means of the cam shaft 40. The swing angle of the biasing rocker 21 , and thus the forward cutting speed of the saw blade 20, is determined by the moving range of the pusher 7. Thus, by rotating the cam shaft 40, the cutting speed of the saw blade 20 is adjusted.
In the described embodiments, the eccentric wheel 8 and the eccentric part 6b may each have a circular outer surface. Thus, during each turn of rotation of the driven shaft 6, the saw blade 20 performs each of the reciprocating movement and the oscillating movement once. The central axes of the eccentric wheel 8 and the eccentric part 6b are preferably arranged at the same side of the central axis xl of the motor or at opposite sides of the central axis xl of the motor.
In a variation, the eccentric wheel 8 and/or the eccentric part 6b may have a cam surface which may be designed for optimizing the reciprocating movement and/or the oscillating movement.
When a cam surface for this purpose is used, the cam surface may be designed so that during each turn of rotation of the driven shaft 6, the eccentric wheel 8 and/or the eccentric part 6b having the cam surface outputs a reciprocating movement and/or an oscillating movement more than once. In this way, the frequencies of the reciprocating movement and the oscillating movement may be designed to be different from each other.
It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.