Electric chain saw

Abstract

 The present invention discloses an electric chain saw, which includes a casing (1) as well as a motor and the brake device thereof installed in the casing. The brake device includes the following parts: A brake drum (4) sleeved on and revolving together with a motor shaft; and a brake strap (5) sleeved on outer edge of the brake drum (4), with one end connected with a first brake unit and the other end with a second brake unit. The brake device in the present invention adopts two brake units, and can deal with a normal braking condition and an emergency braking condition, respectively. When one of the brake units fails, the electric chain saw of the present invention can be braked via the other brake unit, fully satisfying requirements on operation safety of the electric chain saw, characteristic of quick brake, simple operation, and sensitive action. Besides, compared to the prior art electric chain saw adopting such a brake mechanism as a clutch, a lever and a gear, the present invention is simple in the overall structure and less in the part quantity, more advantageous in miniaturization design of the electric chain saw.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to an electric chain saw.

BACKGROUND OF THE INVENTION

[0002] During an electric chain saw is used, its chain saw blade may kick back towards an operator due to an accidental collision, endangering the operator. Therefore, the electric chain saw is generally provided inside with a brake device. However, there is commonly only one brake unit in the brake device in the commercially available electric chain saw. Once this brake unit fails or is damaged, the operator cannot brake it again. Thus, it still fails to improve operation safety of the electric chain saw. Besides, the brake device of the prior art electric chain saw brakes a motor commonly via such mechanisms as a clutch, a lever and a gear that are connected with a motor shaft, which is not only slow in braking but also complicated in structure with many parts, disadvantageous for miniaturizing the electric chain saw.

[0003] On the other hand, during the prior art electric chain saw is normally powered off, since its chain saw blade cannot be stopped immediately with inertia, it is still possible to endanger the operator. In order to reduce the danger and ensure the operator's safety, a brake device has to be designed in the electric chain saw that can brake during a normal shutdown. However, the brake device in the prior art electric chain saw only has an emergency braking function, that is, it brakes the motor shaft after forced interruption of the power supply circuit of the motor, and is incapable of braking the motor shaft when the electric chain saw is normally shut down.

CONTENTS OF THE INVENTION

[0004] A purpose of the present invention is to provide an electric chain saw, in which is stalled a brake device that not only is simple in structure and quick in braking but also has two brake units, greatly improving operation safety of the electric chain saw.

[0005] A technical solution of the present invention is to provide an electric chain saw, which includes a casing as well as a motor and the brake device thereof installed in the casing. The brake device includes the following parts:

A brake drum sleeved on and revolving together with a motor shaft; and a brake strap sleeved on outer edge of the brake drum, with one end connected with a first brake unit and the other end with a second brake unit.

[0006] The casing of the present invention is provided inside with a main power switch serially connected with the motor. The first brake unit includes a first coupling, a first elastic member, a button and a driving member. The first coupling is fixed on the brake strap. The button and the driving member are connected with the casing via a pivot, respectively. The button, opposite at one end to a contact on the main power switch, is provided at the other end with a molded main tooth section. The driving member, opposite at one end to one end of the first coupling, is provided at the other end with a molded secondary tooth section engaged with the main tooth section. The first elastic member, located between the other end of the first coupling and the casing, provides an elastic force that drives the first coupling to move towards one side to tighten the brake strap.

[0007] The casing in the present invention is further provided inside with a first passage that guides the first coupling to perform rectilinear motion.

[0008] The first elastic member in the present invention is further a spring, through which goes one end of the brake strap before being fixed on the first coupling via a first fixing pin. The first passage has an end wall on both sides. The spring is propped at one end against the first coupling and at the other end against the end wall on one side of the first passage.

[0009] The first coupling in the present invention is provided at one end with a shrinkage pool into which the spring can be propped and at the other end with a molded convex section. This convex section, extending out of a pilot hole on the end wall on the other side of the first passage, is opposite to an extension handle molded on the driving member.

[0010] The casing of the present invention is provided inside with a protection power switch serially connected with the motor. The second brake unit includes a second coupling, a second elastic member, a connecting rod, a protection plate and a trigger knob. The second coupling is fixed on the brake strap. The protection plate is connected with the casing via the pivot, with one end exposed outside the casing and the other end pin-connected with one end of the connecting rod. The connecting rod is pin-connected at the other end with one end of the second coupling. The second elastic member, propped between the other end of the second coupling and the casing, provides an elastic force that drives the second coupling to move towards one side to tighten the brake strap. The trigger knob is connected with the casing via the pivot, with one end opposite to a contact on the protection power switch and the other end controlled by a bulge molded on the protection plate.

[0011] The casing in the present invention is further provided inside with a second passage that guides the second coupling to perform rectilinear motion.

[0012] The second elastic member in the present invention is further also a spring, through which goes one end of the brake strap before being fixed on the second coupling via a second fixing pin. The second passage has an end wall on both sides. The spring is propped at one end against the second coupling and at the other end against the end wall on one side of the second passage.

[0013] The second coupling in the present invention is provided at one end with a shrinkage pool into which the spring can be propped and at the other end with a molded pin-connected handle. The pin-connected handle, extending out of a pilot hole on the end wall on the other side of the second passage, is pin-connected with the connecting rod.

[0014] The first brake unit in the present invention is fitted and linked with the main power switch, realizing the normal braking function of the electric chain saw. The specific action principle is as below.

[0015] When an operator normally powers on the electric chain saw to use it, he/she presses the contact on the main power switch through pressing the button, thus turning on the main power switch. Meanwhile, the driving member revolves under the action of the button, then pushes against the first coupling towards one side by overcoming the elastic force of the first elastic member, and forces the brake strap to loosen and separate from the brake drum, thus enabling the motor shaft to drive the chain saw blade to revolve normally. Besides, during using the electric chain saw, the operator needs to persistently press the button, so as to keep the main power switch on and meanwhile provide a persistent force to prevent the first elastic member from being elastically reset.

[0016] When the operator needs to brake normally, he/she only needs to release the button. Thereby the main power switch will be turned off immediately, and the power supply circuit of the motor cut off. Meanwhile, the driving member revolves under the action of the button, and the force pushing against one end of the first coupling is removed. The first elastic member, immediately elastically reset because of no resistance, pushes the first coupling to move towards one side to tighten the brake strap. This makes the brake strap lock the brake drum, preventing the motor shaft from keeping on driving the chain saw blade to revolve, realizing the purpose of braking.

[0017] Meanwhile, The second brake unit in the present invention is fitted and linked with the protection switch, realizing the emergency braking function of the electric chain saw. The specific action principle is as below.

[0018] When the operator uses the electric chain saw normally, the protection plate has to be pulled to an initial position. During this pulling process, the protection plate pushes via the bulge on it against the trigger knob, which then presses the contact on the protection power switch, making the protection power switch turned on. Meanwhile, the protection plate pushes against the second coupling with the help of the connecting rod to overcome the elastic force of the second elastic member, and forces the brake strap to loosen and separate from the brake drum, thus enabling the motor shaft to drive the chain saw blade to revolve normally. Besides, the protection plate has to be always kept at the initial position, so as to keep the protection power switch on and meanwhile provide a persistent force to prevent the second elastic member from being elastically reset.

[0019] When the operator needs to brake emergently, he/she only needs to revolve the protection plate towards outside of the casing, and stop the bulge on the protection plate from pushing against the trigger knob. In this way, the trigger knob cannot press the contact on the protection power switch anymore, thus turning off the protection power switch and cutting off the power supply circuit of the motor. Meanwhile, with the help of the connecting rod, the protection plate pulls the second coupling to move towards one side in the revolving process to tighten the brake strap. This makes the brake strap lock the brake drum, preventing the motor shaft from keeping on driving the chain saw blade to revolve, finally realizing the purpose of braking.

[0020] Another purpose of the present invention is to provide an electric chain saw that can be braked normally, in which the brake device brakes the motor shaft via the first brake unit fitted and linked with the main power switch, so as to realize the purpose of braking the electric chain saw under the condition that the electric chain saw is normally powered off, thus filling up a gap that the prior art electric chain saw cannot be braked normally and further ensuring the operator's safety. The special technical solution of this electric chain saw is as below.

[0021] An electric chain saw is provided that can be braked normally, including a casing and a brake device therein. The casing includes a bare casing and a rear handle integrated with the bare casing. The bare casing is provided inside with a motor. The rear handle is provided inside with a main power switch serially connected with the motor. The brake device includes the following parts:

A brake drum sleeved on and revolving together with a motor shaft; and

a brake strap sleeved on outer edge of the brake drum, with one end connected with a first brake unit.

[0022] The first brake unit includes the following parts:

A button pivotally connected with the rear handle, with one end corresponding to the main power switch and the other end provided with a molded main tooth section;

a driving member pivotally connected with the bare casing, with one end provided with a secondary tooth section fitted with the main tooth section and the other end with an extension handle; and

a first coupling movably installed in the bare casing, connected with one end of the brake strap, and propped against an extension handle of the driving member.

[0023] The above-mentioned electric chain saw that can be braked normally further includes a first elastic member. The first coupling is provided at one end with a first shrinkage pool into which the first elastic member can be propped and at the other end with a molded convex section.

[0024] The present invention has the following advantages:

1. The electric chain saw of the present invention, provided with the two brake units in the brake device, can deal with a normal braking condition and an emergency braking condition, respectively. Besides, when one of the brake units fails, the electric chain saw of the present invention can be braked via the other brake unit, thus greatly improving operation safety of the electric chain saw.

2. In the electric chain saw of the present invention, the two brake units in the brake device brake the motor all via the same brake strap and brake drum, and meanwhile they are linked with the main power switch and the protection switch of the electric chain saw, respectively, truly attaining the purpose of braking immediately after being powered off, characteristic of quick brake, simple operation, and sensitive action. Besides, compared to the prior art electric chain saw adopting such a brake mechanism as a clutch, a lever and a gear, the present invention is simple in the overall structure and less in the part quantity, more advantageous in miniaturization design of the electric chain saw.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will further be described below with reference to drawings and embodiments.

Figure 1 is a structural schematic view of an embodiment of the electric chain saw of the present invention.

Figure 2 is a separate stereoscopic structural schematic view of the button in Figure 1.

Figure 3 is a separate stereoscopic structural schematic view of the driving member in Figure 1.

Figure 4 is a separate stereoscopic structural schematic view of the first coupling in Figure 1.

Figure 5 is a side view of the first coupling.

Figure 6 is a sectional view along line A-A in Figure 5.

Figure 7 is a separate stereoscopic structural schematic view of the protection plate in Figure 1.

Figure 8 is a front view of the protection plate.

Figure 9 is a right view of Figure 8.

Figure 10 is a separate stereoscopic structural schematic view of the second coupling in Figure 1.

Figure 11 is a front view of the second coupling.

Figure 12 is a left view of Figure 11.

Figure 13 is a sectional view along line B-B in Figure 12.

Figure 14 is an assembly schematic drawing of the first coupling, the first elastic member, the second coupling, and the second elastic member on the brake strap.

Figure 15 is a stereoscopic structural schematic view of Figure 14 after assembly.

Figure 16 is a structural schematic view of the electric chain saw in Figure 1 in a normal braking state.

Figure 17 is a structural schematic view of the electric chain saw in Figure 1 in an emergency braking state.

[0026] In the drawings: 1. Casing; 101. bare casing; 102. front handle; 103. rear handle; 2. main power switch; 3. protection power switch; 4. brake drum; 5. brake strap; 6. first coupling; 601. first shrinkage pool; 602. convex section;7. first elastic member; 8. button; 801. main tooth section; 9. driving member; 901. secondary tooth section; 902. extension handle; 10. first passage; 11. second coupling; 111. second shrinkage pool; 112. pin-connected handle; 12. second elastic member; 13. connecting rod; 14. protection plate; 141. bulge; 15. trigger knob; 16. second passage; 17. first fixing pin; 18. second fixing pin; 19. pivot; 20. pivot; 21. pivot; and 22. pivot.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] Embodiment: The technical solution of the present invention will further be described below with reference to embodiments and drawings.

[0028] An embodiment of the electric chain saw of the present invention, as shown in Figure 1, includes a casing 1, a motor installed in the casing 1, a chain saw blade (not shown in the drawing) driven by a motor shaft, and a brake device installed in the casing 1. The casing 1 is composed of a bare casing 101 as well as a front handle 102 and a rear handle 103 integrated with the bare casing 101. The rear handle 103 is provided inside with a main power switch 2, and the bare casing 101 with a motor and a protection power switches 3, with the motor, the main power switch 2 and the protection power switch 3 serially connected with each other. The brake device is composed of a brake drum 4, a brake strap 5, a first brake unit and a second brake unit. The brake drum 4 is sleeved on and revolves together with a motor shaft. The brake strap 5 is sleeved on outer edge of the brake drum 4, with one end connected with a first brake unit that is fitted with the main power switch 2. The brake strap 5 is connected at the other end with the second brake unit, which is fitted with the protection power switch 3.

[0029] The first brake unit in this embodiment includes a first coupling 6, a first elastic member 7, a button 8 and a driving member 9. As shown in Figures 1 to 3, the button 8 is connected via a pivot 19 with the rear handle 103, and the driving member 9 via a pivot 20 with the bare casing 101. The button 8, opposite at one end to a contact on the main power switch 2, is provided at the other end with a molded main tooth section 801. The driving member 9, with a molded extension handle 902 at one end, is provided at the other end with a molded secondary tooth section 901 engaged with the main tooth section 801.

[0030] Again as shown in Figures 1, 4, 5, 6, 14 and 15, the first coupling 6 in this embodiment is provided at one end with a first shrinkage pool 601, and at the other end with a molded convex section 602. The first elastic member 7 is a spring, through which goes one end of the brake strap 5 before being fixed on the first coupling 6 via a first fixing pin 17. Besides, the bare casing 101 in this embodiment is provided inside with a first passage 10 that guides the first coupling 6 to perform rectilinear motion. The first passage 10 has an end wall on both sides. The spring is propped at one end into the first shrinkage pool 601 on the first coupling 6, and at the other end against the end wall on one side of the first passage 10, thus providing an elastic force that drives the first coupling 6 to move towards one side to tighten the brake strap 5. The convex section 602 on the first coupling 6 can extend out of a pilot hole on the end wall of the other side of the first passage 10, thus opposite to an extension handle 902 molded on the driving member 9.

[0031] The second brake unit in this embodiment includes a second coupling 11, a second elastic member 12, a connecting rod 13, a protection plate 14 and a trigger knob 15. As shown in Figures 1, 7, 8, and 9, the protection plate 14 in this embodiment is connected via a pivot 22 with the bare casing 101, with one end exposed outside the bare casing 101 and located in front of the front handle 102 and the other end pin-connected with one end of the connecting rod 13. Meanwhile, the trigger knob 15 is connected with the bare casing 101 via a pivot 21, with one end opposite to a contact on the protection power switch 3 and the other end controlled by a bulge 141 molded on the protection plate 14.

[0032] Again as shown in Figures 1, 10, 11, 12, 13, 14 and 15, the second coupling 11 in this embodiment is provided at one end with a second shrinkage pool 111 and at the other end with a molded pin-connected handle 112. The second elastic member 12 in this embodiment is also a spring, through which goes the other end of the brake strap 5 before being fixed on the second coupling 11 via a second fixing pin 18.

[0033] Besides, the bare casing 101 in this embodiment is provided inside with a second passage 16 that guides the second coupling 11 to perform rectilinear motion. The second passage 16 has an end wall on both sides. The spring is propped at one end into the second shrinkage pool 111 on the second coupling 11, and at the other end against the end wall on one side of the second passage 16, thus providing an elastic force that drives the second coupling 11 to move towards one side to tighten the brake strap 5. The pin-connected handle 112 on the second coupling 11, extending out of a pilot hole on the end wall of the other side of the second passage 16, is pin-connected with the other end of the above-mentioned connecting rod 13.

[0034] The first brake unit in this embodiment is fitted and linked with the main power switch 2, realizing the normal braking function of the electric chain saw. As shown in Figures 1 and 16, the specific principle is described as below.

[0035] When an operator normally powers on the electric chain saw to use it, he/she presses the contact on the main power switch 2 through pressing the button 8, thus turning on the main power switch 2. The button 8, after revolving round the pivot 19, drives the driving member 9 to revolve through coordination between the main tooth section 801 on the button 8 and the secondary tooth section 901 on the driving member 9. After the driving member 9 revolves, the extension handle 902 on the driving member 9 overcomes an elastic force of the first elastic member 7 and pushes against the first coupling 6 towards one side, forcing the brake strap 5 to loosen and separate from the brake drum 4, thus enabling the motor shaft to drive the chain saw blade to revolve normally. Besides, during using the electric chain saw, the operator needs to persistently press the button 8, so as to provide a persistent force to prevent the first elastic member 7 from being elastically reset and keep the main power switch 2 on, as shown in Figure 1.

[0036] When the operator needs to brake normally, he/she only needs to release the button 8. In this way, the main power switch 2 will be turned off immediately, and the power supply circuit of the motor cut off. Meanwhile, the driving member 9 revolves under the action of the button 8, and the force pushing against one end of the first coupling 6 is removed. The first elastic member 7, immediately elastically reset because of no resistance, pushes the first coupling 6 to move towards one side to tighten the brake strap 5. This makes the brake strap 5 lock the brake drum 4, preventing the motor shaft from keeping on driving the chain saw blade to revolve, realizing the purpose of braking, as shown in Figure 16.

[0037] Meanwhile, the second brake unit in this embodiment is fitted and linked with the protection power switch 3, realizing the emergency braking function of the electric chain saw. As shown in Figures 1 and 17, the specific principle is described as below.

[0038] When the operator uses the electric chain saw normally, the protection plate 14 has to be pulled to an initial position. During this pulling process, the protection plate 14 pushes via the bulge 141 on it against the trigger knob 15, which then presses the contact on the protection power switch 3, making the protection power switch 3 turned on. Meanwhile, the protection plate 14 pushes against the second coupling 11 with the help of the connecting rod 13 to overcome the elastic force of the second elastic member 12, and forces the brake strap 5 to loosen and separate from the brake drum 4, thus enabling the motor shaft to drive the chain saw blade to revolve normally. Besides, the protection plate 14 has to be always kept at the initial position, so as to keep the protection power switch 3 on and meanwhile provide a persistent force to prevent the second elastic member 12 from being elastically reset, as shown in Figure 1.

[0039] When the operator needs to brake emergently, he/she only needs to revolve the protection plate 14 towards outside of the bare casing 101, and stop the bulge 141 on the protection plate 14 from pushing against the trigger knob 15. In this way, the trigger knob 15 cannot press the contact on the protection power switch 3 anymore, thus turning off the protection power switch 3 and cutting off the power supply circuit of the motor. Meanwhile, with the help of the connecting rod 13, the protection plate 14 pulls the second coupling 11 to move towards one side in the revolving process to tighten the brake strap 5. This makes the brake strap 5 lock the brake drum 4, preventing the motor shaft from keeping on driving the chain saw blade to revolve, finally realizing the purpose of braking, as shown in Figure 17.

[0040] The brake device in this electric chain saw in this embodiment, because of adopting the two brake units, can deal with the normal braking condition and the emergency braking condition, respectively. Besides, when one of the brake units fails, the electric chain saw of the present invention can be braked via the other brake unit, fully satisfying requirements on operation safety of the electric chain saw, greatly ensuring an operator's safety.

[0041] The two brake units in this embodiment brake the motor all via the brake strap 5 and the brake drum 4, and are meanwhile linked with the main power switch 2 and the protection power switch 3 of the electric chain saw, respectively, truly attaining the purpose of braking immediately after being powered off, characteristic of quick brake, simple operation, and sensitive action. Moreover, compared to the prior art electric chain saw adopting such a brake mechanism as a clutch, a lever and a gear, the present invention is simple in the overall structure and less in the part quantity, more advantageous in miniaturization design of the electric chain saw.

Claims

1. An electric chain saw comprising a casing (1) as well as a motor and the brake device thereof installed in the casing (1); wherein the brake device includes the following parts:

a brake drum (4) sleeved on and revolving together with a motor shaft; and

a brake strap (5) sleeved on outer edge of the brake drum (4), with one end connected with a first brake unit and the other end with a second brake unit.

2. The electric chain saw according to claim 1, wherein:

the casing (1) is provided inside with a main power switch (2) serially connected with the motor; the first brake unit includes a first coupling (6), a first elastic member (7), a button (8) and a driving member (9); the first coupling (6) is fixed on the brake strap (5); the button (8) and the driving member (9) are connected with the casing (1) via a pivot (19) and a pivot (20), respectively; the button (8), opposite at one end to a contact on the main power switch (2), is provided at the other end with a molded main tooth section (801); the driving member (9), opposite at one end to one end of the first coupling (6), is provided at the other end with a molded secondary tooth section (901) engaged with the main tooth section (801); and the first elastic member (7), located between the other end of the first coupling (6) and the casing (1), provides an elastic force that drives the first coupling (6) to move towards one side to tighten the brake strap (5).

3. The electric chain saw according to claim 2, wherein the casing (1) is provided inside with a first passage (10) that guides the first coupling (6) to perform rectilinear motion.

4. The electric chain saw according to claim 3, wherein the first elastic member (7) is a spring, through which goes one end of the brake strap (5) before being fixed on the first coupling (6) via a first fixing pin (17); the first passage (10) has an end wall on both sides; and the spring is propped at one end against the first coupling (6) and at the other end against the end wall on one side of the first passage (10).

5. The electric chain saw according to claim 4, wherein the first coupling (6) is provided at one end with a first shrinkage pool (601) into which the spring can be propped and at the other end with a molded convex section (602); and this convex section (602), extending out of a pilot hole on the end wall on the other side of the first passage (10), is opposite to an extension handle (902) molded on the driving member (9).

6. The electric chain saw according to claim 1, 2, 3, 4 or 5, wherein:

the casing (1) is provided inside with a protection power switch (3) serially connected with the motor; the second brake unit includes a second coupling (11), a second elastic member (12), a connecting rod (13), a protection plate (14) and a trigger knob (15); the second coupling (11) is fixed on the brake strap (5); the protection plate (14) is connected with the casing (1) via the pivot (21), with one end exposed outside the casing (1) and the other end pin-connected with one end of the connecting rod (13); the connecting rod (13) is pin-connected at the other end with one end of the second coupling (11); the second elastic member (12), propped between the other end of the second coupling (11) and the casing (1), provides an elastic force that drives the second coupling (11) to move towards one side to tighten the brake strap (5); and the trigger knob (15) is connected with the casing (1) via the pivot, with one end opposite to a contact on the protection power switch (3) and the other end controlled by a bulge (141) molded on the protection plate (14).

7. The electric chain saw according to claim 6, wherein the casing (1) is provided inside with a second passage (16) that guides the second coupling (11) to perform rectilinear motion.

8. The electric chain saw according to claim 7, wherein the second elastic member (12) is a spring, through which goes one end of the brake strap (5) before being fixed on the second coupling (11) via a second fixing pin (18); the second passage (16) has an end wall on both sides; and the spring is propped at one end against the second coupling (11) and at the other end against the end wall on one side of the second passage (16).

9. The electric chain saw according to claim 8, wherein the second coupling (11) is provided at one end with a second shrinkage pool (111) into which the spring can be propped and at the other end with a molded pin-connected handle (112); and the pin-connected handle (112), extending out of a pilot hole on the end wall on the other side of the second passage (16), is pin-connected with the connecting rod (13).

10. An electric chain saw that can be braked normally, comprising a casing (1) and a brake device therein; the casing (1) includes a bare casing (101) and a rear handle (103) integrated with the bare casing (101); the bare casing (101) is provided inside with a motor; and the rear handle (103) is provided inside with a main power switch (2) serially connected with the motor; wherein the brake device includes the following parts:

a brake drum (4) sleeved on and revolving together with a motor shaft; and

a brake strap (5) sleeved on outer edge of the brake drum (4), with one end connected with a first brake unit; the first brake unit includes the following parts:

a button (8) pivotally connected with the rear handle (103), with one end corresponding to the main power switch (2) and the other end provided with a molded main tooth section (801);

a driving member (9) pivotally connected with the bare casing (101), with one end provided with a secondary tooth section (901) fitted with the main tooth section (801) and the other end with an extension handle (902); and

a first coupling (6) movably installed in the bare casing (101), connected with one end of the brake strap (5), and propped against an extension handle (902) of the driving member (9).

11. The electric chain saw that can be braked normally according to claim 10, wherein it further includes a first elastic member (7); and the first coupling (6) is provided at one end with a first shrinkage pool (601) into which the first elastic member (7) can be propped and at the other end with a molded convex section (602).

Drawing