Improved electric knife

Abstract

Electric knife, comprising a knife body (1), forming a handle housing an electric motor (2), and a blade holder (3), received in the handle, carrying a blade (4) and operated by the motor through a device (5) for transforming rotary movement of the motor into reciprocating movement of the blade holder, for which the knife comprises an axis (6) perpendicular to the blade, around which the blade holder (3) pivots, for which the blade holder (3) comprises a rear end (3a) on the handle side provided with transverse stops (31a, 31b) and a front end (3b) from which the blade protrudes, the movement transformation device (5) comprising a rod (8) connected to an output shaft (9) of the motor, eccentric relative to and parallel to the output shaft, and for which the rod (8) set in motion by the output shaft acts alternately on the transverse stops (31a,31b) of the blade holder for maneuvering the rear end of the blade holder back and forth in a direction perpendicular to the edge of the blade and in the plane of the blade, said rod (8) acting on the transverse stops (31a, 31b) of the blade holder by means of a bearing (10) centered on the rod and whose external cage (10a) is positioned between said transverse stops (31a, 31b), characterized in that the rod (8) being constituted by a tenon mounted eccentrically on a disc (11) fixed axially on the motor shaft (9) and centered on the motor shaft, a balancing weight (111) is produced on a sector of said disc in a position diametrically opposite the rod (8) relative to said motor shaft (9).,

Description

Technical field

[0001] The present invention relates to an electric knife, that is to say a knife whose blade is operated by an electric motor in order to assist the operator in his cutting task.

[0002] The invention applies in particular to cardboard cutting knives with replaceable blades. Prior art

[0003] An electric knife suitable for cutting thick cardboard, in particular two- or three-layer cardboard, is known from document EP3326768 B1, which proposes an electric knife comprising a blade mounted on a blade holder operated by an electric motor via a device for transforming a rotational movement of the motor into an alternating movement of the blade holder, configured so that the blade holder is moved in rotation and back and forth relative to a fixed shaft secured to a body of the knife, which imparts an oscillating movement to the blade.

[0004] In this document, the blade oscillates or vibrates in a transverse direction in the plane of the blade unlike the prior art in which the blade moves longitudinally in the plane of the blade in the manner of a saw. According to the example shown, the motion transformation device comprises a rod connected to an output shaft of the motor, eccentric with respect to and parallel to the output shaft and adapted to oscillate the blade holder around the fixed shaft. The rod moved by the output shaft acts alternately on transverse stops of the blade holder to maneuver the rear end of the blade holder back and forth in a direction perpendicular to the edge of the blade and in the plane of the blade by means of a bearing centered on the rod and whose outer cage is positioned between said stops to communicate to the blade holder a continuous sinusoidal oscillatory movement during the rotation of the motor shaft.The rod consists of a tenon mounted eccentrically on a disc fixed axially to the motor shaft and centered on the motor shaft. Technical problem

[0005] This device is effective but causes vibrations in the knife body. Similarly, greater rigidity of the fixed axis guidance is desired. Statement of the invention

[0006] To overcome these problems, the present disclosure proposes an improved electric knife which comprises a knife body, forming a handle housing an electric motor, and a blade holder, received in the handle, carrying a blade and operated by the motor through a device for transforming the rotary movement of the motor into reciprocating movement of the blade holder, the knife comprises an axis perpendicular to the blade, around which the blade holder pivots, the blade holder comprises a rear end on the handle side provided with transverse stops and a front end from which the blade protrudes, the movement transformation device comprises a rod connected to an output shaft of the motor, eccentric relative to and parallel to the output shaft,the rod set in motion by the output shaft acts alternately on the transverse stops of the blade holder to maneuver the rear end of the blade holder back and forth in a direction perpendicular to the edge of the blade and in the plane of the blade, said rod acting on the transverse stops of the blade holder by means of a bearing centered on the rod and whose external cage is positioned between said transverse stops, and the rod being constituted by a tenon mounted eccentrically on a disc fixed axially on the motor shaft and centered on the motor shaft, a balancing weight is produced on a sector of said disc in a position diametrically opposite the rod relative to said motor shaft.,

[0007] The disc is advantageously extended opposite the rod by a sleeve fixed on the motor shaft and centered on the motor shaft.

[0008] According to an advantageous embodiment, said sleeve is advantageously received in an internal bearing cage, the external cage of which is embedded in a housing of an annular frame, on either side of the frame.

[0009] The blade holder may comprise a rod coaxial with said axis received freely in rotation in the internal cage of a pair of bearings mounted on either side of an annular partition in a housing of a half-shell of the body of the knife and held axially along the axis by said pair of bearings and a screw.

[0010] Furthermore, securing the operation of the knife is desirable and in particular it is necessary to eliminate the risks of triggering the operation of the knife or to guarantee that the motor cuts out when the operator releases the operating control.

[0011] To do this, the electric knife having a battery that is inserted via the rear end of the knife body and an electronic motor control board has a first switch actuated by a first trigger and a second switch actuated by a second trigger.

[0012] Preferably, one of said triggers is arranged on top of the body of the knife, the other of said triggers is arranged under the body of the knife, knife in cutting position with the blade edge facing downwards.

[0013] According to an advantageous embodiment, one of said switches cuts one of the power circuits supplying the motor when the corresponding trigger is released and the other of said switches cuts the power supply to said electronic card when the corresponding trigger is released.

[0014] According to a preferred embodiment, the electronic card is powered and the motor is started by pressing the two switches with the two triggers pressed. Brief description of the drawings

[0015] Other features and advantages of the disclosed embodiment will become apparent upon reading the following description of a non-limiting aspect of the disclosed embodiment with reference to the drawings which show: [ Fig. 1 ] a side view of an electric knife of the present disclosure; [ Fig. 2 ] an exploded view of the knife of the Figure 1 ; [ Fig. 3 ] an exploded view of a knife movement transformation mechanism; [ Fig. 4 ] a view of a detail of the mechanism of the Figure 3 ; [ Fig. 5 ] a perspective view of a half-shell of the knife with blade holder; [ Fig. 6 ] a perspective view of a battery pack and motor control of the electric knife. Description of embodiments

[0016] An electric knife according to the embodiment presented here is shown in Figure 1 . It comprises a battery 14, a knife body 1, a pivoting protection device 101 protecting a blade 4 seen in Figure 2 and relaxations 15a, 15b discussed later.

[0017] The knife body 1 forming a handle has a longitudinal axis extending from the battery towards the protection device and a transverse axis, for example extending from one of the triggers located on a bottom of the knife body, blade positioned downwards according to the Figure 1 towards the other of the triggers located on the top of the knife body.

[0018] Related to the Figure 2 , in the body of the knife are arranged an electric motor 2, for example a direct current motor comprising a rotating output shaft 9, a movement transformation mechanism 5 and a blade holder 3 which carries a blade 4.

[0019] The blade holder has a rear end 3a in the body of the knife and a front end 3b projecting from the front of the body of the knife and which carries the blade 4 itself projecting from the front of the knife.

[0020] According to the Figure 6 and in a rear part of the knife are the motor and an electronic card 16 on which is mounted a connector 163 provided with pins 164 inserting into female contacts 141 of the battery 14 which is inserted at the rear of the body of the knife.

[0021] The knife comprises a motion transformation device 5 which transforms the rotary motion of an output shaft 9 of the motor into an oscillating motion of the blade holder 3 and therefore of the blade 4 in the plane of the blade holder. This motion transformation device 5 is more particularly described in figures 2 And 3 .

[0022] To achieve the transformation of said movement, the body of the knife comprises an axis 6 perpendicular to the blade, around which the blade holder 3 pivots, and the blade holder 3 comprises, at its rear end, transverse stops 31a, 31b. The movement transformation device 5 comprises a rod 8 received in the internal cage of a bearing 10 centered on the rod and the external cage of which is positioned between said stops 31a, 31b.

[0023] This rod 8, eccentric relative to the output shaft 9 to which it is attached, acts alternately on the transverse stops 31a, 31b of the blade holder to maneuver the rear end of the blade holder back and forth in a direction perpendicular to the edge of the blade and in the plane of the blade.

[0024] The rod 8 is constituted by a tenon mounted eccentrically on a disc 11 fixed axially on the motor shaft 9 by a sleeve 8' and centered on the motor shaft. The disc 11 is provided with a balancing weight 111 produced on a sector of said disc in a position diametrically opposite the rod 8 relative to said motor shaft 9.

[0025] The sleeve 8' is received in the internal bearing cages 12, 12', the external cages of which are embedded in a housing of an annular frame 13 fixed in the body of the knife and centered relative to the output shaft of the motor.

[0026] According to the Figure 5the blade holder 3 comprises, to allow its oscillation, a rod 61 coaxial with said axis 6 and which is received freely in rotation in the internal cage of a pair of bearings mounted on either side of an annular partition 19a in a housing 19 of a half-shell 1a of the body of the knife. The rod 61 is held axially along the axis 6 by said pair of bearings 7a, 7b and by a screw 71 which is inserted and tightened in a thread of the rod 61. This assembly makes it possible to ensure a firm hold of the blade holder relative to the body of the knife while allowing it to rotate back and forth around the axis 6. The rod 8, eccentric relative to the output shaft 9 of the motor and connected to it by the sleeve 8', alternately pushes the stops 31a, 31b during the rotation of the output shaft of the motor, which thus causes the blade holder and therefore the blade to oscillate around the axis 6.

[0027] Back to the Figure 6, the motor is controlled by a safety device comprising two push switches 161, 162 positioned on the electronic card 16 and controlled by triggers or triggers 15a, 15b, one of which is on the upper part or above the body of the knife and the other on the lower part or below the body of the knife.

[0028] The switches are spring-loaded momentary pushbuttons that break the circuit to which they are connected when released and turn it on when pressed. In the disclosed embodiment, the switches stop the motor when released.

[0029] This provides a safety feature as the engine only starts if the operator presses both triggers activating the push buttons and stops as soon as the operator releases at least one of the push buttons.

[0030] In the chosen configuration, one of the switches cuts the motor power circuit when released, for example switch 161 corresponding to the trigger under the body of the knife. The other of the switches, for example switch 162 associated with the trigger on the top of the body of the knife controls the powering up of the electronic motor control card.

[0031] This system provides double safety. In fact, on the one hand the operator must firmly press the knife to press the two triggers located above and below the knife in order to operate the knife and on the other hand, even if a component of the electronic card led to a short circuit of the card control, the switch which cuts the power circuit would stop the rotation of the motor when the operator releases the handle.

[0032] The invention is not limited to the example shown and in particular the body of the knife can be straight or curved while remaining within the scope of the invention.

Claims

1. Electric knife, comprising a knife body (1), forming a handle housing an electric motor (2), and a blade holder (3), received in the handle, carrying a blade (4) and operated by the motor through a device (5) for transforming rotary movement of the motor into reciprocating movement of the blade holder, for which the knife comprises an axis (6) perpendicular to the blade, around which the blade holder (3) pivots, for which the blade holder (3) comprises a rear end (3a) on the handle side provided with transverse stops (31a, 31b) and a front end (3b) from which the blade protrudes, the movement transformation device (5) comprising a rod (8) connected to an output shaft (9) of the motor, eccentric relative to and parallel to the output shaft, and for which the rod (8) set in motion by the output shaft acts alternately on the transverse stops (31a,31b) of the blade holder to maneuver the rear end of the blade holder back and forth in a direction perpendicular to the edge of the blade and in the plane of the blade, said rod (8) acting on the transverse stops (31a, 31b) of the blade holder by means of a bearing (10) centered on the rod and whose external cage (10a) is positioned between said transverse stops (31a, 31b), , characterized in that the rod (8) being constituted by a tenon mounted eccentrically on a disc (11) fixed axially on the motor shaft (9) and centered on the motor shaft, a balancing weight (111) is produced on a sector of said disc in a position diametrically opposite the rod (8) relative to said motor shaft (9).

2. Electric knife according to claim 1, for which, on the motor side, the disc (11) is extended opposite the rod by a sleeve (8') fixed on the motor shaft (9) and centered on the motor shaft.

3. Electric knife according to claim 2, for which said sleeve (8') is received in an internal cage of bearings (12, 12') whose external cage is embedded in a housing of an annular frame (13), on either side of the frame.

4. Electric knife according to claim 1 or 2, for which the blade holder comprises a rod (61) coaxial with said axis (6) received freely in rotation in the internal cage of a pair of bearings mounted on either side of an annular partition (19a) in a housing (19) of a half-shell (1a) of the body of the knife and held axially along the axis (6) by said pair of bearings (7a, 7b) and a screw (71).

5. Electric knife according to any one of the preceding claims, comprising a battery (14) which is inserted via the rear end of the body of the knife, supplying power to an electronic card (16) for controlling the motor (2) and comprising a first push switch (161) actuated by a first trigger (15a) and a second push switch (162) actuated by a second trigger, for which one of said switches (161, 162) cuts a power circuit supplying the motor when the corresponding trigger is released the other of said switches (161, 162) cuts the power supply to said electronic card (16) when the other trigger is released.

6. Electric knife according to claim 5 wherein the first trigger (15a) is positioned on a top of the body of the knife and the second trigger (15b) is arranged under the body of the knife, knife in cutting position with the blade edge facing downwards.

7. Electric knife according to claim 5 or 6, for which the electronic card is powered and the motor is started by pressing the two switches (161, 162) with the two triggers (15a, 15b) pressed.

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