Field of the Invention
[0001] The present invention relates to a technical field of a power tool in the mechanical
industry, and more particularly, to a multi-function tool for various operations such
as cutting and sanding and its quick-exchange structure.
Background of the Invention
[0002] The multi-function tool can load and clamp woodworking saw blade, metal saw blade,
triangular sand disc and the like. Then the woodworking saw blade or metal saw blade
loaded on the multi-function tool can cut the wood or the metal material such as aluminum
alloy while the triangular sand disc loaded can sand and polish the board, gypsum
board or wall.
[0003] The saw blade and the triangular sand disc are mounted on an output shaft of the
multi-function tool and the output end face of the output shaft has small bosses uniformly
distributed in a circle. The small bosses are used for the positioning of the saw
blade and the triangular sand disc. Further, threaded holes are cut on the output
shaft and with a hexagonal wrench to tighten the screws, the saw blade or the triangular
sand disc is fixed.
[0004] When you replace the saw blade or the triangular sand disc, all the screws have to
be removed, and then the new triangular sand disc or saw blade is loaded and the screws
are again tightened with the hex wrench. So the replacement of the triangular sand
disc and the saw blade is not efficient, and the hexagonal wrench is easy to lose
to have the multi-function tool not workable.
Summary of the Invention
[0005] The technical problem to be solved by the present invention is that: to overcome
the technical problem of insufficient efficiency of the replacement of saw blades
of the multi-function tool of the prior art, the present invention provides a quick
exchange structure to quickly exchange and clamp the saw blade but needing no screws
to fix the saw blade and its tools.
[0006] The technical proposal employed by the invention to solve the technical problem is
as below: a quick exchange structure for a multi-function tool, comprising an output
shaft assembly in which an elastic collet able to do axial movement is arranged. In
the collet a locking shaft is arranged, and the locking shaft is driven to move axially
within the elastic collet by an elastic assembly to realize the opening and closing
of the elastic collet. By the traditional replacement method, the screws tightening
the saw blade or the triangle disc have to be completely removed before the new one
is loaded and tightened with a hexagonal wrench. Not only the efficiency is high enough,
but also the hexagonal wrench is easy to lose, resulting in the failure of the multi-function
tool. The invention needs no screw to fix the saw blade, instead, by rotating rotary
knob arranged on the head of the structure, the axial sliding movement of the output
shaft assembly and the locking assembly is controlled to release or clamp the saw
blade and realize quick exchange.
[0007] Further, to facilitate the structural design of the present invention and have the
elastic collet and the elastic assembly only axially sliding rather than axially rotating,
the following improvements are made: the output shaft assembly comprises a main output
shaft and an auxiliary output shaft which are in an integrated structure, the upper
part of the auxiliary output shaft is within the lower end of the main output shaft
and so the external diameter is larger than the internal diameter of the main output
shaft and the internal diameters of the upper part and the lower part are identical.
On the inner wall of the main output shaft symmetrical longitudinal straight slots
are cut.
[0008] The specific structure of the elastic collet to clamp articles is as follows: the
elastic collet has an integrated annulus card and an elastic claw arranged under the
annulus card. The internal diameters of the annulus card and the elastic claw are
identical and matched with the external diameter d of the locking shaft. On the outer
ring of the annulus card annulus bosses are symmetrically arranged and the annulus
bosses slide upwards and downwards along the longitudinal straight slots. The bottom
of the elastic claw has a round step which is at the outer side of the auxiliary output
shaft, and the external diameter of the round step is slightly smaller than the internal
diameter of the auxiliary output shaft.
[0009] The elastic claw is composed of two arc bodies in symmetric shape and the outer contour
is columnar. The external diameter of the outer contour is slightly smaller than the
internal diameter of the auxiliary output shaft. The upper end face of the two arc
bodies and the lower end face of the annulus card are in an integrated structure,
and the gap between the two arc bodies forms two vertical slots. The internal and
external diameters of the elastic claw are measured in the non-opened up state of
the elastic claw, that is, the contraction state.
[0010] The structure of the elastic assembly of the invention selected is as follows:
The structure comprises a check ring for fixing arranged inside the main output shaft,
a reset spring of the elastic collet, a reset spring of the locking shaft and a circlip
for hole. The check ring for fixing is above the circlip for hole and arranged on
the upper end of the locking shaft, the annulus card is under the circlip for hole,
the reset spring of the elastic collet is sheathed on the locking shaft and the two
ends contact in plane with the upper end face of the annulus card and the lower end
face of the check ring for fixing, respectively, and the reset spring of the locking
shaft is sheathed in the shaft hole of the main output shaft, and the two ends of
the reset spring contact in plane with the lower end face of the check ring for fixing
and the upper end face of the circlip for hole.
[0011] The elastic assembly further comprises a pressing block arranged inside the main
output shaft. Above the pressing block a cam and a rotary knob are arranged, and the
rotary knob is fixed to the cam with screws and the pressing block is pressed tightly
against the check ring for fixing by the rotary knob and the cam. The cam has two
spiral conical faces, and any one of the two spiral conical faces can coincide with
the other spiral conical face by rotating 180°. And the bottom of the spiral conical
face has an arc catching step with a recess. The pressing block comprises a block
annulus, two block bosses and a block convex edge; the block bosses are symmetrically
arranged on the upper end face of the block annulus, and the upper end of the block
annulus is arc like and matched with the arc catching step; the block bosses are symmetrically
arranged on the outer ring of the block annulus and slip upwards and downwards along
the longitudinal straight slots. The lower end face of the block annulus presses against
the upper end face of the check ring.
[0012] To clamp and locate the locking shaft, on the output shaft assembly a clamp assembly
for the elastic collet is arranged.
[0013] The clamp assembly is further improved as follows: on the lower part of the auxiliary
output shaft at least two clamping holes are cut symmetrically, and the axis of the
clamping holes is vertical to the axis of the auxiliary output shaft. The clamp assembly
for the elastic collet comprises a reset spring, a reset sheath and a fixed sheath
sheathed on the auxiliary output shaft and for stopping up the clamping holes; the
reset sheath is arranged in the clamping holes, and the reset spring is arranged in
the reset sheath.
[0014] Preferably, the auxiliary output shaft has two clamping holes and the axis of the
clamping holes is vertical to a plane A formed by the axial center line of the two
vertical slots.
[0015] To facilitate the exchange and fixing of the saw blade, downwards along the bottom
of the locking shaft a conical face and a locking shaft round step in an integrated
structure are arranged; the external diameter of the conical face increases from up
down, and the external diameter of the locking shaft round step is slightly larger
than the maximum external diameter of the conical face.
[0016] The quick exchange structure for multi-function tool further comprises a saw blade;
on one end of the saw blade an installation hole and a plurality of locating holes
with the diameter identical to the internal diameter of the auxiliary output shaft
are cut, and the locating holes are uniformly distributed along the installation hole;
and the lower end face of the auxiliary output shaft has a plurality of bosses matched
with the locating holes.
[0017] Further, to facilitate the fixing of the circlip for hole, inside the main output
shaft a check ring slot is cut and the circlip for hole is fixed inside the check
ring slot.
[0018] Further, the reset spring of the elastic collet, the reset spring of the locking
shaft and the reset spring are of a pressure spring.
[0019] Further, the check ring for fixing is fixed to the locking shaft with a spring washer
and a nut.
[0020] Further, to facilitate the installation, an upper bearing and a lower bearing are
installed on the output shaft assembly.
[0021] Further, to locating the fixing sheath, on the auxiliary output shaft and against
the lower end of the fixing sheath a round wire snap ring for shaft is arranged to
locate the fixing sheath.
[0022] A multi-function tool installed with the quick exchange structure, comprising an
enclosure inside which a power unit and a mechanical drive unit are arranged. The
mechanical drive unit comprises a quick exchange structure and a shifting fork, and
the shifting fork is sheathed on the main output shaft and is connected with the power
unit.
[0023] The present invention has the following beneficial effect: compared with the prior
art, the multi-function tool and its quick exchange structure of the invention has
spared the lock screws and a hexagon wrench, and instead uses an elastic collet to
lock the saw blade; further the multi-function tool and its quick exchange structure
has compact structure and easy operation, and the saw blade is installed or removed
only by rotating the rotary knob, so remarkably increasing the work efficiency.
Brief Description of the Drawing
[0024] Below is the further description of the present invention based on the drawing and
the embodiments.
Figure 1 is a three-dimension structural drawing of the saw blade in a released state
of the quick exchange structure of the multi-function tool of the invention.
Figure 2 is a three-dimension structural drawing of the saw blade in a clamped state
of the quick exchange structure of the multi-function tool of the invention.
Figure 3 is a structural drawing of the multi-function tool in a released state of
the invention.
Figure 4 is a structural drawing of the multi-function tool in a clamped state of
the invention.
Figure 5 is a cross-section drawing of A-A in Figure 4.
Figure 6 is a cross-section drawing of B-B in Figure 6.
Figure 7 is a three-dimension structural drawing of the output shaft and the circlip
for hole of the quick exchange structure of the multi-function tool of the invention.
Figure 8 is a diagrammatic drawing of Plane A.
[0025] In the drawings: 1. Auxiliary output shaft; 2. Rotary knob; 3. Upper bearing; 4.
Pressing block; 5. Cam; 6. Screw; 7. Nut; 8. Spring washer; 9. Check ring for fixing;
11. Reset spring of locking shaft; 10. Locking shaft; 12. Shifting fork; 13. Reset
spring of elastic collet; 14. Main output shaft; 15. Circlip for hole; 16. Elastic
collet; 18. Lower bearing; 19. Fixing sheath; 21. Round wire snap ring for shaft;
22. Saw blade; 23. Conical face; 24. Boss; 25. Reset spring; 26 Reset sheath; 27.
Clamping hole; 29. Longitudinal straight slot; 32. Annulus convex edge; 35. Installation
hole; 36. Locating hole; 37. Round step of elastic claw; 38. Round step of locking
shaft; 39. Check ring slot; 40. Vertical slot; 41. Block annulus; 42. Block boss;
43. Block convex edge; 45. Elastic claw; 46. Annulus card; 50. Enclosure; 51. Spiral
conical face; 52. Arc catching step.
Description of Preferred Embodiments
[0026] Below is detailed description of the invention based on the drawings. And the drawings
are simplified diagrammatic drawings to illustrate the basic structure of the invention
and so only the structures related to the invention are displayed.
[0027] As shown in Figure 1-8, in the preferable embodiments of the invention, in the output
shaft assembly of the quick exchange structure for the multi-function tool an elastic
collet 16 able to do axial movement is arranged. In the elastic collet 16 a locking
shaft 10 is arranged, and the locking shaft 10 is driven to move axially within the
elastic collet 16 by an elastic assembly to so to realize the opening and closing
of the elastic collet 16.
[0028] The details are provided as follows:
The output shaft assembly comprises the main output shaft 14 and the auxiliary output
shaft 1 which are in an integrated structure, the upper part of the auxiliary output
shaft 1 is within the lower end of the main output shaft 14 and so the external diameter
is larger than the internal diameter of the main output shaft 14 (not larger than
the external diameter of the main output shaft 14, and if so, the upper bearing and
the lower bearing and the fixing sheath will not be installed onto the main output
shaft), and the internal diameters of the upper part and the lower part are identical.
On the inner wall of the main output shaft 14 symmetrical longitudinal straight slots
29 are cut. Further the output shaft assembly has the upper bearing 3 and the lower
bearing 18.
[0029] The elastic collet 16 has the integrated annulus card 46 and the elastic claw 45
arranged under the annulus card 46. The internal diameters of the annulus card 46
and the elastic claw 45 are identical and matched with the external diameter d of
the locking shaft 10. On the outer ring of the annulus card 46 the annulus convex
edges 32 are arranged and the annulus convex edges 32 slide upwards and downwards
along the longitudinal straight slots 29. The bottom of the elastic claw 45 has the
round step 37 of elastic claw which is at the outer side of the auxiliary output shaft
1, and the external diameter of the round step 37 of elastic claw is slightly smaller
than the internal diameter of the auxiliary output shaft 1 (to ease the installation).
The elastic claw 45 is composed of two arc bodies in symmetric shape and the outer
contour is columnar. The external diameter of the outer contour is slightly smaller
than the internal diameter of the auxiliary output shaft 1, subject to that the elastic
claw 45 can be opened up to some angles. The upper end face of the two arc bodies
and the lower end face of the annulus card 46 are in an integrated structure, and
the gap between the two arc bodies forms two vertical slots 40.
[0030] The spring assembly comprises the check ring for fixing 9 arranged inside the main
output shaft 14, the reset spring 13 of the elastic collet, the reset spring 11 of
the locking shaft and the circlip for hole 15. The check ring slot 39 is cut on the
inner ring of the main output shaft 14, the circlip for hole 15 is fixed in the check
ring slot 39 and some part extends out of the check ring slot 39, the check ring for
fixing 9 is fixed onto the locking shaft 10 with the spring washer 8 and the nut 7;
the annulus card 46 is under the circlip for hole 15, the reset spring 13 of the elastic
collet is sheathed on the locking shaft 10 and the two ends contact in plane with
the upper end face of the annulus card 46 and the lower end face of the check ring
for fixing 9, respectively, and the reset spring 11 of the locking shaft is sheathed
in the shaft hole of the main output shaft 14, and the two ends contact in plane with
the lower end face of the check ring for fixing 9 and the upper end face of the circlip
for hole 15.
[0031] The elastic assembly further comprises the pressing block 4 arranged inside the main
output shaft 14. Above the pressing block 4 a cam 5 and a rotary knob 2 are arranged,
and the rotary knob 2 is fixed to the cam 5 with screws 6 and the pressing block 4
is pressed tightly against the check ring for fixing 9 by the rotary knob 2 and the
cam 5.
[0032] The cam 5 has two spiral conical faces 51, and any one of the two spiral conical
faces 51 can coincide with the other spiral conical face 51 by rotating 180°. And
the bottom of the spiral conical face 51 has an arc catching step 52 with a recess.
The pressing block 4 comprises the block annulus 41, two block bosses 42 and the block
convex edge 43 which are integrated; the block bosses 42 are symmetrically arranged
on the upper end face of the block annulus 41, and the upper end of the block boss
42 is arc like and matched with the arc catching step 52; the block convex edge 43
is symmetrically arranged on the outer ring of the block annulus 41 and slips upwards
and downwards along the longitudinal straight slots 29. The lower end face of the
block annulus 41 presses against the upper end face of the check ring 9.
[0033] On the output shaft assembly the clamping assembly of the elastic collet is further
arranged. On the lower part of the auxiliary output shaft 1 at least two clamping
holes 27 are cut symmetrically, and the axis of the clamping holes 27 is vertical
to the axis of the auxiliary output shaft 1. The clamp assembly for the elastic collet
comprises the reset spring 25, the reset sheath 26 and the fixed sheath 19 sheathed
on the auxiliary output shaft 1 and for stopping up the clamping holes 27; on the
auxiliary output shaft 1 and against the lower end of the fixed sheath 19 the round
wire snap ring for shaft 21 is further arranged for locating the fixed sheath 19;
the reset sheath 26 is arranged in the clamping holes 27, and the reset spring 25
is arranged in the reset sheath 26. When two clamping holes 27 are cut, the push force
generated by the reset spring drives the reset sheath 26 against the two sides of
the elastic claw 45 tightly so to clamp the locking shaft 10. A plurality of clamping
holes 27 may be arranged symmetrically if required.
[0034] Downwards along the bottom of the locking shaft 10 the conical face 23 and the locking
shaft round step 38 in an integrated structure are arranged; the external diameter
of the conical face 23 increases from up down, and the external diameter of the locking
shaft round step 38 is slightly larger than the maximum external diameter of the conical
face 23.
[0035] The quick exchange structure for multi-function tool further comprises the saw blade
22; on one end of the saw blade 22 the installation hole 35 and a plurality of locating
holes 36 with the diameter identical to the internal diameter of the auxiliary output
shaft 1 are cut, and the locating holes are uniformly distributed along the installation
hole 35; and the lower end face of the auxiliary output shaft 1 has a plurality of
bosses 24 matched with the locating holes 36.
[0036] The reset spring 13 of the elastic collet, the reset spring 11 of the locking shaft
and the reset spring 25 are of a pressure spring.
[0037] A multi-function tool installed with the quick exchange structure of the embodiment,
comprising the enclosure 50 inside which the power unit and the mechanical drive unit
are arranged. The mechanical drive unit comprises the quick exchange structure and
the shifting fork 12, and the shifting fork 12 is sheathed on the main output shaft
14 and is connected with the power unit.
[0038] The functions realized by the embodiment are as follows:
The rotary knob 2 rotates counterclockwise to the end, the cam 5 rotates simultaneously
as driven by the rotary knob 2, the two symmetric spiral conical faces 51 push the
two block bosses 42 on the pressing block 4 and further have the pressing block 4
to move axially, the pressing block 4 pushes the locking shaft assembly to move outwards
and the reset spring 13 of the elastic collet simultaneously pushes the elastic collet
16 to move outwards; the elastic claw 45 of the elastic collet 16 contracts inwards
under the action of the reset spring 25 and the reset sheath 26; and so when the elastic
collet 16 is at the contraction state, the saw blade can be removed or installed then.
[0039] When the elastic collet 16 is at the contraction state, the locating holes 36 of
the saw blade 22 are sheathed on the boss 24 at the lower end face of the auxiliary
output shaft 1; then the rotary knob is rotated to the end clockwise, and so the symmetric
spiral conical faces 51 on the cam 5 are separated from the two block bosses 42; the
locking shaft assembly move inwards under the action of the reset spring 11 of the
locking shaft to reset, and the elastic claw 45 under the joint action of the reset
spring 13 of the elastic collet and the conical face 23 of the locking shaft 10 opens
up; after the elastic collet 45 opens up, the elastic collet 16 moves inwards as pushed
by the round step 38 of the locking shaft 10, the round step 37 of the elastic claw
on the elastic collet 16 presses against the edge of the round hole 35 on the saw
blade 22 and finally the saw blade 22 is locked tightly.
[0040] As enlightened by the preferable embodiment of the invention and based on the above
description, related technical workers may make various alterations and modifications
without a deviation from the spirit of the present invention. The technical range
of the present invention is not limited to the descriptions of the patent specification
and must be determined based on the range of the claims.
1. A quick exchange structure for a multi-function tool, wherein an output shaft assembly
in which an elastic collet (16) able to do axial movement is arranged. In the elastic
collet (16) a locking shaft (10) is arranged, and the locking shaft (10) is driven
to move axially within the elastic collet (16) by an elastic assembly to realize the
opening and closing of the elastic collet (16).
2. The quick exchange structure for a multi-function tool of Claim 1, wherein the output
shaft assembly comprises a main output shaft (14) and an auxiliary output shaft (1)
which are in an integrated structure, the upper part of the auxiliary output shaft
(1) is within the lower end of the main output shaft (14) and so the external diameter
is larger than the internal diameter of the main output shaft (14) and the internal
diameters of the upper part and the lower part are identical, and on the inner wall
of the main output shaft (14) symmetrical longitudinal straight slots (29) are cut.
3. The quick exchange structure for a multi-function tool of Claim 2, wherein the elastic
collet (16) has an integrated annulus card (46) and an elastic claw (45) arranged
under the annulus card (46), the internal diameters of the annulus card (46) and the
elastic claw (45) are identical and matched with the external diameter d of a locking
shaft (10), on the outer ring of the annulus card (46) annulus convex edges (32) are
arranged and the annulus convex edges (32) slide upwards and downwards along longitudinal
straight slots (29), and the bottom of the elastic claw (45) has a round step (37)
of elastic claw which is at the outer side of an auxiliary output shaft (1)
4. The quick exchange structure for a multi-function tool of Claim 3, wherein the elastic
claw (45) is composed of two arc bodies in symmetric shape and the outer contour is
columnar, the external diameter of the outer contour is slightly smaller than the
internal diameter of the auxiliary output shaft (1), the upper end face of the two
arc bodies and the lower end face of the annulus card (46) are in an integrated structure,
and the gap between the two arc bodies forms two vertical slots (40).
5. The quick exchange structure for a multi-function tool of Claim 3, wherein the spring
assembly comprises a check ring for fixing (9) arranged inside the main output shaft
(14), a reset spring (13) of the elastic collet, a reset spring (11) of the locking
shaft and a circlip for hole (15), the check ring for fixing (9) is above the circlip
for hole (15) and fixed onto the upper end of the locking shaft (10), the annulus
card (46) is under the circlip for hole (15), the reset spring (13) of the elastic
collet is sheathed on the locking shaft (10) and the two ends contact in plane with
the upper end face of the annulus card (46) and the lower end face of the check ring
for fixing (9), respectively, and the reset spring (11) of the locking shaft is sheathed
in the shaft hole of the main output shaft (14), and the two ends contact in plane
with the lower end face of the check ring for fixing (9) and the upper end face of
the circlip for hole (15).
6. The quick exchange structure for a multi-function tool of Claim 4, wherein the elastic
assembly further comprises a pressing block (4) arranged inside the main output shaft
(14), above the pressing block (4) a cam (5) and a rotary knob (2) are arranged, and
the rotary knob (2) is fixed to the cam (5) with screws (6) and the pressing block
(4) is pressed tightly against the check ring for fixing (9) by the rotary knob (2)
and the cam (5).
7. The quick exchange structure for a multi-function tool of Claim 6, wherein the cam
(5) has two spiral conical faces (51), and any one of the two spiral conical faces
(51) can coincide with the other spiral conical face (51) by rotating 180°, the bottom
of the spiral conical face (51) has an arc catching step (52) with a recess, the pressing
block (4) comprises a block annulus (41), two block bosses (42) and a block convex
edge (43) which are integrated; the block bosses (42) are symmetrically arranged on
the upper end face of the block annulus (41), and the upper end of the block boss
(42) is arc like and matched with the arc catching step (52); the block convex edge
(43) is symmetrically arranged on the outer ring of the block annulus (41) and slips
upwards and downwards along the longitudinal straight slots (29), and the lower end
face of the block annulus (41) presses against the upper end face of the check ring
(9).
8. The quick exchange structure for a multi-function tool of Claim 2, wherein on the
output shaft assembly a clamp assembly for the elastic collet is further arranged.
9. The quick exchange structure for a multi-function tool of Claim 8, wherein on the
lower part of the auxiliary output shaft (1) at least two clamping holes (27) are
cut symmetrically, and the axis of the clamping holes (27) is vertical to the axis
of the auxiliary output shaft (1), the clamp assembly for the elastic collet comprises
a reset spring (25), a reset sheath (26) and a fixed sheath (19) sheathed on the auxiliary
output shaft (1) and for stopping up the clamping holes (27); the reset sheath (26)
is arranged in the clamping holes (27), and the reset spring (25) is arranged in the
reset sheath (26).
10. The quick exchange structure for a multi-function tool of Claim 9, wherein two clamping
holes (27) are cut and the axis of the clamping holes (27) is vertical to a plane
A formed by the axial center line of the two vertical slots (40).
11. The quick exchange structure for a multi-function tool of Claim 1, wherein downwards
along the bottom of the locking shaft (10) a conical face (23) and a locking shaft
round step (38) in an integrated structure are arranged; the external diameter of
the conical face (23) increases from up down, and the external diameter of the locking
shaft round step (38) is slightly larger than the maximum external diameter of the
conical face (23).
12. The quick exchange structure for a multi-function tool of Claim 2, wherein the quick
exchange structure for multi-function tool further comprises a saw blade (22), on
one end of the saw blade (22) the installation hole (35) and a plurality of locating
holes (36) with the diameter identical to the internal diameter of the auxiliary output
shaft (1) are cut, and the locating holes are uniformly distributed along the installation
hole (35), and the lower end face of the auxiliary output shaft (1) has a plurality
of bosses (24) matched with the locating holes (36).
13. The quick exchange structure for a multi-function tool of Claim 4, wherein inside
the main output shaft (14) a check ring slot (39) is cut and the circlip for hole
(15) is fixed inside the check ring slot (39).
14. The quick exchange structure for a multi-function tool of Claim 9, wherein the reset
spring (13) of the elastic collet, the reset spring (11) of the locking shaft and
the reset spring (25) are of a pressure spring.
15. The quick exchange structure for a multi-function tool of Claim 5, wherein the check
ring for fixing (9) is fixed to the locking shaft (10) with a spring washer (8) and
a nut (7).
16. The quick exchange structure for a multi-function tool of Claim 1, wherein an upper
bearing (3) and a lower bearing (18)are installed on the output shaft assembly.
17. The quick exchange structure for a multi-function tool of Claim 9, wherein on the
auxiliary output shaft (1) and against the lower end of the fixing sheath (19) a round
wire snap ring for shaft (21) is arranged to locate the fixing sheath (19).
18. A multi-function tool in which the quick exchange structure mentioned in any claim
of Claims 1-17 is installed, wherein the multi-function tool comprises an enclosure
(50) inside which a power unit and a mechanical drive unit are arranged, the mechanical
drive unit comprises a quick exchange structure and a shifting fork (12), and the
shifting fork (12) is sheathed on the main output shaft (14) and is connected with
the power unit.