Field of the invention
[0001] The present invention relates to a lifter, in particular, to a kind of chain lifter
with safe descending stroke.
Description of the Prior Art
[0002] The existing lifter achieves the ascending or descending of the bearing body by the
usual use of the chain transmission, the belt transmission, the gear transmission
or the hydraulic cylinder extension and etc. The chain transmission can work reliably
under harsh conditions such as high temperature, oil or acid and accordingly behaves
with very high adaptability owing to the ability to transmit movements and forces
under the condition that the distance between the center of two shafts is long, which
is one of the most widely used movable parts in the mechanical handling and lifting
system, for example, the lifting device of stereo garage, the lifter of logistics
equipment and the small elevator for serving diner, these devices are all equipped
with the chain transmission mechanism.
[0003] In practical applications, a Chinese Patent
CN2820819Y titled "Lifting Driving Device" (Patent Number is
ZL200520026711.2) is a classic application of the chain transmission in the garage lifting system.
The lifting driving device comprises a system box that can move up and down along
two lifting guiding rails, a group of main driving engine mounted in the middle of
the system box, a first transmission chain group, a second transmission chain group
and a pressure tension sprocket device which all driven by the main driving engine;
the whole lifting driving device is directly provided on the bottom of a lifting body;
the first transmission chain group and the second transmission are respectively engaged
on and the main shaft of the main driving engine respectively through a first chain
and a second chain; the first chain and the second chain are engaged on the main shaft
in reverse direction, which leads to the forming of equal reverse force of the first
chain and the second chain on the main shaft, according the main shaft load of the
main driving engine can be substantially eliminated, so that the service life of the
main driving engine will be prolonged. The chain transmission group in this patent
can be directly provided in the system box, it makes the lifting device can be provided
on the bottom of the lifting body through the system box, so as to substantially save
space and reduce cost, and the use of the chain transmission can reduce the load of
the main shaft of the main driving engine, so as to prolong the service life.
[0004] However, during the ascending or descending process of the lifting device in the
up stated patent, due to the gravity, the chain fixed on the top side of the stand
column keeps in tight all along, especially when the lifting device touches the ground,
owing to the lag of brake of the motor, the motor will continue to drive the chain
to rotate under the role of inertia. Accordingly, during the period from the receival
of stop signal to the complete brake, the motor continues to rotate, and makes the
chain originally in loose to turn tight and the chain originally in tight to turn
loose. As the motor continues to rotate, the chain turning loose will have increasing
looseness, and too large looseness will further lead to poor meshing and vibration
of the chain, which will cause unsteady chain transmission and even chain-disengaging.
If the motor still rotates, the chain turning tight will be stretched to crack and
can not work normally. Therefore, the adjustment of the chain looseness when the motor
brakes is failed to be considered in the lifting device in the up stated patent, that
is, the lifting device is not provided with enough safe descending stroke, which influences
the widespread use of the lifting device to some extent.
[0005] In order to solve the problem of the chain loosening, another Chinese Patent
CN201193154Y (Patent Number is
ZL200820300554.3) discloses a tensioning and centering device of the driven sprocket of the lifter.
In this device, the lower sprocket group is mounted on the lower sprocket group framework,
the slip connection is provided between the lower sprocket group and the stand column,
a tension adjustment screw is provided between the base on the bottom of the stand
column and the frame of the lower sprocket group, the top of the tension adjustment
screw is provided with a tension nut; furthermore, the joint between the main transmission
shaft and the cantilever sprocket of the lower sprocket group and the frame of the
lower sprocket group is provided with a centering device.
[0006] However, the tensioning device in this patent can only be achieved by manual adjustment,
which has the disadvantage that the looseness of the loose edge of the chain can not
be accurately obtained, it means that an accurate judgment for the descending limit
position of the lifting mechanism is required. Yet, as the running environment and
motor performance are usually different, and the triggering time of the limit switch
varies, it is hard to know the accurate descending limit position. If the looseness
of the chain after adjustment is too small, then the chain scission will occur when
the motor continues to rotate; if the looseness of the chain after adjustment is still
too large, then the vibration and even chain-disengaging will occur during the running
process. Therefore, the tension device of the up stated patent still cannot well solve
the problem of unsteady descending caused by the chain loosening, so that the safety
of the equipment during the running process still cannot be effectively guaranteed.
Summary of the invention
[0007] It is an object of the present invention to provide a chain lifter which can automatically
change the wrap angle of the chain with loose edge on the wheel/sprocket to ensure
the looseness of the chain to be kept within a given range; the chain lifter accordingly
ensures enough safety stroke during the descending process, so as to improve stability
and safety of the work of the lifter.
[0008] For achieving the above stated object, a chain lifter with safe descending stroke
comprising:
a lifting body which can move up and down along a pair of vertical guiding grooves;
a motor which is fixed on the middle of the lifting body;
a driving sprocket group, including a first driving wheel and a second driving wheel
both mounted on the output shaft of the motor, two first traction wheels respectively
disposed at two sides of the output shaft of the motor, a first tension wheel disposed
between one of the two first traction wheels and the first driving wheel, a first
chain engaged on the two first traction wheels, the first tension wheel and the first
driving wheel, two second traction wheels respectively disposed at two sides of the
output shaft of the motor, a second tension wheel disposed between one of the two
second traction wheels and the second driving wheel and located at the different side
of the first tension wheel relatively to the output shaft of the motor, a second chain
engaged on the two second traction wheels, the second tension wheel and the second
driving wheel;
characterized in that the chain lifter also comprises:
a linkage mechanism disposed between the first tension wheel and the second tension
wheel, which includes a first swing rod, a second swing rod, a first connecting rod
and a second connecting rod all disposed substantially in a same plane, a first end
of the fist swing rod is hinged with a first end of the second swing rod through a
first pin which forms a first hinge point, a first end of the second connecting rod
is hinged at the middle of the second swing rod, a second end of the first connecting
rod is hinged with a second end of the second connecting rod through a second pin
which forms a second hinge point, furthermore, the linkage mechanism also includes
an elastic resetting mechanism which makes the first hinge point and the second hinge
point keep apart with each other all along;
a first rocking rod, the first end of which is hinged on the lifting body, the second
end of which is provided with a first fixing shaft on which the first tension wheel
surround, and which the second end of the second swing rod is hinged on;
a second rocking rod, the first end of which is hinged on the lifting body, the second
end of which is provided with a second fixing shaft on which the second tension wheel
surround, and which the second end of the second swing rod is hinged on;
a first safe switch, fixed on the lifting body and located corresponding to the position
of the second rocking rod, when the lifting body touches the ground, the second rocking
rod can trigger the first safe switch to control the motor to stop;
a second safe switch, fixed on the lifting body and located corresponding to the position
of the first rocking rod, when the lifting body touches the ground and the first safe
switch fails to work, the first rocking rod can trigger the second safe switch to
control the motor to stop;
a first linkage crank; a first pulling rod; a second linkage crank; a second pulling
rod;
a first adjusting wheel for adjusting the wrap angle of the loosen edge of the first
chain on the first traction wheel, the main shaft of the first adjusting wheel is
fixed on the first end of the first linkage crank, the middle of the first linkage
crank is hinged on the lifting body, the second end of the first linkage crank is
hinged on the first end of the first pulling rod, the second end of the first pulling
rod is hinged on the first rocking rod;
a second adjusting wheel for adjusting the wrap angle of the loosen edge of the second
chain on the second traction wheel, the main shaft of the second adjusting wheel is
fixed on the first end of the second linkage crank, the middle of the second linkage
crank is hinged on the lifting body, the second end of the second linkage crank is
hinged on the first end of the second pulling rod, the second end of the second pulling
rod is hinged on the second rocking rod.
[0009] In order to reduce the volume of the device and ensure the stability of resetting,
as a preference, the elastic resetting mechanism includes a spring seat, a frame and
a spring, the spring seat is in conversed U-shape, a positioning sleeve is provided
on the top of the main body of the spring seat for the spring to surround, a guiding
column is inserted in the positioning sleeve which can slide up and down relatively
to the positioning sleeve, the upper portion of the guiding column is fixed with the
frame, the two side walls of the main body of the spring seat are respectively provided
with a lengthways guiding hole, and the bottom ends of the two side walls are respectively
provided with a first hinging holes;
the first hinge point and the second hinge point are both disposed on the two side
walls of the main body of the spring seat, and journals of the two ends of the first
pin are respectively rested in the corresponding first hinging hole, the two ends
of the second pin are respectively disposed through the corresponding lengthways guiding
hole and the second pin can slide lengthways along the lengthways guiding hole;
the frame is disposed above the main body of the spring seat, the frame can keep linkage
with the first connecting rod and the second connecting rod through the second pin,
the spring is limited between the frame and the main body of the spring seat to make
the frame keep apart with the spring seat all along.
[0010] As a result, when the second end of the first swing rod and the second end of the
second swing rod draw closely to each other under the function of the traction of
the chain, the second hinge point will move along the lengthways guiding hole and
move close to the first hinge point, and the spring is in compression state; when
the external force disappearing, under the action of the elastic resetting force of
the spring, the frame will move depart from the spring seat, and the second hinge
point will move along the lengthways guiding hole and away from the first hinge point.
[0011] In order to make the spring be assembled firmly and be positioned easily, as a preference,
the frame is designed to be conversed U-shaped, the bottom ends of the two side walls
of the frame are respectively provided with a second hinging hole, journals of the
two ends of the second pin are respectively rested in the corresponding second hinging
holes;
the upper portion of the guiding column has threads outside, the top of the frame
has a through hole for the upper portion of the guiding column to go through, and
the top of the guiding column which is above the top of the frame is threaded connected
with a first nut, the portion of the guiding column which is below the top of the
frame is threaded connected with a second nut, the first nut and the second nut make
the upper portion of the guiding column be limited in the through hole of the frame.
[0012] The first safe switch can be an electro-optical switch, or a reed ripe, or a Hall
switch or other existing common used trigger switch. As a preference, the first safe
switch is a micro switch, The first safe switch is a micro switch, the second rocking
rod includes a main portion which is parallel to the lifting body, a L-shaped bending
portion located above the main portion and bending toward the lifting body, and a
second fixing shaft which is vertically disposed on the vertical wall of the L-shaped
bending portion, the bottom of the main portion is the first end of the second rocking
rod which is hinged on the lifting body through a fourth pin, the top of the main
portion is provided with a first triggering block which can press the first safe switch.
[0013] The second safe switch can be an electro-optical switch, or a reed ripe, or a Hall
switch or other existing common used trigger switch. As a preference, the second safe
switch is a micro switch, the top of the first rocking rod is the first end of the
first rocking rod which is hinged on the lifting body through a third pin, a first
fixing shaft is disposed at the bottom of the first rocking rod, and the bottom of
the first rocking rod is provided with a second triggering block which can press the
second safe switch.
[0014] Compared with the prior art, in the present invention, the lifting body is provided
with a linkage mechanism which can reset automatically, and the looseness of the loose
edge of the chain can be automatic adjusted by collaborating with the rocking rod,
the linkage crank and the adjusting wheel; as the linkage mechanism in the present
invention is a planar four-bar linkage with the double herring bone structure, which
is small in size and can be installed in a tiny space accordingly; all hinge points
of the linkage mechanism can move freely without fixed points, therefore, the stroke
can be amplified with non-constant rate, i.e. the motor inertia can be transmitted
to the sprocket, and the rocking rod can be driven to ensure the linkage between the
pulling rod and the linkage crank, in the meanwhile, the stroke of the elastic resetting
mechanism can be changed through the linkage mechanism, and the wrap angle of the
chain on the wheel/sprocket can be changed, so as to prevent from operation fault
and accidents caused by the over-loosening or over-tightening of the chain;
[0015] As a result, the present invention can achieve the automatic adjustment to the chain
looseness through the various size of the motor inertia force, so as to avoid the
defect of improper adjustment caused by inaccurate prediction of manual adjustment,
the adjustment mode of the present invention is more flexible, reliable and accurate,
and such adjustment mode can achieve better adjustment effect, so as to ensure the
lifter to be provided with enough descending stroke when the lifter touches the ground,
and the loose edge of the chain to be kept within proper range all along.
[0016] In addition, the present invention is also provided with a double protection switch
which has a lower limit and a lower check, so that the motor can stop reliably when
the lifter touches the ground, it can increase the operation reliability and safety
of the lifter.
Brief Description of the Drawings
[0017]
FIG.1 is a perspective view of a chain lifter with safe descending stroke in accordance
with an exemplary embodiment of the present invention.
FIG2 is a perspective view of the lifting body shown in FIG.1. 1.
FIG.3 is a perspective view of the first rocking rod in accordance with the exemplary
embodiment of the present invention.
FIG.4 is a perspective view of the second rocking rod in accordance with the exemplary
embodiment of the present invention.
FIG.5 is a perspective view of a part of the linkage mechanism in accordance with
the exemplary embodiment of the present invention.
FIG.6 is an explosive view of the linkage mechanism shown in FIG.5.
FIG.7 is a sketch of the working status of the chain lifter in accordance with the
exemplary embodiment when the chain lifter does not touch the ground.
FIG.8 is a sketch of the working status of the chain lifter in accordance with the
exemplary embodiment when the chain lifter touches the ground and the first safe switch
is triggered.
FIG.9 is a sketch of the working status of the chain lifter in accordance with the
exemplary embodiment when the chain lifter touches the ground and the second safe
switch is triggered.
Detailed Description of the Preferred Embodiment
[0018] To enable a further understanding of the innovative and technological content of
the invention herein refer to the detailed description of the invention and the accompanying
drawings below:
[0019] FIG.1 ∼ FIG.9 show a chain lifter in accordance with an exemplary embodiment of the
present invention. The chain lifter comprises a lifting body (1) which can move up
and down along a pair of vertical guiding grooves (9) locating at the two sides of
the lifting body (1), a motor (2) which is fixed on the middle of the lifting body
(1), and a driving sprocket group which is disposed in the lifting body (1).
[0020] The driving sprocket group is composed of a first driving sprocket group and a second
driving sprocket group both symmetrically disposed, as shown in Fig. 1 and Fig. 7.
The detail is as below:
[0021] The first driving sprocket group includes a first driving wheel (31), two first traction
wheels (32) and a first tension wheel (33) which are all disposed in a same plane.
The first driving wheel (31) is coaxial with the output shaft of the motor, the two
first traction wheels (32) are respectively disposed at two sides of the output shaft
of the motor. The first tension wheel (33) is disposed between the first traction
wheel (32) which is disposed at the left side of the output shaft of the motor and
the first driving wheel (31). A first chain (34), the first free end of which is fixed
on the vertical guiding groove (9) below the first traction wheel (32) disposed at
the left side of the output shaft of the motor, the second free end of which moves
round the top edge of the first traction wheel (32) which is disposed at the right
side of the output shaft of the motor being engaged and extends to be fixed on the
vertical guiding groove (9).
[0022] As a result, the middle part of the first chain (34) is engaged from the first end
of the first traction wheel (32) orderly with the top edge of the first traction wheel
(32) at the left side, and with the first tension wheel (33) and the first driving
wheel (31) in S-shape, and with the bottom of the first traction wheel (32) at the
right side, finally reaching out from the bottom of the first traction wheel (32).
[0023] The second driving sprocket group includes a second driving wheel (41), two second
traction wheels (42) and a second tension wheel (43) which are all disposed in a same
plane. The second driving wheel (41) is mounted on the output shaft of the motor,
two second traction wheels (42) are respectively disposed at two sides of the output
shaft of the motor and are respectively coaxial with the corresponding first traction
wheel (32). The second tension wheel (43) is disposed between the second traction
wheel (42) disposed at the right side of the output shaft of the motor and the second
driving wheel (41).
[0024] A second chain (44), the first free end of which moves round the top edge of the
second traction wheel (42) disposed at the left side of the output shaft of the motor
being engaged and extends to be fixed on the vertical guiding groove (9), the second
free end of which is fixed on the vertical guiding groove (9) below the second traction
wheel (42) disposed at the right side of the output shaft of the motor. Accordingly,
the middle part of the second chain (44) comes out from the bottom of the second traction
wheel (42) at the left side, and is engaged orderly with the second driving wheel
(41) and the second tension wheel (43) in S-shape, and extends from the top edge of
the second traction wheel (42) at the right side finally fixed on the vertical guiding
groove (9).
[0025] At the front of the lifting body (1), a planar linkage mechanism (5) is disposed
between the first tension wheel (33) and the second tension wheel (43) (see Fig.1,
Fig.2 and Fig.5), which includes a first swing rod (51), a second swing rod (52),
a first connecting rod (53) and a second connecting rod (54) all disposed in a same
plane. A first end of the fist swing rod (51) is hinged with a first end of the second
swing rod (52) through a first pin (101) which forms a first hinge point (a), a first
end of the second connecting rod (54) is hinged at the middle of the second swing
rod (52), a second end of the first connecting rod (53) is hinged with a second end
of the second connecting rod (54) through a second pin (102) which forms a second
hinge point (b).
[0026] Furthermore, the linkage mechanism (5) also includes an elastic resetting mechanism
which makes the first hinge point (a) and the second hinge point (b) keep apart with
each other all along. The linkage mechanism (5) is composed of a spring seat (55),
a frame (56) and a helical compression spring (57). The main part of the spring seat
(55) is in conversed U-shape, a positioning sleeve (551) is provided on the top of
the main body of the spring seat (55) for the spring (57) to surround, a guiding column
(554) is inserted in the positioning sleeve (551) which can slide up and down relatively
to the positioning sleeve (551), the upper portion of the guiding column (554) is
fixed with the frame (56), the two side walls of the main body of the spring seat
(55) are respectively provided with a lengthways guiding hole (552), and the bottom
ends of the two side walls are respectively provided with a first hinging holes (553);
the first hinge point (a) and the second hinge point (b) are both disposed on the
two side walls of the main body of the spring seat (55), and journals of the two ends
of the first pin (101) are respectively rested in the corresponding first hinging
hole (553), the two ends of the second pin (102) are respectively disposed through
the corresponding lengthways guiding hole (552) and the second pin (102) can slide
lengthways along the lengthways guiding hole (552).
[0027] The frame (56) is disposed above the main body of the spring seat (55) and designed
to be conversed U-shaped, the bottom ends of the two side walls of the frame (56)
are respectively provided with a second hinging holes (561), the frame (56) can keep
linkage with the first connecting rod (53) and the second connecting rod (54) through
the second pin (102), the spring (57) is limited between the frame (56) and the main
body of the spring seat (55). The top of the frame (56) has a through hole (562) for
the upper portion of the guiding column (554) to go through, and the top of the guiding
column (554) which is above the top of the frame (56) is threaded connected with a
first nut (563), the portion of the guiding column (554) which is below the top of
the frame (56) is threaded connected with a second nut (564), the first nut (563)
and the second nut (564) make the upper portion of the guiding column (554) be limited
in the through hole (562) of the frame (56), so that the guiding column (554) can
connect with the frame(56).
[0028] A rocking rod crank mechanism is provided at the two sides of a linkage mechanism
(5), which can deliver the expansion of the linkage mechanism (5) to the adjusting
wheel which can change the size of wrap angle of the chain. The rocking rod crank
mechanism includes a first rocking rod (61), a second rocking rod (62), the first
pulling rod (71), the second pulling rod (72), the first linkage crank (81) and the
second linkage crank (82), as shown in Fig.1, Fig.2, Fig.3 and Fig.4.
[0029] The first rocking rod (61) is hinged on a second end (511) of the first swing rod
(51) through a pin (613) fixed at the bottom of the first rocking rod (61), the upper
portion of the first rocking rod (61) as the first end of the first rocking rod is
hinged on the lifting body (1) through a third pin (103), the bottom of the first
rocking rod (61) as the second end of the first rocking rod is provided with a first
fixing shaft (611) and disposed at the bottom of the first rocking rod (61), the first
tension wheel (33) surrounds the first fixing shaft (611).
[0030] A first adjusting wheel (91) is fixed on the first linkage crank (81), which is for
adjusting the wrap angle of the loose edge of the first chain (34) on the first traction
wheel (32). The middle of the first linkage crank (81) is hinged on the lifting body
(1), the second end of the first linkage crank (81) is hinged on the first end of
the first pulling rod (71), the second end of the first pulling rod (71) is hinged
on the first rocking rod (61) through the pin (614) at the bottom of the first rocking
rod (61).
[0031] The second rocking rod (62) includes a main portion (621) which is parallel to the
lifting body (1), a L-shaped bending portion (622) located above the main portion
(621) and bending toward the lifting body (1), and a second fixing shaft (623) which
is vertically disposed on the vertical wall of the L-shaped bending portion (622),
on which the second tension wheel (43) surrounds, and the second end (521) of the
second swing rod (52) is hinged on the second rocking rod (62) through the pin (625)
fixed above the second rocking rod (62).
[0032] A second adjusting wheel (92) is fixed on the second linkage crank (82), which is
for adjusting the wrap angle of the loose edge of the second chain (44) on the second
traction wheel (42). The middle of the second linkage crank (82) is hinged on the
lifting body (1), the second end of the second linkage crank (82) is hinged on the
first end of the second pulling rod (72), the second end of the second pulling rod
(72) is hinged on the second rocking rod (62).
[0033] In order to meet the double stroke protection requirement, the lifting body (1) is
fixed with two micro switches, i.e. a first safe switch (105) as a limit switch and
a second safe switch (106) as a check switch (the position of these two safe switches
can be replaceable).
[0034] The first safe switch (105) is located corresponding to the position of the second
rocking rod (62). When the lifting body (1) touches the ground, the second rocking
rod (62) can trigger the first safe switch (105) to control the motor (2) to stop,
the top of the main portion of the second rocking rod (62) is provided with a first
triggering block (624) which can press the first safe switch (105).
[0035] While, the second safe switch (106) is located corresponding to the position of the
first rocking rod (61), when the lifting body (1) touches the ground and the first
safe switch (105) fails to work, the first rocking rod (61) can trigger the second
safe switch (106) to control the motor (2) to stop, and the bottom of the first rocking
rod (61) is provided with a second triggering block (612) which can press the second
safe switch (106).
[0036] The working principle of the embodiment of the present invention is as below:
(1) At the status of the chain lifter in normal ascending and descending
[0037] When the lifter ascends, the motor (2) respectively drives the first driving wheel
(31) and the second driving wheel (41) to rotate clockwise; when the lifter descends,
the motor (2) respectively drives the first driving wheel (31) and the second driving
wheel (41) to rotate anticlockwise. Furthermore, during the normal ascending and descending
of the lifter, the chains on the first driving sprocket group and the second driving
sprocket group are respectively engaged to be N-shaped.
[0038] The first end of the first chain (34) moves round the bottom of the first traction
wheel (32) and is fixed on the top of the vertical guiding grooves (9). Due to the
gravity, whether the lifter ascends or descends, the chain at this side is in tight
state. The second end of the first chain (34) moves round the top edge of the first
traction wheel (32) and is fixed on the bottom of the vertical guiding grooves (9),
hanging on the first tension wheel (33) and the first driving wheel (31), whether
the lifter ascends or descends, the chain at this side is in loose state.
[0039] Likewise, the second chain (44) moves round the bottom of the second traction wheel
(42) and is fixed on the top of the vertical guiding grooves (9) with the chain at
this side in tight state, and the second chain (44) moves round the top edge of the
second traction wheel (42) and is fixed on the bottom of the vertical guiding grooves
(9) with the chain at this side in loose state.
[0040] Accordingly, under the pre-tightening force of the spring (57) of the linkage mechanism
(5), the first rocking rod (61) and the second rocking rod (62) keep partial to right,
as shown in Fig. 7, the first tension wheel (33) surrounding the first rocking rod
(61) is for tensioning the first chain (34), and the second tension wheel (43) surrounding
the second rocking rod (62) is for tensioning the second chain (44).
(2) At the status of the chain lifter in touching the ground
[0041] After the lifter descends and touches the ground, the motor (2) continues to drive
the first chain (34) and the second chain (44) to rotate anticlockwise owing to inertia,
the loose edge side of the originally first and second chain rotates to be in tight
state, the tight edge side of the originally first and second chain rotates to be
in loose state, i.e. the chain fixed on a first side of the vertical guiding grooves
(9) is in loose state.
[0042] As the motor keeps rotating, the first rocking rod (61) and the second rocking rod
(62) rotate anticlockwise under the pulling force of the first chain (34) and the
second chain (44), wherein the first triggering block (624) fixed on the second rocking
rod (61) conflicts with the first safe switch (105) first, and the first safe switch
(105) sends brake instructions to the brake module of the motor (2) through PLC after
the contact closes to control the motor to stop.
[0043] As the motor brake lags, the second chain (44) continues to pull the second rocking
rod (62) to rotate anticlockwise before the motor stops, as shown in Fig. 8, when
the second rocking rod (62) rotates anticlockwise, the second linkage crank (82) rotates
the same way under the action of the second pulling rod (72), and drives the second
adjusting wheel (92) to swing up, and then changes the wrap angle on the second traction
wheel (42) at the right side of the second chain (44), so as to reduce the looseness
of the loose edge side of the second chain (44).
[0044] Likewise, when the motor (2) continues to rotate, the first chain (34) forces the
first rocking rod (61) to rotate anticlockwise, pass the first pulling rod (71) and
cause the first linkage crank (81) to rotate clockwise, thus driving the first adjusting
wheel (91) to swing up, and then changing the wrap angle on the first traction wheel
(32) at the left side of the first chain (34), so as to reduce the looseness of the
loose edge side of the first chain (34).
[0045] In order to improve the safe operation of the equipment, the lifter is usually provided
with a double switch protection device, i.e. if the first safe switch (105) fails
to send the brake signal owing to some reason, the first rocking rod (61) and the
second rocking rod (62) continue to rotate anticlockwise under the traction force
of the chain, as shown in Fig. 9, the loose edge on the first chain (34) and the second
chain (44) is provided with more looseness; after the second triggering block (612)
fixed on the first rocking rod (61) touches the second safe switch (106), the contact
of the second safe switch (106) closes, and the second safe switch (106) sends fault
signal to the motor through PLC to control the motor to stop, before the motor completely
stops running, the first adjusting wheel (91) and the second adjusting wheel (92)
continue to swing up, which further reduces the wrap angle of the first traction wheel
(32) at the left side of the first chain (34) and the wrap angle of the second traction
wheel (42) at the right side of the second chain (44), and ensures the loose edge
of the first chain (34) and the second chain (44) to be kept at 20∼25mm (the chain
pitch in the embodiment is 31.75mm).
[0046] As the first rocking rod (61) and the second rocking rod (62) rotate anticlockwise
before the motor (2) stops, the first rocking rod (51) and the second rocking rod
(52) get closer, the second hinge point (b) slides along the lengthways guiding hole
(552) to approach the first hinge point (a), the spring (57) is in compression state,
the spring (57) in the embodiment is provided with the working stroke of around 30.4mm
from the initial pre-tightening state to the completely compressed state, 78mm of
descending stroke can be gained through the conversion of the chain operation length.
(3) At the status of the lifter upon touching the ground before ascending
[0047] When the lifter prepares to ascend, the motor drives the first chain and the second
chain to rotate clockwise, the chain at the loose side of the first chain and the
second chain gradually tightens, and the chain at the tight side of the first chain
and the second chain gradually loosens.
[0048] Accordingly, the first rocking rod (61) and the second rocking rod (62) rotate clockwise
under the restoring force of the spring (57), and drive the first linkage crank (81)
and the second linkage crank (82) to rotate clockwise, the first adjusting wheel (91)
and the second adjusting wheel (92) to swing down; as the chain is still provided
with certain looseness, the lifting body (1) of the lifter is still in touching the
ground state, when the first chain (34) and the second chain (44) fixed on the top
side of the vertical guiding grooves (9) is completely tightened, the lifting body
(1) begins to ascend away from the ground, at which moment the linkage mechanism is
recovered to the original state (i.e. the spring is in pre-tightening state, as shown
in Fig. 7), the traction force acted by the chain on the first rocking rod (61) and
the second rocking rod (62) is balanced with the pre-tightening force acted by the
spring (57) of the linkage mechanism (5) on the first rocking rod (61) and the second
rocking rod (62).
[0049] The chain lifer of the present invention automatically changes the wrap angle size
for the loose edge of the chain on the chain wheel through the linkage mechanism and
the rocking rod crank linkage mechanism, and further changes the looseness of the
loose edge of the chain and makes the looseness to be kept within a certain range,
it can prevent the chain from being too loose to lead to chain-disengaging or chain-sliding,
which makes the lifting body on the lifter have enough descending stroke during running
to the bottom of the vertical guiding grooves, and overcomes the defect of inability
to be adjusted appropriately for the tight and loose edge of the chain caused by the
lag of the motor brake, so as to ensure the work stability and reliability of the
lifter, the service life can be increased accordingly and the work efficiency of the
lifter being improved, in the same time, the chain wear and the maintenance cost being
reduced.
1. A chain lifer with safe descending stroke comprising:
a lifting body (1) which can move up and down along a pair of vertical guiding grooves
(9);
a motor (2) which is fixed on the middle of the lifting body (1);
a driving sprocket group, including a first driving wheel (31) and a second driving
wheel (41) both mounted on the output shaft of the motor (2), two first traction wheels
(32) respectively disposed at two sides of the output shaft of the motor (2), a first
tension wheel (33) disposed between one of the two first traction wheels (32) and
the first driving wheel (31), a first chain (34) engaged on the two first traction
wheels (32), the first tension wheel (33) and the first driving wheel (31), two second
traction wheels (42) respectively disposed at two sides of the output shaft of the
motor (2), a second tension wheel (43) disposed between one of the two second traction
wheels (42) and the second driving wheel (41) and located at the different side of
the first tension wheel (33) relatively to the output shaft of the motor (2), a second
chain (44) engaged on the two second traction wheels (42), the second tension wheel
(43) and the second driving wheel (41);
characterized in that the chain lifter also comprises:
a linkage mechanism (5) disposed between the first tension wheel (33) and the second
tension wheel (43), which includes a first swing rod (51), a second swing rod (52),
a first connecting rod (53) and a second connecting rod (54) all disposed substantially
in a same plane, a first end of the fist swing rod (51) is hinged with a first end
of the second swing rod (52) through a first pin (101) which forms a first hinge point
(a), a first end of the second connecting rod (54) is hinged at the middle of the
second swing rod (52), a second end of the first connecting rod (53) is hinged with
a second end of the second connecting rod (54) through a second pin (102) which forms
a second hinge point (b), furthermore, the linkage mechanism (5) also includes an
elastic resetting mechanism which makes the first hinge point (a) and the second hinge
point (b) keep apart with each other all along;
a first rocking rod (61), the first end of which is hinged on the lifting body (1),
the second end of which is provided with a first fixing shaft (611) on which the first
tension wheel (33) surround, and which the second end of the second swing rod (52)
is hinged on;
a second rocking rod (62), the first end of which is hinged on the lifting body (1),
the second end of which is provided with a second fixing shaft (623) on which the
second tension wheel (43) surround, and which the second end of the second swing rod
(52) is hinged on;
a first safe switch (105), fixed on the lifting body (1) and located corresponding
to the position of the second rocking rod (62), when the lifting body (1) touches
the ground, the second rocking rod (62) can trigger the first safe switch (105) to
control the motor (2) to stop;
a second safe switch (106), fixed on the lifting body (1) and located corresponding
to the position of the first rocking rod (61), when the lifting body (1) touches the
ground and the first safe switch (105) fails to work, the first rocking rod (61) can
trigger the second safe switch (106) to control the motor (2) to stop;
a first linkage crank (81); a first pulling rod (71); a second linkage crank (82);
a second pulling rod (72);
a first adjusting wheel (91) for adjusting the wrap angle of the loose edge of the
first chain (34) on the first traction wheel (32), the main shaft of the first adjusting
wheel (91) is fixed on the first end of the first linkage crank (81), the middle of
the first linkage crank (81) is hinged on the lifting body (1), the second end of
the first linkage crank (81) is hinged on the first end of the first pulling rod (71),
the second end of the first pulling rod (71) is hinged on the first rocking rod (61);
a second adjusting wheel (92) for adjusting the wrap angle of the loosen edge of the
second chain (44) on the second traction wheel (42), the main shaft of the second
adjusting wheel (92) is fixed on the first end of the second linkage crank (82), the
middle of the second linkage crank (82) is hinged on the lifting body (1), the second
end of the second linkage crank (82) is hinged on the first end of the second pulling
rod (72), the second end of the second pulling rod (72) is hinged on the second rocking
rod (62).
2. The chain lifter of claim 1, wherein the elastic resetting mechanism includes a spring
seat (55), a frame (56) and a spring (57), the spring seat (55) is in conversed U-shape,
a positioning sleeve (551) is provided on the top of the main body of the spring seat
(55) for the spring (57) to surround, a guiding column (554) is inserted in the positioning
sleeve (551) which can slide up and down relatively to the positioning sleeve (551),
the upper portion of the guiding column (554) is fixed with the frame(56), the two
side walls of the main body of the spring seat (55) are respectively provided with
a lengthways guiding hole (552), and the bottom ends of the two side walls are respectively
provided with a first hinging holes (553);
the first hinge point (a) and the second hinge point (b) are both disposed on the
two side walls of the main body of the spring seat (55), and journals of the two ends
of the first pin (101) are respectively rested in the corresponding first hinging
hole (553), the two ends of the second pin (102) are respectively disposed through
the corresponding lengthways guiding hole (552) and the second pin (102) can slide
lengthways along the lengthways guiding hole (552);
the frame (56) is disposed above the main body of the spring seat (55), the frame
(56) can keep linkage with the first connecting rod (53) and the second connecting
rod (54) through the second pin (102), the spring (57) is limited between the frame
(56) and the main body of the spring seat (55) to make the frame (56) keep apart with
the spring seat (55) all along.
3. The chain lifter of claim 2, wherein the frame (56) is designed to be conversed U-shaped,
the bottom ends of the two side walls of the frame (56) are respectively provided
with a second hinging holes (561), journals of the two ends of the second pin (102)
are respectively rested in the corresponding second hinging holes (561);
the upper portion of the guiding column (554) has threads outside, the top of the
frame (56) has a through hole (562) for the upper portion of the guiding column (554)
to go through, and the top of the guiding column (554) which is above the top of the
frame (56) is threaded connected with a first nut (563), the portion of the guiding
column (554) which is below the top of the frame (56) is threaded connected with a
second nut (564), the first nut (563) and the second nut (564) make the upper portion
of the guiding column (554) be limited in the through hole (562) of the frame (56).
4. The chain lifter of claim 1 or claim 2 or claim 3, wherein the first safe switch (105)
is a micro switch, the second rocking rod (62) includes a main portion (621) which
is parallel to the lifting body (1), a L-shaped bending portion (622) located above
the main portion (621) and bending toward the lifting body (1), and a second fixing
shaft (623) which is vertically disposed on the vertical wall of the L-shaped bending
portion (622), the bottom of the main portion (621) is the first end of the second
rocking rod (62) which is hinged on the lifting body (1) through a fourth pin (104),
the top of the main portion (621) is provided with a first triggering block (624)
which can press the first safe switch (105).
5. The chain lifter of claim 1 or claim 2 or claim 3, wherein the second safe switch
(106) is a micro switch, the top of the first rocking rod (61) is the first end of
the first rocking rod (61) which is hinged on the lifting body (1) through a third
pin (103), a first fixing shaft (611) is disposed at the bottom of the first rocking
rod (61), and the bottom of the first rocking rod (61) is provided with a second triggering
block (612) which can press the second safe switch (106).