U.S. patent application number 16/351354 was filed with the patent office on 2020-09-17 for linear transmission device.
This patent application is currently assigned to HIWIN TECHNOLOGIES CORP.. The applicant listed for this patent is HIWIN TECHNOLOGIES CORP.. Invention is credited to Wei-Lun LIU, Shang-Hua TSAI.
Application Number | 20200292038 16/351354 |
Document ID | / |
Family ID | 1000005059781 |
Filed Date | 2020-09-17 |
United States Patent
Application |
20200292038 |
Kind Code |
A1 |
LIU; Wei-Lun ; et
al. |
September 17, 2020 |
Linear Transmission Device
Abstract
A linear transmission device includes: an elongated shaft
member, a moving module, a rolling unit, a return assembly, a
sensor and a data receiving unit. The linear transmission device
has a simple structure. The sensor is disposed at the junction of
the first return pipe and the second return pipe of the return
assembly to timely detect the change in the distance between the
rolling elements, which can determine whether there is an
abnormality in the shape of the spacers. With the sensor outputting
detecting signals, it can stop the terminal immediately to confirm
the condition of the workpieces and the machine, avoiding the
structural damage of the machine and the workpiece caused by the
continuous operation. The sensor can also serve as a medium for
transferring data, further facilitating maintenance.
Inventors: |
LIU; Wei-Lun; (Taichung
City, TW) ; TSAI; Shang-Hua; (Taichung City,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HIWIN TECHNOLOGIES CORP. |
Taichung City |
|
TW |
|
|
Assignee: |
HIWIN TECHNOLOGIES CORP.
|
Family ID: |
1000005059781 |
Appl. No.: |
16/351354 |
Filed: |
March 12, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16H 25/2015 20130101;
F16H 25/2219 20130101 |
International
Class: |
F16H 25/22 20060101
F16H025/22; F16H 25/20 20060101 F16H025/20 |
Claims
1. A linear transmission device comprising: an elongated shaft
member extending along an axial direction and having a helical
groove; a moving module movably sleeved onto the elongated shaft
member and reciprocally displaceable along the axial direction, and
having a rolling groove which is aligned with the helical groove to
form a load path; a rolling unit disposed in the load path and
having a plurality of rolling elements and a plurality of spacers,
there is one said spacer between each two neighboring said rolling
elements; a return assembly inserted in the moving module and in
communication with the load path, having a first return pipe, a
second return pipe communicating with the first return pipe, and a
return passage which extends through the first return pipe and the
second return pipe and is provided for the rolling unit to
circulate; at least one sensor disposed on the moving module and
located at a joint between the first return pipe and the second
return pipe, when the rolling unit moves in the return passage, the
at least one sensor is able to detect the change of a distance
between the rolling elements and output a detecting signal; and a
data receiving unit signal connected to the at least one sensor for
receiving the detecting signal from the at least one sensor.
2. The linear transmission device as claimed in claim 1, wherein
the linear transmission device is a ball screw or a linear
guideway.
3. The linear transmission device as claimed in claim 1, wherein
the linear transmission device is a ball screw and further
comprises a fixing cover disposed on an outer surface of the moving
module to cover the return assembly and the at least one sensor,
the fixing cover has a receiving groove for receiving the return
assembly, and at least one recess recessed in an inner surface of
the receiving groove to accommodate the at least one sensor.
4. The linear transmission device as claimed in claim 1, wherein
the sensor is wirelessly connected to the data receiving unit to
achieve signal transmission.
5. The linear transmission device as claimed in claim 1, wherein
the sensor is an inductance type sensor or a light inductive type
sensor.
6. The linear transmission device as claimed in claim 1, wherein
the first return pipe has a first connecting end and a first return
end, the second return pipe has a second connecting end and a
second return end, the return passage extends through the first
connecting end and the first return end of the first return pipe,
and the second connecting end and the second return end of the
second return pipe, the first connecting end of the first return
pipe corresponds to the second connecting end of the second return
pipe, the first return end of the first return pipe and the second
return end of the second return pipe are connected to two ends of
the load path, respectively, the at least one sensor is disposed at
one side of the first connecting end of the first return pipe and
the second connecting end of the second return pipe.
7. The linear transmission device as claimed in claim 6, wherein
the first connecting end of the first return pipe abuts against the
second connecting end of the second return pipe.
8. The linear transmission device as claimed in claim 6, wherein
the first connecting end of the first return pipe is spaced apart
from the second connecting end of the second return pipe by 0.1 mm
to 0.2 mm.
9. The linear transmission device as claimed in claim 6, wherein a
part of the return passage that extends through the first
connecting end and the second connecting end is straight
linear.
10. The linear transmission device as claimed in claim 1, wherein
the return assembly is made of plastic.
Description
BACKGROUND
Field of the Invention
[0001] The present invention relates to a linear transmission
device, and more particularly to a linear transmission device which
can directly detect the change in the distance between the rolling
elements.
Related Prior Art
[0002] Referring to FIG. 1A, which is a drawing of a linear roller
bearing of the related art (U.S. Pat. No. 7,178,981 B2) having a
guide carriage 1 which can be mounted on a guide rail 2 in a
rolling manner via balls (not shown). The guide carriage 1 is
provided with at least one rolling passage (not shown) for the
balls, the rolling passage includes a support passage (not shown)
for supporting the balls, and a deflecting channel (not shown) that
is disposed in the end elements 3 of the guide carriage 1. The
balls in the rolling passage are subjected to displacement
resistance in the direction of rotation. The end elements 3 are
respectively provided with a sensor 4 for detecting the
displacement resistance caused by the deformation of the cover
plate during the displacement of the balls, so as to determine
whether there is abnormality. However, the installation of the
above-described sensor 4 generally increases the length of the
guide carriage 1, which in turn increases the cost and complexity
of the structure, which will affect the travel length.
[0003] Please refer to FIG. 1B, which is one of the drawings of the
Japanese patent (JP2007225024) showing a ball screw with a sensing
device, wherein the sensing device 6 is provided in a recess of a
nut 5 (capacitive type, optical type)) for measuring the
displacement of the balls 7, and then determining the stress
condition of the nut 5. However, the structure of the sensing
device 6 changes the size of the nut 5, so that the outer diameter
of the nut 5 is increased, which in turn affects the travel length
of the nut 5.
[0004] Referring then to Japanese Patent No. JP3936519, which
discloses a technical content in which a vibration sensor is
provided at a bend of an outer circulation member of a ball screw
to detect the running condition of the balls, wherein special
boring processing has to be performed on the nut to install the
vibration sensor, and the boring processing is complicated and the
cost is higher. Moreover, installing the vibration sensor at the
bend of the outer circulation member, can only detect the stress
change caused by the ball striking the wall surface at the bend of
the outer circulation member to know the running condition of the
balls (for example, insufficient lubrication may cause the ball to
run unsmoothly), it is impossible to measure the change in the
distance between the balls, and it is impossible to know whether
the balls are jammed or not.
[0005] The remaining patents, such as Japanese Patent Nos
JPA2014159847 and JPA2013200032, all have the above-mentioned
disadvantages. Therefore, there is still room for improvement in
the conventional linear transmission devices.
SUMMARY
[0006] One objective of the present invention is to provide a
linear transmission device which can directly detect the change in
the distance between the rolling elements, and further know whether
the spacers between the rolling elements are collapsed or jammed,
thus avoiding the shutdown of the machine caused by the damage to
the linear transmission device.
[0007] To achieve the above objective, a linear transmission device
in accordance with the present invention comprises:
[0008] an elongated shaft member extending along an axial direction
and having a helical groove;
[0009] a moving module movably sleeved onto the elongated shaft
member and reciprocally displaceable along the axial direction, and
having a rolling groove which is aligned with the helical groove to
form a load path;
[0010] a rolling unit disposed in the load path and having a
plurality of rolling elements and a plurality of spacers, there is
one said spacer between each two neighboring said rolling
elements;
[0011] a return assembly inserted in the moving module and in
communication with the load path, having a first return pipe, a
second return pipe communicating with the first return pipe, and a
return passage which extends through the first return pipe and the
second return pipe and is provided for the rolling unit to
circulate;
[0012] at least one sensor disposed on the moving module and
located at a joint between the first return pipe and the second
return pipe, when the rolling unit moves in the return passage, the
at least one sensor is able to detect the change of a distance
between the rolling elements and output a detecting signal; and
[0013] a data receiving unit signal connected to the at least one
sensor for receiving the detecting signal from the at least one
sensor.
[0014] Preferably, the linear transmission device is a ball screw
or a linear guideway.
[0015] Preferably, the linear transmission device is a ball screw
and further comprises a fixing cover disposed on an outer surface
of the moving module to cover the return assembly and the at least
one sensor, the fixing cover has a receiving groove for receiving
the return assembly, and at least one recess recessed in an inner
surface of the receiving groove to accommodate the at least one
sensor.
[0016] Preferably, the sensor is wirelessly connected to the data
receiving unit to achieve signal transmission.
[0017] Preferably, the sensor is an inductance type sensor or a
light inductive type sensor.
[0018] Preferably, the first return pipe has a first connecting end
and a first return end, the second return pipe has a second
connecting end and a second return end, the return passage extends
through the first connecting end and the first return end of the
first return pipe, and the second connecting end and the second
return end of the second return pipe, the first connecting end of
the first return pipe is connected to the second connecting end of
the second return pipe, the first return end of the first return
pipe and the second return end of the second return pipe are
connected to two ends of the load path, respectively, the at least
one sensor is disposed at one side of the first connecting end of
the first return pipe and the second connecting end of the second
return pipe.
[0019] Preferably, the first connecting end of the first return
pipe abuts against the second connecting end of the second return
pipe.
[0020] Preferably, the first connecting end of the first return
pipe is spaced apart from the second connecting end of the second
return pipe by 0.1 mm to 0.2 mm.
[0021] Preferably, a part of the return passage that extends
through the first connecting end and the second connecting end is
straight linear.
[0022] Preferably, the return assembly is made of plastic.
[0023] The invention provides a linear transmission device
consisting of the elongated shaft member, the moving module, the
rolling unit, the return assembly, the sensor and the data
receiving unit. Therefore, the present invention has a simple
structure. The sensors are disposed at the junction of the first
return pipe and the second return pipe of each of the return
assemblies to timely detect the change in the distance between the
rolling elements, which can determine whether there is an
abnormality in the shape of the spacers. With the sensors
outputting detecting signals, it can stop the terminal immediately
to confirm the condition of the workpieces and the machine,
avoiding the structural damage of the machine and the workpiece
caused by the continuous operation. The sensors can also serve as a
medium for transferring data, further facilitating maintenance.
[0024] These together with other objects of the invention, along
with the various features of novelty which characterize the
invention, are pointed out with particularity in the claims annexed
to and forming a part of this disclosure. For a better
understanding of the invention, its operating advantages and the
specific objects attained by its uses, reference should be had to
the accompanying drawings and descriptive matter in which there are
illustrated preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1A is one of the drawings of a linear roller bearing of
the U.S. Pat. No. 7,178,981 B2;
[0026] FIG. 1B is one of the drawings of a ball screw with a
sensing device of Japanese Patent (JP2007225024);
[0027] FIG. 2 is a perspective view of a first embodiment of the
present invention showing the linear transmission device as a ball
screw;
[0028] FIG. 3A is an exploded view (1) of the first embodiment of
the present invention;
[0029] FIG. 3B is an exploded view (2) of the first embodiment of
the present invention;
[0030] FIG. 4 is a cross-sectional view (1) of the first embodiment
of the present invention;
[0031] FIG. 5 is a cross-sectional view (2) of the first embodiment
of the present invention;
[0032] FIG. 6 is a perspective view of a second embodiment of the
present invention, showing that the sensor and the data receiving
unit are wirelessly connected for signal transmission; and
[0033] FIG. 7 is a perspective view of a third embodiment of the
present invention showing the linear transmission device as a
linear guideway.
DETAILED DESCRIPTION
[0034] The present invention will be clearer from the following
description when viewed together with the accompanying drawings,
which show, for purpose of illustrations only, the preferred
embodiment in accordance with the present invention.
[0035] Referring to FIGS. 2-5, a linear transmission device in
accordance with a preferred embodiment of the present invention is
shown, the linear transmission device is exemplified by a ball
screw, but is not limited thereto, or is a linear guideway as shown
in FIG. 7, wherein the linear transmission device comprises: an
elongated shaft member 20, a moving module 30, a rolling unit 40,
two return assemblies 50, four sensors 60, a fixing cover 70, a
data receiving unit 80.
[0036] The elongated shaft member 20 extends along an axial
direction X. The elongated shaft member 20 of the embodiment is a
screw, and has a screw annular surface 21 and a helical groove 22
formed in the screw annular surface 21.
[0037] The moving module 30 is movably sleeved onto the elongated
shaft member 20 and reciprocally displaceable along the axial
direction X, and has a rolling groove 31 which is aligned with the
helical groove 22 to form a load path. The moving module 30 of the
embodiment is a nut.
[0038] The rolling unit 40 is disposed in the load path and has a
plurality of rolling elements 41 and a plurality of spacers 42.
There is one spacer 42 between each two rolling elements 41. In
this embodiment, the rolling elements 41 are balls. In other
embodiments, the rolling elements 41 can be rollers; the spacers 42
are cylindrical, and a groove for accommodating a part of the
rolling elements 41 is recessed on both sides of the spacer 42
respectively.
[0039] The two return assemblies 50 are made of plastic material.
The two return assemblies 50 are disposed on an outer surface of
the moving module 30 and communicate with the load path. In this
embodiment, each of the return assemblies 50 has two ends inserted
in the moving module 30, and includes a first return pipe 51, a
second return pipe 52 communicating with the first return pipe 51,
and a return passage 53 which extends through the first return pipe
51 and the second return pipe 52 and is provided for the rolling
unit 40 to circulate.
[0040] In this embodiment, the two return assemblies 50 are
substantially identical in structure, and thus only one of the
return assemblies 50 is further described. The first return pipe 51
has a first connecting end 512 and a first return end 514. The
second return pipe 52 has a second connecting end 522 and a second
return end 524. The return passage 53 extends through the first
connecting end 512 and the first return end 514 of the first return
pipe 51, and the second connecting end 522 and the second return
end 524 of the second return pipe 52. The part of the return
passage 53 that extends through the first connecting end 512 and
the second connecting end 522 is straight linear. The first
connecting end 512 of the first return pipe 51 corresponds to the
second connecting end 522 of the second return pipe 52. In this
embodiment, the first connecting end 512 of the first return pipe
51 is abutted against the second connecting end 522 of the second
return pipe 52, but are not limited thereto, the first connecting
end 512 of the first return pipe 51 and the second connecting end
522 of the second return pipe 52 can also be separated from each
other by a small gap, that is, they do not contact each other. The
first return end 514 of the first return pipe 51 and the second
return end 524 of the second return pipe 52 are connected to two
ends of the load path, respectively.
[0041] In other embodiments, the linear transmission device may
also have only one return assembly 50.
[0042] The elongated shaft member (screw), the moving module (nut),
the two return assemblies, and the rolling unit are assembled and
operated in a conventional way, and this is not the focus of this
invention. Therefore, the detailed structure, assembly method and
operation of the components (the long shaft member, the moving
module, the two return assemblies, and the rolling unit) are not
described in detail.
[0043] The four sensors 60 are disposed in pairs on opposite sides
of the outer surface of the return assemblies 50, and located at
the joint between the first return pipe 51 and the second return
pipe 52 of each of the return assemblies 50, and more specifically,
the four sensors 60 are respectively located in pairs on opposite
sides of a position where the first connecting end 512 of the first
return pipe 51 and the second connecting end 522 of the second
return pipe 52 are connected. Of course, this is not a limitation.
Referring to FIG. 3B, in another preferred embodiment, there can
also be only one sensor 60 disposed at one side at a position where
the first connecting end 512 of the first return pipe 51 and the
second connecting end 522 of the second return pipe 52 are
connected, and it can also achieve the same effect. When the
rolling unit 40 moves in the return passage 53, each of the sensors
60 can detect the change of the distance between the rolling
elements 41 and output a detecting signal to determine whether gaps
between each two adjacent rolling elements 41 are different from
each other to determine whether each of the spacers 42 between the
rolling elements 41 is damaged or falls and laterally disposed.
Besides, since the part of the return passage 53 that extends
through the first connecting end 512 and the second connecting end
522 is straight linear, each of the rolling elements 41 and the
spacers 42 will move in a substantially linear manner through the
part of the return passage 53 that extends through the first
connecting end 512 and the second connecting end 522, so that the
detecting signal detected by the sensors 60 are relatively
accurate. In this embodiment, the sensors 60 are exemplified by
inductance type, but are not limited thereto, or can also be light
inductive type. The inductance type is a device that realizes
measurement by utilizing the change of self-inductance or mutual
inductance of the coil, which has the advantages of low structural
cost, customizable external dimensions, large output power, strong
anti-interference ability, low requirements on the working
environment, high resolution and good stability. The light
inductive sensor utilizes various properties of light to detect the
presence or absence of an object or a change in surface state,
etc., and has the advantages of long detection distance, less
restriction conditions for detecting an object, completing
detection in a non-contact manner, and higher resolution. When the
spacer 42 located between the two rolling elements 41 is displaced
and tilted to cause the distance between the two rolling elements
41 to exceed the safety value (the safety value is 2 mm in this
embodiment, which is not limited thereto in other embodiments, and
may vary for different design purposes), it is highly probable that
the rolling unit 40 in the return passage 53 and the load path will
be jammed to cause equipment damage and shutdown. Through the
design of the sensors 60, it is possible to timely diagnose the
abnormality of the linear transmission device, and let the terminal
immediately stop to confirm the condition of the workpieces and the
machine, avoiding the structural damage of the machine and the
workpiece caused by the continuous operation.
[0044] It is to be noted that, in this embodiment, the first
connecting end 512 of the first return pipe 51 abuts against the
second connecting end 522 of the second return pipe 52. In other
preferred embodiments, the first connecting end 512 of the first
return pipe 51 is spaced apart from the second connecting end 522
of the second return pipe 52 by 0.1 mm to 0.2 mm, so that the
sensors 60 can measure the change of the distance between the
rolling elements 41 by the gap between the first connecting end 512
and the second connecting end 522 to improve the precision and
effect of the sensing.
[0045] A fixing cover 70 is disposed on the outer surface of the
moving module 30 to cover the two return assemblies 50 and the four
sensors 60, and has a receiving groove 71 for receiving the return
assemblies 50, and four recesses 72 recessed from an inner surface
of the receiving groove 71 to accommodate the four sensors 60.
[0046] Specifically, most of the conventional monitoring methods
use an adhesive accelerometer to monitor the operation of the ball
screw, but often face the problem of where the sensing component is
placed and whether the signal strength is sufficient. Therefore,
the present invention improves the above defects. The inner surface
of the receiving groove 71 is recessed with four recesses 72 to
accommodate the four sensors 60. In addition to the fact that the
four sensors 60 can be fixed, the sensors 60 can be brought closer
to the two return assemblies 50, thereby effectively reducing
signal interference to maintain stable signal.
[0047] Therefore, the present invention fully utilizes the original
space of the fixing cover 70 to accommodate the four sensors 60, so
that not only the size of the original shape of the elongated shaft
member 20 is not changed, but also the design of the original
machine is not affected, as a result, the change of distance
between each two neighboring rolling elements 41 is instantly
detected, thereby avoiding shutdown of the machine.
[0048] The data receiving unit 80 is signal connected to the four
sensors 60 for receiving the detecting signal from the four sensors
60. This embodiment is a wired transmission as an example, but is
not limited thereto, as shown in FIG. 6, the four sensors 60 is
wirelessly connected to the data receiving unit 80 via Wi-Fi,
Bluetooth, RF, ZigBee, LoRa, WiGig, 4G or 5G to achieve signal
transmission, thereby eliminating the cumbersome physical wiring
project and the space of wiring, without considering the
installation wiring.
[0049] In addition, the above embodiment is described by using a
ball screw as an example. Referring to FIGS. 2 and 7, the linear
transmission device of the embodiment can also be applied to a
linear guideway, so that the elongated shaft member 20 is a rail,
the moving module 30 is a slider, and the two return assemblies 50
are disposed in the moving module 30. When a chain holder 90 is
broken, the gaps between the rolling elements 91 at the break are
increased. The sensors 60 can detect the abnormal shape of the
chain holder 90, which can also achieve the same effect as
described above.
[0050] The above description is the configuration description of
each main component of the embodiment of the present invention. The
effects and functions of the present invention are explained
below.
[0051] Therefore, the present invention has a simple structure. The
sensors 60 are disposed at the junction of the first return pipe 51
and the second return pipe 52 of each of the return assemblies 50
to timely detect the change in the distance between the rolling
elements 41, which can determine whether there is an abnormality in
the shape of the spacers 42. With the sensors 60 outputting
detecting signals, it can stop the terminal immediately to confirm
the condition of the workpieces and the machine, avoiding the
structural damage of the machine and the workpiece caused by the
sensors 60 can also serve as a medium for transferring data,
further facilitating maintenance.
[0052] While we have shown and described various embodiments in
accordance with the present invention, it is clear to those skilled
in the art that further embodiments may be made without departing
from the scope of the present invention.
* * * * *