U.S. patent application number 14/348686 was filed with the patent office on 2014-08-28 for control system for operating work device for construction machine.
This patent application is currently assigned to VOLVO CONSTRUCTION EQUIPMENT AB. The applicant listed for this patent is Hea-Gyoon Joung, Young-Bog Song. Invention is credited to Hea-Gyoon Joung, Young-Bog Song.
Application Number | 20140238010 14/348686 |
Document ID | / |
Family ID | 48043892 |
Filed Date | 2014-08-28 |
United States Patent
Application |
20140238010 |
Kind Code |
A1 |
Joung; Hea-Gyoon ; et
al. |
August 28, 2014 |
CONTROL SYSTEM FOR OPERATING WORK DEVICE FOR CONSTRUCTION
MACHINE
Abstract
Disclosed is a control system for controlling flow so as to
allow simultaneous usage of a parallel flow path and a tandem flow
path thereby reducing loss of pressure inside a control valve, when
simultaneously operating work devices having different operating
pressures. A control system for operating the work device,
according to the present invention, provides the control system for
operating the work device for a construction machine, comprising:
first and second hydraulic pumps that are connected to an engine; a
revolution control valve, an arm control valve, and a left driving
control valve, which are installed on a first center bypass path of
the first hydraulic pump, and each of which is connected via the
parallel flow path; a boom control valve, a bucket control valve,
and a right driving valve, which are installed on a second center
bypass path of the second hydraulic pump, and each of which is
connected via the parallel flow path; a pressure generation device;
a bleed flow path, which is formed on a control spool at a lower
side of a boom of the boom control valve, for maintaining an open
state of the second center bypass path without closing same, when
the boom control valve is switched so as to lower the boom; and a
center bypass switch valve, which is installed on the lowermost
side of the second center bypass path and is switched by means of a
control signal for switching the boom control valve.
Inventors: |
Joung; Hea-Gyoon; (Busan,
KR) ; Song; Young-Bog; (Changwon-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Joung; Hea-Gyoon
Song; Young-Bog |
Busan
Changwon-si |
|
KR
KR |
|
|
Assignee: |
VOLVO CONSTRUCTION EQUIPMENT
AB
Eskilstuna
SE
|
Family ID: |
48043892 |
Appl. No.: |
14/348686 |
Filed: |
October 7, 2011 |
PCT Filed: |
October 7, 2011 |
PCT NO: |
PCT/KR2011/007439 |
371 Date: |
March 31, 2014 |
Current U.S.
Class: |
60/428 |
Current CPC
Class: |
E02F 3/42 20130101; F15B
2211/3133 20130101; E02F 9/22 20130101; E02F 9/2267 20130101; F15B
11/17 20130101; F15B 2211/3116 20130101; E02F 9/2282 20130101; E02F
9/2292 20130101; E02F 9/2285 20130101; F15B 2211/20576 20130101;
E02F 9/123 20130101; E02F 9/2217 20130101; F15B 2211/20546
20130101; E02F 9/2225 20130101 |
Class at
Publication: |
60/428 |
International
Class: |
E02F 9/22 20060101
E02F009/22; E02F 9/12 20060101 E02F009/12; E02F 3/42 20060101
E02F003/42 |
Claims
1. An attachment driving control system for a construction machine,
comprising: an engine; first and second variable displacement
hydraulic pumps connected to the engine and a pilot pump; a swing
control valve configured to control the drive of a swing motor, an
arm control valve configured to control the drive of an arm
cylinder, and a traveling control valve configured to control the
drive of a left traveling motor wherein the swing control valve,
the arm control valve, and the traveling control valve are
installed in a first center bypass path of the first hydraulic pump
so as to be connected to a parallel flow path, respectively; a boom
control valve configured to control the drive of a boom cylinder, a
bucket control valve configured to control the drive of a bucket
cylinder, and a traveling control valve configured to control the
drive of a right traveling motor wherein the boom control valve,
the bucket control valve, and the traveling control valve are
installed in a second center bypass path of the second hydraulic
pump so as to be connected to a parallel flow path, respectively;
pressure generation devices configured to output a control signal
corresponding to a manipulation amount; a bleed flow path formed on
a control spool on a boom descending side of the boom control valve
and configured to maintain the second center bypass path in an
opened state instead of blocking the second center bypass path when
the boom control valve is shifted to descend the boom through the
manipulation of the pressure generation device; and a center bypass
shift valve installed on a lowermost downstream side of the second
center bypass path and configured to be shifted by a control signal
pressure for shifting the boom control valve, wherein a hydraulic
fluid from the second hydraulic pump flows into the bucket control
valve through the parallel flow path and a tandem flow path
connected to the second center bypass path when a boom for
performing a boom descending operation and an attachment requiring
an operating pressure relatively higher than that of the boom are
simultaneously driven.
2. The attachment driving control system according to claim 1,
wherein the attachment is a bucket, and the control valve that
controls the attachment is the bucket control valve.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an attachment driving
control system for a construction machine. More particularly, the
present invention relates to an attachment driving control system
for a construction machine, in which in the case where two
attachments having different operating pressures are simultaneously
driven (e.g., the case where a boom for performing a boom
descending operation and an attachment such as a bucket are
simultaneously driven), a flow rate of a hydraulic fluid is
controlled to enable the simultaneous use of a parallel flow path
and a tandem flow path, leading to a reduction in a pressure loss
occurring in the control valve.
BACKGROUND OF THE INVENTION
[0002] In general, a conventional boom driving control system for a
construction machine in accordance with the prior art as shown in
FIG. 1 includes:
[0003] an engine 1;
[0004] first and second variable displacement hydraulic pumps
(hereinafter, referred to as "first and second hydraulic pumps") 2
and 3 that are connected to the engine 1 and a pilot pump 4;
[0005] a swing control valve 7 that controls the drive of a swing
motor 6, an arm control valve 9 that controls the drive of an arm
cylinder 8, and a traveling control valve 11 that controls the
drive of a left traveling motor 10 wherein the swing control valve,
the arm control valve, and the traveling control valve are
installed in a first center bypass path 5 of the first hydraulic
pump 2 so as to be connected to a parallel flow path 5a,
respectively;
[0006] a boom control valve 14a that controls the drive of a boom
cylinder 13, a bucket control valve 16 that controls the drive of a
bucket cylinder 15, and a traveling control valve 18 that controls
the drive of a right traveling motor 17 wherein the boom control
valve, the bucket control valve, and the traveling control valve
are installed in a second center bypass path 12 of the second
hydraulic pump 3 and 2 so as to be connected to a parallel flow
path 12a, respectively; and
[0007] pressure generation devices 19 and 20 that outputs a control
signal corresponding to a manipulation amount.
[0008] When the pressure generation device 19 is in a neutral
position, a hydraulic fluid discharged from the second hydraulic
pump 3 returns to a hydraulic tank T through the second center
bypass path 12 and the return flow path 21.
[0009] In the case where the pressure generation device 19 is
manipulated to ascend a boom, a pilot signal pressure from a pilot
pump 4 is supplied to the boom control valve 14 via the pressure
generation device 19. For this reason, the boom control valve 14 is
shifted to the left on the drawing sheet to cause the boom to
ascend, and thus the hydraulic fluid discharged from the second
hydraulic pump 3 is supplied to a large chamber of the boom
cylinder 13 via a load check valve 22 and the boom control valve
14. At this same time, a hydraulic fluid flowing out of a small
chamber of the boom cylinder 13 returns to the hydraulic tank T via
the boom control valve 14. Thus, the boom cylinder 13 can be driven
in a stretchable manner to cause the boom to ascend.
[0010] In the meantime, in the case where the pressure generation
device 19 is manipulated to descend the boom, the pilot signal
pressure from the pilot pump 4 is supplied to the boom control
valve 14 via the pressure generation device 19.
[0011] For this reason, the boom control valve 14 is shifted to the
right on the drawing sheet to cause the boom to descend, and thus
the hydraulic fluid discharged from the second hydraulic pump 3 is
supplied to the small chamber of the boom cylinder 13 via the boom
control valve 14. At this same time, the hydraulic fluid flowing
out of the large chamber of the boom cylinder 13 returns to the
hydraulic tank T via the boom control valve 14 and a back pressure
check valve 23. Thus, the boom cylinder 13 can be driven in a
retractable manner to cause the boom to descend.
[0012] In this case, the back pressure check valve 23 is mounted
with a valve spring so that when a hydraulic fluid passes
therethrough, a constant pressure is formed. In addition, a
regeneration line is installed in the back pressure check valve 23
so that the hydraulic fluid flowing out of the large chamber of the
boom cylinder 13 can be regenerated to the small chamber of boom
cylinder 13 along the regeneration line during the descending of
the boom.
[0013] As described above, when the boom descends, a lower pressure
acts on the boom due to the descending operation by its own weight.
Meantime, in the case where a boom for performing a boom descending
operation and an attachment (e.g., referring to bucket) requiring
having an operating pressure relatively higher than that of the
boom are simultaneously driven, a throttle device is installed at a
hydraulic fluid inlet side of a control spool (i.e., referring to
the boom control valve 14) on a boom descending side so that
simultaneous manipulability of the boom and the bucket can be
maintained.
[0014] In the meantime, a throttle device is installed in the
parallel flow path of each attachment that is operated at a
relatively low pressure to produce a pressure causing the boom to
ascend so that simultaneous manipulability of the boom for
performing a boom ascending operation and another attachment can be
implemented.
[0015] Besides, a tandem flow path is formed in the bucket control
valve 16 and the traveling control valve 18 which are connected in
parallel with the boom control valve 14 through the second center
bypass path 12. That is, in the case where the drive of the bucket
cylinder 15 is controlled alone, the hydraulic fluid from the
second hydraulic pump 3 flows into the bucket control valve 16
through the parallel flow path 12a and the tandem flow path,
thereby reducing an excessive pressure loss occurring when the
hydraulic fluid from the second hydraulic pump 3 flows into the
bucket control valve 16 through only the parallel flow path
12a.
[0016] Meanwhile, in the case where two different attachments such
as the boom for performing a boom descending operation and the
bucket are driven simultaneously, the second center bypass path 12
is blocked by the control spool on a boom descending side and the
hydraulic fluid is supplied to the bucket cylinder 15 through only
the parallel flow path 12a. In this case, there occurs a problem in
that a sufficient flow path cannot be secured by a priority control
valve installed in the parallel flow path 12a, thereby inducing an
excessive pressure loss, and thus causing an energy loss.
[0017] In addition, a variable control valve as a throttle valve 24
(see FIG. 2) may be installed in the parallel flow path 12a, but
there is a limitation in securing the flow path using the throttle
device.
DETAILED DESCRIPTION OF THE INVENTION
Technical Problems
[0018] Accordingly, the present invention has been made to solve
the aforementioned problem occurring in the prior art, and it is an
object of the present invention to provide an attachment driving
control system for a construction machine, in which in the case
where two attachments having different operating pressures are
simultaneously driven as in a boom descending operation and a
bucket operation, a hydraulic fluid from the second hydraulic pump
is allowed to flow into the bucket control valve through a parallel
flow path and a tandem flow path, leading to a reduction in an
unnecessary pressure loss occurring in the control valve, thereby
reducing an energy loss and thus increasing an efficiency of a
hydraulic system.
Technical Solution
[0019] To accomplish the above object, there is provided an
attachment driving control system for a construction machine in
accordance with an embodiment of the present invention,
including:
[0020] an engine;
[0021] first and second variable displacement hydraulic pumps
connected to the engine and a pilot pump;
[0022] a swing control valve configured to control the drive of a
swing motor, an arm control valve configured to control the drive
of an arm cylinder, and a traveling control valve configured to
control the drive of a left traveling motor wherein the swing
control valve, the arm control valve, and the traveling control
valve are installed in a first center bypass path of the first
hydraulic pump so as to be connected to a parallel flow path,
respectively;
[0023] a boom control valve configured to control the drive of a
boom cylinder, a bucket control valve configured to control the
drive of a bucket cylinder, and a traveling control valve
configured to control the drive of a right traveling motor wherein
the boom control valve, the bucket control valve, and the traveling
control valve are installed in a second center bypass path of the
second hydraulic pump so as to be connected to a parallel flow
path, respectively;
[0024] pressure generation devices configured to output a control
signal corresponding to a manipulation amount;
[0025] a bleed flow path formed on a control spool on a boom
descending side of the boom control valve and configured to
maintain the second center bypass path in an opened state instead
of blocking the second center bypass path when the boom control
valve is shifted to descend the boom through the manipulation of
the pressure generation device; and
[0026] a center bypass shift valve installed on a lowermost
downstream side of the second center bypass path and configured to
be shifted by a control signal pressure for shifting the boom
control valve,
[0027] wherein a hydraulic fluid from the second hydraulic pump
flows into the boom control valve through the parallel flow path
and a tandem flow path connected to the second center bypass path
when a boom for performing a boom descending operation and an
attachment requiring an operating pressure relatively higher than
that of the boom are simultaneously driven.
[0028] In accordance with a preferred embodiment of the present
invention, the attachment is a bucket, and the control valve that
controls the attachment is the bucket control valve.
Advantageous Effect
[0029] The attachment driving control system for a construction
machine in accordance with an embodiment of the present invention
as constructed above has the following advantages.
[0030] In the case where two attachments having different operating
pressures are simultaneously driven as in a boom descending
operation and a bucket operation, a hydraulic fluid from the second
hydraulic pump is allowed to flow into the bucket control valve
through the parallel flow path and the tandem flow path (i.e., in
this case, a flow path can secured as much as a flow rate of the
hydraulic fluid passing through the tandem flow path), leading to a
reduction in a pressure loss occurring in the control valve,
thereby reducing an energy loss.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The above objects, other features and advantages of the
present invention will become more apparent by describing the
preferred embodiments thereof with reference to the accompanying
drawings, in which:
[0032] FIG. 1 is a hydraulic circuit diagram showing an attachment
driving control system for a construction machine in accordance
with the prior art;
[0033] FIG. 2 is an enlarged view showing of an main part of a
variable control valve applied to an attachment driving control
system for a construction machine in accordance with the prior
art;
[0034] FIG. 3 is a hydraulic circuit diagram showing a attachment
driving control system for a construction machine in accordance
with an embodiment of the present invention; and
[0035] FIG. 4 is an enlarged view showing of a main part of a
priority control valve applied to an attachment driving control
system for a construction machine in accordance with an embodiment
of the present invention.
[0036] *Explanation on Reference Numerals of Main Elements in the
Drawings*
[0037] 1: engine
[0038] 2: first hydraulic pump
[0039] 3: second hydraulic pump
[0040] 4: pilot pump
[0041] 5: first center bypass path
[0042] 6: swing motor
[0043] 7,9,11,14,16,18: control valve
[0044] 8: arm cylinder
[0045] 10,17: traveling motor
[0046] 13: boom cylinder
[0047] 15: bucket cylinder
[0048] 19,20: pressure generation device
[0049] 25: bleed flow path
[0050] 26: center bypass shift valve
PREFERRED EMBODIMENTS OF THE INVENTION
[0051] Now, preferred embodiments of the present invention will be
described in detail with reference to the accompanying drawings.
The matters defined in the description, such as the detailed
construction and elements, are nothing but specific details
provided to assist those of ordinary skill in the art in a
comprehensive understanding of the invention, and the present
invention is not limited to the embodiments disclosed
hereinafter.
[0052] An attachment driving control system for a construction
machine in accordance with an embodiment of the present invention
as shown in FIGS. 3 and 4 includes:
[0053] an engine 1;
[0054] first and second variable displacement hydraulic pumps
(hereinafter, referred to as "first and second hydraulic pumps") 2
and 3 that are connected to the engine 1 and a pilot pump 4;
[0055] a swing control valve 7 that controls the drive of a swing
motor 6, an arm control valve 9 that controls the drive of an arm
cylinder 8, and a traveling control valve 11 that controls the
drive of a left traveling motor 10 wherein the swing control valve,
the arm control valve, and the traveling control valve are
installed in a first center bypass path 5 of the first hydraulic
pump 2 so as to be connected to a parallel flow path 5a,
respectively;
[0056] a boom control valve 14a that controls the drive of a boom
cylinder 13, a bucket control valve 16 that controls the drive of a
bucket cylinder 15, and a traveling control valve 18 that controls
the drive of a right traveling motor 17 wherein the boom control
valve, the bucket control valve, and the traveling control valve
are installed in a second center bypass path 12 of the second
hydraulic pump 3 and 2 so as to be connected to a parallel flow
path 12a, respectively;
[0057] pressure generation devices 19 and 20 that outputs a control
signal corresponding to a manipulation amount;
[0058] a bleed flow path 25 that is formed on a control spool on a
boom descending side of the boom control valve 14a and maintains
the second center bypass path 12 in an opened state instead of
blocking the second center bypass path when the boom control valve
14a is shifted to descend the boom through the manipulation of the
pressure generation device 19; and a center bypass shift valve 26
that is installed on a lowermost downstream side of the second
center bypass path 12 and is shifted by a control signal pressure
for shifting the boom control valve 14a.
[0059] Thus, a hydraulic fluid from the second hydraulic pump 3
flows into the bucket control valve 16 through the parallel flow
path 12a and a tandem flow path connected to the second center
bypass path 12 when a boom for performing a boom descending
operation and an attachment (i.e., referring to a bucket) having an
operating pressure relatively higher than that of the boom are
simultaneously driven.
[0060] In this case, the configuration of the attachment driving
control system shown in FIG. 1 is the same as that of the
attachment driving control system shown in FIG. 1 except the bleed
flow path 25 that is formed on a control spool on a boom descending
side of the boom control valve 14a and maintains the second center
bypass path 12 in an opened state instead of blocking the second
center bypass path 12 when the boom control valve 14a is shifted to
descend the boom through the manipulation of the pressure
generation device 19, and the center bypass shift valve 26 that is
installed on the lowermost downstream side of the second center
bypass path 12 and is shifted by a control signal pressure for
shifting the boom control valve 14a. Thus, the detailed description
of the same configuration and operation thereof will be omitted to
avoid redundancy, and the same elements are denoted by the same
reference numerals.
[0061] Hereinafter, a use example of the attachment driving control
system for a construction machine in accordance with an embodiment
of the present invention will be described in detail with reference
to the accompanying drawings.
[0062] As shown in FIGS. 3 and 4, in the case where a boom
descending operation and a bucket operation are simultaneously
performed, the boom control valve 14a is shifted to the right on
the drawing sheet in response to a pilot signal pressure from the
pilot pump 4, which passes through the pressure generation device
19, by the manipulation of the pressure generation device 19. Thus,
a hydraulic fluid discharged from the second hydraulic pump 3 is
supplied to a small chamber of the boom cylinder 13 via a load
check valve 22 and the boom control valve 14a. At the same time, a
hydraulic fluid flowing out of a large chamber of the boom cylinder
13 returns to a hydraulic tank T via the boom control valve 14a and
a back pressure check valve 23. As a result, the boom cylinder 13
is driven in a retractable manner to cause the boom to descend.
[0063] In this case, the hydraulic fluid flowing out of the large
chamber of the boom cylinder 13 is partially regenerated to the
small chamber of the boom cylinder 13 through a regeneration line
formed on a control spool (i.e., referring to the boom control
valve 14a) on a boom descending side.
[0064] In the meantime, the hydraulic fluid discharged from the
second hydraulic pump 3 is supplied to an inlet side of the bucket
control valve 16 via the second center bypass path 12 and the bleed
flow path 25 formed on a control spool on a boom descending side of
the boom control valve 14a. Thus, the bleed flow path 25 is
connected to a spool path of the bucket control valve 16 via a load
check valve 27 of the bucket control valve 16. Meanwhile, a
hydraulic fluid passing through a priority control valve installed
on a parallel flow path 12a joins a hydraulic fluid passing through
the load check valve 27, and then flows into a spool of the bucket
control valve 16.
[0065] When the boom and the bucket having different operating
pressures are driven simultaneously, a hydraulic fluid from the
second hydraulic pump 3 flows into the spool of the bucket control
valve 16 through the parallel flow path 12a. At the same time, the
hydraulic fluid from the second hydraulic pump 3 also flows into
the spool of the spool of the bucket control valve 16 through the
second center bypass path 12. For this reason, a pressure loss is
reduced as much as a flow rate of a hydraulic fluid flowing into
the spool of bucket control valve 16 through the second center
bypass path 12. Likewise, the reduction in the pressure loss can
also be applied to the traveling control valve 18.
[0066] While the present invention has been described in connection
with the specific embodiments illustrated in the drawings, they are
merely illustrative, and the invention is not limited to these
embodiments. It is to be understood that various equivalent
modifications and variations of the embodiments can be made by a
person having an ordinary skill in the art without departing from
the spirit and scope of the present invention. Therefore, the true
technical scope of the present invention should not be defined by
the above-mentioned embodiments but should be defined by the
appended claims and equivalents thereof.
INDUSTRIAL APPLICABILITY
[0067] As described above, the attachment driving control system
for a construction machine in accordance with an embodiment of the
present invention is advantageous in that in the case where two
attachments having different operating pressures are simultaneously
driven as in a boom descending operation and a bucket operation, a
hydraulic fluid from the second hydraulic pump is allowed to flow
into the bucket control valve through the parallel flow path and
the tandem flow path, leading to a reduction in a pressure loss
occurring in the control valve, thereby increasing energy
efficiency of the hydraulic system.
* * * * *