U.S. patent application number 13/821452 was filed with the patent office on 2013-06-27 for flow rate control device for variable displacement type hydraulic pump for construction equipment.
This patent application is currently assigned to VOLVO CONSTRUCTION EQUIPMENT AB. The applicant listed for this patent is Hea-Gyoon Joung, Sang-Hee Lee, Hung-Ju Shin. Invention is credited to Hea-Gyoon Joung, Sang-Hee Lee, Hung-Ju Shin.
Application Number | 20130160439 13/821452 |
Document ID | / |
Family ID | 45810817 |
Filed Date | 2013-06-27 |
United States Patent
Application |
20130160439 |
Kind Code |
A1 |
Lee; Sang-Hee ; et
al. |
June 27, 2013 |
FLOW RATE CONTROL DEVICE FOR VARIABLE DISPLACEMENT TYPE HYDRAULIC
PUMP FOR CONSTRUCTION EQUIPMENT
Abstract
The present invention pertains to a hydraulic pressure control
device of a variable displacement type hydraulic pump for
construction equipment, wherein operable sections of operation
systems are formed in a wide manner while the hydraulic pump
discharges a relatively small flow rate compared with the operation
amount of the respective operation systems in the case of complex
operations, so as to improve the pressure loss and the fuel ratio
of the hydraulic pump. The device includes a flow rate controller,
which is preferably connected to an operation amount detecting
means and a swash plate control device, and receives operation
signals from the operation system of a control device that are
detected by the operation amount detecting means so as to control
the discharge flow rate of the hydraulic pump. In the case of the
complex operations, the flow rate controller pre-determines the
required flow rate of an actuator for the respective operation
systems via the operation signals of the operation systems and
subsequently operates the square root of the sum of the squares of
the respective required flow rates so as to determine the discharge
flow rate of the hydraulic pump, thereby controlling the swash
plate control device.
Inventors: |
Lee; Sang-Hee; (Changwon-si,
KR) ; Joung; Hea-Gyoon; (Busan, KR) ; Shin;
Hung-Ju; (Changwon-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lee; Sang-Hee
Joung; Hea-Gyoon
Shin; Hung-Ju |
Changwon-si
Busan
Changwon-si |
|
KR
KR
KR |
|
|
Assignee: |
VOLVO CONSTRUCTION EQUIPMENT
AB
Eskilstuna
SE
|
Family ID: |
45810817 |
Appl. No.: |
13/821452 |
Filed: |
September 9, 2010 |
PCT Filed: |
September 9, 2010 |
PCT NO: |
PCT/KR2010/005742 |
371 Date: |
March 7, 2013 |
Current U.S.
Class: |
60/384 |
Current CPC
Class: |
F15B 2211/6346 20130101;
F15B 2211/88 20130101; F15B 2211/20546 20130101; F15B 2211/255
20130101; E02F 9/2235 20130101; E02F 9/2282 20130101; E02F 9/2285
20130101; E02F 9/2296 20130101 |
Class at
Publication: |
60/384 |
International
Class: |
F04B 13/00 20060101
F04B013/00 |
Claims
1. A flow rate control apparatus of a variable displacement
hydraulic pump for a construction machine comprising: an engine; at
least one variable displacement hydraulic pump having a swash plate
control device for controlling an opening area thereof and
configured to be pumped by the engine to provide hydraulic
pressure; a plurality of actuators for work apparatuses including a
boom actuator or an arm actuator, a bucket actuator, and a swing
motor; a work apparatus control valve connected and installed
between the hydraulic pump and the actuators for work apparatuses,
and configured to control the hydraulic pressure discharged from
the hydraulic pump to perform a start, a stop, and a swing
operation of the actuators for the work apparatuses and the swing
motor during the spool shift; a manipulation amount detection means
configured to detect a manipulation amount of a manipulation device
to drive the actuators for work apparatuses; and a flow rate
controller connected to the manipulation amount detection means and
the swash plate control device, and configured to receive a work
apparatus manipulation signal of the manipulation device, which is
detected by the manipulation amount detection means and to control
a discharge flow rate of the hydraulic pump, wherein the flow rate
controller pre-determines the required flow rates of the respective
actuators for work apparatuses through the work apparatus
manipulation signal during a combined operation, and then controls
the swash plate control device by calculating the square root of
the sum of squares of the respective required flow rates to
determine the discharge flow rate of the hydraulic pump.
2. The flow rate control apparatus of a variable displacement
hydraulic pump according to claim 1, wherein the manipulation
amount detection means is constructed as a pilot pressure detection
sensor.
3. The flow rate control apparatus of a variable displacement
hydraulic pump according to claim 1, wherein the swash plate
control device is constructed as an electro proportional pressure
reducing valve.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a flow rate control
apparatus of a variable displacement hydraulic pump for a
construction machine including an excavator. More particularly, the
present invention relates to an improved flow rate control
apparatus of a variable displacement hydraulic pump for a
construction machine, in which an opening area of a hydraulic pump
is controlled to be large by a controller that pre-determines a
flow rate required by a plurality of actuators during a combined
operation of work apparatuses for a construction machine so that a
pressure loss of the hydraulic pump can be reduced and fuel
efficiency can be improved, and in which during a combined
operation, a hydraulic pump discharges a relatively small amount of
hydraulic fluid in comparison to a manipulation amount of
respective work apparatuses to make wide a manipulation period
range of a manipulation device.
BACKGROUND OF THE INVENTION
[0002] A construction machine including an excavator or a hydraulic
shovel is provided with a hydraulic circuit configured so that a
work apparatus including a boom, an arm, a bucket and a swing motor
is driven by the pressure of a hydraulic fluid discharged from a
hydraulic pump.
[0003] Referring to FIG. 1, a hydraulic excavator 1 includes a
crawler-type lower traveling structure 2, an upper swing structure
3 swingably supported on the lower traveling structure 2, and a
work apparatus mounted on the upper swing structure 3. The work
apparatus generally includes a boom 5 configured so that its base
is ascendably and descendably supported on the upper swing
structure 3, an arm 6 provided at an end of the boom 5, a bucket 7
mounted at a front end of the boom 5, and a swing motor (not shown)
configured to provide power during the swing operation of the upper
swing structure 3.
[0004] Depending on a specification of the equipment, one variable
displacement hydraulic pump is frequently used to supply a
hydraulic pressure to the work apparatus, and the sum of the
required flow rates spent by the actuators for work apparatuses
during a combined operation in which a plurality of actuators 14 is
controlled by a manipulation device including a manipulation lever
or a joystick is controlled to be a discharge flow rate of the
hydraulic pump.
[0005] That is, during the combined operation, the discharge flow
rate of the variable displacement hydraulic pump is determined by
the flow rate required by the respective actuators for work
apparatuses, which is controlled by the following equation:
"Hydraulic Pump Discharge Flow Rate=Required flow rate of first
actuator+Required flow rate of second actuator+Required flow rate
of third actuator".
[0006] In the above equation, it can be understood that the first
actuator is a boom actuator 14a, the second actuator is a bucket
actuator 14c, and the third actuator is swing motor (not shown). It
is of course to be noted that a work apparatus can be additionally
provided to the hydraulic construction machine.
[0007] The control method of the discharge flow rate of the
conventional hydraulic pump using the above-mentioned equation
entails a problem in that a relatively large amount of hydraulic
fluid is discharged from an opening area of a pump flow path,
leading to a great increase in a pressure loss, which influences
the fuel efficiency and thus increases fuel consumption.
[0008] In addition, during the combined operation, the maximum
discharge flow rate of the hydraulic pump is reached rapidly and
thus the control range of the discharge flow rate of the hydraulic
pump according to a pilot pressure of the manipulation device is
narrowed, resulting in a deterioration of manipulability.
[0009] Meanwhile, Korean Patent Laid-Open Publication No.
2001-0033699 discloses a flow rate control apparatus for allowing
an output flow rate of the hydraulic pump to be controlled to be a
distributed flow rate that is preset in each hydraulic actuator in
view of a problem involved in a flow rate control apparatus for a
hydraulic shovel in that manipulability is deteriorated during a
combined operation.
[0010] During the combined operation, the flow rate control
apparatus calculates the sum of the absolute values of the required
flow rates of the hydraulic actuators to obtain the required flow
rates of the hydraulic actuators, and uses the calculated sum of
the absolute values in a control method of the pump required flow
rate. Thus, it is possible to prevent the sum of the required flow
rates of the hydraulic actuators from exceeding the maximum
discharge flow rate of the hydraulic pump and control the sum of
the required flow rates of the hydraulic actuators to be a
distributed flow rate according to actuators for work apparatuses
during the combined operation.
[0011] Such a flow rate control method using the sum of the
absolute values of the required flow rates of the hydraulic
actuators can also avoid a shortcoming in that the distributed flow
rate is larger than the required flow rate needed by the
manipulation of a manipulation device such as a manipulation lever
or a joystick. However, this flow rate control method still does
not suggest a solution to problems in that a pressure loss occurs
during the combined operation and in that during the combined
operation, the maximum discharge flow rate of the hydraulic pump is
reached rapidly and thus the control range of the discharge flow
rate of the hydraulic pump by the manipulation device is narrowed,
resulting in a deterioration of manipulability.
DETAILED DESCRIPTION OF THE INVENTION
Technical Problems
[0012] Accordingly, the present invention was made to solve the
aforementioned problem occurring in the prior art, and it is an
object of the present invention to provide a flow rate control
apparatus of a variable displacement hydraulic pump for a
construction machine, in which the discharge flow rate of a
hydraulic pump is controlled to show an effect of making wide an
opening area of the hydraulic pump according to the matching
condition of the actuators for work apparatuses, thereby reducing a
pressure loss and improving fuel efficiency.
Technical Solution
[0013] To accomplish the above object, in accordance with the
present invention, there is provided a flow rate control apparatus
of a variable displacement hydraulic pump for a construction
machine including: an engine; at least one variable displacement
hydraulic pump having a swash plate control device for controlling
an opening area thereof and configured to be pumped by the engine
to provide hydraulic pressure; a plurality of actuators for work
apparatuses including a boom actuator or an arm actuator, a bucket
actuator, and a swing motor; a work apparatus control valve
connected and installed between the hydraulic pump and the
actuators for work apparatuses, and configured to control the
hydraulic pressure discharged from the hydraulic pump to perform a
start, a stop, and a swing operation of the actuators for the work
apparatuses and the swing motor during the spool shift; a
manipulation amount detection means configured to detect a
manipulation amount of a manipulation device to drive the actuators
for work apparatuses; and a flow rate controller connected to the
manipulation amount detection means and the swash plate control
device, and configured to receive a work apparatus manipulation
signal of the manipulation device, which is detected by the
manipulation amount detection means and to control a discharge flow
rate of the hydraulic pump, wherein the flow rate controller
pre-determines the required flow rates of the respective actuators
for work apparatuses through the work apparatus manipulation signal
during a combined operation, and then controls the swash plate
control device by calculating the square root of the sum of squares
of the respective required flow rates to determine the discharge
flow rate of the hydraulic pump.
Advantageous Effect
[0014] The flow rate control apparatus of a variable displacement
hydraulic pump for a construction machine according to the present
invention has an advantage in that it controls an opening area of
the hydraulic pump based on the calculated the square root of the
sum of squares of the required flow rates to drive the respective
actuators for work apparatuses, so that the plurality of actuators
for work apparatuses can be simultaneously manipulated or the
opening area of the hydraulic pump, which is relatively large as
compared to the prior art, can be secured during a combined
operation (this means that the discharge flow rate of hydraulic
pump is relatively small), thereby reducing a pressure loss of the
hydraulic pump and improving the operation efficiency and fuel
efficiency.
[0015] In addition, the flow rate control apparatus of a variable
displacement hydraulic pump for a construction machine according to
the present invention has another advantage in that the hydraulic
pump discharges a relatively small amount of hydraulic fluid in the
same period range in comparison with the prior art in the
manipulation of the manipulation device and the control of the
discharge flow rate of the hydraulic pump according to the
manipulation of the manipulation device to perform a combined
operation, and the manipulation period range of the manipulation
device is made relatively wide so that manipulability of the
equipment can be improved.
BRIEF DESCRIPTION OF THE INVENTION
[0016] 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:
[0017] FIG. 1 is a schematic perspective view showing an excavator
for a construction machine according to the prior art;
[0018] FIG. 2 is a flow chart for controlling the discharge flow
rate of a hydraulic pump according to the prior art;
[0019] FIG. 3 is a block diagram schematically showing the
construction of a flow rate control apparatus according to an
embodiment of the present invention;
[0020] FIG. 4 is a flow chart for controlling the discharge flow
rate of a hydraulic pump according to the present invention;
[0021] FIG. 5 is a graph showing the flow rate characteristics of
the hydraulic pump according to the present invention.
PREFERRED EMBODIMENTS OF THE INVENTION
[0022] 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.
[0023] Here, the terminology or words used in the specification and
the claims of the present invention should not be interpreted as
typical meanings or lexical meanings, and they should be
interpreted as the meaning and concept conforming to the
technological idea of the present invention on the basis of the
idea that the inventor can define the concept of the words
appropriately in order to illustrate his invention in the best
manner.
[0024] Hereinafter, a preferred embodiment of the present invention
will be described in more detail with reference to the accompanying
drawings.
[0025] Referring to FIGS. 3 and 4, the flow rate control apparatus
of a variable displacement hydraulic pump for a construction
machine according to the present invention includes:
[0026] an engine 10;
[0027] at least one variable displacement hydraulic pump 12 having
a swash plate control device 11 for controlling an opening area
thereof and configured to be pumped by the engine 10 to provide
hydraulic pressure;
[0028] a plurality of actuators 14 for work apparatuses including a
boom actuator or an arm actuator, a bucket actuator, and a swing
motor;
[0029] a work apparatus control valve 15 connected and installed
between the hydraulic pump 12 and the actuators 14 for work
apparatuses, and configured to control the hydraulic pressure
discharged from the hydraulic pump to perform a start, a stop, and
a swing operation of the actuators for the work apparatuses and the
swing motor during the spool shift;
[0030] a manipulation amount detection means 17 configured to
detect a manipulation amount of a manipulation device 16 to drive
the actuators 14 for work apparatuses; and
[0031] a flow rate controller 18 connected to the manipulation
amount detection means 17 and the swash plate control device 11,
and configured to receive a work apparatus manipulation signal of
the manipulation device 16, which is detected by the manipulation
amount detection means 17 and to control a discharge flow rate of
the hydraulic pump 12.
[0032] The flow rate controller 18 pre-determines the required flow
rates of the respective actuators 15 for work apparatuses through
the work apparatus manipulation signal during a combined operation,
and then controls the swash plate control device 11 by calculating
the square root of the sum of squares of the respective required
flow rates to determine the discharge flow rate of the hydraulic
pump 12.
[0033] In addition, the manipulation amount detection means 17 is
constructed as a pilot pressure detection sensor, and the swash
plate control device 11 is constructed as an electro proportional
pressure reducing valve.
[0034] The operation principle of the flow rate control apparatus
of a variable displacement hydraulic pump for a construction
machine according to an embodiment of the present invention will be
described in further detail with reference to FIGS. 3 to 5.
[0035] In an embodiment of the present invention, the hydraulic
excavator 1 includes a crawler-type lower traveling structure 2, an
upper swing structure 3 swingably supported on the lower traveling
structure 2, and a work apparatus mounted on the upper swing
structure 3. The work apparatus generally includes a boom 5
configured so that its base is ascendably and descendably supported
on the upper swing structure 3, an arm 6 provided at an end of the
boom 5, a bucket 7 mounted at a front end of the boom 5, and a
swing motor (not shown) configured to provide power during the
swing operation of the upper swing structure 3 as in the prior
art.
[0036] In addition, the boom 5, the arm 6 and the bucket 7 are
operated by respective actuators 14 that are expanded and contacted
by hydraulic pressure.
[0037] Particularly, in the flow rate control apparatus of a
variable displacement hydraulic pump for a construction machine
according to an embodiment of the present invention, when an
operator manipulates a manipulation device 16, for example, a
manipulation lever or a joystick to drive the actuators 14 for work
apparatuses, the manipulation amount of a work apparatus
manipulation signal including a pilot pressure or an electric
signal is detected by the manipulation amount detection means
17.
[0038] The flow rate controller 18 is connected to the manipulation
amount detection means 17 and the swash plate control device 11,
and receives a work apparatus manipulation signal of the
manipulation device 16, which is detected by the manipulation
amount detection means 17 and controls a discharge flow rate of the
hydraulic pump 12.
[0039] Preferably, the flow rate controller 18 pre-determines the
required flow rates of the respective actuators 15 for work
apparatuses through the work apparatus manipulation signal during a
combined operation, and then controls the swash plate control
device 11 by calculating the square root of the sum of squares of
the respective required flow rates to determine the discharge flow
rate of the hydraulic pump 12.
[0040] The manipulation device 16 is installed at a pilot pump 13,
and the manipulation amount of the manipulation device 16 is
detected by a pilot pressure detection sensor of the manipulation
amount detection means 17.
[0041] According to an embodiment of the present invention, the
discharge flow rate of the hydraulic pump 12 is determined by
performing a step S100 of detecting the manipulation amount of the
manipulation device 16 to calculate the required flow rates of the
respective actuators 14, a step S200 of calculating the square root
of the sum of squares of the required flow rates of the respective
actuators 14 calculated in the step S100, and a step S300 of
outputting a control signal corresponding to a result determined at
the step S200 to control the swash plate control device 11.
[0042] More specifically, the flow rate controller 18 according to
the present invention merely does not calculate the sum of the
required flow rates of the respective actuators 14 for work
apparatuses when a hydraulic pump discharge flow rate is set unlike
the conventional flow rate control method. Instead, the flow rate
controller 18 calculates the square root of the sum of squares of
the respective required flow rates of the actuators 14 for work
apparatuses according to a work apparatus manipulation signal of
the manipulation device 16 detected by the manipulation amount
detection means 17 and determines the calculated square root value
to be the discharge flow rate of the hydraulic pump 12.
[0043] In other words, the discharge flow rate of the hydraulic
pump determined by the flow rate controller 18 can be defined by
the following equation:
The sum of squares of the required flow rates of the actuators for
work apparatuses=(required flow rate of first
actuator).sup.2+(required flow rate of second
actuator).sup.2+(required flow rate of third actuator).sup.2 . . .
.
[0044] Here, the flow rate controller 18 controls the discharge
flow rate of the hydraulic pump by calculating the square root of
the sum of squares of the required flow rates of the actuators for
work apparatuses as defined above and using an output signal of the
swash plate control device 11 corresponding to a result of the
calculation. The discharge flow rate of the hydraulic pump can be
defined by the following equation:
Hydraulic Pump Discharge Flow Rate=((Required flow rate of first
actuator).sup.2+(Required flow rate of second
actuator).sup.2+(Required flow rate of third actuator).sup.2 . . .
. )
[0045] In order to compare the characteristics of the discharge
flow rate of the hydraulic pump controlled by the flow rate
controller 18 according to the present invention, during the
combined operation of two actuators for work apparatuses, for
example, the boom actuator and the bucket actuator, a comparison of
the flow rate characteristics is made between the conventional flow
rate control method of simply adding the required flow rates of the
actuators and the inventive flow rate control method. A result of
the comparison shows that the inventive flow rate control method
controls the maximum flow rate of the hydraulic pump in a
relatively delayed period in comparison with the conventional flow
rate control method.
[0046] That is, as shown in FIG. 5, when the maximum discharge flow
rate performance of the hydraulic pump 12 is set to be constant,
the discharge flow rate control characteristic line B of the
hydraulic pump 12 according to the present invention has a
relatively small gradient and shows a relatively long delay period
to reach the maximum flow rate in comparison with the discharge
flow rate control characteristic line A of the hydraulic pump 12
according to the prior art.
[0047] This means that when one actuator 14 is manipulated alone,
there is no difference in control characteristics between the
inventive flow rate control method and the conventional flow rate
control method. In addition, the flow rate control apparatus of a
variable displacement hydraulic pump for a construction machine
according to the present invention has the characteristics that
when two or more actuators 14 are manipulated simultaneously or a
combined operation is performed, the opening area of the hydraulic
pump is controlled such that the hydraulic pump discharges a
relatively small amount of hydraulic fluid in comparison to the
prior art.
[0048] Additionally, a relatively large opening area can be secured
with respect to the same discharge flow rate of the hydraulic pump
12, and thus a pressure loss can be greatly reduced as well as the
operation efficiency of the hydraulic pump 12 and the fuel
efficiency can be improved.
[0049] In the meantime, the flow rate control apparatus of a
variable displacement hydraulic pump for a construction machine
according to the present invention has the characteristics that
when the manipulation amount of the manipulation device 16 is
maintained constantly during a combined operation, the hydraulic
pump 12 discharges a relatively small amount of hydraulic fluid in
comparison to the prior art and a relatively large manipulation
amount as compared to the prior art is required to discharge the
same amount of hydraulic fluid as that in the prior art in terms of
the control of the manipulation device 16.
[0050] By virtue of such characteristics, the flow rate control
apparatus of a variable displacement hydraulic pump for a
construction machine according to the present invention provides an
operator with a relatively wide manipulation period range as
compared to the prior art in the manipulation of the manipulation
device 16 including a manipulation lever or a joystick so that
manipulability can be maintained smoothly and stably.
INDUSTRIAL APPLICABILITY
[0051] As described above, the present invention is very useful in
a the flow rate control apparatus of a variable displacement
hydraulic pump for a construction machine, in which the hydraulic
pump discharges a relatively small amount of hydraulic fluid in the
same period range in comparison with the prior art in the
manipulation of the manipulation device and the control of the
discharge flow rate of the hydraulic pump according to the
manipulation of the manipulation device to perform a combined
operation, and the manipulation period range of the manipulation
device is made relatively wide so that manipulability can be
improved and a pressure loss of the hydraulic pump can be
reduced.
* * * * *