Patent Application
20130269332
The present invention relates to an energy regeneration system for a construction machine, which enables energy to be regenerated when the construction machine performs a combined operation of boom down and arm out. More particularly, the present invention relates to an energy regeneration system for a construction machine, which enables hydraulic energy returned by the boom down operation to be regenerated during the arm out operation.
A hydraulic system in which a boom cylinder and an arm cylinder are joined to each other in accordance with the prior art as shown in
first and second variable displacement hydraulic pumps (hereinafter, referred to as “first and second hydraulic pumps”) 1 and 2 that are connected to an engine (not shown);
an arm cylinder 3 that is connected to the first hydraulic pump 1;
a control valve 4 that is mounted in a discharge flow path of the first hydraulic pump 1 and controls the arm in and out operation of the arm cylinder 3;
a boom cylinder 5 that is connected to the second hydraulic pump 2;
a control valve 6 that is mounted in a discharge flow path of the second hydraulic pump 2 and controls the boom up and down operation of the boom cylinder 5; and
a confluence flow path 7 that connects the discharge flow path of the first hydraulic pump 1 and the discharge flow path of the second hydraulic pump 2 to each other in parallel, and allows the hydraulic fluids discharged from the first and second hydraulic pumps 1 and 2 to join each other therein depending on the work condition to secure the drive speed of a corresponding actuator.
In the hydraulic system as constructed above, when the boom down operation is performed by shifting a spool in a left direction on the drawing in response to a pilot signal pressure supplied to the control valve 6, the hydraulic fluid discharged from the second hydraulic pump 2 is supplied to a small chamber of the boom cylinder 5 via the control valve 6. In this case, some of the hydraulic fluid returned from a large chamber of the boom cylinder 5 is supplied to the small chamber of the boom cylinder 5.
As such, during the boom down operation, some of the hydraulic fluid in a high pressure state, which is returned to a second hydraulic tank T from the large chamber of the boom cylinder 5, is supplied to the small chamber in a low pressure state of the boom cylinder 5 and is regenerated in the small chamber, so that the efficiency of the hydraulic energy discharged from the second hydraulic pump 2. In this case, the hydraulic fluid is supplied to the small chamber by a difference in the cross-sectional area of the boom cylinder 5, and the remaining hydraulic fluid is returned to the second hydraulic tank T.
In addition, during the arm out operation alone, a discharge flow rate in which the flow rates of the hydraulic fluids from the first hydraulic pump 1 and the second hydraulic pump 2 join each other is required so that the construction machine can be driven under the condition of a high-load generated from the arm cylinder 3.
Meanwhile, an excavation work is generally performed through a combined operation of boom down and arm out in order to increase the work efficiency in terms of the properties of an excavator or the like. In this case, the hydraulic fluid supplied to the boom cylinder 5 from the second hydraulic pump 2 cannot be supplied to the arm cylinder 3 during the arm out operation due to a low pressure of a supply-side hydraulic fluid during the boom down operation.
Thus, the conventional hydraulic system entails a problem in that the workability of the arm out operation during the combined operation of boom down and arm out is relatively remarkably deteriorated as compared to that of the arm out operation alone.
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 an energy regeneration system for a construction machine, in which when the construction machine performs a combined_operation of boom down and arm out, hydraulic energy returned by the boom down operation can be supplied to the arm cylinder, thereby improving the workability of the arm out operation.
Another object of the present invention to provide an energy regeneration system for a construction machine, in which a supply flow path (meter-in) and a return flow path (meter-out) with respect to a hydraulic actuator are controlled independently, and the pressure of the hydraulic actuator is detected in real-time, so that the hydraulic fluid can be supplied to an arm cylinder at the time of performing the combined operation.
Technical Solution To accomplish the above object, in accordance with an embodiment of the present invention, there is provided an energy regeneration system for a construction machine, which includes:
According to a more preferable embodiment, the energy regeneration system for a construction machine further includes: a first variable flow rate control valve mounted in the boom down supply flow path and configured to control the hydraulic fluid supplied to the low-pressure chamber of the boom cylinder from the second hydraulic pump; and a second variable flow rate control valve mounted in the boom down return flow path and configured to control the hydraulic fluid returned to the second hydraulic tank from the high-pressure chamber of the boom cylinder.
In accordance with an embodiment of the present invention, the energy regeneration system for a construction machine further includes: a third variable flow rate control valve mounted in the arm out supply flow path and configured to control the hydraulic fluid supplied to the low-pressure chamber of the arm cylinder from the first hydraulic pump; and a fourth variable flow rate control valve mounted in the arm out return flow path and configured to control the hydraulic fluid returned to the first hydraulic tank T from the high-pressure chamber of the arm cylinder.
In accordance with an embodiment of the present invention, the energy regeneration system for a construction machine further includes: a fifth variable flow rate control valve mounted in the confluence and regeneration flow path and configured to control the hydraulic fluid supplied to the low-pressure chamber of the arm cylinder from the high-pressure chamber of the boom cylinder.
The detection means includes a first pressure sensor configured to detect the pressure generated from the high-pressure chamber of the boom cylinder, and a second pressure sensor configured to detect a discharge pressure supplied to the low-pressure chamber of the arm cylinder from the first hydraulic pump.
The energy regeneration system for a construction machine in accordance with an embodiment of the present invention as constructed above has the following advantages.
When an excavator performs a combined operation of boom down and arm out, hydraulic energy returned by the boom down operation can be supplied to the arm cylinder, thereby improving the workability of the arm out operation.
In addition, the supply flow path (meter-in) and the return flow path (meter-out) with respect to the hydraulic actuator are controlled independently, and the pressure of the hydraulic actuator (i.e., boom cylinder or the like) is detected in real-time, thereby reducing the manufacturing cost owing to compactness of the hydraulic system.
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:
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.
An energy regeneration system for a construction machine in accordance with an embodiment of the present invention as shown in
In accordance with an embodiment of the present invention, the energy regeneration system for a construction machine further includes: a first variable flow rate control valve 21 mounted in the boom down supply flow path 16 and configured to have an open area that can be changed in response to a control signal to control the flow rate or the pressure of the hydraulic fluid supplied to the low-pressure chamber of the boom cylinder 17 from the second hydraulic pump 12; and a second variable flow rate control valve 22 mounted in the boom down return flow path 18 and configured to have an open area that can be changed in response to a control signal to control the flow rate or the pressure of the hydraulic fluid returned to the second hydraulic tank T from the high-pressure chamber of the boom cylinder 17.
In accordance with an embodiment of the present invention, the energy regeneration system for a construction machine further includes: a third variable flow rate control valve 23 mounted in the arm out supply flow path 13 and configured to have an open area that can be changed in response to a control signal to control the flow rate or the pressure of the hydraulic fluid supplied to the low-pressure chamber of the arm cylinder 14 from the first hydraulic pump 11; and a fourth variable flow rate control valve 24 mounted in the arm out return flow path 15 and configured to have an open area that can be changed in response to a control signal to control the flow rate or the pressure of the hydraulic fluid returned to the first hydraulic tank T from the high-pressure chamber of the arm cylinder 14.
In accordance with an embodiment of the present invention, the energy regeneration system for a construction machine further includes: a fifth variable flow rate control valve 25 mounted in the confluence and regeneration flow path 19 and configured to have an open area that can be changed in response to a control signal to control the flow rate or the pressure of the hydraulic fluid supplied to the low-pressure chamber of the arm cylinder 14 from the high-pressure chamber of the boom cylinder 17.
The detection means includes a first pressure sensor 26 configured to detect the pressure generated from the high-pressure chamber of the boom cylinder 17, and a second pressure sensor 27 configured to detect a discharge pressure supplied to the low-pressure chamber of the arm cylinder 14 from the first hydraulic pump 11.
In
Hereinafter, a use example of the energy regeneration system for a construction machine in accordance with the present invention will be described in detail with reference to the companying drawings.
Referring to
In the meantime, the cross-sectional areas of the openings of the third variable flow rate control valve 23 mounted in the arm out supply flow path 13 and the fourth variable flow rate control valve 24 mounted in the arm out return flow path 15 are controlled, respectively, so as to control the flow rate of the hydraulic fluid passing through the openings of the third and fourth variable flow rate control valves so that the drive of the arm cylinder 14 can be controlled.
Referring to
First, some of the hydraulic fluid discharged from the boom cylinder 17 for the purpose of being returned to the second hydraulic tank T is supplied to and regenerated in the small chamber of the arm cylinder 14 along the arm out supply flow path 13 via the fifth variable flow rate control valve 25 mounted in the confluence and regeneration flow path 19.
Second, some of the hydraulic fluid discharged from the boom cylinder 17 for the purpose of being returned to the second hydraulic tank T is re-supplied to and regenerated in the small chamber of the boom cylinder 17 along the boom down supply flow path 16 via the second variable flow rate control valve 22 mounted in the boom down return flow path 18.
Third, some of the hydraulic fluid discharged from the boom cylinder 17 for the purpose of being returned to the second hydraulic tank T is returned to the second hydraulic tank T along the boom down return flow path 18. That is, during the boom down operation, some of the hydraulic fluid discharged from the boom cylinder 17 for the purpose of being returned to the second hydraulic tank T is re-supplied to the small chamber of the boom cylinder 17 or is supplied to and regenerated in the small chamber of the arm cylinder 14 by a difference in the cross-sectional area of the boom cylinder 17.
In the meantime, the cross-sectional areas of the openings of the first variable flow rate control valve 21 mounted in the boom down supply flow path 16 and the second variable flow rate control valve 22 mounted in the boom down return flow path 18 are controlled, respectively, so as to control the flow rate of the hydraulic fluid passing through the openings of the first and second variable flow rate control valves so that the drive of the boom cylinder 17 can be controlled.
Hereinafter, the flow rate of the hydraulic fluid supplied to the arm cylinder 14 and the boom cylinder 17 from the first hydraulic pump 11 and the second hydraulic pump 12 will be described.
As shown in
By virtue of this configuration, the arm cylinder 14 simultaneously receives the flow rate Qa of the hydraulic fluid regeneratingly supplied thereto from the boom cylinder 17 and the flow rate Q1 of the hydraulic fluid supplied thereto from the first hydraulic pump 11 so that the flow rate of the hydraulic fluid supplied to the arm cylinder 14 can be secured, thereby improving the workability of the arm out operation. In the meantime, the hydraulic fluid can be returned to the first hydraulic tank T from the large chamber of the arm cylinder 14 by a flow rate Q3 (=Q1+Qa).
As described above, the supply flow paths (meter-in) and the return flow paths (meter-out) of the boom cylinder 17 and the arm cylinder 14 are independently controlled by the first variable flow rate control valve 21 mounted in the boom down supply flow path 16 and the third variable flow rate control valve 23 mounted in the arm out supply flow path 13, and the second variable flow rate control valve 22 mounted in the boom down return flow path 18 and the fourth variable flow rate control valve 24 mounted in the arm out return flow path 15, respectively.
In the meantime, the pressures of the boom cylinder 17 and the arm cylinder 14 can be detected in real-time by the first pressure sensor 26 mounted in the boom down return flow path 18, and the third pressure sensor 28 mounted in the arm out supply flow path 13.
As shown in
At step S200, a pressure value Pa of the large chamber of the boom cylinder 17 detected by the first pressure sensor 26 is compared with a discharge pressure value P1 of the first hydraulic pump 11 detected by the second pressure sensor 27. If it is determined at step S200 that the pressure value Pa of the large chamber of the boom cylinder 17 is greater than the discharge pressure value P1 of the first hydraulic pump 11 (i.e., Pa>P1), then the program proceeds to step S300. On the contrary, if it is determined at step S200 that the pressure value Pa of the large chamber of the boom cylinder 17 is smaller than the discharge pressure value P1 of the first hydraulic pump 11 (i.e., Pa<P1), then the program proceeds to step 4300.
As can be seen at step S300, if the pressure value Pa of the large chamber of the boom cylinder 17 is greater than the discharge pressure value P1 of the first hydraulic pump 11 (i.e., Pa>P1), then the hydraulic fluid discharged from the large chamber of the boom cylinder 17 for the purpose of being returned to the second hydraulic tank T can be supplied to and regenerated in the small chamber of the arm cylinder 14. In other words, the hydraulic fluid discharged from the large chamber of the boom cylinder 17 for the purpose of being returned to the second hydraulic tank T can be supplied to and regenerated in the small chamber of the arm cylinder 14 by controlling the cross-sectional areas of the openings of the fifth variable flow rate control valve 25 mounted in the confluence and regeneration flow path 19 and the second variable flow rate control valve 22 mounted in the boom down return flow path 18, respectively.
In this case, the cross-sectional areas (i.e., A area, B area, C area, and D area) of the openings of the first, second, third, and fifth variable flow rate control valves 21, 22, 23 and 25 are controlled to be respective different values in response to a control signal applied from the outside.
Thus, during the boom down operation, the discharge pressure value of the first hydraulic pump 11 is detected through the flow rate of the hydraulic fluid returned and regeneratingly supplied to the arm cylinder 11 to control the drive of the first hydraulic pump 11, so that a power for driving the first hydraulic pump 11 driven to supply the hydraulic fluid to the arm cylinder 14 can be reduced.
As can be seen at step S400, if the pressure value Pa of the large chamber of the boom cylinder 17 is smaller than the discharge pressure value P1 of the first hydraulic pump 11 (i.e., Pa<P1), then the hydraulic fluid discharged from the large chamber of the boom cylinder 17 for the purpose of being returned to the second hydraulic tank T cannot be supplied to and regenerated in the small chamber of the arm cylinder 14. In this case, the cross-sectional areas (i.e., A′ area, B′ area, C′ area, and 0 (close)) of the openings of the first, second, third, and fifth variable flow rate control valves 21, 22, 23 and 25 are controlled to be respective different values in response to a control signal applied from the outside.
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.
As described above, in the energy regeneration system for a construction machine in accordance with an embodiment of the present invention, when an excavator performs a combined operation of boom down and arm out, hydraulic energy returned by the boom down operation can be supplied to the arm cylinder, thereby improving the workability of the arm out operation.
In addition, the supply flow path (meter-in) and the return flow path (meter-out) with respect to the hydraulic actuator are controlled independently, and the pressure of the hydraulic actuator is detected in real-time, thereby implementing compactness of the hydraulic system.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/KR10/09354 | 12/27/2010 | WO | 00 | 6/21/2013 |
