KR20180058317A - Hydraulic energy recovery system for construction-machinery - Google Patents

Abstract

Disclosed is a hydraulic energy recovery system for construction machinery, capable of saving energy thereof. According to the present invention, the hydraulic energy recovery system for construction machinery comprises: high and low load side supply lines (4, 5) branched from a main hydraulic line (3) of a hydraulic pump (2) in parallel to be connected to high and low load actuators (100, 200); high and low load side control valves (10, 20) to control the high and low load actuators (100, 200); a compressing hydraulic line (300) and a compressor (310) branched from any one of the first and second hydraulic lines (201, 202) of the low load actuator (200); and a hydraulic extraction line (400) branched from the compressing hydraulic line (300) to extract the pressure energy stored in the compressor (310) and supply the energy to a third operation unit (500).

Description

Technical Field [0001] The present invention relates to a hydraulic energy recovery system for construction equipment,

The present invention relates to a hydraulic energy recovery system for a construction machine that can save energy by recovering and storing pressure loss energy of a hydraulic actuator in a construction machine and making it available for an operation terminal.

In a construction machine such as an excavator, a wheel loader, and a forklift, work is performed by moving a plurality of hydraulic actuators using pressure oil discharged from a hydraulic pump.

In the hydraulic energy recovery system of such a construction machine, one or a plurality of hydraulic pumps are provided, and a plurality of hydraulic actuators are connected in parallel to each hydraulic pump so that the hydraulic actuator can be operated solely by pressure oil discharged from one hydraulic pump Or a plurality of operations are carried out simultaneously.

For example, in a so-called "cargo operation" where excavators dig deeper into trucks, excavators dig deeper into buckets, load them on trucks with simultaneous revolving movements while lifting the bucket with the soil up.

For this combined movement, the excavator has a boom connected to the vehicle body, an arm connected to the boom, and a bucket connected to the arm, and as a hydraulic actuator for moving the boom cylinder, A female cylinder, and a bucket cylinder, together with a hydraulic motor for driving for driving the lower running body and a hydraulic motor for turning for driving the upper turning body.

Hydraulic actuators including a boom cylinder, an arm cylinder, a bucket cylinder, a hydraulic motor for driving, and a hydraulic motor for swiveling are connected to one or a plurality of hydraulic pumps driven by a power source (engine or electric motor) equipped in the excavator , And hydraulic oil discharged from each hydraulic pump.

In addition, each hydraulic actuator is provided with a control valve, and the control valve is switched (blocked and switched) and the opening degree is controlled in accordance with the operation direction and the manipulated variable of the operating lever by the driver and the direction of the pressure oil supplied to each of the hydraulic actuators Thereby controlling the flow rate (see Patent Documents 1 to 4).

1 is a view showing a hydraulic control system in which a plurality of actuators in a general construction machine have a high-load actuator and a low-load actuator, and a plurality of actuators are connected to a single hydraulic pump. Two or more hydraulic pumps may be connected to one hydraulic pump, and a plurality of such hydraulic pumps and actuator groups may be provided. E.g. In Patent Document 2 (Korean Patent Laid-Open Publication No. 10-2015-0033928), four actuators are connected to two hydraulic pumps, respectively.

1, this type of hydraulic control system includes a hydraulic pump 2 driven by a power source 1 such as an engine or an electric motor of a construction machine, a main hydraulic line 3 of the hydraulic pump 2, And a high load side control valve (not shown) for controlling the operation of the high load actuator 100 and the low load actuator 200 respectively connected to the high load side supply line 4 and the low load side supply line 5, 10 and a low-load-side control valve 20.

The high load side control valve 10 and the low load side control valve 20 each have a spool therein and are provided with a spool for the high load side control valve 10 and the low load side control valve 20, The supply direction of the pressurized fluid and the supply flow rate are controlled according to the operation signals (31, 32, 41, 42). The operation signals 31, 32, 41 and 42 for the high load side control valve 10 and the low load side control valve 20 are input to the pilot ports 11, 12, 13 , ≪ / RTI > 14).

Whether the high load actuator 100 or the low load actuator 200 is divided according to the size of the maximum load to be handled is that the actuator having a large load is a high load actuator and the actuator having a small load is a low load actuator.

If the construction machine is an excavator, for example, the high load actuator 100 may be a boom cylinder and the low load actuator 200 may be a swing motor. In another example, the high load actuator 100 is a boom cylinder and the low load actuator 200 is an arm cylinder And the low load actuator 200 may be a swing motor, for example, as another example, the high load actuator 100 may be a traveling motor and the low load actuator 200 may be a swing motor.

Since the pressure (output) of the hydraulic pump is determined by the pressure of the high-load actuator when a plurality of actuators having different loads are used and connected to a plurality of actuators having different loads, 5) is supplied with the same pressure as the pressure of the high-load actuator, thereby causing energy loss.

That is, a pressure difference equal to the pressure of the high load actuator is supplied to the low load side supply line 5, so that a pressure difference is generated between the pump and the low load actuator. In the low load side control valve 20, Energy loss (eg throttle loss) to lower the pressure to the required pressure. The energy required for operating the hydraulic pump 2 (for example, the fuel of the engine or the power of the motor) is wasted as much as the loss.

Korean Unexamined Patent Publication No. 10-2016-0103152 Korean Unexamined Patent Publication No. 10-2015-0033928 Korean Registered Patent Publication No. 10-0665108 Korean Unexamined Patent Publication No. 10-2016-0051348

As described above, when a plurality of actuators having different loads are connected to one hydraulic pump, energy that is discharged through a low-load actuator can be collected, stored, and reused, thereby saving energy And to provide a hydraulic energy recovery system of the machine.

In order to achieve the above object, a hydraulic control system of a construction machine of the present invention comprises: a hydraulic pump (2) driven by a power source (1); A high load side supply line 4 and a low load side supply line 5 branched in parallel from the main hydraulic line 3 of the hydraulic pump 2 and connected to the high load actuator 100 and the low load actuator 200; The first and second hydraulic lines 101 and 102 are connected to the high load side supply line 4 and the low load side supply line 5 respectively and are connected to the high load actuator 100 and the low load actuator 200, A high load side control valve 10 and a low load side control valve 20 connected to the two hydraulic lines 201 and 202 for controlling the operation of the high load actuator 100 and the low load actuator 200; An axial-pressure hydraulic line 300 branched from one of the first and second hydraulic lines 201 and 202 of the low-load actuator 200 and an accumulator (not shown) provided in the axial- 310); A hydraulic pressure drawing line 400 branched from the hydraulic pressure hydraulic line 300 for drawing the pressure energy stored in the accumulator 310 to the third operating portion 500; ;

A first control valve 330 is provided on a hydraulic line branched from the first and second hydraulic lines 201 and 202 and the hydraulic pressure line 300 is branched, The second control valve 340 is installed in the hydraulic pressure line 300 for the accumulation of hydraulic fluid and the third control valve 510 is installed in the hydraulic pressure line 400 so that the axial pressure signal 51 and the axial pressure energy use signal 52 to the pressure oil tank 7 or to the accumulator 310 through the hydraulic pressure line for accumulation 300 to store the pressure energy And draws the pressure energy stored in the accumulator 310 through the hydraulic lead-out line 400 to be used in the third operation unit 500. [

In the hydraulic energy recovery system of the construction machine according to the present invention, the third operating portion 500 may be an actuator as another operational end of the construction machine except for the high load actuator 100 and the low load actuator 200 .

In the hydraulic energy recovery system of the construction machine according to the present invention, the high load actuator 100 may be a boom cylinder of an excavator, and the low load actuator 200 may be a hydraulic motor for turning the excavator.

In the hydraulic energy recovery system of a construction machine according to the present invention, the third operating portion 500 is a means for assisting the discharge flow rate of the hydraulic pump 2, and the third control portion 500 of the hydraulic drawing- The outlet line 402 of the valve 510 may be connected to the main hydraulic line 3 of the hydraulic pump 2.

In the hydraulic energy recovery system of the construction machine according to the present invention, the third operation unit 500 includes means for assisting driving of the hydraulic pump 2, The hydraulic motor 502 may be installed on the outlet line 402 of the hydraulic pump 510 and the output shaft 502a of the hydraulic motor 502 may be connected to the drive shaft 1a of the hydraulic pump 2 .

In the hydraulic energy recovery system of the construction machine according to the present invention, the operation of recovering and storing the pressure in the accumulator 310 is performed during the combined operation in which the high load actuator 100 and the low load actuator 200 operate simultaneously .

According to the hydraulic control system of the present invention, in a hydraulic circuit of a construction machine in which a plurality of actuators having different loads are used by being connected to one hydraulic pump, an oil pressure line from a low-load actuator of a plurality of actuators to a pressure- The pressure energy of the pressure returning from the low load actuator to the pressure oil tank under the condition that the high load actuator and the low load actuator are used simultaneously is stored in the accumulator while the pressure stored in the accumulator The energy can be used in a separate third operating portion.

Accordingly, it is possible to reduce the throttle loss caused by the pressure difference between the hydraulic pump and the low-load actuator, to store the energy in the accumulator and to use it for other actuators, to assist the flow rate of the hydraulic pump, And the like.

1 is a view showing a hydraulic energy recovery system of a construction machine according to a conventional example in which a plurality of actuators having different loads are connected to one hydraulic pump.
2 is a view showing a hydraulic energy recovery system of a construction machine according to a first embodiment of the present invention.
3 is a view showing a hydraulic energy recovery system of a construction machine according to a second embodiment of the present invention.
4 is a diagram showing a hydraulic energy recovery system of a construction machine according to a third embodiment of the present invention.

Hereinafter, specific embodiments of a hydraulic energy recovery system of a construction machine of the present invention will be described with reference to the accompanying drawings.

2 is a view showing a hydraulic energy recovery system of a construction machine according to a first embodiment of the present invention.

2, the hydraulic energy recovery system for a construction machine according to the present invention includes a hydraulic pump 2 driven by a power source 1, and is connected in parallel from the main hydraulic line 3 of the hydraulic pump 2, Side control valve (not shown) which has an input side connected to the high-load-side supply line 4 and controls the operation of the high-load actuator 100. The high-load- And a high load side control valve 10 connected to an input side of the low load side supply line 5 for controlling the operation of the low load actuator 200.

The high load side control valve 10 and the low load side control valve 20 are provided with a center bypass line 6 and supply hydraulic pressure to the first pressure chambers 100a and 200a of the respective actuators 100 and 200 Or return ports and ports for supplying or returning hydraulic pressure to the second pressure chambers 100b and 200b. The pressurized oil returned from each of the actuators 100 and 200 is sent to the pressurized oil tank 7.

Each port of the high load side control valve 10 is connected to the first and second pressure chambers 100a and 100b of the high load actuator 100 through the first and second hydraulic lines 101 and 102. [

Similarly, each port of the low load side control valve 20 is connected to the first and second pressure chambers 200a and 200b of the low load actuator 200 through the first and second hydraulic lines 201 and 202, respectively.

One hydraulic line among the first and second hydraulic lines 201 and 202 of the low load actuator 200 is branched from the second hydraulic line 202 in the present embodiment, An accumulator 310 for recovering and storing the pressure energy of the pressure oil returned from the low load actuator 200 is installed in the hydraulic pressure hydraulic line 300.

2, the hydraulic pressure hydraulic line 300 is shown as branched from the second hydraulic line 202 connected to the second hydraulic pressure chamber 200b of the low-load actuator 200. However, May be branched from the first hydraulic line 201 connected to the hydraulic chamber 200a.

The high load side control valve 10 and the low load side control valve 20 are each provided with a spool that operates to control the direction and flow amount of the pressurized oil and each of the high load side control valves 10 32, 41, 42 by the operation direction and the operation amount of the operation lever of the driver.

The operation signals 31, 32, 41 and 42 for the high load side control valve 10 and the low load side control valve 20 are input to the pilot ports 11, 12, 13 , ≪ / RTI > 14).

From the hydraulic pressure hydraulic line 300, a hydraulic pressure-drawing line 400 for drawing the pressure energy stored in the accumulator 310 to the third operating portion 500 is branched.

That is, the hydraulic lead-out line 400 is used to take out the pressure energy stored in the accumulator 310 to the third operating part 500 other than the high-load actuator 100 or the low- Hydraulic line.

For example, the third actuating part 500 may be an actuator as another actuating end of the construction machine except for the high-load actuator 100 and the low-load actuator 200.

On the other hand, the high-load actuator 100 may be a boom cylinder of an excavator, the low-load actuator 200 may be a hydraulic motor for pivoting of an excavator, and the third operating portion 500 may be an arm cylinder, Cylinder, or a hydraulic motor for driving.

The second hydraulic line 202, the hydraulic pressure line for hydraulic pressure 300 and the hydraulic pressure line 400 are selectively opened and closed in accordance with the axial pressure signal 51 and the axial pressure energy use signal 52 A first control valve 330, a second control valve 340, and a third control valve 510 are installed.

That is, the first control valve 330 is installed in the hydraulic line downstream of the branch point JP1 of the hydraulic pressure hydraulic line 300, that is, the second hydraulic line 202) Pressure hydraulic line 300, and the third control valve 510 is installed in the hydraulic-pressure line 400.

The first to third control valves 330, 340, and 510 supply the pressure oil returned from the low load actuator 200 to the pressure oil tank 7 in accordance with the accumulation pressure signal 51 and the accumulation energy use signal 52, (Third) pressure energy stored in the accumulator 310, (3) pressure energy stored in the accumulator 310, (4) pressure energy stored in the accumulator 310, The energy is controlled to be drawn out through the hydraulic lead-out line 400 and used for the third operation part 500.

The axial pressure signal 51 is configured to be delivered when a pressure is to be stored in the accumulator 310 by the controller. The pressure-accumulating signal 51 is supplied to the first pressure chambers 100a and 200a of the high-load actuator 100 and the low-load actuator 200 when the high-load actuator 100 and the low-load actuator 200 operate simultaneously, So that the hydraulic pressure is simultaneously supplied to the hydraulic pump.

The accumulation energy use signal 52 is configured to be delivered when the pressure stored in the accumulator 310 is used by the controller in the third operation unit 500.

The control valves 330, 340, and 510 are in the state shown in FIGS. 2 to 4 at all times. That is, the state shown in FIGS. 2 to 4 is the initial state, and when the control signal 51 or 52 is applied to each of the control terminals 331, 341, and 511, it moves in the opposite direction.

That is, the first control valve 320 is a normally open valve (Normally Opened V / V), and only when the axial pressure signal 51 is inputted, that is, when a signal for storing energy in the accumulator 310 is input Only closed.

The second control valve 340 is normally closed valve (Normally Closed V / V) and is opened only when the axial pressure signal 51 is inputted.

The third control valve 510 is opened only when the axial pressure energy use signal 52 is input as the normally closed valve. The third control valve 510 may be a proportional control valve.

In the present invention, the operation of recovering and storing the pressure in the accumulator 310 is configured to be performed when the high-load actuator 100 and the low-load actuator 200 are used at the same time.

That is, the pressure (output) of the hydraulic pump 2 is supplied in accordance with the pressure of the high load actuator 100, so that a pressure difference is generated between the hydraulic pump 2 and the low load actuator 200, When energy loss (for example, throttle loss) for lowering the pressure to a required pressure is generated in the low load actuator 200, the energy to be lost is induced in the accumulator 310 and stored.

This operation will be described in more detail with reference to FIG. It is assumed that the two actuators 100 and 200 are used simultaneously in a complex operation. For example, if the high load actuator 100 is a boom cylinder of an excavator and the low load actuator 200 is a swing cylinder, in the so-called " loading operation " in which the excavator dug soil and transfer it to a truck, The hydraulic motor for revolving is operated simultaneously to rotate the upper revolving body.

The operation signal 31 of the high load actuator 100 is transmitted to the pilot port of the high load side control valve 10 through the operation of the operating lever of the driver 11 and the operation signal 41 of the low load actuator 200 is applied through the pilot port 21 of the low load side control valve 20 so that the high load side control valve 10 and the low load side control valve 10, (20) are all switched to the left.

Therefore, the pressurized oil discharged from the hydraulic pump 2 flows into the first pressure chamber 100a of the high-load actuator 100 through the high-load-side control valve 10, while the low- Flows into the first hydraulic chamber 200a of the actuator 200, whereby the high-load actuator 100 and the low-load actuator 200 simultaneously move to the right. Therefore, the boom cylinder of the excavator rises and the orbiting motor rotates.

Since the discharge pressure of the hydraulic pump 2 is adjusted to the high-load actuator 100 having a large load, the high-load actuator 100 is supplied with pressure oil as high as that pressure. At this time, in the control unit, the axial pressure signal 51 is supplied so that the first control valve 330 is actuated upwardly in the drawing by the axial pressure signal 51 and the second control valve 340 is operated to the right So that the second hydraulic line 202 is closed and only the hydraulic line 300 for the hydraulic pressure is opened.

Therefore, the pressure oil discharged from the second hydraulic chamber 200b of the low-load actuator 200 (that is, returned to the pressure oil tank 7) acts on the accumulator 310 so that the discharge pressure of the hydraulic pump 2 The pressure energy equivalent to the differential pressure of the working side pressure of the low load actuator 200 is stored in the accumulator 310. [

For example, in the boom up (boom cylinder lift) and revolving composite operation, the hydraulic pressure required for boom up is 200 bar, the pressure required for the swing motor is 80 bar, the return pressure of the low load actuator 200 is 10 bar If pressure is not applied, the pressure of 110 bar (= 200-80-10 bar) will be lost.

However, as in the present invention, when the accumulator 310 is provided on the side of the second hydraulic line 202 on the side of the second hydraulic chamber 200b of the low-load actuator 200 to increase the back pressure, The pressure of the oil pressure chamber 200a can be further increased and the throttle loss energy can be stored in the accumulator 310. [

For example, if the storage pressure of the accumulator 310 is 100 bar, a back pressure of 100 bar is applied to the low load actuator 200. In this case, a pressure of 180 bar (= 100 + 80 bar) is required for the first oil pressure chamber 200a and a pressure of 180 bar is supplied from the oil pressure pump 2 so that the throttle loss pressure is only 20 bar (= 200-180 bar) . At this time, the pressure energy of 100 bar is stored in the accumulator 310. As the pressure energy is stored in the accumulator 310, the thrust loss pressure decreases as the pressure of the accumulator 310 rises.

In FIG. 2, 'SV1', 'SV2', and 'SV3' are reverse flow prevention valves that prevent backflow of pressurized fluid.

Next, the operation of using the pressure recovered (stored) in the accumulator 310 will be described.

Referring to Fig. 2, the use of the pressure stored in the accumulator 310 is accomplished by passing the accumulation energy use signal 52 from the controller.

The accumulation energy use signal 52 is applied to the third control valve 510 so that the third control valve 510 is switched in the opening direction to open the hydraulic lead-out line 400.

Accordingly, the pressure energy stored in the accumulator 310 is transmitted to the third operation unit 500 through the hydraulic line 400 and used.

Next, Fig. 3 shows a hydraulic energy recovery system of a construction machine according to a second embodiment of the present invention.

In the embodiment shown in Fig. 3, only the configuration of the third operating section 500 described in Fig. 2 is different, and the remaining configuration is the same.

Referring to FIG. 3, the third operating portion 500 is used as a means for assisting the discharge flow rate of the hydraulic pump 2 in particular.

That is, the outlet line 402 of the third control valve 510 of the hydraulic line 400 is connected to the main hydraulic line 3 of the hydraulic pump 2.

According to this, the pressure stored in the accumulator 310 can act on the main hydraulic line 3 through the hydraulic line 400 to assist the flow rate of the hydraulic pump 2, and to control the pump discharge flow rate Thereby reducing the load on the engine 1 and lowering the fuel consumption rate.

In FIG. 3, 'SV5' is a backflow prevention valve.

Next, Fig. 4 shows a hydraulic energy recovery system of a construction machine according to a third embodiment of the present invention.

The embodiment shown in Fig. 4 differs from that of the third operating portion 500 shown in Figs. 2 and 3 only in the rest of the configuration.

Referring to FIG. 4, the third operating portion 500 is used as a means for assisting the driving of the hydraulic pump 2 in particular.

That is, the hydraulic motor 502 is installed on the outlet line 402 of the third control valve 510 of the hydraulic drawing-out line 400, and the output shaft 502a of the hydraulic motor 502 is connected to the hydraulic pump 502 And connected to the drive shaft 1a.

The pressure energy stored in the accumulator 310 drives the hydraulic motor 502 and the output of the hydraulic motor 502 drives the drive shaft 1a of the hydraulic pump 2 through the output shaft 502a It is possible to assist the driving of the hydraulic pump 2, thereby reducing the load on the engine 1 and lowering the fuel consumption rate.

The foregoing is a description of certain preferred embodiments of the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, .

1: engine
1a: drive shaft
2: Hydraulic pump
3: Main hydraulic line
4: High load side supply line
5: Low load side supply line
6: Center bypass line
7: Pressure oil tank
10: High load side control valve
11, 12, 21, 22, 331, 321, 511: Pilot port
20: Low load control valve
31, 32, 41, 42: Operation signal
51: Axial pressure signal
52: Signal used for accumulating energy
100: High load actuator
100a, 200a: first pressure chamber
100b, 200b: a second pressure chamber
101, 201: first hydraulic line
102, 202: second hydraulic line
300: Axial pressure hydraulic line
310: Accumulator
330: first control valve
331, 341, 511: control stage
340: second control valve
400: Hydraulic drawing line
500: third operating portion
502: Hydraulic motor
502a: Output shaft
510: third control valve

Claims (6)

A hydraulic pump 2 driven by the power source 1;
A high load side supply line 4 and a low load side supply line 5 branched in parallel from the main hydraulic line 3 of the hydraulic pump 2 and connected to the high load actuator 100 and the low load actuator 200;
A high load side control valve 10 and a low load side control valve 10 connected to the high load side supply line 4 and the low load side supply line 5 for controlling the operation of the high load actuator 100 and the low load actuator 200, (20);
An accumulator 310 installed in the hydraulic pressure line 300 for branching from the hydraulic line of any one of the first and second hydraulic lines 201 and 202 of the low load actuator 200; And
A hydraulic pressure drawing line 400 branched from the hydraulic pressure hydraulic line 300 for drawing the pressure energy stored in the accumulator 310 to the third actuating part 500; / RTI >
A first control valve 330 is provided on a hydraulic line branched from the first and second hydraulic lines 201 and 202 and the hydraulic pressure line 300 is branched, The second control valve 340 is installed in the hydraulic pressure line 300 for the accumulation of hydraulic fluid and the third control valve 510 is installed in the hydraulic pressure line 400 so that the axial pressure signal 51 and the axial pressure energy use signal 52 to the pressure oil tank 7 or to the accumulator 310 through the hydraulic pressure line for accumulation 300 to store the pressure energy And draws the pressure energy stored in the accumulator (310) through the hydraulic lead-out line (400) to be used in the third operation part (500). The method of claim 1,
Wherein the third operating portion (500) is an actuator as another operational end of the construction machine except for the high load actuator (100) and the low load actuator (200). The method of claim 1,
The high load actuator 100 is a boom cylinder of an excavator,
Wherein the low load actuator (200) is a hydraulic motor for turning the excavator. The method of claim 1,
The third operating portion 500 is a means for assisting the discharge flow rate of the hydraulic pump 2 so that the outlet line 402 of the third control valve 510 of the hydraulic drawing- And a main hydraulic line (3) of the pump (2). The method of claim 1,
The third operating portion 500 is a means for assisting driving of the hydraulic pump 2 and includes a hydraulic motor (not shown) connected to the outlet line 402 of the third control valve 510 of the hydraulic drawing- 502) and the output shaft (502a) of the hydraulic motor (502) is connected to the drive shaft (1a) of the hydraulic pump (2). The method of claim 1,
Wherein the operation of recovering and storing the pressure in the accumulator (310) is configured to be performed during a combined operation in which the high load actuator (100) and the low load actuator (200) operate simultaneously.

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