JP2021063566A - Hydraulic control device and construction machine - Google Patents

Abstract

To provide a hydraulic control device that can simplify a configuration of a hydraulic system for supporting electric control, and to provide a construction machine.SOLUTION: A hydraulic control device 5 includes: a high-pressure selection unit 10 for selecting an oil passage with higher pressure from two oil passages 8, 9 corresponding to bidirectional drive system included in a hydraulic drive unit 200 that is driven by hydraulic pressure; and a direction switching unit 20 including a switching valve 20C for switching an operation direction of the hydraulic drive unit in accordance with an operation direction corresponding to the oil passage with higher pressure.SELECTED DRAWING: Figure 3

Description

The present invention relates to a hydraulic control device and a construction machine.

Proportional valves for controlling construction machinery such as power shovels are provided separately on the push side and pull side, and along with this, two proportional valve drive circuits are also provided (see, for example, Patent Document 1). ). By the way, when a construction machine such as a pure hydraulic power shovel is electrically controlled, an electromagnetic proportional pressure reducing valve is used for hydraulic control.

Japanese Unexamined Patent Publication No. 2019-052702

When trying to electrically control an existing flood control system, it is necessary to install a pressure detection sensor and an electromagnetic proportional pressure reducing valve for hydraulic control for each of the two operating hydraulic systems on the boom and arm, which are the push side and the pull side. The power shovel, which has a small space, required a major remodeling.

An object of the present invention is to provide a hydraulic control device and a construction machine capable of simplifying the configuration of a hydraulic system corresponding to electrical control.

The hydraulic control device according to one aspect of the present invention includes a high-pressure selection unit that selects the oil passage having the higher pressure among the two oil passages corresponding to the two-way drive system of the hydraulic drive unit driven by the flood control. A direction switching unit having a switching valve for switching the operating direction of the hydraulic drive unit according to the operating direction corresponding to the oil passage having the higher pressure.

The hydraulic control device according to one aspect of the present invention has a high-pressure selection unit that selects the oil passage having the higher pressure among the two oil passages to which the operating pressure is output, and an oil passage selected by the high-pressure selection unit. A direction switching unit that outputs the operating pressure is provided.

With this configuration, in a device that is hydraulically controlled, two systems of hydraulic circuits are normally provided corresponding to the operating directions in two directions, whereas the high-pressure selection unit applies pressure according to the operation. The higher oil passage is selected, and the switching valve switches the operating direction of the hydraulic drive unit in the direction according to the operation, so the hydraulic drive unit can be controlled by one system of hydraulic circuit, simplifying the configuration. can do.

In the above configuration, the high pressure selection unit may include a high pressure selection valve that supplies the operating pressure generated in the oil passage from the oil passage having the higher pressure among the two oil passages.

With this configuration, the high-pressure selection valve selects the oil passage having the higher pressure, so that the flood control drive unit can be easily controlled by one system of the flood control circuit.

With the above configuration, the flood control device may include a proportional valve that adjusts and outputs the operating pressure output from the high pressure selection valve.

With this configuration, the proportional valve uses the hydraulic oil output from the high-pressure selection valve for control, so there is no need to install a separate hydraulic pump for the proportional valve, and when the hydraulic control device is electrified. The configuration of can be simplified.

In the above configuration, the direction switching unit is a switching valve that switches the operating direction of the hydraulic drive unit when each of the drive systems in the two directions is connected to both ends and a pressure difference between the two oil passages occurs. You may be prepared.

With this configuration, the switching valve can supply hydraulic oil to the oil passages corresponding to the raising and lowering directions of the boom, etc., so that some piping can be omitted and the configuration is simplified. be able to.

In the above configuration, the flood control device may include a pressure boosting unit that boosts the operating pressure output from the high pressure selection valve and inputs it to the proportional valve.

With this configuration, the pressure booster boosts the operating pressure required to control the proportional valve, so the operating pressure output from the high-pressure selective valve can be used to control the proportional valve.

With the above configuration, the hydraulic control device may include a control unit that adjusts the pressure of the pressure increasing unit to an arbitrary pressure value.

With this configuration, the control unit can change the pressure increase value of the pressure booster unit and perform control according to the intention of the operator.

In the above configuration, the hydraulic control device discharges the excess hydraulic oil of the proportional valve connected to the low pressure selection unit and the low pressure selection unit that selects the oil passage having the lower pressure from the two oil passages. It may be provided with a drain oil passage to be provided.

With this configuration, the drain oil passage of the proportional valve can be used as the oil passage with the lower pressure of the two oil passages, and the drain oil passage normally provided in the proportional valve can be omitted to configure the device. It can be simplified.

The hydraulic control device according to one aspect of the present invention includes a high-pressure selection unit that selects the oil passage having the higher pressure among the two oil passages corresponding to the two-way drive system of the hydraulic drive unit driven by hydraulic pressure. A direction switching unit having a switching valve for switching the operating direction of the hydraulic drive unit according to the operating direction corresponding to the oil passage having the higher pressure, and the high pressure selection unit provided in the two oil passages. A high-pressure selection valve that supplies the operating pressure generated in the oil passage from the oil passage having the higher pressure, and the two oil passages provided at the direction switching portion and each of the drive systems in the two directions are connected to both ends. A switching valve that switches the operating direction of the hydraulic drive unit when a pressure difference occurs, a proportional valve that adjusts and outputs the operating pressure output from the high-pressure selection valve, and an output from the high-pressure selection valve. A pressure boosting unit that boosts the operating pressure and inputs it to the proportional valve, a control unit that adjusts the pressure of the pressure boosting unit to an arbitrary pressure value, and an oil passage that has the lower pressure of the two oil passages. It is provided with a low-pressure selection unit for selecting a low-pressure selection unit and a drain oil passage connected to the low-pressure selection unit to discharge excess hydraulic oil of the proportional valve.

With this configuration, the direction is switched according to the operation, and the hydraulic oil controlled from the hydraulic source through the electromagnetic proportional pressure reducing valve can be input to the boom so that the switching valve operates in the direction according to the operation. It can simplify the hydraulic circuit.

The construction machine may include the hydraulic control device having the above configuration.

With such a configuration, the hydraulic control device of the construction machine can be simplified.

According to the present invention, it is possible to simplify the configuration of the hydraulic system corresponding to the electric control.

The schematic block diagram of the construction machine in embodiment of this invention. The block diagram of the hydraulic system in embodiment of this invention. The block diagram of the hydraulic control device in embodiment of this invention. The block diagram of the modification of the hydraulic control device in embodiment of this invention.

Next, an embodiment of the present invention will be described with reference to the drawings.

(Construction machinery)
As shown in FIG. 1, the construction machine 100 is, for example, a hydraulic excavator. The construction machine 100 includes a swivel body 101 and a traveling body 102. The swivel body 101 is provided on the traveling body 102 so as to be swivelable. The swivel body 101 is provided with a hydraulic system 1.

The swivel body 101 swings to the cab 103 on which the operator can board, the boom 104 whose one end is swingably connected to the cab 103, and the other end (tip) of the boom 104 on the opposite side of the cab 103. It includes an arm 105 whose one end is freely connected, and a bucket 106 which is swingably connected to the other end (tip) of the arm 105 on the opposite side of the boom 104. Further, a hydraulic system 1 is provided in the cab 103. The hydraulic oil supplied from the hydraulic system 1 drives the cab 103, the boom 104, the arm 105, and the bucket 106.

(Flood system)
As shown in FIG. 2, the hydraulic system 1 operates with an engine 2 as a drive source, a hydraulic pump 3 driven by the engine 2, and a plurality of actuators 4 driven by hydraulic oil from the hydraulic pump 3. A hydraulic control device 5 that controls the operation of a plurality of actuators 4 in response to an operation signal from the unit 6, a tank T that stores hydraulic oil, an oil cooler C that cools hydraulic oil, and a relief valve for pressure adjustment. With S.

The engine 2 is an internal combustion engine using gasoline or diesel fuel. The engine 2 includes an output shaft 2A, and the output shaft 2A is connected to a hydraulic pump 3. An oil passage P is connected to the hydraulic pump 3. The hydraulic pump 3 is driven by the output shaft 2A to circulate hydraulic oil in the oil passage P. A flood control device 5 is connected to the oil passage P. The engine 2 may be an electric motor or the like connected to a capacitor without using an internal combustion engine.

A plurality of actuators 4 are connected to the hydraulic control device 5 via a branched oil passage P. The hydraulic control device 5 has a plurality of control valves 5B, and supplies the hydraulic oil of the hydraulic oil flowing through the oil passage P from the control valve to the actuator 4 in response to an operation signal from the operation unit 6. The hydraulic control device 5 constitutes a multi-valve continuous block including a plurality of control valves 5B. The plurality of actuators 4 drive a plurality of hydraulic drive units 200 such as a cab 103, a boom 104, an arm 105, and a bucket 106.

Next, the hydraulic control device 5 will be described. The hydraulic control device 5 includes an operation signal circuit 5A that controls the control valve 5B in response to an operation signal from the operation unit 6. The conventional hydraulically controlled construction machine 100 is driven by having two systems of hydraulic circuits corresponding to two-way control such as turning of the cab 103 and raising / lowering (pushing / pulling) of the boom 104, the arm 105, and the bucket 106. It is controlled by the system.

The operation signal circuit 5A is a hydraulic circuit that simplifies the two hydraulic circuits and is configured into one system and is controlled by one electromagnetic proportional valve. The push-side and pull-side hydraulic circuits are not used at the same time in the hydraulic circuit for the two-way drive system. Therefore, the device can be simplified by switching the push-side and pull-side circuits with one electromagnetic proportional valve. Hereinafter, a configuration for driving the boom 104 will be described as a typical example.

As shown in FIG. 3, the operation signal circuit 5A includes a high-pressure selection unit 10 connected to an oil passage 7 connected to the operation unit 6, a hydraulic sensor 12 for detecting the oil pressure of the high-pressure selection unit 10, and a hydraulic sensor. A control unit 14 connected to 12, a driver 16 controlled by the control unit 14, a pressure boosting unit 22 connected to the high pressure selection unit 10 to supply hydraulic oil, and an electromagnetic drive driven based on the signal of the driver 16. A proportional valve 18, a direction switching unit 20 connected to the electromagnetic proportional valve 18, and a low pressure selection unit 24 connected to the oil passage 7 are provided.

The operation unit 6 has an operation lever, and for example, the control amount of the boom 104 is adjusted in conjunction with the operation amount such as the angle at which the operation lever is tilted. An oil passage 7 for distributing hydraulic oil according to the amount of operation is connected to the operation unit 6. The operating unit 6 adjusts the operating pressure generated by the flow of hydraulic oil in the oil passage 7. The oil passage 7 is a part of the oil passage P and is a pipe for hydraulic oil for controlling the control valve 5B. The oil passage 7 is provided with two oil passages corresponding to the two-way drive system of the hydraulic drive unit 200. The oil passage 7 includes, for example, a first oil passage 8 connected to a drive system in the direction of raising the boom 104, and a second oil passage 9 connected to a drive system in the direction of lowering the boom 104.

In the first oil passage 8, when the operation lever is tilted in the upward direction in the operation unit 6, hydraulic oil circulates inside the pipe according to the amount of operation, and the pressure becomes higher than that of the second oil passage 9. In the second oil passage 9, when the operation lever is tilted in the downward direction in the operation unit 6, hydraulic oil circulates inside according to the amount of operation, and the pressure becomes higher than that of the first oil passage 8. A high pressure selection unit 10 is connected to the first oil passage 8 and the second oil passage 9. A low-pressure selection unit 24, which will be described later, is connected to the first oil passage 8 and the second oil passage 9.

The high pressure selection unit 10 selects the oil passage on the high pressure side of the first oil passage 8 and the second oil passage 9. For example, when the operation unit 6 is operated in the upward direction, hydraulic oil flows through the first oil passage 8, and the pressure of the first oil passage 8 becomes relatively higher than that of the second oil passage 9. When the operation unit 6 operates in the downward direction, hydraulic oil flows through the second oil passage 9, and the pressure of the second oil passage 9 becomes relatively higher than that of the first oil passage 8. The high pressure selection unit 10 inputs the hydraulic oil from the selected oil passage on the high pressure side to the pressure boosting unit 22.

The high-pressure selection unit 10 includes, for example, a first check valve 10A (high-pressure selection valve) connected to the first oil passage 8 side and a second check valve 10B (high-pressure selection valve) connected to the second oil passage 9 side. And. When the pressure on the first oil passage 8 side becomes high, the first check valve 10A inputs hydraulic oil from the first oil passage 8 and supplies operating pressure. When the pressure on the second oil passage 9 side becomes high, the second check valve 10B inputs hydraulic oil from the second oil passage 9 and supplies operating pressure. The oil pressure of the hydraulic oil input from the high pressure selection unit 10 is detected by the oil pressure sensor 12.

The oil pressure sensor 12 outputs the detected value of the detected hydraulic oil pressure of the hydraulic oil to the control unit 14. The control unit 14 is composed of a CPU (Central Processing Unit). The control unit 14 calculates the control amount of the proportional valve 18 based on the detected value acquired from the oil pressure sensor 12. The control unit 14 controls the driver 16 based on the calculated calculated value. The control unit 14 causes the driver 16 to output a signal based on the current according to the calculated value. That is, the driver 16 outputs a current value corresponding to the hydraulic pressure of the hydraulic oil to the proportional valve 18.

The proportional valve 18 is, for example, an electromagnetic proportional pressure reducing valve that adjusts the pressure of hydraulic oil according to a current value given for control and outputs the pressure. The proportional valve 18 has a pressure adjusting unit that adjusts the pressure of the hydraulic oil. The proportional valve 18 inputs the hydraulic oil adjusted to a predetermined oil pressure value (pilot oil pressure) for control, and outputs the hydraulic oil whose pressure is adjusted by the pressure adjusting unit.

When the proportional valve 18 is used under normal conditions, it is necessary to input hydraulic oil higher than the output oil pressure for operation, and a drain circuit that returns the hydraulic oil discharged by the excess pressure of the input hydraulic oil to the tank T. Is required. The proportional valve 18 according to the present embodiment is provided with a drain oil passage 18B, which will be described later, as a substitute for the drain circuit while inputting the hydraulic oil boosted by the pressure boosting unit 22.

The pressure boosting unit 22 increases the operating pressure output from the high pressure selection unit 10 by about 1.5 times to the oil pressure value used for the pilot oil pressure. The pressure boosting unit 22 inputs the operating pressure boosted to the oil pressure value of the pilot oil pressure from the input unit 22A to the proportional valve 18. The pressure boosting unit 22 may be configured to adjust the operating pressure to an arbitrary pressure value under the control of the control unit 14.

As described above, the hydraulic control device 5 can omit the hydraulic circuit and the device used for generating the operating pressure by providing the pressure boosting unit 22 in the hydraulic circuit. The proportional valve 18 inputs the pressure-adjusted operating pressure from the output unit 18A to the direction switching unit 20.

The direction switching unit 20 is connected to the first oil passage 8 and the second oil passage 9, and switches the output direction of the hydraulic oil input from the proportional valve 18 in conjunction with the operation of the operation unit 6. The direction switching unit 20 includes a switching valve 20C having a sleeve (not shown) and a spool inserted into the sleeve (not shown).

The switching valve 20C is connected to both ends of a drive system in two directions, that is, a first oil passage 8 and a second oil passage 9. When the pressure difference between the drive systems in the two directions acts, the switching valve 20C moves the spool from the higher pressure direction to the lower pressure direction and outputs the hydraulic oil of the drive system having the higher pressure to output the hydraulic oil of the drive system of the higher pressure side. Switch the operating direction. That is, the switching valve 20C moves the spool by the hydraulic oil input from the first oil passage 8 or the second oil passage 9, and switches the output direction of the hydraulic oil input from the proportional valve 18 in the opposite direction.

For example, when hydraulic oil is input from the first oil passage 8 in conjunction with the operation of the operation unit 6, the direction switching unit 20 uses the hydraulic oil input from the proportional valve 18 in the oil passage 20A in the direction in which the boom 104 rises. Output from. In the direction switching unit 20, for example, when hydraulic oil is input from the second oil passage 9 in conjunction with the operation of the operation unit 6, the oil passage 20B in the direction in which the boom 104 lowers the hydraulic oil input from the proportional valve 18. Output from. The direction switching unit 20 allows the hydraulic control device 5 to move the boom 104 in a direction corresponding to the operation of the operation unit 6 by one system of hydraulic circuits.

Next, the drain of the proportional valve 18 and the pressure boosting unit 22 will be described.

As described above, the proportional valve 18 is an electromagnetic proportional pressure reducing valve. Normally, in order to control the electromagnetic proportional pressure reducing valve, in addition to the oil passages of the input unit 22A for inputting the hydraulic oil adjusted to the pilot oil pressure and the output unit 18A for outputting the hydraulic oil, the operation is discharged with excess pressure. An oil channel for the oil drain is required. The proportional valve 18 of the embodiment is provided with a drain oil passage 18B, and either one of the first oil passage 8 and the second oil passage 9 connected to the drain oil passage 18B is used as the drain.

The drain oil passage 18B is connected to the downstream side of the first oil passage 8 and the second oil passage 9 via the low pressure selection unit 24. The low pressure selection unit 24 selects the oil passage on the low pressure side of the first oil passage 8 and the second oil passage 9. For example, when the operation unit 6 operates in the upward direction, hydraulic oil flows through the first oil passage 8, and the relative pressure of the first oil passage 8 becomes higher than that of the second oil passage 9. At this time, the low pressure selection unit 24 selects the second oil passage 9 on the low pressure side. When the operation unit 6 operates in the downward direction, hydraulic oil flows through the second oil passage 9, and the pressure of the second oil passage 9 becomes higher than that of the first oil passage 8. At this time, the low pressure selection unit 24 selects the first oil passage 8 on the low pressure side. The low pressure selection unit 24 discharges the hydraulic oil discharged by the excess pressure in the proportional valve 18 to the selected low pressure side oil passage.

The low-pressure selection unit 24 includes, for example, a third check valve 24A connected to the first oil passage 8 side and a fourth check valve 24B connected to the second oil passage 9 side. The third check valve 24A discharges hydraulic oil from the proportional valve 18 when the pressure on the first oil passage 8 side becomes low. The fourth check valve 24B discharges hydraulic oil from the proportional valve 18 when the pressure on the second oil passage 9 side becomes low.

The first oil passage 8 and the second oil passage 9 are used for a pair of operations for raising or lowering the boom 104, and are not used at the same time. Therefore, of the first oil passage 8 or the second oil passage 9, the unused side oil passage has a structure in which the oil for command is released to the drain in order to promptly release the oil for command. With such a structure, the flood control device 5 is configured so that it is not necessary to add a drain circuit by using the oil passages on the unused side of the two systems as drains.

[Modification example]
The proportional valve 18 may be feedback-controlled so that the pressure of the hydraulic oil to be output is adjusted based on the hydraulic pressure of the hydraulic oil to be output. In the following description, the same names and reference numerals will be used for the same configurations as those in the above embodiment, and duplicate description will be omitted as appropriate.

As shown in FIG. 4, the hydraulic control device 5 includes a hydraulic sensor 30 and detects the pressure of the hydraulic oil output from the proportional valve 18. The oil pressure sensor 30 outputs the detected value of the detected hydraulic oil pressure to the control unit 14. The control unit 14 calculates to adjust the control amount of the proportional valve 18 based on the detection value acquired from the oil pressure sensor 30 in addition to the detection value acquired from the oil pressure sensor 12.

Based on the detected value acquired from the oil pressure sensor 30, the control unit 14 reduces the pressure of the hydraulic oil output from the proportional valve 18 when the pressure of the hydraulic oil output from the proportional valve 18 is higher than the set value. When the pressure of the hydraulic oil output from the proportional valve 18 is lower than the set value, the control amount of the proportional valve 18 is calculated so as to increase the pressure of the hydraulic oil output from the proportional valve 18.

As described above, according to the hydraulic control device 5, the hydraulic circuit composed of two systems can be controlled by one system by using the proportional valve 18 and the direction switching unit 20, and the device configuration is simplified. be able to. According to the hydraulic control device 5, the pilot oil pressure for controlling the proportional valve 18 is generated by the pressure boosting unit 22, so that the hydraulic circuit for generating the pilot oil pressure can be omitted. Further, according to the hydraulic control device 5, the drain pressure of the proportional valve 18 is set to the oil passage on the low pressure side by providing the low pressure selection unit 24 for selecting the low pressure side of the first oil passage 8 or the second oil passage 9. It can be missed and the drain circuit can be omitted to simplify the device configuration.

The present invention is not limited to the above-described embodiment, and includes various modifications to the above-described embodiment without departing from the spirit of the present invention. For example, in the above-described embodiment, the case where the construction machine 100 is a hydraulic excavator has been described. However, the present invention is not limited to this, and the above-mentioned hydraulic control device 5 can be adopted in various construction machines.

1 ... Hydraulic system, 2 ... Engine, 2A ... Output shaft, 3 ... Hydraulic pump, 4 ... Actuator, 5 ... Hydraulic control device, 5A ... Operation signal circuit, 5B ... Multiple valves, 6 ... Operation unit, 7 ... Oil passage , 8 ... 1st oil passage, 9 ... 2nd oil passage, 10 ... high pressure selection unit, 10A ... 1st check valve, 10B ... 2nd check valve, 12 ... hydraulic sensor, 14 ... control unit, 16 ... driver, 18 ... Proportional valve, 18A ... Output unit, 18B ... Drain oil passage, 20 ... Direction switching unit, 20A ... Oil passage, 20B ... Oil passage, 20C ... Switching valve, 22 ... Pressure booster, 22A ... Input unit, 24 ... Low pressure Selection part, 24A ... 3rd check valve, 24B ... 4th check valve, 30 ... Hydraulic sensor, 100 ... Construction machine, 101 ... Swing body, 102 ... Running body, 103 ... Cab, 104 ... Boom, 105 ... Arm, 106 ... Bucket, 200 ... Hydraulic drive unit, C ... Oil cooler, P ... Oil passage, S ... Relief valve, T ... Tank

Claims (10)

A high-pressure selection unit that selects the oil passage with the higher pressure from the two oil passages corresponding to the two-way drive system of the hydraulic drive unit driven by flood control,
A direction switching unit having a switching valve for switching the operating direction of the hydraulic drive unit according to the operating direction corresponding to the oil passage having the higher pressure is provided.
Hydraulic control device. A high-pressure selection unit that selects the oil channel with the higher pressure from the two oil channels that output the operating pressure,
A direction switching unit that outputs the operating pressure to the oil passage selected by the high pressure selection unit is provided.
Hydraulic control device. The high-pressure selection unit includes a high-pressure selection valve that supplies the operating pressure generated in the oil passage from the oil passage having the higher pressure among the two oil passages.
The hydraulic control device according to claim 1 or 2. A proportional valve that adjusts and outputs the operating pressure output from the high-pressure selection valve is provided.
The hydraulic control device according to claim 3. The direction switching unit includes a switching valve that switches the operating direction of the hydraulic drive unit when each of the drive systems in the two directions is connected to both ends and a pressure difference between the two oil passages occurs.
The hydraulic control device according to claim 1. It is provided with a pressure boosting unit that boosts the operating pressure output from the high pressure selection valve and inputs it to the proportional valve.
The hydraulic control device according to claim 4. A control unit for adjusting the pressure of the pressure boosting unit to an arbitrary pressure value is provided.
The hydraulic control device according to claim 6. A low-pressure selection unit that selects the oil channel with the lower pressure from the two oil channels,
A drain oil passage which is connected to the low pressure selection unit and discharges excess hydraulic oil of the proportional valve is provided.
The hydraulic control device according to claim 7. A high-pressure selection unit that selects the oil passage with the higher pressure from the two oil passages corresponding to the two-way drive system of the hydraulic drive unit driven by flood control,
A direction switching unit having a switching valve for switching the operating direction of the hydraulic drive unit according to the operating direction corresponding to the oil passage having the higher pressure, and a direction switching unit.
A high-pressure selection valve provided in the high-pressure selection unit and supplying the operating pressure generated in the oil passage from the oil passage having the higher pressure among the two oil passages.
A switching valve provided in the direction switching unit, in which each of the drive systems in the two directions is connected to both ends and the operating direction of the hydraulic drive unit is switched when a pressure difference between the two oil passages occurs.
A proportional valve that adjusts and outputs the operating pressure output from the high-pressure selection valve,
A pressure booster that boosts the operating pressure output from the high pressure selection valve and inputs it to the proportional valve.
A control unit that adjusts the pressure of the pressure booster to an arbitrary pressure value, and
A low-pressure selection unit that selects the oil channel with the lower pressure from the two oil channels,
A drain oil passage which is connected to the low pressure selection unit and discharges excess hydraulic oil of the proportional valve is provided.
Hydraulic control device. A construction machine including the hydraulic control device according to any one of claims 1 to 9.

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