JP2008128107A - Output control device for working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an output control device for an working machine capable of increasing pump input torque greater than before in a specific work during which load acting on an engine gets high while maintaining matching of engine output torque and pump input torque. <P>SOLUTION: A hydraulic excavator provided with a variable displacement hydraulic pressure pump 11 driven by an engine 1 equipped with a turbocharger 4, and a pump input torque control means, has a structure provided with a supercharging pressure control means including a supercharging pressure control valve 22 controlling supercharging pressure higher than before when work is detected as heavy excavation work by a specific work detection means detecting heavy excavation work during which load acting on the engine 1 gets heavy, and a pump input torque changing means changing pump input torque controlled by the pump input torque control means to be higher according to supercharging pressure controlled to be higher by the supercharging pressure control means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is provided in a working machine such as a hydraulic excavator having an engine and a variable displacement hydraulic pump driven by the engine, and outputs the working machine that realizes matching between the engine output torque and the pump input torque. The present invention relates to a control device.

As this type of conventional output control device, that is, a torque control device of a variable displacement hydraulic pump, for example, there is one disclosed in Patent Document 1. This conventional technique uses the atmospheric pressure and the fuel injection amount of the engine as parameters, obtains the fuel injection amount corresponding to the atmospheric pressure from the relationship between the atmospheric pressure and the fuel injection amount, and further determines the fuel injection amount and the inclination of the variable displacement hydraulic pump. The tilt angle corresponding to the fuel injection amount obtained as described above is obtained from the relationship with the turn angle, and the tilt angle corresponding to the obtained engine output torque according to the engine speed is matched. The control signal to be output is output from the controller to the regulator.
JP 2003-176802 A

  In the above-described conventional technology, for example, when the work machine is a hydraulic excavator, it is possible to achieve a good matching between the engine output torque and the pump input torque during excavation work or the like. In this case, in a specific work that increases the load on the engine, for example, heavy excavation work, the pump tilt angle must be reduced to prevent engine stall. Along with this, the pump discharge flow rate decreases, the operating speed of the actuator related to heavy excavation work becomes slow, and the workability tends to deteriorate in heavy excavation work.

  The present invention has been made from the actual situation in the above-described prior art. The purpose of the present invention is to maintain the matching between the engine output torque and the pump input torque, while maintaining the matching between the engine output torque and the pump input torque. An object of the present invention is to provide an output control device for a work machine that can increase the size of the working machine.

  In order to achieve the above object, the present invention provides an engine provided with a turbocharger, a variable displacement hydraulic pump driven by the engine, and a regulator for controlling a tilt angle of the variable displacement hydraulic pump. An output control device for a work machine comprising: a hydraulic actuator driven by pressure oil discharged from the variable displacement hydraulic pump; and pump input torque control means for controlling input torque of the variable displacement hydraulic pump. The specific work detecting means for detecting that the load applied to the engine is large, and when the specific work detecting means detects that the specific work is detected, the supercharging pressure is compared with that before. The supercharging pressure control means for controlling to be high, and the pump input according to the supercharging pressure controlled to be high by the supercharging pressure control means It is characterized in that a pump input torque change means for changing to be larger the pump input torque being controlled by torque control means.

  In the present invention configured as described above, the pump input torque control means can bring the pump input torque close to the engine output torque within a range in which engine stall does not occur, and the matching between the engine output torque and the pump input torque can be realized.

  In particular, when it is detected by the specific work detection means that the load is applied to the engine such as heavy excavation work in a hydraulic excavator, for example, the supercharging pressure is controlled by the supercharging pressure control means. The pump input torque changing means changes the pump input torque so as to be larger than before according to the increased supercharging pressure. Here, the boost pressure and the intake air amount of the engine are in a proportional relationship, and the intake air amount and the fuel injection amount are in a proportional relationship. Further, when the fuel injection amount increases, the engine output torque increases. That is, in the present invention, the engine output torque can be increased more than before by increasing the supercharging pressure during specific work. Along with this, the pump input torque can be greatly changed within a range in which engine stall does not occur, and thereby the discharge flow rate of the variable displacement hydraulic pump can be increased.

  Further, the present invention is characterized in that, in the above invention, the supercharging pressure control means includes a supercharging pressure control valve capable of controlling the flow of exhaust gas in the exhaust pipe of the engine.

  In the present invention configured as described above, when the specific work detecting means detects a specific work that increases the load on the engine, the supercharging pressure control valve controls the exhaust flow in the exhaust pipe of the engine. To be implemented. As a result, the supercharging pressure can be increased.

  Further, the present invention is the above invention, further comprising a muffler that discharges exhaust discharged from an exhaust turbine of the turbocharger, wherein the supercharging pressure control means branches from the exhaust pipe of the engine, and the muffler And the supercharging pressure control valve is provided in the branch line.

  In the present invention configured as described above, when a specific work that increases the load on the engine is detected by the specific work detecting means, a branch pipe connected to the muffler from the exhaust pipe by, for example, a supercharging pressure control valve is provided. Closed. As a result, exhaust emission from the muffler can be suppressed, and the boost pressure can be increased.

  Further, the present invention is the above invention, wherein the pump input torque changing means includes an intake air amount detector for detecting an intake air amount in the intake pipe of the engine, and a controller to which the intake air amount detector is connected. The controller includes an input unit to which the intake air amount detected by the intake air amount detector is input, a relationship between the intake air amount and the fuel injection amount, and the fuel injection amount and the variable displacement hydraulic pump. And a fuel injection unit based on the relationship between the intake angle detected by the intake air amount detector and the relationship between the intake air amount and the fuel injection amount stored in the storage unit. An arithmetic processing unit that calculates an amount and calculates a target tilt angle based on the calculated fuel injection amount and the relationship between the fuel injection amount and the tilt angle stored in the storage unit; Eyes calculated by the department A control signal corresponding to the tilting angle is characterized by an output unit for outputting to the regulator.

  In the present invention configured as described above, when the supercharging pressure is increased by the control of the supercharging pressure control valve as described above and the engine output torque is increased, the intake air amount at that time is the intake air amount detector. When detected, the arithmetic processing unit of the controller obtains the fuel injection amount from the relationship between the intake air amount and the fuel injection amount, and the obtained fuel injection amount and the previously stored fuel injection amount-tilt angle. From this relationship, the target tilt angle is obtained. This target tilt angle is larger than the tilt angle before the boost pressure is increased, and the regulator is controlled to increase the tilt angle of the variable displacement hydraulic pump by this target tilt angle. To do.

  Further, the present invention is the above invention, wherein the specific work detection means includes a pressure detector that detects a pressure related to a load of the hydraulic actuator, and the supercharging pressure control means is connected to the pressure detector. A controller including an input unit to which the detected pressure detected by the pressure detector is input; a storage unit for storing a relationship between the detected pressure and the boost pressure control valve opening; and the pressure An arithmetic processing unit that calculates a target boost pressure control valve opening based on the detected pressure detected by the detector and the relationship between the detected pressure stored in the storage unit and the boost pressure control valve opening And an output section for outputting a control signal corresponding to the target boost pressure control valve opening calculated by the calculation processing section to the drive section of the boost pressure control valve.

  In the present invention configured as described above, when the pressure detector detects that the pressure corresponds to the specific work, the controller calculates the target excess from the relationship between the detected pressure and the boost pressure control valve opening degree. A supply pressure control valve opening is required. The target boost pressure control valve opening at this time is an opening that suppresses the flow of exhaust in the exhaust pipe of the engine. As a result, the supercharging pressure can be increased.

  In the present invention, while maintaining the matching between the engine output torque and the pump input torque by the pump input torque control means, the boost pressure is increased by the boost pressure control means at the time of specific work in which the load on the engine is increased, The engine output torque can be made larger than before. Accordingly, the pump input torque is made larger than that in the state where the matching with the engine output torque has been maintained as described above within a range in which the engine stall is not caused by the pump input torque changing means. be able to. As a result, the discharge flow rate of the variable displacement hydraulic pump can be increased, the decrease in the operating speed of the actuator during a specific operation can be suppressed, and the workability of the specific operation that increases the load on the engine has been conventionally achieved. It can be improved as compared.

  The best mode for carrying out an output control device for a work machine according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a circuit diagram showing an embodiment of an output control device for a work machine according to the present invention, and FIG. 2 is a block diagram showing a configuration of a controller provided in this embodiment. 3 to 6 are diagrams showing the correlation stored in the storage unit of the controller provided in this embodiment, FIG. 3 is a PQ diagram showing the relationship between the pump discharge pressure and the pump discharge flow rate, and FIG. 4 is the pressure FIG. 5 shows the relationship between the detected pressure of the detector and the boost pressure control valve opening, FIG. 5 shows the relationship between the intake air amount and the fuel injection amount, and FIG. 6 shows the fuel injection amount and the variable displacement hydraulic pump. It is a figure which shows the relationship with a tilt angle.

  The present embodiment is provided in a work machine such as a hydraulic excavator, and this hydraulic excavator is provided with a turbo-type supercharger 4 including a centrifugal compressor 4a and an exhaust turbine 4b as shown in FIG. An engine 1 and a fuel injection pump 2 that supplies fuel to the engine 1 through a supply line 3 are provided.

  In addition, the turbocharger 4 is connected to a centrifugal compressor 4a, and an intake pipe 5 for supplying the sucked outside air to the engine 1; exhaust gas discharged from the engine 1 is used as an exhaust turbine of the turbocharger 4 And an exhaust pipe 6 leading to 4b. An intake air line 5 is provided with an intercooler 8 for cooling the compressed air and a throttle valve 9 for adjusting the amount of air sent to the engine 1. Further, a muffler 10 for releasing the exhaust to the outside is provided downstream of the exhaust turbine 4b.

  The hydraulic excavator includes a variable displacement hydraulic pump 11 driven by the engine 1, a regulator 12 that controls the tilt angle of the hydraulic pump 11, and a boom cylinder to which pressure oil discharged from the hydraulic pump 11 is supplied. And hydraulic actuators 13 and 14 such as arm cylinders, and a controller 19 that outputs a control signal to the regulator 19.

  The output control device according to the present embodiment provided in such a hydraulic excavator detects the discharge pressure of the hydraulic pump 11 and outputs a detection signal to the controller 19, and the tilt angle of the hydraulic pump 11. And a tilt angle detector 16 that outputs a detection signal to the controller 19.

  In particular, pressure detectors 17 and 18 that detect pressures related to loads of the hydraulic actuators 13 and 14, for example, relief pressures of the hydraulic actuators 13 and 14, and output detection signals to the controller 19 are provided.

  In addition, an intake air amount detector 20 is provided between the intercooler 8 and the throttle valve 9 of the intake pipe 5 for detecting the amount of intake air sucked by the intake pipe 5 and outputting a detection signal to the controller 19. .

  In addition, a branch line 21 that branches from the exhaust pipe 6 of the engine 1 and is connected to the muffler 10 is provided, and the flow of exhaust gas in the exhaust pipe 6 of the engine 1 can be suppressed in the branch line 21. For example, a supercharging pressure control valve 22 capable of opening and closing the branch pipe 21 is disposed.

  As shown in FIG. 2, the controller 19 includes an input unit 19a, an arithmetic processing unit 19b, a storage unit 19c, and an output unit 19d.

  The input portion 19a of the controller 19 includes a discharge pressure detected by the discharge pressure detector 15 described above, a tilt angle detected by the tilt angle detector 16, a detected pressure detected by the pressure detectors 17 and 18, A detection signal relating to each of the intake air amounts detected by the intake air amount detector 20 is input.

  In the storage unit 19c of the controller 19, as shown in FIG. 3, a pump discharge pressure P and a pump discharge flow rate that give a pump input torque having a torque value substantially equal to the engine output torque within a range where the engine 1 does not stall. A PQ diagram which is a relationship of Q is stored. Further, as shown in FIG. 4, the opening degree of the supercharging pressure control valve 22 is fully opened until the detected pressure of the pressure detectors 17, 18, for example, the pressure detector 17 reaches the relief pressure Pr of the hydraulic actuator 13, The relationship between the detected pressure that is fully closed above the relief pressure Pr and the boost pressure control valve opening is stored. Although not shown, the relationship between the detected pressure of the pressure detector 18 and the boost pressure control valve opening is the same, and this is also stored in the storage unit 19c. Further, as shown in FIG. 5, the relationship between the intake air amount and the fuel injection amount, which is a relationship in which the fuel injection amount increases in proportion to the increase in the intake air amount, is stored. Further, as shown in FIG. 6, the fuel injection amount and the tilt angle, in which the tilt angle increases in proportion to the increase in the fuel injection amount between the minimum tilt angle and the maximum tilt angle. The relationship is stored.

  The arithmetic processing unit 19b of the controller 19 calculates the pump input torque based on the discharge pressure and the tilt angle detected by the discharge pressure detector 15 and the tilt angle detector 16, respectively, and in a range that does not cause an engine stall. A calculation is performed to obtain a target tilt angle that gives a pump input torque having a torque value substantially equal to the engine output torque. Further, as described above, for example, based on the detected pressure detected by the pressure detector 17 and the relationship between the detected pressure and the boost pressure control valve opening stored in the storage unit 19c as shown in FIG. A calculation for obtaining the target boost pressure control valve opening is performed. Further, calculation for determining the fuel injection amount based on the intake air amount detected by the intake air amount detector 20 and the relationship between the intake air amount and the fuel injection amount stored in the storage unit 19c as shown in FIG. Based on the obtained fuel injection amount and the relationship between the fuel injection amount and the tilt angle stored in the storage unit 19c as shown in FIG. 6, a calculation for obtaining the target tilt angle is performed.

  Further, from the output unit 19d of the controller 19, for example, a control signal corresponding to the target tilt angle obtained by the arithmetic processing unit 19c is output to the regulator 12. Further, a control signal corresponding to the boost pressure control valve opening obtained by the arithmetic processing unit 19 c is output to the drive unit of the boost pressure control valve 22.

  The engine stall is determined based on the discharge pressure detector 15, the tilt angle detector 16, the discharge pressure detected by the discharge pressure detector 15, and the tilt angle detected by the tilt angle detector. The controller 19 including an arithmetic processing unit 19c that performs an operation for obtaining a pump input torque matched with the engine output torque within a range that does not occur constitutes pump input torque control means for controlling the input torque of the variable displacement hydraulic pump 11. is doing.

  Further, the pressure detectors 17 and 18 that detect the relief pressure Pr of the hydraulic actuators 13 and 14 and output them to the controller 19 detect that the work is a specific work that increases the load on the engine 1, for example, a heavy excavation work. The specific work detecting means is configured.

  Further, the above-described supercharging pressure control valve 21, the branch pipe 21 in which the supercharging pressure control valve 21 is disposed, a storage unit 19c that stores the relationship between the detected pressure and the supercharging pressure control valve opening degree, and The controller 19 including the calculation processing unit 19b for calculating the target supercharging pressure control valve opening degree is supercharged when the above-mentioned specific work detecting means detects that the work is a specific work, for example, a heavy excavation work. A supercharging pressure control means for controlling the pressure to be higher than before is configured.

  Further, the fuel injection amount is obtained based on the intake air amount detector 20 described above, the intake air amount detected by the intake air amount detector 20, and the relationship shown in FIG. The supercharging pressure controlled to be increased by the supercharging pressure control means described above by the controller 19 including the arithmetic processing unit 19b that performs an operation for obtaining the target tilt angle based on the amount and the relationship shown in FIG. Correspondingly, pump input torque changing means for changing the pump input torque so far controlled by the pump input torque control means so as to increase is configured.

  In the present embodiment configured as described above, for example, a relatively light excavation work in which the load on the engine 1 is not so large and the load on the hydraulic actuators 13 and 14 does not reach the relief pressure Pr shown in FIG. 4 is calculated from the relationship shown in FIG. 4 by the arithmetic processing unit 19b of the controller 19 that the supercharging pressure control valve opening is fully open, and a control signal corresponding to this full opening is sent to the supercharging pressure control valve 22. Is output. As a result, the branch pipe 21 is opened, and the exhaust gas discharged from the engine 1 is guided to the muffler 10 via the exhaust pipe 6 and the exhaust turbine 4b of the turbocharger 4, and from the muffler 10 to the outside. Released. That is, since the engine 1 is exhausted smoothly, the supercharging pressure is relatively low.

  FIG. 7 is a diagram showing the relationship between the supercharging pressure control valve opening degree and the supercharging pressure obtained in this embodiment, and FIG. 8 is a diagram showing the relationship between the supercharging pressure and the intake air amount obtained in this embodiment. is there. As shown in FIG. 7, when the supercharging pressure is low, the supercharging pressure control valve opening is kept open as described above. At this time, as shown in FIG. The amount is relatively small depending on the supply pressure. In such a state, a PQ diagram corresponding to the discharge pressure detected by the discharge pressure detector 15 and the tilt angle detected by the tilt angle detector 16, that is, the characteristic line of FIG. The pump input torque is controlled by A. While such an operation is performed, matching with the engine output torque is maintained.

  Further, for example, when a specific work in which a load on the engine 1 is increased, for example, a heavy excavation work, the pressure detector 17 detects the relief pressure Pr. At this time, from the relationship stored in the storage unit 19c shown in FIG. 4, the calculation processing unit 19b of the controller 19 determines that the boost pressure control valve opening is fully closed. A control signal corresponding to this full closing is output from the output unit 19d to the drive unit of the supercharging pressure control valve 22, the supercharging pressure control valve 22 is closed, and the branch line 21 is closed. Thereby, the flow of the exhaust pipe 6 is suppressed, and the supercharging pressure is increased. Thus, when the supercharging pressure increases, the intake air amount increases as is apparent from the relationship shown in FIG. Therefore, the intake air amount detected by the intake air amount detector 20 becomes larger than before, and the fuel injection amount obtained by the arithmetic processing unit 19b is calculated from the relationship of FIG. 5 stored in the storage unit 19c of the controller 19. growing.

  As a phenomenon during this time, when the intake air amount increases as described above, the fuel injection amount of the engine 1 increases and the output torque of the engine 1 increases. That is, it is possible to change the pump input torque to be larger than the pump input torque so far, so that the torque value becomes almost equal to the increased engine output torque within a range where no engine stall occurs.

  In the arithmetic processing unit 19b of the controller 19 described above, following the calculation for obtaining the fuel injection amount, the relationship shown in FIG. 6 stored in the storage unit 19c corresponds to the increased fuel injection amount, which is larger than before. The tilt angle is obtained as the target tilt angle. A control signal corresponding to the target tilt angle is output from the output unit 19d to the regulator 12. Accordingly, the PQ diagram shown in FIG. 3 can be changed from the characteristic line A to the characteristic line B, and the matching between the engine output torque and the pump input torque is maintained by the characteristic line B. As described above, by making the tilt angle larger than before, the pump discharge flow rate is increased, and the decrease in the operating speed of the hydraulic actuators 13 and 14 is suppressed.

  According to the present embodiment configured as described above, the load applied to the engine 1 becomes large while the matching between the engine output torque and the pump input torque is maintained by the pump input torque control means, and the pressure detector 17 During heavy excavation work in which the relief pressure Pr of the actuator 13 is detected, the boost pressure can be increased by the boost pressure control means including the boost pressure control valve 22 to increase the output torque of the engine 1 than before. it can. Along with this, the tilt angle of the hydraulic pump 11 is increased by the pump input torque changing means described above, and the pump input torque can be made larger than before without causing engine stall. The discharge amount can be increased. Thereby, the fall of the operating speed of the hydraulic actuators 13 and 14 at the time of heavy excavation work can be suppressed, and workability in such heavy excavation work that increases the load on the engine 1 can be improved.

  In the above embodiment, pressure detectors 17 and 18 for detecting the relief pressure of the hydraulic actuators 13 and 14 are provided as specific work detection means for detecting a specific work such as heavy excavation work in which the load on the engine 1 increases. However, the present invention is not limited to such a configuration, and the specific work detection means may be configured by the discharge pressure detector 15 that detects the discharge pressure of the hydraulic pump 11. Good.

It is a circuit diagram showing one embodiment of an output control device of a work machine concerning the present invention. It is a block diagram which shows the structure of the controller with which this embodiment is equipped. It is a PQ diagram which shows the relationship between the pump discharge pressure memorize | stored in the memory | storage part of the controller with which this embodiment is provided, and pump discharge flow volume. It is a figure which shows the relationship between the detection pressure of the pressure detector memorize | stored in the memory | storage part of the controller with which this embodiment is provided, and a supercharging pressure control valve opening degree. It is a figure which shows the relationship between the intake air quantity memorize | stored in the memory | storage part of the controller with which this embodiment is provided, and fuel injection quantity. It is a figure which shows the relationship between the fuel injection quantity memorize | stored in the memory | storage part of the controller with which this embodiment is provided, and the tilt angle of a variable displacement hydraulic pump. It is a figure which shows the relationship between the supercharging pressure control valve opening degree and supercharging pressure which are obtained in this embodiment. It is a figure which shows the relationship between the supercharging pressure obtained by this embodiment, and the amount of intake air.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 4 Turbo-type supercharger 4a Centrifugal compressor 4b Exhaust turbine 5 Intake pipe 6 Exhaust pipe 10 Muffler 11 Variable capacity hydraulic pump 12 Regulator 13 Hydraulic actuator 14 Hydraulic actuator 15 Discharge pressure detector (pump input torque control) means)
16 Tilt angle detector (pump input torque control means)
17 Pressure detector (specific work detection means)
18 Pressure detector (specific work detection means)
19 Controller (pump input torque control means) (supercharging pressure control means) (pump input torque change means)
19a input unit 19b arithmetic processing unit 19c storage unit 19d output unit 20 intake air amount detector (pump input torque changing means)
21 Branch line (supercharging pressure control means)
22 Supercharging pressure control valve (Supercharging pressure control means)

Claims (5)

An engine equipped with a turbocharger, a variable displacement hydraulic pump driven by the engine, a regulator that controls the tilt angle of the variable displacement hydraulic pump, and the variable displacement hydraulic pump that discharges In an output control device for a work machine comprising a hydraulic actuator driven by pressure oil and pump input torque control means for controlling input torque of the variable displacement hydraulic pump,
A specific work detecting means for detecting that the load on the engine is a specific work;
A supercharging pressure control means for controlling the supercharging pressure to be higher than before when the specific work detecting means detects that the specific work is performed;
And a pump input torque changing means for changing the pump input torque controlled by the pump input torque control means so as to increase in accordance with the boost pressure controlled to be higher by the supercharging pressure control means. An output control device for a work machine. In the invention of claim 1,
The output control device for a work machine, wherein the supercharging pressure control means includes a supercharging pressure control valve capable of controlling an exhaust flow of an exhaust pipe of the engine. In the invention of claim 2,
A muffler that discharges exhaust discharged from an exhaust turbine of the turbocharger,
The supercharging pressure control means includes a branch pipe branched from the exhaust pipe of the engine and connected to the muffler, and the supercharging pressure control valve is provided in the branch pipe. Output control device for work machines. In the invention of claim 2,
The pump input torque changing means includes an intake air amount detector for detecting an intake air amount of the intake pipe of the engine, and a controller to which the intake air amount detector is connected,
The controller includes an input unit to which the intake air amount detected by the intake air amount detector is input, a relationship between the intake air amount and the fuel injection amount in advance, and the inclination of the fuel injection amount and the variable displacement hydraulic pump. The fuel injection amount is determined based on the storage unit that stores the relationship with the turning angle, the intake air amount detected by the intake air amount detector, and the relationship between the intake air amount and the fuel injection amount stored in the storage unit. An arithmetic processing unit that performs an operation for calculating a target tilt angle based on the calculated fuel injection amount and the relationship between the fuel injection amount and the tilt angle stored in the storage unit, and the arithmetic processing unit An output control device for a work machine, comprising: an output unit that outputs a control signal corresponding to the calculated target tilt angle to the regulator. In the invention of claim 2,
The specific work detection means includes a pressure detector that detects a pressure related to a load of the hydraulic actuator,
The supercharging pressure control means includes a controller to which the pressure detector is connected;
This controller has an input unit to which the detected pressure detected by the pressure detector is input, a storage unit for storing the relationship between the detected pressure and the boost pressure control valve opening in advance, and the pressure detector. An arithmetic processing unit for calculating a target boost pressure control valve opening based on the detected pressure and the relationship between the detected pressure stored in the storage unit and the boost pressure control valve opening; and An output control device for a work machine, comprising: an output unit that outputs a control signal corresponding to the target boost pressure control valve opening calculated by the processing unit to the drive unit of the boost pressure control valve.

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