JP4425600B2 - Construction machine control equipment - Google Patents

Description

  The present invention relates to a construction machine control device that controls input torque acting on a prime mover of a construction machine.

  A traveling hydraulic motor driven by oil discharged from a variable displacement hydraulic pump driven by an engine, for example, controls the amount of pressure oil guided to the hydraulic motor according to the operation of the traveling pedal, and travels the vehicle. A construction machine is known in which the engine speed can be controlled in accordance with the operation of a travel pedal (see, for example, Patent Document 1).

  In the construction machine described in the patent document, input torque control is performed by speed sensing as follows. That is, a target torque for preventing engine stall is calculated from the deviation between the actual engine speed detected by the speed sensor and the target speed corresponding to the governor lever position of the engine, and the target pump tilt is calculated from this target torque. The tilt angle is obtained to control the pump tilt angle. In calculating the target torque, only control in the direction in which the input torque increases is performed, and control in the direction in which the input torque decreases is not performed. As a result, the tilt angle of the hydraulic pump is maintained at a predetermined value or more, and smooth acceleration can be ensured.

Japanese Patent No. 2633095

  By the way, in recent years, an exhaust gas-compatible engine is used in order to suppress the generation of black smoke. The engine corresponding to exhaust gas is one in which the engine output torque on the low rotation side in the full load performance curve of the engine is smaller than that of the conventional one. More specifically, the maximum output torque of the engine is shifted to the high rotation side, the torque rise from the low rotation range to the middle rotation range is reduced, and the torque rise from the middle rotation range to the high rotation range is increased. As a result, fuel consumption on the low rotation side is suppressed, and generation of black smoke is suppressed.

  When the input torque control described in the above publication is performed when such an exhaust gas-compatible engine is used, the following problem occurs. That is, since the construction machine described in the above publication does not perform control to reduce the input torque, when the running load increases in a region where the engine output torque is small, such as when starting running or running uphill, the input torque is output to the engine output. Exceeding torque may cause engine stall.

A construction machine control device according to the present invention has a function of changing an input torque acting on a prime mover, a variable displacement hydraulic pump driven by the prime mover, a rotational speed setting means for setting a target rotational speed of the prime mover, and a rotational speed Rotational speed control means for controlling the rotational speed of the prime mover according to the target rotational speed set by the setting means, and the target rotational speed so that the input torque acting on the prime mover changes with a delay relative to the change in the target rotational speed and an input torque control means for controlling the input torque in accordance with the arithmetic and rotational speed delay section for outputting delayed a target rotational speed for the torque control, the target input torque corresponding to the target speed which is the delay The input torque control means is configured by a torque calculating unit that controls the input torque of the hydraulic pump to the target input torque calculated by the torque calculating unit.
The rotational speed delay unit preferably outputs the target rotational speed for torque control with a primary delay.

  According to the present invention, the input torque is controlled in accordance with the target rotational speed so that the input torque acting on the prime mover is delayed with respect to the change in the target rotational speed of the prime mover. Even when is used, the input torque at the start of traveling can be made smaller than the output torque of the prime mover, and engine stall can be prevented.

Hereinafter, an embodiment in which a construction machine control device according to the present invention is applied to a wheeled hydraulic excavator will be described with reference to FIGS.
As shown in FIG. 1, the wheeled hydraulic excavator includes a traveling body 1 and a revolving body 2 that is turnably mounted on an upper portion of the traveling body 1. The swivel body 2 is provided with a work front attachment 4 including a cab 3, a boom 4 a, an arm 4 b, and a bucket 4 c. The boom 4a is raised and lowered by driving the boom cylinder 4d, the arm 4b is raised and lowered by driving the arm cylinder 4e, and the bucket 4c is clouded or dumped by driving the bucket cylinder 4f. The traveling body 1 is provided with a traveling hydraulic motor 5 that is hydraulically driven. The rotation of the traveling motor 5 is transmitted to wheels 6 (tires) through a propeller shaft and an axle.

  FIG. 2 shows a hydraulic circuit for traveling and working. The variable displacement hydraulic pump 10 is connected to the hydraulic motor 5 via a control valve 11 and is connected to a hydraulic cylinder (for example, a boom cylinder 4d) via a control valve 12. The pilot port of the control valve 11 is connected to the pilot valve 14 via the forward / reverse switching valve 13, and the pilot port of the control valve 12 is connected to the pilot valve 15.

  The forward / reverse switching valve 13 is switched by a switch (not shown), and the pilot valve 14 is driven according to the operation amount of the travel pedal 14a. When the forward / reverse switching valve 13 is switched to the forward position or the reverse position by operating the switch and the travel pedal 14a is operated, the pilot pressure from the hydraulic pressure source 16 acts on the control valve 11. As a result, the control valve 11 is driven and the pressure oil from the hydraulic pump 10 is supplied to the hydraulic motor 5, and the vehicle can be moved forward or backward by the rotation of the hydraulic motor 5.

  On the other hand, the pilot valve 15 is driven according to the operation amount of the operation lever 15a. When the operation lever 15 a is operated, the pilot pressure from the hydraulic pressure source 17 acts on the control valve 12. As a result, the control valve 12 is driven and pressure oil from the hydraulic pump 10 is supplied to the boom cylinder 4d, and excavation work or the like can be performed by driving the boom cylinder 4d.

  The hydraulic pump 10 is driven by the engine 20, and the pump tilt angle qp is changed by the regulator 30. Pump discharge pressure is fed back to the regulator 30, and horsepower control is performed. The horsepower control is so-called P-qp control as shown in FIG. At the same time, in the present embodiment, as described later, speed sensing is performed to calculate the input torque, and the pump tilt angle pq is controlled in accordance with this input torque. As a result, the input torque is increased or decreased as indicated by the arrows in FIG.

  In the present embodiment, an exhaust gas compatible engine is used to suppress the generation of black smoke. FIG. 4 is a characteristic diagram showing a full load performance curve of the engine. The engine characteristic corresponding to exhaust gas is indicated by a solid line, and the engine characteristic not corresponding to exhaust gas is indicated by a dotted line. As shown in FIG. 4, the engine corresponding to exhaust gas is one in which the output torque T on the low rotation side is reduced. More specifically, the maximum output torque is shifted to the high rotation side, the torque rise from the low rotation region to the middle rotation region is reduced, and the torque rise from the middle rotation region to the high rotation region is increased. By using an engine with such characteristics, fuel consumption on the low rotation side is suppressed, and the generation of black smoke is suppressed.

  FIG. 5 is a block diagram of the control device according to the present embodiment. The governor lever 21 of the engine 20 is connected to the pulse motor 23 via the link mechanism 22, and the engine speed is controlled by the rotation of the pulse motor 23. That is, the engine speed increases with the forward rotation of the pulse motor 23 and decreases with the reverse rotation. The rotation of the pulse motor 23 is controlled by a control signal from the controller 40 as described later. A potentiometer 24 is connected to the governor lever 21 via a link mechanism 22, and the governor lever angle corresponding to the rotational speed of the engine 20 is detected by the potentiometer 24 and input to the controller 40 as the engine control rotational speed Nθ.

  Further, the controller 40 includes a rotation speed sensor 31 for detecting the actual rotation speed Nr of the engine 20, a brake switch 32, a position sensor 33 for detecting the switching position of the forward / reverse switching valve 13, and an operation for engine speed command. A detector 35 that detects the operation amount X of the fuel lever 34, which is a member, and a pressure sensor 36 that detects a pilot pressure Pt corresponding to the operation amount of the travel pedal 14a are connected.

  The brake switch 32 is switched to running, working and parking positions and outputs a working / running signal. When switched to the running position, the parking brake is released and the service brake is allowed to operate by the brake pedal. When switched to the working position, the parking brake and service brake are activated. When switched to the parking position, the parking brake is activated. When switched to the travel position, the brake switch 32 outputs an ON signal, and when switched to the work and parking position, it outputs an OFF signal.

  The controller 40 includes a torque control unit 40A that controls input torque and a rotation speed control unit 40B that controls engine rotation speed. FIG. 6 is a conceptual diagram illustrating details of the torque control unit 40A.

  The torque control unit 40A includes a deviation calculation unit 41 that calculates a deviation ΔN between the engine actual rotation speed Nr and the control rotation speed Nθ, reference torque calculation units 42 and 43 that calculate reference torques TB1 and TB2, respectively, and a control rotation speed Nθ. First-order lag filter 55 that outputs a first-order lag and outputs it as control rotational speed Nθ1, correction torque calculation units 44 and 45 that respectively calculate correction torques ΔT1 and ΔT2, coefficient calculation units 46 and 47 that respectively calculate coefficients, and correction Multipliers 48 and 49 for multiplying torques ΔT1 and ΔT2 and coefficients, respectively, and adders 50 and 51 for calculating target input torques T1 and T2 by adding the corrected torques ΔT1 and ΔT2 after multiplication and the reference torques TB1 and TB2, respectively. In order to control the pump input torque to the selected target input torque T1 or T2, the selection unit 52 that selects one of the target input torques T1 and T2 And a converter 53 for outputting a control signal i.

  The reference torque calculation unit 42, the correction torque calculation unit 44, and the coefficient calculation unit 46 are each set with characteristics suitable for work, and the reference torque calculation unit 43, the correction torque calculation unit 45, and the coefficient calculation unit 47 are suitable for running, respectively. Characteristics are set.

The calculation in the torque control unit 40A will be described in detail.
The first-order lag filter 55 delays the control rotational speed Nθ (dotted line) detected by the potentiometer 24 as shown in FIG. As shown in FIG. 6, the relationship between the control rotational speeds Nθ and Nθ1 and the reference torques TB1 and TB2 is stored in advance in the respective reference torque calculation units 42 and 43.

  The characteristics of the reference torque calculators 42 and 43 are set based on the output torque characteristics of the engine 20, and the reference torques TB1 and TB2 are small in a region where the control rotational speeds Nθ and Nθ1 are low, and then the control rotational speeds Nθ and Nθ1 increase. Accordingly, the reference torques TB1 and TB2 are increased, and are set along the full load performance of the engine and not to exceed the full load performance. Based on such characteristics stored in the reference torque calculators 42 and 43, the reference torque calculator 42 calculates the reference torque TB 1 corresponding to the control rotational speed Nθ detected by the potentiometer 24, and the reference torque calculator 43 Calculates a reference torque TB2 corresponding to the control rotational speed Nθ1 output from the primary delay filter 55.

  The deviation calculator 41 calculates a deviation ΔN (= Nr−Nθ) between the actual engine speed Nr detected by the engine speed sensor 31 and the control engine speed Nθ detected by the potentiometer 24. This deviation ΔN is input to the correction torque calculators 44 and 45, respectively. As shown in the figure, the relationship between the deviation ΔN and the correction torques ΔT1 and ΔT2 is stored in advance in the correction torque calculation units 44 and 45, and the correction torques ΔT1 and ΔT2 corresponding to the deviation ΔN are calculated from these characteristics.

  According to the characteristics of the correction torque calculator 44, the correction torque ΔT1 is positive when the deviation ΔN is positive, and the correction torque ΔT1 increases proportionally as the deviation ΔN increases. When the deviation ΔN is negative, the correction torque ΔT1 is also negative. As the deviation ΔN decreases, the correction torque ΔT1 decreases proportionally (| ΔT1 | increases). In this case, the slope of the characteristic when the deviation ΔN is positive is equal to the slope of the characteristic when the deviation ΔN is negative.

  On the other hand, according to the characteristics of the correction torque calculator 45, when the deviation ΔN is positive, the correction torque ΔT2 is also positive, and the correction torque ΔT increases proportionally as the deviation ΔN increases. On the other hand, when the deviation ΔN is negative, the correction torque ΔT2 is zero. Therefore, torque correction is not performed when the deviation ΔN is negative.

  Each coefficient calculating section 46, 47 stores in advance a characteristic that the coefficient increases in proportion to the control rotation speed Nθ as shown in the figure, and calculates a coefficient corresponding to the control rotation speed Nθ from this characteristic. Each multiplying unit 48, 49 multiplies the correction torques ΔT1, ΔT2 calculated by the correction torque calculating units 44, 45 by the coefficients calculated by the coefficient calculating units 46, 47.

  The addition units 50 and 51 add the correction torque ΔT multiplied by the multiplication units 48 and 49 and the reference torques TB1 and TB2 calculated by the reference torque calculation units 42 and 43, respectively, and calculate the target input torques T1 and T2. To do.

  The selection unit 52 determines whether or not the vehicle is traveling based on signals from the brake switch 32, the position sensor 33, and the pressure sensor 36. That is, when the brake switch 32 is turned off, the forward / reverse switching valve 13 is in a position other than the neutral position, and the pilot pressure Pt by the operation of the travel pedal 14a is equal to or greater than a predetermined value, it is determined that the vehicle travels. Then, it is determined that the vehicle is not running. Then, the target input torque T2 is selected when the vehicle is traveling, and the target input torque T1 is selected when the vehicle is not traveling (for example, during work).

  The conversion unit 53 calculates a control signal i corresponding to the selected target input torque T1 or T2. Although not shown, the pump regulator 30 is provided with a tilt angle adjusting cylinder and a solenoid valve for controlling the flow of pressure oil to the cylinder, and a control signal i from the converter 53 is output to the solenoid valve. Is done. As a result, the pump tilt angle qp is changed, and the input torque is controlled to the target input torque T1 or T2.

  FIG. 8 is a conceptual diagram illustrating details of the rotation speed control unit 40B. As shown in the figure, the target rotational speed calculation unit 61 stores in advance the relationship between the detection value X detected by the detector 35 and the target rotational speed Nx. From this characteristic, the target rotational speed Nx corresponding to the operation amount of the fuel lever 34 is stored. Is calculated. As shown in the figure, the target rotational speed calculation unit 62 stores the relationship between the detected value Pt detected by the pressure sensor and the target rotational speed Nt in advance. From this characteristic, the target rotational speed Nt corresponding to the operation amount of the travel pedal 14a is obtained. Calculate.

  In this case, the target rotational speeds Nx and Nt linearly increase from the idle rotational speed Ni as the operation amount increases in the characteristics of the target rotational speed calculators 61 and 62. The maximum target rotational speed Nxmax of the target rotational speed calculation unit 61 is set lower than the maximum rotational speed of the engine 20, and the maximum target rotational speed Ntmax of the target rotational speed calculation unit 62 is set substantially equal to the maximum rotational speed of the engine 20. Yes. Therefore, the maximum target speed Ntmax is larger than the maximum target speed Nxmax.

  The selection unit 63 selects the larger value of the target rotation speeds Nx and Nt calculated by the target rotation speed calculation units 61 and 62. The servo control unit 64 compares the selected rotational speed (rotational speed command value Nin) with the control rotational speed Nθ corresponding to the displacement amount of the governor lever 21 detected by the potentiometer 24. Then, according to the procedure shown in FIG. 9, the pulse motor 23 is controlled so that they coincide.

  In FIG. 9, first, at step S21, the rotational speed command value Nin and the control rotational speed Nθ are read, and the process proceeds to step S22. In step S22, the result of Nθ−Nin is stored in the memory as a rotational speed difference A, and in step S23, it is determined whether | A | ≧ K using a predetermined reference rotational speed difference K. If the determination is affirmative, the routine proceeds to step S24, where it is determined whether the rotational speed difference A> 0 or not. Therefore, in order to reduce the engine speed, a signal for instructing motor reverse rotation is output to the pulse motor 23 in step S25. As a result, the pulse motor 23 reverses and the engine speed decreases.

  On the other hand, if A ≦ 0, the control rotational speed Nθ is smaller than the rotational speed command value Nin, that is, the control rotational speed is lower than the target rotational speed. Is output. As a result, the pulse motor 23 rotates forward and the engine speed increases. If step S23 is negative, the process proceeds to step S27 to output a motor stop signal, whereby the engine speed is held at a constant value. When steps S25 to S27 are executed, the process returns to the beginning.

Next, a characteristic operation of the control device according to the present embodiment will be described.
At the start of vehicle travel, the brake switch 32 is operated to the travel position, and the forward / reverse switching valve 13 is switched to the forward or reverse position. In this state, for example, when the fuel lever 34 is operated to the idle position and the travel pedal 14a is operated to maximize the driving force, the travel motor 5 is driven by the pressure oil from the hydraulic pump 10, and the vehicle is Start running. At this time, since the target rotational speed Nt by the travel pedal 14a is larger than the target rotational speed Nx by the fuel lever 34, the selection unit 63 selects the target rotational speed Nt as the rotational speed command value Nin and performs actual rotation according to the procedure of FIG. The governor lever position is controlled so that the number matches the rotation speed command value Nin. As a result, the governor lever 21 is greatly displaced, and the control rotational speed Nθ increases at a stroke as shown by the broken line in FIG.

  When the control rotation speed Nθ increases, the actual engine rotation speed Nr also increases. However, since there is a time lag until the actual engine rotation speed Nr reaches the control rotation speed Nθ, the actual engine rotation speed Nr increases gradually, and this time lag During this period, the deviation ΔN is negative. The engine output torque T in this case is as shown in FIG. 10B, and this characteristic is derived from the characteristic shown in FIG. Since the actual engine speed Nr rises gently, the engine output torque T also rises gently.

  When the vehicle travels, the selection unit 52 selects the target input torque T2, and the torque control unit 40A performs speed sensing based on the characteristics of the reference torque calculation unit 43 and the correction torque calculation unit 45. Immediately after the operation of the travel pedal 14a is started, the actual engine speed Nr is smaller than the control engine speed Nθ and the deviation | ΔN | is negative, so the correction torque ΔT2 of the correction torque calculator 45 becomes zero. Therefore, the reference torque TB2 calculated by the reference torque calculation unit 43 becomes the target input torque T2.

  In this case, the control rotational speed Nθ1 is delayed and input to the reference torque calculation unit 43 via the first-order lag filter 55 (FIG. 7). Therefore, the control rotation speed Nθ1 immediately after the start of the pedal operation is small, and the control rotation speed Nθ1 gradually increases with a delay from the control rotation speed Nθ. As a result, as shown in FIG. 10 (b), the reference torque TB2 also increases gently like the engine output torque T, and the input torque T2 at the start of traveling becomes smaller than the output torque T. As a result, engine stall at the start of traveling can be avoided. The first-order lag characteristic of the first-order lag filter 55 is determined in consideration of the engine lag time lag. The present embodiment operates in the same manner not only at the start of traveling but also when traveling uphill, where the load on the vehicle is large and an engine stall is likely to occur.

  A characteristic T20 in FIG. 10B is a characteristic when the reference torque TB2 is obtained as it is without first delaying the target rotational speed Nθ. According to this characteristic, the input torque T20 does not become smaller than the reference torque when the deviation ΔN is negative. Therefore, if an exhaust gas-compatible engine with a small output torque is used, the input torque T20 at the start of traveling may exceed the engine output torque T, which may cause engine stall.

  During work, the brake switch 32 is operated to the work position, and the forward / reverse switching valve 13 is switched to the neutral position. When the operation of the travel pedal 14a is stopped in this state and the fuel lever 34 is operated by a predetermined amount, the selection unit 63 of the rotation speed control unit 40B selects the target rotation speed Nx by the fuel lever 34 as the rotation speed command value Nin, and the actual rotation The governor lever position is controlled so that the number matches the rotation speed command value Nin. At this time, the selection unit 52 of the torque control unit 40A selects the target input torque T1, and the torque control unit 40A performs speed sensing based on the characteristics of the reference torque calculation unit 42 and the correction torque calculation unit 44. Since the correction torque ΔT is negative when the deviation ΔN of the correction torque calculation unit 44 is negative, the input torque T1 is always smaller than the output torque T as shown in FIG.

According to the present embodiment, the following effects can be achieved.
(1) The control rotation speed Nθ is delayed by the first order by the first-order lag filter 55 (Nθ1), the reference torque TB2 is calculated by the reference torque calculator 43 according to the control rotation speed Nθ1, and the input torque T2 is controlled to the reference torque TB2. I tried to do it. As a result, the reference torque TB2 rises gently at the start of travel, and even when an exhaust gas compatible engine is used, the input torque T2 at the start of travel can be made smaller than the output torque T, thereby preventing engine stall. be able to.

(2) When the deviation ΔN between the actual engine speed Nr and the control speed Nθ is negative, the torque correction by the correction torque calculator 45 is not performed (ΔT = 0), and the reference torque TB2 is delayed by the first order and the input torque T2 The rise was suppressed. Thereby, the input torque T2 can be sufficiently suppressed and hunting can be effectively suppressed. On the other hand, for example, when the deviation ΔN is negative, the characteristic of the correction torque calculator 45 is set so that the correction torque ΔT becomes a negative value, and the correction torque ΔT2 is subtracted from the reference torque TB2 to increase the input torque T2. In order to sufficiently suppress the input torque T2, it is necessary to make the inclination of the characteristic of the correction torque calculator 45 steep, and hunting is likely to occur.

(3) Since the reference torque TB2 is delayed by the first order, the characteristic of the input torque T2 corresponds well to the characteristic of the engine output torque T accompanying the time lag of the engine speed (FIG. 10 (b)) and prevents engine stall. However, good acceleration can be ensured.
(4) The characteristics for calculating the correction torque ΔT between running and non-running are changed, and the acceleration performance is not so much a problem when not running, so that the correction torque ΔT is also negative when the deviation ΔN is negative. As a result, the input torque T1 can always be kept below the output torque T during work.

  In the above embodiment, the control speed Nθ is delayed by the first order by the primary delay filter 55, and the reference torque TB2 is calculated according to the control speed Nθ1 after this primary delay. If the input torque T2 is controlled so that the input torque T2 changes with a delay with respect to the change, an input torque control means may be configured in addition to this.

  For example, a delay filter other than the first-order delay (second-order delay, third-order delay, etc.) may be provided as the rotation speed delay unit. Alternatively, a predetermined waiting time may be counted, and the control rotation speed Nθ may be output as the control rotation speed Nθ1 after the waiting time has elapsed. Although the control rotation speed Nθ is delayed and output by the first-order lag filter 55, the calculation value T2 of the input torque is delayed, but the calculation value T2 is not delayed but the regulator 30 itself has a pump tilt angle qp. A configuration that delays may be provided. That is, the torque control unit may delay the input torque. The first-order lag filter 55 may be enabled only when the pedal is operated such that an engine stall occurs.

  Although the said embodiment showed the example which ensures the acceleration property of the hydraulic motor 5 for driving | running | working at the time of vehicle travel, it is not limited to this, For example, even if applied to the hydraulic motor for turning which turns the upper turning body of a vehicle Good. Further, the input torque T2 is changed by controlling the regulator 30 of the variable displacement hydraulic pump 10, but not limited to this, even if another actuator having a function of changing the input torque T2 acting on the engine 20 is controlled. Good. In the above, a wheel-type hydraulic excavator has been described as an example of the construction machine, but the present invention can also be applied to construction machines other than the wheel-type. That is, the present invention is not limited to the road surface cleaning device of the embodiment as long as the features and functions of the present invention can be realized.

The figure which shows the external appearance of the wheel type hydraulic excavator applied to embodiment of this invention. The figure which shows the hydraulic circuit of the control apparatus concerning embodiment of this invention. The P-qp diagram of a variable displacement hydraulic pump. The figure which shows the full load performance curve of the engine applied to embodiment of this invention. The block diagram of the control apparatus concerning embodiment of this invention. The figure explaining the detail of the control circuit of an input torque. The figure which shows the characteristic of the primary delay filter 55 of FIG. The figure explaining the detail of the control circuit of an engine speed, The flowchart which shows the control procedure of an engine speed. The figure which shows the operating characteristic by the control apparatus concerning embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Hydraulic pump 14a Traveling pedal 23 Pulse motor 24 Potentiometer 30 Regulator 36 Pressure sensor 40 Controller 40A Torque control part 40B Rotation speed control part 43 Reference torque calculation part 55 Primary delay filter

Claims (2)

A variable displacement hydraulic pump having a function of changing an input torque acting on the prime mover and driven by the prime mover ;
A rotational speed setting means for setting a target rotational speed of the prime mover;
A rotational speed control means for controlling the rotational speed of the prime mover according to the target rotational speed set by the rotational speed setting means;
Input torque control means for controlling the input torque according to the target rotational speed so that the input torque acting on the prime mover is delayed with respect to the change of the target rotational speed ,
The input torque control means includes
A rotational speed delay unit that outputs a target rotational speed for torque control based on the target rotational speed set by the rotational speed setting means with a delay;
A torque calculation unit for calculating a target input torque according to the target rotation number output from the rotation number delay unit;
A construction machine control device comprising: a torque control unit that controls an input torque of the hydraulic pump to a target input torque calculated by the torque calculation unit . The control device for a construction machine according to claim 1 ,
The rotation speed delay unit outputs a target rotation speed for torque control with a first-order delay.

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