JP2008144628A - Working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable both of deceleration operation to an idling condition during machine body stop and restoration operation to constant speed before deceleration operation with simple human work operation in work during constant speed travel. <P>SOLUTION: This vehicle is provided with an operation switch 50a with which a command for changing engine speed can be input to a control means 100 outputting a control command to an engine speed regulating device 31 separately from an human work operation means 28 for changing and establishing engine speed to optional speed. Engine speed established by a speed retaining mechanism is decelerated to and retained in the idling condition based on detection of operation of the operation switch 50a, and engine speed is restored to the speed established right before deceleration by re-operation of the operation switch 50a or operation of another release means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a work vehicle such as a tractor or a front loader that is used for working while maintaining an engine at a constant speed such as rated rotation.

  As a work vehicle that operates at a constant speed with the accelerator set so that the engine speed is maintained at a constant speed such as the rated speed, a hand accelerator lever that can hold the position is generally used, and the holding position of the hand accelerator lever is set. Some are configured to run at a constant speed at a corresponding speed. However, simply running at a constant speed has the disadvantages that the fuel consumption is large and the noise is high because the engine is maintained at high speed rotation even at low loads when the aircraft is temporarily stopped.

Conventionally, the following technical means are known as means for solving such problems.
That is, a vehicle speed sensor that generates a signal proportional to the actual vehicle speed, a command switch that outputs a cruise command signal, a vehicle speed storage unit that stores a vehicle speed when the command switch is operated, and a motor-driven actuator that drives a throttle valve The cruise command signal based on the operation of the command switch is input to the control device to perform constant speed running, and the actuator driving motor is moved in the deceleration direction of the throttle valve as the brake pedal is operated. The control based on the cruise command is canceled, and the throttle valve is returned to the neutral position to be in the idling state (see, for example, Patent Document 1).

JP-A-61-287830 (Gazette Specification, page 4, upper left column, upper right column, lower left column, FIGS. 2 and 4)

  In a work vehicle such as a tractor that works while maintaining a constant engine speed, engine stall may occur in advance if the engine speed is too low, because engine stall may occur depending on the magnitude of load fluctuation. However, at light loads such as when the airframe is stopped, the engine speed is too high, resulting in poor fuel efficiency.

  Therefore, as in the technique disclosed in Patent Document 1, control for detecting that the brake pedal is depressed and returning the engine speed to the idling state has been adopted. In this way, returning the engine speed to the idling state in connection with the aircraft stop operation is effective in improving the fuel efficiency described above, but it is possible to restore the engine speed to the intended constant speed state again. Therefore, it is necessary to perform a troublesome operation of performing the accelerator setting while resuming the work traveling and grasping the engine speed during the acceleration of the airframe.

  An object of the present invention is to perform a deceleration operation to an idling state when the aircraft is stopped and a restoration operation to a constant speed before the deceleration operation, both by a simple human operation when performing a work at a constant speed. It is to provide a work vehicle that can be used.

The technical means of the present invention taken in order to achieve the above object has the following structural features and operational effects.
[Solution 1]
While equipped with an artificial operating tool for changing and setting the engine rotation speed to an arbitrary rotation speed, and a rotation speed maintenance mechanism for running the work while maintaining the engine rotation speed at a constant rotation speed,
In a work vehicle comprising control means for outputting a control command to an engine speed adjusting device of the speed maintaining mechanism so as to maintain the engine speed set by the human operation tool,
In addition to the artificial operation tool, an operation switch capable of inputting an engine rotation speed change command to the control means,
The control means, based on the detection that the operation switch has been operated, reduces and maintains the engine speed set by the rotation speed maintenance mechanism to an idling state or a rotation speed close to this, And it is comprised so that it may restore to the engine speed set immediately before the said operation switch is operated by the operation of the said operation switch again, or operation of the other cancellation | release means.

[Operation and effect of invention according to Solution 1]
According to the configuration shown in the above solution 1, the engine speed adjustment is performed so that the engine speed is reduced to an idling state or a speed close to the idling state during the work traveling at the set speed by the speed maintaining mechanism. An operation switch for instructing the control means of the apparatus is provided, and the operation switch is provided separately from a human operation tool for changing and setting the engine speed to an arbitrary speed.
In other words, by operating the operation switch when the aircraft is stopped, the engine speed can be easily reduced to the idling state. It does not affect the man-made operating tools provided. Therefore, when restoring the engine speed reduced by the operation switch, it is easy to restore the engine speed set before the reduction by simply releasing the engine speed reduction action by the operation switch. It can be done reliably by operation.

[Solution 2]
According to a second aspect of the present invention, in the work vehicle according to the first aspect, the work vehicle includes an accelerator pedal for changing the engine speed to an arbitrary speed, and based on detection of the operation switch being operated, The present invention is characterized in that the control by the operation signal of the accelerator pedal is disabled.

[Operation and effect of invention according to Solution 2]
According to the configuration shown in the solution means 2, it is based on the detection that the operation switch is operated while the accelerator pedal is provided and the engine speed can be arbitrarily changed by the accelerator pedal. Thus, the control by the operation signal of the accelerator pedal is made impossible. Therefore, even when the operation switch is operated and the idling state is maintained, even if the accelerator pedal is depressed by mistake, there is no problem that the engine speed increases unexpectedly.

[Solution 3]
According to a third aspect of the present invention, the work vehicle according to the first or second aspect further comprises a travel mode switching operation tool capable of switching a travel mode between a work travel mode and a road travel mode, and the road travel mode is selected. Then, there is a feature in that the control by the detection signal that the operation switch is operated is disabled.

[Operation and effect of invention according to Solution 3]
According to the configuration shown in the solution means 3, when the road travel mode is selected from the work travel mode and the road travel mode, the control based on the detection signal indicating that the operation switch has been operated becomes impossible.
In other words, while using the road travel mode, it is not necessary to perform constant speed travel as in the work travel mode, so that the operation itself using the operation switch is unnecessary. In this solution 3, by disabling the control by the detection signal of the operation switch in the road running mode, there is no inconvenience that the engine speed is suddenly reduced to the idling state even if the operation switch is erroneously operated. Therefore, there is an advantage that it is possible to reduce problems caused by an erroneous operation during the road running mode.

[Solution 4]
According to a fourth aspect of the present invention, in the work vehicle according to any one of the first to third aspects, a travel mode switching operation tool capable of switching a travel mode between a work travel mode and a road travel mode. When the road running mode is selected, the control based on the detection signal indicating that the artificial operating tool for changing and setting the engine speed to an arbitrary speed is disabled. There is a feature.

[Operations and effects of invention according to Solution 4]
According to the configuration shown in the solution means 4, when the road traveling mode is selected from the work traveling mode and the road traveling mode, the human operation tool for changing and setting the engine rotational speed to an arbitrary rotational speed is operated. Control by the detection signal of being done becomes impossible.
In other words, while using the road driving mode, it is not necessary to perform constant speed driving as in the work driving mode, so the human operation itself for changing the engine speed to an arbitrary speed is set. It is unnecessary. In this solution 4, the engine speed is maintained at a constant speed even if the artificial operating tool is erroneously operated by disabling control by the detection signal of the artificial operating tool in the road running mode. Can avoid inconvenience. Therefore, there is an advantage that it is possible to reduce problems caused by an erroneous operation during the road running mode.

Hereinafter, an example of an embodiment of the present invention will be described based on the drawings.
〔overall structure〕
FIG. 1 shows an entire side surface of a tractor which is an example of a work vehicle. This tractor has a clutch housing 3 connected to a rear end portion of an engine 2 mounted and supported on a front frame 1. 3 is connected to a hydrostatic continuously variable transmission (an example of a hydraulic continuously variable transmission) 4 employed as a main transmission, and a transmission case is connected to the rear end of the hydrostatic continuously variable transmission 4. 5 is connected to form a body frame 6.

  A driving portion is formed in the front half of the fuselage frame 6, a boarding operation portion 7 is formed in the latter half of the fuselage frame 6, and steering is configured to allow transmission of engine power to the front lower portion of the fuselage frame 6. A pair of left and right front wheels 8 are provided, and a pair of left and right rear wheels 9 configured to be capable of transmitting engine power are provided in the lower rear portion of the body frame 6. A pair of left and right lift arms 10 and a link mechanism 11 that enable connection of various work devices (not shown) are provided at the rear end of the machine body frame 6, and work devices that are connected and connected via the lift arms 10 and the like. A power take-out shaft 12 is provided that allows the engine power to be taken out.

As shown in FIGS. 1 and 2, the power from the engine 2 is transmitted to a hydrostatic continuously variable transmission 4 via a dry single plate main clutch 13 built in a clutch housing 3, and this hydrostatic type. Power after shifting by the continuously variable transmission 4 is output from the motor shaft 4a.
The power output from the motor shaft 4a of the hydrostatic continuously variable transmission 4 is transmitted to the gear transmission 14 employed as the first auxiliary transmission in the transmission case 5 as traveling power, The gear transmission 14 is configured to be transmitted to the second auxiliary transmission 15.

  The second sub-transmission device 15 includes a work speed switching mechanism 15A having two sets of gears and one synchromesh type shift member 45 so as to switch the work speed between high and low, and the work speed switching mechanism 15. The overdrive transmission mechanism 15B having a set of gears and a synchromesh type shift member 46 disposed on the lower transmission side of the transmission and the state in which the transmission state from the work speed switching mechanism 15A is transmitted as it is and the speed is greatly reduced. And a creep transmission mechanism 15 </ b> C having a constant mesh type shift member 47.

Power is transmitted from the bevel gear provided at the end of the second auxiliary transmission 15 to the rear wheel differential 16 and the power output from the rear wheel differential 16 is used for driving the rear wheels. 9 is transmitted.
Further, the power output via the front wheel clutch 48 immediately before the bevel gear provided at the end of the second auxiliary transmission 15 is used for driving the front wheels, such as the front wheel transmission shaft 17 and the front wheel differential 18. To the left and right front wheels 8.

  As shown in FIGS. 1 and 3, the boarding operation unit 7 is supported by a boarding step 21 connected to the left and right of the body frame 6 and a steering post 22 erected on the front upper part of the hydrostatic continuously variable transmission 4. A steering wheel 23, an accelerator pedal 29 disposed on the right side of the steering post 22, a pair of left and right brake pedals 24, a transmission pedal 26 disposed on the right side of the body frame 6, and a rear upper portion of the transmission case 5. The driver's seat 27 is provided.

As shown in FIGS. 3 and 4, an operation panel switching operation tool 25 of the second auxiliary transmission device 15 is provided on the operation panel portion arranged on the left side portion of the driver seat 27.
The travel mode switching operation tool 25 includes an intermediate speed work travel mode that transmits the output from the work speed switching mechanism 15A of the second auxiliary transmission device 15 to the rear wheel actuator 16, and an overdrive transmission mechanism 15B. The traveling mode is set to each state of a high-speed road traveling mode that transmits the output of the rear wheel to the rear wheel actuator 16 and an extremely low speed creep traveling mode that transmits the output from the creep transmission mechanism 15C to the rear wheel actuator 16. It is configured to be freely switchable.

  As shown in FIG. 4, the traveling mode switching operation tool 25 includes an overdrive position H for traveling on the road, a high-speed working position M2 that is slower than the traveling on the road and that is relatively high in working speed, and the high-speed working position. It is configured to be freely switchable between the operation positions of the low-speed work position M1 that is lower than M2 and the slowest creep travel position L. Then, the shift members 45, 46, 47 corresponding to the respective operation positions are sequentially switched by the operation of the shift cylinder (not shown) and the travel mode is changed by being operated to the respective operation positions. Has been.

On the other hand, the non-transmission power output from the pump shaft 4b of the hydrostatic continuously variable transmission 4 uses, as working power, the wet multi-plate type PTO clutch 49 and the PTO transmission 20 incorporated in the mission case 5. Is transmitted to the power take-off shaft 12 via
As shown in FIGS. 3 and 4, a PTO speed change lever 19 is provided on the operation panel portion disposed on the right side of the driver's seat 27 so as to be swingable forward and backward and left and right. The PTO speed change lever 19 can be changed from the first speed to the fourth speed by switching the shift members 20A and 20B of the PTO speed change device 20 with a shift cylinder (not shown). By operating a push button 19a provided on the top of the grip portion of the lever 19, a control valve for controlling the supply of pressure oil to the operation piston of the PTO clutch 49 located on the transmission upper side of the PTO transmission 20 is operated, and the PTO The clutch 49 is configured to be able to be switched intermittently by a button operation.

[Running operation mechanism]
FIG. 4 is a block diagram of a traveling operation mechanism provided in the tractor.
As shown in this figure, the traveling operation mechanism includes a hydraulic transmission cylinder 42 (hereinafter, abbreviated as a transmission cylinder 42) for shifting the hydrostatic continuously variable transmission 4 and an accelerator device 30 for the engine 1. An electric actuator 31 (hereinafter referred to as an accelerator actuator 31) as an engine speed control device to be operated and a control means linked to the accelerator actuator 31 and linked to a servo control mechanism 43 that controls the shift cylinder 42. 100.
The travel operation mechanism includes a speed change pedal 26 provided in the boarding operation unit 7, an accelerator lever 28 as an artificial operation tool for changing and setting the engine speed to an arbitrary speed, an accelerator pedal 29, and the speed change pedal 26. Rotation potentiometer 36 (hereinafter referred to as pedal sensor 36) serving as a sensor for outputting the detected operation position information to the control means 100, and the detected information on the operation position of the accelerator lever 28 to the control means 100. A rotary potentiometer 28a (hereinafter referred to as an accelerator lever sensor 28a) as an output sensor and a rotary potentiometer 29a (a sensor that outputs detection information of the operation position of the accelerator pedal 29 to the control means 100). Hereinafter, it is referred to as an accelerator pedal sensor 29a).

  The transmission cylinder 42 is installed inside the transmission case 5 and changes the hydrostatic continuously variable transmission 4 by changing the swash plate angle of the hydraulic pump 40. As shown in FIG. 4, the servo control mechanism 43 includes a forward proportional control valve 44 and a reverse proportional control valve 45, and the forward proportional control valve 44 and the reverse proportional control valve 45 are switched according to a command from the control means 100. Then, the shift cylinder 42 is operated so that the hydrostatic continuously variable transmission 4 enters a shift state corresponding to the operation position of the shift pedal 26. The servo control mechanism 43 is provided in the mission case 5.

  The control means 100 is configured using a microcomputer, and detects a shift state of the hydrostatic continuously variable transmission 4 based on information detected by the pedal sensor 36 and a swash plate angle. On the basis of the detected information, the variable speed cylinder 42 is operated via the servo control mechanism 43 so that the hydrostatic continuously variable transmission 4 enters a shift state corresponding to the operation position of the shift pedal 26.

Based on the detection information by the accelerator lever sensor 28 a and the detection information by the accelerator sensor 32 that detects the operation state of the accelerator device 30, the control means 100 determines the rotational speed at which the accelerator device 30 corresponds to the operation position of the accelerator lever 28. The accelerator actuator 31 is operated so as to be in an operation state for causing the engine 1 to appear.
The accelerator lever 28 is configured such that its operation position is held by a well-known friction holding mechanism (not shown), the accelerator lever 28, an accelerator lever sensor 28a for detecting the position of the accelerator lever 28, and an accelerator device. The accelerator sensor 32 for detecting the operation state of 30, the control means 100, and the accelerator actuator 31 constitute a rotation speed maintaining mechanism for keeping the engine speed constant and performing work travel.

  In driving the tractor, when the speed change pedal 26 is depressed from the neutral state to the front side of the vehicle body (clockwise in the figure), the control means 100 operates the speed change cylinder 42 to the forward side and the hydrostatic continuously variable transmission 4. Is shifted forward and the tractor travels forward. When the shift pedal 26 is depressed from the neutral state toward the rear of the vehicle body (counterclockwise in the figure), the control means 100 operates the shift cylinder 42 to the reverse side and the hydrostatic continuously variable transmission 4 shifts to the reverse side. Operated, the tractor travels backward. In both forward travel and reverse travel, as the depression stroke of the shift pedal 26 is increased, the control means 100 operates the shift cylinder 42 to the higher speed side and the hydrostatic continuously variable transmission 4 shifts to the higher speed side. Operated, the tractor travel speed increases.

[Forced idling operation]
As shown in FIGS. 3 and 4, a push button switch (operation switch) as a forced idling operation tool 50 for inputting an operation signal to the control means 100 so as to forcibly reduce the engine speed to an idling state. Example) 50a is provided on the front panel 7A of the boarding operation unit 7. When the control means 100 detects that the push button switch 50a has been pressed, the engine speed is controlled based on the speed control means 101 stored as a program in the control means 100.

That is, as shown in FIG. 4, when a signal indicating that the push button switch 50a has been pressed is detected, the control means 100 is programmed as a program so that the engine speed is reduced to an idling speed. A control command is output from the stored speed control means 101 to the accelerator actuator 31, and the accelerator device 30 is operated to the low speed side to be in an idling state.
Based on the detection signal indicating that the push button switch 50a has been pressed, the control means 100 is operating on the display means such as the indicator 70 provided on the front panel 7A by the forced idling operation. It is configured to output a signal for lighting display or displaying character data or a display mark.
It should be noted that the engine speed reduced by detecting that the push button switch 50a has been pressed is preferably the engine speed corresponding to the idling state as described above. The number of revolutions may be a little higher than the idling state as long as the range does not have a large influence.

According to the forced idling operation described above, the operation position of the accelerator lever 28 as the accelerator operating tool has not changed, so that the detection signal from the accelerator lever sensor 28a is input to the control means. As long as the detection signal from 28a does not change, this is ignored and the forced idling operation by the pressing operation of the push button switch 50a is performed.
When the engine speed is reduced to the idling state, the engine speed is restored based on the operation of the push button switch 50a again or the detection of the operation of the accelerator lever 28, or a separately provided engine speed. Based on the operation of the dedicated operation tool, the engine speed is controlled to increase, and the engine speed is recovered so that it becomes the engine speed based on the detection signal of the accelerator lever sensor 28a.

[Control form]
The engine speed control operation when the forced idling operation tool 50 is used will be described with reference to the flowcharts of FIGS.
[1] FIG. 5 shows a main routine for engine speed control. First, immediately after the engine is started, the flag value (F = 0) is read as an initial set (step # 1).
[2] Next, the value of the engine speed detector 33 is read to detect the actual engine speed (step # 2).
[3] Next, the detection signal of the accelerator lever sensor 28a is read, and the constant speed rotational speed set by the accelerator lever 28 is detected (step # 3).
[4] Next, the operation position signal of the travel mode switching operation tool 25 is read to detect the mode selected by the travel mode switching operation tool 25 (step # 4).
[5] It is detected whether or not the mode selected by the travel mode switching operation tool 25 is the road travel mode H. If the road travel mode H is not selected, the next process is performed. If there is, control is not performed. (Step # 5).
[6] If the accelerator set value detected by the accelerator lever sensor 28a is larger than 0, that is, if the accelerator is set, the next process is performed, and if it is 0, no control is performed (step # 6). ).
[7] If the rotational speed detected by the engine rotational speed detector 33 is larger than the rotational speed corresponding to the idling state, the next process is performed. If not, the control is not performed (step # 7).
[8] If the push button switch 50a of the forced idling operation tool 50 is OFF, work travel control is performed to control the engine speed so that it is driven at a constant speed set by the accelerator lever 28, and the push button switch If 50a is ON, forced idling control is performed. The work travel control is a normal constant speed travel that is controlled so that the target engine speed corresponding to the detection signal of the accelerator lever sensor 28a is equal to the actual engine speed detected by the engine speed detector 33. Since it is control, the description here is omitted (steps # 8, # 9, # 10).

The forced idling control is performed as shown in FIG.
[9] First, the value of the flag is read. If the value of the flag is (F = 0), the control means 100 performs control so as to ignore the value of the detection signal from the accelerator pedal sensor 29a, and the engine rotation. Control to forcibly reduce the number. If the flag value is (F = 1), control for increasing the engine speed is performed without performing control to ignore the value of the detection signal from the accelerator pedal sensor 29a (steps # 12, # 13, #). 14, # 19).
[10] When the engine speed detected by the engine speed detector 33 reaches the engine speed stored in advance as the engine speed in the idling state, the idling state is maintained and the flag is set to (F = 1). Rewrite (steps # 15 and # 16).
[11] It is monitored whether or not the forced idling operation tool 50 has been operated, and when the forced idling operation tool 50 is operated again, control is performed to permit the control means 100 to accept the detection signal of the accelerator pedal sensor 29a. If it is not operated, processing is performed to detect whether or not the value of the accelerator lever sensor 28a has changed (steps # 17, # 18, and # 22).
[12] It is detected whether or not the value of the accelerator lever sensor 28a has changed. If the value has changed, the control means 100 is allowed to accept the detection signal of the accelerator pedal sensor 29a. Returning to the previous stage of step # 16, the detection is continued again (steps # 18 and # 22).
[13] The engine speed is increased, and when the engine speed detected by the engine speed detector 33 is equal to the engine speed corresponding to the detection signal of the accelerator lever sensor 28a, the engine speed increase control is terminated. Then, the value of the flag is rewritten to (F = 0) (steps # 19 and # 20).
[14] When the forced idling operation tool 50 is operated again or when the value of the accelerator lever sensor 28a changes, the control means 100 side is allowed to accept the detection signal of the accelerator pedal sensor 29a that has been temporarily stopped. The forced idling control is terminated and the process returns (step # 22).
[15] When the forced idling control or the constant speed running control is finished, it is determined whether or not the engine is stopped by a key switch operation. If the engine is not stopped, a step between Step # 1 and Step # 2 is performed. The control is repeated after returning to (# 11).

[Another embodiment]
[1] The position where the push button switch 50a is provided is not limited to the above-described front panel 7A, and may be any place that can be easily operated by the driver during traveling work. For example, the push button switch 50a is provided in the operation box 7B beside the driver seat 27. May be.

[2] The forced idling operation tool 50 is not limited to the push button switch 50a, but may be a changeover switch that can be switched by a swinging operation, but is configured with a operability that is as good as possible, such as a one-touch operation. It is desirable.

[3] The work vehicle according to the present invention is not limited to the structure having the hydrostatic continuously variable transmission 4 shown in the above-described embodiment as the speed change structure of the main speed change apparatus, but is also a gear transmission or a hydraulic clutch. A transmission structure using a combination of a gear and a constant-gear gear, or a transmission structure using CVT or the like may be employed.

[4] The present invention can be applied to various work vehicles such as mowers in addition to tractors. Therefore, these tractors, mowers, etc. are collectively referred to as work vehicles.

Side view of the entire tractor Power transmission diagram showing the transmission structure of the tractor in FIG. Plan view showing boarding operation part Block diagram showing control means and input / output devices in the traveling operation mechanism Flow chart showing control mode Flow chart showing control mode

Explanation of symbols

2 Engine 4 Hydrostatic continuously variable transmission 19 PTO transmission lever 20 PTO transmission 28 Accelerator lever 29 Accelerator lever sensor 30 Accelerator device 31 Accelerator actuator 42 Shift actuator 50 Forced idling operation tool 50a Push button switch 100 Control means 101 Speed control means

Claims (4)

While equipped with an artificial operating tool for changing and setting the engine rotation speed to an arbitrary rotation speed, and a rotation speed maintenance mechanism for running the work while maintaining the engine rotation speed at a constant rotation speed,
In a work vehicle comprising control means for outputting a control command to an engine speed adjusting device of the speed maintaining mechanism so as to maintain the engine speed set by the human operation tool,
In addition to the artificial operation tool, an operation switch capable of inputting an engine rotation speed change command to the control means,
The control means, based on the detection that the operation switch has been operated, reduces and maintains the engine speed set by the rotation speed maintenance mechanism to an idling state or a rotation speed close to this, In addition, the work vehicle is configured to restore the engine speed set immediately before the operation switch is operated by the operation of the operation switch again or the operation of other release means.   An accelerator pedal for changing the engine speed to an arbitrary speed is provided, and the control based on the operation signal of the accelerator pedal is disabled based on the detection that the operation switch is operated. The work vehicle according to claim 1.   A travel mode switching operation tool capable of switching the travel mode between the work travel mode and the road travel mode is provided. When the road travel mode is selected, the control based on the detection signal indicating that the operation switch is operated is disabled. The work vehicle according to claim 1 or 2, which is configured as described above.   It is equipped with a travel mode switching operation tool that can switch the travel mode between the work travel mode and the road travel mode, and when the road travel mode is selected, an artificial operation for changing and setting the engine speed to an arbitrary speed The work vehicle according to any one of claims 1 to 3, wherein the work vehicle is configured to be disabled by a detection signal indicating that the tool has been operated.

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