JP3942948B2 - Swing control device for work machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a turning control device for a working machine such as a hydraulic excavator or a crane that drives a turning body by an electric motor.
[0002]
[Prior art]
An explanation will be given using an excavator as an example.
[0003]
As shown in FIG. 9, the excavator has an upper swing body 2 mounted on a crawler-type lower traveling body 1 so as to be rotatable about a vertical axis O. A boom 3, an arm 4, and a bucket 5 are mounted on the upper swing body 2. The excavation attachment A including the cylinders 6, 7, and 8 for the boom, arm, and bucket is mounted.
[0004]
Recently, in this shovel, a system using an electric motor as a drive source has been proposed in place of or in addition to the conventional hydraulic drive, and a system using an electric motor as a drive source for a rotating body has also been proposed (for example, special Open 2001-10783).
[0005]
When the electric motor is used as the turning drive source in this manner, normally, feedback speed control is performed to control the speed of the electric motor based on the difference between the target value of the turning speed corresponding to the operation amount of the operating means and the actual value. .
[0006]
[Problems to be solved by the invention]
However, according to the turning control method using only this feedback speed control, the following problems occur.
[0007]
FIG. 10 shows a free-turning state in which the upper-part turning body 2 is normally turned on the ground. During normal operation in which this free-turning is performed, the turning speed control according to the operation amount of the operating means can be performed by the feedback speed control method. Because there is no problem in operation.
[0008]
On the other hand, as shown in FIG. 11, during the pressing operation in which the side surface of the bucket 5 is pressed against the wall surface 9a of the groove 9 in the direction of the arrow to form the wall surface 9a, the turning speed becomes substantially zero. The deviation between the target value and the actual value becomes larger, and the turning torque (motor torque) becomes maximum even with a small amount of operation due to the feedback action.
[0009]
For this reason, the torque control by the operator becomes impossible during the pressing operation by such turning, and the operability is impaired.
[0010]
Accordingly, the present invention provides a turning control device for a work machine that can improve the operability by enabling the turning torque control during the pressing operation in the electric motor drive system.
[0011]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided an electric motor for driving the turning body, an operating means for issuing a turning command, a control means for controlling the electric motor based on the turning command from the operating means, and a turning speed for detecting the turning speed. In a turning control device for a work machine that includes a detecting means and performs speed control according to an operation amount of the operating means by the control means, the control means presses a part of the turning body against a work target. Instead of the speed control, torque control according to the operation amount of the operation means is performed when it is determined that the working state is established.
[0012]
According to a second aspect of the present invention, there is provided an electric motor for driving the turning body to turn, an operating means for issuing a turning command, a control means for controlling the electric motor based on the turning command from the operating means, and a turning speed for detecting the turning speed. In a turning control device for a work machine that includes a detecting means and performs speed control according to an operation amount of the operating means by the control means, the control means presses a part of the turning body against a work target. When it is determined as a working state, control is performed by adding a torque limit corresponding to the operation amount of the operation means to the speed control.
[0013]
According to a third aspect of the present invention, in the configuration of the second aspect , the control means is configured to determine the pressing work state when the actual value of the turning speed is smaller than a target value corresponding to the operation amount of the operation means. It is a thing.
[0014]
The invention according to claim 4, in the construction of claims 1 to 3, the control means is a greater state than start moving the turning operation amount of the operation means position, the actual value of the rotation speed is close to zero set value It is comprised so that it may be judged as a pressing work state at the following times.
[0015]
A fifth aspect of the present invention is the structure according to any one of the first to fourth aspects, wherein the target torque is a value larger than 0 in a state where the operating means is at the turning start position. .
[0016]
According to the above configuration, at the time of pressing work, the torque control corresponding to the operation amount in place of the speed control in accordance with the operation amount of the operation means is performed (claim 1), or the control plus torque limit to the speed control (Claims 2 and 3 ) .
[0017]
Ie, by either configuration, at the time of pressing work, it is possible to control the turning torque in accordance with the operation amount of the operation means, operability during the pressing work is improved.
[0018]
Moreover, automatically switched to automatically torque control or torque limited speed control determines the working condition pressing the control means.
[0019]
For this reason, the operator is compared to the system such as operating the control change-over switch, it is possible to control in a fully automatic when working pressing for example.
[0020]
In time and, when operated slightly larger than the swirl start moving position operating means from turning stop state, the actual value of the speed by the inertia of the swiveling body (becomes zero or a value close thereto) is smaller than the target value for the free Even in the turning state, the torque control works in claim 1, and the speed control with torque limitation works in claims 2 and 3 .
[0021]
In this case, according to the fifth aspect of the present invention, the target torque (the torque target value in the torque control system, the torque limit value in the speed control system with torque limitation) is 0 when the operating means is in the turning start position. Therefore, when the operating means is operated slightly larger than the turning movement starting position as described above, the turning torque is immediately applied, and the turn-up starts quickly and the speed is quickly switched to the speed control. For this reason, the operability at the beginning of movement is good.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
[0023]
1st Embodiment (refer FIGS. 1-6)
FIG. 1 is an overall configuration diagram of a turning control device according to this embodiment.
[0024]
In the figure, reference numeral 11 denotes an operation lever as an operation means. An operation direction and an operation amount of the operation lever 11 are converted into an electric signal by a signal converter 12 and input to a controller 13 which is a control means.
[0025]
Reference numeral 14 denotes an engine, and 15 denotes a generator driven by the engine 14. The electric power from the generator 15 is sent to the swing motor 18 via both inverters 16 and 17 for the generator and the swing motor. The rotational force of the electric motor 18 is transmitted to the upper swing body 2 via the speed reducer 19, and the swing body 2 rotates about the vertical axis O in FIGS.
[0026]
Reference numeral 20 denotes an encoder as a turning speed detecting means for detecting the rotation speed of the turning electric motor 18. The electric motor rotation speed detected by the encoder 20 is input to the controller 13 as an actual value of the turning speed.
[0027]
In addition to the generator 15, a battery 21 and a capacitor 22 are provided as a power source for the swing motor 18, and these power sources are appropriately selected or combined for use. Alternatively, power may be supplied from an external power source instead of the internal power source. Reference numeral 23 denotes a battery inverter, and reference numeral 24 denotes a capacitor inverter.
[0028]
Further, a hydraulic pump 26 is provided as a hydraulic source of a hydraulic actuator circuit 25 that drives hydraulic actuators such as the cylinders 6, 7, 8, etc. of the excavation attachment A, and the hydraulic pump 26 is driven by a pump electric motor 27. 28 is an inverter for the same motor.
[0029]
The controller 13 controls the speed of the swing motor 18 by the speed PID feedback control shown in FIG. 2 during the free turn shown in FIG.
[0030]
That is, the operation amount S of the operation lever 11 is input to the controller 13 as an operation amount signal through the signal converter 12, and the controller 13 calculates the target value ωref of the turning speed corresponding to the lever operation amount S.
[0031]
The target value ωref is compared with the actual value ωs of the turning speed detected by the encoder 20 to obtain a deviation, and a signal in a direction to make the deviation (ωref−ωs) zero by PID feedback control is an inverter for the motor. 17 to the electric motor 18.
[0032]
Thereby, as shown in FIG. 3, the upper swing body 2 rotates at a speed corresponding to the lever operation amount S. In FIG. 3, Sc is a lever position at which the revolving unit 2 starts to move.
[0033]
In FIG. 2, for the sake of convenience, the output of the encoder 20 is represented as the actual value ωs of the turning speed. However, in practice, the electric motor rotation speed is detected by the encoder 20 and divided by the reduction ratio of the speed reducer 19. ωs is determined.
[0034]
On the other hand, torque control is performed during the pressing operation shown in FIG.
[0035]
That is, as a procedure for determining whether or not it is a pressing operation, the controller 13 compares the lever operation amount S and the turning movement start position Sc at each control cycle b as shown in FIG. 4 (steps S1 and S2). At the same time, the actual value ωS of the turning speed is compared with the threshold value ωe shown in FIG. 3 set in advance as a minute value close to 0 (step S3), and the lever operation amount S is larger than the movement start position Sc. In addition, when the actual value ωs of the turning speed is smaller than the threshold value ωe (YES in both steps S2 and S3), it is determined that the pressing operation is performed, and the torque control is automatically switched to (step S4). ), The control cycle b is updated in step S5, and the process returns to step S1. If NO in step S2 or step S3 (S <Sc or ωS> ωe), the feedback speed control shown in FIGS. 2 and 3 is performed as a free turn (step S6).
[0036]
In addition, when the pressing work object is uneven or soft, the turning speed may be 0 or more, and hunting may occur without the determination of the pressing work being stabilized. In such a case, it is desirable to provide hunting suppression means such as reducing the feedback gain of speed control or giving a time lag to the switching of the determination.
[0037]
In the torque control, as shown in FIGS. 5 and 6, the torque target value ref is obtained from the operation amount-torque map 29 in which the relationship between the lever operation amount S and the torque target value τref is set, and this is converted into the current target value iref. Thus, torque PID feedback control is performed.
[0038]
In this way, the pressing operation is automatically determined and switched to torque control. By this torque control, an electric motor torque corresponding to the lever operation amount S is obtained as shown in FIG. It is possible to control according to (operation amount).
[0039]
By the way, according to this control method, when the lever 11 is placed slightly deeper than the movement start position Sc in FIG. 6 from the state where the lever is neutral and the turning speed is 0, the speed is 0 due to the inertia of the turning body 2. Torque control is automatically started even in the free turning state.
[0040]
Here, in this apparatus, as shown in FIG. 6, the torque target value τref at the movement start position Sc is set to a large value τc larger than zero.
[0041]
In this way, the turning torque τc works at the movement start position Sc, and when the lever 11 is inserted slightly deeper than the movement start position Sc as described above, the turning operation is started quickly, so that the actual speed value ωs is the target value. Quickly reaches ωref and switches to speed feedback control. For this reason, speed controllability at the start of movement can be improved.
[0042]
Second embodiment (see FIG. 7)
Only differences from the first embodiment will be described.
[0043]
In the second embodiment, as in the first embodiment, the speed feedback control according to the flow of FIG. 5 is performed at the time of free-turning, and at the time of pressing work, as shown in FIG. Based on the torque limit value map 30, control (torque limited speed control) is performed in which a torque limit corresponding to the lever operation amount S is added.
[0044]
Τlim shown on the vertical axis of the map 30 in FIG. 7 is a torque limit value.
[0045]
Thus, by performing speed control with torque limitation during the pressing operation, the motor torque corresponding to the lever operation amount can be obtained as in the case of the torque control of FIGS. Similar to the above, the operability during the pressing operation is good.
[0046]
In the second embodiment and the next third embodiment as well, by setting the torque limit value τlim at the movement start position Sc to a value τc larger than 0, the movement is the same as in the first embodiment. The initial speed controllability can be improved.
[0047]
Third embodiment (see FIG. 8)
In the third embodiment, as shown in FIG. 8, when the actual speed value ωs is smaller than the target value ωref, it is determined as a so-called power running state, and in this power running state, speed feedback with torque limitation is performed from the speed feedback control. It is configured to switch to control.
[0048]
More specifically, the speed target value ωref and the actual value ωs are compared for each control period b (steps S1 and S2). When ωref ≦ ωs, normal speed feedback control is performed (step S3).
[0049]
On the other hand, if ωref> ωs (YES in step S2), it is determined as a power running state, and the control is automatically switched to the speed control with torque limitation of the second embodiment (FIG. 7) (step S4), and the control is performed in step S5. The period b is updated and the process returns to step S1.
[0050]
Accordingly, during the pressing operation, which is a kind of power running state, the motor torque is controlled by the torque limiting action as in the second embodiment.
[0051]
Further, according to this control method, even when accelerating in free-turning, the speed control action with torque limitation works in a situation where the actual value ωs of the turning speed is smaller than the target value ωref. Shock is reduced.
[0052]
In addition, since torque limitation does not work during deceleration, it is possible to decelerate at the maximum torque, and emergency stop is possible.
[0053]
Therefore, operability is also good in this respect.
[0054]
By the way , the present invention is not limited to shovels, and can be widely applied to swivel work machines such as deep hole excavators, crushers, cranes, and the like that are configured with a shovel as a base.
[0055]
【The invention's effect】
As described above, according to the present invention, during the pressing operation, torque control according to the operation amount is performed instead of the speed control according to the operation amount of the operation means (Claim 1), or torque limitation is added to the speed control. since the control was is performed (claim 2, 3), at the time of pressing work, it is possible to control the left to the turning torque of the operator's intention through operation of the operating means, is possible to improve the operability during the pressing work it can.
[0056]
Moreover, since the switched automatically switching to the torque control or torque limited speed control during pressing and with the work, it is possible to control fully automatically.
[0057]
According to the fifth aspect of the present invention to is found, in a state in which the operating means is in the start moving position turning, the torque as a target is set to a value greater than 0, slightly larger operation than start moving pivot the operating means located In this case, the turning torque is immediately applied, and the start of turning is quick and the speed control is quickly switched. For this reason, the operability at the beginning of movement is good.
[Brief description of the drawings]
FIG. 1 is a block configuration diagram of a control device according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a flow of speed feedback control by the apparatus.
FIG. 3 is a diagram showing a relationship between a lever operation amount and a speed target value in the same control.
FIG. 4 is a flowchart for explaining the operation of the apparatus.
FIG. 5 is a diagram showing a flow of torque control by the same control.
FIG. 6 is a diagram showing a relationship between a lever operation amount and a torque target value in the same control.
FIG. 7 is a diagram illustrating a flow of speed control with torque limitation by the control device according to the second embodiment of the present invention.
FIG. 8 is a flowchart for explaining the operation of the control device according to the third embodiment of the present invention.
FIG. 9 is a schematic side view of an excavator that is an example to which the present invention is applied.
FIG. 10 is a front view of the shovel.
FIG. 11 is a front view showing a state where the bucket of the shovel is pressed against the wall surface of the groove.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2 Upper revolving body 11 Operation lever as operation means 12 Signal converter which converts operation of operation lever into electric signal 13 Controller as control means 18 Electric motor for turning 20 Encoder as turning speed detecting means 15 Electric power generation as electric power source of electric motor Machine 21 Same battery 22 Same capacitor

Claims (5)

An electric motor for driving the turning body to turn, an operating means for issuing a turning command, a control means for controlling the electric motor based on the turning command from the operating means, and a turning speed detecting means for detecting the turning speed, In the turning control device for a work machine that performs speed control according to the operation amount of the operation means by the control means, when the control means determines that it is in a pressing work state in which a part of the turning body is pressed against a work target. A turning control device for a work machine, characterized in that, instead of the speed control, torque control is performed according to an operation amount of the operation means. An electric motor for driving the turning body to turn, an operation means for issuing a turn command, a control means for controlling the electric motor based on the turn command from the operation means, and a turning speed detection means for detecting the turning speed, In the turning control device for a work machine that performs speed control according to the operation amount of the operation means by the control means, when the control means determines that it is in a pressing work state in which a part of the turning body is pressed against a work target. A turning control device for a work machine configured to perform control by adding a torque limit corresponding to the operation amount of the operation means to the speed control. 3. The work machine according to claim 2, wherein the control means is configured to determine the pressing work state when an actual value of the turning speed is smaller than a target value corresponding to an operation amount of the operation means . Control device. Control means includes a feature that the operation amount of the operation means in a greater state than start moving position turning, the actual value of the rotation speed is configured to determine the working state pressed when the set value or less close to 0 The turning control device for a work machine according to any one of claims 1 to 3 .   5. The turning control device for a working machine according to claim 1, wherein the target torque is a value larger than 0 in a state where the operating means is in a turning movement start position. .

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