JP3977697B2 - 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 work machine such as an excavator or a crane that drives a turning body by an electric motor.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a swivel work machine such as an excavator or a crane usually uses a hydraulic motor as a swivel drive source and employs a hydraulic motor drive system in which the hydraulic motor is driven by oil discharged from a hydraulic pump.
[0003]
When this hydraulic motor drive system is adopted, a control valve is provided between the hydraulic pump and the hydraulic motor, and the direction, pressure and flow rate are controlled by this control valve to control the operating direction, force and speed of the hydraulic motor. .
[0004]
However, this method has a problem that a large amount of energy is lost due to a large amount of hydraulic energy that is squeezed out by a control valve.
[0005]
Therefore, recently, an electric motor drive system using an electric motor as a turning drive source has been proposed (see, for example, JP-A-11-93210).
[0006]
In addition, in a climbing crane or a large electric excavator for mining, an electric motor drive system has been conventionally used for a turning operation.
[0007]
In these electric motor turning drive systems, the turning direction and the turning speed are controlled by changing the rotation direction and speed of the electric motor, and the energy efficiency can be greatly improved.
[0008]
On the other hand, when this electric motor turning drive method is adopted, a feedback speed control method is generally used in which the speed is controlled in a direction that eliminates the deviation between the target speed corresponding to the lever operation amount and the actual speed.
[0009]
[Problems to be solved by the invention]
When this speed control method is adopted, when the command speed is 0 at the neutral position of the lever, the braking torque is applied and the turning body stops, but once the motor rotation speed becomes 0, the torque that maintains this speed 0 ( Since the stop holding force is not output, a reliable stop holding action cannot be obtained.
[0010]
Therefore, it is conceivable to use position holding control (servo lock control = control for holding the swivel body in place based on a signal from the position sensor) as a control method for holding the stop.
[0011]
However, in this position holding control, there is a problem that energy loss is large because a current for holding the revolving body in a stopped state must always be supplied to the electric motor.
[0012]
On the other hand, as another stop and hold method, it is conceivable to employ a mechanical brake provided in a hydraulic drive type work machine.
[0013]
However, mechanical brakes originally have a structure that operates as a parking brake when the swinging body is stopped. If this is used as it is as a means for decelerating and stopping the motor in the motor-driven swinging system, the brakes are consumed significantly. However, there is a problem that the motion of the revolving body during deceleration / acceleration is jerky due to a shock of brake on / off, and a smooth turning stop / acceleration action cannot be obtained.
[0014]
It is possible to modify the mechanical brake for deceleration and stop holding, but this is not a good idea because the cost increases.
[0015]
Therefore, the present invention solves such a problem, can reliably hold the revolving body in a stopped state, can smoothly perform turning deceleration, stop and acceleration, and has an energy loss for holding the stop. There is also provided a turning control device for a working machine that can use an existing mechanical brake as it is.
[0016]
[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. The control means is provided with a neutral range obtained by adding a width to an absolute neutral point where the operation amount of the operation means is 0 in advance. In this neutral range, a mechanical brake section is set on the absolute neutral point side, and a position holding control section is set on the opposite side.
(I) operating the mechanical brake in the mechanical brake section in the neutral range;
(Ii) Stopping and holding the revolving body by performing position holding control in the position holding control section;
(Iii) performing speed control according to the operation amount of the operation means outside the neutral range;
(Iv) At the time of turning deceleration, the position holding control is started when the operation amount of the operating means is in the position holding control section and the turning speed is equal to or lower than a preset position holding control start speed. It is a thing.
[0017]
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. The control means is provided with a neutral range obtained by adding a width to an absolute neutral point where the operation amount of the operation means is 0 in advance. In this neutral range, a mechanical brake section is set on the absolute neutral point side, and a position holding control section is set on the opposite side.
Exercising the mechanical brake (a) mechanical brake section in the neutral range,
( B ) Stopping and holding the revolving body by performing position holding control in the position holding control section,
( C ) Perform speed control according to the operation amount of the operation means outside the neutral range ,
(D) At the time of turning deceleration, the position holding control is started when the operation amount of the operating means is in the position holding control section and the turning speed is equal to or lower than a preset position holding control start speed;
(E ) At the time of turning deceleration, the mechanical brake is operated when the operation amount of the operating means is in the mechanical brake section and the state where the turning speed is below the preset brake operating speed continues for the set time. It is configured.
[0018]
According to a third aspect of the present invention, in the configuration of the first or second aspect, a combined section in which a part of the mechanical brake section and the position holding control section in the neutral range overlap each other is set, and the control means is configured to those that are configured so that worked both position holding control action.
[0019]
According to the above configuration, since the mechanical brake operates in the turning stop state, it is not necessary to constantly supply the current for in-situ holding to the electric motor as in the case of stopping and holding by the position holding control, thereby saving energy. In addition, since the mechanical brake is operated in the stopped state, it is not necessary to modify the mechanical brake for deceleration, and the existing one can be used as it is.
[0020]
In addition, because position hold control works at the boundary with speed control, there is no risk that the brakes will be consumed violently as in the case of deceleration / stop using only the mechanical brake, and the mechanical brake is turned on / off during turning acceleration / deceleration. Smooth acceleration / deceleration action can be obtained without any shock.
[0021]
In this case, when the swivel deceleration, when the rotation speed falls below the speed set in advance, i.e., since the position holding control while sufficiently decelerated starts, large braking torque by the position holding control in the deceleration insufficient state There is no risk of overcurrent flowing through the motor and causing damage to the motor or circuit.
[0022]
Further, according to the configuration of the second aspect, when the vehicle is decelerated by turning, the mechanical brake is not immediately applied even when entering the mechanical brake section, and is applied when the state below the set speed (for example, speed 0) is continued. At the time of excavating and scooping earth and sand, turning and loading into a dump truck, when turning → stopping → turning continuously and repeatedly, it prevents mechanical brake consumption and occurrence of shock, and obtains smooth operation Can do.
[0023]
According to the configuration of the third aspect, since the combination section where both the position holding control and the mechanical brake work simultaneously is set, the transition from the mechanical brake action during acceleration to the position holding control and the position holding control during deceleration are performed. The transition to the mechanical brake action can be performed smoothly without shock.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
[0025]
In this embodiment, an excavator is taken as an application target.
[0026]
FIG. 1 shows a schematic configuration and device arrangement of the entire shovel, and FIG. 2 shows a block configuration of a drive / control system.
[0027]
In FIG. 1, 1 is a crawler type lower traveling body, 2 is an upper swing body, 3 is a drilling attachment mounted on the front part of the upper swing body 2, and this drilling attachment 3 includes a boom 4, an arm 5, and a bucket 6. A boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9.
[0028]
The lower traveling body 1 includes left and right crawlers 10L and 10R, and the both crawlers 10L and 10R are driven to rotate by traveling motors 11L and 11R and speed reducers 12L and 12R, respectively.
[0029]
The upper swing body 2 includes an engine 13, a hydraulic pump 14 and a generator 15 driven by the engine 13, a battery 16, a swing electric motor 17, and the speed reduction mechanism 18.
[0030]
As shown in FIG. 2, the oil discharged from the hydraulic pump 14 is supplied with control valves 19, 20, 21, 22, and 23 for the boom, arm, and bucket cylinders 7, 8, and 9 and the left and right traveling hydraulic motors 11L and 11R, respectively. The operation is controlled by the control valves 19-23.
[0031]
The generator 15 receives engine driving force via the speed increasing mechanism 24, and the electric power generated by the generator 15 is stored in the battery 16 via the controller 25 that controls the voltage and current, and the control means. It is added to the turning electric motor 17 through an inverter 26 which is a part of the motor.
[0032]
The turning electric motor 17 is provided with a mechanical brake 27 as a negative brake that generates a mechanical braking force. With the mechanical brake 27 released, the rotational force of the turning electric motor 17 passes through the turning reduction mechanism 18. Is transmitted to the upper swing body 2 and the swing body 2 turns left or right.
[0033]
Reference numeral 28 denotes a turning operation unit (for example, a potentiometer) as a turning operation unit. The operation unit 28 is operated by a lever 28a, and a command signal corresponding to the operation amount is input to a controller 29 which is a part of the control unit.
[0034]
Further, as a sensor, a speed sensor 30 for detecting the rotation speed (turning speed) of the turning electric motor 17 and a position sensor (for example, an encoder) 31 for detecting the turning stop position of the upper turning body 2 as 0 point are provided. Signals from both sensors 30 and 31 are input as control data to the controller 29 via the inverter 26.
[0035]
As shown in FIG. 3, the controller 29 has a predetermined width in the left and right turning directions (for example, 7 degrees each for the tilting angle of the operating lever 28a) to the absolute neutral point O where the operation amount of the turning operation unit 28 is zero. .5 °) is set, and when the lever is operated beyond the neutral range N, speed control based on the characteristics shown is performed, and as shown in FIG. The control mode is switched in accordance with the lever operation amount.
[0036]
That is, in the neutral range N, the mechanical brake section B in which the mechanical brake 27 exerts a braking action is set in an inner region including the absolute neutral point O, and position holding control (based on a signal from the position sensor 31). The position holding control section A in which the control for holding the revolving body 2 in place is performed is set in the outer region.
[0037]
Both sections B and A are set partially overlapping as shown in the figure, and the mechanical braking action and the position holding control action are simultaneously performed in the overlapping combined section C.
[0038]
In FIG. 4, LnL and LnR are neutral identification points in both the left and right turning directions that define the neutral range N, LbL and LbR are mechanical brake identification points that are the start and end points of the mechanical brake section B, and LzL and LzR are the start and end of position holding control. This is a position holding control identification point.
[0039]
The turning electric motor 17 is controlled by the controller 29 and the inverter 26 as follows based on such setting.
[0040]
At the time of turning acceleration When the lever operation amount is in the mechanical brake section B of FIG. 4, the mechanical brake 27 is operated, and the turning body 2 is held in a stopped state only by this mechanical braking force.
[0041]
Next, when the lever operation amount reaches the combined section C that is a boundary portion between the mechanical brake section B and the position holding control section A, the position holding control is activated, and the revolving body 2 is stopped by the mechanical brake force and the position holding control action. Retained.
[0042]
When the lever operation amount exceeds the combined use section C, the mechanical brake 27 is released and only the position holding control works, and the revolving structure 2 is held on the spot by the action of the position holding control.
[0043]
Further, when the lever operation amount exceeds the position holding control section A (neutral range N), the position holding control is also turned off, the turning electric motor 17 is rotated while being controlled based on the characteristics shown in FIG. Done.
[0044]
As described above, since the mechanical brake 27 operates in the stopped state, it is not necessary to always supply the current for holding in place to the turning electric motor 17 as in the case of stopping and holding in the position holding control, and energy is saved.
[0045]
In addition, since the position holding control works at the boundary with the speed control (position holding control section A), there is no shock due to the mechanical brake off at the time of turning acceleration as in the case of stopping and holding only with the mechanical brake 27, and smooth. Acceleration effect can be obtained.
[0046]
In addition, since the combined section C in which both the position holding control action and the mechanical brake 27 work simultaneously is set, the transition from the mechanical braking action during acceleration to the position holding control and the position holding control during deceleration described below are performed. The transition to the mechanical brake action can be performed smoothly without shock.
[0047]
At the time of turning deceleration When the operation lever 28a is returned from the turning command position outside the neutral range N to the neutral range N and enters the position holding control section A, the control for deceleration / stop is started.
[0048]
At this time, if the actual turning speed detected by the speed sensor 30 falls below the position holding control start speed set in advance in the controller 29, the position holding control becomes effective, and the motor 17 generates braking torque by the control. To do.
[0049]
Thus, since the position holding control is started in a sufficiently decelerated state, a large braking torque due to the position holding control is activated in a state where the deceleration is insufficient, and an excessive current flows to the turning electric motor 17, thereby causing the electric motor 17 and There is no risk of damaging the circuit.
[0050]
Next, the lever operation amount enters the mechanical brake section B, and
(A) The detected actual turning speed is less than or equal to a preset brake operating speed,
(B) When the condition that the state below the brake operating speed has continued for the set time is satisfied, the mechanical brake 27 is operated and the revolving structure 2 is stopped and held.
[0051]
In other words, even if the lever operation amount is in the mechanical brake section B, when the conditions (b) and (b) are not satisfied, the mechanical brake 27 is released as shown in the lower center of FIG. Only position hold control works.
[0052]
Thus, during turning deceleration, the mechanical brake 27 is not applied immediately even if the lever operation amount enters the mechanical brake section B, and the mechanical brake 27 is applied only when the state below the set speed (for example, speed 0) continues. Therefore, for example, when excavating at a certain point and scooping up earth and sand, turning and loading into a dump truck, turning, stopping, and turning continuously, the wear of the mechanical brake 27 and the occurrence of shock are prevented. Smooth operation can be obtained.
[0053]
By the way, in the above-described embodiment, an example is applied to a so-called parallel excavator that uses electricity as turning power and uses hydraulic pressure as power for other operations. However, the present invention applies electric power as a power source for all actuators. The present invention can also be applied to a so-called series excavator that uses power.
[0054]
Further, in the above-described embodiment, the configuration is such that “speed control” is performed according to the lever operation amount when the turning electric motor 17 is outside the neutral range N, but “speed control with torque limitation” is performed according to the lever operation amount. A configuration may be taken.
[0055]
Furthermore, the present invention is not limited to excavators, and can be widely applied to swivel work machines including cranes.
[0056]
【The invention's effect】
As described above, according to the present invention, since the mechanical brake works in the turning stop state, it is not necessary to always supply the current for holding in place to the electric motor as in the case of stopping and holding by the position holding control, thereby saving energy. In addition, since the mechanical brake is operated in the stopped state, it is not necessary to modify the mechanical brake for deceleration, and the existing one can be used as it is.
[0057]
In addition, because position hold control works at the boundary with speed control, there is no risk that the brakes will be consumed violently as in the case of deceleration / stop using only the mechanical brake, and the mechanical brake is turned on / off during turning acceleration / deceleration. Smooth acceleration / deceleration action can be obtained without any shock.
[0058]
In this case, when the swivel deceleration, when the rotation speed falls below the speed set in advance, i.e., since the position holding control while sufficiently decelerated starts, large braking torque by the position holding control in the deceleration insufficient state There is no risk of overcurrent flowing through the motor and causing damage to the motor or circuit.
[0059]
Further, according to the invention of claim 2 , there is, for example, that the mechanical brake is not immediately applied even when entering the mechanical brake section at the time of turning deceleration, and is applied when the state below the set speed (for example, speed 0) continues. At the time of excavating and scooping earth and sand, turning and loading into a dump truck, when turning → stopping → turning continuously and repeatedly, it prevents mechanical brake consumption and occurrence of shock, and obtains smooth operation Can do.
[0060]
According to the invention of claim 3, since the combined section where both the position holding control and the mechanical brake work simultaneously is set, the shift from the mechanical brake action during acceleration to the position holding control and the position holding control during deceleration are performed. The transition to the mechanical brake action can be performed smoothly without shock.
[Brief description of the drawings]
FIG. 1 is a side view showing an overall configuration and equipment arrangement of an excavator to which the present invention is applied.
FIG. 2 is a block configuration diagram of a drive / control system in the shovel.
FIG. 3 is a diagram showing a characteristic of lever operation amount / speed target value in the shovel.
4 is a diagram for explaining details of setting of a lever neutral range in the characteristics of FIG. 3; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2 Upper revolving body 17 Electric motor for turning 27 Mechanical brake 28 Turning operation part 28a Operation lever 26 Inverter which comprises control means 29 Same controller 30 Speed sensor 31 Position sensor for position holding control

Claims (3)

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, a turning speed detecting means for detecting a turning speed, and a mechanical brake A neutral range obtained by adding a width to an absolute neutral point where the operation amount of the operation means is 0, and in the neutral range, the control means includes a mechanical brake that generates force. A mechanical brake section is set on the absolute neutral side, and a position holding control section is set on the opposite side.
(I) operating the mechanical brake in the mechanical brake section in the neutral range;
(Ii) Stopping and holding the revolving body by performing position holding control in the position holding control section;
(Iii) performing speed control according to the operation amount of the operation means outside the neutral range;
(Iv) At the time of turning deceleration, the position holding control is started when the operation amount of the operating means is in the position holding control section and the turning speed is equal to or lower than a preset position holding control start speed. A turning control device for a work machine, characterized in that 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, a turning speed detecting means for detecting a turning speed, and a mechanical brake A neutral range obtained by adding a width to an absolute neutral point where the operation amount of the operation means is 0, and in the neutral range, the control means includes a mechanical brake that generates force. A mechanical brake section is set on the absolute neutral side, and a position holding control section is set on the opposite side.
Exercising the mechanical brake (a) mechanical brake section in the neutral range,
( B ) Stopping and holding the revolving body by performing position holding control in the position holding control section,
( C ) Perform speed control according to the operation amount of the operation means outside the neutral range ,
(D) At the time of turning deceleration, the position holding control is started when the operation amount of the operating means is in the position holding control section and the turning speed is equal to or lower than a preset position holding control start speed;
(E ) At the time of turning deceleration, the mechanical brake is operated when the operation amount of the operating means is in the mechanical brake section and the state where the turning speed is below the preset brake operating speed continues for the set time. A turning control device for a work machine, characterized in that it is configured. Combination section partially overlap each other in the position holding control section and the mechanical brake section is set in the neutral range, the control means that is configured so that worked both position hold control action and the mechanical brake in this combination section The turning control device for a work machine according to claim 1 or 2 , characterized in that:

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