JP2004036304A - Turning control device for working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely hold a turning body in a stopping state, to smoothly perform the turning deceleration/stopping and acceleration action, to prevent an energy loss for stopping and holding; and to use an existing mechanical brake as it is. <P>SOLUTION: A section for stopping-holding the turning body only by the mechanical brake 27, a section for holding the turning body only by position holding control and a section for simultaneously operating both are set in a neutral range of a preset operation lever 28a. At turning deceleration time, when a turning speed becomes a preset position holding control starting speed or less, the position holding control is started, and when a state of being not more than a brake operating speed continues for a specific time, the mechanical brake 27 is operated. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turning control device for a working machine such as a shovel or a crane which drives a turning body by an electric motor.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a swing-type work machine such as a shovel or a crane usually employs a hydraulic motor as a swing drive source and a hydraulic motor drive system in which the hydraulic motor is driven by oil discharged from a hydraulic pump.
[0003]
When using this hydraulic motor drive system, a control valve is provided between the hydraulic pump and the hydraulic motor, and the control valve controls the direction, pressure, and flow rate to control the operating direction, force, and speed of the hydraulic motor. .
[0004]
However, this method has a problem that a large amount of hydraulic energy is squeezed out by the control valve and energy loss is large.
[0005]
Therefore, recently, a motor drive system using an electric motor as a turning drive source has been proposed (for example, see Japanese Patent Application Laid-Open No. H11-93210).
[0006]
Further, in a large-sized electric shovel for climbing cranes and mining, an electric motor drive system has been conventionally used for the turning operation.
[0007]
In these electric motor turning drive systems, the turning direction and the turning speed are controlled by changing the rotating direction and the speed of the electric motor, so that the energy efficiency can be greatly improved.
[0008]
On the other hand, when this motor turning drive system is adopted, a feedback speed control system for controlling the speed in a direction to eliminate the deviation between the target speed and the actual speed corresponding to the lever operation amount is usually used.
[0009]
[Problems to be solved by the invention]
When this speed control method is adopted, the revolving structure stops by the braking torque acting when the command speed is 0 when the lever is neutral and the commanded speed is 0. Since the stop holding force) is not output, a reliable stop holding function cannot be obtained.
[0010]
Therefore, it is conceivable to use position holding control (servo lock control = control for holding the revolving superstructure 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 a large amount of energy is lost because a current for holding the revolving structure in a stopped state must always flow through the electric motor.
[0012]
On the other hand, as another stop holding method, it is conceivable to employ a mechanical brake mounted on a hydraulically driven working machine.
[0013]
However, mechanical brakes originally have a structure that operates as a parking brake in a revolving-body stopped state, and if this is used as it is as a means for decelerating / stopping the electric motor in the electric motor-driven turning system, the brake will be heavily worn and However, there is a problem in that the motion of the revolving body during deceleration / acceleration is jerky due to the brake on / off shock, and a smooth turning stop / acceleration action cannot be obtained.
[0014]
Although it is possible to modify the mechanical brake for deceleration and stop holding, it is not advisable to increase the cost.
[0015]
Therefore, the present invention solves such a problem, and can surely hold the revolving body in a stopped state, and can smoothly perform the deceleration / stopping and acceleration operations of the revolving body, and further, energy loss for holding the stop is reduced. An object of the present invention is to provide a turning control device for a working machine that can use the existing mechanical brake without any change.
[0016]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided an electric motor for driving the revolving body to rotate, operating means for issuing a turning command, control means for controlling the electric motor based on the turning command from the operating means, and a turning speed for detecting a turning speed. A detecting means, and a mechanical brake for generating a mechanical braking force, wherein the control means previously sets a neutral range obtained by adding a width to an absolute neutral point where the operation amount of the operating means is 0, and 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, and the control means operates the mechanical brake in the mechanical brake section in the neutral range to perform the position holding control. The revolving structure is stopped and held by performing the position holding control in the section, and the speed control according to the operation amount of the operation means outside the neutral range. Those that are configured to perform.
[0017]
According to a second aspect of the present invention, in the configuration of the first 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 controls the mechanical brake and the position holding in the combined section. It is configured to exercise both control actions.
[0018]
According to a third aspect of the present invention, in the configuration of the first or second aspect, the control means is configured such that, when turning is decelerated, the operation amount of the operating means is in the position holding control section, and the turning speed is a preset position holding control start speed The position holding control is started when the following conditions are satisfied.
[0019]
According to a fourth aspect of the present invention, in the configuration according to any one of the first to third aspects, when the turning is decelerated, the control means operates the operating means in the mechanical brake section and sets the turning speed to a predetermined value. The mechanical brake is configured to operate when the speed becomes equal to or less than the speed for a set time.
[0020]
According to the above configuration, since the mechanical brake operates in the turning stop state, it is not necessary to constantly supply a current for holding the spot to the electric motor as in the case where the stop is held by the position holding control, thereby saving energy. In addition, since the mechanical brake is operated in the stopped state, there is no need to modify the mechanical brake for deceleration, and the existing brake can be used as it is.
[0021]
In addition, since the position holding control works at the boundary with the speed control, unlike the case of decelerating / stopping only with the mechanical brake, there is no danger that the brake will be exhausted severely, and the mechanical brake is turned on / off during turning acceleration / deceleration. No acceleration shock and smooth acceleration / deceleration can be obtained.
[0022]
According to the second aspect of the present invention, since the combined section in which both the position holding control and the mechanical brake work simultaneously is set, the shift from the mechanical braking operation to the position holding control during acceleration and the position holding during deceleration are performed. The transition from the control to the mechanical braking operation can be smoothly performed without a shock.
[0023]
According to the third aspect of the present invention, the position holding control is started when the turning speed becomes equal to or lower than the preset speed during the turning deceleration, that is, in a sufficiently decelerated state. As a result, there is no danger that an excessive current will flow through the motor due to the large braking torque, thereby damaging the motor and the circuit.
[0024]
According to the configuration of the fourth aspect, at the time of turning deceleration, the mechanical brake is not actuated immediately after entering the mechanical brake section, but is actuated when the state at or below the set speed (for example, speed 0) is continued. Exercise the mechanical brakes and prevent the occurrence of shocks when turning, stopping, and turning repeatedly, such as when excavating at the site to scoop the earth and sand, turning and loading the dump truck, and obtain smooth operation. Can be.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
[0026]
In this embodiment, a shovel is taken as an example to be applied.
[0027]
FIG. 1 shows a schematic configuration and equipment arrangement of the entire shovel, and FIG. 2 shows a block configuration of a drive / control system.
[0028]
In FIG. 1, reference numeral 1 denotes a crawler-type lower traveling body, 2 denotes an upper revolving superstructure, and 3 denotes an excavation attachment attached to a front portion of the upper revolving superstructure 2. The excavation 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.
[0029]
The lower traveling body 1 includes left and right crawlers 10L and 10R, and the both crawlers 10L and 10R travel while being rotationally driven by traveling motors 11L and 11R and reduction gears 12L and 12R, respectively.
[0030]
The upper swing body 2 is equipped with an engine 13, a hydraulic pump 14 and a generator 15 driven by the engine 13, a battery 16, a turning motor 17 and a speed reduction mechanism 18.
[0031]
As shown in FIG. 2, the discharge oil of the hydraulic pump 14 is provided with control valves 19, 20, 21, 22, and 23 for the cylinders 7, 8, 9 of the boom, arm, and bucket and the left and right traveling hydraulic motors 11L, 11R, respectively. The operation is controlled by the control valves 19 to 23.
[0032]
The generator 15 is supplied with an engine driving force via a speed increasing mechanism 24. The electric power generated by the generator 15 is stored in a battery 16 via a controller 25 for controlling voltage and current. Is added to the turning electric motor 17 via an inverter 26 which is a part of the motor.
[0033]
The turning electric motor 17 is provided with a mechanical brake 27 as a negative brake for generating a mechanical braking force. When the mechanical brake 27 is released, the turning force of the turning electric motor 17 passes through the turning deceleration mechanism 18. And the upper revolving unit 2 is turned to the left or right.
[0034]
Reference numeral 28 denotes a turning operation unit (for example, a potentiometer) as turning operation means. 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 means.
[0035]
Further, as sensors, a speed sensor 30 for detecting the rotation speed (swing 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 to the controller 29 via the inverter 26 as control data.
[0036]
As shown in FIG. 3, the controller 29 previously has a predetermined width in the left and right turning directions (for example, each of the right and left 7 degrees depending on the tilt angle of the operation lever 28a) as shown in FIG. .5 °) is set, and when the lever is operated beyond the neutral range N, the speed control based on the illustrated characteristics is performed, and as shown in FIG. , The control mode is switched according to the lever operation amount.
[0037]
That is, within the neutral range N, the mechanical brake section B in which the mechanical brake 27 exerts the braking action is set in the inner area including the absolute neutral point O, and the position holding control (based on the signal from the position sensor 31). The position holding control section A in which the revolving structure 2 is controlled to hold the revolving superstructure 2 in place is set in the outer region.
[0038]
The sections B and A are partially overlapped as shown in the figure, and the mechanical braking action and the position holding control action are simultaneously performed in the overlapped combined section C.
[0039]
In FIG. 4, LnL and LnR are neutral identification points that define the neutral range N in the left and right turning directions, 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 the position holding control. This is a position holding control identification point which is a point.
[0040]
The turning electric motor 17 is controlled as follows by the controller 29 and the inverter 26 based on such settings.
[0041]
When the lever operation amount at the time of turning acceleration is in the mechanical brake section B in FIG. 4, the mechanical brake 27 is operated, and the revolving unit 2 is held in a stopped state only by the mechanical brake force.
[0042]
Next, when the lever operation amount reaches the combined section C which is a boundary between the mechanical brake section B and the position holding control section A, the position holding control is activated, and the revolving unit 2 is stopped by the mechanical braking force and the position holding control action. Will be retained.
[0043]
When the lever operation amount exceeds the combined section C, the mechanical brake 27 is released, and only the position holding control operates, and the revolving superstructure 2 is held in place by the operation of the position holding control.
[0044]
Further, when the lever operation amount exceeds the position holding control section A (the neutral range N), the position holding control is also turned off, and the turning electric motor 17 rotates while being speed-controlled based on the characteristics shown in FIG. Done.
[0045]
As described above, since the mechanical brake 27 operates in the stop state, it is not necessary to constantly supply the current for holding the place to the turning motor 17 as in the case of stopping and holding by the position holding control, thereby saving energy.
[0046]
In addition, since the position holding control is performed at the boundary with the speed control (position holding control section A), there is no shock due to the mechanical brake being turned off during the turning acceleration, as in the case of stopping and holding only with the mechanical brake 27, and smooth. A high acceleration effect can be obtained.
[0047]
Further, since the combined section C in which both the position holding control action and the mechanical brake 27 are simultaneously operated 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 operation can be performed smoothly without shock.
[0048]
When the turning deceleration 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.
[0049]
At this time, when the actual turning speed detected by the speed sensor 30 falls below the position holding control start speed set in the controller 29 in advance, the position holding control becomes effective, and the electric motor 17 generates a braking torque by the same control. I do.
[0050]
As described above, since the position holding control is started in a sufficiently decelerated state, a large braking torque by the position holding control works in a state of insufficient deceleration, and an excessive current flows through the turning electric motor 17. There is no risk of damaging the circuit.
[0051]
Next, the lever operation amount enters the mechanical brake section B, and
(1) The detected actual turning speed is equal to or lower than a preset brake operating speed;
{Circle around (2)} When the condition that the state below the brake operation speed has continued for the set time is satisfied, the mechanical brake 27 operates and the revolving superstructure 2 is stopped and held.
[0052]
Conversely, even if the lever operation amount is in the mechanical brake section B, if the above conditions (1) and (2) are not satisfied, the mechanical brake 27 is released as shown in the center of the lower column in FIG. Only the position holding control works.
[0053]
In this way, at the time of turning deceleration, the mechanical brake 27 is not actuated immediately even if the lever operation amount enters the mechanical brake section B, and the mechanical brake 27 is actuated for the first time when the state below the set speed (for example, the speed 0) is continued. For example, when excavating at a certain point to scoop the earth and sand, and turning and stopping → turning continuously as in turning and loading into a dump truck, wear of the mechanical brake 27 and occurrence of a shock are prevented, A smooth operation can be obtained.
[0054]
By the way, in the above-described embodiment, the so-called parallel type shovel using electric power as the turning power and hydraulic pressure as the power for other operations is taken as an example, but the present invention is applied to electric power as a power source for all actuators. The present invention can also be applied to a so-called series type shovel using power.
[0055]
In the above-described embodiment, the speed of the turning electric motor 17 is set to “speed control” outside the neutral range N according to the lever operation amount. However, “speed control with torque limitation” is performed according to the lever operation amount. A configuration may be adopted.
[0056]
Further, the present invention is not limited to a shovel, and can be widely applied to a swing-type working machine including a crane.
[0057]
【The invention's effect】
As described above, according to the present invention, since the mechanical brake operates in the turning stop state, it is not necessary to constantly supply a current for holding the place to the electric motor as in the case of stopping and holding by the position holding control, thereby saving energy.
[0058]
In addition, since the mechanical brake is operated in the stopped state, there is no need to modify the mechanical brake for deceleration, and the existing brake can be used as it is.
[0059]
In addition, since the position holding control works at the boundary with the speed control, unlike the case of decelerating / stopping only with the mechanical brake, there is no danger that the brake will be exhausted severely, and the mechanical brake is turned on / off during turning acceleration / deceleration. No acceleration shock and smooth acceleration / deceleration can be obtained.
[0060]
According to the second aspect of the present invention, since the combined section in which both the position holding control and the mechanical brake work simultaneously is set, the shift from the mechanical braking operation to the position holding control during acceleration and the position holding during deceleration are performed. The transition from the control to the mechanical braking operation can be smoothly performed without a shock.
[0061]
According to the third aspect of the present invention, the position holding control is started at the time of turning deceleration when the turning speed becomes equal to or less than a preset speed, that is, the position holding control is started in a sufficiently decelerated state. Therefore, there is no possibility that an excessive current flows through the turning electric motor due to the large braking torque caused by the above and the electric motor and the circuit may be damaged.
[0062]
According to the invention of claim 4, the mechanical brake is not actuated immediately after entering the mechanical brake section at the time of turning deceleration, but is actuated when the state below the set speed is continued. It is possible to prevent wear and shock from occurring, and to obtain a smooth operation.
[Brief description of the drawings]
FIG. 1 is a side view showing the overall configuration and equipment arrangement of a shovel 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 a lever operation amount / speed target value in the shovel.
FIG. 4 is a diagram for explaining details of setting of a lever neutral range in the characteristic of FIG. 3;
[Explanation of symbols]
2 Upper revolving unit 17 Revolving motor 27 Mechanical brake 28 Revolving operation unit 28a Operating lever 26 Inverter 29 constituting control means Controller 30 Speed sensor 31 Position sensor for position holding control

Claims (4)

An electric motor for driving the revolving body to rotate, operating means for issuing a turning command, control means for controlling the electric motor based on the turning command from the operating means, turning speed detecting means for detecting a turning speed, and mechanical brake A mechanical brake for generating a force, wherein the control means is set in advance with a neutral range obtained by adding a width to an absolute neutral point where the operation amount of the operating means is 0, and in the 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, and the control means operates the mechanical brake in the mechanical brake section in the neutral range and performs position holding control in the position holding control section. In this way, the revolving superstructure is stopped and held, and speed control is performed outside the neutral range according to the operation amount of the operation means. Working machine turn control system, characterized in that the. 2. The turning control device for a work machine according to claim 1, wherein a combined section in which a part of the mechanical brake section and a part of the position holding control section in the neutral range overlap is set, and the control means controls the mechanical brake and the position holding control in the combined section. A turning control device for a work machine, wherein the turning control device is configured to perform both functions. 3. The turning control device for a work machine according to claim 1, wherein the control unit is configured such that, when the turning is decelerated, the operation amount of the operating unit is in the position holding control section, and the turning speed is equal to or less than a preset position holding control start speed. A turning control device for a working machine, wherein the turning control device is configured to start the position holding control when the rotation of the work machine is stopped. The turning control device for a work machine according to any one of claims 1 to 3, wherein the control means is configured such that, when the turning is decelerated, the operation amount of the operating means is in a mechanical brake section, and the turning speed is set to a predetermined value. A turning control device for a working machine, wherein a mechanical brake is actuated when a state in which the speed becomes equal to or less than a speed continues for a set time.

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