JP2007146620A - Revolving type working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent natural revolving of a super structure by generating stop holding force replacing a hydraulic brake when revolving external force generating operation which is operation other than revolving operation, is performed to generate revolving external force to the super structure in a revolving stop state in a motor driving system. <P>SOLUTION: When traveling operation by traveling operation parts 27, 28 or excavating operation accompanied by arm pulling by an arm operating part 25 is performed in the revolving stop state, a controller 22 is constituted to output a torque command by 0-speed control only with a proportional term as a torque command for holding the super structure in the position, to a revolving motor 20. In this case, a mechanical brake 23 is released at the same time in traveling operation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a revolving work machine that revolves a revolving structure with an electric motor.

  An explanation will be given using an excavator as an example.

  As shown in FIG. 5, 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, and a work attachment 3 as a work device is mounted on the upper swing body 2. Composed.

  The work attachment 3 includes a boom 4 that can be raised and lowered, an arm 5 that is pivotally mounted around the horizontal axis at the tip of the boom 4, and a pivot that is pivotable around the horizontal axis at the tip of the arm 5. Consists of a bucket 6 and boom, arm, and bucket cylinders 7, 8, and 9 for operating them. Excavation operation with an arm pulling operation that pulls the arm 5 to the machine side, and an arm push that pushes the arm 5 to the opposite side. Performs dump operation with operation.

  In this shovel, generally, a hydraulic motor is used as a turning drive source, and a hydraulic drive system that controls the turning direction and the turning speed of the upper turning body 2 by changing the oil supply direction and the flow rate to the hydraulic motor. It has been.

  On the other hand, an electric motor drive system is known in which an electric motor is used as a turning drive source and the turning direction and speed of the upper turning body 2 are controlled by changing the rotation direction and speed of the electric motor (see Patent Document 1).

  In both of the hydraulic drive type and the electric motor drive type, a mechanical brake such as an electromagnetic brake is provided, and the upper revolving unit 2 is basically released by releasing the mechanical brake during the turning operation and operating during the non-turning operation. It is configured to be held in a stopped state.

  In this case, in the hydraulic drive system, the hydraulic brake is operated by a control valve provided in the hydraulic motor circuit, and the upper swing body 2 is held in a stopped state by the sum of the hydraulic brake force and the mechanical brake force.

  On the other hand, in the electric motor drive system, a configuration in which the upper swing body 2 is stopped and held by operating a mechanical brake without energizing the swing motor from the viewpoint of energy saving during a non-turn operation is performed (see Patent Document 2).

  Therefore, in the case of the electric motor drive system in which the hydraulic brake does not work, the force that holds the upper swing body 2 in the stopped state during the non-turn operation is only the mechanical brake force.

  However, a turning external force may be generated in the upper turning body 2 even during a non-turning operation.

  In particular, when a traveling operation, especially a spin turn or pivot turn operation, is performed, a large turning external force is generated in the upper swing body 2 due to inertia.

  In addition, during work operations, particularly during excavation operations that involve arm pulling operations (including excavation operations using only arm pulling operations), a lateral excavation reaction force acts on the work attachment 3 through the bucket, and this is the upper part of the turning external force. It may act on the swivel body 2.

  In this case, in the motor drive system, the upper swing body 2 is stopped and held only by the mechanical brake force as described above, and since the stop holding force is smaller than that of the hydraulic drive system, the turning external force is the stop holding force. Thus, there is a problem that the upper revolving unit 2 rotates and the operability and workability are deteriorated by natural turning unintended by the operator.

  Further, since the mechanical brake slips and occurs every time when the excavation operation is frequently performed, the service life of the brake is remarkably reduced. There was also a problem that the life design of the brake had to be increased.

  In the hydraulic drive system, since the external turning force generated at the time of excavation operation is relatively small, the brake is released from the viewpoint of mechanical brake protection, and the upper revolving body 2 is stopped and held by the hydraulic braking force. However, when the mechanical brake is released in the electric motor drive system in which the hydraulic brake does not work, the upper swing body 2 frequently turns and the workability deteriorates.

  In addition, in the configuration that activates the mechanical brake at the time of non-turning operation, it is conceivable to increase the stop holding capacity of the mechanical brake, but this increases the size of the brake, which is very disadvantageous in terms of space and cost, Not realistic.

  On the other hand, Patent Document 3 discloses a technique for performing electric motor control for holding the upper-part turning body in a stopped state when a turning external force is generated by excavation operation or the like while the turning is stopped.

In this known technique, speed feedback control is performed with the deviation between the target speed (0) and the actual speed so that the motor speed becomes zero by exerting a force against the external turning force, or position feedback that eliminates the position deviation. I am going to do control.
JP-A-11-93210 JP 2001-11897 A Japanese Patent Laid-Open No. 2004-112805

  The above-mentioned Patent Document 3 does not specify the specific content of the speed feedback control.

  However, the purpose is to generate a torque against the turning external force that is greater than the turning external force and stop the movement of the electric motor, and if the turning body moves due to a large turning external force, Returning to the original position by the motor torque when the external force disappears, that is, holding the turning electric motor at the position (on the spot) at the start of control is clearly shown.

  Therefore, in the known technique described in Patent Document 3, it is considered that PI control including an integral term for eliminating a steady-state deviation is performed.

  However, according to the position feedback control and the PI control, as described above, a torque is generated to return to the original when the turning external force is lost, and this torque causes “swing back” in which the upper turning body moves in the reverse direction. .

  Since this “shakeback” occurs regardless of the operation and intention of the operator, the operability is deteriorated for the operator, and it is dangerous for workers around the machine.

  Therefore, in the motor drive system, when a turning external force generation operation is performed in a turning stop state, the present invention generates a stop holding force in place of the hydraulic brake to suppress the natural turning of the upper turning body and eliminates the external force. It is an object of the present invention to provide a swivel work machine that can prevent the upper swing body from swinging back and forth.

  According to the first aspect of the present invention, there is provided a lower traveling body, an upper swing body that is pivotably mounted on the lower traveling body, a working device attached to the upper swing body, and a swing motor that swings and drives the upper swing body. Each of the running, working, and turning operations for performing the running operation for instructing the running operation of the lower traveling body, the turning operation for instructing the turning operation of the upper turning body, and the work operation for instructing the operation of the work device. Detecting means for detecting a turning external force generating operation in which a turning external force is generated in the upper turning body in an operation other than the turning operation in a swing type work machine having a means and a mechanical brake for holding the upper turning body in a stopped state And a control means for controlling the operation of the swing motor and the mechanical brake, and the control means is provided for the swing motor when the swing external force generation operation is performed in the swing stop state. , As the holding torque command to hold the upper rotating body in that position, but that is configured to output a torque command by 0 Speed control of only the proportional term.

  According to a second aspect of the present invention, in the configuration of the first aspect, when the turning external force generation operation is performed in a turning stop state, the mechanical brake is brought into a brake release state and a holding torque command for the turning electric motor is output. It is composed of.

  According to a third aspect of the present invention, in the configuration of the first or second aspect, the detecting means is configured to detect a traveling operation as a turning external force generating operation.

  According to a fourth aspect of the present invention, in the configuration of the first or second aspect, the detecting means is configured to detect a traveling turn operation as a turning external force generating operation.

  According to a fifth aspect of the present invention, in the configuration of the first or second aspect, the detecting means is configured to detect a work operation as a turning external force generating operation.

  According to a sixth aspect of the present invention, in the configuration of the fifth aspect, an arm is attached to the tip of the boom that can be raised and lowered, and a bucket is rotatably attached to the tip of the arm to constitute a work attachment as a work device, and detecting means Is configured to detect the arm pulling operation of the work attachment as a turning external force generating operation.

  According to the present invention, a turning external force generation operation (traveling operation in claim 3, traveling turn operation in claim 4, work operation in claims 5 and 6) is detected, and this turning external force generation operation is performed in a turning stop state. In this case, since the holding torque is generated in the swing electric motor by the control means, the upper swing body can be held in the stopped state while protecting the mechanical brake during the operation of generating the swing external force.

  In this case, a brake combined system that generates a holding torque while the mechanical brake is operated may be employed, or a brake releasing system that releases the mechanical brake and performs a stop holding action only by the holding torque as in the invention of claim 2 may be adopted. It may be taken.

  According to the brake combined use system, a sufficient stop holding force can be exhibited even during an operation that generates a large turning external force, such as a traveling turn operation, while reducing the mechanical brake load.

  On the other hand, according to the brake release method, the mechanical brake load can be further reduced and the life of the brake can be improved.

  Further, according to the present invention, the above control is performed only during an operation in which a turning external force is generated, and the electric motor is kept in a non-energized state during other operations, so that an energy saving effect can be maintained. In particular, in the inventions of claims 3 to 6, the above control is performed only at the time of a traveling operation and an excavation operation in which a turning external force is likely to be generated.

  By the way, when controlling an electric motor by a speed feedback loop, PI (proportional integration) control including an integral term for eliminating a steady-state deviation as described in Patent Document 3 is usually employed.

  According to this PI control, when speed 0 is the target, the motor torque command is as follows.

Motor torque command = Kp × (0−motor speed (detection value)) + KiΣ (0−motor speed)
Kp is a proportional constant, Ki is an integral constant, and Σ is a past deviation accumulation.

  In this PI control, as shown in FIG. 4, when an external force torque is applied, an electric motor torque higher than that is generated to stop the movement of the electric motor, so that a state without a speed deviation (zero speed state) can be realized. There are benefits.

This is because the value of Σ (0-motor speed) is increased by being moved by the external force first. In the state where there is an external force and there is no speed deviation,
External torque = Ki x Σ (0-motor speed)
The relationship is established.

  However, even if there is no external force from here, the motor torque remains as shown by the circled portion in FIG. 4 due to the above Ki × (0−motor speed), and the motor accelerates in the reverse direction due to this remaining torque. . This movement continues until Σ (0-motor speed) becomes 0 by the motor moving in the opposite direction.

  That is, for example, in the excavator of FIG. 5, when the external force is lost, the “swing back” movement of the upper swing body 2 occurs.

  In this case, since there is a turning speed reduction mechanism (gear mechanism) between the electric motor and the upper swing body 2 and the speed ratio between the two is large, the “swing back” of the upper swing body 2 is actually slight. However, since this movement occurs regardless of the operator's operation and intention, not only is it not preferable in terms of operability, but when the operator around the machine approaches at the same time as the machine stops, 6 is in danger.

  On the other hand, according to the present invention, since the zero speed control of only the proportional term is performed instead of the PI control, the above problem can be solved.

That is, according to the zero speed control of only the proportional term,
Electric motor torque command = Kp × (0−motor speed (detected value)... (1)
When an external force is applied, a motor torque that balances with the external force is generated as shown in FIG. 3, but this does not stop the movement of the motor, and the external force disappears and at the same time the motor torque disappears (PI control). No torque remaining in the case of

  Therefore, the electric motor continues to rotate little by little while the external force is applied, and stops at the position at that time when the external force disappears. That is, the “swing back” of the upper swing body that is not intended by the operator as in the case of PI control does not occur.

  The turning angle until the vehicle stops is extremely small because the speed ratio is large as described above, and there is no practical problem.

  Thereby, it is possible to perform control with an emphasis on operability and safety.

  In the embodiment, an excavator is taken as an application target.

  FIG. 1 shows a block configuration of a drive system and a control system of an excavator according to the embodiment. This will be described with reference to FIG.

  A hydraulic pump 11 is driven by the engine 10, and the discharge oil is supplied to the left and right traveling motors 12, 13 that drive the boom, arm, and bucket cylinders 7 to 9 and the lower traveling body 1. But is shown here as a single valve block).

  In addition, a generator 16 is connected to the engine 10 via a speed increasing mechanism 15, and electric power generated by the generator 16 is stored in a battery 18 via a controller 17 that controls voltage and current. Then, it is added to the swing motor 20 via the inverter 19.

  As a result, the turning electric motor 20 rotates, and the rotational force is transmitted to the upper turning body 2 via the turning speed reduction mechanism 21 so that the turning body 2 turns left or right.

  The turning electric motor 20 is controlled by an inverter at the time of turning acceleration and performs an electric motor action with at least one of the electric power of the generator 16 and the battery 18, and is controlled by an inverter at the time of deceleration to perform an electric generator action. 18 is stored.

  The output shaft 20a of the turning electric motor 20 is provided with a mechanical brake (here, an electromagnetic brake is exemplified) 23 that operates based on a brake / release command from a controller 22 as a control means.

  The mechanical brake 23 generates a mechanical braking force in the swing electric motor 20 during operation and keeps the upper swing body 2 in a stopped state.

  On the other hand, as operation means, boom-type, arm, bucket cylinders 7 to 9 and left and right traveling motors 12 and 13 and lever-type operation units (operation means) 24 to 29 are provided for each actuator of the turning electric motor 20. . Hereinafter, these are referred to as a boom operation unit, an arm operation unit, a bucket operation unit, a left travel operation unit, a right travel operation unit, and a turning operation unit as necessary.

  Operation signals (including non-operation signals) from the operation units 24 to 29 are sent to the controller 22, and the respective operation directions and operation amounts from the controller 22 to the control valve 14 based on operation signals other than the turning operation signal. An operation command signal corresponding to is output. As a result, the boom, arm, and bucket cylinders 7 to 9 and the left and right traveling motors 12 and 13 are controlled in accordance with the operation.

  On the other hand, a command is issued from the controller 22 to the inverter 19 based on the turning operation signal, and acceleration / deceleration control of the turning electric motor 20 is performed based on this command.

  In addition, an encoder 30 is provided as means for detecting the speed (rotational position) of the turning electric motor 20, and a speed signal from the encoder 30 is sent to the controller 22 together with other operation signals.

Based on the above signals, the controller 22
a) No turning operation
b) On the condition that there is at least one of an arm pulling operation and a traveling operation, that is, a turning external force generation operation, zero speed control is performed to hold the turning motor 20 (upper turning body 2) in that position.

  This will be described with reference to the flowchart of FIG.

  At the start of control, it is determined whether or not there is a turning operation in step S1. If NO (operation is present), the mechanical brake 23 is released in step S2, and the control of the turning motor 20 according to the turning operation is performed in step S3. The normal turning control is performed (step S4).

  If YES in step S1 (no turning operation), it is determined in step S5 whether or not there is an arm pulling operation (excavation operation). If not, it is further determined in step S6 whether or not there is a traveling operation. .

  If there is no traveling operation, the process proceeds to step S7. After all, since there is no operation, the mechanical brake 23 is activated (step S7), and the motor control is stopped (step S8).

  On the other hand, if NO (with arm pulling operation) in step S5, the mechanical brake 23 is released in step S9, and if NO (with running operation) in step S6, the process proceeds directly to step S10, and the turning motor 20 controls (zero speed control with only proportional term) are started.

  In this case, the motor speed detected by the encoder 30 is read (step S11), the torque based on the equation (1) is calculated in step S12, and the torque command is output to the swing motor 20 (inverter 19). Is done.

  As described above, when there is a turning external force generation operation in which a turning external force is generated on the upper swing body 2, that is, an operation other than a turning operation, that is, an excavation operation accompanied by an arm pulling and a traveling operation in a turning stop state. In addition, since the swing motor 20 is configured to generate a torque for holding the upper swing body 2 in place, the upper swing body 2 is held in a stopped state while protecting the mechanical brake 23 during a swing external force generation operation. be able to.

  In this case, the mechanical brake 23 is released during the arm pulling operation in many cases when the operator assumes that the turning external force generated is smaller than that during the traveling operation and that the turning external force is generated. Based on that.

  By adopting this brake release method, it is possible to eliminate the burden on the mechanical brake 23 while ensuring the stop holding force necessary for the arm pulling operation.

  On the other hand, the reason why the mechanical brake 23 is not released at the time of the traveling operation is based on the fact that the generated turning external force is large and that the turning is often unexpected by the operator.

  By adopting this brake combined system, the upper swing body 2 can be reliably stopped and held while reducing the load on the mechanical brake 23.

  In addition, the holding control of the turning electric motor 20 is not performed at all during the non-turning operation, but only during the operation in which the turning external force is generated. In other operations, the turning electric motor 20 is kept in a non-energized state. Energy saving effect can be maintained.

  Moreover, as the motor control, the zero speed control with only the proportional term, that is, the PI control where the force for returning the swing motor 20 to the original position when the external force is lost as described above is applied, but the place where the motor moves Therefore, the “swing back” of the upper swing body that occurs in the case of PI control can be prevented. Thereby, operativity and safety can be improved.

  By the way, in the said embodiment, although it was set as the structure which performs holding | maintenance control of the turning electric motor 20 irrespective of the content at the time of driving | running | working operation, since it is at the time of turn operation, such as a spin turn and a pivot turn, it is easy to generate | occur | produce a big turning external force. From the viewpoint of enhancing the effect, the holding control may be performed only during the turn operation in the traveling operation.

  In this case, the spin turn can be detected by a traveling operation in the opposite direction to the left and right, and the pivot turn can be detected by an operation of stopping on the left and right sides and traveling on the opposite side.

  On the other hand, in the above embodiment, the mechanical brake 23 is released during the arm pulling operation and the brake 23 is not released during the traveling operation. However, the mechanical brake 23 may be released during both operations. A configuration may be employed in which the mechanical brake 23 is not released during both operations.

  Further, the turning external force is not limited to the time of traveling and excavation, and may occur, for example, during a work operation involving pushing of the arm, but may not occur during the excavation operation involving arm pulling operation.

  Therefore, while the operation operation and the traveling operation are all regarded as a turning external force generation operation, this turning external force generation operation is a work operation, excavation operation with arm pulling, other work operation, turn operation, other travel operation, etc. The operator may arbitrarily select a work item for which holding control is performed using a selection switch.

It is a block block diagram of the drive system and control system of the shovel concerning the embodiment of the present invention. It is a flowchart for demonstrating the effect | action of embodiment. It is a figure which shows the relationship of the external force torque by the 0 speed control of only a proportional term, an electric motor torque, and an electric motor speed. It is a figure which shows the relationship between the external force torque by PI control, an electric motor torque, and an electric motor speed. It is a side view of an excavator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower traveling body 2 Upper revolving body 3 Work attachment (working device)
DESCRIPTION OF SYMBOLS 4 Boom 5 Arm 6 Bucket 20 Turning electric motor 22 Controller which serves both as control means and detection means 25 Arm operation part which serves as arm operation means and detection means 27, 28 Left and right travel operation parts which serve as travel operation means and detection means 29 Swing operation means And a turning operation unit that also serves as a detecting means 30 Encoder for detecting the speed of the turning motor

Claims (6)

  A lower traveling body, an upper swinging body that is pivotably mounted on the lower traveling body, a working device attached to the upper swinging body, a swing motor that swings and drives the upper swinging body, and the lower traveling body A traveling operation for instructing a traveling operation, a turning operation for instructing a turning operation of the upper revolving body, and a running operation, a work, a turning operation means for performing a work operation for instructing an operation of the working device, and an upper revolving body are provided. In a swing type work machine having a mechanical brake for holding in a stopped state, a detection means for detecting a swing external force generating operation that is an operation other than a swing operation and generates a swing external force on the upper swing body, the swing motor and the mechanical And a control means for controlling the operation of the brake. The control means moves the upper swing body against the swing motor when the swing external force generation operation is performed in the swing stop state. As the holding torque command held in position, slewing type working machine, characterized in that it is configured to output a torque command by 0 Speed control of only the proportional term.   The control means is configured to set the mechanical brake to a brake released state and to output a holding torque command for the turning electric motor when a turning external force generation operation is performed in the turning stopped state. The turning work machine according to 1.   3. The turning work machine according to claim 1, wherein the detecting means is configured to detect a traveling operation as a turning external force generating operation.   3. The turning work machine according to claim 1, wherein the detecting means is configured to detect a traveling turn operation as a turning external force generating operation.   The swing type work machine according to claim 1 or 2, wherein the detecting means is configured to detect a work operation as a turn external force generating operation.   An arm is attached to the tip of the boom that can be raised and lowered, and a bucket is rotatably attached to the tip of the arm to constitute a work attachment as a work device, and the detecting means uses the arm pulling operation of the work attachment as a turning external force generating operation. 6. A swing work machine according to claim 5, wherein the swing work machine is configured to detect.

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