JP2008231903A - Revolving controller and working machine equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a revolving controller of a working machine capable of preventing a revolving superstructure from moving reversely while suppressing discontinuous fluctuation of torque and to provide the working machine equipped with it. <P>SOLUTION: This working machine is equipped with the revolving controller 26 capable of setting first target torque t1 for driving an electric motor 18 for revolving at target speed v0 set in accordance with amount of operation a0 of an operation lever and second target torque t2 for holding a super structure 3 in the place based on actual speed detected by a speed sensor 27 and operating the electric motor 18 for revolving in accordance with the torque being the torque in the same direction as that of the first target torque t1 and having a larger absolute value among the first target torque t1 and the second target torque t2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  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.

  Conventionally, in a swivel work machine such as an excavator or a crane, a hydraulic motor driven by oil discharged from a hydraulic pump has been used as a swivel drive source of the swivel body.

  On the other hand, in recent years, a technique for turning a turning body with an electric motor is known (for example, Patent Document 1).

  Thus, in the technique of turning the revolving body with the electric motor, the target speed is set according to the operation amount of the turning operation lever, and the speed control (determining the torque command using the deviation between the target speed and the actual turning speed ( So-called speed feedback control) is performed.

  In the speed feedback control, in order to improve the followability to the speed, for example, in the case of PID control, the gain is increased as much as possible. However, when the gain is increased, even if the deviation between the target speed and the actual turning speed is small, the command torque to the motor becomes too large with a slight lever operation. In some cases, it may be difficult to adjust the pressing force. Further, when a sudden lever operation is performed, the command torque to the motor may suddenly increase to cause a shock.

  On the contrary, in order to facilitate adjustment of the command torque to the motor by lever operation, for example, in the case of PID control, the gain is reduced or the integral gain is set to zero. However, if the gain is reduced, the command torque to the motor will be too small when working on slopes (under the weight of the work machine itself), etc. There may be a problem that the torque cannot be secured.

  As techniques for solving the problem of the speed feedback control, those described in Patent Documents 2 to 5 are known. In these Patent Documents 2 to 5, the two control systems are appropriately switched.

  Specifically, Patent Document 2 discloses a technique in which speed feedback control and torque control are switched with a specific operation amount of the operation lever as a boundary. Patent Document 3 discloses a technique in which speed control and position control are switched with a speed threshold of a target speed corresponding to the operation amount of the operation lever as a boundary. Patent Document 4 discloses a technique in which a normal speed control and a speed control with a proportional gain lower than the speed control are switched at a predetermined speed of the revolving structure.

Patent Document 5 discloses a technique for performing position holding control when the lever operation amount of the operation lever is in a preset neutral range, and performing torque control when the lever operation amount exceeds the neutral range. ing. Specifically, in the technique of Patent Document 5, the in-situ holding torque specified in the position holding control performed within the neutral range is stored in the controller, and when the neutral range is exceeded, the stored that Of the acceleration torque corresponding to the field holding torque and the lever operation amount, the turning body is driven to turn by the larger torque.
Japanese Patent Laid-Open No. 2001-10783 JP 2003-328398 A International Publication No. 2005/111322 Pamphlet JP 2005-273262 A JP 2004-36303 A

  However, when switching between two control systems as in Patent Documents 2 to 5, the torque fluctuates discontinuously (abruptly) at the switching point of the control system in order to interpolate the gap between these control systems. ) And smooth and stable control could not be performed.

  Further, in the technique of Patent Document 5, in the state after the lever operation amount exceeds the neutral range, the turning drive is performed by the larger torque of the in-situ holding torque and the acceleration torque. The in-situ holding torque is a torque required in the past that has occurred in the position holding control executed in the neutral range, and does not reflect the current working state. When the torque control is executed rather than when the torque for holding the swivel body on the spot is larger (for example, work on a sloping ground), the swivel moves backward against the operator's intention. There is a risk of it.

  The present invention has been made in view of the above problems, and provides a turning control device for a working machine and a working machine equipped with the turning control device that can prevent the reversal of the turning body while suppressing discontinuous fluctuations in torque. It is intended to provide.

  In order to solve the above-described problems, the present invention provides a swivel provided in a work machine having a main body, a swivel mounted on the main body so as to be swivel, and a work attachment provided on the swivel so as to be raised and lowered. An electric motor for driving the revolving structure to rotate, an operating means for receiving an input operation of a driving instruction for the electric motor, an operation amount detecting means capable of detecting an operation amount of the operating means, and the electric motor And a first target torque for driving the electric motor at a target speed corresponding to the operation amount detected by the operation amount detection means, and the speed detection means Based on the detected actual speed, a second target torque for holding the swivel body on the spot is set, and among the first target torque and the second target torque, the first target torque is set. Provides a work machine of the turning control apparatus, characterized in that a control means for actuating the electric motor in accordance with a large torque of the absolute value a torque in the same direction as the target torque.

  According to the present invention, since the second target torque is set based on the actual speed detected by the speed detection means, even when the work is performed in an environment where the work state fluctuates one by one, An in-situ holding torque (second target torque) suitable for the current working state can be specified. That is, the operation state of the work attachment (work attachment work radius, presence / absence of earth and sand in the bucket at the time of work), or external force received at the time of work (external force received at the time of pressing work by the bucket, the weight of the work machine itself on the slope) However, according to the present invention, even in such a case, the reversal of the revolving structure can be reliably prevented.

  Furthermore, in the present invention, since the high-order selection is performed between the second target torque calculated as described above and the second target torque calculated based on the operation amount of the operation means, the first target torque is selected. When the chart in which the one target torque and the second target torque change is examined (see FIG. 13), the torque selected at the point where these charts intersect (L8 in FIG. 13B) is changed. It will be. As described above, according to the present invention, unlike the prior art in which the control system is switched with a specific element other than the torque as a boundary, the first and second target torques are always compared and the larger one is adopted. Discontinuous fluctuations in torque can be suppressed.

  Specifically, the control means includes target speed setting means for setting the target speed based on the operation amount detected by the operation amount detection means, and the target speed and the actual speed detected by the speed detection means. First torque calculating means for calculating the first target torque based on the speed deviation from the first target torque and the second target torque, the torque in the same direction as the first target torque, and an absolute value Target torque setting means for setting a large torque as the next target torque.

  Further, the control means may include a second torque calculating means for calculating a torque to be applied to the electric motor as the second target torque in order to make the actual speed zero.

  The term “zero” is intended to include not only the case where the speed is completely zero, but also the case where the speed component within a range in which it can be determined that the speed is substantially zero is included. .

  The first torque calculating means and the second torque calculating means are configured to calculate the first target torque and the second target torque according to mathematical expressions each having a proportional term and an integral term, and the control means includes: It is preferable to further include a gain changing means capable of changing the magnitude of the gain that is multiplied by the proportional term and the integral term.

  According to this configuration, since each gain in the proportional integral control can be adjusted by the gain changing means, when the work radius of the work attachment is large, or when the inertial moment of the revolving structure is large such as work on an inclined ground, If the gain is changed to a larger value, the retrograde can be reliably prevented. On the other hand, in the case of performing a swivel pressing operation or the like using a bucket, the torque can be finely adjusted according to the operation of the operating means by changing the gain to a smaller value.

  Moreover, this invention provides the working machine provided with the body, the turning body mounted so that turning with respect to this body, and the said turning control apparatus.

  ADVANTAGE OF THE INVENTION According to this invention, the retrograde of a turning body can be prevented, suppressing the discontinuous fluctuation | variation of a torque.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view showing an overall configuration of an excavator according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the drive / control system of the shovel of FIG.

  1 and 2, an excavator 1 as an example of a work machine includes a crawler-type lower traveling body 2, an upper revolving body 3 that is turnably mounted on the lower traveling body 2, and an upper portion of the upper traveling body 3. And a work attachment 4 attached to the front portion of the revolving structure 3.

  The work attachment 4 includes a boom 5 attached to the upper swing body 3 so as to be raised and lowered, an arm 6 connected to the tip of the boom 5, a bucket 7 connected to the tip of the arm 6, and the boom A boom cylinder 8 for driving 5 with respect to the upper swing body 3, an arm cylinder 9 for driving the arm 6 with respect to the boom 5, and a bucket cylinder 10 for driving the bucket 7 with respect to the arm 6. Yes.

  The lower traveling body 2 includes a pair of left and right crawlers 11 (one is shown in FIG. 1), and each of the crawlers 11 is provided with a traveling motor 12.

  The upper-part turning body 3 includes an engine 14, a hydraulic pump 15 and a generator 16 driven by the engine 14, a battery 17, a turning electric motor 18, and a speed reduction mechanism 19 for the turning electric motor 18. .

As shown in FIG. 2, the hydraulic pump 15 is connected to the boom cylinder 8, the arm cylinder 9, the bucket cylinder 10, and the traveling motor 12 (hereinafter collectively referred to as hydraulic actuators 8 to 10 and 12) via control valves 20. To supply hydraulic oil. In other words, the operation of the hydraulic actuators 8 to 10 and 12 is controlled by adjusting the flow rate of hydraulic fluid from the hydraulic pump 15 to the hydraulic actuators 8 to 10 and 12 in accordance with the operation of the control valve 20.

  The generator 16 is connected to the output shaft of the engine 14 via the speed increasing mechanism 21. The electric power obtained by the generator 16 is charged to the battery 17 via the controller 22 and supplied to the turning electric motor 18 via the inverter 23. The controller 22 is for adjusting voltage application and current supply.

  The turning electric motor 18 includes a mechanical brake 24 as a negative brake for generating a mechanical braking force. In a state where the mechanical brake 24 is released, the driving force of the turning electric motor 18 is transmitted to the lower traveling body 2 via the turning deceleration mechanism 19, so that the upper turning body 3 with respect to the lower traveling body 2. Turns right or left.

  Further, the upper swing body 3 includes an operation lever 25. The operation lever 25 includes a lever portion 25a that can be tilted left and right from a preset neutral position, and an operation portion (for example, a potentiometer) 25b that detects an operation amount of the lever portion 25a. An electric signal corresponding to the operation amount is output to the controller 26 which is an example of the control means.

  Furthermore, the upper swing body 3 includes a speed sensor 27 that detects the rotational speed (turning speed) of the turning electric motor 18. The speed sensor 27 outputs an electrical signal corresponding to the rotational speed of the turning electric motor 18 to the controller 26.

  The controller 26 is a well-known control means including a CPU that executes various arithmetic processes, a ROM that stores initial settings, and a RAM that stores various information in a rewritable manner. The controller 26 stores a target speed map as shown in FIG.

  Specifically, in the target speed map of FIG. 3, both operating directions (right-handed rotation) of the lever portion 25a of the operating lever 25 are selected so that a larger target speed is selected as the operating amount (tilting angle) of the operating lever 25 increases. Turn or left turn direction). The target speed set in this map is set as a curve without a sudden increase / decrease so as to increase / decrease smoothly according to the increase / decrease of the operation amount of the operation lever 25.

  FIG. 4 is a block diagram showing an electrical configuration of the controller of FIG.

  Referring to FIG. 4, the controller 26 includes a target speed setting unit 28 that sets a target speed based on the target speed map, a correction amount calculation unit 29 that calculates a correction amount of the target speed, and the target speed. And a first torque calculation unit (first torque calculation means) 30 for calculating the first target torque based on the correction amount and the actual speed, and zero the speed detected by the speed sensor 27 (detected) A second torque calculation unit (second torque calculation means) 31 for calculating a second target torque to be applied to the turning electric motor 18 to maintain the state when the speed is zero), and the first target Target torque setting for setting the torque in the same direction as the direction of the first target torque (right turn direction or left turn direction) and having a large absolute value as the next target torque among the torque and the second target torque Department ( And a target torque setting means) 32.

  The target speed setting unit 28 specifies a target speed v0 corresponding to the operation amount a0 of the operation lever 25 from the target speed map (see FIG. 3).

  The correction amount calculation unit 29 detects the necessary torque t0 for turning the turning electric motor 18 that changes according to the working state of the excavator 1 at the current time. Here, the “working state of the excavator 1” means, for example, the working state of the work attachment 4 (work radius of the work attachment 4 or the presence or absence of earth and sand in the bucket 7 at the time of work), and the reaction force ( Reaction force received at the time of pressing work by the bucket 7, weight of the excavator 1 itself on an inclined ground, etc.). Specifically, in the present embodiment, the correction amount calculation unit 29 uses the target torque output from the inverter 23 one cycle before as an equivalent to the required torque t0 of the turning electric motor 18, and operates with the required torque t0. Based on the operation amount a0 of the unit 25b, the correction amount b0 is calculated according to the following formula 1.

  Here, G0 and G1 are control gains, respectively, and correspond to the intercept and the gradient when the operation amount a0 of the operation unit 25b is a variable. That is, the control gain G0 defines the maximum value of torque that can be limited. The larger the control gain G0, the smaller the target torque value that is finally calculated. On the other hand, the control gain G1 is for defining the rate of increase / decrease in torque that can be limited according to the change in the operation amount a0 of the operation lever 25. Then, by adjusting these control gains G0 and G1, an effect equivalent to bleed-off in the hydraulic turning system can be obtained.

  In the present embodiment, the target torque of one cycle before is used as the required torque t0 of the turning electric motor 18, but the target torque of the previous cycle and the turning torque detected by the speed sensor 27 are used. The actual required torque of the turning electric motor 18 may be calculated based on the speed of the electric motor 18.

  Then, as shown in the following Equation 2, the correction amount b0 calculated by the correction amount calculation unit 29 and the actual speed v1 of the turning electric motor 18 detected by the speed sensor 27 are subtracted from the target speed v0. A speed deviation Δv is calculated.

The first torque calculator 30 calculates a first target torque t1 according to the following formula 3 based on the speed deviation Δv.

  Here, G2 is a proportional gain, and G3 is an integral gain, which are preset.

  On the other hand, the second torque calculation unit 31 sets the actual speed v1 of the turning electric motor 18 detected by the speed sensor 27 to zero when the operation position of the lever part 25a of the operation lever 25 is within the neutral range described above. Therefore, the second target torque t2 to be applied to the turning electric motor 18 is calculated according to the following equation 4.

  Here, G4 is a proportional gain, and G5 is an integral gain, which are preset.

  Of the first target torque t1 and the second target torque t2, the target torque setting unit 32 determines the direction of the first target torque t1 (hereinafter, the right turning direction is “positive” and the left turning direction is “negative”. The torque having the same absolute value as that described in FIG. 5) and having a large absolute value is set as the next target torque.

  Hereinafter, processing executed by the controller 26 will be described with reference to FIGS. 4 and 5.

  When the process is started, first, a target speed v0 corresponding to the operation amount a0 of the operation lever 25 is specified based on the map (see FIG. 3) (step S1).

  Next, the speed sensor 27 detects the speed v1 of the turning electric motor 18 (step S2), and calculates the second target torque t2 according to the equation 4 based on the speed v1 (step S3).

  Then, the correction amount b0 is calculated according to the equation 1, and the speed deviation Δv is calculated according to the equation 2 using the correction amount b0 and the speed v1 (step S4).

  Next, the first target torque t1 is calculated according to the equation 3 using the speed deviation Δv (step S5), and it is determined whether or not the first target torque t1 is in the positive direction (right turn direction). (Step S6).

  If the first target torque t1 is in the positive direction (right turning direction) (YES in step S6), the first target torque t1 and the second target torque t2 are compared (step S7), Of the one target torque t1 and the second target torque t2, the torque in the positive direction and having a large absolute value is set as the next target torque (steps S8 and S9). Then, the target torque set in this way is output to the inverter 23 (step S15), and the process is terminated.

  On the other hand, if the first target torque t1 is not in the positive direction (NO in step S6), it is determined whether or not the first target torque t1 is in the negative direction (left turning direction) (step S10). .

  Here, when the first target torque t1 is in the negative direction (left turning direction) (YES in step S10), the first target torque t1 and the second target torque t2 are compared (step S11), Of the target torque t1 and the second target torque t2, the torque in the negative direction that has a large absolute value, that is, the smaller one that takes into account the positive or negative sign, is set as the next target torque (Steps S12 and S13). Then, the target torque set in this way is output to the inverter 23 (step S15), and the process is terminated.

  Further, when it is determined in steps S6 and S10 that the first target torque t1 is neither positive nor negative (NO in steps S6 and S10), that is, the upper swing body 3 is held on the spot. If necessary, the second target torque t2 is set as the next target torque (step S14), and then the target torque set in this way is output to the inverter 23 (step S15). End the process.

  By performing the processing as described above, torque control according to the operation of the operation lever 25 can be performed as shown in FIG.

  FIG. 6 shows the operation state, turning torque and turning speed of the operation lever 25 when the operation lever 25 is operated with the bucket 7 of the shovel 1 pressed against the ground.

  That is, in the state of FIG. 6, the operation lever 25 is operated in a state where the bucket 7 is pressed against the ground and the upper swing body 3 cannot swing. In such a case, if the PID control is performed without adding the necessary torque t0 as in the prior art, the target speed increases as the operation amount of the operation lever 25 increases, whereas the actual speed is zero. Therefore, the speed deviation becomes remarkably large, and as shown in the middle part of FIG. 7, there is a risk that the torque increases suddenly and a shock may occur. However, as in the above embodiment, the required torque of the turning electric motor 18 By reducing the speed deviation Δv by the correction amount b0 based on t0, it is possible to generate a turning torque corresponding to the operation of the operation lever 25 as shown in the middle part of FIG. This is also apparent from FIG. 8 showing the relationship between the operation amount of the operation lever 25 and the turning torque. FIG. 8 also shows the turning torque in a state where the bucket 7 is pressed against the ground and the upper turning body 3 cannot turn as in FIG.

  FIG. 9 shows the operation amount, turning speed, and turning torque of the operation lever when the required torque t0 generated in the upper turning body is relatively small.

  As shown in Equation 1 above, the correction amount b0 approaches zero as the required torque t0 decreases, so when the required torque t0 is small, speed control similar to that in the prior art that does not take the required torque t0 into account is performed. Can do. As a reference, FIG. 10 shows the operation amount, turning speed, and turning torque of the operation lever when the necessary torque t0 is not taken into account. The solid line in the turning speed column indicates the actual turning speed, and the two-dot chain line indicates the target speed corresponding to the operation amount of the operation lever 25.

  Further, in the embodiment, as described above, the first target torque t1 and the second target torque t2 that are in the same direction as the first target torque t1 and have a large absolute value are set as the next target torque. Therefore, the torque can be changed smoothly. This point will be described below in comparison with the conventional configuration.

  In the following description, the case where the target speed of the turning electric motor 18 changes as indicated by L2 as the operation amount L1 of the operation lever 25 is increased with time as shown in FIG. 11 will be described. To do. As is clear from the chart L2 rising from around 2 seconds, the operation range of the operation lever 25 within the range of 0 second to 2 seconds is a dead zone.

  For example, in the conventional technology disclosed in Japanese Patent Application Laid-Open No. 2003-328398, speed proportional control (PID control) is performed when the operation amount of the operation lever is within the range of the dead zone, while the operation amount of the operation lever exceeds the dead zone. In this case, torque control is performed. That is, when the torque transition L3 when the speed proportional control is performed as shown in FIG. 12A and the torque transition L4 for holding the upper swing body in place, the operation of the operation lever is considered. When the amount is gradually increased, as shown in FIG. 12 (b), the torque changes in accordance with the torque change L4 within the range of the dead zone from 0 second to 2 seconds, but exceeds the dead zone range. When the operation lever is operated, torque control according to the torque transition L3 is executed from that point, so that when the operation lever is operated up to the end of the dead zone, the discontinuous portion for interpolating the torque transitions L3 and L4 L5 will be generated.

  On the other hand, in the said embodiment, as shown to (a) of FIG. 13, the 2nd target for hold | maintaining the 1st target torque L6 when speed proportional control is performed, and the upper turning body 3 on the spot. The torque L7 is constantly compared, and a larger one of the first target torque L6 and the second target torque L7 is selected. Therefore, as shown in FIG. 13 (b), in the present embodiment, regardless of the operation amount of the operation lever 25, the first target torque L6 and the second target torque L7 are used as a boundary at the intersection portion L8. It is possible to continuously switch between the one target torque L6 and the second target torque L7. Therefore, according to this embodiment, smooth and stable control can be performed.

  As described above, according to the embodiment, since the second target torque t2 is set based on the actual speed detected by the speed sensor 27, the work is performed in an environment where the work state fluctuates one by one. Even in such a case, the in-situ holding torque (second target torque t2) suitable for the current working state can be specified. That is, the operation state of the work attachment 4 (work radius of the work attachment 4 or the presence or absence of earth and sand in the bucket 7 at the time of work), or external force received at the time of work (external force received at the time of pressing work by the bucket 7, work machine itself on an inclined ground) The in-situ holding torque fluctuates one by one depending on the weight of the upper revolving body, etc., but according to the embodiment, it is possible to reliably prevent the revolving of the upper swing body even in such a case. .

  Further, in the embodiment, a high-order selection is made between the second target torque t2 calculated as described above and the second target torque t2 calculated based on the operation amount of the operation lever 25 (step S6 in FIG. 5). To S14), when the charts L6 and L7 in which the first target torque t1 and the second target torque t2 change are examined (see FIG. 13), the intersection of the charts L6 and L7. The torque selected with the portion L8 as a boundary is changed. As described above, according to the embodiment, unlike the conventional technique in which the control system is switched with a specific element other than the torque as a boundary, the first and second target torques t1 and t2 are always compared in magnitude and the larger one is adopted. Therefore, discontinuous fluctuations in torque can be suppressed.

  In the above-described embodiment, the gain G2, G3, G4, and G5 in Formula 3 and Formula 4 are fixed at preset values. However, each gain G2 to G5 is assigned to the controller 26. Gain changing means for changing the value can be provided.

  In this way, since the gains G2 to G5 can be adjusted by the gain changing means, when the work radius of the work attachment 4 is large, or when the moment of inertia of the revolving structure is large, such as work on an inclined land, If the gains G2 to G5 are set larger, the retrograde can be reliably prevented. On the other hand, when performing a turning pressing operation by the bucket 7 or the like, the torque can be finely adjusted according to the operation of the operation lever 25 by changing the gain to a smaller value.

  Further, in the above embodiment, the target torque of the turning electric motor 18 according to the required torque t0 (target torque before one cycle) for turning the upper turning body 3 that changes according to the working state of the upper turning body 3. Since it is comprised so that the magnitude | size of may be adjusted, generation | occurrence | production of a shock can be suppressed effectively.

  That is, also in the excavator 1, the working state thereof, for example, the working state of the work attachment 4 (work radius of the work attachment 4, or the presence or absence of earth and sand in the bucket 7 at the time of work), or the external force (bucket 7) received during the work. The required torque t0 changes according to the reaction force received during the pressing operation by the sway, the weight of the excavator 1 itself on the slope, etc.). Therefore, as the required torque t0 increases, the target speed and the actual speed v1 detected by the speed detection means However, in the above-described embodiment, the speed deviation Δv can be prevented from becoming large.

  Specifically, in the above embodiment, the larger the required torque t0, the larger the correction value b0 is calculated and the correction value b0 is subtracted from the already set target speed v0. The speed deviation Δv between v0−b0) and the actual speed v1 detected by the speed sensor 27 can be reduced.

Therefore, according to the embodiment, the speed deviation Δv can be reduced as the required torque t0 is increased, so that the occurrence of shock can be suppressed.

  By adopting a configuration in which the smaller the correction amount b0 is calculated as the operation amount a0 of the operation lever 25 is larger as in the embodiment, the corrected target speed as the operation amount a0 of the operation lever 25 increases. Can be suppressed from becoming too small, and the uncomfortable feeling given to the operator can be alleviated.

  As in the above-described embodiment, by using the previously set target torque as the required torque t0 to be used this time, the processing is simpler than when the required torque t0 of the upper swing body 3 is actually calculated. Can be achieved.

  In other words, all changes in the required torque t0 of the upper swing body 3 are reflected in the load torque (target torque) of the turning electric motor 18, so the correction value b0 is calculated according to the increase or decrease of the load torque and the target torque is calculated. By calculating, the target torque commensurate with the change in the required torque t0 can be calculated.

  As in the above-described embodiment, the target torque setting unit that sets the torque in the same direction as the first target torque t1 out of the first target torque t1 and the second target torque t2 and having a large absolute value as the target torque With the configuration provided with 32, the upper swing body 3 turns in the opposite direction due to insufficient torque when starting to turn upward on an inclined ground or when starting to turn upward on a strong wind. The occurrence of “reverse” can be reliably prevented.

  In addition, even when turning is stopped on an inclined ground, the torque of the turning electric motor 18 is always at a magnitude that suspends from gravity, so that it is possible to prevent the upper turning body 3 from going backwards due to the braking torque being lost to gravity. it can.

The side view which shows the whole structure of the shovel which concerns on embodiment of this invention is shown. It is a block diagram which shows the structure of the drive and control system of the shovel of FIG. FIG. 3 is a map stored in the controller of FIG. 2 in which the operation amount of the operation lever is associated with the target speed. FIG. 3 is a block diagram showing an electrical configuration of the controller of FIG. 2. It is a flowchart which shows the process performed by the controller of FIG. The operation state, turning torque, and turning speed of the operation lever when the operation lever is operated with the shovel bucket pressed against the ground are shown. FIG. 7 is a view corresponding to FIG. 6 when the necessary torque t0 is not taken into consideration. It is a graph which shows the relationship between the operation amount of an operation lever, and turning torque in the state of FIG. The operation amount of the operation lever, the turning speed, and the turning torque when the required torque generated in the upper turning body is relatively small are shown. FIG. 10 is a diagram corresponding to FIG. 9 when the necessary torque t0 is not taken into account. It is a graph which shows the relationship between the operation amount of an operation lever, and the target speed of an electric motor. It is a graph which shows the control which concerns on the prior art, (a) shows the torque transition of speed proportional control, and the transition of the torque for in-situ maintenance, (b) shows torque control from speed proportional control. It shows the state of switching to. It is a graph which shows the control which concerns on this invention, (a) shows the torque transition of speed proportional control, and the transition of the torque for in-situ maintenance, (b) is from speed proportional control to torque control. It shows the state of switching.

Explanation of symbols

1 Excavator (work machine)
2 Lower traveling body 3 Upper revolving body 4 Work attachment 18 Electric motor for turning 23 Inverter (moment specifying means)
25 Operation lever (operation means)
26 controller (control means)
27 Speed sensor (speed detection means)
28 Target speed setting unit 29 Correction amount calculating unit 30 First torque calculating unit 31 Second torque calculating unit 32 Target torque setting unit

Claims (5)

A swivel control device provided in a work machine having a main body, a swivel body mounted on the main body so as to be turnable, and a work attachment provided on the swivel body in a undulating manner,
An electric motor for rotationally driving the revolving structure;
An operation means for receiving an input operation of a drive instruction for the electric motor;
An operation amount detection means capable of detecting an operation amount of the operation means;
Speed detecting means capable of detecting the rotational speed of the electric motor;
A first target torque for driving the electric motor at a target speed corresponding to the operation amount detected by the operation amount detection means is set, and the revolving body is based on the actual speed detected by the speed detection means. The second target torque is set to be held on the spot, and among these first target torque and second target torque, the torque is in the same direction as the first target torque and has a large absolute value. A turning control device for a work machine, comprising: a control means for operating the electric motor.   The control means includes a target speed setting means for setting the target speed based on the operation amount detected by the operation amount detection means, and a speed deviation between the target speed and an actual speed detected by the speed detection means. A first torque calculation means for calculating the first target torque based on the first target torque and a second target torque, wherein the torque is in the same direction as the first target torque and has a large absolute value. 2. The turning control device for a work machine according to claim 1, further comprising target torque setting means for setting as a next target torque.   The said control means is further provided with the 2nd torque calculating means which calculates the torque which should be given to the said motor in order to make the said actual speed zero as said 2nd target torque. Swivel control device for work machines.   The first torque calculating means and the second torque calculating means are configured to calculate a first target torque and a second target torque according to mathematical formulas having a proportional term and an integral term, respectively, and the control means 4. The turning control device for a work machine according to claim 3, further comprising gain changing means capable of changing the magnitude of the gain on the term and the integral term.   The working machine provided with the body, the turning body mounted in this body so that turning is possible, and the turning control apparatus of any one of Claims 1-4.

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