JP5723947B2 - Construction machine having a rotating body - Google Patents

Description

  The present invention relates to a construction machine having a swivel body such as a hydraulic excavator.

  A construction machine such as a hydraulic excavator uses a fuel such as gasoline or light oil as a power source and drives a hydraulic pump by an engine to generate hydraulic pressure, thereby driving a hydraulic actuator such as a hydraulic motor or a hydraulic cylinder. Hydraulic actuators are small and light and capable of high output, and are widely used as construction machine actuators.

  On the other hand, in recent years, as described in Patent Document 1, by using an electric actuator driven by an electric motor, energy efficiency is improved compared to a construction machine using only a hydraulic actuator driven by hydraulic energy of a hydraulic pump. Construction machines have been proposed that improve energy consumption and save energy.

  The hydraulic actuator performs the regeneration by accumulating the kinetic energy in an accumulator provided on the hydraulic circuit or converts the hydraulic pressure to electricity, whereas in the case of an electric actuator, the kinetic energy during braking is Since it can be directly regenerated as electric energy, it has a feature that is superior in energy compared to a hydraulic actuator.

  For example, in the prior art disclosed in Patent Document 1, a hydraulic excavator equipped with an electric motor as an actuator for driving a revolving structure is shown. An actuator that turns an upper swing body of a hydraulic excavator with respect to a lower traveling body is frequently used, and frequently accelerates and decelerates during work.

  For example, when excavating soil and loading it onto a dump truck, when the bucket is filled with the excavated earth and sand, it accelerates to the dump truck, accelerates and decelerates in front of the dump truck, and releases it just above the dump truck. Soil. After that, the vehicle accelerates to the excavation site, decelerates in front of the excavation site, stops and excavates at the excavation site. This is a repetitive operation.

  At that time, when hydraulic regeneration is not performed, during deceleration, that is, during braking, the kinetic energy of the swivel body with a large inertia load is calculated based on the set pressure of the relief valve in the case of a hydraulic motor. By returning to the tank, it is discarded as heat on the hydraulic circuit.

  On the other hand, in the case of an electric motor, since the electric motor functions as a generator by a rotating body having a large inertia load, the output from the electric motor can be regenerated as electric energy. From this point of view, it is considered effective to use an electric motor instead of a hydraulic motor from the viewpoint of energy saving.

  However, when an electric motor is used for turning a construction machine, the following problems caused by the characteristics of the electric motor occur.

  First, in order to keep the rotating body stopped by the electric motor, it is necessary to compare the actual speed and the target speed in the speed control and perform speed feedback control that performs speed control based on the obtained control amount. . However, speed feedback control tends to cause hunting due to the influence of time delay. In addition, when an electric motor is used, the operational feeling is determined by the control, and therefore, an operational discomfort may occur depending on the control performance. Furthermore, in the operation of continuously outputting torque without rotating the electric motor, for example, in excavating a groove, swinging the boom, arm and bucket while pressing the side surface of the bucket against the inner surface of the groove by slightly operating the swivel body In the excavation work to be performed, there is a problem that the electric motor and the inverter are overheated. Further, when an electric motor that guarantees an output equivalent to a hydraulic motor is used, there is a problem that the outer shape becomes too large or the cost becomes remarkably high.

  In order to solve the above problems, a construction machine that implements both the hydraulic motor and the electric motor and drives or brakes the swivel body with a total torque while realizing energy saving is disclosed in Patent Document 2 and Patent It is disclosed in Document 3.

  The prior art disclosed in Patent Document 2 discloses an energy regeneration device for a hydraulic construction machine in which a swing electric motor is directly connected to a swing hydraulic motor, and a controller commands an output torque to the electric motor based on an operation amount of a swing operation lever. Has been. In this prior art, at the time of deceleration, that is, at the time of braking, the electric motor regenerates the kinetic energy of the revolving body and stores it in the battery as electric energy.

  In the prior art disclosed in Patent Document 3, a hybrid construction that calculates a torque command value to the electric motor by using a differential pressure between meter-in and meter-out of the hydraulic motor and distributes output torque between the hydraulic motor and the electric motor. A machine is disclosed.

  In the conventional techniques of Patent Document 2 and Patent Document 3 described above, both a hydraulic motor and an electric motor are used as a turning actuator. Therefore, sufficient driving torque that can drive the revolving structure is ensured, and electric energy is collected by the electric motor. In addition, the drive system of the swivel body in the construction machine is configured to be simple and easy to put into practical use to save energy.

Japanese Patent No. 3647319 Japanese Patent No. 4024120 JP 2008-63888 A

  However, there are the following problems in the above-described prior art.

  For example, in the prior art described in Patent Document 2, it is disclosed that a torque command value for a swing electric motor is calculated based on an operation amount of a swing operation lever. However, it does not take into account changes in the torque of the swing hydraulic motor due to the effects of the posture of the front part of the construction machine consisting of buckets, booms and arms, the load, and the inclination of the road surface on which the construction machine is working.

  Therefore, the total torque of the torque of the swing electric motor and the torque of the swing hydraulic motor output based on the torque command value to the swing electric motor may not be a desired torque corresponding to the swing lever operation amount.

  Further, in the prior art described in Patent Document 3, a torque command value to the electric motor is calculated based on a differential pressure generated in two ports which are an oil suction port and a discharge port installed in the hydraulic motor. Yes. However, it is not considered that the torque of the hydraulic motor changes depending on the operation amount of the turning operation lever, and the ratio of the torque between the hydraulic motor and the electric motor is controlled to be constant regardless of the operation amount of the turning operation lever. ing. Therefore, there is a possibility that a desired torque corresponding to the operation amount of the turning operation lever cannot be obtained in consideration of the torque of the hydraulic motor that changes based on the operation amount of the turning operation lever.

  Therefore, an object of the present invention is to provide a hybrid construction machine that ensures good operability of the revolving structure and has high energy efficiency.

  In order to solve the above object, for example, a swing hydraulic motor driven by hydraulic pressure generated by a hydraulic pump driven by an engine, a swing electric motor connected to the swing hydraulic motor and driven by electric power from an electric storage device, A swing body connected to the swing electric motor, and the swing body is controlled and driven by the total torque of the swing electric motor and the swing hydraulic motor that are controlled according to the operation amount of the swing operation lever for operating the swing body. In the construction machine, the electric motor torque command value input to the swing electric motor to control and drive the swing electric motor is obtained by multiplying the torque of the swing hydraulic motor by a gain set according to the operation amount of the swing operation lever. It is characterized by calculating.

  ADVANTAGE OF THE INVENTION According to this invention, in a hybrid type construction machine which has a turning body, favorable operativity can be provided and high energy efficiency can be implement | achieved.

1 is a side view of a hydraulic excavator according to the present invention. 1 is a system configuration diagram of a hydraulic excavator according to the present invention. 1 is a detailed view of a hydraulic system of a hydraulic excavator according to the present invention. The bleed-off opening area diagram of a turning spool. The meter-out opening area diagram of a turning spool. The system block diagram at the time of setting it as the hydraulic system which switches the relief pressure of the hydraulic motor in FIG. 3 with a switching valve. The control flow figure of A port side relief valve. The control flow figure of a B port side relief valve. The control flow figure of a turning electric motor. The figure which shows the example of the drive gain table used by control of a turning electric motor. The figure which shows the example of the braking gain table used by control of a turning electric motor. FIG. 4 is a system configuration diagram of a hydraulic excavator according to a second embodiment. The bleed-off opening area diagram of the turning spool in Example 2. FIG. The meter-out opening area diagram of the turning spool in Example 2. FIG. The distribution diagram of the turning hydraulic motor torque and the turning electric motor torque with respect to the pilot pressure in the present embodiment.

  As described above, in calculating the torque command value for the swing electric motor, by not considering the torque change of the swing hydraulic motor due to the attitude of the front part, the working environment of the construction machine, the operation amount of the swing lever, etc. A desired torque according to the amount of operation of the turning lever may not be obtained for the turning body. As a result, it is not possible to obtain braking / driving of the revolving body according to the amount of operation of the revolving lever, and the operator feels uncomfortable with the operability.

  Therefore, the present invention discloses a technique for calculating a torque command value for the swing electric motor so that the torque applied to the swing body by the swing hydraulic motor and the swing electric motor becomes a torque corresponding to the lever operation amount. .

  Furthermore, the present invention realizes a hybrid construction machine that guarantees the basic performance of an excavator with a hydraulic system even if the torque of the swing electric motor cannot be generated for some reason. In the prior art, since the swing electric motor is responsible for a certain torque of the entire swing torque, for example, there is an energy shortage or an overdischarge state of the power storage device, a failure or abnormality of an electric system such as an inverter or a motor. As a result, if the torque from the swing electric motor cannot be obtained, a state in which a desired swing torque cannot be obtained may occur. In the present invention, in order to solve such a problem, a hybrid type construction machine that guarantees the basic performance of an excavator with a hydraulic system even when a swing electric motor fails is realized.

  For this purpose, the present invention has a combined swing mode of a swing hydraulic motor and a swing electric motor and a swing hydraulic motor single swing mode, and each mode is switched and driven. When the lever is in a state in which the turning operation lever is not operated and in a state in which the turning operation lever is operated up to the maximum operation amount, the turning body is driven in the hydraulic motor single turning mode. Hereinafter, the state in which the turning lever is not operated is referred to as a neutral state, and the state in which the turning lever is operated up to the maximum operation amount is referred to as a maximum state.

  On the other hand, when the turning operation lever is in a position larger than the neutral state and smaller than the maximum state, the combined turning mode is set. Hereinafter, the region larger than the neutral state and smaller than the maximum state is referred to as an intermediate region. Further, in this combined turning mode, for example, as shown in FIG. 15, the torque distribution ratio between the swing hydraulic motor and the swing electric motor is configured so that the ratio of the torque of the swing electric motor to the swing hydraulic motor is maximized in the intermediate region. By doing so, energy-saving operation is performed. In this way, by having a configuration in which the hydraulic motor has a single turning mode and a composite turning mode, and switches them according to the amount of operation of the turning lever, the performance of the work machine is basically guaranteed in the turning hydraulic motor, Energy saving can be realized by braking and driving the electric rotating motor. In particular, when the swing operation lever is in the neutral state and the maximum state, it is configured to be in the hydraulic motor single swing mode, so that it can be started / stopped in the same way as normal regardless of the failure of the power storage device. .

  In the following embodiments, the present invention will be described in detail.

  FIG. 1 shows a side view of a hydraulic excavator according to the first embodiment. In FIG. 1, the lower traveling body 10 is composed of a pair of crawlers 11 and a crawler frame 12 that are shown only on one side in FIG. 1. Moreover, it has a pair of driving | running | working hydraulic motors 13 and 14 which are not illustrated in FIG. 1, and drives and controls each crawler 11 independently. A speed reduction mechanism and the like are also installed in the lower traveling body 10.

  The swing body 20 includes a swing frame 21, an engine 22, an assist power generation motor 23, a swing electric motor 25, a capacitor 24, a swing mechanism 26, a swing hydraulic motor 27, a reduction mechanism (not shown), and the like. The rotation shaft of the motor 27 is coupled, and the swing electric motor 25 and the swing hydraulic motor 27 coupled by the rotation shaft control and drive the swing body 20 via the swing mechanism 26.

  The engine 22 is provided on the turning frame 21. The capacitor 24 is connected to an assist power generation motor 23 provided coaxially with the engine 22 and a swing electric motor 25 provided coaxially with the swing hydraulic motor 27 and the swing mechanism 26. The capacitor 24 is charged and discharged by the braking and driving of the electric motor 23 and the swing electric motor 25. The turning mechanism 26 turns the turning body 20 and the turning frame 21 with respect to the lower traveling body. The speed reduction mechanism decelerates the rotation of the turning electric motor 25.

  The revolving unit 20 includes a boom 31, a boom cylinder 32 for driving the boom 31, an arm 33 rotatably supported near the tip of the boom 31, an arm cylinder 34 for driving the arm 33, An excavator mechanism 30 including a bucket 35 rotatably supported at the tip of the arm 33 and a bucket cylinder 36 for driving the bucket 35 is mounted.

  Further, hydraulic actuators such as traveling hydraulic motors 13 and 14 (not shown in FIG. 1), a swing hydraulic motor 27, a boom cylinder 32, an arm cylinder 34, and a bucket cylinder 36 are driven on the swing frame 21 of the swing body 20. A hydraulic system 41 including a hydraulic pump 41 (not shown) and a control valve 42 for driving and controlling each actuator is mounted. The hydraulic pump 41 is driven by the engine 22.

  FIG. 2 shows a system configuration diagram of main electric and hydraulic equipment of the excavator according to the first embodiment. As shown in FIG. 2, the driving force of the engine 22 is transmitted to the hydraulic pump 41. Further, the control valve 42 is supplied with hydraulic oil discharged from the hydraulic pump 41 through the hydraulic pipe 43, and in response to a command (operation direction and operation amount) from a swing operation lever (not shown), the swing hydraulic motor 27, the boom cylinder 32, the discharge amount and the discharge direction of hydraulic oil to the arm cylinder 34, the bucket cylinder 36 and the traveling hydraulic motors 13 and 14 are controlled.

  The capacitor 24 is connected to a chopper 51, and the DC power of the capacitor 24 is boosted to a predetermined bus voltage via the chopper 51. The voltage boosted to a predetermined value is input to a swing electric motor inverter 52 for braking / driving the swing electric motor 25 and an assist power generation motor inverter 53 for braking / driving the assist power generation motor 23. The assist generator motor inverter 53 is connected to the chopper 51 via a smoothing capacitor 54, and the smoothing capacitor 54 is provided to stabilize the bus voltage.

  An A port side relief valve 28 and a B port side relief valve 29 are provided at the inlet / outlet ports of the hydraulic oil of the swing hydraulic motor 27, respectively. As shown in FIG. 3, the turning hydraulic motor 27 has two ports that serve as an inlet and an outlet for hydraulic oil. In this specification, a port that serves as an inlet for the hydraulic oil when turning left is designated as an A port and an outlet. The port which becomes the B port, the port which becomes the inlet of the hydraulic oil when turning right is defined as the B port, and the port which becomes the outlet is defined as the A port. The A port side relief valve 28 and the B port side relief valve 29 are composed of electromagnetic variable relief valves and control the A port pressure and the B port pressure of the swing hydraulic motor 27, respectively.

  Although not shown, pressure sensors for detecting the A port pressure and the B port pressure are provided.

  The controller 80 controls the hydraulic pump 41, the A port side relief valve 28, and the B port side relief valve 29 using a swing operation lever operation amount, a swing hydraulic motor pressure, a swing hydraulic motor rotation speed, and the like (not shown). Further, the power control unit 55 is controlled. The electric / hydraulic signal conversion device 75 converts an electric signal from the controller 80 into a hydraulic pilot signal, and corresponds to, for example, an electromagnetic proportional valve.

  FIG. 3 shows details of the hydraulic system of the hydraulic excavator according to the first embodiment.

  The turning operation lever 72 has a pressure reducing valve function for reducing the pressure from a pressure source (not shown) according to the operation amount, and the turning spool provided in the control valve 42 with the operation pressure corresponding to the operation amount of the turning operation lever 72. 44 is applied to either the left or right pressure chamber. The swing spool 44 controls the flow rate of hydraulic oil supplied from the hydraulic pump 41 to the swing hydraulic motor 27 by controlling the switching amount (spool stroke) according to the operation pressure acting on the pressure chamber. Due to the operation pressure from the lever 72, the swivel spool 44 is continuously switched from the neutral position O to the A position or the B position.

  For example, when the turning operation lever 72 is in the neutral state, when the turning spool 44 is in the neutral position O, the hydraulic oil discharged from the hydraulic pump 41 returns to the tank through the bleed-off throttle.

  On the other hand, for example, when the turning operation lever 72 is operated to turn left, the turning spool 44 is switched to the A position, the opening area of the bleed-off stop is reduced, and the openings of the meter-in stop and the meter-out stop are opened. Increases area. The hydraulic oil discharged from the hydraulic pump 41 is sent to the A port of the swing hydraulic motor 27 through the meter-in throttle at the A position, and the return oil from the swing hydraulic motor 27 passes through the meter-out throttle at the A position to the tank. Return. By performing such hydraulic oil control, the swing hydraulic motor 27 rotates to the left.

  Further, for example, when the turning operation lever 72 is operated to make a right turn, the turning spool 44 is switched to the B position, the opening area of the bleed-off stop is reduced, and the meter-in stop and the meter-out stop are turned on. The opening area increases. The hydraulic oil discharged from the hydraulic pump 41 is sent to the B port of the swing hydraulic motor 27 through the B-position meter-in throttle, and the return oil from the swing hydraulic motor 27 returns to the tank through the B-position meter-out throttle. . By performing such control of the hydraulic oil, the swing hydraulic motor 27 rotates to the right in the direction opposite to that in the A position.

  When the swing spool 44 is positioned between the neutral position O and the A position, the hydraulic oil discharged by the hydraulic pump 41 is distributed to the bleed-off throttle and the meter-in throttle. The same applies to the case between the neutral position O and the B position.

  The A port side relief valve 28 is provided between the A port of the swing hydraulic motor 27 and the swing spool 44. Further, the B port side relief valve 29 is provided between the B port of the swing hydraulic motor 27 and the swing spool 44. The A port side relief valve 28 and the B port side relief valve 29 are configured such that the relief pressure on each port side can be changed in accordance with a command from a controller 80 (not shown in FIG. 3).

  Although the relief valves 28 and 29 are electromagnetic variable relief valves, the relief valve to be used is switched between the high pressure side 28a and 29a and the low pressure side 28b and 29b by the switching valves 28c and 29c in the configuration shown in FIG. It may be a method.

  In FIG. 4, a bleed-off opening area diagram showing the bleed-off opening area with respect to the spool stroke of the orbiting spool 44 in this embodiment is shown by a broken line. Here, since the spool stroke changes only depending on the turning lever operation amount, it may be considered as the turning lever operation amount. Further, for example, in a conventional construction machine that drives a swing body by a swing hydraulic motor alone, an opening area of the swing hydraulic motor that can ensure good operability is indicated by a solid line. The size of the bleed-off opening area of the orbiting spool 44 in this embodiment is substantially the same as the opening area indicated by the solid line when the turning point 72 is at the start point and the end point, that is, when the turning operation lever 72 is in the neutral state and the maximum state. It is set to be wider than the conventional machine.

  Here, when the opening area of the bleed-off throttle of the swing spool 44 is increased, the drive torque obtained by the swing hydraulic motor 27 is decreased. Therefore, in the case of having an opening area characteristic as in the present embodiment, the drive torque of the turning hydraulic motor 27 when the turning operation lever is in the intermediate region is compared with the driving torque generated in the turning spool having the opening area indicated by the solid line. Then, it is set to be smaller. On the other hand, when the turning operation lever is in the neutral state and the maximum state, the opening area is set to be substantially the same as the opening area indicated by the solid line, and therefore the driving torque of the turning hydraulic motor is substantially the same.

  FIG. 5 is a meter-out opening area diagram showing the meter-out opening area with respect to the spool stroke of the orbiting spool 44 in this embodiment. Similar to FIG. 4, the spool stroke changes only depending on the amount of operation of the turning lever, so it may be considered as the amount of operation of the turning lever. Further, for example, in a construction machine that drives a swing body by a swing hydraulic motor alone, an opening area of the swing hydraulic motor that can ensure good operability is indicated by a solid line. The size of the meter-out opening area of the swivel spool 44 in this embodiment is such that the starting point and the ending point are substantially the same as the opening area indicated by the solid line, and the opening area indicated by the solid line in the present invention is the middle area. It is set to be wider. As described above, since the magnitude of the braking torque depends on the size of the opening area of the meter-out aperture, the braking torque of the turning hydraulic motor 27 when the turning lever operation amount is in the intermediate range is the same as that of the conventional turning hydraulic motor. It becomes smaller than the braking torque. Further, in the neutral and maximum states of the turning lever operation amount, the opening area is substantially the same as the solid line opening area, so that the magnitude of the braking torque of the turning hydraulic motor 27 is set to be substantially the same.

  As described above, the magnitude of braking and driving torque of the swing hydraulic motor is determined in accordance with the bleed-off opening area and meter-out opening area of the swing spool 44 determined with respect to the operation amount of the swing operation lever. .

  FIG. 7 is a flowchart showing a method for controlling the A port side relief valve 28. 7 is performed every control cycle of the controller 80.

  Start the excavator system. At startup, the relief pressure of the A port is normally set to a predetermined value. First, in step S1, it is determined whether or not the relief pressure of the A port is a normal predetermined value. When it is a normal predetermined value, it progresses to step S2, and the A port pressure of the present turning hydraulic motor 27 is compared with the preset threshold value P1. When the A port pressure is smaller than the threshold value P1, the process proceeds to step S3, where the motor rotational speed is smaller than a preset positive value N-1 times the threshold value N1, or the operation amount of the left turning operation lever ( Hereinafter, it is determined whether or not the left turn operation amount is larger than a preset threshold value L1. If it is determined that the motor speed is smaller than −1 times the preset threshold value N1 or the left turn operation amount is greater than the preset threshold value L1, in step S4 A process to lower the relief pressure of the A port is performed. On the other hand, if it is not determined in step S3 that the motor rotational speed is smaller than the preset positive value threshold value N1 minus -1 times or the left turn operation amount is larger than the preset threshold value L1. Returning to step S1, it is determined again whether the relief pressure of the A port is a normal predetermined value.

  If it is determined in step S2 that the A port pressure is greater than the threshold value P1, the process returns to step S1 to determine again whether the A port relief pressure is a normal predetermined value.

  Here, the motor rotation speed is defined as positive for left turn and negative for right turn, and the rotation speeds of the swing electric motor 25 and the swing hydraulic motor 27 are the same. The threshold value P1 is set to a value equal to or lower than the relief pressure when the relief pressure is lowered, and the threshold value N1 and the threshold value L1 are set to values near zero. When the motor rotation speed is smaller than -N1, the A port is on the meter-out side of the swing hydraulic motor 27. When the left swing operation amount is larger than L1, the A port is connected to the swing hydraulic motor 27. It is on the meter-in side.

  If it is determined in step S1 that the relief pressure at the A port is not a normal predetermined value, the motor rotation speed is larger than −1 times the threshold value N2 which is a positive value set in advance in step S5, and the left turn operation amount Is smaller than a preset threshold value L2. If it is determined that the above condition is satisfied, the process proceeds to step S6, and the relief pressure of the A port is returned to the normal value. If the above condition is not satisfied, the process returns to step S1 to determine again whether the relief pressure of the A port is a normal predetermined value. Here, N2 and the threshold value L2 are values near zero. The threshold value N1 is set to a value equal to or greater than N2, and the threshold value L1 is set to a value equal to or greater than L2.

  Here, the condition of step S2 may be omitted. That is, the determination of the A port pressure in FIG. 7 may always be “yes”. Further, step S3 and step S5 may be performed only for the motor rotation speed condition, and not for the left turn operation amount condition, that is, the relief pressure on the meter-in side may not be changed. In this case, in the control method to be described later, the driving torque of the swing electric motor 25 is not easily increased, and it is difficult to discharge. Steps S3 and S5 may be limited to the condition of the left turn operation amount, and the condition of the motor rotational speed may not be used, that is, the relief pressure on the meter-out side may not be changed. In this case, in the control method to be described later, the braking torque of the swing electric motor 25 is not easily increased, and charging is difficult.

  Also, when the condition of the motor rotational speed is satisfied in step S3 and when the condition of the left turn operation amount is satisfied, the relief pressure reduction method is changed, that is, the relief pressure is decreased on the meter-out side and the meter-in side. May be changed. For example, if the relief method for reducing the relief pressure on the meter-out side is made larger than that on the meter-in side, in the control method described later, the braking torque of the swing electric motor 25 tends to be larger than the drive torque, and charging becomes easy.

  FIG. 8 is a flowchart showing a method for controlling the B port side relief valve 29. The control method is the same as that in FIG. 7 except that the turning direction is reversed on the left and right, and the positive and negative of the motor rotation speed are reversed accordingly.

  The braking / driving torque of the swing hydraulic motor can be reduced by lowering the relief pressure of the A port and the B port based on the control flow as shown in FIGS.

  In this embodiment, the swing hydraulic motor torque is reduced by setting the opening area of the swing spool and performing the relief pressure control. However, the swing hydraulic motor is configured by taking either one of the configurations. A configuration that reduces the torque may be adopted.

  Hereinafter, a control method of the swing electric motor will be described. FIG. 9 is a flowchart showing a method for controlling the swing electric motor 25. 9 is performed every control cycle of the controller 80.

  First, the hydraulic motor torque is calculated from the difference between the A port pressure and the B port pressure of the swing hydraulic motor 27 detected by a pressure sensor (not shown) in step S10. Next, in step S11, it is determined based on the hydraulic motor torque whether the swing hydraulic motor 27 is generating driving torque or braking torque. For example, if the A port pressure is larger than the B port pressure and the motor rotation direction is the left turning direction, it is determined that the drive torque is generated. When such a determination is made and it is determined that the swing hydraulic motor 27 is generating a drive torque, a swing electric motor torque command value T1 is calculated using a drive gain table in step S12. The drive gain table used here includes, for example, a drive gain determined in accordance with the turning lever operation amount as shown in FIG. 10, and this drive gain is the bleed-off opening area of the turning spool 44 shown in FIG. It is determined based on characteristics. The bleed-off opening area shown in FIG. 4 is compared with the driving torque of the swing hydraulic motor as used when the swing operation lever 72 is in the intermediate region, when the swing drive is performed by the hydraulic motor alone, The drive torque of the swing hydraulic motor is set to be small, and the drive gain is set so that the drive gain becomes maximum when the swing operation lever 72 is in the intermediate region as shown in FIG. In step S12 described above, a value obtained by multiplying the drive gain determined using the drive gain table by the hydraulic motor torque described above is obtained as the electric motor torque command value T1.

  On the other hand, if step S11 is negative and it is determined that the turning hydraulic motor 27 is generating braking torque, the turning electric motor torque command value T1 is calculated using the braking gain table in step S13. The braking gain table used here includes, for example, a braking gain determined in accordance with the turning lever operation amount as shown in FIG. 11, and this braking gain table is a meter-out opening area of the turning spool 44 shown in FIG. It is determined based on the characteristics of the diagram. The meter-out opening area shown in FIG. 5 is compared with the braking torque of the swing hydraulic motor used when the swing operation lever 72 drives the swing by the hydraulic motor alone in the intermediate region. The braking torque is set to be small, and the braking gain is set so that the braking gain becomes maximum when it is in the middle region of the turning operation lever 72 as shown in FIG. A value obtained by multiplying the braking gain determined by the turning hydraulic motor torque is an electric motor torque command value T1.

  As described above, the turning electric motor torque command value T1 is a command value in consideration of the turning operation amount and the hydraulic motor torque. By controlling the swing electric motor based on the swing electric motor torque command value T1, the desired swing electric motor torque is changed by the change in the swing hydraulic motor torque caused by the front posture of the construction machine, the load, the swing lever operation amount, and the like. A situation in which the motor torque cannot be obtained can be avoided. Therefore, in the combined turning mode controlled by the turning hydraulic motor and the turning electric motor, it is possible to obtain torque according to the operation amount of the turning operation lever, and the operator can set the desired swing body according to the operation of the turning operation lever. It is possible to operate at an acceleration / deceleration and to obtain good operability.

  In the present invention, it is preferable to design the braking energy to be larger than the driving energy because driving using only the energy recovered at the time of braking leads to improvement of the efficiency of the electric device. Therefore, it is preferable that the above-described drive gain table and braking gain table are set so that the braking gain is larger than the operation amount of the same turning operation lever.

  Next, in step S14, it is determined whether the relief pressure of the A port is lowered by the control of FIG. 7 and the A port pressure is higher than a preset threshold value P2. If this condition is satisfied, in step S15, a value TR is set as the electric motor torque command value T2 so that a decrease in torque of the swing hydraulic motor caused by lowering the relief pressure of the A port is generated by the swing electric motor. . (Torque command value T2 = TR)

  On the other hand, if it is determined in step S14 that the condition A port relief pressure is lowered and the A port pressure is higher than the threshold value P2, it is determined that the condition is not satisfied, step S16 is executed. It is determined whether the relief pressure of the B port is lowered by the control of 8 and the B port pressure is higher than a preset threshold value P2. When these conditions are satisfied, a value TR that causes the swing electric motor to generate a torque decrease by lowering the relief pressure of the B port is set to T2, and the electric motor torque command value is set to T2, as described above. Set. (Torque command value T2 = TR) Here, the torque command value T2 = TR becomes smaller when the A-port relief valve 28 or B-port relief valve 29 is controlled, and the torque command value T2 = TR becomes smaller by being lowered from a predetermined relief pressure of the swing hydraulic motor. The torque command value supplements the torque of the hydraulic motor. For example, it is a value calculated based on the reduction width of the relief pressure and the volume of the hydraulic motor.

  On the other hand, when it is determined whether the relief pressure of the B port is lowered and the B port pressure is higher than a preset threshold value P2, and it is determined that the condition is not satisfied, an electric motor torque command is determined in step S17. The value T2 = 0.

  Here, the threshold value P2 is set to a value slightly smaller than the relief pressure value set to be smaller than normal, for example, several MPa, and when the relief pressure of the port is lowered, the port pressure at any time point is compared with P2. By doing so, it can be judged whether the relief is performed at that time.

  Next, in step S18, the magnitudes of T1 and T2 of the swing electric torque command value obtained as described above are compared, and the larger electric motor torque command value is selected as the torque command value of the swing electric motor 25. . Then, the torque control value is used to control the power control unit 55 to generate a torque corresponding to the decrease in the swing hydraulic motor torque by the swing electric motor. As a result, a torque corresponding to the operation amount of the turning operation lever can be obtained by the total torque of the turning hydraulic motor 27 and the turning electric motor 25. Therefore, the operator can obtain a desired torque corresponding to the operation amount of the turning operation lever with respect to the turning body, and can obtain good operability.

  Further, as described above, in this embodiment, the swing operation lever position is in the neutral state and the maximum state, the hydraulic only mode in which the swing body is controlled by the swing hydraulic motor alone, and the swing operation lever position is in the intermediate range. And a combined turning mode in which braking and driving is performed by the total torque of the hydraulic motor and the turning electric motor. And it has the structure which switches each operation mode according to the amount of operation of a turning lever. Therefore, when the desired total torque corresponding to the amount of operation of the turning lever cannot be obtained in the combined turning mode, the acceleration / deceleration of the turning body generated according to the amount of operation of the turning operation lever may vary depending on the mode. . Due to this difference in acceleration / deceleration, the operator feels uncomfortable in operation. Therefore, the total torque of the swing hydraulic motor and the swing electric motor according to the operation amount of the swing operation lever can be obtained by braking / driving the swing electric motor based on the swing electric torque command value calculated in the present embodiment. . Therefore, the difference in the acceleration / deceleration of the revolving structure in each operation mode and the uncomfortable feeling of the operator due to this can be alleviated, and good operability can be realized.

  In addition, an operator accustomed to the operation of a construction machine such as a hydraulic excavator, which calculates and calculates a torque command value of the swing electric motor and brakes and drives the swing electric motor as in this embodiment, and is driven by a hydraulic motor alone. However, it is possible to perform an operation according to the operation amount of the turning operation lever without feeling uncomfortable due to the difference in the acceleration / deceleration speed of the turning body.

  In calculating the torque command value of the swing electric motor, after selecting the larger of the torque command values T1 and T2 in step S18, the torque command is set so that an excessive load is not applied to the swing mechanism 26 in step S19. The value may be limited so that the total torque of the swing hydraulic motor 27 and the swing electric motor 25 does not exceed the torque of the conventional hydraulic motor. Further, the rate of change of the torque command value may be limited so that the torque of the swing electric motor 25 changes suddenly so that the operator does not feel uncomfortable. Further, when drive torque is generated by the swing electric motor 25, the load of the engine is reduced by performing control to reduce the volume of the hydraulic pump 41 so as to reduce the work rate of the hydraulic pump 41 by the work rate. Can be reduced.

  FIG. 12 shows a system configuration diagram of main electric and hydraulic equipment of the excavator according to the second embodiment. In the first embodiment, the opening area of the bleed-off and meter-out of the control valve 42 is made larger than that of the conventional machine so that the driving and braking torque of the swing hydraulic motor 27 becomes smaller than that of the conventional machine. Instead, or in combination with it, the controller 80 may control the spool stroke of the control valve 42 so that the driving and braking torque of the swing hydraulic motor 27 can be made smaller than that of the conventional machine.

  For example, when the revolving structure is driven, when the spool stroke corresponding to a predetermined operation amount is S1 in the conventional construction machine as shown in FIG. 13, in the present invention, the spool stroke is controlled to be S2. To do. By doing so, the bleed-off opening area is increased and the drive torque of the swing hydraulic motor 27 is decreased. Further, when braking the revolving structure, when the spool stroke corresponding to a predetermined operation amount is S3 in the conventional construction machine as shown in FIG. 14, in the present invention, the spool stroke is controlled to be S4. To do. By doing so, the meter-out opening area is increased, and the braking torque of the swing hydraulic motor 27 is decreased. In this way, the same effect as that of the first embodiment can be obtained by performing the control for generating the torque by the swing electric motor 25 as much as the braking / driving torque of the swing hydraulic motor 27 is reduced.

  The present invention can be applied to all work / construction machines equipped with a swing body, and the application of the present invention is not limited to a hydraulic excavator. As described above, a combined swing of a hydraulic motor and an electric motor is possible. It is not necessary to have a mode and a hydraulic motor independent turning mode, and a switchable configuration.

10 Lower traveling body 11 Crawler 12 Crawler frame 13 Traveling hydraulic motor (right)
14 Traveling hydraulic motor (left)
20 slewing body 21 slewing frame 22 engine 23 assist generator motor 24 capacitor 25 slewing electric motor 26 slewing mechanism 27 slewing hydraulic motor 28 A port side relief valve 29 B port side relief valve 30 excavator mechanism 31 boom 32 boom cylinder 33 arm 34 arm cylinder 35 Bucket 36 Bucket Cylinder 40 Hydraulic System 41 Hydraulic Pump 42 Control Valve 43 Hydraulic Piping 44 Turning Spool 51 Chopper 52 Turning Electric Motor Inverter 53 Assist Electric Generator Motor Inverter 54 Smoothing Capacitor 55 Power Control Unit 72 Turning Operation Lever 75 Electric / Hydraulic Signal Conversion device 80 controller

Claims (2)

A swing hydraulic motor driven by hydraulic pressure generated by a hydraulic pump driven by an engine;
A swing electric motor connected to the swing hydraulic motor and driven by electric power from a power storage device;
A swivel body connected to the swivel electric motor,
Construction in which the swing electric motor and the swing hydraulic motor are controlled according to the operation amount of the swing operation lever for operating the swing body, and the swing body is controlled / controlled by the total torque of the swing electric motor and the swing hydraulic motor. In the machine
A relief valve for changing a relief pressure is provided between the hydraulic pump and the swing hydraulic motor,
Relief of the swing hydraulic motor when the absolute value of the rotation speed of the swing electric motor exceeds a preset first rotation speed or the operation amount of the swing operation lever exceeds a preset first operation amount. After that, the absolute value of the rotation speed of the swing electric motor is less than the second rotation speed set to the first rotation speed or less, or the operation amount of the swing operation lever is set to the first operation amount or less. A construction machine characterized by raising the lowered relief pressure of the swivel hydraulic motor when it falls below the second manipulated variable. The construction machine according to claim 1,
When the relief pressure of the swing hydraulic motor is reduced and the pressure of the swing hydraulic motor exceeds a preset pressure, the torque decrease of the swing hydraulic motor due to the reduction of the relief pressure of the swing hydraulic motor An electric motor torque command value that causes the swing electric motor to generate a motor is calculated.