JP5823932B2 - Hydraulic drive unit for construction machinery - Google Patents

Description

  The present invention relates to a hydraulic drive device for a construction machine, and more particularly to a hydraulic drive device that drives a revolving body of a construction machine.

  BACKGROUND ART A hydraulic drive device for a construction machine having a revolving body such as a hydraulic excavator includes a revolving motor unit that incorporates a revolving hydraulic motor that drives the revolving body. In the swing motor unit, in order to limit the pressure oil pressure supplied to the swing hydraulic motor or the pressure oil pressure discharged from the swing motor so as not to exceed a predetermined pressure, an oil path of the swing hydraulic motor is provided. Relief valves called swivel relief valves are provided.

  2. Description of the Related Art In a hydraulic drive device for a construction machine, there is known a hydraulic drive device that can change a set pressure (relief pressure) of a relief valve provided in each of a swing hydraulic motor oil passage (see, for example, Patent Document 1). By making the relief pressure of each relief valve changeable, the drive pressure or braking pressure of the swing hydraulic motor can be changed, and the maximum drive torque or brake torque of the swing hydraulic motor can be changed. In the technique described in Patent Document 1, by changing the set pressure of each relief valve according to the attitude of the front work machine, the swing hydraulic motor of the swing hydraulic motor is changed according to the change in the inertial mass of the swing body that changes according to the attitude of the front work machine. The maximum driving torque or braking torque is changed to improve the operability.

JP-A-6-173299

  If the set pressure (relief pressure) of each relief valve of the swing hydraulic motor can be changed in the hydraulic drive device of the construction machine as described in Patent Document 1, the maximum drive torque or braking torque of the swing hydraulic motor is changed. The effect is obtained.

  However, in such a hydraulic drive device, for example, if a component such as each relief valve breaks down and the relief pressure remains switched to the low pressure side, the braking torque and the maximum drive torque of the swing hydraulic motor will decrease. This makes it difficult to ensure the safe operation of the revolving structure. On the other hand, if the relief pressure remains switched to the high pressure side, safety can be ensured, but a shock may occur at the start and stop of turning when the inertial mass of the turning body is small, and operability may deteriorate. There is. As described above, in the hydraulic drive device in which the relief pressure in the conventional relief valve is variable, when a component such as the relief valve breaks down, it becomes difficult to ensure the safe operation of the swivel body until it is repaired. There was a problem that the sex deteriorated.

  The present invention has been made based on the above-described matters, and in a hydraulic drive device capable of changing the drive torque or braking torque of a swing hydraulic motor, even if a failure occurs in its components, the swing hydraulic motor It is an object of the present invention to provide a highly safe hydraulic drive device for a construction machine that can avoid an unintended decrease in the driving torque or braking torque.

  To achieve the above object, according to a first aspect of the present invention, there is provided a hydraulic drive device for a construction machine including a swing body, a working machine, and a swing operation lever for operating the swing body. A swing hydraulic motor that drives or brakes the swivel body with discharged pressure oil, a swing direction control valve that controls a flow of pressure oil supplied from the hydraulic pump to the swing hydraulic motor, and the swing direction control valve A first swing relief valve that is provided in one and other oil passages that connect the swing hydraulic motor and the swing hydraulic motor, and that restricts the drive pressure or braking pressure of the swing hydraulic motor to be equal to or lower than a first set pressure, A second set pressure that is provided in each oil passage and whose driving pressure or braking pressure of the swing hydraulic motor is lower than the first set pressure by the pilot pressure oil supplied to the operation section. A second swivel relief valve that can be switched to the bottom, and an oil passage on the upstream side of the second swivel relief valve. A switching valve for communicating / blocking the swing relief valve, an electromagnetic valve for generating pilot pressure oil to be supplied to the operation section of the switching valve and the operation section of the second swing relief valve, and an operation for driving the solenoid valve And a control unit for outputting a signal.

  In addition, a second invention further includes a pipe line for supplying a pilot primary pressure from a pilot pressure source to the electromagnetic valve, and an electromagnetic switching valve for switching communication / blocking of the pipe line in the first invention, The control unit includes a controller that executes a control operation, a solenoid valve driver that generates a control signal for driving the solenoid valve based on a command signal from the controller, and the command signal is output from the controller to the solenoid valve driver. And an electromagnetic switching valve driving circuit for driving the electromagnetic switching valve to bring the pipe into a communicating state only when the electromagnetic switching valve is driven.

  Furthermore, a third invention is the second pressure sensor according to the second invention, wherein the first pressure sensor detects a pilot pressure when the turning operation lever is operated, and the second pressure sensor detects a driving pressure or a braking pressure of the turning hydraulic motor. And the controller takes in the pilot pressure during operation of the swing operation lever from the first pressure sensor and the driving pressure or braking pressure of the swing hydraulic motor from the second pressure sensor, and these pressures. The command signal is output in response to the signal.

  According to a fourth aspect, in the second or third aspect, the controller outputs the control signal when the driving torque or braking torque of the swing hydraulic motor is decreased.

  Furthermore, a fifth invention is characterized in that in any one of the second to fourth inventions, the electromagnetic switching valve driving circuit includes a diode unit and a relay.

  According to the present invention, it is possible to provide a highly safe hydraulic drive device for a construction machine that can avoid an unintended decrease in drive torque or braking torque of a swing hydraulic motor even when a failure occurs in its constituent parts. Can do.

1 is a side view of a hybrid hydraulic excavator provided with an embodiment of a hydraulic drive device for a construction machine according to the present invention. It is a circuit diagram which shows the structure of one Embodiment of the hydraulic drive apparatus of the construction machine of this invention. It is a block diagram which shows the processing content of the controller which comprises one Embodiment of the hydraulic drive apparatus of the construction machine of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking a hybrid hydraulic excavator as an example of a construction machine. Note that the present invention can be applied to all construction machines (including work machines) including a rotating body, and the application of the present invention is not limited to a hybrid hydraulic excavator. For example, the present invention can also be applied to a crane vehicle having a swivel body. FIG. 1 is a side view of a hybrid hydraulic excavator provided with an embodiment of a hydraulic drive device for a construction machine according to the present invention.

  In FIG. 1, the hydraulic excavator includes a traveling body 10, a swiveling body 20 provided on the traveling body 10 so as to be able to swivel, and an articulated work machine 30 installed on the revolving body 20.

  The traveling body 10 includes a pair of crawlers 11a and 11b and crawler frames 12a and 12b (only one side is shown in FIG. 1), a pair of traveling hydraulic motors 13 and 14 that independently drive and control the crawlers 11a and 11b, and It consists of a speed reduction mechanism.

  The swing body 20 includes a swing frame 21, an engine 22 as a prime mover provided on the swing frame 21, an assist power generation motor 23 driven by the engine 22, a swing electric motor 25, an assist power generation motor 23, and a swing. The traveling body 10 includes an electric double layer capacitor 24 electrically connected to the electric motor 25 and a speed reduction mechanism that decelerates the rotation of the swing electric motor 25, and the total torque of the swing electric motor 25 and the swing hydraulic motor 27. The revolving mechanism 20 is configured to revolve the revolving body 20 (the revolving frame 21).

  In addition, a work machine 30 is mounted on the revolving unit 20. The work machine 30 includes a boom 31 provided on the revolving frame 21 of the revolving structure 20 so as to be able to move up and down, a boom cylinder 32 for driving the boom 31, and an arm rotatably supported near the tip of the boom 31. 33, an arm cylinder 34 for driving the arm 33, a bucket 35 rotatably supported at the tip of the arm 33, a bucket cylinder 36 for driving the bucket 35, and the like.

  Furthermore, a hydraulic pump that generates hydraulic pressure for driving hydraulic actuators such as the above-described traveling hydraulic motors 13 and 14, boom cylinder 32, arm cylinder 34, bucket cylinder 36, etc. And a hydraulic system 40 including a control valve for driving and controlling each hydraulic actuator.

  Next, the configuration of the hydraulic drive apparatus will be schematically described with reference to FIG. FIG. 2 is a circuit diagram showing a configuration of an embodiment of a hydraulic drive device for a construction machine according to the present invention. In the embodiment shown in FIG. 2, only the drive system related to the swing hydraulic motor 27 that drives the swing body 20 is shown.

  The hydraulic drive device includes an engine 22 as a prime mover, a variable displacement hydraulic pump 1 driven by the engine 22, a hydraulic oil tank 2, an operation lever device 3 for instructing the operation of the swing body 20, and a hydraulic pump. 1 includes a turning direction control valve 4 for controlling the flow of pressure oil supplied from 1 to the turning hydraulic motor 27, and a turning hydraulic motor 27 that is driven by the pressure oil discharged from the hydraulic pump 1 to rotate the turning body 20. Slewing motor unit 5, control unit 6, pilot pressure source 7, electromagnetic switching valve 8 for switching the supply / shutoff of pilot pressure oil from pilot pressure source 7 to slewing motor unit 5, and pilot pressure source 7 And an electromagnetic proportional pressure reducing valve unit 9 that generates a driving pressure for a switching valve, which will be described later, based on the pilot pressure oil.

  Pressure receiving portions 41b and 41c are provided at both ends of the turning direction control valve 4, and the operating pilot pressure from the operating lever device 3 is guided to one of the pressure receiving portions 41b and 41c, and the turning direction control valve 4 is caused by this operating pilot pressure. Switching operation is performed. When the main spool 41a of the turning direction control valve 4 is switched from the neutral position shown to the left A position shown in the drawing, the pressure oil from the hydraulic pump 1 is pumped in the oil passage 43 and the meter-in throttle at the A position of the turning direction control valve 4. The swivel motor unit 5 is supplied via the actuator oil passage 44a. The return oil from the turning motor unit 5 is returned to the tank 2 via the actuator oil passage 44b, the meter-out throttle at the position A of the turning direction control valve 4, and the discharge oil passage 45. Here, pressure sensors 49a and 49b for detecting the pressure of the pressure oil supplied to the respective oil passages are provided in the actuator oil passages 44a and 44b. The pressure signals of the oil passages detected by the pressure sensors 49 a and 49 b are output to the controller 65 of the control unit 6.

  The turning direction control valve 4 is a center bypass type valve, and is arranged on the center bypass oil passage 46 connected to the pump oil passage 43 on the upstream side and connected to the discharge oil passage 45 on the downstream side. When the main spool 41a is in the neutral position shown in the figure, the turning direction control valve 4 opens the center bypass oil passage 46 and circulates the entire amount of oil discharged from the hydraulic pump 1 to the tank 2 via the discharge oil passage 45. . When the main spool 41a of the turning direction control valve 4 is switched from the neutral position shown in the drawing to either the right or left shown in the drawing, the center bypass oil passage 46 is throttled in accordance with the switching stroke, and the pressure in the pump oil passage 43 ( The discharge pressure of the hydraulic pump 1 is increased and the oil discharged from the hydraulic pump 1 is supplied to the swing motor unit 5 via the swing direction control valve 4 due to this pressure increase. When the turning direction control valve 4 is switched at full stroke, the center bypass oil passage 46 is completely closed, and the entire amount of oil discharged from the hydraulic pump 1 is supplied to the turning motor unit 5.

  The swing motor unit 5 has a motor housing 51, and components of the swing hydraulic motor 27 (for example, a swash plate and a piston) are disposed in the motor housing 51. In the motor housing 51, a pair of actuator oil passages 52a, 52b and a discharge oil passage 53 connected to the pair of actuator oil passages 44a, 44b are formed, and a pair of first swing relief valves 54a. , 54b and a pair of first check valves 55a, 55b for replenishment. Further, the turning hydraulic motor 27 has two ports that serve as an inlet and an outlet for hydraulic oil. In this embodiment, the port that serves as the inlet for the hydraulic oil when turning left is used as an A port in the actuator oil passage 52a. Connected to the actuator oil passage 52b with the port serving as the outlet as B port. Outside the motor housing 51 in the swing motor unit 5 is provided with an operating portion that receives a pilot pressure from an electromagnetic proportional pressure reducing valve unit 9 described later, and a second swing relief valve that makes the relief set pressure variable according to the pilot pressure. 56a, 56b, a pair of second check valves 57a, 57b for replenishment, and switching valves 58a, 58b are arranged.

  Each of the pair of first swing relief valves 54 a and 54 b has an upstream side connected to the pair of actuator oil passages 52 a and 52 b and a downstream side (discharge side) connected to the discharge oil passage 53. The pair of first swing relief valves 54a and 54b has a function of limiting the pressure of the actuator oil passages 52a and 52b so as not to exceed the first set pressure.

  Here, the pressure of the actuator oil passages 52a and 52b restricted by the first swing relief valves 54a and 54b is driven by the hydraulic oil supplied from the hydraulic pump 1 to the swing hydraulic motor 27 when the swing body 20 is activated. When the swing body 20 is driven, this is the upper limit value of the driving pressure. When the swing body 20 is decelerated or stopped, the swing hydraulic motor 27 is driven inertially by the swing body 20, and the pump action of the swing hydraulic motor 27 is used. When braking pressure (back pressure) is generated in the discharge-side actuator oil passage 52a or 52b, this is the upper limit value of the braking pressure.

  The pair of first check valves 55a and 55b for replenishment are connected to the pair of actuator oil passages 52a and 52b on the downstream side and to the discharge oil passage 53 on the upstream side, respectively. The first check valves 55a and 55b for replenishment are actuators on the suction side of the swing hydraulic motor 27 by the pump action of the swing hydraulic motor 27 when the swing hydraulic motor 27 is driven by the swing body 20 when the swing body 20 is stopped. When the oil passage 52a or 52b is about to become negative pressure, the actuator oil passage 52a or 52b is supplied with pressure oil from the discharge oil passage 53 on the downstream side of the first swing relief valves 54a and 54b to prevent cavitation. To do.

  Similarly to the pair of first swing relief valves 54a and 54b, the second swing relief valves 56a and 56b are connected to the pair of actuator oil passages 52a and 52b, respectively, and the downstream side (discharge side) is discharged oil. It is connected to the path 53. In other words, the second swing relief valves 56a and 56b are connected in parallel to the pair of actuator oil passages 52a and 52b with respect to the pair of first swing relief valves 54a and 54b, and the second swing relief valves 56a and 56b. On the downstream side of 56b, the oil discharged from the second swing relief valves 56a and 56b is joined to the oil discharged from the first swing relief valves 54a and 54b at a position near the downstream of the first swing relief valves 54a and 54b. It is connected to the drain oil passage 53 on the downstream side of the one-turn relief valves 54a, 54b.

  In the second swing relief valves 56a and 56b, the pressure of the actuator oil passages 52a and 52b (the driving pressure or the braking pressure of the swing hydraulic motor 27) corresponds to the first pressure according to the operation pressure oil supplied from the electromagnetic proportional pressure reducing valve unit 9. It has a function of limiting so as not to exceed a second set pressure lower than the set pressure. Specifically, when the pilot pressure from the electromagnetic proportional pressure reducing valve unit 9 is input to each operation unit, each relief pressure is set to a second set pressure lower than the first set pressure, and the pilot pressure is set. Is not input to each operation unit, the pressure is set to be equal to or higher than the first set pressure.

  Similarly to the first check valves 55a and 55b, the pair of second check valves 57a and 57b for replenishment is connected to the pair of actuator oil passages 52a and 52b on the downstream side, and the discharge oil passage 53 on the upstream side, respectively. It is connected.

  The switching valves 58a and 58b are respectively arranged on the upstream side of the second swing relief valves 56a and 56b, and switch the open / close position according to an operation signal from the electromagnetic proportional pressure reducing valve unit 9. Specifically, when the pilot pressure from the electromagnetic proportional pressure reducing valve unit 9 is input to each operation unit, the operation position is switched to the open position (communication position), and the pilot pressure is not input to each operation unit. Is switched to the closed position (blocking position).

  When the switching valves 58a and 58b are in the illustrated closed positions, respectively, the communication between the pair of actuator oil passages 52a and 52b and the second swing relief valves 56a and 56b is blocked, and the second swing relief valves 56a and 56b. Disable the function. At this time, the pair of first swing relief valves 54a and 54b function independently, and the relief characteristics of the first swing relief valve are effective as they are. When the switching valves 58a and 58b are switched from the illustrated closed position to the open position, the actuator oil passages 52a and 52b communicate with the second swing relief valves 56a and 56b, respectively, and the second swing relief valves 56a and 56b. Each function is enabled. Specifically, a relief characteristic with a set pressure lower than the relief characteristic of the first swing relief valve can be obtained.

  Thus, the first relief in which the pair of first swing relief valves 54a and 54b function independently by switching the opening and closing of the switching valves 58a and 58b and the function of the second swing relief valves 56a and 56b at the same time. One of the second relief mode in which the mode functions in combination with one of the pair of first swing relief valves 54a and 54b and the second swing relief valves 56a and 56b can be selected.

Next, a pilot pressure oil system for controlling the switching valves 58a and 58b and the second swing relief valves 56a and 56b will be described.
The pilot pressure source 7 is configured by, for example, a pilot pressure pump driven by the engine 22. A pilot pipe line 71 from the pilot pressure source 7 branches in two directions, one of which is connected to the operation lever device 3 and the other is an electromagnetic switching valve for switching supply / cutoff of pilot pressure oil to the swing motor unit 5. 8 is connected.

  The operation lever device 3 is provided with a pair of pressure reducing valves (not shown) that generate pilot pressure corresponding to the operation amount and operation direction of the operation lever. The primary port side of the pair of pressure reducing valves is connected to one pilot pipe line 71. The secondary port on one side of the pair of pressure reducing valves is connected to the pressure receiving portion 41c of the turning direction control valve 4 via the pilot line 72a, and the secondary port of the pressure reducing valve on the other side is connected to the pilot line 72b. And connected to the pressure receiving portion 41 b of the turning direction control valve 4. Here, pressure sensors 77a and 77b for detecting the operating pressure of the operating lever device 3 are provided in the pilot pipe lines 72a and 72b. The pressure sensor 77a detects the pilot pressure when the control lever device 3 is turned left, and the pressure sensor 77b detects the pilot pressure when the control lever device 3 is turned right. The detected pilot pressure signal of the operating lever device 3 is output to the controller 65 of the control unit 6.

  The other pilot pipeline 71 is branched into two pilot pipelines 71 a and 71 b on the downstream side via the electromagnetic switching valve 8. The pilot pipelines 71a and 71b are connected to two input ports of the electromagnetic proportional pressure reducing valve unit 9, respectively.

  The electromagnetic switching valve 8 is a 3-port 2-position electromagnetic switching valve having a spring 8b on one end side and an electromagnetic operation portion 8a on the other end side, and depending on the presence or absence of a voltage signal to the electromagnetic operation portion 8a, Change the spool position. When a voltage signal is applied to the electromagnetic operating unit 8a, the spool position is set to supply the pressure oil from the pilot hydraulic power source 7 to the electromagnetic proportional pressure reducing valve unit 9 via the pilot pipe lines 71a and 71b. When the voltage signal to 8a is removed, the supply of the pressure oil from the pilot hydraulic power source 7 is cut off, and the spool position is set to discharge the pressure oil from the pilot pipe lines 71a and 71b to the tank 2. An electric signal is supplied from the battery 69 to the electromagnetic operation unit 8a through a contact point of a relay 68 constituting the control unit 6 described later.

  The electromagnetic proportional pressure reducing valve unit 9 depressurizes the pressure oil from the pilot pressure source 7, and generates a drive pressure for one switching valve 58a and one second swing relief valve 56a, and a first electromagnetic proportional pressure reducing valve 9A. There is provided a second electromagnetic proportional pressure reducing valve 9B for reducing the pressure oil from the pilot pressure source 7 and generating a driving pressure for the other switching valve 58b and the other second turning relief valve 56b.

  The first electromagnetic proportional pressure reducing valve 9A is a 3-port 2-position electromagnetic proportional valve, and has a spring 9Ab on one end side and an electromagnetic operation part 9Aa on the other end side, and is applied to the electromagnetic operation part 9Aa. The spool position is continuously switched by a signal. When a PWM signal is applied to the electromagnetic operation unit 9Aa, the pressure oil supplied to the input port is supplied from the output port via the pilot line 73a to the operation unit of one switching valve 58a and one second swing relief valve. The spool position is supplied to the operation unit 56a. When the PWM signal to the electromagnetic operation unit 9Aa is removed, the supply of the pressure oil from the pilot hydraulic power source 7 is cut off, and the spool position for discharging the pressure oil from the pilot pipe line 73a to the tank 2 is obtained. The electromagnetic operation unit 9Aa is supplied with a PWM signal from an electromagnetic valve driver unit 66 constituting a control unit 6 described later.

  The second electromagnetic proportional pressure reducing valve 9B is a three-port, two-position electromagnetic proportional valve having a spring 9Bb on one end side and an electromagnetic operation portion 9Ba on the other end side, and is applied to the electromagnetic operation portion 9Ba. The spool position is continuously switched by a signal. When a PWM signal is applied to the electromagnetic operation unit 9Ba, the pressure oil supplied to the input port is supplied from the output port through the pilot line 73b to the operation unit of the other switching valve 58b and the other second swing relief valve. The spool position is supplied to the operation unit 56b. When the PWM signal to the electromagnetic operation unit 9Ba is removed, the supply of the pressure oil from the pilot hydraulic power source 7 is shut off, and the spool position is set to discharge the pressure oil from the pilot pipe line 73b to the tank 2. The electromagnetic operation unit 9Ba is supplied with a PWM signal from an electromagnetic valve driver unit 66 constituting a control unit 6 described later.

  The control unit 6 includes a controller 65, a solenoid valve driver unit 66, a diode unit 67, and a relay 68. The battery 69 sends the stored power to the control unit 6.

  The electromagnetic valve driver unit 66 receives a first command signal from the controller 65 and generates a PWM signal to be sent to the electromagnetic operation unit 9Aa of the first electromagnetic proportional pressure reducing valve 9A. And a second electromagnetic valve driver 66b for generating a PWM signal to be sent to the electromagnetic operation part 9Ba of the second electromagnetic proportional pressure reducing valve 9B.

  The diode unit 67 includes a first diode 67a in which the first command signal output terminal of the controller 65 and its anode terminal are connected by a cable, and its cathode terminal and one end side of the coil of the relay 68 are connected by a cable. The second command signal output terminal and its anode terminal are connected by a cable, and a second diode 67b is connected by connecting the cathode terminal and one end side of the coil of the relay 68 by a cable.

  The relay 68 has one end connected to the cathode terminals of the first and second diodes 67a and 67b, the other end connected to the negative electrode of the battery 69, and one end connected to the positive electrode of the battery 69. The other end side is provided with A contact which connected to the electromagnetic operation part 8a of the electromagnetic switching valve 8. FIG.

  The controller 65 takes in the operation pilot pressure signal of the operation lever device 3 detected by the pressure sensors 77a and 77b and the pressure signal of each oil passage detected by the pressure sensors 49a and 49b, and drives the electromagnetic proportional pressure reducing valve unit 9. A mode selection command to the solenoid valve driver unit 66 is calculated and output. In the present embodiment, when the swing body 20 is driven to turn, the first and second swing relief valves 54a and 54b are made effective as they are so that a high drive torque of the swing hydraulic motor 27 can be obtained. The second command signal is not output.

  On the other hand, at the time of turning braking of the revolving structure 20, the braking torque of the turning hydraulic motor 27 is decreased, and the decrease in the braking torque is compensated by increasing the regenerative energy of the turning electric motor 25. For this reason, the controller 65 outputs a first or second command signal in order to obtain a relief characteristic that has decreased to the second set pressure of the second swing relief valves 56a and 56b.

  Next, control of the controller 65 in the present embodiment will be described with reference to FIG. FIG. 3 is a block diagram showing the processing contents of the controller constituting one embodiment of the hydraulic drive device for the construction machine of the present invention. In FIG. 3, the same reference numerals as those shown in FIGS. 1 and 2 are the same parts, and detailed description thereof is omitted.

  The controller 65 shown in FIG. 3 includes a controller unit that includes a calculation unit that calculates a command signal based on an input signal and a storage unit that stores a set value in advance. As shown in FIG. 3, the controller 65 receives pressure signals from the pressure sensors 77a, 77b, 49a, and 49b. The controller 65 outputs the calculated command signal to the solenoid valve driver unit 66 and the diode unit 67, respectively.

  In the arithmetic unit, comparison arithmetic units 101a, b, 102a, b, 103a, b to which pressure signals from the pressure sensors 77a, 77b, 49a, 49b are respectively input, logical sum arithmetic units 104a, 104b, and logical products And computing units 105a and 105b.

  The comparison computing unit 101a receives the pilot pressure when the control lever device 3 is turned to the left detected by the pressure sensor 77a, and outputs a digital output signal 1 when this signal is higher than a preset value. This output signal is input to one input terminal of the logical sum calculator 104a. Further, the comparison arithmetic unit 103a receives the pilot pressure when the control lever device 3 is turned counterclockwise, and outputs the digital output signal 1 only when this signal is lower than a preset value. This output signal is input to one input terminal of the AND operator 105a.

  The comparator 102b receives the B port pressure of the swing hydraulic motor 27 detected by the pressure sensor 49b, and outputs a digital output signal 1 when this signal is higher than a preset value. This output signal is input to the other input terminal of the logical sum calculator 104a. The output of the logical sum operator 104a is input to one input terminal of the logical product operator 105b.

  The comparison computing unit 101b receives the pilot pressure when the control lever device 3 turns right, which is detected by the pressure sensor 77b, and outputs a digital output signal 1 when this signal is higher than a preset value. This output signal is input to the other input terminal of the logical sum calculator 104b. The comparator 103b receives the pilot pressure when the control lever device 3 turns right, and outputs the digital output signal 1 only when this signal is lower than a preset value. This output signal is input to the other input terminal of the AND operator 105b.

  The comparator 102a receives the A port pressure of the swing hydraulic motor 27 detected by the pressure sensor 49a, and outputs a digital output signal 1 when this signal is higher than a preset value. This output signal is input to one input terminal of the logical sum calculator 104b. The output of the logical sum operator 104b is input to the other input terminal of the logical product operator 105a.

  The output of the AND operator 105b is output to the second electromagnetic valve driver 66b and the second diode 67b as the second command signal of the controller 65. The output of the AND operator 105a is output to the first solenoid valve driver 66a and the first diode 67a as the first command signal of the controller 65.

Next, the operation in the present embodiment will be described with reference to FIGS.
First, in FIG. 3, when both the outputs of the logical product calculators 105a and 105b are zero, no signal is output from the controller 65 to the solenoid valve driver unit 66 and the diode unit 67 in FIG. For this reason, the diode unit 67 becomes inoperative, the relay 68 is not excited, and the power of the battery 69 is not supplied to the electromagnetic operation unit 8a of the electromagnetic switching valve 8. In addition, the electromagnetic valve driver unit 66 is also inoperative, and no PWM signal is supplied to the electromagnetic operating portions 9Aa and 9Ba of the electromagnetic proportional pressure reducing valve unit 9.

  As a result, the pressure oil from the pilot hydraulic power source 7 is blocked by the electromagnetic switching valve 8 and is not supplied to the electromagnetic proportional pressure reducing valve unit 9. As a result, the pair of switching valves 58a and 58b are in the illustrated closed position, and the relief pressure of the second swing relief valves 56a and 56b is set to be equal to or higher than the first set pressure. Accordingly, at this time, the pair of first swing relief valves 54a and 54b function independently, and the first relief mode in which the relief characteristics of the first swing relief valve are valid as they are is selected. In the swing motor unit 5, A high driving torque and a high braking torque can be obtained.

  Next, for example, when the operator performs a left turn operation of the operation lever device 3 or when the meter-out pressure (B port pressure of the turning hydraulic motor 27) at the left turn is equal to or higher than a set pressure, FIG. The left turn pilot pressure signal detected by the pressure sensor 77a is input to the comparison calculator 101a, or the B port pressure of the swing hydraulic motor 27 detected by the pressure sensor 49b is input to the comparison calculator 102b, and the OR calculator 104a. One condition of the AND operator 105b is configured via Here, if the right-turn pilot pressure signal detected by the pressure sensor 77b from the comparison calculator 103b is almost zero, the output of the AND calculator 105b is used as the second command signal of the controller 65, and the second solenoid valve driver 66b and the second diode 67b.

In FIG. 2, a signal is applied to the anode terminal of the second diode 67b of the diode unit 67, and the relay 68 is excited via the cathode terminal. As a result, the contact A of the relay 68 is operated, and an electric signal is supplied from the battery 69 to the electromagnetic operating portion 8 a of the electromagnetic switching valve 8. As a result, the electromagnetic switching valve 8 switches the spool position and supplies the pressure oil from the pilot hydraulic power source 7 to the electromagnetic proportional pressure reducing valve unit 9 via the pilot pipe lines 71a and 71b. Since the signal is applied to the second electromagnetic valve driver 66b, the second electromagnetic valve driver 66b supplies the PWM signal to the electromagnetic operation unit 9Ba of the second electromagnetic proportional pressure reducing valve 9B. As a result, the second electromagnetic proportional pressure reducing valve 9B switches the spool position, and sends the pilot pressure oil supplied to the input port from the output port via the pilot line 73b to the operating portion of the other switching valve 58b and the other second pressure valve. It supplies to the operation part of the turning relief valve 56b.

  Since the other switching valve 58b is switched from the illustrated closed position to the open position, the actuator oil passage 52b communicates with the other second turning relief valve 56b, and the function of the other second turning relief valve 56b is made effective. To do. At this time, the relief characteristic of the other first turning relief valve 54b and the relief characteristic of the other second turning relief valve 56b function in combination. Specifically, a relief characteristic with a set pressure lower than the relief characteristic of the first swing relief valve is obtained, and the braking torque is reduced in the swing motor unit 5. On the other hand, when the electric motor of the swing electric motor 25 compensates for the reduced braking torque, the swing body 20 is properly braked and the regenerative energy can be increased.

  The pressure oil relieved by the first turning relief valve 54 a or 54 b and the other second turning relief valve 56 b returns to the hydraulic oil tank 2 through the discharge oil passage 53 in the turning motor unit 5.

  In the present embodiment configured as described above, the controller 65 determines whether to change the turning braking torque and switches the setting of the relief pressure, so that the turning operability is improved.

Next, in the hydraulic drive device according to the present embodiment, an operation when a failure occurs for each component will be described.
<When the second turning relief valve 56a or 56b is fixed to the low pressure side>
Even in such a case, when the controller 65 determines that the turning braking torque need not be changed, the switching valve 58a via the electromagnetic valve driver unit 66 and the first or second electromagnetic proportional pressure reducing valve 9A, 9B, or The second swing relief valve 56a or 56b and the A port or B port of the swing hydraulic motor 27 are blocked by 58b. As a result, in the swing motor unit 5, the relief characteristic (high pressure side) of the first swing relief valve in which the first swing relief valves 54a and 54b function independently becomes effective as it is.

  On the other hand, when the controller 65 determines that the turning braking torque is to be changed and a command to change the relief pressure setting (command to change to the relief characteristic on the low pressure side) is output, the solenoid valve driver unit 66 and Since the switching valve 58a or 58b operates in the communication direction via the first or second electromagnetic proportional pressure reducing valve 9A or 9B, the second swing relief valve 56a or 56b and the A port or B of the swing hydraulic motor 27 The port communicates. As a result, in the swing motor unit 5, the relief characteristic (low pressure side) of the second swing relief valve in which the second swing relief valve 56a or 56b functions is effective.

  In this way, even if the second swing relief valve 56a or 56b is fixed to the low pressure side, an unintended decrease in the braking torque of the swing hydraulic motor 27 can be avoided.

<When the switching valve 58a or 58b is fixed to the communication position>
Even in such a case, if the controller 65 determines that the turning braking torque does not need to be changed, the first or second electromagnetic proportional pressure reducing valve 9A, 9B is moved to the operating portion of the second turning relief valve 56a or 56b. Since the pilot pressure oil is not supplied, the relief pressures of the second swing relief valves 56a and 56b are set to be equal to or higher than the first set pressure. Accordingly, at this time, the pair of first swing relief valves 54a and 54b function independently, and the first relief mode in which the relief characteristics of the first swing relief valve are valid as they are is selected. In the swing motor unit 5, A high driving torque and a high braking torque can be obtained.

  On the other hand, when the controller 65 determines that the turning braking torque is to be changed and a command to change the relief pressure setting (command to change to the relief characteristic on the low pressure side) is output, the solenoid valve driver unit 66 and Since the pilot pressure oil is supplied to the operation portion of the second swing relief valve 56a or 56b via the first or second electromagnetic proportional pressure reducing valve 9A or 9B, each relief pressure is lower than the first set pressure. Set to the second set pressure. As a result, in the swing motor unit 5, the relief characteristic (low pressure side) of the second swing relief valve in which the second swing relief valve 56a or 56b functions is effective.

  Thus, even when the switching valve 58a or 58b is fixed at the communication position, an unintended decrease in the braking torque of the swing hydraulic motor 27 can be avoided.

<When the first and second electromagnetic proportional pressure reducing valves 9A and 9B are fixed to the command pressure generation side>
Even in such a case, when the controller 65 determines that the turning braking torque does not need to be changed, the electric signal of the battery 69 via the diode unit 67, the relay 68, and the contact is transmitted to the electromagnetic operation unit of the electromagnetic switching valve 8. 8a is not supplied. For this reason, the pressure oil from the pilot hydraulic power source 7 is not supplied to the electromagnetic proportional pressure reducing valve unit 9, and the pilot pressure oil is not supplied to the operation parts of the switching valves 58a and 58b and the second swing relief valves 56a and 56b. Accordingly, at this time, the pair of first swing relief valves 54a and 54b function independently, and the first relief mode in which the relief characteristics of the first swing relief valve are valid as they are is selected. In the swing motor unit 5, A high driving torque and a high braking torque can be obtained.

  On the other hand, when it is determined from the controller 65 that the turning braking torque is to be changed and a command for changing the relief pressure setting (command for changing to the relief characteristic on the low pressure side) is output, the diode unit 67 and the relay 68 are output. The electric signal of the battery 69 via the contact point is supplied to the electromagnetic operation part 8 a of the electromagnetic switching valve 8. Thus, the electromagnetic switching valve 8 switches the spool position and supplies the pressure oil from the pilot hydraulic power source 7 to the electromagnetic proportional pressure reducing valve unit 9 via the pilot pipe lines 71a and 71b. Since the pilot pressure oil is supplied to the operation portion of the switching valve 58a or 58b and the operation portion of the second swing relief valve 56a or 56b, each relief pressure is set to a second setting lower than the first set pressure. Set to pressure. As a result, in the swing motor unit 5, the relief characteristic (low pressure side) of the second swing relief valve in which the second swing relief valve 56a or 56b functions is effective.

  Thus, even when the first and second electromagnetic proportional pressure reducing valves 9A and 9B are fixed to the command pressure generation side, an unintended decrease in the braking torque of the swing hydraulic motor 27 can be avoided.

<When solenoid valve driver 66 continues output regardless of input>
Even in such a case, when the controller 65 determines that the turning braking torque does not need to be changed, the electric signal of the battery 69 via the diode unit 67, the relay 68, and the contact is transmitted to the electromagnetic operation unit of the electromagnetic switching valve 8. 8a is not supplied. For this reason, the pressure oil from the pilot hydraulic power source 7 is not supplied to the electromagnetic proportional pressure reducing valve unit 9, and the pilot pressure oil is not supplied to the operation parts of the switching valves 58a and 58b and the second swing relief valves 56a and 56b. Accordingly, at this time, the pair of first swing relief valves 54a and 54b function independently, and the first relief mode in which the relief characteristics of the first swing relief valve are valid as they are is selected. In the swing motor unit 5, A high driving torque and a high braking torque can be obtained.

  On the other hand, when it is determined from the controller 65 that the turning braking torque is to be changed and a command for changing the relief pressure setting (command for changing to the relief characteristic on the low pressure side) is output, the diode unit 67 and the relay 68 are output. The electric signal of the battery 69 via the contact point is supplied to the electromagnetic operation part 8 a of the electromagnetic switching valve 8. Thus, the electromagnetic switching valve 8 switches the spool position and supplies the pressure oil from the pilot hydraulic power source 7 to the electromagnetic proportional pressure reducing valve unit 9 via the pilot pipe lines 71a and 71b. Since the pilot pressure oil is supplied to the operation portion of the switching valve 58a or 58b and the operation portion of the second swing relief valve 56a or 56b, each relief pressure is set to a second setting lower than the first set pressure. Set to pressure. As a result, in the swing motor unit 5, the relief characteristic (low pressure side) of the second swing relief valve in which the second swing relief valve 56a or 56b functions is effective.

  Thus, even when the solenoid valve driver 66 continues to output regardless of the input, an unintended decrease in the braking torque of the swing hydraulic motor 27 can be avoided.

  According to the above-described embodiment of the hydraulic drive device for a construction machine according to the present invention, even if a failure occurs in the component parts, an unintended decrease in the drive torque or braking torque of the swing hydraulic motor 27 is avoided. It is possible to provide a hydraulic drive device for a construction machine with high safety.

  In the present embodiment, the operation parts of the switching valves 58a and 58b and the second swing relief valves 56a and 56b provided in the swing motor unit 5 are respectively connected via the first and second electromagnetic proportional pressure reducing valves 9A and 9B. The case where pilot pressure oil is supplied has been described as an example, but the present invention is not limited to this. For example, the pilot pressure oil may be supplied via an electromagnetic valve such as an electromagnetic opening / closing valve.

  In the present embodiment, the hydraulic drive device in the hybrid construction machine has been described as an example, but the present invention is not limited to this. As long as the driving torque or the braking torque is variable, the present invention can be applied to any hydraulic driving device.

DESCRIPTION OF SYMBOLS 1 Hydraulic pump 2 Hydraulic oil tank 3 Operation lever apparatus 4 Turning direction control valve 5 Swing motor unit 6 Control unit 7 Pilot pressure source 8 Electromagnetic switching valve 9 Electromagnetic proportional pressure reducing valve unit 9A 1st electromagnetic proportional pressure reducing valve 9B 2nd electromagnetic proportional pressure reducing Valve 20 Swing body 22 Engine 25 Swing electric motor 27 Swing hydraulic motor 44a, b Actuator oil path (oil path)
49a, b Pressure sensor (second pressure sensor)
52a, b Actuator oil passage (oil passage)
54a, b first swing relief valve 55a, b first check valve 56a, b second swing relief valve 57a, b second check valve 58a, b selector valve 65 controller 66 solenoid valve driver unit 67 diode unit 68 relay 69 battery 71 Pilot pipeline (pipeline)
77a, b Pressure sensor (first pressure sensor)

Claims (5)

In a hydraulic drive device for a construction machine, comprising a revolving unit, a working machine, and a revolving operation lever for operating the revolving unit,
A hydraulic pump, and a swing hydraulic motor that drives or brakes the swing body with pressure oil discharged from the hydraulic pump;
A turning direction control valve for controlling a flow of pressure oil supplied from the hydraulic pump to the turning hydraulic motor;
A first swing that is provided in one and the other oil passages connecting the swing direction control valve and the swing hydraulic motor, respectively, and restricts the driving pressure or the braking pressure of the swing hydraulic motor to be equal to or lower than a first set pressure. A relief valve,
A first switch that is provided in each of the oil passages and is switchable so that a driving pressure or a braking pressure of the swing hydraulic motor is equal to or lower than a second set pressure lower than the first set pressure by pilot pressure oil supplied to the operation unit. 2 swivel relief valves;
A switching valve that is provided in an oil passage on the upstream side of the second swing relief valve and communicates / blocks the swing hydraulic motor and the second swing relief valve by pilot pressure oil supplied to the operation section;
An electromagnetic valve that generates pilot pressure oil to be supplied to the operation portion of the switching valve and the operation portion of the second swing relief valve;
A hydraulic drive device for a construction machine, comprising: a control unit that outputs an operation signal for driving the electromagnetic valve. The hydraulic drive device for a construction machine according to claim 1,
A conduit for supplying a pilot primary pressure from a pilot pressure source to the solenoid valve;
An electromagnetic switching valve for switching communication / blocking of the pipe line;
Said control unit includes a solenoid valve driver which generates a controller for executing control operations, the control signal for driving the electric solenoid valve by a command signal from the controller,
A construction machine comprising: an electromagnetic switching valve drive circuit that drives the electromagnetic switching valve to bring the conduit into communication only when the command signal is output from the controller to the electromagnetic valve driver. Hydraulic drive device. The hydraulic drive device for a construction machine according to claim 2,
A first pressure sensor for detecting a pilot pressure when operating the turning operation lever;
A second pressure sensor for detecting a driving pressure or a braking pressure of the swing hydraulic motor,
The controller takes in the pilot pressure during operation of the turning operation lever from the first pressure sensor and the driving pressure or braking pressure of the turning hydraulic motor from the second pressure sensor, and according to these pressure signals A hydraulic drive device for a construction machine, wherein the command signal is output. The hydraulic drive device for a construction machine according to claim 2 or 3,
The controller outputs the control signal when the driving torque or braking torque of the swing hydraulic motor is reduced. The hydraulic drive device for a construction machine. The hydraulic drive device for a construction machine according to any one of claims 2 to 4,
The electromagnetic switching valve drive circuit includes a diode unit and a relay.

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