JP2012251329A - Revolving type work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a revolution type work machine having increased revolving energy regenerating efficiency by exerting regenerating action not only during revolving deceleration but also during power run, and also having improved operability by preventing a pressure fluctuation.SOLUTION: Communication valves 26, 27 are provided between both-motor-side ducts 14, 15 for communicating a motor-outlet-side duct with a tank T during revolving operation, and a revolving electric motor 30 and a battery 31 are provided which are driven by a revolving hydraulic motor 11. Thus, the communication valve opposite to the operation side is normally opened during revolving operation to reduce back pressure, and regenerating electric power equivalent to a reduction of the back pressure is generated by the revolving electric motor 30 and stored in the battery 31.

Description

  The present invention relates to a swivel work machine such as an excavator.

  The background art will be described using an excavator as an example.

  As shown in FIG. 5, the excavator is mounted on a crawler-type lower traveling body 1 so that an upper swing body 2 can swing around an axis X perpendicular to the ground, and an excavation attachment 3 is attached to the upper swing body 2. Configured.

  The excavation attachment 3 includes an up and down boom 4, an arm 5 attached to the tip of the boom 4, a bucket 6 attached to the tip of the arm 5, and a boom, an arm, and a bucket cylinder for operating them ( (Hydraulic cylinder) 7,8,9.

  In this excavator, a swing drive system described in Patent Document 1 is known as a swing drive system that swings the upper swing body 2.

  In this known technique, an electric motor is connected to a turning hydraulic motor as a drive source, and a short-circuit switching valve capable of short-circuiting the motor both-side pipes is provided between the motor both-side pipes and the control valve. In addition, the motor discharge oil is returned to the motor inlet side by the short-circuit switching valve, and the electric motor performs a generator action to generate regenerative power, and the generated regenerative power is stored in the capacitor.

  According to this configuration, the back pressure acting on the motor outlet side when the vehicle is decelerated by the short-circuit switching valve is reduced to reduce the accompanying load of the hydraulic motor, thereby increasing the recovery (regeneration) efficiency of inertial kinetic energy. .

  When this configuration is adopted, the hydraulic brake device including a pair of relief valves provided between the motor both-side pipelines does not work at the time of turning deceleration and performs only the stop holding function immediately after the turning stop.

JP 2010-65510 A

  However, according to the known technology, as described above, it helps to improve the regeneration efficiency during turning deceleration, but the regenerative action is not performed during turning power running, that is, during acceleration including start-up and steady operation. It was still insufficient in efficiency.

  In addition, the short-circuit switching valve is in the open position during turning power operation, and is switched to the short-circuit position during regeneration (during deceleration) .Therefore, a large pressure fluctuation occurs at the moment of switching, and the operability deteriorates at this point. there were.

  Therefore, the present invention can improve the regenerative efficiency of the turning energy not only at the time of turning deceleration but also at the time of power running and improve the operability by eliminating the large pressure fluctuation as in the known art. Provided is a swivel type working machine.

  As means for solving the above-mentioned problems, in the present invention, a lower traveling body, an upper swing body that is pivotably mounted on the lower traveling body, and a turning hydraulic motor as a swing drive source of the upper swing body A swing motor that is rotationally driven by the hydraulic motor, a capacitor, a hydraulic pump as a pressure oil supply source of the hydraulic motor, a swing operation means that commands acceleration, steady operation, deceleration, and stop of the swing, In a swing type work machine having a control valve for controlling supply and discharge of pressure oil to and from the hydraulic motor based on the operation of the swing operation means, a swing operation detection means for detecting the operation of the swing operation means, and a motor outlet side A communication valve that operates between a communication position for communicating the pipe line with the tank and a communication cutoff position for blocking the communication, and the swing electric motor based on a signal from the swing operation detecting means. Control means for controlling the regenerative action and the operation of the communication valve, and the control means sets the communication valve at the communication position during the turning operation of the upper-part turning body, and the back pressure generated by the communication valve. The regenerative control is performed so that the regenerative amount corresponding to the reduced amount is commanded to the swing electric motor.

  In this way, the back pressure is reduced by returning the motor discharge oil to the tank by the communication valve regardless of whether it is powering or decelerating, and the regenerative power corresponding to this back pressure reduction is reduced. Since it is the structure to generate | occur | produce, regeneration efficiency can be improved without raising the pump power at the time of turning power running, and the total energy-saving effect can be heightened.

  Further, since the communication valve is kept open throughout the turning operation, there is no pressure fluctuation due to switching of the switching valve as in the technique of Patent Document 1, and good operability can be ensured.

  In this case, a turning speed detecting means for detecting the turning speed and a pressure detecting means for detecting the outlet side pressure of the hydraulic motor are provided, and the control means is a meter of the control valve determined by an operation amount of the turning operation means. Calculate the motor outlet side pressure when there is no communication valve from the out opening area and the motor flow rate determined by the turning speed, and reduce the back pressure by subtracting the detected value of the motor outlet side pressure from this calculated value. It is desirable that the minutes be obtained (claim 2).

  According to this configuration, it is possible to accurately determine the amount of back pressure reduction and perform appropriate regenerative control without excessive or insufficient regenerative power.

  By the way, in a turning type work machine, the structure which drives several hydraulic actuators including the hydraulic motor for turning normally with one hydraulic pump is taken.

  In this configuration, when turning alone, the pump pressure during turning power is not so high and the back pressure is low. On the other hand, if the regenerative operation is performed in this state, the pump pressure rises. The total energy saving effect may be reduced.

  On the other hand, during combined operation, the pump pressure increases due to the operating pressure of the other hydraulic actuators, and the merit of reducing the back pressure and the effect of improving the regeneration efficiency are increased, so the total energy saving effect is increased.

  Therefore, when a configuration is adopted in which the hydraulic pump is shared by a plurality of hydraulic actuators including a turning hydraulic motor, the control means performs the regenerative control at the time of the turning single operation in which only the turning hydraulic motor operates. It is desirable that the regenerative control be performed only during the combined operation in which the turning hydraulic motor and the other hydraulic actuator are simultaneously operated.

  As described above, the regenerative control is not performed at the time of the single turning operation, but is performed only at the time of the combined operation, so that the energy saving effect can be maximized.

  According to the present invention, the regenerative action can be applied not only during turning deceleration but also during power running to improve the revolving efficiency of turning energy, and the operability can be improved without the large pressure fluctuation as in the known art. it can.

It is a system configuration figure showing an embodiment of the present invention. It is a flowchart for demonstrating the effect | action of embodiment. It is a figure which shows the relationship between the amount of turning operations and the meter-out opening area of a control valve in the conventional turning drive system which does not provide a communicating valve. It is a flowchart which shows 2nd Embodiment of this invention. 1 is a schematic side view of an excavator to which the present invention is applied.

  First and second embodiments of the present invention will be described with reference to FIGS. The embodiment is applied to an excavator.

  FIG. 1 shows the overall configuration of a turning drive system according to both embodiments.

  In FIG. 1, 10 is a hydraulic pump as a hydraulic source driven by an engine (not shown), and 11 is a turning hydraulic motor that is rotated by pressure oil from the hydraulic pump 10 to drive the upper swing body 2 of FIG. Thus, a control valve which is a hydraulic pilot type switching valve operated between the hydraulic pump 10 and the tank T and the hydraulic motor 11 by a remote control valve 12 (12a is an operation lever) as a turning operation means. 13 is provided.

  The remote control valve 12 is operated between the neutral position and the left and right turning positions. The pilot pressure from the remote control valve 12 causes the control valve 13 to move between the neutral position A and the left and right turning positions B and C shown in the figure. The operation is switched to control the supply and discharge of pressure oil to and from the hydraulic motor 11, that is, acceleration including turning start, steady operation at a constant speed, deceleration and stop, and the rotation direction and rotation speed.

  On the other hand, there is a pair of reliefs between the motor both-side pipes connecting the control valve 13 and the hydraulic motor 11 (hereinafter, the left side in the drawing may be referred to as the left turning pipe and the right side as the right turning pipe). A hydraulic brake device 20 including valves 16 and 17 and check valves 18 and 19 is provided.

  A relief valve circuit 21 that connects the relief valves 16 and 17 and a check valve circuit 22 that connects the check valves 18 and 19 are connected by a passage 23, and the passage 23 is connected by a makeup line 24 for sucking up oil. Connected to the tank T. Reference numeral 25 denotes a back pressure valve provided in the makeup line 24.

  The configuration up to this point is the same as that of a conventional hydraulic excavator turning drive system, and the operation of the above configuration alone is as follows.

  When the remote control valve 12 is not operated (when the lever 12a is neutral), the control valve 13 is set to the neutral position shown in the figure, and when the remote control valve is operated, the control valve 13 is positioned from the neutral position A to the left side of the figure (left turn position). Operates at a stroke corresponding to the operation amount of the remote control valve at the right or right position (right turn position) c.

  At the neutral position (a) of the control valve 13, since both the swirl lines 14 and 15 are blocked with respect to the pump 10, the hydraulic motor 11 does not rotate.

  From this state, when the remote control valve 12 is operated to the left or right turning side and the control valve 13 is switched to the left turning position B or the right turning position C, the pump 10 supplies the left turning line 14 or the right turning pipe. Pressure oil is supplied to the passage 15.

  As a result, the hydraulic motor 11 rotates to the left or right to enter a steady operation state in which the turning power running, that is, acceleration or constant speed including start-up.

  In this case, the oil discharged from the hydraulic motor 11 returns to the tank T via the control valve 13.

  Further, for example, when the remote control valve 12 is decelerated (returning to neutral or returning to neutral) during a right turning power running, pressure is generated in the left turning pipeline 14 on the meter-out side, and this becomes a constant value. When it reaches, the hydraulic brake device 20 works to decelerate and stop the upper swing body 2.

  The same applies to deceleration / stop from a left turn.

  Also, during this deceleration, if the turning pipeline 14 or 15 tends to have a negative pressure, tank oil is sucked into the turning pipeline 14 or 15 along the route of the makeup line 24, the passage 23, and the check valve circuit 22 to prevent cavitation. Is done.

  In the embodiment, in addition to the above-described configuration, both the left and right communication valves 26 and 27 are provided between the swivel conduits 14 and 15 and the tank T.

  The communication valves 26 and 27 are configured as electromagnetic switching valves that are switched between an open position a and a closed position b in response to a signal from a controller 28 serving as a control means, with an inlet side being a swirl line 14 and 15 and an outlet side being a passage. 29 are connected to the passages 23 of the hydraulic brake device 20 respectively.

  Here, since the passage 23 is connected to the tank T via the make-up line 24, when the communication valves 26 and 27 are set to the open position a, both the swirling pipelines 14 and 15 connect the control valve 13. It communicates directly with the tank T without any intervention.

  In addition, a swing electric motor 30 that is rotationally driven by the hydraulic motor 11 and a capacitor 31 are provided, and the regenerative power generated by the regenerative action of the swing motor 30 is stored in the capacitor 31.

  On the other hand, as the detecting means, pressure sensors 32 and 33 as turning operation detecting means for detecting the operation of the remote control valve 12 (whether the turning operation is neutral or left or right) through the pilot pressure from the remote control valve 12, and the turning electric motor 30 A speed sensor 34 as a turning speed detecting means for detecting the rotation speed (turning speed) of the motor, and a pressure sensor 35 as a pressure detecting means for detecting both side port pressures of the hydraulic motor 11 (motor outlet side pressure during the turning operation), 36, and signals (operation signal, speed signal, pressure signal) from these are input to the controller 28.

  The controller 28 determines whether the turning operation state or the stop state based on the signals from the sensors 32 to 36, and always during the turning operation during the turning operation, that is, during acceleration including startup, steady operation, and deceleration. Of the communication valves 26 and 27, the one on the opposite side to the operated side (the left communication valve 26 when turning right, the right communication valve 27. hereinafter referred to as the opposite communication valve when turning left) is switched to the open position a.

  Therefore, during the turning operation, the oil discharged from the hydraulic motor 11 is directly returned to the tank T through a route passing through the opposite communication valves 26 or 27 without passing through the control valve 13.

  For example, when turning right, the tank returns to the tank T through the route of the hydraulic motor 11, the left turning pipeline 14, the left communication valve 26, the passage 29, the passage 23, and the makeup line 24. For this reason, the return oil is not subjected to the squeezing action in the control 13.

  As a result, the back pressure acting on the meter-out side during the turning operation can be reduced, the pressure on the meter-in side can be reduced, and the pump pressure can be lowered, so that the power loss of the hydraulic pump 10 can be suppressed.

  During the turning operation, the turning electric motor 30 is driven by the hydraulic motor 11 and rotates in a so-called manner, and during this time, a generator (regeneration) action is performed based on a regeneration command from the controller 28.

  Due to this regenerative action, the battery 31 is always charged during the turning operation, and at the time of deceleration, the hydraulic motor 11 is braked by the regenerative brake, and the upper turning body is decelerated / stopped.

  Then, after the turning is stopped, the communication valves 26 and 27 are switched to the closed position b by a command from the controller 28.

  In this turning stop state, the upper turning body 2 of FIG. 5 is stopped and held by the braking action of the hydraulic brake device 20.

  In FIG. 1, reference numeral 37 denotes a main relief valve.

  The operation of the controller 28 in the first embodiment will be described with reference to the flowchart of FIG.

  After the start of control, it is determined in step S1 whether there is a turning operation signal (whether turning operation has been performed). If YES, it is determined in step S2 whether there is a turning speed signal (whether turning operation is being performed). .

  If NO in step S1 (no turning operation), it is determined in step S3 whether or not there is a turning speed signal. If YES in this case, the turning remote control valve 12 is operated to return to neutral for turning deceleration. However, it is assumed that the upper-part turning body 2 is still turning due to inertia, and the process proceeds to step S2.

  In step S2, it is determined whether or not there is a turning speed signal. If YES, the opposite communication valve 26 or 27 is opened in step S4.

  In subsequent steps S5 to S7, the motor outlet side pressure ΔP when the communication valves 26 and 27 are not provided (same as in the conventional circuit) is calculated from the swing operation amount and the swing speed, and the calculated value ΔP of the outlet side pressure is calculated. From this, the detected value P1 of the motor outlet side pressure is subtracted to obtain a reduction amount of the back pressure, and a regenerative amount (regenerative torque) corresponding to this back pressure reduction amount is determined and commanded to the swing motor 30.

  More specifically, the controller 28 stores in advance an opening characteristic representing the relationship between the turning operation amount and the meter-out opening area of the control valve 13 shown in FIG. 3, and a meter is calculated from the opening characteristic and the detected turning operation amount. The out opening area A is calculated.

  Further, the flow rate (swing flow rate) Q flowing to the hydraulic motor 11 is calculated from the detected turning speed, and the outlet side pressure ΔP is calculated by the following equation using the turning flow rate Q and the calculated meter-out opening area A. Is calculated (step S5).

Q = Cd · A√ (2ΔPb / ρ)
Cd: Flow coefficient
ρ: fluid density And from the calculated value ΔP of the outlet side pressure and the detected value P1,
ΔP-P1
Thus, a reduction amount of the back pressure by the communication valves 26 and 27 is obtained, a regeneration amount corresponding to the back pressure reduction amount is determined (step S6), and the regeneration amount is commanded to the swing motor 30 in step S7, and step S1 is performed. Return to.

  If NO in step S3 (turning operation is not performed and the turning speed is not output), it is determined that the turning is stopped, and the communication valves 26 and 27 are closed in step S8, and then NO (turning operation is performed in step S2). When the turning speed is not output), it is determined that the actual turning operation is not performed by the pressing work or the like, and the process directly proceeds to step S9, and the regeneration command to the turning motor 30 is not provided, and the process proceeds to step S1. Return.

  As described above, the back pressure is reduced by returning the motor discharge oil to the tank T by the communication valves 26 and 27 during the turning operation regardless of the power running or the deceleration, and the back electric motor 30 reduces the back pressure. Since it is the structure which generate | occur | produces the regenerative electric power equivalent to a reduction | decrease part, regenerative efficiency can be improved without raising the pump power at the time of turning power running, and the total energy saving effect can be heightened.

  Further, since the opposite side communication valve 26 or 27 is kept open throughout the turning operation, there is no pressure fluctuation due to switching of the switching valve as in the known technique described in Patent Document 1, and good operability is ensured. can do.

  Further, from the meter-out opening area A of the control valve 13 determined by the swing operation amount and the motor flow rate Q determined by the swing speed, the motor outlet side pressure ΔP when the communication valves 26 and 27 are not provided is calculated. By subtracting the detected value P1 of the motor outlet side pressure from the calculated value ΔP to obtain a reduction amount of the back pressure, the back pressure reduction amount can be accurately calculated, and appropriate regenerative control without excess or deficiency of regenerative power can be performed.

  Next, a second embodiment will be described with reference to FIG.

  In general, the excavator is configured to drive a plurality of hydraulic actuators including the turning hydraulic motor 11 with a single hydraulic pump.

  In this configuration, at the time of the single turning operation, the pump pressure during the turning power running is not so high and the back pressure is low, but if the regenerative action is performed on the turning electric motor 30 in this state, the pump pressure increases. There is a possibility that the total energy saving effect through the turning motion will decrease.

  On the other hand, during the combined operation, the pump pressure is increased by the operating pressure of the hydraulic actuator other than the turning hydraulic motor 11, and the merit of reducing the back pressure and the effect of improving the regeneration efficiency are increased, so that the total energy saving effect is increased.

  Therefore, in the second embodiment, when the hydraulic pump 10 is configured to be shared by a plurality of hydraulic actuators including the turning hydraulic motor 11, the above-described regenerative operation is performed at the time of the turning single operation in which only the turning hydraulic motor 11 is operated. The regenerative control is performed only during the combined operation in which the turning hydraulic motor 11 and the other hydraulic actuators operate simultaneously without performing the control.

  More specifically, steps S11 to S13 in FIG. 4 are the same as steps S1 to S3 in FIG. 2 (first embodiment).

  In step S14, it is determined whether or not there is another actuator operation (combined operation). If YES, in steps S15 to S18, the communication valve is opened as in steps S4 to S7 in FIG. Each process of calculation, the regeneration amount determination of the turning electric motor 30, and the regeneration instruction | command to the turning electric motor 30 is performed.

  If NO in step S13 (no turning operation or turning speed), it is assumed that the turning is stopped, and the communication valves 26 and 27 are closed in step S19, and if NO in step S12 and step S14, respectively. It moves to step S20 and returns to step S11 as there is no regeneration command to the turning electric motor 30.

  Thus, the energy saving effect can be maximized by performing the regenerative control only during the combined operation, not during the turning single operation.

Other embodiments
(1) In the embodiment described above, the outlet side of the communication valves 26 and 27 is connected to the passage 23 of the hydraulic brake device 20 via the passage 29, that is, the makeup line 24 is connected to the outlet side of the communication valves 26 and 27. However, a configuration in which the outlet sides of the communication valves 26 and 27 are connected to the tank T by a dedicated tank connection line may be employed.

  (2) In the above embodiment, the communication valves 26 and 27 are provided for each of the motor both-side pipe lines 14 and 15, but one communication valve shared by the both-side pipe lines 14 and 15 is provided, and this communication valve is closed. A configuration may be adopted in which switching control is performed between the left and right open positions (neutral position).

  (3) The present invention is not limited to the excavator, and can be similarly applied to other swivel work machines such as a dismantling machine and a crusher configured with the excavator as a base.

DESCRIPTION OF SYMBOLS 1 Lower traveling body 2 Upper revolving body 11 Turning hydraulic motor 12 Swing remote control valve as turning operation means 13 Control valve 14, 15 Motor both-side pipe lines 26, 27 Communication valve 28 Controller as control means 30 Turning electric motor 31 Capacitor 32, 33 Pressure sensor as turning operation detection means 34 Turning speed sensor 35 as turning speed detection means 35, 36 Pressure sensor for detecting motor outlet side pressure

Claims (3)

  A lower traveling body, an upper swinging body that is rotatably mounted on the lower traveling body, a swing hydraulic motor as a swing drive source of the upper swing body, and a swing motor that is rotationally driven by the hydraulic motor; A capacitor, a hydraulic pump as a pressure oil supply source of the hydraulic motor, a turning operation means for commanding acceleration, steady operation, deceleration, and stop of turning, and a pressure applied to the hydraulic motor based on the operation of the turning operation means In a swivel work machine having a control valve for controlling oil supply and discharge, a swivel operation detecting means for detecting the operation of the swivel operation means, a communication position for communicating the motor outlet side pipe line with the tank, and this communication. A control valve that operates between the communication cutoff position to be shut off, and a control unit that controls the regenerative action of the swing motor and the operation of the communication valve based on a signal from the swing operation detecting means. The control means sets the communication valve at the communication position during the swing operation of the upper swing body and commands the swing motor to generate a regenerative amount corresponding to a reduction in back pressure by the communication valve. A swivel working machine configured to perform regenerative control.   A turning speed detecting means for detecting a turning speed and a pressure detecting means for detecting an outlet side pressure of the hydraulic motor are provided, and the control means has a meter-out opening area of the control valve determined by an operation amount of the turning operation means. And the motor flow rate determined by the turning speed, the motor outlet side pressure when there is no communication valve is calculated, and the detected value of the motor outlet side pressure is subtracted from this calculated value to obtain the reduced back pressure. The revolving work machine according to claim 1, which is configured as described above.   The hydraulic pump is shared by a plurality of hydraulic actuators including a turning hydraulic motor, and the control means does not perform the regenerative control during the turning single operation in which only the turning hydraulic motor operates, and does not perform the regenerative control. The revolving control machine according to claim 1 or 2, wherein the regenerative control is performed only during a combined operation in which a hydraulic motor and another hydraulic actuator operate simultaneously.

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