JP6473631B2 - Hydraulic control equipment for construction machinery - Google Patents

Description

  The present invention relates to a hydraulic control device provided in a construction machine such as a hydraulic excavator.

  For example, a hydraulic excavator described in Patent Document 1 is attached to a boom that is rotatably attached to the upper swing body in the up and down directions, a boom cylinder that drives the boom, and a boom that is rotatably attached to the boom. And an arm cylinder for driving the arm, and a variable displacement hydraulic pump for supplying hydraulic oil to the arm cylinder.

  In this hydraulic excavator, hydraulic fluid is returned from the boom cylinder to the discharge passage of the hydraulic pump in order to utilize the potential energy of the boom during the two-type combined operation in which the boom lowering operation and the arm operation are performed simultaneously. The hydraulic pump flow is reduced by the oil flow.

  Specifically, the hydraulic excavator includes an actuator regenerative circuit (regenerative flow path and second flow rate adjusting unit) provided between the head side chamber of the boom cylinder and the discharge passage of the hydraulic pump, and return oil through the actuator regenerative circuit. And a controller for controlling the flow rate and the capacity of the hydraulic pump.

  Further, in the hydraulic excavator described in Patent Document 1, when there is surplus hydraulic oil that cannot be returned to the discharge passage of the hydraulic pump among hydraulic oil derived from the boom cylinder during the boom lowering operation, the hydraulic oil has Energy is stored by the accumulator.

  Specifically, the hydraulic excavator described in Patent Document 1 includes an accumulator and an accumulator regenerative circuit (a pressure accumulation channel, a first flow rate adjustment unit) provided between the head side chamber of the boom cylinder and the accumulator. . The controller controls the flow rate of the return oil accumulated in the accumulator through the accumulator regeneration circuit.

  According to the hydraulic excavator described in Patent Literature 1, it is possible to efficiently use the potential energy of the boom at the time of the two-type combined operation of the boom lowering operation and the arm operation.

  In addition, in construction machines that include a lower body, an upper swing body that is turnable on the lower body, and a swing motor that drives the upper swing body to swing, use the inertia energy of the upper swing body during swing braking In order to do this, there is also known one that regenerates return oil from the turning motor.

  Specifically, this construction machine includes a regenerative motor connected to a drive shaft of an engine that drives a hydraulic pump, and a motor regeneration circuit provided between the swing motor and the regenerative motor.

  According to the construction machine, the hydraulic oil is supplied to the regenerative motor through the motor regenerative circuit at the time of turning braking, so that the engine can be assisted by the inertia energy of the upper turning body at the time of turning braking.

JP 2008-89024 A

  Here, at the time of the three-type combined operation in which the boom lowering operation, the arm operation, and the turning deceleration operation are performed simultaneously, the discharge flow rate of the hydraulic pump is reduced by using the potential energy of the boom (the power of the engine is reduced). It is possible to add the structure which assists an engine with the inertial energy of an upper turning body with respect to the hydraulic shovel described in 1 above.

  However, there is a problem that sufficient regeneration efficiency cannot be obtained by simply combining these configurations.

  Specifically, since the power required for the hydraulic pump is small in the state where the discharge flow rate of the hydraulic pump is reduced using the potential energy of the boom, the power of the hydraulic pump (engine power) out of the inertia energy of the upper swing body. The portion that can be used as power is limited.

  An object of the present invention is to provide a construction machine capable of obtaining sufficient regenerative efficiency by effectively utilizing the positional energy of the boom and the inertial energy of the upper-part turning body during the three-type combined operation.

In order to solve the above-described problems, the present invention is provided with a lower body, an upper swing body provided on the lower body so as to be rotatable, and attached to the upper swing body so as to be rotatable in an upward direction and a downward direction. A hydraulic control device for a construction machine having a boom, for driving a swing motor that drives the upper swing body to swing, a boom cylinder that drives the boom, and a driven body provided in the construction machine Between the hydraulic actuator, a variable displacement hydraulic pump that supplies hydraulic oil to the hydraulic actuator, an engine that drives the hydraulic pump, a head side chamber of the boom cylinder, and a discharge passage of the hydraulic pump An actuator regenerative circuit, an accumulator, and a boom cylinder head that are provided and are capable of adjusting a flow rate of hydraulic oil from the head side chamber to the discharge passage. An accumulator regenerative circuit provided between a head side chamber and the accumulator, and capable of adjusting a flow rate of hydraulic oil from the head side chamber to the accumulator, a regenerative motor connected to a drive shaft of the engine, and the regenerative motor A motor regeneration circuit that is provided between the swing motor and is switchable between a permissible state that allows supply of hydraulic oil from the swing motor to the regenerative motor and a prohibited state that is prohibited; and a controller. The controller controls the actuator regenerative circuit based on a regenerative flow rate that can be supplied from the head side chamber to the discharge passage during a two-type combined operation of the boom lowering operation and the operation of the driven body, Controlling the accumulator regeneration circuit based on a pressure accumulation flow rate that can be supplied from a side chamber to the accumulator; While the flow rate obtained by subtracting the regenerative flow from the discharge flow rate of the pressure pump to reduce the capacity of the hydraulic pump so as to obtain, Oite during turning deceleration of the upper rotating body, switching control of the motor regenerative circuit to the allowing state and, before Symbol three composite during operation boom lowering operation and the and the operation of the driven member and the pivot deceleration of the upper rotating body are simultaneously performed, and switching control of the motor regenerative circuit to the allowing state, this Provided is a hydraulic control device for a construction machine that specifies the regenerative flow rate and the accumulated pressure flow rate in a state, and further controls the actuator regeneration circuit and the accumulator regenerative circuit based on the identified regenerative flow rate and the accumulated pressure flow rate.

  According to the present invention, since the regeneration using the return oil from the swing motor is performed with priority over the regeneration using the return oil from the boom cylinder, the discharge flow rate of the hydraulic pump is reduced according to the regeneration flow rate. Thus, the assist power can be increased as compared with the case where the power regenerated by the return oil from the turning motor (hereinafter referred to as assist power) is set. Therefore, the inertial energy of the upper swing body can be used effectively.

  Here, when the assist power is increased, the discharge flow rate of the hydraulic pump is maintained higher than that in the case of the two-type combined operation. For this reason, power required for the hydraulic pump (hereinafter referred to as required power) may be limited by the regenerative flow rate, but the hydraulic oil from the head side chamber is not limited to the discharge path of the hydraulic pump. It can also be supplied to an accumulator.

  Therefore, in the present invention, the regenerative flow rate and the accumulated pressure flow rate are specified in a state where the motor regenerative circuit is switched to the allowable state (a state where the assist power is regenerated). As a result, the hydraulic oil whose supply to the discharge passage side is limited among the return oil from the boom cylinder can be guided to the accumulator, and the potential energy of the boom can be effectively utilized.

  Therefore, according to the present invention, sufficient regeneration efficiency can be obtained by effectively utilizing the potential energy of the boom and the inertial energy of the upper-part turning body during the three-type combined operation.

  Here, if the assistable power that can be borne by using all the hydraulic oil derived from the swing motor exceeds the required power required for the hydraulic pump, if the required power is maintained, the engine accompanying an increase in the engine speed May occur.

  Therefore, in the hydraulic control device for the construction machine, the controller requires the hydraulic pump to be capable of assisting using all the hydraulic oil derived from the swing motor during the three-type combined operation. It is preferable to increase the capacity of the hydraulic pump so that the required power exceeds the assistable power when the required power exceeds the required power.

  According to this aspect, by increasing the capacity of the hydraulic pump, that is, the power of the engine, it is possible to prevent the engine from being blown up when all assistable power is used.

  On the other hand, as the capacity of the hydraulic pump increases, the regenerative flow rate is further limited. As described above, of the return oil from the boom cylinder, the hydraulic oil whose supply to the discharge passage is restricted can be guided to the accumulator.

  Further, in order to prevent the engine from blowing up, in the hydraulic control device for the construction machine, the regenerative motor is a variable capacity motor, and the controller is configured to operate from the swing motor during the three-type combined operation. When the assistable power that can be borne by using all the derived hydraulic fluid exceeds the required power required for the hydraulic pump, the regenerative power is reduced so that the power regenerated by the regenerative motor is less than the required power. The motor can also be controlled.

  According to this aspect, when the assistable power exceeds the required power, it is possible to prevent the engine from blowing up by adjusting the assist power to be equal to or lower than the required power.

  Moreover, according to the said aspect, compared with the case where the large capacity | capacitance regenerative motor which can absorb all the power which can be assisted is employ | adopted, the capacity | capacitance reduction of a regenerative motor, ie, size reduction, can also be achieved.

  Here, when the required power is increased to the power exceeding the assistable power, the hydraulic pump driven by the power exceeding the original required power discharges the surplus hydraulic oil, and the energy of the surplus hydraulic oil is a relief valve, etc. Discarded as heat.

  Therefore, in the hydraulic control apparatus for the construction machine, the controller is configured so that, when the assistable power exceeds the required power during the three-type combined operation, the required power is substantially equal to the assistable power. It is preferable to increase the capacity of the hydraulic pump.

  According to this aspect, the energy discarded as heat by the relief valve or the like can be minimized while preventing the engine from blowing up when all assistable power is used as described above.

  Here, when the assist power is smaller than the required power, a part of the power of the hydraulic pump (engine power) can be reduced by the amount of power borne by the regenerative flow rate.

  Specifically, in the hydraulic control device for the construction machine, the controller is configured to determine the power from the discharge flow rate of the hydraulic pump when the power regenerated by the regenerative motor is smaller than the required power during the three-type combined operation. It is preferable to reduce the capacity of the hydraulic pump so that a flow rate obtained by reducing the regenerative flow rate can be obtained.

  According to this aspect, the power of the engine can be reduced by reducing the capacity of the hydraulic pump.

  According to the present invention, sufficient regeneration efficiency can be obtained by effectively utilizing the potential energy of the boom and the inertial energy of the upper-part turning body during the three-type combined operation.

1 is a side view showing an overall configuration of a hydraulic excavator according to a first embodiment of the present invention. It is a circuit diagram which shows the hydraulic system of the hydraulic shovel of FIG. It is a block diagram which shows the electric system of the hydraulic shovel of FIG. It is a flowchart which shows the process performed by the controller of FIG. It is a table | surface which shows Example 1 of the distribution state of motive power. It is a table | surface which shows the distribution state by Example 2 and 2nd Embodiment of the distribution state of motive power.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The following embodiments are examples embodying the present invention, and are not of a nature that limits the technical scope of the present invention.

<First Embodiment>
Referring to FIG. 1, a hydraulic excavator 1 as an example of a construction machine according to a first embodiment of the present invention is capable of turning on a lower traveling body (lower body) 2 having a crawler 2 a and a lower traveling body 2. The upper revolving body 3 provided and the attachment 4 attached to the upper revolving body 3 are provided.

  The attachment 4 includes a boom 6 that is rotatably attached to the upper swing body 3 in the upward and downward directions, and an arm (covered) that is rotatably attached to the tip of the boom 6 in the pushing and pulling directions. Drive body) 7 and a bucket 8 that is rotatably attached to the tip of the arm 7.

  The attachment 4 includes a boom cylinder 9 that drives the boom 6, an arm cylinder (an example of a hydraulic actuator) 10 that drives the arm 7, and a bucket cylinder 11 that drives the bucket 8.

  The boom 6 operates in the up direction when the rod of the boom cylinder 9 extends, and operates in the down direction when the rod of the boom cylinder 9 contracts. The arm 7 operates in the pulling direction when the rod of the arm cylinder 10 extends, and operates in the pushing direction when the rod of the arm cylinder 10 contracts.

  The upper swing body 3 includes a swing motor 3a that drives the upper swing body 3 to rotate relative to the lower traveling body 2, a hydraulic system 12 shown in FIG. 2, and a controller 13 shown in FIG.

  Referring to FIG. 2, the hydraulic system 12 includes a variable displacement first hydraulic pump 14 that supplies hydraulic oil to the boom cylinder 9, and a variable displacement first hydraulic pump 14 that supplies hydraulic oil to the arm cylinder 10 and the swing motor 3a. 2 hydraulic pump (an example of a hydraulic pump) 15, an engine 16 for driving both hydraulic pumps 14, 15, a regenerative motor 17 connected to the output shaft of the engine 16, and a boom drive circuit 18 for driving the boom 6. An arm drive circuit 19 for driving the arm 7, a swing drive circuit 20 for driving the upper swing body 3 to swing, and an arm regeneration circuit for regenerating the return oil from the boom cylinder 9 to the arm cylinder 10. (Actuator regeneration circuit) 21, accumulator 42, and accumulator for accumulating accumulator 42 with return oil from boom cylinder 9 Raw circuit 22, and a motor regeneration circuit 23 for operating the regenerative motor 17 by the return oil from the swing motor 3a.

  The second hydraulic pump 15 has a pump adjuster 15b, and the capacity of the second hydraulic pump 15 is adjusted by receiving an instruction from the controller 13 described later. Further, the discharge pressure of the second hydraulic pump 15 is detected by a discharge pressure detection sensor 15a.

  The regenerative motor 17 has a motor adjuster 17 a, and the capacity of the regenerative motor 17 is adjusted when the motor adjuster 17 a receives a command from the controller 13. Further, the regenerative motor 17 is connected to both circuits 22 and 23 via a shuttle valve 17b so as to be connected to a high-pressure side circuit among an accumulator regenerative circuit 22 and a motor regenerative circuit 23 which will be described later. .

  The boom drive circuit 18 performs a control valve 24 provided between the first hydraulic pump 14 and the boom cylinder 9, a boom operating means 25 for operating the control valve 24, and an operation for lowering the boom 6. A boom lowering operation detection sensor 26 capable of detecting the breakage and a head pressure detection sensor 27 capable of detecting the pressure in the head side chamber of the boom cylinder 9 are provided.

  The control valve 24 has a neutral position for stopping the boom 6, a boom lowering position (right side position in the figure) for driving the boom 6 in the downward direction, and a boom raising position for driving the boom 6 in the upward direction. It is possible to switch between (the left position in the figure). The control valve 24 is biased to the neutral position in a state where the boom operation means 25 is not operated.

  The boom operation means 25 has a remote control valve and an operation lever. By operating the operation lever, hydraulic oil (pilot pressure) from a pilot pump (not shown) can be supplied to both pilot ports of the control valve 24. is there.

  The boom lowering operation detection sensor 26 can detect the operation amount of the boom lowering by the boom operating means 25 as a pilot pressure. The hydraulic system 12 is also provided with a boom raising operation detection sensor, which is omitted for simplification of the drawing.

  The arm drive circuit 19 is operated by a control valve 28 provided between the second hydraulic pump 15 and the arm cylinder 10, arm operating means 29 for operating the control valve 28, and operation of the arm 7 in the pushing direction. An arm push operation detection sensor 30 capable of detecting the breakage and a rod pressure detection sensor 31 capable of detecting the pressure in the rod side chamber of the arm cylinder 10 are provided.

  The control valve 28 has a neutral position for stopping the arm 7, an arm pushing position for driving the arm 7 in the pushing direction (right side position in the figure), and an arm pulling position for driving the arm 7 in the drawing direction. It is possible to switch between (the left position in the figure). The control valve 28 is biased to the neutral position in a state where the arm operating means 29 is not operated.

  The arm operation means 29 has a remote control valve and an operation lever. By operating the operation lever, hydraulic oil (pilot pressure) can be supplied to both pilot ports of the control valve 28 from a pilot pump (not shown). .

  The arm push operation detection sensor 30 can detect the amount of arm push operation by the arm operation means 29 as a pilot pressure. The hydraulic system 12 is also provided with an arm pulling operation detection sensor, but is omitted for simplification of the drawing.

  The turning drive circuit 20 includes a control valve 32 provided between the second hydraulic pump 15 and the turning motor 3a, a turning operation means 33 for operating the control valve 32, and a right turning operation of the upper turning body 3. A right turn operation detection sensor 34 that can detect that the left turn operation has been performed, a left turn operation detection sensor 35 that can detect that the left turn operation of the upper swing body 3 has been performed, the control valve 32, and the turn motor 3a. Between the brake circuit 36, the right turning pressure detection sensor 37 that can detect the pressure in the right turning passage of the turning motor 3a, and the left turning that can detect the pressure in the left turning passage of the turning motor 3a. And a pressure detection sensor 38.

  The control valve 32 is a neutral position for stopping the upper swing body 3, a right swing position (upper position in the figure) for driving the upper swing body 3 to the right, and a left swing drive for the upper swing body 3. To the left turn position (lower position in the figure). The control valve 32 is biased to the neutral position in a state where the turning operation means 33 is not operated.

  The turning operation means 33 has a remote control valve and an operation lever. By operating the operation lever, pilot pump hydraulic oil (pilot pressure) (not shown) can be supplied to both pilot ports of the control valve 32.

  The right turning operation detection sensor 34 can detect a right turning operation by the turning operation means 33 as a pilot pressure, and the left turning operation detection sensor 35 can detect a left turning operation by the turning operation means 33 as a pilot pressure. is there.

  The brake circuit 36 applies back pressure to a high-pressure side passage (hereinafter referred to as a high-pressure side passage) of the right turning passage and the left turning passage of the turning motor 3a in a state where the control valve 32 is operated to the neutral position. Supply hydraulic fluid to the low pressure side passage (hereinafter referred to as the low pressure side passage).

  Specifically, the brake circuit 36 guides the hydraulic oil from the high pressure side passage to the low pressure side passage when the relief valve 36a is opened, and a pair of relief valves 36a that are opened when the high pressure side passage exceeds the relief pressure. And a boost check valve 36c for guiding hydraulic oil that cannot be guided to the low pressure side passage out of the hydraulic oil through the relief valve 36a to the tank.

  The arm regeneration circuit 21 is provided between the head side passage of the boom cylinder 9 and the rod side passage of the arm cylinder 10 (between the head side chamber of the boom cylinder 9 and the discharge passage of the second hydraulic pump 15). The flow rate of the hydraulic oil from the head side passage 9 to the rod side passage of the arm cylinder 10 can be adjusted.

  Specifically, the arm regeneration circuit 21 includes an arm regeneration passage 39 that connects the head side passage of the boom cylinder 9 and the rod side passage of the arm cylinder 10, and an arm regeneration valve 40 provided in the arm regeneration passage 39. ing. The arm regenerative valve 40 is an electromagnetic valve that is urged to the closed position in a state where a command is not output from the controller 13 to be described later, and that can adjust the flow rate of the hydraulic oil in the arm regenerative passage 39 by a command from the controller 13. .

  Reference numeral H1 denotes a holding valve for holding the boom 6 so that the boom 6 is not lowered while the control valve 24 is in the neutral position.

  The accumulator regeneration circuit 22 is provided between the head side passage of the boom cylinder 9 (the head side chamber of the boom cylinder 9) and the accumulator 42, and can adjust the flow rate of hydraulic oil from the head side passage of the boom cylinder 9 to the accumulator 42. It is.

  Specifically, the accumulator regenerative circuit 22 includes an accumulator passage 41 that connects the head side passage of the boom cylinder 9 and the accumulator 42, and an accumulator regenerative valve 43 that can adjust the flow rate of hydraulic oil from the head side passage to the accumulator 42 ( Hereinafter, the ACC regenerative valve 43), the pressure release valve 44 capable of adjusting the flow rate of the hydraulic oil discharged from the accumulator 42, and the flow rate of the hydraulic oil discharged from the head side passage to the tank can be adjusted. A meter-out valve 46 (hereinafter referred to as “M / O valve 46”) and a pressure accumulation sensor 47 capable of detecting the pressure of hydraulic oil accumulated in the accumulator 42 are provided.

  The ACC regenerative valve 43 is provided on the upstream side (boom cylinder 9 side) of the accumulator 42 in the accumulator passage 41. The ACC regenerative valve 43 is an electromagnetic valve that is urged to a closed position in a state in which a command is not output from the controller 13 to be described later, and that can adjust the flow rate of the hydraulic oil in the accumulator passage 41 by a command from the controller 13.

  The pressure relief valve 44 is provided on the downstream side (shuttle valve 17 b side) of the accumulator 42 in the accumulator passage 41. The pressure release valve 44 is an electromagnetic valve that is urged to a closed position in a state where a command is not output from the controller 13 to be described later, and that can adjust the flow rate of the hydraulic oil in the accumulator passage 41 by a command from the controller 13. By opening the pressure release valve 44 in a state where the ACC valve 43 is switched to the closed position, the regenerative motor 17 is operated by the hydraulic oil stored in the accumulator 42.

  The M / O valve 46 is provided in a meter-out passage 45 that connects the position of the accumulator passage 41 on the upstream side of the ACC regeneration valve 43 and the tank. The M / O valve 46 is an electromagnetic valve that is urged to the closed position in a state in which no command is output from the controller 13 described later, and can adjust the flow rate of the hydraulic oil in the meter-out passage 45 by a command from the controller 13. is there.

  Reference numeral H2 is a holding valve for holding the boom 6 so that the boom 6 is not lowered while the control valve 24 is in the neutral position. The holding valve is also provided between the control valve 24 and the head side chamber of the boom cylinder 9, but is omitted for simplification of the drawing.

  The motor regeneration circuit 23 is provided between the regeneration motor 17 and the swing motor 3a, and can be switched between a state in which hydraulic oil is supplied from the swing motor 3a to the regeneration motor 17 and a state in which it is stopped.

  Specifically, the motor regeneration circuit 23 includes a right communication passage 48 connected to a right turning port (right turning passage) of the turning motor 3a and a left turning port (left turning passage) of the turning motor 3a. A left communication passage 49 connected to the right communication passage 48, a right regenerative valve 50 provided in the right communication passage 48, and a left regenerative valve 51 provided in the left communication passage 49.

  The right regenerative valve 50 is an electromagnetic valve that is urged to the closed position in a state in which a command from the controller 13 to be described later is not output, and that can adjust the flow rate of the hydraulic oil in the right communication passage 48 by a command from the controller 13. is there.

  The left regenerative valve 51 is an electromagnetic valve that is urged to a closed position in a state where a command from the controller 13 to be described later is not output and can adjust the flow rate of the hydraulic oil in the left communication passage 49 by a command from the controller 13. is there.

  The two communication passages 48 and 49 converge to one passage at a position downstream of the regenerative valves 50 and 51, and the one passage is connected to the regenerative motor 17 via the shuttle valve 17b.

  The turning speed of the turning motor 3a is detected by the turning speed sensor 3b.

  Referring to FIG. 3, the controller 13 includes a boom lowering operation detection sensor 26, an arm pushing operation detection sensor 30, a right turn operation detection sensor 34, a left turn operation detection sensor 35, a head pressure detection sensor 27, and a rod pressure detection. Detection signals from the sensor 31, the right turning pressure detection sensor 37, the left turning pressure detection sensor 38, the pressure accumulation detection sensor 47, the discharge pressure detection sensor 15a, and the turning speed sensor 3b are input. The controller 13 also adjusts the arm regenerative valve 40, the ACC pressure accumulating valve 43, the M / O valve 46, the pressure relieving valve 44, the right regenerative valve 50, the left regenerative valve 51, the pump regulator 15b, and the motor based on the detection signal. An operation command is output to the device 17a.

  Specifically, the controller 13 executes the following control at the time of the two-type combined operation of the lowering operation of the boom 6 and the pushing operation of the arm 7.

<Control during 2 types of combined operation>
Referring to FIG. 2, the controller 13 controls the arm regeneration circuit 21 based on the regeneration flow rate that can be supplied from the head side chamber of the boom cylinder 9 to the rod side passage of the arm cylinder 10. In addition, the controller 13 controls the accumulator regeneration circuit 22 based on the accumulated pressure flow rate that can be supplied from the head side chamber of the boom cylinder 9 to the accumulator 42. Further, the controller 13 controls the capacity of the second hydraulic pump 15 so that a flow rate obtained by subtracting the regenerative flow rate from the discharge flow rate of the second hydraulic pump 15 is obtained. The discharge flow rate of the second hydraulic pump 15 is specified based on the operation amounts of the arm operation means 29 and the turning operation means 33.

  The regenerative flow rate and the accumulated flow rate are calculated by the following equation (1).

Q = A × C × √ΔP (1)
Here, Q is the flow rate, A is the opening area of the regenerative valve, and ΔP is the difference between the primary side pressure and the secondary side pressure of the regenerative valve.

  When obtaining the regenerative flow rate, first, the maximum regenerative flow rate due to the return oil from the boom cylinder 9 is calculated using Equation (1). Specifically, the maximum opening area of the arm regenerative valve 40 is substituted for A, and the rod side pressure (detected by the rod pressure detection sensor 31) of the arm cylinder 10 from the head side pressure (detected pressure by the head pressure detection sensor 27) of the boom cylinder 9 to ΔP. Substitute the value obtained by subtracting the detection pressure. Next, the regenerative flow rate that can be supplied to the arm cylinder 10 is calculated based on the maximum regenerative flow rate and the supply flow rate of hydraulic oil to the arm cylinder 10 that is determined by the operation amount of the arm operation means 29 (hereinafter referred to as the required flow rate). By calculating the regenerative flow rate, the opening area A of the arm regenerative valve 40 is calculated based on the equation (1).

  When obtaining the accumulated pressure flow rate, first, the maximum accumulated pressure flow rate of the hydraulic oil that can be supplied to the accumulator 42 is calculated using the equation (1). Specifically, the maximum opening area of the ACC regenerative valve 43 is substituted for A, and the value obtained by subtracting the pressure of the accumulator 42 (the pressure detected by the pressure accumulation sensor 47) from the head side pressure of the boom cylinder 9 is substituted for ΔP. Next, based on the remaining flow rate obtained by subtracting the regenerative flow rate from the maximum regenerative flow rate and the maximum accumulated pressure flow rate, the accumulated pressure flow rate that can be supplied to the accumulator 42 is calculated. By calculating the pressure accumulation flow rate, the opening area A of the ACC regenerative valve 43 is calculated based on the equation (1).

  Of the return oil from the boom cylinder 9, the hydraulic oil that cannot be supplied to both the arm cylinder 10 and the accumulator 42 is collected in the tank through the M / O valve 46. The opening area of the M / O valve 46 is calculated by the above (1) based on a value obtained by subtracting the regenerative flow and the accumulated flow from the maximum regenerative flow and the head side pressure of the boom cylinder 9.

  On the other hand, the controller 13 executes the following control when the upper swing body 3 is decelerated.

<Control during turning deceleration>
The controller 13 controls the motor regeneration circuit 23 so that hydraulic oil is supplied from the swing motor 3a to the regenerative motor 17 at the time of turning deceleration.

  Further, the controller 13 controls the regenerative motor 17 based on the required power required for the second hydraulic pump 15.

  The required power is obtained by the product of the discharge flow rate and the discharge pressure of the second hydraulic pump 15. The discharge pressure of the second hydraulic pump 15 is detected by a discharge pressure detection sensor 15a.

  Further, the controller 13 calculates assistable power that can be borne by using all the hydraulic oil derived from the turning motor 3a. The assistable power is calculated by the turning speed of the upper swing body 3 (detection speed by the turning speed sensor 3b), the capacity of the turning motor 3a, and the reduction ratio by a turning bearing (not shown).

  The controller 13 sets assist power equivalent to the required power when the assistable power is greater than or equal to the required power, and sets assist power equivalent to the assistable power when the assistable power is smaller than the required power. .

  Here, the power (assist power) of the regenerative motor 17 is determined by the product of the hydraulic oil pressure (the pressure on the high pressure side of the pressure detected by the swivel pressure detection sensors 37 and 38) and the capacity of the regenerative motor 17. Therefore, the controller 13 switches the regenerative valve on the high pressure side of the right regenerative valve 50 and the left regenerative valve 51 to fully open during turning deceleration, and controls the capacity of the regenerative motor 17 so that the assist power can be obtained.

  Furthermore, the controller 13 performs the following control during the three-type combined operation in which the lowering operation of the boom 6, the pushing operation of the arm 7, and the turning deceleration operation of the upper turning body 3 are simultaneously performed.

<Control during 3 types of combined operation>
The controller 13 includes a motor regeneration process for performing regeneration of the regenerative motor 17 by the return oil from the swing motor 3a, an actuator regeneration process for using the return oil of the boom cylinder 9 to drive the arm cylinder 10, and an accumulator by the return oil of the boom cylinder 9. The accumulator regeneration process for accumulating 42 is executed in this order. After the motor regeneration process, the actuator regeneration process and the accumulator regeneration process can be performed in parallel.

  In the motor regeneration process, the controller 13 identifies the assistable power and the required power in the same manner as the control during the turning braking operation described above in order to identify the assist power that is borne by the hydraulic oil from the motor regeneration circuit 23. .

  When the assistable power exceeds the required power, the controller 13 increases the capacity of the second hydraulic pump 15 (increases the required power) and assists the assistable power so that the required power becomes equal to or higher than the assistable power. Set to power.

  Thereby, even when the assistable power is larger than the required power, it is possible to prevent the engine 16 from blowing up when all the assistable power is used.

  On the other hand, when the assistable power is equal to or less than the required power, the controller 13 sets the assistable power as the assist power while maintaining the capacity of the second hydraulic pump 15 (while maintaining the required power).

  Then, the controller 13 fully opens the high pressure side regenerative valve of the right regenerative valve 50 and the left regenerative valve 51 and controls the capacity of the regenerative motor 17 so as to obtain assist power.

  In the actuator regeneration process that is executed after the motor regeneration process, the controller 13 identifies and identifies the regenerative flow rate based on the maximum regenerative flow rate and the required flow rate of the arm cylinder 10 as in the case of the above-described two-type combined operation. The arm regenerative valve 40 is controlled based on the regenerative flow rate.

  In the three-type combined operation, the motor regeneration process is executed in preference to the actuator regenerative process, so that the discharge flow rate of the second hydraulic pump 15 is maintained in a larger state than in the two-type combined operation. For this reason, among the required power of the second hydraulic pump 15, the power that is borne by the regenerative flow may be limited as compared to the time of the two-type combined operation. The power limited in this way is accumulated in the accumulator 42 in an accumulator regeneration process to be described later.

  In the actuator regeneration process, the controller 13 regenerates the discharge flow rate of the second hydraulic pump 15 from the discharge flow rate determined by the operation amounts of the arm operation means 29 and the turning operation means 33 when the assistable power is less than the required power. The capacity of the second hydraulic pump 15 is reduced so that the flow rate is reduced.

  In the accumulator regenerative process executed after the actuator regenerative process, the controller 13 is based on the remaining flow rate obtained by subtracting the regenerative flow rate from the maximum regenerative flow rate and the maximum accumulated pressure flow rate, similarly to the control during the two-type combined operation. To calculate the accumulated pressure flow.

  Similar to the control during the two-type combined operation described above, the hydraulic oil that cannot be supplied to both the arm cylinder 10 and the accumulator 42 among the return oil from the boom cylinder 9 is supplied to the tank through the M / O valve 46. Collected.

  Hereinafter, processing executed by the controller 13 will be described with reference to FIGS. 2 and 4.

  When the process is started, it is determined whether or not the boom 6 lowering operation and the arm 7 pushing operation are performed based on the detection values of the boom lowering operation detection sensor 26 and the arm push operation detection sensor 30 (step). S1).

If it is determined NO in step S1, it is determined whether or not the upper swing body 3 is being decelerated (step S2). Specifically, in step S 2, the state where the upper turning body 3 that has been detected is turning turning speed sensor 3b, when the turning operation by the turning operation detection sensor 35 is not detected It is determined that the vehicle is turning and decelerating.

  If NO is determined in step S2, step S1 is repeatedly executed. If YES is determined in step S2, the above-described regenerative control during turning deceleration is executed (step S3), and the process returns.

  If YES is determined in step S1, it is determined whether or not a regenerative condition set in advance as a condition for allowing the return oil from the boom cylinder 9 to be regenerated in the arm cylinder 10 is satisfied (step S4). ).

  If NO is determined in step S4, step S1 is repeatedly executed.

  On the other hand, if it determines with YES by step S4, it will be determined whether the upper turning body 3 is decelerating (step S5).

  When it is determined in step S5 that the upper-part turning body 3 is not decelerating, the regeneration control S6 during the above-described two-type combined operation is executed, and the process returns.

  On the other hand, when it is determined in step S5 that the upper-part turning body 3 is turning and decelerating, that is, the three-type combined operation is being performed, the regeneration control during the three-type combined operation in steps S7 to S9 is executed. Hereinafter, the contents of this control will be described with reference to FIGS.

  In FIG. 5, the regenerative power of the boom cylinder 9 is 100, the assistable power of the swing motor 3 a is 40, the accumulator 42 is capable of accumulating power, and the required power of the second hydraulic pump 15 is 70. It shows the distribution of power in some cases. FIG. 6 shows power distribution when the assistable power of the turning motor 3a is 100, unlike FIG. In addition, said numerical value is a standard for demonstrating motive power distribution, and does not show actual motive power.

  In the motor regeneration process in step S7, assist power is set.

  In Example 1 of FIG. 5, since the assistable power (40) is smaller than the required power (70), all of the assistable power (40) is set as the assist power as shown in [1].

  On the other hand, in Example 2 of FIG. 6, the assistable power (100) exceeds the required power (70), and thus the required power is a power (120) that is equal to or higher than the assistable power (100) as shown in [1]. As described above, the capacity (discharge flow rate) of the second hydraulic pump 15 is increased and all assistable power (100) is set as assist power.

  And the controller 13 controls the capacity | capacitance of the regeneration motor 17 while controlling the high pressure side regeneration valve of the right regeneration valve 50 and the left regeneration valve 51 to a fully open position so that the set assist power may be obtained.

  Next, in the actuator regeneration process of step S8, the regeneration flow rate and the discharge flow rate of the second hydraulic pump 15 are set.

  Since the assist power is set with priority over the regenerative flow rate as described above, the discharge flow rate of the second hydraulic pump 15 is maintained at a higher level than in the case of the two-type combined operation. For this reason, the power that is borne by the regenerative flow rate among the required power of the second hydraulic pump 15 may be limited.

  Specifically, in Example 1 of FIG. 5, the regenerative flow rate is set to a flow rate for bearing the power (30) obtained by subtracting the assist power (40) from the required power (70). In addition, a flow rate obtained by subtracting the regenerative flow rate from the discharge flow rate of the second hydraulic pump 15 determined by the operation amounts of the arm operation unit 29 and the turning operation unit 33 is set as the discharge flow rate of the second hydraulic pump 15. Note that the operation amount of the turning operation means 33 is 0 as described above in the state during the three-type combined operation.

  On the other hand, in Example 2 of FIG. 6, the regenerative flow rate is set to a flow rate for bearing the power (20) obtained by subtracting the assist power (100) from the required power (120). Further, a flow rate obtained by subtracting the regenerative flow rate from the discharge flow rate determined by the increased capacity of the second hydraulic pump 15 in step S <b> 7 is set as the discharge flow rate of the second hydraulic pump 15.

  Then, the controller 13 controls the arm regenerative valve 40 so as to achieve the set regenerative flow rate, and controls the capacity of the second hydraulic pump 15 so as to achieve the set discharge flow rate.

  Next, in the accumulator regenerative control in step S9, the pressure accumulation flow rate is set.

  As a result, in Example 1 of FIG. 5, the power (70) excluding the power (30) regenerated by the arm cylinder 10 among the regenerative power (100) of the boom cylinder 9 is distributed to the accumulator 42.

  On the other hand, in Example 2 of FIG. 6, the power (80) excluding the power (20) regenerated by the arm cylinder 10 among the regenerative power (100) of the boom cylinder 9 is distributed to the accumulator 42.

  When there is power that cannot be guided to both the arm cylinder 10 and the accumulator 42 in the regenerative power (100), the meter-out flow rate through the M / O valve 46 is also set in step S7.

  Then, based on the pressure accumulation flow and meter-out flow set as described above, the ACC pressure accumulation valve 43 and the M / O valve 46 are controlled, and the process returns.

  Hereinafter, the comparison control and the first embodiment will be compared with reference to FIGS. 5 and 6. The comparative control is an example of control for setting the assist power in a state where the regenerative flow rate is subtracted from the discharge flow rate of the second hydraulic pump 15 determined by the operation amounts of the arm operation unit 29 and the turning operation unit 33.

  In the case of FIG. 5, in the comparative control, the power (50) distributed from the boom cylinder 9 to the arm cylinder 10 is set according to the pressure difference between the primary side and the secondary side of the arm regenerative valve 40 in [1]. The Then, the capacity (required power) of the second hydraulic pump 15 is reduced by the amount of the distributed power (50) (the required power (70) is reduced to the required power (20)).

  In the comparison control, power (50) other than the power (50) distributed to the arm cylinder 10 in [2] is stored in the accumulator 42.

  In this state, since the assist power (20) is set in [3], the power (20) other than the requested power (20) in the assistable power (40) is discarded.

  On the other hand, in Example 1 of the first embodiment, the assistable power (40) is smaller than the required power (70) as described above. Therefore, in [1], all of the assistable power (40) is used as the assist power. Can be used. As a result, the discard power (20) in the comparison control can be effectively used.

  On the other hand, in Example 1 of the first embodiment, the discharge flow rate of the second hydraulic pump 15 is maintained larger than the comparative control by the amount of the waste power (20) (the primary side and the secondary side of the arm regenerative valve 40). Pressure difference with the side is kept small). Therefore, as shown in [2], the power (30) borne by the regenerative flow return oil is more limited than the power (50) borne by the regenerative flow rate in the comparison control, but Example 1 of the first embodiment. The power (70) including the power (20) limited as described above is accumulated in the accumulator 42 as shown in [3].

  Furthermore, in Example 1 of the first embodiment, the required power of the second hydraulic pump 15 is reduced by the amount of power (30) borne by the regenerative flow return oil in [3] (the required power is 70 to 40). Reduced).

  On the other hand, in the case of FIG. 6, in the comparative control, the power (50) distributed from the boom cylinder 9 to the arm cylinder 10 is set according to the pressure difference between the primary side and the secondary side of the arm regenerative valve 40 in [1]. Is done. Then, the capacity (required power) of the second hydraulic pump 15 is reduced by the amount of the distributed power (50) (the required power (70) is reduced to the required power (20)).

  In the comparison control, power (50) other than the power (50) distributed to the arm cylinder 10 in [2] is stored in the accumulator 42.

  Since the assist power (20) is set in [3] in this state, the power (80) other than the requested power (20) in the assistable power (100) is discarded.

  On the other hand, in Example 2 of the first embodiment, as described above, all of the assistable power (100) in [1] is used as the assist power, and one of the discarded power (80) in the comparative control is used. The power (30) of the part can be used effectively.

Specifically, in Example 2 of the first embodiment, the required power (70) increases to the required power (120) in [1]. Therefore, of the energy of the hydraulic oil discharged from the second hydraulic pump 15, the energy corresponding to the increased power (50) from the original required power (70) is the heat when passing through the relief valve (not shown). As discarded. That is, the power (30) obtained by subtracting the increased power (50) from the waste power (80) for comparison control is effectively used. Further, in this state, since the required power is increased so as to be a power that can absorb all of the assistable power (100), the engine 16 blows up when all of the assistable power (100) is used. Can be prevented. In here, the example 2 of the first embodiment, the delivery rate of the hydraulic pump is maintained high (pressure difference between the primary side and the secondary side of the arm the regenerative valve 40 is kept small) than the comparative control. Therefore, as shown in [2], the power (20) borne by the regenerative flow return oil is more limited than the power (50) borne by the regenerative flow return oil in the comparison control. As shown, power (80) including limited power (30) is accumulated in accumulator.

  Furthermore, in Example 2 of the first embodiment, the required flow rate of the second hydraulic pump 15 is reduced by the amount of power (20) borne by the regenerative flow return oil in [3] (the required flow rate is 120 to 100). Reduced).

  As described above, since the regeneration using the return oil from the swing motor 3a is performed with priority over the regeneration using the return oil from the boom cylinder 9, the discharge flow rate of the second hydraulic pump 15 according to the regeneration flow rate. The assist power can be increased as compared with the case where the assist power regenerated by the return oil from the turning motor 3a is set in a state in which is reduced. Therefore, the inertial energy of the upper swing body 3 can be used effectively.

  Here, when the assist power increases, the discharge flow rate of the second hydraulic pump 15 is maintained in a larger state than in the case of the two-type combined operation. For this reason, of the required power required for the second hydraulic pump 15, the power borne by the regenerative flow rate may be limited. However, the hydraulic oil from the head side chamber is not limited to the discharge passage of the second hydraulic pump 15. Supply to the accumulator 42 is also possible.

  Therefore, the regenerative flow and the accumulated flow are specified in a state where the motor regenerative circuit 23 is switched to the permissible state (the right regenerative valve 50 or the left regenerative valve 51) (the state where the assist power is regenerated). As a result, the hydraulic oil whose supply to the discharge passage side is restricted among the return oil from the boom cylinder 9 can be guided to the accumulator 42, and the potential energy of the boom 6 can also be effectively utilized.

  Therefore, sufficient regeneration efficiency can be obtained by effectively utilizing the potential energy of the boom 6 and the inertial energy of the upper swing body 3 during the three-type combined operation.

  Moreover, according to 1st Embodiment, there can exist the following effects.

  As shown in Example 2 of FIG. 6, when the assistable power exceeds the required power, the capacity of the second hydraulic pump 15 is increased so that the required power becomes equal to or higher than the assistable power. When used, it is possible to prevent the engine 16 from blowing up.

  On the other hand, the regenerative flow rate is further limited as the capacity of the second hydraulic pump 15 is increased as described above. By setting the accumulated pressure flow rate based on the increased required power, the return oil from the boom cylinder 9 is reduced. Among them, the hydraulic oil whose supply to the discharge passage is restricted can be guided to the accumulator 42.

  On the other hand, as shown in Example 1 in FIG. 5, when the power (assist power) regenerated by the regenerative motor 17 is less than the required power, a flow rate obtained by subtracting the regenerative flow rate from the discharge flow rate of the second hydraulic pump 15 is obtained. By reducing the capacity of the second hydraulic pump 15, the power of the engine 16 can be reduced.

Second Embodiment
In the first embodiment, the engine 16 is prevented from being blown up by increasing the capacity of the second hydraulic pump 15 so that the required power becomes equal to or higher than the assistable power, but the assistable power exceeds the required power. In addition, it is possible to prevent the engine 16 from blowing up by controlling the regenerative motor 17 so that the assist power is less than or equal to the required power. Specifically, for example, as shown in the second embodiment in FIG. 6, the engine 16 can be prevented from being blown up by limiting the assist power to the power (70) equivalent to the required power.

  In this case, since all of the required power (70) is covered by the assist power, the power that is borne by the return oil of the regenerative flow rate becomes 0, and all of the regenerative power (100) is distributed to the accumulator 42.

  According to the second embodiment, when the assistable power exceeds the required power, the engine 16 can be prevented from being blown up by adjusting the assist power to be equal to or less than the required power.

  Further, according to the second embodiment, it is possible to reduce the capacity of the regenerative motor 17, that is, to reduce the size, as compared with the case where a large-capacity regenerative motor capable of absorbing all possible assistable power is adopted. it can.

  In addition, this invention is not limited to the said embodiment, For example, the following aspects can also be employ | adopted.

  In the above embodiment, a hydraulic excavator is cited as an example of a construction machine. However, the construction machine is not limited to a hydraulic excavator, and may be a crane, a crusher, or a hybrid construction machine having a generator motor.

  Although the arm 7 is mentioned as an example of the driven body, the driven body is not limited to the arm 7 and may be, for example, a bucket or a crawler. Similarly, the hydraulic actuator is not limited to the arm cylinder 10 and may be a bucket cylinder 11 and a travel motor.

  Although the rod side passage of the arm cylinder 10 is cited as an example of the discharge passage of the second hydraulic pump 15, the discharge passage is not limited to the rod side passage, and may be the primary side passage of the control valve 28. The same applies when a hydraulic actuator other than the arm cylinder 10 is employed.

  The regenerative valves 50 and 51 employ flow-adjustable valves that can be switched between a state where the supply of hydraulic oil from the swing motor 3a to the regenerative motor 17 is allowed and a state where it is prohibited. That's fine.

1 Hydraulic excavator (an example of construction machinery)
2 Lower body (an example of lower body)
3 Upper swing body 3a Swing motor 6 Boom 7 Arm (an example of a driven body)
9 Boom cylinder 10 Arm cylinder (example of hydraulic actuator)
13 Controller 15 Second hydraulic pump (an example of a hydraulic pump)
16 Engine 17 Regenerative motor 21 Arm regenerative circuit 22 Accumulator regenerative circuit 23 Motor regenerative circuit

Claims (4)

A hydraulic control device for a construction machine, comprising: a lower body; an upper swing body that is pivotably provided on the lower body; and a boom that is rotatably attached to the upper swing body in an upward direction and a downward direction. There,
A turning motor for driving the upper turning body to turn;
A boom cylinder for driving the boom;
A hydraulic actuator for driving a driven body provided in the construction machine;
A variable displacement hydraulic pump that supplies hydraulic oil to the hydraulic actuator;
An engine for driving the hydraulic pump;
An actuator regenerative circuit provided between the head side chamber of the boom cylinder and the discharge passage of the hydraulic pump, and capable of adjusting the flow rate of hydraulic oil from the head side chamber to the discharge passage;
An accumulator,
An accumulator regenerative circuit that is provided between the head side chamber of the boom cylinder and the accumulator, and is capable of adjusting a flow rate of hydraulic oil from the head side chamber to the accumulator;
A regenerative motor connected to the drive shaft of the engine;
A motor regeneration circuit that is provided between the regenerative motor and the swing motor and is switchable between a permitted state and a prohibited state in which hydraulic oil is allowed to be supplied from the swing motor to the regenerative motor;
With a controller,
The controller is
The actuator regeneration circuit is controlled based on the regenerative flow rate that can be supplied from the head side chamber to the discharge passage during the two-type combined operation of the boom lowering operation and the operation of the driven body, and the accumulator is controlled from the head side chamber. While controlling the accumulator regenerative circuit based on the accumulated pressure flow rate that can be supplied to, and further reducing the capacity of the hydraulic pump so as to obtain a flow rate obtained by subtracting the regenerative flow rate from the discharge flow rate of the hydraulic pump,
Oite during turning deceleration of the upper rotating body, and switching control of the motor regenerative circuit to the allowing state,
In the three composite operation of the the lowering operation of the prior Symbol boom and the operation of the driven member and the pivot deceleration of the upper rotating body is carried out simultaneously, the motor regenerative circuit wherein by switching control to the allowable state, and in this state Identifying the regenerative flow rate and the accumulated pressure flow rate, and further controlling the actuator regeneration circuit and the accumulator regenerative circuit based on the identified regenerative flow rate and the accumulated pressure flow rate,
Hydraulic control device for construction machinery.   The controller is configured to provide the required power when the assistable power that can be borne by using all the hydraulic oil derived from the swing motor exceeds the required power required for the hydraulic pump during the three-type combined operation. The hydraulic control device for a construction machine according to claim 1, wherein the capacity of the hydraulic pump is increased so that is greater than the assistable power. The regenerative motor is a variable capacity motor,
The controller is configured to regenerate the motor when assistable power that can be borne by using all the hydraulic oil derived from the swing motor exceeds the required power required for the hydraulic pump during the three-type combined operation. The hydraulic control device for a construction machine according to claim 1, wherein the regenerative motor is controlled so that the power regenerated by the power becomes equal to or less than the required power.   When the power regenerated by the regenerative motor is smaller than the required power during the three-type combined operation, the controller is configured to obtain the flow rate obtained by subtracting the regenerative flow rate from the discharge flow rate of the hydraulic pump. The hydraulic control device for a construction machine according to any one of claims 1 to 3, wherein a capacity of the pump is reduced.

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