CN104930024B - The control system of hybrid construction machine - Google Patents

Abstract

A control system (100) for a hybrid construction machine includes: a circuit system (S1, S2) that supplies and discharges working oil supplied from a main pump (MP1, MP2) to an actuator through a neutral flow path (6, 18); The operating valves (1~5, 14~17); the main relief valve (8, 19), which is used to keep the working oil pressure of the neutral flow path (6, 18) below the main relief pressure; the passage (55 , 56), which branch between the autonomous pumps (MP1, MP2) and the operating valves (1~5, 14~17); the regenerative motor (M), which uses the working oil guided through the passages (55, 56) to rotate; And regeneration channel switching valves (57, 58), which can open and close the channels (55, 56), when the working oil pressure of the neutral flow channel (6, 18) reaches lower than the main relief pressure during the operation of the actuator When the set pressure is set, the regeneration channel switching valves (57, 58) are switched to the open position with the working oil pressure as the pilot pressure.

Description

Control systems for hybrid construction machines

technical field

The invention relates to a control system of a hybrid power construction machine.

Background technique

Conventionally, there is known a hybrid construction machine that rotates a hydraulic motor using hydraulic fluid guided from an actuator to regenerate energy.

In Japanese JP2009-287745A, a hybrid construction machine is disclosed, which includes a boom cylinder and a swing motor. The working oil guided by the swing motor rotates the hydraulic motor and regenerates energy.

However, in the hybrid construction machine described in JP2009-287745A, when actuators other than the boom cylinder and the swing motor are operated, the remaining hydraulic energy cannot be regenerated.

Contents of the invention

An object of the present invention is to provide a control system for a hybrid construction machine capable of regenerating surplus hydraulic energy even when an actuator other than a boom cylinder or a swing motor is operated.

According to a certain aspect of the present invention, a control system of a hybrid construction machine includes: a circuit system having an operation valve for supplying and discharging working fluid supplied from a main pump through a main passage to an actuator; a main relief valve having a working fluid pressure for maintaining the main passage below a main relief pressure; a regeneration passage branching from a portion of the main passage between the main pump and the operation valve; a regenerative motor for regeneration , which is rotated by the working fluid guided through the regeneration passage; and a regeneration passage switching valve, which can open and close the regeneration passage, when the working fluid pressure of the main passage reaches When the set pressure is lower than the main relief pressure, the regeneration passage switching valve is switched to an open position using the working fluid pressure as a pilot pressure.

Description of drawings

FIG. 1 is a circuit diagram of a control system of a hybrid construction machine according to an embodiment of the present invention.

detailed description

Hereinafter, a control system 100 for a hybrid construction machine according to an embodiment of the present invention will be described with reference to the drawings.

First, with reference to FIG. 1 , an overall configuration of a control system 100 for a hybrid construction machine will be described. Here, a case where the hybrid construction machine is a hydraulic excavator will be described. In hydraulic excavators, working oil is used as a working fluid.

The hydraulic excavator includes a first main pump MP1 and a second main pump MP2 that discharge working oil to drive each actuator, a first circuit system S1 that supplies working oil from the first main pump MP1, and a first circuit system that supplies working oil from the second main pump MP2. The second circuit system S2 of working oil.

The first main pump MP1 and the second main pump MP2 are variable displacement pumps capable of adjusting the deflection angle of the swash plate. The engine E drives the first main pump MP1 and the second main pump MP2 to rotate coaxially.

The first circuit system S1 includes an operating valve 1 for controlling the swing motor RM, an operating valve 2 for controlling the arm cylinder (not shown), and an operating valve 2 for controlling the boom cylinder BC as a fluid pressure cylinder in order from the upstream side. The operating valve 3 for the two-speed boom, the operating valve 4 for controlling the auxiliary accessories (not shown) such as the breaker (Japanese: ブレーカ) and the breaker, and the first driving motor for controlling the left driving ( (illustration omitted) operates the valve 5.

Each of the operation valves 1 to 5 controls the flow rate of hydraulic oil guided from the first main pump MP1 to each actuator, thereby controlling the operation of each actuator. Each of the operation valves 1 to 5 is operated by a pilot pressure supplied as the operator of the hydraulic excavator manually operates the operation lever.

Each of the operation valves 1 to 5 is connected to the first main pump MP1 via the neutral flow passage 6 and the parallel passage 7 which are main passages connected in parallel to each other. A main relief valve 8 is provided at the upstream side of the operating valve 1 in the neutral flow path 6, and if the working oil pressure in the neutral flow path 6 exceeds a predetermined main relief pressure, the main relief valve 8 opens and Keep the working oil pressure below the predetermined main relief pressure. The predetermined main relief pressure is set high enough to sufficiently secure the minimum operating pressure of each of the operation valves 1 to 5 .

An orifice 9 for generating a pilot pressure (negative pilot pressure) is provided at a position downstream of the operation valve 5 in the neutral flow path 6 . If the passing flow rate is large, the throttle member 9 generates a high pilot pressure on the upstream side, and if the passing flow rate is small, the throttle member 9 generates a low pilot pressure on the upstream side.

A pilot overflow valve 10 is provided in parallel with the throttling element 9. If the pilot pressure generated on the upstream side of the throttling element 9 exceeds a predetermined pilot relief pressure, the pilot relief valve 10 opens and maintains the pilot pressure at a predetermined value. below the pilot relief pressure. In addition, the predetermined pilot relief pressure is set to be lower than the main relief pressure of the main relief valve 8 to such an extent that the throttle member 9 does not generate abnormal pressure.

The neutral flow path 6 guides all or part of the hydraulic oil discharged from the first main pump MP1 to the oil tank T when all of the operation valves 1 to 5 are located at or near the neutral position. In this case, the flow rate of hydraulic oil passing through the throttle 9 is increased, so a high pilot pressure is generated.

On the other hand, when the operation valve 1 to the operation valve 5 are switched to the full stroke, the neutral flow path 6 is closed and the circulation of the hydraulic oil disappears. In this case, the flow rate of hydraulic oil passing through the throttle 9 is almost eliminated, and the pilot pressure is kept at zero. However, according to the operation amount of the operation valve 1 to the operation valve 5, a part of the hydraulic fluid discharged from the first main pump MP1 is guided to the actuator, and the rest is guided to the oil tank T from the neutral flow path 6, so the throttle 9 generates a pilot pressure corresponding to the flow rate of hydraulic oil in the neutral flow path 6 . That is, the throttle 9 generates a pilot pressure corresponding to the operation amount of the operation valve 1 to the operation valve 5 .

A pilot flow path 11 is connected to the upstream side of the throttle body 9 . The pilot pressure generated by the throttle 9 is guided to the pilot flow path 11 . The pilot flow path 11 is connected to a regulator 12 for controlling the displacement (deflection angle of the swash plate) of the first main pump MP1.

The regulator 12 controls the deflection angle of the swash plate of the first main pump MP1 in direct proportion to the pilot pressure of the pilot flow path 11 (the proportionality constant is a negative number), and controls each rotation of the first main pump MP1 (Japanese: one turn)あたり) displacement. Therefore, the operation valve 1 to the operation valve 5 are switched to the full stroke and the flow of hydraulic oil passing through the orifice 9 disappears, and when the pilot pressure of the pilot passage 11 becomes zero, the deflection of the swash plate of the first main pump MP1 Maximum angle and maximum displacement per rotation.

A pressure sensor 13 for detecting the pressure of the pilot flow path 11 is provided on the pilot flow path 11 . The pressure signal detected by the pressure sensor 13 is output to the controller C. The pilot pressure of the pilot flow path 11 changes according to the operation amount of the operation valve 1 to the operation valve 5 . Therefore, the pressure signal detected by the pressure sensor 13 is proportional to the required flow rate of the first circuit system S1.

The second circuit system S2 includes an operating valve 14 for controlling a second traveling motor (not shown) for right traveling, an operating valve 15 for controlling a bucket cylinder (not shown), An operation valve 16 for controlling the boom cylinder BC and an operation valve 17 for two-speed arm for controlling the arm cylinder (not shown in the figure) are provided.

Each of the operation valves 14 to 17 controls the flow rate of hydraulic fluid guided from the second main pump MP2 to each actuator, and controls the operation of each actuator. Each of the operation valves 14 to 17 is operated by a pilot pressure supplied as the operator of the hydraulic excavator manually operates the operation lever.

Each of the operation valves 14 to 17 is connected to the second main pump MP2 via a neutral flow path 18 serving as a main passage. In addition, each of the operation valves 14 to 16 is connected to the second main pump MP2 via a parallel passage 29 parallel to the neutral flow passage 18 . On the upstream side of the operating valve 14 in the neutral flow path 18, a main relief valve 19 is provided. If the pressure of the working oil in the neutral flow path 18 exceeds the predetermined main relief pressure, the main relief valve 19 will open and release the working oil. The pressure remains below the main overflow pressure. The predetermined main relief pressure is set high enough to sufficiently ensure the minimum operating pressure of each of the operation valves 14 to 17 .

In addition, the main relief valves 8 and 19 only need to be provided in at least any one of the first circuit system S1 and the second circuit system S2. In the case where the main relief valve is only provided in one of the first circuit system S1 and the second circuit system S2, the circuit is connected so that the working oil is also supplied from the other of the first circuit system S1 and the second circuit system S2. or lead to the same main relief valve. In this way, when a single main relief valve is provided, the main relief valve is shared by the first circuit system S1 and the second circuit system S2.

An orifice 20 for generating a pilot pressure (negative pilot pressure) is provided at a position downstream of the operation valve 17 in the neutral flow path 18 . The throttle valve 20 has the same function as the throttle 9 on the first main pump MP1 side.

In parallel with the throttle member 20, there is provided a pilot relief valve 21, which opens and maintains the pilot pressure when the pilot pressure generated on the upstream side of the throttle member 20 exceeds a predetermined pilot relief pressure Below the predetermined pilot relief pressure. In addition, the predetermined pilot relief pressure is set to be lower than the main relief pressure of the main relief valve 19 to such an extent that the throttle member 20 does not generate an abnormal pressure.

A pilot flow path 22 is connected to the upstream side of the throttle 20 , and the pilot pressure generated by the throttle 20 is guided to the pilot flow path 22 . The pilot flow path 22 is connected to a regulator 23 for controlling the displacement (deflection angle of the swash plate) of the second main pump MP2.

The regulator 23 controls the deflection angle of the swash plate of the second main pump MP2 in direct proportion to the pilot pressure of the pilot passage 22 (the proportionality constant is a negative number), and controls the displacement per rotation of the second main pump MP2. Therefore, the operation valve 14 to the operation valve 17 are switched to the full stroke so that the flow of hydraulic oil passing through the orifice 20 disappears, and when the pilot pressure of the pilot flow path 22 becomes zero, the deflection of the swash plate of the second main pump MP2 Maximum angle and maximum displacement per rotation.

A pressure sensor 24 for detecting the pressure of the pilot flow path 22 is provided on the pilot flow path 22 . The pressure signal detected by the pressure sensor 24 is output to the controller C. The pilot pressure of the pilot flow path 22 changes according to the operation amount of the operation valve 14 - the operation valve 17 . Therefore, the pressure signal detected by the pressure sensor 24 is proportional to the required flow rate of the second circuit system S2.

The engine E is provided with a generator 25 that generates electricity using a surplus power of the engine E. As shown in FIG. Electric power generated by the generator 25 is charged into the battery 27 via the battery charger 26 . The battery charger 26 can charge the battery 27 with electric power even when it is connected to a general household power supply 28 .

Next, the rotary motor RM will be described.

The swing motor RM is provided in the swing circuit 30 for driving the swing motor RM. The swing circuit 30 includes a pair of supply and discharge passages 31, 32 connecting the first main pump MP1 and the swing motor RM and having an operating valve 1, and relief valves respectively connected to the supply and discharge passages 31, 32 and opened under a set pressure. 33, 34.

The operation valve 1 is a three-way switching valve. When the operation valve 1 is in the neutral position, the actuator port of the operation valve 1 is closed, so the supply and discharge of hydraulic oil to the rotary motor RM is blocked, and the rotary motor RM remains in a stopped state.

When the operation valve 1 is switched to one position, the supply and discharge passage 31 is connected to the first main pump MP1, and the supply and discharge passage 32 communicates with the tank T. As a result, the rotary motor RM is rotated by supplying hydraulic oil through the supply/drain passage 31 , and the return hydraulic oil from the rotary motor RM is discharged to the oil tank T via the supply/drain passage 32 . On the other hand, when the operation valve 1 is switched to another position, the supply and discharge passage 32 is connected to the first main pump MP1, and the supply and discharge passage 31 communicates with the oil tank T, so that the rotary motor RM rotates in the reverse direction.

When the rotary motor RM rotates, when the rotary pressure of the supply and discharge passages 31, 32 reaches the set pressure of the relief valves 33, 34, the relief valves 33, 34 are opened so that the remaining flow on the high pressure side is directed to the low pressure side.

During the turning operation of the turning motor RM, if the operating valve 1 is switched to the neutral position, the actuator port of the operating valve 1 is closed. Thus, a closed circuit is formed by the supply and discharge passages 31 , 32 , the swing motor RM, and the relief valves 33 , 34 . In this way, even if the actuator for operating the valve 1 is closed, the rotary motor RM can continue to rotate by using inertial energy to function as a pump.

Accordingly, one of the supply and discharge passages 31 and 32 that is at low pressure during the swivel operation becomes high pressure, and the other of the supply and discharge passages 31 and 32 that is at high pressure during the swivel operation becomes low pressure. Therefore, a braking force acts on the turning motor RM to perform a braking operation. At this time, when the brake pressure of the supply and discharge passages 31, 32 reaches the set pressure of the relief valves 33, 34, the relief valves 33, 34 are opened so that the brake flow of the high pressure side is guided to the low pressure side.

When the rotary motor RM is braked, if the suction flow rate of the rotary motor RM is insufficient, the operating oil in the oil tank T passes through the check valves 35 and 36 that allow only the operating oil to flow from the oil tank T to the supply and discharge passages 31 and 32. be inhaled.

Next, the boom cylinder BC will be described.

The operation valve 16 for controlling the operation of the boom cylinder BC is a three-way switching valve. When the operation valve 16 is switched from the neutral position to one position, the working oil discharged from the second main pump MP2 is supplied to the piston side chamber 39 of the boom cylinder BC through the supply and discharge passage 38, and the return working oil from the rod side chamber 40 is passed through the The supply and discharge passage 37 discharges to the tank T. As shown in FIG. Therefore, boom cylinder BC expands.

On the other hand, if the operation valve 16 is switched to another position, the operating oil discharged from the second main pump MP2 is supplied to the rod side chamber 40 of the boom cylinder BC via the supply and discharge passage 37, and the return operation from the piston side chamber 39 The oil is discharged to the oil tank T through the supply and discharge passage 38 . Therefore, the boom cylinder BC contracts.

When the operation valve 16 is switched to the neutral position, the supply and discharge of hydraulic fluid to the boom cylinder BC is blocked, and the boom remains stopped. In addition, the operation valve 3 for boom two speeds is switched when the operation amount of the operation lever by the operator is greater than a predetermined amount.

When the operation valve 16 is switched to the neutral position and the movement of the boom is stopped, a force in the contracting direction acts on the boom cylinder BC due to the dead weight of the bucket, the arm, the boom, and the like. In this way, the boom cylinder BC is used to hold the load in the piston-side chamber 39 when the operation valve 16 is in the neutral position, and the piston-side chamber 39 serves as a load-side pressure chamber.

The control system 100 of the hybrid construction machine has a regenerative device that performs regenerative control that regenerates energy by recovering energy from hydraulic oil from the swing circuit 30 and the boom cylinder BC. Hereinafter, this playback device will be described.

The regeneration control of the regeneration device is performed by the controller C. The controller C includes a CPU (Central Processing Unit) for performing regeneration control, a ROM (Read Only Memory) that stores control programs, setting values, etc. necessary for the CPU's processing actions, and temporarily stores the data detected by various sensors. information in RAM (Random Access Memory).

First, the turning regeneration control for performing energy regeneration using hydraulic oil from the turning circuit 30 will be described.

Branch passages 41 and 42 are respectively connected to the supply and discharge passages 31 and 32 connected to the rotary motor RM. The branch passages 41 and 42 join together and are connected to a turning regeneration passage 43 for guiding hydraulic fluid from the turning circuit 30 to the regenerative motor M for regeneration. The branch passages 41 and 42 are respectively provided with one-way valves 44 and 45 which allow only hydraulic fluid to flow from the supply and discharge passages 31 and 32 to the turning regeneration passage 43 . The turning regenerative passage 43 is connected to the regenerative motor M via a confluence regeneration passage 46 .

The regenerative motor M is a variable capacity motor capable of adjusting the deflection angle of the swash plate, and is connected so as to rotate coaxially with an electric motor 47 serving as a rotating electric machine that also serves as a generator. The regenerative motor M is driven by hydraulic fluid discharged from the swing motor RM and the boom cylinder BC through the junction regenerative passage 46 . The regenerative motor M can drive the electric motor 47 . When the electric motor 47 functions as a generator, electric power generated by the electric motor 47 is charged into the battery 27 via the inverter 48 . The regenerative motor M and the electric motor 47 may be directly connected or may be connected via a speed reducer.

Upstream of the regenerative motor M is connected an upward suction passage 78. When the supply of operating oil to the regenerative motor M is insufficient, the upward suction passage 78 sucks the operating oil from the oil tank T into the confluence regeneration passage 46 and supplies it to the regenerative motor M. supply. A check valve 78 a that allows only hydraulic fluid to flow from the oil tank T to the confluence regeneration passage 46 is provided in the suction passage 78 .

A pressure sensor 79 as a pressure detector for detecting the pressure of hydraulic oil downstream of the check valve 78 a is provided in the suction passage 78 . The pressure sensor 79 detects the pressure of hydraulic oil supplied to the regenerative motor M. As shown in FIG.

An electromagnetic switch valve 49 that is switched and controlled based on a signal output from the controller C is provided in the swing regeneration passage 43 . A pressure sensor 50 for detecting a turning pressure during a turning operation of the turning motor RM or a braking pressure during a braking operation is provided between the electromagnetic switching valve 49 and the check valves 44 and 45 . The pressure signal detected by the pressure sensor 50 is output to the controller C.

The electromagnetic switching valve 49 is set to the closed position (the state shown in FIG. 1 ) when the solenoid is not excited, thereby blocking the rotation regeneration passage 43 . The electromagnetic switching valve 49 is switched to the open position when the solenoid is energized, thereby opening the swing regeneration passage 43 . The electromagnetic switching valve 49 guides the hydraulic fluid from the rotary circuit 30 to the regenerative motor M when switched to the open position. Thus, rotation regeneration is performed.

Here, the path of hydraulic fluid from the rotary circuit 30 to the regenerative motor M will be described. For example, when the rotary motor RM rotates with hydraulic oil supplied through the supply and discharge passages 31 and 32 , the remaining oil in the supply and discharge passages 31 and 32 flows in through the branch passages 41 and 42 and the check valves 44 and 45 . The regenerative passage 43 is rotated and guided to the regenerative motor M. In addition, when the turning motor RM is turned by the working oil supplied through the supply and discharge passages 31 and 32, when the brake operation is performed to switch the operation valve 1 to the neutral position, the working oil discharged by the pump action of the turning motor RM passes through the The branch passages 41 and 42 and the check valves 44 and 45 flow into the turning regeneration passage 43 and are guided to the regeneration motor M. As shown in FIG.

A relief valve 51 is provided at a position downstream of the electromagnetic switching valve 49 in the swing regeneration passage 43 . The safety valve 51 maintains the pressure of the branch passages 41 and 42 and prevents the swing motor RM from running away when, for example, an abnormality occurs in the electromagnetic switching valve 49 of the swing regeneration passage 43 .

The controller C excites the solenoid of the electromagnetic switching valve 49 when it determines that the pressure detected by the pressure sensor 50 is equal to or higher than the turning regeneration start pressure. As a result, the electromagnetic switching valve 49 is switched to the open position to start the swing regeneration.

When the controller C determines that the pressure detected by the pressure sensor 50 is lower than the turning regeneration start pressure, it de-energizes the solenoid of the electromagnetic switching valve 49 . As a result, the electromagnetic switching valve 49 is switched to the closed position to stop the rotation regeneration.

Next, boom regeneration control in which energy is regenerated using hydraulic fluid from the boom cylinder BC will be described.

An electromagnetic proportional throttle valve 52 whose opening is controlled by an output signal from the controller C is provided in the supply/discharge passage 38 connecting the piston side chamber 39 of the boom cylinder BC and the operation valve 16 . The electromagnetic proportional throttle valve 52 maintains a fully open position under normal conditions.

A boom regeneration passage 53 branched from between the piston side chamber 39 and the electromagnetic proportional throttle valve 52 is connected to the supply and discharge passage 38 . The boom regeneration passage 53 is a passage for guiding return hydraulic oil from the piston side chamber 39 to the regenerative motor M. As shown in FIG. The turning regeneration passage 43 merges with the boom regeneration passage 53 and is connected to the merged regeneration passage 46 .

The boom regeneration passage 53 is provided with an electromagnetic switching valve 54 that is switched and controlled by a signal output from the controller C. As shown in FIG. The electromagnetic switching valve 54 is switched to the closed position (state shown in FIG. 1 ) when the solenoid is not excited, and the boom regeneration passage 53 is blocked. The electromagnetic switching valve 54 is switched to the open position when the solenoid is energized, and the boom regeneration passage 53 is opened to allow only hydraulic fluid to flow from the piston side chamber 39 to the junction regeneration passage 46 .

The operation valve 16 is provided with a sensor (not shown) for detecting the operation direction and the operation amount of the operation valve 16 . Signals detected by the sensors are output to the controller C. The controller C calculates the expansion and contraction direction and the expansion and contraction amount of the boom cylinder BC based on the operation direction and the operation amount of the operation valve 16 detected by the sensor.

In addition, instead of the above sensors, a sensor for detecting the moving direction and the moving amount of the piston rod may be provided on the boom cylinder BC, or a sensor for detecting the operating direction and the operating amount may be provided on the control rod. .

The controller C determines whether the operator intends to expand or contract the boom cylinder BC based on the detection result of the sensor. When the controller C determines that the boom cylinder BC is extending, it keeps the electromagnetic proportional throttle valve 52 at the fully open position in the normal state, and keeps the electromagnetic switching valve 54 at the closed position.

On the other hand, when the controller C determines that the boom cylinder BC is contracting, it calculates the contraction speed of the boom cylinder BC requested by the operator according to the operation amount of the operation valve 16, and closes the electromagnetic proportional throttle valve 52. And switch the electromagnetic switching valve 54 to the open position. As a result, all return hydraulic fluid from the boom cylinder BC is guided to the regenerative motor M to perform boom regeneration.

When the flow rate consumed by the regenerative motor M is less than the flow rate required to maintain the contraction speed of the boom cylinder BC requested by the operator, the controller C, according to the operation amount of the operation valve 16, the deflection angle of the swash plate of the regenerative motor M and the rotation speed of the electric motor 47 etc. to control the opening of the electromagnetic proportional throttle valve 52 so that the flow exceeding the flow consumed by the regenerative motor M returns to the tank T. Accordingly, the retraction speed of the boom cylinder BC requested by the operator is maintained.

When the swing motor RM is turned and the boom cylinder BC is lowered, the return hydraulic oil from the swing motor RM and the return hydraulic oil from the boom cylinder BC are merged in the merge regeneration passage 46 and supplied to the regeneration motor M. .

At this time, even if the pressure of the swing regeneration passage 43 rises and is higher than the swing pressure or brake pressure of the swing motor RM, since the working oil in the swing regeneration passage 43 is prevented from backflow by the check valves 44 and 45, it is not supplied to the swing motor RM. RM makes an impact. In addition, if the pressure in the swing regeneration passage 43 decreases and is lower than the swing pressure or the brake pressure, the controller C closes the electromagnetic switching valve 49 according to the pressure signal from the pressure sensor 50 .

Therefore, when the turning operation of the turning motor RM and the lowering movement of the boom cylinder BC are performed simultaneously, the deflection of the regenerative motor M is limited based on the lowering speed required by the boom cylinder BC regardless of the turning pressure or the braking pressure. horn.

Next, the residual flow rate regeneration control for recovering the energy of the working oil from the neutral flow paths 6 and 18 and regenerating the energy and utilizing the energy of the working oil from the auxiliary pump SP as the auxiliary pump to the first main pump MP1 and the second main pump will be described. The output of pump MP2 performs auxiliary auxiliary control.

First, the remaining flow rate regeneration control will be described.

The control system 100 of the hybrid construction machine executes surplus flow rate regeneration control for recovering energy from hydraulic oil in the neutral flow paths 6 and 18 to regenerate the energy. The remaining flow rate regeneration control is performed by the controller C in the same manner as the swing regeneration control and the boom regeneration control.

A part of the neutral flow path 6 of the first circuit system S1 on the upstream side of the operation valve 1 is connected to the confluence regeneration path 46 by a path 55 serving as a regeneration path. The passage 55 branches from a portion of the neutral flow passage 6 between the first main pump MP1 and the operation valve 1 and is connected to the confluence regeneration passage 46 . A regeneration passage switching valve 57 capable of opening and closing the passage 55 is provided in the passage 55 .

Similarly, a part of the neutral flow path 18 of the second circuit system S2 on the upstream side of the operation valve 14 is connected to the combined regeneration passage 46 by a passage 56 serving as a regeneration passage. The passage 56 branches from a portion of the neutral flow passage 18 between the second main pump MP2 and the operation valve 14 and is connected to the confluence regeneration passage 46 . A regeneration passage switching valve 58 capable of opening and closing the passage 56 is provided on the passage 56 .

The regeneration passage switching valve 57 is a two-port, two-position spool type switching valve. In the regeneration passage switching valve 57, a pair of pilot chambers 57a and 57b are provided to face one end of a spool (not shown). The slide core is biased in one direction by a return spring 57c provided at the other end of the slide core. The regenerative passage switching valve 57 is normally held in the blocked position (state shown in FIG. 1 ) by the spring force of the return spring 57c.

With the regeneration passage switching valve 57 held at the blocking position, the flow of hydraulic oil from the neutral flow passage 6 to the merge regeneration passage 46 is blocked. When the pilot pressure is supplied to the pilot chamber 57a, the regenerative passage switching valve 57 is switched to the regenerative position (lower position in FIG. When the pilot pressure is supplied, the regenerative passage switching valve 57 switches to the blocking position to close the passage 55 .

The pilot pressure supplied to the pilot chamber 57a is guided from the neutral flow path 6 of the first circuit system S1 via the passage 55 and the pilot passage 55a. When the operating oil pressure in the neutral flow path 6 reaches a set pressure lower than the main relief pressure during the operation of the actuator, the regeneration passage switching valve 57 is switched to the regenerative position with the operating oil pressure as the pilot pressure. In addition, the predetermined set pressure is set to a pressure slightly lower than the main relief pressure of the main relief valve 8 .

On the other hand, the pilot chamber 57b of the regeneration passage switching valve 57 is connected to the oil tank T. As shown in FIG. In the regeneration passage switching valve 57, the pilot pressure is not supplied to the other pilot chamber 57b. The pilot chamber 57b is used to allow the working oil sucked up from the oil tank T to flow out when the regeneration passage switching valve 57 is switched from the regeneration position to the blocking position, or to return the working oil leaked from the clearance of the slide core of the regeneration passage switching valve 57 Components in tank T.

The regeneration passage switching valve 58 is a two-port, two-position, spool-type switching valve. In the regeneration path switching valve 58, a pair of pilot chambers 58a, 58b (first pilot chamber, second pilot chamber) are provided to face one end of a spool (not shown). The slide core is biased in one direction by a return spring 58c provided at the other end of the slide core. The regenerative passage switching valve 58 is normally held in the blocking position (state shown in FIG. 1 ) by the spring force of the return spring 58c.

The regeneration passage switching valve 58 blocks the flow of hydraulic oil from the neutral flow passage 18 to the merge regeneration passage 46 while being held at the blocked position. When the pilot pressure is supplied to either of the pilot chambers 58a, 58b, the regeneration passage switching valve 58 is switched to the regeneration position (the lower position in FIG. 1 ) which is an open position, and the hydraulic oil is allowed to regenerate from the neutral flow path 18 to the combined flow. When the passage 46 flows and the supply of the pilot pressure is blocked, the regenerative passage switching valve 58 is switched to the blocked position and the passage 56 is blocked.

The pilot pressure supplied to the pilot chamber 58a is guided from the neutral flow path 18 of the second circuit system S2 through the passage 56 and the pilot passage 56a. When the operating oil pressure in the neutral flow path 18 reaches a set pressure lower than the main relief pressure during the operation of the actuator, the regenerative passage switching valve 58 is switched to the regenerative position with the operating oil pressure as the pilot pressure. In addition, the predetermined set pressure is set to a pressure slightly lower than the main relief pressure of the main relief valve 19 .

The pilot pressure supplied to the pilot chamber 58 b is supplied from a pilot pump PP as a pilot pressure source via a pilot passage 60 . An electromagnetic proportional pressure reducing valve 62 as an electromagnetic valve capable of outputting a pilot pressure proportional to a command signal from the controller C is provided in the pilot passage 60 . When the solenoid is excited by the command signal output from the controller C, the electromagnetic proportional pressure reducing valve 62 reduces the pilot pressure from the pilot pump PP to a pilot pressure corresponding to the command value, and turns the pilot pressure to the command value. Pilot pressure is supplied to the pilot passage 60 .

As described above, the regenerative passage switching valve 58 can perform internal switching based on the pilot pressure guided from the neutral flow passage 18 to the pilot chamber 58a via the passage 56 and the pilot passage 56a, and can switch from the pilot pump based on the command signal from the controller C. External switching of PP pilot pressure leading to pilot chamber 58b. On the other hand, the regeneration passage switching valve 57 can only perform internal switching based on the pilot pressure guided from the neutral flow passage 6 to the pilot chamber 57a via the passage 55 and the pilot passage 55a.

However, the regeneration passage switching valve 57 is also provided with a pair of pilot chambers 57 a and 57 b similarly to the regeneration passage switching valve 58 . Therefore, the regenerative passage switching valve 57 and the regenerative passage switching valve 58 can be configured in the same manner, thereby enabling cost reduction. In addition, the regenerative passage switching valve 57 can also be configured to be externally switchable in the same way as the regenerative passage switching valve 58 .

Here, in the neutral flow path 18 of the second circuit system S2, a valve that can open and close the neutral flow path 18 is provided at a position downstream of the operation valve 17 and upstream of the connecting portion of the pilot flow path 22. The neutral cut-off valve 63 of the main passage switching valve. When the pilot pressure is supplied to the pilot chamber 63a, the neutral stop valve 63 is switched to the closed position to block the neutral flow path 18, and when the supply of pilot pressure is blocked, the neutral stop valve 63 is switched to the open position to open the neutral flow path 18.

The pilot chamber 63 a of the neutral stop valve 63 is connected to the pilot passage 60 . Therefore, when the pilot pressure is supplied to the pilot chamber 58 b of the regeneration passage switching valve 58 by the electromagnetic proportional pressure reducing valve 62 , the pilot pressure is also supplied to the pilot chamber 63 a of the neutral cut valve 63 at the same time. That is, the neutral cut valve 63 operates in conjunction with the regeneration passage switching valve 58 .

When all the actuators are inactive, the controller C excites the solenoid of the electromagnetic proportional pressure reducing valve 62 . As a result, the pilot pressure is supplied to the pilot chamber 58b of the regeneration passage switching valve 58, and the regeneration passage switching valve 58 is switched to the regeneration position. Then, the hydraulic oil in the neutral flow path 18 is guided to the confluence regeneration path 46 via the path 56, and the surplus flow rate regeneration of the second circuit system S2 is performed. At this time, since the neutral cut valve 63 is switched to the closed position to minimize the transmitted pilot pressure, the regulator 23 controls so that the displacement of the second main pump MP2 becomes the maximum.

When the controller C switches the electromagnetic proportional decompression valve 62 and performs the surplus flow regeneration control, it uses the regulator 66 to adjust the pressure of the swash plate of the regenerative motor M based on the pressure of the hydraulic oil supplied to the regenerative motor M detected by the pressure sensor 79 . The deflection angle is controlled so that the working oil pressure in the neutral flow paths 6 and 18 becomes equal to or higher than the minimum working pressure of the operating valves 1 to 5 and 14 to 17 .

Next, the effect of the remaining flow rate regeneration control will be described.

When the hydraulic oil pressure of the neutral flow path 6 reaches a predetermined set pressure, the regeneration path switching valve 57 connected to the path 55 of the neutral flow path 6 is switched to the regeneration position, and the high-pressure hydraulic oil of the first main pump MP1 is guided to the regeneration position. to regenerative motor M. In addition, when the hydraulic oil pressure of the neutral flow path 18 reaches a predetermined set pressure, the regeneration path switching valve 58 of the path 56 connected to the neutral flow path 18 is switched to the regeneration position, and the high-pressure hydraulic oil of the second main pump MP2 is directed to the regenerative motor M.

Here, in the past, during the operation of the boom cylinder BC and the swing motor RM, energy regeneration can be performed from the excess flow of the boom cylinder BC and the swing motor RM through the boom regeneration control and the swing regeneration control. In the case of actuators other than the arm cylinder BC and the swing motor RM, energy regeneration cannot be performed.

On the other hand, in the present embodiment, for example, when the operating oil pressure in the neutral flow path 6 or the neutral flow path 18 reaches the set pressure while the bucket, arm, etc. 6 or the hydraulic oil remaining in the neutral flow path 18 is discarded from the main relief valve 8 or the main relief valve 19 and guided to the regenerative motor M. Therefore, it is possible to regenerate energy that has been discarded in the past, so energy loss can be reduced and more energy can be regenerated. Therefore, the energy consumption of the whole system can be reduced.

In addition, the backup flow of the neutral flow path 18 can be directed to the regenerative motor M when all actuators are not operating. In this way, backup charging is performed in which the regenerative motor M is rotated using the backup flow rate to generate power, thereby increasing the battery charge amount. In particular, since the neutral stop valve 63 is provided in the neutral flow path 18 of the second circuit system S2, the hydraulic oil pressure in the neutral flow path 18 can be increased to near the main relief pressure. As a result, a higher-pressure surplus flow rate is introduced to the regenerative motor M, and thus the time required to charge the battery 27 to a predetermined battery capacity can be shortened.

Moreover, when the controller C switches the electromagnetic proportional decompression valve 62 and performs surplus flow regeneration control, it uses the regulator 66 to control the deflection angle of the swash plate of the regenerative motor M so that the pressure of the working oil in the neutral flow paths 6 and 18 It is equal to or higher than the minimum working pressure of the operation valve 1 to the operation valve 5 and the operation valve 14 to the operation valve 17 . Thereby, energy regeneration can be performed while maintaining the hydraulic oil pressure in the neutral flow passages 6 and 18 on the side where the hydraulic oil is guided to the regenerative motor M. FIG.

Furthermore, since the neutral stop valve 63 is provided on the upstream side of the pilot relief valve 21, when the hydraulic oil pressure in the neutral flow path 18 reaches the set pressure and the neutral stop valve 63 is switched to the closed position, the neutral stop valve 63 can be prevented from being closed. The hydraulic oil pressure in the flow path 18 is relieved from the pilot relief valve 21 . As a result, a higher hydraulic oil pressure can be supplied to the regenerative motor M during the excess flow rate regeneration control, and thus more energy can be regenerated.

Next, assist control will be described.

The sub pump SP is a variable displacement type pump capable of adjusting the deflection angle of the swash plate, and is connected to the regenerative motor M so as to rotate coaxially. The sub pump SP is rotated by the driving force of the electric motor 47 . The rotational speed of the electric motor 47 is controlled by the controller C via the inverter 48 . The deflection angles of the swash plates of the sub pump SP and the regenerative motor M are controlled by the controller C via the regulators 67 and 66 .

A discharge passage 68 serving as an auxiliary passage is connected to the sub pump SP. The sub pump SP can supply hydraulic oil to the neutral flow paths 6 and 18 via the discharge passage 68 . The discharge passage 68 is branched into a first discharge passage 69 that merges with the passage 55 and a second discharge passage 70 that merges with the passage 56 . A high-pressure selective switching valve 71 serving as an auxiliary switching valve is provided at a branch portion of the discharge passage 68 . The first discharge passage 69 is provided with a check valve 72 that allows only hydraulic fluid to flow from the discharge passage 68 to the passage 55 . Similarly, the second discharge passage 70 is provided with a check valve 73 that allows only hydraulic fluid to flow from the discharge passage 68 to the passage 56 .

The high-pressure selection switching valve 71 is a three-port, three-position, slide-type switching valve. In the high-pressure selective switching valve 71, pilot chambers 71a and 71b are respectively provided to face both ends of a spool (not shown). The working oil in the passage 55 is supplied to one pilot chamber 71 a via the first pilot passage 76 . The working oil in the passage 56 is supplied to the other pilot chamber 71 b via the second pilot passage 77 . A damping orifice 74 is provided in the first pilot passage 76 , and a damping orifice 75 is provided in the second pilot passage 77 . The slide core is supported in a neutral state by a pair of centering springs 71c and 71d respectively provided at both ends. The high pressure selection switching valve 71 is normally held in the normal position (the state shown in FIG. 1 ) by the spring force of the centering springs 71c, 71d.

The high-pressure selection switching valve 71 proportionally distributes and supplies the discharge oil of the sub pump SP to the first discharge passage 69 and the second discharge passage 70 while maintaining the normal position.

When the pilot pressure of one pilot chamber 71a is higher than the pilot pressure of the other pilot chamber 71b, the high pressure selection switching valve 71 is switched to the first switching position (lower position in FIG. 1 ). Accordingly, the discharge oil of the sub pump SP is supplied to the passage 55 .

When the pilot pressure of the other pilot chamber 71b is higher than the pilot pressure of one pilot chamber 71a, the high pressure selection switching valve 71 is switched to the second switching position (upper position in FIG. 1 ). Accordingly, the discharge oil of the sub pump SP is supplied to the passage 56 .

That is, the high-pressure selection switching valve 71 selects one of the passage 55 and the passage 56 with high pressure, and supplies the discharge oil of the sub pump SP. In addition, while the high-pressure selective switching valve 71 is switching, hydraulic fluid is supplied to both the passage 55 and the passage 56, but when the difference between the pilot pressure of one of the pilot chambers 71a, 71b and the pilot pressure of the other When the differential pressure is sufficiently large, all of the discharge oil from the sub pump SP is supplied to the high-pressure side of the passage 55 and the passage 56, and is not supplied to the low-pressure side at all.

When the sub pump SP rotates by the driving force of the electric motor 47, the sub pump SP assists the output of at least one of the first main pump MP1 and the second main pump MP2. Which one of the first main pump MP1 and the second main pump MP2 is to be assisted is determined by the high-pressure selection switching valve 71 , and automatic assisted operation that does not require the control of the controller C is performed.

When hydraulic oil is supplied to the regenerative motor M through the confluent regenerative passage 46 and the regenerative motor M rotates, the rotational force of the regenerative motor M acts as an assist force for the coaxially rotating electric motor 47 . Therefore, the power consumption of the electric motor 47 can be reduced by a portion corresponding to the rotational force of the regenerative motor M. FIG.

When the regenerative motor M is used as a drive source and the electric motor 47 is used as a generator, the deflection angle of the swash plate of the sub pump SP is set to zero, and a substantially no-load state is achieved.

Next, the effect of the assist control will be described.

A high-pressure selection switching valve 71 is provided on the discharge passage 68 that guides the working oil discharged from the sub pump SP to the neutral flow passages 6 and 18, and the high-pressure selection switching valve 71 selects one of the high pressures in the passage 55 and the passage 56. The discharge oil is supplied to the sub pump SP. As a result, when the load on the actuator is high, a large amount of auxiliary flow is supplied to the neutral flow paths 6 and 18 on the high-pressure side, so that the operating speed of the hydraulic excavator can be ensured.

In addition, since the high-pressure selection switching valve 71 selects the high-pressure side of the passage 55 and the passage 56 , the hydraulic fluid discharged from the sub pump SP can be supplied to the high-pressure side. Furthermore, it is possible to prevent, for example, the generation of throttle pressure in the proportional electromagnetic throttle valve as in the conventional case where the discharge oil of the sub pump SP is proportionally distributed and supplied to the passage 55 and the passage 56 via the proportional electromagnetic throttle valve. Loss and auxiliary power are reduced, and energy consumption can be reduced. Furthermore, since the proportional electromagnetic throttle valve is not used, the auxiliary system for supplying the discharge oil from the sub pump SP to the neutral flow paths 6 and 18 can be made a low-cost and robust system.

In addition, since hydraulic oil can be supplied to the neutral passages 6 and 18 by the sub pump SP while performing the turning regeneration control and the boom regeneration control, for example, a so-called horizontal operation of moving the arm while contracting the boom cylinder BC is performed. In the case of pressing (or leveling (Japanese: ならし)) operation, the arm can be assisted by the regenerated power while being regenerated by the boom regeneration control. Therefore, the energy consumption of the whole system can be reduced.

The working oil in the passage 55 is supplied to one pilot chamber 71 a of the high pressure selection switching valve 71 through the damping orifice 74 , and the working oil in the passage 56 is supplied to the other pilot chamber 71 b through the damping orifice 75 . Thereby, the sliding core of the high-pressure selective switching valve 71 can be prevented from violently moving, the switching action between the neutral position, the first switching position, and the second switching position of the high-pressure selective switching valve 71 can be attenuated, and the shock generated during switching can be reduced. .

According to the above embodiment, the following effects can be obtained.

In the past, during the working process of the boom cylinder BC and the swing motor RM, it was possible to regenerate energy from the residual flow of the boom cylinder BC and swing motor RM through boom regeneration control and swing regeneration control. However, when operating the boom cylinder BC , In the case of an actuator other than the rotary motor RM, energy regeneration cannot be performed.

On the other hand, in this embodiment, for example, when the operating oil pressure in the neutral flow path 6 or the neutral flow path 18 reaches the set pressure while the bucket, the arm, etc. are being operated, the regeneration passage switching valve 57 or the The passage switching valve 58 is switched to the regenerative position and the working oil in the neutral flow path 6 or the neutral flow path 18 is guided to the regenerative motor M. Therefore, even when actuators other than the boom cylinder BC and the swing motor RM are operated, the hydraulic energy of the remaining hydraulic oil can be regenerated. Therefore, since it is possible to regenerate energy that has been discarded in the past, more energy can be regenerated while reducing energy loss, and energy consumption of the entire system can be reduced.

The embodiments of the present invention have been described above, but the above-mentioned embodiments merely show a part of application examples of the present invention, and are not intended to limit the scope of the present invention to the specific configurations of the above-mentioned embodiments.

Claims (8)

1. A control system (100) of a hybrid construction machine, wherein the control system of the hybrid construction machine comprises: A circuit system (S1, S2) having operation valves (1-5, 14-17) for supplying and discharging the working fluid supplied from the main pumps (MP1, MP2) through the main passages (6, 18) to the actuators ; a main overflow valve (8, 19), which is used to keep the working fluid pressure of the main passage (6, 18) below the main overflow pressure; a regeneration passage (55, 56) branching from a portion of the main passage (6, 18) between the main pump (MP1, MP2) and the operation valve (1-5, 14-17); a regeneration motor (M) for regeneration, which is rotated by the working fluid guided through the regeneration passage (55, 56); and regeneration passage switching valves (57, 58), which can open and close the regeneration passages (55, 56), when the pressure of the working fluid in the main passages (6, 18) reaches the ratio When the main relief pressure is lower than the set pressure, the regeneration passage switching valve (57, 58) is switched to an open position using the working fluid pressure as a pilot pressure. 2. The control system (100) of the hybrid construction machine according to claim 1, wherein the control system (100) of the hybrid construction machine further comprises: A main passage switching valve (63), which is provided in the main passage (6, 18) at a position downstream of the operation valve (1-5, 14-17), and enables the main passage (6 , 18) opening and closing; and A controller (C) that switches and controls the regeneration passage switching valve (57, 58) to an open position and switches and controls the main passage switching valve (63) to a closed position when the actuator is not in operation. 3. The control system (100) of the hybrid construction machine according to claim 2, wherein the control system (100) of the hybrid construction machine further comprises: a pilot pressure source (PP) for generating pilot pressure; and a solenoid valve (62) capable of supplying pilot pressure from the pilot pressure source (PP) to the pilot passage (60) according to an instruction signal from the controller (C), If the solenoid valve (62) supplies pilot pressure to the pilot passage (60), under the action of the pilot pressure, the regeneration passage switching valves (57, 58) switch to the open position and the main passage The switching valve (63) is switched to the closed position. 4. The control system (100) of a hybrid construction machine according to claim 3, wherein, The regeneration channel switching valve (57, 58) has: a first pilot chamber (57a, 58a), leading the working fluid pressure of the main passage (6, 18) to the first pilot chamber (57a, 58a); The second pilot chamber (57b, 58b) guides the pilot pressure from the pilot pressure source (PP) to the second pilot chamber (57b, 58b). 5. The control system (100) of a hybrid construction machine according to claim 2, wherein, The control system (100) of the hybrid construction machine also includes a throttling member (9, 20), which is connected to the operating valve ( 1 to 5, 14 to 17), for generating the pilot pressure delivered to the regulators (12, 23) that control the capacity of the main pumps (MP1, MP2), The main passage switching valve (63) is arranged between the operating valves (1-5, 14-17) and the throttling parts (9, 20), When the pilot pressure delivered by the switching control of the main passage switching valve (63) is at the closed position to be the minimum, the regulator (12, 23) controls the capacity of the main pump (MP1, MP2) to become the largest. 6. The control system (100) of a hybrid construction machine according to claim 2, wherein, When the regeneration passage switching valve (57, 58) is switched to the open position, the controller (C) controls the regeneration flow rate of the regeneration motor (M) so that the flow rate of the main passage (6, 18) The working fluid pressure is equal to or higher than the minimum working pressure of the actuator. 7. The control system (100) of a hybrid construction machine according to any one of claims 1 to 6, wherein, The loop system (S1, S2) is composed of two loop systems, and the control system (100) of the hybrid construction machine also includes: an auxiliary pump (SP) that supplies working fluid to the main passage (6, 18) via an auxiliary passage (68) by rotating in conjunction with the regenerative motor (M); and an auxiliary switching valve (71) provided in the auxiliary passage (68) for supplying the working fluid supplied from the auxiliary pump (SP) to at least one of the two circuit systems (S1, S2) or said main pathway (6, 18), The auxiliary switching valve (71) is switched so that the working fluid supplied from the auxiliary pump (SP) flows more into the main passages (6, 18) of the two circuit systems (S1, S2) The main passage (6, 18) in which the working fluid pressure is higher. 8. The control system (100) of a hybrid construction machine according to claim 7, wherein, The auxiliary switching valve (71) uses the working fluid pressure of the main passage (6, 18) of one of the two circuit systems (S1, S2) and the main passage (6, 18) of the other two circuit systems (S1, S2) 18) The working fluid pressure is used as the pilot pressure to switch, Both pilot pressures are guided to the auxiliary switching valve (71) via damping throttles (74, 75) that dampen the switching operation of the auxiliary switching valve (71).