JP2010261538A - Hybrid construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance power generation efficiency by increasing displacements per rotation of variable displacement type first and second main pumps MP1, MP2 in a state of discharging a standby flow rate even when the rotation speed of an engine E is low. <P>SOLUTION: A controller C supplies the discharge amounts of the first and second main pumps MP1, MP2 to a power generator G when operation valves 2-6, 14-17 are held at neutral positions and, if the rotation speed of the engine E is low at that time, lets low pilot pressures controlled by pressure reducing valves R1, R2 act on regulators 12, 23 which control the tilt angles of the first and second main pumps MP1, MP2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a construction machine that charges a battery with energy during standby.

The present applicant has already provided this type of construction machine as an application related to Japanese Patent Application No. 2008-143410.
FIG. 3 shows an invention related to the above Japanese Patent Application No. 2008-143410 (hereinafter referred to as “conventional construction machine”). In FIG. 3, a system for generating power using regenerative energy when the operation valve is kept in the neutral position, in other words, when the actuator connected to the operation valve is in a non-working state will be described.
In addition, since the structure of parts other than the system using the said regenerative energy is the same as embodiment of this invention, it demonstrates in detail in the column of description of embodiment.

The conventional construction machine shown in FIG. 3 relates to a power shovel, and is provided with variable capacity type first and second main pumps MP1 and MP2 driven by an engine E. MP2 rotates coaxially. In the figure, reference numeral 1 denotes a generator provided in the engine E, which exhibits the power generation function by utilizing the remaining power of the engine E.
The first main pump MP1 is connected to the first circuit system S1, and the second main pump MP2 is connected to the second circuit system S2.

  The first circuit system S1 includes, in order from the upstream side, an operation valve 2 that controls the swing motor RM, an operation valve 3 that controls an arm cylinder (not shown), and a second speed for the boom that controls the boom cylinder BC. An operation valve 4, an operation valve 5 that controls a preliminary attachment (not shown), and an operation valve 6 that controls a first traveling motor (not shown) for left running are connected.

Each of the operation valves 2 to 6 is connected to the first main pump MP <b> 1 via the neutral flow path 7 and the parallel path 8.
A throttle 9 for generating a pilot pressure is provided in the neutral flow path 7 on the downstream side of the first travel motor operating valve 6. The throttle 9 generates a high pilot pressure upstream if the flow rate therethrough is large, and generates a low pilot pressure if the flow rate is small.

  The second circuit system S2 includes an operation valve 14 for controlling a second traveling motor for right traveling (not shown), an operation valve 15 for controlling a bucket cylinder (not shown), in order from the upstream side. An operation valve 16 for controlling the boom cylinder BC and an operation valve 17 for arm 2 speed for controlling an arm cylinder (not shown) are connected. The operation valve 16 is provided with a sensor for detecting the operation direction and the operation amount, and the operation signal is transmitted to the controller C.

The operation valves 14 to 17 are connected to the second main pump MP2 through the neutral flow path 18, and the operation valve 15 and the operation valve 16 are connected to the second main pump MP2 through the parallel passage 19. .
In the neutral flow path 18, a throttle 20 is provided on the downstream side of the operation valve 17. The throttle 20 functions in the same manner as the throttle 9 of the first circuit system S 1.

  The neutral flow paths 7 and 18 in the first and second circuit systems S1 and S2 as described above have the first and second flow paths when the operation valves 2 to 6 and 14 to 17 are all in the neutral position or in the vicinity of the neutral position. All or part of the oil discharged from the main pumps MP1 and MP2 is guided to the tank T through the throttles 9 and 20, but at this time, the flow rate passing through the throttles 9 and 20 increases, so that it is high as described above. A pilot pressure is generated.

On the other hand, when the operation valves 2 to 6 and 14 to 17 are switched in a full stroke state, the neutral flow paths 7 and 18 are closed and the fluid does not flow. Therefore, in this case, the flow rate flowing through the throttles 9 and 20 almost disappears, and the pilot pressure is kept at zero.
However, depending on the operation amount of the operation valves 2 to 6 and 14 to 17, a part of the pump discharge amount is guided to the actuator and a part is guided to the tank T from the neutral flow paths 7 and 18. 9 and 20 generate a pilot pressure corresponding to the flow rate flowing through the neutral flow paths 7 and 18. In other words, the throttles 9 and 20 generate pilot pressures corresponding to the operation amounts of the operation valves 2 to 6 and 14 to 17.

In the neutral flow paths 7 and 18 as described above, the pilot pressure electromagnetic switching valves 10 and 21 are provided between the most downstream operation valves 6 and 17 and the throttles 9 and 20. The pilot pressure switching valves 10 and 21 have their solenoids connected to the controller C.
The pilot pressure switching solenoid valves 10 and 21 as described above maintain the fully open position shown in the figure by the action of the spring force of the spring when the solenoid is not excited, and resist the spring force of the spring when the solenoid is excited. To switch to the closed position.

In addition, although the neutral flow paths 7 and 18 are connected between the operation valves 6 and 17 and the pilot pressure switching electromagnetic valves 10 and 21, pilot flow paths 11 and 22 are connected. , 22 are connected to regulators 12, 23 that control the tilt angles of the first and second main pumps MP1, MP2.
The regulators 12 and 23 control the tilt angles of the first and second main pumps MP1 and MP2 in inverse proportion to the pilot pressure in the pilot flow paths 11 and 22, and control the displacement volume per one rotation. Accordingly, when the operation valves 2 to 6 and 14 to 17 are fully stroked and the flow of the neutral flow paths 7 and 18 disappears and the pilot pressure becomes zero, the tilt angles of the first and second main pumps MP1 and MP2 are increased. And the displacement volume per revolution is maximized.

On / off valves 58 and 59 having solenoids are connected to the first and second main pumps MP1 and MP2 as described above via flow paths 55 and 56, respectively. The flow paths 55 and 56 are connected to the first and second main pumps MP1 and MP2 on the upstream side of the first and second circuit systems S1 and S2.
The on-off valves 58 and 59 maintain the illustrated closed position when the solenoid is in a non-excited state, maintain the open position when the solenoid is excited, and connect the solenoids to the controller C.

  Further, these on-off valves 58 and 59 are connected to the hydraulic motor M through the junction passage 57, the check valve 60 and the connection passage 46. The hydraulic motor M rotates in conjunction with the generator G, and the electric power generated by the generator G is charged to the battery 26 via the inverter I.

Next, a case where power is generated using regenerative energy with the above-described conventional apparatus will be described.
As described above, when the operation valves 2 to 6 and 14 to 17 are held in the neutral positions and the actuators connected thereto are brought into a non-working state, the pressure in the most downstream portion of the neutral flow paths 7 and 18 becomes maximum. . When the first and second pressure sensors 13 and 24 detect the pressure at this time, the pressure signal is input to the controller C.

The controller C that receives the signals from the first and second pressure sensors 13 and 24 switches the pilot pressure switching electromagnetic valves 10 and 21 to the closed position and switches the on-off valves 58 and 59 to the open position.
When the pilot pressure switching solenoid valves 10 and 21 are switched to the closed position as described above, the pressures in the neutral flow paths 7 and 18 are applied to the regulators 12 and 23 via the pilot flow paths 11 and 22, respectively. (2) The tilt angle of the main pumps MP1 and MP2 is minimized, and the displacement volume per rotation of the first and second main pumps MP1 and MP2 is minimized. In other words, the first and second main pumps MP1 and MP2 discharge the standby flow rate.

  At this time, since the on-off valves 58 and 59 are switched to the open position as described above, the standby flow rate passes through the flow paths 55 and 56 and the on-off valves 58 and 59 and merges in the merge passage 57. Since the standby flow rate merged in the merging passage 57 is guided to the hydraulic motor M through the check valve 60 and the connection passage 46, the hydraulic motor M rotates and the generator G also rotates. The electric power generated by the generator G is charged into the battery 26 via the inverter I.

  When the operation valves 2 to 6 and 14 to 17 are switched to the switching position from the above state, the pressures of the neutral flow paths 7 and 18 are lowered accordingly, but the pressures of the pilot flow paths 11 and 22 and the regulators 12 and 23 are It gradually decreases due to oil leaks. When the pressures detected by the first and second pressure sensors 13, 24 become lower than the set pressure, the controller C returns the pilot pressure switching electromagnetic valves 10, 21 to the open position and closes the on-off valves 58, 59 to the closed position. Return to.

  As described above, if the pilot pressure switching electromagnetic valves 10 and 21 are kept in the open position and the on-off valves 58 and 59 are kept in the closed position, the discharge amounts of the first and second main pumps MP1 and MP2 are supplied to a predetermined actuator. In addition, the regulators 12 and 23 control the tilt angles of the first and second main pumps MP1 and MP2 so as to ensure a discharge flow rate proportional to the operation amount of the operation valve.

Japanese Patent Application No. 2008-143410

  In the conventional apparatus as described above, the tilt angle of the pump is minimized when generating power using regenerative energy, and the displacement volume per one rotation is reduced. For this reason, there is a problem that the energy for charging the battery becomes insufficient, and when the pump is used in a state where the displacement volume is reduced, the pump efficiency is deteriorated and the energy loss is increased accordingly.

  Further, if a large hydraulic energy is to be obtained in a state where the displacement of the pump is reduced, the rotational speed of the pump must be increased. However, in order to increase the number of revolutions of the pump, it is necessary to increase the number of revolutions of the engine that is the prime mover. However, if the number of revolutions of the engine is increased, the amount of energy consumption increases and the cause of noise also increases. There was a problem of becoming.

Further, the pilot pressure switching electromagnetic valves 10 and 21 and the on-off valves 58 and 59 are individually controlled by the controller C, and there is no interlocking between them. Therefore, for example, if an abnormality occurs in the pilot pressure switching electromagnetic valve 10 and it does not switch to the closed position, the first main pump MP1 has a large displacement volume per one rotation, and the second main pump MP2 As a result, the discharge pressure is higher in the first main pump MP1.

If the first and second main pumps MP1 and MP2 rotate in the above-described state, a difference in the discharge pressure can be made. Therefore, the flow on the high discharge pressure side flows into the low discharge pressure side via the merge passage 57, and the hydraulic motor There arises a problem that no fluid is supplied to M.
An object of the present invention is to provide a hybrid construction machine in which an electromagnetic switching control valve and an electromagnetic valve are hydraulically linked and regenerative energy can be used efficiently.

  The present invention provides a circuit system that is connected to a variable displacement pump and that is provided with a plurality of operation valves, and discharge oil of the variable displacement pump when all of the operation valves provided in the circuit system maintain a neutral position. Between the neutral flow path leading to the tank, the pilot pressure generating throttle provided in the neutral flow path further downstream of the operation valve located on the most downstream side, and between the most downstream operating valve and the pilot pressure generating throttle It is based on a control device for a construction machine that includes a pilot flow path that guides the generated pressure and a regulator that is connected to the pilot flow path and controls the tilt angle of the variable displacement pump.

  According to a first aspect of the present invention, there is provided a pilot pressure switching valve provided in a neutral flow path between the most downstream operation valve and a throttle for generating a pilot pressure and capable of switching between a fully open position and a closed or throttle position, A pressure reducing valve provided in the flow path, a pilot flow path switching valve for opening and closing a bypass flow path bypassing the pressure reducing valve, a hydraulic motor connected in parallel to the variable displacement pump with respect to the circuit system, and the variable An on-off valve that opens and closes a flow path connecting the displacement pump and the hydraulic motor, and a pilot control that connects or shuts off the communication of the pilot chamber of the pilot pressure switching valve and the open / close valve to the neutral flow path A valve and a generator linked to the hydraulic motor are provided.

  According to a second aspect of the present invention, there is provided a pilot pressure switching valve provided in a neutral flow path between the most downstream operating valve and a throttle for generating pilot pressure, and capable of switching between a fully open position and a closed or throttle position, and a pilot pressure source A pilot flow path switching valve provided in the pilot flow path and switchable between a position connecting the neutral flow path and the regulator and a position connecting the pilot pressure source and the regulator, and the pilot A pressure reducing valve provided between the pressure source and the pilot flow path switching valve, a hydraulic motor connected in parallel to the variable displacement pump with respect to the circuit system, and the variable displacement pump and the hydraulic motor are connected. The on-off valve that opens and closes the flow path, and the pilot pressure switching valve and the pilot chamber of the on-off valve are communicated with or shut off from the pilot pressure source. A pilot control valve or, and a generator which is linked to the hydraulic motor.

  In a third aspect of the invention, the pilot pressure switching valve can be switched between a throttle position and a fully open position.

According to the first to third inventions, when using regenerative energy, the pilot pressure reduced by the pressure reducing valve acts on the regulator. The pilot pressure reduced by the pressure reducing valve is relatively lower than the pilot pressure introduced when the operation valve is in the neutral position.
If a relatively low pilot pressure acts on the regulator as described above, the tilt angle of the variable displacement pump will be kept larger than the minimum angle, and the displacement volume per rotation of the pump will be It becomes larger than when the tilt angle is minimum.

Therefore, sufficient energy for charging the battery can be secured, and the pump can be used with the displacement volume increased as described above, so that the pump efficiency is improved and the energy efficiency is improved overall. Will do.
Further, since the displacement volume of the pump per rotation can be increased, sufficient energy for charging the battery can be secured without increasing the rotation speed of the pump. Therefore, it is not necessary to increase the number of revolutions of the engine that is the prime mover, and accordingly, energy consumption is reduced and noise caused by engine noise can be reduced.

In addition, since the pilot chamber of the pilot pressure switching valve and the on-off valve communicates with the neutral flow path or the pilot pressure source via the pilot control valve, the pilot pressure switching valve and the on-off valve are hydraulically linked. . Therefore, if the pilot control valve is operated, the pilot pressure switching valve and the on-off valve can be synchronized, and safety is improved.
Further, according to the third invention, the pilot pressure switching valve maintains the throttle position when each operation valve is maintained at the neutral position. Therefore, even when the operation valve is switched from the neutral position, the responsiveness is maintained. Get better.

It is a circuit diagram of a 1st embodiment. It is a circuit diagram of a 2nd embodiment. It is a conventional circuit diagram.

FIG. 1 shows a first embodiment. In this first embodiment, an engine E having a generator 1, variable displacement first and second main pumps MP1 and MP2, first and second circuit systems S1 and S2 are shown. Since the configurations of the regulators 12 and 23 and the first and second pressure sensors 13 and 24 are the same as those in the prior art, detailed description thereof will be omitted, and the same components will be described with the same reference numerals.
The engine E is provided with a rotation speed sensor (not shown).

Pilot pressure switching valves PV1 and PV2 are provided in the neutral flow paths 7 and 18 between the most downstream operating valves 6 and 17 and the throttles 9 and 20. These pilot pressure switching valves PV1 PV2 is provided with a pilot chamber on one side and the spring force of the spring on the other.
When the pressure is not acting on the pilot chamber, the pilot pressure switching valves PV1 and PV2 configured as described above maintain the fully opened position shown in the figure by the action of the spring force of the spring. When the pilot pressure is applied to the pilot chamber, the throttle chamber is switched to the throttle position against the spring force of the spring. The throttle opening when the pilot pressure switching valves PV1 and PV2 are switched to the throttle position is set to be smaller than the openings of the throttles 9 and 20.

The pilot passages 11 and 22 are provided with pressure reducing valves R1 and R2 and pilot passage switching valves PL1 and PL2 in parallel. That is, the pilot flow path switching valves PL1 and PL2 are provided in a bypass flow path that bypasses the pressure reducing valves R1 and R2.
The pilot flow path switching valves PL1 and PL2 configured as described above maintain the open position when the solenoid provided on one of them is de-energized, and in the process from the neutral flow paths 7 and 18 to the pilot flow paths 11 and 22, The pressure reducing valves R1 and R2 are bypassed. The pilot flow path switching valves PL1 and PL2 maintain a closed position when the solenoid is excited, and allow the neutral flow paths 7 and 18 to communicate with the pilot flow paths 11 and 22 only through the pressure reducing valves R1 and R2.

  When all of the operation valves 2 to 6 and 14 to 17 are in the neutral position and the pilot pressure switching valves PV1 and PV2 are in the fully open position, the neutral flow paths 7 and 18 bypass the pressure reducing valves R1 and R2. And the pilot channels 11 and 22 communicate with each other, the pressure upstream of the throttles 9 and 20 directly acts on the regulators 12 and 23 as the pilot pressure. As described above, when the pressures upstream of the throttles 9 and 20 directly act on the regulators 12 and 23 when all of the operation valves 2 to 6 and 14 to 17 are in the neutral positions, the first and second main pumps MP1 and MP2 Maintains the minimum tilt angle, minimizes the displacement volume per revolution and ensures a standby flow rate.

On the other hand, if the pilot flow path switching valves PL1 and PL2 are switched to the closed position and the neutral flow paths 7 and 18 and the pilot flow paths 11 and 22 communicate with each other via the pressure reducing valves R1 and R2, the regulators 12 and 23 are connected. The pilot pressure introduced is the pressure reduced by the pressure reducing valves R1 and R2. In other words, the pilot pressure acting on the regulators 12 and 23 is lower by the amount reduced by the pressure reducing valves R1 and R2 than when the pilot flow path switching valves PL1 and PL2 are in the open position.
Therefore, the tilt angles of the first and second main pumps MP1, MP2 are larger than when all the operation valves 2-6, 14-17 are in the neutral position and the pilot flow path switching valves PL1, PL2 are in the open position. The displacement volume per rotation becomes relatively large.

  Furthermore, the first and second pressure sensors 13 and 24 are connected to the pilot flow paths 11 and 22, and the pressure signals detected by the first and second pressure sensors 13 and 24 are transmitted to the controller C. . And since the pilot pressure of pilot flow paths 11 and 22 changes according to the amount of operation of operation valves 2-6, 14-17, the pressure signal which the 1st and 2nd pressure sensors 13 and 24 detect is the 1st. , And changes in accordance with the required flow rate of the two circuit systems S1 and S2.

  Further, the controller C can detect whether or not the operation valves 2 to 6 and 14 to 17 are all in the neutral position according to the pressure signals detected by the first and second pressure sensors 13 and 24. That is, the controller C stores in advance the pressure generated upstream of the throttles 9 and 20 when the operation valves 2 to 6 and 14 to 17 are all in the neutral position as the set pressure. Therefore, when the pressure signals of the first and second pressure sensors 13 and 24 reach the set pressure, the controller C indicates that all the operation valves are in the neutral position and the actuator connected to the operation valve is in a non-working state. Judgment can be made.

  The first and second pressure sensors 13 and 24 that detect the set pressure can function as operation status detection means that detects the operation status of the operation valves 2 to 6 and 14 to 17. However, the operation status detection means is not limited to the pressure sensor. For example, if a sensor for detecting a neutral position is provided in each of the operation valves 2 to 6 and 14 to 17 and this sensor is connected to the controller C, the sensor for detecting the neutral position becomes the operation status detection means.

On / off valves 58 and 59 are connected to the first and second main pumps MP1 and MP2 as described above via flow paths 55 and 56, respectively. The flow paths 55 and 56 are connected to the first and second main pumps MP1 and MP2 on the upstream side of the first and second circuit systems S1 and S2.
The on-off valves 58 and 59 are provided with a pilot chamber on one side and a spring force of the spring on the other side. When the pilot pressure is not applied to the pilot chamber, the illustrated closed position is maintained by the action of the spring force of the spring, and when the pilot pressure is applied, the open position is maintained by switching against the spring force of the spring.

The pilot chambers of the pilot pressure switching valves PV1 and PV2 and the pilot chambers of the on-off valves 58 and 59 are communicated with each other through a passage.
Further, the pilot chambers of the pilot pressure switching valves PV1 and PV2 and the pilot chambers of the on-off valves 58 and 59 are connected to the pilot control valves PC1 and PC2, respectively. Is provided with a solenoid connected to the controller C, and the spring force of the spring is applied to the other.

The pilot control valves PC1 and PC2 configured as described above maintain the illustrated closed position by the action of the spring when the solenoid is de-energized, and maintain the open position when the solenoid is energized. The pilot chambers of the pilot pressure switching valves PV1 and PV2 and the pilot chambers of the on-off valves 58 and 59 are respectively communicated with the neutral flow paths 7 and 18 on the upstream side of the pilot pressure switching valves PV1 and PV2.
Therefore, when the pilot control valves PC1 and PC2 are in the open position, the pilot pressure switching valves PV1 and PV2 and the open / close valves 58 and 59 are switched in conjunction with the pressures of the neutral flow paths 7 and 18, respectively.

Further, the on-off valves 58 and 59 are connected to the hydraulic motor M through the junction passage 57 and the check valve 60. The hydraulic motor M rotates in conjunction with the generator G, and the electric power generated by the generator G is charged to the battery 26 via the inverter I.
The hydraulic motor M and the generator G may be directly connected to each other or may be linked via a reduction gear (not shown).

  In the first embodiment as described above, when one of the first and second circuit systems S1 and S2 is switched and the actuator connected to the operation valve is operated, the operation amount of the operation valve is changed. Thus, the flow rate flowing through the neutral flow paths 7 and 18 changes. The pilot pressure generated on the upstream side of the pilot pressure generating throttles 9 and 20 changes in accordance with the flow rate flowing in the neutral flow paths 7 and 18, and the regulators 12 and 23 are controlled in accordance with the pilot pressure. 2 The tilt angle of the main pumps MP1 and MP2 is controlled. That is, as the pilot pressure decreases, the tilt angle is increased to increase the displacement volume per rotation of the first and second main pumps MP1, MP2. On the contrary, as the pilot pressure increases, the tilt angle is decreased to decrease the displacement volume per rotation of the first and second main pumps MP1 and MP2.

Next, a case where the operator inputs a standby regeneration command signal to the controller C by manual operation in order to rotate the hydraulic motor M and charge the battery 26 will be described.
When the standby regeneration command signal is not input from the operator, the controller C holds the pilot flow path switching valves PL1 and PL2 and the pilot control valves PC1 and PC2 in the illustrated normal positions. Accordingly, in this state, the tilt angles of the first and second main pumps MP1 and MP2 are controlled by the pressure upstream of the pilot pressure generating throttles 9 and 20.

  Accordingly, in the above state, for example, if all of the operation valves 2 to 6 and 14 to 17 are kept in the neutral position, the pilot pressure guided to the pilot flow paths 11 and 22 becomes maximum. When the pilot pressure is maximized, the regulators 12 and 23 reduce the tilt angle of the first and second main pumps MP1 and MP2 to minimize the displacement volume per rotation. , MP2 ensures a standby flow rate.

  On the other hand, when the standby regeneration command signal is input to the controller C by the manual operation of the operator, the controller C determines whether or not the pressure signals detected by the first and second pressure sensors 13 and 24 have reached the set pressure. . If the pressure signal does not reach the set pressure, it is determined that the actuator connected to one of the operation valves of the first and second circuit systems S1 and S2 is working, and the pilot flow path switching valve PL1, PL2 and pilot control valves PC1, PC2 are held in the closed position.

  If the pressure signal detected by the first and second pressure sensors 13 and 24 has reached the set pressure, the controller C is in a non-working state of the actuator connected to any of the operation valves of the first and second circuit systems S1 and S2. The solenoids of the pilot control valves PC1 and PC2 are excited.

  If the solenoids of the pilot control valves PC1 and PC2 are excited as described above, the pilot control valves PC1 and PC2 are switched to the open position. The pressure of the flow paths 7 and 18 acts. Accordingly, the pilot pressure switching valves PV1 and PV2 are switched to the throttle position, and the on-off valves 58 and 59 are switched to the open position. That is, the pilot pressure switching valves PV1 and PV2 and the on-off valves 58 and 59 are switched in conjunction with each other hydraulically.

  In a state where the pilot pressure switching valves PV1 and PV2 and the on-off valves 58 and 59 are switched as described above, the controller C rotates based on the signal from the rotation speed sensor that detects the rotation speed of the engine E. Whether the number is high or low is determined. The criterion for determining the rotational speed is stored in the controller C in advance.

  When engine E has a high rotational speed, controller C puts the pilot flow path switching valves PL1, PL2 in a non-excited state to keep the pilot flow path switching valves PL1, PL2 in the open position. Thus, if pilot flow path switching valves PL1 and PL2 are kept in the open position, the pilot pressure in neutral flow paths 7 and 18 is regulated via pilot flow path switching valves PL1 and PL2 and pilot flow paths 11 and 22. 12 and 23. Therefore, the first and second main pumps MP1 and MP2 maintain the tilt angle for securing the standby flow rate.

  When the rotational speed of the engine E is high as described above, the tilt angle for maintaining the standby flow rate in the first and second main pumps MP1, MP2 by keeping the pilot flow path switching valves PL1, PL2 in the open position. This is because if the rotation speed of the engine E is high, the first and second main pumps MP1 and MP2 can secure a predetermined discharge amount at the rotation speed even if the displacement volume per rotation is small. is there.

On the other hand, when the rotational speed of engine E is low, controller C excites the solenoids of pilot flow path switching valves PL1, PL2 to switch pilot flow path switching valves PL1, PL2 to the closed position. If the pilot flow path switching valves PL1, PL2 are switched to the closed position, the pilot pressure in the neutral flow paths 7, 18 is reduced by the pressure reducing valves R1, R2 and acts on the regulators 12, 23. If the pilot pressures reduced by the pressure reducing valves R1 and R2 are applied to the regulators 12 and 23, the tilt angles of the first and second main pumps MP1 and MP2 become larger than when the standby flow rate is ensured, and per revolution. The displacement volume of increases.
Therefore, even if the rotation speed of the engine E is low, the first and second main pumps MP1 and MP2 can ensure a predetermined discharge amount.

  In any case, since the discharge amounts of the first and second main pumps MP1 and MP2 are supplied to the hydraulic motor M via the on-off valves 58 and 59, the generator G is rotated by the driving force of the hydraulic motor M. To generate electricity. The electric power generated by the generator G is charged to the battery via the inverter I.

Even if the hydraulic motor M is rotated and the generator G is generating power as described above, if the actuator is operated by operating the operation valve, the controller C switches the pilot flow path. The solenoids of the valves PL1 and PL2 and the pilot control valves PC1 and PC2 are brought into a non-excited state. Therefore, the regulators 12 and 23 match the tilt angles of the first and second main pumps MP1 and MP2 with the required flow rate according to the operation amount of the operation valve.
At this time, even if there is a slight switching delay in the pilot pressure switching valves PV1 and PV2, the pilot pressure switching valves PV1 and PV2 maintain the throttle position. It will come out quickly through the aperture.

Heretofore, the case where the solenoids of the pilot control valves PC1 and PC2 are normally de-energized has been described. However, the pilot control valves PC1 and PC2 may be normally excited to keep the open state. In this case, when the operation valves 2 to 6 and 14 to 17 are switched to the neutral position and the pressure in the neutral flow paths 7 and 18 becomes equal to or higher than the set pressure, the pilot pressure switching valves PV1 and PV2 and the on-off valves 58, 59 automatically switches from the normal position.
Whether the solenoids of the pilot control valves PC1 and PC2 are normally de-energized or energized may be selected as necessary.

  In the second embodiment shown in FIG. 2, a pilot pump PP as a pilot hydraulic pressure source is specially provided, and pressure reducing valves R1, R2 and pilot flow path switching valves PL1, PL2 are connected in series to the pilot pump PP. . Further, pilot control valves PC1 and PC2 are connected to the pilot pump PP in parallel with the pressure reducing valves R1 and R2. The pilot control valves PC1 and PC2 are connected to the pressures of the neutral flow paths 7 and 18, respectively. Is switched as pilot pressure.

The pilot flow path switching valves PL1 and PL2 can be switched between the first position and the second position, hold the first position in the normal state where the solenoid is in a non-excited state, and the second position when the solenoid is excited. To switch to.
And in the said 1st position, while making the neutral flow paths 7 and 18 and the pilot flow paths 11 and 22 communicate, the communication with the pilot pump PP and the pilot flow paths 11 and 22 is interrupted | blocked. In the second position, the pilot pump PP and the pilot flow paths 11 and 22 are communicated with each other, and the neutral flow paths 7 and 18 and the pilot flow paths 11 and 22 are disconnected from each other.

  Further, pressure reducing valves R1, R2 are connected between the pilot pump PP and the pilot flow path switching valves PL1, PL2. The reason why the pressure reducing valves R1 and R2 are provided between the pilot pump PP and the pilot flow path switching valves PL1 and PL2 is to stabilize the pilot pressure supplied from the pilot pump PP. The pilot pressure reduced by the pressure reducing valves R1 and R2 is made lower than the pilot pressure required when the first and second main pumps MP1 and MP2 secure the standby flow rate, as in the first embodiment. ing.

  On the other hand, the pilot control valves PC1 and PC2 connect the pilot chamber provided on one side to the neutral flow paths 7 and 18 on the upstream side of the pilot pressure switching valves PV1 and PV2, and on the opposite side to the pilot chamber. A spring is provided. When the pilot pressure is not applied to the pilot control valves PC1 and PC2, the illustrated closed position is maintained. However, when the pilot pressure is applied, the pilot control valve PC1 is switched to the open position, and pressure oil from the pilot pump PP is supplied to the pilot pressure switching valve. Lead to the pilot room of PV1 and PV2.

  The pilot chambers of the pilot pressure switching valves PV1 and PV2 and the pilot chambers of the on-off valves 58 and 59 are communicated with each other through a passage as in the first embodiment. Therefore, if the pilot pump PP pressure is led to the pilot pressure switching valves PV1 and PV2 via the pilot control valves PC1 and PC2, the pilot pump PP pressure is also led to the pilot chambers of the on-off valves 58 and 59. Become. That is, the pilot pressure switching valves PV1 and PV2 and the on-off valves 58 and 59 are hydraulically linked.

In the second embodiment configured as described above, when the operation valves 2 to 6 and 14 to 17 are in the neutral position and the pressure in the neutral flow paths 7 and 18 rises, the pilot control valves PC1 and PC2 are opened by the pressure. The pressure oil of the pilot pump PP is guided to the pilot chambers of the pilot pressure switching valves PV1 and PV2 and the on-off valves 58 and 59.
Therefore, the pilot pressure switching valves PV1 and PV2 are switched to the throttle position, and the on-off valves 58 and 59 are switched to the open position.

In the above state, the controller C detects the rotational speed of the engine E. If the rotational speed is high, the controller C maintains the pilot flow path switching valves PL1 and PL2 in the illustrated first position, and the pressure in the neutral flow paths 7 and 18 is increased. To the regulators 12 and 23. If the rotational speed of engine E is low, controller C excites the solenoids of pilot flow path switching valves PL1, PL2 to switch pilot flow path switching valves PL1, PL2 to the second position. When the pilot flow path switching valves PL1, PL2 are switched to the second position, the pressure of the pilot pump PP is reduced by the pressure reducing valves R1, R2 and guided to the regulators 12, 23.
Other functions and effects are the same as those of the first embodiment.

  In the above description, it is assumed that all the operation valves 2 to 6 and 14 to 17 of the first and second circuit systems S1 and S2 are maintained in the neutral position. The hydraulic motor M can be rotated also when any one of the operation valves 2 to 6 or 14 to 17 of the systems S1 and S2 is in the neutral position. In this case, one of the on-off valves 58 or 59 is switched to the open position, and the other on-off valve 58 or 59 is kept in the closed position. Accordingly, the oil discharged from one of the first and second main pumps MP1 and MP2 is supplied to the hydraulic motor M, and the generator G can be rotated by the rotational force of the hydraulic motor M.

The generator 1 provided in the engine E is connected to the battery charger 25, and the electric power generated by the generator 1 is charged to the battery 26 via the battery charger 25.
The battery charger 25 can charge the battery 26 even when connected to a normal household power supply 27. In other words, the battery charger 25 can be connected to an independent power source different from the device.

The first and second embodiments are characterized by increasing the tilt angle of the first and second main pumps MP1 and MP2 when the rotational speed of the engine E is low in a non-working state, and pushing it per one rotation. It is designed to increase the removal volume and to charge the electric power efficiently even when the engine E has a low rotational speed.
However, each of FIGS. 1 and 2 shown as the embodiment also discloses a system that diversifies the charge of power and uses the charged power. Therefore, this system will be described below.

  The actuator port of the swing motor operating valve 2 connected to the first circuit system S1 is connected to passages 28 and 29 communicating with the swing motor RM, and both of the passages 28 and 29 have brake valves 30 and 29, respectively. 31 is connected. When the operation valve 2 for the swing motor is maintained at the neutral position, the actuator port is closed and the swing motor RM maintains the stopped state.

When the operation valve 2 for the swing motor is switched in any one direction from the above state, one passage 28 is connected to the first main pump MP1, and the other passage 29 communicates with the tank. Accordingly, pressure oil is supplied from the passage 28 to rotate the turning motor RM, and return oil from the turning motor RM is returned to the tank through the passage 29.
When the operation valve 2 for the swing motor is switched in the opposite direction, the pump discharge oil is supplied to the passage 29, the passage 28 communicates with the tank, and the swing motor RM is reversed.

  When the swing motor RM is driven as described above, the brake valve 30 or 31 performs the function of a relief valve, and when the passages 28 and 29 exceed the set pressure, the brake valves 30 and 31 are opened. Thus, the pressure in the passages 28 and 29 is kept at the set pressure. In addition, if the swing motor operating valve 2 is returned to the neutral position while the swing motor RM is rotating, the actuator port of the control valve 2 is closed. Even if the actuator port of the operation valve 2 is closed in this way, the swing motor RM continues to rotate with its inertia energy, but the swing motor RM performs a pumping action when the swing motor RM rotates with the inertia energy. At this time, the passages 28 and 29, the turning motor RM, and the brake valve 30 or 31 form a closed circuit, and the inertia energy is converted into heat energy by the brake valve 30 or 31.

On the other hand, when the operation valve 16 is switched from the neutral position to one direction, the pressure oil from the second main pump MP2 is supplied to the piston side chamber 33 of the boom cylinder BC via the passage 32, and the rod side chamber 34 thereof. Is returned to the tank via the passage 35, and the boom cylinder BC extends.
When the operation valve 16 is switched in the opposite direction, the pressure oil from the second main pump MP2 is supplied to the rod side chamber 34 of the boom cylinder BC via the passage 35 and returned from the piston side chamber 33. The oil is returned to the tank via the passage 32, and the boom cylinder BC contracts. The operation valve 3 for the second speed boom is switched in conjunction with the operation valve 16.
A proportional electromagnetic valve 36 whose opening degree is controlled by the controller C is provided in the passage 32 connecting the piston side chamber 33 of the boom cylinder BC and the operation valve 16 as described above. The proportional solenoid valve 36 is kept in the fully open position in its normal state.

Next, the variable displacement sub pump SP that assists the outputs of the first and second main pumps MP1 and MP2 will be described.
The variable displacement sub-pump SP rotates with a driving force when the generator G is used as an electric motor. The variable displacement hydraulic motor M is also coaxially driven by the driving force of the electric motor G (generator G). It is configured to rotate. The electric motor G is connected to an inverter I connected to the battery 26, and the inverter I is connected to a controller C so that the controller C can control the rotation speed of the electric motor G and the like.
Further, the tilt angles of the sub pump SP and the hydraulic motor M as described above are controlled by tilt controllers 37 and 38, which are controlled by the output signal of the controller C.

A discharge passage 39 is connected to the sub pump SP. The discharge passage 39 joins the first assist passage 40 that joins the discharge side of the first main pump MP1 and the discharge side of the second main pump MP2. The first and second assist flow passages 41 and 41 have first and second electromagnetic proportional throttle valves 42 whose opening degree is controlled by the output signal of the controller C. , 43 are provided.
In the figure, reference numerals 44 and 45 are check valves provided in the first and second assist flow paths 40 and 41, and permit only the flow from the sub pump SP to the first and second main pumps MP1 and MP2.

  On the other hand, a connection passage 46 is connected to the hydraulic motor M. This connection passage 46 is connected to passages 28 and 29 connected to the turning motor RM via an introduction passage 47 and check valves 48 and 49. is doing. In addition, an electromagnetic switching valve 50 that is controlled to be opened and closed by the controller C is provided in the introduction passage 47, and between the electromagnetic switching valve 50 and the check valves 48 and 49, the pressure at the time of turning of the turning motor RM or the time of braking A pressure sensor 51 for detecting the pressure of the pressure sensor 51 is provided, and a pressure signal of the pressure sensor 51 is input to the controller C.

A safety valve 52 is provided at a position downstream of the electromagnetic switching valve 50 with respect to the flow from the turning motor RM to the connection passage 46 in the introduction passage 47. In the case where a failure occurs in the passage 46 system, such as the electromagnetic switching valve 50, the pressure of the passages 28 and 29 is maintained to prevent the turning motor RM from going away.
Further, an introduction passage 53 communicating with the connection passage 46 is provided between the boom cylinder BC and the proportional solenoid valve 36, and an electromagnetic opening / closing valve 54 controlled by the controller C is provided in the introduction passage 53. ing.

  Next, the case where the assist force of the sub-pump SP is used will be described. In this case, the assist flow rate of the sub-pump SP is set in advance, in which the controller C determines the tilt angle, hydraulic pressure of the sub-pump SP. Each control is performed by determining how to control the tilt angle of the motor M, the number of rotations of the electric motor G, and the like to be most efficient.

  If the pilot pressure switching valves PV1 and PV2 maintain the throttle position when the operation valve of either the first circuit system S1 or the second circuit system S2 is switched, the controller C can control these pilot pressure switching valves PV1. , PV2 is switched to the open position. If the pilot pressure switching valves PV1 and PV2 are kept in the open position, the pilot pressure in the pilot flow paths 11 and 22 is lowered, so that the lowered pilot pressure signal is passed through the first and second pressure sensors 13 and 24. The controller C switches the first and second on-off valves 58 and 59 to the closed positions shown in the figure. Therefore, the first and second main pumps MP1 and MP2 increase the displacement volume per one rotation with the lowered pilot pressure, and the total discharge amount of the first and second main pumps MP1 and MP2 1 and 2 are supplied to the actuators connected to the circuit systems S1 and S2.

Further, when increasing the displacement volume per rotation of the first main pump MP1 or the second main pump MP2 as described above, the controller C keeps the electric motor G always rotated. The drive source of the electric motor G is the electric power stored in the battery 26. However, as described above, a part of this electric power is stored using the discharge amounts of the first and second main pumps MP1 and MP2. , Energy efficiency will be very good.
When the sub pump SP rotates with the driving force of the electric motor G, the assist flow rate is discharged from the sub pump SP. The controller C controls the first and second pressure sensors 13 and 24 according to the pressure signals from the first and second pressure sensors 13 and 24, respectively. The opening amounts of the two proportional electromagnetic throttle valves 42 and 43 are controlled, and the discharge amount of the sub-pump SP is apportioned and supplied to the first and second circuit systems S1 and S2.

On the other hand, in order to drive the turning motor RM connected to the first circuit system S1, for example, when the turning valve 2 for the turning motor is switched in one direction, one passage 28 communicates with the first main pump MP1, The other passage 29 communicates with the tank to rotate the turning motor RM. At this time, the turning pressure is maintained at the set pressure of the brake valve 30. If the operation valve 2 is switched in the opposite direction, the other passage 29 communicates with the first main pump MP1 and the one passage 28 communicates with the tank to rotate the turning motor RM. However, the turning pressure at this time is also maintained at the set pressure of the brake valve 31.
Further, when the swing motor operating valve 2 is switched to the neutral position while the swing motor RM is turning, a closed circuit is formed between the passages 28 and 29 as described above, and the brake valve 30 or 31 is also formed. Maintains the closed circuit brake pressure and converts inertial energy into thermal energy.

If the pressure in the passage 28 or 29 is not maintained at a pressure required for the turning operation or the braking operation, the turning motor RM cannot be turned or braked.
Therefore, in order to keep the pressure in the passage 28 or 29 at the turning pressure or the brake pressure, the controller C controls the load of the turning motor RM while controlling the tilt angle of the hydraulic motor M. . That is, the controller C controls the tilt angle of the hydraulic motor M so that the pressure detected by the pressure sensor 51 is substantially equal to the swing pressure or brake pressure of the swing motor RM.

If the hydraulic motor M obtains a rotational force as described above, the rotational force acts on the electric motor G that rotates coaxially. The rotational force of the hydraulic motor M acts as an assist force on the electric motor G. . Therefore, the power consumption of the electric motor G can be reduced by the amount of the rotational force of the hydraulic motor M.
Further, the rotational force of the sub pump SP can be assisted by the rotational force of the hydraulic motor M, but at this time, the hydraulic motor M and the sub pump SP combine to exhibit a pressure conversion function.

That is, the pressure flowing into the connection passage 46 is often lower than the pump discharge pressure. In order to maintain a high discharge pressure in the sub-pump SP using this low pressure, the hydraulic motor M and the sub-pump SP exhibit a pressure increasing function.
That is, the output of the hydraulic motor M is determined displacement volume to Q ₁ per rotation and the product of pressure P ₁ at that time. The output of the sub pump SP is determined by the product of the displacement volume Q ₂ per revolution and the discharge pressure P ₂ . In this embodiment, since the hydraulic motor M and the sub pump SP rotate coaxially, Q ₁ × P ₁ = Q ₂ × P ₂ must be satisfied. Therefore, for example, if the displacement volume to _{Q 1} hydraulic motor M has tripled i.e. _Q 1 = 3Q ₂ volume _{Q 2} displacement of the sub pump SP, this equation does _{3Q 2 × P 1 = Q 2} × the P _2. If both sides are divided by Q ₂ from this equation, 3P ₁ = P ₂ holds.
Therefore, by changing the tilt angle of the sub pump SP, by controlling the displacement volume Q _2, the output of the hydraulic motor M, it is possible to maintain the predetermined discharge pressure sub pump SP. In other words, the hydraulic pressure from the turning motor RM can be increased and discharged from the sub pump SP.

However, the tilt angle of the hydraulic motor M is controlled so as to keep the pressure in the passages 28 and 29 at the turning pressure or the brake pressure as described above. Therefore, when the pressure oil from the turning motor RM is used, the tilt angle of the hydraulic motor M is inevitably determined. In this way, the tilt angle of the sub-pump SP is controlled in order to exert the above-described pressure conversion function while the tilt angle of the hydraulic motor M is determined.
When the pressure in the passage 46 system becomes lower than the turning pressure or the brake pressure for some reason, the controller C closes the electromagnetic switching valve 50 based on the pressure signal from the pressure sensor 51 and turns the turning motor RM. Do not affect.
When pressure oil leaks in the connecting passage 46, the safety valve 52 functions to prevent the pressure in the passages 28 and 29 from becoming unnecessarily low, thereby preventing the turning motor RM from running away.

Next, a case where the boom cylinder BC is controlled will be described.
When the operation valve 16 is switched to operate the boom cylinder BC, an operation direction and an operation amount of the operation valve 16 are detected by a sensor (not shown) provided in the operation valve 16. An operation signal is input to the controller C.

  In response to the operation signal from the sensor, the controller C determines whether the operator is going to raise or lower the boom cylinder BC. When a signal for raising the boom cylinder BC is input to the controller C, the controller C keeps the proportional solenoid valve 36 in a normal state. In other words, the proportional solenoid valve 36 is kept in the fully open position. At this time, the controller C controls the rotational speed of the electric motor G and the tilt angle of the sub-pump SP while keeping the electromagnetic on-off valve 54 in the illustrated closed position.

On the other hand, when a signal for lowering the boom cylinder BC is input from the sensor to the controller C, the controller C calculates the lowering speed of the boom cylinder BC requested by the operator according to the operation amount of the operation valve 16, and is proportional. The electromagnetic valve 36 is closed, and the electromagnetic opening / closing valve 54 is switched to the open position.
If the proportional solenoid valve 36 is closed and the solenoid on-off valve 54 is switched to the open position as described above, the entire amount of return oil from the boom cylinder BC is supplied to the hydraulic motor M. However, if the flow rate consumed by the hydraulic motor M is less than the flow rate required to maintain the descending speed obtained by the operator, the boom cylinder BC cannot maintain the descending speed obtained by the operator. In such a case, the controller C sets a flow rate higher than the flow rate consumed by the hydraulic motor M based on the operation amount of the operation valve 16, the tilt angle of the hydraulic motor M, the rotation speed of the electric motor G, and the like. The opening degree of the proportional solenoid valve 36 is controlled so as to return to, and the lowering speed of the boom cylinder BC required by the operator is maintained.

On the other hand, when pressure oil is supplied to the hydraulic motor M, the hydraulic motor M rotates and the rotational force acts on the electric motor G that rotates coaxially. The rotational force of the hydraulic motor M is the electric motor G. Acts as an assist force against Therefore, power consumption can be reduced by the amount of rotational force of the hydraulic motor M.
On the other hand, the sub pump SP can be rotated only by the rotational force of the hydraulic motor M without supplying electric power to the electric motor G. At this time, the hydraulic motor M and the sub pump SP are the same as described above. The pressure conversion function is demonstrated.

Furthermore, the case where the turning operation of the turning motor RM and the lowering operation of the boom cylinder BC are simultaneously performed will be described.
When the boom cylinder BC is lowered while turning the turning motor RM as described above, the pressure oil from the turning motor RM and the return oil from the boom cylinder BC merge in the connection passage 46, and the hydraulic motor M To be supplied.
At this time, if the pressure in the introduction passage 47 rises, the pressure on the introduction passage 47 side rises accordingly. Even if the pressure becomes higher than the turning pressure or the brake pressure of the turning motor RM, the check valve 48 , 49 does not affect the turning motor RM.
If the pressure on the connection passage 46 side becomes lower than the turning pressure or the brake pressure as described above, the controller C closes the electromagnetic switching valve 50 based on the pressure signal from the pressure sensor 51.

Therefore, when the turning operation of the turning motor RM and the lowering operation of the boom cylinder BC are simultaneously performed as described above, the hydraulic motor M is controlled based on the required lowering speed of the boom cylinder BC regardless of the turning pressure or the brake pressure. The tilt angle can be determined.
In any case, the output of the sub-pump SP can be assisted by the output of the hydraulic motor M, and the flow rate discharged from the sub-pump SP is apportioned by the first and second proportional electromagnetic throttle valves 42 and 43 to obtain the first and second It can be supplied to the circuit systems S1 and S2.

On the other hand, when the electric motor G is used as a generator with the hydraulic motor M as a drive source, the tilt angle of the sub pump SP is set to zero and the load is almost unloaded, and the hydraulic motor M is caused to rotate the electric motor G. If the required output is maintained, the generator G can be functioned using the output of the hydraulic motor M.
Further, the generator 1 can generate power using the output of the engine E, or the generator G can generate power using the hydraulic motor M.

  Furthermore, since the check valves 44 and 45 are provided, and the electromagnetic switching valve 50 and the electromagnetic on-off valve 54 or the first and second on-off valves 58 and 59 are provided, for example, when the sub pump SP and the hydraulic motor M system break down, The first and second main pumps MP1, MP2 can be hydraulically separated from the sub pump SP and the hydraulic motor M. In particular, when the electromagnetic switching valve 50, the electromagnetic on-off valve 54, and the first and second on-off valves 58 and 59 are in a normal state, the solenoid switching valve 50, the electromagnetic on-off valve 54, and the first and second on-off valves 58 and 59 maintain the closed position by the spring force of the spring as shown in the drawing. Since the valve 36 also maintains the normal position that is the fully open position, even if the electric system fails, the first and second main pumps MP1 and MP2, the sub pump SP, and the hydraulic motor M system are hydraulically disconnected as described above. be able to.

  It can be used for construction machines such as power shovels.

MP1 1st main pump MP2 2nd main pumps 2-6 Operation valve S1 1st circuit system S2 2nd circuit system 7 and 18 Neutral flow path 9 and 20 Restriction PV1 Pilot pressure switching valve PV2 Pilot pressure switching valve 11 and 22 Pilot flow Roads 12 and 23 Regulators 14 to 17 Operation valves R1 and R2 Pressure reducing valve PL1 Pilot flow switching valve PL2 Pilot flow switching valve M Hydraulic motor 58 and 59 On-off valve PC1 Pilot control valve PC2 Pilot control valve G Generator C Controller E Engine PP pilot pump

Claims (3)

  A variable displacement pump, a circuit system connected to the variable displacement pump and provided with a plurality of operation valves, and a variable displacement pump of the variable displacement pump when all of the operation valves provided in the circuit system maintain a neutral position. A neutral flow path for guiding discharged oil to the tank, a throttle for generating a pilot pressure provided in the neutral flow path further downstream of the operation valve located on the most downstream side, and the most downstream operation valve and for generating a pilot pressure. The most downstream operation in a control device for a construction machine comprising a pilot flow path that guides the pressure generated between the throttle and a regulator that is connected to the pilot flow path and controls the tilt angle of the variable displacement pump A pilot pressure switching valve provided in a neutral flow path between the valve and the throttle for generating a pilot pressure and switchable between a fully open position and a closed or throttle position; A provided pressure reducing valve, a pilot flow path switching valve that opens and closes a bypass flow path that bypasses the pressure reducing valve, a hydraulic motor connected in parallel to the variable displacement pump with respect to the circuit system, and the variable displacement pump An on-off valve for opening and closing a flow path connecting the hydraulic motor and the pilot control valve for communicating the pilot pressure switching valve and the pilot chamber of the on-off valve with the neutral flow path or blocking the communication; A hybrid construction machine equipped with a generator linked to a hydraulic motor.   A variable displacement pump, a circuit system connected to the variable displacement pump and provided with a plurality of operation valves, and a variable displacement pump of the variable displacement pump when all of the operation valves provided in the circuit system maintain a neutral position. A neutral flow path for guiding discharged oil to the tank, a throttle for generating a pilot pressure provided in the neutral flow path further downstream of the operation valve located on the most downstream side, the most downstream operating valve and the throttle for generating a pilot pressure In the control device for a construction machine, comprising the pilot flow path for guiding the pressure generated between and a regulator connected to the pilot flow path and controlling the tilt angle of the variable displacement pump, the most downstream operation valve A pilot pressure switching valve provided in a neutral flow path between the valve and a throttle for generating a pilot pressure and capable of switching between a fully open position and a closed or throttle position, a pilot pressure source, A pilot flow path switching valve provided in the pilot flow path and switchable to a position connecting the neutral flow path and the regulator and a position connecting the pilot pressure source and the regulator; and the pilot pressure source A pressure reducing valve provided between the variable displacement pump and the flow path for connecting the variable displacement pump and the hydraulic motor. An open / close valve for opening and closing the pilot pressure switching valve and a pilot control valve for communicating the pilot chamber of the open / close valve with the pilot pressure source, and a generator linked to the hydraulic motor. Hybrid construction machine equipped.   The hybrid construction machine according to claim 1 or 2, wherein the pilot pressure switching valve is switchable between a throttle position and a fully open position.

Images