JP2007321972A - Power unit for construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power unit for a construction machine travelable even in a poor road surface condition and high in energy efficiency. <P>SOLUTION: The power unit for the construction machine traveling by supplying one traveling system actuator with an operating fluid discharged from a first pump P1 and supplying the other traveling system actuator with an operating fluid discharged from a second pump P2, is provided with an auxiliary pump P3 connected to the first and second pumps; a pair of pressure compensation valves 24, 25 controlling pressure led to the first and second pump side from the auxiliary pump; and a high pressure selector valve 26 selecting pilot pressure led to the pair of compensation valves. The high pressure selector valve selects higher pressure of the traveling system actuators to lead it to the pair of pressure compensation valves, controlling the operating fluid discharged from the auxiliary pump, by the pressure compensation valves, and uniting the operating fluid controlled by the pressure compensation valves, equivalently with the operating fluid discharged from the first and second pumps to lead the united operating fluid to both traveling system actuators. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power device for a construction machine such as a power shovel.

As a power device for a construction machine, for example, a power shovel can be cited, and the power shovel circuit configuration shown in Patent Document 1 is generally used. The main structure and operation of this power shovel will be described below.
As shown in FIG. 3, in this power shovel, the first pump P1 and the second pump P2 are linked to an engine that is a drive source, and hydraulic oil is discharged from both the pumps P1 and P2 by the rotation of the engine. I am doing so.

The first pump P1 is connected to the left travel valve 2 via the first pump passage 1 and the first tandem passage 1a. In the first tandem passage 1a, the turning valve 3 and the arm I speed valve are connected. 4. Boom II speed valve 5 and spare valve 6 are connected. However, the first parallel passage 7 is connected to the first pump passage 1, and the valves 3 to 6 are connected in parallel via the first parallel passage 7.
The second pump P2 is connected to the second pump passage 8 and the second tandem passage 8a. The second pump passage 8 includes a right travel valve 9, a bucket valve 10, and a boom I speed valve 11. The valve for arm II speed 12 is connected. However, the second pump passage 8 is connected to the second parallel passage 13, and the bucket valve 10 and the boom I speed valve 11 are connected in parallel via the second parallel passage 13.
The left travel valve 2 and the right travel valve 9 are valves that control the travel system actuators. By switching these valves 2 and 9, the travel system actuators can be operated independently on the left and right. it can. The valves other than the valves 2 and 9 are valves for controlling the actuator of the work machine system.

A distribution passage 14 is connected to the second pump passage 8, and the distribution passage 14 is led to the left travel valve 2. A switching valve 15 is provided in the distribution passage 14 so as to communicate or block the second pump P2 and the left travel valve 2.
In the figure, reference numeral 16 is a switching valve, 17 to 19 are relief valves, and 20 is a pilot pump. The pilot pump 20 discharges pilot pressure for switching each valve, the switching valve 15 and the switching valve 16, and the maximum pressure of the pilot line is set by the relief valve 19.
The relief valve 17 has a higher set pressure than the relief valve 18. Therefore, when the switching valve 16 is at the illustrated communication position, the set pressure of the relief valve 18 is the maximum pressure of the circuit, and when the switching valve 16 is at the shut-off position on the left side of the drawing, the set pressure of the relief valve 17 is set. Is the maximum pressure of the circuit.

Next, the operation of this power shovel will be described.
When operating the actuator of the work machine system with the excavator stopped, the first pump P1 is rotated and any one of the turning valve 3, the arm I speed valve 4, and the boom II speed valve 5 is turned on. Switch. Now, assuming that the arm I speed valve 4 is switched to operate the arm actuator, the hydraulic oil discharged from the first pump P1 passes through the first parallel passage 7 and the arm I speed valve 4 for the arm. While being guided to the actuator, the arm actuator can be operated by the hydraulic oil. At this time, when the arm I speed valve 4 is switched, the first pump passage 1 is shut off, and the first pump P1 and the left travel valve 2 are shut off.

In the above state, the second pump P2 is rotated and the bucket valve 10 is switched while keeping the switching valve 15 in the illustrated cutoff position. Then, the hydraulic oil discharged from the second pump P2 is guided to the bucket actuator via the second pump passage 8, the second tandem passage 8a, the second parallel passage 13, and the bucket valve 10, and is also generated by the hydraulic oil. The bucket actuator can be actuated.
If the arm I speed valve 4 and the arm II speed valve 12 are switched in a state where the hydraulic oil is discharged from the first and second pumps P1 and P2, the arm actuator can be controlled at the second speed. .
Thus, by rotating the first and second pumps P1 and P2 and switching the valve for controlling the actuator of the work implement system, the arm and boom can be controlled at the second speed, or the boom, arm and bucket can be controlled. Can be controlled at the same time.

On the other hand, when the actuator of the work machine system is controlled during traveling of the power shovel, in other words, when the traveling system and the work machine system are simultaneously controlled, the switching valve 15 is switched to the communication position on the left side in the drawing. When the second pump P2 is rotated and the left travel valve 2 and the right travel valve 9 are switched, the hydraulic oil discharged from the second pump P2 causes the second pump passage 8 and the right travel valve 9 to be switched. To the right traveling actuator via the distribution passage 14 and the left traveling valve 2. Thus, since the hydraulic oil discharged from the second pump P2 is guided to both actuators of the traveling system, the power shovel can travel.
In this state, if the first pump P1 is rotated and any one of the turning valve 3, the arm I speed valve 4, and the boom II speed valve 5 is switched, the operation is performed by the hydraulic oil discharged from the first pump P1. Mechanical actuators can be activated.

When the excavator is driven without controlling the actuator of the work implement system, the first and second pumps P1 and P2 are rotated while the switching valve 15 is kept at the illustrated cutoff position, and the left The travel valve 2 and the right travel valve 9 are switched. Then, the hydraulic oil discharged from the first pump P1 is guided to the left travel actuator, and the hydraulic oil discharged from the second pump P2 is guided to the right travel actuator, so that the power shovel can travel.
Hydraulic Pneumatic Handbook (Edited by Japan Society of Hydraulic and Pneumatics) Hydraulic Excavator Application Examples P638 and 639

In the power shovel, the hydraulic oil discharged from the first pump P1 is guided to the left travel actuator, and the hydraulic oil discharged from the second pump P2 is guided to the right travel actuator so that the power shovel travels. ing.
However, in construction sites that use power shovels, mud and bumps are scattered, and the road surface condition is often very poor. When a power shovel runs on such mud or uneven ground, there is a problem that the crawler gets stuck in mud or uneven and cannot get out of there.

In order to solve the above-described problem, it is conceivable to increase the operating force acting on the actuator of the traveling system so that the crawler can come out of the crawler even if it becomes muddy or uneven. In other words, it is conceivable to increase the capacities of both pumps P1, P2.
However, if the capacity of both pumps P1 and P2 is increased so that the vehicle can run even in poor road surface conditions, the load of the drive source becomes larger than necessary when operating the actuator of the work implement system. This time, there was a problem that the energy efficiency became very bad.

  An object of the present invention is to provide a power device for a construction machine that is capable of traveling even when the road surface condition is poor and that has high energy efficiency.

  The present invention includes a travel system actuator that operates independently on the left and right sides, a work machine system actuator, and a first pump and a second pump that selectively supply hydraulic oil to the travel system or work machine system actuator. It is premised on a power device for a construction machine that travels by supplying hydraulic oil discharged from the first pump to one traveling system actuator and supplying hydraulic oil discharged from the second pump to the other traveling system actuator. .

  On the premise of the above configuration, the first invention includes an auxiliary pump connected to the first and second pumps, a pair of pressure compensating valves for controlling the pressure guided from the auxiliary pump to the first and second pumps, A high-pressure selection valve that selects a pilot pressure that leads to a pair of pressure compensation valves, and the high-pressure selection valve selects the higher one of the actuators of the traveling system and guides it to the pair of pressure compensation valves, The hydraulic oil discharged from the auxiliary pump is controlled by the pressure compensation valve, and the hydraulic oil controlled by the pressure compensation valve is evenly merged with the hydraulic oil discharged from the first and second pumps, so that both actuators of the traveling system It is characterized by the point that leads

  The second invention includes a generator motor that rotates integrally with the auxiliary pump, and a power storage unit that stores electric power generated by the rotation of the generator motor, and inertia energy and potential energy act on the actuator of the work machine system. The passage on the return side is sometimes connected to the suction side of the auxiliary pump, and the inertial or positional energy is converted into electrical energy by rotating the auxiliary pump and generator motor with the return fluid from the actuator of the work equipment system. However, it is characterized in that the generator motor is rotated by the stored electrical energy and hydraulic oil is discharged from the auxiliary pump.

According to the first aspect of the present invention, the hydraulic oil discharged from the first and second pumps and the hydraulic oil discharged from the auxiliary pump are merged and guided to both the travel system actuators. Can be applied.
Therefore, even when the vehicle travels at a high speed or gets stuck in the mud, it can be easily pulled out from there.
Moreover, since the hydraulic oil discharged from the auxiliary pump can be merged as necessary, it is not necessary to increase the capacities of the first and second pumps more than necessary. Therefore, the load of the drive source can be reduced and the energy efficiency can be increased.

  In addition, since the pair of pressure compensation valves is controlled by the higher pressure of the traveling system actuators, even if a pressure difference occurs between both of the traveling system actuators, many of the lower pressure actuators There is no flow of hydraulic oil. Therefore, the hydraulic oil that merges with the first pump and the hydraulic oil that merges with the second pump can always be equal regardless of the pressure generated in the actuator of the traveling system, and the vehicle travels without being affected by the road surface condition. be able to.

  According to the second invention, inertial energy or potential energy is converted into electric energy by the return fluid from the actuator of the work machine system, while the generator motor and the auxiliary pump are rotated by the electric energy stored in the power storage unit. Therefore, energy efficiency can be further increased.

A first embodiment of the present invention will be described with reference to FIG.
In the first embodiment, as in the conventional circuit configuration, hydraulic oil is applied to the traveling system actuators that operate independently on the left and right sides, the working machine system actuators, and the traveling system or working machine system actuators. The first and second pumps are selectively supplied, and the hydraulic oil discharged from the first pump is supplied to one traveling system actuator, and the hydraulic oil discharged from the second pump is supplied to the other traveling system actuator. Assuming a power device for a construction machine that travels.
Since the first embodiment is based on the conventional circuit configuration, the conventional circuit configuration is denoted by the same reference numeral, and the detailed description of the same configuration as the conventional one is omitted.

  FIG. 1 shows a circuit configuration of a power shovel that is one of the power devices for construction machines. In this power shovel, an auxiliary pump P3 having an electric motor M as a drive source is connected to a passage 21. The passage 21 is branched and connected to a first joining passage 22 and a second joining passage 23, while the first joining passage 22 is connected to the first pump passage 1, and the second joining passage 23 is connected to the second pump passage 8. Is connected to each.

  A pair of pressure compensating valves 24 and 25 are provided in the first and second merging passages 22 and 23 which are the connection process between the first and second pumps P1 and P2 and the auxiliary pump P3. In addition, a high pressure selection valve 26 is connected to the first and second merging passages 22 and 23 and closer to the first and second pumps P1 and P2 than the pair of pressure compensation valves 24 and 25. The relationship between the high pressure selection valve 26 and the pair of pressure compensation valves 24 and 25 is as follows.

That is, the high pressure selection valve 26 selects the higher pressure of the first merging passage 22 and the second merging passage 23 and guides the selected pressure to the pair of pressure compensating valves 24 and 25 as a pilot pressure. ing.
The pressure compensation valve 24 is the first merging passage 22 and balances with the pressure on the auxiliary pump P3 side (passage 21 side) and the pilot pressure introduced from the high pressure selection valve 26. On the other hand, the pressure compensation valve 25 is the second merging passage 23, and balances with the pressure on the auxiliary pump P3 side (passage 21 side) and the pilot pressure introduced from the high pressure selection valve 26. Further, since the fixed throttles having the same area are provided on the upstream side of the pressure compensation valves 24 and 25, the hydraulic oil guided from the auxiliary pump P3 to the first merging passage 22 and the second merging passage from the auxiliary pump P3. The hydraulic fluid led to 23 is always equal.

  In the first embodiment, based on the operation signal transmitted from each operation lever 27, the controller C rotates the electric motor M, and the tilt angles of the first pump P1, the second pump P2, and the auxiliary pump P3. Is controlling.

Next, the operation of the first embodiment will be described.
When the excavator is driven without operating the work system actuator, the hydraulic oil is discharged by rotating the first and second pumps P1 and P2 while keeping the switching valve 15 in the illustrated cutoff position. In addition, the left travel valve 2 and the right travel valve 9 are switched. Then, the hydraulic oil discharged from the first pump P1 is guided to the left travel actuator, and the hydraulic oil discharged from the second pump P2 is guided to the right travel actuator, so that the power shovel travels.

  In order to cause the power shovel to travel at a high speed or escape from the mud from the above traveling state, the traveling operation lever 27 is fully operated when a large operating force is applied to the actuator of the traveling system. Then, the controller C that has received the operation signal rotates the electric motor M, and the auxiliary pump P3 rotates with the rotation of the electric motor M to discharge hydraulic oil.

At this time, the pressures of both the traveling actuators are guided as pilot pressures to the pair of pressure compensating valves 24 and 25 via the high pressure selection valve 26, and the pressure compensating valve 24 is based on the pilot pressure and the discharge pressure of the auxiliary pump P3. , 25 are balanced to compensate for the pressures in both merging passages 22,23. And since the fixed throttle of the same area is provided in the upstream of the pressure compensation valves 24 and 25, the hydraulic oil discharged from the auxiliary pump P <b> 3 passes from the passage 21 to the first joining passage 22 and the second joining passage 23. Equally distributed.
The hydraulic oil discharged from the first pump P1 and the auxiliary pump P3 merges in the first pump passage 1 and is guided to the left travel actuator, and the hydraulic oil discharged from the second pump P2 and the auxiliary pump P3 is They merge in the second pump passage 8 and are guided to the right traveling actuator.

  As described above, by combining the hydraulic oil discharged from the auxiliary pump P3 with the hydraulic oil discharged from the first and second pumps P1 and P2, a large operating force can be applied to the travel system actuator. Therefore, the excavator can be run at a high speed as necessary, and even when the crawler gets stuck in the mud, it can be easily escaped from there.

  In the case where the hydraulic oil discharged from the auxiliary pump P3 is joined and traveling, for example, it is assumed that the left crawler gets stuck in mud. Then, the pressure of the left traveling actuator becomes higher than the pressure of the right traveling actuator, and the pressures of the first pump passage 1 and the first joining passage 22 are the pressures of the second pump passage 8 and the second joining passage 23. Higher than. When the pressure of the first merging passage 22 becomes higher than the pressure of the second merging passage 23, the high pressure selection valve 26 selects the pressure of the first merging passage 22, and the pressure of the first merging passage 22 is set as the pilot pressure. It leads to a pair of pressure compensation valves 24 and 25. Accordingly, both the pressure compensating valves 24 and 25 are controlled by the pressure of the left travel actuator, and an equal amount of hydraulic fluid can be guided from the auxiliary pump P3 to the merging passages 22 and 23.

  In this way, if the pair of pressure compensating valves 24 and 25 are controlled by the higher pressure of the traveling system actuators, even if a pressure difference occurs between both of the traveling system actuators, the lower pressure actuator is controlled. A lot of hydraulic oil does not flow. Therefore, the hydraulic oil that merges with the first pump P1 and the hydraulic oil that merges with the second pump P2 can always be made equal regardless of the pressure generated in the actuator of the traveling system, without being affected by the road surface condition. You can travel.

In addition, in this 1st Embodiment, although the case where the power shovel was drive | working was demonstrated, the case where the actuator of a working machine system is act | operating, or the traveling system and a work machine system are controlled simultaneously Alternatively, the hydraulic oil discharged from the auxiliary pump P3 may be merged.
For example, when the traveling system and the work machine system are simultaneously controlled, if the hydraulic oil discharged from the auxiliary pump P3 is merged, even during simultaneous control, high-load work or high-speed traveling is performed. Can be.

According to the first embodiment, the hydraulic oil discharged from the first and second pumps P1 and P2 and the hydraulic oil discharged from the auxiliary pump P3 are merged and guided to both actuators in the traveling system. A sufficient operating force can be applied to the system actuator.
Therefore, even when the vehicle travels at a high speed or gets stuck in the mud, it can be easily pulled out from there.
Moreover, since the hydraulic fluid discharged from the auxiliary pump P3 can be merged as necessary, it is not necessary to increase the capacities of the first and second pumps P1 and P2 more than necessary. Therefore, the load of the drive source can be reduced and the energy efficiency can be increased.

A second embodiment of the present invention will be described with reference to FIG.
The circuit configuration of the second embodiment is characterized in that a regenerative circuit indicated by a two-dot chain line is connected to the circuit configuration of the first embodiment. The other circuit configurations are the same as those of the first embodiment. This is the same as the embodiment. Therefore, the same circuit configuration as that of the first embodiment is denoted by the same reference numeral, and here, the regenerative circuit will be mainly described.

  The boom actuator A shown in FIG. 2 divides the inside of the cylinder into a rod side chamber A1 and a piston side chamber A2 by a piston to which a rod is fixed. When the boom operation lever is operated to the lower side, the boom I speed valve 11 and the boom II speed valve 5 are switched to one side, and the first parallel path 7 and the second parallel path 13 are connected via the connection path 28. To communicate with the rod side chamber A1. At this time, the piston side chamber A2 communicates with the tank via the connection passage 29, and the rod contracts into the cylinder and lowers the load acting on the rod. On the other hand, when the boom operating lever is operated to the up side, the boom I speed valve 11 and the boom II speed valve 5 are switched to the other side, and the first parallel path 7 and the second parallel path 13 are connected to the connection path. It communicates with the piston side chamber A2 through 29. At this time, the rod side chamber A1 communicates with the tank via the connection passage 28, and the rod extends from the cylinder and increases the load acting on the rod. As described above, the boom actuator A switches the boom I speed valve 11 and the boom II speed valve 5 to expand and contract the rod and raise or lower the load, or hold the load. .

The connection passage 29 is connected to the suction side of the auxiliary pump P3 via a return flow path 30 and a suction side flow path 31. However, a regenerative switching valve S is provided between the return flow path 30 and the suction side flow path 31, and by switching the regenerative switching valve S, the return flow path 30 and the suction side flow path 31 communicate with each other. I try to block it.
Further, the discharge side flow path 32 is connected to the discharge side of the auxiliary pump P3 and the regenerative switching valve S is switched so that the discharge side flow path 32 communicates with the passage 21 or communicates with the tank. Like to do.

  The regenerative switching valve S is a valve that can be switched to three positions, and the discharge side flow path 32 communicates with the tank at the center position. Further, when the regenerative switching valve S is switched to the upper position in the drawing, the tank and the suction side flow path 31 are communicated, and the discharge side flow path 32 and the passage 21 are communicated. On the other hand, when the regenerative switching valve S is switched to the lower position in the drawing, the discharge side flow path 32 and the tank are communicated, and the return flow path 30 and the suction side flow path 31 are communicated.

  The regenerative switching valve S is switched by the pilot pressure acting on both ends. The controller C controls the pilot pressure. That is, the controller C controls the pilot solenoid valves 33 and 34 based on the operation signal of each operation lever 27 and controls the pilot pressure acting on the regeneration switching valve S to switch the regeneration switching valve S. Yes.

A short-circuit passage 35 is connected between the suction-side passage 31 and the discharge-side passage 32, and a two-position switching valve 36 is provided in the short-circuit passage 35. The two-position switching valve 36 normally holds a position where the suction side flow path 31 and the discharge side flow path 32 are communicated with each other by the spring force of a spring. It switches to the position which interrupts | blocks 31 and the discharge side flow path 32. FIG. The pilot pressure for switching the two-position switching valve 36 is controlled by the pilot solenoid valve 34. That is, at the same time when the regenerative switching valve S is switched to the upper position in the figure, the two-position switching valve 36 is switched to the left position in the figure.
Further, a power converter G and a power storage unit U that stores electric energy generated by the rotation of the generator motor MG are connected to the generator motor MG that is a drive source of the auxiliary pump P3. When the generator motor MG is driven, the generator motor MG is driven by the electric energy stored in the power storage unit U.

Next, the operation of the second embodiment will be described.
When the load is lowered from the state in which the load is applied to the boom actuator A, the boom operation lever is operated to the lower side to switch the boom I speed valve 11 or the boom II speed valve 5. Then, the controller C that receives the operation signal rotates the first pump P1 or the second pump P2 and controls the pilot electromagnetic valve 33 to switch the regenerative switching valve S to the lower position in the figure. Accordingly, the hydraulic oil is led from the first pump P1 or the second pump P2 to the rod side chamber A1 via the boom II speed valve 5 and the boom I speed valve 11, and the return oil from the piston side chamber A2 is connected. It is guided to the suction side of the auxiliary pump P3 via the passage 29 → the return flow path 30 → the regeneration switching valve S → the suction side flow path 31. Here, the connection passage 29 is a passage on the return side when inertia energy or potential energy acts on the actuator of the work machine system.

  The auxiliary pump P3 is rotated by the return oil guided from the return side passage, and the generator motor MG is rotated along with the rotation of the auxiliary pump P3. The return oil that has rotated the auxiliary pump P3 is returned to the tank via the discharge-side flow path 32 and the regeneration switching valve S. Thus, when lowering the boom actuator A, the power conversion device G converts the inertial energy and the potential energy acting on the boom actuator A into electric energy, and the electric energy is transferred to the power storage unit U. It can be charged.

On the other hand, as already described in the first embodiment, when the hydraulic oil discharged from the auxiliary pump P3 is merged with the first pump P1 and the second pump P2 to run the power shovel, each operation lever 27 Based on the operation signal, the controller C controls the pilot solenoid valve 34 and the generator motor MG.
Under the control of the controller C, the generator motor MG is rotated by the electric energy stored in the power storage unit U, and the auxiliary pump P3 rotates and discharges hydraulic oil as the generator motor MG rotates.

  At this time, the regenerative switching valve S is switched to the upper position in the figure and the two-position switching valve 36 is switched to the left position in the figure by the pilot pressure introduced from the pilot solenoid valve 34. Accordingly, the hydraulic oil discharged from the auxiliary pump P3 is guided to the discharge side flow path 32 → the regenerative switching valve S → the passage 21, and the first merging passage 22 and the second merging passage through both pressure compensation valves 24 and 25. 23 evenly. Then, the hydraulic oil discharged from the auxiliary pump P3 merges the same amount in the first pump P1 and the second pump P2, and the merged hydraulic oil is guided to both travel actuators.

Even when the hydraulic oil discharged from the auxiliary pump P3 is guided to the work machine system actuator or to the travel system and work machine system actuators at the same time, the pumps P1 and P2 are joined together in the same manner as described above. That's fine.
Further, when a pressure difference occurs between the two travel actuators, that is, when a difference occurs in the pressure between the first joining passage 22 and the second joining passage 23, the higher pressure is used as the pilot pressure. As described above, the pressure compensation valves 24 and 25 are guided to the pressure compensation valves 24 and 25, and the pressure compensation valves 24 and 25 are controlled by the pilot pressure.

According to the second embodiment, inertial energy or potential energy is converted into electric energy by the return fluid from the boom actuator A, while the generator motor MG and the auxiliary pump P3 are rotated by the electric energy stored in the power storage unit U. As a result, energy efficiency can be further improved.
In the second embodiment, the inertia energy and potential energy acting on the boom actuator are converted into electric energy. However, the work machine system actuator is subject to inertia energy or potential energy. Any actuator may be used as long as it is present. Therefore, the actuator of the work machine system is not limited to the cylinder but may use a motor.

Moreover, although each pump in the said 1st, 2nd embodiment can make discharge amount variable by controlling a tilt angle with a controller, you may use a constant discharge pump.
In the first and second embodiments, the circuit configuration of the power shovel has been described. However, the present invention is not limited to the power shovel, and includes a travel system and work machine system actuators. It can be widely used in power units operated by separate pumps.

It is a circuit diagram of a 1st embodiment. It is a circuit diagram of a 2nd embodiment. It is a circuit diagram used for the power unit of the conventional construction machine.

Explanation of symbols

24, 25 Pressure compensation valve 26 High pressure selection valve 30 Return flow path G Power converter M Electric motor MG Generator motor P1 First pump P2 Second pump P3 Auxiliary pump U Power storage unit

Claims (2)

  A travel system actuator that operates independently on the left and right; a work machine system actuator; and a first pump and a second pump that selectively supply hydraulic oil to the travel system or work machine system actuator. In the power equipment for a construction machine that travels by supplying the hydraulic oil discharged from the pump to one traveling system actuator and supplying the hydraulic oil discharged from the second pump to the other traveling system actuator, the first and second An auxiliary pump connected to the pump, a pair of pressure compensating valves for controlling the pressure led from the auxiliary pump to the first and second pumps, and a high pressure selecting valve for selecting the pilot pressure led to the pair of pressure compensating valves are provided The high pressure selection valve selects the higher pressure of the traveling system actuators and guides it to a pair of pressure compensation valves. The hydraulic oil discharged from the auxiliary pump is controlled, and the hydraulic oil controlled by the pressure compensation valve is evenly merged with the hydraulic oil discharged from the first and second pumps and guided to both actuators of the traveling system. Power equipment for construction machinery.   A generator motor that rotates integrally with the auxiliary pump, and a power storage unit that stores electric power generated by the rotation of the generator motor, and becomes a return side when inertial energy or potential energy acts on the actuator of the work machine system The passage is configured to be connected to the suction side of the auxiliary pump, and the auxiliary pump and the generator motor are rotated by the return fluid from the actuator of the work machine system to convert the inertial energy or potential energy into electric energy and store the electric energy, 2. The power device for a construction machine according to claim 1, wherein the generator motor is rotated by the stored electric energy and the hydraulic oil is discharged from the auxiliary pump.

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