JP3647319B2 - Hydraulic drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic drive device, and more particularly, to a hydraulic drive device such as a construction machine that can save energy and realize excellent operability.
[0002]
[Prior art]
In recent years, as a hydraulic drive system including construction equipment such as hydraulic excavators and wheel loaders and hydraulic working machines such as forklifts, a generator in addition to the engine is provided as a power source to reduce engine burden and fuel consumption rate. The so-called hybrid type is being developed.
[0003]
As a hybrid hydraulic drive device, Japanese Utility Model Laid-Open No. 5-48501 discloses that electric energy generated by a generator during low-load operation is stored in a battery, and the electric energy is extracted during high-load operation to reduce the burden on the engine. An apparatus is described which is adapted to do so. Japanese Patent Laid-Open No. 8-60705 discloses a construction machine in which a hydraulic cylinder is driven by a hydraulic pump directly driven by an engine and a hydraulic pump driven by a motor connected to a generator and a storage battery. An output support device is described. Japanese Patent Laid-Open No. 10-103112 discloses a hydraulic drive apparatus having a turning system driven by a turning pump motor connected to a pressure accumulating means in addition to a hydraulic actuator driven by a hydraulic pump connected to an engine. Is described.
[0004]
[Problems to be solved by the invention]
According to the technique of the above-mentioned publication, an actuator that is a drive portion of a hydraulic drive device is driven by a hydraulic pump directly connected to an engine or a pressure accumulating means. Therefore, when the arm or boom of the hydraulic excavator is moved, a smooth operation following the movement of the operation lever can be realized. However, on the other hand, there is a problem that energy efficiency is lowered by using a hydraulic pump directly connected to an engine or the like to drive the actuator. Both operability and relatively high energy efficiency could not be satisfied.
[0005]
Therefore, a main object of the present invention is to provide a hydraulic drive device that is relatively energy efficient while ensuring good operability of the operating portion.
[0006]
[Means for Solving the Problems]
To achieve the above object, a hydraulic drive apparatus according to claim 1 is an engine, a first hydraulic pump driven by the engine, and a first hydraulic pump connected to the first hydraulic pump via a control valve. Hydraulic actuator, power storage means for storing electrical energy, operation for converting mechanical energy received from the engine into electrical energy and supplying the electrical energy to the power storage means, and converting the electrical energy received from the power storage means into mechanical energy Energy conversion means capable of selectively performing the operation of converting and supplying the first hydraulic pump; Configured to receive supply of electrical energy from both the energy conversion means and the power storage means; and And a first electric motor that is supplied with electric energy from at least one of the energy conversion unit and the power storage unit and serves as a drive source for the operation unit.
[0007]
According to the hydraulic drive device of the first aspect, since the first hydraulic pump driven by the engine is connected to the first hydraulic actuator via the control valve, the operation is smoothly performed following the movement of the operation lever. It is possible to realize good operability with respect to an operating part such as an arm or boom of a hydraulic excavator that is necessary.
[0008]
In addition, since the first electric motor that receives the supply of electric energy from at least one of the energy conversion means and the power storage means serves as a drive source for the operation unit, for example, a bucket of a hydraulic excavator, a turning system, a traveling system, etc. By using the first electric motor as the drive source for the operation unit that does not require high operability, the energy efficiency can be improved as compared with the prior art.
[0009]
In other words, in the hydraulic drive device according to the first aspect, the operation unit that requires good operability is driven by the first hydraulic pump, and the drive source of the operation unit that does not require much operability is the first motor. By doing so, it is possible to achieve relatively high energy efficiency while ensuring good operability of the operating part.
[0010]
In addition, since the operating unit is divided into one driven by the first hydraulic pump and one driven by the first electric motor, these can be made relatively small to be installed separately in different places. . For example, by arranging the first hydraulic pump in the main housing of the hydraulic drive device and installing the first electric motor in the vicinity of the corresponding operating unit, a large space is not required in one place, and the size is small. The hydraulic drive apparatus can be provided.
[0011]
Further, the energy conversion means converts the mechanical energy received from the engine into electrical energy and supplies it to the power storage means, and the operation converts the electrical energy received from the power storage means into mechanical energy and supplies it to the first hydraulic pump Therefore, when the load on the first hydraulic pump side is low, the surplus torque of the engine is used to generate electric power with the energy conversion means to store electric energy in the power storage means, and the first hydraulic pressure is stored. When the load on the pump side is high, the energy conversion means uses the electric energy stored in the power storage means as a power source, and the energy conversion means performs torque assist of the first hydraulic pump as a motor, thereby smoothing and reducing the load on the engine. Is possible. Therefore, the engine may be of a size that can share the average output, and it is not necessary to have a large engine that can handle the maximum output, reducing the engine size and reducing exhaust gas and noise. Energy saving can be achieved.
[0012]
The hydraulic drive apparatus according to claim 2 is characterized in that electric energy generated by regenerative control of the first electric motor is stored in the power storage means.
[0013]
According to the second aspect, the electric energy generated by the regenerative control of the first electric motor is stored in the power storage means, so that the energy efficiency can be further improved.
[0014]
The hydraulic drive apparatus according to claim 3 further includes a second hydraulic pump driven by the first electric motor and a second hydraulic actuator driven by the second hydraulic pump. It is a feature.
[0015]
According to the third aspect, since the second hydraulic actuator is driven by the second hydraulic pump driven by the first electric motor, it is possible to give a large thrust when it is necessary to linearly move the operating portion. In addition, the structure is simpler than converting rotational motion into linear motion with a rack and pinion.
[0016]
According to a fourth aspect of the present invention, the first electric motor, the second hydraulic pump, and the second hydraulic actuator are integrally configured.
[0017]
According to the fourth aspect, since the first electric motor, the second hydraulic pump, and the second hydraulic actuator are integrally configured, it is possible to reduce the size and weight of the first electric motor, the second hydraulic actuator, and the second hydraulic actuator. When it is not necessary to operate the engine, the corresponding first electric motor and second hydraulic pump are stopped, so that excess pressure oil can be prevented from being discarded. Therefore, energy efficiency can be further increased. Further, it is not necessary to provide a pipe connecting the second hydraulic pump and the second hydraulic actuator, so that the structure is simplified and the probability of oil leakage and the like can be reduced.
[0018]
According to a fifth aspect of the present invention, there is provided a hydraulic drive device including a second electric motor that receives supply of electric energy from at least one of the energy conversion means and the power storage means, and a third hydraulic pressure driven by the second electric motor. And a pump, wherein the pressure oil from the third hydraulic pump is supplied between the first hydraulic pump and the control valve.
[0019]
According to claim 5, since the pressure oil from the third hydraulic pump is supplied between the first hydraulic pump and the control valve, the pressure oil pressure in this portion can be kept constant. The operation start position of the operation lever does not differ depending on the load on the first hydraulic actuator, and the first actuator always starts to move from a certain operation lever position, improving operability. In addition, the operation start position of the operation lever can be kept constant with a small amount of loss, rather than simply compensating for fluctuations in the load on the first hydraulic actuator with torque assist by the energy conversion means.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is a schematic diagram showing a schematic configuration of an excavator that is a hydraulic drive device according to a first embodiment of the present invention. In FIG. 1, the excavator 1 includes a lower traveling body 2, an upper swing body 3, and an excavation attachment 4.
[0022]
The lower traveling body 2 has left and right crawler frames 5 and crawlers 6 (both shown only on one side), and left and right running motors 38 and a running speed reducer 39 (both shown only on one side). is doing. The travel speed reducer 39 decelerates the rotation of the travel motor 38 and transmits it to the travel mechanism.
[0023]
The upper swing body 3 includes a swing frame 8, a cabin 9, and the like. The revolving frame 8 rotates an engine 10 as a power source, a generator 11 and a hydraulic pump 20 driven by the engine 10, a battery 32, a hydraulic oil tank 14, a control valve 21, and the upper revolving body 3. A turning electric motor 36 for rotating the turning electric motor 36 and a turning speed reducer 37 for reducing the rotation of the turning electric motor 36 and transmitting it to the turning mechanism (turning gear) are installed. In addition, a control unit (not shown) including an inverter 31 (see FIG. 2) and the like is provided in the upper swing body 3.
[0024]
The excavation attachment 4 includes a boom 17, a boom cylinder 23 that extends and retracts to raise and lower the boom 17, an arm 19, an arm cylinder 22 that rotates the arm 19, a bucket 24, and a bucket cylinder that rotates the bucket 24. 35. In addition, a bucket motor 33 and a bucket hydraulic pump (hereinafter referred to as “bucket pump”) 34 driven by the bucket motor 35 are attached to the bucket cylinder 35. The bucket motor 33, the bucket pump 34, and the bucket cylinder 35 are integrated as will be described later.
[0025]
Next, the drive system of the shovel 1 will be described with reference to FIG. FIG. 2 is a block diagram schematically showing the drive system of the shovel 1. As shown in FIG. 2, the generator 11 and the hydraulic pump 20 are both attached to the output shaft of the engine 10. Then, the pressure oil from the hydraulic pump 20 is supplied to the arm cylinder 22 and the boom cylinder 23 via the control valve 21. Thereby, the arm 19 and the boom 17 can be moved to a predetermined position at an arbitrary speed by operating the operation lever to control the control valve 21.
[0026]
As described above, in the excavator 1 of the present embodiment, the arm 19 and the boom 17 that are required to have excellent operability to smoothly follow the lever operation of the operator are supplied with pressure from the hydraulic pump 20 without using an electric motor or the like. It is driven by oil. Therefore, the operator can accurately operate the delicate movements of the arm 19 and the boom 17.
[0027]
The generator 11 generates AC power from the output torque of the engine 10 as power generation means when the hydraulic pump 20 side is low in load and supplies it to the inverter 31. On the other hand, when the hydraulic pump 20 side is high in load, the battery 32 functions as an electric motor. The hydraulic pump 20 is driven by converting the electrical energy from the power into torque. Switching between the low load operation and the high load operation may be performed based on the product of the pressure oil pressure and the flow rate measured at the subsequent stage of the hydraulic pump 20 or manually by control of a control unit (not shown).
[0028]
An inverter 31 is connected to the generator 11. The inverter 31 converts the AC power generated by the generator 11 into DC power and stores it in the battery 32, and the AC power generated by the regenerative action of the motors 33, 36, and 38 connected to the inverter 31 is converted to DC power. The regenerative charging action stored in the battery 32 is converted to the above and performed.
[0029]
Further, the inverter 31 converts the electric energy stored in the battery 32 into alternating current and supplies it to the electric motors 33, 36, and 38 and / or the generator 11. , 38 performs each of the supply operations. When performing these two actions, the inverter 31 can change the frequency of the alternating current to an arbitrary value in accordance with a command from the control unit, thereby controlling the rotational speed of the electric motors 33, 36, and 38. Can be done.
[0030]
Three electric motors 33, 36 and 38 are connected to the inverter 31. As described above, the bucket motor 33 is configured as an integral actuator together with the bucket pump 34 and the bucket cylinder 35. The turning electric motor 36 and the traveling electric motor 38 are connected to a turning reduction gear 37 and a traveling reduction gear 39, respectively. These three electric motors 33, 36, and 38 are controlled on / off, rotation speed, and rotation direction by the operation of the operator.
[0031]
As described above, in the excavator 1 of the present embodiment, the bucket 24, the turning mechanism, and the traveling mechanism that do not require excellent operability that smoothly follows the lever operation of the operator are driven via the electric motors 33, 36, and 38. Like to do. Therefore, the electric energy of the battery 32 stored using the surplus torque of the engine 10 can be used effectively, and the excavator 1 can be operated with high energy efficiency.
[0032]
Next, the operation of the excavator 1 will be described. When the hydraulic pump 20 side is under low load, the generator 11 performs a power generating action when the engine 10 is operated, and the generated AC power is supplied to the motors 33, 36, and 38 via the inverter 31, thereby driving these. It becomes possible. At the same time, since the hydraulic pump 20 is driven by the engine 10, the arm cylinder 22 and the boom cylinder 23 can be appropriately moved by operating the control valve 21.
[0033]
The electric motors 33, 36, and 38 are driven by AC power supplied from the generator 11 via the inverter 37 when the total load on these is small. At this time, AC power generated by the generator 11 is converted into DC power by the inverter 31 and stored in the battery 32. When the arm cylinder 22 and the boom cylinder 23 are not used as when the excavator 1 is running, for example, when the stored power of the battery 32 is sufficient and the total load on the motors 33, 36, and 38 is small, the engine 10 may be reduced or the engine 10 may be stopped to supply power to the motors 33, 36, and 38 only from the battery 32. Accordingly, it is possible to prevent the engine 10 from operating wastefully, reduce noise and exhaust gas, and further reduce the fuel consumption rate.
[0034]
On the other hand, when the total load of the electric motors 33, 36, and 38 becomes larger than a predetermined value, the accumulator of the AC power generated by the generator 11 to the battery 32 is stopped, and the driving energy of the electric motors 33, 36, and 38 is used. Not only the power supplied from the generator 11 but also the power stored in the battery 32 is used together if necessary.
[0035]
Thus, the operation of the inverter 31 is switched depending on whether or not the total load of the electric motors 33, 36, and 38 is larger than a predetermined value. This switching is based on the product of the current flowing through the electric motors 33, 36, and the voltage thereof. Or manually under the control of the control unit.
[0036]
Further, during operation, the electric motors 33, 36, and 38 can act as a generator (regenerative action) using their potential energy and kinetic energy, and the regenerative power generated thereby can be stored in the battery 32. In particular, since the turning electric motor 36 can store a large amount of kinetic energy at the time of turning acceleration, the energy regeneration effect at the time of deceleration is high.
[0037]
Next, when the hydraulic pump 20 side is at a high load, the generator 11 functions as an electric motor, converts electric energy received from the inverter 31 via the battery 32 into torque, and drives the hydraulic pump 20. That is, the hydraulic pump 20 is driven not only by the engine output torque but also by the torque from the generator 11. As a result, even when the output of the engine 10 is relatively small, the hydraulic pump 20 can cope with a relatively large load.
[0038]
At this time, since no power is supplied from the generator 11 to the inverter 31, the electric motors 33, 36, and 38 are driven by the electric power supplied from the battery 32.
[0039]
That is, in the excavator 1 of the present embodiment, as shown in FIG. 3, the output energy of the engine 10 is kept constant, and the total load (working energy) of the hydraulic pump 20 and the electric motors 33, 36, and 38 is kept constant. The battery 32 is charged when the value is smaller than the value, and the battery 32 is discharged when the work energy is larger than a certain value and used as drive energy for the hydraulic pump 20 and / or the electric motors 33, 36, and 38.
[0040]
Thus, according to the shovel 1 of the present embodiment, since the hydraulic pump 20 driven by the engine 10 is connected to the arm cylinder 22 and the boom cylinder 23 that are hydraulic actuators via the control valve 21, the operation lever It is possible to realize good operability with respect to the arm 19 and the boom 17 that need to be smoothly operated following the movement of the arm 19. In addition, since the electric motors 33, 36, and 38 that are supplied with electric energy from the generator 11 and / or the battery 32 serve as driving sources for the bucket 24, the turning mechanism, and the traveling mechanism, the energy efficiency is improved as compared with the conventional case. Will be able to. That is, in the excavator 1 of the present embodiment, the arm 19 and the boom 17 that are required to have good operability are driven by the hydraulic pump 20, and the bucket 24, the turning mechanism, and the traveling mechanism that are not required to have good operability are driven. By using the electric motors 33, 36, and 38 as the source, it is possible to achieve relatively high energy efficiency while ensuring good operability of the arm 19 and the boom 17.
[0041]
Further, not all the operating parts are driven by the hydraulic pump 20 as in the prior art, but the bucket 24, the turning mechanism and the traveling mechanism are driven by the electric motors 33, 36, 38, so that the hydraulic pump 20 and The electric motors 33, 36, and 38 can be relatively small and installed separately in different places. In the present embodiment, the hydraulic pump 20 is disposed in the upper swing body 3 that is the main housing of the excavator 1, the bucket motor 33 is disposed in the vicinity of the arm, and the traveling motor 38 is disposed in the lower traveling body 2. The excavator 1 can be made relatively small without requiring a large space in the upper swing body 3.
[0042]
In the present embodiment, the bucket cylinder 35 is driven not via the electric motor 33 but via the bucket pump 34. Therefore, the bucket 24 that performs the linear motion can be moved with a relatively large thrust, compared to the case where the rotational motion is converted into the linear motion by a rack and pinion or the like. Further, as a mechanism for linearly moving the bucket 24, the structure is simpler than using a rack and pinion.
[0043]
Next, the above-described integrated actuator of the electric motor 33, the bucket pump 34, and the bucket cylinder 35 will be described with reference to FIGS. 4 is a side view of the integrated actuator, and FIG. 5 is a circuit diagram thereof.
[0044]
As shown in these drawings, the bucket pump 34 is configured as a bidirectional pump in which the oil discharge direction changes according to the rotation direction of the electric motor 33, and both side discharge ports of the pump 34 are connected via pipe lines 41 and 42. The bucket cylinder 35 is connected to the head side and the rod side oil chamber.
[0045]
In FIG. 5, 43 is a relief valve, 44 is an oil tank, 45 is an automatic switching valve provided between the pump 34 and the oil tank 44, 46 is an operation check valve, and 47 is provided between both side pipe lines 41 and 42. The manual open / close valve 48 is a slow return valve.
[0046]
If such an integrated actuator is used, the entire unit can be made smaller and lighter than when the electric motor 33 and the hydraulic pump 34 are provided separately. This is advantageous for mounting on the excavation attachment 4. When the bucket cylinder 35 is stopped, the electric motor 33 and the hydraulic pump 34 can be stopped so that excess pressure oil is not discarded. Therefore, energy efficiency can be further increased. Further, it is not necessary to provide a pipe connecting the hydraulic pump 34 and the bucket cylinder 35, so that the structure is simplified and the probability of oil leakage or the like can be reduced.
[0047]
Next, an excavator according to a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a schematic diagram showing a schematic configuration of an excavator which is a hydraulic drive device according to the second embodiment of the present invention. In FIG. 6, the same components as those in FIG. Excavator 50 of the present embodiment is configured basically in the same manner as that of the first embodiment except that inverter 31 and control valve 21 are connected by a confluence hydraulic circuit 53. ing. In order to simplify the drawing, the illustration of the bucket motor 33, the bucket pump 34, and the bucket cylinder 35 is omitted in FIG.
[0048]
In the present embodiment, the merging hydraulic circuit 53 is provided with an electric motor 51, a hydraulic pump 52 and a check valve 54, and pressure oil from the hydraulic pump 52 is supplied to the hydraulic pump 20, the control valve 21, and the hydraulic pump 20 according to the load of the hydraulic pump 20. I am trying to supply it in between. At this time, as described in the first embodiment, the load on the hydraulic pump 20 side is controlled by the control of a control unit (not shown) based on the product of the pressure oil pressure and the flow rate measured at the subsequent stage of the hydraulic pump 20. It is only necessary to measure and give a signal to the electric motor 51 so that the corresponding pressure oil is supplied between the hydraulic pump 20 and the control valve 21.
[0049]
In this way, when an amount of pressure oil corresponding to the load of the hydraulic pump 20 is supplied from the hydraulic pump 52 between the hydraulic pump 20 and the control valve 21, the operator operates the arm cylinder 22 or the boom cylinder 23. Therefore, the operation start position of the operation lever for making the operation lever can always be kept constant.
[0050]
This point will be described with reference to FIG. FIG. 7 is a graph showing the relationship between the operating lever position and the cylinder speed. In FIG. 7, a curve 71 is a curve 73 when the load on the boom cylinder 23 is relatively large in the first embodiment, and a curve 72 is a curve 73 when the load on the boom cylinder 23 is relatively small in the first embodiment. Shows the relationship between the operating lever position and the cylinder speed in the present embodiment.
[0051]
As apparent from FIG. 7, in the first embodiment, the position of the operation lever corresponding to the start of the operation of the boom cylinder 23 differs depending on the load on the boom cylinder 23. The boom cylinder 23 will not start to operate unless it is moved greatly.
[0052]
On the other hand, in the present embodiment, an amount of pressure oil corresponding to the load of the hydraulic pump 20 is supplied from the hydraulic pump 52 between the hydraulic pump 20 and the control valve 21, so that the pressure in this portion is increased. Since the oil pressure can be kept constant, the operation start position of the operation lever for the operator to operate the boom cylinder 23 can always be kept constant. Therefore, the operator can always operate the operation lever with the same feeling regardless of the load on the boom cylinder 23. In order to keep the operation start position of the operation lever constant, it is conceivable to compensate for fluctuations in the load on the hydraulic pump 20 side with torque assist to the hydraulic pump 20 by using the generator 11 as an electric motor. In the embodiment, by directly supplying the pressure oil to the cylinders 22 and 23, it is possible to reliably keep the operation start position of the operation lever constant with less loss than this means.
[0053]
Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made. For example, in the above-described embodiment, an AC generator is used as a generator, but a DC generator may be used. In that case, you may connect a generator and a battery directly, without passing through an inverter. Further, the bucket motor 33, the bucket pump 34, and the bucket cylinder 35 are not necessarily integrated, and may be configured as separate bodies. As the battery 32, a secondary battery such as a lithium ion battery is usually used. However, a capacitor may be used, or these may be used in combination.
[0054]
In addition, the present invention replaces a backhoe type excavating as shown in FIG. 1 as an excavator or excavation attachment with another work tool (for example, a soil removal board or a crusher) instead of the bucket. It can be applied to excavators equipped with a loading type that excavates from one side to the other, excavators that use wheels instead of crawlers as lower traveling bodies, and hydraulic work such as wheel loaders and other construction equipment and forklifts The present invention can be widely applied to hydraulic drive devices including machines.
[0055]
【The invention's effect】
As described above, according to the hydraulic drive device of the first aspect, the operation unit that requires good operability is driven by the first hydraulic pump, and the drive source of the operation unit that does not require much operability is provided. By using the first electric motor, it is possible to achieve relatively high energy efficiency while ensuring good operability of the operating unit.
[0056]
In addition, since the operating unit is divided into one driven by the first hydraulic pump and one driven by the first electric motor, these can be made relatively small to be installed separately in different places. .
[0057]
Furthermore, since the burden on the engine can be smoothed and reduced, the engine need only be of a size that can share the average output, and need not be large enough to support the maximum output. The engine size can be reduced to reduce the exhaust gas and noise and save energy.
[0058]
According to the hydraulic drive device of the second aspect, the electric energy generated by the regenerative control of the first electric motor is stored in the power storage means, so that the energy efficiency can be further improved.
[0059]
According to the hydraulic drive device of the third aspect, it is possible to give a large thrust when the operation portion needs to be linearly moved, and the structure is simpler than converting the rotational motion to the linear motion by a rack and pinion or the like. .
[0060]
According to the hydraulic drive device of the fourth aspect, since the first electric motor, the second hydraulic pump, and the second hydraulic actuator are integrally configured, it is possible to reduce the size and weight of the first electric motor, the second hydraulic pump, and the second hydraulic actuator. When it is not necessary to operate the second hydraulic actuator, the corresponding first electric motor and second hydraulic pump can be stopped so that excess pressure oil is not discarded. Therefore, energy efficiency can be further increased. Further, it is not necessary to provide a pipe connecting the second hydraulic pump and the second hydraulic actuator, so that the structure is simplified and the probability of oil leakage and the like can be reduced.
[0061]
According to the hydraulic drive device of claim 5, the pressure oil from the third hydraulic pump is supplied between the first hydraulic pump and the control valve, so that the pressure of the pressure oil in this portion is kept constant. Therefore, the operation start position of the operation lever does not differ depending on the load on the first hydraulic actuator, and the first actuator always starts to move from a certain operation lever position, thereby improving the operability.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a schematic configuration of an excavator which is a hydraulic drive device according to a first embodiment of the present invention.
2 is a block diagram schematically showing a drive system of the shovel shown in FIG. 1. FIG.
FIG. 3 is a graph showing a relationship between engine output and working energy in the excavator shown in FIG. 1;
4 is a side view of an integrated actuator of an electric motor, a bucket pump, and a bucket cylinder used in the excavator shown in FIG. 1. FIG.
5 is a circuit diagram of an integrated actuator of the electric motor, bucket pump, and bucket cylinder shown in FIG. 4;
FIG. 6 is a schematic diagram showing a schematic configuration of an excavator which is a hydraulic drive device according to a second embodiment of the present invention.
FIG. 7 is a graph showing a relationship between an operation lever position and a cylinder speed in the shovels according to the first and second embodiments of the present invention.
[Explanation of symbols]
1 Excavator
2 Lower traveling body
3 Upper swing body
4 Drilling attachment
8 Swivel frame
9 cabin
10 engine
11 Generator
17 Boom
19 Arm
20 Hydraulic pump
21 Control valve
22 Arm cylinder
23 Boom cylinder
24 buckets
31 Inverter
32 battery
33 Electric motor for bucket
34 Bucket pump
35 bucket cylinder
36 Electric motor for turning
37 Swivel reducer
38 Electric motor for running
39 Travel reducer

Claims (5)

Engine,
A first hydraulic pump driven by the engine;
A first hydraulic actuator connected to the first hydraulic pump via a control valve;
Power storage means for storing electrical energy;
An operation of converting mechanical energy received from the engine into electric energy and supplying the electric energy to the power storage unit, and an operation of converting electric energy received from the power storage unit into mechanical energy and supplying the energy to the first hydraulic pump. Energy conversion means that can be selectively performed;
The consists both energy conversion means and the storage means so as supplied with electrical energy, and a drive source of the operation unit is supplied with electrical energy from at least one of said energy conversion means and said storage means And a first electric motor. 2. The hydraulic drive device according to claim 1, wherein electric energy generated by regenerative control of the first electric motor is stored in the power storage means. 3. The apparatus according to claim 1, further comprising: a second hydraulic pump driven by the first electric motor; and a second hydraulic actuator driven by the second hydraulic pump. Hydraulic drive device. The hydraulic drive apparatus according to claim 3, wherein the first electric motor, the second hydraulic pump, and the second hydraulic actuator are integrally formed. A second electric motor that receives supply of electric energy from at least one of the energy conversion means and the power storage means;
A third hydraulic pump driven by the second electric motor,
5. The hydraulic drive device according to claim 3, wherein pressure oil from the third hydraulic pump is supplied between the first hydraulic pump and the control valve. 6.

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