JP4705927B2 - Hybrid construction machine - Google Patents

Description

  The present invention relates to a hybrid construction machine such as a hybrid hydraulic excavator including an engine, a hydraulic pump, an electric motor, and a power storage device as a power unit.

  In general, the work load of a construction machine is likely to change greatly, and the working time is not constant. For this reason, it is difficult to ensure good engine efficiency. For this reason, conventionally, as shown in Patent Document 1 and Patent Document 2, a hybrid construction machine has been proposed in which an engine and a power storage device, that is, a battery are used in parallel to average the engine load. Yes.

The prior art disclosed in Patent Document 1 has a configuration in which the rotating shaft of the engine is connected to both the rotating shaft of the electric motor and the rotating shaft of the hydraulic pump, and the engine drives these electric motor and hydraulic pump at the same time. When the load is light, the generator is rotated by the power of the engine, and the engine power is stored in the power storage device as electric power. When the load is heavy, power is drawn from the power storage device to support driving of the engine. ing. In the prior art disclosed in Patent Document 2, an engine and a generator are connected, and all of the engine power is supplied to the generator to generate electric power. The electric motor is rotated by the electric power, and the hydraulic pump is further driven by the electric motor. It is configured to turn. When the pump load is light or no load, electric power is stored in the battery, and when the pump load is heavy, the electric power is drawn from the battery. In the prior art described above, the load is averaged in this way, and the efficiency of the engine is improved.
JP 2001-16704 A JP 2000-283107 A

  By the way, in the prior art shown by patent document 1 among the prior art mentioned above, since an engine, a generator, and a hydraulic pump are connected to the same rotating shaft, an engine, a generator, and a hydraulic pump are always together. Driven. As a result, there is an advantage that the power, distribution, and support of each other can be distributed among the engine, generator, and hydraulic pump. However, for example, when the hydraulic operation is not performed, the existence of the hydraulic pump is obstructive, and the engine only needs to drive the electric motor. However, the hydraulic pump is also driven, and unnecessary dragging of the pump occurs. Further, as one effective means for improving the fuel consumption of the engine, it is conceivable to stop the engine when no operation is performed. However, in this prior art, when the operator stops the engine and moves the operation lever to restart the engine and operate the actuator, the moment of inertia of the engine is large. A considerable response time is required, and the operability of the hybrid construction machine is lowered. That is, this prior art also has a problem that the advantages of a motor with a fast startup speed cannot be fully exhibited.

  In the prior art shown in Patent Document 2, the engine, the generator, and the hydraulic pump are not connected by the same rotating shaft. Therefore, as in the prior art shown in Patent Document 1, the engine, the generator, There is a problem that it is difficult to effectively utilize the power of these three parties in a state where the three of the hydraulic pumps can be driven.

  The present invention has been made from the actual situation in the above-described prior art. The purpose of the present invention is to enable the power of these three parties to be mutually effective when the engine, generator, and hydraulic pump can be driven. Providing a hybrid construction machine that can be used when the engine, generator, or hydraulic pump is unnecessary for driving the other two parties. There is to do.

In order to achieve this object, the present invention relates to an engine having a rotating shaft, a hydraulic pump having a rotating shaft, an electric motor having a rotating shaft and also serving as a generator, and electric power generated by driving the electric motor. The power unit includes a power storage device capable of storing and capable of supplying electric power for driving the electric motor, an electric actuator and a hydraulic actuator driven by the power unit, and an operation mechanism for operating these actuators. selected in a hybrid construction machine, the rotation axis of the engine, a rotation shaft of the hydraulic pump, only set independently of each other the three axes of rotation of the electric motor, the power transmission between said three rotational axes comprising a feasible power distribution unit, said power distribution means comprises a planetary gear mechanism, each of the three axes of rotation, said Yu The outer ring gear included in the gear mechanism, the planet carrier included in the planetary gear mechanism, and the sun gear included in the planetary gear mechanism are connected to the corresponding ones, and the three rotation shafts are individually brought into a rotation stopped state. A stop holding means capable of holding, and controlling the engine to stop when the operating mechanism is in a non-operating state and the power storage device stores a larger amount of power, and the operating mechanism resumes operation And a controller that controls the engine to restart when the hydraulic pump is driven by the electric motor when the electric power stored in the power storage device is smaller than a predetermined amount .

  In the present invention configured as described above, when the power distribution means enables the power transmission between the three rotating shafts of the engine, the electric motor that also serves as the generator, and the hydraulic pump, the three members are driven. In addition, the powers of these three parties can be used effectively. Further, for example, in a state where the electric motor is stopped, only the hydraulic pump can be driven by the engine via the power distribution means. Further, when there is no load on the hydraulic system, the hydraulic pump is stopped, and only the electric motor can be driven by the engine to generate electric power. Thereby, the drag loss of the pump can be eliminated. Further, when the hydraulic pump is activated by the electric motor, only the hydraulic pump can be driven by the electric motor in a state where the engine is stopped by the power distribution means. As a result, the hydraulic pump can be started at high speed by the electric motor, excluding the influence of the inertia and friction of the engine.

  Further, for example, the hydraulic pump can be driven by combining the power of the engine and the power of the electric motor via the power distribution means. Further, for example, the power of the engine can be utilized as the drive of the hydraulic pump and transmitted as the drive of the electric motor via the power distribution means, and the generated electric power can be accumulated in the power storage device.

  As described above, the present invention can realize the distribution and support of each other's power among the three parties when the engine, the electric motor, and the hydraulic pump can be driven by the power distribution means. When any one of the engine, the generator, and the hydraulic pump is unnecessary for driving the other two, the unnecessary one can be stopped. Therefore, the power of the engine can be utilized to the maximum and the high-speed response performance of the electric motor can be fully utilized. Thereby, workability | operativity can be improved and energy consumption can be reduced simultaneously.

In addition, the present invention is capable of accumulating electric power generated by driving an engine having a rotating shaft, a hydraulic pump having a rotating shaft, an electric motor having a rotating shaft and also serving as a generator, In a hybrid construction machine having a power unit including a power storage device capable of supplying electric power for driving the electric motor, an electric actuator and a hydraulic actuator driven by the power unit, and an operation mechanism for operating these actuators.
A power distribution capable of selectively performing power transmission between the three rotation shafts by independently providing three rotation shafts of the engine rotation shaft, the hydraulic pump rotation shaft, and the electric motor rotation shaft. And the power distribution means comprises a planetary gear mechanism, and each of the three rotating shafts is connected to an outer ring gear included in the planetary gear mechanism, a planet carrier included in the planetary gear mechanism, and the planetary gear mechanism. A stop holding means that can be connected to any one of the included sun gears and that can hold the three rotary shafts individually in a rotation stop state, and the target displacement of the hydraulic pump is determined by the engine torque and the pump required pressure. The pump rotation speed is determined from the determined target displacement volume and the pump required flow rate, and the engine rotation speed and the pump rotation speed determined above are used to determine the pump rotation speed. It is characterized by comprising a controller for performing operation for obtaining a target rotational speed of the motive.

In addition, the present invention is capable of accumulating electric power generated by driving an engine having a rotating shaft, a hydraulic pump having a rotating shaft, an electric motor having a rotating shaft and also serving as a generator, In a hybrid construction machine having a power unit including a power storage device capable of supplying electric power for driving the electric motor, an electric actuator and a hydraulic actuator driven by the power unit, and an operation mechanism for operating these actuators. A power distribution capable of selectively performing power transmission between the three rotation shafts by independently providing three rotation shafts of the engine rotation shaft, the hydraulic pump rotation shaft, and the electric motor rotation shaft. And the power distribution means comprises a planetary gear mechanism, and each of the three rotation shafts is included in the planetary gear mechanism. Stop holding that can be connected to any one of a ring gear, a planet carrier included in the planetary gear mechanism, and a sun gear included in the planetary gear mechanism, and can individually hold the three rotation shafts in a rotation stop state. Means for controlling the engine to stop when the operating mechanism is in a non-operating state and electric power greater than a predetermined amount is stored in the power storage device. The hydraulic pump is driven by an electric motor, and when the electric power stored in the power storage device is smaller than a predetermined amount, the engine is restarted, and the target displacement of the hydraulic pump is determined by the engine torque, the pump required pressure, From the obtained target displacement volume and the required pump flow rate, and determine the pump rotation speed. And a fit was pump rotational speed is characterized by comprising a controller for performing operation for obtaining a target rotational speed of the electric motor.

  The present invention provides three rotary shafts, that is, a rotary shaft of an engine, a rotary shaft of a hydraulic pump, and a rotary shaft of an electric motor, independently of each other, and power that can selectively implement power transmission between the three rotary shafts. Since the power distribution means is provided, the power of these three parties can be driven in the state where the engine, the electric motor also serving as a generator, and the hydraulic pump can be driven via the power distribution means. In addition to being able to make effective use of each other, if any of the engine, electric motor, or hydraulic pump is not necessary for the driving of the other two, the unnecessary ones can be stopped, and between the two axes The power transmission loss can be reduced, and the high-speed response of the electric motor can be utilized. As a result, the fuel efficiency can be improved as compared with the prior art, and excellent workability can be ensured.

  The best mode for carrying out the hybrid construction machine according to the present invention will be described below with reference to the drawings.

[Configuration of First Embodiment]
FIG. 1 is a circuit diagram showing a main part of a hybrid hydraulic excavator which is a first embodiment of a hybrid construction machine according to the present invention.

  The first embodiment is, for example, a hybrid hydraulic excavator. As shown in FIG. 1, the engine 1 has a rotating shaft 1a, the hydraulic pump 14 has a rotating shaft 14a, and the rotating shaft 13a. And a power unit including a battery 11 that can store electric power generated by driving the electric motor 13 and can supply electric power for driving the electric motor 13. In addition, an electric actuator driven by the power unit, for example, an electric motor 9 also serving as a generator for driving the revolving body 8, a hydraulic actuator, for example, hydraulic cylinders 6 and 7 such as a boom cylinder and an arm cylinder, and these actuators An operation mechanism including an operation lever 10a to be operated and operation levers 5a and 5b is provided.

  In particular, as shown in FIG. 1, in the first embodiment, the rotating shaft 1a of the engine 1, the rotating shaft 14a of the hydraulic pump 14, and the rotating shaft 13a of the electric motor 13 are provided independently of each other. Stop holding means, for example, braking devices 20, 18 and 15, capable of individually holding the three rotary shafts in a rotation stop state are provided. Further, power distribution means, for example, a planetary gear mechanism, capable of selectively performing power transmission between the three rotary shafts 1a, 14a, 13a is provided. Each of the three rotary shafts 1a, 14a, 13a described above is connected to any one of the outer ring gear 3, the planet carrier 19, and the sun gear 2 included in the planetary gear mechanism.

  For example, the rotating shaft 1a of the engine 1 is connected to the outer ring gear 3 of the planetary gear mechanism, the rotating shaft 13a of the electric motor 13 is connected to the sun gear 2 of the planetary gear mechanism, and the rotating shaft 14a of the hydraulic pump 14 is Are connected to the planet carrier 19 through gears 16 and 17. The braking device 20 described above is arranged so that the rotation shaft 1a of the engine 1 can be stopped via the outer ring gear 3, and the braking device 18 is connected to the hydraulic pump 14 via the planetary carrier 19 and the gears 17, 16. The rotating shaft 14a is arranged so as to be able to stop rotating, and the braking device 15 is arranged so that the rotating shaft 13a of the electric motor 13 can be stopped.

  The pressure oil discharged from the hydraulic pump 14 is supplied to the hydraulic cylinders 6 and 7 through the control valve 5. The opening amount of the control valve 5 is controlled according to the operation signals y5a and y5b of the operation levers 5a and 5b described above, and the operation speed of the hydraulic cylinders 6 and 7 is controlled.

  When the rotating shaft 13a of the electric motor 13 is rotated via the sun gear 2 of the planetary gear mechanism, the electric motor 13 functions as a generator and is stored in the battery 11 by the control of the converter / inverter 12, or Power is supplied to the inverter 10 to drive the electric motor 9 for the revolving structure 8. Conversely, when the electric motor 13 is requested for power from the planetary gear mechanism, it absorbs electric power from the battery 11 and functions as a motor to rotate the rotating shaft 13a.

  In addition, when the operation signal y10a of the operation lever 10a is given to the converter / inverter 10, the rotational speed of the electric motor 9 is controlled and the revolving structure 8 is driven.

  The signal of the engine speed sensor 101, the signal of the pump speed sensor 102, the signal of the motor speed sensor 104, the signal of the displacement measuring sensor 103 that measures the displacement volume that determines the discharge amount of the hydraulic pump 14, the discharge of the hydraulic pump 14 Signal of pressure sensor 111 for detecting pressure, current signal 105 and voltage signal 106 of converter / inverter 12 for controlling electric motor 13, voltage signal 107 of battery 11, current signal 108 and voltage signal 109 of converter / inverter 10, control lever Operation signals such as 5a, 5b, and 10a are transmitted to the controller 4.

  For example, the controller 4 performs control to stop the engine 1 when the operation levers 5a, 5b, 10a, etc. included in the operation mechanism are all in a non-operating state and the battery 11 stores a power larger than a predetermined amount Vhi. When the operation levers 5a, 5b, 10a, etc. included in the operation mechanism are resumed, the hydraulic pump 14 is driven by the electric motor 13, and the engine 1 is restarted when the electric power stored in the battery 11 is smaller than the predetermined amount Vlow. It includes processing means for performing control to be activated.

  The controller 4 obtains the target displacement volume qdisp of the hydraulic pump 14, for example, from the engine torque Tp and the pump required pressure ps, obtains the pump rotation speed Np from the obtained target displacement volume qdisp and the pump requested flow rate Qs, Processing means for calculating the target rotational speed Ng of the electric motor 13 from the engine rotational speed Ne and the pump rotational speed Np determined above is also included.

[Operation of First Embodiment]
(A) In the first embodiment configured as described above, when the operation levers 5a and 5b are not operated, the rotating shaft 14a of the hydraulic pump 14 is operated by the brake device 18 via the planetary carrier 19 and the gears 17 and 16. Is stopped and held, and the output of the engine 1 can be applied to the electric motor 13 and used for power generation. Thereby, the drag loss of the hydraulic pump 14 can be prevented from occurring. In this case, the power of the engine 1 is given to the outer ring gear 3 of the planetary gear mechanism via the rotating shaft 1a, and further given to the rotating shaft 13a via the sun gear 2, and the electric motor 13 is driven. The rotational speed Ng of the electric motor 13 at this time is
Ng = (Go / Gs) x Ne (1)
It becomes. Here, Ng: rotational speed of the electric motor 13, Ne: rotational speed of the engine 1, Go: number of teeth of the outer ring gear 3, and Gs: number of teeth of the sun gear 2 are shown.

  In the planetary gear mechanism, since the number of teeth of the outer ring gear 3 is larger than the number of teeth of the sun gear 2, the rotational speed Ng of the electric motor 13 according to the equation (1) is larger than the rotational speed Ne of the engine 1. The electric motor 13 is more efficient at high rotational speeds, and no transmission is required between the engine 1 and the electric motor 13.

(B) In the first embodiment, the rotating shaft 1a of the engine 1 is stopped by the braking device 20 via the outer ring gear 3 of the planetary gear mechanism, and the hydraulic pump 14 is started by the electric motor 13. Can be made. The rotational speed Np of the hydraulic pump 14 at this time is
Np = {Gs / (Go + Gs)} × (G17 / G16) × Ng (2)
It becomes. With this function, the first embodiment can stop the engine 1 without hindering the operator even during the suspension period of work of the hybrid hydraulic excavator, and can reduce fuel consumption.

  In the first embodiment, when the re-operation is performed after the engine 1 is stopped, the hydraulic pump 14 can be started by the electric motor 13 as described above. The operation can be started smoothly without making the user notice the stop of the engine 1.

  FIG. 2 is a flowchart showing a first example of a processing procedure executed by a controller or the like provided in the circuit shown in FIG. FIG. 2 shows a procedure from stop to restart of the engine 1.

  When the engine 1 is started as shown in the procedure s1, it is determined whether or not an operation signal is input from the operation levers 5a, 5b, and 10a as shown in the procedure s2. If this determination is yes, the engine 1 is driven as it is, and if no, the process proceeds to step s3. In step s3, it is determined whether the voltage of the battery 11 is greater than a predetermined amount Vhi. If this determination is no, the operation of the engine 1 is continued, and electric power is generated by the electric motor 13 to be stored in the battery 11. If the above determination is yes, the process proceeds to step s4. In this procedure s4, control for stopping the engine 1, the electric motor 13, and the hydraulic pump 14 is performed. This pauses the work.

  Next, the procedure proceeds to step s5, and it is determined whether or not an operation signal is input from the operation levers 5a, 5b, and 10a, that is, whether or not the operation is resumed. If this determination is NO, the procedure moves to step s6. In step s6, it is determined whether the voltage of the battery 11 is smaller than a predetermined amount Vlow. If yes, the procedure returns to step s1, the engine 1 is started, and the battery 11 is charged by the electric power generated by the electric motor 13. If the determination in step s6 is no, the process returns to step s5, and the confirmation of the voltage of the battery 11 is repeated. If the determination in step s5 described above is yes, the operation is resumed, and the procedure moves to step s7, where the hydraulic pump 14 is activated by the electric motor 13.

  Next, proceeding to step s8, it is determined whether or not the voltage of the battery 11 is smaller than a predetermined amount Vlow. If this determination is YES, the process returns to step s1 and the engine 1 is started. If this determination is NO, the process moves to step s9, and it is determined whether or not an operation signal is input from the operation levers 5a, 5b, and 10a. If this determination is yes, the process returns to step s8, and the confirmation of the voltage of the battery 11 is repeated. If the determination in step s9 is no, stop control of the electric motor 13 and the hydraulic pump 14 is performed.

  Thus, in the first embodiment, the engine 1 can be stopped even in a short work stop period without adversely affecting the work efficiency.

(C) Moreover, in this 1st Embodiment, the drive of the engine 1 can be supported by the electric motor 13, and the engine 1 can be made into a comparatively small shape, and the engine 1 is in an optimal fuel efficiency state. Can be driven by.

  In general, it is said that combustion efficiency is good when the engine 1 is driven in a state where a constant rotational speed and torque are maintained. However, in the case of a construction machine such as the hybrid hydraulic excavator, since the load is constantly fluctuating, the engine 1 cannot be driven in the same state. In the first embodiment, it is possible to drive the engine 1 with a constant load by performing speed control of the electric motor 13.

In the state in which the driving of the engine 1, the electric motor 13, and the hydraulic pump 14 is enabled, the relationship between the rotational speed and torque of the engine 1, the hydraulic pump 14, and the electric motor 13 is expressed by the following equation. Given in. That is,
Ng = {(1 + α) / α} × (G16 / G17) × Np− (1 / α) × Ne (3)
Np = [{α / (1 + α)} × Ng + {1 / (1 + α)} × Ne] × (G17 / G16) (4)
Where α = G2 / G3
Tg = {α / (1 + α)} × (G16 / G17) × Tp (5)
Te = {1 / (1 + α)} × (G16 / G17) × Tp (6)
Here, Np: rotational speed of hydraulic pump 14, Ne: rotational speed of engine 1, G17: number of teeth of gear 17, G16: number of teeth of gear 16, G2: number of teeth of sun gear 2, G3: outer ring gear 3 , Tg: torque of the electric motor 13, Te: torque of the engine 1, and Tp: torque of the hydraulic pump 14.

FIG. 3 is a flowchart showing a second example of a processing procedure executed by a controller or the like provided in the circuit shown in FIG. As shown in step s20, in a state where the engine 1 is driven while maintaining the optimum rotational speed Neop and torque Teop, as shown in step s21, a signal y5a corresponding to the operation amount of the operation levers 5a, 5b, 10a. , Y5b, y10a are detected, as shown in step s22, the rotational speed Ns of the swing body 8 is calculated according to the signal y10a, and the converter / inverter 10 is commanded so that the motor 9 has the rotational speed Ns. Is output. At the same time, as shown in step s23, the required flow rate Qs of the hydraulic pump 14 is calculated according to the signals y5a and y5b. Further, as shown in step s24, a signal qdispo from the displacement volume measuring sensor 103 is input. Next, as shown in step s25, the target rotational speed Npo of the hydraulic pump 14 is calculated from the required flow rate Qs of the hydraulic pump 14 and the displacement volume qdispo, and the rotational speed Ng of the electric motor 13 in the equation (3) and the engine 1 The target rotational speed Ngo of the electric motor 13 is calculated based on the relationship between the rotational speed Ne of the hydraulic pump 14 and the rotational speed Np of the hydraulic pump 14, and the value is output to the converter / inverter 12 as a command. Further, as shown in step s26, the pressure of the oil discharged from the hydraulic pump 14 is detected by the pressure sensor 111, and as shown in step s27, the power required for the load at that time, that is, the power Ep,
Ep = Qs × Ps (7)
Sought by.

As is clear from the above equation (6), the torque Te of the engine 1 and the torque Tp of the hydraulic pump 14 are in a proportional relationship, and the hydraulic pump 14 for making the torque Te of the engine 1 the optimum torque Teop. Torque Tp is
Tp = (1 + α) × (G17 / G16) × Teop (8)
(Procedure s28).

Next, as shown in step s29, the relationship between the pressure Ps of the hydraulic oil discharged from the hydraulic pump 14, the torque Tp of the hydraulic pump 14, and the displacement volume qdisp.
Ps = Tp / qdisp (9)
Therefore, the target displacement volume qdisp is obtained, and the hydraulic pump 14 is controlled so as to be the target displacement volume qdisp.

Next, as shown in step s30, the relationship between the target displacement volume qdisp of the hydraulic pump 14, the required flow rate Qs of the hydraulic pump 14, and the rotational speed Np of the hydraulic pump 14 is shown.
Np = Qs / qdisp (10)
Thus, the rotational speed Np of the hydraulic pump 14 is obtained, and the rotational speed Ng of the electric motor 13 is obtained from the rotational speed Np and the equation (3), and a signal corresponding to this value is output to the converter / inverter 12. The By such arithmetic processing, both driving of the engine 1 in the optimum fuel consumption state and provision of necessary power of the hydraulic pump 14 can be satisfied simultaneously.

  When the rotational speed Ng of the electric motor 13 is 0 or when the rotating shaft 13a of the electric motor 13 is stopped by the braking device 15, all of the power of the engine 1 is utilized for driving the hydraulic pump 14. be able to.

  FIG. 4 is a diagram showing the characteristics obtained in the first embodiment. According to the operations and functions described in (A) to (C) described above, the first embodiment can ensure the characteristics of the engine 1 shown in FIG.

  FIG. 4A shows the characteristics over time when the operation levers 5a, 5b, and 10a are selectively operated to the maximum operation amount. It is shown that irregular characteristics occur intermittently depending on the work.

  As the operation levers 5a, 5b, and 10a are operated, the load changes as shown by the broken line in FIG. In the conventional construction machine, since it is impossible to predict when the construction machine starts and stops in such a situation, it is necessary to continuously operate the engine 1. A thin line B in FIG. 4B shows the conventional engine power.

  On the other hand, in the first embodiment, the engine 1 can be driven on and off as indicated by the thick line A in FIG. The state where the engine 1 is being driven in an optimal state is the ON state, and the state where the engine 1 is stopped is the OFF state. When the engine power is larger than the load power in the ON state, the excess energy can be stored in the battery 11 as shown at t1-t2 or t3-t4 in FIG. When the engine power is smaller than the load power, energy can be extracted from the battery 11 as indicated by t0-t1 in FIG. In order to make the one OFF time of the engine 1 as long as possible, even if the operation with the operation levers 5a, 5b, and 10a is finished, the engine 1 is kept for a while as shown at t1-t2 in FIG. The battery 11 is charged without stopping. Thereby, even if some operations are performed when the engine 1 is OFF, the necessary power can be supplied only by the battery 11, and the engine 1 does not have to be started during that time.

(D) In the first embodiment, even when the engine 1 is driven at a constant rotational speed, the rotational speed Np of the hydraulic pump 14 and the flow rate discharged from the hydraulic pump 14 are controlled by the speed control of the electric motor 13. Can be adjusted.

The flow rate Qs of the hydraulic pump 14 is
Qs = Np × qdisp
(As mentioned above, qdisp is the displacement volume of the hydraulic pump 14)
In general, the variable range of the displacement volume qdisp is limited by the structure. For this reason, it has been difficult to change the flow rate Qs discharged from the hydraulic pump 14 quickly and significantly.

On the other hand, in the first embodiment, the rotational speed Np of the hydraulic pump 14 is the above-described equation (4), that is,
Np = [{α / (1 + α)} × Ng + {1 / (1 + α)} × Ne] × (G17 / G16)
As is apparent from the above, since it is determined by the rotational speed Ne of the engine 1 and the rotational speed Ng of the electric motor 13, it is possible to control the rotational speed Ng of the electric motor 13 without changing the rotational speed Ne of the engine 1. The rotational speed Np of the hydraulic pump 14 can be changed. In addition, since the response speed of the electric motor 13 is fast, it is possible to respond quickly to load demands and to quickly change the flow rate Qs discharged from the hydraulic pump 14.

(E) Moreover, in this 1st Embodiment, the change from the drive of the hydraulic pump 14 by the electric motor 13 to the drive of the hydraulic pump 14 by the engine 1 can be performed smoothly. That is, as shown in the above equation (4), the rotational speed Np of the hydraulic pump 14 is a function of the rotational speed Ne of the engine 1 and the rotational speed Ng of the electric motor 13. Therefore, when the engine 1 is started from the state where the hydraulic pump 14 is driven by the electric motor 13 and the hydraulic pump 14 is driven by the engine 1, the rotational speed Ng of the electric motor 13 is set to the rotation of the engine 1. By controlling so as to decrease in accordance with the increase in the speed Ne, the flow rate Qs discharged from the hydraulic pump 14 can be controlled so as not to change without substantially changing the rotational speed Np of the hydraulic pump 14. That is, the performance of the hybrid hydraulic excavator can be kept good without being affected by changes in the power source.

[Effect of the first embodiment]
According to the first embodiment configured as described above, the engine 1, the electric motor 13, and the hydraulic pressure are released by releasing the rotation stop holding of the rotating shafts 13a, 14a, 1a by the braking devices 15, 18, 20 respectively. In a state where the three of the pumps 14 can be driven, the powers of these three parties can be effectively utilized. In addition, the hydraulic pump 14 can be driven by the engine 1 via the planetary gear mechanism in a state where the rotation shaft 13a of the electric motor 13 is stopped and held by the braking device 15. Further, in a state where the rotating shaft 14 a of the hydraulic pump 14 is stopped and held by the braking device 18, the electric motor 13 is driven by the engine 1 through the planetary gear mechanism, and the electric power generated by the electric motor 13 is supplied to the battery 11. Can be accumulated. Further, in a state where the rotation shaft 1 a of the engine 1 is stopped and held by the braking device 20, the electric motor 13 is driven by the electric power from the battery 11 through the planetary gear mechanism, and the hydraulic pump 14 is driven by the electric motor 13. be able to.

  For example, the hydraulic pump 14 can be driven by combining the power of the engine 1, that is, the engine power and the power of the electric motor 13 through a planetary gear mechanism. Further, for example, the power of the engine 1 can be utilized as the drive of the hydraulic pump 14 via the planetary gear mechanism, and can be transmitted as the drive of the electric motor 13, and the generated electric power can be stored in the battery 11.

  As described above, in the first embodiment, in a state where the three of the engine 1, the electric motor 13, and the hydraulic pump 14 can be driven, the power of each of the three can be effectively utilized. At the same time, when any of the engine 1, the electric motor 13, and the hydraulic pump 14 is unnecessary for driving the other two, the unnecessary one can be stopped, and the power transmission loss between the two shafts can be reduced. Can be reduced. Further, the quick response of the electric motor 13 can be utilized, and the engine 1 can be stopped in small increments without deteriorating the operability of the hybrid hydraulic excavator. As a result, fuel efficiency can be improved and excellent operability can be ensured.

  Further, by using the power storage function of the battery 11, it is possible to achieve load concentration and equalization of the engine 1 as shown by the thick line A in FIG. It can be driven and can be stopped immediately when it is not necessary to drive it. As a result, the total drive time of the engine 1 can be reduced, and fuel consumption can be improved.

  In addition, the range of the flow rate Qs discharged from the hydraulic pump 14 can be expanded by the wide range of speed adjustment characteristics of the electric motor 13, and accordingly, the adjustment range of the working speed in the hybrid hydraulic excavator is expanded. Can improve the function. Further, the engine 1 can be supported by the power of the electric motor 13, and a load exceeding the maximum power of the engine 1 can be dealt with.

  Further, since the power distribution function is realized by the planetary gear mechanism and the mechanical power transmission mechanism such as the braking devices 20, 18, 15 and the like, high efficiency can be secured and a stable structure can be realized. In addition, most of the power of the engine 1 can be utilized for driving the hydraulic pump 14, and a relatively small amount of power can be stored as electric energy via the motor 13, thus realizing efficient energy distribution. Can be made.

  FIG. 5 is a hydraulic circuit diagram showing another example of the stop holding means that can hold the rotary shaft of the hydraulic pump in the rotation stop state. In the first embodiment described above, the braking device 18 that stops the planetary carrier 19 of the planetary gear mechanism to which the rotary shaft 14a is connected is provided as a stop-holding means capable of stopping and holding the rotary shaft 14a of the hydraulic pump 14. Although configured, stop holding means capable of stopping and holding the rotating shaft 14a of the hydraulic pump 14 can be configured by an on-off valve 302 as shown in FIG.

  As shown in FIG. 5, for example, when the operation lever 5a is not operated and the control valve 301 is returned to the neutral position, the discharge port of the hydraulic pump 14 is controlled by simultaneously closing the on-off valve 302. As a result, the hydraulic pump 14 cannot rotate, and a state equivalent to the braking device 18 in the first embodiment described above can be formed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram constituting a main part of a hybrid hydraulic excavator that is a first embodiment of a hybrid construction machine according to the present invention. 3 is a flowchart showing a first example of a processing procedure performed by a controller or the like provided in the circuit shown in FIG. 1. 6 is a flowchart illustrating a second example of a processing procedure performed by a controller or the like provided in the circuit illustrated in FIG. 1. It is a figure which shows the characteristic acquired by 1st Embodiment. Ru hydraulic circuit view showing another example of a holding can stop holding means rotation stop state the rotation axis of the hydraulic pump.

Explanation of symbols

1 Engine (Power unit)
1a Rotating shaft 2 Sun gear (power distribution means)
3 Outer ring gear (power distribution means)
4 Controller 5 Control valve 5a Operation lever (operation mechanism)
5b Operation lever (operation mechanism)
6 Hydraulic cylinder (hydraulic actuator)
7 Hydraulic cylinder (hydraulic actuator)
8 Revolving body 9 Electric motor (electric actuator)
10 Converter / Inverter 10a Operation lever (operation mechanism)
11 Battery (power storage device) [Power unit]
12 Converter / Inverter 13 Electric motor (Power unit)
13a Rotating shaft 14 Hydraulic pump (Power unit)
14a Rotating shaft 15 Breaking device (stop holding means)
16 gear (power distribution means)
17 Gear (Power distribution means)
18 Braking device (stop holding means)
19 Planetary carrier (power distribution means)
20 Braking device (stop holding means)
21 planetary gear (power distribution hand stage)
2 01 gear (power distribution hand stage)
2 04 Gear (Power distribution means)
301 Control valve 302 On-off valve (stop holding means)

Claims (3)

An engine having a rotating shaft, a hydraulic pump having a rotating shaft, an electric motor having a rotating shaft and also serving as a generator, and electric power generated by driving the electric motor can be stored, and electric power for driving the electric motor In a hybrid construction machine having a power unit including a power storage device capable of supplying power, an electric actuator and a hydraulic actuator driven by the power unit, and an operation mechanism for operating these actuators,
A rotating shaft of the engine, a rotation shaft of the hydraulic pump, set independently of each other the three axes of rotation of the electric motor,
Power distribution means capable of selectively performing power transmission between the three rotating shafts ;
The power distribution means comprises a planetary gear mechanism,
Each of the three rotating shafts is connected to an outer ring gear included in the planetary gear mechanism, a planet carrier included in the planetary gear mechanism, or a sun gear included in the planetary gear mechanism,
Stop holding means capable of individually holding the three rotation shafts in a rotation stop state,
Control is performed to stop the engine when the operating mechanism is in a non-operating state and electric power larger than a predetermined amount is stored in the power storage device. When the operating mechanism is restarted, the motor performs the hydraulic pressure control. A hybrid construction machine comprising a controller for driving a pump and restarting the engine when electric power stored in the power storage device is smaller than a predetermined amount . An engine having a rotating shaft, a hydraulic pump having a rotating shaft, an electric motor having a rotating shaft and also serving as a generator, and electric power generated by driving the electric motor can be stored, and electric power for driving the electric motor In a hybrid construction machine having a power unit including a power storage device capable of supplying power, an electric actuator and a hydraulic actuator driven by the power unit, and an operation mechanism for operating these actuators,
Three rotating shafts, the rotating shaft of the engine, the rotating shaft of the hydraulic pump, and the rotating shaft of the electric motor, are provided independently of each other,
Power distribution means capable of selectively performing power transmission between the three rotating shafts;
The power distribution means comprises a planetary gear mechanism,
Each of the three rotating shafts is connected to an outer ring gear included in the planetary gear mechanism, a planet carrier included in the planetary gear mechanism, or a sun gear included in the planetary gear mechanism,
Stop holding means capable of individually holding the three rotation shafts in a rotation stop state,
The target displacement volume of the hydraulic pump is determined from the engine torque and the required pump pressure, the pump rotation speed is determined from the determined target displacement volume and the required pump flow rate, and the above described pump rotation speed is calculated from the engine rotation speed and the determined pump rotation speed. A hybrid construction machine comprising a controller for calculating a target rotational speed of an electric motor . An engine having a rotating shaft, a hydraulic pump having a rotating shaft, an electric motor having a rotating shaft and also serving as a generator, and electric power generated by driving the electric motor can be stored, and electric power for driving the electric motor In a hybrid construction machine having a power unit including a power storage device capable of supplying power, an electric actuator and a hydraulic actuator driven by the power unit, and an operation mechanism for operating these actuators,
Three rotating shafts, the rotating shaft of the engine, the rotating shaft of the hydraulic pump, and the rotating shaft of the electric motor, are provided independently of each other,
Power distribution means capable of selectively performing power transmission between the three rotating shafts;
The power distribution means comprises a planetary gear mechanism,
Each of the three rotating shafts is connected to an outer ring gear included in the planetary gear mechanism, a planet carrier included in the planetary gear mechanism, or a sun gear included in the planetary gear mechanism,
Stop holding means capable of individually holding the three rotation shafts in a rotation stop state,
Control is performed to stop the engine when the operating mechanism is in a non-operating state and electric power larger than a predetermined amount is stored in the power storage device. When the operating mechanism is restarted, the motor performs the hydraulic pressure control. When the pump is driven and the electric power stored in the power storage device is smaller than a predetermined amount, the engine is restarted, and the target displacement of the hydraulic pump is obtained from the engine torque and the pump required pressure. And a controller for calculating a pump rotational speed from the obtained target displacement volume and a requested pump flow rate and calculating a target rotational speed of the electric motor from the engine rotational speed and the obtained pump rotational speed. Hybrid construction machine.

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