JP2010047125A - Traveling control circuit of hybrid construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably secure traveling straightness of a hybrid construction machine when traveling only by oil pressure driving. <P>SOLUTION: The hybrid construction machine includes: hydraulic motors 1L and 1R on both sides which operates traveling sections on both sides; hydraulic pumps 14L and 14R on both sides which supplies pressure oil to the hydraulic motors 1L and 1R for traveling; a motor generator 12 which performs regenerative power generation using surplus power of a rotary drive section such as a rotation mechanism; a battery 19 which charges power acquired by regenerative power generation; and a controller 30 which controls a drive section of an electrical system, and traveling drive is carried out by output of an engine 11 and/or output of the battery 19. The controller 30 includes: a pump output control section 38 which carries out variable control of the output of the hydraulic pumps 14L and 14R; a traveling drive determination section 39 which determines whether the traveling section is driven independently with an oil pressure load or not, and when traveling independently by the oil pressure load, the hydraulic pumps 14L and 14R are set so that the output may become larger than driving output of straight forward movement in second gear speed traveling on a flat ground. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a travel control circuit for a hybrid construction machine, and more particularly to a travel control circuit for a hybrid construction machine that enables load fluctuations to be leveled.

  Conventionally, a construction machine employs a hydraulic drive system in which an actuator is generally driven by discharge oil of a hydraulic pump driven by an engine. However, since the hydraulic drive system wastes a lot of hydraulic energy, in recent years, hybrid construction machines that use an electric motor drive system in addition to the hydraulic drive system as a drive source have been developed.

  This type of hybrid construction machine includes, for example, left and right hydraulic actuators (hydraulic cylinders, hydraulic motors, etc.) that operate left and right hydraulic drive units such as a traveling unit, a turning unit, a boom, an arm, and a bucket, and a direction switch to the hydraulic actuator. Left and right hydraulic pumps that supply pressure oil via a valve, a motor generator that performs regenerative power generation using surplus power such as a hydraulic drive unit for a swivel unit, a power storage device that charges the regenerated power, and And a controller that comprehensively controls each drive unit of an electric system such as a motor generator and is configured to be able to run by driving the hydraulic pump by the output of the engine and / or the output of the power storage device. ing.

According to the hybrid construction machine, by driving an electric load in addition to a hydraulic load, load fluctuations can be leveled and energy can be saved by energy regeneration.
JP 2001-207482 A

  In the prior art described in Patent Document 1, depending on the fluctuation state of the load operation, the sum of the output of the hydraulic load (horsepower) and the output of the electric load is the output of the engine alone or the output of the engine and the output of the power storage device. In this case, it is necessary to limit the output of the hydraulic load.

  Thus, when the hybrid construction machine is traveling alone by hydraulic drive, if the output of the hydraulic load by the left and right hydraulic pumps is limited, the maximum amount of hydraulic fluid can be supplied to the left and right traveling hydraulic motors. As a result, it becomes difficult to ensure the straight traveling performance of the hybrid construction machine.

  In other words, when the outputs of the left and right hydraulic pumps are limited during straight traveling by only hydraulic drive, the maximum flow rate of hydraulic oil cannot be discharged from the left and right hydraulic pumps as the pump output decreases. For this reason, the flow rate difference between the left and right hydraulic pumps increases, so that the flow rate difference between the hydraulic oil supplied to the left and right traveling hydraulic motors also increases, making it impossible to drive the hybrid construction machine straight ahead.

  Therefore, there is a technical problem to be solved in order to stably ensure the straight traveling performance of the hybrid construction machine when traveling only by hydraulic drive, and the present invention aims to solve this problem. And

  The present invention has been proposed in order to achieve the above object, and the invention according to claim 1 is characterized in that the left and right traveling hydraulic motors that drive the left and right traveling units, and the pressure oil is supplied to the traveling hydraulic motor. Left and right hydraulic pumps, a motor generator that performs regenerative power generation using surplus power of the hydraulic drive unit, a power storage device that charges the regenerated power, and each drive unit of the electric system such as the motor generator In a travel control circuit of a hybrid construction machine, which is provided with a controller for overall control and configured to be able to travel by driving the hydraulic pump by the output of the engine and / or the output of the power storage device, the engine output is traveled on a flat ground Provided is a travel control circuit for a hybrid construction machine, wherein the travel control circuit is set to be larger than a 2-speed linear drive output.

  According to this configuration, since the engine output is set to be larger than the flat ground traveling second speed linear drive output, it is possible to supply the required amount of hydraulic oil to the left and right traveling hydraulic motors.

The invention according to claim 2 uses the left and right traveling hydraulic motors that drive the left and right traveling units, the left and right hydraulic pumps that supply pressure oil to the traveling hydraulic motors, and the regeneration using the surplus power of the hydraulic drive unit. A motor generator for generating power, a power storage device for charging the regenerated power, and a controller for comprehensively controlling each drive unit of the electric system such as the motor generator, and the output of the engine and / or In a travel control circuit of a hybrid construction machine configured to be able to travel by driving the hydraulic pump by an output of a power storage device, the controller includes a pump output control unit that variably controls the output of the hydraulic pump, and the travel unit And a travel drive determination unit that determines whether or not the vehicle is driven solely by a hydraulic load, and when the travel unit is driven solely by a hydraulic load, the output of the hydraulic pump Providing travel control circuit for a hybrid construction machine and setting to be larger than the flat road surface 2 speed straight drive output.

  According to this configuration, when the traveling unit is driven solely by a hydraulic load, the outputs of the left and right hydraulic pumps are larger than the flat ground traveling 2-speed linear drive output. Oil is discharged. Therefore, there is no fear of causing a flow rate difference between the left and right hydraulic pumps, and it is possible to reliably prevent a flow rate difference from occurring in the hydraulic oil supplied to the left and right traveling hydraulic motors.

  According to the first aspect of the present invention, it is possible to supply hydraulic oil at a required flow rate to the left and right traveling hydraulic motors, so that the traveling straightness of the hybrid construction machine is ensured without restricting the output of the hydraulic load by the hydraulic pump. can do.

  According to the second aspect of the present invention, when the traveling unit is driven solely by a hydraulic load, there is no possibility of causing a flow rate difference between the hydraulic oils of the left and right traveling hydraulic motors. It can be ensured stably at all times, so that it can be driven for a long time even with only the engine output.

  The present invention provides a left and right traveling hydraulic motor for driving left and right traveling units in order to achieve the object of stably ensuring the straight traveling performance of a hybrid construction machine even during traveling by only hydraulic drive. A left and right hydraulic pump that supplies pressure oil to the traveling hydraulic motor, a motor generator that performs regenerative power generation using surplus power of a hydraulic drive unit (rotary drive unit such as a turning mechanism), and the regenerative power generation A power storage device that charges electric power, and a controller that comprehensively controls each drive unit of the electric system such as the motor generator, and the hydraulic pump is driven by the output of the engine and / or the output of the power storage device. In a travel control circuit of a hybrid construction machine configured to be able to travel, the controller includes a pump output control unit that variably controls the output of the hydraulic pump, and the travel unit is hydraulically negative. And a travel drive determination unit that determines whether or not the vehicle is driven independently, and when the travel unit is driven solely by a hydraulic load, the output of the hydraulic pump is higher than the level 2 travel straight drive output Realized by setting to be larger.

  A preferred embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a side view showing a hybrid construction machine according to the present embodiment. As shown in the figure, an upper swing body 3 is mounted on a lower traveling body 1 via a swing mechanism 2, and a boom 4, an arm 5 and a bucket 6 are driven on the upper swing body 3. A hydraulic actuator, that is, a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9 and a cabin 10 are mounted.

FIG. 2 is a block diagram showing a travel control circuit of the hybrid construction machine. In the figure, 11 is an engine as a mechanical drive unit, 12 is a motor generator as an electric assist drive unit, and the engine 11 and the motor generator 12 are connected to two input shafts of a variable speed reducer 13, respectively. Has been.

  Left and right hydraulic pumps (variable displacement main pumps) 14L, 14R and a pilot pump 15 are connected to the output shaft of the transmission 13, and the hydraulic pumps 14L, 14R are connected to high pressure hydraulic lines 16L, 16R. The control valve 17 is connected. The control valve 17 is provided with a plurality of directional control valves (not shown) for a hydraulic actuator, and each directional control valve has a traveling hydraulic motor (right side) 1L and a traveling hydraulic motor (left side). 1R, boom cylinder 7, arm cylinder 8 and bucket cylinder 9 are connected to each other.

  A battery (power storage device) 19 is connected to the motor generator 12 via an inverter 18, and a turning motor 21 is connected to the battery 19 via an inverter 20, and the turning motor 21 is turned as described above. The mechanism 2 is driven. Further, a resolver 22 that detects a rotational position and a rotational angle of the rotating shaft 21A, a mechanical brake 23 that applies a braking force to the rotating shaft 21A, and a rotating speed reducer 24 are connected to the rotating shaft 21A of the rotating motor 21. Then, the rotation angle and the rotation direction of the turning mechanism 2 are controlled based on the detection value by the resolver 22.

  Further, an operating device 26 is connected to the pilot pump 15 via a pilot line 25, and a control valve 17 and a pressure sensor 29 are connected to the operating device 26 via a hydraulic line 27 and a hydraulic line 28, respectively. Yes.

  Furthermore, a controller 30 that comprehensively controls each drive unit of the electric system is connected to the pressure sensor 29, and an electric signal corresponding to the hydraulic pressure in the hydraulic line 28 is transmitted from the pressure sensor 29 to the controller 30. . The controller 30 includes an arithmetic processing unit including a CPU and an internal memory, and includes a speed command conversion unit 31, a drive control device 32, and a turning drive control device 40.

  Next, each part of the component will be described in detail. The motor generator 12 can perform a power running operation and a regenerative operation, and is formed by a motor that is AC driven by an inverter 20, for example, an IPM (Interior Permanent Magnetic) motor.

  Thus, when the load on the engine 11 is large, the motor generator 12 is powered and the driving force of the motor generator 12 is transmitted to the hydraulic pumps 14L and 14R via the speed reducer 13. On the other hand, when the load of the engine 11 is small, the driving force of the engine 11 is transmitted to the motor generator 12 via the transmission 13 and generates power by the regenerative operation of the motor generator 12.

  The hydraulic pumps 14L and 14R supply hydraulic pressure to the hydraulic actuators such as the left and right traveling hydraulic motors 1L and 1R and the boom cylinder 7 via the control valve 17 to drive the hydraulic actuators.

  Further, when at least one of the motor generator 12 and the turning electric motor 21 is performing a power running operation, the battery 19 supplies necessary electric power to the motor generator 12 or the electric turning motor 21 and The electric power generated by the regenerative operation of the generator 12 or the turning electric motor 21 is stored.

  The charging / discharging of the battery 19 is controlled by the controller 30 in accordance with the state of charge and the operating state of the motor generator 12 and the turning electric motor 21, and the turning electric motor 21 is turned by the inertia rotation of the upper turning body 3. Regenerative electric power is generated through the reduction gear 24.

  The operating device 26 operates the turning electric motor 21, the lower traveling body 1, the boom 4, the arm 5, and the bucket 6. Further, the primary side hydraulic pressure supplied through the pilot line 25 is converted into a secondary side hydraulic pressure corresponding to the operation amount of the operating device 26 and is output to the control valve 17 to be travel hydraulic motors 1L, 1R, The pump discharge pressure P is taken on the horizontal axis that controls each hydraulic actuator such as the boom cylinder 7. A graph H0 in the figure is a constant horsepower control curve (QP characteristic curve) corresponding to a hydraulic load of a flat land traveling 2-speed linear drive, and a graph H1 is a traveling unit driven independently by a hydraulic load. This is a constant horsepower control curve set when the vehicle is running.

  FIG. 3 shows a specific example of a travel control circuit according to this embodiment. As shown in the figure, a regulator 33L is connected to the hydraulic pump 14L provided in the control circuit of the left traveling unit. Then, when the tilt angle of the regulator 33L is changed by a command signal (drive current i) from the controller 30, the discharge start pressure (output) of the hydraulic pump 14L at the maximum tilt angle, that is, the pump horsepower. It is configured to be able to adjust the settings.

  Further, a three-position switching type direction switching valve 34L is provided between the traveling hydraulic motor 1L and the hydraulic pump 14L. By switching the direction switching valve 34L from the neutral position to the left position or the right position, The traveling hydraulic motor 1L is driven to rotate counterclockwise or clockwise.

  Further, the pilot pressure of the direction switching valve 34L is detected by a pressure sensor (hydraulic sensor) 37 through the first shuttle valve 35L and the second shuttle valve 36, and a detection signal from the pressure sensor 37 is output to the controller 30. . Then, the controller 30 outputs a command signal based on the detection signal, thereby changing and adjusting the tilt setting of the regulator 33L to change the pump horsepower.

  Note that the control circuit for the right traveling unit including the regulator 33R, the hydraulic pump 14R, the direction switching valve 34R, and the like is the same as the control circuit for the left traveling unit, and a description thereof will be omitted.

  As shown in FIG. 4, the controller 30 determines whether the pump output control unit 38 that variably controls the outputs (horsepower) of the hydraulic pumps 14L and 14R and the traveling unit of the hybrid construction machine are driven independently by a hydraulic load. And a travel drive determination unit 39 for determining. When the traveling unit is driven independently by a hydraulic load, the output of the hydraulic pumps 14L and 14R is set to a constant value. The outputs of the hydraulic pumps 14L, 14R in this case are fixed so as to be larger by a predetermined value than the flat ground traveling second speed linear drive output (hydraulic load).

  Further, detection signals from various sensors 40 to 47 are input to the controller 30, and the controller 30 drives and controls the generator motor 12, the turning generator motor 21, and the battery 19 via the power controller 50 based on the detection signals. At the same time, the engine control device 51 and the control valve control device 52 are driven and controlled.

  In the hybrid construction machine according to the present embodiment, when the vehicle is traveling straight on a flat ground and the traveling unit is not driven by an electrical load and is driven to travel solely by the hydraulic pumps 14L and 14R, the direction switching valves 34L and 34R. Therefore, the first shuttle valves 35L, 35R and the second shuttle valve 36 are turned on and a detection signal (a hydraulic load single drive detection signal) is generated by the pressure sensor 37. It is output to the controller 30.

  Next, the travel drive determination unit 39 of the controller 30 determines that the travel unit is driven solely by a hydraulic load based on the detection signal, and transmits a signal to that effect to the pump output control unit 38. Then, the pump output control unit 38 fixes the horsepower setting so that the outputs of the hydraulic pumps 14L and 14R are larger than the flat-ground traveling second-speed linear drive output.

  Specifically, the pump output control unit 38 is set in the regulators 33L and 33R by outputting a command signal to supply a drive current i having a predetermined magnitude to an electromagnetic inverse proportional pressure reducing valve (not shown). By changing the tilt angle, the horsepower setting is changed so that the discharge pressures of the hydraulic pumps 14L and 14R are increased more than the flat ground traveling second speed linear drive pressure.

  FIG. 5 shows a constant horsepower control curve of the hydraulic pumps 14L and 14R, where the vertical axis represents the pump discharge amount Q and the horizontal axis represents the pump discharge pressure P. A graph H0 in the figure is a constant horsepower control curve (QP characteristic curve) corresponding to a hydraulic load of a flat land traveling 2-speed linear drive, and a graph H1 is a traveling unit driven independently by a hydraulic load. This is a constant horsepower control curve set when the vehicle is running.

  As is clear from the figure, the constant horsepower control curve H1 during traveling alone due to the hydraulic load is shifted to the right side from the constant horsepower control curve H0 in the flat ground traveling 2-speed straight drive. That is, the break point T1 of the constant horsepower control curve H1 corresponding to the torque output of the hydraulic pumps 14L, 14R at the maximum tilt angle is the breakpoint T0 (the pump discharge amount of the pump discharge amount) It is fixed so as to be larger than the pump discharge pressure P0 at the start of control by a predetermined value. The break points T0 and T1 are points corresponding to the pump discharge pressures P0 and P1 when the maximum pump discharge amount QM decreases, that is, when the pump discharge amount reduction control starts.

  As described above, according to the present invention, when the traveling unit is driven solely by a hydraulic load, the horsepower is set so that the discharge pressures of the left and right hydraulic pumps 14L and 14R are larger than the flat-ground traveling second speed linear drive pressure. Therefore, the hydraulic oil discharged from the left and right hydraulic pumps 14L, 14R is always kept at the maximum flow rate.

Accordingly, since the left and right hydraulic pumps 14L and 14R discharge the same amount of pressure oil from each other, there is no possibility of causing a flow rate difference between the discharged oils of the left and right hydraulic pumps 14L and 14R as in the conventional example. Accordingly, it is possible to prevent a flow rate difference from occurring in the hydraulic oil supplied to the left and right traveling hydraulic motors 1L and 1R. Thus, even when the left and right hydraulic pumps 14L and 14R are driven by the engine 11 alone, a stable traveling straightness can be ensured for a long time.

  It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

1 is a side view of a hybrid construction machine according to an embodiment of the present invention. 1 is a block diagram of a hydraulic circuit according to one embodiment. The travel control circuit diagram which concerns on one Example. 1 is a block diagram illustrating a configuration including a controller and peripheral devices according to an embodiment. The graph explaining the horsepower constant control curve of the hydraulic pump which concerns on one Example.

Explanation of symbols

1 Lower traveling body 1L Left traveling hydraulic motor 1R Right traveling hydraulic motor 2 Turning mechanism 11 Engine 12 Motor generator 13 Transmission 14L Left hydraulic pump (variable displacement hydraulic pump)
14R Right hydraulic pump (variable displacement hydraulic pump)
17 Control valve 18 Inverter 19 Battery (power storage device)
20 Inverter

Claims (2)

Left and right traveling hydraulic motors that drive the left and right traveling units; left and right hydraulic pumps that supply pressure oil to the traveling hydraulic motor; a motor generator that performs regenerative power generation using surplus power of the hydraulic drive unit; The hydraulic pump comprising: a power storage device that charges the regenerated power; and a controller that comprehensively controls each drive unit of the electric system such as the motor generator, and the hydraulic pump according to the output of the engine and / or the output of the power storage device In a traveling control circuit of a hybrid construction machine configured to be able to travel by driving
A traveling control circuit for a hybrid construction machine, characterized in that the engine output is set to be larger than a flat ground traveling 2-speed linear drive output. Left and right traveling hydraulic motors that drive the left and right traveling units; left and right hydraulic pumps that supply pressure oil to the traveling hydraulic motor; a motor generator that performs regenerative power generation using surplus power of the hydraulic drive unit; The hydraulic pump comprising: a power storage device that charges the regenerated power; and a controller that comprehensively controls each drive unit of the electric system such as the motor generator, and the hydraulic pump according to the output of the engine and / or the output of the power storage device In a traveling control circuit of a hybrid construction machine configured to be able to travel by driving
The controller includes a pump output control unit that variably controls the output of the hydraulic pump, and a travel drive determination unit that determines whether the travel unit is driven solely by a hydraulic load, and the travel unit includes the hydraulic load. When the vehicle is driven independently, the traveling control circuit for the hybrid construction machine is set so that the output of the hydraulic pump is larger than the output of the straight traveling 2nd straight drive.

Images