JP2014145225A - Hybrid construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure regenerative brake action by consuming regenerative energy of a slewing motor without using a regenerative resistor and without causing excessive increase in speed of an engine.SOLUTION: A hybrid construction machine is configured so as to make a generator motor 11 be driven by regenerative power of a slewing motor 26 to perform engine assist action as emergency control in the case of deceleration of slewing while performing pump flow control of increasing a tilt of an oil hydraulic pump 12 to increase a pump flow and pump pressure control of narrowing an aperture of a variable unloading valve 21 to raise pump discharge pressure, when power storage device failure detection means 29 detects a failure of a power storage device 27.

Description

  The present invention relates to a hybrid construction machine in which a hydraulic pump and a generator motor are driven by an engine, and an upper swing body is driven to swing by a swing motor.

  The background art will be described using an excavator as an example.

  As shown in FIG. 3, the excavator is mounted on a crawler type lower traveling body 1 so that an upper swing body 2 can be swung around an axis X that is perpendicular to the ground. The front attachment 3 is attached and configured.

  The front attachment 3 includes a boom 4 that can be raised and lowered, an arm 5 attached to the tip of the boom 4, a bucket 6 attached to the tip of the arm 5, and a boom and an arm that are hydraulic actuators for driving them. The bucket is composed of cylinders 7-9.

  In addition, a swing electric motor is used as a swing drive source of the upper swing body 2 in the hybrid excavator.

  In this hybrid excavator, a hydraulic pump and a generator motor are driven using an engine as a power source, and a hydraulic actuator is driven by the hydraulic pump. On the other hand, a swing motor is formed by a generator motor and a power storage device charged by the output of the generator motor. A driving structure is adopted (see Patent Documents 1 and 2).

  In addition, the regenerative electric power generated in the turning electric motor during the turning deceleration is charged in the power storage device.

  In this hybrid excavator, the power storage device may fail due to a relay down or the like.

  When this power storage device failure occurs, there is a problem that the regenerative brake does not work because there is no tray for the regenerative power generated by the swing motor during deceleration.

  As a countermeasure, it is conceivable to consume the regenerative energy by driving the generator motor with the regenerative electric power of the swing motor and assisting the engine, but this causes a problem that the engine is excessively accelerated.

  Further, as a solution to such a problem, a technique is known in which a regenerative resistor is provided and the regenerative power of the swing motor is consumed by the regenerative resistor, thereby ensuring a regenerative braking action without causing an increase in engine speed. (See Patent Document 3).

JP 2000-283107 A Japanese Patent Laid-Open No. 10-42587 Japanese Patent No. 4609567

  However, according to the known technique described in Patent Document 3, since a regenerative resistor and its control device must be added only when the power storage device fails, it is difficult to lay out the equipment, particularly in an excavator with severe space restrictions. And the cost increases.

  Accordingly, the present invention provides a hybrid construction machine capable of ensuring a regenerative braking action by consuming regenerative energy of a swing motor without using regenerative resistance and without causing excessive acceleration of the engine. It is.

  As means for solving the above problems, in the present invention, a lower traveling body, an upper swinging body that is pivotably mounted on the lower traveling body, a variable displacement hydraulic pump as a hydraulic source of a hydraulic actuator, A pump regulator that controls the discharge amount of the hydraulic pump, a variable pressure control valve provided between the hydraulic pump and the tank, and a generator motor that performs a generator action and a motor action to assist the engine An engine as a power source for the hydraulic pump and the generator motor, a swing motor as a swing drive source for the upper swing body, and a power storage device that transfers power between the generator motor and the swing motor, A power storage device failure detection means for detecting a failure of the power storage device; and a control means for controlling the operation of the generator motor and the swing motor and the charge / discharge of the power storage device. The control means causes the generator motor to perform a motor action by the regenerative power of the swing motor as emergency control at the time of turning deceleration when a failure of the power storage apparatus is detected by the power storage apparatus failure detection means. The pump regulator is configured to perform at least one of pump flow control for increasing the discharge amount of the hydraulic pump and pump pressure control for increasing the pump discharge pressure by reducing the opening of the pressure control valve.

  According to this configuration, in a situation where the power storage device becomes unusable due to a failure, the regenerative power generated in the swing motor at the time of turning deceleration is consumed as the driving force of the generator motor, and at the same time, one of the pump flow rate and the pump pressure, that is, By performing emergency control that intentionally increases the hydraulic load, the engine load can be increased and the speed increase can be suppressed.

  That is, the regenerative energy of the swing motor can be consumed by the hydraulic load to secure the regenerative braking action, and the upper swing body can be safely stopped.

  In addition, unlike the known technique described in Patent Document 3, there is no need to add a regenerative resistor and its control device, which is advantageous in terms of equipment layout and cost.

  In addition, when the pump discharge rate increase control is used as emergency control, the existing equipment such as the pump and its control system can be used for emergency control in a hybrid construction machine equipped with a variable displacement hydraulic pump. Therefore, the effects of facilitating device layout and reducing costs are enhanced.

  In the present invention, a control valve for controlling the operation of the hydraulic actuator and an actuator operating means for operating the control valve are provided, and the control means has a discharge amount of the hydraulic pump according to an operation amount of the actuator operating means. It is desirable to configure so as to control at least one of the opening degrees of the pressure control valve.

  According to this configuration, in the hybrid construction machine that controls at least one of the flow rate and pressure of the hydraulic pump according to the operation amount of the actuator operating means, one or both of the existing hydraulic pump and pressure control valve and its control system are connected Since it can be used for control as it is, the effect of facilitating the device layout and reducing the cost is further enhanced.

  Further, in the present invention, it is preferable that an actuator operation stop unit for stopping the operation of the hydraulic actuator is provided, and the control unit is configured to stop the operation of the hydraulic actuator by the actuator operation stop unit during the emergency control. (Claims 3 and 4).

  According to this configuration, it is possible to prevent the hydraulic actuator from performing an operation contrary to the operator's intention during emergency control, that is, in a state where the pump flow rate or pressure is increased.

  In this case, a hydraulic pilot switching type control valve for controlling the operation of the hydraulic actuator, a remote control valve for operating the control valve with a pilot pressure, and a pilot pump for supplying a pilot primary pressure to the remote control valve, As an actuator operation stop means, it is desirable to provide a pilot primary pressure switching valve for supplying / blocking the pilot primary pressure in a pilot primary pressure line connecting the pilot pump and the remote control valve.

  According to this configuration, during emergency control, the pilot primary pressure switching valve shuts off the low-pressure pilot primary pressure line so that the control valve cannot be switched to stop the operation of the actuator, so the high-pressure actuator circuit is shut off. Compared to the case, a small and inexpensive switching valve for low pressure can be used.

  In the present invention, there is provided a turning motion detecting means for detecting whether or not the upper turning body is in a turning motion, and the control means cancels the emergency control when the turning stop is detected by the turning motion detection means. In addition, it is desirable that the actuator operation stop by the actuator operation stop means is canceled.

  According to this configuration, emergency control is canceled when turning is stopped, the pump flow rate and pressure are returned to the normal state, and the hydraulic actuator can be operated.Therefore, measures for ensuring safety (moving the machine to a safe place, It is possible to install a front attachment).

  In the present invention, it is desirable that the control means is configured to disconnect the power storage device from the generator motor and the swing motor during the emergency control.

  According to this configuration, it is possible to avoid a situation where the power storage device is damaged by disconnecting the failed power storage device from the power system.

  According to the present invention, the regenerative braking action can be ensured by consuming the regenerative energy of the swing electric motor without using the regenerative resistance and without causing excessive acceleration of the engine.

1 is a system configuration diagram of a hybrid excavator according to an embodiment of the present invention. It is a flowchart for demonstrating the effect | action of the shovel. It is a schematic side view of a hybrid excavator.

  The embodiment is applied to a hybrid excavator.

  FIG. 1 shows the system configuration of this hybrid excavator.

As shown in the figure, an engine 10 as a power source is connected to a generator motor 11 that performs a generator action and a motor action, a hydraulic pump (main pump) 12 and a pilot pump 13 as a hydraulic source of a hydraulic actuator, These are driven by the engine 10.

  The hydraulic pump 12 is connected to a boom cylinder and other hydraulic actuators (collectively denoted by reference numeral “15”) via a control valve 14, and the hydraulic actuator 15 is supplied with pressure oil supplied from the hydraulic pump 12. Is driven.

  The control valve 14 is provided for each of the plurality of hydraulic actuators, but only one is shown here as a representative.

  The hydraulic pump 12 is configured as a variable displacement pump in which the tilt is controlled by the operation of the pump regulator 17 based on the tilt command from the controller 16 constituting the control means, and the discharge amount (pump flow rate) changes.

  The control valve 14 is configured as a hydraulic pilot switching valve that is switched between a neutral position A and both side operating positions B and C by a pilot pressure (pilot secondary pressure) from a remote control valve 18 as an actuator operating means. At the position A, the connection between the hydraulic pump 12 and the tank T and the hydraulic actuator 15 is cut off.

  A control valve with a center bypass passage is used as the control valve 14, and a center bypass line leading to the tank is provided vertically through the center bypass passage of each control valve. You may take the well-known circuit structure closed with a cut valve. In short, any circuit configuration that can cut off the connection between the hydraulic pump 12 and the tank T and the hydraulic actuator 15 in the neutral state of the control valve may be used.

  Between the pump line 19 connecting the hydraulic pump 12 and the control valve 14 and the tank T, a relief valve 20 for setting the maximum pressure of the circuit and a variable unloading valve 21 as a pressure control valve are provided in parallel.

  The variable unloading valve (hereinafter simply referred to as “unloading valve”) 21 is configured as a hydraulic pilot valve whose opening degree changes depending on the pilot pressure from the outside, and corresponds to an unloading valve opening command from the controller 16. The opening degree of the unload valve 21 is controlled by an electromagnetic proportional valve 22 that outputs a pilot pressure, and thereby the discharge pressure (pump pressure) of the hydraulic pump 12 is controlled.

  In addition, an electromagnetic pilot primary pressure switching valve 24 as an actuator operation stop means is provided in a pilot primary pressure line 23 for sending pilot pressure from the pilot pump 13 to the primary side of the remote control valve 18 as pilot primary pressure.

  The pilot primary pressure switching valve (hereinafter simply referred to as “switching valve”) 24 switches between the open position A and the shut-off position B based on a switching command from the controller 16. The pilot primary pressure is supplied to the remote control valve 18 so that the control valve 14 can be controlled by the remote control valve 18, that is, the hydraulic actuator 15 can be operated.

  On the other hand, when the switching valve 24 is switched to the cutoff position B, the supply of the pilot primary pressure to the remote control valve 18 is shut off and the primary side of the remote control valve communicates with the tank T. As a result, the control valve 14 cannot be controlled by the remote control valve 18, the control valve 14 returns to neutral, and the operation of the hydraulic actuator 15 stops.

  Further, the operation amount of the remote control valve 18 is detected by an operation amount detecting means (not shown) (for example, a pressure sensor for detecting the pilot pressure of the remote control valve 18) and input to the controller 16, and the hydraulic pump according to the operation amount of the remote control valve 18 The controller 16 controls the inclination 12 (pump flow rate) and the opening degree (pump pressure) of the unload valve 21.

  In this way, the controller 16 is configured to control the tilt (pump flow rate) of the hydraulic pump 12, the opening degree (pump pressure) of the unload valve 21, and the operation / stop of the hydraulic actuator 15. .

The electric generator motor 11 is connected to a swing motor 26 and a power storage device 27 via an inverter 25 that constitutes a control means together with the controller 16, and the swing motor 26 is generated by the generated power of the generator motor 11 and the stored power of the power storage device 27. When driven, the upper swing body 2 rotates.

  In addition, the power generated by the generator motor 11 and the regenerative power generated in the swing motor 26 during the deceleration of the turn are sent to the power storage device 27 and charged at an appropriate time.

  The inverter 25 controls transmission / reception of electric power between the generator motor 11, the swing motor 26, and the power storage device 27, that is, charging / discharging of the power storage device 27 and driving of the generator motor 11 and the swing motor 26.

  Further, a switch 28 is provided between the inverter 25 and the power storage device 27 to connect / cut off both in accordance with an opening / closing command from the controller 16.

  The switch 28 is closed when the power storage device 27 is in a healthy state, connects the inverter 25 and the power storage device 27, and shuts off both of them when the power storage device failure detection means 29 detects a failure of the power storage device 27. The device 27 is disconnected from the power system (the generator motor 11 and the swing motor 26).

  Further, a turning speed sensor 30 is provided as a turning motion detecting means for detecting the turning speed of the upper turning body 2, and a detection signal (turning speed signal) of the sensor 30 is input to the controller 16.

  The power storage device failure detection means (hereinafter simply referred to as “failure detection means”) 29 determines whether or not the power storage device 27 has failed from the detected value of the voltage of the DC bus connecting the inverter 25 and the power storage device 27 (unusable). A failure signal is sent to the controller 16 when a failure is determined.

  Based on the failure signal and the turning speed signal, the controller 16 performs emergency control as turning control instead of normal control when the power storage device is normal.

  This control content will be described with reference to the flowchart of FIG.

  For example, when the control is started due to the turning operation, it is determined in step S1 whether or not the power storage device 27 has failed.

  If NO (no failure), the process proceeds to step S2, and normal control, that is, normal control for controlling the rotational speed of the swing motor 26 according to the operation amount of the swing operation lever (not shown) is started.

  On the other hand, if the answer is YES (failed) in step 2, the next emergency control is performed.

  First, in step S3, the switching position of the switching valve 24 is switched to (B), and in step S4, the switch 28 is opened to shut off the inverter 25 and the power storage device 27.

  As a result, the pilot primary pressure line 23 of the remote control valve 18 is shut off, the control valve 14 becomes inoperable, the operation of the hydraulic actuator 15 stops, and the power storage device 27 in the failed state is connected to the power system (the generator motor 11 and the swing motor). 26).

  In step S5, the tilt of the hydraulic pump 12 is increased through the pump regulator 17, and the opening degree of the unload valve 21 is reduced in step S6.

  The pump flow rate and pump pressure of the hydraulic pump 12, that is, the hydraulic load increases due to the increase of the pump tilt and the opening restriction of the unload valve 21.

  In step S7, the generator motor 11 is driven by the regenerative electric power generated in the turning motor 26 at the time of turning deceleration, and the engine assist operation is started.

  Thus, by increasing the hydraulic load (engine load) and the engine assist operation at the same time, the regenerative electric power of the swing motor 26 is consumed by the generator motor 11 and the regenerative brake is operated, thereby suppressing the acceleration of the engine 10. it can.

  In step S8, it is determined whether or not the turning speed has become 0 as a result of the regenerative braking, that is, whether or not the turning has been stopped. If NO, the process returns to step S3 and the emergency control is continued.

  On the other hand, if “YES” is determined in the step S8, the pump tilting and the unloading valve opening are returned to the normal state in a step S9, the switching valve 24 is returned to the open position “a” in a step S10, and To stop emergency control.

  In this manner, in a situation where the power storage device 27 becomes unusable due to a failure, the regenerative power generated in the swing motor 26 at the time of turning deceleration is consumed as the driving force of the generator motor 11, and at the same time, the pump flow rate and the pump pressure, that is, the hydraulic pressure By performing emergency control that intentionally increases the load, it is possible to increase the engine load and suppress the speed increase.

  That is, the regenerative energy of the swing motor 26 can be recovered with a hydraulic load to ensure a regenerative braking action, and the upper swing body 2 can be safely stopped.

  In addition, unlike the known technique described in Patent Document 3, there is no need to add a regenerative resistor and its control device, which is advantageous in terms of equipment layout and cost.

  In addition, since the equipment for hydraulic control originally provided in the hybrid excavator, such as the hydraulic pump 12 and the unload valve 21 and its control system, can be used for emergency control, the equipment layout can be simplified and the cost can be reduced. Get higher.

  Furthermore, since the operation of the hydraulic actuator 15 is stopped during emergency control, it is possible to prevent the hydraulic actuator 15 from performing an operation contrary to the operator's intention while the flow rate and pressure of the hydraulic pump 12 are increased.

  In this case, since the actuator operation is stopped by shutting off the low pressure pilot primary pressure line 23 by the switching valve 24 and making the control valve 14 non-switchable, the switching valve is compared with the case where the high pressure actuator circuit is shut off. 24 can be a low-pressure small and inexpensive one.

  On the other hand, since the failed power storage device 27 is disconnected from the generator motor 11 and the swing motor 26 during emergency control, a situation in which the power storage device 27 is damaged can be avoided.

  Further, when turning is stopped as a result of the emergency control, the emergency control is canceled, that is, the pump tilting and the unloading valve opening are returned to the normal state, and the switching valve 24 is opened to enable the actuator operation. Therefore, it is possible to take measures for ensuring safety (moving the machine to a safe place, installing a front attachment, etc.).

Other embodiments
(1) In the above embodiment, both the pump flow rate and the pump pressure are increased as emergency control, but only one of them may be increased.

  (2) In the above embodiment, the existing unload valve 21 and its control system are used as the pressure control valve for increasing the pump pressure, but another pressure control valve and its control system are added. Also good.

  (3) The present invention is not limited to the hybrid excavator and can be widely applied to other hybrid construction machines having the same basic configuration as this.

DESCRIPTION OF SYMBOLS 1 Lower traveling body 2 Upper turning body 10 Engine 11 Generator motor 12 Hydraulic pump 14 Control valve 15 Hydraulic actuator 16 Controller which comprises a control means 17 Pump regulator 18 Remote control valve 19 Pump line 21 Variable unload valve 22 Control variable unload valve Proportional solenoid valve 23 Pilot primary pressure line 24 Pilot primary pressure switching valve as actuator operation stop means 25 Inverter constituting control means 26 Rotating motor 27 Power storage device 28 Switch 29 Power storage device failure detection means 30 Rotation motion detection means Swivel speed sensor

Claims (6)

  A lower traveling body, an upper swinging body that is rotatably mounted on the lower traveling body, a variable displacement hydraulic pump as a hydraulic source of a hydraulic actuator, a pump regulator that controls a discharge amount of the hydraulic pump, A pressure control valve having a variable opening provided between the hydraulic pump and the tank, a generator motor that performs a generator action and a motor action for assisting the engine, and a power source for the hydraulic pump and the generator motor. An engine, a swing motor as a swing drive source of the upper swing body, a power storage device that transfers power between the generator motor and the swing motor, and a power storage device failure detection unit that detects a failure of the power storage device And control means for controlling the operation of the generator motor and the swing motor and charging / discharging of the power storage device, and the control means is connected to the power storage device failure detection means. When a failure of the power storage device is detected, as an emergency control during turning deceleration, the regenerative power of the turning motor causes the generator motor to perform a motor action, and the pump regulator increases the discharge amount of the hydraulic pump. A hybrid construction machine configured to perform at least one of pump flow rate control and pump pressure control for increasing pump discharge pressure by narrowing the opening of the pressure control valve.   A control valve for controlling the operation of the hydraulic actuator; and an actuator operating means for operating the control valve. The control means includes a discharge amount of the hydraulic pump and a pressure control valve according to an operation amount of the actuator operating means. The hybrid construction machine according to claim 1, wherein at least one of the opening degrees is controlled.   The actuator operation stop means for stopping the operation of the hydraulic actuator is provided, and the control means is configured to stop the operation of the hydraulic actuator by the actuator operation stop means during the emergency control. 2. The hybrid construction machine according to 2.   A hydraulic pilot switching type control valve for controlling the operation of the hydraulic actuator, a remote control valve for operating the control valve with a pilot pressure, and a pilot pump for supplying a pilot primary pressure to the remote control valve, and stopping the operation of the actuator 4. The hybrid construction machine according to claim 3, wherein a pilot primary pressure switching valve for supplying / cutting off the pilot primary pressure is provided in a pilot primary pressure line connecting the pilot pump and the remote control valve as means.   A swing motion detecting means for detecting whether or not the upper swing body is in a swing motion, and the control means cancels the emergency control when the swing stop is detected by the swing motion detection means; The hybrid construction machine according to claim 3 or 4, wherein the actuator operation stop by the actuator operation stop means is released.   The hybrid construction machine according to any one of claims 1 to 5, wherein the control means is configured to disconnect the power storage device from the generator motor and the swing motor during the emergency control.

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