JP2014218855A - Hybrid construction machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a slewing braking action while employing a configuration that recovers regenerative energy as engine assist power.SOLUTION: In a hybrid shovel, an engine load is increased by operating an exhaust brake gear 9, which is provided in an exhaust system of an engine 1, as slewing braking control for exerting a slewing braking force by recovering regenerative electric power generated in a slewing motor 5, during slewing deceleration. In this state, the engine 1 is assisted by making a generator motor 2 perform a motor action by the regenerative electric power.

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.

  The excavator is mounted on a crawler-type lower traveling body so that the upper swing body can swing around an axis perpendicular to the ground, and the upper swing body includes a boom, an arm, and a bucket. Installed and configured.

  Moreover, a turning electric motor is used in a hybrid excavator as a turning drive source of the upper turning body.

  In this hybrid excavator, a hydraulic pump and a generator motor are driven by an engine, and a hydraulic actuator is driven by a hydraulic pump, while a swing motor is driven by a generator motor and a capacitor charged by the output of the generator motor Is taken.

  In addition, the regenerative power generated in the swing motor during the deceleration of the turn is stored in a capacitor, and the regenerative power is collected by this power storage action so as to exert a braking force (see Patent Document 1).

JP 2008-115640 A

  According to the known technology that relies solely on the storage action of the storage battery as described above, when the storage capacity is reduced due to low temperature or deterioration of the storage battery, the regenerative power cannot be absorbed and sufficient rotation braking cannot be performed. The certainty and reliability of turning braking are low.

  As a countermeasure, it is conceivable that the regenerative energy is consumed by driving the generator motor with the regenerative power of the swing motor and assisting the engine.

  However, for example, when the engine load is small, such as when the hydraulic actuator is stopped, the power required for engine assist (assist power) is also small, and thus there is a possibility that the regenerative energy cannot be absorbed.

  As another measure, it is conceivable that a regenerative resistor is provided and a regenerative brake is operated by consuming the regenerative power of the swing motor by the regenerative resistor.

  However, according to this configuration, it is necessary to add a relatively large regenerative resistor, its control device, and equipment for processing the heat generated by the regenerative resistor. It becomes difficult and the cost is greatly increased.

  Accordingly, the present invention provides a hybrid construction machine that can obtain a reliable turning braking action while taking a configuration in which regenerative energy is recovered as engine assist power.

  As means for solving the above-mentioned problems, in the present invention, a lower traveling body, an upper swing body that is pivotably mounted on the lower traveling body, a swing motor as a swing drive source of the upper swing body, and an engine And a generator motor connected to the engine to perform a generator action and a motor action, a capacitor, an exhaust brake device for increasing an engine load provided in the exhaust system of the engine, and a control means, The control means operates the exhaust brake device to increase the engine load as the turning braking control for collecting the regenerative electric power generated in the turning electric motor and exerting the turning braking force at the time of turning deceleration. The regenerative electric power causes the generator motor to perform an electric motor action to assist the engine.

  According to this configuration, at the time of turning deceleration, the exhaust brake device provided in the exhaust system of the engine is operated to increase the engine load, and in this state, the engine assisting action is performed by the generator motor. Electric power is consumed as engine assist power, and a necessary turning braking action can be ensured.

  That is, the reliability and reliability of turning braking can be improved as compared with the case where turning braking is performed only by the power storage action of the capacitor.

  In addition, the power storage function for turning braking becomes unnecessary, or even when the power storage function is used in combination, the power storage capacity can be reduced, so that the battery can be miniaturized.

  In addition, the exhaust brake device only needs to be provided with a valve that throttles exhaust gas in the exhaust pipe of the engine and its drive unit, and the equipment is much smaller and less expensive than when a regenerative resistor is provided. For this reason, it can be applied easily and at low cost to an excavator with severe space restrictions.

  In the present invention, the control means may be configured to execute the turning braking control when a charging rate of the battery exceeds a set value as an upper limit value capable of storing the regenerative power (claim) Item 2).

  In this way, when the charging rate of the battery is below the set value, the regenerative brake is activated by the power storage action, and when it is above the set value, the engine assist action is switched to, or both are used in combination.

  Further, in the present invention, there is provided a turning speed detecting means for detecting a turning speed of the upper turning body, and the control means uses the braking force of the exhaust brake device according to the turning speed as a turning braking control. It is desirable to configure so as to control in a higher direction.

  Further, in the present invention, a turning speed detecting means for detecting a turning speed of the upper turning body is provided, and the control means outputs an output for engine assist of the generator motor according to the turning speed as the turning braking control. Therefore, it is desirable to control in the direction of increasing on the high speed side.

  Further, according to the third and fourth aspects of the present invention, only the necessary turning brake force works according to the turning speed, so that waste of power (exhaust brake force or engine assist power) can be avoided.

  According to the present invention, a reliable turning braking action can be obtained while taking a configuration in which regenerative energy is recovered as engine assist power.

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 turning braking effect | action of the embodiment. It is a figure for demonstrating the judgment method at the time of turning deceleration in the same embodiment. It is a figure which shows the relationship between the turning speed and exhaust brake force in the same embodiment. It is a figure which shows the relationship between the turning speed and the assist output of a generator motor in the embodiment.

  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 1 as a power source is connected to a generator motor 2 that performs a generator action and a motor action, and a hydraulic pump 3 as a hydraulic source of a hydraulic actuator, and these are driven by the engine 1.

  The hydraulic pump 3 is connected to a hydraulic actuator such as a boom cylinder (not shown) via a control valve, and the hydraulic actuator is driven by pressure oil supplied from the hydraulic pump 3.

  The generator motor 2 is driven by the engine 1 to perform a generator action, and the generated electric power is sent to the capacitor 4 to be charged (charged), while the generator motor 2 performs the motor action by the electric power of the capacitor 4 when appropriate. Go and assist engine 1.

  Further, a turning electric motor 5 as a turning drive source, a controller 6 such as an electric motor, and a controller 7 constituting a control means are provided, and an operation state (operation direction and operation amount) of the turning operation lever 8 as a turning operation means, Based on the state of charge of the battery 4, the controller 7 and the controller 6 such as an electric motor actuate the generator motor 2, the swing motor 5, and the battery 4 (operation / stop of the generator motor 2 and the swing motor 5, charging / discharging of the battery 4, etc.) Is controlled.

  The turning electric motor 5 is driven by the electric power generated by the generator motor 2 or the electric power of the battery 4 and performs a regenerative action during the turning deceleration.

  Then, as will be described later, the regenerative power generated in the generator motor 2 is sent as stored power to the capacitor 4 under the condition that the charging rate is equal to or lower than the set value, and if the charging rate is equal to or higher than the set value, the generator motor 2 is subjected to engine assist. Is sent as drive power.

  Further, an exhaust brake device 9 is provided in the exhaust system of the engine 1 as means for increasing the engine load and increasing the power required for engine assist (engine assist power).

  The exhaust brake device 9 is composed of a shutter valve provided in the middle of the exhaust pipe 10 and its drive unit (not shown), similar to that used for large vehicles such as trucks. When the engine is operated to the closed side, the exhaust brake is activated and the engine load increases.

  On the other hand, as a detecting means, a turning operation detecting means (for example, a pressure sensor for detecting a pilot pressure generated by operation of a turning remote control valve) 11 for detecting an operation state of the turning operation lever 8 and a rotation speed of the turning electric motor 5 are set to the upper part. A turning speed detecting means 12 for detecting the turning speed of the turning body and a charging rate detecting means 13 for detecting the charging rate of the battery 4 are provided. Detection signals (turning operation signal, turning speed signal, charging rate signal) from these are provided. Is sent to the controller 7.

  Based on the turning operation signal from the turning operation detecting means 11, the controller 7 determines whether or not the vehicle is turning and decelerating. The regenerative electric power to be recovered is collected by the engine assisting action of the generator motor 2 and the turning braking control is performed to exert the turning braking force.

  The judgment at the time of turning deceleration is, for example, a temporal change of the turning pilot pressure (the past pilot pressure shown in FIG. 3) according to the operation of the turning operation lever 8 (the operation that is powered back in one direction and then returned to the neutral side). And comparison of current pilot pressure).

  Alternatively, the acceleration / deceleration operation itself of the turning operation lever 8 may be electrically detected by a potentiometer or the like.

  On the other hand, the controller 7 has preset characteristics of the exhaust brake force (shutter valve closing amount) with respect to the turning speed and the characteristics of the assist output of the generator motor 2 with respect to the turning speed shown in FIG. It is remembered.

  That is, the exhaust brake force and the engine assist output are both set to be higher on the high speed side according to the turning speed (higher in proportion to the turning speed).

  Further, as shown in FIGS. 4 and 5, the exhaust brake force and the assist output are set so as to work in a turning speed region that is equal to or higher than a set value that requires a braking action.

  Further, the controller 7 is preset with a set value as an upper limit value for storing the regenerative power generated in the swing motor 5 at the time of turning deceleration with respect to the charging rate of the battery 4, and the detected charging rate is set. The turning brake control by the exhaust brake and the engine assist is executed on condition that the value is equal to or less than the value.

  The operation of the controller 7 will be described with reference to the flowchart of FIG.

  After the start of control, it is determined whether or not the charging rate of the battery 4 is greater than or equal to the set value in step S1, that is, whether or not there is a margin for storing electricity, and whether or not the vehicle is decelerating in step S2. Don't go to the next step.

  On the other hand, if YES is determined in both steps S1 and S2 (when the vehicle cannot decelerate and the vehicle is decelerating), an exhaust brake operation corresponding to the turning speed is commanded in step S3 based on the exhaust brake characteristics of FIG. In step S4, an assist output corresponding to the turning speed is commanded based on the generator motor assist output characteristic of FIG.

  In this way, by causing the generator motor 2 to perform the engine assist operation with the engine load increased by the exhaust brake operation, the regenerative power generated in the swing motor 5 is consumed as engine assist power, and the necessary swing braking operation is performed. Can be secured.

  That is, the reliability and reliability of the turning braking can be improved as compared with the case where the turning braking is performed only by the power storage action of the battery 4.

  In addition, since the battery 4 performs a power storage function only when the charging rate is equal to or lower than the set value during turning deceleration, it is possible to reduce the power storage capacity and reduce the size.

  In addition, the exhaust brake device 9 only needs to be provided with a valve (shutter valve) that throttles exhaust gas in the exhaust pipe 10 of the engine 1 and its drive unit, and the equipment is much smaller and less expensive than the case where a regenerative resistor is provided. . For this reason, it can be applied easily and at low cost to an excavator with severe space restrictions.

  On the other hand, in order to increase the exhaust brake force and the engine assist output of the generator motor 2 as the turning speed increases, only the necessary turning brake force works according to the turning speed, and the power (engine assist power or exhaust brake force) is reduced. Wasted money can be avoided.

Other embodiments
(1) Since the storage capacity of the storage battery 4 decreases due to a decrease in temperature, the storage brake temperature is detected. If the storage battery temperature is below the set value even when the charge rate is below the set value during turning deceleration, the exhaust brake and engine You may make it perform turning braking control by assist.

  (2) In the above-described embodiment, when the charging rate is equal to or lower than the set value, the braking action by the power storage effect of the battery 4 is performed. In other words, when the charging rate is equal to or higher than the set value, turning by the exhaust brake and the engine assist Although the configuration in which the control is switched to the braking control is adopted, the configuration in which the power storage operation of the battery 4 and the turning braking control are simultaneously performed when the charging rate is equal to or lower than the set value may be employed.

  Alternatively, regardless of the charging rate of the battery 4, only the turning braking control is always performed at the time of turning deceleration, and the battery 4 may be made to perform only daily charging.

  (3) In the above embodiment, both the exhaust brake force and the engine assist force of the generator motor 2 are increased in proportion to the increase in the turning speed, but only one of them may be increased.

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

DESCRIPTION OF SYMBOLS 1 Engine 2 Generator motor 4 Accumulator 5 Turning motor 6 Controller etc. 7 Controllers which comprise control means 8 Turning operation lever 9 Exhaust brake device 10 Exhaust pipe 11 Turning operation detection means 12 Turning speed detection means 13 Charging rate detection means 13

Claims (4)

  A lower traveling body, an upper swing body mounted on the lower traveling body in a freely swingable manner, a swing motor as a swing drive source of the upper swing body, an engine, and a generator action and an electric motor connected to the engine A generator motor that operates, an electric storage device, an exhaust brake device for increasing an engine load provided in the exhaust system of the engine, and a control means; As the turning braking control for collecting the regenerative power generated and exerting the turning braking force, the exhaust brake device is operated to increase the engine load, and the regenerative power causes the generator motor to perform a motor action. A hybrid construction machine configured to assist the engine.   The said control means is comprised so that the said turning braking control may be performed when the charging rate of the said capacitor | condenser exceeds the setting value as an upper limit which can store the said regenerative electric power. Hybrid construction machine.   A turning speed detecting means for detecting a turning speed of the upper turning body is provided, and the control means controls the braking force of the exhaust brake device in a direction of increasing on the high speed side according to the turning speed as the turning braking control. The hybrid construction machine according to claim 1, wherein the hybrid construction machine is configured as described above.   A turning speed detecting means for detecting a turning speed of the upper turning body is provided, and the control means increases the output for engine assist of the generator motor on the high speed side according to the turning speed as the turning braking control. The hybrid construction machine according to any one of claims 1 to 3, wherein the hybrid construction machine is configured to be controlled in a direction.

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