JP6004853B2 - Work machine - Google Patents

Description

  The present invention relates to a work machine equipped with a power supply device that converts a power supply voltage to generate a DC voltage required for an electric load.

  In order to operate a plurality of electric devices mounted on a work machine such as an excavator, a DC voltage converter (DC-DC converter) that converts the output voltage of the power storage device into a required voltage and outputs the voltage to each electric device. Used. DC power is supplied from the power storage device to the cell motor for starting the engine. For this reason, when the engine is started, the discharge current of the power storage device temporarily increases.

JP 2011-155837 A

When the discharge current of the power storage device temporarily increases, the voltage applied to the primary winding of the DC voltage converter decreases. If this voltage drop increases, the voltage supplied to each electrical device may not meet the standard value.
An object of the present invention is to provide a work machine equipped with a power supply device capable of maintaining the voltage supplied to each electric device within a required range even when the output voltage of the power storage device decreases.

According to one aspect of the invention,
DC power supply,
A transformer including a primary winding and a first secondary winding;
A switching circuit that switches current from the DC power source and applies the current to the primary winding of the transformer;
A first rectifier circuit for rectifying alternating current appearing in the first secondary winding;
A booster circuit for boosting the output of the first rectifier circuit and generating a power supply voltage for an analog circuit ;
A cell motor connected to the DC power source;
An engine activated by the cell motor;
Is provided.

  By arranging the booster circuit, the power supply voltage for the analog circuit can be maintained at the target rated value even if the output voltage of the DC power supply temporarily decreases.

FIG. 1 is a block diagram of a power supply device mounted on a work machine according to an embodiment. FIG. 2 is an equivalent circuit diagram of a booster circuit used in the power supply device mounted on the work machine according to the embodiment. FIG. 3 is a graph illustrating an example of a temporal change in voltage of each part of the power supply device mounted on the work machine according to the embodiment. 4A is a block diagram of a power supply device according to a comparative example, and FIG. 4B is a graph illustrating an example of a temporal change in voltage of each part of the power supply device according to the comparative example. FIG. 5 is a side view of an excavator as an example of a work machine according to the embodiment. FIG. 6 is a block diagram of an excavator as an example of a work machine according to the embodiment.

  FIG. 1 is a block diagram of a power supply device mounted on a work machine according to an embodiment. A DC power supply 41 is connected to the input terminal Tin of the power supply device 50. For the DC power supply 41, for example, a lead storage battery is used.

  The power supply device 50 includes a switching circuit 43, a transformer 44, a first rectifier circuit 45, a booster circuit 46, a second rectifier circuit 47, and a control circuit 48. The transformer 44 includes a primary winding 44A, a first secondary winding 44B, and a second secondary winding 44C. The switching circuit 43 switches the current from the DC power supply 41 and supplies it to the primary winding 44 </ b> A of the transformer 44.

  The switching circuit 43 includes a switching element 43A connected in series to the primary winding 44A and a varistor diode 43B connected in parallel to the primary winding 44A. For example, an insulated gate bipolar transistor (IGBT) is used as the switching element 43A. The output voltage of the DC power supply 41 is applied to a series circuit of the primary winding 44A and the switching element 43A. The control circuit 48 controls on / off of the switching element 43A.

  By performing on / off control of the switching element 43A, the current flowing through the primary winding 44A is switched. The control circuit 48 controls the duty ratio of the pulsating flow that flows through the primary winding 44A. An AC voltage is generated in the first secondary winding 44B and the second secondary winding 44C in accordance with the duty ratio and winding ratio of the pulsating flow.

  The AC voltage appearing at the first secondary winding 44B is applied to the first rectifier circuit 45. The DC voltage rectified by the first rectifier circuit 45 is boosted by the booster circuit 46 and output to the first output terminal Tout1. The AC voltage appearing at the second secondary winding 44 </ b> C is rectified by the second rectifier circuit 47. The DC voltage rectified by the second rectifier circuit 47 is output to the second output terminal Tout2.

  The first output terminal Tout1 is connected to the power supply terminal of the sensor 55 that is an analog element, and the second output terminal Tout2 is connected to the power supply terminal of the control device 56 that is a digital element. That is, the first output terminal Tout1 generates a power supply voltage for an analog circuit, and the second output terminal Tout2 generates a power supply voltage for a digital circuit. The sensor 55 includes, for example, a hydraulic sensor that measures the hydraulic pressure of the high-pressure hydraulic line, a temperature sensor that measures the temperature of the pressurized oil, a temperature sensor that measures the outside air temperature, and the like. The control device 56 includes, for example, a central processing unit (CPU), a semiconductor memory, and the like.

  The power supply voltage for the digital circuit output to the second output terminal Tout2 is lower than the power supply voltage for the analog circuit output to the first output terminal Tout1. As an example, the output voltage v1 of the DC power supply 41 is 24V, the output voltage v2 of the first rectifier circuit 45 is 5V, and the output voltage v4 of the booster circuit 46, that is, the power supply voltage for the analog circuit is 12V. The output voltage v3 of the second rectifier circuit 47, that is, the power supply voltage for the digital circuit is 5V.

  The output voltage v3 of the second rectifier circuit 47 is input to the control circuit 48. The control circuit 48 controls the duty ratio of the pulsating current flowing in the primary winding 44A so that the output voltage v3 of the second rectifier circuit 47 becomes a target value, for example, 5V. Specifically, the time during which the switching element 43A is on is changed.

A cell motor 35 is connected to the DC power source 41 via a relay 36. By making the relay 36 conductive, DC power is supplied from the DC power supply 41 to the cell motor 35.

  FIG. 2 shows an equivalent circuit diagram of the booster circuit 46 (FIG. 1). Booster circuit 46 includes a reactor 46A, a switching element 46B, a diode 46C, and a smoothing capacitor 46D. A series circuit of the reactor 46 </ b> A and the switching element 46 </ b> B is connected between the output terminals of the first rectifier circuit 45. Reactor 46A is connected to the positive terminal of first rectifier circuit 45, and the emitter of switching element 46B is connected to the negative terminal.

  The interconnection point between the reactor 46A and the switching element 46B is connected to the positive terminal of the first output terminal Tout1 via the diode 46C. A forward current flows through the diode 46C from the reactor 46A toward the first output terminal Tout1. A smoothing capacitor 46D is connected between the positive terminal and the negative terminal of the first output terminal Tout1.

  When the control circuit 48 periodically turns on and off the switching element 46B, the output voltage of the rectifier circuit 45 is boosted and applied to the first output terminal Tout1.

  FIG. 3 shows an example of a temporal change in voltage of each part of the power supply device mounted on the work machine according to the embodiment. The horizontal axis represents elapsed time, and the vertical axis represents voltage. As an example, in a steady state, the output voltage v1 of the DC power supply 41 is 24V, the output voltage v2 of the first rectifier circuit 45, the output voltage v3 of the second rectifier circuit 47 is 5V, and the output voltage v4 of the booster circuit is 12V. It is. By making the number of turns of the first secondary winding 44B equal to the number of turns of the second secondary winding 44C, the output voltages v2 and v3 can be made equal.

  When the cell motor 35 (FIG. 1) is started at time t1, the discharge current from the DC power supply 41 increases and the voltage v1 temporarily decreases. For example, the voltage v1 decreases to about 10V. The control circuit 48 controls the switching circuit 43 so that the output voltage v3 of the second rectifier circuit 47 is maintained at the target value 5V. For this reason, even if the voltage applied to the primary winding 44A of the transformer 44 (FIG. 1) is reduced to about 10V, the output voltage v3 is maintained at the target value 5V. Since the number of turns of the first secondary winding 44V and the second secondary winding 44C is equal, the output voltage v2 of the first rectifier circuit 45 is also maintained at the target value 5V.

  Since the voltage applied to the booster circuit 46 (FIG. 1) is maintained at the target value 5V, the output voltage v4 is also maintained at the target value 12V.

  FIG. 4A shows a block diagram of a power supply device according to a comparative example. In the comparative example, the winding ratio between the primary winding 44A of the transformer 44 and the first secondary winding 44B is adjusted so that the output voltage v2 of the first rectifier circuit 45 becomes the target value 12V. . Since the output voltage v2 of the first rectifier circuit 45 is set to the target value 12V, the booster circuit 46 of the power supply device 50 mounted on the work machine according to the embodiment is unnecessary. The voltage v4 output to the first output terminal Tout1 is equal to the output voltage v2 of the first rectifier circuit 45.

  FIG. 4B shows an example of a temporal change in voltage of each part of the power supply device according to the comparative example. When the cell motor 35 (FIG. 4A) is activated at time t1, the voltage v1 temporarily decreases. A case where the voltage v1 decreases to 10V will be described. Since the control circuit 48 controls the switching circuit 43 so that the output voltage v3 of the second rectifier circuit 47 becomes the target value 5V, the output voltage v3 of the second rectifier circuit 47 is maintained at the target value 5V.

However, when the voltage applied to the primary winding 44A of the transformer 44 is reduced to 10V, the output of the first rectifier circuit 45 is obtained even if the switching circuit 43 controls the duty ratio of the pulsating current flowing through the primary winding 44A. The voltage v2 is a voltage of 10V applied to the primary winding 44A.
It cannot be maintained above. For this reason, the output voltage v2 of the first rectifier circuit 45 and the voltage v4 output to the first output terminal Tout1 are temporarily reduced to about 10V.

  In the embodiment, the target value of the output voltage v2 of the first rectifier circuit 45 is set to be lower than an assumed lower limit value of the output voltage v1 of the DC power supply 41, for example, 10V. The output voltage v2 of the circuit 45 can be maintained at the target value. By boosting the output voltage v2 maintained at the target value by the booster circuit 46, the voltage output to the first output terminal Tout1 can be maintained at the target value 12V.

  FIG. 5 shows a side view of an excavator as an example of the working machine according to the embodiment. An upper turning body 21 is mounted on the lower traveling body 20. A boom 23 is connected to the upper swing body 21, an arm 25 is connected to the boom 23, and a bucket 27 is connected to the arm 25. As the boom cylinder 24 expands and contracts, the posture of the boom 23 changes. As the arm cylinder 26 expands and contracts, the posture of the arm 25 changes. Due to the expansion and contraction of the bucket cylinder 28, the posture of the bucket 27 changes. The boom cylinder 24, the arm cylinder 26, and the bucket cylinder 28 are hydraulically driven.

  A swing motor 22, an engine 30, a motor generator 31, and a power supply device 50 are mounted on the upper swing body 21. As the power supply device 50, the power supply device 50 shown in FIG.

  FIG. 6 shows a block diagram of an excavator as an example of the working machine according to the embodiment. In FIG. 6, the mechanical power system is represented by a double line, the high-pressure hydraulic line is represented by a thick solid line, the electric control system is represented by a thin solid line, the power system is represented by a solid line of intermediate thickness, and the pilot line is represented by a broken line. Represent.

  The drive shaft of the engine 30 is connected to the input shaft of the torque transmission mechanism 32. The engine 30 is an engine that generates a driving force by a fuel other than electricity, for example, an internal combustion engine such as a diesel engine. The engine 30 is always driven during operation of the work machine.

  The drive shaft of the motor generator 31 is connected to the other input shaft of the torque transmission mechanism 32. The motor generator 31 can perform both the electric (assist) operation and the power generation operation. As the motor generator 31, for example, an internal magnet embedded (IPM) motor in which a magnet is embedded in the rotor is used.

  The torque transmission mechanism 32 has two input shafts and one output shaft. The output shaft is connected to the drive shaft of the main pump 75.

  When the load applied to the engine 30 is large, the motor generator 31 performs an assist operation, and the driving force of the motor generator 31 is transmitted to the main pump 75 via the torque transmission mechanism 32. Thereby, the load applied to the engine 30 is reduced. On the other hand, when the load applied to the engine 30 is small, the driving force of the engine 30 is transmitted to the motor generator 31 via the torque transmission mechanism 32, so that the motor generator 31 is operated for power generation.

  Three-phase AC wiring 60 connects the inverter 51 and the motor generator 31. A DC wiring (bus line) 61 connects the inverter 51 and the storage circuit 40. A three-phase AC wiring 62 connects the turning electric motor 22 and the inverter 52. A DC wiring (bus line) 63 connects the inverter 52 and the storage circuit 40. Inverters 51 and 52 and power storage circuit 40 are controlled by control device 56. As shown in FIG. 1, the control device 56 is supplied with power from the power supply device 50.

The inverter 51 controls the operation of the motor generator 31 based on a command from the control device 56. Switching between the assist operation and the power generation operation of the motor generator 31 is performed by the inverter 51.

  During the period in which the motor generator 31 is assisted, necessary power is supplied from the power storage circuit 40 to the motor generator 31 through the inverter 51. During the period in which the motor generator 31 is generating, the electric power generated by the motor generator 31 is supplied to the storage circuit 40 through the inverter 51.

A cell motor 35 is connected to the power supply device 50 via a relay 36. The power storage circuit 40 includes a power storage device such as a lithium ion capacitor, an electric double layer capacitor, or a lithium ion secondary battery, and a step-up / down converter that controls charging / discharging of the power storage device.

  The swing electric motor 22 is AC driven by the inverter 52 and can perform both the power running operation and the regenerative operation. For example, an IPM motor is used for the swing motor 22. During the power running operation of the swing motor 22, electric power is supplied from the power storage circuit 40 to the swing motor 22 via the inverter 52. The turning electric motor 22 turns the upper turning body 21 (FIG. 1) via the speed reducer 80. During regenerative operation, the rotational motion of the upper swing body 21 is transmitted to the swing electric motor 22 via the speed reducer 80, so that the swing electric motor 22 generates regenerative power. The generated regenerative power is supplied to the storage circuit 40 via the inverter 52. Thereby, the power storage device (DC power source shown in FIG. 1) in the power storage circuit 40 is charged.

  The resolver 81 detects the position of the rotating shaft of the turning electric motor 22 in the rotational direction. The detection result of the resolver 81 is input to the control device 56. By detecting the position of the rotating shaft in the rotational direction before and after the operation of the turning electric motor 22, the turning angle and the turning direction are derived.

  A mechanical brake 82 is connected to the rotating shaft of the turning electric motor 22 and generates a mechanical braking force. The braking state and the release state of the mechanical brake 82 are controlled by the control device 56 and switched by an electromagnetic switch.

  The main pump 75 supplies hydraulic pressure to the control valve 77 via the high pressure hydraulic line 76. The control valve 77 distributes hydraulic pressure to the hydraulic motors 29A and 29B, the boom cylinder 24, the arm cylinder 26, and the bucket cylinder 28 in accordance with a command from the driver. The hydraulic motors 29A and 29B drive the two left and right crawlers provided in the lower traveling body 20 shown in FIG.

  The pilot pump 78 generates a pilot pressure necessary for the hydraulic operation system. The generated pilot pressure is supplied to the operating device 83 via the pilot line 79. The operation device 83 includes a lever and a pedal and is operated by a driver. The operating device 83 converts the primary side hydraulic pressure supplied from the pilot line 79 into a secondary side hydraulic pressure in accordance with the operation of the driver. The secondary side hydraulic pressure is transmitted to the control valve 77 via the hydraulic line 84 and to the pressure sensor 86 via the other hydraulic line 85.

  The pressure detection result detected by the pressure sensor 86 is input to the control device 56. Thereby, the control apparatus 56 can detect the operating condition of the lower traveling body 20, the turning electric motor 22, the boom 23, the arm 25, and the bucket 27 (FIG. 1).

  Detection results from the plurality of sensors 55 are input to the control device 56. As shown in FIG. 1, the sensor 55 is supplied with power from the power supply device 50.

When the power supply device according to the comparative example shown in FIG. 4A is adopted, when the cell motor 35 is started, the voltage v4 (FIG. 4A, FIG. 4B) of the DC power supplied to the sensor 55 is lower than the rated value. Become. On the other hand, the voltage v3 (FIGS. 4A and 4B) of the DC power source supplied to the control device 56 is maintained at the rated value. Although the control device 56 operates normally, since the normality of the measurement result from the sensor 55 is not guaranteed, the measurement result of the sensor 55 may show an abnormal value.

  The control device 56 detects the abnormal value measured due to the temporary drop in the power supply voltage within a certain time from the start of the cell motor 35 so as not to erroneously determine that the abnormal value is an abnormal value of the physical quantity to be measured. The process of ignoring the abnormal value of the detected sensor is performed. For this reason, even if a true abnormality occurs within a period in which the abnormal value is ignored, the abnormality cannot be detected.

  When the power supply device 50 shown in FIG. 1 is adopted as the power supply device 50 (FIG. 6), as shown in FIG. 3, the voltage of the DC power supply supplied to the sensor 55 even when the cell motor 35 (FIG. 6) is started. Is maintained at almost the rated value. For this reason, it is possible to detect an abnormality by the sensor 55 even when the cell motor 35 is started.

  In the above-described embodiment, an excavator is shown as an example of a work machine on which the power supply device 50 is mounted. However, the power supply device 50 described above may be used in other work machines such as a cargo handling work vehicle (forklift), a bulldozer, and a crane. Is also applicable.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF SYMBOLS 20 Lower traveling body 21 Upper revolving body 22 Turning electric motor 23 Boom 24 Boom cylinder 25 Arm 26 Arm cylinder 27 Bucket 28 Bucket cylinder 29A, 29B Hydraulic motor 30 Engine 31 Motor generator 32 Torque transmission mechanism 35 Cell motor 36 Relay 40 Power storage circuit 41 DC Power supply 43 Switching circuit 43A Switching element 43B Varistor diode 44 Transformer 44A Primary winding 44B First secondary winding 44C Second secondary winding 45 First rectifier circuit 46 Booster circuit 46A Reactor 46B Switching element 46C Diode 46D Smoothing Capacitor 47 Second rectifier circuit 48 Control circuit 50 Power supply device 51, 52 Inverter 55 Sensor 56 Control device 60, 62 Three-phase AC wiring 61, 63 DC wiring 75 Main pump 76 High-pressure hydraulic line 77 Control valve 78 Pilot pump 79 Pilot line 80 Reducer 81 Resolver 82 Mechanical brake 83 Operating device 84, 85 Hydraulic line 86 Pressure sensor

Claims (4)

DC power supply,
A transformer including a primary winding and a first secondary winding;
A switching circuit that switches current from the DC power source and applies the current to the primary winding of the transformer;
A first rectifier circuit for rectifying alternating current appearing in the first secondary winding;
A booster circuit for boosting the output of the first rectifier circuit and generating a power supply voltage for an analog circuit ;
A cell motor connected to the DC power source;
An engine activated by the cell motor;
Having working machine. The work machine according to claim 1, further comprising a sensor that is connected to an output terminal of the booster circuit and measures oil pressure or temperature. (Claiming claim 2 down)
The transformer further includes a second secondary winding,
3. The second rectifier circuit according to claim 2 , further comprising a second rectifier circuit that rectifies an alternating current appearing in the second secondary winding to generate a power supply voltage for a digital circuit lower than the power supply voltage for the analog circuit. Work machine. The work machine according to claim 3, further comprising a control device that is connected to an output terminal of the second rectifier circuit, receives a detection result of the sensor, and detects an abnormality based on the input detection result.

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