JP2013257211A - Work vehicle and its electric leakage detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a work vehicle and its electric leakage detection method that can determine electric leakage with high precision through simple circuit constitution.SOLUTION: A work vehicle includes an electric leakage detection part 5 which detects electric leakage of a capacitor 2; a circuit changeover switch which disconnected the capacitor 2 from a load circuit 1 and connects the electric leakage detection part 5 to the capacitor 2, and disconnects the electric leakage detection part 5 from the capacitor 2 and connects the capacitor 2 to the load circuit 1; and a microcomputer 6 which places the circuit changeover switch SW in operation to disconnect the capacitor 2 from the load circuit 1 and to connect the electric leakage detection part 5 to the capacitor 2 on detecting the capacitor 2 being fully charged and also detecting no current flowing to the load circuit 1, and also places the circuit changeover switch to disconnect the electric leakage detection part 5 from the capacitor 2 and to connect the capacitor 2 to the load circuit 1 after the electric leakage detection part 5 detects electric leakage of the capacitor 2.

Description

  The present invention relates to a work vehicle having a load circuit driven by electric power stored in a power storage device and a method for detecting leakage of the work vehicle.

  Conventionally, an electric system using a power storage device has been widely used in various work vehicles such as a battery forklift, a hybrid power shovel, an electric aerial work vehicle, a hybrid crane, and a railway vehicle. For example, in the mixer truck described in Patent Document 1, a generator driven by an engine, a power storage device that stores the output of the power generator, and an electric drive device that includes a motor that is driven by the power stored in the power storage device; The drum is rotated by an electric drive device.

  By the way, in this type of work vehicle, the voltage of the power storage device is higher than that of a lead battery mounted on a normal gasoline engine. Therefore, a work vehicle equipped with a high-voltage power storage device is equipped with a leakage detection device that automatically detects leakage. For example, in Patent Document 2, a leakage detection resistor provided between a terminal of a battery for traveling and the body of an electric vehicle, a means for monitoring a terminal voltage of the leakage detection resistor, and a value of the terminal voltage are disclosed. There is disclosed an electric vehicle leakage detection device including means for comparing whether or not a predetermined value or more and means for notifying a maintenance instruction when the value of the terminal resistance exceeds a predetermined value.

JP 2003-226192 A Japanese Utility Model Publication No. 6-2901

  However, in the case of a work vehicle that operates an electric system with electric power stored in the power storage device, the voltage of the power storage device changes according to the amount of discharge by driving the electric system and the amount of charge to the power storage device by a generator. Therefore, it is difficult to detect leakage by simply monitoring the voltage change, and the circuit for detecting leakage becomes complicated.

  Therefore, an object of the present invention is to provide a work vehicle and a leakage detection method thereof that can determine leakage with high accuracy with a simple circuit configuration.

  A work vehicle according to the present invention is a work vehicle having a load circuit driven by electric power, a power storage device that stores power supplied to the load circuit, and a charging circuit that charges the power storage device, and detecting leakage of the power storage device An earth leakage detection unit that disconnects the electricity storage device from the load circuit, connects the electricity leakage detection unit to the electricity storage device, disconnects the electricity leakage detection unit from the electricity storage device, and connects the electricity storage device to the load circuit; When it is detected that the device is fully charged and the current of the load circuit is zero, the circuit changeover switch is operated to disconnect the power storage device from the load circuit, and a leakage detector is connected to the power storage device. After connecting and detecting the leakage of the power storage device by the leakage detection unit, the circuit changeover switch is operated to disconnect the leakage detection unit from the storage device and load the storage device. In which a control unit to be connected to.

  The work vehicle leakage detection method of the present invention is a work vehicle leakage detection method including a load circuit driven by electric power, a power storage device that stores power supplied to the load circuit, and a charging circuit that charges the power storage device. And detecting the leakage of the power storage device by disconnecting the power storage device from the load circuit when it is detected that the power storage device is fully charged and the current of the load circuit is zero. The method includes reconnecting the power storage device to the load circuit after detecting leakage of the device.

  According to these inventions, when it is detected that the power storage device is fully charged and the current of the load circuit is detected as zero, the power storage device is disconnected from the load circuit and the leakage of the power storage device is detected. After the detection is performed and the leakage detection of the power storage device is performed, the power storage device is reconnected to the load circuit. Thus, in these inventions, since leakage detection is performed in a state where the power storage device is disconnected from the load circuit, highly accurate determination is possible.

  In the work vehicle of the present invention, it is preferable that the control unit operates the circuit changeover switch every time the engine key-on signal of the work vehicle is detected, and causes the leakage detection unit to detect the leakage of the power storage device. As a result, one leakage detection is performed for one engine start of the work vehicle.

  Moreover, it is desirable that the leakage detection unit is configured to detect leakage from a change in voltage of the power storage device when the resistance value between the power storage circuit and the chassis of the work vehicle is switched once. As a result, when an electrical leakage occurs between the power storage circuit and the chassis of the work vehicle, the change in the voltage of the power storage device is reduced before and after switching of the resistance value between the power storage device and the chassis of the work vehicle. It is possible to easily detect leakage.

(1) When it is detected that the power storage device is fully charged and the current of the load circuit is detected to be zero, the power storage device is disconnected from the load circuit and the leakage detection of the power storage device is performed. After the detection of leakage of the power storage device, the voltage changes depending on the amount of charge / discharge due to the configuration in which the power storage device is reconnected to the load circuit. It becomes possible to determine with high accuracy with a simple circuit configuration.

(2) By detecting the leakage of the power storage device every time the engine key-on signal of the work vehicle is detected, one leakage detection is performed for one engine start of the work vehicle. A leak is detected.

(3) A leakage current is detected between the storage circuit and the chassis of the work vehicle by a configuration in which leakage detection is performed from a change in the voltage of the storage device when the resistance value between the storage circuit and the chassis of the work vehicle is switched once. When this occurs, the change in the voltage of the power storage device becomes small before and after the resistance value is switched between the power storage device and the chassis of the work vehicle, so that the leakage detection can be easily performed.

It is a schematic block diagram which shows a part of electric circuit of the garbage truck as a working vehicle in embodiment of this invention. It is an operation | movement flowchart of the main process of the control part of FIG. It is an operation | movement flowchart of the electric leakage detection process of FIG.

  FIG. 1 is a schematic configuration diagram showing a part of an electric circuit of a garbage truck as a work vehicle according to an embodiment of the present invention. In FIG. 1, a garbage truck as a work vehicle in an embodiment of the present invention includes a load circuit 1 driven by electric power, a capacitor 2 as a power storage device that stores electric power supplied to the load circuit 1, and a capacitor 2. A charging circuit 3 for charging and a leakage detection circuit 4 for detecting leakage of the capacitor 2 are provided.

  Although the details of the garbage truck in this embodiment are not shown, a dust container box provided at the rear of the cab and a dust container box provided at the rear of the dust container box, as in a normal garbage truck, It has. In the dust input box, there is mounted a dust loading device as a working device composed of a dust pushing plate, a rotating plate, a discharge plate, etc. for loading the dust thrown into the dust containing box into the dust containing box. Yes. The dust loading device is driven by a hydraulic cylinder and a hydraulic motor that are driven by pressure oil generated by a hydraulic pump.

  The load circuit 1 is, for example, an electric motor that drives the hydraulic pump. A permanent magnet synchronous electric motor is adopted as the electric motor. Since this permanent magnet synchronous electric motor is vector-controlled, the size and mass are reduced and the efficiency is extremely high compared to a conventional induction motor, so that the electric energy stored in the capacitor 2 can be used efficiently. It has the characteristics.

  The capacitor 2 is an electric double layer capacitor (so-called capacitor), and utilizes a physical phenomenon that does not use a chemical reaction and simply stores electric charges unlike a battery. Since the electric double layer capacitor has a very long life and can be charged with a large current, the charging time is very short and it is relatively inexpensive. The capacitor 2 of the present embodiment is composed of a plurality of units, and is disposed in an equipment storage box provided between the cab and the dust storage box and on the side (not shown) of the chassis, and is electrically connected. Are connected in series. Thereby, voltage output of several hundred volts is possible in total.

  Although not shown in detail, the charging circuit 3 includes a generator that generates electricity using a vehicle travel engine as a vehicle travel drive source, and an AVR (automatic voltage control device). The generator is installed separately from a small power generator (dynamo) normally mounted on a vehicle, and is always driven by a fan belt (not shown) while the vehicle traveling engine is driven. The generator may be driven only when necessary. AVR converts the AC power of the generator into DC, and adjusts the output voltage of the generator to be a constant target value regardless of changes in the rotational speed of the vehicle travel engine. That is, the voltage exceeding the predetermined voltage is not supplied to the capacitor 2 by the voltage upper limit control function of the AVR.

  The leakage detection circuit 4 includes resistors R1 to R4, Rp, a relay Ry, and the like, and detects a leakage current detection unit 5 that detects leakage of the capacitor 2, a circuit changeover switch SW, and a current that flows from the capacitor 2 to the load circuit 1. And a microcontroller (hereinafter referred to as “microcomputer”) 6 as a control unit. In the microcomputer 6, the leakage detector 5 is input as the analog input 1, and the current sensor I is input as the analog input 2. Further, the engine key-on signal of the work vehicle is inputted as the digital input 1 to the microcomputer 6. The microcomputer 6 outputs a control signal for the circuit changeover switch SW as the digital output 1 and a control signal for the relay Ry as the digital output 2 based on the inputs from the analog inputs 1 and 2 and the digital input 1.

  The circuit selector switch SW is provided between the load circuit 1, the capacitor 2, the leakage detection unit 5, and the analog input 1 of the microcomputer 6. When the circuit selector switch SW is switched to the contact a, the positive and negative electrodes of the capacitor 2 are connected to the load circuit 1, and the positive and negative electrodes of the capacitor 2 are connected to the analog input 1 of the microcomputer 6. On the other hand, when the circuit changeover switch SW is switched to the contact point b, the positive and negative electrodes of the load circuit 1 are disconnected from the capacitor 2, and the positive and negative electrodes of the capacitor 2 are connected to the leakage detecting unit 5, and the leakage detecting unit 5 is connected to the microcomputer. 6 analog inputs 1 are connected.

  Capacitor 2 is electrically floating from the chassis of the work vehicle, and resistances connected to the chassis are leakage resistances Rop and Ron. The voltage of the capacitor 2 is divided by the resistors R1, R2, and R3, and the voltage across the resistor R2 is further divided by the resistor R4 and the input resistor Rin of the analog input 1 of the microcomputer 6 and input to the analog input 1. Is done. One side of the resistor R2 is connected to the chassis. When the relay Ry is turned on, the resistor Rp is connected between the positive electrode of the capacitor 2 and the chassis.

  Here, the input voltage of the analog input 1 when the relay Ry is off is V1, and the input voltage when the relay Ry is on is V2. When the relay Ry is turned on, the resistor Rp is in parallel with the resistors R1 and R2, so that V1> V2. At this time, V1−V2 = V3. When the positive electrode of the capacitor 2 is leaked, the leakage resistance Rop is always connected to the positive electrode of the capacitor 2, so that changes in the input voltages V1 and V2 when the relay Ry is turned off are small, and V3 is small. In other words, the leakage resistance Rop can be measured by measuring V3. Similarly, when the negative electrode of the capacitor 2 is leaked, the leakage resistance Ron can be measured by measuring V3.

  Next, the operation of the microcomputer 6 will be described with reference to FIGS. FIG. 2 is an operation flowchart of main processing of the microcomputer 6 of FIG. 1, and FIG. 3 is a flowchart of leakage detection processing of FIG.

  As shown in FIG. 2, the microcomputer 6 first controls the switch SW by the digital output 1 to switch to the contact a side, disconnects the capacitor 2 from the leakage detector 5 and connects the capacitor 2 to the load circuit 1 (step). S101). Next, the microcomputer 6 detects engine start-up by inputting an engine key-on signal to the digital input 1 (step S102), and then detects that the capacitor 2 is fully charged by the analog input 1 (step S103). When the analog input 2 detects that the current of the load circuit 1 is zero (step S104), the switch SW is controlled by the digital output 1 to switch to the contact b side, and the capacitor 2 is disconnected from the load circuit 1. The leakage detection unit 5 is connected to the capacitor 2 (step S105), and the leakage detection process is started (step S106).

  When the leakage detection process is started, as shown in FIG. 3, the microcomputer 6 first turns off the relay Ry (step S110) and measures the input voltage V1 of the analog input 1 (step S111). Next, the microcomputer 6 turns on the relay Ry (step S112), and measures the input voltage V2 of the analog input 1 (step S113). Next, the microcomputer 6 turns off the relay Ry (step S114). If V1 / V2 is equal to or less than the determination reference value, the microcomputer 6 determines that the current is leaking (step S115), and starts the leakage process (step S116). . On the other hand, if it is equal to or greater than the reference value, it returns to the main as normal and waits for the start of leakage detection processing (step S117).

  After normal processing, returning to FIG. 2, the microcomputer 6 controls the switch SW with the digital output 1 to switch to the contact a side, disconnects the capacitor 2 from the leakage detector 5, and reconnects the capacitor 2 to the load circuit 1. (Step S107), the next engine start is awaited (Step S102). That is, the microcomputer 6 performs one leakage detection for one engine start.

  As described above, in the garbage truck in the present embodiment, when it is detected that the capacitor 2 is fully charged and the current of the load circuit 1 is detected to be zero, the capacitor 2 is connected to the load circuit 1. Is disconnected from the capacitor 2 and the leakage of the capacitor 2 is detected. After the leakage of the capacitor 2 is detected, the capacitor 2 is reconnected to the load circuit 1. Therefore, since the voltage changes depending on the charge / discharge amount, it is possible to determine the leakage of the capacitor 2 that cannot be accurately measured during charge / discharge with high accuracy with a simple circuit configuration.

  Moreover, in the garbage truck in this embodiment, since the leak detection of the capacitor 2 is detected every time when the engine key-on signal of the work vehicle is detected, one leak detection is performed for one engine start of the work vehicle. The leakage of the capacitor 2 is detected with frequency.

  Moreover, in the garbage truck in this embodiment, since the resistance value between the capacitor 2 and the chassis of the work vehicle is detected once by changing the voltage of the capacitor 2 when the resistance value between the capacitor 2 and the chassis of the work vehicle is switched once by turning on / off the relay Ry, When a leakage occurs between the motor 2 and the chassis of the work vehicle, the change in the voltage of the capacitor 2 becomes small before and after the resistance value is switched between the capacitor 2 and the chassis of the work vehicle. It is possible to do it.

  INDUSTRIAL APPLICABILITY The present invention is useful as a work vehicle having a load circuit that is driven by electric power stored in a power storage device and a method for detecting leakage of the work vehicle.

DESCRIPTION OF SYMBOLS 1 Load circuit 2 Capacitor 3 Charging circuit 4 Earth leakage detection circuit 5 Earth leakage detection part 6 Microcontroller (microcomputer)

Claims (6)

A load circuit driven by electric power;
A power storage device for storing electric power to be supplied to the load circuit;
A work vehicle having a charging circuit for charging the power storage device,
A leakage detection unit for detecting leakage of the power storage device;
Disconnecting the power storage device from the load circuit and connecting the leakage detector to the power storage device; and disconnecting the leakage detector from the power storage device and connecting the power storage device to the load circuit;
When detecting that the power storage device is fully charged and detecting that the current of the load circuit is zero, the circuit changeover switch is operated to disconnect the power storage device from the load circuit and The leakage detection unit is connected to a power storage device, and after the leakage detection unit detects the leakage of the power storage device, the circuit changeover switch is operated to disconnect the leakage detection unit from the power storage device and to connect the power storage device. A work vehicle having a control unit connected to the load circuit.   2. The work vehicle according to claim 1, wherein the control unit operates the circuit changeover switch each time an engine key-on signal of the work vehicle is detected, and causes the leakage detection unit to detect leakage of the power storage device.   The leakage detection unit detects leakage from a change in voltage of the power storage device when a resistance value between the power storage circuit and the chassis of the work vehicle is switched once. Work vehicle. A load circuit driven by electric power;
A power storage device for storing electric power to be supplied to the load circuit;
A leakage detection method for a work vehicle having a charging circuit for charging the power storage device,
When detecting that the power storage device is fully charged and detecting that the current of the load circuit is zero, disconnecting the power storage device from the load circuit and detecting leakage of the power storage device ,
An electrical leakage detection method for a work vehicle, comprising: connecting the electrical storage device to the load circuit after performing electrical leakage detection of the electrical storage device.   5. The work vehicle leakage detection method according to claim 4, wherein the leakage detection of the power storage device is performed each time an engine key-on signal of the work vehicle is detected.   6. The leakage detection of the power storage device is performed from a change in voltage of the power storage device when a resistance value between the power storage circuit and the vehicle chassis is switched once. Method for detecting electric leakage in work vehicles.

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