Method for controlling a system consisting of an industrial truck and a charger

Abstract

Method for controlling a system comprising an industrial truck and a charging device (8), wherein the industrial truck has a battery receptacle for a traction battery and a fan (21) for the battery receptacle, which fan is driven by a fan electric motor (16), and the separate charging device (8) for the traction battery has a control device and a charging cable with a plug connection via which the charging device (8) can be connected to the traction battery, wherein at least one signal line (26, 27, 28) can be connected to the fan electric motor (16) via an auxiliary plug connection (29), characterized in that the control device of the charging device (8) checks, in a first step, via the at least one signal line (26, 27, 28), whether the fan (21) is detected as being stationary, in a second step starts the fan (21), and in a third step, if the fan (21) is detected as being running, starts the charging process.

Description

[0001] The invention relates to a method for controlling a system comprising an industrial truck and a charging device, wherein the industrial truck has a battery holder for a traction battery and a fan for the battery holder, which fan is driven by a fan electric motor, and the separate charging device for the traction battery has a control device and a charging cable with a plug connection via which the charging device can be connected to the traction battery, wherein at least one signal line can be connected to the fan electric motor via an auxiliary plug connection.

[0002] From the subsequently published DE 10 2013 103 414 A1, a system comprising an industrial truck and a charging device is known, wherein the industrial truck has a battery holder for a traction battery and a fan for the battery holder, which fan is driven by a fan electric motor, and the separate charging device for the traction battery has a control device and a charging cable with a plug connection, via which the charging device can be connected to the traction battery, wherein at least one signal line can be connected to the fan electric motor via an auxiliary plug connection.

[0003] From DE 20 2008 006 635 U1 an industrial truck with a battery unit is known, wherein in the area of a connection port of the battery unit with a charger a sensor is provided which senses a connected charger, and the battery unit has a fan which is operated when the sensor has sensed the connected charger.

[0004] A secondary battery unit of an electric vehicle is known from JP H11 - 252 808 A.

[0005] From JP 2002 - 191 103 A a driverless transport vehicle and a charging method for the battery of the transport vehicle are known.

[0006] For battery-electric industrial trucks, such as reach trucks or battery-electric counterbalance forklifts, a high degree of operational flexibility is desired. To achieve this, it is known that, in addition to the option of replacing a discharged traction battery with a charged one, a charging option for the traction battery remaining in the vehicle is also required. This eliminates the need for a fixed charging station and the associated costs if the industrial trucks are only used occasionally or only in single-shift operations. In addition to chargers permanently integrated into the vehicle, dedicated, separate chargers are also available that can be used for a variety of vehicles.

[0007] Lead-acid batteries are predominantly used as traction batteries. When charging a lead-acid battery in an industrial truck, adequate ventilation must be ensured, as hydrogen gases are generated during charging, which, when combined with the air in a closed enclosure, could form an explosive mixture. If the required ventilation of a battery compartment cannot be safely ensured by opening a door or hood, forced ventilation or extraction of the resulting gases in the battery compartment must be provided.

[0008] One known solution for this is to install an electric fan. This is often located near the rear of the industrial truck, for example, in electric counterbalance forklifts, where a battery holder formed by a battery compartment is located under a driver's seat in front of a counterweight. For safety reasons, it is required that the battery charger and the electric fan operate in a mutually interlocked state. This means that if the fan fails, the charging current must be automatically interrupted, or the fan must always operate when the battery charger is generating a charging current.

[0009] One known solution involves connecting the electric motor that drives the fan via a voltage converter. A monitoring logic for the fan sends a signal that, via a relay, energizes a contactor located in the battery charger's connecting cable. This ensures that the fan runs while the battery is charging.

[0010] A disadvantage of this state of the art technology is that discrete components must be provided for this purpose in the vehicle, which requires corresponding space and costs. In the event of a fault, there is also no protection against the fan restarting. If, for example, the fan becomes mechanically blocked, the contactor would shut off battery charging. However, if the fan does start up again, the battery charging could continue. The state of the art solution therefore does not de-energize the fan or the contactor in the event of a fault. Furthermore, incorrectly sticking contacts of the contactor or the fan electric motor cannot be detected. Finally, it is not possible for the fan to continue running after an emergency stop switch has been activated; with an alternative circuit, the fan always runs when the emergency stop is activated.

[0011] The present invention is based on the object of providing a method for operating a system comprising an industrial truck and a charging device, which avoids the above-mentioned disadvantages and with which operation of the battery fan during charging can be ensured.

[0012] This object is achieved by a method having the features of patent claim 1. Advantageous further developments are specified in the subclaims.

[0013] The object is achieved by a method for controlling a system comprising an industrial truck and a charging device, wherein the industrial truck has a battery holder for a traction battery and a fan for the battery holder, which fan is driven by a fan electric motor, and the separate charging device for the traction battery has a control device and a charging cable with a plug connection via which the charging device can be connected to the traction battery, wherein at least one signal line can be connected to the fan electric motor via an auxiliary plug connection, wherein the control device of the charging device checks in a first step via the at least one signal line whether the fan is detected as being stationary, starts the fan in a second step and, if the fan is detected as being running, starts the charging process in a third step.

[0014] This advantageously allows you to first test the functionality of the fan monitoring system itself. For example, it can detect if the contacts of a mechanical relay that controls the fan are sticking. In any case, however, the charger ensures that charging of the traction battery only begins when the fan is running.

[0015] In the method, the control device advantageously detects the function of the fan based on the monitoring signal.

[0016] If the fan is detected as being stopped during the charging process, the charging process can be aborted.

[0017] In a further development of the method, after the charging of the traction battery has been completed, the control device continues to operate the fan for a follow-up period.

[0018] Even after the traction battery has been charged, battery gases are still produced, which can be extracted by the fan running afterward.

[0019] In one embodiment of the method, after an interruption in charging the traction battery due to a stopped fan, the traction battery is not automatically restarted and charged.

[0020] Therefore, if charging of the traction battery is interrupted due to a monitoring signal indicating a malfunction of the fan, restarting the fan and continuing charging of the traction battery is only possible after deliberately resetting the charger or restarting it. In particular, an error message can also be generated, and the requirement for a reset ensures that this error message is acknowledged.

[0021] In the system according to the invention comprising an industrial truck and a charging device, wherein the industrial truck has a battery holder for a traction battery and a fan for the battery holder, which fan is driven by a fan electric motor, and the separate charging device for the traction battery has a control device and a charging cable with a plug connection via which the charging device can be connected to the traction battery, at least one signal line is connected to the fan electric motor via an auxiliary plug connection.

[0022] This advantageously eliminates the need for discrete components, while still ensuring that the fan is functioning properly even with an external charger. The signal line can be used as a dedicated signal line, transmitting a monitoring signal about the fan's status. This can be done, for example, by control electronics that emits such a monitoring signal and is connected to or integrated into the fan's electric motor. It is also conceivable for the signal line to provide a supply voltage to the fan's electric motor using known methods, and to monitor the fan's electric motor's behavior, in particular whether it is running or not, based on current and voltage.

[0023] A monitoring electronics of the fan electric motor can send a monitoring signal for the function of the fan to the control device of the charger via a signal line.

[0024] Cost-effective and reliable electronic components are available as monitoring electronics that emit a signal as long as the fan motor is actually rotating. This signal can be transmitted to the charger via a dedicated signal line.

[0025] In an advantageous further development, the charger supplies a supply voltage for the fan electric motor via a signal line.

[0026] If the fan electric motor does not require its supply voltage from the industrial truck, the industrial truck may be without power during charging.

[0027] The charger can provide a ground connection for the fan electric motor via a signal line.

[0028] If there is also a ground connection to the charger via another signal line, it is possible to completely electrically separate the traction battery from the industrial truck during charging and still ensure that the fan functions and thus the necessary ventilation of the battery holder.

[0029] It is conceivable, in principle, to have only a single signal line for a monitoring signal. Alternatively, a combination of a power supply and the monitoring signal can be transmitted to the charger via two signal lines, or three signal lines can transmit the complete power supply, including ground, and a monitoring signal.

[0030] Further advantages and details of the invention are explained in more detail with reference to the embodiment shown in the schematic figures. Fig. 1 schematically shows the control circuit for a ventilation of a battery holder according to the prior art, Fig. 2 schematically shows the installation situation of a fan and Fig. 3 schematically shows the circuit of a system according to the invention comprising an industrial truck and a charger.

[0031] The Fig. 1 schematically shows the circuit of a control device 1 of a prior art industrial truck (not shown) for ventilating a battery receptacle. An emergency stop switch 4 is connected to the positive terminal 2 of a traction battery 3 in a battery receptacle (not shown). A charging relay 5, which may be configured as a contactor 6, connects the emergency stop switch 4 to a positive contact 7 of a charger 8, which is connected via a negative contact 9 to a ground 10 or a negative terminal 11 of the traction battery 3. A voltage converter 13, protected by a fuse 12, can supply voltage to a fan motor 16 via a connection using pilot contacts 14 and a wire bridge 15 in a charger connector. Monitoring electronics 17, which emits a negative signal when the fan motor 16 is running and thus functioning, switches an electromagnet 18 of a monitoring relay 19.The monitoring relay 19 switches an electromagnet 20 of the charging switching relay 5.

[0032] When the emergency stop switch 4 is pressed, the positive voltage of the traction battery 3 is applied to the charging relay 5 or contactor 6. The voltage converter 13 then starts the electric fan motor 16 via the pilot contacts 14 and the wire bridge 15. When the electric fan motor 16 is operating properly, thus providing ventilation to the industrial truck's battery compartment, the monitoring electronics 17 of the electric fan motor 16 emits a negative signal, which energizes the electromagnet 18 of the monitoring relay 19. This energizes the electromagnet 20 of the charging relay 5, and a charging current can charge the traction battery 3 via the positive contact 7 of the charging current plug 8. If the charging plug is pulled out, the electric fan motor 16 is switched off because the wire bridge 15 is interrupted.Likewise, the charging current is switched off if the monitoring electronics 17 does not emit a signal, for example because the fan electric motor 16 is stopped due to a blockage of the fan.

[0033] A disadvantage of this prior art is that there is no safeguard against the fan restarting in the event of a fault. For example, after the fan has become blocked, as soon as this blockage is released, the monitoring electronics 17 again emits a control signal that closes the charging relay 5 via the electromagnet 18, thus continuing charging. The voltage is not disconnected. Sticky or stuck contacts of the fan's electric motor 16 cannot be detected. Furthermore, the fan cannot continue to run after an emergency shutdown or unplugging the charging connector 8.

[0034] The Fig. Figure 2 schematically shows the installation situation of a fan 21. The fan 21 with the fan electric motor 16 is permanently installed in the industrial truck, in this example a counterbalance forklift, under a cover (not shown but open in the cutout). This allows the fan 21 to extract gases generated from the battery receptacle. A charger plug 25 is located next to the fan 21.

[0035] The Fig. Figure 3 shows schematically the circuit of a system according to the invention comprising an industrial truck and the charger 8. The charger 8 is connected via a positive contact 7 and a negative contact 9, both of which are located in the Fig. 2, are connected to the industrial truck (not shown). The fan electric motor 16 of the fan 21 from the Fig.2, which is permanently integrated into the industrial truck, also has monitoring electronics 17. The fan electric motor 16 is supplied with a supply voltage via a first signal line 26. Ground is applied to a second signal line 27, and the signal from the monitoring electronics 17 is fed to a control device of the charger 8 via a third signal line 28. All three signal lines 26, 27, 28 can be connected to the charger 8 via the auxiliary plug connection 29. The auxiliary plug connections 29 can be provided in a separate plug connection or possibly integrated as separate contacts in the charger plug 25. In the latter case, it is conceivable to ensure, by means of a mechanically shaped charger plug 25, that operation is only possible with a charger 8 that is equipped according to the invention.

[0036] Advantageously, the external charger 8 can monitor the functionality of the fan 21 or the fan electric motor 16. Sticky contacts of the fan electric motor 16 can also be detected, and the control device of the charger 8 can cause the fan electric motor 16 to continue running after a traction battery has been successfully charged.

Claims

[1] Method for controlling a system comprising an industrial truck and a charging device (8), wherein the industrial truck has a battery holder for a traction battery and a fan (21) for the battery holder, which fan is driven by a fan electric motor (16), and the separate charging device (8) for the traction battery has a control device and a charging cable with a plug connection, via which the charging device (8) can be connected to the traction battery, wherein at least one signal line (26, 27, 28) can be connected to the fan electric motor (16) via an auxiliary plug connection (29), characterized by that the control device of the charger (8) checks in a first step via the at least one signal line (26, 27, 28) whether the fan (21) is detected as being stationary, in a second step starts the fan (21) and in a third step, if the fan (21) is detected as being running, starts the charging process. [2] Method according to claim 1 in a system in which a monitoring electronics unit (17) of the fan electric motor (16) outputs a monitoring signal for the function of the fan (21) via the signal line (28) to the control device of the charger (8), characterized by that the control device detects the function of the fan (21) based on the monitoring signal. [3] Method according to claim 1 or 2, characterized by that during the charging process, if the fan (21) is detected as being stationary, the charging operation is aborted. [4] Method according to one of claims 1 to 3, characterized by that after the charging of the traction battery has been completed, the control device continues to operate the fan (21) for a follow-up period. [5] Method according to one of claims 1 to 4, characterized bythat after an interruption in charging the traction battery due to a stationary fan (21), the traction battery will not be automatically restarted and charged. [6] Method according to one of claims 1 to 5, characterized by that the charger (8) provides a supply voltage for the fan electric motor (16) via the signal line (26). [7] Method according to claim 6, characterized by that the charger (8) provides a ground connection for the fan electric motor (16) via the signal line (27).

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