Control of torque in electric lift trucks

A control unit for controlling a torque generated by at least one electric motor of an electric lift truck, the control unit comprising:

• at least one processor;
• and
• at least one memory including computer program code;
• the at least one memory and the computer program code configured to, with the at least one processor, define a target speed of the electric lift truck and a maximum speed deviation speed, and further cause the control unit to:
• detect a fulfilment of at least one criterion when the torque of the at least one electric motor is in a first mode corresponding to a mode in which the at least one electric motor is caused to generate a nominal torque of the at least one electric motor, the at least one criterion comprising an input to the control unit of one of an actual speed value of the electric lift truck or an actual acceleration value of the electric lift truck, and wherein the target speed and maximum speed deviation are determined in conjunction with a detection of the fulfilment of the at least one criterion indicating insufficient amount of the torque in the first mode to maintain a motion of the electric lift truck being performed on a basis of a change in the motion of the electric lift truck,
• determining a current output to increase the actual speed of the electric lift truck to the target speed automatically without a user interaction through a user interface of the electric lift truck, and operating an electrical drive of the at least one electric motor to generate a control signal to the at least one electric motor to generate, in a temporal basis, a torque being larger than the torque of the at least one electric motor in the first mode to change the torque to an increased torque mode for maintaining the motion of the electric lift truck.

A non-transitory computer-readable medium on which is stored a computer program comprising computer readable program code for controlling a torque generated by at least one electric motor of an electric lift truck which, when the program code is executed by at least one processor, cause a control unit of the electric lift truck to perform the method comprising:

• detecting a fulfilment of at least one criterion when the torque of the at least one electric motor is in a first mode corresponding to a mode in which the at least one electric motor is caused to generate a nominal torque of the at least one electric motor, a detection of the fulfilment of the at least one criterion indicating insufficient amount of the torque in the first mode to maintain a motion of the electric lift truck being performed on a basis of a change in the motion of the electric lift truck, the at least one criterion comprising an input to the control unit of one of an actual speed value of the electric lift truck or an actual acceleration value of the electric lift truck,
• in conjunction with the detection of the fulfilment of the at least one criterion, defining a target speed and a maximum speed deviation,
• determining a current output to increase the actual speed of the electric lift truck to the target speed automatically without a user interaction through a user interface of the electric lift truck, and operating an electrical drive of the at least one electric motor to generate a control signal to the at least one electric motor to generate, in a temporal basis, a torque being larger than the torque of the at least one electric motor in the first mode to change the torque to an increased torque mode for maintaining the motion of the electric lift truck.

An electric lift truck comprising:

• an electric motor,
• an electrical drive, and
• a control unit comprising:
• at least one processor;
• and
• at least one memory including computer program code;
• the at least one memory and the computer program code configured to, with the at least one processor, cause the control unit to:
• detect a fulfilment of at least one criterion when the torque of the at least one electric motor is in a first mode corresponding to a mode in which the at least one electric motor is caused to generate a nominal torque of the at least one electric motor, a detection of the fulfilment of the at least one criterion indicating insufficient amount of the torque in the first mode to maintain a motion of the electric lift truck being performed on a basis of a change in the motion of the electric lift truck, the at least one criterion comprising an input to the control unit of one of an actual speed value of the electric lift truck or an actual acceleration value of the electric lift truck,
• define a target speed and a maximum speed deviation in conjunction with the detection of the fulfilment of the at least one criterion;
• and
• determining a current output to increase the actual speed of the electric lift truck to the target speed automatically without a user interaction through a user interface of the electric lift truck, and
• operate an electrical drive of the at least one electric motor to generate a control signal to the at least one electric motor to generate, in a temporal basis, a torque being larger than the torque of the at least one electric motor in the first mode to change the torque to an increased torque mode for maintaining the motion of the electric lift truck.