EP4786403A1

EP4786403A1 - Lift truck

Info

Publication number: EP4786403A1
Application number: EP26155155.0A
Authority: EP
Inventors: Andrea FOLIGNO; Paolo Ferrari
Original assignee: Toyota Material Handling Manufacturing Italy SpA
Current assignee: Toyota Material Handling Manufacturing Italy SpA
Priority date: 2025-01-30
Filing date: 2026-01-29
Publication date: 2026-08-05

Abstract

Described is a lift truck comprising an energy storage unit (4), consisting of a plurality of battery modules or packs (23), for powering a drive unit (2) and one or more auxiliary user devices (3);
an electric circuit (5) is designed for distributing energy from the energy storage unit (4) to the drive unit (2) and to the auxiliary user devices (3);
a single control and management system (6) of the lift truck (1) and of the passage of current from the energy storage unit (4) to the drive unit (2) and to the user devices (3) through the electric circuit (5);
the control and management system (6) comprises at least one module (7) for managing the energy storage unit (4), a solid state switch (9) and a single contactor (12), having a relative control card (11), for controlling the opening or closing of the passage of current towards the drive unit (2) and the auxiliary user devices (3);
the management module (7) of the energy storage unit (4) is configured to send a control signal (8) to the solid state switch (9) in response to which it switches a branch (10) of the electric circuit (5), for opening or closing, for powering the control card (11) of the contactor (12).

Description

This invention relates to a lift truck.
The current lift trucks, 100, which have a lithium-ion battery interchangeable with the lead-acid battery, are provided with two separate electronic management systems (as shown in Figure 1):

a battery management system (BMS) and
a tuck control system (TCS).

The BMS, 200, is responsible for managing the battery, mainly overseeing the energy flows (discharge and recharge) within the battery pack itself. The BMS integrates and communicates with the TCS, 300, through a digital communication line (CAN bus) that allows the exchange of data between the two systems.
However, the two systems do not share components and remain functionally independent.
Two independent management systems for the truck and the battery (BMS and TCS) result in redundancy of electrical components. In practice, duplicate components are required for each electronic system, both for the battery management system and for the truck control system.
The use of two separate control systems also results in a multi-stage starting sequence, before the battery electrical system (BMS) is started, which then, only after receiving an external input (such as, for example, a key turn), provides power and starts the truck electrical system (TCS).
In other words, the sequence of switching ON the lift truck comprises in succession:

the pushing of a power button 201 (by the truck driver);
activation of the BMS 202;
activation of the battery contactor (that is, electro-mechanical switch) 203;
the turning of key 301 (by the truck driver);
activation of the main truck contactor 302;
activation of the auxiliary truck contactor 303.

In addition, in order to facilitate the wired paths that connect the two systems, they result in a certain rigidity in the arrangement of the electrical components.
As a result, the start-up time and sequence for prior art solutions have significantly increased as a result of the redundancies presented and the additional manual activation step required.
In addition to this, the currently known solutions limit the space dedicated to the operator's seat, which is usually positioned above the battery housing, due to the overall size of the battery pack and the relative electrical system.
Moreover, according to the current solutions, the socket for the battery charging plug is positioned on one of the relative sides due to its proximity to the battery pack and the relative management system.
The lateral charging plug increases the overall lateral size of the truck during the charging operation, creating space limitations if a fleet of trucks is to be recharged at the same time.
In order to solve the critical issues found in the prior art, the need has been felt to develop a lift truck as described in independent claim 1 in which the two independent systems are replaced by a single system for management of the battery and the truck.
Further features of the invention are described in the accompanying dependent claims.
The advantages of the invention are more apparent in the non-limiting description which follows of a non-exclusive embodiment of a lift truck as illustrated by way of example only and, therefore, without limiting the scope of the invention, in which:

Figure 1 illustrates an operating diagram of the battery and the truck separated from each other as known;
Figure 2 illustrates a schematic top view of a lift truck according to the present invention with some parts removed to better highlight others;
Figure 3 is a schematic, scaled-up perspective view of the components of the lift truck of Figure 1;
Figure 4 illustrates an operating diagram of a single system for management and control of the lift truck and of an energy storage unit.

With reference to the accompanying drawings, the numeral 1 denotes a lift truck according to the invention.
The lift truck 1 comprises a driver's cab 21 and a load movement upright 22, positioned in front of the driver's cab 21.
The lift truck comprises a drive unit 2 and one or more auxiliary user devices 3.
The drive unit 2 is used to move the pair of drive wheels of the lift truck 1. In the illustrated embodiment, the drive unit 2 provides a pair of electric motors each associated with a respective wheel.
An example of an auxiliary user device 3 of the lift truck 1 is the operation of a hydraulic circuit for moving sliding members of the uprights 22 of the lift truck 1.
The lift truck 1 comprises an energy storage unit 4 for powering the drive unit 2 and the auxiliary user devices 3.
By way of example, the energy storage unit 4 is in the form of a lithium battery or a battery with fuel cells.
The energy storage unit 4 has a power cable 19, the positive cable.
An electric circuit 5 is designed for distributing energy from the energy storage unit 4 to the drive unit 2 and to the auxiliary user devices 3.
A single control and management system 6 configured to manage the passage of current from the energy storage unit 4 to the drive unit 2 and to the auxiliary user devices 3 through the electric circuit 5 and to manage the control of the lift truck 1.
The control and management system 6 comprises a management module 7 of the energy storage unit 4 configured to send a control signal 8 to a solid-state switch 9.
The solid state switch 9 is a so-called "solid state relay".
In response to receiving the control signal 8, the solid state switch 9 is configured to switch a branch 10 of the electrical circuit 5, for opening or closing, of power supply to a control card 11 of a contactor 12 to command the opening or closing of the passage of current to the drive unit 2 and the auxiliary user devices 3.
The contactor 12 is in the form of a electro-mecanical switch, for example of a Solid-State Relay (SSR).
Advantageously, the proposed solution comprises the integration of the two prior art independent systems into a single overall control and management system 6 based on the solid state switch 9 which allows a single power contactor to be used, simplifying both the architecture of the wiring diagram of the lift truck 1 and the economic aspect, since one of the two main contactors of the prior art systems is eliminated.
In the same way, the invention advantageously passes from a prior art solution that provides 3 power contactors to one that provides one power contactor and one signal contactor, with the latter less subject to failures given the lower level of energy and heat that it must manage. Advantageously, the redundancy of electrical components is reduced while maintaining the same level of safety.
The lift truck 1 comprises a button 13 for switching ON/OFF which can be operated by an operator.
The operation of the pushbutton 13 determines the generation of a corresponding signal 14 for switching ON/OFF the management module 7 of the energy storage unit 4.
Advantageously, the management of the energy flow by a single control and management system 6 significantly reduces the complexity of the lift truck start-up sequence, as it reduces the number of steps to be performed which makes the overall system less sensitive to failures. Advantageously, the switching ON time of the lift truck 1 is reduced with a saving in switching ON time of 10-15% compared to the prior art solution.
The present invention also relates to a method of switching ON the lift truck 1 in which the following steps are followed:

operating the switching ON/OFF button 13 (by a driver of the lift truck 1);
activating the management module 7;
activating the solid-state switch 9.

Advantageously, with respect to the prior art, the steps of the switching ON method are two instead of three.
Optionally, the lift truck 1 comprises a switching ON block 15 configured to send a response signal 16 to a respective control unit 17.
The response signal 16 is determined by the insertion of the key into the switching ON block 15 and by its relative position therein.
The control unit 17, when it receives the response signal 16, is configured to send a control signal 26 to the control card 11 of the contactor 12 for controlling the opening or closing of the passage of current towards the drive unit 2 and the auxiliary user devices 3.
Advantageously, the switching ON block 15 is not an indispensable component for starting/stopping the lift truck 1, unlike the prior art.
The switching ON method also provides as an option the activation step of the switching ON block 15 following the activation step of the solid state switch 9.
The control and management system 6 comprises a single power fuse 18 connected to the power cable 19, the positive cable, of the energy storage unit 4 and to the above-mentioned contactor 12.
The contactor 12 is connected to the power cable 19 downstream of the fuse 18, with reference to the direction of the flow of current.
The management module 7 of the energy storage unit 4 and the solid state switch 9 are also electrically connected to the power cable 19 of the energy storage unit 4.
The control and management system 6 comprises a single current sensor 20 connected to the management module 7.
Advantageously, the present invention provides for a lower number of electrical/electronic power components compared to the prior art, resulting in an obvious simplification and cost savings.
In addition, some copper connections and power cables can be removed, compared to the prior art BMS.
The energy storage unit 4 consists of a plurality of modules or battery packs 23.
The battery modules or packs 23 of the energy storage unit 4 are positioned in a housing compartment 24 and the management module 7 of the energy storage unit 4 is positioned outside the housing compartment 24 in a dedicated area.
Advantageously, the possibility of having the components of the power circuitry with greater flexibility outside the housing compartment 24 of the battery modules or packs 23, allows additional space to be gained for the operator in the driver's cab 21 and allows the components of the management module 7 of the energy storage unit 4 to be positioned in the most advantageous areas and not strictly close to the battery modules or packs 23.
A power socket 25 for recharging the battery modules or packs 23 is positioned in a rear zone of the lift truck 1 relative to a driver's cab 21.
This makes it possible to facilitate recharging operations in terms of lateral dimensions, allowing, for example, a fleet of lift trucks 1 to be charged next to each other, and to facilitate the operator in managing the switching ON/OFF of the external power supply in the power socket 25.

Claims

A lift truck comprising an energy storage unit (4), consisting of a plurality of battery modules or packs (23), for powering a drive unit (2) and one or more auxiliary user devices (3);
an electric circuit (5) is designed for distributing energy from the energy storage unit (4) to the drive unit (2) and to the auxiliary user devices (3); characterised in that it comprises

a single control and management system (6) configured to manage the passage of current from the energy storage unit (4) to the drive unit (2) and to the user devices (3) through the electric circuit (5) and to control the lift truck (1);

the control and management system (6) comprises at least one module (7) for managing the energy storage unit (4), a solid state switch (9) and a single contactor (12), having a relative control card (11), for controlling the opening or closing of the passage of current towards the drive unit (2) and the auxiliary user devices (3);

the management module (7) of the energy storage unit (4) is configured to send a control signal (8) to the solid state switch (9) in response to which it switches a branch (10) of the electric circuit (5), for opening or closing, for powering the control card (11) of the contactor (12).
The lift truck according to the preceding claim, characterised in that it comprises an ON/OFF pushbutton (13) which can be operated by an operator, the operation of the pushbutton (13) determines the generation of a corresponding signal (14) for switching ON/OFF the management module (7) of the energy storage unit (4).
The lift truck according to any one of the preceding claims, characterised in that it comprises a switching ON block (15) configured to send a response signal (16) to a respective control unit (17), in response to which it is configured to send a control signal (26) to the control card (11) of the contactor (12) for controlling the opening or closing of the passage of current towards the drive unit (2) and the auxiliary user devices (3).
The lift truck according to any one of the preceding claims, characterised in that the control and management system (6) comprises a single fuse (18) connected to a power cable (19) of the energy storage unit (4) and to the above-mentioned contactor (12).
The lift truck according to any one of the preceding claims, characterised in that the control and management system (6) comprises a single current sensor (20) connected to the management module (7).
The lift truck according to any one of the preceding claims, characterised in that the battery modules or packs (23) of the energy storage unit (4) are positioned in a housing compartment (24) and the management module (7) of the energy storage unit (4) is positioned outside the housing compartment (24) in a dedicated area.
The lift truck according to any one of the preceding claims, characterised in that it comprises a power socket (25) for recharging the battery modules or packs (23) positioned in a rear zone of the lift truck (1) relative to a driver's cab (21).
The lift truck according to any one of the preceding claims, characterised in that the management module (7) of the energy storage unit (4), the solid state switch (9) and the contactor (12) are electrically connected to a power cable (19) of the energy storage unit (4).
A method for switching ON a lift truck according to any one of claims 1 to 8, characterised in that it comprises the following steps one after another:
- pressing the ON/OFF pushbutton (13);

- activating the management module (7);

- activating the solid state switch (9) after which the lift truck (1) is switched ON.
The method according to claim 9, characterised in that it comprises a step of activating the switching ON block (15) after the step of activating the solid state switch (9).