EP4592239A1

EP4592239A1 - Work vehicle including a fork supporting arm

Info

Publication number: EP4592239A1
Application number: EP25153923.5A
Authority: EP
Inventors: Adriano GARRAMONE; Andrea Gravili; Antonio Venezia; Stefano Liberti
Original assignee: CNH Industrial Italia SpA
Current assignee: CNH Industrial Italia SpA
Priority date: 2024-01-25
Filing date: 2025-01-24
Publication date: 2025-07-30
Also published as: IT202400001440A1

Abstract

Work vehicle (VEH) comprising an arm (A) comprising a first segment (A_1) connected to a chassis (F) of the vehicle and a fork (FK) hinged to the first segment, a propulsion system such as to allow movement of the vehicle with respect to a support surface, a processing unit (VCU) configured to perform a function called "Safety Brake" including a step of automatically rotating said fork backwards during braking of the vehicle.

Description

Field of the invention

The present invention relates to the field of work vehicles comprising an arm supporting a fork connected to the arm for handling pallets.

State of the art

Work vehicles are essentially divided into construction vehicles and agricultural vehicles.
Those work vehicles equipped with an arm are generally capable of supporting a fork for moving loads and pallets. Often, especially in the agricultural field it may be necessary to move a pile of stacked pallets and transport the pile along a route.
When the vehicle brakes, there is the risk that the stack of pallets could tip forward.
Therefore, operators are often called upon to make use of their experience to adjust the brake pedal to avoid accidents.
Unless specifically excluded in the detailed description that follows, what is described in this chapter is to be considered as an integral part of the detailed description.

Summary of the invention

The aim of the present invention is to indicate a work vehicle comprising an articulated arm supporting a fork which makes the handling of stacks of pallets easier.
The basic idea of the present invention is to implement an automatic correction of the fork position in order to tilt it backwards during a braking operation.
The dependent claims describe preferred variants of the invention, forming an integral part of the present description.

Brief description of the figures

Further objects and advantages of the present invention will be clear from the following detailed description of an example of its implementation (and its variants) and from the attached drawings given purely for explanatory and non-limiting purposes, in which:

Fig. 1 discloses a work vehicle modified according to the present invention;
Fig. 2 shows an electro-hydraulic circuit implemented in the vehicle of Fig. 1.

The same reference numbers and letters in the figures identify the same elements or components or functions.
It should also be noted that the terms "first", "second", "third", "higher", "lower" and the like may be used here to distinguish various elements. These terms do not imply a spatial, sequential, or hierarchical order for the modified elements unless specifically indicated or inferred from the text.
The elements and characteristics illustrated in the different preferred embodiments, including the drawings, can be combined with each other without departing from the scope of protection of the present application as described below.

Detailed description

Fig. 1 illustrates a work vehicle VEH equipped with an arm A including a first element A_1, substantially elongated, hinged to the chassis F of the vehicle and a second element FK, consisting of a fork, hinged to the first element. More specifically, a first end of the first element is connected to the chassis F of the vehicle, while a second end, opposite to the first, supports the second element in a rotary manner.
Fig. 2 shows an electro-hydraulic circuit HC comprising

a hydraulic pump P arranged to supply the circuit;
a pair of open center directional valves V1, V2 to control the same number of actuators A1 and A2.

The VCU processing unit is configured to receive as input an electrical signal generated by the joystick JK, located in the vehicle cab CAB and consequently to control the condition of the valves V1 and V2.
The first hydraulic actuator A1 is associated with the first element A_1 of the arm A and the second hydraulic actuator A2 is associated with the second element FK of the arm A to control the configurations that each element can assume with respect to the relative constraint, i.e. respectively the frame F of the vehicle and the first element A_1.
The actuators A1 and A2 are double acting. Each of them has a stem to which a position sensor S1 and S2 is associated. The processing unit, based on the signals generated by the position sensors S1, S2, is able to calculate the current kinematic configuration of arm A.
The processing unit VCU is also configured to receive as input a signal representative of the vehicle speed VS from a sensor VS named in the same way, which can be for example, a sensor associated with a vehicle wheel, or a satellite receiver, etc...
The processing unit VCU is also configured to receive as input another signal representing the position BK of the brake pedal or lever via a dedicated sensor BK, named in the same way, which can for example be a sensor associated with the same lever or pedal. In the following description, we will refer to the pedal, even if the latter can be replaced by a lever.
Furthermore, the processing unit can check whether the "Safety Brake" function is enabled. This function can be enabled in any way, for example, through a dedicated switch ASW, or through a setting menu of a vehicle dashboard display (not shown) for example with a touch screen.
When it recognized that the following conditions are met:

C1: the current speed of the vehicle exceeds a first predetermined threshold, for example 5 km/h,
C2: the brake pedal is currently depressed beyond a second predetermined threshold, for example 3°,
C3: the "Safety Brake" function is currently set as enabled, then

On the other hand, if at least one of the aforementioned conditions C1 - C3 is not verified, then the Safety Brake function is not active, even if it is enabled.
It is important to distinguish between enabling and activating the aforementioned function. Its enabling represents a necessary but not sufficient condition for the same function to be active, i.e. to actually be executed.
The aforementioned function is deactivated when at least one of the following conditions is verified:

the current speed of the vehicle is below the first predetermined threshold,
vehicle braking is stopped, i.e. when the brake pedal is released below the second predetermined threshold,
the "Safety Brake" function is disabled.

The backward rotation is generally called "roll back". The roll back limit position can be set via a human/machine interface device or can coincide with the limit switch of the fork reverse rotation.
According to a preferred aspect of the invention, the roll back operation is stopped when the aforementioned function is deactivated, therefore the roll back operation is also interrupted when the braking of the vehicle is stopped. Evidently, the braking time must be long enough to allow the fork to reach the limit position, otherwise, the roll back operation is interrupted.
According to a preferred aspect of the invention, the first speed threshold is a function of the weight of the transported load. More precisely, the first threshold is inversely proportional to the load transported, therefore the greater the load, the lower the value of the first threshold and vice versa.
A force sensor LDS is associated directly with the fork or is associated indirectly with the fork, for example, the boom, or a front suspension of the vehicle to measure or estimate the weight of the transported load.
According to a preferred aspect of the invention, when the Safety Brake function is performed, i.e., the fork is tilted back during braking of the vehicle, then a signal generated by the joystick JK arranged to control the arm is ignored or inhibited. In other words, control of the arm using the joystick is inhibited.
Advantageously, the operator is prevented from interfering with the Safety Brake function.
The present invention can advantageously be carried out by means of a computer program which includes coding means for carrying out one or more steps of the method, when this program is executed on a computer. Therefore, it is understood that the scope of protection extends to said computer program and further to computer readable means comprising a recorded message, said computer readable means comprising program coding means for carrying out one or more steps of the method, when said program is executed on a computer.
Constructive variations to the non-limiting example described are possible, without however departing from the scope of protection of the present invention, including all equivalent embodiments for a person skilled in the art, to the content of the claims.
From the above description, the person skilled in the art is able to realize the object of the invention without introducing further construction details.

Claims

Work vehicle (VEH) including
- an arm (A) comprising a first segment (A_1) connected to a chassis (F) of the vehicle and a fork (FK) hinged to the first segment,

- an electro-hydraulic circuit (HC) to move the arm,

- a joystick (JK) to control the arm (A),

- a propulsion system allowing the vehicle to move with respect to a support surface,

- a processing unit (VCU) configured to receive as input a first electrical signal generated by said joystick and to control said electro-hydraulic circuit in response to said first electrical signal received and configured to keep the arm stationary when the joystick is released,
wherein the processing unit is configured to perform a function, named as "Safety Brake", including a step of automatically rotating said fork backwards during braking of the vehicle.
Vehicle according to claim 1, wherein said processing unit is configured to perform said Safety Brake function when, during said braking, all of the following conditions are verified:
- (C1:) a vehicle speed (VS) exceeds a first predetermined threshold,

- (C2:) a brake pedal is currently depressed beyond a second predetermined threshold,

- (C3:) the "Safety Brake" function is currently set as enabled.
The vehicle according to claim 1 or 2, wherein the vehicle is equipped with a weight sensor (LDS) associated with said fork for measuring or estimating a load transported by said fork and wherein the processing unit is configured to receive input a second electrical signal generated by said weight sensor and to vary a value of said first predetermined threshold in an inversely proportional manner to a current weight value represented by said second electrical signal.
Vehicle according to any one of the preceding claims, wherein the processing unit is configured to inhibit the control of said arm by means of said joystick during an execution of said Safety Brake function.
Vehicle according to any of the previous claims, further comprising a human/machine interface device to enable said Safety Brake function and preferably to set said second threshold and an inverse proportionality factor between said current weight value and said first predetermined threshold.
Vehicle according to any one of the preceding claims, wherein said processing means is configured to interrupt said reverse rotation in response to the deactivation of said Safety Brake function, or when the current speed of the vehicle is below the first predetermined threshold, or when vehicle braking is stopped, i.e. when the brake pedal is released below the second predetermined threshold or when said "Safety Brake" function is disabled.
Method of controlling a fork of a work vehicle (VEH) comprising
- an arm (A) comprising a first segment (A_1) connected to a chassis (F) of the vehicle and said fork (FK) hinged to the first segment,

- an electro-hydraulic circuit (HC) to move the arm,

- a joystick (JK) to control the arm (A),

- a propulsion system allowing the vehicle to move with respect to a support surface,

- a processing unit (VCU) configured to receive a first electrical signal generated by said joystick and to control said electro-hydraulic circuit in response to said first electrical signal received and configured to keep the arm stationary when the joystick is released,
the method comprising a step of automatically rotating said fork backwards during braking of the vehicle.
The method of claim 7, further comprising a preliminary step of ascertaining that all of the following conditions are met:
- (C1:) a vehicle speed (VS) exceeds a first predetermined threshold,

- (C2:) a brake pedal is depressed beyond a second predetermined threshold,

- (C3:) the "Safety Brake" function is currently set as enabled.
The method according to claim 8, wherein said preliminary step comprises
- acquisition of the current speed of the vehicle,

- acquisition of the current position of the brake pedal,

- acquisition of an enabling status of the Safety brake function.
A computer program comprising instructions for causing the processing unit (VCU) of claim 1 to implement the control method according to claims 1 to 8.
A computer readable medium having stored the program of claim 10.