EP4628659A1

EP4628659A1 - Improved work vehicle and control method thereof

Info

Publication number: EP4628659A1
Application number: EP25168672.1A
Authority: EP
Inventors: Stefano Fiorati; Harald DANNERBAUER; Davide CRISTOFORI
Original assignee: CNH Industrial Italia SpA
Current assignee: CNH Industrial Italia SpA
Priority date: 2024-04-05
Filing date: 2025-04-04
Publication date: 2025-10-08

Abstract

A work vehicle (1) comprising an internal combustion engine (9), a hydraulic actuator (11); and a hydraulic arrangement (10) configured to provide a pressurized hydraulic fluid to the hydraulic actuator (11); the hydraulic arrangement (10) comprising: an electro-hydraulic portion (20); a hydraulic circuit (16) adapted to fluidly connect the outlet of the electro-hydraulic portion (20) with the hydraulic actuator (11). The electro-hydraulic portion (20) comprising: an electric machine (22) carried by the internal combustion engine (9); accumulator means (26) electrically connected to the electric machine (22) and configured to store the electric energy provided by said first electric machine (22); and electro-hydraulic pumping means (24), which are electrically connected to the electric machine (22) and to the accumulator means (26) and are fluidly connected to the hydraulic circuit (16).

Description

TECHNICAL FIELD

The present invention relates to a work vehicle, in particular to an agricultural vehicle such as a tractor, and to the related control method.
The present invention finds its preferred, although not exclusive, application in a hydraulic system of a work vehicle. Reference will be made to this application by way of example below, without however losing in generality.

BACKGROUND OF THE INVENTION

As is known, to save fuel, passenger and commercial vehicles are provided with a start and stop system configured to temporarily shut down the internal combustion engine when the vehicle is stationary, for example at a traffic light or queueing in traffic.
However, until now work vehicles such as tractors or similar agricultural vehicles have not been equipped with such start and stop system, as their internal combustion engine drives a great number of auxiliary components of the same vehicles, such as the hydraulic system powering the power steering system, the braking system, the clutches and selectors of the drivetrain assembly or similar hydraulically actuated utilities.
Therefore, even temporary shutdown of the internal combustion engine would result in a drop of the pressure of the hydraulic system, with the obvious drawbacks that this entails. Indeed, without the internal combustion engine driving the hydraulic system, it is not possible to operate the power steering system, the braking system, the clutches and selectors of the drivetrain assembly or the other similar hydraulically actuated utilities.
In addition, once restarted the internal combustion engine, a significant amount of time is needed for the pressure within the hydraulic system to build up again.
In view of the above, the need is felt to provide an improved work vehicle and a control method thereof able to overcome the aforementioned drawbacks.
Aim of the present invention is to satisfy the above-mentioned need in an optimized and cost-effective manner.

SUMMARY OF THE INVENTION

The aforementioned aims are reached by a work vehicle and by the methods as claimed in the appended set of claims.

BRIEF DESCRIPTION OF DRAWINGS

For a better understanding of the present invention, a preferred embodiment is described in the following, by way of a non-limiting example, with reference to the attached drawings, wherein:

Figure 1 is a schematic representation of a work vehicle realized according to the present invention, with parts removed for clarity; and
Figures 2 and 3 are schematic representation of the operation of the work vehicle illustrated in Figure 1.

DETAILED DESCRIPTION OF THE INVENTION

With reference to Figure 1, reference number 1 denotes as a whole a work vehicle, in particular an agricultural vehicle, such as a tractor, a combine harvester, a telehandler or the like.
As known, work vehicle 1 comprises a body (not illustrated) movable on the ground thanks to at least a pair of ground engaging means, such as wheels or tracks.
In addition, work vehicle 1 further comprises a powertrain assembly 7, which is carried by the work vehicle body and is configured to provide torque to ground engaging means to allow motion of the work vehicle body with respect to the ground.
With reference to the exemplary embodiment shown in Figure 1, powertrain assembly 7 comprises an internal combustion engine 9, for example a diesel-powered or a methane-powered internal combustion engine.
In addition, work vehicle 1 further comprises a drivetrain assembly (not illustrated), which is operatively interposed between internal combustion engine 9 and the ground engaging means and is configured to transmit the torque provided by the same internal combustion engine 9 to ground engaging means, in a manner per se known and therefore not further described.
Drivetrain assembly may comprise a continuously variable transmission such as a power-split hydromechanical transmission, a full power-shift transmission, a semi power-shift transmission or a combination thereof.
In addition or alternative, drivetrain assembly may be provided with an electric-hybrid architecture, for example a serial-hybrid architecture, a parallel hybrid architecture or a combination thereof, as per se known and therefore not further described.
As per se known, work vehicle 1 comprises one or more hydraulically actuated system (not illustrated), such as a braking system, a power steering system, hydraulically actuated clutches and/or selectors of the drive train assembly, a front hitch, a rear hitch and/or the like.
For example, said hydraulically actuated system preferably comprises at least a front and/or a rear hitch assembly, in particular a front and/or a rear three-point hitch assembly, which are configured to be connected to an implement adapted to be towed or carried by work vehicle 1, as per se known.
Preferably, said hitch assembly comprises a plurality of links rotatably carried by the body of work vehicle and configured to be mechanically connected to the implement.
Such hydraulically actuated systems comprise at least one hydraulic actuator 11, such as a hydraulic motor and/or a hydraulic cylinder.
According to a non-limiting and exemplary embodiment of the present invention, the hydraulic actuator 11 may comprise at least one hydraulic cylinder operatively interposed between the body of work vehicle and at least one of said links and configured to rotate the same link with respect to the body of work vehicle.
In addition, with reference to the preferred embodiment of the present invention, work vehicle 1 further comprises a hydraulic arrangement 10, which is configured to be fluidly connected to one or more hydraulic utilities/actuators 11 of work vehicle 1 and is configured to provide pressurized hydraulic fluid to these latter.
As per se known, hydraulic arrangement 10 may comprise a low-pressure hydraulic arrangement configured to actuate the hydraulic actuators of hydraulic-steering system, braking system and/or drivetrain assembly. In particular, the pressure of the hydraulic fluid within said low-pressure hydraulic arrangement may be comprises for example between 20 bars and 30 bars.
In addition, hydraulic arrangement 10 may comprise a high-pressure hydraulic arrangement configured to actuate the front and rear hitch and/or configured to provide pressurized hydraulic fluid towards an implement adapted to be carried by the same work vehicle 1. In particular, the pressure of the hydraulic fluid within said high-pressure hydraulic arrangement may be comprises for example between 200 bars and 300 bars.
With reference to the exemplary embodiment illustrated in Figure 1, hydraulic arrangement 10 preferably comprises at least one hydraulic pump 14 carried by internal combustion engine 9.
More in detail, hydraulic pump 14 is preferably mechanically connected to internal combustion engine 9 via transmission components 15, such as gearings, clutches, shafts, flexible transmission components or a combination thereof, in order to be driven in rotation.
In use, hydraulic pump 14 is configured to displace hydraulic fluid from a tank (not illustrated) and to provide at outlet a pressurized flow of the same hydraulic fluid.
In addition, hydraulic arrangement 10 comprises a hydraulic circuit 16 adapted to fluidly connect the outlet of hydraulic pump 14 with actuator/s 11 and to control/regulate the pressure/flowrate of the hydraulic fluid fed towards the same actuator/s 11, as per se known. In particular, hydraulic circuit 16 may comprise a plurality of hydraulic lines and a plurality of hydraulic valves adapted to regulate/control the flow of the pressurized hydraulic fluid from the hydraulic pump 14 to the corresponding actuator 11.
With reference to the preferred embodiment of the present invention, hydraulic arrangement 10 further comprises an electro-hydraulic portion 20, which is arranged in parallel to hydraulic pump 15 and is adapted to be fluidly connected to hydraulic circuit 16, to provide this latter with a pressurized flow of hydraulic fluid.
More in detail, electro-hydraulic portion 20 comprises: an electric machine 22, in particular an electric generator, carried by internal combustion engine 9; and an electro-hydraulic pumping means 24, which is electrically connected to first electric machine 22 and in turn is hydraulically connected to hydraulic circuit 16.
In addition, according to the preferred embodiment illustrated in Figure 1, work vehicle 1 may further comprise an electric energy storage system 26, in the following also referred to as "accumulator means", which is electrically connected to electric machine 22 and to electro-hydraulic pumping means 24 by means of electric power management means 28, and is configured to store at least part of the electric energy produced by electric generator 22 and to provide electric energy to electro-hydraulic pumping means 24.
More in detail, electric machine 22 is preferably mechanically coupled to the internal combustion engine 9 and, as known, is configured to transform the mechanical energy provided by the same internal combustion engine 9 into electric energy. Such electric energy may be stored into the accumulator means 26 and/or may be provided to electro-hydraulic pumping means 24.
According to the preferred embodiment of the present invention, accumulator means 26 comprises chemical-type accumulators. More in detail, accumulator means 14 preferably comprises a battery pack, in particular a lithium-ion battery pack.
Alternatively, accumulator means 26 may comprise one or more supercapacitors.
Electric power management means 28 preferably comprise a power distribution unit, PDU, electrically connected to electric machine 22, to electro-hydraulic pumping means 24 and accumulator means 26, in order to manage the electric energy transfer among them.
Preferably, the connection of power distribution unit 28 is realized via inverters, which are operatively interposed between the accumulator means 26 and respectively electric machine 22 or electro-hydraulic pumping means 24.
With reference to the preferred embodiment of the present invention, electro-hydraulic pumping means 24 preferably comprises a second electric machine 30, in particular an electric motor, electrically connected to electric machine 22 and to power distribution unit 28.
In addition, electro-hydraulic pumping means 24 preferably comprises a hydraulic pump 32, which is mechanically connected to second electric machine 30, in order to be driven in rotation.
In use, hydraulic pump 32 is adapted to suck hydraulic fluid from a tank and to provide at outlet a pressurized flow of the same hydraulic fluid.
In particular, hydraulic pump 32 is preferably a high-pressure hydraulic pump configured to provide at outlet pressurized hydraulic fluid at a pressure advantageously higher than 200 bars.
Preferably, the outlet of hydraulic pump 32 is fluidly connected to hydraulic circuit 16 via a hydraulic line or conduit or manifold 34.
Hydraulic line 34 may be provided with hydraulic valves configured to control the flow of the pressurized hydraulic fluid provided at outlet by hydraulic pump 32 within the same line 34.
For instance, hydraulic line 34 may be provided with one or more pressure relief valve and/or ore or more non-return valve and/or one or more flow control valve configured to selectively control the flow of the pressurized hydraulic fluid provided at outlet by hydraulic pump 32 within the same line 34.
With reference to the exemplary embodiment illustrated in Figure 1, work vehicle 1 further comprises an electronic control unit 40, which is operatively connected at least to hydraulic arrangement 10 and to powertrain assembly 7, and comprises elaboration means configured to control the operation of powertrain assembly 7and/or hydraulic arrangement 10 according to the control method described more in detail in the following.
Such control method, for instance, may be deployed into a specific computer program, which can be downloaded into the electronic control unit 40 and is configured to be executed by the same electronic control unit 40.
More in detail, electronic control unit 40 may comprise processing means and storage means. Storage means may include computer-readable means having stored thereon which include instructions which, when executed by the processing means, causes the same processing means to carry out the control method as described in the following.
In addition, work vehicle 1 may comprise user input means 42, such as pedals, a joystick, a lever, a knob or a combination thereof, which are operatively connected to electronic control unit 40 and are configured to be handled/operated by a user in order to impart commands adapted to control the operation of powertrain assembly 7 and/or hydraulic arrangement 10.
With reference to the preferred embodiment of the present invention, electronic control unit 40 may be configured to determine the operation status of internal combustion engine 9.
When internal combustion engine 9 is off, electronic control unit 40 may be configured to determine the state of charge (SoC) of accumulator means 26.
Then, depending on the command imparted by the operator, if the state of charge of accumulator means 26 is high enough, electronic control unit 40 may be configured to operate electro-hydraulic pumping means 24 to provide pressurized hydraulic fluid toward hydraulic circuit 16 by absorbing electric energy from accumulator means and maintaining the internal combustion engine 9 off.
On the other hand, depending on the command imparted by the operator, if the state of charge of accumulator means 26 is not high enough, electronic control unit 40 may be configured to switch on internal combustion engine 9, in order to operate hydraulic pump 14 and or to provide electric energy to electro-hydraulic pumping means 24 via electric machine 22, in order to provide pressurized hydraulic fluid toward hydraulic circuit 16.
In view of the above, the operation of work vehicle and implement combination 1 according to the present invention is the following.
When the internal combustion engine 9 is off, electro-hydraulic portion 20 may be operated to provide pressurized hydraulic fluid towards hydraulic circuit 16.
More in detail, when internal combustion engine 9 is off, electro-hydraulic pumping means 24 may absorb electric energy from accumulator means 26, in order to be actuated and provide pressurized hydraulic fluid towards hydraulic circuit 16 of work vehicle 1.
Such operation is schematically represented in Figure 3, wherein the arrows indicated the flows of mechanical, electrical or hydraulic energy between the various components of work vehicle and implement combination 1.
Vice-versa, when internal combustion engine 9 is running, it drives in rotation electric machine 22, in order to generate electric energy and recharge accumulator means 26.
In addition, when internal combustion engine 9 is running, it may drive in rotation also hydraulic pump 14, in order to provide pressurized hydraulic fluid towards hydraulic circuit 16, in order to be able to operate hydraulic actuators 11 of work vehicle 1.
In such operation condition, also electro-hydraulic pumping means 24 may be operated to provide pressurized hydraulic fluid towards hydraulic circuit 16, in order to be able to operate hydraulic actuators 11 accordingly.
Such operation is schematically represented in Figure 2, wherein the arrows indicated the flows of mechanical, electrical or hydraulic energy between the various components of work vehicle and implement combination 1.
According to the disclosed embodiment, the present invention is directed to a method for controlling a work vehicle 1 as described above.
The method comprises the following steps:

a) receiving a request to provide pressurized hydraulic fluid to hydraulic circuit 16,
b) determining if internal combustion engine 9 is on or off,
c) if the internal combustion engine 9 is off, determining the state of charge of accumulator means 26,
d) if the state of charge of accumulator means 26 is high enough to meet the request received at step a), keeping internal combustion engine 9 shut off and operate electro-hydraulic pumping means 24 according to the request received at step a)
e) if the state of charge of accumulator means 26 is not high enough to meet the request received at step a), turning internal combustion engine 9 on and operate hydraulic pump 14 and/or electro-hydraulic pumping means 24 according to the request received at step a).

More in detail, step c) preferably comprises to determine if the state of charge of accumulator means 26 overcomes a predetermined threshold.
For example, stap c) may comprise to determine if the state of charge of accumulator means 26 is equal or greater than 50%.
In view of the foregoing, the advantages of the work vehicle and implement combination and of the related operation method according to the present invention are apparent.
In fact, thanks to the proposed arrangement, it is possible to operate the hydraulic actuators 11 of work vehicle 1 while maintaining the internal combustion engine 9 off, with the obvious advantages that this entails.
In particular, this allows to provide the work vehicle 1 with a start and stop system without however losing power at the hydraulically actuated system when the internal combustion engine is off.
This in particular allows to save fuel and to reduce the noise and pollution emission of work vehicle 1, as it allows to greatly reduce the time interval when the internal combustion engine of work vehicle 1 is idling.
The proposed arrangement, moreover, is particularly suitable for hybrid-electric work vehicles, wherein the internal combustion engine may be kept shut off for long periods of time and the supply of pressurized hydraulic fluid towards hydraulic circuit 16 is still guaranteed by electro-hydraulic pumping means 24.
It is clear that modifications can be made to the described work vehicle and method which do not extend beyond the scope of protection defined by the claims.
For instance, accumulator means 26 may be a part of the hybrid portion of a drivetrain assembly or other apparatuses of work vehicle 1.
Similarly, power distribution unit 28 may be a part of other work vehicle apparatuses, such as a power distribution unit of a hybrid electric drivetrain assembly and/or the like.
Lastly, according to a simplified embodiment, implement 5 may not be provided with electronic control unit 45.

Claims

A work vehicle (1) comprising:
• a body movable on the ground by means of a plurality of ground-engaging means; and

• a powertrain assembly (7), which is carried by said body and includes an internal combustion engine (9) configured to provide torque to said ground-engaging means to allow motion of the work vehicle on the ground;

• at least one hydraulic actuator (11); and

• a hydraulic arrangement (10), which is fluidly connected to said hydraulic actuator (11) and is configured to provide a pressurized hydraulic fluid to said hydraulic actuator (11);

said hydraulic arrangement (10) comprising:
• an electro-hydraulic portion (20), which is mechanically connected to said internal combustion engine (9) and is adapted to suck said hydraulic fluid from a tank and to provide at outlet a pressurized flow of said hydraulic fluid; and

• a hydraulic circuit (16), which is adapted to fluidly connect the outlet of said electro-hydraulic portion (20) with said hydraulic actuator (11);

said electro-hydraulic portion (20) comprising:
• a first electric machine (22) carried by said internal combustion engine (9) and configured to transform the mechanical energy provided by said internal combustion engine (9) into electric energy;

• accumulator means (26) electrically connected to said first electric machine (22) and configured to store the electric energy provided by said first electric machine (22); and

• electro-hydraulic pumping means (24), which are electrically connected to said first electric machine (22) and to said accumulator means (26), are fluidly connected to said hydraulic circuit (16) and are adapted to suck hydraulic fluid from a tank and to provide a pressurized flow of said hydraulic fluid to said hydraulic circuit (16).
Work vehicle according to claim 1, wherein said hydraulic arrangement (10) further comprises a first hydraulic pump (14), which is carried by said internal combustion engine (9), is adapted to suck said hydraulic fluid from a tank and to provide at outlet a pressurized flow of said hydraulic fluid, and is arranged in parallel to said electro-hydraulic portion (20).
Work vehicle according to claim 1 or 2, wherein said electro-hydraulic pumping means (24) comprise:
• a second electric machine (30) electrically connected to said first electric machine (22) and to said accumulator means (26); and

• a second hydraulic pump (32), which is carried by said second electric machine (30).
Work vehicle according to claim 1, 2 or 3, wherein said electro-hydraulic portion (20) further comprises a power distribution unit (28), which is electrically connected to said first electric machine (22), to said electro-hydraulic pumping means (24) and to said accumulator means (26) and is configured to manage the electric energy transfer among these latter.
Work vehicle according to any of the preceding claims, wherein said electro-hydraulic portion (20) further comprises a hydraulic line (34) fluidly connecting the outlet of said electro-hydraulic pumping means (24) with said hydraulic circuit (16).
Work vehicle according to claim 5, wherein said electro-hydraulic portion (20) further comprises a pressure relief valve and/or a flow control valve and/or a non-return valve arranged along said hydraulic line (34).
Work vehicle according to any of the preceding claims, further comprising a hydraulically actuated system selected from the group comprising: a braking system, a power steering system, hydraulically actuated clutches and/or selectors of a drivetrain assembly, a front hitch, a rear hitch;
said hydraulically actuated system comprising said least one hydraulic actuator (11).
Work vehicle according to any of the preceding claims, further comprising an electronic control unit (40), which is operatively connected at least to said hydraulic arrangement (10) and to said powertrain assembly (7), and comprises elaboration means configured to control the operation of said powertrain assembly (7) and/or of said hydraulic arrangement (10);
said electronic control unit (40) being configured to:
a) receive a request to provide pressurized hydraulic fluid to said hydraulic circuit (16),

b) determine if said internal combustion engine (9) is on or off,

c) if said internal combustion engine (9) is off, determine the state of charge of said accumulator means (26),

d) if the state of charge of said accumulator means (26) is high enough to meet the request received at said step a), keep said internal combustion engine (9) shut off and operate said electro-hydraulic pumping means (24) according to the request received at said step a), and

e) if the state of charge of said accumulator means (26) is not high enough to meet the request received at said step a), turn said internal combustion engine (9) on and operate said first hydraulic pump (14) and/or said electro-hydraulic pumping means (24) according to the request received at step a).
A method for controlling a work vehicle realized according to any of the preceding claims;
said method comprising the following steps:
f) receiving a request to provide pressurized hydraulic fluid to said hydraulic circuit (16),

g) determining if said internal combustion engine (9) is on or off,

h) if said internal combustion engine (9) is off, determining the state of charge of said accumulator means (26),

i) if the state of charge of said accumulator means (26) is high enough to meet the request received at said step a), keeping said internal combustion engine (9) shut off and operating said electro-hydraulic pumping means (24) according to the request received at said step a), and

j) if the state of charge of said accumulator means (26) is not high enough to meet the request received at said step a), turning said internal combustion engine (9) on and operating said first hydraulic pump (14) and/or said electro-hydraulic pumping means (24) according to the request received at step a).
Method according to claim 9, wherein said step c) comprises the step of determining/verifying if the state of charge of said accumulator means (26) is higher or equal than a predetermined threshold.