US-20260126062-A1 - HYDRAULIC SYSTEM FOR A VEHICLE AND A COMPUTER-IMPLEMENTED METHOD

US20260126062A1US 20260126062 A1US20260126062 A1US 20260126062A1US-20260126062-A1

Abstract

A hydraulic system for a vehicle is provided. The hydraulic system includes a first electric motor, a second electric motor, a gearbox arranged to be driven by the first and second electric motors, a hydraulic pump arranged to be driven by the gearbox, and a control arrangement configured to individually control the first and second electric motors to either run at a reference speed or to deliver a reference torque and during operation control at least one of the first and second electric motors to deliver a reference torque.

Inventors

Alessandro CARNEVALI

Assignees

VOLVO CONSTRUCTION EQUIPMENT AB

Dates

Publication Date: 20260507
Application Date: 20260102
Priority Date: 20230404

Claims (20)

1 . A hydraulic system for a vehicle, the hydraulic system comprising a first electric motor, a second electric motor, a gearbox arranged to be driven by the first and second electric motors, a hydraulic pump arranged to be driven by the gearbox, and a control arrangement configured to individually control the first and second electric motors to either run at a reference speed or to deliver a reference torque and during operation control at least one of the first and second electric motors to deliver a reference torque, wherein the control arrangement is configured to simultaneously control the first motor to run at a reference speed and control the second motor to deliver a reference torque.
2 . The hydraulic system of claim 1 , wherein the control arrangement is configured to simultaneously control the first motor to run at a reference speed and control the second motor to deliver a reference torque.
3 . The hydraulic system of claim 1 , wherein the control arrangement is adapted to control the first and second motors in response to a hydraulic supply request and is configured, based on said hydraulic supply request, to selectively control the first motor to run at a reference speed and the second motor to deliver a reference torque, or control the first motor to deliver a reference torque and the second motor to deliver a reference torque.
4 . The hydraulic system of claim 3 , wherein the control arrangement is configured to control the first motor to run at a reference speed and the second motor to deliver a reference torque in case the hydraulic supply request involves adjusting the hydraulic pump speed, and control the first motor to deliver a reference torque and the second motor to deliver a reference torque in case the hydraulic supply request involves adjusting the hydraulic pump torque.
5 . The hydraulic system of claim 4 , wherein the control arrangement is configured to control the first motor to deliver a reference torque and the second motor to deliver a reference torque in case the desired hydraulic pump speed has remained unchanged for a predetermined duration of time.
6 . The hydraulic system of claim 4 , wherein the control arrangement is connected to an operator input interface and configured to control the first motor to deliver a reference torque and the second motor to deliver a reference torque in case the operator input interface is maneuvered in a manner that is predicted to involve an increase in the desired hydraulic pump torque.
7 . The hydraulic system of claim 1 , wherein the control arrangement comprises a first electronic control unit connected to the first motor and a second electronic control unit connected to the second motor.
8 . The hydraulic system of claim 7 , wherein the first electronic control unit has a faster response time than the second electronic control unit.
9 . The hydraulic system of claim 8 , wherein the first electronic control unit is configured to control the first motor to deliver a reference speed and the second electronic control unit is configured to control the second motor to deliver a reference torque.
10 . The hydraulic system according to claim 7 , wherein the first electronic control unit comprises a first direct current voltage input and a first alternating current voltage output connected to the first motor, and the second electronic control unit comprises a second direct current voltage input and a second alternating current voltage output connected to the second motor.
11 . The hydraulic system of claim 1 , adapted to, when the first motor is controlled to deliver a reference torque and the second motor is controlled to deliver a reference torque, control the first and second motors to deliver essentially equal magnitudes of torques.
12 . The hydraulic system of claim 1 , wherein housings of the first and second motors are attached to a housing of the gearbox and, optionally, a housing of the hydraulic pump is attached to the housing of the gearbox.
13 . The hydraulic system of claim 1 , wherein the first and second motors are arranged to drive the gearbox in parallel.
14 . The hydraulic system of claim 1 , wherein the gearbox is a reduction gearbox.
15 . The hydraulic system of claim 1 , wherein the first and second motors are dimensioned such that operation of both motors is required during nominal operation of the hydraulic system.
16 . A vehicle comprising the hydraulic system of claim 1 , the vehicle optionally being a construction machine or an on-road vehicle.
17 . The vehicle of claim 16 comprising a vehicle electric control unit connected to a first electronic control unit adapted to control the first motor and connected to a second electronic control unit adapted to control the second motor, a battery connected to the first and second electronic control units, and an operator input interface.
18 . A computer-implemented method of operating the hydraulic system according to claim 1 , the method comprising individually controlling the first and second electric motors to either run at a reference speed or to deliver a reference torque wherein, during operation, at least one of the first and second electric motors is controlled to deliver a reference torque.
19 . A computer program product comprising program code for performing, when executed by a processor device, the computer-implemented method of claim 18 .
20 . A non-transitory computer-readable storage medium comprising instructions, which when executed by the processor device, cause the processing circuitry to perform the computer-implemented method of claim 18 .

Description

TECHNICAL FIELD The disclosure relates generally to electric motor control. In particular aspects, the disclosure relates to a hydraulic system for a vehicle, a computer-implemented method of operating a hydraulic system, a computer program product and a non-transitory computer-readable storage medium. The disclosure can be applied to heavy-duty vehicles, such as trucks, buses, and construction equipment, among other vehicle types. Although the disclosure may be described with respect to a particular vehicle, the disclosure is not restricted to any particular vehicle. BACKGROUND Vehicles, in particular heavy-duty vehicles, may comprise hydraulic equipment. For this reason, such vehicles often comprise a hydraulic pump and a means for driving the hydraulic pump. It may be desirable to avoid driving means that in the form of an internal combustion engine for driving the hydraulic pump. SUMMARY According to a first aspect of the disclosure, there is provided a hydraulic system for a vehicle, the hydraulic system comprising a first electric motor, a second electric motor, a gearbox arranged to be driven by the first and second electric motors, a hydraulic pump arranged to be driven by the gearbox, and a control arrangement configured to individually control the first and second electric motors to either run at a reference speed or to deliver a reference torque and during operation control at least one of the first and second electric motors to deliver a reference torque. A technical benefit may include that the two motors may be operated together to drive the hydraulic pump with no or minimum stability issues. Further, using two motors instead of one motor may result in improved hydraulic pump control, lower costs and increased redundancy. Tests have been shown that should both motors simultaneously be controlled to run at a reference speed, there may be stability issues such as resonance. From a cost perspective, it may be beneficial to use large series of relatively small motors, instead of fewer larger motors. Such relatively small motors may find use is as great number of applications, and in some of these one motor may be sufficient whereas other require two or more motors. Optionally, the control arrangement is configured to simultaneously control the first motor to run at a reference speed and control the second motor to deliver a reference torque. A technical benefit may include that a hydraulic supply request may be quickly and reliably delivered by the first and the second motor. Optionally, the control arrangement is adapted to control the first and second motors in response to a hydraulic supply request and is configured, based on said hydraulic supply request, to selectively control the first motor to run at a reference speed and the second motor to deliver a reference torque, or control the first motor to deliver a reference torque and the second motor to deliver a reference torque. A technical benefit may include that the hydraulic system is suited to respond to various hydraulic supply requests. Should there be a request to increase a hydraulic pump speed, tests have shown that it is beneficial to control the first motor to run at a reference speed and the second motor to deliver a reference torque. The first motor may then, completely or essentially completely, act to meet the desired hydraulic pump speed while there is no interference between the motors. Thus, when there is a request to increase a hydraulic pump speed, the motors may deliver different magnitudes of torques. Should there be a request to increase a hydraulic pump torque, tests have shown that it is beneficial to control the first motor to deliver a reference torque and the second motor to deliver a reference torque. The motors may then jointly act to keep the hydraulic pump speed constant while the desired hydraulic pump torque may vary. Optionally, in the latter case the motors may be controlled to deliver essentially equal magnitudes of torques to increase motor life (same wear). Such equal torque distribution may further be beneficial for cooling system design, as both motors may require the same level of cooling. Optionally, the control arrangement is configured to control the first motor to run at a reference speed and the second motor to deliver a reference torque in case the hydraulic supply request involves adjusting the hydraulic pump speed, and control the first motor to deliver a reference torque and the second motor to deliver a reference torque in case the hydraulic supply request involves adjusting the hydraulic pump torque. A technical benefit may include that the hydraulic system is suited to respond to various hydraulic supply requests, as explained in the preceding paragraph. Optionally, the control arrangement is configured to control the first motor to deliver a reference torque and the second motor to deliver a reference torque in case the desired hydraulic pump speed has remained unchanged for a predetermin