Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D5/00—Power-assisted or power-driven steering
  • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
  • B62D5/20—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application
  • B62D5/24—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application for worm type
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D5/00—Power-assisted or power-driven steering
  • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
  • B62D5/065—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle characterised by specially adapted means for varying pressurised fluid supply based on need, e.g. on-demand, variable assist

Definitions

• the present invention relates to the field of electronically controlled electrohydraulic steering systems for motor vehicles. It will be particularly interesting for commercial vehicles, trucks or coaches.
• This electrohydraulic steering solution combines the advantages of electronically controlled demand - driven power steering and a robust hydraulic actuation system.
• An important advantage of this solution over hydraulic assist systems is independence from the propulsion engine of the vehicle.
• the power available for the assistance is independent of the engine speed and the cut that it has no detrimental effect on the operation of the assistance to the direction.
• Electrohydraulic solutions also save fuel and reduce carbon dioxide emissions.
• this solution makes it possible to answer situations requiring high powers of assistance, in particular for trucks or coaches.
• US Pat. No. US8584791 is known describing a hydraulic power assist steering device for a vehicle equipped with a hydraulic cylinder. It includes a flow control valve, a steering torque sensor, a steering angle sensor, a vehicle speed sensor, and a computer.
• the flow control valve changes the hydraulic fluid supply / discharge amount for the hydraulic cylinder.
• a steering shaft with a steering wheel (16) is connected to an input member of a steering transmission (2),
• an output member of the steering transmission is connected to the wheels to be directed from the motor vehicle
• working chambers of a booster of a force amplification device can receive pressurized fluid from a servomotor by means of intermediate of a steering valve when a rotational torque occurs in the region of the steering shaft or the input member
• at least one sensor for detecting an angle of rotation and a rotational torque is arranged on the steering shaft
• a sensor for the detection of a steering angle is arranged on a part of the steering gear, in particular on the output member or on the input member
• the size and direction of the hydraulic assistance that the return of the wheels to be steered are controlled by a common electronically controlled electromagnetic valve, and in that for the detection of the steering force, there is only one sensor of direction and / or torque.
• the European patent application is also known
• EP1213205 describing another example of a steering device externally actuated according to the "steer-by-wire" steering principle, comprising a hydraulic control valve for controlling a hydraulic steering actuator (13) and an electric motor for providing the torque controlling the control valve, and also comprising a target value detector for a steering handle which provides set values for a control circuit, wherein the steering actuator is disposed in the adjustment section, on which a real value detector is provided a gearbox being disposed in the torque transfer section from the electric motor between the electric motor and the control valve, and the torque transfer section being uncoupled mechanically continuously from the steering lever.
• the control valve is disposed in the torque transfer section between the reducer and the hydraulic steering actuator.
• the electromechanical steering function is exerted through the torque transfer section and the hydraulic steering function that can be exerted by the control valve and the steering actuator mutually support each other in normal mode and are controlled in such a way that that the electromechanical steering function acts in emergency mode as a fallback level for the hydraulic steering function.
• the electric motor and the gearbox are sized accordingly so that they are able, in the event of a failure of the hydraulic steering function, to provide a prescribed minimum steering performance.
• the hydraulic circuit also has increased risks of leaks from the hydraulic system.
• pressurized fluid must be cooled because of the heating which occurs during its circulation.
• the invention relates, according to its more general meaning, to an electronically controlled electrohydraulic steering system for vehicles comprising a steering column provided with a torque sensor located upstream of a steering box, said steering gear containing a worm gear in rotation a toothed sector shaft) controlling the angular displacement of a steering rod, the system further comprising a pump driven by an electric motor controlling the circulation of a fluid in the steering box characterized in that it comprises in addition, a computer comprising an input for the signals delivered by said torque sensor and / or the signals delivered by an autonomous driving system and controlling the flow rate, the direction of rotation and the instantaneous volume of said electric pump, the hydraulic circuit as well as formed operating in a closed circuit.
• the system according to the invention controls the operation of the electric pump only when the intervention of an assistance is necessary. During the rest of the time, the motor is not powered or is simply held in position, which reduces the consumption of the system compared to the solutions of the prior art.
• the electrohydraulic steering system assisted according to the invention comprises a connecting conduit of the two chambers provided with a valve held in the closed position (for example by an electrical signal) and driven in the open position in case of electrical failure.
• the pumping circuit is short-circuited and parasitic forces are minimized to allow manual forced operation of the steering.
• the computer controls the direction as a function of information independent of the steering column and / or in the absence of a steering column.
• the system according to the invention thus makes it possible to carry out: - simple steering assistance, with steering column
• said worm drives said toothed sector shaft via a piston nut forming two chambers, said electric pump ensuring the transfer of fluid between said two chambers of the hydraulic circuit.
• the system comprises a connecting conduit of the two chambers provided with a valve held in the closed position and driven in the open position in case of failure of the assistance system.
• the system is therefore devoid of torsion shaft mechanically controlling the transfer of fluid, unlike systems of the state of the art where the torsion shaft for the circulation of the fluid is essential and entails additional cost and complexity.
• the present system may advantageously be devoid of mechanical link between the steering column and the steering box.
• the computer can control the direction based on information independent of the steering column and / or in the absence of steering column.
• the piston-nut is devoid of hydraulic function, the axis of the worm being rotated by a rotary hydraulic motor powered by the electric hydraulic pump receiving instructions for controlling the computer.
• the axis of the sector gear is rotated by a rotary hydraulic actuator powered by the electric hydraulic pump receiving instructions for controlling the computer (5).
• the piston-nut is not used and the worm directly rotates the toothed sector, the axis of said worm being rotated by a rotary hydraulic motor powered by the pump electric hydraulic receiving his instructions for controlling the calculator.
• the worm directly rotates the toothed sector, the axis of said hydraulic sector being rotated by a rotary hydraulic actuator powered by the electric hydraulic pump receiving his instructions for controlling the calculator.
• the invention also proposes a steering box for an electronically controlled electrohydraulic steering system for vehicles comprising a steering column provided with a torque sensor located upstream of a steering box, the system further comprising a pump electrical control controlling the transfer of fluid in two chambers of said steering box characterized in that it is constituted by a hollow body inside which moves a piston between two chambers of variable volume depending on the volume of fluid injected or discharged by said pump, said piston cooperating with a worm driving a toothed sector shaft controlling the angular displacement of a steering rod.
• a pump electrical control controlling the transfer of fluid in two chambers of said steering box characterized in that it is constituted by a hollow body inside which moves a piston between two chambers of variable volume depending on the volume of fluid injected or discharged by said pump, said piston cooperating with a worm driving a toothed sector shaft controlling the angular displacement of a steering rod.
• FIG. 1 represents a schematic view of a system according to the invention
• FIG. 2 represents a schematic view of the steering box
• FIG. 3 represents a schematic view of the assistance system according to a particular embodiment in which the piston-nut has no hydraulic function
• FIG. 4 represents a schematic view of the assistance system according to another particular embodiment in which the piston-nut is devoid of hydraulic function
• FIG. 5 represents a schematic view of the assistance system according to a particular embodiment with a direct connection between the worm and the toothed sector
• Figure 6 shows a schematic view of the assistance system according to another particular embodiment with a direct connection between the worm and the toothed sector.
• the electrohydraulic power steering system described by way of example in the following comprises a steering box (1) whose input shaft is mechanically coupled to the steering column (2) driven by the steering wheel (3).
• a torque sensor (4) is placed on the steering column (2) between the steering wheel (3) and the steering gear (1).
• This torque sensor (4) provides a signal representative of the forces exerted by the driver on a computer (5).
• This calculator (5) receives data from various sensors and equipment, for example a steering column position sensor, a vehicle speed sensor, or a driver selected driving mode. It can also receive data from an autonomous driving system (13).
• the computer (5) supplies the control signals to the motor (6) of a reversible pump (7) to control the direction of rotation of the motor, the angular displacement and the speed.
• This pump (7) feeds the steering box (1) by two ducts (8, 9) supplying opposite chambers provided in the steering box.
• the pump controls the flow of fluid between these two ducts forming a closed circuit, in both directions, with a flow and a direction determined by the computer (5) controlling the operation of the electric motor (6) of the pump (7).
• a fluid reservoir (11) supplies the closed circuit via a non-return valve (12).
• the two outputs of the pump are connected by an exchanger (10) which is normally closed and which has an open position in case of electrical failure.
• an exchanger 10 which is normally closed and which has an open position in case of electrical failure.
• Figure 2 shows a sectional view of an exemplary steering box (1).
• This body delimiting a cylindrical volume inside which moves a piston (20).
• This body has two orifices connected to the conduits (8, 9) for circulating the fluid under the control of the pump (7). These openings (8, 9) open into two chambers respectively (18, 19) on either side of the piston (20). Depending on the direction of circulation of the pump and the pressure, the piston is moved inside the sealed body (17).
• the piston (20) is provided with a rack (21), which will transmit, during its displacement, the movement to the toothed sector (22) thus transforming the translation of the rack (21), in rotation of the steering rod (23) driven by a partially toothed wheel.
• the toothed sector (22) is connected to the connecting rod (23) which transmits the control force to the wheelhouse.
• the unattended operation is made possible, although requiring a greater effort on the part of the driver through the exchanger (10) which opens and bypasses the pumping circuit, canceling the hydraulic pressure in the steering box (1). It goes without saying that the unattended mode is a backup mode.
• FIG. 3 diagrammatically shows an embodiment where the piston nut (20) has no hydraulic function and the axis of the worm (25) is directly rotated by a hydraulic motor (14).
• This hydraulic motor (14) is powered by the hydraulic circuit controlled by the pump (7).
• the hydraulic motor (14) can perform several turns corresponding to the number of revolutions of the steering column.
• This device makes it possible to simplify the steering box and to deport the assistance circuit as well as to use a standard hydraulic motor.
• FIG. 4 diagrammatically shows another embodiment in which the piston nut (20) has no hydraulic function and the toothed sector (22) is directly rotated by a hydraulic actuator (15).
• This hydraulic actuator (15) is fed by the hydraulic circuit controlled by the pump (7).
• the hydraulic actuator (15) has a limited angular stroke (typically a few degrees to a few tens of degrees) corresponding to the maximum amplitude of the steering rod (23).
• FIG. 5 diagrammatically shows an embodiment where the steering box (1) is devoid of a piston nut, the worm (25) being in direct mechanical relation with the toothed sector (22) and where the axle the worm (25) is directly rotated by a hydraulic motor (14).
• This hydraulic motor (14) is powered by the hydraulic circuit controlled by the pump (7).
• the hydraulic motor (14) can perform several turns corresponding to the number of revolutions of the steering column.
• FIG. 6 diagrammatically shows another embodiment in which the steering box (1) is devoid of a piston nut, the worm (25) being in direct mechanical relation with the toothed sector (22) and in which the sector toothed gear (22) is directly rotated by a hydraulic actuator (15).
• This hydraulic actuator (15) is fed by the hydraulic circuit controlled by the pump (7).
• the hydraulic actuator (15) has a limited angular stroke (typically a few degrees to a few tens of degrees) corresponding to the maximum amplitude of the steering rod (23).
• This device simplifies the steering box, removing the piston nut, and deport the assistance circuit and use a standard hydraulic actuator. It should be noted that the latter embodiment will be particularly interesting by the easier realization of a hydraulic actuator compared to a hydraulic motor.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Power Steering Mechanism (AREA)
• Steering Control In Accordance With Driving Conditions (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=57906705

Family Applications (1)

Country Status (3)

Families Citing this family (3)

Citations (1)

Family Cites Families (6)

• 2016
  • 2016-09-19 FR FR1658720A patent/FR3056181B1/fr active Active
• 2017
  • 2017-09-08 EP EP17767787.9A patent/EP3515792A1/de not_active Withdrawn
  • 2017-09-08 WO PCT/EP2017/072653 patent/WO2018050568A1/fr not_active Ceased

Patent Citations (1)

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