Hydrostatic steering arrangement
A steering arrangement for a vehicle includes: a hydrostatic steering unit provided with two work ports, a high-pressure port, a low-pressure port, a main branch of the flow arranged between the work ports and the high-pressure port and comprising a dosing device, and an amplification branch arranged between the work ports and the high-pressure port, in parallel with the dosing device, and comprising a flow-rate regulating device of the electrically actuated type, a steering shaft provided with a first end adapted for being connected to a steering member and a second end adapted for being connected to the hydrostatic steering unit, an electric motor configured to set the steering shaft in rotation, and an electronic control unit configured to actuate the flow-rate regulating device as a function of a parameter indicative of an operating condition of the vehicle.
1. A steering arrangement ( 10 ) for a vehicle ( 1 ) comprising:
a hydrostatic steering unit ( 65 ) provided with two work ports ( 80 , 85 ), a high-pressure port ( 70 ), a low-pressure port ( 75 ), a main branch of the flow ( 95 ) arranged between the work ports ( 80 , 85 ) and the high-pressure port ( 70 ) and comprising a dosing device ( 90 ), and an amplification branch ( 120 ) arranged between the work ports and the high-pressure port, in parallel to the dosing device, and comprising a flow-rate regulating device ( 125 ) of the electrically actuated type,
a steering shaft ( 60 ) provided with a first end adapted for being connected to a steering member ( 55 ) and a second end adapted for being connected to the hydrostatic steering unit ( 65 ),
an electric motor ( 185 ) configured to set the steering shaft ( 60 ) in rotation, and
an electronic control unit ( 220 ) configured to actuate the flow-rate regulating device ( 125 ) as a function of a parameter indicative of an operating condition of the vehicle.
2. The steering arrangement ( 10 ) according to claim 1 , wherein the flow-rate regulating device ( 125 ) is configured to regulate the flow rate in the amplification branch ( 120 ) within a range of flow rate values comprised between a minimum flow rate value in the amplification branch and a maximum flow rate value in the amplification branch, and the electronic control unit ( 220 ) is configured to actuate the flow-rate regulating device ( 125 ) along said range as a function of a parameter indicative of an operating condition of the vehicle ( 1 ).
3. The steering arrangement ( 10 ) according to claim 1 , wherein the electronic control unit ( 220 ) is configured to actuate the electric motor ( 185 ) as a function of the parameter indicative of an operating condition of the vehicle ( 1 ) so as to provide a haptic feedback to the user through a torque generated on the steering shaft ( 60 ).
4. The steering arrangement ( 10 ) according to claim 3 , further comprising a rotation sensor configured to measure a parameter indicative of a rotation angle ( 200 , 205 , 210 ) of the steering shaft ( 60 ) and wherein the electronic control unit ( 220 ) is configured to actuate the electric motor ( 185 ) as a function of the parameter indicative of an operating condition of the vehicle ( 1 ) and as a function of said parameter indicative of a rotation angle of the steering shaft ( 60 ), so as to provide a haptic feedback to the user through a torque generated on the steering shaft ( 60 ).
5. The steering arrangement ( 10 ) according to claim 1 , wherein the electronic control unit ( 220 ) is configured to select, as a function of the parameter indicative of an operating condition of the vehicle ( 1 ), a management algorithm among a plurality of management algorithms of the ratio between the flow rate that passes through the amplification branch ( 120 ) and the flow rate that passes through the main branch ( 95 ), and to actuate the flow-rate regulating device ( 125 ) according to said management algorithm.
6. The steering arrangement ( 10 ) according to claim 5 , wherein said plurality of management algorithms comprises a management algorithm in which the flow-rate regulating device ( 125 ) is actuated to change the flow rate in the amplification branch ( 120 ) within a sub-range, of the total range of the flow-rate regulating device ( 125 ), having extension of 9/10 of the total range and comprising the maximum flow rate value in the amplification branch ( 120 ).
7. The steering arrangement ( 10 ) according to claim 6 , wherein when the electronic control unit actuates the flow-rate regulating device according to said management algorithm, the electronic control unit is configured to actuate the electric motor so as to generate a torque on the steering shaft oriented in the same direction of rotation in which the user actuates the steering member.
8. The steering arrangement ( 10 ) according to claim 5 , wherein said plurality of management algorithms comprises a management algorithm in which the flow-rate regulating device ( 125 ) is actuated within a sub-range of the total range of the flow-rate regulating device ( 125 ) having extension comprised between 4/10 and 5/10 of the total range and comprising the minimum flow rate value in the amplification branch ( 120 ).
9. The steering arrangement ( 10 ) according to claim 1 , wherein the parameter indicative of the operating condition can be at least one among an input provided by a manual interface device and a value of a parameter indicative of an operating condition of the vehicle measured by a sensor of the vehicle, said sensor being one between an inertial platform adapted for measuring the instantaneous accelerations of the vehicle on at least three mutually perpendicular axes and a sensor configured to measure a parameter indicative of the speed of movement of the vehicle, wherein said sensor ( 300 ) is operatively connected to the electronic control unit ( 220 ) and is configured to detect the parameter indicative of the operating condition of the vehicle ( 1 ) and in which the electronic control unit ( 220 ) is configured to automatically actuate the flow-rate regulating device ( 125 ) as a function of the parameter detected by the sensor.
10. The steering arrangement ( 10 ) according to claim 9 , wherein when the electronic control unit actuates the flow-rate regulating device according such management algorithm, the electronic control unit is also configured to actuate the electric motor so as to generate a torque on the steering shaft, oriented in an opposite direction of rotation with respect to that in which the user actuates the steering member.
11. Vehicle ( 1 ) comprising
the steering arrangement ( 10 ) according to claim 1 ,
a pair of steered wheels ( 5 ),
a rotation sensor ( 200 , 205 , 210 ) configured to measure a parameter indicative of a rotation angle of the steering shaft ( 60 ),
a steering sensor ( 215 ) configured to measure a parameter indicative of a steering angle of the steered wheels ( 5 ), wherein the electronic control unit ( 220 ) is operatively connected to the steering sensor ( 215 ) and to the rotation sensor ( 200 , 205 , 210 ) and is configured to actuate the flow-rate regulating device ( 125 ) as a function of a parameter indicative of an operating condition of the vehicle ( 1 ) and of the ratio between the angle of rotation of the steering shaft ( 60 ) and the steering angle of the steered wheels ( 5 ).
12. The vehicle ( 1 ) according to claim 11 , wherein the electronic control unit ( 220 ) comprises a relationship algorithm such that each steering angle value of the steered wheels corresponds to a rotation angle value of the steering shaft, and is configured to compare the value of the parameter indicative of the steering angle of the steered wheels ( 5 ) with the value of the parameter indicative of a rotation angle of the steering shaft ( 60 ) and, when the comparison between such parameters returns a value that differs from the relationship values between angles defined by the relationship algorithm, is configured to actuate the flow-rate regulating device ( 125 ) so as to change the flow rate that flows in the amplification branch until the comparison of the value of the parameter indicative of the steering angle of the steered wheels ( 5 ) with the value of the parameter indicative of a rotation angle of the steering shaft ( 60 ) returns the value provided for by the relationship algorithm.
13. The vehicle ( 1 ) according to claim 11 , wherein the electronic control unit ( 220 ) is configured to actuate the electric motor ( 185 ) so as to drive the vehicle ( 1 ) along a predetermined path and to actuate the flow-rate regulating device ( 125 ) so that the flow rate value in the amplification branch ( 120 ) is around the maximum flow rate value in the amplification branch ( 120 ), when the electronic control unit ( 220 ) actuates the electric motor ( 185 ) to drive the vehicle along the predetermined path.