Servo-assisted steering arrangement

Claim 2

In a servo-assisted steering arrangement for a vehicle including a servo system comprising: piston and cylinder means for actuating the steering gear of said vehicle; a source of pressure medium; a plurality of valves controlling admission and release of said pressure medium to and from said piston and cylinder means to actuate said piston and cylinder means; electrically actuatable control means for controlling operation of said plurality of valves; and sensing means for sensing actuation of a steering wheel of said vehicle and for providing an electrical control signal for controlling said electrically actuatable control means in response to said actuation of said steering wheel; the improvement wherein said electrically actuatable control means includes pulse generation means for providing a train of output pulses, and switch means responsive to said electrical control signal from said sensing means for causing said train of output pulses to be applied to said valves for actuating same whereby pulsed operation of said valves occurs upon each actuation of said control means.

Claim 3

An arrangement as defined in claim 1, wherein said sensing means comprises a torque sensing element for sensing the torque produced by movement of said steering wheel.

Claim 4

An arrangement as defined in claim 2 comprising further sensing means for measuring the rotary speed of said steering wheel; and wherein said control means is responsive to both said sensing means and said torque sensing element to increase the speed of operation of said piston and cylinder means with increasing torque and increasing rotary speed of said steering wheel.

Claim 5

An arrangement as defined in claim 3, wherein said pulse generator means is variable pulse-pause ratio pulse generator means and control means includes means responsive to both said further sensing means and said torque sensing element for varying said pulse-pause ratio of said pulse generator means.

Claim 6

An arrangement as defined in claim 3 and comprising means for controlling the output of said further sensing means for decreasing the influence of said output of said further sensing means with increasing vehichle speed.

Claim 7

An arrangement as defined in claim 3 and comprising means for controlling the output of said torque sensing element for decreasing the influence of said output of said torque sensing element with increasing vehicle speed.

Claim 8

An arrangement as defined in claim 3 and comprising means for controlling the output of said further sensing means and said torque sensing element for decreasing the influence of said output of said further sensing and said torque sensing element with increasing vehicle speed.

Claim 9

An arrangement as defined in claim 2, wherein said torque sensing element includes means for causing the torque required to be applied to the steering wheel to increase slowly with the turning angles of said steering wheel in a predetermined range about its zero position and for increasing the torque required to be applied to the steering wheel more rapidly with further turning of said steering wheeL.

Claim 10

An arrangement as defined in claim 2, wherein said torque sensing element comprises at least one magnet and a magnetic field-sensitive semiconductor for each sense of rotation of said steering wheel and means for effecting relative movement between said magnet and associated magnetic field sensitive semiconductor when said steering wheel is rotated.

Claim 11

An arrangement as defined in claim 1, wherein said sensing means comprises a rotary movement sensing device for sensing rotary movement of said steering wheel.

Claim 12

An arrangement as defined in claim 1, wherein said plurality of valves comprise electromagnetic valves

Claim 13

An arrangement as defined in claim 11, further comprising a safety circuit including comparison means for determining whether a control signal is present on actuation of said electromagnetic valves and means for switching off said servo system in the absence of said control signal.

Claim 14

An arrangement as defined in claim 11, further comprising a safety circuit including a time element for timing the actuation of said electromagnetic valves and switching off said servo system when said electromagnetic valves are actuated for a predetermined time.

Claim 15

An arrangement as defined in claim 11, further comprising a further pulse generator means for providing an output upon failure of normal operation of a unit of said vehicle, and means for feeding the output of said pulse generator to said electromagnetic valves for rapid alternating control of said steering gear.

Claim 16

An arrangement as defined in claim 11, and comprising sensing means for sensing whether said vehicle is following a predetermined line and means for actuating said electromagnetic valves on deviation from said line to return said vehicle to said line.

Claim 17

An arrangement as defined in claim 11, wherein said sensing means measures the rotary speed of said steering wheel and said control means is responsive to said sensing means for controlling said electromagnetic valves to increase the speed of operation of said piston and cylinder means with increasing rotary speed of said steering wheel.

Claim 18

An arrangement as defined in claim 16, wherein said pulse generator means includes means responsive to said sensing means for varying the pulse pause ratio of said train of output pulses.

Claim 19

An arrangement as defined in claim 11, and comprising a common return line for said pressure medium, two two-way electromagnetic valves forming said electromagnetic valves and a further electromagnetic valve in said return line for actuation with either of said two two-way electromagnetic valves.

Claim 20

An arrangement as defined in claim 1, wherein said pulse generator means comprises a variable output pulse generator whose pulse-pause ratio is dependent on rotation of said steering wheel so as to increase said pulse-pause ratio with increased rotation of said steering wheel.

Claim 21

An arrangement as defined in claim 1, wherein said control means includes ratio control means for controlling the pulse pause ratio of said pulse generator means in dependence on vehicle speed so as to decrease said pulse-pause ratio with increasing vehicle speed.

Claim 22

An arrangement as defined in claim 7, and comprising a cylinder in said piston and cylinder means, a piston in said cylinder, a first chamber of said cylinder on one side of said piston a second chamber of said cylinder on the other side of said piston, a return line for said pressure medium, and two throttles connected between said first and second chambers and said return line.

Claim 23

An arrangement as defined in claim 21, and further comprising a unidirectional valve in said return line operable at a predetermined pressure to permit flow of the pressure medium toward said source.

Claim 24

An arrangement as defined in claim 21, and comprising a respective unidirectional valve connected between each said first and second chambers and said return line and operable at a predetermined pressure differenCe to open towards said chambers.

Claim 25

An arrangement as defined in claim 7, and further comprising operation control means for permitting operation of said electrically actuatable control means only below a predetermined vehicle speed.

Claim 26

An arrangement as defined in claim 24, wherein said operation control means comprises a gate and a threshold.

Claim 27

An arrangement as defined in claim 24, and comprising varying means for varying said predetermined vehicle speed upwards with certain parameters of operation of said steering wheel.

Claim 28

An arrangement as defined in claim 26, and comprising varying means for varying said predetermined vehicle speed upwards in response to a high torque of said steering wheel.

Claim 29

An arrangement as defined in claim 26, and comprising varying means for varying said predetermined vehicle speed upwards in response to a large rotary angle of said steering wheel.

Claim 30

An arrangement as defined in claim 26, and comprising varying means for varying said predetermined vehicle speed upwards in response to a high torque and a large rotary angle of said steering wheel.

Claim 31

An arrangement as defined in claim 26, wherein said operation control means comprises a gate and a threshold and said varying means comprises means for displacement of the threshold value of said threshold.

Claim 32

An arrangement as defined in claim 7, and comprising an intergral unit containing steering dampers and said piston and cylinder means.

Claim 33

An arrangement as defined in claim 7, and comprising an intergral unit containing steering dampers, said piston and cylinder means and said steering gear.

Claim 34

An arrangement as defined in claim 1 and comprising two pressure sensing elements in brake lines to two steered wheels of said vehicle operated on by an anti-lock control system with separate control for said two steered wheels, first comparison means responsive to said pressure sensing elements for comparing brake pressures in said brake lines to said two steered wheels and for producing a deviation signal elements brake pressures are different, means for producing a deflection signal representative in magnitude and sense of deflection of said steered wheels, second comparison means dor comparing said deflection signal with said deviation signal and means for controlling said electromagnetic valves when said comparison means detects a deviation from a predetermined correlation to vary said steering gear accordingly.

Claim 35

In a servo-assisted steering arrangement for a vehicle comprising: piston and cylinder means for actuating the steering gear of said vehicle; a source of pressure medium; a plurality of valves controlling admission and release of said pressure medium to and from said piston and cylinder means to actuate said piston and cylinder means; electrically actuatable control means for controlling operation of said plurality of valves and sensing means for sensing actuation of a steering wheel of said vehicle and for providing an electrical control signal for controlling said electrically actuatable control means in response to said actuation of said steering wheel; the improvement wherein said sensing means includes a torque sensing element for sensing the torque produced by movement of said steering wheel, and wherein said torque sensing element comprises at least one magnet and a magnetic field-sensitive semiconductor for each sense of rotation of said steering wheel and means for effecting relative movement between said magnet and magnetic field sensitive semiconductor when said steering wheel is rotated.

Claim 36

In a servo-assisted steering arrangement for a vehicle comprising: piston and cylinder means for actuating the steering gear of said vehicle; a source of pressure medium; a plurality of valves controlling admission and release of said pressure medium to and from said piston and cylinder means to actuate said piston and cylinder means; electrically actuatable control means for controlling operation of said plurality of valves and sensing means for sensing actuation of a steering wheel of said vehicle and for providing an electrical control signal for controlling said electrically actuatable control means in response to said actuation of said steering wheel; the improvement wherein said sensing means includes a torque sensing element for sensing the torque produced by movement of said steering wheel, and wherein said torque sensing element comprises at least one magnet and a magnetic field-sensitive semiconductor for each sense of rotation of said steering wheel and means for effecting relative movement between said magnet and magnetic field sensitive semiconductor when said steering wheel is rotated.

Claim 37

In a servo-assisted steering arrangement for a vehicle including: piston and cylinder means for actuating the steering gear of said vehicle; a source of pressure medium; a plurality of electromagnetic valves controlling admission and release of said pressure medium to and from said piston and cylinder means to actuate said piston and cylinder means; electrically actuatable control means for controlling operation of said plurality of Valves; and sensing means for sensing actuation of a steering wheel of said vehicle and for providing an electrical control signal for controlling said electrically actuatable control means in response to said actuation of said steering wheel; the improvement comprising a common return line for said pressure medium, two two-way electromagnetic valves forming said electromagnetic valves, and a further electromagnetic valve in said return line and controlled by said control means for actuation with either of said two two-way electromagnetic valves.

Claim 38

In a servo-assisted steering arrangement for a vehicle including: piston and cylinder means for actuating the steering gear of said vehicle; a source of pressure medium; a plurality of electromagnetic valves controlling admission and release of said pressure medium to and from said piston and cylinder means to actuate said piston and cylinder means; electrically actuatable control means for controlling operation of said plurality of Valves; and sensing means for sensing actuation of a steering wheel of said vehicle and for providing an electrical control signal for controlling said electrically actuatable control means in response to said actuation of said steering wheel; the improvement comprising a common return line for said pressure medium, two two-way electromagnetic valves forming said electromagnetic valves, and a further electromagnetic valve in said return line and controlled by said control means for actuation with either of said two two-way electromagnetic valves.

Claim 39

A servo-assisted steering arrangement for a vehicle comprising: piston and cylinder means for actuating the steering gear of said vehicle; a source of pressure medium; a plurality of electromagnetic valves controlling admission and release of said pressure medium to and from said piston and cylinder means to actuate said piston and cylinder means; electrically actuatable control means for controlling operation of said plurality of valves; sensing means for sensing actuation of a steering wheel of said vehicle and for providing an electrical control signal for controlling said electrically actuatable control means in response to said actuation of said steering wheel; two pressure sensing elements in the brake lines to the two steered wheels of said vehicle operated on by an anti-lock control system with separate control for said two steered wheels; first comparision means responsive to said pressure sensing elements for comparing brake pressure in said brake lines to said two steered wheels and for producing a deviation signal when said brake pressures are different; means for producing a deflection signal representatibe in magnitude and sense of deflection of said steered wheels; second comparison means for comparing said deflection signal with said deviation signal; and means for controlling said electromagnetic valves when said comparison means detects a deviation from a predetermined correlation to vary said steering gear accordingly.

Claim 40

A servo-assisted steering arrangement for a vehicle comprising: piston and cylinder means for actuating the steering gear of said vehicle; a source of pressure medium; a plurality of electromagnetic valves controlling admission and release of said pressure medium to and from said piston and cylinder means to actuate said piston and cylinder means; electrically actuatable control means for controlling operation of said plurality of valves; sensing means for sensing actuation of a steering wheel of said vehicle and for providing an electrical control signal for controlling said electrically actuatable control means in response to said actuation of said steering wheel; two pressure sensing elements in the brake lines to the two steered wheels of said vehicle operated on by an anti-lock control system with separate control for said two steered wheels; first comparision means responsive to said pressure sensing elements for comparing brake pressure in said brake lines to said two steered wheels and for producing a deviation signal when said brake pressures are different; means for producing a deflection signal representatibe in magnitude and sense of deflection of said steered wheels; second comparison means for comparing said deflection signal with said deviation signal; and means for controlling said electromagnetic valves when said comparison means detects a deviation from a predetermined correlation to vary said steering gear accordingly.