Auxiliary power steering system

Claim 2

In a booster power steering system utilizing a pressure storage reservoir as a pressure fluid source, the combination which comprises a double acting servo cylinder having a reciprocal piston therein and a servo cylinder pressure chamber at each end of said piston; manually operable valve means and flow passage means for connecting said storage reservoir to said chambers to selectively pressurize either of said chambers with operating pressure from said reservoir; said valve means having road reaction means for effecting simulated steering resistance; and force limiting means for overcoming said simulated steering resistance at a predeterMined limit thereof responsive to operating pressure in said valve means; said valve means comprising a respective valve for each pressure chamber; said road reaction means comprising each said valve having a piston portion and a chamber and flow passage means whereby said chambers receive said operating pressure to act against the respective valve in a direction opposite to the opening direction thereof for effecting simulated steering resistance; said force limiting means comprising respective pressure operated pistons and flow passage means whereby said pistons are exposed to operating pressure controlled by each said valve; a respective prestressed spring against which each said pressure operable piston is movable in response to a predetermined pressure, and abutment means movable by an operator for opening either of said valves to pressurize a respective chamber and disposed to be actuated by either of said pressure operated pistons of said force limiting means in a direction to aid valve opening upon said predetermined pressure acting on either of said pistons.

Claim 3

In a booster power steering system as set forth in claim 1, said valve means comprising a piston valve operable by said abutment means to selectively open either of said valves and flow conducting passages for pressure feed to said valves whereby opening one of said valves effects pressure feed to said piston valve and thence to respective servo cylinder chambers; including additional flow passages from said piston valve for exhaust from either of said chambers when the other chamber is pressurized; said abutment means engaging said piston valve for movement thereof; wherein one said valve is disposed to be engaged to be opened by movement of said piston valve in one direction and the other said valve is disposed to be engaged by movement of said piston valve in the other direction.

Claim 4

In a booster power steering system as set forth in claim 2, each said valve having a valve head, and a steering control spindle having a sleeve fixed therein and having valve seats against which respective valve heads seat in opposite directions; respective springs for effecting seating of said valve heads; said piston valve being intermediate said valves for actuating engagement thereof upon movement of said piston valve; means carried by said steering control spindle to be engaged by said abutment means so as to be rotated thereby; and means intermediate said steering control spindle and said piston for actuating said piston upon rotation of said spindle.

Claim 5

In a booster power steering system as set forth in claim 3; a cap member at each end of said sleeve effecting a respective chamber of said road reaction means, the said piston portions of said valves being disposed therein; said valve heads having effective areas less than the effective areas of respective piston portions whereby a closing biasing force is effected on said valves; said valve means flow passage means comprising grooves in respective valve bodies intermediate the valve head and piston portion of each valve and connected to operating pressure whereby said biasing closing force is effected for each said valve and whereby said operating pressure is available for steering control in said valve means.

Claim 6

In a booster steering system as set forth in claim 4, said flow passage means comprising said sleeve and said piston valve having respective grooves coacting with respective grooves in said valves to effect flow passages when said piston valve is actuated to open one of said valves; said flow passage means further comprising passages in said steering control spindle communicating through said valve grooves to conduct flow to and from said servo cylinder pressure chambers for supply and exhaust of pressure fluid.

Claim 7

In a booster steering system as set forth in claim 4, said piston valve having end bores and each said valve having a hollow tubular extension slidable in a respective end bore, and efFecting communication with the respective road reaction means chamber; a respective passage through said piston valve from each said end bore to the exterior of said piston valve and communicating via passages of said flow passage means to receive operating pressure when a respective valve is open for pressurizing respective road reaction chambers.

Claim 8

In a booster steering system as set forth in claim 3, said valve heads being conical.

Claim 9

In a booster steering system as set forth in claim 3, said piston valve having end bores; each said valve having a hollow tubular extension slidably extending into a respective end bore of said piston valve and a spring in each bore bearing against the respective extension.

Claim 10

In a booster power steering system utilizing a pressure storage reservoir as a pressure fluid source, the combination which comprises a double acting servo cylinder having a reciprocal piston therein and a servo cylinder pressure chamber at each end of said piston; manually operable valve means and flow passage means for connecting said storage reservoir to said chambers to selectively pressurize either of said chambers with operating pressure from said reservoir; said valve means having road reaction means for effecting simulated steering resistance; and force limiting means for overcoming said simulated steering resistance at a predetermined limit thereof responsive to operating pressure in said valve means; a control valve spindle having a pair of parallel bores; said valve means being disposed in one said bore and said force limiting means being disposed in the other of said bores; each said latter means having components for reciprocal motion; said manually operable means comprising a steering shaft having a pair of abutment pins wherein one said pin engages the reciprocal components of said valve means for operation thereof and the other said pin engages the reciprocal components of said force limiting means to be acted against thereby in a direction to aid the application of manual force.

Claim 11

In a booster power steering system utilizing a pressure storage reservoir as a pressure fluid source, the combination which comprises a double acting servo cylinder having a reciprocal piston therein and a servo cylinder pressure chamber at each end of said piston; manually operable valve means and flow passage means for connecting said storage reservoir to said chambers to selectively pressurize either of said chambers with operating pressure from said reservoir; said valve means having road reaction means for effecting simulated steering resistance; and force limiting means for overcoming said simulated steering resistance at a predetermined limit thereof responsive to operating pressure in said valve means; a control valve spindle having a pair of parallel bores; said valve means being disposed in one said bore and said force limiting means being disposed in the other of said bores; each said latter means having components for reciprocal motion; said manually operable means comprising a steering shaft having a pair of abutment pins wherein one said pin engages the reciprocal components of said valve means for operation thereof and the other said pin engages the reciprocal components of said force limiting means to be acted against thereby in a direction to aid the application of manual force.

Claim 12

In a booster steering system as set forth in claim 8, including flow passages intermediate said valve means and said force limiting means; said force limiting means having pressure operable pistons for respective directions of force application and disposed to be pressurized by the pressure in said valve means; prestressed springs for respective pistons to maintain said pistons against effecting aid until pressure thereon overcomes the degree of prestress in respective springs; wherein the functioning of said pistons occurs at less than operating pressure in said valve means, predetermined by the degree of spring prestress and the effective area of said pistons.

Claim 13

In a booster power steering system utilizing a pressure storage reservoir as a pressure fluid source, the combination which comprises a double acting servo cylinder having a reciprocal piston therein and a servo cylinder pressure chamber at each end of said piston; manually operable valve means and flow passage means for connecting said storage reservoir to said chambers to selectively pressurize either of said chambers with operating pressure from said reservoir; said valve means having road reaction means for effecting simulated steering resistance; and force limiting means for overcoming said simulated steering resistance at a predetermined limit thereof responsive to operating pressure in said valve means; said valve means comprising a pair of valves for respective steering directions; and further comprising a piston valve engageable at its ends with a respective valve for opening thereof and being connected with said manually operable means for actuation; said flow passage means comprising passages for pressure fluid to said valves and passages for communicating pressure fluid from either said valves to said piston valve and passages from said piston valve to each said pressure chamber for pressurizing either pressure chamber of said servo cylinder while the oTher said pressure chamber is being exhausted; and a clearance intermediate the ends of said piston valve and the respective valves to delay pressurizing of either chamber until exhaust communication from that chamber is cut off; said piston valve being normally positioned so that both pressure chambers are pressureless and connected to exhaust whereby flow may take place between chambers; said flow passage means including passages controlled by said piston valve for effecting simultaneous exhaust communication for said pressure chambers.

Claim 14

In a booster power steering system utilizing a pressure storage reservoir as a pressure fluid source, the combination which comprises a double acting servo cylinder having a reciprocal piston therein and a servo cylinder pressure chamber at each end of said piston; manually operable valve means and flow passage means for connecting said storage reservoir to said chambers to selectively pressurize either of said chambers with operating pressure from said reservoir; said valve means having road reaction means for effecting simulated steering resistance; and force limiting means for overcoming said simulated steering resistance at a predetermined limit thereof responsive to operating pressure in said valve means; said valve means comprising a pair of valves for respective steering directions; and further comprising a piston valve engageable at its ends with a respective valve for opening thereof and being connected with said manually operable means for actuation; said flow passage means comprising passages for pressure fluid to said valves and passages for communicating pressure fluid from either said valves to said piston valve and passages from said piston valve to each said pressure chamber for pressurizing either pressure chamber of said servo cylinder while the oTher said pressure chamber is being exhausted; and a clearance intermediate the ends of said piston valve and the respective valves to delay pressurizing of either chamber until exhaust communication from that chamber is cut off; said piston valve being normally positioned so that both pressure chambers are pressureless and connected to exhaust whereby flow may take place between chambers; said flow passage means including passages controlled by said piston valve for effecting simultaneous exhaust communication for said pressure chambers.

Claim 15

In a booster power steering system utilizing a pressure storage reservoir as a pressure fluid source, the combination which comprises a double acting servo cylinder having a reciprocal piston therein and a servo cylinder pressure chamber at each end of said piston; manually operable valve means and flow passage means for connecting said storage reservoir to said chambers to selectively pressurize either of said chambers with operating pressure from said reservoir; said valve means having road reaction means for effecting simulated steering resistance; and force limiting means for overcoming said simulated steering resistance at a predetermined limit thereof responsive to operating pressure in said valve means; said force limiting means comprising a pair of axially aligned pistons and a prestressed spring in each piston compressible thereby; said abutment means comprising a member intermediate said springs actuatable by either piston upon a predetermined pressure being exerted thereon; and passage means connecting said valve means with said pistons for communicating operating pressure thereto.

Claim 16

In a booster power steering system utilizing a pressure storage reservoir as a pressure fluid source, the combination which comprises a double acting servo cylinder having a reciprocal piston therein and a servo cylinder pressure chamber at each end of said piston; manually operable valve means and flow passage means for connecting said storage reservoir to said chambers to selectively pressurize either of said chambers with operating pressure from said reservoir; said valve means having road reaction means for effecting simulated steering resistance; and force limiting means for overcoming said simulated steering resistance at a predetermined limit thereof responsive to operating pressure in said valve means; said force limiting means comprising a pair of axially aligned pistons and a prestressed spring in each piston compressible thereby; said abutment means comprising a member intermediate said springs actuatable by either piston upon a predetermined pressure being exerted thereon; and passage means connecting said valve means with said pistons for communicating operating pressure thereto.