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
  • B62D5/09—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 means for actuating valves

Definitions

• Valve arrangement for a hydraulic control apparatus is a hydraulic control apparatus.
• the invention relates to a valve arrangement for a hydraulic control apparatus, in particular a hydrostatic steering device, having a load pressure-controlled priority valve according to the preamble of claim 1.
• a valve arrangement of that kind is known from DE 38 14 508 C2.
• a load pressure sensing line is provided which leads from the first outlet having priority to a load pressure sensing point in the control apparatus; the load pressure sensing point is arranged in the control apparatus behind the first throttle thereof.
• a pressure divider is formed by means of two throttles. The second pressure chamber is connected between the two throttles to the load pressure sensing line.
• the priority valve ensures that the pressure drop at the main throttle of the control apparatus is constant.
• the invention is based on the problem of providing a valve arrangement of the kind described at the beginning, in which the priority valve can be operated with a higher stand-by pressure.
• the pressure control valve can be arranged at any point of the load pressure sensing line downstream of the first throttle. Its arrangement on or in the housing of the control apparatus according to claim 2 is especially advantageous. This not only enables the pressure control valve to be housed with a saving of space; in addition there is a relatively high pressure in the connecting line between priority valve and control apparatus. The air entrained with the liquid under pressure flowing through the line is consequently correspondingly powerfully compressed. A "stiffer" system having an improved response time is produced.
• the pressure control valve is arranged on or in the housing of the priority valve, according to claim 3. This alternative arrangement can also be effected with a saving of space. In particular, no change to the control apparatus is required.
• the stand-by pressure can be adjusted in a simple manner by virtue of the adjustable valve springs according to claim 7.
• valve parts together in a common bore according to claim 8 facilitates assembly.
• the throttle openings according to claim 9 damp the movements of the valve piston.
• the through-openings according to claim 10 provide for an unobstructed flow of the liquid under pressure through the load pressure sensing line.
• the bridging section of conduit according to claim 11 is advisable. It provides a means of exerting an additional influenced on the valve function.
• Fig. 1 is a block circuit diagram of a valve arrangement according to the invention.
• Fig. 2 is a partial section through a slightly modified embodiment of the pressure control valve and the adjoining part of the priority valve housing.
• a priority valve 1 has an inlet P which serves for connection of a pump or similar pressure source, a first outlet CF, which serves for the connection of a pressure-side inlet 2 of a control apparatus 3, in particular a hydrostatic steering device, and a second outlet EF, which serves for the connection of a load, not illustrated.
• the first outlet CF has priority over the second outlet EF.
• the priority valve 1 has a load pressure connection LS which is connected by way of a hose line 4 to an inlet 5 which leads to a load pressure sensing point inside the control apparatus 3.
• the control apparatus 3 is furthermore connected by way of two work lines 6 and 7 to an apparatus 8 to be controlled, for example, a steering motor, and by way of a line 9 to a tank 10.
• the control apparatus 3 can be constructed, for example, as described in DE 38 14 508 C2.
• the priority valve 1 has a slide 11 which is loaded at one end by the pressure in a first pressure chamber 12 and at the other end by a pressure in a second pressure chamber 13 and the force of a spring 14.
• the first pressure chamber 12 is connected by way of a first throttle 15 to the first outlet CF.
• the second pressure chamber 13 is connected by way of a second throttle 16 likewise to the first outlet CF.
• the second pressure chamber 13 is further connected by way of a third throttle 17 and a pressure control valve 18 to the load pressure connection LS. In this manner a load pressure sensing line 19 is provided between the first outlet CF and the load pressure sensing point.
• the pressure control valve 18 has a slide 20 which is loaded at one end face 21 by the input pressure and at the other end face 22 by the output pressure and by a valve spring 23. The pressure drop at this pressure control valve is therefore kept at a value corresponding to the spring force.
• a spur line 24 having a throttle 25 bridges the pressure control valve 18.
• the slide 11 of the priority valve 1 operates in the customary manner for a dynamic load pressure system.
• a stream of oil flows continuously from the outlet CF by way of the throttles 16 and 17 to the inlet 5 of the control apparatus 3 and continues to the load pressure sensing point, not illustrated, inside the apparatus.
• the pressure control valve 18 is arranged additionally in this flow path. In this manner the entire pressure level is raised by the pressure drop of the pressure control valve.
• the pressure control valve 18 is illustrated inside the priority valve 1
• the pressure control valve 118 in Fig. 2 is arranged on the outside of the priority valve 101.
• the housing 126 of the priority valve of known construction has at one end of the second pressure chamber 113 a load pressure connection 127. Into this is screwed not the hose line, but the connector 128 of the tubular housing 129 of the pressure control valve 118. At its free end, the housing has a connection 127' which corresponds to the connection 127 and is now used for connection of the hose line 4.
• the pressure control valve 118 has a valve piston 120 which co-operates with a bushing 130 and carries a guide flange 132 provided with at least one throttle 131.
• a control groove 133 is connected by way of radial bores 134 to an inlet channel 139 which has the throttle 117.
• On displacement of the valve piston 120 the annular groove emerges to a greater or lesser extent from the bushing 130.
• a comparator piston 136 provided with through-openings 135 is biassed by the valve spring 123 against the valve piston 120.
• the valve spring 123 is supported by a screw-in spring supporting element 137. Its through-opening 138 is of hexagonal cross-section and can therefore be used for screwing in.
• the pressure control valve can also be arranged in the control apparatus 3, at the connection 5 or in the hose line 4.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Control Of Fluid Pressure (AREA)
• Safety Valves (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=7774188

Family Applications (1)

Country Status (3)

Families Citing this family (1)

Citations (3)

Family Cites Families (2)

• 1995
  • 1995-10-06 DE DE1995137241 patent/DE19537241C1/de not_active Expired - Fee Related
• 1996
  • 1996-10-03 AU AU71263/96A patent/AU7126396A/en not_active Abandoned
  • 1996-10-03 WO PCT/DK1996/000420 patent/WO1997013691A1/en active Application Filing

Patent Citations (3)

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