DE1655316B2 - Hydraulic power steering - Google Patents

Description

The invention relates to a hydraulic power steering for vehicles according to the preamble of Claim 1.

In known such hydraulic power steering systems for vehicles, the valve body must be in In the first stage of their movement the return bofmingen close before the actual pressure supply to the hydraulic motor can begin. The well-known hydraulic power steering therefore has system-related a certain, unavoidable and relatively large backlash in the steering. so In addition, the known vehicle power steering is disadvantageous in that it has two of each other separate electromagnets must work (US-PS 737X

The aim of the invention is thus to provide a hydraulic power steering system of the type mentioned at the beginning To create a species in which the steering lost motion is significantly reduced

To solve this problem, the measures of characterizing part of claim 1 provided. In this way, either the connection path is already there to reverse at the beginning of a steering movement from the outset, locked or it will be closed by a Slight movement of the armature, which can be triggered by the smallest torque in the closing position moved FOr the closing of the connection path to the return flow is no or only a minimal one Steering wheel movement required »In this way, steering backlash is reduced to a minimum

Advantageous further developments of the inventions are characterized by the subclaims

In the particularly advantageous embodiment according to claim 5, the connection path is to the return locked from the start, so that when the steering wheel is actuated, the actual valve body actuation occurs immediately can be done.

The advantageous further development according to claim ensures that · also with by the anchor closed valve body bore a suction of pressure medium from the container during steering operations is possible that can be done with minimal effort, d. H. do not require the assistance of an assistant.

The invention is exemplified below described with reference to the drawing; in this shows

Fig. 1 is a schematic view of a hydraulic power steering for motor vehicles and

F i g. 2 is a schematic view of a modified embodiment.

The steering device for a motor vehicle has a steering wheel 1, a steering gear 2, a pitman arm 3, a front axle 4 shown in dashed lines, a tie rod 5, wheels 6 and an electrical transmitter 7 on. The transmitter 7 can be on a steering column 8, on the pitman arm 3 or on another suitable one Place of the steering device to be attached. The encoder 7 can also be added to an already

3 4

existing steering to be attached. Annular space 22 in the respective end space 23 and from

The electrical transmitter 7 is in one branch of a there via the working line 29 or 30 in the

electrical bridge circuit 11 connected to the corresponding chamber of the hydraulic motor 9 to

a voltage source 12 is fed and Lerikunterstütwng comes from the hydraulic motor 9

Bridge current emits, the size and direction of which is displaced by 5 reverse flow oil flows over the respective other

the size and direction of the torque in the working line 29 and 30 through the bore of the not

Vehicle steering depends. To reinforce this valve body 20 or The bridge circuit 11 can receive an electrical current 21 through a return 39 to the storage container 18. Amplifier 13 be connected downstream. When changing the direction of the steering torque A double-acting io engages the jump bar 5 and the direction of movement of the changes accordingly

hydraulic hydraulic motor 9 by means of a piston rod armature 31 and thus the direction of actuation.

10, which can be designed as a steering shock absorber. In the embodiment according to FIG. 2 is the

can. Magnetic armature 43 designed in two parts. It consists of

To feed the hydraulic power steering is a two parts 34, 34a, which by one between them Pump 14 is provided, which are biased by the vehicle engine or 15 lying spring 35 so that

is driven by an electric motor. The pump the two end faces 36 and 37 of parts 34 and 34a

14 sucks pressure medium from a storage container 18 to rest on the end faces 24 of the valve body 20,

and loads can be brought via a loading valve 15 and a check valve 21. Through holes 38 in the parts

16 a memory 17. 34 and 34a ensure that the anchor 43

The memory 17 is via a pressure line 19 with 20 through which a pressure equalization takes place

a solenoid control valve 41 according to FIG. 1 or 42 according to Due to a steering torque caused

F i g. 2 in connection. called current flow in the spook 26 shifts In both embodiments, the magnet control armature 43 is one of the valve bodies 20, 21 against the

valve 41 and 42 provided with a longitudinal bore, axially in spring 28, so that there the pressure medium on the

the two coaxially located valve bodies 20 and 21 in the 25 annular space 22 into the end space 23 and then through the?

Distance from each other are slidably arranged. To the respective working line 29 or 30 in the corresponding

each end of the longitudinal bore of the valve 41,42 is a chamber dis the hydraulic motor 9 flows through

Front space 23 is provided, the return flow of the pressure medium in the other work line via a working line

29 or 30 with an associated working space of the device 29 or 30 via the space 23 and the bore 27

Hydraulic motor 9 is connected to 30 of the other valve body 20, 21 is the respective One end of the valve bodies 20, 21 protrudes into the body 34 or 34a of the armature 43 against the pressure

the end spaces 23 and are here with one of the spring 35 from the end face of the corresponding

conical extension provided. Lifted by a spring Vontilkörpers 20,21, so that the pressure medium

28, the valve bodies 20 and 21 are in their through the bores 38 and the armature 43 to the return

Closing pitches preloaded near the conical 3s 39 can flow off. Each valve body 20, 21 has an extension according to FIG. 1 and 2 is still one between the Annular space 22, which is connected to the pressure line 19 in hydraulic outward and return lines 29, 30 Connection is furthermore each valve body 20, switched bypass line 33,40 with switched on

21 provided with a through hole 27. th check valves 32 provided with the

According to FIG. 1, the return 39 is connected between the two valve bodies 40. This achieves that

20,21 an armature 31 axially movable at a distance from the even if in the embodiments according to

The end faces 24 of the valve bodies 20, 21 are arranged. 1 and 2 the steering torque reaches a value Armature 31 has a smaller diameter than in the case of the magnet armature 31, 43, the end face 24

the longitudinal bore of the valve and is just touched by springs 25, a valve body 20,21 and thus the

which each on a tapered projection of the valve body 45 closes bore 27, but the valve body still

20, 21 sit, is not moved between the valve body end faces 24, a steering movement is possible! ^; ch is there

held centrically. In the area of the tapered front then one of the two check valves 32 and the

The jump of the valve bodies 20, 21 is the axial bore of the lines 33, 40 from the container 18 liquid Valve can be sucked in via a return 39 with the storage tank, whereby the working cylinder

18 connected. 50 of the 9 displaced oil volumes above the others

One in the solenoid control valve 41 in the area of the valve body 21 or 20 through its bore 27 to Armature 31 arranged coil 26 is with the container 18 outflow chin.

electrical transmitter 7 via the amplifier 13 and also in the event of a fault in the electrical

Bridge circuit 11 connected. see or hydraulic part of the plant is through the When the steering column 8 is rotated, the coil 55 bypass line is consequently always a safe actuation of the

26 guaranteed according to the direction and size of the steering. This ensures that

Steering torque flowed through by electricity, causing oil foams and the resulting vacuum formation

the armature 31 displaced accordingly in the axial direction is avoided softness of the steering,

will. According to FIG. 1 causes this shift according to the reference to the embodiment according to FIG. 1 is still

referenced one or the other side by placing the armature 60, dad Her armature 31 also with his

on the respective end face 24 of one of the two lateral surfaces in sliding contact with the wall of the

Valve body 20,21 that the central bore 27 can be arranged in the longitudinal valve bore. In this

corresponding Ventükörper closed, while the case would be the magnetic core with a longitudinal hole

other is opened further. Rises to the electrical or a notch along the jacket surface

Excitation by a corresponding current to be in the 65. Coil 26 is sufficiently activated, so one of the valve bodies 20 by the in F i g. 2 g (showed embodiment with

or 21 against the action of the respective spring 28 divided magnet armature 43, its end faces 36 and

shifted so that the memory pressure from the 37 by the biased spring 35 in contact with the

End faces 24 of the valve bodies 20, 21 are standing, the slight path of the magnet core 31 will also be up to the abutment on the end face 24 of the valve body 20, 21 avoided. The biasing force of the spring 35 is like this to be interpreted as being less than the electromagnetic force.

The pressure medium outlet 39 can be in the area of a

each tapered projection of the valve bodies 20, 21 may be provided.

The electrohydraulic valve 41, 42 according to the invention with a seat seal has opposite known Slide valves in particular have the advantage that no loss of thickness occurs in the memory 17, as is the case with Gate valves is the case.

For this purpose 2 sheets of drawings

Claims (6)

Patent claims: 1. Hydraulic power steering for vehicles with a pressure part, a hydraulic motor connected to the steering and a control magnet operated by an electrical transmitter that responds ^{to the torque of the 1- "K ^ w ** 1, soft from a central position ra two} Direction is adjustable, depending on the direction of the steering wheel deflection, the pressure over two work divisions in one or the other working space of the hydraulic motor, which leads an armature and two Vemgkörper a the m the middle position of the control valve, the connection between DruckmitteE-qaeäe aod hydraulic motor , whereby between the befdeH connections of the work divisions of the hydraulic motor ent direct Vg connected to a return is present, m characterized in that the anchor ßl. 34) of the solenoid control valve (4t, 42) from a central position to both sides relative to dect two valve bodies (20, 21) up to the facility ast one of these v is slidable and thereby closes its direct connection to the return 2. Power steering according to claim 1, characterized in that characterized in that the two valve bodies (20,21] | and the armature (31, 43) is arranged displaceably in a common bore of a valve housing are, the valve bodies (20, 21] i each one to the return and one to the: Druckmittefquene (14, 15, 16, 17) connected Annular space ($ 22 exhibit from those of the latter! is separated by a seat seal from an end space (23), which in turn is the consumer connections contains for the work guide supports of the hydraulic motor and each valve body (20, 21) an axial Has Dorchgangsbohnmg (27), each of which The end facing the anchor is displaceable by this. 3. Power steering according to one of the claims .or 2, characterized in that the armature (31) is constructed in one piece and is each provided with a spring (25) on both sides between the end faces (24) of the valve body (20, 21) facing the Dun Distance is kept centric 4. Servot sound according to claim 3, characterized characterized in that a connection to the return (39) is provided only on one side of the armature (31} is and there is a distance between its outer surface and the inner surface of the Ventflbohrung is that allows a flow of pressure medium 5. Power steering according to claim 1 or 2, characterized in that the armature (43) consists of two parts (34,34aJ, between which a compression spring (35) is arranged so that the end faces (36, 37) of its parts (34, 34a) rest on the end faces (24) of the valve bodies (0, 2 $) , and that a pressure compensation bore (38) is provided in each of the parts (34, 34a) 6. Power steering according to one of the preceding claims, characterized in that the working lines (29, 30) are connected to the return (39) via check valves (32).