WO1996001759A1

WO1996001759A1 - Hydraulic steering device

Info

Publication number: WO1996001759A1
Application number: PCT/DE1995/000925
Authority: WO
Inventors: Wolfgang Gabriel
Original assignee: Wolfgang Gabriel
Priority date: 1994-07-11
Filing date: 1995-07-10
Publication date: 1996-01-25
Also published as: DE19522057C1

Abstract

A hydraulic steering device for motor vehicles, in particular private cars, has a steering drive having a work cylinder with a working chamber and a working piston with a piston rod, as well as cylinder bottoms that delimit the working chamber and in which the piston rod is centrally guided. One cylinder bottom has a cap with a hub with a spindle nut linked to a steering wheel and in which a threaded spindle is rotatably mounted. The threaded spindle is linked in its axial prolongation to the piston rod and to an anti-twisting device. The other cylinder bottom has pressure connections linked to the working chamber through channels and to the steering cylinder through lines. The object of the invention is to develop a steering device of said type, so that its field of application is enlarged, its reliability and safety are increased and its maintenance costs are minimised. For that purpose, one work cylinder (1) has several mutually separated working chambers (I - IV) in which sliding working pistons (11, 12) are secured against rotation and co-operate in a manner known per se through a channel system and without auxiliary pressure with wheels capable of being steered by steering cylinders.

Description

description

Hydraulic steering device

Technical field

The invention relates to a hydraulic steering device for motor vehicles, in particular for passenger cars, with a steering drive with a working cylinder with a working chamber and a working piston with a piston rod, as well as cylinder bottoms closing the working chamber, in which the piston rod is guided centrally and a cylinder bottom with a cap has a hub with a spindle nut, which is connected to a steering handwheel and in which a threaded spindle is rotatably mounted, which is connected in its axial extension to the piston rod and an anti-rotation device, and finally the other cylinder base has pressure connections which pass through channels are connected to the working chamber and via lines to a steering cylinder.

State of the art

A generic steering device is known from GB-PS 451,224.

This steering device known according to the state of the art has the advantage that when the steering handwheel is actuated with rotation of the spindle nut connected to the steering spindle, it moves the piston rod with the working piston attached to it, which means that hydraulically supported steering without pressure support by corresponding pumps pen is possible.

However, this known solution has the disadvantage that both the threaded spindle and the piston rod are arranged unprotected outside the working cylinder. When the steering handwheel rotates, the threaded spindle also moves through the hub in the cap of one of the two cylinder bases assigned to the working cylinder, as a result of which additional space is required in this area, as well as covers and injuries are possible.

In addition, there is a disadvantage in the bulky and exposed anti-rotation device, as a result of which impairments can occur during the operation of the steering device. In addition, the sensitive parts such as the piston rod and threaded spindle, with their respective bearings or guides, require additional maintenance and sealing measures, so that this solution, which is known from the prior art, is susceptible to faults and can only be used in a narrowly limited area of application is.

Presentation of the invention

It is therefore an object of the invention to further develop the steering device of the type mentioned at the outset in such a way that the field of application is expanded, the reliability and safety are increased and the maintenance outlay is minimized.

To achieve this object, the invention proposes, starting from the steering device of the type mentioned, the characterizing features of the main claim. Advantageous embodiments of the invention are described in subclaims 2 to 15.

The solution according to the invention creates an overall compact and safe steering drive which is particularly suitable for smaller and light motor vehicles such as for example, cars. In addition, this steering drive is characterized by its maintenance-free nature and it can be flexibly coupled to the steering handwheel, which prevents injuries in this area.

The piston arrangement which is directly connected to the steering spindle causes the working medium to be pressed through the special upstream channels and the respective tie rod bore into the working chambers in the steering cylinder. As with the prior art, no auxiliary worker via pumps is required for this. In addition, compared with the prior art, there is the advantage that all the sensitive parts that belong directly to the working cylinder and that allow the movement and power transmission are arranged within the working cylinder. Furthermore, no supply devices for the production of auxiliary workers, such as pumps or similar devices, or assemblies for the control of valve arrangements that are usually required, are available.

A prerequisite for the function of such a steering device is that the working medium is under pressure, so to speak that it is “preloaded”. The rooms, hose and pipelines carrying the working medium must also be completely free of air.

Under these conditions, the working medium in the working chambers of the working and steering cylinders can be moved into any of the two degrees of freedom of the pistons when the ball screw is rotated and the barrel cylinder is thus displaced. As a result of the piston movement, the liquid column is displaced via the pressure connections and corresponding pressure lines into the steering cylinder, as a result of which the pistons are also moved. The steerable wheels connected to the pistons or their piston rods can thus be turned in any desired angle depending on the direction of rotation of the steering handwheel.

Depending on the application, the steering deflection of the wheels can be varied by means of ball screws of different lengths or stroke lengths of the pistons.

In addition to the solution described, the steering device according to the invention can also be reinforced with hydraulic or pneumatic auxiliary forces or with a vacuum, thereby expanding the field of application.

Instead of the ball screw drive of the barrel cylinder, other solutions are also suitable, for example a large threaded spindle drive. However, preference will be given to the ball screw drive because of the extremely smooth running.

The measures provided for in subclaim 2 are suitable for prestressing the working medium in any position of the working piston with a defined pressure. In addition, the air cushion present in the auxiliary piston bores in the area of the spring can be used as an auxiliary force, which thus serves to support the spring force.

In addition to the usual coil springs, cup springs or other suitable spring elements can also be used.

The auxiliary pistons for the pretensioning of the working medium can advantageously be used as signal generators, for example when the working pressure of the working medium drops. The feature in the lower saying 3 suitable.

The measures according to subclaim 4 serve to ensure the air exchange of the spaces of the steering drive which are not filled with working medium. The air in these rooms can thus be displaced without counter pressure building up to the working pressure of the working medium. It is also possible to arrange ventilation bores in the cylinder walls outside the working chambers.

The feature of subclaim 5 is provided so that the steering drive can be used at temperatures below the freezing point, for example.

The measure of subclaim 6 is suitable for maintaining the auxiliary pistons smoothly and at the same time providing a sealing surface with respect to the bore wall and the tie rod. Appropriate sealing and sliding rings on the contact surfaces between the piston and bore walls increase the effectiveness.

Finally, the measures according to subclaim 7 are intended to prevent the working pistons from rotating in the respective working chambers when the ball screw drive is actuated to initiate a steering movement.

The measures of subclaims 8 to 12 are particularly suitable for using the cylinder chambers still present as working chambers for driving additional secondary working or steering cylinders.

In addition, it is possible to use these working chambers formed in this way alternatively as additional working cylinders for securing purposes in the event that one of the first-mentioned working chambers or a pressure line in this regard is leaky or even fails. With appropriate switching of the pressure lines from the working chambers of the steering device to the secondary working cylinders, failures, accidents or the like can thus both be recognized in good time and largely avoided.

In order to avoid sluggishness or to prevent failures of the spindle drive by clamping or pressing the sliding and rotating parts within the working cylinder, the measures of subclaim 13 are particularly suitable.

Finally, the measures of subclaims 14 and 15 contribute to avoiding air pockets in the area of guiding and securing the rotating cylinder in the assembly and jam of the working medium when operating the steering device. Malfunctions are possible without these measures.

By means of sufficient clearance between the ball screw and its associated ball screw nut, on the other hand, additional pressure compensation measures are fundamentally not necessary in this area of the steering device.

embodiments

The structure and the mode of operation of the invention are explained in more detail using two exemplary embodiments and with reference to drawings. In the accompanying drawings:

1 shows an axial section through the steering drive according to the invention according to section AA in FIG. 2;

FIG. 2 shows a view in the direction H according to FIG. 1; 3 shows a radial section through the steering drive along the section course BB according to FIG. 1;

4 shows a radial section along the section line C - C according to FIG. 1;

FIG. 5 shows an axial partial section along the section course D - D according to FIG. 2;

Figure 6 is a schematic representation of a steering drive with a double-acting steering cylinder, lying transversely to the direction of travel.

7 shows a schematic illustration of a steering drive with a steering cylinder articulated on one side;

8 shows a longitudinal section of the steering drive with a sealing disk according to section A '- A' in FIGS. 9 and

9 shows the view in the direction H ^* according to FIG. 8.

Embodiment 1;

In FIG. 1, a working cylinder of a steering device according to the invention is designated by position 1. The working cylinder 1 has two cylinder chambers 2 and 3, which are separated from one another by an intermediate ring 4.

On its left side in the drawing, the working cylinder 1 is closed off with an intermediate ring 5, which is covered with an outer cylinder cover 6. On the axially opposite side of the working cylinder 1, the cylinder chamber 3 is sealed with a cylinder bottom 7. As can be seen in connection with the following FIGS. 2 to 4, the cross-sectional areas of all the individual elements of the working cylinder 1 are essentially quadratic, the cylinder bore with the cylinder walls 2.1 and 3.1 is usually circular.

The outer cross-sectional area makes it possible to arrange tie rod holes 8 to 8.3 over the entire length of the working cylinder 1 in the corner regions, in which tie rods 9 are provided. The tie rods 9 clamp the cylinder chambers 2 and 3 as well as the intermediate rings 4 and 5, the cylinder cover 6 and the cylinder base 7 against each other, whereby a stable unit is formed.

In the interior of the cylinder chambers 2 and 3 there is an axially displaceable cylinder 10, on the axial end of which working pistons 11 and 12 are fastened, for example shrunk on. The cylinder surfaces of the working pistons 11 and 12 are arranged in a known manner in a liquid-tight but displaceable manner with respect to the walls 2.1 and 3.1 of the cylinder chambers 2 and 3. Working chambers I and II are thus formed between the pistons 11 and 12 and the intermediate ring 4. The cylinder 10 is also sealingly guided on its outer surface with respect to a guide 4.1 provided in the intermediate ring 4.

The cylinder 10 is also axially partially guided on a guide 13 designed as an anti-rotation device, which is fastened in the cylinder base 7. On its outer surface, the guide 13 has a geometry that deviates from the cylinder shape and is, for example, hexagonal (FIG. 4). The individual surfaces of the guide 13 preferably run axially parallel. The cylinder 10 is substantially tubular with an inner surface adapted to the guide 13. This makes it possible to move the cylinder 10 with the pistons 11 and 12 in the working chambers I and II in a rotationally secure manner.

On the left side of the drawing, a ball screw nut 15 is inserted axially in the cylinder 10, whose balls 16 in conjunction with a corresponding ball screw spindle 17 allow the cylinder 10 with its working pistons 11 and 12 to move when the ball threaded spindle 17 is rotated.

The ball screw 17 is rotatable in a bearing 18 between the hissing ring 5 and the cylinder base 6 and is mounted so as to be non-displaceable in the axial direction and sealed against loss of liquid, for example with sealing rings 19, and connected in the further course to a conventional, but not shown, steering handwheel.

Auxiliary piston bores 20.1 and 20.2 are arranged in the tie rod bores 8.1 and 8.2 in the area of the cylinder chamber, in which auxiliary pistons 21.1 and 21.2 are each displaceably arranged against a spring 22.1 and 22.2 resting on the intermediate ring 5. The auxiliary pistons 21.1 and 21.2 are sealed with mechanical seals against the wall of the auxiliary piston bore 20.1 and 20.2 and against the tie rod 9, for which purpose the corresponding surfaces are ground.

The auxiliary piston bore 20.1 is connected to a pressure connection 23 via the tie rod bore 8.1 and via an overflow channel 24 introduced into the cylinder base 7. The pressure connection 23 is not described in more detail connected to the cylinder base 7. Furthermore, the tie rod bore 8.1 is connected to the working chamber II of the working cylinder 1 via an overflow channel 28.1 in the intermediate ring 4.

The auxiliary piston bore 20.2 is in accordance with the lower sectional view of FIG. 1 via the tie rod bore 8.2 with a pressure connection 25, not described in detail, via a further overflow channel 26. Compared to the preceding description of the upper sectional view of the drawing, however, there is a connection from the pressure connection 25 to the working chamber I. For this purpose, an overflow channel 28.2 is provided in the intermediate ring 4 within a bore 27 receiving the tie rod 9, which opens into the tie rod bore 8.2.

As can also be seen from FIG. 1, sealing rings 29 to 31 are provided between all the individual components, which prevent the working medium from leaking out of the working chambers I and II and that, in addition, the working cylinder 1 is sealed as a whole.

FIG. 5 shows the connection between the spaces of the cylinder chambers 2 and 3 lying on the outside according to the drawing, which serves to exchange air when the working pistons 11 and 12 move. For this purpose, overflow channels 33 and 34 are introduced in the intermediate ring 5 and in the cylinder bottom 7 such that they have an opening in the respective interior of the cylinder chambers 2 and 3 and the other opening in the passage for the tie rod 9 in the tie rod bore 8.3.

Finally, FIGS. 6 and 7 show steering drives which are shown very schematically and show two possible uses in connection with different types of steering cylinders. In FIGS. 6 and 7, the pressure connections 23 and 25 on the working cylinder 1 are arranged radially on the respective working chambers I and II for simpler illustration.

In FIG. 6, the pressure connections 23 and 25 are connected via partly rigid and partly flexible line connections to a steering cylinder 40 arranged transversely to an assumed direction of travel and its working piston 41.

The steering cylinder 40 is connected in a conditionally movable manner at a bearing point 42 to a rigid front axle 43, shown here, of a vehicle (not designated in any more detail). A double-acting piston rod 44 is articulated at its distal end, which is located outside the steering cylinder 40, to a steering lever 45, which is connected to a steering knuckle 46 each of the steerable wheels 47.

In FIG. 7, a steering cylinder 50 is arranged, for example, on a side of the vehicle in the direction of action of its working piston 51, which is longitudinal to the direction of travel, with a piston rod 52.

The piston rod 52 is connected to a steering lever 53 which is connected to a track lever 54. The track lever 54 is in turn connected via a tie rod 55 to a steering lever 56, which in turn is connected to a steering knuckle 57 of wheels 59 which are also articulated on a rigid axle 58. To steer the wheels 59 on both sides, the steering knuckle 57 of the left-hand wheel 59 in the drawing is connected to the track lever 54.

Example 2: According to FIGS. 8 and 9, in addition to the means described according to embodiment 1, a sealing washer 60 is arranged within the guide bore of the barrel 10 between the axially opposite ends of the guide 13 and the ball screw 17.

The sealing disk 60 thus forms a media-tight closure of the guide bore, as a result of which an additional working chamber III between the intermediate ring 5 and the piston 11 on one side and an additional working chamber IV between the cylinder base 7 and the piston 12 the other side of the working cylinder 1 are formed.

The sealing disk 60 can advantageously be designed like a conventional hydraulic piston. It is used essentially free-standing, but must be designed to be sealed and at the same time sliding on the wall of the barrel 10 so that the barrel 10 is sufficiently movable and the function is guaranteed.

In connection with the sealing disc 60, a radial bore 61 is arranged in the wall of the working chamber III near the intermediate ring 5, which is connected in a conventional manner to a further secondary working cylinder (not shown) via a pressure connection 62.

The bore 61 and the pressure connection 62 can also alternatively be connected in a correspondingly sealed manner to the working chamber III, for example in the intermediate ring 5 and through the cylinder base 6 (not shown).

In an equivalent manner, the working chamber IV has a bore 63 and a pressure connection 64, which are advantageously arranged on the cylinder base 7 and a di enable correct media supply and discharge in and out of the Work Chamber IV.

In order to be able to supply the working chambers III and IV with prestressed working medium, the two tie rod bores 8 and 8.3 are respectively provided with auxiliary piston bores 20.3 and 20.4 and with auxiliary pistons 21.3 and 21.4 with spring elements 22.3 and 22.4.

In order to generate a corresponding counter pressure to the working medium in the rest position, the auxiliary piston bore 20.3 assigned to the working chamber III is rotated by 180 ° with respect to the other bores.

Furthermore, bores 65 and 66 are provided, which produce a connection for the pressure medium between the auxiliary piston bores 20.3 and 20.4 via the tie rod bores 8 and 8.3 with the respective working chambers III or IV. These bores 65 and 66 are preferably made outside the stroke of the pistons 11 and 12 in the area of the intermediate ring 5 or the cylinder base 7 and in a bore axis inclined to the cylinder axis or radially in the respective cylinder wall.

Furthermore, an axial bore 67 can be provided, which begins on the end face of the guide 13 in the area of the sealing disk 60 and ends in a radial bore, which opens into the work chamber IV in the area of the cylinder base 7 and prevents the occurrence of congestion Moving the barrel 10 is useful.

Finally, it can be advantageous if the guide 13 is radially movable to a limited extent in order to avoid jamming during the movement of the barrel cylinder 10. For this purpose, an elastic connection 68 between the guide 13 and The cylinder base 7 is provided, which allows the guide 13 to move radially with a high degree of rotation. Alternatively, the spindle 17 or the ball screw nut 15 can be flexibly mounted.

If the working cylinder 1 is equipped with the described sealing disk 60, the measures for air balance between the working chambers III and IV are omitted. The respective bore 33 in the intermediate ring 5 and the bore 34 in the cylinder base 7 are not introduced.

With the help of the sealing disk 60, the area of application of the steering device can thus be expanded. In addition to its safe use as a steering drive for single steering systems, such a four-acting working cylinder can also advantageously be used for multiple steering systems. In addition, other applications in the field of hydraulics or pneumatics are possible.

The operation of the steering device according to the invention is explained with reference to embodiment 1:

If the ball screw 17 is rotated to the left, for example, the cylinder 10 is moved in the left-hand direction according to the drawing (see FIG. 1). As a result, a pre-stressed working medium located in the working chamber II can be displaced and can pass through the overflow channel 28.1 and through the tie rod bore 8.1 through the overflow channel 24 into the pressure connection 23.

From the pressure connection 23, the liquid column is fed, for example, to the steering cylinder 40 through appropriate pressure pipes and partially flexible pressure hoses. The working piston 41 is acted upon and initiates a corresponding steering movement of the wheels 47 via the piston rod 42, the steering lever 45 and the steering knuckle 46. At the same time, the liquid column located in the other working chamber of the steering cylinder 40 is shifted in the opposite direction via the other lines and the pressure connection 25, using the tensile forces generated.

The working medium is constantly biased in the respective auxiliary piston bores 20.1 and 20.2 by the auxiliary pistons 21.1 and 21.2 and the springs 22.1 and 22.2, whereby an immediate transmission of movement from the respective working piston 11 or 12 to the steerable wheels is possible. Steering ratios that differ from one another can be achieved by different pitches of the ball screw drive in the working cylinder 1 or differently effective piston surfaces of the working cylinders communicating with one another.

Likewise, a simple or tandem arrangement of working cylinders 1 or a multiple arrangement of steering cylinders, for example for more than two steerable wheels or axles, is possible.

Claims

Expectations

1. Hydraulic steering device for motor vehicles, in particular for passenger cars, with a steering drive with a working cylinder with working chamber and a working piston with piston rod, and cylinder floors that close the working chamber, in which the piston rod is guided centrally and with a cylinder bottom having a cap has a hub with a spindle nut, which is connected to a steering handwheel and in which a threaded spindle is rotatably mounted, which is also connected in its axial extension to the piston rod and an anti-rotation device, and finally the other cylinder base has pressure connections which are connected via channels the working chamber and are connected via lines to a steering cylinder, characterized in that

- The steering drive consists of at least one working cylinder (1) with cylinder chambers (2; 3) in which working chambers (I; II) are formed by an intermediate ring (4) in which working medium is biased with at least one steering cylinder (40; 50) in Connection is established

- The cylinder chambers (2; 3) of the working cylinder (1) via internal tie rods (9) with the cylinder bottom (6) with the intermediate ring (5) and the cylinder bottom (7) are axially connected, one in the working chambers (I; II) axially displaceable barrel cylinder (10) with working pistons (11; 12) attached to the end face is provided, - the barrel cylinder (10) on the one hand in an axial guide (4.1) arranged in the intermediate ring (4) and on the other hand by means of a Centric cylinder base (7) connected guide (13) is guided against rotation,

- The barrel cylinder (10) has in its end associated with the cylinder chamber (2) axially a ball screw nut (15) with a corresponding ball screw spindle (17) which by means of bearings (18) between the cylinder bottom (6) and the intermediate ring (5) is rotatably and media-tightly mounted and is further connected to a steering handwheel,

- The pressure connection (23) on the cylinder base (7) is connected to an overflow channel (24) which is connected via a first tie rod bore (8.1) and a first overflow channel (28.1) connected to the tie rod bore (8.1) in the intermediate ring (4) the Chamber of Labor (II) communicates and that

- The pressure connection (25) on the cylinder base (7) is connected to an overflow channel (26) which is connected to the second overflow channel (28.2) via a second tie rod bore (8.2) and one in the intermediate ring (4) with the second tie rod bore (8.2) Working chamber (I) is connected.

2. Hydraulic steering device according to claim 1, characterized in that the Zugankerbohrun¬ gene (8.1; 8.2) in the area of the working chamber (I) each have an auxiliary piston bore (20; 20.1) with an auxiliary piston (21) acted upon by a spring (22) ) have, which is guided on the respective tie rod (9).

3. Hydraulic steering device according to claim 2, characterized in that the auxiliary pistons (21) are designed as pressure sensors or are connected to pressure sensors.

4. Hydraulic steering device according to one of claims 1 to 3, characterized in that between the intermediate ring (5) and the working piston (11) Space formed in the cylinder chamber (2) with the space in the cylinder chamber (3) formed between the cylinder base (7) and the working piston (12) via the space in the cylinder base (7) and in the intermediate ring (5) and with a third tie rod hole (8.3) connected overflow channels (30; 34) is connected for air exchange.

5. Hydraulic steering device according to one of claims 1 to 4, characterized in that a highly viscous, temperature-resistant liquid, for example brake fluid, is used as the working medium.

6. Hydraulic steering device according to claims 2 to 5, characterized in that the tie rod (9) and the auxiliary piston bores (20; 20.1) are ground.

7. Hydraulic steering device according to An¬ claims 1 to 6, characterized in that the guide (13) is preferably designed axially multi-surface as anti-rotation and connected to the cylinder bottom (7) and that the cylinder (10) axially on the guide (13th ) slides.

8. Hydraulic steering device, in particular according to claim 1, characterized in that the guide bore of the barrel (10) between the axially opposite ends of the spindle (17) and the guide (13) is closed in a media-tight manner.

9. Hydraulic steering device according to claim 8, characterized in that the media density

Closure is designed as a sealing washer (60) and is preferably displaceable.

10. Hydraulic steering device according to claims 8 and 9, characterized in that working chambers (III; IV) are formed, the working chamber (III) via a channel (61) with a pressure connection (62) in the wall of the cylinder chamber (2) or in the cylinder cover (6) and the intermediate ring (5) and the working chamber (IV) are connected to further, secondary working cylinders via a channel (63) with a pressure connection (64) in the cylinder base (7).

11. Hydraulic steering device according to claim 10, characterized in that the working chamber (III) via a bore (65) and the working chamber (IV) via a bore (66) with pressurized auxiliary piston (21.3; 21.4) are connected , which are provided in auxiliary piston bores (20.3; 20.4) in the tie rod bores (8.3; 8) or outside the working cylinder (1).

12. Hydraulic steering device according to claim 11, characterized in that the auxiliary pistons (21.3; 21.4) are designed as pressure sensors or are connected to pressure sensors.

13. Hydraulic steering device according to one of claims 1 to 12, characterized in that the ball screw (17) and / or the ball screw nut (15) and / or the guide (13) are elastically mounted.

14. Hydraulic steering device according to one of claims 1 to 13, characterized in that the guide (13) has means for pressure compensation.

15. Hydraulic steering device according to claim 14, characterized in that the means for pressure compensation as an axially and radially extending bore (67) in the guide (13) or as a groove arrangement running axially in the wall of the guide (13) between the sealing disk (60) and the cylinder base (7).

- 6 sheets of drawings -