DK149555B - HYDRAULIC STEERING DEVICE FOR A SERVOMOTOR ISAIR FOR DRIVER CONTROL - Google Patents

Description

149556

The invention relates to a hydraulic control device for a servomotor, in particular for controlling vehicles, according to the concept of claim 1,

In a known control device of this kind (DE-AS 23 05 798) 5, a quantity of pressure fluid is predetermined in the control circuit by means of the quantity adjustment device. The pressure conditions in the control circuit are transmitted to the working circuit by means of the pressure control device so that a flow rate proportional to the control circuit flows therein. This control device works excellently when the amount dispensed by the quantity adjustment device, as is usually the case, from a certain value slowly returns to zero. On the other hand, when the quantity adjusting device is activated very suddenly, a disturbing aftermath of the servomotor occurs.

There is further known a control valve for the servo motor of a vehicle control (US-PS 3 587 646), which has two cooperating, rotatable sleeve housings, adjustable against the force of a spring torsion bar, one of which is connected to a steering hand wheel and the other with the control device actuated by the servomotor. This establishes the connections between the pump connection and the one working connection leading to the servomotor, and between the other working connection and the tank connection over blind holes in the inner swivel sleeve 25. As a result, not only the pump connection is connected to the tank connection by an "open-center" structure in the neutral position, but also the working connections are connected to the tank connection. The control device can therefore be adjusted by external forces.

Further, there is known a switching valve for a piston device (US-PS 2 916 049), which can take several predetermined positions by means of a raster. In the neutral position the working connections leading to a servo motor are separated from the tank connection. In the "raise" and "lower" positions, respectively, one side of the servomotor is connected to the pump and the other side to the tank. In a free position, both working connections are connected to the tank connection so that the servomotor can move freely under the influence of external forces.

The object of the invention is to further design a control device of the kind specified in the introduction, in that it is better than hitherto prevented that the servomotor is adjusted in a disruptive manner when the quantity adjusting device is in its neutral position.

This task is solved according to the invention by the characterizing part of claim 1.

The invention is based on the recognition that the slider of the power comparator 15 slides by slowly decreasing the amount of control circuitry predetermined by the quantity adjustment device gradually returns to its neutral center position. On the other hand, when the amount of control circuit is suddenly interrupted, the power comparator slides are positioned relatively far from the neutral center position and need some time to return to the center position. During this time, the servomotor is added to another workload. If, according to the invention, the control connections of the quantity setting device in the neutral position are connected to the tank connection, then there is a correspondingly low pressure on these 25 Control connections. Similarly, the pressure in the power comparator's connected pressure chamber is rapidly decomposed and the slider quickly returns to the neutral center position. This prevents the running of the servo motor.

Due to the pressure reduction, favorable feedback conditions for the pressure control device appear so that according to claim 2 in the connection between the pressure chamber of the power comparator 3 and the associated control connection a throttle and a spring-loaded check valve can be laid. This allows a very simple wiring to optionally set each pressure chamber under the pressure of the associated control connection 5 or the pressure of the associated working connection.

With the precautions in claim 3, in the neutral position, the pressure in the pressure chamber of a reset element connected to the main valve can also be lowered to the tank pressure. Therefore, it is not possible that due to some external influence, such as an external force acting on the servomotor, pressure peaks occur which displace the reset element and, if so, briefly open the associated main valve.

For the construction of the quantity adjustment device, the characteristic of claim 4 is recommended for a quantity adjustment device known per se from DE-PS 12 93 029.

In the design of the quantity adjustment device of claim 5, the reflux control openings can have a very small cross-section, as the pressure fluid flowing over the quantity adjustment device flows back to the tank over the main valve held open by the resetting element, thus during circumvention of the quantity adjustment device. Also, in order to break down the pressure in the control lines, a very small connection cross-section is necessary, so that as a rule 25 can be satisfied with one bore cross section enlarging groove per circumferential row.

The invention is described in more detail below with reference to an exemplary embodiment shown in the drawing which is shown in FIG. 1 shows a wiring diagram for a hydraulic control device according to the invention in its neutral position, FIG. 2 shows the unwinding of the outer circumference of an inner swivel slide of a quantity adjustment device; FIG. 3 shows the unwinding of the inner circumference of an outer swivel slide of the quantity adjustment device of FIG. 2 and FIG. 4 is a partial section through housing and a two sliders of the quantity adjustment device along the line A-A in FIG.

2 and 3.

A servo motor 1 is provided with two sides 3 and 4 located on both sides of the piston 2 which have connecting lines 5 and 6.

There is a control circuit 7 having a quantity adjustment device 8 having a connection 9 for a control circuit pump 10, a tank connection 11 for the connection with a tank 12 15 and two control connections 13 and 14. The quantity adjustment device is actuated by means of a control handwheel as actuating link. 15, such that a quantity of pressure fluid corresponding to the steering hand wheel flows from the pump connection 9 to the control connection 13 or 14. In the neutral position shown, the pump connection 9 and the tank connection 11 are connected to one another over a short circuit path 16. At the same time, in this neutral position, the control connections 13 and 14 over channels 17 connected to the tank connection 11. The control circuit has two connecting lines, the control line 18 25 for the left and the control line 19 for the right. These lead to a left control valve 20 and a right control valve 21. The left control valve 20 has a plunger 201. The first connection 202 communicates with a ring groove 203 in the piston 201, the second connection 204 with a ring groove 205 in the housing. Triangle-shaped grooves 206 are provided in the plunger with which a connection can be made between the ring grooves 203 and 205. The plunger is loaded in the closing direction by a spring 14 and the pressure in a first pressure chamber 208 and in the opening direction of the pressure in a second pressure chamber 209. Since both pressure chambers are connected to the terminals 202 and 204, the opening cross-section and the pressure drop in this valve are in a fixed relationship with each other. The control valve 21 has a similar structure, the corresponding parts being provided with the reference numerals 211 - 219. The second valve connection 204 is connected to the connection 5, the valve connection 214 to the connection 6 of the servomotor 1.

The work circuit 22 has two main valves 23 and 24 which are of a similar construction to the control valves 20 and 21 and whose individual parts are therefore provided with reference numerals 231 - 239 and 241 - 249. While the other valve connections 234 and 244 are connected to the servomotor connections 5 and 15 6, the first valve connections 232 and 242 face connecting lines 25 and 26 in connection with the working connections 27 and 28 of a pressure control device 29 which has a connection 30 for a working circuit pump 31 and two connections 32 and 33 for the connection to the tank 12 .

The pressure control device 29 has a valve slider 34 with two ring grooves 35 and 36. The slider cooperates with three ring grooves 37, 38 and 39 in the housing. On the end faces are pressure chambers 40 and 41. The pressure chamber 40 is connected via a throttle 42 to the control line 18 acting as a connecting line and 25 via a check valve 43 to the ring note 36. The pressure chamber 41 is connected via a choke 44 to the control line 19 acting as a connecting line. As a result, the pressure regulating device 29 acts as a force comparator in which the slider 34, in dependence on the higher pressure, in the control lines 18 and 19 acting as connecting lines, is displaced, thereby causing a throttle to the ring grooves 35 or 36 are raised and passed over the check valve 43 or 45 into the opposite pressure chamber. In this way, the pressure on the working connections 27 and 28 is equal to the pressure in the control lines 18 or 19 acting as a connecting line.

Each work valve 23, 24 is connected to a reset element 46 or 47. The reset element 46 has a piston 461 which is, on the one hand, under pressure in the second pressure chamber 239 and on the other side under the pressure of a third pressure chamber 462. This is over a throttle 463 connected to the control line 7 of the control circuit 7, which acts as a connecting line 19 by means of an extension 10 464, the piston 461 can open a switching valve 465 which lies in a line 466 extending between the terminals 232 and 234 and having a first throttle 467 in front of the first pressure chamber 238 and a second throttle 468 in the rear. A similar structure is found at the right reset element 47.

The connections 5 and 6 are connected in a conventional manner to the tank 12 over suction valves 48 and 49 as well as over pressure valves 50 and 51.

In this control device, the following operation emerges: In the neutral position 20 of the quantity adjustment device 8, the pressure fluid reaches from the control circuit pump 10 over the short-circuit path 16 immediately to the tank 12. Due to the ducts 17, the control lines 18 and 19 also act as pressure lines. As a result, the pressure regulating device 29 also occupies its neutral position, immediately 25 after the quantity adjusting device has reached the neutral position, because pressure means can quickly run from the pressure chamber 40 or 41 to the tank. Therefore, the pressure fluid of the working circuit 31 also flows directly back to the tank 12. All control and main valves 20, 21, 23 and 24 are closed. Pressure peaks occurring due to external forces on one side of the servo motor 1 cannot open the valves; nor can the reset elements 46, 47 be actuated, since these pressure peaks cannot be reflected in the control lines 18 and 19. acting as connecting lines, as a result, the piston 2 remains in the predetermined position.

By turning the control handwheel as actuating link 15 to 5 on the right, pressure fluid reaches over the control line 18 acting as a connecting line to the control valve 20, whereby it enters an opening position corresponding to the amount. The pressure in the control line 18 acting as a connection line is generated by the pressure regulating device 29 also in the connection line 25. Since the valve connections 204 and 234 are connected to each other, the same pressure drop as at the control valve 20. As a result, the main valve opens. such that a quantity of pressurized fluid flows through which is proportional to the amount of pressurized fluid flowing through the quantity adjustment device 8. At the same time, the piston 471 of the reset element 47 is pressed to the right as the high pressure in the actuating conduit 18 acts as a connection line, thereby opening the switching valve 475, and pressure means flows over the throttle 20 477, the first pressure space 248, the arid throttle. 478 and the check valve 475 from the valve connection 244 to the valve connection 242. This results in a reduction of the pressure in the first pressure chamber 248 that the force exerted by the piston 471 on the piston 241 is sufficient to bring this towards the right to the opening position. In this way, the side 4 of the servomotor 1 is brought over the main valve 24 and the pressure control device 29 in connection with the tank 12.

If there are now external forces trying to push the piston 2 to the left, ie. in the opposite direction, so that a pressure shock occurs on the side 3. This pressure shock is reflected in the first pressure chambers 208 and 238, whereby the control valve 20 and the main valve 23 close somewhat. As a result, the thrust in the control lines 18 and 25 acting as connecting lines no longer gives rise to impact and, in particular, does not cause shock or impact on the steering wheel as actuating link 15.

On the other hand, if external forces attack the servomotor which tries to move the piston in the direction of the control movement, there is a risk that the piston will shift faster than the steering wheel wheel movement. However, such a faster movement causes the pressure on the side 3 to decrease.

This pressure drop also leads to a pressure drop in the control line 18 acting as a connection line, and thus in the third pressure space 472 of the reset element 47. As a result, the piston 241 of the main valve 24 moves to the left, resulting in a stronger throttle. This leads to a slowing of the piston movement because the liquid can no longer flow so quickly from the side 4. Due to the relatively small diameter of the piston 471 15 relative to the piston 241 of the main valve 24, pressure changes in the control line 18 acting as a connection line lead to relatively small force changes. which against the valve spring 247 also causes only small displacements of the piston 241, which is necessary to prevent overshoot. Despite the small diameter of the piston 471, the main valve 24 is usually opened as the pressure in the first pressure chamber 248 due to the throttles 477 and 478 is reduced by reflux operation.

By turning the steering wheel to the left, 25 pressure fluid from the quantity adjustment device 8 is passed over the control line 19 acting as a connecting line 19. In the mirror image the same conditions appear as in the previously described equipment.

If the quantity adjustment device 8 is suddenly set to zero flow rate 30, the pressure control device 29 can immediately follow, because the connection of the pressure chambers 40, 41 over the ducts 17 with the tank provides for a rapid emptying of the higher pressure chamber.

149555 9

The channels 17 of the quantity adjusting device can be constructed in a variety of ways. In a quantity adjustment device with two concentric slides arranged in a housing bore, as is known, for example, from DE-PS 5 12 93 029, it is sufficient to make a milling in the inner swivel slider. This is explained in connection with FIG. 2-4.

Of the quantity adjustment device 60 only the part having a valve housing 61, an outer pivot slider 62 and an inner pivot slider 63 are shown. In the housing are four ring grooves, of which the ring groove 64 is connected to the pump connection, the ring groove 65 with the tank connection, the ring groove 66 with one steering connection and ring groove 67 with the other steering connection. The outer pivot slider 62 has axially behind each other several circumferential rows of bores, namely short-circuit openings 68, connection openings 69, distributor openings 70, a first circumferential breakthrough 71, a second circumferential breakthrough 72, bores 73 for receiving a coupling shaft not shown. pins and connecting openings 74, 20 between which on opposite sides are two sections 75 for accommodating both sliders in their neutral position forcing, not shown, leaf springs. The inner pivoting slider has axially trailing successive functional elements which cooperate with the apertures just described: Axial short-circuiting notes 76, a circumferential groove 77 with axial groove extensions 78, between these arranged and interconnected axial grooves 79, which continue as first guide openings. 80, between these other guide openings 81 and 82 are arranged in two circumferential rows, breakthrough 83 for penetration of the driver pin, and sectioning 84 for penetration of the leaf springs produced by milling. In each circumference, a second guide aperture 81 and 82 is provided with grooves 85 and 86, which transversely cross the bore cross-section so much as to contact the breakthroughs 71a and 72a in the neutral position. In the housing 61, valve openings 87 are provided, which are connected via axial bores 88 to the displacement chambers of the measuring motor not shown.

In the neutral position, pressure fluid reaches from the pump connection over the ring groove 64, short-circuit openings 68, short-circuited grooves 76 and the inner space 89 of pivot slider 63, cut-outs 75 and connection openings 74 and ring groove 65 to the tank.

At the same time, one control connection over the ring groove 86, the breakthroughs 71a, the groove 85, the associated second guide opening 81 and the other control connection over the ring groove 67, the piercing 72a, the groove 86 and the associated second control opening 82 are connected to the inner space 89 and thus with the thought.

By rotating the inner pivoting slider 63 relative to the outer pivoting slider 62 to the right in the drawing, the short-circuit openings 68 are brought out of engagement with the short-end grooves 76 and the breakthroughs 72a out of engagement with the groove 86. Instead, the breakthrough 72 comes into contact. with the first control openings 80, while the breakthroughs 71 contact the second control openings 81. Thereafter, pressurized fluid flows from the pump connection over the ring groove 64, 20 the connecting opening 69, the circumferential groove 72, the axial grooves 78, part of the distributor openings 70 and the valve openings 87 to the displacement chamber of the measuring motor. From other displacement chambers, the pressure fluid reaches over other valve openings 87, second distributor openings 70, first control openings 80, breakthroughs 72 and 25 ring groove 67 for one control connection. The exiting, measured pressure fluid controls the working circuit and thus the servomotor. In a counterclockwise direction, the control connection connected to the ring note 66 is provided with metered pressure fluid.

Claims (4)

149555 1. Hydraulic control device for a servomotor (1), in particular for vehicle control, with a control circuit (7) having a quantity adjustment device (8) with a pump connection (9), a tank connection (11) and two control connections ( 13, 14), and two control valves (20, 21), each coupled between a control connection and one side of the servomotor (1), and with a working circuit (22) having a pressure control device (29) with a pump connection (30). ), a tank connection (32, 33) and two working connections (27, 28) for the return and return in the form of a force comparator holding the pressure at a working connection equal to the pressure at a control connection, and two main valves (23, 24), each of which is coupled between a working connection and a side of the servomotor, whereby the control (20, 21) and the main valves (23, 24. have one of the pressure drop occurring on them, and the force comparator has two pressure chambers (40, 41), each of which is perpetually associated with one of the st the yarn connections (13, 14), know the sign 20 in that the control lines (18, 19) and all of the connected pressure chambers (40, 41, 209, 219, 462, 472) in the neutral position of the quantity setting device (8) become pressureless by channel (17) in the quantity adjustment device (8), then the control connections (13, 25 14) connect to the tank connection (11). 2. A control device in which the pressure comparator (40, 41) of the power comparator is connected not only to a control connection (13, 14) but also to a check valve (43, 45) opening towards the pressure chamber with a working connection (27, 28). , according to claim 1, characterized in that a throttle (42, 44) and a non-return valve (43, 45) are arranged in the connection between the pressure chamber (40, 41) of the force comparator (14,455) and the associated control means (13, 14). ) is spring loaded. Control device, in which each main valve (23, 24) is connected to a reset element (46, 47) 5 with a pressure chamber, which forcibly opens the main valve under the influence of a pressure in a control line branch connected to the servo motor (1), according to Claim 1 or 2, characterized in that the reset element (46, 47) activating pressure chamber pressure also falls in the neutral position of the quantity adjustment device (8) because it is taken out in the control line (18, 19. between the control connection (13) of the quantity adjustment device (8). 14) and the control valve (20, 21). Control device according to one of claims 1-3, characterized in that - using a quantity adjustment device known per se, in which in a housing (61) containing the pump connection, the tank connection and the two control connections , there is provided an outer (62) and an inner (63) swivel slider which, in dependence on the rotation of an actuator (15) and the after-movement movement of a quantity measuring motor, can be turned towards each other and form a control valve at which the outer swivel slider has two perimeter rows arranged breakthroughs (71, 72) of which one perimeter row communicates with one control connection, and the other perimeter row communicates with the other control connection, and the inner swivel slider is associated, alternating with the measuring motor in connection first ( 80) and with other tank openings (81, 82) connected to the tank connection - the channel (17) is formed by the fact that for each circumference row at least one of the other control openings ( 81, 85; 82, 86) has a circumferential extent such that it is in the neutral position associated with a breakthrough (71a, 72a).