DE2945703A1 - Automatic double stroke control - has throttle valve blocking piston for control piston, and power transfer spring - Google Patents

Abstract

The control is for double acting piston/cylinder units, esp. plough turning appliances, to generate a double stroke dependent upon a pressure rise in a feed pipe. It has a control piston to connect working chambers of the unit to the feed- resp. a return pipe. A throttle valve (25) in the outlet pipe (24) of the working chamber (5) causing the second stroke phase, generates a pressure head. The pressure head charges a blocking piston (26), which stops the control piston (8) in an end position. Without a pressure head, the working chamber (27) of the blocking piston is connected via a throttle (28) to the outlet pipe downstream of the throttle valve. A spring (15) acts as power transmission between piston (3) and control rod (17), resp. rod and control piston. A weaker return spring (19) charges the control piston in the opposite direction. A control surface on the control piston may be charged hydraulically against the return spring, and has a control conduit (35). The control conduit is separated from the feed inlet (21) during the first stroke phase, and connected to it during the second phase.

Description

The invention relates to a control device with

the features of the preamble of claim 1.

Such a control device is already described in DE-OS 27 16 262 known. A spring-loaded locking device is used in a groove in the control piston engaging locking ball. The disadvantage of this arrangement is that an automatic Resetting of the control piston in the starting position after completion of the second Lifting phase and pressure drop in the supply line is not possible. The provision Rather, it must be carried out by a separate, manual switching process on an external one Valve, generally a valve on a tractor, can be made hydraulically.

This valve must be a four-way valve, since it has two lines Pressure must be applied. A control via a three-way valve like it sometimes only available is not possible. There is another disadvantage in that it is difficult to determine the length of the shift rod and the reversal point of the Coordinate control piston with the dead center of the piston. The change of direction takes place e.g. before the dead center, the liquid in front of the piston must in undesired The seals are compressed in a manner that can create considerable pressures and mechanical components and therefore a corresponding dimensioning is necessary do. Furthermore, it is not always guaranteed that under such conditions the kinetic energy of a plow or other device is sufficient, the dead position to overcome. This latter disadvantage is due to the installation of a pressure relief valve (DE-OS 27 39 736) tried to remedy this. However, the former disadvantages are with it has not been eliminated.

It has also been proposed (DE-OS 28 00 263), the location to make the control rod adjustable, including an externally accessible adjustment mechanism provided within the hollow bored control piston. But there is one here too automatic return to the starting position not possible. Also are at Changes in play or wear and tear, re-adjustment work required.

Finally, it is already known (DE-OS 2757467) that the second The working space causing the lifting phase shortly before and shortly after the dead center has been passed to depressurize by means of appropriate mechanical control of check valves. Here, too, the control piston must be reset by means of a pressure pulse. There is also the possibility of a hydraulic short circuit if the working area after the dead center is still connected to the process and the external kinetic energy is not large enough to move the piston past dead center by the necessary amount to move. Finally, it is not possible to compensate for changes in the dead center position.

It is therefore the object of the invention to provide a control device of the in Design in question so that a control via an external three-way valve can be initiated, provided that a second leading to the tank Connection is available or an intermediate storage of the pressure medium take place can. The reversal process should be automatic after switching the external valve expire. After switching back the external valve sometime after the Double stroke, the control piston should automatically reset to the starting position will. Finally, it should be ensured that the reversal in any case does not take place before reaching the dead center, so that pressure increases etc. are avoided and additional pressure relief valves are not required.

A reversal should in any case also without external kinetic energy to be possible.

The design should be cheap, simple and functionally reliable and within the scope of the usual installation dimensions, e.g. to be accommodated in a piston head or on one of these can be flanged to.

This object is achieved according to the invention with the features of the characterizing part of claim 1.

The advantage of this solution can be seen in the fact that manual intervention is only necessary before or after the double stroke and focus on simple switching an external valve. Additional switching movement to generate pressure pulses, It is not necessary to reset the control piston or the like. It is ensured, that switching to the second lifting phase only takes place after reaching dead center, even if there are relatively rough tolerances. Compressions more involved Volumes cannot therefore arise in the first place.

The subclaims relate to suitable individual training Components.

Claims 2 and 3 are based on positive or non-positive locking Blockages.

Claims 4 and 5 are based on the non-positive locking with a locking piston arranged transversely to the control piston.

Claims 6 and 7 relate to one in the form of an annular piston executed locking piston acting on Xlemmstück.

Claim 8 is directed to a bias of the spring.

Claims 9 and 10 describe two possible arrangements of the Feather.

Claim 11 has a relief device for content, which in particular a faster stroke when the piston is moved above dead center by external forces of the locking piston guaranteed.

On the basis of an exemplary embodiment shown schematically in the figures the invention is explained in more detail.

Figure 1 shows a control device with positive locking during the first lifting phase.

Figure 2 shows the same control device during the second lifting phase.

Figure 3 shows a variant during the first lifting phase with a frictional locking, relief device and spring in the piston.

Figure 4 shows a further variant during the first lifting phase an annular piston and clamping pieces for frictional locking.

A piston-cylinder unit has a cylinder 1 in which a piston 3 connected to an outwardly guided piston rod 2 is slidable is arranged. The piston 3 divides a piston rod within the cylinder 1 2 surrounding first work space 4 of a second work space 5, which is from a Cylinder head 6 is closed at the front. In the cylinder head 6 there is one Bore 7 running parallel to the axis of the cylinder 1, which is spaced apart arranged annular grooves T1, B, P, A and T2 expanded, the annular groove T1 being the working space 5 is closest. A control piston 8, which has three shoulders, slides in the bore 7 9, 10 and 11 connected by waists 12 and 13. the Shoulder 9 has an inner bore 14 which serves to receive a spring 15, which acts on a spring plate 16, which in turn is fixed to a shift rod 17 is connected. The shift rod 17 penetrates a sealed Coaxial with the bore 7 extending bore 18 and protrudes with its free end in the Workspace 5 into it. The spring plate 16 is against draining out of the bore 14 secured. On the shoulder 11 acts a return spring 19, which is on a Drilled shoulder 20 is supported. In the annular groove P opens an inlet connection 21, which through external control optionally connectable with a pressure medium source or a drain is.

The annular grooves T1 and T2 are via channels 22 and 23 with a drain line 24 connected, in which a resistance valve 25 is built. One as a stepped piston trained locking piston 26 has a working space 27, which with the channel 23 and therefore also connected to the drain line upstream of the resistance valve 25 is. The working chamber 27 is still connected to the downstream via a throttle point 28 from the resistance valve 25 lying part of the drain line 24 connected. On the Locking piston acts a restoring spring 29 supported on the cylinder head 6 Locking piston 26 is arranged transversely to the control piston 8 and can with a Project part of its length into the bore 7. The ring groove B is over a line 30, in which a pilot operated check valve 31 is installed, with the working space 5 connected. The annular groove A, on the other hand, is connected to the working space via a line 32 4 in connection.

An unlocking piston acting on the unlockable check valve 31 33 is in the unlocking direction from the pressure of the line 32 and thus the working space 4 applied. A compensating piston 34 arranged coaxially with the control piston 8 has approximately the diameter of the shift rod 17, acts on the shoulder 11 and is permanently subjected to the pressure of the working chamber 5 at its free end.

A channel 35 within the control piston 8 begins at the shoulder 10 in one in the end position of the control piston 8 between the annular grooves B and P area and ends in hole 14.

To explain the function, refer to the illustration of FIG. 1 assumes that there is pressure at the inlet connection 21. This pressure also prevails in the system P-A-32-4. Since at the same time the unlocking piston 33 of this pressure is loaded, the unlockable reverse valve 31 is opened. Consequently pressure medium flows into the working chamber 4, the piston 3 moves upwards and displaces pressure medium from the working space 5. The displaced pressure medium arrives via the unlocked check valve 31 via line 30, the annular grooves B and T1 and the channel 22 to the resistance valve 25, which for example at a Pressure of approx. 5 bar may open. After the resistance valve 25, the pressure medium flows essentially pressureless to the drain. The pressure of 5 bar is created over the channel 23 also continues into the working chamber 27 of the locking piston 26 and holds it against the Force of the return spring 29 in its extended position, in which the free The end protrudes into the bore 7. The preload of the spring 15 is dimensioned so that the pressure on the control rod 17 can not overcome it. The piston 3 will approach the control rod 17 in the course of its stroke and also touch it at some point. The spring plate 16 is then lifted from its stop and the spring 15 is further biased. The bias is transmitted to the control piston 8, the however, due to the locking piston 26 projecting into the bore 7, there is a movement is prevented.

The spring 15 is therefore further tensioned until the piston 3 is his Has reached dead center. From this moment on, no more pressure medium flows out from the working space 5 and consequently no occurs upstream of the resistance valve 25 either Back pressure more. Any pressure present can be reduced via the throttle 28, which was previously only allowed a small side stream to be dismantled. The return spring 29 is therefore able to overcome the locking piston 26 through the struc- ture piston 8 caused friction.

The pressure medium displaced from the working space 27 also arrives via the throttle 28 to the drain. The moment the free end of the If the locking piston 26 leaves the bore 7, the locking of the control piston 8 is canceled. The spring 15 suddenly relaxes against the force of the return spring 19 and pushes the control piston 8 into its other end position. Arrived from the inlet connection 21 the pressure medium now via the annular grooves P and B and the line 30 to the check valve 31, which opens automatically so that pressure medium flows into the working space 5. The piston 3 moves downwards. Pressure medium flows over from the working space 4 the line 32, the annular grooves A and T2 and the channel 23 to the resistance valve 25 and from there to the expiration. It must be noted here that the annular groove T2 without essential Change in function could also be directly linked to the process, provided that the Working space 27 would still communicate with the drain line 24. In the Downward movement of the piston 3 follows the control rod 17, whereby the spring 15 can relax again. The control piston 8 nevertheless retains its position, since the channel 35 has been switched with its opening in the area of the annular groove P. is and pressure medium has therefore passed under the control piston 8 and this hydraulically holds in position. The piston 3 therefore moves to its other dead position and remains stand there as long as there is pressure at the inlet connection 21. The control pressure before the Resistance valve 24 collapses, however, so that the return spring 29 in the the locking piston 26 can be retracted in the manner already described. It is now further assumed that by controlling an external valve, the inlet connection 21 is connected to the tank will. The pressure in system 21, P, B, 30 and 35 therefore collapses. The check valve 31 closes. The return spring 19 is able to move the control piston 8, wherein pressure medium via the channel 35, the annular groove P and the inlet connection 21 entweic} len can.

This process continues until the channel 35 is no longer with the Annular groove P is in communication. One caused by manufacturing tolerances or the like further stroke is made possible by leaks, it can be assumed that between two double strokes, e.g. when plowing, it takes a considerable amount of time. Will be another Double stroke necessary, the inlet connection 21 is again with the external valve Pressure applied. The pressure medium arrives on the route 21 already described, P, A and 32 in the working space 4 and sets the piston 3 in motion. The draining Pressure medium again generates a back pressure in front of the resistance valve 25, whereby the locking piston 26 is displaced until its free end is back into the bore 7 protrudes. This is possible because the control piston is hydraulically balanced and the channel 35 is not acted upon by pressure. A displacement of the control piston 8 is therefore actually only possible again when the piston 3 has reached its dead center has reached.

In Figure 3, a variant is shown in which the same parts have received the same reference number. Functionally similar parts have the same thing obtained with a prime numeral. One of the main differences lies accordingly in the fact that the free end of the locking piston 26 'has a bevel 37 which could have an angle of about 450. The control piston 8 'has a corresponding one Chamfer 38. The interaction of the chamfers 37 and 38 creates an axially directed one Force of the control piston 8 'in an acting against the dynamic pressure in the working chamber 27 Force deflected on locking piston 26 '. The return spring 29 supports this force in the sense of faster unlocking.

The restoring spring 29 could even be dispensed with in such a case. Faster unlocking is also achieved if the annular groove T2 has a channel 23 'is connected to the drain line 24 downstream of the resistance valve 25 and the work space 27 with the work space 5 via a in the direction of this work space opening check valve 39 is connected. Especially when the piston 3 'is moved by external forces or kinetic energy over the dead point, can Pressure medium escape from the working space 27 accelerated, since it is practically in the Working space 5 is sucked up. Another difference to the embodiment of Figures 1 and 2 consists in the arrangement of the spring 15 ', which is now in a bore 40 located within the piston 3 'and on a guide piston 41 works. The guide piston 41 is on an outward stroke by a snap ring 42 prevented, so that the spring 15 'always has a minimum bias which is sufficient the force of the return spring 19 and the resistance to movement of the locking piston 26 ' to be overcome, provided that the working space 27 is no longer acted upon by dynamic pressure. The power is transmitted from the guide piston 41 to the shift rod 17 ', which could be firmly connected to the control piston 8 '. In the event that the pressure supply line 21 cannot be relieved, it is advisable to place the channel 35 'in the area of the annular groove B open, so that a self-holding during the second lifting phase takes place, but later a better return of the control piston 8 'by the Return spring 19 is possible as soon as the shoulder 9 'has opened the annular groove T1, which is the case in a relatively short time due to leaks. The other function is the same that already described for FIGS. 1 and 2.

In FIG. 4, too, the same parts have been given the same reference numbers. If the function is similar, the reference number is given a dash or two dashes. In a bore 43 running coaxially to bore 7 is tightly sealed with an annular piston 26 " out with its outer surface, which with its inner jacket 44 on the shoulder 9 can slide tightly.

The annular piston 26 "divides a working space 27 'in the bore 43, which is permanently connected to the channel 22.

The annular piston acts on the side facing away from the working space 27 ' 26 'to three separate clamping pieces 45 which have conical surfaces 46, those with corresponding conical surfaces 47 of a plug closing the bore 43 48 cooperate in such a way that when acted upon by the annular piston 26 "they have a Apply clamping force to shoulder 9. The clamping pieces 45 are released after Elimination of the back pressure in the working space 27 'over a very short distance. A leak channel 49 connects the part of the bore 43 receiving the clamping pieces 45 with the annular groove T2. The check valve 39 in turn ensures rapid relief of the work space 27 ', which in the absence of external forces can also be relieved via a throttle 28' is.

The invention is not limited to the illustrated embodiments limited. In particular with regard to the locking of the control piston are manifold Variations are conceivable, with ball catches and pawls being mentioned in particular. The shape of the control piston, i.e. the number of its shoulders and waists is free, provided the function is retained. Also at the discretion of the designer the type of line routing and the design of the non-return valves and their Closing body.

After all, it depends on the external conditions, the possible ones Stroke of the spring plate or the guide piston before reaching the dead center more or choose less large.

Claims (11)

Designation: Control device for the automatic generation of a double stroke a double-acting piston-cylinder unit Claims: control device for the automatic generation of a double stroke of a double-acting piston-cylinder unit, especially for plow turning devices depending on a pressure increase in a feed line a) with a control piston for alternately connecting the a first and a second stroke phase effecting working spaces of the piston-cylinder unit with the inlet line or an outlet line b) and with an intermediate control valve and one of the working spaces, which can be unlocked and opened via an unlocking piston Non-return valve which acts on the release piston from the pressure of the other working space is, c) with a locking device acting on the control piston d) and one of the Piston actuated in the area of a dead center and acting on the control piston, characterized by e) a back pressure generating resistance valve (25) in the discharge line (24) of the working space (5) causing the second stroke phase, f) one of the control piston (8) soerrenden in an Endsteliunq, acted upon by the dynamic pressure Snerr piston (26,26 ', 26 "), its working space (27,27') at least when there is no back pressure through a relief opening throttle 28, 28 ') with the discharge line (24) downstream is connected to the resistance valve (25), q) a spring (15.15 ') for power transmission from the piston (3 ') to the control rod (17) or from the control rod (17) on the control piston (8), h) one the control piston (8, 8 ') in the opposite direction onerous weaker return spring (19) i) as well as a hydraulic one to the hzx * e one Self-holding beautschlagbaren, generating a force against the return spring (19) Effective area on the control piston (8,8 ') with a control line leading to this effective area (Channel 35,35 '), which are separated from the inlet connection (21) during the first stroke phase is and is in connection with the inlet connection (21) during the second lifting phase, j) where the force in the second stroke phase is greater than the force of the return spring (19). 2. Control device according to claim 1, characterized in that the Snerr piston (26) locks the control piston (8) positively and with a return spring (29) is provided. 3. Control device according to claim 1, characterized in that the piston (26 ', 26 ") locks the control piston (8, 8') in a non-positive manner. 4. Control device according to claim 2 or 3, characterized in that that the locking piston (26,26 ') is arranged transversely to the control piston (8,8'). 5. Control device according to claim 3 and 4, characterized in that that the Scerr piston (26 ') has a chamfer (37) or rounding at its free end, which cooperates with a corresponding chamfer (38) or rounding on the control piston (8 '). 6. Control device according to claim 3, characterized in that the locking piston is designed as an annular piston (26 ") and is coaxial with the control piston (8) is arranged and on at least two, preferably three, the control piston (8) surrounding, with conical surfaces (46) for transferring a through the annular piston (26 ") exerted axial force into a clamping piece equipped for clamping and serving radial force (45) works. 7. Control device according to claim 6, characterized in that the clamping stroke of the ring piston (26 ") against the switching direction caused by the spring (15) of the control piston (8) takes place. 8. Control device according to one or more of the preceding claims, characterized in that the spring (15, 15 ') is biased. 9. Control device according to claim 8, characterized in that the spring (15) is tied in a bore (14) inside the control piston (8). 10. Control device according to claim 8, characterized in that the spring (15 ') is tied in a bore (40) in the piston (3'). 11. Control device according to one or more of the preceding claims, characterized in that the drain lines (channels 22 and 23) of the working spaces (4 and 5) of the piston-cylinder unit are located downstream of the resistance valve at the earliest (25) and the working space (27,27 ') of the locking piston (26', 26 ") with the the second stroke phase causing the working space (5) via a in the direction of this Working chamber (5) opening Rückohlaqventil (39) is connected.