DE1528583A1 - Hydraulically or pneumatically continuously operated piston drive with reciprocating movement, especially double-acting pressure intensifier - Google Patents

Description

St. Ingbert, the 18th Y * 1! 965

Applicant: Stahl- und Apparatebau Hans LEPFER C. I. .H., Dudweiler / Saar, Pfählerstraße 1

"Hydraulically or pneumatically operated continuously Piston drive with reciprocating movement, especially double-acting pressure intensifier "

The invention relates to a hydraulic or pneumatic piston drive with reciprocating movement, in particular a double-acting pressure booster, in which the movements of the low-pressure piston in the end positions zurr the control pressure; Influencing change of direction. Although the invention does not apply to pressure intensifiers, but can be used in the same way in most exemplary embodiments, for example also for hydraulically or pneumatically operated motors , reference is usually only made in the following to double-acting pressure intensifiers.

Of the double-acting pressure intensifiers, their reversal without If electrical aids are used, two solutions are known. the first solution is that of the reciprocating, double-acting differential piston by means of one to the low-pressure piston articulated and through one of the two covers by means of a stuffing box to the outside led through auxiliary piston rod, a four-way slide is actuated, which worries the reversal. So in the switchover abruptly at both end positions, even when running slowly takes place, the four-way spool is mechanically locked in both of its end positions so that the switchover only takes place after a sufficient large adjusting force is carried out by a spring-actuated switch. A similar solution is to do the reversing of the four-way spool is effected by the high pressure piston instead of an auxiliary piston. 909885/0472 - '

_2- 8AD ORIGINAL

In this case, the low-pressure and high-pressure cylinders are not assembled directly, they are spatially separated from each other by a lantern, the high-pressure piston running outdoors in the area of the lantern causing the mechanical reversal of the four-way valve with the help of attached cams, with one here too spring-actuated spring switch is required. Instead of the purely mechanically actuated spring switch, an intermediate pilot valve can also be used, which in turn controls the main travel valve.

This predominantly mechanically delayed reversal is structurally complex and prone to failure. Much more reliable is the two ce solution in which ^"1, the reversal is effected by hydraulic means, and predominantly from which the invention starts out.

Au ^f * the field of double-acting Lui'tmotore is known for the reversing, Dab the movements of the ArbeitskclLens in the end positions of the control pressure of a pulse-controlled, ie * controlled -by pressure relief Vierwegeventj 1-3 diminish _s in which both sides of the control slide arranged " Control rooms connected to the pressure source lead to the 8-part entrances.

Another Ar + · from LtiitiriOtoirm has the usual, vom Working piston mechanically operated three-way pilot slide for steering of the four-way valve duroh idrifaehe two-way pilot valve replaced, By having the constant pressure on the two control rooms of the Four-way valve instead of the three-way pilot valves through auxiliary bores in the control slide or in the valve body of the four-way valve has ensured that the pressure source with the two control rooms associate.

This circuit also has the disadvantage. that it fails when the working piston creeps. The reason for this lies in the fact that the pilot valves also open very slowly when running very slowly, so that the pressure relief of the control chambers in the end positions takes place gradually.

'■ -3- 909885/0472 BAD

slowly moving the spool into the opposite end position begins to wander and stands in the middle position r'.eibt, because the pressure difference is not sufficient for the further resistance to movement to overcome. Since depending on the design of the slide in the middle position

a) the pressure connection and both cylinder connections are complete or

b) the pressure connection is closed and both cylinder * connections are depressurized,

the low-pressure piston stops and the pilot valves stop in the degree of opening in which they are currently located.

The invention has set itself the task for continuous Piston drives of the type mentioned at the beginning by simple switching means to cause a switchover delay. -'r - similar to the well-known snap action or throttling in control lines prevents the piston drive from stopping when the gear is creeping, on the other hand, however, he does not stop quickly as can be the case with throttles in the uuerleitunken.

The invention has two approaches, the first of which for the reversal of the operating pressure in a known way a pulse-controlled four-way valve, the second solution instead two three-way valves special design includes, which are controllable both by pressure relief and by pressurization.

The measures according to the invention exist within the scope of the first solution to the changeover delay in the fact that in the valve covers of the four-way spool The bores located at least in the end positions of the control slide are always open, and the end faces on both sides of the control spool, two each in different levels Have control surfaces, one of which is in the end positions, the first control surface both via a throttled line to the pressure source as

909885/0472

BATH ORIGINAL

is also connected to the outgoing control line and the other, "estliche control surface is relieved from the first control surface through the hole in the Vent:! Lieckel under sealing in the end positions, whereby the seal is effective on a limited, ineffective path of the reversed control slide The switchover delay takes place in that when the pressure is released on the side of the control piston that is fully pressurized, a movement of the steamer piston is only initiated after a certain pressure drop, and only part of the control surface, namely the first control surface, is applied on the other side ...; ■>: · ..,> e remaining area but relieved Sets the movement of the control piston one, this does not yet change the operating pressure, then the residual surface lifts from the Abdicrf ¹ -ig-τ from which she is additionally acted upon and a sudden force difference arises on both oppositely acting total control surfaces, de r suddenly reverses the control spool.

It is essential in the invention that in the end positions of the control slide of the four-way valve partial areas of the front control surfaces are relieved and after a small return path for additional Loading can be switched on.

The second solution with two three-way valves of a special design is based on the same principle. According to the invention, a piston drive is reversed, in which the reciprocating movements of the working piston in the end positions change the control pressure, with the help of two hydraulically controlled three-way valves, the control slide of which has a differential piston with an annular surface constantly acted on by the operating pressure and a frontal control surface Control room on the one hand via a small diameter hole in the control slide with the pressure source and on the other hand with a Steuerlei tvne; See in connection with the small diameter bore in

909885/0472

the end position of the control slide, "in which the valve is opened towards the piston drive, is blocked, with a passage is kept open, through which a smaller one when the control room is depressurized Leakage current flows, which builds up a pre-pressure in the control room when the control line is shut off

each three-way valve to one of the working spaces of the piston drive opposite pressure ratios are set compared to the associated control line. The small diameter bore runs expediently in a piston-like projection of the frontal control surface, which in one end position of the control slide through contact of its ΊLoht flat with the valve cover up to the hole blocks a radial notch in its end face. This ensures that the pre-pressure that builds up in an end position due to the leakage flow only initiates an adjustment of the control slide with a delay at a certain pressure given by the differential piston effect until the remaining sealing surface lifts off the valve cover and over the now fully opened bore in the control slide, which is connected to the pressure source, is additionally acted upon. Here, too, this sudden difference in forces on the differential piston causes a sudden reversal of the control slide.

Allow the measures according to the invention on the reversing valves with both solutions, simplifications in the way and catfish, like the Changes in the control pressure ·· duroh dl · Movements of the working piston the piston drive can be triggered. These simplifications are in explained in more detail in the following drawing. .

In the drawing, the invention is duroh circuit diagrams in several Exemplary embodiments of double-acting hydraulic pressure translators shown, namely show:

1, 2, 4 and 5 circuit diagrams with a four-way valve according to the

,. ereten solution * weg, 009885/0472 '■'

■ '■■■' ■ t ■ ■ * ■

Flg _# J a detail there, too,

BAD OR) GJNAL

Figures 6 and 8 are sectional views of the four-way

vent reads

Pig. 7 a circuit symbol of the four-way valve,

9, 12, 13 and 15 circuit diagrams with two three-way valves

according to the second solution,

Fig. 10, 1Ϊ and 14 details, and

16 and 17 are sectional views of the three-way valves

in two different control positions.

The continuous piston drive, in the examples hydraulic, double-acting pressure intensifier, consists, as is known from FIG. 25 and the high-pressure pistons 26, 27, which represent the piston rods during engine operation. The high pressure is alternately supplied to the consumer via check valves 28, 29 in lines 30, 31. Via check valves 32, 33 in lines 34, 35, the high-pressure pistons 26, 27 can suck in pressure medium during their return strokes. The lines 34, 35 are via a four-way valve 36 (Fig. 1, 2, 4 and 5) or two three-way valves 37 * 38 (Fig * 9 * 12, 13, 15) alternately to the pressure line 39 or the RUc flow line 40 to the collecting container 41 switchable, via the branches k2 _t 43 the working spaces 22, 23 of the low-pressure cylinder 20 are alternately acted upon and connected to the return. In this respect, all circuit diagrams are the same. Furthermore, the state of the individual rooms is marked in all circuit diagrams by (p) or (0) to indicate that the pressure ρ or zero prevails there.

First, the measures according to the invention ata four-way valve 36 are explained with reference to FIGS. 6 and 8. The SteueracUiebej * 45 has at its both end faces a central _{piston-t-like} projections 45a, which .als residual area designated end surface F ₂ of the remaining annulus "

. "909885/0 A 72

-7-

shaped inherited ^r ·! evierflache F. vorgelagerr. · There are very small bores 46, 47 in the valve covers, which in Fig. 6 are constantly depressurized and in Fig. B only in the end positions of the control slide 45. Round rubber seals 4-8 are arranged in the two covers of the valve body, which cover the remaining area F 1 of the control slide 45 in one end position, the space inside the seals being vented to the outside through the bore 46 or 47.

The two-sided control chambers 50, 51 of the valve 36 are constantly connected to the inlet or the pressure line 39 via auxiliary bores 52, 53 in the control slide. In FIGS. 6 and 8, the control surfaces F and Fp on the left side are acted upon as a whole, with only a little pressure medium escaping through the small bore 46. On the right-hand side, however, only the first control surface F. is acted upon, <": > Ue remaining area Fp blocked by the elastic ring seal 49 and relieved st. As a result, the control slide 45 has a stable end position, since the force p. (F . - <F ₂ ) the opposing force working from the right ρ , F. £>& ι / nübersteir

If the pressure on the side of the greater force, than u . - ..: n '^ room 50, is reduced all round, after an initial ineffective return of the control slide 45 during the elastic resilience of the ring seal 49, the switchover only takes place when the Pressure under dc-r. '■ ei't ρ - F2 has decreased. The one right now

F ₁ + F ₂

Additional displacement force released due to the connection of the remaining area Fp has the amount ρ · F ₂ and causes a sudden displacement of the control slide 45 into the opposite end position. The displacement force available increases just like the displacement resistance proportionally with the working pressure ρ. It is also advantageous here that the sealing rings 48, 49 in the end positions reduce the speed of the control spool to zero without jerking.

' ^digits 909885/002. Copy

BATH ORIGINAL

Flg. 6 thus shows a possible embodiment of the four-way valve 36 controlled by pressure relief pulses with switchover _{delay by switching off the remaining areas F 2} by means of the small bores 46, 4γ in the valve covers. Fig. 8 shows an embodiment in which the pressure relief of the surfaces Fg is brought about by the control slide 45 and when the surfaces F and Fo, for example, the bore 46 is shut off via the line 54 to avoid a leakage current when the surfaces F and Fo are fully loaded. /'..·Π .- / orden illustrated by the switching symbol according to FIG. 7, in which the forces delaying the switchover are indicated by arrowheads. The auxiliary bores 52, 53 in the control slide 45 are replaced here by dashed lines with built-in throttles 55 * 56.

Returning to Fig. 1, two 7w-IwegepiIotschieber 63, 64 built into the control lines 60, 6l serve to apply the pressure relief pulses for reversing the four-way valve 36, which are closed by spring force in the idle state and in the end positions by the working piston 21 of the piston drive by means of the plunger 65 » 66 are opened mechanically, the pressure relief of the control chambers 50, 51 of the four-way valve in the pressureless .Außenraum or in the collecting container 41 takes place.

In the circuit according to FIG. 1, a further simplification is possible, which consists in relieving the pressure of the four-way valve 36 directly into the collecting tank or into the pressure-free space instead of the control pressure, the same into the respective pressure-free spaces 23 and 22 respectively relieved. This is possible because the operating pressure ρ penetrating into these rooms after the reversal has taken place no longer reverses the direction can be reversed, since the control room of the four-way valve on the opposite side is closed, so none Impulse effect can occur. This makes it possible, as can be seen from the figure, to use simple, spring-loaded

5/0472 "ßAD ORlGiNAL

• -9- ■ ■ ^': ■ ■:

Loaded check valves 67 * 68 to replace those in the end positions are pushed open by the low pressure piston 21 and are closed by spring force after reversing the direction * If you now go to it about using the high-pressure pistons 26, 27 for reversing, so you can use the circuit according to Flg. 1 by simplifying - as shown in Fig. 2 - on the left and right side of the translator in the pressure body two diametrical bores 69 and 70 attaches, of which the holes 69 with the left and right control chamber 50, 51 of the four-way valve, the holes 70 with the Collecting container 4l or the pressure-free outside space are connected. Each high-pressure piston is provided with an annular groove 71 "72" each in the left and right end position, the bores 69 and 70 connect to one another, whereby the pressure in the control chambers of the four-way slide valve is relieved and the reversal is brought about. Since in the Bores 69 a unilateral pressure. Exerted on the high pressure piston this solution is only recommended for compressed air drives because

here the pressure is mostly below 10 kg / cm. Since the diameter of the Bores 69 is small and, moreover, when the translator is in a horizontal position, the weight of the high and low pressure pistons acts in the opposite direction, the weight components are partially compensated. One can apply the unilateral pressure on the high pressure piston avoid if instead of the bores 69 and 70 according to FIG. 3 adjacent ring caramers 73, 74 are provided which are in the end positions with correspondingly wider ring grooves 71, 72 or longitudinal nuts 75 in the high pressure pistons 26, 27 are connected to one another.

In the same way, the circuit according to FIG. 4 can be simplified, in that the high-pressure pistons 26, 27 are also used here for reversing, as shown in FIG. 5. This is achieved by that the control lines 6l, 62 of the four-way:; nhtebers 56 are connected on both sides with annular chambers 78, 79 screwed into the pressure body,

809Ö85 / 0472 -

-10- 'BAD ORIGINAL

which are controlled towards the end of the stroke that the

on the diameters d3 turned off areas 80, 81 d ^ r high pressure piston 26, 27 move into the annular chambers 78, 79 and establish the connection to the respective pressure-free spaces 23 and 22, whereby the reversal of the four-way valve 36 is effected. The measures described above according to Pig. 2 to 5 for saving The pilot wheel 63. 64 can also be used independently of the inventive device Switching delay will be applied when this delay not necessary if the pressure intensifier is running fast enough is,

E3 sej also noted that one can use the pressure intensifier in a simpler way Way eirj »and can be switched off by opening and closing one (not shown) through valve, which in one of the two Control lines 6l, 62 is installed.

If one compares the final results of the first solution, namely the circuit diagrams according to FIGS. 2 to 5 with the initial situation n & jh Pig. 1 the progress made is clearly visible. In addition to the won Switching delay, the circuit is greatly simplified, the Piiot sliders are completely suppressed and with them all eccentric forces acting on the differential piston. The omission of the springs also increases operational reliability. as In the circuit according to FIG. 5, drive media are both pressurized gas also pressurized fluid in the same way suitable during the circuit according to Fig. 2 is only suitable for propulsion by compressed gas.

In pursuit of the second approach, let us first consider the three-way valve 37 »38 special design described ^ which according to the invention to the Step in place of the four-way slicer 36. Each of these sliders consists 16 and 17 show, from the valve housing 90 with the connections IN, OUT, CYL and the "t your connection? · 91.

909885/0472 _o -

· ■ -H- ⁶ ^ D OPdGiNAL

Control slide 92 designed as a differential piston with the face <* n surfaces F1, F2 and the annular surface F1-F2 can assume two stable positions. If the control pressure p _sfc = 0, ie if, according to Fig. 17, the control line 93, 9 ^ (Fig. 9) is depressurized, the pressure ρ acting on the annular surface F1 - F2 presses the control slide 92 against the cover 95 of the control chamber 96 The bore 97 with the diameter d, which connects the annular surface F1 - F 2 with F 1, is closed by an end-face sealing surface of a piston-like projection 92 on the control surface F1 into which the opening 97 runs out. However, a small notch is worked into this sealing surface so that in this position a small leakage current can flow off via the unpressurized control line 91, 9h.

The second stable position according to FIG. 16 is given when the control line 95 is under the pressure ρ -. = ρ stands. Since the two surfaces F ₁ and F. - Fp are under the same pressure ρ, the control slide 92 is pressed into the opposite end position, with the now exposed bore 97 for Druckgleiehhci, ^ n both spaces.

The switching distributions assigned to these two positions are illustrated in Figures 9, 12, 13 and 15 by the symbols, where the state of the connections is identified by the designations (p) and (o) to indicate that there the pressure ρ and the There is pressure ο.

Switching from the state according to Fig. 17 (valve 38 in Fig. 9) in the state according to FIG. 16 takes place through the termination of the control line 91, 94. The through the notch in the sealing surface of the projection 92a flowing Leekstrom caused because of the small volume of the closed A rapid increase in pressure. At this moment,

T? L - ff?

in which the control pressure has the value p _Q. * ρ. ^ - - over-

bt _pi

progresses, the control piston is in an unstable equilibrium. As a result, the sealing surface lifts up, and that through the bore

909886/0472,. _,

- ¹² - BAD OfUGHNAL

97 flowing medium pushes the control slide 92 accelerated

in the opposite stable end position. ι

Conversely, the changeover from the state to Flg takes place. 16 in the state according to Fig. 17 by opening the control line 91/93. * At the moment at which the control pressure exceeds the limit value p _{o +} . -

Fl - F2 ■

ρ. _ falls below, the control slide moves accelerated into the other end position, displacing the medium located in the control chamber 9β and flowing through the bore 97 during the switching process until the bore 97 is almost closed again by the sealing surface in the end position. What is important for the suitability of this three-way valve is the special property that in the control line 93 or 94 and in the outlet 42 or 43 to the cylinder 20 there are always opposite pressure conditions, ie if the control line 9 ^ is depressurized, the outgoing cylinder line 42 is under pressure and vice versa. This is set by the connections 98, (Fig. 0) .

The switchover of the pressure intensifier shortly before reaching an end position can be initiated

1. ', by relieving the pressure in the control room of one of the two three-way slide valves 37 * 38, *

2.) by pressurizing the "control chamber of one of the two three-way spool ^1,.

First, let the circuit Flg. 9 explained in more detail, in the case of the use is made of the option mentioned under 1}. During the stroke of the working piston 21 to the left, the control space 96 is des Three-way valve 38 depressurized via lines 94.99 * 43 while the control room 96 of the three-way valve 37 via lines 93 * 98, 42 is under the pressure ρ. Since the two associated two-way pilot slide 100 and 101 closed by spring force during the stroke remain, the lines 98, 99 ensure that this state is maintained by the control rooms with those

_B. , _D

Connect lines 42, 43 to the low pressure cylinder 20, which / 'have the same potential.

The reversal takes place in the left end position of the working piston 21 by mechanical actuation of the pilot slide 100, whereby the control room of the three-way vehicle, 37 depressurized and 'The working space 23 is exposed to the pressure. Simultaneously is via line 99 of Sieu ·: * ra> £ three-way valve 38 put under pressure, whereby this is reversed and the working chamber 22 is relieved of pressure. After reversing the motion circuit the pilot slide 100 is returned to its rest position by spring force, but the control line 98 ensures that the The control chamber of the three-way slide valve 37 remains pressure-relieved until the next switchover. The two-way pilot decals 100 and 101 can be designed according to Fig. 10, the spring force must in any case be greater than that acting on the opposite side of the piston Compressive force. Instead of the spring force, a slide with return through differential pistons according to FIG. 11 can also be used.

If one also goes over here to -use the high-pressure pistons 2β, 27 with?, For reversing, so -rgü ^r . si oh the circuit according to FIG. 12, in which the control chambers connected to the bores 104 are relieved of pressure at the reversal points in that the annular grooves 105 screwed into the high-pressure pistons establish the connection to the bores 106, which in turn connect to the collecting container 41 or the pressure-free space are connected.

The switchover by applying pressure to the control chamber of one of the two three-way slide valves 37-38 is shown in the circuit according to FIG . . _;

Ale Pilots chi elvtr <X $ eäf, more precisely, act as a pulse generator ,

in dle & ee fl ^ jj & fr Vffci asifc? ^^ rr $ öifcftöirufl $ - provided piston 108, 10 $ '-17

with a continuous axial bore, which in the reversal points through the low-pressure piston 21 of the pressure booster be operated. In doing so, the axial bore is first closed and then the medium located in the cylinder 110 is compressed. A possible embodiment of this pulse generator is shown in FIG. 14.

The control line 9 ^ of the three-way spool 38, which leads to the Arbeitsra'iri L-: -ru '' -, '., Is connected to the unpressurized space 23 via the cylinder 110 and the duich-bored piston 108 of the transmitter , whereas the control line 93 of the Three-way slide valve 37 'which relieves the pressure in the space 23 and is connected to the pressurized space 2k via the transmitter with the piston 109. In this way, the positions of the two three-way slides are locked against each other. If, towards the end of the stroke, the piston 21 of the pressure booster moves against the transmitter 108, HO ₃ , the associated control line 9k is closed and, if the speed is sufficient, a pressure surge

Fl - F2

generated, this pressure surge exceeds the value ρ. -

Fl

the control slide of the DrelwegeseMübers 38. is lifted from its seat 92a and the Mueratröroenäe Meaium through the exposed hole 97 in the control room 96 pushes the K. al bon accelerated into its

IT)

D: u S '. ^; ■ ii; si ο; .

w \; 10: Kk, 1ε ..:

ί-Ί hi il i Γ: /

uck in this room: de.rn moment,.,. ohreitet, moves Hi ".? ;; uaIgt in his -, r> υ, -tor pressure, .-: '■■■) is reversed

... ■■. Control pressure cn \ ier control chamber ■ s,

BATH ORIGINAL

Tf: *: he: ".-Mf: cii ¹ ^ e""Movement the speed of the translatorerkojrtiu 21 jei-vi-; .o &■■;'ing, daC after completion of the axial drilling of the.

Calving's ICP does not have a sufficient pressure surge, that is enough through the notch in the sealing surface 92a of the three-way valve 28 flowing leakage current to its control chamber 96 quickly enough

to the limit value ρ and thereby reduce the

Pl

initiate control. Another significant simplification leaves here, too, by the fact that the high-pressure pistons 26, is also used for reversing by - as shown in the circuit diagram Fig. 15 - the pulse generator is replaced by the two Arranged concentrically to the piston rod in the manner of damper bars ..., Neten control chambers 112, HJ.in before reaching the respective He j Ir ge retract the approaches 114, II5 of the high-pressure piston, whereby exactly the same reversal effects can be achieved as with the To / or · Described random pulse generators.

- patent claims -

BADORlGiNAt

909885/0472

Claims (1)

PATENT CLAIMS 1. A hydraulically or pneumatically continuously actuated piston actuator with reciprocating movement, in particular double-acting r pressure intensifier in which the movements of the Niederdr .. ·· kkolbens: n the end positions of the control pressure of a pulse-controlled four-way valve reduce, arranged in its both sides of the control slide, The control lines open with the pressure source in connection with the control rooms, characterized in that there are bores (46, 47) in the valve covers which are constantly open at least in the end positions of the control slide (45), and the two-sided end faces of the control slide each have two in have control surfaces lying on different levels, of which in the end positions one, first control surface (P ₁ ) is connected to both the pressure source and the outgoing control line (61,62) via a throttled line (52,53) and the other , remaining control surface (P ₂ ) under ge in the end positions sealing compared to the first control surface (F ₁ ) is relieved through the bore (46, 47) in the valve cover, the seal being effective on a limited, ineffective path of the reversed control slide (45). 2. Piston drive according to claim 1, »characterized in that the remaining surfaces (P ₂ ) of the control slide (45) in the four-way valve are formed by central, piston-like projections of the end faces of the control slide, the end faces of which are upstream of _{the remaining circular first control surfaces (F 1),} In the end positions against elastic ring seals (48, 49) embedded in the valve cover, the seals of the relief bores via a dependent on the elasticity of the ring seals cause ineffective return travel of the control spool. 3. Piston drive according to claims 1 or 2, characterized in that that the throttled lines between the pressure source and the control chambers on both sides of the control slide In . As is known, auxiliary bores (52, 55) are formed in the control slide (45). ^ "^ | & / $ H * l Ε.ΛΟ ORIGINAL Piston drive according to Claims 1 to 3, characterized in that that the pressure relief pulses from in the control lines , (61, 62) arranged two-way pilot slides (63 »64) are applied, which are closed by spring force in the rest state and be opened mechanically in the end positions by the working piston (21) of the piston drive, whereby the pressure relief of the control chambers (50, 51) of the four-way spool (36) in the unpressurized Outside or into the collecting container takes place. (Fig. 1) Piston drive, in particular according to Claims 1 to 3, characterized in that the control lines (61, 62) through into the High-pressure pistons (26, 27) or annular grooves (71, 72) incorporated into the piston rods of the piston drive can be controlled towards the outside are. (Fig. 3 »2) Piston drive, in particular according to claims 1 to 3 »characterized in that the control lines (61, 62) are spring-loaded Check valves (67,68), which are opened mechanically by the working piston (21) of the piston drive, against the respective pressure-free working chamber of the piston drive can be opened 7. Piston drive, in particular according to claims 1 to 3, characterized characterized in that the control lines (6l, 62) via the high pressure piston (26, 27) or annular chambers (78) surrounding the piston rods of the piston drive and grooves (80) in the high-pressure piston or the piston rods against the pressure-free working space of the Piston drive can be opened (Fig. 5). 8. Hydraulically or pneumatically continuously operated piston drive with reciprocating movement, in particular double-acting pressure intensifier, in which the movements of the low-pressure piston change the control pressure in the end positions, characterized in that the reversal with the help of two hydraulically controlled three-way valves (37, 38), the control slide (92) of which has a differential piston with an annular surface (F1 - F2) and one that is constantly acted upon by the operating pressure frontal control surface (92a), the control space (96) of which one, on the other hand via a small-diameter hole (97) in the control slide with the pressure source and on the other hand with a control line (91 * 9 ^) communicates, the bore being small Diameter in the collar position of the control spool in which the valve 909885/0472 ' .Ig. CAD ORIGHNAL ■. \ is opened towards the piston drive, is shut off, with ei. 'v. ■. '. .> iig is kept open, through which a small leakage current flows when the control chamber is depressurized and which builds up a pre-pressure in the control chamber (96) when the control line is shut off, whereby in the outgoing line; . '. \ 2, 0) of each three-way valve (37, 38) to one of the working spaces of the piston drive with respect to the associated control line (93, 9 ² O opposite pressure conditions are set. (Fig. 9, 16, 17) 9. Piston drive according to claim 8, characterized in that the drill mast (9 ") of small diameter in the control slide (92) of the three-way valves (37, 38 _{) expires in a piston-like projection of the frontal control surface (F 1} ), which is in one end position of the The control slide closes the bore through contact of its sealing surface with the valve cover (95) except for a radial notch in its end face (Fig. 17) * through which the leakage flow passes. 10. Piston drive according to claims 8 or 9, characterized in that the three-way valves (37, 38) can be controlled by relieving the pressure of the respective pressurized control line (939 ² O of a valve and the control line of one valve with the outlet line (42, 43 ) of the other valve is connected to the respective working chamber of the piston drive (Fig. 9) 11. Piston drive according to claims 8 to 10, characterized in that in the control lines (93, 94) of the three-way valves (37, 38) two-way pilot slide (ICO, 101) are arranged, which are closed by spring force in the rest state and through in the end positions the working piston (21) of the piston drive can be opened mechanically, the pressure relief of the control chamber of the associated three-way valve being carried out into the depressurized outer space or into the collecting container (FIG. 9). 12. Piston drive according to claims 8 or 9, "characterized in _o that the three-way valves (37 * 38) by pressurizing the respectively non-pressurized control conduit (93 '94) of a ο Valves are controllable by connecting the control lines to the cylinders π of pulse generators (108-111 ) are connected , which are in the end positions ^ voa working piston of the piston drive are mechanically operated (Fig. 13, 10, 11)
j l3 · Piston drive according to claim 12, characterized in that the ■ pulse generators from «4th, 4th cylinder covers of the piston drivef arranged cylinders (110, 111) with a spring-loaded, through- - * ~ - - " ι, ί ~ ^1Q "CAD ORIGINAL" drilled and consist of the working piston (21) of the piston drive mechanically operated pressure pistons (108, 109) in the end positions, whose longitudinal bore is blocked by a cover in front of the end positions. (Fig. 13) 14. Piston drive according to claim 12, characterized in that the pulse generator from concentric to the high pressure piston (27, 28) or the piston rods of the piston drive arranged annular chambers (112, 11?) exist in the piston-like in the end positions Approaches (114, 115) of the high-pressure pistons or piston rods closing retract (Fig. 15). 15. Pressure-medium-controlled changeover valve with oppositely acted upon control surfaces, in particular for a piston drive according to one or more of the preceding claims, characterized in that at least one of the end faces of the control slide (45,92) in a first continuously acted upon control surface (F,) and a remaining Control surface (F ₂ or 92a), which is switched off in the end position of the control slide by sealing interaction with the valve cover and relieved via a bore (46, 47 or 91) in the valve cover until a control surface ( F. + F or F ₁ - F) the onerous pressure has dropped so far that the force acting on the first control surface predominates and, due to the delayed reversal movement of the control slide, the remaining surface (F ₃ or 92a) of the first control surface (F, ) is switched on, after which the reversal takes place suddenly. 909885/0472 Blank page