EP0961037B1 - hydraulic actuator with locking mechanism for end of travel - Google Patents

Abstract

The piston (1) is positively locked in a cylinder (3) at stroke end, by locking elements (4). For each end position, there are locking elements, a pretensioned locking piston (6), and a locking element carrier (7), which are all positioned within the ring chamber between piston rod (2) and cylinder. The locking elements are not spherical. The space for the tension spring (5) for the locking piston is relieved to the opposite working chamber via a channel (12) and a valve (13). All required components are of modular construction.

Description

The invention refers to a hydraulic Working cylinder with an end position lock, in particular plunger and Differential work cylinder with an also guide side Locking in the higher pressure range. The invention can be applied in all areas of fluid technology which in the end positions of the working cylinder a mechanical Lock is necessary.

After the IPC (International Patent Classification) will be Pressure-actuated actuators classified in the F15B. The locking of fluid operated devices is specifically classified in the F15B 15/26.

The most commonly used with optimal material utilization Piston rod ratio PHI is hydraulic Working cylinders in the range of 1.6 to 2.5.

d₂: Kolbenstangendurchmesser

d₁: Kolbendurchmesser

It generally applies: d 2 = d 1 PHI -1 PHI With

d ₂ : piston rod diameter

d ₁ : piston diameter

It is therefore for hydraulic differential working cylinder with a piston diameter also given piston diameter set at a certain interval and is usually not below or exceeded. Previously known solutions for locking are constructive way designed that they are useful primarily only applied on the ground side be, since the solution principle when applied in Rod guide area would have radial expansions result the one technically feasible solution from the point of view excludes commercial exploitation. Previously known Locking solutions use constructive Reasons for a one-sided locking mostly a piston rod ratio PHI outside the technically and commercially acceptable range.

For a blocking hardened steel ball results in a

p

Hertz'sche Pressung

F

axiale Kraft auf die Kugel

E

Elastizitätsmodul der mit der Kugel gepaarten Teile

r

Radius der Kugel

welche aus der Erfahrung den Wert von p=900 N/mm² nicht überschreiten sollte.Hertzian pressure after

p

Hertzian pressure

F

axial force on the ball

e

Modulus of elasticity of the ball-paired parts

r

Radius of the sphere

which from experience should not exceed the value of p = 900 N / mm ² .

The commonly used balls therefore have opposite in surface contact pressing locking elements a principle disadvantage at high pressures due to the maximum permissible material load limits.

Another significant feature of previously known solutions for locking is that the coupling of the Locking system is usually done on the piston rod, which is the available stroke decreases and the use of the piston rod for additional functional units on the working cylinder impossible (limit switch, position measuring device). One Another problem is in the caused by leakage Locking the locking system to see. Fills over a longer period of actually completed space the biasing locking piston spring with the used Pressure medium, unlocking is no longer possible since the same the movement of the locking piston opposes.

In the document DE2911071C2 a lock for Working cylinder with an annular locking piston (7) designed to lock the locking elements (8), which is applicable only on the bottom side, as the management side not enough space for the blocking required Parts, in particular the preloaded locking slide (20), is available or the management side conclusion part disproportionately mass-intensive.

In the document DE3540277 a self-locking, double-acting cylinder executed in which a Differential piston axially displaceable on the one hand at his Outer diameter in the housing and on the other hand with its inner channel is mounted on a housing-fixed socket, wherein a locking piston, on the one hand in the differential piston and on the other hand is mounted in the socket, the ball lock actuated. In this cylinder to move within the housing three components relative to each other, resulting in a relatively complicated structure.

Known is a lockable cylinder with a few movable locking parts from the publication DE3732561C2. In this case, locking parts between recesses the piston inner shell and the cylinder outer shell pressed, which take over the blocking. Located to itself a locking piston, which via a spring is biased, inside the working piston. This principle However, for design reasons, only for the bottom side Latches applicable, since the guide side in the Piston rod no locking piston is integrable. moreover are here as locking elements exclusively Balls applicable, with the disadvantage of line contact the same at the blocking and thus extremely high Hertzian Pressing, which makes this system only at low hydraulic Press is applicable.

In the document DE 39 42 348 C2 is a in the end position Lockable working cylinder with a preloaded locking piston described in which an integrated into the piston Kugelgesperre in a receiving this annular Recess of the bottom or the locking piston is locked. The centrally located locking piston itself is biased and is optional within the Piston (Fig. 3 and 4). The disadvantage of this system is that a management-side execution of this solution is not is possible.

In the document DE 34 28 228 A1 is a in both end positions lockable working cylinder disclosed in which the respective Kugelgesperre are integrated in the piston and the locking against the cylinder tube takes place, which undergoes a special training by so-called flange rings. The locking piston for positive locking The balls will be inside the hollow piston rod axially guided and actuated by a separate control pressure. A disadvantage is the arrangement of the locking piston within the piston rod, as this only small forces over this transferable, whereby this arrangement for the high-pressure area is unsuitable or other applications the piston rod is not possible.

From document FR-A-896 839 is a device for locking known from working cylinders, the -am working piston radially movable locking segments with inclined Having contact surfaces, in cooperation with inclined Contact surfaces of an axially displaceable on the working piston Locking piston and under the effect of Engage pressure in a recess in the working cylinder.

To unlock a pressure medium must be supplied, the shifts the unlocking piston against a spring preload. The unlocking piston and the working piston are at the same time subjected to pressure, whereby the locking segments against the existing blocking force from the Slip out recess in the working cylinder. At the moment the complete unlocking is the full working pressure of the medium at the working piston and it inevitably comes to a brief, jerky movement when extending or retracting the piston rod.

The same disadvantage has in the document DE-C-719 409 Verstellstrebe described, the working piston has transversely mounted locking members, the means of a working piston under the action of the pressure medium axially displaceable locking piston in the End positions of the working piston via expansion rings with annular grooves interact in the cylinder wall. To unlock a pressure medium is supplied to the working piston and via channels in this, at the same time on the locking piston acts. The locking piston is moved, so that the locking members by the bias of the Spreader rings are pushed back and the engagement of the Spreizringe is lifted with the grooves. Because the piston already charged with the pressure medium, the drives Verstellstrebe jerky off.

The object of the invention is to realize a on the guide side and / or bottom side usable Endlagenverriegelung a working cylinder that provides a smooth start guaranteed from the locked end positions. basics Aspects provide separate modular detachable locking units and an optional usability of the piston rod for additional system solutions. Another essential Aspect lies in the usability of this realization even for the higher one Pressure range, as well as in the exclusion of function-inhibiting Leakage problems.

The object is achieved by those listed in the protection claim 1 Characteristics solved. Preferred developments emerge from the dependent claims.

The essence of the invention lies in the complete integration of the piston and the end position locking required Construction parts, - the locking elements, the prestressed Locking piston and the locking element support - within the annulus between piston rod and cylinders. In differential work cylinders is a such arrangement executed flipped on the piston.

The locking elements engage in the cylinder inner shell - Preferably in the field of caps - a. The release of the locking elements takes place when pressure builds up in the working space by axial movement of the locking piston against the bias of the locking piston spring. By releasing the interlocking effecting interlocking Forced locking of the locking piston takes place at infinitessimal axial movement of the piston - mediated via axially inclined contact surfaces of the locking element to the recess in the cylinder - the complete impressions the locking elements in the annular space between the piston rod and cylinders.

For the realization of an end position lock at high pressures are not in line contact pressing balls but preferably in area contact pressing circle segments as Locking elements used. For the prevention of leakage The space will be disrupted by the bias for the locking piston via a locking piston spring takes place via a channel and a valve to the opposite Working space relaxed, preferably within the Piston rod. To ensure an optionally improved axial guidance of the piston in the cylinder alternate alternately axially leading parts of the locking element support with parts of the locking piston spring or locking piston springs from. By the preferably modular Structure of the construction parts required for locking with respect to the piston is an optional embodiment of the working cylinder easily possible with and without locking.

• der im wesentlichen gleichartigen Ausführung der an beiden Systemen für die Verriegelung benötigten Konstruktionsteile,
• der Möglichkeit einer - auch bezüglich der Verschlußkappen - relativ schlanken materialsparenden Bauausführung,
• der auch im höheren Druckbereich funktionssicheren Konstruktion
• der schonenden Behandlung des Zylinderinnenrohres infolge flächiger Belastung der Sperrschieber
• der Gewährleistung der Funktionsfähigkeit auch bei langer Verriegelungszeit und
• der zusätzlichen Verwendung von Stell- und Positionierungssystemen im Kolbenstangenbereich, da dieser durch das Verriegelungssystem nicht verwendet wird.

The advantages of the invention are in particular

• the substantially similar design of the structural parts required for locking on both systems,
• the possibility of a - also with regard to the caps - relatively slim material-saving construction,
• the reliable function even in the higher pressure range
• the gentle treatment of the cylinder inner tube as a result of surface loading of the locking slide
• Ensuring the functionality even with long locking time and
• the additional use of positioning and positioning systems in the piston rod area, as this is not used by the locking system.

Fig. 1 als Endlagenverriegelung in der Führungsseite eines Arbeitszylinders

(Fig. 2 als Schnitt von Fig. 1)

Fig. 3 als Endlagenverriegelung in der Bodenseite eines Differentialarbeitszylinders

näher erläutert.The invention will be described as an embodiment of hand

Fig. 1 as Endlagenverriegelung in the guide side of a working cylinder

(Fig. 2 as a section of Fig. 1)

Fig. 3 as Endlagenverriegelung in the bottom side of a differential working cylinder

explained in more detail.

According to FIG. 1 and FIG. 2, there is a hydraulic working cylinder from a piston 1 on a piston rod 2, which is guided within a cylinder 3. In the end positions the stroke becomes the position of the piston 1 in the cylinder 3 positively locked by means of locking elements 4. This Endlagenverriegelung needed in addition to the locking elements 4 a, advantageously via a locking piston spring 5 - preloaded locking piston 6 and a Locking element support 7, which the locking elements 4 leads in their radial movement and locked axially. The end position lock is together with the piston 1 completely within the annulus between piston rod. 2 and cylinder 3 integrated. The locking elements 4 engage in locking the end position in recesses 8 of Cylinder inner shell, which preferably in a closure piece 9 are introduced. The locking element carrier 7 is connected to the piston 1 and between this and the end position to be locked on the piston rod 2 arranged. He partially contributes to the axial guidance of the piston 1 in the cylinder 3 and includes in corresponding Clear one or more locking piston springs 5, which the compressive bias of the on the piston rod 2 axially movable locking piston 6 generates when the Locking piston 6 - by the pressure of the working fluid on its end-oriented surface - the piston 1 approaches. The locking piston 6 has on its outer jacket a chamfer 10, which the locking elements. 4 positively between the recesses 8 and the locking element carrier 7 locked when the end position of the piston 1 is reached by the approach of the piston 1 built-up to the end position bias a radial Displacement to the outside of the locking elements 4 in the Recess 8 forces. The contact surface forms the locking elements 4 with the recess 8 a slight axial slope 11 off. The locking elements 4 are advantageously designed as circular segments, which in the recesses 8 a surface pressure is achieved. Advantageous is the space of the locking piston spring 5 via a thin channel 12 with a valve 13 to each connected to other, pressure-free working space, as well with existing leakage always a relaxation of this space given is.

According to Fig. 3, a differential working piston all necessary for end position locking construction elements as shown in FIG. 1, with these advantageous each mirrored at the interface of the piston 1. The thus achievable modular design of Endlagenverriegelung allows one in the production of working cylinders simple functional equipment oriented to customer requirements this with largely uniform construction parts.

Used reference signs

1

piston

2

piston rod

3

cylinder

4

locking elements

5

Locking piston spring

6

locking piston

7

Locking element carrier

8th

recesses

9

closing piece

10

chamfer

11

slope

12

channel

13

Valve

Claims (6)

1. Hydraulic working cylinder having an end position locking arrangement, wherein a piston (1) is guided on a piston rod (2) within a cylinder (3) provided with closure pieces and in the end positions of the stroke the position of the piston (1) is positively locked in the cylinder (3) by way of locking elements (4), wherein the piston (1) and the locking elements (4), which are required for each modularly constructed end position locking arrangement, of the pretensioned locking piston (6) and of the locking element support (7) are completely integrated within the annular chamber between the piston rod (2) and the cylinder (3), and wherein the locking element support (7) is connected to the piston (1) and is disposed on the piston rod (2) between the piston and the end position which is to be locked, whereby the locking elements (4) are operatively connected to the piston (1) by way of the locking element support (7), characterised in that
   in the end position, for releasing the locking elements (4), at least in a first phase the pressure of a medium is initially provided in a pressure chamber which is formed by the closure piece (9), the piston rod (2) and the locking piston (6), wherein the locking piston (6) moves closer towards the piston (1).
2. Hydraulic working cylinder having an end position locking arrangement as claimed in claim 1, characterised in that
   an arrangement consisting of locking elements (4), the locking piston (6), the locking element support (7) within the annular chamber between the piston rod (2) and the cylinder (3) on the piston (1) is mirrored in the case of differential working cylinders.
3. Hydraulic working cylinder having an end position locking arrangement as claimed in claim 1 or claim 2, characterised in that
   the locking elements (4) provided are not spherical.
4. Hydraulic working cylinder having an end position locking arrangement as claimed in any one of claims 1 to 3, characterised in that
   the chamber of the locking piston spring (5) which serves to pretension the locking piston (6) is relieved of pressure by way of a duct (12) and a valve (13) leading to the opposite-lying working chamber.
5. Hydraulic working cylinder having an end position locking arrangement as claimed in any one of claims 1 to 4, characterised in that
   axially guiding parts of the locking element support (7) alternate with parts of the locking piston spring (5).
6. Hydraulic working cylinder having an end position locking arrangement as claimed in any one of claims 1 to 5, characterised in that the modular structure of the structural parts, which are required for locking purposes, in relation to the piston (1) makes it readily possible to produce the working cylinder as required with or without a locking arrangement.

Images