EP1420171A2 - Hydraulic working cylinder - Google Patents

Abstract

Hydraulic working cylinder has a connecting part (14) formed as a locking piston (20) which axially moves wit a pressure spring (16) on a support part (19) of a threaded spindle (11). A toothed profile (21) which interacts with a counter toothed arrangement (22) is provided on the front side of the locking piston directed toward the end of the cylinder base and is supported in a pushing body (17). Preferred Features: The locking piston and the pushing body having an adjusting drive (24) form a permanent connecting unit in the unlocked position in the region of a support bearing (23). The locking piston is connected to the outer ring (25) of the support bearing. The locking piston has a sliding bearing as a central support bearing.

Description

The invention relates to a hydraulic working cylinder, in particular a plunger cylinder, according to the preamble of claim 1, wherein this in the cylinder bottom with a locking unit braking the movement of the piston rod is provided.

With a hydraulic working cylinder of this type (DE 200 11 789.0) points this on a sleeve-shaped piston rod, which starts from the area of their front working piston is penetrated by a threaded spindle. With this The threaded spindle acts in the area of the working piston Spindle nut together so that the working piston has a linear thrust movement can execute and at the same time the threaded spindle rotates freely in the cylinder base is held. For braking or interrupting the thrust movement, for example for security purposes when extended, can the threaded spindle by means of an axially displaceable connecting member and a non-rotatable counter member of a locking unit in the area of the cylinder bottom. The component arrangement provided has an axially movable locking disk as a connecting member, wherein their control by several arranged at a distance from the central longitudinal axis Tappet is complex and several for frontal support in the cylinder bottom rotatable threaded spindle sleeve parts are provided with a Variety of control bores and sealing surfaces provided, so that this locking unit is particularly susceptible to faults with high technical effort.

The invention addresses the problem of a hydraulic cylinder with an internal locking unit that can be manufactured with little and assembly effort even under harsh operating conditions Functionally reliable, finely graduated and reliably lockable component arrangement forms and their sealing arrangement requires little maintenance and enables an extended operating time of the working cylinder.

Starting from a hydraulic cylinder according to the generic term of Claim 1, the invention solves this problem with the features of the characterizing Part of claim 1. With regard to essential further refinements reference is made to claims 2 to 19.

The working cylinder according to the invention has in the area of its cylinder bottom a locking piston provided as a link, which as a functional Unit with a tooth profile provided on the end face of this and a support bearing provided in its area cooperates. In the movement position of the working piston is the threaded spindle in the one with working pressure loadable interior of the cylinder base without additional rotary seals optimally supported load, this from the pressure medium Surrounded support is retained even if the front locking unit the locking piston by means of the compression spring engaging behind it is shifted into the locking position.

To release the toothing profiles from the locked position, a axial displacement of the locking piston over a thrust body with an end Bearing, the displacement pressure transferred to the locking piston, the Gearing disengaged and thereby the free rotation of the Threaded spindle is possible.

This comparatively simple support of the locking piston by a bearing Connection to the thrust body enables a positionally accurate external Activation of the locking function in the field of gear profiling done particularly finely. This means that when the locking function is activated compression of the extended piston rod also under swelling loads can be avoided. The lock function is too effective if there is a leak in the hydraulic system, for example due to hose breakage, which would be feared to sink under load. In this Situation, the thrust body is depressurized and by axial displacement of the locking piston engage in particular formed by a Hirth toothing Profiles in one another. The insertion load of the piston rod is now through the Braking effect in the area of the connection, which has only slight self-locking picked up by the threaded spindle and spindle nut and on the locking assembly transferred so that the generated on the threaded spindle Torque is blocked.

The hydraulic working cylinder can by the interlocking of the locking unit in fine steps in small steps, for example after a stroke of 0.2 mm, can be fixed in the position reached in each case. The simple structure of the system with the locking piston enables within the working pressure space a query of the locking function via a sensor on the cylinder housing.

Furthermore, the rotational position of the Threaded spindle are detected, so that it is a position measuring system for the cylinder stroke is reached.

The stability of the locking unit in the area of the teeth enables the use of a multi-start Trapetz thread in the area of the spindle nut and the lead screw, so that these parts have a high pitch and low May have self-locking. This area of the working cylinder and the assembly of the locking device is permanently flushed with hydraulic oil, so that there is little wear in these areas. With this locking system is the working cylinder especially for operating conditions in scissor lift tables and other lifting and transport units designed, whereby the System compared to electromechanical drives through the simple controllable hydraulic drive and its flexibly adaptable to the operating conditions Design offers special advantages.

The working cylinder enables problem-free starting even under load stand, has a compact design with only small installation dimensions on and is with little effort to different operating conditions adaptable. Also an exchange of commercially available hydraulic cylinders for the Working cylinder according to the invention can be implemented with little effort. to Realization of an emergency drain function can the cylinder in the area of The pressure medium connection on the thrust body is easily unlocked by a hand pump become.

Fig. 1

eine Schnittdarstellung des erfindungsgemäßen Arbeitszylinders mit in Freigabestellung verlagerter Verriegelungseinheit im Bereich des Zylinderbodens,

Fig. 2

eine Schnittdarstellung ähnlich Fig. 1 mit der Verriegelungseinheit in Verriegelungsstellung,

Fig. 3

eine vergrößerte Ausschnittsdarstellung des Arbeitszylinders gemäß Fig. 2 im Bereich des Zylinderbodens,

Fig. 4

eine vergrößerte Ausschnittsdarstellung ähnlich Fig. 3 mit der Verriegelungseinheit in Freigabestellung,

Fig. 5

eine Darstellung ähnlich Fig. 4 mit einer Abstützung des Rastkolbens mittels einer Keilwellenprofilierung und eines Wälzlagers ähnlich Fig. 1,

Fig. 6

eine zweite Ausführung des Rastkolbens mit einer veränderten Verriegelungs-Verzahnung,

Fig. 7

eine Darstellung ähnlich Fig. 6 mit dem Rastkolben in Verriegelungsstellung, und

Fig. 8

eine Darstellung ähnlich Fig. 3 mit einer eine reibschlüssige Bremse aufweisenden Verriegelungseinheit.

Further details and advantageous configurations result from the following description and the drawings, which illustrate several exemplary embodiments of the hydraulic working cylinders with an internal locking unit. The drawings show:

Fig. 1

2 shows a sectional view of the working cylinder according to the invention with the locking unit displaced in the release position in the region of the cylinder base,

Fig. 2

2 shows a sectional illustration similar to FIG. 1 with the locking unit in the locking position,

Fig. 3

2 shows an enlarged detail of the working cylinder according to FIG. 2 in the region of the cylinder bottom,

Fig. 4

3 with the locking unit in the release position,

Fig. 5

4 with a support of the locking piston by means of a spline and a roller bearing similar to FIG. 1,

Fig. 6

a second embodiment of the locking piston with a modified locking toothing,

Fig. 7

a view similar to FIG. 6 with the locking piston in the locking position, and

Fig. 8

a representation similar to FIG. 3 with a locking unit having a friction brake.

In Fig. 1 is a hydraulic cylinder generally designated 1 in Shown a plunger cylinder, the one in a cylinder housing 2 between a cylinder base 3 and a cylinder head 4 displaceable piston rod 5 (arrow K ', Fig. 1). This in an interior 6 of the cylinder housing 2 displaceable piston rod 5 is in turn sleeve-shaped and has in its interior 7 in the area of the annular working piston 8 entering threaded spindle 11 by means of a trapezoid thread 10 in the area of a threaded connection effective in the manner of a spindle nut 9 is rotatably supported.

The threaded spindle is in its longitudinal extension towards the area of the cylinder base 3 11 supported by a bearing assembly, generally designated 12, in the area of which stop the rotary movement according to arrow direction A. Locking unit 13 is provided. This locking unit has an axially slidably connected to the threaded spindle 11 connecting member 14 on that in the area of a rotationally fixed at the front end in the interior E of the cylinder bottom 3 held counter member 15 can be braked. In connection with such a locking unit 13 is also known that the connecting member 14 by means of a compression spring 16 in the connecting position (Fig. 2) relocatable (arrow F) and the connecting member 14 through a pushing body 17 displaceable against the spring action can be unlocked is (arrow S).

In Fig. 3 is an enlarged schematic diagram of the structure according to the invention the locking unit 13 similar to FIG. 2 shown. It becomes clear that the connecting member 14 as a with the compression spring 16 on a support attachment part 19 of the threaded spindle 11 formed axially displaceable locking piston 20 is. This locking piston 20 is at the front end of the cylinder bottom 3 facing end face provided with a toothing profile 21, which can be snapped into counter-teeth 22 on the bottom (FIG. 4).

This toothing profiles 21, 22 form with a coaxial to this Locking piston 20 centrally receiving support bearing 23 and interacting with it Thrust body 17 is a functional unit with which one in almost Infinitely accessible stroke positions of the working piston 8 switchable Locking is possible, which is simple and reliable Component design. The locking piston 20 and one on the back Actuator 24 having thrust bodies 17 form in the region of the support bearing 23 a connection unit, such that the slidable on the support extension part 19 Locking piston 20 by means of the support bearing 23 in the exact position Counter toothing 22 can be locked and disengaged.

In the illustrated embodiments according to FIGS. 1, 2, 5 and 7, the locking piston 20 each with an outer ring 25 of a roller bearing Support bearing 23 connected and this detects with its inner ring 26 the Thrust body 17. It is also conceivable that the locking piston 20 as the central Support bearing 23 cooperates with a plain bearing (not shown).

With the support of the threaded spindle 11 via the front bearing assembly 12 in the area of the working pressure chamber E and the locking unit is low Effortlessly simple and effective load handling possible that in the unlocked state of the piston rod 5 when entering and Extend a largely friction-free rotary movement (arrow A) of the threaded spindle 11 allows and in the locking position (Fig. 5) an optimal Power transmission and only minimal play guaranteed. In the locked state changing loads on the hydraulic cylinder 1 are problem-free recordable and also this cylinder has low maintenance a long service life.

The basic representations according to FIGS. 3 and 4 clarify when viewed together the different working positions of the locking piston 20, it being clear that in the construction according to the invention, the shoulder part 19 with its front bearing assembly 12, which is engaged by the compression spring 16 Locking piston 20 with the support bearing 23 and the end face of the cylinder bottom 3 penetrating thrust piston 17 with its receiving the support bearing 23 Holding part 27 in the common working pressure space E with the front Extend working piston 8. A spindle lock is thus achieved at that of the shoulder part 19 in all of its support and connection areas is held without rotary seals so that the hydraulic connection 29 (working pressure: arrow K) total pressure area of the construction is less prone to failure and optimal long-term tightness even under high loads having.

In the representations of the hydraulic cylinder 1 according to FIGS. 1 to 5, the locking piston is 20 in the area of the locking unit 13 with two opposite one another an unlockable connection in the manner of a Hirth serration and in the sectional view, only in principle visible ring gears 30, 31 (Fig. 4) provided, which can be applied to the locking piston 20 during unlocking Thrust body 17 is guided centrally into the working pressure chamber 28. In the embodiment 6 and 7, the locking piston 20 'has a toothing profile a helical spur gear profile 32, which in the internal gear 33 can be inserted into the cylinder base 3 (connection position: FIG. 7). 6 shows the schematic representation of this locking assembly 13 'a recessed receiving contour 28 'into the support bearing 23 corresponding to the contour 28 in FIG. 3 immersed in the blocking position of the profiles 32 and 33.

The interacting with the locking piston 20, 20 'thrust body 17 has in Area of the through bore D provided in the cylinder base 3 Sealing ring 34 'and a guide ring 34, which is a central guide part 35 of the thrust body 17 embrace. At the same time, the thrust body 17 is included a pressure piston 36 is received in an outer pressure chamber 37, so that the thrust body 17 by means of the pressure piston 36 on the outside with a control pressure (Pressure port 38) can be acted upon and thus the actuator 24 is effective becomes.

The construction of the locking unit 13 is in the area of the thrust body 17 3, 4 and 6 shown with one-piece cylinder base 3. In several parts Execution (Fig. 1, 2 and 7) is the working pressure chamber 28 with one of the thrust body 17 penetrated in the area of the through hole D, front Locking sleeve 39 is closed, the radially expanded and outside has a pressure chamber 37 closed by a cover part 40. In the the pressure chamber 37 can be pressurized with fluid pressure (arrow P) formed in particular in one piece with the thrust body 17, also one Execution with screwed individual parts is conceivable (not shown).

For the control of the locking unit by means of the thrust body 17 points this has a diameter B in the region of the pressure piston 36 which is larger than the diameter C in the area of the middle guide part 35 (FIG. 3).

This is a particularly effective control in the area of the locking piston 20, 20 'reached because with a comparatively low pressure P in the range of Pressure piston 36 a corresponding to the ratio of the areas of B: C Pressure translation of the available pressure force (arrow S) for the area of the Support bearing 23 is reached. This serves the purpose of the required hydraulic Pressure to control the locking function in a similar Order of magnitude to keep the pressure of the piston rod 5. simultaneously is the transmission of interference from the working hydraulics in the pressure chamber E minimized to the control in the pressure chamber 37.

The seals 41 and 34 'in the area of the thrust body 17 are in the Adjustment movements of the thrust body 17 are only slightly loaded because of the switching paths are short and no rotary seals are used. The thrust body 17 acts in the area of the pressure piston 36 with a front at 37 'in the Pressure space 37 opening vent hole 42 together (Fig. 3). in the The area of its pressure piston 36 has a thrust body 17 at a distance R to the central longitudinal plane M extending retaining pin 49 on the one hand in the cover part 40 is held and on the other hand axially displaceable in a bore 50 of the Pressure piston 36 engages. This prevents the thrust body 17 from rotating.

In an expedient embodiment, the locking piston 20 is on the support attachment part 19 held by a spline 43 so that an optimal axial displacement in the direction of the central longitudinal axis M is possible. At the same time, this can Profiling the respective torques effective in the locking position optimal take up. Instead of the spline 43, the application is also a tongue and groove connection 44 (FIG. 1) is conceivable.

For the optimal control of the hydraulic cylinder 1 it is provided that the Locking piston 20, 20 'with a position sensor which detects its range of motion 45 interacts. The position sensor 45 is in the Cylinder base 3 engaging transducer 45 'provided by a close this displaceable contour formation 46 and an annular recess 46 'on the locking piston 20 whose respective position and thus the switching position of the lock is detected. It is also conceivable that the threaded spindle 11 with its angular position detecting sensor (not shown) cooperates so that a Distance measurement of the respective stroke position of the piston rod 5 is possible.

For the embodiment of the locking unit 13 according to the invention, the supporting attachment part is 19 in the area of its in front of the engaging pistons 20, 20 ' Compression spring 16 with two thrust bearings 47, 48 (Fig. 1, 2, 5 and 7) in the working pressure chamber E of the cylinder base 3 is supported so that the locking structure overall, a largely axial play-free and smooth construction is guaranteed.

The locking described above in the area of the locking piston 20, 20 'is as axially switchable unit can be used with a fine level. During a shift are 5 respective lifting heights on the extending or retracting piston rod less than 0.5 mm realizable and after reaching the respective Position, stable locking and locking is possible. Here is the front Tooth profile 30, 31; 32, 33 in particular with oblique flanks trained so that the switchability of the system is improved and a Automatic self-centering, especially with the shepherd's teeth, which are known per se is achieved.

This construction of the hydraulic cylinder 1 is particularly in lifting devices can be used as a securing and / or holding device, so that, for example for a failure of the device during operation of the device Drive hydraulics a reliable backup is guaranteed or approached Stroke positions can be held securely. With the constructive design of the thrust body provided with the pressure reinforcement in area B to C. 17 can avoid interference from the working hydraulics and overall the security of the system can be improved, this in the area of guided by the front bearing assembly 12 and the support bearing 23 Locking piston 20 has a long-term stable locking function.

8 shows a further embodiment of the working cylinder 1 ', whose construction corresponds essentially to that in Fig. 3, so that the corresponding reference numerals of the individual parts even without repeated Result in registration. The hydraulic cylinder 1 'is with a locking unit 13 'provided, which in place of the toothing profiles 21, 22 (Fig. 3) in the area of a locking piston 20 "with a friction brake 51st is provided, the friction element (s) are shown in a braking position and thus ensure the locking function described above.

Claims (19)

Hydraulic working cylinder, in particular a plunger cylinder, with a sleeve-shaped piston rod (5) which can be displaced in a cylinder housing (2) between a cylinder base (3) and a cylinder head (4) by fluid pressure (K), the working piston (8) of which is displaced by a linear thrust movement ( K ') is penetrated in the area of a spindle nut (9) rotatable threaded spindle (11) which is supported in the longitudinal direction towards the area of the cylinder base (3) by at least one bearing assembly (12), in the area of which a rotary movement (A) of the threaded spindle (11) by means of an axially displaceable connecting member (14) and a non-rotatable counter-member (15) braking locking unit (13) is provided, the connecting member (14) held in the connecting position by means of a compression spring (16) being displaceable by an anti-spring effect (F) Push element (17) can be unlocked, characterized in that the connecting member (14) as one with the compression spring (16) a supporting attachment part (19) of the threaded spindle (11) axially displaceable locking piston (20; 20 ') is formed, on the front end of which is directed towards the front end of the cylinder base (3), a toothed profile (21) which runs in the form of a ring and can be latched on a counter-toothing (22) on the bottom, and coaxially with the locking piston which can be displaced on the support attachment part (19) (20; 20 ') is rotatably supported on the thrust body (17) by means of a central support bearing (23). Hydraulic working cylinder according to claim 1, characterized in that the detent piston (20; 20 ') and the thrust body (17) having a rear actuator (24) form a permanent connecting unit in the unlocked state in the region of the support bearing (23). Hydraulic working cylinder according to claim 1 or 2, characterized in that the locking piston (20, 20 ') is connected to the outer ring (25) of a support bearing (23) designed as a roller bearing and this grips the thrust body (17) with its inner ring (26) , Hydraulic working cylinder according to claim 1 or 2, characterized in that the locking piston (20; 20 ') has a slide bearing as the central support bearing. Hydraulic working cylinder according to one of claims 1 to 4, characterized in that the support attachment part (19) with its front bearing assembly (12), the locking piston (20; 20 ') which is engaged by the compression spring (16) with the support bearing (23) and the thrust piston (17) penetrating centrally through the cylinder base (3) with its holding part (27) receiving the support bearing (23) extends in a common working pressure chamber (E) into which a hydraulic connection (29) opens. Hydraulic working cylinder according to one of claims 1 to 5, characterized in that both the supporting attachment part (19) of the threaded spindle (11) in the region of the working pressure space (E) and the locking unit (13) are each supported without rotary seals. Hydraulic working cylinder according to one of claims 1 to 6, characterized in that the locking piston (20) is provided as a toothing profile (21, 22) with two toothed rings (30, 31) forming the unlockable locking connection opposite one another in the manner of a Hirth toothing Inner circle of the thrust body (17) which can be placed on the locking piston (20) at least during the unlocking is guided centrally into the working pressure chamber (E). Hydraulic working cylinder according to one of claims 1 to 7, characterized in that the axially displaceable thrust body (17) has a sealing ring (34 ') and a guide ring (34) in the region of the axial through-bore (D), which has a central guide part (35) of the thrust body (17). Hydraulic working cylinder according to one of claims 1 to 8, characterized in that the thrust body (17) with a pressure piston (36) is received in a pressure chamber (37), so that the pressure piston (36) can be acted upon on the outside with a control pressure (P) , Hydraulic working cylinder according to one of claims 1 to 9, characterized in that the working pressure chamber (E) is closed by a locking sleeve (39) which is penetrated by the thrust body (17) in the region of the through bore (D) and which extends the radially enlarged and outside has a cover part (40) closed pressure chamber (37), in which the pressure piston (36), which is integrally connected to the thrust body (17), can be acted upon on the outside with fluid pressure (P). Hydraulic working cylinder according to claim 9 or 10, characterized in that the thrust body (17) in the region of the pressure piston (36) has a larger diameter (D) than the central guide part (35, diameter C) or the front holding part (27, diameter) C '). Hydraulic working cylinder according to one of claims 1 to 11, characterized in that the thrust body (17) in the region of its pressure piston (36) engages with a distance from the central longitudinal plane (M) of the cylinder (1) and engages axially displaceably in the pressure piston (36) Has retaining pin (49) which is on the other hand held in the cover part (40). Hydraulic working cylinder according to one of claims 1 to 12, characterized in that the thrust body (17) in the area of the pressure piston (36) interacts with a vent hole (42) opening into the pressure chamber (37) at 37 '. Hydraulic working cylinder according to one of claims 1 to 13, characterized in that the locking piston (20; 20 ') on the support attachment part (19) is fixed axially displaceably by means of a spline profile (43), a feather key connection (44) or the like. Hydraulic working cylinder according to one of claims 1 to 14, characterized in that the latching piston (20 ') has a straight toothed spur gear profile (32) as toothing profile which can be inserted into a straight toothed inner profile (33) in the cylinder base (3). Hydraulic working cylinder according to one of claims 1 to 15, characterized in that the detent piston (20; 20 ') interacts with a position sensor (45) which detects its range of movement. Hydraulic working cylinder according to one of claims 1 to 16, characterized in that the supporting attachment part (19) in the area in front of the compression spring (16) engaging behind the locking piston (20; 20 ') with a bearing assembly (axial roller bearings 47, 48) in the working pressure chamber ( E) the cylinder base (3) is supported. Hydraulic working cylinder according to one of claims 1 to 17, characterized in that the threaded spindle (11) interacts with a sensor which detects its angular position and with which a position measuring system for the stroke position of the piston rod (5) is connected. Hydraulic working cylinder with a locking unit according to one or more of Claims 1 to 18, characterized in that the locking unit (13 ') is provided with a frictional brake (51) in the region of its displaceable piston (20 ").

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