DE19758159C2 - Linear drive with integrated pneumohydraulic pressure intensifier - Google Patents

Description

The invention relates to a linear actuator with integrated pneumohydraulic pressure transducer. Such units are preferably used for the following requirements:

• - Highly dynamic driving through a variable distance with relatively little Resistance to movement (rapid stroke phase),
• - Automatic power build-up at any point of the rapid stroke when it hits ten of a relatively large movement resistance compared to the rapid stroke phase (Power stroke phase).

Such requirements lie, for example, in the most varied Tasks ahead. The tool is first approached to the workpiece in a rapid stroke and automatically when placed on the workpiece for a further distance, the so-called power stroke, with relatively large force.

The state of the art is shown in the publications of the following representative companies:
Tox-Pressotechnik GmbH, Weingarten; Schmidt Feintechnik GmbH, St. Georgen and Farger & Joosten Maschinenbau GmbH, Hohentengen.

The company-specific units differ only by a few minor details and essentially consist of 4 functional areas connected in series:

• - pressure booster piston with coupled plunger,
• - fluid accumulator with pneumatically or spring-loaded accumulator pistons,
• - high pressure chamber fixed to the frame,
• - Double-acting working cylinder with coupled high-pressure pistons.

The rapid stroke is switched on for all units via a pneumatic valve Pressurizing the double-acting cylinder. When the working col bens, due to a correspondingly large movement resistance, the booster piston automatically pressurized via a further pressure-controlled pneumatic valve, the coupled plunger is the hydraulic connection between the fluid reservoir and High pressure chamber interrupts. A translation is created in the high pressure chamber of the primary pressure corresponding to the diameter ratio of the pressure intensifier piston and plunger, whereby pressures of up to 400 bar at the high-pressure piston are effective can.

Due to the system-related large number of parts of the aggregates presented on the market, there are the following significant disadvantages:

• - Relatively high manufacturing costs caused by the considerable manufacturing and Assembly effort,
• - increased probability of failure corresponding to the relatively large number moving parts, sealing elements and joints.

The invention has for its object a compact linear drive with integrated to develop pneumohydraulic pressure intensifiers with a considerably reduced number of parts, fewer sealing elements, joints and moving parts and fewer pneumotechni circuit effort.

This object is achieved by the features of patent claim 1. The high trained as a pipe The axial pressure chamber is freely movable and forms a pressure over with the pneumatically driven pressure setter piston one unit. The pressure booster piston is supported by a cylinder tube two cylinder covers and can be pressurized on both sides. Of the High-pressure piston is arranged inside the high-pressure chamber and in certain Limits can be moved freely relative to this. The piston rod of the high pressure piston is via a system of seals and guides, both in the high pressure chamber or Pressure intensifier piston as well as in the cylinder cover, led out of the cylinder.  

Unlike the above conventional aggregates will function as the working piston taken from the pressure booster piston or accumulator piston. During the rapid stroke phase is the high pressure piston via an impressed overpressure in the high pressure chamber to an annular stop surface at one end of the high pressure chamber or the translator piston pressed. As a result, there is no relay in this phase active movement between the two systems. The other end of the high pressure chamber will sealed by a plunger fixed to the frame, the outside diameter of which depends Desired pressure ratio is correspondingly smaller than the inside diameter of the High pressure chamber or the outside diameter of the high pressure piston. This ring area corresponds to the cross-sectional area of the plunger of the embodiment described above state of the art. With an infinitesimally small difference in diameter theoretically a pressure translation in the direction of infinite is conceivable. To such high Druckbe To reach rich would have to be an infinitesimally small plunger with the conventional solution diameter can be selected, but this is not possible for technical reasons leaves.

The supply of hydraulic fluid to compensate for leaks and changes in volume the high-pressure chamber in the case of rapid stroke back and forth is via a hydraulic coupling th fluid reservoir with overpressure. During these phases, the pressure transfer meter dium via connecting channels from the storage to the high pressure chamber or vice versa Drain pressure so that cavitation is avoided.

There are the following basic options for arranging the memory:

• - fixed coupling to the booster piston or high pressure chamber,
• - fixed coupling,
• - Combination of both options.

If there is a relatively large resistance to movement on the piston during the rapid stroke phase rod of the high pressure piston, then this remains relative to the high pressure moving on chamber back, whereby the connection to the storage is hydraulically separated. This ge happens by running over the connecting channels of the high pressure chamber and the accumulator through the high pressure piston or alternatively via a hydraulic valve. Which in this case The high pressure building up in the high pressure chamber is supported by the high pressure piston tion on the face of the aforementioned stationary plunger effective.  

By simply switching the pneumatic valve, the booster piston and thus also the coupled high pressure chamber retracted, whereby the high pressure piston again shifts relative to the high pressure chamber and the connecting channels to the Spei cher releases, so that a pressure reduction to the pressure level of the memory is made possible. The high-pressure piston takes its original stop position in the pressure ratio piston or high-pressure chamber back in and moves to the starting position return

Further details and features of the invention are apparent from the following description of Embodiments can be seen with reference to the drawing. Show it:

Fig. 1 is a schematic representation of the individual components of a first embodiment of the present invention exporting approximately linear drive with integrated pneumohydrauli rule pressure intensifier, and entrained fluid reservoir with a filling made of a highly compressible, resiliently deformable material,

Fig. 2 is a schematic representation of the individual components moved along a second exporting approximately embodiment of the invention the linear drive with integrated pneumohydrauli rule pressure intensifier and, spring-biased fluid reservoir,

Fig. 3 is a schematic representation of the individual components of a third embodiment of the present invention exporting approximately linear drive with integrated pneumohydrauli rule pressure intensifier, frame-fixed fluid storage and rigid connection channels to the high pressure chamber,

Fig. 4 is a schematic representation of the individual components of a fourth embodiment of the present invention exporting approximately linear drive with integrated pneumohydrauli rule pressure intensifier, frame-fixed fluid storage and resilient coiled Verbin extension tube to the high pressure chamber,

Fig. 5 is a schematic representation of the individual components of a fifth embodiment example of the invention approximately linear drive with integrated pneumohydrauli rule pressure intensifier and fixed to the frame, elastic fluid reservoir,

Fig. 6 is a schematic representation of the individual components of piston of a sixth example of the present invention exporting approximately linear drive with integrated pneumohydrauli rule pressure intensifier frame-fixed fluid storage and led out pressure intensifier,

Fig. 7 is a schematic representation of the individual components of a seventh embodiment of the present invention exporting approximately linear drive with integrated pressure intensifier pneumohydrauli rule, fixed to the frame memory, and hydraulic support fluid of high pressure directly on the cylinder cover,

Fig. 8 is a schematic representation of the individual components of an eighth embodiment of the present invention exporting approximately linear drive with integrated pneumohydrauli rule pressure intensifier, entrained fluid storage and a compensation means for wegunabhängigen constant the volumes of fluid in high pressure chamber and Fluidspei cher,

Fig. 9 is a schematic representation of the individual components of a ninth exemplary embodiment of the linear drive with integrated pneumohydraulic pressure intensifier, frame-mounted pressure accumulator and integrated control valve for the hydraulic connection or separation of the high pressure chamber and fluid accumulator.

Fig. 10 is a schematic representation of the individual components of a tenth exemplary embodiment of the linear drive with integrated pneumohydraulic pressure intensifier, frame-fixed fluid reservoir, hydraulic connection of high-pressure chamber and fluid reservoir and a device for stroke displacement (variant 1).

Fig. 11 is a schematic representation of the individual components of an eleventh exemplary embodiment of the linear drive with integrated pneumohydraulic pressure intensifier, frame-fixed fluid reservoir, hydraulic connection of high-pressure chamber and fluid reservoir, and a device for stroke displacement (variant 2).

Fig. 12 is a schematic representation of the individual components of a twelfth exemplary embodiment of the linear drive with integrated pneumohydraulic pressure intensifier, frame-fixed fluid reservoir, hydraulic connection of high-pressure chamber and fluid reservoir and a device for stroke displacement (variant 3).

Fig. 13 is a schematic representation of the individual components of a thirteenth exemplary embodiment of the linear drive with integrated pneumohydraulic Drucküberset zer, frame-fixed fluid reservoir, hydraulic connection of high pressure chamber and fluid reservoir and a device for stroke displacement and path-dependent power stroke engagement (variant 4).

Fig. 14 is a schematic representation of the individual components of a fourteenth exemplary embodiment of the linear drive with integrated pneumohydraulic Drucküberset zer, frame-fixed fluid reservoir, hydraulic connection of high pressure chamber and fluid reservoir and a device for stroke displacement and path-dependent power stroke engagement (variant 5).

The linear drive according to FIG. 1 consists of the following significant components:

High-pressure piston 1 with 1 a high pressure seal and the piston rod 1b. Pressure booster piston 2 , high pressure chamber 3 , return piston 4 , fluid reservoir 5 , plunger 6 , cylinder flanges 7 and 8 , cylinder tube 9 , tie rods 10 and the pneumatic valve 11 .

Pressure intensifier piston 2 , high pressure chamber 3 , return piston 4 and fluid accumulator 5 form one unit. The entire assembly is held by pressurizing the return stroke piston 4 via the pneumatic valve 11 in the right end position.

In both stroke end positions, the kinetic energy of the moving mass is absorbed by end positions, the cylindrical end regions 4 a and 3 c plunging into the damping chambers 7 a and 8 a. In the applications where the start position of the power stroke is constant, the kinetic energy of the moving masses to be efficiently absorbed, it is advantageous for the damping chamber 7 a, axially relative to the forming cylinder flange 7 adjustable.

The high pressure chamber 3 is sealed on the left side by the high pressure piston 1 and on the right side by the plunger 6 fixed to the frame. Immediately on the high-pressure piston 1 to close, is in the high-pressure chamber, the double-conical groove 3 a with the connecting channels 3 b to the fluid reservoir 5th

On the one hand, the fluid reservoir 5 has the function of compensating geometrically caused changes in volume of the volume of the high-pressure chamber and, on the other hand, to compensate for any leaks that occur. In order to keep the moving mass as small as possible, the storage jacket 5 a is formed as a cylindrical, thin-walled tube. To ensure a quasi-static preload, the storage jacket is made with a highly compressible elastic material 5 b, z. B. chloroprene rubber filled with nitrogen-filled pores. The desired prestressing pressure can be achieved by appropriately dimensioned fluid filling of the high pressure chamber 3 and fluid reservoir 5 .

As a result of the impressed overpressure of the high pressure piston 1 to the annular An is striking surface in Rückhubkolben 4 is pressed and is moved "back" upon pressurization of the pressure booster piston 2 in the direction "before" or upon pressurization of the return stroke of piston 4 in direction. The empty space between storage jacket 5 a, Zy relieving pipe 9 and pressure intensifier piston 2 and Rückhubkolben 4, can be advantageously 3 e for venting the air-fluid separation and 4 b in the pressure booster piston 2 and the return stroke piston 4 use. The empty space is vented through the through hole 9 a in the cylinder tube 9 .

If the piston rod 1b of the high-pressure piston 1 at any point of Eilhubes "before" by a relatively large resistance to movement of the further process is prevented, there is a relative displacement to the high pressure chamber. 3 Here, the hydraulic connection to the fluid reservoir 5 is interrupted when passing over the connecting channels 3 b of the high pressure chamber 3 through the high pressure seal 1 a of the high pressure piston 1 , and there is an increase in pressure in the high pressure chamber 3 . The pressure ratio of the primary pressure is dependent on the annular surface 3 d corresponding to the difference in diameter of high-pressure piston 1 and plunger 6 , and the difference in diameter of pressure booster piston 2 and plunger 6 .

The approach stroke is "back" initiated by switching the pneumatic valve 11, wherein the Rückhubkolben 4 is pressurized and the Hochdruckolben 1 channel 3, the connection b to the fluid reservoir 5 releases it again. The entire movable assembly moves to the right end position.

The second exemplary embodiment shown in FIG. 2 essentially corresponds to the exemplary embodiment according to FIG. 1, but the following changes have been made;

• - Replacement of the rigid storage jacket 5 a and the compressible filling 5 b by the corrugated metal corrugated hose 5 c in the axial direction,
• - Axially movable arrangement of the pressure booster piston 2 relative to the high pressure chamber 3 and preload on the compression spring 2 c.

The prestressing of the hydraulic pressure transmission medium is effectively supported by the pressurization of the pressure booster piston 2 during the rapid stroke “before”.

The third exemplary embodiment shown in FIG. 3 likewise corresponds in essential points to the exemplary embodiment according to FIG. 1, but instead of the moving fluid reservoir, a fluid reservoir 5 fixed to the frame, designed as a bladder reservoir, is provided. The return piston 4 also takes on the function of the pressure booster piston 2 according to FIG. 1 in the present case . The hydraulic connection to the high pressure piston 1 takes place via connecting channels 3 f in the wall of the high pressure chamber 3 . Instead of the relatively expensive end position damping 3 c according to FIG. 1, the elastic damping disc 4 c is provided in the present embodiment.

The air-fluid separation 4 b is vented via the coiled hose 4 d to the cylinder flange 7 .

The fourth exemplary embodiment shown in FIG. 4 corresponds in essential points to the exemplary embodiment according to FIG. 3, but the hydraulic connection between the fluid reservoir 5 fixed to the frame and the high-pressure chamber 3 is produced by the coiled pressure hose 4 e. The air-fluid separations 4 b and 3 e are vented via the likewise coiled hose 4 d.

The fifth exemplary embodiment shown in FIG. 5 essentially corresponds to the exemplary embodiment according to FIG. 3, but instead of the fluid accumulator 5 designed as a bladder accumulator, the tire-shaped rubber compensator 5 d is provided. This design has the following advantages:

• - relatively large storage volume,
• - compact design,
• - Simple monitoring of the minimum storage volume possible.

Also in this embodiment, the bias pressure in the fluid reservoir 5 and high pressure chamber 3 , analogous to the fluid reservoir 5 shown in FIG. 1, by elastic expansion of the rubber compensator 5 d, adjusted via a corresponding fluid filling.

The sixth exemplary embodiment shown in FIG. 6 essentially corresponds to the exemplary embodiment according to FIG. 4, but the connecting tube 4 f is firmly coupled to the return piston 4 . The connecting pipe 4 f is led out of the cylinder flange 7 and thus represents an interface to the return piston 4. At this interface, for example in the case of a stamping application, the spring-loaded hold-down device of the stamping tool can be coupled. Furthermore, the connecting tube 4 f, the otherwise required air-fluid separation 4 b, saves on the piston rod of the high-pressure piston 1 .

In this exemplary embodiment, the return piston 4 also takes over the function of the pressure booster piston 2 according to FIG. 1.

The seventh embodiment shown in FIG. 7 corresponds essentially to the exemplary embodiment according to FIG. 3, but the plunger 6 fixed to the frame has been eliminated by a special design of the pressure booster chamber 3 . The Druckübersetzerkam mer 3 has been extended in the present case by the tubular extension 3 g. The pressure ratio results from the difference in diameter of the high-pressure piston 1 and the outer diameter of the tubular extension 3 g. The high pressure is supported directly on the right cylinder flange 8 .

The present design has the particular advantage that in a series with constant power stroke but different stroke lengths, the high-pressure chamber 3 only has to be combined with appropriately varied, tubular attachment parts 3 g.

The eighth exemplary embodiment shown in FIG. 8 essentially corresponds to the exemplary embodiment according to FIG. 2, the rubber compensator 5 e being used as an alternative to the corrugated metal hose 5 c. The geometrically related volume changes in the high-pressure chamber 3 will Fig invention. B balanced 8 by the fixed on the cylinder flange 7 coupled tubular compensating piston 7, so that the fluid accumulator 5 has to compensate only leakage losses and can be of its storage capacity dimensioned forth correspondingly smaller.

The ninth exemplary embodiment shown in FIG. 9 essentially corresponds to the exemplary embodiment according to FIG. 3, but the double-conical groove 3 a in the high-pressure chamber including the associated connecting channels 3 b to the fluid reservoir 5 are omitted. The control of the interaction of the high pressure piston 1 and the return piston 4 on the one hand and the high pressure chamber 3 and the fluid reservoir 5 on the other hand has been realized in the vorlie case by a valve combination. The to the pneumatic valve 11 is electrically parallel-connected control valve 12 is in this case in the bypass to the nonreturn valve 12 a, so that the pressure medium from the fluid accumulator 5 via the check 12 a valve can flow toward high-pressure chamber 3 in fast approach "Forward"; during the subsequent power stroke, the hydraulic connection to the fluid reservoir 5 via the check valve 12 a is interrupted and then the pressure medium can flow back into the fluid reservoir 5 via the control valve 12 a during the rapid “back” stroke. As an alternative to the electrically operated control valve 12 , a pneumatically operated control valve is also conceivable.

. The tenth embodiment shown in Figure 10 corresponds in material respects to the embodiments according to Figure 3- Figure 7, but with the following significant differences exist..:

• - Hydraulic connection between the high pressure chamber 3 and the frame-fixed fluid reservoir 5 through a coaxial bore in the plunger 6 .
• - Stroke displacement of the linear drive by axially displacing the plunger 6 and fixing it via the clamping connection 8 b on the cylinder flange 8 .
• - Pneumatic preloading of the fluid reservoir 5 through parallel connection to the pneumatic connection on the cylinder flange 8 .

The separation of low pressure and high pressure takes place via the tubular extension 1 b of the high pressure piston 1 and the seals 1 a and 6 a. During the Eilhubphase the pressure medium through radial bores passes in the high-pressure piston 1, on both sides of the high pressure seal 1 a, in the high pressure chamber. 3 During the power stroke phase, the high-pressure piston 1 remains in relation to the further shifting high-pressure chamber 3 , where the hydraulic connection to the fluid reservoir 5 is interrupted and the high pressure forms.

The eleventh exemplary embodiment shown in FIG. 11 is a variant of the exemplary embodiment according to FIG. 10. The function of the tubular extension 1 b of the high-pressure piston 1 takes on the tubular extension 6 b on the plunger 6 in this variant.

The twelfth embodiment shown in Fig. 12 is a variant of Ausführungsbei game according to Fig. 11. The tubular projection 6 b of the plunger 6 assumes in this case, due to its geometric shape, a valve function between the high-pressure chamber 3 and fluid accumulator 5. The power stroke phase is triggered depending on the path according to the current setting position of the plunger. This variant is particularly interesting for highly dynamic applications with reproducible, path-dependent generation of the power stroke.

The thirteenth exemplary embodiment shown in FIG. 13 is a variant of the exemplary embodiment according to FIG. 12. The valve function of the tubular extension 6 b on the plunger 6 is carried out in this case by the analogous extension 1 b on the high-pressure piston 1 .

The fourteenth embodiment shown in FIG. 14 is a variant of the exemplary embodiment according to FIG. 12 or FIG. 13. The valve function between the high pressure chamber 3 and the fluid reservoir 5 is essentially realized by radial connecting channels 6 c in the plunger 6 . In this variant, too, the power stroke is triggered depending on the travel according to the plunger setting.

Claims (19)

1. Linear drive with integrated pneumohydraulic pressure intensifier, with a high-pressure piston ( 1 ), during a rapid stroke "forwards" and "back", by an impressed bias pressure in a high-pressure chamber ( 3 ), against a stop on the moving return piston ( 4 ) and that the high-pressure chamber (3) at standstill of the high-pressure piston (1) by an obstacle, will be further driven by the pressure booster piston (2) or Rückhubkolben (4), a hydraulic connection is broken to the fluid accumulator (5), so that an annular surface ( 3 d) and one of the end faces of a plunger ( 6 ) or cylinder flange ( 8 ) which is fixed to the frame and which can build up effective high pressure on the high pressure piston ( 1 ). 2. Linear drive with integrated pneumohydraulic pressure intensifier according to claim 1, characterized in that the hydraulic connection to the fluid reservoir ( 5 ), through the high-pressure piston ( 1 ) when driving over the connecting channels ( 3 b), or through the electrically or pneumatically operated control valve ( 12 ). 3. Linear drive with integrated pneumohydraulic pressure intensifier according to claim 1, characterized in that a fluid reservoir ( 5 ) is provided to compensate for geometrically caused volume changes and leakages of the high pressure chamber ( 3 ), which is coupled to the high pressure chamber ( 3 ) and is moved. 4. Linear drive with integrated pneumohydraulic pressure intensifier according to claim 1, characterized in that the fluid accumulator (5) is fixed to the frame and is connected via the coiled-pressure hose (4 e) or connection channels (3 f) hydraulically connected to the high-pressure chamber (3). 5. Linear drive with integrated pneumohydraulic pressure intensifier according to claim 1 or 3, characterized in that the moving fluid reservoir ( 5 ) is filled with a compressible, elastic material. 6. Linear drive with integrated pneumohydraulic pressure intensifier according to claim 3, characterized in that the co-moving fluid accumulator (5) (c 5) or a rubber expansion joint (5 e) consists of a spring loaded corrugated metal hose. 7. Linear drive with integrated pneumohydraulic pressure intensifier according to claim 4, characterized in that the frame-fixed fluid reservoir ( 5 ) is designed as a bladder accumulator, rubber compensator ( 5 d) or spring-loaded metal corrugated hose ( 5 c). 8. Linear drive with integrated pneumohydraulic pressure intensifier according to one of claims 1 to 7, characterized in that the rapid stroke "before" or rapid stroke "back" is triggered by a pneumatic valve ( 11 ) and the power stroke is load-dependent, without switching a pneumatic valve switches on automatically. 9. Linear drive with integrated pneumohydraulic pressure intensifier according to one of claims 1 to 8, characterized in that a coiled hose ( 4 d) is used for venting the air-fluid separations ( 4 b) and ( 3 e). 10. Linear drive with integrated pneumohydraulic pressure intensifier according to one of An claims 1 to 9 characterized in that the Rückhubkolben (4) the connecting pipe (4 f) is fixedly coupled, and is led out of the cylinder flange (7) and thus in addition to the piston rod (1 b ) of the high-pressure piston ( 1 ) represents a further coupling interface. 11. Linear drive with integrated pneumohydraulic pressure intensifier according to one of claims 1 to 10, characterized in that the damping chamber ( 7 a) or ( 8 a) re relatively to the cylinder flange ( 7 ) or ( 8 ) can be axially displaced and fixed , so that from the current stroke end position of the high-pressure piston ( 1 ), the kinetic energy of the moving mass can be effectively absorbed. 12. Linear drive with integrated pneumohydraulic pressure intensifier according to one of An claims 1 to 11, characterized in that the cylinder flange (7), a tubular compensating piston is mounted (7 b) which is immersed in the extended high-pressure chamber (3) and geometrically in their movement-related Compensates for changes in volume. 13. Linear drive with integrated pneumohydraulic pressure intensifier according to one of claims 1, 2, 4, 7, 9 to 12, characterized in that the hydraulic connection of the high pressure chamber ( 3 ) and fluid reservoir ( 5 ), through which the pneumatic valve ( 11 ) in parallel switched electrically or pneumatically operated control valve ( 12 ) and the check valve ( 12 a), is manufactured or interrupted. 14. Linear drive with integrated pneumohydraulic pressure intensifier according to claim 1, characterized in that the high-pressure piston ( 1 ) is fixedly connected to the cylinder flange ( 7 ) and the plunger ( 6 ) in the axial direction in the cylinder flange ( 8 ) is movable so that the primary pressure acting on the pressure booster piston ( 2 ) or return stroke piston ( 4 ) is transformed according to the diameter difference between the high-pressure piston ( 1 ) and plunger ( 6 ) and becomes effective on the plunger ( 6 ). 15. Linear drive with integrated pneumohydraulic pressure intensifier according to claim 1, characterized in that for the path-dependent triggering of the power stroke or when changing the stroke position, the plunger ( 6 ) in the cylinder flange ( 8 ) is axially adjustable. 16. Linear drive with integrated pneumohydraulic pressure intensifier according to one of claims 1, 2, 4 or 7 to 15, characterized in that the hydraulic connection between the high-pressure chamber ( 3 ) and the fluid reservoir ( 5 ), through a connecting channel in the plunger ( 6 ) is realized. 17. Linear drive with integrated pneumohydraulic pressure intensifier according to claim 16, characterized in that the fluid reservoir ( 5 ) with the plunger ( 6 ) forms a unit. 18. Linear drive with integrated pneumohydraulic pressure intensifier according to one of claims 16 and 17, characterized in that the hydraulic connection between the high pressure chamber ( 3 ) and the fluid reservoir ( 5 ) via a tubular extension ( 1 b) or ( 6 b) on the high pressure piston ( 1 ) or plunger ( 6 ) is produced. 19. Linear drive with integrated pneumohydraulic pressure intensifier according to claim 1, characterized in that the function of the plunger ( 6 ) is taken over by the tubular extension ( 3 g) and the high pressure is supported directly on the cylinder flange ( 8 ).