EP1936208B1 - Pressure-driven hoisting device with self-locking spindle - Google Patents

Description

The invention relates to a pressure-medium-operated lifting device which can be used in hydraulically operated lifting devices, in which in the case of failure of the pressure energy, a mechanical blocking of the movement of a piston rod is required.

The barrier systems known from the prior art for blocking the movement of a piston rod can be divided into two main groups.

The first group can be associated with such locking systems, in which a locking device interacts directly with the piston rod of a linear pressure electricity consumer.

Known for this purpose mechanically acting locking systems based on a positive or non-positive blocking the movement of the piston rod, with positive-locking systems predominate.

From the publication DE 38 07 669 C2 a locking device for a continuously variable cylinder with a mechanical locking device is known, which is able to keep its position under load in any intermediate position reliable. This effect is achieved by means of a hollow piston rod with an inner profiling, in which a displaceable, axially spring-loaded rod with a recirculating ball channel with balls, which engage in the profiling of the piston rod, is arranged. The rod is connected to an actuating piston in an actuating cylinder, which ververschiebt the rod when pressurized with the pressure medium of the working cylinder so that the balls can rotate freely and are brought in the event of pressure drop in the blocking position, thus the piston rod is prevented from further movement.

Examples of the use of clamping heads, which act on the piston rod and prevent their movement, can be found, inter alia, in the publications DE 35 10 643 A1 and DE 38 11 225 C2 , Clamping heads are coupled as external units with a working cylinder, the clamping element, a spring-biased and displaceable by a servo piston for unlocking clamping body, acts in case of failure of the pressure of a medium from the outside to the piston rod and this fixed.

On the same principle, the device for clamping an axially moving rod according to the document is based DE 37 07 046 A1 , The clamping takes place by means of a clamping sleeve with outer cone, on which the inner cone of a spring-biased, axially displaceable piston acts. To release the movement of the rod, the pressure of a fluid is applied to the piston, whereby the clamping sleeve displaced against the spring bias, the clamping is released and the rod is thereby axially displaceable.

A working cylinder with a hollow piston rod, the blocking surface is arranged inside, is in the document DE 33 07 644 A1 described. In the hollow piston rod, a device for frictional clamping is installed, wherein clamping segments with friction linings on a support tube by a cone on an actuating rod which is connected to a control piston in a control cylinder and biased by a spring into the clamping position, for blocking against the inner wall of the Piston rod to be pressed.

In case of failure of the operating pressure of the fluid, the spring acts on the cone and as a result, the free movement of the piston rod is blocked.

A further clamping device for locking a piston rod of a piston-cylinder assembly is in the document DE 38 10 183 A1 described. The clamping device is in the piston arranged, wherein pressure-dependent radially movable inner disk segments unlock the piston. With applied pressure of the working fluid, the free movement of the piston is given. In case of pressure failure, the disk segments are moved by means of springs radially in the direction of the inner circumferential surface of the cylinder tube, act clamped and have a blocking of the movement of the piston rod to the sequence.

From the publication EP 1 170 512 B1 is a fluid-operated cylinder with mechanical path blocking in the unpressurized state, in which the blocking takes place by means of the interaction of the teeth of two spur gears as blocking elements. One of the spur gears is stationary with the housing of the working cylinder and the other with a rotatingly arranged threaded spindle of large pitch or the spindle of a ball screw. When pressurizing the working cylinder, the threaded spindle is in rotating motion after the gears of the spur gears were disengaged, thus the unlocking is done. The arranged on the threaded spindle spur gear is mounted with this form-fitting, displaceable and axially resilient. In case of pressure failure shifts by the action of a spring this spur gear so that its teeth with that of the fixed spur gear is engaged, whereby it comes to blocking, blocking the movement of the piston rod.

The disadvantage of this solution, in particular the relatively high production cost and a reduced efficiency of the working cylinder.

Belonging to the second group are locking systems that act indirectly via a positive coupling of the piston rod with a threaded spindle drive with self-locking as a locking device. The coupling of the piston rod with a threaded spindle is usually carried out by means of a threaded spindle suitable nut, which may be fixedly mounted, wherein the threaded spindle causes the axial movement of the piston rod, or the nut is designed as a running nut and the axial movement of the piston rod is effected by this.

A to be moved by means of the piston rod load is thus always coupled to the axial movement of the piston rod causing the gear member of the spindle drive.

In such Spindelhubelementen the self-locking spindle is set in rotating motion via an intermediate gear unit and by means of a suitable drive unit, whereby the load is moved to the piston rod via a guided nut or axial.verschobene spindle. Due to the positive coupling of the movable part of the lifting device with self-locking spindle, the movement of the piston rod is blocked in case of failure of the pressure energy and then held a load in the current position.

From the publication FR 2 150 595 A is known based on this principle fuse for a fluid cylinder. A partially hollow piston rod with a piston is coupled via a nut in this with a threaded spindle. The threaded spindle is coupled to an auxiliary motor which drives the threaded spindle. The auxiliary motor may be a hydraulic vane motor which may have separate ports for the pressure medium or its ports are connected to the ports of the cylinder. To limit the forces acting on the threaded spindle from the motor forces a double-acting bypass line is provided, are arranged in the spring-loaded pressure relief valves.
The limitation of the torque acting on the threaded spindle of the auxiliary motor is thus not adjustable for the achievement of a synchronism of piston movement and speed of the threaded spindle. The fuse is thus suitable only for a narrow range of a to be moved with the piston rod load.
If the load on the piston rod is too low, the piston will rush forward, causing it to jam in the thread mating between the nut and threaded spindle as well as at too large loads, in which the threaded spindle nachschiebt.

An analogous drawback, the device for locking the piston of a piston-cylinder unit according to the document DE 36 29 677 A1 on. A threaded portion of a piston rod with a piston cooperates with an internal thread of a pinch wheel. The pinch wheel is housed in a housing and is rotated in accordance with the movement of the piston. The vote of the speed of the pinch wheel on the movement of the piston takes place consuming each for a certain working pressure corresponding to the load to be moved by selective selection of the piston diameter, the piston rod of the spindle wheel and the truncated cone angle.
A problem-free adaptation to different, to be moved loads is not given.

Another embodiment of self-locking gear represent so-called roller screw drives, which act kinematically similar to spindle drives and can be designed as a planetary roller drive or roller screw drive. The difference between the two types consists only in the execution of the roles and their storage in a running nut. The roles of planetary roller drives have a thread, the rollers as locking elements of roller screws are provided with grooves on the circumference.

Known Spindelhubelemente with self-locking threaded spindle as a locking device do not allow a given exact axial positioning and are expensive to manufacture.
Just as complex are planetary roller drives or roller screw drives, which also have a low efficiency.

The object of the invention is the volume flow for a pressure-medium-operated lifting device with self-locking threaded spindle, which cooperates with a threaded partner on a hollow piston rod of a working cylinder, as a linear Druckstromverbraucher, and with a drive shaft of a coupled rotating pressure electricity consumer, so vote between two pressure stream consumers that a synchrony of the speed of the axial movement of the piston rod with the speed of the threaded spindle is ensured.

The object is solved by the features listed in claim 1. Preferred developments emerge from the subclaims.

A pressure-medium-operated lifting device according to the invention with self-locking threaded spindle essentially consists of a linear pressure flow consumer in the form of a working cylinder whose partially hollow piston rod cooperates positively with a threaded spindle drive with self-locking as a locking device and is coupled with a rotating Druckstromverbraucher with an output shaft. The piston rod of the linear pressure power consumer is coupled via the self-locking threaded spindle, which is positively and non-positively connected to the output shaft of the rotating pressure power consumer, with the rotating pressure flow consumer. With simultaneous supply of pressure energy to both pressure flow consumers, the axial movement of a load on the piston rod takes place in the main axis of the lifting device.
The movement of the load on the piston rod takes place exclusively by means of the linear pressure flow consumer by controlling the flow of fluid to the respective pressure consumer is controlled so that the rotating Druckstromverbraucher only the self-locking screw speed controlled, according to the speed of the axial movement of the piston rod with the least friction.
The speed of the self-locking threaded spindle is thus adapted to the speed of the axial movement of the piston rod and depends on the pitch of the thread of the self-locking threaded spindle. The amount of fluid to be supplied to the rotating pressure flow consumer is thereby determined, thus ensuring the balance between the axial movement of the piston rod and the tracking of the self-locking threaded spindle is and the load on the piston rod only or almost only, by means of the linear Druckstromverbrauchers on the piston rod is moved.

Since the efficiency of the linear Druckstromverbrauchers during axial movement of the piston rod is substantially larger than that when moving the piston rod by means of self-locking screw, the overall efficiency of the lifting device increases to the extent that the adjustment of the supply of the fluid flow to the two Druckstromverbrauchern is present that the self-locking threaded spindle must be tracked only to the extent of overcoming the internal friction, without this being involved in the actual movement of the load on the piston rod.

The optimum balance of the respective amount of supply of the fluid flow to the linear Druckstromverbraucher and the rotating Druckstromverbraucher carried by division of the supplied fluid flow of the pressure medium, wherein in the supply lines to the pressure flow loads, preferably in the supply line to the linear pressure flow consumer, a flow control valve is arranged, with the partial fluid flow is throttled and the speed of the axial movement of the piston rod of the linear Druckstromverbrauchers is synchronized with the speed of, driven by the rotating Druckstromverbraucher, self-locking threaded spindle.

An optimal balance of the fluid flow to the rotating pressure flow consumer and the linear pressure flow consumer is present if the following mathematical relationships are met: $$\frac{Q_{\mathit{AZ}}\times {\eta }_v}{A_{\mathit{AZ}}}=\frac{Q_R\times {\eta }_v\times p}{V}=v_{\mathit{stroke}}$$

Q_AZ =

Zustrommenge zum linearen Druckstromverbraucher

Q_R =

Zustrommenge zum rotierenden Druckstromverbraucher

A_AZ =

Kolbenfläche des linearen Druckstromverbrauchers

V =

Schluckvolumen des rotierenden Druckstromverbrauchers

η _v =

volumetrischer Wirkungsgrad

p =

Steigung der Gewindespindel

V_Hub =

Hubgeschwindigkeit

It means here:

Q _AZ =

Flows to the linear pressure current consumer

Q _R =

Outlets to the rotating Druckstromverbraucher

A _AZ =

Piston surface of the linear pressure electricity consumer

V =

Suction volume of the rotating pressure electricity consumer

η _v =

volumetric efficiency

p =

Slope of the threaded spindle

V _stroke =

Lifting speed

The advantages of the invention are in particular that the overall efficiency of the fluid-operated lifting device is substantially greater than that of a rotating Druckstromverbrauchers of about 35 percent, if the load would be moved to the piston rod alone on the self-locking screw. It may be achieved an overall efficiency in the vicinity of the lying for a linear pressure flow consumer size, which is usually at least 90 percent.

Fig. 1

als Halbschnittdarstellung der druckmittelbetriebenen Hubvorrichtung mit selbsthemmender Spindel

und

Fig. 2

als Schnitt im Bereich des rotierenden Druckstromver-brauchers mit Darstellung der Fluidkanäle und Bohrungen für den Zu- und Ablauf des Druckmediums

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

Fig. 1

as a half-sectional view of the fluid-operated lifting device with self-locking spindle

and

Fig. 2

as a section in the area of the rotating Druckstromver-consumer with representation of the fluid channels and holes for the inlet and outlet of the pressure medium

explained in more detail.

An example executed pressure-medium-operated lifting device is after Fig.1 essentially of a linear pressure current consumer 1 and a rotating pressure current consumer 2, which are designed as a structural unit and coupled directly to one another. The linear Druckstromverbraucher 1 has a conventional, partially hollow piston rod 3, in which a self-locking threaded spindle 4 is arranged, which cooperates with a threaded partner 5 in a working piston 6. The threaded spindle 4 is connected by means of a non-positive and positive connection 7 with an output shaft 8 of the rotating Druckstromverbrauchers 2. The supply and discharge of a pressure medium for operating the pressure-medium-operated lifting device takes place in a known manner via a first connection 9 and a second connection 10, which in Fig.2 is shown. If a pressure medium is supplied via the first port 9 when the piston rod 3 is retracted, then this will be provided with working chambers with rotor blades 12 in a cam disc 13 via channels 11 rotating Druckstromverbrauchers 2 supplied, whereby this is set in rotating motion. At the same time, the supply of the pressure medium to a piston chamber 14, so that the working piston 6 of the linear pressure flow consumer 1 causes the axial extension movement of the piston rod 3. The amount of Druckmediumls supplied to the rotating Druckstromverbraucher 2 is known to determine its speed and thus depending on the pitch value of the self-locking screw 4, the speed of the axial movement of a load on the piston rod. 3
To optimize the efficiency of the pressure-medium-operated lifting device with self-locking threaded spindle 4, the speed of the extending piston rod 3 and the rotational speed at the output shaft 8 of the rotating Druckstromverbrauchers 2 synchronized by the piston chamber 14 to be supplied amount of the pressure medium is adjusted by means of a first flow control valve 15 in the flow.

The existing in a piston rod chamber 16 pressure medium is passed upon extension of the piston rod 3 via a bore 17 and a gap 18 of a double-walled cylinder tube 19 in a circulation channel 20 and after Fig.2 further via a drain hole 21 and a check valve 22 in a drain passage 23, in which also via the bores 24 from the rotating Druckstromverbraucher 2 effluent pressure medium to the drain-oriented second port 9 is performed.

The efficiency of the pressure-medium-operated lifting device with self-locking threaded spindle 4 is optimal when the load is carried on the piston rod 3 exclusively from the linear Druckstromverbraucher 1 and the threaded spindle 4 is followed by the rotating Druckstromverbraucher 2 only the extension movement of the piston rod 3.

For retracting the piston rod 3, the supply of the pressure medium via the second port 10 and the outflow of the pressure medium via the first port 9 takes place. The pressure medium is here after Fig.2 Via a further channel 25, the circulation channel 20, the intermediate space 18 and the bore 17, the pressure medium passes into the piston rod chamber 16. By means of a second flow control valve 26 is via the drain passage 23 to the linear Druckstromverbraucher 1 and fed via the bores 24 the rotating Druckstromverbraucher the amount of pressure medium to be supplied to the piston rod chamber 16 adapted to again synchronize the rotational speed of the output shaft 8 of the rotating Druckstromverbrauchers 2 with the speed of the retracting piston rod 3 of the linear Druckstromverbrauchers 1.

The power control valves 15; 26 are also when draining the pressure medium from the rooms 14; 16 effective.

In case of failure of the pressure of the pressure medium, the load recorded on the piston rod 3 is held by the self-locking threaded spindle 4 in cooperation with the threaded partner 5 in the working piston 6, since the threaded spindle 3 can no longer rotate due to the self-locking and thus no axial movement of the piston rod. 3 more is possible.

From the FIGS. 1 and 2 further details of the pressure-medium-operated lifting device with self-locking spindle out. Thus, the threaded spindle 4 is mounted, for example via tapered roller bearings 27 of the output shaft 8 of the rotating Druckstromverbrauchers 2, wherein the tapered roller bearings 27 are mounted in a left outer housing 28. The left outer housing 28 is positively and positively connected via a center housing 29 and the cam 13 with a right outer housing 30. The present in the left outer housing 28, the middle housing 29 and the right outer housing 30 existing inlet and outlet channels in the form of the drain hole 21 and the further channel 25 are coupled to each other via connecting pipes 31.

Used reference signs

1

linear pressure current consumer

2

rotating pressure current consumer

3

piston rod

4

screw

5

thread partner

6

working piston

7

non-positive and positive connection

8th

output shaft

9

first connection

10

second connection

11

channels

12

rotors wings

13

cam

14

piston chamber

15

first power control valve

16

Piston rod space

17

drilling

18

gap

19

double-walled cylinder tube

20

circulation channel

21

drain hole

22

check valve

23

drain channel

24

drilling

25

another channel

26

second power control valve

27

Tapered roller bearings

28

left outer casing

29

center housing

30

right outer casing

31

connecting pipes

Claims (3)

1. Pressure medium-operated lifting device with a self-locking threaded spindle (4), which cooperates with a thread partner (5) on a partially hollow piston rod (3) of a working cylinder as a linear pressure flow consumer (1), wherein the linear pressure flow consumer (1) is coupled to a rotating pressure flow consumer (2) with a driven shaft (8), wherein the driven shaft (8) is connected in a positive and non-positive manner to the threaded spindle (4) of the linear pressure flow consumer (1), wherein synchronism is achieved between the speed of the axial movement of the piston rod (3) of the linear pressure flow consumer (1) and the rotational speed of the threaded spindle (4) driven by the rotating pressure flow consumer (2), characterised in that
   a pressure flow of a fluid, supplied to the pressure medium-operated lifting device, is divided into partial fluid flows to the linear pressure flow consumer (1) and to the rotating pressure flow consumer (2), wherein the quantity of the partial fluid flow to be supplied to a piston chamber or piston rod chamber (14; 16) of the linear pressure flow consumer (1) is constricted by means of a first (15) and a second (26) flow control valve in supply lines (11; 25) to the linear pressure flow consumer (1).
2. Pressure medium-operated lifting device with a self-locking threaded spindle (4) as claimed in claim 1, characterised in that
   the linear pressure flow consumer (1) and the rotating pressure flow consumer (2) are acted upon by the pressure medium at the same time.
3. Pressure medium-operated lifting device with a self-locking threaded spindle (4) as claimed in claim 1 and 2, characterised in that,
   the synchronisation of the speed of the axial movement of the piston rod (3) with the rotational speed of the self-locking threaded spindle (4) is such that the movement of a load on the piston rod (3) is only the result of the supply of a pressure medium to the respective working chamber of the linear pressure flow consumer (1), and wherein the threaded spindle (4) is made to follow up corresponding to the speed of the axial movement of the piston rod (3) in a thread partner (5) in the working piston (6) via a driven shaft (8) of the rotating pressure flow consumer (2) with the lowest friction.

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