Balancer

Abstract

The invention relates to a balancer (1) for raising, holding and lowering a load, comprising a cable drum (7) which can be rotated in a manner actuated by pressure medium and has a cable for bearing the load, which cable can be unwound from and wound onto said cable drum (7), and has a device for emergency braking of the cable drum (7) if a defined rotational speed is exceeded, which device for emergency braking comprises at least one locking element (16) which is fastened to the cable drum (7), is held in a freewheeling position in a spring-loaded manner and can be moved into a deployed locking position in a manner which is actuated by centrifugal force, in which locking position the rotation of the cable drum (7) is blocked by virtue of the fact that the locking element (16) is in engagement with a stop which is stationary relative to the cable drum (7). The balancer (1) according to the invention is distinguished by the fact that, after its triggering, the locking element (16) is held in a deployed position when said locking element (16) and the stop which interacts with it move out of engagement.

Claims

1. A balancer for raising, holding and lowering a load, comprising: a cable drum actuatable by a pressure medium, a cable for bearing the load, the cable being unwindable from and windable onto said cable drum, a device for emergency braking of the cable drum if a defined rotational speed of the cable drum is exceeded, wherein the device for emergency braking comprises at least one triggerable locking element fastened to the cable drum, the locking element movable from in a freewheeling position to a deployed locking position actuatable by centrifugal force, in which deployed locking position a rotation of the cable drum is blocked by the locking element being in engagement with a stop which is stationary relative to the cable drum, wherein, before being triggered, the locking element is held in the freewheeling position by a retaining spring and movement from the freewheeling position towards the deployed locking position is biased by the retaining spring, wherein, after being triggered, the locking element is held in the deployed locking position by the retaining spring and movement from the deployed locking position towards the freewheeling position is biased by the retaining spring, and wherein the cable drum is arranged rotatably and/or axially displaceably within a stationary cage or a stationary cylinder or a stationary housing, and in that, in the deployed locking position after being triggered, the locking element engages into a locking aperture of the stationary cage or the stationary cylinder or the stationary housing.

2. The balancer as claimed in claim 1, wherein the retaining spring is attached to the locking element at a spacing from a pivot pin of the locking element, wherein, when the locking element is in the freewheeling position, the retaining spring is arranged to bias pivoting of the locking element about the pivot pin towards the deployed locking position, and wherein, when the locking element is in the deployed locking position, the retaining spring is arranged to bias pivoting of the locking element about the pivot pin towards the freewheeling position.

3. The balancer as claimed in claim 1, wherein the locking element comprises a pivotable locking lever which is movable by centrifugal force from the freewheeling position to the deployed locking position.

4. The balancer as claimed in claim 1, wherein the retaining spring is attached to the locking element at a spacing from a pivot pin of the locking element, wherein the retaining spring holds the locking element in the deployed locking position if the locking element is deflected beyond a dead center position.

5. The balancer as claimed in claim 4, wherein the retaining spring holds the locking element in the freewheeling position in a non-actuated manner.

6. The balancer as claimed in claim 1, wherein the device for emergency braking comprises, furthermore, at least one centrifugal lever which is articulable pivotably on the cable drum and which acts on the locking element in an actuating manner.

7. The balancer as claimed in claim 6, wherein the centrifugal lever is held via the locking element in a pivoted-in rest position.

8. The balancer as claimed in claim 6, wherein, in the freewheeling position, the centrifugal lever and the locking element extend approximately tangentially with respect to the axis of the cable drum on a circumference of the cable drum and, upon deflection, perform a pivoting movement in the opposite direction.

9. The balancer as claimed in claim 1, wherein the device for emergency braking of the cable drum is provided on an end side of the cable drum.

10. A balancer for raising, holding and lowering a load, comprising: a cable drum actuatable by a pressure medium, a cable for bearing the load, the cable being unwindable from and windable onto said cable drum, a device for emergency braking of the cable drum if a defined rotational speed of the cable drum is exceeded, wherein the device for emergency braking comprises at least one triggerable locking element fastened to the cable drum, the locking element movable from a freewheeling position to a deployed locking position actuatable by centrifugal force, in which deployed locking position a rotation of the cable drum is blocked by the locking element being in engagement with a stop which is stationary relative to the cable drum, wherein, before being triggered, the locking element is held in the freewheeling position by a retaining spring and movement from the freewheeling position towards the deployed locking position is biased by the retaining spring, wherein, after being triggered, the locking element is held in the deployed locking position by the retaining spring and movement from the deployed locking position towards the freewheeling position is biased by the retaining spring, wherein, after being triggered, the rotation of the cable drum is blocked by the locking element being in positive mechanical engagement with the stop, and wherein the cable drum is arranged rotatably and/or axially displaceably within a stationary cage or a stationary cylinder or a stationary housing, wherein the stationary cage or the stationary cylinder or the stationary housing provides the stop.

11. The balancer as claimed in claim 10, wherein the retaining spring is attached to the locking element at a spacing from a pivot pin of the locking element, wherein, when the locking element is in the freewheeling position, the retaining spring is arranged to bias pivoting of the locking element about the pivot pin towards the deployed locking position, and wherein, when the locking element is in the deployed locking position, the retaining spring is arranged to bias pivoting of the locking element about the pivot pin towards the freewheeling position.

12. The balancer as claimed in claim 10, wherein the locking element comprises a pivotable locking lever which is movable by centrifugal force from the freewheeling position to the deployed locking position.

13. The balancer as claimed in claim 10, wherein the retaining spring is attached to the locking element at a spacing from a pivot pin of the locking element, wherein the retaining spring holds the locking element in the deployed locking position if the locking element is deflected beyond a dead center position.

14. The balancer as claimed in claim 13, wherein the retaining spring holds the locking element in the freewheeling position in a non-actuated manner.

15. The balancer as claimed in claim 10, wherein the device for emergency braking comprises, furthermore, at least one centrifugal lever which is articulable pivotably on the cable drum and which acts on the locking element in an actuating manner.

16. The balancer as claimed in claim 15, wherein the centrifugal lever is held via the locking element in a pivoted-in rest position.

17. The balancer as claimed in claim 15, wherein, in the freewheeling position, the centrifugal lever and the locking element extend approximately tangentially with respect to the axis of the cable drum on a circumference of the cable drum and, upon deflection, perform a pivoting movement in the opposite direction.

18. The balancer as claimed in claim 10, wherein the device for emergency braking of the cable drum is provided on an end side of the cable drum.

Description

(1) In the following text, the invention will be explained with reference to the appended drawings, in which:

(2) FIG. 1 shows a longitudinal section through the balancer according to the invention,

(3) FIG. 2 shows a perspective illustration of the cage which surrounds the cable drum, and of the device for emergency braking of the cable drum in its position with regard to the cage, and

(4) FIGS. 3a-3c in each case show end views of the cable drum with the device for emergency braking, which figures in each case illustrate different states of the locking element and the centrifugal lever.

(5) Reference is made first of all to FIG. 1. Said figure shows a balancer 1 as compressed air balancer in longitudinal section. The balancer 1 comprises a cylindrical housing 2 and connection covers 3 which are mounted on the housing 2 on the end side. An axle 4 which is arranged fixedly in terms of rotation and is configured partially as a ball bearing spindle 5 extends in the longitudinal center axis of the balancer 1. A spindle nut 6 which is connected fixedly to a cable drum 7 so as to rotate with it is arranged rotatably on the ball bearing spindle 5. A steel cable can be wound up onto and unwound from the cable drum. For reasons of simplicity, the steel cable is not shown in the drawing.

(6) The housing 2 comprises a chamber 8 which is loaded with compressed air 22 and in which a piston 9 is arranged such that it can be displaced along the axle 4. The piston 9 is sealed by means of a circumferential sealing lip 10a against the enclosing wall of the cylindrical chamber 8. The piston 9 is sealed on the inner side against the axle 4 by way of a second sealing lip 10b. On its side which faces the cable drum, said piston 9 acts on the cable drum 7 via an axial ball bearing 11. The axial ball bearing 11 permits a relative rotation between the piston 9 and the cable drum 7. On account of the interaction of the stationary ball bearing spindle 5 or that part of the axle 4 which is configured as a ball bearing spindle 5 and the spindle nut 6 which is connected fixedly to the cable drum 7 so as to rotate with it, the cable drum 7 rotates about the axle 4 as a result of the axial displacement of the piston 9 and is at the same time displaced axially, to be precise by the extent to which a cable which is coiled onto the cable drum 7 is unwound or wound up.

(7) Here, the lead of the ball roller track in the ball bearing spindle 5 is dimensioned in such a way that the cable which is coiled up on the cable drum always exits at the same point from a cable outlet opening which is provided for this purpose.

(8) On that end side of the cable drum 7 which faces away from the piston 9, a mounting plate 12 is provided which is connected fixedly to the cable drum 7 so as to rotate with it. The cable drum 7 is centered within a cylindrical cage 13 which is arranged or flange-connected in a rotationally fixed manner within the housing.

(9) A perspective illustration of the cage 13 can be seen from FIG. 2. Said cage 13 is of approximately cylindrical configuration and, on its side which faces the piston 9, is flange-connected to the housing 2 by way of a fastening flange 14. The circumferential face of the cage 13 is provided with a multiplicity of apertures 15 which, as will still be explained in the following text, interact with a locking element 16.

(10) The locking element which is denoted by 16 and a centrifugal lever 17 are mounted in a pivotably movable manner on the mounting plate which is denoted by 12, is connected, as has been mentioned, fixedly to the end side of the cable drum 7 so as to rotate with it, is of approximately annular configuration and is inserted into the circumference of the cage 13. The pivot pins 18, 19 of the locking element 16 and of the centrifugal lever 17 extend approximately parallel to the axle 4 which at the same time defines the rotational axis of the cable drum 7.

(11) The locking element 16 and the centrifugal lever 17 are arranged at a spacing on the circumference of the mounting plate 12 in such a way that the locking element 16 and the centrifugal lever 17 extend approximately tangentially with respect to a circular circumference. The pivoting movement which can be performed by the locking element 16 and by the centrifugal lever 17 in each case takes place in the opposite direction, the locking element 16 and the centrifugal lever 17 bearing approximately against the inner circumference of the annular mounting plate 12 in the freewheeling position of said locking element 16 and centrifugal lever 17. This position is shown, in particular, in FIG. 3a. In this position, the locking element 16 lies above the centrifugal lever 17, as viewed from the inside to the outside. In this position, the locking element 16 is held by a retaining spring 20. The retaining spring 20 likewise extends tangentially, in relation to the inner circumference of the mounting plate 12, or tangentially with respect to a circular circumference which extends concentrically to the axle 4. The retaining spring 20 is attached to the locking element 16 eccentrically at a spacing from the pivot pin 19, to be precise in such a way that, in the initial position which is shown in FIG. 3a, the locking element 16 is held via the retaining spring 20 in the pivoted-in position, that is to say experiences a moment about the pivot pin 19 counter to the clockwise direction (the rotational direction is in relation to the view in the figures) and experiences an opposed moment if the locking element 16 is pivoted radially outward via the dead center position. The dead center position is that position, in which both fastening points of the retaining spring 20 and the pivot pin 19 are arranged so as to be flush with one another. In the dead center position, an automatic restoring movement of the locking element 16 into the freewheeling position is no longer possible.

(12) If the cable drum 7 then experiences, for example, a rotation counter to the clockwise direction, which rotation exceeds a defined rotational speed which is predetermined by the force of the retaining spring 2, the centrifugal lever 17 is likewise deflected counter to the clockwise direction. Here, the free end 21 of the centrifugal lever 17 presses the locking element 16 radially outward beyond the dead center point of the retaining spring 20, with the result that the locking element 16 engages in a locking manner into one of the apertures 15 with stop 23 of the cage 13. Here, the retaining spring 20 holds the locking element 16 in the radially deployed locking position. In the described exemplary embodiment, the device for emergency braking is configured as a securing means against unintentional winding up of the cable, and as an alternative can also be configured as a fall arrester.

(13) As can be seen from FIG. 2, the locking element 16 arrests the cable drum 7 counter to the clockwise direction (in relation to the view in FIG. 2). In the case of a correspondingly mirror-inverted design of the arrangement of locking lever 16 and centrifugal lever 17, arresting of the rotation in the clockwise direction would be possible.

(14) An unlocking action is possible only in the case of a correspondingly manually actuated restoring of the locking element 16.

(15) The chamber 8 of the balancer 1 is loaded with compressed air via a pressure medium connection (not shown). The pressure within the chamber 8 is approximately in equilibrium with the force which is exerted on the piston 9 via the axial ball bearing 11 by the cable drum 7 if a load is suspended. A movement of the cable drum 7 takes place via a control operation of the pressure loading of the chamber 8 which brings about an axial movement of the piston 9 and a rotation of the cable drum 7 about its axis. In the process, the cable (not shown) is wound up and unwound. In the case of sudden loss of the load, this force equilibrium is disrupted such that the cable drum 7 exceeds a defined limiting rotational speed. As a result, a deflection of the centrifugal lever 17 about the pivot pin 18 and therefore also a deflection of the locking element 16 about the pivot pin 19 are brought about. The rotational speed and/or centrifugal force, at which a deflection of this type is possible is dependent on the characteristic of the retaining spring 20 and the mass of the centrifugal lever 17.

LIST OF DESIGNATIONS

(16) 1 Balancer 2 Housing 3 Connection cover 4 Axle 5 Ball bearing spindle 6 Spindle nut 7 Cable drum 8 Chamber 9 Piston 10a, b Sealing lips 11 Axial ball bearing 12 Mounting plate 13 Cage 14 Fastening flange 15 Apertures 16 Locking element 17 Centrifugal lever 18 Pivot pin 19 Pivot pin 20 Retaining spring 21 Free end of the centrifugal lever