EP1150913B1 - Device for preventing uncontrolled acceleration of an elevator car installed in an elevator installation - Google Patents

Abstract

A device for preventing uncontrolled acceleration of an elevator car installed in an elevator installation. The device has a limiting cable guided over rollers in a direction of movement of the elevator car. A braking device which is joined to the elevator car is connected to the limiting cable by a release and brakes the elevator car in both a downward and upward direction when the limiting cable transmits a predetermined release force to the release. A speed limiter is connected to one of the rollers and stops the roller when the traveling speed of the elevator car exceeds a predetermined limiting speed either in a downward or upward direction. The release of the braking device is connected by a slide connection to the limiting cable for limiting the force transmitted to the release so that the limiting cable slides through on the side connection when a force is significantly larger than the release force required for releasing the braking device is transmitted from the limiting cable to the release of the braking device.

Description

The invention relates to a device for preventing uncontrolled acceleration of a car of an elevator installation both in the upward direction and in the downward direction.

In elevator systems, a car is usually connected via a cable and a drive pulley, via which the drive takes place, with a counterweight. In order to ensure a malfunction, such as the failure of the drive means, that the car is not accelerated uncontrollably by the weight difference between the car and the counterweight, a corresponding safety device is prescribed. Since the counterweight is usually designed to balance at half the allowed payload of the car, uncontrolled acceleration may occur in both the downlink and uplink depending on whether the halfway payload of the car has been exceeded or undershot. The safety device must therefore respond both in an uncontrolled acceleration in the downward direction and in the upward direction.

An apparatus for preventing uncontrolled accelerations of a car in an elevator system according to the preamble of claim 1 is for example from the EP 0 440 839 A1 known. The resulting from this document safety device responds both in an uncontrolled acceleration in the downward direction and in the upward direction. For detecting the uncontrolled acceleration of the elevator car, a governor rope independent of the drive cable is provided, which circulates endlessly over an upper deflecting roller and a lower deflecting roller. At the lower pulley weight is provided to keep the governor rope always taut. At the upper pulley there is a speed limiter. The car is connected via a trigger serving as an actuating lever with the governor rope, so that the governor rope is always carried along undisturbed moving the car with this and thus the rotational speed of the upper pulley speed of the car is proportional. The speed limiter detects the rotational speed of the upper guide roller and is designed so that it blocks when exceeding a limit rotational speed of the upper guide roller, so that the upper guide roller is stopped. Since the governor rope is still carried along with the elevator car, the governor rope slips over a groove provided in the upper deflecting roller and experiences a frictional resistance, so that a release force is transmitted to the trigger of the braking device via the governor cable. Then the brake device responds and presses brake shoes against a guide rail of the elevator system, so that the car is decelerated and intercepted. In this case, different brake shoes for braking or interception of the car in the downward direction or upward direction are provided.

As will be shown in more detail below with reference to FIGS. 10 and 11, the force acting on the cable strand of the governor rope connected to the trigger is to a considerable extent dependent on whether the car moves in the downward direction or in the upward direction. As can be seen, when the car moves, the wire rope of the governor rope connected to the trigger pulls directly upwards against the weight of the lower deflection roller. In a movement of the car down, however, pulls connected to the trigger wire rope of the governor rope on the stationary upper pulley on the weight of the lower pulley, so that in this case the force acting on the cable connected to the cable strand force increases significantly due to friction.

The dimensioning of the securing device, in particular the weight associated with the lower deflection roller and the geometry of the keyway provided on the upper deflection roller, over which the governor rope is pulled when the upper deflection roller is stopped, must therefore be oriented towards the braking action of the elevator during the upward movement because in this case the release force is lower. On the other hand, however, this means that the release force is so great in a downward movement of the car that considerable problems in the dimensioning of the governor rope and the trigger of the braking device occur because the governor rope and the trigger must withstand this very high release force in the downward direction.

In the EP 0 440 839 A1 It is proposed to arrange a compensation spring in the governor rope above the trigger. However, this compensation spring increases the already too large release force in the downward direction even more and is therefore unfavorable.

The invention has for its object to provide a device for preventing uncontrolled accelerations of a car of an elevator system, in which the initiated in the trigger of the braking device release force is limited.

The object is achieved by the characterizing features of claim 1 in conjunction with the generic features.

According to the invention, it is proposed to connect the trigger of the braking device with the governor rope via a slip connection so that the governor rope slips on the slip connection when a force is transmitted from the governor cable to the trigger of the braking device, which is considerably larger than that required to trigger the braking device Triggering force is. By the proposed solution according to the invention, the maximum initiated release force limited and thus the trigger of the braking device and the governor rope protected from overloading. In this way, the components of the device can be designed so that on the one hand a sufficient release force is generated to intercept an acceleration of the car in the upward direction to safely trigger the trigger of the braking device, on the other hand, however, the triggering force is limited in a trapping of the car in the downward direction, which prevents an overload of the trigger and the limiter rope.

Claims 2 to 10 relate to advantageous developments of the invention.

The slip connection can be adjusted so that the governor rope slips on the slip connection only when braking the car in the downward direction. When the car is slowed down in the upward direction, the governor rope then slips over the fixed upper deflection roller as before, without triggering the sliding connection according to the invention. Since the governor rope as described when braking the car in the downward direction a much larger force acts as when braking in the upward direction, it is sufficient that the slip slip through in the downward direction. In this case, the slip connection can be adjusted with some safety distance above the release force required for triggering the braking device.

The slip connection can be arranged directly below the cable connector, which connects the free ends of the governor rope together.

The slip connection preferably consists of a base plate and a biased against the base plate with a predetermined clamping force clamping plate, wherein the Begrenzerseil is clamped between the base plate and the clamping plate.

To generate the clamping force is at least one clamping screw, which passes through a hole in the clamping plate and can be screwed into a thread of the base plate. The screwing depth and thus the clamping force is limited by a clamping stop.

The clamping force can be generated from a clamped between the base plate and a projection of the clamping screw tension spring, which preferably consists of a plurality of stacked disc springs. The clamping stop can be formed by a sleeve surrounding the clamping screw.

The limiter rope is preferably guided on a surface of the base plate and / or the clamping plate in a groove, which has a preferably triangular cross-sectional contour. At the ends of the base plate or the clamping plate, the groove preferably opens in an opening region which opens both in the direction of the surface and also transversely to the surface of the base plate or the clamping plate.

The trigger of the braking device is connected to either the clamping plate or the base plate.

Fig.

1 ein Ausführungsbeispiel der erfindungsgemäßen Vorrichtung in einer Gesamtansicht;

Fig. 2

das Begrenzerseil, den Seilverbinder und die Rutschverbindung in einer Montagedarstellung;

Fig. 3

das Begrenzerseil, den Seilverbinder und die Rutschverbindung in montiertem Zustand;

Fig. 4

eine Draufsicht auf die Rutschverbindung;

Fig. 5

einen Schnitt entlang der Linie A-A in Fig. 4;

Fig. 6

einen Schnitt entlang der Linie B-B in Fig. 4;

Fig. 7

eine Draufsicht auf die Basisplatte der Rutschverbindung;

Fig. 8

eine Seitenansicht der Basisplatte der Rutschverbindung; und

Fig. 9

einen Schnitt entlang der Linie A-A in Fig. 8.

An embodiment of the invention will be described below with reference to the drawing. In the drawing show:

FIG.

1 shows an embodiment of the device according to the invention in an overall view;

Fig. 2

the governor rope, the cable connector and the slip connection in an assembly view;

Fig. 3

the governor rope, the cable connector and the slip connection in the assembled state;

Fig. 4

a plan view of the slip connection;

Fig. 5

a section along the line AA in Fig. 4;

Fig. 6

a section along the line BB in Fig. 4;

Fig. 7

a plan view of the base plate of the slip connection;

Fig. 8

a side view of the base plate of the slip connection; and

Fig. 9

a section along the line AA in Fig. 8.

1 shows the device according to the invention for preventing uncontrolled acceleration of a car of an elevator installation, initially in an overall representation.

From a car 1, only the support frame 2 is shown. The support frame 2 of the car 1 is guided on an upper guide 3 and on a lower guide 4 on a guide rail 5 only indicated by the dashed line along a vertical trajectory. The car 1 is suspended from a conveyor rope, not shown, which is deflected at the upper end of the elevator shaft via a drive pulley and connected to a counterweight. The car is driven by the drive pulley. The counterweight is usually sized so that the counterweight with the car 1 is then in equilibrium when the car 1 is subjected to about half its maximum payload. In the event of a malfunction, in particular in the event of a failure of the drive device, the car 1 can be accelerated uncontrollably due to the weight difference between the car 1 and the counterweight. If the car 1 is filled with less than half its payload, this acceleration is in the upward direction. If, however, the car 1 is filled with more than half its payload, this uncontrolled acceleration takes place in the downward direction. To prevent this uncontrolled acceleration, a braking device 6 is provided, which controls the uncontrolled acceleration in both upward and downward prevented in the downward direction and can be triggered via a trigger 7. A braking device of a similar type is for example from the DE 296 19 729 U1 and the EP 0 825 145 A1 known and will be described only roughly.

The trigger 7 consists of a hinged to a suspension 8 rocker arm 9 and connected to the rocker arm 9 linkage 10 which engages a mounted on a bearing 11 turntable 12. When tilting the rocker arm 9 in Fig. 1 upwards, the linkage 10 is moved upward and rotates the turntable 12 so that a first brake element 13 is pressed into contact with the guide rail 5 only indicated, so that the guide rail 5 between a brake shoe 14 and the first brake element 13 is clamped. The clamping force is determined by two acting on the brake shoe 14 disc spring assemblies 15 and 16. The deceleration of the car 1 is then carried out by chip removal on the only indicated guide rail 5. The above-described braking process concerns the braking of the car 1 in an uncontrolled acceleration in the downward direction.

To brake or intercept the car 1 in an uncontrolled acceleration upward movement of the rocker arm 9 is tilted in Fig. 1 down and the linkage 10 is moved down. As a result, a second brake element 17 is brought into engagement with the guide rail 5, so that the guide rail 5 is clamped between the brake shoe 14 and the second brake element 17.

The triggering of the trigger 7 of the braking device 6 via a limiter 18, with which the car 1 is connected via the trigger 7 of the brake device 6. The limiter rope 18 is formed in the embodiment as an upper guide roller 19 and a lower guide roller 20 endlessly circulating rope. By a via a linkage 22 which is articulated to a bearing 23, on the lower pulley 20 acting weight 21, the governor rope 18 between the upper guide roller 19 and the lower guide roller 20 taut. The free ends 24 and 25 of the Begrenzerseils 18 are connected to each other via a cable connector 26.

At the upper guide roller 19 is a speed limiter 27, which stops the upper guide roller 19 when a predetermined rotational speed is exceeded, d. H. blocked. Such speed limiter 27 are known in different designs.

During proper operation of the elevator system, the governor rope 18 is carried along with the car 1 uniformly and the upper deflecting roller 19 is in its unlocked state. Since the speed of the governor rope 18 corresponds to the speed of the car 1, the rotational speed of the upper deflecting roller 19 is proportional to the speed of the car 1. If the rotational speed of the upper deflection roller 19 exceeds a predetermined limit value, the speed limiter 27 blocks the upper deflection roller 19 so that the governor rope 18 is in sliding contact with the stopped upper deflection roller 19. Thereby, a force component is exerted on the governor rope 18, which transmits it to the trigger 7 of the braking device 6, which finally leads to the triggering of the braking device 6.

The problem with such a device for preventing uncontrolled acceleration of the car 1 is that the governor rope 18 acts in a downward movement of the car 1, a significantly greater braking force than during a movement of the car 1 in the upward direction. This situation will be explained in more detail below with reference to Figures 10 and 11.

10 shows the force relationships on the governor rope 18 or on the upper deflecting roller 19 and the lower deflecting roller 20 in the case of deceleration of the car 1 in the downward direction. After stopping the upper guide roller 19, the left in Fig. 1 and 10 strand 18a of the governor rope 18 is initially carried down. Both on the left strand 18a of the limiter rope 18 and on the right strand 18b of the limiter 18 each half the weight G / 2 of the weight 21 acts on the linkage 22 via the corresponding lever arm. This counteracts a vectorially opposing opposing force G / 2 in both the left strand 18a and in the right strand 18b of the limiter rope 18. Furthermore, a cable weight G _s attributable to this strand acts on both the left strand 18 a and the right strand 18 _{b of} the limiter rope 18. The governor rope 18 is pulled in this case to the left over the upper guide roller 19. The right-hand force on the fixed upper guide roller 19 is given by the resultant force S ₁ , which is composed of the cable weight G _s and the force G / 2. On the left strand 18a of the governor rope acts a correspondingly larger force S ₂ , which is increased by the friction on the groove of the upper guide roller 19 accordingly. As a triggering force for the triggering of the braking device 6 is a vectorially downwardly acting force F ₁ exploitable, resulting from the difference between the force S ₂ and acting in the opposite direction rope weight G _s and the force G / 2.

Fig. 11 illustrates the conditions when braking the car 1 in the upward direction. In this case, the governor rope 18 is pulled to the right over the fixed, upper deflection roller 19. Accordingly, the right-hand force S _{1 is} greater than the left-side force S ₂ on the upper guide roller 19. As a result, therefore, results in a vectorially upward force F ₂ on the left strand 18a of the Begrenzerseils 18, which is used as a triggering force for the braking device 6 ,

The force acting on the lower pulley 20 weight G and the ratio between the forces S ₁ and S ₂ determining geometry of the groove of the upper guide roller 19 must be dimensioned so that when braking the car 1 in the upward direction, the available release force F _2nd is still sufficient to safely trigger the braking device 6. Inevitably, this results in a slowing down of the car 1 down a much larger release force F ₁ , as Fig. 10 illustrates.

$$S_2=S_1•e^{f\left(\mu \right)•a}$$

$$S_1=G_s+\frac{G}{2}$$

For the same result also leads a calculation of the triggering force F for the case of the deceleration of the car down or up. In the case of the slowing down of the car 1 down can be assumed from the following equations. $${\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="imgf0001.png"\; state="\{\{state\}\}">S</figure-callout>}}_2=G_s+\frac{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="imgf0001.png"\; state="\{\{state\}\}">G</figure-callout>}}{2}+F_1$$

$${\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="imgf0001.png"\; state="\{\{state\}\}">S</figure-callout>}}_2=S_1•e^{f\left(\mu \right)•a}$$

$$S_1=G_s+\frac{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="imgf0001.png"\; state="\{\{state\}\}">G</figure-callout>}}{2}$$

$$S_1=S_2•e^{f\left(\mu \right)•a}$$

$$S_1=G_s+\frac{G}{2}$$

In the case of slowing down the catcher 1 in the upward direction, the following equations apply: $${\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="imgf0001.png"\; state="\{\{state\}\}">S</figure-callout>}}_2=G_s+\frac{G}{2}-F_2$$

$$S_1={\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="imgf0001.png"\; state="\{\{state\}\}">S</figure-callout>}}_2•e^{f\left(\mu \right)•a}$$

$$S_1=G_s+\frac{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="imgf0001.png"\; state="\{\{state\}\}">G</figure-callout>}}{2}$$

S₁

rechtsseitige Zugkraft an der oberen Umlenkrolle 19

S₂

linksseitige Zugkraft an der Umlenkrolle 19

G_s

halbes Gewicht des Begrenzerseiles 18

G

auf die untere Umlenkrolle 20 einwirkende Spann kraft, verursacht durch das Gewicht 21

F_1/2

an dem Auslöser 7 angreifende Kraft

α

Umschlingungswinkel an der oberen Umlenkrolle 19 (α = 180°)

f(µ)

Reibwert in Abhängigkeit von der Rillenform der oberen Umlenkrolle 19

In this system of equations mean

S ₁

right-hand pulling force on the upper deflection roller 19

S ₂

left-side tensile force on the deflection roller 19th

G _s

half the weight of the limiter rope 18

G

acting on the lower pulley 20 clamping force caused by the weight 21st

F _1/2

on the trigger 7 attacking force

α

Wrap angle at the upper deflection roller 19 (α = 180 °)

f (μ)

Friction value as a function of the groove shape of the upper guide roller 19th

On the basis of the equations (4), (5) and (6) given above, on the basis of a conventional geometry for the groove on the upper deflection roller 19, the weight G of the weight 21 acting on the lower deflection roller 20 is calculated first by a predetermined amount To obtain triggering force in the upward direction F ₂ , and one sets the determined in this way required weight G in the equations (1), (2) and (3), we obtain the downward effective release force F ₁ as a function of the above effective release force F ₂ . Requires a safe release of the braking device 6, for example, a release force of 400N and dimensioned the weight 21 so that these 400N are achieved in the upward direction, we obtain for the release force in the downward direction F _1, a force of about 1550N, ie a force almost 4x is as large as the upward triggering force F ₂ . This means that both the governor rope 18, as well as the trigger 7 and the associated braking device 6 have to withstand this very high release force in the downward direction, which makes special design requirements and thereby increases the manufacturing cost of the braking device 6 and the trigger 7. In addition, a standardized braking device 6 with associated trigger 7, which is officially approved in its design for the braking of the car in the downward direction, due to the excessive release force in the upward direction can not be readily used.

To solve this problem, the present invention proposes to connect the trigger 7 of the braking device 6 with the limiter rope 18 for limiting the force transmitted to the trigger 7 via a slip connection 30. The governor rope 18 slips on the slip connection 30 by, when the limiter rope 18 on the trigger 7, a force is transmitted, which is considerably greater than the triggering force required for triggering the braking device 6. If the required release force is, for example, 400N, then the slip connection 30 can be adjusted so that it slips through, for example, 800N. This provides a sufficient safety margin from the required trigger force of 400N and limits the otherwise down tripping force from 1550N to said 800N.

An exemplary structural realization of this slip connection 30 is shown in FIGS. 2 to 9. In this case, Fig. 2 shows the items and their mounting position. Fig. 3, however, shows the fully assembled slip connection 30, which is preferably mounted below the cable connector 26 on the governor rope 18. The mounting position directly below the cable connector 26 has the advantage that when slipping the slip connection 30 on the governor rope 18 down an unlimited slide length is available.

In the illustrated embodiment, the slip connection 30 consists of a base plate 31, two clamping screws 33, two tension springs 34, two sleeve-shaped clamping stops 35 and mounting screws 36. Between the clamping screws 33 and the tension springs 34 first discs 37 are interposed, while between the mounting screws 36 and the Swivel lever 9 of the trigger 7 second discs 38 are interposed. On the base plate 31 is a groove 40 for guiding the Begrenzerseils 18. The groove 40 may of course alternatively be formed on the clamping plate 32 or both on the clamping plate 32 and on the base plate 31.

The embodiment of the slip connection 30 shown in FIGS. 2 and 3 will be described in detail below with reference to FIGS. 4 to 6. In this case, Fig. 4 shows a 5 shows a section along the line AA in FIG. 4 and FIG. 6 shows a section along the line BB in FIG. 4. Elements already described are provided with identical reference symbols in order to facilitate the assignment.

As can be seen from Fig. 5, the governor rope 18 is clamped between the base plate 31 and the clamping plate 32. A threaded shaft 50 of each clamping screw 33 is in each case screwed into a thread 51 of the base plate 31. By tightening the clamping screws 33 is an associated tension spring 34, which consists in the illustrated embodiment of a plurality of stacked plate springs 53, clamped between a screw head 52 of the associated clamping screw 33 and between the disc 37 and the clamping plate 32. The tension force exerted by the tension spring 34 depends on the pretension and thus on the depth of engagement of the threaded shaft 50 into the base plate 31. The depth of engagement of the clamping screw 33 is limited by the clamping stop 35. In the illustrated embodiment, the clamping stop 35 is formed in each case as a sleeve which surrounds the threaded shank 50 of the respective clamping screw 33. On the clamping plate 32, a bore 54 is provided for each clamping screw 33 and each clamping stop 35, through which both the threaded shank 50 of the clamping screw 33 and the sleeve-shaped clamping stop 35 engages. The sleeve-shaped clamping stop 35 is clamped between the screw head 52 and between the disc 37 and the surface 55 of the base plate 31.

In the illustrated embodiment, two clamping screws 33 are provided. Of course, in the context of the invention, only a single clamping screw 33 or three or more clamping screws 33 are used.

As can be seen from Fig. 6, in the embodiment, the clamping plate 32 threaded holes 56, in which the mounting screws 36 are screwed, so that the rocker arm 9 of the trigger 7 is connected to the clamping plate 32. Alternatively, it is of course also possible to connect the pivot lever 9 of the trigger 7 with the base plate 31.

Due to the defined bias of the tension springs 37, the force with which the governor rope 18 is clamped between the tension plate 32 and the base plate 31 is defined. By appropriate dimensioning of the length of the sleeve-shaped clamping stop 35, the bias of the tension springs 37 can be accurately and reproducibly metered. This allows an exact and reproducible determination of that force between the governor rope 18 and the trigger 7, when exceeding the limiter rope 18 slips on the slip connection 30.

The geometry of the groove 40 formed on the base plate 31 will be described below with reference to FIGS. 7, 8 and 9 in more detail. Fig. 7 shows a plan view of the base plate 31, Fig. 8 shows a side view of the base plate 31 shown in Fig. 7 and Fig. 9 shows a section along the line AA in Fig. 8. Already described elements are to facilitate the assignment with provided matching reference numerals.

From FIG. 4, the groove 40 extending in the longitudinal direction on the surface 55 of the base plate 31 can be seen, which respectively opens at the ends 60 and 61 of the base plate 31 in an opening region 62 or 63, which will be described in more detail. From Fig. 8, which shows a side view of the base plate 31 with a view of one of the two ends 60, the preferred triangular cross-sectional contour of the groove 40 can be seen. Furthermore, it can be seen that the groove 40 opens in the opening area 62 both in the direction of the surface 55 and transversely to the surface 55 of the base plate 31.

From the recognizable in Fig. 9 section along the line AA in Fig. 8, the preferred opening angle of 15 ° detect. The angle of attack of the two flanks of the triangular groove 40 is preferably about 90 °.

By the opening portions 62 and 63, an abrupt kinking of the Begrenzerseils 18 is avoided if the longitudinal axis 64 of the groove 40 is not exactly exactly parallel to the clamping direction of the governor rope 18.

Of course, as already mentioned, the groove 40 can alternatively or additionally also be provided on the clamping plate 32.

In the context of the invention, it is also conceivable that not only the upper guide roller 19 or the lower guide roller 20 is stopped in response of the speed limiter 27, but the Begrenzerseil 18 itself. For this purpose, the rollers 19 and 20 instead of deflection rollers, for example, as a synchronized Aufauf and Abwinkelrollen be formed. By inventively created flexible slip connection 30 between the trigger 7 and the Begrenzerseil 18 instead of the previously used rigid compound connected via the trigger 7 and the braking device 6 to the car 1 slide connection 30 on the stationary governor rope 18 both in the upward direction and in the downward direction slip after exceeding the triggering force required for the triggering of the braking device 6. This increases the flexibility of the construction of the securing device.

Claims (10)

1. Device for preventing uncontrolled acceleration of an elevator car (1) of an elevator installation with a governor rope (18) that passes over pulleys (19, 20) in the direction of movement of the elevator car (1), a braking device (6) that is connected to the elevator car (1) and which is connected via a tripper (7) to the governor rope (18) and which brakes the elevator car (1) in both the downward and upward direction when the governor rope (18) transmits a specified tripping force to the tripper (7), and an overspeed governor (27) connected to at least one of the pulleys (19), or directly to the governor rope (18), that brings at least one of the pulleys (19), or the governor rope (18), to rest when the speed of travel of the elevator car (1) exceeds a specified limit speed either in the downward direction or in the upward direction,
   characterized in that
   to limit the force transmitted to the tripper (7), the tripper (7) of the braking device (6) is connected to the governor rope (18) via a slipping connection (30) in such manner that when a force that is significantly greater than the tripping force needed to trip the braking device (6) is transmitted from the governor rope (18) to the tripper (7) of the braking device (18) the governor rope (18) slips on the slipping connection (30).
2. Device according to Claim 1,
   characterized in that
   the pulleys are return pulleys (19, 20), the governor rope (18) is passed endlessly over the return pulleys (19, 20), and one of the return pulleys (19) is brought to rest by the overspeed governor (27), the governor rope (18) being pulled over the stationary return pulley (19) by the elevator car (1) when the overspeed governor (27) is actuated.
3. Device according to Claim 2,
   characterized in that
   an upper return pulley (19) is brought to rest by the overspeed governor (27), and a weight (21) for tensioning the governor rope (18) acts on a lower return pulley (20), a greater brake force being exerted on the governor rope (18) when braking the elevator car (1) in downward direction than when braking the elevator car (1) in upward direction, and
   in that the slipping connection (30) is set so that the governor rope (18) slips on the slipping connection (30) only when the elevator car (1) is braked in downward direction.
4. Device according to Claim 3,
   characterized in that
   the free ends (24, 25) of the governor rope (18) are connected together on a rope connector (26), and the slipping connection (30) is arranged below the rope connector (26).
5. Device according to one of Claims 1 to 4,
   characterized in that
   the slipping connection (30) has a base plate (31) and a pressure plate (32) that is pretensioned against the base plate (31) with a specified compression force, the governor rope (18) running between the base plate (31) and the tension plate (32).
6. Device according to Claim 5,
   characterized in that
   the tension plate (32) has at least one drilled hole (54) through each of which a tension screw (33) passes and protrudes, the tension screw (33) being screwable into a thread (51) in the base plate (31), and the depth to which it can be screwed being limited by a tightening stop (35).
7. Device according to Claim 6,
   characterized in that
   between a projection, in particular a screw head (52), of the tension screw (33) facing away from the base plate (31), and the tension plate (32), a compression spring (34) is clamped.
8. Device according to Claim 7,
   characterized in that
   the compression spring (34) comprises several cup springs (53) arranged in a stack.
9. Device according to one of Claims 5 to 8,
   characterized in that
   the governor rope (18) is guided in a groove (40) in a surface (55) of the base plate (31) and/or of the tension plate (32).
10. Device according to Claim 9,
    characterized in that
    the groove (40) has a triangular cross section.

Images