Constant deceleration progressive safety gear system

Abstract

A safety gear system for an elevator has a main static mass, an auxiliary static mass and a dynamically changing mass, wherein the dynamically changing mass changes in accordance with the travel of the main static mass. The safety gear system includes at least one first safety gear which is configured to brake the auxiliary static mass by a constant braking force, and at least one second safety gear which is configured to brake the main static mass and the dynamically changing mass by an adjustable brake force which is adjustable in accordance with the change of the dynamically changing mass.

Claims

1. A safety gear system for an elevator having a main static mass, an auxiliary static mass and a dynamically changing mass, the dynamically changing mass changing in accordance with the travel of the main static mass, wherein the safety gear system comprises: at least one first safety gear configured to brake the auxiliary static mass by a constant braking force; and at least one second safety gear configured to brake the main static mass and the dynamically changing mass by an adjustable brake force, the adjustable brake force being adjustable in accordance with the change of the dynamically changing mass, wherein: the first safety gear is mounted to the auxiliary static mass and the second safety gear is mounted to the main static mass, the auxiliary static mass is movably connected with the main static mass by a connecting rod, and the relative movement between the auxiliary static mass and the main static mass caused by the change of the dynamically changing mass causes the connecting rod to adjust the adjustable brake force.

2. The safety gear system according to claim 1, wherein: the second safety gear comprises a movable adjustment wedge configured to control the braking force of the second safety gear; and the relative movement between the auxiliary static mass and the main static mass is transferred from the connecting rod as a linear movement through at least one bar to the movable adjustment wedge.

3. The safety gear system according to claim 2, wherein: the dynamically changing mass is connected to a lower portion of the main static mass; and a suspension rope is connected to the upper portion of the main static mass.

4. The safety gear system according to claim 2, wherein: the adjustable brake force provided by the second safety gear is adjustable with respect to a reference brake force designed for applying a reference target deceleration to the main static mass and the dynamically changing mass; and the reference target deceleration is determined in a state in which the main static mass is at a mid-shaft position.

5. The safety gear system according to claim 2, wherein: the main static mass comprises the at least one bar, the at least one bar being a bending bar configured to apply the linear movement to the movable adjustment wedge in accordance with the bending of the bending bar; and the bending bar is connected to the auxiliary static mass by the connecting rod, the connecting rod being configured to apply a bending force to the bending bar in accordance with the relative movement between the auxiliary static mass and main static mass.

6. The safety gear system according to claim 5, wherein: the dynamically changing mass is connected to a lower portion of the main static mass; and a suspension rope is connected to the upper portion of the main static mass.

7. The safety gear system according to claim 5, wherein: the adjustable brake force provided by the second safety gear is adjustable with respect to a reference brake force designed for applying a reference target deceleration to the main static mass and the dynamically changing mass; and the reference target deceleration is determined in a state in which the main static mass is at a mid-shaft position.

8. The safety gear system according to claim 2, wherein: the main static mass comprises a spring and the at least one bar, the at least one bar being an adjustment bar connected to the spring, the adjustment bar is configured to apply the linear movement to the movable adjustment wedge in accordance with a deformation of the spring; and the spring is connected to the auxiliary static mass by the connecting rod, the connecting rod being configured to apply a spring force to the spring in accordance with relative movement between the auxiliary static mass and the main static mass.

9. The safety gear system according to claim 8, wherein: the dynamically changing mass is connected to a lower portion of the main static mass; and a suspension rope is connected to the upper portion of the main static mass.

10. The safety gear system according to claim 8, wherein: the adjustable brake force provided by the second safety gear is adjustable with respect to a reference brake force designed for applying a reference target deceleration to the main static mass and the dynamically changing mass; and the reference target deceleration is determined in a state in which the main static mass is at a mid-shaft position.

11. The safety gear system according to claim 1, wherein: the dynamically changing mass is connected to a lower portion of the main static mass; and a suspension rope is connected to the upper portion of the main static mass.

12. The safety gear system according to claim 11 wherein: the adjustable brake force provided by the second safety gear is adjustable with respect to a reference brake force designed for applying a reference target deceleration to the main static mass and the dynamically changing mass; and the reference target deceleration is determined in a state in which the main static mass is at a mid-shaft position.

13. The safety gear system according to claim 1, wherein: the adjustable brake force provided by the second safety gear is adjustable with respect to a reference brake force designed for applying a reference target deceleration to the main static mass and the dynamically changing mass; and the reference target deceleration is determined in a state in which the main static mass is at a mid-shaft position.

14. The safety gear system according to claim 13, wherein the constant brake force provided by the first safety gear is designed to apply a constant target deceleration which is equal to the reference target deceleration of the second safety gear.

15. The safety gear system according to claim 13, wherein the reference target deceleration is 0.6 g-force.

16. The safety gear system according to claim 1, wherein: the elevator has a counterweight comprising the main static mass and the auxiliary static mass; and the dynamically changing mass is a compensation rope connected to the counterweight.

17. The safety gear system according to claim 1, wherein: the main static mass is an elevator car of the elevator; and the dynamically changing mass is a compensation rope and/or a traveling cable connected to the elevator car.

18. A safety gear system for an elevator having a main static mass, an auxiliary static mass and a dynamically changing mass, the dynamically changing mass changing in accordance with the travel of the main static mass, wherein the safety gear system comprises: at least one first safety gear configured to brake the auxiliary static mass by a constant braking force; and at least one second safety gear configured to brake the main static mass and the dynamically changing mass by an adjustable brake force, the adjustable brake force being adjustable in accordance with the change of the dynamically changing mass, wherein: the first safety gear is mounted to the auxiliary static mass and the second safety gear is mounted to the main static mass, the auxiliary static mass is movably connected with the main static mass by a connecting rod, the second safety gear comprises a movable adjustment wedge configured to control the braking force of the second safety gear, the relative movement between the auxiliary static mass and the main static mass is transferred as a linear movement to the movable adjustment wedge, the main static mass comprises a bending bar connected to the connecting rod and configured to apply the linear movement to the movable adjustment wedge in accordance with the bending of the bending bar, and the bending bar is connected to the auxiliary static mass by the connecting rod that is configured to apply a bending force to the bending bar in accordance with the relative movement between the auxiliary static mass and main static mass to adjust the adjustable brake force, the relative movement being caused by a change of the dynamically changing mass.

Description

DESCRIPTION OF THE EMBODIMENTS

(1) These and other objects, features, details and advantages will become more fully apparent from the following detailed description of embodiments of the present invention which is to be taken in conjunction with the appended drawings, in which:

(2) FIG. 1 shows a general configuration of an elevator system.

(3) FIG. 2 shows a safety gear system according to an embodiment of the invention.

(4) FIG. 3 shows a safety gear acting as second safety gear in the sense of the present invention.

(5) FIG. 4 shows a safety gear system according to another embodiment.

(6) According to the embodiment shown in FIGS. 2 and 3, the principle of the invention is described on the counterweight side.

(7) Making reference to FIG. 1, an elevator system comprises a counterweight 101 to which an compensation rope 102 is connected at the bottom thereof.

(8) According to the present embodiment, the counterweight is divided into an auxiliary static mass 3 and a main static mass 13, as shown in FIG. 2. The main static mass 13 is connected to suspension ropes 1 on the upper portion thereof so as to be suspended from the hoisting machinery (not shown). A pair of first safety gears 8 is connected to the auxiliary static mass 3 and is configured to provide a constant brake force on a guide rail 7 upon activation of a synchronization mechanism 11. The synchronization mechanism 11 is activated by an overspeed governor rope 10 in a well-known manner.

(9) A pair of second safety gears 9 is connected to the main static mass 13 and is configured to provide an adjustable brake force on the guide rail 7 upon activation of a synchronization mechanism 12. The synchronization mechanism 12 is activated by an overspeed governor rope 10 in a well-known manner.

(10) The two pairs of safety gears 8, 9 are functionally interconnected such that the deceleration produced by the first pair of safety gears 8 is used to adjust a brake force provided by the pair of second safety gears 9.

(11) Now, a case is considered according to which the counterweight having the main static mass 13 and the auxiliary static mass 3 moves downward and is braked by the pairs of safety gears 8, 9. As the pair of safety gears 8 produces a constant braking force and the weight of the auxiliary static mass 3 to be braked remains constant, the produced deceleration remains constant (a=F/m). Now, if the auxiliary static mass 3, which is decelerated by the pair of first safety gears 8 starts to move away from the main static mass 13 of the counterweight, the braking force of the pair of adjustable safety gears 9 needs to be increased. Further, when the auxiliary static mass 3, which is decelerated by the pair of first safety gears 8 starts to move closer to the main static mass 13 of the counterweight, the braking force of the pair of adjustable safety gears 9 needs to be decreased.

(12) In the schematic presentation of FIG. 2, the overspeed governor rope 10 acts on the synchronization mechanism 11 of the auxiliary static mass 3 and thus on the pair of first safety gears 8. This auxiliary static mass 3 is supported by the main static mass 13 of the counterweight and can be considered as part of the counterweight mass. The suspension ropes 1 are attached to the main static mass 13 of the counterweight. As the overspeed governor rope 10 engages the pair of first safety gears 8, the auxiliary static mass 3 starts to decelerate independently of the main static mass 13 and the mass of the compensation ropes 2.

(13) The pair of adjustable safety gears 9 is engaged either directly by the overspeed governor rope 10 like the pair of first safety gears 8 or by separate means due to the increasing distance between the auxiliary static mass 3 and the main static mass 13. Regardless of the engagement method, the deceleration of the main static mass 13 caused by the second safety gears 9 is affected by the mass of the compensation ropes 2.

(14) It is now assumed that the auxiliary static mass 3 and the main static mass 13 are not connected to each other. Further, it is assumed that the pair of first safety gears 8, which provide a constant braking force, is factory adjusted to produce 0.6 g deceleration for the auxiliary static mass 3. Further, it is assumed that the pair of second safety gears 9, which provides an adjustable braking force, is factory adjusted to produce 0.6 g deceleration for the main static mass 13 and for half of the mass of compensation rope 2. It is noted that, when the counterweight is at a mid-shaft position, i.e. the position of the counterweight at the longitudinal midpoint of the elevator shaft (not shown in the figures), half of the compensation rope 2 is acting as a mass on the main static mass 13.

(15) Under these assumptions, the auxiliary static mass 3 and the main static mass 13 would start to move towards each other upon safety gear activation below the mid-shaft position. The reason is that below the mid-shaft position, the mass of the compensation rope 2 becomes smaller than that which was used, combined with the main static mass 13, for dimensioning the pair of second safety gears 9 to achieve the 0.6 g deceleration of the main static mass 13. At the same time, the braking force of the second safety gears 9 acting on the main static mass 13 remains the same. Thus, the main static mass 13 is decelerated to a larger extent than at the mid-shaft position while the deceleration of the auxiliary mass 3 remains the same.

(16) Further, the auxiliary static mass 3 and the main static mass 13 would start to divert away from each other above the mid-shaft position. The reason is that above the mid-shaft position, the mass of the compensation rope 2 becomes larger than that which was used, combined with the main static mass 13, for dimensioning the pair of second safety gears 9 to achieve the 0.6 g deceleration of the main static mass 13. At the same time, the braking force of the second safety gears 9 acting on the main static mass 13 remains the same. Thus, the main static mass 13 is decelerated to a smaller extent than at the mid-shaft position while the deceleration of the auxiliary mass 3 remains the same.

(17) According to the present invention, the auxiliary static mass 3 is supported by the main static mass 13 e.g. by means of a connection rod 4 and a bending bar 5, as depicted in FIGS. 2 and 4, by means of which the relative movement between the auxiliary static mass 3 and the main static mass 13 is utilized to adjust the braking force provided by the pair of second safety gears 9.

(18) As can be seen in FIG. 2, the bending bar 5 is supported by lower bearings 14 and by upper bearings 15. In a stationary situation, the bending bar 5 is bent to a certain extent due to the weight of the auxiliary static mass 3. In FIG. 2, the bending bar 5 is shown schematically and the bending thereof is not depicted. When the auxiliary static mass 3 and the main static mass 13 move towards each other, the connection rod 4 acts on the bending bar 5 in a manner to increase the bending of the bending bar 5. When the auxiliary static mass 3 and the main static mass 13 divert from each other, the connection rod 4 acts on the bending bar 5 in a manner to decrease the bending of the bending bar 5.

(19) The ends of the bending bar 5 act on respective movable adjusting wedges 6a within the safety gears 9. The movable adjusting wedges 6a interact with fixed adjusting wedges 6b of the second safety gears 9. That is, the movable adjusting wedges 6a have an inclined surface on the top side, and the fixed adjusting wedges 6b have an inclined counter surface on the bottom side. When the movable adjusting wedge 6a is pushed by the end of the bending bar 5, the braking force of the second safety gear 9 is increased. When the adjustable wedge 6b is pulled by the end of the bending 5, the braking force of the second safety gear 9 is decreased.

(20) As explained above, the bending bar is in a stationary situation bent by the weight of the auxiliary static mass 3. When the static masses 3 and 13 approach each other, the bending amount of the bending bar 5 increases with the result that the ends of the bending bar 5 pull the movable adjusting wedges 6a, thus decreasing the braking force of the second safety gears 9. In contrast, when the static masses 3 and 13 move away from each other, the bending amount of the bending bar 5 decreases with the result that the ends of the bending bar 5 push the movable adjusting wedges 6a, thus increasing the braking force of the second safety gears 9.

(21) Now, making reference to FIG. 3, the adjustment of the braking force of the second safety gears 9 is described.

(22) As can be seen in FIG. 3, the second safety gear 9 comprises a wedge chamber 19 for accommodating brake wedges 18 and counter wedges 17. Each brake wedge 18 comprises a guide groove (not shown) for guiding the brake wedge 18 with respect to guide pins (not shown) mounted to the wedge chamber 19. The upper ends of the brake wedges 18 are connected to associated actuation levers (not shown) which are actuated by the synchronization mechanism 12. In the front view of FIG. 3, the brake wedges 18 have a substantial triangular shape with an inner lateral side and an outer lateral side 18a. This inner lateral side is oriented substantially vertically and comprises a friction surface 20 acting on the guide rail 7 when the second safety gear 9 is activated. The outer lateral side of the brake wedge 18 is inclined with respect to the vertical direction. The outer lateral side 18a is inclined such that the upper end of the brake wedge 18 has a smaller width in the lateral direction than the lower end thereof.

(23) The counter wedges 17 have a substantially triangular shape when seen in the front view of FIG. 3. An inner lateral side 17a of the counter wedges 17 is substantially parallel to the outer lateral side 18a of the adjacent brake wedge 18. As a result, the brake wedge 18 and the counter wedge 17 can slide with respect to each other.

(24) The outer lateral sides 17b of the counter wedges 17 are inclined with respect to the vertical direction such that the lower end of the counter wedge 17 has a smaller width in the lateral direction than the upper end thereof. The counter wedge 17 can slide along a counter surface 19a of the wedge chamber 19 at the outer lateral side 17b.

(25) Compression springs 16 are connected to the upper ends of the counter wedges 17. The compression springs 16 are oriented such that their spring forces act in parallel to the outer lateral side 17b of the counter wedge 17 and the counter surface 19a of the wedge chamber 19.

(26) When the second safety gear 9 is activated by means of the actuation levers, the brake wedges 18 are pulled upwardly to a larger extent than the counter wedges 17 are pressed against the compression springs 16. Due to the inclined lateral sides of the wedges 17, 18, the brake wedges 18 are pressed inwardly such that the friction surfaces 20 apply a braking force to the elevator guide rail 7 due to which the main static mass is stopped.

(27) Further, as is shown in FIG. 3, adjustment wedges 6 are provided above the springs 16 and form a support for the force applied by the counter wedges 17 to the springs 16. When the counterweight is at the mid-shaft position, it is assumed that the bending bar 5 is bent in such a manner that the movable adjustment wedge 6a is neither pushed nor pulled and it is a neutral position. In this neutral position, the second safety gear 9 provides the factory adjusted braking force for a deceleration of 0.6 g.

(28) When the counterweight is above the mid-shaft position and the mass of the compensation ropes 2 becomes larger, the distance between the auxiliary static mass 3 and the main static mass 13 becomes larger with the result that the bending bar 5 is bent to a smaller extent. As a consequence, the movable adjusting wedges 6a are pushed by the ends of the bending bar 5 and, as a further consequence, the counter wedges 17 are pushed downwards. As the counter wedges 17 are pushed downwards when the brake wedges 18 are pulled upwards for braking, the braking wedges 18 are pressed more against the guide rail 7 such that the braking force is increased. As a result, the main static mass 13 can be braked to a larger extent such that the deceleration does not strongly decrease due to the increase of the mass of the compensation ropes 2.

(29) By contrast, when the counterweight is below the mid-shaft position and the mass of the compensation ropes 2 becomes smaller, the distance between the auxiliary static mass 3 and the main static mass 13 becomes smaller with the result that the bending bar 5 is bent to a larger extent. As a consequence, the movable adjusting wedges 6a are pulled by the ends of the bending bar 5 and, as a further consequence, the counter wedges 17 can move upwards. As the counter wedges 17 are moved upwards, the braking wedges 18 are pressed less against the guide rail 7 such that the braking force is decreased. As a result, the main static mass 13 will be braked to a smaller extent such that the deceleration does not strongly increase due to the decrease of the mass of the compensation ropes 2.

(30) In a preferable embodiment, the weight of the auxiliary static mass 3 is specified as 1000 kg, because experience shows that achieving constant braking force is easier when the weight of the auxiliary static mass 3 is sufficiently high. However, the weight can be substantially less, if the safety gear adjustment can be ensured.

(31) There are a number of methods of how to transfer the relative movement of the two masses 3, 13 to linear motion of the movable adjustment wedges instead of the bending bar given in the example.

(32) For example, in a further embodiment shown in FIG. 4, the bending bar 5 can be replaced by two bars 5a which are connected by a hinge 5b to which or close to which also the connection rod 4 is connected. Furthermore, a compression spring 5c is connected to the hinge 5b. In a further modification, the spring does not need to be a compression spring provided below the hinge 5b but can also be a tension spring provided above the hinge 5c. When the static masses 3 and 13 approach each other, the connection rod 4 acts against the spring 5c in such a manner that the hinge 5b is moved downward with respect to the main static mass 13. As a result, the wedges 6a are pulled. By contrast, when the static masses 3 and 13 are moved away from each other, the connection rod 4 acts on the spring 5c in such a manner that the hinge 5b is moved upward with respect to the main static mass 13. As a result, the wedges 6b are pushed.

(33) A similar system can also be applied on car side, although with some disadvantages. On counterweight side, the counterweight mass can be divided into the auxiliary static mass and the main static mass. Thus, no actual additional mass is needed. On car side, the simplest method is to have the auxiliary static mass as an additional mass, which affects the needed hoisting capacity. It is also conceivable to utilize the car or parts of the car sling as the auxiliary static mass.