Method for avoiding unwanted safety gear tripping in a safety stopping system of an elevator system, a safety stopping system, and an elevator system

Abstract

In an elevator system, so as to avoid unwanted safety gear tripping, the kinetic energy, which is caused by inertia of the overspeed governor rope to the lever arm, is dissipated by implementing fluid viscous damping to dampen the rotary movement of the spindle shaft to prevent unwanted safety gear tripping in the event when the upwards movement of the moving mass is decelerated by a machinery brake to perform a quick stop of the moving mass. The fluid viscous damping is effected by a viscous fluid damper which is arranged in the synchronization linkage mounted to the moving mass.

Claims

1. A method for avoiding unwanted safety gear tripping in a safety stopping system of an elevator system, the safety stopping system comprising: a machinery brake for decelerating a moving mass so as to perform a quick stop of the moving mass; a safety gear mounted to the moving mass; an overspeed governor; an overspeed governor rope connected to the moving mass of the elevator system; and a synchronization linkage mounted to the moving mass for tripping the safety gear, the synchronization linkage comprising a lever arm having a first end pivotally connected to the overspeed governor rope and a second end fixedly connected to a spindle shaft to which a safety gear tripping arm for tripping the safety gear is connected, said method comprising the steps of: dissipating kinetic energy caused by inertia of the overspeed governor rope to the lever arm by implementing fluid viscous damping to dampen a rotary movement of the spindle shaft to prevent unwanted safety gear tripping when the upwards movement of the moving mass is decelerated by the machinery brake to perform a quick stop of the moving mass; and performing the fluid viscous damping by a fluid viscous damper cylinder acting on an arm or a rod connected directly or indirectly to the spindle shaft.

2. The method according to claim 1, wherein the damping force is a non-linear function of velocity of a piston relative to a cylinder of the fluid viscous damper cylinder.

3. The method according to claim 2, wherein in velocities of the piston relative to the cylinder of the fluid viscous damper cylinder smaller than a predetermined velocity the damping force is arranged to increase more forcibly than in higher velocities.

4. The method according to claim 1, wherein the fluid viscous damper cylinder is an oil damper cylinder.

5. The method according to claim 4, wherein the damping force is a non-linear function of velocity of a piston relative to a cylinder of the fluid viscous damper cylinder.

6. The method according to claim 1, wherein the moving mass is an elevator car.

7. The method according to claim 1, wherein the moving mass is a counterweight.

8. An elevator system comprising: a moving mass guided by a pair of guide rails to be vertically movable in an elevator shaft; a suspension rope attached to the moving mass; a traction wheel over which the suspension rope is lead; a hoisting machine for driving the traction wheel to move the moving mass; and the safety stopping arrangement according to claim 7.

9. A safety stopping arrangement for an elevator system for stopping a movement of the moving mass, the safety stopping arrangement comprising: a machinery brake for decelerating a moving mass so as to perform a quick stop of the moving mass; a safety gear mounted to the moving mass; an overspeed governor; an overspeed governor rope attached to the moving mass of the elevator system; a synchronization linkage mounted to the moving mass for tripping the safety gear, the synchronization linkage comprising: a lever arm having a first end pivotally connected to the overspeed governor rope and a second end; a spindle shaft to which the second end of the lever arm is fixedly connected; and a safety gear tripping arm for tripping the safety gear, the safety gear tripping arm being fixedly connected to the spindle shaft; and a fluid viscous damper arranged to dissipate kinetic energy caused by inertia of the overspeed governor rope to the lever arm to dampen the rotary movement of the spindle shaft; wherein the fluid viscous damper is a fluid viscous damper cylinder acting on an arm or rod connected directly or indirectly to the spindle shaft.

10. The safety stopping arrangement according to claim 9, wherein the fluid viscous damper cylinder is an oil damper cylinder.

11. The safety stopping arrangement according to claim 9, wherein the damping force is a non-linear function of velocity of a piston relative to a cylinder of the fluid viscous damper cylinder.

12. The safety stopping arrangement according to claim 9, wherein the moving mass is an elevator car.

13. The safety stopping arrangement according to claim 9, wherein the moving mass is a counterweight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:

(2) FIG. 1 schematically shows an elevator system according to one embodiment of the invention,

(3) FIG. 2 shows a detail A from FIG. 1,

(4) FIG. 3 is an axonometric view of the safety stopping arrangement according to one embodiment of the invention, and

(5) FIG. 4 is a diagram showing schematically the damping force being a non-linear function of the velocity of the piston relative to the cylinder of the fluid viscous damper cylinder in accordance with one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(6) In the following, description will be made to embodiments of the present invention. It is to be understood, however, that the description is given by way of example only, and that the described embodiments are by no means to be understood as limiting the present invention thereto.

(7) In particular, different exemplifying embodiments will be described using, as an example of an elevator system to which the embodiments may be applied, an elevator system as depicted and explained in connection with FIGS. 1 to 3.

(8) It is to be noted that the following examples and embodiments are to be understood only as illustrative examples. Although the specification may refer to an, one, or some example(s) or embodiment(s) in several locations, this does not necessarily mean that each such reference is related to the same example(s) or embodiment(s), or that the feature only applies to a single example or embodiment. Single features of different embodiments may also be combined to provide other embodiments. Furthermore, terms like comprising and including should be understood as not limiting the described embodiments to consist of only those features that have been mentioned; such examples and embodiments may also contain features, structures, units, modules etc. that have not been specifically mentioned.

(9) The general elements and functions of described elevator systems, details of which also depend on the actual type of elevator system, are known to those skilled in the art, so that a detailed description thereof is omitted herein. However, it is to be noted that several additional devices and functions besides those described below in further detail may be employed in an elevator system.

(10) FIG. 1 shows an elevator system and FIGS. 2 and 3 show details of the same. The elevator system has an elevator car 2 and a counterweight 3, which are both acting as a moving mass and are connected to each other by suspension ropes 19. The suspension ropes 19 are going around a traction wheel 20 which is driven by a hoisting machine 21. A machinery brake 1 is arranged in connection with the hoisting machine for decelerating a moving mass 2, 3 so as to perform a quick stop of the moving mass. Because of the heavy mass hanging on both ends of the suspension ropes 19, the suspension ropes 19 do not slide on the traction wheel 20. When the traction wheel 20 is driven by the hoisting machine 21 and rotates, the elevator car 2 and the counterweight 3 move. The elevator car 2 and the counterweight 3 are guided by guide rails 16 and 17 which are mounted to the walls of the shaft 18 in which the elevator system 1 is provided.

(11) FIG. 1 further shows an overspeed governor system 15 for the elevator car 2 which comprises an overspeed governor rope 5 both ends of which are connected to the elevator car 2 (the moving mass). The governor rope 5 goes around a governor pulley 22 on the top side of the elevator system and goes around a tension weight pulley 23 connected to a tension weight 24 on the bottom side of the elevator system. The governor rope 5 is connected to the elevator car 2 via a lever arm 8 of a synchronization linkage 7 having tripping arms 12 for tripping a safety gear 4 against both guide rails 16 of the elevator car 2.

(12) FIG. 1 further shows an overspeed governor system 15 for the counterweight 3, which is similar to that explained for the elevator car 2. The overspeed governor system 15 for the counterweight 3 comprises an overspeed governor rope 6 both ends of which are connected to the counterweight 7 (the moving mass). The overspeed governor rope 6 goes around a governor pulley 22 on the top side of the elevator system and goes around a tension weight pulley 23 connected to a tension weight 24 on the bottom side of the elevator system. The governor rope 6 connected to the counterweight 7 via a lever arm 8 of a synchronization linkage 7 having tripping arms 12 for tripping a safety gear 4 against both guide rails of the counterweight 7.

(13) Referring to FIGS. 2 and 3, a safety stopping arrangement has a synchronization linkage 7 is mounted to the moving mass, such as the elevator car 2 or counterweight 3 for tripping the safety gear 4. In this example of FIGS. 2 and 3 the synchronization linkage 7 is explained in connection with the elevator car 2, but the counterweight 3 can be equipped with similar synchronization linkage 7 as shown in FIG. 1. The synchronization linkage 7 is arranged in the lower beam 25 of the sling 26 of the elevator car 2.

(14) The synchronization linkage 7 comprises a lever arm 8. The lever arm 8 has a first end 9 pivotally connected to the overspeed governor rope 5. A spindle shaft 11 is rotatably bearing-mounted to the lower beam 25. The second end 10 of the lever arm 8 is fixedly connected to the spindle shaft 11. A safety gear tripping arm 12 is also fixedly connected to the spindle shaft 11 so that turning of the lever arm 8 rotates the spindle shaft and turns the safety gear tripping arm 12. Another safety gear tripping arm 12 is arranged (on the right side of FIGS. 2 and 3) for tripping another safety gear 4 acting in co-operation with another guide rail 16. The synchronization linkage 7 comprises a connecting rod 27 which transmits the motion of the spindle shaft 11 to said another safety gear tripping arm 12. An extension spring 28 is arranged in the synchronization linkage 7 to oppose the tripping action. A viscous fluid damper cylinder 13 is arranged to dissipate kinetic energy caused by inertia of the overspeed governor rope 5 to the lever arm 8 to dampen the rotary movement of the spindle shaft 11. The fluid viscous damper dissipates energy by pushing fluid through an orifice, producing a damping pressure which creates a force. The fluid viscous damper cylinder acts on an auxiliary arm 14 which is also fixedly attached to the spindle shaft 11. In some other (not shown embodiments) the fluid viscous damper may arranged to act on any suitable moving member of the synchronization linkage 7, such as arm 14 or tripping arm 12 or connecting rod 27 connected directly or indirectly to the spindle shaft 11. In this example the fluid viscous damper cylinder 13 compresses when the inertia of the overspeed governor rope 5 urges the lever arm 8 to turn the spindle shaft 11 in a clockwise direction. In some other embodiment the fluid viscous damper cylinder 13 may be arranged to rebound in that situation.

(15) Preferably, the fluid viscous damper 13 is an oil damper cylinder.

(16) The fluid viscous damper cylinder 13 has at least two damping ratios depending on the velocity of the fluid viscous damper cylinder 13. The damping ratio of the fluid viscous damper cylinder may be adjustable.

(17) FIG. 4 shows an example of how the damping force of the fluid viscous cylinder 13 can be arranged to vary in function of the velocity of the piston relative to the cylinder of the fluid viscous damper cylinder. The horizontal axis of the diagram represents the compression (or rebound) velocity of the fluid viscous damper cylinder. The vertical axis of the diagram represents the damping force F. The damping force F increases as a function of the velocity v. In the shown example, the damping force is a non-linear function of velocity of a piston relative to a cylinder of the fluid viscous damper cylinder. In smaller velocities the damping force is arranged to increase more forcibly than in higher velocities where the damping force increase is lightened. For example, the damping force function F(v) may be parabolic.

(18) This ensures that the damping force will not be too high in a normal emergency stop situation wherein the overspeed governor system trips the safety gears, and this operation will not be substantially delayed due to the provision of the fluid viscous damping.

(19) Although the invention has been the described in conjunction with a certain type of the elevator system, it should be understood that the invention is not limited to any certain type. While the present inventions have been described in connection with a number of exemplary embodiments, and implementations, the present inventions are not so limited, but rather cover various modifications, and equivalent arrangements, which fall within the purview of prospective claims.