EP1813566B1

EP1813566B1 - Safety device for elevator

Info

Publication number: EP1813566B1
Application number: EP04822652.6A
Authority: EP
Inventors: Tsunehiro Mitsubishi Denki KK HIGASHINAKA
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2004-11-16
Filing date: 2004-11-16
Publication date: 2013-09-18
Anticipated expiration: 2024-11-16
Also published as: EP1813566A4; CN1886320B; CN1886320A; JPWO2006054328A1; JP4672656B2; EP1813566A1; WO2006054328A1

Description

Technical Field

This invention relates to a safety device for an elevator, which forcibly stops a car of an elevator when the travel speed of the car of the elevator exceeds a predetermined value.

Background Art

An elevator apparatus has, as a safety device, a car safety device which forcibly stops a car in an emergency stop manner when the travel speed of the car exceeds a predetermined value. Figure 4 schematically shows the construction of an elevator apparatus equipped with a conventional car safety device. Referring to Figure 4, a car 13 and a counterweight 14 of an elevator are suspended by a main rope 16 wrapped around a driving sheave 15 of a traction machine in a well bucket manner, and are vertically moved opposite to each other through a shaft by being linked to the rotation of the driving sheave 15. The car 13 and the counterweight 14 are guided in their travel directions by guide rails 1 (only partially shown in the figure) vertically installed in the shaft. An endless governor rope 19 having its portion connected to the car 13 is wrapped around a main sheave 17 of a governor provided on a shaft top portion and a governor rope tension sheave 18 provided on a shaft pit portion. The main sheave 17 of the governor rotates by being linked to the movement of the governor rope 19, as the governor rope 19 is moved by being linked to the vertical movement of the car 13. That is, the governor detects the travel speed of the car 13 on the basis of the rotational speed of the main sheave 17.
If a rotational speed abnormality, a reduction in traction or the like of the driving sheave 15 of the traction machine occurs, and if the descending speed of the car 13 exceeds a certain prescribed value, the governor detects a car 13 speed abnormality and forcibly stops the car 13. More specifically, a car 13 speed abnormality is detected from the rotational speed of the main sheave 17 of the governor when the rotational speed exceeds a predetermined value. When a car 13 speed abnormality is detected, a seizing means (not shown) provided on the governor seizes the moving governor rope 19 to forcibly restrain the governor rope 19. A car safety device 2 provided on the car 13 is operated by the governor rope 19 restraining operation through a safety link 20 connected between the car safety device 2 and the governor rope 19, thereby forcibly stopping the car 13. In ordinary cases, the car safety devices are placed so as to face the guide rails 1, and generate a braking force by causing brake elements to bite into the guide rails 1 with a wedge effect.
A conventional safety device of the above-described construction has been disclosed (see, for example, patent document 1) which operates a pair of car safety devices provided in correspondence with guide rails for guiding a vertically moving member formed of a car or a counterweight, by directly pushing upward lower surfaces of wedges of the car safety devices by means of push-up levers of safety links fixed to the vertically moving member and a governor rope.
Patent document 1: Japanese Patent Laid-Open No. 2001-80840
A ropeless governor system for governing the speed of an elevator car in the event of an overspeed condition is for example disclosed in patent document 2. An actuator for a safety device is positioned in close proximity to an elevator rail and if activated provides a dragging force against the rail. This activates an elevator safety braking system, which is coupled to the ropeless governor and initiates the braking operation.
Patent document 2: US 6,161,653

Disclosure of the Invention

Problem to be Solved by the Invention

Conventional safety devices, such as the safety device described in patent document 1, having a governor rope, a safety link and other members, has a large time lag from detection of a car speed abnormality to actual stoppage of the car caused by the operation of car safety devices. That is, because of various delays in operation, e.g., a delay in operation of the seizing means of the governor which occurs as a time period from detection of a car speed abnormality to stoppage of the governor rope, a delay in operation which occurs due to elastic deformation of the governor rope as a time period from stoppage of the governor rope to a start of operation of the safety link, and a delay in operation which occurs due to play between connections as a time period from a start of operation of the safety link to a start of operation of the car safety devices, acceleration of the car is continued for a certain time period after the moment at which the descending speed of the car exceeds a certain prescribed value, resulting an increase in car stopping distance.
This invention has been achieved to solve this problem, and an object of this invention is to provide a safety device for an elevator capable of reducing the time period required to stop the car after detection of car speed abnormality.

Means for Solving the Problems

A safety device for an elevator relater to the present invention having a car moving vertically in an elevator shaft, a guide rail vertically installed in the shaft to guide the car, and a car speed detection means for detecting a speed abnormality of the car, in which the car is stopped when a speed abnormality of the car is detected by the car speed detection means, the safety device comprising a guide surface provided on the car and placed so as to be distanced away from one side surface of the guide rail along a downward direction, a brake element provided between the guide surface and the one side surface of the guide rail, and an attraction portion provided on the brake element and attracted to the guide rail when a speed abnormality of the car is detected by the car speed detection means, wherein, when the attraction portion is attracted to the guide rail, the brake element is stopped from descending and is guided by the descending guide surface to produce a braking force between the brake element and the one side surface of the guide rail.

Effect of the Invention

This invention provides a safety device for an elevator having a car moving vertically in an elevator shaft, a guide rail vertically installed in the shaft to guide the car, and a car speed detection means for detecting a speed abnormality of the car, in which the car is stopped when a speed abnormality of the car is detected by the car speed detection means, the safety device including a guide surface provided on the car and placed so as to be distanced away from one side surface of the guide rail along a downward direction, a brake element provided between the guide surface and the one side surface of the guide rail, and an attraction portion provided on the brake element and attracted to the guide rail when a speed abnormality of the car is detected by the car speed detection means, wherein, when the attraction portion is attracted to the guide rail, the brake element is stopped from descending and is guided by the descending guide surface to produce a braking force between the brake element and the one side surface of the guide rail. This arrangement makes it possible to reduce the time period required for stoppage of the car after detection of a speed abnormality of the car.

Brief Description of the Drawings

Figure 1 is a front view of a safety device for an elevator in Embodiment 1 of this invention.
Figure 2 is a side view of an essential portion of the safety device for the elevator in Embodiment 1 of this invention.
Figure 3 is a diagram for explaining the operation of the safety device for the elevator in Embodiment 1 of this invention.
Figure 4 is a constructional diagram of an elevator apparatus equipped with a conventional car safety device.

Description of Symbols

1 Guide rail, 1a Flange portion, 1b Head portion,
2 Car safety device, 3 Base, 4 First brake element,
4a Braking surface, 5 Guide portion, 5a Guide surface,
6 Second brake element, 6a Braking surface, 7 Attraction portion,
8 Guide, 9 Guide plate, 10 Guide portion, 10a Stopper,
11 Electromagnet, 11a Attraction surface, 12 Spring,
13 Car, 14 Counterweight, 15 Driving sheave,
16 Main rope, 17 Main sheave, 18 Governor rope tension sheave,
19 Governor rope, 20 Safety rink,

Best Mode for Carrying Out the Invention

This invention will be described in more detail with reference to the accompanying drawings. In the drawings, portions identical or corresponding to each other are indicated by the same reference numerals. Redundant portions of descriptions made below of such portions are suitably reduced or eliminated.

Embodiment 1

Figure 1 is a front view of a safety device for an elevator in Embodiment 1 of this invention. Referring to Figure 1, a car (not shown) which moves vertically in an elevator shaft is guided in its travel direction by engagement between guide rollers (not shown) or the like provided on upper and lower opposite end portions of the car and a pair of guide rails 1. The guide rails 1 have a generally T-shaped transverse section and are vertically installed in the shaft so that head portions 1b projecting from flange portions 1a face each other, with the car interposed therebetween. Also, car safety devices 2 are provided on lower portions of the car in correspondence with the guide rails 1. The car safety devices 2 respectively engage the guide rails 1 to stop the car in an emergency stop manner when the descending speed of the car exceeds a certain prescribed value. A car speed detection means for detection as to whether or not the car descending speed exceeds the certain prescribed value and an electric power control means for performing electric power control on electromagnets (to be described below) of the car safety devices 2 when the car speed detection means detects a value of the descending speed of the car in excess of the certain prescribed value are provided on the car or a shaft fixed member, although they are not shown in the drawings.
The above-described car safety device 2 has a base 3 provided on the car and placed in correspondence with the guide rail 1, a first brake element 4 provided on the base 3 and having a braking surface 4a facing one side surface of the head portion 1b of the guide rail 1 while being spaced apart from the same by a small gap therebetween, a guide portion 5 provided on the base 3 and having a guide surface 5a formed so as to be distanced away from the other side surface of the head portion 1b of the guide rail 1 along a downward direction, a second brake element 6 having a braking surface 6a provided between the guide surface 5a of the guide portion 5 and the other side surface of the head portion 1b of the guide rail 1 so as to be vertically slidable along the guide surface 5a, and facing the other side surface of the head portion 1b of the guide rail 1, and an attraction portion 7 provided on a lower portion of the second brake element 6 and having its portion attracted and fixed to the other side surface of the head portion 1b of the guide rail 1 under the control of the electric power control means when a car speed abnormality is detected by the car speed detection means.
The above-described guide portion 5 is constituted by a guide 8 provided on the base 3 and having the shape of a generally triangular prism with the above-mentioned guide surface 5a, and guide plates 9 obliquely provided respectively on the opposite sides of the guide surface 5a of the guide 8, and generally L-shaped. The guide plates 9 are formed so that turned portions placed so as to face each other on the head portion 1b side of the guide surface 5a of the guide 8 are generally parallel to the guide surface 5a while being distanced away from the other surface side of the head portion 1b of the guide rail 1 as the guide plates 9 go downward.
The second brake element 6 and the guide plates 9 are provided with a slide mechanism such that the second brake element 6 is slidable upward and downward along the turned portions of the guide plates 9. This slide mechanism may be of any construction. For example, a construction may be adopted in which a projection generally T-shaped in section is formed on the side of the second brake element 6 opposite from the head portion 1b and this projection engages with the turned portions of the guide rails 9.
The second brake element 6 slidable upward and downward on the guide plates 9 is placed at a lower position on the guide plates 9 due to its weight when no external force is applied. At this time, a predetermined gap is formed between the braking surface 6a of the second brake element 6 and the other side surface of the head portion 1b of the guide rail 1 facing each other, and the braking surface 6a does not contact the other side surface of the head portion 1b. When the second brake element 6 is moved from this state toward the tops of the guide plates 9, it moves gradually toward the head portion 1b while being guided by the slide mechanism provided between the second brake element 6 and the guide plates 9. That is, the braking surface 6a of the second brake element 6 and the other side surface of the head portion 1b are brought closer to each other and the gap formed therebetween is gradually reduced. When the second brake element 6 reaches a predetermined height, the side surface of the second brake element 6 opposite from the head portion 1b side and the guide surface 5a of the guide 8 engage with each other through a slide mechanism such as a roller guide (not shown). When the second brake element 6 reaches another predetermined height by being further moved upward, the distance between the braking surface 4a of the first brake element 4 and the braking surface 6a of the second brake element 6 becomes approximately equal to the width of the head portion 1b of the guide rail 1. The braking surface 4a and the braking surface 6a are thereby brought into contact with one side surface of the head portion 1b and the other side surface of the head portion 1b, respectively. The second brake element 6 is set so that the height of the braking surface 6a at the time of contact with the head portion 1b of the guide rail 1 is approximately equal to that of the braking surface 4a of the first brake element 4.
Figure 2 is a side view of an essential portion of the safety device for the elevator in Embodiment 1 of this invention, showing a construction of the second brake element 6 and the attraction portion 7 provided on a lower portion of the second brake element 6. Referring to Figures 1 and 2, the attraction portion 7 provided below the braking surface 6a of the second brake element 6 is constituted by a guide portion 10 fixed to a lower portion of the second brake element 6, an electromagnet 11 having a generally cylindrical shape, placed so that an attraction surface 11a provided as its one end surface faces the other side surface of the head portion 1b of the guide rail 1, and mounted horizontally slidably on the guide portion 10 so that the attraction surface 11a can be brought into contact and moved apart from the other side surface of the head portion 1b, and springs 12 urging the electromagnet 11 in a direction opposite to a direction toward the other side surface of the head portion 1b.
The slide mechanism provided between the guide portion 10 and the electromagnet 11 may be of any construction. For example, a construction such as shown in Figure 2 may be adopted in which a channel having a generally T-shaped cross section is horizontally formed in a lower portion in the guide portion 10, and a projection having a generally T-shaped cross section and fitting to the channel is provided on an upper portion of the electromagnet 11. The springs 12 are provided between an outer peripheral surface of the electromagnet 11 and a stopper 10a provided on the guide portion 10. The stopper 10a is placed on the side of the above-described slide mechanism opposite from the head portion 1b so as to face the other end surface of the electromagnet 11 to stop the electromagnet 11 urged by the springs 12. Therefore, a predetermined gap is formed between the attraction surface 11a of the electromagnet 11 and the other side surface of the head portion 1b when the second brake element 6 is placed at a lower position on the guide plates 9.
The operation of the safety device for the elevator according to this invention will now be described.
Figure 3 is a diagram for explaining the operation of the safety device for the elevator in Embodiment 1 of this invention. Referring to Figures 1 and 3, the travel speed of the car is detected by the car speed detection means at all times during normal operation of the elevator. Under this condition, as shown in Figure 1, the second brake element 6 is placed at the lower position on the guide plates 9 due to its weight. Also, a predetermined gap is formed between the attraction surface 11a of the electromagnet 11 and the other side surface of the head portion 1b of the guide rail 1. When the car speed detection means detects a value of the descending speed of the car in excess of the certain prescribed value, the electric power control means supplies power to the electromagnet 11 on the basis of the result of detection by the car speed detection means, thereby producing a magnetic force at the attraction surface 11a of the electromagnet 11. The urging force of the springs 12 provided between the stopper 10a and the electromagnet 11 is set so as to be smaller than the attraction force produced between the electromagnet 11 and the guide rail 1 in the state shown in Figure 1. Accordingly, the electromagnet 11 is horizontally moved to the head portion 1b side of the guide rail 1 against the urging force of the springs 12 by being supplied with electric power from the electric power control means to be attracted and fixed to the head portion 1b of the guide rail 1 at a point on the same. By attraction of the electromagnet 11 to the head portion 1b of the guide rail 1, the second brake element 6 descending together with the car is stopped from descending.
On the other hand, the car of the elevator continues descending even after the electromagnet 11 has been attracted and fixed to the head portion 1b of the guide rail 1. Therefore the second brake element 6 is guided by the descending guide surface 5a of the guide 8 while being pressed toward the head portion 1b to bring the second braking surface 6a into contact with the other side surface of the head portion 1b, so that the second brake element 6 is inserted like a wedge between the guide 8 and the head portion 1b of the guide rail 1, thereby producing a high braking force to forcibly stop the car.
According to Embodiment 1 of this invention, only the operation to supply electric power to electromagnet 11 and to thereby cause attraction of the electromagnet 11 to the guide rail 1 is required before braking force for stopping the car is exerted after detection of a car speed abnormality. Therefore the time period taken before actually stopping the car can be markedly reduced in comparison with the case of using the governor rope, the safety link and so on as in the conventional art. Also, simplification of structure and a reduction in cost can be achieved because the need for the safety link and so on is eliminated. Further, there is no need to consider the connection between the car safety device 2 and the safety link, so that restrictions on placement of the car safety device 2 are relaxed and the operability in installation and maintenance is improved.
While in Embodiment 1 of this invention electric power is supplied to the electromagnet 11 to enable the same to be attracted and fixed to the head portion 1b of the guide rail 1 when a car speed abnormality is detected by the car speed detection means, an arrangement may alternatively be used in which the attraction portion 7 is provided with a permanent magnet (not shown) placed so as to face the other side surface of the head portion 1b of the guide rail 1 and slidably mounted on the guide portion 10a and an electromagnet 11 placed so as to cancel out the magnetic force of the permanent magnet, and electric power to the electromagnet 11 is cut to enable the permanent magnet to be attracted and fixed to the other side surface of the head portion 1b of the guide rail 1 when a car speed abnormality is detected by the car speed detection means. That is, the electromagnet 11 and the permanent magnet are placed so that the magnetic forces of these magnets can be cancelled out when electric power is supplied to the electromagnet 11 during normal operation of the elevator. When a car speed abnormality is detected, electric power to the electromagnet 11 is cut to enable the permanent magnet to be attracted to the head portion 1b of the guide rail 1. If this arrangement is adopted, the car can be maintained in the stopped state when no electric power is supplied to the electromagnet 11 during power outage for example, thus further improving safety.
While Embodiment 1 of this invention has been described with respect to a case where the descending speed of the car exceeds a certain prescribed value, the same safety device may be provided below the counterweight to enable emergency stop of the car when the ascending speed of the car exceeds a certain prescribed value.
Also, only a permanent magnet may be used as the attraction portion 7 and may be enabled by an elastic member or the like to be attracted and fixed to the guide rail 1 when a car speed abnormality is detected by the car speed detection means. In such a case, a roller or the like capable of contacting the guide rail 1 may be used as a car speed detection means to produce a braking force only by mechanical operations without using any electrical operation.

Industrial Applicability

According to the safety device for the elevator of this invention, as described above, the time period from detection of a car speed abnormality to an actual emergency stop of the car can be remarkably reduced and, therefore, the distance through which the car moves after the occurrence of an excessive car speed can be remarkably reduced, thus making it possible to provide a safer elevator apparatus.

Claims

A safety device for an elevator having a car (13) moving vertically in an elevator shaft, a guide rail (1) vertically installed in the shaft to guide the car (13), and a car speed detection means for detecting a speed abnormality of the car (13), in which the car (13) is stopped when a speed abnormality of the car (13) is detected by the car speed detection means, the safety device comprising:
a guide surface (5a) provided on the car (13) and placed so as to be distanced away from one side surface of the guide rail (1) along a downward direction;

a brake element (6) provided between the guide surface (5a) and the one side surface of the guide rail (1); and characterised by

an attraction portion (7) provided on the brake element (6) and attracted to the guide rail (1) when a speed abnormality of the car (13) is detected by the car speed detection means;

the safety device also being characterized in that when the attraction portion (7) is attracted to the guide rail (1), the brake element (6) is stopped from descending, and is guided by the descending guide surface (5a) to produce a braking force between the brake element (6) and the one side surface of the guide rail (1).
A safety device for an elevator according to claim 1, further comprising:
electric power control means for performing electric power control on the basis of the result of detection by the car speed detection means;

wherein

the attraction portion (7) is attracted to the guide rail (1) by the electric power control performed by the electric power control means when a speed abnormality of the car (13) is detected by the car speed detection means
The safety device for an elevator according to claim 2, characterized in that the attraction portion (7) has an electromagnet (11) which is placed so as to face the guide rail (1), and which is attracted to the guide rail (1) by being supplied with electric power when a speed abnormality of the car (13) is detected by the car speed detection means.
The safety device for an elevator according to claim 2, characterized in that the attraction portion (7) has a permanent magnet placed so as to face the guide rail (1), and an electromagnet placed so as to cancel out the magnetic force of the permanent magnet, and electric power to the electromagnet is cut to cause the permanent magnet to be attracted to the guide rail (1) when a speed abnormality of the car (13) is detected by the car speed detection means.