EP1512656A1

EP1512656A1 - Counterweight

Info

Publication number: EP1512656A1
Application number: EP02738691A
Authority: EP
Inventors: Kazumasa c/o Mitsubishi Denki K.K. ITO
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2002-06-13
Filing date: 2002-06-13
Publication date: 2005-03-09
Anticipated expiration: 2022-06-13
Also published as: JPWO2003106321A1; DE60235727D1; KR20040021694A; CN1549789A; CN1285500C; KR100569799B1; EP1512656B1; WO2003106321A1; EP1512656A4

Abstract

In a counterweight (10) which rises and lowers in balance with a car rising and lowering in an elevator system (100), the counterweight (10) has an upper counterweight (30) and a lower counterweight (32), and the upper counterweight (30) and the lower counterweight (32) can be separated from each other. Also, when the counterweight (10) is separated, the upper counterweight (30) has an upper brake device (36) for stopping the upper counterweight (30), and the lower counterweight (32) has a lower brake device (38) for stopping the lower counterweight (32).

Description

Technical Field

The present invention relates to a counterweight. More particularly, the present invention relates to a counterweight for elevator system, which rises and lowers by being connected to a car rising and lowering in an elevator system.

Background Art

Figure 7 is a schematic view showing an outline of a traction type elevator system 200.
As shown in Figure 7, the elevator system 200 has an elevator shaft 2. The upper part of the elevator shaft 2 is closed by a machine room floor 4, and a machine room 6 is provided above the floor 4.
In the elevator shaft 2, a car 8 and a counterweight 10 are hung.
In the machine room 6 is provided a hoisting machine 24, and a rope 26 is wound around the hoisting machine 24. Both ends of the rope 26 hang from the machine room 4 into the elevator shaft 2. One end of the rope 26 is fixed to the car 8, and hangs the car 8 in the elevator shaft 2. The other end thereof is fixed to the counterweight 10, and hangs the counterweight 10 in the elevator shaft 2.
In the elevator system 200 constructed as described above, the car 8 and the counterweight 10 are raised and lowered in the elevator shaft 2 by the movement of rope caused by the rotation of the hoisting machine 24.
In such a traction type elevator system 200, the car 8 and the counterweight 10 rise and lower with a some degree of weight balance in a state in which they are fixed to both ends of the rope 26. Also, the weight of the counterweight 10 is usually set at a half of the rated load of the car 8 considering the system efficiency.
Therefore, for example, in the case where the load in the car 8 is lower than a half of the rated load, if the movement of the car 8 and the counterweight 10 becomes incapable of being controlled because of a failure etc. of the elevator system 200 during the time when the car 8 rises, it is thought that the rising speed of the car 8 increases and the car 8 rises at a speed higher than the rated speed because the car 8 is lighter than the counterweight 10. In this case, the counterweight 10 moves downward at a speed higher than the rated speed.
As a precaution against such an emergency case, for example, a buffer 60 is provided in the elevator system 200 at the lower part of the elevator shaft 2 on the counterweight 10 side. By causing the lowering counterweight 10 to collide with the buffer 60, a shock can be absorbed to some degree, so that the shock can be eased as compared with the case where the counterweight 10 collides directly with the bottom of the elevator shaft 2. However, even if the shock can be eased to some degree, when the counterweight 10 lowers in the elevator shaft 2 at a speed higher than the rated speed, it collides with the buffer 60 at a speed higher than the rated speed. In such a case, a great shock is given to the counterweight 10 as well as the car 8.
Also, as another precaution against the emergency case, for example, an emergency stopper is installed under the car 8 or the counterweight 10, and a speed governor is provided in the machine room 6. Thereby, rapid movement of the car 8 at a speed higher than the rated speed is detected, and if the car 8 moves at a speed higher than the rated speed, a brake is applied to stop the car 8. Further, as another precaution, a rope brake such as to hold a main rope directly is sometimes provided. In operating the elevator system, various safety precautions are taken.
However, in order to install the above-described safety device for emergency stop, the elevator system requires some degree of space. In installing the elevator system, however, space saving is often demanded strongly. Therefore, a safety device requiring a space for installation is not necessarily suitable. Also, when a device for directly holding the main rope to stop the elevator is used, the main rope may be worn early. Further, the safety devices of these types have complicated construction, so that a malfunction is liable to occur. Also, these devices are high in cost in most cases. In addition, when these devices are used, the braking force depends on the frictional force, so that the deceleration force during braking fluctuates greatly. Also, when the operation speed is high, the braking distance increases, and hence a shoe is worn, which may make braking operation impossible.
In the device in accordance with the invention proposed in Japanese Patent Laid-Open No. 5-193860, there is a structural time lag before the equipment is operated and a braking force is generated, so that the car may be accelerated due to the delayed time.

Disclosure of the Invention

Accordingly, the present invention proposes a counterweight for elevator system, which has been improved to solve the above problems and to easily prevent the moving speed of a car from becoming a speed higher than the rated speed.
Therefore, the present invention provides a counterweight which rises and lowers by being connected to a car rising and lowering in an elevator system, characterized in that the counterweight has an upper counterweight and a lower counterweight, and the upper counterweight and the lower counterweight can be separated from each other. According to this construction, the balance between the car and the counterweight can be adjusted by separating a part of the counterweight. Therefore, the rising and lowering speed can be alleviated, and hence a collision of the car or the counterweight with the bottom of an elevator shaft can be prevented, or the shock of collision can be eased.
Also, in the counterweight in accordance with the present invention, when the counterweight is separated, the upper counterweight has an upper brake device for stopping the upper counterweight, and the lower counterweight has a lower brake device for stopping the lower counterweight. According to this construction, the upper counterweight and the lower counterweight that rise or lower are separated from each other and can be stopped individually. Therefore, the car can be stopped more easily, and the safety of elevator system can be ensured.
Also, the counterweight for elevator system in accordance with the present invention has a resetting means for connecting the upper counterweight and the lower counterweight to each other when the upper counterweight and the lower counterweight have been separated from each other. Thereby, even after the upper counterweight and the lower counterweight have been separated from each other, the connection can be resetting easily.

Brief Descriptions of Drawings

Figure 1 is a schematic view of an elevator system in accordance with an embodiment of the present invention.
Figure 2 is a schematic view for illustrating a construction of a counterweight of the elevator system in accordance with an embodiment of the present invention.
Figure 3 is a schematic view of the resetting plate of the elevator system in accordance with an embodiment of the present invention.
Figure 4 is a schematic view showing a state in which the emergency brake is operated in the elevator system in accordance with an embodiment of the present invention.
Figure 5 is a schematic view showing the state of the upper counterweight at the time when the emergency brake is operated in the elevator system in accordance with an embodiment of the present invention.
Figure 6 is a schematic view showing the state of the lower counterweight 32 at the time when the emergency brake is operated in the elevator system in accordance with an embodiment of the present invention
Figure 7 is a schematic view showing an outline of a traction type elevator system.

Best Mode for Carrying Out the Invention

An embodiment of the present invention will now be described with reference to the accompanying drawings. In the figures, same reference numerals are applied to the same or corresponding elements, and the explanation of such elements is simplified or omitted.
Figure 1 is a schematic view of an elevator system 100 in accordance with an embodiment of the present invention. Also, Figure 2 is a schematic view for illustrating a construction of a counterweight 10 in the elevator system 100, in which Figure 2A being a front view and Figure 2B being a side view. Figure 2 shows an emergency brake arranged on the right-hand side in Figure 1 and a surrounding portion thereof.
As shown in Figure 1, the elevator system 100 has an elevator shaft 2. The upper part of the elevator shaft 2 is closed by a machine room floor 4, and a machine room 6 is provided above the floor 4.
In the elevator shaft 2, a car 8 and a counterweight 10 are hung. The counterweight 10 is designed so as to have a weight that is a half of the rated load of the car 8. On the car 8 side of the elevator shaft 2 are provided guide rails 12, and the car 8 is connected to the guide rails 12 so as to be movable vertically. On the counterweight 10 side thereof are provided guide rails 14, and the counterweight 10 is connected to the guide rails 14 so as to be movable vertically. At the upper part and the lower part of the guide rail 14, there are provided resetting plates 16 and 18, respectively.
The machine room floor 4 is formed with two rope penetrating holes 20 and 22. Also, a hoisting machine 24 is provided in the machine room 6.
A rope 26 is wound around the hoisting machine 24. One end of the rope 26 hangs from the machine room 6 into the elevator shaft 2 through the rope penetrating hole 20 formed in the machine room floor 4, and is fixed to the car 8 to hang the car 8 in the elevator shaft 2. The other end of the rope 26 hangs from the machine room 6 into the elevator shaft 2 through the rope passage 22 formed in the machine room floor 4, and is fixed to the counterweight 10 to hang the counterweight 10 in the elevator shaft 2.
In the elevator system 100 constructed as described above, by the rotation of the hoisting machine 24, the rope 26 is moved according to the direction of rotation. Thereby, the car 8 and the counterweight 10 that are fixed to both ends of the rope 26 are moved in the elevator shaft 2 along the guide rails 12 and 14.
Referring to Figures 1 and 2, the counterweight 10 has an upper counterweight 30 and a lower counterweight 32. The lower counterweight 32 has a slightly lighter weight than the unmanned weight of the car 8. Also, the weight of the upper counterweight 30 is set so that the weight of the whole of the counterweight 10 is a half of the rated load of the car 8 in a state where it is connected to the lower counterweight 32. Between the upper counterweight 30 and the lower counterweight 32 is provided an emergency brake. The upper counterweight 30 and the lower counterweight 32 are connected to the emergency brake. The rope 26 penetrates the upper counterweight 30 and is fixed to the upper part of the lower counterweight 32 only.
As shown in Figure 2, the emergency brake includes a brake central portion 34, an upper brake element 36, and a lower brake element 38.
The brake central portion 34 has a solenoid coil 40. The solenoid coil 40 is connected to a current source so that a current flows as necessary. In the center of the solenoid coil 40 is provided a plunger 42.
The upper brake element 36 is installed and fixed in the upper counterweight 30. The upper brake element 36 has a connecting rod 44. The connecting rod 44 has a through hole, and the plunger 42 of the brake central portion 34 passes through the through hole. By this construction, the brake central portion 34 is connected to the upper brake element 36, and hence the brake central portion 34 is connected to the upper counterweight 30.
Around the connecting rod 44 is wound an operating elastic member 46. The operating elastic member 46 is a spring-shaped elastic member formed by a strong wire. At one end of the connecting rod 44 is provided a roller 48. The roller 48 is a columnar member having a circular shape when viewed from the side. Also, the upper brake element 36 has a wedge-shaped groove 50 formed above the roller 48. The groove 50 has a tapered shape such that the distance to the guide rail 14 decreases upward when viewed from the side.
The lower brake element 38 is installed and fixed in the lower counterweight 32. The lower brake element 38 has a connecting rod 52. The connecting rod 52 has a through hole, and the plunger 42 of the brake central portion 34 passes through the through hole. By this construction, the brake central portion 34 is connected to the lower brake element 38, and hence the brake central portion 34 is connected to the lower counterweight 32.
Around the connecting rod 52 is wound an operating elastic member 54. The operating elastic member 54 is a spring-shaped elastic member formed by a strong wire. At one end of the connecting rod 52 is provided a roller 56. The roller 56 is a columnar member having a circular shape when viewed from the side. Also, the upper brake element 38 has a wedge-shaped groove 58 formed below the roller 56. The groove 58 has a tapered shape such that the distance to the guide rail 14 decreases downward when viewed from the side.
Figure 3 is a schematic view of the resetting plate. Figure 3A shows the resetting plate 16, and Figure 3B shows the resetting plate 18.
As shown in Figure 3, when viewed from the side, the upper resetting plate 16 has a downward tapered shape, and the lower resetting plate 18 inversely has an upward tapered shape.
Figure 4 is a schematic view showing a state in which the emergency brake is operated in the elevator system 100. Also, Figure 5 is a schematic view showing the state of the upper counterweight 30 at the time when the emergency brake is operated, and Figure 6 is a schematic view showing the state of the lower counterweight 32 at the time when the emergency brake is operated. Figures 5 and 6 each show the emergency brake arranged on the right-hand side in Figure 4 and a portion around the emergency brake. Figures 5A and 6A are front views, and Figures 5B and 6B are side views.
Next, the operation of the emergency brake will be described with reference to Figures 4 to 6.
As described above, the weight of the counterweight 10 is set so as to be a half of the rated load of the car 8. Therefore, for example, in the case where the hoisting machine 24 becomes uncontrollable due to a failure of the hoisting machine 24, breakage of a shaft, etc. during the time when the car 8 rises in a state such that the load in the car 8 is lower than a half load, that is, the counterweight 10 is heavier than the car 8, the rising speed of the car 8 increases, and the car 8 rises at a speed higher than the rated speed. Herein, the operation of the emergency brake in the case where the car 8 rises at an abnormal speed higher than the rated speed will be described.
First, when the car 8 rises at an abnormal speed higher than the rated speed, the counterweight 10 lowers at the same speed. At this time, in the elevator system 100, the abnormality is detected, and a current flows in the solenoid coil 40 from a source current. When the current flows in the solenoid coil 40, the plunger 42 moves in the inside direction when viewed from the front, and the plunger 42 is pulled out of the through holes in the connecting rods 44 and 52. Thereby, the upper brake element 36 and the lower brake element 38 are disconnected from each other. Therefore, as shown in Figure 4, the upper counterweight 30 is separated from the lower counterweight 32. At this time, the brake central portion 34 moves together with the lower brake element 38.
As shown in Figure 5, when the plunger 42 is pulled out of the connecting rod 44 of the upper brake element 36, the roller 48 is pushed upward by an elastic force of the operating elastic member 46 provided around the connecting rod 44. The roller 48 is pressed against the guide rail 14 as it moves upward along the wedge-shaped groove 50.
When the upper counterweight 30 continues lowering, the roller 48 is subjected to the upward elastic force of the operating elastic member 46 and an upward frictional force generated between the roller 48 and the guide rail 14, so that the roller 48 is further pushed upward. Thereby, the roller 48 is gradually fitted and pressed between the wedge-shaped groove 50 having a tapered shape such that the distance to the guide rail 14 decreases upward and the guide rail 14. When the roller 48 is fitted in the groove 50 completely, the upper brake element 36 is fixed to the guide rail 14, so that the upper counterweight 30 stops at an upper portion of the elevator shaft 2.
On the other hand, as shown in Figure 6, when the plunger 42 is pulled out of the connecting rod 52 of the lower brake element 38, the roller 56 is pushed downward by an elastic force of the operating elastic member 54 provided around the connecting rod 52. The roller 56 is pressed against the guide rail 14 as it moves downward slightly along the wedge-shaped groove 58. At this time, since the lower brake element 38 lowers, a frictional force generated between the roller 56 and the guide rail 14 is an upward force as in the case of the roller 48 of the upper brake element 36. However, the groove 58 of the lower brake element 38 has a tapered shape such that the distance to the guide rail 14 decreases downward contrary to the groove 50 of the upper brake element 36. Therefore, the roller 56 is not fitted in the groove 50 completely during lowering.
Therefore, the lower counterweight 32 continues lowering in a state in which the lower counterweight 32 and the car 8 are connected to each other by the rope 26. However, at this time, since the car 8 is heavier than the lower counterweight 32, the lower counterweight 32 stops lowering after lowering to some degree, and inversely the lower counterweight 32 begins rising by being pulled by the car 8. At this time, the frictional force generated between the roller 56 and the guide rail 14 becomes a downward force, so that the roller 56 is pushed downward by this downward frictional force and the downward elastic force applied by the operating elastic member 54. Therefore, the roller 56 is gradually fitted in the groove 58 and is pressed between the groove 58 and the guide rail 14. When the roller 56 fits in the groove 58 completely, the lower brake element 38 is fixed to the guide rail 14. Thereby, the lower counterweight 32 is stopped in an intermediate portion of the elevator shaft 2, whereby the car 8 is also stopped.
Next, the case where the upper and lower counterweights 30 and 32 that have been separated from each other are resetting will be described. In this case, first, the lower counterweight 32 is pushed down to a position at which the lower resetting plate 18 is provided by moving the elevator system 100 manually. Thereupon, an upward tapered portion of the resetting plate 18 automatically pushes up the roller 56 and removes it from the groove 58, so that the roller 56 is pushed back to the original position at which the lower counterweight 32 is connected to the upper counterweight 30. Thereby, the plunger 42 can be reconnected to the connecting rod 52 automatically.
Thereafter, the lower counterweight 32 is pushed up in this state together with the lower brake element 38 to the position at which the upper counterweight 30 stops, and successively the upper counterweight 30, i.e., the upper brake element 38 is pushed up together with the lower counterweight 32 to the position at which the upper resetting plate 16 is installed. Thereupon, a downward tapered portion of the resetting plate 16 automatically pushes down the roller 48 and removes it from the groove 50, so that the roller 28 is pushed back to the original position at which the upper counterweight 30 is connected to the lower counterweight 32. Thereby, the plunger 42 is automatically connected to the connecting rod 52, by which the upper counterweight 30 can be connected to the lower counterweight 32.
In the above description, the case where the car 8 rises at a speed higher than the rated speed in the state in which the load in the car 8 is lower than a half load in the counterweight 10 has been explained. However, even in the case where the car 8 lowers at a speed higher than the rated speed due to any failure or the like occurring in the state in which the load in the car 8 is higher than a half load, that is, the counterweight 10 is lighter than the car 8, measures can be taken as described below by this elevator system.
In this case, when an abnormal speed is detected in the state in which the counterweight 10 rises, a current flows in the solenoid 40 as in the above-described case where the counterweight 10 lowers, and hence the plunger 42 is moved to separate the upper counterweight 30 from the lower counterweight 32. At this time, since the upper counterweight 30 is not connected to the rope 26, it stops rising immediately and begins lowering. Thereafter, the roller 48 fits in the groove 50, and thereby the upper counterweight 30 is stopped as in the above-described case where a failure occurs during the time when the counterweight 10 lowers.
On the otherhand, the lower counterweight 32 continues rising while being pulled by the car 8, by which the roller 56 is pushed downward by a downward elastic force of the operating elastic member 54 and a downward frictional force generated between the roller 56 and the guide rail 14. Therefore, the roller 56 fits in the groove 58, whereby the lower counterweight 32 is stopped.
As described above, according to this emergency brake, since the unmanned load of the car 8 is set so as to be heavier than the weight of the lower counterweight 32, even if a failure occurs either when the load of the car 8 is lower than a half load or when the load thereof is higher than a half load, or either during the time when the car 8 rises or during the time when it lowers, the lower counterweight 32 is raised finally by being pulled to the car 8 side by the disconnection of the counterweight 10. Therefore, the roller 56 fits in the groove 58 during rising, whereby the lower counterweight 32 is stopped.
On the other hand, since the separated upper counterweight 30 is not connected to the car 8, it lowers finally in either case where the car 8 is rising or lowering. Therefore, during lowering, the roller 48 fits in the groove 50, whereby the upper counterweight 30 is stopped.
Thus, even if the car 8 begins rising or lowering at a speed higher than the rated speed due to a failure of the hoisting machine 24 etc. when the weights of the car 8 and the counterweight 10 are imbalanced, the car 8 can be stopped by a simple device. Also, according to this device, the counterweight 10 can be separated easily by a simple mechanism, so that a machine malfunction is less liable to occur, and thus a highly reliable emergency brake can be installed.
In this elevator system 100, even if the upper counterweight 30 and the lower counterweight 32 are separated from each other, they can be connected easily by manually moving the elevator system 100. Therefore, a simple emergency brake can be installed without a need for preparing a complicated device.
Also, according to this elevator system 100, since the emergency brake is installed in the counterweight 10, a special installation space is unnecessary, so that space saving can be achieved.
In the present invention, the shape, construction, and the like of the elevator system and the members thereof are not limited to those described in the above embodiment in the scope of the present invention.
In this embodiment, the plunger 42 and the connecting rods 44 and 52 are used as means for disconnecting the upper counterweight 30 and the lower counterweight 32 from each other. However, the present invention is not limited to the construction explained in this embodiment. The upper counterweight 30 and the lower counterweight 32 may be disconnected from each other, for example, by a device that is electrically controlled from the outside.
Also, in this embodiment, a wedge effect using the rollers 48 and 56 and the grooves 50 and 58 is utilized as means for stopping the upper counterweight 30 and the lower counterweight 32. However, the present invention is not limited to the construction explained in this embodiment.
Also, in this embodiment, a description has been given of the elevator system in which the counterweight 10 is separated into two, and the emergency brake for completely stopping the upper and lower counterweights 30 and 32 is provided. However, the present invention is not limited to the elevator system having the emergency brake. Even in the case where the emergency brake is not provided, if the counterweight 10 can be separated into two, by setting the car 8 and the upper and lower counterweights so as to be imbalanced, the rising and lowering speed higher than the rated speed can be alleviated. Also, if such a counterweight and a buffer etc. having been used conventionally are used combinedly, a further safety precaution can be taken.
In the present invention, upper and lower brake devices mean means for stopping the upper and lower counterweights, respectively. For example, they correspond to the upper and lower brake elements 36 and 38 in this embodiment, respectively.
Also, in the present invention, upper and lower rotating bodies correspond to, for example, the rollers 48 and 56 in this embodiment, respectively. Upper and lower elastic members correspond to, for example, the operating elastic members 46 and 54, respectively. Upper and lower grooves correspond to, for example, the grooves 50 and 58, respectively.
Also, in the present invention, connecting means indicates means for connecting the upper and lower counterweights to each other, and corresponds to, for example, the brake central portion 34 in this embodiment. A connecting portion corresponds to, for example, the connecting rods 44 and 52 in this embodiment. A penetrating shaft corresponds to the plunger 42.
Also, in the present invention, a control unit corresponds to, for example, a portion including the solenoid coil 40 in this embodiment.
Also, in the present invention, resetting means indicates means for reconnecting the upper counterweight and the lower counterweight to each other when the upper counterweight and the lower counterweight have been disconnected from each other, and corresponds to, for example, the resetting plates 16 and 18 in this embodiment.

Industrial Applicability

As described above, according to the present invention, the counterweight for elevator system can be separated into an upper part and a lower part. Therefore, during the time when the elevator system rises or lowers, by separating the counterweight as necessary, the balance between the car and the counterweight can be adjusted to decrease the rising and lowering speed.
Also, in the present invention, if the upper and lower brake devices are provided in the separated counterweights, the elevator system can be stopped by a simple device, and safety in elevator operation can be ensured.
Also, in the present invention, if the resetting means is provided, the counterweights can easily be resetting to the original connected state after they have been separated. Therefore, the operation of the elevator system can be resetting rapidly without preparing complicated equipment, so that improvement in service and reduction in cost can be achieved.

Claims

A counterweight which rises and lowers by being connected to a car rising and lowering in an elevator system, characterized in that
said counterweight comprises an upper counterweight and a lower counterweight; and
said upper counterweight and said lower counterweight can be separated from each other.
The counterweight according to claim 1, characterized in that
said upper counterweight is provided with an upper brake device for stopping said upper counterweight when said counterweight is separated; and
said lower counterweight is providedwith a lower brake device for stopping said lower counterweight when said counterweight is separated.
The counterweight according to claim 2, characterized in that
said counterweight rises and lowers along a guide rail provided in an elevator shaft of the elevator system;
said upper brake device comprises an upper rotating body installed so as to be movable in the advance direction when said counterweight is separated,
an upper elastic member for pushing said upper rotating body upward when said counterweight is separated, and
an upper groove provided above said upper rotating body so as to have a tapered shape such that the distance to said guide rail decreases upward; and
when said upper counterweight moves downward, said upper rotating body is pushed up and fitted between said upper groove and said guide rail to stop said upper counterweight.
The counterweight according to claim 2 or 3, characterized in that
said counterweight rises and lowers along a guide rail provided in an elevator shaft of the elevator system;
said lower brake device comprises a lower rotating body installed so as to be movable in the advance direction when said counterweight is separated,
a lower elastic member for pushing said lower rotating body downward when said counterweight is separated, and
a lower groove provided below said lower rotating body so as to have a tapered shape such that the distance to said guide rail decreases downward; and
when said lower counterweight moves upward, said lower rotating body is pushed down and fitted between said lower groove and said guide rail to stop said lower counterweight.
The counterweight for elevator system according to any one of claims 1 to 4, characterized in that
said counterweight has connecting means for connecting said upper counterweight and said lower counterweight to each other;
said upper counterweight and said lower counterweight each have a connecting portion formed with a through hole;
said connecting means has a penetrating shaft capable of passing through said through holes; and
said upper counterweight and said lower counterweight are connected to each other by causing said penetrating shaft to pass through said through holes.
The counterweight according to claim 5, characterized in that
said connecting means is connected to a control unit for sensing the rising or lowering movement of said car and/or said counterweight when said car and/or said counterweight rises or lowers at an abnormal speed higher than a predetermined speed; and
said penetrating shaft is removed from said through holes in said connecting portions by a signal sent from said control unit to separate said upper counterweight from said lower counterweight.
The counterweight according to any one of claims 1 to 6, characterized in that said counterweight is provided with a resetting means for connecting said upper counterweight and said lower counterweight to each other when said upper counterweight and said lower counterweight have been separated from each other.