TECHNICAL FIELD

[0001] The present invention pertains to an elevator device in which distances between multiple cars provided inside the same hoistway are regulated in order to achieve safe operations of the respective cars.

BACKGROUND OF THE INVENTION

[0002] Japanese Patent No. 3570427 describes a conventional elevator device having hoisting machines corresponding to the respective cars are provided with car-control mechanisms in order to detect the relative distances between adjoining cars, while detecting relative distances between respective adjoining cars in the vertical direction using laser sensors provided independently of the car-control mechanisms. The relative distances between the respective cars are independently detected using car-control mechanisms and the laser sensors in order to improve safety by preventing the respective cars from coming into contact with each other.

[0003] However, because the distances between the respective cars are detected using laser sensors, there are risks that the directions of the lasers become unstable when cars adjoined vertically oscillate, the lasers are blocked by dust floating inside the hoistway, and, particularly, in that relative distances between the respective cars become difficult to detect accurately when the cars are far apart from each other.

SUMMARY OF THE INVENTION

[0004] An exemplary embodiment of the invention includes an elevator device that includes a first car and a second car that are provided inside the same hoistway so as to move in the vertical direction independently of each other. A first control mechanism controls the relative ascending/descending speed and relative distance between the first and second cars through a first detection system and a second control mechanism that controls the relative ascending/descending speed and relative distance between the first and second cars through a second detection system. The first detection system is provided independently of the second detection system.

[0005] In an exemplary embodiment, the first detection system includes at least two encoders that detect ascending/descending speeds and positions of the respective cars. The first encoder is associated with the first car and the second encoder is associated with the second car.

[0006] In another exemplary embodiment, the second detection system includes at least two speed regulators that are provided with rotary shafts that rotate as the first and second cars ascend/descend so as to detect excessive speeds of the respective cars, each of the speed regulators include a speed-regulator encoder that detects the ascending/descending speeds and positions of the respective cars as the respective rotary shafts rotate.

[0007] According to a further exemplary embodiment of the invention, because the respective speed regulators are provided with speed-regulator encoders that detect the ascending/descending speeds and positions of the respective cars, the speed regulators remain fixed even when the respective cars oscillate during the ascent/descent, so that the relative ascending/descending speeds and relative distances between the respective adjoining cars can be detected accurately. In addition, the relative ascending/descending speeds and relative distances between the respective cars can be detected even when the relative vertical distances between adjoining cars increase, without being affected by the distances separating them from each other. Even in the case of the structure in that two cars are provided inside the same hoistway, the relative ascending/descending speeds and relative distances between the respective cars can be detected accurately without being affected by oscillations and distances between the cars.

[0008] Further embodiments of the invention include that the ascent/descent of the respective cars is stopped when at least the first car-control mechanism or the second car- control mechanism has determined that the relative distance between the respective cars is small with respect to the relative ascending/descending speed. [0009] Furthermore, because the relative ascending/descending speeds and relative vertical distances between the respective adjoining cars are detected separately by the independent first car-control mechanism and second car-control mechanism, the fact that the relative distance between the respective cars has become small with respect to the relative ascending/descending speed can be detected even more accurately. [0010] In addition, the speed-regulator encoders are capable of detecting the absolute values of the rotational angles of the rotary shafts.

[0011] According to an exemplary embodiment of the invention, because speed- regulator encoders capable of detecting the absolute values of the rotational angles are utilized, the relative distances between the respective cars can be found during the ascent/descent of the cars even in the event of a power failure, for example, so that there is no need for a backup power supply.

[0012] Moreover, because the second car-control mechanism is provided that can detect the relative ascending/descending speeds and relative distances accurately,

independently of the first car-control mechanism and without being affected by the conditions of the cars, safety can be further improved by preventing the respective cars from coming into contact with each other.

[0013] Further, because the second car-control mechanism is never affected by the conditions of the cars, safety can be further improved by preventing the first and second cars from coming into contact with each other.

[0014] In addition, because the relative ascending/descending speeds and relative distances between respective adjoining cars are detected separately using the first and second car-control mechanisms, safety can be further improved by preventing the respective cars from coming into contact with each other.

[0015] Also, no backup power supply is needed due to the use of speed-regulator encoders capable of detecting the absolute values of the rotational angles, so that an increase in cost due to the need for additional equipment can be avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram showing the overall structure of an elevator device equipped with 2 cars inside the same hoistway, in an embodiment pertaining to the present invention.

[0017] Figure 2 is a diagram showing a car-control mechanism for controlling the respective cars based on output signals from the respective encoders in Figure 1.

[0018] Figure 3 is a diagram showing the relative ascending/descending speed and relative distance between the respective cars in Figure 1.

DETAILED DESCRIPTION

[0019] As shown in Figure 1, the elevator device is housed in a single hoistway 1 that extends in the vertical direction, and in a machine room 2 that is provided above the hoistway 1.

[0020] Housed inside hoistway 1 are first car 3 that ascends/descends vertically along guiderails, not illustrated, second car 4 that ascends/descends vertically in the hoistway 1 while staying a prescribed distance below the first car 3, and first and second weights 7 and 8 that are connected to the respective cars 3 and 4 via first and second hoisting ropes

5 and 6 connected to the first and second cars 3 and 4.

[0021] The machine room 2 houses first and second hoisting machines 11 and 12 for raising/lowering first and second cars 3 and 4 via the first and second ropes 5 and 6, and first and second speed regulators 13 and 14 that detect the ascending/descending speeds of the first and second cars 3 and 4.

[0022] The first and second cars 3 and 4 are designed to be raised/lowered independently of each other by the first and second hoisting machines 11 and 12. [0023] Rotational forces are applied to the first and second hoisting machines 11 and 12 by driving motors, not illustrated, in order to raise/lower the first and second cars 3 and 4 and first and second weights 7 and 8 via the first and second hoisting ropes 5 and 6. [0024] The rotary shafts of the first and second hoisting machines 11 and 12 are provided with a first detection system, which includes first and second hoisting-machine encoders 15 and 16 that detect the ascending/descending speeds and positions of the first and second cars 3 and 4 along with the rotations of the rotary shafts. [0025] A second detection system includes the first and second speed regulators 13 and 14 that are linked to first and second cars 3 and 4 via first and second speed regulator ropes 17a and 17b that run across the speed regulators 13 and 14. As the cars 3 and 4 are raised/lowered, the speed regulator ropes 17a and 17b are also raised/lowered so as to rotate the rotary shafts of the respective speed regulators 13 and 14. Also, the rotary shafts of the first and second speed regulators 13 and 14 are provided with first and second speed-regulator encoders 18 and 19 that detect the ascending/descending speeds and positions of the first and second cars 3 and 4 when the rotary shafts rotate. [0026] In the event that the ascending/descending speeds of the first and second cars 3 and 4 become excessive, that is, when they exceed a specific speed, respective speed regulators 13 and 14 slow the first and second speed regulator ropes 17a and 17b in order to regulate the ascending/descending speeds of the respective cars 3 and 4, or emergency stopping of the respective cars 3 and 4 is performed.

[0027] Furthermore, door-opening/closing arms 25 for opening/closing doors 24 of the respective cars are provided at the front of the first and second cars 3 and 4. [0028] As shown in Figure 2, the first and second hoisting-machine encoders 15 and 16 transmit the respective ascending/descending speeds and positions that are detected for the first and second cars 3 and 4 as output signals to first and second car-control circuits 21 and 22. The ascending/descending speeds and positions of the respective cars 3 and 4 are regulated by the first and second car-control circuits 21 and 22, and the relative ascending/descending speed and the relative distance between the first and second cars 3 and 4 are detected as well. The first and second cars 3 and 4 and first and second car- control circuits 21 and 22 constitute what is called a first control circuit. [0029] The first and second speed-regulator encoder 18 and 19 transmit the respective ascending/descending speeds and positions that are detected for the first and second cars 3 and 4 as output signals to second control circuit 23 serving as a second car-control mechanism, and the relative ascending/descending speed and relative distance between

the first and second cars 3 and 4 are detected by the second control circuit 23 independently of the first and second car-control circuits 21 and 22.

[0030] In addition, the first and second speed-regulator encoders 18 and 19 can detect the absolute values of the rotational angles of the rotary shafts of first and second speed regulators 13 and 14, and they can detect the positions of first and second cars 3 and 4 accurately even when the detection of the positions of the first and second cars 3 and 4 is temporarily interrupted due to a power failure while the speed regulators 13 and 14 are operating.

[0031] The operation of the exemplary embodiment of the elevator device will be explained below.

[0032] As shown in Figure 1, the first and second cars 3 and 4 provided inside the same hoistway 1 are raised/lowered in the vertical direction independently of each other by the first and second hoisting machines 11 and 12 while at least a prescribed distance is maintained between the first and second cars 3 and 4.

[0033] Then, as shown in Figure 2, as the first and second cars 3 and 4 move, the first and second car-control circuits 21 and 22 and second control circuit 23 detect the relative ascending/descending speed and relative distance between the first and second cars 3 and

4 according to the signals output from first and second hoisting-machine encoders 15 and 16 and first and second regulator encoders 18 and 19.

[0034] Here, when a judgment is made by either the first and second car-control circuits 21 and 22 or second control circuit 23 that there is a possibility that the relative distance between the respective cars 3 and 4 may become small with respect to the relative ascending/descending speed while the first and second cars 3 and 4 are ascending/descending, and that first and second cars 3 and 4 may come into contact with each other, emergency stopping of the respective first and second cars 3 and 4 is perfoπned.

[0035] The relationship between the relative ascending/descending speed and the relative distance between first and second cars 3 and 4 in the event of emergency stopping will be described below.

[0036] For example, when the distance needed for an ascending/descending car to come to a stop when braking is applied is denoted as S (unit = m), the ascending/descending speed is denoted as V (unit = m/s), and the deceleration rate of braking is denoted as D (unit = m/s ² ), the following relationship holds.

5 = V ² /2D ... Equation (1)

[0037] As shown in Figure 3, when the first and second cars 3 and 4 are ascending/descending inside hoistway 1, assuming that the ascending/descending speed of first car 3 is Vl, the ascending/descending speed of second car 4 is V2, the height of first car 3 is Sl, and the height of second car 4 is S2, the relative ascending/descending speed between first and second cars 3 and 4 becomes Vl - V2, and the relative distance between first and second cars 3 and 4 becomes Sl - S2. Here, upward of speeds Vl and V2 are taken as positive.

[0038] In the Equation (1), when the relative speed Vl - V2 between first and second cars 3 and 4 is substituted as speed V, and the relative distance Sl - S2 between first and second cars 3 and 4 is substituted as traveling distance S, the distance needed for first and second cars 3 and 4 to come to a stop in an emergency stop, that is, relative distance Sl - S2, can be expressed as follows.

S 1 - S2 = (Vl - V2) ² /(2D) ... Equation (2)

[0039] When leeway distance Sa is included in the Equation (2), taking into consideration communication delays for first and second hoisting-machine encoders 15 and 16 and first and second speed-regulator encoders 18 and 19, as well as delays in the emergency stopping operation for the respective cars 3 and 4, emergency stopping is carried out for the first and second cars 3 and 4 according to the following condition when the relative distance Sl - S2 has become small with respect to the relative ascending/descending speed Vl - V2.

Sl - S2 < (Vl - V2) ² /(2D) + Sa ... Equation (3)

[0040] The first and second cars can be reliably prevented from coming into contact with each other by carrying out emergency stopping of first and second cars 3 and 4 when the Equation (3) holds.

[0041] In addition, even in the case of a structure that involves three or more cars installed inside the hoistway 1, the relative ascending/descending speeds and relative distances between adjoining cars can be detected by providing hoisting-machine encoders and speed-regulator encoders for them, provided that the cars have independent hoisting machines and speed regulators.

[0042] Furthermore, when the first and second speed-regulator encoders 18 and 19 are provided on speed regulators for regulating excessive ascending/descending speeds of the respective weights 7 and 8, like the first and second speed regulators 13 and 14 that detect

the ascending/descending speeds and positions of the first and second cars 3 and 4, for example, the relative ascending/descending speeds and the relative distances between respective adjoining cars 3 and 4 in the vertical direction can likewise be detected. [0043] Therefore, according to the present embodiment, because first and second regulators 13 and 14 are provided with first and second regulator encoders 18 and 19 in order to detect the relative ascending/descending speed and relative distance between the first and second cars 3 and 4, the relative ascending/descending speed and the relative distance between the respective cars 3 and 4 can be detected reliably without being affected by the conditions of the respective cars 3 and 4, so that safety can be further improved by preventing respective cars 3 and 4 from coming into contact with each other. [0044] In addition, because the first and second regulators 13 and 14 are provided with speed-regulator encoders 18 and 19 capable of detecting the absolute values of the rotational angles, there is no need for a backup power supply, so that an increase in cost due to a need for additional equipment can be avoided.

[0045] While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.