Tubular linear motor driven elevator

Abstract: A linear motor driven elevator comprises: a cab (1) capable of upward and downward movement; a linear motor (8) comprising a movable element (9) and a stationary element (10); a counterweight (15) attached to the movable element such that the movable element is disposed thereon out of register with the center of gravity of the counterweight; and a rope (4) connecting the cab (1) and the counterweight (15) above the center of gravity of the counterweight.

Description: This invention relates to a tubular linear motor driven elevator. A conventional linear motor type elevator is shown in Fig. 4. Cab 101 is powered upwardly and downwardly in a building by means of a linear motor 102. The linear motor 102 comprises a movable element 103 having an axial hole through which a rod-shaped stationary element 104 passes. A frame 107 houses weights 105 and 106 at both sides of the movable element 103. The frame, the weights and the movable element form a counterweight for balancing the weight of the cab 101. Rope pairs 108a, 108b and 109a, 109b, attach at one end thereof to each side of the stationary element at the upper end of the frame, pass over sheaves 110a, 110b, 111a, 111b and attach at a second end thereof to the top of the cab. If ropes 108a, 108b, 109a, 109b are somehow severed, two buffers 112, 113 are provided at both sides at the lower end side of the movable element 104 to prevent the frame, movable element and weights from colliding with the floor of the building. It is an object of the present invention to provide a linear motor driven elevator in which the number of ropes, sheaves, buffers and the like are minimized. According to the invention, there is provided a linear motor driven elevator comprising: a cab, a counterweight, a linear motor comprising a movable element and a stationary element, said movable element being attached to said counterweight out of register with the center of gravity of said counterweight, and a rope attached at a first end thereof to said cab and at a second end thereof to a top portion of said counterweight at a position vertically above the center of gravity of said counterweight. By moving the linear motor out of register with the center of gravity of the counterweight, the ropes can be attached to the counterweight above the center of gravity of the counterweight. As a result, the number of ropes, sheaves, and buffers may be minimized. The ropes may be reduced to one set of three ropes as opposed to two sets of two ropes. Further, one set of ropes requires only two sheaves as opposed to four in the prior art. Finally, a single buffer may be provided at the center of gravity of the counterweight, without interfering with the stationary element, so that the pair of buffers required by the prior art are no longer necessary. These and other objects, features, and advantages of the present invention will become more apparent in light of the following detailed description of an embodiment thereof, given by way of example only, and with reference to the accompanying drawings, wherein: Figure 1 is a perspective view showing an example of the linear motor driven elevator of the present invention; Figure 2 is a front view of the movable element and the counterweight; Figure 3 is a cross-sectional view taken along the line A-A in Figure 2; Figure 4 is a perspective view of a linear motor driven elevator of the prior art. Referring to Figs. 1-3, an embodiment of a linear motor driven elevator according to the present invention is shown. Referring to Fig. 1, cab 1 is disposed in a building in a manner capable of upward and downward movement. Guide rails extend at both sides of the cab 1, as is known in the art, to guide the cab upwardly and downwardly via sliding roller members 3 attached to the cab. One set of three ropes 4a, 4b, 4c is attached to the center of an upper wall of the cab 1, guided by sheave 6 rotating about a first support shaft 5, guided by sheave 7 rotating about a second support shaft, and secured to a counterweight 15 as will be discussed infra. The linear motor 8 comprises a movable element 9 having an axial hole through which a stationary element 10 passes. The stationary element 10 extends the length of the building, has a top portion which is fixed to a support 11 via connector 10a, and has a bottom portion which is fixed to a stationary member 12 via support 10b. Referring to Fig. 2, the counterweight 15 comprises frame 14, weights 16 and 17, and movable element 9. The frame 14 is guided upwardly and downwardly along rails 21, 22 by sliding roller members 23, 24. Movable element 9 is attached to the left side of the frame. Weights 17 are placed on the right side of the counterweight between upper and lower plate members 14a, 14b and between column members 14c which are provided between the upper and lower plate members 14a, 14b, to balance the weight of the movable element. Filler weights 16 are added as necessary so that the entire weight of the counterweight balances the weight of the cab 1. The weight of the counterweight 15 including the movable element 9 is about 1.5 times the weight of the cab 1. As described above, the movable element 9 is located at one side of rather than the center of the frame 14, so that ropes 4a, 4b, 4c may be connected above the center of gravity of the counterweight 15 (via hitch plate 19) without interfering with the stationary element 10. An electrical junction box 20 is provided under the upper plate member 14a. Travelling cable 31 supplies electricity for movable element 9 via junction box 20 as is known in the art. A buffer plate 26 is attached to the lower plate member 14b of the frame by means of pairs of shafts 25. The buffer plate 26 has a hydraulic buffer device 27 under which is provided a buffer 28 (see Fig. 1). Buffer 28 is positioned under the center of gravity of the buffer plate 26 without interfering with the stationary element 10. As described above, the buffer 28 can be provided under the center position of the buffer plate 26, so that a pair of buffers is unnecessary. Each pair of support shafts 25 is provided with a braking device 29 or 30. As shown in Fig. 3, at both sides of the stationary element 10 a pair of brake arms 32a, 32b are supported by the support shafts 25 in a freely rotating manner. An electromagnetic brake 33 is disposed between the proximal ends of the brake arms 32a, 32b. The electromagnetic brake 33 comprises an armature 33a, a brake coil 33b for attracting the armature, and a brake spring 34 disposed between the armature 33a and the brake coil 33b. The distal ends of the brake arms 32a, 32b clamp a rail 21 via linings. A spring 35 is provided between the distal ends. The armature 33a of the electromagnetic brake is attracted by the brake coil 33 during application of current. The attraction dissipates if a power outage occurs and the brake arms 32a, 32b clamp the rail 21 by means of the force of the brake spring 34 to stop the movable element 9 and the cab 1. Although the invention has been shown and described with respect to an embodiment thereof, it should be understood by those of ordinary skill in the art, that various omissions, changes and additions in the form and detail thereof may be made without departing from the scope of the invention as claimed.

Claims: A linear motor driven elevator comprising: a cab (1), a counterweight (15), a linear motor (8) comprising a movable element (9) and a stationary element (10), said movable element being attached to said counterweight out of register with the center of gravity of said counterweight, and a rope (4) attached at a first end thereof to said cab (1) and at a second end thereof to a top portion (14a) of said counterweight (15) at a position vertically above the center of gravity of said counterweight. The linear motor driven elevator of claim 1 further comprising: a buffer (28) disposed beneath and in register with said center of gravity of said counterweight. The linear motor driven elevator of claim 1 or 2 wherein the linear motor (8) comprises a tubular movable element having an axial opening therein and the stationary element (10) extends through said opening. The linear motor driven elevator of claim 1, 2 or 3 further comprising: a braking surface, and a brake (29, 30) disposed upon said counterweight (15) for cooperating with said braking surface to stop motion of said counterweight (15), said brake (29, 30) having a first arm (32a) for contacting said surface and a second arm (32b) for contacting said surface, said first arm (32a) being disposed on a first side of said stationary element (10) and said second arm (32b) being disposed on a second side of said stationary element.

Inventors: NAKANISHI YOSHINORI, NAKANISHI, YOSHINORI
Applicants: OTIS ELEVATOR CO, OTIS ELEVATOR COMPANY
Application year: 1992
Main classification: B66B11
IPC codes: B66B11, H02K5, B66B7, B66B9