Abstract
A buffer device (121) for an elevator system (100), the buffer device (121) including a first contact structure (501) and a second contact structure (503). The first contact structure (501) includes a first contact surface (505), and the second contact structure (503) includes a second contact surface (507). The first contact surface (505) and the second contact surface (507) are arranged for contacting respective vertically offset surfaces of an elevator car (101) or counterweight (109).
Claims
1. An elevator system comprising: a hoistway (103); an elevator car (101) and/or a counterweight (109) arranged to move within the hoistway (103); a buffer device (121) including: a first contact structure (501) and a second contact structure (503); wherein the first contact structure (501) comprises a first contact surface (505); wherein the second contact structure (503) comprises a second contact surface (507); wherein the first contact surface (505) and the second contact surface (507) are arranged for contacting respective vertically offset surfaces of an elevator car (101) or counterweight (109); wherein the buffer device (121) is positioned at a bottom of the hoistway beneath the elevator car (101) and/or the counterweight (109); wherein the elevator car (101) and/or counterweight (109) comprises a first buffer strike surface (401) and a second buffer strike surface (403); wherein the first buffer strike surface (401) is arranged to contact the first contact surface (505) of the buffer device (121), and wherein the second buffer strike surface (403) is arranged to contact the second contact surface (507) of the buffer device (121); wherein the first contact structure (501) has a first contact area (505); wherein the second contact structure (503) has a second contact area (507); and wherein the ratio of the first contact area (505) to the second contact area (507) is between 0.5 and 1.0.
2. An elevator system comprising: a hoistway (103); an elevator car (101) and/or a counterweight (109) arranged to move within the hoistway (103); a buffer device (121) including: a first contact structure (501) and a second contact structure (503); wherein the first contact structure (501) comprises a first contact surface (505); wherein the second contact structure (503) comprises a second contact surface (507); wherein the first contact surface (505) and the second contact surface (507) are arranged for contacting respective vertically offset surfaces of an elevator car (101) or counterweight (109); wherein the buffer device (121) is positioned at a bottom of the hoistway beneath the elevator car (101) and/or the counterweight (109); wherein the elevator car (101) and/or counterweight (109) comprises a first buffer strike surface (401) and a second buffer strike surface (403); wherein the first buffer strike surface (401) is arranged to contact the first contact surface (505) of the buffer device (121), and wherein the second buffer strike surface (403) is arranged to contact the second contact surface (507) of the buffer device (121); wherein the first contact structure (501) and the second contact structure (503) are formed from the same material.
3. An elevator system comprising: a hoistway (103); an elevator car (101) and/or a counterweight (109) arranged to move within the hoistway (103); a buffer device (121) including: a first contact structure (501) and a second contact structure (503); wherein the first contact structure (501) comprises a first contact surface (505); wherein the second contact structure (503) comprises a second contact surface (507); wherein the first contact surface (505) and the second contact surface (507) are arranged for contacting respective vertically offset surfaces of an elevator car (101) or counterweight (109); wherein the buffer device (121) is positioned at a bottom of the hoistway beneath the elevator car (101) and/or the counterweight (109); wherein the elevator car (101) and/or counterweight (109) comprises a first buffer strike surface (401) and a second buffer strike surface (403); wherein the first buffer strike surface (401) is arranged to contact the first contact surface (505) of the buffer device (121), and wherein the second buffer strike surface (403) is arranged to contact the second contact surface (507) of the buffer device (121); wherein the first buffer strike surface (401) comprises a cross-beam of the frame and the second buffer strike surface (403) comprises a safety plank of the frame.
4. An elevator system comprising: a hoistway (103); an elevator car (101) and/or a counterweight (109) arranged to move within the hoistway (103); a buffer device (121) including: a first contact structure (501) and a second contact structure (503); wherein the first contact structure (501) comprises a first contact surface (505); wherein the second contact structure (503) comprises a second contact surface (507); wherein the first contact surface (505) and the second contact surface (507) are arranged for contacting respective vertically offset surfaces of an elevator car (101) or counterweight (109); wherein the buffer device (121) is positioned at a bottom of the hoistway beneath the elevator car (101) and/or the counterweight (109); wherein the elevator car (101) and/or counterweight (109) comprises a first buffer strike surface (401) and a second buffer strike surface (403); wherein the first buffer strike surface (401) is arranged to contact the first contact surface (505) of the buffer device (121), and wherein the second buffer strike surface (403) is arranged to contact the second contact surface (507) of the buffer device (121); wherein the second buffer strike surface (403) comprises an hole (405), wherein the hole (405) is larger than the first contact surface (505) of the buffer device (121), the first contact surface (505) positioned to pass through the hole (405) and contact the first buffer strike surface (403).
5. The elevator system of claim 4, wherein the second contact surface (507) is vertically offset from the first contact surface (505) by a first distance.
6. The elevator system of claim 4, wherein the first contact structure (501) and/or the second contact structure (503) are elastically deformable.
7. The elevator system of claim 4, wherein the second contact surface (507) is substantially parallel to the first contact surface (505).
8. The elevator system of claim 4, wherein the second contact surface (507) substantially surrounds the first contact surface (505), wherein optionally the second contact surface (507) and the first contact surface (505) are concentric.
9. The elevator system of claim 4, wherein the first contact structure (501) is formed from a first material, and wherein the second contact structure (503) is formed from a second material.
10. The elevator system of claim 9, wherein the first contact structure (501) and/or the second contact structure (503) are cylindrical and wherein the first contact surface (505) and/or the second contact surface (507) comprise an end face of the cylinders.
11. The elevator system of claim 4, wherein the buffer device (121) is a spring-type buffer, and wherein the first and/or second contact structure (503) comprises one or more resilient members.
12. The elevator system of claim 4, wherein the buffer device (121) is a hydraulic or oil buffer, and wherein the first and/or second contact structure (503) comprises a hydraulic ram.
13. The elevator system of claim 4, wherein the first buffer strike surface (401) and/or the second buffer strike surface (403) forms part of a frame of the elevator car (101.
14. The elevator system of claim 4, wherein the first buffer strike surface (403) and the second buffer strike surface (405) are separated by a second distance, and wherein the second distance is equal to the first distance.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Certain preferred examples of this disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:
(2) FIG. 1 is a schematic view of an elevator system employing a buffer device according to an example of the present disclosure;
(3) FIGS. 2A and 2B are schematic diagrams showing an elevator car of an elevator system according to an example of the present disclosure; and
(4) FIGS. 3A and 3B show the interaction between a buffer device and an elevator safety plank according to the prior art;
(5) FIGS. 4A and 4B show the interaction between a buffer device and an elevator safety plank and cross-beam according to an example of the present disclosure;
(6) FIGS. 5A and 5B show an elevator buffer device according to an example of the present disclosure; and
(7) FIGS. 6A-6C are schematic diagrams showing elevator buffer devices according to further examples of the present disclosure.
DETAILED DESCRIPTION
(8) FIG. 1 illustrates an elevator system 100 comprising an elevator car 101 that runs in a hoistway 103 between various landings 105 of a building. Although a single landing 105 is shown for illustrative purposes, it will be appreciated that more landings are present within the building but are not shown in FIG. 1 for simplicity.
(9) The elevator car 101 is suspended in the hoistway 103 by the first end of a tension member 107 (e.g. one or more ropes or belts). The second end of the tension member 107 is connected to a counterweight 109. The elevator car 101 and the counterweight 109 are moving components in the elevator system 100. Although the elevator car 101 and the counterweight 109 shown in FIG. 1 are connected by a tension member 107, it will be appreciated that in other examples the elevator system may be ropeless, e.g. using linear motors or other propulsion systems.
(10) During normal operation, the elevator car 101 travels up and down in the hoistway 103 to transport passengers and/or cargo between landings 105 of the building. The elevator car 101 is driven by a drive system 111 comprising a drive motor 113 and a motor brake 115. The tension member 107 passes over a drive sheave (not shown) that is driven to rotate by the drive motor 113 and is braked by the motor brake 115. Operation of the drive system 111 is controlled by an elevator controller 117, which is in signal communication with the drive system 111. In addition to the motor brake 115, the elevator system includes elevator car safety brakes 119, arranged to arrest motion of the elevator car 101 in the event that an emergency stopping operation is required. Such safety brakes 119 typically stop the car 101 by frictionally engaging with guiderails in the hoistway 103, although it will be appreciated that any suitable safety brake 119 may be employed.
(11) The elevator system 100 also includes a buffer group comprising two buffer devices 121 located in a pit 123 of the hoistway 103. The buffer devices 121 project upwards from the floor of the pit 123. The buffer devices 121 are arranged such that the elevator car 101 or counterweight 109 will strike them in the event that either component descends too far within the hoistway 103 in order to decelerate the elevator car 101 or the counterweight 109. In the following, an interaction between the buffer device 121 and the elevator car 101 is described, however it will be appreciated that the description is equally applicable to the counterweight 109. Although the buffer group shown in FIG. 1 comprises one buffer device 121 for the elevator car 101 and one buffer device 121 for the counterweight 109, it will be appreciated that the buffer group may comprise more or fewer buffer devices 121 as appropriate for the elevator system in which it is used. For example, there may two or more buffer devices 121 for the elevator car 101, and a further buffer device 121 for the counterweight 109.
(12) The buffer device 121 is arranged to strike a buffer strike component 125 of the elevator car 101 in the event that the elevator car 101 descends too far within the hoistway 103. The impact between the buffer strike component 125 and the buffer device 121 serves to decelerate the elevator car 101, ultimately arresting its motion. This may be required, for example, if the motor brake 115 and safety brakes 119 fail to completely arrest the motion of the elevator car 101 as it descends within the hoistway 103.
(13) FIGS. 2A and 2B show a front and side view respectively of the elevator car 101 according to an example of the present disclosure. The elevator car 101 can be seen to comprise a cab 201, comprising a platform 202 and a passenger cabin 203, mounted within a frame. The frame consists of a sub-frame 204 located beneath the cab 201 (the sub-frame 204 comprising a lower cross-beam as discussed further below), a crosshead (or header cross-beam) 205 located above the cab 201, and uprights 207 on either side of the cab 201, supported by side braces 209. The cab 201 is mechanically isolated from the frame by a plurality of isolating components 211 to provide vibration and noise isolation for the cab 201 in order to improve passenger comfort. According to the example shown in FIGS. 2A and 2B, the elevator car 101 is arranged to move along guide rails (not shown in FIG. 1 for simplicity) mounted within the hoistway 103, using guides 211 mounted above and below the frame of the elevator car 101.
(14) As will be described in more detail below with reference to FIGS. 3A and 3B, the elevator car 101 also comprises a buffer strike component 125, located below the elevator car 101 and arranged to strike the buffer device 121 projecting from the floor of the pit 123 of the elevator hoistway 103. The buffer strike component 125 extends horizontally in a region below the elevator car 101, and in the example shown in FIG. 2A, is formed as part of the sub-frame 204 of the elevator car 101.
(15) An example of a buffer strike component 325 according to the prior art is shown in FIGS. 3A and 3B. FIG. 3A shows a cross-beam 301, formed as part of the sub-frame 204 of an elevator car 101, which extends between the uprights 207 of the frame of the elevator car 101. A safety plank 303, arranged to contact a pair of cylindrical resilient member buffer devices 321, is mounted to the cross-beam 303 by a plurality of rivets 304 and extends in a direction substantially perpendicular to the cross-beam 301. Therefore in the prior art, the safety plank 303 forms the buffer strike component 325 arranged to strike the pair of resilient member buffer devices 321 located at the bottom of an elevator hoistway 103. The term buffer strike component may thus be construed here as referring to the safety plank 303 only, i.e. the component arranged to strike the buffer device 321. The buffer devices 321 are formed from a compressible material, such as a deformable polymer, e.g., polyurethane, and are arranged to strike a substantially flat surface of the safety plank 303, illustrated as region 307 in FIG. 3B.
(16) Conventionally, multiple buffer devices 321 are required (as shown in FIG. 3A) in order to distribute stress across the safety plank 303 that arises as a result of impact between the safety plank 303 and the buffer devices 321. However, with the improved buffer device and buffer strike design according to examples of this disclosure, stress can be better distributed in a buffer strike event, such that a single buffer device is sufficient, as will be explained in the following.
(17) FIGS. 4A and 4B show a buffer strike component 125 according to an example of the present disclosure. As can be seen in FIG. 4A, the buffer strike component 125 includes both the safety plank 403 and a cross-beam 401, formed as part of the sub-frame 204 of the elevator car 101, which extends between the uprights 207 of the elevator car 101 shown in FIG. 2A. The safety plank 403 is mounted to the cross-beam 401 by a plurality of rivets 404 and extends in a direction substantially perpendicular to the cross-beam 401. The term buffer strike component is thus used in this example to refer to the combination of the safety plank 403 and the cross-beam 401, i.e. referring to both of the components arranged to strike the buffer device 121.
(18) In contrast to the prior art safety plank 303 shown in FIGS. 3A and 3B, a hole 405 is formed in the safety plank 403 as shown in FIG. 4B, The hole 405 is generally located in the centre of the safety plank 403, and is arranged to accommodate part of the buffer device 121 according to an example of the present disclosure. The buffer strike component 125 is designed to operate with a single buffer device 121, configured such that part of the buffer device 121 can pass through the safety plank 403 (through the hole 405) to strike the cross-beam 401. The buffer device 121 is therefore shaped such that at least part of it is able to pass through the safety plank 403 (through the hole 405), allowing the buffer device 121 to simultaneously contact both the safety plank 403 and the cross-beam 401 in the event of an impact between the elevator car 101 and the buffer device 121. The buffer strike component 125 of the present disclosure therefore comprises both a region of the safety plank 403, and a region of the cross-beam 401, which are arranged to strike a buffer device 121 according to an example of the present disclosure, located in the pit 123 of the hoistway 103.
(19) In prior art buffer strike systems, only the safety plank 303 is directly contacted by the buffer devices 321 located in the elevator hoistway 103, and the cross-beam 301 only receives force through the rivets through which it is mounted to the safety plank 303. In contrast, the buffer device 121 of the present disclosure is able to share the force of an impact directly between the safety plank 403 and the cross-beam 401 to better distribute stress between the two components.
(20) This arrangement allows the system of the present disclosure to meet required safety standards relating to the maximum stresses experienced by the safety plank 403 while implementing a single buffer device 121. It also has the advantages of reducing the weight and cost of the safety plank 403, both through the presence of the central hole 405, but also by allowing thinner sheet metal to be used as a result of safety plank 405 being subjected to lower stress, reducing the risk of deformation.
(21) According to an example of the present disclosure, the buffer device 121 comprises distinct upper and lower regions, arranged to contact the cross-beam 401 and the safety plank 403 respectively, where the upper region is arranged to pass through the hole 405 in the safety plank 403. An example of the buffer device 121 is shown in FIG. 5A. The buffer device 121 comprises a first contact structure 501 in an upper region of the buffer device 121, and a second contact structure 503 in a lower region of the buffer device. The first contact structure 501 comprises a first contact surface 505, arranged to contact the cross-beam 401 of the elevator car 101 when the upper region of the buffer device 121 passes through the hole 405 in the safety plank 403. The second contact structure 503 comprises a second contact surface 507 arranged to contact the safety plank 403 of the elevator car 101 in the area surrounding the hole 405. The buffer device 121 may be formed from the same deformable polymer (e.g. polyurethane) as prior art buffer devices such as the buffer devices 321 shown in FIGS. 3A and 3B.
(22) FIG. 5B shows the buffer device 121 in contact with the safety plank 403 and the cross-beam 401, as would occur in the event of an impact between the buffer strike component 125 and the buffer device 121 in the event that the elevator car 101 descends too far within the hoistway 103. It can be seen in FIG. 5B that the first contact surface 505 is in contact with the cross-beam 401 (as indicated by the arrow 509) in the area behind the hole 405, while the second contact surface is in contact with the safety plank 403 (as indicated by the arrows 511) in the area around the periphery of the hole 405. The vertically offset cross-beam 401 and safety plank 403 therefore form first and second buffer strike surfaces arranged to contact the first contact surface 505 and the second contact surface 507 of the buffer device 121 respectively.
(23) To enable contact with the first and second contact surfaces 505, 507, the difference in height, D, between the first contact surface 505 and the second contact surface 507 is preferably selected such that it is substantially equivalent to the vertical offset, d, between the contact regions of the safety plank 403 and the cross-beam 401. However, while in the example shown in FIG. 5B, the difference in height between the first contact surface 505 and the second contact surface 507 is equal to this vertical offset, it will be appreciated that the two values need not be exactly equal. Instead, there is some tolerance in these values within which contact between the buffer device 121 and both of the safety plank 403 and cross-beam 401 can be achieved despite such a height difference. For example, as the buffer device 121 is deformable (and some amount of deflection of the cross-beam 403 may occur), the first contact structure may extend above the second contact structure by a distance slightly greater than the vertical offset between the cross-beam 401 and the safety plank 403, while still allowing contact with both the cross-beam 401 and the safety plank 403 following some deformation of the buffer device 121 and/or cross beam 401. In other examples, the first contact structure may extend above the second contact structure by a distance slightly less than the vertical offset between the cross-beam 401 and the safety plank 403, while still allowing contact with both the cross-beam 401 and the safety plank 403 following some deformation of the buffer device 121 and/or the safety plank 403. However, it is nonetheless preferable that the difference in height D between the first contact surface 505 and the second contact surface 507 is substantially equivalent to the vertical offset d between the contact regions of the safety plank 403 and the cross-beam 401 to ensure contact is simultaneous.
(24) While in the example shown in FIG. 5A, the buffer device 121 can be seen to have the form of two stacked cylinders having different diameters, it will be appreciated that alternative designs may achieve the same beneficial effects, as long as respective buffer strike surfaces of the elevator car 101 (i.e. the safety plank 403 and the cross-beam 401 in the examples described above) are impacted at substantially the same time by the buffer device 121. It will be further appreciated that alternative buffer designs will require that the shape of the hole 405 formed in the safety plank 403 be modified accordingly, such that a portion of such an alternative buffer device is able to protrude through the hole and contact the cross-beam 401.
(25) The first contact surface 505 and the second contact surface 507 have approximately equal areas (although the first contact surface 505 may be slightly larger than the second contact surface 507, with a ratio of about 0.6-0.7), the relative area sizes determining the load distribution between the cross-beam 401 and the safety plank 403 during a buffer strike event.
(26) It will be appreciated that in other examples the buffer device 121 could be shaped so as to contact the cross-beam 401 and the safety plank 403 with contact surfaces that are arranged side by side. In such examples, a hole 405 through the safety plank 403 may not be necessary. However, embodiments including the hole 405 have been found to allow a buffer device 121 having a compact and effective shape to be used. In particular, although a hole 405 is provided in the safety plank 403, the safety plank 403 shares the load with the cross-beam 401 and therefore experiences overall lower stresses and deformations.
(27) Although the buffer device 121 is shown as being a resilient material buffer in FIGS. 4A-5B, it is contemplated that other buffer types, such as spring-type, hydraulic, or oil-type buffers could be employed in accordance with the present disclosure, while still achieving the same beneficial effects described above. Examples of such alternative buffer designs are shown in FIGS. 6A-6C.
(28) FIG. 6A shows a hydraulic-type buffer device 621 according to an example of the present disclosure. The buffer device 621 comprises an upper first contact structure 601, and a lower second contact structure 603, formed as part of a hydraulic ram 622. The first contact structure 601 comprises a first contact surface 605, arranged to contact the cross-beam 401 of the elevator car 101 when the first contact structure of the buffer device 621 passes through the hole 405 in the safety plank 403. The second contact structure 603 comprises a second contact surface 607, arranged to contact the safety plank 403 of the elevator car 101 in the area surrounding the hole 405. The hydraulic ram 622 on which the first contact structure 601 and second contact structure 603 are mounted comprises a piston 604 extending within a partially fluid-filled cylinder 606. The fluid may be oil, water, or any fluid capable of providing hydraulic damping as is known in the art. In the event of impact with the elevator car 101 at the first and second contact surfaces 601, 603, the piston 604 is pushed into the fluid-filled cylinder 606, displacing fluid and dissipating energy of the impact and decelerating the elevator car 101 as is known in the art. The buffer device 621 also comprises a spring 609 to provide additional cushioning of impact with the elevator car 101.
(29) FIG. 6B shows a resilient member type (or spring type) buffer device 631 according to an example of the present disclosure. The buffer device 631 comprises an upper first contact structure 611, and a lower second contact structure 613. The first contact structure 611 comprises a first contact surface 615, arranged to contact the cross-beam 401 of the elevator car 101 when the first contact structure 611 of the buffer device 631 passes through the hole 405 in the safety plank 403. The second contact structure 613 comprises a second contact surface 617, arranged to contact the safety plank 403 of the elevator car 101 in the area surrounding the hole 405. The first contact surface 611 and the second contact surface 613 are arranged to strike the cross-beam 401 and the safety plank 403 respectively at substantially the same time. The first contact structure 611 and the second contact structure 613 are mounted on a resilient member 612, which is fixed to a mount 614. The resilient member 612 is arranged to be compressed upon impact of the first contact surface 611 and the second contact surface 613 with the elevator car 101, absorbing a portion of the impact force.
(30) FIG. 6C shows a second resilient member type (or spring type) buffer device 641 according to an example of the present disclosure. The buffer device 641 comprises a first resilient member 618 and a second resilient member 619. The first resilient member 618 forms a first contact structure, and the second resilient member forms a second contact structure. The second resilient member 619 substantially surrounds the first resilient member 618, and in the example shown the two components are coaxial. The first resilient member 618 is fixed to a mount 620, such that it is located above the second resilient member 619. It will be appreciated however that the mount 620 could be removed and the size of the first resilient member 618 increased accordingly. The first resilient member comprises a first contact surface 623, arranged to contact the cross-beam 401 of the elevator car 101 when the first contact resilient member 618 of the buffer device 641 passes through the hole 405 in the safety plank 403. The second resilient member 619 comprises a second contact surface 625, arranged to contact the safety plank 403 of the elevator car 101 in the area surrounding the hole 405. The first contact surface 623 and the second contact surface 625 are arranged to strike the cross-beam 401 and the safety plank 403 respectively at substantially the same time, and to compress in response to such an impact to absorb some of the energy of the impact, decelerating the elevator car 101.
(31) The use of a buffer strike component 125 and buffer device 121 as described herein, i.e. which serves to distribute the impact force between both the cross-beam 401 and the safety plank 403, has been found to result in improved performance in comparison to prior art buffer devices which only contact the safety plank 403, such as the buffer devices 321 shown in FIGS. 3A and 3B. In particular, following impact with the buffer device 121 according to the present disclosure, the maximum stress introduced in the safety plank 403 is seen to be reduced in comparison to the stress introduced in the prior art safety plank 303 following impact with the prior art buffer devices 321. The maximum deformation of the safety plank 403 following impact with the buffer device 121 has also been found to be reduced in comparison to that seen in the prior art safety plank 303 following impact with the buffer devices 321. As the stresses introduced in, and deformation of, the safety plank 403 are reduced, the safety plank 403 may be formed using thinner and lighter material than in prior art implementations. This may allow manufacturing costs of the safety plank 403 to be reduced.
(32) It will be appreciated by those skilled in the art that the disclosure has been illustrated by describing one or more specific aspects thereof, but is not limited to these aspects; many variations and modifications are possible, within the scope of the accompanying claims.
