PROGRESSIVE ELEVATOR SAFETY BRAKE

Abstract

An elevator safety brake (300) for use in an elevator system, the safety brake includes a safety block (310) substantially made of a polymeric material or a polymer-based composite material. The safety block (310) comprising: an elongate channel (320) defining a channel axis (325), wherein the elongate channel (320) is for receiving an elevator guide rail (330) of the elevator system when in use; and a cavity (340). The safety brake (300) further comprises a first braking component (250, 350) housed in the cavity (340), wherein the first braking component (250, 350) comprises a body (360) and a first braking surface (370). The safety brake (300) further comprises a second braking component (380) comprising a second braking surface (390). The first braking component (250, 350) is arranged on one side of the elongate channel and the second braking component is arranged on the other side of the elongate channel.

Claims

1. An elevator safety brake (200, 300) for use in an elevator system (10), the safety brake (200, 300) comprising: a safety block (210, 310), wherein the safety block (210, 310) is substantially made of a polymeric material or a polymer-based composite material, the safety block (210, 310) comprising: an elongate channel (220, 320) defining a channel axis (325), wherein the elongate channel (220, 320) is for receiving an elevator guide rail (330) of the elevator system (10) when in use; and a cavity (240, 340); wherein the safety brake (200, 300) further comprises: a first braking component (250, 350) housed in the cavity (240, 340), wherein the first braking component (250, 350) comprises a body (260, 360) and a first braking surface (270, 370); a second braking component (280, 380) comprising a second braking surface (290, 390); wherein the first braking component (250, 350) is arranged on one side of the elongate channel (220, 320) and the second braking component (280, 380) is arranged on the other side of the elongate channel (220, 320); wherein the first braking component (250, 350) is arranged to move in a direction generally parallel to the channel axis between a first position (A) and a second position (B); and wherein, when the first braking component (250, 350) is in the first position (A), the first braking surface (270, 370) and the second braking surface (290, 390) define a first separation distance (D.sub.1), and when the first braking component (250, 350) is in the second position (B), the first braking surface (270, 370) and the second braking surface (290, 390) define a second separation distance (D.sub.2), wherein the second separation distance (D.sub.2) is smaller than the first separation distance (D.sub.1).

2. The safety brake (200, 300) as claimed in claim 1, wherein the safety block (210, 310) is formed as a single unitary piece.

3. The safety brake (200, 300) as claimed in claim 1, wherein the polymeric material or polymer-based composite comprises a polyimide, a polyamide, a polyacrylamide, a polyketone, or a polyether ether ketone (PEEK).

4. The safety brake (200, 300) as claimed in claim 3, wherein the polymeric material or polymer-based composite comprises polyetherimide.

5. The safety brake (200, 300) as claimed in claim 1, wherein the body of the first braking component (250, 350) is made of polymeric material or polymer-based composite material.

6. The safety brake (200, 300) as claimed in claim 1, wherein the first braking surface (270, 370) is made from a metallic or metal-based composite material.

7. The safety brake (200, 300) as claimed in claim 1, wherein the first braking component (250, 350) further comprises a second surface (385) on the opposite side of the body to the first braking surface (270, 370), wherein the second surface (385) comprises a friction-reducing component.

8. The safety brake (200, 300) as claimed in claim 7, wherein the friction-reducing component comprises a plurality of rolling elements (610).

9. The safety brake (200, 300) as claimed in claim 1, wherein the first braking surface (270, 370) is made of a material that has a higher coefficient of friction than the material of the second braking surface (290, 390).

10. The safety brake (200, 300) as claimed in claim 1, wherein the safety block (210, 310) includes a stopper (255, 355), and wherein the first braking component (250, 350) may further move between the second position (B) and a third position (C); wherein, when the first braking component (250, 350) is in the third position (C), the first braking surface (270, 370) and the second braking surface (290, 390) define a third separation distance (D.sub.3), wherein the third separation distance (D.sub.3) is smaller than the second separation distance (D.sub.2); and when the first braking component (250, 350) is in the third position (C) the first braking component (250, 350) engages the stopper (255, 355) such that the separation distance (D.sub.3) is at a minimum.

11. The safety brake (200, 300) as claimed in claim 10, wherein the safety block (210, 310) further comprises a substantially cylindrical bore (205) which extends through a wall of the safety block (210, 310) into the cavity (240, 340) and an internally threaded component (235) arranged within the substantially cylindrical bore (240, 340) to receive the stopper (255, 355) such that the stopper (255, 355) is adjustable.

12. The safety brake (200, 300) as claimed in claim 11, wherein the polymeric material or a polymer-based composite material of the safety block is formed around the internally threaded component (235).

13. An elevator system (10) comprising: an elevator car (16); a guide rail (20, 330); an elevator safety brake (200, 300) mounted on the elevator car (16), the safety brake (200, 300) comprising: a safety block (210, 310), wherein the safety block (210, 310) is substantially made of a polymeric material or a polymer-based composite material, the safety block (210, 310) comprising: an elongate channel (220) defining a channel axis (225, 325), wherein the elongate channel (220) receives the elevator guide rail (20, 330) of the elevator system (10); and a cavity (240, 340); wherein the safety brake (200, 300) further comprises: a first braking component (250, 350) housed in the cavity (240, 340), wherein the first braking component (250, 350) comprises a body (260, 360) and a first braking surface (270, 370); a second braking component (280, 380) comprising a second braking surface (290, 390); wherein the first braking component (250, 350) is arranged on one side of the guide rail (20, 330) received in the elongate channel and the second braking component is arranged on the other side of the guide rail (20, 330) received in the elongate channel; wherein the first braking component (250, 350) is arranged to move in a direction generally parallel to the channel axis between a first position and a second position (B); and wherein, when the first braking component (250, 350) is in the first position, the first braking surface (270, 370) and the second braking surface (290, 390) define a first separation distance (D.sub.1) that is greater than a width of the guide rail (20, 330) and when the first braking component (250, 350) is in the second position (B), the first braking surface (270, 370) and the second braking surface (290, 390) define a second separation distance (D.sub.2), wherein the second separation distance (D.sub.2) is less than the first separation distance (D.sub.1); and wherein, when the first braking component (250, 350) is in the second position, the first braking surface (270, 370) engages the elevator guide rail (20, 330) such that a braking force is applied thereto.

14. A method (700) of manufacturing a safety block (210, 310), the method (700) comprising: preparing a polymeric material or a polymer-based composite material for moulding (710); and introducing the polymeric material or the polymer-based material into a mould (730); wherein the mould is arranged to produce a safety block (210, 310) comprising: an elongate channel (220) defining a channel axis (225, 325), wherein the elongate channel (220) is for receiving an elevator guide rail (20, 330) of the elevator system (10) when in use; and a cavity (240, 340) for housing a first braking component (250, 350); wherein the cavity is suitable for the first braking component (250, 350) to have a first position (A) and a second position (B), and for the first braking component to move therebetween in a direction generally parallel to the channel axis; and removing the safety block (210, 310) from the mould.

15. The method of claim 14, wherein the method further comprises: inserting (720) an internally threaded component into the mould before introducing the polymeric material or the polymer-based material into the mould such that the internally threaded component is overmoulded.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0090] FIG. 1 shows an elevator system.

[0091] FIG. 2 shows an exploded view of a safety brake according to an example of the present disclosure.

[0092] FIG. 3 shows a safety brake according to an example of the present disclosure with the first braking component in the first position.

[0093] FIG. 4 shows a safety brake according to an example of the present disclosure with the first braking component in the second position.

[0094] FIG. 5 shows a safety brake according to an example of the present disclosure with the first braking component in the third position.

[0095] FIG. 6 shows a first safety component according to an example of the present disclosure.

[0096] FIG. 7 shows a flow chart of the method according to an example of the present disclosure.

DETAILED DESCRIPTION

[0097] FIG. 1 shows an elevator system, 10. The elevator system 10 includes cables or belts 12, a car frame 14, an elevator car 16, roller guides 18, guide rails 20, a governor 22, and a pair of safety brakes 24 mounted on the elevator car 16. The governor 22 is mechanically coupled to actuate the safety brakes 24 by linkages 26, levers 28, and lift rods 30. The governor 22 includes a governor sheave 32, rope loop 34, and a tensioning sheave 36. The cables 12 are connected to the car frame 14 and a counterweight (not shown) inside a hoistway. The elevator car 16, which is attached to the car frame 14, moves up and down the hoistway by a force transmitted through the cables or belts 12 to the car frame 14 by an elevator drive (not shown) commonly located in a machine room at the top of the hoistway. The roller guides 18 are attached to the car frame 14 to guide the elevator car 16 up and down the hoistway along the guide rails 20. The governor sheave 32 is mounted at an upper end of the hoistway. The rope loop 34 is wrapped partially around the governor sheave 32 and partially around the tensioning sheave 36 (located in this example at a bottom end of the hoistway). The rope loop 34 is also connected to the elevator car 16 at the lever 28, ensuring that the angular velocity of the governor sheave 32 is directly related to the speed of the elevator car 16.

[0098] In the elevator system 10 shown in FIG. 1, the governor 22, a machine brake (not shown) located in the machine room, and the safety brakes 24 act to stop the elevator car 16 if it exceeds a set speed as it travels inside the hoistway. If the elevator car 16 reaches an over-speed condition, the governor 22 is triggered initially to engage a switch, which in turn cuts power to the elevator drive and drops the machine brake to arrest movement of the drive sheave (not shown) and thereby arrest movement of elevator car 16. If, however, the elevator car 16 continues to experience an overspeed condition, the governor 22 may then act to trigger the safety brakes 24 to arrest movement of the elevator car 16 (i.e. an emergency stop). In addition to engaging a switch to drop the machine brake, the governor 22 also releases a clutching device that grips the governor rope 34. The governor rope 34 is connected to the safety brakes 24 through mechanical linkages 26, levers 28, and lift rods 30. As the elevator car 16 continues its descent, the governor rope 34, which is now prevented from moving by the actuated governor 22, pulls on the operating levers 28. The operating levers 28 actuate the safety brakes 24 by moving the linkages 26 connected to the lift rods 30, and the lift rods 30 cause the safety brakes 24 to engage the guide rails 20 to bring the elevator car 16 to a stop.

[0099] Whilst mechanical speed governor systems are still in use in many elevator systems, others are now implementing electronically actuated systems to trigger the emergency safety brakes 24. And while the elevator system 10 has been illustrated with cables or belts 12 to move the elevator car 16, the safety brakes 24 will work with ropeless elevator systems as well, for example hydraulic drive, linear motor drive, pinched wheel propulsion, any other ropeless design.

[0100] FIG. 2 shows an exploded view of a safety brake 200 according to an example of the present disclosure. The safety brake 200 comprises a safety block 210, wherein the safety block 210 is substantially made of a polymeric material or a polymer-based composite material. The safety block 200 comprises an elongate channel 220 defining a channel axis 225, wherein the elongate channel 220 is for receiving an elevator guide rail (not shown) of the elevator system when in use.

[0101] The safety block 210 comprises a cavity 240 and the cavity 240 houses the first braking component 250 of the safety brake 200. The first braking component 250 includes a body 260 and a first braking surface 270. The safety brake 210 also includes a second braking component 280 which includes a second braking surface 290. The first braking component 250 is arranged on one side of the elongate channel 220 and the second braking component 280 is arranged on the other side of the elongate channel 220.

[0102] The safety block 210 includes a substantially cylindrical bore 205 which extends through a wall 205 of the safety block 210 into the cavity 240. An internally threaded component 235 is received within the substantially cylindrical bore 205 to provide a thread within the substantially cylindrical bore 205. The threaded component 235 is held within the substantially cylindrical bore 205 by engagement between protrusions 245 (and at least one indentation 247) on the outer surface of the threaded component 235, and the corresponding indentations (and a corresponding protrusion, e.g. keying feature), which are not shown, on the interior surface of the substantially cylindrical bore 205. The protrusions 245 prevent the threaded component 235 from pulling out axially, while the indentation 247 avoids rotation.

[0103] Received within the internally threaded component 235 is a stopper 255, in the form of a screw in this example. The threaded component 235 has a complementary thread to the thread on the shaft 265 of the screw 255. The screw 255 may therefore be turned within the threaded component 235 such that the extent to which the shaft 265 extends into the cavity 240 may be adjusted. The screw 255 therefore acts as an adjustable stopper to engage with the first braking component 250 when the safety brake 200 is actuated and the first braking component 250 is in a position to supply the maximum potential force to the guide rail. The nut 245 may then secure the screw 255 in the desired position.

[0104] FIGS. 3, 4 and 5 show an assembled safety brake 300 in three different positions A, B, C associated with different stages of the working of the safety brake 300. The safety brake 300 has most of its feature in common with FIG. 2, such that the description above applies equally to the safety brake 300 seen in FIGS. 3-5.

[0105] In FIG. 3, the first braking component 350 is in the first position A where the first braking component 350 is arranged such that the first braking surface 370 does not engage the guide rail 330 (received within the channel) or the screw shaft 365 of the stopper screw 355. When the first braking component 350 is in the first position A, the first braking surface 370 and the second braking surface 390 of the second braking component 380 defines a first separation distance Di which is perpendicular to the channel axis 335 and thus parallel to the axis defining the width of the elongate channel.

[0106] When the first braking component 350 is in the first position A, a second surface 385 of the first braking component 350 engages a wall of the safety block 310 which forms the cavity.

[0107] In FIG. 4, the first braking component 350 has moved in a direction generally parallel to the channel axis from the first position A to the first position B, actually in a direction parallel to the angled second surface 385. In the second position B the first braking component 350 is arranged such that the first braking surface 370 engages the guide rail 330 (received within the channel) but the first braking component 350 does not engage the screw shaft 365 of the stopper screw 355. As such a braking force is applied to the guide rail 330 to brake the elevator car via the frictional engagement between the first braking surface 370 and the guide rail 330.

[0108] When the first braking component 350 is in the second position B, the first braking surface 370 and the second braking surface 390 of the second braking component 380 defines a second separation distance D2 which is perpendicular to the channel axis 335 and thus parallel to the axis defining the width of the elongate channel.

[0109] When the first braking component 350 is in the second position B, the second surface 385 of the first braking component 350 still engages the wall of the safety block 310 which forms the cavity, i.e. when moving from the first position A to the second position B the second surface 385 slides along the wall of the cavity.

[0110] In FIG. 5, the first braking component 350 has moved in a direction generally parallel to the channel axis from the second position B to the third position C. In the third position C, the first braking component 350 is arranged such that both the first braking surface 370 and the second braking surface 390 engage the guide rail 330 (received within the channel) and the first braking component 350 engages the screw shaft 365 of the stopper screw 355. As such a maximum braking force for the safety brake 300 is applied to the guide rail 330 to brake the elevator car via the frictional engagement between the first braking surface 370 and the guide rail 330 and the second braking surface 390 and the guide rail 330.

[0111] When the first braking component 350 is in the third position C, the first braking surface 370 and the second braking surface 390 of the second braking component 380 defines a third separation distance D3 which is perpendicular to the channel axis 335 and thus parallel to the axis defining the width of the elongate channel. The third separation distance D3 is smaller than the second separation distance D2 and less than the width of the guide rail 330.

[0112] When the first braking component 350 is in the third position C, the second surface 385 of the first braking component 350 maintains engagement with the wall of the safety block 310 which forms the cavity, i.e. when moving from the second position B to the third position C the second surface 385 slides along the wall of the cavity.

[0113] After braking has been effected, it will be appreciated that the elevator safety brake 300 may be disengaged. As such, disengagement of the safety brake 300 may be represented as the opposite of the process of actuation shown in FIGS. 3-5.

[0114] For example, after the safety brake 300 has been disengaged (e.g. released) the first braking component 350 will move from the third position C (FIG. 5) to the second position B (FIG. 2). This movement will primarily result from the movement of the elevator car (i.e. moving the safety block 310) relative to the first braking component 350 such that the separation distance D between the first braking surface 370 and the second braking surface 390 is increased.

[0115] Eventually, the first braking component 350 will reach the second position B, which effectively defines the point of first engagement between the elevator guide rail 330 and the first braking surface 370 (e.g. the first position at which a braking force is applied). Thus further movement of the elevator car (after deactivation of the safety brake) will result in the first braking surface 370 being disengaged from the guide rail 330 and gravity acting to move the first braking component 350 back to the first position A.

[0116] FIG. 6 shows a first braking component 650 according to an example of the present disclosure. The first braking component 650 comprises a body 660 and a surface component, wherein in the example shown, the surface component is in the form of an insert 665. The insert 665 forms the first braking surface 670 of the first braking component 650. The insert component 665 includes a protrusion 635 on the surface of the insert 665 which is opposite to the first braking surface 670. The body 660 of the first braking component 650 comprises at least one corresponding indentation 620 which is arranged to receive the protrusion 635 of the insert component 665, wherein the engagement of the protrusion 635 and the indentation 620 acts to secure the insert component 665 to the body 660 of the first braking component 650.

[0117] The first braking component 650 has a second surface 685 on the opposite side of the body 660 to the first braking surface 670. The second surface 685 includes a friction reducing component which includes a row of roller bearings 610 trapped by a metal plate 625. The metal plate 625 is affixed to the body 660 of the first braking component 650 by a screw 695 which extends through the metal plate 625 and the body 660 of the first braking component 650 and is secured by a nut 655 which is received within a recess 645 in the body 660 (so that the screw and nut do not extend beyond the plane formed by the first braking surface 670).

[0118] The first braking component 650 incudes a bore 675 which is arranged to provide a connection point to connect the first braking component 650 to a linkage (not shown). The bore 675 may be threaded (i.e. a female thread) such that it is arranged to receive a threaded screw comprising a complementary (i.e. male) thread, wherein the screw is also attached to (e.g. in connection with) the linkage. Alternatively the bore 675 may receive a pin to connection with the linkage.

[0119] FIG. 7 shows an exemplary method 700 of manufacturing a safety block which will be discussed with reference to FIGS. 2-5. The material used to make the safety block is substantially a polymeric material, or polymer-based composite material.

[0120] The method 700 first requires the material to be prepared at step 710 for moulding. The preparing step 710 for a polymeric material or polymer-based composite material includes heating the material to a temperature above at least one of the glass transition temperature or the melting point of the polymer. For a polymer-based composite material, the preparing step 710 optionally includes adding a fibre reinforcement in advance of the moulding step 730.

[0121] Whilst the material is being prepared at step 710 for moulding, the threaded component 235 may be introduced to the mould in step 720. For example, the threaded component 235 may be placed in a position such that the substantially cylindrical bore 205 will be formed around the threaded component when the polymeric material or polymer-based composite material is introduced into the mould (i.e. the threaded component is over moulded).

[0122] Once heated to an appropriate temperature, the material is introduced (e.g. injected, e.g. poured) at step 730 into the mould (arranged to produce the safety block 210 described herein). For a polymer-based composite material, the moulding step 730 optionally includes adding a fibre reinforcement. Once the material has been injected within the mould, the material is allowed to cool to a temperature below the materials glass transition temperature in step 740 before removing at least part of the mould. By allowing the material to partially cool, it is ensured that the material substantially retains the shape of the mould cavity to provide the desired shape of the safety block.