GB2241488A

GB2241488A - Lift brake with safety release

Info

Publication number: GB2241488A
Application number: GB9104245A
Authority: GB
Inventors: Edwin George Pink; Michael John Nicholas Manning
Original assignee: ALPHATRAD SA
Current assignee: ALPHATRAD SA
Priority date: 1990-03-01
Filing date: 1991-02-28
Publication date: 1991-09-04
Anticipated expiration: 2011-02-28
Also published as: FR2659072A1; BR9100835A; CA2037231C; DE4106595C2; GB9004643D0; GB2241488B; FR2659072B1; GB9104245D0; CA2037231A1; DE4106595A1; ZA911490B; ZW1991A1; AU7207091A; AU632667B2

Abstract

In a linear motor driven mine shaft conveyance system, brake 22 is released when load cells 34 sense a predetermined vertical load on the brake eg 90% of the upward thrust required to support the dead weight of the conveyance. Thus caliper pads 28 acting on vertical guide rails may be released by hydraulic actuators 26 operating against spring forces. The brake may be mounted on the conveyance or the reaction member. <IMAGE>

Description

TRAKING APpARAThsw TillS invention relates to a braking apparatus to be used in a shaft conveyance system, It has already been proposed in PCt/GB90 90/00335 to provide a mine shaft conveyance system in which linear motors are used to transport men, ore and materials to and from the surface in a mine shaft. This contrasts with the conventional mine shaft conveyance system in which mine conveyances, such as personnel cages and ore and material skips are suspended at the ends of ropes which are paid out and wound in by sUce, or in some cases, unuerground, winding apparatus.

A first aspect of the present invention provides a braldng apparatus for a shaft conveyance system in which a conveyance is driven up and down an upright track in the shaft, the braking apparatus comprising a brake associated with the conveyance which is operable to engage a counter-member in the shaft to hold the conveyance at a chosen elevation on the track, a load cell for sensing the vertical load on the brake when it is engaged with the counter-member and means operable in response to the load cell to disengage the brake from the counter-member when the load cell senses a predetermined load on the brake.

The shaft is typically a mine shaS The conveyance system may be of the linear motor type disclosed in PCf/GB90/00335. Accordingly, a second aspect of the invention provides a braking apparatus for a shaft conveyance system in which a conveyance carried by a reaction member is driven up and down the shaft, by electromagnetic forces, relative to a winding support member extending vertically in the shaft, the braking apparatus comprising a brake on the conveyance or reaction member which is operable to engage a counter-member extending werticallly in the shaft to hold the conveyance and reaction member at a chosen elevation in the shaft, a load ceU for sensing the vertical load on the brake when it is engaged with the counter-member and means operable in response to the load cell to disengage the brake when the load cell senses a predetertnined vertical load on the brake.

In the interests of safety, the brake is preferably of the spring-applied, hydraulically released type. In a preferred brake construcuon, the brake includes a caliper carrying brake pads which are adapted to engage the counter-member between them under spring force and wherein the means for disengaging the brake from the counter-member includes hydraulic actuators operable to separate the brake pads against the spring force.

There may be a housing accommodating the caliper and a mounting plate for mounting the brake on the conveyance, the load cell being arranged between the housing and the mounting plate and being sensitive to tension or compression applied to it.

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a diagrammatic horizontal cross-section through a mine shaft; Figure 2 shows an exploded view of a braking apparatus of the invention; and Figure 3 shows a side view of the assembled braking apparatus.

In Figure 1, the numeral 10 designates a vertical, circular cross-section mine shaft.

Fixed in the shaft is steelwob; which includes stnictutttl members 12 and 14. The members 14, which are located at vertically spaced intervals in the shaft, have Tsection brake reaction rails 16 fixed to them as illusirated, the members 16 extending in the shaft from the top to the bottom thereof Figure 1 also shows two mine conveyances 18, such as ore, personnel or equipment conveyances which are driven vertically up and down the shaft as required by electromagnetic forces generated by linear motors indicated generally with the numeral 20. Each linear motor is constituted by a vertically extending winding support member and a reaction member, typically incorporating permanent magnets, as described in the specification of PCT/GB 90/00335. The conveyances 18 are carried by the reaction members of the linear motors4 Caliper brakes 22 are mounted on the conveyances 18, although it is also within the scope of the invention for the brakes to be mounted directly on the reaction members. Referring to Figures 2 and 3, each caliper brake has a mounting plate 24 which is secured to the underside of the conveyance and a pair of hydraulic brake actuators 26 which act on a caliper carrying brake pads 23 of friction material.

The brakes 22 are mounted on the conveyances 18 in such positions that the webs 30 of the counter-members 16 are located between the brake pads 28. The brakes are of the spring-applied, hydraulically released type. Thus the normal operation of the springs in the actuators is to apply the brakes, ie. to force the brake pads 28 together to clamp the webs 30 between thez When the brakes are to b,e released, hydraulic fluid is supplied to release cylinders in the actuators which pull the brake pads apart and off the webs 30.

Between the mounting plate 24 and the caliper housing 39 of each brake 22 is a series of load cells 34 which may be of a conventional type designed to sense vertical loads tending to force the plate 24 towards the housing 32 or tending to force the plate and housing apart When a conveyance 18 is travelling vertically in the shaft 10 under electromagnetic forces and it is desired to brake the conveyance at a desired elevation, an electromagnetic control is used to decelerate the conveyance to zero speed and then hold the conveyance in a "hover" mode at the desired elevadom Hydraulic feed to the actuators is teninaled and the springs apply the brakes to clamp the conveyance relative to the counter-members 16. The electrical sllpply to the winding support members of the linear motors can now be terminated and the conveyance remains in a stationary position, held only by the mechanical braking forces.

If it is now desired to cause the conveyance to rise or descend, the electrical supply to the winding support members is re-establishedv It will be appreciated that it will take a short time for the linear motors to build up sufficient thrust to support the weight of the conveyance and its contents, and in the case of upward movement, to lift it. It would clearly be extremely dangerous for the brakes to be released too early, since this could have the result that the conveyance falls down the shaft under gravity.

Assuming that the conveyance is to be lifted up the shaft by the linear motors, the load cells 34 will come under rension as the linear motors build up thrust. It is only when a predetermined thrust has been attained that the load cells relay a signal to a hydraulic control circuit (not shown) which operates, in response to that signal, to feed hydraulic fluid to the acruators to pull the brake pads 28 aparL Normally the load cells will not permit the brakes to be released undl at least about 90% of the thrust required to take the dead weight of the conveyance and its contents is attained. This will permit the conveyance to drop a small distance before the filll thrust is attained to take the weight of the conveyance and contents, whereafter further thrust which is generated will serve to lift the conveyance and contents.

If it is intended that the conveyance will descend in the shaft from its braked position, the load cells will again sense when sufficient thrust has been built up to take at least the major part of the dead weight of the conveyance and contents, and only then will a signal be transmitted to the hydraulic control circuit to cause the brakes to be released.

Claims

CLTS

1.

A braking apparatus for a shaft conveyance system in which a conveyance (18) is driven up and down an upright track in the shaft (10), the braking apparatus comprising a brake (22) associated with the conveyance (18) which is operable to engage a counter-member (16) in the shaft (10) to hold the conveyance (18) at a chosen elevation on the track, a load cell (34) for sensing the vertical load on the brake (?2) when it is engaged with the count member (16) and means operable in response to the load cell (34) to disengage the brake (22) from the countermember (16) when the load cell (34) senses a predetermined load on the brake (22).

2 A braking apparatus for a shaft conveyance system in which a conveyance (18) carried by a reaction member (20) is driven up and down the shaft (10), by electromagnetic forces, relative to a winding support member (20) extending vertically in the shaft (10), the braking apparatus comprising a brake (22) on the conveyance (1S) or reaction member (20) which is operable to engage a countermember (16) extending vertically in the shaft (10) to hold the conveyance (1S) and reaction member (20) at a chosen elevation in the shaft (10), a load cell (24) for sensing the vertical load on the brake (22) when it is engaged with the countermember (16) and means operable in response to the load cell (34) to disengage the brake (22) when the load cell (34) senses a predetermined vertical load on the brake (22).

A braking apparatus according to claim 1 or claim 2 wherein the brake .(22) is of the spring-applied type.

4.

A braking apparatus according to claim 3 wherein the brake (22) is of the springapplied, hydraulically released type.

5.

A braking apparatus according to claim 4 wherein the brake (22) includes a caliper carrying brake pads (28) which are adapted to engage the counter-member (16) between them under spring force and wherein the means for disengaging the brake (22) from the counter-member (16) includes hydraulic actuators (26) operable to separate the brake pads (28) against the spring force.

6.

A braking apparatus according to claim 5 wherein the brake (22) includes a housing (32) accommodating the caliper and a mounting plate (24) for mounting the brake (22) on the conveyance (1S) and wherein the load cell (34) is arranged between the housing (32) and the mounting plate (24) and is sensitive to tension or compression applied to it.

7.

A braking apparatus according to claim 6 and including a plurality of load cells (34) between the housing (32) and the mounting plate (24).

8.

A brakg apparatus according to any one of the preceding claims wherein the predetermined load is appro:wnateiy 90% of the upward thrust required to support the dead weight of the conveyance (18).

9.

A braking apparatus according to any one of the preceding claims when used in a mine shaft conveyance system.

10. A braking apparatus for a shaft conveyance system, substantially as hereinbefore described with reference to, and as shown in, Figures 2 and 3 of the accompanying drawings.

11. Any novel feature or combination of features described herein.