CA2052434C - Mine hoist braking system - Google Patents

Abstract

A braking system for mine hoists allows for primed braking while simultaneously meeting mandated deceleration rates. A series of two position valves act to dampen debilitating hoist vibrations and bring the conveyances to safe, smooth stops in emergency.

Description

MINE HOIST BRAKING ~Y~

TECHNICAL FIELD

The instant invention relates to mine hoists in general and, more particularly, to a system for safely decelerating a hoist while simultaneously allowing 5 priming control.

BACKGROUND ART
In general, larger underground mines employ double drum hoists.
Sharing a common drive shaft rotated by a large motor, two drums are individually clutched to allow dual operation or single operation (i.e. one drum is rotating while 10 the other drum is stationary). One drum will include an underwound rope whereas the other drum will include an ovt;~w(Jund rope. Both ropes pass over sheave wheels and are ultimately connected to a cage or skip.

Braking of the drums is normally controlled by modulating the speed of the motor and by physically applying braking surfaces against the drums. Larger drums 2052~3~

tend to employ parallel motion brakes: See SME Mining Engineering Handbook, ed.
by ~B. Cummins and I.A. Given, Volume 2, pages 15-43 to 15-46, The American Institute of Mining, Metallurgical and Petroleum Engineers, Inc. N.Y., N.Y. 1973 for an overview of hoist braking systems.

In older installations, the weighted brake engine is mechanically actuated by the removal of air ples~ule holding up the weights. Upon the realization of an emergency, besides other systems operating, the pneumatic or hydraulic pressure being fed to the underside (bottom) of the brake engine piston is reduced or overcome by introducing excess fluid pressule to the top side of the brake engine piston. This causes the brake engine piston to fall. Since the dropping piston is registered to the brake actuators, the brakes abruptly come on and stop the drum.

These systems cause the rope to oscillate and set up potentially (l~m~ging vibrations throughout the entire hoist and its related components.
Moreover, the sudden application of the brakes tend to suddenly decelerate the hoist at a very high rate. This abrupt stop is potentially dangerous to personnel and equipment situated in the conveyallce.

There are numerous problems with this design:
1. When leakage occurs on the topside of the brake engine (cylinders) due to escape of cylinder air by any means such as a missing grease nipple or through a leaky topside valve, the brakes cannot be applied. (Since bottom air pressure cannot be rY~ eeclecl by topside air).

2. For emergency stopping there is only one level of braking i.e.
there is no priming and a one second delay occurs before the brakes are applied. When application does occur it takes place abruptly. This sudden application results in vibrations and oscill~ting forces that induce fatigue stresses in the mechanical components.

2052~3~

3. There ls no accommodation for varlous shaft load conditions such as slngle conveyance up travel, slngle conveyance down travel or for dual conveyance travel.

4. There are no means to ad~ust the emergency stop deceleratlon rate.

5. To apply both left and rlght drum brakes properly requlres the dedlcatlon of the operator's two hands.

6. There ls no brake redundancy as requlred now by the Canadlan government.

7. Governmental regulatlons requlre a deceleratlon rate between 5-12feet/sec2tl.5-3.7 meters/sec2). Some older systems were ln excess of 18 feet/sec2t5.5-meters/sec2). What ls deslrable ls for the system to gradually but qulckly apply lncreaslng pressure to the brakes, thereby allowlng a fast but relatlvely gentle stop wlthout settlng up damaglng osclllatlons.
Accordlngly, many older braklng systems are now consldered obsolete. There have been recent attempts to redeslgn older mechanlsms and/or brlng them ln to conformance wlth recent leglslatlon. See, for example, Canadlan Patent 1,191,461 and U.S. patent 3,291,451.

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2û52~3~
- 3a -SUMMARY OF THE INVENTION
There ls provlded a braklng system for brlnglng holst to a qulck and gradual stop ln an emergency. The system permlts controlled prlmlng of the brakes so as to effect regulated braklng. By modulatlng the brake effect, deslred deceleratlon rates are achleved whlle slmultaneously avoldlng debllltatlng osclllatlons.
Accordlng to a flrst broad aspect, the present lnventlon provldes a holst braklng system, the system comprlslng means for braklng the holst, a flrst valve capable of dlrectly communlcatlng wlth the brake means, the flrst valve also capable of dlrectly communlcatlng wlth a prlmlng valve and a second valve means for selectlvely actlvatlng and deactlvatlng the flrst, second and prlmlng valves in a predetermlned manner upon the reallzatlon of an emergency sltuatlon, the prlmlng valve lncludlng a tlme delay operable ln response to the emergency sltuatlon, and the system adapted to be connected to a source of pressurlzed fluid whereby upon reallzatlon of the emergency sltuatlon alr contalned ln the brake means ls passed through the flrst valve and the prlmlng valve durlng the predetermlned delay.
Accordlng to a second broad aspect, the present lnventlon provldes a method for regulatlng the braklng of a holst havlng at least one drum and at least one brake englne, the method comprlslng: A) regulatlng the quantlty, dlrectlon and pressure of alr passlng through a flrst valve dlrectly communlcatlng wlth the brake englne, the flrst valve havlng ,~

i 2052434 - 3b -three ports A, B, and C of whlch ports A and B are stralght through ports and ports A and C are crossover ports and normally actlvatlng the flrst valve to cause the ports A and B
to be connected and dlrectly communicate wlth the brake englne; B) normally actlvatlng a prlmlng valve communlcatlng wlth the flrst valve's ports A and C, the prlmlng valve havlng two stralght through ports A and B normally connected, and the prlmlng valve's port B communlcatlng wlth the exterlor of the system; C~ upon the reallzatlon of an emergency stop condltlon, deactlvatlng the flrst valve to cause the flrst valve's ports A and C to be lmmedlately connected thereby permlttlng alr contalned ln the brake englne to vent out through the prlmlng valve vla the prlmlng valve's ports A and B; D) deactlvatlng the prlmary valve a predetermlned tlme after the first valve ls deactivated to cease venting such that a predetermlned portlon of the alr contalned ln the brake englne ls vented thereby prlmlng the brake englne.

BRIEF DESCRIPTION OF THE DRAWINGS
Flgure 1 ls a sectlonal elevatlon of an embodlment of the lnventlon.
Flgure 2 ls a schematlc of an embodlment of the lnventlon.

- 20~24~4 PREFERRED EMBODIMENT OF THE INVENTION
Figure 1 depicts a drum hoist brake system 10. Two spaced adjacent drums 12 (only the left drum is shown) share a common drive shaft 14. The drive shaft 14 ll~ns~ torque to the drums 12 through a pair of corresponding clutches (not shown). As drawn, a hoist rope 16 is ove,woulld on the right.

The brake system includes a pair of brake shoes 18 and 20 partially circumscribing the drum 12. Adjustable members 22 and 24 link the two shoes 18 and 20 together. Supports 26 and 28 uphold the brake shoes 18 and 20 in place. Pivoted levers 30 and 32, when acted upon by the arms 34 and 36, cause the brake shoes 18 and 20 to either grab or release the drum 12. An actuator bar 38 is pivotally connected to the arms 34 and 36 at bearings 40 and 42 respectively supported by member 44. The actuator bar 38 is also pivoted at bearing 46. Adjustable support 48 holds up the member 44.

The actuator bar 38 is locomoted by an inline brake engine 50. The brake engine 50 includes a cylinder 52 and a piston 54 disposed therein. A piston rod 56 communicates with the actuator bar 38. A weight 58 hangs from the piston rod 56 and the actuator bar 38.

As depicted in Figure 1, the brakes shoes 18 and 20 are in contact with the drum 12. For safety reasons, the brakes are always on by virtue of the weight 58 pulling down on the actuator bar 38. In order to release the brake shoes 18 and 20, pneumatic prc.,sure is introduced to the lower or rod end section 60 of the brake engine 50 to overcome the pull of the weight 58 and raise the actuator bar 38.

In previous brake systems, pneumatic plessure would be shuttled between the rod section 60 and the head section 62 of the cylinder 52 in order to apply or release the brakes. Mechanical levers were employed to operate the valves (not shown) feeding high pressure air into the brake engine 50. Essentially, the rod section 60 and the head section 62 each had its own valve to introduce pressurized air into their respective compartments. Inasmuch as these non-adjustable valves were -S- 2 0 ~ 2 ~ 3 ~ PC-3188 either on or off, fine braking control ("priming") was virtually impossible. The brakes either came on or were released.

Besides affording no priming capacity, due to equipment failure it was sometimes difficult to ~ve~ e the rod section 60 pres~ul~; in order to apply theS brakes.

Figure 2 represents a pneumatic schematic circuit for the instant brake system 10. Left brake engine SOA and right brake engine SOB are shown with theirrespective weights 58A and 58B. The circuits for the two engines SOA and 50B areessentially the same. The ~ ;uilly for pinion brake 64 is also shown. For non-limiting discussion purposes only, all three brakes are shown engaged. The down arrows represent the brakes being applied. The up arrows represent the brakes in the released position.

Clean dry mine air, generally at about 9S psi (655 kPa) is sourced by supply 66. The air is filtered through filter 68 and proceeds through refrigerant dryer 70 having a by-pass for maintenance purposes. Check valve 72 prevents backflow and permits a quick release if for some reason the system 10 must be freed from the main mine air supply 66. Accumulator 74 dampens out ple~ule surges and provides positive pilot line plessule. A filter, regulator, lubricator 76 and drip leg 78 further process the air. At this point, the air is split four ways from a header. Line 80 feeds a variable controller (preferably a Wabco~U H-2 Controlair~A valve) 94. Lines 82 and 84 feed the brake engines SOA and 50B as well as the clutches (not shown) and the left and right brake interlock circuits 88 and 90 respectively. Line 86 feeds the pinion brake 64.

Both brake circuits 92A and 92B are operated by the variable control valve 94. Pilot air lines 96 and 98 (of relatively low air pres~ule) actuate relay valves 100A and 100B. The relay valves 100A and 100B allow regulated air to be ultimately admitted to the brake engines 50A and SOB and more particularly to the rod sections 60 of the brake engines. (See Figure 1).

20~2434 The valves 102AIB, and 110AIB are two position, three way directional solenoid operated valves having ~ rn~l pilot air assist. The valves 106A/B are two position, two way directional solenoid operated valves having external pilot air assist.

These known valves 102AIB, 106AIB and 110A/B use "AND" logic in 5 their operation. They require both a source of low (pilot) air pressure and anelectrical signal directed to the solenoid to operate. The solenoid poppet (represented by the d(Jwllwaldly pointed triangle) acts as gate. When energized, the solenoidpoppet moves up and allows the pilot pressure to shift the position of the valve spool.
The spring retums the spool to the normal position when the electrical signal to the 10 valve or the pilot pleS:,ule are cut off.

During normal (non-emergency) operations, braking or the lack thereof is initiated by the adjustable control valve 94 (0-60 psi [0-414kPa]) through solenoid valves 102A!B via lines 96 and 98. The valves 100AIB permit air to flow through the valves 102AIB via the AIB ports into the brake engines 50A and 50B. The valves 15 102A are operating straight through with ports B and A connected. By directly varying the pilot air, the high pressure air flowing through the lines 82 and 84 is alsomodulated causing the brakes to be regulated by raising or lowering the weights 58A
and 58B. Pilot air is also supplied by a controlled supply 120AIB.

In the event of an emergency stop, a condition either manually 20 precipitated by the operator hitting an emergency switch 104 communicating with the valves 102AIB or a LillyTM controller (a standard mine hoist control means) exceeding preset safety limits, the instant invention will safely and quickly stop the hoists.

In emergency situations, the brakes are primed as they are applied.
Instead of instantly allowing the weights to drop and abruptly applying the brakes, the 25 brakes are permitted to first quickly take up clearances and then gradually apply a harder rapid squeeze on the drum. This results in a relatively smooth damped stop without the debilitating oscillations that occur when the brakes are instantly applied.

The priming mode is actuated by the de-energizing of the valves 102A/B
as is shown in Figure 2. This permits air pressure from the brake engines 50AIB to -7- 20~24~ PC-3188 pass out through crossover ports A and C of the valves 102A/B. The air then travels to the valves 106A/B which are energized for an adjustable brief period on an electrical time delay to allow the air to pass directly to the atmosphere metered by adjustable needle valves 108A/B which brings the brake pistons 54 A/B to the prime 5 brake position. The brakes are now in a position for regulated braking. Final stopping is determined by the valves 110A/B which will respond to a preset conveyance mode condition. The final stopping action will occur at adjustable desired uniform brake rates selected to overcome the undesirable oscillations.

Arbitrarily, two non-limiting preset col~v~y~nce mode conditions were 10 selected. However, with appropriate realignments, other conditions may be selected.
A) Both drums operating or single col.v~yance down (one drum locked): After the above time delay, the valves 106A/B de-energize (as shown) and the air flow passes through the valves 110A/B via the ports A and C to the adjustable restriction valves 112AIB set for the applopliate deceleration rate for this mode.
Currently, governmental regulations call for 5-12 feet/sec2 (1.5 - 3.7 meters/sec2).
Figure 2 shows the air venting out through valves 112A/B.
B) Single conveyance up: After the time delay, the valve 106 (A or B) de-energizes and the air flow is directed to the valve 110 (A or B). In this mode, the valve 110 is energized and the air flow passes via ports A and B to self-relief valve 20 114 (A or B) which is set for the mandated predetermined braking rate. Air then continues to flow out to the atmosphere through restriction valve 116(A or B). This further assists in the braking action. When the hoist convey~llce speed has fallen below 200 feet/second (61 meters/second) the valve llO(A or B) de-energizes which then directs the air through the valve 112 (A or B) for final stoppage.

Inasmuch as provisions are necessary for emergency hoist end zone conditions, all of the valves 102A/B, 106A~B and llOAIB are configured to be de-energized for full brake application with no priming. If necessary, air is immediately vented out through the valves 112A/B to bring the brakes on immediately.

Circuitry for the left and right brake interlock circuits 88 and 90 and the pinion brake circuit are shown for completeness.

2052434 PC-3l88 The brake interlock circuits operate in tandem with the clutches on the drums. Using pneumatic limit switches, the clutches cannot be disengaged withouthaving the brake(s) fully applied. Conversely, the brake(s) cannot be released unless the clutches are fully engaged.

S With respect to the interlock circuits 88 and 90 secondary pilot air for operating the valves 102AIB, 106AIB and 110AIB is supplied by the lines 120A/B.
Valves 122A/B parcel out air supplied from the main header and treated by filter124AIB and the components 68, 70, 76 and 78. For normal conditions the clutch must be engaged. A pneumatic mechanically operated limit valve (not shown) is actuated by the clutch in the engaged position. This mechanically (via a cam) shifts valves 122AIB and air is allowed to pass from the main air header through to the external pilot air supply end of valves 102AIB, 106AIB & 100AIB. Unless the clutch(es) isengaged these cannot be operated i.e. brakes released.

The pinion brake circuit 118 is utilized as a mandated backup or redundancy circuit for either left or right brake. After a predetermined delay, generally less than five seconds for normal emergency situations, the pinion brake on the main drive shaft (not shown) comes on. It will activate immediately on contact, however if the track limit in the end zone is reached.

The pinion brake circuit 118 is somewhat similar to the left and right brake circuits 92AIB in that a pair of two position / two way valves 126 and 128 are ganged together along with a self-relief valve 130. Filter 140 cleans the pilot air supplied to the valves 126 and 128.

During normal (non-emergency) operations the valve 128 is energized connecting the ports A and B. An adjustable flow valve 132 controls the air flow to the valve 128 to control the speed of the pinion brake 64 reset.

Upon the initiation of a normal emergency situation (i.e. no end run excursions) and after a five second delay the valve 128 is de-energized throwing ports 9 2052~3~ PC-3188 A and C together. The air in the pinion brake 64 is then passed to valve 126. Asabove, if both drums are operating or only one collv~;yance is going down, the air is vented through ports A and C through flow valve 134 and out to the atmosphere. If only one up collv~;y~nce is operating, the flow is passed from ports A and C, through the valve 130 and to the atmosphere via flow valve 136 and/or flow valve 138.

During an emergency end zone condition, the five second delay is defeated and the flow is immediately routed out through valve 126.

It will be appreciated that the arrangement of the valves 102A/B, 110AIB and 106AIB permit safe and vastly illlpl~v~;d control of the hoist brake system 10 as well as permitting priming no matter how the hoist schedule is configured.
In summary the following logic chart, in tabular form, illustrates the various modes of operation. The details of the logic software and the various sensors available to the art are not shown.

MODE OF OPER~TION FOR BRAKE ENGINES

1) Valves 102 & 106 are energized.
2) Brake engines 50 variably operated via control valve 94 lever on hoistmen's console.

1) BOTH DRUMS OPERATING & SINGLE CONVEYANCE DOWN
1.1) Valve 102 de-energizes.
1.2) After a 0.25 - 1.5 sec delay, valve 106 de-energizes (Priming -Field set to accommodate the particular installation) 1.3) Valve 110 is de-energized.
2) SINGLE CONVEYANCE UP
2.1) Valve 102 de-energizes.
2.2) After a 0.25 - 1.5 sec delay, valve 106 de-energizes (Priming -Field set) -lo- 2 0 5 2 4 3 4 PC-3188 2.3) Valve 110 energized.
2.4) Valve 110 de-energizes when the hoist conveyance deaccelerates to 200 feet/minute (61 meters/minute).
3) END ZONES - ALL CONDITIONS
3.1) Valve 102 de-energizes.
3.2) Valve 106 remains energized.
3.3) Valve 110 is de-energized.
Note: Times are for example only. Numbers refer to the valves in figure 2. Pinion brake operates similarly except for five second total delay under non-end zone conditions.

While in accordance with the provisions of the statute, there is illustrated and described herein specific embodiments of the invention those skilled in the art will understand that changes may be made in the form of the invention covered by the claims and the certain features of the invention may sometimes be15 used to advantage without a corresponding use of the other features.

Claims (17)

1. A hoist braking system, the system comprising means for braking the hoist, a first valve capable of directly communicating with the brake means, the first valve also capable of directly communicating with a priming valve and a second valve means for selectively activating and deactivating the first, second and priming valves in a predetermined manner upon the realization of an emergency situation, the priming valve including a time delay operable in response to the emergency situation, and the system adapted to be connected to a source of pressurized fluid whereby upon realization of the emergency situation air contained in the brake means is passed through the first valve and the priming valve during the predetermined delay.

2. The system according to claim 1 wherein the first and second valves are two position, three way directional valves having three ports A, B and C of which ports A and B
are straight through ports and ports B and C are cross over ports and the priming valve is a two position, two way directional valve having straight through ports A and B.

3. The system according to claim 2 wherein the ports A
and B of the priming valve and the ports A and C of the first valve exhaust the pressurized fluid out of the system.

4. The system according to claim 2 wherein the first valve and the priming valve normally have their respective ports A and B connected, and the brake means are released.

5. The system according to claim 2 wherein upon the realization of a first emergency condition, the ports A and C
of the first valve are connected and the ports A and B of the priming valve are disconnected after the ports A and C of the first valve are connected, and the ports A and C of the first valve are the pathway to the priming valve and the second valve.

6. The system according to claim 2 wherein the second valve normally has ports A and C connected.

7. The system according to claim 3 wherein the ports A
and B of the second valve route the pressurized fluid to a third valve and then out of the system.

8. The system according to claim 7 wherein the second valve has ports A and B connected when a second emergency condition is realized.

9. The system according to claim 1 wherein a variable control valve modulates the degree of braking caused by the brake means.

10. A method for regulating the braking of a hoist having at least one drum and at least one brake engine, the method comprising:
A) regulating the quantity, direction and pressure of air passing through a first valve directly communicating with the brake engine, the first valve having three ports A, B and C of which ports A and B are straight through ports and ports A and C are cross over ports and normally activating the first valve to cause the ports A and B to be connected and directly communicate with the brake engine;
B) normally activating a priming valve communicating with the first valve's ports A and C, the priming valve having two straight through ports A and B
normally connected; and the priming valve's port B
communicating with the exterior of the system;
C) upon the realization of an emergency stop condition, deactivating the first valve to cause the first valve's ports A and C to be immediately connected thereby permitting air contained in the brake engine to vent out through the priming valve via the priming valve's ports A and B;
D) deactivating the priming valve a predetermined time after the first valve is deactivated to cease venting such that a predetermined portion of the air contained in the brake engine is vented thereby priming the brake engine.

11. The method according to claim 10 wherein upon the completion of the predetermined time the priming valve disconnects port A from B causing the remaining air to pass through a second valve, the second valve having three ports A, B and C of which ports A and B are straight through ports and ports B and C are cross over ports and the port C
communicating with the exterior of the system.

12. The method according to claim 10 wherein at least one of the drums is locomoting a conveyance.

13. The method according to claim 11 wherein upon the realization of the emergency stop situation the second valve is de-energized to connect ports A and C to route the air out of the system.

14. The method according to claim 11 wherein upon the realization of an alternative emergency stop situation the second valve is energized to connect ports A and B and causing the air to proceed out through a relief valve out of the system.

15. The method according to claim 11 wherein the second valve is de-energized when the conveyance decelerates below a predetermined valve causing ports A and C of the second valve to be connected.

16. The method according to claim 10 wherein upon the realization of an end zone emergency situation, the first valve is de-energized causing ports A and C to connect and maintaining the priming valve energized.

17. The method according to claim 10 wherein a pinion brake engine is activated upon the realization of an emergency situation.