DESC:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See sections 10 & rule 13)
1. TITLE OF THE INVENTION
AN INDUCTIVE PROXIMITY SWITCH BASED HOIST CUT OFF MECHANISM FOR BP100 PIPE LAYER
2. APPLICANT (S)
NAME NATIONALITY ADDRESS
BEML LIMITED IN BEML Soudha, No 23/1, 4th Main S.R. Nagar, Bengaluru- 560027, Karnataka, India.
3. PREAMBLE TO THE DESCRIPTION
COMPLETE SPECIFICATION

The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION:
[001] The present invention relates to the field of electro hydraulic control application. The present invention in particular relates to the inductive proximity switch based hoist cut off mechanism for BP100 pipe layer.
DESCRIPTION OF THE RELATED ART:
[002] Pipe layer is off-highway equipment used for operation in pipeline laying projects, construction sites and in open cast mines for conveyor track shifting etc... Pipe layers are equipped with a heavy duty hoist mechanism which will be used for lifting & carrying the material using sheave block. The bottom sheave of the block can be lowered/ raised at two speeds viz 4.5m/min and 7.5m/min through wire ropes driven by hydraulic winches. The main function of the pipe layer is to handle a load at different hoist positions and carry it over long distances in the uneven and different terrain mine sites. The machine is fitted with side boom & the load is held firmly by the bottom sheave attached with crane hook with ref to top sheave, by maintaining load position through hoist winch.
[003] While lifting of the load, it is necessary to restrict the hoist movement of the bottom sheave at safer position, when it is detected by inductive proximity switch, to avoid damage of the rope, sheave block and boom otherwise.
[004] Reference may be made to the following:
[005] Publication No. 1086/KOL/2011 relates to an inductive proximity switch for detecting the presence of an object in a monitored area, comprising a coil, a pulse source for supplying said coil with transmitting current pulses (Si, 52, S3) at a period (T) larger than the duration (Ts) of said transmitting current pulses, and a processing circuit for generating an output signal based on received voltages (Ui1, U12, U13) varying in dependence of a change of position of the object, said received voltages being induced in said coil after the duration (Ts) of a transmitting current pulse by the decaying current which previously flows in the object due to the voltage induced therein by said coil, characterized in that a suppression circuit is provided for suppressing a signal duration lower than a predetermined perturbation time (Tc1, Tc2) in said output signal such that the minimum time interval between two variations of said output signal does not go below said perturbation time (Tc1, Tc2), wherein said processing circuit is configured to generate an intermediate signal comprising two signal states and to feed said intermediate signal to said suppression circuit to generate said output signal, and wherein said suppression comprises at least one delay circuit for delaying the intermediate signal by the duration of said perturbation time (Tc1, Tc2) for each of said signal states.
[006] This is about various components used in making of inductive proximity switch.
[007] Publication No. US2012062242 relates to an inductive proximity switch for detecting the presence of an object in a monitored area includes a coil, a pulse source for supplying the coil with transmitting current pulses (S1, S2, S3) at a period (T) larger than the duration (Ts) of the transmitting current pulses, and a processing circuit for generating an output signal based on received voltages (Ui1, Ui2, Ui3) varying in dependence of a change of position of the object. The received voltages are induced in the coil after the duration (Ts) of a transmitting current pulse by the decaying current which previously flows in the object due to the voltage induced therein by the coil.
[008] This is about various components used in making of inductive proximity switch.
[009] Publication No. CN207482910 relates to a height measuring device of hacking machine, including installing sensor, positioner and the inductive switch at the frame top, the sensor is ultrasonic distance measuring sensor, positioner installs on ground, and is located the sensor under, positioner includes L die bed seat and buffing pad that two symmetries set up, leaves the distance between two L die bed seats, the buffing pad includes four cleats, stopper, the cleat is made by elastic material, installs respectively in four bights of two L die bed seats, the stopper top is provided with two bench rank, position step site in stopper inboard low relatively, the height of step is a little less than the cleat, inductive switch is proximity switch, installs on L die bed seat for detect L die bed seat top, read the magazine height, convenient to use, the location is accurate.
[010] This is a height measuring system in hacking machine where as our application is hoist sensing mechanism in a pipe layer.
[011] Publication No. CN104521142 relates to inductive proximity switch comprising an oscillator and a transmitter coil for generating an alternating magnetic field, a receiving circuit comprising two receiving coils and operating in differential connection for detecting a metallic trigger, wherein the receiving coils and are arranged such that they can be influenced differently by the trigger and the induced receiving voltages cancel one another out when the trigger is at a desired switching distance.
[012] This is about various components used in making of inductive proximity switch.
[013] Publication No. US2020287541 relates to an inductive proximity switch. The object of the invention to present a very simplified inductive position sensor, which can be reliably used for detecting a zero crossing of its output voltage when a target moves by will be solved by an inductive proximity switch comprising a transmitter coil, a receiver coil, an integrated circuit for excitation of the transmitter coil and a signal processing unit for processing a received signal from the receiver coil, wherein an oscillator excites a resonant circuit comprising the transmitter coil and a parallel capacitor for inducing a voltage in the receiver coil, wherein the receiver coil comprises two symmetrical segments with opposite orientation that are connected in series, wherein the transmitter coil surrounds the segments of the receiver coil or the transmitter coil is surrounded by the segments of the receiver coil.
[014] This is about various components used in making of inductive proximity switch.
[015] Publication No. US5264733 relates to an inductive proximity switch contains an oscillator that generates an alternating magnetic field and which, when a trigger penetrates the alternating field, changes its oscillating state. An evaluation circuit uses the change in state to generate a switching signal to control a load switch. To achieve a proximity switch response distance that is as large as possible regardless of the trigger material and the ambient temperature, two sensing coils are located in the alternating field to detect the difference between voltages induced in them. This is about various components used in making of inductive proximity switch.
[016] While lifting of the load by pipe layer equipment, it is necessary to restrict the hoist movement of the bottom sheave at safer position, when it is detected by inductive proximity switch, to avoid damage of the rope, sheave block and boom otherwise.
[017] When bottom sheave when it is under hoist movement with material, it is likely to hit with impact to top sheave resulting into possible structural damages, as operator may operate hoist mechanism continuously by regular practice.
[018] The existing hoist control mechanism available with standard suppliers is with a limit switch actuated through a hanging dead weight. The hoisting bottom sheave lifts up the dead weight causing the limit switch contacts to operate and responsible for cutting OFF of electrical solenoid bringing hoist movement to stop condition. In this type of mechanism, hanging dead weight gets entangled with the hoist rope with the dead weight coming in between the sheaves causing hitting impact and distortion in load being held vertically. Fig 4 depicts limit switch with hanging dead weight.
[019] In order to overcome above listed prior art, the present invention aims to provide automatic cutting OFF of hoist movement after crossing the safe hoist distance without operator intervention, by using inductive proximity switch. The present invention restricts the hoist from rising beyond specified position using inductive proximity switch placed strategically in the top sheave, which upon sensing bottom sheave position, cuts OFF hydraulic energy to stop further movement of the bottom sheave.
OBJECTS OF THE INVENTION:
[020] The principal object of the present invention is to provide inductive proximity switch based hoist cut off mechanism for BP100 pipe layer.
[021] Another object of the present invention is to provide inductive proximity switch which restricts the hoist from rising beyond specified position using inductive proximity switch placed strategically in the top sheave, which upon sensing bottom sheave position, cuts OFF hydraulic energy to stop further movement of the bottom sheave.
[022] Another object of the present invention is to overcome the issue faced with limit switch based hoist cut OFF mechanism with hanging dead weight.
[023] At the outset of the description that follows, it is to be understood that the ensuing description only illustrates a particular form of this invention. However, such a particular form is only an exemplary embodiment and is not intended to be taken restrictively to imply any limitation on the scope of the present invention.
SUMMARY:
[024] The present invention relates to the inductive proximity switch based hoist cut off mechanism for BP100 pipe layer. The present invention restricts the hoist from rising beyond specified position using inductive proximity switch placed strategically in the top sheave, which upon sensing bottom sheave position, cuts OFF hydraulic energy to stop further movement of the bottom sheave.
[025] The inductive proximity switch of optimum sensing distance is selected so as the bottom sheave being hoisted with maximum speed shall necessarily get stopped without hitting the top sheave.
[026] The inductive proximity switch detects the approaching bottom sheave during hoisting. Wiring is used to inter connect inductive proximity switch, electrical solenoid, control relay and hoist warning indicator. Electrical solenoid is used to cut OFF hydraulic oil flow to hoist winch. It causes hoisting and lowering of bottom sheave through mechanism.
BREIF DESCRIPTION OF THE INVENTION
[027] It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments.
[028] Figure 1- 4 shows inductive proximity switch based hoist cut off mechanism for BP100 pipe layer according to the present invention.
[029] Figure 5 shows Functional block diagram represents hoist control mechanism.
[030] Figure 6 depicts the flow chart of the hoist control system.
[031] Figure 7 indicates the signal that is triggered by Proximity switch.
DETAILED DESCRIPTION OF THE INVENTION:
[032] The present invention provides inductive proximity switch based hoist cut off mechanism for BP100 pipe layer. The present invention restricts the hoist from rising beyond specified position using inductive proximity switch placed strategically in the top sheave, which upon sensing bottom sheave position, cuts OFF hydraulic energy to stop further movement of the bottom sheave.
[033] The inductive proximity switch of optimum sensing distance is selected so as the bottom sheave being hoisted with maximum speed shall necessarily get stopped without hitting the top sheave.
[034] The inductive proximity switch detects the approaching bottom sheave during hoisting. Wiring is used to inter connect inductive proximity switch, electrical solenoid, control relay and hoist warning indicator. Electrical solenoid is used to cut OFF hydraulic oil flow to hoist winch. It causes hoisting and lowering of bottom sheave through mechanism.
[035] In the fig1, the system comprises bottom sheave at fully hoist/raised position 1a, bottom sheave at lowered position 1b, top sheave 2, winch assy- Hoist 3, inductive Proximity switch 4. In the operation of pipe layer, it is necessary to restrict the hoisting beyond the specified position for safety reasons. A mechanism of the invention is to inhibit hoisting beyond the specified movement which is of simple and inexpensive construction and to be readily applicable to existing machine.
[036] In the fig.2, Inductive proximity switch (4) is engineered at bottom surface of top sheave (2) in the metallic cavity which protects the switch in case the bottom sheave (1) hits in worst possible scenario. Material being hoisted by operator at a safe position to carry and place in a different location, sometimes it causes the bottom sheave (1) come closer to top sheave (2) based on material dimensions being carried. Bottom sheave (1) during movement, comes with in sensing distance of about 40mm, the inductive proximity switch (4) energizes control relay which in turn cause electrical cut OFF solenoid (5) to energize to cut OFF hydraulic flow to hoist winch (3) bringing hoist movement to stop condition. Further an audio & visual alarm available in operator console will turn ON for indication of operator that hoist is reached maximum height. The time taken by the inductive proximity switch to detect the bottom sheave is as follows-
a. When bottom sheave is raised at minimum speed:
Min speed of the bottom sheave: 75mm/sec
Max sensing gap of inductive proximity switch: 40mm
Time taken by bottom sheave to travel a distance of 40mm: 0.533 sec
b. When bottom sheave is raised at maximum speed
Min speed of the bottom sheave: 120mm/sec
Max sensing gap of inductive proximity switch: 40mm
Time taken by bottom sheave to travel a distance of 40mm: 0.333 sec
[037] Thus inductive proximity switch with 40mm sensing distance selected is a best suited sensing device to detect, energize the relay which in turn cuts OFF the solenoid which in turn stops the movement of bottom sheave, thereby bringing hoist movement to stop within duration of 0.26sec.
[038] Thus in either of the condition mechanism is able to cut OFF hoist movement safely with reliability.
[039] The novel approach is usage of inductive proximity switch for contact less sensing of approaching bottom sheave, which avoids physical movement of dangling dead weight. The dangling dead weight gets entangled with winch rope and becomes non-responsive. Dangling dead weight also poses problem to personnel working below during loading/unloading of material. Dead weight is likely to fall down due to work loosening of D shackle responsible for holding it. Fig 4 depicts limit switch with hanging dead weight.
[040] The inductive proximity switch is in a strategic position and protection to it ensures the switch never gets damaged. The inductive proximity switch on the top sheave inside the open enclosure which protects switch even if the bottom sheave hits top sheave accidentally in the event proximity switch failures/ malfunction.
[041] Thus selection of inductive proximity switch for the application with required nominal sensing distance. Engineering of the inductive proximity switch in top sheave to avert any physical damages to system is the invention.
[042] Functional block diagram (fig 5) represents hoist control mechanism. When Power supply [201] is given to proximity switch [203], then it becomes ready. Proximity switch [203] is mounted in bottom surface of upper sheave. As and when bottom sheave [202] is approaching proximity switch [203] by operator during material being lifted with hoisting speed of 120mm/sec and when bottom sheave [202] comes within 40mm sensing distance then proximity switch [203] senses the bottom sheave [203] there after energizing the relay [204] which in turn closes its NO contact to energize hoist cut OFF solenoid [205] valve and thus stops the further hoisting of bottom sheave.
[043] Fig. 6 depicts the flow chart of the hoist control system. From the fig 7, 101 indicates the signal that is triggered by Proximity switch when bottom sheave moved up towards proximity switch and is sensed by proximity switch. 102 indicates the signal that the hoist cut OFF solenoid is actuated, cutting OFF the hoist movement further. The time difference between the two actions is 260 ms which is well below the actual time available for cut OFF i.e., 333ms. Thus, we claim that the switch response is fast enough to stop the movement of bottom sheave at a safer distance and thus safe guarding bottom sheave & upper sheave from collision impact otherwise.
[044] Numerous modifications and adaptations of the system of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the true spirit and scope of this invention.
,CLAIMS:WE CLAIM:
1. An inductive proximity switch based hoist cut off mechanism for BP100 pipe layer comprises bottom sheave at fully hoist/raised position (1a), bottom sheave at lowered position (1b), top sheave (2), winch assembly- Hoist (3), inductive Proximity switch (4) engineered at bottom surface of top sheave (2) in the metallic cavity which protects the switch in case the bottom sheave (1) hits in worst possible scenario.
2. The inductive proximity switch based hoist cut off mechanism for BP100 pipe layer, as claimed in claim 1, wherein the material being hoisted by operator at a safe position to carry and place in a different location, sometimes it causes the bottom sheave (1) come closer to top sheave (2) based on material dimensions being carried. Bottom sheave (1) during movement, comes with in sensing distance of about 40mm, the inductive proximity switch (4) energizes control relay which in turn cause electrical cut OFF solenoid (5) to energize to cut OFF hydraulic flow to hoist winch (3) bringing hoist movement to stop condition and an audio & visual alarm available in operator console will turn ON for indication of operator that hoist is reached maximum height.
3. The inductive proximity switch based hoist cut off mechanism for BP100 pipe layer, as claimed in claim 1, wherein the method inhibits hoisting beyond the specified movement which is of simple and inexpensive construction and to be readily applicable to existing machine.

4. The inductive proximity switch based hoist cut off mechanism for BP100 pipe layer, as claimed in claim 1, wherein when bottom sheave is raised at minimum speed; min speed of the bottom sheave 75mm/sec and max sensing gap of inductive proximity switch 40mm, time taken by bottom sheave to travel a distance of 40mm: 0.533 sec.
5. The inductive proximity switch based hoist cut off mechanism for BP100 pipe layer, as claimed in claim 1, wherein when bottom sheave is raised at maximum speed min speed of the bottom sheave 120mm/sec and max sensing gap of inductive proximity switch 40mm, time taken by bottom sheave to travel a distance of 40mm: 0.333 sec.
6. The inductive proximity switch based hoist cut off mechanism for BP100 pipe layer, as claimed in claim 1, wherein inductive proximity switch with 40mm sensing distance detects, energizes the relay which in turn cuts OFF the solenoid which in turn stops the movement of bottom sheave, thereby bringing hoist movement to stop within duration of 0.26 sec.