Complete specification Surface miner cutter start-up aid

Field of Invention:

The present invention relates to an improvement in the power transmission drive line of the surface mining equipments, more particularly the present invention provides an auxiliary start-up aid for the surface mining equipments which aids in reduction of the inertial start up shocks on the prime mover and on the drive line assembly.

Background of the Invention:

Surface miners are equipments or machines which are used to extract minerals from the mine face with a mining tool fixed to a mobile frame. In surface miners the mining tool is attached to the frame and is driven with a drive train connected to a prime mover. In general for surface miner applications the cutter drum has enough energy per weight ratio to store more power than that can actually be generated by the prime mover driving the drum. But there is a limitation on the peripheral speed beyond which the cutting tips wear out exponentially. Because of this the drum speed cannot be increased beyond a certain limit and hence the inertial energy that can be stored in the cutter drum is limited.

Due to advancements in technology better materials are being developed which are more wear & tear resistant and can take much higher cutting speeds. At higher cutting speeds the productivity of the cutter drum proportionally increases under comparable conditions.

Another advantage in using higher speeds is that it will help in increasing the stored energy of the cutter drum. The energy stored in the drum is proportional to its of about its avis drum.

Even otherwise with existing limitation on the cutter speed we can reasonably raise the bar on the energy storage by seeking to other methods of increasing the inertia like increasing the outer diameter, or decreasing the inner diameter, using denser materials etc. The starting torque required to start the drum also increases as we increase the inertia of the cutter drum or the speed of the drum, and begin to store more energy in the cutter drum. In a combustion engine driven mining equipment generally the cutting drum is connected to the combustion engine via a mechanical clutch arrangement. There are limitations on the clutch on the maximum rpm of engagement which will be around the idle rpm of the engine and the engine cannot produce sufficient torques to overcome starting torques of very high inertial loads. While engagement of any inertial load to the engine, it has to supply energy equivalent to the difference of its energy levels before and after the engagement. Generally when the engagement is complete the cutter drum is expected to be running at equilibrium with respect to the prime mover driving it. In case of huge inertial start up loads this energy difference is very high and engine will die down immediately once such engagement occurs.

Depending on the cutter inertial loads and working loads the prime mover is selected and used. This leads to higher prime mover power requirements in case of high inertial rotary running tool, in other way limits the maximum rotational inertial load that can be engaged to a given prime mover. The engine or prime mover has to be oversized to run the high inertia start up load which will negate the problem statement completely by providing a bigger cutter drum to store maximum possible energy from the oversized prime mover. Even if we increase the inertia of the engine by means of increasing the flywheel size or by increasing the inertia of the internal components, this again has a certain limit beyond which no further increase is possible.

The present invention overcomes all of the above said problems by placing a start up aid in the form of a sacrificial auxiliary drive at any point of the drive line where the power can be efficiently transferred to the cutter drum unit, to provide assistance to the main prime mover in case of starting high inertial loads by reducing the inertial load on the prime mover directly.

Objective of the Invention:

The main objective of the present invention is to provide a start up aid for assisting the main prime mover in case of starting high inertial loads.

The second objective of the present invention is to improve the engine life by lowering the shock loads on the engine or prime mover with the said start up aid.

The third objective of the present invention is to achieve better clutch life by reducing the differential speeds of drive and the driven components.

Another objective of the present invention is to increase the system capacity to take higher inertial start up loads by increasing the clutch engagement rpm.

Brief description of the prior art:

EP1936033B1 relates to the surface treatment machines with a supplemental drive for rotation of a rotor for inspection, maintenance, or testing purposes. The patent also discloses the method of manufacturing a surface treatment machine that includes a drive motor mounted on the chassis; drum rotor coupled to a drive motor and adapting the drive motor to the drive pulley to rotate the drum rotor at a first rotational velocity when the drive motor is activated. Further, the method also includes adapting the service motor to the drive pulley to rotate the drum rotor at a second rotational velocity when the service motor is activated.

US3335622 describes a mining arrangement with auxiliary means for transmitting motion to the drive couple of a mining conveyor mechanism and/or a mining machine displacement mechanism. The auxiliary means includes an auxiliary connecting, auxiliary coupling and drivable auxiliary rotary motion transmitting means, mounted on the conveyor drive of the mining arrangement for auxiliary rotatable driving of the mining conveyor driving drum,

US3435928 discloses an independent hydraulically operated auxiliary drive to automatically connect into a train of gears for operating an auger mining mechanism to preposition the auger drive socket by rotation for the insertion of an auger section. This relates to an auxiliary drive for a fluid operated motor to operate as a clutch to engage with the work or driving load before full operation of the fluid motor.

US20110215634 claims a construction machine for the treatment of ground surfaces comprising a machine frame, a drive motor, a work drum supported from the machine frame and including exchangeable tools fastened to the work drum, a belt drive and an auxiliary drive. The auxiliary drive is coupled to the drive line to rotate the work roller in its raised condition by a predetermined rotational angle to bring the tools into a more convenient mounting position. The torque of the auxiliary drive is slightly higher than the moment of inertia of the work roller and of the drive line moving along with the work roller, thus allowing a rotational movement and keeping the risk of accidents as low as possible. This improved machine construction machine enables an exchange of the tools with reduced expenditure in personnel and time.

US20120298004 relates to a mining vehicle and method for its energy supply. The mining vehicle is provided with a carriage; driving equipment for moving the carriage; one mining work device; one electric motor for operating a main function of the mining vehicle; one electric motor for operating an auxiliary function of the mining vehicle; and a power-generating auxiliary unit. The power-generating auxiliary unit supplies part of the power required by the electric motor operating the auxiliary function.

US20110248654 claims a self-propelled working machine in the form of a surface milling machine, comprising a main operating unit and/ or a drive unit, which is operable in a steady-state operating status and driven by a drive device comprising an electrical motor. The electrical motor is associated with a start-up aid including a frequency converter for the limitation of starting current.

The patent also provides an operating circuit for the steady-state operation comprising a jumper for bridging the frequency converter following starting or reaching steady-state operational status. Optionally, the jumper is switchable to activate or inactivate the frequency converter of the start-up circuit, respectively.

All of the above mentioned auxiliary drives are either employed to rotate the cutting drum unit by a fixed angle or to rotate the cutting drum unit to a particular position, or to operate as a clutch to engage with driving load or to rotate the cutting drum unit by a fixed or variable secondary speed purely for the purposes of inspection, maintenance, or testing purposes like visual observation or for replacing the worn out cutting tips or picks or wedges. The present invention eliminates the drawbacks associated with the existing systems by introducing a start up aid to provide assistance to the main prime mover in case of starting high inertial loads by reducing the inertial load on the prime mover. The start up aid further provides improved engine life by lowering the shock loads on the engine; better clutch life by reducing the differential speeds of drive and driven components; increased system capacity to take higher inertial start up loads.

Summary of the invention:

The present invention provides an start up aid for the surface mining equipment in the form of auxiliary drive mounted at any point of the drive line where the power can be efficiently transferred to the cutter drum unit, to provide assistance to the main prime mover in case of starting high inertial loads by reducing the inertial load on the prime mover. The auxiliary drive of the present invention further improves the engine life by lowering the shock loads on the engine; increases the clutch life by reducing the differential speeds of drive and driven components; increases the system capacity to take higher inertial start up loads by increasing the clutch engagement rpm. The surface rnining equipment with auxiliary start up aid enables to cut hard formations without the problem of cutter stalling due to the availability of higher amount of instantaneously energy.

This energy even when depleted, over a period of time will again get charged up and will be used when needed. Hence a much smaller size of equipment does the jobs of higher class machines with improved machine performance. The auxiliary drive start up aid can also be mounted on the non driven side of the cutter drum. The auxiliary drive start up aid of the present invention not only leads to improved drive train life and but also eliminates the limitation on the maximum inertial load that can be applied to a given prime mover.

Brief description of the drawing:

Fig 1 shows the perspective view of surface mining equipment with auxiliary drive start up aid.

Detailed description of the invention with respect to drawing:

The present invention provides an auxiliary drive mounted at any point of the drive line where the power can be efficiently transferred to the cutter drum unit, to provide assistance to the main prime mover in case of starting high inertial loads by reducing the inertial load on the prime mover. The auxiliary drive of the present invention further improves the engine life by lowering the shock loads on the engine; increases the clutch life by reducing the differential speeds of drive and driven components; increases the system capacity to take higher inertial start up loads by increasing the clutch engagement rpm.

FIG 1 illustrates a surface mining equipment comprising of a hydraulic driven auxiliary drive assembly (17) pivoted through an arm on the mining tool housing (18); prime mover with suitably designed set of moving components; mining tool device (19) mounted and driven accordingly for mechanical extraction of minerals. The said auxiliary drive is engaged to the mechanical drive train (20) using a belt tension arrangement (21).

In surface mining equipment particularly, the mining tool device (19) mounted in the mining tool housing (18) aids in mechanical extraction through its rotation.

The mining tool (19) at the time of rest has to be brought to desired running speeds, by engaging it to an already running prime mover. During the engagement of this rotary inertial load, due to the differential speeds of the drive and driven components an inelastic collision occurs. During this collision, initial angular momentum of the drive and the resultant angular momentum of the system are conserved. The auxiliary drive system (17) of the present invention rotates the mining tool device (19) to a pre-set speed, thereby decreasing the difference in speeds of the drive and the driven components, thus reducing the collision intensity. On the other hand the prime mover does not have linearly varying properties throughout its operating range. Below certain speeds the prime mover cannot develop enough power to sustain its own running. This phenomenon will lead to immediate dying down of the prime mover below certain speed limit; this restricts the maximum inertial load that can be applied on to the prime mover. The auxiliary drive (17) of the present invention not only leads to improved drive train life and but also eliminates the limitation on the maximum inertial load that can be applied to a given prime mover.

In surface miner or any other cutter applications where the cutter can over speed or free wheel, the cutter becomes a huge flywheel battery and can store a lot of energy. The maximum energy that can be stored in a cutter is computed by combining the following expressions:

Tensile stress at its outer radius, due to its spin speed, can be computed from: Tensile Stress = (Rim Density) (Radius)2 * (Spin Speed)2

For practical aspect ratios, it is related to the rim's ID/OD ratio by slightly complicated relationships.


Where, the total volume includes the space inside the rim.

In the preferred embodiment the auxiliary drive start up aid (17) can be mounted on any part or position on the drive line where power can be efficiently transferred to the cutter drum unit.

In the preferred embodiment the auxiliary drive start up aid are preferably in the form of electrical, hydraulic or pneumatic motors.

In the preferred embodiment the auxiliary drive start up aid improves the engine life by lowering the shock loads on the engine which will otherwise be transferred to the engine if high inertial start up load is engaged directly without a start up aid and the auxiliary drive itself acting as a sacrificial member.

In the preferred embodiment the auxiliary drive start up aid avoids an additional personnel engagement for the purpose of manual drum rotation.

In the preferred embodiment the auxiliary drive start up aid used for achieving better clutch life by reducing the differential speeds of drive and driven components. To achieve better clutch life the amount of clutch slippage is reduced during engagement.

In the preferred embodiment the auxiliary drive start up aid increases the clutch engagement rpm by engaging a cutter drum already running at a particular rpm, thus increasing the system capacity to take higher inertial start up loads.

In the preferred embodiment the surface mining equipment can include idlers, main drive and driven pulleys, an extra idler, solely for the purpose of auxiliary powered drive.

In another embodiment a hydraulic motor with suitable control valves are mounted on the clutch toothed gear ring externally by means of friction drive, so that the engine/prime mover in a disconnected state will hydraulically be able to run the hydraulic motor which in turn can drive the driven side of the drive line.

In another embodiment the hydraulic motor can be replaced with electric or pneumatic motors.

In another embodiment a separate hydraulic, electrical or Pneumatic drive are used on the non driven side of the cutter drum which acts as an auxiliary drive.

This surface mining equipment with auxiliary start up aid enables to cut hard formations without the problem of cutter stalling due to the availability of higher amount of instantaneously energy. This energy even when depleted, over a period of time will again get charged up and will be used when needed. But requires a sufficient time interval to charge the rotary cutter drum unit to the required peak or sub peak energy level. Hence a much smaller size of equipment does the jobs of higher class machines with improved machine performance.

The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without departing from the spirit of the present invention.

We Claim:

1) A start up aid for the surface mining equipment in the form of an auxiliary drive, mounted at any point of the drive line, to provide assistance to the main prime mover in case of starting high inertial loads, by reducing the inertial load on the prime mover.

2) As claimed in claim 1, wherein the said auxiliary drive start up aid are preferably electrical, hydraulic or pneumatic motors.

3) As claimed in claim 1, wherein the said auxiliary drive start up aid is mounted on any part or position on the drive line where the power is efficiently transferred to the cutter drum unit.

4) As claimed in claim 1, wherein the said auxiliary drive start up aid enables a smaller size of surface mining equipment without necessarily resizing the engine to a bigger size.

5) As claimed in claim 1, wherein the said auxiliary drive start up aid improves the engine life by lowering the shock loads on the engine.

6) As claimed in claim 1, wherein the said auxiliary drive start up aid is used for achieving better clutch life by reducing the differential speeds of drive and driven components.

7) As claimed in claim 1, wherein the said auxiliary drive start up aid increases the system capacity to take higher inertial start up loads by increasing the clutch engagement rpm.

8) As claimed in claim 1, wherein the said auxiliary drive start up aid enables the surface mining equipment to cut harder formations without the problem of cutter stalling and also enables to store more energy in the high inertial cutter drum.

9) As claimed in claim 1, wherein the said auxiliary drive start up aid eliminates the limitation on the maximum inertial load that can be applied to a prime mover.

10) As claimed in claim 1, wherein the said auxiliary drive start up aid in the form of electrical, hydraulic or pneumatic motors can also be mounted on the non driven side of the cutter drum.

11) As claimed in claim 1, the surface mining equipment can preferably include idlers, main drive and driven pulleys, an extra idler and other drive connections.