Patent Application
20210062651
The present invention relates to a mining dumper and a method for intensifying or boosting a moving of the mining dumper.
Mining dumpers may be used in mines to carry blasted rock or other material for example from an excavation position to a further processing.
A working efficiency of the mining dumper, i.e. an amount of the material to be transported in a certain time period by the mining dumper, is a key factor of the mining dumper for an operator of the mine when selecting the mining dumper to be utilized. The working efficiency is a result of an engine power, i.e. a maximum attainable speed of the mining dumper, and a maximum loading capacity of the mining dumper, i.e. a total weight of the mining dumper. Additionally, especially in underground mines, it must be considered also a physical size of the mining dumper due to limited sizes of tunnels and exhaust gas emissions due to a ventilation need for removing the exhaust gas out of the mine.
In this working efficiency a maximum ramp speed attainable is one of the most important features of the mining dumper because of typically very long uphill sections when the excavated material is transported from the excavation position to the further processing. The ramp speed depends on an angle of ascent of the ramp providing a driveway, a mass of the loaded mining dumper and a tractive effort. The tractive effort is limited by a power available from an engine of the mining dumper through other power transmission components to wheels of the mining dumper.
The mining dumpers are typically equipped with a diesel engine, a size of which limits an engine power available. The engine power, and thereby also the maximum ramp speed available, may be increased by choosing a more powerful engine. This, however, increases also a physical size of the engine and also arouses a need to increase a dimensioning of other components in a power transmission system of the mining dumper and may also arouse a need to totally redesign the mining dumper. Also the exhaust gas emissions will be higher. This increases a need of ventilation in the underground mines, which increases a total energy consumption of underground mining.
WO-publications 2013/113103 A1, 2015/029075 A2 and 2007/081545 A2 and US-publication 4533011 A disclose some embodiments of hybrid vehicles comprising both a combustion engine and an electric motor.
An object of the present invention is to provide a novel mining dumper.
The invention is characterized by the features of the independent claims.
The invention is based on the idea of including at least one electric motor in a power transmission system of the mining dumper in such a way that the electric motor is connected to the drive shaft so that it applies additional power directly to the drive shaft. The additional power provided by the electric motor thus does not go to the drive shaft through the transmission of the power transmission system but directly from the electric motor to the drive shaft and driving axles.
The electric motor may be operated to provide additional power for the mining dumper especially when the mining dumper is moving uphill, the electric motor thus providing an increase of the speed of the mining dumper in the ramp when the mining dumper is driving uphill for example from an excavation position at a lower part of the mine towards an intermediate storage or a further processing being located at an upper part of the mine when compared to a mining dumper not comprising the power transmission system as disclosed herein. Because the additional power provided by the electric motor is applied directly or straight to the drive shaft and the driving axles, and not through the transmission at all, the transmission is not burdened by the additional power of the electric motor. The transmission thus does not need to be dimensioned to withstand the additional power provided by the electric motor.
Some embodiments of the invention are disclosed in the dependent claims.
In the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which
For the sake of clarity, the figures show some embodiments of the invention in a simplified manner. Like reference numerals identify like elements in the figures.
The mining dumper 1 of
On top of the front frame 2a there is a cabin 6 for an operator of the dumper 1. If the mining dumper is an autonomously operated mining dumper, or if the mining dumper is a semi-autonomously operated mining dumper, which is operated through a remote access, the cabin 6 may be omitted.
On a top part of the front chassis 2a there is also an engine compartment 7 for a combustion engine of the dumper 1. The combustion engine is typically a diesel engine. In a mining dumper with a 63 tons payload there is a diesel engine with a 16 litres capacity having a maximum power output of 565 kW.
On a top of the rear frame 2b there is a dump box 8 as well as necessary means for tipping the dump box 8 for unloading the mining dumper 1.
The power transmission system 9 further comprises an electric motor 15. The electric motor 15 is connected to the drive shaft 12 for applying additional power to the drive shaft 12. The electric motor 15 is connected to the drive shaft 12 in such a way that the additional power provided by the electric motor 15 is applied directly or straight to the drive shaft 12, whereby the additional power provided by the electric motor 15 does not go to the drive shaft 12 through the transmission 11. The electric motor 15 may for example be a permanent magnet motor.
In the embodiment of
In another possible embodiment the electric motor 15 comprises an axis of its own and a gearwheel attached to that axis. The drive shaft 12, in turn, comprises another gearwheel which is arranged in connection with the gearwheel in the axis of the electric motor 15 so as to transmit the additional power provided by the electric motor 15 to the drive shaft 12. In other words it may be said that there is a gear transmission between the electric motor 15 and the drive shaft 12.
The power transmission system 9 further comprises a battery pack 16 for supplying electric energy to the electric motor 15. Between the electric motor 15 and the battery pack 16 there is a current director element 19 that is used in controlling the operation of the electric motor 15. The battery pack 16 is connected to the current director element 19 with the first electric power line 17 and the current director element 19 is connected to the electric motor 15 with the second electric power line 18.
The battery pack 16 comprises a number of rechargeable batteries. In the battery pack 16 of
The current director element 19 may be an inverter device, i.e. an inverter, that comprises inverter means for converting direct current supplied by the battery pack 16 to alternating current suitable for operating the electric motor 15 as well as rectifier means for converting alternating current to direct current suitable for recharging the rechargeable batteries 16a, 16b, 16c, 16d in the battery pack 16.
The battery pack 16 provides one kind of an energy storing device for supplying electric energy to the electric motor 15. Other kind of energy storing devices, such as supercapasitors, may also be utilized.
The mining dumper 1 further comprises a control unit 20. The control unit 20 is connected to the current director element 19. The control unit 20 is intended to control the operation of the current director element 19, whereby the control unit 20 may be used to control the operation of the electric motor 15 by controlling the operation of the current director element 19. The control unit 20 may also be an integral part of the current director element 19 or the current director element 19 may be an integral part of the control unit 20.
The electric motor 15 is intended to be operated for providing additional power for the mining dumper especially when the mining dumper is moving uphill, whereby a ramp speed of the mining dumper 1 can be increased when compared to a mining dumper not comprising the power transmission system as disclosed herein. To be more precise, the electric motor 15 is intended to provide additional torque that is applied directly or straight to the drive shaft 12 without substantially affecting on the rotation speed of the drive shaft 12. Due to this additional torque a driving speed of the mining dumper 1 does not decrease from a driving speed of a flat country as much as it does with mining dumpers not comprising the power transmission system as disclosed herein, when the mining dumper 1 is driving uphill. The amount of the decrease in the driving speed of the mining dumper 1 is dependent on the maximum power output available from the electric motor 15 and an amount of the power output that is provided from the electric motor 15 in each case is not necessarily the same as the maximum power output of the electric motor 15.
The control unit 20 may be configured to start the operation of the electric motor 15 automatically in response to the mining dumper 1 entering to the ramp or the uphill section. Entering of the mining dumper 1 to the ramp or uphill section may for example be detected by an acceleration sensor or inclination sensor. Alternatively the operator of the mining dumper 1 may start the operation of the electric motor 15 when the mining dumper 1 enters to the ramp or the uphill section.
The additional power provided by the electric motor 15 may also be utilized during accelerations of the mining dumper 1, such as during starting of the loaded mining dumper 1.
Because the additional power provided by the electric motor 15 is applied directly or straight to the drive shaft 12, and not through the transmission 11 at all, the transmission 11 is not burdened by the additional power of the electric motor 15. The transmission 11 may thus be substantially maintained as it is, only slight modification in connection between the transmission 11 and the drive shaft 12 may be needed if the drive shaft 12 currently available is not dimensioned to withstand the additional torque provided by the electric motor 15 and must therefore be replaced. Similarly, the driving axles 13, 14 as well as their connections to the drive shaft 12 and to the wheels 4, 5 must be replaced only if they are not dimensioned to withstand the additional torque provided by the electric motor 15. The combustion engine 10, the transmission 11 and the general structure of the power transmission system 9 may thus be maintained as they are. The additional power to the mining dumper 1 is also provided in a form which does not increase exhaust gas emissions in the mine.
In the following the operation of different embodiments are further investigated in more detail.
According to an embodiment the operation of the electric motor 15 is controlled by the current director element 19 for example on a basis of a torque control principle. Other control methods are applicable also. The inverter and power electronics thereon can utilize conventional control methods of the electric motor depending on the motor type. These control methods have not been disclosed herein in more detail because they are generally known for a person skilled in the art of electric motor control techniques.
According to an embodiment the mining dumper 1 comprises at least one sensor 21 for measuring a rotational speed RS of the drive shaft 12. The measured rotational speed RS of the drive shaft 12 is received by the control unit 20 and forwarded by the control unit 20 to the current director element 19, unless the measured rotational speed RS of the drive shaft 12 is not transmitted directly to the current director element 19. The current director element 19 controls the operation of the electric motor 15 on the basis of the measured rotational speed RS and a given reference received from a control system of the mining dumper 1 so that the electric motor 15 may apply to the drive shaft 12 the needed torque to provide better performance. In this embodiment the control principle of the current director element 19 may be based for example on the Pulse Width Modulation (PWM) control technique or on a vector control technique. These control techniques are substantially known for a person skilled in the art of electric motor controls and are not disclosed herein in more detail.
Referring back to the above mentioned mining dumper of 63 tons payload and having an engine with the maximum power output of 565 kW, the electric motor 15 may for example be a permanent magnet motor of 200 kW. In an uphill having an angle of ascent 1:7 the combustion engine provides a speed of about 9.5 km/h with a full load. The rotational speed of the drive shaft is then about 1000 rpm. With this rotational speed of the drive shaft the maximum torque of the electric motor is about 1700 Nm, the output power of the electric motor being at this operating point about 180 kW. This additional power raises the speed of the mining dumper in the uphill driving from that of about 9.5 km/h to about 13.5 km/h in the uphill having the angle of ascent of 1:7 with the full load. With this speed increase a driving time in 4000 metres long uphill is reduced by seven and half minutes. This means about 10% increase in a total hoisting capacity although it has also been taken into account that the maximum load capacity of the dumper has to be reduced from 63 tons to 60 tons because of the additional weight and space requirement of the battery pack 16.
In order the electric motor 15 being able to apply additional power for moving the mining dumper 1, there must of course be electrical power available in the battery pack 16. It can be considered at least the following alternatives for ensuring, that there is electrical power available in the battery pack 16.
According to an embodiment the entire battery pack 16 or a number of rechargeable batteries 16a, 16b, 16c, 16d in the battery pack 16 not containing any or enough charging is replaced with another battery pack or another rechargeable batteries 16a, 16b, 16c, 16d that are full of charging. In this case the rechargeable batteries 16a, 16b, 16c, 16d in the battery pack 16 can be recharged in a recharging station that is separate from the mining dumper 1. The replacement of the rechargeable batteries 16a, 16b, 16c, 16d being out of charging may be carried out for example during loading the mining dumper 1 or before or after it.
According to an alternative embodiment the electric motor 15 is arranged to be operated as a generator for recharging the at least one rechargeable battery 16a, 16b, 16c, 16d during an engine braking of the mining dumper 1. This embodiment allows the rechargeable batteries 16a, 16b, 16c, 16d to be recharged when the mining dumper 1 is for example moving downhill back towards the excavating position after carrying the load uphill to the intermediate storage or to the further processing. The electric motor 15 is thus utilized to recapture energy with regenerative braking.
According to another alternative embodiment the mining dumper 1 comprises at least one charging circuit 22 connectable to an electric power source external to the mining dumper 1 for recharging the at least one rechargeable battery 16a, 16b, 16c, 16d in the battery pack 16. If the external electric power source is an alternating current source, a charging current CC provided by the charging circuit 22 may be supplied to the rechargeable batteries 16a, 16b, 16c, 16d in the battery pack 16 through the current direction element 19.
In a further alternative embodiment of the mining dumper 1, as disclosed in
At least some of the different embodiments disclosed above for recharging the rechargeable batteries may also be combined with each other in a single mining dumper.
The number of the rechargeable batteries in the battery pack 16 may be arranged to be scalable relative to an intended increase and duration of additional power provided by the electric motor. In the example disclosed in the Figures the battery pack 16 comprises four rechargeable batteries 16a, 16b, 16c, 16d which may or may not have the same storage capacity. A combination of a number of rechargeable batteries having same or different storage capacity is selected depending on the intended increase and duration of additional power provided by the electric motor 15.
According to an embodiment a single rechargeable battery 16a, 16b, 16c, 16d may have a storage capacity of 24 kWh. With a battery pack comprising two rechargeable batteries with the storage capacity of 24 kWh each the 200 kW electric motor is able to provide additional power for about 11 minutes with full power and about 23 minutes with half power. With a battery pack comprising four rechargeable batteries with the storage capacity of 24 kWh the 200 kW electric motor is able to provide additional power for about 23 minutes with full power, which is enough for 5000 metres long uphill with the angle of ascent of 1:7.
The battery pack 16 may be arranged in the mining dumper 1 at various positions, as schematically disclosed in
It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 17189390.2 | Sep 2017 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/073790 | 9/5/2018 | WO | 00 |
