TECHNICAL FIELD
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The present application relates to an underground mining vehicle comprising a load carrying element and a method for controlling an operation of an underground mining vehicle comprising a load carrying element.
BACKGROUND
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Underground mining vehicles comprising a load carrying element are heavy duty work machines, including typically different kind of loaders and dump trucks.
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The loaders are typically used to load crushed rock for onward transport. Sometimes the loaders can also be used to transport the crushed rock from a loading site in an underground mine to an unloading site inside or outside the underground mine. For carrying the crushed rock, the loader comprises a lift arm and a bucket coupled to the lift arm. The bucket forms the load carrying element of the loader.
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The dump trucks are used to transport the crushed rock from a loading site in an underground mine to an unloading site inside or outside the underground mine. For carrying the crushed rock, the dump truck comprises a dump box mounted on a body of the dump truck. The dump box forms the load carrying element of the dump truck.
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Due to the intended use of the underground mining vehicles, the vehicles themselves, as well as parts of the vehicles, such as the lift arm, the bucket and the dump box, are heavy. This means that forces intended to operate the parts of the underground mining vehicles are high, even without any payload, i.e., the crushed rock, carried in the bucket or the dump box. The forces necessary to operate the parts of the underground mining vehicles further increase with the payload.
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Due to the high forces needed to operate the parts of the underground mining vehicles, these parts are typically operated with hydraulic operating circuits. The operation of the part typically includes a movement of the part of the vehicle relative to some other part of the vehicle. This movement may include either a linear motion of the part, or a rotation of the part about at least one joint in the vehicle, or some combination of these movements. The movements are often implemented by using hydraulic cylinders.
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For an efficient operation of the underground mining vehicle, speeds of the movements of the parts of the underground mining vehicle are usually quite high. When it comes to the hydraulic operating circuits comprising hydraulic cylinders, this means that the speeds of motions of the hydraulic cylinders are also high. For prolonging a service life of the hydraulic cylinders and the respective parts of the underground mining vehicle, the hydraulic cylinders may be provided with an end cushioning. The end cushioning is used to reduce shocks against a cylinder head by reducing a kinetic energy of a piston of the cylinder at an end of a stroke of the piston.
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There is a need for an improved cushioning effect implementation in the operation of the load carrying element in the underground mining vehicles.
SUMMARY
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The present application provides an example of an underground mining vehicle and a method for controlling an operation of the underground mining vehicle with an improved cushioning effect implementation for a hydraulic cylinder in a hydraulic operating circuit of the underground mining vehicle.
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The underground mining vehicle comprises a load carrying element, a hydraulic operating circuit comprising at least one hydraulic cylinder for operating the load carrying element and a control system for controlling an operation of the hydraulic operating circuit, wherein the control system comprises at least one data acquisition device for collecting operational data representing an operation of the at least one of the hydraulic operating circuit and the at least one hydraulic cylinder, and a control unit configured to control the operation of the hydraulic operating circuit to control, based on the collected operational data, a speed of motion of the at least one hydraulic cylinder for providing a controllable cushioning effect for the at least one hydraulic cylinder.
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The method is related to controlling an operation of an underground mining vehicle, wherein the underground mining vehicle comprises a hydraulic operating circuit comprising at least one hydraulic cylinder for operating a load carrying element of the underground mining vehicle and the method comprises collecting operational data representing an operation of the at least one of the hydraulic operating circuit and the at least one hydraulic cylinder, and controlling the operation of the hydraulic operating circuit to control, based on the collected operational data, a speed of motion of the at least one hydraulic cylinder for providing a controllable cushioning effect for the at least one hydraulic cylinder.
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The present application is based on the idea of monitoring at least one of the operation of the hydraulic operating circuit and the operation of the at least one hydraulic cylinder in the hydraulic operating circuit. The speed of motion of the at least one hydraulic cylinder may then be controlled, based on that monitoring, for providing the controllable cushioning effect for the operation of the at least one hydraulic cylinder. The controlled cushioning effect may for example be provided at the end of the stroke of the piston to reduce shocks against the cylinder head by reducing the kinetic energy of the piston of the cylinder at the end of the stroke of the piston. However, the controlled cushioning effect may be provided at any point of the stroke of the piston to reduce possible shocks that may occur when the stroke of the piston is stopped.
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An advantage of the solution of the present application is a controllable cushioning effect for the hydraulic cylinder by controlling the speed of motion of the at least one hydraulic cylinder based on the monitoring of at least one of the operation of the hydraulic operating circuit and the operation of the at least one hydraulic cylinder in the hydraulic operating circuit. The efficiency of the cushioning effect may thus be varied according to the operational state of the hydraulic operating circuit. Alternatively, the efficiency of the end cushioning may be varied according to the operational state of the at least one hydraulic cylinder in the hydraulic operating circuit. The efficiency of the end cushioning may also be varied both according to the operational state of the hydraulic operating circuit and according to the operational state of the at least one hydraulic cylinder in the hydraulic operating circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
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In the following the present application will be described in greater detail by means of example embodiments with reference to the accompanying drawings, in which
- Figure 1 shows schematically a side view of an underground mining loader;
- Figure 2 shows schematically a side view of a lift arm and a bucket of an underground mining loader;
- Figure 3 shows schematically an underground mining dump truck;
- Figure 4 shows schematically a basic construction of a hydraulic operating circuit in an underground mining vehicle;
- Figure 5 shows schematically a method for controlling an operation of an underground mining vehicle;
- Figure 6 shows schematically an example embodiment of a hydraulic operating circuit in an underground mining vehicle;
- Figure 7 shows schematically a second example embodiment of a hydraulic operating circuit in an underground mining vehicle, and
- Figure 8 shows schematically a third example embodiment of a hydraulic operating circuit in an underground mining vehicle.
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For the sake of clarity, the figures show some example embodiments of the present application in a simplified manner. Like reference numerals identify like elements in the figures.
DETAILED DESCRIPTION
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Figure 1 shows schematically a side view of an underground mining loader 1. The loader 1 comprises a first subframe 2a and a second subframe 2b. The first subframe 2a and the second subframe 2b are coupled to each other with a middle joint 3. The loader 1 is thus an articulated underground mining loader.
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In the example embodiment of Figure 1, the first subframe 2a is intended to carry a power source of the loader 1. The second subframe 2b, in turn, is intended to carry a load carrying element of the loader 1, i.e., a bucket 4. The bucket 4 is coupled to the second subframe 2b by a lift arm 5. The lift arm 5 is operated by a hydraulic lift cylinder 6. The lift arm 5 and the bucket 4 coupled to the lift arm 5 may be lifted and lowered by operating the lift cylinder 6. The bucket 4 is operated by a hydraulic tilt cylinder 7. It can be connected directly to the bucket 4 or via linkage. The position of the bucket 4 may be changed by operating the tilt cylinder 7.
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Figure 2 shows schematically a side view of another lift arm 5 and of another bucket 4 coupled to the lift arm 5. Figure 2 further shows a tilt cylinder 7. A first end E1 of the tilt cylinder 7 is connected to the second subframe 2b at a first bracket 8 in the lift arm 5 and a second end E2 of the tilt cylinder 7 is connected to a first part of a z-linkage. A joint 10 forms a pivot point, in relation to which the bucket 4 changes its position as a response to the operation of the tilt cylinder 7. Figure 2 further shows schematically a connecting rod 11 between a swing lever and the bucket 4.
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In the example embodiment of Figure 2, the bucket 4 further comprises a first wear part 12 at a lip portion of the bucket 4. There may be more than just one wear part 12 at the lip portion of the bucket 4. Furthermore, the bucket 4 comprises a second wear part 13 at lower side portion of the bucket 4. There may be more than just one wear part 13 at both side portions of the bucket 4. The first 12 and second 13 wear parts are also called ground engaging tools. The ground engaging tools are typically replaceable. The ground engaging tools are the parts of the bucket 4 that are especially intended to contact the ground when the bucket 4 is in use.
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Figure 3 shows schematically an underground mining dump truck 15. The dump truck 15 comprises a first subframe 2a and a second subframe 2b. The first subframe 2a and the second subframe 2b are coupled to each other with a middle joint 3. The dump truck 15 is thus an articulated underground mining dump truck.
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In the example embodiment of Figure 3, the first subframe 2a is intended to carry a load carrying element of the dump truck 15, i.e., a dump box 16. The second subframe 2b, in turn, is intended to carry a power source of the dump truck 15. The dump box 16 is coupled to the first subframe 2a by a joint 17. The dump box 16 is operated by one or more hydraulic lift cylinders 18, the example embodiment of Figure 3 comprising two lift cylinders 18 one of which is invisible on the other side of the dump truck 15. The dump box 16 may be lifted and lowered by operating the lift cylinders 18.
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Figure 4 shows schematically an example embodiment of a basic construction of a hydraulic operating circuit 20 in an underground mining vehicle. The hydraulic operating circuit 20 comprises a hydraulic cylinder 21 provided with a movable piston 22. The piston 22 comprises a piston rod 22a. The hydraulic cylinder 21 may correspond any hydraulic cylinder that is intended to operate at least one part of the underground mining vehicle in relation to at least one joint in the underground mining vehicle. Depending on the type of the joint, the operation of the hydraulic cylinder may provide either a linear or rotational movement of the part joined by the joint.
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Referring to the example embodiment of Figure 1, the part to be operated by the hydraulic cylinder 21 is the bucket 4 of the loader 1. In that case, the hydraulic cylinder 21 of Figure 4 is the tilt cylinder 7 of the bucket 4. The tilt cylinder 7 is intended to operate the bucket 4 to turn about the joint 10.
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According to an alternative, the part to be operated by the hydraulic cylinder 21 is the lift arm 5 of the loader 1. In that case, the hydraulic cylinder 21 of Figure 4 is the lift cylinder 6 of the lift arm 5 of the loader 1.
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According to a further alternative, the part to be operated by the hydraulic cylinder 21 is the dump box 16 of the dump truck 15. In that case, the hydraulic cylinder 21 of Figure 4 is the lift cylinder 18 of the dump truck 15. The lift cylinders 18 are intended to operate the dump box 16 to turn about the joint 17.
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The hydraulic operating circuit 20 further comprises a flow control valve 23 for controlling the operation of the hydraulic operating circuit 20. The flow control valve 23 is configured to control a flow of hydraulic pressure fluid into and out of the hydraulic cylinder 21. The control of the operation of the hydraulic operating circuit 20 can include a control of a direction of motion of the hydraulic cylinder 21. The control of the operation of the hydraulic cylinder 21 can include a control of a speed of motion of the hydraulic cylinder 21. The control of the operation of the hydraulic cylinder 21 can include both the control of the direction of motion of the hydraulic cylinder 21 and the control of the speed of motion of the hydraulic cylinder 21. The direction of motion of the hydraulic cylinder 21 corresponds to a direction of motion of the piston 22. The speed of motion of the hydraulic cylinder 21 corresponds to a speed of motion of the piston 22.
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The flow control valve 23 is connected to a piston side of the hydraulic cylinder 21 by a first connection line 23a and to a piston rod side of the hydraulic cylinder 21 by a second connection line 23b. Generally, the number of the hydraulic cylinders and the number of the flow control valves in a hydraulic operation circuit of an underground mining vehicle may vary according to the intended use of the hydraulic operating circuit in the underground mining vehicle.
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The flow control valve 23 is configured to control the operation of the hydraulic cylinder 21 according to control actions received from a control unit 24. The control unit 24 is configured to control the operation of the flow control valve 23. By controlling the operation of the flow control valve 23 the control unit 24 can control the operation of the hydraulic operating circuit 20.
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The control unit 24 can control a flow rate of fluid flow through the flow control valve 23. The control unit 24 can control a flow direction of the fluid flow through the flow control valve 23. The control unit 24 can control both the flow rate of the fluid flow through the flow control valve 23 and the flow direction of the fluid flow through the flow control valve 23. By controlling the flow rate of the fluid flow through the flow control valve 23, the control unit 24 can control the speed of motion of the hydraulic cylinder 21. By controlling the flow direction of the fluid flow through the flow control valve 23, the control unit 24 can control the direction of motion of the hydraulic cylinder 21.
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Regarding to an underground mining vehicle, the underground mining vehicle comprises a load carrying element, a hydraulic operating circuit comprising at least one hydraulic cylinder for operating the load carrying element and a control system for controlling an operation of the hydraulic operating circuit, wherein the control system comprises at least one data acquisition device for collecting operational data representing an operation of the at least one of the hydraulic operating circuit and the at least one hydraulic cylinder, and a control unit configured to control the operation of the hydraulic operating circuit to control, based on the collected operational data, a speed of motion of the at least one hydraulic cylinder for providing a controllable cushioning effect for the at least one hydraulic cylinder.
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Regarding to a method for controlling an operation of an underground mining vehicle, wherein the underground mining vehicle comprises a hydraulic operating circuit comprising at least one hydraulic cylinder for operating a load carrying element of the underground mining vehicle, the method comprises collecting operational data representing an operation of the at least one of the hydraulic operating circuit and the at least one hydraulic cylinder, and controlling the operation of the hydraulic operating circuit to control, based on the collected operational data, a speed of motion of the at least one hydraulic cylinder for providing a controllable cushioning effect for the at least one hydraulic cylinder.
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The present application is thus based on the idea of monitoring at least one of the operation of the hydraulic operating circuit and the operation of the at least one hydraulic cylinder in the hydraulic operating circuit. The speed of motion of the at least one hydraulic cylinder is then controlled, based on that monitoring, for providing the controllable cushioning effect for the operation of the at least one hydraulic cylinder.
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The solution disclosed in the present application provides a controllable cushioning effect for the operation of the hydraulic cylinder to control the speed of motion of the hydraulic cylinder based on the monitoring of at least one of the operation of the hydraulic operating circuit and the operation of the at least one hydraulic cylinder in the hydraulic operating circuit. In other words, an effectiveness of the cushioning effect may be varied according to an operational state of at least one of the hydraulic operating circuit and the at least one hydraulic cylinder in the hydraulic operating circuit.
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The cushioning effect disclosed provides an increased component lifetime. The component lifetime refers herein to the lifetime of the hydraulic cylinders, as well as to the lifetime of the parts of the vehicle, which parts are operated by the hydraulic cylinders. The cushioning effect disclosed has also the effect of an increased user comfort by at least reducing intensity of shocks caused by the operation of the hydraulic cylinders.
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The loader 1 shown in Figure 1, and the dump truck 15 shown in Figure 3, are thus example embodiments of an underground mining vehicle, wherein the solution disclosed in the present application may be utilized. Another example embodiment of underground mining vehicle, wherein the solution disclosed in the present application may also be utilized, are for example rock drilling rigs comprising at least one boom provided with a rock drilling machine. In the rick drilling rigs, the solution disclosed may be applied to control for example an operation of a thrust cylinder of the rock drilling machine, or a cylinder operating a boom of the rock drilling rig. A further example of use case is a control of at least one cylinder of a hydraulic operated boom of a rock breaker, wherein the solution makes the operation smoother and extends the operating lifetime.
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An example embodiment of the method for controlling the operation of the underground mining vehicle is shown schematically in Figure 5. Some different example embodiments of the hydraulic operating circuit in the underground mining vehicle are shown schematically in Figures 6, 7 and 8. Referring to the example embodiments of Figures 6, 7 and 8, the hydraulic operating circuit 20 and the hydraulic cylinder 21 in the hydraulic operating circuit 20 may be configured to operate for example the middle joint 3, the bucket 4, the lift arm 5, or the dump box 16.
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According to an example embodiment, the at least one data acquisition device is a pressure sensing device arranged to measure a pressure in the hydraulic operating circuit, and the control unit is configured to retrieve from the pressure sensing device at least one pressure measurement value representing the pressure in the hydraulic operating circuit and to control the hydraulic operating circuit to limit the speed of motion of the at least one hydraulic cylinder based on the at least one pressure measurement value for providing a controllable cushioning effect for the hydraulic cylinder.
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According to this example embodiment, the hydraulic operating circuit comprises at least one pressure sensing device arranged to measure the pressure in the hydraulic operating circuit. The pressure may be measured for example in one or both of the connection lines, or in the hydraulic cylinder. The pressure may be measured at a specific moment of action of the hydraulic cylinder, i.e., at a specific moment during the stroke of the cylinder piston. In that case, the pressure sensing device provides a single pressure measurement value during the stroke of the cylinder piston. Alternatively, the pressure may be measured substantially continuously. In that case, the pressure sensing device provides a series of pressure measurement values during the stroke of the cylinder piston.
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The pressure measured in the hydraulic operating circuit is the operational data representing the operation of the hydraulic operating circuit. The measured pressure is also a measure that indicates mass of that part of the underground mining vehicle, which part is intended to be operated by the hydraulic cylinder. The greater the mass of the part of the underground mining vehicle, the higher the pressure required to operate the part of the underground mining vehicle. The pressure measured in the hydraulic operating circuit is thus information based on which the cushioning effect for the hydraulic cylinder can be controlled. This has the effect that when the mass of the part of the vehicle changes, the change in the mass of the part of the vehicle will automatically be taken into account in the control of the cushioning effect for the hydraulic cylinder through the pressure measured in the hydraulic operating circuit. This means for example that if the mass of the bucket of the loader changes due to a change of the bucket, the mass of the new bucket of the loader is automatically taken into account in the control of the cushioning for the tilt cylinder of the bucket, or in the control of the cushioning effect for the lift cylinder of the lift arm. An example embodiment of the hydraulic operating circuit 20 like that is shown schematically in Figure 6. The basic construction of the hydraulic operating circuit 20 in Figure 6 is like that shown in Figure 4. The hydraulic operating circuit 20 in Figure 6 further comprises a first pressure sensing device 25a arranged in the first connection line 23a of the hydraulic cylinder 21. The first pressure sensing device 25a is configured to measure one or more pressure measurement values Pa that represent the pressure in the first connection line 23a during the operation of the hydraulic cylinder 21.
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The hydraulic operating circuit 20 in Figure 6 further comprises a second pressure sensing device 25b arranged in the second connection line 23b of the hydraulic cylinder 21. The second pressure sensing device 25b is configured to measure one or more pressure measurement values Pb that represent the pressure in the second connection line 23b during the operation of the hydraulic cylinder 21.
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Depending on the direction of the stroke of the piston 22 of the hydraulic cylinder 21, either the one or more pressure measurement values Pa measured by the first pressure sensing device 25a, or the one or more pressure measurement values Pb measured by the second pressure sensing device 25b is/are received by the control unit 24. Alternatively, the one or more pressure measurement values Pa measured by the first pressure sensing device 25a, and the one or more pressure measurement values Pb measured by the second pressure sensing device 25b are received by the control unit 24. The control unit 24 is configured to control, based on the one or more pressure measurement values received by the control unit 24, the operation of the hydraulic operating circuit 20 to limit the speed of motion of the hydraulic cylinder 21 to implement the required cushioning effect for the hydraulic cylinder 21.
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The example embodiment of the hydraulic operating circuit 20 in Figure 6 comprises pressure sensing devices 25a, 25b in both connection lines 23a, 23b of the hydraulic cylinder 21. The hydraulic operating circuit 20 can thus implement the cushioning effect for the hydraulic cylinder 21 in a straightforward manner in both directions of action of the hydraulic cylinder 21. If the cushioning effect for the hydraulic cylinder 21 is deemed necessary only in one direction of action of the hydraulic cylinder 21, only one of the connection lines 23a, 23b of the hydraulic cylinder 21 may be provided with the pressure sensing device 25a, 25b.
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The measured pressures may also be gathered to provide information about the pressure to which the components of the underground mining vehicle are subjected to. Herein, for example, measured cylinder pressure peaks may be used to estimate stress to which the components of the underground mining vehicle are subjected to. This information may further be utilized to form information for predictive maintenance of the underground mining vehicle.
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According to an example embodiment, the at least one data acquisition device is a pressure sensing device arranged to measure a pressure in the hydraulic operating circuit, and the control unit is configured to retrieve from the pressure sensing device at least one measured pressure measurement value. The control unit is further configured to compare the retrieved at least one pressure measurement value to at least one reference value representing a similar operating state of the load carrying element to indicate a change in a characteristic feature of the load carrying element based on the comparison.
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According to this example embodiment, the hydraulic operating circuit comprises at least one pressure sensing device arranged to measure the pressure in the hydraulic operating circuit. The pressure may be measured, as disclosed above, at a specific moment of action of the hydraulic cylinder, i.e., at a specific moment during the stroke of the cylinder piston, or substantially continuously. The at least one measured pressure measurement value is compared to the at least one reference value representing a similar operating state of the load carrying element of the vehicle to indicate a change in a characteristic feature of the load carrying element of the vehicle based on the comparison. The characteristic feature of the load carrying element of the vehicle is a feature that relates to or describes a property of the load carrying element of the vehicle and is determinable based on the at least one measured pressure measurement value. The change in the characteristic feature of the load carrying element is thus identifiable based on the change in the measured pressure of the hydraulic operating circuit if the pressure has been measured during an operating state of the load carrying element, which operating state of the load carrying element is comparable to an operating state concerning on the reference value.
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The reference value may be a value set by a manufacturer of the underground mining vehicle. In that case the reference value may be based for example on a test drive carried out with the underground mining vehicle. Alternatively, the reference value may comprise at least one measured pressure measurement value representing the pressure in the hydraulic operating circuit during a similar operating state of the load carrying element of the underground mining vehicle.
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The operating state of the load carrying element, and the corresponding reference value, may take into account also an operating temperature of the underground mining vehicle, or a temperature of the hydraulic fluid. A viscosity of the hydraulic fluid changes with temperature. Changes in the viscosity of the hydraulic fluid affect the friction occurring during the operation of the load carrying element and thereby the pressure measured during the operation of the load carrying element.
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An example embodiment of the hydraulic operating circuit 20 like that is shown schematically in Figure 7. The basic construction of the hydraulic operating circuit 20 in Figure 7 is like that shown in Figure 6. The hydraulic operating circuit 20 in Figure 7 further comprises a database 26 comprising at least one data record. The at least one data record comprises at least one pressure measurement value representing the reference value. The at least one data record further comprises information indicating the operating state of the load carrying element of the underground mining vehicle concerning the reference value. The control unit 24 is configured to compare the presently measured at least one pressure measurement value to the at least one reference value representing a similar operating state of the load carrying element of the underground mining vehicle. Based on this comparison, the control unit 24 is configured to determine a change ΔCF in a characteristic feature of the part of the vehicle.
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According to an example embodiment, the characteristic feature of the load carrying element of the underground mining vehicle is a mass of the load carrying element. A change in the mass of the load carrying element of the underground mining vehicle can thus be recognized based on the change in the measured pressure.
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The mass of the load carrying element of the underground mining vehicle may indicate for example a mass of the bucket of the loader. In the dump trucks, the mass of the load carrying element may indicate a mass of the dumb box of the dump truck. Based on the measured pressure, the change in the mass of the load carrying element of the underground mining vehicle in question is automatically taken into account for providing an appropriate cushioning effect in the operation of the hydraulic cylinder(s). This has the effect that a working comfort of the operator is automatically adjustable. In other words, the working comfort is the same regardless of the mass of the load carrying element also in cases wherein an original load carrying element has been replaced with a different one, even if the mass gets heavier and increases the overall mass of the load carrying element.
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The change in the mass of the bucket of the loader may result for example from a change of the bucket, from a change of the wear part of the bucket, from a breakage of the bucket, such as, for example, a wear part coming off the bucket, or from the load sticking to the bucket. The change in the mass of the dump box of the dump truck may result for example from a change of the dump box, from a breakage of the dump box, or from the load sticking to the dump box. The change in the mass of the load carrying element may thus take place abruptly because of the breakage of the part. Alternatively, the change in the mass of the load carrying element may take place trend-like because of more and more load sticking to the bucket or dump box over time, or due to wear of a lip plate or wear parts in the bucket of the loader. The measured pressures can thereby be used for example to follow the trend how the lip plate and wear parts are worn.
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According to an example embodiment, the at least one data acquisition device is a position detection device for collecting data representing information about a position of at least one of a moving cylinder piston and a moving load carrying element as a response to the hydraulic cylinder operating the load carrying element of the underground mining vehicle, and the control unit is configured to determine the speed of motion of the hydraulic cylinder based on the data representing successive positions of the at least one of the moving cylinder piston and the moving load carrying element, and to control the hydraulic operating circuit to limit the speed of motion of the hydraulic cylinder based on the determined speed of motion of the hydraulic cylinder for providing the controllable cushioning effect for the hydraulic cylinder.
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According to this example embodiment, data representing information about the position of the moving cylinder piston is collected as a response to the hydraulic cylinder operating the load carrying element of the vehicle. The data is collected substantially continuously. The speed of motion of the hydraulic cylinder is determined based on the data representing successive positions of at least one of the moving cylinder piston and the moving load carrying element. The hydraulic operating circuit is controlled to limit the speed of motion of the hydraulic cylinder based on the determined speed of motion of the hydraulic cylinder for providing the controllable cushioning effect for the hydraulic cylinder.
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An example embodiment of the hydraulic operating circuit 20 like that is shown schematically in Figure 8. The basic construction of the hydraulic operating circuit 20 in Figure 8 is like that shown in Figure 4. The hydraulic operating circuit 20 in Figure 8 further comprises a position detection device 27 configured to collect data representing information about the position of at least one of the moving cylinder piston 22 and the moving load carrying element as a response to the hydraulic cylinder 21 operating the load carrying element of the underground mining loader. The control unit 24 is configured to determine the speed of motion of the hydraulic cylinder 21 based on the data representing successive positions of at least one of the moving cylinder piston 22 and the moving load carrying element. The control unit 24 is further configured to control the hydraulic operating circuit 20 to limit the speed of motion of the hydraulic cylinder 21 based on the determined speed of motion of the hydraulic cylinder 21 to implement the required cushioning effect for the hydraulic cylinder 21.
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According to this example embodiment, the end cushioning of the hydraulic cylinder 21 is controlled based on the speed of motion of the hydraulic cylinder 21. This control implementation takes into account changes in the mass of the load carrying element of the underground mining vehicle. This control implementation takes into account also a change in a viscosity of the hydraulic fluid. The viscosity of the hydraulic fluid can change for example because of changes in temperature of the operating environment of the underground mining vehicle.
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According to an example embodiment, the position detection device 27 is a linear position sensor arranged to measure at least one of the position of the cylinder piston 22 and the position of the load carrying element of the vehicle. In that case, the control unit 24 is configured to determine the speed of motion of the hydraulic cylinder 21 based on the data representing successive linear position measurements. The linear position sensor may be for example any kind of distance sensor, such as a resistance based linear measurement sensor, magneto strictive sensor, ultrasound sensor, laser sensor, pulse sensor, or any combination of the previous examples.
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According to an example embodiment, the position detection device 27 is an angular position sensor arranged to measure an angular position of the load carrying element of the vehicle. In that case the control unit 24 is configured to determine the speed of motion of the hydraulic cylinder 21 based on the data representing successive angular position measurements. The angular position sensor may be for example an angle sensor, such as an absolute angle sensor. The angular position sensor like that is arranged at a joint of the load carrying element, about which joint the load carrying element turns.
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According to an example embodiment, the position detection device 27 is a vision sensor arranged to visually monitor the position of at least one of the cylinder piston 22 and the load carrying element of the underground mining vehicle. The vision sensor may be for example a scanner or a camera.
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In the examples above, the speed of motion of the hydraulic cylinder was determined based on the data representing successive positions of the at least one of the moving cylinder piston and the moving load carrying element collected by at least one position detection device. Alternatively, the speed of motion of the hydraulic cylinder was determined based on acceleration data from one or more acceleration sensor arranged to measure an acceleration of a movement of the at least one of the moving cylinder piston and the moving load carrying element.
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According to an example embodiment, the control unit is configured to control the hydraulic operating circuit to decrease a flow rate of the hydraulic fluid outflow from the hydraulic cylinder to limit the speed of motion of the hydraulic cylinder for providing the controllable cushioning effect for the hydraulic cylinder. The hydraulic operating circuit is thus controlled to decrease the flow rate of the hydraulic fluid outflow from the hydraulic cylinder to limit the speed of motion of the hydraulic cylinder for providing the controllable cushioning effect for the hydraulic cylinder. Referring to the example embodiments of Figures 6, 7 and 8, the control unit 24 is configured to control the flow control valve 23 to limit the flow rate of the hydraulic fluid out of the hydraulic cylinder 21 based on the collected operational data. The operational data represents the operation of the at least one of the hydraulic operating circuit 20 and the at least one hydraulic cylinder 21.
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According to this example embodiment, the cushioning effect for the hydraulic cylinder is implemented by controlling the flow rate of the fluid out of the hydraulic cylinder.
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According to an example embodiment, the control unit is configured to control the hydraulic operating circuit to limit the speed of motion of the hydraulic cylinder by controlling at least one of a starting time of the limitation of the speed of motion of the hydraulic cylinder and a degree of the limitation of the speed of motion of the hydraulic cylinder. The hydraulic operating circuit can thus be controlled to limit the speed of motion of the hydraulic cylinder by controlling the starting time of the limitation of the speed of motion of the hydraulic cylinder. Alternative, the hydraulic operating circuit can be controlled to limit the speed of motion of the hydraulic cylinder by controlling the degree of the limitation of the speed of motion of the hydraulic cylinder. The hydraulic operating circuit can also be controlled to limit the speed of motion of the hydraulic cylinder by controlling both the starting time of the limitation of the speed of motion of the hydraulic cylinder and the degree of the limitation of the speed of motion of the hydraulic cylinder.
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According to the example embodiment of the preceding paragraph, referring to the example embodiments of Figures 6, 7 and 8, the control unit 24 is configured to control the instant of time at which the control unit 24 starts to control the flow control valve 23 to limit the flow rate of the hydraulic fluid out of the hydraulic cylinder 21 based on the collected operational data, wherein the operational data represents the operation of the at least one of the hydraulic operating circuit 20 and the at least one hydraulic cylinder 21. Additionally, or alternatively, the control unit 24 is configured to control the degree, i.e., the amount, at which the flow control valve 23 limits the flow rate of the fluid out of the hydraulic cylinder 21. The degree at which the flow control valve 23 limits the flow rate of the hydraulic fluid out of the hydraulic cylinder 21 can be controlled by adjusting an opening of the flow control valve 23.
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According to an example, when the piston 22 of the hydraulic cylinder 21 approaches a specific stopping point, for example an end of movement and the mass of the load carrying element of the underground mining vehicle to be moved by the operation of the hydraulic cylinder is high and the speed of motion of the hydraulic cylinder is high, the control unit 24 can start to control the flow control valve 23 to limit the flow rate of the hydraulic fluid out of the hydraulic cylinder 21 sooner than conventionally. Alternatively, or additionally, the control unit 24 can start to control the flow control valve 23 to limit the flow rate of the hydraulic fluid out of the hydraulic cylinder 21 with a higher degree than conventionally. On the other hand, if the mass of the load carrying element of the underground mining vehicle to be moved by the operation of the hydraulic cylinder is small and the speed of motion of the hydraulic cylinder is low, the control unit 24 can start to control the flow control valve 23 to limit the flow rate of the hydraulic fluid out of the hydraulic cylinder 21 later than conventionally. Alternatively, or additionally, in that case the control unit 24 can start to control the flow control valve 23 to limit the flow rate of the hydraulic fluid out of the hydraulic cylinder 21 with a lower degree than conventionally. Other combinations of the control of the starting time of the limitation of the speed of motion of the hydraulic cylinder and the degree of the limitation of the speed of motion of the hydraulic cylinder are also selectable based on the collected operational data representing the operation of the at least one of the hydraulic operating circuit and the at least one hydraulic cylinder in the hydraulic operating circuit.
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In the example above, the flow rate of the hydraulic fluid out of the hydraulic cylinder was limited for providing the desired cushioning effect for the operation of the hydraulic cylinder. According to an example embodiment, instead of limiting the flow rate of the hydraulic fluid out of the hydraulic cylinder, the flow rate of the hydraulic fluid into the hydraulic cylinder may be limited for providing the desired cushioning effect for the operation of the hydraulic cylinder. According to another example embodiment, in addition to limiting the flow rate of the hydraulic fluid out of the hydraulic cylinder, also the flow rate of the hydraulic fluid into the hydraulic cylinder may be limited for providing the desired cushioning effect for the operation of the hydraulic cylinder.
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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 present application and its example embodiments are not limited to the examples described above but may vary within the scope of the claims.