Hydraulic systems, mining vehicles, and methods

Abstract

A hydraulic system, a mining vehicle, and a method for flushing a closed-loop hydraulic circuit. The hydraulic system (HS) provides at least one closed hydraulic circuit (CL) with a hydraulic pump, a motor, and one or more hydraulic actuators. The hydraulic system further includes a flushing system for draining and supplying a limited amount of hydraulic fluid for flushing the closed-loop hydraulic circuit. There is a drain valve (DV) actively controlled by a control unit (CU), which selectively controls fluid flow through the valve.

Description

[Background technology]

[0001] The present invention relates to a hydraulic system for a mining vehicle, the hydraulic system being provided with a closed-loop hydraulic circuit, the closed-loop hydraulic circuit being flushed by a flushing system.

[0002] The invention further relates to a mining vehicle and a method for flushing a closed-loop hydraulic circuit of a hydraulic system by means of a flushing system.

[0003] The field of the invention is more particularly defined in the preambles of the independent claims.

[0004] In mines and other work sites, different types of mining vehicles are used. The mining vehicles are provided with several hydraulic actuators connected to a hydraulic system. Furthermore, the hydraulic system may comprise one or more closed-loop hydraulic systems, in which pressurized hydraulic fluid is circulated from the outlet port of the hydraulic pump to the inlet port of the hydraulic actuators and from the outlet port of the hydraulic actuators to the inlet port of the first hydraulic pump. However, it may be necessary to flush the closed-loop hydraulic system by feeding fresh hydraulic fluid into the closed-loop hydraulic system. In some known solutions, flushing the closed hydraulic system is performed by a flushing fluid flow caused by a flushing pump connected in parallel to the main hydraulic pump so as to be driven simultaneously. The caused flushing flow and pressure are then controlled by separate control valves. It has been shown that the known solutions for flushing have several drawbacks, in particular related to poor energy efficiency and unsatisfactory controllability of the flushing. Summary of the Invention

[0005] It is an object of the present invention to provide a new and improved hydraulic system, a mining vehicle equipped with such a closed hydraulic system, and a method for flushing a closed loop hydraulic circuit.

[0006] The hydraulic system according to the invention is characterized by the features of the first independent device claim.

[0007] A mining vehicle according to the invention is characterised by the features of the second independent device claim.

[0008] The method according to the invention is characterized by the features of the independent method claim.

[0009] The idea of ​​the disclosed solution is to provide a flushing system in the closed-loop hydraulic circuit of a hydraulic system, comprising at least one supply mechanism for supplying a limited amount of additional hydraulic fluid from a separate hydraulic fluid source to the closed-loop hydraulic circuit, and a drain mechanism for draining a limited amount of used hydraulic fluid from the closed-loop hydraulic circuit to a separate hydraulic fluid source, whereby the flushing system provides a limited flushing flow to the closed-loop hydraulic circuit by controlling the supply and drain. In the disclosed solution, said drain mechanism comprises at least one drain valve that is actively controlled under the control of the at least one control unit, the fluid flow through the drain valve being selectively controllable.

[0010] In other words, the closed loop hydraulic circuit is provided with an actively controlled bypass flow system that allows limited flow of pressure fluid to be supplied to and removed from the closed loop hydraulic circuit to ensure proper quality of hydraulic fluid within the system.

[0011] The advantage of the disclosed solution is that the flushing can be effectively and accurately controlled when the control unit actively controls the bypass flow system. The control unit can also monitor several parameters and take them into account in the control of the flushing. When active control is performed by the control unit, more versatile flushing control principles and environments can be realized. Furthermore, the improved control also makes the system more effective and saves energy.

[0012] In a closed loop hydraulic circuit, pressurized hydraulic fluid flows directly from a hydraulic pump to a hydraulic actuator, typically a hydraulic motor, and back to the hydraulic pump without going into a tank or other hydraulic fluid reservoir. The flow and direction of the hydraulic fluid controls the hydraulic motor. The hydraulic motor can operate in either direction. In a closed loop system, hydraulic pressure and flow are produced only when and as much as is needed.

[0013] According to one embodiment, the supply mechanism may comprise one or more supply valves for controlling the supply of fresh hydraulic fluid to the closed-loop hydraulic circuit.

[0014] According to one embodiment, both the supply mechanism and the exhaust mechanism are in direct fluid communication with a tank that serves as a separate source of hydraulic fluid.

[0015] According to one embodiment, the hydraulic system comprises at least one filtering or cooling device for treating the discharged hydraulic fluid before supplying it to the closed-loop hydraulic circuit through the supply mechanism. The filtering or cooling device may be arranged in connection with the fluid source or reservoir.

[0016] According to one embodiment, the supply mechanism comprises a second hydraulic pump driven by at least one dedicated second motor. In other words, the disclosed flushing mechanism comprises a separate hydraulic pump for generating the required flushing flow. The pump is actuated by a dedicated motor, whereby the operation of the pump is controllable independently of the pumping means of the closed-loop hydraulic circuit.

[0017] According to one embodiment, the hydraulic system comprises an open hydraulic circuit acting as a common rail hydraulic circuit, the open hydraulic circuit being configured to provide hydraulic fluid to the flushing system and to at least one hydraulic actuator coupled to the open hydraulic circuit. The open hydraulic circuit is provided with a second hydraulic pump driven by at least one dedicated second motor under the control of the control unit. In this embodiment, the second hydraulic pump can be utilized not only for flushing purposes but also for driving selected hydraulic auxiliary devices of the mining vehicle. And, a separate hydraulic pump is not required just for flushing.

[0018] According to one embodiment, the at least second motor is a speed-controlled electric motor controlled by at least one electric motor control device and the at least second hydraulic pump is a fixed displacement pump, and the control unit is configured to control said electric motor control device to regulate the pressure and flow magnitude of the hydraulic fluid affecting in the supply mechanism of the flushing system.

[0019] According to one embodiment, the second hydraulic pump for generating the flushing flow may alternatively be any kind of hydraulic pump. Thus, the second hydraulic pump may be, for example, a variable displacement pump.

[0020] According to one embodiment, the closed loop hydraulic circuit is provided with one or more sensing devices for sensing properties of the hydraulic fluid, and a control unit is provided with the sensing data and generates a control signal for controlling at least the exhaust valve in response to the sensing data.

[0021] According to one embodiment, the sensory data described in the previous embodiment is also used to control the operation of the second motor and the magnitude of the induced flushing flow.

[0022] According to one embodiment, said sensing device is a temperature sensor for sensing the temperature of the hydraulic fluid.The control unit may control the flushing to cool the temperature of the circuit.

[0023] According to one embodiment, the sensing device is a fluid condition monitoring sensor for sensing a fluid property of a hydraulic fluid.

[0024] According to one embodiment, the fluid condition monitoring sensor is a sensor or analytical device for detecting the cleanliness of the hydraulic fluid.

[0025] According to one embodiment, the closed loop hydraulic circuit is further provided with one or more pressure or flow sensors. The generated sensory data is transmitted to the control unit. Additionally, a temperature of the pressurized fluid may be sensed in connection with the at least one hydraulic actuator. The control unit may be configured to provide a control signal in response to the received sensory data.

[0026] According to one embodiment, the control unit detects operating conditions of the closed-loop hydraulic circuit and generates a control signal for controlling at least a drain valve of the flushing system in response to the detected operating conditions.

[0027] According to one embodiment, the control unit is configured to detect a duty cycle of the closed loop hydraulic circuit and to increase flushing when the detected duty cycle exceeds a predetermined limit.

[0028] According to one embodiment, the control unit is configured to detect an operating time or duration of the closed loop hydraulic circuit and to increase flushing when the detected operating time exceeds a predetermined limit.

[0029] According to one embodiment, the control unit is configured to monitor operation of the closed loop hydraulic circuit and is configured to increase flushing when the cumulative magnitude of the load or the estimated magnitude of the load for a next operation exceeds a predetermined limit value set for the load.

[0030] According to one embodiment, the control unit is configured to operate the flushing system to continue cooling the pressure fluid in the closed-loop hydraulic circuit even when the operation of the closed-loop hydraulic circuit is switched off, thus realizing a kind of final cooling for independently cooling the hydraulic fluid for a desired period of time, so that the hydraulic system is ready for the next operation.

[0031] According to one embodiment, the control unit is configured to detect operating conditions that the closed loop hydraulic circuit is operating in. The control unit may, for example, increase flashing when operating in harsh conditions and at high temperatures.

[0032] According to one embodiment, the control unit may be provided with a user interface through which an operator of the mining vehicle can communicate with the control unit, enter control parameters and make selections. The control unit may provide the operator with usable information by means of the user interface.

[0033] According to one embodiment, the disclosed solution relates to a mining vehicle comprising a movable carrier and one or more mining operation devices mounted on the carrier, the mining vehicle further comprising at least one hydraulic system according to the embodiments and features disclosed herein.

[0034] According to one embodiment, the mining vehicle is a rock drilling rig, a rock bolting device, a shotcrete device, a mining load vehicle, or a mine truck. The disclosed closed loop hydraulic circuit may be arranged to operate, for example, a track haulage or drive actuator, or a mining actuator.

[0035] According to one embodiment, the disclosed solution relates to a method for flushing a closed-loop hydraulic circuit of a hydraulic system by a flushing system, the method comprising: supplying additional hydraulic fluid to the closed-loop hydraulic circuit; and draining hydraulic fluid from the closed-loop hydraulic circuit. The method further comprises controlling at least a magnitude of the draining of hydraulic fluid by a control unit.

[0036] The above disclosed embodiments may be combined to form a suitable solution having the required features described above.

[0037] Some embodiments are explained in more detail in the accompanying drawings. [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 is a schematic diagram of a hydraulic circuit diagram of a disclosed hydraulic system including a closed-loop hydraulic circuit and a flushing system for flushing the closed-loop hydraulic circuit. [Diagram 2] FIG. 2 is a schematic diagram illustrating some control principles of the disclosed solution. [Diagram 3] FIG. 2 is a schematic diagram of an alternative hydraulic circuit diagram of the disclosed hydraulic system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] For clarity, the figures show in a simplified manner some embodiments of the disclosed solutions, in which like reference numbers identify like elements.

[0040] FIG. 1 shows a hydraulic circuit diagram of a hydraulic system HS of a mining vehicle, such as a rock drilling rig. The hydraulic system HS is provided with a closed-loop hydraulic circuit CL comprising a first hydraulic pump Hp1 driven by a first motor M1. A hydraulic actuator HA is connected to the closed-loop hydraulic circuit CL. As shown in FIG. 1, pressurized hydraulic fluid is directed in the closed-loop hydraulic circuit CL to circulate from the outlet port of the first hydraulic pump Hp1 to the inlet port of the hydraulic actuator HA and from the outlet port of the hydraulic actuator HA to the inlet port of the first hydraulic pump Hp1. In FIG. 1, the inlet and outlet ports are not marked for clarity, since the first hydraulic pump Hp1 and the hydraulic actuator Hp can be rotated in both rotational directions.

[0041] The hydraulic system HS comprises a flushing system FLS provided with a supply mechanism FA for supplying a limited amount of additional hydraulic fluid from a separate hydraulic fluid source T to the closed-loop hydraulic circuit CL and also provided with a drain mechanism DA for draining a limited amount of used hydraulic fluid from the closed-loop hydraulic circuit CL to the separate hydraulic fluid source T. The separate hydraulic fluid source T may be, for example, a tank or a reservoir.

[0042] The discharge mechanism DA further comprises a discharge valve DV that is actively controlled under the control of the control unit CU. Fluid flow through the discharge valve DV can be selectively controlled under the control of the control unit CU. The control unit CU may comprise a processor configured to generate control signals in response to sensory data being received from one or more sensing devices S. The control unit CU may be provided with a user interface UI for communicating with an operator. Control parameters and computer program products may be input to the control unit CU.

[0043] The supply mechanism FA comprises a second hydraulic pump Hp2 driven by a dedicated second motor M2. The supply mechanism further comprises a supply valve for controlling the supply of fresh hydraulic fluid to the closed-loop hydraulic circuit CL.

[0044] Both the supply mechanism FA and the exhaust mechanism DA are in direct fluid communication with a tank which serves as a separate source T of hydraulic fluid.

[0045] There may be one or more filtering or cooling devices CD to treat the discharged hydraulic fluid before supplying it to the closed loop hydraulic circuit CL through a supply mechanism FA. The filtering or cooling device CD may be arranged in connection with the fluid source T.

[0046] FIG. 2 discloses some control principles 1 for controlling the flushing of a closed-loop hydraulic circuit. The control 1 may be based on fluid control monitoring 2 or on action items 3 or both. The fluid condition monitoring 2 may comprise sensory data 4 on the properties of the hydraulic fluid. And there are one or more fluid condition monitoring sensors for sensing the fluid properties of the hydraulic fluid. A temperature sensor may be provided for sensing the temperature 5 of the hydraulic fluid. The control unit may control the flushing to cool the temperature of the circuit. Alternatively or additionally, there may be one or more fluid condition monitoring sensors or analysis devices for detecting the cleanliness 6 of the hydraulic fluid.

[0047] The above mentioned operational matters 3 may relate to detection 7 of the operating conditions of the closed loop hydraulic circuit. The control may take into account the usage duty 8, the operating time 9, the load magnitude of the operation 10 and may also arrange for pre-flushing 11 before the next load environment.

[0048] Additionally, the control unit may detect operating conditions 12 in which the closed loop hydraulic circuit is operating, and the control unit may increase flashing, for example, when operating in harsh conditions and at high temperatures.

[0049] Figure 3 discloses a hydraulic system HS which differs from that shown in Figure 1 only in that the second pump Hp2 is configured to also generate hydraulic power for an open-loop hydraulic circuit Op provided with one or more hydraulic auxiliary actuators Aa. There may be a valve V for controlling the supply of hydraulic fluid in the open-loop hydraulic circuit Op to the auxiliary actuators Aa. The open-loop hydraulic circuit with the auxiliary actuators Aa may be referred to as a common rail circuit.

[0050] The drawings and the associated description are intended only to illustrate the ideas of the invention, the details of which may vary within the scope of the claims.

Claims

1. 1. A mining vehicle, comprising: A movable carrier; at least one mining operation device mounted on the movable carrier; At least one hydraulic system (HS), The hydraulic system (HS) includes: at least one first hydraulic pump (Hp1) driven by at least one first motor (M1); At least one closed loop hydraulic circuit (CL) is provided, comprising at least one hydraulic actuator (HA), at least one hydraulic system (HS) in which pressurized hydraulic fluid is directed to circulate in the closed loop hydraulic circuit (CL) from an outlet port of the first hydraulic pump (Hp1) to an inlet port of the hydraulic actuator (HA) and from an outlet port of the hydraulic actuator (HA) to an inlet port of the first hydraulic pump (Hp1); A flushing system (FLS) comprising at least one supply mechanism (FA) for supplying a limited amount of additional hydraulic fluid from a separate hydraulic fluid source (T) to said closed loop hydraulic circuit (CL) and a drain mechanism (DA) for draining a limited amount of used hydraulic fluid from said closed loop hydraulic circuit (CL) to said separate hydraulic fluid source (T), a flushing system (FLS), wherein the exhaust mechanism (DA) comprises at least one exhaust valve (DV) actively controlled under the control of at least one control unit (CU), the fluid flow through the exhaust valve (DV) being selectively controllable; A mining vehicle comprising: the hydraulic system (HS) comprises an open hydraulic circuit (Op) acting as a common rail hydraulic circuit, the open hydraulic circuit (Op) being configured to provide hydraulic fluid to the flushing system and to at least one hydraulic actuator (Aa) coupled to the open hydraulic circuit (Op); 13. A mining vehicle, characterized in that said open hydraulic circuit (Op) is provided with a second hydraulic pump (Hp2) driven by at least one dedicated second motor (M2) under the control of said control unit (CU).

2. said closed loop hydraulic circuit (CL) is provided with at least one sensing device (S) for sensing a property of a hydraulic fluid in said closed loop hydraulic circuit (CL); the control unit (CU) is configured to receive sensory data from the sensing device (S) and to generate a control signal for controlling at least the drain valve (DV) of the flushing system (FLS) in response to the received sensory data.

2. The mining vehicle of claim 1.

3. characterised in that the sensing device (S) is a temperature sensor for sensing the temperature of the hydraulic fluid, 3. The mining vehicle of claim 2.

4. The sensing device (S) is a fluid condition monitoring sensor for sensing a fluid property of the hydraulic fluid.

3. The mining vehicle of claim 2.

5. The control unit (CU) is configured to detect an operating condition of the closed loop hydraulic circuit (CL) and to generate a control signal for controlling at least the discharge valve (DV) of the flushing system (FLS) in response to the detected operating condition. A mining vehicle according to any one of claims 1 to 4.

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