A mining vehicle

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-loop hydraulic circuit (CL) including a hydraulic pump, a motor, and one or more hydraulic actuators. The hydraulic system also includes a flushing system for discharging and feeding a limited amount of hydraulic fluid to flush the closed-loop hydraulic circuit. A drain valve (DV) is present, which is actively controlled by means of a control unit (CU) to selectively control the fluid flow through the valve.

Description

Technical Field

[0001] The invention relates to a hydraulic system of a mining vehicle. The hydraulic system is provided with a closed-loop hydraulic circuit. The closed-loop hydraulic circuit is flushed by means of 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. Background Art

[0003] In mines and at other worksites, different types of mining vehicles are used. These 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 a pressurized hydraulic fluid circulates from an outlet port of a hydraulic pump to an inlet port of a hydraulic actuator and further from the outlet port of the hydraulic actuator to an inlet port of a first hydraulic pump. However, there may be a need to flush the closed-loop hydraulic system by feeding fresh hydraulic fluid in the closed-loop hydraulic system. In some known solutions, flushing of the closed hydraulic system is performed by means of a flushing fluid flow, wherein the flushing fluid flow is generated by means of a flushing pump, which is connected in parallel with a main hydraulic pump and driven simultaneously. The flushing flow and pressure generated are then controlled by a separate control valve. Known solutions for flushing have been shown to have some disadvantages, which relate in particular to low energy efficiency and unsatisfactory controllability of the flushing. Summary of the invention

[0004] The object of the present invention is to provide a novel and improved hydraulic system, a mining vehicle equipped with such a closed hydraulic system and a method for flushing a closed-loop hydraulic circuit.

[0005] The idea of ​​the disclosed solution is that a closed-loop hydraulic circuit of a hydraulic system is provided with a flushing system comprising at least one feeding device for feeding a limited amount of additional hydraulic fluid from a separate hydraulic fluid source to the closed-loop hydraulic circuit and a drain device for draining a limited amount of used hydraulic fluid from the closed-loop hydraulic circuit to the separate hydraulic fluid source. Thereby, the flushing system provides a limited flushing flow for the closed-loop hydraulic circuit by controlling the feeding and draining. In the disclosed solution, the drain device comprises at least one drain valve actively controlled under the control of at least one control unit and wherein the fluid flow through the drain valve is selectively controllable.

[0006] In other words, the closed-loop hydraulic circuit is provided with an actively controlled bypass flow system that allows a limited flow of pressurized fluid to be fed into and out of the closed-loop hydraulic circuit to ensure proper quality of the hydraulic fluid in the system.

[0007] The advantage of the disclosed solution is that when the control unit actively controls the bypass flow system, flushing can be effectively and accurately controlled. The control unit can also monitor several parameters and take these into account in the control of the flushing. When active control is performed by means of the control unit, more general flushing control principles and situations can be implemented. Furthermore, the improved control makes the system more efficient and saves energy.

[0008] 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 directly to the hydraulic pump without entering 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 generated only when needed, and only as much as is needed.

[0009] According to one embodiment, the feed arrangement may comprise one or more feed valves for controlling the feed of fresh hydraulic fluid to the closed-loop hydraulic circuit.

[0010] According to one embodiment, both the feed device and the discharge device are in direct fluid connection with a tank serving as said sole source of hydraulic fluid.

[0011] According to one embodiment, the hydraulic system comprises at least one filtering or cooling device for treating the exhausted hydraulic fluid before feeding it to the closed-loop hydraulic circuit via the feeding device.The filtering or cooling device may be arranged in connection with a fluid source or a fluid reservoir.

[0012] According to one embodiment, the feeding device comprises a second hydraulic pump driven by means of at least one dedicated second motor. In other words, the disclosed flushing device comprises a separate hydraulic pump for generating the required flushing flow. The pump is actuated by means of a dedicated motor, whereby the operation of the pump can be controlled independently of the pumping device of the closed-loop hydraulic circuit.

[0013] According to one embodiment, the hydraulic system comprises an open-loop hydraulic circuit, which serves as a common rail hydraulic circuit and is configured to provide hydraulic fluid to a flushing system and at least one hydraulic actuator coupled to the open-loop hydraulic circuit. The open-loop hydraulic circuit is provided with a second hydraulic pump, which is driven by means of at least one dedicated second motor under the control of a 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. Thus, a separate hydraulic pump only for flushing is not required.

[0014] According to one embodiment, at least the second motor is a speed-controlled electric motor controlled by means of at least one electric motor control device, and at least the second hydraulic pump is a fixed displacement pump. The control unit is then configured to control the electric motor control device for adjusting the magnitude of the pressure and flow of the hydraulic fluid affecting the feed device of the flushing system.

[0015] According to one embodiment, alternatively, the second hydraulic pump for generating the flushing flow may be any type of hydraulic pump. Thus, the second hydraulic pump may be, for example, a variable displacement pump.

[0016] According to one embodiment, the closed-loop hydraulic circuit is provided with one or more sensing devices for sensing properties of the hydraulic fluid.The control unit is provided with the sensed data and generates a control signal for controlling at least the discharge valve in response to the sensed data.

[0017] According to one embodiment, the sensing data mentioned in the previous embodiments are also used to control the operation of the second motor and the size of the flushing flow generated.

[0018] According to one embodiment, the sensing means is a temperature sensor for sensing the temperature of the hydraulic fluid.The control unit may control flushing for cooling the temperature of the circuit.

[0019] According to one embodiment, the sensing device is a fluid condition monitoring sensor for sensing a fluid property of a hydraulic fluid.

[0020] According to one embodiment, the fluid condition monitoring sensor is a sensor or an analysis device for detecting the cleanliness of the hydraulic fluid.

[0021] According to one embodiment, the closed-loop hydraulic circuit is further provided with one or more pressure or flow sensors. The generated sensing data is transmitted to the control unit. In addition, the temperature of the pressure fluid can be sensed in conjunction with at least one hydraulic actuator. The control unit can be configured to provide a control signal in response to the received sensing data.

[0022] According to one embodiment, the control unit detects an operating state of the closed-loop hydraulic circuit and generates a control signal in response to the detected operating state for controlling at least a discharge valve of the flushing system.

[0023] According to one embodiment, the control unit is configured to detect a usage rate of the closed-loop hydraulic circuit and to increase flushing when the detected usage rate exceeds a predetermined limit value.

[0024] According to one embodiment, the control unit is configured to detect an operation time or period of the closed-loop hydraulic circuit and to increase flushing when the detected operation time exceeds a predetermined limit value.

[0025] According to one embodiment, the control unit is configured to monitor the operation of the closed-loop hydraulic circuit and to increase flushing when the accumulated size of the load or the estimated size of the load of an upcoming operation exceeds a predetermined limit value set for said load.

[0026] According to one embodiment, the control unit is configured to operate the flushing system in order to continue cooling the pressure fluid in the closed-loop hydraulic circuit even when the operation of the closed-loop hydraulic circuit is shut down. In this way, a kind of aftercooling can be implemented to cool the hydraulic fluid independently and for a desired period of time. In this way, the hydraulic system can be prepared for the upcoming operation.

[0027] According to one embodiment, the control unit is configured to detect operating conditions of the closed-loop hydraulic circuit operation. For example, when operating in harsh conditions and high temperatures, the control unit can increase flushing.

[0028] According to one embodiment, the control unit may be provided with a user interface by means of which an operator of the mining vehicle can communicate with the control unit, can input control parameters, and can make selections. The control unit may provide available information to the operator by means of the user interface.

[0029] According to one embodiment, the disclosed solution relates to a mining vehicle. The mining vehicle comprises a movable carrier and one or more mining operation devices mounted on the carrier. The mining vehicle also comprises at least one hydraulic system according to the embodiments and features disclosed in this document.

[0030] According to one embodiment, the mining vehicle is a rock drill, a rock bolting device, a shotcrete device, a mining loading vehicle or a mining truck.For example, the disclosed closed-loop hydraulic circuit may be arranged to operate a travel or drive actuator or a mining actuator.

[0031] According to one embodiment, the disclosed solution relates to a method for flushing a closed-loop hydraulic circuit of a hydraulic system by means of a flushing system. The method comprises: feeding 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 the amount of draining of the hydraulic fluid by means of a control unit.

[0032] The embodiments disclosed above may be combined in order to form a suitable solution having desired ones of the above features. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Some embodiments are described in more detail in the accompanying drawings, in which

[0034] Figure 1is a schematic diagram of a hydraulic diagram of a disclosed hydraulic system, the hydraulic system comprising a closed-loop hydraulic circuit and a flushing system for flushing the closed-loop hydraulic circuit,

[0035] Figure 2 is a schematic diagram illustrating some control principles of the disclosed solution, and

[0036] Figure 3 is a schematic diagram of an alternative hydraulic diagram for the disclosed hydraulic system.

[0037] For the sake of clarity, the drawings show some embodiments of the disclosed solution in a simplified manner. In the drawings, the same reference numerals identify the same elements. DETAILED DESCRIPTION

[0038] Figure 1 A hydraulic diagram of a hydraulic system HS of a mining vehicle such as a rock drill is shown. The hydraulic system HS is provided with a closed-loop hydraulic circuit CL comprising a first hydraulic pump Hp1 driven by means of a first motor M1. A hydraulic actuator HA is connected to the closed-loop hydraulic circuit CL. Figure 1 As shown in , the pressurized hydraulic fluid is directed to circulate from the outlet port of the first hydraulic pump Hp1 to the inlet port of the hydraulic actuator HA in the closed-loop hydraulic circuit CL, and further circulates from the outlet port of the hydraulic actuator HA to the inlet port of the first hydraulic pump Hp1. Figure 1 In FIG. 1 , the first hydraulic pump Hp1 and the hydraulic actuator Hp can be rotated in both rotational directions, therefore, the inlet ports and the outlet ports are not marked for reasons of clarity.

[0039] The hydraulic system HS comprises a flushing system FLS provided with feeding means FA for feeding 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 draining means DA for draining a limited amount of used hydraulic fluid from the closed-loop hydraulic circuit CL to said separate hydraulic fluid source T. The separate hydraulic fluid source T may be a tank or a reservoir, for example.

[0040] The discharge arrangement DA further comprises a discharge valve DV which is actively controlled under the control of the control unit CU. The 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 sensing data 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.

[0041] Said feeding arrangement FA comprises a second hydraulic pump Hp2 driven by means of a dedicated second motor M2. The feeding arrangement also comprises a feed valve for controlling the feed of fresh hydraulic fluid to the closed-loop hydraulic circuit CL.

[0042] Both the feed device FA and the discharge device DA are in direct fluid connection with a tank which serves as a separate source T of hydraulic fluid.

[0043] There may be one or more filtering or cooling devices CD for treating the exhausted hydraulic fluid before feeding it to the closed hydraulic circuit CL through the feeding device FA. The filtering or cooling device CD may be arranged in connection with the fluid source T.

[0044] Figure 2 Some control principles for controlling flushing of a closed-loop hydraulic circuit are disclosed 1. The control 1 may be based on fluid control monitoring 2 or operational issues 3 or both. The fluid condition monitoring 2 may include sensed data about the properties of the hydraulic fluid 4. Then, 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 of the hydraulic fluid 5. The control unit may control flushing for cooling the temperature of the circuit. Alternatively, or in addition, there may be one or more fluid condition monitoring sensors or analysis devices for detecting the cleanliness 6 of the hydraulic fluid.

[0045] The operational problem 3 may involve detecting the operational state of the closed loop hydraulic circuit 7. The control may take into account the usage rate 8, the operating time 9, the size of the operating load 10, and may also schedule a pre-flush 11 prior to an upcoming load condition.

[0046] Furthermore, the control unit can detect the operating conditions 12 of the closed-loop hydraulic circuit operation. The control unit can then increase flushing, for example, when operating in harsh conditions and high temperatures.

[0047] Figure 3 A hydraulic system HS is disclosed, which is Figure 1 The hydraulic system shown in FIG. 1 differs 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 feed of hydraulic fluid in the open-loop hydraulic circuit Op to the auxiliary actuators Aa. The open-loop hydraulic circuit including the auxiliary actuators Aa may also be referred to as a common rail circuit.

[0048] The drawings and the related description are intended only to illustrate the idea of ​​the invention. The invention may vary in its details within the scope of the claims.

Claims

1. A mining vehicle (1), comprising: Movable vehicles (2); at least one mining operation device, the at least one mining operation device being mounted on the vehicle (2); as well as at least one hydraulic system (HS); The hydraulic system (HS) is provided with at least one closed-loop hydraulic circuit (CL), comprising: at least one first hydraulic pump (Hp1) driven by means of at least one first motor (M1); at least one hydraulic actuator (HA); and wherein the pressurized hydraulic fluid is directed to circulate in the closed-loop hydraulic circuit (CL) from the outlet port of the first hydraulic pump (Hp1) to the inlet port of the hydraulic actuator (HA), and further from the outlet port of the hydraulic actuator (HA) to the inlet port of the first hydraulic pump (Hp1); and a flushing system (FLS) comprising at least one feeding device (FA) for feeding a limited amount of additional hydraulic fluid from a separate hydraulic fluid source (T) to the closed-loop hydraulic circuit (CL); and a draining device (DA) for draining a limited amount of used hydraulic fluid from the closed-loop hydraulic circuit (CL) to the separate hydraulic fluid source (T); wherein the discharge arrangement (DA) comprises at least one discharge valve (DV) which is actively controlled under the control of at least one control unit (CU), and wherein the fluid flow through the discharge valve (DV) is selectively controllable; Features The hydraulic system (HS) comprises an open hydraulic circuit (Op) serving as a common rail hydraulic circuit and configured to provide hydraulic fluid to the flushing system and to at least one hydraulic auxiliary actuator (Aa) coupled to the open hydraulic circuit (Op); and The open hydraulic circuit (Op) is provided with a second hydraulic pump (Hp2), which is driven by means of at least one dedicated second motor (M2) under the control of the control unit (CU).

2. The mining vehicle (1) according to claim 1, characterized in that: The closed-loop hydraulic circuit (CL) is provided with at least one sensing device (S) for sensing a property of the hydraulic fluid; And the control unit (CU) is configured to receive sensing data from the sensing device (S), and is configured to generate a control signal in response to the received sensing data for controlling at least the discharge valve (DV) of the flushing system (FLS).

3. The mining vehicle (1) according to claim 2, characterized in that: The sensing device (S) is a temperature sensor for sensing the temperature of the hydraulic fluid.

4. The mining vehicle (1) according to claim 2, characterized in that: The sensing device (S) is a fluid condition monitoring sensor for sensing a fluid property of the hydraulic fluid.

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

Images